JPH06226452A - Device and method for detecting service life of plasma electrode - Google Patents

Abstract

PURPOSE:To detect the service life of an electrode in the plasma torch of a plasma automatic machine. CONSTITUTION:In a plasma automatic machine 10 where the plasma arc torch 1 is mounted and machining by it is performed based on the sequence preset by programming or teaching, the electrode tip central position in the arc torch is measured by an electrode tip position measuring unit 50 arranged on the plasma automatic machine or outside the automatic machine. The electrode tip central part position when the electrode is new is measured to store its value, besides, the electrode tip central part position is measured at every number of the times in machining which is compared and calculated with the measured value of the electrode tip central part position when the electrode is new and when this compared value is higher than a service life judging value, a warning means for notifying the service life is taken.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma electrode life detecting device and method, and more particularly, to the life of electrodes in a plasma torch of an automatic plasma processing machine equipped with a plasma torch on an NC table, a robot or the like. It is about detecting.

[0002]

2. Description of the Related Art Normally, the service life of the electrodes of a plasma arc torch for welding, cutting, etc. using a plasma arc gradually increases as the time of use increases, and the wear of the plasma arc torch progresses in the depth direction. When the wear depth reaches a specified value, the heat input from the plasma arc to the electrode becomes excessive and heat damage occurs, making it unusable, or the plasma arc becomes unstable and a double arc occurs. Then the electrode is disabled. In particular, when oxygen or air is used as a working gas for high-speed cutting of mild steel or the like, the electrode wear rate is extremely high and the electrode cannot be used in a short time. When the electrode is damaged, other parts of the torch such as the nozzle are damaged, and the work piece becomes defective, so that post-processing such as replacement of the damaged piece requires a lot of man-hours, resulting in a large amount of waste. For this reason, the operator determines, based on experience, when the electrode is likely to be damaged, and replaces the electrode early, or frequently monitors the electrode to find damage to the electrode early. Therefore, since it is necessary to lighten the burden on the operator, the following method for detecting the life of the electrode of the plasma torch has been proposed. (1) When the electrode is damaged due to the occurrence of double arc,
A change in current or voltage between the electrode and the work piece, between the electrode and the nozzle, or between the nozzle and the work piece is detected. (JP-A-6
2-24864) (2) Detecting increase / decrease and fluctuation of voltage between the nozzle and the electrode during processing. (Japanese Patent Laid-Open No. 62-127173) (3) Detect an increase in voltage between the nozzle and the electrode during main arc generation. (Japanese Patent Publication No. 4-6437) (4) The electrode wear amount is estimated from the number of times of machining, the machining current, and the machining time based on a constant arithmetic expression, and the estimated wear amount and the allowable wear amount are compared to generate an alarm, Stop work or display remaining life. (JP-A 2-6070)

[0003]

However, in the above-mentioned conventional methods, (1) JP-A-62-24864 and (2) JP-A-62-127173,
It can be detected only when the electrode is damaged by the generation of double arc. In Japanese Patent Publication No. 4-6437 of (3), the rate of voltage change is too small and the detection error is large, and it is determined that the life is long before the end of life, or the electrode is damaged before the life is determined. There is a problem that it will end up. Further, in (4) Japanese Patent Application Laid-Open No. 2-6070, the consumption amount of the electrode is estimated from the values of the number of times of machining, the machining current, and the machining time. There is a difference between the consumption amount and the problem that the life is judged to be long before the life, or the electrode is damaged before the life is judged. As described above, each proposal has been made, but in reality, a method for actually detecting the life of the electrode of the plasma torch has not been presented yet.

The present invention focuses on the above-mentioned conventional problems and relates to a life detecting device and a detecting method for a plasma electrode, and in particular, an electrode of a plasma torch of an automatic plasma processing machine in which a plasma torch is mounted on an NC table, a robot or the like. The purpose of the present invention is to reliably detect the service life of a battery with a simple structure before the electrode is damaged.

