WO2006040575A1

WO2006040575A1 - Heat transfer system

Info

Publication number: WO2006040575A1
Application number: PCT/GB2005/003967
Authority: WO
Inventors: Colin Stanley Murphy
Original assignee: Simon Corrugating Machinery Ltd
Priority date: 2004-10-16
Filing date: 2005-10-14
Publication date: 2006-04-20
Also published as: TW200616786A; GB0423068D0

Abstract

A heat transfer system in which a continuous web of material (14, 15, 18) is carried past a hot plate surface (13) with one face of the web in contact therewith, a series of load applying plates (19) imposing a load on the upper face of the web (14, 15, 18) to maintain contact between it and the hot plate surface, and conveyor means (16, 17) for transporting the web past the hot plate surface. A top conveyor belt (16) passes beneath the plates (19) in a %rst section of the system but is directed above the plates (19) in a subsequent section thus to prevent excessive wear of the belt (16) and to allow moisture to escape from the web (14, 15, 18) before it enters a final traction section between belts (16, 17). Thus, the web is positively carried through the heat transfer system with contact maintained between the web and the hot plate surface, while minimising wear of the conveying belt (16) and ensuring adequate escape of moisture from the web.

Description

HEAT TRANSFER SYSTEM

This invention concerns heat transfer systems wherein a continuous web of material is to be transported across the surface of one or more hot plates whereby the web is subjected to an elevated temperature for a predetermined period.

Particularly, though not exclusively, the invention is concerned with corrugating machinery in which a continuous web of single-faced fluted board with glue applied to the exposed tips of the fluted board is brought together with a liner which is thus bonded to the glued tips to form a double-faced board, and the composite board is carried over a bank of heaters or hot plates which assist in the bonding of the liner to the corrugated tips of the single-faced board.

A system of this kind usually incorporates means for imposing a load on the opposite face of the web from that which is in contact with the hot plates thus to maintain uniform contact between the board and the heated surface in order to ensure adequate heat transfer. Since, with such equipment there is a tendency for the hot plate surfaces to become distorted, the load applying means is so designed as to present a flexible surface so that the web is held with a substantially uniform pressure across its entire width against the hot plate surfaces as it travels through the system. Several different arrangements have been proposed for this purpose such as fluid filled vessels and spring loaded or pivotal shoes.

In order to transport the web over the hot plates a traction device is provided downstream of the hot plates in the direction of travel of the web and consisting of a pair of traction belts disposed respectively on opposite faces of the web. The upper of the traction belts traditionally carries the web over the hot plates and thus travels with the web over the hot surface, but this leads to wear of the top traction belt as it passes over the hot plates, particularly when the belt is wider than the web and thus in its edge regions is in sliding contact with the heated surfaces. Also, the presence of the belt over the web restricts the escape of moisture therefrom In order to overcome this problem it was proposed to remove the traction belt from that part of the system containing the hot plate surfaces, but this led to difficulties in threading the web into and through the system initially since traction was then applied only at the downstream end of the system to pull the web through.

Both of these known systems have disadvantages, hi the fully belted system, aside from belt wear, there is sometimes insufficient heat transfer since the load applying means is not in direct contact with the web as it passes over the hot plates, whereas in the belt-less system there is difficulty in threading up the machine and there is a tendency for the web to break where all of the traction is applied downstream of the heating section.

It is an object of the present invention to provide a heat transfer system which substantially overcomes these difficulties.

According to the present invention there is provided a heat transfer system in which a continuous web of material is carried past a hot plate surface with one face of the web in contact therewith, there being means imposing a load on the opposite face of the web to maintain said contact between the web and the hot plate surface, and conveyor means for transporting the web past the hot plate surface; characterised in that the load applying means comprises first and second sections aligned in the direction of conveyance of the web; in that in one of the sections a conveying belt is disposed between the load applying means and the hot plate surface; and in that in the other of the sections the load applying means is disposed to be in direct contact with the web as it travels past the hot plate surface.

Li said one of the sections the conveying belt may be disposed between the load applying means and the web as the latter travels past the hot plate surface. Said one of the sections may be the first section in which the web travels past the hot plate surface.

The conveying belt may pass through the other of said sections being diverted above the load applying means therein.

The coneyor means may include a traction section comprising a pair of traction belts disposed respectively on opposite faces of the web, each said belt being disposed in said traction section entirely beyond the hot plate surface in the direction of conveyance of the web .

One of said traction belts may be the conveying belt which in said one of the sections is disposed between the load applying means and the hot plate surface, said conveying belt being diverted above the load applying means in said other of the sections and continuing through the traction section.

The first and second sections of the load applying means may be of substantially equal length.

The length of the first section of the load applying means may be three quarters of that of the second section thereof.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a side elevation of a known machine for applying heat to a travelling web;

Fig. 2 is a similar view of another known machine for a similar purpose; and Fig. 3 is a similar view of a machine for a similar purpose and made in accordance with the invention.

Referring now to Fig. 1, a so-called doubled-facer for corrugated board comprises a heating section generally indicated at 10 and a traction section generally indicated at 11.

In the heating section a bed of hot plates 13 provides a heated surface over which a continuous web of single-faced fluted board 14 with glue applied to the exposed tips of the fluted board is brought together with a plain liner sheet 15 which is thus bonded to the glued tips to form a double-faced board, the composite board so formed being carried over the hot plates 13 which assist in the bonding of the liner sheet 15 to the corrugated tips of the board 14. An upper traction belt 16 driven from the traction section 11 carries the board through the heating section 10 and the traction section 11 with the assistance of a lower pulling belt 17 therein, to issue from the end of the double-facer at 18 in the form of a fully corrugated board.

