JPH0454604A - Three-dimensional tool diameter correcting system - Google Patents

Abstract

PURPOSE:To simply execute the tool diameter correction by adding a second tool diameter correction vector to a program path deriving a final tool path and interpolating the tool path by an interpolating means. CONSTITUTION:A vector calculating means 105 reads the present position of a B shaft for controlling a rotary head 2 and the present position of a C shaft from a register 103 and a register 104, and derives a tool direction vector Vt of a tool 5. Subsequently, a plane arithmetic means 106 computes an offset plane S being vertical to the vector Vt. This offset plane S is a working plane. A tool diameter correcting means 107 derives a tool diameter correction vector Vs on the plane S. The vector Vs is a two-dimensional vector on the plane S, and can be derived simply. A coordinate transformation means 108 transforms the vector Vs on the plane S to a tool diameter correction vector V on the original coordinate system (X,Y,Z). By adding the vector V by an adder 109, a tool path L2 in which the tool diameter is corrected is derived. An interpolating means 110 derives a moving amount from this tool passage L2, and interpolates it. In such a way, the three-dimensional tool diameter correction can be executed simply.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a three-dimensional tool radius correction method for numerically controlled machine tools, and particularly relates to a three-dimensional tool radius correction method when machining a workpiece with a tilted tool. .

[Conventional technology]

In numerically controlled machine tools, the tool must be tilted relative to the workpiece in order to perform three-dimensional machining. These inclinations include those that incline the rotary head provided with the tool toward the work surface, and those that incline the work table.

Tool radius correction in a numerical control device is usually performed on a plane within a rectangular coordinate system. To perform three-dimensional tool radius correction, it is necessary to command the direction of the tool radius correction vector. In order to issue these commands, the direction of the tool radius correction vector must be known. For this reason, the following method is adopted for three-dimensional tool radius correction.

The first method is through automatic programming methods. According to the automatic programming method, when a cutting program is generated, a tool radius correction vector is also calculated at the same time, and a tool path with the tool radius corrected is automatically determined.

The second method is to convert the Canadian program to a specific plane, e.g. x
This is a method in which the tool path is created on the Y plane, the tool radius correction is also performed on this plane, and the coordinates are converted to an actual inclined plane.

[Problems to be Solved by the Invention] However, the first method using automatic programming always requires an automatic program creation device, making the system expensive. Furthermore, it is necessary to create a cutting program every time the tool diameter changes.

In addition, the second method is relatively useful when the machining plane is fixed, but when the machining plane changes, that is, when machining a curved surface, the tool path on the XY plane is , i.e., a transformation map that converts into a curved surface) IJ
coordinates change constantly, making coordinate transformation complicated. Therefore, an extremely heavy burden is placed on the processing of the numerical control device.

The present invention has been made in view of these points, and it is an object of the present invention to provide a three-dimensional tool radius correction method that allows easy tool radius correction in machining an inclined work surface.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a three-dimensional tool radius correction method for a numerically controlled machine tool in which a workpiece is machined by tilting the tool in three-dimensional space. vector calculation means for calculating a tool direction vector from the position; plane calculation means for calculating an offset plane perpendicular to the tool direction vector from the tool direction vector; and calculating a first tool radius vector on the offset plane. a tool radius correction means; a coordinate conversion means for converting the first tool radius correction vector into a second tool correction vector on the original coordinate system;
A three-dimensional tool radius correction method is provided, comprising: an adder that adds a tool radius correction vector to obtain a tool path; and an interpolation means that interpolates the tool path.

[Effect]

The vector calculation means calculates the inclination of the tool, that is, the tool direction vector, from the position information of the axis that controls the inclination of the tool. For example, when the inclination of the tool is controlled by the rotary head and the tilt of the rotary head is controlled by the B-axis and the C-axis, the tool direction vector is determined from the current positions of the B-axis and the C-axis.

Next, the plane calculation means calculates an offset plane perpendicular to the tool direction vector from the tool direction vector. In other words, this offset plane is also a processing plane. The tool radius correction means obtains a first tool radius correction vector on this offset plane. This first tool radius correction vector is a two-dimensional vector on the offset plane, and can be obtained relatively easily.

