US3253332A - Connecting means and method for reinforcing rods - Google Patents

Description

May 31, 1966 G. H. HOWLETT ET AL 3,253,332

CONNECTING MEANS AND METHOD FOR REINFORCING RODS 2 Sheets-Sheet 1 Filed May 14, 1963 35 INVENTOR.

Georc e H. How/eff- 4 Jams-:5 W Haw/679' 4, i5 Q74 2W H- HOWLETT ET AL CONNECTING MEANS AND METHOD FOR REINFORCING RODS Filed May 1963 FIG. 3

2 Sheets-s 2 INVENTOR. George w/eh mes W How/eff B hi/ W 3,253,332 CONNEQTING MEANS AND METHOD FOR REINFORCING RODS George H. Hewlett, Oakland, and James W. Hewlett, Richmond Annex, Calif., assignors to Howlett Machine Works, a corporation of California Filed May 14, 15 63, Scr. No. 280,357 1 Claim. (Cl. 29-506) The present invention relates to reinforced concrete construction which utilizes lengths of steel rods or bars positioned within the concrete pour, and more particularly to devices and methods for splicing such rods or bars in end to end connection. Where the concrete structure has a length greater than the length of the bars, continuity of the reinforcement is dependent upon splicing of the bars. Heretofore, it has been the practice to weld reinforcing rod ends together.

An object of the present invention is to provide a connecting means and method for reinforcing steel rods which will avoid the necessity of welding and instead provide for the gripping and coupling of adjacent confronting rod ends to be joined in an all mechanical coupler which will afford maximum strength in both tension and compression permitting engineers to design structures using 100% of the physical properties of all of the various grades of reinforcing steel without making allowances for the uncertainty of welding; and which permits the splicing of high strength alloy steels which are difficult to weld and in general to permit the use of all available steels without regard to welding properties.

Another object of the present invention is to provide a connecting means and method for reinforcing steel rods which permits a more rapid and easier installation enabling the contractor to expedite the work by reducing installation time to a fraction of the time required for welded connections and their repair when not satisfactory, and to accomplish this more rapid installation with a minimum of extra equipment and Without expensive handling equipment and without the use of skilled mechanics, thereby permitting form work to proceed more rapidly and thus further cooperate with the utilization of full properties of the steel in effecting an overall reduction in cost of construction.

A further object of the present invention is to provide a connecting means and method of the character described and which will produce a positive connection of reinforcing steel bars in a manner which permits ready inspection enabling the project inspector a positive means of examining a joint for acceptability without resorting to X-rays or other similar means of examination, and which connection when made in accordance with the present invention is permanent and not affected by heavy or continuous vibration.

The invention possesses other objects and features of advantage, some of which of the foregoing will be set forth in the following description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of this specification. It is to be understood, however, that variations in the showing made by the said drawings and description may be adopted within the scope of the invention as set forth in the claims.

Referring to said drawings (two sheets):

FIGURE 1 is a perspective view of a concrete structure and reinforcing rods prepared and assembled with the coupling device and method of the present invention, portions of the view being exploded for better illustration of the device and method.

FIGURE 2 is a side elevation of a pair of joined reinforcing rods and coupling device of the present invention, with the latter broken away and shown partly in crosssection.

United States Patent 3,253,332 Patented May 31, 1966 'ice FIGURE 3 is an enlarged side elevation partly in section of a part of the coupling device showing assembly.

FIGURE 4 is a longitudinal cross-sectional view of the apparatus used for setting the wedge sleeves in an intermediate step of the method of the present invention.

