CA1125891A - Automatic machine tool including a monitoring system - Google Patents
Automatic machine tool including a monitoring systemInfo
- Publication number
- CA1125891A CA1125891A CA243,688A CA243688A CA1125891A CA 1125891 A CA1125891 A CA 1125891A CA 243688 A CA243688 A CA 243688A CA 1125891 A CA1125891 A CA 1125891A
- Authority
- CA
- Canada
- Prior art keywords
- machine tool
- function
- transducer
- test
- test function
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H1/00—Measuring characteristics of vibrations in solids by using direct conduction to the detector
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D55/00—Safety devices protecting the machine or the operator, specially adapted for apparatus or machines dealt with in this subclass
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
- B23Q11/00—Accessories fitted to machine tools for keeping tools or parts of the machine in good working condition or for cooling work; Safety devices specially combined with or arranged in, or specially adapted for use in connection with, machine tools
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
- B30B15/28—Arrangements for preventing distortion of, or damage to, presses or parts thereof
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T83/00—Cutting
- Y10T83/04—Processes
Abstract
45,361 AUTOMATIC MACHINE TOOL INCLUDING A
MONITORING SYSTEM
ABSTRACT OF THE DISCLOSURE
An automatic punch press and monitoring system.
The monitoring system includes a piezoelectric accelerometer mounted within the stationary die shoe of the punch press, and electronic circuitry including a variable gain ampli-fier, a detector, an integrator, and a comparator. The monitoring system is manually placed in a "LEARN" mode whereupon the signal produced by the accelerometer during normal operation of the punch press is amplified, detected, and integrated over the time period of one stroke to pro-duce a test function. The gain of the amplifier is auto-matically adjusted during successive normal strokes of the punch press until the test function is equal to an arbitrary set point, thereby establishing a reference function. The monitoring system is then automatically placed in an "AUTO
CONTROL" mode whereupon on each succeeding stroke, with the gain of the amplifier fixed, the test function produced is compared with the reference function. If the test func-tion is above a first high limit level corresponding to a percentage of the reference function and below a second high limit level corresponding to a second percentage of the reference function a check alarm is activated. If the test function is above the second high limit level or below a low limit level corresponding to a third percentage of the reference function the punch press is shut down.
MONITORING SYSTEM
ABSTRACT OF THE DISCLOSURE
An automatic punch press and monitoring system.
The monitoring system includes a piezoelectric accelerometer mounted within the stationary die shoe of the punch press, and electronic circuitry including a variable gain ampli-fier, a detector, an integrator, and a comparator. The monitoring system is manually placed in a "LEARN" mode whereupon the signal produced by the accelerometer during normal operation of the punch press is amplified, detected, and integrated over the time period of one stroke to pro-duce a test function. The gain of the amplifier is auto-matically adjusted during successive normal strokes of the punch press until the test function is equal to an arbitrary set point, thereby establishing a reference function. The monitoring system is then automatically placed in an "AUTO
CONTROL" mode whereupon on each succeeding stroke, with the gain of the amplifier fixed, the test function produced is compared with the reference function. If the test func-tion is above a first high limit level corresponding to a percentage of the reference function and below a second high limit level corresponding to a second percentage of the reference function a check alarm is activated. If the test function is above the second high limit level or below a low limit level corresponding to a third percentage of the reference function the punch press is shut down.
Description
B AOI~n o~
This invention relates to machine tools and more;
~'f~t3~
45,361 specifically to maGhine tools including means for auto-matically controlling the operation thereo~.
,.
In an indust~1al SQCiet~ there ls a con~ant demand ~or large quantities o~ ldentlcal par~s ~or u~e in manufacturing a wide variet~ o~ articlesO M~ny ~ypes o~
parts are produced by perfo~ming a .repetitive mechanical operation upon ~tock material using a machine tool. One t~pe o~ machine tool emplo~s a rotatin~ spindle to perform operations such as g~inding or bor~ng. ~nother type of machine tool use~ a reciprocating hammer or ram to perform ~unctions such as ~or~ing~ planning, swaging, or punching~
Both types perform repetitive operations, with each opera~ion cycle ha~ing a substantially equal time periodg i.e~, the time required for a spindle to make one re~olutio~ or the time required for a r2m to complete one stroke and return to its starting position~
Au~omatic operation of ~hese machines allows repetitive cycling ~ithou~ the need ~or an operat~r to 20 initiate each cycle O A large rlumber o~ operations are perfo~med per unit o~ time in this manner. However~ the ~ypical machine does not have the ability to detect improper operation~0 For example~ it is no~ ~usual for a pu~ch press to produce h~ndreds o~ sa~le pa~t5 because o~ a ~aulty die~ ~mproper stock ~eeding9 or ~ailure o~ 3~ubrica-tion,. These mal~ ctions are detected and correated by ~uality con~rol personnel ar~d m~chlne operators~.
E~en more serious ls the no~ infrequent occurrence o~ a forei~n body becoming wedgad betwaen the tool ~I}rfaces.D
30 :En a punch press, :~or example~ this can re~ult in a badl~
~2--9 ~
1~5,361 damaged die or even a d~maged press. T~hen this happens it is necessary to halt operation of the pre~s and repair or replace the d~maged componen~s before product~on c~n resume~ S~.nc~ a damaged d~e can cosk hundred~ or ~v~n thousands of dollars to repair, the cost of malntenance and repair of dies is a significant ~raction o~ ~he cost of operating an automatic punch press ~acllit,y.
It T~ould be desirable to prov~de a system which can detect improper machi~e tool operation and take corrective action before producing a large quantity o~
faulty par~s or dama~ing the tool~ One device for detecting improper operation of a punch press is described in U~SO
paten~ No. 3~4449390 issued to ~ictor 5~ Breiden~ach and Patrick V. Close. This device employs a pie~oelectric transducer to detect accelera~ing distur~ances produced by the p~nch press. Peak amplitudes produced by ~he transducer during normal operat~on o~ the punch press are compared to peak amplitudes produced by the transducer during subseque~t opera~ion of the punch pressO If a signal peak from the tr~nsducer is greater than peaks produced during normal operation, the device will shut down the p~nch press.
Abnormally large peaks are produced ~hen ~oreign ma~erial lodges in the p~nch press or upon occurrence of some other serious mal~unctlons~ However9 many types of irregular or abnormal machine tool operation do not produce abnormall~ large peaks, inc~uding conditions leadlng to serious failure~ Thus? many ~ypes o~ mal~unctions are not de~ected by merely monitorlng peak amplitudes o~
signals produced by ~he transducer~ ~t is desirable to ~rovide an automa~ic machine tool system which would detect -3~
JS~l 1~53361 other types of abnormal operation including die wear or lack of lubrica~ion~ It is also desirable ko provide a system providing hlghly aut,omated operation requirlng a minlmum of operator action and calibration at ~ar~up, thereby pro~iding a versatile machine whlch is easily set up ~or dif~erent 3obs~
SUMMARY OF THE INVENTION
In accordance wikh the prlnciples of the present invention, there is provided a machlne tool system ~or per~orming a repetitive operation upon a workpiece comprising a machine too7 and a monitoring system. The monitoring system compri~es a transducer mounted în association with the machine tool ~or producing a signal in response to mechanical impulses de~e~oped by operat~on o~ the machine tool~ The signal is detected and applied to the input of means ge~era~ng a test function which is a ~unction of both time and the amplitude o~ the transducer signal. Me~ns are provided Xor producing a re~erence ~unction proportion~l to the test ~unction evaluatèd.during normal operation o~ the machine tool and for comparing this re~erence functlon wi~h the test ~unction e~aluated during subseque~ operation~
The compara~or generates an output signal ~or con~rolling operation of the machine tool ~hen the test ~u~ction and the reference ~nction differ ~y mo~e than a predete~mined a~ount.
