Sheet metal and other machining materials are widely used. They not only have a variety of application forms in the machinery industry, but also have a wide range of application space in automobile manufacturing, aerospace and other fields, and are rapidly expanding and popularizing in other industries and fields. . The function of a sheet metal material is determined by factors such as how it is machined, its appearance, and its own material. It can reflect the mechanical maturity of the production process and the advanced nature of the manufacturing process.
With the rapid development of my country’s machinery manufacturing industry and the increasingly complex processing and manufacturing needs of sheet metal parts, a series of processing and processing processes such as the expansion calculation, bending, welding, and spraying of corresponding metal materials are directly related to the final sheet metal parts. The level of output quality, appearance and stability. In order to maintain a good appearance, sufficient strength and necessary precision, the calculation of the size of the sheet metal parts during the processing becomes a crucial link.
1 Bending process
Sheet metal bending is one of the most important processes in the processing process. The effect of bending will directly affect the size and appearance characteristics of the final product, which in turn will affect the selection of subsequent assembly welding processes and the difficulty of operation.From the point of view of technologyThe key processes in sheet metal unfolding calculation, bending, welding, spraying and other links are explained and interpreted. Analyze the existing problems one by one and give corresponding solutions. 1 Calculation of sheet metal unfolding length Bending work is bound to be involved in the manufacturing process of sheet metal parts. Before the bending process starts, the processing dimensions and notch positions of various parts should be clearly marked on the corresponding drawings to avoid the qualification rate of products due to errors in hole positions and external dimensions during subsequent laser cutting and other operations. decline. Reasonable processing methods can make product tolerances within the range of good products. At the same time, it is also convenient for the design of streamlined processing methods and the formulation of processing plans. Different raw materials of sheet metal parts will be elongated due to the action of bending moment, especially in the process of tension and compression, because the length of the neutral layer will not change significantly, and the overall development length of the inner and outer layers will be relatively large.
Therefore, calculating the length of the neutral layer has a high reference value.The actual unfolded length of a sheet metal part is often the sum of its straight line length and the length of the neutral layer.and. For the calculation of the length of the neutral layer, it is necessary to fully consider the type and thickness of its own materials, as well as external factors such as the mold used for processing. Since the processing of sheet metal parts is completed according to the corresponding mold, the bending radius is also equivalent to the size of the mold. Therefore, under the premise of no special requirements, the bending radius can be calculated by adopting the size equivalent to the mold, and the actual bending radius should not be paid too much attention.
In the actual production process of sheet metal parts, the corresponding bending compensation value is often difficult to predict in advance. For this reason, a test bend must be used to obtain the bend compensation value for a specific material. In this operation, a machine tool is first used to cut two equal-sized squares from a specific metal material as test samples. The standard size of the square material is obtained by measuring the dimensions in different directions, and then the length of the two right-angled sides after bending is measured by combining the bending operations in the parallel and vertical directions. The bending compensation generated at this time is approximately equal to the length of the two right-angled sides minus the side length of the original square material, thus indirectly obtaining the compensation value of the specific metal material in different directions. Combining with the corresponding calculation formula can further improve the accuracy of the calculation of the sheet unfolding length.
2.1 Minimum bending radius of sheet metal material
When bending sheet metal materials, the compressive strength of the inner layer and the tensile strength of the outer layer should be fully considered. Under the premise that the thickness of the original sheet metal material remains unchanged, the different bending strength and deformation angle of the material itself will change the compression and tensile strength of the material. When the tensile force reaches the tensile limit, the sheet metal material will inevitably crack or break. For this reason, in the process of bending parts and other operations, it is necessary to accurately grasp the minimum bending radius of sheet metal materials in advance. Avoid operation errors and cause unnecessary production and processing losses beyond the bending tolerance of sheet metal materials. Generally speaking, sheet metal parts are made of materials with large bending radii. If there is no special requirement for the radius in actual operation, the operation standard shall be that the bending fillet is smaller than the thickness of the sheet metal material.
