MX2008010348A - Method for producing a plastic hollow body with built-in parts and a plastic container with built-in parts - Google Patents

Abstract

The invention relates to a method for producing an article that encloses built-in parts and has the form of a hollow body made of thermoplastic material. The hollow body is advantageously embodied as a fuel container. The method comprises the extrusion of one or several web-type or tubular preforms (13) of plastified material, said preforms being pressed against the open parts of a moulding tool (9a, 9b) forming a cavity. At least one built-in part (1) to be enclosed by the finished article is placed between the parts of the moulding tool (9a, 9b), the tool being closed around the preforms (13) and the built-in part (1). The preforms (13) take the exterior form of the article within the cavity enclosed by the tool. The built-in parts (1) are pressed against the inner wall (4) of the material that is still plastic during or immediately after the moulding process, so that the plastic of the hollow body penetrates and flows into at least one recess or opening of the built-in part (1).

Description

METHOD TO PRODUCE A PLASTIC HOLLOW BODY WITH BUILT-IN PARTS AND A PLASTIC CONTAINER WITH RECESSED PARTS DESCRIPTIVE MEMORY The invention relates to a process for the production of a hollow plastic body and a plastic container. The most widely varying production processes are known in terms of the production of hollow bodies of thermoplastic material, for example blow molding with extrusion, deep drawing or injection molding. In the extrusion blow molding process, the hollow body can be produced without connecting lines, for example a simple tubular preform. It will be noted, however, that there is also the possibility of dividing a tubular preform into tapes in accordance with the length, placing the tapes separately in a two-part or multi-part tool and expanding or forming them inside the tool or by means of pressure reduced or subjected to the action of a gas pressure. Particularly in the production of the technical components, such as fuel tanks that are produced in the manner described above in one or more parts based on thermoplastic material, there is a need to be fixed several recessed or installation parts or mounting parts to the hollow body. This can be done at the first heating in the production process or also subsequently. If the hollow body is designed to receive the installation parts therein, it is often necessary, by virtue of the size of the installation parts, to enter the hollow body in the production thereof. The installation or mounting parts that must be inserted or inserted into the hollow body can be cut out or welded to the hollow body, in which case the welding operation can be carried out in the production of the hollow body at the first heating or subsequently at the second heating, for example by friction welding or welding with heat reflector. Limits are often imposed on the securing of an installation part in positive locking relationship within the hollow body by virtue of the production procedure thereof. For example, when hollow bodies are produced by an extrusion blow molding process, it is only possible to provide in the outline of the hollow body with slanted cutting configurations that allow the installation parts to be locked to the hollow body wall in relation to the hollow body. positive block For this reason, welding is frequently referred to as joining procedures. The welding of the components to each other however suffers from the disadvantage that the plastic materials to be connected must form a pairing of material that can be welded together. This limits the choice of installation or mounting parts for the hollow body. As an example in the production of fuel tanks based on plastic material, this can represent a serious limitation since, in the presence of fuel, certain plastic materials swell or are permeable to hydrocarbons. Certain ducts and valves therefore require a choice of material that excludes the possibility of welding the container or tank or the hollow body from the beginning. Therefore the object of the invention is to provide a process for the production of an article that includes installation parts in the form of a hollow body of thermoplastic material, which allows particularly simple and secure fixing of the installation parts in the hollow body in the course of the production of them. A further object of the invention is to provide a hollow plastic body to which the installation parts or mounting parts in positive locking relationship are connected in a particularly simple manner. This object is achieved in the first place by means of a process for the production of an article that surrounds installation parts in the form of a hollow body of thermoplastic material, in which one or more preforms in the form of a tape or a tube of plastic material are disposed between the open parts of a molding tool that forms a cavity, at least one part of the installation to be wrapped with the finished article is placed between the parts of the molding tool and the tool is closed around the preforms and the installation part and the preforms acquire the external configuration of the article within the cavity enveloped by the tool, where the installation part is tightened during the forming, or directly after it, against the inner wall of the article while still in the plastic state, so that the plastic material of the hollow body passes through at least one concavity or opening of the installation part and flows behind it. In this