What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
slotted screw comprises a screw rod, one end of the screw rod is connected to the middle of the bottom surface of the screw head, the side wall of one end of the screw rod away from the screw head is provided with a screw slot in the vertical direction, the screw The bottom surface of the head is in seamless contact with the top surface of the buffer wear-resistant pad, the buffer wear-resistant pad is connected with the screw rod by threads, and the buffer wear-resistant pad is provided with several shock-absorbing holes equally spaced along the circumference.
The spring washer can prevent loosening and increase the pre-tightening force, while the flat washer does not have this function. It can be used to increase the tightening contact area, prevent the friction between the bolt and the workpiece, and protect the surface of the connector to prevent bolts. The surface of the workpiece is scratched when the nut is tightened. However, for some important connections, such as places that rely mainly on compression to generate frictional force to transmit power, spring pads cannot be used, and the rigidity of the connection is reduced, which is prone to accidents. Spring washers can be omitted. When the strength of the connected parts is low, use flat washers or flange bolts to increase the contact area. When there is vibration, pulse, and the temperature of the medium fluctuates greatly, spring washers must be used.
In general, the size, mechanical properties and working performance requirements of self-tapping screws have the following standards: 1. Self-tapping screw size standard ASME B18.6.3 2010 standard not only introduces the dimensions of slotted and cross-recessed self-tapping screws and metal drive screws, but also includes the mechanical properties and work performance requirements of carbon steel self-tapping screws. The appendix gives instructions for measuring the various dimensions and application guidance on clamping lengths and test apertures. 2. Self-tapping screw performance standards (including mechanical properties and work performance): (1) SAE J933: Introduces the mechanical performance and work performance requirements of carbon steel ordinary self-tapping screws and white-cut self-tapping screws. The requirements for selection of raw materials, heat treatment, depth of carburized layer, surface hardness, and core hardness are further specified. (2) SAE J81: The mechanical properties and working performance of self-extrusion self-tapping screws (self-tapping locking screws) are introduced. (3) SAE J78: The mechanical properties and working properties of self-drilling and self-tapping screws are introduced. (4) IFl-113: The mechanical properties and working properties of self-drilling and self-tapping screws are introduced. (5) ASTM C1513: Introduces the mechanical properties and performance requirements of carbon steel self-tapping screws. For other special types of self-tapping screws, there is no corresponding national or industrial standard, and no data for self-tapping screws made of other metal materials other than carbon steel have been recognized. For technical data on these self-tapping screws, you can check with the manufacturer.
In order to tighten the fastener, the holding element of the tightening tool can hold the washer in engagement with the bolt to prevent the washer from rotating while allowing the rotating element of the tightening tool to rotate the nut. Such tools are disclosed, for example, in Application Serial Nos. 0/010377 and 10/120343. In this structure, since the same size washer cannot be arranged on the driving part and the fixing part, the driving part is made into the inner socket of the nut, and the fixing part is made into the outer socket of the washer, so , regular hexagonal nuts cannot be used. This is because, when just tightening the nut, the outer cavity cannot be removed since the hexagonal surface of the nut will not align with the hexagonal surface of the washer. Due to the larger diameter of the fastener formed as the outer cavity, side clearance problems may arise, thus increasing the cross-sectional profile of the hexagonal surface of the washer, which is undesirable.
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