The coordinate conversion means converts the first tool radius correction vector on the offset plane into a second tool radius correction vector in the original coordinate system. The second tool radius correction vector is a three-dimensional tool radius correction vector.

By adding this second tool radius correction vector to the program path, the final tool path is determined, and the interpolation means interpolates this tool path.

〔Example〕 Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 2 is a general view of the rotary head for tilting the tool. The rotary head 1 can rotate around an axis 3 parallel to the Y axis. This axis of rotation is designated as the B axis. It can also rotate around an axis 4 parallel to the Z axis, and this rotation axis is referred to as the C axis. A tool 5 is provided at the tip of the shaft 4.

Therefore, the tool 5 can be tilted at any angle as the B-axis and C-axis are rotated, and a workpiece plane having any tilt can be machined. On the other hand, by calculating and providing a tool correction vector according to the inclination of the tool 5, a workpiece having an arbitrary inclined machining surface can be machined.

On the other hand, when the tool 5 is tilted, the tool diameter correction must be performed on the tilted surface. Therefore, three-dimensional tool radius correction is required.

Next, the three-dimensional tool radius correction method will be described. FIG. 3 is a diagram for explaining the outline of the three-dimensional tool radius correction method of the present invention. Tool 5 is in the coordinate system (X, Y.

2) is perpendicular to the offset plane S inclined with respect to 2). The program path on the cutting program is Ll, and the tool path after tool radius correction obtained by performing tool radius correction is L2.

First, the numerical control device can determine the tool direction vector Vt of this tool 5 from the current positions of the B-axis and C-axis.

Further, an offset plane S perpendicular to this tool direction vector Vt can be calculated. Here, the coordinate system on the offset plane S is assumed to be (Xs, Ys, Zs).

Next, a path obtained by projecting the program path L1 onto the offset plane S is assumed to be Lls, and a path obtained by projecting the tool path L2 after tool radius correction onto the offset plane S is assumed to be L2s. Since the offset plane S has been determined, a tool radius correction vector Vs that is perpendicular to the path Lls and has a size equal to the tool radius r can be determined. Here, since the tool radius correction vector Vs is a two-dimensional vector on the offset plane S, it can be obtained relatively easily.

This tool radius correction vector Vs is the same as the tool radius correction vector V that corrects the tool radius from the program path L1 to the tool path L2. Therefore, by adding the tool radius correction vector Vs to the program path L1, the tool path L2 can be determined. In other words, three-dimensional tool radius correction becomes possible.

However, since the tool radius correction vector Vs is found in the coordinate system (Xs, Ys, Zs) on the offset plane S,
It is necessary to return to the original coordinate system (X, Y, Z). This conversion matrix can be obtained from the tool direction vector Vt. As a result, if the tool radius correction vector V is added to the program path L1, the tool path L with the tool radius
2 is required.

FIG. 1 is a block diagram of the three-dimensional tool radius correction method of the present invention. Processing of each of these blocks is executed by software of the numerical control device, which will be described later. The preprocessing calculation means 102 reads the cutting program 101, sends a movement command to the adder 109, and when there is a tool radius correction command, sends the tool radius correction command to each block described later.

The vector calculation means 105 stores the current position of the B axis and the current position of the C axis that control the rotary head 2 in the register 103.
is read from the register 104, and the tool direction vector Vt of the tool 5 is determined.

Next, the plane calculation means 106 calculates an offset plane S perpendicular to the tool direction vector Vt from the tool direction vector ˜t. This offset plane S is also a machining plane in other words. A tool radius correction vector Vs is determined on the offset plane S. This tool radius correction vector S is a two-dimensional vector on the offset plane S, and can be determined relatively easily.

The coordinate conversion means 108 transforms the tool radius correction vector Vs on this offset plane S into the original coordinate system (X, Y.

Z) is converted into the tool radius correction vector V above. The tool radius correction vector V is a three-dimensional tool radius correction vector.

