JP2003105521A - Method of detecting arc failure in electric arc thermal spraying - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of precisely detecting arc failure without presence of an inspector or an operator, in a thermal-spraying process. SOLUTION: An electric voltage is applied to wire rods W1 , W2 for thermal spraying by a DC power source for thermal spraying, generating an arc between the wire rods. The molten metal produced by arc is blown into a surface 4 to be thermally sprayed, forming a thermally sprayed coating. The output current value of the DC power source is compared with the threshold value and binarized, with an arc cut-off state detected thereby and with the duration of this arc cut-off state measured. When duration of the arc cut-off state reaches a prescribed level, it is discriminated as occurrence of arc failure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an arc defect detection method in electric arc spraying, which detects that an arc defect has occurred in the process of performing electric arc spraying.

[0002]

2. Description of the Related Art An electric arc spraying method is known as a method for forming a metal film on the surface of a metal. In the electric arc thermal spraying method, a plurality of thermal spraying wire rods made of a metal material that constitutes the components of the thermal spray coating are fed toward the tip of the thermal spray gun by a feeding device provided in the thermal spray gun, and then inside the thermal spray gun. The contact tip and the thermal spray wire are brought into contact with each other, and power is supplied to the thermal spray wire from the thermal spray power supply through the contact tip.
As a result, an arc is generated between the tip portions of the wire for spraying, and the molten metal generated by this arc is placed on the gas flow and jetted toward the surface to be sprayed to form a sprayed coating on the surface to be sprayed. .

In the electric arc spraying apparatus, the feed frictional resistance is increased due to the abrasion of the feed path of the spraying wire, the supply of the wire from the reel for supplying the spraying wire is defective, and the spraying device for the spraying wire is defective. The feed rate of the thermal spray wire may change due to wear of the contact tip feeding the thermal spray wire, instantaneous welding of the thermal spray wire and the contact tip, and the like. If the feed rate of the thermal spraying wire fluctuates, excess or deficiency of the supply of the wire material to the arc generating portion may occur, and the arc may be disturbed. For example, if the wire feeding speed decreases,
Since the supply of the wire rod to the arc generating portion is insufficient, when the wire rod melted by the arc heat is blown out, a gap may be formed between the tip portions of the wire rod and the arc may be broken. At this time, since the supply of the thermal spraying wire is continued, the wire rods come into contact with each other with a slight interval, and the arc is regenerated. When such an operation is repeated, the state of arc interruption and the state of arc generation are repeated, and the spray current has an intermittent waveform.

During arc spraying, if the arc becomes unstable and the arc breaks up for a long time,
The thickness of the sprayed coating locally changes, or unmelted metal pieces adhere to the surface to be sprayed, causing defects in the sprayed coating,
This will reduce the quality of the sprayed coating.

In the present specification, a state in which the arc is interrupted to the extent that a defect may occur in the sprayed coating and a state in which the arc remains extinguished are called "arc defects".

Conventionally, in order to maintain the quality of the sprayed coating,
After the thermal spraying was completed, the appearance of the thermal spray coating was visually inspected.

[0007]

As described above, conventionally, the appearance of the thermal spray coating is visually inspected after completion of thermal spraying to check for the presence of thermal spray defects. It is often difficult to distinguish from the part, especially when the thickness of the film is thin locally, because it is often indistinguishable from the normal part,
By visual inspection, it was difficult to accurately determine the presence or absence of thermal spray defects.

It should be noted that during the thermal spraying construction
Visual inspection by an inspector (in the case of an automatic thermal spraying device) or an operator (in the case of a semi-automatic thermal spraying device), suspends the thermal spraying when an arc failure occurs, removes the cause of the arc failure, then Although restarting is possible, this method requires a considerably skilled inspector or worker to find out an arc defect from the arc generation state.

Further, when an arc defect occurs during the thermal spraying process, it is necessary to detect it and interrupt the process, but there is no method for accurately detecting the occurrence of the arc defect.

An object of the present invention is to detect an arc defect in electric arc spraying which can accurately detect an arc defect without requiring an inspector or an operator when performing electric arc spraying. To provide a method.

[0011]

SUMMARY OF THE INVENTION The present invention is produced by applying a voltage from a direct current spraying power source between a plurality of spraying wire rods to generate an arc between the tips of the plurality of spraying wire rods. It is an arc defect detection method for detecting that an arc defect has occurred in the process of performing arc spraying in which a sprayed molten metal is sprayed onto the sprayed surface to form a sprayed coating on the sprayed surface.

[0012] Normally, when electric arc spraying is performed using a DC spraying power source, if the feed rate of the spray wire changes, an arc will intermittently occur. At this time, the waveform of the output current of the spraying power source (referred to as the spraying current) becomes an intermittent waveform in which the energization period and the energization interruption period are repeated in synchronization with the arc interruption, and the spraying is accompanied by the change in the wire feed rate. The average value of the current and the duration of the arc break state change. When the time period in which the arc is cut off becomes long, the arc energy becomes insufficient and the amount of molten metal becomes insufficient, so that a thermal spray defect such as an insufficient film thickness of the thermal spray coating occurs.

Therefore, it is possible to detect the occurrence of an arc failure from the change in the average value of the spraying current.
The average value of the spray current fluctuates even during normal operation, and when an arc failure occurs, the average value of the spray current does not always show a remarkable change. It is difficult to accurately determine the presence or absence.

On the other hand, the duration of the arc disconnection state is
It is zero or almost constant under normal conditions, and shows a remarkable change only when an arc failure occurs.

Therefore, in the present invention, the value (magnitude) of the output current of the thermal spraying power source is less than the set threshold value, or the output voltage of the thermal spraying power source or the voltage between the thermal spraying wire rods. If the value (size) of is greater than or equal to the set threshold value, it is detected as an arc break condition, and the duration of this arc break condition is measured. Occurrence of arc failure is detected from the frequency of occurrence of a long arc break condition.

