JP6735309B2 - Machine tools, cutting methods, and cutting programs - Google Patents

Description

The present disclosure relates to a technique for suppressing the occurrence of reproduction chatter vibration that may occur in a machine tool.

When cutting a workpiece with a machine tool, the cutting edge of the tool may vibrate. Such vibration is called reproduction chatter vibration. When the play chatter vibration occurs, the cutting accuracy of the work is reduced.

The reproduction chatter vibration is a vibration that occurs when the relationship between the vibration frequency of the tool and the cutting width of the work by the tool satisfies a predetermined condition.

As documents disclosing a technique for suppressing reproduction chatter vibration, there are JP-A-2005-74568 (Patent Document 1), JP-A-2013-43240 (Patent Document 2), and JP-A-2012-183596. (Patent Document 3). The machine tools disclosed in Patent Documents 1 to 3 have prepared a plurality of stability lobes that define a stable range of cutting conditions in which regenerated chatter vibration does not occur and an unstable range of cutting conditions in which regenerated chatter vibration occurs. , It is disclosed that the reproduction chatter vibration is suppressed by keeping the cutting conditions within the overlapping range of the safety range of each stable lobe.

JP, 2005-74568, A JP, 2013-43240, A JP2012-183596A

However, the cutting condition in which the regenerated chatter vibration is generated varies depending on the cutting direction. Therefore, in order to more reliably suppress the regenerated chatter vibration, it is necessary to consider the cutting direction. Since the machine tools disclosed in Patent Documents 1 to 4 do not use the stable lobes corresponding to the cutting direction, regenerative chatter vibration may occur depending on the cutting direction.

The present disclosure has been made to solve the above-described problems, and an object of a certain aspect is to provide a machine tool capable of suppressing the occurrence of regenerative chatter vibration regardless of the cutting direction. is there. An object in another aspect is to provide a cutting method capable of suppressing the occurrence of regenerative chatter vibration regardless of the cutting direction. An object in another aspect is to provide a cutting program capable of suppressing the occurrence of regenerative chatter vibration regardless of the cutting direction.

In an example of the present disclosure, a machine tool includes a tool for cutting a work, a spindle for rotating the work or the tool, a drive unit for driving the spindle, and a cutting of the work by the tool. A storage device for storing a stable range that defines a range of cutting conditions in which chatter vibration does not occur in the relationship between the width and the rotation speed of the spindle, in association with each cutting direction of the tool with respect to the workpiece. A control device for controlling the cutting direction of the tool with respect to the work by controlling the driving direction of the spindle by the driving unit. The control device sets the control parameter for at least one of the cutting width of the workpiece by the tool and the rotational speed of the spindle so that the cutting conditions fall within the stable range corresponding to the current cutting direction. Machine Tools.

In an example of the present disclosure, the control device sets the control parameter such that the cutting condition falls within an overlapping range of a plurality of stable ranges stored in the storage device.

In an example of the present disclosure, the control device does not change the control parameter according to the cutting direction of the tool with respect to the work.

In one example of the present disclosure, each time the control device changes the cutting direction of the tool with respect to the work, a stable range corresponding to the changed cutting direction is selected from a plurality of stable ranges stored in the storage device. Is selected, and the control parameter is set so that it falls within the stable range.

In an example of the present disclosure, the control device controls the control parameter so that the cut width becomes maximum within the selected stable range.

In one example of the present disclosure, the control device responds to the changed cutting direction from among a plurality of stable ranges stored in the storage device based on changing the cutting direction of the tool with respect to the work. A predetermined number of stable ranges to be selected are selected, and the control parameters are set so that they fall within the overlapping range of the selected predetermined number of stable ranges.

In another example of the present disclosure, a machine tool cutting method is provided. The machine tool includes a tool for cutting a work, a spindle for rotating the work or the tool, and a drive unit for driving the spindle. The cutting method includes a step of acquiring a plurality of stable ranges that define a range of cutting conditions in which chatter vibration does not occur in the relationship between the cutting width of the workpiece by the tool and the rotation speed of the spindle. Each of the plurality of stable ranges is associated with each cutting direction of the tool with respect to the work. The cutting method further corresponds to the step of controlling the cutting direction of the tool with respect to the workpiece by controlling the driving direction of the spindle by the driving unit, and the current cutting direction within the plurality of stable ranges. A step of setting a control parameter relating to at least one of a cutting width of the work by the tool and a rotation speed of the spindle so that the cutting condition falls within the stable range.

In another example of the present disclosure, a cutting program executed by a machine tool is provided. The machine tool includes a tool for cutting a work, a spindle for rotating the work or the tool, and a drive unit for driving the spindle. The cutting program acquires, in the machine tool, a plurality of stable ranges that define a range of cutting conditions in which chatter vibration does not occur in the relationship between the cutting width of the workpiece by the tool and the rotation speed of the spindle. Run the step. Each of the plurality of stable ranges is associated with each cutting direction of the tool with respect to the work. The cutting program further includes: a step of controlling the cutting direction of the tool with respect to the workpiece by controlling the driving direction of the spindle by the driving unit in the machine tool; The step of setting a control parameter relating to at least one of the cutting width of the work by the tool and the rotation speed of the spindle is executed so that the cutting condition falls within the stable range corresponding to the cutting direction.

In a certain aspect, it is possible to suppress the occurrence of reproduction chatter vibration regardless of the cutting direction.

The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the invention, which is understood in connection with the accompanying drawings.

It is a figure showing an example of a machine tool according to an embodiment. It is a figure which shows an example of the cutting conditions which a reproduction chatter vibration is easy to produce. It is a figure which shows an example of the cutting conditions which reproduction chatter vibration is hard to produce. It is a figure which shows the cutting aspect of a workpiece. FIG. 5 is a diagram showing a stable range in which regenerative chatter vibration does not occur and an unstable range in which regenerative chatter vibration occurs in the relationship between the spindle rotational speed and the work cut width. It is a figure which shows the cutting aspect of the workpiece|work with a tool. It is a figure which shows the relationship between a workpiece|work and a cutting direction. It is a figure which shows the result of having investigated the maximum cutting width which does not generate|occur|produce reproduction chatter vibration for every cutting direction, fixing a main shaft rotation speed. It is a figure which shows the result of having investigated the maximum cutting width which does not generate|occur|produce reproduction chatter vibration for every cutting direction, after optimizing the spindle speed. It is a figure which shows the stable lobe obtained from the experimental result for every cutting direction. It is a figure which shows the cutting mode according to the specific example 1. It is a figure which shows the cutting aspect according to the specific example 2. It is a figure which shows the cutting mode according to the specific example 3. It is a flow chart showing a generating process of a stable lobe corresponding to each cutting direction. 7 is a flowchart showing a cutting process using the generated stable lobe. 7 is a flowchart showing a cutting process using the generated stable lobe. FIG. 3 is a block diagram showing a main hardware configuration of the machine tool according to the embodiment.

