JP2014054650A - Protection control method of welding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which production efficiency decreases since welding is forcibly stopped to prevent burning when the temperature rise of a welding torch reaches a reference value.SOLUTION: In the protection control method of a welding device for arc-welding using a water-cooling welding torch, temperature of condensed water flowing out from the welding torch is detected by a temperature sensor, and when a temperature detection value Hd of the temperature sensor reaches a temperature reference value Ht, energization of a welding current Iw is blocked. When it is estimated that the temperature detection value Hd will reach the temperature reference value Ht after predetermined time Td, an alarm Ar (High level) by a sound or the like is emitted. Since a welding operator changes a welding condition in response to the alarm Ar, reduction in production efficiency as well as burning of the welding torch can be prevented.

Description

  According to the present invention, a temperature sensor detects the temperature of condensate flowing out from a water-cooled welding torch, and when the temperature detection value from the temperature sensor reaches a temperature reference value, the welding apparatus cuts off energization of the welding current. The present invention relates to a protection control method.

  There are water-cooled welding torches used for arc welding such as plasma welding, TIG welding, carbon dioxide arc welding, mag welding, and MIG welding. In this water-cooled welding torch, cooling fluid such as water (hereinafter referred to as cooling water) flows into the torch, circulates it, and then flows out to cool the torch body, the nozzle, and the like. The cooling water is often circulated by providing a cooling water circulator. In this case, the cooling water cooled by the cooling water circulator is sent to the welding torch, and the condensate warmed when circulating inside the welding torch is returned to the cooling water circulator.

  If the welding torch exceeds the temperature due to an excess of the usage rate, an increase in ambient temperature, an insufficient flow rate of the cooling water, etc., the welding torch may burn out and become unusable. In order to prevent such a state from occurring, the temperature of the condensate flowing out from the welding torch is detected by a temperature sensor, and when the temperature detection value from this temperature sensor reaches a predetermined temperature reference value, welding is performed. 2. Description of the Related Art Conventionally, a welding apparatus protection control method that interrupts current application has been performed (see, for example, Patent Document 1). By this protection control method, welding is forcibly stopped when the condensate temperature correlated with the temperature rise of the welding torch reaches a reference temperature at which the welding torch does not burn out, so that it is possible to prevent the welding torch from burning out. .

JP 2008-229644 A

  During the welding, if the above-described protection control of the prior art operates, the welding is forcibly stopped to protect the welding torch. The workpieces whose welding has been stopped in the middle are discarded or the welding is started again from the stop point. In either case, man-hours are required and production efficiency is reduced.

  Therefore, in the present invention, in arc welding using a water-cooled welding torch, there is provided a protection control method for a welding apparatus capable of preventing the welding torch from being burned out and suppressing a decrease in production efficiency. With the goal.

In order to solve the above-described problem, the invention of claim 1 is arc welding using a water-cooled welding torch, and the temperature sensor detects the temperature of condensate flowing out from the welding torch. In the protection control method of the welding apparatus for cutting off the energization of the welding current when the detected temperature value of the temperature reaches a predetermined temperature reference value,
When the temperature detection value is estimated to reach the temperature reference value after a predetermined time, an alarm is issued.
This is a protection control method for a welding apparatus.

According to a second aspect of the present invention, the estimation is performed based on a change rate of the temperature detection value.
The protection control method for a welding apparatus according to claim 1, wherein:

According to a third aspect of the present invention, the warning is performed by voice.
3. The protection control method for a welding apparatus according to claim 1, wherein the protection control method is used.

In the invention of claim 4, when the alarm is issued, the welding condition is automatically corrected so that the rate of increase in the temperature detection value is reduced.
It is a protection control method of the welding apparatus of any one of Claims 1-3 characterized by the above-mentioned.

  According to the present invention, when it is estimated that the temperature detection value from the temperature sensor that detects the condensate temperature from the welding torch reaches a predetermined temperature reference value after a predetermined time, “the temperature exceeds xx seconds later”. A warning by voice etc. is issued. Since the welding operator is warned before the temperature is exceeded, change the welding conditions while receiving the warning to prevent the temperature from exceeding the temperature even if the workpiece is welded to the end. Can do. Further, since the welding operator can stop the welding at a position where the welding can be easily resumed, the welding can be resumed smoothly after the welding power source is stopped. For this reason, the energization of the welding current is forcibly cut off due to excessive temperature, and the welding is not suddenly stopped. Therefore, it is possible to prevent the work from being discarded or taking a lot of man-hours when resuming welding. Therefore, after protecting the welding torch from burning caused by excess usage, etc. It can suppress that production efficiency falls.

