FR2533149A1 - Discontinuous wire-driving device. - Google Patents

Abstract

A wire 1 is driven discontinuously by interposition between the edges of two rollers (pulleys) 11 and 12 rotating at equal velocities but in opposite direction, these rollers (pulleys) being adapted for providing between their edges a variable space, sometimes a minimum, sometimes a maximum, so as to apply to the wire, respectively, a frictional driving force which is sometimes positive and sometimes zero. Application to the feed for wire-converting machines, for example for the manufacture of springs.

Description

 The present invention relates to a discontinuous bare wire drive device, in which a wire is interposed between the edges of at least one pair of two centrally rotating rollers rotating in opposite directions.

 The invention applies very particularly in the field of wire transformation, in the case in particular of the manufacture of springs, pins or other metal parts, from wire of suitable characteristics. In this case, the wire is initially packaged in spools of very long length, which must, before any transformation, be cut into lugs- of appropriate length using a cutting device. This device is, to do this, supplied discontinuously by a step-by-step feed device, the different periods of advancement of the wire being separated by stop periods during which the cutting device operates.

 The feed device is generally constituted by means of gripping the wire, in general two "wedges" coming to pinch the wire, moving towards the cutting device by helping the wire in their movement while the cutting device is in the open position, then letting go of the line and returning to their starting position, the line then being stationary while the cutting device cuts it off. Retaining, friction, pinch means coordinated with the advancing device may be necessary to avoid displacement of the wire while the wire gripping means, after release of the wire, return to their starting position.

 Another advancement system is also encountered in practice, namely two cylindrical rollers which pinch the wire to be driven between them, and which rotate step by step by a determined quantity corresponding to the desired advance of the wire, the cutting wire occurring when it is stationary.

 In addition to the risk of the device being out of adjustment under the effect of vibrations which may help to modify the advance length of the wire, the two aforementioned advance devices have the major drawback of being driven by a jerky reciprocating movement preventing high speeds, thus limiting the yield. In addition, the parts which constitute them must be robust, therefore relatively massive and heavy.

 The same kind of difficulties are encountered when, instead of transforming the wire, one wishes to transform parts which are linked to it, by passing them successively through different processing stations.

 The object of the present invention is to overcome these drawbacks and to this end provides a wire discontinuous drive device, in which a wire is interposed between the edges of at least one pair of two drive rollers rotating in opposite directions, characterized in that said drive rollers, continuously assisted in rotation, are adapted to provide between their edges a variable space, sometimes minimum, sometimes maximum, so as to apply to the wire, respectively, a friction training force sometimes positive, sometimes zero. The variations in space between the drive rollers ensure a discontinuous drive of the wire while allowing a continuous and uniform rotation of said rollers. These parts are less stressed mechanically. As for their training, it is more economical since it is regular, without sudden and successive ruptures of driving force. In this way the production rates can according to the invention be significantly accelerated compared to what is currently known.

 The invention preferably provides two drive devices adapted to two main ranges of wire lengths between stops.

 The invention thus provides a device bu type aforementioned in which the drive rollers of each pair are circular discs, at least one of which has on its edge at least one circumferential recess of predetermined angular amplitude. Such a device is applicable to short lengths of wire between stops, always less than the circumference of the disc thus hollowed out. This recess can be achieved by appreciably increasing the size of the groove which is generally arranged in a circle on the edge of the aforementioned disc, or by reducing the radius of said disc until the local disappearance of said groove. The first case provides transverse support wire without entraining it, while the second only involves simple machining techniques for modifying the discs.

 For very close stops it is of course recommended to provide a plurality of recesses on each roller of each pair, these recesses being preferably arranged so as to come alternately opposite the wire so as not to duplicate and reduce at least the number of recesses to be made.

 The invention also proposes a device of the aforementioned type, characterized in that the drive rollers of each pair are circular disks of the same diameter, the first of which, movable, is adapted to move away from the second, fixed , the rotation shaft supporting said movable disc admitting at the latter a transverse clearance. Such a device, barely more complicated than the previous one, is suitable for ensuring any spacing between stops, since it is a kind of "disengagement" between rollers and wire: the latter is no longer driven by friction as soon as the pressure exerted on it by the rollers is released.

