Wire-feeding apparatus

Abstract: A handling apparatus for forging machines, especially for drawing wire (52) intended for realizing screws, rivets and like findings, comprises: a first cam (12) keyed on a first motor-driven rotary shaft (10), cooperating with a first angularly orientable lever (14), associated to a roller (16) and formed by a branch (14') having a rectilinear portion (18) suitable to place itself parallel with respect to a screw 820), guided by a support (22) and caused to rotate clockwise or anti-clockwise by an electric motor (24) or by hand; a sliding carriage (32), associated to screw (20), provided with a transversal tying pin (34) for an oscillating bar (36) bearing on its free end a needle (40) that strikes said portion (18) of the first lever (14); a second angularly orientable lever (14), cooperating with a carriage (50) movable in a direction parallel to the one of advance of the wire (52); means (56, 60) for grasping wire (52); a second cam (70) mounted on a second shaft or rotary side shaft (72) of the forging machine, cooperating with a needle (74) fixed to the lower end of a third lever (76) pivoted on a static support of said forging machine.

Description: BACKGROUND OF THE INVENTION The present invention relates to a forging machine comprising a handling apparatus. More particularly, the present invention relates to a forging machine utilized for the production of screws, rivets and like articles, and suitable to drag the wire which said articles are made from. As is known, the forging machines utilized to produce screws, rivets and like articles comprise a so-called "wire-tensioning" unit, which allows to cause the advance of the wire to a fixed extent, according to the length of the screw, rivet or articles to be realized. A forging machine comprising a wire-tensioning unit is known from US-A-4 942 796. Said forging machine has the features of the preamble of claim 1. In the forging machines of the known art, the wire-tensioning unit generally comprises special dragging rollers which have along the surface specific seats with a semicircular profile according to the diameter of the wire utilized each time. This solution involves severe drawbacks due to the very presence of said rollers, which must be replaced each time the wire diameter changes. Such replacement operation, while being not particularly complex, imposes the temporary stop of the operating cycle and an increase in the production costs. Besides, the replacement of the rollers must be carried out by expert and qualified personnel, very exact adjustments being required for the correct advance of the wire. A further drawback caused by the replacement of the rollers concerns the necessity of having at disposal a high number of roller couples according to the different diameters of the wire used; considering that there may be several dozens of wire diameters, one understands that the assortment of the couples of rollers necessary is extremely high and that the equipment costs are remarkable. Another known solution utilized for dragging the wire on the forging machines for the production of screws, rivets and like articles includes the use of mobile pliers, which grasp and release in alternation the wire to transfer it to the position required. However, also this solution has severe drawbacks, arising from the construction complexity of the whole and the ensuing costs, as well as the adjustment difficulty. SUMMARY OF THE INVENTION Object of the present invention is to obviate the above drawbacks. More particularly, object of the present invention is to realize a forging machine comprising a handling apparatus for the production of screws, rivets and the like, suitable to drag the wire, and such as to allow to drag said wire independently on its diameter. A further object of the present invention is to realize a forging machine as described above and such as not to require the availability and the replacement of the components according to the wire diameter. Still another object of the present invention is to provide a forging machine comprising an apparatus for handling wires suitable to be adjusted in a rapid and easy way. According to the present invention, these and still other objects that will be specified by the following description are achieved by forging machine comprising: a casing provided with a first motor-driven rotary shaft; a handling apparatus to drag the wire to a fixed extent according to the length of the screw, rivet or findings to be realised, comprising a first cam keyed on the first motor-driven rotary shaft, and means for grasping the wire; wherein: a) the handling apparatus comprises: a first angularly orientable lever, having a first branch provided at a free end thereof with a roller cooperating with the first cam, and a second branch having a rectilinear portion; a screw, guided by a support and rotatable alternatively clockwise and counter-clockwise, the rectilinear portion of the second branch of the first lever being parallel to the screw when the roller contacts the cam when said cam is at a maximum radius; a sliding carriage, pivoted on a pin and provided at a free end with a needle that strikes the rectilinear portion of the second branch of the first lever; a second angularly orientable lever, provided at one end thereof with a roller which is in contact with a bar movable by engagement with the first lever, said second lever having an opposite end thereof which cooperates with a carriage that is movable in a direction parallel to a direction of advance of the wire; and b) the means for grasping the wire comprises: a second cam, mounted alternatively on a second shaft or on a rotary side shaft of the forging machine; a tilting arm connected to the carriage; a third lever pivoted on a static support