JPH10177406A - Controller for five-axis working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a five axis working machine for operating working by making a program commanding point coincident with an actual point to be cut, and shifting a cutting point at a ball end mill side from the top end. SOLUTION: A tool attitude (a normal for a work surface) for operating working for a program instructing point 7 at the top end of a ball end mill 4 is designated as I, J, K, or a rotary 2 axial value by using a designating direction tool length correcting function. An angle condition for inclining a tool 1' (an inclination for a reference attitude α and an angle for a working progressing direction β) is designated by a program or parameter by using a tool axial direction TL' as a reference in this case. A correction vector <q> for shifting a cutting point at the ball end miss side from the top end without breaking a condition that the program commanding point 7 is an actual point to be cut is calculated, a point added to the position of the program commanding point 7 is defined as the position of a control point 3 and the movement target point (position) of basic three axes. Also, the rotary two axial value for the tool axial direction TL in this case is calculated, and defined as the movement target point (attitude) of the rotary two axes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for controlling a five-axis machine tool (five-axis machining machine) having three basic axes and two rotary axes for rotating a tool. The present invention relates to a numerical controller having a function of correcting a tool axis direction of the five-axis processing machine to perform appropriate processing.

[0002]

2. Description of the Related Art As shown in FIG.
It is known as a processing machine having three basic axes and two rotating axes for rotating a tool. In the figure, a tool 1 performs cutting of a workpiece W by rotating a tool 4 attached to a tip portion around a tool axis TL (arrow SP). The tool mounting portion 2 driven by the C-axis (the rotation axis around the Z-axis direction) is provided with a tool support shaft passing through the center of rotation 3 and perpendicular to the Z-axis, and is rotatable around the tool support shaft. The tool 1 is attached.

As shown in FIG. 1, according to the custom that the rotation axes around the X-axis and the Y-axis are called the A-axis and the B-axis, respectively, according to the rotation position of the C-axis, the rotation of the 5-axis machine is changed. The two axes can also be referred to as “C axis and A axis” or “C axis and B axis”, and are therefore referred to as A / B axis in this specification. The three basic axes are assigned to a table TB on which the workpiece W is placed or a drive mechanism (not shown) equipped with the tool mounting unit 2.

When the servomotors for driving these five axes are controlled by a numerical controller, the control point 3 is set as the rotation center of the tool 1 and the tip 5 of the ball end mill 4 is cut using the tool length correction function in the designated direction. A method of matching the position is used. This designated direction tool length correction function is a function executed in the following procedure.

(1) As shown in FIG. 1B, a set of three values (I, J, K) defining a vector D of an arbitrary length
Is used to specify the direction of the tool axis TL. The direction of the tool axis TL is from the ball end mill tip 5 to the control point (rotation center) 3
To go to. For example, according to the illustrated example, (1.00, 1.80, 6.00) is designated.

The specification of (I, J, K) may be specified in a machining program or by a parameter setting function different from the machining program. When the program playback operation is performed with the numerical controller in the designated direction tool length correction mode, the position of the tip 5 of the ball end mill coincides with the machining point designated by the machining program, and (I, J,
K) so that the direction of the tool axis TL specified in
Two rotation axes (C axis and A / B axis) and three basic axes are controlled.
For the control of the three basic axes, data of a preset tool length L (distance between the control point 3 and the tip end 5 of the ball end mill) is used in addition to (I, J, K).

As described above, if the tool length correction function in the designated direction is used, cutting can be performed while moving the tip 5 of the ball end mill along the path designated by the machining program while maintaining the desired tool posture. . That is,
The designated direction tool length correction function is a function for correcting the position (basic three axes) and posture (two rotation axes) of the control point 3 so as to realize the specified tool posture by regarding the ball end mill tip 5 as a cutting point. is there.

The problem here is that, except for special cases, the ball end mill tip 5 is not suitable for actually cutting. This is because the ball end mill tip 5 is on the rotation (rotation) axis of the ball end mill itself, and the relative speed between the ball end mill and the work surface becomes "0" even if the ball end mill rotates (rotation).

