JP3173913U - Automatic painting production line for anti-corrosion coating on large steel pipes - Google Patents

Abstract

An automatic coating production line for an anticorrosion coating for a large steel pipe, which uses a paint having a high solid content, has high coating efficiency, reduces environmental pollution, and has good impact resistance performance.
SOLUTION: A supply mechanism 1 for rotating and moving a steel pipe 8 is provided, and a dehumidifying / degreasing machine 2 for removing oil and water on the surface of the steel pipe and an automatic for removing a rust film and an oxide film on the surface of the steel pipe in order. A shot blasting machine 3, a preheating chamber 4 for preheating a steel pipe, a spray coating and a solidifying unit are arranged. In this unit, the spray coating chamber 5, the coating film solidifying chamber 6, and the cooling chamber 7 are arranged in order.
[Selection] Figure 1

Description

  The present invention relates to a steel pipe anticorrosion treatment method and its production line, and more particularly to a kind of automatic coating method for large steel pipes and its production line.

  Large steel pipes generally have a diameter of 0.5 m to 2.4 m and a length of 12 m to 90 m, and are made of steel. In recent years, with the rapid development of China's domestic economy, more and more large steel pipes are used in harbors, docks, ship engineering and urban engineering. In order to effectively suppress the corrosion of the large steel pipe, extend the service life of the large steel pipe, and ensure the safe operation of the infrastructure, it is necessary to treat the surface of the large steel pipe with an anticorrosive agent. The most commonly used anticorrosion treatment is to apply an anticorrosion paint on the surface of the steel pipe. Currently, there are three main methods of applying anticorrosion paint on the surface of large steel pipes in China and other countries. That is, manual painting, melt-baked epoxy (FBE) coating and three-layer polyethylene coating (3LPE).

Here, in the manual painting method, a solvent paint is mainly applied on a large steel pipe. That is, first, shot blasting is performed manually or mechanically on a steel pipe, and then paint is applied on the surface of the steel pipe by manual roll coating or spray coating. In the above-described manual painting, the steel pipe can be treated with an anticorrosive paint, but this method has some disadvantages listed below.
(1) Since the organic solvent content in the paint is relatively high, many organic solvents volatilize during the coating drying process, which not only pollutes the environment but also deteriorates the working environment. This can increase the severity of labor for workers and cause human health problems.
(2) At the same time, when manually painting, the large steel pipe cannot be rotated on site, and the viscosity of the selected paint cannot be sufficiently high, and the organic solvent content in the paint is usually 15 % Or more, which results in a non-uniform phenomenon that hangs down after painting and where the upper side is thin and the lower side is thick, thereby greatly reducing the overall anticorrosion performance of the coating on the steel pipe.
(3) The manual painting of large steel pipes is usually applied in an open indoor or outdoor environment, and as a result of restrictions on the working environment and weather conditions, the time of the painting work depends on the weather. Therefore, the quality, progress and efficiency of large steel pipe painting work cannot be guaranteed. At the same time, after applying the paint, the coating solidifies in a natural environment, spending a long time for solidification, and thus occupying a large work site.

  On the other hand, melt-baked epoxy coating is automatically performed on a mechanical production line. As the large steel tube advances in a helical fashion in the drive system, the shot blasting machine removes rust on the surface of the steel tube, and then the steel tube is heated to a temperature by medium frequency induction. Then, the epoxy resin powder is quickly applied onto the surface of the steel pipe by electrostatic coating spray. As soon as the epoxy powder touches the hot steel pipe, it becomes a coating film and adheres to the surface of the steel pipe. Finally, the coating layer is rapidly solidified by rapid water cooling.

  Compared to manual painting, melt-baked epoxy painting has clearly increased the degree of automation, and the painting and solidification of the coating is unaffected by the surrounding environment and the weather, resulting in reduced human labor And the efficiency is relatively high. However, it is rarely applied in other countries as a single coating system. It is very large in temperature change, mainly in the coating process. On the other hand, the steel pipe and the coating layer have different expansion coefficients. Therefore, the internal stress of the coating layer on the steel pipe becomes high, and the coating layer is easily damaged under an external force. If the coating layer breaks, it is very difficult to repair in the same way at the construction site.

  On the other hand, the three-layer polyethylene coating line is mainly used in an anticorrosion coating line for steel pipes to be buried underground. Most steel pipes processed by this method have a length of about 10 meters, and this method cannot be applied to longer steel pipes. Therefore, three-layer polyethylene coating cannot be applied in rust-preventing coatings on large steel pipes, and this three-layer polyethylene coating is hardly seen in harbors, docks, marine engineering and urban engineering.

Currently, several production lines for large steel pipes are disclosed in Chinese publications CN1673604A, CN16772809A and CN11222772C. In these documents, a primer obtained by adding a primer and tape winding, or a primer using PE as a coating material is disclosed. However, few automatic coating production lines using paints with a high solid content have been reported.
Chinese Patent Publication CN1673604A Chinese Patent Publication CN16772809A Chinese Patent Publication CN1122772C

  The first object of the present invention is to provide an automatic coating method for an anticorrosion coating on a large steel pipe using a paint having a high solid content, having high coating efficiency, reduced environmental pollution, and good impact resistance performance. It is in.

  The second object of the present invention is to provide an automatic coating production line for an anticorrosion coating for large steel pipes using a paint having a high solid content, having high coating efficiency, reduced environmental pollution, and good impact resistance performance. There is.

  In order to achieve the first object, the automatic coating method of the anticorrosion coating on the large steel pipe has the following steps.

