JPS581987B2 - Continuous coating method for hot-rolled coil steel sheets - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for coating a steel plate, and in particular to a continuous coating method for shot-blasted hot-rolled coil steel plates.

Conventionally, the steel strips obtained from hot-rolled coils were painted by surface-treating the steel strips by shot blasting, etc., then cutting them into predetermined dimensions, and then applying the necessary paint, such as anti-corrosion paint, by spraying or brushing. It is generally done by coating, etc., and it is applied to some cold-rolled coiled steel sheets such as galvanized steel sheets, etc.
At present, the roll coating method, which is known as a coating method for extremely thin objects, is not used at all.

This is because hot-rolled coils are thick, and the so-called crown phenomenon and warpage of the steel plate that cannot be avoided during hot rolling remain, so the roll does not hit the surface of the steel plate evenly, and as a result, not only does the paint not apply evenly to the flat surface of the steel plate. This is because there were problems such as the inability to freely adjust the coating thickness.

However, with conventional painting methods such as air spray and airless spray, the work efficiency is extremely low because, as mentioned above, hot-rolled coils are shot-blasted and then cut into predetermined dimensions before being painted one by one. Moreover, when spraying the paint, the paint scatters by about 30 to 40 parts, making it uneconomical and resulting in high manufacturing costs.

In addition, since spray painting involves moving the nozzle back and forth over the board surface several times, the paint film becomes thicker in the areas where the spray overlaps, making it impossible to make the paint film uniform. It was difficult to apply it evenly.

Furthermore, since the paint is sprayed with air in the spray method, moisture accumulates in the recesses on the surface of the steel plate, which has a negative effect on the adhesion of the paint.

In addition, the conventional plating and painting method for hot-rolled coil steel sheets is to shot-plast the hot-rolled coil steel sheets, immediately apply rust preventive oil, and then cut the steel sheets when necessary, degrease them, and then plate them. However, in this case, the surface of the shot steel plate has rough irregularities, and it is difficult to remove oil from the dented areas, so oil remains there, and this oiliness becomes an obstacle, and in the case of plating. This had the disadvantage of causing uneven spots, and in the case of painting, it caused the paint film to peel off.

Furthermore, the rust-preventive surface-treated steel sheets that have been mainly used in the past are made of continuous plated steel sheets made of cold-rolled coils, and since these are plated on both sides, they generate hyum gas, which is harmful to the human body, during welding. Or, there may be problems such as sputtering (zinc sparks flying) and electrolytic failure of the steel.
Therefore, there is a drawback that plating must be removed from the edges of one side of the plated steel plate each time.

The present invention has been made in consideration of the various problems mentioned above, and is intended to solve the problem of relatively thick steel sheets that have crowns and warpage that are unavoidable during hot rolling, or unevenness on the surface of steel sheets that appears after shot blasting. A hot-rolled coil that can be applied to a thick hot-rolled steel plate with a completely uniform coating and the thickness of the coating can be freely adjusted, and the width of the coating on the steel plate can also be freely adjusted. The present invention provides a continuous coating method for steel plates.

Hereinafter, an apparatus for carrying out the method of the present invention will be explained.

In the figure, reference numeral 1 indicates a mounting part for mounting a hot-rolled coil 2, and 3 indicates a surface treatment (removal of rust or mill scale, removal of dust, 4 is a shot blasting device 3 for removing attached contaminants such as
This is a roll coating device that coats steel strips that have been surface-treated by.

As shown in FIGS. 2 and 3, this roll coating device 4 includes two coater rolls 5 and two doctor rolls 6.
It has four metering rolls 7 and two cleaning rolls 8.

The coater rolls are made of an elastic rubber material (in this embodiment, the hardness of the rubber of the coater roll is 78°) and are formed into a cylindrical shape, and are rotatable about their respective axes.

Each of these rolls has one coater roll 5 for surface coating of the strip steel on the upper side, and this coater roll 5.
One doctor roll 6 is formed to have the same length as the axial length of the coater roll 5 and supplies paint to the coater roll 5, and left and right doctor rolls 6 are arranged to remove paint from both left and right ends of the outer peripheral surface of the doctor roll 6. A pair of metering rolls 7
(This metering roll 7 can slide in its axial direction) and this metering roll 7
One cleaning roll 8 with a large roll width is disposed to remove paint adhering to the steel strip, and one cleaning roll 8 for painting the back side of the steel strip is arranged on the lower side in the same manner as the upper side. coater roll 5, one doctor roll 6 that supplies paint to this coater roll 5, a pair of left and right metering rolls 7 excluding the paint at both left and right ends of the outer peripheral surface of this doctor roll 6, and this metering roll 6. One cleaning roll 8 for removing paint adhering to the roll 7 is provided respectively.

