CN101913103A - Method for measuring angular errors of rotating table of numerical control machine - Google Patents

Abstract

The invention relates to a method for measuring the angular errors of a rotating table of a numerical control machine, which comprises the following steps of: firstly, determining the angular errors of the numerical control rotating table rotating around X axis and Y axis; using a high-precision standard ball as a measuring basis, determining the actual motion trail of the numerical control rotating table according to the special position of the measuring standard ball, and calculating the angular errors of the numerical control rotating table rotating around the X axis and the Y axis, wherein the standard ball is supported by a base bracket and fixed on the rotating table. In the invention, the standard ball and an infrared three-dimensional workpiece measuring head are used for forming a measuring system, the position of circle center and the angular errors of the numerical control rotating table are calculated by detecting the motion position of the standard ball, thereby providing a basis for compensating the annular errors of the rotating table.

Description

Method for measuring angular errors of rotating table of numerical control machine

Technical field

The present invention relates to a kind of angular errors of rotating table of numerical control machine detection method, especially a kind of five-axis linkage machine tools method for measuring angular errors of rotating table of numerical control machine that is used for.

Background technology

Rotating table of numerical control machine is the critical component that is applied to five-axis linkage machine tools, the positional precision of rotary table gyration is the key influence factor of decision location of workpiece benchmark, motion benchmark, therefore the angular errors of rotating table of numerical control machine detection technique is most important to the assurance of machine finish, is the key technology that high precision machine tool must solve.At present, also there is not a kind of angular errors of rotating table of numerical control machine accurate measurement method.

Summary of the invention

The present invention will provide a kind of method for measuring angular errors of rotating table of numerical control machine, this method utilizes standard ball and infrared three-dimension workpiece probe to form measuring system, detection according to the standard ball movement position, anti-NC rotary table home position and the angular errors obtained is for the compensation of the angular errors of rotary table provides foundation.

For achieving the above object, technical scheme of the present invention is: a kind of method for measuring angular errors of rotating table of numerical control machine comprises the steps:

1. the definition NC rotary table is around the angular errors of X-axis and Z axle

δ _X(θ _i)＝θ _i-θ _i′ (1)

δ _Z(θ _j)＝θ _j-θ _j′ (2)

θ in the formula _i, θ _jBe respectively actual measurement corner value, θ around X-axis and the rotation of Z axle _i', θ _j' be respectively nominal corner value around the rotation of X-axis and Z axle;

2. measure and obtain the angular errors of NC rotary table around X-axis and Z axle

With the high precision standard ball as measuring basis, standard ball is supported by base bracket, be fixed on the workbench, determine the actual motion track of NC rotary table, obtain the angular errors of NC rotary table around X-axis and Z axle by the locus of measurement standard ball.

Concrete measuring method a: standard ball is fixed on the workbench by base, control NC rotary table transposition drive motors and corner drive motors respectively, make NC rotary table center on the gyration that X-axis and Z axle are done two-freedom respectively, and the infrared three-dimension workpiece probe is installed on the main shaft of numerical control machine tool, in order to the centre of sphere movement locus position coordinates of measurement standard ball, and obtain the angular errors of NC rotary table.

NC rotary table is around the error measure of Z Shaft angle:

The transposition servomotor is fixed on NC rotary table apart from a certain angle position φ of horizontal plane, controls the corner drive motors then and drives NC rotary table around the rotation of Z axle, makes it rotate ψ respectively ₁, ψ ₂..., ψ _nAngle, and measure the centre of sphere space coordinates (X of standard ball on the NC rotary table _{ψ 1}, Y _{ψ 1}, Z _{ψ 1}), (X _{ψ 2}, Y _{ψ 2}, Z _{ψ 2}) ..., (X _{ψ n}, Y _{ψ n}, Z _{ψ n}).Calculate the corner of NC rotary table for convenience,, calculate NC rotary table, rotate to the plan-position of φ=0 ° at it around X-axis-φ angle by coordinate transformation method, definition coordinate system X ' OY ', and with the centre of sphere space coordinates (X of standard ball _{ψ 1}, Y _{ψ 1}, Z _{ψ 1}), (X _{ψ 2}, Y _{ψ 2}, Z _{ψ 2}) ..., (X _{ψ n}, Y _{ψ n}, Z _{ψ n}) be transformed into the coordinate (X on coordinate system X ' OY ' _{ψ 1}', Y _{ψ 1}', Z _{ψ 1}'), (X _{ψ 2}', Y _{ψ 2}', Z _{ψ 2}') ...,, (X _{ψ n}', Y _{ψ n}', Z _{ψ n}').Wherein