[0005]

In order to achieve the above object, in the first aspect of the present invention, a plasma arc torch is mounted, and a plasma arc torch is used based on a sequence set by programming or teaching in advance. In the automatic plasma processing machine that performs processing,
Measuring means for measuring the central position of the electrode tip inside the plasma arc torch on and off the automatic plasma processing machine, and the central position of the electrode tip when the electrode is new and store the measured value A storage means, a comparison calculation means for measuring the center position of the electrode tip for each machining number, storing the measured value, and performing a comparison calculation with the measurement value of the center position of the electrode tip when the product is new, and the comparison value is the life. It comprises a comparison / determination means for comparing and judging whether or not it is larger than a judgment value, and a warning means for notifying the life when it is larger than the life judgment value.

According to a second aspect of the present invention, a plasma arc torch is mounted, and the processing by the plasma arc torch is performed based on a sequence set by programming or teaching in advance. The position of the center of the electrode tip inside the arc torch is measured by the measuring means installed outside the automatic processing machine, the position of the center of the electrode tip when the electrode is new is measured, and that value is stored, and The center position of the electrode tip is measured for each time, and the calculated value is compared with the measured value of the center position of the electrode tip at the time of new product. When this comparison value is larger than the life judgment value, the life is notified.

[0007]

According to the above construction, the size of the electrode of the plasma torch before use is measured and stored, and the size of the electrode of the plasma torch is measured after a predetermined number of uses.
By comparing this size with the size before use, the electrode wear of the plasma torch can be surely grasped, the progress of this wear is memorized, and the life of the electrode is measured by measuring the number of times of the predetermined number of times frequently. It can be reliably detected before it is damaged. As a result, it is possible to prevent damage to the nozzle and defects in the workpiece, and it is possible to make the processing unmanned.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plasma electrode life detecting device and a detecting method according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a first embodiment of a plasma electrode life detecting device according to the present invention. In FIG. 1, a plasma automatic processing machine 10 equipped with a plasma arc torch 1 has a pedestal 3 on which a workpiece 20 is mounted and fixed.
It is arranged near 0. The plasma arc torch 1 is connected to a plasma power source 40 and also to a working gas supply device (not shown) such as oxygen or air. An electrode tip position measuring unit 50 is arranged near the automatic plasma processing machine 10 and the gantry 30. In the electrode tip position measurement unit 50, a measurement device 56 is arranged on a measurement stand 52 via a measurement control device 54. The automatic plasma processing machine 10 and the measurement control device 54 are connected to an automatic processing machine control device 60. The plasma automatic processing machine 10 comprises a robot processing apparatus 11 having a normal multi-joint operating mechanism, and within the operation range of the plasma automatic processing machine 10 according to a sequence preset by programming or teaching from the automatic processing machine control device 60. The workpiece 20 on the pedestal 30 arranged in the above is processed.

Next, FIG. 2 is a block diagram of a control circuit of a plasma electrode life detecting device. In FIG. 2, a robot processing apparatus 11 equipped with a plasma arc torch 1
The automatic processing machine control device 60 is connected to the automatic processing machine control device 60, and the automatic processing machine control device 60 is programmed in advance by programming or teaching and the controller 62 and programming or teaching is input, or the plasma electrode of the plasma electrode is set every predetermined number of times of processing. A keyboard 64 for inputting a command for measuring the life is connected. The plasma arc torch 1 is composed of a plasma electrode 3 and a nozzle 5 as in the existing case. An electrode tip position measuring unit 50 is arranged at a predetermined position on the tip of the plasma arc torch 1, and the electrode tip position measuring unit 50 is composed of at least a measuring device 56 and a measurement control device 54. There is. The measurement control device 54 outputs a measurement command to the electrode tip position measurement unit 50 when the plasma arc torch 1 reaches a predetermined position before processing according to a command from the automatic processing machine control device 60, and a controller 54a. The storage device 54b that stores the measured value and the limit wear amount of the electrode, and the controller 54a that outputs the measurement command of the wear amount of the plasma electrode to the electrode tip position measuring unit 50 at every predetermined number of times of machining, together with the wear amount of the plasma electrode are stored. In addition, the comparison calculation device 54c for performing a comparison calculation with the limit consumption amount and the comparison determination unit 54d for determining the comparison between the limit consumption amount and the measured value and determining whether or not this comparison value is larger than the life determination value. And a warning output device 58 that outputs a warning to the operator when the limit consumption amount is exceeded. In the above configuration, the keyboard 64 for inputting a command for measuring the life of the plasma electrode to the automatic processing machine control device 60 every predetermined number of times of processing.
, But may be connected to the controller 54a that outputs a measurement command to the electrode tip position measurement unit 50. The electrode tip position measurement unit 50 includes a sensor 59 for detecting that the plasma arc torch 1 has reached a predetermined position of the electrode tip position measurement unit 50, and a measurement control device 5.
The controller 54a of No. 4 receives a signal from the sensor 59 to operate the electrode tip position measuring unit 50 to measure the amount of wear of the electrode and to output a measurement signal.

