DE112020004994T5 - Process and system for monitoring the processing status of a working machine - Google Patents

Abstract

There is a step of detecting machining vibration in machining, a step of obtaining a machining frequency by analyzing machining vibration by Fourier series expansion, a step of dividing the machining frequency into a tool pass frequency and a residual frequency, and a step of monitoring the machining state by a comparison display of the tool pass frequency and the residual frequency.

Description

[Technical Field]

The present invention relates to a method and system for monitoring the machining state of a working machine for monitoring the machining state of the workpiece when machining processing is performed on a workpiece by a rotating tool.

[background technology]

In general, various machine tools are used to perform machining processing on a workpiece by a machining tool. For example, drilling machining is machining a high-precision hole at a specified position with the cutting edge diameter of a boring tool on which a cutting tool (cutting edge) for boring is provided, the boring tool being attached to a rotary main shaft (spindle) of a machine tool, and the drilling tool, while rotating at high speed, is successively guided along a pre-drilled hole.

In this type of work machine, the rotary main shaft, the machining tool or the workpiece are easily deflected due to the cutting resistance. This bending causes vibrations in the machining tool and workpiece, and these vibrations can appear as chatter (including so-called regenerative chatter) during machining. In particular, when machining a mold with a very long tool or efficiently machining a hard-to-machine material, suppressing or avoiding chatter is a big problem.

For example, a method and an apparatus for suppressing chattering of a working machine disclosed in Patent Document 1 are known. This chatter suppressing method comprises a step of detecting vibrations occurring at the start of rotation of the machining tool or the workpiece, a step of setting the vibrations of the machine main shaft at idle as a threshold value, a step of judging whether machining vibration of the machine main shaft detected in machining exceeds the threshold, and a step in which, when it is judged that the machining vibration exceeds the threshold, the machining vibration is analyzed by Fourier series expansion, and the rotational speed of the machine main shaft adjusted using the calculation formula of frequency × 60 ÷ number of cutting edges (or multiples thereof).

As a result, vibrations are detected from the beginning of the rotation and analyzed using the Fourier series development. The calculation in the Fourier series expansion is simple and prompt processing is possible, so that the speed is positively improved and chatter vibrations can be predicted before chatter has actually developed. As a result, regenerative chatter whose oscillations develop from zero with the start of rotation can be detected as soon as possible at the stage of prediction. Therefore, the rotational speed of the engine main shaft can be adjusted before being affected by an actual chatter, and it is possible to reliably suppress the generation of a regenerative chatter.

[Prior Art Documents]

[patent document]

[Patent Document 1]

Patent No. JP 5105102 B2

[Outline of the Invention]

[Problem to be solved by the invention]

The present invention has been made with reference to the above technical idea and has as an object to provide a method and a system for monitoring the machining state of a working machine, in which various machining states can be recognized with high precision and efficiently through simple steps and a simple structure .

[means for solving the task]

The present invention relates to a method and system for monitoring the machining state of a working machine for monitoring the machining state of the workpiece when machining processing is performed on a workpiece by a rotating tool.

This method for monitoring the machining status has a step for detecting machining vibrations during machining by a rotating tool, a Step of obtaining a machining frequency (frequency of machining vibrations generated during machining) by analysis of machining vibrations using Fourier series expansion, a step of converting the machining frequency into a tool passing frequency (TPF) (Tool Passing Frequency), which is the Sum of a fundamental calculated from main shaft speed × number of cutting edges ÷ 60 and their harmonics (integer multiple of the relevant fundamental), and residual frequencies (NON-TPF) after subtracting the tool pass frequency from the total machining frequency, and a step for monitoring the machining status of a workpiece through a comparative display of the tool pass frequency and the residual frequencies.

Further, the system for monitoring the machining status includes a vibration detection mechanism for detecting machining vibrations when machining by a rotating tool, a computing mechanism for obtaining a machining frequency (frequency of machining vibrations that arise during machining) by analyzing the machining vibrations using Fourier series expansion, a Frequency divider mechanism by which the machining frequency is converted into a tool passing frequency (TPF) (Tool-Passing-Frequency), which is the sum of a fundamental calculated from main shaft speed × number of cutting edges ÷ 60 and their harmonics (integer multiple of the relevant fundamental), and residual frequencies (NON-TPF) after subtracting the tool pass frequency from the total machining frequency, and a frequency comparison display mechanism for monitoring the machining status of a workpiece a comparison display of the tool pass frequency and the residual frequencies.