BRIEF DESCRIPTION OF THE DRAWq~
The in~ention may be more readily under~tood by referenc~ to ~he drawings, in whlch:
Figure 1 sho~s a punch press and monito~lng syst~m constructed in accordance with the pre~ent in~entio~;
9~
1~5t361 ~ igure 2 is a block diagram of ~he monitoring system;
Figure 3 represents the signal produced a~ ~he output o~ the deteckor 56 sho~ in Fig~ 2 during ~ou~ normal ~unch pre~s strokes ~ollowed ~ a punch pre~s ~troke ~n which a serious jam has occurred3 Pigure 4 represents the sig~lal produced a~ the output of the amplifier 54 shown in Fig~ 2 du~ing a no~mal s~roke o~ a punch press haYing a di~eren~ die than the press of Pigure 3;
Fi~ure 5 represent~ the signal produced as in ~igure 4 during a str~ke ;n which a ~ailure o~ the ~eed mechanism has occurred~ producing a miscut;
Figure 6 represents the signal produced as in Figure 4 ~or a stro~a in which ~he die has become w~rn, producing a part having a ~urr; and ~ igure 7 sho~ the monitoring system con~rol box.
Throughou~ the dra~ngs~ like re~erence charac~ers rePer to like elements~
Referring now to the dra~ings~ and Fi~ure 1 in particular, there i~ shown an automa~ic punch press and monitoring sy~tem constructed according to the principles o~
the presen~ in~e~tion. A pu~ch prass 10 includes a base 12 and a generally C-shapad frame 14 at~ached to ~he base 12 The lower arm 16 of the ~r~me 14 Po~ms a bo~ste~ plate 1 upon which ~s mount~d a sta~iona~ die shoe 20. A drive sha~t 22 extends trans~erse~y through ~he upper a~m o~ the fra~e 14 and has a~tached to it a fl~wheel 24~ Also a~tached to the dri~e sha~t 22 i9 a mecha~ism in the in~erior 5~ ~ ~
45,361 of the frame 14 .for converting rotary motion o~ the drive shaft into reciprocating vertical mok~on o~ a ram 26, ~ttached to the ram 26 i5 a movable die shoe 2~ ~aving a plural-ity of surfaces which coopera~e ~d ma~e with corresponding sur~aces in the stationar~ die shoe 20 attached to ~he bolster pla~e l~
S~ock material 30~ ~uch as ribbon steel~ ls fed between the die shoes 20 and 2~ by a feed mechanism not shown. Rotation of the dri~e ~haft 22 causes the ram 26 and attached mo~able die shoe 2~ ~o be dri~en ~th great force down onto the stock ma~erial 30 and into ~he engagement with the sta~io~ary die ~hoe 20. ~he ~orce of the blow causes pieces to be punched~ bent9 or otherwisa ~o~med from ~he stock material 30, thereb~ producing shaped metal parts~
In normal operation the drive shaft 22 ls con~i~uo~sly rotat~ng, causin~; reciproca~ion of the ram 26.. The feed mechan~sm is synchroni~ed ~th operation o~ the drive sha~
to ad~ance ~he ribbon steel 30 after each punch stroXe?
~hereby presenti~g fresh material to the mating sur~aces 20 o~ the movin~ and stationary die shoe~ and producing a con-tinuous output o~ shaped metal pa~ts~
located next -to ~he punch press 10 on a separa~a psdestal 32 are the operatlng con~rol~ 34 ~or the punch press. The~e controls allow ~he operators to inch the press through small incremants o~ a complete revolution o~ t;he d~lve sha~t 22, to ~nitiate sin~le strokes of the punch press~ and to initiate continuous oper~ion of the punch press~ Loca~ed abo~e the operating con~rols 34 is the monitoring sys~em con~rol box 36~, The monito~îng sy~tem eontrol box 36, sho~m more clearly in F~gure 7~ includes ~6~
9~
~5,361 three ligh~ed pushbutton controls 3~, 40, 42 and two warni~g lights 44~ 46 A transducer 4~, such as a piezoelect~ic accelero~
meter7 is mounted in a threaded hole within khe ~ationary dle shoe 20. Operatlon o~ the punch press 10 caus~s th0 transducer 4~ to produce an electrical signal in response to mechanical implllses g~nerated in the dle shoe~ by the punch pres~ operation. The transducer is connected by coaxial cable to an electronic circuikry o~ the monitorlng system 50 contained within the monitoring system control bàx 36. The monitoring s~stem 50, shown in block diagram ~orm in Figure 2, includes impedance matching circuitry 52 to convert the high impedance ou~put o~ the ~ransducer to low impedance required by succeedlng stages of the monitoring system~ The output o~ the impedance ma~ching clrcuitry 52 is con~ected ~o the input of a variable gain ~mplifier 540 The output of the ~ariable gain amplifier 54 is connected to a detector device 56 to convert to direct current the alternating current signals produced by the trans;
ducer 4~ and passed b~ preceding stages o~ the monitorlng system.
The ou~put from the detector 56 ~s ~ed to the inp~t o~ an inte~rator 5~ which computes khe time integral of the s~-gnal ~rom the detector 56~ The output of the integrator 5~ constitutes a test function which is ~ed into a comparator 60 to comp~re the test function with a predetermined re~erence ~unction ~nd actuate circu~s 62 or 6~ ~hen the test signal exceeds the reference level by more than a certain ~mount.
Re~erring once again ~o ~igure ~7 a momen~ary 5 ~
45~361 contact switch 66 attached to the ~rame l~ is ac~uated onc~
for every revolution of the dri~e ~ha~t 22, thereby pro-ducing a synchronization ~ulse when the ram 26 is at khe top of the stroke. The momentary contact s~tch 66 18 connected to the monitoring system control box 36 to féed the synchronization pulses to digital sequencing logic indicated ak 6~ in Figure 2. Other inputs to the digital sequencing logic are provided by the lighted pushbuttons 3B, 40 and 42 on the monltol~ng system eontrol box.
Gutputs from the digital sequencing logie 6~ are eonnected to the va~iable gain amplifi0r 54 and reset dev~ce 70 in-dicated in Figure 2. m e digital se~uencing logie 6~
operates to control the operation of the monitoring system as will be hereinafter dasbribed.
The output of the monitoring system is a relay-contact 72 which is eonneeted in series ~th the control circuitry of the punch press~ The contact 72 is normally closed, thereby permitting normal operation o~ the punch press without operation of the monitoring s~stem. The relay contact 72 is opened causing a shut do~n o~ the punch press, under conditions to be deseribed hereina~ter. Other types o~ de~ices for generating a control signal, such as a trlac, could also be used in plaee of the rela~ contact 72.
