JPH0570504B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a distribution-controlled spray nozzle for spraying paint used for painting the inner surface of cans, and a spray device using the spray nozzle.

(Prior Art) In the can manufacturing process, the inner surface of the can is coated to prevent corrosion caused by the contents. In the case of two-piece cans, the inner surface is painted by spraying paint onto the inner surface of the can, which is held on its side by a turret and rotates at a constant speed, using a spray nozzle held at a fixed position on the outside. I'm going. The spray nozzle of the spray device is required to have a spray pattern that provides a nearly uniform coating thickness on the inner surface of the can body. It is known that a boat-shaped or almost triangular pyramid-shaped notch is formed that expands at the front, and a boat-shaped or isosceles triangular orifice is formed at the part where the ridgeline intersects with the cylindrical hole. (Japanese Unexamined Patent Publication No. 50-70915, Japanese Utility Model Publication No. 55-37248).

These paint distribution curves using conventional nozzles (obtained by spraying paint onto upright corrugated paper in a short period of time with the nozzle's longitudinal axis oriented horizontally) show some variation as shown in Figure 8. Although there are variations, the maximum flow point P in the main body is located near one end of the nozzle longitudinal axis. By setting the position of the nozzle so that the side of the maximum flow point P is on the bottle side of the can body, the inner surface of the can can be coated to a uniform thickness. However, in actual painting, it is impossible to obtain a coating film with a uniform thickness using the conventional nozzle, and generally the 9th
As shown in the figure, when the entire inner surface of a can is coated simultaneously with one nozzle 21, the distribution of coating film thickness on the can body is as follows:
As shown in FIG. 10, the coating film thickness in the area A near the can opening and the area C near the bottom end becomes thinner, making it impossible to apply uniformly. Therefore, conventionally, as shown in FIG. 11, separate nozzles 21,
A so-called two-spray gun system is adopted in which spraying is performed using 23 cylinders. However, even in this case, it is not possible to obtain a uniform coating thickness up to the area A near the opening. The coating thickness of the can body obtained by these conventional coating methods is 1
In the case of a spray gun, as shown in Figure 10, the area near the opening and the bottom area are approximately 1.5 μm, and the intermediate area B is 3 to 4 μm.
In the case of 2 spray gun method, the area A near the opening is approximately 1.5μ
m, and other areas B and C are 3 to 4 μm,
The coating near the opening is thinner than other parts.

(Problems to be Solved by the Invention) In the can manufacturing process, after painting the inside of the can, a flange is applied to the opening end to tighten the can lid, and in the case of a net-in can, a netting process is also performed. I'm going. These processes forcibly bend the vicinity of the can opening end (hereinafter referred to as the trim part), which may cause the paint film to peel off or
It becomes easier to get hurt. However, cans (especially 2-piece cans) coated with the conventional nozzle
As mentioned above, even if the paint film on the trim part is thick enough to prevent corrosion, the paint film on the trim part is thinner, so the paint film on the trim part may be damaged by these processes. If the paint is not durable enough, the paint film may break in that area and corrosion may occur. Therefore, conventionally, in order to obtain a coating thickness that can withstand these treatments, the amount of paint sprayed is increased to increase the overall coating thickness, and the trim part is used to spread the coating film as much as possible within the distribution curve. The direction of the nozzle must be adjusted so that the nozzle is positioned in the opposite direction. As a result, more paint than necessary is applied to areas other than the trim area, consuming a large amount of paint, and at the same time, the paint sprayed from the nozzle may cause overspray areas as shown in Figures 9 and 11. As E becomes wider, more paint is sprayed outside the can opening end, and more paint is wasted. Moreover, there were drawbacks such as the paint adhering to the main body of the device and staining the device. Furthermore, the conventional cans obtained thereby had problems such as not being able to obtain a sufficient coating thickness on the trim portion, and corrosion occurring from that portion.

The present invention was devised in view of the above-mentioned circumstances, and it is possible to make the coating thickness of the trim part thicker than other parts, and to ensure the minimum necessary coating thickness of the other parts. It is an object of the present invention to provide a spray nozzle and a spray device that can spray paint efficiently and without waste.

