EP0053803A2

EP0053803A2 - Straightening machine

Info

Publication number: EP0053803A2
Application number: EP81110115A
Authority: EP
Inventors: Burtram I. Newell; Reed Bertolette; Bruce C. Fogarty
Original assignee: BERTOLETTE MACHINES Inc
Current assignee: BERTOLETTE MACHINES Inc
Priority date: 1980-12-08
Filing date: 1981-12-03
Publication date: 1982-06-16
Also published as: EP0053803B1; EP0053803A3; ATE20439T1; DE3174855D1

Abstract

A machine (10) for straightening elongated workpieces (W) comprises at least three sets of coacting tools which include first and second sets (S1, S2) of tools arranged in alternate series along a fixed longitudinal axis (14) for engaging successive longitudinally spaced portions of a workpiece (W) positioned in the machine (10) with its longitudinal center line generally aligned with the longitudinal axis (14). Each set (S1, S2) of tools includes two transversely opposed tools (30) which have transversely spaced work engaging surfaces for engaging opposite sides of the workpiece (W). An operating means (16) is provided for simultaneously reciprocating the tools (30) of the first and second sets (S1, S2) relative to the axis (14) and in opposite direction relative to each other to alternately displace portions of the center line of the workpiece (W) to one and the opposite side of the longitudinal axis with a vibratory motion.

Description

BACKGROUND OF THE INVENTION

This invention relates in general to machines for straightening elongated workpieces and deals more particularly with an improved straightening machine of the type which straightens a workpiece by alternately displacing successive portions of the workpiece in one and opposite directions with a reciprocating motion. More particularly, the invention is concerned with improvements in a straightening machine of the type illustrated and described in U. S. Patent 3,328,995 to Rohlfs, for VIBRATORY STRAIGHTENING MACHINES, assigned by mesne assignments to the assignee of the present invention. A machine of the aforesaid type utilizes a set of reciprocally movable workholders or tools which move in unison and in the same direction relative to a set of stationary tools to impart alternate bending movements to a workpiece to straighten it. Such machines as heretofore available are adapted to straighten relatively small elongated workpieces and have proven most satisfactory for this purpose. However, such machines are not-particularly well adapted for straightening large workpieces such as heavy wrenches or the like. The larger tools and operating mechanism required to reciprocate the movable tools in unison introduce objectionable inertial and vibrational ccnditions. Further, the construction and arrangement of the tooling in a machine of the aforesaid type is such that the machine will accommodate work ieces in only a very limited range of sizes. The clearance between the tools or workholders and an associated workpiece is such that difficulty is often encountered in positioning a severely bent workpiece in the machine for straightening. It is often necessary to prestraighten a severely bent workpiece to enable it to be positioned in the machine for further straightening. The present invention is concerned with the aforedescribed problems.

SUMMARY OF THE INVENTION

In accordance with the present invention a machine for straightening elongated workpieces comprises at least three sets of coacting tools which include first and second sets of tools arranged in alternate series along a fixed longitudinal axis for engaging successive longitudinally spaced portions of a workpiece positioned in the machine with its longitudinal center line generally aligned with the longitudinal axis. Each set of tools includes two transversely opposed tools which have transversely spaced work engaging surfaces for engaging opposite sides of the workpiece. An operating means is provided for simultaneously reciprocating the tools of the first and second sets relative to the axis and in opposite direction relative to each other to alternately displace portions of the center line of the workpiece to one and the opposite side of the longitudinal axis with a vibratory notion. A means is provided for varying the magnitude of reciprocating movement. to vary the amount of workpiece center line displacement between a position of maximum center line displacement and a position wherein the workpiece portions are substantially longitudinally aligned.-