The signal produced by the transducer 1~ during operation of the punch press lO is shown in ~igure 3, after passing through the amplifier 54 and dekector 56. The patterns indicated a~ 72, 74 9 76 and 7~ represent normal punch stroXes producing acceptable parts~ During the k~me ~nterval between the poin~s indicated at 7~ and ~0 8t~3~
~5,361 a small piece o~ one of ~he die shoes ~0 and 2~ broke off and became lodged be~ween ~he surfaces of the die ~hoes. The next succeeding stroke indicat~d at ~0 produced the tran3-ducer signals shown~ and caused severe damage to the die shoes 20 and 2~ before ~he press 10 was shut down by operator action. Prior art device,s employed means ~o det~ct abnormally high peak transducer readings and shut do~ th~
machine tool ~henever the signal exceeded a given threshold levelO Such devices would detect ~he condition shown in Figure 3, and successfully shut do~ the press before severe damage occurred.
Figure 4 shows the signal produced at the output o~ the ~mplifier 5~ during a normal stroke of a punch press and die combination dlf~erent from that shown in Figure 3.
In Figure 5 a similarly obtained signal is shown wherein a malfunction has occurred in the ~eed mechanlsm preventing the stock 30 from being fully ad~anced the proper distance in~o the die shoes upon successiYe s~rokes. The punch thus slightly overlaps the holes produced in the previous stroke. This condition could lead to defective parts and rapid wear o~ the die shoes~ Note that the p2ak signals of Figure 5 are equal to or less than the peak signals produced during normals operation o~ the press as sho~n in Figure 4~ Thus, a monitoring system employing means responding only to abnormally high peak signals produced by the transducer would not detect the mal~unction indicated in Figure 5O
Figure 6 shows a signal obtained as in Figures 4 a~d 5 during operation of the press when the die shoes 20 and 2~ have become ~orn and parts being prod~ced ha~e slgni~
~s~
~5,361 ficant burrs. This condition al50 leads to unaccep~able parts, Again, the peak signals produced under ~he~e unde3irable conditions are equal to or less than peak signals produ~ed during nvrmal operation~ and a de~rice employing a ~eak signal monitor would not detect th~ mal-~unction~
A monitoring system employing means generating a test function which is a ~unction of both time and the amplitude o~ the signal produced by the transducer during operation of the machine tool will significantly increase the sensiti~ity o~ the monitoring system ~o abnormal oper~
ating conditions of ~he punch press. ~y employing means producing a synchronization pulse a~ the same time during each repetitive machine tool opera~ion the signal re~
lationship to the time period o~ operation of the machine tool can be analyzed. In the monitoring sy~tem indicated in Figure 2, the synchronization pulses produced by the momentary contact switch 56 are ~ed through the sequenci-ng logic 6~ to ~he integrator 5~ which 5ums the sign~l produced by the transducer 4~ These synchronization pulses are used to reset the integrator 5~ at a glven poin~ in the time period of the punch press stroke and compute ~he ~ime in~egral of the transducer signal o~er the period of the stroke. By i~egra~ing the signal produced by the transducer 4~ during one repetitive machine tool operation under non~al conditisns and maintaining amplifier gain settings~ the time integral produced over suc~essi~e machine tool opera~ions can be compared~ The integrator is thus generating a test functlon which is a function of bo~h transducer ~ignal amplitude and of time~ allowing the monitoring ~ystem to ~ 0--5 8~ ~
~,361 analyze the total signal produced o~er the t~me period of one repeti~ive machine tool operation rather than merely the peak amplikude o~ signals 60 produced~ By analyzing and comparing the ~ime in~egral of the signal produced, malfunc~ions cau~ing either higher than no~nal or lower than normal time integrals can be detected~
For example9 total failure o~ stock feed would result in a much lower time integral than du~lng no~mal operation. This ~ower time inkegral would result in an alarm bein~ produced.
To operate the automa~ic punch pres~ and monitor~
ing system employing principles o~ the presen~ invention ~he opera~or sets up the press 10 in a normal manner~
Using the standard punch press operating controls 34 he initiates repetitive operation of the press and ~erif~es that acceptable parts are being producedO l~ith normal operation so ver~ied, the operator pre~ses the "LEARN" lighted pushbutton 3~ whlch is immediately illuminated. From this point onp opera~ion is completely au~omatic and no ~urther opera~or action is required. The digital se-20 quencing logic 6~ causes the variable gain amplifier 51 to be set to its lowest gain leYel. Signals from the transducer 4~ are fed through th~ impedance matching circuit 52, the amplifier 54~ and the detector 56 in~o the integrator 5~. The signal is summed by the integrator until the first synchronization pulse is received b~ the digital sequencing log~.c 6~ from the mo~entary con~act switch 661~ If the test function, that is~ the in~egrator ou~put signalg is at this time lower th~ a pred~termined arbitrarr ~et point le~el~ for ex~mple 1 volt7 the di~ikal 30 sequencing logic 6~ ~ ncreases the gain of` the ~ariable ~5~361 gain ampllfier 5h prior ~o the next succeeding punch press strokeO The signal from the transducer 4~ during this stroke is similarly ampli~ied~ detected, integrated and com-pared againsk the 1 volt level. The gain o~ ~he ampli~ier 54 is au~omatically increased by the digi~al ~equencing lo~ic 6~ on successive strokes until the ~est funckion produced by khe i.ntegrator 5~ during a stroke exceeds ~he arbitrary set polnt level o~ 1 volt. On succeeding strokes ~ollowing this stroke at w~ich the ~est func~ion exceeded the se~
point level, the d~gital sequencing logic 6~ automatically increases the set point level above 1 vol~ un~il the dif-ference between the test func~ion over one complete stroke and the arbitrary set point le~el is less than approxima~ely ol2 ~olts. The set point level thus represen~s the test function evaluated during normal operation o~ the press~
It ~hen becomes the re~erence ~u~ckion~ The digital seq~encing logic 6~ then extinguishes the "LEARN" lighted pushbutton 3 and illuminates the "AUTO CONTROL't lighted pushbutton 40 on the monitori~g system contr~l box 36~ The ~ystem is now in "AUTO C`ONTROL" mode and the gain of the ~ariable gain ampli-fier 54 will be maîntained on all succeeding stroke~ of the punch press~ A reference ~unction has thus been automatlcally generated~ The signal produced by the ~ransducer 4~ during ~ -all successive strokes is then amplified at ~his gain level9 detected, and integrated.
