The thermal shock Test Chamber is customized according to user needs and is divided into two or three parts: high temperature zone and low temperature zone. Place the test sample in a movable basket. A unique heat storage and cold storage structure is adopted. At the same time, the cylinder drives the hanging basket to perform cold and hot movements, and moves up and down in the tank to complete the cold and heat shock test. Applicable objects include metal, plastic, rubber, electronic products, etc., which can be used as the basis or reference for product improvement. Frost is the result of rapid cooling and crystallization of water in the air when it is cold. Frost is small ice crystals that easily turn to ice when thick. The frosting in the thermal shock Test Chamber is mainly concentrated on the energy storage elements in the precooling zone.
Frost source and defrosting principle
We know that the cold and hot cycle shock Test Chamber performs heat exchange through the airflow conversion in the three boxes to achieve the shock effect. These three boxes are isolated from the air outside the box, that is to say, relative to the outside world, these three boxes are airtight. Since it is a closed space, their water content is quantitative, and resistance cannot be generated from thin air. When the extra moisture arrives, that is, theoretically, the pre-cooling zone should be free of frost. But tracing back to the source, where does the moisture come from? Of the three boxes, there is only a testing area for customers to open and place products. If moisture is to be introduced, it should only be introduced after the test area has been opened. Therefore, one source of moisture is the customer's door opening operation. However, we are not allowed to open the door in the middle of completing the impact test, otherwise the test will fail. Another source of moisture needs to start in the test area.
Some Test Chamber manufacturers can do 1000 cycles with one defrost, which means their equipment avoids introducing moisture as much as possible. Why do some manufacturers need to defrost once when doing 20 cycles? Do good end devices need to be non-hermetic? Or is there a deeper reason? The answer is yes. When some manufacturers in the industry design cold shock and heat shock to minimize manufacturing cost and save compressor horsepower, they use a secret method of releasing heat energy, which is to open the valve outside the test area to reduce the pressure in the test area. contained heat. In this way, whether it is high temperature shock or low temperature shock, it has the ability of low temperature or high temperature, and the high-low Temperature Test Chamber will be discharged to the outside. Therefore, the purpose of reducing the cost of the energy storage element is achieved. In this way, a large amount of water will inevitably be introduced, and frost will inevitably occur in the pre-cooling area. This technique is called "storage launch". It is also one of the key practices of the industry.
Defrost Frequency Method
There are two methods. One is to set the time and the other is to set the cycle time. Generally, most manufacturers and customers seldom use the set time to defrost, because its disadvantage is that the equipment may still be running after the set defrost time is over. During the test, the cycle time is for defrosting after the thermal shock test is completed, so the cycle time is recommended.
All cold cycle and thermal cycle shock chambers are factory-set with a defrost frequency such as every 20 cycles or every 20 hours. After the number of cycles has been reached, defrost will be performed automatically. Users do not need to modify according to the recommended value. If customers have their own defrosting frequency requirements, they can modify the number of cycles or time in the defrosting settings of the equipment control system. Regarding the range of settable values: it can be set within 1 to 9999 hours according to the time, and within 1 to 9999 times according to the cycle time.
