JP2002028781A - Measuring device for welding heat input - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely measure a welding heat input by detecting correctly a welding speed required when moving manually a welding torch. SOLUTION: By calculating a welding time by the changes of a rate of rise in temperature being measured by a first temperature sensor 6 installed at a specific distance in a position in parallel with the weld line of steel 1 which is a material to be welded and that being measured by a second temperature sensor 7, and by operating the welding speed from a time required actually for welding the steel 1 in a specific distance, the welding heat input is correctly obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding heat input measuring device for automatically measuring welding heat input when steel materials are joined by covered arc welding or semi-automatic welding.

[0002]

2. Description of the Related Art In welding a high-tensile steel sheet, if the welding heat input exceeds a certain value, bond embrittlement occurs. The cause of this phenomenon is that the cooling rate after welding becomes slow due to excessive welding heat input, so that the crystal grains in the weld bond become coarse and the toughness deteriorates. In order to prevent this bond embrittlement, in welding important steel structures, the upper limit of welding heat input is specified. For example, in the welding work of a spherical tank made of high-tensile steel, the welding heat input is measured for each welding pass according to the “Spherical Gas Holder Guideline (Japan Gas Association)”, and the upper limit is a constant value, for example, HW70. If 45
It is stipulated that welding is performed under the condition of 000 (joules / cm) or less.

[0003] The welding heat input Q (joule / cm) is given by Q = IEE / v, where I (A) is a welding current, E (V) is an arc voltage, and v (cm / min) is a welding speed. Is required. Among them, the welding current I and the arc voltage E are easily obtained from the set values of the welding power source or the actual measured values by an ammeter or a voltmeter. However, it is difficult to measure the welding speed v automatically even in covered arc welding and semi-automatic MAG welding because the welding torch is manually moved. For this reason, conventionally, a welding worker measures the time and distance of welding using one welding rod with a stopwatch and a ruler to determine the welding speed v.
As shown in JP-A-309534, two temperature sensors are provided at a fixed distance L in the vicinity of a welding line, and a time T ₀ during which a heat source by a welding torch passes between the two temperature sensors.
, And the welding speed v is obtained from v = L / T ₀ from the detected time T ₀ and the distance L between the two temperature sensors.

[0004]

As described above, the welding operator measures the time and distance of welding using one welding rod with a stopwatch and a ruler to obtain the welding speed v. In addition, many measuring operators are required to measure the welding speed v, and a measurement error may occur.

When the time T ₀ during which the welding heat source passes between the two temperature sensors is detected, and the welding speed v is obtained from the detected time T ₀ and the distance L between the two temperature sensors, the two If the arc is interrupted to exchange the welding rod between the temperature sensors, the time during which the arc is interrupted is also added, and it becomes impossible to measure the welding speed accurately.

The present invention has been made to solve the above-mentioned disadvantages, and provides a welding heat input measuring apparatus capable of accurately detecting a welding speed when a welding torch is manually moved and accurately measuring welding heat input. The purpose is to do so.

[0007]

SUMMARY OF THE INVENTION A welding heat input measuring apparatus according to the present invention is a welding heat input measuring apparatus for automatically measuring welding heat input when performing covered arc welding or semi-automatic welding. A current sensor, a first temperature sensor, a second temperature sensor, and a heat input measuring device, wherein the current sensor measures a welding current, and the first temperature sensor and the second temperature sensor are positioned parallel to the welding line. Are attached at a fixed distance to the workpiece to be welded, and each measures the temperature change due to the movement of the welding torch during welding, and the heat input measuring device determines the temperature rise rate of the temperature measured by the first temperature sensor in advance. When the specified reference rate of rise is exceeded, timing of the welding time is started, and the second
When the temperature rise rate of the temperature measured by the temperature sensor exceeds the reference rise rate, the measurement of the welding time is stopped, and the measured welding time and the distance between the first temperature sensor and the second temperature sensor are used. The welding speed is calculated, and the welding heat input is calculated from the calculated welding speed, welding current and arc voltage.

[0008] It is preferable that the reference rate of rise is set in a range of a temperature rise of 10 ° C to 30 ° C for a time interval of 30 seconds to 2 minutes.

