• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention discloses a novel method of tracing weld lines in an automatic welding device. Conventionally, the tracking of the welding line was made by measuring the welding current, but the welding current was severely changed and the ripple noise was included due to the movement of the arc. In the present invention, the sampling time for measuring the welding current is synchronized with the weaving operation to sample while the welding head is stopped at both ends to prevent the change of welding current and the mixing of noise, and to compare the welding current between both ends and the reference current quickly. High quality beads can be formed by enabling accurate and accurate tracking.
    公开号:KR19990032821A
    申请号:KR1019970053974
    申请日:1997-10-21
    公开日:1999-05-15
    发明作者:임필주
    申请人:이해규；삼성중공업 주식회사；
    IPC主号:
    专利说明:

    Welding line tracking method of automatic welding device
    The present invention relates to an automatic welding device, and more particularly, to a method of automatically tracking a welding line and performing welding.
    Steel structures, such as ships and steel products, are generally manufactured in panel structures, and each panel is reinforced with various stiffeners such as stiffeners and ribs to reinforce it. It consists of a plate structure. On the other hand, since the above-mentioned ships are very large structures, a block method is used to finish each component part in order from the small assembly to the control assembly in order to improve the drying efficiency. As a result, a considerable amount of welding is required for each step of assembly, and automatic or semi-automatic welding is preferable for the uniformity of welding quality and the reduction of welding labor.
    However, in assembling between blocks, semi-automatic welding such as gravity welding is impossible due to various reinforcing materials, and manual welding is inevitable. For example, a plurality of girders may be used for fillet welding between bottom or deck and bulkheads crossing each other, or butt or seam welding between bottom blocks and the like. Since girder and stiffeners are attached to each other, the worker has to enter between the structures and join them by manual welding.
    Moreover, the deck or bottom material is the longitudinal strength member of the hull and the bulkhead is a watertight member, which is a considerable thick plate. The butt welding portion Wb between Ph, Ph ') and the fillet welding portion Wf with the vertical plate Pv are all welded by forming a plurality of beads. Especially in the case of CO 2 manual welding in which the penetration amount is smaller than that of other welding methods, as shown in FIG. 1 (B), the welding head W is zig-zag. If weaving is not carried out, the beads of sufficient width and shape cannot be formed.
    As such, welding the welding head continuously in a narrow place and performing the welding in a downward position poses considerable physical fatigue to the worker, especially in a sealed place in a steel structure such as a ship heated to several tens of degrees in the summer. Performing welding by inhaling harmful gases including CO 2 generated by this is a very painful task. This poor working environment, along with the non-uniformity of welding quality by manual welding, greatly reduced the productivity of the production of steel products such as ships.
    Accordingly, the automatic welding device as shown in Figure 2 is used, the illustrated example is disclosed in the Utility Model Registration No. 8305, 1993, in particular by the applicant.
    In Fig. 2, the automatic welding device rotates on a carriage 11 driven by a wheel R driven by a traveling motor, within a predetermined angle range in a direction orthogonal to the running direction of the carriage 11. A weaving box 12 having a weaving shaft 13 that is weaved is provided. An approximately L-shaped holder arm 15 is coupled to the weaving shaft 13 of the upper box 12, and a holder 14 coupled to the welding head W is provided at a tip thereof. The holder arm 15 is detachably coupled to the weaving shaft 13 so that butt welding or fillet welding of any angle can be performed according to the adjustment of the coupling angle with the weaving shaft 13.
    The holder 14 also has an adjustable coupling structure as shown so that a welding torch or other arc welding head of CO 2 welding can be supported.
    This automatic welding device is a kind of robot that selects a lookup table stored therein by adjusting the traveling control panel 19 and the weaving control panel 10 to automatically perform a predetermined welding operation. In order to perform the welding head (W) accurately weaving along the welding line, and when the position deviation is required to track the device to perform the welding to return to the correct position.
    Accordingly, the automatic welding device of Figure 2 is provided with a guide arm (16) for adjusting the length and angle on one side of the carriage 11, the guide roller 17 of the tip of the ship in the case of butt welding In the case of a stiffener, a separate guide plate 18, and fillet welding, the carriage 11 is guided by contacting the vertical plate Pv so that the welding head W follows the weld line.
