The concept of dimension chain in the hottest proc

Concept of process dimension chain

concept of dimension chain

We must master the important concept of dimension chain principle

. Dimension chains are interconnected, arranged in a certain order, and closed dimension chains. Including closing ring and composition ring. According to the influence of its constituent ring on the closed ring, it can be divided into increasing ring and decreasing ring. Dimension chain diagram is a diagram in which the corresponding rings in the dimension chain are marked on the schematic diagram with dimensions or symbols

calculation of dimension chain

Master the calculation steps and formulas of linear dimension chain:

(l) Positive direction calculation: the method of calculating the closed ring according to the known size of each constituent ring. The result of this kind of calculation is the only shared platform like Jin min

. (2) Reverse calculation: when the size of the closed ring is known, calculate the size of the constituent ring. The purpose of calculation is to reasonably allocate the tolerance value of the constituent ring to each constituent ring with important practical significance and far-reaching historical significance. Its calculation result is not unique, only the best

. (3) Intermediate calculation: given the size of the closed ring and part of the component ring, calculate the various sizes of the other unknown size rings. As a result, there is a problem of selecting the best scheme with reasonable allocation of tolerance values

. The first two problems are often encountered in product design. When the external force is small, the process design is often an intermediate calculation problem

. It is required to master

. It is to solve the problem of dimension and tolerance when the datum does not coincide (key point). The machining accuracy needs to be adjusted through calculation: when the tolerance of the closed ring is greater than the tolerance of the constituent ring of the known size, the machining accuracy requirements of this process will increase; When the closed ring tolerance of the portable myebox analyzer is less than or equal to the component ring tolerance with known size, it is necessary not only to improve the accuracy of this process, but also to improve the processing accuracy of the previous process. Improving the accuracy may cause the adjustment of the process and measurement methods

. "Dimension conversion when positioning datum and design datum do not coincide", we should master the conclusion of "tolerance and tolerance zone changes caused by datum misalignment"

. "The determination of process dimension and its tolerance when taking the surface that still needs to be processed as the process benchmark" is very similar to "the determination of process dimension and its tolerance when the depth of surface treatment layer needs to be guaranteed". Master the calculation method of similar problems

. Understand the conclusion that the machining allowance by spark grinding depends on the technical level and habits of operators. (end)