EP0473739A1

EP0473739A1 - Device for straightening a wire.

Info

Publication number: EP0473739A1
Application number: EP91905046A
Authority: EP
Inventors: Pierre-Louis Piguet; Peter Meier
Original assignee: Esco SA
Current assignee: Esco SA
Priority date: 1990-03-26
Filing date: 1991-03-21
Publication date: 1992-03-11
Anticipated expiration: 2011-03-21
Also published as: WO1991014522A1; EP0473739B1; JPH04506771A; FR2659879B1; US5161399A; FR2659879A1

Abstract

L'invention concerne un dispositif de dressage d'un fil métallique rigide (3) livré sous forme enroulée et alimentant une machine d'usinage (7). Le dispositif est agencé de façon à être peu encombrant et facile à régler. Le fil (3) est stationnaire dans un conduit axial d'un rotor porté par un chariot (6) mobile axialement (B) au moyen d'un premier vérin hydraulique (13). Le rotor porte le fil (3) par des guides stationnaires et un guide central qui est déplacé radialement (C) entre une position centrée et une position excentrique au moyen d'un second vérin hydraulique (62) pendant la rotation du rotor et l'avance du chariot (6). Le fluide hydraulique recueilli à la sortie (71) du premier vérin est transmis directement à une entrée (66 ou 67) du second vérin (62) de façon à l'actionner à une vitesse proportionnelle à celle du premier.The invention relates to a device for straightening a rigid metal wire (3) delivered in coiled form and feeding a machining machine (7). The device is arranged so as to be compact and easy to adjust. The wire (3) is stationary in an axial duct of a rotor carried by a carriage (6) movable axially (B) by means of a first hydraulic cylinder (13). The rotor carries the wire (3) by stationary guides and a central guide which is moved radially (C) between a centered position and an eccentric position by means of a second hydraulic cylinder (62) during the rotation of the rotor and the advance of the carriage (6). The hydraulic fluid collected at the outlet (71) of the first jack is transmitted directly to an inlet (66 or 67) of the second jack (62) so as to actuate it at a speed proportional to that of the first.

Description

DEVICE FOR DRESSING A METAL WIRE

The present invention relates to a device for straightening a rigid metal wire, in particular at the entrance to a machining machine, comprising a frame on which are mounted means for holding this wire, a rotor coupled to means of drive in continuous rotation, this rotor being provided with an axial duct traversed longitudinally by the wire, a reciprocating drive means arranged to produce a relative longitudinal movement between the rotor and the wire, a guide movable central through which the wire and mounted in the rotor so as to be moved transversely relative to the axial duct, between a substantially centered position and an eccentric position, eccentricity control means arranged to move the central guide by means of fluid pressure during rotation of the rotor, and stationary guides traversed by the wire and arranged in the axial duct on either side of the central guide.

In machines intended for the manufacture of small parts by machining, in particular by turning, the material is often supplied in the form of a wire delivered in a ring from which it is unwound to penetrate longitudinally into the machine. However, a preliminary straightening of the wire is necessary to ensure the straightness of the finished part. In general, it is carried out by a dressing device installed at the entrance to the machine and operating intermittently, after each advance of the wire, for the manufacture of a new part. It should be noted that the term "wire" used here can designate a metallic element with a circular profile or not and relatively rigid, its transverse dimensions generally being of the order of several millimeters and possibly ranging up to approximately 10 to 12 mm.

The invention relates to a rotary type rectifier, in which the wire is arranged substantially along the axis of a rotor generally containing five guides, namely a central guide movable transversely so as to deform the wire and two pairs of stationary guides supporting the wire on either side of the central guide. Dressing is obtained in a known manner by a combination of the eccentra tion of the central guide, the rotation and the relative displacement of the rotor relative to the wire or vice versa. These movements cause a helical propagation inflection in the wire, which deforms it beyond the elastic limit to an extent appropriate for it to return elastically to a rectilinear shape. Of course, the amplitude of the eccentricity and the distance between the guides must be adapted to the dimensions and the mechanical characteristics of the different wires to be treated.

The known devices applying this technique have a certain number of drawbacks from the point of view of construction and operation. The need to offset the central guide in a progressive manner during the movement of the rotor relative to the wire requires complicated mechanisms which are generally controlled by cams actuated by a camshaft from the machine tool. Therefore, the size of the device is relatively large and in particular the rotor is much longer than the distance occupied by the guides, because of the space required for the control mechanism between the two bearings of the rotor. In addition, this mechanism is relatively complicated, with a large number of references, levers etc. , resulting in a relatively high cost, balancing difficulties and games altering the operating precision. Furthermore, current constructions require precise adjustment of the stationary guides and this adjustment can only be made when stationary, hence a fairly long adjustment time.

