Talk about the design of semifinished product dimension
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3)=10 ± 9.
If 6(mm) (is calculated by probability law, criterion EE1=10 ± 4.
8mm) semifinished product each design is standard all be treatment when this workpiece thick fiducial place of the 1b that be like a graph is shown, semifinished product dimension is BM, CM, DM, EM, we still are calculated the rough machining surplus of E face. The measurement formula below this circumstance is EE1 → EMB1C1E1, get EE1=EM-MB1+B1C1+C1E1=(170 ± from this 1.
± of 5)-(610 ± 1)+(150 0.
3)+(300 ± 0.
3)=10 ± 3.
If 1(mm) (is calculated by probability law, criterion EE1=10 ± 1.
85mm) can see as a result from above computation, semifinished product presses the design form of graph 1b, only EM of dimension of a semifinished product affects EE1 of rough machining surplus, and the design form that semifinished product presses graph 1a, EC of dimension of 3 semifinished product, CB, BM affects EE1 of rough machining surplus. Accordingly, by graph 1b dimension of design semifinished product can make public errand of rough machining surplus is reduced greatly. Use same method to be able to undertake analytic computation to the rough machining surplus of other side, can get same conclusion, accordingly, this conclusion has common sense. The position error between face of 3 blame treatment and treatment face analyses to in an attempt to 2 for exemple, the N of → of P1 of ⊥ of positional relation N that analyses N of blame treatment face and P1 area... P1 of ∥ of D1 of ⊥ of M ⊥ B1, analyse with above surplus identical, if the positional design in face of the N in semifinished product graph is standard,be M face (M ⊥ N) , criterion P1 of ∥ of D1 of ⊥ of B1 of ⊥ of M of ⊥ of N of → of N ⊥ P1, only position error of this one semifinished product affects N ⊥ M N ⊥ P1, otherwise will more semifinished product position error affect N ⊥ P1. For example, graph of hypothesis semifinished product presses the design form of part drawing, of face of semifinished product N fiducial for D face (D ⊥ N) , of D face fiducial for E face (E ⊥ D) , of E face fiducial for M face (M ⊥ E) , criterion P1 of ∥ of D1 of ⊥ of B1 of ⊥ of M of ⊥ of E of ⊥ of D of ⊥ of N of → of N ⊥ P1, have D ⊥ N, e ⊥ D, m ⊥ E3 P1 of ⊥ of N of influence of semifinished product position error. Consider on one hand from the position error that reduces blame treatment face and treatment range consequently, to semifinished product each position error that put forward what still should use in order to machine this when semifinished product is thick fiducial for fiducial. In the analysis of above, what N represents is face of aleatoric blame treatment, what P1 represents is aleatoric treatment face, so the conclusion above also has common sense. No matter,principle of design of dimension of 4 semifinished product can see through the analysis above from reduce regard of respect of public errand of surplus of each rough machining, or from reduce the position error respect between blame treatment face and treatment face to consider, the author thinks to answer to regard semifinished product as each design with thick datum plane fiducial. "Each dimension designs semifinished product fiducial (include the place fiducial) should use treatment as far as possible what use when this semifinished product is thick fiducial " call semifinished product dimension to design a principle (call a principle) below. Follow this principle, it is to be able to make semifinished product common difference of each rough machining surplus is the least, can choose lesser mental allowance thereby, reduce material to use up: 2 it is to be able to make the relative position size between blame treatment face and treatment face the exactest, in order to raise the treatment precision of the spare parts. If two faces in part drawing do not need to machine,what ought to point out is, and part drawing is not treatment to these two there is dimension position demand between the face, criterion the tagging that the semifinished product dimension between this two sides should press part drawing means undertakes tagging. At present we just consider how to choose mental allowance of coarsen of thick fiducial ability when formulate machining craft change is the least and how can just assure to be not treatment the positional size between face and treatment face is the exactest, make through the analysis above we realise when to designing semifinished product, answer mature this. Pressing a principle to design semifinished product dimension to be in practice is feasible, this needs us to be made in the mould of semifinished product reach semifinished product to produce craft to reach principle birth semifinished product should be pressed as far as possible in examining (the pattern that with fast prototype production technology creates is very easy according to principle) . Of course, it is very difficult that some semifinished product produce craft to press a principle, also may not blame presses a principle cannot, but we should press a principle as far as possible, in order to make as far as possible the dimension between surplus of little rough machining of impact of semifinished product measure and blame treatment face and treatment face. The dimension of the semifinished product plan that devises by the principle and part drawing can compare a gender poorer, dimension calculation is more complex also, but and reduce material to use up, raise photograph of spare parts precision to compare, these cost are worthiness, and dimension of CAD semifinished product makes such dimension conversion won't become an obstacle. Actually, we develop " software of calculation of technology measure formula " the content that had contained this respect. The principle that the author advances devises semifinished product measure, it is to be able to reduce rough machining surplus, 2 it is to be able to raise the dimension position precision between blame treatment face and treatment face. The promotion application of this principle reduces material to use up to mechanical manufacturing industry, raise product quality to have important sense, at the same time this principle also can assist the basic principle that semifinished product dimension designs as the computer. CNC Milling