GB2073850A

GB2073850A - Deflecting Roller for Sheet-like Web Material

Info

Publication number: GB2073850A
Application number: GB8110840A
Authority: GB
Original assignee: Schweizerische Industrie Gesellschaft
Current assignee: Schweizerische Industrie Gesellschaft
Priority date: 1980-04-11
Filing date: 1981-04-07
Publication date: 1981-10-21
Also published as: DE3111649A1; GB2073850B; CH643796A5

Abstract

The roller consists of a sleeve (10) having a wall-thickness to diameter ratio of at most 0.05. Each end of the sleeve lies against a bearing surface (32) of a flange (30) having an edge rib (33). The flanges (30) are supported by roller bearings (34) on spindles (71) of supporting arms (60, 70). The roller has a low mass moment of inertia and at the same time can be produced in a simple manner by the use of a synthetic material reinforced with glass-fibre. By these means, even the thinnest material currently used can be handled on existing packaging machines wherein the web of wrapping material is moved intermittently. <IMAGE>

Description

SPECIFICATION Deflecting Roller for Sheet-Like Web Material The present invention relates to a deflecting roller for sheet-like web material.

Stringent requirements as regards low mass moment of inertia, true running and absence of electrostatic charges are imposed upon deflecting rollers, particularly when used in packing machines. In the past, good results have been achieved with rollers made of wood. These could be used for all qualities of paper and have no electrostatic charge. A disadvantage was that the rollers could not be produced true to size and, for a diameter of 39 mm, for example, exhibited a mass moment of inertia J of 1 50 kg mm2/mm of length of roller. The high moment of inertia manifested itself during the conveying of foil packing material in high tensile loading of the material that could lead to tearing.

An improvement was achieved when the wooden roller was provided with equidistant grooves extending almost to the axis of the roller.

The mass moment of inertia J could be reduced to 62 kg mm2/mm of length of roller. However, when the packing material used was an aluminium foil, the grooves caused a ribbing effect and it was not possible to produce smooth packing means.

Although tests with rollers in the form of aluminium tubes resulted in advantages regarding dimensional accuracy, true running and favourable production costs, they also brought disadvantages. These consist in a high mass moment of inertia J of 198 kg mm2/mm of length of roller in the case of a diameter of 38mm and a wall-thickness of 2 mm, and 116.4 kg mm2/mm of length of roller for a wall thickness of 1 mm.

Because of the very low friction between a roller of this kind and, for example, aluminium foil packing material, particularly with intermittent feed, it was found that the rollers was caused to turn more rapidly when the packing material was being withdrawn, so that the rollers continued to turn for some time after cessation of the feed of the paper. The great relative movement between the aluminium foil and the aluminium roller leads to damage to the foil.

The object of the invention is, therefore, to provide a deflecting roller, the movement of which relative to the web of material is insignificant and which exhibits advantageous properties as regards friction and electrical charge potential, virtually irrespective of the quality of packing material that is handled.

According to the invention there is provided a deflecting roller for guiding sheet-like web material in a processing machine, which deflecting roller is embraced by the material over at least one-twentieth of its periphery and is caused to rotate by the longitudinal displacement of the material, wherein the bearing surface of the deflecting roller is the outer surface of a sleeve made of non-metallic rigid material, and in that the sleeve is provided at each of its ends with a flange holding rotary bearing means.

Embodiments of the invention will now be described with reference to the drawings, in which: Figure 1 is a crosssection through a deflective roller in accordance with the invention with cantilever supports and through a web of material for showing the contact angle, Figure 2 is an elevational view, partly in section, of the deflecting roller of Figure 1, and Figure 3 is an elevational view of a deflecting roller with a support at each end of its ends.

Figures 1 to 3 each show a deflecting roller in accordance with the invention and consisting of a sleeve 10 and a flange 20, 30 at each end. The sleeve 10 is made of a non-metallic rigid material, for example a thermosetting plastics substance such as phenol resin or epoxy resin which is reinforced by glass-fibre material. The glassfibre material may be embedded in the form of a fleece of cloth in the synthetic resin composition. The ratio of the wall thickness of the sleeve to its diameter should not exceed approximately 0.05, i.e. in the case of a diameter of 30 mm for such deflecting rollers as mentioned in the introduction hereto, the wall-thickness should not be more than 1.9 mm. Since, as is well-known, glass-fibre reinforced synthetic resin is generally very stable as regards mechanical strength, the wall thickness may be in the order of magnitude of 1 mm.The mass moment of inertia J of such a sleeve having a diameter of 38 mm and a wall thickness of 1 mm is 86 kg mm2/mm of length of roller so that it lies only slightly above the value found to be the ideal in the case of grooved wooden rollers, as mentioned in the introduction.

