The inch thread is the thread size marked in inch. According to the shape, it is divided into two types: cylindrical and conical; according to the tooth angle, it is divided into two types: 55° and 60°. The 1/4, 1/2, 1/8 marks in the thread refer to the diameter of the thread size in inches. One inch equals 8 cents, 1/4 inch equals 2 cents, and so on.
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.
At present, the automatic nailing device on the domestic market lacks the restraint and arrangement of the rivets when they are out of the nailing device, which makes the rivets irregular and uncontrollable after the automatic nailing is completed, which has adverse effects on on-site use and maintenance, and is unstable. .
However, although the existing screw can meet the function of connecting and tightening objects, its structure includes a head and a threaded rod connected with the head. Since it only has one threaded rod, it does not have a two-way connection function and cannot be satisfied with the Some special use requirements bring inconvenience to use.
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.
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