  In step 1, a steel pipe is arranged in a pipe supply mechanism, and the pipe supply mechanism is started. First, the steel pipe is passed through a dehumidifying and degreasing machine to remove oil and water on the surface of the steel pipe.

  In step 2, after removing oil and water and water, put the steel pipe into an automatic shot blasting machine to remove the rust and oxide film on the surface of the steel pipe, and request before spraying the paint on the surface of the steel pipe Corresponding to cleanliness and surface roughness.

  In step 3, the steel pipe is put into a preheating chamber, and the temperature of replacement waiting for painting is heated to the first heating temperature. The value of this 1st heating temperature is the temperature range which subtracted 40 to 20 degreeC from the solidification temperature value of the coating material to be used.

  In Step 4, after heating, the steel pipe is put into a spray coating chamber. The spray paint machine sprays a second temperature paint onto the surface of the steel pipe. 2nd temperature is the temperature range which subtracted 40 to 20 degreeC from the value of the solidification temperature of the coating material to be used.

  In step 5, the steel pipe coated with the paint is put into the coating film solidification chamber. A hot air circulation system is located in the coating solidification chamber, supplying hot air to heat the steel pipe to the solidification temperature of the paint used.

  In step 6, the steel pipe is placed in a cooling chamber that rapidly cools. The steel pipe can be cooled by air cooling, water cooling or other cooling methods. In the case of the air cooling, natural wind or cooling air can be used.

  In Step 7, when it is necessary to paint the cooled steel pipe with a multilayer coating, the steel pipe is put into the next spray painting / solidifying unit. The next spray coating / coagulation unit is composed of a spray coating chamber, a coating film coagulation chamber, and a cooling chamber in order, and repeats step 4, step 5 and step 6 until all the layers are coated.

  In the present invention, both the value of the first temperature in the preheating chamber, which is the preheating temperature of the steel pipe, and the value of the second temperature of the spray paint correspond to the solidification temperature of the selected paint. Therefore, the steel pipe and the coating can be heated synchronously, the coating film can be rapidly solidified, and the solidification time of the coating can be greatly shortened.

  In order to further reduce the environmental pollution caused by solvent volatilization in the paint and reduce the number of pinholes in the coating, the solvent content of the paint can be less than 10%.

  Preferably, by adopting a system in which hot air is circulated and heated in the coating film coagulation chamber, the cost can be further reduced, the operation can be made safe, and the solidification environment of the coating layer can be improved.

  Preferably, the spray coater can be a high pressure airless spray coater, and the time from when the paint enters the high pressure airless spray coater until the paint is sprayed can be limited to 3 minutes. In a high-pressure airless spray coating machine, the temperature at which the paint is sprayed, the time for mixing the curing agent and the paint, and the time between the heating of the paint and the spraying of the paint can be easily controlled.

  In order to achieve the second objective, an automatic painting production line of a large steel pipe anticorrosive coating has a supply mechanism, a dehumidifying and degreasing machine, an automatic shot blasting machine, and a preheating chamber for preheating (heating) the steel pipe. . The supply mechanism rotates the steel pipe and moves the steel pipe horizontally along the axis of the steel pipe. The dehumidifying / degreasing machine removes oil and water on the surface of the steel pipe. The automatic shot blasting machine removes the rust film and oxide film on the surface of the steel pipe. The preheating chamber preheats the steel pipe. And the automatic shot blasting machine is arrange | positioned between the dehumidification degreasing machine and the preheating chamber.

  The automatic coating production line further has a spray coating and solidification unit placed after the preheating chamber. The unit includes a spray coating chamber, a coating film solidification chamber, and a cooling chamber that are arranged in order.

  Moreover, the spray coating machine which sprays the coating material containing anti-corrosion coating on the surface of a steel pipe is arrange | positioned in the spray coating room, and the hot air circulation system is arrange | positioned in the coating-film coagulation chamber.

  Instead of the traditional method of manual painting, solidification and cooling in a natural environment, in the present invention, the spray painting and solidification unit mechanically automates all painting, coating solidification and cooling. This unit also improves the efficiency of the coating and greatly reduces the time required for the coating to solidify. The invention takes only 20 minutes, but the conventional method takes 24 hours. Efficiency is improved by 10 times or more. Furthermore, adverse effects on the solidification and cooling of the coating film due to the natural environment can be avoided, and the impact resistance performance can also be improved. At the same time, harm to the operator due to environmental pollution and solvent volatilization is avoided.

  Preferably, the pipe supply mechanism has a plurality of roller pairs that are spaced apart at the same height. Each roller pair is composed of two rollers arranged in parallel and rotatable in the same direction. Further, the distance between two adjacent roller pairs is set so that the steel pipe overlaps at least two roller pairs at the same time when the steel pipe is transferred. Of course, the pipe supply mechanism can be another existing technology.

  Preferably, the spray coating and solidification unit has only two roller pairs respectively arranged in front of the spray coating chamber and after the cooling chamber. Therefore, in the process of applying paint to the steel pipe, solidifying the coating and cooling the coating, the coated steel pipe part does not come into contact with the roller, and the coating film does not adhere to the coating layer and the feeding mechanism. There is no damage.

  Preferably, the two nozzles are arranged to be inclined toward the steel pipe on both sides of the bottom of the steel pipe in the preheating chamber, and the nozzles communicate with the hot air source. The heating rate of this method is high, and the necessary equipment and heating sources are easily found.

