JPH06143093A - Abrasion correction method - Google Patents

Abstract

PURPOSE:To enable the offset amount of a tool due to abrasion to be corrected at all times. CONSTITUTION:The used time of a tool is measured by a clock means 1, and the abrasion loss of the tool is estimated by an abrasion loss estimating means 4 at all times in response to measured time, so that the offset amount OSFc of the tool after correction is obtained, and concurrently each correction command ever distribution pulse is prepared with the offset amount OFSc of the tool processed. The aforesaid correction process is execuated even while the block of a process program 6 is being executed. A pre-process operating means 6 prepares a move command using read program data, it sends the command to an interpolation means 7, and interpolation is performed by the interpolation means 7, so that the distribution pulse is then outputted to a distribution correction means 9. The distribution correction means 9 then allows a correction command to be added to the distribution pulse from the interpolation means 7, so that the tool is controlled to be moved by means of the aforesaid corrected distribution pulse. By this constitution, even at the time of processing within the block of a processing program, the abrasion loss of the tool can be corrected at all times, so that a work can thereby be machined with high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool wear compensation system used in a machine tool controlled by a numerical controller, and more particularly to a tool for constantly estimating the wear amount of the tool and appropriately compensating for the tool offset amount. Of the wear correction method.

[0002]

2. Description of the Related Art Generally, a numerical control device calculates a path of a tool reference point which is separated from a work by a tool offset amount with respect to a machining path specified by a machining program, and feeds the tool along the path of the tool reference point. Control is performed.
The tool offset amount is the length from the tool reference point to the tool tip (tool length) for cutting tools and the like, and the radius (tool diameter) from the rotation axis to the outer circumference for milling tools and the like.

On the other hand, the tool is worn by being used for machining, but if the reduction of the tool offset amount due to this wear is left unchecked, the route of the tool reference point becomes improper and the machining can be carried out as instructed. Disappear. That is, the processing accuracy deteriorates.

Therefore, conventionally, the tool offset amount is actually measured before machining, and the measured value is set in the numerical controller, and the numerical controller calculates the route of the tool reference point based on the measured value. Was there.

[0005]

However, measuring the tool offset amount each time the machining is started and setting the measured value in the numerical controller causes a problem that workability is impaired. Also, depending on the type of machining, once machining is started, the machining time may take several hours. In this case, the tool will be worn too much by the time of the next actual measurement of the tool offset amount, which will adversely affect the machining accuracy. There was a possibility that it would be too big.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a tool wear correction system capable of always correcting the tool offset amount due to wear without impairing workability. To do.

[0007]

In order to solve the above-mentioned problems, the present invention provides a means for measuring the tool usage time in a tool wear compensation system used in a machine tool controlled by a numerical controller. A wear amount estimating means for estimating the wear amount of the tool according to the time measured by the time measuring means, and a correction for correcting the distribution pulse for the movement of the tool using the wear amount estimated by the wear amount estimating means And a tool wear correction method characterized by having
Provided.

[0008]

The operation time of the tool is measured, and the wear amount of the tool is constantly estimated according to the measured time. The estimated wear is used to correct the dispense pulse for tool movement.

Therefore, the amount of wear of the tool can be constantly corrected even during machining within the block of the machining program. Therefore, it is possible to perform highly accurate machining without causing machining shortage due to wear of the tool.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a numerical controller (CN) to which the present invention is applied.
It is a block diagram of hardware of C). In the figure,
Reference numeral 10 is a numerical controller (CNC). Processor 11
Is a processor that is the center of control of the entire CNC 10, reads the system program stored in the ROM 12 via the bus 21, and executes the control of the entire CNC 10 in accordance with this system program. The RAM 13 stores temporary calculation data, display data, and the like. R
SRAM is used for AM13. Non-volatile memory 1
Reference numeral 4 denotes a CMOS, which stores a table 3, which will be described later, a machining program, parameters and the like. The nonvolatile memory 14 is backed up by a battery (not shown), and even if the power of the CNC 10 is turned off, those data are retained as they are.

