JP2006150504A - Machining device capable of predicting/preventing chattering oscillation and method for predicting/preventing chattering oscillation used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a machining device capable of predicting/preventing chattering oscillation, and a method of predicting/preventing chattering oscillation used for the same. <P>SOLUTION: Not only the chattering oscillation in a current process can be prevented, but also the occurrence of the chattering oscillation in the next process can be predicted on the basis of oscillation data of a workpiece and machining conditions in the current process. The chattering oscillation in the next process is prevented by correcting machining conditions for the next process. By this, efficient cutting can be executed without reducing a machining speed by preventing the chattering oscillation individually for each process to a plurality of the processing processes. The chattering oscillation in the next process can be prevented by successively using oscillation data of the workpiece in a plurality of the processes for the correction of the machining conditions for the next process or the process after the next process. Consequently, prevention of the chattering oscillation over the entire machining of the workpiece can be realized. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a chatter vibration prediction preventing processing apparatus having a chatter vibration prediction preventing function and a chatter vibration prediction preventing method of the chatter vibration prediction preventing processing apparatus.

  In cutting, which is the basic cutting mode of end milling, chatter vibration is one of the factors that hinders the increase in cutting speed. For this reason, this chatter vibration has been suppressed during workpiece machining.

  FIG. 1 shows a conventional workpiece machining apparatus. A work processing apparatus 10 shown in FIG. 1 includes a workbench 20, a processing head 30, and a controller 40 that controls operations of the workbench 20 and the processing head 30.

The workbench 20 can turn the table 4 on the base 2 around the vertical axis Pv, that is, in a horizontal plane. On the table 4, an upwardly extending block 5 is integrally provided at a position offset from the rotation axis. The block 5 is provided with a work holding part 7 for holding the work W so as to face the center part side of the hand boules 4. The work holding unit 7 can be rotated around the horizontal axis, that is, in the vertical plane, by the rotation mechanism 6 provided in the block 5. The machining head 30 is provided with a machining tool 8 so as to face the workpiece W held by the workpiece holding unit 7, and this machining tool holding unit 8 is, for example, X, Y, Z, etc. It is possible to move in the three axis directions. The processing tool holding unit 8 is a so-called spindle, and can rotate the held processing tool T about its axis.

Thereby, in the workpiece machining apparatus 10, the machining tool holding unit 8 can move in the three axis directions of X, Y, and Z, and the workpiece holding unit 7 can rotate in the A direction and the B direction. A total of five axes of motion can be performed between the processing tool T held by the tool holder 8 and the workpiece W held by the workpiece holder 7.

Further, as shown in FIG. 2, the workpiece machining apparatus 10 includes a vibration detection sensor 50 including an accelerometer or a strain sensor in order to detect chatter vibration generated in the workpiece W and the machining tool T during machining.

The vibration detection sensor 50 is held by the workpiece holding unit 7 that holds the workpiece W. The detection signal output from the vibration detection sensor 50 is amplified by the amplifier 51 and then input to the FFT analyzer 52. The FFT analyzer 52 performs monitoring by frequency analysis of the detection signal output from the vibration detection sensor 50. The vibration detection sensor 50, the amplifier 51, and the FFT analyzer 52 constitute a vibration detection unit.

When the controller 40 receives, from the FFT analyzer 52, data indicating that chatter vibration having an amplitude greater than or equal to the specified intensity has been detected at a frequency other than the natural frequency of the machining tool T, processing for correcting the machining conditions by the machining tool T is performed. Execute.

FIG. 3 shows a processing flow in the controller 40. In the controller 40, when machining of the workpiece is started in the workpiece machining apparatus 10, the machining tool T is moved in the X, Y, Z and A, B directions of the workpiece holding unit 7 based on the NC program inputted in advance. Work W is processed according to the movement. After the start of machining, the controller 40 checks whether or not a signal for detecting chatter vibration on the machining tool T or the workpiece W is received from the FFT analyzer 52 (step S101). If the signal that has detected chatter vibration has not been received, it is checked in the NC program whether the machining has been completed up to the final step in the process (step S102), and the process of step S101 is repeated until the process is completed.

If a signal causing chatter vibration is received in step S101, first, the rotational speed of the machining tool T is increased by a predetermined amount set in advance (step S103). And it is checked again whether the signal which detected the chatter vibration on the processing tool T or the workpiece | work W is received from the FFT analyzer 52 (step S104). As a result, when the signal which detected chatter vibration is not received, it returns to step S101 and repeats a process. On the other hand, when a chatter signal is detected, that is, when chatter vibration is not suppressed by the machining tool T or the workpiece W, the amount of cutting per workpiece by the machining tool T is set in advance. The amount is decreased by a certain amount (step S105). In this case, processing for adding (extending) a machining process is performed in the NC program in order to compensate for the machining speed delay caused by the reduced cutting amount (step S106).

In the conventional workpiece processing apparatus 10 described above, it is efficient for a plurality of processes (rough machining, intermediate machining, finishing machining, etc.) without individually reducing chatter vibration for each process and reducing the machining speed. Cutting can be performed. However, in a number of processes, the detection results of chatter vibration in each process and the machining condition correction data for prevention are correlated with the data of these machining conditions despite the influence of the machining conditions of the previous process. Chatter vibration has been prevented without using it for the first time. For this reason, it is impossible to predict chatter vibration in the next process, and chatter vibration cannot be completely prevented even during finishing which is most important in workpiece machining.

Further, when processing a workpiece, a processing time is required to prevent chatter vibration in proportion to the number of steps.