of said forging machine and having one end provided with a needle cooperating with said second cam and the opposite end cooperating with an end of the tilting arm, and opposite blocks respectively fixed to the carriage and to the tilting arm. BRIEF DESCRIPTION OF THE DRAWINGS The constructive and functional characteristics of the forging machines of the present invention shall be better understood thanks to the following description, wherein reference is made to the attached drawings, which represent a preferred non limiting example and wherein: Figure 1 shows a schematic side view of a section of the apparatus of the present invention, highlighting the front shaft provided with a control cam; Figure 2 shows the schematic view of the means for handling the wire; Figure 3 shows a further partly sectioned side view of the apparatus of the invention; Figure 4 shows the schematic top view of one of the levers cooperating with a cam applied to the side shaft of the apparatus of the invention. DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the above mentioned figures, the handling apparatus for forging machines of the present invention comprises a first rotary shaft 10, driven by a conventional motor (not shown in the figure) and whereon a cam 12 is keyed. A first lever 14, constituted by a shaped plate-like body pivoted in the intermediate part on a pin 15 fixed to the bedplate of the machine, comprises a first branch 14" provided at the free end with a roller 16 kept in constant touch with cam 12 by an elastic means 17, and a second branch 14' having a rectilinear portion 18 with results to be parallel to a screw 20 at the time when it is in a maximum travel position; such position is reached when roller 16 gets in touch with cam 12 in correspondence of its maximum radius. Screw 20, guided through a conventional support 22, is caused to rotate clockwise or anti-clockwise by an electric motor 24 or the like, which can be controlled through a PLC or a computer. As an alternative, said screw 20 may be handled by hand by means of a handwheel 26 applied on spindle 28 of the angular driving gear 30. A carriage 32 provided with a transversal pin 34 is slidingly associated to screw 20. The position of carriage 32 on screw 20 is adjusted by clockwise or anti-clockwise rotation of said screw. An end of a bar 36 is coupled to said pin 34 and said bar can oscillate about said pin. Bar 36 is provided at its free end, opposite to the one pivoted on pin 24, with a needle 40 sliding on plane 18 of the second branch 14' of lever 14. Said bar oscillates about pin 34 upon variation of the inclination of the second branch 14' whereon needle 40 slides. The variation of the inclination of the second branch 14' depends, in its turn, on the rotation of cam 12. The amplitude of the oscillation of bar 36 varies according to the position of carriage 32 along screw 20; said position is adjusted by rotating screw 20 through the electric motor 24 or the handwheel 26. A second, substantially L-shaped lever 44 pivoted in the intermediate part on a pin 46 fixed to the bedplate of the machine, comprises an end provided with a roller 42 that rests and is kept in constant touch under pressure on bar 36 by a spring 37. The opposite free end of said lever 33 strikes, through a needle 48, a carriage 50, sliding according to a direction parallel to the one of the wire advance, schematized by 52. A spring 54 associated to carriage 50 ensures the adherence of needle 48 to lever 44. The rotation of cam 12 imparts a tilting movement of lowering and elevation up to plane 18 of the second branch 14' of lever 14. Said movement causes the oscillation of bar 36 about pin 34 and therefore, through the action of roller 42, of the second lever about its pin 46. Such oscillation allows the advance and/or backward movement of carriage 50 to an extent that depends on the position of carriage 32 on screw 20. With reference to Figure 3, there is fixed on carriage 50 by known fasteners a metal block 56, provided on the exposed upper front with a V-shaped cavity. Opposed to block 56 and in a higher position with regard to it, a second block 60 is provided, fixed to an end of the tilting arm 62. Said arm 62 is tied to carriage 50 through a pin 64 or the like, and provided with a pad 66 at its end opposite to the one provided with the second block 60. A second cam 70 is mounted on a rotary side shaft 72 of the forging machine. A substantially L-shaped third lever 76 comprises two arms 78, 80, orthogonal to each other, and in the intermediate zone comprises between said arms it is pivoted on a conventional static support 82 of the forging machine. One 78 of said arms is provided, at the free end, with a roller 74 that slides on the surface of cam 70; an elastic means 92 keeps said roller 74 in continuous touch under pressure with the surface of cam 70. The free end of the other arm 76 is connected to a plate 84, which can strike mat 66 according to the position of cam 70. A pneumatic cylinder 86, tied to carriage 50, is provided with a stem 90 that strikes alternatively the tilting arm 62 in the position opposite to the one whereon plate 84 acts, and by acting on said tilting arm 62 allows the locking of wire 52 previously located, at the beginning of the cycle, between the first block 56 and the second block 60. The insertion of wire 52 between the first block 56 and the second block 60 takes place at the time when cam 70 pushes towards the outside arm 78 of lever 76, determining the lowering of plate 84 which, acting on pad 66, rises block 60. The return of arm 78 to its initial position is ensured by the elastic means 92. The pneumatic cylinder 86 constitutes a spring for the tilting arm 62; air pressure is adjusted by a conventional limiting device, while the activation of said