Spring washer mechanical performance requirements
The function of the spring washer is to prevent looseness between the connected parts. The load that a head product (bolt, screw) is subjected to is distributed over a relatively large area and provides a stiffened bearing surface.
Material and hardness
1. Hardness: In order to test the hardness of the gasket, the edges should be trimmed, grounded, etc., so that the ruler may be flat and parallel to ensure the accuracy of the detected value. In addition, the decarburized layer and the plating layer on the surface should be effectively removed. Care should be taken not to allow the temperature of the gasket surface to exceed 250 o F. The corresponding relationship between the relevant material and the hardness of the gasket is shown in the figure below.
2. Decarburization: The limit dimensions of the decarburization layer of carbon steel and boron steel alloy steel spring washers are as specified in Table 1.
Process
1. Surface treatment: If the user does not have other requirements, the gasket should be supplied with no surface and no coating. If the buyer requires corrosion protection of the gasket, the gasket should be plated or coated. Thicker coated surface protection is not recommended for gaskets with a nominal value of less than 1/4 in.
2. Brittleness: Carbon steel and boron steel gaskets may cause hydrogen embrittlement after plating, and corresponding measures should be taken to prevent hydrogen embrittlement. After the plating, the gasket should be flattened for more than 48 hours to observe whether there is brittle fracture.
Torque test (toughness test)
Clamp the spring washer on the bench vise. The washer opening should be horizontal. The upper half of the washer is not 1/2 of the entire outer diameter of the clamp. The clamp is then clamped to the upper half of the washer. The direction shown in the figure below is reversed. For carbon steel, boron steel and alloy steel washers twisted to 90 o , the washer should not show signs of breakage when the stainless steel washer is twisted to 45 o .
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