In the above structure, the operation will be described with reference to FIG.
This will be described with reference to the flowchart of FIG. In FIG.
When the plasma arc torch 1 is changed or replaced by a new one, the robot processing device 11 is operated by the automatic processing machine control device 60 by a command from the keyboard 64, and the plasma arc torch 1 is moved to a predetermined position of the electrode tip position measuring unit 50. Move to the position. When the sensor 59 detects that the plasma arc torch 1 has reached a predetermined position of the electrode tip position measurement unit 50, the measurement control device 54
Of the electrode tip position measuring unit 50 by the controller 54a of
4, the measuring device 56 measures the initial position (h0) of the tip 3a of the new electrode from the hole 5a of the nozzle 5 and stores the measured value (h0) in the storage device 54b. .

Next, the robot processing apparatus 11 is operated by the automatic processing machine control device 60 to process (T) the workpiece 20 a predetermined number of times. After machining a predetermined number of times by programming or teaching, the robot machining device 11 is operated by the automatic machining machine control device 60 to move the plasma arc torch 1 to a predetermined position of the electrode tip position measuring unit 50. When the sensor 59 detects that the plasma arc torch 1 has reached a predetermined position of the electrode tip position measurement unit 50, the controller 54a of the measurement control device 54 activates the electrode tip position measurement unit 50, and the measurement device 56 causes the electrode tip position measurement unit 50 to operate. As shown in FIG. 3, the electrode wear amount position (hi) after machining a predetermined number of times is measured. Next, the measured value (h0) of the center position of the electrode tip at the time of new product is compared with the consumed amount position (hi) of the electrode after machining a predetermined number of times (Wi = hi-h0), and the result is stored in the storage device 54b. The measured values for each number of times are stored as shown in FIG. 6 and the number of times of processing and the accumulated electrode consumption amount (Wi) are stored. At this time, the comparison value (Wi) is the life judgment value (WR
), That is, the wear amount (Wi) of the electrode approaches a predetermined value and the operator is informed that the life has come to the warning output device 58.

Next, the result of confirming the consumption rate of the electrodes using the apparatus of the present invention will be described with reference to FIG. In FIG. 7, using the same current value of 90 A, the same plate thickness of 9 mm was cut, and the relationship between the electrode consumption amount mm and the number of times of machining was investigated. In this investigation, the time (t) from the start to the end of arc generation was changed, a workpiece having a similar shape was processed, and the amount of electrode wear and the number of electrode breakages were measured. In line (a),
As a result of setting t = 6 sec, the plasma arc torch was damaged when the number of machining was about 800 and the electrode consumption amount was 1.8 mm. In the line (b), as a result of setting t = 60 sec, the plasma arc torch was broken at the electrode wear amount of 1.75 mm after about 270 machining cycles. In line (c), t = 300s
As a result of ec, the plasma arc torch was damaged at the electrode wear amount of 1.85 mm after the processing was performed about 200 times. From the above results, the electrode wears out if the time (t) from the start to the end of arc generation is different, or other conditions (gas flow rate, cooling water temperature, etc.) are different, even if the current value is the same. The speed is changing. Even with the same electrode, the consumption rate of the electrode changes depending on the structure of the electrode material and the like. Therefore, the life of the electrode was predicted by the conventional change in voltage and current, but it was actually difficult to judge. However, depending on the consumption depth (amount) of the electrode of the present invention, it has been found that the life of the electrode can be detected without variation even if these conditions are different, at the same consumption depth (amount) of the electrode.

