JP2014087759A - Pipe inner surface coating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly coat an uneven socket inner surface of a cast iron pipe, in a pipe inner surface coating device for spraying paint on a cast iron pipe inner surface.SOLUTION: A notch groove 16b extending in a radial shape from the periphery of its top part 16a, is provided in a plurality on an outer surface of a head part 16 formed in a dome shape as a spray nozzle 10 for injecting the paint mixed with air, and even an inner surface of an uneven socket 13 of the cast iron pipe 11 can be uniformly coated without omission of coating and coating nonuniformity within a range of a proper coating film thickness by obtaining a spray pattern expanding over a wide range in the axial direction and the circumferential direction of the cast iron pipe 11 by expanding the paint injected from respective injection ports 16c of this spray nozzle 10 along the notch grooves 16b, by providing the injection ports 16c of the paint on a bottom surface of these respective notch grooves 16b.

Description

  The present invention relates to a pipe inner surface coating apparatus that performs coating on the inner surface of a cast iron pipe.

  For cast iron pipes widely used for water pipes, etc., the straight part with a constant inner and outer diameter and one end of the straight part are continuous, and the receiving port whose inner and outer diameter is larger than the direct part and the other end of the straight part. However, there are many things which consist of the insertion port inserted in the receiving port of another cast iron pipe. When anticorrosion coating is performed on the inner and outer surfaces of such a cast iron pipe, a zinc-based primer is generally applied as an undercoat. As the zinc-based primer, water-based zinc rich paint is often used in consideration of the environment.

  On the other hand, as a coating apparatus (pipe inner surface coating apparatus) for coating the inner surface of a cast iron pipe, a type in which the paint is mixed with air, sprayed from the spray nozzle and sprayed onto the inner surface of the cast iron pipe is used. There are many cases. As the spray nozzle, generally, as shown in FIGS. 4A to 4C, a cut groove 52 extending in the radial direction is provided on the outer surface of the top of the head 51 formed in a dome shape. What provided the injection port 53 in the bottom face of the insertion groove | channel 52 is used.

  However, when undercoating water-based zinc rich paint on the inner surface of a cast iron pipe receptacle using the above-described pipe inner surface coating apparatus, the inner surface shape of the receptacle is a complicated one having irregularities, Uneven coating is likely to occur and it is difficult to uniformly coat the surface perpendicular to the inner peripheral surface of the pipe.

  In particular, when the cast iron pipe to be coated has a small diameter (nominal diameter of about 75 mm to 100 mm), the distance between the spray nozzle and the inner surface of the pipe is shortened, so that the paint sprayed from the spray port 53 at the tip of the spray nozzle ( Water-based zinc rich paint) does not spread sufficiently, and there are many cases where coating leakage occurs on the surface orthogonal to the inner peripheral surface of the pipe. On the other hand, when the discharge speed of the paint is increased or the discharge amount is increased in order to eliminate the omission of coating, the thickness of the coating film is increased, and the coating film is easily peeled off in the next step.

  On the other hand, in Patent Document 1, a coating apparatus having a brush in which hairs are spirally arranged on the outer peripheral surface of the central shaft is used, and the brush to which the paint is attached is inserted into the receiving port of the cast iron pipe, It has been proposed to perform coating that does not cause coating leakage by rotating around the axis, corresponding to the unevenness of the inner surface of the receiving port.

Japanese Patent Laid-Open No. 11-253857

  In the coating apparatus described in Patent Document 1, it is said that the inner surface of the receiving end of the cast iron pipe can be coated without causing omission, but there is a risk that the coating quality may be deteriorated due to brushing or wear due to repeated use. There is. Moreover, in order to prevent the deterioration of the coating quality, it is necessary to manage a brush finely and there also exists a problem that a maintenance takes time.

  Accordingly, an object of the present invention is to enable uniform coating of the inner surface of the cast iron pipe with irregularities in a pipe inner surface coating apparatus that sprays paint onto the inner surface of the cast iron pipe.

  In order to solve the above-mentioned problems, the present invention is a pipe inner surface coating apparatus in which a paint is mixed with air, sprayed from a spray nozzle, and sprayed onto the inner surface of a cast iron pipe. The spray nozzle is formed in a dome shape. A plurality of cut grooves extending radially from the periphery of the top of the head were provided on the outer surface of the head, and the injection port was provided on the bottom of each of the cut grooves. According to this configuration, even if the distance between the spray nozzle and the inner surface of the pipe is short, a spray pattern in which the paint sprayed from the injection port is sufficiently spread is obtained, and the uneven inner surface of the cast iron pipe is evenly coated. be able to.