    In the case of submerged arc welding or the like, in which the welding head W does not weave, the welding line can be traced only by guiding the carriage 11, but the CO 2 welding that the welding head W weaves, etc. In the case of the arc length is continuously changed by the weaving, it is possible to trace the weld seam to form a uniform bead only by adjusting the weaving range and the arc length together.
    However, in all arc welding including CO 2 welding, since the generation of arc is related to the distance and potential difference between two spaced points, the arc length, that is, the wire protruding to the tip of the welding head W, etc. Increasing the distance from the tip of the welding tip (T) to the base material to be welded (母 材; Ph, Ph ', Pv in FIGS. 1 (A) and (B), ie, the arc length, the resistance increases Therefore, the welding current is inversely reduced.
    Accordingly, by measuring the welding current during the welding process, it is possible to grasp the change in arc length, that is, the change in the distance between the welding tip and the base metal, so that the welding current can be used for tracking the weld line.
    In other words, by comparing the measured welding current with the set reference current to check the adequacy of the relative position between the welding head (W) and the base material (Ph, Ph ', Pv) by tracking the weld line by correcting the vertical and horizontal position.
    However, when the actual welding is performed in the automatic welding device applying the welding line tracking method of the current measurement method, the size and shape of the welded bead is not uniform and the straightness is poor.
    In order to solve the problems of the conventional method, the present inventors have analyzed and analyzed in detail the implementation mechanism of the conventional method.
    3 (A) shows a fillet weld between the horizontal plate Ph and the vertical plate Pv, the welding head W being weaved, i.e., rotated about a predetermined weaving center C. The tip of (T) draws an arc. On the other hand, the welded portion between the horizontal plate Ph and the vertical plate Pv forms a right angle instead of an arc, so that the arc length ℓ between the welding tip T and the base materials Ph and Pv is continuously changed to be at most Δℓ. It will have a change amount.
    This problem also applies to the butt welding portion between the horizontal plates Ph and Ph 'of FIG. 3 (B), so that the welding portions between the two horizontal plates Ph and Ph' are formed at a predetermined angle for penetration of the beads. Since it is improved by peeling, the arc length (l) changes similarly to the case of the fillet welding of FIG. 3 (A).
    As the arc length L continues to change during the weaving, the welding current I changes in the form of a sawtooth wave as shown in FIG. 3C as the time t elapses. Here, the minimum value Imin of the required welding current I is generated at the edge of the fillet welding or the boundary of the butt welding where the arc length is (L + ΔL) maximum, and the maximum value Imax is generated at the outer end of the weaving range.
    Moreover, while the welding head W is weaving from left to right or right to left, the arc state is very unstable because the welding tip T in which the arc moves moves between different points of the base material Ph, Ph ', Pv. As shown, a significantly large ripple current is generated in the measured welding current I.
    Therefore, if the welding current I is sampled for a predetermined sampling time at a predetermined sampling interval, sampling, i.e., the measured welding current I is randomly extracted for a part of the current to be changed. In addition, large ripple currents are inevitable as noise in the measurement.
    Accordingly, the welding current (I) measured by the conventional method does not have a significance that can represent a substantially accurate welding state, so that the adjustment of the welding conditions, that is, the welding line tracking, cannot be achieved.
    In addition, in order to use this large deviation welding current (I), it is inevitable to set the cumulative average value over a long period of time, such as several periods of incidence, to the measurement welding current. This is not achieved and there is a significant delay between measurement and adjustment, which inevitably leads to a decrease in the uniformity and linearity of the beads.
    In addition, in order to calibrate, an actual correction amount is determined by multiplying a current difference with a reference current by a predetermined gain, and the gain value is determined by an actual welding test of the corresponding welding device. However, according to the conventional method, since the test compensation amount for determining the gain value may have both positive and negative values, it is very difficult to determine the gain value.
    In addition, even if the gain value can be determined in this way, there is no way to determine whether the current difference measured in the weld seam tracking is caused by the deviation of the weaving range or by the change of the arc length within the weaving range. Seam tracing according to correction is practically very unreliable.
    However, the inventors of the present invention in the process of such a consideration is that the welding head (W) is to be paused for the change of direction when it reaches the left end or the right end of the weaving range, typically short dwell time for 0.1 to 0.4 seconds (dwell time Is that the welding current I is quite stable.
