JP2000351041A - Method and device for deforming - Google Patents

Abstract

PROBLEM TO BE SOLVED: To endure a tool for higher deformation working force as well as to have a simple and hard to fail structure. SOLUTION: A work is subjected to deformation working by a deformation working tool, consisting of an upper ram supporting a punch 2, an ejector 3 and an outside tool encircled with a bell shaped fastening member 7 and so that at each press stroke, the bell shaped fastening member 7 applies pre-stress to a die 5 through a conical face with the variable force from outside. In a method to advantageously perform flow extruding, imparting pre-stress for the die 5 by the bell shaped fastening member 7 is performed before or during flow extruding, further, pre-stress is again released before ejection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises an upper ram for supporting a punch, a lower ram or ejector, and an outer tool having a die surrounded by a bell-shaped clamping member. The workpiece is deformed (Um) with a deforming tool in which the member preloads the die via a conical surface with a variable force from the outside during each press stroke, and thus applies prestress or prestress.
forming, preferably flow extrusion (Fli)
espressen).

[0002] The invention further relates to an apparatus for implementing such a method.

[0003]

2. Description of the Related Art When a workpiece is deformed in a closed forging tool or a flow extrusion tool, a prestress or prestress is applied to a die by various means.
It is known to influence the inner contour of the die and to cause a reduction in operating load due to the superposition of compressive stress.

[0004] DE-A 19 52
In the deforming tool disclosed in US Pat. No. 3691, preferably a forging die for hot or warm deformation, a variable external force is applied to the die during each press stroke via a conical surface. Prestress or prestress is applied.
However, in this known tool, since the prestressing is performed by expanding the die, a tensile stress is introduced into the die, which causes a disadvantage that the service life of the die is reduced. Further, the structure is extremely complicated, which is disadvantageous. Because, until the work is pushed out,
This is because the holding device holds the spread tool in an open state. Such tools are not particularly suitable for flow extrusion. This is because such a tool cannot absorb a high deformation processing force generated during flow extrusion.

[0005]

An object of the present invention is to provide a method as described at the outset in which the tool has a structure which is able to withstand higher deformation forces and which is simple and hard to break down. Can be improved.

It is a further object of the present invention to provide an apparatus suitable for performing such a method.

[0007]

SUMMARY OF THE INVENTION In order to solve this problem, the method of the present invention pre-stresses the die by means of a bell-shaped clamping member before or during flow extrusion and pre-stresses before extrusion. Was canceled again.

[0008]

The advantages obtained according to the invention are, in particular, the fact that the tool life is significantly increased. This is because the tendency to wear and fatigue fracture is reduced. In addition, it is advantageous that the finished workpiece is prevented from being very strongly clamped by the springback die after the punch has been withdrawn. This significantly reduces the force to be applied by the knockout or ejector. Furthermore, better parallelism of the outer contour is achieved, especially for long finished parts. In a conventional deformation processing method using a conventional apparatus, an internal stress introduced into a die during the deformation processing is reduced through a protruding path of a finished part. This means that the mold shrinks via the projecting path of the finished workpiece, thereby causing the outer contour of the workpiece to be conically deformed.

The advantage of reducing the clamping force at the die after the deformation and thus the required ejector ejection force required is that workpieces with a helically twisted outer profile, for example bevel teeth, are provided. It has a particularly advantageous effect on pinions. Thereby, the quality of the tooth flank in the projecting direction is improved as compared with the conventional cold flow extrusion.

Advantageous refinements of the method according to the invention are described in claims 2 and 3.

That is, in the method according to the second aspect, the prestressing of the die is performed while increasing the tightening force during the flow extrusion. In the method according to the third aspect, the stress release to the die is performed only until an adjustable residual prestress remains.

The solution according to the invention and the advantageous configuration for forming an apparatus for carrying out the method according to claims 1 to 3 are specified in claims 4 to 7.

In a first embodiment of the device according to the invention, the bell-shaped clamping element is adapted to be pushed down by the upper ram. In this case, it is advantageous if a hydraulic or mechanical holding cushion is arranged between the upper ram and the bell-shaped clamping element.

In a second embodiment of the device according to the invention, the bell-shaped tightening element is depressed by a separate hydraulically loaded auxiliary unit.

In a third embodiment of the device according to the invention, the movement of the bell-shaped clamping element is limited by one or more, preferably adjustable, stops.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

The flow extrusion tool is formed on a press table 1 as shown in FIG. The ram with the associated punch 2 and the knockout or ejector 3 are only shown schematically. A blank 6 is located in the mold opening 4 of the die 5. The die 5 is formed in a conical shape on the outer peripheral surface over at least a part of its height. A bell-shaped tightening member 7 having an inner conicity corresponding to the conicality of the die 5 surrounds the die 5 movably in the axial direction.

