JP2007289966A - Welding quality discriminating method and welding equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a welding quality discriminating method and welding equipment that can properly perform discrimination of normal/defective condition of a welding product. <P>SOLUTION: In discriminating welding quality in a welding process for a 9th product, normal/defective condition discriminating data E stored in a memory for discrimination data is corrected to be reduced in comparison with the initial value, on the basis of n=8 median value in the average electric current data h1-h8 of a first to an eighth product, and the reduced new normal/defective condition discriminating data EH (transfer threshold value) is used for the discrimination of the welding quality. When the normal/defective condition discriminating data (threshold value) is constant, wrong discrimination for the welding quality that could occur in accordance with the wear of a welding tip as a production quantity increases can be avoided; thus, discrimination accuracy can be improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to the welding quality of a product obtained by a welding process for a member to be welded, such as a welding current, a welding voltage, a wire supply speed, etc. (where welding conditions are determined) (hereinafter referred to as a welding physical quantity as appropriate). The welding quality determination method and the welding apparatus using a threshold value determined by at least one physical quantity (for example, welding current).

As an example of a conventional welding apparatus, there is an arc welding machine 1 shown in FIG. 3 (see Patent Document 1). The arc welding machine 1 shown in FIG. 3 forms an arc discharge between the welding torch 4 to which the wire 3 is supplied by the wire feed motor 2 and the member 5 to be welded, and welds the member 5 to be welded. To give. The welding torch 4 includes a welding tip 6 that is detachable.
The welding torch 4 and the member 5 to be welded are connected to a welding power source 8 via a cable 7. The welding power source 8 receives an input of the current command value B from the robot control panel 9 and supplies a welding current to the welding torch 4 and the member to be welded 5 through the cable 7. The welding power source 8 has a current sensor 13 that measures a current flowing through a welding circuit 12 including the cable 7, the welding torch 4, and the member to be welded 5 and inputs the current measurement value D to the robot control panel 9. ing.

The robot control panel 9 stores a main arithmetic circuit 15, a setting unit 16 for setting the welding conditions such as current and voltage, and the current command value B, and pass / fail judgment data determined corresponding to the current command value B. A determination data memory 17 and a data collection circuit 18 that collects a current measurement value D from the welding power source 8 and outputs the current measurement value D are provided.
The main arithmetic circuit 15 controls the current supply to the welding circuit 12 via the welding power source 8 and controls the wire feeding motor 2 via the welding power source 8 to adjust the wire feeding speed. The main arithmetic circuit 15 further compares the pass / fail judgment data E (see FIG. 4) and the current measurement value D from the welding power source 8, and based on the comparison result, the weld bead is determined whether it is normal or abnormal, and thus the member to be welded. The welding quality of the product obtained by the welding process for 5 is determined.

  As shown in FIG. 4, the pass / fail judgment data E is obtained from a normal range 20 corresponding to a region between the upper and lower reference current values t1U and t1L determined with the current command value B approximately as a center, and an upper reference current value t1U. The U1 warning range 21 and the U2 abnormal range 22 defined in the large current region, and the L1 warning range 23 and the L2 abnormal range 24 defined in the current region smaller than the lower reference current value t1L. The upper reference current value t1U and the lower reference current value t1L of the normal range 20 are about “current command value B + 15” [A] and “current command value B-15” [A], respectively. The boundary value t2U of the U2 abnormal range 22 is set to about “current command value B + 25” [A], and the boundary value t2L of the L1 warning range 23 / L2 abnormal range 24 is set to about “current command value B-25” [A]. ing.

In the welding process for the member 5 to be welded, a current having characteristics as shown in FIG. That is, at the start of the welding process, immediately before the end of the welding process, the current suddenly rises and falls, and a current having characteristics that change less than the rise and fall parts flows between the two.
In the determination by the main arithmetic circuit 15, a portion excluding the rising and falling portions of the current measurement value D from the welding power source 8 is used, and in this embodiment, one second has elapsed since the welding process was started. The measured current value D in a period (hereinafter referred to as a determination period) T until a predetermined time elapses from the point in time is used for the determination.

