In actual production, the inner spherical surface of pneumatic ball valve shell parts is difficult to process due to its special location. Especially for parts with high machining accuracy requirements, in order to ensure the processing quality, it is necessary to develop reasonable processing technology and design special fixtures and tools. Taking the machining of pneumatic ball valve shell as an example, this paper introduces a simple and practical method for turning the inner ball surface and its tool design.

Analysis on the function of low-temperature axial rotary compensator to ensure construction quality
The function of the low-temperature axial compensator of the steam pipeline: mainly to ensure the safe operation of the pipeline, it has the following functions:
1. Compensate the axial, transverse and angular thermal deformation of absorption pipe.
2. Absorb equipment vibration and reduce the impact of equipment vibration on pipeline.
3. Absorb the deformation of pipeline caused by earthquake and ground subsidence.
2、 Does the compensator extend when cold or when hot?
When the medium in the pipeline is lower than 20 degrees, the pipeline shrinks under the influence of temperature, and then the compensator extends. When the medium is above 20 degrees, the pipeline will shrink and extend, and the compensator will shrink. When the medium is maintained at 20 °, the compensator is maintained at the original position. The steam pipe will shrink and stretch after being heated. If this local elongation is not effectively absorbed, the pipe support will be damaged due to thrust, and in serious cases, the pipe will fall apart. Low temperature axial type compensator for pipeline is used to absorb pipeline shrinkage. Seen from the surface, when the pipeline is hot, the pipeline compensator is contracted, and when the rotary compensator is cold, it is extended.
1. The construction quality of directly buried steam pipeline is extremely important. It is necessary to strictly control each consumption process, strictly check the quality, and implement according to the design requirements, especially the joint insulation construction. It is necessary to strictly control and check one by one to ensure the construction quality; 2. Necessary measures shall be taken for construction in rainy season to avoid flooding and floating pipe. Once water enters the insulation materials, it will be difficult to eliminate them all, which will greatly reduce the insulation effect, increase the heat loss, and may cause damage and cracking of the insulation pipe; 3. In order to ensure the construction quality, argon arc welding shall be used as the backing for the welded junction, and 100% flaw detection shall be stopped for the trunk line; 4. Before the pipeline commissioning, the backfilling of the pipe trench must be stopped, and the rotary compensator shall ensure that the insulation layer shell forms sufficient friction with the soil to prevent the insulation layer from being damaged due to the stop of expansion and contraction of the insulation layer along with the inner steel pipe; 5. Strict initial operation procedures. During operation, the heating time must be ensured. Due to the high steam temperature, the temperature of the pipeline must rise slowly to ensure the smooth separation of the pipeline from the insulation layer and prevent the damage of the insulation layer. As the insulation layer is wet, the water in the insulation layer can be discharged evenly through the exhaust pipe only after being heated slowly, so as to avoid the pipe explosion of the insulation layer. When there is no gas discharged from the exhaust pipe at all, the steam supply can be increased and gradually reach the operating load value.