What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The flat screw mainly includes a rotating part and a screw locking part, wherein the rotating part and the screw locking part are respectively flat-shaped structures; At least two sides of the screw lock portion are respectively provided with tooth rows, and the two tooth rows are mutually dislocated, so that the screw lock portion can be locked in a pre-formed screw hole in the workpiece.
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.
Mine trucks are required for underground construction and coal transportation. With the vigorous development of energy, the output of coal has increased significantly, and the demand for mine trucks has increased. The axle card is an important part of the mine car. Its shape is irregular, and the blank is a casting. It needs to be finished on the semicircular surface whose upper center is matched with the mine car axle. At present, the mine truck axle card is generally processed by a milling machine, which has the problem of low efficiency.
Inspection method There are two types of screw surface inspection, one is the inspection before the screw is produced and not plated, and the other is the inspection after the screw is plated, that is to say, after the screw is hardened and the surface of the screw is treated. . After the screws are produced and before electroplating, we inspect the screws in various aspects such as size and tolerance. See if there are national standards or customer requirements. After the surface treatment of the screws, we will inspect the plated screws, mainly to check the color of the plating and whether there are any broken screws. In this way, when we deliver screw goods to customers, customers can successfully pass the customs when they receive the goods. Inspection of screws after treatment: 1. Appearance quality requirements The inspection of the appearance of screws is carried out from the aspects of appearance, electroplating layer and so on. Second, the inspection of the thickness of the screw coating 1. The measuring tool method uses a micrometer, a vernier caliper, a plug gauge, etc. 2. Magnetic method The magnetic method is used to measure the thickness of the coating layer, which is a non-destructive measurement of the non-magnetic coating layer on the magnetic substrate with a magnetic thickness gauge. 3. Microscopy Microscopy is called metallographic method, which is to magnify the etched fasteners on a metallographic microscope with a micrometer eyepiece to measure the thickness of the coating on the section. 4. Timing flow method The timing flow method uses a solution that can dissolve the coating to flow on the local surface of the coating, and calculates the thickness of the coating according to the time required for the local coating to dissolve. There are also coating drop method, anodic dissolution Coulomb method, etc. 3. Inspection of the adhesion strength of the screw coating There are many methods for evaluating the adhesion between the coating and the base metal, usually the following. 1. Friction polishing test; 2. File method test; 3. Scratch method; 4. Bending test; 5. Thermal shock test; 6. Extrusion method. 4. Inspection of corrosion resistance of screw coatings The corrosion resistance inspection methods of coatings include: atmospheric exposure test; neutral salt spray test (NSS test); acetate salt spray test (ASS test), copper accelerated acetate salt spray test (CASS) test); and corrosion paste corrosion test (CORR test) and solution spot corrosion test; immersion test, inter-dipping corrosion test, etc.
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