US3869900A

US3869900A - Apparatus for bending wire into a sinuous shape

Info

Publication number: US3869900A
Application number: US448475A
Authority: US
Inventors: Harry H Norman
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-03-06
Filing date: 1974-03-06
Publication date: 1975-03-11
Anticipated expiration: 1992-03-11

Abstract

Wire is bent sinuously, for example to form a zig-zag shaped spring, by an apparatus having identical oscillator/overbend assemblies situated above and below the plane in which the wire is formed. Each such assembly includes a bending pin carried by a holder that is rotationally mounted on a shuttle. Drive means, including respective oscillator and translator cams, imparts rotation to the pin holder and translation to the shuttle. An overbend arm and a backup tool, driven by an overbend cam drive mechanism, overbend the wire about the bending pin of the same assembly. During a portion of each bending cycle, the bending pin of one assembly is rotated to and caused to dwell at a bending position at which the pin holder is generally perpendicular to the longitudinal axis of the zig-zag. The bending pin of the other assembly is rotated so as to contact and bend incoming wire around the now stationary bending pin of the one assembly. Concurrently the overbend arm and backup tool of the one assembly are driven into contact with sections of the wire on opposite sides of the dwelling pin so as to overbend the wire. As the overbend arm and backup tool are withdrawn, combined rotation of the bending pin holder and translation of the shuttle causes the bending pin to move laterally from the dwell position out of the newly formed convolute. The convolute at the other side of the zig-zag then is formed as the bending pin of the other assembly dwells in its bending position.

Description

Unite States atet 1191 Norman 1 1 APPARATUS FOR BENDING WIRE INTO A SINUOUS SHAPE [75] Inventor: Harry II. Norman, Los Angeles,

Calif. [73] A i Stephen Baliski,Gardena,Calif.;a

part interest [22] Filed: Mar. 6, I974 21 Appl. No.: 448,475

[52] U.S. CI 72/384, 72/306, 72/403, 140/105 [51] Int. Cl. B21d 41/02 [58] Field of Search 72/383, 384, 385, 403,

72/394, 392, 304, 305, 306, 307, DIG. 16;

[56] References Cited UNITED STATES PATENTS 2,097,193 10/1937 Jacobs 72/383 2,305,266 12/1942 Lincoln et a1... 72/DIG. 16 2,645,252 7/1953 Norman 72/D1G. 16 2,998,045 8/1961 Horton 72/D1G. 16 3,180,371 4/1965 Hughes.... 140/90 3,382,896 5/1968 Hopkcs 140/105 Primary E.raminerC. W. Lanham Assistant Examiner-James R. Duzan Attorney, Agent, or Firm-Allan M. Shapiro [57] ABSTRACT Wire is bent sinuously, for example to form a zig-zag 1 Mar. 11, 1975 parts rotation to the pin holder and translation to the shuttle. An overbend arm and a backup tool. driven by an overbend cam drive mechanism, overbend the wire about the bending pin of the same assembly.

During a portion of each bending cycle, the bending pin of one assembly is rotated to and caused to dwell at a bending position at which the pin holder is generally perpendicular to the longitudinal axis of the zig-zag. The bending pin of the other assembly is rotated so as to contact and bend incoming wire around the nowstationary bending pin of the one assembly. Concurrently the overbend arm and backup tool of the one assembly are driven into contact with sections of the wire on opposite sides of the dwelling pin so as to overbend the wire. As the overbend arm and backup tool are withdrawn, combined rotation of the bending pin holder and translation of the shuttle causes the bending pin to move laterally from the dwell position out of the newly formed convolute. The convolute at the other side of the zig-zag then is formed as the bending pin of the other assembly dwells in its bending position.

14 Claims, 21 Drawing Figures PATENTED 1 1975 3.869.900

SHEET UHF 12 PATENTED 1 I975 SHEET UZUF 12 PATENTED 1 3,869,900

SHEET DSUF 12 PATENTED 1 1975 3,869,900

SHEET OBUF 12 PATENTED 1 3.889 900 SHEET 08 UP 12 ELTENTEU 1 5975 3.869800 SHEEI 09 0F 12 APPARATUS FOR BENDING WIRE INTO A SINUOUS SHAPE I BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to apparatus for bending wire continuously into a sinuous shape.

2. Description of the Prior Art The formation of straight wire into a sinuous shape, e.g., to make a zig-zag spring, has several difficulties. The use of a stationary bending mandrel does not permit continuous spring formation. Therefore, provision must be made to remove the bending pin from the path of the spring travel after formation of each convolute. This is particularly complicated if the convolute is of narrow-U or hairpin shape. Removal of the pin then necessitates either withdrawal of the pin from the the plane of wire travel, or translation of the pin within the hairpin convolute, substantially lateral to the zig-zag longitudinal axis.

If spring wire is used, simple bending of the wire into the convolute shape is not sufficient. When the bending force is withdrawn, the cast of the wire will cause the bend to open somewhat, resulting in a convolute size greater than desired. Overbending is necessary to compensate for this resilience. It is particularly desirable to have the Overbending force applied near the closed end ofthe convolute being formed. This necessitates the insertion of a bending head and a backup tool on opposite sides of the bending pin, respectively to overbend the wire and to prevent the formed convolute from rotating about the bending pin as the-Overbending is accomplished. The overbend assembly itself must be withdrawn from the wire path to permit continuous spring formation.

