GB2327405A

GB2327405A - Handrail of thermoplastic material

Info

Publication number: GB2327405A
Application number: GB9815518A
Authority: GB
Inventors: Paul Stray; John Neave; Adrian Edmund Barwood
Original assignee: SILVERTOWN UK Ltd
Current assignee: SILVERTOWN UK Ltd
Priority date: 1997-07-18
Filing date: 1998-07-17
Publication date: 1999-01-27
Also published as: GB9815518D0; DE19832158A1

Abstract

A handrail (10) for an escalator or moving walkway comprises thermoplastic elastomer, preferably at least of hardness Shore A 80 and is preferably C-shaped (11). The inwardly facing surface of the handrail may be presented by an insert (12) of different material and preferably a lower hardness than the rest of the handrail (10) which is preferably extruded. Ribs or grooves (18) may be provided on the inwardly facing or drive-contacting surface of the handrail to vary the surface area of contact with the drive means (14,15). The handrail may comprise longitudinal reinforcement cables embedded by an extrusion procedure in a relatively soft thermoplastic elastomer to provide a central core, the core being coated with a harder thermoplastic elastomer by a second extrusion procedure. The handrail may comprise two co-extruded parts of which one part is a thermoplastic elastomer. The use of the hard thermoplastic material to form the outer section of the handrail increases shape retention during extensive use and lowers the requirement for further reinforcement. The friction between the guide on which the handrail travels and the handrail (10) is also reduced.

Description

2327405 1 HANDRAIL OF THERMOPLASTIC MATERIAL This invention relates to a

flexible handrail suitable for use with an escalator or moving walkway, and to the manufacture of a handrail.

Present manufacturing procedures involve stepwise cure of vulcanisable material. This is slow, renders it difficult to achieve dimensional accuracy, and is dependent on mould surface quality in order to provide the quality of surface finish now commonly desired by customers.

In an attempt to provide an improved appearance, it has been proposed to manufacture the outer cover of a handrail from a rubber based polymer applied over a carcass of fabric material. The main tensile member of the handrail is steel wire. The inner surface of the handrail typically is defined by a rubbing layer coated with rubber on one side in a manner arranged such that the rubber does not bleed through the rubbing layer material. The coefficient of friction of the rubbing layer must not be too low, otherwise it is difficult to ensure correct force transmission from drive rollers, and the coefficient of friction must not be too high otherwise there is a tendency for the handrail to move in an irregular. stuttering manner.

It is additionally desired to improve the lip stiffness at the edge regions of the handrail (typically of C-shape cross-section), and longitudinal stiffness. Stiffness and shape retention of inwardly facing lips of the C-section is desired to improve safety of passengers. Greater control of how a belt changes shape with extensive use can also reduce wear on the belt, thus reducing the frequency of belt replacement. The simple expedient of adding fabrics to the handrail to improve lip and longitudinal 4 2 stiffness can present difficulties, particularly an enhanced risk of delamination.

Furthermore, a disadvantage of the use of some materials such as Hypalon is that they produce acids when cured. These create gases that attack the chrome finish of the manufacturing moulds. Although the moulds can be recut, in due course they need to be replaced, which is costly.

After making the invention, we have had the British Patent Office conduct searches on the priority applications and these searches located the documents which follow, and the searches reinforce the inventiveness of the present invention.

US 4 776 446 shows an extruded, C-shaped, reinforced handrail of polyurethane of 40 to 50 Shore A having two U-shaped wear strips of harder polyurethane of 40 to 75 Shore D. The wear strips have transverse slots and line the inside portion of the lip regions of the handrail.

GB 2 204 484A shows a reinforced C-shaped handrail which is injection-moulded from polyurethane of 90 to 95' Shore A and has two lamellated side parts with a waved outer surface and an indented outer surface.

GB 1 260 299 shows a continually extruded thermoplastic handrail of 25 Cshaped cross-section having slotted lips which insert into slots of an outer rubber cover.

US 5 367 407 shows a thermoplastic cover with a blend of vulcanisable rubber and thermoplastic, such a composite being used in conveyor belts.

3 US 5 133 443 shows a self-adjustable escalator handrail drive with balanced drive chain tension and comprising a housing and two driving rollers eccentrically mounted on two shafts. The roller engages oppositely-facing surfaces of the handrail.

