TW201827159A - Device and method for cutting tool stiffness prediction in suppressing the cutting chatter comprise a spindle stiffness model, various types of knife bar database modules, a tool stiffness computation module, and a steady-state cutting condition calculation module - Google Patents

Abstract

The present invention provides a device and a method for cutting tool stiffness prediction in suppressing the cutting chatter, which is mainly to have built-in a cutting tool stiffness prediction unit in the computer of machining center. The cutting tool stiffness prediction unit comprises a spindle stiffness model, various types of knife bar database modules, a cutting tool stiffness computation module, and a steady-state cutting condition calculation module. This cutting tool stiffness prediction unit is stored inside the computer of the machine tool. When the chatter is determined to occur based on the cutting signal, the knife bar type is selected by a man-machine interface, and the cutting tool parameters and the cutting parameters are input. The steady-state cutting condition calculation module can analyze these dynamic parameters of the system by using the cutting chatter model, and further calculate the optimal spindle rotation speed and the optimal cutting depth of the machining center. Therefore the spindle rotation speed and the cutting depth of the machining center are corrected to avoid the chatter of the cutting tool.

Description

Device and method for cutting tool rigidity prediction to suppress cutting chatter

The present invention relates to a device and method for predicting cutting tool rigidity for suppressing cutting chatter, in particular to a tool rigidity data stored in a computer of a machine tool, which allows an operator to select a tool bar type and a tool on a human-machine interface. Parameters to obtain the optimal speed and cutting depth conditions; this is a processing optimization method for the control system to detect abnormal cutting signals and calculate the optimal cutting conditions according to the type of the arbor during the processing. .

When a traditional machine tool is used for cutting, the machining master will set the speed and cutting depth of the machining program according to the cutting conditions provided by the tool manufacturer. However, the machine characteristics of different machine manufacturers are different, and the same tools and cutting conditions are not the same. It must be completely applicable. When abnormal sounds or vibrations occur during the machining process, and the surface of the workpiece is not good, the abnormal situation is usually avoided by reducing the speed and depth of cut, but this will lead to a reduction in production efficiency and is not the best way to overcome the problem. method.

In recent years, due to the development of sensor technology and the maturity of computer operation and processing technology, the application technology of real-time processing to suppress cutting abnormalities has become more and more extensive. The technology used is the Fourier transform analysis of digital signals and the Altitas tremor Vibration theory. Referring to FIG. 1, a conventional method for cutting flutter suppression by a tool includes the following procedures: (a) when flutter occurs, execute (b) stop the machine, and exit the tool, and then use (c ) The impact hammer strikes the blade point, and (d) the acceleration gauge measures the blade point response, and then (e) the capture card captures the signal (the signal measured by the acceleration gauge), and the capture card passes the signal Go to the computer for (f) computer signal analysis and processing to obtain the tool rigidity; then, use the computer calculation software (g) to calculate the cutting steady state diagram, (h) the user selects the appropriate cutting conditions, and then (i) the machine continues to cut In order to achieve the goal of (j) chattering stop; however, the above-mentioned method needs to stop the machine tool and spend a lot of time and manpower to perform it, which is not enough to control the operating cost of the industry.

Therefore, in recent years, a sensor acceleration gauge is used to detect cutting vibration or a microphone is used to capture abnormal sound signals. The frequency of the cutting flutter is obtained after Fourier transform analysis of the signal, and then the fast formula S = fc * 60 / Z / N (S = Spindle speed, fc = chatter frequency, Z = number of tool edges, N = 1, 2, 3 ...) Calculate the optimal cutting speed, suppress abnormal vibration and continue cutting for more machine tool operators, this Although the method can quickly find the optimal speed, the information of the optimal depth of cut cannot be obtained, and the calculated optimal speed is an approximate value, so it is still likely to be unstable cutting conditions. . Therefore, how to accurately provide stable cutting condition information to operators is still a subject that the comprehensive processing machine industry needs to improve.

The main object of the present invention is to provide a device and method for predicting cutting tool rigidity for suppressing cutting chatter, through the spindle rigidity data of the machine tool, the tool rigidity model, and various types of tool holder database modules established in a computer, When machining abnormality is detected during the machining process, the spindle rigidity data is used in combination with the tool bar module and tool parameters to calculate the optimal cutting speed and depth of cut through the model to suppress the occurrence of machining abnormalities and improve the tool The service life and machine processing efficiency, compared with the previously known tool knock test, to find the best conditions to save time and manpower, and no problems such as experimental equipment consumables.

