GB2273287A

GB2273287A - Apparatus for forming bags

Info

Publication number: GB2273287A
Application number: GB9225579A
Authority: GB
Inventors: John Frederick Wilson
Original assignee: SMURFIT PACKAGING PRODUCTS
Current assignee: SMURFIT PACKAGING PRODUCTS
Priority date: 1992-12-08
Filing date: 1992-12-08
Publication date: 1994-06-15
Anticipated expiration: 2012-12-08
Also published as: GB9225579D0; GB2273287B

Abstract

Apparatus for forming bags from a continuous web of material 40 comprising a severing station 44 operable to sever unit lengths of material from the web and a feeding station 46 operable to feed the unit lengths to a bag forming station 48, the feeding station 46 comprising first and second drive rollers, wherein cut-out forming means associated with the drive rollers are operable to form at least one cut-out in each unit length to constitute a bag handle. <IMAGE>

Description

APPARATUS FOR FORMING BAGS This invention relates to apparatus for forming bags from a continuous web of material and in particular but not exclusively to apparatus for forming paper bags.

It is known to provide such apparatus for making paper bags which comprises a series of rollers which grip and translate unit lengths severed from a continuous web of paper to a bag making station.

Paper taped handles which are attached to the external surface of the bag, have been attached to the bags off-line in a separate process.

It is more convenient during manufacture if the bag is formed with a cut-out shape which in the finished article constitutes a handle. In addition, a cut-out handle allows the face of the bag to be fully printed.

Bags with cut-out handles have been produced using a web-feed mechanism which holds the web stationary during a vertical cutting operation so that the web moves in step-by-step fashion. This system considerably reduces the speed and efficiency of bag production.

There has therefore been a desire to have a bag forming apparatus which forms cut-out handles without loss of continuous movement.

Accordingly the present apparatus provides an apparatus for forming bags from a continuous web of material comprising a severing station operable to sever unit lengths of material from the web and a feeding station being operable to feed the unit lengths to a bag forming station, the feeding station comprising first and second rollers rotatable by drive means and co-operable to grip and translate each unit length wherein the feeding station comprises cut-out forming means associated with the rollers and operable to form at least one cut-out in each unit length to thereby constitute a handle in the bag so formed.

Preferably, the feeding station comprises at least one circumferentially extending resilient pad carried by one of the rollers and extending radially into contact with the other of the rollers whereby each unit length of material is accommodated between the respective rollers by compression of the pad.

There may be first and second circumferentially extending resilient pads which are axially spaced and wherein the cut-out means is operable at a location intermediate the pads.

Preferably the pads are carried by the first roller and are engageable with respective incompressible surface portions of the second roller.

The cut-out forming means is preferably a die carried by the first roller defining a cutting edge which is co-operable with a cylindrical surface portion of the second roller. The die is preferably removably mounted on the first roller. The cylindrical surface portion of the second roller may be a hardened steel sleeve.

There may be, located upstream of the feeding station, a printing station, wherein the drive means is operable synchronously with the printing station to locate the cut-outs in registration with marking applied to the web at the printing station. In addition, there may be, located upstream of the feeding station, tube forming means operable to form the web into a flattened tube.

Preferably there is a supporting structure supporting the first and second rollers such that they define rotational axes which are maintained in a parallel spaced relationship and comprising means for adjusting the spacing between the rotational axes.

A method for forming bags from a continuous web using the apparatus described above is also provided.

Preferred embodiments of the present invention will now be described in detail by way of example only with reference to the accompanying drawings, of which: Fig. 1 is a cross-section of the feeding station taken in a plane co-incident with the axes of the rollers of the apparatus.

Fig. 2 is a cross-section through the rollers along line II-II as shown in Fig. 1.

Fig. 3 is a schematic diagram of the production of bags with cut-outs for handles from a continuous web of bag forming material.

Referring to Fig. 1 there is shown a horizontal cylindrical first roller (2) located above and parallel to a cylindrical second roller (4). Both first and second rollers (2, 4) are rotatable about their horizontal axes by a geared drive mechanism (not shown). Mounted on the first rol-ler (2) by means of two screws (10) is a die block (8) defining a cutting edge (9) for forming handle cut-outs in unit lengths of paper (32). The cutting edge (9) of the die block (8) is shown in contact with a unit length of paper (32) which is running horizontally across the surface of the second roller (4). Also mounted on the first roller (2) are two semicircular bosses (12) which project axially and radially from respective ends of the first roller (2). Mounted on the circumference of the semicircular bosses (12) are resilient polyurethane strips (16).The polyurethane strips (16) make contact with the horizontal unit lengths of paper (32).

The first roller (2) is mounted on a horizontal shaft (18). The first roller (2) is prevented from horizontal movement along the shaft (18) by two nuts (20) which are received on threaded end portions of the shaft (18).

The second roller (4) is mounted on a horizontal shaft (35) and comprises left and right annular steel surface portions (30, 23) separated by a hardened steel sleeve (24) which is located so as to make contact with the cutting edge (9) of the die (8). A left end (28) of the second roller (4) is detachable from the main body of the second roller (4) by two screws (26). When the left end (28) of the second roller ( 4) has been removed, the left annular steel portion (30) may be removed and the central surface portion (24) removed and replaced.