  Preferably, the spray coater is a high pressure airless spray coater coupled with an automatic paint heating mechanism. An automatic paint heating mechanism can be located at the inlet of the high pressure airless spray coater and also in the high pressure airless spray coater, ie between the pump of the high pressure airless spray coater and the paint spray flow path. It can also be arranged. Here, the characteristics of the high-pressure airless spray coater are utilized, and the paint can be sprayed in a mist form after being heated. As a result, the content of the solvent in the paint can be greatly reduced, and the coating film can be rapidly solidified.

  Preferably, a plurality of spray coating / coagulation units can be arranged according to the number of coating layers. When a three-layer coating is formed on the surface of a steel pipe, three spray coating and solidification units are arranged side by side. Here, it is specifically designed for processes that usually require these three painting steps: primer (primer) painting, intermediate painting and surface painting.

  Compared with the prior art, in the present invention, in the present invention, the automatic painting method of large steel pipe anticorrosion coating and its production line are used to continuously and automatically process the steel pipe in one production line, for example, to dry and wash. Surface treatment, preheating, painting, and other procedures. The present invention can continuously and automatically process large steel pipes by combining preheating of the steel pipes and high-pressure airless spray coating technology.

  As a result, it is possible to sufficiently reduce the labor intensity of the worker and to improve the production efficiency (more than 10 times can be improved) as compared with the conventional manual painting. The content of the solvent in the paint can be reduced from a typical value of 40% to 60% to less than 10%, and the volatilization of the organic solvent can be reduced 4 to 6 times. Therefore, environmental pollution caused by volatilization of the volatile organic solvent can be reduced. Moreover, energy consumption can be suppressed. The adverse effects of the coating work environment on coating quality can be minimized.

  In addition, the impact resistance performance of the coating layer can be greatly improved, and the GB requirement (50 kg · cm) can be stably satisfied or exceeded as compared with the melted epoxy powder coating method.

  Therefore, in the present invention, the working time is greatly reduced, the manufacturing cost is reduced, and the quality of the anticorrosion coating and the anticorrosion function of the large steel pipe can be guaranteed. In actual tests, technical results beyond expectations will be achieved. It is useful to spread and apply to existing large steel pipes.

4 is a flowchart of a production line according to an exemplary embodiment of the present invention. It is sectional drawing of line AA of FIG. It is sectional drawing of line BB of FIG. It is sectional drawing of line CC of FIG.

  The contents of the school plan will be described in detail with reference to the detailed description of the present invention and the accompanying drawings.

  1 to 4 show an embodiment of the present invention.

  As shown in FIG. 1, in this embodiment, the production line for automatic coating of anticorrosion coating for large steel pipes includes a steel pipe supply mechanism 1, a dehumidifying / degreasing machine 2, an automatic shot blasting machine 3, a preheating chamber 4, and a spray. And a coating / solidifying unit. The spray coating / coagulation unit includes a spray coating chamber 5, a coating film coagulation chamber 6, and a cooling chamber 7. In this embodiment, the steel pipe 8 is coated with a three-layer coating. Accordingly, the three spray coating / coagulation units are arranged in order. That is, the first spray coating / coagulation unit, the second spray coating / coagulation unit, and the third spray coating / coagulation unit are arranged.

  The steel pipe supply mechanism 1 has a plurality of roller pairs that are spaced apart at the same height. Each roller pair is composed of two rollers arranged in parallel and rotatable in the same direction. The extension line of the axis of each roller in each roller pair is inclined with respect to the horizontal, so that the steel pipe 8 is spirally rotated and advanced on the rollers. The distance between two adjacent roller pairs is set so that the steel pipe 8 overlaps at least two roller pairs at the same time when the steel pipe is transferred. The spray coating / solidifying unit has two roller pairs arranged respectively in front of the spray coating chamber 5 and after the cooling chamber 7.

  The dehumidifying / degreasing machine 2 uses a gas boiler diesel burner or other existing equipment. The automatic shot blasting machine 3 uses general equipment. As shown in FIG. 2, in the preheating chamber 4, two nozzles are disposed on both sides of the bottom of the steel pipe 8 so as to be inclined toward the steel pipe 8. The nozzle is in communication with a hot air source. The nozzle heats the steel pipe 8 by spraying hot air obliquely from both sides of the lower part of the steel pipe 8.

  The high-pressure airless spray coating machine 9 is disposed in each spray coating chamber 5. As shown in FIG. 3, the nozzle of the high-pressure airless spray coating machine 9 is disposed at an upper portion of the steel pipe 8 so as to be inclined toward the steel pipe 8. The inlet for painting of the high-pressure airless spray coating machine 9 is connected to the outlet of the automatic paint heating mechanism. This automatic paint heating mechanism is a general automatic paint heating mechanism. A hot air circulation system using a general technique is disposed in each coating film coagulation chamber 6. In the present embodiment, the cooling chamber 7 is cooled using natural wind, but air conditioning can be used as necessary.

  In this embodiment, a three layer coating is painted on the steel pipe 8. That is, an epoxy resin is used as a paint in the base coating. The solvent content in the paint is about 8%. The solidification temperature is 90 ± 10 ° C. In the intermediate coating, epoxy resin is used as a paint. The solvent content in the paint is about 6%. The solidification temperature is 90 ± 10 ° C. Epoxy resin is used as the paint for surface coating. The solvent content in the paint is about 1%. The solidification temperature is 90 ± 10 ° C.

  The automatic coating method of anticorrosion coating on large steel pipes in the production line for automatic coating of large steel pipe anticorrosion coating is performed as follows.

