JPH0422871Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an air doctor coater for applying paint to a web such as paper or film.

<Prior Art> Coating devices have been implemented that apply paint to the surface of a web and measure the thickness of the paint by blowing air. FIG. 2 shows an example, in which a paint receiver 1a is used as the application means 1.
After applying paint to the surface of the web 2 from a color roll 1c whose outer periphery is partially immersed in the paint 1b, the running direction of the web 2 is raised by a back-up roll 3, and the web is 2
By spraying air 5 at a required downward angle α as shown in FIG. 3 using a metering nozzle 4 provided in the width direction of I'm trying to let it form. In the figure, 8 is a catch pan for receiving excess paint 6 and using it again.

Note that the application means 1 is not limited to the applicator roll method, but may be of other methods.

<Problems to be solved by the invention> In the air doctor coater configured as described above, a portion of the air 5a that is blown onto the coated surface and reflected.
is attracted by the air flow 5 near the outlet of the metering nozzle 4, forming a circulating vortex as shown by the dotted line arrow in FIG. Since the air 5a contains scattered paint, a part of it is transferred to the tip 4 of the metering nozzle 4.
It is attached to the lower surface of a as shown in FIG. 3 and 9.

This adhered paint 9 dries and becomes hard, and if it peels off intermittently and hits the coated surface with the air flow 5, it may cause defects on the coated surface, or the hardened adhered paint 9 grows and narrows the nozzle gap. This may cause turbulence in the airflow 5 and cause streak-like defects on the coated surface. Therefore, the operator must always be careful about dirt on the tip, and if it becomes dirty, it is necessary to stop the machine and clean it, which reduces operability.

<Purpose of the invention> The present invention was devised in view of the problems of the prior art, and by providing an auxiliary nozzle that blows air to the lower surface of the tip of the metering nozzle, it is possible to prevent paint from adhering to the lower surface of the tip of the metering nozzle. The purpose of the present invention is to provide an air doctor coater with improved operability.

<Means for Solving the Problems> In order to achieve the above object, the air doctor coater of the present invention includes a coating means for coating the lower surface of a traveling web, and a coating device that wraps the web coated by the coating means and stands up from the side. A back-up roll that moves upward, a metering nozzle that scrapes off excess paint by spraying an air stream at a required downward angle onto the web running on the back-up roll, and a metering nozzle located below the metering nozzle that scrapes off excess paint. In the air doctor coater, which includes a container pan for receiving the applied paint, an auxiliary device is provided below the metering nozzle and communicates with the metering nozzle through a small hole to cause a part of the air in the metering nozzle to flow out along the lower surface of the metering nozzle. It is characterized by being equipped with a nozzle.

<Function> An auxiliary nozzle is attached to the lower surface of the metering nozzle, and by blowing the air flow from the auxiliary nozzle to the lower surface of the tip of the metering nozzle, the vortex 5a shown by the dotted line arrow in Figure 3 is blown away, thereby eliminating the vortex. Alternatively, even if a vortex remains, the vortex does not come into contact with the lower surface of the tip of the metering nozzle, thereby preventing paint from adhering to the lower surface of the tip. At this time, since the auxiliary nozzle is communicated with the metering nozzle through a small hole, the flow rate of the air flow from the auxiliary nozzle is smaller than that of the air flow from the metering nozzle, and the air flow from the auxiliary nozzle is lower than that of the metering nozzle. It is possible to prevent adverse effects on the air flow from the metering nozzle.

<Example> An example of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of the main parts of the air doctor coater of the present invention. In Fig. 1, 3 is a back-up roll, 4 is a metering nozzle, 4a is a metering nozzle tip, 4b is a small hole, 4c is an auxiliary nozzle plate, 4
d is the tip of the auxiliary nozzle plate, 4e is the slit-like space of the auxiliary nozzle, 5 is the air flow from the metering nozzle, 8 is the catty pan, and 10 is the auxiliary nozzle. Since the present invention relates to an improvement of the metering nozzle portion of the conventional air doctor coater shown in FIG. 2, in FIG. 1, the same parts as in FIG.

The auxiliary nozzle 10 will be mainly explained below.

