DE10331487B3 - Coating longitudinal components, eg plastic pipes, comprises applying a foamable plastic mass, distributing it over the component circumference, moulding and hardening - Google Patents

Abstract

A process for coating longitudinal components (10) made of plastic, especially pipes (11), comprises applying a foamable plastic mass (8), distributing it over the component circumference, and then moulding and hardening it. A supporting gas is directed to the moulding region, and a support gas sleeve is formed. The plastic is applied by spraying from a number of nozzles (16) or a ring nozzle (12). The component surface is treated before the foamable material is applied. The treatment consists of corona discharge or flame treatment. The foamable plastic is a reactive mixture, eg polyurethane, and the support gas is air.

Description

The The present invention relates to a method for coating of elongated objects made of plastic according to the preamble of Claim 1, as well as a molding device for molding a on an elongated Plastic object applied foaming plastic mass according to the preamble of claim 20 and a coating device for coating an elongated Plastic object according to the preamble of claim 36.

It is known extruded plastic pipes or other elongated Plastic articles with an outer layer of foam to provide, for example, to give them insulating properties lend, as they are needed among other things in the construction industry.

Also for the Manufacture of application rolls that absorb liquids, such as Painter's rolls, it is necessary to use tubular elements with a layer of foam to prove that in this case additionally absorbent have to be. usually, this happens through subsequent application an otherwise produced foam layer made of an absorbent plastic material the roller body. The role base body is usually for weight reasons also consist of a plastic that is applied especially by sticking the foam layer.

The continuous production of a tube with an integral foam layer has hitherto been difficult since the foam layer is mostly made of a foaming material, in particular a foaming and then reacting and / or curing plastic material. The material properties of the foam layer are particularly strongly dependent on the ambient conditions during the foaming process, so that uncontrolled parameters can result in a non-uniform foaming or an uneven distribution of the foam cells in the foam material. For this reason it is, for example, from the DE 195 07 110 A1 It is known that when a foaming plastic melt is applied to a continuous plastic inner tube by means of a quill cross-spray head, the propellant-containing melt can continuously emerge from the nozzle gap of the cross-spray head and expand into a cavity that consists of the plastic inner tube, the end face nozzle or mandrel surface of the quill cross-spray head subsequent, half-shell or multi-shell shapes of two or more continuously rotating mold chains is formed. The cavity is delimited in the extrusion direction by the hardening foam. The plastic inner tube moves at the same speed as the mold chains. The mold chains can be provided with a non-stick coating and cooled with air, water or refrigerant. Due to the contact with the mold chains, the expanding and filling the foam forms a closed outer skin. For example, an extruded material such as PE foam or else a fully reacting plastic mixture such as polyurethane is proposed as the foaming plastic material.

On the other hand, it was, for example, from the DE 196 29 678 A1 It is known to encase an inner tube with a plastic film shaped into a tube and to introduce a foaming plastic into the space between the inner tube and the plastic tube, and then to insert the inner tube with the foaming plastic and the tube surrounding it into a molding tool in order to produce a heat-insulating conduit retracting mold halves.

The The methods described have considerable disadvantages in operation on. The moving and possibly tempered mold chains influence the consistency of the finished foam layer, since the reaction or curing takes place in contact with an outer surface. For example, a surface area can form in which the proportion of foam cells is lower than in an inner area the foam layer. In addition, the implementation of a concurrent, heated or cooled Mold chain very much in the production as well as in the production complex, because their control must be precise to the production process be coordinated. additional Costs are particularly due to restrictions on those to be used Materials caused, for example, special non-stick properties must have.

in the In the case of using a moving film to limit the Foam layer to the outside the demands on the moving mold chains decrease, however this process is due to the large amount of film that runs along expensive and also produces large ones Amounts of waste. In terms of the surface quality the same applies to the foam layer as for the other method described, depending on the adhesive properties between the film and the foam layer, however, it can also damage the outside Foam cells come when removing the film.

Attempts to form release films from liquid release agent instead of a film on the mold chain have so far not been successful results.

On Another problem that occurs with moving mold chains is that very difficult adjustment. For example, in the case of Pipe manufacturing very difficult, an even thickness of the foam layer to ensure.

It is therefore the object of the present invention, a method for coating elongated Plastic articles to introduce with a layer of foam that is inexpensive, at the same time one better quality ensures the geometry and the nature of the surface of the foam layer, and an apparatus for performing this method, the is also characterized by few wearing parts and inexpensive is to be realized.

The solution this task is carried out by a coating process according to the features of claim 1 and by a molding device according to the features of claim 20 and a coating device according to the features of claim 36.

Especially The method and the use of the devices according to the invention have been found to be advantageous when using foams proven from reactive mixtures such as polyurethane. Here is the foaming one Plastic mass almost liquid at first, by the following chemical reaction of the individual components of the mixture, below circumstances in cooperation with the physical expansion of an additional buried Propellant, the desired Foam whose cell walls only during the React expansion and become sufficiently stable.