As shown in the figure, these upper and lower roll groups are in contact with the outer circumferential surfaces of each of the adjacent rolls, and as a result, the coater roll 5 for coating the strip steel
In synchronization with the rotation of the rolls, the other roll groups are also rotated in either the forward or reverse direction.

As shown in FIGS. 4 and 5, the upper roll group is fixed to double-structured roll supporting side plates 10 and 10 erected on both sides of the base 9, but the lower roll group The roll group is controlled by pressure adjustment devices 11 and 11 built into the roll support side plates 10 and 10, respectively (when the handle 12 of this pressure adjustment device is rotated, the shaft 14 is moved up and down by the gear 13, and the spring 15 and the load are The shaft 5a of the coater roll 5 moves up and down via the detection device 16, and the shafts of the other roll groups on the lower side also move up and down in conjunction with the up and down movement of the shaft 5a.

), it is configured to be movable up and down within a predetermined range, so that the pressing rate of the coater roll 5 against the steel strip can be adjusted.

The upper and lower coater rolls 5, 5 also have sprocket wheels 17, 17 at one end of their respective shafts.
are attached and interlocked by a chain 18.

A driving sprocket wheel 19 is further attached to one end of the shaft of the upper coater roll 5, and this driving sprocket wheel 19 and a sprocket attached to the output shaft of a reducer 20 provided on the base 9 side - A chain 22 is interlocked with the wheel 21.

The sprocket wheel 21 of this speed reducer 20 is rotated by a drive motor 24 via a continuously variable transmission 23.

In addition, 25 is a load detector that shows the detected values of the pair of left and right load detectors 16 and 16, 26 is a paint tray for storing paint for coating steel strips, 27 is a solvent tray for storing solvent such as thinner, and 28 is a cleaning tray. A brushing roll for brushing the paint adhered to the outer peripheral surface of the roll 8 and removing the paint together with the solvent is shown.

Further, 29 is a drying device that is disposed on the exit end side of the roll coating device 4 and can continuously dry the paint applied by the coating device 4, and 30 is a drying device for winding the coated steel strip. It is a device.

Next, a coating method for coating a hot rolled coil steel plate using the above-mentioned apparatus will be explained.

First, with the left and right pressure adjustment handles 12, the pressure rate of the upper and lower coater rolls on the steel strip to be coated is set to a predetermined pressure value, and the drive motor 24 is driven to control the upper and lower rolls. Rotate the group.

Next, the outer circumferential end of the hot rolled coil 2 mounted on the mounting section 1 is inserted from the inlet end of the shot blasting device 3 via the winding devices P1 and P2.

Then, the hot-rolled coil 2 is sequentially released from its coiled state starting from its outer circumferential end and becomes a steel strip.The shot blasting device 3 performs surface treatment (rust removal on both the front and back surfaces) of the steel strip. However, at this time, an active adsorption force is generated on the shot-blasted surface of the steel strip, which has the effect of increasing the adsorption force of the paint.

The surface-treated steel strip advances from the outlet side of the shot blasting device 3 to the inlet side of the roll coating device 4 (the direction of travel is indicated by arrow A in the figure) and is transferred to the roll coating device 4.
between the coater rolls above.

At this time, the upper and lower coater rolls 5, 5 coat both the front and back sides of the steel strip, but as mentioned above, the upper and lower coater rolls 5, 5 are made of an elastic rubber material, and their surfaces are deformed. Because it is flexible, it can be deformed freely against the crowns and warps of the steel strip itself, as well as the irregularities on the surface of the strip that occur during shot blasting, and the coating film T applied to the steel strip can be applied uniformly. (See Figure 6)
.

Here, paint is supplied to the upper and lower coater rolls 5, 5,
The functions of the other rolls and groups for adjusting the coating width of the steel strip will be explained, but here, in order to simplify the explanation, only the upper roll group will be explained.

First, when the coater roll 5 rotates in the direction shown by the arrow in FIG.
is rotated in the opposite direction to that of the coater roll 5, and at this time, the paint adhering to the outer peripheral surface of the doctor roll 6 is sequentially applied to the outer peripheral surface of the coater roll 5 and transferred.

Next, at the same time as the doctor roll 6 rotates, the metering roll 7 rotates in the direction of the arrow in the figure.
The paint on both left and right end portions of the outer circumferential surface of the metering roll 7 is sequentially applied to the outer circumferential surface of the metering roll 7 and transferred, thereby coating a predetermined width of the steel strip inserted between the upper and lower coater rolls.

