Heating sleeve and method for production and use

Abstract

The invention relates to a heating sleeve (1, 20, 23, 30, 33, 40) for electrical heating of a pipe (13), a container and / or a moulded part from the outside, having at least one electrically conductive heating section (21, 24, 31, 38, 41) in the form of a heating resistor for heating at least sections of the heating sleeve (1, 20, 23, 30, 33, 40). In order that electrical heating of pipes, containers and moulded parts can be carried out more cost effectively, more reliably and at the same time more efficiently, the heating sleeve (1, 20, 23, 30, 33, 40) is a shrink-fit sleeve with a diameter (D) that can be shrunk by heating, at least in sections, in order to be shrunk onto the pipe (13), container and / or moulded part, and the at least one heating section (21, 24, 31, 38, 41) has at least one thermoplastic (4) and at least one electrically conductive filler (5) finely distributed in a matrix of the at least one thermoplastic (4), and the at least one electrically conductive heating section (21, 24, 31, 38, 41) is designed to apply an electrical heating voltage or electrical heating current to shrink the diameter (D), at least in sections, as a result of heating the at least one heating section (21, 24, 31, 38, 41) and / or to inductively heat the at least one heating section (21, 24, 31, 38, 41) by way of an alternating magnetic field and to shrink the diameter (D), at least in sections, as a result of the inductive heating of the at least one heating section (21, 24, 31, 38, 41).

Description

[0001] Heating hose and method for manufacturing and using

[0002] The invention relates to a heating hose for electrically heating a pipeline, a container, and / or a molded part from the outside, comprising at least one electrically conductive heating section in the form of a heating resistor for heating the heating hose at least in sections. Furthermore, the invention relates to a method for producing such a heating hose and a method for shrinking such a heating hose.

[0003] Heating hoses of this type have been known in various designs for some time. They are used in particular as trace heating for heating pipelines, containers, molded parts, and the like. Due to their tubular shape, the heating hoses can accommodate the pipelines, containers, or molded parts at least in sections in order to heat them evenly from the outside over their circumference. For this purpose, one or more heating wires are provided in the heating hoses. These heating wires are electrically conductive and have such a high resistance that they form a heating resistor to which a heating voltage or heating current can be applied. As a result of the heating voltage or heating current applied to a heating hose, the heating wire heats up, which then transfers the resulting heat to the heating hose and the pipeline, container, and / or molded part inside the heating hose.

[0004] Trace heating systems are also known in the form of heating tapes, heating cables, and heating cords, which can be wound around pipes, containers, and fittings. These heating tapes, heating cables, and heating cords also have a heating wire, to the ends of which a heating voltage or heating current can be applied to heat the heating wire in the sense of resistance heating. The heating tapes, heating cables, and heating cords then transfer heat to the pipes, containers, and fittings around which the heating tapes, heating cables, and heating cords have previously been wound. Heating tapes, heating cables, and heating cords can usually be wound with quite tight bending radii. However, care must be taken to ensure that they are not wound too close together or too far apart from one another, on the one hand to prevent overheating of the heating tapes, heating cables, and heating cords, and on the other hand to ensure that the pipes, containers, and fittings are sufficiently heated.This is less of a problem with heated hoses, but they are usually significantly more expensive than heating tapes, heating cables, and heating cords, as the heated hoses must be configured in advance and adapted to the specific application. The winding of the heating wires in heated hoses cannot be varied subsequently, or only to a very limited extent.

[0005] Therefore, the object of the present invention is to design and further develop the heating hose and the methods of the type mentioned at the outset and explained in more detail above in such a way that electrical heating of pipes, containers and molded parts can be carried out more cost-effectively, reliably and at the same time more efficiently.

[0006] This object is achieved in a heating hose according to the preamble of claim 1 in that the heating hose is designed as a shrink hose with a diameter that can be shrunk at least in sections by heating for shrinking onto the pipeline,the container and / or the molded part and that the at least one heating section comprises at least one thermoplastic and at least one electrically conductive filler finely distributed in a matrix of the at least one thermoplastic, and that the at least one electrically conductive heating section is designed to be applied to an electrical heating voltage or an electrical heating current for at least partially shrinking the diameter as a result of heating the at least one heating section and / or for inductively heating the at least one heating section via an alternating magnetic field and for at least partially shrinking the diameter as a result of the inductive heating of the at least one heating section. By designing the heating hose as a shrink hose with at least one heating section comprising finely distributed conductive particles,The heating hose can be easily and quickly retrofitted, in particular pushed onto, various pipes, containers, or molded parts. At the same time, good thermal contact and heat transfer between the heating hose and the object to be heated are ensured if the heating hose is selected in the correct size and with the correct shrinkage factor. After shrinking, the heating hose then fits tightly against the object to be heated. For heating purposes, a conductive filler consisting of small, separate particles is finely distributed in the at least one thermoplastic material in at least one heating section of the heating hose. Shrinking the heating hose therefore cannot damage the heating section.

[0007] Shrinkage, on the other hand, typically reduces the electrical resistance of at least one heating section. This should be considered in advance, if necessary, when determining the quantity and type of conductive particles in the at least one heating section. This should ensure, on the one hand, that the at least one heating section reliably conducts electrical current. On the other hand, a sufficiently large resistance should be offered to the conduction of the electrical current so that a sufficiently large heat flow is generated in the at least one heating section as soon as the heating voltage or current is applied to the heating hose.

[0008] Heating the heating hose by applying a heating voltage or heating current to the heating hose is intended, on the one hand, to heat the heating hose and heat the object enclosed by the heating hose. On the other hand, the initial application of the heating voltage or heating current can heat the heating hose, causing the heating hose to shrink onto the pipe, container, molded part, or the like. For this to happen, a minimum temperature must be exceeded, which is largely determined by the thermoplastic material or materials used. Shrinking the heating hose using a hot air blower is not necessary, so a work step can be eliminated or at least simplified. Nevertheless, it may be possible to shrink the heating hose using a hot air blower.In principle, the heating hose can be supplied with direct current or alternating current for trace heating or for shrinking.