  The following reports have been made on the above-described technology.

  In the “control method of cutting specifications” disclosed in Japanese Patent Application Laid-Open No. 7-171737, variation factors such as cutting specifications are calculated separately, and selection of a cutting tool and setting of cutting specifications are appropriate. There are various cutting tools, attachments, machine tools, etc. included in the calculation, and data is accumulated by coefficientizing each factor to control the cutting parameters to obtain the optimum cutting parameters. Proposed.

  The Journal of Precision Engineering VOL. 62, no. 8, 1996, "Research on regenerative chatter vibration in end milling (1st report)", in order to advance high-speed and high-efficiency machining, the chatter vibration generation limit is clarified and practical. It is important to find a critical limit diagram. For this reason, the stability of regenerative chatter vibration is theoretically analyzed in consideration of the dynamic cutting force that has been confirmed to be important in turning operations, that is, the cutting force proportional to the vibration velocity in the cutting direction of the tool, The effects of various cutting parameters on the vibration generation limit were discussed. In addition, numerical calculations were performed for side cutting, which is the basic cutting mode of end milling.

  The Journal of Precision Engineering VOL. 63, no. 3, "Research on regenerative chatter vibration in end milling (2nd report)" reported in 1997, an experimental analysis was conducted on the theoretical analysis of the limit of regenerative chatter vibration in end milling. It was conducted. Experimental analysis was also conducted on various cutting conditions, end mill vibration characteristics, and vibration generation regions on the cutting surface that affect the vibration generation limit. For this purpose, cutting experiments were performed in which cutting conditions such as cutting speed, cutting width, and cutting depth, end mill vibration characteristics and cutting edge helix angle were changed. As a result, the influence on the vibration generation limit was investigated in detail.

JP-A-7-171737 Hisataka Tanaka, Fumio Komine, Masami Ashimori, Juzo Matsubara “Research on Regenerative Chatter Vibration in End Mill Processing (1st Report)”, Journal of Japan Society for Precision Engineering VOL. 62, no. 8, 1996 Hisaka Tanaka, Fumio Kosuge, Masami Ashimori, Juzo Matsubara, Jun Ueki, Eisuke Moriwaki “Study on Regenerative Chatter Vibration in End Mill Processing (2nd Report)”, Journal of Precision Engineering VOL. 63, no. 3, 1997

  An object of the present invention is to provide a chatter vibration prediction preventing processing apparatus and a chatter vibration prediction preventing method of the chatter vibration prediction preventing processing apparatus.

  In the following, means for solving the problem will be described using reference numerals with parentheses used in [Best Mode for Carrying Out the Invention]. These symbols are added in order to clarify the correspondence between the description of [Claims] and the description of the best mode for carrying out the invention. ] Should not be used for interpretation of the technical scope of the invention described in the above.

  The chatter vibration prediction prevention method of the present invention includes a step of acquiring workpiece vibration data in the current process, a step of preventing workpiece chatter vibration in the current process based on the workpiece vibration data acquired in the acquiring step, and Furthermore, using the workpiece vibration data acquired in the step of acquiring, the step of predicting the occurrence of chatter vibration in the next process with higher finishing accuracy and the result of occurrence of chatter vibration predicted in the step of predicting And a step of correcting machining data for machining a workpiece in the next process.

  The predicting step of the chatter vibration prediction preventing method of the present invention includes a first calculation step of calculating a cutting force for the workpiece in the current process from machining data for machining the workpiece in the current process and a specific cutting resistance of the workpiece, Based on the cutting force and vibration data calculated in one calculation step, the second calculation step for calculating the dynamic rigidity of the workpiece in the current process, the dynamic rigidity calculated in the second calculation step and the CAD data of the workpiece in the next process The third calculation step for calculating the dynamic rigidity K of the workpiece in the next process, the value of the dynamic rigidity K of the workpiece in the next process calculated in the third calculation step and the machining data for processing the workpiece in the next process are collated. And predicting the occurrence of chatter vibration in the next process.

  In addition, the chatter vibration prediction preventing method of the present invention is performed at a plurality of machining positions of a workpiece.

  Further, the workpiece machining method of the present invention processes the workpiece held in the step of holding the workpiece by the workpiece holder and (A) the step of holding the workpiece by a machining tool for machining the workpiece based on the machining data. And (B) a step of acquiring vibration data of the workpiece while the vibration detection unit installed in the workpiece holding unit is being processed in the step of processing the workpiece in the current process, and (C) acquiring A step of preventing chatter vibration of the workpiece in the current process based on the workpiece vibration data acquired in the step; and (D) a higher finishing accuracy by using the workpiece vibration data acquired in the acquisition step. A step of predicting the occurrence of chatter vibration in the next process, and (E) chatter vibration predicted in the prediction step. Based on the occurrence or non-occurrence results and a step of repeatedly performing the steps from the step of modifying the machining data for machining a workpiece in the subsequent step (A) to (E) to a final finish precision process.

  The step of predicting the workpiece machining method of the present invention includes a first calculation step of calculating a cutting force on the workpiece in the current process from machining data for machining the workpiece in the current process and a specific cutting resistance of the workpiece, Based on the cutting force and vibration data calculated in the calculation step, the second calculation step for calculating the dynamic stiffness of the workpiece in the current process, the dynamic stiffness calculated in the second calculation step, and the CAD data of the workpiece in the next process The third calculation step for calculating the dynamic rigidity K of the workpiece in the next process, the value of the dynamic rigidity K of the workpiece in the next process calculated in the third calculation step and the machining data for processing the workpiece in the next process are collated. Predicting the occurrence of chatter vibration in the next process.