    This is considered to be because the arc is held between the fixed points while the welding head W is paused at the left and right ends of the weaving range, so that the stable arc can be maintained.
    Moreover, during the stop period at the outer end of the weaving range, as shown in Fig. 3C, the required welding current I becomes the maximum Imax, so that the comparison of the current difference is significant. That is, if the welding current measured at the left and right ends of the weaving range is larger than the theoretical reference current, the weaving range at the left or right end is excessive and vice versa, so that horizontal correction is possible. Vertical correction by the current difference from the reference current of the welding current, i.e. the relative distance of the welding tip T to the base material Ph, Ph'Pv, ie the protrusion of the welding tip T with respect to the welding head W. The length can be adjusted.
    1 (A) and (B) are schematic diagrams illustrating the types of welding sites and the welding process thereof.
    2 is a perspective view showing an example of an automatic welding device.
    Figure 3 (A) to (C) is a cross-sectional view and a current waveform diagram of the welding portion for explaining the problem of the conventional current sensing tracking method.
    4 is a current waveform diagram illustrating a method of the present invention.
    5 (A) and (B) are cross-sectional views of the welded portion for explaining the correction process according to the present invention,
    6 is a flow chart of the method of the present invention,
    7 is a detailed flow diagram of the portion of FIG. 6.
    <Description of Symbols for Main Parts of Drawings>
    W: welding head or torch T: welding tip (such as wire)
    C: Weaving center Ph, Ph ': Horizontal plate
    Pv: Vertical plate ℓ: Arc length
    ΔV: Vertical compensation amount ΔH1, ΔH2: Left and right horizontal compensation amount
    Based on this consideration, the method of the present invention synchronizes the measurement sampling time of the welding current with the weaving motion of the welding head to measure the welding current when the welding head is paused at both ends of the weaving range. The position of the welding head and the welding team is corrected by the current difference between the welding current and the reference current.
    Then, the welding current can be measured with a very accurate value without variation or ripple. In particular, since the position of the welding head is corrected by the current difference between left and right ends, it is possible to quickly and accurately correct, that is, to trace the weld line.
    Accordingly, the present invention can accurately track the welding line while maintaining the welding conditions uniformly, thereby forming a bead having a uniform shape and size with excellent linearity, thereby greatly improving the welding quality of the automatic welding apparatus.
    (Example)
    Such specific features and advantages of the present invention will become more apparent from the following description of the preferred embodiments with reference to the accompanying drawings.
    FIG. 4 basically shows the change of the welding current I according to the icing of the welding head W, similarly to FIG. 3 (B). In the present invention, the timing of measurement sampling of the welding current I is welded. In synchronization with the weaving operation of the head W, the sampling time is set while the welding head W reaches the left end or the right end of the weaving range and pauses. Then, basically there is no change and there is little ripple, so it is possible to measure stable welding current (I).
    Furthermore, during the stop period, as described above, the theoretical required welding current becomes Imax, which is the maximum value, so that the welding tip T at the position is compared with this Imax (actually the set reference current) and the measured welding current I. The adequacy of the relative position of can be immediately confirmed.
    That is, we can adjust the weaving range (horizontal correction) by checking the adequacy of the weaving range by the current difference at the left or right end, and it is possible to adjust the projection length (vertical correction) of the welding tip (T) for accurate tracking of welding line. This will be possible.
    5 (A) and (B) show a weld to be traced in accordance with the present invention, FIG. 5 (A) shows a fillet weld and FIG. 5 (B) shows a butt weld site. 5 (A) and (B), the weaving center (C) is basically a horizontal plate (Ph) and vertical plate (Pv) or horizontal plate by the provision of the guide arm 16 and the roller 17, etc. of FIG. It is in a state aligned with the center of the weld line between (Ph, Ph '), and horizontal correction is actually performed as an angle change of the weaving range at the left and right ends of the weaving range. The angle change of the weaving range at the left end and the right end is expressed as horizontal correction amounts ΔH1 and ΔH2, respectively.
    On the other hand, the vertical correction is made of a change in the projecting length of the welding tip (T) wire to the welding head (W), which is expressed as a vertical correction amount (ΔV).
