US3803768A

US3803768A - Control for movement of a device through successive ranges

Info

Publication number: US3803768A
Application number: US00181539A
Authority: US
Inventors: A Littwin
Original assignee: A Littwin
Current assignee: LITTWIN DONALD F; LITTWIN MARGARET C
Priority date: 1971-09-17
Filing date: 1971-09-17
Publication date: 1974-04-16
Anticipated expiration: 1991-04-16
Also published as: DE2245758A1

Abstract

Control for a machine having an advanceable part, such as a grinder having a grinding head which is advanced against a workpiece, the control being operative for automatically advancing the grinding head through a series of ranges according to a predetermined pattern, and thereafter completing a cycle and resetting the machine for a next cycle.

Description

United States Patent [19'] Littwin [451 Apr. 16, 1974 CONTROL FOR MOVEMENT OF A DEVICE THROUGH SUCCESSIVE RANGES [76] Inventor: Arthur K. Littwin, 6555 N0. Lemai,

Lincolnwoo d, 111. 60646 22 Filed: Sept. 17, '1971 [21] Appl. No.: 181,539

[52] US. Cl. ..L 51/93, 5l/l65.75 [51] Int. Cl. B24b 41/02, B24b 41/10 [58] Field of Search 51/92 R, 93, 45, 165.75,

[56] References Cited .UNlTED STATES PATENTS 3,474,573 10/l969' no e e'ri; 51 9211 3,045,165 7/1962 Littwin ..s1/231x Wilson 51/92 R 2,486,108 10/ l 949 Brunel 2,859,564 11/1958 Farmer 2,390,978 12/1945 Woodbury 2,927,403 3/1960 Holland 51/233 X Primary ExaminerDonald G. Kelly Attorney, Agent, or Firm-Paul H. Gallagher [57] ABSTRACT Control for a machine having an advanceable part, such as a grinder having a grinding head which is advanced against a workpiece, the control being operative for automatically advancing the grinding head through a series of ranges according to a predetermined pattern, and thereafter completingva cycle and resetting the machine for a next cycle.

17 Claims, 14 Drawing Figures PATENTEUAPR 16 I974 SHEET 1 [1F 8 PATENTEDAPR is m v SHEET 2 UF 8 in u v 16 MANUAL y L@ I SPEED ADI INCRAI'IENTAL FEED ADI- I 1. o M We RANGE 2NDRAN5E ISTRANGE ZNDRAusE RETURN Q Q o o o O Hl CONTROL FOR MOVEMENT OF A DEVICE THROUGH SUCCESSIVE RANGES CROSS REFERENCES:

The following U. S. patents and applications for patents may be referred to, in which certain features incorporated in the apparatus of the present invention are described and claimed: I

July I7, 1962 Patent No. 3,045,l65 Littwin Patent No. 3,247,434 Littwin April l9, I966 Patent No. 3,136,2l6 Littwin June 9, 1964 Patent No. 3,246,569 Littwin April I9, 1966 Patent No. 3,573,586 Littwin April 6, i971 Patent-No. 3,360,694 Littwin Dec. 26, 1967 Patent No. 3,588,65l Littwin June 28, i971 OBJECTS OF THE INVENTiON:

A broad object of the invention is toprovide control apparatus for a machine having a movable part whereby to control movement of that part, particularly in advancing direction, in a series of steps or ranges according to a predetermined setting or pattern of operation. I

Another broad object is to provide a control apparatus of the kind just previously referred to wherein the steps or ranges of movement of the part can be adjustably set according to different degrees or amounts of movement according to an amount of work to be done, suchv as grinding material from a workpiece.

Still another object is to provide control apparatus of the character just referred to, wherein the degrees of movement of the part, whichmay be a grinder head, can be moved in successively different extents, such as successively lesser extents whereby the grinder head may be used for first removing substantial quantities of material from the workpiece, and thereafter used for removing lesser quantities in a dressing operation.

Still another object is to provide control apparatus of the foregoing general character which involves components of adjustments of both uniform time anduniform speed whereby to more accuratelycontrol the effect of ble to machines such as grinders, in which material is removed from a workpiece, first in substantial quantities, and then in lesser quantities in a dressing operation,and further wherein the stepsor phases of that kind of operation are pre-set according to a predetermined pattern, and still further in which that pattern may be interrrupted by the operator of the machine to apply other operating steps independent of the present apparatus, such as an in-process gauging step to'determine the actual progress on the work on the workpiece, independently of the predetermined setting of theapparatus. i

Another and important object of the invention is to provide a novel remote control arrangement for controlling the foregoing steps, and the various components involved in effecting those steps, from a single remote control station. 7

A further object is to provide, in an apparatus of the foregoing character, novel drive means for effecting the desired differential rates of movement in the different stages of the operation.

Still another object is to provide a novel control means whereby the movable part is moved or advanced in successive stages, and including novel clutch means which at each station performs a clutching operation before release of the previous clutching operation.

, Still another object is to provide apparatus of the foregoing general character which includes a clutching and driving means of such novel design as to enable its incorporation in a compact unit whereby it can be cmbodied in a grinder of construction known'heretofore, and whereby to minimize reconstruction of a grinding machine that has been heretofore used, thereby minimizing costs in adapting the apparatus of the present invention to machines heretofore in use.

Still another object is to provide a control apparatus of the foregoing character wherein the movable part of the machine is advanced toward the workpiece in a series of steps or ranges, and wherein the control apparatus is operative for stopping the advancement of the movable piece, and holding it in the position in which it was stopped, and wherein it-can be again moved and advanced according to the predetermined pattern of advancement of the part-after the stopping operation, and as a continuation of the advancement of the part before and after the stopping operation.

