JP4236483B2 - Machine tools with tool wear compensation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a machining method for machining in consideration of the amount of tool wear, and a machine tool having a tool wear correction function.
[0002]
[Prior art]
In an NC machine tool, a workpiece is machined by relatively moving a tool mounted on a spindle and a workpiece placed on a table according to a desired machining program. Therefore, the shape of the workpiece obtained by machining depends on the movement trajectory of the tool. Will be determined. Generally, the machining program is created on the assumption that the tool is not worn by machining and the tool length is constant.
[0003]
[Problems to be solved by the invention]
However, in reality, the tool wears with machining, and the tool length is gradually shortened. For example, as shown in FIG. In the case of a surface, the actual machining shape 43 gradually rises upward from the desired machining shape 41, and shifts occur. Therefore, the desired processed shape 41 cannot be obtained.
[0004]
Further, when the tool is worn, the tool life is detected and the tool is changed by a method described in JP-A-54-35485, JP-A-2001-150299, or the like. For this purpose, the machining is interrupted and the worn tool is replaced with a new tool having a standard length, and then the machining is resumed. However, in this case, since the tool after replacement is not worn, when the tool is returned to the command position according to the machining program, the actual tool edge position is lowered by the amount of wear of the tool before replacement before and after tool replacement. It will shift. Also, when the machining of the first area is interrupted by using the same tool and the machining of the first area is resumed after the machining of the second area different from the first area, Since the amount of wear of the tool has changed before and after the machining interruption related to the area, similarly, if the tool is returned to the command position when machining was interrupted, the actual tool edge position will change before and after the machining interruption. Become. As a result, a step 45 (see FIG. 5) is generated in the machining shape before and after machining interruption for tool change or machining in a different area, resulting in inconvenience. In FIG. 5, since the tool change was performed three times, three steps 45 appear in the processed shape.
[0005]
Therefore, an object of the present invention is to solve the problems existing in the above-mentioned prior art caused by tool wear and to obtain a machining shape with little deviation from a desired machining shape, and tool wear. A machine tool having a correction function is provided. Another object of the present invention is to provide a machining method capable of obtaining a smooth machining shape without a step generated by tool replacement, and a machine tool having a tool wear correction function.
[0006]
[Means for Solving the Problems]
In view of the above object, the present invention detects the amount of tool wear at the end of machining, and continues the machining by matching the tool edge position at the end of machining with the tool edge position at the start of the next machining based on the detected tool wear amount. It is what you do.
[0010]
Ie In a machine tool for machining the workpiece by relatively moving the tool and the workpiece, a position command is generated based on a preset NC machining program, and the tool and the workpiece are relatively moved according to the generated position command. Position command generating means for instructing the tool, tool wear amount detecting means for detecting the amount of wear of the tool when machining of the workpiece is interrupted, and during machining of the workpiece Using the pre-stored wear amount per unit cutting length Tool wear amount estimating means for sequentially estimating the amount of tool wear, blade edge position correcting means for sequentially correcting the tool tip position so as to compensate for the tool wear amount estimated by the tool wear amount estimating means, and the detection Wear amount accumulation calculation means for accumulating the difference between the estimated tool wear amount and the estimated tool wear amount, and the cutting edge position of the tool when machining of the workpiece is interrupted based on the accumulated tool wear amount; Cutting edge position control means for matching the cutting edge position of the tool when resuming machining of the workpiece; The tool wear amount detected by the tool wear amount detecting means is compared with the tool wear amount estimated by the tool wear amount estimating means, and the unit cutting length stored in advance is used for the estimation so that they match. Wear coefficient correction means for successively correcting the amount of wear per contact; A machine tool having a tool wear correction function is provided.
