I. Functional requirements
Functional requirements are mainly to meet the system's structural requirements, strength requirements, shielding requirements, grounding conductivity. The structure of the system is a system of hardware, PCB boards, wires, power supply and other space to place the location, form, connection and assembly methods. Sheet metal parts are usually used to support most of the hardware, PCB boards, wires, power supplies, etc. in the system due to their good strength, steelness, processability, and conductivity. Hardware can be placed in a variety of forms and their requirements can vary. Mechanical strength is one of the most important aspects of sheet metal part design. Since most of the weight in the system is supported by the sheet metal parts, if the mechanical strength of the sheet metal parts is a problem, the whole strength of the system will be a problem. Medical instruments generally need to do vibration test, drop test, collision test, impact test, etc. Some machines even require the strength to be able to withstand the impact of 100g, which requires sufficient mechanical strength and steel. Especially those who need to support the suspended hardware sheet metal parts, and play a major role in supporting the bracket, more must have better strength.
II. Process Requirements
The processing equipment for sheet metal parts mainly includes CNC punching machines, bending machines, punching machines, shearing machines, milling machines, drilling machines, welding equipment and so on (the attached table is the statistics of Mycen's machinery and equipment). Sheet metal forming can be summarized into three basic types: compression type forming, elongation type forming and bending type forming.
The processes of straightening, bending, rolling, punching and deep-drawing in the processing of sheet metal parts all utilize the plastic deformation of metal at room temperature to become the desired shape. Therefore, the plastic deformation of metal is the basis of metal forming.
Metal in the cold state by the external force, its shape and size will change, this change can be elastic, can also be plastic. When the external force is lifted, can restore its original shape and size is elastic deformation, and vice versa is plastic deformation. Metal plastic deformation zui basic form is slip.
1, punching: punching is the use of the die will be a closed profile and blank separation of a stamping method, the main equipment is the press. Can be made into finished parts, can also be used as bending, deep drawing, and molding and other processes to prepare blanks. Punching is divided into two kinds of drop and punch. The use of punching to obtain a certain shape of the workpiece or blank of the stamping method is the drop; conversely, to get the one with holes is punching. The deformation process of sheet separation is divided into three stages: elastic deformation stage, plastic deformation stage, shearing stage.
2, bending: bending is mainly done by the bending machine or by hand. Sheet in the bending process, the outer layer of tensile stress, the inner layer of compressive stress, from pull to pressure between a transition layer is not subject to both tension and pressure called the neutral layer; neutral layer in the bending process and the length of the bending process before the same, remain unchanged, so the neutral layer is the calculation of the bending length of the benchmark.
3, sheet metal parts of the connection: common sheet metal parts of the cold working process of the connection methods are: bite joint connection, riveting, welding, screw connection, pre-embedded (expansion) and so on.
Three, assembly requirements
Design of sheet metal parts should be considered when assembling.
High-volume assembly, should be less time-consuming cost of some of the structure, try to use the mold stamping into the snap, protruding platform and other installation methods.
Small batch production, consider less. Our company produces products, all belong to the small batch, only need to consider the sequence of assembly, assembly methods.
Four, cost requirements
Large production, it should shorten the assembly cycle, so that the assembly costs as low as possible, you can use the mold stamping and forming production.
Small batch production, as far as possible with some simple assembly.
Fifth, the choice of materials
Generally, we use sheet metal parts are thin steel, the use of cold-rolled or hot-rolled method of rolling. As noted in the different uses, the thin steel materials are mild steel, stainless steel, some also in the thin steel plate is coated with a layer of non-ferrous metal film, called thin coated steel (such as galvanized steel, lead-plated steel, tin-plated steel), and so on, and there are also used in the aluminum plate. Galvanized steel sheet is usually also called white zinc plate, has a strong corrosion resistance and beautiful surface features, its surface has a galvanized layer crystallization pattern. Galvanized steel can be used as long as it is accepted that the breaks in the steel sheet after processing are not corrosion resistant. Our company's products are generally placed in an indoor environment, there will not be a strong corrosive situation, you can use galvanized steel.