Another object of the invention is to provide a novel control apparatus of the foregoing character whereby the advancement of the movable part toward the workpiece can be controlled through an automatic reaction operation in which for example if the movable part should be advanced toward the'workpiece at too great a rate of advancement, the reaction between the advanced part and the workpiece which would be occasioned bythe greater power required because of the greater advancement, would produce a greater drain on the current, which is utilized in slightly retracting the workpiece to a position which was predetermined for removing the desired amountof material from the workpiece.

A still further object is to provide a novel arrangement in which the movable part, such as a grinding wheel, can be returned to its initial position in a rapid movement irrespective of the degree of advancement thereof, whether in early stages for removing a great amount of material, or in later stages for removing a lesser amount of material in dressing operations.

Still another object of the invention is to provide in a control apparatus of the foregoing character as applied to a machine such as a grinder, which incorporates a clutch for advancing the movable parts such as the grinder wheel, and wherein in the event of failure of the clutch, the control means automatically shuts off, thereby providing a safety feature.

An additional object is to provide a control apparatus of the foregoing general character including a manual control arrangement whereby an operator can move the advanceable part against the workpiece at a controlled and desired rate, and upon reaction of the movable part against the workpiece, in the action of advancing the movable part, if it is found that the advanceable part is advanced at too great a rate, the operator can in the midst of the manual operation diminish or reduce the rate of advancement according to the apparent reaction (as by amount of spark) of the advanceable part against the workpiece, whereby the operator can completely control, under manual operation, the advancement of the movable part according to the result to be achieved.

DESCRIPTION OF A PREFERRED EMBODIMENT:

In the drawings:

FIG. I is a perspective view ofa grinder to which the present invention is applied, showing certain parts in section;

FIG. 2 is a semi-diagrammatic view, taken from the side of the grinder, showing the table, and indication of the reciprocating movements of the table, in longitudinal direction and the means for controlling such reciprocating movements;

FIG. 3 is a semi-diagrammatic view of the table similar in all respects in FIG. 2, but indicating the movements of the table in transverse directions;

FIG. 4 is a face view of a control panel of the machine in general, indicated by the numeral 4 in FIG. 1',

FIG. 5 is a pe spective view of a contrgl ele mgnt in the form of a micrometer, utilized for controlling the operating movements of the apparatus;

FIG. 6 is a top view of the down feed drive assembly;

FIG. 7 is an electional view including certain detail components of the clutch means of FIG. 6, oriented according to line 77 of FIG. 6;

FIG. 8 is a perspective view of a compact unified arrangement of down feed assembly adapted for incorporation in a compact drawer arrangement for incorporation in a pre-existing machine;

FIG. 9 including 3 parts 9a, 9b, 9c together form a circuit diagram of the main electrical control of the apparatus;

FIG. 10 is a circuit diagram of one part of the electrical control embodied in the apparatus;

FIG. 1 1 is a circuit diagram of one part of the electrical control embodied in the apparatus; and

FIG. 12 is a circuit diagram of one part of the electrical control embodied in the apparatus.

For an explanation of the general purpose of the apparatus of the invention, attention is directed to my prior US. Pat. No. 3,573,586, referred to above, which briefly is to control a tool, such as a grinding wheel, to move it into engagement with a workpiece for removing material, or metal, from the workpiece, first in large quantities and then in small quantities in a dressing operation, all according to a predetermined set pattern of operation. I

Referring in detail to the accompanying drawings, attention is directed first principally to FIGS. 1-8 showing the pertinent mechanical features. Certain of the elements of these figures are also represented in the main circuit diagram of FIG. 9, a full description of that circuit being given hereinbelow. For convenience in locating the various elements in the main circuit of FIGS. 9a, 9b, 9c, the diagram is provided with co-ordinates on the margins, utilized in the description below to indicate the locations of the elements.

In the circuit of FIG. 9, certain components include elements at different locations in the circuit; these components are identified by general reference numerals, and the separate elements identified by the same reference numerals with subscripts a, b, 0, etc.

FIG. 1 shows a machine to which the invention is particularly adapted, this machine being a grinder. The

machine includes a base 22 and a table 24 which is reciprocable in each of two directions, longitudinally and transversely, as referred to again hereinbelow. The table 24 is provided with an electromagnetic chuck (not shown) which holds a workpiece 26 for performing a grinding operation thereon by a tool head or grinding wheel 28 brought into engagement with the workpiece. The grinding wheel 28 is mounted in a downfeed drive assembly 30 mounted in an upright column 32 in the machine and vertically slidable in a slot 34 in the upright column. The grinding wheel 28 is mounted on a shaft 36 driven by a motor 38.

The assembly 30 is moved up and down by a feed screw 40 having one end rotatably mounted in the assembly 30 and threaded in the column 32 of the frame of the machine.

The table 24 may be driven in reciprocating movements by any suitable means, such as a motor 37 and as referred to in my prior US. Pat. No. 3,045,l65, re-

ferred to above. Attention is directed to FIGS. 2 and 3 showing control elements for controlling the table. In FIG. 2 the table is shown provided with a taper bar 25 extending longitudinally and against which a follower 27 bears, and pursuant to longitudinal reciprocation of the table the follower 27 moves cores 3] into and out of corresponding coils 33 for controlling the movements of the table as described and claimed in the patent just referred to. FIG. 3 indicates reciprocation of the table in transverse directions, having a taper bar 35 and a follower 37 operating in the manner referred to in connection with transverse reciprocations. In the grinding operation, the table reciprocates with the grinding wheel 28 in engagement with the workpiece for performing the desired grinding operation, in a known manner. It is also possible to mount the grinding wheel for reciprocation in axial directions, but in the present construction it is desired that the corresponding reciprocations be accomplished by mounting the grinding wheel in axially stationary position, and reciprocating the workpiece.

