JPH10293606A - Machining controller in machine tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically correct a working program not to make wasteful empty machining by rewriting a high-speed feeding instruction which instructs a faster feeding that machining feeding in a section where a tool actually does not cut a work. SOLUTION: A working controlling part 11 analyzes a working program PRO that is read from working program memory 4 and makes a spindle driving motor 16 perform rotation drive at a prescribed speed through a spindle controlling part 12. A mark is attached to a block that is undergone machining work, and as to a block to which a mark is attached machining time shortening program rewrite control is performed when an initial work 20 is machined. This brings distance where a milling tool 19 is fed with machining feeding close to distance where the work 20 is actually cut as much as possible, a section that is not actually cut is controlled at a feeding speed which is faster than the machining feeding, and the program PRO is controlled to be rewritten so that wasteful air cut may not occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting control device for a machine tool capable of modifying a machining program so as to minimize empty cutting.

[0002]

2. Description of the Related Art Conventionally, in a machine tool, a tool is fed at a rapid traverse to a position as close to a work as possible at the time of creation of a machining program so as to prevent useless empty cutting by a cutting feed, and thereafter, machining is performed by a cutting feed. However, if the workpiece to be machined is a material with black skin or the shape of the workpiece to be machined is complicated, the tool should be positioned at the very end of the workpiece by rapid traverse. It is difficult to program because of the danger of collision between the tool and the workpiece. Therefore, a sufficient clearance is set between the tool and the workpiece in advance.

[0003]

Then, at the time of actual machining, the tool is fed by the cutting feed at the time of such a clearance, so that there is a considerable occurrence of an empty cutting state in which the workpiece is not actually machined. Become. In particular, when machining a large number of identical workpieces, the total time of such blank cutting is prolonged so as not to be ignored.

[0004] In order to solve such a point, the first piece of the work is test-cut, and the cutting state is checked.
Although a method in which the operator manually corrects the program so that no empty cutting occurs is also used, it is not only time-consuming but also that the machine tool operator needs to have the program's expertise in correcting the program. This is inconvenient.

[0005] In view of the above circumstances, the present invention can automatically correct a machining program so that useless empty cutting is minimized by merely machining the first workpiece based on the machining program. An object of the present invention is to provide a cutting control device in a machine tool that does not require an operator to manually correct a program.

[0006]

That is, of the present invention, the invention of claim 1 has a cutting feed command (G1) by a cutting feed suitable for a cutting operation, and the cutting of a workpiece is performed by the cutting feed command. Cutting block to instruct (N102, N104)
And a first memory means (4) for storing a machining program (PRO) having the following configuration. The tool (19) is relatively moved with respect to a workpiece to be machined based on the machining program to perform a predetermined machining. Machine tool (1) that performs
A second memory unit (4) for storing a rewrite instruction mark (MK) for instructing rewriting of a specific cutting block of the machining program, and storing a specific cutting block of the machining program designated by the rewrite instruction mark; Processing execution means (11, 14, 15, 16, 25) for executing
A cutting load detecting means for detecting a cutting load (LD) acting on the tool and outputting it as a cutting load signal while the specific cutting block is being executed by the machining executing means;
And a cutting state determining means (8) for determining an actual cutting state of the workpiece by the tool based on a cutting load signal from the cutting load detecting means, and the cutting state is changed by the cutting state determining means. A tool position detecting section (18) for detecting the position of the tool when it is determined that the cutting state determination signal from the cutting state determining section and the cutting state detected by the tool position detecting section change. From the tool position at the time of execution, a high-speed feed command that commands a faster feed than the cut feed in a section of the specific cutting block of the machining program instructed by the rewrite instruction mark, in which the tool is not actually cutting the work. A program rewriting means (6) for rewriting is provided.

In the present invention, the rewriting instruction mark (MK) is stored in a cutting block (N102, N104) for instructing rewriting in a machining program. You.

According to a third aspect of the present invention, in the invention, the machining execution means includes a spindle drive motor (1) for rotationally driving the tool.
6), and the cutting load detecting means (13) is configured to output a cutting load signal based on a load current of the spindle drive motor. According to a fourth aspect of the present invention, the machining executing means has a feed shaft drive motor (25) for moving and driving the feed shaft, and the cutting load detecting means has a load current of the feed shaft drive motor. The cutting control device for a machine tool according to claim 1, wherein the cutting load signal is output based on the cutting load signal.

