Title of Invention

METHOD FOR PRODUCING A PLASTIC HOLLOW BODY WITH BUILT-IN PARTS AND A PLASTIC CONTAINER WITH BUILT-IN PARTS

Abstract

The invention concerns a process for the production of an article enclosing installation parts in the form of a hollow body of thermoplastic material. The hollow body is preferably in the form of a fuel tank. The process includes the extrusion of one or more preforms in web or tube form of plasticised plastic material between the opened parts of a moulding tool forming a cavity, wherein at least one installation part to be enclosed by the finished article is placed between the parts of the moulding tool and the tool is closed around the preforms and the installation part, wherein the preforms acquire the external configuration of the article within the cavity enclosed by the tool. The installation part is pressed against the inside wall of the article while still plastic during or immediately after the shaping operation so that the plastic material of the hollow body passes through at least one recess or opening of the installation part and flows therebehind.

Full Text

The invention concerns a process for the production of a plastic hollow body and a plastic container. The most widely varying production processes are known for the production of hollow bodies of thermoplastic material, for example extrusion blow moulding, deep drawing or injection moulding. In the extrusion blow moulding process the hollow body can be seamlessly produced for example from a single tubular preform. It will be noted however that there is also the possibility of dividing a tubular preform into webs according to length, placing the webs separately in a two-part or multi-part tool and expanding or shaping them within the tool by means of a reduced pressure or by subjecting them to the action of a gas pressure. Particularly in the production of technical components such as fuel tanks which are produced in the above-described manner in one or more parts from thermoplastic material, there is a need for various built-in or installation parts or attachment parts to be fixed to the hollow body. That can be effected in the first heat in the production procedure or also subsequently. If the hollow body is intended to receive the installation parts in its interior, it is often necessary, by virtue of the size of the installation parts, for them to be introduced into the hollow body in the production thereof. The installation or attachment parts which are to be introduced or attached to the hollow body can be clipped or welded to the hollow body, in which case the welding operation can be effected in production of the hollow body in the first heat or subsequently in the second heat, for example by friction welding or heat-reflector welding. Limits are often imposed on anchoring an installation part in positively locking relationship in the interior of the hollow body by virtue of the production process thereof. For example, when producing hollow bodies by an extrusion blow moulding process, it is only limitedly possible to provide in the contour of the hollow body, undercut configurations which permit installation parts to be locked to the wall of the hollow body in positively locking relationship. For that reason recourse is frequently had to welding as a joining procedure. Welding the components together however suffers from the disadvantage that the plastic materials to be connected must form a material pairing which can be welded together. That limits the choice of the installation or attachment parts for the hollow body. By way of example, in the production of fuel tanks from plastic material, this can represent a serious limitation as, in the presence of fuel, certain plastic materials swell or are permeable for hydrocarbons. Certain conduits and valves therefore require a choice of material which excludes the possibility of welding to the container or tank or to the hollow body, from the outset. Therefore the object of the invention is to provide a process for the production of an article including installation parts in the form of a hollow body of thermoplastic material, which permits particularly simple and secure fixing of installation parts in the hollow body in the course of production thereof. A further object of the invention is to provide a plastic hollow body to which installation parts or attachment parts are connected in positively locking relationship in a particularly simple fashion. That object is firstly attained by a process for the production of an article enclosing installation parts in the form of a hollow body of thermoplastic material, in which one or more preforms in web or tube form of plasticised plastic material are disposed between the opened parts of a moulding tool forming a cavity, at least one installation part to be enclosed by the finished article is placed between the parts of the moulding 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 enclosed by the tool, wherein the installation part is pressed during or directly after shaping against the inside wall of the article while still plastic so that the plastic material of the hollow body passes through at least one recess or opening in the installation part and flows therebehind. In that way it is possible to provide that the installation part is anchored to the wall of the hollow body in positively locking relationship using comparatively simple means. The inside wall of the hollow body passes through and flows behind an anchoring opening in the installation part so that a positively locking and non-releasable connection was achieved after cooling of the components. There is no need for compatibility of the materials in the sense of weldability of the parts. The installation part can for example also comprise metal or another material. Due to the shaped configuration of the opening in the installation part, the material of the wall of the hollow body, that flows through that opening into the installation part, preferably forms a head which holds the connection similarly to a rivet head. In a preferred variant of the process, the operation of pressing the installation part against the inside wall of the article is effected without lost aids which would have to be removed from the article again for example after the article is finished. In a particularly preferred variant of the process according to the invention the head of the connection is formed without aids for producing deflection (restraining the plastic material of the wall of the hollow body, that flows into the opening). Desirably two preforms in web form are extruded between the opened halves of a two-part blow moulding mould, wherein the mould halves