JPS59166451A - Monitoring device for cutting condition of electric cutting machine - Google Patents

Abstract

PURPOSE:To enhance the accuracy of cutting, stability of work and efficiency of production, by converting the cutting motive power of an electric motor into an electric quantity and comparing it with a normal value to monitor the condition of cutting and whether a cutting tool is worn out or damaged. CONSTITUTION:When a measurement starting push button 10 is pressed and the average of ten cutting electric power values is established, a stand-by instruction is removed and every cutting electric power value from a limit circuit 27 is compared with the average by a circuit 31 for judgment. The result of the judgement is indicated as ''no cutting'' 17, ''light cutting'' 18 or ''heavy cutting'' 20 so that an electric motor can be immediately stopped through a motive power stop circuit 32 and a warning indicator 21. A workpiece normally cut is indicated at every cutting by a normal cutting indicator 19. The number of normal cuttings is calculated by an indication counter 23 for control. Since the electric power value fluctuates due to the wear of a tap or the fluctuation of a power source or the like, the running average is determined to detect the wear of the tap or the like. The condition of cutting is thus monitored with high reliability to stabilize the cutting.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cutting state monitoring device for an electric cutting machine such as an automated electric screw cutting machine.

Recently, the use of robots has become commonplace in mass production factories such as automobile production factories. For example, robots are used to perform most tasks such as welding screws to car bodies and screwing screws into female threads. For this reason, if there is even one defective part or defective product in the female thread or the screw mated to the female thread, the production process will be disrupted and the production rate will drop significantly, so it is common to use robots. As the automation of electric cutting machines progresses, the cutting precision of internal threads or drilled holes will be required to be higher and higher.

Conventional methods for monitoring the cutting accuracy of female threads, for example, have been to measure by screwing a specified limit gauge onto the female thread and sorting out good and defective products, but this method requires a considerable amount of time to measure and Since measurement cannot be performed until the female thread has been cut, there are disadvantages in that production efficiency is reduced and manufacturing costs are increased. In addition, measuring the wear of cutting tools (tap) for internal threads requires a separate measuring device and measuring process, which has the disadvantage of lowering work efficiency and increasing manufacturing and reporting costs. Ta.

This invention was made in an attempt to eliminate such drawbacks.
The amount of power required for each cutting by the electric motor, which is the driving source for dynamic cutting A, is converted into an electrical quantity by a power converting means and a central processing means connected to the power converting means, and is digitized, and this electrical quantity is used for normal cutting. The present invention is characterized in that it is possible to accurately verify and monitor whether the cutting condition is good or bad by comparing the amount of electricity at the time, and to detect and monitor wear and tear of the cutting tool.

1 to 6 show one embodiment of the present invention, in which FIG. 1 is a circuit diagram of the entire cutting condition monitoring device, FIG. 2 is a circuit diagram of the central processing means and peripheral equipment, and FIG. Figure 4 is a diagram showing the power waveform for each cutting of the power conversion means, Figure 4 is a diagram showing the verification value of the cutting power value, Figure 5 is a diagram showing the estimation of the moving average value,
FIG. 6 is a diagram showing a specific example of testing whether the cutting part is good or bad.