(Means for Solving the Problems) In order to achieve the above object, the present inventor conducted various studies on the shape of the nozzle, and found that the distribution of coating film thickness on the inner wall of the can body The present invention was achieved by discovering a nozzle shape that has a distribution curve that increases the thickness.

That is, a nozzle hole is formed in the nozzle body, the tip of which is a dome-shaped blind end, and the rear end is open, and a boat-shaped or triangular pyramid-shaped notch that expands forward is formed as the dome-shaped blind end. The above problem was solved by forming a boat-shaped or approximately isosceles triangular orifice-type jet nozzle that intersects the two, and by providing arc-shaped notches near both ends of the orifice.

Furthermore, by combining the above-mentioned nozzle and a restrictor having a pre-orifice with an opening area that is 1/2 to 2 times the ejection opening area of the spray nozzle and attaching it to the tip of the spray gun body, A spray device with an ideal distribution curve was obtained.

(Operation) With the nozzle having the above configuration, a distribution curve whose basic shape is shown in FIG. 4 was obtained. As is clear from the figure, while securing the maximum flow rate near one end in the longitudinal axis direction of the nozzle, the other end area also does not rapidly decrease as in the conventional case, and the constant flow rate Q immediately starts from the end area. is ensured. The reason why such a distribution curve is obtained is that the maximum flow rate region is formed in the notches 8, 8 near the triangular base of the jet nozzle, and the flow rate Q in the other end region is in the notches 7, 7. (See Figure 2). In addition, when combined with a restrictor, a paint distribution curve was obtained in which the maximum flow range was more acutely directed toward the bottom while maintaining the above characteristics, as shown in FIG. Therefore, when painting the inner surfaces of two pieces using a distribution-controlled spray nozzle with these distribution curves, a constant flow of paint is sprayed immediately from the can opening, so a large amount of paint is sprayed on the trim part near the nozzle injection port. of the paint will be sprayed, and the paint film on the trim part will be thicker than on other parts, and the desired paint film formation will be obtained.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

1 and 2 show an embodiment of the spray nozzle 1 according to the present invention, which has a substantially cylindrical nozzle hole 4 whose base end is open in the nozzle body 2 and whose other end is a dome-shaped blind end 3. At the same time, a triangular pyramid-shaped notch 5 that expands forward is crossed with the dome-shaped blind end 3, so that the apex 9, 10, 11 is approximately located on the inner circumferential circle of the nozzle hole 3. An isosceles triangular or approximately boat-shaped orifice-type spout 6 is formed. Further, arcuate notches 7, 7 and 8, 8 are formed near both ends of the orifice 2 on equal sides. These notches can be formed from the inside of the nozzle hole 3 by appropriate means such as wrapping with a tapered needle or electric discharge machining.
It is important to leave portions 10 and 11 in place in order to prevent the formation of tails that tend to appear at both ends of the spray pattern.

The spray nozzle 1 of this embodiment has the above configuration, and is used by being attached to the tip of the spray gun body using a nozzle adapter. However, in order to more reliably prevent the occurrence of tails, it is necessary to It is better to provide a pre-orifice. FIG. 3 shows a state in which a restrictor with a pre-origin is provided and attached to a spray gun. In the figure, 1
2 is a restrictor, and a pre-orifice 13 is formed in the center. The pre-orifice 1
It is desirable that the opening area of No. 3 is about the same as that of the nozzle ejection port 6, but if it is in the range of 1/2 to 2 times that amount, the tail prevention effect can be achieved. 14 is a spray gun body, 15 is a nozzle adapter for attaching the spray nozzle 1 and restrictor 12 to the spray gun body, and is composed of a nozzle case 16 and a retaining nut 17.

Using the nozzle of the above embodiment configured as described above, at a paint pressure of 20 kg/cm ² and a spray distance of 20 cm,
When a paint distribution curve was determined using the method described above, a shape as shown in FIG. 4 was obtained. Furthermore, the paint distribution curve when the restrictor is provided is the fifth
The results shown in the figure were obtained. As is clear from these figures, according to the nozzle of this example, the eighth
Compared to the conventional type shown in the figure, the flow rate increases immediately, especially near the end opposite to the maximum flow rate region.

