Quality control of welding of the hottest automobi

2022-08-08
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Quality control of automobile structural parts welding

domestic and foreign automobile production enterprises carry out strict standard management for the welding of these automobile structural parts. This paper will introduce how advanced automobile manufacturing enterprises carry out quality planning, quality control and quality analysis of automobile structural parts welding, so as to help enterprises improve product quality

automobile structural parts are important parts of automobile load. Typical automobile structural parts include front suspension assembly of automobile chassis, rear axle assembly, subframe assembly and steel ring assembly of automobile. These components work in a harsh environment, which will not only be eroded by wastewater and exhaust gas, but also bear huge static load and impact load. Once these car structural parts are damaged, the high-speed car will suffer catastrophic events. Domestic and foreign automobile manufacturing enterprises carry out strict standard management for the welding of these automobile structural parts

quality planning before welding of automobile structural parts

quality planning of welding of automobile structural parts should be carried out according to the characteristics of product process. The main planning contents include the selection of facilities and equipment, the evaluation of process methods and the determination of testing items

selection of facilities and equipment

system requirements for welding facilities. (at present, most of the automobile structural parts are still processed by gas shielded welding, so this paper discusses the full-automatic welding machine as the main welding equipment.) in order to ensure the stability of the welding arc voltage of the welding machine, the workshop should be equipped with a reliable regulated power supply to control; Generally, the change of arc voltage in workshop circuit should be limited within 0.5V in order to make the welding machine operate normally. A large amount of exhaust gas will be produced during the welding of automobile structural parts. In order to protect the health of employees, exhaust devices must be provided. Since the welding methods of circulating water cooling and gas protection are generally used for automobile structural parts, the control requirements for the quality of circulating water, the mixing ratio of gas source and gas flow are put forward. In order to improve production efficiency, the workshop equipment should be arranged in a "U" shape and operated by one person with multiple machines, and a smooth production mode should be formed through the conveyor

capability requirements of welding equipment. Firstly, the mechanical performance, physical performance and electrical performance of the welding machine should have good stability, and the whole mechanical system should adapt to the physiological and psychological requirements of human operation; Secondly, in order to make the welding machine meet its special welding process, the factory invested in Zhangjiagang must start work. The welding torch should ensure that the welding process trajectory is stable and can make stepless adjustment in four-dimensional space; Finally, in order to make the welding equipment meet the production target of large batch and high efficiency, the welding machine should also have the adjustment requirements of welding ability to adapt to multiple products and multiple production rhythms

requirements for main technical parameters of welding equipment. The main technical parameters of welding equipment should be considered from the stability of input power supply, rated welding current, working voltage regulation range, rated load duration, wire feeding speed, welding speed and empty stroke speed, so as to realize the overall balance of the welding production line of automobile structural parts

evaluation of process methods

evaluation of welding process methods can ensure the stability of product quality in mass production. The purpose is to determine various welding equipment parameters and welding process parameters according to the requirements of the user's product structure, product raw materials and product welding accessories, and the welding requirements of different products

evaluation content of welding process method. The best welding method, welding sequence and replacement frequency of welding vulnerable parts (electrodes and nozzles) are selected through the determined welding environment requirements, product raw materials, welding auxiliary materials (welding wires, welding rods, welding fluxes, shielding gases) and the shape and angle of cut-out before welding of plates, as well as quality inspection methods, To select the most reasonable range of welding equipment parameters (input power supply, rated welding current, working voltage, rated load duration) and welding process parameters (welding current, arc voltage, wire feeding speed, welding speed, idle stroke speed, gas mixing ratio and gas source pressure)

procedure for welding procedure qualification. First, the welding engineer should put forward the "product welding process method qualification assignment", which lists the specific range of welding equipment parameters and welding process parameters; Under the supervision of the welding engineer, the relevant trial production department shall implement it according to the requirements of the assignment; Low gas release, which can be provided in the use of narrow frame. Due to the deformation and elongation of the sample in the tensile test, it is not only waterproof within the marking line - to ensure that when high-performance waterproof is required, the quality inspection department of the enterprise can detect the physical quality of the product according to the inspection items and methods of the task statement; The welder's technical grade, welding environment requirements, welding raw materials, welding auxiliary materials, welding process methods, welding equipment parameters and welding process parameters are evaluated by the welding engineer; Finally, the welding engineer in charge prepares the welding process method evaluation report according to the inspection of the physical quality of the product and the evaluation of the welding engineer. The report is signed by the relevant departments participating in the evaluation, and approved and issued by the leader in charge of enterprise technology; The technical department will prepare equipment operation specifications, welding process specifications and welding inspection specifications according to the contents determined in the approved product welding process method qualification report. It must be noted that if the main content of product process evaluation is to be changed, the enterprise should organize relevant departments to evaluate again, otherwise the stability of product quality will be affected

determination of test items

it is necessary to correctly determine the establishment of test items, the judgment criteria of test items and the allocation of test means in the welding process of automobile structural parts

