US3827464A

US3827464A - Manufacture of springs

Info

Publication number: US3827464A
Application number: US00323891A
Authority: US
Inventors: T Clarke; R Quarmby; G Matts
Original assignee: British United Shoe Machinery Ltd
Current assignee: Noxet UK Ltd
Priority date: 1972-01-21
Filing date: 1973-01-15
Publication date: 1974-08-06
Anticipated expiration: 1991-08-06
Also published as: FR2168585A1; GB1417698A; DE2301491A1; FR2168585B3

Abstract

The invention relates to machines for use in forming attaching loops in generally longitudinal orientation at or from end portions of coil springs. An end portion of a spring is located axially of a machine axis and transversely of a machine axis by locating means of the machine. The machine also comprises orientating means for facilitating orientation of the spring about the machine axis so that the end of the wire of which the spring is formed is correctly positioned. The machine further comprises looping means for operating on the located and orientated end portion of the spring to form a loop of a desired configuration and orientation.

Description

ilnite tates tent 1191.

1arlre et a1. Aug. a, 11974 [54] MANUFACTURE @F SPRINGS 3,069,024 12/1322 Penny 140/103 3,338,272 81 7 B r t 140115 5 Inventors? Term James Leonard Clarke; 3,737,960 611973 131 1151; 312/29 Robert Charies Quarmhy, both of 823% gfi gf gg gig Mans Primary ExaminerLowell A. Larson Attorney, Agent, or Firm-Ralph D. Gelling; Vincent [73] Assignee: The British United Shoe Machinery A, Whit Ri hard B. Megley Co. Ltd., Leicester, England [22] Filed: Jan. 15, 1973 [57] ABSTRACT PP 323,391 The invention relates to machines for use in forming attaching loops in generally longitudinal orientation at 30 Foreign Application priority Data or from end portions of coil springs. An end portion of Jan 21 1972 Great Britain 2914/72 a spring is located axially of a machine axis and transversely of a machine axis by locating means of the machine. The machine also comprises orientating means g ggf for facilitating orientation of the spring about the ma- [58] Fieid 316/29 chine axis so that the end of the wire of which the spring is formed is correctly positioned. The machine [56] References Cited further comprises looping means for operating on the located and orientated end portion of the spring to UNITED STATES PATENTS form a loop of a desired configuration and orientation. 2,748,829 6/1956 Korenak 72/37 2.776.696 1/1957 Meier 72/37 1 Claim, 12 Drawing Figures PATENTEDMIB 6mm SHEET 1 [IF 9 PATENTEB AUG 6 I974 SHEET 3 BF 9 PATENTED RUB 6 3 SHEET S 0F 9 PATENTEU AUG 5 I974 SHEET 7 [IF '9 MANUFACTURE OF SPRINGS BACKGROUND OF THE INVENTION Coil springs are frequently required to have a loop at one or both of their ends, which loopis often formed by one or more end coils of the spring being bent out of alignment with the remainder of the coils. This bending of the end coil or coils may be carried out by using known looping machines or by the use of a handoperated tool. It is necessary in order to obtain a correct loop, for the tools of a machine or the handoperated tool to operate on the wire of the spring at the correct points, with respect to the actual end of the wire of which the spring is formed, on the springs periphery. In order to ensure that the tools operate at the correct points it is necessary to locate and orientate the spring so that the end to be looped is correctly positioned.

Known methods of locating and orientating springs for looping are generally unsatisfactory when used with springs of small diameter e.g., less than three-sixteenths of an inch in diameter.

Commonly, small diameter springs are looped using hand-operated tools. To locate and orientate the tool and the spring correctly a bright light and a magnifying glass are used to aid the operator is seeing the spring, and the spring is positioned in the correct position by the operator who relies on his own judgment; this is a highly skilled operation. While satisfactory looping may be achieved in this manner the rate of production tends to be low and the operators tend to suffer from eye strain necessitating frequent rests; also the reject rate is high because of the high degree of skill required of the operator.