Next, at the same time as the metering roll 7 rotates, the cleaning roll 8 rotates in the direction of the arrow in the figure, and at this time, the paint adhering to the outer circumference of the metering roll 7 is sequentially applied to the outer circumference of the cleaning roll 8 and transferred. It will be done.

The paint adhering to the outer circumferential surface of the cleaning roll 8 is removed by the solvent in the solvent tray installed at the lower part of the cleaning roll 8, and is further brushed by the brushing roll 28 to completely remove the paint.

By causing each roll group to perform a series of operations in this manner, a predetermined width of continuous coating is performed on both the front and back surfaces of the steel strip inserted between the upper and lower coater rolls 5,5.

The steel strip coated to a predetermined width and thickness by the roll coating device 4 has its paint dried by the drying device 29, and is sequentially wound up by the winding device 30.

Note that by moving the metering roll 7 in its axial direction and adjusting the contact portion with the outer circumferential surface of the doctor roll 6, the coating width on the steel strip can be changed freely.

In the embodiment, the steel strip coming out of the outlet end of the dryer 29 is sequentially wound up by the winding device 30, but a cutter such as a rotary shear may be provided at the outlet end of the dryer 29. The steel strip coming out of the outlet end of the dryer 29 may be continuously cut into predetermined size units.

Furthermore, it goes without saying that the present invention is not limited to short coil steel plates, and can also be applied to steel plates cut into predetermined dimensions in the same manner as described above.

In addition, in the examples, we have mainly described the method of painting both the front and back sides of the steel strip, but if necessary, when painting either one side, for example, when painting the front side of the steel strip, the upper and lower doctor rolls can be used. This can be easily carried out by removing in advance the amount of paint in the paint trays of the side doctor roll from among the paint in the paint trays installed at the bottom.

As described above, in the continuous coating method for hot-rolled coil steel sheets according to the present invention, crowns and warps on the hot-rolled coil steel sheets themselves,
Alternatively, it was impossible to perform continuous coating on irregularities on the surface of a steel plate that occur during shot blasting, but with the present invention, this can be done easily. It has the advantage that by adjusting the pressure rate of the rolls, it is possible to freely apply coatings to a minimum coating thickness of about 1 micron, which was almost impossible with conventional spray methods.

In addition, when supplying paint to the upper and lower coater rolls, the coating width of the steel strip can be freely adjusted by adjusting the width of the paint delivered to the outer circumferential surface of the coater rolls. There is no need to remove the coating each time.

Furthermore, in the present invention, since the roll coating device is placed next to the shot blasting device to perform continuous coating immediately after shot blasting, the active adsorption force generated during shot blasting (this active adsorption force is maintained for a certain period of time) ) can be used effectively,
This not only makes the adsorption power of the paint even stronger, resulting in an extremely superior rust prevention effect, but also simplifies the work process as there is no need to apply rust preventive oil or degrease the rust preventive oil. It has various excellent effects.

[Brief explanation of drawings]

The figure shows an apparatus that implements the method of the present invention. Figure 1 is a schematic diagram of a coating line that continuously coats hot-rolled coiled steel sheets, and Figure 2 is a diagram showing the upper and lower rolls of a roll coating device. FIG. 3 is a side view showing the arrangement of the groups; FIG. 3 is a plan view showing the arrangement of the upper roll group; FIGS.
The figures are a front view and a side view showing a schematic configuration of the roll coating device, and FIG. 6 is a partially enlarged view showing a state in which the upper and lower coater rolls are elastically deformed with respect to the surface of a steel plate. 2... Hot rolled coil, 3... Shot blasting device, 4... Roll coating device, 5...
... Coater roll, 6 ... Doctor roll, 7 ... Metering roll, 8 ...
Cleaning roll, 11...pressure adjustment device,
16... Load detection device, 27... Solvent saucer, 28... Brushing roll, 29...
...Drying device.

Claims (1)

[Claims] 1 Next to the shot blasting device, cylindrical coater rolls made of an elastic rubber material are arranged one above the other, and the pressure application rate between the upper and lower coater rolls is variable, and a detection device is provided to detect the pressure application ratio. and a roll coating device further provided with a paint supply device for supplying paint to the upper and lower coater rolls and adjusting the width of the paint at both ends of the outer peripheral surfaces of the upper and lower coater rolls, and a drying device. The hot-rolled coiled steel sheet whose surface has been surface-treated by the shot blasting device is passed between the coater rolls of the roll coating device and coated with paint by the rotation of the rolls, and the coated steel sheet is sent to the drying device to be dried. A continuous coating method for hot-rolled coil steel sheets, characterized by finishing the hot-rolled coil steel sheets.