What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The semicircular key is a kind of key, the upper surface is a plane, the lower surface is a semicircular arc surface, the two sides are parallel, commonly known as the crescent key. It is basically the same as the flat key connection method, but it is more convenient to manufacture and disassemble than the flat key, and is especially suitable for the connection between the tapered shaft and the hub. The half-round key transmits torque on the side, but the keyway is deep, which weakens the shaft greatly. Due to the deep keyway, the bottom of the keyway is easily deformed after the shaft is heat treated. Therefore, when the semicircular key and the keyway are assembled in a transitional fit relationship, the interference between the lower part of the semicircular key and the bottom of the keyway often occurs, resulting in difficult or impossible assembly. Assembly situation. In order to solve the above technical problems, the current method is to make the thickness of the semicircular key appropriately thin, so that the semicircular key and the keyway are clearance fit, which brings about a large gap between the upper part of the semicircular key and the keyway, and the semicircular key is in operation. Difficult to locate in the keyway, affecting smooth transmission.
Blind hole installation type rivet is a kind of rivet for single-sided riveting. When riveting, special riveting tools, such as pull riveting, rotary riveting, etc., are required. Blind hole installation type rivets are especially suitable for riveting occasions where it is inconvenient to use ordinary rivets to be riveted from both sides. At present, blind hole type blind rivets mainly include rivet blind rivets and blind blind rivets. Most blind rivets of blind hole type contain a lock ring, through which the core rod is locked into the nail sleeve, and there is a common lock ring. Risks of falling off, insufficient clamping force, etc., and the matching relationship of each sub-part in the processing process must be strictly coordinated to ensure the best installation effect; most of the screw-type blind rivets screw the thread through the driving nut to make the nail body or pipe The body is deformed to form a bulge, and the clamping force and anti-vibration ability after installation are much stronger than that of the rivet type, but there are also many sub-parts to drive the nut, mandrel, nail body, tube body, the processing process and the matching of each sub-part When the thickness of the interlayer is different, the fractured part of the core rod is not flush with the interlayer board. For the installation parts with high flatness requirements, air tools are often required to mill them flat.
(1) The screw-in performance test is to screw the self-tapping locking screw sample into the test plate until one complete thread completely passes the test without breaking. (2) The destructive torque test is to clamp the stem of the self-tapping locking screw specimen in a thread mold or other device that matches the screw thread, and uses a calibrated torque-measuring device to measure the screw. Torque is applied until fracture, which should not occur in the clamped threaded portion. (3) Carry out a tensile test on the screw sample to check the minimum tensile load for failure. The fracture should be within the length of the rod or the unthreaded thread, and should not occur at the junction of the nail head and the rod. Before the sample breaks, it should be It can reach the minimum tensile load specified by the corresponding performance class. (4) Hydrogen embrittlement is a problem that must be strictly paid attention to in the surface treatment process of self-tapping locking screws. In the pickling process, the screw is stirred in dilute hydrochloric acid, and the amount of hydrogen absorbed by the pickling steel increases linearly with the square root of time and reaches the saturation value. Less than 100%, a large number of hydrogen atoms will be produced, which will be attached to the surface of the screw, resulting in hydrogen infiltration, and the steel will become brittle due to the absorption of hydrogen. The self-tapping locking screw takes 6~8h to drive hydrogen, and the temperature is 160~200℃ (phosphating) and 200~240℃ (electroplating). However, in the production process, the hydrogen drive time should be determined according to many production conditions such as core hardness, surface roughness, electroplating time, coating thickness, pickling time, and acid concentration. It is best to do it before passivation and just after electroplating.
The circlip travel mechanism includes a travel cylinder and a travel plate connected with the push rod of the travel cylinder; the travel air cylinder can control the travel plate to be inserted into the circlip press-out and positioning mechanism, and the circlip lifting and tightening mechanism; the travel plate The surface of the device is provided with a groove for placing the circlip; the height of the groove is the height of one circlip.
The above content is uploaded by Yueluo or the Internet. If there is any copyright issue, please contact [email protected].
