JP6946104B2 - Control device and control method for tool cutting direction in machine tools - Google Patents

Description

The present invention relates to a control device and a control method for controlling the cutting direction of a tool with respect to a work in turning using a machine tool.

When turning using a machine tool, vibration called chatter vibration often occurs when the rigidity of the work is low or the rigidity of the tool is low. This chatter vibration causes a periodic pattern called a chatter mark on the machined surface, which causes deterioration of the finished surface properties and processing accuracy. Examples of means for suppressing such chatter vibration include improvement of work rigidity by changing the work fixing means, improvement of tool rigidity by changing the design of the tool post, reduction of the depth of cut, and the like.

However, it is not easy to improve the rigidity by changing the work fixing means or the design of the tool post because it requires a high degree of expertise, time and cost to examine the means and create the parts. In addition, although it is easy to reduce the cutting amount, it leads to a decrease in production efficiency.
Therefore, Patent Document 1 describes an approach angle at which the absolute value of the back component force applied to the work by the tool when turning is performed according to the cutting amount data of the machining program is equal to or less than a specified value (preferably 0). An invention is disclosed in which chatter vibration is suppressed and turning accuracy is improved by calculating and executing turning.

Japanese Patent No. 5766895

In the invention of Patent Document 1, when the insert of the round piece tip is used as the turning tool, the back component force does not change even if the approach angle is changed, so that the effect of suppressing chatter vibration cannot be expected. When using a wiper tip, changing the approach angle makes it impossible to obtain the desired surface roughness. Furthermore, it may not be applicable depending on the processing, such as the approach angle cannot be changed by grooving.
On the other hand, regardless of the turning tool, in machining with a small depth of cut, the back component force hardly changes even if the approach angle is changed, so that the effect of suppressing chatter vibration cannot be expected.
Then, since the turret is swiveled around the B axis here, when machining a stepped work, the turret may interfere with the work and the approach angle cannot be changed.

Therefore, the present invention is a control device for a tool cutting direction in a machine tool, which can easily obtain an effect of suppressing chatter vibration regardless of the turning tool, the size of the cutting amount, etc., and without lowering the production efficiency. And the purpose is to provide a control method.

In order to achieve the above object, the invention according to claim 1 includes three linear axes orthogonal to each other, a tool rotation axis capable of changing and holding a tool rotation angle position, and a work rotation axis for rotating a work. , When performing turning work in which the tool is cut into the work from the direction orthogonal to the work rotation axis and sent in the axial direction of the work rotation axis , at least two straight axes and the tool rotation axis are controlled to the tool work. It is a device provided in a machine tool equipped with a cutting direction control means for changing the cutting direction of the tool, and controls the cutting direction of the tool.
A history of the vibration detection means for measuring the vibration of the tool and / or the work, the setting value of the cut direction changed by the cutting direction control means, and the magnitude of the vibration measured by the vibration detecting means. The cutting direction control means positions the tool in the most appropriate insertion direction detected by the most appropriate insertion direction detecting means. It is characterized by doing.
The invention according to claim 2 is characterized in that, in the configuration of claim 1, the cutting direction control means continuously changes the cutting direction.
The invention according to claim 3 includes, in the configuration of claim 1 or 2, a machining load monitoring means for monitoring the load on the work rotation shaft, and the most appropriate loading direction detecting means is used when detecting the most appropriate loading direction. When the load obtained by the machining load monitoring means differs from the value at the start of changing the cutting direction by a predetermined ratio or a predetermined value or more, the history of the magnitude of vibration measured in that case is excluded. ..
In order to achieve the above object, the invention according to claim 4 comprises three linear axes orthogonal to each other, a tool rotation axis capable of changing and holding a tool rotation angle position, and a work rotation axis for rotating a work. , When performing turning by cutting the tool into the work from the direction perpendicular to the work rotation axis and sending it in the axial direction of the work rotation axis , control at least two straight axes and the tool rotation axis to the tool work. A method of controlling the cutting direction of a tool in a machine tool provided with a cutting direction controlling means for changing the cutting direction of the tool and a vibration detecting means for measuring the vibration of the tool and / or the workpiece.
A cutting direction changing step in which the cutting direction is changed by the cutting direction control means and the set value of the changed cutting direction and the magnitude of vibration measured by the vibration detecting means are stored.
From the history of the set value and the magnitude of vibration, the most appropriate insertion direction detection step that detects the most appropriate insertion direction that minimizes vibration, and the most appropriate insertion direction detection step.
It is characterized in that the cutting direction control means executes a positioning step of positioning the tool in the detected most appropriate cutting direction.