Another welding heat input measuring device according to the present invention is:
A welding heat input measuring device that automatically measures welding heat input when performing covered arc welding or semi-automatic welding,
A current sensor, a first temperature sensor, a second temperature sensor, and a heat input measuring device, wherein the current sensor measures a welding current;
The first temperature sensor and the second temperature sensor are attached to the workpiece to be welded at a position parallel to the welding line at a fixed distance, and each measure a temperature change due to movement of a welding torch during welding, and a heat input measuring device. Starts the timing of the welding time when the temperature measured by the first temperature sensor exceeds a predetermined threshold, and the temperature measured by the second temperature sensor exceeds the predetermined threshold. In this case, the measurement of the welding time is stopped, the welding speed is calculated from the measured welding time and the distance between the first temperature sensor and the second temperature sensor, and the welding input is calculated from the calculated welding speed, welding current and arc voltage. It is characterized by calculating the amount of heat.

When the welding current measured by the current sensor becomes equal to or less than a predetermined threshold after the timing of the welding time is started, the timing of the welding time is interrupted, and when the welding current exceeds the threshold, the welding is stopped. You may want to restart timing.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A welding heat input measuring device according to the present invention has a current sensor, a first temperature sensor, a second temperature sensor, and a heat input measuring device. The current sensor measures a welding current supplied from the welding power source to the welding torch. The first temperature sensor and the second temperature sensor are attached to a workpiece to be welded at positions parallel to each other along a welding line at a fixed distance, and each measure a temperature change due to movement of a welding torch during welding, and receive heat input. When the measuring device is performing covered arc welding or semi-automatic welding, the change in the temperature measured by the first temperature sensor when the welding current measured by the current sensor exceeds a predetermined threshold. The timer starts the welding time when the rate of rise exceeds a predetermined reference rate of rise, and stops the timing of the welding time when the welding current measured by the current sensor falls below the threshold. When the time exceeds, the timing of the welding time is restarted, and when the change in the temperature measured by the second temperature sensor exceeds the reference rise rate, the timing of the welding time is stopped, and the total value of the counted welding time and First temperature Calculating a welding speed from capacitors and distance of the second temperature sensor. The welding heat input is calculated from the calculated welding speed, welding current and arc voltage.

[0012]

FIG. 1 is a block diagram of one embodiment of the present invention.
As shown in the drawing, a welding apparatus for joining steel material 1 along a welding line 2 by covered arc welding or semi-automatic welding includes a welding power source 3, a welding torch 4, a current sensor 5, and a first temperature sensor 6.
And a second temperature sensor 7 and a heat input measuring device 8. The current sensor 5 measures a welding current I supplied from the welding power source 3 to the welding torch 4 and outputs it to the heat input measuring device 8. The first temperature sensor 6 and the second temperature sensor 7 are composed of, for example, thermocouples and are attached to the position of the parallel steel material 1 along the welding line 2 at a predetermined distance L, and the movement of the welding torch 4 during welding Are measured and output to the heat input measuring device 8.

As shown in the block diagram of FIG. 2, the heat input measuring device 8 includes an input section 9, a time signal generating section 10, a binarization processing section 11, temperature rising rate calculating sections 12, 13 and a time start signal generating section. Section 14, timer end signal generating section 15, and welding time timer section 1
6, welding speed calculation unit 17, heat input calculation unit 18, and output unit 1
9 The input unit 9 receives a preset distance L between the first temperature sensor 6 and the second temperature sensor 7 and a welding current I and an arc voltage E which are preset or are actually measured by an ammeter or a voltmeter. input. The time signal generator 10 outputs a clock signal from the time when welding is started. The binarization processing unit 11 binarizes the welding current I measured by the current sensor 5 with a predetermined threshold value Ith. The temperature rise rate calculation unit 12 receives the temperature θ1 of the steel material 1 measured by the first temperature sensor 6 and the clock signal t output from the time signal generation unit 10 and receives the first temperature sensor 6.
Temperature rise rate Δθ1 / Δ of temperature θ1 of steel material 1 measured in
Calculate t. The temperature rise rate calculator 13 calculates the temperature θ2 of the steel material 1 measured by the second temperature sensor 7 and the time signal generator 1
The clock signal t output from 0 is input, and the temperature rise rate Δθ2 / Δt of the temperature θ2 of the steel material 1 measured by the second temperature sensor 7 is calculated. The timing start signal generator 14 compares the temperature rise rate Δθ1 / Δt of the temperature θ1 of the steel material 1 measured by the first temperature sensor 6 with a preset reference rise rate Δθth (degrees / second), and raises the temperature. Rate Δθ1 / Δt
Output a start time signal of the welding time when the value exceeds the reference rise rate Δθth. The timing end signal generation unit 15 calculates the temperature increase rate Δ of the temperature θ2 of the steel material 1 measured by the second temperature sensor 7.
θ2 / Δt is compared with the reference rise rate Δθth, and when the temperature rise rate Δθ2 / Δt exceeds the reference rise rate Δθth, a timing end signal for the welding time is output. The welding time timer 16 is 2
The welding current output DI output from the value processing unit 11, the timing start signal output from the timing start signal generation unit 14, and the timing end signal output from the timing end signal generation unit 15 are used for the first time.
The distance T between the temperature sensor 6 and the second temperature sensor 7 is measured as the time T1 during which the welding proceeds. Welding speed calculator 17
Is the time T1 output from the welding time timer 16 and the input 9
Temperature sensor 6 and second temperature sensor 7 output from
The welding speed v is calculated from the distance L. Heat input calculator 18
Calculates the heat input Q based on the welding speed v output from the welding speed calculation unit 17, the welding current I and the arc voltage E output from the input unit 9. The output unit 19 displays the heat input amount Q calculated by the heat input calculation unit 18 on the display unit 20 and outputs the heat input amount Q to the printer 21 for recording.