The principal object of the present invention is to provide an apparatus for continuously bending wire into a sinuous shape, and having provision for removing the bending pin after formation of"each convolute and for Overbending the wire in the immediate region of the bending pin.

An earlier spring-forming machine is shown in the inventors US. Pat. No. 2,645,252. That apparatus utilizes a pair of bending pins mounted at diagonally opposed positions on a single oscillating platform. As the platform rotates in one direction, both pins engage the wire to form it into a Z-shape. During counter-rotation of the platform the pins again engage the prebent wire. Continued rotation in this direction forces one of the pins to overbend the wire around the other platformmounted pin, and against a retaining pin that is inserted into the bending plane for this portion of the bending cycle.

In the springforming machine just described, the Overbending force is applied by a bending pin situated at the extreme opposite end of one leg of the hairpinshaped convolute being formed. Backup is provided by a retaining pin situated at the midpoint of the other leg of the convolute. In contradistinction, an object of the present invention is to provide a spring-forming machine in which the overbend force is applied by a separate assembly including cooperative tool elements which engage the wire on opposite sides of, but adjacent to, the bending pin.

SUMMARY OF THE INVENTION These and other objectives are achieved by providing a wire forming apparatus having upper and lower oscillator/overbend assemblies situated respectively above and below the plane in which the sinuous shape is formed. Each assembly includes a bending pin extending normally through the spring-forming plane and supported by a holder. The holder itself is rotationally mounted on a shuttle which translates back and forth during the spring forming operation.

Appropriate drive means, including oscillator and translator cams, imparts rotation to the pin holder and translation to the shuttle during portions of the wire bending cycle. These cams are configured so that for a portion of each cycle, the bending pin dwells in a position in which the holder is disposed generally perpendicular to the longitudinal axis of the zigzag. While dwelling in this position, incoming wire is bent around the pin by the bending pin of the other assembly, the holder of which is being driven rotationally. At the same time, the wire is overbent around the dwelling pin by an overbend assembly.

The overbend assembly itself comprises an overbend arm having a head at one end that engages the wire on the incoming side of the bending pin. Linked to the overbend arm is a backup tool which is interposed on the other side of the bending pin. An overbend drive mechanism causes the overbend arm and backup tool to overbend the wire while the bending pin of the same oscillator/overbend assembly is in its dwell position. Thereafter, the overbend assembly is withdrawn laterally out ofthe path ofwire travel. The overbend assembly is controlled by an overbend cam that is driven in unison with the oscillator and translator cams. Subsequent to convolute formation, back and forth movement of the shuttle and concurrent rotation of the pin holder causes the previously stationary bending pin to move laterally out of the hairpin-shaped convolute just formed. Meanwhile the bending pin of the other oscillator/overbend assembly is brought to its dwell position for formation of the next convolute.

BRIEF DESCRIPTION OF THE DRAWINGS A detailed description of the invention will be made with reference to the accompanying drawings wherein like numerals designate corresponding elements in the several figures. These drawings, unless described as diagrammatic or unless otherwise indicated, are to scale.

FIG. 1 is a front view of the inventive apparatus for forming wire into a sinuous spring.

FIG. 2 is a sectional view ofthe spring forming apparatus as seen along the line 2-2 of'FIG. l. The relative position of the translator, overbend and oscillator cams and their associated followers is evident herein.

FIG. 3 is a transverse sectional view of the spring forming apparatus along the line 3-3 of FIG. 2, showing the lower shuttle and associated translator mechanism.

FIG. 4 is a transverse sectional view along the line 4-4 of FIG. 2, showing the overbend and oscillator cam configurations.

FIG. 5 is a sectional view along the line 5-5 of FIG. 4, showing the overbend drive mechanism.

FIG. 6 is a transverse sectional view along the line 6-6 of FIG. 2, showing the overbend assemblies.

FIG. 7 is a transverse sectional view along the line 7-7 of FIG. 2, showing the oscillator drive coupling.

FIG. 8 is a sectional view along the line 88 of FIG. 3, showing the chute which receives the spring being formed. 1

FIGS. 9 through l8 diagrammatically illustrate the wire bending operation of the present invention, at successive stages of the spring forming cycle.

FIG. 19 is a fragmentary transverse sectional view similar to that of FIG. 6. The apparatus is shown at the same stage of the bending cycle as in FIG. 9.

FIGS. 20A and 20B are graphs showing the interrelationship of the motions imparted by the translator, overbend and oscillator cams shown in FIGS. 2, 3 and 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT The following detailed description is of the best presently contemplated mode of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention since the scope of the invention best is defined by the appended claims.

The inventive apparatus continuously forms an incoming wire 26 (FIGS. 6 and 19) into a flat sinuous spring 27. As it is formed, the spring 27 moves rearwardly through a horizontal chute 28 the frontal opening of which is evident in FIG. 1. The spring 27 and the chute 28 lie along a horizontal median plan 29 which divides the apparatus 25 into symmetric upper and lower oscillator/overbend assemblies 30U and 30L. These assemblies cooperate to form the spring 27.