According to the invention Process for coating elongated objects made of plastic and especially of pipes, where a foaming Plastic mass on the elongated and in its longitudinal direction moving plastic object is applied. As a result the plastic mass in the desired Kind about distributed the scope of the plastic object, for example here a layer of foam of the same thickness may be desirable, but certainly other cross-sectional shapes of the foam layer are also conceivable. To during or already of distributing foams the plastic mass reacts when using a mixture reactive components and / or hardens, so that after Passing through a molding area is essentially dimensionally stable.

Around the surface structure the foaming Do not damage the plastic mass and at the same time a targeted shaping of the very beginning to enable unstable plastic mass takes place in the shaping area a directed support gas entry, which also with the foaming Plastic mass interacts to form a supporting gas envelope, which is essentially the outer contour of the Plastic mass specifies and causes the plastic mass during the Passing through the forming area is formed. Through the use according to the invention a supporting gas envelope for the shaping learns the foaming Plastic mass during the molding does not make any contact with surfaces that change their surface structure to damage or could modify. The support gas entry must be done in such a way that the interaction between the expanding plastic mass and the supporting gas flow create a supporting gas envelope, the the desired outer contour of the plastic mass.

Especially the supporting gas flow is preferred with Help one the elongated Plastic object and the foaming plastic mass in the molding area at least partially surrounding boundary along the outer contour the plastic mass channeled. This allows a higher flow rate of the support gas along the outer contour reach the plastic mass, and thus a more effective shaping cause.

moreover the support gas is introduced preferably several times over the curing area, in order to achieve a sufficient support gas flow for the shaping support gas envelope. A first support gas entry is preferred immediately after the foaming Plastic mass realized. The plastic mass is still here most unstable, and must by the targeted entry of the support gas over the circumference of the elongated Plastic object are distributed or held there.

The inventive method comes advantageously immediately after production, usually by means of extrusion, of the object to be coated. The coating according to the present Invention then occurs while passing through the extrusion line before the plastic object is cut to length. The direction of movement of the Plastic object is therefore horizontal in most cases his. But it is also possible to have a vertical guidance of the Plastic object to provide what for the uniform shape the foaming Plastic mass is beneficial, which is otherwise under the influence gravity at a lower area circumference of the elongated Could collect plastic object.

Especially with a non-vertical loading Movement of the elongated plastic object, the supporting gas is therefore preferably introduced asymmetrically in order to counteract the influence of gravity on the applied, foaming plastic mass.

The Applying the foaming Plastic mass is advantageously carried out by feeding the intumescent Plastic mass on the moving plastic object from at least a nozzle. This nozzle can be connected to an extruder that plasticizes the foaming plastic mass, mixed with a physical or chemical blowing agent and to the nozzle promotes, or but also with a mixing head for a reactive mixture consisting essentially of polyol and Polyisocyanate can exist, and a physical or chemical Propellant can be buried.

Especially it is advantageous to the foaming Plastic mass over several spray nozzles spray on the plastic object, as this causes the plastic mass more evenly the surface the object is distributed and better by the pressure when spraying liable.

As well but it is also possible the foaming Plastic mass over one coaxially over to apply the transverse circumference of the nozzle to be coated. This nozzle preferably has the same cross-sectional shape as the one to be coated Object, and surrounds it circumferentially. This procedure offers especially when coating pipes, but here Applying the foaming Plastic mass over a ring nozzle, that surrounds the moving pipe can take place. By such a design Nozzle can the foaming Plastic mass with all peripheral points of the object to be coated come into contact at the same time, and does not have to go through the Scope of the object to be coated can be distributed. Also here it is possible an asymmetrical nozzle shape to be provided so that, for example, on an upper area of the more material to be coated is discharged than to a lower one, so too the influence of gravity counteract.

Especially it is advantageous if the elongated Plastic object before applying the foaming Plastic mass a surface treatment learns since this will cause the adhesion properties between the surface of the Improved plastic object and the plastic mass to be applied become. Therefor are methods known from the prior art, for example a corona treatment or a surface treatment by flaming.

The The present method is particularly suitable for the application of a Coating with a mixture of reactive components, in particular from foamed Polyurethane, as a foaming Plastic mass is in particular a mixture of polyol and Polyisocyanate used with physical or chemical blowing agents was transferred. Since such a reactive mixture at the time of Application still extremely unstable is and almost liquid is present, the shaping by means of the supporting gas envelope according to the invention is here Of particular advantage, since the mass still has no inherent stability and every contact with other, even surrounding surfaces destroy or at least affect would, or the mass would adhere to possibly moving surfaces.

Therefore is called foaming Plastic mass also preferably uses a dixotropic system, that a fast flow and possible dripping of the foaming plastic mass both when applying as well as during of the further molding process.

It is also advantageous to use CO ₂ as a blowing agent for the foaming plastic mass, which, for example in the case of a reactive mixture, leads to the fact that the plastic mass leaves the mixing unit like a cream and is no longer almost liquid, as a result of which it is applied to the moving object molding simplified.