[0014] The steel material 1 is provided by the welding apparatus constructed as described above.
When welding is performed while moving the welding torch 4 along the welding line 2, the welding current I supplied from the welding power source 3 to the welding torch 4 is always measured by the current sensor 5 and the heat input measuring device 8 is used. Output to The binarization processing unit 10 of the heat input measurement device 8 binarizes the input welding current I and outputs a welding current output DI to the welding time timer 16 as shown in the waveform diagram of FIG. When performing this welding, in covered arc welding, the welding rod of the welding torch 4 is about 30 to 9
The welding current output DI becomes low when the welding rod of the welding torch 4 is replaced, for example, when the welding rod of the welding torch 4 is replaced. Become a high level. Further, the first temperature sensor 6 and the second temperature sensor 7 are respectively connected to the steel material 1 separated by a distance L.
Are measured and output to the heat input measuring device 8. The temperature rise rate calculation unit 12 of the heat input measurement device 8 includes:
The temperature rise rate Δθ1 / Δt of the temperature θ1 of the steel material 1 measured by the first temperature sensor 6 shown in FIG. 2 is calculated and output to the timekeeping start signal generation unit 14, and the temperature rise rate calculation unit 13 The temperature rise rate Δθ2 / Δt of the temperature θ2 of the steel material 1 measured by the temperature sensor 7 is calculated and output to the timing end signal generation unit 15.

When welding proceeds in this state and the welding torch 4 approaches the installation position of the first temperature sensor 6, the measured temperature θ1 of the first temperature sensor 6 increases as shown in FIG. The temperature rise rate Δθ1 / Δt changes rapidly. When the temperature rise rate Δθ1 / Δt of the temperature θ1 of the steel material 1 measured by the first temperature sensor 6 exceeds the preset reference rise rate Δθth, the timekeeping start signal generation unit 14 generates the first welding torch 4. Is determined to have reached the installation position of the temperature sensor 6, and a clocking start signal for the welding time is output. The welding time counting unit 16 starts counting the welding time when the time counting start signal is output from the time counting start signal generating unit 14 when the welding current output DI input from the binarization processing unit 11 is at a high level.
In this state, welding proceeds, and when the welding current I is cut off to replace the welding rod of the welding torch 4 and the welding current output DI becomes low, the welding time timer 16 stops measuring the welding time. , And temporarily holds the welding time T2 measured up to that time. When welding is resumed by replacing the welding rod of the welding torch 4 and the welding current output DI becomes high, the welding time timer 16 starts measuring the welding time again. When the welding torch 4 approaches the installation position of the second temperature sensor 7 in this state, the measured temperature θ2 of the second temperature sensor 7 increases, and the temperature increase rate Δθ2 / Δt changes rapidly. When the temperature rise rate Δθ2 / Δt of the temperature θ2 of the steel material 1 measured by the second temperature sensor 7 exceeds the preset reference rise rate Δθth, the timing end signal generator 16 sets the welding torch 4 to the second position. Is determined to have reached the installation position of the temperature sensor 7, and a time signal for terminating the welding time is output. The welding time timer 16 stops measuring the welding time when the timing end signal is output,
The welding time T3 measured up to that time and the temporarily held welding time T2 are added, and the time T1 during which welding has progressed between the first temperature sensor 6 and the second temperature sensor 7 during the distance L is determined as the welding speed. Output to the calculation unit 17. The welding speed calculation unit 17 calculates the welding speed v = L / T1 based on the time T1 output from the welding time counting unit 16 and the distance L between the first temperature sensor 6 and the second temperature sensor 7 output from the input unit 9. Is calculated and output to the heat input calculation unit 18. The heat input calculator 18 calculates the heat input Q = IEE based on the welding speed v output from the welding speed calculator 17, the welding current I output from the input unit 9, and the arc voltage E.
/ V is calculated and output to the output unit 19. The output unit 19 displays the heat input amount Q output from the heat input calculation unit 18 on the display unit 20 and outputs the heat input amount Q to the printer 21 for recording.