Then, this nozzle is used for coating the side walls of the can body in combination with another nozzle for coating the bottom of the can body, and the can inner surface paint is applied to the two-piece can at a paint pressure of 20 kg/cm ² and a paint temperature of 40 kg/cm 2 .
~50℃, spray time 80~90ms, can rotation speed 1800~
As a result of spraying at 2000 rpm as shown in Figure 6,
The can body coating thickness had a distribution as shown in FIG. Note that the coating film thickness in these figures is exaggerated compared to the actual thickness. As is clear from the figure, the trim part has a thickness of about 3 to 5 μm, and the other parts have a thickness of 2 to 3 μm, and the parts other than the trim part are thinner than before, and the trim part is thicker than before.
As a result, it was possible to obtain a coating film thick enough to withstand flanging and netting processing of cans, and no damage to the coating film was found due to these processings. or,
Since the nozzle of the present invention has the above-mentioned distribution curve, as shown in Fig. 6, the overspray area is much smaller than that of the conventional nozzle, and there is no waste of paint. The amount of dirt caused by machines has decreased.

(Effects) The present invention has the above configuration and provides the following special effects.

According to the spray nozzle of the present invention, it is possible to thicken the paint film on the trim part that is susceptible to impact on the can body and thin it on other parts, and because there is less overspray, paint can be applied more dramatically than before. You can save money. And because there is less overspray, there is less chance of contaminating the equipment with paint.

Furthermore, by using it in combination with a restrictor, it is possible to more reliably prevent the occurrence of tails, and it is possible to ensure a more uniform coating film thickness in the area near the bottom of the can.

Furthermore, the can obtained by this method has a sufficient coating thickness on the trim part, so the coating will not be damaged even when subjected to netting processing, etc.
A can with excellent protection of contents can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of a main part of an embodiment of a spray nozzle according to the present invention, FIG. 2 is a front view thereof, FIG. 3 is a side sectional view of a spray device, and FIG. Fig. 5 is a paint distribution curve diagram using the apparatus shown in Fig. 3, Fig. 6 is a diagram showing the state in which a two-piece can is sprayed by the nozzle of the present invention, and Fig. 7 is a diagram of the can body obtained thereby. A conceptual diagram showing the state of the coating film. Figure 8 is a paint distribution curve diagram of a conventional spray nozzle. Figure 9 is a diagram of the state in which the inner surface of a two-piece can is coated with a single spray gun method using a conventional spray nozzle. Figure 10. is a conceptual diagram showing the state of the coating film on the can body obtained by the method shown in Figure 9, Figure 11 is a diagram showing the state of painting the inner surface of a two-piece can using a two-spray gun method using a conventional spray nozzle, and Figure 12 is a diagram showing the state of the coating film on the can body obtained by the method shown in Figure 9. FIG. 12 is a conceptual diagram showing the state of the coating film on the can body obtained by the method of FIG. 11. 1: Spray nozzle, 2: Nozzle body, 3: Blind end, 4: Nozzle hole, 5: Triangular pyramidal notch, 6:
Spout nozzle, 7, 8: notch, 9-11: corner, 12: restrictor, 13: pre-orifice, 14: spray gun body, 15 nozzle adapter.

Claims (1)

[Scope of Claims] 1. A nozzle hole is formed in the nozzle body, the tip of which is a dome-shaped blind end, and the rear end is open, and a triangular pyramid-shaped or boat-shaped notch that expands forward is formed. Crossing the dome-shaped blind end, approximately 2
A distribution control type spray nozzle characterized by forming an orifice-type spout having an equilateral triangle or a substantially boat shape, and having arc-shaped notches near both ends of the orifice. 2. A sprayer characterized in that the spray nozzle according to claim 1 is attached to the tip of the spray gun via a restrictor having a pre-orifice with an opening area that is 1/2 to 2 times the outlet area of the spray nozzle. Device.