[0009] The above object is further achieved according to claim 12 by a method for producing a heating hose, preferably according to one of claims 1 to 10,

[0010] - in which a raw hose is extruded with at least one heating section comprising at least one thermoplastic material and at least one conductive filler finely distributed in the matrix of the thermoplastic material,

[0011] - in which the diameter of the extruded raw hose is expanded, preferably by stretching, and

[0012] - in which, preferably, the at least one heating section is connected to two electrical contacts for applying an electrical voltage or an electrical current.

[0013] The extrusion of extrudates comprising, on the one hand, at least one thermoplastic and, on the other hand, at least one conductive filler is already known from other applications. In contrast to the known processes, no raw hose is extruded in this case. However, here too, it is important to achieve the most homogeneous mixing of filler and thermoplastic in order to produce a satisfactory heating section of the heating hose. The proportions and ratios of thermoplastic and electrically conductive filler to be used, and how homogeneous the distribution of the electrically conductive filler should be, depend heavily on the thermoplastic and the type of electrically conductive filler used. Furthermore, the particle size, as well as their porosity and surface quality, can be of considerable importance.Nevertheless, the skilled person will be able to provide a suitable extrudate or to further optimize it through a manageable number of tests.

[0014] Once the raw hose has been extruded, it is expanded, which can be done using a stretching process, whereby the raw hose can be stretched in particular in the radial and / or circumferential direction. The raw hose can be heated and stretched while increasing its diameter. The stretched raw hose can be frozen in this form by cooling. So that a heating voltage or heating current can be applied to the heating hose, the at least one heating section can be provided with at least two electrical contacts, via which the at least one heating section can be connected to a voltage or power supply. Cable connection clamps, pipe clamps and band clamps, for example, can be used here. However, instead of clamps, simply point-like, non-circumferential contacts can also be used, which may also be known from other applications.

[0015] If at least one heating section of the heating hose is heated inductively via an alternating magnetic field, corresponding contacts are generally unnecessary. The heating hose can generally be heated inductively both to shrink the heating hose and to heat a pipe, a container, and / or a molded part. Thus, for example, it can be provided to inductively shrink the heating hose and heat the pipe, the container, and / or the molded part by applying an electrical voltage or an electrical current to the contacts of the heating hose.

[0016] Furthermore, the term “clamp” is to be understood very broadly in this case and is intended to include other elements, even if these are not usually referred to as clamps. The clamps are intended to be provided on or in a corresponding section of the heating hose and to make electrically conductive contact with at least one heating section or to electrically connect several heating sections to one another. Circumferential bands, O-rings and the like are also suitable here. The clamps do not have to be made of a metallic material. The clamps can also be made of a plastic containing a finely distributed electrically conductive filler, similar to the actual heating hose itself. The clamp can also be designed as a shrink tube for shrinking onto the actual heating hose, similar to the actual heating hose itself.

[0017] Furthermore, the above-mentioned object is achieved according to claim 16 by a method for shrinking a heating hose, preferably according to one of claims 1 to 11 and / or manufactured according to one of claims 12 to 15,

[0018] - where the heating hose is applied to a pipe, a container and / or a

[0019] mold part is mounted,

[0020] - in which at least two contacts of at least one heating section of the pulled-on heating hose are connected to a heating voltage or a heating current and the heating voltage or the heating current heats the at least one heating section in the form of a heating resistor and / or the at least one heating section is heated inductively via an alternating magnetic field and

[0021] - in which the heating hose is shrunk onto the pipeline, the container and / or the molded part as a result of the heating of at least one heating section, with the diameter being reduced.

[0022] In its expanded form, the heating hose can be easily pulled onto the pipeline, container, and / or molded part due to its enlarged diameter. The corresponding object is then at least partially located in the heating hose, with a certain amount of play preferably existing between the corresponding object and the heating hose. The object is then loosely received in the heating hose. The heating hose is then not yet seated tightly on the object. In order to achieve this at least in sections, the heating hose can be connected to a heating voltage or a heating current with the at least two contacts of the heating section, which heats the heating section, since the heating section is designed as a heating resistor.The (specific) resistance of the heating section is so high that the electrical current flows through the heating section in accordance with the heating voltage or current, generating a high degree of heat. Ultimately, a high degree of electrical energy is dissipated in the heating section and released in the form of heat. However, this heat also leads to the heating hose heating up itself. If a minimum temperature is exceeded, the heating hose attempts to contract back to its original size with a smaller diameter, similar to a shape memory material. This process is also referred to as shrinking. As a result of the shrinkage, the heating hose fits tightly against the pipe, container and / or molded part, which is also referred to as shrinking.

[0023] The heating hose can also be shrunk on inductively by exposing at least one heating section to an alternating magnetic field. An induction coil can be used for this purpose. An induction coil through which an alternating current flows generates a magnetic field that changes direction and is characterized by a magnetic flux. If a heating section is placed in this magnetic field, a voltage is induced in it. The induced voltage creates a current flow (Lenz's law). In the heating section, eddy current losses occur at the conductive particles, which are converted into heat at the conductive particles. In principle, it would also be conceivable to shrink the heating hose by heating it with a hot air blower. The heat is then transferred directly to the heating hose via warm air.This ensures very good and close contact between the heating hose on the one hand and the pipeline, the container and / or the molded part on the other, and thus good heat transfer from the heating hose to the object surrounded by the heating hose. This makes it possible to very precisely control the temperature of the object in question, at least in the corresponding section, without risking local overheating. At the same time, this is also possible very efficiently, as heat losses through air gaps between the object and the heating hose can be avoided. Ultimately, this also eliminates the risk of the heating hose becoming damaged and unusable due to a break in the heating wire installed therein. With the heating hose according to the invention, on the other hand, partial damage to the heating section can be tolerated if the section is sufficiently wide.Then there still remains an electrically conductive connection between the electrical contacts of the heating hose.

