JP4833132B2 - How to paint the outer peripheral surface of the tube - Google Patents

Description

  The present invention relates to a method for coating an outer peripheral surface of a tubular body that performs coating on the outer peripheral surface of a tubular body using a spray gun, and a coating device for the outer peripheral surface of a tubular body.

As a technique for coating the outer peripheral surface of a tubular body, for example, there is a coating method in which paint is sprayed on the outer peripheral surface of the tubular body with a spray gun while rotating the tubular body around the tube axis.
This coating method will be described with reference to FIGS. 1 and 2, which are explanatory views of an embodiment of the present invention. The tube p is placed on and supported by the roller 1, and the roller 1 is rotated by a driving force. The tube p is rotated. As the tube p rotates, the paint is supplied to the spray gun 10 by an airless pump system, and the spray gun 10 and the tube p are moved while discharging the paint toward the outer peripheral surface of the tube p by the spray gun 10. Relative movement is performed along the tube axis direction (see, for example, Patent Document 1).
JP 2002-282766 A (page 7, FIGS. 6 and 7)

Further, as the nozzle 11 attached to the tip of the spray gun 10, a paint spray pattern (planar shape of the coating portion formed when sprayed at a fixed position for a short time) is an ellipse in plan view. There is also an ellipse whose major axis direction is the same as the tube axis direction (see, for example, Patent Document 2).
JP 2003-265990 A (page 2, specification paragraph 0002)

  In such a coating method using the spray gun 10, as shown in FIG. 8 and FIG. 9A, the coating films v formed with a constant width (tube axis direction width) w along the tube axis direction. However, it overlaps with the fixed axis | shaft x in the pipe-axis direction, and forms the overcoat part r. The overcoated portion r appears as a striped pattern (spiral stripe in FIG. 8) in appearance. This is because the film thickness of the paint in the overcoating portion r becomes thicker than the film thickness d of the paint in other parts, and the film thickness is uneven on the outer peripheral surface of the tube p (FIG. 9B). )reference).

If such an overcoating portion r is present, extra paint is used, so that a loss of material is caused, and the application to the overlapped portion has a lot of loss in the painting time process.
Moreover, it is not preferable that such an overcoated portion r appears as a striped pattern because the aesthetic appearance of the tubular body is impaired.

Furthermore, in general, when painting with a spray gun, if the spray pattern of the nozzle is an ellipse in plan view, among the paint discharged from the nozzle, the paint on both ends of the major axis in the major axis direction is coarse. It is difficult to disperse.
For this reason, a so-called “tail t” is generated at both ends of the spray pattern in the major axis direction, and the coating film v at the “tail t” portion tends to be thicker than the coating film v at the center of the spray pattern (FIG. 10). (See (a) and (b)).
Since the position of the “tail t” is included in the overcoating portion r in the spiral coating film v, the film thickness of the coating applied to the outer peripheral surface of the tubular body p is further uneven. End up.

  Therefore, the present invention uses a spray gun provided with a nozzle having an oval spray pattern in a plan view when coating the outer peripheral surface of a tube body, and the major axis direction of the ellipse is the same as the tube axis direction. In the case of coating toward the surface, it is an object to reduce the waste of the paint due to the overcoating portion between the coating films and improve the aesthetic appearance.

  As a first means for solving the above-mentioned problem, the present invention provides a coating film as the spray pattern of the spray gun, as the spray pattern of the spray gun forms an elliptical shape in the plan view, at both ends in the major axis direction. A coating method using a spray pattern having a gradually decreasing portion in which the minor axis width of the oblong shape or the ellipse gradually decreases, and in the coating of the outer peripheral surface of the tubular body, the gradually decreasing portion is included in the overcoat portion It was adopted.