Patent application FR-A-2 312 314 (= DE-A-2 523 831) describes a stationary straightening device which the straightening wire crosses continuously and where the eccentricity of the central guide is controlled by an axially sliding bush. on the rotor, this bushing having axially inclined surfaces against which a support for the central guide rests. This support slides radially when the socket is moved radially by means of a control mechanism. DE-A-2 707 970 describes an improvement of this device, where said control mechanism is actuated by a pneumatic cylinder, while the rotor rotates, in particular to return the guide to the centered position if the advance of the wire stops for some reason. However, this pneumatic control is not intended to perform operating cycles with progressive displacement of the central guide. Besides, the device is intended to work continuously and not in cycles.

The object of the present invention is to provide a device making it possible to substantially avoid the drawbacks mentioned above, thanks to a simple and compact construction, making it possible to control the central guide in an easy and precise manner.

To this end, the invention provides a device of the type indicated in the preamble, characterized in that the reciprocating drive means comprises a first hydraulic cylinder, and in that the eccentricity control means comprise a second hydraulic cylinder which is hydraulically coupled to the first cylinder so as to operate at a speed dependent on that of the first cylinder.

In a preferred embodiment, the rotor is mounted by bearings on a carriage movable on the frame in the longitudinal direction of the wire and coupled to the first cylinder.

When, the central guide of the device comprises a support sliding radially in the rotor and provided with a support member at its end furthest from the axis of the rotor, and when the eccentricity control means comprise a sliding bush , mounted on the periphery of the rotor so as to rotate with it and provided with an axially inclined bearing surface, against which said bearing member is applied, said inclined bearing surface may be formed by a removable element fixed to the sliding sleeve and covering a radial bore in which the support is mounted sliding from the central guide. Preferably, said support member of the sliding support comprises a roller rolling on the inclined support surface, and the opposite end of said support is supported on a spring tending to keep the roller applied against said surface.

In a preferred embodiment, the eccentricity control means comprise a rotary sliding block, mounted around the sliding bushing by means of at least one bearing, this block being coupled to the second cylinder and cooperating with stops defining said positions of the central guide.

On each side of the central guide, the rotor may have an axial bore in which a tubular sleeve containing at least two stationary guides can be removably mounted, from a corresponding end of the rotor. Preferably, each guide has a guide barrel mounted inside a bearing, each of the tubular sleeves has a cylindrical axial bore, and the bearings of the stationary guides are inserted into said bore of the sleeve and are held axially in positions. respective selected by means of interchangeable tubular spacers.

In an advantageous form of the invention, the hydraulic cylinders are double-acting and said second cylinder, controlling the central guide, comprises two opposite chambers which are connected alternately, thanks to an electrically controlled reversing valve, an outlet from the first cylinder and a fluid return line, so that the speeds of the two cylinders are proportional to each other. Said outlet of the first jack can be connected to a return line through a spring valve allowing said fluid flow to pass when the stroke of the second jack is blocked by a stop. Preferably, the device comprises means for measuring the speed of the rotor and for adjusting the flow of fluid actuating the first cylinder as a function of the speed of the rotor. The present invention will be better understood with the aid of the following description of a preferred embodiment, with reference to the appended drawings, in which:

fig. 1 is a schematic side view of an installation comprising a dressing device according to the invention, associated with a machine for machining the wire drawn by this device,

fig. 2 is a view from the rear of the carriage of the dres¬ sage device, in the direction of advance of the wire,

fig. 3 is an axial sectional view along line III-III of FIG. 2, and

fig. 4 schematically represents the hydraulic circuit of the device.

With reference to fig. 1, a common frame 1 carries an unwinder 2 for a rigid metal wire 3 wound on a reel 4, a device 5 for straightening the wire according to the invention, equipped with a carriage 6 movable back and forth along the wire, and a machining machine 7 such as a turning machine, machining successive sections of wire 3 and equipped with a device 8 for intermittently holding and advancing wire 3 in the direction of arrow A. The straightening device 5 straightens a determined length of the wire 3 while the latter is kept stopped by the device 8 „for example immediately after an advance operation. The dressing takes place during a movement of the carriage 6 in the direction of the arrow B.

