Method and apparatus for molding by forging

Abstract

The invention is directed to provide a forming method and a forming apparatus that are, without extending a processing time compared with the conventional practice, capable of sufficiently lubricating a formed object and forming at safety without the lubricant igniting under pressure. In an extruding apparatus, a workpiece is successively transferred to a series of press stages, a conveying unit successively transferring the workpiece is provided with a nozzle for spraying the workpiece with lubricant, and the workpiece and the nozzle are located in fixed relative positions to each other in spraying the workpiece with the lubricant.

Description

TECHNICAL FIELD [0001] The present invention relates to a forging method and apparatus of forming a material at a temperature below its transformation point into a cup-shaped product such as a constant velocity universal joint outer race, and a shaft-shaped product. BACKGROUND ART [0002] Among conventional forging methods for producing cup-shaped or shaft-shaped mechanical parts, a cold forging method is commonly used where a material is formed at a temperature below its transformation point by a die and a punch (e.g., see Patent Document 1 listed below). In this method, the material undergoing the forging must be coated with lubricant film, or otherwise, the forging apparatus is seized. A cylindrical workpiece with an unwrought surface of approximately 75 in Rockwell hardness Scale B turns to have a forged surface of 100 or even higher in Rockwell hardness Scale B after it undergoes the first stage of profiling a core end, the second stage of preliminarily upsetting, and the third ...

AI Technical Summary

Benefits of technology

The present invention provides a forging method and apparatus that can sufficiently lubricate a formed object and form at safety without the lubricant igniting under pressure. This is achieved by spraying the heated workpiece with lubricant multiple times during the forging process, which allows for better lubrication and reduces the risk of ignition. The method also includes steps of oil bath forging, where the material is soaked in lubricant in advance, but the adhesion of the lubricant film is weak, so it is necessary to repeat the bonderizing process again before the ioning and coining steps in the forging procedure. The invention aims to address these problems by providing a more efficient and safe forging method.

Problems solved by technology

Among the aforementioned lubricating methods, the bonderizing is unsatisfied to drastically reduce a lubricant film thickness after a single step of forming, and the procedures with successive forming steps at a greater forming rate often bring about disappointing lubricating effects.

Moreover, with any means for insufflating with the lubricant, it is hard to uniformly coat the workpiece or the die, and if a greater forming rate causes the lubricant film to be discrete, the formed product may be defective, and this is also undesirable for work environments.

In the case of the oil bath forging, however, lubricant is prone to be confined in space between the material and the bottom of the cavity during the forging process, depending on the material shape.

However, providing such a drain is insufficient because after forming, the formed product may cling to the punch as it is raised together with the punch in preparation for the next press action, which may result in the formed product being pressed again by the punch.

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