In electric arc spraying in which a voltage is applied from the direct current spraying power source to the spraying wire rod to generate an arc between the tip portions of the wire rod, in the state where the arc is generated between the tip portions of the wire rod, the spraying power source is used. When the value of the output current of is above a predetermined threshold value and the arc is extinguished, the value of the output current of the thermal power supply for spraying drops below the threshold value. Therefore, since the value of the output current of the thermal spraying power source has become lower than the predetermined threshold value, it is possible to detect that the arc disconnection state has occurred.

In this case, in order to measure the arc disconnection state and its duration, for example, the value of the output current of the thermal spraying power supply is compared with a threshold value for determining the arc disconnection state and binarized. , An arc state detection signal having a first value and a second value when the value of the output current is below the threshold value and above the threshold value, respectively. The time when the detection signal shows the first value may be measured by the timer.

Further, in electric arc spraying performed by applying a voltage from the DC spraying power source to the spraying wire rod, when an arc is generated between the tip portions of the wire rods, the output voltage of the spraying power supply or the space between the spraying wire rods is high. Voltage is below a specified threshold, and when the arc is extinguished, the output voltage of the spray power supply or the voltage between the spray wires exceeds the threshold. When the output voltage or the voltage value between the thermal spraying wire exceeds the threshold value, it is possible to detect the arc disconnection state. In this case, in order to measure the arc disconnection state and its duration, for example, the output voltage of the thermal spraying power supply or the value of the voltage between the thermal spray wire is compared with a threshold value for determining the arc disconnection state, Generates an arc state detection signal that takes a first value and a second value, respectively, when the output voltage or the voltage value between the thermal spray wire exceeds a threshold value and is below the threshold value. Then, the time during which the arc state detection signal shows the first value may be measured as the arc break time.

Currently, there are three types of direct current thermal spraying power sources: single-phase full-wave rectification direct-current power supply, three-phase full-wave rectification direct-current power supply, and inverter direct-current power supply. Recommended when the method of the present invention is applied. The spraying power sources used are a three-phase full-wave rectification type DC power source and an inverter type DC power source.

There are various possible methods for determining an arc failure using the arc disconnection state measured as described above and the duration thereof. The method disclosed in the present specification is summarized below. On the street.

In the first invention disclosed in the present application, it is determined that an arc failure has occurred when the duration of the arc disconnection state reaches the set determination value.

As mentioned above, the arc generated at the tip of the thermal spraying wire article is intermittently interrupted. However, the state in which the duration of the arc interrupted state is long is an abnormal state in any case, and the arc is defective. This is the condition that should be determined.

In the second aspect of the present invention, it is determined that the arc failure occurs when the duration of each of the arc break states continuously detected by the set number of determinations exceeds the set determination value. judge.

The state in which the arc interruption state in which the continuation time is relatively long is continuously generated is an apparent abnormal state, so that the arc interruption state in which the continuation time is equal to or less than the judgment value is not interposed.
When the arc disconnection state in which the duration exceeds the determination value is continuously detected the number of times of determination, it is determined that the arc failure has occurred.

In the third invention of the present application, the arc disconnection number measurement process of counting the number of times the arc disconnection state in which the duration exceeds the set determination value is detected during the set determination period Each time the value of output current or output voltage or the voltage between spraying wire materials is sampled, the measurement of the above judgment period is started and repeated, and in each arc break count measurement process, the arc break condition in which the duration exceeds the judgment value It is determined that an arc failure has occurred when the number of times of occurrences of is detected reaches the set determination number.

In the fourth invention of the present application, the arc breakage number measuring process for counting the number of times the arc breakage state exceeding the judgment value for which the duration time is set is detected during the set judgment period Each time the arc break condition that exceeds the judgment value is detected, the measurement of the judgment period is started and repeated, and the number of times the arc break condition that the duration exceeds the judgment value is detected is set in each arc break frequency measurement process. It is determined that an arc failure has occurred when the determined number of times has been reached.

If an arc disconnection state with a relatively long duration frequently occurs within a fixed time, the arc energy becomes insufficient and the amount of molten metal produced decreases, so that the probability of thermal spray failure increases. Therefore, in the third invention and the fourth invention of the present application, when the number of times of detecting the arc disconnection state exceeding the determination value for which the duration is set within the determination period reaches the set determination number (duration is It is determined that an arc defect has occurred when the frequency of occurrence of an arc break condition for a certain length reaches a determination value.

In the third invention, the measurement of the determination period is started each time the output current or output voltage of the thermal spraying power source or the value of the voltage between the thermal spraying wire rods is sampled, and the fourth aspect is started.
In the invention described above, the measurement of the determination period is started every time the arc disconnection state is detected, but the occurrence of the arc failure can be similarly detected by any method.

In the fifth invention of the present application, the integrated value calculation process for calculating the integrated value of the duration of the arc interruption state occurring within the set determination period is performed by the output current or output voltage of the spraying power source or the spraying wire rod. Measurement of the determination period is started every time the value of the voltage in between is sampled and repeated, and when the integrated value calculated in each integrated value calculation process reaches the set judgment value, an arc failure occurs. judge.

When the integrated value of the arc break times generated within a fixed time becomes large, the arc energy becomes insufficient and the probability of thermal spray abnormality increases, as in the case where the frequency of the arc break states increases. Therefore, as described above, as a result of calculating the integrated value of the durations of the arc interruption states that have occurred within the determination period, if the integrated value reaches the determination value, it is determined that an arc failure has occurred. To do.

