A method for preparing a coating by thermal spraying on large-size bent pipe workpieces

Abstract

A method for thermal spraying preparation of a coating on a large size bending pipe workpiece is as follows: first the bending pipe workpiece surface is pretreated, a specially-designed bending pipe spraying tooling is used for clamping and fixing, the specially-designed bending pipe spraying tooling mainly includes a tooling body, a supporting frame, a motor, a drive chain wheel, a driven chain wheel, a main shaft, a countershaft, a fixing sleeve and a protection plate, the workpiece is fixed on the main shaft and the countershaft through the fixing sleeve and fastening screws, and can be driven, by the drive chain wheel, the driven chain wheel, the main shaft and the countershaft, to rotate, wherein the drive chain wheel, the driven chain wheel, the main shaft and the countershaft are driven by the motor. When in spraying, a spray gun respectively sprays once along A, B and C track lines to form one spray pass, and sprays by repeated multiple passes until needed coating thickness is obtained, and the workpiece is cooled by high-speed air curtain. The method can ensure uniform coating thickness, texture and property of arc length and outer circumference direction of the bending pipe workpiece, can effectively prevent the component deformation, and is especially suitable for thermal spraying preparation of the coating on large size bending pipe workpiece with the curvature radius greater than or equal to 2m, length less than 2m and diameter between 30-140mm.

Description

technical field [0001] The invention relates to a thermal spraying process in the technical field of modern material surface engineering, in particular to a method for preparing a coating on large-sized bent pipes or bent rods using thermal spraying technology. Background technique [0002] Thermal spraying technology first appeared in Switzerland in the early 20th century, and a large number of achievements have emerged in the following one hundred years, including the development of various thermal spraying equipment, the development of new thermal spraying materials and the application of new technologies. Thermal spraying technology is a process in which the coating material (powder or wire) is fed into a certain heat source (arc, combustion flame, plasma, etc.) . Thermal spraying coating has a wide range of materials, almost all metals, alloys, ceramics and even organic polymer materials can be sprayed, endowing the substrate with excellent properties such as wear resi...

AI Technical Summary

Problems solved by technology

However, the center line of the bent pipe workpiece is an arc line. If the rotation axis of the workpiece is not selected properly, it is difficult to ensure consistent coating thickness in the arc length direction and the outer circumference of the bent pipe workpiece, and the coating structure and performance are uniform. sex is greatly affected

The second is that a large number of bent pipe (rod) parts are thin-walled or have a large length / diameter ratio. Such large-sized workpieces have limited rigidity and are sensitive to temperature. During the spraying process, bending deformation is prone to occur problems, and may even cause the workpiece precision to fail to meet the specified requirements

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