Research on automatic search technology of parting

2022-10-05
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Research on automatic search technology of injection mold parting line

Abstract: a method of automatic search of mold parting line is proposed. This method first determines the plane perpendicular to it according to the demoulding direction, and projects the plastic part to this plane to obtain the main contour of the mold parting line, then establishes the mapping relationship between the main contour line and the edge line and vertex projection on the surface of the part, from which a variety of candidate parting lines can be obtained. Finally, according to the evaluation factor of the parting line, the optimization objective function value of each parting line is calculated to determine the best parting line. The example test shows that this method has high efficiency and practicability

key words: injection mold; Parting line; Projection mapping; Optimization

in the design process of injection mold, we must first determine the reasonable demoulding direction and parting line, and then generate the parting surface from the demoulding direction and parting line, which are the follow-up mold 3 Calibrated friction force: used to calibrate friction force (the basis of detailed design has been set before leaving the factory. Moreover, according to practical experience, the demoulding direction, parting line and the parting surface determined by them are several main parameters that affect the mold cost. Because the determination of demoulding direction, parting line and the shape of parting surface determined by the parting line will affect the complexity of the mold structure, and then affect the cost of the mold. Unreasonable demoulding direction, parting line design and unreasonable parting Face shape is likely to lead to the failure of mold design. Therefore, in the process of mold design, it often takes a long time to determine these three parameters. If the demoulding direction and parting line of the mold can be automatically determined by computer, and they can generate a reasonable parting surface, it will undoubtedly play an important role in reducing the cost of injection mold and improving the automation of injection mold design

due to the needs of mold design automation and intelligence - until the 1990s, people began to pay attention to the research of automatic parting technology. F automatic parting technology mainly includes three aspects: automatic determination of mold demoulding direction, automatic determination of mold parting line and automatic generation of mold parting surface. The demoulding direction is the basis of the automatic determination technology of parting line and the automatic generation technology of parting surface, and the parting line determines the shape and complexity of the parting surface, so the automatic determination of parting line is the key to realize the automatic parting technology of injection mold. According to the published literature, the research on the automatic determination technology of the mold parting line is based on the characteristics. Let's talk about the relevant knowledge recognition and rule discrimination method of the clamping mode of the fixture of Jinan assay tensile testing machine. Zhu Xilin and others proposed to determine the demoulding direction by calculation based on the concept of approaching cone proposed by antoniol and others, and to determine the parting line by projection method. Tan et al. Proposed two methods to automatically determine the parting line. One method is to generate component lines by triangulating the surface of plastic parts. This method first triangulates the surface of the plastic part according to the demoulding direction, and divides these triangular patches into visible, invisible and degraded surfaces. The visible and invisible common edges on the plastic part form the constituent edges of the parting line, and the parting line is obtained by reorganizing these edges. This method is inefficient because it involves the division of triangular patches on the surface of plastic parts. Another method is to generate component lines by slicing the plastic model. However, this method has some shortcomings, such as inaccurate position of parting line caused by the problem of discrete accuracy. The main performances, main regulations, main functional performance requirements, main reliability/durability requirements, main environmental test requirements and the Countermeasures in the above aspects of auto parts are summarized; "Research on discontinuous carbon fiber reinforced composites and their utilization" was presented by Professor Wan yizao, director of the Institute of composite materials of Tianjin University. Nee et al. Proposed a method to automatically generate parting lines by grouping plastic surfaces and extracting the largest side ring. This method has high efficiency, and the disadvantage is that it does not exclude the side concave that does not contribute to the determination of the parting line, nor does it consider the situation when the parting line is not completely composed of plastic parts, and only one parting line is determined. Weinstein et al. Proposed a method to determine the position of the parting line by dividing the concave convex region of the plastic surface. Ravi and Srinivasan proposed nine criteria for computer-aided parting line and parting surface design to help users determine a reasonable parting surface. They also gave a method to determine the parting line, that is, first calculate the outline of the projection of the plastic part on the plane perpendicular to the demoulding direction, and then stretch the contour line along the demoulding direction. The parting line is the intersection of the stretched body and the plastic part. Ganter and tuss presented a computer-aided algorithm for the generation of parting line of pouring mold. This method uses the parting surface selected by the user to cut the workpiece to obtain a plane parting line, but this method is only limited to the determination of the plane parting line

Zhou et al. Proposed a method to automatically generate the parting line of plastic parts by grouping the surface of plastic parts and extracting the maximum side ring on the premise that the mold release direction and the side concave characteristics of plastic parts are known. In this method, all non side concave surfaces of the plastic parts are grouped according to the geometric characteristics and topological relationship of the plastic parts in the demoulding direction 7 of the mold, and then the maximum side rings of different surface groups are extracted to obtain two candidate parting lines. Finally, the evaluation factors of various parting lines are calculated by using the optimization objective function to determine the optimal parting line of the plastic parts. This method is essentially an improvement on the method of nee et al. It can solve the automatic determination of the parting line of plastic parts composed of planar and quadric surfaces, but it is not suitable for plastic parts with free-form surfaces. On the basis of summarizing the previous work, this paper proposes a method to determine the mold parting line by computer automatic search and Optimization on the premise that the mold demoulding direction and the plastic part side concave feature are known

1 related terms

the core of injection mold is the cavity and core of parts. Generally, the cavity refers to the external shape of the molded injection part, and the core refers to the internal shape of the molded injection part. The demoulding direction is a pair of opposite directions that separate the cavity and core. Parting line refers to the boundary line where the new risk points of plastic parts and molds come into contact one after another, which is related to the direction of demoulding. The parting surface refers to the surface where the cavity contacts the core. It is related to the parting line, which should include the parting line. Figure 1 is an example of related terms

for the convenience of expression, this paper introduces the concepts of main projection plane and main contour line, which are defined as follows:

main projection plane: the plane perpendicular to the demoulding direction, which is recorded as FZ

main contour line: the outer contour line of the projection of the plastic part on the main projection plane, that is, the projection of the parting line on the main projection plane, which is recorded as LZ

2 automatic search of parting line

the basic idea of the automatic search algorithm of parting line is: according to the demoulding direction and side concave characteristics, first project the plastic part along the demoulding direction PD to the main projection plane FZ to obtain the main contour line>

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