  The workpiece machining method of the present invention is performed at a plurality of machining positions of the workpiece.

  Moreover, the chatter vibration prediction preventing machining apparatus of the present invention includes a workpiece holding unit (70) that holds a workpiece (W) and a machining tool holding that holds a machining tool for machining the workpiece based on machining data of the current process. A vibration detection unit (500, 510, 520) that is installed in the unit (80), is installed in the work holding unit, and acquires vibration data of the current process of the work while the work is being processed by the processing tool; Prevents chatter vibration of the workpiece in the current process based on the workpiece vibration data acquired in, and also uses the vibration data of the workpiece in the current process acquired by the vibration detector to improve chatter in the next process with higher finishing accuracy. A controller (400) that predicts whether or not vibrations are generated, and corrects machining data of the next process for machining a workpiece in the next process based on the prediction result.

  The controller (400) related to the chatter vibration prediction preventing processing device of the present invention includes a CPU (420) and a memory (410), and the memory includes a program for processing the workpiece (W) and a plurality of steps. The CPU has machining data corresponding to each of the above, and the CPU calculates from the machining data of the workpiece in the current process and the specific cutting resistance of the workpiece based on the program, the cutting force on the workpiece in the current process, vibration data and the cutting force. Based on the dynamic stiffness of the workpiece in the current process, and the dynamic stiffness of the workpiece in the next process based on the dynamic stiffness and the CAD data of the workpiece in the next process, the value of the dynamic stiffness K of the workpiece in the next process and the value of the next process Predict the presence or absence of chatter vibration in the next process by collating with the machining data for machining the workpiece. To modify the processing data to do this.

  Further, the chatter vibration prediction preventing processing device of the present invention corrects the processing data of the next process for processing the workpiece for each of the plurality of processing positions of the workpiece.

  Moreover, the machining center of this invention is provided with the chatter vibration prediction prevention processing apparatus as described in any one of Claim 9-12.

  Further, the chatter vibration prediction preventing program of the present invention includes a workpiece holding unit (70) that holds a workpiece (W) and a machining tool (T) that holds a machining tool (T) for machining a workpiece based on machining data of the current process. A tool holding unit (80), a vibration detection unit (500, 510, 520) that is installed in the workpiece holding unit and acquires vibration data of the current process of the workpiece while the workpiece is being machined by the machining tool; Prevents chatter vibration of the workpiece in the current process based on the workpiece vibration data acquired by the detection unit, and further uses the vibration data of the current process of the workpiece acquired by the vibration detection unit for the next process with higher finishing accuracy. A controller (400) that predicts the occurrence of chatter vibration in the machine and corrects the machining data of the next process for machining the workpiece in the next process based on the prediction result. A chatter vibration prediction preventing program provided in the chatter vibration prediction preventing processing apparatus, wherein the controller includes a CPU (420) and a memory (410), and the memory corresponds to the vibration prediction preventing program and each of the plurality of steps. When turning on the chatter vibration prediction prevention processing device that has machining data, the CPU reads the vibration prediction prevention program from the memory and cuts the workpiece in the current process from the machining data corresponding to the current process and the specific cutting resistance of the workpiece. Calculates the dynamic stiffness of the workpiece in the current process from the force, vibration data and cutting force, and the dynamic stiffness K of the workpiece in the next process based on the dynamic stiffness and CAD data of the workpiece in the next process. The value of the dynamic rigidity K of the workpiece in the process is compared with the machining data for machining the workpiece in the next process. Ri predict the occurrence or non-occurrence of the vibration to modify the processing data of the next step of processing the workpiece at the next step on the basis of the prediction result.

  Further, the chatter vibration prediction preventing program of the present invention corrects machining data of the next process for machining a workpiece at a plurality of machining positions of the workpiece.

  According to the present invention, it is possible to provide a chatter vibration prediction preventing processing apparatus having a chatter vibration prediction preventing function and a chatter vibration prediction preventing method of the chatter vibration prediction preventing processing apparatus.

This makes it possible to predict and prevent chatter vibration of the entire cutting process, and to completely prevent chatter vibration during finishing, which is the most important quality of the machined surface. In addition, the processing time can be shortened and productivity can be improved.

  Referring to the accompanying drawings, the best mode for carrying out the chatter vibration prediction preventing processing apparatus having the chatter vibration prediction preventing function according to the present invention and the chatter vibration prediction preventing method of the chatter vibration prediction preventing processing apparatus will be described below. explain.

The chatter vibration prediction preventing processing apparatus according to the present invention is an apparatus for cutting a workpiece that is a cutting target through a plurality of steps. The chatter vibration prediction preventing processing apparatus according to the present invention not only prevents chatter vibration in the current process, but also predicts occurrence of chatter vibration in the next process based on vibration data during machining of the workpiece in the current process. And chatter vibration in the next process is prevented by correcting the processing conditions of the next process in advance. As a result, in the chatter vibration prediction preventing processing apparatus according to the present invention, for a plurality of processes (rough machining, intermediate machining, finishing machining, etc.), chatter vibration is individually prevented for each process to reduce the machining speed. Efficient cutting can be performed without any problems. Furthermore, the vibration data of a workpiece in a plurality of processes is sequentially used for correcting the machining conditions of the next process to prevent chatter vibration in the next process, thereby preventing chatter vibration throughout the entire machining of the workpiece. In addition, the machining time of the workpiece can be shortened, and the production efficiency can be improved. In addition, since the chatter vibration is prevented throughout the workpiece machining, the quality of the workpiece machining surface during finishing can be improved.

