Patent Description:
The invention also relates to a device for performing the method of moulding a multi-layer hose, which comprises a mould in which a longitudinal shaping groove is formed whose cross-section profile is adapted to receive a heated hose for spatial shaping, whereby the mould has smaller radii for the individual bends of the hose than are the final desired radii of the individual bends of the hose and, furthermore, the mould has angles for the individual bends of the hose greater than the final desired angles of the individual bends of the hose.

Multi-layer hoses are used in numerous industries, the outer layer of which is made of rubber or gum, hereinafter referred to as "rubber" (meaning either rubber or gum). Such a multi-layer hose further comprises at least one inner layer which is significantly thinner than the outer rubber layer, whereby this inner layer or these inner layers ensure resistance of the hose to substances passing through it. Typical application areas of multi-layer hoses with an outer rubber layer are the automotive industry and general transportation technology, where such multi-layer hoses are used to carry fuel, engine coolants, refrigerants in air conditioning units, are used in heating systems, etc. Specifically, these hoses are advantageous for their basic flexibility (which is, however, limited and therefore it is extremely to shape them in a car into the desired path between the other car components), and also for their high resistance both from the outer side, i.e. from the side of the outer rubber layer and the inner side, i.e. on the side of the substance that is conveyed through these hoses. However, many applications of multi-layer hoses with a rubber or gum outer layer in the automotive industry or in transportation technology, require the hose to be spatially shaped over its length before being mounted in a vehicle structure, often in a very complicated manner, so that the hose can be incorporated into the structure of the other parts of the automobile.

Document <CIT> (equivalent to document <CIT>) discloses the shaping of hoses having two or more layers, especially for the automotive industry, which are designed for carrying fuel and other fluids in an automobile. The solution described in <CIT> (<CIT>) consists in that the hose ends are secured by clamping means in the machine, whereby these clamps contain conduits for the intake and exhaust of a heating medium and cooling medium to the interior of the hose and also comprise closures for closing the interior of the hose after pressurizing the heating medium inside the hose, as will be described in more detail below. The machine further comprises a heating medium reservoir, a cooling medium reservoir and pumps for conveying both media through the interior of the hose, whereby the pump of the heating medium is adapted to pressurize the interior of the hose with the heating medium to a desired pressure value so that the heating medium can serve as an inner mandrel for subsequent hose shaping which ensures the stability of the hose shape even in bends. Both clamping means of the hose ends are mounted on a positioning device, whereby the length of the hose clamped between the two clamping means is associated with a system of forming benders, movable in the space. The hose clamped between the two clamping means is first heated from the inside by the passage of the heating medium to a temperature which enables to shape the entire hose, whereupon the inner space of the hose is pressurized with the heating medium and closed, so that the heating medium acts as an inner mandrel on the inner walls of the hose and allows retaining the circular cross-section of the hose even in bends. After being heated and pressurized, the hose which is still clamped by the ends in the clamping means is spatially shaped by the spatial movement of the clamping means and movable benders to assume the desired shape. Subsequently, the pressure of the heating medium from the interior of the hose is released and the cooling medium starts to flow into the inner space of the hose, thereby cooling the hose from the inside. After cooling, both ends of the hose are released from the clamping means and the shaped hose is removed from the machine as a finished product.

The disadvantages of the solution according to <CIT> consist first of all in the extreme complexity of the device, which must comprise a large number of spatially precisely movable nodes and benders, whereby in addition, the clamping means of the hose end must allow the intake and delivery of the heating medium and the cooling medium, as well as pressurizing the inner space of the hose with the heating medium to the required high pressure for the subsequent shaping process. Another drawback is the use of excess pressure of the heating medium inside the hose so as to retain the circular cross-section of the hose in bends, which is completely insufficient and unreliable and, what is more, there is a high risk of damage to the inner layers of the hose. A further disadvantage is the fact that the solution does not make provisions for the interaction of the individual layers of the hose, especially the effect of the thicker outer rubber layer on the final shape of the shaped hose.

