Drawbench

Description

Field of application

[0001] The present invention, in its most general aspect, refers to a drawbench for a metal wire according to claim 1, a device for rearming a drawbench according to claim 15 and a method for operating a drawbench according to claim 16, for a production line for screws, bolts and similar small metal articles, from a wire and that essentially comprises, in succession, a reel, on which said wire is wound, a drawbench and utilizing machine of the drawn wire, for example a bolt moulding machine, an example of which is known from GB-A-1 169 231.

[0002] In particular, the present invention refers to a production line for small metal articles of the aforementioned type, in which the wire, unwound from the respective reel, is made to advance through the drawbench, pulled step by step by the utilizing machine of the drawn wire.

[0003] Even more specifically this invention concerns a drawbench for wire, which can be used for production lines for small metal articles of the aforementioned type, said wire unwinding from a reel and being pulled step by step by utilizing machine of the drawn wire, said drawbench being of the type comprising a drawing die guided in a mobile manner on a frame, a device for moving said die along a drawing stroke and means for rearming said device.

Prior Art

[0004] It is known that for the production, for example, of bolts, screws and other similar small metal articles starting from metal wires, it is necessary for the predetermined wire to be calibrated and/or hardened on the surface in an appropriate manner, before proceeding to the actual forming of said articles like, for example, cutting into pieces of predetermined length, obtaining cylindrical, polygonal and similar heads, mechanical chip removal operations like turning, milling, threading and the like.

[0005] And it is known that, for such a purpose, the technology of subjecting the wire to drawing is advantageously applied.

[0006] In production lines of bolts, screws or other similar small metal articles starting from wires, drawbenches and in particular so-called mobile die drawbenches are consequently widely used, where the wire to be drawn is made to advance step by in step and the drawing of subsequent portions of wire is carried out by moving the drawing die on the wire held still.

[0007] In accordance with the aforementioned technology, the advance step by step of the wire is advantageously carried out by the same utilizing machine of the drawn wire, arranged downstream and in line with the mobile die drawbench.

[0008] In such a known drawbench it is therefore possible to identify a mobile die for drawing, guided in a mobile manner on a frame, a device for moving said die along a drawing stroke and rearming means of said device for a subsequent drawing stroke of the die. In general, in the prior art, taking into account that the die is constantly engaged on the wire to be drawn, the return of said die at the start of the drawing stroke takes place "automatically" each time the wire is pulled by the utilizing machine; consequently, in accordance with the prior art, in mobile die drawbenches, specific means for carrying out the aforementioned return of the die at the start of the drawing stroke are not provided.

[0009] In said machines, on the other hand, the device for moving the die comprises a cylinder-piston group with double action. The piston of the aforementioned group, starting from a starting condition, is commanded alternately to make the mobile die perform the drawing stroke and to return to said starting condition, respectively.

[0010] Although advantageous from various points of view, the known drawbench schematically described above has recognised drawbacks.

[0011] The most noticeable drawback is that the productivity of the drawbench is limited by the time used in the return stroke of the piston, a time that is relatively long.

[0012] The cylinder, indeed, having to be sized to provide the die with all of the energy necessary for the drawing operation, for a sufficient time to perform the entire drawing stroke, generally occupies considerable volumes. In order to fill such volumes with a fluid, relatively long times are required and this occurs both for the drawing stroke and for the return stroke, that is equal and opposite.

Summary of the invention

[0013] The technical problem underlying the present invention is that of devising and providing a mobile die drawbench of the type considered above, having structural and functional characteristics able to overcome, in a simple and cost-effective manner, the aforementioned drawbacks mentioned with reference to the prior art.

[0014] The technical solution idea of said problem is that of deactivating said device at the end of each drawing stroke and carrying out the rearming thereof interlocking it with the drawing die during the return thereof at the start of the drawing stroke.

[0015] Based upon this solution idea, the problem outlined above is solved, according to the present claims 1, 15 and 16.

[0016] Further characteristics and advantages of the drawbench according to the present invention shall become clearer from the following description of a preferred embodiment thereof, provided for indicating and not limiting purposes with reference to the attached drawings.