[0011]
In the present invention, the amount of wear of a tool worn by machining is detected, and the cutting edge position of the tool before and after the machining interruption is matched based on the amount of wear, so that machining without a step can be performed. In addition, when the step of sequentially correcting the tool tip position so as to compensate for the amount of wear of the tool estimated in real time during machining is used in combination, the deviation between the desired machining shape and the actual machining shape can be reduced or eliminated.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0013]
In the following description, “desired machining shape” means a desired machining shape, “actual machining shape” means a machining shape actually obtained by machining, and “reference machining program” means , A machining program created so as to obtain a desired machining shape on the premise that the tool T is not worn during machining, and the “correcting machining program” It means that the reference machining program is modified so that the desired machining shape can be obtained in consideration of the deviation between the desired machining shape and the actual machining shape due to wear.
[0014]
First, with reference to FIG. 1, the structure of the main part of an NC machine tool 11 having a tool wear correction function according to the present invention will be described. The machine body of the NC machine tool 11 includes a spindle 15 rotatably supported by the spindle head 13 and a table 17 on which the workpiece W is placed and fixed. Based on an axis movement command from the NC device 19, An X-axis feed motor 21, a Y-axis feed motor (not shown), and a Z-axis feed motor 23 can move the main shaft 13 and the table 17 relative to each other in the three orthogonal directions of the X, Y, and Z axes. It is configured.
[0015]
In the NC machine tool 11 of FIG. 1, the table 17 is moved in the X-axis direction by the X-axis feed motor 21, and the main shaft 15 is moved in the Y-axis direction and the Z-axis direction by the Y-axis feed motor and the Z-axis feed motor 23. Thus, the main shaft 15 and the table 17 are relatively moved in the three orthogonal directions, but the main shaft 15 is moved in the three orthogonal directions by the X-axis feed motor 21, the Y-axis feed motor, and the Z-axis feed motor 23. Other configurations are possible, such as Here, the X axis and the Y axis indicate two orthogonal axial directions in a plane perpendicular to the rotation axis of the main shaft 15, and the Z axis indicates an axial direction parallel to the rotation axis of the main shaft 15.
[0016]
Further, a tool T is attached to the tip of the main shaft 13, and the tool T and the work W are moved relative to each other by moving the main shaft 15 and the table 17 relative to each other by turning the tool T while rotating the tool T. The workpiece W is processed into a desired shape by relatively moving in the axial and Z-axis directions.
[0017]
The NC device 19 includes a program storage unit 19a for storing various programs such as a machining program and a tool tip position measurement program, a reading interpretation unit 19b for interpreting a program stored in the program storage unit 19a, and an interpreted program. Axis movement control such as a position command generating means 19c for generating a position command for the spindle 15 and the table 17 according to the above, and a servo motor driver for driving the X-axis feed motor 21, the Y-axis feed motor, and the Z-axis feed motor 23 according to this position command Means 19d.
[0018]
The machine body of the NC machine tool 11 is provided with position reading means 25 for reading the coordinate values of the feed axes of the X axis, Y axis, and Z axis at any moment. The relative position of the spindle 15 with respect to the table 17 is fed back to the sequential axis movement control means 19d. As the position reading means 25, an appropriate device such as a digital scale attached to each feed shaft of the main shaft 15 or the table 17, an encoder attached to each of the X-axis feed motor 21, the Y-axis feed motor, and the Z-axis feed motor 23 is used. It is possible to use.
[0019]
Further, the NC machine tool 11 is provided with a tool edge position calculating means 27 so that the edge position of the tool T with respect to the spindle 15, preferably the distance between the front end surface of the spindle 15 and the edge position of the tool T, that is, the tool length can be measured. It has become.
[0020]
For example, the tool cutting edge position calculating means 27 moves the spindle 15 and the table 17 relative to each other, and the tool T mounted on the spindle 15 by the tool cutting edge detection device 29 provided at a position that does not interfere with machining on the table 17. The edge position of the tool T with respect to the spindle 15 is calculated from the relative position of the spindle 15 with respect to the table 17 detected by the position reading means 25 at this time. More specifically, since the cutting edge detection position of the tool cutting edge detection device 29 is a predetermined position with respect to the table 17, if the positions of the spindle 15 and the table 17 are detected, the spindle 15 and the tool cutting edge are detected. Using the fact that the distance from the detection position of the device 29 is known, the cutting edge position of the tool T with respect to the spindle 15 is calculated. The tool edge detection device 29 may be a contact type sensor as shown in FIG. 1, or may be a non-contact type sensor such as a laser type, a capacitance type or an eddy current type.