In the method of the first aspect of the present invention, in which it is determined that an arc failure has occurred when the duration of the arc disconnection state reaches the determination value, the supply of the thermal spraying wire is stopped and the generation of the arc is stopped. Although an arc failure that keeps the state as it is can be reliably detected, it is not possible to detect an arc failure state in which a relatively long arc interruption state frequently occurs although the duration does not reach the determination value.

Further, in the second to fourth inventions for detecting the arc failure from the occurrence frequency of the arc disconnection state, there is a possibility that the arc disconnection state having a long duration cannot be detected as the arc failure.

Therefore, in order to obtain a high quality sprayed coating and to properly detect any arc failure, it is preferable to combine the first to fifth inventions appropriately. .

Therefore, in a preferred embodiment of the present invention, an arc abnormality determination process of making an abnormality determination when the duration of the arc disconnection state reaches a set determination value, and detection is performed continuously for a set number of determinations. The arc failure judgment process that performs an abnormality judgment when the duration of each arc break status exceeds the set judgment value, and the arc break status where the duration exceeds the set judgment value is set. The number of judgments is set by repeating the process of measuring the number of arc breaks that counts the number of times detected during the judgment period, and setting the number of times the arc break condition in which the duration exceeds the judgment value is detected in each process of measuring the number of arc breaks. It repeats the arc abnormality determination process that performs an abnormality determination when the temperature reaches the limit, and the integrated value calculation process that calculates the integrated value of the duration of the arc interruption state that occurred within the set determination period. Therefore, the abnormality determination is performed in parallel with the determination process of performing an abnormality determination when the integrated value calculated in each integrated value calculation process reaches a set determination value, and the abnormality determination is performed in any one of these determination processes. It is determined that the arc failure has occurred when is performed.

In another preferred aspect of the present invention, an arc abnormality determination process of performing an abnormality determination when the duration of the arc disconnection state reaches a set determination value, and continuously detecting a set number of determinations. Each of the specified arc break conditions has an arc abnormality determination process that performs an abnormality judgment when the duration exceeds the set judgment value, and the arc break state in which the duration exceeds the set judgment value is set. The number of times the arc disconnection number is detected during the determination period is repeated, and the number of times the arc disconnection state in which the duration exceeds the determination value is detected in each arc disconnection frequency measurement process is set. It is judged that an arc failure has occurred when the abnormality judgment is made in any of these judgment processes. That.

Further, in another preferred aspect of the present invention, the abnormality determination is performed when the duration of each of the arc disconnection states continuously detected by the set determination number exceeds the set determination value. Repeat the arc breakage determination process to perform and the arc breakage count measurement process that counts the number of times the arc breakage state exceeds the judgment value for which the duration is set and is detected during the set judgment period. An arc abnormality determination process that performs an abnormality determination when the number of times an arc disconnection state in which the duration exceeds the determination value is detected in the measurement process reaches the set determination number, and an arc disconnection that occurs within the set determination period. Repeat the integrated value calculation process to calculate the integrated value of the state duration, and perform an abnormality judgment when the integrated value calculated in each integrated value calculation process reaches the set judgment value. Carried out in parallel and click abnormality determination process,
It is determined that an arc failure has occurred when an abnormality determination is made in any of these determination processes.

Note that the combination of the judgment methods is not limited to the above example, and for example, the judgment values for which the respective durations of the arc disconnection states continuously detected by the set judgment times are set. Arc abnormality determination process that performs an abnormality determination when exceeding the limit, and the arc disconnection number measurement process that counts the number of times the arc disconnection state exceeds the determination value for which the duration is set and is detected during the set determination period. And an arc abnormality determination process of performing abnormality determination when the number of times the duration of the arc disconnection exceeding the determination value is detected in each arc disconnection number measurement process reaches the set determination number. The determination process may be performed in parallel, and it may be determined that an arc failure has occurred when an abnormality determination is performed in any of these determination processes.

In addition, the arc disconnection number measurement process of counting the number of times the arc disconnection state in which the duration exceeds the set determination value is detected during the set determination period is repeatedly performed. An arc abnormality determination process in which an abnormality determination is performed when the number of times the arc disconnection state in which the duration exceeds the determination value is reached reaches a set determination number,
The integrated value calculation process that calculates the integrated value of the duration of the arc disconnection state that occurred within the set judgment period was repeated, and the integrated value calculated in each integrated value calculation process reached the set judgment value. Even if it is determined that an arc failure has occurred when the abnormality determination is performed in either of these determination processes, the two determination processes including the arc abnormality determination process that occasionally performs the abnormality determination are performed in parallel. Good.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of the construction of an apparatus for carrying out the arc failure detection method of the present invention. In FIG. 1, reference numeral 1 is a wire rod for thermal spraying in which a first wire W1 for thermal spraying is wound. The first reel 2 as a supply source and the second wire W2 for thermal spraying
Is a second reel serving as a supply source of the wire material for thermal spraying. 3 is a thermal spray gun. The illustrated spray gun 3 has wire feeding devices 301 and 302 for feeding the first and second wire rods W1 and W2 by sandwiching them between a feeding roller and a pressing roller, respectively, and wire feeding devices 301 and 302. A point on the axis OO along the thermal spraying direction (the direction of spraying the molten metal fine particles) of the thermal spraying wire rods W1 and W2 fed to the surface to be sprayed (the surface on which the sprayed coating is formed) 4 at a predetermined feeding speed by And second wire guide tube 3 for guiding toward
03 and 304. Wire guide tube 303
Nozzles 304 and 304 are nozzles, and these nozzles make the tip of each of the thermal spraying wire rods W1 and W2 a thermal spray axis [axis line along the injection direction of the molten metal (spraying direction)].
It is provided so as to be directed to one point (arc generation point) A on OO. Each of the wire guide tubes 303 and 304 is made of a conductive material, and a contact tip that makes electrical contact with the wire is provided at the tip of each, and a voltage is applied between the thermal spray wires W1 and W2 through the contact tip. It

Reference numeral 305 is a gas supply pipe for generating a gas flow G which is blown to the arc generating portion along the spray axis. A nozzle for ejecting a conical gas stream that converges at a point on the spray axis in front of the arc generation point A may be provided.