X _ψi′＝X _ψi (3)

Y _ψi′＝Y _ψicosφ-Z _ψisinφ (4)

Z _ψi′＝Y _ψisinφ+Z _ψicosφ (5)

I=1 in the formula, 2 ..., n, through type (3)-Shi (5) is converted to X ' OY ' with the sphere center position coordinate of standard ball by coordinate system XOY; Standard ball centre of sphere point (X _{ψ i}', Y _{ψ i}', Z _{ψ i}') and point (X _{ψ j}', Y _{ψ j}', Z _{ψ j}') between around the rotational angle theta of Z axle _IjTry to achieve by formula (6):

$\sin {\mathrm{\θ}}_{\mathrm{ij}}=\frac{{Y_{\mathrm{\ψj}}}^{\′}-{Y_{\mathrm{\ψi}}}^{\′}}{R}---\left(6\right)$

R in the formula is the distance of the centre of sphere apart from rotary table axis of rotation Z axle, and the equation of a circle of standard ball centre of sphere track is expressed as:

(X′-X ₀′) ²+(Y′-Y ₀′) ²＝R ² (7)

Coordinate figure (X with three centre ofs sphere _{ψ i}', Y _{ψ i}'), (X _{ψ j}', Y _{ψ j}'), (X _{ψ k}', Y _{ψ k}') substitution formula (7), obtain the central coordinate of circle (X of centre of sphere track ₀', Y ₀') and the centre of sphere apart from the distance R of the axis of rotation of rotary table, with R substitution formula (6), try to achieve point (X _{ψ i}', Y _{ψ i}', Z _{ψ i}') and point (X _{ψ j}', Y _{ψ j}', Z _{ψ j}') between rotational angle theta _Ij, according to the nominal value θ of this angle _Ij' and calculate angular errors δ by formula (1) _Z(θ _Ij).In like manner, obtain the angular errors of other position.

NC rotary table is around the measurement of X-axis angular errors:

If when NC rotary table is measured angular errors around X-axis,, make it rotate φ respectively at the slewing area inner control transposition drive motors of NC rotary table around X-axis ₁, φ ₂..., φ _mAngle, and measure the centre of sphere space coordinates (X of standard ball on the NC rotary table _{φ 1}, Y _{φ 1}, Z _{φ 1}), (X _{φ 2}, Y _{φ 2}, Z _{φ 2}) ..., (X _{φ m}, Y _{φ m}, Z _{φ m}), basis of calculation ball centre of sphere space coordinates (X _{φ 1}, Y _{φ 1}, Z _{φ 1}), (X _{φ 2}, Y _{φ 2}, Z _{φ 2}) ..., (X _{φ m}, Y _{φ m}, Z _{φ m}) coordinate figure that is projected to the YOZ plane is: (O, Y _{φ 1}, Z _{φ 1}), (O, Y _{φ 2}, Z _{φ 2}) ...,, (O, Y _{φ m}, Z _{φ m}); Obtain standard ball centre of sphere space coordinates (O, Y on the NC rotary table by formula (8) _{φ i}, Z _{φ i}) and (O, Y _{φ j}, Z _{φ j}) between included angle _Ij

${\cos \mathrm{\φ}}_{\mathrm{ij}}=\frac{b^2+c^2-a^2}{2\mathrm{bc}}---\left(8\right)$

Wherein, NC rotary table is swung geometrical relationship around X-axis:

$a=\sqrt{{(Y_{\mathrm{\φi}}-Y_{\mathrm{\φj}})}^2+{(Z_{\mathrm{\φi}}-Z_{\mathrm{\φj}})}^2}$

$b=\sqrt{{Y_{\mathrm{\φi}}}^2+{Z_{\mathrm{\φi}}}^2}---\left(9\right)$

$c=\sqrt{{Y_{\mathrm{\φj}}}^2+{Z_{\mathrm{\φj}}}^2}$

According to formula (8) and formula (9),, try to achieve the rotational angle φ of NC rotary table around X-axis by the centre of sphere spatial value of standard ball on the NC rotary table _Ij, and according to the nominal value φ of this angle _Ij' and calculate angular errors δ by formula (1) _X(φ _Ij).

