Machine tool vibration suppression system

Abstract

To provide a vibration suppression system, which can suppress chatter vibration at low cost and in a versatile manner by accurately calculating a stable rotation speed, without using a special vibration measurement instrument such as an acceleration meter.SOLUTION: A vibration suppression system 1 comprises: a sound collecting device 11 that measures processing sound generated during processing; an edge computer 12 that can receive data on processing sound from the sound collecting device 11, to which processing information including a processing condition and tool information can be inputted and which can output the data on processing sound and the processing information; and a server computer 13 and a computer 14 for FEM analysis that can transmit and receive data with respect to the edge computer 12. The computer 14 for FEM analysis identifies a resonant frequency of a tool on the basis of the processing information received from the edge computer 12. The server computer 13 identifies a frequency of chatter vibration on the basis of the resonant frequency identified by the computer 14 for FEM analysis, and calculates a stable rotation speed at which chatter vibration hardly occurs on the basis of the frequency of the chatter vibration and the processing information.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a vibration suppression system for suppressing vibrations that occur during machining in a machine tool that machines a workpiece by moving a tool and the workpiece relative to each other. [Background technology]

[0002] For example, in a machine tool in which a tool is supported on a rotatable spindle and the tool and workpiece are moved relative to each other while being fed to machine the workpiece, when the tool is used with a large protrusion, such as in boring, a decrease in tool rigidity can cause large machining vibrations (hereinafter referred to as chatter), leading to problems such as tool breakage and poor machined surface quality. Patent Document 1 discloses, as a conventional technique for suppressing chatter, an invention that suppresses chatter by measuring the resonance frequency of a mechanical system and selecting a rotational speed at which chatter is unlikely to occur (hereinafter referred to as a stable rotational speed). Patent Document 2 also discloses an invention that suppresses chatter by measuring the chatter frequency during machining and selecting a stable rotational speed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4177028 Publication [Patent Document 2] Patent No. 4703315 Summary of the Invention [Problem to be solved by the invention]

[0004] However, although the method of Patent Document 1 can calculate the stable rotation speed, it has the problem that it requires equipment and work to measure the machine's resonance frequency in advance, and the state when the machine is stopped is different from the state when it is processing, which causes errors in the calculation. The method of Patent Document 2 can calculate the stable rotation speed more accurately based on information on the machining state, but measuring the vibration acceleration using an accelerometer requires that the accelerometer and wiring be installed in an appropriate position inside the machine in advance.

[0005] Therefore, the present disclosure has been made in consideration of the above problems, and aims to provide a vibration suppression system for machine tools that can accurately calculate stable rotational speeds without using special vibration measuring equipment such as accelerometers, and that can suppress vibrations inexpensively and generally. [Means for solving the problem]

[0006] In order to achieve the above object, the present disclosure provides a vibration suppression system for suppressing vibrations occurring during machining in a machine tool that is equipped with a rotary shaft that rotates a tool or a workpiece and that performs machining of the workpiece by moving the tool and the workpiece relatively, the system comprising: A sound collection device that measures processing noise during processing; The processed sound data can be received from the sound collection device, and the processing conditions and , including the number of blades, tool diameter, and tool protrusion length of the tool used during machining Tool information and 、 an information acquisition device that can input processing information including the above and can output the processed sound data and the processing information; and a computing device capable of transmitting and receiving data to and from the information acquisition device. The arithmetic device includes a resonance frequency specifying unit that specifies a resonance frequency of the tool based on the machining information received from the information acquisition device, and a resonance frequency specifying unit that specifies a resonance frequency of the tool based on the machining information received from the information acquisition device. and the processed sound data received from the information acquisition device. a stable rotation speed calculation unit that specifies a chatter frequency based on the chatter frequency and the processing information, and calculates a stable rotation speed at which chatter is less likely to occur based on the chatter frequency and the processing information; a storage unit that stores the resonance frequency identified by the resonance frequency identification unit in association with the processing sound data, the processing information, and the stable rotation speed calculated by the stable rotation speed calculation unit; Equipped with 、 The stable rotation speed calculation unit selects, from the tool information stored in the storage unit, the tool information corresponding to the tool information transmitted from the information acquisition device, selects the resonance frequency stored in association with the selected tool information, identifies a chatter frequency within a certain frequency range including the selected resonance frequency, and calculates the stable rotation speed using the identified chatter frequency. It is characterized by: Another aspect of the present disclosure is characterized in that, in the above configuration, the machining conditions transmitted by the information acquisition device to the arithmetic device include a rotation speed of the rotary shaft during machining. Another aspect of the present disclosure is characterized in that, in the above configuration, the resonance frequency identifying unit identifies the resonance frequency from the tool information by a finite element method. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to accurately calculate the stable rotation speed even from machining sounds that contain noise measured with a sound collection device. Furthermore, since there is no need to install special vibration measurement equipment such as an accelerometer for each machine, measurements can be made using, for example, a commercially available computer or tablet. Therefore, compared to conventional methods, chatter can be suppressed more cheaply and versatility-wise, achieving stable machining. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing a block configuration of a vibration suppression system for a machine tool. [Figure 2] 4 is a flowchart relating to chatter suppression by the vibration suppression system. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. 1 is a block diagram showing an example of a vibration suppression system 1. The vibration suppression system 1 includes a sound collection device 11, an edge computer 12, a server computer 13, and an FEM analysis computer 14. The machine tool to be subjected to vibration suppression has a well-known configuration in which a tool held by a spindle (not shown) is rotated to machine a workpiece placed on a table below. The sound collector 11 is formed by a microphone provided on the machine tool and measures machining sounds generated during machining. The sound collector 11 also has an interface that can be connected to the edge computer 12. The edge computer 12, the server computer 13, and the FEM analysis computer 14 are provided separately from the machine tool. However, some or all of these computers may be provided in the NC device of the machine tool.