[0024] In a first particularly preferred embodiment of the heating hose, the at least one electrically conductive filler is carbon-based and is formed in particular from carbon black and / or graphite. The electrically conductive filler can additionally or in contrast also be formed from metallic particles, with iron and / or copper particles being particularly suitable. Alternatively or additionally, the at least one thermoplastic material can be a polyolefin, in particular polyethylene (PE) or polypropylene (PP), polyamide (PA), fluoroethylene propylene (FEP), polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), Viton, polyvinyl chloride (PVC) and / or polytetrafluoroethylene (PTFE). The physical and in particular the electrical properties of the heating hose are determined to a significant extent by the choice of materials.Therefore, a person skilled in the art can influence the desired physical properties of the heating hose by suitable selection of materials. All of the materials mentioned are available at relatively low, albeit at different costs. The heating hose can be manufactured at least in sections from a raw hose formed by extrusion. This is a very reliable and cost-effective method for forming a heating hose. Alternatively or additionally, the heating hose can be manufactured at least in sections by expanding the diameter of the raw hose produced by extrusion or another method. The expansion can be carried out, for example, in a similar way to blown film production by blowing pressurized air into the raw hose. The raw hose is thereby expanded in the radial direction.The expanded heating hose serves to be pulled onto the pipeline, container, and / or molded part and is therefore expanded to a suitable extent. As an alternative to extrusion, the heating hose can also be formed from a film that has at least one heating section and is joined, in particular welded, at the edges. In this way, a raw hose can also be formed, which can then be further processed in the manner described.

[0025] In order to impart a high degree of shape memory to the heated hose, especially the raw hose, for subsequent shrinkage, it may be advisable for the molecules of the at least one thermoplastic material to be at least partially cross-linked with one another. If this occurs before the diameter is expanded, it can lead to an even more pronounced shape memory. One way to provide cross-linking in a practical, simple, reliable, and reproducible manner is to irradiate the at least one thermoplastic material with electrons. This process is fundamentally known, for example, from plastic film production.

[0026] The diameter of a raw hose can be expanded independently by stretching. The raw hose is stretched radially beyond its elastic yield point, causing the molecules to align in the stretching direction. This alignment results in the molecules being closer together, thus creating stronger forces of attraction between the molecules. Stretching can occur at elevated temperatures, followed by cooling to essentially maintain the alignment of the molecules. If the thermoplastic is subsequently heated, the molecules align themselves more randomly, thus becoming more isotropic, causing the heated hose to contract and thus shrink.

[0027] For some applications, it can be disadvantageous if the heating hose is essentially electrically conductive. In such cases, it can be advisable to form the heating hose with several layers, which can preferably be aligned at least essentially concentrically to one another. The layers are then either concentric or only essentially concentric to one another. A mathematically exact concentric arrangement is therefore not absolutely necessary. If the pipeline, the container and / or the molded part is made of an electrically conductive material, the corresponding object can be prevented from being exposed to electricity when heated with the heating hose if an inner layer is designed to be electrically insulating.The electrically conductive heating section of the heating hose then does not come into direct contact with the electrically conductive pipe, the electrically conductive container and / or the electrically conductive molded part.

[0028] Alternatively or additionally, an outer layer can also be designed to be electrically insulating from the at least one heating section. In this case, the risk of electric shock is reduced, as is the risk of a short circuit. However, it is also impossible for the current from the heating section to be transferred to another object touching the heating hose.

[0029] If the heating hose has contacts assigned to both of its opposite ends for applying the heating voltage or heating current, the heating hose can be supplied with a heating voltage or heating current without complex wiring. In addition, a uniform current density and thus uniform heating of the heating hose can be achieved. In such a case, for these reasons, it may also be advisable if the at least one heating section is provided all the way around and / or over at least substantially the entire longitudinal extent of the heating hose. The at least one heating section can therefore be provided over the entire longitudinal extent of the heating hose or also only over at least substantially the entire longitudinal extent of the heating hose. It can therefore be functionally harmless if the at least one heating section does not extend entirely over the entire longitudinal extent of the heating hose.

[0030] Alternatively or additionally, the heating hose can also have at least two heating sections that are electrically separated from one another circumferentially at least over approximately the entire longitudinal extent. The heating sections can therefore be electrically separated from one another circumferentially only over approximately the entire longitudinal extent or preferably electrically separated from one another circumferentially over the entire longitudinal extent. Here and below, "circumferential" can generally be understood as along the circumference or in the circumferential direction. In this way, it can be achieved that the current flows in different directions, in particular in opposite directions, for example in the longitudinal direction or in the circumferential direction, in the at least two separate heating sections.This ultimately allows the heating hose to be connected to the heating voltage or heating current from one side via corresponding contacts on the at least two separate heating sections. Depending on the length of the heating hose, this can save a considerable amount of cable length for connecting the heating hose. However, this is not necessary. At least two heating sections extending in the longitudinal direction can also be provided, which are nevertheless provided with contacts for applying a heating voltage or heating current at opposite longitudinal ends. Alternatively or additionally, each heating section can be assigned a contact. At the opposite end with respect to the electrical contacts and the connection of the heating voltage or heating current, the at least two heating sections can be electrically connected to one another in order to close the corresponding circuit.For simplicity, the at least two heating sections can be connected to each other via an electrically conductive clamp, which is provided in contact with the heating sections. The clamp should then be electrically conductive at least to such an extent that the at least two heating sections are electrically connected to each other via the clamp.