As supporting gas is in the inventive method preferably uses air, which makes the process even cheaper designed. additionally can the support gas can be mixed with a release agent, making a possible Adhere to limiting elements with which the foaming plastic mass in certain circumstances could come into contact is prevented. It is also possible, and for a quick curing the foaming Plastic mass advantageous to temper the support gas and in particular to heat.

After the foamed plastic composition has hardened in the desired shape, forming an intimate connection with the plastic object, the plastic composition is preferably surface-treated. At this point, the foam layer is already so stable that it can be touched safely and pressed, for example. This makes it possible to guide the elongated plastic object together with the foam coating through possibly driven rollers in order to center and transport the product. At the same time, these roles can act as cell openers, for example in the manner of a cracking station. In addition to or instead of this tour, others can Surface treatment steps follow, such as grinding the surface to open the cells, which is advantageous, for example, when the finished product is used in paint application rolls or similar products which must be absorbent. The continuous product is then cut to a desired length.

The The present invention also includes a molding device for molding one on an elongated, in its longitudinal direction moving plastic object applied foaming plastic mass, like you for the implementation of the method presented can be used. This molding device extends essentially over an area where a curing and the molding area corresponds to the applied plastic mass, and has means for forming a support gas envelope, the support gas envelope in cooperation with the foaming Plastic mass whose outer contour pretends.

Especially the means for forming the supporting gas envelope preferably comprise at least a nozzle for introducing and aligning the support gas. advantageously, this is at least one nozzle longitudinal based on the elongated plastic object and / or in the circumferential direction of this object and / or in the radial Direction adjustable so that when production starts an optimal Attack point of the registered support gas set and that Form the support gas envelope in the Production can be further optimized. Particularly advantageous it is here if several such nozzles are provided, which in the Interaction with the foaming Plastic mass bring about a shape of this.

As It has proven particularly advantageous to have at least one coaxial nozzle to the elongated Form plastic object, which nozzle is essentially a outer contour the die gap shape specifying the plastic mass having. The inside diameter of the nozzle is slightly larger than the outside diameter the foaming plastic mass in the area where the nozzle is located is. This configuration of the nozzle enables the support gas to be introduced done particularly effectively, and it forms a support gas envelope in the Form from that of the desired outer contour the foaming Plastic mass corresponds. Especially in the case of a pipe that should be surrounded with a concentric layer of foam this with an annular nozzle easy to implement.

It can be particularly advantageous, a combination of several different types of nozzles can be used, for example, a ring nozzle together can be used with several separately adjustable individual nozzles. In any case it has proven to be advantageous to design each nozzle to be separately controllable, as a result, the formation of the most effective, shaping support gas envelope possible from the foaming Plastic mass and also during of the manufacturing process can be optimized.

How already mentioned in the description of the method, the elongated Plastic object often not moved vertically, so that on the deployed, foaming Gravity attacking plastic mass an uneven distribution this about causes the scope of the plastic object. For this reason it is beneficial to use the nozzles perpendicular to the longitudinal axis arrange the plastic object asymmetrically, or in the case of coaxial nozzles to be designed asymmetrically so that the supporting gas envelope counteracts gravity.

According to one particularly preferred embodiment The present invention provides limiting means which so about the elongated Plastic object together with the surrounding plastic mass are attached that between the outer contour of the plastic mass and a flow space for the supporting gas envelope is formed for the limiting means. By the attachment of these limiting means can preferably be introduced via nozzles supporting gas particularly well along the outer contour the foaming Plastic mass can be channeled, and already a lower support gas entry is sufficient to form a relatively high flow velocity at the Surface of the Plastic mass.

This Limiting agents preferably essentially comprise at least one hollow profile Area that over its longitudinal extension is coaxial with the plastic object. In particular, the hollow profile-shaped area also forms tubular be what the coating of plastic pipes will be the norm. These limiting means can For example, consist of several segments that form one in essential dense coat can be put together. In any case, must be guaranteed that the distance between the elongated plastic object and the limiting means is always greater than that in the respective Area developing foam layer so that it can be avoided touching it between the foaming Plastic mass and the limiting agents comes.

According to a particularly preferred embodiment, the limiting means comprise a plurality of essentially hollow-profile and in particular tubular regions, which are then arranged over the curing region of the plastic compound are, and their cross-section in relation to the direction of movement of the plastic object either remains the same and / or increases, so that preferably only a narrow flow channel for the supporting gas remains between the hollow profile-shaped areas and the foaming plastic mass.

In In any case, it is advantageous if the at least one, essentially shaped hollow profile Area about its scope and / or over its length nozzle means for forming and maintaining the support gas envelope. When using several limiting means, which are arranged one behind the other advantageously between the substantially hollow profile-shaped areas additional nozzle means provided to form the support gas envelope. This can for example as coaxial nozzles, in the case of a pipe to be coated, preferably designed as ring nozzles be, or from several possibly asymmetrical over the Extent of elongated Distributed plastic nozzles exist. Generally is it is also advantageous here if the nozzles can be controlled individually.

