JP2022052634A - Chattering vibration suppressing method of machine tool - Google Patents

Abstract

To a chattering vibration suppressing method of a machine tool which suppresses chattering vibrations of the machine tool with a simple constitution without providing sensors for detecting the vibrations during working.SOLUTION: A method of suppressing chattering vibrations generated on a rotation shaft in a machine tool provided with the rotation shaft for rotating a tool includes a preceding process of previously measuring and storing a characteristic frequency of a machine at every machine coordinate, a first process of confirming the number of blades of the tool after working start, a second process of detecting a passage frequency of a cutting blade from the number of blades of the tool confirmed on the first process and the number of rotations of the rotation shaft, a third process of detecting a current value of the machine coordinate, and deciding agreement or disagreement of the number of natural vibrations of the machine stored on the preceding process on the position of the current value and the passage frequency of the cutting blade detected on the second process and a fourth process of being changed to an optimal number of rotations of the rotation shaft, when the characteristic frequency of the machine on the current value position agrees with the passage frequency of the cutting blade, on the third process.SELECTED DRAWING: Figure 4

Description

The present invention relates to a method for suppressing chatter vibration of a machine tool, and more particularly to a method for suppressing chatter vibration of a machine tool without providing sensors for detecting vibration during machining.

In a machine tool that rotates a tool or a workpiece to perform machining, the accuracy of the machined surface of the workpiece may deteriorate due to chatter vibration generated during machining. In order to suppress such chatter vibration, conventionally, an acceleration sensor, a microphone, or the like is attached to the machine tool to detect chatter vibration during machining, and the machining conditions are changed for machining (Patent Document). See 1 and 2).

For example, in the conventional example described in Patent Document 1, a tool capable of detecting chatter vibration of a machining center by an X-axis acceleration sensor and a Y-axis acceleration sensor, calculating the chatter vibration frequency based on the detected value, and reducing chatter vibration by this frequency. The number of rotations of the tool is calculated and the machining conditions (number of rotations of the tool) are changed. Further, in the conventional example described in Patent Document 2, when chatter vibration is detected by the vibration sensor while the machine tool is rotating the tool spindle, the amount of change is determined within the range between the upper limit value and the lower limit value. , The tool spindle is rotated at the second rotation speed in which the first rotation speed is changed by the above change amount.

Japanese Unexamined Patent Publication No. 2010-105160 Japanese Patent No. 6494891

However, in the above-mentioned conventional example, since it is necessary to mount the sensors for detecting chatter vibration during processing on the product and ship it, the cost of the product increases accordingly.

The present invention has been made for the above-mentioned circumstances, and an object of the present invention is that it is possible to suppress chatter vibration of a machine tool with a simple configuration without providing sensors for detecting vibration during machining. Technology is to be provided.

That is, in this invention, the sensors are not mounted on the product and shipped as in the conventional example, but the passing frequency (spindle) of the cutting edge is obtained by obtaining the natural frequency of the machine in advance by a hammering test or the like. When the value (calculated from the number of rotations and the number of blades) is close to the natural frequency of the machine, the number of spindle rotations is changed to avoid chatter vibration. It is preferable that the number of blades of the tool is described in the machining program.

In addition, the natural frequency of the machine changes depending on the axial position of the machine, so if the entire machine is managed with the natural frequency of one place, the conditions may drop even in areas where there is no problem, or conversely. It may be processed as it is without changing the conditions. Therefore, the natural frequency for each shaft position is also obtained in advance, and the controlled frequency is changed. As a result, it is not necessary to drop the place where the condition does not need to be dropped, and it is possible to reduce the extension of the processing time.

In order to achieve the above object, the chatter vibration suppressing method of the machine tool of the present invention is a method of suppressing chatter vibration generated in the rotary shaft in a machine machine provided with a rotary shaft for rotating a tool, in advance. The pre-process of measuring and storing the natural frequency of the machine for each machine coordinate, the first step of confirming the number of blades of the tool after the start of machining, and the number of blades of the tool confirmed in the first step. In the second step of detecting the passing frequency of the cutting edge from the number of rotations of the rotating shaft, and in the second step of detecting the current value of the machine coordinates and memorizing in the previous step at the position of the current value. Optimal rotation axis when the machine-specific frequency at the current value position and the passing frequency of the cutting edge match in the third step of determining the match or mismatch of the detected passing frequencies of the cutting edge and the third step. It is characterized by having a fourth step of changing to the number of rotations of.

According to the present invention, it is possible to suppress chatter vibration of a machine tool with a simple configuration without providing sensors for detecting vibration during machining.

It is a figure which shows the X-axis position of the machine tool to which this invention is applied, and shows the time when the X-axis is in the center. It is a figure which shows the X-axis position of the machine tool to which this invention is applied, and shows the time when the X-axis moves from the center in the X + direction. It is a figure which shows the X-axis position of the machine tool to which this invention is applied, and shows the time when the X-axis moves from the center in the X- direction. It is a flowchart which shows the chatter vibration suppression method of the machine tool of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing an X-axis position of a machine tool to which the present invention is applied, and shows a case where the X-axis is in the center.
In this embodiment, only the figure in which the X-axis is moved is shown, but the same applies to the other axes.
As shown in FIG. 1, the machine tool 100 to which the present invention is applied includes an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other, and a swivel C-axis around the Z-axis, and has an X-feed device 31, a Z-feed device. It is a machine tool having 32, a tool spindle 33, a tool 34, a work table 35, and a C rotating device 36, and machining a work W by the tool 34. The Y feed device is not shown. 2 and 3 are also views showing the X-axis position of the machine tool 100 to which the present invention is applied. FIG. 2 shows the case where the X-axis moves from the center to the X + direction, and FIG. 3 shows the X-axis at the center. Shows when moving from to X-direction.

