Drip Inhibiting Glue Nozzle

Abstract

A glue dispensing nozzle has a nozzle face with an orifice and a surface tapering outwardly and downwardly of the orifice to terminate in a flat circular rim. The nozzle has a bore in which resides a spring-loaded plunger having surfaces cooperating with a valve seat in the bore to seal off the flow of glue to the orifice. An end of the plunger extends through the orifice and forwardly of the rim so as to engage a workpiece and effectively open the nozzle as the nozzle moves further toward the workpiece. When the nozzle is retracted from the workpiece, excess glue on the nozzle face is dispersed over the tapering surface and the flat circular rim to inhibit dripping therefrom.

Description

This invention relates to dispensing nozzles and particularly to work-actuated nozzles for sequentially dispensing glue onto a plurality of workpieces and for preventing dripping between dispensing operations.

In the packaging art, it is common to form and erect cases or cartons from blank material. Typically, the material is cut into appropriately shaped blanks which are scored and folded into cases. Glue is dispensed onto tabs or flaps of a partially erected case, and these members are then folded and pressed against other cooperating tabs or flaps to secure the case in its final form.

A pattern of glue is dispensed onto the case blanks by a plurality of work-actuated nozzles supported in a glue head. Such nozzles are normally screwed into the glue head and comprise bodies having an internal passage communicating with a glue source in the head. Each nozzle terminates in a flat face having a glue dispensing orifice normally closed by a spring-loaded plunger extending through the orifice and downwardly from the flat face. In operation, the head and its nozzles are lowered toward a case blank positioned beneath the head. As the head is lowered, the plungers engage the blank and, as each nozzle continues downwardly, the nozzle orifices are thereby opened to dispense glue. The head is then withdrawn while a glued blank is removed and a fresh blank is conveyed under the head.

As the head is withdrawn, each plunger is urged downwardly to close its respective nozzle orifice. Between the time the head and the nozzle face are withdrawn and the time when the plunger shuts off the glue flow, some glue flows through the orifice and down the plunger. Glue escaping during this closure time runs down the plunger and forms a drop on the plunger's end. This drop can be so large as to drip from the plunger onto a case blank or conveyor beneath the head. Such drips occur prior to proper positioning of a succeeding case blank and are thus deposited on case surfaces not intended to be glued or on the blank conveyor. Dripping is a major problem between cycles as, for example, when the operation is stopped for some period of time. These drops respectively detract from the case's appearance and can foul the carton erecting apparatus.

It has thus been one object of this invention to provide a drip inhibiting dispensing nozzle.

A further object of this invention has been to provide a drip inhibiting glue nozzle having means for dispersing glue, flowing through a nozzle orifice during closure time, over a relatively large nozzle area.

The objectives of the invention are attained by providing a shallow, concave surface in the lower end of the nozzle surrounding the glue dispensing orifice. The nozzle face comprising this surface tapers outwardly and forwardly of the orifice and terminates in a flat, circular rim. A spring-loaded plunger resides in the passage and extends through the orifice and forwardly of the rim. Surfaces on the plunger cooperate with a valve seat within the glue passage to seal off the flow of glue through the orifice.

When glue is to be dispensed onto a workpiece, such as a carton blank, the nozzle is moved toward it so that the plunger is depressed to effectively open the nozzle. After a predetermined time, the nozzle is withdrawn or lifted from the workpiece and another workpiece is moved into position. Between the time when the nozzle is lifted from the workpiece and the time when the plunger seats to seal the glue passage, some glue escapes through the orifice. Rather than run down the plunger, however, the excess glue tends to spread itself around the concave nozzle face and eventually forms a ring about the flat rim. While the total amount of glue on the rim would be sufficient to form a large drop if suspended from a small area, such as the plunger end, the glue is spread over the much larger area of the rim and does not drip therefrom.

These and other objects and advantages will become apparent from the following detailed description and drawings in which:

FIG. 1 is a cross-sectional view of a dispensing nozzle, according to the invention, in retracted position over a workpiece;

FIG. 2 is a cross-sectional view similar to FIG. 1 but showing the nozzle in a projected glue dispensing position;

FIG. 3 is a cross-sectional view similar to FIGS. 1 and 2 but showing the nozzle in a partially retracted position; and

FIG. 4 is an end view taken along lines 4-4 of FIG. 1 and omitting the plunger.

