Method and device for shaping details by means of superplastic forming

Abstract: This invention relates to a method and an apparatus for forming details by means of superplastic forming the foil or plate being heated to a suitable temperature and being simultaneously exposed to a fluid pressure so that the material is slowly deformed to a predetermined shape. The heating and hence the deformation of the foil or plate takes place locally by guiding a laser beam (17) over the surface of the foil or plate (12).

Description: This invention relates to a method and device for forming a detail by means of superplastic forming the foil or plate being heated to a suitable temperature and being simultaneously exposed to a fluid pressure so that the foil or plate slowly is deformed to a predetermined shape. It is previosly known to use superplastic forming in order to shape details. The method is described for instance in US-A-4181000 according to which a thin plate is fixed in a mould in which one mould part represents the shape of the finished detail the plate being heated to a temperature which is considerably below the melting point of the material - usually 50-80% of the melting point measured in Kelvin degrees - at the same time as the two surfaces of the plate are exposed to a comparatively limited pressure difference so that the material slowly, for instance during 10 minutes - 2 hours, flows out and is pressed towards said mould part and achieves a corresponding shape. The method has i.a. the advantage that when producing the detail only one mould part is needed which corresponds to the shape of the detail. A further prior art document, CH-A5-673603, describes a method and apparatus according to the pre-characterising parts of claims 1 and 6. The purpose of this invention is to improve the technique described above by completely eliminating the need for a mould part having a form corresponding to the shape of the detail. This is achieved by means of a device having the caracteristics mentioned in the claims. An embodiment of the invention will now be described with reference to the accompanying drawing in which Fig. 1 is a vertical section through a device according to the invention before the shaping procedure takes place whereas Fig. 2 shows the same section during the shaping procedure. The device shown in the Figures comprises a table 10 having fastening means 11 for a foil or a plate 12 of a material suitable for superplastic forming. Such materials are for instance zinc-, aluminium-, titanium-, steel- and copper-alloys and certain ceramic materials the thickness of the material preferably beeing 0,01-5 mm. Between the table 10 and the plate 12 a hermetically sealed chamber 13 is created which via a passage 14 is connected to a pressure source 15 so that gas or liquid under pressure can be supplied to the chamber 13. The pressure in the chamber 13 can be set or controlled in a suitable way preferably in the range of 2-30 bar. Above the table 10 a laser source 16 is arranged so that the laser beam 17 can be directed towards different areas on the plate. The laser source is for instance supported on a carriage 18 which can be moved in a horizontal plane in two directions which are perpendicular to each other. The movement of the carriage is guided by means of a microprocessor for instance arranged on the carriage. The device operates in the following way. A fluid under pressure is applied into the chamber 13 at the same time as a laser beam 17 during a period of some seconds to some minutes is directed to a particular area of the foil or plate 12 which means a spot formed heating of the plate. Due to a predetermined movement (which is controlled by the microprocessor) of the laser beam over the surface a certain area is locally heated to a suitable temperature in order to have the material to flow out under the influence of the pressure in the chamber 13. By choosing suitable time periods for the influence of the laser beam on different areas of the plate and at the same time having a suitable pressure in the chamber 13 the process can be controlled in such a way that the plate is deformed to a predetermined shape. It should be mentioned that it of course is possible to deform the plate under the influence of vacuum instead of using pressure above atmosphere as well as it is possible to apply different pressures on the two sides of the foil or plate whereby the pressure difference creates the shaping. This of course means that an additional pressure- or vaccum- chamber has to be arranged on the upper side of the foil or plate shown in the Figures the laser beam for instance entering through a window into the chamber. It is of course also possible to use a stationary laser source and direct the laser beam towards the working surface by means of mirrors and to control the mirrors and/or the fluid pressure in a suitable way according to a predetermined data program. The method according to the invention also has the advantage that it is time saving compared to conventional superplastic shaping methods since the entire plate and mould need not be heated.

Claims: Method for forming details by means of superplastic forming in which a foil or plate is heated to a suitable temperature and is simultaneously exposed to a fluid pressure such that the foil or plate is slowly deformed to a predetermined shape, characterized in that the heating and hence the deformation of the foil or plate takes place only locally and is by guiding a laser beam over the surface of the foil or plate. Method according to claim 1, characterized in that the laser beam is guided automatically by means of a microprocessor. Method according to claim 1 or 2, characterized in that the foil or plate material is one of zinc-, aluminium-, titanium-, steel- and copper alloys or ceramic materials, the material having a thickness of 0,01-5 mm. Method according to any of claims 1 - 3, characterized in that the heating is effected to 50-80% of the melting point of the foil or plate material measured in Kelvin degrees and that the pressure is 2 - 30 bar. Method according to any of the preceding claims, characterized in that the foil or plate material is exposed to different pressures on the two sides of the foil or plate. Device for superplastic forming a foil or plate for carrying out the method according to claim 1 the device comprising a table (10), a fastening means (11) for fixing the foil- or plate-shaped material (12) to the table (10) thereby defining a chamber (13) between the table (10) and the plate or foil and means (15) for creating a positive or negative fluid pressure on at least one of the sides of the foil or plate, characterized in that the device also comprises a laser source (16) for directing a laser beam (17) towards the foil or the plate in order to heat it up locally so that it is slowly deformed under the influence of the positive or negative pressure creating means. Device according to claim 4, characterized in that it is provided with a guiding system by means of which the laser beam can be directed towards the device according to a predetermined data program.

Inventors: NYRHILAE OLLI JOHANI, NYRHILAE, OLLI JOHANI, Nyrhilä, Olli Johani
Applicants: ELECTROLUX AB, AKTIEBOLAGET ELECTROLUX
Application year: 1995
Main classification: B21D26
IPC codes: B21D26, B23K26