A rigid frame 31 supports all of the components of the apparatus 25. The frame 31 consists of like upper and lower sections joined along the median line 29, as by bolts 32. A drive shaft 33 for the upper assembly 30U extends upwardly from the housing 31 through a bearing 34. Continuous counterclockwise rotation is imparted to the drive shaft 33 via a belt 35 and a pulley 36. Similarly, continuous clockwise rotation is imparted to the lower assembly 30L via a belt 37, a pulley 38 and a drive shaft 39 extending through a bearing 40 mounted to the frame 31. The

belts

35 and 37 are driven synchronously by a common motor 41 and differential transmission 42 shown symbolically in FIG. 1.

The upper and lower oscillator/overbend assemblies 30U and 30L are identical, thus a description of one is applicable to the other.

For simplicity, like numerals are assigned to corresponding parts of the two assemblies. Where necessary to distinguish between upper and lower components, the designating numeral is followed by the corresponding letter U (upper) of L (lower).

Actual bending of the incoming wire 26 is accomplished in part by a pair of

rigid bending pins

45L and 45U which extend vertically through the median plane 29. As evident in FIGS. 1, 2 and 3, the pin 45L is affixed to the end of an arm or holder 46L that is pivotally supported by a shuttle 47L. During portions of the bending cycle, the holder 46L is rotated alternately clockwise and counterclockwise about an axis 48L. This is accomplished by means of an oscillator drive assembly 49L.

The oscillator drive assembly 49L includes an oscillator cam 50L (FIGS. 2 and 4) formed as a groove in a dual cam 51L that is keyed to the drive shaft 39. An oscillator cam follower 52 at one end of a lever 53 rides within the cam 50L groove. The oscillator cam 50L is configured so that during each rotation of the drive shaft 39, the lever 53 will pivot once back and forth about the axis of the lever support shaft 54. The shaft 54 is mounted in a bearing 55 affixed to the frame 31.

At the other end of the lever 53 is an arcuate rack gear 57. This engages a pinion 58 having a vertical shaft 59 supported by bearings 60,61 in the frame 31. Preferably the ratio of the

gears

57,58 is selected so that the arcuate movement imparted to the gear 57 by the oscillator cam follower 52 will cause the shaft 59 to rotate through a full 360 in one direction, and a full 360 in the opposite direction during a single rotation of the dual cam 51. Rotational motion of the shaft 59 is coupled to the pin holder 46L by means of a flexible link coupling 64L attached at its lower end to the shaft 59. The device 64L advantageously is a Schmidt coupling such as that sold commercially by the Tool Steel Gear and Pinion Company of Cincinnati, Ohio. The coupling 64L comprises a set of pivotally interconnected links 65 which transmit rotational motion despite displacement or lateral offset of the shafts interconnected by the coupling.

As shown in FIG. 2, one end of the coupling 64L is attached to the shaft 59. The other end is attached to ajournal 66 extending through a bearing 67 in the shuttle 47L. The pin holder 46L is clamped to the journal 66 as by screws 68. With this arrangement, rotational motion of the shaft 59 is imparted to the holder 46L even during translation (i.e., back and forth motion) of the shuttle 47L.

A similar oscillator drive assembly 49U including 21 Schmidt coupling 64U is provided to rotate the upper pin holder 46U about an axis 48U. As evident in FIG. 1, the upper shuttle 47U which carries the pin holder 46U is offset to the left of the vertical center line 69 of the apparatus 25. The lower shuttle 47L is symmetrically offset to the right of the center line 69. Thus, the axes 48U, 48L of revolution of the upper and lower bending pins 45U, 45L are symmetrically disposed on opposite sides of the center line 69, and hence are equally spaced from the longitudinal center line 69' (FIG. 19) of the chute 28.

As shown in FIGS. 2 and 3, the shuttle 47L is adapted to move back and forth with respect to the front of the apparatus 25. To facilitate such translation, the shuttle 47L is attached to the front end of a pair of spaced parallel support rods 70L. The rods 70L are mounted to the frame 31 by front and

rear sleeve bearings

71, 72. A yoke 73 interconnects the rods 70L interiorly of the frame 31. The yoke 73L carries at its center a cam follower 74L which engages the groove 75L of a translator cam 76L that is keyed to the drive shaft 39.

With this arrangement, rotation of the drive shaft 39 and the translator cam 76L imparts translational motion to the shuttle 47L via the cam follower 74L, the yoke 73L and the support rods 70L. The translator cam groove 75L is configured so that the axis 48L of revolution of the bending pin 45L is moved back and forth in synchronism with revolution of that pin during portions of the bending cycle. This is described more fully below in conjunction with FIGS. 9 18 which depict the bending cycle, and with the graph of FIG. 208 which defines a preferred configuration for the translator cam 76L.

As evident in FIG. 2, the upper shuttle-47U similarly is driven back and forth by an upper translator cam 76U keyed to the upper drive shaft 33. As seen in FIGS.

2 and 8, the axes of the upper support rods 70U lie in a plane parallel to but spaced above the chute 28. An

upper cam follower 74U, supported by a yoke 73U between the support rods 70U, extends upwardly into the groove 75U of the translator cam 76U. FIG. 8 also shows the horizontal offset of the support rods 70U and 70L and the corresponding offset of the oscillator axes 48U and 48L.