As described above, in the chatter vibration suppression method of the present invention, the sensors are not mounted on the machine tool as a product and shipped as in the conventional example, but the natural frequency of the machine tool is determined in advance by a hammering test or the like. By finding, when the passing frequency of the cutting edge (calculated from the spindle rotation speed and the blade number) becomes a value close to the natural frequency of the machine tool, the spindle rotation speed is changed to avoid chatter vibration. It is a thing. Therefore, the machine tool 100 shown in FIG. 1 does not include sensors such as a vibration sensor and an acceleration sensor that detect chatter vibration itself during machining in the spindle device (Z feed device 32). That is, before shipping the machine tool 100 as a product, for example, as shown in FIG. 1, the natural frequency of the machine tool 100 is obtained in advance by a hammering test or the like with the X axis in the center.

Further, since the natural frequency of the machine changes depending on the axial position of the machine, the entire machine tool 100 is managed by the natural frequency of a certain place (for example, the state where the X axis shown in FIG. 1 is in the center). If there is, the condition will be dropped even in the area where there is no problem, or conversely, the condition will not change and it will be processed as it is. Therefore, the natural frequency for each different shaft position is also obtained in advance by the above-mentioned hammering test or the like, and the controlled frequency is changed. As a result, it is not necessary to drop the place where the condition does not need to be dropped, and it is possible to reduce the extension of the processing time. That is, for example, as shown in FIG. 2, the natural frequency when the X-axis position of the machine tool 100 is moved from the center in the X + direction, and further, as shown in FIG. 3, the X-axis position of the machine tool 100 is. The natural frequency when moving from the center to the X- direction is also obtained in advance by the above-mentioned hammering test or the like.

FIG. 4 is a flowchart showing a chatter vibration suppressing method of the machine tool of the present invention. In the method for suppressing chatter vibration of a machine tool of the present invention, as described above, sensors are not mounted on a product (for example, the machine tool 100 shown in FIGS. 1 to 3) and shipped, but a hammering test or the like is performed. (For example, when the X-axis position in FIG. 1 is in the center, when the X-axis position in FIG. 2 moves from the center to the X + direction, the X-axis position in FIG. 3 is from the center. Find the natural frequency (when moving in the X- direction). Then, as shown in FIG. 4, when the machining is started (S401), first, the number of blades of the tool is confirmed (S402). Subsequently, the passing frequency of the cutting edge is detected from the number of blades of the tool and the number of rotations of the spindle confirmed (S403). Further, the machine coordinates are detected (S404), and the current value position (for example, when the X-axis position in FIG. 1 is in the center, when the X-axis position in FIG. 2 moves from the center in the X + direction, the X-axis in FIG. 3 Does the machine natural frequency at (when the position moves from the center to the X- direction) and the passing frequency of the cutting edge do not match? Judgment (S405). Here, if they do not match (Yes in S405), the spindle speed remains the same (S406), and is the programmed machining (target) completed? If it is determined (S407) and if it is completed (Yes in S407), the machining by the machine is terminated (S408). On the other hand, if the programmed machining (target) is not completed (No in S407), the processing from S404 is repeated. In S405, if the machine natural frequency at the current value position and the passing frequency of the cutting edge match (No in S405), the spindle speed is changed to the optimum one (S409). And whether or not the programmed machining (target) is completed? If it is determined (S407) and if it is completed (Yes in S407), the machining by the machine is terminated (S408). On the other hand, if the programmed machining (target) is not completed (No in S407), the processing from S404 is repeated.

In the embodiment described above, in order to simplify the explanation, the case where the X-axis position of the machine tool 100 moves is described by taking the case where the X-axis positions are located at the three locations of FIGS. 1, 2, and 3 as an example. However, it is not limited to the case where the X-axis positions are located at these three locations, and it is of course possible to obtain and manage the natural frequency for each finer machine coordinate. Further, although only the X-axis position has been described as an example, the present invention describes the natural frequency and the cutting edge for each machine coordinate when the machine drive axis of the machine machine such as the X-axis, the Y-axis, and the Z-axis moves. It is also applied when changing to the optimum rotation speed of the rotation axis when the passing frequencies of are the same.

31 X feed device, 32 Z feed device, 33 tool spindle, 34 tool,
35 work table, 36 C rotating device, 100 machine tool, W work

Claims (1)

A method of suppressing chatter vibration generated in the rotating shaft in a machine tool provided with a rotating shaft for rotating a tool.
Before the process of measuring and storing the natural frequency of the machine for each machine coordinate in advance,
After the start of machining, the first step of confirming the number of blades of the tool and
The second step of detecting the passing frequency of the cutting edge from the number of blades of the tool confirmed in the first step and the number of rotations of the rotating shaft, and
The third step of detecting the current value of the machine coordinates and determining the match or mismatch between the natural frequency of the machine stored in the previous step at the position of the current value and the passing frequency of the cutting edge detected in the second step.
The third step is a work characterized by having a fourth step of changing the rotation frequency of the rotation axis to the optimum rotation frequency when the natural frequency of the machine at the current value position and the passing frequency of the cutting edge match. Machine tool chatter vibration suppression method.

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