Brief description of the drawings

[0017] 

Figure 1 schematically represents a side view of a production line of screws, bolts and similar small metal articles, comprising a drawbench of a wire according to the present invention.

Figure 2 schematically represents an enlarged side view of a detail of the line of figure 1, and specifically of the drawbench according to the invention.

Figure 3 schematically represents a side view of the drawbench of figure 2, in a different operating position.

Figure 4 schematically represents a side view of another embodiment of a drawbench of wire, according to the present invention.

Figure 5 schematically represents a side view of the drawbench of figure 4, in a different operating position.

Detailed description of a preferred embodiment

[0018] With initial reference to figure 1, a production line of screws, bolts and similar small metal articles, globally indicated with 10, comprising a drawbench 11, in accordance with the present invention, of a wire 13, is shown. The wire 13 is unwound from a reel 14 and is pulled step by step by utilizing machine 15 of drawn wire.

[0019] The drawbench 11, which is shown enlarged in figures 2 and 3, is of the type comprising a drawing die 17 guided in a mobile manner on a frame 16, a device 18 for moving said die 17 along a drawing stroke and rearming means 19 of said device 18.

[0020] In accordance with an aspect of the present invention, said rearming means 19 of said device 18 comprise the die 17.

[0021] More specifically, the device 18 comprises a lever 20 of the first type and a cylinder 22 and piston 24 group 21, the cylinder 21 being arranged in a predetermined position of the frame 16.

[0022] The lever 20 is pivoted in the frame 16 and has an end 20a subjected to the action of the cylinder 22 and piston 24 group 21 and an opposite end 20b acting on the die 17 to move it along the wire 13 in the drawing stroke, away from the utilizing machine 15, along a work axis X-X of the drawbench 11.

[0023] Preferably, the device 18, which is substantially below the work axis X-X of the drawbench 11, also comprises a mechanical transmission 26, which is placed between said group 21 and said lever 20. This mechanical transmission 26 is preferably a movement amplification transmission.

[0024] The transmission 26 comprises an equalizer 28 and a toggle 30.

[0025] The equalizer 28 has a pivot 28a, in a predetermined position of the frame 16, and two opposite arms 28b and 28c. More specifically, the pivot 28a and the ends of the two arms 28b and 28c have a triangular arrangement, the ends of the two arms 28b and 28c being situated substantially above the pivot 28a.

[0026] The equalizer 28 has a first arm 28b with fixed operative length and a second arm 28c with variable operative length. This is made concrete by the fact that the first arm 28b is rotatably connected to the piston 24, whereas the second arm 28c is equipped with a guide 29 for a ball bearing.

[0027] The toggle 30 comprises two members 32 and 36 rotatably connected to each other by a hinge 33.

[0028] The first member 32, substantially triangular in shape, is rotatably connected to the drawbench 11 substantially close to a first vertex thereof 32a, in a predetermined position of the frame 16. The hinge 33 is provided substantially close to a second vertex 32b: close to the third vertex 32c, on the first member 32 a ball bearing 34 is mounted, suitable for sliding along the guide 29 of the equalizer 28. More specifically, the ball bearing 34 is substantially above the vertices 32a and 32b.

[0029] The second member 36, substantially of elongated shape, is rotatably connected, at one of its ends 36a, to said end 20a of the lever 20. At the opposite end 36b of said second member 36, said hinge 33 is provided.

[0030] It should be noted that, in the example of the figures, the cylinder 22 is mounted with the axis incident to the work axis X-X of the drawbench 11. The group 21 is preferably of hydraulic type and is actuated by a hydraulic control unit 38.

[0031] The operation of the drawbench 11 according to the invention is specified hereafter.

[0032] Figure 2 shows the piston 24 at lower end stop. In such a situation, the die 17 is at start of the drawing stroke.

[0033] More specifically, the ball bearing 34, housed in the guide 29 of the equalizer 28, is in the end of the guide 29 of the second arm 28c of the equalizer 28 that is at the side of the pivot 28a. Consequently, the toggle 30 has the two members 32 and 36 arranged substantially bent.

[0034] The hydraulic control unit 38 supplies pressurised oil into the cylinder 22 until the piston 24 reaches the upper end stop position.

[0035] The die 17 thus performs the drawing stroke, until it is at the end of the drawing stroke, shown in figure 3.

