JPH079303A - Machine parameter correcting method and device of machine tool - Google Patents

Abstract

PURPOSE:To provide the correcting method and the correcting device of the machine parameter of a machine tool which can lead out the absolute value of the machine parameter intently. CONSTITUTION:While a grinding wheel is made in a V-shaped grinding wheel having plural processing surfaces, plural first form generating surface data Dmi obtained by converting the input NC data Dsi by using a form generating model M is taken in a memory, and the first reference point Pr1 to correct the machine parameter q included in the first generating model M depending on the plural first form generating surface data Dmi is operated. And the actual grinding process surface of a work by the V-shaped grinding wheel is processed three-dimensionally to obtain plural second form generating data Ddi, the second reference point Pr2 to correct the machine parameter q included in the form generating model M depending on the plural second form generating surface data Ddi is operated, and the system is composed to correct the machine parameter q by comparing the first and the second reference points Pr1 and Pr2. Consequently, the absolute value of the machine parameter can be led out intently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting machine parameters of a machine tool and an apparatus therefor, and more specifically, it processes a workpiece with a machining tool attached to the tip of a mechanism such as a program-controlled link mechanism. The present invention relates to a method and apparatus for correcting machine parameters of a machine tool that corrects machine parameters that determine the operating characteristics of a machine tool that performs shape generation.

[0002]

2. Description of the Related Art Conventionally, NC machine tools have been machine-difference compensated by using a standard machining tool such as an end mill or a grindstone attached to the tip of a link mechanism to machine a workpiece into, for example, a cylindrical shape. This was done by evaluating the difference between the target shape and the target shape. This machined shape is, in other words, an envelope figure of a machining point or machining line of a machining tool. Then, when it is evaluated that the machine difference correction is necessary, it is necessary to correct the machine parameter such as the offset amount and the rotation speed of the NC machine tool. It was done by direct measurement. However, since there are many machine parameters to be corrected, it takes a long time to measure them, and there are machine parameters that are difficult to measure directly (for example, tilting of the axis), and further there are problems that individual differences easily occur. Therefore, the present inventors have developed the following correction method (Japanese Patent Application No. 04-0
No. 31665). FIG. 10 is an explanatory diagram showing a schematic flow in an example of such a conventional method of correcting machine parameters of a machine tool, and FIG. 11 is an explanatory diagram showing a relationship between a trajectory of a conventional machining tool and an envelope surface. As shown in FIG. 10, according to the conventional correction method, a coordinate conversion calculation (modeled from the locus of the machining tool to the above machining from the locus of the machining tool) in which the machining target shape of the workpiece 3 to be ground by the grindstone 2 is modeled including the machine parameter q of the NC grinder 1 The shape generation model M (for conversion to the target shape) is input (S1), and the NC data D _si which is the operating characteristic data (that is, the trajectory data of the machining tool) of the coordinate system of the NC grinder 1 is input (S2). , The NC data D _si using the above-mentioned shape generation model M is _converted into the first shape generation surface data D _mi of the coordinate system of the work 3.
(S3), while NC based on the NC data D _si
The work 3 is actually ground by driving the grinder 1 (S
4), work 3 from the shape generation surface obtained by this actual grinding
The second shape creation surface data D _di in the coordinate system of 3D is three-dimensionally measured (S5), and the first shape creation surface data D _mi obtained by coordinate conversion in step S3 and the second shape creation surface data D _mi obtained in step S5.
The machine parameter q included in the shape generation model M is corrected by comparing the shape generation surface data D _{di of}
6) is configured. FIG. 11 shows this NC grinder 1.
The relationship between the locus of the cylindrical grindstone 2 which is a processing tool used for and its envelope surface is shown, and this envelope surface corresponds to the above-mentioned shape generating surface. As described above, by comparing the machining target shape data calculated using the shape generation model including the machine parameter of the machine tool with the actual machining shape data, all of the machine parameters could be corrected quickly and accurately. .

[0003]

In the conventional method for correcting machine parameters of a machine tool as described above, since the evaluation target is the machining shape (envelope shape), the machining shape is calculated from the measured machining shape information. The locus (position, posture) of the created tool at the tip of the link may not be uniquely determined. For example, a processing tool (cylindrical grindstone) as shown in FIG.
Even if the tool locus deviates in the direction parallel to the envelope surface, it is interpreted as the same plane with respect to. Therefore, the position information of the envelope surface could not be defined, and there was no guarantee that the corrected machine parameters would be uniquely determined. The present invention has been made to solve the above problems in the conventional technique, and an object thereof is a method for correcting machine parameters of a machine tool that can uniquely derive the absolute value of the machine parameter of the machine tool. And to provide the device.

