3.1.3 Quality inspection of foundry raw materials
The supply of imported raw materials in foreign countries is timely supplied and delivered by specialized materials companies with uniform and strict standards, so the foundry can obtain quality assurance. However, due to the fact that there are many sources of raw materials, low standards, mixed varieties, large fluctuations in quality, unregulated supply channels, and the current situation of urgent and less re-inspection and lack of means for factories, the domestic automobile foundry has not known the quality and efficiency for many years. How much suffering has been eaten. Therefore, it is very important and particularly important to supplement and expand the high-speed, comprehensive and versatile modern testing methods for raw materials. For example, in recent years, the introduction of the latest raw material testing method, "X-Fluorescence Spectrometer", which can be used as a spheroidizing agent and inoculant in 5 minutes, can complete various iron alloys, desulfurizers, slags, refractories, Full analysis of raw materials such as minerals; chemical analysis is used for at least one day; and portable “alloy analyzers†can be used to complete the mixing of various black and non-ferrous alloy materials in the pits and workshops within 5 minutes. Detection problems of material parts and so on.
3.1.4 Metallographic structure and mechanical properties testing
At present, most of the domestic automobile foundries still use the optical metallographic microscope and universal material testing machine in the 1960s and 1970s, and can only maintain the general metallographic structure and mechanical properties of the project according to the national standard. Not only the equipment is aging and backward, but also has low precision, low function and large human error. Therefore, not only is the gap far from the foreign level far, but it can not meet the requirements of casting upgrade, failure analysis, new product development and overseas casting inspection, and it is impossible to complete the new indicator detection proposed by the new concept of modern casting quality assessment. For example, the "spheroidization rate" of the ball iron castings in foreign countries is evaluated by the "image analyzer" matched with the optical microscope as the quantitative metallographic phase; and the mechanical properties of the cast iron are also measured by the modern "electronic tensile testing machine". "To make the mechanical performance test go to "automation" and "intelligence", and also to create convenient conditions for the comprehensive comprehensive mechanical properties of cast iron materials (with automatic X-Y function recorder).
3.1.5 core sand performance testing
The level of core sand instruments manufactured in China has been much behind that of foreign countries. Not only is the design and processing rough, the quality is poor, the varieties are not complete, and the correction means of self-checking gauges are lacking. At present, many core sand instruments used in automobile foundries are still old and aging, and they do not pay attention to renewal and replacement. Therefore, the guiding significance for current production is even smaller, and may even be misleading. This is a problem that must be valued and corrected. Taking into account the development direction of core sand instruments in the future, one is from laboratory testing to production site control development, and the other is from single test to comprehensive testing, intelligent and mechatronics development, so it should pay attention to update, replacement and supplement. New instruments and appropriate introduction of the necessary foreign core sand instruments. For example, the PVT type pneumatic-electronic sand performance tester produced by Swiss GF company; and the "408 test center" controlled by electronic computer in De1eret Company of the United Kingdom.
3.1.6 Casting line inspection
The level of casting marking test of automobile foundry in China has been at a rather backward level compared with foreign countries. Many factories still use old-fashioned measuring tools such as height gauges and calipers in the 1960s to cast the castings, which is not only laborious, but also has poor precision, low work efficiency and slow speed. In order to improve the size of the scribing accuracy and double the efficiency of casting scribing, in order to adapt to the quality upgrade requirements of modern high-grade castings in the future, on the one hand, we must pay attention to continuously update and supplement modern new types of measuring tools such as digital electronic measuring tools; On the one hand, it should be considered to measure the scriber with a three-dimensional coordinate casting with an accuracy of 0.05 or 0.10 mm.
3.1.7 Non-destructive testing of castings
The non-destructive testing of castings has always been the weakest link in the testing technology and means of automobile casting enterprises in China. Compared with foreign countries, it is a late start and a big gap. At present, it is generally not suitable for the development of high-quality, high-reliability and high-security technical requirements for castings for overseas markets, modern automobile castings, and especially for high-class car castings. In particular, some key castings require 100% non-destructive magnetic particle inspection, radiographic inspection, ultrasonic testing or spheroidization testing, hardness and substrate testing, wall thickness testing, water (gas) pressure testing, etc. For a modern automotive casting In the factory, these testing methods should be gradually established and expanded; some must have at least the means and capability of spot testing; for castings that are particularly critical and require 100% non-destructive testing, "online automatic detection" and "online automatic sorting" should be performed. Complete equipment means. (For example, the Chrysler foundry of the French Citroen Automobile Company has these online testing methods.) The author must point out that the cast iron blanks have poor surface finish, loose material, coarse grain and internal The presence of graphite and other factors, it is necessary to pay attention to the choice of testing methods, instrument selection, equipment support, operating technology and personnel experience.
3.1.8 Casting surface quality inspection
Inspection of surface defects of castings is generally by visual inspection, including the use of a magnifying glass method of less than ten times, the use of modern industrial endoscope methods, and the like. In order to improve the resolution, methods such as fluorescent flaw detection, color flaw detection, and magnetic particle inspection can also be used to find defects on or near the surface. In the inspection of large-flow water-based automobile casting production line, special large-scale, complex and special important castings should also be developed with special on-line automatic quantity fixtures for main size inspection and development of special casting (blank) hydraulic press for automatic leakage inspection, etc. .
3.1.9 Casting performance testing and process research
Casting performance testing and research is an important basic condition for formulating the correct casting process and obtaining high-yield, high-quality, low-defect rate castings; it is also an effective means to guide the improvement of casting process, the trial production of new products and the development of modern high-tech castings. This aspect started late in China, and the development of instruments is also lagging behind abroad. Until now, China's automobile foundry has not paid attention to it and has not established and perfected these testing techniques. These properties include fluidity, line shrinkage, body shrinkage, thermal cracking, casting stress, casting expansion force, alloy freezing point, gettering, gas content, and activity with the mold. In this regard, the automobile foundry industry should gradually carry out testing and research, which is necessary. In addition, the simulation test of the casting solidification process, the CAD casting tooling design with the microcomputer and the evaluation of the quality index of modern castings should be taken seriously.
3.1.10 furnace gas analysis and testing
Furnace gas analysis is a very important job. The analysis of CO and CO 2 content in the furnace gas of the cupola can grasp the combustion conditions and metallurgical reaction conditions, and thus can correctly judge the furnace condition, control the melting operation, and improve the melting process; and calculate the heating efficiency of the coke and the furnace accordingly. The thermal efficiency thus guides the improvement of the iron-to-focus ratio and the cost reduction. This is also an important task for China's automobile foundry industry to move toward high production, high quality, low consumption and increase economic benefits in the future. This kind of testing method has already been available in China. Such as gas chromatograph, infrared gas analyzer, etc. In particular, the gas chromatograph can be used not only for furnace gas analysis, but also for analyzing the N, O, and H contents in cast iron.
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