JP2015224375A - Liquid application device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid application device that has simple constitution and can apply liquid such as solution of chemical conversion treatment onto an outer circumferential surface of a steel tube stably and uniformly in a high yield.SOLUTION: The liquid application device according to the present invention is configured to apply liquid onto an outer circumferential surface of a steel tube, and includes: a transport roller which transports the steel tube along a longitudinal direction; an application member comprised of an elastic body having a through hole through which the steel tube passes and having, in the surface of the elastic body, a groove extending from a top part of the through hole to outside the through hole; a liquid feed tube which is inserted into the groove of the application member; and a pump which supplies the liquid to the liquid feed tube. The application member is preferably a sponge made of polyurethane. The liquid may be solution of chemical conversion treatment or anti-rust agent. The solution of chemical conversion treatment may be an ammonium zirconium carbonate solution.

Description

  The present invention relates to a liquid application apparatus for applying a liquid to an outer peripheral surface of a steel pipe.

  In order to improve the properties of the outer peripheral surface of the steel pipe, it is common practice to apply a liquid to the outer peripheral surface of the steel pipe. As an example thereof, there is a chemical conversion treatment as a base treatment in a resin-coated steel pipe.

  A resin-coated steel pipe whose outer peripheral surface is coated with a resin has high corrosion resistance. Therefore, resin-coated steel pipes are widely used for crude oil line pipes, city gas supply pipes, plant pipes, water pipes, and the like. In these applications, since it is necessary to maintain high corrosion resistance, high adhesion is required for the resin coated on the outer peripheral surface of the steel pipe. Therefore, a chemical conversion treatment has been conventionally performed on the outer peripheral surface of the steel pipe as a base treatment before coating the resin.

  For example, in Japanese Patent Application Laid-Open No. 9-201902 (Patent Document 1) and Japanese Utility Model Publication No. 3-18502 (Patent Document 2), a chromate treatment is performed as a chemical conversion treatment as a base treatment in order to improve the adhesion of the resin. Is described.

  In Patent Document 1, a chromate treatment liquid is excessively sprayed as a shower from a nozzle above a steel pipe that passes through a treatment chamber of a chromate treatment agent coating apparatus, and the surface of the steel pipe is covered by a squeezing member disposed at the outlet of the treatment chamber. A method is described in which the surface properties of the chromate treatment layer are made uniform by ironing.

  Patent Document 2 describes a method in which a steel pipe is conveyed in the longitudinal direction while being rotated in the circumferential direction (skew conveyance), and at that time, a chromate treatment liquid is spirally applied to the surface of the steel pipe using a roll coater. ing.

  Japanese Unexamined Patent Application Publication No. 2009-256699 (Patent Document 3) describes a method using a roll coater as a method of applying a chemical conversion treatment liquid to a steel sheet. Since hexavalent chromium contained in the chromate treatment liquid is subject to environmental regulations, Patent Document 3 describes a method of using a chemical conversion treatment liquid that does not have restrictions on environmental regulations as an alternative to the chromate treatment liquid. .

JP-A-9-201902 No. 3-18502 JP 2009-256699 A

  In the method described in Patent Document 1, a large amount of chromate treatment liquid is used because the chromate treatment liquid is sprayed in a larger amount than the amount of liquid applied to the steel pipe surface. However, the chromate treatment liquid has excellent stability in the air, and the chromate treatment liquid dropped from the steel pipe can be recovered and circulated for use. For this reason, in the method described in Patent Document 1, the chromate treatment solution can be used with a high yield.

  However, many chemical conversion treatment liquids (hereinafter referred to as “alternative chemical conversion treatment liquids”) that are alternative to chromate treatment liquids are less stable in air than chromate treatment liquids. As a method of applying the alternative chemical conversion treatment liquid, when circulation use is applied in the same manner as the chromate treatment liquid, the deterioration of the liquid due to contact with air significantly proceeds. Therefore, the alternative chemical conversion treatment liquid cannot be used in a circulating manner. On the other hand, in order to minimize the use amount of the alternative chemical conversion treatment liquid, when the required amount of the alternative chemical conversion treatment liquid is dropped, the alternative chemical conversion treatment liquid dropped from above the steel pipe when the conveyed steel pipe vibrates in the left-right direction. However, it does not sag on both sides of the steel pipe, and there is a problem that an unpainted alternative chemical treatment liquid is left on one of the outer peripheral surfaces of the steel pipe.