An object of the invention is to provide an improved machine for forming loops at or from end portions of coil springs, especially springs of small diameter.

SUMMARY OF THE INVENTION The present invention in one aspect thereof contemplates a machine for use in forming attaching loops in generally longitudinal orientation at or from end portions of coil springs. The machine comprises looping means or tools for operating on the wire of the spring to form the loop, locating means for locating the spring with respect to the looping means in correct location thereto both axially of a machine axis and transversely of the machine axis. The machine further comprises orientating means for facilitating orientation of the spring about the machine axis comprising a projection system by which an image of the end portion of the spring is projected on to a screen.

In a preferred embodiment the projection system comprises an adjustable pointer to indicate the desired position on the screen of the image of the end of the wire of the spring and also a light pipe for conducting light of high intensity to illuminate the end portion of the spring: use of a suitable light pipe prevents excessive heat also being focussed on the end portion of the coil spring.

In a preferred embodiment of the invention the locating means comprises a transparent plate against which the end portion of the spring abutsfor locating the spring axially of the machine: preferably, the plate is adjustable axially of the machine so that loops can be formed on a variety of springs having different wire thicknesses. The plate is transparent to facilitate the operation of the orientating means while the spring is located by the locating means.

Preferably a machine in accordance with the invention comprises holding means including jaw members by which the spring may be gripped, after it has been located and orientated, to maintain the spring in the located and orientated position during operation of the looping means so that the loop is formed correctly. Preferably the holding means also comprises adjustable limiting means for setting the innermost position of the jaws according to the diameter of the spring so that the spring is gripped by the jaws in the operation of the machine to maintain it in position but not gripped so tightly as to deform the spring, and for setting the outermost position of the jaws so that the jaws only travel outwardly a sufficient distance to release the spring being oprated on, thereby assisting in keeping machine cycle as low as possible.

There now follows a detailed description, to be read with reference to the accompanying drawings, of a machine for forming a loop at an end portion of a coil spring, which is illustrative of the invention. It will be understood that this machine has been selected for description by way of example and not by way of limitation of the invention. The principles and features of this invention may be employed in numerous and various embodiments without departing from the scope of the invention.

DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 is a perspective view of the machine in accordance with the invention for forming a loop at an end portion of a coil spring;

FIG. 2 is a sectional view of the machine showing a projection system thereof, having some parts omitted;

FIG. 3 is a plan view of part of the machine with a supporting plate thereof removed and showing some parts in section;

FIG. 4 is a sectional view of the machine taken on the line IVIV in FIG. 3;

FIG. 5 is a plan view taken on a higher level than that of FIG. 3 showing detail of holding means of the machine;

FIG. 6 is a sectional view of an air motor of the machine;

FIG. 7 is a sectional view taken on the line VII-VII in FIG. 5;

FIGS. 8-11 show the operation of the machine to form a loop; and

FIG. 12 shows a spring with a loop formed at an end portion thereof such as is produced by the machine.

DESCRIPTION OF THE ILLUSTRATIVE MACHINE The illustrative machine is mounted in a containing box 2 having side walls 4, a base plate 6, an angled face 8, a top plate 10 and a supporting plate 12. A circular hole is cut out of the supporting plate 12 and into this is set from above a circular plate 14. This plate M has a conical depression 15 in its upper surface and at a central region thereof and at the bottom of this depression 15 a circular hole 16 passes through the plate 14. The conical depression 15 is intended to aid in inserting springs into the hole 16.