Each embodiment according to the present invention will be described below with reference to the drawings. In the following description, the same parts and components are designated by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated. It should be noted that the embodiments and the modifications described below may be appropriately combined selectively.

<A. Configuration of machine tool 100>
The configuration of the machine tool 100 will be described with reference to FIG. FIG. 1 is a diagram illustrating an example of the machine tool 100.

FIG. 1 shows a machine tool 100 as a machining center. The machine tool 100 as a machining center will be described below, but the machine tool 100 is not limited to a machining center. For example, the machine tool 100 may be a lathe, or may be another cutting machine or grinding machine. Further, the machine tool 100 may be a vertical machining center in which the tool is mounted vertically, or a horizontal machining center in which the tool is mounted horizontally.

As shown in FIG. 1, the machine tool 100 has a spindle head 21. The spindle head 21 is composed of a spindle 22 and a housing 23. The main shaft 22 is arranged inside the housing 23. A tool for processing a workpiece, which is a workpiece, is mounted on the spindle 22. In the example of FIG. 1, a tool 32 as an end mill is attached to the spindle 22.

The spindle head 21 is configured to be drivable along the ball screw 25 in the Z-axis direction. A drive mechanism such as a servo motor is connected to the ball screw 25. The drive mechanism moves the spindle head 21 by driving the ball screw 25, and moves the spindle head 21 to an arbitrary position in the Z-axis direction.

A drive mechanism such as a servo motor is connected to the main shaft 22. The drive mechanism rotationally drives the main shaft 22 about a central axis AX1 parallel to the Z-axis direction (vertical direction). As a result, the tool 32 mounted on the spindle 22 rotates about the central axis AX1 as the spindle 22 rotates. When the machine tool 100 is a lathe, a work is mounted on the spindle 22. In this case, the work mounted on the spindle 22 rotates as the spindle 22 rotates.

The machine tool 100 further includes an automatic tool changer (ATC) 30. The automatic tool changer 30 is composed of a magazine 31, a pushing mechanism 33, and an arm 36. The magazine 31 is a device for accommodating various tools 32 for processing a work. The magazine 31 includes a plurality of tool holders 34 and a sprocket 35.

The tool holding unit 34 is configured to hold various tools 32. The plurality of tool holding portions 34 are annularly arranged around the sprocket 35. The sprocket 35 is driven by a motor so as to be rotatable about a central axis AX2 parallel to the X axis. With the rotation of the sprocket 35, the plurality of tool holding portions 34 rotate around the central axis AX2.

The automatic tool changer 30 extracts the tool 32 to be mounted from the magazine 31 and mounts the tool 32 on the spindle 22 based on the instruction to replace the tool. More specifically, the automatic tool changer 30 moves the tool holder 34 holding the target tool 32 in front of the pushing mechanism 33. Next, the push-out mechanism 33 pushes out the target tool 32 toward the exchange position by the arm 36. After that, the arm 36 pulls out the target tool 32 from the tool holding portion 34 and pulls out the currently mounted tool 32 from the spindle 22. Thereafter, the arm 36 makes a half rotation while holding these tools 32, mounts the target tool 32 on the spindle 22, and stores the original tool 32 in the tool holder 34. As a result, the tool 32 is replaced.

The machine tool 100 further includes a moving mechanism 50 for moving the workpiece to be processed on the XY plane. The moving mechanism 50 includes guides 51 and 53, ball screws 52 and 54, and a table 55 (work holding unit) for holding a work.

The guide 51 is installed parallel to the Y axis. The guide 53 is provided on the guide 51 and is installed parallel to the X axis. The guide 53 is configured to be driven along the guide 51. The table 55 is provided on the guide 53 and can be driven along the guide 53.

A drive mechanism such as a servomotor is connected to the ball screw 52. The drive mechanism moves the guide 53 along the guide 51 by driving the ball screw 52, and moves the guide 53 to an arbitrary position in the Y-axis direction. Similarly, a drive mechanism such as a servo motor is also connected to the ball screw 54. The drive mechanism drives the ball screw 54 to move the table 55 along the guide 53, and moves the table 55 to an arbitrary position in the X-axis direction. That is, the machine tool 100 moves the table 55 to an arbitrary position on the XY plane by cooperatively controlling the drive mechanisms connected to the ball screws 52 and 54, respectively. As a result, the machine tool 100 can perform machining while moving the work held on the table 55 on the XY plane.

The housing 43 is provided with an acceleration sensor 110 for detecting the vibration frequency of the spindle 22 or the tool 32. Preferably, a plurality of acceleration sensors 110 are provided in the housing 43, and each acceleration sensor 110 detects vibration of the spindle 22 or the tool 32 in different directions (for example, X, Y, Z directions). The sensor for detecting the vibration frequency is not limited to the acceleration sensor 110, and any sensor capable of detecting the vibration frequency of the tool 32 or the spindle 22 may be used.

<B. Principle of reproduction chatter vibration>
When the workpiece is machined by the machine tool 100, a play chatter vibration in which the cutting edge of the tool 32 vibrates slightly may occur. The reproduction chatter vibration is a vibration that occurs when the relationship between the vibration frequency of the tool 32 and the cutting width of the work by the tool 32 satisfies a predetermined condition.

Machine tool 100 according to the present embodiment suppresses the occurrence of reproduction chatter vibration regardless of the cutting direction by setting control parameters based on a plurality of stable lobes corresponding to the cutting direction. In order to facilitate understanding of this control processing, first, the principle of occurrence of reproduction chatter vibration will be described with reference to FIGS.

FIG. 2 is a diagram showing an example of cutting conditions in which regenerative chatter vibration is likely to occur. More specifically, FIG. 2(A) shows a cutting trace on the work during the previous cutting. FIG. 2B shows the vibration frequency of the tool 32 during the cutting this time. FIG. 2C shows the cutting thickness of the work by the tool 32 at the time of this cutting.

The tool 32 cuts the work by repeatedly cutting the work while rotating. The tool 32 vibrates during cutting of the work, and as shown in FIG. 2(A), the cutting surface of the work is uneven.