[0036] In such a situation, more specifically, the ball bearing 34, that, as stated, is able to slide in the guide 29 of the equalizer 28, ends up in the end of the guide 29 of the second arm 28c of the equalizer 28 that is at the opposite side to the pivot 28a. Consequently, the toggle 30 ends up having the two members 32 and 36 arranged substantially extended.

[0037] The utilizing machine 15 at this point substantially pulls back the portion of wire 13 that has been drawn. Such a supply step of the utilizing machine 15 takes place having short-circuited the chambers of the cylinder 22, or having placed them in communication with atmospheric pressure: in such a way, the return action of the wire 13 by the utilizing machine 15, as well as taking the die 17 back to the start of the drawing stroke, makes the oil flow back from the cylinder 22 to the hydraulic control unit 38. Thus the pulling back of the utilizing machine 15 also carries out the rearming of the device 18.

[0038] With reference to figures 4 and 5, a second embodiment of a drawbench, in accordance with the present invention and globally indicated with 111, of a wire 13 is shown. In said figures, the elements that are structurally and functionally analogous with respect to those of the drawbench 11 are indicated with the same reference numeral and the detailed description of these is not repeated.

[0039] In this embodiment, the drawbench 111 is equipped with a device 118 comprising a mechanical transmission 126 that includes, as well as the equalizer 28 and the toggle 30, also a member 144. The member 144 has two sides 144a and 144b arranged like a wedge and is arranged between the group 21 and the equalizer 28.

[0040] More specifically, the member 144 is fixed to the piston 24. The cylinder 22 is rotatably connected to the drawbench 111 thanks to a pin 146, preferably provided at the base of the cylinder 22.

[0041] The upper side 144a of the member 144 engages with a ball bearing 148, mounted on the first arm 28b of the equalizer 28 (where, in the previous embodiment of the invention, on the other hand, the piston 24 was rotatably connected).

[0042] The opposite lower side 144b of the member 144 is able to slide on an inclined roller table 150, preferably arranged in a converging manner with respect to the work axis X-X.

[0043] The operation of the drawbench 111 is totally similar to the operation of the drawbench 11 and at this point it is sufficient to recall the following.

[0044] Figure 3 shows the piston 24 at the lower end stop. In such a situation, the die 17 is at the start of the drawing stroke.

[0045] The hydraulic control unit 38 supplies pressurised oil into the cylinder 22 until the piston 24 reaches the upper end stop position.

[0046] The die 17 thus performs the drawing stroke, until it is at the end of the drawing stroke, shown in figure 4.

[0047] More specifically, when the piston 24 advances, the ball bearing 148 is moved upwards from the upper side 144a of the member 144, such a member 144 advancing on the inclined roller table 150.

[0048] It should be noted that the present invention also concerns a device for moving a drawing die of a drawbench of a wire, structured in the ways described above, and respectively indicated with 18 and with 118.

[0049] From the previous description it can clearly be seen that the drawbench of a wire, according to the invention, solves the technical problem and achieves numerous advantages the first of which lies in the fact that unusually high productivity is obtained, thanks to the fact that the idle times, linked to the rearming of the device that is used to move the die are avoided, i.e. the idle times are hidden.

[0050] Another advantage of the present invention is that the device for moving the die of the drawbench has excellent adaptability to the different types of drawbench and consequently, separately commercialised, can easily be used for revamping existing drawbenches.

[0051] Moreover, according to the invention, through the association of the equalizer with variable operating length and of the toggle, a substantially constant drawing speed of the die is surprisingly obtained.

[0052] A further big advantage is the fact that the drawbench according to the invention practically does not need to be adjusted according to the different types of produced pieces: indeed, it is the utilizing machine arranged downstream of the drawbench that, thanks to the mechanical transmission in retrograde motion according to the invention, takes the die, and the device for moving the die itself, automatically back in the configuration of the start of processing, for each subsequent drawing stroke of the wire. This means that the device for moving the die is rearmed automatically for the portion necessary for the subsequent drawing stroke, which can be a different length to the previous one according to the piece produced in the utilizing machine: in this way, with the invention the use of mechanical stops according to the prior art, which had to be adjusted by an operator whenever the type of production was varied, is avoided.