As shown in FIG. 1, a large number of small holes 4b are bored in the lower surface of the metering nozzle 4 at required intervals in the width direction. Further, an auxiliary nozzle plate 4c is attached to the lower surface of the metering nozzle so as to cover the small hole 4b, and an opening toward the tip of the metering nozzle is provided between the tip 4d of the auxiliary nozzle plate 4c and the lower surface of the metering nozzle. A slit-like gap 4e is formed.

Next, the effect will be explained.

Compressed air is sent into the metering nozzle 4 from a blower (not shown), and is maintained at a pressure of approximately 0.1 to 0.6 kg/cm ² G. A portion of the compressed air sent to the metering nozzle 4 passes through a number of small holes 4b to the auxiliary nozzle 1.
Flows into 0. The compressed air that has flowed into the auxiliary nozzle 10 flows out through a slit-shaped gap 4e formed near the tip 4d of the auxiliary nozzle plate 4c. Air flow 10 passing through the gap 4e
Air a flows along the lower surface of the metering nozzle 4 and merges with the air flow 5 from the metering nozzle at a point slightly away from the metering nozzle tip 4a. Note that the air pressure inside the auxiliary nozzle 10 is much lower than the pressure inside the metering nozzle because the compressed air is throttled by the small hole 4b, and the flow rate of the air flow 10a is also much lower than the flow rate of the air flow 5 from the metering nozzle 4. Therefore, the airflow 10a does not disturb the airflow 5.

The airflow 10a from the auxiliary nozzle 10 blows away the vortex 5a shown by the dotted arrow in FIG. 3, or even if it cannot be blown away.
Since the lower surface of the metering nozzle 4 is purged by the air flow 10a, the vortex 5a is caused by the metering nozzle tip 4a.
There is no contact with the lower surface, and therefore paint does not adhere to the lower surface of the metering nozzle tip 4a.

<Effects of the invention> As described above, the air doctor coater of the invention has the following effects.

(1) An auxiliary nozzle is provided at the bottom of the metering nozzle to allow the airflow along the bottom surface to flow out, which prevents paint from adhering to the bottom surface of the tip of the metering nozzle, reducing the chance of defects occurring on the coated surface. do.

(2) There is no need to stop the coater to clean the paint attached to the lower surface of the tip of the metering nozzle, improving the operability of the coater.

Since the auxiliary nozzle is communicated with the metering nozzle through a small hole so that a part of the air in the metering nozzle flows out from the auxiliary nozzle, there is no need for a special air source for the auxiliary nozzle, and the auxiliary nozzle By communicating with the metering nozzle through a small hole, it is possible to adjust the velocity of the air flow flowing out from the auxiliary nozzle by adjusting the speed of the air flowing out from the metering nozzle with a simple structure and without requiring any adjustment means. It can be maintained at a moderately slower rate than the flow rate,
It is possible to prevent the airflow from the auxiliary nozzle from adversely affecting the airflow from the metering nozzle.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main parts of the air doctor coater of the present invention, FIG. 2 is a side view of a conventional air doctor coater, and FIG. 3 is an enlarged explanatory view of the measuring section. DESCRIPTION OF SYMBOLS 1... Coating means, 2... Web, 3... Backup roll, 4... Measuring nozzle, 4b... Small hole, 8... Catching pan, 10... Auxiliary nozzle.

Claims (1)

[Scope of utility model registration request] A coating means 1 for applying the paint 1b to the lower surface of the running web 2, a back-up roll 3 for wrapping the web 2 coated by the coating means 1 and running it so as to raise it from the side, and a top of the back-up roll 3. It consists of a metering nozzle 4 that sprays an air flow 5 at a required downward angle onto the web 2 running on the web 2 to scrape off excess paint, and a catch pan 8 located below the metering nozzle 4 to receive the scraped paint. In the air doctor coater, the lower side of the metering nozzle 4 is communicated with the metering nozzle 4 through the small hole 4b, and a part of the air in the metering nozzle 4 is directed toward the metering nozzle tip 4a along the lower surface of the metering nozzle 4. An air doctor coater characterized by being provided with an auxiliary nozzle 10 for discharging water to the air.