What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
structure for concealing installation screws, comprising a locking piece, a driving piece, a bottom plate, a blocking cover and a handle head, the lower ends of the two locking pieces are provided with positioning holes, and the locking pieces pass through the positioning holes and the locking piece positioning posts on the base The occlusal and fixed, the middle of the two locking pieces is provided with a protruding point, the movable groove of the driving piece corresponds to the protruding points of the three locking pieces for fixing, the riveting point holes and screw holes of the bottom plate and the riveting points of the base The position that matches the screw holes and is fixed by screws, the blocking cover is directly inserted into the bottom plate, and the blocking cover is fixed by the rotating drive piece, the handle head is inserted into the base, and the slot of the handle head moves to the locking piece at the locking piece Lock the handle.
rivet assembly device is provided with a base, the middle of the base is provided with a vertical groove, the bottom wall of the vertical groove extends forward and a horizontal convex block is suspended; the top surface of the convex block is fixed with a vertical rivet Needle and a guide column, the column body of the guide column is covered with a return spring; a downwardly open sliding block is mounted on the convex block, and the upper ends of the rivet needle and the guide column respectively protrude into the sliding block on the top wall of the sliding block. In the riveting pin hole and the guide hole, the inner wall of the riveting pin hole is provided with a large upper and a lower small horizontal step; the upper part of the bottom wall of the vertical groove is provided with a guiding limit rib. Guangdong Yueluo Hardware Industrial Co., Ltd. sets the rivet needle under the workpiece, and uses the upper die punch to press down the workpiece, and the rivet needle completes the operation of the rivet, omitting the operator to turn over and carry the rivet terminal board, thus effectively avoiding the rivet from The phenomenon that the rivet hole comes out. In addition, during operation, the workpiece is placed on the top surface of the slider, and the workpiece guide limit ribs and guide columns are used as shafts and radial limiters respectively. The riveting quality is good, and the purpose of saving time and labor and high efficiency is achieved.
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%.
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
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