CN112833831A

CN112833831A - Coplanarity parameter detection method

Info

Publication number: CN112833831A
Application number: CN202011630739.2A
Authority: CN
Inventors: 朱运; 李丽; 邢凤文
Original assignee: Aecc Changchun Control Technology Co ltd
Current assignee: Aecc Changchun Control Technology Co ltd
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2021-05-25

Abstract

A coplanarity parameter detection method relates to the technical field of part parameter tolerance detection, and solves the problem that geometric dimension tolerance grades of metering detection equipment and product parts cannot be matched in the prior art, and comprises the steps of selecting a measuring probe according to the size and the shape of the parts, and establishing a common plane by taking a plurality of points in two measured planes E and E1 by adopting the measuring probe; the common plane is aligned to the positive direction of a Cartesian coordinate system Z, and a first point taken in two measured planes E and E1 is set to be zero; taking 6 points including the first point from the two measured planes E and E1, and automatically measuring by using a three-coordinate measuring machine; and judging whether the detection is effective or not by reading the numerical value of the first point, respectively detecting the two detected planes corresponding to the other groups, obtaining the coplanarity parameter measurement results of the two detected planes, and ending. By the detection method, the detection capability of the part with the coplanarity tolerance of 0.002mm is realized.

Description

Coplanarity parameter detection method

Technical Field

The invention relates to the technical field of part parameter tolerance detection, in particular to a coplanarity parameter detection method, which is suitable for the field of coplanarity parameter detection when the precision of measuring equipment cannot be matched with the grade of part parameter tolerance.

Background

In modern measurement and detection work, geometric tolerance detection is an important position as a basic subject. In the field of aircraft engine finish machining, the situation that geometric measurement tolerance grades of metering detection equipment and product parts cannot be matched often exists, for example, a drawing marking coplanarity parameter is 0.002mm, according to the requirement of JJF (military industry) 8-2015 standard (the uncertainty ratio of a measured product to the measurement equipment is 4:1), the indication error of the measurement equipment is required to be less than or equal to 0.0005mm, the measurement equipment belongs to the highest precision grade of three-dimensional measurement in the world, and the detection problem needs to be solved under the condition that the existing hardware conditions of enterprises are not changed.

Disclosure of Invention

The invention provides a coplanarity parameter detection method, aiming at solving the problem that geometric dimension tolerance grades of metering detection equipment and product parts cannot be matched in the prior art.

A coplanarity parameter detection method is realized by the following steps:

step one, electrifying a three-coordinate measuring machine;

selecting a measuring pin according to the size and the shape of the part, and vertically placing the part on a workbench;

step three, respectively adopting a measuring needle to take a plurality of points in two measured planes E and E1 to establish a common plane; using the common plane to align the corresponding Z direction of the Cartesian coordinate system, and setting zero at a first point taken in the two measured planes E and E1;

step four, 6 points including the first point are taken from the two measured planes E and E1, and a three-coordinate measuring machine is adopted for automatic measurement;

step five, reading the numerical value of the first point, and if the numerical value is less than 0.0004mm, taking the difference between the maximum value and the minimum value of the 6 points as E, E1 two-plane coplanarity; executing the step six;

if the numerical value of the first point is more than or equal to 0.0004mm, the measurement process is invalid, and instruments, measurement environments and operation methods need to be checked; returning to the third step to measure again;

and step six, respectively detecting the two measured planes corresponding to the other groups, obtaining the coplanarity parameter measurement results of the two measured planes, and ending.

The invention has the beneficial effects that: by the detection method, the detection capability of the part with the coplanarity tolerance of 0.002mm is realized.

The detection equipment adopted by the invention is cheap, the method is simple and feasible, and the operation is convenient.

The detection method of the invention can also provide technical reference for low-cost detection work of other parameters.

Drawings

Fig. 1 is a schematic view of typical parts of a valve sleeve.

Detailed Description

Referring to fig. 1 for the description of the present embodiment, the valve housing of fig. 1 has 8 sets of through square holes, respectively E, E1; F. f1; G. g1; H. h1; l, L1, respectively; m, M1, respectively; n, N1, respectively; p, P1, all are formed by linear cutting one-step processing, the coplanarity is required to be measured to be 0.002mm, and T in figure 1 is the inner wall of the inner hole of the part. According to the requirements of JJF (military industry) 8-2015 standard requirements (uncertainty ratio of measured products to measuring equipment is 4:1), the indication error of the measuring equipment needs to be less than or equal to 0.0005mm, and the direct measurement of the parameters can be realized by a three-coordinate measuring machine at home and abroad (0.0004+ L/700) mm level at present. The definition according to coplanarity refers to the maximum deviation obtained by taking the plane formed by the three lowest pins of the part as a reference plane and comparing the rest pins with the reference plane. The theoretical detection method comprises the following steps: collecting coordinate values of a plurality of small end faces (points); finding three high points and determining an ideal base plane; and finding the lowest point to obtain the deviation value, namely the coplanarity. In the actual production process, three high points are difficult to find, so that a feasible scheme is designed in the embodiment. The method is realized by the following steps:

step one, electrifying a three-coordinate measuring machine;

step three, respectively adopting a measuring needle to take a plurality of points in two measured planes E and E1 to establish a common plane; the common plane is aligned to the positive direction of a Cartesian coordinate system Z, and a first point taken in the two measured planes E and E1 is set to be zero;

and step six, respectively detecting the other two corresponding measured planes to obtain coplanarity parameter measurement results of the two measured planes, and ending.