[0021]
The method by which the tool cutting edge position calculating means 27 calculates the cutting edge position of the tool T with respect to the spindle 15 is not limited to the above method, and the tool cutting edge position calculating means 27 is not limited to the above method. Needless to say, the blade edge position may be calculated.
[0022]
Now, in the NC machine tool 11 as described above, machining is normally performed according to a reference machining program created on the assumption that the tool T is not worn during machining and maintains a certain length. Therefore, as the tool T wears, the cutting edge position of the tool T approaches the spindle 15 side from the desired machining shape, and an actual machining shape deviated from the desired machining shape is obtained. Further, if the tool T is replaced at this time, even if the spindle 15 is arranged at the same position, the cutting edge position of the tool T approaches the table 17 side, so that a step is generated in the actual machining shape.
[0023]
Therefore, the NC machine tool 11 of the present invention performs tool machining while taking into account that the length of the tool T or the position of the cutting edge changes due to wear, a tool wear amount detection means 31, a wear coefficient correction means 32, A tool wear amount estimating means 33, a blade edge position correcting means 34, a wear amount accumulation calculating means 35, and a blade edge position control means 37 are further provided.
[0024]
The tool wear amount detection means 31 calculates and detects the wear amount of the tool T from the difference between the cutting edge position of the tool T before and after machining when processing a certain region, or after the previous machining by the tool T. The cutting edge position is set as the cutting edge position of the tool T before the current machining, and the wear amount of the tool T is calculated and detected from the difference from the cutting edge position of the tool T after the current machining.
[0025]
On the other hand, the tool wear amount estimation means 33 estimates the wear amount of the tool T from the cutting conditions, the processing load, the cutting length CL, and the like during processing. For example, the tool wear amount estimating means 33 stores in advance a wear coefficient Mk representing the wear amount per unit cutting length, and is a value obtained by integrating the cutting length CL of the tool T used for machining and the wear coefficient Mk. Based on the above, the wear amount of the tool T is sequentially obtained during machining. Further, the tool wear amount estimating means 33 can also estimate the total wear amount of the tool T being processed by adding the successively obtained wear amounts. Here, the cutting length CL means the length of the workpiece W cut.
[0026]
Based on the wear amount of the tool T estimated by the tool wear amount estimating means 33, the cutting edge position correcting means 34 sequentially sends a signal for correcting the wear amount to the position command generating means 19c or the shaft movement control means 19d to perform machining without any wear error. I do.
[0027]
Further, in order to set the wear coefficient Mk used for estimation more correctly, the wear amount of the tool T detected by the tool wear detection means 31 and the wear amount of the tool T estimated by the tool wear amount estimation means 33 are compared, Wear coefficient correction means 32 is provided for sequentially correcting the wear coefficient Mk so that they coincide with each other.
[0028]
The wear amount cumulative calculation means 35 adds the wear amount of the tool T obtained by the tool wear amount detection means 31 every time the machining is interrupted by tool change or the like, and the actual wear shape for the desired machining shape determined by the reference machining program is added. The amount of deviation of the machining shape at the time of machining interruption, that is, the error is obtained.
[0029]
Then, the blade edge position control means 37 changes the relative position between the spindle 15 and the table 17 by the wear amount of the tool T obtained by the wear amount detection means 31. This change in the relative position is performed by sending a signal from the blade edge position control means 37 to the position command generation means 19c or the shaft movement control means 19d. In this way, the cutting edge position of the tool T before and after the machining interruption is made coincident, and the influence of the wear of the tool T on the actual machining shape is removed or reduced.
