What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
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.
Washers are common parts that are annular or annular after compression. The existing standard washers include flat washers, spring washers, serrated lock washers, saddle washers, etc. The end faces are mostly flat or flat after compression. , so it is in surface contact with the workpiece. Generally, after the two workpieces are locked by washers, bolts and nuts, the workpieces cannot move in any direction, so as to achieve the purpose of tightening the two workpieces. In actual production, some workpieces are still required to be properly translated in a certain direction after locking. In order to achieve this requirement, the usual practice is to open a waist-shaped hole on the workpiece that needs to be moved, and the zigzag-shaped bushing is fitted with a flat washer after passing through the waist-shaped hole, as shown in FIG. The edge of the hole is located in the space enclosed by the bushing and the flat washer, and a gap is formed between the workpiece and the bushing and the flat washer, so that even if the bolt passes through the flat washer, the bushing and the workpiece in turn, it is threaded and locked with the nut. tight, the workpiece can still translate along the length of its girdle hole. Obviously, this method can achieve the requirement of proper translation of the workpiece, but the following deficiencies can still be found in the actual assembly. First, before locking, the bushing, washer and workpiece are separated from each other, so it is more inconvenient to assemble; secondly, the lining is The separation structure of the sleeve and the gasket is inconvenient to manage, and the disassembled gasket and bushing are easy to lose and affect the use again.
As shown in Figures 1 and 2, Yueluo is an automatic locking screw. From bottom to top, there are screw head 1 with external thread, screw rod and nut 3. The screw rod is a hollow screw rod 2, and the hollow screw There are long holes 7 on both sides of the rod 2, the width of the long hole 7 is smaller than the inner diameter of the hollow screw rod 2, and a spring 4 is arranged in the inner cavity of the hollow screw rod 2, and the spring 4 is not smaller than the hollow screw rod 2 in the free extension state. The upper end of the spring 4 is provided with a plug 5, the distance between the two wings 6 of the plug 5 is greater than the diameter of the nut 3, and the two wings 6 of the plug 5 protrude out of the hollow screw rod 2 through the long hole 7. When using the Yueluo, you only need to compress the spring through the two wings, insert the U-shaped clip after the neutral position is exposed, and then release the two wings, the spring will automatically return and compress the U-shaped clip, which is easy to use, safe and reliable. Claim 6. An automatic locking screw, from bottom to top, is a screw head, a screw rod and a nut provided with an external thread, characterized in that the screw rod is a hollow screw rod, and both sides of the hollow screw rod are respectively provided with Long hole, the width of the long hole is smaller than the inner diameter of the hollow screw rod, the inner cavity of the hollow screw rod is provided with a spring, the upper end of the spring is provided with a plug, and the two wings of the plug protrude out of the hollow screw rod through the long hole.
The lifting ring screw should be made of 20 or 25 steel (GB699). The lifting ring screw must be forged as a whole. The forgings should be normalized and the oxide scale should be removed. The grain size of the finished product should not be lower than grade 5 (YB27-77). There must be over-burning, crack defects.
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