In order to achieve the above object, the device and method for suppressing cutting chatter of the tool rigidity prediction of the present invention, its preferred technical solution includes: detecting a vibration signal during processing by a sensing unit, and converting the frequency response diagram of the signal by Fourier transform. When the non-tool cutting frequency (vibration frequency) signal appears, the controller will stop the processing program and warn the user that the processing is abnormal. Please enter the processing tool bar and tool parameters, and the computer will The tool model combines the spindle rigidity data and internal computer calculations to output the optimal speed and cutting depth conditions for the user to choose. The user can arbitrarily choose this condition to avoid chatter vibration. At this time, the vibration signal captured at this time, cutting chatter The vibration frequency disappears, leaving only the stable cutting frequency of the tool.

The structural features and other functions and purposes of the present invention are described in detail with reference to the embodiments of the drawings as follows:

The device and method for suppressing cutting chatter of the present invention for cutting tool rigidity prediction is a technology for predicting cutting tool rigidity based on the theory of finite element method, which can predict the optimal cutting speed and cutting depth under the current processing state, and then make the comprehensive The processing machine can avoid cutting chatter and improve tool life and machining efficiency. Referring to FIG. 2, a preferred embodiment includes at least one sensing unit 1, an acquisition unit 2, and a computer 3 provided on the integrated processing machine 10 as hardware for implementing cutting flutter suppression technology of the present invention. Device, where:

The sensing unit 1 is preferably a vibration sensor (such as an accelerometer) for monitoring the vibration of the integrated processing machine 10. The vibration sensor is specifically installed at the vibration generating position of the integrated processing machine 10. For example, the spindle 101 or other selected positions are used to measure the vibration of the spindle 101 of the integrated processing machine 10, and the measured vibration signal can be fed back to the acquisition unit 2 described below for reading;

The capturing unit 2 is a signal capturing device of a sensor, which is connected to the vibration sensor of the sensing unit 1 and the computer 3 to capture the vibration obtained by the vibration sensor. Signal and converts the vibration signal into a computer-readable signal and transmits it to the computer 3; the acquisition unit 2 includes a single-chip processing and calculation for high-speed sampling, digital conversion and filtering of noise interference, To obtain correct vibration data; in addition, there is a storage device (such as an SD card) for real-time abnormal vibration storage, and the acquisition unit is connected to the aforementioned computer;

The computer 3 is an industrial computer set on the integrated processing machine 10. The computer 3 has a built-in tool rigidity prediction unit, and is connected to the acquisition unit 2 and the controller of the integrated processing machine 10 as a data integration bridge. Furthermore, the vibration signal calculation analysis and tool rigidity calculation of the integrated processing machine 10 are performed. The computer 3 can monitor the vibration generated by the integrated processing machine 10 through the vibration sensor and the acquisition unit 2 and use the computer 3 The computational analysis determines whether cutting flutter occurs, and the computer 3 feeds back the optimal cutting conditions of the controller of the integrated processing machine 10.

With the configuration of the above-mentioned devices such as the sensing unit 1, the capturing unit 2 and the computer 3, and the integrated processing machine 10, and referring to FIG. 3, the execution method of the tool rigidity prediction to suppress cutting chatter is: The measurement unit 1 (vibration sensor) monitors the vibration, obtains the vibration signal and rotation speed of the main shaft 101 of the integrated processing machine 10, and feeds it back to the acquisition unit 2, so that the acquisition unit 2 acquires the vibration signal and rotation speed, and The acquisition unit 2 is transmitted to the computer 3; the tool rigidity prediction unit in the computer 3 will use the vibration signal of the spindle 101 captured by the integrated processing machine 10 during the processing program operation to analyze the vibration information, and use the fast Fourier The change of the chattering frequency of the spindle 101 is found by conversion, so as to determine whether the chattering condition has been reached (judge whether chattering occurs); if the chattering condition is reached, the processing program is immediately stopped, waiting for the user Enter the cutting conditions of the integrated processing machine (including processing tool bar and tool parameters and cutting parameter input) on the operation panel of the integrated processing machine; the tool rigidity prediction unit of the computer 3 will be based on these parameters. The spindle rigidity data is used to calculate the rigidity of the tool, and finally the current optimal cutting parameters (speed and cutting depth) are obtained and output to the controller operation panel of the integrated processing machine 10 to provide users with choices and use these optimal conditions for processing So that the cutting efficiency of the comprehensive processing machine is effectively improved.