[0031] As already mentioned, the term "clamp" can be understood very broadly in this context. If necessary, the term "clamp" also includes elements that are not usually referred to as clamps. The clamps should be provided on or in a corresponding section of the heating hose and electrically contact at least one heating section or electrically connect several heating sections to one another. In particular, circumferential bands, O-rings and the like are also suitable here. The clamps do not have to be made of a metallic material. The clamps can also be made of a plastic that contains a finely distributed electrically conductive filler, similar to the actual heating hose itself. The clamp can also be designed as a shrink tube for shrinking onto the actual heating hose, similar to the actual heating hose itself.

[0032] In the case of at least two heating sections, at least two contacts for applying the heating voltage or current can be assigned to one longitudinal end of the heating hose. Supplying the heating voltage or current to the heating hose from one side may then be sufficient. For the sake of simplicity, one contact can be assigned to each heating section to eliminate unnecessary contacts and wires.

[0033] The at least two heating sections can also be connected to one another via at least two connecting sections, wherein the connecting sections can extend at least substantially over the entire longitudinal extent of the heating hose. The connecting sections can have an electrical conductivity which means that the connecting sections can be regarded, at least in principle, as being electrically connected in parallel. If the connecting sections have a significantly, in particular very much, lower resistance than the heating sections, the heating hose can be regarded in an equivalent circuit diagram as a parallel connection of the heating resistors of the heating sections. Thus, the heating resistance of the heating sections can decrease with increasing length of the heating hose. The power relative to the length of the heating hose then increases with increasing length of the heating hose.With series-connected heating resistors of the heating sections, however, the heating resistance can increase with the length of the heating hose, and the power per length of the heating hose decreases. Therefore, in such a series connection, the heating resistors of the heating sections should be specifically adjusted to provide the desired length-specific power. Connecting the heating resistors in parallel is more practical in terms of the manufacturing and use of the heating hoses. The power per length of the heating hose is then not limited for a given power source voltage.

[0034] For this purpose, the connecting sections, in contrast to the heating sections, are so low-resistance that no significant or very low, in particular negligible, heat flow is generated in the connecting sections compared to the heating sections. The specific resistances of the at least two heating sections can therefore each be at least twice as large, preferably at least five times as large, in particular at least ten times as large, as the specific resistances of the at least two connecting sections.

[0035] Alternatively or additionally, the at least two connecting sections can be co-extruded with the heating sections. The conductivity of the connecting sections can then be specifically adjusted in this area by introducing conductive fillers into the matrix of a thermoplastic. However, this may not necessarily be the same thermoplastic and / or filler as in the heating sections, if required. Alternatively or additionally, at least one metallic wire, a metallic strip, and / or a metallic wire mesh can also be provided in the connecting sections. The wire, the metallic strip, and / or the wire mesh can be provided in the thermoplastic of the connecting section or can be used up on it, for example after the co-extrusion of the heating hose and / or raw hose.The increased conductivity in the area of ​​the connecting sections can alternatively or additionally be achieved by applying a conductive coating, in particular in the form of a paint, to the area of ​​the connecting sections.

[0036] To enable heating of the pipeline, container, and / or molded part that varies over the circumference of the heating hose, the at least one heating section can be provided circumferentially over a length of less than 70%, preferably less than 50%, in particular less than 30% of the circumference. The remaining part of the circumference of the heating hose can then be formed in an insulating manner or partially by at least one further heating section.

[0037] In a first particularly preferred method for producing a heating hose, the raw hose can be coextruded from at least two different extrudates, wherein at least one extrudate contains no electrically conductive filler. A longitudinally extending, electrically non-conductive, non-heating section and / or an inner and / or outer circumferential, electrically non-conductive non-heating section can then be coextruded with the at least one extrudate containing at least substantially no electrically conductive filler.

[0038] If a section formed with the non-conductive extrudate extends in the longitudinal direction of the heating hose, corresponding areas can be specifically excluded from heating. If at least two such longitudinally extending sections of the heating hose are provided, these can circumferentially separate two separate, electrically conductive heating sections, allowing the current in these heating sections to flow in different, particularly opposite, directions.

[0039] By coextruding an inner, circumferential non-heating section, such as a non-heating layer, electrical insulation can be provided between the heating hose and the object enclosed by the heating hose for heating. If an outer, circumferential non-heating section, such as a non-heating layer, is additionally or alternatively provided, reliable electrical insulation of the heating hose is achieved from any electrically conductive objects that may be in contact with the outside of the heating hose. This is preferred, for example, for safety reasons and / or to prevent short circuits.

[0040] Alternatively or additionally, two heating sections extending longitudinally and circumferentially at least substantially separated from each other can be coextruded from at least one extrudate with at least one electrically conductive filler. Thus, the current can flow in one direction in one heating section and in the other direction in the other heating section to provide varying current densities and / or to enable connection of the heating hose to the heating voltage or current on only one side.

[0041] In order to electrically connect the at least two heating sections, a circumferential clamp or another, in particular circumferential, connection can be provided, which is at least partially electrically conductive and there contacting the heating sections, at least in the connection area between two circumferentially adjacent heating sections. A raw hose previously produced, in particular by extrusion, can be irradiated with electrons before the raw hose is expanded in such a way that molecules of the thermoplastic material crosslink with each other. In this way, the raw hose can be given a certain shape memory for later shrinkage. Alternatively, the raw hose can be heated before expansion and cooled after expansion. In this case, too, the raw hose can be given a certain shape memory.When heated again, the heating tube contracts and can be shrunk onto an object. This principle is familiar from the production of electrically insulating heat-shrink tubing.