The bell-shaped clamping element 7 is held and guided by a support structure. The bell-shaped tightening member 7 is formed by the stopper 8.
Is limited in axial movement. In order to adjust and adjust the tightening of the die 5 by the bell-shaped tightening member 7, the stopper 8 is axially adjustable. By appropriate adjustment of the upper stopper 8, the die 5 is moved via the bell-shaped tightening member 7
It is possible to achieve a constant retention of the compressive intrinsic stress as a residual prestress even if it is reduced. This reduces the prestress amplitude, which leads to a further increase in service life.
The drive link mechanism 9 for axially moving the bell-shaped tightening member 7 is also only schematically illustrated. The axial movement of the bell-shaped tightening member 7 can be performed through any means. For this purpose, the bell-shaped clamping element 7 can be driven indirectly by a ram via a hydraulic or mechanical holding cushion. However, the bell-shaped tightening member 7
It is also conceivable to exercise the motor via a separate, for example hydraulically loaded auxiliary unit. The conical apex angle formed between the bell-shaped tightening member 7 and the die 5 is advantageously formed such that no self-locking action occurs. This eliminates the need for applying a particularly high force to release the bell-shaped tightening member 7.

FIGS. 2 to 5 show the individual tightening and working steps. In the state shown in FIG. 1, the die 5 is not loaded. The bell-shaped clamping member 7 does not introduce any additional compressive stress on the die 5. The blank 6 is located in the die opening 4 of the die 5.

In FIG. 2, a bell-shaped tightening member 7 is axially placed on the cone of the die 5 to apply a preload (preload) to the die 5 from the outside in the radial direction, thereby applying prestress or prestress. Is shown.

After the die 5 has thus been loaded with additional compressive stress in the radial direction, the actual deformation process takes place, as shown in FIG. At this time, the punch 2 runs into the mold opening 4 of the die 5 and deforms the blank 6 to form a finished part 10.

The two working steps described above, namely the axial movement of the bell-shaped clamping element 7 and thus the introduction of compressive stress on the die 5 and the formation of the finished part 10 by deformation of the blank 6 can also be combined with one another. it can. This is advantageously possible, in particular, when the force load of the bell-shaped clamping element 7 is applied in relation to the deforming force of the ram. If such a combination of the two working steps "deformation" and "prestressing the die 5" is performed, a further improved service life of the die 5 is obtained. This is because, in that case, the die 5 retains a substantially constant and constant internal stress during the deformation process. The compressive stress in the die 5 additionally introduced by external pressing is almost offset by the tensile stress introduced during the deformation processing. As a result, the periodic operating load can be reduced to zero.

FIG. 4 shows a state in which the tool is released. Preferably, at the same time as the punch 2 is withdrawn, the bell-shaped clamping element 7 is also released.

FIG. 5 shows an operation process when the completed part 10 is ejected.

FIG. 6 schematically shows the structure of the die 5. The die 5 is advantageously formed from two parts. The die base 11 supports, in the center, a die insert 12 made of a high-strength material. The die base part 11 and the die insert 12 are advantageously connected to one another by a press fit.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a flow extrusion tool.

FIG. 2 is a cross-sectional view showing one step of a work process of the flow extrusion tool shown in FIG.

FIG. 3 is a sectional view showing another step of the working process of the flow extrusion working tool shown in FIG. 1;

4 is a sectional view showing still another step of the working process of the flow extrusion working tool shown in FIG. 1. FIG.

FIG. 5 is a sectional view showing yet another step of the working process of the flow extrusion working tool shown in FIG. 1;

FIG. 6 is a sectional view showing a detailed structure of a die.

[Explanation of symbols]

1 press table, 2 punch, 3 ejector, 4 type opening, 5 die, 6 blank, 7
Bell-shaped tightening member, 8 stopper, 9 drive link mechanism, 10 completed part, 11 die basic part, 12
Die insert

Continued on the front page (72) Inventor Mattias Hansel Liechtenstein Nendern-sur-Strasse 244

Claims (7)

[Claims] 1. An upper ram for supporting a punch (2);
Consisting of a lower ram or ejector (3) and an outer tool having a die (5) surrounded by a bell-shaped clamp (7), the bell-shaped clamp (7) being external during each press stroke. Via a conical surface with variable force from the die (5)
A method for deforming, preferably flow extruding, a workpiece with a deforming tool adapted to pre-stress a die (5) with a bell-shaped clamping member (7).
Pre-stressing before or during flow extrusion and re-releasing the pre-stress prior to overhang. 2. The method according to claim 1, wherein the prestressing of the die is carried out during the flow extrusion with increasing tightening forces. 3. The method according to claim 1, wherein the de-stressing of the die is effected only until an adjustable residual prestress remains. 4. A device for carrying out the method according to claim 1, wherein the bell-shaped tightening member is pushed down by an upper ram. An apparatus for deformation processing, characterized in that: 5. The device according to claim 4, wherein a hydraulic or mechanical holding cushion is arranged between the upper ram and the bell-shaped clamping element. 6. A device for carrying out the method according to claim 1, wherein the bell-shaped clamping element is depressed by a separate hydraulically loaded auxiliary unit. An apparatus for deforming, characterized in that: 7. A device for carrying out the method according to claim 3, wherein the movement of the bell-shaped clamping element (7) is limited by one or more, preferably adjustable, stops (8). An apparatus for deformation processing, characterized in that: