JPH0671442A - Method for calculating wire projecting length and arc length and device for observing welding state - Google Patents

Abstract

PURPOSE:To execute the welding working with high quality and reliability by calculating a wire projecting length with a functional formula making an average welding current, a wire feeding velocity and an average welding voltage between a chip and a base material as variables. CONSTITUTION:An average welding current is obtained by an average welding current detecting circuit 12 and inputted to an arithmetic circuit 15. A wire feeding velocity is obtained with a wire feeding velocity detecting circuit 12 and inputted to the arithmetic circuit 15. An average welding voltage between a chip 3 and a base material 6 is obtained by a voltage between chip and base material detecting circuit 14 and inputted to the arithmetic circuit 15. The arithmetic circuit 15 calculates the inputted data by the prescribed linear expression, obtains the wire projecting length from the top end of chip 3 to the top end of wire 4, and informs an operator of the length by an annunciator 18. Thereby, the operator can work so as to keep the wire projecting length constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calculating a wire protrusion length and an arc length in a consumable electrode type arc welding using a welding power source having a constant voltage characteristic, and a welding condition monitoring device.

[0002]

2. Description of the Related Art In arc welding using a consumable electrode (hereinafter referred to as a wire), the wire length from the tip of the tip to the tip of the wire (hereinafter referred to as the wire protrusion length) or the arc length from the surface of the base metal to the tip of the wire is constant. A good weld can be obtained by keeping the temperature at. "Sensing and Control in Arc Welding" (Welding Method Guidebook 2, May 1990)
Published on May 15th, Welding Society, pp. 2-94 to 2-99), the wire protrusion length L _E was calculated by the following formula 1, and the arc length L _A was calculated by the following formula 2. Mechanically correct the position of the welding torch based on the wire protrusion length L
_A technique for keeping _E or arc length L _A constant is disclosed.
However, since the arc voltage V _A in the equation 2 cannot be measured, the voltage drop V _E of the wire protrusion length L _E portion is first obtained by the equations 3 to 5, and the arc voltage V _A is obtained from the equation 6.

[0003]

[Equation 1]

[0004] Here, v: wire feed rate I _E: the effective current I _A: Average Current V _A: the arc voltage V: tip-base voltage V _E: voltage drop of the wire protruding length L _E moiety R: wire Resistance of protrusion length L _E part α: Difference between specific resistance and temperature coefficient of specific heat β: Temperature coefficient of specific resistance C _O : Specific heat J: Work equivalent of heat η _O : Specific resistance ρ: Specific gravity d: Wire diameter Also, K ₁ , K ₂ , K ₃ , K ₄ , K ₅ , and K ₆ are constants. Then, the constants K ₁ and K ₂ used in the above equation 1 are experimentally determined with respect to the protrusion length of the wire that is often used. Also,
Japanese Patent Publication No. 3-16227 discloses a technique of calculating a wire protrusion length by obtaining a value related to electric resistance from a voltage between a wire and a base material at the time of a short circuit and a current flowing through the wire.

[0005]

Generally, in arc welding of a constant speed wire feeding system using a welding power source having a constant voltage characteristic, the welding current value changes when the torch height changes. Then, the constant K ₁ in the former expression 1 of the above-mentioned prior art,
K ₂ may change depending on the value of the welding current, but the paper “Simultaneous control of penetration depth and bead height by multivariable welding parameter control” (“Welding Society Papers” Vol. 7, No. 1, 1989) Published on May 5th, Welding Society, pp. 21-26). Furthermore, the physical constants used for the calculation also use values determined under certain assumptions. As a result, the calculated wire protrusion length did not match the actually measured value, and a good welding result could not be obtained in some cases. As for the arc length, since the results of Equation 1 are used in Equations 3 and 5, the calculated value and the actually measured value do not match, as in the case of the wire protrusion length. on the other hand,
The latter of the above-mentioned prior arts is limited to short-circuit transfer arc welding. The object of the present invention is to solve the above problems, in the entire range of consumable electrode type arc welding using a welding power source of constant voltage characteristics, that is, in the entire range including not only short-circuit transfer but also globule transfer or spray transfer, It is an object of the present invention to provide a calculation method capable of accurately calculating a wire protrusion length and an arc length, and a welding state monitoring device.