    Hereinafter, a preferred embodiment of the present invention will be examined along the flow of FIGS. 6 and 7.
    In FIG. 6, the dotted line box represents the mechanical operation of the automatic welding device, that is, its running and weaving, etc., the solid line box represents the logic circuit operation within the control unit, and the dashed-dot box represents the mechanical operation such as transmission of a detection signal and a logic circuit. It indicates the connection operation between enemy operations.
    When the operation of the control unit is started in step 100, the welding device is started in step 110 to start a welding operation from a predetermined welding start position. In this case, when the welding line tracking circuit unit is configured independently of the control unit, the control unit turns it on.
    First, the welding head W is, for example, weaving from the right side to the left side (step 120), and when the welding head W reaches the left end of the weaving range when the welding head W reaches the left end of the weaving range, the controller generates a left end signal by an appropriate mechanical or circuit sensor. Detects this (step 130).
    Then, the welding head W is paused for a predetermined time (dwell time) of, for example, 0.1 to 0.4 seconds at the interruption to change the weaving direction. The current I is sampled and measured.
    The welding current (I) during the stop time is very stable compared to the weaving time, but also contains a ripple component, so it is preferable that the average welding current at the left end by sampling a plurality of data during the sampling time and averaging them. The average current I1 is calculated (step 150).
    Fig. 7 shows a preferred flow of the sampling of the left end current (step 140) and the calculation of the left end average current (step 150), which is also preferred for the sampling of the right end current and the calculation of the average current (step 180 and 190) and the sampling of the left end current after correction and the calculation of the average current (steps 240 and 250).
    First, referring to the current sampling process (steps 140, 180, and 240), the process of sampling and temporarily storing the current is repeated until a predetermined number of M samples are obtained for one sampling time (step 142) (step 141).
    When the M samples are measured, the average current is calculated in steps 150, 190, and 250. First, in step 151, the M averages the arithmetic mean of the M samples to obtain a temporary average. In the next steps 152 to 154, the current difference between each sample and its temporary average is calculated, and if the current difference exceeds a predetermined tolerance, the measurement of the sample is considered to include noise such as excessive ripple current and discarded.
    For example, if m samplings have a current difference that exceeds the tolerance, discard them, and then calculate the remaining Mm average currents in step 155 and use them as the left end average current (I1, I1 ') or the right end average current ( I2).
    Returning to the flow of FIG. 6 again, after the left end average current I1 has been calculated through steps 130 to 150 during the stop period at the left end, the welding head W is weaved from left to right and paused at the right end, and then The right end average current I2 is calculated through steps 170 to 190 which are substantially the same as steps 130 to 150.
    Then, since the average currents 11 and 12 of the left and right ends are measured and calculated, the right end correction amount can be calculated in step 200.
    First, the calculation of the horizontal compensation amount shows that the right end current difference is the difference between the right end average current and the left end average current. If the right end current difference is positive, the arc length at the right end of the weaving range (L in FIG. 3) is shorter than the left end, that is, the distance between the tip of the welding tip T and the base material Ph, Ph ', Pv is smaller. This means increasing the weaving range at the right end. Accordingly, the right end horizontal correction amount (ΔH2) is a quantity obtained by multiplying a positive current difference by a gain value (determined by the test as described above) according to the welding device characteristics, and weaving the right end horizontal correction amount (ΔH2) by the next left ice unit. Will increase the range.
    On the other hand, if the right side current difference is negative, this is the opposite. Therefore, the weaving range should be reduced when the right side horizontal correction amount (ΔH2) multiplied by the gain value is moved from the right side to the left side, but the horizontal correction amount is positive and negative. If it is possible to have all negative values, the welding quality is rather deteriorated. Therefore, when the right end current difference is negative, it is preferable that the right end horizontal correction amount ΔH2 is zero.
    Next, the vertical compensation amount ΔV is preferably calculated separately at the left end and the right end, and the right vertical compensation amount is determined by a test or the like by comparing the average current obtained by arithmetic average of the left and right average currents with a predetermined reference current. This is determined by multiplying the gain value. The reference current is a value set according to the required welding length, and the vertical correction amount is a correction amount for the protruding length of the welding tip T with respect to the welding head W as described above.
