JP2592317B2 - Dispensing failure detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a coating failure detecting device for detecting a coating failure of a web (long photosensitive material) coated on both sides simultaneously without contact during continuous running of the web. It is about.

[Conventional technology]

In the photoreceptor coating process of a web, which is a long photographic photoreceptor material, it is important to detect coating failures such as streaks and unevenness as early and as accurately as possible from the viewpoint of reducing the product loss rate. In particular, although the necessity is great in the simultaneous application process on both surfaces, there have been various technical difficulties. In other words, it is relatively easy to detect a coating failure when the coating surface is completely dry, but a large number of defective products are generated due to a delay in the failure detection. In addition, since the surface of the web to be levitated and conveyed must be monitored in a non-contact manner, the restriction is large. Therefore, conventionally, as shown in FIG. 4, a non-contact type failure detection sensor 7 is provided near the web 2 continuously running between the two gas ejection cylinders 3 and 3 'in the dryer portion of the coating surface to detect a defective portion. The coating failure device 1 to be monitored was configured.

[Problems to be solved by the invention]

Although the above-mentioned conventional apparatus has a minimum condition for detecting a failure without damaging the web immediately after coating, the web conveyed by levitating is greatly displaced by a subtle change in the transport condition, and is not suitable for failure detection. There was a problem that it could have a serious adverse effect.

That is, the web is displaced due to fluctuations in transport conditions such as the pressure of the gas supplied to the gas jetting cylinder, the web tension, the coating speed, the coating film thickness, and the web thickness, and the detection accuracy is reduced. However, there was a case where a secondary failure that caused contact with the web occurred. For this reason, these transport conditions are constantly monitored, and the air pressure supplied to the jet cylinder, especially for the gas having a large influence, is adjusted as needed to stabilize. However, this adjustment requires skill during the coating operation, and the occurrence of trouble due to an adjustment error cannot be avoided. It is an object of the present invention to provide a coating failure detection device that can transport a web in a substantially constant state without performing such complicated adjustments and can always realize stable and high-precision failure detection.

[Means for solving the problem]

In order to achieve the above object, the present invention relates to a coating failure detecting device provided with a coating failure sensor between two gas ejection cylinders capable of floating and supporting a continuously conveyed web with ejection gas, provided on a surface of the gas ejection cylinder. 2% hole opening rate
In the following, the holding angle of the web holding surface is set to 90 degrees or more, and gas resistance ribs are provided along the width direction of the web at the web introduction part and the lead-out part of the web holding surface, and the transport conditions vary slightly. Even if there is, the flatness of the web is maintained, and the detection sensor is not adversely affected.

〔Example〕

Hereinafter, the present invention will be described based on an embodiment shown in the accompanying drawings.

FIG. 1 is a plan view showing the overall structure of the present invention, FIG. 2 is a perspective view showing the structure of a gas ejection tube, and FIG. 3 is a plan view showing the positional relationship between a web and a gas ejection tube in another embodiment. is there.

In the figure, reference numeral 1 denotes a main body of the coating failure detecting device according to the present invention. Reference numeral 2 denotes a web. The web 2 is simultaneously coated on both sides by a coating apparatus (not shown), and then continuously conveyed while receiving a certain tension, and then transferred to a drying step.

Reference numerals 3 and 3 'denote gas jetting cylinders. The jetting cylinders 3 and 3' jet gas toward the web 2 from jet holes F (or slits) provided at appropriate positions on the surface thereof so that the web 2 can be floated and supported. It is configured. In the present embodiment, the gas jetting cylinders 3 and 3 'are formed using inexpensive vinyl chloride pipes which are easy to process. The ejection tube 3 is provided on the upstream side with respect to the transport direction of the web 2, and the ejection tube 3 ′ is provided on the downstream side, and a web holding surface 5 described below is provided on each surface so as to face the surface of the web 2 at a predetermined holding angle θ. Is provided (FIG. 2).

The size of the holding angle θ is determined by the relative positional relationship between the ejection cylinders 3 and 3 ′ and the web 2.
It is desirable that it be ゜ or more. For this reason, the ejection cylinder 3,
The arrangement of 3 'and the web 2 is shown in FIG.
To (d), the holding angle θ for each is θ
= 90 ° (a), (b), 90 ° <θ <180 ° (c), θ = 1
80 ゜ (d). Here, the holding angle θ is
Although only an example of a symmetrical arrangement that is the same between the jetting cylinders 3 and 3 'is shown, an asymmetrical arrangement in which the holding angle θ differs between the ejection cylinders 3 and 3' may be adopted as long as the condition for stable conveyance is satisfied.

Reference numeral 4 denotes a flatness maintaining means provided on each of the gas jetting cylinders 3 and 3 '. The maintaining means 4 comprises a web holding surface 5 and gas resistance ribs 6a and 6b. The web holding surface 5 is a surface for floatingly supporting the web 2 with gas ejected from the ejection holes F toward the surface of the web 2, and has an opening ratio K (=) for enhancing the floating stability of the web 2. (Total open area / surface area of web holding surface) is 2.0% or less, more preferably 1%
It is as follows. The pressure P of the gas supplied to the ejection cylinders 3 and 3 'depends on the web transfer conditions such as the embracing angle θ, the web tension, and the coating thickness, but is usually set to be slightly higher than P = 200 mmAq, preferably about 500 mmAq. It is desirable to do.

The cross-sectional shape of the gas resistance ribs 6a and 6b is an inverted U-shape, and is resistant to airflow during exhaust. However, the cross-sectional shapes of the ribs 6a and 6b are triangular, quadrangular, semicircular, circular, polygonal,
For example, the shape may be any shape, and the dimensions of each part may be appropriately changed. Further, the cutout is not necessarily uniform in the width direction of the web, and a cutout may be provided at an appropriate position. Gas resistance rib
The material of 6a and 6b may be an elastic body such as metal, plastic, Al alloy, and rubber.