According to a fifth aspect of the present invention, there is provided a clearance parameter storage means (10) for storing a clearance parameter (α), wherein the program rewriting means is designated by the rewriting instruction mark. When rewriting the section of the specific cutting block of the machining program in which the tool is not actually cutting the workpiece into a high-speed feed command, rewriting is performed in consideration of the clearance parameter set by the clearance parameter storage means. The program rewriting means (8) is constituted. Note that the numbers and the like in parentheses are for convenience showing the corresponding elements in the drawings, and therefore, this description is not limited to the description on the drawings. The same applies to the following “action” column.

[0010]

According to the above construction, the invention of claim 1 of the present invention provides a cutting block (N102,
N104), the empty cutting portion also receives a cutting feed command (G
High-speed feed command (G
0).

According to a second aspect of the present invention, there is provided a cutting block (N1) to be rewritten by the machining executing means.
02, N104) can be recognized simply by reading the block.

The third aspect of the present invention operates so that a cutting load signal can be directly obtained from the spindle drive motor (16) for driving the tool. According to a fourth aspect of the present invention, a feed shaft drive motor (2) for driving a feed shaft is provided.
From 5), the cutting load acting on the tool is indirectly detected and the cutting load signal can be obtained.

According to a fifth aspect of the present invention, a tool (1) is provided.
9), immediately before the tool starts actual cutting of the workpiece,
Positioning can be performed by a high-speed feed command (G0) at a high speed with a predetermined clearance (α) interposed.
Alternatively, immediately after the tool completes the actual cutting of the work, a high-speed feed command (G0) by a fast feed can be executed with a predetermined clearance therebetween.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an example of a machining center using a cutting control device in a machine tool, FIG. 2 is a diagram showing an example of a machining program, FIG. 3 is a diagram showing an example of a cutting time reduction program, and FIG. 5 shows an actual machining state of the work by the machining program shown in FIG. 5, FIG. 5 shows another machining example of the work, FIG. 6 shows a modification example of the machining program, and FIGS. It is a figure showing a processing example.

As shown in FIG. 1, a machining center 1 using a cutting control device in a machine tool has a main control unit 2, and the main control unit 2 has a processing program memory via a bus line 3. 5, program rewriting unit 6, cutting state determination unit 8, system program memory 7, display 9, keyboard 10, machining control unit 11, spindle feed control unit 14, spindle control unit 12, spindle load calculation unit 13, table feed control unit 15, a tool position detecting unit 18 and the like are connected. A spindle drive motor 16 is connected to the spindle control unit 12 and the spindle load calculation unit 13. The spindle 17 is connected to the spindle drive motor 16 by the spindle drive motor 16.
Are rotatably connected. A milling tool 19, which is a rotary tool, is detachably mounted on the main spindle 17, and a drill tool (not shown) and the like, which are not shown, can be detachably mounted on the main spindle 17 by a known tool changing device. Can be attached to The main shaft 17 is provided so as to be movable in the vertical direction in the drawing, which is the Z-axis direction, that is, in the directions of arrows A and B by a main shaft feed motor (not shown) via the main shaft feed control unit 14, and the lower part of the main shaft 17 in the drawing A table 21 on which a workpiece 20 to be processed is mounted is driven by a table drive motor 25 in an X-axis direction perpendicular to the Z-axis direction, that is, in directions parallel to the sheet of FIG. It is provided so as to be movable and movable in the Y-axis direction which is a direction perpendicular to the paper surface and perpendicular to the paper surface. In the machining center 1, the main shaft 17 is moved in the Z direction, and the table 21 is moved in the Y and Z directions perpendicular to the Z axis. However, the XYZ axis configuration is optional. It goes without saying that various shaft configurations are adopted depending on the machine.

Since the machining center 1 has the above-described configuration, when the machining center 1 is used to machine a workpiece 20 using the milling tool 19, the main control unit 2 reads a machining program from the machining program memory 4. Then, the processing controller 11 is instructed to perform a predetermined processing based on the read processing program. The machining control unit 11 analyzes the read machining program, drives the spindle drive motor 16 to rotate at a predetermined peripheral speed via the spindle control unit 12, and rotates the spindle 17 via the spindle feed control unit 14. Is appropriately moved and driven in the Z-axis direction, and the table 21 is appropriately moved and driven in the X and Y directions via the table feed control unit 15 and the table drive motor 25, so that the table 20 is moved to the workpiece 20 by the milling tool 19 mounted on the main shaft 17. Perform processing.