It is a block diagram of the plasma welding apparatus for enforcing the protection control method which concerns on embodiment of this invention. It is a timing chart of each signal of Drawing 1 showing a protection control method concerning an embodiment of the invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the following description, a plasma welding apparatus that is particularly susceptible to burning of the welding torch is taken as an example. That is, in plasma welding, since the arc is constrained by the plasma nozzle to increase the energy density, if the cooling action of the welding torch decreases, there is a risk that the welding torch will soon burn out. Therefore, it is necessary to perform sufficient protection control.

  FIG. 1 is a configuration diagram of a plasma welding apparatus for carrying out a protection control method according to an embodiment of the present invention. Hereinafter, each component will be described with reference to FIG.

  The welding power source PS is a power source having a constant current characteristic or a drooping characteristic, the negative output is connected to the electrode 1, the positive output is connected to the base material 2, and the welding current Iw and the welding voltage Vw are output. A plasma arc 3 is generated between the electrode 1 and the base material 2. The welding power source PS receives an energization cut-off signal As and an alarm signal Ar from a protection controller HC, which will be described later, and stops the energization of the welding current Iw when the energization cut-off signal As changes to a high level. When the level changes to high level, an alarm such as turning on the abnormal indicator lamp is issued. Further, when the alarm signal Ar changes to the high level, the welding conditions such as the welding current Iw and the welding speed may be automatically corrected so that the rate of increase of the temperature detection signal Hd described later decreases. For example, when the alarm signal Ar changes to the high level, the set value of the welding current Iw is decreased at a predetermined rate (10% or the like), and this state is continued until the welding is completed.

  A welding torch WT surrounded by a broken line includes an electrode 1, a plasma nozzle 4 surrounding the electrode 1, and a shield nozzle 5 surrounding the electrode. The electrode 1 is a non-consumable electrode, and a tungsten electrode is often used. Plasma gas (not shown) flows through the plasma nozzle 4. A shield gas (not shown) flows through the shield nozzle 5. Argon gas is often used as the plasma gas and the shielding gas. The plasma arc 3 is restricted and narrowed by the plasma nozzle 4 and is generated between the electrode 1 and the base material 2. The plasma nozzle 4 is made of copper, and a flow path through which cooling water flows is provided inside.

  The cooling water circulator WC causes the water supply 61 to flow into the flow path of the plasma nozzle 4, cools the condensed water 62 flowing out from the flow path of the plasma nozzle 4 by the blower provided inside, and circulates it again as the water supply 61. The circulating cooling water 6 is classified into a water supply 61 and a condensate 62.

  The temperature sensor HD detects the temperature of the condensate 62 and outputs a temperature detection signal Hd (° C.). A thermistor or the like is used for the temperature sensor. The temperature sensor HD converts the thermistor resistance value change due to the temperature change into a temperature (° C.) and outputs it. In order to accurately detect the temperature rise of the welding torch, it is desirable to provide the temperature sensor near the welding torch body.

  Here, the principle of the protection control method according to the present embodiment will be described below. A temperature reference value Ht (° C.) for operating the temperature protection is set. This temperature reference value Ht is set to a value less than a value at which the welding torch does not burn out due to a temperature rise due to an excess of the usage rate. When the value of the temperature detection signal Hd from the temperature sensor reaches the temperature reference value Ht (Hd ≧ Ht), the welding current Iw is cut off and welding is stopped.

The temperature detection signal Hd from the temperature sensor is sampled at a predetermined sampling cycle Ts and detected as a digital value. The nth temperature detection digital value is Hdd (n). The duration time Td (seconds) is set in advance. An estimated value of the temperature detection signal Hd (hereinafter referred to as a temperature estimated value Hs (n)) at the time when the duration Td has elapsed from the present time (during the n-th sampling) is calculated by the following equation for each sampling period Ts. The This estimation is performed by calculating the temperature detection digital value Hdd (n) of the temperature sensor and its change rate ΔHd (° C./second).
Hs (n) = Hdd (n) + ΔHd · Td (1) where ΔHd = (Hdd (n) −Hdd (n−1)) / Ts. Alternatively, the change rate ΔHd may be calculated by obtaining a first-order recent equation from the past p pieces of data of Hdd (n)... Hdd (np).

