Method and device for forging a workpiece in bar form

Abstract

A description is given of a method and a device for forging a rod-shaped workpiece (5) which is deformed with the aid of forging tools (1, 2, 3, 4) in the sense of a cross-sectional displacement perpendicular to the forging axis (a) and is subjected to an axial advancement and possibly a rotation about the forging axis (a) during the pauses in the engagement of the forging tools (1, 2, 3, 4). In order to achieve an advantageous grain refinement, it is proposed that the workpiece (5) is deformed in the sense of the cross-sectional displacement perpendicular to the forging axis (a) in a bending zone (13) between two central supports (11) by means of the forging tools (1, 2, 3, 4) acting on the workpiece (5) radially in relation to the forging axis (a).

Claims

1. A method for forging a rod-shaped workpiece, the method comprising: providing forging tools having molding surfaces between inlet-side and outlet-side molding surfaces for a mold cross-section that is coaxial to a forging axis, the inlet-side and outlet-side molding surfaces forming two central supports, the forging tools being arranged in pairs opposite one another, the forging tools forming a bending zone between the two central supports; introducing the workpiece into the inlet-side molding surfaces and into the bending zone; deforming the workpiece, with the aid of the forging tools, as a result of a cross-sectional displacement of the forging tools perpendicular to the forging axis such that the forging tools engage the workpiece; subjecting the workpiece to a plurality of axial advancements, and possibly a rotation about the forging axis, during pauses in the engagement of the forging tools; bending, in the bending zone, the workpiece out of a position coaxial to the forging axis (a) via the forging tools acting on the workpiece radially in relation to the forging axis; and after the bending out and after an axial advancement of the workpiece within the bending zone, bending, in the bending zone, the workpiece back into the forging axis via the forging tools acting on the workpiece radially in relation to the forging axis.

2. The method according to claim 1, wherein the workpiece is subjected to a forging reduction in front of the bending zone in the advancement direction.

3. The method according to claim 1, wherein the workpiece is subjected to a cross-sectional reduction and/or a finishing operation after the bending zone in the advancement direction.

4. The method according to claim 2, wherein the workpiece is supported centrally for the bending deformation during the forging reduction and/or during finishing.

5. A device for carrying out a method for forging a workpiece, the device comprising: inlet-side molding surfaces; outlet-side molding surfaces; and first, second, third, and fourth forging tools which are arranged in pairs opposite one another in relation to a forging axis, the first, second, third, and fourth forging tools being disposed between the inlet-side molding surfaces and the outlet-side molding surfaces, wherein the first, second, third, and fourth forging tools have molding surfaces; wherein the device has a forging axis; wherein a mold cross-section of the inlet-side molding surfaces and the outlet-side molding surfaces is coaxial to the forging axis; wherein the inlet-side and outlet-side molding surfaces form central supports; and wherein the molding surfaces of the first, second, third, and fourth forging tools form a mold cross-section that is eccentric in relation to the forging axis in such a way that the workpiece, between the central supports, is bent out of a position coaxial to the forging axis and is bent back into the forging axis.

6. The device according to claim 5, wherein the inlet-side molding surfaces form a mold cavity that tapers in an advancement direction.

7. The device according to claim 5, wherein the outlet-side molding surfaces form a mold cavity that tapers in an advancement direction and/or a finishing tool.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The method according to the invention for forging workpieces will be explained in greater detail with reference to the drawing. In the drawing

(2) FIG. 1 shows, in a view of the moulding surfaces, two of the four forging tools of a forging device according to the invention, said forging tools being arranged in pairs opposite one another and being set so as to form a mould cavity,

(3) FIG. 2 shows a sectional view along the line II-II of FIG. 1,

(4) FIG. 3 shows a sectional view along the line III-III of FIG. 1,

(5) FIG. 4 shows a sectional view along the line IV-IV of FIG. 1,

(6) FIG. 5 shows a sectional view along the line V-V of FIG. 2, and

(7) FIG. 6 shows a sectional view along the line VI-VI of FIG. 3.

WAY OF IMPLEMENTING THE INVENTION

(8) Of the forging device constructed in a known manner, only the four forging tools 1, 2, 3, 4 are shown in the illustrated exemplary embodiment, said forging tools being arranged in pairs opposite one another and being able to be acted upon radially in relation to a forging axis a, the setting shown forming the mould cavity for a rod-shaped workpiece 5 that is indicated in dash-dotted line. Said forging tools 1, 2, 3, 4 form inlet-side moulding surfaces 6, which create a mould cavity coaxial to the forging axis a and which give rise to a cross-sectional reduction on account of their course being inclined in the advancement direction 7. On the outlet side, moulding surfaces 8 are provided, which likewise define a mould cavity coaxial to the forging axis a and advantageously ensure an additional cross-sectional reduction, which aids the central guidance of the workpiece 5 in the region of the outlet-side moulding surfaces 8. The outlet-side moulding surfaces can also be used as a finishing tool.

(9) Between the inlet-side and outlet-side moulding surfaces 6, 8, the forging tools 1 to 4 form moulding surfaces 9 which define for the workpiece 5 a mould cross-section that is eccentric in relation to the forging axis a, as can be seen in particular in FIG. 4, in which it is possible to see the transverse displacement of the workpiece 5 in relation to the forging axis a that is brought about by the moulding surfaces 9. The axis of the workpiece cross-section is denoted 10 and runs in an offset manner in relation to the forging axis a, so that the workpiece 5 is bent out in relation to the inlet-side and outlet-side supports 11 which are formed by the moulding surfaces 6 and 8 and guide the workpiece 5 coaxially in relation to the forging axis a. The return of the workpiece 5 into a position which is coaxial to the forging axis a takes place via transition surfaces 12, as can be seen in particular in FIG. 1.

(10) By providing the moulding surfaces 9 which bring about a transverse displacement of the workpiece cross-section, a bending zone 13 is thus created by the forging tools 1, 2, 3, 4, in which bending zone the workpiece 5 is exposed to additional shear stresses over the cross-section, which ensure a corresponding grain refinement over the entire cross-section of the workpiece 5, the latter being subject to an advancement with simultaneous rotation between the engagements of the forging tools 1 to 4. The forging-induced workpiece deflection transversely to the forging axis a is particularly clear in FIGS. 1, 5 and 6. For clarity reasons, the respective forging tool 1 or 2 located between the cut-away forging tools 3 and 2 or 1 and 4 is omitted in FIGS. 5 and 6.

(11) The invention is of course not limited to the exemplary embodiment shown. For instance, the grain refinement according to the invention can also be used in the case of workpieces having a right-angled cross-section. In this case, the workpiece rotation during the advancement steps is omitted. Although it is advantageous to ensure the entire deformation process by the forging tools 1 to 4 arranged in pairs opposite one another, the invention is not limited to this embodiment. For instance, the supports 11 formed by the moulding surfaces 6 and 8 could be arranged upstream and downstream of the forging tools, so that the forging tools merely have the task of forming a bending zone 13 for the workpiece 5, for which purpose only two oppositely arranged forging tools are required. The supports 11 could be formed by upstream and downstream forging tools, but this is not mandatory since the supports 11 for the central guidance of the workpiece 5 coaxial to the forging axis a need not be in the form of forging tools.

(12) It would also be possible to provide three central supports 11 for the workpiece 5, in order to be able to arrange a bending zone 13 between each of said supports so that the workpiece 5 is bent twice in succession.