When the tool 32 next cuts a work, the cutting trace at the time of the previous cutting and the vibration frequency of the tool 32 at the time of this cutting may deviate. If this deviation is represented by “φ”, the deviation φ is π/4 (=90 degrees) in the examples of FIGS. 2A and 2B. When such a deviation occurs, the cutting thickness of the work changes depending on the cutting position. FIG. 2C shows the variation of the cutting thickness when the deviation of φ=π/4 occurs. When the cutting thickness changes, the force that the tool 32 receives from the work during cutting changes, and regenerative chatter vibration easily occurs. In particular, reproduction chatter vibration is most likely to occur when φ=π/4.

FIG. 3 is a diagram showing an example of cutting conditions in which reproduction chatter vibration is unlikely to occur. More specifically, FIG. 3(A) shows a cutting trace on the work during the previous cutting. FIG. 3B shows the vibration frequency of the tool 32 during the cutting this time. FIG. 3C shows the cutting thickness of the work by the tool 32 at the time of this cutting.

In the example of FIG. 3A and FIG. 3B, the vibration frequency of the tool 32 overlaps with the cutting trace during the previous cutting. In this case, the deviation "φ" becomes 0 and the cutting thickness of the work becomes constant. Therefore, the force that the tool 32 receives from the work during cutting becomes constant, and regenerative chatter vibration hardly occurs.

Therefore, when the rotational speed of the main shaft 22 is adjusted so that the deviation “φ” approaches 0, the reproduction chatter vibration is less likely to occur. On the other hand, when the rotational speed of the main shaft 22 is adjusted so that the deviation “φ” approaches π/4, reproduction chatter vibration is likely to occur.

Typically, when “k” shown in the following formula (1) becomes an integer, the deviation “φ” becomes 0.

(Equation 1)
_{k = 60 · f c / (} n 0 · N) ··· (1)
“K” shown in the equation (1) is the wave number of the cutting surface caused by the vibration of the tool 32 from the time when the first blade of the tool 32 contacts the work to the time when the second blade contacts the work. Represent. “F _c ”represents the vibration frequency of the main shaft 22. “N” represents the number of blades of the tool 32. “N ₀ ”represents the rotation speed of the main shaft 22. The rotational speed as used herein means the rotational speed of the spindle 22 per unit time (for example, per minute), and is synonymous with the rotational speed. Since the tool 32 is interlocked with the spindle 22, the rotation speed of the spindle 22 is equal to the rotation speed of the tool 32. Therefore, the rotation speed of the spindle 22 is synonymous with the rotation speed of the tool 32.

FIG. 4 is a diagram showing a cutting aspect of the work W when “k” is an integer. FIG. 4 shows aspects of the tool 32 and the work W when viewed from the axial direction of the spindle 22.

FIG. 4A shows a cutting mode of the work W in the case where “k” is 1. As shown in FIG. 4A, when “k” is 1, the tool 32 is between the blade 32A of the tool 32 and the workpiece W and the blade 32B of the tool 32 is in contact with the workpiece W. The wave number of the cutting surface caused by the vibration of is 1.

FIG. 4B shows a cutting mode of the work W when “k” is 2. The tool rotation speed in the cutting mode of FIG. 4(B) corresponds to 1/2 of the spindle rotation speed in the cutting mode of FIG. 4(A). As shown in FIG. 4B, when “k” is 2, the wave number on the cutting surface of the work W is 2.

FIG. 4C shows a cutting mode of the work W when “k” is 3. The spindle rotational speed in the cutting mode of FIG. 4(C) corresponds to 1/3 of the spindle rotational speed in the cutting mode of FIG. 4(A). As shown in FIG. 4C, when “k” is 3, the wave number on the cutting surface of the work W is 3.

In the cutting modes shown in FIGS. 4(A) to 4(C), since the deviation “φ” is 0, reproduction chatter vibration is unlikely to occur.

Whether the reproduction chatter vibration occurs or not depends on the relationship between the spindle rotation speed and the cut width of the work W. FIG. 5 is a diagram showing a stable range in which the reproduction chatter vibration does not occur and an unstable range in which the reproduction chatter vibration occurs in the relationship between the spindle rotation speed and the cutting width of the work W. In FIG. 5, the relationship between the stable range and the unstable range is shown as a stable lobe 60. The stable range is hatched, and the unstable range is not hatched.

The horizontal axis of the graph shown in FIG. 5 represents the spindle rotational speed. The vertical axis of the graph shown in FIG. 5 represents the cut width of the work. The "cutting width" referred to here is a width in which the tool 32 cuts the work W in the axial direction of the spindle 22 (hereinafter, also referred to as "cutting width Ap") and a direction orthogonal to the axial direction of the spindle 22, and is the work. This is a concept including a width in which the tool 32 cuts the work W in a direction orthogonal to the movement direction of the tool 32 with respect to W (hereinafter, also referred to as “cut width Ae”). That is, the vertical axis of the graph shown in FIG. 5 may be represented by the cut width Ap or the cut width Ae.

FIG. 6 is a diagram showing a manner of cutting the work W by the tool 32. FIG. 6 shows a tool 32 as an end mill. The tool 32 has a plurality of blades on its side surface, and cuts the work W by contacting the work W while rotating.

FIG. 6 shows a tool 32 as an end mill. The tool 32 has a plurality of blades on its side surface, and cuts the work W by contacting the work W while rotating along a predetermined path. As an example, the tool 32 sequentially cuts the first-stage cutting portion having the cutting width Ap for each cutting width Ae. Next, the tool 32 sequentially cuts the second cut portion of the cutting width Ap for each cutting width Ae. By repeating such cutting, the tool 32 cuts the work W into an arbitrary shape.

<C. Experiment>
In order to demonstrate that the stability range defined by the stability lobe 60 changes in accordance with the cutting direction of the work W by the tool 32, the inventors of the present invention have confirmed that the conditions causing regenerative chatter vibration change in each cutting direction. Confirmed by experiment. Below, the contents of an experiment conducted by the inventors will be described with reference to FIGS. 7 to 10.

FIG. 7 is a diagram showing the relationship between the work W and the cutting direction. The inventors examined the cutting conditions in which the reproduction chatter vibration occurs in the eight cutting directions d1 to d8 shown in FIG. The cutting direction here means a relative moving direction of the tool 32 with respect to the work W.

First, the inventors fixed the main shaft rotation speed to “n1” and examined the maximum cutting width Ae at which reproduction chatter vibration does not occur. Further, the initial feed rate of the spindle is set to "v1" and the cutting width Ap is set to "Ap1". Regarding the cutting width Ae, starting from “Ae1”, the cutting width Ae is sequentially increased in the order of “Ae2”→“Ae3”→“Ae4”→“Ae5” until reproduction chatter vibration occurs (that is, Ae1< Ae2<Ae3<Ae4<Ae5).