Reference numeral 7 denotes a non-contact coating failure sensor provided at an appropriate position in the vicinity of the web 2 that continuously travels between the ejection tubes 3 and 3 '. The sensor 7 transmits or reflects infrared rays to the web 2 to detect a coating failure in a non-contact manner. I can do it. The sensor 7 is
In the case of the transmission type as in this embodiment, the web is arranged so that both sides of the web are sandwiched between the light emitting and receiving sections.

The web 2 and the web holding surface 5 contain the above-described high-pressure static gas in the form of a film, and this static gas is rapidly increased to the external pressure at the web introduction section A and the web exit section B. When the web 2 is opened, the pressure is rapidly reduced, which may promote the flapping phenomenon of the web 2. The gas resistance ribs 6a and 6b are for preventing such a flapping phenomenon, and the introduction section A and the exit section B are provided.
Are provided so as to be parallel to the width direction of the web 2.

In general, the relationship between the web and the gas jetting cylinder for floating the web is such that the gas supply pressure is P ₁ , the average static pressure (cushion pressure) between the web and the web holding surface is P ₂ , and the radius of the holding surface is r.
Assuming that the web tension is T and the opening ratio is K, the static pressure P ₂ is the tension T
And inversely proportional to the radius r. Further, the flying height d of the web with respect to the holding surface is proportional to the amount of air flowing between the web and the holding surface, that is, the product of the amount of air V to the jetting cylinder and the opening ratio K. And
To avoid contact between the web and the holding surface, the radius of the holding surface r
There is an idea that it is preferable to take a larger value and make the flying height d larger. In that case, the opening rate K
Largely taken (e.g. 5% or more), large air volume V, often reduce the supply pressure P _1. As a result, the ratio of the supply pressure to the average static pressure = P ₁ / P ₂ becomes smaller. However, in such a system, when P ₂ changes according to the fluctuation of the web tension T, the change is calculated as P ₁ / P ₂ Can not be absorbed, which leads to a change in the flying height d.

Therefore, in the present invention, the flying height d is as small as 2 mm or less, and P
So that the value of ₁ / P ₂ is increased, the supply pressure P ₁ is greater in the ejection tube, the supply air volume to the opening ratio K and ejection tube is made smaller, to stabilize the static pressure state I have.

By reducing the porosity of the web holding surface, the static pressure between the web and the web holding surface was stabilized, an extremely rigid air layer was formed, and the change in the flying height due to the change in web tension was almost eliminated. . Further, by providing the gas resistance rib, it is possible to suppress the exhaust air of the gas in the web traveling direction and not to disturb the static pressure state, so that the generation of the vibration of the web can be greatly suppressed from a high frequency to a low frequency.
In addition, since the static pressure between the web and the web holding surface is made uniform in the width direction of the web, it is difficult to generate “crews” that can be parallel to the web traveling direction, and the web transport state is further stabilized.

(Experimental Example) In order to conduct an experiment of the flatness maintaining means of the coating failure detecting device of the present invention, as shown in Table 1, the present inventors found that the opening ratio of the web holding surface was extremely small as compared with the conventional device. Thus, a coating failure detection device including a gas ejection cylinder having a large ejection pressure was constructed.

Next, when the failure detection performance of this device was compared with that of the conventional device, an expected good result was obtained in which the amount of web displacement could be stabilized without adjusting the supply air pressure (Table 2).

[Effects of the Invention] As described above, the present invention provides a coating failure detection device provided with a specific contact failure detection sensor in the vicinity of a web running continuously between two gas ejection cylinders. The gas outlet ribs have a spout opening rate of 2% or less, the hugs of the web holding surfaces are 90 ° or more, and the gas resistance ribs are provided along the width direction of the web at the web introduction portion and the outlet portion of the web holding surface. Is provided, a high-pressure static gas present in the form of a film between the web and the web holding surface acts as a resistor at the web introduction portion and the outlet portion and does not escape to the outside. The floating amount of the web is stabilized, and the vibration of the web due to the airflow fluctuation is reliably eliminated.
Therefore, the flatness of the web is maintained, the detection conditions of the application detection sensor are stabilized, and highly accurate failure detection is possible.

As a result, high accuracy of coating failure detection, trouble reduction,
Various excellent effects such as labor saving of adjustment work, improvement of product yield, and improvement of productivity by stable production are exhibited.

[Brief description of the drawings]

FIG. 1 is a plan view showing the overall structure of the present invention, FIG. 2 is a perspective view showing the structure of a gas ejection tube, FIG. 3 is a plan view showing the positional relationship between a web and a gas ejection tube in another embodiment, 4th
FIG. 1 is a plan view showing the entire configuration of a conventional coating failure detection device. DESCRIPTION OF SYMBOLS 1 ... Application failure detection apparatus main body 2 ... Web 3, 3 '... Gas ejection tube 4 ... Flatness maintaining means 5 ... Web holding surface 6a, 6b ... Gas resistance rib 7 ... Non-contact application failure sensor A: Web introduction part B: Web lead-out part F: Jet hole

Claims (1)

(57) [Claims] In a coating failure detection device provided with a non-contact failure detection sensor in the vicinity of a web running continuously between two gas ejection cylinders, an opening ratio of an ejection port provided on a surface of the gas ejection cylinder is 2%. % Or less, the holding angle of the web holding surface is 90 degrees or more, and gas resistance ribs are provided along the width direction of the web at the web introduction portion and the lead-out portion of the web holding surface. Dispensing failure detection device.