The machining program read from the machining program memory 5 is a machining program PRO shown in FIG.
(Only the main part of the machining program is shown in FIG. 2 for simplicity of description), in block N100 of the machining program PRO, G0 X-10 Y10 is set, and the milling tool 19 is moved to coordinates X-10 Y10. Is instructed to perform positioning movement by rapid traverse. Next, block N1
In 01, it is set to G0 Z-5, and it is instructed to position the milling tool 19 to the coordinate Z-5 by rapid traverse. At this point, the milling tool 19 is positioned at the position P1 shown in FIG. Next, block N
At 102, G1 X110 F500! 1;
At a cutting feed rate of 00 mm / min, a command is issued to move the tool 19 to a position P2 shown in FIG. 4 of X110 by linear interpolation.
And a predetermined cutting process is performed. next,
In block N103, G0 Y50; is set, and it is instructed to perform fast-forward positioning movement from the position P2 shown in FIG. 4 to the coordinate Y50, and further, in block N104, G01X-1.
0! 1; it is instructed to move to X-10 by linear interpolation with a cutting feed. In this block, the milling tool 19 moves by the same distance in the opposite direction of the block N102 to perform a predetermined cutting operation. Is performed. Further, in block N105, G0
Z5; it is instructed to move to the coordinate Z5 by rapid traverse.

When performing the machining based on the machining program PRO, a block N102 (also in the block N104, the cutting direction is the reverse direction and the content is the same, so only the block N102 will be described here).
As shown in FIG. 4, the milling tool 19 has a distance L1 from the first positioned position P1 to a position P3 where the milling tool 19 actually contacts the workpiece 20, and a distance L1 from the position P3 to the position P4. The distance L3 for actually cutting the work 20 and the distance L2 from the end of the cutting of the work 20 at the position P4 to the further movement to the position P2 are all driven and controlled by linear interpolation in the cutting feed.

Therefore, when the workpiece is machined as instructed by the machining program PRO, in block N102, the milling tool 19 moves the positions P1 and P3 and the position P4.
Between the distances L1 and L2 between P2 and P2, unnecessary air cutting is performed without actually processing the work. However, when creating the machining program PRO, the distances L1 and L2 between the positions P1 and P3 and the positions P4 and P2 are different.
In consideration of the above, it is practically impossible to create a program so that the distance becomes zero, because there is a high risk that the milling tool 19 and the workpiece 20 collide in the rapid traverse state.
Therefore, at the time of creating the machining program PRO, as shown in FIG.
For example, when a mark MK of “! 1” is added to the block 4 and the processing control unit 11 interprets the block to which the mark MK is attached, the first work is applied to the block to which the mark MK is attached. When machining a milling tool, the milling tool 19
Is controlled so that the distance sent by the cutting feed is as close as possible to the distance L3, and the machining program PRO is rewritten so that unnecessary air cut does not occur.

That is, when machining the first work 20 based on the machining program PRO read from the machining program memory 5, the machining control unit 11 simultaneously reads the cutting time reduction program CTS from the system program memory 7 and executes the program CTS. The rewriting control of the machining program PRO is performed as necessary based on the program. That is, the processing control unit 11 controls the normal blocks of the processing program PRO, that is, the blocks without the mark MK of “! 1”, for example, the blocks N100 and N10 in FIG.
When interpreting 1, N103, N105, etc., FIG.
Then, the process enters step S3 via steps S1 and S2 of the cutting time shortening program CTS, and ends the block of the machining program PRO as it is.

When interpreting a block to which a mark MK "! 1" is attached in the block of the machining program PRO, for example, the blocks N102 and N104 in FIG. 2, the step S1 of the cutting time shortening program CTS is performed. From step S2 through step S2, for example, in the case of block N102, the "cutting flag" indicating whether or not the current tool state stored in the memory in the processing control unit 11 is cutting is turned off. State and step S5
It is determined whether the cutting flag is in the OFF state. In this case, since it is in the OFF state, the process proceeds to step S6,
The processing control unit 11 instructs the cutting state determination unit 8 to determine the cutting state of the milling tool 19,
The execution of block N102 is instructed to the spindle control unit 12 and the table feed control unit 15.