[0009] Another problem is that the direction of the tool axis TL of the tool 1 is changed to (I,
J, K), as shown in FIG. 2, except when it is perpendicular to the work surface.
Cannot correspond to the desired point 7 to be cut on the work surface. In the illustrated model, the work surface near the point 8 deviating from the ball end mill tip 5 becomes a practical cutting point, and deviates from the desired point 7 to be cut. In addition, since the point 8 is located at a position below the work surface in principle, it cannot be said to be appropriate in that sense.

Conventionally, in order to deal with these problems, in actual machining, the operator shifts the minute position of the control point 3 based on experience and intuition, finely corrects the set value of the tool length L, and uses machining point data of the machining program. In addition, a fine adjustment operation including a fine correction is performed, and as shown in FIG. 3, the point 6 on the ball end mill surface displaced from the ball end mill tip 5 is intended to match the desired cutting point 7. . However, such fine adjustment work is complicated, and the processing quality tends to vary depending on the skill level of the operator.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to provide a control device of a 5-axis machining machine with a correction function, which is an improvement over the above-mentioned conventional specified direction tool length correction function, to provide a desired cutting point (typically In this case, the cutting point on the ball end mill side can be shifted from the tip without changing the condition for setting the cutting point at the cutting end point without breaking the condition for setting the tool. Further, through this, the present invention aims to improve the efficiency of the machining operation using the five-axis machining machine and improve and stabilize the machining quality. In this specification, the above correction is called a cutting point correction, and the function is called a cutting point correction function.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to machining by shifting the cutting point on the ball end mill side from the tip while making the program command point coincide with the actual cutting point. To provide a control device capable of controlling a 5-axis machine.

A control device according to the present invention comprises three basic axes:
A 5-axis machine having a rotary shaft for rotating a tool equipped with a ball end mill at a tip thereof and having a control point at a base of the tool is controlled. A means for storing a machining program and a machining program are provided. Means for reproducing and outputting a movement command for operating the 5-axis machining machine; and means for storing tool reference attitude data representing a tool reference attitude in which the axis direction of the tool coincides with the normal direction to the work surface. In addition, the following means are provided.

(1) Means for storing tool inclination condition data representing a tool posture inclined from the tool reference posture, tool reference posture data, tool inclination condition data, and data representing a machining progress direction determined from a machining program. Based on the control point, a position correction amount of three basic axes required to realize a state where the tool is tilted in accordance with the tool tilt condition data under a condition that a command point determined from a machining program is a cut point is calculated with respect to the control point. (2) Based on data representing a command point and the calculated position correction amount of the basic three axes, means for determining a movement target point of the basic three axes with respect to the control point and two rotation axes based on tool tilt condition data Means for determining the movement target point of the tool The storage of the tool reference attitude data by the means for storing the tool reference attitude data indicates the normal direction to the work surface Setting parameters describing the component ratio of the vector, or,
This can be performed by setting parameters describing values of two rotation axes so that the axis direction of the tool is perpendicular to the work surface.

The tool tilt condition data may be specified in a machining program, or may be set by setting parameters different from the machining program.

The control device of the present invention uses the conventional designated direction tool length correction function to change the tool attitude (normal to the work surface) for machining at the program command point 7 at the tip of the ball end mill to the vector component ratios I and J. , K or rotation 2
Specify by axis value. Based on the tool axis direction at this time, an angle condition for tilting the tool, more specifically, an inclination angle α with respect to the reference posture and an angle β with respect to the machining progress direction are designated by a program or parameters.

In the control device, a correction amount (vector amount) is calculated so as to shift the cutting point on the ball end mill side from the tip without violating the condition that the program command point is an actual cut point. A point shifted from the point according to the correction amount is set as the position of the control point 3, and is set as a movement target point (position) of the three basic axes. Further, a rotation two-axis value corresponding to the tool axis direction at that time is obtained, and is set as a movement target point (posture) of the rotation two axes. Then, a command for moving these five axes to the movement target point is output to each axis servo of the five-axis machine.