The downfeed drive assembly 30 constitutes an important feature of the invention and the following is a description of the mechanical construction thereof (FIGS. 1, 6 and 7). The unit 30 includes a reversible two-speed motor 42 and a drive transmission unit 44; it also includes an output shaft 46 having a miter gear 48 thereon in mesh with a miter gear 50 secured to the lower end of the threaded shaft 40. Upon operation of the motor 42, drive is transmitted to the gear 50, and thus the shaft 40, for'raising or lowering the entire downfeed drive assembly 30. As indicated above, all of the

elements

28, 38, 42, 44 and 50 are mounted for conjoint vertical movements, the assembly including a unitary frame 52 on which those elements are mounted.

Referring to FIGS. 6 and 7, the motor 42 has a drive shaft 54 on one end of which is a pulley 56; the drive transmitting unit 44 includes an output shaft 58 on which is a pulley 60, and a belt 62 is trained on the

pulleys

56, 60; the shaft 58 also includes a pulley 64 which through a belt 66 drives another pulley 68 on a shaft 70 in the assembly. Finally another pulley 72 is mounted on the shaft 70 and the latter pulley through a belt 74 drives a pulley 76 on the output shaft 46 for driving the feed screw 40.

The shaft 54 of the motor 42 also extends through the opposite end where a pulley 78 is provided on which is trained a belt 80 also trained on another pulley 82. The pulley 82 drives a speed reduction gearing 84 which may include two worm gear units. The output of the gearing 84 includes a shaft 86 leading to an auto feed clutch 88 of known kind having a clutch plate 90 electrically controlled, which is turn controls a drive transmitting unit 94 and thereby controls the drive of the pulley 68 and consequently the

gears

48, 50 and screw shaft 40.

The drive transmitting unit 44 also includes a power elevation clutch 96, and a dress clutch.98 operating through a shaft 100-which in turn controls the operation of control units or

transducers

102 and 104, as by means of cams 105, 107 (FIG. 9, F-ll, 12). As will be referred to in the description of the main circuit of FIG. 9, the

units

102, 104 each include a core 101 and a coil 103 as described in connection with my US. Pat. No. 3,041 ,165, referred to above. Also attention is directed to my prior U.S. Pat. No. 3,136,216, referred to above for a suitable means for driving the

cams

105, 107, producing even advancement thereof, and without play or slack.

Upon energization of the clutch means 88, the drive is transmitted from the motor 42 to the screw shaft 40, and upon energization of clutch 96 or clutch 98, the drive is transmitted from the motor 42 through the gearing 84 to the

corresponding control unit

102, 104 for moving the cores therein, as described belowin connection with the circuit of FIG. 9.

In moving the drive unit 30 down, in the first part of that movement, the

transducers

102, 104 are carried therewith without movement relative in the drive unit, but after the drive unit is adjacent the workpiece, they are moved relative to the drive unit.

The machine of FIG. 1 includes a remote control unit 106 shown in detail in FIG. 4. This control unit includes a number of control components, but particularly a plurality of (three) micrometer adjustment units 108 individually identified 108a, 108b, 108c. Each unit 108 includes a body 110 (FIG. 5) fixedly mounted in position and a rotating barrel 112. Each micrometer unit also includes a control unit or transducer 114, individually identified 114a, 114b, 1140, these units also appearing in the electrical circuit of FIG. 9 (G-7). These control units, as referred to again hereinbelow are of the kind described and claimed in my US. Pat. No. 3,045,165, referred to above. The unit114 includes a core 116 working in a coil 118, and upon adjustment of the barrel 112 the core 116 is moved relative to the coil. As described in my US. Pat. No. 3,573,586, referred to above, the micrometer transducers are adjusted according to the amount of metal to be removed from the workpiece, and when that point is reached,

A opposing voltage inthe transducers 114 and the

transducers

102, 104 terminate the operation (see below).

In reference to the main circuit of FIG. 9, when relay 120 (E'l5) is de-energized it closes a circuit to the rotor 122a (l -16) of a stepper switch 122, moving the position to the third range as shown by l22b (J-) the relay 120 makes a contact closure to the initiating relay. When relay 124 (B-9) is energized, relay 126 (E-15) is energized, which automatically energizes gage reset relay 128 (D-15) which re-sets relay 124, tie-energizes the auxiliary gage reset relay 128 which in turn re-sets relay 124, de-energizing relay 126, closing a circuit energizing the stepper rotor 122a (I16) moving it to the fourth position and the same time closing a contact for energizing the sizing downfeed control 130 (C-10) shown in detail in FIG. 12, re-energizing the relay 124. Relays 132 and 134 (E-16) are energized. Relay 136 (H-15) is de-energized at the start of the fourth cycle; relay 138 (B-16) is energized by the power elevation clutch 96 (C-16) at the start of the fourth cycle, i.e., at the completion of the second range, the third range is by-passed when the node switch 140 (C-10) is set in that selected position. The first and second range transducers 114a, 1.14b (G-7) disconnected from the circuit as well as the first and second range transducer 102 (G-ll), and the setting is now in the fourth range with the stepper rotor 122a (l-16) connected to the return micrometer transducer 114C and the return traverse coil 104 (G-l 1 The rotor circuit-can be maintained closed through the rotor, and through a transistor circuit 142 (l-lS) automatically disconnecting the rotor even though the voltage is applied through a contact closure, this eliminating burning out rotors which are not designed to be left on continuously, and makes a circuit arrangement for a positive action and a safety feature of disconnecting the rotor even through the voltage is applied, as when a relay contact is defective and keep the circuit closed, or if in the original installation, it should be wired incorrectly and hold that circuit closed.

