What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
When used for the connection and fixation of doors, windows, cabinets, etc. involving hinges, the traditional screw fastening method is usually used, and the screws are directly driven into the screw holes of the connected parts, and the screw end caps are directly exposed, which not only affects the connected parts. Moreover, the end caps of the screws exposed for a long time are easy to rust, and there are burrs in the end processing of the general screws. When used for fastening connections, the end caps of the screws are easy to scratch people, which affects the appearance and is not safe.
The drawing process has two purposes, one is to modify the size of the raw materials; the other is to obtain basic mechanical properties of the fasteners through deformation and strengthening. For medium carbon steel, medium carbon alloy steel also has another purpose, that is, to make the wire rod. The flaky cementite obtained after controlled cooling is cracked as much as possible during the drawing process to prepare for the subsequent spheroidization (softening) annealing to obtain granular cementite. However, some manufacturers arbitrarily reduce the drawing in order to reduce costs. The excessive reduction rate increases the work hardening tendency of the wire rod, which directly affects the cold heading performance of the wire rod. If the distribution of the reduction ratio of each pass is not appropriate, it will also cause torsional cracks in the wire rod during the drawing process. In addition, if the lubrication is not good during the drawing process, it can also cause regular transverse cracks in the cold drawn wire rod. The tangential direction of the wire rod and the wire drawing die is not concentric at the same time when the wire rod is rolled out of the die, which will cause the wear of the unilateral hole pattern of the wire drawing die to aggravate, make the inner hole out of round, and cause uneven drawing deformation in the circumferential direction of the wire. The roundness of the steel wire is out of tolerance, and the cross-sectional stress of the steel wire is not uniform during the cold heading process, which affects the cold heading pass rate. During the drawing process of the wire rod, the excessive surface reduction ratio will deteriorate the surface quality of the steel wire, while the too low surface reduction ratio is not conducive to the crushing of the flaky cementite, and it is difficult to obtain as much granular cementite as possible. , that is, the spheroidization rate of cementite is low, which is extremely unfavorable to the cold heading performance of the steel wire. For the bar and wire rod produced by the drawing method, the partial surface reduction rate is directly controlled within the range of 10%-15%.
The quality of the combination screw should start with the screw wire of the combination screw manufacturer. The wire of the screw is the first hurdle to determine the quality of the combination screw. Even if the wire is not good, even if the production equipment is advanced and the staff is skilled, it is impossible to produce high-quality combination screws. In the second look at the quality of the combination screw products, from the overall aesthetics of the combination screw. A combined screw is formed, the size of the screw head, the superior appearance of the flat washer, whether the screw thread can pass the stop gauge, etc. These are all things that need to be detected. A good combination screw, its overall standard can meet the national standard requirements, or customer requirements. Finally, the quality of the combination screw product is seen from the color of the plating. Of course, the iron combination screw needs to be plated, but the stainless steel combination screw does not need it. Some of them are passivation at most, in order to increase the salt spray resistance of stainless steel combination screws. In the electroplating color of the combination screw, some of them are not well controlled, which will produce a great color difference. That doesn't look good.
In order to achieve the above purpose, Guangdong Yueluo Hardware Industry Co., Ltd. provides the following technical solutions: self-expanding semi-solid installation rivets, used for connecting and perforating two or more units of parts, including top core and rivet body, characterized in that : The top core lock slot opened on the concentric sheath along the longitudinal direction is snapped into and screwed and fixed in the concentric sheath, the top core extends downward into the top core rotary sleeve, the concentric sheath The sleeve is connected with the upper sealing sleeve of the lower body and is connected with the longitudinal axis, a hollow body is arranged below the rivet body, a joint is installed under the hollow body, and a supporting foot is connected to the joint, and the supporting foot and the turning The folding clips are staggered and distributed, the folding clips are concave-convex inclined surfaces, and the supporting feet are slidably connected with the folding clips.
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