APPARATUS AND METHOD FOR PRODUCING TUBES.

Abstract

The invention incorporates an apparatus (20) for producing resin tubes, the apparatus (20) having a hollow support structure (4), in which an endless conveyor strip (8) can be wound around the outside of the support structure (4) in a plurality of adjacent windings to form a mold. Figure 1.

Description

APPARATUS AND METHOD FOR PRODUCING TUBES The invention incorporates equipment for extruding and / or winding resin, thermoplastic, or thermosetting tubes or pipes of infinite lengths. The equipment comprises a support structure, such as a hollow-core tube open at both ends, around which an endless belt carrying the plastic tube is fed. The belt follows a helical path so that the belt coils are closely spaced, and after reaching the end of the core tube, the belt is fed into the hollow interior and redirected at the inner end to begin the helical path again. The invention further incorporates a process for extruding and / or winding the plastic tube within the equipment. In a continuous filament winding (CFW) process, the mold consists of plates mounted on a central rotating shaft. A steel strip is wound over the plates to form the outer surface onto which the materials that make up the thermosetting glass polymer (GRP) pipe laminate are applied and cured. Reinforcement is possible using materials such as glass, carbon, or basalt. The point at which the steel strip exits the pipe mold, enters the hollow rotating mold to return to the beginning of the cylinder, and then re-enters to reform the mold surface is a critical process.The stability of the so-called return head (the device that allows the steel strip to come out and be redirected into the hollow cylinder) is fundamental to the quality of the pipe, and an efficient continuous process with mold integrity has resulted in a rigid and stationary return head, with solid steel rods to support the steel strip, hold the rolling, and redirect the steel strip. An apparatus of this type is known from document US 3,979,250. Therefore, the object of the present invention is to provide an improved apparatus and an improved method for producing tubes of resin material. The present object is achieved using the features of the independent claims. Advantageous developments of the invention are specified in the dependent claims. All combinations of at least two features specified in the description, the claims, and / or the drawings are also included within the scope of the invention. When given Lnoznn / zznz / e / YiAi ranges of values, values ​​that fall within the aforementioned limits should also be considered as disclosed limit values ​​and may be claimed in any desired combination. According to the invention, an apparatus is provided for producing tubes of resin material, the apparatus having a hollow support structure in which an endless conveyor strip can be wound around the outside of the support structure in a plurality of adjacent windings to form a mold, the apparatus comprising application means for applying a resin material to the outside of the mold, the apparatus further comprising a return head for supporting the conveyor strip after it leaves the support structure and for feeding the conveyor strip into the interior of the support structure, wherein the return head comprises elements of variable length for supporting the conveyor strip. As a further object of the invention, the invention relates to a method for producing resin tubes, wherein an endless conveyor strip is wound around the outside of a hollow support structure in a plurality of adjacent windings to form a mold, wherein a resin material is applied to the outside of the mold, wherein a return head supports the conveyor strip after it leaves the support structure and feeds the conveyor strip into the interior of the support structure, wherein the return head comprises elements of variable length for supporting the conveyor strip. As an advantage of the invention, the return head can be adapted to the radial position of the conveyor strip and thus provides optimal support of the conveyor strip when it exits the support structure and is fed into the interior of the support structure. As additional advantages, the invention provides higher quality and better long-lasting tube characteristics, a longer conveyor belt life due to less fatigue on return, reduced conveyor belt overlap, and higher production speed. The characteristic resin also comprises thermoplastic and / or thermosetting material. In a preferred embodiment, the variable-length elements comprise pressure elements for pressing the conveyor strip radially towards Lnoznn / zznz / e / YiAi out. As an advantage, the conveyor strip is pressed against the resin material and can maintain the tension and position of the conveyor strip. Next, radial or radially means the perpendicular direction relative to a longitudinal axis extending through the interior of the support structure. According to another advantageous preferred embodiment, the variable-length elements comprise adjustable-length support rods. As an advantage, the support rods are optimally adapted to the position of the conveyor belt. According to another advantageous preferred embodiment, the variable-length elements comprise conveyor belt supports, preferably rollers, mounted on the radial outer ends of movable pistons. As an advantage, the belt supports provide optimal force transmission to the conveyor belt. According to another advantageous preferred embodiment, by way of example, the variable-length elements can move in radial directions, especially