JP4370628B2 - Thickening method for lap weld joints - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a process line for continuously producing metal plates such as steel plates in a lap welded joint portion in which a rear end portion of a preceding metal plate and a front end portion of a subsequent metal plate are overlapped and welded. The present invention relates to a method for reducing the thickness of a lap weld joint for reducing the thickness.
[0002]
[Prior art]
For example, a mash seam welding apparatus is known as a facility for welding and connecting a preceding metal plate and a succeeding metal plate in a process line for continuously producing metal plates.
The mash seam welding device is a method in which the ends of metal plates are overlapped and welded by a rotary electrode, and a lap weld joint portion (also referred to as a swaging roll) is welded to the overlap welded portion. It is an apparatus that reduces the wall thickness by applying pressure and reducing the thickness so that it is substantially equal to the thickness of the portion other than the joint.
[0003]
FIG. 1 is a schematic diagram for explaining a method of reducing the thickness of a lap weld joint applied to the mash seam welding apparatus.
That is, the overlapping portion of the preceding metal plate 1a and the succeeding metal plate 1b is pressure welded using a pair of upper and lower welding electrodes 2, and then using a pair of upper and lower finish rolls 3 connected to the rear of the welding electrode 2. Pressurize the lap weld joint to reduce the thickness. Here, 2a and 3a are respective pressure cylinders.
[0004]
In the apparatus illustrated in FIG. 1, the welding operation of the lap weld joint and the pressure thinning operation can be performed simultaneously. Each device is disposed on a common C-shaped frame (carriage) 10. Here, as shown in FIG. 1, it is most efficient to perform the welding operation and the pressurization thinning operation at the same time, but it is natural that they may be performed separately.
[0005]
In this mash seam welding apparatus, the welding electrode 2 and the finish roll 3 are pressurized at a predetermined pressure, and perform a welding operation and a thickness reducing operation while rotating respectively.
However, because the push roll 3 performs the pressurizing and thinning operation, it is necessary to increase the applied pressure, so that the frictional force received by the roll bearing becomes too large and can rotate smoothly. In other words, there was a problem that the friction between the lap weld joint portion and the roll that was being pressurized increased and the lap weld joint portion was damaged.
[0006]
Therefore, conventionally, a finish roll is set as a drive type, and the roll is driven to give rotation.
In order to perform a stable thickness reduction operation without damaging the lap weld joint, it is already known that it is preferable to match the peripheral speed of the rotating roll and the moving speed of the roll. (See JP-A-3-57567).
[0007]
That is, if the peripheral speed and the moving speed of the finish roll are inconsistent, troubles such as tearing of plates at both ends of the lap weld joint and wrinkles generated along the lap weld joint will occur.
For example, in Japanese Patent Application Laid-Open No. 5-185241, in order to match the peripheral speed and the moving speed of the finish roll, the peripheral speed and the moving speed are detected using a sensor, and the roll drive is controlled using a control device. In addition, in order to make the operating condition of the hydraulic motor that drives the finish roll constant, an oil temperature control device is added to the hydraulic circuit to keep the temperature of the hydraulic oil constant so that the hydraulic operation is stabilized. Is disclosed.
[0008]
Here, the thickness of the lap weld joint is approximately twice the original metal plate thickness (200%), but by pressing the lap weld joint with a polish roll, about 130-140% The thickness is reduced to a thickness of 5 mm to maintain the plate-passability in the subsequent process.
[0009]
[Problems to be solved by the invention]
However, it is not easy to actually match the peripheral speed and the moving speed of the finish roll, and in particular, high precision control is required in the hydraulic / pneumatic drive system normally applied in mash seam welding equipment. If it is to be realized, the equipment becomes complicated and the amount of capital investment becomes extremely large. For this reason, it is impossible to take advantage of the simplicity that is the advantage of the oil-pneumatic drive system.
[0010]
Even if the equipment is complicated and a control system is provided, a satisfactory control result cannot always be obtained.