[0018]

FIG. 4 is a main block diagram showing a hardware configuration of a numerical control device (CNC) as a control device according to one embodiment of the present invention. In the figure, a numerical controller (CN) denoted by reference numeral 10
C) includes a processor 11 that controls the entire system.
The processor 11 reads a system program stored in the ROM 12 via the bus 21 and controls the entire numerical controller (CNC) 10 according to the system program. For example, a RAM composed of a DRAM
13 temporarily stores calculation data, display data, and the like.

The CMOS 14 stores a processing program and various parameters. Also, a program for performing cutting point correction described later and related parameters are stored. Hereinafter, these programs are collectively referred to as an operation program. The CMOS 14 is backed up by a battery (not shown), and a numerical controller (CNC) 10
Functions as a non-volatile memory in which data is not erased even when the power of the device is turned off.

The interface 15 is provided for inputting and outputting to and from an external device, to which an external device 31 such as an offline programming device or a printer is connected. The data of the operation program created by the off-line programming device is read into the numerical controller (CNC) 10 via the interface 15. Numerical control unit (CN
C) The data of the operation program edited in 10 can be output by, for example, a printer.

A PMC (Programmable Machine Controller) 16 is built in the numerical controller (CNC) 10 and controls the machine with a sequence program created in a ladder format. That is, according to the M function, the S function, and the T function specified by the operation program, these are converted into signals required by the sequence program and output from the I / O unit 17 to the machine side (here, a 5-axis machining machine). This output signal activates various operating units (air cylinder, screw, electric actuator, etc.) on the machine side. In addition, receiving signals from various switches on the machine side and switches on the machine operation panel,
Necessary processing is performed and passed to the processor 11.

The graphic control circuit 18 controls each axis (5
The digital data such as the current position of the axis (axis), alarms, parameters, and image data are converted into image signals and output. This image signal is sent to the display device 26 of the CRT / MDI unit 25 and displayed on the display device 26. The interface 19 receives data from the keyboard 27 in the CRT / MDI unit 25 and passes the data to the processor 11.

The interface 20 is connected to the manual pulse generator 32 and receives a pulse from the manual pulse generator 32. The manual pulse generator 32 is mounted on the machine operation panel and can be used for manually moving and positioning the movable part of the machine body including the work table.

The axis control circuits 41 to 45 are
And outputs the command for each axis to the servo amplifiers 51-55. Servo amplifier 51
-55 drive the servomotors 61-65 of each axis in response to the movement command. Servo motor 61 for each of these axes
Drives the basic three axes (X axis, Y axis, Z axis) and two rotation axes (C axis, A / B axis) of the processing machine.

Reference numeral 651 denotes a pulse coder as a position detector attached to the servomotor 65 for driving the A / B axes. Although not shown, servomotors 61 to 6 for the other axes are omitted.
4 is also provided with a pulse coder. The output pulses of these pulse coders are used to generate a position feedback signal and a velocity feedback signal.

The spindle control circuit 71 receives a spindle rotation command and outputs a spindle speed signal to the spindle amplifier 72. The spindle amplifier 72 receives the spindle speed signal and receives a spindle motor 73
Is rotated at the commanded rotation speed, and the ball end mill 4 of the tool 1 of the 5-axis machine is rotated.

The hardware configuration described above is not particularly different from a normal numerical controller. That is, the present invention does not require a new condition for the hardware configuration of the numerical control device, and it suffices if software means for executing the cutting point correction described below is provided. Hereinafter, the description will be given in order from the principle (calculation contents) of the cutting point correction.

Now, as shown in FIG. 5, the tool posture (I, I) at which the tip of the ball end mill 4 performs the machining for the desired cutting point (machining program command point) 7 using the designated direction tool length correction function. J, K) are specified. The tool at this time is denoted by 1 '(broken line), and the tool axis is T
If L ′ and the tip of the ball end mill 4 are represented by 5 ′, respectively, the tool axis TL ′ is perpendicular to the work surface.

