US2774407A - Methods of and machines for winding spiral springs - Google Patents

Description

1956 w. .1. B. JANSEN 2,774,407

METHODS OF AND MACHINES FCR WINDING SPIRAL SPRINGS 7 Filed April 26 1951 3 Sheets-Sheet 1 INVENTOR ATTORNEYS.

Dec. 18, 1956 v\ J. B. JANSEN METHODS OF AND MACHINES FOR WINDING SPIRAL SPRINGS 3 Sheets-Sheet 2 Filed April 26, 1951 INVENTOR:

BY W v M/6M ATTORNEYS.

Dc. 18, 1956 w. J. B. JANSEN METHODS OF AND MACHINES FOR WINDING SPIRAL SPRINGS Filed April 26, 1951 3 Sheets-Sheet 3 1N VENTOR I ATTORNEYS.

United States Patent IWETHODS OF AND MACHINES FOR WINDING SPIRAL SPRINGS Willem J. B. Jansen, Paris, France Application April 26, 1951, Serial No. 222,973

Claims priority, application Switzerland April 27, 1950 7 Claims. (Cl. 153-65) This invention relates to methods of and machines for winding springs of spiral form, and particularly to methods and machines which do not include a mandrel for forming the springs.

Objects of theinvention are to provide methods of and apparatus for winding springs by forcing a flat band of spring material against and tangentially along spaced surfaces of a shaping tool to bend the band into spiral shape. Objects are to provide methods and apparatus of the character stated in which the shaping tool includes at least two abutments with guiding surfaces for bending the band, and in which the abutments are moved apart during a spring winding operation to increase the radius of bending as the length of the spring is increased. Other objects are to provide spring winding methods and machines in which a flat strip or band of rectangular cross section is forced tangentially over four guiding surfaces to bend the strip or band into a flattened spiral form such that, on relief of the bending force, the wound spring assumes the form of an Archimedean spiral.

These and other objects and the advantages of the invention will be apparent from the following specification when taken with the accompanying drawings, in which:

Figs. 1 and 2 are diagrammatic views showing the relative positions of spring winding apparatus embodying the invention at the beginning and at a subsequent stage, respectively, in the winding of a spiral spring;

Fig. 3 is a geometrical diagram showing the theoretically appropriate relative position to which the guiding surfaces of parts of the shaping tool should be moved at different stages in the winding of a spiral spring;

Fig. 4 is a side elevation, as seen with one side plate removed, of a shaping tool for operation in accordance with the Fig. 3 graphical solution;

Fig. 5 is a vertical section through the shaping tool as taken on section line 5--5 of Fig. 4;

Fig. 6 is a side elevation of a winding machine embodying the invention;

Fig. 7 is a fragmentary plan view of the shaping tool and its adjustable support;

Figs. 8 and 9 are fragmentary side elevations, with parts in section, of another shaping tool assembly embodying the invention and showing, respectively, the apparatus at the start and at a subsequent stage in the winding of a spring; and

Fig. 10 is a fragmentary side elevation, with parts in section, of a modified form of shaping tool assembly.

In the drawings, the reference numerals 1 and 2 identify the cooperating rollers of a mechanism for feeding a strip 3 of spring stock of rectangular cross-section in the direction of the arrow 4. The strip is fed through a nozzle shaped guide 5 and forced against the inclined guide surface 6 of a shaping jaw 7. The shaping tool includes a guide 8 which extends above the jaw 7 and has a shaping surface normal to the direction of strip feed, and an upper jaw 9 having a guide surface inclined oppositely to the guide surface 6 of the lower jaw 7. Each guide surface deflects and bends the strip material clock- Wise as it is forced against and slides along the guide surfaces, thus forming a closed loop 10 when, at the start of the winding operation, the jaws 7 and 9 are close to each other and are held stationary until the loop is completed, Fig. 1.