For example, the pressurization load of the finish roll is slightly reduced at the end portion of the lap weld joint, so that the peripheral speed and the moving speed are shifted, and the peripheral speed is increased and a pulling force is applied to the plate. In order to perform such control to correct the pulling force, even if feedback control is performed by detecting a change in the roll peripheral speed with the above-described sensor, the control is not in time. In particular, in the case of a thin metal plate having a plate thickness of 0.02 mm or less, the occurrence of plate tearing or the like at the terminal end of the lap weld joint is extremely increased.
[0011]
On the other hand, when a simple hydraulic / pneumatic drive system is applied and the speed of the hydraulic motor that simply drives the roll of the finish roll is set so that the peripheral speed and the moving speed are set to constant values, the metal to be processed The peripheral speed changes depending on the thickness of the plate, and the motor speed varies seasonally. Therefore, the peripheral speed and the moving speed cannot be completely matched.
[0012]
For this reason, conventionally, operation is allowed even if the peripheral speed and the moving speed of the finish roll are deviated to some extent, and the operation is allowed with a certain degree of board tearing (such as board tearing) and wrinkles. It was. However, since the degree of occurrence is slight, it is decided to use it as it is in the subsequent process. However, the occurrence of about 2% plate breakage during the line processing could not be avoided.
[0013]
The above problems are especially likely to occur when the roll pressure of the finish roll is high, or when the lap weld joint is extremely thick or extremely thin, and can be avoided only by adjusting the roll peripheral speed. It is very difficult to do.
In particular, in the steady portion excluding the start end and the end portion of the lap weld joint, even if the peripheral speed and the moving speed of the finish roll are deviated to some extent, the deviation can be kept within a certain allowable range. However, there are many cases where the deviation becomes large at the unsteady portion where the finish roll rolls over the starting end of the lap weld joint and immediately before the finish roll leaves the end portion of the lap weld joint. It tends to occur frequently.
[0014]
In general, at the starting end of the lap weld joint, the finish roll bites into the lap weld joint, and therefore the roll peripheral speed tends to be slow. On the other hand, at the end portion, the load on the finish roll is lightened due to the slippage of the plate, so the roll peripheral speed tends to increase.
Here, based on FIG. 2, the situation of troubles such as wrinkle generation when the peripheral speed and the moving speed of the finish roll are different will be described. FIG. 2 shows a case where the lap weld joint portion 4 in which the overlapping portions of the metal plates 1a and 1b are welded is pressed and reduced in thickness while being moved in the carriage traveling direction 5 by a not-shown polish roll. Here, (a) represents the situation in which the peripheral speed of the plastics Danish rolls wrinkles 6a occurs faster than the moving speed, schematic for sheet drawing tear portion 7a that occurs just before leaving the welded joint portion Plastic Danish rolls superimposed Is shown. In this case, almost no wrinkles are generated when the finish roll rides on the lap weld joint.
[0015]
Note that tearing refers to a phenomenon in which the end of the plate is bent and torn when the plate is pulled (to the OP side in the case of the figure) when the finish roll gets on and off.
On the other hand, (b) shows a situation where wrinkles 6b (the direction is almost opposite to the wrinkles 6a) occurs when the peripheral speed of the finish roll is slower than the moving speed, and the finish roll tries to ride on the lap weld joint. A plate pressing tearing portion 7b generated by pressing the plate at the time is schematically shown.
[0016]
Here, pushing tearing refers to a phenomenon in which the plate roll is pushed and bent without being able to ride on the plate due to insufficient peripheral speed. At this time, conspicuous wrinkles are likely to occur due to tearing, particularly at the board end on the boarding side (7c), but this part is also referred to as a “worm”.
An object of the present invention is to prevent troubles such as wrinkles occurring in the unsteady part of the start and end parts of the lap weld joint as described above, and to enable stable operation in the subsequent process. The present invention provides a method for reducing the thickness of a lap weld joint suitable for driving a punish roll only with a simple hydraulic / pneumatic drive system that does not have a complicated control system and reducing the thickness of a lap weld joint. .
