Multistage press and method for producing a formed part

Abstract

A multistage press for the bulk deformation of a piece of wire includes a wire feed with associated apparatus for cutting to length, and a transfer device—having grippers—for receiving a piece of wire that has been cut to length and transferring the latter to subsequent forming stages, there being arranged, on that side of the cutting-to-length apparatus opposite from the wire feed, a device for partially heating a length of wire. A method produces a formed part with a multistage press of this type.

Claims

1. A multi-stage press for solid forming of a wire section, comprising: a wire feed with a related apparatus for cutting to length, as well as a transfer device having grippers, for holding of the wire section cut to length and for transfer of the wire section to subsequent forming stages, wherein means for heating of a wire end section of the wire section are arranged on the side of the apparatus for cutting to length that lies opposite the wire feed, wherein the wire feed, the forming stages, and the apparatus for cutting to length can be controlled independently of one another, wherein the means for heating of the wire end section of the wire section are stationary and comprise an induction coil, and wherein the wire feed is set up for temporary introduction of the wire end section of the wire section into the induction coil, and the wire feed comprises a servo-drive configured for defined forward and backward movement of the wire section without movement of the means for heating of the wire end section of the wire section.

2. The multi-stage press according to claim 1, wherein the wire feed can be controlled by way of a controller connected with the wire feed, in which controller a defined dwell time of the wire end section in the induction coil and/or a target temperature can be stored.

3. The multi-stage press according to claim 2, wherein means for detecting the temperature of the wire end section situated in the induction coil are provided, which means are connected with the controller, and wherein a regulator is integrated into the controller, by means of which regulator the wire feed can be controlled as a function of the temperature of the wire end section.

4. The multi-stage press according to claim 2, wherein the controller is connected with the apparatus for cutting to length, and set up in such a manner that after heating at the wire end section of the wire section has taken place, the wire section is cut to a defined length.

5. A method for the production of a formed part using a multi-stage press, wherein a wire is first heated on the end side, wherein the wire is passed from a coil, by way of a wire feed, to a stationary induction coil arranged on the side of an apparatus for cutting the wire to length that lies opposite the wire feed, where the wire is heated to a defined temperature on the end side, on a wire end section, wherein the wire is passed in a forward movement to the stationary induction coil by way of a servo-drive, and wherein the wire is moved into the stationary induction coil in accordance with the desired length of the wire end section to be heated, and after the desired temperature has been reached, the wire is moved out of the stationary induction coil in a backward movement defined by the servo-drive without movement of the stationary induction coil, subsequently a wire section having a desired length is cut at a defined distance from the heated wire end section, and the wire section with the heated wire end section is passed to multiple forming stages, one after the other, by way of a transfer device having grippers for holding the wire section cut to length and for transfer of the wore section to the multiple forming stages.

6. The method according to claim 5, wherein the temperature of the wire end section takes place by way of a contact-free temperature sensor.

7. The method according to claim 5, wherein the dwell time required to reach the desired temperature within the induction coil is determined empirically and stored in a controller connected with the servo-drive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other further developments and embodiments of the invention are discussed below. An exemplary embodiment of the invention is shown in the drawings and will be described in detail below. The figures show:

(2) FIG. 1 the schematic partial representation of a multi-stage press, with an induction coil arranged on it, for end-side wire heating;

(3) FIG. 2 the schematic representation of the arrangement for wire feed, apparatus for cutting to length, and induction coil, for the production of a wire section heated on the end side, within the multi-stage press from FIG. 1, in the operating states: a) advancing the wire from the coil; b) heating the end-side wire section in the induction coil; c) moving the wire backward, with setting of the desired length, and d) cutting the wire section to the desired length, along with take-over by the transfer device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(4) The horizontal multi-stage press 1 selected as the exemplary embodiment is a multi-stage press with a horizontal design, as it is used for the production of screws and similar small parts. The structure of such horizontal multi-stage presses is sufficiently known to a person skilled in the art and is described in EP 0 215 338 A1, for example. In this regard, the forming tools are arranged next to one another. A transverse transfer device brings the workpieces from one forming stage to the next forming stage. Usually, these presses operate with a transverse transport carriage, which has a number of transfer grippers that corresponds to the number of forming stages, which grippers project between the punch tools and the dies. For this reason, a detailed description of such a horizontal multi-stage press will not be given here. The description below focuses on the essential components of the multi-stage press according to the invention.