Referring to FIG. 4, the tool rigidity prediction unit 4 is built in the computer 3 described above, and includes a spindle rigidity model 41, various types of tool holder database modules 42, tool rigidity calculation modules 43, and steady-state cutting. Condition calculation module 44; wherein, the spindle rigidity model 41 includes rigidity data of the spindle 101 of the integrated processing machine 10, which is data corresponding to the frequency (Hz) and the rigidity (um / N); Group 42 contains simplified size data (length, outer diameter, inner diameter, taper, etc.) of various tool holders; the tool rigidity calculation module 43 is an arithmetic program combining material mechanics theory and finite element algorithms; the steady state The cutting condition calculation module 44 is a calculation program for quickly finding the optimal spindle speed and cutting depth based on the rigidity of the cutting point and the cutting conditions. After the user inputs the type of tool holder through the man-machine interface (control panel), the tool rigidity prediction unit 4 The corresponding tool bar data will be captured from various tool bar database modules 42. Then the user continues to input tool parameters (diameter, number of blades, tool length, elongation), cutting parameters, and the tool's rigidity prediction. single Element 4 will combine tool bar data and tool parameter and cutting parameter data, and perform finite element segmentation. The tool rigidity calculation module 43 will superimpose the model after the segmentation and the spindle rigidity module 41 to obtain the final result. The cutting edge of the tool is rigid, and then the optimal cutting conditions are calculated by the steady-state cutting condition calculation module 44.

Referring again to FIG. 4, the technical method for predicting cutting rigidity and cutting vibration of the tool rigidity prediction method of the present invention includes: when the integrated processing machine 10 is processing, the high-speed extraction of the spindle 101 by the extraction unit 2 described above. The vibration signal is transmitted to the computer 3 for analysis; the computer program of the computer 3 determines whether chattering occurs, and if the computer program judges that chattering occurs, the integrated processing machine 10 is automatically controlled to suspend processing; The man-machine interface of the controller displays the input screen of the tool bar type, tool parameters and cutting parameters to provide users with selection and input; after the input is completed, the controller will then transfer these data to the tool rigidity prediction of computer 3. Unit 4, the tool rigidity prediction unit 4 performs the above-mentioned operations based on these data, and further obtains the tool tip point rigidity, wherein the steady-state cutting condition calculation module 44 captures the tool tip point rigidity data and quickly calculates Optimal cutting conditions for five sets of spindle speed (cutting speed) and cutting depth, and output to the man-machine interface for users to choose a cutting arbitrarily Then the controller of the integrated processing machine 10 is modified to the optimal spindle speed and cutting depth according to the cutting conditions selected by the user, and processing is continued, while the computer 3 continues to acquire vibration signals and analyze and determine the computer program. Whether flutter occurs.

Referring again to FIG. 5, the cutting tool chatter vibration suppression method of the present invention is compared with the conventional cutting tool chatter vibration suppression method shown in FIG. 1. The conventional method for obtaining cutting tool rigidity steps (a) to (f), Stopping the machine and retreating the tool, respectively, and the use of instruments and equipment to perform percussion measurement operations, the machine has a long shutdown time, and the machine needs to go through the warm-up program to continue cutting. The method of the present invention is to suspend machine processing (b '), without exiting the tool, and directly selecting the tool bar type (c'), inputting tool parameters (d '), and inputting cutting parameters (e' on the man-machine interface board). ), The tool point rigidity can be obtained through the calculation of the tool rigidity prediction unit 4 shown in Figure 4. The process is fast, greatly reduces the cost of downtime, and has no equipment (acceleration gauge, impact hammer, signal line, etc.) consumption and damage. Maintenance issues. Moreover, in terms of finding the optimal cutting conditions, a conventional method is to manually find the optimal cutting point of the cutting steady-state diagram, and the steady-state cutting condition calculation module 44 described in the present invention can help the operator to quickly stabilize the cutting conditions. Find the stable cutting point on the state diagram, and output the optimal cutting conditions on the operation screen for the user to directly click. After selecting the cutting conditions, the machining action can be continued immediately, which is simpler and reduces the chance of human judgment and errors.

The effect achieved by the device and method for suppressing cutting chatter of the present invention for cutting tool rigidity prediction is to complete the prediction of cutting tool rigidity based on the theoretical basis of the finite element method in terms of cutting tool chattering. The tool rigidity is obtained by means of a theoretical model. This method can improve the conventional flutter suppression technology. The tool rigidity needs to be obtained through experimental methods of instruments and equipment. Stopping the machine will cause downtime costs and labor costs. Or it can measure the flutter frequency through a sensor to calculate the best using a simple formula. Rotation speed without the optimal cutting depth information and calculation results may have errors and other problems.

In summary, the device and method for suppressing cutting flutter of the tool rigidity prediction of the present invention are indeed practical and creative, and the application of its technical means is also novel and undoubted, and the efficacy and design purpose are indeed in line with each other. Said reasonable progress to the bright. To this end, an application for an invention patent was filed in accordance with the law, but I would like to ask Jun Bureau for detailed review and to grant the patent as a prayer.