[Effects of the invention]

In the method and system for monitoring the machining state of a working machine according to the present invention, when machining processing is performed on a workpiece by a rotating tool, the machining frequency (frequency of machining vibration) is divided into two parts, namely, a tool pass frequency (TPF) and other residual frequencies (NON- TPF), whereby different machining statuses of the workpiece can be monitored only through the comparison display of the tool passage frequency and the residual frequencies.

In addition, only by using the TPF vibration and NON-TPF vibration of the main shaft rotation speed and the number of cutting edges as two parameters, the quality of comprehensive machining can be judged, and differentiation of the quality of the machining state can be carried out with high precision and efficiently.

character list

• [ 1 ] 1 12 is a schematic explanatory view of a machine tool to which the machining state monitoring system of a machine tool according to a first embodiment of the present invention is applied.
• [ 2 ] 2 Fig. 14 is an explanatory view of a controller constituting the machining state monitoring system.
• [ 3 ] 3 Fig. 12 is an explanatory view of a display unit constituting the machining status monitoring system.
• [ 4 ] 4 14 is an explanatory view of a comparison between the case where the quality of the cutting state is indicated by the current value of a cutting load and the case where the quality of the cutting state is indicated by the second embodiment of the present invention.
• [ 5 ] 5 14 is an explanatory view showing a frequency spectrum in machining vibrations of the third embodiment of the present invention.

[Forms for carrying out the invention]

As in 1 1, a machining status monitoring system 10 according to the first embodiment of the present invention is applied to a machine tool 12. As shown in FIG. The machine tool 12 is applied to a work machine of a system in which an acceleration sensor 26, a microphone 28, and a controller 30, which will be described later, are functionally integrated.

The machine tool 12 includes a spindle (main shaft) 18 rotatably provided in a housing 14 via a bearing 16 and a tool holder (rotary tool) 20 detachably attached to the spindle 18 . At the front end of the tool holder 20, a cutting tool 22 is mounted. A workpiece W lies on a work table 24.

The system 10 for monitoring the machining status includes for the detection of Vibrations of the spindle 18 idling and vibrations generated when the cutting tool 22 starts machining, at least one of an acceleration sensor (vibration detection mechanism) 26 mounted on a side section of the housing 14 and a microphone (vibration detection mechanism) 28 , which acquires vibrational noise through sound waves. The accelerometer 26 and (or) the microphone 28 is connected to the controller 30 and the controller 30 is connected to a machine tool control panel 32 . The machine tool control panel 32 is used to control the machine tool 12 and is connected to a control panel 34 .

As in 2 As shown, the controller 30 includes an arithmetic unit (arithmetic mechanism) 38 that amplifies and imports mechanical vibrations (machining vibrations) detected by the acceleration sensor 26 and (or) the microphone 28 by means of an amplifier and filter circuit 36 .

An input setting unit 40 for inputting the rotational speed of the spindle 18, the number of cutting edges, natural frequency etc. of the cutting tool 22 etc. is connected to the arithmetic unit 38 . In the input setting unit 40, a threshold for monitoring or detection judgment, a processing order of signals when vibration exceeding the threshold occurs, etc. are settable. A repetition counter (circuit) 42 is provided at the input setting unit 40 as needed.

On the arithmetic unit 38, there are a machining state judging unit 44 and an input/output unit 46 for outputting a signal subjected to arithmetic judgment processing explained below. Information on a main shaft speed RPM and the tool number used is transferred from the machine tool control panel 32 to the arithmetic unit 38 via the input/output unit 46 and can be read out by an NC program at any time. If macroscopic monitoring is carried out, only the number of tool cutting edges and a numerical value of the repetition counter 42 can also be entered separately as a threshold value.

A display unit 48 that displays a calculation result, a detection result, etc. on a screen is connected to the calculation unit 38 . Updated data is normally sent from the arithmetic unit 38 to the machining status assessment unit 44 every second.

As in 3 shown, the display unit 48 includes a total power display window 51, a frequency spectrum display window 52, a LPF vibration display window 53, a NON-TPF vibration display window 54 and a changes display window 55. At the left end of the display unit 48 are screens - Selection buttons 56, 57 are provided, which are used to switch between the display screen and the threshold entry screen. The arithmetic unit 38 acts as a frequency dividing mechanism that divides a frequency spectrum into a tool pass frequency and residual frequencies as described below.