way it is possible to allow the installation part to be fastened to the wall of the hollow body in relation to the positive lock using comparatively simple means. The inner wall of the hollow body passes through and flows behind a securing opening in the installation part, so that a positive and non-releasable locking connection is achieved, after the components are cooled. There is no need for material compatibility in the sense of welding capacity of the parts. The installation part can also comprise, for example, metal or other material. Due to the given configuration of the opening in the installation part, the wall material of the hollow body, w flows through the opening to the installation part, preferably constitutes a head that maintains the connection similarly to a rivet head . In a preferred variant of the method, the operation of pressing the installation part against the inner wall of the article is carried out. without lost aids that had been removed from the article again, for example after the article has been completed. In a particularly preferred variant of the method according to the invention, the head of the connection is formed without auxiliary means for producing the deflection (w restricts the plastic material of the wall of the hollow body, w flows into the opening). Conveniently, two tape-shaped preforms are extruded between the open halves of a two-part mold for blow molding, wherein the mold halves are first closed against an installation carrier frame disposed therebetween, disposed therein. of the installation carrier frame there are means for positioning installation parts, with w the installation part is pressed out of the plane of the frame against the inner wall of the article and where in an additional process step the frame is removed of carrier of the installation part and the mold halves are closed against each other to finish the article. The last step of the procedure allows the welding of the two halves of the article while they are still in the first heating. It will be appreciated by those skilled in the art that it is also possible to provide an installation carrier plate in place of an installation carrier frame. Furthermore, the installation carrier frame must not necessarily be in the form of an open or uncovered element. The object of the invention is furthermore achieved with a hollow plastic body having at least a portion of installation or of assembly, w is connected to the hollow body in the production thereof, wherein the hollow body and the installation or assembly part are connected to each other in positive locking relationship, in such a way that the installation or assembly part in the The region of its contact surface with the wall of the hollow body has at least one continuous opening through w the plastic material passes from the wall of the hollow body and behind w said plastic material is joined. The continuous opening is conveniently in the form of a circular bore. Alternatively, the continuous opening may be profiled, w is advantageous in particular when the installation part has only one continuous opening and a unique orientation of the installation part in relation to the wall of the hollow body is desired. Preferably, the plastic material passing through the continuous opening forms an enlarged head in the installation or assembly parts that allows the two components to be secured in a positive locking relationship. According to a preferred variant of the plastic hollow body according to the invention, the installation part is allowed to have at least one base element which forms a contact surface in relief or stepped with the wall of the hollow body. In this way, with the same clamping force, the pressure is increased in relation to the surface area on the wall of the hollow body in the region of the contact surface. The base element (s) produces a punch action that reinforces the flow of the thermoplastic material from the hollow body wall to the continuous opening. The continuous opening passes conveniently through the contact surface of the base element. In a variant of the plastic hollow body, the contact surface of the base element is concave or conical in configuration and the continuous opening forms approximately the deepest location of the concave configuration, thereby positively influencing the movement flow of the plastic material of the hollow body wall through and behind the continuous opening. In a further convenient configuration of the hollow plastic body, the continuous opening is allowed to be of a biased configuration at its end that is remote from the wall of the hollow body. The skewed cut shape forms the support means for the enlarged head of the molten shoulder when it has cooled. If the hollow plastic body according to the invention is thus in the form of a fuel tank, the installation parts of the fuel tank can be equipped with a plurality of base elements in the manner described above. Accordingly, the increase in the number and distribution of the connection locations makes it possible to achieve a connection or securing of the installation parts inside the fuel tank, the connection or securing being safe and reliable for any operating condition of the fuel tank. Motor vehicle. The invention is described hereinafter by means of an example mode illustrated in the drawings, in which: Figures 1 and 2 show a schematic view of the connection of an installation part of the wall of the hollow body, and Figures 3 to 12 show a schematic view of the production process for the fuel tank of plastic material according to the invention.