The radius of curvature is increased when the shaping tool is moved further from the feed rolls 1, 2 and the feed nozzle 5 and, at the same time, the shaping jaws 7 and 9 are moved apart. By a progressive separation of the shaping jaws as the shaping tool is moved away from the feed rolls, the curvature imparted to the strip material changes progressively and a spiral spring 11 is formed,

see Fig. 2. The spring diameter is equal to the difference between the final spacing y of the shaping tool from the feed rollers and the initial spacing x. The movements of the parts must of course be properly coordinated and synchronized in any machine which automatically performs the winding operation.

The conditions to be fulfilled could be determined mathematically but they may be adequately analyzed and determined graphically by means of the Fig. 3 diagram in which the blocks 7a, 8a, and 9a indicate the initial positions of the several shaping tool parts, and the blocks 7b, 8b and 9b indicate the corresponding final positions. These end positions correspond respectively to the initial and final bending circles a and b for strip material which is forced towards the shaping surfaces along the same line and in the direction indicated by the arrow 12. Several intermediate positions of the parts are shown but are not separately identified by reference numerals.

All bending circles are tangent to the horizontal line of strip feed and also to the shaping surfaces in their several positions corresponding to the individual bending circles. From an initial circle, which can be assumed to be infinitely small and to correspond to point A, a line AB is drawn diametrically through the severalcircles, this line being perpendicular to the shaping surface of the jaw 9. A line B'C drawn parallel to the direction of strip feed and through the center B of circle b will be perpendicular to the surface of guide block 8a and will bisect the angle BB-C between the line AB and a radius B'C perpendicular to theguide surface of the jaw 7. Lines B'D and B'E drawn from the center B of the b-circle to the intersections of the surface of guide 8a with the surfaces of the upper and lower jaws 9a, 7a respectively, make equal angles with the radius B'C, and, it can be proved that these intersections for all intermediate circles will fall upon straight lines AD and AE respectively.

The lines AD and AE afford a graphical solution for the problem of determining the progressive movements of the parts 7, 8 and 9 of the shaping tool in winding a spiral spring having an inner loop with the curvature of circle a and an outer spiral turn 13 with the curvature of circle b. This solution is accurate, however, only in the case of strip material such as lead having only a small degree of elasticity, and the theory must be modi fied in view of the high elasticity of the strip material of the springs. The material as bent to arcuate form by the jaw 7 and guide member 8 would slide along the shaping jaw 9 with little or no bending when forced towards the shaping tool in the direction indicated by the arrow 12, and the spring would expand greatly when removed from the shaping tool. The unstressed form of the spring would not be that of an Archimedean spiral with a uniform spacing between adjacent turns but would be that of a logarithmic spiral with a rapidly increasing spacing of the turns.

This variation of the spacing of the turns can be compensated to a desired extent by modifying the relative geometry of the parts in such manner that the jaw 9 faces.

shaping tool.

functions as a brake on the strip material to press it so .firmly against the shaping surface of the jaw 7 and guide 8 that the limit of elasticity is surpassed and the required permanent change of form is effected by the force required to move the strip material alongthe'shaping sur- The braking action or increased frictional resistance at the jaw 9. can be obtained in a simple manner by increasing the normal pressure of the strip material upon the jaw 9, i. e. by increasing the angle between the shaping surfaces of the guide 8 and jaw 9 to considerably more than the 45 angle shown in Fig. 3.

V A shaping tool for winding springs from elastic spring material in accordance with the above analysis is illustr'ated in Figs. 4 and 5. Two guideplates 14 and 15 are secured to each other in parallel relation by any known means, and have longitudinal grooves 1.6 along their lower opposed surfaces to form a rectilinear'guide for a slide 17which carries a vertically slotted guide piece 18.