The invention has the beneficial effects as follows: rotating table of numerical control machine is the critical component that is applied to five-axis linkage machine tools, the positional precision of rotary table gyration is the key influence factor of decision location of workpiece benchmark, motion benchmark, therefore the angular errors of rotating table of numerical control machine detection technique is most important to the assurance of machine finish, is the key technology that high precision machine tool must solve.The present invention utilizes standard ball and infrared three-dimension workpiece probe to form measuring system, and according to the detection of standard ball movement position, anti-NC rotary table home position and the angular errors obtained is for the angular errors compensation of rotary table provides foundation.

Description of drawings

Fig. 1 is the fundamental diagram of two-freedom NC rotary table;

Fig. 2 is the standard ball position view;

Fig. 3 is that standard ball is measured the track schematic diagram;

Fig. 4 is a standard ball initial position schematic diagram;

Fig. 5 is that NC rotary table is around X-axis swing geometrical relationship schematic diagram.

The specific embodiment

The present invention is further illustrated below in conjunction with accompanying drawing and embodiment.

1. method for measuring angular errors of rotating table of numerical control machine

The schematic diagram of two-freedom NC rotary table as shown in Figure 1.According to the needs of workpiece processing, NC rotary table is driven by transposition drive motors and corner drive motors, centers on the gyration that X-axis and Z axle are done two-freedom respectively.And the angular errors of NC rotary table is the important indicator of rotary table system performance, is also directly determining the machining accuracy of numerical control machining center.NC rotary table is defined as respectively around the angular errors of X-axis and Z axle:

δ _X(θ _i)＝θ _i-θ _i′ (1)

δ _Z(θ _j)＝θ _j-θ _j′ (2)

θ in the formula _i, θ _jBe respectively actual measurement corner value, θ around X-axis and the rotation of Z axle _i', θ _j' be respectively nominal corner value around the rotation of X-axis and Z axle.

In order to measure the angular errors of NC rotary table, the present invention adopts the high precision standard ball as measuring basis, standard ball is supported by base bracket, be fixed on the workbench, determine the actual motion track of NC rotary table by the locus of measurement standard ball, obtain the angular errors of NC rotary table with the method.

Concrete measurement scheme is as follows: a standard ball is fixed on the workbench, by base as shown in Figure 2.Control NC rotary table transposition drive motors and corner drive motors respectively, make NC rotary table center on the gyration that X-axis and Z axle are done two-freedom respectively.And the infrared three-dimension workpiece probe is installed on the main shaft of numerical control machine tool, in order to the centre of sphere movement locus position coordinates of measurement standard ball, and obtain the angular errors of NC rotary table.Below narrate NC rotary table respectively around Z Shaft angle error and around the measuring method of X-axis angular errors.

2. NC rotary table is around the measuring method of Z Shaft angle error

The transposition servomotor is fixed on NC rotary table apart from a certain angle position φ of horizontal plane, controls the corner drive motors then and drives NC rotary table around the rotation of Z axle, as shown in Figure 3, makes it rotate ψ respectively ₁, ψ ₂..., ψ _nAngle, and measure the centre of sphere space coordinates (X of standard ball on the NC rotary table _{ψ 1}, Y _{ψ 1}, Z _{ψ 1}), (X _{ψ 2}, Y _{ψ 2}, Z _{ψ 2}) ..., (X _{ψ n}, Y _{ψ n}, Z _{ψ n}).Calculate the corner of NC rotary table for convenience,, calculate NC rotary table, rotate to the plan-position of φ=0 ° at it around X-axis-φ angle by coordinate transformation method, definition coordinate system X ' OY ', and with the centre of sphere space coordinates (X of standard ball _{ψ 1}, Y _{ψ 1}, Z _{ψ 1}), (X _{ψ 2}, Y _{ψ 2}, Z _{ψ 2}) ..., (X _{ψ n}, Y _{ψ n}, Z _{ψ n}) be transformed into the coordinate (X on coordinate system X ' OY ' _{ψ 1}', Y _{ψ 1}', Z _{ψ 1}'), (X _{ψ 2}', Y _{ψ 2}', Z _{ψ 2}') ...,, (X _{ψ n}', Y _{ψ n}', Z _{ψ n}').Wherein

