DEVICE TO OPERATE THE MOVEMENT OF A DRAW CARRIAGE

Abstract: The invention concerns a device to operate the movement of a draw carriage, the device comprising at least one control drum (19) which bears on its circumference a cam (18) closed in a ring extending over a revolution of 360°C, the cam (18) cooperating with at least one thrust roller (12) substantially fixed solidly to the carriage (10) that bears grippers (22). The cam (18) has a circumferential groove with two paral­ lel opposed guide paths (16-17) positioned substantially radial­ ly at right angles to the axis (20) of the drum (19), one of which guide paths (16) cooperates with the thrust roller (12), where­ as the other guide path (17) cooperates with a resiliently re­ sisted resetting roller (13).

Description: "DEVICE TO OPERATE THE MOVEMENT OF A DRAW CARRIAGE" This invention concerns a device to operate the movement of a draw carriage. To be more exact, the invention concerns a device to operate the carriage which bears the grippers that clamp the piece to be drawn, together with a drum that bears a control cam. Various systems to govern the reciprocating movement of the carriage that bears the grippers are known and are derived substantially from the cooperation of at least one cam-follower roller with a cam developed on a drum. In particular, reference is made here to a cam element developed over one single full revolution of the drum. The present invention therefore concerns a movement device to impart a reciprocating to-and-fro movement to the carriage which bears the grippers in draw machines, the device comprising at least one element to bear cams which is able to rotate with a closed circuit. The cams cooperate at least with a roller supported by the carriage so as to transmit the to-and-fro travel to the carriage. The device of this invention also has the purpose of simplifying the operations of opening and closing the grippers, which are able to engage the material to be drawn whenever the carriage moves forwards. Various known devices have the purpose of performing the operation of a draw carriage by means of cams on a rotatable drum. For instance, a proposal in IT 730.874 is known which discloses a drum on which a cam is developed with a closed ring and protrudes with two surfaces lying substantially at right angles to the axis of the drum and positioned on the two sides of the protrusion. These surfaces have a discontinuous development with substantially parallel tracts and tracts which approach each other, this being made necessary by the geometry of the cam. Although this system may be deemed advantageous for medium and low speeds, yet it entails noteworthy complications both during its embodiment and also when it is being installed and employed; moreover, it gives an unsatisfactory result when the gripper-bearing carriage has to be operated at high and medium speeds. In particular, it involves problems linked to the construction of the cams themselves owing to the varying development of the cam walls, the question of spare parts and supplies being problematical. US 3,374,684 is known and discloses a carriage with two rollers operated respectively by two cams which, as in the patent cited earlier, are made on opposed faces of a helicoidal projection on a rotatatble drum. This invention comprises two carriages which move in opposite directions and are operated by two coaxial cams. It entails the same shortcomings and drawbacks as IT 730.874 cited above. GB 829,519 is known and discloses three carriages having their movements lying at angles of 1200 to each other. The purpose of this is to ensure a continuous grip on the material to be drawn, thus entailing the advantage of actually having two carriages always engaged with the material. However, this system involves the drawback that, when the about which a resetting roller 13 can rotate. The compensation carriage 14 is resisted resiliently by compensation spring means 15, which may possibly be guided on a suitable pin 115. The thrust roller 12 cooperates with a thrust guide path 16 comprised in a circular cam 18. In every radial position the thrust guide path 16 lies substantially at right angles to the axis 20 of the drum 19. The drum 19 having its axis 20 thus comprises a circular cam 18 which is closed over one full revolution of the drum 19. This cam 18 has, in front of the thrust guide path 16, a resetting and compensation guide path 17, with which a reset- ting roller 13 cooperates. A plate 122 which supports the grippers 22 can cooperate with the plate 11 which bears the grippers 22 so as to obtain advantageous clamping action by the same 22. The carriage 10 which bears the grippers 22 has normal guide wheels 23-123, which cooperate with linear guides 121. According to the invention two guide systems can cooperate on one and the same axis so that while one system is in a drawing condition, the other system is