(Embodiment of the present invention)
The basic configuration of the chatter vibration prediction preventing processing apparatus according to the embodiment of the present invention is the same as that of the conventional workpiece processing apparatus 10 shown in FIG. However, in the chatter vibration prediction preventing machining device of the present embodiment, the control unit that detects vibration and corrects the machining condition of the workpiece in the next process using the vibration data has a difference from the conventional workpiece machining device 10. is there.

FIG. 4 shows a vibration detection unit and a control unit of the chatter vibration prediction preventing processing apparatus according to the embodiment of the present invention. The vibration detection unit of the chatter vibration prediction preventing processing apparatus according to the present embodiment includes a vibration detection sensor 500 including an accelerometer or a strain sensor in order to detect chatter vibration generated in the workpiece W or the processing tool T being processed. Yes. The vibration detection sensor 500 is held by the workpiece holding unit 70 that holds the workpiece W. A detection signal output from the vibration detection sensor 500 is amplified by the amplifier 510 and then input to the FFT analyzer 520. The FFT analyzer 520 performs monitoring by frequency analysis of the detection signal output from the vibration detection sensor 500. The vibration detection sensor 500, the amplifier 510, and the FFT analyzer 520 constitute a vibration detection unit.

The controller 400 according to this embodiment includes a CPU 420 and a memory 430 connected to the bus line 410. The memory 430 includes NC data indicating machining conditions used in each of a plurality of steps for machining a workpiece, and a program for controlling the workpiece machining process.

When the controller 400 receives from the FFT analyzer 520 data indicating that chatter vibration having an amplitude greater than the specified intensity has been detected, the controller 400 executes processing for correcting the machining conditions in the current process to suppress chatter vibration in the current process. To do. Also, based on the vibration data of the workpiece W in the current process, it is predicted whether chatter vibration will occur in the next process. If chatter vibration is predicted to occur, the NC data indicating the machining conditions in the next process should be corrected. Do.

  FIG. 5 shows a processing flow in the controller 400 of the present embodiment. In the following description, a case where the workpiece W is processed by three processes (roughing, intermediate finishing, and finishing) will be described, but the number of processes is not limited to three.

(Roughing)
When rough machining of a workpiece is started in the chatter vibration prediction preventing machining apparatus of the present embodiment, the CPU 420 provided in the controller 400 is activated, and a program that is input in advance into the memory 410 and controls the machining processing of the workpiece is read ( Step S10). Then, the program is started, and the machining tool T starts cutting the workpiece W based on the NC data for rough machining previously input to the memory 430 (step S11). During cutting of the workpiece W, vibration data of the workpiece W is acquired by the vibration detection sensor 500 (step S12).

  After the machining is started, the controller 400 checks in real time whether or not the signal that detects chatter vibration in the machining tool T and the workpiece W is received from the FFT analyzer 520 (step S13). When the signal for detecting chatter vibration has not been received (in the case of NO), in the program, the roughing is performed until the workpiece W becomes the final shape in the process, and the process ends (step S15).

  In step S13, when a signal indicating chatter vibration has been received (in the case of YES), first, NC data for rough machining is performed so that the one-blade feed amount of the machining tool T is increased by a predetermined amount. Is corrected (step S14). Then, Steps S10 to S12 are repeated, and it is confirmed again whether or not a signal for detecting chatter vibration in the processing tool T or the workpiece W is received from the FFT analyzer 520 (Step S13). As a result, if the signal for detecting chatter vibration has not been received, the program finishes the machining process until the rough machining is performed on the workpiece W to the final shape in the process (step S15). On the other hand, when the chatter signal is continuously detected, that is, when chatter vibration is not suppressed by the machining tool T or the workpiece W, the cutting speed of the workpiece by the machining tool T is set in advance. The NC data for roughing is corrected so as to decrease by the amount (step S14). In this case, it is necessary to extend the machining process in the program in order to compensate for the machining speed delay caused by the reduced cutting speed. Then, Steps S10 to S12 are repeated, and it is confirmed again whether or not a signal for detecting chatter vibration in the processing tool T or the workpiece W is received from the FFT analyzer 520 (Step S13). As a result, if the signal for detecting chatter vibration has not been received, the program finishes the machining process until the rough machining is performed on the workpiece W to the final shape in the process (step S15). Furthermore, when the chatter signal is continuously detected, that is, when chatter vibration is not suppressed by the machining tool T or the workpiece W, the amount of cutting per workpiece by the machining tool T is determined in advance. The NC data for roughing is corrected so as to decrease by the set amount (step S14). In this case, it is necessary to extend the machining process in the program in order to compensate for the machining speed delay caused by the reduced cutting amount. Then, Steps S10 to S12 are repeated, and it is confirmed again whether or not a signal for detecting chatter vibration in the processing tool T or the workpiece W is received from the FFT analyzer 520 (Step S13). As a result, if the signal for detecting chatter vibration has not been received, the program finishes the machining process until the rough machining is performed on the workpiece W to the final shape in the process (step S15). The finally corrected NC data for roughing is stored in the memory 430 (step S60).

