JPS61262610A - Measuring straightness of positioning table - Google Patents

Abstract

PURPOSE:To cancel a straightness error of a standard block to thereby increase a measuring accuracy by conducting a measurement three times by using the standard block and computing measured values by a computer. CONSTITUTION:The straightness of a positioning table in which a table 1 is moved by a drive motor 3 and a power transmitting screw 4 in an X direction while being guided by a guide 2 is measured by an air micrometer while the table 1 carrying thereon a standard block 5 with some straightness error. A system comprises the detector 8, controller 9 both of the air micrometer and a communication line 10 for automatically taking in measured values from the air micrometer in response to the command of a computer 7, and the like. A motor driver 11 is connected to a motor 3 peculiar to the positioning table and, further, the driver 11 drives the motor 3 in response to the command of the computer 7, the three time measurements are automatically performed. Then, by computing the measured values by the computer 7, the straightness can be measured with a high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for measuring the straightness of a positioning table.

[Conventional technology]

The straightness measurement of a conventional positioning table will be explained with reference to FIG. There are two methods for measurement: a method using a reference block and a method using a laser beam. However, since measurement using a laser is outside the scope of the present invention, a method using a reference block will be described. In the straightness measurement using a reference block, as shown in FIG. 2, K, a movable table 1 (hereinafter referred to as table) button, and a reference block 5 are placed on the table and moved in the X direction. At this time table 1
6t also fluctuates by a minute amount in the Y direction, and this fluctuation is measured by a displacement probe 6 fixed to the ground.

FIG. 3 shows the amount of table movement (
The relationship between illusion and displacement in the Y direction is shown below.This school of fish is defined by the distance l! between two straight lines. It is sandwiched by two straight lines that make it the smallest,
The conventional method for measuring straightness is to determine the straightness by the distance in the Y direction between these two lines (minimum area method).

[Invention b'--Problems and Objectives to be Solved] However, in the straightness measuring method using a reference block according to the prior art described above, the Y-direction displacement output from the displacement shape 6 in FIG. In addition to the straightness of the table positioning table to be determined, this is indicated by a two-dot chain line in the figure. It also includes a straightness error inherent to the reference block 5, and does not accurately represent the straightness of the positioning table. Especially in recent years, the range of movement is large (for example, 100m5) Kh7t
This allows for a high level of straightness that was previously unimaginable (
For example, ±1μ inertia] is now required, but in reality, it is difficult to manufacture a reference plate with high precision (high straightness) that can withstand such measurements. Very far apart.

Therefore, one object of the present invention is to provide a reference block with a straightness error b.
- Even if there is some error, the straightness error of the reference block can be canceled and the true straightness of the positioning table can be determined by properly using the same reference block and calculating the Va% measurement value with a computer. It is an object of the present invention to provide a straightness measurement method that provides a straightness measurement method.

A precautionary measure to solve the problem] The method for measuring the straightness of a positioning table according to the present invention uses a reference block that has a non-negligible straightness error to measure the straightness error of the positioning table that is the measurement target. Even in cases where this is unavoidable, the true straightness of the positioning table, which eliminates the influence of the reference block, can be obtained through careful measurement methods and computer processing. As a means of doing so, when measuring the straightness of the positioning table with respect to the reference boots 5 placed on the table 1 shown in Fig. 1, the measurement reference point is set at the first time as shown in Fig. 5. In the measurement, the standard professional taste is 5 out of 0.
From any point DI on the surface, D! at the required measurement angle.・・・
・・・・・・・・・2n points of D victory, Den (outside is 2
1 over the required length t.
Measure the straightness of the positioning table.

Next, the reference block 5 is reversed by 180 degrees as shown in FIG. 5) and replaced so that the A end and B end are interchanged. At this time, it is noted that the reference point of the reference boot stock 5 is OrM and remains unchanged. Once the above replacement 6Z is completed,
It is the second measurement, but in one measurement, the D of the first measurement is
! t from the same point as point U, that is, from the end of the reference block 50B.
Point 11 (4 m, see Figure 4 for the dimension of q) at a distance of q from table 1, and measure It, It...
・? an-s, 1! :tn and 2n points on the reference block to measure the straightness of the positioning table. Next, for the first measurement (see fourth review), the reference block 5 on the table 1 is moved one pitch, that is, to the right, and placed at the 9th position. This t change b
When Z is completed, k is shown in IIEJ diagram (c) IC, but from this state, IFs, Pt...-IFtn-t
, IFtn-t, performs the third straightness measurement of the 1-positioning table using 2n-1 points as a reference skin.