FIG. 8 is a diagram showing the results of examining the maximum cutting width Ae in which the reproduction chatter vibration does not occur for each cutting direction while fixing the spindle rotational speed.

As shown in FIG. 8, in the cutting direction d1, the reproduction chatter vibration occurs when the cutting width Ae is “Ae1” or more.

In the cutting directions d2, d4, d6 and d8, regenerative chatter vibration is not generated when the cutting width Ae is “Ae4” or less, and regenerative chatter vibration is generated when the cutting width Ae is “Ae5” or more.

In the cutting direction d3, the reproduction chatter vibration is not generated when the cutting width Ae is “Ae2” or less, and the reproduction chatter vibration is generated when the cutting width Ae is “Ae3” or more.

In the cutting direction d5, the reproduction chatter vibration is not generated when the cutting width Ae is “Ae1” or less, and the reproduction chatter vibration is generated when the cutting width Ae is “Ae2” or more.

In the cutting direction d7, the reproduction chatter vibration is not generated when the cutting width Ae is “Ae3” or less, and the reproduction chatter vibration is generated when the cutting width Ae is “Ae4” or more.

From the experimental results shown in FIG. 8, it can be seen that the maximum cutting width Ae at which regenerative chatter vibration does not occur differs depending on the cutting direction.

Next, the inventors examined the maximum cutting width Ae at which the reproduction chatter vibration does not occur after optimizing the spindle speed by using the MVC (Machine Vibration Control) function provided by DMG Mori Seiki. The MVC function is a function of suppressing the occurrence of reproduction chatter vibration by automatically controlling the spindle speed.

FIG. 9 is a diagram showing the results of examining the maximum cutting width Ae in which the reproduction chatter vibration does not occur for each cutting direction after optimizing the spindle speed.

As shown in FIG. 9, in the cutting direction d1, the spindle rotational speed is optimized to “n2” and the cutting width Ae is increased to “Ae4”.

In the cutting direction d3, the spindle speed is optimized to "n3", and the cutting width Ae is increased to "Ae4".

In the cutting direction d5, the spindle speed is optimized to "n4", and the cutting width Ae is increased to "Ae4".

In the cutting direction d7, the spindle speed is optimized to be "n5", and the cutting width Ae is increased to "Ae4".

In the cutting directions d2, d4, d6 and d8, the spindle speed did not change. That is, in the cutting directions d2, d4, d6 and d8, the spindle speed has already been set to the optimum value.

From the experimental results shown in FIG. 9, it can be seen that the spindle rotational speed for maximizing the cutting width Ae is different for each cutting direction.

FIG. 10 is a diagram showing stable lobes obtained from the above experimental results for each cutting direction. As shown in FIG. 10, the stability lobe is different for each cutting direction. It is presumed that such a difference in the stable lobe is caused by a difference in the internal structure of the machine tool, the rigidity of the work W depending on the direction, and the like.

From the above experimental results, the inventors have demonstrated that the cutting conditions that cause regenerative chatter vibration vary depending on the cutting direction.

In the above experiment, an example in which the cutting width Ap in the axial direction of the main shaft 22 is fixed and the cutting width Ae in the radial direction of the main shaft 22 is changed has been described, but the cutting width Ae is fixed and the cutting width Ae is fixed. The stability lobe changes for each cutting direction even when is changed. That is, the vertical axis of the stability lobe shown in FIG. 10 may be the cut width Ap of the main shaft 22 in the axial direction or the cut width Ae of the main shaft 22 in the radial direction.

<D. Reproduction chatter vibration suppression processing>
As described above, the cutting conditions in which the regenerative chatter vibration occurs vary depending on the cutting direction. Therefore, control device 101 (see FIG. 17) of machine tool 100 according to the present embodiment defines a stable range (a stable range) in which the reproduction chatter vibration does not occur in the relationship between the cutting width and the spindle speed. A stable lobe) is prepared in association with each cutting direction of the tool 32 with respect to the work W. Then, the control device 101 sets control parameters relating to at least one of the cutting width and the spindle rotational speed so that the cutting conditions of the cutting width and the spindle rotational speed fall within the stable range of the stable lobe corresponding to the current cutting direction. To do. As a result, the machine tool 100 can suppress the occurrence of regenerative chatter vibration regardless of the cutting direction.

The adjustment processing of the control parameter based on the cutting direction is realized by various methods. Hereinafter, a specific example of the control parameter adjustment process will be described with reference to FIGS. 11 to 13.

(D1. Concrete example 1 of control parameter adjustment processing)
First, a specific example 1 of the control parameter adjustment processing will be described with reference to FIG. 11. FIG. 11 is a diagram showing a cutting mode according to the first example. FIG. 11 shows a stable lobe 61 corresponding to the +X direction and a stable lobe 63 corresponding to the +Y direction.

In this specific example, the control device 101 of the machine tool 100 (see FIG. 17) has the cutting conditions of the spindle rotational speed and the cutting width in the overlapping range 70 of the stable range of the stable lobe 61 and the stable range of the stable lobe 63. The control parameter relating to at least one of the spindle rotational speed and the cutting width is adjusted so that it falls within the range. In the example of FIG. 11, the control condition indicated as the control parameter P0 is included in the overlapping range 70. As a result, the machine tool 100 can suppress the occurrence of reproduction chatter vibration regardless of whether the cutting direction is the +X direction or the +Y direction.

In one aspect, the machine tool 100 synthesizes the stable range of the stable lobe 61 and the stable range of the stable lobe 63 to generate a combined stable lobe representing the overlapping range 70, and the main spindle speed and the cut width correspond to the combined range. The control parameters are controlled so that they fall within the stable lobe. In another aspect, the machine tool 100 does not generate a combined stable lobe of the stable lobes 61 and 63, and the main spindle speed and the cutting width are within both the stable range of the stable lobe 61 and the stable range of the stable lobe 61. Control the control parameters so that they fit.

Preferably, the control device 101 of the machine tool 100 does not change the control parameter P0 according to the cutting direction of the tool 32 with respect to the work W. That is, the control device 101 does not change the spindle rotation speed and the cutting width even when the cutting direction changes. In the example of FIG. 11, the control parameter P0 is maintained even when the cutting direction changes from the +X direction to the +Y direction. As a result, the machine tool 100 can stabilize the cutting conditions, and as a result, can stabilize the cutting quality of the work.

In the example of FIG. 11, the example in which the control parameter is adjusted so that the cutting condition is contained in the overlapping range 70 of the two stable lobes 61 and 63 has been described. The control parameters may be adjusted to accommodate the cutting conditions. By considering more stable lobes in this way, it is possible to more reliably suppress the occurrence of reproduction chatter vibration.