[0030]
For example, when the tool length or the amount of wear changes discontinuously due to replacement of the tool T or the like, the position command generated by the position command generating unit 19c is corrected according to the reference machining program, and each of the pieces obtained by the tool wear amount calculating unit 31 is corrected. The accumulated value of the wear amount of the tool T, that is, the error between the desired machining shape and the actual machining shape obtained by the wear amount accumulation calculating means 35 is shifted in a direction away from the spindle 15 and the table 17 after the replacement of the tool T. I will let you. Thereby, the cutting edge position of the tool T with respect to the workpiece W before and after the replacement of the tool T coincides, and the step generated in the actual machining shape due to the amount of wear is eliminated.
[0031]
Further, when the tool length continuously changes due to wear, the position command generated by the position command generation means 19c is corrected according to the reference machining program, and only the wear amount of the tool T used is obtained by the tool wear amount estimation means 33. Then, the main shaft 15 and the table 17 are sequentially shifted in the direction of approaching. As a result, the change in the tool length due to the wear of the tool T is offset and compensated, and the cutting edge position of the tool T with respect to the workpiece W moves along the desired machining shape. Deviation from the desired machining shape is eliminated or reduced.
[0032]
Here, the correction of the position command can be performed by any one of a tool offset correction, a workpiece coordinate system correction, and a machine origin position correction of the NC machine tool 11.
[0033]
Next, the operation of the NC machine tool 11 shown in FIG. 1 will be described with reference to FIGS.
[0034]
Prior to machining, the operator sets a machining program and stores it in the program storage unit 19a. Here, it is assumed that a reference machining program created on the premise that the tool T does not wear is stored in the program storage unit 19a as a machining program. A modified machining program may be stored.
[0035]
Next, the NC machine tool 11 calculates the cutting edge position of the tool T with respect to the spindle 15 for the tool T mounted on the spindle 15 when machining is started by the tool cutting edge position calculation means 27 (step S1). Hereinafter, in order to simplify the description, it is assumed that the cutting edge position of the tool T with respect to the front end surface of the main shaft 15, that is, the tool length Ha is calculated in step S1. In addition, for simplification of description, it is assumed that the tool T having the same standard length is used in the following steps even after the tool T is replaced. In addition, the following procedures are not limited to the tool T of the same length, It cannot be overemphasized that it can apply with respect to the tool T of various length.
[0036]
When the calculation of the tool length Ha is completed, the reading and interpreting means 19b interprets the reference machining program stored in the program storage section 19a, and the position command generating means 19c generates position commands for the spindle 15 and the table 17 accordingly. The shaft movement control means 19d drives the X-axis feed motor 21, the Y-axis feed motor, and the Z-axis feed motor 23 in accordance with this position command to perform machining (step S2).
[0037]
Next, at a predetermined timing, the machining is interrupted for exchanging the tool T, and the relative positions of the spindle 15 with respect to the X axis, Y axis, and Z axis with respect to the table 17 at the time of interruption are obtained (step S3). The relative position between the spindle 15 and the table 17 may be obtained from the position command for the spindle 15 and the table 17 generated by the position command means 19c. As the positions of the main shaft 15 and the table 17 with respect to the X axis, the Y axis, and the Z axis, values detected by the position reading unit 25 can be used.
[0038]
Next, prior to the replacement of the tool T, the tool length Hb of the tool T worn by machining is calculated by the tool edge position calculating means 27 (step S4). Instead of step S3, the tool edge position calculating means 27 may calculate the tool length in a timely manner, and the processing may be interrupted when the tool length becomes shorter than a predetermined value. At this time, the last calculated tool length can be set as the tool length Hb at the time of machining interruption.
[0039]
Next, the tool wear amount detection means 31 calculates the wear amount Mt of the tool T from the tool length Ha at the start of machining and the tool length Hb at the time of machining interruption (step S5). Then, the tool wear amount detection means 31 sends the calculated wear amount Mt of the tool T to the wear amount accumulation calculation means 35, and the wear amount accumulation calculation means 35 accumulates based on the sent wear amount Mt of the tool T. The error amount Me is obtained and stored together with the relative positions of the spindle 15 with respect to the X axis, Y axis and Z axis with respect to the table 17 at the time of machining interruption (step S6). As a result, the relative positions of the spindle 15 with respect to the X axis, the Y axis, and the Z axis with respect to the table 17 when machining is interrupted, and the deviation amount between the actual machining shape and the desired machining shape at that position are stored.