Based on this state (tool reference posture),
It is considered that the cutting point on the ball end mill 4 is shifted from the tip by inclining the tool 1 ′ by a newly specified inclination angle without breaking the condition that the desired cutting point 7 becomes the cutting point. In FIG. 5, the tool after tilting is represented by reference numeral 1 (solid line), the tool axis is represented by reference numeral TL, the tip of the ball end mill 4 is represented by reference numeral 5, and the control point is represented by reference numeral 3. The following symbols are used in relation to the state before and after the inclination.

R: radius of the ball end mill 4 l: distance from the center 9 of the ball end mill 4 to the control point 3 <e>: unit vector defined by (I, J, K) before inclining, here a program It is also a normal vector set with respect to the work surface at the command point 7. <Q>: A vector from the program command point 7 toward the control point 3 after the inclination, and is a correction vector to be obtained. α: inclination angle of the tool 1 measured from the normal direction to the work surface at the program command point 7 The three-dimensional relationship between the tool axis direction after tilting, the normal vector, etc. in FIG. 5 and the tool advancing direction specified by the program FIG. 6 shows the result of the drawing. The following symbols are further used in connection with this figure.

<P>: A unit vector representing a tool advancing direction specified by a program <N>: A tool advancing direction vector <p> and a normal vector <
vector representing the direction perpendicular to e> β: the inclination angle of the tool 1 measured from the tool advancing direction specified by the program Here, both α and β are specified by the program, or the numerical controller 10 is separately set by parameter setting. This is the amount that can be taught to. The radius r of the ball end mill 4 and the distance 1 from the center 9 of the ball end mill 4 to the control point 3 are set in the numerical controller 10 in advance. Further, (I, J, K) is set in the numerical controller 10 so that it indicates the direction of the normal to the work surface. However, instead of setting the values of I, J, and K, two rotation axes (C axis and A / A
The rotation position (θ _{A / B0} , θ _C0 ) of the B-axis may be set (can be converted into I, J, K within the numerical controller 10).

Hereinafter, the description will be continued assuming that the values of I, J, and K have been set or have been obtained by conversion calculation inside the numerical controller 10. Each component e _x of the normal vectors _{<e>, e y, e} z is, I, J, is expressed by the following equation (1) using the K.

[0033]

(Equation 1) On the other hand, the tool traveling direction vector <p> and the normal vector <e
> Each of the components N _x ,
N _y and N _z are represented by <Δp> = (Δx, Δy, Δz) and <e
> From the outer product of>. _{N = (N x, N y} , N z) = ((e y · Δz-e z Δy), (e z · Δx-e x Δz), (e x · Δ y-e y Δx)) ··・ (2) This is normalized to <n> = (n ₁ , n ₂ , n ₃ )
Then, the following equation (3) is obtained.

[0034]

(Equation 2) Here, what normalized the correction vector <q> is <d>
[M ₁ ] represents a matrix representing the rotation of the angle α with <n> as the central axis and [M ₂ ] represents a matrix representing the rotation of the angle β with <e> as the central axis. Is represented by the following equation (4). <D> = [M ₁ ] [M ₂ ] <e> (4) Then, [M ₁ ] and [M ₂ ] are calculated using the components of <n> and <e> and α and β. It is expressed by the following equations (5) and (6).

[0035]

(Equation 3) The correction amounts of the three basic axes X, Y, and Z with respect to the program command point 7 for performing the cutting point correction are nothing but the components ΔX, ΔY, and ΔZ of the correction vector q. Accordingly, the correction amounts of the three basic axes X, Y and Z with respect to the program command point 7 to be obtained are collectively expressed by the following equation (7). <Q> = ([Delta] X, [Delta] Y, [Delta] Z) = r <e> +1 <d> (7) Further, a two-rotation axis A that gives the direction of the tool axis direction TL of the tool 1 corresponding to <q> / B axis and C axis values θ _{A / B} , θ
_C is expressed by the following equations (8) and (9), respectively.

