CA2156993C - U-bolt bending apparatus - Google Patents

Abstract

A vertical frame supports an interchangeable mandrel or die which receives the center portion of an elongated metal rod having opposite threaded end portions, and the rod is clamped to the die by a pivotal locking bar secured by a wedge actuated by a hydraulic cylinder. The frame also includes a vertical plate having upper and lower corner blocks connected by a pair of vertical guide rods. The rods support a horizontal carriage cross bar for vertical movement, and the cross bar pivotally supports upper end portions of a pair of arms each formed by rigidly connected parallel spaced plates having aligned straight cam slots. A pair of bending rollers are supported by the lower end portions of the arms, and a hub member extends between the plates of each arm and supports slide blocks which wave within the cam slots. A hydraulic cylinder moves the cross bar vertically to move the arms and bending rollers along converging paths for overbending the rod around the die.
An elongated adjustment screw is rotatably supported by the lower corner blocks and a center block and extends between the plates forming the arms. The screw has appositely threaded portions engaging the hub members to provide for conveniently and precisely adjusting the spacing between the bending rollers for accommodating dies and rods of different sizes and shapes.

Description

2~5~~9~
U-Y3l~l..i.. BENDING At~fAt?AY..US
Background of t a Invention In the art of machines far cold bending threaded rods into U-bolts, for example, of the general type disclos~ad in U.S. t~atent No. x,936,131 issued to a co-inventor of the present invention, it is common to position an unthreaded center° portion c~ir a metal rod having opposite threaded end portions onto a mandrel or die and to bend the rod around the die b;y moving a pair of b~9nding rollors along parallel linear paths on opposite sides of the clie. the bendirvg rollers are usually supported by arms which form part oi= a movab-ie car°r~iac:le actuated by a hydraul is cylinder. The arms are :adjustable by a cronnecting adjustment screw extending from a hand wheel or crank for adjusting the spacing between the bending rol lens t.o acc:ornmad<it.e d ie~, c;t ~~ i~tFerent sizes and shapes and also f or accommodating rods of different diameters.
hhe bending operation i5 praducc'd t>:y extending and retracting the carriage and the bending rollers so that: the metal rod is bent into a I5 general iy U-shaped conf igur~at.iorr try ior~rn a U-Molt. ~Jhila the bending rollers form the U-bolt witx~ parade! legs. having the threaded end portions, when the carriage and bending r~o-hers are retracted, the metal rod springs back slightly sc~ that, the legs are no longer precisely parallel and diverge outwardly by a slight angle.
U-bolt bending machines have been ~:onsi;ructed wherein the bending rollers are carried by corresponding end portions of pivotally supported arms, and the arms are ba~:ked-up b,y corresponding rollers, the back-up rollers cause the arms and rod bending rollers to move inwardly or converge as the bending rol iers move past the die in order to obtain overbending of the rod around the d'ie. thus when the arms and bending rollers are retracted, the leg portions sprwing back to substantially parapet positions. The bac::kup rc>i ler~~, have also been supported by corresponding adjustable blocks in order to adjust the slightly converging paths of the bending rollers when the carriage moves from its retracted position to its extended position. Such a bending machine, which overbends the U--bolt.~~ t:o obtain substantially parallel legs, has been used for high volume production of ane size U-bolt since substantial down t ime of the bending mac:,h ine a s r~~s:au i r°ed tc~ ad,~ust or reset the backup rol~~er support blocks when a cliff°erent mandrel is used or 2.~ ~6~~3 different diameter rods are to be beni, ini:o U-bolt:s. dne such U-bolt bending machine was consv:rutted <~nd used by Iurner's Alignment and Brake Service, Inc. in Muncie, Indiana and sold under the trademark "Arctic Uend"'.