  Said structure WHEREIN: It is desirable that the angle which the notch grooves adjacent in the circumferential direction of the head of the said spray nozzle make is 45 to 60 degree | times. Moreover, as for the width | variety of each cutting groove of the said spray nozzle, it is desirable to set it as 1.0 mm-1.5 mm. This is because if the width of the cut groove is less than 1.0 mm, the coating path is likely to be clogged, and if it exceeds 1.5 mm, the head of the spray nozzle is likely to be damaged.

  The present invention can be applied particularly effectively when the paint is a water-based zinc rich paint.

  As described above, the pipe inner surface coating apparatus of the present invention has a plurality of cut grooves extending radially from the periphery of the top portion on the outer surface of the head formed in a dome shape, and the bottom surface of each of these cut grooves. A cast nozzle with a spray nozzle is adopted, so that even if the distance between the spray nozzle and the inner surface of the pipe is short, a spray pattern that allows the paint sprayed from the spray nozzle to spread sufficiently is obtained. The inner surface of the receptacle with irregularities on the pipe can be evenly applied without omission or unevenness within the range of the appropriate coating thickness, and the coating quality of the cast iron pipe can be improved.

Schematic of painting work by the pipe inner surface painting device of the embodiment a is a perspective view of the spray nozzle of FIG. 1, b to d are side view, front view and side sectional view of a, respectively. a is a side view of a modified example of the spray nozzle, b and c are a front view and a side sectional view of a, respectively. a is a side view of a conventional spray nozzle, b and c are a front view and a side sectional view of a, respectively.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the pipe inner surface coating apparatus 1 includes a paint tank 3 that stores paint 2, a tank air source 4 that sends air to the paint tank 3, and an electric motor that stirs the paint 2 in the paint tank 3. A paint stirrer 5, a paint gun 6 to which paint 2 is supplied from the paint tank 3, and a gun air source 7 for sending air to the paint gun 6, and an inner surface of the cast iron pipe 11 with water-based zinc rich paint as the paint 2 Are undercoated.

  The coating gun 6 includes a gun body 8 to which the paint 2 and air are supplied, a tube body 9 attached to the distal end side of the gun body 8 and having a distal end formed in an L shape, and a distal end of the tube body 9. It is comprised with the spray nozzle 10 with which it mounts | wears.

  Then, air is sent from the tank air source 4 to the paint tank 3 to pressurize the air in the paint tank 3, and the paint 2 is supplied from the paint tank 3 to the paint gun 6. By supplying air to the coating gun 6, the paint 2 mixed with air in the gun body 8 of the coating gun 6 passes through the tube body 9 and is sprayed from the spray nozzle 10.

  On the other hand, the cast iron pipe 11 to be coated is connected to the straight portion 12 having a constant inner and outer diameter, one end of the straight portion 12, the receiving port 13 having an inner and outer diameter larger than the straight portion 12, and the other end of the straight portion 12. It consists of an insertion port 14 that is continuous and is inserted into a receiving port (not shown) of another cast iron pipe. The inner surface of the receiving port 13 is provided with annular protrusions 13a and 13b and an annular groove 13c, thereby forming irregularities.

  When undercoating the inner surface of the receiving port 13 of the cast iron pipe 11, two portions in the axial direction of the cast iron tube 11 are supported by the rotating roller 15, and the tip side portion or the whole of the coating gun 6 is placed inside the receiving port 13. insert. In this state, the rotary roller 15 is driven to rotate the cast iron pipe 11 around the axis, and the paint gun 6 is moved in the axial direction of the cast iron pipe 11 while moving from the spray nozzle 10 of the paint gun 6 to the inner surface of the receiving port 13. Directly spray the paint 2 mixed with air.