The interface 15 is an interface for an external device, and is connected to an external device 31 such as a paper tape reader, a paper tape puncher, and a paper tape reader / puncher. The processing program is read from the paper tape reader, and the processing program edited in the CNC 10 can be output to the paper tape puncher.

A PMC (Programmable Machine Controller) 16 is built in the CNC 10 and controls a machine tool by a sequence program created in a ladder format. That is, the M function instructed by the machining program,
According to the S function and the T function, these are converted into necessary signals on the machine side by the sequence program and output from the I / O unit 17 to the machine side. This output signal drives a magnet or the like on the machine side to operate a hydraulic valve, a pneumatic valve, an electric actuator, or the like. In addition, receiving signals from the machine side limit switch and machine operation panel switch,
The necessary processing is performed and it is passed to the processor 11.

The current position of each axis, alarms, parameters,
Image signals such as image data are sent to the CRT / MDI unit 26
Is sent to the display device and displayed on the display device. The interface 19 receives the data from the keyboard in the CRT / MDI unit 26 and transfers it to the processor 11.

The interface 20 is a manual pulse generator 3
2 and receives the pulse from the manual pulse generator 32. The manual pulse generator 32 is mounted on the machine operation panel,
Used to precisely position machine working parts manually.

The axis control circuits 41 to 45 receive the movement command of each axis from the processor 11 and output the command of each axis to the servo amplifiers 51 to 55. The servo amplifiers 51 to 55 receive the movement command and drive the servo motors 61 to 65 of the respective axes. The servo motors 61 to 65 have a built-in pulse coder for position detection, and the position signal is fed back from this pulse coder as a pulse train. In some cases, a linear scale is used as the position detector. Further, a speed signal can be generated by F / V (frequency / speed) conversion of this pulse train.
In the figure, the feedback line and velocity feedback of these position signals are omitted.

The spindle control circuit 71 outputs a spindle speed signal to a spindle amplifier 72 in response to a spindle rotation command and a spindle orientation command. The spindle amplifier 72 receives the spindle speed signal and rotates the spindle motor 73 at the commanded rotation speed. In addition, the spindle is positioned at a predetermined position according to the 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, outputs a feedback pulse, and the feedback pulse is read by the processor 11 via the interface 81. This feedback pulse moves the other shaft in synchronization with the spindle motor 73, enabling precise tapping processing and the like.

A procedure of tool wear correction according to the present invention, which is carried out by the numerical controller having the above-mentioned structure, will be described below with reference to FIG. FIG. 1 is a block diagram showing a procedure of tool wear correction performed by the CNC 10. The time measuring means 1 starts measuring the elapsed time from the processing start time immediately after the latest measured value of the tool offset amount is set, and outputs the elapsed time to the wear amount estimating means 4. The machining condition reading means 2 reads the machining conditions such as the material of the work, the spindle rotation speed, and the tool feed speed from the parameters preset in the CNC 10 and the machining program 5, and outputs them to the wear amount estimating means 4. In Table 3, data of the amount of wear OFS _W of the tool, which is experimentally obtained, is stored in advance in the nonvolatile memory 14, and an example thereof is shown in FIG. That is, as shown in FIG. 4, the wear amount OFS _W increases as the elapsed time increases, as the as the material of the workpiece is hardened, or the spindle speed increases, more tool feed speed increases Along with this, the line L1 changes to a line L2 and a line Ln.

The wear amount estimating means 4 selects a straight line from the straight lines L1, L2 and Ln of the table 3 according to the material of the work, the spindle speed and the tool feed speed,
It reads the tool wear amount OFS _W corresponding to the elapsed time based on the picked out linearity, the wear amount on the basis of the OFS _W, and outputs the corrected tool offset amount OFS is measured value that has been set as a parameter. That is,
Tool offset amount O after correction of the tool offset amount value obtained by subtracting the wear amount OFS _W from OFS (OFS-OFS _W)
FS _G is set, and the corrected tool offset amount OFS _G is processed to create a correction command for each distributed pulse. This correction process is always performed even while the block of the machining program is being executed.