[0017]
[Means for Solving the Problems]
The present invention relates to a method for reducing the thickness of a lap weld joint part in which a lap weld joint part of a metal plate is pressed and reduced in thickness while moving a roll drive type polish roll. when run on the parts are the peripheral speed of the plastics Danish rolls leave faster than the moving speed, when lowering ride at least the plug Danish rolls lap welded joint portion, the movement the peripheral speed of the plastics Danish rolls The above-mentioned problem has been solved by a method of reducing the thickness of a lap weld joint characterized in that it is slower than the speed.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, when the finish roll rides on the lap weld joint, the peripheral speed of the finish roll is set to be faster than the moving speed, and immediately before the finish roll leaves the lap weld joint. The peripheral speed of the finish roll is set to be slower than the moving speed.
[0019]
Here, in the above case, the peripheral speed is preferably set to be about 2 to 5% faster or slower than the moving speed, and is most preferably set to 3% as a representative value.
Moreover, it is preferable that the section set by varying the peripheral speed and the moving speed at the start end and the end of the lap weld joint is about 50 to 100 mm from the start and end, respectively, It is preferable to set the circumferential speed and the moving speed substantially equal.
[0020]
Also, with the center portion of the lap weld joint as the boundary, the peripheral speed is set to be faster than the moving speed on the start end side, and the peripheral speed is set to be slower than the moving speed on the terminal end side. Anyway.
As described above, in the present invention, a complicated and expensive control system such as feedback control using a large number of sensors is unnecessary, and the peripheral speed and moving speed of the finish roll are matched with the position of the lap weld joint of the finish roll. It is possible to realize the method of the present invention by simply setting.
[0021]
【Example】
The present invention was applied to a continuous skin pass mill (CAPL), which is a process line for continuously treating cold-rolled steel sheets, particularly temper rolled materials used for tin plate.
After the front and rear ends of the cold-rolled steel sheet were welded, the lap weld joint was pressurized with a punish roll, and the thickness reduction treatment was carried out by the method of the present invention (example of the present invention). Here, the pressurizing force of the finish roll is 2500 kgf. In the example of the present invention, the peripheral speed of the finish roll was set so as to increase by 3% at the start end of the lap weld joint and 3% at the end of the lap weld joint with respect to the moving speed.
[0022]
In addition, the section set so that the peripheral speed and the moving speed are different is set as a section of 100 mm from the start end and the end.
On the other hand, for comparison, as a conventional example, an operation was performed in the case where the peripheral speed and the moving speed of the finish roll were always set to be equal.
As a result, in the operation of the conventional example, wrinkles were observed at the start and end portions of the lap weld joint, and about 2% of the plate fracture occurred in the subsequent process. No plate breakage occurred.
[0023]
In this example, the moving speed of the finish roll is set and the peripheral speed is changed according to the moving speed. However, the present invention is not limited to this method, and the peripheral speed is set. The moving speed may be changed according to the peripheral speed. However, since the movement speed can be changed appropriately depending on the characteristics and thickness of the plate, the operation can be stabilized by changing the peripheral speed in accordance with the movement speed.
[0024]
【The invention's effect】
According to the present invention, the generation of wrinkles in the lap weld joint can be eliminated without a large capital investment, and the occurrence of plate breakage in the subsequent process can be completely eliminated.
[Brief description of the drawings]
FIG. 1 is a schematic view for explaining a method of reducing the thickness of a lap weld joint.
FIG. 2 is a plan view for explaining the occurrence of wrinkles in the vicinity of a lap weld joint.
[Explanation of symbols]
1a Metal plate (preceding metal plate)
1b Metal plate (following metal plate)
2 Welding electrode
2a Welding electrode pressurization cylinder 3 Plane roll
3a Pressurized roll cylinder 4 Lap weld joint 5 Carriage direction
6a, 6b wrinkles
7a Board tearing part
7b Board presser
7c weevil
10 C-type frame (carriage)

Claims (1)

It is a method of reducing the thickness of a lap weld joint that pressurizes and reduces the thickness of a lap weld joint of a metal plate while moving a roll-driven planar roll,
When rides at least in the welded joint portion Plastic Danish rolls overlapped, leave the peripheral speed of the plastics Danish rolls than the moving speed, when lowering ride at least the welded joint portion Plastic Danish rolls overlapped, A method for reducing the thickness of a lap weld joint, characterized in that the peripheral speed of the finish roll is set slower than its moving speed.

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