[0053] Of course, a man skilled in the art can make numerous modifications and variants to the drawbench described above in order to satisfy specific and contingent requirements, all of which are in any case covered by the scope of protection of the present invention as defined by the following claims.

Claims

1. A drawbench (11, 111) for a metal wire (13) unwinding from a reel (14), the drawbench comprising a frame (16) and a mobile drawing die (17) guided in a mobile manner on said frame (16), a device (18,118) for moving the die adapted to move said die (17) along a drawing stroke from a start position to an end position, rearming means (19) for rearming said device (18, 118), characterized in that said rearming means comprise the die (17), said die (17) acting as a rearming means for said device (18, 118) when the die (17) is taken back to the start position of said drawing stroke by the action of a utilizing machine (15) pulling step by step the metal wire (13).

2. A drawbench according to claim 1, said device (18, 118) comprising a lever (20), a cylinder and piston group (21) and a movement-amplification mechanical transmission (26, 126), said transmission (26, 126) comprising a toggle (30), said toggle comprising a first member (32) and a second member (36) rotatably connected to each other by a hinge (33).

3. A drawbench according to claim 2, characterised in that said lever (20) is of first type and is pivoted in the frame (16), having one end (20a) subjected to the action of the cylinder (22) and piston (24) group (21) and an opposite end (20b) acting on the die (17) to move it along the wire (13) in the drawing stroke, away from the utilizing machine (15).

4. A drawbench according to claim 2, characterised in that said first member (32) of the toggle (30) has a substantially triangular shape with a first vertex (32a), a second vertex (32b) and a third vertex (32c), and: said first member (32) of the toggle is rotatably connected to the drawbench (11, 111) substantially close to said first vertex (32a), in a predetermined position of the frame (16); the hinge (33) connecting the first member to the second member is provided substantially close to said second vertex (32b), a ball bearing (34) is mounted on the first member (32) close to said third vertex (32c), the ball bearing (34) being suitable for sliding along a guide (29) comprised in the mechanical transmission (26, 126).

5. A drawbench according to claim 4, characterised in that said second member (36) is substantially elongated in shape, having a first end (36a) rotatably connected to the end (20a) of the lever (20) subjected to the action of the cylinder and piston group (21), and having a second opposite end (36b) where said hinge (33) is provided.

6. A drawbench (11, 111) according to claim 2,
characterised in that said mechanical transmission (26, 126) comprises an equalizer (28), having a pivot (28a) in a predetermined position of the frame (16) and two opposite arms (28b, 28c).

7. A drawbench (11, 111) according to claim 6,
characterised in that said pivot (28a) and the ends of the two arms (28b, 28c) have a triangular arrangement, said equalizer (28) having a first arm (28b) with fixed operative length and a second arm (28c) with variable operative length.

8. A drawbench (11, 111) according to claim 7,
characterised in that said first arm (28b) is rotatably connected to the piston (24), whereas the second arm (28c) is equipped with a guide (29) for a ball bearing.

9. A drawbench (11, 111) according to claim 8,
characterised in that said guide (29) of said second arm (28c) of said equalizer (28) houses said ball bearing (34) of said first member (32) of said toggle (30).

10. A drawbench (111) according to claim 6, characterised in that said mechanical transmission (26, 126) comprises a wedge-shaped member (144) having two sides (144a, 144b) arranged like a wedge, said wedge-shaped member (144) being arranged between the group (21) and the equalizer (28).

11. A drawbench (111) according to claim 10, characterised in that said wedge-shaped member (144) is fixed to the piston (24) of the cylinder and piston group (21), the cylinder (22) being rotatably connected to the drawbench (111) by means of a pin (146).

12. A drawbench (111) according to claim 11, characterised in that one side (144a) of the wedge-shaped member (144) engages with a ball bearing (148), mounted on the first arm (28b) of the equalizer (28), the opposite side (144b) of the wedge-shaped member (144) being able to slide on a roller table (150).

13. A drawbench (11, 111) according to claim 2,
characterised in that the group (21) is actuated by a hydraulic control unit (38).

14. A drawbench (11, 111) according to claim 13,
characterised in that the cylinder (22) of the cylinder and piston group (21) has chambers that can be shortcircuited in the return stroke of the die (17).