In the figure, (1) is the electric motor that is the drive source of the electric cutting machine, and (2) is the electric power connected to this electric motor (1) via current transformers (3), (4), and transformer (5). With the conversion means,
For example, when cutting a female thread with a tap connected to an electric cutting machine, the required power of the electric motor (1) for each cutting is converted into an electric quantity. (6) is an electromagnetic switch connected to the power circuit,
If an abnormality occurs during machining of a female thread, it is activated immediately to stop the electric motor (1). (7) is power conversion means (2)
central processing means (hereinafter referred to as CPL),
(8) is a cam mechanism for synchronizing signal when cutting female threads, (9)
is connected to this cam mechanism (8) and CPL (7
) detects the signal from the cam mechanism (8) and sends it to the CPL (7). (10 is the push button for measurement start, 0]) is the push button for stop reset, (2) is the push button for start reset, 01 is the digital switch for numerical value setting, αY, Qo, αQ are the digital switches 03 for numerical value setting. When the setting value insertion switch is 041α, 91. Digital switch OJ for numerical value setting and push buttons (10, (11), (a) are C
Connected to PL (7). Gη~(a) is a means of displaying the verification results of the required cutting power when cutting female threads. Depending on the required power, no cutting, Qp, light cutting (g), and normal cutting (
11.Displayed in four stages: heavy cutting (e). Qp
(a) is a warning display when cutting female threads, (a) is an electric motor (
1) The stop relay is a counter that displays the number of normal female threads cut. (c), relay (a) and display means 0η to Q]) are connected to CPL (7). Next, the CPL (7) and the peripheral equipment of this CPL (7) will be explained according to FIG. (7
) is a CPL, and (c) is a conversion circuit provided in this CPL (7), which receives an analog signal from the power conversion means (2) and digitizes it. (b) is CPL (7)
This is a synchronization circuit provided for each female thread cutting, and is connected to the synchronization proximity switch (9) and the 1 conversion circuit (c).

(E) is an addition/subtraction circuit provided in the CPL (7), which is connected to the synchronization circuit (2) and the 1 conversion circuit (C), and receives the signal from the power conversion means (2) to calculate the digital amount every time the female thread cutting is completed. At the same time, the no-load equivalent amount set by the digital switch (To) is subtracted from the added value. (B)
The limiting circuit provided in the CPL (7) limits the maximum and minimum ranges of the female thread diameter in the cutting state. )
is an average value calculation circuit provided in the CPL (7), which calculates the average value of the female thread cutting amount each time.

翰 is a circuit that prohibits changing the limit range in the limit circuit (A) for setting the interval time of average value calculation and for cold start such as when starting work, which is provided in CPL (7), and (7) is C
A numerical value conversion circuit (01) is provided in the CPL (7) and distributes the numerical value of the digital switch α according to the selection of the set value insertion switches 0Φ to Ofj, and the average value settlement circuit (01) is provided in the CPL (7). Ratio ・11 (!) to verify the amount of electricity for cutting each time from the control circuit based on the average value output from the
, light cutting (2), normal cutting 0, and heavy cutting (1), and in the case of no cutting, light cutting 0, and heavy cutting, the electric motor (1) is passed through the power stop circuit (A). ) to stop. (To) is a cutting tool warning detection circuit installed in CPL (7).Since the average cutting amount is approximately proportional to the amount of wear on the cutting tool (tap), it is detected by the detection circuit □□□. The value detected by the detection circuit (to) is compared with the limit value of the female thread cutting value set by digital switch a3, and when the value detected by the detection circuit (to) reaches the limit value, the relay (support) is activated and the electric motor (1) is activated. stops.

In a device configured in this way, for example, a case where a weld nut is cut will be explained.

Electric motor for cutting female threads with taps in each drill hole (1)
The power required for each cutting is converted into an electrical quantity by the power conversion means (2), and the analog signal sent from the power conversion means (2) is digitized by the 1 conversion circuit (c) of the CPL (7). Four arithmetic operations on electrical quantities are possible, and waveform verification of analog quantities is also possible with high precision.

That is, the power waveform for each cutting of the female thread becomes a chevron-shaped waveform as shown in FIG. 3 due to the response delay of the power conversion means (2) in the transformer (5). Only the important part of this waveform for verification of the medium cutting state is synchronized and verified via a synchronization proximity switch (9) to a synchronization circuit for each female thread cutting. That is, the range of one-point confusion in FIG. 8 is the synchronization range of one waveform. This synchronization range portion is converted into a digital amount by the ~Φ conversion circuit (c), and furthermore, all portions corresponding to the waveform area are added together by the addition/subtraction circuit (a). ? fliJ machine (1)
The machine rotates all the time and consumes a considerable amount of power for operations other than cutting.