Figs. 2 and 3 show the main part of the dressing device 5, namely that which is carried by the carriage 6. However, in order to clarify the drawing, certain elements such as the electrical or hydraulic connections are not shown in detail. The carriage 6 has a chassis 10 fitted with sliding bearings 11 in order to be able to move back and forth on slides 12 fixed to the frame 1, by means of a double-acting forward hydraulic actuator 13 a stud 14 fixed to the chassis 10. This chassis carries a rotor 15 of axis 16, by means of two bearings 17, and an electric motor 18 driving in continuous rotation the rotor 15 by means of a pulley transmission 19, 20 and toothed belt 21. The pulley 20 is fixed to the rotor 15 by means of a key and a screwed ring 22 provided with notches cooperating with a detector 23 to provide a signal representative of the speed of rotation of the rotor 15.

As seen in fig. 3, the rotor 15 surrounds an axial duct 24 in which the wire 3 (not shown in this figure) is guided along the axis 16 by means of four stationary guides 25 and a central guide 26 movable transversely. In practice, these different guides must be spaced from each other to an extent corresponding approximately to ten times the diameter of the wire. The stationary guides 25 are mounted in pairs in a rear sleeve 28 and a front sleeve 29 which are easily removable, since they are inserted into an axial bore of the rotor and screwed into the latter by means of threads 30, 31 and abutment shoulders 32, 33. Each sleeve 28, 29 is provided with a cylindrical axial bore in which the guides 25 are wedged by means of tubular spacers 34 to 36 between a stop ring 37 and a nut 38 open at its center. Each guide 25 comprises a guide barrel 40 provided with an orifice suitable for the section of the wire. This barrel is mounted in the inner ring of a bearing 41, the outer ring of which is adjusted in the corresponding sleeve 28, 29 and clamped between the in ± spacers.

Thus, any change in the position or type of stationary guides 25 in the dressing device can be done very quickly, since it suffices to unscrew the sleeves 28 and 29 and replace them with two other sleeves fitted with prior to appropriate guides. In this way, all the positioning and centering operations of the stationary guides can be done outside the rotor. The movable guide 26 also includes a straightening barrel 42 traversed by the wire and a bearing 43 fixed in a support 44 which is slidably mounted in a radial bore 45 of the rotor, where it is guided by means of a pin 46 and a groove 47. The support 44 is pushed, in the direction of a centered position of the guide 26, by a spring 48 pressed against a cover 49. This spring plays a role essentially when stationary, because during the rotation of the rotor the support 44 is biased in the same direction by the centrifugal force. On the side opposite to the spring, the support 44 is equipped with a roller 50 pressing against an axially inclined surface 51, forming a movable ramp whose axial movements control the radial movements of the central guide 26, between a centered position and a position adjustable offset.

A rotary cylindrical sleeve 52 provided with a collar 53 is slidably mounted axially on the cylindrical external surface of the rotor 15, where it is guided by a key not shown. The collar 53 is interrupted opposite the radial bore 45 of the rotor, to allow the entry and exit of the central guide 26 and its support 44, as well as for the mounting of a wedge-shaped part 54 provided with the inclined surface 51. This part is fixed to the collar 53 by two lateral screws 55 allowing it to be easily removed to change the guide 26. A sliding block 56 surrounds the rotary sleeve 52, on which it is mounted by means of a bearing 57 allowing it to exert an axial thrust on the sleeve without turning with it. This block 56 is provided with a lower protrusion 58 in which is fixed a guide pin 59 mounted in a longitudinal slide 60 inside the carriage. One end of the axis 59 is integral with the piston 61 of a double-acting hydraulic cylinder 62 called a diving cylinder, because it controls the eccentric movement of the central guide 26. One end 63 of the body of the cylinder 62 forms a stop for the axis 59, this stop defining the centered position of the guide 26. The other end of the axis 59 cooperates with an adjustable stop formed by a screw 64 next to which the carriage carries a graduated rule 65. This allows d '' easily adjust the maximum eccentricity of the central guide 26, without a stop being necessary on the rotor. The fact that the stops 63 and 64 act directly at the level of the diving cylinder 62 has the advantage of avoiding any transmission of stop forces and of sparing the mechanical elements installed on the rotor. In addition, the stop 64 can be adjusted while the rotor is rotating. In FIGS. 2 and 3, a distinction is also made between the inlet and outlet fittings 66, 67 of the diving cylinder 62, for the connection of flexible hydraulic lines due to the stroke of the carriage 6, which is generally of the order 100 mm.

If the inclined surface 51 is planar or conical with an axis 16, the radial displacement of the central guide 26 is linear with respect to the stroke of the diving cylinder 62. The ratio between these two displacements is defined by the inclination of the surface 51, which allows great precision in the control and adjustment of the extreme positions of the guide.