2.2 Hole edge distance of sheet metal bending parts
When bending sheet metal, a certain distance must be maintained between the pre-reserved holes and the bending area. In order to avoid the huge deformation caused by the stretching of the hole position during bending, the sheet metal parts cannot be used normally. For this reason, in the design and processing of sheet metal materials, it is necessary to ensure that the distance between the hole edge and the outermost side edge after bending is greater than or equal to three times the thickness of the plate. If this method of controlling the distance is difficult to achieve, it is also possible to make small holes before the bending operation, and then expand the small holes after the bending deformation to indirectly achieve the same operation purpose.
2.3 Straight edge height of sheet metal bending parts
After the sheet metal part is bent at the specified angle, the determination of the height of the straight side needs to refer to the size of the bending angle for further judgment. For sheet metal components that are nearly vertical after bending and the angle reaches 90°, generally the height of the straight edge is twice the thickness of the material as the most suitable level. This is because from the design point of view, when the height of the straight edge is less than twice the thickness, it needs to go through a bending operation before subsequent processing. Only in this way can the established product size requirements be met. On the other hand, for some sheet metal parts with beveled edges, operations such as bending are often performed directly without considering the right-angled edges during the processing. After the bending is carried out, it is cut to make the sheet metal part change from a straight edge to a beveled edge to meet the processing requirements.
3 Sheet metal welding process
The welding of sheet metal parts often uses oxygen arc welding, resistance spot welding, carbon dioxide gas shielded welding and manual arc welding. The selection of the specific welding process and the formulation of the plan need to be considered in combination with the material, shape and use of the sheet metal parts. When choosing a welding process, technical requirements should be given top priority, and processing and manufacturing costs should be properly considered.In the actual processing of sheet metal parts, carbon dioxide gas shielded welding and argon arc welding are two types of welding.most commonly used. Because the welding effect of sheet metal materials is limited to a certain extent by welding equipment. To this end, the sheet metal parts should be thin plates with a thickness of less than two millimeters. The splicing process before welding should be prepared in advance for the subsequent welding work. In the key parts of the welding machine tool, the plate needs to be completely aligned. After ensuring that the surface is flat and no gaps, continuous spot welding is adopted. After welding, apply sheet metal glue to the seams for waterproofing. When encountering thicker materials and technical requirements such as full welding, it is necessary to adjust the corresponding current and voltage, and adjust the welding sequence of the corresponding operation in the way of segmented full welding. There may also be certain processing and process differences in the welding of sheet metal parts for different purposes. For example, for fuel tanks and other sheet metal parts that require high tightness. In order to avoid welding defects, it is necessary to fully weld with grooves at the flat welding position. After the welding is completed, it is polished and smoothed and the oil leakage detection is carried out in time.
4 Sheet metal spraying process
After the overall shape processing of the sheet metal part is determined and completed, further processing of the appearance is required. Spraying and other methods are the last process of sheet metal processing. The common sheet metal spraying process is plastic spraying. After the welded sheet metal is rusted in the pickling tank, the surface rust is polished off with a wire brush. Then use a polishing machine to treat the parts with uneven defects on the surface and other positions with obvious seams. After the surface putty is cured, subsequent processes such as powder spraying can be carried out. After the above operations are completed, the sprayed sheet metal parts need to be placed in a high temperature furnace of about 200°C for heating, and then taken out and placed in a room temperature environment to cool naturally.
The processing and manufacturing of sheet metal requires processing operations that not only meet the processing requirements, but also the characteristics of the composite material itself according to a specific bending coefficient compensation table. The refined operation process and precise operation precision can improve the overall level of sheet metal processing technology and the quality of products. After the welding deformation is effectively controlled and the surface treatment after welding is properly completed, the overall quality and aesthetics of the sheet metal products can be further improved. Create a steady stream of power for the development of sheet metal components processing and welding and the development of corresponding technologies.
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