[0004]

In order to achieve the above-mentioned object, the main means adopted by the present invention is the gist of the present invention, in which a workpiece is machined by a machining tool attached to the tip of a program-controlled mechanism. What is claimed is: 1. A method for correcting machine parameters of a machine tool, which corrects machine parameters for determining the operating characteristics of a machine tool for machining and creating a shape, comprising: a trajectory of the machining tool and an object to be machined machined by the machining tool. Input the shape generation model for coordinate transformation calculation that models the relationship with the processing target shape including the machine parameters, input the trajectory data of the processing tool, and use the shape generation model to convert the trajectory data to the above. It is converted into the first shape generation surface data of the coordinate system of the object to be machined, and the machine tool is driven based on the trajectory data to realize the object to be machined. The shape-creating surface obtained by machining is three-dimensionally measured to obtain second shape-creating surface data in the coordinate system of the object to be processed, and the first shape-creating surface data and the second shape-creating surface data are obtained. In a method for correcting machine parameters of a machine tool, which corrects the machine parameters included in the shape generation model based on
Of the above-mentioned shape generation surface data based on the plurality of first shape generation surface data, while making the processing tool with a plurality of processing surfaces to obtain the shape generation surface data of The first reference point for correcting the machine parameter included in the model is calculated, and the machine parameter included in the shape generating model is corrected based on the plurality of second shape generating surface data corresponding to the machining tool. A method for correcting a machine parameter of a machine tool, characterized in that the machine parameter is corrected by calculating a second reference point for performing the operation and comparing the first reference point with the second reference point. Is.

Further, a machine parameter compensating device for compensating machine parameters for determining operating characteristics of a machine tool for machining a machining target with a machining tool attached to the tip of a program-controlled mechanism. Which is a model for inputting a shape generation model for coordinate conversion calculation that models the relationship between the trajectory of the processing tool and the processing target shape of the processing target processed by the processing tool, including the machine parameters. Input means, data input means for inputting the trajectory data of the processing tool, and shape generation model input by the model input means are used to convert the trajectory data input by the data input means into the coordinate system of the workpiece. Based on the locus data input by the data inputting means, Measuring means for three-dimensionally measuring a shape-creating surface obtained by actually machining the object to be machined by driving a machine tool to obtain second shape-creating surface data in a coordinate system of the object to be machined; The first converted by the conversion means
Of the machine parameter of the machine tool, which comprises a correcting means for correcting the machine parameter included in the shape generating model based on the shape generating surface data of No. 1 and the second shape generating surface data measured by the measuring means. In the device, the processing tool is a processing tool having a plurality of processing surfaces for obtaining a plurality of second shape generation surface data, and
A memory for fetching a plurality of first shape-creating surface data converted by the transforming means, and a machine parameter included in the shape-creating model is corrected based on the plurality of first shape-creating surface data fetched in the memory. Included in the shape generation model based on the first calculation means for calculating a first reference point for the above and the plurality of second shape generation surface data corresponding to the machining tools measured by the measurement means. Second calculation means for calculating a second reference point for correcting a machine parameter is provided, and the first reference point calculated by the first calculation means and the second calculation means are calculated by the second calculation means. A device for correcting machine parameters of a machine tool, which corrects the machine parameters by comparing the second reference point with the correction means.

[0006]

