HK1139358A - Method for producing workpieces - Google Patents

Description

Method for producing a workpiece

Technical Field

The invention relates to a method for producing a workpiece according to the preamble of claim 1.

Background

A method according to the preamble of claim 1 is known from DE 102005057945 a 1. In a corresponding method, rotationally symmetrical preforms are processed, mainly by means of pressure rollers, in order to produce, for example, support rollers, automobile parts or gas cylinders. In terms of the loading of such products, it is desirable to reinforce certain regions already during the deformation process. When using corresponding products, the central region is mainly subjected to a high load, so that a material reinforcement in this region is preferred. Particularly preferred here are shaped parts with concave or conical inner surfaces, which cannot be produced by the hitherto known rolling methods.

Disclosure of Invention

It is therefore an object of the present invention to provide a method of the type mentioned at the outset, with which workpieces having a concave or conical inner surface can be produced from a preform.

This object is achieved by a method having the features of claim 1 or by a roller press having the features of claim 10. Advantageous embodiments are given in the dependent claims.

According to a first embodiment of the invention, a preform, preferably a cylindrical tube, is clamped onto the spindles of the headstock and tailstock. The headstock and the tailstock each have a tool housing, which is arranged concentrically around the respective spindle and serves for centering the preform from the outside. The spindle and the tool housing are movable parallel to the machine axis or the preform longitudinal axis, respectively. The mandrels have respective outer surfaces which are reduced in one direction, that is, such that they form the negative of the concave or cylindrical inner surface to be formed in the preform. According to the invention, the outer surface of the preform is now pressed by one or preferably several press rollers. During machining, the sides of the two mandrels facing each other are held in contact with each other. In this case, the spindle and the tool housing are moved in such a way that, firstly, a material flow of the preform material enters the intermediate space between the tailstock spindle and the associated tool housing. The headstock and the tool housing of the associated spindle are then moved such that the material flow is directed substantially toward the headstock into the region of the outer surface of the associated spindle and thus completes the workpiece with a concave or conical inner surface.

Drawings

The invention is explained in more detail below schematically with reference to the figures.

Fig. 1 shows a longitudinal section through a roller press designed for carrying out the method according to the invention, in which the preform is clamped and before the mandrel is closed,

fig. 2 shows the machine of fig. 1, wherein the preform is clamped and before the mandrels are closed,

figure 3 shows the machine of figure 1 before processing of the preform according to the invention,

figure 4 shows the deformation after deformation of a portion of the preform,

figure 5 shows the deformation near the end of the preform deformation,

figure 6 shows the machine after removal of the finished workpiece,

fig. 7 shows a further embodiment according to the invention in a longitudinal section through a roller press which is designed for carrying out the method according to the invention, wherein the preform is clamped and, before the mandrel is closed,

fig. 8 shows the machine of fig. 7, with the preform clamped and before the mandrel is closed,

figure 9 shows the machine of figure 7 before processing of the preform according to the invention,

figure 10 shows the deformation after deformation of a portion of the preform,

figure 11 shows the deformation near the end of preform deformation,

figure 12 shows the machine after removal of the finished workpiece,

fig. 13 shows a third embodiment of the roller press according to the invention in longitudinal section, which is designed for producing bottles with expanding mandrels, wherein before the clamping of the preform,

fig. 14 shows the machine of fig. 13, with the preform clamped,

fig. 15 shows the machine in fig. 13, in a deformed condition after deformation of a portion of the preform,

figure 16 shows the deformation near the end of preform deformation,

fig. 17 shows the machine when the finished workpiece is removed.

Detailed Description

Fig. 1 to 6 show a schematically depicted roller press with which the method according to the invention can be carried out.

The device shown in fig. 1 has a spindle head 1 and an associated tool housing 6, in which a spindle 4 is guided in an axially displaceable manner. The tool housing 6 and the spindle 4 lie on a common longitudinal axis MA extending through the centers of the spindle S1 and the tailstock spindle S2. Hydraulic cylinder H1 enables axial movement of spindle 4 relative to tool housing 6. The mandrel 4 as well as the mandrel 3 are equipped with a negative shape (negativeform) of the inner surface 8.2a and 8.2b of the finished piece, respectively. The smallest diameter is in the plane of the end faces 3c and 4c of the mandrels 3 and 4 facing each other.

