JPH11188572A - Blade tip positioning method in tool change of nc machine tool and nc machine tool executing this method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the machining accuracy and operation rate of an NC machine tool by allowing the tool tip coordinate position of a new tool to be set easily when a tool is changed. SOLUTION: Before a tool is changed, the blade tip position of an existing tool 7a is detected by a sensor, and a coordinate position at that time is stored. Next, the blade tip position of a new tool 7b is detected by a sensor and, as the coordinate position of the new tool 7b at that time, the coordinate position of the existing tool stored is set. Thus, when the new tool is positioned at the same blade tip position as that of the existing tool, the coordinate position becomes the same, and the machining of a new work can be started immediately after tool change.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an NC machine tool, and more particularly, to a method of adjusting the coordinate position of a cutting edge of a tool after a tool is replaced.

[0002]

2. Description of the Related Art When mass-producing workpieces having the same specifications by an NC machine tool, when exchanging tools, the coordinate position of the cutting edge of a new tool (new tool) must be accurate. However, in the NC machine tool, it is difficult to attach the new tool to the attachment portion such that the cutting edge coordinate position of the new tool is exactly the same as that of the tool (old tool) used up to that time. Further, by continuing the processing, heat is generated in each part of the NC machine tool, and thereby, the position of the workpiece, the position of the cutting edge of the tool, and the like change. For this reason, it is not possible to obtain high machining accuracy simply by replacing the given dimensions with the coordinate positions of the cutting edge of the NC machine tool and using the tool path.

[0003] Therefore, in the case of the NC machine tool, when a high machining accuracy is required, a method of adjusting the coordinate position of the cutting edge of a new tool by a certain method at the time of tool exchange is adopted. An example of a conventional method of adjusting the coordinate position of the cutting edge after the tool change of the NC machine tool is described below. The first method is to insert a tool offset by performing test cutting using a new tool. In this method, after the tool is changed, trial cutting of a workpiece is performed using a new tool. Then, the actually processed dimensions are measured, and the difference between the measured value (actual dimensions) and the ideal value (ideal dimensions) is determined. This difference is
Since this is an offset value of the actual cutting edge coordinate position with respect to the ideal value of the tool coordinate position, the value based on this difference is used as a correction value, and subsequent NC machining is continued.

[0004] This method is a method that can obtain the highest processing accuracy in the prior art, and is the most commonly employed method. This method is mainly used for finishing.
The second method is a method in which the dimensions of a new tool are measured in advance by a presetter, and the difference between the actual dimensions and the ideal dimensions of the new tool is reflected in the tool offset amount. This method is mainly
It is used for applications such as machining centers.

A third method is a method in which after replacing with a new tool, the coordinate position of the cutting edge is detected by a sensor and the coordinate position of the cutting edge is set in accordance with the initial setting of the coordinate position of the cutting edge of the old tool.

[0006]

The test cutting method of the first method provides high accuracy, but requires trial cutting every time the tool is changed. Therefore, there is a disadvantage that the operation is complicated and the operation rate of the NC machine tool is reduced.
The method using the second presetter requires an extra facility called a presetter and has poor accuracy. Also,
In the second method and the third method, by repeating the processing, NC is caused by the above-mentioned thermal or mechanical cause.
Since the position of each part of the machine tool changes, it is not possible to obtain high machining accuracy simply by replacing the dimension given as the coordinate position of the cutting edge of the new tool with the coordinate position of the cutting edge of the NC machine tool and using the tool path. Can not.

According to the present invention, when mass-producing workpieces having the same specifications by an NC machine tool, the coordinate position of the cutting edge can be automatically and easily set when exchanging a tool. Improve machining accuracy of machine,
And it aims at improving an operation rate.

[0008]

According to the present invention, in order to achieve the above object, the coordinate position of the cutting edge of a new tool is set by the following procedure when changing the tool of an NC machine tool. First, before replacing the tool of the NC machine tool, the position of the cutting edge of the old tool is detected by a sensor, and the value of the coordinate position at this time is stored. Next, after the tool is replaced, the position of the cutting edge of the new tool is detected by the sensor. Then, the stored edge coordinate position of the old tool is set as the edge coordinate position of the new tool at the time of this detection.