Positioning of the first roller (2) in relation to the second roller (4) is adjusted by vertical movement of the shaft (18) by the adjusting mechanism (22). The adjusting mechanism comprises a handle (41) which turns a worm gear. Movement of the worm gear results in rotation of a gear (25) which results in vertical movement of a vertical shaft (27) and of bearing assemblies (29) which house the ends of the horizontal shaft (18) on which is mounted first roller (2). One full rotation of the handle (41) moves the first roller (2) 0.002 inch vertically.

Referring to Fig. 2 there is shown the first roller (2) mounted on the central shaft (18).

Circumferentially mounted on the surface of the first roller (2) is the die block (8) and the semicircular bosses (12) having mounted radially thereon polyurethane strips (16). The horizontal unit length of paper (32) is shown in contact between the cutting edge (9) of the die block (8) and the central surface portion of hardened steel (24) of the second roller (4).

Referring to Fig. 3 there is shown schematically a single continuous web of paper (40) being fed into a bag making assembly line. The assembly line comprises, in sequential order, a printing, folding and edge glueing station (42), a severing station (44), a feeding station (46) which forms the cut-outs in the paper material and a bag forming station (48). After the severing station (44) the bag making material is in unit length pieces (32). The bag forming station (48) which is last in the assembly line folds and glues the bottom portion of the individual length of paper forming complete bags.

In use as apparatus for forming bags the die block (8) is firmly attached to the circumference of the first roller (2) by two screws (10). Positioning of the first roller (2) in relation to the second roller (4) is critical to ensure that the die block (8) cuts through the unit length of paper (32) but does not exert unnecessary pressure on the second roller (4) which may lead to bouncing of the cutting edge (9) of the die block (8) on the second roller (4) and result in uneven rotation of the first (2) and second (4) rollers. Adjustment of positioning of the first and second rollers (2,4) is carried out by the adjusting mechanism (22) before use of the apparatus.

In the bag making assembly line a continuous web of paper (40) is fed to the printing, folding and edge glueing station (42). Here the surface of the paper is printed, the continuous single sheet web (40) is folded into a web of double thickness and the edges of the folded web are glued to form a continuous web in the form of a flattened tube. The severing station (44) cuts the continuous web (40) into individual lengths of paper (32). This severing station (44) feeds the individual lengths of paper into the feeding station (46). Because the individual pieces are in the form of flattened tubes only a single cut from the die block (8) is required to form the cut-out handle in both sides of the paper to be formed into bags.

The individual length of paper (32) is gripped between the second roller (4) and the polyurethane strips (16) radially extending from the first roller (2). Rotation of the first (2) and second (4) rollers feeds the individual length to the bag forming station (48) in the assembly line. For each rotation of the top roller (2) the die block (8) comes into contact with the individual length of paper (32) once and cuts one handle shape.

At the feeding station (46) it is important that the polyurethane strips (16) are of suitable hardness to result in smooth rotation of the first (2) and second (4) rollers. If the polyurethane is too hard it may result in bouncing of the first roller (2) on the second roller (4) when the cutting operation is carried out.

The steel sleeve (24) of second roller (4) on which the die (8) cuts is preferably of hardened steel, since the steel conventionally used for this second roller may become eroded by the continual force of the cutting die. Instead of hardened steel, ceramic material may be used (although at greater expense).

Claims

CLAIMS:

1. Apparatus for forming bags from a continuous web of material comprising a severing station operable to sever unit lengths of material from the web and a feeding station being operable to feed the unit lengths to a bag forming station, the feeding station comprising first and second rollers rotatable by drive means and co-operable to grip and translate each unit length wherein the feeding station comprises cut-out forming means associated with the rollers and operable to form at least one cut-out in each unit length to thereby constitute a handle in the bag so formed.

2. Apparatus as claimed in claim 1 wherein the feeding station comprises at least one circumferentially extending resilient pad carried by one of the rollers and extending radially into contact with the other of the rollers whereby each unit length is accommodated between the respective rollers by compression of the pad.

3. Apparatus as claimed in claim 2 comprising first and second pads which are axially spaced and wherein the cut-out means is operable at a location intermediate the pads.

4. Apparatus as claimed in claim 3 wherein the pads are carried by the first roller and are engageable with respective incompressible surface portions of the second roller.

5. Apparatus as claimed in any preceding claim wherein the cut-out forming means comprises a die carried by the first roller and defining a cutting edge which is co-operable with a cylindrical surface portion of the second roller.

6. Apparatus as claimed in claim 5 wherein the die is removably mounted on the first roller.

7. Apparatus as claimed in any of claims 5 and 6 wherein the cylindrical surface portion comprises a hardened steel sleeve.

8. Apparatus as claimed in any preceding claim comprising a printing station located upstream of the feeding station and wherein the drive means is operable synchronously with the printing station to locate the cut-outs in registration with markings applied to the web in the printing station.

9. Apparatus as claimed in any preceding claim comprising tube forming means located upstream of the feeding station and operable to form the web into a flattened tube.

10. Apparatus as claimed in any preceding claim comprising a supporting structure supporting the first and second rollers such that they define rotational axes which are maintained in a parallel spaced relationship and comprising means for adjusting the spacing between the rotational axes.

11. Method for forming bags from a continuous web of material comprising feeding the continuous web to a severing station operable to feed the unit lengths to a feeding station being operable to feed the unit lengths to a bag forming station, the feeding station comprising first and second rollers rotatable by drive means and co-operable to grip and translate each unit length wherein the feeding station comprises cut-out forming means associated with the rollers and operable to form at least one cut-out in each unit length to thereby constitute a handle in the bag so formed.

12. Apparatus for forming bags substantially as hereinbefore described with reference to the accompanying figures.