According to the method and apparatus for correcting machine parameters of a machine tool of the present invention, the model of the relationship between the locus of the machining tool and the machining target shape of the machining object machined by the machining tool including the machine parameter. The shape generation model for the coordinate transformation calculation is input, the trajectory data of the machining tool is input, and the trajectory data is converted to the first shape generation surface data of the coordinate system of the workpiece by using the shape generation model. And the second shape of the coordinate system of the machining target by three-dimensionally measuring the shape generating surface obtained by actually machining the machining target by driving the machine tool based on the trajectory data. When the generation surface data is obtained and the machine parameter included in the shape generation model is corrected based on the first shape generation surface data and the second shape generation surface data, the addition is performed. The tool is made into a machining tool having a plurality of machining surfaces for obtaining a plurality of second shape-creating surface data, and a plurality of first shape-creating surface data are stored in a memory to obtain the plurality of first shapes. A first reference point for correcting a machine parameter included in the shape generation model is calculated based on the generation surface data, and the shape is calculated based on the plurality of second shape generation surface data corresponding to the machining tool. A second reference point for correcting the machine parameter included in the creation model is calculated, and the machine parameter is corrected by comparing the first reference point and the second reference point. Since both the first reference point and the second reference point are uniquely determined in the three-dimensional space, the corrected machine parameter can also be uniquely determined. As a result, it is possible to obtain a method and apparatus for correcting a machine parameter of a machine tool that can uniquely derive the absolute value of the machine parameter of the machine tool.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. In addition, the following embodiments are examples of embodying the present invention and are not accurate for limiting the technical scope of the present invention. 1 is an explanatory view showing a schematic flow of a method for correcting machine parameters of a machine tool according to an embodiment of the present invention, FIG. 2 is a block diagram showing a schematic configuration of a correction device A by the correction method, and FIG. Is an explanatory view showing a schematic shape of a V-shaped grindstone, FIG. 4 is an explanatory view showing a relationship between a trajectory of the V-shaped grindstone and an envelope cross section, FIG.
Is an explanatory view showing a wound forming shape with a V-shaped grindstone, FIG. 6 is an explanatory view showing a coordinate system of an NC machine tool, FIG. 7 is an explanatory view showing a coordinate system and machine parameters of a 5-axis NC grinder, and FIG. 8 is a test. FIG. 9 is an explanatory diagram showing a grinding state, and FIG. 9 is an explanatory diagram showing Euler angles. The same reference numerals are used for the elements common to the explanatory view showing the schematic flow in the example of the conventional method for correcting the machine parameters of the machine tool shown in FIG. As shown in FIG. 1, the method for correcting machine parameters of a machine tool according to the present embodiment uses a grindstone 2 (corresponding to a machining tool) attached to the tip of a program-controlled link mechanism to correspond to a work 3 (corresponding to a machining target). NC that processes the
A method for correcting a machine parameter q that determines the operating characteristics of a grinder 1 (corresponding to a machine tool), in which the relationship between the locus of the grindstone 2 and the machining target shape of the workpiece 3 machined by this grindstone 2 A shape generation model M for coordinate conversion calculation modeled including q is input (S1), and NC data D _si which is operation characteristic data of the coordinate system of the NC grinder 1.
(Corresponding to the trajectory data of the machining tool) is input (S2), the NC data D _si is converted into the first shape generation surface data D _mi of the coordinate system of the work 3 using the shape generation model M (S3),
The work 3 is processed by driving the NC grinder 1 based on the NC data D _si (S4), and the shape generation surface obtained by this processing is three-dimensionally measured to obtain the second shape of the coordinate system of the work 3. Conventionally, the generation surface data D _di is obtained (S5), and the machine parameter q included in the shape generation model M is corrected based on the first shape generation surface data D _mi and the second shape generation surface data D _di. Similar to the example. However, in this embodiment, the grindstone 2 has a plurality of processing surfaces for obtaining a plurality of second shape generation surface data D _di, and a plurality of the first shape generation surface data D _mi is stored in the memory. , The first reference point P _r1 for correcting the machine parameter q included in the shape generation model M is calculated based on the plurality of first shape generation surface data D _mi (S3 ′), and corresponds to the grindstone 2. That is, a plurality of grinding surfaces obtained by actual grinding with the grindstone 2 are actually detected, and the second shape creation surface data D _di obtained by the detection
The second reference point P _r2 for correcting the machine parameter q included in the shape generation model M is calculated based on (S
5 '), the machine parameter q is corrected by comparing the first reference point P _r1 and the second reference point P _r2 (S6').
Is configured.

In the correction device A based on this correction method, the step 1 in FIG.
(Corresponding to model input means), and then step S2 is performed by the data input circuit 6 (corresponding to data input means), step S3 is performed by the conversion circuit 7 (corresponding to conversion means), and step S4 is performed by the NC grinder 1. , Step S5
By the three-dimensional measuring machine 4 (corresponding to the measuring means), step S3 'by the memory 9 and the first arithmetic circuit 10 (corresponding to the first arithmetic means), and step S5' by the second arithmetic circuit 11 (the second arithmetic circuit). (Corresponding to the calculation means of 2), step S6 '
Are executed by the correction circuit 8 (corresponding to correction means) (see FIG. 2). The basic principle of this correction method and this apparatus will be described below. Here is a 5-axis NC grinder 1
For machine-difference correction, arm tip (grinding stone mounting axis)
A grindstone 2 (hereinafter referred to as a V-shaped grindstone) in which two truncated cone-shaped grindstones as shown in FIG. The symbol and name of this representative dimension are defined as follows.

[Equation 1] Next, as shown in FIG. 4, the shape of the V-shaped grindstone 2 that is created when the V-shaped grindstone 2 is tilted by an angle ψ with respect to the traveling direction and is moved linearly to perform grinding will be considered. The shape created by grinding is
It is an envelope figure of V type grindstone 2. An envelope figure is projected on an arbitrary section (hereinafter referred to as an envelope section) perpendicular to the traveling direction of the V-shaped grindstone 2, and a coordinate system as shown in the figure is set. That is, the coordinate system of this envelope cross section is: y-axis: perpendicular to the envelope cross section and passing through the center of the V-shaped grindstone 2. x-axis, z axis: passing through the center of the V-shaped grindstone 2 within the envelope cross-section. For simplification, the left virtual tip of the V-shaped grindstone 2 should be in the region of x <0 in the envelope cross section coordinate system, and the actual creation surface should be in the region of z ≦ 0 in the envelope cross section coordinate system. Define to. The origin of the envelope cross-section coordinate system is on the envelope cross-section.