 The control of the movable disc is advantageously ensured, directly or indirectly, by a cam, cooperating with a roller, the rotation of which is continuous.

 The invention particularly provides a device in which said roller is carried by a lever which revolves around a fixed pivot parallel to the rotation shaft of the movable disc and one arm of which acts on a declutching roller carried by said shaft. rotation. There is therefore an indirect connection between the cam and the rotation shaft, which makes it easier to organize the device within a given volume. The use of a lever also allows the cam to act in the direction of the spacing of the two rollers, against a pressing device, whereby the "normal" configuration of the rollers corresponds to the wire training. The lever advantageously comprises on a second arm a braking device intended to immobilize the wire when it is no longer in engagement with the drive rollers.

 The invention more specifically recommends that the cam be secured to a driving shaft which centers the rotation shaft of the movable disc by means of a first pair of two toothed pinions secured to these shafts, said disc rotation shaft mobile in turn assisting the rotation shaft of the fixed disc by means of a second pair of toothed pinions integral with these shafts, which corresponds to a fairly simple and reliable structure.

 In the case of supplying wire to a machine, the various operations that said wire must undergo are advantageously controlled by cams linked to the driving shaft, which easily facilitates the synchronization of the movement of the wire and the operations that it undergoes, in particular its cutting.

Other objects, characteristics and advantages of the invention appear from the description which follows, given by way of nonlimiting example, with reference to the appended drawings in which
- Figure l is a side view of a device according to the invention in a first embodiment;
- Figure 2 is a partial sectional view of said device along line II-II of Figure 1
- Figure 3 is a partial sectional view of said device along line III-III of Figure i
- Figure 4 is a variant of Figure 3
- Figure 5 is a perspective view of a device according to the invention in a second embodiment
- Figure 6 is a front view of the cam of the device of Figure 5 according to an alternative embodiment.

 In the first embodiment illustrated by way of a preferred example in FIGS. 1 to 4, the discontinuous drive of a wire 1, fed as felt, as circular with a diameter D1, by means of rollers 11 and 12 in permanent rotation at uniform speed, is ensured thanks to the particular configuration of the latter.

 In the embodiment shown in Figure 1 the two rollers 11 and 12 are identical. They are supported conventionally, at the same speed but in the opposite direction, by gears, toothed belts or other known means, not shown, around respective parallel rotation shafts 11 'and 12'. On their cylindrical edge are formed circumferential grooves 13 and 14. These rollers are oriented one relative to the other so that a clearance is formed between them and that the grooves 13 and 14 cooperate to form a circular housing whose diameter is substantially equal to that of wire 1 (see Figure 2).

 The drive of the wire by the rollers 11 and 12 is obtained by friction; this friction is all the more important that a significant pressure force is exerted on the wire by the rollers. The roller 11 is pushed back towards the roller 12 by a pressing device shown in Figure 1 by a stack 20 of Belleville washers pressed against a support 21 in which the shaft journals ~ 12 'by means of a adjusting screw 22 cooperating with a fixed nut-body 23. By action on the screw 22, it is possible to adjust the driving force to be applied to the wire 1. Such an elastic pressing of the wire between rollers also makes it possible to compensate for any fluctuations in diameter of said wire, or to adapt to several neighboring wire sizes.

 Stops, not shown, limit the approximation by elastic tightening of the rollers 11 and 12 to prevent any contact between them in the absence of wire.

 On the edge of each roller, in addition to the grooves 13 and 14 are provided circumferential recesses -15 of angular amplitude ocpredeter- mined, here less than 1800. The value is chosen so that if R is the diameter of the rollers 11 and 12 at the bottom of the throat, the product (block).

R is equal to the length of wire drive sought between each wire station.