  The sampling period Ts is set to about 0.1 to 5 seconds, for example. The duration Td is a constant for determining how many seconds from the present time it is estimated that the temperature will be exceeded, and is set to about 30 to 180 seconds, for example. According to the above equation, the estimated temperature value Hs is calculated for each sampling period Ts.

The protection controller HC receives the temperature detection signal Hd as described above, performs the following processing, outputs an energization cutoff signal As and an alarm signal Ar to the welding power source PS, and issues an alarm. The protection controller HC operates according to the principle of the protection control method according to the above-described embodiment.
Step 1: A sampling period Ts, a temperature reference value Ht, and a duration Td are set. Then, the temperature detection signal Hd from the temperature sensor is sampled and detected as a digital value at every sampling period Ts. The nth temperature detection digital value is defined as Hd (n).
Step 2: When the nth temperature detection digital value Hdd (n) reaches the temperature reference value Ht (Hdd (n) ≧ Ht), the energization cutoff signal As is changed to the High level and output. Thereby, energization of welding current Iw is interrupted and welding is stopped. On the other hand, when the temperature reference value Ht is not reached (Hdd (n) <Ht), the energization cutoff signal As remains at the low level and the energization of the welding current Iw is continued. When the energization cutoff signal As becomes High level, the process of Step 3 is not performed.
Step 3: The nth temperature estimated value Hs (n) is calculated for each sampling period Ts by the above equation (1), and the nth temperature estimated value Hs (n) reaches the temperature reference value Ht. When this occurs (Hs (n) ≧ Ht), the alarm signal Ar is changed to a high level and output, and an alarm is issued. The warning is given by a voice such as “The temperature will be exceeded in xx seconds later” so that the welding operator can recognize it while welding. Xx seconds are the above-described duration Td. Moreover, you may make it emit a warning by vibrating the grip part of a welding torch. It may be used in combination with lighting of the abnormality indicator lamp. Even if the alarm signal Ar changes to a high level, welding is continued only by issuing an alarm.

  FIG. 2 is a timing chart of each signal in FIG. 1 showing the protection control method according to the embodiment of the present invention. (A) shows the time change of the welding current Iw, (B) shows the time change of the temperature detection signal Hd from the temperature sensor, (C) shows the time change of the alarm signal Ar, FIG. 4D shows the time change of the energization cutoff signal As. This figure shows a case where the estimated temperature value Hs ≧ the temperature reference value Ht in Step 3 described above. Hereinafter, a description will be given with reference to FIG.

  As shown in FIG. 4A, the period from time t1 to t2 is a welding period in which the welding current I1 is energized, and the period from time t2 to t3 is a pause period in which the welding current Iw is not energized, from time t3 to t4. Is a welding period in which the welding current I1 is energized, the period from time t4 to t5 is a pause period, the period from time t5 to t6 is a welding period in which the welding current I2 is scheduled to be energized, and time t6 to t7 This period is a rest period. Here, I1 <I2. This embodiment is a case of non-consumable electrode arc welding, and since the welding power source is controlled at a constant current, the welding current value varies directly with the current setting value. On the other hand, in the case of consumable electrode arc welding, the welding current value varies depending on the feeding speed of the welding wire. Each welding period and each rest period have the same length of time. And the total value of a welding period and a rest period is 10 minutes which is a reference | standard period of a utilization rate.

  As shown in FIG. 5B, since the welding current I1 is energized at the same usage rate during the period before time t5, the value of the temperature detection signal Hd is as shown in FIG. It gradually increases during the welding period from time t1 to t2, gradually decreases during the suspension period from time t2 to t3, gradually increases during the welding period from time t3 to t4, and gradually decreases during the suspension period from time t4 to t5. To do. The maximum value of the temperature detection signal Hd before time t5 is at time t2 and t4. This maximum value is less than the temperature reference value Ht indicated by the alternate long and short dash line. The processes in steps 1 and 2 described above are performed, and the energization cutoff signal As remains at the low level as shown in FIG. In addition, during the period before time t5 after the processing of step 3 described above is performed, the estimated temperature value Hs calculated by the above equation (1) is in a state less than the temperature reference value Ht. For this reason, the alarm signal Ar is at a low level as shown in FIG.