Then, as shown in FIG. 4, when the current measurement value D is within the normal range 20 in the determination period T, the main arithmetic circuit 15 determines that the weld bead is normal and the product is normal. To do.
Further, as shown in FIG. 4, the main arithmetic circuit 15 indicates that the measured current value D exceeds the U1 warning range 21 and indicates the U2 abnormal range 22, and the current measured value D indicates the value within the U2 abnormal range 22. When the state continues and exceeds a predetermined time Ta (for example, 2 seconds), it is determined that the weld bead is abnormal and the product is abnormal. Similarly, the state where the current measurement value D exceeds the L1 warning range 23 and indicates the value of the L2 abnormality range 24, and the current measurement value D indicates the value within the L2 abnormality range 24 continues for a specified time (for example, 2 2 seconds), it is determined that the weld bead is abnormal and the product is abnormal.
Japanese Patent Laid-Open No. 7-9186

  By the way, in the said welding quality determination method, the welding tip 6 is worn with the welding process for the member 5 to be welded, and the welding current decreases with the production of the product. On the other hand, the pass / fail judgment data E (determination threshold) is fixed. For this reason, the quality determination cannot be performed properly, and it may have been determined that it is abnormal (defective product) even though welding is performed normally. In other words, since the variation width G (see FIG. 5) of the average value (average current) of the current measurement value D exceeds the range between the boundary values t2U and t2L, the pass / fail judgment data E (determination threshold) is fixed. If this is done, it will not be possible to make an accurate determination.

The inventor of the present application performed measurement on an actual line to which the above-described conventional technology was applied, and obtained a measurement result shown in FIG. In the production process for obtaining the measurement result shown in FIG. 5, about 700 products (members to be welded 5) are targeted, and welding tips 6 are produced until about 700 products (members to be welded 5) are produced. Are exchanged five times (the arrow portion pointing downward in FIG. 5). In FIG. 5, the production number is taken on the horizontal axis, and the average value (average current) of the current measurement values D in the determination period T in FIG. 4 is taken on the vertical axis.
As shown in FIG. 5, the measurement result was obtained that the average current gradually decreased with production, and the average current before the replacement of the welding tip 6 was extremely small compared to immediately after the replacement. In such a portion where the average current is extremely small (an erroneous determination region surrounded by an ellipse 25 in FIG. 5), it may be determined as abnormal (defective product) even though welding is normally performed. There were many. In fact, in this measurement (about 700 products (members 5 to be welded)), about 30% was erroneously determined to be abnormal although it was normal.

  This invention is made | formed in view of the said situation, and it aims at providing the determination method and welding apparatus of the welding quality which can perform the quality determination of a welding product appropriately.

The invention according to claim 1 determines the welding quality of a product obtained by a welding process on a member to be welded based on a threshold value determined by at least one physical quantity among a plurality of physical quantities related to the welding process. A physical quantity data collecting step for collecting physical quantity data to be compared with the threshold value, and calculating the physical quantity average data by averaging the physical quantity data collected in the physical quantity data collecting step for each welding process of the product. An average data calculation step, and a threshold correction step for correcting the threshold based on the latest physical quantity average data among the physical quantity average data collected in the average data calculation step, .
According to a second aspect of the present invention, in the welding quality judgment method according to the first aspect, a welding current supplied from a welding power source is involved in the welding process, and the threshold value is determined by the welding current. And

According to a third aspect of the present invention, the welding quality of a product obtained by performing a welding process on a member to be welded and the welding process is based on a threshold value determined by at least one physical quantity among a plurality of physical quantities related to the welding process. A physical quantity data collecting means for collecting physical quantity data to be compared with the threshold value, and the physical quantity data collected by the physical quantity data collecting means for each welding process of the product to average the physical quantity average data. Average data calculation means for calculating the threshold value, and threshold correction means for correcting the threshold value based on the latest physical quantity average data among the physical quantity average data collected by the average data calculation means.
According to a fourth aspect of the present invention, in the welding apparatus according to the third aspect, the welding process involves a welding current supplied from a welding power source, and the threshold is determined by the welding current.

  According to the first to fourth aspects of the present invention, since the threshold value is corrected based on the latest physical quantity average data among the physical quantity average data, it is possible to determine the welding quality reflecting the welding process status, and accordingly, the determination accuracy. Can be improved.