X _ψi′＝X _ψi (3)

Y _ψi′＝Y _ψicosφ-Z _ψisinφ (4)

Z _ψi′＝Y _ψisinφ+Z _ψicosφ (5)

I=1 in the formula, 2 ..., n.Through type (3)-Shi (5) can be converted to X ' OY ' by coordinate system XOY with the sphere center position coordinate of standard ball.

Standard ball centre of sphere point (X _{ψ i}', Y _{ψ i}', Z _{ψ i}') and point (X _{ψ j}', Y _{ψ j}', Z _{ψ j}') between around the rotational angle theta of Z axle _IjCan try to achieve by following formula:

$\sin {\mathrm{\θ}}_{\mathrm{ij}}=\frac{{Y_{\mathrm{\ψj}}}^{\′}-{Y_{\mathrm{\ψi}}}^{\′}}{R}---\left(6\right)$

R in the formula is the distance of the centre of sphere apart from rotary table axis of rotation Z axle, and its value can be tried to achieve by the coordinate figure of three centre ofs sphere.The equation of a circle of standard ball centre of sphere track can be expressed as:

(X′-X ₀′) ²+(Y′-Y ₀′) ²＝R ² (7)

(X in the formula ₀', Y ₀') be the central coordinate of circle of centre of sphere track.Coordinate figure (X with three centre ofs sphere _{ψ i}', Y _{ψ i}'), (X _{ψ j}', Y _{ψ j}'), (X _{ψ k}', Y _{ψ k}') substitution formula (7), can obtain the central coordinate of circle (X of centre of sphere track ₀', Y ₀') and the centre of sphere apart from the distance R of the axis of rotation of rotary table, with R substitution formula (6), can try to achieve point (X _{ψ i}', Y _{ψ i}', Z _{ψ i}') and point (X _{ψ j}', Y _{ψ j}', Z _{ψ j}') between rotational angle theta _Ij, according to the nominal value θ of this angle _Ij' and calculate angular errors δ by formula (1) _Z(θ _Ij).In like manner, can obtain the angular errors of other position.

3. NC rotary table is around the measuring method of X-axis angular errors

When if NC rotary table is measured angular errors around X-axis, the position A of standard ball as shown in Figure 4, NC rotary table has certain scope around the rotation (swing) of X-axis, at its scope inner control transposition drive motors, makes it rotate φ respectively ₁, φ ₂..., φ _mAngle, and measure the centre of sphere space coordinates (X of standard ball on the NC rotary table _{φ 1}, Y _{φ 1}, Z _{φ 1}), (X _{φ 2}, Y _{φ 2}, Z _{φ 2}) ..., (X _{φ m}, Y _{φ m}, Z _{φ m}).Calculate the corner of NC rotary table for convenience, basis of calculation ball centre of sphere space coordinates (X around X-axis _{φ 1}, Y _{φ 1}, Z _{φ 1}), (X _{φ 2}, Y _{φ 2}, Z _{φ 2}) ..., (X _{φ m}, Y _{φ m}, Z _{φ m}) coordinate figure that is projected to the YOZ plane is: (O, Y _{φ 1}, Z _{φ 1}), (O, Y _{φ 2}, Z _{φ 2}) ...,, (O, Y _{φ m}, Z _{φ m}).