between the inner and outer positions. As an advantage, the conveyor belt can be optimally supported in the radial direction. According to another advantageous preferred embodiment, by way of example, the variable-length elements can be moved on cylinders fixed to a return head disk that extends perpendicular to a longitudinal axis of the support structure. As an advantage, the variable-length elements are optimally arranged and can move radially. According to another advantageous preferred embodiment, the variable-length elements vary between preselected maximum and minimum distances depending on the radial distance between the conveyor belt and the longitudinal axis of the support structure. As an advantage, the conveyor belt can be optimally supported at any distance from the longitudinal axis. According to another advantageous preferred embodiment, by way of example, the variable-length elements exert forces on the conveyor belt against the resin material and maintain the tension and position of the conveyor belt. As an advantage, the conveyor belt can be maintained in an optimal position. According to another advantageous preferred embodiment by way of example, the variable-length elements comprise pneumatic actuators, Lnoznn / zznz / e / YiAi elastic, hydraulic, magnetic and / or mechanical. According to another advantageous preferred embodiment by way of example, the apparatus comprises a motor with a motor housing and a cam plate equipped with conveyor strip drives to ensure that the conveyor strip is guided over the mold and that the incoming conveyor strip is firmly pushed over the previous conveyor strip in the mold. According to another advantageous preferred embodiment, the application of resin material is controlled with respect to kg / min and / or the surface area passing under a material application zone to ensure that the correct quantities (kg / cm³) are applied to the mold. This ensures that the material feed is more dynamic and controlled with respect to mold rotation, circumferential speed, and longitudinal tube production speed. According to another advantageous preferred embodiment, by way of example, the sawing of the resin tubes is synchronized with respect to the mold geometry and the longitudinal production speed of the tube. Preferably, the saw allows for two-axis movement, which is a movement toward the surface of the tube at a variable distance between a rotating saw blade and the outside of the tube, and in the direction of tube production as the tube lengthens with each rotation during the sawing process. According to another advantageous preferred embodiment by way of example, there is a dynamic placement of the material application zone with respect to a constant height above the rotating tube surface and a movement of the external heat source with respect to the rotating tube surface to ensure a constant distance from the external heat source to the conveyor belt and / or the outside of the tube. During use of the apparatus, tubular resin articles, such as pipes, can be formed in various ways, for example, by winding fibrous reinforcements of a moving conveyor belt (e.g., fiberglass) impregnated with a thermosetting liquid resin material. The resulting tubular article is then solidified, for example, by placing a portion of the helical path of the conveyor belt in an oven. Alternatively, various types of resin materials can be applied to the conveying surface provided by the helical turns of the conveyor belt. For example, by extruding a thermoplastic resin, which can be done by placing a portion of the helical path of the conveyor belt into an extrusion nozzle or crosshead designed for extruding a cylindrical body of softened thermoplastic resin material onto the moving surface. Preferably, the apparatus is of such a length that the resin material is expected to harden while still supported on the surface formed by the conveyor belt. In the case of a thermoplastic resin, this hardening can be accelerated by the use of cooling means. In various uses of the equipment, the support structure for the conveyor belt can be either mounted in a rotatable manner or mounted in a non-rotational manner, as will be explained in more detail later. The continuous support provided by the conveyor belt results in plastic pipes, manufactured either by extrusion or winding, on the outer surface of the conveyor belt being perfectly smooth and curved on the inside. The outer surface of the core pipe is polished and, as mentioned, is not provided with any radially protruding support device (like the previously mentioned core pipe). Therefore, it is very lightweight. In one embodiment of the equipment, where the core pipe is mounted to rotate about its longitudinal axis, it is contemplated that the drive devices are arranged so that they can rotate the core pipe at a circumferential speed equal to, and rotate in the opposite direction compared to, the turns of the belt, when the speed is measured at the cross-section of the core pipe, in view of which the turns occur only axially along the outer surface of the core pipe. This version is especially advantageous when the manufactured plastic pipe, as delivered from the equipment, is required to be mounted or placed on the ground and therefore must not be rotated. The core pipe may be of a robust cantilever construction resting on a central hollow shaft that is open at its outer end through which the conveyor belt can pass after leaving the outer surface of the core pipe, and in which shaft there may be a hole through which the conveyor strip is pulled so that it can