Test method for clearance and rotational flexibility of pipe fittings
The measurement of the radial clearance of the whole tube is not easy, the measuring force causes the ring and the rolling body and the contact place to produce the elastic deformation, the deformation amount is the many factors that cause the measurement error, it is related to the measuring force, the contact state and the position of the rolling body.
Tube rotation flexibility generally in the horizontal position check, usually the inner ring fixed (or holding the inner ring), with the hand to rotate the outer ring, check the tube rotation when there is abnormal sound and block phenomenon. Generally speaking, the length of the pipe is long, the time to stop is slow, the flexibility is good. Conversely, the rotation time is short, stops suddenly, the flexibility is not good. Because of the different structure and size of the tube, the rotational flexibility should be different. For example, single row centripetal ball fittings, single row centripetal thrust ball fittings, because the contact area between the rolling body and the ring is small, these pipe fittings rotate relatively brisk, the double row centripetal spherical pipe and the thrust roller fitting, because the rolling body and the raceway contact area is larger, the outer ring’s weight is small, in checks its rotational flexibility, although adds certain load, but its brisk degree is still inferior to the single row centripetal ball fitting. For oversize pipe fittings, when rotating it, there should be no stuck phenomenon, and the rotating sound is generally not checked.
For tapered bore pipe fittings, the following methods can be used to check the rotational flexibility of pipe fittings, as follows:
The taper hole fitting is pressed into the mandrel until a certain radial preload is added, and when the A rings are rotated, the rolling body should be rotated. If the rolling body is sliding instead of rotating, it means that the ring has too much geometry defects or that the rolling body size is uneven, and the rotational flexibility of the pipe is poor.