The traverse clutch 144 (G46) is energized at the start of the fourth range relay 146 (1 -16); the return traverse transducer 104 (G42) and the return micrometer transducer 114C (6-9) are energized, and after the spark out and closure of circuit at terminal 148 and 150 (B-14), the relay 138 (A-16) is energized and at that time the motor 42 (J-2) accelerates to a maximum speed; it continues to run until the setting of the return transducer 1140 is reached, and at that time the motor de-celerates; the decelerator adjustment is included in the downfeed speed control 151 (H-14), the details of which are included in FIG. 11. When the rotor 122a (l-l6) is energized it moves the stepper to the fourth position, and all circuits are closed including the circuit of the return micrometer transducer 1140.

The de-celerator includes a unique feature that is incorporated in the unit 151 speed control and is wired to terminals 152 (l-3) of the motor speed control; the voltage that is fed into terminals 152, 154 is derived across

terminals

156, 158, (I2) of the unit 151; the voltage is then fed into a transformer in the unit 151 which is rectified and put into the positive biasing of the unit. When that voltage is at maximum it offers full speed control and as the core in the return transducer 104 (G-12) is matched to that of the return micrometer transducer 1140, the voltage across 152 and 154 reaches a null or a zero point, and at that time the speed of the motor is gradually changed to where the return potentiometer (I-S) takes over and runs the motor at a speed pre-set by this return potentiometer. With this feature, the motor is able town at maximum speed until it reaches the point of positioning, and then it gradually de-celerates to where it runs at the speed setting of the potentiometer and eliminates excessive overrun and provides accurate positioning.

In the base setting of the return range transducer 1140, (6-18) the motor will continue to run at this speed setting until the unit 130 (B-10) is signalled to de-energize relay 124 (A-9), which is done when the coil 102 (G-11) in the traverse of the transmission drive is nulled with that of the return coil 114c micrometer setting. When relay 124 is de-energized, relays 132, 134, (E-) are de-energized, the traverse clutch 144 (G-16) is de-energized, relay 146 (F15) is de-energized and relay 138 (8-16) is de-energized, relay 146 ((F-15) is de-energized and relay 138 (B-16) is de-energized; this is the completion of the fourth and return range, and the red manual light 162 (G-9) glows. The foregoing concludes a complete sequence of operation in the No. 1 setting of the mode switch 140 (C-10), including first and second ranges of sizing according to the settings of the units 1140 and 114b, (G-7) and return range according to the setting of the unit 1140. A third" range is indicated at 164 (I- 13); this provides great versatility, in that the sequence of operation can be manually interrupted by the operator to enable an in-process gauging step, i.e., to check the actual size of the workpiece, and then the grinding operation can again be set in motion again. This checking can be done by initiating the third range 164.

Reference is made to FIG. 12 for the content of the unit 130. This unit is described and claimed in my prior U.S. Pat. No. 3,588,651, referred to above but a brief description is given here for convenience. Transformer 170 (top) is energized, which energizes all secondaries 17081, 17082, 170S3; winding 17051 is 18 volts and used for rectification filtering for a zener-r'egulated positive bias supply for turning out the triggering dial 171 and operating transformer 172; the winding 17082 is 36 volts, which is rectified, filtered and zenerregulated for providing a regulated voltage for the amplifier transistor 174. The transformer winding 170S3 is a 12 volt center tapped winding, and is used for furnishing voltage to the primary windings of coils first range, second range, and return range transducer 114 (FIG. 12, bottom and FIG. 9, G-7) and first, second range, and return range, transducers 102, 104 (FIG. 12, bottom and 6-11, 12); the 12 volt winding 17083 is also used to furnish voltage to the

intercompensator transformers

176 and 178 which have their windings in series, the center tap 180 thereof running to terminal No. 6, 182 which is fed to the common of the primaries of the transducer coils (See also FIG. 9, G-7 to 12); the voltage variation affects the voltage on the primaries of the

transformers

176 and 178 for the purpose of offsetting the bias to the amplifier circuit to compensate for temperature variations in either

transducer unit

102, 104, or the micrometer transducers 114. The voltage output of each of the transducer coils which are connected in series is rectified and filtered and its output is connected in series with the temperature compensating output and is fed to the amplifier transistor 174. The output from the amplifier transistor is fed in series with the bias of the differential adjustment through the SCR 171. To energize relay 124 (FIG. 12, upper left, FIG. 9, 3-9), a contact closure of terminal 294 (C-8) of relay 124 turns on transformer 184 through the SCR 171; this energizes the secondary of transformer 184 which turns on the 186 transistor circuit for firing the relay 124 when the null point of the transducers is reached and the control is signalled to de-energize; the positive bias of the SCR 171 is increased to a point where it fires, turning on transformer 172 which nulls the voltage of 184, de-energizing the transistor 186 firing circuit to 124, and the latter is de-energized.