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a fragmentary plan view of a straightening machine embodying the present invention.
Fig. 2 is a fragmentary sectional view taken along the line 2-2 of Fig. 1.
Fig. 3 is a fragmentary sectional view taken along the line 3-3 of Fig. 2.
Fig. 4 is a fragmentary sectional view taken along the line 4-4 of Fig. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Turning now to the drawings, a straightening machine embodying the present invention is indicated generally by the reference numeral 10. The machine 10 is particularly adapted to straighten an elongated workpiece, such as the workpiece W, shown in Figs. 1 and 2, and has a tool assembly designated generally by the numeral 12 which includes at least three sets of coacting tools arranged along a fixed longitudinal axis 14, shown in Fig. 1. The tools are arranged to engage successive longitudinally spaced portions of a workpiece W positioned in the machine with its longitudinal center line generally aligned with the longitudinal axis 14. An operating mechanism indicated generally at 16, and best shown in Fig. 2, simultaneously reciprocates all of the tools in transverse directions relative to the longitudinal axis 14 to alternately displace adjacent portions of the center line of the workpiece W to one and the op. posite side of the axis 14. The operating mechanism 16 furth includes an adjustable drive mechanism, indicated generally a 18, for varying the magnitude of the reciprocal movement of t tools whereby to vary the amount of center line displacement tween a position of maximum center line displacement and a po tion wherein the workpiece portions are substantially longitu inally aligned. The alternate bending of the workpiece porti in one and opposite directions with decreasing motion causes the workpiece to assume a permanently straight set. The mach 10, which constitutes the presently preferred embodiment of t invention, is particularly adapted to straighten a workpiece with no substantial endwise movement of the workpiece occurri during the straightening operation, however, it is not necess ily restricted to such application and may be adapted to perm axial passage of the workpiece during straightening.
Considering now the machine 10 in further detail, i has a base 19 which includes a generally horizontally dispose surface plate 20. The tool assembly 12 is supported on a too frame 22 which comprises a weldment mounted on the surface pl 20. A horizontally disposed bed plate 24 which comprises par of the tool frame is spaced above the surface plate 20 and ha parallel longitudinally extending and upwardly opening T- slot 23, 23 formed therein. The tool frame 22 further includes a of vertically disposed end plates 26, 26 which pass through the bed plate 20 and extend for some distance therebelow, as best shown in Fig. 4.
As previously noted, the machine of the present invention has at least three sets of tools, however, the number of sets of tools used in practicing the invention is optional and may be somewhat dependent upon the length of the elongated workpiece to be straightened, particularly where the straightening operating is to be performed with no substantial endwise movement of the workpiece. The illustrated machine 10 has nine substanti- ; ally identical tool sets, however, for convenience in the further description which follows the tool sets are referred to as first and second tool sets, respectively designated at Sland S2. The first sets Sl, Sl are arranged in alternate series with the second sets S2, S2 along the axis 14, substantially as shown in Fig. 1.
Each set of tools includes two transversely opposed tools 30, 30. A typical tool 30 of a first set Sl, shown in section in Figs. 1 and 2, comprises a rectangular block supported for transverse sliding mcvement in a tool holder 32 which is secured to the tool frame 22 by T-bolts engaged within the T- slots 23, 23. A reaction plate 34 bolted to the tool holder 32, as best shown in Fig. 1, extends laterally into a slot in the tool 30 and provides a reaction surface for a coil spring 36 received in the slot. The coil spring acts between the plate 34 and the tool 30 to bias the tool in a transversely outward direction away from the longitudinal axis 14. The tool 30 has a hardened pad 38 fastened to its inner end which defines an arcuate work engaging surface, as viewed from above in Fig. 1. At its outer end the illustrated tool 30 has an outwardly projec ing upper portion which has another hardened pad 40 fastened to it. The tools 30, 30 which comprise the sets S2, S2 are substan tially identical to the tool of the sets Sl, Sl previously described, but are assembled in their respectively associated tool holders so that the pads 40, 40 are on the lower portions of the tools.
