US 3517646 A
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Description (OCR text may contain errors)
June 30, 1970 B. L- THOMAS ADHESIVE APPLICATION APPARATUS Filed April 25, 1968 lNjVENTOR/S Bum/a0 L. THOMAS ATTORNEYSI United States Patent 3,517,646 ADHESIVE APPLICATION APPARATUS Buford L. Thomas, Cincinnati, Ohio, assignor to Valco, Inc., Cincinnati, Ohio, a corporation of Ohio Filed Apr. 25, 1968, Ser. No. 724,202 Int. Cl. B05c 3/18 US. Cl. 118-411 8 Claims ABSTRACT OF THE DISCLOSURE An improved apparatus for the application of adhesive, such as glue, to cartons or containers. The improvement resides in the use of a flexible wick surrounded by a sheet of plastic, such as polytetrafluorethylene resin, and mounted adjacent the applicator head through which the adhesive or glue is applied to a moving work piece.
DEVELOPMENT OF THE INVENTION The improvement brought about by this invention was the result of a desire to avoid and overcome many of the problems associated with the prior art devices. Before considering these problems in detail, and the manner by which the present invention avoids same, it may be helpful to consider a typical prior art device which is disclosed in US. Pat. No. 3,299,854. I refer in particular to FIG. 4 wherein there is shown a wetted wick mounted adjacent the gluing applicator. The patentee suggests that wetted wicks must be used to prevent the glue remaining in the ports of the applicator head from setting and blocking the ports. In addition, the wicks serve to collect any excessive glue which might leak from these ports.
However, the desire of the prior art practitioners to solve one problem resulted in the introduction ofothers into the system. Typically, the wicks of the older devices are felt pads, which in use must be reasonably hard to prevent dried glue from sticking to the wick and the applicator head. Otherwise, the felt pads would be pulled out of the restraining rails or troughs when a carton flap passes. This was difficult, however, since the wick contains the solvent of the glue which is usually water. This is compounded by the fact that the glue is dissolved from the applicator head onto the felt. This is despite the fact that the heads have been designed so as not to leak. This results in a sticky mess, which gets onto the head and the carton flap, and may be carried along to other parts of the sealing mechanism. When enough has been accumulated, paper may be' pulled off of the carton in some later operation such as the compression section. The problems are even complicated further in installations where the heads are mounted in a vertical position. Here the leakage problem is inherent with the system as a result of the hydraulic head of glue in the applicator head. However, design attempts to eliminate the problem have merely minimized it. For example, the applicator heads were designed by increasing the surface contact of the glue in the applicator head, thereby retarding the leakage. However, with the thinner glues which are sometimes required, excessive leakage nevertheless results, particularly in the sealing operation.
It was not until the development of the present invention, that the preceding problems were overcome. The daily maintenance problems with the wetted felt pads were also eliminated by the substitution of a flexible wick covered by a sheet of plastic such as polytetrafluorethylene resin.
BRIEF SUMMARY OF THE INVENTION In the preferred embodiment of this invention, flexible pads such as soft felt, sponge rubber, polyurethane foam, or the like, is covered with a sheet of polytetrafluorethyl- "ice ene resin. This assembly is inserted in a trough or channel member mounted in the rail supporting frame of an adhesive applicator system. The applicator head is positioned adjacent the wick and is movable normal to said wick. Thus, when the applicator head is not applying glue to a carton, it will be buried in the flexible pad, thereby excluding air from the ports of the applicator head and causing the glue to dry out. Further, particularly on vertical applicator systems, the soft pad, which is pressed against the ports in the head, functions in the manner of a valve to shut off the flow of the hydraulic head of glue. This prevents leakage in the system. Finally, by the elimination of water-from the Wick assembly of this invention, any glue which remains on the sheet or applicator head will dry out. And, this will be brushed off by the container flap brushing there against, and will not be carried further onto the subsequent operation. It should therefore be apparent that the present invention has found a simple and expedient means for eliminating the problems of the prior art.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partial perspective view of an adhesive applicator system utilizing the improved invention described herein.
FIG. 2 is a sectional view taken through an adhesive applicator head and the improved wick assembly of this invention.
DETAILED DESCRIPTION OF INVENTION Turning now to a more complete description of the invention, particularly as it relates to an adhesive applicator system such as shown in FIG. 1, the apparatus diagramatically shown in FIG. 1 is arranged so as to successively move a series of cartons or containers past an adhesive applicator containing an adhesive such as glue. In a subsequent operation the cartons or containers are folded and sealed for shipment. However, to avoid problems during this later operation, and with the shipment of glued cartons, it is essential that the gluing operation be as simple and efiicient as possible. Such a system is illustrated in FIG. 1.
The illustrated adhesive applicator system comprises a conveyor 10 parallel to a set of rails 12, all of which cooperate in guiding the carton past the adhesive applying station. While it is not shown in FIG. 1, some means will generally be provided to open the carton flaps 14 so that they ride along the rails 12.
As the carton or container proceeds along the rails 12, the flaps 14 are caused to contact the adhesive applicator heads 16 where upon an adhesive such as glue is applied to the exposed sides of the flaps 14. For convenience, in FIG. 1 the applicator heads 16 are shown spaced from the rails 12. However, in operation, the applicator heads 16 are either in contact with the flaps 14 or with the wick assemblies 18. The contact between the applicator head 16 and rails 12 or wick assemblies 18 is accomplished and maintained by means of a spring (not shown) or by other means well known in the art.