During the spring forming operation, a pair of overbend assemblies 80U, 80L cooperate with the bending pins 45U, 45L to overbend the wire 26, so that when the bending force is released, the wire will assume the desired convolute shape. Details of the overbend assemblies are shown in FIGS. 1 and 4 6.

The lower overbend assembly 80L includes an overbend lever 8IL (FIGS. 5 and 6) fastened to a shaft 82L by a nut 83L. The thickness of the overbend lever 81L is considerably greater than that of the wire 26 being formed. The vertical position of the lever 81L is such that the'horizontal center line of that lever coincides with the median plane 29 of the apparatus 25. With this arrangement, a tool steel head 84L affixed to the end of the lever 81L will come into bending contact with the wire 26 (FIG. 19) when the shaft 82L is rotated counterclockwise as viewed in FIG. 6. The projecting portion 85L of the tool head 84L but comes in contact with the wire 26 is rounded to prevent scoring of the wire during the overbend operation.

The overbend assembly 80L also includes a backup tool 86L which is inserted behind the convolute being formed (FIG. 19). The backup tool 86L is generally wedge-shaped, but has a rounded leading edge 87L to prevent damage to the wire 26. The backup tool 86L is attached to a carriage 88L one end of which is pivotally mounted to the chute 28 by a shaft 89L. The other end of the carriage 88L is connected to the overbend lever 81L by a link 90L. As seen in FIG. 5, one end of the link 90L is pivotally connected to the bifurcated rear end of the lever 81L by means of a pivot pin 91L. The other end of the link 90L is connected to the bifurcated end of the carriage 88L by a pivot pin 92L.

With this arrangement, as the overbend lever 81L rotates to bring the tool 84L into contact with the wire 26, the backup tool 86L simultaneously is interposed on the other side of the bend being formed (FIG. 19). As the lever 81L rotates in the opposite direction to withdraw the head 84L, the backup tool 86L concurrently is withdrawn. Such motion of the overbend assembly 80L is imparted by an overbend cam 95L (FIGS. 2, 4 and 5) formed as a groove in the upper surface of the dual cam 51L.

An overbend cam follower 96 (FIGS. 4 and 5) rides within the groove 95L. The cam follower 96 is attached to the end ofan overbend drive arm 97 that is pivotally mounted to the frame 31 by means of a shaft 98 jour' naled to upper and

lower bearings

99 and 100. A spacer 101 maintains the arm 97 in a horizontal plane above the dual cam 51.

At the other end ofthe arm 97 is an arcuate rack gear 102 that engages a pinion gear 103 affixed to the lower end of the shaft 82L. As the drive arm 97 pivots back and forth about the shaft 98, the

gears

102, 103 convert this motion to rotation of the shaft 82L, and hence to operative engagement and disengagement of the overbend assembly 80L. The overbend cam 95L is config' ured to impart such motion to the assembly 80L to accomplish overbeing of the wire 26 at the appropriate portion of the wire bending cycle. The shaft 82L is .journaled within a pair of bearings 104 which are mounted in a boss 105L extending upwardly from a ledge 106 at the front of the apparatus 25. The upper overbend assembly U is identical to the lower assembly 80L.

DESCRIPTION OF THE SPRING FORMING OPERATION The spring forming operation carried out by the apparatus 25 is illustrated by FIGS. 9 l8, and by the graphs of FIGS. 20A and 208. These graphs show the motion imparted by the upper and lower oscillator, translator and overbend cams during a complete bending cycle, which takes place during one revolution of the upper and lower

cam drive shafts

33 and 39. The graphs specify radial cam displacement (along the ordinate) as a function of angle (along theabscissa). Thus the graphs of FIG. 20B define a preferred embodiment for the lower oscillator, translator and overbend cams 50L, 74L and L. The corresponding upper oscillator, translator and overbend cams are defined by the graphs of FIG. 20A, which are identical to those of FIG. 20B, but offset by 180. Indicated along the abscissa of FIGS. 20A and 20B are the points in the operating cycle illustrated respectively by FIGS. 9 through 18. FIG. 19 shows the apparatus 25 at the end of the operating cycle; this configuration corresponds to the start (FIG. 9) of the next cycle.

At the beginning of the cycle (FIG. 9) the bottom overbend assembly 80L has overbent the wire 26 about the lower bending pin 45L to form a convolute 110 of the spring 27. At this time, the pin 45L is at a position of maximum lateral offset in one direction from the longitudinal center line 69' of the spring 27. The lower shuttle 47L is at its rearmost position with respect to the front of the apparatus 25. Thus the axis 48L of the holder 46L is shown at its leftmost position in FIG. 9. The upper bending pin 45U is situated approximately diagonally opposite the pin 45L on the other side of the center line 69.

In FIG. 10 the lower overbend assembly 80L is retracting. The overbend tool 84L has disengaged from the wire 26 and the backup tool 86L is being withdrawn. The resilience of the wire 26 causes it to spring back from the overbent condition imparted (FIG. 9) by the assembly 80L, so that the convolute I10 assumes the desired Ushape.