The hole T6 is of sufficient diameter that springs to be looped may be inserted therein by an operator and lies with its central axis on a machine axis 55 of the illustrative machine. The arrangement is such that a spring 19 inserted in the hole 116 lies with its axis approximately on the machine axis with a lower end portion of the spring 19 abutting a glass plate i8 which is held by a clamp 20 which is in turn held on a piston rod 21 projecting from an air motor 22. The air motor 22 is pivotally mounted on a bracket 24 supported on the supporting plate 112 and is arranged to operate to position the glass plate 18 in alignment with the hole 16 or, as part of removing means, to remove it from that posi tion by withdrawing it towards the air motor 22 carrying the glass plate 18 and the clamp 26 on its piston rod 21. The distance, which the glass plate 18 is below the hole 16 when it is in alignment with it, may be varied" by means of a screw 26 which is threadedly received in a block 25 which is attached to the air motor 22 by three screws 28 (only one visiblein the drawings). The block 25 has two projections 31 which act to guide the clamp 20 as it is carried to and fro by the piston rod 21 of the air motor 22. The screw 26 passes through a compression spring 27 and passes through a hole in the supporting plate l2 so that the screw 26 can be turned from above the supporting plate 12. Turning the screw 26 acts to pivot the air motor 22 and thus the clamp 20 altering the distance the glass plate 18 is below'the supporting plate 112. The compression spring 27 acts to urge the air motor 22 away from the supporting plate 12 and a head portion 29 of the screw 26 abuts the upper surface of the supporting plate l2 and acts to limit the movement of the air motor away from the supporting plate 12 under the influence of the spring 27. A stop 30 is attached to the underside of the supporting plate H2. The glass plate 18 is set in alignment with the hole 16 at a distance from the upper surface of plate 12 determined so that, when a spring l9 inserted in the hole 16 abuts it, the end portion of the spring 19 is generally correctly located axially of the machine axis for a looping operation to be performed thereon. This distance is such that the desired number of coils of the spring l9 will be operated on by looping means, in the operation of the illustrative machine. Locating means for the spring thus comprises the glass plate 18 and the hole l6.

Below the levels to which the glass plate 18 may be adjusted and also below the hole 16 is a lens system 32 (see FIG. 2) consisting of a doublet of convex lenses. The lens system 32 comprises two acrylic lenses of focal length approximately 25 mm and is corrected for spherical aberration. Lenses of this type are obtainable from Combined Optical industries Ltd of Bath Road, Slough, Buckinghamshire under designation Type S1008(AA). The position and focal length of this lens system 32 is so arranged that light reflected from the end portion of the spring 19 when it abuts the glass plate 118 is passed through the glass plate 18 and the lens system 32 and is reflected by two plane mirrors 34} and 36, mounted on supports 35 which rest on the base plate 6, on to a screen 38, which is also supported by the supports 35 and is positioned parallel to and adjacent the angled face 8, to form a magnified image thereon, the magnification obtained being approximately 15. The screen 38 is made of a suitable translucent material, for example single matt drawing paper of the type Ozatex 005 S/M or of treated glass, so that the image can be viewed from outside the box 2. A pointer 39 is engraved on a piece of plane transparent glass 37 set into face 8 and adjacent and parallel to screen 38 and the glass 37 is arranged to be rotated. This pointer 39 is designed to be used to indicate the desired position on the screen 38 that the image of the end portion of the spring T9 to be looped should occupy and in particular the position the actual end of the wire of which the spring i9 is formed should occupy. A second pointer may be provided if it is desired to use the illustrative machine for springs coiled with eibher a righthanded or a left-handed thread to save unnecessary rotation of the glass 37. The illustrative machine may be used without modification for looping either type of spring the only difference being in the orientation required. An alternative arrangement would be for the screen 33 to have cross-wires associated with it.