Fig. 5 illustrates NC rotary table around X-axis swing geometrical relationship schematic diagram, according to the diagram geometrical relationship, can obtain standard ball centre of sphere space coordinates (O, Y on the NC rotary table _{φ i}, Z _{φ i}) and (O, Y _{φ j}, Z _{φ j}) between included angle _IjComputing formula:

${\cos \mathrm{\φ}}_{\mathrm{ij}}=\frac{b^2+c^2-a^2}{2\mathrm{bc}}---\left(8\right)$

Wherein, NC rotary table is swung geometrical relationship around X-axis:

$a=\sqrt{{(Y_{\mathrm{\φi}}-Y_{\mathrm{\φj}})}^2+{(Z_{\mathrm{\φi}}-Z_{\mathrm{\φj}})}^2}$

$b=\sqrt{{Y_{\mathrm{\φi}}}^2+{Z_{\mathrm{\φi}}}^2}---\left(9\right)$

$c=\sqrt{{Y_{\mathrm{\φj}}}^2+{Z_{\mathrm{\φj}}}^2}$

According to formula (8) and formula (9),, can try to achieve the rotational angle φ of NC rotary table around X-axis by the centre of sphere spatial value of standard ball on the NC rotary table _Ij, and according to the nominal value φ of this angle _Ij' and calculate angular errors δ by formula (1) _X(φ _Ij).

Claims (4)

1. method for measuring angular errors of rotating table of numerical control machine is characterized in that:

(1) the definition NC rotary table is around the angular errors of X-axis and Z axle

δ _X(θ _i)＝θ _i-θ _i′ (1)

δ _Z(θ _j)＝θ _j-θ _j′ (2)

θ in the formula _i, θ _jBe respectively actual measurement corner value, θ around X-axis and the rotation of Z axle _i', θ _j' be respectively nominal corner value around the rotation of X-axis and Z axle;

(2) measure and obtain the angular errors of NC rotary table around X-axis and Z axle

With the high precision standard ball as measuring basis, standard ball is supported by base bracket, be fixed on the workbench, determine the actual motion track of NC rotary table, obtain the angular errors of NC rotary table around X-axis and Z axle by the locus of measurement standard ball.

2. method for measuring angular errors of rotating table of numerical control machine according to claim 1, it is characterized in that: described measurement and obtain NC rotary table and be: a standard ball is fixed on the workbench by base around the concrete measuring method of angular errors of X-axis and Z axle, control NC rotary table transposition drive motors and corner drive motors respectively, make NC rotary table center on the gyration that X-axis and Z axle are done two-freedom respectively, and the infrared three-dimension workpiece probe is installed on the main shaft of numerical control machine tool, in order to the centre of sphere movement locus position coordinates of measurement standard ball, and obtain the angular errors of NC rotary table.

3. method for measuring angular errors of rotating table of numerical control machine according to claim 1 is characterized in that: described NC rotary table around the concrete measuring method of Z Shaft angle error is:

The transposition servomotor is fixed on NC rotary table apart from a certain angle position φ of horizontal plane, controls the corner drive motors then and drives NC rotary table around the rotation of Z axle, makes it rotate ψ respectively ₁, ψ ₂..., ψ _nAngle, and measure the centre of sphere space coordinates (X of standard ball on the NC rotary table _{ψ 1}, Y _{ψ 1}, Z _{ψ 1}), (X _{ψ 2}, Y _{ψ 2}, Z _{ψ 2}) ..., (X _{ψ n}, Y _{ψ n}, Z _{ψ n}).Calculate the corner of NC rotary table for convenience,, calculate NC rotary table, rotate to the plan-position of φ=0 ° at it around X-axis-φ angle by coordinate transformation method, definition coordinate system X ' OY ', and with the centre of sphere space coordinates (X of standard ball _{ψ 1}, Y _{ψ 1}, Z _{ψ 1}), (X _{ψ 2}, Y _{ψ 2}, Z _{ψ 2}) ..., (X _{ψ n}, Y _{ψ n}, Z _{ψ n}) be transformed into the coordinate (X on coordinate system X ' OY ' _{ψ 1}', Y _{ψ 1}', Z _{ψ 1}'), (X _{ψ 2}', Y _{ψ 2}', Z _{ψ 2}') ...,, (X _{ψ n}', Y _{ψ n}', Z _{ψ n}').Wherein

X _ψi′＝X _ψi (3)

Y _ψi′＝Y _ψicosφ-Z _ψisinφ (4)

