JPH0367745B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting clogging of a nozzle orifice when a fluid is discharged from the nozzle orifice in the form of smoke, and a spray nozzle directly used in the method. In particular, the present invention relates to a method for detecting clogging of a nozzle orifice when applying an adhesive liquid to a fiber web in atomized form, and a spray nozzle directly used in the method.

BACKGROUND OF THE INVENTION Conventionally, one method for manufacturing nonwoven fabrics has been to apply an adhesive to a fiber web using a spray nozzle. In this case, dust, polymers, additives, etc. in the adhesive liquid passing through the spray nozzle, or corrosive substances in the piping, deposited on the nozzle orifice easel and caused nozzle clogging. Partial or total nozzle clogging causes a change in the amount of adhesive applied, resulting in a drawback that a nonwoven fabric with a uniform amount of adhesive cannot be obtained. This defect causes a decrease in the strength of the nonwoven fabric or causes delamination.
Another disadvantage is that the coating condition is poor and the surface of the fiber web is disturbed. At present, where nozzle clogging is detected visually, detection of nozzle clogging is delayed, and the above-mentioned drawbacks cannot be promptly resolved.

For this reason, as an automatic nozzle clogging detection device, there is known a device as described in, for example, Japanese Unexamined Patent Publication No. 55-5721. This method uses a pressure gauge to detect the water pressure inside the spray nozzle, and detects nozzle clogging when the pressure difference reaches a predetermined value. This method has few problems when using a fluid with relatively low viscosity and low viscosity change, such as water, but for example, when using a fluid made of a polymer that has high viscosity and has a large viscosity change due to temperature changes. cannot be used for Because diameter 0.2
This is because when a highly viscous fluid is discharged from a nozzle orifice easer as fine as mm, a change in viscosity cannot be detected even if a partial blockage occurs. Further, if the viscosity changes due to the ambient temperature, this will cause a pressure change even when the valve is not closed, resulting in erroneous detection.

Also, as an automatic detection device for nozzle clogging,
There is also one described in the -167060 publication.
This involves inserting an optical fiber inside the nozzle to detect clogging of the nozzle orifice. This method also poses no problem if the fluid is transparent like water and does not contain deposits, but if the fluid is colored or contains substances that can become deposits, such as ordinary polymer liquids, it may cause problems. cannot be used. That is, the optical fiber may be contaminated or a high molecular weight polymer may be deposited on its light receiving portion, making it difficult to detect external light.

As a result of various studies, the present inventor found that when a fluid passes through a nozzle orifice easel with a constant diameter, the nozzle orifice generates a constant vibration, and that even a slight change in the diameter causes vibrations. They discovered that vibration also changes, and came to the conclusion that it is possible to detect nozzle clogging by utilizing the vibration change, leading to the present invention.

That is, the present invention detects vibrations generated when a fluid passes through a nozzle orifice seat, detects a predetermined change in the vibrations, and detects clogging of the nozzle orifice seat. The present invention relates to a method and a spray nozzle that is characterized in that a vibration detector is attached to a position capable of receiving vibrations of a nozzle orifice seat used directly in the method.

The present invention will be explained below based on the drawings.

The spray nozzle according to the present invention is shown in FIGS.
It is as shown in the figure. In FIG. 5, the vibration detector 21 is embedded in an outer wall 26 surrounding the nozzle hole 25. As shown in FIG. When the fluid passes through the nozzle orifice seat 23, vibrations are generated and transmitted to the outer wall 26 surrounding the nozzle hole 25. And this vibration is detected by vibration detector 2
1 and the vibration state is transmitted to the outside through a cable 19. As the vibration detector 21 and the cable 19, recently commercially available vibration sensors can be used. Particularly in the case of the present invention, piezoelectric vibration sensors are preferred.

FIG. 6 shows a spray nozzle 1 having seven nozzle orifice seats 23. In this case vibration detector 2
1 is an outer wall 2 surrounding each nozzle orifice seat 23;
It is attached to 4.

FIG. 7 shows a spray nozzle 1 in which a vibration detector 21 is attached to a nozzle hole 25. The vibrations generated from the nozzle orifice seat 23 are transmitted to the outer wall 24 surrounding the nozzle orifice seat 23 and the outer wall 2 surrounding the nozzle hole 25.
6. Furthermore, it is also transmitted to the fluid inside the nozzle hole 25. The spray nozzle 1 shown in FIG. 7 detects the vibrations transmitted to the fluid. In the spray nozzle 1 shown in FIG. 7, it is not preferable to use solid materials such as powder or granules. This is because it is difficult to transmit vibrations compared to liquids.

A specific example of how the spray nozzle 1 according to the present invention can be used is as shown in FIGS. 1 to 3, for example, for applying an adhesive to a fiber web.

FIG. 1 shows an apparatus in which the spray nozzle 1 moves left and right at a constant speed. FIG. 2 shows an apparatus in which a large number of stationary spray nozzles 1 are arranged in parallel. FIG. 3 shows an apparatus in which a pair of spray nozzles 1 are arranged in parallel.