[0042] The invention is explained in more detail below with reference to a drawing which merely illustrates exemplary embodiments. The drawing shows

[0043] Fig. 1A-B show a method according to the invention for producing a heating hose according to the invention and a method according to the invention for shrinking the heating hose, each in a schematic representation,

[0044] Fig. 2 shows a second heating hose according to the invention in a perspective side view,

[0045] Fig. 3 shows a third heating hose according to the invention in a perspective side view,

[0046] Fig. 4 shows a fourth heating hose according to the invention in a perspective side view,

[0047] Fig. 5 shows a fifth heating hose according to the invention in a perspective side view and Fig. 6A-C shows a sixth heating hose according to the invention in a perspective side view, an equivalent circuit and a perspective sectional view.

[0048] Fig. 1A shows a method for producing a heating hose 1. In this method, a raw hose 7 is first extruded through a corresponding nozzle 6 by means of an extruder 2 and an extrudate 3 comprising a thermoplastic 4 and a particulate filler 5 made of electrically conductive, fine particles. The electrically conductive particles of the filler 5 are either finely distributed in the thermoplastic 4 in the extruder 2, or a raw material made of a thermoplastic 4 in which the filler 5 is already present in finely distributed form is fed to the extruder 2. The raw hose 7 extruded in this way then has a matrix made of the thermoplastic 4 as a continuous phase, in which the particulate filler 5 made of electrically conductive particles at least in sections is finely distributed as a disperse phase.The raw hose 7 is therefore electrically conductive, whereby the electrical conductivity of the raw hose 7 is distributed very homogeneously in the raw hose 7 or the corresponding heating section 8.

[0049] After extrusion, the raw hose 7 is moved through or inserted into an irradiation device 9, in which the raw hose 7 is irradiated with electrons. Irradiation of the raw hose 7 causes molecules of the thermoplastic material 4 to crosslink with one another. Corresponding irradiation devices 9 are generally known from other applications. The fully crosslinked raw hose 7 is cut to size in the illustrated and, in this respect, preferred method and subsequently heated by means of an external heat source 10. The thus heated raw hose 7 is subsequently stretched, i.e., drawn, in the radial direction according to the arrows shown beyond its elastic yield point. In the process, the diameter d of the extruded raw hose 7 increases to the diameter D of the correspondingly expanded heating hose 1.The heating hose 1 is then cooled in its expanded state by means of a cooling device 11 and provided with electrical contacts 12. The ratio of the diameters d and D represents the shrinkage factor of the heating hose 1, which may or may not correspond to the diameter ratio. Whether this is the case is determined by whether the heating hose 1, when not pulled onto an object, could theoretically shrink to the diameter d of the raw hose 7.

[0050] However, the heating hose 1 does not necessarily have to be provided with electrical contacts 12. This can be useful for pre-assembly and easier, later installation of the heating hose 1. The contacts 12 should then preferably be permanently attached to the heating hose 1. In other cases, however, it may also be desirable to attach the contacts 12 only after assembly or shortly before assembly of the heating hose 1. In such a case, the final length of the heating hose 1 acting as a heating resistor can be determined on-site and thus very precisely. For example, the heating hose 1 is shortened to the exact required length on-site and then fitted with contacts at the opposite ends.

[0051] 12 or only at one end with a contact 12.

[0052] The thus-finished heating hose 1 can then be transported to its place of use, where the heating hose 1 is pushed onto a pipe 13 in the preferred method shown in Fig. 1B. The pipe

[0053] 13 has a tube diameter R that is larger than the diameter d of the raw hose 7 but at the same time significantly smaller than the diameter D of the heating hose 1 in the expanded state. In a next step, the heating hose 1 is connected via the electrical contacts 12 to a voltage or current source 14, with which a heating voltage or a heating current is applied to the heating hose 1. In principle, both a direct voltage and an alternating voltage can be applied. The heating hose 1 is essentially formed by a conductive heating section 8, the conductivity of which is brought about by the conductive particles of the filler 5 finely distributed in the thermoplastic material 4.However, the resistance of heating section 8 is so high that the heating voltage or current applied to heating hose 1 generates heat so high that heating hose 1 is heated to such a high temperature that it contracts on its own, thus shrinking, as is known from electrically non-conductive heat-shrink tubing. Heating hose 1 shrinks to such an extent that it is shrunk tightly onto pipe 13, ensuring full surface contact.

[0054] The heating hose 1 shrunk onto the pipe 13 in this way can be provided with a heating voltage or a heating current as desired in the future, although this does not lead to further shrinkage of the heating hose 1, but merely to heat development and heating of the pipe 13. Thus, the pipe 13 can be heated from the outside by applying a suitable voltage or a suitable current to the heating hose 1 in the sense of trace heating.

[0055] If necessary, the heating hose 1 can also be shrunk without applying an electrical voltage or an electrical current to the heating section 8 via the contacts 12 of the heating hose 1. Instead, the heating hose 1 can be shrunk inductively without contact by applying an alternating magnetic field. The alternating magnetic field induces a voltage in the heating section 8, which leads to eddy current losses, which heats up the heating hose 1. Once a sufficient temperature is reached, the heating hose 1 shrinks in a similar way to applying a voltage or current to the contacts 12 of the heating hose 1. A sufficient temperature can also be achieved by applying hot air from a hot air blower to the heating hose 1.