In response, the cutting state determination unit 8 instructs the spindle load calculation unit 13 to calculate the load state of the spindle drive motor 16, and the spindle load calculation unit 13
, A spindle load LD acting on the spindle drive motor 16 is calculated from the current value, and is output to the cutting state determination unit 8 as a cutting load signal.

That is, at this point, the machining program PR
Since the machining by O has entered the execution stage of block N102, the milling tool 19 is positioned at the position P1, as shown in FIG.
F500 is executed, and the milling tool 19 is fed by linear interpolation at a cutting feed rate of 500 mm / min relative to the direction of arrow D in FIG. Then, as already described, the tool 19 is sent in the idle cutting state from the position P1 to the position P3, comes into contact with the work 20 at the position P3, and the actual cutting of the work 20 is started. At this time, since the spindle drive motor 16 is in the idle cutting state up to the position P3, its load current is a low current value in a normal idle cutting state.
When the actual cutting of the work 20 is started after reaching the position P3,
The load current value increases in accordance with the cutting force acting on the tool 19. Then, the spindle load LD calculated by the spindle load calculation unit 13 naturally increases, and the cutting state determination unit 8 determines from the change in the spindle load LD that the cutting of the work 20 by the tool 19 has started, and Milling tools 19
Is instructed to the tool position detecting unit 18 to detect and latch, and the cutting start signal SN1 is transmitted to the machining control unit 11.
Output to On the other hand, the tool position detection unit 18 detects the current position of the tool 19 from the driving state of the spindle 17 and the table 21 by the spindle feed control unit 14 and the table feed control unit 15, and latches the value.

The determination of the start of cutting of the workpiece 20 by the tool 19 by the cutting state determining unit 8 is performed by detecting a change in the spindle load LD of the spindle drive motor 16 as described above, and also by determining whether X or A method of detecting the drive load in the Y-axis direction, that is, a change in the table drive load of the table drive motor 25 that drives the table is applied to a tool by providing the table drive motor load calculator and the like. Naturally, it is also possible to detect the cutting load indirectly. When the tool 19 is a drill or the like, the cutting load acting on the tool is indirectly determined from the change in the main shaft feed driving load of the main shaft feed motor that drives the Z axis direction feed shaft that feeds the main shaft 17 in the Z axis direction. It can also be detected. When the cutting start signal SN1 is thus input to the machining control unit 11, the machining control unit 11 enters step S7 of the cutting time reduction program CTS, and instructs the program rewriting unit 6 to block the currently executed machining program PRO. At the same time as instructing rewriting of the program related to N102, the cutting flag FL stored in the
N state.

The program rewriting section 6 receives a rewriting command from the machining control section 11 and calculates the coordinate position of the milling tool 19 at the position P3 in FIG. As shown in FIG. 6A, the block N1 of the currently executed machining program PRO is
02, G1 X110 F500! 1; in FIG.
As shown in (b), while the command instructs the linear interpolation by the cutting feed, the position P where the idle cutting is actually performed is performed.
From 1 to P3, a block is generated to change from linear interpolation by cutting feed to positioning mode by rapid feed, and the line immediately before the original command of the currently executing machining program PRO stored in the machining program memory 5 is generated. And add the block N102 to N102 G0 X (x1); G1 X110F 500! 1; and rewritten into a sequence consisting of two blocks. Note that x1 in parentheses is the X coordinate value of the position P3.

When the rewriting is completed, the processing control section 11 enters step S8 of the cutting time reduction program CTS, and determines whether or not the execution of the block N102 has been completed, that is, the tool 19 has reached the position P2 in FIG. It is determined whether or not the cutting has been performed. If the tool 19 is still cutting the workpiece 20, the process returns to step S5, and the cutting flag FL is turned off.
It is determined whether or not. Since the flag FL has been rewritten to ON in step S7, the process proceeds to step S9, where the cutting state determination unit 8 determines whether or not the cutting of the work 20 by the tool 19 has been completed. The tool 19 is located between the positions P3 and P4 in FIG. 4, and it is determined from the spindle load LD output from the spindle load calculation unit 13 that the actual cutting of the work by the tool 19 is still being performed by the tool 19. When the unit 8 determines and outputs the cutting continuation signal SN2 to the machining control unit 11, the machining control unit 11 executes the cutting time reduction program CTS.
Then, the process returns from step S8 to step S9 via step S5, and waits until the cutting state determination unit 8 determines that the cutting of the work 20 by the tool 19 has been completed.