US 5 133 443 shows a self-tightening multiple nip mangle-type handrail drive having eccentrically mounted rollers engaging opposite faces of the C-shaped handrail as it passes through the drive mechanism.

According to one aspect of the present invention we provide at least those portions of-a flexible handrail which are contacted by drive means, such as drive rollers, manufactured from a thermoplastic elastomer, such as Hytrel (instead of a rubber based polymer).

By the present invention it is further taught that the whole of, or substantially the whole of the handrail may be constructed from a thermoplastic elastomer instead of a rubber based polymer. The thermoplastic elastomer may have a hardness of at least Shore A 80. The elastomer may have a hardness of at least Shore A 90. The elastomer may have a hardness of Shore A 85 5'. It is further taught to use a hardness of between 40 and 55 Shore D. The handrail may be devoid of a reinforcing embedding fabric, or devoid of any embedded fabric. A particularly suitable thermoplastic elastomer is Hytrel, ex-Du Pont.

The handrail may contain an embedded, substantially inextensible longitudinal reinforcement. That reinforcement may be embedded in that thermoplastic elastomer which is for contact by drive means. The reinforcement means may be tape or wires. The wires or tape may be made of metal, for example steel.

4 The invention teaches also that the flexible handrail may be manufactured by a method comprising the use of injection moulding machines, or by using plastics extruders, or by using both. We prefer to extrude the handrail.

The manufacturing technique of a handrail according to one aspect of the invention may include extrusion of the handrail by a thermoplastic extruder. The handrail may be produced much more rapidly by an extrusion technique resulting in substantial cost savings. For example the handrail may be extruded at around 2m/min using this method of manufacture, compared with perhaps 6m per hour for a fabric-containing rubber based handrail.

The invention may comprise extruding a handrail having a harder material outer structure which defines lips and a softer material drive surface structure which engages in the drive means. Preferably the outer structure and drive surface structure are co-extruded.

The manufacturing technique may comprise the provision of longitudinal reinforcement, such as wire cords or cables embedded in a material by an extrusion procedure to provide a central core of the handrail, disposed close to or at the inward facing surface of the handrail. The embedded material may be thermoplastic, and may be of relatively low hardness.

That preformed reinforcement structure may then be fed through a crosshead extruder to be coated with a harder grade of thermoplastic elastomer, which has a lower co-efficient of friction so as to form the outer and lip regions of the handrail. Typically, the harder grade of thermoplastic elastomer has a hardness around or exceeding 90 Shore A.

The handrail preferably has a C-shaped cross-section. The handrail preferably has a hardness of at least 80 Shore A. It may be sized through a die system but preferably this is not necessary. The handrail may have 5 longitudinal reinforcement provided, such as cables, tape or steel wire. Reinforcement may be provided during the extrusion process itself, or it may be added to the extruded handrail. Specifically, if tape is used as longitudinal reinforcement, the handrail and tape may be coextruded.

A core of material of lower hardness may be provided, and the core may be of thermoplastic material. The longitudinal reinforcement may be coated with the softer material during a separate extrusion process to form the softer core (or they may be co-extruded). The extruded handrail of harder thermoplastic material and the extruded core of less hard material can be brought together as a co-extrusion, or as two separate extrusions which are heat welded together, or attached in any other convenient way. If the two materials are thermoplastics, they need not necessarily be the same material (but they could be the same material). The core is disposed close to or at the inward facing surface of the completd handrail. The handrail therefore has a relatively soft inner core and harder outer and lip regions. Typically the harder grade material has a hardness around or exceeding a 90 Shore A. The softer grade thermoplastic material which forms the core region has a higher coefficient friction than the harder grade material, and therefore contacts the drive means efficiently.

The resulting handrail may not need a fabric reinforcement owing to the use of the harder grade thermoplastic in the outer and lip portions of the handrail.

6 Once the handrail is extruded and cooled, it may not need another surface finish. The extruded handrail may already have a smooth enough outer surface to use without further manufacturing steps.

A further advantage of the extruded handrail is the ease and speed with which the colour of the extruded material can be changed. Extrusion of handrails allows a rapid colour change to an alternatively -coloured handrail with only a small amount of waste extrusion. This waste will be an intermediate colour between the original colour and the new colour.

