With the rapid development of modern welding technology, the continuous improvement of welding production level and the increasing expansion of international welding product trade, in order to ensure the quality of welding products, effectively utilize resources and protect the interests of users, the quality management of welding products has gradually embarked on Standardized and standardized road.
In March 1987, the International Organization for Standardization (ISO) officially released the ISO9000-9004 standard series on quality management and quality assurance.
In 1994 and 2000, the International Organization for Standardization revised the ISO9000 family of standards twice, making them more simplified, more focused, more scientific and universal, and raised the quality assurance system to the level of quality management systems.
In 2000, my country issued the GB/T19000:2000 "Quality Management System" standard series equivalent to adopting the international standard series.
Modern quality management believes that in order to make the product meet the required quality indicators, it should start from each process of production, and ensure it by controlling and adjusting the factors that affect the quality of the process. The quality of the process must be achieved through the quality of work and various management methods.
Therefore, in the quality management work, the quality of the work should be used to ensure the quality of the process, and the quality of the process should be used to ensure the quality of the product.
It can be seen that in order to achieve quality goals, it is necessary to establish an effective and easy-to-operate quality management system in the management system. And this system is applied to the entire manufacturing process of the product.
Knowledge point 1: Influencing factors and countermeasures of welding process quality
1. People----Welding operator factors
2. Machine-----Welding machinery and equipment factors
3. Material-----welding raw material factors
4. Method-----welding process method factors
5. Ring----Environmental Factors
Process quality refers to the degree of assurance of product quality by the processing process in the production process. In other words, product quality is based on process quality, and it is necessary to have excellent process quality to produce excellent products.
The quality of the product is not only achieved after the completion of all the processing and assembly work, through the determination of a number of technical parameters by full-time inspectors and the approval of the user, but the quality of the product exists at the beginning of the processing process and runs through the whole process of production.
Whether the final product is qualified or not depends on the cumulative result of all process errors. Therefore, the process is the basic link of the production process and the basic link of the inspection.
The production of welded structures includes many processes, such as decontamination and rust removal of metal materials, straightening, scribing, blanking, groove edge processing, forming, assembly, welding, and heat treatment of welded structures during material preparation. Each process has certain quality requirements, and there are factors that affect its quality.
Since the quality of the process will ultimately determine the quality of the product, it is necessary to analyze various factors that affect the quality of the process and take practical and effective control measures to ensure the quality of the welded products.
The factors that affect the quality of the process can be summed up as five aspects: personnel, equipment, materials, process methods and production environment, referred to as "human, machine, material, method, and environment" five factors. The influence of each factor on the quality of different processes is very different, and it should be analyzed on a case-by-case basis.
Welding is an important process in the production of welded structures, and the factors affecting its quality are also the above five aspects.
1. People----Welding operator factors
The various welding methods have varying degrees of operator dependence.
For manual arc welding, the welder's operating skills and careful work attitude are essential to ensure the welding quality.
For automatic submerged arc welding, the adjustment of welding process parameters and welding are also inseparable from human operation.
For all kinds of semi-automatic welding, the movement of the arc along the welding joint is also controlled by the welder. If the welder has poor quality awareness during welding, careless operation, non-compliance with the welding procedure regulations, or low operating skills and unskilled skills, the quality of direct welding will be affected.
The control measures for welding personnel are as follows:
(1) Strengthen the quality awareness education for welders of "quality first, users first, and the next process is the user", improve their sense of responsibility and meticulous work style, and establish a quality responsibility system.
(2) Regular on-the-job training for welders to master the technical specifications in theory and improve the level of operational skills in practice.
(3) Welders are required to strictly implement the welding procedure regulations during production, and strengthen the self-inspection of the welding process and the inspection of full-time inspectors.
(4) Conscientiously implement the welder examination system, insist that welders hold certificates and establish welder technical files.
For the production of important or significant welded structures, a more detailed consideration of the welder is required. For example, the length of the welder's training time, production experience, current technical status, age, length of service, physical strength, vision, attention, etc., should all be included in the scope of the assessment.
2. Machine-----Welding machinery and equipment factors
The performance, stability and reliability of various welding equipment directly affect the welding quality. The more complex the equipment structure, the higher the degree of mechanization and automation, the higher the dependence of welding quality on it.
Therefore, such equipment is required to have better performance and stability. Welding equipment must be inspected and tried before use, and a regular inspection system shall be implemented for various in-service welding equipment.
In the welding quality assurance system, starting from ensuring the quality of the welding process, the welding equipment should do the following:
(1) Regular maintenance, maintenance and overhaul of welding equipment, and trial of important welded structures before production.