The connecting means of the present invention is particularly adapted for splicing reinforcing steel rods or bars 11, 12, 13, 14, 15, 16 and 17 as illustrated in FIGURES 1 and 2 of the drawings, and consists briefly of a pair of longitudinally split sleeves 21 and 22 formed with a pair of external spiral cam lands 23 and 24 of reverse pitch and with serrated interior surfaces 26 and 27 dimensioned for gripping the peripheries of each pair of rods to be joined, such as rods 16 and 17 in FIGURE 2; a tubular housing 28 formed with a pair of internal spiral cam lands 31 and 32 of reverse pitch extending inwardly from the opposite ends 33 and 34 of the housing 28 and formed to receive in mating threaded fit the cam lands 23 and 24 on sleeves 21 and 22; and means 36 for rotating housing 28 relative to sleeves 21 and 22 to compress the sleeves into tight gripping engagement with rods 16 and 17 and to displace the rods axially toward each other in end to end compression approaching the yield point of the rods. Preferably, the sleeves are positioned adjacent the confronting aligned ends 37 and 38 of the reinforcing rods 16 and 17 to be joined so that rotation of the housing 28, as above noted, will cause, by reason of the reverse pitch of the pairs of mating cam lands 23, 24 and 31, 32 an axial displacement of the rods into abutment of confronting rod ends 37 and 38. The serrations on the interior surfaces 26 and 27 of the two sleeves may be formed by cutting a spiral thread into these surfaces to define fine annular sharp teeth which are adapted for embedding in the periphery of the rods. In this connection, it may be observed that the sleeves 21 and 22 as well as the housing 28 are formed of high strength hardened steel so as to permit their use with all commercial grades of reinforcing steel and the application of requisite forces, as described herein. i

As will be observed in FIGURE 2, the cam lands 23, 24 and 31, 32 are fashioned as spiral threads but with one side of the thread (forming the cam land itself) formed long and relatively fiat and at a small angle of incline with respect to the longitudinal axis of the coupling; and with the other side of the thread formed as an offset shoulder having a larger angle, nearly perpendicular, to the axis. For purposes of identification, the shoulders formed in the housing at the edge of the spiral convolutions forming cam lands 31 and 32 have been given reference numerals 41 and 42; and the shoulders formed as spiral convolutions at the longitudinal ends of cam lands 23 and 24 of the two sleeves have been given reference numerals 43 and 44. The fashioning of the relatively flat elongated cam lands arranged essentially end to end, as viewed in longitudinal section in FIGURE 2, affords a structure wherein essentially the entire length of the sleeves, and correspondingly the engaged length of the housing, acts with wedging action on the engaged rods 16 and 17 when the housing is rotated, clockwise as viewed in FIGURES l and 2, relative to the sleeves and rods. As will be observed from FIGURE 2, cam lands 24 on the upper sleeve 22 and rod 17 diverge outwardly relative to the longitudinal axis of the device in the direction of rod end 37. At the same time, the spiral pitch of the engaged cam lands 24 and 32 will cause the sleeve to move inwardly toward the center of the housing upon relative clockwise rotation of the housing. The other set of cam lands 23 and 31 on the sleeve and housing at the lower end of the assembly, as seen in FIGURE 2, also diverge in an axial direction toward the center of the housing and the pitch of these engaged lands is such as to cause relative movement of the lower sleeve 21 toward the center of the housing upon the rods.

is satisfactory for this purpose.

upon relative clockwise rotation of the housing, as above noted. Accordingly, two important effects occur upon the above described rotation of housing28. One, the wedge action of the engaged cam lands force the sleeves tightly against rods 16 and 17 and the greater the rotational force applied to the sleeve, the greater the compressive action of the sleeves on the rods. The forming of the sleeves with longitudinal slotted portions 46 and 47 permits the ready circumferential tightening of the sleeves The second important action is the axial displacement of the rods towards each other so as to place the confronting rod ends 37 and 38 into compression abutment. It is a feature of the present invention that sulficient torque is applied to the housing to apply endwise compression loads on the rods to a point approaching the yield point of the rods themselves. The two joined rods thus become in effect one solid rod with a strength in tension and compression equivalent to the full maximum strength of the individual rods. While the rods are placed in end to end compression as above explained, the housing is placed in corresponding tension and must have a cross-sectional area and strength capable of carrying the load with an adequate factor of safety. Preferably, as above noted, the housing is formed of high strength steel having a tensile strength in excess of 150 thousand pounds per square inch, and the housing is designed with a crosssectional area somewhat greater than the rods which the housing joins. The internal sleeves are preferably of hardened steel so as to take a proper bite into the rods, and we prefer sleeves having a hardness of approximately 60 on the Rockwell C scale (file hardness).