Around the curing time the foaming mass to influence, it has proven to be advantageous to limit the means to be temperature-controlled at least in some areas. In addition or as an alternative, funds can be provided to the support gas to temper.

The Limiting means are particularly preferably made of steel, plastic or other suitable material.

As supporting gas air is advantageously used, which means that a separate supporting gas does not apply and only minimal protective measures must be provided. At the curing time the foaming To influence plastic mass, the support gas can be tempered additionally.

Furthermore, it has proven to be advantageous to provide means to that supporting gas with an additional Releasing release agent, which makes even in the unwanted Case of touching sticking of the plastic mass between the foam jacket and the limiting means on the limiting means is largely avoided.

The The present invention further relates to a coating device for coating an elongated, longitudinal moving plastic object and in particular a tube with one foaming Plastic mass, such as in an extrusion line directly after the creation of the elongated moving plastic object or in a separate coating station on previously finished plastic objects Use can come. Such a coating device comprises an application device for applying the foaming Plastic mass on the elongated Plastic object, and a molding device by means of which the applied foaming Plastic mass possibly over distributed the circumference of the plastic object into a desired shape brought and then molded in this. Such a molding device has already been described and follows in the direction of movement of the plastic object essentially directly on the applicator.

A Application device used in such a coating device a feeder for the foaming Plastic mass, by means of which the foaming plastic mass of a manufacturing site, for example an extruder or a Mixing head, close the outer circumference of the elongated plastic object guided can be.

preferably, includes this feed device at least one nozzle over which the foaming Plastic mass is discharged onto the plastic object, whereby however, it is advantageous if the feed device has a plurality of nozzles, the above the circumference of the elongated plastic object are arranged so that a desired amount in each circumferential area on foaming Plastic mass are discharged onto the plastic object can. The arrangement of the nozzles depends on which one outer contour should accept the foam layer to be formed on the plastic object. If any additional personnel cause the plastic mass to not evenly or not as requested on the surface distributed of the plastic object, the arrangement of the nozzles can accordingly be adjusted. For example, this can essentially be the case horizontal movement of the elongated Plastic object under the influence of gravity, in In this case you will see more plastic mass in the upper area apply than in its lower area. Here it can if necessary also be sufficient, just a single nozzle above the plastic object to provide the discharged plastic mass then using the Gravity and a suitably designed support gas envelope over the entire surface to distribute the plastic object.

In particular in the case of relatively liquid foaming plastic masses at the beginning, it has proven to be advantageous to design at least one nozzle of the feed device as a spray nozzle, since the surface of the plastic object can be wetted particularly effectively, and especially sere adhesive properties between plastic object and applied plastic mass. Even if spray nozzles are used, it is advantageous to arrange them over the circumference of the plastic object, since this enables a better wetting of the entire surface.

As a general rule is it also possible to design the application device in such a way that redundant nozzles are provided are, so in the case of maintenance or repair of some nozzles the redundant nozzles can be used in their place and therefore none at all Production loss comes.

According to one another particularly advantageous embodiment of the present Invention is the at least one nozzle of the feed device as to the elongate Plastic object coaxial and essentially its cross-sectional shape replica nozzle educated. So this nozzle points a free internal cross-sectional area on that is slightly larger and the shape is the same as the outer cross section of the elongated moving plastic object so that it can easily pass through the nozzle can. The nozzle gap adjoining the inner cross-sectional area of the nozzle forms with its inner edge follows the contour of the plastic object, its outer edge has essentially a shape of the desired contour of the trainees Foam layer corresponds, but possibly on another Size scale. additionally Is it possible, such a nozzle form such that an asymmetrical plastic mass discharge takes place, for example, to counteract gravity. This Type of nozzle design has proven to be particularly beneficial when it comes to a Plastic object with an essentially circular cross-section, that is to say a pipe acts as ring nozzles or slightly eccentric ring nozzles for asymmetrical Plastic mass discharge are relatively easy to manufacture.

The Dosage of the plastic mass, namely the per unit length amount of plastic mass discharged from the plastic object, must be set so that after the foaming process desirable Foam layer thickness is reached.

Especially Cheap has the coating device according to the invention especially proven when the feeder has a mixing head for a reactive foaming and hardening to plastic Mixture is connected, as is generally from the reaction casting is known. In such a mixing head, reactive components, especially polyol and polyisocyanate intimately mixed, and a blowing agent added. This blowing agent can be a chemical or act as a physical blowing agent.

As a general rule it is advantageous if the application device and the molding device a coating device according to the invention are integrally formed, so when the order of the foaming Plastic mass and the subsequent molding of the foaming water Plastic mass within a single structural unit can. In this case, a nozzle center device is preferably provided, which is both the at least one nozzle the feeder as well as the at least one nozzle of the molding device. For example, it is possible to do this Nozzle means device Form such that they are two essentially concentric nozzles, especially ring nozzles has, the inner of which is the application of the foaming Plastic mass is used on the plastic object while using the outer the Support gas envelope formed becomes.

in the Case of integral formation of the coating device it has proven to be particularly advantageous if the limiting means the molding device substantially sealing against the nozzle center device connect, because it is possible within the space between the restriction means and the nozzle means device build up a dynamic pressure, which is then limited by the limiting means and the foaming Plastic mass along the direction of movement of the moving plastic object channeled as support gas flow , and can thus have a particularly effective shaping effect. in this connection can further nozzle devices be provided to keep the support gas envelope upright to obtain.