  Further, in the rough machining in the present embodiment, based on the NC data for rough machining finally corrected and the vibration data acquired at the time of workpiece machining, at the time of intermediate finishing machining, which is the next process with higher finishing accuracy. Predicts chatter vibration. Based on this prediction, the NC data for medium finishing machining, which is the machining condition at the time of medium finishing, is corrected (step S20). However, step S20 does not need to be performed at the same time during the roughing process, and may be completed before the intermediate finishing process is started when the roughing process and the intermediate finishing process are performed discontinuously.

  Fig. 6 shows the prediction of chattering during intermediate finish machining based on the final rough machining NC data during rough machining and workpiece vibration data during rough machining, and NC data during intermediate finish machining is based on this prediction result. The detailed flow of step S20 which corrects is shown.

  In step S20, first, the cutting force for the workpiece to be machined during rough machining is calculated from the machining conditions based on the NC data finally corrected at the time of rough machining and the specific cutting resistance of the workpiece to be machined. (Step S21).

  Next, the dynamic rigidity of the workpiece to be machined during rough machining is calculated from the cutting force for the workpiece to be machined obtained in step S21 and the vibration data of the workpiece to be machined obtained during rough machining (step S22). .

  Next, the dynamic stiffness K of the workpiece to be machined during intermediate finishing is obtained from the dynamic stiffness at the time of rough machining for the workpiece to be machined obtained in step S22 and the CAD data of the workpiece to be machined during intermediate finishing. Calculated (step S23).

  The dynamic stiffness K of the workpiece to be processed obtained here is used to obtain a curve of “work dynamic stiffness K” in FIG. 8 showing the correlation between the stability limit of chatter vibration and the machining conditions. The lower left region from this curve is a stable region, and theoretically no chatter vibration occurs. The hatched area in the upper right of this curve is an unstable area, and theoretically chatter vibration occurs.

  Next, the dynamic rigidity K at the time of intermediate finishing for the workpiece to be machined obtained in step S23 and the machining conditions of the workpiece to be machined at the time of intermediate finishing (NC data such as the feed rate, cutting speed, cutting depth, etc.) ) Is matched. As a result, it is determined whether the machining conditions during the finishing process are in the “stable region” or “unstable region” in FIG. 8 with respect to chatter vibrations, and chatter vibrations are generated during the finishing process. Predicted (step S24). If the machining conditions during the intermediate finishing process are in the “unstable region” with respect to chatter vibration, the NC data in the intermediate finishing process is corrected (step S25). In step S25, for example, if the NC data at the time of intermediate finishing is present at the position of the x mark in case 1, the speed ratio of the NC data (inversely proportional to the one-blade feed value) is indicated by a circle in the stable region along the arrow. The one-blade feed value in the NC data during the finishing process is corrected in the increasing direction so as to decrease to the position. Also, for example, when the NC data at the time of semi-finishing at the present is present at the position of the X mark of the case 2, the speed ratio and cutting speed of the NC data are reduced to the position of the circle mark in the stable region along the arrow. As described above, the one-blade feed value and the cutting speed value in the NC data at the time of intermediate finishing are corrected in the increasing and decelerating directions, respectively.

  On the other hand, when the machining condition during the intermediate finishing process is in the “stable region” with respect to chatter vibration, the NC data in the intermediate finishing process is not corrected (step S26).

  The rough processing flow has been described above, but many actual workpieces have a three-dimensional shape such as a blade or an impeller. Since the rigidity of a three-dimensional workpiece varies depending on the machining point, the machining process is performed at a plurality of predetermined points on the workpiece.

(Medium finishing)
The processing flow during intermediate finishing is basically the same as the processing flow during rough machining.

  When the workpiece finishing process is started in the chatter vibration prediction preventing machining apparatus of the present embodiment, the CPU 420 provided in the controller 400 is activated to read a program for controlling the machining process of the workpiece (step S30). Then, the machining tool T cuts the workpiece W based on the NC data for intermediate finishing that has been input to the memory 430 in advance or has been corrected based on the roughing processing that was the previous step. Processing is started (step S31). During cutting of the workpiece W, vibration data of the workpiece W is acquired by the vibration detection sensor 500 (step S32).

After the machining is started, the controller 400 checks in real time whether or not the signal having detected chatter vibration in the machining tool T and the workpiece W is received from the FFT analyzer 520 (step S33). When the signal for detecting chatter vibration has not been received (in the case of NO), in the program, the finishing process is carried out until the intermediate finishing process forms the workpiece W into the final shape in the process (step S35).

  In step S33, if a signal causing chatter vibration is received (in the case of YES), first, NC data for intermediate finishing machining is performed so that the feed amount of the machining tool T is increased by a predetermined amount. Is corrected (step S34). Then, Steps S30 to S32 are repeated, and it is confirmed again whether or not a signal for detecting chatter vibration is received from the processing analyzer T or the workpiece W from the FFT analyzer 520 (Step S33). As a result, if the signal for detecting chatter vibration has not been received, the program finishes the machining process until the intermediate finishing is finished with the workpiece W having the final shape in the process (step S35). On the other hand, when the chatter signal is continuously detected, that is, when chatter vibration is not suppressed by the machining tool T or the workpiece W, the cutting speed of the workpiece by the machining tool T is set in advance. The NC data for the finishing process is corrected so as to decrease by the amount (step S34). In this case, it is necessary to extend the machining process in the program in order to compensate for the machining speed delay caused by the reduced cutting speed. Then, Steps S30 to S32 are repeated, and it is confirmed again whether or not a signal for detecting chatter vibration is received from the processing analyzer T or the workpiece W from the FFT analyzer 520 (Step S33). As a result, if the signal for detecting chatter vibration has not been received, the program finishes the machining process until the intermediate finishing is finished with the workpiece W having the final shape in the process (step S35). Furthermore, when the chatter signal is continuously detected, that is, when chatter vibration is not suppressed by the machining tool T or the workpiece W, the amount of cutting per workpiece by the machining tool T is determined in advance. The NC data for intermediate finishing is corrected so as to decrease by the set amount (step S34). In this case, it is necessary to extend the machining process in the program in order to compensate for the machining speed delay caused by the reduced cutting amount. Then, Steps S30 to S32 are repeated again, and it is confirmed again whether or not a signal for detecting chatter vibration in the processing tool T or the workpiece W is received from the FFT analyzer 520 (Step S33). As a result, if the signal for detecting chatter vibration has not been received, the program finishes the machining process until the intermediate finishing is finished with the workpiece W having the final shape in the process (step S35). The NC data for final finishing that has been finally corrected is stored in the memory 430 (step S60).

