What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
With the continuous improvement of road facilities, guardrails are set up in the middle of the roads in most cities at the separation of the upper and lower lanes. At the same time, guardrails are also set up between the motor vehicle lane and the non-motor vehicle lane. The bottom of the guardrail column is set with a base, and the base is usually made of If the steel nail is fixed, the deformation hole should be drilled on the asphalt road first, and then the steel nail should be knocked into the deformation hole. Because the outer wall of the steel nail is cylindrical, the friction force on the ground is small, and the guardrail is affected by the deformation. When the external impact force occurs, the steel nails are easily detached from the asphalt road, making the road guardrail lose its fixation. In some places, expansion screws are used to fix the railings, but during the tightening process of the expansion screws, the expansion pieces are opened by the force of the ejector rod, and the opening angle is small. Limited, the railing will still fall down when subjected to a large impact. Therefore, it is necessary to design a special screw for fixing the railing on the asphalt road.
A rivet is a part that uses its own deformation or interference to connect the riveted parts in riveting. With the continuous progress and development of science, rivets have been used in many occasions because of their convenient use and reliable connection. The rivet includes a nail head and a stem. The traditional processing mold for the rivet head includes a base, and a nail head forming part is arranged on the base. However, due to the limited service life of the mold, the processing mold of this structure is replaced. It needs to be replaced together with the base, which is a waste of material, which increases the production cost, and the rivet itself is relatively cheap, so this reduces the profit of the enterprise.
Among the mold parts used in the can manufacturing industry, some product inner holes need to be processed with stop slots after heat treatment. The inner hole diameter of the product is φ28mm, the width of the slot is about 1.3mm, and the size and shape of the outer end face of the slot adjacent to the orifice The tolerance requirements are very strict, generally within the range of 0.02mm. If the CNC machine tool is used for cutting, the blade loss is very serious because the groove width is too narrow; if the inner hole grinding is used, there is no ready-made grinder and grinding wheel.
On the other hand, especially in the aerospace field, the requirements for the sealing effect of screws are extremely strict, and the traditional screws are directly tightened when screwed into the workpiece or equipment, and the sealing effect is determined by the tightness, but due to the machining error of the workpiece or equipment The direct butt seal between the seals is difficult to achieve.
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