I~ the test function e~aluated on any succeeding stroke exceeds the re~erence ~unction by a ~irst pre-determined amount~ the !ICHECK3l ligh~ 4~ is illuminated upon the monitoring s~stem control box 364 This inaicakes 5~9 ~
~59361 that a malfunctlon has occurred which is not ~erious enou^gh to warran~ shu~tlng down ~he press bu~ demands the operator's attentlon. If the output of the integra~or S~
exceeds the reference ~unction b~ a second pr~de~ermined amount larger than ~he .Plr~t predetermined amoun~ khe "ALA~MI' lighk ~6 is illuminated~ In addikion, the monitor~ng sys~em opens the relay contact 72 ~hen the next syn-chroni~ation pulse is recolved. This causes the control circuit o~ the punch press to shut down the press~ This shutdown operation and ~ALA~MI' light illumlnation is also per~ormed lf the test func~ivn during any stroke o~ the punch press is below the reference ~unction by more than a predete~mined amount~ indicating a mal~unction o~ the punch press such as ~ailure of the ~eed mechanism~
At any time during operation of ~he punch press the operator can energize the '~ANUAL CONTROL'~ lighted pushbutton ~2. This removes the monitoring system ~rom any con~rol o~ the punch press. However~ ~he gai~ o~ ~he ~ariable gain ampl~fier 54 remains at the setting determined during the previous "LEARNl' operation~ Thus~ the operator can later energize the "AUTO CONTROL" lighted push~utton 407 reinser~ing the monitoring system into the con~rol loop and comparing the signal produced by the transducer 4~ during all succeeding strokes to normal conditions of the previou~
t'LEARN" operation.
The transducer in ~h~^s described embodiment is mounted upon the stationary dîe shoe 20 of the machine tool. IS could, however9 be mounted in the bols~er plate 1 of the punch press 10 or other co~venient position in association ~th a machine tool wherein mechanical impulses . .
58~3~L
1~5,361 produced by the operation o~ the machine tool l~ould be detected by the transducer. Cther types of transducers can also be us~d~ For instance~ a microphone can be mounted in ~he vicinity of ~he two die ~hoe~ ~o produce ~
signal in response to the sound produced by th~ operation of the punch press, The principles o~ the preseNt invention can also be employed in machine ~ools using a rotating spindleO
A magnetic pickup can be used to produce a synchronization ~0 pulse during each revolu~ion of the spindle~ The slgnal produced by the transducer during each revolution of the spindle can then be analyzed and ~ntegrated as was previously described for the punch press operation. Such a system would detect conditions such as improper tool speed, improper cutting rate, dull or broken tool bits, excesslve vibra~ions and lack of proper lubrication to the cutti~g surfaces~
~ ore detailed analysis could also be accomplished using principle~ o~ the present in~ention. For example, two or more integrators could be used to anal~e different portion~ o~ the m~chine tool opera~ion cycle~ Gating cir-cuit~y could be used to turn on a high~sensitivity integra~or duri~g portlons o~ th~ cycle d~ring which nonmal opera~lon of the machine tool produce~ very low ~mplitude signals and a second integrator of lower sensitivity could be turned on only dur~ng those portions o~ the cycle when normal operation produces higher level signa~s~ Thus much ~iner resolu~ion could be obtained a~d closer toleranse alarming ac~omplished~
For even ~x~ater sophistica~ion~ a computer could be employed to mea~ure the ampli~ude of the sign~l pr~duced 5B~ ~5 7361 at each o~ man~ small incr~men~s o~ time over the period of one normal repetiti~e machine tool operatlon~ The amplitude durin~ each increment would be stored in computer memo~y, the set of amplitude value~ constituting a refer~nce function correspondin~ to the time integral generated in the previou~ly described embodimen~ The s~ of signal amplitude va~ues produced by the transducer at each increment o~ t~me during successive machine tool operations would consti~u~e a test function ~o be compared with the reference function. This computer control monitoring system would be use~ul where a very high degree of precision is required in parts pro~uced by ~ machine tool. A precise computer analysis o~ the test functions as a ~unction o~
time would also be useful as a diagnos~c tool in evaluatin~
die performance and dle design~
From ~he foregQing~ it is seen that the present i~ven~ion has provided a new and lmproved automatic machine tool and monitoring system~ ~hile the inven~ion has been shown and described in only one ~orm, it ~11 be ob~ious to ~hose skllled in the art that i~ is no~ so limited~ but is susceptible ~o various changes and modifica~ions without depart~ng ~rvm the splrit thereof.
This invention relates to machine tools and more;
~'f~t3~
45,361 specifically to maGhine tools including means for auto-matically controlling the operation thereo~.
,.
In an indust~1al SQCiet~ there ls a con~ant demand ~or large quantities o~ ldentlcal par~s ~or u~e in manufacturing a wide variet~ o~ articlesO M~ny ~ypes o~
parts are produced by perfo~ming a .repetitive mechanical operation upon ~tock material using a machine tool. One t~pe o~ machine tool emplo~s a rotatin~ spindle to perform operations such as g~inding or bor~ng. ~nother type of machine tool use~ a reciprocating hammer or ram to perform ~unctions such as ~or~ing~ planning, swaging, or punching~
Both types perform repetitive operations, with each opera~ion cycle ha~ing a substantially equal time periodg i.e~, the time required for a spindle to make one re~olutio~ or the time required for a r2m to complete one stroke and return to its starting position~
Au~omatic operation of ~hese machines allows repetitive cycling ~ithou~ the need ~or an operat~r to 20 initiate each cycle O A large rlumber o~ operations are perfo~med per unit o~ time in this manner. However~ the ~ypical machine does not have the ability to detect improper operation~0 For example~ it is no~ ~usual for a pu~ch press to produce h~ndreds o~ sa~le pa~t5 because o~ a ~aulty die~ ~mproper stock ~eeding9 or ~ailure o~ 3~ubrica-tion,. These mal~ ctions are detected and correated by ~uality con~rol personnel ar~d m~chlne operators~.
E~en more serious ls the no~ infrequent occurrence o~ a forei~n body becoming wedgad betwaen the tool ~I}rfaces.D
30 :En a punch press, :~or example~ this can re~ult in a badl~
~2--9 ~
1~5,361 damaged die or even a d~maged press. T~hen this happens it is necessary to halt operation of the pre~s and repair or replace the d~maged componen~s before product~on c~n resume~ S~.nc~ a damaged d~e can cosk hundred~ or ~v~n thousands of dollars to repair, the cost of malntenance and repair of dies is a significant ~raction o~ ~he cost of operating an automatic punch press ~acllit,y.
It T~ould be desirable to prov~de a system which can detect improper machi~e tool operation and take corrective action before producing a large quantity o~
faulty par~s or dama~ing the tool~ One device for detecting improper operation of a punch press is described in U~SO
paten~ No. 3~4449390 issued to ~ictor 5~ Breiden~ach and Patrick V. Close. This device employs a pie~oelectric transducer to detect accelera~ing distur~ances produced by the p~nch press. Peak amplitudes produced by ~he transducer during normal operat~on o~ the punch press are compared to peak amplitudes produced by the transducer during subseque~t opera~ion of the punch pressO If a signal peak from the tr~nsducer is greater than peaks produced during normal operation, the device will shut down the p~nch press.