If the overcoating part is formed by overlapping and painting parts where the thickness of the coating film or the minor elliptical width of the ellipse gradually decreases, the film thickness of the overcoating part and other parts Difference can be reduced.
The gradually decreasing portion may be configured such that the entire length or part of the major axis in the major axis direction coincides with the entire length in the tube axis direction of the overcoating part, You may make it comprise a part. Further, as the configuration of the gradually decreasing portion in the spray pattern, the thickness of the coating film in the spray pattern may be gradually decreased, or the short elliptical width of the ellipse in the spray pattern is gradually increased. It is good also as a structure which decreases. Furthermore, as a configuration of the gradually decreasing portion, a configuration in which the film thickness of the coating film in the spray pattern gradually decreases and the width of the ellipse in the minor axis direction gradually decreases may be combined.

As a second means, the present invention employs a so-called “tailless tip” as a tip attached to the nozzle of the spray gun. With the “tailless tip”, it is difficult to cause “tail” at both ends of the spray pattern in the major axis direction, and unevenness of the coating film thickness on the outer peripheral surface of the tube can be suppressed.
As the “tailless chip”, a known chip can be used. For example, a chip having a wide-angle injection pattern of 60 degrees or more in the major axis direction as shown in FIG. 11 can be used. . If the spray pattern of the “tailless tip” has a wider angle with respect to the major axis direction, the interval between the overcoating portions in the tube axis direction can be widened, which can contribute to an improvement in aesthetics.

  In addition, in the configuration in which gradually decreasing portions are provided at both ends in the major axis direction of the spray pattern, if a `` tailless tip '' is adopted in combination, in reducing the difference in film thickness between the overcoated portion and other portions, Good results can be obtained.

  In each of the above configurations, it is possible to employ a configuration in which the spraying direction of the coating material with respect to the outer peripheral surface of the tube body by the spray gun is slightly inclined along the relative movement direction of the spray gun and the tube body. Specifically, the center line for the major axis direction in the spray pattern is such that the discharge direction of the paint by the spray gun faces the direction in which the surface to be coated of the tube approaches the spray gun. A configuration that is set to be inclined with respect to a direction perpendicular to the tube axis direction of the body may be employed.

  As described above, the spray pattern in which the film thickness of the coating film or the width of the major axis in the minor axis direction gradually decreases toward both ends at the both ends in the major axis direction of the spray pattern having an elliptical shape in plan view as described above. If the “tailless tip” is used, the paint near the both ends in the major axis direction of the spray pattern is atomized finely. By this atomization, in the vicinity of both ends in the major axis direction, the ejection moment when the paint is ejected is lower than in the past. For this reason, the discharged paint tends to be easily affected by wind pressure and airflow.

  Therefore, if the discharge direction of the paint by the spray gun is tilted in the above direction, the influence of the wind pressure and airflow can be suppressed.

Further, as described above, the pipe outer peripheral surface coating apparatus used for the method of coating the outer peripheral surface of the pipe body performed by inclining the discharge direction of the paint by the spray gun, the following configuration can be adopted.
That is, a spray gun provided with a nozzle for discharging paint in a spray pattern having an elliptical shape in plan view, and a tube body can be placed and rotated by a driving force to rotate the tube body around the tube axis. And a means for moving the tube body and the spray gun relative to each other in the tube axis direction, and the spray gun has a long axis direction of the oblong shape in the spray pattern of the tube axis of the tube body. The spraying direction of the paint by the spray gun is opposed to the direction in which the coated surface of the tube approaches the spray gun with respect to the major axis direction in the spray pattern. The center line is set to be inclined with respect to a direction orthogonal to the tube axis direction of the tube body.

Further, in the above configuration, the spray gun may be supported so as to be rotatable along the tube axis direction, and the inclination of the center line may be adjusted by the rotation.
If the inclination of the center line can be adjusted, the optimum coating film can be formed by adjusting the inclination according to the coating conditions such as the speed of relative movement, the discharge strength of the paint, the surrounding air current, etc. It can be formed and applied to the outer peripheral surface of the pipe with a uniform film thickness and a beautiful appearance.

  Further, when the tube body and the spray gun are relatively movable in both directions in the tube axis direction, if the inclination of the center line can be automatically adjusted according to the relative movement direction, Since the pipe or spray gun can perform painting while repeating reciprocating motion, the time required to return the device to the starting point of painting can be reduced, and painting of the outer peripheral surface of the pipe can be performed efficiently in a short time. Can be done.

  Since this invention was made as mentioned above, it can reduce the waste of the paint by the overcoating part of coating films, and can improve the beauty | look.

An embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1 (a), the pipe outer peripheral surface coating apparatus used in this embodiment can place a spray gun 10 for discharging paint toward the outer peripheral surface of the pipe body p, and the pipe body p. Rollers 1 and 1 are provided.
As shown in FIG. 2, the rollers 1 and 1 support the tube body p placed thereon, and rotate the tube body p around the tube axis by rotating by a driving force such as a motor (not shown). Can be made.

  The spray gun 10 is connected to a pump 23 via a hose 21, and the paint in the tank 25 is supplied by the pump 23 and discharged from the nozzle 11 at the tip. Reference numeral 24 in the figure is an open / close valve.

The spray gun 10 is attached to a gun transfer machine 20, and the gun transfer machine 20 is supported by a guide 22 so as to be movable in the tube axis direction. Further, the movement of the gun transfer machine 20 is controlled by driving means such as a motor (not shown).
Therefore, the spray gun 10 can move relative to the tube body p, which does not move in the tube axis direction, at a constant speed in the tube axis direction. The speed can be freely set, and the speed can be changed during the movement. It is also possible to do.

The spray gun 10 is supported by the gun transfer machine 20 so as to be rotatable along the tube axis direction. For this reason, if the spray gun 10 is rotated along the tube axis direction, the direction of the center line 4 of the spray gun 10 by the rotation, that is, the direction of the center line 4 with respect to the major axis direction q in the spray pattern 5 to be described later. It can be adjusted. The direction of the center line 4 of the spray gun 10 can be fixed so as not to move at an arbitrary adjustment position.
In FIG. 1B, the direction in which the center line 4 faces is fixed in a state where it is inclined by an angle α with respect to the radial direction of the tube body p, that is, the tube axis orthogonal direction.

  Further, as shown in FIG. 4A, the spray gun 10 is provided with a nozzle 11 having a tip 12 having a spray pattern 5 having a long oval shape in plan view. The elliptical major axis direction q is arranged so as to face the pipe axis direction of the pipe body p.

  Further, the tip 12 is a tailless tip, and has a characteristic that does not generate a tail t at both ends of the major axis direction q, and at the both ends of the major axis direction q, the distance y increases as the distance from the center of the spray pattern increases. The paint is discharged by the spray pattern 5 having the gradually decreasing portion 6 whose width in the minor axis direction gradually decreases in the range (see the first example shown in FIGS. 4A and 4B). The width in the minor axis direction of the portion excluding the gradually decreasing portion 6 is constant.

4 (c) (d), the second example shown in FIGS. 4 (c) and 4 (d) shows the coating film v in the range of the distance y as it is farther from the center of the spray pattern at both ends in the major axis direction q as the configuration of the gradual reduction portion 6. 4 is an example of the spray pattern 5 using a tailless tip of the type in which the width in the minor axis direction gradually decreases in the same distance y range. Instead of the chip 12 having the spray pattern 5), a chip 12 having this kind of spray pattern 5 may be adopted. In addition, the film thickness and the breadth direction width of the coating film v of the part except the taper part 6 are respectively constant.
At this time, the distance y in which the thickness of the coating film v in the gradually decreasing portion 6 in FIGS. 4C and 4D gradually decreases (in the major axis direction) and the width in the minor axis direction gradually decreases (in the major axis). The distance y (in the direction) is preferably completely the same as described above, but there may be some difference between the distances y and y. When there is a difference between the two distances y and y, the one having a relatively long distance can be considered as the distance of the gradual decrease unit 6.