The tool housing 6 has a receiving bore 6b with a driver 6a in relation to the spindle mounting. The receiving bore 6b has an outer diameter of the preform 8, so that the preform 8 can be received by the receiving bore 6b in a centered manner relative to the longitudinal axis MA. When the preform 8 is inserted (fig. 1), the driver 6a serves firstly as an axial positioning structure for the preform 8. If the preform 8 is pressed against the mandrel 3 of the tailstock in the initial phase of the deformation, the driver 6a drives the preform via the tool housing 6 when the spindle S1 rotates. During the deformation, the axial compression of the preform is undertaken by the axial deformation force of the pressure roller 7.

Depending on the size of the preform 8 to be deformed, the tailstock 2 with the tailstock spindle S2 and the tool housing 5 can also be equipped with a drive which runs synchronously with the spindle S1. The tailstock spindle and the tool housing 5 are centered on and rotate about a common longitudinal axis MA.

The spindle 3 in the tool housing 5 is axially displaceably arranged by means of a hydraulic cylinder H2.

Depending on the type of roller press, the headstock 1 and tailstock 2 can be moved relative to each other and independently of each other towards the axially positioned press rolls 7. As an alternative to this, there is a design solution in which the pressure rollers 7 are arranged displaceably, jointly by axial feed, wherein the headstock 1 is arranged fixedly and the tailstock 2 is arranged displaceably. The latter solution is shown in fig. 1 to 6.

The mandrel 3 has an axial stop face 3d and an outer diameter 3e in the direction of the negative shape which corresponds to the inner diameter of the preform 8. If a preform 8 is received, the mandrel 3 is advanced into the preform 8 by the feed of the hydraulic cylinder H2, the side of the preform 8 facing the mandrel 3 is centered with an outer diameter 3e and pushed into the previously described outer centering structure 6b of the tool mounting part 6, in order to press it with axial pressure against the driver 6 a. At this stage of the working process (fig. 2), the preforms are held centered by hand or by means of an automatic loading device until clamping is ensured.

As shown in fig. 1 to 6, the tool housing 5 is only required when the tailstock main shaft S2 is driven. If the tailstock main shaft is not driven, the spindle 3 takes on the function of tailstock centre with the hydraulic cylinder H2. A corresponding embodiment is shown in fig. 7 to 12.

After the preform 8 has been clamped (fig. 2), the spindle 4 is moved axially forward towards the tailstock 2 by the feed of the hydraulic cylinder H1 so as to form a unit with the spindle 3. Here, the two side faces 3c and 4c of the spindles 3 and 4 are pressed against each other, with the centering projections 3a of the spindle 3 inserted into the centering holes 4a of the spindle 4. The negative shape of the inner surface of the finished part is thus formed by the two mandrels 3 and 4. The length of the two partial negative shapes 3b, 4b together is equal to the length of the finished part formed from the preform 8. If a cylindrical profile 8c with the diameter of the dividing plane 3a or 4c is provided between the partially negative shape 3b, 4b and the dividing plane 3c and/or the dividing plane 4c, the length of the finished part is increased by this value.

The same applies to the case where a cylindrical shaped portion 8c is provided in the region of the preform toward the spindle side, as shown in the figure. Alternatively, an additional cylindrical profile 8c can also be formed toward the rear seat side.

The pressure roller 7 is moved radially outside the clamped preform 8 into its position in order then to be moved jointly in the axial direction against the rotating preform 8 (fig. 3). The rotation of the preform 8, the tool housing 5, 6 together with the spindle 3, 4, the spindle S1 and the tailstock spindle S2 is effected by the drive of the spindle S1 and, depending on the embodiment, also by the synchronously operating drive of the tailstock spindle S2.