  Further, in the intermediate finishing in the present embodiment, the finishing process, which is the next process with higher finishing accuracy, is based on the NC data for final finishing intermediate machining and the vibration data acquired during workpiece processing. Predicts chatter vibrations. Based on this prediction, the NC data for finishing machining, which is a machining condition at the time of finishing machining, is corrected (step S40). However, step S40 does not need to be performed at the same time as the intermediate finishing process, and may be completed before the finishing process is started when the intermediate finishing process and the finishing process are performed discontinuously.

  Fig. 7 shows the prediction of chattering during finishing using the final NC data for intermediate finishing and workpiece vibration data during intermediate finishing. Based on the prediction results, the NC during finishing The detailed flow of step S40 which corrects data is shown.

  In step S40, first, the cutting force for the workpiece to be machined during the intermediate finish machining is calculated from the machining conditions based on the NC data finally corrected at the time of the intermediate finish machining and the specific cutting resistance of the workpiece to be machined. (Step S41).

  Next, the dynamic rigidity of the workpiece to be machined during the intermediate finishing process is calculated from the cutting force for the workpiece to be machined obtained in step S41 and the vibration data of the workpiece to be machined obtained during the intermediate finishing process (step S42).

  Next, the dynamic stiffness K of the workpiece to be machined during finishing machining is calculated from the dynamic stiffness at the time of medium finishing machining for the workpiece to be machined obtained in step S42 and the CAD data of the workpiece to be machined at the time of finishing machining. (Step S43). The dynamic stiffness K of the workpiece to be processed obtained here is used to obtain a curve of “work dynamic stiffness K” in FIG. 8 showing the correlation between the stability limit of chatter vibration and the machining conditions. The lower left region from this curve is a stable region, and theoretically no chatter vibration occurs. The hatched area in the upper right of this curve is an unstable area, and theoretically chatter vibration occurs.

  Next, the dynamic stiffness K at the time of finishing machining for the workpiece to be machined obtained in step S43, and the machining conditions of the workpiece to be machined at the time of finishing machining (NC data such as a one-blade feed amount, a cutting speed, and a cutting amount) and Are matched. As a result, it is determined whether the machining condition during finishing is in the “stable region” or “unstable region” in FIG. 8 with respect to chatter vibration, and occurrence of chatter vibration during finishing is predicted. (Step S44). Then, when the machining condition at the time of finishing is in the “unstable region” with respect to chatter vibration, the NC data in the finishing process is corrected (step S45). On the other hand, when the machining condition at the finishing machining is in the “stable region” with respect to chatter vibration, the NC data is not corrected in the finishing process (step S46).

  The processing flow of the intermediate finish processing has been described above, but many actual workpieces have a three-dimensional shape such as a blade or an impeller. Since the rigidity of a three-dimensional workpiece varies depending on the machining point, the machining process is performed at a plurality of predetermined points on the workpiece.

(Finishing)
The processing flow during finishing is basically the same as the processing flow during roughing and intermediate finishing. When workpiece finishing is started in the chatter vibration prediction preventing machining apparatus according to the present embodiment, the CPU 420 provided in the controller 400 is activated to read a program for controlling workpiece machining (step S50). Then, the machining tool T starts cutting the workpiece W based on the NC data for finishing that has been entered in the memory 430 in advance, or has been corrected based on the processing at the time of the intermediate finishing that is the previous process. Processing is started (step S51). During cutting of the workpiece W, the vibration detection sensor 500 acquires vibration data of the workpiece W (step S52).

After the machining is started, the controller 400 checks in real time whether or not the signal that detects chatter vibration in the machining tool T and the workpiece W is received from the FFT analyzer 520 (step S53). When the signal for detecting chatter vibration has not been received (in the case of NO), in the program, the finishing process is performed until the workpiece W has a final shape in the process, and the process ends (step S55).