Note that an air micrometer is used for all of the three measurements mentioned above. When the t6%-2 measured values thus obtained were processed by the computer 7 (see Figure 91) according to an appropriate algorithm, the straightness error of the reference block was reduced to a medium value. True positioning table straightness is obtained.

[Effect]

According to the above measurement method, Ds, D, etc. are measured in the first straightness measurement as shown in Fig. 5 et al.
・Di −tDz, Dz4t・・・・・・・・・・
DzH-s, the measured value for the D electric point is yl, respectively.
, y*......yi-x, yi, yi+s
, -ytn-s.

ytn and Ws Ik measured in the second straightness measurement as shown in ) in Figure 5...1! ! <-t
, Wi, Wi+s,・・・・・・・・・1z
nt, the measured value for point n is Zt,
Zt・・・・・Zi−*, Zi, Zi+s・
−=−Zzn−*, Zzn. Also, δi,
aj (tl, j=1.2・'-” 2s-1,2n
) Let u be the true straightness error of the positioning table, and Δ
V・, Δzz (<, jxl, 2. ・・・・・・2
n −1,2s ) is the straightness error of the reference deviation. Here, as shown in Figure 5(a) and (6),
δ, w%n=Q, Δ1/l=Δytn=O
.

Δ2. =Δ% n-Q From each value, from the first measurement.

't=''Ytnl-us)μ)x(<-1)le+1°From the second measurement value.

Q j= ((Zt n −Zt n ) ×(j−'
)n+Z.

When subtracting each, the result is 7/< −
g = δi −Δyi C4= 1, 2, −・−2s
) - (1) zj - ri = 9 - ΔZj (j = 1.2...
...2s)-(2) By the way, Ri and)n+1i are
As explained earlier, the points are the same.

Δyi=ΔZrn phantom-i (i=1.2...2
s)-(3) From formulas (1) to (3), n independent,
δs(sn1.2...2s)F-obtains a simultaneous equation with an unknown quantity.

δi −bh−i =yi −zms−i −pi +
qp-h-4ci = 1.2m2%) (4) Next, conduct m current for the third straightness measurement]lFtelFg
......F*n-*, Fm- as %s, threat...tcm-t, uznl
and is shown as Ic in FIG. 5(e). In the same figure, δl
;0. δ! Straight line B with n=0, and.

If a straight line M with Δul=O and Δstn=O is obtained.

δ +r, Δuk, sk Ckml, 2...
・= 2s-1) by combining the linear square equation s- with equation (4) to obtain all δ1 (i=1.2...
...2s) Any straight line S without information about h(, δ1 and tn)C that can be solved for IC
and +1 to δ, assuming T! /c versus δ”,
ΔKk for Δ'gk (k = 1, 2−...−
2s-1> + Otori book Assuming s'lLt@1g! Let n-1 be the dimension shown in FIG. 5(c).

Rk = ((u”, -, -5-vCl-h))X(
Ac-1) Ru + ÷ - (5) Using formula (9) *% -Rk z ak+, -61% (k xx 1
, 2...-2fL-1)-H6) If δ has +s
, "When the assumption of k is correct, δ Todoroki = Hongyo δ + 8. Δgk δi
+1 (t= 1.2+++++271-1)□(
7) Here, by substituting i=n into equations (4) and (7).

If we assume that (δn−δn+,) are equal.

Rn Qn −Zn+ sn−m−(8) From formula (8), Rn(ul, 5tn−t >wk(k N constant)
゛So, Kudzu! n-1 is expressed as a function of 1&. Therefore, arbitrarily determine the attack and *, and determine Rk by 5m (5).

As k-xi, substitute equation (71K, equation (7) and equation (4)
Choose an appropriate one out of a total of 35-2 -order square equations, solve it, substitute the solution into the remaining n-2 square equations, and solve it at once as long as there is no problem in terms of accuracy. If the solution converges to the following, take J< (4=1.2...2s) as the scale. Note that if the solution does not converge, it is because the assumption of U was incorrect, so it is corrected to improve accuracy.