  In step 1, a steel pipe 8 to be coated with a diameter of 1.8 m and a length of 60 m is arranged on the pipe supply mechanism 1 by a lifter. The pipe supply mechanism 1 is started, two rollers rotate in the same direction in each roller pair, and the steel pipe 8 is rotated spirally to advance between the roller pairs. When the steel pipe 8 first passes through the dehumidifying and degreasing machine 2, a flame from a diesel burner is blown onto the surface of the steel pipe 8, thereby removing oil and water on the surface of the steel pipe 8.

  In step 2, after removing oil and water and water, the steel pipe 8 is put into the automatic shot blasting machine 3 to remove the rust film and oxide film on the surface of the steel pipe 8, and the paint is sprayed on the surface of the steel pipe 8. Corresponding to cleanliness and surface roughness required before

  In step 3, as shown in FIG. 2, the steel pipe 8 enters the preheating chamber 4, and two nozzles blow hot air from both sides of the lower part of the steel pipe 8 toward the steel pipe 8. Heat to temperature. Then, the steel pipe 8 is transferred to the spray coating chamber 5.

  In step 4, the automatic heating mechanism heats the paint to a second temperature of 50-70 ° C. and the paint is transferred to the high pressure airless spray coater 9. The paint is mixed with a curing agent, and a mist-like mixture is sprayed from the top of the steel pipe 8 onto the surface of the steel pipe 8. As shown in FIG. 3, the time from when the paint enters the high pressure airless spray coater to when the paint is sprayed can be controlled within 3 minutes.

  In step 5, the steel pipe to which the base coating has been applied is put into the coating film solidification chamber 6. A hot air circulation system is disposed in the coating film coagulation chamber 6 and supplies hot air as shown in FIG. The hot air heats the steel pipe 8 having the base coating from both sides of the steel pipe 8. The steel pipe 8 is heated to a temperature of 90 ± 10 ° C. That is, the coating film of the base coating is quickly solidified. In addition, the hot air circulation system can recover the solvent volatilized from the base coating.

  In step 6, the steel pipe 8 enters the cooling chamber 7. Natural wind is blown from both sides of the steel pipe 8, and the steel pipe 8 is rapidly cooled.

  Two roller pairs are placed in front of the spray coating chamber 5 and after the cooling chamber 7, respectively, so that the coated steel pipe is applied from the application of the base coating to the solidification of the coating and in the process of cooling the coating. This part does not come into contact with the roller, so that the coating film is not damaged by the adhesion between the coating and the supply mechanism.

  In Step 7, the steel pipe 8 having the cooled base coating enters the second spray coating / solidification unit and then the third spray coating / solidification unit in order, and Steps 4, 5 and 6 are repeated. In the second spray coating / coagulation unit, the intermediate coating material is heated to 50 to 70 ° C. by an automatic heater in the spray coating chamber 5, and then the intermediate coating material enters the high-pressure airless spray coating machine 9. The temperature of the coating film coagulation chamber is 90 ± 10 ° C. In the third spray coating / coagulation unit, the temperature of the surface paint entering the high-pressure airless spray coating machine 9 is 50 to 70 ° C. The temperature of the coating film coagulation chamber is 90 ± 10 ° C.

  And the painting process of the large sized steel pipe 8 is complete | finished.

  In the present embodiment, the unrelated parts are the same as in the prior art.

  In the production line described above, when the large steel pipe 8 is coated with a three-layer coating, it takes only 20 minutes for each coating to finish cooling after being solidified from painting. Thus, it takes only an hour to complete a three-layer coating. Automatic operation of the entire procedure greatly reduces work time, improves manufacturing efficiency, and improves coating quality.

DESCRIPTION OF SYMBOLS 1 Steel pipe supply mechanism 2 Dehumidification degreasing machine 3 Automatic shot blasting machine 4 Preheating room 5 Spray coating room 6 Coating film solidification room 7 Cooling room 8 Steel pipe 9 High pressure airless spray coating machine