  When the tip 12 having the spray pattern 5 shown in FIGS. 4A and 4B or the tip 12 having the spray pattern 5 shown in FIGS. 4C and 4D is used, the spray gun provided with the tip 12 is used. When the paint is continuously sprayed while relatively moving the pipe 10 and the tube p in the direction indicated by the arrow u in FIG. 4E, the sign q ′ in FIG. The cross section shown in FIG. 4F is obtained. The cross section shown in FIG. 4 (f) is continuously formed in the direction of the arrow u, that is, the same cross sectional shape is obtained in any cross section parallel to the symbol q '.

  Details of the spray gun 10 and the nozzle 11 are shown in FIG.

  The structure of the spray gun 10 is that a gun body 13 is provided with a paint chamber 13a and an air chamber 13c connected via a needle insertion hole 13e. The front end side of the paint chamber 13a communicates with the nozzle 11, and the paint chamber 13a is filled with the paint supplied from the hose 21 through the paint port 13b.

A needle 14 is inserted into the needle insertion hole 13e so as to be able to advance and retract in the axial direction. The needle 14 fits exactly in the needle insertion hole 13e, and the paint chamber 13a and the air chamber 13c are separated from each other while maintaining liquid tightness.
The front end portion 14a of the needle 14 positioned on the paint chamber 13a side has a spherical shape, and the forward end of the needle 14 causes the front end portion 14a of the spherical needle 14 to move toward the tip of the gun body 13. The valve seat can be contacted and separated.

  The nozzle 11 includes a valve seat member 11c and a tip 12, and the valve seat member 11c and the tip 12 are fastened and fixed to the tip of the gun body 13 by a nut 11a. The valve seat is constituted by a valve seat member 11c and a tapered surface 13g formed at the front end of the paint chamber 13a, and the inner diameter thereof is slightly smaller than the diameter of the front end portion 14a of the needle 14.

  Details of the chip 12 attached to the nozzle 11 are shown in FIG. In the drawing, reference numeral 12a denotes a discharge port, reference numeral 12b denotes an internal groove that leads from the valve seat to the discharge port 12a, and reference numeral 12c denotes an external groove formed over the entire length in the width direction at the tip of the chip. Show. The internal groove 12a opens to the bottom of the external groove 12c to form the discharge port 12a, and the extending direction of the external groove 12c coincides with the major axis direction q in the spray pattern 5. Further, the discharge angle β of the paint with respect to the major axis direction is a wide angle of 60 degrees or more.

  A piston plate 14b is integrally formed at the rear end portion of the needle 14 located on the air chamber 13c side. The piston plate 14b divides the air chamber 13c into two chambers in the axial direction to maintain airtightness between them, and can advance and retreat in the axial direction together with the needle 14 while maintaining the airtightness.

Further, since the spring 15 is housed between the piston plate 14b and the rear end wall 13f of the air chamber 13c, when a gas having a predetermined pressure or more is supplied from the outside into the air chamber 13c through the air supply port 13d. The piston 14b is pushed against the elastic force of the spring 15 by the atmospheric pressure, and is pushed to the right side shown in FIG. When the needle 14 is retracted, the valve seat of the nozzle 11 is opened, so that the paint is discharged from the discharge port 12a of the chip 12.
Further, when the supply of the gas of the predetermined pressure or higher is stopped and the air pressure in the air chamber 13c is lowered, the piston 14b is pushed to the left as shown in FIG. . When the needle 14 moves forward, the valve seat of the nozzle 11 is closed, so that the discharge of the paint from the discharge port 12a of the chip 12 is stopped.

  The coating method using this pipe outer peripheral surface coating apparatus will be described. First, as shown in FIG. 1 (a), the roller 1 is rotated by a driving force, and the pipe p is moved to the pipe axis by the rotation of the roller 1. Rotate around.

  Next, simultaneously with the rotation of the tube p, when the paint is discharged from the nozzle 11 of the spray gun 10 while moving the gun transfer machine 20 along the guide 22 in the direction of the arrow a in the figure, the tube A coating film v is spirally formed along the outer peripheral surface from the insertion opening 2 at one end of the body p toward the receiving opening 3 at the other end.