In this way, while the block N102 is being executed, the tool 19 passes through the right end of the work 20 in FIG. 4 and reaches the position P4, and the actual cutting of the work 20 is completed. The load LD of the spindle drive motor 17 that is output is changed from a high value indicating the actual cutting state until then,
When the value has changed to a low value indicating the idle cutting state, the cutting state determination unit 8 that supplements the change indicates the current milling tool 1.
9 is detected and latched via the tool position detector 18 and the actual cutting end signal SN3 is sent to the machining controller 11.
Output to In response to this, the machining control unit 11 executes steps S9 to S9 of the cutting time reduction program CTS.
In step 10, the program rewriting unit 6 is instructed to further rewrite the program related to the block N <b> 102 of the currently executed machining program PRO, and the cutting flag FL stored therein is turned off. .

The program rewriting unit 6 receives a further rewriting command from the machining control unit 11, receives the coordinates of the milling tool 19 at the position P4 in FIG. From the position, a position between the position P3 and the position P4 where the actual actual cutting was performed is set to the original block N10.
2. Generate a block to be linearly interpolated by cutting feed, which is sent at the feed speed F500 specified in Step 2, and further correct the remaining part from the position P4 where the cutting is completed to the position P2 to be a block to be set to the positioning mode by rapid feed. , FIG.
As shown in (b), the sequence of the block N102 of the currently executed machining program PRO stored in the machining program memory 4 and already rewritten once is shown in FIG. 6 (b) as N102 G0 X (X1); G1 X110 F500! 1; and further, as shown in FIG. 6C, N102 G0 X (x1); G1 X (x2) F500; G0 X110! 1; and modified to a sequence consisting of three blocks. In addition,
X2 in parentheses is the X coordinate value of the position P4.

When the rewriting is completed, the processing control section 11 enters step S8 of the cutting time reduction program CTS, and determines whether or not the execution of the block N102 has been completed, that is, the tool 19 has reached the position P2 in FIG. If the tool 19 has not yet reached the position P2 and the execution of the block N102 has not been completed, the flow returns to step 5 to determine whether or not the cutting flag FL is OFF. judge. Since the flag FL has been rewritten to OFF in step 10, the process proceeds to step S6, and the cutting state determination unit 8
Then, it is determined whether or not the cutting of the work 20 by the tool 19 is started again. The tool 19 is, for example, shown in FIG.
As shown in (1), when the machining from the position P1 to P2 is indicated by G1 which is a linear interpolation command by cutting feed in the block of the original machining program, the tool 1
9 finishes the actual cutting of the work 20, reaches the positions P4, P6, etc., contacts the work again at the positions P5, P7, etc., and starts the actual cutting. In step S7, the position between the positions P4 and P5, and between P6 and P7, a command for rewriting the linear interpolation command G1 based on the initial cutting feed to the positioning command G0 based on the rapid feed is generated by the program rewriting unit 6, and further, the process proceeds to step S9. S
At 10, a section between the positions P5 and P6, and the positions P7 and P8
In the same procedure as described above, a section in which linear interpolation is performed by cutting feed is generated, and only a section in which the tool 19 is actually in contact with a workpiece and performing a cutting operation is defined as a linear interpolation command G1 by cutting feed. , The other section where idle cutting is being performed is set to the positioning command G0 by rapid traverse,
The original machining program PRO will be modified.

In the case of FIG. 4, since the actual cutting is not started again until the tool 16 reaches the position P2 in the step S6, the process proceeds to the step S8 and the block N10 is started.
2, that is, G1 X110 F500! 1; When the end of the block is confirmed by the machining control unit 11, the program rewriting unit 6 responds to a signal from the machining control unit 11 to execute a sequence corresponding to the block N102 of the machining program PRO being rewritten in the machining program memory 5. Is shown in FIG. , The mark MK is deleted, and as shown in FIG. And rewrite it to the final form.

In the above embodiment, the cutting feed command G1
Has been described in the case of the idle cutting in the case of rewriting to the positioning command G0 by rapid traverse. However, since the feed speed in the section of the idle cutting may be rewritten to the high speed feed command which is faster than the actual cutting feed speed, FIG. As shown in (e), the command greatly increases the feed speed while maintaining G1 of the linear interpolation command, for example, F20000, that is, the cutting feed speed is set to 20000 mm / min, and N102 G1 X (x1 ) F20000; G1 X (x2) F500; G1 X110 F20000; ,

In this way, the machining of the first work 20 is executed by the corresponding machining program PRO, and when the execution of the block N102 in FIG. 2 is completed, the machining control unit 11 executes the next block N103 and the subsequent steps. The cutting time reduction program CTS in FIG. 3 also enters step S3, and determines whether the execution of the machining program has been completed. Since the machining program PRO ends in block N105, the cutting time reduction program CTS does not end in the execution stage of block N103, and returns to step S2, and the block to which the next mark MK is attached is processed by the machining control unit 11. Enter the state of waiting for interpretation.

