CS212912B1 - Method of making the protective layer of the product particularly precast tube - Google Patents

Description

The present invention relates to a method for producing a protective layer of a product, in particular a pre-fabricated pipe consisting of a layer of plastic concrete applied to the surface of the protected product.

Large-size pre-manufactured pipes made of concrete, reinforced concrete, prestressing. concrete, asbeet-cement and other materials of known constructions and designs are not resistant to, aggressive liquids and environments have very low durability Ceramic pipes and fittings, which have a greater resistance to aggressive substances, can only be produced up to a certain size Their diameter ; their production is very energy intensive.

Therefore, pipes made of pure plastics or plastics bags are used for the conducting of aggressive liquids, or the life of concrete pipes is extended at least to some extent by coatings and coatings. Pipes made of plastics are not very strong and therefore cannot be used for high environmental pressures and high mechanical stresses, so they cannot be produced in large diameters. Coatings and coatings of concrete pipes are only temporary measures, because the coating layers do not prevent aggressive substances from reaching the concrete for a long time.

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Pre-fabricated concrete pipes are also known which are provided with plastic inserts inside. However, this type of durable pipe has not yet been widely used in practice, since pipes manufactured by prior art processes have a number of serious drawbacks that limit their applicability. One of the major drawbacks is the poor cohesion of the plastic core or liner and the concrete pipe, which leads to cracks in the atypical surface of both materials and the need for post-treatment, especially J post-injection. After application of the plastic concrete layer to the inner surface of the concrete pipe, the exothermic reaction during the hardening of the concrete always caused its shrinkage) and separation from the concrete surface by a continuous flat crack, which then has to be laboriously filled by injection.

The application of a protective layer to the outer surface of a pre-fabricated concrete pipe has not yet succeeded in providing a continuous protection, since during the polymerization longitudinal cracks in the protective layer have always been formed or separated from the concrete layer.

In order to be able to practically utilize pre-fabricated plastic-coated pipes, it was necessary to develop a new process for producing such uncoated pipes; for separating the plastics layer from the base material and creating cracks in the plastics layer and which would not have other drawbacks of the prior art. *

This practical object is achieved by a process for the production of protective coatings according to the invention, which are formed in particular on pre-fabricated concrete pipes, the principle being that the fresh plastic-concrete mixture is gradually applied to the interior or exterior surface of the pre-fabricated pipe in amounts increasing thickness 1 to 10 cm per minute on the surface of the pre-fabricated pipe, and at the same time as the coating is applied, the coating is rolled with a pressure roller to cure the plastics by converting mechanical energy into heat.

According to a particular preferred embodiment of the invention, during the pressure rolling of the deposited layer, the pressure roller is moved and at the same time the preformed oven is rotated, on whose inner or outer surface the plastic concrete layer is applied or stayed precombined and the pressure roller is moved. According to another particular embodiment of the method according to the invention, the pressure cylinder is only pressed against the surface layer of the preformed tube onto which the plastics layer, applied to the attenuator, is applied by centrifugal force caused by the rotation of the preformed tube at a speed dependent on its diameter.

The main benefit of the process for producing a protective layer of pre-fabricated pipes and other products made of plastics is that by gradually applying plastics to the inner or outer wall of the preformed pipe and simultaneously rolling, by converting mechanical energy into thermal energy directly obtains the necessary heat to induce spontaneous polymerization. optionally polycondensation or polyaddition, depending on the type of plastic concrete binder 212 912 used, and on the other hand the formation of a conventional shrink gap between the base material and the plastic concrete is avoided. In addition, upon completion of the application of the plastics skin layer and rolling, the surface of the plastics core or shell is completely finished and no further surface treatment or treatment is required.

The process for the production of the protective layer according to the invention is explained in more detail by way of an exemplary embodiment of this method.

On the reinforced concrete pipe with a diameter of 120 cm it is necessary to apply a protective plastic concrete layer from the inside. In this case, the reinforced concrete tube is left in the form of a rotating production device in which the tube is formed by blasting in a horizontal position. A separating bar is placed in the dried oven, to which a fresh plastic-concrete mixture consisting of a furan binder and a mineral filler with a grain size of up to 2 mm in a weight ratio of 1:10 is fed by means of a dosing device. The oven is rotated at a speed of 200 rpm, while pressing the fresh plastics mixture with a heated roller, inserted just behind the manifold, onto the surface of the concrete oven and during the next application process on the previous plastics layers. The pressure roller has a diameter of 30 cm and is pressed at a pressure of 2.0 MPa. The feed rate of the plastics mix is controlled so that the total thickness of the protective layer of 2 cm is applied over 200 revolutions of the oven, i.e. within about one minute. The total rolling time, including the time of application of the plastics layer, is about 2 min.

In other exemplary processes, the press roller pressures may vary from 0.1 to 3.0 MPa, the relative velocity of the press roller to the wall of the prefabricated tube is from 1 to 20 m / s, the press roller having a diameter greater than 1/6 of the diameter of the concrete pipe and greater than ten times the thickness of the rolled layer.

The protective layer may be applied to the inner surface or to the outer surface of pipes of concrete or other material, and similarly may be applied to the surface of other products having planar surface areas.

L monolithic plastic concrete pipes can be produced in the same way by applying a coating to the inner surface of steel molds.

Claims (6)

SUBJECT OF THE INVENTION Method for producing a protective layer of a product, in particular a pre-fabricated pipe, comprising a layer of plastic concrete applied to the surface of a bent product, characterized in that the fresh plastic concrete mixture is applied successively in partial layers on the surface of the pre-beaded product at a rate and in amounts increasing the thickness layers on the surface of the product to be protected by 1 to 10 cm per minute, wherein at the same time and applying partial layers of the plastics mixture, the coating is rolled by repeated travel of the pressure roller to cure the plastics under pressure by converting mechanical energy into thermal energy. 2. The method according to claim 1, wherein the fresh plastics layer is successively deposited in the sub-layers on the surface of the stationary pre-fabricated oven and the pressure roller is moved behind the applicator and circulates on the layers on the inner or outer surface of the oven. j Method according to claim 1, characterized in that the fresh plastics mixture is successively applied in partial layers to a rotating pre-fabricated pipe and a pressure roller rolls over the rotating surface of the deposited layer. 4. The method of claim 1, wherein the fresh plastics composition is applied by a stationary coating device to a rotating preformed oven and held on the inner walls of the oven by the centrifugal forces exerted by the rotation of the oven, maintaining the pressure roller in a fixed position and the inner surface of the partial protective layers applied. 5. A method according to any one of claims 1 to 4, characterized in that the pressure roller is pressed onto the applied protective layers at a pressure of 0.1 to 3.0 MPa and moves relative to the surface of the protective layer at 1 to 20 m / aec, by curing the concrete, the cylinder can be heated. 6. A method according to any one of claims 1 to 4, wherein the fresh plastics composition is applied to the inner surface of the tubular mold.