In the figure, C ₁ , C ₂ and C ₃ are points on the left side, the right side and the center of the V-shaped grindstone 2, respectively, and are E ₁ , E ₂ and E _3.
Are ellipses obtained by projecting the points C ₁ , C ₂ and C ₃ on the envelope cross section. Also, in order to create the envelope cross section as shown in the figure,

[Equation 2]Is a necessary condition. Hereafter, wear on the part of z ≦ 0 of the envelope cross section.
To see. Intersection B of the x-axis in the figure₁Through the ellipse E₁, E₃
A straight line tangent to₁, Another intersection with the x-axis B₂Through
Ellipse E₂, E₃A straight line tangent to₂And Straight line l
₁And ellipse E₁, E₃Each contact of P₁Q₁, Straight line l
₂And ellipse E₂, E₃Each contact of P ₂, Q₂Defined as
It A figure obtained by projecting the envelope figure of the V-shaped grindstone 2 on the envelope section.
Is an ellipse E ₁, E₂, E₃And line segment P₁Q₁And P₂Q₂To
More enclosed. Therefore, on the envelope cross section (xz coordinate system)
At point B₁, B₂The position of can be expressed as follows.

[Equation 3] The major and minor axes of the ellipse E ₃ are 2R and 2Rsi, respectively.
n ψ. Due to the geometrical relationship, the formulas of the straight lines l ₁ and l ₂ that pass the points B ₁ and B ₂ and are in contact with the ellipse E ₃ are as follows.

[Equation 4] At this time, the angles λ ₁ and λ ₂ formed by the straight lines l ₁ and l ₂ and the x-axis
Can be expressed as follows.

[Equation 5] Also, on the envelope cross section of the intersection A of the straight line l ₁ and the straight line l ₂ (x
The positions x _A and z _A in the z coordinate) are as follows.

[Equation 6] From the above, when the value of the inclination angle ψ with respect to the traveling direction of the V-shaped grindstone 2 is obtained, the angles λ ₁ , λ ₂ and the coordinate position x _A , z of the point A in FIG. 4 are obtained from the above equations (7) and (9). _A and were derived. Conversely, when the angle ∠B ₁ AB ₂ = ω formed by the straight lines l ₁ and l ₂ in the envelope cross section is given, the inclination angle ψ of the V-shaped grindstone 2 in the traveling direction can be obtained as follows. That is,

[Equation 7]

Square both sides of equation (10) and arrange,
The following equation is obtained by using the relations such as the above equation (8).

[Equation 8] As is clear from FIG. 4, ω = π− (λ ₁ + λ ₂ ) ... (12) Therefore, the following equation is obtained.

[Equation 9] The following equation is obtained from the above equation and −π / 2 ≦ ψ ≦ π / 2 (14).

[Equation 10] In this way, the angle between the straight lines l ₁ and l ₂ ∠B ₁ AB
_{When 2} = ω was given, the inclination angle ψ of the V-shaped grindstone 2 in the traveling direction was derived. Next, we extend the above discussion to three-dimensional space. The reference coordinate system of the three-dimensional space is O ₀ −X ₀ Y ₀ Z ₀
far. The planes created by the left side and the right side of the V-shaped grindstone 2 are π ₁ and π ₂ , respectively, and are well known in the standard coordinate system.
Described in the standard system of sse, the following equation is obtained. π ₁ : l ₁ ′ x + m ₁ ′ y + n ₁ ′ z = p ₁ π ₂ : l ₂ ′ x + m ₂ ′ y + n ₂ ′ z = p ₂ (16)

Next, inside the envelope shape of the V-shaped grindstone 2, P
_r(X_r, Y_r, Z_r). Plane π₁, Π₂The envelope of
The unit normal vector from the outside to the inside of the figure is n₁, N
₂Express. P_r, O₀And the plane π₁, Π₂Positional relationship with
Focusing on the unit, the unit normal vector n₁, N₂Is given by
It if l_i′ X_r+ M_i′ Y_r+ N_i′ Z_r-P_i > 0, then n_i= [L_i′ M_i′ N_i′]^T if l_i′ X_r+ M_i′ Y_r+ N_i′ Z_r-P_i <0, then n_i= [-L_i′ -M_i'-N_i′]^T i = 1, 2 (17) At this time, the above-mentioned two planes π₁, Π₂The angle ω formed by
As shown. cos ω = −n₁・ N₂ (18) That is, ω = cos^-1(-N₁・ N₂) (0 ≤ ω ≤ π) (19) where · is the inner product of the vectors. Next, the reference coordinate system
Of each coordinate axis of the envelope cross-section coordinate system o-xyz described by
Position direction vector l_e, M_e, N_eAnd Figure
From 5, the unit direction vector l _e, M_e, N_eIs as follows
Can be expressed easily.

