What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Usually, the pumped storage unit adjusts the opening of the guide vane through the movable guide vane to control the power generation output and the pumping head of the unit. The torque of the guide vane rotation depends on the relay to act on the control ring, and the torque is transmitted to the guide vane rotating shaft through the connecting rod and the arm. The torque transmission between the crank arm and the rotating shaft all acts on the pin located between them. When the unit is overhauled, it is necessary to remove the pin between the arm and the rotating shaft of the guide vane in advance when it comes to the replacement of the guide vane. However, due to the special position of the pin and the limited inspection space, the conventional method is not only time-consuming and laborious, but also has the risk of damaging the pin. Maintenance work brings inconvenience.
The self-tapping locking screw is composed of three parts: the head, the stem and the end of the stem from beginning to end. The composition of each self-tapping screw has four major elements: head shape, wrenching method, thread type, and end type. Head Shapes - Head shapes come in all shapes and sizes. There are round head (semi-round head), oblate head, round head flange (with pad), oblate head flange (with pad), pan head, pan head flange (with pad), countersunk head, semi-countersunk head, Cylinder head, spherical cylinder head, horn head, hexagonal head, hexagonal flange head, hexagonal flange (with gasket), etc. Wrench Styles - There are various ways of wrenching. External wrench: hexagonal, hexagonal flange, hexagonal flange, hexagonal flower shape, etc.; internal wrench: slotted, cross groove H type (Phillips), cross groove Z type (Pozidriv), cross groove F type (Frearson) , Square groove (Scrulox), compound groove, internal spline, internal hexagon flower (plum groove), internal triangle, internal hexagon, internal 12-angle, clutch groove, six-blade groove, high torque cross groove and so on. Thread Types - There are many types of threads. There are self-tapping threads (wide thread), machine threads, drywall screw threads, fiberboard screw threads, and some other special threads. In addition, the thread can be divided into single lead (single head), double lead (double head), multi-lead (multiple head) and high and low thread double head thread. End type - The end type mainly includes saw end and flat end. However, according to the function of use, grooves, grooves, incisions or parts with a cutting function can be processed. In some standards, the same saw end or flat end, there are different forms. There are various changes in the head shape, wrenching method, thread type and shank end type of self-tapping screws. They can be combined with each other to show many different products belonging to the category of self-tapping screws.
Stamping die is a special process equipment for processing materials into parts in cold stamping processing, called cold stamping die. Stamping is to use the die installed on the press to apply pressure to the material at room temperature to make it produce Separation or plastic deformation to obtain the required parts of a pressure processing method, the technology generally used is to make corresponding holes and punches on the template, this method cannot meet the requirements for small batches and short delivery time products , the relative cost is relatively high, so a rivet die structure is required to improve the above problems.
The anti-theft screw of this structure has two disadvantages. One is that the polygonal block moves up and down in the polygonal hole, and the polygonal hole in the connecting piece and the polygonal hole on the threaded part have no limit structure. Because of the polygonal structure, the two If the polygonal holes of the parts cannot be aligned, dislocation occurs, and any edge may block the up and down movement of the polygonal block, which is very unsmooth during use. The second is that the shell of the lock cylinder and the hexagonal part are connected by pins, and the pins are exposed on the hexagonal parts, which are easily damaged and leave opportunities for theft; once the pin is pried off, the lock cylinder will be taken out, and the entire anti-theft screw will be lost. and the pin fixation is sometimes unstable, which is detrimental to theft.
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