KR100340808B1 - A method for adjusting level of lower electrode wheel in mash seam welding - Google Patents

Abstract

PURPOSE: A method for adjusting level of lower electrode wheel in mash seam welding is provided to carry out superior mash seam welding by minimizing generation of spatter due to sectional generation of heat and adjusting lower electrode wheel, thereby removing difference of circumferential speed. CONSTITUTION: The method for adjusting level of lower electrode wheel in mash seam welding comprises the steps of performing dressing by judging whether or not to carry out dressing on electrode wheels of a mash seam welding machine; setting a target thickness of a welding part and a theoretical highest point level of the lower electrode wheel per types and thickness of steel when dressing process for the electrode wheels is completed; measuring an actual highest point level of the lower electrode wheel by moving a displacement sensor to surface measuring position of the lower electrode when the theoretical highest point level of the lower electrode wheel is set; setting the lower electrode wheel as the theoretical highest point level by moving the lower electrode up and down so that the actual highest point level of the lower electrode wheel measured by the displacement sensor is coincided with the set theoretical highest point level; and performing welding when setting of level of the lower electrode wheel is completed.

Description

A mesh depth welding method for welding by adjusting the level of the lower electrode wheel. {A METHOD FOR ADJUSTING LEVEL OF LOWER ELECTRODE WHEEL IN MASH SEAM WELDING}

The present invention relates to a mesh core welding method for welding by adjusting the level of the lower electrode wheel, more specifically, the thickness of the weld obtained when welding by welding conditions set according to the steel type and thickness of the strip to be welded before welding And set the highest level of the lower electrode wheel in advance, measure the highest point level of the currently-dressed lower electrode wheel with a level sensor, and then adjust the level of the lower electrode wheel to be welded by adjusting the level setting value of the lower electrode wheel. It relates to a mesh core welding method of welding by adjusting.

In general, mash seam welding, as illustrated in FIG. 1, overlaps the trailing end of the preceding strip 5 with the leading end of the trailing strip 4 by a predetermined amount, and the welding current direction 11. The upper electrode roll 6 is lowered toward the lower electrode roll 7 while pressing the overlapped portions of the preceding and following strips while welding the same.

At this time, in order to obtain a good welding quality, both the material properties of the material to be welded, the selection of appropriate welding conditions, and the stable operation of the welding machine must be satisfied.

In this case, the outer peripheral surfaces of the electrode wheels 6 and 7 are very rough due to the heat generated by the contact resistance with the leading and trailing strips 5 and 4, and in the severe case, the step is generated at the outer peripheral surfaces. There is a distraction.

Therefore, in the related art, the surface of the electrode wheel is cut to a predetermined thickness by using a dresser, a bite, or the like on the outer peripheral surfaces of the electrode wheels 6 and 7 so as to always be kept smooth.

However, due to frequent cutting, the outer diameters of the electrode wheels 6 and 7 are gradually reduced, so that the level of the lower electrode wheel 7 is gradually lower than the upper surface of the entry lower clamp 2-2. As shown in Fig. 2, the density of the current flowing in the welded portion is maximized at the contact portion between the lower electrode wheel and the strip, and also locally heated at the welded portion between the leading strip 5 and the trailing strip 4, as shown in FIG. It is very difficult to obtain the melting phenomenon over the entire contact surface between the strips, which causes welding failure.

In order to improve such a conventional problem, in Japanese Patent Laid-Open No. 4-22582, as shown in FIG. 3, the lower end of the dresser 9 is located on the same line as the upper surfaces of the entry and exit lower clamps 2-2 and 3-2. Is installed.

And when dressing while raising the lower electrode wheel 7 using the ball screw 21, the highest level of the lower electrode wheel always maintains the same level as the upper surface of the entry-side lower clamps 2-2 and 3-2. It becomes possible.

However, this technique shows that when the strength of the strips 4 and 5 is high and thick, as shown in FIG. 4, the concentration of the welding current is rather increased between the contacts between the upper electrode wheel 6 and the preceding strip 5 and between the strips. Concentration is concentrated on a part of the interface and causes sparks and poor welding.

In addition, due to the local concentration of the current, the upper electrode wheel may be contaminated by surface melting and the lower electrode wheel may be severely damaged due to plastic deformation due to high pressing force acting during welding. In this case, the upper and lower electrode wheels 6, The dressing amount of 7) is much higher than usual.