Abnormally large peaks are produced ~hen ~oreign ma~erial lodges in the p~nch press or upon occurrence of some other serious mal~unctlons~ However9 many types of irregular or abnormal machine tool operation do not produce abnormall~ large peaks, inc~uding conditions leadlng to serious failure~ Thus? many ~ypes o~ mal~unctions are not de~ected by merely monitorlng peak amplitudes o~
signals produced by ~he transducer~ ~t is desirable to ~rovide an automa~ic machine tool system which would detect -3~
JS~l 1~53361 other types of abnormal operation including die wear or lack of lubrica~ion~ It is also desirable ko provide a system providing hlghly aut,omated operation requirlng a minlmum of operator action and calibration at ~ar~up, thereby pro~iding a versatile machine whlch is easily set up ~or dif~erent 3obs~
SUMMARY OF THE INVENTION
In accordance wikh the prlnciples of the present invention, there is provided a machlne tool system ~or per~orming a repetitive operation upon a workpiece comprising a machine too7 and a monitoring system. The monitoring system compri~es a transducer mounted în association with the machine tool ~or producing a signal in response to mechanical impulses de~e~oped by operat~on o~ the machine tool~ The signal is detected and applied to the input of means ge~era~ng a test function which is a ~unction of both time and the amplitude o~ the transducer signal. Me~ns are provided Xor producing a re~erence ~unction proportion~l to the test ~unction evaluatèd.during normal operation o~ the machine tool and for comparing this re~erence functlon wi~h the test ~unction e~aluated during subseque~ operation~
The compara~or generates an output signal ~or con~rolling operation of the machine tool ~hen the test ~u~ction and the reference ~nction differ ~y mo~e than a predete~mined a~ount.
BRIEF DESCRIPTION OF THE DRAWq~
The in~ention may be more readily under~tood by referenc~ to ~he drawings, in whlch:
Figure 1 sho~s a punch press and monito~lng syst~m constructed in accordance with the pre~ent in~entio~;
9~
1~5t361 ~ igure 2 is a block diagram of ~he monitoring system;
Figure 3 represents the signal produced a~ ~he output o~ the deteckor 56 sho~ in Fig~ 2 during ~ou~ normal ~unch pre~s strokes ~ollowed ~ a punch pre~s ~troke ~n which a serious jam has occurred3 Pigure 4 represents the sig~lal produced a~ the output of the amplifier 54 shown in Fig~ 2 du~ing a no~mal s~roke o~ a punch press haYing a di~eren~ die than the press of Pigure 3;
Fi~ure 5 represent~ the signal produced as in ~igure 4 during a str~ke ;n which a ~ailure o~ the ~eed mechanism has occurred~ producing a miscut;
Figure 6 represents the signal produced as in Figure 4 ~or a stro~a in which ~he die has become w~rn, producing a part having a ~urr; and ~ igure 7 sho~ the monitoring system con~rol box.
Throughou~ the dra~ngs~ like re~erence charac~ers rePer to like elements~
Referring now to the dra~ings~ and Fi~ure 1 in particular, there i~ shown an automa~ic punch press and monitoring sy~tem constructed according to the principles o~
the presen~ in~e~tion. A pu~ch prass 10 includes a base 12 and a generally C-shapad frame 14 at~ached to ~he base 12 The lower arm 16 of the ~r~me 14 Po~ms a bo~ste~ plate 1 upon which ~s mount~d a sta~iona~ die shoe 20. A drive sha~t 22 extends trans~erse~y through ~he upper a~m o~ the fra~e 14 and has a~tached to it a fl~wheel 24~ Also a~tached to the dri~e sha~t 22 i9 a mecha~ism in the in~erior 5~ ~ ~
45,361 of the frame 14 .for converting rotary motion o~ the drive shaft into reciprocating vertical mok~on o~ a ram 26, ~ttached to the ram 26 i5 a movable die shoe 2~ ~aving a plural-ity of surfaces which coopera~e ~d ma~e with corresponding sur~aces in the stationar~ die shoe 20 attached to ~he bolster pla~e l~
S~ock material 30~ ~uch as ribbon steel~ ls fed between the die shoes 20 and 2~ by a feed mechanism not shown. Rotation of the dri~e ~haft 22 causes the ram 26 and attached mo~able die shoe 2~ ~o be dri~en ~th great force down onto the stock ma~erial 30 and into ~he engagement with the sta~io~ary die ~hoe 20. ~he ~orce of the blow causes pieces to be punched~ bent9 or otherwisa ~o~med from ~he stock material 30, thereb~ producing shaped metal parts~
In normal operation the drive shaft 22 ls con~i~uo~sly rotat~ng, causin~; reciproca~ion of the ram 26.. The feed mechan~sm is synchroni~ed ~th operation o~ the drive sha~
to ad~ance ~he ribbon steel 30 after each punch stroXe?
~hereby presenti~g fresh material to the mating sur~aces 20 o~ the movin~ and stationary die shoe~ and producing a con-tinuous output o~ shaped metal pa~ts~
located next -to ~he punch press 10 on a separa~a psdestal 32 are the operatlng con~rol~ 34 ~or the punch press. The~e controls allow ~he operators to inch the press through small incremants o~ a complete revolution o~ t;he d~lve sha~t 22, to ~nitiate sin~le strokes of the punch press~ and to initiate continuous oper~ion of the punch press~ Loca~ed abo~e the operating con~rols 34 is the monitoring sys~em con~rol box 36~, The monito~îng sy~tem eontrol box 36, sho~m more clearly in F~gure 7~ includes ~6~
9~
~5,361 three ligh~ed pushbutton controls 3~, 40, 42 and two warni~g lights 44~ 46 A transducer 4~, such as a piezoelect~ic accelero~
meter7 is mounted in a threaded hole within khe ~ationary dle shoe 20. Operatlon o~ the punch press 10 caus~s th0 transducer 4~ to produce an electrical signal in response to mechanical implllses g~nerated in the dle shoe~ by the punch pres~ operation. The transducer is connected by coaxial cable to an electronic circuikry o~ the monitorlng system 50 contained within the monitoring system control bàx 36. The monitoring s~stem 50, shown in block diagram ~orm in Figure 2, includes impedance matching circuitry 52 to convert the high impedance ou~put o~ the ~ransducer to low impedance required by succeedlng stages of the monitoring system~ The output o~ the impedance ma~ching clrcuitry 52 is con~ected ~o the input of a variable gain ~mplifier 540 The output of the ~ariable gain amplifier 54 is connected to a detector device 56 to convert to direct current the alternating current signals produced by the trans;
ducer 4~ and passed b~ preceding stages o~ the monitorlng system.
The ou~put from the detector 56 ~s ~ed to the inp~t o~ an inte~rator 5~ which computes khe time integral of the s~-gnal ~rom the detector 56~ The output of the integrator 5~ constitutes a test function which is ~ed into a comparator 60 to comp~re the test function with a predetermined re~erence ~unction ~nd actuate circu~s 62 or 6~ ~hen the test signal exceeds the reference level by more than a certain ~mount.
Re~erring once again ~o ~igure ~7 a momen~ary 5 ~
45~361 contact switch 66 attached to the ~rame l~ is ac~uated onc~
for every revolution of the dri~e ~ha~t 22, thereby pro-ducing a synchronization ~ulse when the ram 26 is at khe top of the stroke. The momentary contact s~tch 66 18 connected to the monitoring system control box 36 to féed the synchronization pulses to digital sequencing logic indicated ak 6~ in Figure 2. Other inputs to the digital sequencing logic are provided by the lighted pushbuttons 3B, 40 and 42 on the monltol~ng system eontrol box.
