US3081976A - Wire tensioning device - Google Patents

Description

March 19 1963 c. R. CARLSON ErAL 3,031,976

WIRE TENsIoNING DEVICE Filed June 2, 1961 3 Sheets-Sheet 1 NVEZLTO @J CHT-romyf March 19, 1963 Filed June 2, 1961 C. R. CARLSON ETAL WIRE TENSIONING DEVICE w.. om E 02 i' YD Carl @mj Car/($911., :Donald .Nawkuusoyb Qmam e. mamada@ @cui @.Qof-nnenfk (y1 vromsfw March 19, 1963 C. R. CARLSON Em 3,081,976

v WIRE TENSIONING DEVICE Filed June 2, 1961 3 Sheets-Sheet'l 3 WJ Carl Qgg, Cavlqom :Donald L CNoLwKwLU-om Qllam I Qeddermk C5062 (DQ-Saunen. en.

United States Patent O 3,081,976 WIRE TENSIONING DEVICE Carl Ray Carlson, Donald E. Hawkinson, William E.

Hedderich, and Joel A. Jannenga, Rockford, Ill., as-V The invention relates to a device for applying tension' to a strand of wire or 'thelike and, more particularly, to a wire tensioning device adapted to be used in conjunction with a clamp having a member movable in a predetermined direction to grip one end of the wire and maintain the applied tension after the device is removed.

The general objectrof the present invention is to provide a novel device of the above character which in a single and simple operation applies a predetermined tension to `the wire and subsequently opera-tes the clamp to grip the wire.

Another object is to provide in a tensioning device a novel chuck which facilitates insertion and gripping of the wire preparatory to tensioning, postively grips the wire during tensioning, and automatically releases the wire upon completion of the tensioning operation and after the clamp has been operated to grip the wire.

A further object is to provide a tensioning device which automatically operates the clamp after the desired tension has been applied and while such tension is maintained, thus insuring that the proper tension is held in the wire.

`Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in

which:

FIGURE 1 is a fragmentary elevational view of a tensioning device embodying the novel features of the present invention. FIG.`2 is an enlarged fragmentary sectional view taken along the line 2 2 in FIG. 1. l

FIG. 3 is an enlarged fragmentary sectional view taken along the line 3-3 in FIG. 2 and showing the device during the tensioning operation.

FIG. 4 is an enlarged fragmentary section taken along the line 4-4 in FIG. 2.

FIG. 5 is a perspective view of the jaws of the chuck.

FIG. 6 is an enlarged fragmentary sectional view taken along the line 6-6 in FIG. 2

, FIG. 7 is a diagrammaticview showing the hydrauli Vcircuit of the device.

As shownv in the drawings for purposes of illustration, theinvention is embodied in a device 10 for applying tension to steel rods or wires 11 during the manufacture of Prefabricated concrete beams 12 (FIG. l) in which a plurality of pretensioned reinforcing members are embedded while the beams are being cast. Usuallyrsuch reinforcing members are stretched between spaced supports such as I-beam posts 13 disposed Xon opposite sides of a continuous casting platform (not shown), each wire being held securely at its ends by suitable clamps 14 mounted on the posts.

Herein, each of the clamps comprises a horizontally disposed body 15 bolted at 17 to one of the posts 13 with a clamping mechanism at each end of the body, the clamping mechanism including a wedge element 18 slidable into and out of a slot 19 in the body to cam the adjacent serrated faces of blocks 20 together (see FIG. 7). One clamp of this type is disclosed in our copending application, Serial No. 35,699 led July 13, 1960, to which referen-ce is made for details of disclosure not contained herein. One end of a wire to be tensioned is inserted in one of the clamps, herein the one on the right in FIG. l,

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and the associated wedge 18 is shifted into its slot to lock the blocks 20 against the wire. Then the opposite end of the wire is inserted through the opposite clamp and into the tensioning device 10 which draws the wire through the clamp and thereby applies the desired tension. When the wedge is shifted into its locking position, the Wire will be held securely while the concrete beam 12 is cas-t and hardens.

Preferably, the tensioning dev-ice is mounted on a fiat, lgenerally rectangular `base 21 adapted to be disposed on one side of the clamp and means is provided to support the base against movement toward the clamp as tension is applied to the wire. In this instance, this means comprises a plate 22 secured to the base along one side thereof with a projecting portion 23 extending past the end 26 of the base and over the clamp body. Formed in the underside of this end portion is a downwardly openingy slot` 24 adapted to t snugly over the clamp so that the walls of the slot abut against opposite sides of the clamp and brace the base against end'wise movement relative to the clamp. A finger 25 joined to the base adjacent the other side thereof lies against the top of the body and prevents tipping of the base from side to side.

