Time：2020-01-08| Author：Admin
Shape surface The shape surface refers to the surface that constitutes the basic shape features of a mold part. Generally, the external surface is the outer edge surface of the mold part. These outer edge surfaces are mostly rectangular bodies composed of planes or rotating bodies composed of cylindrical surfaces and conical surfaces, and sometimes also include two-dimensional curved surfaces and three-dimensional curved surfaces.
2) Forming surface Forming surface refers to the surface that directly determines the shape, size, and accuracy of product parts in the mold and related surfaces that coordinate with these surfaces. For example, the working surface of the die, the punch in the punching die, and the surface of the hole such as the discharge plate and the fixing plate related to the coordination of the working surface. The forming surface of the bending die convex die shown in Figure 7-3 refers to a two-dimensional curved surface composed of dimensions such as R4.8, R7.8, 86 °, and 33 °. Generally, the shape of the forming surface is relatively complicated, the dimensional accuracy is high, and the surface roughness value is small, and there are many heat treatment requirements. The consistency and coordination of the forming surface of each related part have stricter requirements. The processing of the forming surface is one of the focuses and difficulties of the mold process.
3) Structural surface Structural surface refers to the surface that plays the role of positioning, guiding, distance setting, limiting, coupling, driving, etc. in the mold. The surfaces of the two cylindrical pin holes of the bending die punch shown in Figure 7-3 are structural surfaces, which are positioning and fixing surfaces connected to the die handle. The structure surface in the mold plays a very important role in ensuring the relative size and position accuracy of each part and the reliability of the connection and mutual movement. The shape of the structure surface is various, and the materials and heat treatment requirements of different parts are different. In the process arrangement, it should be treated differently according to the role of the structural surface of each part and the relationship with other related parts. 2. Processing analysis of various surfaces
1) Processing of contoured surfaces The processing of various mold parts starts with the processing of contoured surfaces and lays the foundation for the subsequent processing of forming surfaces and structural surfaces. In the blank design and processing of mold parts, the machining allowance of the contour surface should be appropriate to avoid material waste and reduce subsequent processing workload. For forgings and casting blanks, the necessary annealing and aging heat treatment should be performed during the blank processing stage to reduce the internal stress of the material and prepare the metallographic structure for subsequent processing. Among the external surfaces of the mold parts, some surfaces are the scribe line and the reference plane for dimensional processing of subsequent processing, and some are the joint surfaces between the parts, the parting surface of the mold, and the mounting surface of the mold and the machine tool . As for the plane contour surface that will be the scribe plane, reference plane, joint plane, parting plane, and mounting plane, the surface roughness Ra ≤ 0.8 μm, and the remaining plane contour surfaces Ra = 6.3 μm may be sufficient. The accuracy of the shape and position of the plane shape surface requires the flatness of the plane and the parallelism and perpendicularity between the planes. Some of these shape and position accuracy requirements have been specified and required in the mold design, and some are required to be guaranteed during processing due to the needs of the part processing technology. See Table 7-1 for the requirements of parallelism between general planes. See Table 7-2 for the requirements of verticality between planes. The flatness of the plane is 0.02: 300. The machining of flat surface can be planed and milled on a bull's-head planer, end mill, and gantry planer to remove most of the machining allowance on the blank. From the perspective of production efficiency, large-scale planes are mostly planed by gantry planers; medium-scale planes are mostly planed by bull head planers; medium- and small-scale planes are mostly milled by end mills. Through the above processing, the basic shape and size of the flat surface can be obtained, but the flat surface is relatively rough, and the parallelism and perpendicularity are relatively low. Then the surface grinding of the subsequent process can achieve the specified size and surface roughness and parallelism. , Verticality requirements. For the perpendicularity requirements of adjacent surfaces, it is generally ground and clamped on a surface grinder with a special fixture to ensure the perpendicularity requirements. The accuracy check can be measured by a square ruler. For inlays and tiles of complex shapes with rectangular and square shapes, six planes of surface grinding should be generally performed to meet the requirements of parallelism and perpendicularity to ensure the needs of subsequent scribing, processing and measurement. For the outer surface of the outer cylinder or cone, turning is performed on a lathe. Generally, the surface is turned while turning the outer rotating surface by one clamping, and drilling, reaming, boring can be performed at the center. Ensure the coaxiality and perpendicularity of the relevant surfaces. For larger size and quality parts, they are mostly processed on vertical lathes, which is not only easy to find and install, but also easy to ensure the processing accuracy; for medium and small parts, more ordinary lathes are used for processing; for slender shaft parts Due to the poor rigidity, you should use the method of clamping and support at both ends to turn; for the rotating body parts whose busbars are curved, CNC lathes are often used for processing, and profile templates are used for inspection.
2) Forming surface processing There are many classification methods for forming surfaces. Considering the following aspects from the perspective of mold manufacturing process:
(1) According to the solid material of the forming surface, it is divided into external and internal profiles.
(2) When the inner surface is a through hole, it is called a cavity; when the inner surface is a blind hole, it is called a cavity.
(3) According to the different cross-sectional geometric characteristics of the profile, it is divided into circular cross-section and special-shaped cross-section (curved surface).
(4) According to the number of variable coordinate points of a surface, it is divided into a two-dimensional surface (a planar surface) and a three-dimensional surface (a solid surface). As for the processing method of the forming surface, according to the different processing mechanisms, it can be divided into three categories:
(1) Metal cutting methods relying on mechanical force cutting are the oldest and most widely used processing methods, and they are also the basic methods of mold parts .
(2) The special processing method that uses electric energy, thermal energy, light energy, and chemical energy as power is a new type of processing method with great development prospects, and it has become more and more important in the processing of mold parts.
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