(2) Regularly check the ammeters, voltmeters, gas flow meters and other instruments on the welding equipment to ensure accurate measurement during production.
(3) Establish technical files of welding equipment conditions to provide ideas for analyzing and solving problems.
(4) Establish a responsibility system for welding equipment users to ensure the timeliness and continuity of equipment maintenance.
In addition, the use conditions of the welding equipment, such as the requirements for water, electricity, environment, etc., the adjustability of the welding equipment, the space required for operation, and the adjustment of errors also need to be fully paid attention to, so as to ensure the normal use of the welding equipment.
3. Material-----welding raw material factors
The raw materials used in welding production include base metal, welding materials (electrode, welding wire, flux, shielding gas), etc. The quality of these materials is the basis and prerequisite for ensuring the quality of welding products.
In order to ensure the welding quality, the quality inspection of raw materials is very important. In the initial stage of production, that is, it is necessary to close the material before feeding, so as to stabilize the production and stabilize the quality of the welded products.
In the welding quality management system, the quality control of welding raw materials mainly includes the following measures:
(1) Strengthen the acceptance and inspection of welding raw materials, and re-examine their physical and chemical indicators and mechanical properties if necessary.
(2) Establish a strict management system for welding raw materials to prevent contamination of welding raw materials during storage.
(3) Implement the welding raw material marking operation system in production to realize the tracking control of the quality of welding raw materials.
(4) Choose welding raw material suppliers and cooperative factories with relatively high reputation and good product quality for ordering and processing, so as to fundamentally prevent the occurrence of welding quality accidents.
In short, the inspection of welding raw materials should be based on welding specifications and national standards, and their quality should be tracked and controlled in time, instead of just entering the factory for acceptance, ignoring the marking and inspection in the production process.
4. Method-----welding process method factors
Welding quality has a strong dependence on the process method, and occupies a very prominent position in the factors affecting the quality of the welding process.
The influence of the construction method on the welding quality mainly comes from two aspects, one is the rationality of the process formulation; the other is the strictness of the implementation process.
First of all, the welding process of a certain product or a certain material should be evaluated by the process, and then the welding process specification should be formulated according to the process evaluation report and the technical requirements of the drawing, and the welding process specification or welding process card should be prepared. These various process parameters expressed in written form It is the basis for guiding the welding process. It is compiled based on the experiments and long-term accumulated experience of simulating similar production conditions and the specific technical requirements of the product. It is an important basis for ensuring the welding quality. It has regulations and seriousness. , prudence and continuity. It is usually compiled by experienced welding technicians to ensure its correctness and rationality.
On this basis, it is ensured that the strictness of the process method is implemented, and the process parameters cannot be arbitrarily changed without sufficient basis. Even if it is really necessary to change, certain procedures and procedures must be performed.
The unreasonable welding process cannot guarantee the welding of qualified welds, but with the correct and reasonable process regulations verified by the assessment, if not strictly implemented, the qualified welds cannot be welded. The two complement each other and depend on each other, and neither can be ignored or neglected.
In the welding quality management system, the effective control of the factors affecting the welding process method is as follows:
(1) Welding procedures must be evaluated in accordance with relevant regulations or national standards.
(2) Select an experienced welding technician to compile the required process documents, and the process documents should be complete and continuous.
(3) Strengthen the on-site management and supervision during the welding process in accordance with the provisions of the welding procedure specification.
(4) Before production, the welding product test plate and the welding process inspection test plate should be made according to the welding process specification to verify the correctness and rationality of the process method.
In addition, the formulation of the welding procedure specification is detailed, and there must be a remedial plan for quality accidents for important welded structures to minimize losses.
5. Ring----Environmental Factors
In a specific environment, the welding quality is also highly dependent on the environment. Welding operations are often carried out in the open air, and are inevitably affected by external natural conditions (such as temperature, humidity, wind, rain and snow), and under certain other factors, it is also possible that welding quality problems may be caused simply by environmental factors.
Therefore, some attention should also be paid. In the welding quality management system, the control measures for environmental factors are relatively simple. When the environmental conditions do not meet the specified requirements, such as strong wind, wind speed greater than four, or rain and snow, the relative humidity is greater than 90%, the welding work can be temporarily stopped , or take measures to prevent wind, rain and snow before welding;
When welding at low temperature, the low carbon steel shall not be lower than -20°C, and the ordinary alloy steel shall not be lower than -10°C. If this temperature limit is exceeded, the workpiece can be properly preheated.
Through the above analysis of the five factors affecting the quality of the welding process and their control measures and principles, it can be seen that the five factors are interrelated and intersect each other, and they must be considered systematically and continuously.
