High rate NiTi alloy pipe blank hot extruding mold

Abstract

The present invention relates to hot extruding technology, and is especially one kind of hot extruding mold for extruding NiTi shape memory alloy pipe blank to form. The technological process includes the steps of: smelting, forging, machining extruded blank, preheating the extruded blank, painting lubricant to the extruded blank, heating the extruded blank to 960-1130 deg.c under inert gas protection and maintaining for 20-30 min, preheating mold, painting lubricant to the mold, hot extruding in speed of 400-500 mm / s, and annealing. The extruding mold is split combined cavity mold, and has simple replacement and long service life. The present invention has the advantages of material utilizing rate up to 89 %, high quality of microscopic pipe blank structure, long mold life, high heating temperature, low production cost and simple process and apparatus.

Description

[0001] This application is a divisional application of a Chinese invention patent application. The filing date of the original application: April 27, 2005, the application number: 200510046321.6, and the name of the invention: a high-speed hot extrusion method for NiTi alloy tube billet and its special mold , Publication No.: CN1853815A; Since the hot extrusion method and the special mold in the original application do not belong to a general inventive concept, the applicant submitted this divisional application according to the request of the examiner teacher. technical field [0002] The invention relates to an alloy tube blank hot extrusion forming technology, in particular to a NiTi shape memory alloy tube blank hot extrusion die, which is mainly used in the forming of a NiTi alloy tube blank hot extrusion process. Background technique [0003] NiTi alloy, its composition is Ni50.8%Ti(at). At present, when this alloy is used to make pipes for pipe joints and pipes are us...

AI Technical Summary

Problems solved by technology

At present, when this alloy is used to make pipes for pipe joints and pipes are used as a primary processing product, the method of machining and drilling is usually used. The disadvantages are low processing efficiency, time-consuming and material-consuming, high cost, and the performance of the alloy depends on the microscopic structure of the forging billet. good or bad organization

Chinese patent application (application number 01140301.2) discloses a method for directly preparing NiTi shape memory alloy pipe joint pipes from powder, which can significantly reduce the overall cost, but due to the reaction heat sintering, the alloy oxygen content is relatively high, and the performance is slightly Poor, unable to meet higher requirements of performance

Mainly due to the high deformation resistance of the alloy (the deformation resistance of hot working at 800°C is equivalent to the deformation resistance of low alloy steel at room temperature and cold processing), the extrusion temperature is high, and it is difficult to form by the traditional piercing extrusion process; in addition, the NiTi alloy is heated Oxygen absorption tends to be serious in deformation and deformation, and it has high requirements on heat treatment and lubrication technology. It is prone to defects such as cracks, eccentricity and wrinkles when extrusion tubes are squeezed, and the scrap rate is high. It is a difficult-to-process profile.

Chinese patent application (Application No. 92109984.3) discloses a process for cold drawing of tube blanks, but there is no detailed explanation for the wrapping hot extrusion method of tube blanks

Images