The machining control unit 11 executes the machining program PRO
When the execution of the block N104 is started and the mark MK in the block is identified, the processing control unit 11 returns to FIG.
Step S4 is entered from step S2 of the cutting time reduction program CTS, and rewriting and modification of the machining program PRO are executed in the same procedure as described above. Thus, the original machining program PRO for the first workpiece 20
Is completed, the execution of the cutting time reduction program CTS in FIG. 3 is also terminated, and the cutting block marked with the mark MK of the corresponding processing program PRO is stored in the processing program memory 4 (for example, in the case of FIG. 2). , Blocks N102 and N104), only in the section where the milling tool 19 is actually in contact with the workpiece 20, linear interpolation is commanded in an appropriate cutting feed state by the corresponding tool, and in other empty cutting sections, higher speeds are used. The machining program PROM rewritten with a positioning command instructed to perform a proper feed is stored.

Therefore, when machining the second work, the main control unit 2 reads the rewritten machining program PROM from the machining program memory 5 and deletes the second and subsequent works based on the machining program PROM. To be processed. Then the machining program is already
When machining the first work, the linear interpolation command G1 due to useless cutting feed due to idle cutting is rewritten to the positioning command G0 at a high feed rate. The processing is performed in a form in which the empty cutting by a small cutting feed is suppressed as much as possible.

In the above-described embodiment, the machining program in which the linear interpolation command G1 is used as the cutting command by the cutting feed has been described. However, the present invention is not limited to the linear interpolation command G1 as the cutting command but the circular interpolation G2. , G3, etc., as long as it is a command for cutting a workpiece.

Further, in the above-described embodiment, the program rewriting section 6 directly uses the X coordinate positions of the positions P3 and P4 in FIG. 4, and as shown in FIG.
(X1) and the linear interpolation command G1 X (x2) are generated, but each command is converted to G0 X (x1−α) by the parameter α or the like previously input to a predetermined parameter memory from the keyboard 10 or the like by the operator. And G1 X (x2
As + α), it is of course possible to rewrite the machining program PRO such that the positioning command and the cutting command of the milling tool 19 maintain a slight clearance α from the workpiece 20.

In the above-described embodiment, the case where the present invention is applied to the case where a work is machined using the milling tool 19 as a tool has been described. However, the present invention is not limited to the case where the milling tool 19 is used for machining. When creating a machining program, the present invention can be applied to machining with any tool for which extra empty cutting must be expected. For example, as shown in FIG. 7, when a drill hole 20a is drilled in a workpiece 20 in which a center hole 20b has already been drilled, the contact start position between the workpiece 20 and the tool 22 is immediately determined at the stage of creating a machining program. Since it is not clear, in the case of a normal machining program, the complicated drill contact position calculation is not performed, and the drill tool 22 for drilling a drill hole is moved to an appropriate position P above the center hole 20b in the machining program.
A positioning command G0 is issued by rapid traverse up to 1, and then a linear interpolation command G1 is issued by cutting feed. In this case, in a section between the position P1 where the drill tool 22 is positioned and the position P3 where the drill tool 22 actually contacts the workpiece 20 and the actual cutting is started, the empty cutting by cutting feed is performed. However, by applying the present invention, a position from the position P1 to a position P3 at which the drill tool 22 actually contacts the workpiece 20 (or a position immediately before the position) P3 is determined as a positioning command G0 by rapid traverse. Linear interpolation command G1 by cutting feed
As a result, it is possible to prevent the occurrence of idle cutting due to the cutting feed between the sections P1 and P3, and to shorten the processing time.

