GB2113130A

GB2113130A - Method of stabilizing the position of workpieces in ring rolling

Info

Publication number: GB2113130A
Application number: GB8234708A
Authority: GB
Inventors: Peter Heinrich; Dieter Gabler; Bernd Schlenkrich
Original assignee: WAELZLAGER NORMTEILE VEB
Current assignee: WAELZLAGER NORMTEILE VEB
Priority date: 1981-12-07
Filing date: 1982-12-06
Publication date: 1983-08-03
Also published as: CS253266B1; SE8206962D0; DE3242160A1; SE447216B; CS820982A1; DD206885A3; SE8206962L; GB2113130B

Abstract

The invention relates to a method of stabilizing the position of workpieces in ring rolling, more particularly for the manufacture of rolling bearing rings. The workpiece 2 is so shaped, in relation to the rolling gap profile, that centring edges 5 of the workpiece 2 centre it only on one tool, i.e. mandrel 4 or roller 1. Deformation takes place only at such edges 5 in a first phase of the deforming operation. The deformation is so large that axial forces operating on the starting part cannot displace it axially. <IMAGE>

Description

SPECIFICATION Method of stabilizing the position of workpieces in ring rolling The invention relates to a method for stabilizing the position of workpieces precisely axially in ring rolling, more particularly for the control of axial forces in the rolling gap at the start of the rolling operation.

The invention is particularly but not exclusively suitable for the manufacture of rolling bearing rings.

A device for ring rolling is known from German Federal Republic Patent Specification O/S 1 533 484, which uses a mandrel divided in the rolling gap profile and two profiled rollers. The divided mandrel is so constructed that when it is in the assembled condition the workpiece is supposed to be precisely axially positioned.

During deformation by the two rollers the two parts of the mandrel are moved apart against a closure force until positive locking is reached. It is true that the use of two rollers has the advantage that conicity of the roller rings is in practice avoided, but this arrangement is fairly expensive as regards its control technique required both for performing the method and for obtaining rings of accurate dimensions. Further, with that process no use can be made of a substantial increase in diameter, which is very useful, particularly economically.

A substantial increase in diameter can be obtained by the use of one roller and an undivided mandrel. The two tools are profiled in accordance with the final shape of the workpiece. For economic reasons an attempt must be made to use workpieces in which relatively large deviations in diameter are permitted, thus allowing very simple manufacture, for example, by turning.

When such workpieces are rolled without any particular steps being taken deviations result, particularly in the form of considerable conicity in the rolled rings. To obviate this fault, ring rolling systems have been suggested which also have, in addition to the tools (roller and mandrel) engaging with the generated surfaces, further rollers, usually conical rollers, which engage with the lateral surfaces of the ring, see Federal German Republic Patent Specification O/S 2 222 608. The conical rollers not only limit or reduce the height of the ring, but also prevent it from becoming conical.

However, it is impossible to roll cylindrical rings by the roller-and-mandrel principle without taking special steps. More particularly when rolling relatively small rings with relatively high forces such steps as laterally operating supporting rollers, or the use of a mandrel of divided profile are impracticable.

It is an object of the invention to stabilize the whole ring rolling process and substantially improve accuracy of shape and dimensions while at the same time reducing the overall dimensions hitherto required and increasing labour productivity.

The problem to which the invention relates is so to arrange the co-operation between the roller, workpiece and mandrel in a first phase of rolling, and more particularly so to construct the rolling gap profile and the starting point that the rolled rings have no conicity.

Due to tolerances in dimensions which are always present and deviations in shape and position of tools and workpieces, events occur during rolling which may result in rings of varying conicity.

In the method of stabilizing the position of the workpiece in accordance with the invention, on the roller-mandrel principle with or without supporting rollers, in a first phase of the deforming process centring edges are rolled in order to axially stabilize the position of the workpiece.

Preferably the workpiece is centred on the lateral surfaces of the pass.

According to another aspect of the invention, there is provided an apparatus for ring rolling on the roller-mandrel principle wherein the roller and/or the mandrel is adapted for initial contact with centring edges onthe workpiece, which edges are to be rolled, in a first phase of the deforming process, in order to axially stabilize the position of the workpiece.

Conicity can be substantially reduced if at the start of the rolling operation the workpiece is so firmly located axially, without the use of additional structural components, and exclusively by arranging the rolling gap and the workpiece in accordance with the invention, that the workpiece cannot be axially displaced by any axially operative component of force caused by unavoidable minor faults, more particularly errors in the alignment of the tool axes.

The locking is effected by two steps: the dimensions of the workpiece are so selected that, outside or inside a cylindrical surface of the workpiece, at least two edges reliably contact the tool (roller and mandrel) before the cylindrical surface of the workpiece contacts the corresponding surface of the tool, the result being that a gap is formed. In a first phase of the deforming operation, the action of a radiai force rolls surfaces at the contact points, until the cylindrical surface of the workpiece contacts the corresponding cylindrical surface of the tool.

The centring edges in the workpiece may be disposed on the inside and/or outside.

During rolling the profile of the roller and mandrel are transferred to the ring Advantageously, to avoid burrs on the lateral surfaces and reduce the surface pressure on the profile flanks, the width of the workpiece is smaller than the total width of the rolling gap profile. As a result rolling is rendered possible more particularly at room temperature.

To help understanding of the invention, a specific embodiment thereof will now be described in greater detail with reference to the accompanying drawings, in which: Figure 1 shows conditions in the rolling gap at the start of the rolling operation, and Figure 2 shows the conditions in the rolling gap after termination of the stabilization phase of the rolling operation.

Referring to Figure 1, the geometry of a workpiece 2 is so arranged for the invention that when centring edges 5 contact a mandrel 4, an appreciable gap 6 is formed between cylindrical surface 8 of the workpiece 2 and the cylindrical surface 9 of the mandrel 4. A force which can be applied, for example, by a roller 1 rolls a surface 7 at the centring edges in a first phase of the deforming process until the cylindrical surface of the - by now intermediately shaped workpiece 3 contacts the mandrel 4, see Figure 2.

The rolled surface 7 is sufficiently large that axial forces operating during the deforming operation cannot cause any axial offsetting during the subsequent deforming operation, which continues to be performed in known manner.

In this embodiment, the stabilizing effect of the rolled surfaces 7, in relation to the mandrel 4, is at a mainly externally profiled finished part. Similarly, with a corresponding profile of the finished part, stabilization of position can also be carried out in the profile of a roller which takes over the function of the mandrel.

Claims

1. A method of stabilizing the position of a workpiece in ring rolling, on the roller-mandrel principle with or without supporting rollers, wherein in a first phase of the deforming process centring edges are rolled in order to axially stabilize the position of the workpiece.

2. A method of stabilizing as claimed in Claim 1, wherein the centring edges are disposed on the inside of the workpiece.

3. A method of stabilizing as claimed in Claim 1 or Claim 2 wherein the centring edges are disposed on the outside of the workpiece.

4. Apparatus for ring rolling on the rollermandrel principle wherein the roller and/or the mandrel is adapted for initial contact with centring edges on the workpiece, which edges are to be rolled, in a first phase of the deforming process, in order to axially stabilize the position of the workpiece.

5. A method of stabilizing the position of a workpiece in ring rolling substantially as hereinbefore described with reference to the accompanying drawings.

6. Apparatus for ring rolling substantially as hereinbefore described with reference to the accompanying drawings.