Some exemplary embodiments the coating device according to the present invention are described in more detail with reference to the following figures. Show it:

1 a first embodiment of a coating device according to the invention with plastic object to be coated schematically in longitudinal section,

2 a second embodiment of the coating device according to the invention schematically in longitudinal section,

3 a further embodiment of the coating device according to the invention schematically in longitudinal section, and

4 a further alternative embodiment of the coating device according to the invention schematically in longitudinal section.

In 1 is a coating device 1 shown in longitudinal section. This coating device 1 includes a separate application device 2 and a molding device 30 , A, according to the 1 left to right longitudinally moving plastic object 10 first passes through a surface treatment device 20 before using the coating device 1 passes. The application device 2 the coating device 1 comprises a feed device 4 for a foaming plastic mass 8th , and especially for a reactive foaming mixture. The applied foaming plastic mass 8th foams as it passes through a molding area, increases in circumference and finally forms a molded and hardened foam layer 9 , The feeder 4 carries the foaming plastic mass 8th in the case of the horizontal movement of the elongated plastic object shown in the figure 10 The plastic mass is distributed over the entire circumference of the plastic object from above onto it and under the influence of gravity 10 ,

As part of the molding device 30 separately arranged support gas nozzles 36 that are both in the longitudinal direction and over the circumference of the moving plastic object 10 are distributed in interaction with the foaming plastic mass under the influence of gravity 8th a first distribution of the plastic mass 8th about the plastic object 10 and thus a first design. Following the first support gas nozzles 36 are means of limitation 32 provided the the plastic object 10 with the foaming plastic mass adhering to it 8th surrounded in such a way that between them and foaming plastic mass 8th or essentially finished foam layer 9 can form a support gas envelope, the final shape of the foam layer 9 causes. To the already through the support gas nozzles 36 generated support gas envelope in the area of the limiting means 32 must be effectively maintained at the beginning of the limitation means 32 further nozzles, for example in the form of an annular nozzle 38 provided for support gas entry. Such nozzles can optionally extend over the length of the limiting means 32 to repeat. When exiting the with a layer of foam 9 coated plastic object 10 from the molding device 30 has the foam layer 9 sufficient stability to undergo post-treatment steps.

at In the description of the further figures, the same reference numerals are used for components with the same functionality used.

In the 2 is an alternative embodiment of the coating device according to the invention 1 shown in longitudinal section. The plastic object to be coated again runs through 10 the coating device 1 left to right after using a surface treatment device 20 happened. The application device 2 includes a variety of spray nozzles 16 that about the scope of the plastic object 10 are arranged distributed, and with which the foaming plastic mass 8th on the surface of the object 10 is sprayed on. Immediately after the application device 2 follows the molding device 30 , This includes limiting means 32 and 34 which are essentially concentric with the object to be coated 10 are arranged and in some areas with heating means 46 are provided, the faster reaction and curing of the foam layer 9 serve. In the area of limiting resources 32 are about the length, the circumference and also radially with respect to their distance from the plastic object 10 adjustable nozzle means 44 provided for the support gas supply, as indicated by arrows. By means of the nozzle means 44 becomes a supporting gas envelope for shaping the applied foaming plastic mass 8th educated. In order to achieve particularly favorable flow conditions for the supporting gas envelope, the limiting means have 32 a smaller diameter than the limiting means following in the forming direction 34 , However, it is always guaranteed that between the foaming mass 8th and the limiting means 32 a thin cushion of support gas remains. Likewise, the diameter of the limiting means 32 also increase in the form direction. Following the limiting means 32 are means of limitation 34 provided that have a slightly larger diameter. This corresponds to a final diameter of the coated article including the cushion formed by the supporting gas envelope. At the transition between the means of limitation 32 and 34 further nozzle means are provided to maintain the support gas envelope, for example in the form of an annular nozzle 42 , Also in the area of limiting agents 34 can be provided further nozzle means, not shown, for maintaining and shaping the supporting gas envelope. The number of areas with delimiters 32 . 34 the length of the curing area is not limited to two.

In the 3 is a further alternative embodiment of the coating device according to the invention 1 shown in longitudinal section, this time a pipe running horizontally from left to right 11 is coated. Before entering the coating device 1 the pipe passes through a surface treatment device again 20 , for example a flame device. The coating device 1 is integrally formed in the present case and has a nozzle center device 6 a component that is both a feeder 4 for the foaming plastic mass 8th around holds, as well as nozzle means 38 and 40 , which serve to form the shaping support gas envelope. The feeder 4 in this embodiment consists of only a single nozzle 14 which is the foaming plastic mass 8th on the pipe 11 discharges. This is distributed over the circumference of the pipe under the influence of gravity 11 , By using several nozzle means 38 and 40 is from across a lower area of the component 6 distributed multiple nozzles 40 counteracts the influence of gravity particularly effectively with the aid of the supporting gas flow, or effectively incorporates it into the shaping, while it is flowing through the ring nozzle 38 essentially a uniform support gas envelope is formed.

