NC bending core head for thin walled tube of aluminum alloy with major diameter and design method thereof

Abstract

The invention relates to an NC bending core head for a thin walled tube of aluminum alloy with a major diameter and a design method thereof, wherein the core head comprises an core head(2), a mandrel core pin(1) and a connection member between the core heads(3). Further, the core heads are connected in a ball-and-socket structure manner. The eccentricity delta of the ball centre of the eccentric core (2) in the internal of the core head is delta=h / k, wherein h is the distance between the ball centre of core head and the large end of the core head, and k is the thickness of the core head. The inside radius d0' and the outer radius d0 of the core head, and x2 corresponding to the largest angle theta 2 of the core are determined, so that the relationship between the core distance h and the largest angle theta 2 of the eccentric core is established. Through finite element modeling, the scope of the largest angle theta 2 between the eccentric cores (2) is determined, and furthermore, the value range of h is determined. According to invention, an interference area between rotary core heads, and excess interference between the core heads and the tubing outside arc surfaces are reduced, so as to be suitable for bending and shaping of the tubing under various bending radii. Besides, the possibility of tubing wrinkling and the degree of thinning could be decreased, without increasing the flat degree of tubing.

Description

1. Technical field [0001] The invention relates to the field of mechanical processing, in particular to an eccentric core head of an aluminum alloy large-diameter thin-walled tube numerically controlled bending mandrel and a design method thereof. 2. Background technology [0002] With the increase of the diameter of the aluminum alloy tube and the decrease of the bending radius, the wrinkling of the aluminum alloy large-diameter thin-walled tube will become more and more likely to occur during CNC bending. At present, the industry often adopts the method of reducing the contact gap between the pipe and the mold to reduce the possibility of pipe wrinkling, but this will increase the degree of thinning and flattening of the pipe. In the CNC bending process of aluminum alloy large-diameter thin-walled tubes, the parameters of the mandrel will have an important impact on the wrinkling, thinning and flattening of the tubes. The core head structure of the traditional thin-walled...

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Problems solved by technology

The disadvantage of this structure is that due to the characteristics of the symmetrical structure, the range of interference between the core head and the core head during rotation is relatively large. The deformation of the bending radius is coordinated; at the same time, because the symmetrical core structure is prone to excessive contact with the outer arc surface of the pipe, the degree of wall thickness reduction of the pipe is increased

In the invention patent application document with the application number 200710018458.X, a design of a mandrel for flexible pipe bending is disclosed. Although the mandrel of this design can increase the degree of rotation of the mandrel during the pipe bending process, the invention still uses Symmetrical core head, so it is not applicable to the CNC bending process of aluminum alloy large-diameter thin-walled tubes

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