Therefore, the diameter imbalance of the upper and lower electrode wheels 6 and 7 causes a difference in the circumferential speed at the contact portion between the electrode and the strips 5 and 4, which in turn deepens the difference in electrical resistance of the contact portion.

In order to achieve the above object, the present invention is set in advance the thickness of the weld portion and the highest level of the lower electrode wheel obtained when welding by welding conditions set according to the steel type and thickness of the strip to be welded before welding, It is an object of the present invention to provide a mesh core welding method for welding by adjusting a level of a lower electrode wheel that is adjusted by a level setting value of a lower electrode wheel after measuring a peak level of a current lower electrode wheel.

1 is a state diagram showing a welding state of a general mesh seam welder,

2 is a state diagram showing a welding state of a conventional mesh seam welder,

Figure 3 is a front view (a) and one side view (b), showing a conventional mesh core welder,

4 is a state diagram showing a welding state of a conventional mesh seam welder;

Figure 5 is a side view showing a mesh core welder for a mesh core welding method for welding by adjusting the level of the lower electrode wheel according to the present invention;

6 is a state diagram of measuring the level of the lower electrode wheel by a mesh core welding method of welding by adjusting the level of the lower electrode wheel according to the present invention;

7 is a flow chart showing a mesh core welding method for welding by adjusting the level of the lower electrode wheel according to the present invention,

Figure 8 is a state diagram showing the welding state of the mesh core welder by the mesh seam welding method for welding by adjusting the level of the lower electrode wheel according to the present invention.

<Explanation of symbols for main parts of drawing>

1: Frame 2-1,2-2: Entry clamp 3-1,3-2: Exit clamp

4: trailing strip 5: preceding strip 6: upper electrode wheel 7: lower electrode wheel

8: upper dresser 9: lower dresser 15: guide roll 21: ball screw

22: electric motor 23: reducer 24: guide bush 31: level displacement sensor

32: motor 33: gearbox 34: gearbar

In order to achieve the above object, the present invention comprises the steps of performing the dressing by determining whether the dressing for the electrode wheel (6,7) of the mesh core welder; Setting the theoretical peak level of the lower electrode wheel 7 according to the target thickness and steel type thickness of the welded part when the dressing process for the electrode wheels 6 and 7 is completed; When the theoretical peak level of the lower electrode wheel (7) is set, the displacement sensor (31) moves to the lower electrode surface measurement position to measure the actual peak level of the lower electrode wheel (7); Setting the lower electrode wheel 7 to the theoretical peak level by moving the lower electrode up and down to match the actual peak level of the lower electrode wheel 7 measured by the displacement sensor 31 with the set theoretical peak level. Wow; When the level setting of the lower electrode wheel (7) is completed is provided a mesh core welding method for welding by adjusting the level of the lower electrode wheel, characterized in that consisting of the step of performing welding,

When the dressing process for the electrode wheels 6 and 7 is completed, the step of setting the theoretical peak level of the lower electrode wheel 7 for each target thickness and steel type thickness of the welded part is calculated by the following equation. It provides a mesh core welding method for welding by adjusting the level of the electrode wheel.

t _Goal : Estimated thickness of weld

t _{leading strip} : thickness of the leading strip

t _{trailing strip} : thickness of the trailing strip

y _{Lower electrode wheel highest point} : Set point of lower electrode wheel

y _{Upper surface of lower clamp} : _{Upper surface of} lower clamp

α: The ratio is thicker than the average thickness [(t _{leading strip} + t _{trailing strip} ) / 2] calculated when welded under the welding conditions set according to the type and thickness of the material.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

The present invention considers in advance the thickness of the welded part obtained by welding according to the welding conditions (welding current, welding speed, electrode pressing force, etc.) set according to the steel type and thickness of the strip to be welded before welding. The height is set to a predetermined height, that is, a position lower than the upper surface of the entry-side lower clamps 2-2 and 3-2 by a predetermined height, and then welding is performed.

At this time, the predetermined height is a theoretical peak level value of the lower electrode wheel, which is considered in advance by the following equation depending on the type and thickness of the material.