It is now necessary to withdraw the pin 45L from the newly formed convolute 110. To accomplish this, the pin must move approximately linearly in a direction perpendicular to the center line 69. Such linear motion is accomplished by a combined clockwise rotation of the holder 26L, imparted by the oscillator cam 50L, and back and forth translation of the shuttle 47L imparted by the lower translator cam 76L.

Eventually the pin 45L clears the other end 111 of the newly formed convolute 110. Clockwise rotation of the holder 46L continues, eventually bringing the pin 45L into bending contact (FIG. 13) with the incoming wire 26. Meanwhile, the upper pin 45U and holder 46U also are rotating clockwise (FIGS. 10 and I1) until-the pin 45U again is at its extreme lateral displacement (FIG. 12) from the center line 69. The pin 45U then dwells in this position while the incoming wire 26 is bent around the pin 45U (FIGS. 13 and 14) by the cooperation of the bending pin 45L and the upper overbend assembly 80U.

To accomplish the bending, the pin 45L engages the incoming wire 26 (FIG. 13) and starts to pull this wire around the now stationary pin 45U. Simultaneously, the upper overbend assembly 80U starts to close. The backup tool 86U is interposed into the previously formed convolute 110, in contact with the segment on the incoming wire just beyond the pin 45U. The overbend tool or head 84U at the end of the lever 81U contacts the incoming'wire 26. Thus the wire 26 is simultaneously bent by the pin 45L and the overbend head 84U to form the new convolute 111. The backup tool 86U prevents rotation of the convolute 111 about the pin 45U, and permits the head 84U to overbend the wire 26 as shown in FIG. 14.

Note that the step of FIG. 14 is identical to that of FIG. 9, except that the bending is performed by the upper overbend assembly 80U about the upper pin 45U. As indicated by FIGS. 20A and 208, FIG. 14 occurs at the 180 point, after one-half revolution of the

cam drive shafts

33 and 39. The steps shown in FIGS. 14 through 18 thus correspond to those shown in FIGS. 9 through 13, except for an interchange of upper and lower components. Thus in FIG. 15 the pin 45U translates linearly in a direction perpendicular to the axis 69' to clear the newly formed convolute 111. Counterclockwise rotation of the upper and lower holders 46U, 46L continues (FIG. 16) until the lower pin 45L reaches its extreme lateral displacement (FIG. 17) and the pin 45U engages the incoming wire 26 to begin formation of the new convolute 112. The pin 45L dwells at this position, as the pin 45U and the overbend assembly 80L cooperate (FIG. 18) to bend the wire 26 around the now stationary pin 45L. The backup tool 86L is interposed as overbending is accomplished by the head 84L (FIG. 19). The bending cycle now repeats, beginning with the step shown in FIG. 9. In this manner, the wire 26 continuously is formed into the flat sinuous spring 27.

Intending to claim all novel, useful and unobvious features shown or described:

I claim:

1. Apparatus for bending wire into a zig-zag shape, comprising:

first and second identical oscillator/overbend assemblies situated facing each other on opposite sides of the plane of said zig-zag, each oscillator/overbend assembly comprising;

an oscillator assembly including a bending pin extending normally through the plane of said zig-zag, and a holder supporting said bending pin, said holder being mounted for rotation about an oscillator axis parallel to but offset from said pin,

an overbend assembly including an overbend arm and a backup tool mounted to move between a withdrawn position spaced from the wire being bent and an engaged position in which said arm and backup tool cooperate to overbend said wire about the bending pin,

oscillator cam drive means operative during each bending cycle for rotating said pin and holder about said oscillator axis first in one direction and then in the opposite direction. and thereafter for causing said pin to dwell for the completion of the bending cycle in a dwell position in which a line between said pin the oscillator axis is approximately perpendicular to the longitudinal axis of the zigzag,

overbend cam drive means operative during each bending cycle for driving the overbend assembly into the engaged position when said pin is in said dwell position to overbend said wire about the dwelling pin, and thereafter to withdraw said overbend assembly, and

wherein said oscillator/overbend assemblies are synchronized so that while the bending pin of one assembly is in the dwell position the bending pin of the other assembly is being rotated, whereby alternate convolutes of said zig-zag are formed alternately by said first and second oscillator/overbend assemblies.

2. Wire bending apparatus according to claim 1 wherein each oscillator/overbend assembly further includes;

a shuttle mounted for linear movement parallel to the longitudinal axis of said 'zig-zag, said bending pin holder being rotationally mounted on said shuttle, and

translator cam drive means, operative during each bending cycle, for moving said shuttle and the pin holder carried thereby back and forth as said pin holder is rotated, the combined rotation and translation thereby imparted to said pin holder causing the bending pin supported by that holder to move generally perpendicular to the longitudinal axis of said zig-zag out of the convolute just formed, to rotate into contact with incoming wire so as to bend this wire around the dwelling pin of the other oscillator/overbend assembly in unison with engagement of the overbend assembly associated with that dwelling pin, and then to rotate back in the opposite direction to the dwell position in preparation for formation of the next convolute.

3. Wire bending apparatus according to claim 2 wherein each oscillator, overbend and translator drive means of each oscillator/overbend assembly is controlled by a respective oscillator, overbend and translator cam, together with motor means for driving all said cams in unison.

