Patent Description:
The multilayer tube according to the invention is suitable to be used for example in production lines with a high level of automation, particularly in the automotive industry, for the covering and protection of conduits and profiled elements made of plastic material in general, as well as cables or other similar longitudinally extended elements, with which robots and automated mechanical arms that are present in assembly lines are equipped.

In general, such a multilayer tube acts as a flexible protection element in order to protect said conduits and cables from damage and therefore from the risks of a consequent breakage.

These multilayer tubes must be suitable to withstand the frequent stresses that are imparted by the movements of the mechanical arm and the wear of the covering caused by continuous friction with metallic parts, keeping intact the cable/profiled element inserted inside it.

Currently, these multilayer tubes are generally constituted by.

In general, a robotic mechanical arm, in moving, traces trajectories with very tight radii of curvature; for this reason, a multilayer tube that is installed thereon must be capable of keeping its shape, minimizing its ovalization or in any case limiting it within a certain limit, such as to allow in any situation the sliding of the conduit or of the cable that passes inside it, at the same time preventing its structure from collapsing, damaging the conduit or the cable inside it.

Another important aspect of multilayer tubes for these applications is constituted by the fact that since the conduit or cable is fixed at least at the ends to the robotic arm of which it is a part, the multilayer tube that contains it must allow the conduit or cable to slide freely inside it in order to be able to follow the rapid and repeated movements of the robotic arm.

The movement of the robotic arm causes both the external friction of the multilayer tube with the metallic parts of the mechanical robot with which it is in contact and the internal friction between the conduit or cable arranged inside the multilayer tube and the internal surface of the tube itself.

These friction phenomena generate an accumulation of electrostatic charges, with considerable risk for the safety of the operator and of the apparatus due to possible discharges of electric current and the risk of triggering in the presence of potentially explosive environments.

<CIT> and <CIT> disclose a multi-layered containment and protection tube.

<CIT> discloses an electrically heatable multi-layer flexible pipe.

<CIT> and <CIT> disclose an electrically conducting multilayer hose.

The aim of the present invention is to provide a multilayer containment and protection tube for conduits, cables and the like that is capable of obviating the cited limitations of multilayer tubes of the known type.

Within this aim, an object of the invention is to provide a multilayer tube that prevents the accumulation of charges on the tube itself.

Another object of the present invention is to provide a multilayer tube that is capable of reducing the friction phenomena that are typical of multilayer tubes of the known type.

A further object of the present invention is to provide a multilayer tube that is no less mechanically strong, flexible and resistant than tubes of the known type.

This aim, as well as these and other objects which will become better apparent hereinafter, are achieved by a multilayer containment and protection tube for conduits, cables and the like according to claim <NUM>.

Further characteristics and advantages of the invention will become better apparent from the description of two preferred but not exclusive embodiments of the multilayer tube according to the invention, illustrated by way of nonlimiting example in the accompanying drawings, wherein:.

With reference to the figures, a multilayer tube according to the invention is designated, in the entirety of a first embodiment thereof, by the reference numeral <NUM>.

The multilayer tube <NUM> is characterized in that it comprises.

The inner layer <NUM>, according to the invention is made of PTFE.

PTFE in fact notoriously has the characteristic of an extremely low static and dynamic friction coefficient, therefore at the smooth internal surface <NUM> of the inner layer <NUM>, the value of which is approximately <NUM>; this value of the static and dynamic friction coefficient allows the internal surface <NUM> of the inner layer <NUM> to have a very low adhesion and to be self-lubricating.

This particularity facilitates the sliding of the conduit <NUM>, or of a cable or of another longitudinal element, inside the multilayer tube <NUM>, preserving the conduit or cable from abrasion and wear.

Furthermore, the low friction coefficient ensures a certain degree of self-cleaning, avoiding the forming of deposits within the multilayer tube <NUM>.

This particularity of exceptional lubricity that is typical of polytetrafluoroethylene also facilitates maintenance operations if the need arises to remove the conduit or cable or other profiled element from the inside of the multilayer tube <NUM>.

Maintenance in fact entails the extraction and subsequent re-insertion of the profiled element inside the tube; the exceptional lubricity of the internal surface <NUM> of the inner layer <NUM> made of PTFE allows to extract and reinsert effortlessly the conduit <NUM> or other cable or profiled element from the inside of the multilayer tube <NUM> without generating friction and preserving the conduit <NUM> or other cable or profile from abrasion.

This particular property of the inner layer <NUM> made of polytetrafluoroethylene also allows to reduce maintenance times considerably, since it is possible to replace and/or maintain the conduit <NUM> or other cable or profiled element, by extracting it and reinserting it in the tube without having to remove the multilayer tube <NUM> from its installation position on the mechanical arm.

The inner layer <NUM> made of PTFE fluoropolymer is also capable of ensuring exceptional resistance to flexing and vibrations, which are a very onerous aspect of the exemplified application to robotic arms.

In particular, the resistance to flexing and vibrations of PTFE is greater than that of all other commercially available fluoropolymers, and accordingly the inner layer <NUM> made of PTFE ensures a resistance to folding cycles (folding endurance ASTM D <NUM>) that is approximately two orders of magnitude greater than that of the other fluoropolymers (FEP, MFA, PFA, ECTFE, and PVDF).

Another inherent characteristic of the PTFE material is substantial non-flammability, which reduces the risk of triggering, increasing significantly the safety of the multilayer tube <NUM> according to the invention.

In particular, the inner layer <NUM> made of PTFE fluoropolymer is conducting and therefore acts as a medium for the discharge of the electrostatic charges that might accumulate during friction of the conduit <NUM> or cable or other profiled element in contact with the inner layer <NUM>.

Therefore, the useful life and the performance of the multilayer tube <NUM> with at least one inner layer <NUM> and made of PTFE fluoropolymer are greater than those of other tubes and the maximum ones currently commercially attainable.

It should be understood that the thickness of the inner layer <NUM> made of PTFE fluoropolymer can be of variable size according to the requirements of use (flexibility) or the choices of the manufacturer.

Advantageously, the inner layer <NUM> is a continuous tubular extruded element; by virtue of its provision by extrusion, an internal surface <NUM> is obtained without joining lines between parts, since the inner layer <NUM> is a single continuous part.

The inner layer <NUM> is preferably electrically conducting.

In this first embodiment, the one or more intermediate reinforcement layers <NUM> comprise at least one textile or metallic reinforcement layer <NUM>, for example a metallic braid.

In particular, the one or more intermediate reinforcement layers <NUM> comprise two textile or metallic reinforcement layers <NUM>, <NUM>.

A filler layer made of elastomeric material <NUM>, for example EPDM, which is at least antistatic and preferably conducting, is interposed between the two textile or metallic reinforcement layers <NUM>, <NUM>.

The outer layer <NUM> made of polymeric material is made of elastomeric material and is made for example of EPDM.

The outer layer <NUM> is electrically conducting.

The covering and finishing layer <NUM> is made of thermoplastic material.

According to the invention, said thermoplastic material of the covering and finishing layer <NUM> is ultra high molecular weight polyethylene UHMWPE.

The covering and finishing layer <NUM> made of thermoplastic UHMWPE is electrically conducting.

Also in particular, the covering and finishing layer <NUM> made of UHMWPE is completely black.

As an alternative, the covering and finishing layer <NUM> made of UHMWPE is constituted by a matrix with a white or whitish coloring which is provided with uniformly dispersed electrically conducting bridges.

As a further alternative, the covering and finishing layer <NUM> made of UHMWPE is marbled, with a carbon filler which gives it a substantially dark color.

Advantageously, the covering and finishing layer <NUM> has a substantially smooth and glossy external surface.

The substantially smooth and glossy external surface allows the multilayer tube <NUM> to have a distinct tendency to remain clean and also to be easy to clean, contrasting the adhesion thereon of the dust or dirt with which it can come into contact.

Furthermore, by virtue of the smooth outer surface of the covering layer <NUM>, the multilayer tube <NUM> slides easily, being easy to install and move.

As an alternative, it is possible to decide to use an outer covering and finishing layer <NUM> that is not glossy, bearing in mind however that in this case the tube will not have the specific advantages that derive from the smooth and glossy external surface finish.

A multilayer tube according to the invention also has an assurance of electrical dissipation of electrostatic charges by virtue of the conducting or antistatic covering.

The thermoplastic material of the covering and finishing layer <NUM> can be constituted by different materials, with different colorings, so long as they are electrically conducting or antistatic in order to allow dissipation of the electrostatic charges that can accumulate on the surface due to friction during use of the tube.

In a second embodiment, shown schematically in <FIG>, the multilayer tube according to the invention, designated therein by the reference numeral <NUM>, is characterized in that it comprises, in a manner similar to what has been described above for the first embodiment <NUM>,.

In this second embodiment, the one or more intermediate reinforcement layers <NUM> comprise a reinforcement spiral <NUM>.

The reinforcement spiral <NUM> is made of metallic material.

As an alternative, the reinforcement spiral <NUM> is made of thermoplastic material.

The reinforcement spiral <NUM> is wound in said tube with an inclination and a pitch that depend on the requirements of application and production.

In this exemplary embodiment, the spiral <NUM> is arranged between two layers of textile or metallic reinforcement <NUM> and <NUM>, together with an interposed filler layer made of elastomeric material <NUM>.

The arrangement and the number of spirals can vary and depend on the production technology and on the type of characteristics sought.

The choice to use a reinforcement spiral increases the performance of the multilayer tube <NUM>, since it allows the tube to maintain its shape without ovalizing beyond a certain limit, such as to allow the sliding of the conduit or cable or other profiled element arranged inside it.

In the specific example of application cited above, if the movements of a mechanical arm trace curvatures with a very tight radius, the metallic spiral <NUM> prevents the collapse of the tube, allowing the sliding of the conduit that is arranged inside it and avoiding its damage.

The choice of the material, the arrangement and the number of spirals depend on the manufacturer and of the type of performance that is required of the tube.

In practice it has been found that the invention achieves the intended aim and objects.

In fact, the invention provides a multilayer tube that prevents the accumulation of charges on said tube, by virtue of the inner, intermediate, outer and covering layers, all of which are at least antistatic, and in particular with the conducting inner and outer layers; said multilayer tube according to the invention acts as a means for discharging the electrostatic charges that might accumulate thereon.

Moreover, the invention provides a multilayer tube that is capable of reducing the friction phenomena that are typical of multilayer tubes of the known type, in particular by virtue of the inner layer with a smooth internal surface, by virtue of an inner layer made of PTFE, which has an extremely low static and dynamic friction coefficient.

Moreover, the invention provides a multilayer tube that is no less mechanically strong, flexible and resistant than tubes of the known type.

Claim 1:
A multilayer containment and protection tube (<NUM>, <NUM>) for conduits, cables and the like, the multilayer containment and protection tube (<NUM>, <NUM>) comprising:
- an inner layer (<NUM>, <NUM>) made of polymeric material with a smooth internal surface (<NUM>, <NUM>) which forms a duct for supporting conduits or cables, ,
- one or more intermediate layers (<NUM>, <NUM>) of reinforcement,
- an outer layer (<NUM>) made of a polymeric material,
- a covering and finishing layer (<NUM>, <NUM>),
said inner layer (<NUM>,<NUM>), said one or more intermediate layers (<NUM>,<NUM>), said outer layer (<NUM>) and said covering and finishing layer (<NUM>, <NUM>) being all electrically at least antistatic and
said inner layer (<NUM>, <NUM>) being made of polytetrafluoroethylene PTFE, characterized in that said material of said covering and finishing layer (<NUM>, <NUM>) is ultrahigh molecular weight polyethylene UHMWPE.