[Equation 11] Here, × is the cross product of vectors, and ‖ ・ ‖ is the Euclidean norm of vectors.

The angles λ ₁ and λ ₂ are obtained from the above equations (15) and (11). The unit direction vectors l _e and n _{e in} the x-axis and z-axis directions of the envelope cross-section coordinate system are the normal vectors n ₁ (n ₂ ) of the plane π ₁ (π ₂ ) around the y-axis of the envelope cross-section coordinate system. / 2-λ ₁ , -λ ₁ (λ ₂ -π / 2, λ ₂ )
It is rotated. That is, it becomes like the following formula.

[Equation 12] However, R (,) is a general rotation transformation matrix derived as follows. Here, we describe the general rotation transformation matrix. A transformation matrix indicating a rotation around an arbitrary vector k _{r at the} origin of coordinates is obtained. First, consider a coordinate system C in which the vector k _r matches the unit vector in the z direction, and define it as follows.

[Equation 13] Then, the rotation around the vector k _r becomes equal to the rotation around the z axis of the coordinate system C, and the following equation is obtained.

[Equation 14] However, θ is the rotation angle. Now, assuming that a coordinate system T expressing the reference coordinate system is given, the coordinate system X when expressing this by the coordinate system C can be expressed by the following equation.

[Equation 15] Rotating the coordinate system T around the vector k _r is equivalent to rotating the coordinate system X around the z axis of the coordinate system C, and therefore the following equation is established.

[Equation 16] The coordinate system C is unknown except that its z axis coincides with the vector k _r , but when expanded, it becomes a function of only the vector k _r and the rotation angle θ.

[Equation 17] That is, the above-mentioned R (,) is described by the above equation (21-6).

In this way, the unit direction vector of the envelope cross-section coordinate system is derived, and the direction of the trajectory straight line of the V-shaped grindstone 2 (the straight line through which the center of the V-shaped grindstone 2 passes) in the reference coordinate system is obtained. Next, the position of the straight line of the locus of the V-shaped grindstone 2 in the reference coordinate system (the point through which the straight line passes) is determined. here,
In FIG. 5, the envelope cross section (plane) including the point P _r is set to π ₃ , and the position of the intersection of the trajectory straight line of the V-shaped grindstone 2 and the plane π ₃ in the reference coordinate system is derived. Since the plane π ₃ includes the point P _r and the normal vector is m _e , the following equation is derived. π ₃ : l _me x + m _me y + n _me z = p ₃ (22) where l _me , m _me , and n _me are components of the unit direction vector in the y-axis direction of the envelope cross section, and are represented by the following equation. m _e = [l _me m _me n _me ] ^T (23) Further, the plane p ₃ is given by the following equation. p ₃ = l _me x _r + m _me y _r + n _me z _r (24) The intersection of the planes π ₁ , π ₂ and π ₃ corresponds to point A in FIG. 4. The intersection coordinates of the three planes expressed in the reference coordinate system are P _a =
[X _a y _a z _a ] ^T , the following equation is given.

[Equation 18] From this, the intersection point coordinate P _o = [x _o y ₀ z ₀ ] ^T between the plane π ₃ and the locus line of the V-shaped grindstone 2 can be given by the following equation.

[Formula 19] However, x _A and z _A are scalar quantities defined in (9) above.

Therefore, the equation of the trajectory straight line of the V-shaped grindstone 2 in the reference coordinate system is given by the following equation.

[Equation 20] In addition, the unit direction vector u _c of the rotation axis direction of the V-shaped grindstone 2
Is given by

[Equation 21] Subsequently, modeling of the NC grinder 1 is performed. The work (reference) coordinate system Σ _work is set at an arbitrary position on the work 3,
A coordinate system is given such that the center position of the V-shaped grindstone 2 is the origin and the rotational axis direction of the V-shaped grindstone 2 is z _n (see FIG. 6). The work transformation matrix representing the position and orientation of the n-coordinate (V-shaped grindstone 2) _viewed from the work coordinate system Σ _{work is} defined as ^work A _n . This ^homogenous transformation matrix ^work A _n is a function of m physical parameters q _k (link length, axis tilt, origin offset, etc.) of the NC grinder 1 and n servo parameters q _s (driving axis operation value). And can be shown as follows.

[Equation 22] The homogeneous transformation matrix ^work A _{n corresponds} to the shape generation model M, and the physical parameter q _k corresponds to the machine parameter q. Here, a modeling example of the 5-axis NC grinder 1 will be described. Regarding the 5-axis NC grinder 1 as shown in FIG. 7, the relationship between the position and orientation between adjacent coordinate systems will be described below by using the homogenous transformation. Here, the work coordinate system Σ _work is a coordinate system set at an arbitrary position on the work 3.

