GB2458996A

GB2458996A - Reinforced moulded hose

Info

Publication number: GB2458996A
Application number: GB0806704A
Authority: GB
Inventors: Diane Gibson
Original assignee: Smiths Group PLC
Current assignee: Smiths Group PLC
Priority date: 2008-04-12
Filing date: 2008-04-12
Publication date: 2009-10-14
Also published as: GB0806704D0

Abstract

A hose, a method of making the hose and an apparatus for making the hose are disclosed. A wire reinforcement element 10, with a varying pitch, is wound on to a mandrel 21 and a flexible wall material 11 is bonded to the element 10, such as by applying an extrusion 27 around the mandrel 21. Initially, a shaped timing belt 28 with a groove 30 is wrapped around the mandrel to rotate with it. The wire element 10 is fed through a wire form unit 24 with a pitch roller or other wire guide 25 set to give the wire the desired diameter and pitch.The wall material 11 and that of the coating on the wire element 10 may be of compatible plastics. Alternatively, the wall material 11 may be a fabric or a metal braid bonded to the wire element 10 by means of an adhesive etc.

Description

HOSES

This invention relates to hoses and their manufacture.

The invention is more particularly concerned with helically-reinforced hoses.

It is often an advantage for a hose to have a variable length. For example, vacuum cleaners are often provided with a stretch hose having a naturally-retracted length but which can be pulled to stretch to an extended length for cleaning at locations away from the cleaner. In this way, the hose can have a relatively short length for storage and a longer length during use. More recently a retractable hose has become available from Flexible Ducting Limited of Glasgow under the Vac-U-Store name (Registered Trade Mark) as described in EP14273 19. This hose has a naturally-extended length but can be retracted to a shorter length for storage by suction applied from the vacuum cleaner.

It is an object of the present invention to provide an alternative form of reinforced hose.

According to one aspect of the present invention there is provided a hose having a helical reinforcement element and a flexible wall attached with the reinforcement element, the pitch of the reinforcement element in a first region along the length of the hose being different from the pitch in a second region.

The hose may have at least four different regions along its length, the pitch of the reinforcement element being different in adjacent regions.

According to another aspect of the present invention there is provided a hose having at least two different regions along its length, one region having a naturally-extended state and an adjacent region having a naturally-compressed but extensible state.

According to a third aspect of the present invention there is provided a hose having alternating regions along its length of differing extensibility.

According to a fourth aspect of the present invention there is provided a method of making a hose including the steps of winding a wire reinforcement element onto a mandrel, varying the pitch of the reinforcement element along the mandrel, bonding a flexible wall material with the reinforcement element and subsequently removing the hose from the mandrel.

According to a fifth aspect of the present invention there is provided a hose made by a method according to the above fourth aspect of the invention.

According to a sixth aspect of the present invention there is provided a machine for making a hose including a rotatable mandrel, a wire guide for guiding a wire reinforcement helically around the mandrel, means for applying a flexible wall material around the mandrel to bond with the wire reinforcement and means for displacing the wire guide such as to vary the pitch as the reinforcement is guided onto the mandrel.

S

According to a seventh aspect of the present invention there is provided a hose made on a machine according to the above sixth aspect of the invention.

A hose and its method of manufacture will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a side elevation view of the hose; Figure 2 is a side elevation view of the hose to an enlarged scale and showing a part of a compressed region in section; Figure 3 is a side elevation view of the compressed region in a semi-extended state; and Figure 4 is a simplified side elevation view of the machine used to manufacture the hose.

With reference first to Figures 1 and 2, there is shown a hose 1 used to supply filtered air from a blower unit worn on a user's back to a mask or helmet (neither the blower nor mask being shown). The hose 1 is typically about 1000mm long with a diameter of about 32mm. It will be appreciated that the present invention is not confined to hoses for any particular application or to hoses of any particular dimensions or materials.

The hose 1 has seven different regions 2 to 8 along its length. Alternate regions 2, 4, 6 and 8 have different properties from respective adjacent regions 3, 5 and 7. More particularly, the even-numbered regions 2, 4, 6 and 8 have a naturally-extended state, that is, when no force is applied, these regions have an extended state that cannot be extended further to any substantial extent by applying an axial extensive force. In their natural state, the extended regions 2, 4, 6 and 8 have a typical length of about 150mm each. These regions 2, 4, 6 and 8 can, however, be retracted to a shorter length by applying an axial compressive force. In some applications, these regions might be arranged such that they could be retracted to a shorter length by applying a suction force within the hose, such as from a vacuum cleaner in the manner described in EP1427319. The intervening, odd-numbered regions 3, 5 and 7, by contrast, have a naturally-compressed state, that is, when no force is applied these regions have a contracted, compressed or short length that cannot be shortened further to any substantial extent by applying an axial compressive force. These region 3, 5 and 7 typically have a natural length of about 150mm but they can be extended to a longer length by applying an axial extensive force.

It will be appreciated that hoses can have any number of two or more such regions of different properties. It will also be appreciated that the regions could have any length and that regions having the same or different properties could have different lengths along the hose.

With reference now particularly to Figure 2, it can be seen that the hose I includes a helical reinforcement element in the form of a plastic-coated spring steel wire 10. The hose I also includes and a flexible sleeve or wall 11 of an impervious plastics material, such as

I

polyurethane, bonded to the outside surface of the wire 10. Preferably the material of the wall 11 and that of the coating on the wire 10 are of compatible plastics so that they can be bonded together by a solvent or by thermal bonding. The wall material could, however, be of a different material, such as a fabric or metal braid and could be bonded to the wire by using an adhesive or the like.

The wall 11 folds outwardly between the turns of the wire 10 as seen most clearly in the sectional view in the naturally-compressed region 3. The different properties of the naturally-extended and the naturally-compressed regions are achieved by the difference in pitch of the wire 10 in these regions. In the naturally-extended regions 2, 4, 6 and 8 the pitch of the wire 10 is relatively large whereas in the naturally-compressed regions 3, 5 and 7 the pitch is relatively small, with adjacent turns almost touching one another. The wall 11 is relatively flat between the turns of the wire 10 in the naturally-extended regions 2, 4, 6 and 8, with the peaks between turns of the wire lying below the external boundary of the wire. In the naturally-compressed regions 3, 5 and 7, however, the wall 11 projects outwardly in peaks beyond the wire 10. It is not essential that the wall 11 fold outwardly between turns of the wire 10, it could instead fold inwardly, but it is advantageous that it fold outwardly because, in this way, it does not restrict the bore through the hose.

The compressed regions 3, 5 and 7 have greater flexibility than the extended regions 2, 4, 6 and 8 and are also more crush recoverable; they are also, however, heavier per unit length of hose, and more expensive, than the extended regions because of the greater mass of wire. The present invention enables a unitary hose to be provided with the flexible, extensible and crush-recoverable properties located where they are most beneficial along the hose but without unduly increasing the overall weight and cost of the hose.

When an axial extensive force is applied between the two ends of the hose 1 it is able to accommodate this by stretching the naturally-compressed regions 3, 5 and 7. Figure 3 shows how the naturally-compressed region 3 starts to stretch, to a semi-extended state. If enough force were to be applied, the naturally-compressed regions 3, 5 and 7 would extend to a state where the pitch of the wire 10 in these regions was the same as those in the naturally-extended regions 2, 4,6 and 8. The ratio of the fully extended length to the natural compressed length could be between 1.5:1 and 4:1.

The hose could be made in various ways, such as by using a machine 20 of the kind shown in Figure 4. The machine 20 has a cylindrical, metal mandrel 21 rotated about its axis by a motor 22. A shaped timing belt 28 with a groove 30 is wrapped around the mandrel 21 to rotate with it. A drum 23 of the coated spring steel wire 10 is mounted alongside the mandrel 21 and the wire is fed through a wire form unit 24 with a pitch roller or other wire guide 25 set to give the wire the desired diameter and pitch, giving the wire the desired level of kick out or retraction to induce pull back. The groove 30 on the belt 28 holds the wire 10 in place while it is on the mandrel 21. In conventional hose-fonning machines the pitch roller is fixed in a set position during manufacture of a hose, to give the reinforcing element a constant pitch along the length of the hose. By contrast, in the present invention, the pitch roller 25 is movable substantially parallel to the axis of the mandrel 21 and is displaced while the hose 1 is being manufactured so as to alter the pitch of the wire 10 in the different regions 2 to 8. An extruder 26 mounted alongside the mandrel 21 delivers an extrusion 27 of a suitable material onto the timing belt 28 and wire 10 to form the hose wall 11. The wire 10 is previously wiped with a solvent 29 so that the extrusion 27 bonds to the outside of the wire. The overlapping turns of the extrusion itself are fused together by residual heat. The timing belt 28 allows the hose to drive off the mandrel as it is rotated and its groove 30 ensures that the hose wall overlaps and the construction remains fixed.

The machine enables a unitary hose to be manufactured with different regions of different extensibility along its length.

08.vlh

Claims

Claims 1. A hose having a helical reinforcement element and a flexible wall attached with the reinforcement element, the pitch of the reinforcement element in a first region along the length of the hose being different from the pitch in a second region.
2. A hose as claimed in claim 1, in which the hose has at least four different regions among its length, the pitch of the reinforcement element being different in adjacent regions.
3. A hose as claimed in any preceding claim, in which the hose has at least two different regions among its length, one region having a naturally-extended state and an adjacent region having a naturally-compressed but extensible state.
4. A hose as claimed in any preceding claim, in which the hose has altering regions among its length of differing extensibility.
5. A method of making a hose including the steps of winding a wire reinforcement element on to a mandrel, varying the pitch of the * reinforcement element along the mandrel, bonding a flexible wall :r material with the reinforcement element, and subsequently removing the hose from the mandrel. * 25 *.
6. A hose made by the method of claim 5. I...
7. A machine for making a hose, said machine including a rotatable mandrel, a wire guide for guiding a wire reinforcement helically around the mandrel, means for applying a flexible wall material around the mandrel to bond with the wire reinforcement, and means for displacing the wire guide such as to vary the pitch as the reinforcement is guided onto the mandrel.
8. A hose made on a machine according to claim 7.
9. A hose substantially as herein before described with reference to figures 1-3 of the accompanying drawings.

*
10. A method substantially as herein before described with reference to figures 1 to 4 of the accompanying drawings.
11. A machine for making a hose as herein before described with reference to figure 4 of the accompanying drawings. * * * I* * * * S... * I S... * *.. * ISS * S *.S.