Further, as shown in FIG.
When the center hole drill tool 22 chamfers 20b the work 20 in which
Since the starting position of contact between the tool 0a and the tool 22 is not immediately known at the stage of creating a machining program, a conventional machining program does not require complicated calculation of the drill contact position, and therefore a center hole drill tool for center hole machining. In the machining program 22, a positioning command G0 by rapid traverse to an appropriate position P1 above the drill hole 20a is commanded, and then a linear interpolation command G1 by cutting feed is transmitted to the position P1.
Up to 2. In this case, in the section between the position P1 where the center hole drill tool 22 is positioned and the position P3 where the center hole drill tool 22 actually contacts the workpiece 20 and the actual cutting is started, the empty cutting by the cutting feed is performed. However, by applying the present invention, the position command from the position P1 to the position P3 at which the center hole drill tool 22 actually contacts the work 20 (or the position immediately before the position P3) is set as the positioning command G0 by rapid traverse. From the position P3 to the position P2, the linear interpolation command G1 by the original cutting feed is used as the linear interpolation command G1, so that it is possible to prevent the occurrence of idle cutting due to the cutting feed between the sections P1 and P3, and to shorten the processing time.

In the above embodiment, the machining program P
Mark MK instructing rewriting of each block in RO
Has been described in the case where data is stored in a block to be rewritten, for example, in blocks N102 and N104 in FIG. 2. May be stored in some kind of memory in the form of a command indicating a block in the machining program to be rewritten by the operator from a keyboard or the like away from the machining program PRO. It is.

[0040]

As described above, according to the present invention,
Processing that has a cutting feed command such as a linear interpolation command G1 by a cutting feed suitable for a cutting operation, and stores a processing program PRO having cutting blocks such as blocks N102 and N104 that instruct the cutting of the work 20 by the cutting feed command. A machine tool having first memory means such as a program memory 5 and performing predetermined machining by moving a tool such as a milling tool 19 relative to a workpiece 20 to be machined based on the machining program. And a second memory means such as a machining program memory 5 for storing a rewriting instruction mark for instructing rewriting of a specific cutting block of the machining program, and a specific cutting block of the machining program designated by the rewriting instruction mark. Controller 11, spindle drive motor 16, spindle feed controller 14, table Machining execution means such as a feed control unit 15 and a table drive motor 25 are provided, and a cutting load such as a spindle load LD acting on the tool is detected while the specific execution block is being executed by the machining execution means. A cutting load detecting unit such as a spindle load calculating unit 13 that outputs a signal is provided, and a cutting state determining unit 8 that determines an actual cutting state of a workpiece by the tool based on a cutting load signal from the cutting load detecting unit. Is provided, a tool position detecting unit 18 that detects a position of the tool when the cutting state is determined to have changed by the cutting state determining unit, and a cutting state from the cutting state determining unit is provided. From the determination signal and the tool position at the time when the cutting state detected by the tool position detection unit has changed, the processing program specified by the rewrite instruction mark is specified. Since the cutting block is provided with a program rewriting means such as a program rewriting unit 6 for rewriting a section in which the tool is not actually cutting the workpiece to a high-speed feed command for commanding a feed faster than the cutting feed, the machining program Also in the cutting block by the cutting feed command instructed in a form that includes useless empty cutting, the empty cutting portion is rewritten and changed to a high-speed feed command by a feed faster than the cutting feed of the cutting feed command, so the first By simply machining the work based on the machining program, the machining program will be automatically corrected so that unnecessary idle cutting will not occur as much as possible, and the machine tool operator will not need to manually correct the program, etc. It is convenient.

If the rewriting instruction mark is stored in a cutting block for instructing rewriting in the machining program, the machining execution means recognizes the cutting block to be rewritten only by reading the block. This eliminates the need to search for the block indicated by the rewrite instruction mark in the machining program each time, and enables high-speed control.

The machining execution means has a spindle drive motor 16 for rotating and driving the tool, and the cutting load detecting means drives the tool by outputting a cutting load signal based on the load current of the spindle drive motor. Since the cutting load signal can be directly obtained from the main spindle drive motor, the cutting state of the tool can be accurately determined. The machining execution means includes a table drive motor 25 for moving and driving a feed shaft such as the table 21 and the main shaft 17 and a feed shaft drive motor such as a main shaft feed motor (not shown). When the cutting load signal is output based on the load current of the drive motor, the cutting load acting on the tool can be indirectly detected from the feed shaft drive motor that drives the feed shaft to directly obtain the cutting load signal. .

