Diameter-expanding and bend-pressing forming core head for short radius elbows

Abstract

The invention discloses a diameter-expanding and bend-pressing forming core head for short radius elbows, which is formed by sequentially connecting an extension section, a deformation section and a shaping section from front to back, wherein the three sections are sequentially connected to form an arietiform core head mold with a smooth external surface. A central arc line of the deformation section is an involute, the bending radius of the involute transitions continuously and smoothly from an initial bending radius R0 to the final bending radius from front to back. A cross section, vertical to the central arc line, of the deformation section is an elliptic cross section, and the vertical diameter and the horizontal diameter of the elliptic cross section both vary with the arc length li of a central arc line 1 from front to back. The extension section is a straight section. A central arc line 2 of the shaping section is a circular arc, and the cross section, vertical to the central arc line 2, of the shaping section is a circular cross section. The core head can conveniently make high-precision high-quality metal elbows including high-quality short-radius elbows of general specifications as well as heavy-calibre thin-wall short-radius elbows.

Description

technical field [0001] The invention relates to a forming die core for a short-radius elbow used in the field of metal pipe fittings manufacturing, and in particular to a forming core for expanding a diameter and pushing and bending a short-radius elbow. Background technique [0002] At present, the intermediate frequency heating expansion push bending method (expansion push bending method) is recognized as a metal seamless elbow manufacturing method suitable for mass production, with uniform wall thickness and high production efficiency. Radius elbow (bending radius R = 1.5D n ,D n For the nominal caliber) has quite mature technology. And the short radius elbow (R=D n ), because the bending radius R is small, the curvature is large, and the lengths of the outer arc and the inner arc differ greatly, resulting in a large difference in the variables of the inner arc and the outer arc during the expansion push bending, and the technical difficulty in the manufacturing proces...

AI Technical Summary

Problems solved by technology

In the process of manufacturing elbows by expanding diameter push bending, the design of the horn core of the forming die is the key technology. In the previous mold design of the horn core, the central arc was changed from the initial bending radius R 0 When gradually changing to the finished product R, one-stage method, two-stage method or multi-stage method are often used. The cross-section of the croissant core is circular, and it evenly expands from the inner diameter d of the billet. 0 Increase to finished product inner diameter d k , this method is effective for the manufacture of long-radius elbows, but when used for the manufacture of short-radius elbows, it will cause problems such as warping, thinning and tearing, and cannot obtain qualified finished products

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