4. Wire bending apparatus according to claim 3 wherein the oscillator, overbend and translator cams of one oscillator/overbend assembly are identical to the corresponding cams of the other oscillator/overbend assembly, but are displaced with respect thereto.

5. Wire bending apparatus according to claim 3 wherein said overbend assembly comprises;

an overbend drive shaft mounted at a fixed location laterally offset from the dwell position of the bending pin of the same oscillator/overbend assembly, said overbend arm being mounted on said shaft for pivotal motion rotation therewith,

a pivotally mounted backup tool carriage linked to said overbend arm for movement therewith, said backup tool being generally wedge-shaped and attached to said carriage, pivotal motion of said overbend drive shaft thereby causing overbend arm to pivot into engagement with the wire being formed and causing said carriage to insert the wedge portion of said backup tool into the recess between the convolute being formed and the adjacent previously formed convolute,

and wherein said overbend drive means imparts limited rotational motion to said drive shaft first in one direction as the bending pin in the same oscillatorloverbend assembly is in the dwell position, and

then in the other direction.

6. Wire bending apparatus according to claim wherein said overbend drive means comprises a pinion gear attached to said drive shaft and a lever having at one end a cam follower that engages said overbend cam and having at the other end an arcuate rack gear that engages said pinion gear, said overbend cam being configured to pivot said lever alternately in opposite directions to impart said limited rotational motion.

7. Wire bending apparatus according to claim 3 wherein said shuttle is affixed to the end of a support member mounted to permit reciprocal motion thereof parallel to the longitudinal axis of said Zig-zag but offset therefrom both horizontally and vertically, said support member having a cam follower attached thereto which engages said translator cam, said translator cam being configured to impart controlled reciprocation of said support member during said bending cycle.

8. Wire bending apparatus according to claim 7 wherein said bending pin holder is attached to ajournal situated in a bearing carried by said shuttle, and wherein said oscillator drive means comprises;

an oscillator drive shaft having a pinion gear affixed thereto,

an oscillator lever arm having at one end a cam follower that engages said oscillator cam and having at the other end an areuate rack gear cooperating with said pinion gear, said oscillator cam being configured to pivot said oscillator lever arm alten nately in opposite directions to impart rotation to said oscillator drive shaft first in one direction then in the other, followed by a dwell period during which no rotation is imparted, and

a flexible coupling connected to transmit the rotation of said oscillator drive shaft to said journal independent of the translation of said shuttle.

9. Apparatus for forming wire into a flat sinuous spring, a pair of convolutes of said spring being formed during each bending cycle, said apparatus comprising:

identical upper and lower oscillator/overbend assemblies disposed above and below the spring-forming plane in which said spring is formed, each assembly comprising:

a. a rigid bending pin extending normally through said spring-forming plane,

b. an oscillator mechanism for revolving said bending pin about an oscillator axis parallel to but offset from said bending pin, said mechanism being operative during each bending cycle to revolve said bending pin alternately in one direction and then in the reverse direction about said oscillator axis, and to cause said pin to dwell at a convoluteforming position for the remainder of said bending cycle,

e. a shuttle for translating said pin and at least a part of said oscillator mechanism back and forth in a plane parallel to said spring-forming plane, so that said oscillator axis likewise translates back and forth with said shuttle,

d. a cooperating overbend arm and a backup tool mounted to be driven between a withdrawn position out of contact with said wire and an overbending position in which said arm and tool engage sections of the wire being formed on opposite sides of the bending pin when in the convolute-forming position, and e. cam-controlled drive means for driving the overbend arm and backup tool of one assembly into 5 the overbending position to overbend the wire about the bending pin of the same assembly while that pin dwells in the convolute-forming position, and for concurrently driving the oscillator mechanism of the other assembly so that the revolving bending pin of the other assembly engages and bends the wire about said dwelling bending pin in unison with overbending by said arm and backup tool.

10. Apparatus according to claim 9 wherein said oscillator mechanism includes,

a pin holder pivotally mounted to said shuttle for rotation in a plane parallel to but spaced from the spring-forming plane, said holder supporting said bending pin in spaced parallel relationship with said pivotal mounting so that the pivotal mounting axis corresponds to said oscillator axis and is offset laterally from the longitudinal centerline of said flat spring, and

wherein said cam-controlled drive means imparts rotational motion to said pin holder alternately in opposite rotational directions.

11. Apparatus according to claim 10 wherein said shuttle is carried by a reciprocable support, and wherein said cam-controlled drive means includes;

a translator cam situated in a plane parallel to said spring-forming plane, motor means for continuously rotating said translator cam, and a translator cam follower attached to said reciprocable support and engaging said translator cam, so that rotation of said translator cam imparts back and forth motion to said shuttle.

12. Apparatus according to claim 11 wherein said cam-controlled drive means further comprises;

an oscillator cam situated in a plane parallel to said spring-forming plane and also rotated by said motor means,

a pivotally mounted arm having at one end an oscillator cam follower engaging said oscillator cam and having at the other end a gear,

cooperative gear means for converting pivotal motion of said arm, imparted via said oscillator cam follower as said oscillator cam is rotated, into rotational motion, and

coupling means for communicating the rotational motion of said gear means to said shuttle-mounted pin holder,

said oscillator cam being configured to pivot said arm alternately in opposite directions during a single rotation of said oscillator cam whereby revolving motion in opposite directions alternately is imparted to said pin during a portion of said single oscillator cam rotation.

