APPARATUS AND METHOD FOR FORMING AN ELONGATED ARTICLE

Abstract: Apparatus and method for forming of elongated metal articles comprising one or more rotating dies (1) provided with an identation (3), being complementary shaped to the actual final shape of the resulting articles, where the dies (1) are designed and adapted to ensure/allow three rotational degrees of freedom under deformation by rotation of the dies.

Description: APPARATUS AND METHOD FOR FORMING AN ELONGATED ARTICLE The present invention relates to apparatus and method for forming an elongated metal article and more particularly to apparatus and method allowing three- dimensional forming of articles in a single one step process. Numerous patent publications are known disclosing apparatuses and associated methods of forming elongated articles in multistage processes to convert e.g. extruded tubular Al-shapes into finished articles of desired configuration by stretching of the Al-shapes beyond the yield point of the material and subsequently/simultaneously employing a set of dies resulting in bending of the shapes. However, all the hitherto known apparatuses do not assure a reliable, precise and economical manufacturing of three-dimensionally reshaped articles in one single operation without need for exchange and/or use of additional forming means (tools). Consequently, it is an object of the present invention to provide a novel, effective method for forming of elongated metal articles, particularly three-dimensional forming, in one single operation. Another object of the present invention is to provide a novel, effective integrated apparatus without need for additional forming means. These and other objects and advantages of the novel apparatus and method of forming according to the present invention are met by provision of an apparatus and associated method of manufacturing as it appears from the attached independent claims 1 and 4, respectively. The invention will now be described in more details by way of example(s) of preferred embodiment(s) of the apparatus and preferred mode of operation and illustrated by the accompanying drawings, Figs. 1-2, where Fig. 1 illustrates schematically in a perspective view the operational principle of applying a novel apparatus according to the present invention, Figs. 2a,b show schematically in a perspective view a more detailed configuration of another embodiment of the novel apparatus applicable according to the present invention in the start and final position of the operation, respectively. The forming apparatus according to the present invention has basically four degrees of freedom: Rotation about three axes and translation in one direction to reduce or increase the length of the article to be formed optionally. The apparatus may be extended to have three rotational degrees of freedom and three transitional degrees of freedom (orthogonal/Cartesian system). The additional translation may help forming of complex parts or impose shear deformations. The principle utilized by this apparatus is to fix each end of the elongated metal article to the die. By moving the dies simultaneously/non-simultaneously along one or more of the rotational axes and/or by translating them, the starting profile/shape is gradually forced into a track (this die part is replaceable, hence the equipment is flexible) in the die determining the final shape of the product. It is important to stress that dies may be moved in everything from one to six of the degrees of free- dom during a forming operation. It is also possible to alter the sequence of the movements of the dies and to suppress one or more of the degrees of freedom, dependent on what is needed for the product to be produced. The rotational degrees of freedom may be provided/ensured simply by movements around a spherical joint as illustrated in Fig. 1. However, according to another preferred embodiment of the apparatus it is also possible to separate each of the rotational degrees of freedom into independent or dependent movements having a common or a non-common centre of rotation, or they may be a combination of translations and rotations, i.e. one or more of the rotational degrees of freedom may be dependent on other movements as shown in Fig. 2. Referring to the drawings, and particularly to Fig. 1 , the surface of the die 1 is provided with an indentation or track 3 corresponding to the final form of the product. The section may be supported on one, two or three sides along the track that are engaging into contact with the processed member 10 (profile, extrusions, metal part etc.). An initially straight member 10 is placed into the tool while this is in its upper position. By fixing the ends of the section either by a press or another clamping arrangement (not shown in the Figure), it is possible to rotate the die(s) so that the section gradually is forced into the track 3 in the die. In the final forming step the die will be in the position illustrated in Fig. 1. The rotation from the initial stage to the final stage may take place about three independent axes, to take care of bending in the vertical plane, bending in the horizontal plane and twisting of the section. It is important to emphasise that the two dies are not restricted to make the same movement. In some cases, for example, it is possible to fix one of the dies, and just use one side of the tool to bend a section. The fixed die is just used to support the part of the section that is not to be changed during the forming operation. Die upper parts of the tool support the dies that are in contact with the product (track for the final product). The shown die parts rest on a spherical joint 2, allowing rotation about three axes. The shown die part is also supported by a mechanism 4 that can be used to control the movement around the sphere. The whole apparatus is resting on plates 5 that can move back and forth on the lower plate (not shown in the Figure). This allows the two main die parts to be moved away or towards each other, allowing for an increase or reduction in tension during the bending. Fig. 2a illustrates schematically the preferred embodiment of the apparatus having the four basic degrees of freedom separated in a start position of the (re)forming operation (only half part shown in the Figure). The base plate 5 can be moved back and forth to impose additional tension or compression into the article 10 to be bent. A cylindrical bearing 2 and its support 7 extending from the base plate ensure rotation in a horizontal plane. On the cylindrical bearing support a bolt 9 is mounted to take care of die rotations in a vertical plane of the die. The last movement, twisting (torsion) of the section, is placed inside a stiffener member 8 supporting the die 1 having a track 3 that is in contact with the elongate metal article to be formed 10. It should be noticed that the Figure only shows one half of the bending apparatus. Additionally, the translation movement indicated by 6 and 6' is possible degrees of freedom to impose shear deformation or to increase the complexity of the product to be formed. Fig. 2b shows schematically in a partial perspective view the apparatus in final position after termination of the bending/stretching operation with the die 1 resting on the base plate 5. The original extruded article 10 from Fig. 2a is now converted/translated into a final product 12 (only half part shown in the Figure) having the desired outer configuration. Thanks to the novel apparatus according to the present invention, which offers mutually independent movement of the dies and thus a complete independent movement freedom along a predetermined path for the respective ends of the shaped to be metal articles, more intricate complete configurations of the articles can be provided in one single (re)forming operation. The dies may, but do not need to, rotate along certain axes rotating in the latter case around one or more points. The movements may be controlled by any known powering mechanism, i.e. hydraulically, electrically, mechanically initiated movement. It is also possible to place the tool inside a press and let the movement of the press determine the die movements. The latter may also open for additional tool parts placed together with the proposed forming tool to make holes, imprints and so on.