According to the present invention, it is possible to automatically search for the most appropriate insertion direction during turning and position the tool. Therefore, chatter vibration can be easily suppressed. Further, since only the cutting direction is changed, the production efficiency is not lowered, and the effect of suppressing chatter vibration can always be obtained regardless of the type of tool and the size of the cutting amount.

It is a block diagram of the control device of the tool cutting direction of a machine tool. It is a flowchart of the control method of a tool cutting direction. It is explanatory drawing which shows the change state of the cutting direction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing an example of a control device for a tool cutting direction of a machine tool. In the figure, reference numeral 1 denotes a machine tool having a well-known configuration, in which a spindle 3 as a work rotation axis is rotatably supported on the bed 2, and a table 5 fixed to the spindle 3 by a spindle motor 4 is provided. It is rotatable. A column 6 is erected on the bed 2 so as to be slidable back and forth along the bed 2, and a saddle 8 can be slid left and right along a cross slide 7 provided so as to be movable up and down on the front surface of the column 6. It has become. A tool post 9 is fixed to the saddle 8, and an M axis 10 as a tool rotation axis is rotatably supported on the tool post 9, so that the tool 11 can be attached to the M axis 10. The M-axis 10 can be rotated and the rotation position can be determined by a well-known configuration.

Therefore, in this machine tool 1, by controlling the three orthogonal feed axes that drive the column 6, the cross slide 7, and the saddle 8, the tool 11 is used for the work 12 that is mounted on the table 5 and rotates. Can be turned in the radial direction and in the rotation axis direction.

Reference numeral 13 denotes a control device in the tool cutting direction, which is provided in the NC device here. The control device 13 holds an input unit 14 for inputting a machining program, a search start command for the most appropriate insertion direction, which will be described later, and numerical control information related to control of the spindle motor 4 and the feed shaft, and inputs the numerical control information to the input unit 14. The numerical control information execution unit 15 that outputs numerical control information based on the command, and the spindle control unit 17 that controls the spindle motor 4 and the feed shaft are controlled based on the numerical control information from the numerical control information execution unit 15. A cut direction control unit 16 is provided as a cut direction control means for controlling the feed axis control unit 18 and the M axis control unit 19 for controlling the M axis 10 to determine the cut direction. Further, a machining load monitoring unit 20 is provided as a machining load monitoring means for calculating an average value of the machining load at a predetermined sampling cycle using the torque command value held by the spindle control unit 17.

Further, the tool post 9 is provided with a vibration sensor 21 as a vibration detecting means, and the control device 13 is provided with a vibration amount calculation unit 22 that Fourier-converts the vibration waveform measured by the vibration sensor 21 to calculate the vibration amplitude. It is provided. Reference numeral 23 denotes a storage unit, which is calculated by the processing program and other commands input via the input unit 14, the numerical control information held by the numerical control information execution unit 15, and the processing load monitoring unit 20. The average value of the processing load, the vibration amplitude calculated by the vibration amount calculation unit 22, and the like can be stored.
Reference numeral 24 denotes the most appropriate insertion direction detection unit as the most appropriate insertion direction detection means, and the most appropriate insertion direction detection unit 24 is the angular position of the M axis 10 stored in the storage unit 23 and the vibration of the tool post 9. With reference to the amplitude value, the cutting direction in which the vibration amplitude value becomes the minimum is detected and output to the numerical control information execution unit 15.