If this tool radius correction vector V is added to the program path L1 by the adder 109, the tool path L2 with the tool radius corrected is
is found. The interpolation means 110 determines the amount of movement from this tool path L2 and interpolates it.

The interpolated distribution pulse is accelerated or decelerated by the acceleration/deceleration control means 111 and sent to the axis control circuit 41. The axis control circuit 41 converts the distribution pulse into a speed control signal and sends it to the servo amplifier 51. Servo amplifier 51 amplifies the speed control signal and drives servo motor 61. The servo motor 61 has a built-in pulse coder for position detection, and the axis control circuit 41
Feed back the position feedback pulse to.

In FIG. 1, the acceleration/deceleration control means 111, the axis control circuit 41, the servo amplifier 51, and the servo motor 61 are shown for only one axis. Actually, five axes are required, but since the elements of the other axes are the same, they are omitted.

FIG. 4 is a flowchart of the processing of the three-dimensional tool radius correction method. In the figure, the number following S indicates the step number.

[S1] The preprocessing calculation means 102 uses the Kani program 101
It is determined whether there is a command to start three-dimensional tool radius correction, and if there is, the process advances to S2; if not, the process advances to S3.

[S2] Since there is a start-up command, start-up processing is performed. That is, the first offset vector is generated, etc.

[S3] Determine whether there is a command to cancel three-dimensional tool radius correction, and if so, proceed to S4; if not, proceed to S5.

[S4] Since there is a three-dimensional tool radius correction cancellation command, the offset vector is canceled.

[35] Determine whether the three-dimensional tool radius correction mode is in progress. If the mode is the three-dimensional tool radius correction mode, proceed to S6; otherwise, proceed to 510.

[S6] Vector calculation means 105 registers 103 and 1
04, the current positions of the B-axis and C-axis are read, and the tool direction vector Vt is calculated.

[S7] The plane calculating means 106 calculates an offset plane S having the tool direction vector Vt as a normal line from the tool direction vector Vt.

[S8] The tool radius correction means 107 determines the tool radius correction vector Vs for the program path Lls projected onto the offset plane S.

[S9] The coordinate conversion means 108 converts the tool radius correction vector Vs
The tool radius correction vector V in the original coordinate system is obtained by converting the coordinates of
seek.

[310] Adder 109 adds program path L1
The tool path L2 is obtained by adding the tool radius correction vector V to

[S11] The interrogation means 110 obtains the movement amount from the tool path L2, interpolates this, and outputs a distribution pulse.

FIG. 5 shows a numerical control device (CNC) for implementing the present invention.
) is a block diagram of the hardware.

In the figure, 10 is a numerical control device (CNNC). The processor 11 is a central processor for controlling the entire numerical control device (CNC) 10, reads out a system program stored in the ROM 12 via the bus 21, and executes the numerical control bag W according to this system program.
(CNC) Executes overall I/O control. The RAM 13 stores temporary calculation data, display data, etc. R
SRAM is used for AM13. The CNC 314 stores tool diameter correction amounts, pitch error correction amounts, cutting nib programs, parameters, and the like.

The CNC 314 is backed up by a battery (not shown) and is a non-volatile memory even when the power of the numerical control device (CNC) 10 is turned off, so its data is retained as is.

The interface 15 is an interface for external equipment, and external equipment 31 such as a paper tape reader, paper tape puncher, paper cheap reader/puncher, etc. is connected thereto. A cannibal program is read from a paper tape reader, and a cannibal program edited in a numerical control device (CNC) 10 can be output to a paper tape puncher.

PMC (Programmable Machine Controller) 16
is built into the CNC 10 and controls the machine using a sequence program created in ladder format. That is, according to the M function, SR function, and T function commanded by the machine program, these are converted into necessary signals on the machine side using a sequence program, and the signals are output from the I10 unit 17 to the machine side. This output signal drives a magnet, etc. on the machine side, and operates a hydraulic valve, a pneumatic valve, an electric actuator, etc. It also receives signals from limit switches on the machine side, switches on the machine operation panel, etc., performs necessary processing, and passes them to the processor 11.