Summar~_the_ lnyent_ion 1"he present invent i~~r~ is dirwcteai to an improved apparatus or machine for cold bending a metal rod raving opposite threaded end portions into a U-bolt Craving paral let Iec~s vormecl by the end portions.
The apparatus of the inwer~t. ion nc~t on l,y pr°ovicies for averbending the rod so that the threaded legs are parallel after the bending operation, but also provides far convenier~t.9y arcomrrradai, ing pnterc:hanc~eable mandrels or dies of different shapes car aizes ar~cf ais~o threaded rods of different 1 engths and d i ameters . I he U--bo i t taend iog apparai:us or mach ine of the invention may also be positioned hrrrizcyr~tall,y or~ vertically if it is desired to minimize the floor space r~eqdaired by the machine.
In accardance with ~~ne embodiment of the invention., a vertical tubular frame supports an interchangeable mandrel or forming die which receives the center por1:ion of a metal rr~d ha°w~ing t;breaded end portions.
the frame al so inc. l odes a vert icai p E at:e wh ic,i'r has upper and 1 ower earner blocks supporting horiaVonttrl !y spaced ve~~~tic:ai guide rods. A carriage cross bar is supported b.y the guide scads ~vor vertical movement and pivotal ly supports a pair otv depending arms which have lower end portions supporting a corresponding pair of bending rr~1ler<.~. E:ach of the roller support arms is formed by ~r pair of par°allei spaced plates which define corresponding laterally al igned straight sioi:s within the arms.
A hub member extends through t:he s l ~:~t.s w i th in each arm and supports a pair oi= blocks which sl ide on cam surfaces def=fining the slots. A
hydraulis cylinder is supported by t:he top portion of the frame and has a downwardly projectincl p~i<pton rod c:onnfss-ted to the carriage cross bar for moving t;he arms anti bending r~ol Iclr°s vertically aiang sl ightly converging paths extending adjacent the bs~nding die. An adjusting screw is rotatably supported by the lower c:orncer blacks .and a center block and extends between the pare ! 1 a l p l ai:e~> c~f each arm. T he screw has opp0sitely threaded portions rangaging hralas swappori:ing the sl fide blocks, and hand wheel s are mountcxd on oppc~:~ fits c~nd portions of the adjusting screw. Rotat ion of the s~ sew prov ides -!=car conven ient l y ad just ing the spacing between the bending r~a~llers for accommodating threaded rods of different diamel:ers and bending dies oi' ciiivfer°ent size<.> and shapes while also providing for overbending of the rod around tt~e die. ~(he adjustment screw has ad justab I a i:hr°u:~t: co l -I ars ors appos i to side of the center support block to provide tor° pr°ecisel,y po~itior~ing the s>crew axially with respect to the forming die.
Other features arid advantages of t:he inveni:ion will be apparent from the following descr°iption, the accompanying dr°awing and the appended c-laims.
~3rief tlescr°ir7~tion of .t~.~. ~r~awiir~s FIG. 1 is a front elevational viraw of a U-bolt bending machine constructed in accordance witi~ the invenk:.ion FIG. ~ is a side elevational view cJf the bending machine shown in FTG. l;
FIG. 3 is a top view of the machine., taken generally on the line 3-3 of FIG. 1;
FIG. 4 is a fragmentary rear view taken generally on the line 4-4 of FIG. 2;
FIG. 5 is an enlarged fragmentary section taken generally on the ~0 l ine 5-5 of FIG, 1 and showinc; the rod r:ia~np~ng mechanism in a released position;
FIG. 6 is a view s'irnilar to if(a. 5 and showing the clamping mechanism in a positive loc:ked position;
FIG. 7 is a fr°agment.ary sec:t.ion taken gceneral ly on the 1 ine ~1-7 of z5 FIG. L;
FIG. ~ is a view tak~an c;enerally c~ra the I ine 8-~ of FIG. 7 with a retainer plate removed;
FIG. g is a section taken generaBiyy c7n the line 9~-9 of FIG. t; and FIG. 20 is a i~'ragmeratary ~ec;t: ior~ taken generally on the 1 ine 10 ~0 10 of FIG. 9;