[0006]

Means for Solving the Problems The above-mentioned problems include a condition setting device, a storage device connected to the condition setting device, and an arithmetic device connected to the storage device. The storage device is input to the condition setting device. At least one of the standard value of wire protrusion length and its permissible deviation, the standard value of arc length, its permissible deviation, the standard value of torch height and its permissible deviation, and the average welding current and wire feed rate And the average welding voltage between the tip and the base metal are stored as variables and the arithmetic result of the arithmetic unit, and the arithmetic unit averages the welding current and wire feed rate and the average between the tip and the base metal. The wire protrusion length, arc length, and torch height are calculated from the welding voltage measurement value at regular intervals, and a signal is output when the difference between each calculation result and the reference value exceeds the allowable deviation. By It is determined. Then, the above function formula is made to be a linear formula consisting of welding current, wire feeding speed, and voltage between tip and base metal, or the wire feeding speed is obtained from the set value of welding current, which can be more effectively solved. It

[0007]

The values of the wire protrusion length and the arc length obtained by the calculation are almost equal to the actual values. Therefore, if the value obtained by calculation is controlled so as to be a preset value, the wire protrusion length, arc length or torch height will always be constant.

[0008]

1 is a block diagram of an arc welding machine showing a first embodiment of the present invention. Reference numeral 1 denotes a constant voltage welding power source, and a welding current flows from an output side terminal 2 to an output side terminal 8 through a welding torch tip 3, a wire 4, an arc 5, a base metal 6, and a shunt 7 which are not shown. 9 is a wire feeding control circuit,
Wire feeding roller 11 connected to wire feeding motor 10
To supply the wire 4 to the chip 3. Reference numeral 12 denotes an average welding current detection circuit, which calculates the average welding current from the output of the shunt 7 and inputs it to the arithmetic circuit 15. Reference numeral 13 is a wire feeding speed detection circuit, which utilizes the fact that the wire feeding speed and the counter electromotive voltage of the wire feeding motor 10 are in a substantially proportional relationship, and the counter electromotive voltage of the wire feeding motor 10 is supplied to the arithmetic circuit 15. input. 1
4 is a chip-base material voltage detection circuit, which is a chip 3 and a base material 6
The average welding voltage between and is input to the arithmetic circuit 15. 15
Is an arithmetic circuit, which performs arithmetic operations described later. Reference numeral 16 denotes a keyboard for presetting at least one set of a reference wire protrusion length and its allowable deviation, a reference arc length, its allowable deviation, a reference torch height and its allowable deviation according to welding conditions. belongs to. Reference numeral 17 denotes a memory, which is the setting constant and arithmetic circuit 15 input from the keyboard 16.
The calculation result of is stored. Then, the arithmetic circuit 15 generates a voltage corresponding to the average welding current detected by the current detecting circuit 12 at a predetermined constant cycle, a voltage corresponding to the wire feeding speed detected by the wire feeding speed detecting circuit 13, and a tip The wire protrusion length and the arc length are calculated from the average welding voltage detected by the inter-base-material voltage detection circuit 14 by a previously stored functional expression, and the following calculation is further performed. That is, the wire protrusion length deviation, which is the difference between the reference wire protrusion length and the calculated wire protrusion length, the arc length deviation, which is the difference between the reference arc length and the calculated arc length, and the torch height are calculated. A torch height deviation, which is the difference between the reference torch height and the sum of the arc length and the wire protrusion length obtained in step 1, is calculated. Then, when any of the calculated absolute values of the deviation exceeds the corresponding allowable deviation, a signal for operating the alarm device 18 provided outside is output. Then, in order to make it easy for a beginner to keep the wire protrusion length or the arc length constant when performing semi-automatic welding, the alarm 18 corresponds to, for example, a large torch height deviation, an appropriate torch deviation, or a small deviation. A sound notification circuit that makes three levels of high sound, no sound, and low sound, or a sound notification circuit that emits different sounds when the deviation of the torch height is large and small, and a lamp that lights a lamp of another color Notification circuit, or +,-, 0
The liquid crystal notification circuit and the like are distinguished by the three symbols. In addition,
Reference numeral 19 is a current-voltage setting device for presetting the output of the constant voltage welding power source 1, and 20 is a welding power source control circuit for controlling the output of the constant voltage welding power source 1.

Before describing the operation, the equations for calculating the wire protrusion length and the arc length will be described. As described above, in the arc welding of the constant speed wire feeding method using the constant voltage welding power source, the welding current and the tip-base metal voltage also change when the torch height changes. Therefore, the arc length and the wire protrusion length are set as linear functions having the average welding current I, the wire feeding speed v, and the average welding voltage V between the tip and the base metal as variables, as shown in Equations 7 to 8. Arc length: l _a = A + B · I + C · V + D · v Formula 7 Wire protrusion length: l _e = E + F · I + G · V + H · v Formula 8 where A, B, C, D, E, F, G and H are It is a constant. Then, the constants A to H were determined as follows. That is, arc welding is performed by changing the welding current and torch height, and the data of the arc length or wire protrusion length from the base metal surface to the wire tip obtained by actual measurement with a CCD camera is used as the target variable, and the wire feeding is performed. The constants A to H were determined from the regression equation obtained by multiple regression analysis using the speed, the welding current, and the tip-base metal voltage as explanatory variables. For example, as the welding conditions, the welding current is changed to 80 to 350 A, and the torch height is changed to 10 to 35 mm.
When carbon dioxide arc welding is performed using φ mild steel wire, the constants A, B, C and D are A = 2.85 and B, respectively.
= -0.0278, C = 0.14, D = 0.04, E = 2
5.44, F = -0.20, G = 0.12, H = 0.20. Then, carbon dioxide arc welding was performed again, and the arc length and the wire protrusion length at this time were measured by a CCD camera. As a result, it was confirmed that they were in good agreement with those actually measured as shown in FIGS. 3 and 4.

