Assemble dimension chain

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One, basic idea assembles dimension chain is product or component in rigging a process, by the concerned dimension of relevant spare parts (the surface or axial space distance) or mutual position affects (parallelism, verticality or coaxial are spent etc) the dimension chain that forms. Its are basic the feature is to have close quality, namely one closes annulus and a certain number of the dimension chain that compositive annulus place makes is shown close graph, if pursue 11 - 4b place is shown. Its seal closed circuit is not the dimension on spare parts or component, differ however the relative position dimension of the surface of spare parts or component or axes space, it cannot change independently, assemble a process to be formed finally however, it is namely assemble precision, if pursue 11 - 4 medium A0. Its form link each is not to be in same a dimension on the spare parts, concern dimension with what assemble each part that precision concerns to go up however, if pursue 11 - 4 medium A1, A2 and A3. Assemble dimension chain the definition of each annulus and feature. Apparent, a2 and A3 are to add annulus, a1 is to decrease annulus. Assemble dimension catenary to be able to divide roughly according to the geometrical feature of each annulus and located dimensional position for: Linear dimension catenary, angle dimension catenary, planar dimension catenary and dimensional size catenary. Common is before two kinds. 2, those who assemble dimension chain build, linear dimension catenary (linear dimension catenary) 　 application assembles dimension to catenary is analysed and be solved assemble precision problem, it is above all find out and build dimension chain, seal closed circuit certainly namely, find out each in order to seal closed circuit to form link for the basis, the technique that assures to assemble precision certainly next and have necessary consideration. Find out and build the measure that assembles dimension chain to be as follows: (one) seal closed circuit certainly in rigging a process, the assembly that the requirement assures precision seals closed circuit namely. (2) find out compositive annulus, the picture assembles dimension catenary to pursue from seal one aspect of the matter of closed circuit random to begin, along the positional direction that assembles precision requirement, as ordinal as the dimension of each spare parts that assembles precision to concern end to end, until seal closed circuit till another end is conterminous, form to close the dimension graph of form, each dimension on the graph are compositive annulus namely. (3) after the property of compositive annulus draws differentiate to assemble dimension catenary to pursue, the character that forms link by definition differentiate - add namely, decrease annulus. Building when assembling dimension chain, except contented close quality, outside dependency principle, still should accord with following requirement. 1.

Compositive annulus counts least principle to set out from craft angle, in the structure already affirmatory circumstance falls, when tagging spare parts dimension, should make a part only a dimension enters dimension chain, comprise annulus amount to be equal to amount of concerned spare parts namely. If pursue 11 - 5a place is shown, the axis has A1 only a dimension enters dimension chain, it is correct. 10 - the tagging of 5b in the law, the axis has A, B two dimension enter dimension chain, it is incorrect. 2.

Press the different position that seals closed circuit and direction, build respectively assemble dimension chain. The worm deputy structure that exemple as usual sees, to assure normal clench the teeth, worm deputy the distance of two axes (clearance of clench the teeth) , planar symmetry all has particular demand among worm axes and worm wheel, this is direction of two different positions assemble precision, because this needs,build respectively in two different way assemble dimension chain. 3, the computational 　 that assembles dimension chain (one) computational type 　 1. the basic measure of foregone composition annulus and deviation generation enter numeration formulary, beg the basic measure error that gives a closed circuit, calculation is simpler no longer give uncecessary details. 2. Counterplot algorithm is foregone the basic measure that seals closed circuit and deviation, beg the basic measure that forms link each and deviation. The introduction uses below " harmonious annulus " solution calculates the basic measure that assembles dimension chain: In forming link, the choice compares easy treatment or rarer composition annulus is restricted to regard as in treatment " harmonious annulus " its computation process is the common difference that defines other annulus by economical accuracy first and deviation, use formulary cipher out next " harmonious annulus " tolerancepublic errand and deviation. Concrete step sees crossing-over assembles law example. 3. Intermediate numeration is foregone a closed circuit and the basic measure that form link and deviation, beg the basic measure of another composition annulus and deviation, calculation is simpler also no longer give uncecessary details. No matter which kind of circumstances, its solution calculates a method to have two kinds, namely minimax law and probability law. (2) computational method 　 1.

The computational method formula that minimax law assembles dimension chain with minimax solution and the formula that technology measure catenary solves in the 3rd chapter (3-21) ～ (3-33) identical, be omitted here. 2.

Probability law the advantage of minimax law is simple and reliable, its defect is the computational formula that from extreme circumstance next derivation setting out give, more conservative, the public errand that should seal closed circuit is lesser, and the number that forms link relatively a long time, the public errand that comprises annulus to share each is very small, make machine difficulty, production cost raises. Production carries out a proof, when machining a batch of spare partses, actually border dimension is in tolerancepublic errand of the part intermediate is most, and the spare parts that is in ultimate size is few number, and a batch of spare partses are being assembled in, especially the assembly to catenary of much annulus dimension, the each composition annulus of same part, be in ultimate size circumstance fitly, more scarce. Accordingly, be in group by group, mass-produced in, should assemble precision the demand is high, and the number that forms link relatively a long time, solution of applied probability law calculates assemble dimension chain more reasonable. Probability law and the distinction with the formulary calculation that minimax law uses are only on the computation that seals closed circuit public errand, other is identical. (1) a closed circuit public errand of minimax law: The T0 in type -- seal closed circuit public errand; Ti -- compositive annulus public errand; M -- form link several. (2) probability law seals closed circuit public errand: The T0 in type -- seal closed circuit public errand; Ti -- compositive annulus public errand; M -- form link several. CNC Milling CNC Machining