The operating mechanism 16 comprises a cam operated lever system which includes first and second groups of levers respectively generally indicated at Ll and L2. The levers of the first group Ll comprise opposing pairs of levers which include right- hand levers 42, 42 and left-hand levers 42', 42'. The right- hand levers 42, 42 are pivotally supported intermediat their ends on a shaft 43, which is journalled in fixed position on the surface plate 20. An elongated operating bar 44 connects the levers 42, 42 together at their upper ends to move in unison, The left-hand operating levers 42', 42' are supported to pivot on another shaft 45 which is supported for movement relative to the surface plate 20, as hereinafter described. The levers 42', 42' are connected together at their upper ends to move in unison by an elongated operating bar 44'. The opposing inner ends of the , operating bars 44 and 44' are arcuately curved, as viewed in Fi^g: 2 and arranged for engagement with the pads 40, 40 on the tools of the first sets Sl, Sl.
The levers of the second group L2 comprise opposing pairs of right and left-hand levers respectively indicated at 46, 46 and 46', 46'. The right- hand levers 46, 46 are pivotally supported on and arranged along the shaft 43 in alternate series relative to the levers 42, 42, as shown in Fig. 3.An elongated operating bar 48 disposed below the operating bar 44 and inwardly of the levers 42, 42 connects the upper ends of the levers 46, 46 so that the latter levers pivot in unison. The left-hand levers 46', 46' are similarly arranged with respect to the levers 42', 42' along the movable shaft 45 and connected together by an elongated operating bar 48'. The inner ends of the operating bars 48, 48' are arcuately curved, as viewed in Fig. 2, to engage the pads 40, 40 on associated tools 30, 30 which comprise the second sets S2, S2. Follower rollers 50, 50 are journalled on the lower ends of each of the levers of the first and second groups Ll and L2, substantially as shown in Figs. 2 and 3.
The movable shaft 45 is mounted on a plate 54 which is retained by guideways 56, 56, shown in Fig. 1, for limited sliding movement in transverse directions on the surface plate 20. A toggle linkage indicated generally at 58 and connected between the sliding plate 54 and the surface plate 20 is operated by a fluid motor or pneumatic cylinder 60 mounted below the sur-5 face plate 20 and shown in Fig. 2. The toggle linkage 58 is operable to move the lever shaft 45 and its associated left-hand levers 42', 42' and 46', 46' generally toward and away from the tool assembly 12.
The operating mechanism 16 further includes first and second groups of cams Cl and C2 for respectively operating the levers of said first and second groups Ll and L2. The cams Cl and C2 are mounted in alternate series along an elongated cam shaft assembly indicated generally at 62 which includes a tubular outer shaft 64 journalled on brackets 65, 65' mounted on the depending ends of the tool frame side plates 26, 26, as best shown in Fig. 4. The shaft assembly 62 further includes an inner shaft 66 coaxially received within the shaft 64 and supported for axial sliding movement within and relative to the shaft 64, as will be hereinafter discussed. The first and second groups of cams Cl and C2 are mounted on the cam shaft assembly 62 and restrained against axial movement relative to the cam shaft assembly by end collars 68, 68 secured to the tubular shaft 64 for rotation therewith. Each of the cams Cl and C2 has a radially elongated slot 70 which receives..th'e shaft assembly 62 therethrough. A plurality of links 72, 72 connect the inner shaft 66 to the various cams Cl and C2, substantially as shown in Fig. 4. However, it will be noted that the links 72, 72 are connected in alternate series along the shaft to extend from diametrically opposite sides of the shaft 66. A drive pulley-flywheel 74 keyed to the hollow outer shaft 64 is connected to a drive motor 76 which rotates the cam shaft assembly 62. The shaft 66 is shifted axially relative to the shaft 64 by a shifting yoke mechanism indicated generally at 78 connected to one end of the shaft 66 and operated by a fluid ^: motor 80. The fluid motor 80 is preferably of an air over hydraulic type which includes a reciprocally movable piston rod 86 which has a fast stroke in one direction and hydraulic means whereby the return stroke of the piston rod 86 may be adjusted through a substantially infinite range of return speeds. The yoke mechanism 78 is operable to alternately shift the rotating cams of the first and second groups Cl and C2 in opposite radial directions between positions of concentricity and eccentricity relative to the cam shaft assembly 62. Tension springs 82, 82 (one shown in Fig. 2) connected between opposing pairs of levers of the first and second groups Ll and L2 maintain the follower rollers 50, 50 in engagement with respectively associated cams Cl and C2.
