GB2153709A

GB2153709A - A gluing nozzle for a packaging machine

Info

Publication number: GB2153709A
Application number: GB08500406A
Authority: GB
Inventors: Rene Delacretaz
Original assignee: Sapal SA
Current assignee: Sapal SA
Priority date: 1984-02-06
Filing date: 1985-01-08
Publication date: 1985-08-29
Also published as: DE3501174A1; CH654539A5; GB8500406D0; GB2153709B; DE3501174C2

Abstract

A gluing nozzle having a spring-biassed valve needle (9) for releasing glue on demand from a chamber (8), wherein the end of the nozzle is surrounded by a sleeve (14) which defines an open outer glue application chamber (15). The needle is surmounted by a rod (16) which extends beyond the top of the outer chamber (15). <IMAGE>

Description

SPECIFICATION A gluing nozzle, particularly for a packaging machine The present invention relates to a gluing nozzle, particularly for a packaging machine, comprising a body in which there is formed a glue chamber containing a valve for releasing, on demand, some of the glue contained in this chamber.

Packaging machines in which packaging material is to be glued are generally equipped with at least one gluing nozzle with a ball-valve which is pressed on the surface to be coated with glue resting on a rigid support known as a gluing counter-element, to enable the ball to be retracted, the valve opened and the glue held under pressure to flow through the aperture formed between the ball and its seat.

When the glue is to be deposited spotwise, the gluing nozzle, which is generally disposed vertically beneath the material to which glue is to be applied, is caused to come to rest sequentially against the gluing counter-element. From time to time the packaging machine may continue to run when it is temporarily empty of products to be packaged or packaging material, as a result of various interruptions in flow which are known per se. In this event, to prevent the machine from becoming clogged up with glue it is essential to prevent the glue from flowing when there is no packaging to be effected, and this is normally achieved either by holding back the gluing nozzle, or by providing a hole in the gluing counter-element, in which the ball is accommodated in the absence of packaging material.

However, these known methods have disadvantages, especially since the mass of the gluing nozzle is considerable and its displacement speeds are high, which makes it difficult to hold this component back. In the absence of a gluing counter-element provided with holes, it is absolutely essential to blockthenozzleto preventgluefrom being deposited. Moreover, it is known that to actuate the ball and cause the glue to flow out of the body of the nozzle it is essential to control the path of this nozzle very precisely, since this path has to be less than the distance between the apex of the ball and the apex of the body of the nozzle, thus in the region of three to fourtenths of a mm.

To solve this problem gluing counter-elements are being adopted at the present time which are provided with a number of holes corresponding to the number of gluing nozzles. These holes should have a diameter which is greater than the diameter of the body of the nozzle at its upper end to allow the head of the nozzle to penetrate into the hole in the gluing counter-element, if necessary, in the absence of packaging material. These relatively large holes are the source of another disadvantage: the risk of deforming the packaging material if it is particularly flexible, and if its resistance is is insufficientto withstand the pressure exerted by the ball of the gluing nozzle without being permanently deformed.

Finally, spotwise gluing also poses the problem of the quantity of glue deposited on each cycle. If, when gluing with lines of glue, a sufficient amount of glue is deposited on each cycle to ensure satisfactory gluing of heavy materials which are more or less rigid, such as packing card, this amount is frequently insufficient when glue is applied spotwise.

The present invention proposes to remedy the various disadvantages mentioned above by providing a gluing nozzle which enables a sufficient amount of glue to be deposited on each cycle to ensure satisfactory gluing of any kind of packaging material, and solves the problem of the precise definition of the path of the gluing nozzle, as well as that posed by the risk of deformation of the packaging material due to the large diameter of the holes in the gluing counter-element.

To this end, the gluing nozzle according to the invention is characterised in that the valve opens into an outer open chamber, and in that the obturating member of the valve is equipped with an axial rod the height of which is greater than the depth of this outer open chamber.

The present invention will be better understood with reference to the description of an embodiment and the attached drawing, on which: Figure 1 is an axial section through the gluing nozzle according to the invention, and Figure 2 is a partial perspective view of the upper part of this gluing nozzle.

The gluing nozzle shown in the Figures comprises a body 1 mounted on a support 2 and composed of a baseplate 3 and a nozzle 4 which is attached, for example by screwing, to the baseplate 3. The baseplate 3 has a cylindrical duct 9 passing through it and connected to a source of glue under pressure (not shown). An O-ring sealing joint 6 is disposed between the baseplate 3 and the nozzle 4, and a second O-ring joint is located between the baseplate 3 and the support 2, these elements preferably being assembled together by screwing.