Referring now specifically to the drawings, there is shown in FIG. 1 a glue nozzle 10 according to the specific embodiment of the invention. The glue nozzle 10 includes a nozzle body 11 having external threads 12. These threads are provided so that the glue nozzle can be screwed into a gluing head (not shown) together with a plurality of similar nozzles so as to provide a preselected pattern of nozzles and, respectively, of glue dots onto a workpiece. The nozzle body 11 includes an internal and generally axial glue passage or bore 13 which communicates with a source of glue in the head. Toward the lower end of the nozzle, the bore 13 defines a valve seat 14. The bore 13 terminates downstream of valve seat 14 at an orifice or opening 15.

A valve stem or plunger 16 is disposed within the bore 13. The plunger 16 has surfaces 17 designed to cooperate with the valve seat 14 in order to seal bore 13 against the passage of glue therethrough. The plunger 16 is urged into sealing position by a spring 18. The spring 18 is positioned between the plunger 16 and a nut 19 which is screwed into the bore 13 by way of threads 20 at the upper end of the bore 13. The nut 19 has a passageway 21 therethrough for the passage of glue. An end 22 of the plunger extends downwardly from the orifice 15 so as to be capable of engaging a workpiece C and unseating surfaces 14 and 17 to allow glue to flow from the nozzle and onto the workpiece, which can be a case or carton blank or any other material to be glued.

The nozzle 10 further comprises a nozzle face which includes a tapering surface 30 and a flat rim surface 31. The surface 30 tapers outwardly and downwardly of the orifice 15 at approximately 10.degree. with respect to the plane of the orifice and terminates in the flat rim surface 31. In the preferred embodiment, the rim surface 31 is generally circular and concentric with orifice 15. In addition, the rim 31 lies in a plane which is generally parallel to the plane of orifice 15. When the nozzle is screwed into the glue head, it is normally held in a vertical position so that the plane of the flat rim 31 is generally horizontal. Of course, the surface 30 could be slightly curved rather than having a straight taper. In any event, it provides a concave surface surrounding the orifice.

It can be appreciated that the flat rim could be omitted and the concave face could terminate in a sharp circular edge. Provision of the flat rim, however, has several advantages including the provision of more area to enhance the adhering properties of the nozzle face. Also, the flat face does not mark the blank and the glue head's movement does not have to be critically controlled to avoid blank marking or cutting.

By way of example, the preferred embodiment includes a nozzle thirteen-sixteenths inches in length. The orifice has a one-eighth inch diameter. The flat rim 31 is concentric with the orifice, is approximately 0.015 inch in width and is approximately 0.250 inch in outside diameter. The nozzle face tapers upwardly and outwardly from the flat rim and terminates in a hexagonal configuration comprising six flats 33, opposite ones of which are about one-half inch apart.

In a normal case-preparing operation, a plurality of nozzles such as the one shown in the drawings are screwed by way of their external threads 12 into a gluing head such that the passages 21 and bores 13 of the nozzles communicate with a source of glue in the head. In a typical gluing apparatus, four or five glue nozzles are positioned within the head such that when actuated they apply a pattern of four or five glue dots to a case blank disposed beneath the head. Of course, any number of nozzles could be used as required. The head is mounted to reciprocate downwardly toward the blank so that the plunger end 22 and the rim 31 of the nozzle actually engage the blank C, as in FIG. 2, and dispense glue thereon.

Since the end 22 of the plunger extends beyond the rim 31, it engages the blank C and stops while the nozzle body continues downwardly against the plunger spring bias. The glue passage thus is opened to allow glue to flow into the cavity formed by the blank C on the bottom and the dome or tapering surface 30 of the nozzle face on the top. When the nozzle is raised, a uniform dot of glue remains on the blank.

After a predetermined time, the head is reciprocated upwardly, to the position shown in FIG. 1, and the glued blank is removed while another blank is conveyed into proper glue-receiving position. The head is normally operated in the range of 8-35 cycles per minute so that the operation has an output of 8-35 cases per minute. Typically, the apparatus may be operated to handle 30 cases per minute wherein the cases dwell under the glue head for glue application for one second and during another second a glued case is removed and a new blank positioned under the withdrawn or retracted head.

FIG. 3 illustrates a glue nozzle in an intermediate position as it is raised from case blank. In this position, it can be seen that the rim 31 does not engage the case blank but the end 22 of the plunger 16 still engages the blank C so that the plunger surface 17 does not engage the valve seat 14. As a result, some glue is transmitted through the valve and the orifice 15 to the nozzle face. When the apparatus is operated at a speed of, for example, 30 cases per minute, the glue valve is normally open approximately one-sixth of a second from the time the rim first disengages the case blank until the time plunger end 22 is lifted from the blank so that the plunger surface 17 engages the valve seat 14. While this time varies, depending upon the speed at which the glue head lifts the nozzle, some finite amount of glue always escapes the valve and resides on the valve face. This excess glue tends to spread itself about the tapered surface 30. Some of the glue eventually gathers on the flat rim 31 in the form of a ring as in FIG. 3. Since the glue is dispersed over a relatively large surface area including the tapered surface and the flat rim, as contrasted with that of the plunger end 22, surface tension between the glue and the surfaces is sufficient to maintain the glue thereon and it does not drip off.