in a resetting condition, thus providing a continuity of drawing which otherwise would not be possible. Figs.5 and 6 show a possible embodiment to actuate the opening and closing of the grippers, or vice, 22 according to the invention. The grippers, or vice, 22 are fitted above the base 110 of the carriage 10 in a known manner and, by moving within wedgeshaped guides which are not shown here, provoke the clamping or unclamping of the piece to be drawn, such piece to be drawn lying substantially along the drawing axis 34. The grippers 22 have jaws 222 of a replaceable type fitted to them so as to grip the piece to be drawn. A damped wedge-shaped means 29 is envisaged in cooperation with a shoulder 26 of the path 16 (but could also be present on the drum 19) and is able to swing on an oscillation pivot 28 and has a wedge-shaped form, as we said above. The form of the damped wedge-shaped means 29 is such that, during the coordinated forward movement of the gripper-bearing carriage 10 in relation to the thrust path 16, the presence of an actuation roller 35 cooperating with the grippers 22 causes an auxiliary sideways displacement of the grippers 22 towards their closure position. The position of the damped wedge-shaped means 29 in relation to the thrust path 16 is such as to actuate the actuation roller 35 in cooperation with the instantaneous moment at which the grippers 22 have to clamp the piece to be drawn. The damped wedge-shaped means 29 cooperates with a damper spring 30, which serves to cushion the impact of the actuation roller 35 and also serves to facilitate non-destructive clamping of the grippers 22 against the piece to be drawn. Fig.5 shows how the wedge 29 able to swing is lodged in a lateral path 27 provided in a shoulder 26 of the thrust path 16. In the embodiment of Fig.5 the wedge 29 is shown in its position of maximum travel for its clamping action, whereas the actuation roller 35 is shown in its closure position and (with lines of dashes) in its position at the start of closure operations. When the carriage 10 reaches the end of its run for the active drawing of the piece to be drawn, the inertias involved and the cooperation of an opener spring means 32 (loaded during clamping action) cooperating with an opener shaft 33 cause the grippers 22 to be thrust in a direction opposite tc the action exerted beforehand by the wedge 29. The opening of the grippers 22 themselves is obtained in this way. The mutual transmission of movements and the coordination of the movement of the grippers 22 are obtained by suitable terminal drawing means 31, which transmit the movements from one gripper 22 to the other and create the necessary suitable cooperation. If so required, two actuation rollers 35 can be provided and be positioned differently, each of them cooperating with a gripper 22, the two rollers 35 working in coordination either with one double damped wedge means 29 or with two damped wedge means 29. According to a variant shown in Figs.7, 8 and 9 a path 127 is provided on the same shoulder 26 of the path 16. This path 127 governs the movement of a roller 135, which in its turn is solidly fixed to a slider means 37, which can slide lengthwise along the carriage 10 and, in this case, is connected from below to the grippers 22 in a known manner. For instance, this connection can be made with restrained joint means such as pins, projections, locking pins, etc. For the positive actuation of closure of the grippers 22 the path 127 comprises suitable raised portions to act on the roller 135, which is displaced towards the left in Fig.8. In this way the slider 27 too forces the grippers 22 towards the left (see Fig.9) in their closure direction. The timing embodied in the path 127 enables the instant of closure of the grippers 22 to be determined. The conformation of the path 127 enables the grippers 22 to be closed gently and in a non-destructive manner against the piece to be drawn. In the example of Fig.9 the grippers 22 cooperate slidably with lengthwise guide means 38 positioned at an angle to the draw axis 34 so as to create a wedging of the grippers 22 themselves between the guide means 38. Sliding of the grippers 22 is facilitated by rolling means 39 such as rollers or balls. Opener spring means 32 with guide pins 132 cooperate with the inertia of the grippers 22 so as to open the latter 22, as we said earlier. The spring means 32 also perform a cushioning action when the grippers 22 are being closed, so as to obtain a gentle engagement of the piece to be drawn. Figs.8 and 9 show actuator means 36 which drive gripper jaws 136 for initial engagement of the piece to be drawn at the beginning of draw operations. After such engagement and when the carriage 10 has been retracted for the first time, the jaws 136 are opened for the start of normal working. The variant shown also envisages adjustment means to take up the play and to set the