Dripless Liquid Dispenser

Abstract

A dripless liquid dispenser having an inlet for receiving liquid at dispensing pressure and one or more dispensing ports through which the liquid exits from the dispenser. Each port is provided with an individual pressure-actuated valve which opens to pass liquid to the port when liquid is supplied to the dispenser inlet at normal dispensing pressure and closes to block dripping of the liquid from the port when the supply of liquid to the dispenser is Shut off. The preferred dispensing port shutoff valve is an elastic valve sleeve surrounding the communicating passage between the port and dispenser inlet and having an exit end located immediately adjacent the port which normally assumes a constricted configuration wherein the sleeve blocks liquid flow to the port.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to the field of liquid dispensing and more particularly to a novel dripless liquid dispenser.

2. Prior Art

It will become evident as the description proceeds that the present liquid dispenser may be used for various purposes. However, the invention is concerned primarily with and will be disclosed in relation to glue applicators for carton forming and sealing machines and the like.

A typical carton forming and sealing machine operates on cardboard blanks for partially formed cardboard carton structures which are folded to final carton configuration as they pass through the machine. Such cartons commonly have flaps to which glue is applied at one station of the machine. These glue-coated flaps are then folded to final position at a following station of the machine and retained in folded position until the glue sets sufficiently to form a permanent bond.

A variety of glue dispensers or applying systems have been devised for such carton-forming machines. The present invention is concerned with gluing systems of the type which embody a supply of liquid glue under pressure, one or more glue dispensers or applicators which are disposed to apply the glue to the carton surfaces to be bonded, and a solenoid valve for controlling glue flow through each applicator. In some gluing systems of this type, a single solenoid valve serves a number of glue applicators. This valve arrangement reduces the number of valves required and hence the cost of the gluing system, permits placement of the valves in readily accessible locations where they can be easily serviced, and minimizes the size of the applicators. However, the valve arrangement presents the disadvantage that relatively long glue-filled passages exist between the valve and its glue applicators. When the valve is closed, the glue within these passages tends to drain through the dispensing ports in the glue applicators. Such glue drainage, of course, is undesirable for the reason that it fouls both the machine and the cartons.

An alternative type of gluing system which alleviates this drainage problem to some degree employs solenoid valves which are embodied directly within the glue applicators. This arrangement locates the valve for each applicator in relatively close proximity to the applicator dispensing port and thereby reduces the glue drainage which tends to occur when the valve is closed. However, the cost of these combination glue applicator and solenoid valve units is relatively high. Moreover, the glue applicators, and hence their contained valves, are generally situated in locations which are not readily accessible for servicing. The applicators are also quite bulky in size. Moreover, since a typical glue applicator of this type has a number of dispensing ports and a single valve for controlling flow through all of the ports, the applicator still permits an undesirable amount of glue drainage owing to the existence of glue-filled passages of appreciable length between the valve and its respective dispensing ports.

SUMMARY OF THE INVENTION

The present invention provides a dripless liquid dispenser which is uniquely suited for use as a glue applicator. In this particular application, the dispenser or applicator possesses virtually all of the advantages of the single-valve gluing system described above and yet virtually totally eliminates the glue drainage problem. According to the present invention, this is accomplished by providing the applicator with a simple compact pressure-actuated valve for each of its dispensing ports. The valve for each port opens when the applicator is supplied with glue at normal dispensing pressure and closes when the supply of glue to the applicator is shut off. The flow-operating means of each valve are located directly adjacent its corresponding dispensing port. Accordingly, no appreciable glue drainage, if any, occurs through the dispensing ports when the main dispensing valve is closed.

The preferred pressure-actuated valve for each dispensing port is an elastic valve sleeve surrounding the communicating passage between the port and the applicator inlet. The exit or downstream end of this valve sleeve is located directly adjacent its respective dispensing port and normally assumes a constricted configuration in which the passage through the valve is constricted to block flow to the port. When glue is supplied to the applicator at normal dispensing pressure, the pressure of the glue acts internally of the valve sleeve to expand or open its constricted end and thereby permits the glue to pass through the sleeve through the dispensing port. The applicator is uniquely constructed to facilitate cleaning and replacement of the individual dispensing port valves, when necessary.