FIG. 4 shows an apparatus in which a pair of spray nozzles 1 are arranged in parallel, and a nozzle clogging detection device and an automatic opening/closing valve controller 18 are installed therein. This device discharges adhesive liquid from only one of a pair of spray nozzles 1. When the nozzle orifice seat 23 of the spray nozzle 1 is clogged, vibrations detected by the vibration detector 21 are input to the vibration potential converter 15. If a clogged nozzle is detected, the position of the spray nozzle 1 is displayed on the clogged nozzle position indicator 16, and the automatic opening/closing valve controller 18 is activated to prevent adhesive liquid from flowing into the spray nozzle 1 where the nozzle is clogged. The adhesive liquid flows into the spray nozzle 1 and the adhesive liquid is discharged. Therefore, even if one of the pair of spray nozzles 1 becomes clogged, the adhesive can be applied to the fiber web by using the other spray nozzle 1 without stopping production.

8 and 9 show the results of detecting the vibration of the nozzle orifice easel 1 with a vibration sensor, and recording the vibration frequency and vibration acceleration output voltage. Figure 8 is the first
As shown in the figure, a vibration detector 21 is attached to a spray nozzle 1 that moves left and right at a constant speed.
The peak 28 shown in FIG. 8 is due to the impact that occurs when turning from side to side. Nozzle clogging can be detected by observing predetermined changes in the vibration frequency waveform and vibration acceleration waveform.

FIG. 9 shows the vibration detected by the vibration detector 21 attached to the stationary spray nozzle 1 shown in FIGS. 2 and 3 and recorded. This record shows that nozzle clogging occurred temporarily, but it was immediately resolved. In FIGS. 8 and 9, nozzle clogging is detected by observing both the vibration frequency and the vibration acceleration output voltage, but nozzle clogging may also be detected by observing only one of them. However, it is more reliable to detect nozzle clogging by observing both.

In Figures 8 and 9, nozzle clogging is detected by chart recording, but it can also be detected by digital display. Further, a lamp or the like may be made to blink due to a certain change in the vibration frequency, or an automatic opening/closing valve controller may be activated by internal detection as shown in FIG.

Although the present invention has been explained above mainly by taking as an example the step of applying an adhesive to a fiber web in a method for manufacturing nonwoven fabric, it can be widely applied to any other uses. In addition, the fluid passing through the nozzle orifice can be applied not only to liquids such as adhesive liquid, but also to gases, powders, granules, etc.

The present invention detects nozzle clogging by detecting unique vibrations that occur when the fluid passes through the nozzle orifice seat, that is, vibrations that are essentially different from other impact vibrations, mechanical vibrations, etc. , there are fewer detection errors and nozzle clogging can be detected reliably. Therefore, even when producing a nonwoven fabric, the amount of adhesive applied is kept uniform, and a homogeneous nonwoven fabric can be produced. In other applications as well, defects resulting from nozzle clogging can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic side view of a reciprocating type single nozzle coating device, and FIGS. 2 and 3 are schematic side views of a stationary type multiple nozzle coating device. FIG. 4 is a schematic diagram of a control circuit showing an example of the spray nozzle clogging detection method according to the present invention. 5, 6 and 7 show an embodiment of the spray nozzle according to the present invention. FIGS. 8 and 9 are charts recording the output voltage and vibration frequency of vibration acceleration detected by the vibration sensor attached to the spray nozzle. Explanations of the symbols attached to each drawing are as follows. DESCRIPTION OF SYMBOLS 1... Spray nozzle, 2... Coating liquid automatic on-off valve, 3... Coating liquid supply pipe, 4... Reciprocating traveling head, 5... Reciprocating motion selector switch, 6... Traveling transmission gear, 7... Fiber Web conveyance roll, 8...
Fiber web, 9...Fume coating liquid, 10...Coating liquid filter, 11...Fiber web conveyor, 12...Coating liquid filter, 13...Fluid pulsation suppression tank, 14...Fluid transport pump, 1
5... Vibration potential converter, 16... Nozzle clogging position indicator, 17... Nozzle clogging alarm, 18... Coating liquid automatic opening/closing valve controller, 19... Coaxial cable for vibration sensor, 20... Automatic opening/closing Valve control cable, 21... Vibration detector, 22... Nozzle filter, 23... Nozzle orifice easel, 24... Outer wall surrounding the nozzle orifice easel, 25... Nozzle hole, 26... Outer wall surrounding the nozzle hole, 27... Vibration acceleration waveform when the nozzle orifice is closed, 28...
... Reciprocating traveling head impact waveform, 29 ... Vibration acceleration waveform when nozzle orifice ease is not blocked, 30 ...
Vibration frequency waveform when nozzle orifice is blocked, 3
1... Vibration frequency waveform when the nozzle orifice is not blocked.

Claims (1)

[Claims] 1. The present invention is characterized by detecting vibrations generated when a fluid passes through a nozzle orifice easel, and detecting a predetermined change in the vibrations to detect clogging of the nozzle orifice easel. How to detect clogged spray nozzles. 2. A spray nozzle characterized in that a vibration detector is attached to a position where vibrations of the nozzle orifice seat can be received.