~t ~~el~~~ei Description oiy the Pref~.r_red Embodiment FIG. 1 'il Ius~trates a bending apparatus or machine 10 which includes a vertical tubular frame 12 of heavy gauge steel and having a rectangular cross-sectional r:onfiguratir3n (FIG. 3). l~ bar ~l (FIG. 5) projects through slots within the bottom portion of the frame lz and is welded to the front and rear walls of the frame. The forward end portion of the bar 21 receives an inverted ~J--shaped m~rrldrel or forming die 28 which sl ides downwardly into grooves (not shown formed within the sides of the bar Pl. "Ihe die ~g is irrterchangeab-Ir.~ with other dies of different shapes and different widths and may be replaced simply by l iftir~g the die from the bar 21.
hhe upper part of the die ?.8 is adapted to receive and support the center portion of a straight cylindrical metal rod 30 having opposite threaded end portions 32. Pr°eferabi,y, the center of the rod 30 and the T5 top of the die ~8 are provided with c:or°r°espranding marks in accordance with above mentioned Patent tVo. 4,936,.131 in order to provide for conveniently and quickl,~ pc~sitioraing the r°od 30 on the die ~g regardless of the -length of the rod 30. ~s shown ir3 f-tGS. 5 & 6, the center portion of the rod 30 is clamped t;ra the die 28 by a Lever arm 36 which projects through a s~fot 38 within the front wal I c.~l~ thr.x frame lc' and 'is pivotally supported by a crass shaft 41.
fhe outer or ~Forwardly lurojeci.ing end par~tion of the lever arm 36 has an incl fined top cam sur°fac:e 4~ which supports a sl iding wedge block 43 having a part cylindrical recess receiviry a ratatable cross pin 44.
~1 double acting hydra ulic c:y~inder 45 is pivotally supported by a cross bolt 47 secured to the frame 12 and includes a piston rod 48 having an outer end portion threadably connected too the rotatable cross pin 44 within 'the wedge block 4i. ~ senoi--cyl andr~ical bar 49 is rotatably supported within a mating cavity within the top portion of the wedge block 43 and si idably enclage~~ the bat;tcrrn surface of a bearing support block 51 (FIGS. 1 & 5) mounted on the bottorn cr,r7ter portion of a vertical and rectangul ar steel support. pl ate 54 secured ar bo-1 led to the front wall of the frame 1~2.
When the cylinder 45 is actuated t.o ext:end the piston rod 48, the wedge block 43 is 'in thE~ released posit: ion shown in FIG. 5. This permits the lever arm 36 to move l~c~ its ger7erall;y hor'izantal retracted position in response to an upward force produced by a compression spring 57 confined within a tubuiar~ so~.:ket 58 secured to the bar 21. When the cyl finder 4~ is aca:uateci to retract 9.he t; i stc~r~ rod 48, the lever arm is forced downwar~dly tc> compress thc= ~pr~inq 57 and to clamp the center portion of the threaded roci 30 t.o t:he uyga~ar° surface of the forming die ~8, and shown in f :CG. C>.
Referring to I-1G. 1, a set of upper° and rower blocks ~~ are secured or we-Ided to the four cc~r~r~er por°t~ans c~f' t.l~e vertical plate 54, and corresponding blocks 77 are r iyici.ly c:c~nne~ fed i:7y parallel spaced vertical guide rods 70. f he vent ic:al gu fide rods 73 support. a cav~riage 84 for vertical sliding nrovemewt. fine caa~riagcf 84 includes a horizontal cross bar 85 (FrG. 1) which ha=> er~d port.ic~n~ eac:9~ rei:aining a sleeve--type bearing (not shown for rc-~ceiving t:hc~ c.a~rresponding guide rod ~7g. I~
plate 96 is secured or° wedded t. ca t:he c:er~terw caf t:he cross bar 86 and rece i ves an i nv~erted U shaped yoke memlver g8 wh i ch i s secured to the piston rod of a hydraul ical ly ar.tuai:ed girl finder 100. As shown in hIGS.