In general, the rotor 15 rotates continuously and at a constant speed during the operations of machining, advancing and straightening the wire. The dressing takes place during the forward movement of the carriage 6 in the direction of the arrow B. During this time, the diving cylinder 62 is actuated so as to move gradually to the left, from the rest position of FIG. 3, the coulis¬ block 56 and the rotating sleeve 52, for lowering the central guide 26 to its eccentric position defined by the stop 64. The assembly remains for a few moments in this position and then the actuator 62 is actuated in the another direction so as to gradually return the central guide 26 to the centered position before the end of the carriage stroke. To avoid breaking the wire and to obtain a suitable dressing, it is important that the plunging movement of the central guide 26 is progressive and synchronized with its axial movement relative to the wire, that is to say with the movement of the carriage. under the effect of the advance cylinder 13. This problem is solved in a simple manner by means of the hydraulic control. The diagram in fig. 4 shows how the advance cylinder 13 and the diving cylinder 62 are hydraulically coupled so as to operate at synchronous speeds during a wire straightening cycle. The advance cylinder 13, ensuring the axial movement of the carriage 6, has inlet and outlet connections 70 and 71 which are connected to a pipe 72 for supplying pressurized fluid and to a pipe 73 for returning the fluid , through a solenoid valve 74, a flow limiter 75 and, on the side of the connection 71 of the cylinder 13, two spring valves 76 and 77 mounted in opposition and calibrated at a pressure corresponding to about half the pressure of supply in line 72.

The inlet and outlet connections 66 and 67 of the diving cylinder 62 are connected, through a solenoid valve 78, on the one hand to a return pipe 79 and on the other hand to the connector 71 of the cylinder 13 through a valve 80 controlled by the respective pressures prevailing on either side of the valves 76 and 77. During normal operation of the device, this valve does not play a role and remains in the position shown.

The hydraulic diagram shows the different organs in the rest position, before a wire straightening cycle. In the regulator 75, a throttle 81 connected to the inlet 70 of the jack is adjusted as a function of the speed of the rotor in order to adjust the speed of movement of the jacks, while the other throttle 82 is open to 100%. The cylinders 13 and 62 are in abutment (on the left in the diagram in fig. 4). To start the wire straightening cycle and produce the movement of the carriage 6 in direction B, the solenoid valve 74 is activated, so that pressurized fluid enters the jack 13 through the connector 70 and that fluid exits through the fitting 71. After activation of the solenoid valve 78, this outgoing fluid is transmitted to the inlet 66 of the diving cylinder 62 and therefore actuates the latter in the direction of arrow C at a speed proportional to that of the cylinder 13, that is to say that the central guide is offset linearly with respect to the movement of the carriage 6. When the diving cylinder 62 arrives in abutment (abutment 64, fig. 3) the fluid leaving the jack 13 returns through the valve 76.

Before the carriage has completed its travel, the central guide is returned to its centered position by deactivating the valve 78, so that the fluid leaving the connection 71 of the cylinder 13 enters the connection 67 of the cylinder 62 and actuates the latter. ci in the opposite direction to C, always at a speed proportional to that of the jack 13. Then, to return the carriage to its starting position, the valve 74 is deactivated so that it returns to the position shown in the figure and the pressurized fluid is transmitted to the connection 71 of the cylinder 13. The cylinder 62 having already arrived in abutment, it no longer moves and the central guide 26 remains in the centered position. The throttle 82 allows the return speed of the carriage 6 to be adjusted.

During manual adjustments of the dressing parameters, the carriage and the advance cylinder 13 are at rest, so that the valve 78 is directly supplied with pressure at its inlet 84. It is therefore possible to command the guide diving central as if the two cylinders 13 and 62 were decoupled. However, the diving speed should not be too high, as the wire would be badly drawn. This is why there is provided the valve 80 which is activated by the pressure at the outlet of the throttle 82, so as to reduce the flow rate of the fluid. In normal operation, the valve is deactivated by the pressure discharged through the connection 71 of the cylinder 13.

The effort required to offset the central guide varies greatly depending on the nature and dimensions of the material to be dressed. On the other hand, the choice of the opening pressure ^ Pl of the non-return valve 76 must make it possible to draw up the most resistant material.

It follows that, when dressing small material, the pressure difference required between points 84 and 73 to actuate the diving cylinder 62 would be much lower than the value set on the valve 76. Therefore, when the cylinder 62 will come to a stop, the pressure at fitting 71 will suddenly increase up to a level allowing the opening of the valve 76, which will cause a jerk. This is avoided by the use of a pressure difference regulator 85 which makes it possible to adjust the pressure difference ΔP2 between points 73 and 84 to a value close but always less than the value ^. 1 set on valve 76. The pressure at 71 is therefore kept almost constant whatever the resistance offered by the material during dressing. This therefore allows the device to work on a wide range of materials and dimensions.