(D2. Concrete Example 2 of Control Parameter Adjustment Processing)
Next, a specific example 2 of the control parameter adjustment processing will be described with reference to FIG. FIG. 12 is a diagram showing a cutting mode according to the second specific example. FIG. 12 shows a stable lobe 61 corresponding to the +X direction and a stable lobe 63 corresponding to the +Y direction.

In this specific example, the control device 101 (see FIG. 17) of the machine tool 100, each time the cutting direction is changed, selects from among the plurality of stability lobes corresponding to each cutting direction, the stability corresponding to the changed cutting direction. Select a robe. At this time, if there is no stability lobe that completely matches the current cutting direction, the stability lobe closest to the current cutting direction is selected. After that, the control device 101 sets at least one control parameter of the spindle rotational speed and the cutting width so that the spindle rotational speed and the cutting width fall within the stable range of the selected stable lobe. As described above, the machine tool 100 can improve the cutting efficiency while appropriately suppressing the reproduction chatter vibration regardless of the cutting direction by appropriately switching the stable lobes according to the current cutting direction.

In the example of FIG. 12, when the cutting direction is the +X direction, the control parameter PX is set so that it falls within the stable range of the stable lobe 61 corresponding to the +X direction. At this time, preferably, the control device 101 controls the control parameter so that the cutting width becomes maximum within the stable range of the selected stable lobe 61. More specifically, the control device 101 maximizes the cutting width within a predetermined range of the spindle rotational speed including the current spindle rotational speed and within the stable range of the stable lobe 61 corresponding to the +X direction. Set the control parameters to. As a result, the machine tool 100 can further improve the cutting efficiency while suppressing the occurrence of regenerative chatter vibration.

After that, it is assumed that the cutting direction is switched from the +X direction to the +Y direction. Based on this, the control device 101 selects the stable lobe 63 corresponding to the +Y direction from the previously prepared stable lobes 61, 63, and the main shaft rotation speed and the cutting width are stable. Switch the control parameters so that they are within the range.

In the example of FIG. 12, the control parameter PY is set. At this time, preferably, the control device 101 controls the control parameter so that the cutting width becomes maximum within the stable range of the selected stable lobe 63. More specifically, the control device 101 maximizes the cutting width within a predetermined range of the spindle rotational speed including the current spindle rotational speed and within the stable range of the stable lobe 63 corresponding to the +Y direction. Set the control parameters to. As a result, the machine tool 100 can further improve the cutting efficiency while suppressing the occurrence of regenerative chatter vibration.

In the example of FIG. 12, the control parameter is switched based on the two stable lobes 61 and 63, but the control parameter may be adjusted based on three or more stable lobes. This way more stable lobes are taken into account, which makes it less likely that playback chatter vibrations will occur.

(D3. Concrete Example 3 of Control Parameter Adjustment Processing)
Next, a specific example 3 of the control parameter adjustment processing will be described with reference to FIG. FIG. 13 is a diagram showing a cutting mode according to the third specific example. FIG. 13 shows a stable lobe 61 corresponding to the +X direction, a stable lobe 62 corresponding to the −X direction, a stable lobe 63 corresponding to the +Y direction, and a stable lobe 64 corresponding to the −Y direction. There is.

In this specific example, the control device 101 of the machine tool 100 (see FIG. 17) changes the cutting direction from the plurality of stable lobes corresponding to each cutting direction based on the change in the cutting direction. A corresponding predetermined number of stable lobes are selected, and control parameters are set so that they fall within the overlapping range of the selected predetermined number of stable ranges. The number of stable lobes selected may be constant regardless of the cutting direction, or may be different for each cutting direction. Further, the number of stable lobes to be selected may be defined in advance when the machine tool 100 is designed, or may be arbitrarily set by the user.

As an example, a stable lobe is selected that corresponds to a predetermined angular range (eg, ±90 degrees) about the current cutting direction. In the example of FIG. 13, when the cutting direction is the +X direction, a stable lobe 61 corresponding to the +X direction and a stable lobe 63 corresponding to the +Y direction are selected from the four stable lobes 61 to 64 prepared in advance. , And the stable lobe 64 corresponding to the −Y direction is selected. Then, the control device 101 switches the control parameter so that the main shaft rotation speed and the cutting width fall within the overlapping range 72A of the stable range of the stable lobes 61, 63, 64.

At this time, preferably, the control device 101 controls the control parameter so that the cutting width becomes maximum within the overlapping range 72A. More specifically, the control device 101 sets the control parameter so that the cutting width becomes maximum within a predetermined range of the spindle rotational speed including the current spindle rotational speed and within the overlapping range 72A. In the example of FIG. 13, the control parameter PX is set.

After that, it is assumed that the cutting direction of the tool 32 is switched from the +X direction to the +Y direction. Based on this, the control device 101 selects the stable lobe 62 corresponding to the −X direction, the stable lobe 63 corresponding to the +Y direction, and the −Y from among the four prepared stable lobes 61 to 64. The three stable lobes 64 corresponding to the direction are selected. Then, the control device 101 switches the control parameter so that the spindle rotation speed and the cutting width fall within the overlapping range 72B of the stable range of the stable lobes 62 to 64.

At this time, preferably, the control device 101 controls the control parameter so that the cutting width becomes maximum within the overlapping range 72B. More specifically, the control device 101 sets the control parameter so that the cutting width becomes maximum within a predetermined range of the spindle rotational speed including the current spindle rotational speed and within the overlapping range 72B. In the example of FIG. 13, the control parameter PY is set.

As a result, the machine tool 100 can further improve the cutting efficiency while suppressing the occurrence of regenerative chatter vibration.

<E. Control structure of machine tool 100>
The control structure of the machine tool 100 will be described with reference to FIGS. 14 to 16. The process executed by the machine tool 100 is divided into a process of generating a stable lobe corresponding to each cutting direction and a cutting process using the generated stable lobe.

FIG. 14 is a flowchart showing a process of generating a stable lobe corresponding to each cutting direction. 15 and 16 are flowcharts showing a cutting process using the generated stable lobe. More specifically, FIG. 15 shows the cutting process described in the above-mentioned “D1. Concrete example 1 of control parameter adjustment processing”. FIG. 16 shows the cutting process described in the above-mentioned “D2. Concrete example 2 of control parameter adjustment processing”.

The processing of FIGS. 14 to 16 is realized by the control device 101 (see FIG. 17) of the machine tool 100 executing a program. In other aspects, some or all of the processing may be performed by circuit elements or other hardware.