1 and 2, a U-shaped bracket: 102 is wcelde~i, t:o fi,he top of the cyl incier~
1n0 and pro jects upward) y t a r~ece i ve <~ har i rcanta l bar° 106 and a crass p i n 107. The bar 106 pro jec:t~a through s i ots va i th ~ r~ the front and rear wal l s of the frame 12 and is we R{led to t:he f rams 11r in tf7e same manner as the bar 21 (FIG. 6) at the bottom c~f the t'ramcr.
.rhe .carri age 84 a l sn inc_ i odes a. pa '~r° of arms: 110 which have upper end portions pivcatal-ly corvnerted ire: t.hc~ cra~~s bar 8fi by corresponding pivot shafts 11~ {FtG~. 1 & 7). 1_ach of t:he arms 110 is formed by a pair of parallel spaced plates 174 which havc:a lower er~d portions supporting a cross shaft 116 on which vs mounted a banding roller 118 having a peripherally extending groove 11g. loch t>air of arm plates 114 also have aligned straight or° linearT siot.s 1~3. II~e slots 123 of each arm 110 receive corresponding dear°in~l blocks 1~'_6 {i-1G3. 1 ~ 8) having flat surfaces which slide w=ithirn the slots 1'~:;. l.he bf,aring blocks 1~6 are mounted on redr~ced cyl incd~ical ~lnd pc~r~ ions 1~7 of a spacer hub 130.
Circular retaining plates C31 are sectsrc=c:f 'to the outer ends of the hub 130 by a set of' screws.
An adjustment, screw 1:34 (FIGS. l ~ 0~ has opposite end portions rotatably supported by tf~c~ lc>wer set of t~lo~:ks 77 projecting from the pl ate 54. the adjustment scrc5w 1:34 a i ~o has ax i al 1 y spaced threaded portions 137 and 138 whii:h have r°everse tPrreads arid extend through correspondingly threaded foale> with in the hubs 130. the r..enter portion of the adjustment screw 134 is rotatabl,y ;supported by the center bearing block 51 (FIG. 10) secured to the plate 54 and front wall of the frame 12 by a set of screws 13g. the cer7t:er portion of the adjustment screw 134 is held to the block 51 by a plate t4l retained by a set of screws 142 (FIG. 6). A pair of ad~:iust;rr~en~, t, Par°ust col cars 143 (FIG.
lad are secured to the screw 134 on opposite sides of the support block 51 and are 1 ocked by set screws 144. A pa ~r of ~ rarok~-type hand wheel s 146 are secured to opposite ends o+' the ad~ustmeni; si:rew I34.
As apparent from 1~:C(~. 1, when the adjustment; screw :134 is rotated in one direction or the opposvte direction, the arms 110 pivot inwardly or outwardly on the shafts 11c far° aci;just: Hrrg and precisely selecting the space between 'the forrr~ing or° bending r°ollers 118, his spacing is sel ected accord ing to the ~= izE~ c~f~ thf~ mandrel or d ie ~8 and the diameter of the threaded r°od 30. i~l~e thrust collars 139 are adjusted axially in the screw 134 to pos i t i on l he bend °mg ro p i er°K> 118 prec i se-i y symmetr i cal with respect to the die 28.
In operation of the bending apparatus or machine shown in FIGS. 1-10, after a threaded rod 30 is posii:ionecl on the die 28 and clamped by the locking arm 36 in response to ret.rac:tion of the wedge block 43 with the cylinder 45. the hydrauisc cy~linder° 100 is then actuated to extend its piston rod and move the carriage 84 and arms 110 downward-iy so that the bending rollers 118 bend u;fae rod 30 ~~,ro~arod the die 2.8. As a resent of the cam slots 123 and t:he stationary hubs 130 and bearing blocks 126, the bending rol iers 118 have converg rng arrcl s1 ightly non-1 ~inear paths as the carriage 84 moves downwardly. As a result, the rod 30 is overbent around the die 28 as i-~ iust.ratc~d in FI(:~. :i lo,y i.he converging threaded end portions or legs 148 of a U bolt 150 shown in phantom. When the carriage 84 i s retracted upward i y and the berni i ng r°c~ P 1 ~:~r~s l Ji8 move upwardl y al 0ng diverging paths, the leg portions 148 of a U-bolt 150 spring outwardly to a parallel relat;ianship, thereby praduc:ing a U-bolt with substantially parallel legs.