As described above, the temperature rise rate Δθ1 / of the welding current output DI and the temperature θ1 measured by the first temperature sensor 6 is shown.
The change of Δt and the temperature θ measured by the second temperature sensor 7
Since the welding time T1 for welding the distance L is calculated from the change in the temperature rise rate Δθ2 / Δt of 2, the time T1 during which the distance L is actually welded can be accurately detected, and the welding speed v can be accurately determined. Can be calculated. Therefore, the heat input Q can be accurately obtained.

In the above embodiment, a timing signal for starting the welding time is output from the change in the temperature rise rate Δθ1 / Δt of the temperature θ1 measured by the first temperature sensor 6 and measured by the second temperature sensor 7. The case where the timing end signal is output from the change of the temperature rise rate Δθ2 / Δt of the temperature θ2 has been described,
When the temperature θ1 measured by the first temperature sensor 6 exceeds a predetermined threshold value θth, a clocking start signal of the welding time is output, and the temperature θ measured by the second temperature sensor 7 is output.
Alternatively, a timing end signal may be output when 2 exceeds a predetermined threshold value θth.

[Specific Example 1] A plate thickness of 35 mm, a thickness of 1 m,
The welding heat input Q was measured by the heat input measuring device 8 using an X groove in which two steel materials 1 of high-tensile steel having a width of 50 cm were butted. The welding method was coated arc welding, the welding rod used was a low hydrogen type diameter of 4 mm, and the welding position was downward. The distance L between the first temperature sensor 6 and the second temperature sensor 7 is set to 10 cm at a position 30 mm from the welding line 2, and the measured temperatures θ 1 and θ 1 of the first temperature sensor 6 and the second temperature sensor 7 during welding. .theta.2 is stored, and the reference rise rate .DELTA..theta. with respect to the change .DELTA..theta.1, .DELTA..theta.2.
Let th be 20 degrees, and change Δθ1,
When Δθ2 exceeds the reference rise rate Δθth, it is determined that the welding torch 4 has approached the positions of the first temperature sensor 6 and the second temperature sensor 7. In addition, the welding current is constantly monitored and 50
(A) When it becomes the following, it is determined that welding has been interrupted,
During that period, the welding time timer 16 was temporarily stopped. The arc voltage was constant at 23V. The actual welding was performed under these conditions, and the heat input Q was measured by the heat input measuring device 8, and the welding heat input Q was measured manually as in the conventional case. FIG. 4 shows the result of repeating this measurement for 8 passes while changing the welding current. As shown in FIG. 4, it was confirmed that the welding heat input Q measured by the heat input measuring device 8 and the welding heat input Q measured manually were almost the same, and that the welding heat input Q could be accurately measured by the heat input measuring device 8. did it.

[Specific Example 2] As in the above specific example, the sheet thickness 2
2 pieces of high-strength steel 7 mm, 1 m long and 50 cm wide
5mm in diameter by sheathed arc welding using X butt joint
The welding heat input Q measured by the heat input measuring device 8 and the welding heat input Q manually measured when welding was performed in a downward position using a low hydrogen welding rod and the welding current was changed and eight passes were repeated were performed. As shown in FIG. Also in this case, the welding heat input Q measured by the heat input measuring device 8 and the welding heat input Q manually measured almost matched.

