Cold assembly technology of industrial refrigerator

Generally, when the temperature changes, the volume of the object will always change. Most objects (including solid, liquid, gas) will increase when the temperature rises, and the volume will decrease when the temperature decreases. This phenomenon is called thermal expansion and cold contraction. In industrial production, the phenomenon of thermal expansion and cold contraction is widely used. For example, in the process of mechanical assembly, there are many parts that need static matching This kind of static fit is characterized by that the hole size is smaller than that of the shaft (or shaft sleeve), and there is interference phenomenon when the two fit, so that they can be firmly combined However, this method is only suitable for small size workpieces, and has its obvious disadvantages: in the process of knocking or extrusion, it will affect the geometric accuracy of the workpiece. For large workpieces or workpieces with high geometric accuracy requirements, the “hot sleeve” method is commonly used to realize the static fit between workpieces In other words, the workpiece with a hole is heated in the oil tank to expand the hole, and then another matching workpiece is installed in the hole. After cooling, the two workpieces can be firmly combined. However, the “hot sleeve” also has disadvantages: first, the production efficiency is low, because the workpieces with holes are often large parts such as frame and box, so it takes a long time to heat in oil, and generally it takes as much as eight hours to heat Long time heating is an intolerable disadvantage for the assembly line. Secondly, the heating of oil tank consumes a lot of energy. Moreover, the oil wave overflows and the oil smoke diffuses after the oil is heated. When the workpiece is taken out of the oil tank, the oil drops, which will pollute the environment.

In order to overcome the shortcomings of “hot sleeve”, a new method is created in practice, that is, one of the two static matching workpieces is cooled in the industrial refrigerator to reduce its diameter, and then put it into the hole of another workpiece. After the temperature rises, the two workpieces will be firmly combined. This assembly technology is the same as the “hot sleeve” method The purpose of static fit between machine parts is presented. This kind of technology, which first cools the workpiece in the industrial refrigerator and then carries out assembly, is called cold assembly technology of industrial refrigerator.

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