Reference numeral 5 is a main body of the thermal spraying apparatus. Inside the main body 5,
A DC spraying power source that outputs a DC voltage applied between the wires W1 and W2, and a gas supply source that supplies gas (usually air) to the gas supply pipe 305 are provided. The gas supply source provided in the main body 5 is connected to the gas supply pipe 305 through the pipe 6.
, And the output terminal of the thermal power supply for spraying is connected to the contact tip at the tip of the wire guide tubes 303, 304 through the feeder lines 7, 8.

A current detector 9 for detecting the output current of the thermal spraying power source is attached to the power supply line 8, and the output signal (voltage signal) of the current detector 9 is set by a setting device 10 for setting a threshold value. It is input to the comparator 11 together with the output. 12
Is a computer having a CPU, RAM, ROM, timer, etc., and the output of the comparator 11 is input to the port B of the computer 12.

The computer 12 executes a predetermined program stored in the ROM to perform a series of processes necessary for determining the arc failure.

That is, when the arc spraying is started, the computer 12 gives a sampling command to the current detector 9 at a constant cycle so that the output current of the spraying power source is sampled.

The current detector 9 detects the magnitude of the output current (spraying current) I of the spraying power source 5 every time a sampling command is given from the computer 12, and the detected value (sampling value) is sent to the comparator 11. give. The comparator 11 compares the sampling value of the output current supplied from the current detector 9 with a threshold value, and when the sampling value of the output current is less than the threshold value and is above the threshold value. Occasionally, an arc state detection signal Sarc having a first value and a second value is generated. In this example, the comparator 11
An arc state detection signal generation circuit 13 is configured by the reference signal generation source 10 and the reference signal generation source 10.

Here, when the value of the output current of the thermal spraying power source is below the threshold value (when the arc is extinguished), the output of the comparator 11 becomes high level (H level), and the thermal spraying is performed. It is assumed that the output of the comparator 11 becomes low level (L level) when the value of the output current of the power supply for power supply is equal to or higher than the threshold value.

In this case, the computer 12 uses the comparator 11
When the potential of the port B to which the output terminal of is connected is recognized to be at the H level, the occurrence of an arc interruption state is detected, and each time the potential of the port B becomes at the H level (arc state detection). Every time the value of the signal Sarc becomes the first value), a timer is started to cause the timer to perform a time counting operation, and when the potential of the port B changes to the L level, the time counting operation of the timer is stopped. The measured value is stored in the RAM as the duration of the arc break state.

The computer 12 detects the arc disconnection state and measures the duration of the arc disconnection state as described above, and uses these results to determine the arc abnormality determination process based on the duration of the arc disconnection state. , An arc abnormality determination process based on the number of continuous arc interruption occurrences, an arc abnormality determination process based on the frequency of arc interruption state occurrences, and an arc abnormality determination process based on an integrated value of the arc interruption state durations are performed in parallel, When an abnormality determination is performed in any of these determination processes, it is determined that an arc defect that causes a thermal spray abnormality has occurred.

In each arc abnormality determination process, the arc abnormality is determined as follows.

(1) Arc Abnormality Judgment Process Based on Arc Break State Duration The abnormality judgment is performed in this judgment process when it is detected that the duration of the arc cut state exceeds the set judgment value. FIG. 2 shows an example of a timing chart showing the spray current waveform, the waveform of the arc state detection signal Sarc, the timer timing operation, and the arc failure determination signal in this determination process.
Shown in (A) to (D).

FIG. 2A shows the waveform of the spraying current I detected by the current detector 9, and FIG. 2B shows the comparator 11.
It shows the arc state detection signal Sarc output from the. When the arc is off, the arc state detection signal Sarc
Indicates the H level (first value), and when the arc is generated, the arc state detection signal Sarc indicates the L level (second value). FIG. 2C shows the timekeeping operation of the timer in the computer. The timer performs the timekeeping operation while the arc state detection signal Sarc is at H level, and measures the duration of the arc break state. . When the duration of this arc break state reaches the judgment value T1 (T1 = 0.05 sec in the illustrated example), the computer makes an abnormality judgment and outputs an arc failure judgment signal as shown in FIG. 2 (D). Generate So. In the illustrated example, the arc failure determination signal So is generated because the duration of the arc disconnection state exceeds the determination value T1 at time t1. Indicated arc failure determination signal So
Is a signal indicating an H level (high level) when an arc defect has occurred and an L level (low level) when an arc defect has not occurred.

In the illustrated example, the arc failure determination signal So is kept at the H level (the status indicating that the arc failure has occurred) until the arc disconnection state is resolved and the timer is reset at time t2. However, it is not always necessary to do so, and the arc failure determination signal So may be set to the H level for a short time when the duration of the arc disconnection state exceeds the determination value T1 at time t1. The arc failure determination signal So may be maintained at the H level even if the arc disconnection state is resolved at time t2.

In the example shown in FIG. 2, the arc defect determination signal So is set to the H level when the arc defect occurs, but the arc defect determination signal H level is set when the arc defect does not occur. Alternatively, the arc failure determination signal may be set to L bell when the arc failure occurs.

The arc determination failure signal So can be used as a signal for operating an alarm or as a command for interrupting the thermal spraying while the arc thermal spraying is being automatically performed.

(2) Arc Abnormality Judgment Process Based on the Number of Continuous Arc Breaks Occurred In this judgment process, a judgment value is set for which the respective durations of the arc break states continuously detected the set number of judgments are set. If it exceeds the limit, the abnormality is judged.
An example of a timing chart for explaining this determination process is shown in FIGS. 3 (A) to 3 (F).

FIG. 3A shows the waveform of the spraying current I detected by the current detector 9, and FIG. 3B shows the arc state detection signal Sarc output from the comparator 11.
Further, FIG. 3C shows the time counting operation of the timer in the computer, and FIG.
The arc cut detection signal Scut generated when the value exceeds 2. FIG. 3E shows the count value Nix of the number of times of continuous arc breakage, and FIG. 3F shows the arc failure determination signal. The number of continuous arc breakage occurrences Nix in FIG. 3 (E) is the number of times the arc breakage state in which the duration exceeds the determination value is continuously generated without interposing the arc breakage state in which the duration is equal to or less than the reference value, This is the number of times the arc cut detection signal Scut shown in FIG.

In this determination process, a remarkable arc disconnection state (duration is longer than the determination value T2) used for the arc failure determination is selected from a series of arc disconnection states, and the selected arc disconnection states are continuous. Then, when the number of occurrences reaches the set determination number, it is determined that the arc is defective.
Therefore, the computer 12 measures the time during which the arc state detection signal Sarc supplied from the comparator 11 is at the H level, and when the time exceeds the judgment value T2, the arc cut detection signal Scut is generated. By counting the number of times the arc break detection signal Scut is generated by the counter that is reset when the arc break condition whose duration is equal to or less than the judgment value T2 disappears, a remarkable arc break condition in which the duration exceeds the judgment value T2 is obtained. The number of times of continuous occurrence (the number of times of continuous arc interruption) is counted.

Therefore, the computer 12 uses the built-in counter as an arc break counter, and
The arc break detection signal Scut shown in (D) is applied to the count input terminal of the arc break counter, and the arc break detection signal Sarc generated when the arc break condition whose duration is less than the judgment value T2 is eliminated is changed from the H level to the L level. A reset signal is applied to the reset terminal of the arc break counter at the trailing edge of.

Therefore, the arc break counter is shown in FIG.
Each time the arc cut detection signal Scut shown in (D) is generated, the count value is increased by "1", the arc cut state where the duration is less than the judgment value T2 is eliminated, and the arc state detection signal Sarc is changed from the H level to the L level. When it falls to 0, it is reset and its count value is returned to "0".

In the illustrated example, when the arc break detection signal Scut rises at time t1, as shown in FIG.
The count value of the counter (the number of continuous arc breaks) became "1", but the duration of the arc break condition that occurred at time t2 did not reach the judgment value, and the arc re-generated at time t3 and the arc condition continued. Since the detection signal Sarc falls from the H level to the L level, the arc break counter is reset and the continuous arc break occurrence frequency Nix is returned to "0".

Next, since the duration of the arc break state generated at time t4 reaches the judgment value at time t5 and the arc break detection signal is generated again, the continuous arc break occurrence frequency Nix becomes "1", and then at times t6 and t7. Since the arc break detection signal Scut is continuously generated at, the times of continuous arc breaks are "2" and "3" at times t6 and t7, respectively. After that, at time t8, the arc disconnection state in which the duration is less than the judgment value disappears,
Since the arc has occurred again, the arc break counter is reset and the continuous arc break occurrence count Nix is returned to "0".

In this example, the number of judgments of the continuous arc interruption occurrence count Nix is set to "2", so that the time t
When the number of continuous arc interruption occurrences Nix becomes “2” in No. 6, as shown in FIG.
Is at the H level.

(3) Judgment process based on the frequency of occurrence of an arc break condition In this judgment process, an arc break condition that counts the number of times an arc break condition in which the duration exceeds the set judgment value is detected during the set judgment period. The number of times of measuring the number of times of arc is repeated, and when the number of times of detecting an arc broken state in which the duration exceeds the judgment value in each of the steps of measuring the number of times of breaking of the arc reaches the set judgment number, the abnormality judgment is performed.

A timing chart showing the operation of this determination process is shown in FIG. (A) to (D) of the figure respectively show the output current (spraying current) I of the DC spraying power source, the arc state detection signal Sarc, the timer operation, and the arc break detection signal S, respectively.
It is cut. Further, FIG. 4 (E) shows an arc break detection signal Scu.
The count value of the number of times t is generated, and FIG. 6 (F) is the arc failure determination signal So.

In this determination process, the duration is the determination value T3
A remarkable arc disconnection state exceeding 10 is detected as an arc disconnection state to be counted, and the number of times the arc disconnection state occurs within the determination period Ta is counted. Therefore, the computer 12 causes the arc state detection signal Sarc shown in FIG.
4 (D) when the time when H indicates the H level (first value) (duration of arc disconnection state) reaches the judgment value T3.
An arc break detection signal is generated as shown in.

The computer 12 uses the rising edges t11, t12, t13, and t13 of the arc break detection signal Scut shown in FIG.
... causes the counter to perform counting operation (increment the count value by "1"). The computer also determines the determination period Ta at the falling edges t21, t22, t23, ... Of the arc break detection signal Scut.
The time counting operation of the timer for measuring
When the measurement of the determination period Ta is completed at 1, t32, ..., The timing operation is stopped. In this way, the process of counting the arc break detection signal Scut generated during the measurement of the determination period Ta is referred to as the arc break frequency measurement process. Then, each time the arc break detection signal Scut is generated, the determination period T
The measurement of a is started and the above-described arc interruption frequency measurement process is repeated. When the number of occurrences of the arc interruption detection signal Scut reaches the determination frequency in each arc interruption frequency measurement process, the arc failure determination signal So is generated.