When the coordinate position of the cutting edge of the new tool is set by the above procedure when changing the tool of the NC machine tool, when the same coordinate position is designated, the actual position of the cutting edge of the new tool is changed to the actual position of the cutting edge of the old tool. It is the same as the position. Therefore, machining can be continued using the new tool immediately after the tool change. As described above, according to the present invention, it is not necessary to perform test cutting with a new tool or to use a presetter when attaching a new tool. Also, by detecting the position of the cutting edge of the old tool and the new tool with a common sensor, NC
The actual positions of the old tool and the new tool can be matched without being affected by thermal or mechanical changes of the machine tool.

In the present invention, instead of setting the coordinate position of the cutting edge of the old tool as the coordinate position of the cutting edge of the new tool, the coordinate position of the cutting edge when the sensor detects the cutting edge is stored for the old tool and the new tool. In addition, it is possible to determine the difference between the two cutting edge coordinate positions, and use that value as the correction value of the cutting edge coordinate position of the new tool.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an NC lathe will be described with reference to the drawings. FIG. 1 shows a schematic structure of an NC lathe. In FIG. 1, an NC lathe 1 includes a lathe main body 2 and an NC control panel 3. Lathe body 2
Comprises a headstock 4, a chuck 5, a turret 6, a tool 7, a touch sensor 8, a tailstock 9, and a brush 10.
Since the configuration of the lathe body is well known in the art, the description thereof will be limited to a simple one.

FIG. 2 shows the configuration of the NC control panel 3. NC
The control panel 3 includes a central processing unit (CPU) 31, a basic machining program storage unit 32, a display unit 33, a keyboard 34, a new tool edge coordinate position setting unit 35, and a correction value storage unit 36.
Note that the configuration of the NC control panel 3 is also well known in the technical field, and therefore, the description here will be simplified.

The CPU 31 controls the lathe main body 2 in accordance with the basic machining program stored in the basic machining program storage section 32. The correction value storage unit 36 stores an offset value obtained by trial cutting, a correction value due to wear of a tool edge due to continuation of processing, and the like. The new tool cutting edge coordinate position setting unit 35 stores a program for setting the cutting edge coordinate position of a new tool at the time of tool replacement.

Next, the principle of this embodiment will be described with reference to FIGS. In FIG. 3, reference numeral 21 denotes a workpiece. Reference numeral 7 denotes a tool attached to the turret 6, 7a denotes a tool used before replacement (old tool), and 7b denotes a tool used after replacement (new tool). As shown in FIG. 3A, the cutting edge position at the time when the old tool 7a is machining is
It is assumed that it is located at a distance X1 from the main axis. When the new tool 7b is attached at the same turret position, as shown in FIG. 3B, the reference position and the cutting edge position of the turret are significantly different between the old tool 7a and the new tool 7b. The position changes to X2. Here, as shown in FIG. 3C, the cutting edge position of the new tool 7b is set at the same position X1 as the cutting edge position of the old tool 7a, and the coordinate position at this time is when the old tool 7a is at the distance X1. If the coordinate position can be set, the new tool 7b will have the same coordinate position as the old tool 7a when it has the same cutting edge position as the old tool 7a.

In order to realize this, in the present embodiment, the touch sensor 8 detects the cutting edge of the new and old tool 2 in order to place the cutting edge position of the new tool 7b at the same position as the cutting edge position of the old tool 7a. This detection state is shown in FIG. First, old tool 7
Before “a” finishes machining and retreats, the worn cutting edge is detected by the touch sensor 8, and the coordinate position of the old tool 7a at this time is stored. Next, when the same touch sensor 8 detects the cutting edge of the new tool 7b, the cutting edge position at this time becomes the same as the cutting edge position of the old tool 7a. When the stored coordinate of the cutting edge of the old tool 7a is set as the coordinate of the cutting edge of the new tool 7b when the touch sensor 8 detects the cutting edge, the new tool 7a has the cutting edge position and the cutting edge coordinate position. It is the same as the old tool 7a.