The preprocessing calculation means 6 reads the machining program 5, performs preprocessing using the read data to create a movement command, and sends it to the interpolation means 7. The interpolation means 7 performs interpolation and outputs the distribution pulse to the distribution correction means 9.

The distribution correction means 9 adds the correction command from the wear amount estimation means 4 to the distribution pulse from the interpolation means 7, and sends the corrected distribution pulse to the acceleration / deceleration control means 8. The corrected distribution pulse is further accelerated / decelerated by the acceleration / deceleration control means 8 and sent to the axis control circuit 41. Axis control circuit 4
1 converts the distributed pulse into a speed control signal and sends it to the servo amplifier 51. The servo amplifier 51 amplifies the speed control signal and drives the servo motor 61. As described above, the servo motor 61 has a pulse coder for position detection built therein, and feeds back the position feedback pulse to the axis control circuit 41.

In FIG. 1, acceleration / deceleration control means 8 and axis control circuit 4 are shown.
1, the servo amplifier 51, and the servo motor 61 represent only one axis. Actually, five axes are required, but the elements of the other axes are the same as the above-mentioned elements, so the illustration thereof is omitted.

FIG. 3 shows a tool offset amount O which is a measured value.
FS, tool wear amount OFS _W, is a diagram showing the relationship of the tool offset amount OFS _G corrected, 3 (A) shows a cutting tool, FIG. 3 (B) shows a milling tool. R is a tool reference point. Figure, found in a tool offset amount OFS from the value obtained by subtracting the tool wear amount OFS _W (OFS-OFS _W) is, tool offset amount O after correction
It is FS _G. The tool offset amount OFS _G after correction is calculated in exactly the same procedure for the cutting tool and the milling tool.

Next, an actual tool wear correction example will be described with reference to FIGS. FIG. 5 is a diagram showing a processing route.
In the figure, the tool is a block N1 of the machining program,
According to N2, N3, N4, N5, the starting point O to P1 point,
It returns to the point P1 via the points P2, P3 and P4. An example of the machining program at this time is shown below.

O0001; ..... N1 G90 G00 X500. Y500. N2 G42.2 G01 X1000. F100 L
1; N3 Y1000. F500 L2; N4 X500. F200 L3; N5 Y500. F500 L4; ... In the above machining program "O0001", G42.2: Tool wear correction code according to the present invention L1, L2, L3, L4: Each straight line of table 3 in the non-volatile memory 14 Is. In this machining program "O0001", the table 3 is used to estimate the wear amount according to the change in machining conditions.
The respective straight lines stored in are changed to L1 to L4 to correspond. That is, the block N2 is based on the straight line L1, and the block N3 is based on the straight line L2.
4 is based on the straight line L3, and in block N5 is the straight line L4.
Based on the above, the tool wear amount is corrected. An example of wear amount correction at this time is shown in FIG.

FIG. 6 is a view showing an example of tool wear amount correction. In the figure, the horizontal axis represents the processing time T, the vertical axis represents the tool wear amount OFS _W estimated on the basis of the data of table 3. Tool wear amount OFS _W is integrated with the processing time T, the tool wear amount OFS _W at the time of the block N5, block N2, N3, block the total amount of wear on the N4 N
The wear amount at 5 is added. The tool wear amount O
The tool center path when corrected based on FS _W is shown in FIG.

FIG. 7 is a diagram showing a tool center path during machining in one block. As shown in the figure, it is assumed that the tool 100 is worn down to the state of the tool 100A when machining one block. When the wear amount of the tool 100 is not corrected, the path is machined along the tool center path 101, and the machined surface 102 at that time has an unmachined portion with respect to the target machined surface 120. As a result, insufficient processing δ occurs. On the other hand, in the present embodiment, even if the machining is continued for a long time within one block, the correction is performed for each distributed pulse, so that the wear amount is constantly corrected. Therefore, even if the tool 100 is worn, insufficient machining δ does not occur, and it is possible to perform machining along the target machining surface 120. Therefore, it is possible to perform highly accurate machining without causing machining shortage due to wear of the tool.