[0040]
Since the sequential wear correction in step S7 will be described later, in step S7, it is assumed that the sequential wear correction is not performed, and the process proceeds to the next step S9, where the worn tool T mounted on the spindle 15 is replaced.
[0041]
When the tool T is exchanged and a new tool T is mounted on the spindle 15, the tool length Ha at the time of resuming the processing is calculated by the tool edge position calculating means 27 prior to resuming the processing in the same manner as in step S1. (Step S10). When the tool length Ha is calculated, machining using the new tool T is resumed (step S11).
[0042]
By the way, the new tool T is longer than the tool T used before the interruption by the wear amount Mt. On the other hand, the actual machining shape is shifted from the desired machining shape toward the main spindle 15 by the wear amount Mt of the tool T at the time of interruption. Therefore, when the machining is resumed, when the spindle 15 and the table 17 are moved to the same relative position as when the machining is interrupted, the cutting edge position of the tool T attached to the spindle 15 is arranged on the desired machining shape, Since the actual machining shape approaches the table 17 side by the wear amount Mt of the tool T, a step equal to the wear amount Mt occurs on the workpiece W.
[0043]
Therefore, in the NC machine tool 11 of the present invention, the position command generated by the position command generation means 19c for the spindle 15 and / or the table 17 is corrected by the blade edge position control means 37 and obtained by the wear amount accumulation calculation means 35. The relative position of the spindle 15 with respect to the table 17 is shifted away from each other by an amount equal to the accumulated error amount Me obtained, that is, at this stage, equal to the wear amount Mt of the tool T obtained by the tool wear amount detection means 31. In this state, the processing is continued (step S12).
[0044]
Next, similarly to step S3, when the calculated tool length becomes shorter than a predetermined value at a predetermined timing, the processing is interrupted in order to replace the worn tool T with a new tool T ( Step S13). Prior to the replacement of the tool T, the tool length Hb of the tool T worn by machining is calculated by the tool edge position calculating means 27 (step S14), and the tool wear amount detecting means 31 is the same as in step S5. The wear amount Mt of the tool T used in (1) is calculated (step S15), and the wear amount cumulative calculation means 35 calculates a cumulative error amount Me from the wear amount Mt and stores this (step S16).
[0045]
Since the sequential wear correction in step S17 will be described later, it is assumed in step S17 that the sequential wear correction is not performed and the process proceeds to step S18. When processing is continued in step S18, the procedure from step S9 to step S17 is repeated in the same manner. Note that the tool used in step S12 wears along with the machining in the same manner as the tool used in step S2. Therefore, when the machining is interrupted for tool replacement, the deviation between the desired machining shape and the actual machining shape does not occur. The sum of the wear amount Mt of the tool T used in step S2 and the wear amount Mt of the tool T used in step S12, that is, the accumulated error amount Me obtained by the wear amount accumulation calculating means 35 is equal. Therefore, in replacement of the tool T for the second and subsequent times, in step S12, the cutting edge position control means 37 shifts the relative position of the spindle 15 with respect to the table 17 in a direction away from each other by the accumulated error amount Me. Machining may be continued while correcting the position command generated by the command generating means 19c according to the reference machining program.
[0046]
As described above, by performing machining using the new tool T in consideration of the wear amount Mt of the used tool T, a step is generated in the actual machining shape at the position where the tool T is replaced, that is, at the machining interruption position. Is avoided.
[0047]
However, when machining is performed according to the above procedure, the step of the actual machining shape is eliminated, but a deviation from the desired machining shape occurs. Therefore, in the NC machine tool 11 of the present invention, the wear of the tool T during machining is also relative to the spindle 15 and the table 17 in accordance with steps S21 to S29 shown in FIG. It is made to compensate by correcting sequentially. The procedure will be described in detail below.