Any suitable means may be used for torquing up the assembly. A torque wrench, as illustrated in FIGURE 1, It consists of a long handle 51 for obtaining leverage and which is formed at one end with a fixed jaw 52 having a segmental cylindrical face adapted to engage a portion of the periphery of the housing 28. A second circular jaw 53 is pivotally secured as by bolt 54 to swing into a complementary circumferential engagement of housing 28 opposite jaw 52, the shape and mounting of jaw 53 serving to grip the housing tightly upon the application of a clockwise rotary movement to handle 51, as seen in FIGURE 1 and as suggested by arrow 56. A longitudinally extending indicator bar 57 is anchored at one end to handle 51 adjacent the jaw section, as by screws 58, and extends longitudinally in overlying relation to the handle into juxtaposition of its outer end a full circumferential grip of the rods.

tools. For many installations the bevelling of the rod ends is not required.

As will be appreciated, conventional reinforcing rods or bars are formed with a series of longitudinally spaced annular ribs or shoulders 66 and with one or more longltudinally extending ribs 67 for better gripping of the concrete. These ribs are removed at the rod area 68 gripped by the sleeves, see FIGURE 3, so as to afford the sleeves The reinforcing bars to be joined may either be cold-pressed round to remove the deformations 66 and 67 or the rod end portions may be turned with a suitable tool such as a bolt threader, or the like. Ideally, the ribs 67 and 68 should be just removed but the taking of some additional material, perhaps 0.010 inch to 0.030 inch, may be desirable to obtain a cylindrical surface and correct for minor irregularities in the bars.

The next step in the assembly, as depicted in FIG- URE 3, is to slide on the sleeves 21 and 22 moving them over the confronting ends of the reinforcing bars to be joined and onto the cleared portion 68. As above noted, right and left hand threaded sleeves are selected for the two bar ends. Preferably, and in accordance with a desired intermediate step of the present method, the sleeves are set onto the bar portions 68 by press fitting the sleeves thereon prior to the mounting of the outer housing 28. An apparatus for setting the sleeves is illustrated in FIG- URE 4 and consists of a tubular body 71 having an interior spiral cam land 72 formed in the same manner as the cam lands in housing 28 so as to receive in mating threaded fit the cam land 23 of sleeve 21. Accordingly, after sleeve 21 has been slid onto the end portion 68 of rod 16, the sleeve and rod assembly may be threaded into one end 73 of the body 71, as illustrated in FIGURE 4.

with a lateral torque scale 59. Rotary displacement of the handle may be effected by any convenient power means or by block and tackle, or the like. Provision is made for this purpose for cable attachment to the handle, see clevises 61 and 62 fastened to the handle 51 adjacent its outer end 63.

Preferably, the periphery of housing 28 is knurled or otherwise provided with a series of longitudinally extending teeth 64 which will interfit with similarly formed teeth on the interior faces of jaws 52 and 53 so as to provide an improved and adequate gripping of the wrench on the housing. Other conventional types of wrench surfaces such as polygonal flats and the like may be used. The wrench 51 should be designed to withstand and to apply torque to the housing in the order of up to about 10,000 foot pounds.