  As in the methods described in Patent Documents 2 and 3, in the method of applying the chemical conversion treatment liquid with a roll coater, the minimum necessary amount of chemical conversion treatment liquid can be applied. For this reason, a chemical conversion liquid can be used with a high yield. However, when a chemical conversion liquid is applied to a steel pipe with a roll coater, there is a problem that the apparatus becomes complicated.

  The present invention has been made in view of these problems, has a simple configuration, and can apply a liquid such as a chemical conversion treatment liquid to the outer peripheral surface of a steel pipe stably and uniformly at a high yield. An object is to provide a coating apparatus.

  The liquid coating apparatus of the present invention is a liquid coating apparatus that applies a liquid to an outer peripheral surface of a steel pipe, and includes a transport roller that transports the steel pipe along a longitudinal direction, a through-hole for passing the steel pipe, and the penetration A coating member made of an elastic body having a groove on the surface from the uppermost part of the hole toward the outside of the through hole, a liquid supply tube inserted into the groove of the coating member, and a liquid to the liquid supply tube A pump to be supplied.

  In the liquid application apparatus, the application member is preferably a sponge made of polyurethane. The liquid may be a chemical conversion treatment liquid or a rust inhibitor. The chemical conversion treatment liquid can be, for example, an aqueous solution mainly composed of ammonium zirconium carbonate.

  According to the liquid application apparatus of the present invention, the liquid can be stably and uniformly applied to the outer peripheral surface of the steel pipe with a high yield by an apparatus having a simple configuration.

FIG. 1 is a partial configuration diagram of a liquid coating apparatus according to the present invention, in which FIG. 1 (a) is a front view and FIG. 1 (b) is a side view.

  FIG. 1 is a partial configuration diagram of a liquid coating apparatus according to the present invention, in which FIG. 1 (a) is a front view and FIG. 1 (b) is a side view. The steel pipe is also shown in FIG. The liquid application apparatus of the present invention includes an application member 1 and a liquid supply tube 4.

  The application member 1 is made of an elastic body and has a through hole 2 through which the steel pipe 6 passes. The applicator member 1 is arranged vertically, and has a groove 3 on one surface from the uppermost part of the through hole 2 toward the outer side of the through hole 2. The application member 1 is disposed so that the surface on which the groove 3 is provided is on the upstream side in the steel pipe conveyance direction.

  The inner diameter of the through hole 2 is equal to or smaller than the outer diameter of the steel pipe 6. Thereby, the application member 1 elastically contacts the entire outer periphery of the steel pipe 6 along the entire circumference of the through hole 2. Since the lower limit of the inner diameter of the through hole 2 is set in consideration of the elongation of the application member 1, it varies depending on the material of the application member 1. For example, when the application member 1 is a sponge made of foamed polyurethane and the outer diameter of the steel pipe 6 is 60 mm, the lower limit of the inner diameter of the through hole 2 is preferably 50 mm, which is smaller by about 10 mm.

  One end of a liquid supply tube 4 for supplying a liquid is inserted into and fixed to the upper part of the groove 3 provided on the surface of the application member 1. The other end of the liquid supply tube 4 is connected to a container 5 that stores liquid.

  The liquid application apparatus includes a pump (not shown). The pump is disposed between the container 5 and the liquid supply tube 4. The pump can sequentially supply a predetermined amount of liquid to the liquid supply tube 4. Depending on the amount of liquid required, a plurality of liquid supply tubes 4 may be inserted into the grooves 3, and a pump may be disposed in each liquid supply tube 4.

  The liquid application apparatus includes a conveyance roller (not shown). The conveyance rollers are arranged on the upstream side and the downstream side in the steel pipe conveyance direction of the application member 1. The steel pipe 6 is transported using this transport roller and transported along the longitudinal direction of the steel pipe 6.