[0036]

(Equation 4) As described above, if the above (7) to (9) are subjected to the cutting point correction calculation for an arbitrary program command point (generally, a desired cutting point) 7 inside the numerical control device 10, the program command A cutting point correction in which the cutting point on the ball end mill 4 side is shifted from the tip according to the designated inclination condition can be achieved without violating the condition that the point 7 becomes the actual cutting point.
The inclination conditions are the data of the normal direction to the work surface and the inclination angle α,
The data of β may be given to the numerical controller 10.

As described above, the data in the normal direction to the workpiece surface is obtained by designating the tool axis direction vector components I, J, K using the designated direction tool length correction function or by rotating two axes (A / B).
Numerical control device 1 by designating the rotational position of (A and C axes)
0 can be given. These designations may be made by writing into the program or by setting parameters.

FIG. 7 is a flowchart outlining the processing performed by the numerical controller 10 internally. This processing is
It is performed for each calculation cycle of the movement target position of each axis (5 axes),
As the values of I, J, and K or the designated values θ _{A / B0} and θ _C0 of the two rotation axes used in this case, the values written in the machining program or the values separately set as parameters are used. The movement target point before performing the correction according to the present invention is normally calculated from a machining program, but may be calculated in accordance with a manual command and a movement command.

The main points of each of the steps S1 to S9 are as follows. Step S1: specified I, J, K or θ
_{Based on A / B0} and θ _C0 , calculation of tool length compensation in the designated direction is performed. In the case of designation by I, J, K, the correction amounts ΔX, ΔY, ΔZ of the three basic axes and the two-axis rotation values θ _{A / B0} , θ _C0 are obtained.
In the case of designation by θ _{A / B0} and θ _C0 , the correction amount Δ
X, ΔY, ΔZ are determined. ΔX ₀ , ΔY ₀ , ΔZ ₀ , θ _{A / B0} , θ _C0 when I, J, K are designated are calculated by the following equations (10) to (14).

[0040]

(Equation 5) Step S2: Command representing cutting point correction (here, G4
1.9), that is, whether (α, β) is specified in the program or parameter. If yes, go to step S3; if no, go to step S4. Step S3: The flag F indicating whether the cutting point correction is executed / not executed is inverted or rewritten to set F = 1 (execution). (Reverse or rewrite).

Step S4: It is checked whether or not there is a command (here, G40 is exemplified) indicating the cancellation of the cutting point correction. If yes, go to step S5; if no, go to step S6. Step S5: The flag F indicating whether the cutting point correction is executed / not executed is set to F = 0 (not executed) by inversion or rewriting.

Step S6: The value of the flag F is checked. If F = 1, the process proceeds to step S7, and if F = 0, the process proceeds to step S9. Step S7: The above-described (1) to (9) calculations are performed based on the specified α and β, and the correction amounts ΔX and Δ of the three basic axes are calculated.
Y, ΔZ and the two-axis rotation values θ _{A / B} , θ _C are obtained.

Step S8: With respect to each axis (5 axes), a movement command is generated with the position / posture obtained by correcting the program command point at the cutting point as the movement target point, passed to the servo, and the processing for one calculation cycle is completed. . Assuming that the position component of the program command point is (x, y, z), each axis component of the movement target point is (x
+ ΔX, y + ΔY, z + ΔZ; θ _{A / B} , θ _C ).

Step S9: With respect to each axis (5 axes), a movement command is generated with the position and orientation obtained by correcting the program command point in the designated direction tool length as the movement target point, and passed to the servo.
The processing for the calculation cycle ends. Assuming that the position component of the program command point is (x, y, z), the respective axis components of the movement target point are (x + ΔX 0, y + Δ
_{Y0, z + ΔZ0; θ A} / B0, the theta _C0).

[0045]

According to the present invention, the control device of the 5-axis machine has a cutting point correction function for automatically matching a point on the surface of the ball end mill deviated from the end of the ball end mill with a desired point to be cut. Therefore, it is possible to improve the efficiency of the machining operation using the 5-axis machining machine and to improve and stabilize the machining quality.

