August 3, 2022
High and low temperature test chamber: suitable for reliability test of high temperature and low temperature of industrial products. To test the various performance indicators of the parts and materials of related products such as electronic and electrician, automobile and motorcycle, aerospace, ship weapons, colleges and universities, scientific research units, etc. under the condition of high temperature and low temperature (alternating) cycle.
The product has a wide temperature control range, and its performance indicators all meet the technical conditions of the national standard GB10592-89 high and low temperature test chamber. B: High temperature test method "The product is subjected to low temperature, high temperature test and constant temperature test. Products comply with GB2423.1, GB2423.2, GJB150.3, GJB150.4, IEC, MIL standards.
Basic information of high and low temperature test chamber:
The product of high and low temperature test box has the law of temperature change in simulated atmospheric environment. It is mainly aimed at the adaptability test of electrical, electronic products, and their components and other materials when transported and used in a comprehensive environment of high temperature and low temperature. For product design, improvement, identification and inspection and other links.
temperature fluctuation
This indicator is also called temperature stability. After controlling the temperature of the high and low temperature test box to stabilize, within a given time interval, the difference between the highest and lowest temperature at any point in the working space. There is a small difference here "workspace" is not "studio", it is a space about 1/10 of the length of each side of the box wall removed from the studio. This indicator evaluates the control technology of the product.
temperature range
Refers to the extreme temperature that the product high and low temperature test chamber can withstand and (or) reach. Usually contains the concept of constant control, which should be an extreme value that can operate stably for a relatively long time. Typical temperature ranges include extreme high and extreme low temperatures.
The general standard requires the index to be ≤1℃ or ±0.5℃.
temperature uniformity
The old standard is called uniformity, and the new standard is called gradient. After the temperature has stabilized, the maximum value of the difference between the average temperature values of any two points in the workspace at any time interval. Compared with the following temperature deviation index, this index can evaluate the core technology of the product. Therefore, many companies' samples and plans deliberately hide this. Guangdong Liyi Technology Co., Ltd. firmly safeguards the interests of customers.
The general standard requires the index to be ≤2℃
temperature deviation
After the temperature is stable, in any time interval, the difference between the average temperature of the center of the working space of the high and low temperature test chamber of Guangdong Liyi Technology Co., Ltd. and the average temperature of other points in the working space. Although the definition and name of this indicator are the same in the old and new standards, the test has changed. The new standard is more practical and harsh, but the assessment time is shorter.
The general standard requires the index to be ±2°C, and the pure high temperature test chamber above 200°C can be used according to the actual use temperature in degrees Celsius (°C) ±2%.
selection principle
The selection of environmental and reliability test equipment should follow the following five basic principles:
1. Reproducibility of environmental conditions
It is impossible to completely and accurately reproduce the environmental conditions existing in nature in Liyi's high and low temperature test chamber. However, within a certain tolerance range, people can accurately and approximately simulate the external environmental conditions experienced by engineering products during use, storage, and transportation. The created environmental conditions (including the platform environment) surrounding the tested product should meet the requirements of the environmental conditions and their tolerances specified in the product test specification.” For example, the temperature box used for the test of military products should not only meet the high temperature and low temperature test values and test time specified in the national military standards GJB150.3-86 and GJB150.4-86 according to different types of products, but also meet the test values. Requirements for the uniformity of the temperature field and the accuracy of temperature control in the specification. Only in this way can the reproducibility of the environmental conditions in the environmental test be guaranteed.
2. Repeatability of environmental conditions
A high and low temperature test chamber environmental test equipment may be used for multiple tests of the same type of product, and a tested engineering product may also be tested in different environmental test equipment. The comparability of the test results obtained under the specified environmental test conditions necessarily requires the environmental conditions provided by the environmental test equipment to be repeatable. That is to say, the stress level (such as thermal stress, vibration stress, electrical stress, etc.) applied by the environmental test equipment to the tested product is consistent with the requirements of the same test specification.
The repeatability of the environmental conditions provided by the environmental test equipment is guaranteed by the national metrological verification department after passing the verification according to the verification regulations formulated by the national technical supervision agency. To this end, the environmental test equipment must be required to meet the requirements of various technical indicators and accuracy indicators in the verification regulations, and the use time does not exceed the time limit specified in the verification cycle. If a very common electric vibrating table is used, in addition to meeting the technical indicators such as excitation force, frequency range, and load capacity, it must also meet the requirements of accuracy indicators such as lateral vibration ratio, table acceleration uniformity, and harmonic distortion specified in the verification regulations. , and the use cycle after each verification is two years, and it must be re-certified after two years before it can be put into use.
3. The controllability of environmental condition parameters
The environmental conditions provided by any high and low temperature test chamber environmental test equipment must be observable and controllable. This is not only to limit the environmental parameters within a certain tolerance range, but also to ensure the reproducibility and repetition of the test conditions. In addition, it is also necessary to proceed from the safety of product testing, in order to prevent damage to the tested product due to uncontrolled environmental conditions, resulting in unnecessary losses. Various test specifications generally require that the accuracy of parameter testing should not be less than one-third of the allowable error of the test conditions.
4. Exclusivity of environmental test conditions
Each environmental or reliability test carried out has strict regulations on the types, magnitudes and tolerances of environmental factors, and excludes environmental factors not required for the test to penetrate into it, so as to judge and analyze the product during or after the test. In the case of failure and failure mode, the exact basis is provided. Therefore, the environmental test equipment is required to provide the specified environmental conditions, and it is not allowed to add other environmental stress interference to the tested product. For example, the table surface leakage, acceleration signal-to-noise ratio, and the total root mean square value ratio of the acceleration in and out of the band as defined in the verification regulations of the electric vibrating table. Accuracy indicators such as random signal inspection and harmonic distortion are all verification items formulated to ensure the uniqueness of environmental test conditions.
5. Safety and reliability of test equipment
Environmental tests, especially reliability tests, have a long test period, and the test objects are sometimes high-value military products. During the test, the test personnel often need to operate or test around the site, so the environmental test equipment must have the ability to operate. Safety, convenient operation, reliable use, long working life, etc., to ensure the normal operation of the test itself. Various protection, alarm measures and safety interlocking devices of the test equipment should be perfect and reliable to ensure the safety and reliability of the test personnel, the tested product and the test equipment itself.
