JPH0721242Y2 - Pipe inner surface coating machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an improvement of a pipe inner surface coating machine used for coating a coating film on a pipe inner surface.

<Prior Art> When anticorrosion coating is applied to the inner surface of a metal tube, the metal tube is heated, the heated metal tube is rotated about the tube axis, and the nozzle is moved from one end of the tube to the other end of the tube. In some cases, the inner surface of the pipe is coated with the powder to paint injected from the nozzle by rotating the nozzle about the pipe axis. 8th
The figure shows a conventional gun in such a pipe inner surface coating machine,
The angle θ'of the paint guide surface 50 'of the nozzle 5'is constant along the circumferential direction of the nozzle, and the paint from the feeder tube 1'is agitated at the angle θ'and by the rotation of the nozzle 5'. While being ejected toward the inner surface of the pipe.

In the above pipe inner surface coating, the coating thickness is regulated by the relative rotation speed of the nozzle and the pipe, the relative movement speed of the nozzle and the pipe in the pipe axial direction, the paint discharge amount, etc. This leads to uneven thickness.

<Problems to be Solved> However, in the conventional coating machine, the injection angle of the nozzle is constant, and as shown by w ′ in FIG. Since the variation of the coating thickness is relatively narrow and the variation of the above-mentioned requirements per one rotation of the nozzle occurs within the relatively narrow coating width, the variation of the coating thickness is large. Therefore, under such a large variation in coating film thickness, it is not possible to achieve uniform film thickness.

An object of the present invention is to provide a pipe inner surface capable of sufficiently reducing non-uniformity of coating film thickness even if the relative rotational speed or axial movement speed of the nozzle or the amount of coating material discharge varies. To provide a coating machine.

<Means for Solving the Problems> A pipe inner surface coating machine according to the present invention has a nozzle at a tip of a feeder pipe for injecting paint from a feeder pipe toward the inner surface of a pipe to be coated in a trumpet shape, and the nozzle is a feeder. In a coating machine that moves back and forth while rotating relative to the pipe to be coated with the pipe axis as the axis, the injection angle formed by the paint guide surface of the nozzle and the axis is continuous along the circumferential direction of the nozzle. The configuration is characterized by changing to.

<Description of Embodiments> Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1A is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 1B.
FIG. 3B is a sectional view taken along line bb in FIG. 1A. In FIGS. 1A and 1B, 1 is a paint feeder tube, which is rotatably supported by a moving stand 2 in a cantilever state. 3 is a motor and 4 is a conductive belt. Reference numeral 5 is a nozzle attached to the tip of the feeder by a support arm 6, and the paint injection angle θ formed by the paint guide surface 50 and the feeder tube shaft 10 advances left and right in the nozzle circumferential direction with one point on the nozzle outer circumference as the origin. Is changing over time. Reference numeral 7 indicates a metal pipe as a pipe to be coated.

In order to coat the inner surface of the pipe with the coating machine of the present invention, the pipe 7 is rotated about its pipe axis (for example, the pipe is supported by an underroll and the underroll is driven to rotate), and at the same time the stand 2 is moved. The nozzle 5 is reciprocally moved into the tube 7 by means of which the nozzle 5 is rotated by the rotation of the feeder tube 1, and the paint (powder coating) from the feeder tube 1 is rotated.
Is guided toward the inner surface of the pipe while being guided by the guide surface 50 of the rotating nozzle 5. Width of inner surface is applied by a rotation of the nozzle is wider width ranging between the coating position P ₂ at the coating position P ₁ and the maximum exit angle theta ₂ in the minimum emission angle theta ₁ shown in FIG. 1 A w. Therefore, the fluctuation of the paint discharge amount,
Even if there is a fluctuation in the relative rotation speed of the nozzle to the tube or a fluctuation of the relative axial movement speed of the nozzle to the tube, the change in coating thickness due to these fluctuations can be dispersed in the above wide coating width. Therefore, the change in coating film thickness per unit coating area can be sufficiently reduced.