  Here, as shown in FIGS. 2A to 2D, the spray nozzle 10 includes a head 16 formed in a dome shape, a hollow body portion 17 having a hexagonal nut shape, and an outer peripheral surface. A paint passage 19 is formed in the inside of the leg portion 18 which has a male thread and opens to the end face of the leg portion 18. In addition, on the outer surface of the head 16, the cut grooves 16 b extending radially from the periphery of the top portion 16 a to the body portion 17 have an angle of 45 degrees between adjacent ones in the circumferential direction of the head 16. Eight nozzles are provided, and an injection port 16c communicating with the paint passage 19 is provided on the bottom surface of each of the cut grooves 16b. The width of the cut groove 16b is set to 1.0 mm to 1.5 mm so that the path of the paint 2 is not clogged and the head 16 is not damaged.

  When the paint gun 6 is operated by screwing the leg portion 18 of the spray nozzle 10 to the tip of the tube body 9, the paint 2 mixed with air in the gun body 8 is sprayed from the tube body 9 to the spray nozzle. 10 flows into the paint passage 19, is sprayed from the spray ports 16 c of the head 16 of the spray nozzle 10, and is sprayed onto the inner surface of the receiving port 13 of the cast iron pipe 11. At this time, since the paint 2 sprayed from each spray port 16c spreads along the eight cut grooves 16b provided radially, a spray pattern that spreads over a wide range in the axial direction and the circumferential direction of the cast iron pipe 11 is obtained. . On the other hand, since the top 16a of the head 16 is closed, the coating thickness does not become too thick immediately below the spray nozzle 10.

  This pipe inner surface coating apparatus 1 has the above-described configuration, and even when the cast iron pipe 11 to be coated has a small diameter and the distance between the spray nozzle 10 and the inner surface of the cast iron pipe 11 is shortened, the pipe inner face coating apparatus 1 is connected to the spray nozzle 10 from the injection port 16c. Since a spray pattern in which the sprayed paint 2 is sufficiently spread is obtained, the uneven inner surface of the receiving port 13 can be uniformly applied without omission or uneven coating.

  3A to 3C show modified examples of the spray nozzle 10. In this modified example, six cut grooves 16b of the dome-shaped head portion 16 are provided so that an angle between adjacent ones in the circumferential direction of the head portion 16 is 60 degrees, and the bottom surface of each cut groove 16b is provided. An injection port 16c is provided. Even in this modified example, a spray pattern in which the paint 2 spreads sufficiently can be obtained, and the inner surface of the receiving port 13 can be uniformly coated.

  On the other hand, in the case of using the one in which the cut groove 16b of the spray nozzle 10 of FIG. 2 is eliminated and the eight injection ports 16c are directly provided on the outer surface of the head 16 (comparative example), the inner peripheral surface of the receiving port 13 is used. In addition, coating omission and coating unevenness occurred on any of the surfaces orthogonal thereto, and the required coating quality could not be obtained. Thereby, the effect of providing the radial cut grooves 16b in the head 16 of the spray nozzle 10 as in the examples of FIGS. 2 and 3 is further clarified.

  The present invention can be particularly effectively applied to the water-based zinc rich paint coating on the inner surface of the small-diameter pipe as described above. However, the present invention is not limited to this, and when the diameter of the cast iron pipe to be coated is large, the water-based zinc rich paint The present invention can also be applied when a paint other than the above is used. Of course, the inner surface of the cast iron pipe other than the receptacle can also be painted with the pipe inner surface coating apparatus of the present invention.

1 Pipe inner surface coating equipment 2 Paint (water-based zinc rich paint)
6 Coating Gun 10 Spray Nozzle 11 Cast Iron Pipe 13 Receptacle 16 Head 16a Top 16b Cut Groove 16c Injection Port

Claims (4)

  In a pipe inner surface coating apparatus in which paint is mixed with air, sprayed from the spray nozzle outlet, and sprayed onto the inner surface of the cast iron pipe, the spray nozzle is formed on the outer surface of the head formed in a dome shape from the periphery of the top. A pipe inner surface coating apparatus, wherein a plurality of radially extending cut grooves are provided, and the injection port is provided on the bottom surface of each of the cut grooves.   2. The pipe inner surface coating apparatus according to claim 1, wherein an angle formed between adjacent cut grooves in a circumferential direction of the head of the spray nozzle is set to 45 degrees to 60 degrees.   The pipe inner surface coating apparatus according to claim 1 or 2, wherein a width of each cut groove of the spray nozzle is set to 1.0 mm to 1.5 mm.   The pipe inner surface coating apparatus according to any one of claims 1 to 3, wherein the paint is a water-based zinc rich paint.

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