Gutputs from the digital sequencing logie 6~ are eonnected to the va~iable gain amplifi0r 54 and reset dev~ce 70 in-dicated in Figure 2. m e digital se~uencing logie 6~
operates to control the operation of the monitoring system as will be hereinafter dasbribed.
The output of the monitoring system is a relay-contact 72 which is eonneeted in series ~th the control circuitry of the punch press~ The contact 72 is normally closed, thereby permitting normal operation o~ the punch press without operation of the monitoring s~stem. The relay contact 72 is opened causing a shut do~n o~ the punch press, under conditions to be deseribed hereina~ter. Other types o~ de~ices for generating a control signal, such as a trlac, could also be used in plaee of the rela~ contact 72.
The signal produced by the transducer 1~ during operation of the punch press lO is shown in ~igure 3, after passing through the amplifier 54 and dekector 56. The patterns indicated a~ 72, 74 9 76 and 7~ represent normal punch stroXes producing acceptable parts~ During the k~me ~nterval between the poin~s indicated at 7~ and ~0 8t~3~
~5,361 a small piece o~ one of ~he die shoes ~0 and 2~ broke off and became lodged be~ween ~he surfaces of the die ~hoes. The next succeeding stroke indicat~d at ~0 produced the tran3-ducer signals shown~ and caused severe damage to the die shoes 20 and 2~ before ~he press 10 was shut down by operator action. Prior art device,s employed means ~o det~ct abnormally high peak transducer readings and shut do~ th~
machine tool ~henever the signal exceeded a given threshold levelO Such devices would detect ~he condition shown in Figure 3, and successfully shut do~ the press before severe damage occurred.
Figure 4 shows the signal produced at the output o~ the ~mplifier 5~ during a normal stroke of a punch press and die combination dlf~erent from that shown in Figure 3.
In Figure 5 a similarly obtained signal is shown wherein a malfunction has occurred in the ~eed mechanlsm preventing the stock 30 from being fully ad~anced the proper distance in~o the die shoes upon successiYe s~rokes. The punch thus slightly overlaps the holes produced in the previous stroke. This condition could lead to defective parts and rapid wear o~ the die shoes~ Note that the p2ak signals of Figure 5 are equal to or less than the peak signals produced during normals operation o~ the press as sho~n in Figure 4~ Thus, a monitoring system employing means responding only to abnormally high peak signals produced by the transducer would not detect the mal~unction indicated in Figure 5O
Figure 6 shows a signal obtained as in Figures 4 a~d 5 during operation of the press when the die shoes 20 and 2~ have become ~orn and parts being prod~ced ha~e slgni~
~s~
~5,361 ficant burrs. This condition al50 leads to unaccep~able parts, Again, the peak signals produced under ~he~e unde3irable conditions are equal to or less than peak signals produ~ed during nvrmal operation~ and a de~rice employing a ~eak signal monitor would not detect th~ mal-~unction~
A monitoring system employing means generating a test function which is a ~unction of both time and the amplitude o~ the signal produced by the transducer during operation of the machine tool will significantly increase the sensiti~ity o~ the monitoring system ~o abnormal oper~
ating conditions of ~he punch press. ~y employing means producing a synchronization pulse a~ the same time during each repetitive machine tool opera~ion the signal re~
lationship to the time period o~ operation of the machine tool can be analyzed. In the monitoring sy~tem indicated in Figure 2, the synchronization pulses produced by the momentary contact switch 56 are ~ed through the sequenci-ng logic 6~ to ~he integrator 5~ which 5ums the sign~l produced by the transducer 4~ These synchronization pulses are used to reset the integrator 5~ at a glven poin~ in the time period of the punch press stroke and compute ~he ~ime in~egral of the transducer signal o~er the period of the stroke. By i~egra~ing the signal produced by the transducer 4~ during one repetitive machine tool operation under non~al conditisns and maintaining amplifier gain settings~ the time integral produced over suc~essi~e machine tool opera~ions can be compared~ The integrator is thus generating a test functlon which is a function of bo~h transducer ~ignal amplitude and of time~ allowing the monitoring ~ystem to ~ 0--5 8~ ~
~,361 analyze the total signal produced o~er the t~me period of one repeti~ive machine tool operation rather than merely the peak amplikude o~ signals 60 produced~ By analyzing and comparing the ~ime in~egral of the signal produced, malfunc~ions cau~ing either higher than no~nal or lower than normal time integrals can be detected~
For example9 total failure o~ stock feed would result in a much lower time integral than du~lng no~mal operation. This ~ower time inkegral would result in an alarm bein~ produced.
To operate the automa~ic punch pres~ and monitor~
ing system employing principles o~ the presen~ invention ~he opera~or sets up the press 10 in a normal manner~
Using the standard punch press operating controls 34 he initiates repetitive operation of the press and ~erif~es that acceptable parts are being producedO l~ith normal operation so ver~ied, the operator pre~ses the "LEARN" lighted pushbutton 3~ whlch is immediately illuminated. From this point onp opera~ion is completely au~omatic and no ~urther opera~or action is required. The digital se-20 quencing logic 6~ causes the variable gain amplifier 51 to be set to its lowest gain leYel. Signals from the transducer 4~ are fed through th~ impedance matching circuit 52, the amplifier 54~ and the detector 56 in~o the integrator 5~. The signal is summed by the integrator until the first synchronization pulse is received b~ the digital sequencing log~.c 6~ from the mo~entary con~act switch 661~ If the test function, that is~ the in~egrator ou~put signalg is at this time lower th~ a pred~termined arbitrarr ~et point le~el~ for ex~mple 1 volt7 the di~ikal 30 sequencing logic 6~ ~ ncreases the gain of` the ~ariable ~5~361 gain ampllfier 5h prior ~o the next succeeding punch press strokeO The signal from the transducer 4~ during this stroke is similarly ampli~ied~ detected, integrated and com-pared againsk the 1 volt level. The gain o~ ~he ampli~ier 54 is au~omatically increased by the digi~al ~equencing lo~ic 6~ on successive strokes until the ~est funckion produced by khe i.ntegrator 5~ during a stroke exceeds ~he arbitrary set polnt level o~ 1 volt. On succeeding strokes ~ollowing this stroke at w~ich the ~est func~ion exceeded the se~
point level, the d~gital sequencing logic 6~ automatically increases the set point level above 1 vol~ un~il the dif-ference between the test func~ion over one complete stroke and the arbitrary set point le~el is less than approxima~ely ol2 ~olts. The set point level thus represen~s the test function evaluated during normal operation o~ the press~
It ~hen becomes the re~erence ~u~ckion~ The digital seq~encing logic 6~ then extinguishes the "LEARN" lighted pushbutton 3 and illuminates the "AUTO CONTROL't lighted pushbutton 40 on the monitori~g system contr~l box 36~ The ~ystem is now in "AUTO C`ONTROL" mode and the gain of the ~ariable gain ampli-fier 54 will be maîntained on all succeeding stroke~ of the punch press~ A reference ~unction has thus been automatlcally generated~ The signal produced by the ~ransducer 4~ during ~ -all successive strokes is then amplified at ~his gain level9 detected, and integrated.