Pins Hand extend through the guide piece slot and through grooves 21 .and22 respectively in the guide plates 14, 15., Shaping jaws 23, 24 are slidably supported on the guide piece 18 by the pins 19, 20 respectively which effectvthe desired displacements of the jaws on movement of the slide 17 since the guide grooves 21 and 22 are inclined to the direction of strip feed according to lines A--E and A-D of Fig. 3. 'As shown .in Fig. 4, the guide piece 18 forms the central part of the dined at an included obtuse angle of, for example, 135

' to the direction of strip feed and has an included angle with the shaping surface of guide member 18 of 135. The shaping surface of the jaw 24 is inclined at an angle of, for example, 30 to the direction of strip feed and has an included obtuse angle with the shaping surface of guide member 18 of 120". Due to this smaller included .angle between shaping surfaces, the shaping surface of a jaw 24 provides the braking or increased frictional resistance referred to above, causing the limit of elasticity of thestrip to be surpassed and the required permanent change of form to be efiected. A spring 25 is connected between the slide and a pin 26 fixed to guide plates to pin 27, which is fixed to the slide, in contactwith a pin 28 of mechanism for'synchronizin g the slide tool adjustments to the feed of the spring material. For clarity, the position of slide bar 42 has been shown in dotted lines in Fig. 5.

'A winding machine including the described shaping tool assembly is shown in Fig. 6. A frame 29 carries a strip feed mechanism comprising rollers 30 and 31, the

. roller 31 being supported by a lever 32 on a rock shaft 33 mounted on the frame 29, the lever tbeing yieldingly urged counterclockwise by a spring 34 -to press the roller '31 against roller 30. The rollers are connected by gear tram 30', to rotate in opposite directions and at the same speed when the lower roller is turned, for example, by a crank arm, not shown, at the rear side of the frame. .The feed rollers force the strip material 35 to the left,

as shown by the arrow, through a stationary nozzleshaped guide 5' and into a shaping tool assembly 36 as illustrated in Figs. 4 and 5. The lever 32 may be tilted to relieve the pressure on the feed rollers by the spring 34, for example by means of a cable 37 and foot lever bar 42, and its position may be changed by an adjusting screw 43 so that the distance between the shaping tool and the roller feed may be altered. The shaft 39 carries The shaping surface of the jaw 23 is in-' 2,774,407 V V r i a graduated dial 44 for indicating, by referenceito an index mark 44a fixed to the frame 29, the length of the at the completion of a winding operation and to prevent V draw the slide towards the left, Fig. 4, to maintain the material fed into the shaping tool. The gearing for driving the shaft 39 includes 'a small gear on the shaft of the roller 30, a much larger gear on the shaft 39, and a movable gear or clutch operable in known manner to break the driving connection to reset the slide bar 42 automatic movement of the slide bar when, aswill be described later, the machine is adjusted to wind helical springs. V

A scale 45 is provided on a guide plate of the shaping tool, and a pointer 45a is secured to the slide 17, or its pin 27, and moves along the scale 45'l0 indicate the position of the slide within the guide plates.

As shown in Figs; 4 and 7, the forward edge of the shaping tool 36 is supported by a plate or disk 46 which, in turn, is carried by a shaft 46'journalled on therframe 29 and may be turned angularly to adjust the orientation for winding springs ofdifferent forms are as follows;

For fiat spiral springs, the slide17of the shaping tool 36 is adjusted by the plate 46 into alinementwith the direction of material feed, the free end of the strip material 35 from reel 38 is inserted between the feed rollers 30, 31, the free end is bent slightly upward by hand or by, some auxiliary device, and the feed roller 30 is rotated to-force the strip 35 into the shaping tool. The strip is consecutively bent into coil form by the three shaping surfaces, and the slide of the shaping tool is moved away from the feed rollers by spring 25 at a rate, with respect to the strip feed, determined by the shape of the cam '40. The lengthof the strip introduced into the shaping tool is indicated by the dial 44 and the diameter of the spiral coil can be readfrom the scale 45. When the winding operation is completed, pressure is applied to the foot lever 37' to lift the feed roller 31 so that the shaping tool slide may be moved away from the feedrollers without feeding additional material into the shaping tool 36. The wound spring is cut from the strip 35 and removed from the shaping tool. The machine is reset by opening the drive connection to the cam shaft 39, returning the slide bar 42'to initial position, and re-coupling the gearing.