Reference is now made to automatic impulsing index timer 190, FIG. 9, (F4), and shown in FIG. 10. This component is described and claimed in my prior patent No. 3,360,694, referred to above, but a brief description is given here for convenience. Voltage (l 15 volts) is applied to terminals 192 and 194, energizing the transformer 196. The upper portion across of the circuit of FIG. 10 including the primary 196P is utilized for the automatic impulsing circuit for

relays

198 and 200. Closure of terminals 192 to terminal 202 or terminal 204 energizes either relay 198 or 200; these act as a filtered capacitor for sustaining the voltage across either relay when the circuit is open, so that 198, for example, would remain energized for a short duration after 200 is energized. The fact that these are both energized, pole No. 1 of each relay automatically impulses relay 206 across

terminals

208 and 210. This occurs at each contact closure of breaking at 202 and making at 204 or breaking at 204 and making at 202, depending upon the direction that the limit switch is actuated. 9

In the center portion of FIG. 10 the secondary 196S applies volts for the purpose of operating relay 206 through the SCR 212, which is triggered by a transformer 214 and SCR 200; when an automatic impulse is given through the contacts of 200 or 198, relay 206 is energized through diode 216. The SCR 218 has a positive bias and when relay contact 206b is closed, transformer 214 has a maintained voltage through SCR 218, and the automatic impulsing circuit may be opened through diode 216, but the relay 206 will remain energized through conduction of SCR 212 which has its gate turned on through the transformer 214. When relay 206 is energized, contact 2066 opens the circuit to the capacitor 220 which begins to diminish the positive bias, which decays; the negative opposing bias set up by the potentiometer 222 across the

terminals

224, 226, 228 opposes the decaying of the positive bias of the capacitor 220 and when this decays to the point where the negative bias takes over, SCR 218 deenergizes; the bridge thermister circuit 230 is used as a temperature compensating circuit; when the SCR 218 heats from the ambient temperatures, the bridge balances to reduce the positive bias.

Referring to FIG. 9a voltage is applied to the single phase AC supply at 232 (A-6) and energizes the master stop relay 233; this will energize the primaries of the 500 volt ampere control transformer 234 (A-2) and auxiliary control transformer 236 (A-11); if a selector relay or switch is not used, jumpers may be replaced between terminals 238 and 240 (H-l), 242 and 244 (8-7), 246 and 248 (J-3, B-13) 150 volt DC will be applied to the shunt field of the motor from terminals 250 and 252 (I-3) of the motor speed control 151 and to terminals 248, 254 (J-3). The auxiliary transformer 236 (Al 1) isolates the motor control circuit which offers the greatest power consumption to eliminate feedbacks or transient type surging into the sizing circuit. The control (C-10) gets its signal from the micrometer transducers 114 (G-7) and the sizing traverse tranducers 102, 104 (G-11, 12) in the drive assembly.

For manual power elevation of the control, press either the raise pushbutton 256 (A-15), or the lower pushbutton 258 (C-14); when pressing the raise pushbutton, the drive assembly will offer accelerated speed to maximum setting without any variable control means, this being accomplished in the control 151 (H-3). In this connection attention is called to FIG. 11 which includes the content of this control. The subject matter thereof is described and claimed in my prior US. Pat. Nos. 3,564,292, and 3,588,651, referred to above, but a brief description is given here for convenience. There is a normally closed contact defined as external high speed reversing relay 260; when the circuit from the potentiometer 262 controlling the motor speed to the terminal 264 is opened, this offers a full positive bias and the motor speed control is directed at high speed after the acceleration period takes place through closing a circuit from

terminals

266 and 268. Normally closed contact l38b FIG. 9 (J-l) runs from terminal 156 (I-2) of the motor speed control through 138c (.l-6), normally closed, to terminal 270 (l-2) to the manual speed potentiometer 272 (I-9). Referring again to the sequence of the operation, when the lower pushbutton 258 (C-14) is pressed, the power drive assembly will offer variable speed control of the elevating screw 40 by means of the manual dial setting; when the raise pushbutton 256 (A-l4) is pressed, relay 138 is energized and when the lower pushbutton is pressed, relay 274 (13-16) is energized. At this point the contact 138d (13-15) energizes the power elevation clutch 96 (C-16) and also closes the circuit from terminals 266 and 268 (1-2) of the power elevation and downfeed speed control; the motor then accelerates through these terminals and reaches maximum speed as long as the raise pushbutton is pressed. When the lower pushbutton is pressed, relay 274 is energized and the power elevation clutch is also energized through contact274b (.I-l and the accelerating circuit of terminals 266 and 268 (1-2) is also closed throughcontact 274d (1-2); the motor accelerates but runs at 'a speed in accordance with the setting of the manual potentiometer 272 (I-9) of which the circuits are closed through the normally closed contacts 132b, 1320, and 136b, 136c. Relay 136 (H-1 5) is the cycle start relay and since the apparatus is in themanual position, it is tie-energized. Referring to the control 151 (H-3) when a contact closure is made across 266 and 268, these terminals'also appearing in FIG. 11 (lower right), this lay-passes the capacitor 276 which supplies the negative bias to the transistor 278 which then starts to slowly conduct to a maximum conduction which offers a bias supply across the resistor 280 for furnishing a positive bias to the firing circuit 282. The transistor 284 used in the speed control and voltage feedback circuit will conduct in accordance with the setting of the potentiometer 262; the motor 42 is furnished with a constant voltage .on the field but a variable voltage on the armature through

SCRs

288 and 290. v

If the apparatus is in auto cycle position and it is'desired to raise the power elevating screw 40, the operator need only press the raise pushbutton 256 (B-l4) and the automatic'range will be disconnected and the power elevating screw raised immediately at maximum speed, regardless whether the apparatus is in automatic position, any time the raise pushbutton is pressed, the automatic operation is disconnected, and the screw is power-elevated as described previously, by closing a circuit across

terminals

266 and 268 and opening a circuit through contact 138a (J-6) of the manual potentiometer.