15. A device (18, 118) for moving a drawing die (17) of a drawbench (11, 111) of a metal wire (13), said device (18, 118) being characterized in that it comprises a lever (20) of first type, a cylinder and piston group (21) and a movement-amplification mechanical transmission (26, 126), said transmission (26, 126) comprising a toggle (30), said toggle comprising a first member (32) and a second member (36) rotatably connected to each other by a hinge (33), and in that said device is adapted to be rearmed by the die (17) when the die (17) is taken back to the start position the drawing stroke by the action of a utilizing machine (15) pulling step by step the metal wire (13).

16. A method for operating a drawbench for a metal wire in a production line for small metal articles, the production line comprising a reel (14) hosting a metal wire (13), a drawbench (11, 111) for said metal wire comprising a mobile die (17) along a drawing stroke, and a utilizing machine (15) pulling step-by-step said metal wire, the method being
characterized in that:

- the mobile die (17) is moved along the drawing stroke by a device (18) of said drawbench, and

- said device is deactivated at the end of each drawing stroke and the mobile die (17) is taken back to the start of the drawing stroke by the action of said utilizing machine (15) pulling the metal wire (13), thereby rearming said device (18, 118) of the drawbench.

Ansprüche

1. Ziehbank (11, 111) für einen Metalldraht (13), der von einer Spule (14) abgezogen wird, wobei die Ziehbank einen Rahmen (16) und eine bewegliche Ziehmatrize (17), die beweglich am Rahmen (16) geführt ist, eine Vorrichtung (18, 118), die zum Bewegen der Matrize dient und dazu eingerichtet ist, die Matrize (17) entlang eines Ziehhubs von einer Ausgangsposition zu einer Endposition zu bewegen, und eine Rückführeinrichtung (19) umfasst, um die Vorrichtung (18, 118) wieder für den nächsten Arbeitshub vorzubereiten, dadurch gekennzeichnet, dass die Rückführeinrichtung die Matrize (17) umfasst, und die Matrize (17) als eine Rückführeinrichtung für die Vorrichtung (18, 118) fungiert, wenn die Matrize (17) durch die Wirkung einer Einsatzmaschine (15), die den Metalldraht (13) schrittweise einzieht, zur Ausgangsposition des Ziehhubs zurückgebracht wird.

2. Ziehbank nach Anspruch 1, wobei die Vorrichtung (18, 118) einen Hebel (20), eine Zylinder/Kolben-Baugruppe (21) und eine mechanische Kraftübertragung (26, 126) zur Bewegungsverstärkung umfasst, wobei die Kraftübertragung (26, 126) einen Gelenkhebel (30) aufweist, der ein erstes Element (32) und ein zweites Element (36) umfasst, die über ein Gelenk (33) drehbar miteinander verbunden sind.

3. Ziehbank nach Anspruch 2, dadurch gekennzeichnet, dass der Hebel (20) In einer ersten Bauart vorliegt und am Rahmen (16) schwenkbar gelagert ist, und ein Ende (20a) hat, das der Wirkung der Baugruppe (21) aus Zylinder (22) und Kolben (24) unterworfen ist, und ein entgegengesetztes Ende (20b), welches auf die Matrize (17) einwirkt, um sie beim Ziehhub entlang des Drahtes (13) weg von der Einsatzmaschine (15) zu bewegen.

4. Ziehbank nach Anspruch 2, dadurch gekennzeichnet, dass das erste Element (32) des Gelenkhebels (30) eine im Wesentlichen dreieckige Form mit einem ersten Eckpunkt (32a), einem zweiten Eckpunkt (32b) und einem dritten Eckpunkt (32c) hat, und: das erste Element (32) des Gelenkhebels im Wesentlichen nahe am ersten Eckpunkt (32a) an einer vorbestimmten Stelle des Rahmens (16) drehbar an die Ziehbank (11, 111) angekoppelt ist; das Gelenk (33), welches das erste Element mit dem zweiten Element verbindet, im Wesentlichen nahe des zweiten Eckpunkts (32b) vorgesehen ist, und ein Kugellager (34) am ersten Element (32) nahe des dritten Eckpunkts (32c) angebracht ist, wobei das Kugellager (34) dazu geeignet ist, entlang einer in der mechanischen Kraftübertragung (26, 126) enthaltenen Führung (29) abzurollen.