At the beginning of the operating cycle the toggle lever 58 is normally in its open or broken line position of Fig. 2. The drive motor 76 is idling and the cams of the first and second groups Cl and C2 are in concentric alignment with the cam shaft assembly 62 so that the levers of the first and second groups Ll and L2 are at rest. Each tool 30 is biased outwardly within its holder 32 and away from the axis 14 by its associated biasing spring 36. Thus, the tools which comprise the tool assembly 12 are in open position and will allow even a severely bent workpiece w to be positioned therebetween.
Upon initiation of the operating cycle the fluid motor 60 first operates to close the toggle linkage 58 whereby to move the lever shaft 45 and the left-hand levers 42', 42' and 46', 46' toward the tool assembly 12 to close the tools 30, 30 or reduce the spacing therebetween: After the tools have been closed the fluid motor 80 operates to shift the inner shaft 66 axially relative to the outer shaft 64 whereby to rapidly move the rotating cams of the first and second groups Cl and C2 ih radially opposite directions to positions of maximum eccentricity relative to the cam shaft assembly 62. An adjustable stop mechanism indicated generally at 82 in Figs. 3 and 4 and associated with the fluid motor 80 may be adjusted to control the length of the stroke of the reciprocally movable piston rod 86 whereby to adjust the shifting movement of the yoke mechanism 78 and the resulting eccentricity of the cams Cl and C2. The cams Cl and C2 cause the respectively associated levers of the first and second Ll and L2 to alternately rock in opposite directions about their respective axes whereby to move the tools of the first and second sets Sl, Sl and S2, S2 in transversely oppcsite directions to produce maximum overbending of alternately adjacent portions of a workpiece W. This overbending causes the workpiece to assume generally serpentine shapes, as viewed from above, and as shown in Fig. 1, as successive portions of the workpiece center line are bent first to one and then to the opposite side of the longitudinal axis 14. The fluid motor 80 preferably operates to cause this initial overbending condition to occur rapidly as the piston rod 86 moves to the limit of its stroke, as determined by adjustment of the stop mechanism 82. The returnstroke of the piston rod 86 is preferably controlled to provide slow return of the cams Cl, C2 from positions of maximum eccentricity to positions of concentricity relative to the shaft assembly 62 In this manner the rocking motion of the levers of the first and second groups Ll and L2 is slowly decreased whereby to gradually "A" decrease the reciprocating motion imparted by the lever system to the tools of the first and second sets Sl and S2. When the cams Cl and C2 return to positions of concentricity with respect to the shaft assembly 62 the workpiece.portions are substantially aligned and take a substantially straight set.
The machine 10 preferably includes mechanism for ascertaining that the cams Cl and C2 move the levers of the first and second groups L1 and L2 to positions corresponding to maximum overbending conditions of the workpiece, as determined by adjustment of the stop mechanism 82, before commencement of the controlled return stroke of the piston rod 86. Suitable timing mechanism such as a timer indicated at 88 in Figs. 3 and 4 may be provided to ascertain that the shaft assembly 62 completes at least one full revolution with the cams Cl and C2 in positions of maximum eccentricity before commencement of the return stroke of the piston rod 86.
Preferably the machine of the present invention also includes shims associated with the tools 30, 30 for varying the spacing between the transversely opposed work engaging surfaces of the tools. A typical shim is indicated by the numeral 90 in Fig. 2. Alternatively, an adjustable arrangement may be provided for anchoring the toggle mechanism 58 to the surface plate 20, as, for example, slots in the plate 20 for receiving the fasteners which secure the toggle mechanism to the plate 20. When the latter arrangement is employed, the spacing between all of the various working engaging surfaces may be simultaneous ly changed by adjusting the position of the toggle mechanism 58 relative to the surface plate 20.