The flanges 20 and 30 will depend upon the structure of the bearing. As shown in Figure 2, a bearing is provided on an overhanging shaft 50, 51. The flange 20 is accordingly formed by a sleeve insert 21 having a peripheral support shoulder 22 and an edge rib 23. The roller bearing 24 is prevented from sliding off the end of the shaft 51 by means of a circlip 25 and is pressed into the flange 20. Since it comprises a support shoulder 22 and an edge rib 23, the sleeve insert 21 provides a reliable bearing surface for the interior of the sleeve 10 and at the same time constitutes a retaining means at the end. The sleeve 10 can be secured to the sleeve insert 21 by a press fit or by means of an adhesive.

The contact angle Z and therefore the friction between the surface 0 of the sleeve and the web material M is determined by the arrangements of the front and rear guide elements (not illustrated) for the web.

In individual cases, the angle Z can be selected, within a certain range, to suit the requirements as regards-friction. A first coefficient of friction is achieved only by the use of synthetic resin and glass-fibre reinforcement. For rollers for guiding material in a moist atmosphere, the surface is covered separately with a coating varnish or protective varnish. This however, results in the surface becoming smoother, and the coefficient of friction can diminish. To counter this, the sleeve can be provided with round grooves in a very simple way, so that the surface is slightly corrugated.

The arrangement shown in Figure 32 differs from that previously described only as regards the form of the flange 30. Here, the flange itself is provided with a bearing surface 31 for the sleeve 10 and with an edge rib 33. In this case, the roller bearing 34 is pressed by its outer ring and edge rib 31 into the flange 30 and by its outer ring directly on to the mounting spindle 71 of the supporting arm 70. The edge rib 31 is of advantage for securing the flange 30 in the lateral direction. The means comprising the supporting arm 60 on the right of the Figure does not differ from the fully illustrated means comprising the supporting arm 70.

Tests with deflecting rollers of this kind have shown that dimensional precision can be easily achieved and that, because of the low mass moment of inertia, virtually no further rotation of the roller could be detected after the web material had come to a standstill. Even a known wrapping material made of aluminium foil having a thickness of 0.009 mm, as normally used these days for the wrapping of chocolate, could be guided with ease; no cracks were observed when the rnatei-ial was pulled forward, nor was it possible to detect any adhesion to the rollers as a result of electrostatic charging which would indicate relative movement between the roller and wrapping material.

However, since in the described form of construction the sleeve constituting an electrical insulator, electrical charges could sometimes build up for other reasons. This can be remedied 'in a very simple way if a conducting material, e.g.

in the form of carbon particles, is mixed into the synthetic resin.

Claims

1. A deflecting roller for guiding sheet-like web material in a processing machine, which deflecting roller is embraced by the material over at least one-twentieth of its periphery and is caused to rotate by the longitudinal displacement of the material, wherein the bearing surface of the deflecting roller is the outer surface of a sleeve made of non-metallic rigid material, and in that the sleeve is provided at each of its ends with a flange holding rotary bearing means.

2. A deflecting roller according to claim 1 wherein the flanges are made of light metal and have an edge rib, the height of which, beyond a circumferential support shoulder, corresponds at least approximately to the thickness of the material of the sleeve, and in that the rotary bearing means are roller bearings, the outer rings of which are held in the flanges.

3. A deflecting roller according to claim 1 or claim 2, wherein the non-metallic rigid materials of the sleeve is a hardenable plastics material and a reinforcing material.

4. A deflecting roller according to claim 3, wherein the plastics material is a heat-hardenable synthetic resin.

5. A deflecting roller according to claim 3, wherein the plastics material is an epoxy resin.

6. A deflecting roller according to claim 3, wherein the reinforcing material is a glass-fibre material.

7. A deflecting roller according to claim 6, wherein the glass-fibre material is a glass-fibre cloch.

8. A deflecting roller according to any of the preceding claims wherein the ratio of the wall thickness of the sleeve to the diameter of the sleeve is 0.05 maximum.

9. A deflecting roller according to any of the preceding claims wherein the outer face of the sleeve is provided with round grooves.

10. A deflecting roller according to any of the preceding claims wherein electrically conducting particles are distributed throughout the sleeve.

1 A deflecting roller according to claim 10, wherein the electrically conducting particles consist of carbon.

12. A deflecting roller substantially as hereinbefore described with reference to the accompanying drawings.