Further, the stable lobe generating step and the cutting step using the generated stable lobe may be performed by different machine tools 100 or the same machine tool 100. Further, the process of generating the stable lobe does not necessarily have to be performed by the machine tool 100, and may be performed by, for example, a server.

Hereinafter, the stable lobe generating step and the cutting step using the generated stable lobe will be described in order with reference to FIGS. 14 to 16.

(E1. Stable lobe generation process)
First, with reference to FIG. 14, a control flow of a stable lobe generation process corresponding to each cutting direction will be described.

In step S50, the control device 101 determines whether or not reproduction chatter vibration is occurring based on the output value of the acceleration sensor 110 (see FIG. 1). More specifically, the control device 101 samples the output signal of the acceleration sensor 110 at a predetermined sampling rate, and Fourier-transforms the sampling result for a predetermined time. As a result, a spectrum showing the vibration intensity for each frequency is calculated. After that, the control device 101 identifies the frequency component having the maximum vibration intensity from the calculated spectrum, and detects the reproduction chatter vibration when the vibration intensity of the frequency component exceeds a predetermined threshold.

When it is determined that reproduction chatter vibration is occurring (YES in step S50), control device 101 switches control to step S54. Otherwise (NO in step S50), the control device 101 switches control to step S52.

In step S52, the control device 101 changes the currently set control parameter. The control parameter to be changed is, for example, a control parameter group related to cutting such as the spindle speed, the cutting width, and the cutting direction. The method of changing the control parameter is arbitrary. As an example, a plurality of predetermined different control parameter groups are set in a predetermined order. Alternatively, the control parameters may be changed randomly.

In step S54, the control device 101 associates the current cutting condition (control parameter) in which the reproduction chatter vibration has occurred with the current cutting direction (angle) and stores it in the storage device 120. The cutting conditions stored in association with the cutting direction are, for example, the current spindle speed, the current vibration intensity, the current vibration frequency, the current spindle feed rate, the current cutting widths Ae, Ap, and the like.

In step S60, the control device 101 determines whether or not the cutting conditions stored in step S54 have been accumulated in a predetermined number or more for each cutting direction. The predetermined number is, for example, 2 or 3 or more. When the control device 101 determines that the predetermined number or more of the cutting conditions stored in step S54 are accumulated in each cutting direction (YES in step S60), the control device 101 switches the control to step S62. Otherwise (NO in step S60), control device 101 returns the control to step S52.

In step S62, the control device 101 generates a stable lobe corresponding to each cutting direction based on the cutting conditions for each cutting direction stored in step S54. Stable lobes are generated in various ways. As an example, the stability lobe is determined using the analytical method devised by Y. Altintas.

In the analysis method based on Y. Altintas, the equation of motion of the tool 32 is represented by a two-degree-of-freedom physical model in the X direction and the Y direction, as shown in the following equations (2) and (3).

(Equation 2)
_{x "+ 2G x ω x x} '+ ω x 2 x = F x / m x ··· (2)
(Equation 3)
y″+2G _y ω _y y′+ω _y ² y=F _y /m _y (3)
“Ω _x ”shown in the above equation represents the natural frequency [rad/sec] of the tool 32 in the X direction. “Ω _y ”represents the natural frequency [rad/sec] of the tool 32 in the Y direction. “G _x ”represents the damping ratio [%] in the X direction. “G _y ”represents the damping ratio [%] in the Y direction. " _Mx " represents the equivalent mass [kg] in the X direction. _{"M y"} represents the Y-direction of the equivalent mass [kg]. “F _x ”represents the cutting power [N] acting on the tool 32 in the X direction. “F _y ”represents the cutting power [N] acting on the tool 32 in the Y direction. "X"" and "y"" respectively represent the second derivative of time. "X'" and "y'" respectively represent the first derivative of time.

The formula (2), the cutting force _{"F x"} shown in (3), _{"F y"} is represented by the following formula (4) obtained in (5).

(Equation 4)
F _x =−K _t a _p h(φ)cos(φ)−K _r K _t a _p h(φ)sin(φ) (4)
(Equation 5)
F _y =+K _t a _p h(φ)sin(φ)-K _r K _t a _p h(φ)cos(φ)...(5)
“H(φ)” shown in the above equation represents the thickness [m ² ] at which the blade of the tool 32 cuts the work W. “A _p ”represents a cut width [mm] in the axial direction. “K _t ”represents the specific cutting resistance [N/m ² ] of the main component force. “K _r ”represents the ratio [%] of the main component force and the back component force.

Cutting power F _x, F _y, in order to vary the angle of rotation of the tool 32 "phi", cutting power F _x between the starting angle of the cutting as "phi _s" and end angle of the cutting "phi _e", F _y It is obtained by integrating and calculating the average of each. The rotation angle “φ _s ”and the rotation angle “φ _e ”are geometrically determined depending on the diameter D [mm] of the tool 32, the radial cutting width A _e [mm], the feeding direction, and the upper cut or the down cut. You can ask.

The eigenvalue Λ according to the above equations (2) and (3) is represented by the following equation (6), where ω _c is the frequency of the reproduction chatter vibration. However, each variable on the right side of the following equation (6) is obtained from the following equations (7) to (14).

(Equation 6)
Λ=−(a ₁ ±(a ₁ ² −4a ₀ ) ^½ )/2a ₀ (6)
(Equation 7)
a ₀ =Φ _xx (iω _c )Φ _yy (iω _c )(α _xx α _yy −α _xy α _yx )...(7)
(Equation 8)
a ₁ =α _xx Φ _xx (iω _c )+α _yy Φ _yy (iω _c )...(8)
(Equation 9)
Φ _xx (iω _c )=1/(m _x (−ω _c ² +2iG _x ω _c ω _x +ω _x ² )) (9)
(Equation 10)
_{Φ yy (iω c) = 1} / (m y (-ω c 2 + 2iG y ω c ω y + ω y 2)) ··· (10)
(Equation 11)
_{α xx = [(cos2φ e -2K} r φ e + K r sin2φ e) - (cos2φ s -2K r φ s + K r sin2φ s)] / 2 ··· (11)
(Equation 12)
_{α xy = [(- sin2φ e} -2φ e + K r cos2φ e) - (- sin2φ s -2φ s + K r cos2φ s)] / 2 ··· (12)
(Equation 13)
α _yx =[(-sin2φ _e +2φ _e +K _r cos2φ _e )-(-sin2φ _s +2φ _s +K _r cos2φ _s )]/2...(13)
(Equation 14)
_{α yy = [(- cos2φ e} -2K r φ e -K r sin2φ e) - (cos2φ s -2K r φ s -K r sin2φ s)] / 2 ··· (14)
Next, _assuming that the real part of the eigenvalue “Λ” is “Λ _R ”and the imaginary part is “Λ _I ”, the axial cut width a _{plim at} the stability limit and the main spindle rotation speed n _lim are respectively expressed by the following equations ( 15) and the equation (16).