Furthermore, known are processes for the spatial shaping of single-layer hoses, particularly of non-vulcanized rubber or gum, which are cold elastic, wherein in this state, applying some force, they are inserted into a mould in the form of a labyrinth in which the originally straight hose is brought into the desired shape. Subsequently, the thus preformed hose is heated to the required vulcanization temperature either from the inside by the action of hot steam, or from the outside (in a furnace or by infrared radiation, etc.). After that the hose is allowed to cool in the mould or is actively cooled in the mould, whereby the originally straight non-vulcanized rubber or gum hose permanently retains the spatial shape of the mould, since vulcanization of the rubber or gum takes place only after the hose has been fixed in the spatial shape of the mould. The disadvantage of these solutions is the necessity of using a hose with non-vulcanized outer rubber or gum, whereby the multi-layer hoses with a non-vulcanized outer rubber or gum layer are practically not produced. Moreover, the vulcanization temperature of the rubber or gum, which is significantly higher than the safe temperature for special inner layers of multi-layer hoses, would damage these special inner layers of multi-layer hoses.

Also known is the spatial shaping of multi-layer hoses with an outer layer of vulcanized rubber or gum which are less elastic when cold. This type of hose is heated by external heating, an auxiliary mandrel is inserted because in the inner space of the hose already during the heating, serving to ensure the circular cross-section of the hose even after bending. The hose is heated, e.g., in a furnace or by a thermal radiator (IR radiator) to a temperature of about <NUM> ° C. The heated hose, which is now more elastic, by applying some force is inserted into the mould in the form of a labyrinth in which the originally straight multi-layer hose is brought into a shape which is significantly (fundamentally) different from the final desired hose shape, see <FIG>. Subsequently, the hose is left in the mould to cool or is actively cooled in the mould, and after removal of the hose from the mould, especially due to the elasticity of the outer rubber or gum layer, the shape of the hose changes considerably in contrast to the shape of the mould and assumes the final desired multi-layer hose shape.

However, the disadvantage of this solution is a very large change in the shape of the hose after its removal from the mould due to the impact of the outer rubber or gum layer, which requires extreme differences of the mould from the final form of the hose, extremely small radii and rounding between the individual sections of the mould for the correct final shaping of the individual sections of the finished hose. Therefore, it is very often practically impossible to realize the desired bends with the desired resulting radii, inclinations etc., especially if the ratio of the desired radius or transition or inclination or to the diameter of the shaped hose is unfavorable or too small. Furthermore, the internal heating of the hose cannot be applied here, because it would not be possible to use it together with the mandrel (it prevents heating the inner layer of the hose), or the inner layer of the hose would be damaged by the pressure of the spring mandrel on the wall of the inner layer of the hose.