 As shown in Figures 1 and 3, a circumferential recess is a circular groove, concentric with the groove 13 or 14, the diameter D2 is substantially greater than the diameter D1 of the wire. In this way, a space is created between the edges of the rollers which is substantially greater than the cross-section of the wire, preventing any pressing for driving the latter. Taking into account that the flanks i lA, 11B, 12A, 12B of the rollers are not affected, space between rollers, plumb with a circumferential recess, is substantially closed and does not allow any transverse escape of the wire out rollers when not being dragged by them.

 In the variant embodiment shown in FIG. 4, a circumferential recess 15 ′ is achieved by local reduction in the diameter of the roller, this reduction being substantially greater than the size of the groove 13 or 14, thus causing local disappearance of said groove. There is no longer transverse maintenance of the wire but such a recess is very simple to perform.

 In operation of the device of Figure 1, the wire 1 is driven as long as it does not meet any recess 15 on the edges of the rollers 11 and 12 the space between the rollers is then minimal as it appears on Figure 2 which is a partial section of the device of FIG. 1 immediately to the right of the plane defined by the axes of rotation of the two rollers.

 The training of the wire by the rollers ceases as soon as there is a circumferential recess for the wire on the edge of one of the rollers, as it appears in Figure 3 which is a partial section of the device of Figure 1 immediately to the left of the plane of the axes of rotation of the two rollers 11 and 12. The entrainment: of the wire ceases for a time proportional to the angular amplitude of the recess 15 and to the angular speed of rotation of the rollers.

 It should be noted that, in the example in FIG. 1, during a complete revolution of the roller, two step-by-step advances occur, separated by stops caused successively by one then the other of the recesses provided on the edge of the pebbles. These recesses preferably come alternately opposite the wire 1 so as not to duplicate. The respective angular positioning of the two rollers is advantageously such that the successive step-by-step advances of the wire are equal, the entrainment of the wire then being each time on an angular sector, additional to the angle t.

 It is understood that several recesses can be made, if necessary, on each roller. It should be noted, however, that for each pair of rollers 11 and 12 there correspond drive lengths, waiting times and a given wire diameter. It is therefore advisable to choose the rollers to be used according to each use.

 It appears however that, even in the case of a single recess on only one of the rollers, the drive length is at most equal to the circumference of each roller, and that the waiting time between each advance is as much lower than the training length is high. The device of Figure 1 n1 is therefore applicable only in the case of relatively reliable drive lengths, not leading to roller dimensions, therefore to a space, redibhitoires.

 Figure 5 illustrates another preferred embodiment of a device according to the invention, which is valid for any values of opening lengths.

 In this embodiment, the wire 1 to be supported is interposed for clamping between two drive rollers 31 and 32, formed of circular discs of the same diameter, symmetrical with respect to their respective rotation shafts 2 and 3. The first roller 31 is movable in its plane, and is adapted to deviate as a whole from the second roller 32, which is fixed, by virtue of a transverse movement of the rotation shaft 2 of said roller 31 in the plane that it defines with the shaft rotation 3. It is a kind of declutching device in which the wire 1 is driven or not depending on whether it is engaged or not with the drive rollers 31 and 32, except that, unlike d 'A classic clutch, for example for cars, here there is transformation of a rotary movement into a rectilinear movement.

 The device of Figure 5 comprises three shafts 2, 3 and 4 parallel or almost parallel, secured in rotation by two pairs of toothed pinions 41-42 and 43-44. The pinion 41, integral with the shaft 4, called the driving shaft, cooperates for driving in rotation with the pinion 42 secured to the shaft 2, called the first driven shaft. As will appear below, the pair of pinions 41-42 advantageously constitutes a speed multiplier or a speed reducer. The pinion 43, also integral with said first driven shaft 2, cooperates with the pinion 44 integral with the shaft 3, said second driven shaft. The pinions 43 and 44 are identical so that the drive rollers 31 and 32 are rotated with equal speeds but in opposite directions, which is necessary for a good rectilinear drive of the wire, without curvature of the latter. this.

