Method for judging shearing strength of composite layer of pipe

Abstract

The invention relates to a method for judging the shear strength of a composite layer of a pipe. The method comprises the following steps: cutting a composite pipe sample with a set length L; changing the temperature of the composite pipe sample according to the set temperature upper and lower limits and the temperature cycle period, and obtaining the extension lengths b and c of the steel wires at the two ends of the composite pipe sample; and obtaining the steel wire penetration percentage of the end surface of the composite pipe sample by using the steel wire extension lengths b and c and the composite pipe sample L, and judging the shear strength of the pipe composite layer. The method is short-term in high-temperature and low-temperature environments. The shear strength change phenomenon of the steel wire and the adhesive resin is stored and accelerated, so that the stress release process of the pipe is accelerated, the reasons of the shear strength change can be found in time in the manufacturing process of the composite pipe so as to adjust the manufacturing process, and the inherent quality of the composite pipe product is improved; the comprehensive performance and the performance stability of the steel wire mesh framework polyethylene composite pipe are improved, so that the service life is prolonged.

Description

technical field [0001] The invention relates to the field of composite pipes, in particular to a method for judging the shear strength of a composite layer of pipes. Background technique [0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art. [0003] Steel mesh reinforced polyethylene composite pipe is based on pipeline-grade polyethylene, and the steel wire coated with adhesive resin is continuously wound left and right to form a network structure as the reinforcement. The steel wire is connected as a whole, and the composite pipe is formed by melting and compounding. The polar chemical bonds in the molecular chain of the bonding resin form van der Waals force with the surface of the steel wire, which restricts the movement of the steel wire in the pipe. The apparent test of this van der Waals force is the shear strength of the composite layer. [0004] During the producti...

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Problems solved by technology

[0004] During the production process of steel mesh reinforced polyethylene composite pipes, the steel wires are tightly and orderly arranged, and are in a relatively tight state when winding, resulting in stress between the steel wire and the adhesive resin layer. Due to the existence of van der Waals force between the layers, the steel wire and the bond If the coating effect of the bonding resin is not good (such as the difference in coating temperature, the wind speed of the wind ring, etc.), the adhesion between the composite layers is weak, and the bond between the steel wire and the bonding resin will change over time and the environment. The phenomenon of stress release occurs due to the change, and the stress release causes different degrees of steel wire movement, thereby forming a steel mesh skeleton. The bonding strength of the adhesive layer of the polyethylene composite pipe is weakened and thus fails.

[0005] In the prior art, there is only a method for verifying the shear strength of the steel wire and the bonding resin raw material, and there is no mention of the detection method for the shear strength of the steel wire and the bonding resin in the finished composite pipe, and it is impossible to verify the steel wire mesh. Testing method for the bonding strength between the steel wire layer and the adhesive resin layer in the finished skeleton polyethylene composite pipe

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