Patent Grant
9457393
The invention relates to a forming machine for forging, in particular stretch-forging, workpieces.
Forging is a process for hot forming forgeable metal materials, in particular metal alloys such as steels. Stretch-forging, also referred to as drawing out or drawing for short, is a process belonging to the category of open-die forging, in which only a small part of the volume of the workpiece is formed between two drawing tools (or: drawing saddles) in successive forging steps. During stretch-forging, the workpiece is held at one end or at both ends, generally by gripping tongs of manipulators or robots, and is moved between the drawing tools in individual steps in a drawing direction and is then upset by the drawing tools perpendicularly to the drawing direction in partial areas that follow on from one another counter to the drawing direction. During this process, the material of the workpiece flows parallel to the drawing direction, and the workpiece thus becomes thinner in cross section perpendicularly to the drawing direction and longer parallel to the drawing direction. Generally, the drawing tools generally have somewhat spherical or convexly curved surfaces and are also referred to as stretching or drawing saddles, wherein the upper saddle is referred to as the top saddle and the lower saddle is referred to as the bottom saddle. The successive individual forming operations or “bites” leave behind on the workpiece a wavy structure with grooves which mirrors the shape of the saddles. The surface of the workpiece is therefore often smoothed in a subsequent operation using smoothing tools, which generally have larger dimensions than the drawing tools. Forging presses or forging hammers are generally used as forming machines for drawing, in which case the drawing tools are then provided on these machines. The top saddle is generally arranged on a movable upper tool carrier or top and the bottom saddle is generally arranged on a lower tool carrier, which is usually immobile, the anvil or press bed. However, it is also possible for both drawing tools to move. In order to reverse-forge an increase in width, which is generally unwanted when drawing the workpiece, the forging can be turned through 90° after each blow (or after each drawing pass). Stretch-forging or drawing is often used as a pre-shaping process or for preliminary distribution of the material before a closed-die forging operation, in which the workpiece is given its final form (in respect of this general prior art, see, for example, A. Herbert Fritz and Günter Schulze, “vdi-Fertigungstechnik” [vdi Manufacturing Technology], Springer-Verlag, 5th edition, 2001, pages 402 to 405).
Typically, rod-shaped or cuboidal blanks are lengthened axially in the stretch-forging process and, if required, are already provided with contours, as viewed in a longitudinal section in the drawing direction.
Both hydraulic drives and mechanical drives are known as drives for the upper and, where required, also the lower tool carrier.
It is the underlying object of the invention to indicate a new hydraulic forming machine, by means of which, in particular, short cycle times can be achieved.
According to the invention, this object is achieved by a forming machine having the features of patent claim 1. Advantageous embodiments and developments will become apparent from the patent claims dependent on patent claim 1.
The forming machine as claimed in patent claim 1 is suitable and intended for forging, in particular stretch-forging, metal workpieces which have been heated and/or are in a flowable condition, and comprises
In a preferred embodiment, at least part of the hydraulic drive element is arranged in a hydraulic chamber filled with hydraulic medium, and the hydraulic chamber is partitioned or divided by the drive element into a front subchamber and a rear subchamber.
It is then expedient if a reset device is in each case assigned to the front subchamber of the hydraulic chamber for the purpose of resetting the drive element, wherein the reset device can, in particular, be a hydraulic reset device, in particular a reset device having a hydraulic pump which sets the hydraulic pressure in the front subchamber to at least one particular reset pressure value. However, a mechanical reset device with mechanical springs or the like is also possible.
In an advantageous embodiment, the rear subchamber of each hydraulic chamber is assigned a hydraulic setting device for the purpose of setting the end position, in particular the axial end position, of the drive element in the working motion, in particular by setting the supplied volume or pressure of the hydraulic medium in the rear subchamber. The hydraulic setting device generally comprises a hydraulic pump and a port on the rear subchamber and an associated hydraulic connection of the hydraulic pump to the port. The hydraulic pump is, in particular, a hydraulic servopump, e.g. an axial piston pump, and has a position-controlled servomotor, which holds the pump rotor or piston firmly in a predetermined position. The hydraulic pump is then expediently also used to fill the rear subchamber with the hydraulic medium.
In another embodiment, during its eccentric motion, the or each eccentric element drives a transmission element hydraulically coupled to the hydraulic drive element in a transmission motion. During the transmission motion, the transmission element moves backward and forward, in particular in the hydraulic chamber or in a stroke chamber hydraulically connected to the hydraulic chamber and likewise filled with the hydraulic medium, preferably in a substantially linear motion, wherein, in particular, the transmission element or the stroke chamber is hydraulically coupled or connected to the rear subchamber of the hydraulic chamber.