In the embodiment, aiming at a conventional (0.0014+ L/1000) mm-grade three-coordinate measuring machine, the detection work of the coplanarity parameter is finished by adopting equipment repetition precision and a method for confirming the measurement repeatability of the equipment. And comparing the final measurement result with a (0.0004+ L/700) mm grade three-coordinate measuring machine to calculate the En value of the laboratory, and confirming the result to prove that the measurement method is accurate and reliable.

The second embodiment is an example of a coplanarity parameter detection method according to the first embodiment:

a) opening a power supply, an air source and a computer host of the current three-coordinate measuring machine;

b) entering measurement software, and returning the instrument to a zero position;

c) selecting a proper measuring pin according to the size and the shape of the part, selecting a measuring pin of which the diameter of a measuring ball is less than phi 1.5mm and the length of a measuring rod does not exceed the measuring range of equipment, and verifying by using a standard ball;

d) vertically placing the part on a workbench, and roughly establishing a part coordinate system at a sampling point;

e) respectively using a measuring needle to take 4 points a1, a2, a3 and a4 in two planes to be measured E, E1, and establishing a common plane by using the 4 points;

f) aligning to the positive direction of a Cartesian coordinate system Z by using a common plane, and zeroing a 1;

g) copying a1 point named as a5, including a5, taking 3 points in two planes E, E1 respectively, and sequentially named as a6, a7, a8, a9 and a10, and then carrying out automatic measurement;

h) reading the value of a5 at a point, if a5 is less than 0.0004mm, a5, a6, a7, a8, a9 and a10, wherein the difference between the maximum value and the minimum value of the 6 points is E, E1 two-plane coplanarity;

i) if a5 is more than or equal to 0.0004mm, the measurement process is invalid, and the instrument, the measurement environment, the operation method and the like need to be checked, and the measurement is carried out again.

j) Repeating the steps e) f) g) h) i) above, and respectively detecting the other groups of square holes as F, F1; G. g1; H. h1; l, L1, respectively; m, M1, respectively; n, N1, respectively; p, P1.

In this embodiment, a conventional (0.0014+ L/1000) mm-scale three-coordinate measuring machine is used for measurement, and the measurement results are shown in table 1 below:

TABLE 1

a5	a6	a7	a8	a9	a10
						0.0003	0.0008	0.0010	0.0010	0.0018	0.0014

The coplanarity of the parts was 0.0015 mm.

The measurement method described in the present embodiment is verified:

for a few laboratory-developed comparison methods, the method is generally applied to a laboratory comparison method for detecting/calibrating laboratory self-development, and an En value is often adopted for evaluation:

when the absolute value of the En value is less than or equal to 1, the comparison result is satisfied, and the En value passes;

when the absolute value of the En value is more than 1, the comparison result is unsatisfactory and fails.

Wherein E_nThe value is calculated by the formula of,

by adopting the detection method of the embodiment, the measurement result of the (0.0014+ L/1000) mm three-coordinate measuring machine is obtained

U₁1.838 μm; (0.0004+ L/700) mm scale three-coordinate measurement result is

U₂0.0003 μm. See table 2 below for details.

TABLE 2

Error in the indication of the device	Average measurement result (. mu.m)	Uncertainty of measurement result (. mu.m)
			(0.0014+L/1000)mm	0.0011	1.838
(0.0004+L/700)mm	0.0015	0.0003

To obtain E_nWhen the ratio is 0.0002 ≤ 1, the comparison result is satisfied.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A coplanarity parameter detection method is characterized by comprising the following steps: the method is realized by the following steps:

step one, electrifying a three-coordinate measuring machine;

step three, respectively adopting a measuring needle to take a plurality of points in two measured planes E and E1 to establish a common plane; the common plane is adopted to align the corresponding positive Z direction of the Cartesian coordinate system, and a first point taken in the two measured planes E and E1 is set to be zero;

step four, taking 6 points including the first point from the two measured planes E and E1, and automatically measuring by using a three-coordinate measuring machine;

step five, reading the numerical value of the first point, and if the numerical value is less than 0.0004mm, taking the difference between the maximum value and the minimum value of the 6 points as the coplanarity of two measured planes E and E1; executing the step six;

2. A coplanarity parameter detection method according to claim 1, characterized in that: and in the second step, a measuring pin with the diameter of the measuring ball less than phi 1.5mm and the length of the measuring rod less than or equal to the measuring range of the equipment is selected for the part, and a standard ball is adopted for checking.