5. Ziehbank nach Anspruch 4, dadurch gekennzeichnet, dass das zweite Element (36) im Wesentlichen von langgestreckter Form ist und ein erstes Ende (36a) hat, das drehbar an das Ende (20a) des Hebels (20) angekoppelt ist, welches der Wirkung der Zylinder/Kolben-Baugruppe (21) unterworfen ist, sowie ein zweites, entgegengesetztes Ende (36b) hat, an dem das Gelenk (33) vorgesehen ist.

6. Ziehbank (11, 111) nach Anspruch 2, dadurch gekennzeichnet, dass die mechanische Kraftübertragung (26, 126) ein Ausgleichselement (28) umfasst, das einen Lagerzapfen (28a) an einer vorbestimmten Stelle des Rahmens (16) und zwei entgegengesetzte Arme (28b, 28c) hat.

7. Ziehbank (11, 111) nach Anspruch 6, dadurch gekennzeichnet, dass der Lagerzapfen (28a) und die Enden der beiden Arme (28b, 28c) eine dreieckige Anordnung haben, wobei das Ausgleichselement (28) einen ersten Arm (28b) mit fester wirksamer Länge und einen zweiten Arm (28c) mit veränderlicher wirksamer Länge hat.

8. Ziehbank (11, 111) nach Anspruch 7, dadurch gekennzeichnet, dass der erste Arm (28b) drehbar an den Kolben (24) angekoppelt ist, während der zweite Arm (28c) mit einer Führung (29) für ein Kugellager ausgestattet ist.

9. Ziehbank (11, 111) nach Anspruch 8, dadurch gekennzeichnet, dass die Führung (29) des zweiten Arms (28c) des Ausgleichselements (28) das Kugellager (34) des ersten Elements (32) des Gelenkhebels (30) aufnimmt.

10. Ziehbank (111) nach Anspruch 6, dadurch gekennzeichnet, dass die mechanische Kraftübertragung (26, 126) ein keilförmiges Element (144) mit zwei keilartig angeordneten Seiten (144a, 144b) umfasst, wobei das keilförmige Element (144) zwischen der Baugruppe (21) und dem Ausgleichselement (28) angeordnet ist.

11. Ziehbank (111) nach Anspruch 10, dadurch gekennzeichnet, dass das keilförmige Element (144) am Kolben (24) der Zylinder/Kolben-Baugruppe (21) befestigt ist und der Zylinder (22) über einen Zapfen (146) drehbar an die Ziehbank (111) angekoppelt ist.

12. Ziehbank (111) nach Anspruch 11, dadurch gekennzeichnet, dass eine Seite (144a) des keilförmigen Elements (144) an einem Kugellager (148) anliegt, das am ersten Arm (28b) des Ausgleichselements (28) angebracht ist, und die entgegengesetzte Seite (144b) des keilförmigen Elements (144) auf einem Rolltisch (150) abrollen kann.

13. Ziehbank (11, 111) nach Anspruch 2, dadurch gekennzeichnet, dass die Baugruppe (21) durch eine hydraulische Steuerung (38) betätigt wird.

14. Ziehbank (11, 111) nach Anspruch 13, dadurch gekennzeichnet, dass der Zylinder (22) der Zylinder/Kolben-Baugruppe (21) Kammern aufweist, die beim Rückhub der Matrize (17) miteinander verbunden werden können.

15. Vorrichtung (18, 118) zum Bewegen einer Ziehmatrize (17) einer Ziehbank (11, 111) eines Metalldrahts (13), wobei die Vorrichtung (18, 118) dadurch gekennzeichnet ist, dass sie einen Hebel (20) einer ersten Bauart, eine Zylinder/Kolben-Baugruppe (21) und eine mechanische Kraftübertragung (26, 126) zur Bewegungsverstärkung umfasst, wobei die Kraftübertragung (26, 126) einen Gelenkhebel (30) aufweist, der ein erstes Element (32) und ein zweites Element (36) umfasst, die über ein Gelenk (33) drehbar miteinander verbunden sind, und dass die Vorrichtung dazu eingerichtet ist, durch die Matrize (17) wieder für den nächsten Arbeitshub vorbereitet zu werden, wenn die Matrize (17) durch die Wirkung einer Einsatzmaschine (15), die den Metalldraht (13) schrittweise einzieht, zur Ausgangsposition des Ziehhubs zurückgebracht wird.

