What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Applications Automotive industry -- cars, trucks, buses, compressors, construction machinery, wind power equipment, fasteners, fasteners, agricultural machinery, foundry industry, drilling equipment, shipbuilding industry, military mining equipment, oil drilling rigs (onshore or offshore), public utilities, rail transit drives System metallurgical equipment rock hammer
(1) The screw-in performance test is to screw the self-tapping locking screw sample into the test plate until one complete thread completely passes the test without breaking. (2) The destructive torque test is to clamp the stem of the self-tapping locking screw specimen in a thread mold or other device that matches the screw thread, and uses a calibrated torque-measuring device to measure the screw. Torque is applied until fracture, which should not occur in the clamped threaded portion. (3) Carry out a tensile test on the screw sample to check the minimum tensile load for failure. The fracture should be within the length of the rod or the unthreaded thread, and should not occur at the junction of the nail head and the rod. Before the sample breaks, it should be It can reach the minimum tensile load specified by the corresponding performance class. (4) Hydrogen embrittlement is a problem that must be strictly paid attention to in the surface treatment process of self-tapping locking screws. In the pickling process, the screw is stirred in dilute hydrochloric acid, and the amount of hydrogen absorbed by the pickling steel increases linearly with the square root of time and reaches the saturation value. Less than 100%, a large number of hydrogen atoms will be produced, which will be attached to the surface of the screw, resulting in hydrogen infiltration, and the steel will become brittle due to the absorption of hydrogen. The self-tapping locking screw takes 6~8h to drive hydrogen, and the temperature is 160~200℃ (phosphating) and 200~240℃ (electroplating). However, in the production process, the hydrogen drive time should be determined according to many production conditions such as core hardness, surface roughness, electroplating time, coating thickness, pickling time, and acid concentration. It is best to do it before passivation and just after electroplating.
All kinds of industrial equipment need to be installed on the equipment foundation for work and operation. The equipment foundation includes concrete foundation, steel base, steel platform, steel frame and other forms.
Regardless of stainless steel plate or heat-resistant steel plate, austenitic steel plates have the best comprehensive properties, with sufficient strength, excellent plasticity and low hardness, which is one of the reasons why they are widely used. Austenitic stainless steel is similar to most other metal materials, its tensile strength, yield strength and hardness increase with the decrease of temperature; plasticity decreases with the decrease of temperature. Its tensile strength increases uniformly in the temperature range of 15~80°C. More importantly: as the temperature decreases, the impact toughness of stainless steel screws decreases slowly, and there is no brittle transition temperature. Therefore, stainless steel can maintain sufficient plasticity and toughness at low temperature.
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