In the heating section 10, above the belt 16, is a series of weighted skid plates 19 which are thus in sliding contact with the upper face of the belt 16 and apply a load, through the belt, to the transported board thus pressing same onto the hot plates for maximum heat transfer.

In the traction section 11 a bed of rollers 20 is located beneath the board and over which the belts 17 and 16, and the board, travel. Above the belt 16 in the traction section 11 is a series of fluid filled vessels which serve to maintain adequate drive contact between the belts 16 and 17 and the board.

Referring now to Fig. 2, in a modified machine the upper belt 16 is disposed only in the traction section 11 and does not pass between the skid plates 19 and the board. Thus, this is a so-called belt-less system and avoids belt wear while ensuring that the skid plates are in direct contact with the board to provide maximum contact between the board and the hot plates. As stated previously, this has the disadvantage, however, that it is difficult to thread up the machine initially since there is no conveying mechanism at the feed end of the machine and it is necessary to direct the board through to the traction section before conveyance may commence.

Referring now to Fig. 3, and in accordance with the invention, the belt 16 is applied to the feed end of the machine and as with Fig. 1 passes between the skid plates 19 and the board in a first part of the heating section 10. In this example, after the belt has passed beneath six of the skid plates 19 it is diverted via rollers 30 to pass above the remaining heating section as illustrated at 31 before returning to the traction section over rollers 32. In this section, moisture can escape from the board.

hi this example, eight skid plates 19 are in direct contact with the board as it passes over the hot plates 13 whilst the board is initially transported over six skid plates 19 by the belt 16. This arrangement overcomes the difficulty of threading up the machine initially whilst ensuring maximum heat transfer and minimal belt wear in the second part of the heating section.

The invention is not limited to the details described in relation to Fig. 3. For example, the proportional lengths of the belted and belt-less parts of the heating section 10 may be other than as described and illustrated in order to produce the optimum combination, in the heated section, of traction and direct contact between the skid plates and the board.

In an alternative arrangement, the continuous belt 16 may be replaced by a pair of belts, one being located in the traction section as illustrated in Fig. 2 while the other may be an independently driven belt located over the first or upstream part of the heating section.

In a further alternative arrangement, several short traction belts may be provided in the heating section interposed with parts thereof in which the load applying means is in direct contact with the board. For example, a short belt may be provided beneath the first few skid plates followed by an un-conveyed part followed again by another conveyed part, and so on. In these conveyed parts conveyance may, instead, be by way of rollers or other drive means.

Various advantages accrue from having part-conveyance and part-direct contact. These include an improved quality of board due to adequate heat transfer, improved moisture removal, longer belt life since the extent to which the belt is subjected to sliding contact with the hot plates and the skid plates is reduced, and increased running speeds when compared with conventional machines of this kind. Another advantage is that existing machines, whether fully belted or belt-less, can be readily converted to the combined form in accordance with the present invention.

In a further alternative arrangement, the skid plates 19 may be replaced by a series of spring-loaded shoes or rollers disposed in sliding or rolling contact with the upper face of the conveyor belt in the first section.

Claims

1. A heat transfer system in which a continuous web of material is carried past a hot plate surface with one face of the web in contact therewith, there being means imposing a load on the opposite face of the web to maintain said contact between the web and the hot plate surface, and conveyor means for transporting the web past the hot plate surface; characterised in that the load applying means comprises first and second sections aligned in the direction of conveyance of the web; in that in one of the sections the conveying belt is disposed between the load applying means and the hot plate surface; and in that in the other of the sections the load applying means is disposed to be in direct contact with the web as it travels past the hot plate surface.

2. A heat transfer system according to claim 1 wherein, in said one of the sections, the conveying belt is disposed between the load applying means and the web as it travels past the hot plate surface.

3. A heat transfer system according to claim 1 or claim 2 wherein said one of the sections is the first section in which the web travels past the hot plate surface.

4. A heat transfer system according to any preceding claim wherein the conveying belt passes through the other of said sections being diverted above the load applying means therein.

5. A heat transfer system according to any preceding claim wherein the conveyor means includes a traction section comprising a pair of traction belts disposed respectively on opposite faces of the web, each said belt being disposed in said traction section entirely beyond the hot plate surface in the direction of conveyance of the web.

6. A heat transfer system according to claim 5 wherein one of said traction belts is the conveying belt which in said one of the sections is disposed between the load applying means and the hot plate surface, said conveying belt being diverted above the load applying means in said other of the sections and continuing through the traction section.

7. A heat transfer system according to any preceding claim wherein the first and second sections of the load applying means are of substantially equal length.

8. A heat transfer system according to any one of claims 1 to 6 wherein the length of the first section of the load applying means is three-quarters of that of the second section thereof.

9. A heat transfer system according to any preceding claim wherein the load applying means comprises a series of weighted skid plates disposed in sliding contact with an upper face of the conveying belt in said one of the sections.

10. A heat transfer system according to any one of claims 1 to 8 wherein the load applying means is a series of spring-loaded shoes or rollers disposed in sliding or rolling contact with the upper face of the conveyor belt in said one of the sections.

11. A heat transfer system according to any preceding claim wherein the conveyor means comprises a first conveyor belt disposed in said one of the sections, and as separate second conveyor belt disposed in said other of the sections.

12. A heat transfer system according to any preceding claim including several short traction belts in said one of the sections interposed with parts thereof in which the load applying means is disposed in direct contact with the web.