The straightness data obtained through the steps described above is graphed as shown in FIG. 6, and the straightness is determined by the minimum area method, but this value does not include any influence of the reference block.

〔Example〕

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

The table 1 moves in the X direction according to the guide part 2 by the driving motor 3 and the power transmission screw 4.The straightness of the positioning table Ill: A reference block 5 with a slight straightness error is placed on the table 1, and the air Measure with a micrometer. An air microphone-meter was chosen as the measuring instrument because it is inexpensive but highly accurate, and because it is relatively insensitive to factors such as the surface roughness of the measurement ii (reference surface of the standard block). by. In the figure, the air microphone-meter detection section 8. Control unit 9. From an air micrometer,
The system is configured by a communication line 10 for automatically receiving the 8I constant value upon receiving a command from the combination machine 7. Further, a motor driver 1 unique to the system is connected to the drive unit 3 unique to the 1st position quantity determining table, and the motor driver 1 is driven according to instructions from the computer 7.

By driving the drive motor 3, the measurement is performed automatically. The separation of the reference block 5 due to the three-time change in the measurement pattern is carried out by humans (
It's a friend, and I'm aiming for automation in the future). Combi Tame-Evening 7th,
In addition to the tth system control of automatic measurement, the above calculation is performed. In this calculation, the number of measurement points is 2% (must be an even number), and the Gaussian simultaneous-order formula of 40 elements, which is appropriately selected from Equation 1 (4) and Equation 1 (7), with 5 = 20, is used. If you solve it by the process of elimination, it will be 16 bits, even on a personal computer.

It takes 60 seconds, and furthermore, it takes an enormous amount of time to correct xl and obtain a solution with sufficient accuracy. However, in the example, equation 1 (7) is δi−δ7++
By noting that it has the form = k'6 (Kli is a constant) and adding the sides.

δ1−δ2n=One in Mi! = (9) and compared it with Equation 1 (4) where j = 1 was set, and after setting a rough guide, we found a precise solution, so we could obtain the result within a time that is sufficiently useful for practical use. Can be a friend.

〔Effect of the invention〕

According to the present invention as described above, in the conventional measurement method using a reference boot, the straightness including the straightness error of the same proof is obtained as a measurement result. bt exists, but this limit is dramatically improved. In other words, since the straightness measurement method of this positioning table has a structural function to cancel the straightness error of the reference book, it is easy to do so by increasing the calculation accuracy of the combination table. ), the final result bζ is highly accurate to the point where it almost depends on the accuracy of the measuring instrument (such as an air micrometer). As an extension of the simple straightness measurement method using a reference block that has been conventionally carried out, the method of the present invention allows for general straightness measurement excluding some special measurement objects. Sufficient accuracy can be provided over a wide measurement range at low cost.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram of a positioning table straightness measurement system. FIG. 2 is an explanatory diagram of a conventional straightness measuring method. FIG. 3 is a diagram showing the relationship between table movement amount (3) and displacement in the Y direction. FIG. 4 shows the three patterns of measurement settings and measurement locations that are characteristic of the present invention, and FIG. 4 61 is a diagram showing the seven-point setting and measurement locations used to measure the straightness of the first change. ) in FIG. 4 is a diagram showing seriting and measurement points in the second straightness measurement. FIG. 4(C) is a diagram showing the settings and measurement locations for the third straightness measurement. Figure 5 is an auxiliary diagram for deriving the basic formula that supports the present invention.
is an explanatory diagram of the second straightness measurement. FIG. 5(c) is an explanatory diagram of the contents of the third straightness measurement. FIG. 6 is a diagram showing the final straightness. 1... Movable table 2... Guide section 3... Drive motor 4... Power transmission screw 5... Reference block 6. ... Displacement meter 7 ... Computer 8 ... Air micrometer detection section 9 ...
・Air micrometer control unit 10... Confucian wire 11... Fist motor driver and above

Claims (1)

[Claims] When measuring the straightness of a positioning table using a reference block with a non-ignorable error in straightness,
For the first measurement, measure from the arbitrary start point to the end point of the reference block, and for the second measurement, swap the left and right sides of the reference block and move from the end point of the first measurement to the start point, on the reference block. For the third measurement, the reference block is shifted to the right by one measurement point, and the three sets of measurement data obtained are calculated by computer. A method for measuring the straightness of a positioning table that does not include the straightness error of the reference block.