The projection system consisting of the lens system 32 and the mirrors 34 and 36 requires a considerable quantity of light in order for the image to be clearly visible through the screen 38 and the glass 37; to this end a light pipe 4d brings light from a lamp 32 mounted on the base plate 6 and shines it directly on to the end portion of the spring 19. The lamp 42 is provided with an ellipsoidal reflector 4 4 which focuses the light from the lamp 42 on to one end of the light pipe 44) in order to ensure that the maximum light reaches the screen 38. The light pipe 410 is a 6mm diameter solid image con duit obtainable from Rank organisation Rank Taylor Hobson Kershaw Division, 200 Harehills Lane, Leeds 8. The lamp 42 is Philips Type 7724, 12 volts, watts. The reflector 44 is a Thorn Lighting ellipsoidal dichroic coated OF. 25 obtainable from Thorn Electrical Industries Ltd. The mirros 3%.36 are surface silvered and are obtainable from English Glass Co. Ltd, Scudamore Road, Leicester and give approximately 90 percent reflection. The use of this means of illumination provides a high intensity of light on the end portion of the spring (necessary to obtain an adequate image) but ensures that little heat is focussed on the end portion of the spring (small springs are easily damaged by two much heat).

Set into the same hole as the circular plate l4 but from below the supporting plate 112 is a bearing member 50 in the form of a ring. The member 50 has a hole through its centre which continues the hole 16 in the plate 114 but is of larger diameter. On its upper surface member 50 has an upstanding ring shaped projection 52 which is centred on the hole 16 and the upper surface of which abuts the lower surface of the plate M. An exterior surface 53 of the projection 52 abuts the supporting plate 112 but between the inner surface of the projection 52, the upper surface of the member 5t) and the plate 14 anannular shaped space 5 remains. Three grooves 56 are cut into the upper surface of the member 50 being cut through the projection 52 as well, these groo,es 56 being at angles of from each other and each lying radially of the hole 16. The grooves 56 narrow towards their end which is nearest to the hole 16, each having a step in them. Three jaw members 58 are slidably mounted in these grooves 56. The jaw members 58 each narrow in a step to conform to the steps in the grooves 56 and each has a downward projection 59 at their end portions which are nearest to the hole 16. These downward projections 59 are accommodated in the hole in the centre of the member 50. The jaw members 58 are so arranged that they can be slid to grip the spring 19 at the level of the member 50.

A cam ring is contained in the space 54 and is free to perform limited rotational motion about the hole 16, therein. Three eccentric slots 62 are cut through this ring 60 and studs 64 are fitted into these slots 62. Each stud 64 is rigidly fixed to one of the jaw members 58. The arrangement is such that rotation of the cam ring 60 causes the studs 64 to slide along the slots 62 and the jaw members 58 to be slid along their grooves 56 either towards or away from the spring 19 contained in the hole 16 depending on the direction of rotation of the ring 60. The distance that the cam ring 60 can rotate is limited by the length of the slots 62. A stud 66 is set into the cam ring and passes through a slot 68 in the bearing member 50 and into a groove 70 in a lever member 72.

The lever member 72 is pivotally mounted on a pin 73 under the supporting plate 12 and the groove 70 is at an end portion of the lever member 72. The groove 70 allows sufficient clearance to the stud 66 to allow for motion of the lever member 72 about its pivot causing the groove 70 to move in an arc centred away from the centre of rotation of the cam ring 60. At the other end of the lever member 72 is disposed a control means 74 comprising a pair of stops 76 carried on a support 78 mounted for sliding movement along a slot 80 in the supporting plate 12. The support 78 is arranged to be moved along the slot 80 and be clamped into position by rotation of a screw 82. The distance between the stops 76 is fixed and the arrangement is such that motion of the end portion of the lever member 72 from one stop 76 to the other causes the jaw members 58 to move sufficiently to grip or release the spring 19. The location of this movement is determined for springs of different diameter by movement of the stops 76 along the slot 80. A scale 81 is provided to aid with location of the stops 76. This arrangement prevents unnecessary time consuming motion of the members 58 and prevents the jaw members 58 crushing the spring 19. A projection 84 of the lever member 72 extends radially of the pin 73 and is attached at its end remote from the pin to a piston rod 85 projecting from an air motor 86. The air motor 86 is pivotally mounted on a bracket 88 on the underside of the cover plate 12 and is adapted to swing the lever member 72 and thus rotate the cam ring 60 to cause the jaw members 58 to slide.