<CIT> describes a method of manufacturing a molded hose using special apparatus. Flexible mandrel made of rubber or resin with the innermost inner resin layer is fed into the intermediate rubber tube layer extruder, and the intermediate rubber tube layer is continuously extruded and laminated on the outside of the inner resin layer. Then, this outer rubber layer is continuously extruded and laminated by the outer rubber layer extruder on the outer surface of the reinforcing layer to form a straight, long, non-vulcanized hose. The outer rubber layer is continuously extruded and laminated by the outer rubber layer extruder onto the outer reinforcement layer. The hose is then placed in an oven and vulcanized at a temperature of <NUM> degrees Celsius for <NUM> to <NUM> minutes, after which the mandrel is removed and the vulcanized hose body is formed. The long, vulcanized hose body thus obtained is then wound onto a winding drum of a containment device and stored therein. A sealing plug is attached to the end of the hose body and a pressurizing means equipped with a pressure regulator can be used to adjust the pressure of the hose body. The pressurizing means, equipped with an adjustable pressure regulator, pressurizes the inner plastic layer of the hose body from its rear end. A pressurizing pressure of <NUM> to <NUM> kgf/cm2 is preferred, since a pressure of <NUM> kgf/cm2 or less causes wrinkling of the resin in the inner resin layer, while a pressure of <NUM> kgf/cm2 or more expands the inner diameter of the hose body. After the pressurization is completed, the hose body is continuously and sequentially fed to the heating device while pulling the end of the hose body with a string or the like to soften the resin of the inner resin layer. For example, if the inner resin layer is made of nylon resin, it is heated at around <NUM>° C for <NUM> to <NUM> minutes. At this time, the pressure inside the inner resin layer rises due to the heating, but the pressure regulator of the pressurizing means connected to the rear end of the hose body keeps the internal pressure constant, so that the resin surface inside the inner resin layer is always pressurized uniformly at a predetermined pressure, effectively preventing wrinkles from occurring. Next, the main body of the hose, which has been heated to the softening point, is supplied to the bending machine by pulling the end of the hose further. Then, when the sensor detects the hose body and further detects that the upper and lower molding positions are correct, the upper and lower cylinders are activated, the piston rod is extended, and the upper and lower molds sandwich the hose body from above and below and mold it. The molded hose body is then held by the upper and lower molds, which circulate and move along the loop guide by a chain drive or the like, and is automatically sent to the cooling means while still molded. In the same way, the heated hose body continuously delivered from the heating means is sequentially molded by a plurality of molds circulating and moving along the loop guide. When the cooling means detects the transported hose body by a sensor, it releases cooling water from the outlet provided at the end of the supply pipe to cool the hose body in the molded state. The cooling time should be at least minutes to obtain a sufficiently bent hose body. When the mold is transported to the end of the cooling process, the sensor detects and activates the cylinder, the piston rod contracts, and the mold is divided into upper and lower parts to release and demold the molded hose body. The molds, which have been divided into upper and lower parts, are transferred along the loop guide and the previous process is repeated again, and the demolded and freed hose body is continuously pushed through the guide roller into the stowage means and stowed sequentially. When all of the hose body that has been wound onto the winding drum has been unwound, a sensor located near the winding drum detects the end of the unwinding, and the pressure means, heating device, and bending device are stopped, and the automatic open/close valve is opened to remove the pressure from the hose body. Then, the hose body is removed from the winding drum of the accommodating device, the blind plug is removed, and the hose is cut to a fixed length using a fixed length cutter or the like not shown in the figure according to the required hose length to obtain a formed hose having a predetermined bend shape. In this way, the hose body is already vulcanized, and the pressure is applied inside the inner resin layer even before heating, and the pressure is constantly applied inside the inner resin layer until the demolding process is completed over the entire length of the hose body. At the same time, the upper and lower molds and both circulate to continuously sandwich and mold the hose body. The molded hose body is conveyed to the cooling means in the molded and sandwiched state, so that the hose body can be continuously and automatically molded.

Disadvantage of the <CIT> method and device is in necessity of using pressurized hose during whole process, using external heating for temperature higher than vulcanization temperature of the rubber, while due to external heating, the internal layer is heated only by heat transfer from outer space through both rubber layers to internal layer and the internal cavity of the hose is heated only by this heat transfer. Another disadvantage is necessity of the regulation of the internal pressure in the hose, which is dependent on temperature of the internal cavity of the hose etc. External heating of the hose also negatively affects final parameters of the rubber or gum layers of the hose. The method and device used is complicated and expensive and is usable for enough long hoses, not for short or semi-short pieces.

From <CIT>, <CIT> and <CIT> are known various moulds, in which is formed a longitudinal shaping groove, whose cross-section profile is adapted to receive a heated hose to be spatially shaped, whereby the mould has smaller radii for the individual bends of the hose than the final desired radii of the individual bends of the hose and, at the same time, the mould has greater angles for the individual bends of the hose than the final desired angles of the individual bends of the hose.

The aim of the invention is therefore to eliminate or at least minimize the disadvantages of the background art.