In the embodiment according to 3 are the limiting means 32 . 34 essentially sealing against the integral component 6 performed; so that in the area between this and the limiting means 32 . 34 builds up a dynamic pressure due to the essentially closed system. A lower support gas input is sufficient to form an effective and sufficient support gas envelope. As in the detail in the upper part of the 3 shown, the limiting means 32 . 34 , which are designed, for example, as plastic or metal pipes, can be composed of several areas, between which further nozzle means 42 are provided. This was more precisely already in the case of the embodiment according to 2 portrayed. It is also possible to provide additional nozzle means that extend over the length and circumference of the limiting means 32 . 34 distributed and can be controlled separately.

The length of the limiting means 32 . 34 is essentially determined by a throughput time, which is the foaming plastic mass 8th needed to form a molded foam layer 9 to react or harden, and essentially corresponds to a molding area. When leaving the molding device 30 must the foam layer 9 have sufficient surface stability so that they can come into contact with other objects without being damaged.

The length of the molding device 30 is both from the composition of the foaming plastic mass 8th , the amount applied and the speed of the pipe 10 dependent. As in 3 only in the lower area of the limitation means 32 . 34 shown, but not limited to this range, it is possible to use additional temperature control 46 to provide the reaction or curing time of the foam layer 9 to influence. Usually these will be heaters.

In 4 A further alternative embodiment of the coating device according to the present invention is shown in longitudinal section, in the application 2 and molding device 30 are integrally formed. After passing through a surface treatment device 20 becomes a pipe 11 through one essentially as a ring nozzle 12 trained area of the application device 2 guided. From this the foaming plastic mass 8th about the circumference of the pipe 11 distributed. Here, the ring nozzle can be designed asymmetrically, so that in an upper area more foaming plastic mass 8th is carried out as in a lower area so as to compensate for the influence of gravity. Integrally formed with the application device 2 are multiple nozzles 40 provided over the circumference of the ring nozzle 12 distributed and can be controlled separately. A further ring nozzle can also be used here, which may be designed asymmetrically in order to generate a stronger flow of the supporting gas in a lower region and thus the effect of gravity on the foaming plastic mass 8th counteract. The limiting means 32 and 34 the molding device 30 , and other nozzle means that serve to maintain the support gas envelope over the length of a Ausformbe range are formed analogously to the embodiments already described.

A coating device according to the invention 1 or their components, an application device 2 or a molding device 30 are operated as follows. An elongated plastic object to be coated 10 , especially a pipe 11 , is moved along its longitudinal direction, and preferably undergoes a surface treatment, which results in better adhesion between the surface of the plastic article 10 and the plastic mass to be applied 8th comes. Then one or more nozzles 4 . 12 . 14 . 16 the foaming plastic mass 8th on the surface of the plastic object 10 applied and brought to liability there at least in some areas. Here, the foaming plastic mass 8th both flow onto the pipe surface as well as sprayed onto it or otherwise applied under pressure. Immediately after this, for an optimal distribution of the foaming plastic mass 8th about the circumference of the moving plastic object 10 be taken care of. This distribution can also not be symmetrical to the longitudinal axis of the elongated plastic object 10 respectively. For example, in certain areas of the installation it can be advantageous to use pipes that are more insulated on one side, in which the foam layer is thicker on one side of the pipe.

With the help of support gas nozzles 36 . 38 . 40 . 42 . 44 is in cooperation with the expanding Plastic compound 8th a supporting gas envelope is constructed, which is formed like a tube around it and has a shaping effect. Over the length of a curing or curing area, over which the molding device essentially extends 30 extends, the nozzle means mentioned can be used several times and in any combination in order to provide a supporting gas envelope with the corresponding shaping effect. By following the application device 2 provided limiting means 32 . 34 the molding device 30 such a support gas envelope is formed even more effectively. The plastic mass foams as it passes through the molding area 8th and takes on the desired shape with an outer contour predetermined by the supporting gas envelope. After exiting the molding device 30 is the foam layer 9 sufficiently stable and the coated plastic object 10 can be processed further.

Following the coating device 1 For example, as in conventional extrusion lines, take-off devices can be provided that allow the system to move continuously from the plastic object 10 and applied foam layer 9 ensure and at the same time ensure that the elongated plastic object 10 during the passage through the coating device 1 is centered. Devices for surface treatment of the foam layer can also be used, for example 10 be provided, which serve, for example, to open cells close to the surface, such as a cracking station or a grinding station.