[Brief description of the drawings]

FIG. 1 (a) is a diagram illustrating an axis configuration of a processing machine, and FIG. 1 (b) is a diagram illustrating I, J, and K in tool length correction in a designated direction.
FIG. 9 is a diagram for explaining the specification of.

FIG. 2 is a diagram illustrating a problem with a designated direction tool length correction function.

FIG. 3 is a diagram illustrating a state in which a point on the surface of the ball end mill shifted from the tip of the ball end mill coincides with a desired cutting point 7;

FIG. 4 is a main block diagram showing a hardware configuration of a numerical controller (CNC) according to an embodiment of the present invention.

FIG. 5 is a diagram showing a tool posture in which machining is performed at a tip of a ball end mill with respect to a desired point to be cut (a machining program command point) without breaking a condition that the desired point to be cut is a point to be cut;
It is a figure explaining the state where the cutting point of the tool side was shifted by inclining the tool.

6 is a diagram in which a tool axis direction, a normal vector, and the like after tilting in FIG. 5 are three-dimensionally redrawn in relation to a tool advancing direction specified by a program.

FIG. 7 is a flowchart outlining the processing performed by the numerical controller.

[Explanation of symbols]

1, 1 'Tool 2 Tool mounting part 3 Rotation center 4 Ball end mill 5 Ball end mill tip 6 Point on ball end mill surface shifted from ball end mill tip 7 Desired cutting point (program command point) 10 Numerical controller (CNC) 11 Processor 12 ROM 13 RAM 14 CMOS 15 Interface 16 PMC (Programmable Machine Controller) 17 I / O unit 18 Graphic control circuit 19 Interface 20 Interface 21 Bus 25 CRT / MDI unit 26 Display device 27 Keyboard 31 External device 32 Manual pulse generation Unit 41 to 45 Axis control circuit 51 to 55 Servo amplifier 61 to 65 Servo motor 651 Pulse coder 71 Spindle control circuit 72 Spindle amplifier 73 Spindle motor L, TL 'the tool axis W work TB table

Claims (5)

[Claims] 1. A control device for a five-axis machine having three basic axes, two rotating axes for rotating a tool equipped with a ball end mill at a tip thereof, and a control point at a base of the tool, Means for storing a machining program; means for reproducing the machining program to output a movement command for operating the 5-axis machining apparatus; and a tool reference in which the axial direction of the tool coincides with the normal direction to the work surface. Means for storing tool reference attitude data indicating the attitude; means for storing tool tilt condition data indicating a tool attitude tilted from the tool reference attitude; the tool reference attitude data; tool tilt condition data; and the machining program Based on the data indicating the machining progress direction determined from the above, according to the tool inclination condition data under the condition that the command point determined from the machining program is the point to be cut. Means for calculating a basic three-axis position correction amount necessary to realize the state in which the tool is tilted, with respect to the control point; data representing the command point and the calculated basic three-axis position correction amount The control of the 5-axis machining machine, comprising: means for determining a basic three-axis movement target point for the control point based on the control point; and means for determining a rotation two-axis movement target point based on the tool tilt condition data. apparatus. 2. The storage of the tool reference attitude data by the means for storing the tool reference attitude data is performed by setting a parameter describing a component ratio of a vector representing a normal direction to the work surface. 5. The control device for a 5-axis machine described in 1. above. 3. The storage of the tool reference attitude data by the means for storing the tool reference attitude data describes values of the two rotation axes such that an axis direction of the tool is perpendicular to the work surface. The control device for a five-axis machine according to claim 1, wherein the control is performed by setting a parameter. 4. The tool inclination condition data is included in the machining program, and the means for storing the machining program also serves as a means for storing the tool inclination condition data. 5. The control device for a 5-axis machine described in 1. above. 5. The storage of the tool tilt condition data by the means for storing the tool tilt condition data is performed by setting a parameter describing the tool tilt condition.
A control device for a five-axis machine according to claim 1.