The aim of the invention is by a method of shaping a multi-layer hose composed of an outer layer of vulcanized rubber or gum, and an inner layer of a thermoformable material, and optionally composed of at least one intermediate layer between the outer layer and the inner layer, whose principle consists in that the hose is straight and is shortened to required length, the cavity of the hose is connected to a source of a heating medium and the hose is then internally heated by the passage of the heating medium through the empty cavity of the hose, the heating is performed to the lowest bending softening temperature selected from the bending softening temperatures for the inner layer and intermediate layer, subsequently the hose is disconnected from the source of a heating medium and the hose is inserted into a individual rigid shaping mould, in the rigid shaping mould the hose acquires a spatial arrangement having radii of the individual bends of the hose determined by the rigid shaping mould and angles of the individual bends of the hose determined by the rigid shaping mould, whereupon the hose is tempered by placing the rigid shaping mould with the inserted hose in a tempering chamber for a suitable time and then the hose, still inserted in the rigid shaping mould, is cooled and subsequently the hose is removed from the rigid shaping mould, whereby the hose, after being removed from the rigid shaping mould, the hose due to the action of the outer layer and the inner layer and also the optional intermediate layers changes its spatial arrangement in such a manner that the radii of the individual bends of the hose being determined by the mould increase to the final desired radii of the individual bends of the hose, whereas the angles of the individual bends of the hose being determined by the mould decrease to the final desired angles of the individual bends of the hose.

The principle of the device for performing the method of moulding a multi-layer hoses according to any of claims <NUM> to <NUM> consists in that it comprises a rigid shaping mould, wherein the size of the mould radii for the individual bends of the hose and the size of the mould angles for the individual bends of the hose have values, whereby the decrease of the radii of the mould and the increase of the angles of the mould corresponds to the action of the outer layer and the inner layer and also the optional intermediate layers after removing the multi-layer hose from the mould and the rigid shaping mould is adapted for inserting the hose being previously internally heated by the passage of the heating medium through the empty cavity of the hose and the rigid shaping mould is further adapted for tempering the hose in the mould and for cooling the hose in the mould.

The present invention makes it possible to economically, easily and quickly spatially shape multi-layer hoses with a pre-vulcanized rubber or rubber outer layer, while achieving high quality and precision of the output products. Multi-layer hoses with pre-vulcanized rubber or gum outer layers are readily available since they are the final product of many manufacturers of such hoses and are affordable, whereby the invention eliminates the earlier need for additional vulcanization of the rubber or gum outer layer.

The invention is schematically represented in the drawings, wherein <FIG> shows a cross-section of a two-layer hose, <FIG> shows a cross-section of a three-layer hose, <FIG> is a perspective view of an example of a forming mould - a moulding labyrinth, <FIG> is a plan view of an exemplary embodiment of a part of the mould with a shaped hose, <FIG> is a side view of an exemplary embodiment of a part of a mould with a hose to be shaped of <FIG>, <FIG> is a plan view of the shape of the hose in the mould according to the exemplary embodiment of <FIG>, <FIG> is a plan view of the resulting shape of the shaped part of the hose after removal from the mould according to the embodiment of <FIG>, and <FIG> is a plan view of the shape of the hose in the mould according to the background art.

The invention will be described with reference to an exemplary embodiment of a method of shaping a multi-layer hose comprising a vulcanized outer rubber or gum layer, and a device for performing it. If the word "rubber" or its derived forms is used in the following text, the word "gum" is also included in this meaning, and its derived forms. That means that if hereinafter only the word "gum" or its derived forms appears in the following text, it means automatically the same as the word "rubber" and its corresponding derived forms.

Accordingly, according to <FIG>, it applies that: <MAT> and <MAT>.

The shaping of the multi-layer hose <NUM> according to the present invention is performed in such a manner that a straight multi-layer hose <NUM> with a rubber or gum outer layer <NUM> is used as a "starting semi-finished product", this outer layer <NUM> being fully vulcanized from the initial production of the multi-layer hose 1_. This starting semi-finished product is shortened to the required length. The multi-layer hose <NUM> thus prepared is connected by its empty cavity, i.e. a cavity without a support mandrel, to a source of a heating medium, whereupon the internal heating of the hose <NUM> is started by the passage of the heating medium through the cavity of the hose 1_. The hose <NUM> is internally heated to the softening temperature of the inner layer <NUM> of the hose <NUM> for bending, regardless of the temperature value of the rubber or gum outer layer <NUM> of the hose 1_. If the hose <NUM> has an inner layer <NUM> and also at least one intermediate layer <NUM>, the hose <NUM> is heated internally to the softening temperature of the inner layer <NUM> or the intermediate layer <NUM>, which is the most temperature sensitive layer, i.e. the layer <NUM>, <NUM>, which exhibits the lowest softening temperature for bending. Obviously, the other layers <NUM>, <NUM> and, ultimately, also the outer layer <NUM> are heated to a temperature that does not reach the ideal softening temperature of the respective layer <NUM>, <NUM> for bending. Indeed, if any one of the intermediate layers <NUM> or the inner layer <NUM> were heated to a temperature higher than their softening temperature for bending, that would cause thermal damage to the layer <NUM>, <NUM> and the layer <NUM>, <NUM> would be damaged during the bending of the hose <NUM>, which would lead to deterioration of the quality of the entire bent hose 1_. In principle, it can be therefore summarized that the hose <NUM> is heated internally to the lowest softening temperature for the bending of the inner layer <NUM> or the optional intermediate layers <NUM> depending on the specific material of the inner layer <NUM> and the intermediate layers <NUM>.