reach some guides for engaging and directing the belt towards the outer surface Lnoznn / zznz / e / YiAi of the core pipe at its innermost end. The drive devices may comprise a motor provided with a gear device coupled to the shaft. All technically possible combinations and / or permutations, as well as duplications of the functional and / or material parts of the device and the changes associated with them, are considered to be disclosed in at least one of the method or method stages. Since the characteristics of the process are revealed in the preceding text or in the subsequent description of the figures, the latter are also considered to be revealed as characteristics of the method and vice versa. Other advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and with the aid of the drawings. In the figures: Figure 1 shows a schematic representation of an embodiment of an apparatus according to the invention in a side view, Figure 2 shows a schematic representation of a portion of a return head of the device in a front view, and Figure 3 shows the return head of Figure 1 in a side view. The apparatus 20 according to the invention in Figure 1 comprises a drive housing 1, an impeller guide cam plate 2, a steel belt impeller 3, a set of several mandrel discs 4, spacer tubes 5, aluminum beams 6, a steel belt tensioning apparatus 9, a steel belt return tube 10, and a main shaft 11. The mandrel discs 4 are plates mounted on a central rotating shaft. For better representation, Figure 1 also shows a cross-sectional view of the apparatus 20 in order to illustrate the mandrel discs 4, the spacer tubes 5, the aluminum beams 6, and the main shaft 11. An endless steel belt 8 (also called a conveyor belt) is wound around mandrel discs 4 (also called a support structure) to form the outer surface of a mold for a resin, which is applied onto the steel belt 8. After the resin is applied onto the mold, the resin cures to form the resin tube. The conveyor strip 8 exits the mold, enters the hollow rotary mold, and returns to the start of the apparatus 20 to form the mold surface again. Lnoznn / zznz / e / YiAi The apparatus 20 further comprises a steel belt return head 7. The return head 7 carries the conveyor belt 8 when the conveyor belt 8 exits the mold and enters the hollow rotary mold to return to the start of the support structure 4. The steel belt 8 is pushed forward by a motor (not shown) inside the drive housing 1. After passing the right end of the apparatus 20, the belt 8 is fed into the hollow interior of the apparatus 20. The endless steel belt 8 passes through the interior of the support structure 4 and exits the apparatus 20 at its left end, from where it is redirected to the outer surface of the mandrel discs 4. A spring-loaded rail ensures that the belt 8 is under proper tension. Figure 2 shows a schematic representation of a section of the return head 7 in a front view, and Figure 2 shows the return head 7 of Figure 1 in a side view. The return head 7 comprises variable-length elements 12, 13 for supporting the conveyor belt 8. In this embodiment, the variable-length elements 12, 13 comprise pressure elements, the pressure elements comprising movable pistons 12 and rollers 13. The rollers 13 are arranged at the radial outer ends of the pistons 12. The pistons 12 can move radially between an inner radial position (the two pistons 12 on the left side) and an outer radial position (the two pistons 12 on the right side). Therefore, the pistons 12 can move radially with respect to the axis extending through the interior of the apparatus 20. The return head 7 further comprises a return head disc 14. The return head disc 14 extends perpendicular to the longitudinal axis of the support structure 4. The pistons 12 can move in the cylinders 15, which in turn are fixed to the disc 14 by means of clamps 16. The clamps 16 are fixed to the disc 14 by means of bolts 17 which are received and secured in the openings 18 of the disc 14. During operation, the return head 7, with its variable-length support pistons 12, follows the conveyor belt 8, i.e., the mold. The lengths of the pistons 12 vary depending on the mold pitch and the preselected maximum and minimum distances to the center point of the rotating shaft. The pistons Lnoznn / zznz / e / YiAi are designed to automatically return to their maximum length, this length being equal to the greatest distance from the center of the rotating shaft required for the mold geometry. The pipe mold, with the manufactured pipe laminate, restricts the full extension of the pistons 12. Therefore, the pistons 12 exert a force on the steel strip against the GRP laminate, maintaining the tension and position of the steel strip. The minimum length of the pistons 12 is defined by the minimum required distance of the mold from the center axis of the rotating shaft. The pistons 12 can thus follow the external geometry of the mold and support the steel band in all positions throughout the movement from the minimum to the maximum extension of the pistons 12. The position of pistons 12 is controlled by suitable means and may include, but is not necessarily limited to, pneumatic, 15 elastic, hydraulic, magnetic or mechanical position control. List of reference numbers: drive housing, impeller guide cam plate, steel belt impeller, mandrel disc, spacer tube, aluminum beams, steel belt return head, steel belt, steel belt tensioning apparatus 10 steel band return tube main shaft 12 pistons 13 rollers 14 return head disk 15 cylinders 16 clamps 17 bolts 18 openings Lnoznn / zznz / e / YiAi 20 Apparatus for producing tubes