According to the invention, one or preferably several pressure rollers 7 are arranged on the circumference of the preform 8 for the deformation. The press rolls 7 are provided with lead-in inclined portions in the axial direction on the circumference. The pressure roller 7 is located radially in a position towards the outer diameter of the finished part 8.2, which is to be obtained by rolling the preform 8. If the pressure rollers 7, which are positioned centrally about the longitudinal axis MA of the main shaft S1, are jointly moved in the axial direction x by a joint feed onto the rotating preform 8, they rotate by contact with the preform 8. The material is brought into a flowing state in the region between the pressure roller 7 and the relevant axial cross section of the mandrel 3 (fig. 4) by the axial and radial pressure of the pressure roller 7. The material is squeezed into the free space 9 existing between the mandrel 3 and the pressure roller 7 so as to be offset towards the tailstock 2 after filling the volume of the free space 9 (fig. 5) to complete the adjusted outer diameter of the piece 8.2 and the inner diameter given by the mandrel 3. By means of an axial stop 3d on the mandrel 3 of the tailstock 2, this mandrel 3 is entrained by the material flowing back, as long as the material flows back by extrusion. The error in the diameter of the preform 8 is therefore only visible in terms of the length of the deformed workpiece 8.2.

Since the two spindles 3, 4 are jointly connected, they are jointly pushed by the extruded material towards the tailstock 2, while the pressure roller 7 jointly moves towards the headstock 1. Here, a finished part 8.2 is formed from the preform 8 by material extrusion, the outer diameter of which is reduced relative to the preform 8, duplicating the two mandrels 3, 4 as the inner diameter.

The deformation ends when the pressure roller 7 comes near the outer centring feature 6b of the preform (figure 5). Thereafter, the respective press rolls 7 are returned to their initial positions in the radial direction and are collectively moved to their initial positions in the axial direction. The spindle 4 on the spindle side is disengaged and pulled back, and the mandrel 3 on the tailstock side is likewise disengaged from the formed workpiece 8.2. For this purpose, if necessary, a discharger is provided which acts from the outside. With the tailstock 2 being pulled back, the shaped piece 8.2 is released (fig. 6).

The shaped workpiece 8.2 is characterized by a reduced outer diameter and in terms of inner diameter by a profile which reproduces the two mandrels 3, 4.

In the method according to the invention, concave, conical and cylindrical profiles are used on the mandrel. Since the mandrel or the combination of the two mandrels is displaced during the deformation in which the material flows by material overflow, which is formed by the reduction of the preform cross-section to that of the finished shape, no relative movement is produced between the inner surface of the workpiece and the mandrel.

The mandrel is moved axially in the direction of the degree of freedom only when there is material overflow. That is to say, the deformed material rolls axially onto the mandrel and only continues to push the mandrel when there is sufficient material present there. No relative movement is thus produced between the mandrel and the material, but only rolling in the axial direction following the contour. Said rolling of the material in the region of the press rolls can be supported or also made difficult by the hydraulic pressure regulation in the cylinders H1 and H2.

It is also not possible by rolling of the material that so-called seizure between the two elements, i.e. the material and the outer surface of the mandrel, occurs during deformation.

Errors in the preform region are absorbed by the extruded material without affecting the properties of the finished workpiece, i.e. the different wall thicknesses of the preforms do not affect the wall thickness of the finished workpiece formed by the press roller; the material flow continues only when a given wall thickness of the finished workpiece is reached in the relevant axial plane. Therefore, mainly only the length of the formed workpiece is related to the error. The material flow rate resulting from the cross-sectional reduction in the relevant axial plane of the preform (to the cross-section of the relevant axial plane of the finished part) is formed by the material excess and the feed rate of the pressure roller. I.e. the axial movement speed of the unit consisting of two mandrels is correlated to the reduction of the cross section in the respective axial plane of the preform, while the feed speed of the pressure rollers remains the same.

In this way, different steps, steps and contours can be formed into the inner surface of the rotationally symmetrical hollow body by the method, if the steps, steps and contours are reduced in diameter toward the boundary of the closed mandrel.

This also applies to the case of machining with only spindles on the tailstock side. Furthermore, the method can be applied when only a part of the rotationally symmetrical body is deformed in the longitudinal direction in the case of using one or two spindles and is applied here.

It is thus possible to shape the so-called support part on two supports having the same resistance torque as a function of the subsequent load of the workpiece.

The properties of the workpiece produced from the cylindrical preform according to the method are particularly suitable for gas cylinders and support rollers.