[0010] The edge computer 12 includes an information input unit 21 for inputting information and an information output unit 22 for outputting information. The edge computer 12 can be connected to a server computer 13 via a network, and can send and receive data to and from the server computer 13. The edge computer 12 is an example of an information acquisition device of the present disclosure. The server computer 13 includes a communication unit 31, an FFT calculation unit 32, a rotation speed calculation unit 33, and a storage unit 34. The communication unit 31 transmits and receives data to and from the edge computer 12 and the FEM analysis computer 14. The FFT calculation unit 32 performs FFT analysis of the machining noise based on the data from the FEM analysis computer 14. The rotation speed calculation unit 33 calculates the stable rotation speed from the result of the FFT calculation unit 32 and information sent from the edge computer 12. The storage unit 34 associates the information sent from the edge computer 12 and the FEM analysis computer 14 with the result information calculated by the FFT calculation unit 32 and the rotation speed calculation unit 33 and stores them.

[0011] The FEM analysis computer 14 can be connected to the server computer 13, and can send and receive data to and from the server computer 13, and performs FEM analysis using the well-known finite element method based on the information sent from the server computer 13. The server computer 13 and the FEM analysis computer 14 are examples of a calculation device of the present disclosure. The FEM analysis computer 14 is also an example of a resonance frequency identification unit of the present disclosure. The FFT calculation unit 32 and the rotation speed calculation unit 33 are also an example of a stable rotation speed calculation unit of the present disclosure.

[0012] Next, an example of a chatter suppression method using the vibration suppression system 1 will be described with reference to the flowchart of FIG. In step (hereinafter referred to as "S") 1, the sound collector 11 measures the machining sound of the target machine tool. In S2, the edge computer 12 connected to the sound collection device 11 stores the measured processed sound as data. In S3, the information input unit 21 inputs machining conditions and tool information into the edge computer 12. The machining conditions include the rotation speed of the spindle. The tool information includes some or all of the number of cutting edges, tool diameter, and tool projection length of the tool. In S4, the edge computer 12 transmits the machining conditions, tool information, and machining sound data to the server computer 13 via the communication unit 31. In S5, the server computer 13 transmits the tool information to the FEM analysis computer 14 via the communication unit 31.

[0013] In S6, the FEM analysis computer 14 calculates the resonance frequency based on the transmitted tool information and transmits the calculation result to the server computer 13. In S7, the FFT calculation unit 32 of the server computer 13 From the processed sound data sent from the edge computer 12, Only a certain frequency range including the transmitted resonance frequency is extracted and subjected to FFT to identify the chatter frequency. In S8, the rotational speed calculation unit 33 calculates a stable rotational speed using the known calculation method used in Patent Document 2 from the chatter frequency identified by the FFT calculation unit 32, the spindle rotational speed in the machining conditions sent from the edge computer 12, and the number of tool blades in the tool information. In S9, the storage unit 34 stores the machining conditions, tool information, machining sound data, chatter frequency, and stable rotation speed in association with each other. In S10, the server computer 13 transmits the stable rotation speed to the edge computer 12. In S11, the information output unit 22 displays the stable rotation speed on the edge computer 12. In S12, the operator or the edge computer 12 changes the rotation speed during machining to a stable rotation speed, thereby suppressing chatter.