I~ the test function e~aluated on any succeeding stroke exceeds the re~erence ~unction by a ~irst pre-determined amount~ the !ICHECK3l ligh~ 4~ is illuminated upon the monitoring s~stem control box 364 This inaicakes 5~9 ~
~59361 that a malfunctlon has occurred which is not ~erious enou^gh to warran~ shu~tlng down ~he press bu~ demands the operator's attentlon. If the output of the integra~or S~
exceeds the reference ~unction b~ a second pr~de~ermined amount larger than ~he .Plr~t predetermined amoun~ khe "ALA~MI' lighk ~6 is illuminated~ In addikion, the monitor~ng sys~em opens the relay contact 72 ~hen the next syn-chroni~ation pulse is recolved. This causes the control circuit o~ the punch press to shut down the press~ This shutdown operation and ~ALA~MI' light illumlnation is also per~ormed lf the test func~ivn during any stroke o~ the punch press is below the reference ~unction by more than a predete~mined amount~ indicating a mal~unction o~ the punch press such as ~ailure of the ~eed mechanism~
At any time during operation of ~he punch press the operator can energize the '~ANUAL CONTROL'~ lighted pushbutton ~2. This removes the monitoring system ~rom any con~rol o~ the punch press. However~ ~he gai~ o~ ~he ~ariable gain ampl~fier 54 remains at the setting determined during the previous "LEARNl' operation~ Thus~ the operator can later energize the "AUTO CONTROL" lighted push~utton 407 reinser~ing the monitoring system into the con~rol loop and comparing the signal produced by the transducer 4~ during all succeeding strokes to normal conditions of the previou~
t'LEARN" operation.
The transducer in ~h~^s described embodiment is mounted upon the stationary dîe shoe 20 of the machine tool. IS could, however9 be mounted in the bols~er plate 1 of the punch press 10 or other co~venient position in association ~th a machine tool wherein mechanical impulses . .
58~3~L
1~5,361 produced by the operation o~ the machine tool l~ould be detected by the transducer. Cther types of transducers can also be us~d~ For instance~ a microphone can be mounted in ~he vicinity of ~he two die ~hoe~ ~o produce ~
signal in response to the sound produced by th~ operation of the punch press, The principles o~ the preseNt invention can also be employed in machine ~ools using a rotating spindleO
A magnetic pickup can be used to produce a synchronization ~0 pulse during each revolu~ion of the spindle~ The slgnal produced by the transducer during each revolution of the spindle can then be analyzed and ~ntegrated as was previously described for the punch press operation. Such a system would detect conditions such as improper tool speed, improper cutting rate, dull or broken tool bits, excesslve vibra~ions and lack of proper lubrication to the cutti~g surfaces~
~ ore detailed analysis could also be accomplished using principle~ o~ the present in~ention. For example, two or more integrators could be used to anal~e different portion~ o~ the m~chine tool opera~ion cycle~ Gating cir-cuit~y could be used to turn on a high~sensitivity integra~or duri~g portlons o~ th~ cycle d~ring which nonmal opera~lon of the machine tool produce~ very low ~mplitude signals and a second integrator of lower sensitivity could be turned on only dur~ng those portions o~ the cycle when normal operation produces higher level signa~s~ Thus much ~iner resolu~ion could be obtained a~d closer toleranse alarming ac~omplished~
For even ~x~ater sophistica~ion~ a computer could be employed to mea~ure the ampli~ude of the sign~l pr~duced 5B~ ~5 7361 at each o~ man~ small incr~men~s o~ time over the period of one normal repetiti~e machine tool operatlon~ The amplitude durin~ each increment would be stored in computer memo~y, the set of amplitude value~ constituting a refer~nce function correspondin~ to the time integral generated in the previou~ly described embodimen~ The s~ of signal amplitude va~ues produced by the transducer at each increment o~ t~me during successive machine tool operations would consti~u~e a test function ~o be compared with the reference function. This computer control monitoring system would be use~ul where a very high degree of precision is required in parts pro~uced by ~ machine tool. A precise computer analysis o~ the test functions as a ~unction o~
time would also be useful as a diagnos~c tool in evaluatin~
die performance and dle design~
From ~he foregQing~ it is seen that the present i~ven~ion has provided a new and lmproved automatic machine tool and monitoring system~ ~hile the inven~ion has been shown and described in only one ~orm, it ~11 be ob~ious to ~hose skllled in the art that i~ is no~ so limited~ but is susceptible ~o various changes and modifica~ions without depart~ng ~rvm the splrit thereof.
Claims (17)
1. A machine tool system for performing a repetitive operation upon a workpiece, said system comprising a machine tool and a monitoring system, said monitoring system comprising:
a transducer mounted in association with said machine tool for producing a signal in response to mechanical impulses developed by operation of said machine tool;
means for generating a test function which is a function of said transducer signal and also a function of time;
means for automatically generating a reference function representative of said test function evaluated during normal operation of said machine tool; and means for comparing said test function with said reference function and for generating a control signal for controlling operation of said machine tool when said test function and said reference function differ by more than a predetermined amount.
a transducer mounted in association with said machine tool for producing a signal in response to mechanical impulses developed by operation of said machine tool;
means for generating a test function which is a function of said transducer signal and also a function of time;
means for automatically generating a reference function representative of said test function evaluated during normal operation of said machine tool; and means for comparing said test function with said reference function and for generating a control signal for controlling operation of said machine tool when said test function and said reference function differ by more than a predetermined amount.
2. A machine tool system as described in claim 1 wherein said test function is evaluated for each repetitive machine tool operation.
3. A machine tool system for performing a repetitive operation upon a workpiece, said system comprising a machine tool and a monitoring system, said monitoring system comprising:
a transducer mounted in association with said machine tool for producing a signal in response to mechanical impulses developed by operation of said machine tool;
45,361 means for generating a test function which is a function of said transducer signal, said test function also being a function of time, means for generating a reference function represen-tative of said test function evaluated during normal operation of said machine tool; and means for comparing said test function with said reference function and for generating a control signal for controlling operation of said machine tool when said test function and said reference function differ by more than a predetermined amount.
a transducer mounted in association with said machine tool for producing a signal in response to mechanical impulses developed by operation of said machine tool;
45,361 means for generating a test function which is a function of said transducer signal, said test function also being a function of time, means for generating a reference function represen-tative of said test function evaluated during normal operation of said machine tool; and means for comparing said test function with said reference function and for generating a control signal for controlling operation of said machine tool when said test function and said reference function differ by more than a predetermined amount.
4. A machine tool system as described in claim 3 wherein said transducer signal is time dependent and said test function is a function of the time dependence of said transducer signal.
5. A machine tool system as described in claim 3 wherein said test function generating means comprises inte-grating means for generating an output proportional to the time integral of said transducer signal amplitude over the time period of each repetitive machine tool operation.
6. A machine tool system as described in claim 5 further comprising means producing a synchronizing pulse at the same point in each repetitive machine tool operation, said synchronizing pulse resetting said integrating means once during each repetitive machine tool operation.
