Internal Spinning Forming Method of Bellows

Abstract

The invention discloses an internal spinning forming method for a corrugated tube. The internal spinning forming method for the corrugated tube comprises the following steps that a tube billet is installed on a main shaft of a spinning machine, and a length thin tube is driven by the main shaft to rotate; the interior and the exterior of the tube billet are respectively provided with an inner spinning roller and an outer spinning roller for forming corrugations; the inner spinning roller and the outer spinning roller synchronously work; a feed rate of the inner spinning roller is paused until a gap between a convex molded surface of the inner spinning roller and a concave molded surface of the outer spinning roller is 1.1 to 1.3 times of the thickness of the tube billet, and the gap is kept for forming for 3 to 5 seconds until one position machining is finished; the inner spinning roller and the outer spinning roller synchronously move for one pitch of waves along the axial direction of the tube billet, and the steps are repeated until the corrugated tube of a required length is formed. The internal spinning forming method disclosed by the invention is higher in forming precision and low in forming cost; moreover, a metallographic structure is even and compact due to grain refinement and spinning deformation of the corrugated tube during a spinning process; meanwhile, grains are squashed and stretched to form a fibrous tissue in a spinning direction; product quality is high, and the service life is greatly prolonged.

Description

technical field [0001] The invention relates to a forming method, in particular to an inner spinning forming method of a corrugated pipe. Background technique [0002] At present, the forming processes of bellows mainly include hydroforming, spinning forming and welding forming. Hydroforming is the most commonly used method for bellows forming. Using the liquid pressure in the tube blank, the tube blank is bulged in the confining ring until it yields along the ring direction. Use this method more often. The spinning forming process is mainly used to process large and medium-sized bellows. The tube blank is installed on the spindle of the spinning machine, and the tube blank is driven by the spindle to rotate. At the same time, the rotary wheel moves along the contour of the corrugated tube. The axial feed motion forms the corrugations. The welding forming is mainly through the process method of "plate beading-rolling-welding", that is, first pressing the wave on the plate...

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Problems solved by technology

[0003] At present, the commonly used bellows are obtained by segmented forming and multi-section welding process. This process mainly has the following process disadvantages: (1) The welding area is prone to stress concentration, which reduces the fatigue strength of the product. The weld area is in the Microcracks may occur and expand during long-term storage, which will affect the service life of the product; (2) A large number of longitudinal welds, circumferential welds, especially cross welds, make it difficult to guarantee the welding quality of bellows, according to the design It is required that the weld seam quality of the product should be 100% inspected, and the weld seam inspection efficiency is low and the cost is high; (3) The product deforms greatly during the welding process, and the product forming accuracy and consistency are poor

Using the above-mentioned equipment to process corrugated pipes with a pipe diameter greater than 250mm and a pipe wall thickness of 2.7 to 3.5mm, there are always deformation defects due to the large pipe diameter and thin wall thickness during the forming process, and the processing of the bellows cannot be completed.

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