The free ends of a handrail (e.g. an extruded handrail) can then be joined, preferably by an injection moulding step.

In one aspect the present invention may therefore provide a flexible handrail formed from two types of thermoplastic elastomer. It further provides that the core region of the handrail comprises a thermoplastic elastomer of a relatively soft characteristic, but typically greater than Shore A 70 (or greater than Shore D 30), and which is of a hardness less than that of the surrounding layer which forms the 'outwardly facing visible surface of the handrail. The core part of the lower hardness may contain an embedded longitudinal reinforcement. The reinforcement may be one of, or any combination of cables, tape, or wires. The cables, wires or tape may be of steel. The handrail may be devoid of reinforcing fabric layers. The relatively soft elastomer may have a hardness of up to 70, 80 or 85 Shore A, and the harder elastomer may have a hardness of at least 80, 85 or 90 Shore A. The harder elastomer may have a hardness of at least 5, or more degrees Shore A harder than the softer elastomer.

Not all of the inwardly facing surface of the handrail need be formed by the softer grade of thermoplastic elastomer. In that case the softer grade 7 material is positioned for contact by drive rollers, but does not normally present frictional resistance to sliding movement of the handrail over standard guide devices (e.g. the softer grade material may not extend to the oppositely-directed lip portions of the C-cross section which have a sliding contact with guide formations of a handrail system of an escalator).

It is difficult to colour the prior art handrails constructed of thermoset rubbers such as traditional rubbers or neoprenes. When colouring has been completed, the colours age readily. One advantage of the present invention is the ease with which the thermoplastic elastomers permit colouring of the handrails andlor the greater ability of thermoplastic materials to resist colour changes with age. The handrails may have a colouring pigment. The handrails are preferably black but may be red, blue, green, yellow, orange or another colour. The colours may be bright colours. The handrail according to the present invention will retain these colours with use better than the prior art handrails.

The handrail may have no softer core region. Alternatively a softer core region may be provided. In either case, the inwardly facing side of the handrail, or a portion of the inwardly facing side of the handrail may be provided with means to alter the surface area of the inwardly facing side of the handrail to vary friction between the drive means and the surface of the inwardly facing side of the handrail, to obtain optimum drive means characteristics.

The surface area modifying means may be in the form of longitudinal grooves which extend in a direction substantially parallel to the longitudinal axis of the handrail and along part of, or the whole of, the inwardly facing surface of the handrail.

8 The surface area modifying means may be in the form of longitudinal ribs or protrusions which extend axially along part of, or the whole of, the inwardly facing surface of the handrail.

Alternatively a second series of surface area modifying means may be provided across part of, or the whole of the inwardly facing surface of the handrail in a transverse direction, substantially perpendicular to the longitudinal axis of the handrail. The second set of surface area modifying means may be any one of, or a combination of transverse ribs, transverse grooves or transverse protrusions.

In a further alternative, both the longitudinal surface area modifying means and the transverse surface area modifying means may be provided on the whole of, or on part of, the inwardly facing surface of the handrail.

We believe the handrail according to the invention will have an improved retention of lip profile compared to existing handrails. The reduced separation between lips results in improved safety for passengers because there is much less chance of fingers being pinched between the guide means and the handrail lip. Additionally, the handrail will require less maintenance work.

The invention further provides a handrail installation comprising handrail drive and guide means in combination with a handrail of the invention and arranged such that drive means operate on the softer material which is positioned so as not normally to present frictional resistance during movement of the handrail over guide means.

9 According to another aspect of the invention, we provide a handrail constructed from a thermoplastic elastomer (instead of a rubber based polymer).

Preferably, the handrail is extruded.

The drive means may be of a kind comprising a first member which bears against an inwardly facing surface of the handrail, and a second drive member which bears against the outwardly facing, visible surface.

The outwardly facing part contacted by the second drive member preferably is of a thermoplastic elastomer of a harder grade than that contacted by the first drive member.

Preferably guide means for the handrail is arranged to act on material of a harder grade than that of the first section of the handrail contacted by the first drive member.

Embodiments of the invention will now be described by way of example 20 only, with reference to the accompanying drawings in which:

Figure 1 shows a handrail according to the present invention adjacent a drive roller.

Figure 2 shows the handrail of Figure 1 passing over guide surfaces.

Figures 3 and 4 show transverse cross-sections of a handrail with longitudinal surface area modifying means; Figure 5 shows a transverse cross-section of a handrail with a second part and longitudinal surface area modifying means; Figure 6 shows a transverse cross-section of a handrail with transverse surface area modifying means; Figure 7 shows a cross-section of the handrail of Figure 6 viewed along the line 7-7; Figure 8 shows a transverse cross-section of a handrail - a second part of which is disposed close to the inwardly-facing surface of the handrail; Figure 9 shows a cross section of the handrail of Figure 8 with surface area modifying means; Figure 10 shows a perspective view of the handrail of Figure 8; and Figure 11 shows a perspective view of the handrail of Figure 2.

In Fig. 1 which is a cross-section of part of a handrail installation a handrail 10 comprises an outer C-shaped portion 11 of a thermoplastic elastomer such as Hytrel of Shore D hardness greater than the hardness, Shore A 90 of a second part 12 which is positioned to face inwardly. The lip regions 13 are defined by the harder grade thermoplastic elastomer and define channels where the parts 13a or 13 b, which are generally parallel in this example, with harder guide surf ace-engaging surfaces.

1 11 A first drive roller 14 (or drive belt) is arranged to bear against the softer grade thermoplastic elastomer 12 and a second drive roller 15 (or drive belt) bears against the outwardly facing surface 16 of the handrail.

Movement of the handrail is controlled by guide means 17 as shown in Fig. 2 which locate in the undercut regions of the lip edges 13.

The surface area modifying means 18 as shown in Figures 3 to 9 may be grooves 19, protrusions 20, or ribs 21. The grooves 19 of the handrail of Figure 3 extend axially along the longitudinal axis of the handrail 10.

The grooves may be provided on the whole of the inwardly facing surface of the handrail 10, or along a portion of inwardly facing surface. There may be reinforcing means (not shown) such as tape or wire present adjacent the surface area modifying means.

The protrusions 20 on the inwardly facing surface of the handrail 10 of Figure 4 extend in a similar manner to the grooves 18 of Figure 3 and also act as surface area modifying means.

In Figure 5, the protrusions 20 are provided by the second part 12 which can be a relatively soft material, such as a thermoplastic of a lower hardness than the thermoplastic of handrail 10, and may contain reinforcing members such as wire or tape (not shown). The surface area modifying means are provided only on part of the inwardly facing surface of the handrail of Figure 5.

The transverse ribs 21 on the inwardly facing surface of the handrail of Figure 6 may be provided instead of, or in addition to, the surface area modifying means of Figures 3 to 5. A better view of the transverse ribs 21 of the handrail 10 can be seen in Figure 7.

12 The second part 12 of the handrail of Figure 8 does not form a portion of the inwardly facing surface of the handrail, but is disposed close to the inwardly facing surface. The second part may comprise a different material from the material of which the handrail 10 is manufactured and provides reinforcing means. Additional reinforcing means may be provided in the second part such as tape or wires (not shown).

A similar second part 12 is shown in Figure 9 adjacent the surface area increasing means 18.

The smooth outer surface 16 of the handrail can be seen in Figures 10 and 11. The smooth outer surface may be as a result of extrusion of the handrail and may require no further treatment during manufacture of the handrail. No surface area modifying means are shown in Figures 10 and 11, but may be present if required.

In another embodiment the softer material insert 12 of Figure 1 does not include longitudinal reinforcing means. Insert 12 may omprise a coating over the central part of the handrail, on the inside surface (but preferably not on the lips 13 which define guide surfaces).

13

Claims

1. A handrail for use with an escalator or a moving walkway wherein at least those portions of the handrail for contact by drive means comprise a thermoplastic elastomer.

2. A handrail according to claim 1 wherein the whole, or substantially the whole handrail is constructed from thermoplastic elastomer and at least some of said thermoplastic elastomer has a hardness of at least 10 Shore A 80.

3. A handrail in accordance with claim 1, wherein said thermoplastic elastomer has a hardness of at least Shore A 80.

4. A handrail in accordance with claim 1 or 2, wherein said thermoplastic elastomer has a hardness of at least Shore A 90.

5. A handrail in accordance with claims 1 or 2, wherein said hardness is in the range Shore D 40 to Shore D 55.

6. A handrail in accordance with any preceding claim and which is devoid of embedded fabric reinforcement.

7. A handrail in accordance with any preceding claim and which is constructed from two types of thermoplastic elastomer.

8. A handrail in accordance with claim 7 comprising a core region of a thermoplastic elastomer which is relatively soft compared with the hardness of a thermoplastic elastomer which forms the outwardly facing 30 visible surface of the handrail.

14

9. A handrail in accordance with claim 8, wherein that part of an inwardly facing surface for contact by drive means comprises said relatively soft thermoplastic elastomer.

10. A handrail in accordance with claim 8 or claim 9, wherein that part of the inwardly facing surface which may present frictional resistance during movement of the handrail over guide devices comprises a thermoplastic elastomer which is harder than said relatively soft 10 elastomer.

11. A handrail in accordance with claim 10, comprising lip regions formed by said relatively harder thermoplastic elastomer.

12. A handrail in accordance with any one of claims 8 to 11, wherein said relatively soft thermoplastic elastomer has a hardness greater than Shore A 70.

13. A handrail in accordance with any one of claim 8 to 12 wherein 20 said core region contains an embedded longitudinal reinforcement.

14. A handrail in accordance with any one of claims 7 to 13 which is devoid of embedded fabric reinforcement.

15. A handrail according to any preceding claim wherein part of, or the whole of, an inwardly facing surface has surface area modifying means.

16. A handrail according to claim 15 wherein said surface area modifying means comprises any one of, or a combination of: 30 longitudinally extending grooves, ribs, or protrusions.

17. A handrail according to claim 15 or claim 16 which comprises any one of, or a combination of: ribs, or protrusions extending transversely across part of, or the whole of, the inwardly facing surface of the handrail.

18. A handrail according to any preceding claim wherein the thermoplastic elastomer of the handrail is dyed, or otherwise modified to change its colour.

19. A handrail substantially as herein described with reference to the accompanying drawings.

20. A method of manufacture of a handrail comprising extruding a thermoplastic to form a handrail of hardness of at least Shore A 80.

21. A method of manufacture of a handrail comprising a first extrusion procedure to embed longitudinal reinforcement cables in a relatively soft type thermoplastic elastomer to provide a central coee, and a second extrusion procedure in which said central core is coated with a harder grade of thermoplastic elastomer.

22. A method of manufacture of a handrail comprising co-extruding two parts of which at least one part is a thermoplastic elastomer.

23. A handrail installation comprising a handrail in accordance with any one claims 1 to 19 with handrail drive means and handrail guide means.

16 A handrail installation in accordance with claim 23, wherein the drive means comprises a first drive member arranged to bear against an inwardly facing surface of the handrail, and a second drive member which bears against an outwardly facing surface of the handrail.

24.

25. A handrail installation in accordance with claim 24, wherein the first drive member bears against a portion of the handrail formed from a first thermoplastic elastomer and the second drive member bears against a portion of the handrail formed from a second thermoplastic elastomer which is of a harder type than the first thermoplastic elastomer.

26. A handrail installation in accordance with any one of claims 23 to 25, wherein the guide means contacts material of a harder grade than that contacted by the first drive member.

27. A handrail installation in accordance with claim 26, wherein said harder grade material has a lower coefficient of friction than the material contacted by the first drive member.

28. A handrail comprising thermoplastic elastomer.

29. A handrail according to claim 28 which is an extruded handrail.

30. A handrail according to claim 28 or 29 which has a first and second part, one of which is thermoplastic elastomer and the first and second parts are co-extruded.

31. A handrail according to claim 28 or 29 wherein the elastomer has a hardness of Shore A 85 5', or Shore A 85 P.

17

32. A handrail according to any one of claims 28 to 31 which has a colouring pigment.

33. A handrail according to claim 32 which has a colour selected from 5 the group: red, yellow, green, blue, orange, purple.

34. A handrail installation in accordance with claim 23 and substantially as herein described.