The method for coating elongated plastic articles according to the present invention, and a coating device 1 with application device 2 and molding device 30 By means of which this method can be carried out, there are many advantages. It is thus possible to coat plastic objects with a foaming plastic mass without the structure of the resulting plastic foam being destroyed by contact with possible external limits.

in the Comparison to this coating process is the known alternative with moving, shaping outer walls very expensive and inflexible. So must already when the desired Cross-sectional shape or the diameter of these outer walls can be specially adapted. The also known method, a film as a release agent between Foam layer and outer border carry, is also very expensive and causes a lot of waste. Besides, will the surface of the Foam layer damaged or at least changed by the use of the film.

All these disadvantages are overcome by the use of the coating device according to the invention avoided from the molding device and application device, since the very much easier and cheaper as well as more flexible use of a very thin, shaping Support gas envelope in place a moving film or moving outer walls occurs.

1

coater

2

applicator

4

feeder

6

Nozzle means device

8th

foaming plastic mass

9

foam layer

10

Plastic object

11

pipe

12

ring nozzle

14

single nozzle

16

spray nozzles

20

A surface treatment device

30

molding machine

32 34

limiting means

36

Stützgasdüse

38

ring nozzle

40

multiple nozzle

42

ring nozzle

44

adjustable nozzle means

46

heating

Claims (47)