Fig. 7 to 12 show a second embodiment of the roller press according to the invention. The roller press differs from the device in fig. 1 to 6 only in that the tailstock side 2' has the above-mentioned function of a tailstock center, wherein no tool housing is provided on the tailstock side and only the spindle 3 is mounted so as to be movable in the axial direction x via a hydraulic cylinder H2. During the deformation, the mandrel 3 is pushed back against the force of the hydraulic cylinder by the material flow towards the tailstock side 2'. Furthermore, the method is performed similarly to the method described above with reference to fig. 1 to 6.

An alternative variant is shown in fig. 13 to 17. In contrast to the embodiment described above, this device is sufficient with only one expansion mandrel 4' arranged on the side of the mandrel. This variant is used in particular for deforming a cylindrical preform 8 closed at one end, for example a gas cylinder.

The expanding mandrel 4 'has a section which corresponds approximately to the mandrel 4 of the above-described embodiment and has a conical or conical outer surface 4 b' and an adjacent expanding section 4d which has an outer surface section 4b ″ which can be adjusted relative to the machine axis MA via an expanding mechanism 4e so that it approximately assumes the shape of the mandrel 3 of the above-described embodiment.

The preform 8 is first pushed with its open side onto the expanding mandrel 4 ', wherein the slide 10 opposite the mandrel 4' acts on the closed end of the preform 8 and pushes it up to the stop 6a on the tool housing 6 of the headstock 1 (fig. 14). The slide 10 holds the preform 8 against the stop 6a so that the section 4f of the mandrel 4 ' can be expanded by means of the expansion mechanism 4e so that the above-mentioned free space 9, which corresponds to the negative shape of the inner surface to be shaped, is formed by the faces 4b ' and 4b "between the inner wall of the preform 8 and the mandrel 4 '. During the deformation by the pressing rollers, material is also extruded from the preform 8 into the intermediate cavity 9, the central axis 4' of which moves (fig. 15 and 16). After the deformation process has ended, the finished molded part 8.2 is removed after the mandrel 4' has been moved back (fig. 17), and the machining of the open end of the molded part 8.2 can be continued in order to produce, for example, a gas cylinder 8.3.

In the embodiment described, the deformation by the pressure rollers takes place in both directions, namely in the radial direction by reducing the outer diameter of the preform 8 and in the axial direction by shaping the cylindrical shape with a new, reduced outer diameter. Here, each press roller 7 moves forward toward the headstock 1 with the preform 8 rotating. This enables the material to be extruded helically and the extruded material is thus distributed not only axially but also (tangentially) in the circumferential direction of the mandrel 3, 4'. The reason for this is that the material is pressed from a larger diameter to a smaller diameter while the material is rotating.

The material flows radially to the smaller diameter of the mandrel 3, 4' and fills the cavity; tangential flow, extrusion by rolling caused by rotation while being fed in the axial direction; and axial flow against the feed motion if there is sufficient surplus of material.

If the spindle 3, 4 'is prevented from rotating radially in this case, the material must move relative to the spindle 3, 4' in the circumferential direction of the spindle. Thereby producing a relative movement of the shaped body with respect to the body of the preform 8 on the fixed mandrel.

According to a preferred embodiment, the spindles 3, 4' are freely movable in the circumferential and axial directions, whereby the spindles can be matched to their movement in both directions without hindrance by contact with the deformed material. The relative movement in the circumferential direction takes place in the region of the preforms 8 that is free from contact with the spindle-side mandrels 4, 4'.

List of reference numerals

1 main spindle box

2 tailstock

2' tip sleeve

3 tailstock mandrel

3a tenon

Surface of 3b tailstock mandrel

End side of 3c tailstock mandrel

3d stop

Centering diameter of 3e tailstock mandrel

4. 4' spindle

4a hole

4b, 4 b' surface of the spindle

4c end side of spindle

4d expansion segment

4e expansion mechanism

5 tailstock cutter shell

6 main shaft cutter shell

6a driving part

7 compression roller

8 preform

8.1 preforms to be machined

8.1a first region

8.1b transition region

8.1c third region

8.2 finished work

8.2a first region

8.2b second region

8.2c third region

9 cavity

10 sliding block

A longitudinal axis of preform or workpiece

Longitudinal axis of MA roller press

S1 Main shaft

S2 tailstock main shaft

Hydraulic cylinder of H1 main spindle box

Hydraulic cylinder of H2 tailstock

8.3 gas bomb

Claims (16)