The total power display window 51 is a vibration amount monitoring unit, which is turned ON by an unillustrated measurement start button of the controller 30 or a signal from a device. The cumulative power display window 51 displays a cumulative power (G ² ) of the vibrations changing along with the machining, with the magnitude of the amount of vibration in each time frame as a cumulative power having real-timeness.

In the case of the total power display window 51, the longitudinal axis represents the sum of the squared values of the acceleration and the transverse axis represents the course of time (second). In the case of the total power display window 51, a prediction threshold value 61 that indicates the prediction that the total power enters a warning range and sets an alarm threshold 62 indicating that total power has increased abnormally.

The frequency spectrum display window 52 displays the frequency spectrum obtained by Fourier transforming the machining vibrations. In the frequency spectrum display window 52, the longitudinal axis represents the acceleration (G or m/s ² ) and the transverse axis represents the frequency (Hz) calculated by Fourier transform. The display range of the spectrum transverse axis is selective between 10 Hz to 10,000 Hz in advance is set, generally selecting 10 Hz to 2,000 Hz, 10 Hz to 2,500 Hz, or 10 Hz to 4,000 Hz, etc. expressing a good machining state. Long axis display is an automatic gain formula.

In the frequency spectrum display window 52, an alarm threshold value 63 and a threshold line 69 of a restriction area are set as necessary. The threshold line 69 can be adjusted for a particular frequency band, with adjustment of the threshold of that frequency band adjusting the height of that frequency band range at a separate input settings screen (not shown).

The LPF vibration display window 53 displays the Tool Passing Frequency (hereinafter TPF) in the frequency spectrum displayed in the frequency spectrum display window 52 . TPF is the sum of a fundamental wave calculated by main shaft speed × number of cutting edges ÷ 60 and its harmonics (integer multiple of the relevant fundamental wave). In the LPF vibration display window 53, the longitudinal axis represents acceleration (G or m/s ² ) and the transverse axis represents frequency (Hz). In the LPF vibration display window 53, an alarm threshold 64 is set as needed.

The NON-LPF vibration display window 54 displays the residual frequencies (hereinafter NON-LPF) in the frequency spectrum after removing the LPF, which was displayed in the frequency spectrum display window 52. In the NON-TPF vibration display window 54, the longitudinal axis represents acceleration (G or m/s ² ) and the transverse axis represents frequency (Hz). Threshold 65 and a threshold line 68 of a restriction area are set. Threshold line 68, like threshold line 69, can be set for a particular frequency band, and as the threshold of that frequency band is set, the level of that frequency band range can be set on a separate input setup screen (not shown).

The change display window 55 functions as a frequency comparison display mechanism for monitoring the machining status of the workpiece W by comparing the LPF and NON-TPF. In the change display window 55, a change amount of the relative ratio between the total amount of the LPF displayed in the LPF vibration display window 53 and the total amount of NON-TPF displayed in the NON-TPF vibration display window 54 (total amount of NON-TPF /total amount of TPF) displayed as a dot graph chronologically (per second). In this dot graph, low numeric values indicate good machinability, while high numeric values indicate deterioration in machinability and the occurrence of chatter.

In the change display window 55, a prediction threshold value 66 for judging whether a prediction stage for quality judgment of the machining has come, and at least one of an upper threshold value 67a and a lower threshold value 67b for differentiating whether a machining abnormality has occurred are set as necessary . A separate entry screen (not shown) is used for entry of the threshold values, which entry screen is displayed by operation of the screen selection button 57 .

Next, the method of monitoring the machining state by the machining state monitoring system 10 having this structure will be explained.

As in 1 1, in the machine tool 12, the spindle 18 on which the tool holder 20 is mounted, at the front end of which the cutting tool 22 is mounted, is driven in rotation while being guided along a pre-drilled hole of the workpiece W. Then, the tool holder 20 moves relative to the pilot hole side of the workpiece W. Therefore, the cutting tool 22 rotates integrally with the tool holder 20, and the cutting tool 22 performs the machining on the inner wall surface of the workpiece W.