[Equation 1]

[Equation 2]

Where the _target is the estimated thickness of the welded part considering the set welding conditions, material thickness and steel grade, the _{leading strip} is the thickness of the preceding strip, the _{trailing strip} is the thickness of the trailing strip, and the _{lower electrode wheel highest point} is the lower electrode wheel. The _{upper clamping} value of the lower clamp is the upper height of the lower clamp, and α is the average thickness calculated by welding under the welding conditions set according to the type and thickness of the material [(ｔ _{leading strip} + _{trailing strip} ). / 2] is about 1.2 thicker than the ratio.

That is, in the line, information (steel grade, thickness, width, etc.) about the leading and trailing strips (5, 4) to be welded is input to the control computer 35 in advance, and the welding conditions (welding current, welding speed, pressing force, overlap amount, etc.) ) Will be set.

So when performing the welding operation in a predetermined condition by analyzing the ratio of the average thickness of the thickness of the weld and welding wires trailing strip (5,4) with a statistically store the average value in the database, welding target thickness (t _target) The target thickness t _target is substituted into Equation 2 to calculate the level set value (xy _{lower electrode wheel highest} point) of the highest point of the lower electrode wheel 7.

On the other hand, when the welding operation is completed, it is usually determined by the operator's judgment or by the sensor (not shown) that monitors the surface state of the electrode wheels 6 and 7 to determine the dressing operation of the electrode wheel, and when the dressing is necessary, The surface of the wheel is dressed by a predetermined amount.

When the dressing is completed, the welding information about the trailing strips 5 and 4 to be welded next is transmitted to the welding machine by the control computer, and when the welding condition is set, the target welding thickness t according to the above equations 1 to 2 _{The target} level and the highest level setting value (xy _{lower electrode wheel highest point} ) of the _{lower electrode wheel} 7 are determined.

At this time, if the target welding thickness (t _target ) and the maximum level value of the lower electrode wheel 7 (xxx _{lower electrode wheel highest point} ) are determined, the displacement sensor 31 is set in advance to set the highest level of the lower electrode wheel 7 before welding. ) Is placed on top of the lower electrode wheel.

In addition, when the displacement sensor 31 starts measuring the highest level of the lower electrode wheel 7, the motor 22 is operated by the difference compared to the highest set value of the lower electrode wheel (xy _{lower electrode wheel highest point} ). Match the highest level position of the lower electrode wheel to the set value.

When the highest level position of the lower electrode wheel 7 coincides with the set value (xy _{lower electrode wheel highest point} ), the displacement sensor 31 is retracted to the original position, and then the welding operation is performed together with the welding operation start signal.

As described above, in the present invention, the welded portion is symmetrically formed up and down, and minimizes spatter generation due to local heating, and according to the dressing period or dressing amount of the upper and lower electrode wheels and the type and thickness of the steel plate, the lower electrode wheel By removing the difference in the circumferential speed, it is possible to provide good mash seam welding.

Claims (2)

Performing dressing by determining whether dressing is performed on electrode wheels 6 and 7 of the mesh core welder; Setting the theoretical peak level of the lower electrode wheel 7 according to the target thickness and steel type thickness of the welded part when the dressing process for the electrode wheels 6 and 7 is completed; When the theoretical peak level of the lower electrode wheel 7 is set, the displacement sensor 31 moves to the lower electrode surface measurement position to measure the actual peak level of the lower electrode wheel 7; Setting the lower electrode wheel 7 to the theoretical peak level by moving the lower electrode up and down to match the actual peak level of the lower electrode wheel 7 measured by the displacement sensor 31 with the set theoretical peak level. Wow; When the level setting of the lower electrode wheel (7) is completed, welding is performed by adjusting the level of the lower electrode wheel, characterized in that the welding step. The method of claim 1, When the dressing process for the electrode wheels 6 and 7 is completed, the step of setting the theoretical peak level of the lower electrode wheel 7 for each target thickness and steel type thickness of the welded part is calculated by the following equation. Mesh core welding method for welding by adjusting the level of electrode wheel.

t _Goal : Estimated thickness of weld t _{leading strip} : thickness of the leading strip (5) t _{trailing strip} : thickness of the trailing strip (4) y _{Lower electrode wheel highest point} : Set _{point of} lower electrode wheel 7 y _{Upper surface of lower clamp} : _{Upper surface of} lower clamp α: The ratio is thicker than the average thickness [(t _{leading strip} + t _{trailing strip} ) / 2] calculated when welded under the welding conditions set according to the type and thickness of the material.

Images