JPH0474205A - Correction system for tool diameter - Google Patents

Abstract

PURPOSE:To omit an automatic program producing device, etc., by obtaining a tool diameter correcting vector with a numerical controller when a machining is carried out at the edge of a tool after tilting the tool. CONSTITUTION:A vector calculation means calculates a tool directional vector from the position information on the axis that controls the tilt of a tool. When the tilt of a rotary head 1 is controlled by axes B and C, for example, the tool directional vector is obtained from the present positions of both axes B and C. A plane arithmetic means 106 operates an offset plane vertical to the vector based on the tool directional vector. At the same time, a traveling direction calculation means 108 calculates the traveling direction of the tool. A tool diameter correction vector arithmetic means 107 generates a tool diameter correction vector having a size equal to the tool radius on a straight line produced from the cross between a plane and a surface formed between the tool directional vector and the tool traveling direction. Then the tool diameter correction vector is applied to a program path so that the final tool path is obtained. This tool path is interpolated by an interpolation means 110. Thus the edge machining is simplified for a tilted tool.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a tool diameter correction method in a numerically controlled machine tool.
In particular, the present invention relates to a 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.

On the other hand, in three-dimensional machining, the tool may be tilted and machining may be performed at the edge of the tool. For this purpose, it is necessary to obtain the tool radius correction vector as a three-dimensional vector. There are the following methods to obtain a three-dimensional tool radius correction vector.

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.
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.

[Problem to be solved by the invention]

However, the first method using automatic programming always requires automatic programming equipment, 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 In other words, the transformation matrix for converting into a curved surface constantly changes, making the 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 tool radius correction method that can easily perform tool radius correction when machining a workpiece with the edge of the tool by tilting the tool. purpose.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a control axis that controls the inclination of the tool in a tool radius correction method for a numerically controlled machine tool in which the tool is tilted in three-dimensional space and a workpiece is machined with the edge of the tool. A vector calculation means for calculating a tool direction vector from the current position of the tool, a plane calculation means for calculating an offset plane perpendicular to the tool direction vector from the tool direction vector, and a preprocessing calculation means. a traveling direction calculation means for calculating a traveling direction;
a tool radius correction vector calculating means for generating a tool radius correction vector having a size equal to the tool radius on a straight line formed by intersecting the plane and a plane formed by the tool direction vector and the traveling direction of the tool; A tool radius correction method is provided, comprising: an adder that adds the tool radius correction vector to a program path 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 a rotary head and the inclination of the rotary head is controlled by the B-axis and the C-axis, the tool direction vector is calculated 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. Further, the traveling direction calculation means calculates the traveling direction of the tool.

The tool radius correction vector calculation means generates a tool radius correction vector having a size equal to the tool radius on a straight line formed by intersecting a plane formed by the tool direction vector and the tool advancing direction.

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

This makes it possible to easily perform edge machining with an inclined tool.

〔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 with the rotation of the B-axis and the C-axis.
Processing can be performed with the edges of For this purpose, it is necessary to calculate and provide a tool radius correction vector according to the inclination of the tool 5.

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, a tool radius correction method for performing machining using the edge of the tool 5 will be described. FIG. 3 is a diagram for explaining the outline of the tool radius correction method of the present invention. The tool 5 is tilted with respect to the workpiece 7, and the edge 6 of the tool 5 touches the workpiece 7.
Process the surface of.

The program path Lp is on the surface 8 of the workpiece 7.

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.

Also, a plane S perpendicular to this tool direction vector Vt (in the figure, the plane S is represented by a straight line because it is perpendicular to the plane of the paper)
can be calculated. On the other hand, the tool advancing direction Td is the same direction as the program path Lp.

Here, a tool radius correction vector (■) is generated on a line where the plane S intersects the plane formed by the tool axis direction vector Vt and the tool advancing direction Td (the plane of the drawing).

The magnitude of the tool radius correction vector V is the radius of the tool 6.

If tool radius correction is performed on the program path Lp using the tool radius correction vector V, the tool path Lt, which is the center path of the tool 6, is obtained. By interpolating this tool path Lt, the workpiece 7 can be machined with the edge 6 of the tool 5.

FIG. 1 is a block diagram of a tool radius correction method when machining is performed at the edge of a tool according to 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 below. The vector calculation means 105 is the rotary head 2
The current position of the B-axis, which controls the B-axis, is read from the register 103, and the current position of the C-axis 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 a plane S perpendicular to the tool direction vector Vt from the tool direction vector Vt. Further, the traveling direction calculation means 108 reads the movement command from the preprocessing calculation means 102 and calculates the traveling direction Td of the tool 5.