The foregoing description shows that the invention makes it possible to produce a dressing device having a relatively simple construction and a reduced bulk, thanks to the judicious arrangement of the elements. In addition, the hydraulic control is very simple and allows without difficulty to synchronize the movements of advance and diving of the central guide in order to ensure an optimal dressing of the wire. Finally, the preparation and adjustment operations of the device for straightening a given type of wire are very simplified compared to known devices, thanks to the elimination of manual centering of the material and the possibility of preparing the stationary guides outside the machine. .

The present invention is not limited to the embodiment described above, but it extends to any modification or variant obvious to a person skilled in the art. In particular, the same principles of construction and operation are applicable to a device where it is the wire which moves longitudinally during the dressing operation, thanks to a hydraulic cylinder replacing the cylinder 13, while the rotor remains in place. .

Claims

1. Device for straightening a rigid metal wire, in particular a wire at the entrance to a machining machine, comprising:

- a frame (1) on which are mounted means (8) for holding this wire,

- a rotor (15) coupled to means for driving in continuous rotation, this rotor being provided with an axial duct (24) traversed longitudinally by the wire,

- a reciprocating drive means arranged to produce a relative longitudinal movement between the rotor (15) and the wire (3),

- a movable central guide (26) traversed by the wire and mounted in the rotor so as to be displaced transversely relative to the axial duct, between a substantially centered position and an eccentric position,

- eccentricity control means ^* arranged to move the central guide (26) by means of a fluid pressure during the rotation of the rotor, and

- stationary guides (25) traversed by the wire and arranged in the axial duct on either side of the central guide, characterized in that the reciprocating drive means com¬ carries a first hydraulic cylinder ( 13), and in that the eccentricity control means comprise a second hydraulic cylinder (62) which is hydraulically coupled to the first cylinder (13) so as to operate at a speed dependent on that of the first cylinder.

2. Device according to claim 1, characterized in that the rotor (15) is mounted by bearings (17) on a carriage (6) movable on the frame in the longitudinal direction of the wire (3) and coupled to the first cylinder ( 13).

3. Device according to claim 1, wherein the central guide (26) comprises a support (44) sliding radially in the rotor and provided with a support member (50) at its end furthest from the axis ( 16) of the rotor, and in which the eccentricity control means comprise a sliding bush (52), mounted on the periphery of the rotor so as to rotate with it and provided with an axially inclined bearing surface (51), against which said bearing member is applied, characterized in that said inclined bearing surface (51) is formed by a removable element (54) fixed to the sliding bushing (12) and covering a radial bore (45) in which the sliding support (44) of the central guide is mounted.

4. Device according to claim 3, characterized in that said support member of the sliding support (44) comprises a roller (50) rolling on the inclined support surface, and in that the opposite end of said support (44 ) is supported on a spring (48) tending to keep the roller applied against said surface (51).

5. Device according to claim 3, characterized in that the eccentricity control means comprise a rotary sliding block (56), mounted around the sliding bushing by means of at least one bearing (57), this block being coupled to the second cylinder (62) and cooperating with stops (63, 64) defining said positions of the central guide.

6. Device according to claim 1, characterized in that, on each side of the central guide (26), the rotor (15) has an axial bore in which a tubular sleeve (28, 29) containing at least two stationary guides (25 ) is removably mounted from a corresponding end of the rotor.

7. Device according to claim 6, characterized in that each guide (25, 26) comprises a guide barrel (40, 42) mounted inside a bearing (41, 43), in that each of the sleeves tubular (28, 29) has a cylindrical axial bore, and in that the bearings (41) of the stationary guides are inserted in said sleeve bore and are held axially in respective positions selected by means of interchangeable tubular spacers (34, 35, 36).

8. Device according to claim 1, characterized in that the hydraulic cylinders (13, 62) are double acting and in that said second cylinder (62), controlling the central guide, has two opposite chambers which are connected alternately, thanks to an electrically controlled reversing valve (78), to an outlet (71) of the first cylinder (13) and to a line (79) of the fluid return, so that the speeds of the two cylinders are proportional one to the other.

9. Device according to claim 8, characterized in that said outlet (71) of the first cylinder is connected to a return line (73) through a spring valve (76) allowing said fluid flow when the stroke of the second cylinder (62) is blocked by a stop (64).

10. Device according to claim 8, characterized in that it com¬ carries means (23, 81) for measuring the speed of the rotor (15) and for adjusting the flow of fluid actuating the first cylinder (13) as a function of rotor speed.