What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Existing wood screws are composed of a threaded portion with a tapered angle and arranged along a tapered stem and a screw head. The head of the screw can be a countersunk head, hemispherical, or other shapes, and the head of the screw has a groove that fits with the tool, a word groove, and a concave cross groove. The taper angle of existing wood screws is either 45 degrees or 60 degrees, and the front end of the taper angle is a pointed point formed by a rotating thread. The existing wood screws have the following three deficiencies in use. Because the taper angle is 45 degrees or 60 degrees, and the thread angle is 71 degrees, the resistance when entering the material is relatively large, so the existing wood screws are manually screwed. It is difficult to screw in, especially when it is used for hardwood materials, and it often happens that the groove of the screw head is screwed out; A large lateral moment will be formed when the screw is screwed, which is prone to the problem of deviation from the position; in addition, because the existing screw is tapered, it will be subjected to both radial force and axial force when entering the material, and its stress state It is more complicated, so it is easy to cause the cracked wood material to burst, and even cause the material to have longitudinal cracks and be unusable.
Dowels are made on the steering seat on the ball head of the car, and the rollers are assembled to the steering seat through the dowels. The prior art is manual driving of the pins, and the position of the pins is inaccurate when driving the pins, the labor intensity is high, the efficiency is low, and the quality of the steering seat is also affected. Therefore, it is necessary to design an automatic pin-driving mechanism to drive the pins into the steering seat. .
screw is a tool that uses the physical and mathematical principles of the circular rotation and rotation of the oblique surface of an object to gradually fasten the mechanism of the utensil. A screw is a common term for fasteners, an everyday colloquial language. Screws are indispensable industrial necessities in daily life: tiny screws used in cameras, glasses, clocks, electronics, etc.; general screws in televisions, electrical products, musical instruments, furniture, etc.; as for engineering, construction, and bridges, large screws are used. Screws and nuts; transportation equipment, airplanes, trams, automobiles, etc. are used together with large and small screws. Screws have important tasks in industry. As long as there is industry on earth, the function of screws will always be important. The screw is a common invention in people's production and life for thousands of years. According to the application field, it is a great invention of human beings. At present, the head of the screw on the market is generally punched with a cross groove or a word groove, which is used for tightening or Remove the screw, but the cross slot or the slot is easy to deform after a long time, it is difficult to disassemble it with tools, and sometimes the tool of the corresponding size cannot be found and the disassembly cannot be carried out, and the disassembly is relatively inconvenient.
The diameter, length and quantity of the stud bolts shall meet the requirements, and the type and material of the stud bolts shall be determined by the grade. There are two types of commonly used stud bolts (also known as full-threaded studs). The thread is divided into two types: coarse thread and fine thread. The coarse thread ordinary thread is expressed by M and the nominal diameter, and the fine thread ordinary thread is expressed by M and the nominal diameter × pitch. The fastener standard stipulates that M36 bolts use coarse thread, M36 and above diameters can use fine thread, and the pitch is 3. bm=1d studs are generally used for the connection between two steel connected parts; bm=1.25d and bm=1.5d studs are generally used between cast iron connected parts and steel connected parts The connection between the two; bm=2d double-ended stud is generally used for the connection between the aluminum alloy to be connected and the steel to be connected. The former connector has internal threaded holes, and the latter connector has through holes. The threads at both ends of the equal-length studs need to be matched with nuts and washers, and are used for two connected parts with through holes. One end of the welding stud is welded on the surface of the connected piece, and the other end (threaded end) passes through the connected piece with a through hole, and then the washer is put on, and the nut is screwed on, so that the two connected pieces are connected as a whole.
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