A pivot pin 90 is mounted under the supporting plate 12. On this pin 90 are pivotally mounted two

support members

92 and 94 which are mounted to pivot independently. The

support members

92 and 94 both project radially of the pin 90 and the arrangement is such that the projection of the member 92 is at the same level as the projection of the member 94. A slot is cut in each of the projections of

members

92 and 94 and in each of these slots is supported a pair of

support rods

96, 98. The support rods 96 are supported by the member 92 and the rods 98 are supported by the member 94. These pairs of

rods

96 and 98 are held in slots provided in the projections of each

member

92, 94 and are clamped in position by studs 100.

The rods 96 support at their ends which are remote from the support member 92, an anvil block 102. The anvil block 102 is disposed below the supporting plate 12 and is supported from below by a double bracket 104 on which it rests so that it does not sag away from the supporting plate 12, so bending the rods 96. The

anvil block 102 constitutes one of the three looping tools which act together in looping the spring 19 in the illustrative machine. The anvil block 102 is positioned so that as the support member 92, the rods 96 and the 5 block 102 pivot about the pin 90, a face 106 of the v anvil block 102 moves below the hole 16. The support member 92, the rods 96 and the block 102 are pivoted about the pin 90 by the action of an air motor 108 to a piston rod 109 of which is attached a circular cam 0 member 110. The cam member 110 abuts a face 112 of the anvil block 102 and a face 114 of a block 116 mounted on the underside of the supporting plate 12. The faces 112, 114 of the

blocks

102, 116 are held against the member 110 by a spring 118. The faces 112 15 and 114 are at an acute angle to one another so that movement of the cam member 110 carried on the piston rod of the air motor 108 acts to cause the anvil block 102 to move towards or away from the face 114, pivoting about the pin 90 and this causes the face 106 to move below the hole 16. The air motor 108 is mounted on the underside of the supporting plate 12 on a dovetailed shaped slideway provided by a plate-like extension portion 117 of the block 116 which is secured to the supporting plate 12. The air motor 108 is arranged to slide towards or away from the hole 16 along the slideway. A locking screw 122 is threadedly received in the wall of the air motor 108 and passes through a slot 124 in the extension 117 and the sup- 30 porting plate 12. Tightening of the locking screw 122 acts to lock the air motor 108 in position on its slideway. This slot 124 allows for limited movement of the air motor 108 along the slideway. An adjusting screw 126 is threadedly received in a block 128 mounted on 5 the air motor 108 and is supported for rotation in a hole in a block 129 mounted on the supporting plate 12. The screw 126 when turned acts to slide the air motor 108 along its slideway. Adjustment of the position of the air motor 108 acts to alter the path taken by the cam mem- 40 ber 110 when it is moved by the piston rod of the air 45 ent arcs to be swept out by the face 106 without the stroke of the air motor 108 being altered. A scale may be provided to aid in adjusting the screw 126.

The support rods 98 support a block 130 on which is mounted a striking tool 132 which also constitutes one 50 of the three looping tools of the illustrative machine.

The striking tool 132 is arranged to be moved under the hole 16 in substantially the same way as the face 106 of the anvil block 102. Accordingly the block 130 is supported by a bracket 134 to prevent it from sagging. Pivoting of the support member 94, the rods 98, the block 130 and the tool 132 about the pin 90 is effected by an air motor 136. A cam member 138 abuts a face 140 of the block 130 and a face 142 of a block 144 having a plate-like extension 145 providing a slideway mounted on the underside of the supporting plate 12. The faces 140, 142 are held against the member 138 by a spring 146. The faces 140 and 142 are disposed similarly to the faces 112 and 114 and the action of the air motor 136 is similar to that of air motor 108. A locking screw 150, a slot 152, an adjusting screw 154 and blocks 156 and 157 are associated with the air motor 136 and are generally similar in form and arrangement with the

parts

120, 122, 124, 126, 128 and 129 associated with the air motor 198.

