What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
M4 grounding screw used to fix the grounding wire on household appliances and other equipment, the stud is cylindrical, and the thread is perpendicular to the end (section) surface. However, the screw holes on the equipment all have tapping guide grooves for sinking and guiding due to the manufacturing process requirements. When fixing the ground wire, if the screw is not positioned accurately (the screw is inclined), the screw is pressed down hard, which is easy to cause the screw and the screw. The screw hole bites the teeth, and after biting the teeth, it is easy to cause the screw to loosen or fall off, posing a safety hazard.
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.
In order to solve this technical problem, Yueluo Company provides an adjusting nut, which includes a bearing unit, a thrust washer, an adjusting nut and a snap ring. The inside of the adjusting nut is an internal thread structure, and one end of the internal thread structure is provided with Ring groove, the snap ring is pressed into the ring groove with interference, and is rigidly connected with the adjusting nut without relative movement; the bearing unit is supported on the shaft, and the thrust washer is in plane fit with the bearing unit; the adjusting nut and the shaft are threadedly connected , Fit with the thrust washer plane, the inner diameter of the snap ring and the thread of the shaft are in interference fit.
The main purpose of the embedded nut is to replace the direct opening of screw holes on the injection molded parts, so as to improve the strength of the screw holes of the injection molded parts. Referring to FIG. 1 , in order to lock the workpiece 3 ′ on the injection molded part 2 ′, the screw 5 ′ passes through the through hole on the workpiece 3 ′ and is screwed into the screw hole of the embedded nut 1 ′ to fix the workpiece 3 ′. The embedding between the embedded nut 1' and the injection-molded part 2' generally includes two ways. One is to heat the embedded nut 1' and then insert it into the injection-molded part 2' by hot pressing; the other is to insert the embedded nut into the injection-molded part 2'. 1' and the injection part 2' are integrally injection-molded. In order to ensure the bonding strength between the inner nut 1' and the injection molded part 2', knurling is provided on the outer peripheral surface of the inner nut 1'.
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