In the example shown in FIG. 4, the arc break detection signal S
The number of cut occurrences (the number of occurrences of an arc break state in which the duration exceeds the determination value T3) is set to "2". In the determination period Ta from time t21 to time t31,
Since the arc failure detection signal S0 is generated only once, the arc failure determination signal S0 is not generated, but in the determination period Ta from time t22 to time t32, the arc failure detection signal Scut is generated twice, so the second time. Arc failure determination signal So at time t13 when the arc break detection signal of
Is occurring.

In the example shown in FIG. 4, the duration is the judgment value T
Every time an arc disconnection state exceeding 3 is detected (each time the arc disconnection detection signal Scut is generated), the measurement of the determination period Ta is started, and the process of measuring the number of arc disconnections is repeated to continuously determine whether or not there is an arc defect. Although it is monitored, the output current or output voltage of the thermal spray power supply or the voltage between the thermal spray wires (in the above example, the output current of the thermal spray power supply)
The process of measuring the number of arc interruptions may be repeated by starting the measurement of the determination period Ta each time S is sampled.

(4) Judgment process based on the integrated value of the arc disconnection duration time In this judgment process, the integrated value calculation process for calculating the integrated value of the continuation time of the arc disconnection state generated within the set judgment period is repeated. The abnormality determination is performed when the integrated value calculated in each integrated value calculation process reaches the set determination value.

A time chart showing the operation of this determination process is shown in FIG. 5A and 5B show the spray current I and the arc state detection signal Sarc, respectively.
(C) and (D) show the integrated value of the duration of the arc break state and the arc failure determination signal So, respectively.

In this determination process, the state in which the sampled output current value of the spraying power source is less than the set threshold value is set as the arc disconnection state, and the arc state is detected as shown in FIG. 5 (B). By generating the signal Sarc, the arc disconnection state is detected, and the duration of the arc disconnection state is measured.

Then, the integrated value calculation process for calculating the integrated value Nm of the durations of the arc interruption states occurring within the set judgment period Tb is performed every time the output current (spraying current) I is sampled. The measurement is started and repeated, and when the integrated value calculated in each integrated value calculation process reaches the determination value, it is determined that the arc failure has occurred.

In the example shown in FIG. 5, the determination period Tb which starts at time t1 and ends at time t2 shown in FIG.
In the above, since the integrated value Na of the duration time of the arc disconnection state does not reach the judgment value Nas, the arc failure judgment signal is not generated. On the other hand, starting at time t3 and starting at time t4
In the determination period Tb that ends at, the integrated value Na reaches the determination value Nas at the time t4, so the arc failure determination signal S during one sampling interval from this time t4.
o has occurred.

In FIG. 5C, in order to avoid complication of the drawing, the next judgment period is started after one judgment period Tb is finished, but in reality, Since the determination period starts each time the spraying current is sampled, the integrated value calculation process is repeated in a state where a series of determination periods overlap, and the presence or absence of arc failure is constantly monitored.

In the above description, the value (magnitude) of the output current of the thermal spraying power source is compared with the threshold value to binarize the value so that different levels can be obtained depending on whether the arc is generated or not. The generated arc state detection signal is generated, but the state where the output voltage of the thermal spraying power supply or the voltage value (magnitude) between the thermal spray wires exceeds the set threshold value is detected as an arc break state. You can also do it. In this case, when the output voltage or the voltage between the spraying wire materials exceeds the threshold value, the first value is obtained, and the output voltage or the voltage value between the spraying wire materials falls below the threshold value. The binary signal that takes the second value may be generated as the arc state detection signal.

In the above description, the determination process is performed digitally, but the determination process may be performed in analog.

In the above description, an arc abnormality determination process based on the duration of the arc disconnection state, an arc abnormality determination process based on the number of times of continuous arc disconnection, an arc abnormality determination process based on the frequency of arc disconnection state occurrence, and an arc disconnection state duration time. Four judgment processes including the arc abnormality judgment process based on the integrated value are performed in parallel, and when an abnormality judgment is made in any one of these judgment processes, it is judged that an arc failure causing a spraying abnormality has occurred. However, as described in the section "Means for solving the problem", the arc abnormality determination process based on the duration of the arc interruption state, the arc abnormality determination process based on the number of continuous arc interruptions, and the arc interruption The three arc abnormality determination processes including the arc abnormality determination process based on the state occurrence frequency were performed in parallel, and the abnormality determination was performed in any one of these determination processes. It may be determined that the arc failure has occurred can.

Further, three arc abnormality determination processes, namely, an arc abnormality determination process based on the number of continuous arc interruption occurrences, an arc abnormality determination process based on the frequency of arc interruption state occurrences, and an arc abnormality determination process based on the integrated value of the arc interruption state durations are performed in parallel. Then, it may be determined that the arc failure has occurred when the abnormality determination is performed in any one of the determination processes.

Further, two arc abnormality determination processes, that is, an arc abnormality determination process based on the frequency of occurrence of the arc disconnection state and an arc abnormality determination process based on the integrated value of the arc disconnection state duration, are performed, and an abnormality is detected in any of these determination processes. When the determination is made, it may be determined that an arc failure has occurred, and there are two arcs, an arc abnormality determination process based on the number of continuous arc interruption occurrences and an arc abnormality determination process based on the integrated value of the arc interruption state duration. An abnormality determination process may be performed, and it may be determined that an arc failure has occurred when an abnormality determination is made in any of these determination processes.

If it is not necessary to detect the spraying abnormality so strictly, an arc abnormality determination process based on the duration of the arc disconnection state, an arc abnormality determination process based on the number of continuous arc disconnections, and an arc disconnection state occurrence frequency One of the arc abnormality determination process and the arc abnormality determination process based on the integrated value of the arc disconnection state duration is independently performed, and an arc defect occurs when the abnormality determination is performed in the determination process. You may make it determine that it did.