  When the liquid is applied to the outer peripheral surface of the steel pipe, as shown in FIG. 1B, the steel pipe 6 is transported horizontally along the longitudinal direction, and the steel pipe 6 is passed through the through hole 2 of the application member 1. At that time, the steel pipe 6 is passed through the through hole 2 while injecting liquid from the liquid supply tube 4 into the groove 3 of the application member 1. The injected liquid reaches the uppermost part of the through-hole 2 through the groove 3, and all of the through-hole 2 is caused by a capillary phenomenon due to a minute gap formed between the outer peripheral surface of the steel pipe 6 and the through-hole 2. Supplied around the lap. Since the entire outer periphery of the steel pipe 6 is in contact with the entire periphery of the through hole 2, the liquid can be uniformly applied to the entire outer peripheral surface of the steel pipe 6. At this time, the liquid can be applied to the entire outer peripheral surface of the steel pipe 6 with a high yield by minimizing the injection amount of the liquid. The injection amount of the liquid varies depending on the diameter of the steel pipe and the conveying speed. For example, when conveying a steel pipe having an outer diameter of 60 mm at a speed of about 10 m / min, 100 to 200 mL / min is preferable. When transporting at a speed of about 2 m / min, 200 to 300 mL / min is preferable.

  The liquid container 5 and the pump are preferably highly airtight. This is because even if the liquid easily changes its characteristics when it comes into contact with air, the change in the characteristics of the liquid can be minimized. Therefore, the liquid yield can be further improved. An example of the highly airtight pump is a metering tubing pump. Since the metering tubing pump can control the liquid injection amount with high accuracy, the liquid can be injected without excess or deficiency.

  By arrange | positioning the steel pipe 6 and the through-hole 2 so that it may become concentric, the stress of the application member 1 which contacts the outer periphery of the steel pipe 6 can be made constant over the outer periphery of the steel pipe 6, and a liquid is apply | coated more uniformly. be able to.

  The liquid supply tube 4 preferably has the same or higher flexibility than the elastic body constituting the application member 1, and for example, a silicone tube can be used. By making the liquid supply tube 4 flexible, the coating member 1 and the liquid supply tube 4 follow the steel pipe 6 even when the steel pipe 6 passing through the through hole 2 vibrates. The liquid can be applied to the outer peripheral surface of the film.

  The groove 3 provided in the coating member 1 may be a groove formed by cutting the surface of the coating member 1 or may have a certain width. The width W of the groove 3 is preferably 1 mm or less. The depth D of the groove 3 is preferably 10 to 30% of the thickness T of the application member 1. The thickness T of the application member 1 is preferably 30 to 80 mm.

  The length L of the groove 3 is not particularly limited. However, if the groove 3 is too long, the flow of the liquid supplied from the liquid supply tube 4 inserted in the upper part of the groove 3 may become unstable. On the other hand, if the groove 3 is too short, when the steel pipe 6 to be conveyed vibrates in the vertical direction, the liquid supply tube 4 and the steel pipe 6 may come into contact with each other, and the liquid application state may be adversely affected. Therefore, the length L of the groove 3 is preferably 10 to 50 mm.

  In addition to the uppermost groove 3 of the through hole 2, the application member 1 may be further provided with an additional groove. Even when it is necessary to apply a large amount of liquid as in the case where the outer diameter of the steel pipe 6 is large by providing an additional groove and inserting a liquid supply tube into each groove and supplying the liquid, the steel pipe 6 The liquid can be uniformly applied to the outer peripheral surface of the film. The additional groove is preferably provided on the same surface as the groove 3 so as to be symmetrical with respect to the groove 3 in the steel pipe conveying direction.

  A plurality of application members 1 may be arranged along the steel pipe conveyance direction. In this case, the liquid supply tube 4 is inserted into the groove 3 of each application member 1. By arranging a plurality of application members 1, the liquid can be applied more uniformly.

  The elastic body constituting the application member 1 is preferably a sponge made of polyurethane. By using the application member 1 as a sponge, the liquid supplied from the liquid supply tube 4 to the groove 3 not only travels along the surface of the sponge, but a part of the liquid is once absorbed by the sponge and passes through the sponge 2. Is applied to the outer peripheral surface of the steel pipe 6. Since the sponge can hold the liquid inside unlike the rubber or the like, the liquid dripping below the steel pipe 6 can be reduced even when extra liquid is supplied, and the yield of the liquid can be improved.

  As the liquid applied to the outer peripheral surface of the steel pipe 6, a chemical conversion treatment liquid used for the base treatment of the outer peripheral surface of the steel pipe 6 can be applied before the steel pipe 6 is coated with resin. Examples of the chemical conversion treatment solution include an aqueous solution mainly composed of ammonium zirconium carbonate. Since aqueous solutions containing ammonium zirconium carbonate as a main component are not subject to environmental regulations, it is possible to obtain a resin-coated steel pipe with a low environmental load by using an aqueous solution containing ammonium zirconium carbonate as a main component as a chemical conversion treatment liquid. it can. The aqueous solution containing ammonium zirconium carbonate as a main component preferably has a zirconium zirconium carbonate content of 0.05 to 10.00% by mass in terms of metal zirconium.