The operation will be described below. Prior to welding, the welding condition, that is, the welding voltage value and the welding current value are set by the current / voltage setter 19 according to the designated work standard. Then, at least one set of the reference wire protrusion length and its allowable deviation, the reference arc length, its allowable deviation, the reference torch height, and its allowable deviation corresponding to the welding conditions is input by the keyboard 16. During the welding operation, the arithmetic circuit 15 has a predetermined constant cycle, for example, 0.1.
Every 1 second, average welding current detection circuit 12, wire feed speed detection circuit 13 and tip-base metal voltage detection circuit 14
The arc length and the wire protrusion length are calculated by the previously stored function formula using the signal from Furthermore, the wire protrusion length deviation, which is the difference between the reference wire protrusion length and the calculated wire protrusion length, the arc length deviation, which is the difference between the reference arc length and the calculated arc length, and the torch height are calculated. A torch height deviation, which is the difference between the reference torch height and the sum of the arc length and the wire protrusion length obtained in step 1, is calculated. When the wire protrusion length, arc length, or torch height fluctuates due to, for example, hand shake of the operator, and the absolute value of any deviation exceeds the corresponding allowable deviation, an alarm device 1 provided outside is provided.
8 is operated. Therefore, if the operator corrects the torch height according to the information displayed on the alarm 19 and returns the wire protrusion length or the arc length to a preset value, for example, the wire protrusion length becomes excessive and the shield deteriorates. Can be prevented. It should be noted that instead of the alarm 18, a start switch of the constant voltage welding power source 1 is connected to the arithmetic circuit 15 and started when the absolute value of the deviation of the wire protrusion length, the arc length or the torch height exceeds any allowable deviation. The switch may be turned off.

FIG. 2 is a block diagram of an automatic arc welding machine showing a second embodiment of the present invention. In the second embodiment, instead of the wire feeding speed detecting circuit 9 in the first embodiment, the set current value of the current / voltage setter 19 is taken into the arithmetic circuit 15 as the wire feeding speed, and the first embodiment is already performed. Used for various calculations explained in the example. The wire feeding speed is calculated by the equation 9. v = 0.633I-29.3 Formula 9 Here, v is a wire feeding speed (mm / s), and I is a set current (A). Further, the arithmetic circuit 15 includes a signal controller 2
A torch moving device 22 for moving the welding torch in the vertical direction is connected via 1. Further, from the keyboard 16, as in the first embodiment, among the preset reference wire protrusion length and its allowable deviation, the reference arc length and its allowable deviation, the reference torch height, and its allowable deviation. Of at least one set can be set, and the allowable value of the time change of each deviation can be set in advance. Then, the arithmetic circuit 15 also calculates the temporal change of the deviation, and when the temporal change of the deviation exceeds a preset allowable value, the output signal (hereinafter referred to as the first signal) described in the first embodiment is used. Is output). The other structure is the same as that of the first embodiment.

The operation will be described below. The operation in the second embodiment is that the torch moving device 22 is operated so that the wire protrusion length, the arc length and the torch height are made constant by the first output signal from the arithmetic circuit 15. It is substantially the same as the embodiment. And, it differs in the following points. That is, when the wire protrusion length and its permissible deviation, the arc length, its permissible deviation, the torch height and the temporal change of the permissible deviation exceed a preset permissible value, the moving speed of the torch is increased by the second signal. To do. As a result, the torch moves gradually when the change in the allowable deviation with time is gentle, and moves quickly when there is a step in the base metal, and a uniform weld can be obtained. If the second signal is used to change the interval of the sound of the alarm 18, for example,
It can also be applied to the first embodiment described above. In the above two embodiments, the wire feeding speed is the wire feeding roller 5
Of the constant voltage welding power source 1 may be used as an input instead of the voltage between the tip and the base metal. Further, the current detection circuit 12, the wire feeding speed detection circuit 13, and the chip-base material voltage detection circuit 14 may be omitted and the respective voltages may be directly input to the arithmetic circuit 15. Furthermore, the regression equations for l _a and l _e are I, V, v
It may be a function other than the linear function of.