A pivot pin 158 is mounted under thesupporting plate 12 in a position equidistant from the hole 16 as the pin 90 but on the opposite side of the hole 16. A

support member 1611 generally similar to the

support members

92 and 94 pivots about this pin and supports a pair of supporting rods 162 held in position in a slot in thesupport member 160 by a stud 164 similar to the studs 100. Therods 162 support a'block 166 on which is mounted a coil-opening tool 168. The coil-opening tool constitutes one of the three tools'of the looping means of the illustrative machine. The block 166 is pre vented from sagging by the end of the double bracket 104 remote from the anvil block 102. The coil-opening tool 168 is arranged to be moved below the hole 16 in a similar manner to the anvil block 102 and the striking tool 132. Accordingly pivoting of the support member 160, the rods'162, the block 166 and the coil-opening tool 168 about the pin 158 is effected by an air motor 178 and associated with the air motor 170 are a cam member 172, a block 174 having an extension 175, a spring 176, a locking screw 180, a slot 182, an adjusting screw 184 and blocks 186, 187. The form and operation ofthe

parts

172, 174, 175, 176, 180, 182, 184, 186 and 187 is generally similar to

parts

110, 116, 117, 118, 122, 124, 126, 128 and 129 respective. The cam member 172 abuts a face 188 of the block 166 and a face 190 of the block 174.

Description of Method of Operating the Illustrative Machine In the operation of the illustrative machine an operator first adjusts the machine to suit the particular kind of spring he requires to loop and the particular type of loop he requires to impart thereto. He turns the screw 26to adjust the height of the glass plate 18. He turns the adjusting screws 126, 154 and 184 (having first released the

screws

122, 150 and 180) to determine the distance each of the

tools

102, 132 and 168 will move under the hole 16, thus determining the type of loop. He then locks the

cylinders

108, 136 and 170 in position with the

screws

122, 150 and 180 respectively. He adjusts the position of the support 78 of the stops 76 in the slot 80 and locks it in position thereby predetermining the motion of the jaw members 58. He also adjusts the position of the pointer 39 to the correct position.

After adjusting the illustrative machine the operator takes a spring to be looped either by hand or in a holder and inserts it into the hole 16. The end portion of the spring abuts the glass plate 18 which is at this time in the operation of the machine disposed below the hole 16. For springs made of thin wire the distance the glass plate 18 is below the plate 12 requires to be less than for those made of thick wire. The adjustment of the screw 26 must ensure that sufficient coils of the spring extend below the hole 16 to allow the jaw members 58. and the

tools

102, 132 and 168 to operate thereon.

When the end portion of the spring abuts the glass plate 18 an image of the end portion of the spring appears on the screen 38 as the end portion is then approximately in focus of the lens system 32. An adjusting screw 192 is provided to tilt the plate 12 about a hinge 194, the purpose of this screw 192 is to allow focussing of the projection system by slight adjustment of the position of the plate 12 and hence of the spring 19. In

order that the image may be clearly visible the lamp 42 requires to be switched on and this lamp 42 may suitably remain on throughout the period of operation of the machine. Using the image on the screen 38 to guide him the operator twists the spring 19 to orientate the end of the wire of which the spring 19 is formed with respect to the

tools

102, 132 and 168. To further facilitate thisorientation the operator uses the pointer 39 whose position has been adjusted to indicate the correct orientation for the particular type of loop. If the spring 19 is considerably smaller in diameter than the diameter of the hole 16, it may require to be moved to a more central position in the hole also with the aid of the image on the screen 38. However the spring 19 need not be positioned dead centre by the operator as the jaw members 58 act to centralise it as they grip it, so that the axis of the spring 19 lies on the machine axis 55. The control means 74 is previously adjusted in its slot 80 to suit the diameter of the spring 19.