At this time, in the spiral coating film v, portions corresponding to both ends of the major axis direction q of the spray pattern 5 are overlapped with both ends of the major axis direction q of the adjacent coating film v with a tube axis direction width x. A spiral overcoating portion r is formed on the outer peripheral surface of the tubular body p. The rotational speed of the tube body p and the moving speed of the spray gun 10 are set in advance as such.
In the overcoat portion r, the overall length y of the gradually decreasing portion 6 in the spray pattern 5 is equal to the overall length x in the tube axis direction of the overcoat portion r as shown in FIG. Therefore, the unevenness | corrugation which may arise in the coating film v can be decreased, and the aesthetics can be improved.

Further, as shown in FIG. 1A, the spray gun 10 faces the direction in which the coated surface of the tube body p approaches the spray gun 10 as shown in FIG. The direction of the center line 4 is inclined by an angle α with respect to the radial direction passing through the tube axis of the tube body p and passing through the tube axis.
For this reason, it is possible to prevent the discharged paint from being applied under the influence of the wind pressure or the air flow and being applied to a position shifted from the position where it should be applied.

  Note that the direction of the center line 4 of the spray gun 10 may be slightly shifted from the position passing through the tube axis of the tube body p in a direction away from the tube axis.

Further, in this embodiment, since the spray pattern 5 having the gradually decreasing portion 6 using the tailless tip is adopted, normally, for example, as shown in FIG. When the paint is discharged in the radial direction, if there is a strong wind pressure or airflow in the direction of the arrow c, the paint tends to be pushed to the left in the figure. It is considered that the paint is completely atomized in the vicinity of both ends of the spray pattern 5 in the major axis direction q, and therefore there is no discharge pressure (moment of paint) against the wind pressure and the airflow in the vicinity of both ends. .
When the paint is washed away, there is a difference in the gradually decreasing state (the gradually decreasing state of the film thickness in the state before forming the overcoat portion r) at both ends of the spray pattern 5 in the major axis direction q. For this reason, if the both ends of the major axis direction q of the spray pattern 5 adjacent to each other in the tube axis direction are overlaid in this state, the film thickness of the overcoat portion r may not be uniform, or the overcoat portion r The range expands in the tube axis direction or meanders in the circumferential direction, and the appearance of the tube body p becomes extremely inferior.

  Therefore, in this embodiment, as shown in FIG. 6A, the discharge direction of the paint is inclined so as to oppose (opposite) the wind pressure and airflow in the direction of the arrow c, so that adverse effects are suppressed. Can do.

  In addition, as shown in the figure, when spraying the spray gun 10 while moving in the opposite direction from the other end receiving port 3 toward the one end inserting port 2 as indicated by an arrow b in FIG. The direction in which the spray gun 10 is tilted is also opposite to that in the above-described embodiment.

Another embodiment is shown in FIG. In this embodiment, a coating carriage 31 is employed as means for relatively moving the pipe body p rotated around the pipe axis by the rollers 1 and 1 and the spray gun 10 in the pipe axis direction. The coating carriage 31 is provided with the rollers 1, 1, and the spray gun 10 is supported on a pedestal 30 that is fixed so as not to move to a fixed point.
The coating carriage 31 can travel in the tube axis direction with respect to the tube body p. For example, the tube body p moves in the tube axis direction with respect to the spray gun 10 by traveling at a constant speed in the direction of arrow a ′ in the figure. Can move relative to each other at a constant speed. Further, like the rotation speed of the roller 1, the speed can be freely set, and the speed can be changed during the movement.

  When the tube body p is moved in the reverse direction toward the other end receiving port 3 as shown by an arrow b ′ in FIG. 7B, the spray gun 10 is moved as shown in the figure. The direction of tilting is also the opposite direction to the previous embodiment.

  An example in which the outer peripheral surface of the tubular body p is painted using the spray gun 10 having the tailless tip will be described below.

  The embodiment shown in Table 1 is a coating method in which the spray gun 10 is fixed so as not to move to a fixed point in the tube axis direction, and the tube body p is moved by the coating carriage 31 (one direction from one end of the tube toward the other end). (One-way painting).