cylinder is obtained by means of a solenoid valve or the like. When cam 70, rotating on itself, allows needle 74 to return to the initial position under the effect of the elastic means 92, lever 76 rises plate 84 connected to the same, which therefore frees pad 66. The pneumatic cylinder 86 can in this way extend its own stem 90 which acts on the tilting arm 62, causing the lowering of the second block 60. In this way, wire 52 is locked in the V-cavity 58 of the first and underlying block 56 of carriage 50. Cam 12, cooperating with the first lever 14, causes the advance of carriage 50. Lever 44 is constantly kept in back position by spring 54 which keeps backwards carriage 50; the latter, through needle 48, keeps roller 42 in touch with the plane defined by bar 36. Cam 70, mounted on the rotary side shaft 72 of the forging machine is timed in correlation with cam 12 of the rotary shaft 10. In particular, in the stage when cam 12 is so positioned as to allow the advance of carriage 50, plate 84 is raised and blocks 56 and 60 are closed on one another, following the action of stem 90 of the pneumatic cylinder 86 that causes the lowering of the tilting arm 62 provided with block 60. In this condition, wire 52 is stably kept between blocks 56 and 60. Vice-versa, when cam 12 is so positioned as to allow the return of carriage 50, blocks 56 and 60 have moved away from one another and do not clamp wire 52, as cam 70, in its rotation movement, acts on needle 74 of lever 76, lowering plate 84; the latter, pressing pad 66, causes the raising of the end of the tilting arm 62 and therefore of block 60. The handling apparatus of the present invention may be further provided, according to a preferred embodiment, with means suitable to exactly stabilize wire 52, when it is in an advanced position and must be submitted to the intervention of the molding equipment that is present on the forging machine. Said means, schematized in particular in Figures 4 and 5, comprise a further and third cam 96, applied to the same rotary side arm 72 of the forging machine, and a further substantially L-shaped lever 98, similar to lever 78, pivoted in the intermediate part on a pin 97 of the machine and provided at the free end with one of its branch with a needle 100, and at the opposite free end of the other branch with a dowel or screw 102. The exposure of said dowel or screw can be adjusted to strike an end of a tilting plate 104, pivoted on a pin 106 of the forging machine bearing the handling apparatus. A pneumatic cylinder 108 or the like, similar to cylinder 86 and adjusted and activated in the same way, strikes alternatively with its stem 120 the other end of the tilting plate 104. A second pair of blocks suitable to clamp wire 52, respectively indicated by 110 and 112, are superposed and aligned with each other in correspondence of the front free end of the tilting plate 104. The upper Block 110 of the second pair of blocks in its upper position, results to be mobile as it is integral with said plate 104, while the lower block 112, advantageously provided with a V-shaped cavity forming the seat for wire 52, is fixed and caused to be integral with the bedplate, indicated by 118, of the forging machine. Cam 96, in the same way as cam 70, is so timed as to cause the moving away from each other of blocks 110 and 112 of the second pair at the time when wire 52 advances, and the approaching by pressure of said blocks, clamping wire 52 once it has advanced up to the level establishes. A spring 114 is associated to the upper block 110, which allows its raising. During the working, dowel or screw 102 compresses the tilting plate 104 when cam 96 pushes laterally lever 98 starting from needle 100. The pressure exercised on said plate 104 allows the raising of the same in the front part aligned with block 110, and as a consequence also the latter, under the action of spring 114, rises, freeing or unlocking wire 52. On the contrary, when cam 96 allows the return of needle 100, lever 98 connected thereto, does not compress any longer the tilting plate 104 through the dowel or screw 102 which rises, and at this time there steps in the pneumatic cylinder 108 that extends its stem 120 by which it strikes said plate 104. As a consequence, the latter raises in the back part and lowers in the front part bearing the upper block 110, which overcomes the resistance of spring 114 and clamps wire 52 in cooperation with the lower fixed block 112. Through the adequate timing of cams 70 and 96, both couples of blocks 56, 60 and 112, 110 that close and open alternatively, remain simultaneously in clamping condition for a short time during the operation of the apparatus; this allows to ensure the absolute stability of wire 52 and therefore the utmost precision in the advance of the same. As can be inferred from what has been reported above, the advantages achieved by the invention are evident. The handling apparatus for forging machines, suitable in particular for the advance of the wire to form screws, rivets and like articles, is extremely versatile, as it can work in the presence of wires having different diameters, without requiring the replacement of components or complicated adjustments. Particularly advantageous is the possibility of stabilizing exactly the wire during the steps of its systematic advance, which is therefore extremely precise. While the present invention has been described with reference to a specific embodiment thereof proposed only by way of non limiting example, it is evident that many alternatives and variants will be obvious to those skilled in the art, in the light of the above description. Therefore, it is understood that the present invention intends to cover all the alternatives and variations that fall within the scope of the following claims.