The driving device furthermore preferably comprises at least one electric drive motor, wherein the at least one eccentric element can be driven or is driven by the at least one drive motor via at least one drive shaft and rotates with the drive shaft in an eccentric motion eccentric with respect to the axis of rotation of the drive shaft.
In a special development, each forming tool is provided with an associated tool carrier, on which the forming tool is fixed, preferably releasably, and which is coupled for the purpose of driving to the associated hydraulic drive element. This coupling is achieved, in particular, through releasable connection of the tool carrier to a fixing flange, which is fixed on the end of a sliding rod which, preferably being guided and supported axially by an axial bearing, in turn has, at an end remote from this fixing flange, a further fixing flange, which, in turn, is releasably connected to an associated fixing flange at the front end of the drive element.
In a preferred variant, the forming tool is supported and guided on the associated tool carrier in a manner which allows it to be moved, in particular vertically and/or perpendicularly to the approach motion, or the tool carrier is appropriately configured in such a way that two parts can be moved relative to one another and one of these parts carries the forming tool. This is advantageous, in particular, in combination with an embodiment in which the forming tool has a, preferably upper, drawing surface and a, preferably lower, planishing surface and is then supported movably and can be fixed in two positions in order to arrange the drawing surface or the planishing surface in the operative position for the approach motion.
For the automation of this movement, an adjusting device for adjusting (and fixing) the forming tools into (in) various positions of displacement, in particular in the vertical direction and/or perpendicularly to the approach motion, is preferably provided. The adjusting device comprises, for example, a guide rod, which connects the two tool carriers to one another and which can be moved by means of a drive unit.
In a special embodiment, at least one or in each case one position measuring device is provided for measuring the position of the drive element, wherein the measured position is preferably used as a parameter for monitoring or controlling the forming process.
The forming machine according to the invention generally is or comprises a work-defined or travel-defined forming machine, preferably a forging hammer, in particular an upper hammer or counterblow hammer, or a forging press, i.e. the forming tools thereof operate either with a pressing or travel-defined action, on the one hand, or with a striking or work-defined action, on the other hand.
In addition to the forming machine according to the invention, a system according to the invention for forming, in particular stretch-forging, metal workpieces which have been heated and/or are in a flowable condition can also comprise at least one handling device for gripping a workpiece and preferably for performing a relative motion of the workpiece relative to the at least two forming tools of the forming machine.
The invention is explained more fully below with reference to illustrative embodiments. In the process, reference is also made to the drawings, in which:
each of the figures being schematic. Mutually corresponding components and dimensions are provided with the same reference signs in
After having been heated in a furnace and thereby converted to a flowable condition for the purpose of hot forming, the blank or the workpiece 2 is gripped by one or two gripping devices (not shown) in a respective gripping area situated at one end of the workpiece 2 and is held in a position aligned along an axis A, which is a substantially horizontal position in the illustrative embodiments shown. The axis A extends along and, preferably centrally, through the workpiece 2.
If the forming machine is used for stretch-forging the workpiece 2, the at least one gripping device not only holds the workpiece 2 in the appropriate position along the axis A but moves the workpiece 2 axially or in a linear manner with respect to the axis A in individual axial path segments for successive working of the workpiece 2 in individual stretch-forging steps or drawing steps by means of drawing tools.
In the illustrative embodiment shown in
In
For each drawing tool 4A and 4B, the forming machine 4 comprises an associated tool carrier 5A and 5B, respectively, on which the drawing tool 4A or 4B is releasably fixed, and respective drives for driving the tool carrier 5A or 5B together with the tool 4A or 4B in the drawing motion R and in the opposite return motion.
Each drawing tool 4A and 4B has an upper drawing surface 40 and a lower planishing surface 41. With the drawing surfaces 40, the workpiece 2 is stretched and formed in its shape. The planishing surfaces 41 of the drawing tools 4A and 4B are used to smooth or planish the surface of the drawn workpiece 2 afterwards. In order to arrange the drawing surface 40 or the planishing surface 41 on the axis B provided for the drawing motion R, the drawing tool 4A or 4B is configured to allow movement, in particular vertical movement, relative to the tool carrier 5A and 5B or, alternatively, the tool carrier 5A and 5B is configured in such a way that two parts can be moved relative to one another and one of these parts carries the drawing tool 4A or 4B. For adjustment of the drawing tools 4A and 4B, in particular in the vertical direction, perpendicularly to the axis B, an adjusting device 47 is provided, comprising a guide rod 48 which connects the two tool carriers 5A and 5B to one another. The drawing tools 4A and 4B are fixed on the tool carriers 5A and 5B, which have a linear guide in the vertical direction. By means of the drive unit 47, which operates pneumatically, hydraulically or electromechanically, the tool carriers are moved upward or downward, depending on the desired mode of operation of the system (drawing or planishing). The vertical movement is introduced by means of the guide rod 48. The use of the guide rod 48 allows the approach motion R. The two tool carriers 5A and 5B can be locked in each of the two end positions. This locking system can be driven hydraulically or pneumatically.
The adjusting device 47 is fixed on a transverse plate 43 which, in turn, is fixed laterally on two vertically extending holding plates 42A and 42B. The structure comprising the holding plates 42A and 42B and the transverse plate 43 is reinforced and stabilized by four rod-shaped fixing elements 46 and delimits the actual working zone of the forming machine. The four fixing elements 46 are fixed on vertical stand plates 52A and 52B of a surrounding stand 51, said plates standing on the ground via stand feet. Extending above the transverse plate 43 and the adjusting device 47 is a transversely extending horizontal stand plate 53 of the stand 51.
Each tool carrier 5A and 5B is connected releasably, by means of screws for example, to a fixing flange 6A or 6B, which is fixed on the end of a sliding rod 7A or 7B which, in turn, is guided and supported axially on the holding plate 42A or 42B by an axial bearing 8A or 8B. At the end remote from the fixing flange 6A and 6B, a further fixing flange 9A and 9B is provided on each sliding rod 7A or 7B, said fixing flange, in turn, being releasably connected to an associated fixing flange 10A or 10B at the front end of a hydraulic drive piston 11A or 11B, once again by means of screws for example.
It would also be conceivable, in the case of certain sizes of machine, for the tool carriers 5A and 5B to be screwed directly to the fixing flanges 10A and 10B and to dispense completely with the guide system with the holding plates 42A and 42B.
The hydraulic drive piston 11A or 11B can be moved and is guided axially with respect to the axis B in an associated hydraulic chamber 13A or 13B. A piston component 12A or 12B divides a front subchamber 15A or 15B from a rear subchamber 14A or 14B of the hydraulic chamber 13A or 13B and is guided in a sealed manner against the inner wall of the hydraulic chamber 13A or 13B. During a forward motion of the drive piston 11A or 11B along the axis B in the direction of the approach motion R, the rear subchamber 14A or 14B increases in size, and the front subchamber 15A or 15B decreases in size, and the situation is reversed during the return motion, which is directed counter to the approach motion R.
The position of the drive piston 11A or 11B within the hydraulic chamber 13A or 13B can be measured by means of an associated position measuring device 21A or 21B and can thus be used as a parameter for monitoring or controlling the forming process.
The front subchamber 15A or 15B is sealed off from the outer surface of the drive piston 11A or 11B by a seal 28A or 28B, wherein it is also possible for the seal 28A or 28B additionally to have the function of a bearing for the drive piston 11A or 11B. In general, the seal does not assume the sealing function. For this purpose, either an additional guide strip made of plastic or a guide bushing, made of bronze for example, is used, and this can also accommodate the seal, for example.
The rear subchamber 14A or 14B is in fluid communication with an associated stroke chamber 17A or 17B via a rear connecting duct 24A or 24B. The front subchamber 15A or 15B of the hydraulic chamber 13A or 13B is in fluid communication with an intermediate chamber 26A or 26B via a front connecting duct 25A or 25B, said chamber in turn being in fluid communication with a compensation tank or pressure accumulator 75A or 75B.
Subchambers 14A and 14B and subchambers 15A and 15B of the hydraulic chambers 13A and 13B, the stroke chambers 17A and 17B and intermediate chambers 26A and 26B, and connecting ducts 24A and 24B and connecting ducts 25A and 25B are all filled with a hydraulic medium, in particular a hydraulic oil or some other well suited pressure-resistant and virtually incompressible hydraulic medium.
Moving in each stroke chamber 17A or 17B is an associated reciprocating piston 18A or 18B, which is coupled by a joint 20A or 20B to one end of a reciprocating rod 19A or 19B as a transmission element. The reciprocating rod 19A or 19B is coupled at the other end to an eccentric element 22A or 22B.
The eccentric element 22A or 22B is arranged for conjoint rotation on an associated rotary shaft 23A or 23B and is supported eccentrically with respect to an axis of rotation E of the rotary shaft 23A or 23B. An eccentric axis F or G of the eccentric element 22A or 22B is spaced apart from the axis of rotation E by an appropriate eccentric distance hA or hB, resulting in a corresponding maximum stroke of 2·hA or 2·hB of the reciprocating piston 18A or 188 coupled to the eccentric element 22A or 22B by the reciprocating rod 19A or 19B during one complete revolution of the eccentric element 22A or 22B. The reciprocating motion of the reciprocating piston 18A or 18B takes place in a linear manner along a stroke axis C or D, which is perpendicular to the axis of rotation E and the eccentric axes F and G.