As noted earlier, while the invention is primarily concerned with glue applicators, it may be utilized for dispensing other liquids.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a carton forming and sealing machine embodying glue applicators according to the invention;

FIG. 2 is an enlarged view of one of the applicators looking in the direction of the arrows on line 2--2 in FIG. 1;

FIG. 3 is an end view of the dispenser taken on line 3--3 in FIG. 2;

FIG. 4 is an enlarged section through the applicator taken on line 4--4 in FIG. 2;

FIG. 5 is a further enlarged perspective view of one of the individual dispensing port valves embodied in the applicator; and

FIG. 6 is an end view of the port valve.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The drawings illustrate an improved liquid dispenser 10 according to the invention which, in this instance, is a glue applicator for a carton-forming machine 12. The applicator has a body 14 which is split, along a parting plane P, into two mating sections 14a, 14b. These body sections are joined by bolts 15. Extending through the body is a passage 16 defining an inlet 18 and a manifold 20 within the rear body section 14a and a number of branch passages 22 within the front body section 14b terminating in dispensing ports 24. The inlet 18 and branch passages 22 extend normal to and open through the parting faces of their respective body sections 14a, 14 b. The manifold 20 intersects the inlet at right angles and opens laterally through the parting face of the rear body section. The dispensing ports 24 extend at oblique angles from the forward ends of the branch passages 22 and open through a rounded exterior work-engaging surface 26 on the front body section 14b.

Contained within each branch passage 22 is a pressure-actuated valve 28 for the adjacent dispensing port 24. Each illustrated port valve 28 is an elastic valve sleeve surrounding the respective branch passage. Downstream or exit end 30 of the valve sleeve assumes a normal constricted or flattened configuration, shown in FIG. 5, when flow of glue to the applicator inlet 18 is cut off. In this flattened configuration, the valve sleeve constricts the passage through the sleeve to block glue flow to the adjacent dispensing port 24. It will be observed that the exit end of each valve sleeve is located immediately adjacent its dispensing port, and the port is a small-diameter vein or passage. Accordingly, virtually no drainage through the port occurs when glue flow to the applicator is cut off. When glue is supplied to the applicator inlet at normal dispensing pressure, the pressure of the glue acts internally of each valve sleeve 28 to expand or open its constricted exit end, as shown in FIG. 6, to permit glue flow to the adjacent dispensing port.

Surrounding the upstream or inlet end of each dispensing port valve sleeve 28 is a flange 32. The inlet end of each branch passage 22 is counterbored to receive this flange. Accordingly, when the applicator body sections 14a, 14b are assembled, the valve sleeves are firmly retained in position within the branch passages of the applicator. The valve sleeves may be easily removed for cleaning or replacement, when necessary, by separating the body sections.

The present glue applicator may be installed in a variety of carton-forming machines and in any position in such machines. In the machine of FIG. 1, the applicators are installed in inclined attitudes, for example. The applicators are placed so that their dispensing ports 24 open toward the carton surfaces to be bonded when the cartons travel past the applicators. The several applicators are connected to a pressurized glue supply (not shown) through conduits 34 and a main glue supply valve (not shown). This supply valve is actuated by each carton approaching the gluing station. When thus actuated, the supply valve opens to feed glue at normal dispensing pressure through the applicators. The several dispensing port valves 28 in each applicator are open by glue pressure to permit glue flow from the inlet to the applicator dispensing ports 24. When the supply valve closes to shut off glue flow to the applicators, the port valves reclose, i.e., return to their normal constricted configurations, to block glue drainage to the dispensing ports.

Claims

What is claimed as new in support of Letters Patent is:

1. A dripless glue dispenser for applying liquid glue to a workpiece comprising:

a body having a surface for contacting said workpiece, and a glue passage providing a valve chamber, a glue inlet opening to one end of said chamber for receiving liquid glue under pressure, and a dispensing port extending from the other end of said chamber through said body surface for dispensing said glue onto said workpiece, and

a resilient valve sleeve within said valve chamber sealed at one end to said body at said one chamber end and having a tip at the other chamber end which assumes a constricted configuration to cut off glue flow to said dispensing port when the glue flow to said inlet is cut off and opens to pass glue to said port when said inlet receives glue under pressure.

2. A glue dispenser according to claim 1 wherein:

said body is split into mating body sections in a parting plane transverse to and intersecting said one chamber end,

means joining said body sections, and

said valve sleeve has a flange about said one sleeve end which is clamped between said body sections to seal said valve sleeve to said body.

3. A dripless glue dispenser for applying liquid glue to a workpiece comprising:

an elongate body having a longitudinal surface for contacting said workpiece and glue passage means providing a number of valve chambers spaced along said body, a manifold extending along said body and opening to one end of said chambers, a glue inlet opening to said manifold for receiving glue under pressure, and dispensing ports extending from the opposite ends of said chambers through said body surface at positions spaced therealong for dispensing glue to said workpiece, and

a resilient valve sleeve within each valve chamber sealed at one end to said body at said one end of the respective chamber and having a tip at the other chamber end which assumes a constricted configuration to cut off glue flow to the respective port when the glue flow to said inlet is cut off and opens to pass glue to the respective port when said inlet receives glue under pressure.

4. A glue dispenser according to claim 3 wherein:

said body is split into mating sections in a parting plane transverse to and intersecting said one end of said chambers,

means joining said body sections, and

each valve sleeve has a flange about its one end which is clamped between said body sections to seal the respective sleeve to said body.