[0081]

As described above, according to the present invention, the arc disconnection state is detected from the output of the power supply for thermal spraying, the duration of the arc disconnection state is measured, and the duration of the arc disconnection state is determined by the judgment value. When the arc break condition exceeds the judgment value, the arc break condition continuously exceeds the judgment value for the judgment number of times, or the arc break condition exceeds the judgment value for the judgment number of times during the judgment period, or during the judgment period. Since it is determined that an arc defect has occurred when the integrated value of the durations of the arc disconnection states detected in step 1 has reached the determination value, it is possible to automatically detect arc defects that affect the thermal spray coating. There are advantages.

By applying the determination method of the present invention to automatic spraying, it is possible to automatically and surely detect a spraying abnormality caused by an arc failure, and therefore, it is possible to carry out thermal spraying with the spraying abnormality still occurring. It is possible to prevent non-defective products from being shipped.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a configuration example of an apparatus that implements an arc failure detection method of the present invention.

FIG. 2 is a time chart for explaining an abnormality determination operation according to the embodiment of the present invention.

FIG. 3 is a time chart for explaining an abnormality determination operation according to another embodiment of the present invention.

FIG. 4 is a time chart for explaining an abnormality determination operation of still another embodiment of the present invention.

FIG. 5 is a time chart for explaining an abnormality determination operation according to still another embodiment of the present invention.

[Explanation of symbols]

1, 2 ... Reel wound with thermal spray wire, 3 ... Thermal spray gun, 4
... sprayed surface, 5 ... spraying apparatus main body, 9 ... current detector, 10
... reference signal source, 11 ... comparator, 12 ... computer, 1
3 ... Arc state detection signal generation circuit.

Claims (10)