The method of controlling the tool cutting direction by the control device 13 configured as described above will be described with reference to the flowchart of FIG.
First, during turning, when the operator inputs a search start command for the most appropriate insertion direction to the numerical control information execution unit 15 via the input unit 14 in S1, the cutting direction control unit 16 sends the feed shaft in S2. Through the control unit 18 and the M-axis control unit 19, the circular motion of the feed axis of the saddle 8 and the feed axis of the column 6 and the rotational motion of the M-axis 10 are synchronized, and as shown in FIG. With the cutting edge position of the tool 11 always perpendicular to the circumferential surface of the work 12 and the set value of the cutting amount being constant, the cutting direction of the tool 11 is continuously set to a predetermined value at a predetermined speed. Change (cut direction change step). FIG. 3 shows a case where the tool is circularly moved from the initial tool position A in which the cutting direction is D1 to the moving position B in which the cutting direction is D2. The arrow S is the rotation direction of the work 12.

At this time, the storage unit 23 stores the angular position of the M axis 10 indicating the cutting direction held by the numerical control information execution unit 15 and the value of the vibration amplitude held by the vibration amount calculation unit 22 in a predetermined sampling cycle. do.
Next, in S3, the most appropriate insertion direction detection unit 24 refers to the angular position of the M axis 10 stored in the storage unit 23 and the value of the vibration amplitude of the tool post 9, and the value of the vibration amplitude becomes the minimum. Detect the most appropriate loading direction (most suitable loading direction detection step).
However, when the average value of the machining load calculated by the machining load monitoring unit 20 changes by a predetermined ratio or more from the value at the start of changing the cutting direction, or when a difference of a predetermined value or more occurs. , The most appropriate penetration direction detection unit 24 detects the most appropriate penetration direction by excluding the data of the vibration amplitude corresponding to the change portion or the difference portion. This is to eliminate a temporary change in vibration amplitude caused by a change in the cutting mode during control depending on the shape of the work such as a groove.

Then, in S4, the feed shaft of the saddle 8 and the column 6 are arranged so that the cutting direction control unit 16 is in the most appropriate insertion direction detected by the most appropriate insertion direction detection unit 24 via the numerical control information execution unit 15. The arc motion of the feed shaft and the rotational motion of the M axis 10 are synchronized to position the tool 11 in the most appropriate insertion direction (positioning step). When the machining is completed in S5, the control of the tool cutting direction is completed.

As described above, according to the tool cutting direction control device 13 and the control method of the above-described embodiment, when the search start command of the most appropriate cutting direction is input to the input unit 14, the cutting direction control unit 16 controls the tool 11. The cutting direction is changed, and the angular position of the M axis 10 (set value of the cutting direction) indicating the changed cutting direction and the value of the vibration amplitude held by the vibration amount calculation unit 22 (vibration magnitude) are changed. From the history of the angular position of the M-axis 10 and the value of the vibration amplitude, the most appropriate insertion direction detection unit 24 detects the most appropriate insertion direction that minimizes vibration, and the tool is used in the detected most appropriate insertion direction. Since the 11 is positioned, the tool 11 can be positioned by automatically searching for the most appropriate insertion direction during the turning process. Therefore, chatter vibration can be easily suppressed. Further, since only the cutting direction is changed, the production efficiency is not lowered, and the chatter vibration suppressing effect can always be obtained regardless of the type of the tool 11 and the size of the cutting amount.

The control device and the control method according to the present invention are not limited to the above-described embodiment, and the configuration and the like related to the control device and the machine tool are appropriately changed as necessary without departing from the gist of the present invention. can do.
For example, in the above embodiment, the vibration of the tool post is measured by a vibration sensor in order to indirectly detect the vibration of the tool, and the cutting direction is controlled so that the vibration of the tool post is minimized. The vibration may be indirectly measured by a vibration sensor provided on the bed, and the most appropriate insertion direction may be detected based on the vibration of the work. Further, the most appropriate insertion direction may be detected based on the vibration between the tool side and the work side. In this case, it is conceivable to compare the ratio of the vibration amplitude measured by each vibration sensor to the predetermined value and control the cutting direction so that the vibration having the larger value is minimized. Further, the operator may select and command which vibration between the tool and the workpiece should be minimized.