Claims

1. Apparatus (20) for producing resin tubes, the apparatus (20) having a hollow support structure (4), in which an endless conveyor strip (8) can be wound around the outside of the support structure (4) in a plurality of adjacent windings to form a mold, the apparatus (20) comprising application means for applying a resin material to the outside of the mold, the apparatus (20) further comprising a return head (7) for supporting the conveyor strip (8) after it leaves the support structure (4) and for feeding the conveyor strip (8) into the interior of the support structure (4), characterized in that the return head (7) comprises elements of variable length (12, 13) for supporting the conveyor strip (8).

2. Apparatus (20) according to claim 1, wherein the variable length elements (12, 13) comprise pressure elements for pressing the conveyor strip (8) radially outwards.

3. Apparatus (20) according to at least one of the preceding claims, wherein the variable length elements (12, 13) comprise adjustable length support rods.

4. Apparatus (20) according to at least one of the preceding claims, wherein the variable length elements (12, 13) comprise conveyor strip supports (13), preferably rollers, mounted on the radial outer ends of the movable pistons (12).

5. Apparatus (20) according to at least one of the preceding claims, wherein the variable-length elements (12, 13) can be moved in radial directions, especially between the inner and outer positions.

6. Apparatus (20) according to at least one of the preceding claims, wherein the variable-length elements (12, 13) can be moved on cylinders (15) fixed to a return head disk (14) extending perpendicular to a longitudinal axis of the support structure (4).

7. Apparatus (20) according to at least one of the preceding claims, wherein the variable length elements (12, 13) vary between preselected maximum and minimum distances depending on the radial distance between the conveyor belt (8) and the longitudinal axis of the support structure (4).

8. Apparatus (20) according to at least one of the preceding claims, wherein the variable length elements (12, 13) exert forces on the conveyor strip (8) against the resin material and maintain the tension and position of the conveyor strip (8).

9. Apparatus (20) according to at least one of the preceding claims, wherein the variable length elements (12, 13) comprise pneumatic, elastic, hydraulic, magnetic and / or mechanical actuators.

10. A method for producing resin tubes, especially using an apparatus according to at least one of the preceding claims, wherein an endless conveyor strip (8) is wound around the outside of a hollow support structure (4) in a plurality of adjacent windings to form a mold, wherein a resin material is applied to the outside of the mold, wherein a return head (7) supports the conveyor strip (8) after it leaves the support structure (4) and feeds the conveyor strip (8) into the interior of the support structure (4), characterized in that the return head (7) comprises elements of variable length (12, 13) for supporting the conveyor strip (8).

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