As shown in FIG. 3, a reciprocating hydraulic actuator 27 is mounted on the base to apply tension of the desired magnitude to the Wire. This actuator preferably comprises a cylinder 28 formed in a housing 29 secured -to the base adjacent the end 30 thereof opposite the clamp with a piston 31 fitted in the cylinder for sliding toward and away from the clamp. The piston rod 32 projects through the wall 33 of the housing and is connected at its outer end to a chuck 34 slidable on the base and adapted -to receive and grip the end of `the wire. In this instance, the end of the rod secured to the chuck is made hollow to accommodate Varying lengths of wire. Thus, when pressure fluid from a suitable source such as a pump 35 (FIG. 7) is admitted through a line 37 to one end of the cylinder, herein the right end as viewed in FIG. 3, the lactuator tensions the wire by drawing it through the clamp, the magnitude of the applied tension depending, of course, upon the pressure developed in the cylinder 28. When the desired tension has been applied, the wedge 18 may be shifted into its locking position to engage the clamp.

In one of its aspects, lthe present invention contemplates a novel chuck 34 which facilitates insertion of the wire 11 into the device and gripping of the wire preparatory to tensioning, positively grips the wire during the tensioning stroke of the piston 31, and automatically releases the wire upon completion of the tensioning operation. To achieve these ends, the chuck is constructed land mounted in a novel manner so that it is clamped tightly against the wire as an incident to the beginning of the tensioning stroke of the piston and is opened automatically during the return stroke.

Herein, the chuck 34 is mounted in a block 38 slidable on the base toward and away from the clamp, the block ibeing formed adjacent one end with a vertical bore 39 into which the end of the rod 32 projects through the side wall 40 of the block. Nuts 41 may be threaded onto the rod and tightened against opposite sides of the wall 40' to secure the block for reciprocating with the rod. Extending through the block from the other side wall of the bore 39 to the side of the block adjacent the clamp is an opening 42 with walls tapering toward the clamp. A plurality of laterally separable jaws 43 (see FIG. 5), the outer sides of which cooperate to form a `correspondingly tapered body 44,` are slidable longitudinallyin this opening and .adapted to lbe disposed around the end of the wire. In this instance, there are three such jaws and -both the outer surfaces of the jaws and the wall of the opening are generally fru-stro-conical in shape, lateral separation of the jaws `being limited by a snap ring 45 seated in an annular groove encircling a cylindrical neck 47 formed on the larger end of the body and concentric therewith. This ring also prevents axial sliding of the jaws relative to each other.

Normally, the block 38 is positioned against a stop formed by the side 48 of a lug 49 secured to the base adjacent the end 26 with the smaller ends of the jaws abutting lagainst the side 48 of the lug around a notch 50 formed in the top of the lug and communicating with the opening `42, as shown in FIG. `6. In this position, the jaws tit loosely in the block and, therefore, are free to separate laterally and receive the free end of the wire which Imay be inserted into the chuck through the notch 50. To guide the wire between the jaws, the inner edges ofthe jaws may be beveled `as at 51 (FIG. 6).

Closure of the chuck to grip the wire preparatory to tensioning thereof is accomplished automatically as `an incident to the beginning of the tensioning stroke of the piston 31 by means of a coiled spring 52' compressed between the larger ends of the jaws and a plug 53 threaded into the adjacent end of the opening `42. Thus, during the initial movement of the block 38 away from the stop, the jaws are spring-pressed through the opening land toward the stop so that the tapering wall 42 coacts with the taper of the jaws to cam the latter together and into gripping engagement with the wire. Continued movement of the block Iaway from the clamp produces Ia frictional drag Ibetween the jaws and the wire which tends to draw the jaws through the opening. Consequently, the jaws are clamped even more tightly against the Wire during tensioning.

Means is provided to open the chuck automatically after the proper tension has been applied and the clamp 14 has been engaged. In this instance, this means comprises a coiled compression spring 54 (FIG. 3) which urges the block back to its normal position against the stop andv coacts with the stop to press the jaws back into their retracted position (FIG. 6). As shown in FIG. 3, the spring 54 is confined within the cylinder 28 between the piston 31 and the inner end of an adjusting screw 55 threaded through the end plate 57 of the cylinder. With this arrangement, the spring 54 is compressed during the stroke of the piston and, upon release of the pressure iiuid, returns the piston to its inactive position thereby opening the jaws so that the wire may be Withdrawn from the chuck.