(Equation 15)
a _prime =2πΛ _R (1+(Λ _I /Λ _R )2)/(NK _t )... (15)
(Equation 16)
n _lim =60ω _c /(N(2kπ+π−2 tan ⁻¹ (Λ _I /Λ _R ))) (16)
The machine tool 100 sequentially changes the values of “ω _c ”and “k” shown in the equations (15) and (16) while sequentially changing the limit cut width “a _limit ”and the spindle rotation speed “n _lim ”. A stable lobe is generated by calculation. Generation of such a stable lobe is performed for each cutting direction based on the cutting conditions stored in step S54, so that a stable lobe corresponding to each cutting direction is generated.

(E2. Cutting Step (Specific Example 1))
Next, with reference to FIG. 15, a specific example 1 of the cutting process based on the stable lobe for each cutting direction generated in the generating process shown in FIG. 14 will be described. 15 shows the cutting process described in the above-mentioned “D1. Concrete example 1 of control parameter adjustment processing”.

In step S110, the control device 101 of the machine tool 100 acquires a plurality of stable lobes corresponding to each cutting direction generated in the generation process shown in FIG. 14 described above.

In step S112, the control device 101 sets the control parameters relating to at least one of the spindle rotational speed and the cutting width so that the spindle rotational speed and the cutting width fall within the overlapping range of the stable lobes 61 of the stable lobes acquired in step S110. adjust. The control parameter adjustment processing in this step is as described with reference to FIG. 11, and therefore the description thereof will not be repeated.

In step S114, the control device 101 cuts the work based on the control parameters set in step S112.

In step S120, the control device 101 determines whether or not the cutting of the work has been completed. When the control device 101 determines that the cutting of the work is completed (YES in step S120), the process illustrated in FIG. 15 is completed. Otherwise (NO in step S120), control device 101 returns the control to step S114.

(E3. Cutting Step (Specific Example 2))
Next, with reference to FIG. 16, a specific example 2 of the cutting process based on the stable lobes generated in the generation process shown in FIG. 14 will be described. FIG. 16 shows the cutting process described in the above-mentioned “D2. Concrete example 2 of control parameter adjustment processing”.

In step S150, the control device 101 of the machine tool 100 cuts the work according to the set control parameters.

In step S152, the control device 101 determines whether or not the cutting of the work has been completed. When the control device 101 determines that the cutting of the work is completed (YES in step S152), the process illustrated in FIG. 16 is ended. Otherwise (NO in step S152), control device 101 switches control to step S160.

In step S160, the control device 101 determines whether the cutting direction has changed. As an example, the control device 101 identifies the current cutting direction by analyzing the cutting program 122 (see FIG. 17 ), and determines that the cutting direction has changed when the cutting direction is different from the previous cutting direction. (YES in step S160), control is switched to step S162. Otherwise (NO in step S160), control device 101 returns the control to step S150.

In step S162, the control device 101 acquires the stability lobe corresponding to the current cutting direction from among the plurality of stability lobes corresponding to each cutting direction generated in the generation process shown in FIG. At this time, if there is no stability lobe that completely matches the current cutting direction, the stability lobe closest to the current cutting direction is selected.

In step S164, the control device 101 adjusts control parameters relating to at least one of the spindle rotational speed and the cutting width such that the spindle rotational speed and the cutting width fall within the stable range of the stability lobe acquired in step S162. The control parameter adjustment processing in this step is as described with reference to FIG. 12, and thus the description thereof will not be repeated.

<F. Hardware configuration of machine tool 100>
An example of the hardware configuration of the machine tool 100 will be described with reference to FIG. FIG. 17 is a block diagram showing the main hardware configuration of machine tool 100.

The machine tool 100 includes a spindle 22, ball screws 25, 52, 54, a control device 101, a ROM 102, a RAM 103, a communication interface 104, a display interface 105, an input interface 109, an acceleration sensor 110, a servo. It includes drivers 111A to 111D, servomotors 112A to 112D (driving units), encoders 113A to 113D, and a storage device 120.

The control device 101 is, for example, an NC control device capable of executing an NC (Numerical Control) program. The NC controller is composed of at least one integrated circuit. The integrated circuit is configured by, for example, at least one CPU (Central Processing Unit), at least one ASIC (Application Specific Integrated Circuit), at least one FPGA (Field Programmable Gate Array), or a combination thereof.

The control device 101 controls the operation of the machine tool 100 by executing various programs such as the cutting program 122 (NC program) of the machine tool 100. The control device 101 reads the cutting program 122 from the storage device 120 to the ROM 102 based on receiving the execution command of the cutting program 122. The RAM 103 functions as a working memory and temporarily stores various data necessary for executing the cutting program 122.

A LAN, an antenna, etc. are connected to the communication interface 104. The machine tool 100 exchanges data with an external communication device via the communication interface 104. The external communication device includes, for example, a server and other communication terminals. The machine tool 100 may be configured to be able to download the cutting program 122 from the communication terminal.

The display interface 105 is connected to a display device such as the display 130, and sends an image signal for displaying an image to the display 130 according to a command from the control device 101 or the like. The display 130 is, for example, a liquid crystal display, an organic EL display, or another display device. As an example, the display 130 displays the stability lobes for each cutting direction in an overlapping manner, or displays the stability lobes corresponding to the current cutting direction.

The input interface 109 may be connected to the input device 131. The input device 131 is, for example, a mouse, a keyboard, a touch panel, or another input device capable of receiving a user operation.

The servo driver 111A sequentially receives the input of the target rotation speed (or target position) from the control device 101, and controls the servo motor 112A so that the servo motor 112A rotates at the target rotation speed. More specifically, the servo driver 111A calculates the actual rotation speed (or actual position) of the servo motor 112A from the feedback signal of the encoder 113A, and when the actual rotation speed is smaller than the target rotation speed, the servo motor 112A. Is increased, and when the actual rotation speed is higher than the target rotation speed, the rotation speed of the servo motor 112A is decreased. In this manner, the servo driver 111A brings the rotation speed of the servo motor 112A closer to the target rotation speed while sequentially receiving the feedback of the rotation speed of the servo motor 112A. The servo driver 111A moves a table 55 (see FIG. 1) connected to the ball screw 54 along the X-axis direction, and moves the table 55 to an arbitrary position in the X-axis direction.