In the auto cycle operation, the auto cycle start button 299 (-9) is pressed, the first range pilot light 292 (F-9) is lighted and relay 136 (H-lS) is energized, the latter setting up the cycle by a contact closure across terminal 294 (8-8) through normally closed contacts l29b (D-9), 120b, 126b, and 132b, to terminal 296 (C-l0), through either the inprocess gage contact 298, normally closed, to terminal 300 (C-l0, A-14) or the mode switch 140a back through the raise pushbutton terminal 300 (A-14), through terminal 302 (A-14) back to the on-off switch 304a (B-7) to terminal 242 and the auxiliary transformer-236. Turn the first range micrometer transducer 114a (G-7) and the core moving in and out of the coil buildsa voltage on the secondary, which is impressed into the circuit of the control 130 (C-l0, and FIG. 12 top right); this is a positive bias and is series-connected through the stepper circuits to the traverse transducer 102 (G-l 1 and they form an opposing voltage. A null point is found between the

transducers

114a and 102, and at this point, the transformer 172 (FIG. 12) is energized by the SCR 171 and it nulls out 184. This procedure should be followed for each range. When the auto cycle start pushbutton 299 (F-9) is released, the control circuit 130 (C-10) will be closed for operation; the relay 124 (13-9) will be energized and retained with the auxiliary gauge reset relay 128 D-15) de-energized; the traverse clutch 144 (G-l6) will be energized and relay 146 (F-lS) will be energized' Relay 129 (D-15) of the first range will be energized; relay 274 (8-16) will be energized, turning on the motor 42 (J -2).' The motor will run at a speed rate set by first range incremental dial,305 (H-7), which will not only adjust the speed of the DC motor through the speed control 151 (11-4), but it adjusts the time rateof the downfeed index timer 190 (E-4); the potentiometer circuits are wired across the terminals 306, 308, 310 of the timer 190; by pressing the lower pushbutton 258 (8-14), a continuous pulse will be sent to the auto impulse timcr which in turn will energize the auto feed clutch 88 (F-l6); the elevating screw will be pulsed in accordance with the setting of the incremental dial or fed continuously as long as the lower pushbutton is held.

At each table reversal an automatic impulse will be set up by the control 190 (E-4) through the closure of machine relay 312 (C-4) or 314 (C-1) to terminals j the table 24 at each reversal; at each table reversal an impulse will be given to the auto feed clutch 88 (F-16) in accordance with the incremental dial setting, e.g., 305 (H-7) of each range; with the traverse control clutch 144 (G-16) energized. during the downfeed range, as an incremental feed pulse is given to the elevating screw, an impulse is also directed through the traverse control clutch to the traverse transducers 102, 104 (G-l2). Consequently as the screw is turned, it is fed back through the traverse clutch 144 through the gearing'to the first and second range transducer 102 (G-ll moving the core out toward the setting of the first range micrometer dial adjustment; after a number of impulses, when the desired stock removal is obtained by setting of the first range micrometer transducer 1 14a (G-7), the traverse tranducer reaches the desired setting of the remote control micrometer, and the control (G-10) is signaled to de-energize relay 124 (B-9), and at that time the first range relay 129 (D-lS) is de-energized; the safety relay 146 (F-lS) and traverse clutch 144 (G-l6) are de-energized; relay 131 (D-lS) is energized which energizes the dress clutch 198 (6-16) the relay 131 continues to hold contactor 8 when the first range relay 129 (D-15) is deenergized; the dress clutch holds the traverse tranducer 102 (6-11) of the first and second range in the exact position before the traverse clutch 144 (G-16) is deenergized, so that the second range may continue where the first range left off. The circuit was completed to the stepper rotor 122a (l-l6) moving into the second range; at the same time a circuit is completed initiating relay 124 (B9) and this is done through closure of contacts from terminal 314 (D-8) to terminal 296 (C-10); relay 124 retains itself for the second downfeed range; when relay 124 is energized for the second downfeed range, relay 120 (E-lS) is energized; relay 131 (D-lS) is de-energized; relay 146 (F-) is energized; and the traverse clutch 144 (G-16) is energized; the dress clutch 198 (G-l6) is de-energized but after the traverse clutch is energized. The motor then runs at a speed in accordance with the setting of the incremental dial 320 (H-9). At each table reversal, the circuit closure is made to the index timer 190 (13-4) which gives an impulse to the auto downfeed clutch 88 (F46) for a timed duration in accordance with the setting of the incremental dial 320 and at a speed in accordance with the setting of the control 151 (H-4).

FIG. 8 shows a convenient construction of the drive assembly 30. The motor 42 and the drive transmission unit are mounted on a drawer" 323 which can be easily put in place in an existing grinder, with a minimum of adaptation of the grinder.

I claim:

1. A machine comprising,

a table for holding a workpiece,

a drive assembly including a work head,

the table and the workpiece thereon being reciprocable longitudinally and transversely relative to the work head,

first electrical motor means for so reciprocating the table,

means mounting the drive assembly for vertical reciprocating movements relative to the table, second electric motor means for so reciprocating the drive assembly,

circuit means including the motor means,

voltage generating means operated by the table for controlling the first motor means for reversing the direction of reciprocation of the table in each the longitudinal and traverse directions, first control means remote from the table including manually manipulable members infinitely adjustable for predetermining the movements of the table to opposite limits in each of the longitudinal and transverse reciprocations, and

second control means remote from the drive assembly including a manually manipulable member infinitely adjustable for predetermining the extent of movement of the drive assembly toward the table and the workpiece thereon.