As described above, when the tailless tip 12 is used, since the paint is surely atomized at both ends of the spray pattern 5 in the major axis direction q, there is a tendency for the discharge momentum of the paint to drop.
For this reason, by increasing the discharge pressure of the paint, a good coating film v with no tail t was obtained, particularly in the examples marked with a circle.

  In addition, the moving speed of the spray gun 10 in Table 1 is appropriately set according to the diameter of the tube body p and the tube rotation speed. For example, the diameter of the tube body p is Φ250 (mm), and the tube rotation speed is 100 (m / min). ) Can be set to 9 (m / min).

  In the example of Table 2, by reducing the diameter of the discharge port 12a of the chip 12 and conversely increasing the discharge pressure of the paint, in particular, in the example of the circle mark in the table, a good coating film in which no tail t occurs v is obtained.

  In the example shown in Table 3, the outer peripheral surface of the pipe body p having a diameter of 75 (mm) is to be painted. When the spraying direction of the paint by the spray gun 10 is tilted 15 degrees forward, that is, facing the direction in which the surface to be coated of the tube p approaches the spray gun 10, the tail t does not occur A coating film v is obtained. The evaluation when the discharge direction is the vertical direction is indicated by a circle in Table 3, but in reality, the tail t is slightly generated.

1 shows an embodiment, (a) is an overall view, (b) is an enlarged view of the main part when the direction of movement of the spray gun is reversed. Radial sectional view of the tube of FIG. The details of the spray gun are shown, (a) is an overall sectional view, (b) is a detailed view of a tip attached to the nozzle. An example of a spray pattern is shown, (a) is a plan view of the first example, (b) is a sectional view of (a), (c) is a plan view of the second example, and (d) is a sectional view of (c). (E) is a top view which shows the coating state by the example of the spray pattern of a 1st example and a 2nd example, (f) is sectional drawing of (e). Shows the coating film formation on the outer peripheral surface of the tube, (a) is a plan view, (b) is a cross-sectional view (A) (b) is explanatory drawing which shows the influence which the coating material discharged from the spray gun receives with a wind pressure or an air current The other embodiment is shown, (a) is an overall view, (b) is an enlarged view of the main part when the moving direction of the tube is the reverse direction. The perspective view which shows the state at the time of coating the outer peripheral surface of a tubular body The state of forming a coating film on the outer peripheral surface of a tubular body in a conventional example is shown, (a) is a plan view, and (b) is a cross-sectional view. The spray pattern in a prior art example is shown, (a) is a top view, (b) is sectional drawing. Detailed view of a well-known tailless tip

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Roller 4 Spray gun center line 5 Spray pattern 6 Gradually decreasing part 10 Spray gun 11 Nozzle 12 Tip (tailless tip)
12a Discharge port 13 Gun body 14 Needle 15 Spring 20 Gun transfer machine 21 Hose 22 Guide 31 Coating carriage p Tube q Longest direction r Repeat coating part t Tail v Coating film

Claims (5)