13. Apparatus according to claim 12 wherein said cam-controlled drive means further comprises;

an overbend cam disposed in a plane parallel to said spring-forming plane and also rotated by said motor means,

an overbend drive shift to which said overbend arm is attached, and

an overbend cam follower assembly including an overbend cam follower and a cooperative linkage for converting motion imparted by said overbend cam during rotation thereof into rotational motion of said overbend drive shaft, said overbend cam being configured to impart said rotational motion alternately in opposite directions during selected portions of a single rotation of said overbend cam. 14. Apparatus according to claim 9 wherein said cam-controlled drive means includes cams configured: l. to cause simultaneous revolution of one bending pin and back and forth translation of the associated shuttle so that said one bending pin moves generally laterally out from the convolute just formed, 2. to cause revolution of the other bending pin to its convolute-forming position of maximum lateral displacement from the spring longitudinal centerline, 3. to cause continued rotation of said one bending pin in the same direction so that said one bending pin engages incoming wire and bends said incoming wire around the other bending pin as it dwells in said convolute-forming position, 4. to cause the overbend arm and backup tool associated with said other bending pin to engage and overbend said incoming wire in unison with bending by said one bending pin. and thereafter to revolve said one bending pin in the opposite direction into its convolute-forming position of maximum lateral displacement from the spring longitudinal center-line, said one bending pin then dwelling in said convolute-forming position while wire is bent around it by the other bending pin and by the overbend arm and backup tool associated with said one bending pin.

Ell

Claims

1. to cause simultaneous revolution of one bending pin and back and forth translation of the associated shuttle so that said one bending pin moves generally laterally out from the convolute just formed,

1. Apparatus for bending wire into a zig-zag shape, comprising: first and second identical oscillator/overbend assemblies situated facing each other on opposite sides of the plane of said zig-zag, each oscillator/overbend assembly comprising; an oscillator assembly including a bending pin extending normally through the plane of said zig-zag, and a holder supporting said bending pin, said holder being mounted for rotation about an oscillator axis parallel to but offset from said pin, an overbend assembly including an overbend arm and a backup tool mounted to move between a withdrawn position spaced from the wire being bent and an engaged position in which said arm and backup tool cooperate to overbend said wire about the bending pin, oscillator cam drive means operative during each bending cycle for rotating said pin and holder about said oscillator axis first in one direction and then in the opposite direction, and thereafter for causing said pin to dwell for the completion of the bending cycle in a dwell position in which a line between said pin the oscillator axis is approximately perpendicular to the longitudinal axis of the zig-zag, overbend cam drive means operative during each bending cycle for driving the overbend assembly into the engaged position when said pin is in said dwell position to overbend said wire about the dwelling pin, and thereafter to withdraw said overbend assembly, and wherein said oscillator/overbend assemblies are synchronized so that while the bending pin of one assembly is in the dwell position the bending pin of the other assembly is being rotated, whereby alternate convolutes of said zig-zag are formed alternately by said first and second oscillator/overbend assemblies.

2. Wire bending apparatus according to claim 1 wherein each oscillator/overbend assembly further includes; a shuttle mounted for linear movement parallel to the longitudinal axis of said zig-zag, said bending pin holder being rotationally mounted on said shuttle, and translator cam drive means, operative during each bending cycle, for moving said shuttle and the pin holder carried thereby back and forth as said pin holder is rotated, the combined rotation and translation thereby imparted to said pin holder causing the bending pin supported by that holder to move generally perpendicular to the longitudinal axis of said zig-zag out of the convolute just formed, to rotate into contact with incoming wire so as to bend this wire around the dwelling pin of the other oscillator/overbend assembly in unison with engagement of the overbend assembly associated with that dwelling pin, and then to rotate back in the opposite direction to the dwell position in preparation for formation of the next convolute.

2. to cause revolution of the other bending pin to its convolute-forming position of maximum lateral displacement from the spring longitudinal centerline,

3. to cause continued rotation of said one bending pin in the same direction so thaT said one bending pin engages incoming wire and bends said incoming wire around the other bending pin as it dwells in said convolute-forming position,

4. Wire bending apparatus according to claim 3 wherein the oscillator, overbend and translator cams of one oscillator/overbend assembly are identical to the corresponding Cams of the other oscillator/overbend assembly, but are displaced 180* with respect thereto.

4. to cause the overbend arm and backup tool associated with said other bending pin to engage and overbend said incoming wire in unison with bending by said one bending pin,

5. and thereafter to revolve said one bending pin in the opposite direction into its convolute-forming position of maximum lateral displacement from the spring longitudinal center-line, said one bending pin then dwelling in said convolute-forming position while wire is bent around it by the other bending pin and by the overbend arm and backup tool associated with said one bending pin.