Pressure tiuid from the pump 35 is delivered to the line 37 communicating with the cylinder 28 through a suitable control valve, in this instance a selectively operable spool-type Valve 58 mounted in a casing 59 on the housing 29. As shown in FIG. 7, the spool 60 is shiftable back and forth between two positions in the casing by means of a hand lever 61 pivotally mounted on the exterior ofthe housing 29. In one of its positions, the spool connects the line 37 with the output of the pump 35 to activate the tensioning actuator 27 and in its other, normal position, the Valve blocks the pump output and connects the line 37 with a line 62 communicating with the pump reservoir.

The invention also contemplates a novel tensioning device which automatically operates the clamp 14 when the desired tension has been applied and while such tension is maintained by the actuator 27, thus automatically completing the operation and insuring that the proper tension is held in the wire. For this purpose, the device includes a second actuator 65 activated in response to a predetermined pressure in the cylinder 28 andoperable to shift the wedge element 14 into its clamping position. Herein, the second actuator 65 comprises a cylinder 67 formed in the housing 29 alongside the cylinder 28 with a plunger 68 reciprocable in the cylinder 67 toward and away from the clamp.

As shown in FIG. 4, the plunger 68 comprises a sleeve 69 telescoping snugly with the cylinder 67 and having a closed end projecting outwardly from the cylinder. Threaded into the outer end of the plunger is a bolt 70 whose head abuts against `one end 71 of a rod 72, the latter being journaled for sliding longitudinally back and forth in a passage 73 forming a guideway through a support 74 fast on the base adjacent the end of the wedge'. The rod 72 projects from opposite sides of the support and a spring 75, coiled around the rod between its head 71 and the side of the support, urges the rod toward the plunger as shown in FIG. 2. An extension spring 77 fastened to the end wall 7S of the cylinder 67 and to the closed end of the plunger urges the latter into its retracted position. When pressure fluid is directed into the cylinder 67, however, the plunger is extended and presses the end 79 of the rod against the wedge to shift the latter into its locking position. When the fluid is released, the two springs 77 and 75 return the plunger and the rod to their retracted positions.

Means responsive to a predetermined pressure in the cylinder 28 is provided to activate the actuator 65 and lock the clamp automatically when the desired tension has been applied to the wire. Herein, this means comprises a pressure-responsive sequence valve 80 (FIG. 7) disposed in a conduit communicating between the cylinders 28 and 67, the conduit being formed by branch line 81 from the line 37 and a, second branch line 82 leading from the line 81 to the cylinder 67. The valve 80 preferably is. `a spring-loaded plunger 83 normally closing branch line 81. When the pressure in the cylinder 28 and the line 37 equals the valve setting, which may be adjusted as desired by means of a screw 84, the valve opens to admit fluid into line 82 thereby to move the plunger 69 and the rod 72 toward the wedge.

It will be apparent that the spring loading of the valve S0 maintains the pressure in the tensioning cylinder 28 as iiuid flows into the cylinder 67, thus holding the proper tension while the clamp is being closed. After the wedge is engaged, the control lever 61 may be returned to its normal position in which the pump output line is closed and the lines 62 and 82 are open to return iiuid exhausted from the cylinders to the reservoir. Thus, the tensioning operation is completed and the device rnay be positioned for insertion of the next wire.

We claim as our invention:

l. In a device for tensioning Wire and the like and subsequently moving a member of a clamp in a predetermined direction to grip the wire and maintain the tension, the combination of, a base adapted to be disposed on one side of the clamp, a plate secured to said base adjacent one end with a projecting end portion adapted to extend over the clamp, said portion being formed with a slot therein adapted to fit snugly over the clamp whereby said' plate supports the base on the clamp, a block slidable on said base toward and away from said one end, a stop mounted on said base adjacent said one end, said block normally abutting against said stop and having an opening therethrough generally paralleling the wire and tapering toward the stop, a plurality of laterally separable jaws disposed within said opening and slidable longitudinally thereof toward and away from said stop, said jaws being adapted to receive a free end of the wire through a slot formed in the stop and communieating with said opening, spring means urging said jaws toward said stop, the outer walls of said jaws being tapered toward said stop, a first reciprocating hydraulic actuator connected to said block and operable when activated to slide the latter away `from the stop whereby said jaws slide in said opening relative to said block, the wall of the opening coacting with the walls of said jaws to cam the latter together and into gripping engagement with the wire thereby to tension the wire, a second reciprocating hydraulic actuator for moving said member in said predetermined direction, a source of iiuid under pressure, a line for delivering said uid to said iirst actuator to activate the latter, a conduit communieating with'both-of said actuators, anda pressure ref-sponsive valve in said conduit normally closing the latter and operable when a predetermined pressure is developed -in said rst actuator to open lthe conduit and admit said -tluid` `to saidv second actuator while maintaining said subsequently moving a member of a clamp in a predetermined direction to grip `the wire and maintain the tension,vthe combination of, a base adapted to be disposed onone side ofthe clamp, means supporting said base against movement towardthe clamp, a stop mounted lori saidfbase, fa Ablock slidable on said base toward and awayfrom the clamp and normally abutting against the side of saidA stop opposite the clamp, said block having an opening therethrough with walls tapering toward said stop, a plurality of laterally separable jaws slidable longitudinally in` said opening and adapted Ito -be disposed around the wire, said jaws being tapered toward and normally abutting against said stop, spring means'urging said jaws toward said stop thereby to close the jaws and grip the wire as said block slides away from the stop, a first reciprocating hydraulic actuator connected to said block and operable when activated to close said jaws and mJve4 the yblock away from theV clamp thereby to grip and tension the wire, a second actuator operable when activated to move the member in said predetermined direction, means for delivering pressure fluid to said rst actuator to activate the latter, and spring means urging said block toward said stop whereby said jaws are pressed against said lstop and the wire is released when said pressure fluid is released from said iirst actuator.