  As shown in FIG. 5A, the welding current from time t5 increases from I1 to I2 because the welding current set value has changed. For this reason, as shown in FIG. 5B, the value of the temperature detection signal Hd rises from time t5 with a larger slope than at times t1 and t2. Then, at time t51 before time t6 when the welding ends, the value of the temperature detection signal Hd is in a state of less than the temperature reference value Ht. On the other hand, the process of step 3 described above is performed, and the estimated temperature value Hs calculated by the above equation (1) reaches the temperature reference value Ht at time t51 (Hd ≧ Ht). ), The alarm signal Ar changes to a high level for a short time, and a voice alarm is issued saying “the temperature will be exceeded in xx seconds later”. Here, xx seconds is the duration Td.

Upon receiving this warning, the welding operator determines whether or not the welding can be performed to the end in the duration time Td (seconds), and if possible, continues the welding without changing the welding conditions. When it is determined that it is not possible, for example, the following measures are taken in consideration of the welding quality.
1) The speed at which the welding torch is moved (welding speed) is increased so that welding can be performed to the end in less than the duration Td.
2) By reducing the value of the welding current Iw, the time until the temperature detection signal Hd ≧ temperature reference value Ht is extended so that the welding can be performed to the end.
3) Welding is stopped spontaneously at a location where welding can be resumed by the time duration Td elapses. And after cooling a welding torch, welding is restarted smoothly from the location.

  This figure shows a case where the welding operator receives a warning, determines that it is not possible to weld to the end within the duration Td, and implements the measures to increase the welding speed shown in 1) above at time t51. is there. For this reason, as shown in FIG. 6A, since the welding up to the end is completed at time t52 before the original scheduled welding end time t6, the energization of the welding current I2 ends at time t52. The period from time t51 to t52 is shorter than the duration Td, and the period from time t51 to t6 is longer than the duration Td. As shown in FIG. 5B, the value of the temperature detection signal Hd increases from time t5 to time t52, decreases until time t6, and further decreases during the rest period from time t6 to t7. As shown in FIG. 4D, the energization cut-off signal As remains at the Low level for the entire period. Even if an alarm is received at time t51, if the welding is continued without increasing the welding speed while maintaining the welding current I2, the energization cutoff signal As changes to a high level between time t52 and time t6. The energization of the welding current Iw is forcibly cut off.

  According to the above-described embodiment, when it is estimated that the temperature detection value from the temperature sensor that detects the condensate temperature from the welding torch reaches a predetermined temperature reference value after a predetermined duration time, A warning such as “The temperature will be exceeded in xx seconds” is issued. Since the welding operator is warned before the temperature is exceeded, change the welding conditions while receiving the warning to prevent the temperature from exceeding the temperature even if the workpiece is welded to the end. Can do. Further, since the welding operator can stop the welding at a position where the welding can be easily resumed, the welding can be resumed smoothly after the welding power source is stopped. For this reason, the energization of the welding current is forcibly cut off due to excessive temperature, and the welding is not suddenly stopped. Therefore, it is possible to prevent the work from being discarded or taking a lot of man-hours when resuming welding. Therefore, after protecting the welding torch from burning caused by excess usage, etc. It can suppress that production efficiency falls.

  In the embodiment described above, the case of plasma welding in which arc welding is non-consumable electrode arc welding has been described. However, the present invention relates to other non-consumable electrode arc welding and consumable electrode arc welding using a water-cooled welding torch. It can also be applied to.

1 Electrode 2 Base material 3 Plasma arc 4 Plasma nozzle 5 Shield nozzle 6 Cooling water
61 Water supply
62 Condensate As Energization cutoff signal HC Protection controller HD Temperature sensor Hd Temperature detection signal Hdd Temperature detection digital value Hs Temperature estimation value Ht Temperature reference value I1, I2 Welding current value Iw Welding current PS Welding power supply Td Duration Ts Sampling cycle Vw Welding voltage WC Cooling water circulator WT Welding torch ΔHd Rate of change

Claims (4)

In arc welding using a water-cooled welding torch, the temperature of the condensate flowing out of the welding torch is detected by a temperature sensor, and when the temperature detection value of this temperature sensor reaches a predetermined temperature reference value In the protection control method of the welding apparatus that cuts off the energization of the welding current,
When the temperature detection value is estimated to reach the temperature reference value after a predetermined time, an alarm is issued.
A protection control method for a welding apparatus. The estimation is performed based on a change rate of the temperature detection value.
The protection control method for a welding apparatus according to claim 1. The warning is performed by voice,
3. The protection control method for a welding apparatus according to claim 1, wherein the protection control method is used. When the alarm is issued, the welding conditions are automatically corrected so that the rate of increase of the temperature detection value decreases.
The protection control method for a welding apparatus according to any one of claims 1 to 3, wherein the protection control method is used.

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