Hereinafter, a welding quality determination method and welding apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. Members and parts equivalent to those shown in FIGS. 3 and 4 are denoted by the same reference numerals, and the description thereof is omitted as appropriate.
The arc welding machine 1A according to this embodiment is mainly different from the arc welding machine 1 shown in FIG. 3 in the following (1) to (3).
In the determination data memory 17, quality determination data E having the same contents as shown in FIG. 4 is stored in advance as initial values as shown in FIG. 2, and this quality determination data is obtained for up to eight products. The initial value of data E is used.
(1) The robot control panel 9 is provided with an average data calculation circuit 30 (average data calculation means) for calculating current average data corresponding to the average value of current in the determination period T.
(2) The robot control panel 9 includes an average data memory 31 connected to the main arithmetic circuit 15 and the average data calculation circuit 30. The average data memory 31 stores current average data, and the main arithmetic circuit 15 Current average data can be read from the average data memory 31.
(3) The main arithmetic circuit 15 rewrites the pass / fail judgment data E stored in the judgment data memory 17 by using the calculation result of the average data calculation means as will be described later, and a new pass / fail obtained by rewriting. Use judgment data EH to judge welding quality.

  In FIG. 1, the average data calculation circuit 30 provided to the robot control panel 9 is a product welding process for the current measurement value D (physical quantity data) collected by the data collection circuit 18 (physical quantity data collection means) (physical quantity data collection step). The current average data shown in the black circles (●) in FIG. Here, for convenience of explanation, the current average data shown in FIG. 2 is referred to as first, second,..., Twentieth current average data h1, h2,. In addition, the first, second,..., Twentieth current average data h1, h2,..., H20 are obtained corresponding to the product, and correspondingly, the product (including the member 5 to be welded) is also obtained. Are referred to as the first, second,..., Twentieth product for convenience.

The main arithmetic circuit 15 (threshold correction means) uses the quality determination data E (initial value) used when determining the welding quality for one product to determine whether the eight products welded immediately before the one product are processed. Of the current average data h, correction is performed (rewritten) based on current average data having a size at the center (for convenience, n = 8 median value). And the main arithmetic circuit 15 determines welding quality using the new quality determination data EH obtained by rewriting.
For example, when determining the welding quality for the ninth product, n = 8 median value in the current average data h1 to h8 of the first to eighth products (in this case, any one of the current average data h1, h5, and h8). The quality determination data E stored in the determination data memory 17 is corrected (rewritten) based on Similarly, the correction processing is performed on the pass / fail judgment data E stored in the judgment data memory 17 for the tenth product, the eleventh product,.
In the present embodiment, n = 8 median value constitutes the latest physical quantity average data of claim 1. In the present embodiment, the pass / fail judgment data E and the new pass / fail judgment data EH constitute a threshold value.

  Generally, if the welding tips 6 are not replaced as the number of production increases, the welding current decreases as the welding tips 6 are worn. New pass / fail judgment data EH obtained by correction based on the current average data h1 to h8 of the eight products is smaller than the initial value. For example, as shown in FIG. 2, when the initial value of the pass / fail judgment data E is the upper reference current value t1U in the normal range 20, the new upper reference current value a1U obtained by the correction is an increase in the number of production (FIG. 2). It becomes smaller as it goes to the right). Further, when the initial value of the pass / fail judgment data E is set to the lower reference current value t1L of the normal range 20, the new lower reference current value a1L obtained by the correction increases the number of production (the right direction in FIG. 2). ). That is, the corrected new normal range 20a tends to become smaller (downward trend) as shown in FIG. 2 as the number of production increases (in the right direction in FIG. 2). Similarly, the entire corrected new pass / fail judgment data EH including the boundary value t2U of the U1 warning range 21 / U2 abnormal range 22 and the boundary value t2L of the L1 warning range 23 / L2 abnormal range 24 is as described above. It shows the downward trend as well.

  The pass / fail judgment data E [threshold value] shown in FIG. 4 is a constant value regardless of an increase in the number of production, whereas this embodiment is a new value obtained by correction as the number of production increases. The pass / fail judgment data EH shows the characteristic of the lower right in FIG. Therefore, the new pass / fail judgment data EH obtained by the correction of the present embodiment can be regarded as moving downward with respect to the pass / fail judgment data E [threshold] shown in FIG. New pass / fail judgment data EH obtained by the correction can be expressed as a movement threshold value. The corrected new quality determination data EH is also referred to as a movement threshold as appropriate.

The operation of the welding apparatus configured as described above will be described.
In the present embodiment, when determining the welding quality in the welding process for the member to be welded 5, for the first to eighth products (member to be welded 5), the initial pass / fail judgment data E stored in the judgment data memory 17 is used. The value is used, and the pass / fail judgment data E is corrected for products after the ninth product. Prior to the determination of the welding quality in the welding process for the ninth product, the average data calculation circuit 30 calculates the current average data h1 to h8 of the first to eighth products based on the data from the data collection circuit 18 (average Data calculation step).