3. In a device for tensioning wire and the like and subsequently moving a member of a clamp in a predetermined `direction to grip the wire and maintain the tension, the combination of, a base adapted to be disposed on one side of the clamp, means supporting said base against movement toward the clamp, a stop mounted on said base, a block slidable on said base toward and away from the clamp and ynormally abutting against the side of said stop opposite the clamp, said block having an opening therethrough with walls tapering toward said stop, a plurality of laterally separably jaws slidable longitudinally in said opening and adapted to be disposed around the wire, the outer walls of said jaws being tapered toward and normally .abutting against said stop, spring means urging said jaws toward said stop thereby to close the jaws and grip the wire as said block slides away from the stop, a rst reciprocating hydraulic actuator connected to said block and operable when activated to close said jaws and move the block away from the clamp thereby to grip and tension the wire, a second actuator operable when activated to move the member in said predetermined direction, means for delivering pressure fluid to said rst actuator thereby to grip and tension the wire, and means responsive to a predetermined pressure in said iirst actuator to activate said second actuator.

4. In a device for tensioning wire and the like and subsequently moving a member of a clamp in a predetermined direction to grip the wire and maintain the tension, the combination of, a base adapted to be disposed on one side of the clamp, means supporting said base against movement toward the clamp, a stop mounted on said base, a block slidable on said base toward and away from the clamp and normally abutting against the side of said stop opposite the clamp, said block having an opening therethrough tapering toward said stop, a plurality of laterally separable jaws slidable longitudinally in said opening toward and away from said stop and adapted to be disposed around the wir'e, the outer walls of said jaws being tapered toward said stop, spring means urging said jaws toward said stop thereby to cam the jaws together and into frictional engagement with the wire as said block slides away from the stop, said stop normally blocking said jaws against sliding in said opening, a iirst reciprocating hydraulic actuator connected to said block and operable when activated to close said jaws and slide the block away from the clamp thereby to grip and tension the wire, a second actuator operable when `activated to move the member in said predetermined direction, means for delivering pressure fluid to said rst actuator thereby to grip and tension the wire, and means responsive to a predetermined pressure in said first actuator to activate said second actuator.

5. In a device for tensioningwire andthe like and -subsequently moving a member of a clamp in a predetermined direction to grip the wire and maintain the tension,` the combination of, a base adapted to be disposed on one side of the clamp, means supporting said base against movement toward the clamp, a chuck mounted on said base for sliding toward and away from the clamp and adapted to receive and grip one end of the wire, a first reciprocating hydraulic actuator connected to said chuck and operable when activated to close said chuck and move the same away from the clamp thereby to grip `and tension the Wire, a second reciprocating hydraulic actuator for moving said member in said predetermined direction, a source of tluid under pressure,

`a line lior delivering said tluid to said iirst actuator thereby to -grip and tension the Wire, a conduit communicating with both of said actuators, and a pressure responsive valve in said conduit normally closing the latter and operable when a predetermined pressure is developed in said first actuator to open the conduit and admit said fluid to said second actuator while maintaining said pressure in the iirst actuator.