  If a signal causing chatter vibration is received in step S53 (in the case of YES), first, the NC data for finishing machining is set so that the feed amount of the cutting tool T is increased by a predetermined amount. Is corrected (step S54). Then, Steps S50 to S52 are repeated, and it is confirmed again whether or not a signal for detecting chatter vibration is received from the processing analyzer T or the workpiece W from the FFT analyzer 520 (Step S53). As a result, if the signal for detecting chatter vibration has not been received, the processing is finished until the finish processing of the workpiece W becomes the final shape in the process in the program (step S55). On the other hand, when the chatter signal is continuously detected, that is, when chatter vibration is not suppressed by the machining tool T or the workpiece W, the cutting speed of the workpiece by the machining tool T is set in advance. The NC data for finishing is corrected so as to decrease by the amount (step S54). In this case, it is necessary to extend the machining process in the program in order to compensate for the machining speed delay caused by the reduced cutting speed. Then, Steps S50 to S52 are repeated, and it is confirmed again whether or not a signal for detecting chatter vibration is received from the processing analyzer T or the workpiece W from the FFT analyzer 520 (Step S53). As a result, if the signal for detecting chatter vibration has not been received, the processing is finished until the finish processing of the workpiece W becomes the final shape in the process in the program (step S55). Furthermore, when the chatter signal is continuously detected, that is, when chatter vibration is not suppressed by the machining tool T or the workpiece W, the amount of cutting per workpiece by the machining tool T is determined in advance. The NC data for finishing is corrected so as to decrease by the set amount (step S54). In this case, it is necessary to extend the machining process in the program in order to compensate for the machining speed delay caused by the reduced cutting amount. Then, Steps S50 to S52 are repeated again, and it is confirmed again whether or not a signal for detecting chatter vibration in the processing tool T or the workpiece W is received from the FFT analyzer 520 (Step S53). As a result, if the signal for detecting chatter vibration has not been received, the processing is finished until the finish processing of the workpiece W becomes the final shape in the process in the program (step S55). The finally corrected NC data for finishing is stored in the memory 430 (step S60).

  The processing flow for finishing has been described above, but many actual workpieces have a three-dimensional shape such as a blade or an impeller. Since the rigidity of a three-dimensional workpiece varies depending on the machining point, the machining process is performed at a plurality of predetermined points on the workpiece.

  In the chatter vibration prediction preventing apparatus according to the present embodiment, the flow of performing the three processing processes of “roughing”, “medium finishing”, and “finishing” has been described. In the above processing flow, the chatter vibration in the next process is predicted and the NC data in the next process is sequentially corrected based on the vibration data in the current process. For example, based on the vibration data in rough machining, Not only can the NC data be corrected by predicting chatter vibration during intermediate finishing, but at the same time, the NC data can also be corrected by predicting chatter vibration during finishing.

  As described above, in the present embodiment, not only chatter vibration in the current process is prevented, but also occurrence of chatter vibration in the next process is predicted based on vibration data during machining of the workpiece in the current process. And chatter vibration in the next process is prevented by correcting the processing conditions of the next process. Thereby, it is possible to perform efficient cutting without reducing chatter vibration and reducing the processing speed individually for each process. In addition, the vibration data of the workpieces in multiple processes are used sequentially to correct the machining conditions in the next process or the next process to prevent chatter vibrations in subsequent processes. Prevention can be realized. In this way, the prevention of chatter vibration over the entire machining of the workpiece is realized, so that the quality of the workpiece machining surface during finishing can be improved.

  Further, by providing the machining center with the chatter vibration prediction preventing processing device of the present embodiment, high-speed and high-efficiency processing can be realized.

It is a figure which shows the structure of the conventional workpiece | work processing apparatus. It is a figure which shows the structure regarding the vibration detection of the conventional workpiece | work processing apparatus. It is a figure which shows the processing flow when chatter vibration is detected with the conventional workpiece | work processing apparatus. It is a figure which shows the structure regarding the vibration detection of the chatter vibration prediction prevention processing apparatus concerning embodiment of this application. It is a figure which shows the flow of the process of the workpiece | work in the chatter vibration prediction prevention processing apparatus concerning embodiment of this application. It is a figure which shows the flow which estimates the chatter vibration generation | occurrence | production in the next process in the chatter vibration prediction prevention processing apparatus concerning embodiment of this application (step S20). It is a figure which shows the flow which estimates the chatter vibration generation | occurrence | production in the next process in the chatter vibration prediction prevention processing apparatus concerning embodiment of this application (step S40). It is a figure which shows the correlation with the stability limit of chatter vibration, and processing conditions.

Explanation of symbols

2 ... Base 4 ... Table 5 ... Block 6 ... Rotating mechanism 7, 70 ... Work holding unit 8, 80 ... Processing tool holding unit 10 ... Work processing device 20 ... Work bench 30 ... Processing head 40, 400 ... Controller 50, 500 ... Vibration detection sensors 51, 510 ... Amplifiers 52, 520 ... FFT analyzer 410 ... Bus line 420 ... CPU
430 ... Memory T ... Machining tool W ... Workpiece

Claims (12)