Further, in the above embodiment, a machining load monitoring unit is provided to calculate the average value of the machining load in a predetermined sampling cycle, and when the average value of the machining load changes by a predetermined ratio or more, the most appropriate loading direction is detected. Although the vibration amplitude data is ignored at the time, the machining load monitoring unit can be omitted and the most appropriate loading direction can be detected by referring to all the vibration amplitude data.

In the above embodiment, when searching for the most appropriate cutting direction, the cutting direction control unit continuously changes the cutting direction, but the cutting direction is intermittently changed at predetermined angles to vibrate. Amplitude data may be acquired and the most appropriate loading direction may be detected.
In addition, the configuration of the machine tool is not limited to the above-mentioned form, and the present invention can be applied to a horizontal shape as well as a vertical shape.

1 ... Machine tool, 2 ... Bed, 3 ... Spindle, 4 ... Spindle motor, 5 ... Table, 6 ... Column, 8 ... Saddle, 9 ... Tool stand, 10 ... M axis, 11・ ・ Tool, 12 ・ ・ Work, 13 ・ ・ Control device, 14 ・ ・ Input unit, 15 ・ ・ Numerical control information execution unit, 16 ・ ・ Cutting direction control unit, 17 ・ ・ Spindle control unit, 18 ・ ・ Feed Axis control unit, 19 ... M axis control unit, 20 ... machining load monitoring unit, 21 ... vibration sensor, 22 ... vibration amount calculation unit, 23 ... storage unit, 24 ... most appropriate insertion direction detection unit, D1, D2 ... Cut direction.

Claims (4)

Three straight axes orthogonal to each other, a tool rotation axis capable of changing and holding the rotation angle position of the tool, a work rotation axis for rotating the work, and cutting the tool into the work from a direction orthogonal to the work rotation axis. A cut that changes the cutting direction of the tool into the work by controlling at least two of the straight shafts and the tool rotating shaft when performing a turning process in which the work is inserted and sent in the axial direction of the work rotation shaft. A device provided on a machine tool provided with a direction control means and for controlling the cutting direction of the tool.
A vibration detecting means for measuring the vibration of the tool and / or the work, and
The cutting direction is changed by the cutting direction control means, and the most appropriate cutting direction that minimizes the vibration is determined from the history of the changed cutting direction setting value and the vibration magnitude measured by the vibration detecting means. Equipped with the most appropriate built-in direction detection means for detection,
The cutting direction control means is a control device for a tool cutting direction in a machine tool, characterized in that the tool is positioned in the most appropriate cutting direction detected by the most suitable cutting direction detecting means. The control device for a tool cutting direction in a machine tool according to claim 1, wherein the cutting direction controlling means continuously changes the cutting direction. The machining load monitoring means for monitoring the load on the work rotation shaft is provided, and when the most appropriate loading direction detecting means detects the most appropriate loading direction, the load obtained by the machining load monitoring means starts changing the cutting direction. The tool cutting in the machine tool according to claim 1 or 2, wherein when the value differs from the time value by a predetermined ratio or a predetermined value or more, the history of the magnitude of the vibration measured in that case is excluded. Directional control device. Three straight axes orthogonal to each other, a tool rotation axis capable of changing and holding the rotation angle position of the tool, a work rotation axis for rotating the work, and cutting the tool into the work from a direction orthogonal to the work rotation axis. A cut that changes the cutting direction of the tool into the work by controlling at least two of the straight shafts and the tool rotation shaft when performing a turning process in which the work is inserted and sent in the axial direction of the work rotation shaft. A method of controlling the cutting direction of the tool in a machine tool including a direction controlling means and a vibration detecting means for measuring the vibration of the tool and / or the work.
A cutting direction changing step in which the cutting direction is changed by the cutting direction control means and the set value of the changed cutting direction and the magnitude of vibration measured by the vibration detecting means are stored.
From the history of the set value and the magnitude of the vibration, the most appropriate insertion direction detection step for detecting the most appropriate insertion direction in which the vibration is minimized, and the most appropriate insertion direction detection step.
A method for controlling a tool cutting direction in a machine tool, which comprises executing a positioning step of positioning the tool in the detected most appropriate cutting direction by the cutting direction controlling means.

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