Therefore, only by detecting the cutting edge of the new tool 7b and replacing the coordinate position, the workpiece 2 is controlled by the same control as when the old tool 7a is used by using the new tool 7b.
Thus, the same processing can be performed on No. 1 and the processing can be continued without performing trial cutting or the like. Next, a specific operation of the NC lathe will be described with reference to the flowcharts of FIGS. FIG. 5 shows a case where a new machining is started by the NC lathe, that is, a case where the tool is first set and the machining is continued, and FIG. 6 shows a case where the tool is replaced by the tool life and the machining is continued with the new tool. The operation in the case of performing is shown.

The operation when a new machining is started by the NC lathe will be described with reference to FIG. This operation is not different from the conventional operation. Step S11
In, the tool 7 is set on the lathe main body 2 to start a new machining. In step S12, the turret 6 is moved, and the cutting edge of the tool 7 is detected by the touch sensor 8. In the NC control panel 3, at the position where the cutting edge is detected, a coordinate position H (a predetermined coordinate position on the basic machining program) preset as a cutting edge coordinate position of the tool 7 is set.
Set. Thus, thereafter, machining is performed according to the basic machining program stored in the basic machining program storage unit 23 and the cutting edge coordinate position.

In step S13, test cutting is performed on the workpiece 21. Workpiece 2 that has been trial cut
1 is measured and the difference from the ideal size is determined. A predetermined value based on the difference value is input as an offset value h1 from the keyboard 34 and stored in the storage unit 27. In step S14, the NC control panel 3 starts machining according to the basic machining program. At this time, the offset value h is set with respect to the tool edge coordinate position stored as data.
1 is added (or subtracted) to control the tool edge position. Therefore, a high processing accuracy of the workpiece can be obtained.

In step S15, the position of the tool edge is corrected as required. This correction will be described with reference to FIG. As will be described later, when the machining is repeatedly performed, the cutting edge of the tool 7 is worn. As a result, the diameter D of the workpiece 21 increases as the number of processing increases. When it is determined that the position of the cutting edge needs to be adjusted by actually measuring the diameter D, an appropriate correction value h2 is input from the keyboard 25 before exceeding the allowable error. Note that the operation in step S15 can be automatically performed by the NC control panel 3. If no correction is necessary, this step is omitted.

As will be described later, the NC control panel 3 adds (or subtracts) the correction value h2, determines the coordinate position of the tool edge, and proceeds with machining. Since the correction due to tool wear may be performed many times while using the same tool 7, the correction value h2 is accumulated and stored in the storage unit 36. Step S1
In 6, after the end of one machining, it is determined whether or not the tool 7 is damaged. If the tool 7 is damaged, the process returns to step S12, a new tool is set, and trial cutting and the like are started again from the beginning. If the tool 7 has not been damaged, the process proceeds to step S17.

In step S17, it is determined whether or not the tool 7 has reached the time for replacement. This determination is made by an arbitrary method such as a determination based on the number of times of processing or a visual determination of the degree of wear of the tool 7. If the replacement time has not come, the process returns to step S14, and the next workpiece is processed. In the subsequent processing, the NC control panel 21
Controls the cutting edge position of the tool 7 using a coordinate position in which the offset value h1 and the cumulative correction value h2 are added to the coordinate position as data.

When it is time to change the tool 7, the operation proceeds to the operation after the tool change shown in FIG. In step S21 in FIG. 6, before the tool change, the cutting edge of the old tool 7a is detected. For this reason, the turret 6 is moved, and the blade of the old tool 7a whose blade is worn is touched by the touch sensor 8. Step S22
The NC control panel 3 stores the coordinate position at the position where the cutting edge is detected. This coordinate position is obtained by adding the offset value h1 obtained in step S13 to the coordinate position H (predetermined coordinate position in the basic machining program) set in step S12 and the correction value h2 accumulated in step S15.
And H1 (= H + h1 + h2).