FIG. 8 is a schematic configuration diagram of a second embodiment of the plasma electrode life detecting device according to the present invention. In FIG. 8, the NC gantry automatic processing machine 110 includes a gate pole 120 that moves in the X-axis direction along a mount 130 on which the plasma arc torch 1 is mounted, and a plasma arc torch 1 that is arranged in the gate pole 120 and moves the plasma arc torch 1 in the Y-axis direction. Y-axis direction slider 125 and Z-axis direction slider 1 arranged on the slider 125 for moving the plasma arc torch 1 in the Z-axis direction
27, and a mount 130 for mounting and fixing the work piece 20,
It consists of The plasma arc torch 1 is connected to a plasma power source 40 and also to a working gas supply device (not shown) such as oxygen or air. In addition, the NC gantry automatic processing machine 110 and the pedestal 130
An electrode tip position measuring unit 150 is arranged near the. The electrode tip position measuring unit 150 is arranged together with the measurement control device 154 on the measurement stand 152,
Further, the measuring gantry 152 has a measuring gantry arm 152a, is configured to swing at an angle of 90 degrees, and the measuring device 56 is disposed at the tip thereof. Also, NC
Gantry automatic processing machine 110 and measurement control device 154
Is connected to the automatic processing machine control device 60. NC
Gantry automatic processing machine 110, X-axis direction, Y-axis direction,
Alternatively, the movement in the Z-axis direction is performed by programming in advance from the automatic processing machine control device 60 or by a sequence set by teaching, and the workpiece to be processed on the gantry 130 arranged within the operation range of the NC gantry automatic processing machine 110 is processed. The object 20 is processed.

Next, in the block diagram of the control circuit of the apparatus for detecting the life of the plasma electrode, the configuration is almost the same as that of the first embodiment, but as described above, it swings to the electrode tip position measuring unit 150. When the measurement pedestal arm 152a is provided and the life of the plasma electrode is detected, the measurement pedestal arm 152a rotates in the direction above the pedestal 130 to a predetermined position within the operating range of the plasma arc torch 1,
The electrode comes to a position where the initial position of the electrode can be measured or the consumption depth (amount) after machining a predetermined number of times can be measured.

Next, the operation of the above structure will be described. Similar to the first embodiment, when the plasma arc torch 1 is changed or replaced by a new one, the measurement pedestal arm 152a is rotated to a predetermined position above the pedestal 130 by a command from the keyboard 64. Next, the NC gantry automatic processing machine 11 is controlled by the automatic processing machine control device 60.
The plasma arc torch 1 of 0 is moved in the X-axis direction, the Y-axis direction, or the Z-axis direction, and the plasma arc torch 1 is moved to a predetermined position of the electrode tip position measuring unit 150. When the sensor 59 detects that the plasma arc torch 1 has reached the predetermined position of the electrode tip position measurement unit 150, the controller 54a of the measurement control device 54 activates the electrode tip position measurement unit 50 and the measurement device 56.
Thus, as shown in FIG. 4, the initial position of the new electrode is measured and the measured value is stored in the storage device 54b. Next, the automatic processing machine control device 60 operates the plasma arc torch 1 of the NC gantry automatic processing machine 110 in the X-axis direction, the Y-axis direction, or the Z-axis direction to process the workpiece 20 a predetermined number of times. After machining a predetermined number of times by programming or teaching, mount the measurement stand arm 152a to the stand 1
Rotate in the direction above 30 to a predetermined position. Further, the NC gantry automatic processing machine 11 is controlled by the automatic processing machine control device 60.
The plasma arc torch 1 of 0 is operated in the X-axis direction, the Y-axis direction, or the Z-axis direction to move the plasma arc torch 1 to a predetermined position of the electrode tip position measuring unit 50. When the sensor 59 detects that the plasma arc torch 1 has reached a predetermined position of the electrode tip position measurement unit 50, the controller 54 a of the measurement control device 54 activates the electrode tip position measurement unit 150, and the measurement device 56 causes the measurement result of FIG. As shown in FIG. 6, the electrode wear amount position after machining a predetermined number of times is measured, and the measured value for each predetermined number of times is stored in the storage device 54b as shown in FIG. In the above embodiment, the sensor 59 detects that the electrode tip position measuring unit 50 has reached a predetermined position, but it may be set in advance by a program so as to come to a predetermined position. Further, when the plasma arc torch 1 reaches the electrode tip position measuring unit 50, it may enter the hole of the plasma arc torch 1 and automatically measure the position of the electrode tip. further,
Although the NC gantry automatic processing machine 110 has been described, a gate type automatic processing machine may be used.