In other words, this power is equivalent to no-load power. Electric motor (1)
The accuracy of the verification is improved by subtracting this no-load equivalent power from the required power. The value to be subtracted from the power equivalent to no-load through the numerical conversion circuit (to) is set by the combination of the digital switch for numerical setting (to) and the switch for setting value insertion α4, and then the subtraction is performed by the addition/subtraction circuit. It will be done. The state is shown in FIGS. 3 and 4. That is, the fourth
In the figure, the digital value of the amount of cutting electricity (hereinafter referred to as cutting power value) rises in a triangular wave shape. Furthermore, the signal output from the addition/subtraction circuit (A) is roughly checked in the limit range set by the combination of the digital switch α 葅 for numerical value setting and the switch αυ for setting value insertion in the limiting circuit, and then the comparison test circuit C1■
to go into. On the other hand, the cutting power value from the limiting circuit (goods) is added and divided at regular intervals in the average value calculation circuit (c) so that, for example, the average value for cutting 10 female threads is calculated. . In this state, push button Ql to start measurement)
When is pressed, a standby command is first issued to the comparison verification circuit 0υ from the prohibition circuit (2) to the limit circuit until the average value of 10 cutting power values is obtained. When the average value of the 10 cutting power values is established, the standby command is removed and the comparison test circuit η performs a comparison test between each cutting power value and the average value from the limiting circuit (support). Figure 6 is a diagram showing a specific example of this test, in which the shaded area indicates normal cutting products, and the rest are abnormal products.
, is displayed as heavy cutting (a), and the electric motor (1) is immediately stopped via the power stop circuit) and the warning display means 2+). Normally cut items are displayed each time they are cut by the normal cutting display means Q. Calculation management is performed using a display counter for the number of normally cut items. Note that if there is wear on the tap or fluctuations in the surrounding conditions such as the power supply, the cutting power value of normally cut products will vary significantly. Therefore, calculation of the average value requires repeating measurements at short time intervals. That is, it is necessary to measure the moving average value. Once the average value is measured, the previous average value is used for verification during the next measurement, so waiting for calculation of the average value is only required for the first time. A stable power source is used as the motive power source, and when the fluctuation of the moving average value due to the power source is removed, the remaining factors are mainly tap wear and the like. In other words, the moving average value indicates the degree of tap wear. FIG. 5 is a diagram showing the transition of the moving average value corresponding to the number of female threads to be cut. The limit value is determined by the combination of the tap and the workpiece, and when the limit value is exceeded, a warning display is displayed. The comparison test results output from the moving average value, limit W value, and comparison test circuit (b) are compared to the electric motor (
1) A warning is issued by the display means of the stop relay (a). The limit value is determined in advance by collecting data, and is set in the comparison verification circuit (c) via the numerical conversion circuit (to) in combination with the display counter for the number of normal cutting pieces and the set value insertion switch OQ. be done. For example, when the MYib machine (1) temporarily stops during heavy cutting (E), the stop reset push button αυ is pressed, and the heavy cutting display means lights up to clearly indicate the cause of the stoppage until the stop reset button is pressed. Also,
morning's! ? During operation, the load acting on the electric tQj 74 (1) becomes heavy due to the influence of cutting oil, lubricating grease on rotating parts, etc. In such cases, press the start reset push button (2) and perform further measurements. By pressing the start button 0, the limit range of the time limit circuit (a) is slightly changed. After this time has elapsed, the normal state will be automatically restored.

Although this embodiment uses the power conversion means (2), it is also possible to use a current conversion means, although the monitoring accuracy decreases, and when using the current conversion means, a transformer ( 5) is of course unnecessary.

Further, in this embodiment, a tap is connected to a cutting tool of an electric cutting machine to cut a female thread, but the invention is not limited to this embodiment. Of course, it may also be used as a monitoring device when drilling or cutting work is performed by combining the above-mentioned devices.

