Production Process And Production Technology of Large Equipment Steel Structure

With the development of economy and society, the need for large-scale equipment in production is also constantly developing. At the same time, the development of social economy and the progress of science and technology have provided the possibility of manufacturing these large-scale equipment. However, the manufacturing process of large equipment is quite complex, in addition to electronic, hydraulic and other components of these equipment, its own structure is also quite complex, accounting for a considerable proportion of the entire equipment.

In this paper, based on the structure of the equipment itself, from the manufacturing process and production technology, to explain this complex production process in detail.

1. The first step in the production of equipment steel structure: disassemble the drawing and cut the material

The blanking process is to process steel plates or profiles into the required parts. The blanking process is mainly divided into three types: the blanking of steel plates, the blanking of profiles and the receiving of residual materials. As the first step of structure production, dismantling the drawing and cutting materials is actually to do technical support for production, and it is also a reliable basis for raw material procurement. Therefore, in this process, as a technical personnel must consider the drawings in all aspects, taking into account the production process, which is the most beneficial to the production. The process of cutting must pay attention to the following points:

(1) Correctly grasp the drawings, must be fully audited, so that the understanding and grasp of the drawings are correct;

(2) In the production of the material list must pay attention to the number and material of the plate, the drawing of the material diagram to be correct (mainly refers to the size of the material diagram, because the size of the material diagram to consider the process, such as the size of the material to consider the amount of welding shrinkage, machining, etc.); 

(3) The bonding of the remaining materials should comply with the corresponding specifications of the drawings, especially the welding aspect;

(4) For sheet cutting, when cutting with plasma or numerical control, it is necessary to correct the cutting machine before cutting to ensure the dimensional accuracy of the cut sheet;

(5) The pre-treatment of the welding groove, the groove must be cleaned up after processing to ensure the completion of this process, do not bring unnecessary trouble into the next process;

(6) The treatment of the hole, the hole is generally divided into pre-drilling and assembly welding drilling, so in this process must carefully check the drawings, distinguish the time point of the hole processing;

2. The assembly and welding of the steel structure of the equipment, that is, the riveting welding stage

The assembly process is to assemble the good materials into the required components or pre-assembly parts according to the requirements of the drawings. After the assembly is completed, welding shall be carried out according to the corresponding welding specifications of the drawings. This project is referred to as riveting welding.

Preliminary preparation stage:

(1) When assembling, check the sheet material, review the drawings, prepare welding equipment and welding materials, and equip personnel;

(2) According to the drawings before the assembly of the tire frame production, this process generally uses a lot of ground appearance, according to the drawings after the ground appearance to check the unity of the ground appearance and drawings, so as to ensure the correctness of the ground appearance;

Implementation stage:

(1) Assemble the parts according to the drawings, and some parts that need to be pre-assembled are also made in advance, so as to be available at any time during assembly. This process must be recorded in advance of the production process, assembly must be operated in accordance with the production process, in order to avoid the impact of errors in the assembly process on the subsequent process, but also an effective guarantee for the production plan.

(2) Welding should be performed after assembly, and welding should be carried out according to the welding process before welding;

(3) After the completion of the group welding, it is necessary to self-check again, and after determining that there is no problem, it should be applied for inspection, and comprehensive inspection of the appearance size and weld path. After passing the inspection, the next process can be carried out.

3. Correction of equipment steel structure after welding

Due to the rapid non-equilibrium heating and cooling in the welding process, the structure will inevitably produce welding residual deformation which cannot be ignored. Welding residual deformation is a key factor affecting the integrity of structural design, the rationality of manufacturing process and the reliability of structural use. Therefore, after the completion of welding, post-welding correction is required. The methods of correction are generally as follows:

(1) Manual correction

(2) mechanical correction method: the principle of mechanical correction of deformation, forced recovery of component size, generally used in the production of chain pulling, etc., generally used in small structural parts.

(3) Flame heating correction: Through local heating and subsequent rapid cooling, the elongation of the welding part is shortened to achieve the purpose of correcting the deformation. It is worth noting that water cooling is generally used in the actual production process, which seriously affects the characteristics of the material, and is generally not recommended. The way of flame heating is point heating, line heating and triangle heating. This method is in production

Direct welding torch, does not require special equipment, simple and convenient operation, can be used in large complex structures.

(4) The aging method will also be used for oversized welded components

Law: Generally divided into natural aging and artificial aging. Mainly for the stress concentration generated after welding, the internal stress can be reduced after the aging method

4. Coating of steel structure of equipment

Coating is an effective way to prevent corrosion. The oxide, rust, etc., produced by the steel surface itself, and the pollutants brought by the processing or transportation and storage of the components, such as grease, dust, chemicals, etc. These contaminants directly affect the adhesion, uniformity, densification and gloss of the coating.

5. Shipment of equipment steel structure

For the transportation of large steel structure is also one of the complex processes, because it involves multiple factors such as safety, construction period, cost, etc., so it is also necessary to make scientific and reasonable arrangements for the transportation process. 

(1) Preparation of shipping instructions:

It is used to organize and guide the transportation of components, ensure the transportation safety of components, scientifically and reasonably arrange transportation routes and means of transport, and fully consider cost problems and construction period.

(2) Packaging of components: packaged products must be qualified for product inspection, complete accompanying documents, and dry paint film; Packaging is based on the characteristics of the steel structure, transportation, loading and unloading conditions and other requirements of the operation, to achieve compact packaging, careful protection, safe and reliable; Product packaging should have sufficient strength to ensure that the product can withstand multiple loading and unloading, transportation without damage, deformation, reduced accuracy, rust, loss, safe and reliable delivery to the destination; There should be a barrier between packaging materials and components to avoid wear and miscibility; There shall be marks, center of gravity and lifting marks on all cases; In the packing list, the component number should be clearly marked; The color of packaging materials and components should be significantly different; When packing, the protruding parts should face the inside of the packing box as far as possible to avoid collision and deformation during transportation;

(3) Protection measures during transportation: lifting large, super long and heavy components must be responsible for the use of appropriate jigs, rigging, strict compliance with the lifting rules to prevent vibration, impact, deformation, fall or other damage during the lifting process; When loading, there must be special supervision, check the box number and packing number on the car, pile the car firmly and securely, and increase the necessary tying to prevent the loose and loss of components; In the transportation process to maintain stability, when the vehicle is loaded, the transportation of ultra-long, ultra-wide and ultra-high components must be transported by trained and experienced full-time drivers, and escort personnel are responsible for the coordination and command of special sections, and set marks on the vehicle; Rough loading and unloading is strictly prohibited. Before loading and unloading, the loading and unloading personnel should be familiar with the weight and dimensions of the components, and check the situation of the spreader and rigging to prevent accidents; After the components arrive at the construction site, they should be unloaded in time, stacked in partitions, and those that can be transferred to the installation position can be lifted to the corresponding position in the construction section as soon as possible to reduce the secondary handling

Through the above analysis of this paper, we need to realize that: large-scale equipment structure as one of the common forms of steel structure in the modern manufacturing industry, but also a rather complex one, there are many noteworthy places in the production process and production technology, by summarizing the hope to be used for reference and improvement in the future production process. All in all, this paper makes a brief analysis and explanation of the related problems involved in the manufacturing process and production process of the steel structure of the equipment, hoping to provide help for the production in the future.

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