[Equation 23] The transformation matrix ^i-1 A _i is a homogeneous transformation matrix that defines the relationship between the coordinate systems Σ _i-1 and Σ _i, and Rot (·, ·) is the rotation,
Trans (.,.,.) Is a coordinate transformation matrix expressing translation and is defined as follows.

[Equation 24] The homogeneous transformation matrix ^work A ₅ describing the link 5 coordinate system Σ _{5 viewed} from the work coordinate system Σ _work is as follows.

[Equation 25] Derivation of machine differences in this algorithm is equivalent to finding m physical parameters q _k .

Next, the test grinding for deriving the machine difference will be described. In the above, with respect to the work coordinate system Σ _work , the locus of the central position of the V-shaped grindstone 2 and the rotational axis direction of the V-shaped grindstone 2 are obtained from the wound forming shape when grinding is performed without changing the attitude of the V-shaped grindstone 2. It was shown that To derive the machine difference, V
It is necessary to use one point on the locus of the center position of the die wheel 2 as reference data. Therefore, in the present invention, as shown in FIG. 8, grinding is performed twice in different directions in the same posture, and the center position and direction of the V-shaped grindstone 2 are derived as reference data by these two wound forming shapes. To keep the V-shaped grindstone 2 in a constant posture,
The rotary axis of the NC grinder 1 is set to a constant value, and only the linear axis is operated to create a test grinding shape. At this time, the V-shaped grindstone 2 is moved from the point P _{1s in} FIG. 8 to the point P _1e to create the creation surface SP1. Next, the V-shaped grindstone 2 is moved from the point P _{2s in} FIG. 8 to P _2e to create the creation surface SP2.
These creation surfaces SP1 and SP2 correspond to the second shape creation surface data D _di . In this case, the straight line t _r1, t _r2 sets the operation data (NC data D _si) so as not to be parallel, one only common normals to the two straight lines tr _1, tr ₂ as shown in FIG. 8 Will exist. The midpoint of the common normal line is defined as P _r, the reference point of the machine difference derives P _r. Here, for ease of analysis, left V-shaped grindstone ₂ is defined as being in the positive direction of the z _n axis, _below, to derive the data and variables defining the point P _r. (A) Derivation of the second reference point P _r1 The V-shaped grindstone 2 in the work coordinate system Σ _work by three-dimensionally measuring the wound forming shapes SP1 and SP2 as shown in FIG.
The center passage straight lines tr ₁ and tr ₂ are derived from the above equation (27) as follows. That is,

[Equation 26] Here, the point P _n is the straight line tr ₁ , t passing through the center of the V-shaped grindstone 2.
It is the midpoint of the common normal of r ₂ and is derived from the geometrical relationship as follows. This middle point P _n corresponds to the second reference point P _r2 .

[0016]

[Equation 27] The unit direction vector of the z _n axis at this time is derived from the above equation (28). That is,

[Equation 28] However, the unit direction vectors n _ei and l _ei are the creation plane SP
It is a unit direction vector of _i (i = 1, 2) calculated by the above equation (21). What should be noted here is that since the V-shaped grindstone 2 rotates, the directions of the x _n and y _n axes have no meaning. Therefore, in order to ignore the directions of the x _n and y _n axes, the first and second angles (ε1, ε) among the three Euler angles generally used to describe the rotational motion of a rigid body
2) is used. Here, the Euler angle is expressed by the following equation (see FIG. 9).

[Equation 29] That is, in the above equation (32), z _n = [l _zn m _zn n _zn ] ^T
Then, the following equation is derived from the above equation (33-3).

[Equation 30] The equations (31) and (33) serve as reference data in the work coordinate system. Below, these are summarized and described as follows.

[Equation 31] (B) Derivation of the first reference point P _{r1 In} the above formula (29), m physical parameters q _k and n servos of the NC grinding machine 1 are calculated. Given the parameter q _s , a homogeneous transformation matrix ^work A _n representing the position and orientation of the n-coordinate (V-shaped grindstone 2) viewed from the work coordinate system is obtained. here,
The servo parameter q _s that defines the point P _n is derived (the physical parameter q _k is a machine difference derived using this servo parameter q _s ).

Now, the NC grinding machine 1 has three linear motion axes XYZ.
Assuming that each axis has {X_is, Y _is, Z_is} →
{X_ie, Y_ie, Z_ie} (I = 1, 2)
Let Here, there is one coordinate system with the value of the linear axis as the coordinate axis.
Construct a linear space of, and use this linear space as the NC data space.
Define. NC data D in this NC data space_siThe same
Transform matrix^workA_nTo perform coordinate transformation calculation using
More creative side SP₁′, SP₂Create ′. Creation side SP
₁′, SP₂′ Is the first shape creation surface data D_miEquivalent to
It These creation SP₁′, SP₂'From V type grindstone 2
Find the straight line passing through the center of. This straight line passing through the center is the linear axis
The straight line (line
Min) l_N1,l_N2Becomes Point P in FIG._nNC data equivalent to
Data D_si(Servo parameter q_sIs a straight line
 l_N1,l_N2Midpoint P of the common normal of_NrBecomes This midpoint P
_NrCorresponds to the first reference point. 2 shifts in NC data space
Line l_N1,l _N2Is expressed by the following equation.