6. In a device for tensioning wire and the like and subsequently moving a member of a clamp in a predetermined direction to grip the wire and maintain the tension, the combination of, a base adapted to be disposed on one side of the clamp, means supporting said base against movement toward the clamp, a chuck mounted on said base for sliding toward and away from the clamp and adapted to receive and lgrip one end of the wire, a first reciprocating hydraulic actuator connected to said chuck and operable when activated to close said chuck and move the same away from the clamp thereby to grip and tension the wire, a second actuator operablel when activated to move the member in said predetermined direction, means for delivering pressure fluid to said irst actuator thereby to grip and tension the wire, and means responsive to a predetermined pressure in said rst actuator to activate said second actuator.

7. In a device for tensioning wire and the like, said wire having an end xed relative to the device and a free end, the combination of, a base, means supporting said base adjacent said free end and against movement toward said iixed end, a block slidable on said base toward and away from said Xed end, a stop mounted on said base between said block and said tixed end, said block normally abutting against said stop and having an opening therethrough generally paralleling the wire and tapering toward the stop, a plurality of laterally separable jaws disposed within said opening and slidable longitudinally thereof toward and away from said stop, said jaws being adapted to receive the free end of the wire through the stop, spring means urging said jaws toward said stop as said block slides away from said stop, the outer walls of said jaws being tapered toward the stop v and coacting with the wall of said opening to cam the against the stopwhen said pressure iluid is released` thereby to open said jaws.

8. In a device for tensioning wire and the like, said wire having an end fixed relative to the device and a free end, the combination of, a base, means supporting said base adjacent said free endy and against movement toward said fixed end, a block slidable on said' base towardv and awayl from said xed end, a stop mounted on said base between said block and said fixed end, said block normally abut-ting against said stop and having an opening therethrough generally paralleling the wire and tapering toward the stop, a plurality of laterally separable jaws disposed within. saidV opening and slidable longitudinally thereof toward and away from said stop, said jawsy being adapted to receive the free end of the wire through the stop, spring means urging said jaws toward said stop as said block slides away `from the stop, the outer Walls of said jaws being tapered toward' said stop and coacting with` the wall of said opening to cam the jaws together and intogripping engagement with the wire, and selectively operable means for sliding said block away from said stop therebyv to close said jaws and tension the wire.

9. In a device for tensioning wire andthe like, said wire having one` end fixed relative to the device and a free end, the combination of, a base, means. for supporting the base in a fixed position relative to the wire, a block slidable back and forth on the base along a path paralleling the wire, a stop formed onl said base between said block and said xed end, saidv block normally abutting against said stop and having a frustro-conical opening therethrough generally paralleling the wire and tapering toward the stop, a plurality of laterally separable jaws disposed within said opening and having outer walls forming a generally frustro-conical body slidable longitudinally in said opening to press said jaws together as they' slide toward said stop relative to. said block, said jaws normally abutting at one endy against said stop around a slot therein and being held loosely within said opening to receive the wire through said slot, spring means urging said jaws toward said stop thereby to bring the jaws intogripping engagementy with the wire as the block slides away from the stop, and selectively operable means for sliding said block away from the wire thereby to close said jaws and tension the wire.

References Cited in the le of this patent UNITED STATES PATENTS

Claims (1)

1. 6. IN A DEVICE FOR TENSIONING WIRE AND THE LIKE AND SUBSEQUENTLY MOVING A MEMBER OF A CLAMP IN A PREDETERMINED DIRECTION TO GRIP THE WIRE AND MAINTAIN THE TENSION, THE COMBINATION OF, A BASE ADAPTED TO BE DISPOSED ON ONE SIDE OF THE CLAMP, MEANS SUPPORTING SAID BASE AGAINST MOVEMENT TOWARD THE CLAMP, A CHUCK MOUNTED ON SAID BASE FOR SLIDING TOWARD AND AWAY FROM THE CLAMP AND ADAPTED TO RECEIVE AND GRIP ONE END OF THE WIRE, A FIRST RECIPROCATING HYDRAULIC ACTUATOR CONNECTED TO SAID CHUCK AND OPERABLE WHEN ACTIVATED TO CLOSE SAID CHUCK AND MOVE THE SAME AWAY FROM THE CLAMP THEREBY TO GRIP AND TENSION THE WIRE, A SECOND ACTUATOR OPERABLE WHEN ACTIVATED TO MOVE THE MEMBER IN SAID PREDETERMINED DIRECTION, MEANS FOR DELIVERING PRESSURE FLUID TO SAID FIRST ACTUATOR THEREBY TO GRIP AND TENSION THE WIRE, AND MEANS RESPONSIVE TO A PREDETERMINED PRESSURE IN SAID FIRST ACTUATOR TO ACTIVATE SAID SECOND ACTUATOR.

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