By similar motor control, the servo driver 111B moves the guide 53 (see FIG. 1) connected to the ball screw 52 along the Y-axis direction, and moves the table 55 (see FIG. 1) on the guide 53 in the Y-axis direction. Move to any position. By performing similar motor control, the servo driver 111C moves the spindle head 21 (see FIG. 1) connected to the ball screw 25 to an arbitrary position in the Z-axis direction. By performing the same motor control, the servo driver 111D controls the rotation speed of the spindle 22.

The storage device 120 is, for example, a storage medium such as a hard disk or a flash memory. The storage device 120 stores the cutting program 122 according to the present embodiment, various control parameters 124 used in the cutting program 122 (for example, the spindle speed, the feed rate of the spindle 22, the cutting widths Ap, Ae, etc.) and the cutting directions. The stability lobe 126 and the like are stored. Each of the stability lobes 126 is defined by, for example, a predetermined arithmetic expression in which a limit cut width is used as an objective variable, and a current main spindle rotation speed and a vibration intensity of the reproduction chatter vibration are used as explanatory variables. Alternatively, the relationship between the limit cut width, the current spindle rotation speed, and the vibration intensity of the reproduction chatter vibration may be defined in a table format.

The storage location of the cutting program 122, the control parameter 124, and the stable lobe 126 for each cutting direction is not limited to the storage device 120, and the storage area (for example, cache area) of the control device 101, the ROM 102, the RAM 103, the external device. (For example, a server) or the like.

The cutting program 122 may be provided as a part of an arbitrary program instead of as a stand-alone program. In this case, the control process according to the present embodiment is realized in cooperation with an arbitrary program. Even a program that does not include some of such modules does not depart from the spirit of the cutting program 122 according to the present embodiment. Further, some or all of the functions provided by the cutting program 122 may be realized by dedicated hardware. Furthermore, the machine tool 100 may be configured in a form such as a so-called cloud service in which at least one server executes a part of the processing of the cutting program 122.

<G. Summary>
As described above, the machine tool 100 ensures that the spindle rotational speed and the workpiece cutting width fall within the stable range of the stable lobe corresponding to the current cutting direction based on the plurality of stable lobes corresponding to each cutting direction. First, the control parameter relating to at least one of the spindle speed and the cutting width is controlled. As a result, the machine tool 100 can suppress the occurrence of regenerative chatter vibration regardless of the cutting direction.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

21 spindle head, 22 spindle, 23, 43 housing, 25, 52, 54 ball screw, 30 automatic tool changer, 31 magazine, 32 tools, 32A, 32B blade, 33 extrusion mechanism, 34 tool holding part, 35 sprocket, 36 Arm, 50 moving mechanism, 51, 53 guide, 55 table, 60, 61, 62, 63, 64, 126 stability lobe, 70, 72A, 72B overlapping range, 100 machine tool, 101 control device, 102 ROM, 103 RAM, 104 communication interface, 105 display interface, 109 input interface, 110 acceleration sensor, 111A, 111B, 111C, 111D servo driver, 112A, 112D servo motor, 113A, 113D encoder, 120 storage device, 122 cutting program, 124 control parameter, 130 Display, 131 input device.

Claims (8)

A tool for cutting the work,
A spindle for rotating the work or the tool,
A drive unit for driving the spindle,
A stable range that defines a range of cutting conditions in which chatter vibration does not occur in the relationship between the cutting width of the work by the tool and the rotation speed of the spindle, in association with each cutting direction of the tool with respect to the work. And a storage device for storing , the cutting direction indicates a moving direction of the tool in a direction orthogonal to the axial direction of the spindle,
By controlling the driving direction of the spindle by the driving unit, a control device for controlling the cutting direction of the tool with respect to the workpiece, the control device, in the stable range corresponding to the current cutting direction. A machine tool that sets a control parameter relating to at least one of a cutting width of the work by the tool and a rotation speed of the spindle so that the cutting conditions are satisfied. The machine tool according to claim 1, wherein the control device sets the control parameter so that the cutting condition falls within an overlapping range of a plurality of stable ranges stored in the storage device. The machine tool according to claim 2, wherein the control device does not change the control parameter in accordance with a cutting direction of the tool with respect to the work. Each time the control device changes the cutting direction of the tool with respect to the workpiece, it selects a stable range corresponding to the changed cutting direction from a plurality of stable ranges stored in the storage device, The machine tool according to claim 1, wherein the control parameter is set to fall within a range. The machine tool according to claim 4, wherein the control device controls the control parameter so that the cutting width becomes maximum within the selected stable range. The control device, based on changing the cutting direction of the tool with respect to the workpiece, selects from a plurality of stable ranges stored in the storage device a predetermined number of stable ranges corresponding to the changed cutting direction. 2. The machine tool according to claim 1, wherein the control parameter is set so as to fall within the overlapping range of the selected predetermined number of stable ranges. A cutting method using a machine tool,
The machine tool is
A tool for cutting the work,
A spindle for rotating the work or the tool,
A drive unit for driving the main shaft,
The cutting method is
The step of obtaining a plurality of stable ranges that define a range of cutting conditions in which chatter vibration does not occur in the relationship between the cutting width of the workpiece by the tool and the rotational speed of the spindle is provided, and the plurality of stable ranges are , Respectively, each is associated with each cutting direction of the tool with respect to the work, the cutting direction indicates a moving direction of the tool in a direction orthogonal to the axial direction of the main shaft,
The cutting method further comprises
Controlling the driving direction of the spindle by the driving unit to control the cutting direction of the tool with respect to the work;
A control parameter relating to at least one of the cutting width of the workpiece by the tool and the rotational speed of the spindle is set so that the cutting condition falls within a stable range corresponding to the current cutting direction among the plurality of stable ranges. A cutting method, comprising: A cutting program executed on a machine tool,
The machine tool is
A tool for cutting the work,
A spindle for rotating the work or the tool,
A drive unit for driving the main shaft,
The cutting program, the machine tool,
The step of acquiring a plurality of stable ranges defining a range of cutting conditions in which chatter vibration does not occur in the relationship between the cutting width of the workpiece by the tool and the rotational speed of the spindle is executed, and the plurality of stable ranges are obtained. Are respectively associated with each cutting direction of the tool with respect to the work, the cutting direction indicates a moving direction of the tool in a direction orthogonal to the axial direction of the main spindle,
The cutting program, in addition to the machine tool,
Controlling the driving direction of the spindle by the driving unit to control the cutting direction of the tool with respect to the work;
A control parameter relating to at least one of the cutting width of the workpiece by the tool and the rotational speed of the spindle is set so that the cutting condition falls within a stable range corresponding to the current cutting direction among the plurality of stable ranges. A cutting program that executes the steps you perform.

Images