Claims

1. A machine for straightening an elongated workpiece comprising at least three sets of coacting tools including first and second sets of tools arranged in alternate series along a fixed longitudinal axis to engage successive longitudinally spaced portions of a workpiece positioned in said machine with its longitudinal center line generally aligned with said longitudinal axis, each of said sets including two transversely opposed tools having transversely spaced work engaging surfaces engageable with transversely opposite sides of the workpiece, operating means for simultaneously reciprocating said first and second sets of tools in opposite transverse directions relative to said longitudinal axis and each other to alternately displace portions of the center line of the workpiece to one and the opposite side of said longitudinal axis, and means for varying the magnitude of said reciprocating movement to vary the magnitude of center line displacement between a position of maximum center line displacement and a position wherein the workpiece portions are substantially longitudinally aligned. -

2. A machine for straightening an elongated workpiece as set forth in claim 1 including means for biasing said tools of each of said sets in directions away from each other and from said longitudinal axis.

3. A machine for straightening an elongated workpiece as set forth in either claim 1 or claim 2 wherein said tools of each of said sets are movable away from each other from a working position to a workpiece receiving position and said tools are normally maintained in said working position by said operating means.

4. A machine for straightening an elongated workpiece as set forth in claim 3 including means for moving said operating means to allow said tools to move to said workpiece receiving position.

5. A machine for straightening an elongated workpiece as set forth in claim 4 wherein said operating means comprises a lever system and said means for moving said operating means comprises means for moving fulcrums of said lever system.

6. A machine for straightening elongated workpieces as set forth in claim 5 wherein said means for moving said operating means comprises a toggle mechanism. -

7. A machine for straightening an elongated workpiece as set forth in claim 6 wherein said means includes a motor for operating said toggle mechanism.

8. A machine for straightening an elongated workpiece as set forth in claim 1 including means for adjusting the spacing between said workpiece engaging .surfaces of said transversely opposed tools.

9. A machine for straightening an elongated workpiece as set forth in claim 1 wherein said operating means comprises a lever system including first and second groups of levers for respectively moving said first and second sets of tools.

10. A machine for straightening an elongated workpiec as set forth in claim 9 wherein said operating means comprises first and second groups of cams for respectively operating said first and second groups of levers.

11. A machine for straightening elongated workpieces as set forth in claim 10 wherein said cams comprise rotary cyl-, indrical cams and said means for varying the magnitude of reciprocating movement comprises means for moving said cams betwee concentric and eccentric positions relative to anaxis of rotation.

12. A machine for straightening an elongated workpiece as set forth in claim 11 wherein said means for moving said cams is further characterized as means for simultaneously moving said first and second groups of cams in radially opposite directions between said concentric and eccentric positions.

13. A machine for straightening an elongated workpiec as set forth in either claim 11 a claim 12 "A" wherein said means for moving said cams comprises a shaft supporting said cams for rotation and supported for axial shifting movement relative to said cams and link means drivingly connecting said cams to said shaft.

14. A machine for straightening an elongated workpiece as set forth in claim 13 wherein said means for moving said cams includes a motor for axially shifting said shaft.

15. A machine for straightening an elongated workpiece as set forth in claim 14 wherein said means for moving said cams includes means for varying the axial shifting movement of said shaft in response to the operation of said motor.

16. A machine for straightening an elongated workpiece as set forth in claim 1 including means for varying the spacing between said transversely spaced work engaging surfaces.