Flange rectangular thread

Flange rectangular thread

The tooth profile is square, the profile angle α = 0°, the tooth thickness is half of the thread pitch, the equivalent friction coefficient is small, the efficiency is high, but the root strength is low, the axial clearance caused by thread wear is difficult to compensate, and the alignment accuracy Low and difficult to finish, therefore, this kind of thread has been seldom used

Flange cylindrical pipe thread

The tooth profile angle α = 55°, the tooth crest is arc-shaped, there is no radial gap between the screw threads, and the tightness is good. The nominal diameter is the nominal diameter of the pipe (Figure 9-8c). It is widely used in water, gas, Lubrication and other pipeline systems are connected

The tooth profile angle α = 55°, in inches, and the pitch is expressed in the number of teeth per inch, and there are also coarse and fine teeth. Mainly used in Britain, the United States and other countries, and generally only used in repairs in China.

Ordinary flange thread:

In the national standard, triangular metric thread with profile angle α = 60° is called ordinary thread, and the major diameter d is the nominal diameter. The same nominal diameter can have threads with multiple pitches, of which the largest pitch is called coarse thread, the others are called fine thread, and coarse thread is the most widely used. The small diameter of the fine thread is large and the angle of rise is small, so it has good self-locking performance and high strength, but it is not wear-resistant and easy to slide. It is suitable for thin-walled parts, dynamic load connection and fine adjustment mechanism adjustment.

Installation of flange bolt set

1) The shape of the parts at the joint surface should be as simple as possible, preferably square, round or rectangular. The number of bolts on the same circumference should be 4, 6, 8, 12, etc., to facilitate indexing during processing. The centroid of the bolt group should be coincident with the centroid of the joint surface of the part. It is better to have two symmetrical axes perpendicular to each other to facilitate processing and calculation. The middle of the joint surface is often hollowed out to reduce the amount of joint surface processing and joint surface. The effect of flatness can also increase the connection stiffness.
2) For bolt groups subjected to torque, the bolts should be far away from the axis of symmetry to reduce the force on the bolts.
3) For bolt groups subjected to lateral force, the number of bolts arranged along the direction of force should not exceed 6-8, so as to avoid serious uneven force on each bolt.
4) The shape, size, material, etc. of the fasteners used in the same bolt group should be consistent to facilitate processing and assembly.
5) When assembling the threaded connection, the tool should have enough operating space, and a certain spanner space size should be guaranteed.

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