[0048]
First, the tool wear amount estimation means 33 reads a preset wear coefficient Mk from an arbitrary storage means or a machining program (step S21), and then monitors the cutting length CL (step S22). The cutting length CL may be obtained based on the relative movement distance of the spindle 15 with respect to the table 17 detected by the position reading means 25, or may be obtained from each axis movement command generated by the axis movement control means 19d.
[0049]
The tool wear amount estimation means 33 calculates the wear amount increment by accumulating the cutting length increment CL and the wear coefficient Mk, and sequentially cancels out the influence of the wear correction amount Ms, that is, the wear of the tool T. A correction amount required for the relative position between the spindle 15 and the table 17 is obtained (step S23). Then, the tool wear amount estimation means 33 calculates the total cutting length SCL and the total sequential correction amount SMs, which are the sum of the cutting length and the sequential wear correction amount Ms, from the cutting length increment CL and the sequential wear correction amount Ms. This is sent to the blade edge position correcting means 34 (step S24).
[0050]
The blade edge position correcting means 34 corrects the position command generated by the position command generating means 19c with respect to the spindle 15 and / or the table 17 (step S25), and the relative position of the spindle 15 with respect to the table 17 by the total sequential correction amount SMs. Processing is performed by shifting the positions toward each other (step S26).
[0051]
In step S27, when the processing is continued, the procedure from step S22 to step S26 is repeated.
[0052]
By sequentially correcting the relative position of the spindle 15 with respect to the table 17 in such a procedure, the influence of the wear of the tool T on the cutting edge position of the tool T during machining is offset, and the desired machining shape of the actual machining shape is obtained. The amount of deviation from is eliminated or reduced.
[0053]
In steps S22 to S26, since the wear amount of the tool T estimated by the tool wear amount estimating means 33 is used, the deviation amount between the actual machining shape and the desired machining shape may not be completely eliminated. is there. However, if machining is not continued in step S27, if the process returns to step S3 or step S13, there will be no step in the actual machining shape due to the deviation between the actual machining shape and the desired machining shape.
[0054]
Further, after step S27, the wear coefficient correction means 32 reads the wear amount Mt of the tool T obtained in step S5 or step S15 from the tool wear amount detection means 31 (step S28), and this wear amount Mt is read as the total cutting length. The wear coefficient Mk based on actual machining may be obtained by dividing by SCL (step S29). As a result, the wear coefficient Mk in accordance with the actual machining conditions and machining load can be obtained, and the deviation between the actual machining shape and the desired machining shape can be reduced.
[0055]
As another method for estimating the wear amount of the tool, it can be calculated from the cutting conditions such as the tool rotation speed, the feed speed per tooth, the cutting amount, the tool material, the tool type, the workpiece material, and / or the processing load.
[0056]
When the procedure for avoiding the step of the actual machining shape shown in FIG. 2 and FIG. 3 is used together with the procedure for sequentially correcting the wear of the tool T shown in FIG. It is necessary to partially change the procedure for avoiding the step of the actual machining shape, which is shown as step S8 or step S19.
[0057]
When sequential correction of wear of the tool T is performed, the deviation between the actual machining shape and the desired machining shape at the time of machining interruption is smaller than the wear amount of the used tool T by the total sequential correction amount SMs. Therefore, in step S8 and step S19, the wear amount cumulative calculation means 35 subtracts the total sequential correction amount SMs from the cumulative error amount Me representing the deviation amount between the actual machining shape and the desired machining shape, and takes the successive correction amount into account. I have to.
[0058]
As described above, the present invention has been described by taking the NC machine tool 11 shown in FIG. 1 as an example. However, in the above-described embodiment, the wear of the tool T is considered at the time of interruption / resumption of machining or sequentially during machining to obtain an actual machining shape. The present invention is not limited to the above embodiment, and is merely an example of a method for eliminating or reducing the difference between the generated step and the actual processed shape and the desired processed shape.
