抬牙连杆挡圈是我厂从日本引进的高速平缝机上的零件(见图1),材料为65Mn钢,料厚1.2毫米,中等批量生产,零件虽然精度要求不太高,但有两处超出了一般冲裁件的工艺许可值:①槽宽B=1.2mm,与料厚t的比值为B/t=1,而一般对于硬钢(65Mn)允许值为B/t≥1.5②两个φ2小孔的边缘离外形的最小距离为a=1mm,与 Lifting teeth connecting rod ring is my factory imported from Japan, high-speed sewing machine parts (see Figure 1), the material is 65Mn steel, material thickness 1.2 mm, medium batch production, parts although the accuracy is not too high, but there are two Department exceeded the allowable value of the general stamping parts: ① groove width B = 1.2mm, and the material thickness t ratio B / t = 1, and generally for hard steel (65Mn) allows the value of B / t ≥ 1.5 ② The minimum distance between the edges of the two φ2 holes from the shape is a = 1mm, and