[Equation 32] Where β _i is the media variable,

[Expression 33] Is. At this time, the middle point P _Nr of the common _normals of the straight lines l _{N1 and} l _N2
Is given by the following equation from the geometrical relation.

[Equation 34] X _Nr , Y _Nr , and Z _{Nr in the} above equation (37) are NC servo parameters corresponding to the reference point P _r of the work coordinate system. In the above description, the NC linear motion shaft is three axes, but if the linear motion shaft is 2 or less, unnecessary variables may be set to zero. Reference point P for test grinding
The servo parameter q _{s at r} is the NC servo parameter X _Nr ,
It is only necessary to substitute Y _Nr and Z _Nr with respect to the rotation axis component, and to fix the values fixed at the time of grinding into the corresponding variables.
The following equation is obtained by writing down the homogeneous transformation matrix of the above equation (29) for each element.

[Equation 35]

Each element of the above equation (38) is a function of the parameters q _k and q _s . The homogeneous transformation matrix of the equation (38) indicates the position and orientation in the work coordinate system.
As for the posture, the first and second Euler angles may be used as in the equation (33). Therefore, the position and orientation X _NC of the V-shaped grindstone 2 expressed by the above equation (38) are given by the following equation.

[Equation 36] Since the servo parameter q _s has already been given by the test grinding, here, the reference data X _w in the work coordinates of the formula (34) and the position / posture X _NC of the V-shaped grindstone 2 of the formula (39) are used. To determine the physical parameters q _k of the NC grinder 1 (this is the first and second
Corresponding to the correction of the machine parameter q by comparing the reference points P _r1 and P _r2 . The machine difference derivation calculation algorithm is described below. For this preparation, first (39) above
Derive the differential relation of the formula.

[Equation 37] R (≧ m) pieces of reference data X _w and servo parameters q _s are prepared for deriving the machine difference, and X _wi , q _si (i = 1, ...
Number it like R). Using this reference data and parameters, a 1 × 5R constant vector X _{D, a} 1 × 5R variable vector X _C and an n × R variable matrix Q (q _k ) are defined as follows.

[Equation 38] The X _NC and J are given by the equations (39) and (40), respectively.

Under the above preparations, the physical parameter q _k is _obtained by using the iterative solution method. The calculation algorithm is shown below. (Iterative Calculation Algorithm) Step 1 An initial value q _k (0) of the physical parameter q _k and a convergence determination reference scalar quantity ε (> 0) are given, and i = 0. Step two

[Formula 39] ,

[Formula 40] Then end. Step 3

[Formula 41] ,

[Equation 42] Using the pseudo-inverse matrix [Q (i)] ⁺ of the matrix Q (i) from

[Equation 43] The parameter differential Δq _k (i) is calculated by Step 4

[Equation 44] Return to step 2.

By performing the iterative calculation in this way, the physical parameter q _k can be obtained. As described above, according to the present embodiment, the respective reference points of the shape generation model and the processing tool origin (link tip) of the actual processing shape are uniquely derived from the shape of the processing target processed by the processing tool, By performing the correction calculation of the machine parameter q using these reference points, the absolute value of the machine parameter q can be uniquely derived. As a result, it is possible to obtain a machine parameter correction method and a machine parameter correction apparatus that can uniquely derive the absolute value of the machine parameter. It should be noted that in the above embodiment, the machine tool has a 5-axis N
Although the C grinder and the V-shaped grindstone as the processing tool have been described as examples, there is no problem in using other types of machine tools or other types of processing tools.

[0021]

Since the method and apparatus for correcting the machine parameters of the machine tool according to the present invention are configured as described above, the shape creation model and the actual model are calculated from the shape of the object to be machined by the machining tool. The reference point of the machining tool origin (link tip) of the machining shape is uniquely derived.
By performing the correction calculation of the machine parameter using these reference points, the absolute value of the machine parameter can be uniquely derived. As a result, it is possible to obtain a machine parameter correction method and a machine parameter correction apparatus that can uniquely derive the absolute value of the machine parameter.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic flow of a method for correcting machine parameters of a machine tool according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a correction device A by the above correction method.

FIG. 3 is an explanatory view showing a schematic shape of a V-shaped grindstone.

FIG. 4 is an explanatory diagram showing a relationship between a trajectory of a V-shaped grindstone and an envelope cross section.

