What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The global economy continues to slump and overseas export trade is sluggish. Many fastener companies at home and abroad are facing severe tests. Accelerating economic transformation and structural upgrading is imminent, and developing overseas markets is undoubtedly an important way out for the development of the current fastener industry. From the fourth quarter of 2011 to the first half of 2012, affected by the objective environment, the development speed of the fastener industry may slow down, but from the third quarter of 2012, with the policy in place, the convening of the 18th National Congress of The upcoming series of development policies, etc., can promote the further development of the industry. And we must insist on innovation and adjustment and transformation, we must continue to rely closely on key industries such as automobiles, new energy, aerospace, shipbuilding, urban transportation, IT, electronic appliances, construction, etc., accelerate the optimization and upgrading of fastener products, and promote fasteners. The whole industry develops healthily and steadily. The global fastener market size exceeds 50 billion US dollars, and China's total fastener production in 2012 is also expected to reach about 6.8 million tons. However, compared with the manufacturing powerhouses such as the United States and Japan, there is still a big gap in my country's fastener industry.
screw suitable for a variety of tools is a single-structure threaded part, including a screw body and a screw head. The outer surface of the screw body is processed with an external thread 1, and the outer side of the screw head is formed by six screw heads. Prismatic, the top surface of each edge of the outer hexagonal prism is a boss, between each boss is an end face groove 4, and the middle of each boss is provided with an end face hole 3; the inner side of the screw head is formed by six screw heads. The side surface 5 forms an inner hexagonal prism hole, and the bottom of the inner hexagonal prism hole is processed with a cross groove 12 .
At present, drum brakes are usually used for rear brakes of automobiles, and pump parts assemblies are widely used. The traditional assembly method is to use tools such as screwdrivers and retaining ring pliers for assembly. The disadvantage is that the assembly efficiency is low, the accuracy is average, and assembly quality problems are prone to occur, which affects the performance of the product assembly. Now take the brake wheel cylinder assembly with automatic clearance adjustment mechanism produced by our factory as an example to illustrate the installation of the elastic retaining ring
Due to manufacturing and installation errors, the lamp head and its connecting part of the shadowless lamp will drift, which cannot be positioned at any position. Therefore, in the shadowless lamp, the damping force is usually provided by the damping screw to realize the positioning of the lamp cap and its connecting part. The damping screw needs to be able to provide a suitable damping force. The damping force should not be too small to meet the positioning requirements; at the same time, the damping force should not be too large to make the user feel comfortable when moving the lamp head and its connecting parts. In addition, within the normal life range, after the damping screw is worn, it should also be able to provide sufficient damping force to satisfy the positioning of the lamp cap and its connecting part. The damping screw is tightened by the thread, the top pressure disc spring is deformed, and the disc spring presses the friction end to generate frictional force, thereby providing an effective and lasting damping force. The damping force can be realized by adjusting the screw tightness. For the friction ends, there are certain requirements for wear resistance, certain self-lubrication, certain strength, hardness and toughness. At present, the friction end materials in the industry mainly include metals such as brass and tin bronze; non-metals such as nylon and POM. At present, the main disadvantage of the friction end of the damping screw is that it is easy to produce abnormal noise during the friction process for metal materials. For non-metallic materials, deformation is easy to occur and the strength is insufficient.
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