Flexible pneumatic tensioning clamp for inner hole of slender hard and brittle thin-wall pipe fitting and working method

Abstract

The invention discloses a flexible pneumatic tensioning clamp for an inner hole of a slender hard and brittle thin-wall pipe fitting and a working method, and belongs to the technical field of composite material machining. A hollow mandrel is adopted and is provided with a center hole and a radial small hole which are communicated with each other; annular flexible ferrules are arranged at the periphery of the radial small hole; one end of the hollow mandrel seals the center hole through a screwed plug; the other end of the hollow mandrel is communicated with the center hole through a valve core; the annular flexible ferrules distributed on the flexible pneumatic tensioning clamp at intervals expand in the radial direction under the action of compressed gas to reduce stress concentration and homogenization errors of sharp points on the surface of a rough inner hole in the clamping process while supporting and clamping the pipe fitting, so that the supporting rigidity of the pipe fittingis improved, and the coaxiality of the pipe fitting is guaranteed; and meanwhile, two symmetrically-arranged thin-wall grinding wheel grinding heads are adopted to form two symmetrical point contactswith the machined pipe fitting to conduct same technological parameter and synchronous grinding machining, so that the radial grinding force in the machining process is offset, and workpiece breakingor machining deformation caused by a too large grinding force is avoided.

Description

technical field [0001] The invention belongs to the technical field of composite material processing, and relates to a flexible pneumatic tensioning fixture for the inner hole of a slender, hard, brittle, thin-walled pipe fitting and a working method. Background technique [0002] Thin-walled pipe fittings such as slender, hard and brittle ceramics or ceramic matrix composites have important applications in high-end equipment such as aerospace and nuclear power plants. The problem has become a problem that needs to be solved urgently in restricting its application. Especially with SiC f / SiC composite material filament winding process and CVI densification prepare and form slender hard and brittle ceramic pipe fittings, the length is mostly 1000-4000mm, the diameter is 8-20mm, the wall thickness is only 1mm, and the surface of the inner hole is relatively rough, and the overall rigidity of the pipe fittings Low, difficult positioning and clamping, high machining accuracy r...

AI Technical Summary

Problems solved by technology

[0002] Thin-walled pipe fittings such as slender, hard and brittle ceramics or ceramic matrix composites have important applications in high-end equipment such as aerospace and nuclear power plants. become a difficult problem to be solved urgently in restricting its application

Especially with SiC f / SiC composite material filament winding process and CVI densification prepare and form slender hard and brittle ceramic pipe fittings, the length is mostly 1000-4000mm, the diameter is 8-20mm, the wall thickness is only 1mm, and the surface of the inner hole is relatively rough, and the overall rigidity of the pipe fittings Low cost, difficult positioning and clamping, high requirements for machining accuracy of the outer surface, and extremely brittle fracture during the machining process have brought great challenges to the precision machining of the outer circle surface, which is almost impossible to achieve with existing machining methods

[0003] Patent CN106624010A discloses an auxiliary tooling for slender and thin-walled tubular workpieces. There is a mandrel in the middle of the tooling, which is fixed by a tapered sleeve at the end. The mandrel supports the pipe; however, the mandrel needs to be taken out of the pipe or Put it in, so the mandrel can only play a supporting role but not a fixing role

And it is aimed at auxiliary tooling or processing methods for slender and thin-walled pipes with strong plasticity. However, there are no relevant literature records on the processing fixtures and processing methods for the outer surface of slender, hard and brittle thin-walled pipes with rough inner hole walls.

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