As a feature of the present invention the confronting rod ends 37 and 38 may be bevelled, as seen in FIGURES l and 2, so that when the rods are positioned in face to face fit, as seen in FIGURE 2, they will be fitted together in rotationally interlocked relation. Thus, one rod may not rotate relative to the other rod. This construction cooperates with the reverse pitch of the spiral cam lands to provide a positive'locking up of the assembly and holding fast of the parts against heavy and continuous vibration. Preparation (bevelling) of the rod ends where this feature is to be used may be done in a fabricating shop or in the field by the use of appropriate portable cutting As will be observed in FIGURE 4, the mated cam lands 23 and 72 diverge in an interior axial direction so that force applied to the internal end 37 of the rod will cause the mated cam lands to wedge the sleeve tightly into compression around the rod end portion 68. The opposite end portion of body 71 is formed with a smooth axially aligned cylinder 74 which is adapted to receive for axial reciprocation a cylindrical plunger 76 which may be inserted into cylinder 74 from one end 77 of the body. The interior end 78 of plunger 76 is formed as an anvil for abutment against rod end 37 for applying axial force to the rod. The assembly, as illustrated in FIGURE 4, is then placed in a power operated press such as a hydraulic press and force applied axially between end 73 of the body and the opposite end 79 of plunger 76, as indicated by force arrows 81 on end 73 and force arrow 82 on plunger end 79. Preferably, the force applied to set the wedge sleeve is up to approximately the yield point of the material of the reinforcing bar 16 and accordingly, the hydraulic press should be capable of applying pressure upwards of 75,000 pounds per square inch. The application of such a force within the apparatus, as illustrated in FIGURE 4, fully embeds the interior sleeve teeth 26 into the rod periphery and evens out all minor inaccuracies in tolerances in the rod and sleeve so that all of the cam land surfaces are brought into parallel concentric relation.

After the sleeves 21 and 22 have been set upon the confronting rod ends to be joined, as illustrated in FIG- URE 4, the rod ends are inserted into the opposite ends of the housing 28 and the latter rotated in order to draw the rod ends internally into the interior of the housing and into abutment, as illustrated in FIGURE 2. Torque wrench 51 may then be applied, as illustrated in FIG- URE 1, and block and tackle or other means applied to torque up the assembly, as hereinabove described. The use of a torque wrench as illustrated is convenient in enabling the project inspector to visually observe the amount of torque applied to the coupling to make sure that a positive and foolproof joint is provided. The inspector may also observe the yielding of the one rod which is normally anchored in concrete such as rods 11, 12, 14 and 16 in FIGURE 1. Experience will indicate the approximate yield point of the rods.-

The coupler of the present invention may be readily dimensioned for use with all of the conventional reinforcing bar sizes extending from 188 having a diameter of 2.257 inches down to size 5 having a diameter of 0.625 inch; and may be used with all of the usual grades of reinforcing steel such as A.S.T.M. A-15 and A-408, billet steel, intermediate and hard grade, A.S.T.M. A-431, billet steel, 60,000 p.s.i. yield point, A.S.T.M. A-432, high strength billet steel, A.S.T.M. A-16, rail steelregular and special, A.S.T.M. A-160, axle steel, structural, intermediate and hard grade.

The coupling will withstand bending of reinforcing steel to 30; and the coupling is suitable for all deformations under A.S.T.M. specification A-305.

We claim:

The method of splicing structural rods which comprises mounting on a pair of rods to be joined a pair of tubular longitudinally split sleeves formed with a pair of external circumferentially extending spiral cam lands of reverse pitch and with generally cylindrical interior surfaces dimensioned for fitting the peripheries of said rods and with internally projecting teeth adapted for embedding into said rods, compressing said sleeves upon said rods adjacent ends thereof to be joined by holding each of said sleeves in a surrounding mating cam land and applying an axial load to the interior mounted rod substantially equal to its yield point thereby obtaining a corresponding pre-set embedding of said teeth in said rods, thereafter engaging said sleeves in a tubular housing formed with a pair of interior spiral cam lands of reverse pitch formed to receive in mating threaded fit said first mentioned cam lands, and rotating said housing relative to said sleeves to displace said sleeves into compressive gripping engagement with said rods and to displace said rods into end to end compression.

References Cited by the Examiner UNITED STATES PATENTS 960,377 6/1910 McLean 285-328 1,435,028 11/1922 Stewart 285-417 1,646,660 10/1927 Prince 287--114X 1,712,108 5/1929 Goeller 287-114 1,833,008 11/1931 Thorpe 287119 1,901,286 3/1933 Coe 287-60 2,051,499 8/1936 Siegle 285-417 2,382,003 8/1945 Cones 287 60 2,453,079 11/1948 Rossmann -128 X 2,930,642 3/1960 Howlett 287-114 FOREIGN PATENTS 659,899 2/ 1929 France.

OTHER REFERENCES Stressrods, Rods, Inc., page 8 relied upon.

CARL W. TOMLIN, Primary Examiner.

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