  Subsequently, when determining the welding quality in the welding process for the ninth product, the pass / fail determination data stored in the determination data memory 17 based on the n = 8 median value in the current average data h1 to h8 of the first to eighth products. E is corrected so as to be smaller than the initial value (threshold correction step). And the new quality determination data EH (movement threshold value) made small are used for determination of welding quality.

In the prior art in which the welding current generally decreases due to wear of the welding tips 6 accompanying an increase in the number of production and the threshold value is constant, it may be determined that the product is abnormal even though the weld bead is normal. It was easy. On the other hand, in the present embodiment, the quality determination data EH obtained by the correction by correcting the quality determination data E based on the n = 8 median value in the current average data h1 to h8 of the first to eighth products. The (threshold value) is a value reflecting the wear state of the welding tips 6 as the number of production increases.
For this reason, although the welding bead is normal, it is possible to reliably avoid the occurrence of the problems of the prior art that determine that the product is an abnormal product, and improve the determination accuracy.

Further, in the determination of the welding quality in the welding process for the tenth product, the determination data is based on the n = 8 median value in the current average data h2 to h9 of the second to ninth products, as in the example of the ninth product. The pass / fail judgment data E stored in the memory 17 is corrected so as to be smaller than the initial value (threshold correction step). And the new quality determination data EH (movement threshold value) made small are used for determination of welding quality.
Hereinafter, similarly, the quality determination data E stored in the determination data memory 17 is corrected for the eleventh product, the twelfth product,..., Similarly to the ninth product and the tenth product, It is possible to reliably avoid the problems of the prior art and improve the determination accuracy.

  In the above embodiment, n = 8 median value constitutes the most recent physical quantity average data of claim 1, but instead of n = 8 median value, n = 3 median value, n = 10 median value, etc. The median value may be used. Further, instead of n = 8 median value, an average value of a plurality of physical quantity average data immediately before may be used, or one physical quantity average data immediately before may be used.

  In the above embodiment, the case where the physical quantity data is the welding current (welding) is taken as an example, but the present invention is not limited to this, and voltage or electric power may be used as the physical quantity data. Further, as the physical quantity data, a wire feed load resistance value, a wire feed speed, or the number of short-circuits caused by an excess of the wire feed amount may be used.

It is a figure showing typically an arc welding machine concerning one embodiment of the present invention. It is a figure for demonstrating correction | amendment of the quality determination data by the arc welder of FIG. It is a figure which shows typically an example of the conventional arc welding machine. It is a figure which shows the quality determination data stored in the quality determination data memory of FIG. It is a figure for showing the problem of the arc welding machine of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A ... Arc welding machine (welding apparatus), 15 ... Main arithmetic circuit (threshold correction means), 17 ... Memory for judgment data, 18 ... Data collection circuit (physical quantity data collection means), 30 ... Average data calculation circuit (average data calculation) means).

Claims (4)

A welding quality determination method for determining a welding quality of a product obtained by a welding process on a member to be welded based on a threshold value determined by at least one physical quantity among a plurality of physical quantities related to the welding process,
A physical quantity data collecting step for collecting physical quantity data to be compared with the threshold;
An average data calculation step of calculating the physical quantity average data by averaging the physical quantity data collected in the physical quantity data collection step for each welding process of the product;
A welding quality determination method, comprising: a threshold correction step of correcting the threshold based on the latest physical quantity average data among the physical quantity average data collected in the average data calculation step.   The welding quality determination method according to claim 1, wherein the welding process involves a welding current supplied from a welding power source, and the threshold value is determined by the welding current. A welding apparatus that performs a welding process on a member to be welded and determines a welding quality of a product obtained by the welding process based on a threshold value determined by at least one physical quantity among a plurality of physical quantities related to the welding process. ,
Physical quantity data collecting means for collecting physical quantity data to be compared with the threshold;
Average data calculation means for calculating physical quantity average data by averaging the physical quantity data collected by the physical quantity data collection means for each welding process of the product;
A welding apparatus comprising: threshold correction means for correcting the threshold based on the latest physical quantity average data among the physical quantity average data collected by the average data calculation means. The welding apparatus according to claim 3, wherein a welding current supplied by a welding power source is involved in the welding process, and the threshold value is determined by the welding current.

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