[Claims] 1. A molten metal produced by applying a voltage between a plurality of thermal spraying wire rods from a direct current thermal spraying power source to generate an arc between the tip portions of the plurality of thermal spraying wire rods, onto the surface to be sprayed. A method for detecting an arc defect in which a arc defect is generated in the process of performing arc spraying for forming a sprayed coating on the surface to be sprayed by injecting toward, wherein the value of the output current of the spraying power source is Detected as an arc break condition when it is below a set threshold value, or when the output voltage of the spraying power supply or the voltage value between the spraying wire rods is above a set threshold value. Then, the arc failure detection method in electric arc spraying, which measures the duration of the arc disconnection state and determines that an arc failure has occurred when the duration of the arc disconnection state reaches a set determination value. 2. A molten metal produced by applying a voltage from a direct-current spraying power source between a plurality of spraying wire rods to generate an arc between the tip portions of the plurality of spraying wire rods is applied to a surface to be sprayed. A method for detecting an arc defect in which a arc defect is generated in the process of performing arc spraying for forming a sprayed coating on the surface to be sprayed by injecting toward, wherein the value of the output current of the spraying power source is Detected as an arc break condition when it is below a set threshold value, or when the output voltage of the spraying power supply or the voltage value between the spraying wire rods is above a set threshold value. Then, the duration of the arc disconnection state is measured, and when the duration of each of the arc disconnection states detected continuously for the set number of determinations exceeds the set determination value, an arc failure occurs. Occurs And determining, arc fault detection method in the electric arc spraying was. 3. A molten metal produced by applying a voltage between a plurality of thermal spraying wire rods from a direct current thermal spraying power source to generate an arc between the tip portions of the plurality of thermal spraying wire rods, onto the surface to be sprayed. A method for detecting an arc defect in which a arc defect is generated in the process of performing arc spraying in which a sprayed coating is formed on the surface to be sprayed by spraying toward A state in which the output current, the output voltage, or the voltage value between the thermal spraying wire materials is sampled, and the sampled output current value of the thermal spraying power source is less than a set threshold value, or the thermal spraying power source. Of the output voltage or the value of the voltage between the thermal spray wire is equal to or more than a set threshold value is detected as an arc disconnection state, and the duration of the arc disconnection state is measured, The arc breakage number measuring process of counting the number of times the duration of the arc breakage exceeding the judgment value set is detected during the set judgment period, the output current or the output voltage or the voltage between the thermal spray wire Each time the value of is sampled, the measurement of the judgment period is started and repeated, and the number of times that the arc break condition exceeds the judgment value is detected during each arc break count measurement process. A method for detecting an arc defect in electric arc spraying, in which it is determined that an arc defect has occurred. 4. A molten metal produced by applying a voltage between a plurality of thermal spraying wire rods from a direct current thermal spraying power source to generate an arc between the tip ends of the plurality of thermal spraying wire rods is applied to a surface to be sprayed. A method for detecting an arc defect in which a arc defect is generated in the process of performing arc spraying for forming a sprayed coating on the surface to be sprayed by injecting toward, wherein the value of the output current of the spraying power source is Detected as an arc break condition when it is below a set threshold value, or when the output voltage of the spraying power supply or the voltage value between the spraying wire rods is above a set threshold value. Then, measuring the duration of the arc disconnection state, the arc disconnection number measurement process for counting the number of times the duration of the arc disconnection state exceeds the determination value is detected during the set determination period, The continuation The number of times the arc disconnection state in which the duration exceeds the judgment value is detected in the process of starting the measurement of the judgment period and repeating each time the arc disconnection state in which the interval exceeds the judgment value is detected. A method for detecting an arc defect in electric arc spraying, which determines that an arc defect has occurred when the set number of times has been reached. 5. A molten metal produced by applying a voltage between a plurality of thermal spraying wire rods from a direct current thermal spraying power source to generate an arc between the tips of the plurality of thermal spraying wire rods is applied to a surface to be sprayed. A method for detecting an arc defect in which a arc defect is generated in the process of performing arc spraying in which a sprayed coating is formed on the surface to be sprayed by spraying toward A state in which the output current value or the output voltage or the voltage value between the thermal spraying wire materials is sampled, and the sampled output current value of the thermal spraying power source is less than a set threshold value, or the thermal spraying The state in which the output voltage of the power supply for power supply or the voltage value between the above-mentioned thermal spray wires is equal to or greater than the set threshold value is detected as an arc break state, and the duration of the arc cut state is measured. , The integrated value calculation process for calculating the integrated value of the duration of the arc disconnection state that has occurred within the set judgment period, every time the value of the output current or the output voltage or the voltage between the thermal spray wire is sampled. Arc defect detection in electric arc spraying, in which measurement of the determination period is started and repeated, and it is determined that an arc defect has occurred when the integrated value calculated in each integrated value calculation process reaches a set determination value. Method. 6. A molten metal produced by applying a voltage between a plurality of thermal spraying wire rods from a direct current thermal spraying power source to generate an arc between the tip ends of the plurality of thermal spraying wire rods is applied to a surface to be sprayed. A method of detecting an arc defect in which a arc defect is generated in the process of performing arc spraying for forming a sprayed coating on the surface to be sprayed by injecting toward, wherein the value of the output current of the spraying power source is Detected as an arc break condition when it is below a set threshold value, or when the output voltage of the spraying power supply or the voltage value between the spraying wire rods is above a set threshold value. Then, the duration of the arc disconnection state is measured, and an arc abnormality determination process of performing an abnormality determination when the duration of the arc disconnection state reaches a set determination value, and a set number of determinations consecutively. Detected An arc abnormality determination process that performs an abnormality determination when the duration of each of the arc disconnection states exceeds the set determination value, and the determination that the arc disconnection state that exceeds the determination value that the duration setting is set is set. The number of times of arc breaks is counted to count the number of times detected during the period, and the number of times the arc break condition exceeds the judgment value in each arc break count measurement process is detected. When the arc abnormality determination process that performs an abnormality determination when it reaches, and the integrated value calculation process that calculates the integrated value of the duration of the arc interruption state that occurred within the set determination period are repeated, and in each integrated value calculation process When the calculated integrated value reaches the set judgment value, the arc abnormality judgment process that makes an abnormality judgment is performed in parallel, and an abnormality judgment is made in one of the arc abnormality judgment processes. And determining, arc fault detection method in an electric arc spraying arc fault occurs. 7. A molten metal produced by applying a voltage between a plurality of thermal spraying wire rods from a direct current thermal spraying power source to generate an arc between the tips of the plurality of thermal spraying wire rods is applied to a surface to be sprayed. A method for detecting an arc defect in which a arc defect is generated in the process of performing arc spraying for forming a sprayed coating on the surface to be sprayed by injecting toward, wherein the value of the output current of the spraying power source is Detected as an arc break condition when it is below a set threshold value, or when the output voltage of the spraying power supply or the voltage value between the spraying wire rods is above a set threshold value. Then, the duration of the arc disconnection state is measured, and an arc abnormality determination process of performing an abnormality determination when the duration of the arc disconnection state reaches a set determination value, and a set number of determinations consecutively. Detected An arc abnormality determination process that performs an abnormality determination when the duration of each of the arc disconnection states exceeds the set determination value, and a determination that the arc disconnection state that exceeds the determination value that the duration setting is set The number of times of arc breakage measurement that counts the number of times detected during the period is repeated, and the number of times the arc breakage state in which the duration exceeds the judgment value is detected in each arc breakage count process is set to the set judgment count. The arc failure determination in the electric arc spraying is performed in parallel with the arc failure determination process when the failure is reached, and it is determined that the arc failure has occurred when any of the arc failure determination steps is performed. Detection method. 8. A molten metal produced by applying a voltage from a direct-current spraying power source between a plurality of spraying wire rods to generate an arc between the tips of the plurality of spraying wire rods is applied to a surface to be sprayed. A method for detecting an arc defect in which a arc defect is generated in the process of performing arc spraying for forming a sprayed coating on the surface to be sprayed by injecting toward, wherein the value of the output current of the spraying power source is Detected as an arc break condition when it is below a set threshold value, or when the output voltage of the spraying power supply or the voltage value between the spraying wire rods is above a set threshold value. Then, the duration of the arc disconnection state is measured, and when the duration of each of the arc disconnection states detected continuously for the set number of determinations exceeds the set determination value, an abnormality determination is made. Do (5) Repeating the abnormal judgment process and the arc break count measurement process that counts the number of times the arc break condition exceeds the judgment value for which the duration is set and is detected during the set judgment period. In the process, an arc failure determination process that performs an abnormality determination when the number of times the arc disconnection state exceeds the determination value is detected reaches the set number of determination times, and the arc disconnection state that occurs within the set determination period The arc abnormality determination process of performing an abnormality determination when the integrated value calculation process of calculating the integrated value of the continuous time is repeatedly performed and the integrated value calculated in each integrated value calculation process reaches the set judgment value. An arc defect detection method in electric arc spraying, which is performed in parallel and determines that an arc defect has occurred when an abnormality determination is made in any of the arc abnormality determination processes. 9. The output current value of the thermal spraying power supply is compared with a threshold value for determining an arc break state, and when the output current value is less than the threshold value and the threshold value. When the value is greater than or equal to the value, the first value and the second value, respectively
The electric arc according to any one of claims 1 to 8, wherein an arc state detection signal having a value of 10 is generated, and a time during which the arc state detection signal shows a first value is detected as the arc break time. Arc failure detection method in thermal spraying. 10. The output voltage value or the spray wire material is compared by comparing the output voltage value of the spray power supply or the voltage value between the spray wire materials with a threshold value for determining an arc break state. An arc state detection signal having a first value and a second value is generated when the value of the voltage between exceeds the threshold value and below the threshold value, respectively, the arc state 9. The method of detecting an arc defect in electric arc spraying according to claim 1, wherein a time when a detection signal shows a first value is detected as the arc break time.