[0056] Fig. 2 shows a perspective view of a heating hose 20, wherein the heating hose 20 is pulled onto a pipe 13 and shrunk onto it. The heating hose 20 is formed from a continuous layer of a mixture of a thermoplastic material 4 and an electrically conductive, particulate filler 5 finely distributed therein. The heating hose 20 therefore forms a heating section 21 that is continuous both in the longitudinal direction and in the circumferential direction. The entire heating section 21 and thus the entire heating hose 20 can therefore be flowed through by a heating current from one side to the other when the heating hose 20 is connected to a heating voltage or a heating current.For this purpose, the opposite longitudinal ends of the heating section 21 in the illustrated and, in this respect, preferred heating hose 20 are provided with circumferential clamps 22, which are connected to a voltage supply or power supply for applying the heating voltage or heating current. The heating current thus flows through the heating section 21, generating heat, which is transferred to the pipe 13 partially enclosed by the heating hose 20. In this way, a medium flowing through the pipe 13 can be heated.

[0057] Fig. 3 shows a perspective view of another heating hose 23, although for the sake of clarity, an additional pipe has been omitted. The heating hose 23 is made from a coextruded raw hose. Four different regions are created on the circumference by coextrusion. Two of these regions are heating sections 24, which comprise a thermoplastic 4 and an electrically conductive filler 5 finely distributed therein. The heating sections 24 are electrically conductive and can serve as heating resistors. Two further regions are electrically non-conductive non-heating sections 25. These non-heating sections 25 are therefore not suitable as heating resistors.Although it cannot be ruled out that the non-heating sections 25 comprise an electrically conductive filler 5, the proportion of the filler 5 is so small and its resistance so high that the non-heating sections 25 practically do not conduct the electrical current.

[0058] The heating sections 24 and the non-heating sections 25 are provided circumferentially alternating with one another, so that the heating sections 24 are separated circumferentially by the non-heating sections 25. In the illustrated and in this respect preferred heating hose, the heating sections 24 and the non-heating sections 25 extend with at least substantially constant width over at least substantially the entire length of the heating hose 23. At one longitudinal end of the heating hose 23, a clamp 26 is provided, which is electrically conductive and contacts the heating sections 24 on the one hand and electrically conductively connects them to one another on the other. At the end of the heating hose 23 opposite the clamp 26, an electrical contact TI is provided on each heating section 24, which can be connected to the one voltage or current source 14 for applying the heating voltage or the heating current.In this case, the heating current flows through one heating section 24 to the clamp 26 and through the clamp 26 into the other heating section 24, in order to flow back to the voltage source 14 in this heating section 24. Heat is generated, which can be transferred to the object accommodated at least partially in the heating hose 23.

[0059] For example, a band or O-ring made of a plastic that is conductive at least in sections around its circumference could also be used as a clamp. The plastic can therefore have an electrically conductive, finely distributed filler at least in the corresponding areas. If necessary, the band can have the same plastic and / or the same filler as the rest of the heating hose 1. The circumferential band could also be designed as a shrink tube like the actual heating hose and, together with the actual heating hose 1, be shrunk onto the pipe 13 or another object to be heated. It would also be conceivable for an end piece of the heating hose 1 to be cut off, for example rotated by 90°, and pulled over the corresponding end of the heating hose 1 in order to form a clamp for the electrically conductive connection of the heating sections 24 at this end of the heating hose.The term "clamp" can therefore be understood very broadly if necessary and is used here as a kind of general umbrella term for the sake of better comprehensibility, also to avoid unnecessary repetition. It is understood in this context that, instead of the clamp 26, another means can also be provided to connect the heating sections 24 to one another in sections. These means can also be integrated into the hose material, for example by providing a sufficient amount of electrically conductive filler 5 there, similar to the heating sections 24. It is also conceivable that more than two heating sections 24 and, accordingly, several non-heating sections 25 are provided between them.

[0060] Fig. 4 shows a heating hose 30 which has a heating section 31 and a non-heating section 32 over the circumference of the heating hose 30. The heating section 31 and the non-heating section 32 are designed in principle like the heating sections 24 and the non-heating sections 25 of the heating hose 23 according to Fig. 3. The heating section 31 and the non-heating section 32 extend over the entire longitudinal extent of the heating hose 30 and each form a part of the circumference of the heating hose 30. The electrical contacts 22 are attached to the opposite ends of the heating section 31 in order to be able to apply a heating voltage or a heating current to the heating hose 30.Since the heating section 31 in the illustrated and in this respect preferred heating hose 30 is only provided over approximately half of the circumference, a pipeline can be heated by means of the heating hose 30 specifically from one side, but not also from the other side, if this should be desirable.

[0061] Fig. 5 shows a heating hose 33 formed from three concentrically arranged layers 34, 35, 36, which are all firmly connected to one another. For this purpose, the three layers 34, 35, 36 are preferably formed together by coextrusion. The inner and outer layers 34, 36 are designed over their entire circumference as non-heating sections 37, which can also be referred to as non-heating layers. The inner layer 34 and the outer layer 36 have so little electrically conductive filler 5 that these two layers 34, 36 do not conduct, or conduct almost nothing, the electrical current applied to the middle layer 35 of the heating hose 33.The inner layer 34 and the outer layer 36 thus act as electrical insulation with respect to the middle layer 35, which in the illustrated and in this respect preferred heating hose 33 is formed over its entire circumference as a heating section 38, which can also be referred to as a heating layer.

[0062] However, this is not absolutely necessary. For example, the middle layer 35 could contain several heating sections 38 and one or more non-heating sections 37. It is also conceivable for there to be several middle layers 35 which are designed differently from one another with regard to the heating section 38 or sections 38. Alternatively or additionally, the inner layer 34 (non-heating layer) or the outer layer 36 (non-heating layer) could be omitted. In the heating hose 33 shown, only the inner layer 35 (heating layer) conducted the electrical current. Thus, heat is only generated in the inner layer 35 by dissipating electrical energy. However, the heat can still be used, for example, to heat a pipe 13 without applying an electrical current to it. The heat is also sufficient to shrink the heating hose onto the pipe 13.