The tool radius correction vector calculating means 107 calculates a plane formed by the tool direction vector Vt and the tool advancing direction Td. This plane is the plane of the paper in FIG. Next, find a line where this surface and plane S intersect. A tool radius correction vector V whose direction is on this line and whose size is the radius of the tool 5 is determined.

Adder 109 adds tool radius correction vector V to program path Lp to determine tool path Lt.

The interpolation means 110 calculates the amount of movement from this tool path Lt,
Interpolate this.

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 processing of the 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 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 tool radius correction vector is generated.

[S3] Determine whether there is a command to cancel tool diameter correction,
If so, proceed to S4; if not, proceed to S5.

[S4] Since there is a command to cancel the tool radius correction, the tool radius correction vector is canceled.

[S5] Determine whether the tool radius correction mode is in progress. If the tool radius correction mode is selected, proceed to S6; otherwise, proceed to S10.

[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 a plane S having the tool direction vector Vt as a normal line from the tool direction vector Vt.

[88 traveling direction calculation means 108 calculates the traveling direction T of the tool 5
Find d.

[S9] The tool radius correction vector calculating means 107 calculates a plane consisting of the tool direction vector Vt and the tool advancing direction Td. A tool radius correction vector V, which lies on a line formed by the intersection of this surface and the plane S and whose size is the radius of the tool 5, is determined.

[S10] The adder 109 adds the program path Lp
The tool path Lt is calculated by adding the tool radius correction vector V to .

[S11] The interrogation means 110 determines the amount of movement from the tool path Lt, 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 (CNC). The processor 11 is a processor that plays a central role in controlling the entire numerical control device (CNC) 10.
Reads the system program stored in OM12,
According to this system program, the numerical control device (CN)
C) Execute overall control of 10. The RAM 13 stores temporary calculation data, display data, etc. RAM13
SRAM is used for this. The CMO 314 stores tool diameter correction amounts, pitch error correction amounts, cutting nib programs, parameters, and the like.

The CMO 514 is backed up by a battery (not shown) and serves as a non-volatile memory even when the power of the numerical control unit (CNC) 10 is turned off, so its data is retained as is.

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

PMC (7” programmable machine controller) 1
6 is built into the CNCl0 and controls the machine using a sequence program created in ladder format. That is, according to the M function, S 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 the magnet etc. on the machine side,
Operate hydraulic valves, pneumatic valves, electric actuators, etc. In addition, it receives signals from limit switches on the machine side, switches on the machine operation panel, etc., and performs the necessary processing.
It is passed 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 inclination of the tool is controlled by two axes, the present invention can be similarly applied to the case where the inclination of the tool is controlled by one axis.

Figure 4 is a flowchart of the processing of the tool radius correction method, Figure 5 is a numerical control device (CNC) for carrying out the present invention.
) is a block diagram of the hardware.

[Effects of the Invention] As explained above, in the present invention, when the tool is tilted and machining is performed at the edge of the tool, the tool diameter correction vector is determined within the numerical control device. This allows machining at the edge of the tool. As a result, a zero-recommendation program creation device or the like is not required.

[Brief explanation of the drawing]

Figure 1 is a block diagram of the tool radius correction method when machining is performed at the edge of the tool of the present invention, Figure 2 is an overview of the rotary head that tilts the tool, and Figure 3 is the tool radius compensation method of the present invention. Explain the outline of 1
Rotary head 5 Tool 11 Processor 12 ROM 13 RAM 14 0M OS 41-45 Axis control circuit 51-55 Servo amplifier 61-65 Servo motor 101 Niprogram 102-° pre-processing calculation means 103... °Current position register 104- ---Current position register 105--Vector calculation means Plane calculation means Tool radius correction vector calculation means Traveling direction calculation means Adder Interpolation means Acceleration/deceleration control means

Claims (4)

[Claims] (1) In the tool radius correction method for numerically controlled machine tools in which the tool is tilted in three-dimensional space and the workpiece is machined with the edge of the tool, the tool direction vector is calculated from the current position of the control axis that controls the tool tilt. a plane calculation means for calculating an offset plane perpendicular to the tool direction vector from the tool direction vector; and a travel direction calculation for calculating the tool travel direction based on a command from the preprocessing calculation means. means, a tool radius correction vector for generating a tool radius correction vector having a size equal to the tool radius on a straight line formed by intersecting the plane and a plane formed by the tool direction vector and the traveling direction of the tool; A tool radius correction method comprising: an arithmetic unit; an adder that adds the tool radius correction vector to a program path to obtain a tool path; and an interpolation unit that interpolates the tool path. (2) The 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. Tool radius correction method described in 2. (4) The tool radius correction method according to claim 1, wherein the mechanism for controlling the inclination of the tool is a rotary table.