[0016]

As described above, according to the present invention,
By measuring and storing the dimensions of the electrode of the plasma torch before use, and by measuring the dimensions of the electrode of the plasma torch after a certain number of times of use, and comparing this dimension with the dimensions before use, the plasma torch can be reliably measured. The consumption of the electrode can be grasped, and the progress of the consumption is stored, so that the life of the electrode can be surely detected before it is damaged by passing a predetermined number of times of measurement. This will prevent damage to the nozzle and defects in the workpiece,
Moreover, unmanned processing can be performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a plasma electrode life detecting device according to the present invention.

FIG. 2 is a block diagram of a control circuit of a plasma electrode life detecting device according to the present invention.

FIG. 3 is a flow chart diagram according to the present invention.

FIG. 4 is a diagram for measuring an initial position of a new electrode.

FIG. 5 is a diagram for measuring the wear amount position of the electrode after processing a predetermined number of times.

FIG. 6 is a diagram showing measured values for each predetermined number of times.

FIG. 7 is a diagram showing the results of confirming the amount of electrode wear and the number of damages of the plasma arc torch 1 using the device of the present invention.

FIG. 8 is a schematic configuration diagram of a second embodiment of a plasma electrode life detecting device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Plasma arc torch 54c Comparison calculation device 3 Plasma electrode 54d Comparison judgment means 5 Nozzle 56 Measuring device 10 Plasma automatic processing machine 58 Warning output device 11 Robot processing device 60 Automatic processing machine control device 20 Workpiece 62 Controller 30 Stand 64 Keyboard 40 Plasma power source 50 Electrode tip position measurement unit 54 Measurement control device 54a Controller 54b Storage device

Claims (2)

[Claims] 1. A plasma automatic processing machine equipped with a plasma arc torch and performing processing by the plasma arc torch based on a sequence preset by programming or teaching, on a plasma automatic processing machine or on or outside the automatic processing machine. The measuring means for measuring the central position of the electrode tip in the plasma arc torch, the measuring means for measuring the central position of the electrode tip when the electrode is new and storing the measured value, the electrode tip center for each machining Comparing calculation means that measures the position of the part, stores the measured value, and compares it with the measured value of the center position of the electrode tip at the time of new product, and compares this comparison value with the life judgment value. The life of the plasma electrode is characterized by comprising a comparison judgment means for judging and a warning means for notifying the life when the life judgment value is larger than the life judgment value. Life detection device. 2. A plasma automatic processing machine equipped with a plasma arc torch and performing processing based on a sequence set in advance by programming or teaching, in a plasma automatic processing machine or outside the automatic processing machine. Measure the center position of the electrode tip inside the arc torch with the measuring means provided, measure the center position of the electrode tip when the electrode is new, and store the value, and the center position of the electrode tip for each machining count. A method of detecting the life of a plasma electrode, characterized in that the life of the plasma electrode is notified when the measured value is compared with the measured value of the center position of the electrode tip when the product is new, and the comparison value is larger than the life judgment value.