are firstly closed against an installation carrier frame arranged between them, arranged within the installation carrier frame are means for positioning installation parts, with which the installation part is pressed out of the plane of the frame against the inside wall of the article, and wherein in a further process step the installation part carrier frame is removed and the mould halves are closed against each other to finish the article. The last process step provides for welding of the two halves of the article while still in the first heat. It will be appreciated by the man skilled in the art that it is also possible to provide an installation carrier plate in place of an installation carrier frame. The installation carrier frame moreover does not necessarily have to be in the form of an open or opened element. The object of the invention is further attained by a plastic hollow body having at least one installation or attachment portion, which was connected to the hollow body in the production thereof, wherein the hollow body and the installation or attachment part are connected together in positively locking relationship in such a way that the installation or attachment part in the region of its contact surface with the wall of the hollow body has at least one through opening through which passes the plastic material of the wall of the hollow body and behind which said plastic material engages. The through opening is desirably in the form of a circular bore. Alternatively the through opening can be profiled, which is advantageous in particular when the installation part has only one through opening and a unique orientation of the installation part in relation to the wall of the hollow body is desired. Preferably the plastic material which passes through the through opening forms in the installation or attachment parts an enlarged head which provides for anchoring of the two components in positively locking relationship. In accordance with a preferred variant of the plastic hollow body according to the invention it is provided that the installation part has at least one foot element which forms a set-off or stepped contact surface with the wall of the hollow body. In that way, with the same pressing force, the pressure in relation to surface area on the wall of the hollow body is increased in the region of the contact surface. The foot element or elements produce a punch-like action which reinforces the flow of the thermoplastic material of the wall of the hollow body into the through opening. The through opening desirably passes through the contact surface of the foot element. In a variant of the plastic hollow body it is provided that the contact surface of the foot element is of a concave or conical configuration and the through opening forms approximately the deepest location of the trough configuration, whereby the flow movement of the plastic material of the wall of the hollow body through and behind the through opening is positively influenced. In a further desirable configuration of the plastic hollow body it is provided that the through opening is of an undercut configuration at its end which is remote from the wall of the hollow body. The undercut configuration forms the support means for the enlarged head of the molten projection when it has cooled. If the plastic hollow body according to the invention is for example in the form of a fuel tank, installation parts of the fuel tank can be equipped with a plurality of foot elements in the above-described manner. Accordingly, increasing the number and distribution of the connecting locations makes it possible to achieve a connection or anchoring of the installation parts in the interior of the fuel tank, with the connection or anchoring being secure and reliable for any operating condition of the motor vehicle. The invention is described hereinafter by means of an embodiment by way of example illustrated in the drawing in which: Figures 1 and 2 show a diagrammatic view of the connection of an installation part to the wall of the hollow body, and Figures 3 to 12 show a diagrammatic view of the production process for a fuel tank of plastic material according to the invention. As illustrated in highly simplified form in Figures 1 and 2 the installation part 1 shown in section has a foot element 2 with a through opening 3. As already mentioned hereinbefore the process according to the invention is described hereinafter by way of example by reference to the production of a fuel tank of plastic material. The invention however is to be interpreted in such a way that any hollow body whatsoever can be produced. The connection can be made both within and also outside the hollow body. In the present case the installation part 1 is in the form of a surge pot in a fuel tank. The installation part 1 shown in Figure 1 is pressed with its foot 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 heat in the production of the hollow body so that the material of the wall 4 is still in the molten state and, when a sufficient pressure is applied to the foot element 2 in the direction of the arrow shown at the right in Figure 1, the material of the wall 4 forms the head 5 which is shown in Figure 2 and which engages behind the through opening 3 in the installation part 1. The through opening 3 is preferably in the form of a round bore which is chamfered or undercut at its end remote from the wall 4. For the purposes of improving the flow characteristics of the plastic material the foot element 2 has a concave contact surface 6 which has a through opening 3 passing therethrough centrally, that is to say at the deepest location of its trough configuration. That shaping of the contact surface 6 and the foot element 2 which is stepped in relation to the installation part 1 promotes the flow characteristics of the molten material through the through opening 3. With a given pressing force, the stepped configuration of the foot element 2, in a punch-like form, increases the pressure in relation to surface area in the region of the contact surface. The concave configuration of the concave surface in conjunction with the increased pressure in relation to surface area that occurs there causes the molten material to be guided into the through opening 3. On its side remote from the contact surface 6 the through opening 3 is provided with an undercut configuration 7 serving as a support means for the head 5. The head is formed even if the undercut configuration 7 is not present, it is then necessary under some circumstances to make the thickness of the foot element 2 smaller. As already mentioned hereinbefore the process according to the invention is shown diagrammatically in