Z _ψi′＝Y _ψisinφ+Z _ψicosφ (5)

I=1 in the formula, 2 ..., n, through type (3)-Shi (5) is converted to X ' OY ' with the sphere center position coordinate of standard ball by coordinate system XOY; Standard ball centre of sphere point (X _{ψ i}', Y _{ψ i}', Z _{ψ i}') and point (X _{ψ j}', Y _{ψ j}', Z _{ψ j}') between around the rotational angle theta of Z axle _IjTry to achieve by formula (6):

$\sin {\mathrm{\θ}}_{\mathrm{ij}}=\frac{{Y_{\mathrm{\ψj}}}^{\′}-{Y_{\mathrm{\ψi}}}^{\′}}{R}---\left(6\right)$

R in the formula is the distance of the centre of sphere apart from rotary table axis of rotation Z axle, and the equation of a circle of standard ball centre of sphere track is expressed as:

(X′-X ₀′) ²+(Y′-Y ₀′) ²＝R ² (7)

Coordinate figure (X with three centre ofs sphere _{ψ i}', Y _{ψ i}'), (X _{ψ j}', Y _{ψ j}'), (X _{ψ k}', Y _{ψ k}') substitution formula (7), obtain the central coordinate of circle (X of centre of sphere track ₀', Y ₀') and the centre of sphere apart from the distance R of the axis of rotation of rotary table, with R substitution formula (6), try to achieve point (X _{ψ i}', Y _{ψ i}', Z _{ψ i}') and point (X _{ψ j}', Y _{ψ j}', Z _{ψ j}') between rotational angle theta _Ij, according to the nominal value θ of this angle _Ij' and calculate angular errors δ by formula (1) _Z(θ _Ij); In like manner, obtain the angular errors of other position.

4. method for measuring angular errors of rotating table of numerical control machine according to claim 1 is characterized in that: described NC rotary table around the concrete measuring method of X-axis angular errors is:

If when NC rotary table is measured angular errors around X-axis,, make it rotate φ respectively at the slewing area inner control transposition drive motors of NC rotary table around X-axis ₁, φ ₂..., φ _mAngle, and measure the centre of sphere space coordinates (X of standard ball on the NC rotary table _{φ 1}, Y _{φ 1}, Z _{φ 1}), (X _{φ 2}, Y _{φ 2}, Z _{φ 2}) ..., (X _{φ m}, Y _{φ m}, Z _{φ m}), basis of calculation ball centre of sphere space coordinates (X _{φ 1}, Y _{φ 1}, Z _{φ 1}), (X _{φ 2}, Y _{φ 2}, Z _{φ 2}) ..., (X _{φ m}, Y _{φ m}, Z _{φ m}) coordinate figure that is projected to the YOZ plane is: (O, Y _{φ 1}, Z _{φ 1}), (O, Y _{φ 2}, Z _{φ 2}) ...,, (O, Y _{φ m}, Z _{φ m}); Obtain standard ball centre of sphere space coordinates (O, Y on the NC rotary table by formula (8) _{φ i}, Z _{φ i}) and (O, Y _{φ j}, Z _{φ j}) between included angle _Ij

${\cos \mathrm{\φ}}_{\mathrm{ij}}=\frac{b^2+c^2-a^2}{2\mathrm{bc}}---\left(8\right)$

Wherein, NC rotary table is swung geometrical relationship around X-axis:

$a=\sqrt{{(Y_{\mathrm{\φi}}-Y_{\mathrm{\φj}})}^2+{(Z_{\mathrm{\φi}}-Z_{\mathrm{\φj}})}^2}$

$b=\sqrt{{Y_{\mathrm{\φi}}}^2+{Z_{\mathrm{\φi}}}^2}---\left(9\right)$

$c=\sqrt{{Y_{\mathrm{\φj}}}^2+{Z_{\mathrm{\φj}}}^2}$

According to formula (8) and formula (9),, try to achieve the rotational angle φ of NC rotary table around X-axis by the centre of sphere spatial value of standard ball on the NC rotary table _Ij, and according to the nominal value φ of this angle _Ij' and calculate angular errors δ by formula (1) _X(φ _Ij).

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