Coating apparatus – Projection or spray type – With projector heating – cleaning or conditioning
Reexamination Certificate
1998-10-28
2001-05-29
Crispino, Richard (Department: 1734)
Coating apparatus
Projection or spray type
With projector heating, cleaning or conditioning
C118S024000, C118S104000, C239S112000, C156S389000, C156S578000, C134S022120, C134S022140
Reexamination Certificate
active
06238484
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a hot-melt adhesive coating machine, and more particularly, to a reactive hot-melt adhesive coating machine which applies a reactive hot-melt adhesive sprayed out of nozzles unto an applied object. The reactive hot-melt adhesive used in this machine is molten in a heated condition and curable when reacting with moisture content in ambient air.
Conventional reactive hot-melt adhesive coating machines are constructed to spray a reactive hot-melt adhesive out of a plurality of nozzles of a plurality of spray means. The reactive hot-melt adhesive is supplied from an adhesive supply means having an adhesive storage tank, which stores the reactive hot-melt adhesive in a molten condition, through an adhesive feeding passage with an appropriately pressurized air. The reactive hot-melt adhesive coating machine as constructed above has a problem that, after a coating operation with the spray means spraying out the reactive hot-melt adhesive, the reactive adhesive remaining within the nozzles is cured as a result of reacting with moisture in the ambient air, and the cured adhesive causes nozzle clogging. To avoid nozzle clogging, a known preventive measure is to saturate the heads of the nozzles in water-free oil after operation.
However, this a preventive measure for avoiding nozzle clogging requires the structure of the reactive hot-melt adhesive coating machine to have an oil tank and therefore becomes complex. Also, removing the oil from the nozzles takes substantial time. Further, the conventional apparatus still has another problem that the cured reactive hot-melt adhesive accumulated in each operation clogs the nozzles, as after each operation during the period between the end of the operation and the nozzles are saturated in the oil, a little amount of the reactive hot-melt adhesive remained at the opening of the nozzles is cured as a result of reacting with moisture in the ambient air.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing disadvantages of the prior art.
Accordingly, it is an object of the present invention to provide a reactive hot-melt adhesive coating machine which is capable of preventing clogging of nozzles by a simple structure.
It is another object of the present invention to provide a reactive hot-melt adhesive coating machine which is capable of removing a factor of a nozzle clogging by discharging a reactive hot-melt adhesive out of the nozzles after a coating operation.
A reactive hot-melt adhesive coating machine in accordance with the present invention has one or more sprayers spraying a reactive hot-melt adhesive out of a plurality of nozzles. The reactive hot-melt adhesive is molten in a heated condition and moisture curable when reacting with water content in the ambient air. The apparatus is also provided with an adhesive storage tank for storage of the molten reactive hot-melt adhesive, which is supplied from the adhesive storage tank to the nozzles of the sprayers through an adhesive feeding passage. The machine also includes a cleaning fluid storage tank for storage of cleaning fluid, which does not react with the molten reactive hot-melt adhesive to cure the molten reactive hot-melt adhesive, and is not curable reacting with ambient air or moisture content in the ambient air at a normal temperature. A cleaning fluid feeding passage through which the cleaning fluid is fed from the cleaning fluid storage tank to the adhesive feeding passage is connected to the adhesive feeding passage through a change-over valve. The change-over valve allows the reactive hot-melt adhesive to flow to the nozzles through the adhesive feeding passage and prevents the cleaning fluid from being fed from the cleaning fluid feeding passage to the adhesive feeding passage when spraying the reactive hot-melt adhesive out of the nozzles; and prevents the reactive hot-melt adhesive from being fed to the nozzles through the adhesive feeding passage, by disconnecting the adhesive feeding passage, and allows the cleaning fluid discharged out of the nozzles when cleaning the nozzles.
With the reactive hot-melt adhesive coating machine as constructed above, the cleaning fluid feeding passage is provided as a ramification on the way of the adhesive feeding passage between the adhesive storage tank and the spray means through the change-over valve, and the cleaning fluid storage tank is connected to the cleaning fluid feeding passage. In finishing the coating operation of spraying the reactive hot-melt adhesive, the change-over valve functions to connect the cleaning fluid storage tank to the spray means to supply the cleaning fluid from the cleaning fluid storage tank to the sprayers, thereby the reactive hot-melt adhesive remaining in the adhesive feeding passage downstream of the change-over valve and within the sprayers is discharged out of the nozzles by the feeding pressure of the cleaning fluid. In this step of the operation, the reactive hot-melt adhesive remaining in the adhesive feeding passage downstream of the change-over valve and within the sprayers is replaced with the cleaning fluid which does not react with water or moisture content in the ambient air. As a result, a factor a causing nozzle clogging after operation is removed. In resuming the coating operation, the change-over valve functions to disconnect the cleaning fluid storage tank from the sprayers and alternatively connects the adhesive storage tank to the spray means to supply adhesive. The adhesive comes out of the nozzles of the sprayers when the operation of spraying is resumed.
As described above, the coating machine in accordance with the present invention is capable of preventing nozzle clogging by discharging the reactive hot-melt adhesive, which causes a nozzle jamming, out of the passages of the sprayers including the nozzles after operation, and replacing with the cleaning fluid, which is not curable when reacting with the ambient air or moisture content in the ambient air at a normal temperature.
In the coating machine in accordance with the present invention, the clogging of the nozzles can be prevented in a simple structure of the apparatus as the replacement of the reactive hotmelt adhesive in the passages of the sprayers including nozzles with the cleaning fluid can be made by a switching action of the change-over valve to changeover the adhesive storage tank to the cleaning fluid storage tank.
The sprayers is arranged to spray out the reactive hot-melt adhesive out of the nozzles with appropriately pressurized air, and the cleaning fluid supply means is arranged to feed the reactive hot-melt adhesive with appropriately pressurized air and also feed the cleaning fluid by appropriately pressurized air.
The change-over valve may be a three-way valve and the cleaning fluid may be a hot-melt adhesive including non-aqueous solution or a hot-melt adhesive made of synthetic rubber. The cleaning fluid adopting a hot-melt adhesive made of such materials as described above exhibits relatively high viscosity coefficient, so as that the reactive hot-melt adhesive may be extruded out of the nozzles completely.
REFERENCES:
patent: 3348520 (1967-10-01), Lockwood
patent: 4895603 (1990-01-01), Semp et al.
patent: 5720850 (1998-02-01), Otta
patent: 5964407 (1999-10-01), Sandkleiva
patent: 9-299865 (1997-11-01), None
Crispino Richard
Gilman & Berner LLP
Hauptman Lowe
ITW Dynatec Kabushiki Kaisha
Lorengo J. A.
LandOfFree
Reactive hot-melt adhesive coating machine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Reactive hot-melt adhesive coating machine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Reactive hot-melt adhesive coating machine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2571985