[0063] Fig. 6A shows a perspective view of another heating hose 40. The heating hose 40 is made, for example, from a coextruded raw hose. Four different regions are created on the circumference during the coextrusion process. Two of these regions are heating sections 41, which comprise a thermoplastic 4 and an electrically conductive filler 5 finely distributed therein. The heating sections 41 are electrically conductive and can serve as heating resistors. Two further regions are connecting sections 42 with a significantly lower electrical resistance compared to the heating resistors of the heating sections 41. The connecting sections 42 therefore do not form a heating resistor of the heating hose 40. The connecting sections 42 are each provided with a contact 43 for connection to a heating voltage or a heating current via the voltage or current source 14.In the illustrated and preferred heating hose 40, the contacts 43 are provided at the same longitudinal end of the heating hose 40 for the sake of simplicity. Due to the low electrical resistance of the connecting sections 42 compared to the heating sections 41, the connecting sections 42, unlike the heating sections 41, do not act as heating resistors, but rather connect the heating sections in parallel to the voltage or current source 14.

[0064] The heating sections 41 and the connecting sections 42 are provided circumferentially alternating with one another, so that the heating sections 41 are separated circumferentially by the connecting sections 42. In the illustrated and thus preferred heating hose 40, the heating sections 41 and the connecting sections 42 extend with at least a substantially constant width over at least substantially the entire length of the heating hose 40.

[0065] In this case, the heating current flows in the longitudinal direction of the heating hose 40 through the connecting sections 42 and in the circumferential direction through the heating sections 41. The heating hose 40 connected to the voltage or current source 14 via the contacts 43 can be represented as an equivalent circuit diagram according to Fig. 6B, in which the heating resistors RH of the heating sections 41 are arranged parallel to the voltage or current source 14.

[0066] Fig. 6C shows the heating hose 40 in a perspective sectional view through the opposing connecting sections 42. This shows the length LS of the heating hose 40, the length LW of a heating resistor of a heating section 41, and the thickness D of the heating hose 40. The heating resistance RH of a heating section 41 is calculated as follows: RH = r * LW / A = r * LW / (D * LS), where U is the voltage of the voltage source 14, r is the specific resistance of the heating section 41, and A is the cross-sectional area of ​​the heating resistor or heating section. The electrical power P when the heating resistors RH of the heating hose 40 are connected in parallel is therefore calculated as follows:

[0067] P = 2 * U 2 / RH = 2 * U 2 * A / (r * LW) = 2 * U 2 * D * LS / (r *LW).

[0068] Thus, the heating resistance RH of the heating hose 40 decreases with the length LS of the heating hose 40, and the power P increases with the length LS of the heating hose 40. The power P relative to the length LS of the heating hose 40 is therefore not limited for a given voltage U of the power source 14.

[0069] The connecting sections 42 of the heating hose 40 are manufactured by coextrusion with the heating sections 41. To provide sufficient conductivity, the connecting sections 42 can have a higher concentration of electrically conductive filler 5 than the heating sections 41 and / or a more conductive filler than the filler 5 of the heating sections 41. Wires and / or metal mesh can also be introduced into the connecting sections 42. Metallic strips can also be introduced into the thermoplastic material of the connecting sections 42, wherein the metallic strips, wires, and / or wire mesh can also be applied to the coextruded regions of the connecting sections 42. The conductivity can also be provided by a conductive coating, in particular a conductive paint, of the coextruded regions of the connecting sections 42.

[0070] List of reference symbols

[0071] 1 heating hose

[0072] 2 Extruder 3 Extrudate

[0073] 4 Plastic

[0074] 5 Filler

[0075] 6 nozzle

[0076] 7 Raw hose

[0077] 8 heating sections

[0078] 9 Irradiation facility

[0079] 10 Heat source

[0080] 11 Cooling device

[0081] 12 Contact

[0082] 13 Pipeline

[0083] 14 Voltage or current source

[0084] 20 heating hose

[0085] 21 heating section

[0086] 22 Contact

[0087] 23 Heating hose

[0088] 24 heating sections

[0089] 25 non-heating sections

[0090] 26 clamp

[0091] 27 Contact

[0092] 30 heating hose

[0093] 31 heating section

[0094] 32 Non-heating section

[0095] 33 Heating hose

[0096] 34 inner layer

[0097] 35 middle layer

[0098] 36 outer layer

[0099] 37 Non-heating section

[0100] 38 heating sections

[0101] 40 heating hose

[0102] 41 heating section

[0103] 42 connecting section

[0104] 43 Contact d Diameter raw hose

[0105] D Diameter of heating hose

[0106] R pipe diameter

Claims

Heating hose (1, 20, 23, 30, 33, 40) for electrically heating a pipeline (13), a container and / or a molded part from the outside, with at least one electrically conductive heating section (21, 24, 31, 38, 41) in the form of a heating resistor for at least partially heating the heating hose (1, 20, 23, 30, 33, 40), characterized in that the heating hose (1, 20, 23, 30, 33, 40) is designed as a shrink hose with a diameter (D) that can be shrunk at least partially by heating for shrinking onto the pipeline (13), the container and / or the molded part, and in that the at least one heating section (21, 24, 31, 38, 41) comprises at least one thermoplastic material (4) and at least one electrically conductive filler (5) finely distributed in a matrix of the at least one thermoplastic material (4). and that the at least one electrically conductive heating section (21, 24, 31, 38,41) for applying an electrical heating voltage or an electrical heating current for at least partially shrinking the diameter (D) as a result of heating the at least one heating section (21, 24, 31, 38, 41) and / or for inductively heating the at least one heating section (21, 24, 31, 38, 41) via an alternating magnetic field and for at least partially shrinking the diameter (D) as a result of the inductive heating of the at least one heating section (21, 24, 31, 38, 41). Heating hose according to claim 1, characterized in that the at least one electrically conductive filler (5) is carbon-based, in particular carbon black and / or graphite, and / or by metallic particles, preferably iron and / or copper particles, and / or that the at least one thermoplastic material (4) is a polyolefin, in particular polyethylene (PE) or polypropylene (PP), polyamide (PA), fluoroethylene propylene (FEP), polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), Viton, polyvinyl chloride (PVC) and / or polytetrafluoroethylene (PTFE).