Using a spray gun 10 provided with a nozzle 11 that discharges paint in a spray pattern 5 having an elliptical shape in plan view, the major axis direction q of the long elliptical shape of the spray pattern 5 is directed in the tube axis direction of the tube p, The pipe body p is rotated around the pipe axis, and the paint is discharged by the spray gun 10 while the pipe body p and the spray gun 10 are relatively moved in the pipe axis direction. A coating film v is formed in a spiral shape along the coating pattern v. The coating film v formed in the spiral shape has a spiral shape in which portions corresponding to both ends of the spray pattern 5 in the major axis direction q overlap with each other in the tube axis direction width x. In the coating method of the outer peripheral surface of the tubular body forming the overcoat portion r,
The nozzle 11 has a gradual decreasing portion 6 in which the film thickness of the coating film v or the short elliptical width of the ellipse gradually decreases as the distance from the center of the spray pattern increases at both ends of the major diameter direction q. 5, the paint is discharged, and the gradually decreasing portion 6 is made to coincide with the overcoat portion r ,
A tailless tip 12 is attached to the nozzle 11 of the spray gun 10, and the tailless tip 12 has an outer groove 12 c formed at the tip of the tailless tip 12 in the width direction of the tailless tip 12, and the outer groove 12 c. And an inner groove that opens to the bottom of the tube to form the discharge hole 12a, and the spray pattern 5 is formed with the width direction of the tailless tip directed toward the tube axis of the tube body p. How to paint the outer peripheral surface of the body. Using a spray gun 10 provided with a nozzle 11 that discharges paint in a spray pattern 5 having an elliptical shape in plan view, the major axis direction q of the long elliptical shape of the spray pattern 5 is directed in the tube axis direction of the tube p, The pipe body p is rotated around the pipe axis, and the paint is discharged by the spray gun 10 while the pipe body p and the spray gun 10 are relatively moved in the pipe axis direction. A coating film v is formed in a spiral shape along the coating pattern v. The coating film v formed in the spiral shape has a spiral shape in which portions corresponding to both ends of the spray pattern 5 in the major axis direction q overlap with each other in the tube axis direction width x. In the coating method of the outer peripheral surface of the tubular body forming the overcoat portion r,
The nozzle 11 has a gradual decreasing portion 6 in which the film thickness of the coating film v or the short elliptical width of the ellipse gradually decreases as the distance from the center of the spray pattern increases at both ends of the major diameter direction q. 5 is intended to discharge the paint, including Me its tapering portion 6 to the recoating portion r,
The center line 4 with respect to the major axis direction in the spray pattern 5 is such that the spray direction of the paint by the spray gun 10 faces the direction in which the surface to be coated of the tube body p approaches the spray gun 10. tube outer peripheral surface coating method of you, characterized in that inclined with respect to a direction orthogonal to the tube axis direction of the body p are set. Using a spray gun 10 provided with a nozzle 11 that discharges paint in a spray pattern 5 having an elliptical shape in plan view, the major axis direction q of the long elliptical shape of the spray pattern 5 is directed in the tube axis direction of the tube p, The pipe body p is rotated around the pipe axis, and the paint is discharged by the spray gun 10 while the pipe body p and the spray gun 10 are relatively moved in the pipe axis direction. A coating film v is formed in a spiral shape along the coating pattern v. The coating film v formed in the spiral shape has a spiral shape in which portions corresponding to both ends of the spray pattern 5 in the major axis direction q overlap with each other in the tube axis direction width x. In the coating method of the outer peripheral surface of the tubular body forming the overcoat portion r,
A tailless tip 12 is attached to the nozzle 11 of the spray gun 10, and the spray pattern 5 is formed by the tailless tip 12 .
The center line 4 with respect to the major axis direction in the spray pattern 5 is such that the spray direction of the paint by the spray gun 10 faces the direction in which the surface to be coated of the tube body p approaches the spray gun 10. tube outer peripheral surface coating method of you, characterized in that inclined with respect to a direction orthogonal to the tube axis direction of the body p are set. The pipe body outer peripheral surface coating method according to claim 2 , wherein a tailless tip 12 is attached to a nozzle 11 of the spray gun 10, and the spray pattern 5 is formed by the tailless tip 12. 5. A pipe outer peripheral surface coating apparatus for use in the pipe outer peripheral surface coating method according to claim 2, wherein the nozzle 11 discharges the paint with a spray pattern 5 having an oblong shape in plan view. A spray gun 10 provided with a roller 1, 1 that can mount the tube body p and can rotate the tube body p around the tube axis by rotating with a driving force, and the tube body p. Means for relatively moving the spray gun 10 in the tube axis direction, and the spray gun 10 is arranged so that the major axis direction q of the elliptical shape in the spray pattern 5 is directed to the tube axis direction of the tube body p. The spray pattern 10 is arranged so that the direction in which the spray gun 10 discharges the paint faces the direction in which the surface to be coated of the tubular body p approaches the spray gun 10. Center line 4 for direction, tube outer peripheral surface for painting apparatus characterized by being set inclined with respect to a direction orthogonal to the tube axis direction of the tubular body p.

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