[0013]

As described above, according to the present invention, the wire protrusion length, the arc length or the torch height is obtained from the measurable welding current, the wire feeding speed and the tip-base metal voltage. Is possible. Therefore, uniform welding results can be obtained in both semi-automatic arc welding and automatic arc welding. In particular, in the case of semi-automatic arc welding, the welding operator can maintain the torch height at an appropriate value by himself based on the information from the display device, and even a beginner can perform stable welding as well as a skilled operator. . as a result,
It is possible to prevent the welding operation from being interrupted due to the welding of the tip and the wire during welding and the welding defect due to the gas shield failure due to the torch height, and it is possible to achieve the welding of high quality and reliability and the improvement of the work efficiency.

[Brief description of drawings]

FIG. 1 is a block diagram of an arc welder showing a first embodiment of the present invention.

FIG. 2 is a block diagram of an arc welding machine showing a second embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a measured value of an arc length and a calculated value.

FIG. 4 is a diagram showing a relationship between a measured value of a wire protrusion length and a calculated value.

[Explanation of symbols]

 1 constant voltage welding power source 3 chip 4 wire 5 arc 7 shunt 10 wire feeding motor 12 current detection circuit 13 wire feeding speed detection circuit 14 chip-base metal voltage detection circuit 15 arithmetic circuit 16 keyboard 17 memory 18 alarm 19 Current / voltage setting device 20 Welding power supply control circuit 22 Torch moving device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiroku Fujiwara, Ibaraki Prefecture, 502 Kandachi-cho, Tsuchiura-shi, Ibaraki Machinery Research Institute Co., Ltd. Machinery Research Laboratory

Claims (12)

[Claims] 1. In consumable electrode type arc welding using a welding power source with a constant voltage characteristic, the wire protrusion length from the tip of the tip to the wire tip, the average welding current, the wire feeding speed, and the average welding voltage between the tip and the base metal are measured. A method for calculating a wire protrusion length, which is calculated by a functional expression using and as variables. 2. The method for calculating the wire protrusion length according to claim 1, wherein the wire feeding speed is obtained from the set value of the welding current. 3. The functional expression is a linear expression having variables of an average welding current, a wire feeding speed, and an average welding voltage between a tip and a base metal as a variable. The wire protrusion length calculation method described. 4. In consumable electrode type arc welding using a welding power source having a constant voltage characteristic, the arc length from the surface of the base metal to the tip of the wire, the average welding current, the wire feeding speed and the tip.
A method for calculating an arc length, which is calculated by a function formula having an average welding voltage between base materials as a variable. 5. The arc length calculating method according to claim 4, wherein the wire feeding speed is obtained from the set value of the welding current. 6. The function expression is a linear expression having variables of an average welding current, a wire feeding speed, and an average welding voltage between a tip and a base metal as a variable. The described arc length calculation method. 7. In the consumable electrode type arc welding using a welding power source having a constant voltage characteristic, the torch height from the base material surface to the tip of the tip is the wire protrusion length according to any one of claims 1 to 3. A torch height calculation method, which is calculated as a sum with the arc length according to any one of claims 4 to 6. 8. A condition setting device, a storage device connected to the condition setting device, and an arithmetic device connected to the storage device, wherein a reference value of a wire protrusion length for inputting the storage device to the condition setting device and The allowable deviation and the standard value of the arc length, the allowable deviation and the standard value of the torch height and at least one of the conditions of the allowable deviation, the average welding current, the wire feeding speed, and the average welding between the tip and the base metal. It is configured to store the function formula with voltage as a variable and the calculation result of the calculation device, and the calculation device is configured to measure the average welding current, wire feeding speed, and average welding voltage between the tip and the base metal at regular intervals. It is characterized in that the wire protrusion length, arc length, and torch height are calculated, and a signal is output when any of the differences between the respective calculation results and the reference value exceeds the corresponding allowable deviation. Stable Welding condition monitoring device for consumable electrode type arc welding using voltage-dependent welding power source. 9. The welding condition monitoring device according to claim 8, wherein the alarm device is connected to the arithmetic device, and the alarm device is operated by a signal output from the arithmetic device. 10. The wire protrusion length and its permissible deviation, the arc length, its permissible deviation, the torch height and its permissible deviation, as well as the permissible value of the time variation of each deviation, are stored in advance in a storage device, and the deviation is stored. 10. The welding state monitoring device according to claim 9, wherein the notification operation of the notification device is changed when the temporal change of the information exceeds a preset allowable value. 11. The welding state monitoring device according to claim 8, wherein the moving device of the torch is connected to the arithmetic device, and the moving device of the torch is operated by a signal output from the arithmetic device. . 12. The wire protrusion length and its permissible deviation, the arc length, its permissible deviation, the torch height and its permissible deviation, as well as the permissible value of the time variation of each deviation, are stored in advance in a storage device, and the deviation is stored. 12. The welding condition monitoring device according to claim 11, wherein the torch moving speed is increased when the temporal change of the torch exceeds a preset allowable value.