5. Wire bending apparatus according to claim 3 wherein said overbend assembly comprises; an overbend drive shaft mounted at a fixed location laterally offset from the dwell position of the bending pin of the same oscillator/overbend assembly, said overbend arm being mounted on said shaft for pivotal motion rotation therewith, a pivotally mounted backup tool carriage linked to said overbend arm for movement therewith, said backup tool being generally wedge-shaped and attached to said carriage, pivotal motion of said overbend drive shaft thereby causing overbend arm to pivot into engagement with the wire being formed and causing said carriage to insert the wedge portion of said backup tool into the recess between the convolute being formed and the adjacent previously formed convolute, and wherein said overbend drive means imparts limited rotational motion to said drive shaft first in one direction as the bending pin in the same oscillator/overbend assembly is in the dwell position, and then in the other direction.

6. Wire bending apparatus according to claim 5 wherein said overbend drive means comprises a pinion gear attached to said drive shaft and a lever having at one end a cam follower that engages said overbend cam and having at the other end an arcuate rack gear that engages said pinion gear, said overbend cam being configured to pivot said lever alternately in opposite directions to impart said limited rotational motion.

8. Wire bending apparatus according to claim 7 wherein said bending pin holder is attached to a journal situated in a bearing carried by said shuttle, and wherein said oscillator drive means comprises; an oscillator drive shaft having a pinion gear affixed thereto, an oscillator lever arm having at one end a cam follower that engages said oscillator cam and having at the other end an arcuate rack gear cooperating with said pinion gear, said oscillator cam being configured to pivot said oscillator lever arm alternately in opposite directions to impart rotation to said oscillator drive shaft first in one direction then in the other, followed by a dwell period during which no rotation is imparted, and a flexible coupling connected to transmit the rotation of said oscillator drive shaft to said journal independent of the translation of said shuttle.

9. Apparatus for forming wire into a flat sinuous spring, a pair of convolutes of said spring being formed during each bending cycle, said apparatus comprising: identical upper and lower oscillator/overbend assemblies disposed above and below the spring-forming plane in which said spring is formed, each assembly comprising: a. a rigid bending pin extending normally through said spring-forming plane, b. an oscillator mechanism for revolving said bending pin about an oscillator axis parallel to but offset from said bending pin, said mechanism being operative during each bending cycle to revolve said bending pin alternately in one direction and then in the reverse direction about said oscillator axis, and to cause said pin to dwell at a convolute-forming position for the remainder of said bending cycle, c. a shuttle for translating said pin and at least a part of said oscillator mechanism back and forth in a plane parallel to said spring-forming plane, so that said oscillator axis likewise translates back and forth with said shuttle, d. a cooperating overbend arm and a backup toOl mounted to be driven between a withdrawn position out of contact with said wire and an overbending position in which said arm and tool engage sections of the wire being formed on opposite sides of the bending pin when in the convolute-forming position, and e. cam-controlled drive means for driving the overbend arm and backup tool of one assembly into the overbending position to overbend the wire about the bending pin of the same assembly while that pin dwells in the convolute-forming position, and for concurrently driving the oscillator mechanism of the other assembly so that the revolving bending pin of the other assembly engages and bends the wire about said dwelling bending pin in unison with overbending by said arm and backup tool.

10. Apparatus according to claim 9 wherein said oscillator mechanism includes, a pin holder pivotally mounted to said shuttle for rotation in a plane parallel to but spaced from the spring-forming plane, said holder supporting said bending pin in spaced parallel relationship with said pivotal mounting so that the pivotal mounting axis corresponds to said oscillator axis and is offset laterally from the longitudinal centerline of said flat spring, and wherein said cam-controlled drive means imparts rotational motion to said pin holder alternately in opposite rotational directions.

11. Apparatus according to claim 10 wherein said shuttle is carried by a reciprocable support, and wherein said cam-controlled drive means includes; a translator cam situated in a plane parallel to said spring-forming plane, motor means for continuously rotating said translator cam, and a translator cam follower attached to said reciprocable support and engaging said translator cam, so that rotation of said translator cam imparts back and forth motion to said shuttle.

12. Apparatus according to claim 11 wherein said cam-controlled drive means further comprises; an oscillator cam situated in a plane parallel to said spring-forming plane and also rotated by said motor means, a pivotally mounted arm having at one end an oscillator cam follower engaging said oscillator cam and having at the other end a gear, cooperative gear means for converting pivotal motion of said arm, imparted via said oscillator cam follower as said oscillator cam is rotated, into rotational motion, and coupling means for communicating the rotational motion of said gear means to said shuttle-mounted pin holder, said oscillator cam being configured to pivot said arm alternately in opposite directions during a single rotation of said oscillator cam whereby revolving motion in opposite directions alternately is imparted to said pin during a portion of said single oscillator cam rotation.

13. Apparatus according to claim 12 wherein said cam-controlled drive means further comprises; an overbend cam disposed in a plane parallel to said spring-forming plane and also rotated by said motor means, an overbend drive shift to which said overbend arm is attached, and an overbend cam follower assembly including an overbend cam follower and a cooperative linkage for converting motion imparted by said overbend cam during rotation thereof into rotational motion of said overbend drive shaft, said overbend cam being configured to impart said rotational motion alternately in opposite directions during selected portions of a single rotation of said overbend cam.