Acquiring vibration data of the workpiece in the current process;
Preventing chatter vibration of the workpiece in the current process based on the vibration data of the workpiece acquired in the acquiring step;
Furthermore, using the vibration data of the workpiece acquired in the acquiring step, predicting the presence or absence of chatter vibration in the next process with higher finishing accuracy,
A chatter vibration prediction preventing method comprising: correcting machining data for machining the workpiece in the next process based on the chatter vibration occurrence result predicted in the predicting step. The chatter vibration prediction preventing method according to claim 1, wherein the predicting step includes:
A first calculation step of calculating a cutting force for the workpiece in the current process from machining data for machining the workpiece in the current process and a specific cutting resistance of the workpiece;
A second calculation step for calculating the dynamic rigidity of the workpiece in the current process from the cutting force and the vibration data calculated in the first calculation step;
A third calculation step for calculating the dynamic stiffness K of the workpiece in the next step based on the dynamic stiffness calculated in the second calculation step and the CAD data of the workpiece in the next step;
Predicting the occurrence of chatter vibration in the next process by comparing the value of the dynamic stiffness K of the work in the next process calculated in the third calculation step with the machining data for processing the work in the next process A chatter vibration prediction preventing method comprising the steps of:   The chatter vibration prediction preventing method according to claim 1 or 2, wherein the chatter vibration prediction preventing method is performed at a plurality of machining positions of the workpiece. A step of holding the workpiece by the workpiece holding unit;
(1) Based on machining data, machining the workpiece held in the holding step with a machining tool for machining the workpiece;
(2) The vibration detection unit installed in the workpiece holding unit acquires vibration data of the workpiece while the workpiece is being processed in the processing step in the current process;
(3) preventing chatter vibration of the workpiece in the current process based on the vibration data of the workpiece acquired in the acquiring step;
(4) Furthermore, using the vibration data of the workpiece acquired in the acquiring step, predicting the occurrence of chatter vibration in the next process with higher finishing accuracy;
(5) correcting the machining data for machining the workpiece in the next process based on the chatter vibration occurrence result predicted in the predicting step, and finally performing the steps (1) to (5) And a step of repeatedly performing the process up to the process of finishing accuracy. 5. The workpiece machining method according to claim 4, wherein the step of predicting comprises:
A first calculation step of calculating a cutting force for the workpiece in the current process from machining data for machining the workpiece in the current process and a specific cutting resistance of the workpiece;
A second calculation step for calculating the dynamic rigidity of the workpiece in the current process from the cutting force and the vibration data calculated in the first calculation step;
A third calculation step for calculating the dynamic stiffness K of the workpiece in the next step based on the dynamic stiffness calculated in the second calculation step and the CAD data of the workpiece in the next step;
Predicting the occurrence of chatter vibration in the next process by comparing the value of the dynamic stiffness K of the work in the next process calculated in the third calculation step with the machining data for processing the work in the next process A workpiece machining method comprising the steps of:   6. The workpiece machining method according to claim 4, wherein the workpiece machining method is performed at a plurality of machining positions of the workpiece. A work holding unit for holding a work;
A processing tool holding unit for holding a processing tool for processing the workpiece based on the processing data of the current process;
A vibration detection unit that is installed in the workpiece holding unit and acquires vibration data of the current process of the workpiece while the workpiece is being processed by the processing tool;
Based on the vibration data of the workpiece acquired in the vibration detection unit, chatter vibration of the workpiece in the current process is prevented, and further, the vibration data of the current process of the workpiece acquired by the vibration detection unit A chatter comprising: a controller that predicts the occurrence of chatter vibration in the next process with higher finishing accuracy and corrects the machining data of the next process for machining the workpiece in the next process based on the prediction result Vibration prediction prevention processing equipment. The chatter vibration prediction preventing processing apparatus according to claim 7, wherein the controller includes:
CPU and memory,
The memory includes a program for machining the workpiece and machining data corresponding to each of a plurality of steps.
The CPU, based on the program, the cutting force on the work in the current process from the machining data of the work in the current process and the specific cutting resistance of the work,
From the vibration data and the cutting force, the dynamic rigidity of the workpiece in the current process,
Based on the dynamic stiffness and the CAD data of the workpiece in the next step, the dynamic stiffness K of the workpiece in the next step is calculated,
Predicting the presence or absence of chatter vibration in the next process by comparing the value of the dynamic rigidity K of the work in the next process with the machining data for processing the work in the next process, and based on the prediction result A chatter vibration prediction preventing processing device for correcting the processing data for processing the workpiece in a next step.   9. The chatter vibration prediction preventing processing device according to claim 7 or 8, wherein the processing data of the next process for processing the workpiece is corrected at a plurality of processing positions of the workpiece.   A machining center comprising the chatter vibration prediction preventing processing device according to any one of claims 7 to 9. A workpiece holding unit for holding a workpiece; a machining tool holding unit for holding a machining tool for machining the workpiece based on machining data of the current process; and the workpiece installed in the workpiece holding unit, wherein the workpiece is the machining tool A vibration detection unit that acquires vibration data of the current process of the workpiece while being processed at a workpiece, and chatter vibration of the workpiece in the current process based on the vibration data of the workpiece acquired by the vibration detection unit Further, using the vibration data of the current process of the workpiece acquired by the vibration detection unit, predicting the occurrence of chatter vibration in the next process with higher finishing accuracy, and based on the prediction result A chatter vibration prediction preventing processing device comprising a controller that corrects processing data of the next process for processing the workpiece in the next process A Erareru chatter vibration prediction prevention program,
The controller includes a CPU and a memory, and the memory includes the vibration prediction prevention program and machining data corresponding to each of a plurality of steps.
When power is supplied to the chatter vibration prediction preventing processing device, the CPU reads the vibration prediction preventing program from the memory, and the processing data corresponding to the current process and the specific cutting resistance of the workpiece are used to determine the current process. Based on the cutting force on the workpiece, the vibration data and the cutting force, the dynamic stiffness of the workpiece in the current step, and the dynamic stiffness and the CAD data of the workpiece in the next step, the workpiece in the next step Calculate the dynamic stiffness K,
Furthermore, the presence or absence of chatter vibration in the next process is predicted by comparing the value of the dynamic stiffness K of the work in the next process with the machining data for processing the work in the next process, and based on the prediction result A chatter vibration prediction preventing program for correcting machining data of the next process for machining the workpiece in the next process.   12. The chatter vibration prediction preventing program according to claim 11, wherein the processing data of the next process for machining the workpiece is corrected at a plurality of machining positions of the workpiece.

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