FIG. 2 is a detailed sectional view showing the actual relationship of the adhesive applicator head 16 and the wick assembly 18 prior to the passage of a carton flap 14 therebetween. It will be seen from the latter figure that the wick assembly comprises a trough 20 positioned in a channel in each of said rails 12. Thus, the top of the trough 22 is coextensive with the top surface 24 of the rail 12. This arrangement permits an uninterrupted movement of the carton flap 14 past the applicator head 16. Disposed in the trough 20 of the wick assembly 18, there is provided a soft flexible pad 26 such as soft felt, sponge rubber, polyurethane. foam, or the like. Surrounding each pad 26 is a film or sheet 28 of plastic, which in the preferred embodiment is polytetrafluorethylene resin, a product sold under the trade name Teflon.
Before considering the wick assembly 18 in greater detail, it will be observed that the applicator head 16 is provided with a curved flap engaging portion 30 in which ports 32 are provided to dispense the adhesive. The applicator heads are designed in this manner to insure a smooth flow of work past the adhesive applying station, and to achieve a good contact between the applicator head and the adjacent wick. The adhesive to be dispensed through the ports 32 is received through a central bore comunicating with conduit 34. The adhesive is metered to the conduit by a suitable valve which may be triggered by any number of means well known in the art. However, it will be understood that when using viscous liquids such as glue, there will be a certain delay in operation such that the conduit 34 and ports 32 will remain filled with the glue. Thus, in the absence of a shut-off valve located in each of the ports, some means must be provided to minimize the leakage of the glue or adhesive therefrom.
The present invention accomplishes the latter purpose by utilizing the wick assembly 18 descfibed above. That is, by utilizing a film of soft, pliable, wear resistant plastic, such as polytetrafluorethylene resin, on a pad of flexible material, the applicator head 16 will be buried in this soft pad during periods when the adhesive dispensing valve is inoperative. This excludes the air from the ports 32 thus preventing the glue from drying out or even dissolving on the surface of the pad. Under the conventional wet wick, such is not possible. The present system has particular advantage in a vertically oriented gluing operation where the leakage problem has been a constant headache for the piror art.
Considering now the operation of the system shown in FIGS. 1 and 2, the carton which has been formed in the manner illustrated moves along the conveyor in the direction indicated by the arrow. During this time the applicator head 16 and wick assembly 18 are in contact such as shown in FIG. 2. However, as the carton flap 14 reaches the area of the gluing operation, some suitable triggering mechanism may be activated to release the applicator head 16 from contact with the wick assembly 18, thereby permitting the flap 14 to pass between the respective member and allowing adhesive to be dispensed through the port 32 onto the flap 14. Upon completion of the gluing operation, a further switch may be activated to reengage the applicator head 16 with the wick assembly 18. No attempt has been made herein to describe such switches as they are elements common to such a system, and form no particular part of this invention. This cycle is repeated until such time as the operation is shut down, such as at the end of a shift or over a week end. One of the advantages of the present invention becomes apparent when the operation is resumed.
The prior art wet felt pads, such as described in the patent identified above, not only require attention during the operation, but require servicing prior to the start up of operations. For example, during the operation of the apparatus, attention must be given to the pads to insure that the pans or reservoirs wetting the wicks or pads contain suflicient water or solvent to prevent the pads from drying out and becoming glued to the applicator heads. Further, unless the Wet felt pads are stored in the solvent during the shut down period, problems will arise upon resumption of the operation. None of these problems are present, however, with the dry wick assembly described in the present invention.
While the improvement herein has been described with respect to a preferred embodiment, workers skilled in the art, upon reading this specification, may find other and various applications for this invention. Therefore, no limitation is intended to be imposed on this invention except as set forth in the appended claims.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. In an adhesive applicator apparatus including an applicator head through which the adhesive is applied to a work piece moving relative thereto, and a frame member containing a rail to slidably support said workpiece, said applicator head movably mounted from a first position to a second position adjacent said frame member, the improvement comprising in combination therewith, a trough in said rail and containing a dry flexible pad, said pad being surrounded by a thin sheet of plastic, whereby said sheet and said pad yield when contacted by said applicator head in said second position.
2. The combination of claim 1 wherein the top of said trough is coextensive with said rail.
3. The combination of claim 2 wherein said applicator head is provided with a curved surface in the area through which the adhesive is applied, whereby when said applicator head contacts said sheet, said sheet will be contiguous with a portion of said curved surface.
4. The combination of claim 3 wherein said sheet encircles said pad, and each of said last named elements are slidably received in said trough.
5. The combination of claim 4 wherein said trough is provided with a flanged edge to retain the wick therein.
6. The combination of claim 5 including a second rail parallel to said first rail, and containing a trough.
7. The combination of claim 6 wherein said troughs lie transverse to the movement of the work piece, with each of said troughs containing a flexible pad surrounded by a sheet of plastic.
8. The combination of claim 1 wherein said plastic sheet is polytetrafluorethylene resin.
References Cited UNITED STATES PATENTS 3,088,433 5/1963 Walter et al 118-411 X 3,299,854 1/1967 Van Loben Sels 118-411 3,324,584 6/1967 Adiletta et al. 38140 3,374,882 3/1968 Amali-ksen 20646 3,416,491 12/1968 Turnbull et al 118411 3,432,380 3/1969 Weber 16116] X JOHN P. McINTOSH, Primary Examiner