2. A machine according to claim 1 wherein the drive assembly is movable in a series of ranges toward the table and the workpiece thereon, and

the second control means includes a control element operable for predetermining the limits of each range of movement of the drive assembly,

each such control means including a micrometer device having a movable element and a core connected with the movable element working in a coil,

the core and the coil forming a transducer, the control means also including electrical control circuit for controlling the operation of the drive assembly in accordance with the ranges of movement to be produced, the electrical circuit including said coil and core and being responsive to the adjusted positions of such coil and core. 3. A machine according to claim 1 and including a feed screw threaded in a fixed portion of the machine and operatively connected with the drive assembly, the drive assembly including drive means and means for transmitting drive from the drive means to the feed screw, the drive means being operable for moving the entire drive assembly and the work head vertically down into engagement with, and up out of engagement with, the workpiece on the table, and control components operative for moving the drive assembly rapidly vertically when the work head is out of direct proximity to the workpiece, and for moving it downwardly in fine increments when the work head is in engagement with the workpiece. 4. A machine according to claim 3 wherein the rapid movements and the fine increment movements respectively constitute ranges of movments, the drive transmitting means includes a plurality of clutches, one clutch for each range of movement, and additional control means for independently and selectively energizing the clutches for effecting movement of the drive assembly at the respective corresponding rates related to the different clutches.

5. A machine according to claim 4 wherein the means for selectively energizing the different clutches includes means for retaining each clutch in holding condition until another clutch is moved into holding condition, whereby to eliminate gaps between holding conditions of the different clutches.

6. A machine according to claim 3 and including transducers each including a coil and a core movable therein,

the transducers including'a first set manually adjustable for controlling the movement of the drive assembly, and other transducers mounted in the drive assembly arranged for producing opposing voltage in the two sets, and

electrical means responsive to the voltage of the two sets of transducers, operative in response to a null point being achieved between the two sets of transducers for terminating movement of the drive assembly.

7. A machine according to claim 3 and including additional control means which in turn includes manually 5 settable elements mounted on the machine,

additional control elements mounted on the drive assembly and movable therewith, I

the additional control elements being carried bodily by the drive assembly, and

means also carried by the drive assembly for actuating and controlling the additional control elements in response to movement of the drive assembly through a predetermined range of movement, whereby to move the additional control elements relative to the main part of the drive assembly for effecting control functions of the work head.

8. A machine according to claim 3 and including,

manually settable control elements on the machine, control elements on the drive assembly movable with the drive assembly as the latter is moved toward and from the workpiece on the table,

clutch means for controlling the movement of the drive assembly toward and from the workpiece,

clutch means for controlling the movement of the control elements carried by the drive assembly, and

cluding a coil and a core movable in and relative to the coil, and the transducers in the control elements mounted on the machine and on the drive assembly respectively produce counteracting voltages, and the machine also including means responsive to the voltages produced, and to a null position between the-counteracting voltages, for controlling the movement of the drive assembly and the transducers in'the control elements on the drive assembly.

l0.A machine according to claim 3 and including means for establishing a plurality of ranges, each range representing an amount of movement of the drive assembly,

and means for interrupting the movements of the drive assembly in direction toward the workpiece,

and including means for gauging the dimension of the workpiece upon removal of the drive assembly from operating position, and

thereafter re-establishing the drive assembly in position relative to the workpiece in accuracy with its position before removal therefrom.

11. A machine according to claim 10 and including stepping switch means providing a plurality of stations, one for each of the ranges, and

means for advancing the stepping means pursuant to termination of each step for setting up circuit for the succeeding step.

12. A machine according to claim 1 and including stepping switch means having a rotor,

electrical circuit means including the rotor for advancing the rotor,

said electrical circuit means including transistor means preventing excessive current to the rotor beyond the capacity of the rotor whereby to prevent damage to the rotor beyond a predetermined pe-' riod of time. t

13. A machine according to claim 1 including manually manipulable means under manual control for moving the drive assembly downwardly into proximity to the workpiece,

the machine includes an electrical circuit for so moving the drive assembly downwardly including a pushbutton under manual control, and means responsive to actuation of the pushbutton for advancing the drive assembly and work head, and operative for continuously advancing the assembly and work head pursuant to continuous depression of the pushbutton, and also including means for so advancing the drive assembly and work head to a predetermined extent pursuant to momentary depression of the pushbutton.

14. A machine according to claim 1 wherein the advancement of the drive assembly and the rate of operation thereof are uniform both as to rate of movement and thereby rate of time passage.

15. A machine according to claim 1 including means for controlling the degree of advancement of the work head against the workpiece and means responsive to engagement of the work head with the workpiece beyond a predetermined amount of pressure for retracting the workpiece to within the predetermined pressure set therefor.

16. A machine according to claim 4 wherein the clutches are electrically controlled, and the machine including an electrical circuit for controlling the clutches, and the circuit includes additional means for locking the means for moving the drive assembly downwardly in the event of failure of the clutches, whereby to prevent the drive assembly from moving downwardly beyond a predetermined extent into engagement with the workpiece.

17. A machine according to claim 4 wherein the drive transmitting means includes rotatable means,

the drive assembly unit includes transducers for controlling an electrical circuit,

and the drive transmission means includes rotary elements operative for advancing the transducers in controlling movements according to the progress of the drive through the drive transmitting means.

