What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The isolating switch in the substation has a large workload for maintenance. The transmission parts such as the isolating switch connecting rod are mostly connected by cylindrical pins. The shaft-pin fit is generally 1mm, which is tight. If the cylindrical pin is disassembled during the maintenance process, it is often due to corrosion and mechanical deformation. It is difficult to proceed smoothly for other reasons, and if the working environment is a small space, it is more difficult to disassemble. In traditional operations, grinding, hard prying, or beating with a hand hammer are often used to disassemble, which will further deform the pins, and when the space is small, it is difficult to use tools such as hand hammers. solve.
The marking format of the thread mark is: Thread code - thread tolerance zone code (pitch diameter, top diameter) - screw length l) Tolerance zone code is represented by numbers plus letters (inner thread with uppercase letters, external thread with lowercase letters) , such as 7H, 6g, etc., it should be specially pointed out that 7H, 6g, etc. represent thread tolerance, while H7, g6 represent cylinder tolerance code. 2) The length of rotation is specified as short (represented by S), medium (represented by N), and long (represented by L). In general, the thread engagement length is not marked, and the thread tolerance zone is determined by the medium engagement length (N). If necessary, add the screw length code S or L, such as M20-5g6g-L. When special needs are required, the value of the screwing length can be indicated, such as M20-5g6g-30.
The utility model proposes an installation structure which adopts a T-shaped bolt to cooperate with a channel, which includes a bolt head, an installation channel, a nut and a washer. The upper end of the screw rod is provided with a screw head, the two side walls of the bolt head are respectively provided with an arc surface, the two ends of the bolt head are provided with protrusions, and the interior of the installation channel is provided with an inner cavity, There is an opening above the installation channel, the bolt head is installed in the inner cavity, the nut is installed on the screw, the nut is located above the installation channel, and the gasket is installed on the installation channel and the nut between.
leak-proof combined gasket relates to a gasket and solves the problem of short service life of the existing gasket. The combined gasket comprises: an O-shaped sealing ring, which is an annular sealing ring with an outer diameter of D and an inner diameter of E. The section diameter is A; the steel outer ring is a steel flat annular outer ring, which is sleeved on the outer surface of the O-ring, the inner diameter is F, and F=D, the thickness is B, B=0.785A ;The steel inner ring is a steel flat annular inner ring, embedded in the inner surface of the O-ring, the outer diameter is G, and G=E; the thickness is C, and C=B. When the O-ring in the combined washer is pressed by the bolt for sealing, it is positioned between the steel outer ring and the steel inner ring, and is protected by both of them, so that the tightening torque of the bolt can be reduced at least Double the sealing performance without reducing the sealing performance, extending the service life of the thread and reducing the production cost.
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