Thus, before the actual bending of the hose <NUM> according to the invention, i.e. before starting the internal heating of the hose 1_, the softening temperatures for the bending of the individual layers are determined first from the material composition of the individual layers <NUM>, <NUM> of the hose <NUM> and the lowest bending softening temperature is selected from these temperatures and this lowest bending softening temperature is used as the internal heating temperature of the hose 1_. Current knowledge of the inventors indicates that this lowest softening temperature for the inner layer <NUM> as well as for the intermediate layers <NUM> is always substantially lower than the softening temperature for bending the rubber or gum outer layer <NUM> of the hose <NUM>, so there is no need to include in the selection the lowest temperatures as well as the softening temperature for bending the outer layer <NUM> of the hose <NUM>. However, for the sake of the completeness of the material characteristics of the hose <NUM>, it is advisable to know also this temperature. Under the present conditions, with regard to the material composition of multi-layer hoses for the automotive industry and transportation technology and with regard to economic viability of the manufacturing process, the internal heating time of the hose <NUM> is in the range of <NUM> to <NUM> minutes, preferably in the range of <NUM> to <NUM> minutes, ideally "about" <NUM> minutes, or <NUM> minutes. Furthermore, it appears that for internal heating it is advantageous to use flowing hot air or hot water or hot steam or superheated steam.

As a result of internal heating, the stiffness of the inner layer as well as of that of any intermediate layers <NUM> is reduced <NUM> and the tension on these layers <NUM>, <NUM> from the production of the hose <NUM> with a vulcanized rubber or gum outer layer <NUM> is released, whereupon the internally heated hose <NUM> is disconnected from the heating device and is inserted, manually or mechanically, into the mould F. If necessary, after the hose <NUM> is internally heated and before it is inserted into the rigid shaping mould F, a mechanical support mandrel is inserted into the hose <NUM>, which is either left in the hose <NUM> for the whole period of forming in the mould F or which is removed gradually during subsequent insertion of the hose <NUM> into the mould F.

Subsequently, the hose <NUM> in the mould F is tempered and cooled. The tempering is carried out by placing the mould F with the inserted hose <NUM> in a tempering chamber (not shown), in which the tempering temperature is again maintained depending on whether it is the inner layer <NUM> or the optional intermediate layer <NUM> (or intermediate layers <NUM>) that is more temperature sensitive. Tempering takes place for a suitable time. After tempering, the hose in the mould is cooled, either by leaving it in the air or by applying coolant or cooling air, either on the outer and/or inner surface of the hose <NUM>, because the cavity of the hose <NUM> inserted in the mould F is still accessible for connection to the inlet of the cooling medium. Alternatively, tempering is performed in such a manner that the temperature in the tempering chamber gradually decreases, whereby this gradual decrease in the temperature is slower than the above-mentioned cooling in the air or cooling by air or by a cooling medium. Since the forming mould F is relatively inexpensive, a plurality of identical moulds F are available so that the hoses <NUM> are heated gradually or batchwise. After that they are separately inserted into the individual moulds F, in which they separately cool or are separately cooled. After cooling, the hose <NUM> is removed from the mould F and the mould F returns to the outlet of the hoses <NUM> from the heating device so that a new heated hose <NUM> can be inserted. The hose <NUM>, which has been removed from the mould F, changes its shape determined by the mould F due to the action of the outer layer <NUM> of pre-vulcanized rubber or gum and the inner layer <NUM> and also the optional intermediate layers <NUM> in such a manner that the radii rF of the individual bends of the hose <NUM> which are determined by the mould F increase to the final desired radii rv of the individual bends of the hose <NUM>, whereas the angles αF of the individual bends of the hose <NUM> which are determined by the mould F decrease to the final desired angles αv of the individual bends of the hose 1_. The thus spatially shaped hose <NUM> henceforth retains its altered (deployed) spatial arrangement.

