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在机械加工中,工件常采用两孔定位,在设计相应的夹具中,就采用两销一面定位。这样加工出的工件,易于保证质量,夹具制造也方便。在设计夹具时,为使圆柱销和菱形销能同时装进工件孔中,必须使菱形销的圆弧部分宽度做得适当,以便能补偿在最坏情况下(两孔做到最小尺寸,两销做到最大尺寸)的误差间隙。根据这一原理,则有如下公式:b≤(φ_2·△_(2min)/2(δ_1+δ_2)-△(1min)式中:b——菱形销圆弧部分宽度(图1中AB)φ2——菱形销直径名义尺寸△1min——菱形销和孔配合的最小间隙δ_1——工件上两孔间的距离公差δ_2——夹具上两销间的距离公差在最坏情况下,装配
In machining, the workpiece is often used to locate two holes in the design of the corresponding fixture, the use of two pins positioning side. This processed workpieces, easy to ensure quality, fixture manufacturing is also convenient. In designing the fixture, it is necessary to make the width of the arcuate portion of the rhombus pin appropriate so that the cylindrical pin and the rhombus pin can fit into the workpiece hole at the same time, so that in the worst case scenario Pin to achieve the maximum size) of the error gap. According to this principle, there are the following formulas: b ≤ φ 2 · Δ 2min / 2 δ 1 + δ 2 - Δ 1min Where: b - the width of the arcuate portion of the diamond pin (AB in Fig. 1) φ2-- nominal diameter of the diamond pin △ 1min - diamond pin and the hole with the minimum clearance δ_1 - workpiece on the hole between the two tolerances δ_2 - fixture on the distance between the two pins In the worst case, the assembly