 The driving shaft 4 is rotated by means of a toothed pinion 45 which cooperates with a chain 46 hampered by a motor not shown. This shaft is fixed axially and transversely, journalling in fixed bearings of which only one is shown for reasons of clarity, under the reference 50 the latter is linked to a fixed frame element 51.

 The toothed pinion 42 is carried by a fixed portion 2A of the first driven shaft 2 which rotates in a bearing 52 linked to the same element 51 of the frame. The shaft 2 comprises a movable portion 2B provided with a limited angular movement in the plane of the shafts 2 and 3, by virtue of a spherical bearing 53, of known type, and means for holding in this plane also known and not shown. , formed for example of lateral bearing surfaces. The portion 2B pivots in a bearing block 54 movable in this me plane of the shafts 2 and 3.

 In an alternative embodiment not shown, a one-piece shaft 2 is supported at its narrow end of the drive roller 31 by a spherical bearing allowing the angular movement, a ball which then replaces the bearing 52.

 The second driven shaft 3 is fixed like the shaft 4. These bearings have not been shown for the sake of clarity in FIG. 5.

 The drive roller 31 is pressed towards the drive roller.

32 by means of a pressing device 55 acting on the bearing block 54.

This device comprises an elastic means 56, such as a spring, the pressure of which is adjustable by means of a screw 57, rotating in a fixed nut-body 57A; the role of this screw is comparable to that of screw 22 of the
Figure 1.

 This pressing device allows the rollers to absorb the differences in wire diameter, stops, not shown, being provided to prevent any contact between the drive rollers 31 and 32.

 In this close-up or “engaged” configuration, rollers 31 and 32, in which a minimum space is provided between the latter, the thread is supported by friction with grooves 33 and 34 which are provided with the edges of said rollers 31 and 32 respectively. These grooves, like the grooves 13 and 14 in FIG. 1, have radii substantially equal to that of the wire to be supported.

 The "disengaging" of this discontinuous wire drive device 1 is provided by a disengaging lever 60 which revolves around a fixed pivot 61, linked to an element of the frame 51 ', parallel to the shafts 2, 3 and 4. This lever 60 comprises a leading arm 62 interposed between the rotation shafts 2 and 3 and an operating arm 63 placed under the control of a ca-me 65 secured to the driving shaft 4. This cam cooperates with a roller 64 secured said operating arm 63.

 The driving arm 62 of the lever 60 acts on the shaft 2 by the intermediary of a driving roller 66, in the direction of the spacing of said shaft 2 with respect to the shaft 3, against the pressing device 55. The latter tends to bring the shaft 2 towards the shaft 3 as soon as the drive roller 66 secured to the shaft 2 is no longer stressed.

 In the separated or disengaged configuration of the entrainment rollers 31 and 32, the wire is no longer pressed and therefore no longer driven.

Cam 65 is formed by a circular disc whose radius is reduced over a predetermined angular sector.
According to a variant shown in Figure 6, a cam 165 present tme reduction of radius on an adjustable angular sector) it consists of two contiguous circular discs, similar to the cam 65, but angularly adjustable one relative to the other.

 When the cam 65 cooperates with the roller 64 by its sector r of reduced radius, the arm 62 of the lever exerts no spacing force on the roller 66, and the wire is supported by the rollers 31 and 32.

 When the cam 65 cooperates with the roller 64 by its sector of maximum radius, said roller 64 is pushed back down, which causes the arm 63 to rise, which spreads the two rollers 31 and 32. The wire is no longer driven, the the space between rollers being maximum, and the rollers no longer exerting any clamping force on the wire 1.

 Advantageously fixed at the free end 63A of the maneuvering arm 63 of the disengaging lever 60 is a pressing device 70 adapted to brake and immobilize the wire against a fixed base 71. Such a braking device possibly contributes to preventing any lateral escape of the wire. , and participates if necessary, in its longitudinal positioning. The device 70 is of the same nature as the device 55 with a spring 72, the pressure on the wire is adjustable by means of a screw 73. The nut body associated with the latter is here the operating arm 63 of the lever.