In the above embodiment, the wear amount is corrected by the program command, but the wear amount is corrected according to the external signal, for example, the command signal from the PMC or the ON signal of the operation panel switch. You can also do it.

Further, in the above embodiment, includes a table 3, the wear amount estimation means 4, but reads the tool wear amount OFS _W from the table 3 depending on how old the processing conditions and tools, other As an example, the table may not be used. That is, the wear amount estimating means 4
But has a function of tool wear amount OFS _W which is determined according to the elapsed time of the machining conditions and the tool, it calculates the tool wear amount OFS _W using the function. The above function is a linear function having the elapsed time of use of the tool as a variable, and a plurality of its coefficients are prepared so that the coefficient can be selected according to the processing conditions.

Further, in the above two embodiments, tool wear
Quantity OFS_WEach straight line L of Table 3 when determining
Select one from 1, L2 and Ln according to the processing conditions.
Or one of multiple coefficients according to the processing conditions
However, as another example,
There is also a method of not making the selected selection. That is, in general, tools
Is because it is selected according to the processing conditions.
The range of processing conditions in which one tool can be used is narrow,
The machining conditions of the tool have already been decided to some extent. According to
A certain tool wear amount OFS_WFor the table
It is also said that the straight line of
Get For these reasons, the tool wear amount OFS _WThis
At the stage, without considering the processing conditions, simply when the tool is in use
Tool wear amount O with relatively little error, even if determined only by
FS_WCan be estimated. Considering such points, the tool wear amount O
FS_WIs determined based only on the elapsed time of use of the tool,
The numerical controller may have a simple structure.

[0031]

As described above, according to the present invention, the tool usage time is measured, the wear amount of the tool is constantly estimated according to the measured time, and the distribution pulse for the movement of the tool is calculated using the estimated wear amount. It is configured to correct.

Therefore, the amount of wear of the tool can be constantly corrected even during long-time continuous machining within the block of the machining program. Therefore, it is possible to perform highly accurate machining without causing machining shortage due to wear of the tool.

Further, since the correction is always carried out, it is possible to save the trouble of exchanging tools and measuring the tools, and to shorten the machining cycle time accordingly.

[Brief description of drawings]

FIG. 1 is a block diagram showing a procedure of tool wear correction performed by a CNC.

FIG. 2 is a block diagram of hardware of a numerical control device (CNC) to which the present invention is applied.

[Figure 3] tool offset amount OFS, which is measured values, the tool wear amount OFS _W, a diagram representing the relationship between the tool offset amount OFS _G corrected, (A) shows the cutting tool,
(B) shows a milling tool.

4 is a diagram showing a table of tool wear amount OFS _W.

FIG. 5 is a diagram showing a machining path.

FIG. 6 is a diagram showing an example of tool wear amount correction.

FIG. 7 is a diagram showing a tool center path during machining in one block.

[Explanation of symbols]

 1 Timekeeping means 2 Machining condition reading means 3 Table 4 Wear amount estimating means 5 Machining program 7 Interpolating means 9 Distribution correcting means

Claims (2)

[Claims] 1. A tool wear compensation system used in a machine tool controlled by a numerical control device, comprising: a time measuring means for measuring a use time of the tool; and a tool of the tool according to the time measured by the time measuring means. A wear correction method for a tool, comprising: a wear amount estimating means for estimating a wear amount; and a correcting means for correcting a distribution pulse for the movement of the tool using the wear amount estimated by the wear amount estimating means. . 2. The use time of the tool under various processing conditions and the wear amount of the tool are registered in advance in the numerical controller as data for estimating the wear amount of the tool, and the wear amount estimating means is configured to 2. The tool wear correction method according to claim 1, wherein the wear amount of the tool is estimated by referring to the registered data based on the usage time of the tool measured by the time measuring means.