[Document name] Description [Name of device] Automatic painting production line for anti-corrosion coating on large steel pipes [Technical field]
The present invention relates to an anticorrosion treatment production line for steel pipes, and more particularly to an automatic painting production line for large steel pipes.
[Background]
Large steel pipes generally have a diameter of 0.5 m to 2.4 m and a length of 12 m to 90 m, and are made of steel. In recent years, with the rapid development of China's domestic economy, more and more large steel pipes are used in harbors, docks, ship engineering and urban engineering. In order to effectively suppress the corrosion of the large steel pipe, extend the service life of the large steel pipe, and ensure the safe operation of the infrastructure, it is necessary to treat the surface of the large steel pipe with an anticorrosive agent. The most commonly used anticorrosion treatment is to apply an anticorrosion paint on the surface of the steel pipe. Currently, there are three main methods of applying anticorrosion paint on the surface of large steel pipes in China and other countries. That is, manual painting, melt-baked epoxy (FBE) coating and three-layer polyethylene coating (3LPE).
Here, in the manual painting method, a solvent paint is mainly applied on a large steel pipe. That is, first, shot blasting is performed manually or mechanically on a steel pipe, and then paint is applied on the surface of the steel pipe by manual roll coating or spray coating. In the above-described manual painting, the steel pipe can be treated with an anticorrosive paint, but this method has some disadvantages listed below.
(1) Since the organic solvent content in the paint is relatively high, many organic solvents volatilize during the coating drying process, which not only pollutes the environment but also deteriorates the working environment. This can increase the severity of labor for workers and cause human health problems.
(2) At the same time, when manually painting, the large steel pipe cannot be rotated on site, and the viscosity of the selected paint cannot be sufficiently high, and the organic solvent content in the paint is usually 15 % Or more, which results in a non-uniform phenomenon that hangs down after painting and where the upper side is thin and the lower side is thick, thereby greatly reducing the overall anticorrosion performance of the coating on the steel pipe.
(3) The manual painting of large steel pipes is usually applied in an open indoor or outdoor environment, and as a result of restrictions on the working environment and weather conditions, the time of the painting work depends on the weather. Therefore, the quality, progress and efficiency of large steel pipe painting work cannot be guaranteed. At the same time, after applying the paint, the coating solidifies in a natural environment, spending a long time for solidification, and thus occupying a large work site.
On the other hand, melt-baked epoxy coating is automatically performed on a mechanical production line. As the large steel tube advances in a helical fashion in the drive system, the shot blasting machine removes rust on the surface of the steel tube, and then the steel tube is heated to a temperature by medium frequency induction. Then, the epoxy resin powder is quickly applied onto the surface of the steel pipe by electrostatic coating spray. As soon as the epoxy powder touches the hot steel pipe, it becomes a coating film and adheres to the surface of the steel pipe. Finally, the coating layer is rapidly solidified by rapid water cooling.
Compared to manual painting, melt-baked epoxy painting has clearly increased the degree of automation, and the painting and solidification of the coating is unaffected by the surrounding environment and the weather, resulting in reduced human labor And the efficiency is relatively high. However, it is rarely applied in other countries as a single coating system. It is very large in temperature change, mainly in the coating process. On the other hand, the steel pipe and the coating layer have different expansion coefficients. Therefore, the internal stress of the coating layer on the steel pipe becomes high, and the coating layer is easily damaged under an external force. If the coating layer breaks, it is very difficult to repair in the same way at the construction site.
On the other hand, the three-layer polyethylene coating line is mainly used in an anticorrosion coating line for steel pipes to be buried underground. Most steel pipes processed by this method have a length of about 10 meters, and this method cannot be applied to longer steel pipes. Therefore, three-layer polyethylene coating cannot be applied in rust-preventing coatings on large steel pipes, and this three-layer polyethylene coating is hardly seen in harbors, docks, marine engineering and urban engineering.
Currently, several production lines for large steel pipes are disclosed in Chinese publications CN1673604A, CN16772809A and CN11222772C. In these documents, a primer obtained by adding a primer and tape winding, or a primer using PE as a coating material is disclosed. However, few automatic coating production lines using paints with a high solid content have been reported.
[Patent Document 1] Chinese Patent Publication CN1673604A
[Patent Document 2] Chinese Patent Publication CN16772809A
[Patent Document 3] Chinese Patent Publication CN1122772C
[Outline of the invention]
[Problems to be solved by the invention]
The first object of the present invention is to provide an automatic coating method for an anticorrosion coating on a large steel pipe using a paint having a high solid content, having high coating efficiency, reduced environmental pollution, and good impact resistance performance. It is in.
The second object of the present invention is to provide an automatic coating production line for an anticorrosion coating for large steel pipes using a paint having a high solid content, having high coating efficiency, reduced environmental pollution, and good impact resistance performance. There is.
[Means for Solving the Problems]
In order to achieve the first object, the automatic coating method of the anticorrosion coating on the large steel pipe has the following steps.
In step 1, a steel pipe is arranged in a pipe supply mechanism, and the pipe supply mechanism is started. First, the steel pipe is passed through a dehumidifying and degreasing machine to remove oil and water on the surface of the steel pipe.
In step 2, after removing oil and water and water, put the steel pipe into an automatic shot blasting machine to remove the rust and oxide film on the surface of the steel pipe, and request before spraying the paint on the surface of the steel pipe Corresponding to cleanliness and surface roughness.
In step 3, the steel pipe is put into a preheating chamber, and the temperature of replacement waiting for painting is heated to the first heating temperature. The value of this 1st heating temperature is the temperature range which subtracted 40 to 20 degreeC from the solidification temperature value of the coating material to be used.
In Step 4, after heating, the steel pipe is put into a spray coating chamber. The spray paint machine sprays a second temperature paint onto the surface of the steel pipe. 2nd temperature is the temperature range which subtracted 40 to 20 degreeC from the value of the solidification temperature of the coating material to be used.
In step 5, the steel pipe coated with the paint is put into the coating film solidification chamber. A hot air circulation system is located in the coating solidification chamber, supplying hot air to heat the steel pipe to the solidification temperature of the paint used.
In step 6, the steel pipe is placed in a cooling chamber that rapidly cools. The steel pipe can be cooled by air cooling, water cooling or other cooling methods. In the case of the air cooling, natural wind or cooling air can be used.