Process for coating elongated objects ( 10 ) made of plastic, especially pipes ( 11 ), comprising the application of foaming plastic mass ( 8th ) on the elongated plastic object moving in its longitudinal direction ( 10 ), distributing the mass ( 8th ) about the scope of the plastic object ( 10 ) in the desired type and the shaping and hardening of the mass ( 8th ) while passing through a molding area, characterized in that a directed support gas entry takes place in the molding area, whereby in cooperation with the foaming plastic mass ( 8th ) a support gas envelope is formed, which essentially the outer contour of the plastic mass ( 8th ) and through which the foaming plastic mass ( 8th ) is at least partially molded during the passage through the molding area. A method for coating according to claim 1, characterized in that the supporting gas entry using an elongated plastic object ( 10 ) and the foaming plastic mass ( 8th ) at least partially surrounding boundary in the molding area ( 32 . 34 ) along the outer contour of the plastic mass ( 8th ) is channeled. Coating method according to claim 1 or 2, characterized in that the support gas entry several times over the curing area he follows. Coating method according to one of claims 1-3, characterized in that at least one supporting gas entry directly after the application of the foaming plastic mass ( 8th ) he follows. Coating method according to one of claims 1-4, characterized in that the supporting gas entry in particular when the elongated plastic object is not moved vertically ( 10 ) is done asymmetrically. Coating method according to one of claims 1-5, characterized in that the application of the foaming plastic mass ( 8th ) by feeding the mass ( 8th ) on the plastic object ( 10 ) from at least one nozzle ( 12 . 14 . 16 ) he follows. Coating method according to claim 6, characterized in that the application of the foaming plastic mass ( 8th ) by spraying on the plastic object ( 10 ) from several spray nozzles ( 16 ) he follows. Coating method according to claim 6, characterized in that the application of the foaming plastic mass ( 8th ) over a coaxially over the transverse circumference of the object to be coated ( 10 ) extending nozzle ( 12 ) he follows. Coating method according to claim 8, characterized in that the application via an annular nozzle ( 12 ) he follows. Coating method according to one of claims 1-9, characterized in that the elongated plastic object ( 10 ) before applying the foaming plastic mass ( 8th ) undergoes a surface treatment in order to determine the adhesive properties between the surface and the foaming plastic compound to be applied ( 8th ) to improve. A method of coating according to claim 10, characterized characterized that a corona treatment is carried out. A method of coating according to claim 10, characterized characterized that the surface treatment by flame. Coating method according to one of claims 1-12, characterized in that as the foaming plastic mass ( 8th ) essentially a reactive mixture, in particular polyurethane is used. Coating method according to one of Claims 1-13, characterized in that the foaming plastic mass ( 8th ) a thixotropic system is used. Coating method according to one of claims 1-14, characterized in that as a blowing agent for the foaming plastic mass ( 8th ) CO ₂ is used. Coating method according to any one of claims 1-15, characterized characterized that as support gas Air is used. Coating method according to any one of claims 1-16, characterized characterized that the support gas with a release agent. A method of coating according to any one of claims 1-17, characterized characterized that the support gas is tempered and in particular heated. Coating method according to one of Claims 1-17, characterized in that after the foamed plastic mass has hardened ( 8th ) a surface treatment of the plastic mass ( 8th ) he follows. Molding device for molding an elongated plastic object that is moved in its longitudinal direction ( 10 ) applied foaming plastic mass ( 8th ), the molding device ( 30 ) extends essentially over an area which corresponds to a hardening area of the applied plastic mass ( 8th ), characterized in that means are provided for forming a supporting gas envelope which, in cooperation with the foaming plastic mass ( 8th ) whose outer contour specifies. Molding device according to claim 20, characterized in that the means for forming the supporting gas envelope at least one nozzle ( 36 . 38 . 40 . 42 . 44 ) for the support gas. Molding device according to claim 21, characterized in that at least one nozzle ( 36 . 44 ) in the longitudinal and / or in the circumferential direction and / or in the radial direction in relation to the longitudinal axis of the elongated plastic object ( 10 ) is adjustable. Molding device according to claim 21 or 22, characterized in that at least one nozzle ( 38 . 42 ) to the elongated plastic object ( 10 ) is coaxial and essentially the outer contour of the plastic mass ( 8th ) has a predetermined nozzle gap shape. Molding device according to claim 23, characterized in that at least one nozzle ( 38 . 42 ) is an annular nozzle. Molding device according to one of claims 20-24, characterized in that each nozzle ( 36 . 38 . 40 . 42 . 44 ) is separately controllable. Molding device according to one of claims 20-25, characterized in that the nozzles ( 36 . 38 . 40 . 42 . 44 ) perpendicular to the longitudinal axis of the plastic object ( 10 ) are arranged or designed asymmetrically so that the plastic mass ( 8th ) counteracting gravity. Molding device according to one of claims 20-26, characterized in that limiting means ( 32 . 34 ) are provided, which are placed around the elongated plastic object ( 10 ) with plastic mass ( 8th ) are attached that between the outer contour of the plastic mass ( 8th ) and the limiting means ( 32 . 34 ) a flow space is formed for the supporting gas envelope. Molding device according to claim 27, characterized in that the limiting means ( 32 . 34 ) comprise at least one essentially hollow-profile and in particular tubular area, which extends coaxially with the plastic object over its longitudinal extent ( 10 ) is. Molding device according to claim 28, characterized in that the limiting means ( 32 . 34 ) comprise a plurality of substantially hollow-profile and in particular tubular areas, the cross section of which with reference to the direction of movement of the plastic object ( 10 ) remains the same and / or increases. Molding device according to claim 28 or 29, characterized in that the at least one substantially hollow profile-shaped region ( 32 . 34 ) over its circumference and / or length nozzle means ( 42 . 44 ) to maintain the support gas envelope. Molding device according to claim 30, characterized in that between the plurality of substantially hollow-profile regions ( 32 . 34 ) additional nozzle means ( 42 . 44 ) are provided to maintain the support gas envelope. Molding device according to one of claims 27-31, characterized in that the limiting means ( 32 . 34 ) are designed to be temperable at least in some areas. Molding device according to one of claims 20-32, characterized characterized in that means are provided to the support gas temper. Molding device according to one of claims 20-33, characterized characterized in that means are provided for using the support gas to release a release agent. Shaping device according to one of claims 20-34, characterized characterized that air as a support gas is provided. Coating device for coating an elongated, longitudinally moving plastic object ( 10 ), especially a pipe ( 11 ), with a foaming plastic mass ( 8th ), with an application device ( 2 ) to apply the foaming plastic mass ( 8th ) on the plastic object ( 10 ), characterized in that a molding device ( 30 ) is provided according to one of claims 20-35, which in the direction of movement of the plastic object ( 10 ) on the application device ( 2 ) follows. Coating device according to claim 36, characterized in that the application device ( 2 ) a feeding device ( 4 ) for the foaming plastic mass ( 8th ) which is close to the outer periphery of the elongated plastic article ( 10 ) is arranged. Coating device according to claim 37, characterized in that the feed device ( 4 ) at least one nozzle ( 12 . 14 . 16 ) includes. Coating device according to claim 38, characterized in that the feed device ( 4 ) several nozzles ( 16 ) which extends over the circumference of the elongated plastic object ( 10 ) are arranged. Coating device according to claim 38 or 39, characterized in that the at least one nozzle of the feed device ( 4 ) as a spray nozzle ( 16 ) is trained. Coating device according to claim 38, characterized in that the nozzle of the feed device ( 4 ) than to the elongated plastic object ( 10 ) coaxial nozzle that essentially reproduces its cross-sectional shape ( 12 ) is trained. Coating device according to claim 41, characterized in that the nozzle of the feed device ( 4 ) as a ring nozzle ( 12 ) is trained. Coating device according to one of claims 38-42, characterized in that the at least one nozzle of the feed device ( 4 ) is arranged or designed such that the foaming plastic mass ( 8th ) asymmetrical with respect to the circumference of the elongated plastic objects ( 10 ) is applied to this in order to compensate for the influence of gravity. Coating device according to one of claims 37-43, characterized in that the feed device ( 4 ) is connected to a mixing head for a reactive, foaming and plastic-curing mixture. Coating device according to one of claims 37-43, characterized in that the application device ( 2 ) and the molding device ( 30 ) are integrally formed. Coating device according to claim 45, characterized in that a nozzle means ( 6 ) is provided which both the at least one nozzle ( 12 . 14 ) of the feed device ( 4 ) as well as the at least one nozzle ( 38 . 40 ) the molding device ( 30 ) includes. Coating device according to claim 46, characterized in that the nozzle means ( 6 ) essentially two concentric ring nozzles ( 12 . 40 ), of which the inner one of the application of the foaming plastic mass ( 8th ) on the plastic object ( 10 ) serves and the outer one to form the supporting gas envelope.