Claims: Claims 1. Apparatus for forming of elongated metal articles comprising - one or more rotating dies (1) provided with an indentation (3), the indentation being complementary shaped to the actual final shape of the resulting articles, - fastening means for fixation of the articles prior to the forming operation, characterized in that the dies (1) are designed and adapted to ensure/allow three rotational degrees of freedom moving independently of each other. 2. Apparatus according to claim 1 , characterized in that the rotational freedom is ensured by means of spherical bearings (2) supporting the dies (1). 3. Apparatus according to claim 1 , characterized in that a cylindrical bearing (2) and a stiffener member (8) supporting the die (1) are provided to ensure the horizontal and torsional degree of freedom. 4. A method of forming elongated metal articles comprising steps of positioning and fastening of elongated metal members (10) onto ratable dies (1), stretching of the fastened metal members and simultaneous bending of the members by a mutually independent rotation of the dies in a single plan or two plans, and finally terminating of the bending step and release of the fastened provided reshaped metal articles. Method according to claim 4, characterized in that all movements of the forming parts (tool) are controlled by the vertical movement of the applied press.

Inventors: PAULSEN FRODE, ROEE SIGMUND, PAULSEN, FRODE, ROEE, SIGMUND
Applicants: NORSK HYDRO AS, PAULSEN FRODE, ROEE SIGMUND, NORSK HYDRO ASA, PAULSEN, FRODE, ROEE, SIGMUND
Application year: 2001
Main classification: B21D7
IPC codes: B21D7