Abstract
An apparatus for forging a hollow body from a pre-perforated hollow block includes forging tools that can be driven radially in relation to a forging axis, a clamping head which is displaceable on a guide bed in the direction of the forging axis and includes collet chucks for the hollow block, and a mandrel carriage which is arranged on the side of the clamping head facing away from forging tools, which is displaceable independently of the clamping head along the guide bed, and whose mandrel bar provided with the forging mandrel penetrates the clamping head coaxially to the forging axis. In order to provide advantageous constructional conditions the mandrel carriage includes an axial actuating drive for the mandrel bar and can be coupled in a tension-proof manner to the clamping head.
Claims
1. An apparatus for forging a hollow body from a pre-perforated hollow block, comprising a guide bed, a mandrel bar provided with a forging mandrel, forging tools that are driven radially in relation to a forging axis, a clamping head mounted on the guide bed for displacement in the direction of the forging axis and comprising collet chucks for the hollow block on a first side of the clamping head, and a mandrel carriage which is arranged on a second side of the clamping head opposite to the first side, wherein the mandrel carriage is displaceable independently of said clamping head along the guide bed, and wherein the mandrel bar provided with the forging mandrel penetrates the clamping head coaxially to the forging axis, wherein the mandrel carriage comprises an axial actuating drive for the mandrel bar and is coupled to the clamping head in a manner ensuring tensile strength.
2. The apparatus according to claim 1, wherein the mandrel carriage comprises a rotary drive for the mandrel bar.
3. The apparatus according to claim 2, wherein a control device is provided for triggering the axial actuating drive and/or the rotary drive for the mandrel bar depending on the temperature of the forging mandrel.
4. The apparatus according to claim 1, wherein the forging mandrel has a minimum length corresponding to an actuating distance of the axial actuating drive.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The subject matter of the invention is shown in the drawings by way of example, wherein:
(2) FIGS. 1 to 4 show an apparatus in accordance with the invention for forging a hollow body in different working positions in a simplified, purely schematic longitudinal sectional view;
(3) FIG. 5 shows the position of the apparatus for exchanging a mandrel bar;
(4) FIG. 6 shows the clamping head and the mandrel carriage in the coupling position on an enlarged scale, and
(5) FIG. 7 and FIG. 8 show two different working positions for the clamping head coupled to the mandrel carriage.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
(6) The illustrated apparatus for forging a hollow body from a pre-perforated hollow block 1 comprises forging tools 2 which can be driven radially in relation to a forging axis and which are provided upstream with a clamping head 3 and a mandrel carriage 4. The clamping head 3 and the mandrel carriage 4 are displaceably mounted on a common guide bed 5 and can be displaced independently from each other via travel drives 6 and 7 along the common guide bed 5. The travel drives 6, 7 may comprise drive pinions which engage in a toothed rack 8 for example.
(7) The mandrel carriage 4 is provided with a mandrel bar receptacle 9, which can be displaced axially by means of an actuating drive 10. Actuating cylinders 11 are indicated as the actuating drive 10. In order to allow the mandrel bar 12 with the forging mandrel 13 to be displaced axially not only in relation to the mandrel carriage 4 but also to enable rotation about the mandrel axis in rotary steps, the mandrel bar receptacle 9 which is respectively rotatably mounted is connected to a rotary drive 14.
(8) The clamping head 3 is penetrated by the mandrel bar 12 in a guide opening 15, wherein the forging mandrel 13 protrudes axially beyond the clamping head 3 and extends coaxially to the collet chucks 16 of the clamping head 3, by means of which the hollow block 1 to be forged is chucked in a manner suitable for forging. The preperforated hollow block can be provided with a configuration that is closed off in the region of one end. It needs to be clamped in the region of its open end however.