The length L of wire supported between two stops is written
L = kjre k NR
not
- If k is a coefficient representative of the pressure between rollers and the friction existing between rollers and wire
-rest the aforementioned cam sector of reduced radius
- N and n are numbers of teeth of the pinions 41 and 42 respectively;
- And R is the radius at the bottom of the groove of the drive rollers 31 and 32.

 I1 thus appears that this drive length L is all the more important that the wheel 41 has a high number of teeth N relative to that n of the teeth of the pinion 42, and that therefore the pair of pinions 41-42 constitutes a strongly speed multiplier device.

 It can be seen that, at a given drive length L, the device in FIG. 5 allows the use of rollers 31 and 32 much smaller than the rollers 11 and 12 of FIG. 1, and therefore less bulky, without introducing for as many excessive sprockets or cams. The value can approach as close as you want to 360, if necessary.

Unlike the device of the Figures, it is not necessary here to change the rollers when one wants to vary the quantity L for a given wire size without necessarily changing the pinions 41 and 42 it suffices to implement a cam 165 which can be adjusted as required. The spacing between rollers 31 and 32 can be justified on a small range depending on the size of the wire to support
To facilitate the synchronization of the operations to be carried out during immobilizations or advances of the wire with the latter, cams controlling these operations are advantageously mounted on the driving shaft 4 which carries the cam 65 for disengaging control of the wire drive device .So for example, in the case of a transformation of the wire 1 into a spring, there is mounted on the shaft 4 a cam 80 for controlling and adjusting the conicity of the springs, a cam 81 for controlling a shear, not shown, for cutting the wire, and a cam 82 for controlling and adjusting the pitch of the springs, these cams controlling the corresponding tools by an appropriate linkage. These known tools, as well as the devices which drive them, which are not part of the invention, are not described here.

 The two discontinuous wire drive devices, illustrated in FIGS. 1 and 5, have been described previously only by way of preferred example. It goes without saying that many variants and equivalents can be proposed by those skilled in the art without departing from the scope of the invention.

 Thus the section of the wire is in fact arbitrary, the shape of the grooves, if there are grooves, being modified accordingly. I1 can be for example strips with rectangular section.

 The invention has been described in connection with metal wire for a spring. It is understood that the wire is of any material, and that its entrainment can ensure the supply of wire to wire processing machines, or serve for the transport of elements, fixed to the wire directly or indirectly, as appropriate to present successively in various successive treatment stations, the wire then forming a loop.

 It should also be noted that the essential idea of the invention is to vary the space between two rollers, in any way, between a minimum value for which the wire is driven by friction and a maximum value for which the entry effort is zero. The shape of the recesses shown in Figure 1 is arbitrary. As for the action on the driven shaft 2, it can be done, as desired, in the direction of disengagement or engagement, the disengaging cam 65 acting di rectetnent or not on the movable shaft. The shaft 3 can also be made mobile. The mobility of these shafts at the level of the drive rollers can correspond to an angular or translational movement. In addition, any of the trees 2, 3 and 4 can be made a leading tree.

The diameter of the drive rollers can be different within the same pair if a non-straight wire drive is desired. The rollers can also be cylindrical or conical depending on the shape of the volume available. Any number of recesses or reductions in diameter on the rollers 11, 12 or on the cam 65 can be provided, regularly distributed or not. Several pairs of rollers can be used side by side.

 The control cam 65 (or 165) can be replaced by any other device, electronic or not, adapted to ensure precise control of the movement of the movable shaft 2.