As explained above, the present invention includes an electric motor that serves as a drive source for an electric cutting machine, a power conversion means connected to this electric motor and converting the required power of the electric motor for each cutting into an electrical amount, and a power conversion means connected to this conversion means. a central processing means for calculating and comparing and verifying the required amount of electricity sent from the converting means; a display means connected to the processing means for displaying the verification results of the processing means and the number of normally cut pieces; Since the configuration is equipped with a stopping means for stopping the connected electric motor and an automatic return means for the electric motor, the accuracy of cutting the workpiece by the electric scraper is significantly improved, and the cutting condition can be quickly and accurately determined. Since it is possible to carry out accurate verification monitoring and also detect and monitor wear and tear on the cutting tool, it is possible to provide a cutting state monitoring device for an electric cutting machine that significantly stabilizes and improves cutting workability and is reliable. For this reason,
When a robot or an automated electric cutting machine is introduced for mass production work, the synergistic effect with the above can significantly improve production efficiency and significantly reduce the production price.

[Brief explanation of drawings]

Figures 1 to 6 show one embodiment of the present invention. Figure 1 is a circuit diagram of the entire cutting state viewing device, Figure 2 is a circuit diagram of the central processing means and peripheral equipment, and Figure 6 is a circuit diagram of the entire cutting state viewing device. Fig. 3 is a diagram showing the power waveform of the power conversion means for each cutting, Fig. 4 is a diagram showing the verification value of the cutting 1111 power value, Fig. 5 is a diagram showing the transition of the moving average value, and Fig. 6 is a diagram showing the cutting part. 2 is a diagram illustrating a specific example of the inspection of good or bad quality. In the diagram, (1) is an electric motor that is the drive source of an electric cutting machine, (2) is a power conversion means, and (3) and (4) are current transformers. ,
(5) is a transformer, (6) is an electromagnetic switch, (7) is a central processing means, (8) is a force 11 mechanism for synchronizing signals, (9)
is a proximity switch for synchronization, Oq is a push button for starting measurement, Ql)
is a push button for stop reset, (2) is a push button for start reset,
(To) is a digital switch for numerical value setting, α Cal (E)
is a display means, (a) is a relay, (a) is a counter for displaying the number of normal cutting pieces, (c) is an N-conversion circuit, (c) is a synchronization circuit, (a) is an addition/subtraction circuit, and (a) is a limiting circuit. (c) is an average value calculation circuit, slope is an inhibition circuit, (to) is a numerical conversion circuit, e is a ratio axis verification circuit, 翰 is a power stop circuit, and (a) is a comparison verification circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno - Commissioner of the Japan Patent Office 1. Indication of the case: Japanese Patent Application No. 58-41264 2, Name of the invention: Cutting condition monitoring device for electric cutting machine 3, Representative Hitoshi Katayama of the person making the amendment: 5, Drawings to be amended 6, Contents of the amendment (1) Drawings shall be corrected as shown in the attached sheet. 7. List of attached documents (1) Drawings (Figure 1) 1 or more copies

Claims (5)

[Claims] (1) An electric motor that is the drive source of an electric cutting machine, an electric quantity converting means connected to this electric motor and converting the required power of the electric motor for each cutting into an electric quantity, and an electric quantity converting means connected to this converting means and converted from the converting means central processing means for calculating and comparing and verifying the required amount of electricity to be sent; a display means connected to the processing means for displaying the verification results of the processing means and the number of normal cutting pieces; and a display means connected to the processing means A cutting state monitoring device for an electric cutting machine, comprising a stopping means for stopping the electric motor and an automatic return means for the electric motor. (2) The central processing means includes an N-conversion circuit, a synchronization circuit for each cutting of the cutting section, an addition/subtraction circuit, a limiting circuit, an average value calculation circuit, an inhibition circuit, a numerical conversion circuit, and a first 2. The cutting state monitoring device for an electric cutting machine according to claim 1, comprising a comparison verification circuit, a second comparison verification circuit, and a power stop circuit. (3) The display means for displaying the test results is a lighting means, and the cutting status of the 1π dynamic cutting machine according to claim 1 is characterized in that the display means displays normal, no cutting, light cutting, and heavy cutting, respectively. Monitoring equipment. (4) The cutting state monitoring device for an electric cutting machine according to claim 1, wherein the stopping means is a relay. (5) The cutting state monitoring device for an electric cutting machine according to claim 1, wherein the automatic return means includes a measurement start push button, a stop reset push button, and a start reset push button.