In step S23, the old tool 7a is replaced with the new tool 7b. In step S24, the edge of the new tool 7b is touched by the touch sensor 8. Step S25
In the NC control panel 3, the coordinate position H1 (= H + h1 + h2) stored in step S22 is set as the coordinate position at the position where the cutting edge is detected. Further, the correction values h1 and h2 already stored in the storage unit 36 are reset to zero.

Accordingly, when the cutting edge position of the new tool 7b and the worn cutting edge position of the old tool 7a are at the same position, N
The tool edge coordinate position on the C control panel 3 is also the same. Further, in the relationship between the coordinate position as data and the tool edge position, the coordinate position of the new tool 7b is obtained by adding the correction values h1 and h2 when the old tool 7a is used. Therefore, even after the tool change, the same machining as the machining with the old tool 7a can be continued with the new tool 7b only by controlling based on the coordinate position of the data without performing trial cutting.

Since the same touch sensor 8 detects the position of the cutting edge of the old tool 7a and the position of the cutting edge of the new tool 7b, thermal or mechanical changes in the lathe body 2 cause the touch sensor 8 and the turret to change. Even if the positional relationship with the tool 6 is shifted, the cutting edge positions of the new and old tools 7a and 7b are exactly the same without being affected by them.
In step S26, the correction value storage unit 36 stores a predetermined value based on the difference between the actual processing dimension and the ideal dimension of the workpiece processed immediately before the tool change as a new correction value h3.
Step S26 can be omitted.

In step 27, using the new tool 7b,
Machining according to the basic machining program is started. At this time, a correction value h2 described later and a correction value h3 set in step S26 are added (or subtracted) to the tool edge coordinate position stored as data, and the tool edge position is controlled. Thus, from the start of machining of the new tool 7b, machining can be performed after performing a correction approaching the ideal size.

In step S28, the position of the tool edge is corrected as required. This correction is the same as in step S15 described above. The position of the blade edge is adjusted according to the wear of the blade edge of the tool 7, and the adjusted value is stored as a correction value h2 and a cumulative value is stored. In step S29, it is determined whether or not the tool 7 is damaged, as in step S16 described above. Here, when it is determined that the tool 7 has been damaged, the process returns to step S12, and a new tool is set and trial cutting is performed again from the beginning. If the tool 7 has not been damaged, the process proceeds to step S30.

In step S30, the aforementioned step S17
Similarly to the above, it is determined whether or not the tool replacement time has come.
If the replacement time has not come, the process returns to step S27, and the next workpiece is processed. In the subsequent processing, the NC control panel 3 controls the cutting edge position of the tool 7 by using the coordinate position in which the correction value h3 and the cumulative correction value h2 in step S28 are added to the coordinate position as data. When it is time to replace the tool 7, the process proceeds to step S21.

In the next step S21, the tool 7 used so far is treated as the old tool 7a. Thereafter, operations similar to those described above are repeated, and processing is performed. As is clear from the above description, according to the present embodiment, it is not necessary to perform trial cutting or the like on the new tool 7b at the time of tool replacement, and machining with the new tool 7b can be performed immediately. At this time, even if there is a thermal or mechanical change in the lathe main body 2, processing can be continued with the same processing accuracy as when the old tool 7a was used, without being affected by the change.

Here, the brush 10 of FIG. 1 will be described. The cutting edge of the new and old tools 7 is detected by the touch sensor 8, and in order to improve the accuracy, a brush 10 is provided for removing constituent cutting edges and dust that may be attached to the cutting edges. FIG. 8 shows an example of the brush 10. 8, reference numeral 10 denotes a brush, which is rotated by a motor (not shown). Reference numeral 11 denotes a nozzle for performing air blowing. Therefore, before detecting the cutting edge of the tool 7, the turret 6 is moved, and the cutting edge of the tool 7 is applied to the rotating brush 10 to remove dust and the like. Further, compressed air is blown from the nozzle 11 to the cutting edge to blow off dust and the like. Accordingly, accurate edge detection by the touch sensor 8 can be performed.