1. Method for manufacturing a workpiece, wherein a substantially cylindrical preform (8) is deformed into a finished workpiece (8.2) by means of at least one pressing roller (7), wherein the following steps are performed:

a. pushing a section of the preform (8) onto at least one first mandrel (3, 4') which is movably supported parallel to the longitudinal axis (A) of the preform (8);

b. orienting the mandrel (3, 4 ') so that its surface (3b, 4 b; 4 b') in the preform (8) substantially forms the negative shape of the inner surface to be shaped on the preform (8);

c. performing a relative movement between the preform (8) and the pressure roller (7) in a direction parallel to the longitudinal axis (A) while the pressure roller (7) is pressed onto the preform (8);

the method is characterized in that: step c is performed such that the material of the preform (8) is extruded by the press roll (7) and thus the mandrel (3, 4') is pushed by the extruded material.

2. The method of claim 1, wherein: after step a, the other section of the preform (8) opposite the first section is pushed onto a second mandrel (4) which is movably supported parallel to the longitudinal axis (A) of the preform (8), and then the first mandrel (4) and the second mandrel (3) are closed, so that the surfaces (3b, 4b) of the first and second mandrels which are located inside the preform (8) substantially form the negative shape of the inner surface to be shaped on the preform (8).

3. The method of claim 2, wherein: the spindles (3, 4) are coupled during the pressing.

4. The method according to any of the preceding claims, characterized in that: the mandrels (3, 4, 4') are in each case temporarily pushed and/or rotated axially by the material flowing back from the preform (8).

5. The method of claim 4, wherein: the movement is effected towards a first tool housing (5) connected to the tailstock (2), in which a first spindle (3) is movably mounted.

6. The method according to any of the preceding claims, characterized in that: the preform (8) is pushed onto the first mandrel (3) by means of a driver (6a) located on the tool housing (5, 6).

7. The method of claim 6, wherein: the preform (8) is centred by means of a centring structure (3e) on the first mandrel (3) when pushed.

8. The method according to any of the preceding claims, characterized in that: at least one mandrel (3, 4) with a conical or biconical, conical or biconical outer surface (3b, 4b, 4 b') is used.

9. The method according to any of the preceding claims, characterized in that: only one section of the rotationally symmetrical preform (8) is deformed.

10. Roller press, in particular for carrying out a method according to one of the preceding claims, having at least one mandrel (3, 4, 4 ') which is movably supported parallel to the Machine Axis (MA) for pushing a preform (8) to be deformed and at least one deformation roller (7) for deforming the preform (8), wherein the outer surface of the at least one mandrel (3, 4, 4 ') is configured such that it has a reduced area in the region of the pushed preform (8), which reduced area essentially forms the negative shape of the inner surface to be formed on the preform (8), the at least one mandrel (3, 4, 4 ') being supported such that it is pushed and/or rotated by material extruded from the preform (8) by rolling when being deformed.

11. The roller press of claim 10, wherein: the roller press also has a spindle head (1) with a tool housing (6) and an associated further spindle (4) which is mounted so as to be movable parallel to the Machine Axis (MA).

12. The roller press of claim 11, wherein: a tailstock (2) is also provided with the associated spindle (3) which is movably supported parallel to the Machine Axis (MA), wherein the two spindles (3, 4) are arranged concentrically, and the two spindles (3, 4) face each other with the end sides (3c, 4c) thereof and are respectively reduced toward the end sides (3c, 4c) thereof.

13. The roller press of claim 12, wherein: a tool housing (5) is also provided, which is associated with the tailstock (2) and is mounted so as to be movable parallel to the Machine Axis (MA).

14. The roller press according to any one of claims 11 to 13, characterized in that: the one spindle (3) has a tenon (3a) which can be inserted into a hole (4a) provided in the other spindle (4) for centering the other spindle.

15. The roller press according to any one of claims 10 to 14, characterized in that: the at least one mandrel (3, 4, 4') has a centering structure for the preform (8) to be received.

16. The roller press according to any one of claims 10 to 15, characterized in that: the mandrel (4') is provided with expansion means.