Abstract
The rotary forging process is based on a recognition of the fact that the axial force required to effect a desired deformation during, for example, an upsetting operation may be reduced if the plastically deforming zone is confined throughout to a small region beneath the upper platen. The top portion of the workpiece is then rotated through this plastic zone thus resulting in a progressive deformation.
An experimental rotary forging machine has been designed and constructed which incorporates a lower platen capable of axial movement only, whilst the upper conical platen is capable of rotation about the central axis of the machine and also about its own inclined axis.
The principal design features of the experimental machine are described and the results of some preliminary experiments using the machine are presented. Operation of the experimental machine has demonstrated the feasibility of the process.
The effect of the axial force on the rotary forging of cylindrical specimens having a height/diameter (H/D) ratio of unity and for a fractional reduction of 0.5 is discussed. Pure lead at ambient temperature was used, as a model material, to simulate the rotary forging of steels in the approximate temperature range of 700-1400°C. A comparison is made between the axial force required to rotary forge and conventionally upset identical pure lead cylinders. It is shown that the optimum axial force required for slow rotary forging is a small fraction of that required for the conventional slow upsetting of circular cylinders having H/D ratios of less than unity.
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