Image signals such as the current position of each axis, alarms, parameters, and image data are sent to the display device of the CRT/MDI unit 25 and displayed on the display device.

The interface 19 receives data from the keyboard in the CRT/MDI unit 25 and passes it to the processor 11.

Interface 20 is connected to and receives pulses from manual pulse generator 32 . A manual pulse generator 32 is mounted on the machine operation panel and is used to manually precisely position the machine moving parts.

Axis control circuits 41 to 45 receive movement commands for each axis from the processor 11 and send commands for each axis to servo amplifiers 51 to 55.
Output to. Servo amplifiers 51-55 receive this movement command and drive servo motors 61-65 for each axis. The servo motors 61 to 65 have a built-in pulse coder for position detection, and a position signal is fed back from the pulse coder as a pulse train. In some cases, a linear scale is used as a position detector.

Further, by performing F/V (frequency/velocity) conversion on this pulse train, a velocity signal can be generated. In the figure, these position signal feedback lines and velocity feedback are omitted.

The spindle control circuit 71 receives a spindle rotation command, a spindle orientation command, etc., and outputs a spindle speed signal to the spindle amplifier 72. The spindle amplifier 72 receives this spindle speed signal and
The spindle motor 73 is rotated at the commanded rotation speed. Further, the spindle is positioned at a predetermined position by an orientation command.

A position coder 82 is connected to the spindle motor 73 by a gear or a belt. Therefore, the position coder 82 rotates in synchronization with the spindle 73 and outputs a feedback pulse, which is read by the processor 11 via the interface 81. This feedback pulse causes the other axes to move in synchronization with the spindle motor 73, enabling precise tapping and the like.

In the above description, the inclination of the tool is controlled by controlling the rotary head, but it is also possible to incline the table and incline the tool relative to the work surface. In this case, the tool radius correction vector is calculated from the current position of the axis that controls the table.

Further, although the two axes are used to control the inclination of the tool, the invention can be similarly applied to the case where the inclination of the tool is controlled by the l-axis.

〔Effect of the invention〕

As explained above, in the present invention, when the tool is tilt-controlled, the tool radius correction vector is obtained on the offset plane, converted to the original coordinate system, and the tool radius correction is performed. Three-dimensional tool radius correction can be performed. As a result, an automatic program creation device or the like is not required. Further, since calculations can be easily performed, the burden on the numerical control device is reduced.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the three-dimensional tool radius correction method of the present invention, Fig. 2 is an overview of the rotary head for tilting the tool, and Fig. 3 outlines the three-dimensional tool radius correction method of the present invention. Figure 4 is a flowchart of the processing of the three-dimensional tool radius correction method, and Figure 5 is a numerical control device (CNC) for implementing the present invention.
) is a block diagram of the hardware. 41 to 45 51 to 55 61 to 65 0-Clean head tool processor OM AM MOS Axis control circuit Servo amplifier Servo motor Machining program Preprocessing calculation means Register Register Vector calculation means Plane calculation means

Claims (4)

[Claims] (1) In a three-dimensional tool radius correction method for numerically controlled machine tools in which a workpiece is machined by tilting the tool in three-dimensional space, the tool direction vector is calculated from the current position of the control axis that controls the tilt of the tool. a plane calculation means for calculating an offset plane perpendicular to the tool direction vector from the tool direction vector; a tool radius correction means for calculating a first tool radius vector on the offset plane; a coordinate conversion means for converting a first tool radius correction vector into a second tool correction vector on the original coordinate system; an adder that adds the second tool radius correction vector to a program path to obtain a tool path; and the tool A three-dimensional tool diameter correction method comprising: interpolation means for interpolating a path; (2) The three-dimensional tool radius correction method according to claim 1, wherein the mechanism for controlling the inclination of the tool is a rotary head. (3) The axes that control the rotary head are the B-axis and the C-axis, and the vector calculation means calculates the tool direction vector from the current positions of the B-axis and the C-axis. 3-dimensional tool diameter correction method described in 2. (4) The three-dimensional tool radius correction method according to claim 1, wherein the mechanism for controlling the inclination of the tool is a rotary table.