From the drawing and thf:~ above desr:;ril~t ion, it is apparent that a rod bending apparatus or machine constrr~cte~d in accordance with the present invention, provides desiralrice fElatr~res .and advantages. For example, the apparatus provides the featur~e of 0verbendirrg a threaded rod 30 to obtain a U--bolt 150 with parall~pl lr~~l~, 148 while also providing the feature of conven iently adjust ing the spar; ing l~e~tween the bending rol lens ~e~~
119 simply by rotating the arijus~trnent ~~;.r°ew :134 with one of the hand wheels 146. Thus the bendirq apparatus pravidf:rs far conveniently bending rods of selective different diameters around mandrels or dies 28 of selective different sizes or sf7apes, as c.camrnanly recauired in spring shops where U-belts of different. sizes and sf~alaes a~~e used f~or~ attaching leaf springs to the axles of motor vehicles. the apparatus also operates in a vertical position for carvenient hand) ing of reds and U-bolts and far 1 inviting the floor spacry r°~squ fired by t;f~e apparatus.
>'he construction of the bendincl machine 10 with the tubular steel frame 12 and the suppor°t p l ate 54 mounted on the beam, prov ides for a rigid, economical and ~:iurable conskruct non, and t;he construction and support of the carriage 84 wrcFoperate wii:h the rigid frame 1?_ and the support of the die 28 by the bar 21 to provide for bending a threaded steel rod 30 hav ir~g a sub~,tant ial ci iarnet:er, for examp~Ge, up to 1 1/4 inches in diameter. The ha~draul ical ly a<,:t;uat.ed wedge block 43 between the block 51 and the pivotal lacking arm 36 also assures positive clamping and locking ai I:he threaded rod 30 to the die 28 with substantial force in order t.o permit bending a large diameter rod without the red moving upwardly from the die 28, Another advantage is prcwided by t,h~e s1 iding bearing blocks 126 within the straight cam saot,s :1~3 whi~~.h avoids wearing of the slots when the descending arms 110 are subjected t.a substantial outward forces while the rollers 118 are bending a threaded rod of substantial diameter. In addition, the adjustable cc~ larws 1.39 mormt.ed orr the center portion of the adjustment screw 134 axial ~y an appos itr~ s isles ofi the center support block 51, provide for precisely positioning the adjustment screw 134 axially after the bending machine is assenrbied to assure that the bending rol l ers 118 are prec i se l y s.ymmr=tr i c:a l w i t:l°~ respect to the d ie 28 mounted an the support, bar 2I. The length of the arms 110 is also important for bending -large diameter thrE~aded reds into U-bolts. that is the length between the pivot: pin 11~ tar each <~r~m 110 and the axis of the corresponding bending rall~ar X18 sho~rld 17e greater than a8 inches and preferably within the range of ~2 to 29 inches.
While ~tf~re form of berodirvg apparatus her°ein clescr~ibed Constitutes a preferred embodiment of tile rnvent~orr, it is t.o be underst.aod that the invention is not 1 invited to this precise form of apparatus, and that changes may be made ther~eir, without depart ing i=rom the scope and spirit o~~ the invention as defi'rne~i ire tf7e appervded ~:~aims,.
The inventiar~ having Lhra~> been descrr~ibed, t:he Following is claimed:

Claims (22)

1. Apparatus for bending a straight metal rod having a center portion integrally connecting opposite threaded end portions into a U-bolt having parallel legs formed from the end portions, said apparatus comprising an elongated frame member, a removable forming die supported by said frame member and adapted to receive the center portion of the metal rod, a pair of support arms each supporting a beading roller positioned to engage the rod, a carriage member pivotally supporting said arms, means mounted on said frame member and supporting said carriage member for linear movement between a retracted position and an extended position, means for positively clamping a rod to said die and including a lever pivotally supported by said frame spaced from a support surface, a power actuated wedge member slidably engaging said lever and said support surface, power operated means for moving said carriage member and said arms between said retracted and extended positions, means for moving said arms and said rollers along converging paths in response to movement of said carriage member to said extended position for overbending the rod around said die, an adjustment screw connected to said means for moving said arms, and means for simultaneously adjusting said arms in response to rotation of said screw for conveniently adjusting the spacing between said bending rollers to accommodate rods and dies of different sizes.

2. Apparatus as defined in claim 1 wherein each of said arms has a cam surface, a corresponding bearing member having a substantially flat surface slidably engaging said cam surface, and said adjustment screw is threadably connected with reverse threads to said bearing members for precisely adjusting the spacing between said bending rollers.

3. Apparatus as defined in claim 1 wherein each of said arms comprises a set of parallel spaced plates each having laterally aligned slots defined by substantially flat cam surfaces, a follower member extending between said plates of each said arm and having means forming substantially flat surfaces slidably engaging said cam surfaces of said plates, and said adjusting screw extends between said plates of each said arm and has reverse threaded portions threadably engaging said follower members.

4. Apparatus as defined in claim 1 wherein said frame member comprises a steel tube having parallel spaced front and rear walls, and said means supporting said carriage member comprise a plate secured to said front wall.

5. Apparatus as defined in claim 4 and including parallel spaced cylindrical guide rods supported by said plate and said power operated means comprise a hydraulic cylinder having a piston rod and extending between said frame and said carriage member.

6. Apparatus as defined in claim 1 and including a support block supported by said frame member and supporting a center portion of said screw for rotation, and a pair of thrust collars mounted on said screw on opposite sides of said support block for axial adjustment to provide for precisely positioning said arms and said bending rollers relative to said die.

7. Apparatus as defined in claim 1 wherein each of said arms comprises a set of parallel spaced plates each having laterally aligned substantially straight slots forming cam surfaces, a hub member extending between said plates of each said arm and supporting bearing blocks having substantially flat surfaces slidably engaging said cam surfaces of said plates, and said adjusting screw extends between said plates of each said arm and has threaded portions engaging said hub members.

8. Apparatus as defined in claim 1 wherein each of said arms has a length between the pivot axis for said arm and the axis of the corresponding said bending roller of substantially more than 18 inches.

9. Apparatus as defined in claim 1 and including a support block mounted of said frame and supporting a center portion of said screw for rotation, said support block includes said support surface opposing a cam surface on said lever, said wedge member is positioned between said support surface and said cam scarface, and a hydraulic cylinder connecting said frame to said wedge member.

10. Apparatus as defined in claim 1 wherein said wedge member confines a rotatable cross pin connected to a hydraulic cylinder, and said wedge member supports a rotatable seat member engaging said support surface.

11. Apparatus as defined in claim 1 wherein said frame comprises a metal tube having parallel spaced front and rear walls, and a metal bar extending into aligned slots within said walls and projecting forwardly from said front wall to support said forming die.

12. Apparatus as defined in claim 11 and including a compression spring extending between said lever and said bar to bias said lever to a normally retracted position.

13. Apparatus as defined in claim 1 where in said frame comprises a steel tube having parallel spaced front and rear walls, said means supporting said carriage member for linear movement comprise a plate secured to said front wall, and block members mounted on portions of said plate and supporting parallel spaced guide rods for said carriage.