Figures 3 to 12. The process according to the invention includes the production of the article 8 in the form of a fuel tank by extrusion blow moulding. The moulding tool includes two mould halves 9a, 9b which are of a mutually complementary configuration and which in the closed condition define a mould cavity 10 which determines the external configuration of the article 8 to be produced. Placed between the mould halves 9a, 9b is an installation carrier frame 11 which is arranged displaceably between the mould halves 9a, 9b. Installation part holders 12 are arranged variably in position within the installation carrier frame 11. They are displaceable or adjustable within the installation carrier frame 11 hydraulically or pneumatically in the plane of the installation carrier frame and transversely thereto. The installation part holders 12 are fitted with installation parts 1, as shown in Figure 4. In the present case the installation parts 1 are connected together by way of a line which is not identified in greater detail. Each of the installation parts is approximately of the configuration shown in Figures 1 and 2. After the installation carrier frame 11 has been positioned between the mould halves 9a, 9b preforms 13 in web form are extruded between the opened mould halves 9a, 9b from one or more extrusions heads (not shown). It is equally possible for the preforms 13 not to be extruded at the place of installation of the tool but remote therefrom, and to be moved into position between the opened mould halves 9a, 9b with a handling apparatus. The preforms 13 respectively extend in the position shown in Figures 5 and 6 between a mould half 9a, 9b and the installation carrier frame 11. In a further process step the preforms are applied by means of a reduced pressure against the contour of the mould halves 9a, 9b in the mould cavity 11. That can be effected with closure of the mould halves 9a, 9b against the installation carrier frame 11, or it can already be effected previously. The preforms 13 are caused to bear completely against the contour of the mould cavity 10 by means of reduced pressure or also by an increased pressure. The installation part holders 12 then move out of the plane of the frame and press the installation parts 1 against the wall 4 of the article 8 or against the preforms bearing against the mould cavity 10. The above-described anchoring effect for the installation parts 1 to the wall 4 of the article 8 takes place. The installation carrier holders 12 then move back into their starting position. The mould halves are moved away from each other, in which case the previously formed half-shell portions of the article 8 remain in the mould cavity. The installation carrier frame 11 is moved away between the mould halves 9a, 9b, the tool closes again and welds the two half-shell portions of the article together. The operation of shaping and removing the finished article 8 are diagrammatically illustrated in Figures 11 and 12. 1 installation part 2 foot element 3 through opening 4 wall 5 head 6 contact surface 7 undercut configuration 8 article 9a, 9b mould halves 10 mould cavity 11 installation carrier frame 12 installation part holder 13 preforms CLAIMS 1. A process for the production of an article enclosing installation parts in the form of a hollow body of thermoplastic material, in which one or more preforms in web or tube form of plasticised plastic material are disposed between the opened parts of a moulding tool forming a cavity, at least one installation part to be enclosed by the finished article is placed between the parts of the moulding 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 enclosed by the tool, wherein the installation part is pressed during or directly after shaping against the inside wall of the article while still plastic so that the plastic material of the hollow body passes through at least one recess or opening in the installation part and flows therebehind. 2. A process according to claim 1 characterised in that the operation of pressing the installation part against the inside wall of the article is effected without lost aids. 3. A process according to one of claims 1 and 2 characterised in that two preforms in web form are extruded or arranged between the opened halves of a two-part blow moulding mould, wherein the mould halves are firstly closed against an installation carrier frame arranged between them, arranged within the installation carrier frame are means for positioning installation parts, with which the installation part is pressed out of the plane of the frame against the inside wall of the article, and wherein in a further process step the component carrier frame is removed and the mould halves are closed against each other to finish the article. 4. A plastic hollow body having at least one installation or attachment portion, which was connected to the hollow body in the production thereof, wherein the hollow body and the installation or attachment part are connected together in positively locking relationship in such a way that the installation or attachment part in the region of a contact surface (6) with the wall (4) of the hollow body has at least one through opening (3) through which passes the plastic material of the wall (4) of the hollow body and behind which said plastic material engages. 5. A plastic hollow body according to claim 4 characterised in that the installation or attachment part has at least one foot element (2) which forms a set-off or stepped contact surface (6) with the inside wall (4) of the hollow body. 6. A plastic hollow body according to claim 5 characterised in that the through opening (3) passes through the contact surface (6) of the foot element (2). 7. A plastic hollow body according to one of claims 4 to 6 characterised in that the contact surface (6) is of a concave or conical configuration and the through opening (3) forms approximately the deepest location of the trough configuration. 8. A plastic hollow body according to one of claims 4 to 7 characterised in that the through opening (3) is of an undercut configuration at its end remote from the wall (4) of the hollow body.

Documents:

4139-CHENP-2008 AMENDED CLAIMS 23-08-2013.pdf

4139-CHENP-2008 CORRESPONDENCE OTHERS 08-01-2013.pdf

4139-CHENP-2008 EXAMINATION REPORT REPLY RECEIVED 23-08-2013.pdf

4139-CHENP-2008 FORM-3 23-08-2013.pdf

4139-CHENP-2008 OTHER PATENT DOCUMENT 23-08-2013.pdf

4139-chenp-2008 abstract.pdf

4139-chenp-2008 claims.pdf

4139-chenp-2008 correspondence-others.pdf

4139-chenp-2008 description(complete).pdf

4139-chenp-2008 drawings.pdf

4139-chenp-2008 form-1.pdf

4139-chenp-2008 form-3.pdf

4139-chenp-2008 form-5.tif

4139-chenp-2008 pct.pdf