The controller 30 acquires the idle vibration of the spindle 18 by means of the acceleration sensor 26 and (or) the microphone 28 before starting machining, and sets this value as an allowable value (threshold value). Then the vibrations of the spindle 18 are imported into the arithmetic unit 38 via the amplifier and filter circuit 36 . When the imported vibration exceeds the allowable value, the arithmetic unit 38 judges that the machining has started. That is, the arithmetic unit 38 functions as a machining start detection mechanism for detecting that the machining of the workpiece W has started. The machining start detection mechanism may also be a mechanism that detects that a certain time has elapsed from the start of rotation of the spindle 18, or a mechanism that detects that the guide distance of the spindle 18 has reached a certain distance.

Next, the arithmetic unit 38 subjects the machining vibrations, which have been imported via an amplifier and filter circuit 36, to arithmetical analysis by means of Fourier transformation (Fourier series expansion). Specifically, the oscillations per time f(t)

expressed by f(t)=Z(a _j cos2πJt+b _j sin2πJt). where a _j is a Fourier coefficient of the harmonic cosine component of frequency J and b _j is a Fourier coefficient of the harmonic sine component of frequency J.

The Fourier coefficients related to the frequency J are subjected to a Fourier series expansion based on a _j = 1/2T∫f(t)cos(2πJt)dt and b _j = 1/2T∫f(t)sin(2πJt)dt. The integration interval is 0 to T, and this integration interval T is an integer multiple of the period 1/J. Here, a vibration frequency of, for example, 10 Hz to 10,000 Hz is obtained by actual machining.

As in 3 As shown, the total power display window 51, the frequency spectrum display window 52, the LPF vibration display window 53, the NON-LPF vibration display window 54 and the change display window 55 are provided on the display unit 48, wherein the signal generated by the Fourier Transform calculated frequency spectrum depending on the purpose herein is displayed.

Concretely, in the cumulative power display window 51, the magnitude of the vibration amount that changes along with the machining in each time frame is displayed as the cumulative power (G ² ) having real-timeness. Here, the longitudinal axis indicates the total power (G ² ) obtained from the square of the acceleration, with the increase/decrease ratio of the amount of machining vibration being expressed by a large amount of change. This means that small vibrations are displayed smaller and large vibrations are displayed larger.

In addition, the value displayed in the total power display window 51 is a value of the square of the waveform of the acceleration amplitude integrated by the time axis unit (usually 1 second) and includes all acquired frequencies. Therefore, the entire power energy, which is difficult to distinguish using the frequency spectrum, can be discriminated, enabling sensitive display of the increase/decrease in cutting resistance, the increase/decrease of high-frequency vibration, and so on.

In the frequency spectrum display window 52, the frequency spectrum obtained by Fourier transforming the machining vibrations is displayed. Then, in the LPF vibration display window 53, only the LPF in the frequency spectrum displayed in the frequency spectrum display window 52 is displayed, while in the NON-LPF vibration display window 54, the NON-LPF in the frequency spectrum after elimination of the LPF are displayed.

Next, in the change display window 55, a change amount of the relative ratio between the total amount of the LPF displayed in the LPF vibration display window 53 and the total amount of NON LPF displayed in the NON LPF vibration display window 54 (total amount of NON -TPF/total amount of TPF) displayed as a dot graph chronologically (per second). In the change display window 55, low numerical values of the dot graph indicate good machining, while high numerical values indicate deterioration in machinability and generation of chatter.

Thereby, in the first embodiment, there is an effect that by monitoring the amount of change of the upper and lower parts in the change display window 55, the quality of the cutting state can be macroscopically recognized at a glance. That is, only by means of the TPF vibration and NON-TPF vibration with the two parameters of the main shaft speed and the number of cutting edges, the quality of comprehensive machining can be distinguished, with simple control, the quality judgment of the machining state can be carried out with high precision and efficiently can be executed.

In general, in a mass production processing of components in a production factory, automation is sought in order to efficiently produce high-quality goods in a large quantity. Here, mass production of inferior goods can be suppressed by the first embodiment. Since macroscopic judgment is made only by comparing two values of the LPF vibration and the NON-TPF vibration based on the frequency of the machining vibration, various detection conditions such as setting threshold values, etc. are unnecessary and various abnormalities can be easily detected .

Furthermore, the prediction threshold value 66 is set in the changes display window 55 . Therefore, when the change ratio of total amount of NON-TPF/total amount of TPF increases and exceeds the prediction threshold value 66, it is judged that a prediction stage for quality judgment has come, so that e.g. B. the attention of the operator of the machine etc. can be attracted.