    When the calculation of the right end correction amount is completed in step 200, the correction amount is transmitted to the welding apparatus in step 210 to perform necessary correction. In step 220, the welding head W performs correction weaving from the right end to the left end. That is, the protrusion length of the welding tip T is adjusted according to the vertical correction amount calculated at the right end, and weaving is performed at the left end while the weaving range is adjusted according to the left end horizontal correction amount ΔH1 calculated above.
    Then, in steps 230 to 270, the left end correction amount is calculated and transmitted in the same process as in steps 170 to 210 at the right end described above, and in step 280, correction weaving is performed from the left end to the right end. In other words, the welding line is traced to the optimum welding condition.
    In the above, the vertical and horizontal correction amounts may be changed continuously according to the current difference, but in order to allow the mechanical element to perform the quick correction, stepwise control or limitation of the correction range is preferable.
    For example, the vertical compensation amount can be changed into a plurality of steps depending on the range of the current difference, for example, -0.4, -0.2, 0, +0.2, + 0.4mm, and the horizontal compensation amount is, for example, It is limited to 0 to 0.4 mm. Then, the mechanical elements of the welding apparatus can be operated step by step instead of continuously following the circuit calculated calculation amount, so that the operation can be surely performed. As a result, the weld line tracking function is improved and the shape of the bead is improved. It is possible to improve the welding quality such as linearity.
    In the present invention, since the horizontal correction amount only takes a positive value, that is, the negative correction is not performed at the left and right ends, the gain value is very easily determined when testing the device for determining the gain value. Will be improved. As described above, when the correction value has a real value during horizontal correction, it is possible to guarantee better welding quality by performing only positive correction as in the present invention rather than performing both negative and positive corrections.
    In addition, since the correction is made for each weaving without accumulating the measurement value for several times of weaving as in the prior art, it is possible to maintain the optimum welding condition at all times.
    As described above, according to the present invention, since the automatic welding apparatus tracks the welding line in the best welding condition, the welding quality of the automatic welding apparatus is greatly improved.
    权利要求:
    Claims (7)
    [1" claim-type="Currently amended] A method of tracking a weld line by measuring a welding current in an automatic welding device having a welding head protruding a welding tip and weaving a predetermined weaving range, the sampling time of measuring the welding current weaving motion of the welding head Synthesizing the welding current when the welding head is temporarily stopped at both ends of the weaving range, and correcting the position of the welding head and the welding tip by the current difference between the welding current and the reference current measured at both ends. Welding line tracking method of the automatic welding device characterized in that.
    [2" claim-type="Currently amended] The method of claim 1, wherein the horizontal correction of the welding head is performed in proportion to the current difference between the welding currents measured at both ends of the weaving range.
    [3" claim-type="Currently amended] The method according to claim 2, wherein horizontal correction is performed at an outer end thereof when the current difference between the welding currents is positive, and horizontal correction is not performed when negative.
    [4" claim-type="Currently amended] The method of claim 2, wherein the amount of horizontal correction is limited within a predetermined range in proportion to the current difference.
    [5" claim-type="Currently amended] The method of claim 1, wherein the vertical correction of the protrusion length of the welding tip with respect to the welding head is made in proportion to the current difference between the average current of the welding current measured at both ends of the weaving range and the reference current. How to track weld line of welding device.
    [6" claim-type="Currently amended] The method of claim 5, wherein the amount of the vertical correction is determined stepwise according to the range of the current difference.
    [7" claim-type="Currently amended] 2. The measurement of the welding current according to claim 1, wherein the measurement of the welding current is performed by arithmetically averaging the samples obtained by a plurality of measurements to obtain a temporary average, and then comparing the temporary average with each sample to discard the samples whose current difference exceeds the tolerance. The welding line tracking method of the automatic welding device, characterized in that the average current averaged the samples.
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    同族专利:
    公开号 | 公开日
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    1997-10-21|Application filed by 이해규, 삼성중공업 주식회사
    1997-10-21|Priority to KR1019970053974A
    1999-05-15|Publication of KR19990032821A
    优先权:
    申请号 | 申请日 | 专利标题
    KR1019970053974A|KR19990032821A|1997-10-21|1997-10-21|Welding line tracking method of automatic welding device|
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