The embodiment of the present invention has been described above. However, the present invention can be variously modified within the scope stored in each claim. FIG. 9 shows a flowchart in a case where the operation at the time of tool change of FIG. 4 is partially changed. Hereinafter, differences from FIG. 4 will be described. In this example, up to step S24, FIG.
The operation is performed in the same manner as in FIG. When the edge of the new tool 7b is touched by the touch sensor 8 in step S24, the coordinate position H2 at that time is stored in step S35.

In step S36, the difference between the coordinate position H1 of the old tool 7a and the coordinate position H2 of the new tool 7 stored in step 22 is calculated. Then, the difference is stored in the storage unit 27 as the correction value h4. The already stored correction values h1 and h2 are stored without being reset. The description of step S26 is omitted.

At the time of machining in step S27, N
The C control panel 3 controls the tool edge position in consideration of the correction values h1, h2, h3, and h4 with respect to the tool edge coordinate position stored as data. The correction value h2 in step S28 is a value obtained by accumulating the correction value for the old tool 7a and the correction value for the new tool 7b.

The same operation and effect as the operations in the flowcharts shown in FIGS. 5 and 6 can be obtained by the operation in the flowchart shown in FIG. As another embodiment of the present invention, in the above description, only the outer diameter cutting of the NC lathe, that is, the inheritance of the cutting edge coordinate position on the X axis is described, but the inheritance of the cutting edge coordinate position is similarly performed on the other axes. It can be carried out. Therefore, as shown in FIG. 4 described above, a touch sensor 8 having a structure capable of detecting the position of the cutting edge in each axis is used.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an NC control panel to which the present invention is applied.

FIG. 2 is a diagram showing a configuration of an NC control panel of FIG. 1;

FIG. 3 illustrates the principle of the embodiment of the present invention (part 1).

FIG. 4 illustrates the principle of the embodiment of the present invention (part 2).

FIG. 5 is a flowchart (part 1) illustrating the operation of the embodiment of the present invention.

FIG. 6 is a flowchart (part 2) illustrating the operation of the embodiment of the present invention.

FIG. 7 is a view for explaining a correction value h2 in the embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of the brush of FIG. 1;

FIG. 9 is a flowchart showing a modification of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... NC control board 2 ... Lathe main body 3 ... NC control board 4 ... Headstock 5 ... Chuck 6 ... Turret 7 ... Tool 7a ... Old tool 7b ... New tool 8 ... Touch sensor 9 ... Tailstock 10 ... Brush 11 ... Nozzle 21 Workpiece 31 CPU 32 Basic machining program storage unit 33 Display unit 34 Keyboard 35 New tool tip coordinate position setting unit 36 Correction value storage unit

Claims (4)

[Claims] 1. Before exchanging a tool of an NC machine tool, a step of detecting a cutting edge position of an old tool used so far by a sensor and storing a value of a coordinate position at this time, and exchanging the tool. Detecting the position of the cutting edge of a new tool to be subsequently used by the sensor, and setting the stored cutting edge coordinate position of the old tool as the cutting edge coordinate position of the new tool at this time. For setting the cutting edge position when changing tools. 2. Prior to exchanging a tool of an NC machine tool, a step of detecting a cutting edge position of an old tool used so far by a sensor and storing a coordinate position value at this time, and exchanging the tool. Later, the edge position of the new tool to be used thereafter is detected by a sensor, and the value of the coordinate position at this time is stored.The difference between the stored edge coordinate position of the old tool and the coordinate position of the new tool is calculated. And storing the difference value as a correction value of the coordinate position of the cutting edge of the new tool. 3. A tool change of an NC machine tool according to claim 1, wherein a value based on a difference between an actual size and an ideal size of a workpiece finally processed by the old tool is stored as a correction value. Cutting edge position setting method. 4. An NC machine tool for executing the method for setting a cutting edge position when a tool of the NC machine tool is changed according to claim 1, wherein the brush for cleaning the cutting edge of the tool is provided. NC machine tool equipped.