Apparatus and method for outwardly turning straight-side holes on hollow closed parts with complex curved surfaces

Abstract

The invention discloses a device and method for flanging a straight flange hole outwards in a complicated curved surface hollow closed part and belongs to the technical field of precision forming of plate and pipe parts. The device comprises a needle bush, rolling needles and a central spindle. The central spindle is driven by a machine tool to conduct automatic rotation and axial feeding. The central spindle drives the needle bush and the rolling needles to rotate with the central spindle as the center. Meanwhile, the rolling needles rotate automatically under the action of friction force of the central spindle and the hole wall of the part. The needle bush, the rolling needles and the central spindle cooperate mutually to flange the hole in a preformed protrusion of the part. During hole flanging, firstly, the protrusion is preformed on the part; secondly, a hole flanging device is gradually pressed into the preformed hole to flange a material to be machined; and finally, the hole flanging process is completed through sizing and shape correcting. The hole flanging device is simple; the technological difficulty of flanging the straight flange hole outwards in the hollow closed part is effectively lowered; the friction force between the device and the part is little; the dimensional precision of hole flanging is high; and the edge of the flanged hole can be effectively prevented from cracking.

Description

technical field [0001] The invention relates to the technical field of precision forming of plate and tube parts, in particular to a device and method for turning outwards straight-side holes on hollow closed parts with complex curved surfaces. Background technique [0002] When connecting closed tubular, plate-shaped or other shaped hollow components with other parts, it is usually necessary to turn straight-sided holes. The turned holes usually include assembly holes, positioning holes, electrophoretic paint holes, etc. This kind of parts with straight-sided holes is widely used. It is used in the fields of aviation, aerospace, nuclear power and automobile manufacturing. For example, the sub-frame of an automobile is a typical hollow part, and various types of holes are turned on it to connect with other parts. Usually, the internal high-pressure process is used to form the pipe fittings, and then hydraulic punching. For example, in the nuclear power industry, a plurality ...

AI Technical Summary

Problems solved by technology

When turning holes in closed tubular or other special-shaped hollow members, ordinary punching methods are often used to directly punch holes from the outside of the pipe. Turning holes inward, but it is impossible to turn the hollow closed parts outward, and the hollow closed parts usually need to be connected with other external parts such as welding, and the outward turning hole side wall is required as the connection medium; and the turning holes of complex curved surfaces, Due to the radian and certain corners of the base surface of the hole, the strain of the material at different positions is different after the hole is turned, and the instantaneous punch directly turns the hole will cause partial cracking at the edge of the hole, which will affect the rigidity and service life of the product.

[0004] Chinese patent application CN201510167803.0 discloses a progressive hole-turning process without dies. This method uses the high-speed rotation of the tool head with a small diameter and the matching circumferential movement around the central axis of the hole-turning to achieve a local small area. The method of contact gradually forms the turning hole. This technology can form the turning hole of the complex surface that is difficult to realize by ordinary technology, but its forming efficiency is low, the movement of the forming tool is complicated, and it has high requirements for auxiliary equipment. In addition, the local asymmetric single point The contact state causes problems such as uneven force in the turning area and difficulty in guaranteeing the forming accuracy.

[0005] In addition, in the above two process methods, the friction mode between the turning device and the parts is sliding friction, the friction force is relatively large, and the friction conditions are poor, which may easily cause problems such as scratches on the inner wall of the turning hole and poor dimensional accuracy.

In addition, the relatively large frictional force will be accompanied by corresponding frictional heat, which will aggravate the oxidation of the side wall material of the turning hole, reduce the surface quality of the parts and the corrosion resistance of the hole wall, etc.

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