[0059]
For example, in the procedure of step S1 to step S19, it has been described that the machining is interrupted for the replacement of the tool T. However, in the first area in order to machine two different areas of the workpiece W with the same tool T, It is also possible to apply the above procedure when the first region is processed again after the processing is interrupted and the second region is processed. In this case, the spindle 15 and the table 17 are equal to the difference between the wear amount Mt of the tool T during the first processing of the first region and the wear amount Mt of the tool T during the processing of the second region. It is possible to avoid the occurrence of a step in the actual machining shape by shifting the relative position to the direction of approaching.
[0060]
Further, in step S5 and step S15, the tool wear amount estimating means 33 is used in place of the tool wear amount calculating means 31, and the sequential wear amounts estimated by the tool wear amount estimating means 33 are accumulated to obtain the same tool. It is also possible to obtain the total wear amount of the tool generated during a series of processing and send the obtained total wear amount to the wear amount accumulation calculating means 35. Even in this case, since the wear amount of the tool T is taken into consideration, the step difference of the actual machining shape that occurs before and after the tool change can be reduced at least as compared with the case where the wear amount is not taken into consideration.
[0061]
【The invention's effect】
As described above, according to the present invention, the amount of tool wear during processing is estimated or calculated, and the tool length generated due to tool wear at the time of interruption / resumption of processing performed for tool replacement or during processing. The change can be canceled by changing the relative position between the spindle and the table, and the step generated in the actual machining shape when the machining is interrupted / resumed and the deviation between the desired machining shape and the actual machining shape can be reduced or eliminated. Therefore, it is possible to obtain a machining shape with little deviation from a desired machining shape or a smooth machining shape without a step without being affected by tool wear.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main configuration of an NC machine tool according to the present invention.
FIG. 2 is a flowchart showing a procedure of a machining method that does not cause a step in the actual machining shape performed in the NC machine tool shown in FIG.
FIG. 3 is a flowchart showing a continuation of the procedure of the processing method of FIG. 2;
4 is a flowchart showing a machining method for obtaining an actual machining shape without deviation from a desired machining shape performed in the NC machine tool shown in FIG. 1. FIG.
FIG. 5 is a diagram showing a step generated in an actual machining shape at the time of tool change in the prior art.
[Explanation of symbols]
11 ... NC machine tools
15 ... Spindle
17 ... Table
19 ... NC device
19c ... Position command generating means
27: Tool edge position calculating means
31 ... Tool wear amount detecting means
32 ... Wear coefficient correction means
33 ... Tool wear amount estimation means
34 ... Cutting edge position correcting means
35 ... Cumulative wear amount calculation means
37 ... Cutting edge position control means
T ... Tool
W ... Work

Claims (1)

In the machine tool (11) for machining the workpiece (W) by relatively moving the tool (T) and the workpiece (W) ,
A position command generating means (19c) for generating a position command based on a preset NC machining program and commanding relative movement of the tool (T) and the workpiece (W) according to the generated position command;
Tool wear amount detecting means (31) for detecting the wear amount of the tool (T) when the machining of the workpiece (W) is interrupted;
Tool wear amount estimating means (33) for sequentially estimating the wear amount of the tool (T) using the wear amount per unit cutting length stored in advance during the machining of the workpiece (W) ;
Cutting edge position correcting means (34) for sequentially correcting the cutting edge position of the tool (T) so as to compensate the wear amount of the tool (T) estimated by the tool wear amount estimating means (33) ;
Wear amount accumulation calculating means (35) for accumulating a difference between the detected wear amount of the tool (T) and the estimated wear amount of the tool (T) ;
Tool when resuming the processing of the the position of the cutting edge of the tool (T) when the interrupting processing of said workpiece (W) based on the wear amount of the accumulated tool (T) the work (W) in (T) Cutting edge position control means (37) for matching the cutting edge position;
The wear amount of the tool (T) detected by the tool wear amount detection means (31) is compared with the wear amount of the tool (T) estimated by the tool wear amount estimation means (33) so that they match. Wear coefficient correction means (32) for sequentially correcting the amount of wear per unit cutting length stored in advance for estimation;
A machine tool equipped with a tool wear correction function.

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