GB2294891A

GB2294891A - Roller gumming device

Info

Publication number: GB2294891A
Application number: GB9522910A
Authority: GB
Inventors: Gianpaolo Cavazza; Claudio Mistroni; Antonio Gamberini
Original assignee: GD SpA
Current assignee: GD SpA
Priority date: 1994-11-11
Filing date: 1995-11-08
Publication date: 1996-05-15
Also published as: IT1274103B; GB9522910D0; DE19541836A1; ITBO940493A0; ITBO940493A1

Description

j 1 A 1 2294891 GUMMING DEVICE The present invention relates to a gumming

device for applying an adhesive substance to material in sheet form.

The device is advantageously used to apply sealing labels or state stamps in processing machines that operate Sin the tobacco industry, such as for example cigarette packaging machines, to which the following description will refer explicitly without thereby losing in generality.

In conventional cigarette packaging machines, state stamps are usually applied to the finished packets that leave a wrapping wheel; said stamps are taken from the bottom of a stack or are obtained by cutting a continuous strip, and are then fed along a set path that runs through a gumming device that is adapted to apply a given amount of an adhesive substance to said stamps.

is Said conventional gumming devices generally comprise a container that has a lower portion constituted by a tank for containing an adhesive substance that accommodates at least one gumming roller that is partially immersed in said tank. The gumming roller has an outer gumming surface, an upper portion of which lies outside said container and is arranged tangent to the advancement path of the state stamps.

Said container also accommodates a scraper unit, which is arranged substantially in contact with a generatrix of said gumming surface to eliminate the excess adhesive substance and obtain a uniform layer of adhesive substance on said gumming surface.

In order to apply the adhesive substance exclusively in given points or areas of the surface of the stamps, a 2 gumming roller in which the gumming surf ace is provided with grooves or indents and a scraper device to remove from said gumming surface all the adhesive substance that is not contained inside said indents are used.

The above-described conventional gumming devices have a considerable drawback, i.e., the adhesive substance insufficiently penetrates, in many cases, in said indents, and due to the high rotation rate of the gumming roller, tends to escape relatively easily from said indents and to settle on the surface of the roller outside the indents, with the consequence that the subsequent contact of the gumming roller with the surface to be gummed of each stamp causes application of the adhesive substance outside the desired areas or points.

is A solution to the above drawback is to use a gumming device, for example of the type described in British patent no 1,172,914, in which the gumming roller is externally limited by a cylindrical surface, on which hollows having the shape of a truncated pyramid are distributed.

The particular configuration of said hollows allows greater penetration of the adhesive substance inside them, but has several drawbacks, the main ones being the relatively high manufacturing costs, and the fact that said truncated-pyramid hollows cannot be produced in any other way except by radial penetration of a point through the gumming surface. In the case of steel gumming rollers, the pressures required for the penetration of said point are normally such as to entail a surface deformation of the gumming surface that makes the roller unusable.

Furthermore, the quadrilateral shape of the larger end 3 face of said truncated-pyramid hollows entails the formation, on any adhesive substance that is accommodated inside each one of said hollows, of a passage in which, when said adhesive substance is subjected to centrifugal force due to the rotation of the gumming roller, concentrations of forces are produced that easily entail the breakage of said passage and the consequent separation, by centrifugal force, of drops of adhesive substance, which cause smearing on the surface of the stamps.

It would be desirable to be able to provide a gumming device that is free from the above-mentioned drawbacks.

According to the present invention, a gumming device is provided which comprises: a container, which is formed in a downward region by a tank for an adhesive substance; a gumming roller, which is rotatably supported by said container and is at least partially limited externally by a gumming surface that has a plurality of hollows; and a scraper, which is adapted to skim over said gumming surface; said gumming roller having an upper portion that lies outside said container and a lower portion that is arranged inside the container in such a position as to receive the adhesive substance from said tank; characterized in that each one of said hollows is frustum- shaped and the larger end face is arranged on said gumming surface.

The present invention is now described with reference to the accompanying drawings, which illustrate a non- 4 limitative example thereof, wherein: figure 1 is a schematic sectional view of a preferred embodiment of the gumming device according to the present invention; 5 figure 2 is an enlarged-scale partial fold-out plan view of a detail of figure 1; and figures 3 and 4 are enlarged detail views showing the hollows of the gumming roller respectively in cross section and in a top view.