16. Verfahren zum Betreiben einer Ziehbank für einen Metalldraht In einer Produktionslinie für Metallkleinzeug, wobei die Produktionslinie eine Spule (14), die einen Metalldraht (13) vorhält, eine Ziehbank (11, 111) für den Metalldraht und mit einer längs eines Ziehhubs beweglichen Matrize (17), und eine Einsatzmaschine (15) umfasst, die den Metalldraht schrittweise einzieht, wobei das Verfahren dadurch gekennzeichnet ist, dass:

- die bewegliche Matrize (17) längs des ziehhubs durch eine Vorrichtung (18) der Ziehbank bewegt wird, und

- die Vorrichtung am Ende jedes Ziehhubs desaktiviert und die bewegliche Matrize (17) durch die Wirkung der den Metalldraht (13) einziehenden Einsatzmaschine (15) zum Ausgangspunkt des Ziehhubs zurückgebracht wird, wodurch die Vorrichtung (18, 118) der Ziehbank wieder für den nächsten Arbeitshub vorbereitet wird.

Revendications

1. Banc d'étirage (11, 111) pour un fil de métal (13) déroulé à partir d'un dévidoir (14), le banc d'étirage comportant un bâti (16) et une filière d'étirage mobile (17) guidée de manière mobile sur ledit bâti (16), un dispositif (18, 118) pour déplacer la filière, adapté pour déplacer ladite filière (17) le long d'une course d'étirage depuis une position de début jusqu'à une position de fin, des moyens de réarmement (19) pour réarmer ledit dispositif (18, 118), caractérisé en ce que lesdits moyens de réarmement comportent la filière (17), ladite filière (17) agissant comme des moyens de réarmement pour ledit dispositif (18, 118) lorsque la filière (17) est ramenée à la position de début de ladite course d'étirage par l'action d'une machine utilisatrice (15) tirant le fil de métal (13) pas à pas.

2. Banc d'étirage selon la revendication 1, ledit dispositif (18, 118) comportant un levier (20), un groupe cylindrelpiston (21) et une transmission mécanique d'amplification de mouvement (26, 126), ladite transmission (26, 126) comportant une bascule (30), ladite bascule comportant un premier élément (32) et un second élément (36) reliés l'un à l'autre de manière rotative par une articulation (33).

3. Banc d'étirage selon la revendication 2, caractérisé en ce que ledit levier (20) est d'un premier type et pivote dans le bâti (16), en ayant une extrémité (20a) soumise à l'action du groupe (21) formé d'un cylindre (22) et d'un piston (24), et une extrémité opposée (20b) agissant sur la filière (17) pour la déplacer le long du fil (13) pendant la course d'étirage, en l'éloignant de la machine utilisatrice (15).

4. Banc d'étirage selon la revendication 2, caractérisé en ce que ledit premier élément (32) de la bascule (30) a une forme sensiblement triangulaire avec un premier sommet (32a), un deuxième sommet (32b) et un troisième sommet (32c), et ledit premier élément (32) de la bascule est relié de manière rotative au banc d'étirage (11, 111) sensiblement près dudit premier sommet (32a), dans une position prédéterminée du bâti (16), l'articulation (33) reliant le premier élément au second élément est agencée sensiblement près dudit deuxième sommet (32b), un palier à billes (34) est monté sur le premier élément (32) près dudit troisième sommet (32c), le palier à billes (34) étant adapté pour glisser le long d'un guide (29) inclus dans la transmission mécanique (26, 126).

5. Banc d'étirage selon la revendication 4, caractérisé en ce que ledit second élément (36) a une forme sensiblement allongée, en ayant une première extrémité (36a) reliée de manière rotative à l'extrémité (20a) du levier (20) soumise à l'action du groupe cylindre/piston (21), et en ayant une seconde extrémité opposée (36b) où ladite articulation (33) est agencée.