Reference list 1 Installation part 2 Base element 3 Continuous opening 4 Wall 5 Head 6 Contact surface 7 Skew configuration 8 Article 9a, 9b Mold halves 10 Mold cavity 1 1 Installation carrier frame 12 Part holder 13 Preforms As illustrated in a simplified manner in FIGS. 1 and 2, the installation part 1 shown in the section has a base element 2 with a continuous opening 3.

As already mentioned above, the method according to the invention is described hereinafter by way of example with reference to the production of the fuel tank of plastic material. The invention is to be interpreted however in such a way that any hollow body can be produced at all. The connection can be made both inside and outside the hollow body. In the present case, the installation part 1 is in the form of a sudden variation vessel in a fuel tank. The installation part 1 shown in FIG. 1 is tightened with its base element 2 against the wall 4 of the hollow body to be produced, more specifically when the plastic material of the wall 4 is still or is again in the plastic state. In the production process described hereinafter, the connection is made in the first heating in the production of the hollow body, so that the material of the wall 4 is still in the molten state and, when sufficient pressure is applied to the element of base 2 in the direction of the arrow shown on the right in figure 1, the material of the wall 4 forms the head 5 shown in figure 2 and which is connected behind the continuous opening 3 in the installation part 1 The continuous opening 3 is preferably in the form of a round bore that is chamfered or slanted cut at its remote end of the wall 4. For the purpose of improving the flow characteristics of the plastic material, the base member 2 has a concave surface of contact 6 having a continuous opening 3 passing through it centrally, that is to say in the deepest location of its hollow configuration. That conformation of the contact surface 6 and the base element 2 which is stepped in relation to the installation part 1 by means of the flow characteristics of the molten material through the continuous opening 3. With a given clamping force, the stepped configuration of the base element 2, in the form of a punch, increases the pressure in relation to the surface area in the region of the contact surface. The concave configuration of the concave surface in conjunction with the increased pressure relative to the surface area occurring there causes the molten material to be directed to the continuous opening 3. On its remote side from the contact surface 6, the continuous opening 3 is provided with a biased cutting configuration 7 which serves as a support means for the head 5. The head is made even if the skewed cut-out configuration 7 is not present, it being necessary then in some circumstances to make the thickness of the element smaller 2. As already mentioned above, the procedure according to the invention is shown schematically in Figures 3 to 12. The method according to the invention includes the production of article 8 in the form of a fuel tank by blow molding. with extrusion. The molding tool includes two mold halves 9a, 9b which are of mutually complementary configuration and which in the condition Closed define a mold cavity 10 that determines the external configuration of the article 8 to be produced. Positioned between the mold halves 9a, 9b is an installation carrier frame 1 1 which is movably disposed between the mold halves 9a, 9b: The installation part fasteners 12 are disposed variablely in position within the carrier frame of the carrier. installation 1 1. They are displaceable or adjustable within the installation carrier frame 1 1 by hydraulic or pneumatic means in the plane of the installation carrier frame and transversely thereto. The fasteners of the installation part 12 are provided with the installation part 1, as shown in figure 4. In the present case, the installation parts 1 are connected to each other by means of a line that is not identified with greater detail. Each of the installation parts is approximately of the configuration shown in Figures 1 and 2. After the installation carrier frame 1 1 has been positioned between the mold halves 9a, 9b, the preforms 13 in ribbon form they are extruded between the open mold halves 9a, 9b of one or more extrusion heads (not shown). It is also possible that the preforms 13 are not extruded at the place of installation of the tool, but remotely thereof and that they move into position between the open mold halves 9a, 9b with a handling apparatus. The preforms 13 extend respectively in the position shown in figures 5 and 6 between a mold half 9a, 9b and the frame of installation carrier 1 1. In an additional process step, the preforms are applied by means of a reduced pressure against the contour of the mold halves 9a, 9b in the mold cavity 1 1. This can be done with the closing of the mold halves 9a, 9b against the installation carrier frame 1 1, or it may have already been made previously. The preforms 13 are made to rest completely against the contour of the mold cavity 10 by means of increased pressure. The installation part fasteners 12 move after the plane of the frame and tighten the installation parts 1 against the wall 4 of the article 8 or against the preforms that bear against the mold cavity 10. The fastening effect described takes place above for the installation parts 1 to the wall 4 of the article 8. The installation part fasteners 12 are then moved back to their starting potion. The mold halves are separated one from the other, in which case the recessed half-piece portions formed previously of article 8 remain in the mold cavity. The installation carrier frame 1 1 is moved between the mold halves 9a, 9b, the tool is closed again and welds the two portions of a suitable half part of the article together. The shaping operation and the removal of the finished article 8 are illustrated schematically in Figures 11 and 12.

Claims (8)

NOVELTY OF THE INVENTION CLAIMS

1 .- A procedure for the production of an article that wraps installation parts in the form of a hollow body of thermoplastic material, in which one or more preforms are arranged in the form of a tape or plastic plastic tube between the open parts of a molding tool forming a cavity, at least one installation part for wrapping between the parts of the molding tool is placed and the tool is closed around the preforms and the installation part and the preforms acquire the external configuration of the article inside the cavity enveloped by the tool, where the installation part is tightened during the forming, or directly after it, against the inner wall of the article, while still in the plastic state, so that the plastic material of the hollow body pass at least through a concavity or opening in the part of the installation and flow behind it.

2. The method according to claim 1, further characterized in that the operation of tightening the installation part against the interior wall of the article without lost auxiliary means.

3. - The method according to any of claims 1 and 2, further characterized in that two preforms are extruded or arranged in the form of a ribbon between the open halves of a two-part mold for blow molding, where the mold halves against an installation carrier frame disposed therebetween, means for positioning installation parts are arranged within the installation carrier frame, with which the installation part is pressed out of the plane of the frame against the inner wall of the article, and wherein in an additional procedural step the component carrier frame is removed and the mold halves are closed against each other to finish the article.

4. - A hollow plastic body having at least one installation or assembly portion, which has been connected to the hollow body during the production thereof, wherein the hollow body and the installation or assembly part are connected each other in positive locking relationship, such that the installation or mounting part in the contact surface region (6) with the wall (4) of the hollow body has at least one continuous opening (3), a through which passes the plastic material of the wall (4) of the hollow body and behind which said plastic material is connected.

5. - A hollow plastic body according to claim 4, further characterized in that the installation or assembly part has at least one base element (2) that forms a surface of contact (6) in relief or stepped with the inner wall (4) of the hollow body.

6. - A hollow plastic body according to claim 5, further characterized in that the continuous opening (3) passes through the contact surface (6) of the base element (2).

7. - A hollow plastic body according to any of claims 4 to 6, further characterized in that the contact surface (6) is of concave or conical configuration and the continuous opening (3) approximately forms the deepest location of the cupped configuration.

8. - A hollow plastic body according to any of claims 4 to 7, further characterized in that the continuous opening (3) is of biased configuration and its remote end of the wall (4) of the hollow body.