JPS6051864B2 - Steel plate coating method and equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method and apparatus for coating steel plates.

Conventionally, when painting a steel plate, for example, when manufacturing a colored galvanized steel plate by applying a colored paint to a galvanized iron plate,
Degreasing treatment → chemical conversion treatment → undercoat painting → baking first top coat →
It was common to perform each process on a continuous line using continuous painting equipment in which equipment for each process such as baking was arranged in series.
However, this method requires a large amount of equipment and is suitable for mass production, so it is not flexible.
It was not suitable for painting many types of small rods. The present invention has been made in view of these circumstances, and an object of the present invention is to provide a coating method that uses inexpensive equipment and is highly efficient. There is a particular thing.

That is, an object of the present invention is to perform a series of painting process operations on a steel plate placed in a heating furnace by using a degreasing treatment device and/or a chemical conversion treatment device, a painting device, and a baking device installed in the heating furnace. This is accomplished by performing the steps in a batchwise manner in a heating furnace.

The present invention will be explained based on examples shown in the accompanying drawings.

The accompanying drawing is a schematic diagram showing an example of coating equipment used in the method of the present invention. 1 is a heating furnace used for annealing, and is equipped with a heating device 2 such as a burner, an inner cover 3, and a seal 4 such as a sand seal.

Since annealing is usually performed in a reducing atmosphere gas, nitrogen,
Atmospheric gas such as argon or ammonia is supplied into the inner cover 3 from the gas inlet 5. A circulation fan 6 is provided at the base of the heating furnace 1 to circulate atmospheric gas within the inner cover 3 to make the temperature within the furnace 1 uniform.
Reference numeral 7 is a differential user, which functions to diffuse atmospheric gas within the furnace 1.

The heating furnace 1 used in the present invention further includes a treatment liquid application device as coating equipment, for example, a first spray device 8 for injecting a chemical conversion treatment liquid toward the upper surface of the loose coil 17, and a second spray device for spraying paint. 9, as well as a conduit 10 for waste liquid discharge.

The first and second spray devices 8 and 9 are connected to a chemical conversion liquid tank 13 and a paint tank 14 installed outside the furnace 1 via vibrators 11 and 12, respectively, and a pump 15
, 16 are supplied to the spray devices 8, 9 via vibrators 11, 12, respectively. The conduit 10 is for discharging each waste liquid after chemical conversion treatment and paint application to the outside of the furnace 1.
Next, a method of coating a copper plate according to the present invention will be explained.

The steel plate coil 17 that has been annealed in the annealing furnace 1 is then subjected to the following series of coating operations in a batch manner in the annealing furnace 1. The copper plate coil 17 is placed on the base in the furnace 1 in a loose state with gaps formed between the copper plates so that the surface of the steel plate can be subjected to the treatments in each step.
In terms of treatment effects (adhesiveness of each liquid sprayed in each step to the steel plate), it is desirable that the gap between the steel plates be about 2 to 5 Tr$t. Although the tight coil loosening operation can be performed after the annealing process and before the painting process, it is preferable to perform the loosening operation before the annealing process, taking into consideration the nature of the work.
(1) Surface preparation Normally, the surface of a steel plate has rust, scale, a large amount of oil, dirt, etc. attached to it, which greatly affects the rust prevention properties after painting and the finish of the paint.

Therefore, as the first step in the coating process, the substrate is prepared to remove these deposits and improve the quality of the substrate. The treatment process for substrate preparation varies depending on the purpose of painting, product usage conditions, shape, etc.3, but may include degreasing treatment and/or chemical conversion treatment,
Furthermore, other processing steps are selected as necessary. For example, when performing a certain substrate preparation from a degreasing treatment and a chemical conversion treatment step, first, a reducing atmospheric gas such as H2,
Gas 3. N2, H2O gas, etc. Gas is blown into the furnace 1 through the inlet 5 and circulated through the furnace 1 by the gas circulation fan 6 and differential user 7 to remove oils and fats adhering to the surface of the steel plate. This degreasing process is usually 300 to 500
It is carried out at a furnace temperature of 4C, preferably from 350 to 450C. The processing time is 20 to 5 times, preferably 25 to 4 times. Next, the pump 15 is operated to pump up the chemical conversion treatment liquid in the tank 13, and the chemical conversion treatment liquid is supplied to the first spray device 8 via the vibrator 11 and sprayed onto the loose coil 17. As the chemical conversion treatment solution, for example, an aqueous phosphate solution such as manganese phosphate or zinc phosphate is used. By injecting the chemical conversion treatment liquid to the loose coil 17 in this manner, the chemical conversion treatment liquid is reacted with the steel sheet base material to form a film on the steel sheet surface (chemical conversion treatment). This film provides corrosion resistance to the steel plate and also forms the base for painting. The time required for the reaction with the steel plate substrate is determined by the temperature, the concentration of the chemical conversion treatment liquid, and other conditions, so these conditions must be appropriately selected in order to increase the chemical reaction rate of the chemical conversion treatment. Among the injected chemical conversion treatment liquids, those other than those that adhere to the copper plate and cause a chemical reaction are discharged to the outside of the furnace 1 through the conduit 10. Alternatively, it is also possible to temporarily store the injected chemical conversion treatment liquid in the heating furnace 1 and immerse the coil 17 in the chemical conversion treatment liquid. This method is advantageous in that the chemical conversion solution is applied more uniformly. (2) Undercoat Undercoat is a process in which an undercoat is applied to the base surface after the above-mentioned base preparation has been completed in order to improve the performance and quality of the topcoat film, but the condition of the base surface, the quality required for the product, etc. It can be omitted.

