EP1046440A1 - Forging method of axial symmetric metallic workpieces - Google Patents

Abstract

The lateral extrusion pressing of a partially-heated workpiece (100) gives an axially symmetrical distortion with increased shaping grades. The workpiece (100) is inserted into a lower die (20), to be pressed by an upper die (10) with a press force (F) The local heating is from the lateral extrusion pressing, with the heat effect (30) matched to the shape change behavior of the workpiece (100).

Description

The present invention relates to a method according to the preamble of claim 1.

Numerous forming processes are from process engineering known, this either on the warm or the cold Workpiece. Notoriously known is the extrusion according to the preamble of claim 1.

The well-known solid formations come across in cross extrusion quickly at room temperature below room temperature, i.e. at high degrees of deformation, for example, constrictions occur on the edge of a covenant caused by the prevailing tangential tensile stresses there, leading to failure of the workpiece by tearing. At low Gap heights can separate materials in the range of Fluid sheath occur, with the local one in this zone Shape change is so high that the ability to change shape of the material is exhausted and no cold welding is more possible.

Under the deformability of a material is therefore understand the maximum shape change that it can endure without breaking. This is characterized Resilience over the change in fracture shape or over the toughness parameters determined from tensile tests such as Elongation at break and constriction. The fracture shape change will determined in model tests, tensile, compression or torsion tests, the fracture shape change is considered fundamentally corresponds to the logarithmic elongation at break.

Based on this, it is an object of the present invention to create a process which increases the degree of deformation enables without the workpiece quality underneath suffers.

It is also an object of the invention, through the deformation to positively influence the material properties in order to to reduce the number of subsequent heat treatments or even to eliminate them. The dimensional accuracy and surface quality should correspond to that of cold forming.

Furthermore, the method should allow in connection with Follow-up operations of individual process steps, such as repressing, Switch off hardening, polishing, cutting or cutting etc., to simplify or cheapen.

This object is solved by the features of claim 1.

The invention is based on the knowledge that the ability to change shape is not a pure material property but also depends on the process conditions.

According to the invention, a local adaptation of the Resilience to the desired deformation by means of targeted heating of the workpiece, using a combination of cold and hot forming, which has the advantages the good forming on the warm workpiece with the advantages of cold forming, such as material hardening, dimensional accuracy and high surface quality.

According to claim 2, the cold forming or the resulting thereof Solidification through a specifically influenced Temperature curve on the workpiece can be optimized.

By guiding the cooling process after cross extrusion the strength of the workpiece can also be checked locally improve, claim 3.

The heat treatment before, during and after cross extrusion can be known by means known per se, such as induction heating, Flame or laser.

For example, the preheating of the workpiece can be inductive be carried out during the targeted introduction of Process heat on the press, through a timely and targeted guided high energy laser beam.

Heat can also be dissipated using cooled grippers etc. to be controlled.

Similar means could be used for further processing of the Pellets are used in further process stages, what u.a. the lead time and energy costs are considerable would improve.

Exemplary embodiments are described below with the aid of drawings discussed the invention, which by arithmetic Verification (simulation) are confirmed.

Fig. 1

eine Prinzipdarstellung des erfindungsgemässen Verfahrens,

Fig. 2

einen Rohling, vorbereitet für das Querpressen und

Fig. 3

den resultierenden Pressling.

Show it:

Fig. 1

a schematic representation of the inventive method,

Fig. 2

a blank, prepared for cross pressing and

Fig. 3

the resulting compact.

1, a blank 100 is in its central area 40 by a heat source 30 above its recrystallization temperature warmed up. At the same time or afterwards he will with its shaft placed in a die 20 and through one Stamp 10 gripped on its shaft diameter and with a force F deformed so that an axially symmetric Bund (flange) is created.

2, the blank 100 is shown individually and with Provide dimension lines; the shaft diameter is d1, the lower shaft diameter d2 and length L0.

1 results from the method shown in FIG Pressing 100 'according to FIG. 3, which for example as Gear shaft is used. The cross extrusion has the original length L0 reduced to L1, in one area of material forming S1 are thickened material on the shaft noticeable; a bundle was pressed with a Diameter D and a collar width S2.

Werkstoff C15 (1.0441)

Umformtemperatur: 20 °C im kalten Bereich resp.
1000 °C im erwärmten Bereich

Länge L0 = 565 mm

Wellendurchmesser d1 = 75,5 mm

Schaftdurchmesser d2 = 50 mm

The following parameters were selected:

Material C15 (1.0441)

Forming temperature: 20 ° C in the cold area resp.
1000 ° C in the heated area

Length L0 = 565 mm

Shaft diameter d1 = 75.5 mm

Shank diameter d2 = 50 mm

Ein Bunddurchmesser D = 117 mm

Eine Bundbreite von S2 = 9,6 mm

Das Werkstück wurde auf eine Länge L1 von 470 mm gestaucht.

Der Bereich der Materialumformung S1 beträgt 250 mm

Der lokale Umformgrad des Kaltfliesspressens beträgt maximal 1,2

Der lokale Umformgrad des Warmfliesspressens beträgt maximal 2,0

Die Fliess-Spannung bei der Kaltumformung betrug 806 MPa, im Maximum.

Die Fliess-Spannung bei der Warmumformung betrug 225 MPa, im Maximum.

The following were achieved:

A collar diameter D = 117 mm

A waistband width of S2 = 9.6 mm

The workpiece was compressed to a length L1 of 470 mm.

The range of material forming S1 is 250 mm

The local degree of deformation of cold extrusion is a maximum of 1.2

The local degree of deformation of hot extrusion is a maximum of 2.0

The yield stress during cold forming was 806 MPa, at the maximum.

The yield stress during hot forming was 225 MPa, at the maximum.

The numerical simulation was carried out using the software MSC / SuperForge 1.0 (MacNeal-Schwendler GmbH, Munich)

During hot forming, the dynamic Softening processes largely prevented; the distribution of the yield stress is homogeneous.

Due to the partial heating according to the invention targeted use of dynamic softening processes, whereby the deformability of the material almost unchanged during the entire forming process remains.

The hardening behavior is modified locally so that the resilience of the shape change to be achieved is adjusted. So there is a "tailoring" of the material property the forming process. So then local degrees of deformation very much greater than 1.0 without intermediate annealing possible. Since the procedure is essentially a Cold cross extrusion remains is a comparable accuracy the final shape and a desired increase in strength guaranteed. By customizing the chosen local Temperature and controlled cooling can be a in in practice sufficient strength of the hot or semi-hot formed Federal generated.

To cool down and / or to maintain the desired Temperature differences are hydro and aerodynamic Means on.

Claims (3)

Process for massive forming of axially symmetrical metallic components by extrusion on one partially heated workpiece, this end is guided in a die and by a press stamp is extruded, characterized in that that only the area of by cross flow to forming federal government to a temperature which is above the Recrystallization temperature is heated, whereby maintain this temperature during the forming process is preserved, and in doing so in one go the die and the punch formed axial space the deformation behavior of the material through a targeted heat effect on the forming is adjusted so that a simultaneous warm and Cold forming of the material, with partial strain hardening, results. A method according to claim 1, characterized in that at least while heating the workpiece those existing next to the area of maximum forming Areas to be cooled. A method according to claim 1 or 2, characterized in that that the workpiece after extrusion is partially and controlled cooled.

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