In the illustrative embodiment shown, the axes of rotation of the two rotary shafts 23A and 23B coincide on a common axis of rotation E, even though this is not necessarily the case. Moreover, the two rotary shafts 23A and 23B are driven by a common central rotary shaft 30 via respective couplings 33A and 33B, preferably in synchronism. Rotary shaft 30 likewise rotates about the common axis of rotation E and is driven by a central rotary drive 50, which is arranged on and/or in a housing 32 which, in turn, is supported and arranged on the stand plate 53. Rotary shaft 30 is supported within the housing 32 in a rotary bearing 31 designed as a transmission hollow shaft. The rotary drive 50 comprises an electric drive motor 58, which, in particular, can be a servomotor or permanent magnet motor and/or torque motor or asynchronous motor, and a transmission, which is arranged in the housing 32 and by means of which the drive motor 58 drives rotary shaft 30. By virtue of this arrangement, the two rotary shafts 23A and 23B and hence the eccentric elements 22A and 22B and, finally, the reciprocating pistons 18A and 18B move in synchronism with respect to one another, this in turn having the effect that both drive, pistons 11A and 11B move simultaneously forward in the approach motion R or rearward in the return motion owing to the hydraulic coupling with the reciprocating pistons 18A and 18B, that is to say the two tools 4A and 4B are fed simultaneously toward the workpiece 2 or retracted simultaneously from the workpiece 2. It would also be conceivable to design the entire rotary drive 50, together with the drive motor 58 and the transmission 32, as an “underfloor drive” and to arrange these units together with the eccentric elements 22A and 22B below the axis B.
The volumes of the stroke chambers 17A and 17B and of the rear subchambers 14A and 14B of the hydraulic chambers 13A and 13B are matched to one another, with the result that the stroke 2·hA or 2·hB of the reciprocating piston 18A or 18B preferably corresponds to the total stroke or total deflection of the drive piston 11A or 11B and hence of the tools 4A and 4B in the working motion.
The rear subchambers 14A and 14B of the hydraulic chambers 13A and 13B are furthermore connected to a hydraulic pump 64A or 64B by a respective port 34A or 34B and an associated hydraulic connection 44A or 44B. The hydraulic pumps 64A and 64B are, in particular, hydraulic servopumps, e.g. axial piston pumps, driven by position-controlled servomotors 54A and 54B, which hold the pump rotors or pistons firmly in position, having a hydraulic compensation reservoir. The hydraulic pump 64A or 64B serves, on the one hand, to fill the rear subchamber 14A or 14B with the hydraulic medium and, on the other hand, for fixing the axial end position of the drive piston 11A or 11B in the hydraulic chamber 13A or 13B and hence also the position of the tools 4A and 4B. If the hydraulic pumps 64A or 64B keep or introduce more hydraulic medium in or into the associated rear subchamber 14A or 14B by building up a corresponding hydraulic pressure, the end position of the drive piston 11A or 11B shifts forward and vice versa.
Finally, a further hydraulic pump 65 is provided, which is connected to a hydraulic connection 45, in which a pressure measuring device 56 is arranged and which divides into two parallel branches 45A and 45B, each of the two branches 45A and 45B being connected to one of the intermediate chambers 26A or 26B. The hydraulic pump 65 is thus also coupled hydraulically to the front subchamber 15A or 15B of the hydraulic chamber 13A or 13B and preferably serves as a reset device for exerting a resetting force on the associated drive piston (11A, 11B) by virtue of the hydraulic pressure in the front subchamber 15A or 15B, and thus in practice sets the preload on the drive piston 11A or 11B. Instead of such a hydraulic reset device, it would also be possible to provide a purely mechanical reset device, e.g. a spring or the like.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2009 048 428 | Oct 2009 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2010/064785 | 10/5/2010 | WO | 00 | 5/16/2012 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2011/042408 | 4/14/2011 | WO | A |
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| 3645126 | Kralowetz et al. | Feb 1972 | A |
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| 3888104 | Ribback | Jun 1975 | A |
| 5379628 | Pahnke et al. | Jan 1995 | A |
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| 23 45 527 | Mar 1975 | DE |
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| 1456888 | Nov 1976 | GB |
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| Entry |
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| Intl Search Rpt (English), Jan. 17, 2011. |
| PCT Int'l Preliminary Re-port on Patentability, Apr. 11, 2012, Langenstein & Schemann GmbH. |
| Number | Date | Country | |
|---|---|---|---|
| 20120266642 A1 | Oct 2012 | US |