In each of the above specific examples, the measured temperatures θ1, θ
As a result of performing an experiment in which the reference value Δθth of the change of the predetermined time interval Δt in Step 2 is changed and the welding heat source approaches the first temperature sensor 6 and the second temperature sensor 7, the reference value Δθth is set to 1
If the temperature is set to 0 degrees or less, a temperature rise due to preheating is also detected. If the reference value Δθth is set to 30 degrees or more, when the welding heat input is small, the welding heat source approaches the first temperature sensor 6 and the second temperature sensor 7. Cannot be detected, and the reference value Δ
When θth was in the range of 10 degrees to 30 degrees, it was possible to reliably detect that the welding heat source had approached the first temperature sensor 6 and the second temperature sensor 7.

In the above embodiment, the heat input measuring device 8 detects the change in the welding current measured by the current sensor 5 and the change in the temperature measured by the first temperature sensor 6 and the first temperature sensor 7. Although the case where the welding time is calculated by calculating the welding time has been described, the operation of the heat input measuring device 8 is programmed and stored in a sequencer or a personal computer.
The welding heat input may be calculated by calculating the welding time with a sequencer or a personal computer.

[0022]

As described above, according to the present invention, a constant change is caused by a change in temperature measured by the first temperature sensor provided at a fixed distance and a change in temperature measured by the second temperature sensor. Since the welding time for welding the distance is calculated, it is possible to accurately detect the time for actually welding a certain distance, accurately calculate the welding speed, and accurately determine the welding heat input.

The welding time is calculated from a change in the actual welding current detected by the current sensor and a change in the temperature measured by the first temperature sensor and the temperature measured by the second temperature sensor provided at a fixed distance. Therefore, even when welding is interrupted, the actual welding time can be accurately detected, and the welding speed can be accurately calculated to accurately determine the welding heat input.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a heat input measurement device.

FIG. 3 is a waveform chart showing the operation of the embodiment.

FIG. 4 is a comparison diagram of an automatic heat input measurement result and a manual heat input measurement result according to Example 1.

FIG. 5 is a comparison diagram of an automatic heat input measurement result and a manual heat input measurement result according to a specific example 2.

[Explanation of symbols]

1; steel material; 2; welding wire; 3; welding power source; 4; welding torch; 5; current sensor; 6; first temperature sensor;
Temperature sensor, 8; heat input measuring device, 9; input unit, 10;
Time signal generator, 11; binarization processor, 12, 13; temperature rise rate calculator, 14; clock start signal generator, 15; clock end signal generator, 16; welding time clock, 17; welding speed Calculation unit 18; heat input calculation unit 19; output unit 20;
Display unit, 21; printer.

Claims (4)

[Claims] 1. A welding heat input measuring device for automatically measuring welding heat input when performing covered arc welding or semi-automatic welding, comprising: a current sensor, a first temperature sensor, a second temperature sensor, A heat input measuring device, wherein the current sensor measures a welding current, and the first temperature sensor and the second temperature sensor are attached to a workpiece to be welded at a position parallel to the welding line at a predetermined distance, and The heat input measuring device measures the welding time when the temperature rise rate of the temperature measured by the first temperature sensor exceeds a predetermined reference rise rate. Is started, and when the temperature rise rate of the temperature measured by the second temperature sensor exceeds the reference rise rate, the timing of the welding time is stopped.
A welding speed is calculated from a distance between the temperature sensor and the second temperature sensor, and a welding heat input amount is calculated from the calculated welding speed, welding current and arc voltage. 2. The welding heat input measuring apparatus according to claim 1, wherein said reference rate of rise is set in a range of a temperature rise of 10 ° C. to 30 ° C. for a time interval of 30 seconds to 2 minutes. 3. A welding heat input measuring device for automatically measuring welding heat input when performing covered arc welding or semi-automatic welding, comprising: a current sensor, a first temperature sensor, a second temperature sensor, A heat input measuring device, wherein the current sensor measures a welding current, and the first temperature sensor and the second temperature sensor are attached to a workpiece to be welded at a position parallel to the welding line at a predetermined distance, and The heat input measuring device starts measuring the welding time when the temperature measured by the first temperature sensor exceeds a predetermined threshold, and When the temperature measured by the temperature sensor exceeds a predetermined threshold, the measurement of the welding time is stopped, and the welding speed is determined based on the measured welding time and the distance between the first temperature sensor and the second temperature sensor. Calculate and calculate A welding heat input measuring device which calculates a welding heat input amount from a welding speed, a welding current and an arc voltage. 4. When the timing of the welding time is started and the welding current measured by the current sensor falls below a predetermined threshold, the timing of the welding time is interrupted, and when the welding current exceeds the threshold. 4. The welding heat input measuring device according to claim 1, wherein the measuring of the welding time is restarted.