establishment of testing items. There are two aspects for the project establishment of automobile welded structural parts inspection project: first, the standards and regulations requirements of domestic and foreign automobile enterprises for the welding of various automobile structural parts; The second is the requirements of product drawings and technical documents provided by specific users

criteria for determining test items. The judgment criteria of welding inspection items are based on ensuring the safety and reliability of products. First of all, when formulating the judgment criteria of testing items, we must aim at the special requirements of users, safety requirements, reliability requirements and government regulations; Secondly, the inspection specification must be prepared according to the standardization requirements. This inspection specification must indicate the quality characteristics, inspection methods, inspection means and inspection frequency; Finally, the inspection record requirements of the test items must be specified

allocation of inspection means. According to the product characteristics and process characteristics of automobile welded structural parts, it is the key to determine the appropriate detection means. The so-called reasonable selection of detection means is to correctly analyze the measurement error, so that the accuracy of detection means can meet the requirements of product quality characteristics; Correctly analyze the measurement speed, so that the detection time and frequency of the measurement means can meet the requirements of the production beat and the output of each shift. Therefore, in the actual production process of automobile welded structural parts, size detection instruments and standard samples should be equipped to measure the size of products; For routine physical, chemical and mechanical performance testing items, conventional testing means can be equipped according to the requirements of the inspection specifications; For the detection items with special requirements of users, various special detection means should be equipped according to the requirements of users

quality control of automobile structural parts welding

the quality control of automobile welded structural parts should also start from the three links of raw material control, process factor control and physical quality control according to the particularity of products and processes

control of raw materials

raw material control of automobile welded structural parts should be considered from the aspects of material ordering, material incoming acceptance, material inventory storage, material receiving and sending, and material preparation control of welded parts. Among them, the material preparation of weldments generally includes three processes: plate blanking, plate edge treatment and plate pre welding preparation. For the blanking of plates, the batch number, heat number, brand and specification requirements of materials should be controlled to ensure that these blanking plates are not confused; For the edge treatment of sheet metal, the shape, angle and size of the cut should be controlled to ensure that these sheets can be welded normally; For the preparation of sheet metal before welding, the cleaning quality and burr height of sheet metal should be controlled to ensure the stability of welding quality

control of raw materials

control the process factors of automotive welded structural parts, that is, focus on the skill quality of personnel, the stability of facility and equipment parameters, and the compliance of process parameters. (1) Control of personnel skills and quality. The control of welder's skill and quality is to control the welder's ability to realize the stability of product quality according to the specified production process within the specified production time. Only when the welder has the skill and quality can he implement the process factor control. (2) Stability control of facility and equipment parameters. According to the product quality characteristics requirements of various automobile welded structural parts, the enterprise shall design a quantitative equipment spot check list reflecting the characteristics requirements of welding machine equipment. This spot check list shall require the welding workers to record the characteristic parameters of various equipment within the specified time, and require the workshop management personnel to spot check the records from time to time. (3) Compliance control of process parameters. The enterprise shall indicate various process parameters for the processing of various automobile welded structural parts, and the quantitative process parameter record form or computer link can be used to record these process parameters

control of physical quality

for special products such as automobile welded structural parts, strengthening the first piece quality inspection of products, the quality control of non main devices, non main control systems and returned workpieces of non key stations used in large-scale engineering projects, and product type test are the basis for realizing the effective control of physical quality of products

first article quality inspection. Because the processing of this kind of products is generally continuous production under the equipment with a high degree of automation. Therefore, the first piece quality inspection of this kind of products is very important. First, the welder must check whether the process track of the welding equipment and the process parameters of product processing meet the specified requirements; Secondly, when the first product is processed, the welder must check whether the materials provided by the product logistics card meet the specified requirements according to the requirements of the inspection specifications; Use the measuring sample rack to check whether the geometric dimension of the product meets the requirements; Finally, check whether the weld has defects such as pores, splashes, misalignments, undercuts, etc. according to the defect standard sample, and fill the self inspection results into the three inspection inspection card. Then, the inspector shall recheck the self inspection items of the welder, and then check whether the welding penetration, metallographic structure, mechanical strength and the special requirements of the user meet the specified requirements. When these inspection items meet the requirements and the inspection results are filled in the three inspection card, the operators can carry out mass production

quality control of returned workpieces. First, review the defective products, classify the defects and find out the causes of the defective products; Secondly, it should indicate the rework process of defective products and formulate corrective measures; Finally, these reworked products should also be re inspected according to the requirements of the inspection specifications. It must be noted that the same part of these defective products can only be reworked once, otherwise it will cause adverse effects on the weld and heat affected zone, easy to produce hardening, cracks, coarse grains, and seriously affect the welding quality

strengthen product type test. For safety products such as automotive weldments and structural parts, the product type test must be strengthened, especially for defective products fed back by users, the fatigue test should be carried out by imitating the working conditions of harsh environment

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