3. Heating hose according to claim 1 or 2, characterized in that the heating hose (1, 20, 23, 30, 33, 40) is made at least in sections from a raw hose (7) formed by extrusion and / or that the heating hose (1, 20, 23, 30, 33, 40) is made at least in sections by widening the diameter (d) of a raw hose (7) for pulling onto the pipeline (13), the container and / or the molded part.

4. Heating hose according to claim 3, characterized in that molecules of the at least one thermoplastic material (4), in particular before an expansion of the diameter (d), are cross-linked with one another and that, preferably, the cross-linking of the molecules of the at least one thermoplastic material (4) has taken place by means of electron irradiation.

5. Heating hose according to claim 3 or 4, characterized in that the diameter (d) of the raw hose (7) is widened by stretching.

6. Heating hose according to one of claims 1 to 5, characterized in that the heating hose (7) has a plurality of at least substantially concentric layers (34, 35, 36) and that an inner layer (34) and / or outer layer (36) with respect to the at least one heating section (38) is designed to be electrically insulating with respect to the at least one heating section (38). Heating hose according to one of claims 1 to 6, characterized in that the heating hose (20, 30, 33) has contacts (22) assigned to its two opposite ends for applying the heating voltage or the heating current, and in that, preferably, the at least one heating section (21, 31, 38) is provided circumferentially and / or over at least substantially the entire longitudinal extent of the heating hose (20, 30, 33). Heating hose according to one of claims 1 to 7, characterized in that the heating hose (23, 40) has at least two heating sections (24, 41) that are electrically separated from one another at least over approximately the entire longitudinal extent, and in that, preferably, the heating hose (23, 40), in particular assigned to one longitudinal end, has at least two contacts (27, 43) for applying the heating voltage or the heating current, and / or a contact (27, 43) is assigned to each heating section (24, 41).Heating hose according to claim 8, characterized in that the at least two heating sections (24) are assigned to a longitudinal end, preferably connected to one another by a circumferential clamp (26) that is electrically conductive at least in sections, or in that the at least two heating sections (41) are electrically connected to one another in parallel by means of at least two electrically conductive connecting sections (42) that extend at least substantially over the entire longitudinal extent of the heating hose (40). Heating hose according to claim 9, characterized in that the specific resistances of the at least two heating sections (42) are each. at least twice as large, preferably at least five times as large, in particular at least ten times as large, as the specific resistances of the at least two connecting sections (42) and / or that the at least two connecting sections (42) are co-extruded with the at least two heating sections (41), have at least one wire, band and / or wire mesh and / or are formed by a conductive coating, in particular painting.

11. Heating hose according to one of claims 1 to 10, characterized in that the at least one heating section (24, 31, 41) is provided circumferentially over a length of less than 70%, preferably less than 50%, in particular less than 30%, of the circumference.

12. A method for producing a heating hose (1, 20, 23, 30, 33, 40), preferably according to one of claims 1 to 11, in which a raw hose (7) with at least one heating section (21, 24, 31, 38, 41), comprising at least one thermoplastic (4) and at least one conductive filler (5) finely distributed in the matrix of the thermoplastic (4) is extruded, in which the diameter (d) of the extruded raw hose (7) is widened, preferably by stretching, and in which, preferably, the at least one heating section (21, 24, 31, 38, 41) is connected to two electrical contacts (22, 27, 43) for applying an electrical voltage or an electrical current.

13. Method according to claim 12, in which the raw hose (7) is co-extruded from at least two different extrudates (3) and in which at least one extrudate (3) does not have an electrically conductive filler (5) and in which a longitudinally extending electrically non-conductive non-heating section (32, 37) and / or an inner and / or outer circumferential, electrically non-conductive non-heating section (37) is co-extruded with the at least one extrudate (3) which does not have an electrically conductive filler (5).

14. The method according to claim 13, wherein at least two heating sections (24) extending in the longitudinal direction are co-extruded from at least one extrudate (3) with at least one electrically conductive filler (5), and wherein, preferably, the at least two heating sections (24) are connected in an electrically conductive manner on the circumference, in particular with a circumferential clamp (26).

15. Method according to one of claims 12 to 14, in which the raw hose (7) is irradiated with electrons after extrusion and before expansion in such a way that molecules of the thermoplastic material (4) are cross-linked with one another and / or in which the raw hose (7) is heated before expansion and cooled after expansion.

16. Method for shrinking a heating hose (1, 20, 23, 30, 33, 40), preferably according to one of claims 1 to 11 and / or manufactured according to one of claims 12 to 15, in which the heating hose (1, 20, 23, 30, 33, 40) is pulled onto a pipeline (13), a container and / or a molded part, in which at least two contacts (22, 27, 43) of at least one heating section of the pulled-on heating hose (1, 20, 23, 30, 33, 40) are connected to a heating voltage or a heating current and the heating voltage or the heating current supplies the at least one heating section (21, 24, 31, 38, 41) in the form of a Heating resistor and / or the at least one heating section (21,24,31,38,41) is heated inductively via an alternating magnetic field and in which the heating hose (1,20,23,30,33,40) is shrunk onto the pipeline (13), the container and / or the molded part as a result of the heating of the at least one heating section (21,24,31,38,41) while reducing the diameter (D).

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