In Step 7, when it is necessary to paint the cooled steel pipe with a multilayer coating, the steel pipe is put into the next spray painting / solidifying unit. The next spray coating / coagulation unit is composed of a spray coating chamber, a coating film coagulation chamber, and a cooling chamber in order, and repeats step 4, step 5 and step 6 until all the layers are coated.
In the present invention, both the value of the first temperature in the preheating chamber, which is the preheating temperature of the steel pipe, and the value of the second temperature of the spray paint correspond to the solidification temperature of the selected paint. Therefore, the steel pipe and the coating can be heated synchronously, the coating film can be rapidly solidified, and the solidification time of the coating can be greatly shortened.
In order to further reduce the environmental pollution caused by solvent volatilization in the paint and reduce the number of pinholes in the coating, the solvent content of the paint can be less than 10%.
Preferably, by adopting a system in which hot air is circulated and heated in the coating film coagulation chamber, the cost can be further reduced, the operation can be made safe, and the solidification environment of the coating layer can be improved.
Preferably, the spray coater can be a high pressure airless spray coater, and the time from when the paint enters the high pressure airless spray coater until the paint is sprayed can be limited to 3 minutes. In a high-pressure airless spray coating machine, the temperature at which the paint is sprayed, the time for mixing the curing agent and the paint, and the time between the heating of the paint and the spraying of the paint can be easily controlled.
In order to achieve the second objective, an automatic painting production line of a large steel pipe anticorrosive coating has a supply mechanism, a dehumidifying and degreasing machine, an automatic shot blasting machine, and a preheating chamber for preheating (heating) the steel pipe. . The supply mechanism rotates the steel pipe and moves the steel pipe horizontally along the axis of the steel pipe. The dehumidifying / degreasing machine removes oil and water on the surface of the steel pipe. The automatic shot blasting machine removes the rust film and oxide film on the surface of the steel pipe. The preheating chamber preheats the steel pipe. And the automatic shot blasting machine is arrange | positioned between the dehumidification degreasing machine and the preheating chamber.
The automatic coating production line further has a spray coating and solidification unit placed after the preheating chamber. The unit includes a spray coating chamber, a coating film solidification chamber, and a cooling chamber that are arranged in order.
Moreover, the spray coating machine which sprays the coating material containing anti-corrosion coating on the surface of a steel pipe is arrange | positioned in the spray coating room, and the hot air circulation system is arrange | positioned in the coating-film coagulation chamber.
Instead of the traditional method of manual painting, solidification and cooling in a natural environment, in the present invention, the spray painting and solidification unit mechanically automates all painting, coating solidification and cooling. This unit also improves the efficiency of the coating and greatly reduces the time required for the coating to solidify. The invention takes only 20 minutes, but the conventional method takes 24 hours. Efficiency is improved by 10 times or more. Furthermore, adverse effects on the solidification and cooling of the coating film due to the natural environment can be avoided, and the impact resistance performance can also be improved. At the same time, harm to the operator due to environmental pollution and solvent volatilization is avoided.
Preferably, the pipe supply mechanism has a plurality of roller pairs that are spaced apart at the same height. Each roller pair is composed of two rollers arranged in parallel and rotatable in the same direction. Further, the distance between two adjacent roller pairs is set so that the steel pipe overlaps at least two roller pairs at the same time when the steel pipe is transferred. Of course, the pipe supply mechanism can be another existing technology.
Preferably, the spray coating and solidification unit has only two roller pairs respectively arranged in front of the spray coating chamber and after the cooling chamber. Therefore, in the process of applying paint to the steel pipe, solidifying the coating and cooling the coating, the coated steel pipe part does not come into contact with the roller, and the coating film does not adhere to the coating layer and the feeding mechanism. There is no damage.
Preferably, the two nozzles are arranged to be inclined toward the steel pipe on both sides of the bottom of the steel pipe in the preheating chamber, and the nozzles communicate with the hot air source. The heating rate of this method is high, and the necessary equipment and heating sources are easily found.
Preferably, the spray coater is a high pressure airless spray coater coupled with an automatic paint heating mechanism. An automatic paint heating mechanism can be located at the inlet of the high pressure airless spray coater and also in the high pressure airless spray coater, ie between the pump of the high pressure airless spray coater and the paint spray flow path. It can also be arranged. Here, the characteristics of the high-pressure airless spray coater are utilized, and the paint can be sprayed in a mist form after being heated. As a result, the content of the solvent in the paint can be greatly reduced, and the coating film can be rapidly solidified.
Preferably, a plurality of spray coating / coagulation units can be arranged according to the number of coating layers. When a three-layer coating is formed on the surface of a steel pipe, three spray coating and solidification units are arranged side by side. Here, it is specifically designed for processes that usually require these three painting steps: primer (primer) painting, intermediate painting and surface painting.
Compared with the prior art, in the present invention, in the present invention, the automatic painting method of large steel pipe anticorrosion coating and its production line are used to continuously and automatically process the steel pipe in one production line, for example, to dry and wash. Surface treatment, preheating, painting, and other procedures. The present invention can continuously and automatically process large steel pipes by combining preheating of the steel pipes and high-pressure airless spray coating technology.
As a result, it is possible to sufficiently reduce the labor intensity of the worker and to improve the production efficiency (more than 10 times can be improved) as compared with the conventional manual painting. The content of the solvent in the paint can be reduced from a typical value of 40% to 60% to less than 10%, and the volatilization of the organic solvent can be reduced 4 to 6 times. Therefore, environmental pollution caused by volatilization of the volatile organic solvent can be reduced. Moreover, energy consumption can be suppressed. The adverse effects of the coating work environment on coating quality can be minimized.
In addition, the impact resistance performance of the coating layer can be greatly improved, and the GB requirement (50 kg · cm) can be stably satisfied or exceeded as compared with the melted epoxy powder coating method.
Therefore, in the present invention, the working time is greatly reduced, the manufacturing cost is reduced, and the quality of the anticorrosion coating and the anticorrosion function of the large steel pipe can be guaranteed. In actual tests, technical results beyond expectations will be achieved. It is useful to spread and apply to existing large steel pipes.
[Brief description of the drawings]
FIG. 1 is a flowchart of a production line according to an exemplary embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA of FIG.
FIG. 3 is a cross-sectional view taken along line BB in FIG.
4 is a cross-sectional view taken along line CC in FIG. 1. FIG.