(9) As is shown in FIG. 1, the clamping head 3 and the mandrel carriage 4, which is provided for clamping the pre-perforated hollow block 1 held in a loading position coaxial to the forging axis, are displaced against the forging tools 2, wherein the forging mandrel 13 is inserted into the opening of the hollow block 1 and the collet chucks 16 grip the hollow block, as is shown in FIG. 2. The hollow block 1 which is clamped in this manner can now be displaced to a forging position according to FIG. 3, in which the forging mandrel 13 is advanced by means of the mandrel carriage 4 between the forging tools 3 through the hollow block 1, as shown in FIG. 3. In this displacement position, the mandrel carriage 4 is locked to the guide bed 5 via a locking device 17. The hollow block 1 can thus be subjected to a respective forward feed by the clamping head 3 for forging via the forging mandrel 13, wherein the axial forward feed via the travel drive 6 can be superimposed by a rotary forward feed via the respectively driveable collet chucks 16. During the forging process, the axial actuating drive 10 for the mandrel bar 12 can be actuated via a control device, so that the forging mandrel 13 is displaced in the axial direction in relation to the forging tools 2. Said axial displacement of the forging mandrel 13 can be used to forge a hollow body which is offset with respect to its inside diameter when the forging mandrel 13 comprises respectively offset diameter regions. The displacement of the forging mandrel 13 in relation to the forging tools 2 can also be advantageously used to reduce the temperature load on the forging mandrel 13 because the axial displacement of the forging mandrel 13 allows a distribution of the heat quantity over the length of the mandrel which is transmitted during the loading by forging via the forging tools. Advantageous constructional conditions are obtained in this connection when the mandrel length corresponds at least to the actuating distance of the axial actuating drive.
(10) FIG. 4 shows the end of the forging process. The hollow body 18 forged from the pre-perforated hollow block 1 is released in the conventional manner by the collet chucks 16 of the clamping head 3 in order to pull it from the opposite end between the forging tools 2 for forging the end of the hollow body. The illustration shows that the forging mandrel 13 was displaced accordingly via the axial actuating drive 10 of the mandrel carriage 4 in relation to its initial position according to FIG. 3.
(11) FIG. 5 shows the position of the apparatus for exchanging the mandrel. The forging mandrel 13 with the mandrel bar 12 is pulled from the side of the collet chucks 16 out of the mandrel bar receptacle 9 of the mandrel carriage 4 through the guide opening 15 out of the clamping head 3, which is displaced for this purpose together with the mandrel carriage 4 to the end of the guide bed 5 facing away from the forging tools 2. The forging mandrel 13 which is released in this manner can thus be changed together with the mandrel bar 12 and a new forging mandrel with a mandrel bar 12 can be inserted in the reverse direction through the guide opening 15 of the clamping head 3 into the mandrel bar receptacle 9 of the mandrel carriage 4.
(12) As is shown in FIG. 6, the clamping head 3 and the mandrel carriage 4 can be locked together in a tension-proof manner by means of a coupling device 19. Locking can occur by locks 20 which releasably engage into radial lock recesses 21, so that the clamping head 3 with the mandrel carriage 4 is connected mechanically into a modular unit which absorbs the axial forces occurring between the collet chucks 16 and the forging mandrel 13 without loading the guide bed 5. In the coupling position according to FIG. 6, hollow bodies can be forged in which high deformation forces are necessary. FIGS. 7 and 8 show the forging of a hollow body from a preperforated hollow block 1 that is difficult to deform for example, wherein the modular unit formed by the clamping head 3 and the mandrel carriage 4 is displaced against the forging tools 2 via the travel drive 6 of the clamping head 3. The forging mandrel 13 therefore requires a length corresponding to the length of the hollow block 1 when the forging mandrel is not displaced by the actuating drive in opposite direction to the forging forward feed of the hollow block. In the case of short hollow blocks 1, it may be advantageous under certain circumstances that the forging mandrel 13 is displaced in addition in the forward feed direction of the clamping head 3, which requires lengthening of the forging mandrel 13. FIG. 8 shows the position in which the clamping head 3 needs to release the hollow block 1 in order to enable completing the forging of the hollow block 1.