[0014] As described above, the vibration suppression system 1 includes a sound collection device 11 that measures processing sounds during processing, an edge computer 12 that can receive processing sound data from the sound collection device 11, input processing information including processing conditions and tool information, and output processing sound data and processing information, and a server computer 13 and an FEM analysis computer 14 that can send and receive data to and from the edge computer 12. Then, the FEM analysis computer 14 identifies the resonance frequency of the tool based on the processing information received from the edge computer 12, and the server computer 13 identifies the chatter frequency based on the resonance frequency identified by the FEM analysis computer 14, and calculates a stable rotation speed at which chatter is less likely to occur based on the chatter frequency and the processing information. With this configuration, it is possible to accurately calculate the stable rotation speed even from machining sounds that contain noise measured by the sound collection device 11. Furthermore, since there is no need to install a special vibration measurement device such as an accelerometer for each machine, measurements can also be made using, for example, a commercially available computer or tablet. Therefore, it is possible to suppress chatter and achieve stable machining more cheaply and generally than before.

[0015] The configuration of the vibration suppression system of the present disclosure is not limited to the aspects described in the above embodiments, and can be modified as needed within the scope of the present disclosure. For example, in the above embodiment, the resonance frequency identifying unit estimates the resonance frequency of the tool through FEM analysis using an FEM analysis computer, but the resonance frequency may be identified from a database created based on the results of prior actual measurements.Furthermore, the resonance frequency may be identified by utilizing machine learning or the like from a database created by accumulating collected machining conditions, tool information, and machining sounds. Furthermore, in the above embodiment, the resonance frequency of the tool is estimated based on the tool information, but although the input work becomes more complicated, workpiece information may also be collected to estimate the resonance frequency of the workpiece. In addition, if it is desired to also target chatter caused by mechanical system resonance, even though it occurs less frequently than tool system chatter, information on the machine tool components, axis positions, etc. may also be obtained, and the resonant frequency of the mechanical system may be estimated in a similar manner.

[0016] In the above embodiment, a server computer and an FEM analysis computer are exemplified as the computing device, but a computing device including a resonance frequency identification unit and a stable rotation speed calculation unit may be configured as a single computer. In this case, the computing device may also include the function of an edge computer and serve as an information acquisition device. The vibration suppression system may further include a usage authorization system, so that the system can be used only after user registration and payment of a usage fee. [Explanation of symbols]

[0017] 1·· Vibration suppression system, 11·· Sound collection device, 12·· Edge computer, 13·· Server computer, 14·· FEM analysis computer, 21·· Information input unit, 22·· Information output unit, 31·· Communication unit, 32·· FFT calculation unit, 33·· Rotational speed calculation unit, 34·· Memory unit.

Claims

1. A vibration suppression system for suppressing vibrations occurring during machining in a machine tool that is equipped with a rotary shaft that rotates a tool or a workpiece and that performs machining of the workpiece by moving the tool and the workpiece relatively, comprising: A sound collection device that measures processing noise during processing; an information acquisition device that can receive processing sound data from the sound collection device, can input processing information including processing conditions and tool information including the number of blades, tool diameter, and tool protrusion length of the tool used during processing, and can output the processing sound data and the processing information; a computing device capable of transmitting and receiving data to and from the information acquisition device, the arithmetic device comprises: a resonance frequency identifying unit that identifies a resonance frequency of the tool based on the machining information received from the information acquisition device; a stable rotation speed calculation unit that identifies a chatter frequency based on the resonance frequency identified by the resonance frequency identifying unit and the machining sound data received from the information acquisition device, and calculates a stable rotation speed at which chatter is less likely to occur based on the chatter frequency and the machining information; and a storage unit that stores the resonance frequency identified by the resonance frequency identifying unit in association with the machining sound data, the machining information, and the stable rotation speed calculated by the stable rotation speed calculation unit, the stable rotational speed calculation unit selects, from the tool information stored in the memory unit, the tool information corresponding to the tool information transmitted from the information acquisition device, selects the resonance frequency stored in association with the selected tool information, identifies a chatter frequency within a certain frequency range including the selected resonance frequency, and calculates the stable rotational speed using the identified chatter frequency.

2. 2. The vibration suppression system for a machine tool according to claim 1, wherein the machining conditions transmitted by the information acquisition device to the arithmetic unit include a rotational speed of the rotary shaft during machining.

3. 3. The vibration suppression system for a machine tool according to claim 1, wherein the resonance frequency specifying unit specifies the resonance frequency from the tool information by a finite element method.

Images