Internal expansion fixture for thin-walled parts

Abstract

The invention discloses an internal expansion fixture for thin-walled parts. The fixture comprises: a machine tool connection plate, a tie rod flange plate, a positioning seat, and a fixed mandrel shaft. When the fixture disclosed by the present invention is in operation, under the action of the pull force of the pull rod of the machine tool, the pull force is transmitted to the elastic expansion sleeve through the pull rod flange and the connecting rod. Since the elastic expansion sleeve is limited by the connecting rod, it cannot rotate freely and can only move axially on the tapered surface of the fixed mandrel. At the same time, when the elastic expansion sleeve moves axially, it passes through the tapered surface of the fixed mandrel, and converts the pulling force into a radial expansion force and a pulling force toward the positioning surface. It is because of the above-mentioned pulling force toward the positioning surface that the parts will be automatically pressed against the positioning surface, and the parts will not be pressed tightly due to the operator's mistakes, resulting in gross errors in the processing of the parts. Therefore, the product quality of the parts is effectively improved, and the processing benchmark of the next process is guaranteed.

Description

technical field [0001] The invention relates to an internally expanding clamp, in particular to an internally expanding clamp for fixing thin-walled parts. Background technique [0002] With the continuous improvement of machining accuracy, the requirements for tooling and fixtures for parts processing are also getting higher and higher, especially for the processing of thin-walled cylindrical parts. The earliest internal three-jaw anti-expansion tooling fixture has basically been eliminated, such as figure 1 , the disadvantage of this fixture 10 is mainly that the stress points are on the three claws 11. After the processing is completed, due to the elastic deformation of the thin-walled parts, the roundness of the inner hole will be deformed so much that it cannot meet the product drawings at all. Require. [0003] Instead, the internal expansion fixture 20, such as figure 2 , it adopts the whole inner hole contact tensioning method. The fixture 20 is fixed to the mac...

AI Technical Summary

Problems solved by technology

However, it has been found in actual use that since the elastic expansion sleeve 26 can rotate freely, and its elastic wall is quite thin, the effective supporting force is not very large, especially when the radial force generated when cutting grooves is relatively large, it will The radial jump of the processed parts is usually not guaranteed, and the general tolerance can only be controlled at about 0.1mm

In addition, there is also a disadvantage that this type of clamp is subjected to the pulling force F of the pull rod 28, such as image 3 As shown, when the tension F is converted into a radial expansion force f through the connecting rod 28 and the tapered surface 27 of the elastic expansion sleeve 26, the parts are only subjected to the tension force, while the positioning surface 25 of the parts and the fixture It is necessary to apply pressure to the positioning surface through the palm of the operator to ensure that one end of the part is closely attached to the positioning surface 25, so as to ensure the runout of the end face of the part. In this case, the runout is generally controlled at about 0.08mm

However, due to the addition of manual operations, it is easy to appear that the operator installs the parts at will and does not press the end face of the part on the positioning surface 25, resulting in a large machining error of the part.

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