When the operator has oriented the spring 19 to his satisfaction he presses a control and thereby operates the holding means and the looping means. A pneumatic circuit (not shown) supplies air to the air motor 86 causing the lever member 72 to pivot and the cam ring 60 to rotate; this acts to move the jaw members 58 towards the spring 19 to grip it so that it is held in its located and orientated position. Next the air motor 22 operates to remove the glass plate 18 from below the spring 19 so that it does not interfere with the operation of the looping means (this situation is shown in FIG. 8).

The looping means operates next by air motor 178 causing the coil-opening tool 168 to approach the spring 19 and lift the end coil of the spring 19 away from the next coil (this is shown in FIG. 9); with certain types of loop it may be necessary for the coil-opening tool 168 to lift two or more coils of the spring and the illustrative machine may be used to do this by adjustment of the distance the glass plate 18 is below the hole 16 when the spring 19 is inserted.

After the coil-opening tool 168 has bent the end coil of the spring 19 and while the tool 168 remains in position the anvil block 102 is moved towards the spring 19 by the action of the air motor 108. The face 186 of the anvil block 102 contacts the lifted coil of the spring 19 and bends it further away from the rest of spring 19 (see FIG. 10). The anvil block 102 is provided with a slot 196 therein in which the coil-opening tool 168 passes when it advances or retracts so that the two tools do not interfere with each others operation. Depending on what type of loop is required the anvil block 1112 may move to the machine axis 5 or even beyond the far side of the spring 19.

After the anvil block 102 has completed its forward motion and while it remains abutting the bent end coil of the spring 19, the striking tool 132 is moved towards the spring 19 by the action of air motor 136 and as it advances the coil-opening tool 168 returns to its original position (see FIG. 11). The striking tool 132 strikes the bent coil of the spring 19 and forces it against the anvil block in such a manner that after withdrawal of the anvil block 102 and the striking tool 132 the bent coil will remain bent forming a loop at the end of the spring 19. The striking tool 132 then returns to its original position and then so does the anvil block 1112.

The illustrative machine now pauses in its operation to allow the operator to take hold of the unlooped end of the spring 19 and then the air motor 86 acts to release the grip of the jaw members 58 and return them to their original positions. The operator takes the spring 19 out of the hole 16 and then the air motor 22 acts to replace the glass plate 18 under the hole 16 so that the illustrative machine is ready to loop another spring 19 of similar type.

It is found that, by using the illustrative machine, springs of small diameter e.g., between three-sixteenths inch and one-sixteenth inch can be satisfactorily looped with a low reject rate, at a satisfactory production rate and without undue eye strain being caused in an operator thereof.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

l. A machine for forming a loop at an end portion of a coil spring comprising:

A. Means for engaging an end of the spring to form a loop thereon;

B. Means for accurately adjusting the location of the spring with respect to the loop forming means, both axially and transversely of a machine axis;

C. A source of light mounted to direct a beam of light on the end portion of the spring;

D. A transparent supporting plate which engages the end portion of the spring and is adjustable to vary the position of the spring; and

E. A projection system mounted to receive light reflected from the end portion of the spring through the transparent plate and transmit a magnified image of the end portion of the spring onto a screen to facilitate positioning of the spring.

Claims

1. A machine for forming a loop at an end portion of a coil spring comprising: A. Means for engaging an end of the spring to form a loop thereon; B. Means for accurately adjusting the location of the spring with respect to the loop forming means, both axially and transversely of a machine axis; C. A source of light mounted to direct a beam of light on the end portion of the spring; D. A transparent supporting plate which engages the end portion of the spring and is adjustable to vary the position of the spring; and E. A projection system mounted to receive light reflected from the end portion of the spring through the transparent plate and transmit a magnified image of the end portion of the spring onto a screen to facilitate positioning of the spring.