  An aqueous solution mainly composed of ammonium zirconium carbonate has a lower stability in air than a chromate treatment solution. However, according to the liquid coating apparatus of the present invention, since contact with air can be minimized, it is possible to stably coat the outer peripheral surface of the steel pipe with a high yield over a long period of time.

  The reason why the aqueous solution containing ammonium zirconium carbonate as a main component is low in air is that the pH of the aqueous solution containing zirconium ammonium carbonate as a main component is lowered by carbon dioxide in the air, so that dissolved ions are precipitated. It is thought to be due to.

  Moreover, the liquid apply | coated to the outer peripheral surface of the steel pipe 6 can be used as a rust preventive agent. According to the liquid coating apparatus of the present invention, it is possible to obtain a steel pipe subjected to rust prevention treatment with a high yield.

  In order to confirm the effect of the liquid coating apparatus of the present invention, the following tests were performed and the results were evaluated.

1. Test conditions An apparatus having the structure shown in FIG. 1 was used as the liquid coating apparatus. One coating member was used. The steel pipes used were two types of test numbers 1 and 2 shown in Table 1. The outer peripheral surface of each steel pipe was blasted beforehand. Table 1 shows the dimensions of the steel pipe of each test number and the roughness of the outer peripheral surface after blasting (ten-point average roughness).

The elastic body used for the application member was a sponge made of a soft polyurethane foam (polyether polyol-based urethane resin) in both test numbers 1 and 2. The characteristics of this flexible polyurethane foam are as follows.
Apparent density: 20 ± 1.5 kg / m ³
40% hardness: 100 ± 20 N / 314 cm ² ,
25% hardness: 90 ± 20 N / 314 cm ² ,
Tensile strength: 70 kPa or more,
Elongation rate: 150% or more,
Tear strength: 4 N / cm or more,
Rebound resilience: 40% or more,
Compression residual strain (new): 10% or less,
Compression residual strain (old): 5% or less,
Repeated compression residual strain: 5% or less.

  The thicknesses of the application members of Test Nos. 1 and 2, the inner diameter of the through holes, the depth of the grooves, and the length of the grooves were as shown in Table 1.

  Using these steel pipes and application members, a liquid application test was conducted at the steel pipe conveyance speed and liquid injection speed shown in Table 1. The liquid to be applied was an aqueous solution mainly composed of ammonium zirconium carbonate (content of ammonium zirconium carbonate: 3.0% by mass).

2. Test result The application state of the liquid was visually confirmed and judged to be good when there was no discernible unevenness. As a result of the application test, in both test numbers 1 and 2, there was no visible unevenness, and the liquid application state on the outer peripheral surface of the steel pipe was good.

  According to the liquid application apparatus of the present invention, the liquid can be stably and uniformly applied to the outer peripheral surface of the steel pipe with a high yield by an apparatus having a simple configuration.

1: coating member, 2: through hole, 3: groove, 4: liquid supply tube, 5: container, 6: steel pipe

Claims (5)

A liquid application device for applying a liquid to the outer peripheral surface of a steel pipe,
A transport roller for transporting the steel pipe along the longitudinal direction;
A through-hole for passing the steel pipe, and an application member made of an elastic body having a groove on the surface from the uppermost part of the through-hole toward the outer side of the through-hole;
A liquid supply tube inserted into the groove of the application member;
A liquid application apparatus comprising: a pump that supplies liquid to the liquid supply tube. The liquid coating apparatus according to claim 1,
The liquid application apparatus, wherein the application member is a sponge made of polyurethane. The liquid application apparatus according to claim 1 or 2,
A liquid coating apparatus, wherein the liquid is a chemical conversion treatment liquid. The liquid coating apparatus according to claim 3,
A liquid coating apparatus, wherein the chemical conversion treatment liquid is an aqueous solution mainly composed of ammonium zirconium carbonate. The liquid application apparatus according to claim 1 or 2,
A liquid coating apparatus, wherein the liquid is a rust inhibitor.

Images