Method for measuring combination strength of investment casting shells

Abstract

The invention discloses a method for measuring combination strength of investment casting shells. The method comprises the following steps of: (1) gradually preparing a multi-layer shell I in a wax mould recess, and grinding the part not being filled by the shells I on the upper part of the recess to make the depth of the recess be equal to the average thickness of the shells; (2) splicing wax moulds to form a wax mould III provided with a recess and utilizing the shells I and a wax plate as bottom surface, and gradually preparing a multi-layer shell II in the recess; (3) clamping a step-shaped shell obtained by dewaxing or roasting in a mould of a universal tester, locating the shell by the cooperation of fillers, baffles and upper and lower moulds with the universal tester, and measuring the combination strength of the layers; and (4) calculating shear strength T through critical load F and shearing area A, T is equal to F / A. The method for measuring combination strength of investment casting shells disclosed by the invention can be used for accurately locating the combination surface of the layers of the shell to directly measure the combination strength of the layers, the preparation of the shell is in accordance with the actual condition, the reliability is strong, the operation is simple, and the problem that the combination force of the investment casting shells is difficult to evaluate is solved.

Description

technical field [0001] The invention relates to the technical field of investment casting shells, in particular to a method for measuring the bonding strength between investment casting shells. Background technique [0002] In investment casting, the shell is the cavity formed by the metal liquid, and its quality will have an important impact on the casting. Since the mold shell is prepared in layers, the bonding between the two layers is affected by many factors. Any instability in the process may lead to the separation and fragmentation of the two layers, resulting in inclusions, one of the main defects of investment castings. In particular, different layers of the mold shell are generally composed of different materials or different slurry viscosities and sanding particle sizes of the same material, and the combination of layers is very complicated. [0003] At present, there is no relevant report on the determination of the interlayer bonding strength of the investment ...

AI Technical Summary

Problems solved by technology

The interlayer bonding force of the shell is very large, exceeding the general adhesive strength, and the strength of the shell itself, especially the strength at room temperature, is not high, and it cannot bear the force of local clamping, so it cannot be broken by using glue or loading. Methods

The mold shell is prepared on the wax model. The process of grouting and sanding has a certain degree of randomness. There are differences in the thickness of the samples, and the joint surface between the layers is a rough surface covered with sand particles, which makes the mold shell layer The positioning of the bonding surface is very difficult

The interlayer bonding strength of the shell is closely related to the preparation process. Only the shells prepared under the actual process conditions can characterize the interlayer bonding of the shell, which adds difficulty to the measurement of the bonding strength.

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