The relationship between the change in the ejection angle along the circumferential direction of the nozzle 5 (Y axis) and the left and right circumferential phase (X axis) in the above-described embodiment is XY.
The coordinates are shown in FIG. As shown in FIGS. 4A and 4B, the emission angle change cycle can be shortened. FIG. 3A is a perspective view of a nozzle whose ejection angle changes in the pattern of FIG. 4A, and FIG. 3B is a perspective view of a nozzle whose ejection angle changes in the pattern of FIG. 4B. The center of the nozzle coincides with the axis of rotation, and there is no blur even when rotating at high speed, which is advantageous for high-speed rotation. The injection angle is usually selected within the range of 90-40 °. Maximum exit angle is 90
As the nozzle of °, it is also possible to use a disk that is bent in half in a V shape at a predetermined angle (minimum injection angle). As shown in FIG. 5A, two plates 51 and 52 are attached to the nozzle 53 with a pin 53.
Alternatively, as shown in FIG. 5B, a paint reflecting plate 54 may be provided in the center of the nozzle 5 and the paint that reflects the reflecting plate may be guided and ejected on the inner surface of the nozzle. For rotation of the nozzle, instead of rotation of the feeder tube 1, for example, as shown in FIG. 6, a large gear 81 is rotatably mounted on the feeder tube, the nozzle 5 is supported on the large gear, and a motor is used. 82 is attached to the feeder tube 1, and the motor shaft 83
The small gear 84 may be meshed with the large gear 81, and the motor 5 may rotate the nozzle 5. Further, instead of moving the feeder tube in the pipe axis direction, the pipe to be coated may be moved in the pipe axis direction.

Next, the coating state when the inner surface of the pipe is coated by the inner pipe coating machine according to the present invention will be described in comparison with the case where a conventional machine is used.

(When using the machine of the present invention) The paint used is nylon paint, and the discharge amount is 400 g.
/ min. A steel pipe having an inner diameter of 200 mm and a length of 2000 mm was used as the pipe to be coated, and the rotation speed was 20 rpm. The nozzle rotation speed is 300 rpm, and the nozzle axial movement speed is 7 m / min.
The number of coatings was set to 4 (two reciprocations). The shapes of the nozzles used were a flower-shaped section (I type) shown in FIG. 4A and an eyebrows-shaped section (II type) shown in FIG. 4B, and the maximum ejection angle θ ₂ was 7
0 ° and the minimum emission angle θ ₁ were 50 °.

On the other hand, when the conventional machine is used, the nozzle whose ejection angle along the circumferential direction is constant at 70 ° is used, and the other conditions are the same as those when the machine of the present invention is used. did.

In each of the above cases, the coating thickness on the inner surface of the pipe every 200 mm is as shown in Fig. 7. When using the conventional machine, the coating thickness is not uniform, but when using the machine of the present invention, It is much more uniform than when using conventional machines.

<Effect of the Invention> As described above, in the pipe inner surface coating machine according to the present invention,
Since the paint injection angle of the nozzle is changed along the circumferential direction of the nozzle, the coating width per nozzle rotation can be widened, so there is sufficient change in film thickness per unit area due to changes in coating conditions during one nozzle rotation. It can be made extremely small and the coating thickness can be made uniform. Moreover, the structure is simple because it is only necessary to change the injection angle of the nozzle in the circumferential direction.

[Brief description of drawings]

FIG. 1A is an explanatory view showing an embodiment of the present invention, FIG. 1B is a sectional view taken along the line bb in FIG. 1A, and FIG. 2 is an explanation showing a change state of an injection angle of a nozzle in the embodiment. FIGS. 3A and 3B are explanatory views showing another example of the nozzle used in the present invention, and FIGS. 4A and 4B are injection of the nozzles of FIGS. 3A and 3B, respectively. FIG. 5A, FIG. 5B, and FIG. 6 are explanatory views showing other examples of nozzles used in the present invention, and FIG. 7 is a coating machine of the present invention. FIG. 8 is an explanatory view showing a coating film state on the inner surface of the pipe, and FIG. 8 is an explanatory view showing a conventional example. 1 …… Feeder tube, 5 …… Nozzle 50 …… Paint guide surface, θ …… Injection angle

Claims (1)

[Scope of utility model registration request] 1. A nozzle for ejecting paint from a feeder tube toward the inner surface of the coating tube in a trumpet shape is provided at the tip of the feeder tube, and the nozzle is relatively to the coating tube with the axis of the feeder tube as an axis. In a painting machine that moves back and forth while rotating,
A pipe inner surface coating machine, characterized in that an injection angle formed by the paint guide surface of the nozzle and the above-mentioned axial center continuously changes along the circumferential direction of the nozzle.