The primer coating is performed in substantially the same manner as the coating process described in detail below. Specific conditions such as the thickness of the coating film to be formed, the concentration of the coating material used, and the spraying time are appropriately selected depending on the purpose. The steel plate coated with an undercoat is baked in the same manner as the baking process described below (Fig. 1 Baking). In the case of synchronized copper plate manufacturing, which will be described later, coating and baking of Dachromat solution is performed as an undercoating process. 3) Painting (top coat) When applying the undercoat, a further coat of paint is applied to the coated surface after the first baking step, and a final coat is applied.

If the undercoating process is omitted, the paint is applied to the base surface of the steel plate after the base preparation process. That is, the pump 16 is driven to draw up the paint in the tank 14, the paint is supplied to the second spray device 9 via the vibrator 12, and the paint is sprayed from the spray device 9 onto the coil 17 to form a coating film on the surface of the steel plate. Form. As the paint used, thermosetting acrylic paint is suitable. In this coating process, as in the above chemical conversion treatment, the paint may be stored in the heating furnace 1 and the coil 17 may be immersed in the paint. The waste liquid is discharged outside the furnace 1 via a conduit 10. (4) After applying the baking paint, use a burner to raise the temperature inside the furnace 1 to a maximum of 500.
Baking is preferably carried out at a temperature of 300 to 400'C.

The baking time is 5 to 1 powder, preferably 6 to 1 powder. The steel plate is painted in the manner described above. As described above, the present invention is particularly effective when performing the series of painting steps described above with the coil 17 left in the annealing furnace 1 after the annealing treatment, but it is possible to carry the steel sheet from outside the annealing furnace 1. When installing steel plates, the same procedure can be used to paint the steel plate.

According to the method of the present invention, the coating processing speed is greatly improved.

For example, thickness 0.8TI$L1 width 10007707!
When painting a cold-rolled steel plate weighing 45 tons, first loosen the tight coil and adjust the gap between the steel plates to about 2Tf$L, and then insert the coil into the heating furnace 1 having the above-described configuration. After that, paint is applied using the following steps. (1) Degreasing treatment: Blow H2, N2, and H2O gas into the furnace 1. Temperature: 400°C Processing time: 3Cy): 1-(
2) Chemical conversion treatment: Spray phosphate aqueous solution.
Processing time: 2 minutes (3) Paint application: Spray thermosetting acrylic paint.

Processing time: 2 minutes (4) Baking: Baking in heating furnace 1.

Temperature: 300℃ Baking time: 6 minutes In this case, it will take 1 minute to loosen the coil and 1 minute to make other setups.
A total of 6 minutes of time is required to apply the coating according to the method of the present invention.

Converting this to the amount of steel plate coating processed per hour is 60 tI.
It becomes hr. On the other hand, in the case of the conventional method using a continuous line, it is generally about 30 tIhr, so it can be seen that the coating processing speed is significantly improved by the present invention, and coating can be performed with high efficiency. In the above description, the case where the present invention is applied to the production of colored steel sheets has been described, but the present invention is not limited to this, and can also be suitably used for the production of synchro steel plates. To be more specific, after the above-mentioned base preparation such as degreasing, the steel plate coil 17 in the heating furnace 1 is coated with a Dacromat solution (based on chromic acid, a specific organic compound and zinc to improve rust prevention and weldability). An aqueous solution containing a zinc-rich primer) is applied using a spray device 8 and baked in a heating furnace 1.Furthermore, a zinc chromat solution (a special zinc-rich primer) is applied on top of this using a spray device 9 and baked in a heating furnace 1. Synchro steel plates are manufactured. Products coated with only Dacromat solution and baked are also useful as Dacro steel plates. As described above, according to the present invention, a series of copper plate coating steps are performed batchwise in a heating furnace, so that a wide variety of products with small rods can be coated with high efficiency. Furthermore, according to the present invention, by using the heating furnace equipment and replenishing some of the necessary equipment in the heating furnace, the saw ream painting process is performed in the heating furnace, so that the equipment for each of these processes can be There is no need for large-scale continuous painting equipment, and the number of equipment can be greatly reduced.

[Brief explanation of drawings]

The figure is a schematic explanatory diagram showing an example of coating equipment for carrying out the method of the present invention. No. 1: Heating furnace, 2: Burner, 3
...Inner cover, 8...First spray device, 9...Second spray device, 10...
... Waste liquid discharge conduit, 13 ... Chemical treatment liquid tank, 14 ... Paint tank, 17 ◆● Coil.

Claims (1)

[Claims] 1. A steel plate coil is placed in a heating furnace, and in a loose state, the steel plate is subjected to surface conditioning treatment, paint application, and baking, and these A steel plate coating method characterized by performing a series of treatments in a batch manner. 2. A steel plate coating apparatus, characterized in that a spray device for applying a treatment liquid to the steel plate is arranged in a furnace in which a steel plate coil is heated, and a discharge port for discharging the treatment liquid is further provided.