Claims

1. A machine comprising, a table for holding a workpiece, a drive assembly including a work head, the table and the workpiece thereon being reciprocable longitudinally and transversely relative to the work head, first electrical motor means for so reciprocating the table, means mounting the drive assembly for vertical reciprocating movements relative to the table, second electric motor means for so reciprocating the drive assembly, circuit means including the motor means, voltage generating means operated by the table for controlling the first motor means for reversing the direction of reciprocation of the table in each the longitudinal and traverse directions, first control means remote from the table including manually manipulable members infinitely adjustable for predetermining the movements of the table to opposite limits in each of the longitudinal and transverse reciprocations, and second control means remote from the drive assembly including a manually manipulable member infinitely adjustable for predetermining the extent of movement of the drive assembly toward the table and the workpiece thereon.

2. A machine according to claim 1 wherein the drive assembly is movable in a series of ranges toward the table and the workpiece thereon, and the second control means includes a control element operable for predetermining the limits of each range of movement of the drive assembly, each such control means including a micrometer device having a movable element and a core connected with the movable element working in a coil, the core and the coil forming a transducer, the control means also including electrical control circuit for controlling the operation of the drive assembly in accordance with the ranges of movement to be produced, the electrical circuit including said coil and core and being responsive to the adjusted Positions of such coil and core.

3. A machine according to claim 1 and including a feed screw threaded in a fixed portion of the machine and operatively connected with the drive assembly, the drive assembly including drive means and means for transmitting drive from the drive means to the feed screw, the drive means being operable for moving the entire drive assembly and the work head vertically down into engagement with, and up out of engagement with, the workpiece on the table, and control components operative for moving the drive assembly rapidly vertically when the work head is out of direct proximity to the workpiece, and for moving it downwardly in fine increments when the work head is in engagement with the workpiece.

4. A machine according to claim 3 wherein the rapid movements and the fine increment movements respectively constitute ranges of movments, the drive transmitting means includes a plurality of clutches, one clutch for each range of movement, and additional control means for independently and selectively energizing the clutches for effecting movement of the drive assembly at the respective corresponding rates related to the different clutches.

6. A machine according to claim 3 and including transducers each including a coil and a core movable therein, the transducers including a first set manually adjustable for controlling the movement of the drive assembly, and other transducers mounted in the drive assembly arranged for producing opposing voltage in the two sets, and electrical means responsive to the voltage of the two sets of transducers, operative in response to a null point being achieved between the two sets of transducers for terminating movement of the drive assembly.

7. A machine according to claim 3 and including additional control means which in turn includes manually settable elements mounted on the machine, additional control elements mounted on the drive assembly and movable therewith, the additional control elements being carried bodily by the drive assembly, and means also carried by the drive assembly for actuating and controlling the additional control elements in response to movement of the drive assembly through a predetermined range of movement, whereby to move the additional control elements relative to the main part of the drive assembly for effecting control functions of the work head.

8. A machine according to claim 3 and including, manually settable control elements on the machine, control elements on the drive assembly movable with the drive assembly as the latter is moved toward and from the workpiece on the table, clutch means for controlling the movement of the drive assembly toward and from the workpiece, clutch means for controlling the movement of the control elements carried by the drive assembly, and electrical circuit means for controlling the movement of the drive assembly into and out of proximity to the workpiece and for controlling the control elements thereon when the drive assembly is in proximity to the workpiece by controlling counteracting signals produced by the manually settable control elements on the machine and those carried by the drive assembly.

9. A machine according to claim 8 wherein the control elements include electrical transducers each including a coil and a core movable in and relative to the coil, and the transducers in the control elements mounted on the machine and on the drive assembly respectively produce counteracting voltages, and the machine also including means responsive to the voltages produced, and to a null position between the counteracting voltages, for controlling the movement of the drive assembly and The transducers in the control elements on the drive assembly.

10. A machine according to claim 3 and including means for establishing a plurality of ranges, each range representing an amount of movement of the drive assembly, and means for interrupting the movements of the drive assembly in direction toward the workpiece, and including means for gauging the dimension of the workpiece upon removal of the drive assembly from operating position, and thereafter re-establishing the drive assembly in position relative to the workpiece in accuracy with its position before removal therefrom.

11. A machine according to claim 10 and including stepping switch means providing a plurality of stations, one for each of the ranges, and means for advancing the stepping means pursuant to termination of each step for setting up circuit for the succeeding step.

12. A machine according to claim 1 and including stepping switch means having a rotor, electrical circuit means including the rotor for advancing the rotor, said electrical circuit means including transistor means preventing excessive current to the rotor beyond the capacity of the rotor whereby to prevent damage to the rotor beyond a predetermined period of time.

13. A machine according to claim 1 including manually manipulable means under manual control for moving the drive assembly downwardly into proximity to the workpiece, the machine includes an electrical circuit for so moving the drive assembly downwardly including a pushbutton under manual control, and means responsive to actuation of the pushbutton for advancing the drive assembly and work head, and operative for continuously advancing the assembly and work head pursuant to continuous depression of the pushbutton, and also including means for so advancing the drive assembly and work head to a predetermined extent pursuant to momentary depression of the pushbutton.

17. A machine according to claim 4 wherein the drive transmitting means includes rotatable means, the drive assembly unit includes transducers for controlling an electrical circuit, and the drive transmission means includes rotary elements operative for advancing the transducers in controlling movements according to the progress of the drive through the drive transmitting means.