10‧‧‧Integrated Processing Machine

101‧‧‧ Spindle

1‧‧‧sensing unit

2‧‧‧ Capture Unit

3‧‧‧ computer

4‧‧‧Tool rigidity prediction unit

41‧‧‧ Spindle Rigidity Model

42‧‧‧ various types of tool holder database module

43‧‧‧Tool rigidity calculation module

44‧‧‧ Steady cutting condition calculation module

FIG. 1 is a schematic diagram of the implementation steps of a conventional method for suppressing flutter. FIG. 2 is a schematic block diagram of the flutter suppression system of the present invention. FIG. 3 is a schematic diagram illustrating execution of each step of the chattering suppression method of the present invention. FIG. 4 is a schematic diagram of the judgment and execution procedure of each step of the chattering suppression method of the present invention. FIG. 5 is a schematic diagram of the implementation steps of the method for suppressing chattering according to the present invention.

Claims (6)

A device for predicting tool rigidity for suppressing cutting chatter, comprising: at least one sensing unit, an acquisition unit, and a computer provided on a comprehensive processing machine; the sensing unit is installed on a main shaft of the comprehensive processing machine , Measuring the vibration of the spindle, and feeding the measured vibration signal back to the capturing unit for reading; the capturing unit is connected to the sensing unit and the computer to capture the vibration signal obtained by the capturing unit The vibration signal is converted into a computer-readable signal and transmitted to the computer; the computer has a built-in tool rigidity prediction unit and is connected between the acquisition unit and the controller of the integrated processing machine, and the tool rigidity The prediction unit includes a spindle rigidity model, a tool bar database module of various types, a tool rigidity calculation module, and a steady-state cutting condition calculation module; the spindle rigidity model includes rigidity data of the spindle of the integrated processing machine; The various types of tool bar database modules include simplified size data of various tool bars; the tool rigidity calculation module captures the tool bar data of the various types of tool bar database modules, combined with input The tool parameters and cutting parameters are divided into finite elements, and the divided model is superimposed with the spindle rigid module to obtain the tool tip point rigidity. The steady-state cutting condition calculation module calculates the tool point point rigidity. To find the spindle speed and cutting depth. The tool rigidity prediction device for suppressing cutting chatter according to claim 1, wherein the sensing unit is a vibration sensor. As described in claim 1, the tool rigidity prediction device is used to suppress cutting chatter, wherein the acquisition unit includes a single chip for sampling, digital conversion, and filtering noise interference. The device for predicting cutting tool rigidity as described in claim 1, wherein the fetching unit includes a storage device for storing abnormal vibration in real time. A method for cutting tool rigidity prediction for suppressing cutting chatter, comprising: at least one sensing unit, an acquisition unit, and a computer provided on an integrated processing machine; when the integrated processing machine is processing, through the acquisition The fetching unit captures the vibration signal of the spindle and transmits it to the computer for analysis; the computer program determines whether chattering occurs. If the computer program determines that chattering occurs, it automatically controls the integrated processing machine to suspend processing; The man-machine interface of the controller of the integrated processing machine displays the input screen of the tool bar type, tool parameters and cutting parameters, and selects and enters the tool bar type, tool parameters and cutting parameters; after the input is completed, the controller will input the data It is transmitted to a built-in tool rigidity prediction unit of the computer. The tool rigidity prediction unit calculates the rigidity of the tool tip point by inputting the type of the arbor type, tool parameters and cutting parameters. The tool rigidity prediction unit is based on the tool tip. Point rigidity data, calculate the cutting conditions of multiple sets of spindle speed and cutting depth, and output to the person A user interface for reference a cutting conditions arbitrarily selected; and the integrated processing machine controller modifies the spindle speed and the cutting depth of the cutting conditions are selected, and continue processing. As described in claim 5, the method for predicting tool rigidity for suppressing cutting chatter, wherein the tool rigidity prediction unit includes a spindle rigidity model, a tool bar database module of various types, a tool rigidity calculation module, and a steady state. Cutting condition calculation module; the spindle rigidity model contains the rigidity data of the integrated processing machine's spindle; the various tool bar database modules include simplified size data of various tool rods; the tool rigidity calculation module captures the The tool bar data of various tool bar database modules, combined with the input tool parameters and cutting parameters, perform finite element segmentation operations, and superimpose the model after the segmentation with the spindle rigidity module to obtain the tool tip point rigidity. ; The steady-state cutting condition calculation module calculates with the rigidity of the tip point to find the spindle speed and cutting depth.