[Mode for carrying out the invention]
The contents of the school plan will be described in detail with reference to the detailed description of the present invention and the accompanying drawings.
1 to 4 show an embodiment of the present invention.
As shown in FIG. 1, in this embodiment, the production line for automatic coating of anticorrosion coating for large steel pipes includes a steel pipe supply mechanism 1, a dehumidifying / degreasing machine 2, an automatic shot blasting machine 3, a preheating chamber 4, and a spray. And a coating / solidifying unit. The spray coating / coagulation unit includes a spray coating chamber 5, a coating film coagulation chamber 6, and a cooling chamber 7. In this embodiment, the steel pipe 8 is coated with a three-layer coating. Accordingly, the three spray coating / coagulation units are arranged in order. That is, the first spray coating / coagulation unit, the second spray coating / coagulation unit, and the third spray coating / coagulation unit are arranged.
The steel pipe supply mechanism 1 has a plurality of roller pairs that are spaced apart at the same height. Each roller pair is composed of two rollers arranged in parallel and rotatable in the same direction. The extension line of the axis of each roller in each roller pair is inclined with respect to the horizontal, so that the steel pipe 8 is spirally rotated and advanced on the rollers. The distance between two adjacent roller pairs is set so that the steel pipe 8 overlaps at least two roller pairs at the same time when the steel pipe is transferred. The spray coating / solidifying unit has two roller pairs arranged respectively in front of the spray coating chamber 5 and after the cooling chamber 7.
The dehumidifying / degreasing machine 2 uses a gas boiler diesel burner or other existing equipment. The automatic shot blasting machine 3 uses general equipment. As shown in FIG. 2, in the preheating chamber 4, two nozzles are disposed on both sides of the bottom of the steel pipe 8 so as to be inclined toward the steel pipe 8. The nozzle is in communication with a hot air source. The nozzle heats the steel pipe 8 by spraying hot air obliquely from both sides of the lower part of the steel pipe 8.
The high-pressure airless spray coating machine 9 is disposed in each spray coating chamber 5. As shown in FIG. 3, the nozzle of the high-pressure airless spray coating machine 9 is disposed at an upper portion of the steel pipe 8 so as to be inclined toward the steel pipe 8. The inlet for painting of the high-pressure airless spray coating machine 9 is connected to the outlet of the automatic paint heating mechanism. This automatic paint heating mechanism is a general automatic paint heating mechanism. A hot air circulation system using a general technique is disposed in each coating film coagulation chamber 6. In the present embodiment, the cooling chamber 7 is cooled using natural wind, but air conditioning can be used as necessary.
In this embodiment, a three layer coating is painted on the steel pipe 8. That is, an epoxy resin is used as a paint in the base coating. The solvent content in the paint is about 8%. The solidification temperature is 90 ± 10 ° C. In the intermediate coating, epoxy resin is used as a paint. The solvent content in the paint is about 6%. The solidification temperature is 90 ± 10 ° C. Epoxy resin is used as the paint for surface coating. The solvent content in the paint is about 1%. The solidification temperature is 90 ± 10 ° C.
The automatic coating method of anticorrosion coating on large steel pipes in the production line for automatic coating of large steel pipe anticorrosion coating is performed as follows.
In step 1, a steel pipe 8 to be coated with a diameter of 1.8 m and a length of 60 m is arranged on the pipe supply mechanism 1 by a lifter. The pipe supply mechanism 1 is started, two rollers rotate in the same direction in each roller pair, and the steel pipe 8 is rotated spirally to advance between the roller pairs. When the steel pipe 8 first passes through the dehumidifying and degreasing machine 2, a flame from a diesel burner is blown onto the surface of the steel pipe 8, thereby removing oil and water on the surface of the steel pipe 8.
In step 2, after removing oil and water and water, the steel pipe 8 is put into the automatic shot blasting machine 3 to remove the rust film and oxide film on the surface of the steel pipe 8, and the paint is sprayed on the surface of the steel pipe 8. Corresponding to cleanliness and surface roughness required before
In step 3, as shown in FIG. 2, the steel pipe 8 enters the preheating chamber 4, and two nozzles blow hot air from both sides of the lower part of the steel pipe 8 toward the steel pipe 8. Heat to temperature. Then, the steel pipe 8 is transferred to the spray coating chamber 5.
In step 4, the automatic heating mechanism heats the paint to a second temperature of 50-70 ° C. and the paint is transferred to the high pressure airless spray coater 9. The paint is mixed with a curing agent, and a mist-like mixture is sprayed from the top of the steel pipe 8 onto the surface of the steel pipe 8. As shown in FIG. 3, the time from when the paint enters the high pressure airless spray coater to when the paint is sprayed can be controlled within 3 minutes.
In step 5, the steel pipe to which the base coating has been applied is put into the coating film solidification chamber 6. A hot air circulation system is disposed in the coating film coagulation chamber 6 and supplies hot air as shown in FIG. The hot air heats the steel pipe 8 having the base coating from both sides of the steel pipe 8. The steel pipe 8 is heated to a temperature of 90 ± 10 ° C. That is, the coating film of the base coating is quickly solidified. In addition, the hot air circulation system can recover the solvent volatilized from the base coating.
In step 6, the steel pipe 8 enters the cooling chamber 7. Natural wind is blown from both sides of the steel pipe 8, and the steel pipe 8 is rapidly cooled.
Two roller pairs are placed in front of the spray coating chamber 5 and after the cooling chamber 7, respectively, so that the coated steel pipe is applied from the application of the base coating to the solidification of the coating and in the process of cooling the coating. This part does not come into contact with the roller, so that the coating film is not damaged by the adhesion between the coating and the supply mechanism.
In Step 7, the steel pipe 8 having the cooled base coating enters the second spray coating / solidification unit and then the third spray coating / solidification unit in order, and Steps 4, 5 and 6 are repeated. In the second spray coating / coagulation unit, the intermediate coating material is heated to 50 to 70 ° C. by an automatic heater in the spray coating chamber 5, and then the intermediate coating material enters the high-pressure airless spray coating machine 9. The temperature of the coating film coagulation chamber is 90 ± 10 ° C. In the third spray coating / coagulation unit, the temperature of the surface paint entering the high-pressure airless spray coating machine 9 is 50 to 70 ° C. The temperature of the coating film coagulation chamber is 90 ± 10 ° C.
And the painting process of the large sized steel pipe 8 is complete | finished.
In the present embodiment, the unrelated parts are the same as in the prior art.
In the production line described above, when the large steel pipe 8 is coated with a three-layer coating, it takes only 20 minutes for each coating to finish cooling after being solidified from painting. Thus, it takes only an hour to complete a three-layer coating. Automatic operation of the entire procedure greatly reduces work time, improves manufacturing efficiency, and improves coating quality.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steel pipe supply mechanism 2 Dehumidification degreasing machine 3 Automatic shot blasting machine 4 Preheating room 5 Spray coating room 6 Coating film solidification room 7 Cooling room 8 Steel pipe 9 High pressure airless spray coating machine

