Discuss to what compensation of the biggest hypostatic principle is worth

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The biggest hypostatic principle is to become the element that be measured and fiducial element deviate are the biggest when hypostatic dimension, form the principle of a kind of public errand that tolerancepublic errand can obtain compensation to be worth. The biggest hypostatic principle basically is used at asking to have to be able to assemble sexual spare parts to go up, if box is built, flange dish the spare parts that waits to be received with Kong Lian. To these spare partses cooperate property not to have strict requirement, but the requirement is united in wedlock between have enough space amount, enough compensation form error, assure to be able to assemble a gender, facilitate thereby assemble. But, it is at present in national level and document of certain science and technology, have the problem that is worth deliberate to the treatise of the biggest hypostatic principle, be like Hua Guoliang " interchangeability and measure a technology " in say: "Press regulation of the biggest hypostatic principle, the form that tags on the graph tolerancepublic errand value is the element that be measured given below the biggest hypostatic condition. When deviate of the element that be measured when the largest hypostatic size, form tolerancepublic errand value is attainable cost of a compensation. This compensation is worth the difference that is the largest hypostatic size and real measure. " the author thinks to say exactly should be: "This compensation is worth the absolute value of the difference that is the largest hypostatic size and real measure. " why to want such saying? Look please below two example: ? ? pursues 2 graphs are shown 1 times for one diameter φ 20, dimension public errand 0.

02, φ of linearity public errand 0.

The 01 axes that abide by the biggest hypostatic principle, the largest hypostatic size is this axis φ 20, if be measured,element is φ 19.

99, criterion linearity public errand can get a compensation is worth namely φ 20- φ 19.

99= φ 0.

01, that is to say axes can be in φ 0.

02 linearity public errand change inside the belt. The graph is shown 2 times for one diameter φ 10, dimension public errand 0.

02, φ of linearity public errand 0.

The 01 aperture that abide by the biggest hypostatic principle. The largest hypostatic size is this aperture φ 19.

98, if be measured,element is φ 19.

99, below this kind of circumstance, aperture linearity public errand will obtain a negative compensation to be worth namely φ 19.

98- φ 19.

99=- φ 0.

01, this kind of state is incorrect apparently. Appear afore-mentioned results, because need pair of the largest hypostatic position,be (MMC) with the largest hypostatic size (MMS) the meaning tries to make clear. The largest hypostatic position is aperture or axis have the material amount that allow to be most the condition when, the ultimate size below this condition calls the largest hypostatic measure, it is a general designation of the size of the biggest maximum of the size of the smallest maximum of aperture and axis. Accordingly, the largest hypostatic size of aperture is less than its real measure certainly, and the real measure that the largest hypostatic size of the axis is more than it certainly. Be in so the biggest hypostatic principle " the difference that this compensation cost is the largest hypostatic size and real measure " in the description, appearing to say to Kong Lai is result of the compensatory that lose a value, this does not accord with objective fact. Because this increases absolute value only, state ability so more rigorous. In addition, be in " machining craft design manual " , " GB collection the 7th " in waiting for a book, the explanation that concerns the biggest hypostatic principle explains, also have not rigorous place, the article is differ one give uncecessary details. CNC Milling