Claims: A forging machine for the production of screws, rivets and similar articles from wire (52), comprising: a casing provided with a first motor-driven rotary shaft (10); a handling apparatus to drag the wire (52) to a fixed extent according to the length of the screw, rivet or findings to be realised, comprising a first cam (12) keyed on the first motor-driven rotary shaft (10), and means for grasping the wire; characterised in that a) the handling apparatus comprises: a first angularly orientable lever (14), having a first branch (14") provided at a free end thereof with a roller (16) cooperating with the first cam (12), and a second branch (14') having a rectilinear portion (18); a screw (20), guided by a support (22) and rotatable alternatively clockwise and counter-clockwise, the rectilinear portion (18) of the second branch (14') of the first lever (14) being parallel to the screw (20) when the roller (16) contacts the cam (12) when said cam (12) is at a maximum radius; a sliding carriage (32), pivoted on a pin (34) and provided at a free end with a needle (40) that strikes the rectilinear portion (18) of the second branch (14') of the first lever (14); a second angularly orientable lever (44), provided at one end thereof with a roller (42) which is in contact with a bar (36) movable by engagement with the first lever (14), said second lever (44) having an opposite end thereof which cooperates with a carriage (50) that is movable in a direction parallel to a direction of advance of the wire (52); and b) the means for grasping the wire (52) comprises: a second cam (70), mounted alternatively on a second shaft or on a rotary side shaft (72) of the forging machine; a tilting arm (62) connected to the carriage (50); a third lever (76) pivoted on a static support of said forging machine and having one end provided with a needle (74) cooperating with said second cam (70) and the opposite end cooperating with an end of the tilting arm (62), and opposite blocks (56, 60) respectively fixed to the carriage (50) and to the tilting arm (62). The forging machine according claim 1, wherein the second lever (44) bears at an end thereof a roller (42) that strikes the movable bar (36). The forging machine according to any of the preceding claims, wherein the third lever (76) is constituted by two arms (78, 80) orthogonal to each other, and is provided with elastic tensioning means (92). The forging machine according to any of the preceding claims, wherein the third lever (76) has a first end that is connected to needle (74), and a second end, opposite to the first end, that is connected to a plate (84) striking a pad (66) borne by said tilting arm (62). The forging machine according to any of the preceding claims, wherein a pneumatic cylinder (86) having a stem (90), is tied to carriage (50), said stem (90) alternatively striking the tilting arm (62). The forging machine according to any of the preceding claims, wherein a third cam (96) is keyed on the side shaft (72) and interacts with a fourth shaped lever (98) provided at one end with a needle (100), and at the opposite end with a dowel or screw (102) whose exposure is adjustable in order for it to strike a tiling plate (104) that is alternatively movable by a stem (120) of a pneumatic cylinder (108) or the like. The forging machine according to any of the preceding claims, further comprising a second pair of blocks (110, 112) for locking wire (52) and alternatively movable with respect to the opposite blocks (56); said second pair of blocks (110, 112) being superposed with each other and aligned in correspondence of the front end of the tilting plate (104), opposite to said needle (100). The forging machine according to any of the preceding claims 6 or 7 wherein elastic means (114) are associated with one of said second pair of blocks (110, 112). The forging machine according to claim 8, wherein the elastic means (114) associated with one of said second pairs of blocks (110, 112) is at least one spring. The forging machine according to any of the preceding claims, wherein at least one of the two blocks (56, 60) and (110,112) has a shaped cavity (58) for the positioning of the wire (52).

Inventors: GARLASCHI EUFEMIA, GARLASCHI, EUFEMIA
Applicants: CARLO SALVI S P A, CARLO SALVI S.P.A.
Application year: 2000
Main classification: B21J13
IPC codes: B21F23, B21K27, B21J13