A glue chamber 8 is formed inside the nozzle 4 above the upper part of the baseplate 3 which acts as a support for the nozzle. This chamber contains a valve of the needle valve type or similar, the element for obturating this chamber being either a needle or any other element with the same function. In the example shown this valve consists of a conical needle 9 mounted on one end of a rod 10, the other end of which is connected to a guide part 11 adapted to slide inside the duct 9 while allowing the passage of glue through central channels or axial peripheral ducts.A spring 12 which is coaxial with the rod 10 is braced at one end against the lower surface of the needle 9 and at the other end against the upper surface of the baseplate 3, to push the conical surface of the needle 9 against its seat, which is defined by an opening in the shape of a truncated cone formed through the planar wall 13 obturating the nozzle 4 at its upper end.

A cylindrical sleeve 14 surrounds the upper cylindrical end section of the nozzle 4. The height of this cylindrical sleeve is such that its upper end extends slightly beyond the level of the wall 13 so as to form, at the upper end of the gluing nozzle, a small outer chamber 19, annular in shape, which defines the shape and dimensions of the spot of glue deposited on each gluing cycle on the material on which glue is to be deposited. This chamber, which is open at its upper end and which is normally filled with glue in the molten state, is bounded laterally by the upper section of the internal wall of the sleeve 14, and at the bottom by the upper planar wall 13 of the nozzle 4, and in the centre by the needle 9.

In extension of the upper end of the conical needle 9 there is an axial rod 16, the height of which, relative to the base of the open outer chamber 15, defines the path of the needle valve and accordingly the opening of this valve.

This construction makes if possible to increase in a simple manner the path of the valve defined by the length of the axial rod 16, and to control the opening of the nozzle which determines the amount of glue delivered on each working cycle. The presence of the outer chamber filled with glue enables the surface of the zone on which glue is deposited on each cycle to be increased substantially, which facilitates the application of glue to all kinds of packaging materials, including semi-rigid or pre-stressed materials.

Finally, the presence of the axial rod 16 allows the diameter of the hole or holes in the gluing counterelement to be restricted. Thus, as the path is no longer critical, the hole in the gluing counterelement may have a diameter slightly greater than that of this rod, but considerably less than that of the head of the gluing nozzle.

The conical needle may of course be replaced by a ball connected to a rod, provided that this ball is equipped with a rod 16 such as that described above.

The nozzle 4 may display circular symmetry, but it may equally well have a straight polygonal section of one kind or another, especially a square section. In this case the open outer chamber and consequently the spot of glue will be in the shape of a ring with a polygonal periphery.

Claims

1. A gluing nozzle, e.g. for use in a packaging machine, comprising a body in which there is formed a glue chamber containing a valve for releasing, on demand, some of the glue contained in this chamber, characterised in that the valve opens into an upper outer open chamber (16), and in that the obturating member (9) of the valve is equipped with an axial rod (16) the height of which is greater than the depth of the outer chamber (19).

2. A nozzle according to Claim 1, characterised in that the open outer chamber (15) is formed above the glue chamber (8), and in that the two chambers are in communication via an opening which can be obturated by this obturating member (9) of the valve, the shape of which is complementary to that of the opening.

3. A nozzle according to Claim 2, characterised in that the obturating member (9) of the valve is mounted on a guided rod (10) which slides axially inside the glue chamber (8).

4. A nozzle according to Claim 3, characterised in that the valve comprises the obturating member (9) fixed to one end of the guided rod (10), a guiding part (11) fixed to the other end of this rod (10) and a spring (12) adapted to be braced at one end against a fixed wall of the glue chamber (8) and at the other end against the obturating member (9).

9. A nozzle according to Claims 4 and 9, characterised in that passing through the baseplate (3) there is an axial cylindrical duct (9) which is connected to a source of glue under pressure, and in which the guiding part (11) can slide.

6. A nozzle according to Claim 5, characterised in that the open outer chamber (15) is defined by the upper wall (13) of the nozzle in which the communicating aperture between the two chambers (8, 16) is formed, and by a cylindrical sleeve (14) surrounding the upper cylindrical end section of this nozzle (4).

7. A nozzle according to Claim 2, characterised in that the length of the rod (1 6) surmounting the obturating member (9) is greater, measured from the base of the open outer chamber (1 5), than the depth of this chamber.

8. A nozzle according to Claim 2, characterised in that the obturating member (9) is formed by a needle, and in that the wall of the communicating opening between the two chambers is in the shape of a truncated cone, thus forming the seat of the valve of which the needle is the movable part.

9. A gluing nozzle constructed, arranged and adapted for use substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.