When the head is again reciprocated downwardly toward a succeeding blank, as shown in FIG. 2, the rim 31 contacts the blank and any excess glue thereon remaining from the previous application is deposited onto the blank. Thus, over a period of successive operations at a given speed, the amount of excess glue, left on the nozzle face when it is retracted from a blank, is generally the same and it is deposited on the succeeding case blank in the operation. This effectively prevents an excessive accumulation or build-up of glue on the nozzle face and the glue does not run down the plunger stem to form a large drop which could fall off onto a case or the conveyor beneath the glue head, and thus foul the apparatus.

Should the apparatus be stopped for a relatively long period of time, most of the excess glue will eventually gather on the flat rim. Due, however, to the relatively large surface area of the rim the glue is normally effectively dispersed and will not drip.

Although the preferred embodiment of the invention has been described as applied to a work actuated nozzle, the invention has equal advantageous features in other types of nozzles as can be appreciated.

While we have described herein the preferred embodiment of the invention, many other objects and advantages will become readily apparent to those of ordinary skill in the art without departing from the scope of the invention, and the applicant intends to be bound only by the appended claims.

Claims

Having described my invention, I claim:

1. Apparatus for applying glue to objects and including a glue nozzle having a body, a vertical bore in said body terminating in an orifice at the lower end thereof, and a plunger reciprocably mounted in said bore and seating adjacent said orifice to control the flow of glue through said orifice, the improvement comprising a shallow concave surface surrounding said orifice at the lower end of said nozzle to minimize dripping or residual glue from said nozzle after each gluing operation, said plunger extending through said orifice and forwardly of said concave surface so that when said nozzle is moved toward an object said plunger engages said object to unseat.

2. Apparatus as in claim 1 wherein said shallow concave surface extends outwardly and downwardly from said orifice and terminates in a flat circular rim.

3. Apparatus as in claim 2 wherein said orifice lies in a first plane and said surface tapers downwardly from said plane at approximately a 10.degree. angle with said plane.

4. Apparatus as in claim 2 wherein said orifice lies in a first plane and wherein said rim lies in a second plane parallel to said first plane.

5. Apparatus as in claim 4 wherein said plunger extends outwardly from said nozzle and beyond said second plane.

6. Apparatus as in claim 5 wherein said rim contacts said object when said nozzle is moved further toward said object and wherein said rim thereafter disengages from said object when said nozzle is moved away from said object and prior to both disengagement of said plunger from said object and seating of said plunger in said bore.

7. Apparatus as in claim 6 wherein glue is dispensed from said orifice between the time when said rim disengages from an object and the time when said plunger disengages from the object so as to seat in said bore.

8. Apparatus as in claim 7 wherein said dispensed glue is dispersed over said concave surface and forms a ring on said flat rim.

9. Apparatus as in claim 2 wherein said orifice has a radius and wherein the width of the tapering nozzle face between the orifice and the rim is approximately equal to said radius.

10. Apparatus for applying glue to objects and including a glue nozzle of the type having a body, a vertical bore in said body terminating in an orifice at the lower end thereof, and a plunger reciprocably mounted in said bore and seating adjacend said orifice to control the flow of glue through said orifice, the improvement comprising a shallow concave surface surrounding said orifice at the lower end of said nozzle to minimize dripping of residual glue from said nozzle after each gluing operation, said shallow concave surface extending outwardly and downwardly from said orifice and terminating in a flat circular rim, said plunger extending beyond said rim so that when said nozzle is moved toward a workpiece said plunger engages said workpiece to unseat as said nozzle moves toward said workpiece.

11. Apparatus as in claim 10 wherein said rim engages said workpiece when said nozzle is moved further toward said workpiece and thereafter said rim disengages from said workpiece when said nozzle is withdrawn and prior to disengagement of said plunger with said workpiece.

12. Apparatus as in claim 11 wherein glue is dispensed from said orifice between the time when said rim disengages from a workpiece and the time when said plunger disengages from the workpiece so as to seat in said bore.

13. A glue nozzle as in claim 12 wherein said dispensed glue is dispersed over said concave surface and forms a ring on said flat rim.