In addition, at least the upper threshold value 67a is provided in the changes display window 55 . When the change ratio of the total amount of NON-TPF/total amount of TPF abnormally increases and exceeds the upper threshold value 67a, an alarm signal is thereby sent to the separate repetition counter 42. When a signal input greater than or equal to the set integrated value is detected by the repeat counter 42, the display shows a Unit 48 of the controller 30 displays a macro alarm signal and outputs it to the outside via the input/output unit 46 .

For a signal exceeding the alarm threshold value, since the repetition counter 42 is provided and counts an integrated value per unit time, an abnormal alarm cannot be judged at a momentary noise, etc. However, if the retry counter value is set to 1, an abnormality judgment is output when the alarm threshold is exceeded once.

In addition, at least the lower threshold value 67b is provided in the changes display window 55 . As a result, when the change ratio of the total amount of NON-TPF/total amount of TPF abnormally decreases and falls below the lower threshold value 67b, an alarm signal is sent to the separate repetition counter 42.

In the first embodiment, as stated above, by the change ratio of the total amount of NON-TPF/total amount of TPF displayed in the change display window 55, macroscopic monitoring of the processing state can be performed. Moreover, by combining the change of the changes display window 55 with the changes displayed in the total power display window 51, the frequency spectrum display window 52, the LPF vibration display window 53 or the NON-LPF vibration display window 54, the processing status (cutting status, abnormality status, etc.) can be grasped more precisely and in more detail.

For example, it may happen that in the change display window 55 the change ratio of total amount of NON-TPF/total amount of LPF increases, and the number of times the threshold line 68 set in a high-frequency vibration band area is exceeded a restriction area in the NON-TPF vibration display window 54 increases. This indicates an increase in high-frequency components due to wear of the cutting tool 22, and can be used for an alarm signal for replacing the tool.

In addition, in the case that in the change display window 55 the magnitude of the change ratio of the total amount of NON-TPF/total amount of TPF has become abnormally large, machining abnormality is assumed, and in the case that total in the NON-TPF vibration -Display window 54 noticeable peak vibrations (vibrations exceeding the alarm threshold value 65) occur, the onset of regenerative chatter is detected.

Furthermore, in the case that in the change display window 55, the magnitude of the change ratio of total amount of NON-TPF/total amount of TPF has become abnormally small, and in the TPF vibration display window 53 peaks rise high (the alarm Threshold 64 exceeding vibration), the emergence of a separately excited chatter detected. On the other hand, when in the change display window 55 the magnitude of the change ratio of the total amount of NON-LPF/total amount of LPF has become abnormally large and there is no signal of a threshold exceeding the threshold line 69 set to a low frequency range of a restriction area is output.

4 14 is an explanatory view of a comparison between the case where the quality of the cutting state is indicated by the current value of a cutting load and the case where the quality of the cutting state is indicated in the second embodiment of the present invention.

This is a machining of an aluminum material (workpiece W) with a 4-flute, 16φ end mill (cutting tool 22) at a machining center (machine tool 12). The machining conditions are: turning speed N = 6200 mm/min ^-1 , feed speed f = 0.1 mm/cutter, side surface machining Ar = 0.5 mm. In 4 the oscillations and the chronological change of the current load from the first half machining without chatter to the second half machining in which regenerative chatter has occurred are shown.

Concretely, a display window 71 displays the total performance during editing. A display window 72 displays the current load amount of the main shaft during machining, with the longitudinal axis showing the magnitude of the current load, while the transverse axis shows the chronological progression. In a display window 73 of a second embodiment, the frequency spectrum of the vibrations is divided into LPF vibrations 73a and NON-LPF vibrations 73b in an integrated display format. The dark color portion in the first half represents the LPF vibrations 73a, and the light color portion in the second half represents the NON-LPF vibrations 73b. Here, the LPF vibrations 73a and the NON-LPF vibrations should Vibrations 73b in different different colors or a different color depth can be set. A display window 74 shows the state of changing total amount of NON-TPF/total amount of TPF.

Machining starts at 7.4 seconds, and after a chatter prediction range from 11.3 seconds, regenerative chatter arises from 11.7 seconds to 13.4 seconds. A striking chronological change in the magnitude of the cutting vibrations is indicated in the display window 71 by the display of the total power. In the first half of processing (from the start of processing to 11.3 seconds), chatter-free processing occurs, while in the second half of processing (from 11.7 seconds to 13.4 seconds), chatter occurs. There is a large difference between the vibration magnitude of the first half and the vibration magnitude of the second half.