FIG. 5 is an explanatory view showing a wound forming shape with a V-shaped grindstone.

FIG. 6 is an explanatory diagram showing a coordinate system of an NC machine tool.

FIG. 7 is an explanatory diagram showing a coordinate system and machine parameters of a 5-axis NC grinding machine.

FIG. 8 is an explanatory diagram showing a test grinding state.

FIG. 9 is an explanatory diagram showing Euler angles.

FIG. 10 is an explanatory diagram showing a schematic flow of an example of a conventional method of correcting machine parameters of a machine tool.

FIG. 11 is an explanatory diagram showing a relationship between a trajectory of a conventional machining tool and an envelope surface.

[Explanation of symbols]

A ... Correction device 1 ... NC grinder (corresponding to machine tool) 2 ... Grinding stone (V-shaped grindstone) (corresponding to machining tool) 3 ... Work (corresponding to machining target) 4 ... Three-dimensional measuring machine (corresponding to measuring means) ) 5 ... Model input circuit (corresponding to model input means) 6 ... Data input circuit (corresponding to data input means) 7 ... Conversion circuit (corresponding to conversion means) 8 ... Correction circuit (corresponding to correction means) 9 ... Memory 10 ... First arithmetic circuit (corresponding to first arithmetic means) 11 ... Second arithmetic circuit (corresponding to second arithmetic means) q ... Machine parameter M ... Shape generation model _Dsi ... NC data (machining tool trajectory data) D _mi ... 1st shape creation surface data D _di ... 2nd shape creation surface data P _r1 ... 1st reference point P _r2 ... 2nd reference point

Claims (2)

[Claims] 1. Compensation of machine parameters of a machine tool for compensating machine parameters for deciding operating characteristics of a machine tool for machining a workpiece by a machining tool attached to the tip of a program-controlled mechanism to form a shape. A method for inputting a shape generation model for coordinate conversion calculation, which models the relationship between the trajectory of the processing tool and the processing target shape of the processing target processed by the processing tool including the machine parameters. , Input the trajectory data of the above machining tool,
Using the shape generation model, the trajectory data is converted into first shape generation surface data in the coordinate system of the workpiece, and the machine tool is driven based on the trajectory data to realize the workpiece. The shape generation surface obtained by processing is three-dimensionally measured to obtain the second shape generation surface data of the coordinate system of the processing object, and the first shape generation surface data and the second shape generation surface data are obtained. In a method for correcting machine parameters of a machine tool that corrects the machine parameters included in the shape generation model based on the following, the processing tool has a plurality of processing surfaces for obtaining a plurality of second shape generation surface data. In addition to making it a processing tool, a plurality of first shape generation surface data are stored in a memory, and the machine parameters included in the shape generation model are corrected based on the plurality of first shape generation surface data. A first reference point for calculating a second reference point for correcting the machine parameter included in the shape generation model based on the plurality of second shape generation surface data corresponding to the machining tool. A method for correcting a machine parameter of a machine tool, which comprises performing a calculation to correct the machine parameter by comparing the first reference point and the second reference point. 2. A machine parameter compensating device for a machine tool for compensating a machine parameter for determining an operating characteristic of a machine tool for machining a machining target by a machining tool attached to the tip of a program-controlled mechanism. Which is a model for inputting a shape generation model for coordinate conversion calculation that models the relationship between the trajectory of the processing tool and the processing target shape of the processing target processed by the processing tool, including the machine parameters. Input means, data input means for inputting the trajectory data of the processing tool, and shape generation model input by the model input means are used to convert the trajectory data input by the data input means into the coordinate system of the workpiece. Converting means for converting into the first shape generating surface data, and the processing machine based on the trajectory data input by the data inputting means. Measuring means for three-dimensionally measuring a shape generating surface obtained by actually processing the object to be processed by driving a machine to obtain second shape generating surface data of a coordinate system of the object, and the conversion. The first shape generation surface data converted by the means and the second shape generation surface data measured by the measuring means.
A machine parameter compensating device for a machine tool, comprising: compensating means for compensating the machine parameter contained in the shape generating model based on the shape generating surface data of
The processing tool is a processing tool having a plurality of processing surfaces for obtaining a plurality of second shape generation surface data, and a memory for fetching a plurality of first shape generation surface data converted by the conversion means, The first calculation means for calculating the first reference point for correcting the machine parameter included in the shape generation model based on the plurality of first shape generation surface data stored in the memory, and the measuring means. Second calculating means for calculating a second reference point for correcting a machine parameter included in the shape generating model based on the plurality of second shape generating surface data corresponding to the measured machining tools; And the first reference point calculated by the first calculation means and the second reference point calculated by the second calculation means are compared by the correction means. Correction apparatus of the machine parameters of the machine tool, characterized in that to correct the parameters.