Fuel injection rail manufacturing means and process

A manufacturing process for a single-block fuel injection rail of a type wherein said rail comprises at least one rectilinear hollow main tube (1) to which are joined rigidly at least one fuel intake tip (2);

• at least one and generally several injector intakes (3), and rail fastening means (4), the improvement comprising:
• heating an aluminium alloy billet (5) to a temperature in the range from about 430.degree. C. to about 460.degree. C. and, while in a heated condition, hot die forming in a die (6) made of two parts (6a, 6b), said hot die-forming comprising extruding said billet through an intermediate of said die (6) so as to provide said billet with a full primary shape (7) which corresponds to an outer shape of said rail to be made and which primary shape has one or several buckles (8) of an extruded aluminium alloy;
• cooling said primary form (7) to an ambient temperature level;
• cold machining said primary form (7), said cold machining comprising:
• cutting to an exact axial size required;
• removing at least one superfluous area (8b) of the extrusion buckles (8);
• retaining at least one functional area (8a) from said extension buckles in existence so as to obtain a secondary full form (9) corresponding partly to an outer form of the rail to be made;
• precision jigging said secondary form (9), including joining said secondary form (9) rigidly to a jigging assembly (10) such that the secondary form (9) is held firmly and in a precise position by jig (10) while outer ends (11) of the secondary form (9) remain accessible from the outside for drilling;
• cold drilling the secondary form (9) from the outer ends (11) in order to achieve, successively, drilling (a) of the main tube (1) and secondary drillings (2a, 3a) for the fuel intake and the injector intake such as to obtain a tertiary drilled form (13);
• cold-finishing machining said tertiary form (13) for forming fuel intake (2) junction tips and fastening means (4) for said rail;
• electrochemically deburring and cleaning said tertiary form;
• and
• optionally fitting a plug (14) rigidly to the outer end of said main tube by welding or by brazing.