In the display window 72 showing the current load magnitude of the main shaft during machining, the cutting load hardly changes from the start of machining to the end. Therefore, various processing states such as the quality, etc. of processing cannot be distinguished well.

On the other hand, in the display window 73, in the first half of the processing, LPF vibrations 73a are displayed as a dark portion, while in the second half of processing, NON-LPF vibrations 73b are displayed as a light portion. As a result, from this display, the machining range (TPF vibrations 73a) of the former half without chattering and the state of the latter half in which chattering occurs (NON-TPF vibrations 73b) can be clearly distinguished.

Also, in the display window 74, the state of change of total amount of NON-TPF/total amount of TPF is displayed. This display makes it easy to distinguish the chronological changes in the editing status, with the first half of the editing showing a good editing status of a low numeric value, while the second half of the editing showing the numeric value increasing and a transition from poor condition to chattering.

5 12 shows a frequency spectrum in machining vibration in a third embodiment of the present invention. In a display window 81, the longitudinal axis represents the magnitude of the vibration (acceleration) (G or m/s ² ) and the transverse axis represents the frequency (Hz). Under the cutting conditions a speed of the spindle 18 of 6200 rpm and 4 cutting edges of the cutting tool 22, three noticeable vibration peaks arise in the display window 81. Specifically, it is 413 Hz (TPF1) as the fundamental wave, 826 Hz (TPF2) as the harmonic of an integral multiple of the fundamental wave, and the peak frequency of 1240 Hz (TPF3).

The display window 82 extracts and displays only the fundamental wave and the harmonics (TPF1, LPF2 and LPF3) (LPF waves) from the frequencies of the frequency spectrum displayed in the display window 81. The display window 83 extracts and displays only the NON-TPF vibrations from the vibrations of the display window 81 from which the fundamental wave and the harmonics (TPF1, TPF2 and TPF3) have been removed.

Comparing the display window 82 and the display window 83, it is clear that the LPF vibrations displayed in the display window 82 are larger than the NON-LPF vibrations displayed in the display window 83. As a result, normal processing is differentiated.

In 5 a display window 84 displays a frequency spectrum in a chatter processing that subsequently occurred, wherein peak frequencies of 751 Hz and 1165 Hz stand out. These are NON-TPF vibrations. The display window 85 extracts only the LPF vibrations from the frequency spectrum displayed in the display window 84 and displays them. A display window 86 extracts and displays only the NON-LPF vibrations from the vibrations of the display window 84 from which the LPF vibrations have been removed.

Comparing display window 85 and display window 86, it is clear that the NON TPF vibrations displayed in display window 86 are greater than the LPF vibrations displayed in display window 85. This discriminates that it is abnormal machining in which regenerative chatter has occurred.

As a result, by dividing the machining vibration into two parts, namely, TPF vibration and NON-TPF vibration, and detecting the differences between them, the cutting state can be correctly differentiated. As with the display window 73 in 4 the two sections of TPF vibration and NON-TPF vibration integrated can be represented by different colors or different concentration. Further is the same as the display window 74 in 4 a representation by two relative change ratios of the TPF vibrations and NON-TPF vibrations possible.

[Industrial Application]

In the method and system for monitoring the machining status of a working machine according to the present invention, when machining processing is performed on a workpiece by a rotary tool, the machining frequency is divided into tool pass frequency (TPF) and residual frequencies (NON-TPF), only by the comparison display of tool pass frequency and the residual frequencies, various machining states of the workpiece can be monitored.

Reference List

10

System for monitoring a processing status

12

machine tool

14

Housing

18

spindle

20

tool holder

22

cutting tool

26

accelerometer

28

microphone

30

controllers

32

Machine Tool Control Panel

34

control panel

38

unit of account

40

input setting unit

44

Machining condition judging unit

46

input/output unit

48

display unit

51

Overall performance display window

52

Frequency spectrum display window

53

TPF vibration display window

54

NON-TPF vibration display window

55

Changes display window

71-74, 81-86

display window

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• JP 5105102 B2 [0006]

Claims (14)