14. Apparatus for bending a straight metal rod having a center portion integrally connecting opposites threaded end portions into a U-bolt having parallel legs formed from the end portions, said apparatus comprising an elongated frame member, a removable forming die supported by said frame member and adapted to receive the center portion of the metal rod, a pair of support arms each supporting a bending roller positioned to engage the rod, a carriage member pivotally supporting said arms, means mounted on said frame member and supporting said carriage member for linear movement between a retracted position and extended position, means for positively clamping a rod to said die, power operated means for moving said carriage member and said arms between said retracted and extended positions, means for moving said arms and said rollers along converging paths in response to movement of said carriage member to said extended position for overbending the rod around said die, an adjustment screw connected to said means for moving said arms, means for simultaneously adjusting said arms in response to rotation of said screw for conveniently adjusting the spacing between said bending rollers to accommodate rods and dies of different sizes, a support block supported by said frame member and supporting a center portion of said screw for rotation, and a pair of thrust collars mounted on said screw on opposite sides of said support block for axial adjustment to provide for precisely positioning said arms and said bending rollers relative to said die.

15. Apparatus as defined in claim 14 wherein each of said arms has a substantially flat cam surface, a corresponding bearing member having a substantially flat surface slidably engaging said cam surface, and said adjustment screw is threadably connected with reverse threads to both of said bearing members for precisely adjusting the spacing between said bending rollers.

16. Apparatus as defined in claim 14 wherein said frame comprises a steel tube having parallel spaced front and rear walls, said means supporting said carriage member for linear movement comprise a plate secured to said front wall, and block members mounted on portions of said plate and supporting parallel spaced guide rods for said carriage.

17. Apparatus for bending a straight metal rod having a center portion integrally connecting opposite threaded end portions into a U-bolt having parallel legs formed from the end portions, said apparatus comprising a vertical tubular frame including a lower portion and an upper portion, a forming die supported by said lower portion of said frame and adapted to receive the center portion of the rod, a pair of generally vertical support arms each supporting a bending roller positioned to engage the rod, a carriage member pivotally supporting said arms, generally vertical guide means mounted on said frame and supporting said carrier member for generally vertical movement between an upper retracted position and a lower extended position power operated means for moving said carriage member and said arms between said retracted and extended positions, each of said arms having a generally flat cam surface, a bearing member having a generally flat face engaging each of said cam surfaces and providing for moving said arms and acid rollers inwardly towards each other along converging paths when said carriage member moves to said extended position for overbending the rod around said die, and an adjustment screw connecting said bearing members for simultaneously adjusting said arms in response to rotation of said screw for conveniently adjusting the spacing between said bending rollers to accommodate rods and dies of different sizes.

18. Apparatus as defined in claim 17 wherein each of said arms comprises a set of parallel spaced plates each having laterally aligned slots forming said cam surfaces, one of said bearing members extending between said plates of each said arm, and said adjusting screw extends between said plates of each said arm and has threaded portions engaging said bearing members.

19. Apparatus as defined in claim 17 and including means for positively clamping and locking the center portion of the rod to said die member during operation of said operated means and bending of the rod, and said clamping and locking means comprise a power actuated sliding wedge member.

20. Apparatus as defined in claim 14 wherein said frame member comprises a steel tube having parallel spaced front and rear walls, and said means supporting said carriage member comprise a plate to secured to said front wall.

21. Apparatus as defined in claim 14 and including a support block supported by said frame member and supporting a center portion of said screw for rotation, and a pair of thrust collars amounted on said screw on opposite sides of said support block for axial adjustment to provide for precisely positioning said arms and said bending rollers relative to said die.

22. Apparatus as defined in claim 14 wherein each of said arms has a length between the pivot axis for said arm and the axis of the corresponding said bending roller of substantially more than 18 inches.