With reference to figure 1,. the reference numeral I generally designates a gumming device for applying an adhesive substance 2 to material in sheet form, constituted in particular by state stamps 3, which are caused to advance in succession, with a surface 4 directed downward, along a path 5 that is def ined by the peripheral region 6 of a suction transport roller 7 that can rotate, counterclockwise in figure 1, about an axis 8 that lies transversely to an advancement direction of said stamps 3 along the path 5. 20 The gumming device 1 comprises a container 10 that is substantially shaped like a cup-shaped right-angled parallelepiped and in turn comprises: a front wall 11 and a rear wall 12, both of which are vertical and mutually parallel; two end walls 13, only one of which is shown in figure 1, which are arranged parallel to each other and at right angles to the walls 11 and 12; and a bottom tank 14, which is adapted to contain the adhesive substance 2. As illustrated in figure 1, inside the container 10 there is a gumming roller 15 that can rotate, clockwise in figure 1, about an axis 16 that lies parallel to the axis 8 of the roller 7 and on the opposite side with respect to said roller 7 relative to the path 5.

The gumming roller 15 is externally limited by a cylindrical gumming surface 17, an upper portion 18 of which is arranged tangent, at a gumming station 19, to the path 5 of the stamps 3 and protrudes from a slot 20 that is formed through a lid 21 which is fixed to the upper end of the walls 11, 12, and 13 so as to close said container 10; a lower portion 22 of said surf ace is arranged so as to be immersed in the tank 14.

Still with reference to figure 1, a scraper 23 is arranged inside the container 10 and comprises an end 24 that is connected to the wall 11, whereas the opposite end is constituted by a U-shaped blade 25, an edge of which is arranged substantially in contact with a generatrix of the surface 17 of the gumming roller 15.

As illustrated in figures 2, 3 and 4 a plurality of frustum-shaped hollows 27 are distributed on the surface 17; they are divided into groups 28 that are uniformly distributed on said surface 17, are moved by the roller 15 through the station 19 in step with the stamps 3, and have a length that is substantially equal to that of said stamps 3.

In the illustrated example, each group 28 is formed by two pairs 29 of rows 30 of hollows 27, which are adapted to distribute the adhesive substance 2 along the opposite lateral edges of each stamp 3.

Since the hollows 27 are frustum-shaped, they are easy and cheap to produce by chip-forming machining, and 6 are also capable of effectively retaining the substance 2, since the passage that forms at their larger end face has a circular shape that is capable of ensuring a substantially uniform distribution of forces.

During use, as a consequence of the rotation of the roller 15, an amount of adhesive substance 2 adheres to the surface 17 of said roller 15, penetrating in the hollows 27, and is then raised towards the blade 25, the edge 26 of which removes the adhesive substance 2 that is present on said surface 17 outside the hollows 27.

Accordingly, after contact with the blade 25, the surface 17 is substantially clean; therefore, only the substance 2 that has penetrated in the hollows 27 is applied, at the station 19, to the surfaces 4 of the stamps 3, each one of which is fed by the roller 7 to said station 19, so that the corresponding surface 4 is, as mentioned, perfectly in step with a corresponding group 28.

The present invention is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept.

All the details may furthermore be replaced with other technically equivalent elements.

The materials employed, as well as the dimensions, may be any according to the requirements.

2 3 4 rotatably supported by said container 5 partially limited externally by a gumming surface 6 7 has a plurality of hollows; and a scraper is adapted to skim over said gumming surf ace gumming roller having an upper portion outside said container and a lower portion is arranged inside the container to receive the adhesive substance 8 9 11 7

Claims

1 1. Gumming device 1 comprising: a container which is formed in a downward region by a tank for an adhesive substance; a gumming roller which is and is at least that which said that lies that in such a position as from said tank 12 characterized in that each one of said hollows is 13 frustum-shaped and the larger end face is arranged on said 14 gumming surface 1

2. Device according to claim 1, characterized in that 2 said gumming surface is a cylindrical surface.

1

3. Device according to claim 1 or 2, characterized in 2 that said hollows on the gumming surface are 3 divided into groups that are uniformly distributed on 4 said gumming surface 1

4. Device according to claim 3, characterized in that 2 each one of said groups comprises a plurality of rows 3 of hollows 1 2

5. Gumming device substantially as herein described with reference to and as illustrated by the accompanying drawings.