Claims (18)

Rj-AIN  1. Discontinuous wire drive device; in which a wire is interposed between the edges of at least a pair of two drive rollers rotating in opposite directions, characterized in that said drive rollers (11, 12, 31, 32), driven in rotation so continuous, are adapted to provide between their edges a variable space, sometimes minimum, sometimes maximum, so as to apply to the wire (1) respectively, a friction training force sometimes positive, sometimes zero.  2. Device according to claim 1, characterized in that the entrainment rollers (11, 12) of each pair are circular disks, one of which (11, 12) at least has on its edge at least one circumferential recess (15, 15 ') of predetermined angular amplitude (X).  3. Device according to claim 2, characterized in that on the edge of each drive roller (11, 12) is formed a groove (13, 14) for guiding and tightening the wire (1) to be driven, said circumferential recess (15) corresponding to a significant increase in the size of the throat.  4. Device according to claim 2, characterized in that on the edge of each roller (11, 12) of drive is formed a groove (13, 14) for guiding and tightening the wire (1) to help each other, said circumferential recess (15 ') corresponding to a reduction in the radius of the roller substantially greater than the size of the groove, thus causing local disappearance of the groove.  5. Device according to any one of claims 2 to 4, characterized in that on the edges of the two drive rollers (11, 12) are formed a plurality of circumferential recesses (15, 15 ') regularly distributed, arranged so as to come alternately opposite the wire (1) to help each other.  6. Device according to claim 1, characterized in that the drive rollers of each pair are two cylindrical discs (31, 32) of the same diameter of which the first, mobile (31) is adapted to move away from the second, fixed (32) the rotation shaft (2) obstructing said movable disc admitting at the latter a transverse clearance.  7. Device according to claim 6, characterized in that the movable disc (31) is controlled by a cam (65, 165) cooperating with a roller (64X whose rotation is continuous.  8. Device according to claim 7, characterized in that said roller (64) is carried by a lever (60) which revolves around a fixed pivot (61) parallel to the rotation shaft (2) of the movable disc ( 31) and one arm (62) of which acts on a release roller (66) carried by said rotation shaft.  9. Device according to claim 8, characterized in that said lever arm (60) acts in the direction of the spacing of the movable disc (31) with respect to the fixed disc (32) against a pressing device (55) tending to bring the two discs towards each other.  10. Device according to claim 9, characterized in that the lever (60) comprises a second arm (63) carrying the roller (64) cooperating with said cam (65), of which is secured a braking device (70) adapted to act on the wire (1) to be driven when the discs are spaced.  11. Device according to any one of claims 7 to 10, characterized in that the cam (65, 165) is integral with a driving shaft (4) which overhangs the rotation shaft (2) of the movable disc (31 ) by means of a first pair of two toothed pinions (41, 42) integral with these shafts (2, 4), said rotation shaft (2) of the movable disc (31) by cutting the rotation shaft ( 3) of the fixed disc (32) by means of a second pair of toothed pinions (43, 44) integral with these shafts (2, 3).  12. Device according to any one of claims 7 to 11, characterized in that the cam (65) is formed of a circular disc whose radius is reduced over a predetermined angular sector (r).  13. Device according to any one of claims 7 to 11, characterized in that the cam (165) consists of two adjoining circular discs, identical, the radius of which is reduced over a predetermined angular sector (<), these discs being adjustable angularly with respect to each other.  14. Device according to any one of claims- 6 to 13, characterized in that the rotation shaft (2) of the movable disc (31) is supported, at a distance from said movable disc by a spherical bearing (53) allowing an angular movement of said shaft.  15. Device according to claim 11, characterized in that it supplies wire to a wire transformation machine performing cutting and processing operations for said wire, at least one of these operations being controlled by a cam (80, 81, 82) carried by the driving shaft (4).  16. Device according to any one of claims 6 to 15 for driving a circular wire, characterized in that on at least one of the drive rollers is formed a circumferential groove of radius substantially equal to that of the wire to be driven .  17. Device according to any one of claims 1 to 16, characterized in that the minimum space between the drive rollers is adjustable according to the size of the wire to be driven, stops being provided to prevent any contact between the drive rollers.  18. Device according to any one of claims 1 to 14, 16 and 17, characterized in that the wire to be supported (1) forms a loop to which are fixed different elements intended to describe a circuit in a discontinuous manner.