1. Subject content and scope of application

This standard specifies the test method for longitudinal bending stiffness of shoe hook.

This standard is applicable to the determination of longitudinal bending stiffness of shoe hook.

2 Principle

The heel end of the hook is fixed, and the front end of the hook is loaded to produce bending deformation. The bending deflection of the hook is measured to calculate the bending stiffness of the hook.

3 sample

3.1 the sample is made of hook core.

3.2 the sample shall be placed at room temperature for 0.5h before testing.

3.3 three hooks of the same specification shall be used for each grade of sample.

4 instruments

4.1 the hook stiffness tester consists of an adjustable hook rear end clamp, a hook front end clamp with weight and a dial indicator for measuring deflection (see Figure 1).

4.2 the back end clamp of hook center is composed of two claws, each claw is 32mm long, and there are two bars to clamp the hook center. The thickness of the bar is 6mm, and the front bar of the upper claw has a central groove, which is 6mm wide and 4mm deep. The front rib of the lower claw is an inclined plane with an angle of 10 ° to ensure the accuracy of the arm length.

4.3 the rear end fixture of the hook center can rotate around the horizontal axis, so as to adjust the clamping hook center to make the front and rear two clamping points on the same horizontal plane. The angle at which the fixture can be placed from the horizontal position shall not be less than 30 degrees.

4.4 the front-end clamp of hook center is composed of clamp and loading lug. The fixture consists of two flat splints with a thickness of 12mm. Each side of the lower splint is 6 mm wider than that of the upper splint, and there is a V-shaped groove on the upper surface of the lower splint across the flat along the central line of the flat.

4.5 the lower splint can support the lug of hanging weight. There are two horizontal coaxial pin shafts on both sides of the inner side of the lug, which are placed in the V-shaped groove on the upper surface of the lower splint. The axis of the pin shaft is within 1.0 mm higher than the upper surface of the lower splint. The surface roughness Ra of V-groove and pin is 0.8 μ M.

4.6 the dial indicator is used to measure the deflection of the hook center when it is forced and bent. Its position can be adjusted so that its measuring foot can be placed at the center of the upper surface of the loading lug.

4.7 the weight and dial indicator shall be periodically verified according to the national regulations.