To wind helical springs, the gear driveto the cam 40 is opened and the slide bar 42 is clamped bythe handwheel 48 and stud 49, thus preventing movement of the slide and jaws of the shaping tool during the winding operation. The diameter of the helical springs is'indicated on the scale 45, and the pitch of the helix is determined by the angular setting of the shaping tool as indicated on the scale 47 Another shaping tool which includes a larger number of shaping surfaces and is better adapted for use with various types of spring material and for the formation of Archimedean spirals is shown in Figs. 8 and 9. The

shaping tool comprises two stationary jaws 56. and 51 with guide or shaping surfaces 52, 53. respectively, and two movable'shaping members 54, 55 with shaping surfaces 56, 57 respectively. The jaws 50, 51 are stationary and may be parts of the machine frame, and the guide face 53 coincides with the direction of material'feed and constitutes a bed or track along which the spring strip guide surface 56 inclined or tilted back from the guide surface 53 at a somewhat greater angle than that between the oppositely inclined guide surface 52 and the guide surface 53. The jaw 55 has the form of a sleeve slidable on the jaw 54 and with its guide surface 57 approximately normal to the adjacent guide surface 56. Feed rollers 58, 59 force strip material 60 along and tangentially to the several guide surfaces, and the jaw 55 is moved upwardly on the jaw 54 t the extent permitted by the pin 61 which is fixed to jaw 55 and moves in a slot 62 of the jaw 54, as the jaw 54 is moved away from the feed rollers during a winding operation.

-In winding a spiral spring, the free end of the strip material 60 is bent upwards slightly and then forced against the guide surface 56 of the jaw 54 by the feed rollers 58, 59. The strip will be bent or coiled as it is forced against and along the guide surfaces 56 and 57 until the turned-over end of the loop is momentarily arrested by the guide surface 52, see Fig. 8. The initial spacing of the shaping surfaces 53 and 57 is less than the desired starting diameter of the spiral because of the high elasticity of the material. The coefiicient of reduction may be about 0.6 in the average case, and it is determined experimentally for difierent spring stock as it varies with the characteristics of the materials employed. When, for instance, the inner diameter of the winding is to be mm., the initial spacing between the guide surfaces 53 and 57 is set at 3 mm. because the elasticity of the material will open up the winding loop to 5 mm.

The shaping jaws 54 and 55 slide between guide plates, similar to plates 14, 15 of Figs. 4 and 5, having slots therethrough at an appropriate angle to receive the pin 61 and lift the jaw 55 as the jaw assembly is automatically moved away from the feed rollers by a cam mechanism similar to that shown in Fig. 6. The final bending of the loops or turns is effected between the guide surfaces 52 and 53, and the guide surface 52 is spaced from the opposed guide surface 56 by substantially the winding diameter. The coiled material therefore initially has the form of an ellipse which expands to approximately circular form on release from the bending stress since the limit of proportionality is not exceeded.

For spiral springs of larger diameter, the single sliding jaw 55 is replaced by a plurality of telescoped jaw sec tions 63, 64 and 65 which are slidable upon the first movable jaw 54', see Fig. 10. This construction affords a minimum spacing of the jaw sections from the stationary jaw 66 at the initial stage of a winding operation, and a wide guiding face at later stages as the jaw sections 64 and 65 are moved downward on jaw section 63 by springs 67, 68 respectively as the assembly moves away from the feed rollers. Only the inner jaw section 63 need be subject to the automatic cam control, as previously described, since the movements of the jaw sections 64 and 65 are such that their guide surfaces aline with the guide surface of jaw section 63 in their end positions.