(5) In FIG. 1, certain sections of a multi-stage press 1 according to the invention are shown. The die block 11 having individual forming stages 12 can be seen; transfer grippers 71 of the transverse transfer device 7 are arranged between the stages. A wire feed is arranged ahead of the first forming stage 12; in the exemplary embodiment, this feed 2 is configured as a servo-drive 21. The wire feed 2 picks up a wire 8 that has been unwound from a coil, not shown. Wire shears 3 that can be controlled separately, for cutting the wire 8 to length, are arranged ahead of the wire feed 2. The transfer grippers 71 of the transfer device 7 are positioned behind the wire shears 3, viewed from the wire feed 2; these grippers are set up for picking up a wire section 81 that has been cut to length by the wire shears 3. An induction coil 4 is arranged, in turn, behind the transfer grippers 71, which coil is positioned in such a manner that a wire picked up by the wire feed 2 can be pushed into the induction coil 4 by way of the servo-drive 21. The wire feed 2, the wire shears 3, and the induction coil 4 are connected with a control and regulation device 6, which in turn is connected with a pyrometer 5 arranged on the induction coil 4 for measuring the temperature of a wire end section 82 that has been introduced into the induction coil 4. Furthermore, the control and regulation device 6 is also connected with the transverse transfer device 7 for controlling the transfer grippers 71. The control and regulation device 6 is part of the overall machine controller, not shown, by way of which control of the punch block, not shown, that carries the individual forming punches also takes place.

(6) In FIG. 2, the method for production of a screw resistant to high temperatures by means of forming of a wire composed of a nickel-based alloy is outlined. A wire 8 is pushed forward from a coil, not shown, by way of the wire feed 2, through the wire shears, all the way through to the induction coil 4, until an end-side wire end section 82 having a defined length projects into the induction coil 4. For this purpose, the length of the wire end section 82 to be heated as well as the desired temperature are stored in the control and regulation device 6, which also controls the servo-drive 21 of the wire feed 2 (FIG. 2a). Afterward, the servo-drive 21 is stopped, so that the wire end section 82 remains in the induction coil 4. The temperature of the wire end section 82 is continuously measured by way of the pyrometer 5. The measured values are reported to the control and regulation device 6, which compares them with the stored reference temperature of the wire end section 82 (FIG. 2b).

(7) After the stored reference temperature of the wire end section 82 has been reached, the servo-drive 21 of the wire feed 2 is controlled to move in the opposite direction by way of the control and regulation device 6, so that the wire 8 is pulled back through the wire feed 2, until the wire section that is situated behind the wire shears 3 has reached the length stored in the control and regulation device 6 (FIG. 2c). Now the wire shears 3 are activated by way of the control and regulation device 6, and thereby the wire section 81 is cut off at the stored length. The wire section 81 that has been cut to length in this way is gripped by the gripper 71 of the transfer device 7 and transferred to the first forming stage 12 of the die block 11 of the multi-stage press 1. At the same time, renewed advancing of the wire 8 in the direction of the induction coil 4 takes place, until once again the wire end section 82 projects into the induction coil 4 with the desired length. During heating of this next wire end section 82, further forming of the wire section 81 takes place by way of the further forming stages 12. Further forming of the wire section 81, which has been placed into the first forming stage 12 and heated on the end side, by way of the forming stages 12 of the multi-stage press, is known to a person skilled in the art and does not require any further explanation at this point.

(8) At this point, it should be noted that the drive of the punch block, not shown, which holds the individual forming punches, is mechanically uncoupled from the servo-drive of the wire feed 2 as well as from the drive of the transverse transfer device 7. It should furthermore be mentioned that the multi-stage press according to the invention can be used both for conventional production of formed parts by means of a continuous cold-forming method. For this purpose, the wire 8 is directly advanced to such an extent that a wire section 81 having the desired length is arranged behind the wire shears 3, and afterward a wire section 81 is directly cut to length.