initial opening of the grippers 22. Such adjustment is carried out by means of a threaded sleeve 42 through which the drawn material passes. The sleeve 42 is solidly fixed to the carriage 10 and is threaded outwardly. A ring nut 41, which is shown diagrammatically, cooperates with the threaded surface of the sleeve 42 and enables the movement of the slider 37 in relation to the sleeve 42 itself and therefore to the carriage 10 to be adjusted. The fitted jaws 222 (see Fig.9) can be removed from above in the embodiment shown after removal of clamp means 40 screwed onto the rear part of the grippers 22. INDEX 10 - gripper-bearing carriage 110 - base of carriage 11 - gripper-bearing plate 12 - thrust roller 13 - resetting roller 14 - compensation carriage 15 - compensation spring 115 - guide pin 16 - thrust path 17 - resetting and compensation path 18 - circular cam 19 - cam-bearing drum 20 - axis of drum 21 - guides for carriage 14 121 - linear guides for carriage 10 22 - grippers 122 - support plate 222 - fitted jaws 23 - guide wheels 123 - guide wheels 24 - pivot 25 - pivot 26 - shoulder of path 27 - lateral path 127 - lateral path 28 - oscillation pivot 29 - wedge able to swing 30 - damper spring 31 - terminal drawing means 32 - damper and opener spring 132 - guide pins 33 - opener shaft 34 - drawing and clamping axis 35 - actuation roller 135 - actuation roller 36 - actuator means 136 - gripper jaws 37 - control slider means 38 - lengthwise guides 39 - rolling means 40 - clamp means 41 - adjustment ring nut 42 - guide sleeve

Claims: CLAIMS 1 - Device to operate the movement of a draw carriage, the device comprising at least one control drum (19) which bears on its circumference a cam (18) closed in a ring extending over a revolution of 360 , the cam (18) cooperating with at least one thrust roller (12) substantialy fixed solidly to the carriage (10) that bears grippers (22), in which device the cam (18) has a circumferential groove with two parallel opposed guide paths (16-17) positioned substantially radially at right angles to the axis (20) of the drum (19), one of which guide paths (16) cooperates with the thrust roller (12),whereas the other guide path (17) cooperates with a resiliently resisted resetting roller (13). 2 - Device to operate the movement of a draw carriage as claimed in Claim 1, in which the resetting roller (13) is resisted resiliently by compensation spring means (15) cooperating with a compensation carriage (14) which bears the resetting roller (13). 3 - Device to operate the movement of a draw carriage as claimed in Claim 1 or 2, in which the elastic resistance against the resetting roller (13) is exerted on a plane passing through the axis (20) of the drum (19) and comprising the axis of the thrust roller (12). 4 - Device to operate the movement of a draw carriage as claimed in any claim hereinbefore, in which the control of the grippers (22) includes an actuation roller (35) cooperating with a damped wedge-shaped means (29) during the clamping phase of the grippers (22) in the neighbourhood of one of the ends of the travel of the carriage (10), while opener spring means (32) cooperate with the neighbourhood of the other end of the travel of the carriage (10) and with the inertia involved so as to open the grippers (22) (Fig.5). 5 - Device to operate the movement of a draw carriage as claimed in Claims 1 and 4, in which the actuation roller (35) is structurally fixed solidly to at least one-ripper¯¯¯t2). 6 - Device to operate the movement of a draw carriage as claimed in Claim 4 or 5, in which the damped wedge-shaped means (29) has damper spring means (30) and advantageously an oscillation pivot (28). 7 - Device to operate the movement of a draw carriage as claimed in any claims hereinbefore, in which the opener spring means (32) are loaded during the clamping phase and act in the opposite direction to the action exerted by the damped wedgeshaped means (29) on the actuation roller (35). 8 - Device to operate the movement of a draw carriage as claimed in any claim hereinbefore, in which the grippers (22) are connected together by drawing means (31). 9 - Device to operate the movement of a draw carriage as claimed in any claim hereinbefore, in which the actuation roller (135) cooperates with a path (127) provided on the control drum (19) (Fig.8). 10 - Device to operate the movement of a draw carriage as claimed in Claims 1 and 9, in which the actuation roller (135) is solidly fixed to a slider means (37) which cooperates at least momentarily with the grippers (22) (Figs.7 to 9). 11 - Device to operate the movement of a draw carriage as claimed in Claims 1 and 10, -which comprises means (41-42) to adjust the travel of the slider means (37).

Inventors: PARASKEVAS, ELEFTERIOS
Applicants: DANIELI & C. OFFICINE MECCANICHE S.P.A., DANIELI NATISONE SPA
Application year: 1983
Main classification: B21C1
IPC codes: B21C1, F16H25, F16H53