7. A machine tool system as described in claim 6 further comprising a variable gain amplifier connected between said transducer and said integrator.
45,361
45,361
8. A machine tool system as described in claim 7 wherein said reference function generating means comprises sequencing means for varying the gain of said amplifier during normal operation of said machine tool to cause the output of said integrating means at the time a synchronizing pulse is produced to be substantially equal to an arbitrary setpoint level.
9. A machine tool system as described in claim 3 wherein said transducer comprises a piezoelectric accelero-meter.
10. A machine tool system as described in claim 3 wherein said transducer comprises a microphone.
11. A system for controlling a machine tool per-forming repetitive operation, said system comprising:
a transducer adapted to be mounted in association with a machine tool, said transducer constructed to produce a signal in response to mechanical impulses developed by operation of an associated machine tool; and means for generating a test function which is a function of the amplitude of said transducer signals and also a function of time;
means for automatically generating a reference function representative of said test function evaluated during normal operation of said machine tool; and means comparing said test function with said reference function and generating a control signal for controlling operation of said machine tool when said test function and said reference function differ by more than a predetermined amount.
a transducer adapted to be mounted in association with a machine tool, said transducer constructed to produce a signal in response to mechanical impulses developed by operation of an associated machine tool; and means for generating a test function which is a function of the amplitude of said transducer signals and also a function of time;
means for automatically generating a reference function representative of said test function evaluated during normal operation of said machine tool; and means comparing said test function with said reference function and generating a control signal for controlling operation of said machine tool when said test function and said reference function differ by more than a predetermined amount.
12. A system for controlling a machine tool as described in claim 11 wherein said test function is evaluated for each repetitive operation of an associated machine tool.
13. A system for controlling a machine tool, said system comprising:
a transducer adapted to be mounted in association with a machine tool, said transducer constructed to produce a signal in response to mechanical impulses developed by operation of an associated machine tool;
means for generating a test function which is a function of the amplitude of said transducer signals, said test function also being a function of time;
means for generating a reference function represen-tative of said test function evaluated during normal operation of said machine tool; and means comparing said test function with said reference function and generating a control signal for con-trolling operation of said machine tool when said test function and said reference function differ by more than a predetermined amount.
a transducer adapted to be mounted in association with a machine tool, said transducer constructed to produce a signal in response to mechanical impulses developed by operation of an associated machine tool;
means for generating a test function which is a function of the amplitude of said transducer signals, said test function also being a function of time;
means for generating a reference function represen-tative of said test function evaluated during normal operation of said machine tool; and means comparing said test function with said reference function and generating a control signal for con-trolling operation of said machine tool when said test function and said reference function differ by more than a predetermined amount.
14. A machine tool system as described in claim 13 wherein said transducer signal amplitude is time dependent, and said test function is a function of the time dependence of said transducer signal amplitude.
15. A system as recited in claim 13 comprising first control means for initiating the automatic generation of said reference function.
16. A system as recited in claim 15 comprising first indicating means for indicating that said system is in the process of automatically generating said reference function.
17. A system as recited in claim 16 comprising second indicating means for indicating that said reference function has been generated, that said test function is being generated for each repetitive machine tool operation, that said test and reference function are being compared, and that alarm and control action will be preferred when-ever said test and reference functions differ by more than a predetermined amount.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/542,315 US4023044A (en) | 1975-01-20 | 1975-01-20 | Automatic machine tool including a monitoring system |
| US542,315 | 1983-10-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1125891A true CA1125891A (en) | 1982-06-15 |
Family
ID=24163281
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA243,688A Expired CA1125891A (en) | 1975-01-20 | 1976-01-16 | Automatic machine tool including a monitoring system |
Country Status (13)
| Country | Link |
|---|---|
| US (2) | US4023044A (en) |
| JP (1) | JPS5939240B2 (en) |
| BE (1) | BE837711A (en) |
| BR (1) | BR7600241A (en) |
| CA (1) | CA1125891A (en) |
| CH (1) | CH602273A5 (en) |
| DE (1) | DE2600680A1 (en) |
| ES (1) | ES444479A1 (en) |
| FR (1) | FR2297692A1 (en) |
| GB (1) | GB1511942A (en) |
| IT (1) | IT1056685B (en) |
| SE (1) | SE430005B (en) |
| ZA (1) | ZA758065B (en) |
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| JPS54141472A (en) * | 1978-04-26 | 1979-11-02 | Fanuc Ltd | System for detecting tool abrasion |
| DE2844347C2 (en) * | 1978-10-11 | 1982-05-19 | Kaltenbach & Voigt Gmbh & Co, 7950 Biberach | Storage device for tools |
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| DE3241063A1 (en) * | 1982-11-06 | 1984-05-10 | Siegfried Ing.(grad.) 7321 Börtlingen Schwarz | Method and device for monitoring the forces on a punching press or the like |
| US4554534A (en) * | 1983-02-22 | 1985-11-19 | Helm Instrument Company | Control circuit for a multi-blow forming process |
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-
1975
- 1975-01-20 US US05/542,315 patent/US4023044A/en not_active Expired - Lifetime
- 1975-12-30 ZA ZA00758065A patent/ZA758065B/en unknown
-
1976
- 1976-01-09 DE DE19762600680 patent/DE2600680A1/en not_active Withdrawn
- 1976-01-12 GB GB990/76A patent/GB1511942A/en not_active Expired
- 1976-01-15 CH CH46976A patent/CH602273A5/xx not_active IP Right Cessation
- 1976-01-16 BR BR7600241A patent/BR7600241A/en unknown
- 1976-01-16 CA CA243,688A patent/CA1125891A/en not_active Expired
- 1976-01-19 IT IT41505/76A patent/IT1056685B/en active
- 1976-01-19 FR FR7601262A patent/FR2297692A1/en active Granted
- 1976-01-20 BE BE163627A patent/BE837711A/en unknown
- 1976-01-20 JP JP51004656A patent/JPS5939240B2/en not_active Expired
- 1976-01-20 SE SE7600521A patent/SE430005B/en not_active IP Right Cessation
- 1976-01-20 ES ES444479A patent/ES444479A1/en not_active Expired
- 1976-09-14 US US05/723,254 patent/US4088899A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| ES444479A1 (en) | 1977-09-16 |
| AU1014476A (en) | 1977-07-14 |
| IT1056685B (en) | 1982-02-20 |
| CH602273A5 (en) | 1978-07-31 |
| JPS5939240B2 (en) | 1984-09-21 |
| US4088899A (en) | 1978-05-09 |
| BR7600241A (en) | 1976-08-31 |
| FR2297692A1 (en) | 1976-08-13 |
| ZA758065B (en) | 1976-12-29 |
| SE7600521L (en) | 1976-07-21 |
| SE430005B (en) | 1983-10-10 |
| FR2297692B1 (en) | 1980-04-04 |
| JPS5197075A (en) | 1976-08-26 |
| DE2600680A1 (en) | 1976-07-22 |
| GB1511942A (en) | 1978-05-24 |
| US4023044A (en) | 1977-05-10 |
| BE837711A (en) | 1976-07-20 |
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