A machining state monitoring method of a working machine by which, when machining processing is performed on a workpiece by a rotary tool, the machining state of the tool is monitored, characterized by a step of detecting machining vibrations in machining by the rotary tool, a step of obtaining a machining frequency by an analysis of the machining vibrations using Fourier series expansion, a step in which the machining frequency is converted into a tool passage frequency, which is the sum of a fundamental calculated from main shaft speed × number of cutting edges ÷ 60 and their harmonics (integer multiple of the fundamental in question), and residual frequencies after removing the tool passage frequency from the total machining frequency, and a step of monitoring the machining state of the workpiece by a comparison a Display of tool pass frequency and residual frequencies. Method for monitoring the processing status of a working machine claim 1 , characterized by a step in which the start of the machining of the workpiece by the rotating tool is detected. Method for monitoring the processing status of a working machine claim 1 or 2 , characterized in that the relative ratio between the total amount of tool pass frequency and the total amount of residual frequencies is displayed in a chronologically changing change display window, and based on the change display window the quality of machining of the workpiece is judged. Method for monitoring the processing status of a working machine claim 3 , characterized in that a prediction threshold value and an upper threshold value and a lower threshold value are set in the changes display window, when the relative ratio exceeds the prediction threshold value, it is judged that a prediction stage for quality judgment of the processing has occurred, and if the relative ratio at least exceeds the upper threshold or falls below the lower threshold, the occurrence of a machining abnormality is differentiated. Method for monitoring the processing status of a working machine claim 3 , characterized in that a total power of the vibrations changing with the machining is displayed in a total power display window, the frequency spectrum of the machining vibrations obtained by Fourier transformation is displayed in a frequency spectrum display window, the tool passage frequency in the frequency spectrum in a LPF vibration display display window is displayed, and the residual frequencies in the frequency spectrum are displayed in a NON-TPF vibration display window. Method for monitoring the processing status of a working machine claim 5 , characterized in that wear of the rotating tool is detected on the basis of the changes display window and the NON-TPF vibration display window. Method for monitoring the processing status of a working machine claim 5 , characterized in that regenerative chattering of the rotating tool is detected based on the changes display window and the NON-TPF vibration display window. Method for monitoring the processing status of a working machine claim 1 or 2 , characterized in that a first section displaying the total amount of tool pass frequency and a second section displaying the total amount of residual frequencies are displayed in a multicolored change display window in which different colors or different color depth changes chronologically, and the quality of the processing of the workpiece is differentiated by means of the multicolored changes display window. A working machine machining state monitoring system by which, when machining processing is performed on a workpiece by a rotating tool, the machining state of the tool is monitored, characterized by a vibration detecting mechanism for detecting machining vibration in machining by a rotating tool, an obtaining arithmetic mechanism a machining frequency through an analysis of the machining vibrations using Fourier series development, a frequency dividing mechanism by which the machining frequency is divided into a tool pass frequency, which is a fundamental calculated from main shaft speed × number of cutting edges ÷ 60 and its harmonic (integer multiple of the fundamental concerned), and residual frequencies after removing the tool pass frequency from the total machining frequency , and a frequency comparison display mechanism for monitoring the machining state of a workpiece by a comparison display of the tool pass frequency and the residual frequencies. System for monitoring the processing status of a working machine claim 9 characterized by a machining start detection mechanism by which the start of machining of the workpiece by the rotary tool is detected. System for monitoring the processing status of a working machine claim 9 or 10 characterized by a change display window displaying the relative ratio between the total amount of tool pass frequency and the total amount of residual frequencies changing chronologically. System for monitoring the processing status of a working machine claim 11 , characterized in that in the changes display window, a prediction threshold value for judging that a prediction state for quality judgment has come, and at least one of an upper threshold value and a lower threshold value by which the occurrence of a processing abnormality is differentiated are set. System for monitoring the processing status of a working machine claim 11 , characterized by a total power display window in which a total power of the vibrations changing with the machining is displayed, a frequency spectrum display window in which the frequency spectrum obtained by Fourier transformation of the machining vibrations is displayed, a LPF vibration display window in which the tool pass frequency is displayed in the frequency spectrum, and a NON-TPF vibration display window in which the residual frequencies are displayed in the frequency spectrum. System for monitoring the processing status of a working machine claim 9 or 10 characterized by a multicolored change display window displaying a first section displaying the total amount of tool pass frequency and a second section displaying the total amount of residual frequencies by different colors or different color depths changing chronologically.

Images