While three telescoped jaw sections are shown in Fig. 10, it will be apparent that the number may be greater or less according to the desired ratio of the diameters of the inner and outer turns of the spiral spring.

It is to be understood that changes may be made in the machine, for example the shaping tool assembly may be stationary and the feed rollers may be moved away from it, and that this and other variations fall within the spirit and scope of the invention as set forth in the following claims.

I claim:

1. The method of winding spiral springs utilizing a series of successively arranged abutments having fiat frictional surfaces inclined with respect to each other comprising the steps of forcing a strip of spring material of rectangular cross-section against and tangentially of a first abutment having a surface inclined at an obtuse angle with respect to the initial direction of strip travel,

forcing the' strip against a second abutment having a surface inclineda't'an angle with respect to the initial direction of 'strip-travelsmaller than said first obtuse angle, forcing the strip against a third abutment having a surface inclined at an acute and even smaller angle with respect to the initial direction of strip travel, the included angles between said three successive abutment surfaces being progressively smaller whereby the frictional resistance of the surfaces causes the strip limit of elasticity to be surpassed resulting in permanent deformation of said strip to curvilinear form, and finally relatively displacing the abutments as the winding progresses to increase the spacing of the regions of the adjacent pairs of friction surfaces contacted by said strip, thereby to increase the spring diameter.

2. A machine for winding spiral springs from a strip of spring material of rectangular cross-section comprising shaping means to bend the strip reversely to the direction of strip feed to form the strip into circulinear form of progressively larger diameter and means for forcing said strip into said shaping means, said shaping means including a series of successively arranged shaping abutments having flat frictional surfaces inclined with respect to each other, one of said abutments having a surface inclined at an obtuse angle with respect to the initial direction of strip travel, a second of said abutments having a surface inclined at an angle with respect to the initial direction of strip travel smaller than said first obtuse angle, and a third abutment having a surface inclined at an acute and even smaller angle with respect to the initial direction of strip travel, the included angles between said three successive shaping abutment surfaces being progressively smaller whereby the frictional resistance of the surfaces causes the strip limit of elasticity to be surpassed resulting in permanent deformation of said strip to curvilinear form, and means for automatically moving a plurality of said abutments with relation to the others of said series and in synchronism with the strip feed to increase the radius of curvature of the bent strip as the winding operation proceeds.

3. A machine for winding spiral springs as defined in claim 2 wherein one of said shaping abutments is a guide member having a guide surface substantially normal to the direction of strip feed and two of said shaping abutments are shaping jaws slidably movable upon said guide member.

4. A machine for winding spiral springs as defined in claim 3 wherein said shaping means comprises guide plates, a slide movable between said guide plates in substantially the direction of strip feed and carrying said guide member, and means supporting said shaping jaws between said guide plates for relative movement with respect to each other and to said guide plates.

5. A machine for winding spiral springs as defined in claim 4 wherein said guide member is provided with a longitudinal slot and said supporting means comprises pins carrying said jawsand extending through the slot in said guide member, and said guide plates have inclined grooves in which the ends of said pins are seated, whereby upon movement of said slide said jaws are moved upon said guide member relative to each other and to said guide plates.

6. A machine for winding spiral springs as defined in claim 4 including means for moving said slide in substantially the direction of strip travel in synchronism with said strip forcing means.

7. A machine for winding spiral springs as defined in claim 6 wherein said slide moving means comprises spring means biasing said slide within said guide plates in the direction of strip travel and control means comprising a cam geared to said forcing means and a slide bar connected to said slide and cooperating with said cam to control the position of said slide with respect to said guide plates.

(References on following page) V 7 References Cited in the file of this patent UNITED STATES PATENTS f l Green -May 21', 1878 Kirk 'Sept; 11-, 1900 5 Herbert Noyl 17, 1908 Fargo 'June 9,- 1914 Knuth Sept. 14, 1926 Sargent -2 Feb.'21, 1928 Germany Nov. 9; 1927 V paw-W

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