6. Banc d'étirage (11, 111) selon la revendication 2, caractérisé en ce que ladite transmission mécanique (26, 126) comporte un dispositif d'équilibrage (28), ayant un pivot (28a) dans une position prédéterminée du bâti (16) et deux bras opposés (28b, 28c).

7. Banc d'étirage (11, 111) selon la revendication 6, caractérisé en ce que ledit pivot (28a) et les extrémités des deux bras (28b, 28c) ont un agencement triangulaire, ledit dispositif d'équilibrage (28) ayant un premier bras (28b) ayant une longueur de fonctionnement fixe et un second bras (28c) ayant une longueur de fonctionnement variable.

8. Banc d'étirage (11, 111) selon la revendication 7, caractérisé en ce que ledit premier bras (28b) est relié de manière rotative au piston (24), alors que le second bras (28c) est équipé d'un guide (29) pour un palier à billes.

9. Banc d'étirage (11, 111) selon la revendication 8, caractérisé en ce que ledit guide (29) dudit second bras (28c) dudit dispositif d'équilibrage (28) reçoit ledit palier à billes (34) dudit premier élément (32) de ladite bascule (30).

10. Banc d'étirage (111) selon la revendication 6, caractérisé en ce que ladite transmission mécanique (26, 126) comporte un élément en forme de coin (144) ayant deux côtés (144a, 144b) agencés comme un coin, ledit élément en forme de coin (144) étant agencé entre le groupe (21) et le dispositif d'équilibrage (28).

11. Banc d'étirage (111) selon la revendication 10, caractérisé en ce que ledit élément en forme de coin (144) est fixé au piston (24) du groupe piston/cylindre (21), le cylindre (22) étant relié de manière rotative au banc d'étirage (111) au moyen d'une goupille (146).

12. Banc d'étirage (111) selon la revendication 11, caractérisé en ce qu'un côté (144a) de l'élément en forme de coin (144) vient en contact avec un palier à billes (148), monté sur le premier bras (28b) du dispositif d'équilibrage (28), le côté opposé (144b) de l'élément en forme de coin (144) pouvant glisser sur une table à rouleaux (150).

13. Banc d'étirage (11, 111) selon la revendication 2, caractérisé en ce que le groupe (21) est actionné par une unité de commande hydraulique (38).

14. Banc d'étirage (11, 111) selon la revendication 13, caractérisé en ce que le cylindre (22) du groupe cylindre/piston (21) a des chambres qui peuvent être court-circuitées pendant la course de retour de la filière (17).

15. Dispositif (18, 118) pour déplacer une filière d'étirage (17) d'un banc d'étirage (11, 111) d'un fil de métal (13), ledit dispositif (18, 118) étant caractérisé en ce qu'il comporte un levier (20) d'un premier type, un groupe cylindre/piston (21) et une transmission mécanique d'amplification de mouvement (26, 126), ladite transmission (26, 126) comportant une bascule (30), ladite bascule comportant un premier élément (32) et un second élément (36) reliés l'un à l'autre de manière rotative par une articulation (33), et en ce que ledit dispositif est adapté pour être réarmé par la filière (17) lorsque la filière (17) est ramenée à la position de début pendant la course d'étirage par l'action d'une machine utilisatrice (15) tirant le fil de métal (13) pas à pas.

16. Procédé pour faire fonctionner un banc d'étirage pour un fil de métal sur une ligne de production de petits articles en métal, la ligne de production comportant un dévidoir (14) recevant un fil de métal (13), un banc d'étirage (11, 111) pour ledit fil de métal comportant une filière mobile (17) le long d'une course d'étirage, et une machine utilisatrice (15) tirant ledit fil de métal pas à pas, le procédé étant
caractérisé en ce que :

- la filière mobile (17) est déplacée le long de la course d'étirage par un dispositif (18) dudit banc d'étirage, et

- ledit dispositif est désactivé à la fin de chaque course d'étirage et la filière mobile (17) est ramenée au début de la course d'étirage par l'action de ladite machine utilisatrice (15) tirant le fil de métal (13), en réarmant ainsi ledit dispositif (18, 118) du banc d'étirage,

Drawing