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Discussion on the most popular fake waste products

2022-10-12

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Discussion on the problem of fake waste products

1 the conditions for the generation of fake waste products are shown in Figure 1. L1 and L2 are the design dimensions. When machining the C-plane, for the convenience of clamping and processing, the d-plane is used as the positioning datum for processing, and the process dimension is A2. Because the positioning datum (process datum) does not coincide with the design datum, the process dimension is calculated by using the process dimension chain

according to the dimension chain shown in Figure 2, it can be obtained: 2= (a1-a ∑) - △ L1 - △ l2

let l1=500- 1mm l2=200+0.150mm

then a2= In Figure 2 of 15mm, if a2=29.95mm is processed, it obviously exceeds the tolerance range of the process dimension, and it should be "scrap". However, if a1=50mm at the same time, l2=20.05mm. Although A2 is out of tolerance, L2 is still within the tolerance range of the design dimension, and this part is a fake scrap. To sum up, when processing a workpiece with benchmark conversion, that is, the process benchmark does not coincide with the design benchmark, there may be fake scrap. 2. The range of fake waste products can be determined by using the process dimension chain in reverse. As shown in Figure 1, the dimension chain can be obtained by taking the process dimension A2 as a closed ring and A1 and a Σ as a constituent ring: Figure 1 divides A2 into three areas. As shown in Figure 3: where: is the genuine product area, is the area that may produce false waste, and is the waste area. A21= (L1-L2) - △ l1- △ L2 is the genuine product area

a22= (L1-L2) 0- △ L1 is the area that may produce false waste products

a23= (L1-L2) - △ l2- (△ l1+ △ L2) is the area that may produce false waste products. 3 correctly distinguish true and false waste products. For the workpiece whose process size is in the area that may produce false waste products, it is necessary to identify whether it is true waste products, First, the dimension between the machined surface and the design basis of the surface (i.e. the design dimension) can be measured directly. If the dimension does not exceed the tolerance range of the design dimension, the workpiece should be genuine, otherwise it is scrap. If the size is not easy to measure, it can be measured that the construction of the project in the size chain is the size of the main gripper that promotes the revitalization of Hejin, and the size is calculated to determine whether it is authentic because of the large error in the front of each scale range of the dial. 4. Process measures when calculating the process size, if there is a benchmark conversion, the process personnel should calculate the process size according to the size chain, and at the same time, calculate the range of fake waste products, and fill it in the process documents. The operators or inspectors are required to identify those workpieces whose size is in the area where fake waste products can be generated according to the above method, so as to improve the production efficiency. Selected from mechanical engineer