As can be seen in <FIG>, the mould F has therefore the individual radii rF for the individual bends of the hose <NUM> smaller than the final desired radii rv of the individual bends of the hose <NUM> and, at the same time, the mould F has angles αF for the individual bends of the hose <NUM> greater than the final desired angles αv of the individual bends of the hose <NUM>, whereby the decrease of the radii rF for the individual bends of the hose <NUM> and the increase of the angles αF for the individual bends of the hose <NUM> corresponds to the synergistic effect of the outer layer <NUM> of pre-vulcanized rubber or gum and the inner layer <NUM> and the optional intermediate layers <NUM> to the final desired radii rv of the individual bends of the hose <NUM> and the final desired angles αv of the individual bends of the hose <NUM> and to the final shape of the shaped hose 1_. In other words, the decrease of the radii rF for the individual bends of the hose <NUM> and the increase of the angles αF for the individual bends of the hose <NUM> is determined by the synergistic effect of the outer layer <NUM> of pre-vulcanized rubber or gum and the inner layer <NUM> and the optional intermediate layers <NUM> on the final desired radii rv of the individual bends of the hose <NUM> and the final desired angles αv of the individual bends of the hose <NUM> and on the final shape of the shaped hose <NUM>.

Claim 1:
A method of shaping a multi-layer hose (<NUM>) composed of an outer layer (<NUM>) of vulcanized rubber or gum, and an inner layer (<NUM>) of a thermoformable material, and optionally composed of at least one intermediate layer (<NUM>) between the outer layer (<NUM>) and the inner layer (<NUM>), during which the hose (<NUM>) is internally heated, then inserted into a mould (F) in which it is cooled and after that it is removed from the mould and the hose (<NUM>), by its natural deformation, changes its spatial arrangement determined by the mould (F) into the final desired spatial arrangement, wherein the hose (<NUM>) is a straight and is shortened to required length, then cavity of hose (<NUM>) is connected to a source of a heating medium and the hose (<NUM>) is then internally heated by the passage of the heating medium through the empty cavity of the hose (<NUM>), the heating is performed to the lowest softening temperature selected from the softening temperatures for the bending of the inner layer (<NUM>) and the optional intermediate layer (<NUM>), subsequently the cavity of the hose (<NUM>) is disconnected from the source of a heating medium and the hose (<NUM>) is inserted into a individual rigid shaping mould (F), in the rigid shaping mould (F) the hose (<NUM>) is brought into a spatial arrangement with radii (rF) of the individual bends of the hose (<NUM>) determined by the rigid shaping mould (F) and with the angles (αF) of the individual bends of the hose (<NUM>) determined by the rigid shaping mould (F), whereupon the hose (<NUM>) is tempered by placing the rigid shaping mould (F) with the inserted hose (<NUM>) in a tempering chamber for a suitable time and then the hose (<NUM>), still inserted in the rigid shaping mould (F), is cooled and subsequently the hose (<NUM>) is removed from the rigid shaping mould (F), whereby after removal from the rigid shaping mould (F), the hose (<NUM>) due to the action of the outer layer (<NUM>) and the inner layer (<NUM>) and also the optional intermediate layers (<NUM>) changes its spatial arrangement in such a manner that the radii (rF) of the individual bends of the hose (<NUM>) being determined by the mould (F) increase to the final desired radii (rv) of the individual bends of the hose (<NUM>), wherein the angles (αF) of the individual bends of the hose (<NUM>) being determined by the mould (F) decrease to the final desired angles (αV) of the individual bends of the hose (<NUM>).