Claims (10)

An automatic painting method for a corrosion protection coating on a large steel pipe, the characteristics of which includes the following steps:
In Step 1, a steel pipe is arranged in a pipe supply mechanism, the pipe supply mechanism is started, and first, the steel pipe is passed through a dehumidifying and degreasing machine to remove oil and water on the surface of the steel pipe.
In step 2, after removing oil and water and water, put the steel pipe into an automatic shot blasting machine to remove the rust and oxide film on the surface of the steel pipe, and request before spraying the paint on the surface of the steel pipe Corresponding to the cleanliness and surface roughness
In Step 3, the steel pipe is put into a preheating chamber, and the temperature of the waiting for coating is heated to the first heating temperature. The value of the first heating temperature is subtracted from 40 ° C. to 20 ° C. from the solidification temperature value of the paint used. Temperature range,
In Step 4, after heating, the steel pipe is put into a spray coating chamber, and the spray paint machine sprays the second temperature paint onto the surface of the steel pipe, and the second temperature is calculated from the solidification temperature value of the paint used. The temperature range minus 20 ° C,
In Step 5, the steel pipe coated with the paint is put into the coating film coagulation chamber, and a hot air circulation system is arranged in the coating film coagulation chamber, supplying hot air to heat the steel pipe to the solidification temperature of the used paint. And
In Step 6, the steel pipe is put into a cooling chamber and rapidly cooled,
In Step 7, when it is necessary to paint the steel pipe after cooling with multi-layer coating, the steel pipe is put into the next spray painting / solidification unit, and it is composed of the spray painting room, the coating film solidification room and the cooling room in order. Step 4, Step 5 and Step 6 are repeated in the spray coating / coagulation unit until all layers have been coated.   It is the automatic painting method of the anticorrosion coating of the large sized steel pipe of Claim 1, Comprising: The characteristic can make content of the solvent of the said paint less than 10%.   The automatic coating method for an anti-corrosion coating on a large steel pipe according to claim 1, which is characterized by employing a system in which hot air is circulated and heated in the coating film coagulation chamber. It is the automatic painting method of the anticorrosion coating of the large sized steel pipe of Claim 1, Comprising: The characteristic is
The spray coater is a high pressure airless spray coater that limits the time from when the paint enters the high pressure airless spray coater to when the paint is sprayed within 3 minutes. It is an automatic painting production line for large steel pipe anticorrosion coating,
A feeding mechanism for rotating the steel pipe and moving the steel pipe horizontally along the axis of the steel pipe;
A dehumidifying and degreasing machine for removing oil and water on the surface of the steel pipe;
An automatic shot blasting machine to remove the rust film and oxide film on the surface of the steel pipe;
A preheating chamber for preheating the steel pipe;
In automatic painting production line with
The automatic shot blasting machine is located between the dehumidifying and degreasing machine and the preheating chamber,
The automatic painting production line
A spray coating / coagulation unit is arranged after the preheating chamber, and the unit includes a spray coating chamber, a coating film coagulation chamber, and a cooling chamber arranged in order,
In the spray painting room, there is a spray coating machine that sprays paint and applies an anticorrosion coating to the surface of the steel pipe.
A hot air circulation system is arranged in the coating film coagulation chamber.
Automatic painting production line. The production line according to claim 5, wherein the pipe supply mechanism has a plurality of pairs of rollers arranged at the same height and spaced apart from each other.
Each roller pair is composed of two rollers arranged in parallel and rotatable in the same direction,
The distance between two adjacent roller pairs is set so that the steel pipe overlaps at least two roller pairs simultaneously when transporting the steel pipe,
Automatic painting production line. The production line according to claim 6, wherein the spray coating / solidification unit has only two roller pairs respectively arranged in front of the spray coating chamber and after the cooling chamber.
Automatic painting production line. The production line according to claim 5, wherein the two nozzles are disposed to be inclined toward the steel pipe on both sides of the bottom of the steel pipe in the preheating chamber, and the nozzle communicates with a hot air source.
Automatic painting production line. The production line according to claim 5, wherein the spray coating machine is a high-pressure airless spray coating machine connected to an automatic paint heating mechanism.
Automatic painting production line. The production line according to claim 5, wherein three spray coating / coagulation units are arranged in order,
Automatic painting production line.

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