A keyboard 10 for storing clearance parameters such as the parameter α, and clearance parameter storage means such as a parameter memory are provided. The program rewriting means performs a specific cutting of the machining program specified by the rewriting instruction mark. When rewriting a section of the block in which the tool is not actually cutting the work into a high-speed feed command, the program rewriting means rewrites in a form taking into account the clearance parameter set by the clearance parameter storage means. With this configuration, the tool can be positioned by a high-speed feed command at a fast feed with a predetermined clearance immediately before the tool starts actual cutting of the work, or the tool can perform actual cutting of the work. Immediately after completion, the specified clearance A high-speed feed command can be executed by intermittent high-speed feed, and before and after the actual cutting of the workpiece is completed, the workpiece and the tool can be used for the actual cutting of the workpiece at a rapid feed rate due to some reason such as dispersion of the workpiece. It is possible to reliably prevent the occurrence of a situation in which the feed is performed or the feed is switched to a fast feed just before the end of the actual cutting, thereby improving the reliability of the machining.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a machining center using a cutting control device in a machine tool.

FIG. 2 is a diagram showing an example of a machining program.

FIG. 3 is a diagram showing an example of a cutting time reduction program.

FIG. 4 is a view showing an actual machining state of a workpiece by the machining program shown in FIG. 2;

FIG. 5 is a diagram showing another processing example of a work.

FIG. 6 is a diagram showing a modification example of a machining program.

FIG. 7 is a diagram showing another processing example of the work.

FIG. 8 is a diagram showing another processing example of a work.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Machine tool (machining center) 5 ... 1st memory means, 2nd memory means (processing program memory) 6 ... Program rewriting means (program rewriting part) 8 ... Cutting state determination means, tool position detection part (Cutting state determination unit) 11 Processing execution unit (processing control unit) 13 Cutting load detection unit (spindle load calculation unit) 14 Processing execution unit (spindle feed control unit) 15 Processing execution unit (table) Feed control unit 16 Machining execution means (spindle drive motor) 18 Tool position detection unit 19 Tool 20 Work 25 Work execution means (table drive motor) MK Rewrite instruction mark (mark) LD: Cutting load (spindle load) PRO: Machining program

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Akimitsu Nagae 1st boarding, Oguchi-machi, Oguchi-cho, Niwa-gun, Aichi Prefecture Yamazaki Mazak Co., Ltd.

Claims (5)

[Claims] A first memory means for storing a machining program having a cutting feed command by a cutting feed suitable for a cutting operation, and having a cutting block for commanding cutting of a workpiece by the cutting feed command; In a machine tool that performs a predetermined machining by moving a tool relative to a workpiece to be machined based on a machining program, a rewriting instruction mark for instructing rewriting of a specific cutting block of the machining program is stored. A machining execution unit for executing a specific cutting block of the machining program instructed by the rewriting instruction mark, wherein the machining execution unit is executing the specific cutting block; Cutting load detecting means for detecting an acting cutting load and outputting it as a cutting load signal; Based on the load signal,
Providing cutting state determination means for determining the actual cutting state of the work by the tool, provided with a tool position detection unit for detecting the position of the tool when it is determined that the cutting state has changed by the cutting state determination means, From the cutting state determination signal from the cutting state determination unit, and from the tool position when the cutting state detected by the tool position detection unit changes, the specific cutting block of the processing program instructed by the rewrite instruction mark A cutting control device for a machine tool, comprising a program rewriting means for rewriting a section in which the tool is not actually cutting a workpiece to a high-speed feed command for commanding a feed faster than the cutting feed. 2. The cutting control device for a machine tool according to claim 1, wherein said rewriting instruction mark is stored in a cutting block for instructing rewriting in a machining program. 3. The machining execution means has a spindle drive motor for rotating a tool, and the cutting load detection means outputs a cutting load signal based on a load current of the spindle drive motor. Item 3. A cutting control device for a machine tool according to Item 1. 4. The machining executing means has a feed shaft drive motor for moving and driving the feed shaft, and the cutting load detecting means outputs a cutting load signal based on a load current of the feed shaft drive motor. The cutting control device for a machine tool according to claim 1, wherein 5. A clearance parameter storing means for storing a clearance parameter, wherein said program rewriting means, said tool actually cuts a workpiece of a specific cutting block of a machining program specified by said rewriting instruction mark. 2. The machine tool according to claim 1, wherein the program rewriting means is configured to rewrite in a form in which the clearance parameter set by the clearance parameter storage means is taken into account when rewriting the section not performed by the high-speed feed command. Cutting control device.