Method for deforming a tube near one of its ends and tool used in this method

#The present invention relates to a method for deforming a tube near one of its ends, particularly for producing a sealed coupling for rigid tubes. The invention also relates to a tool used in such a method.

#The method at issue here needs to make it possible to deform a tube in order to produce a coupling of the type depicted in FIG. 2 of document DE-195 26 316 C2 or alternatively in document DE-197 57 946 A1. These two documents disclose a coupling of a rigid pipe. A nut is pressed on to the tube that is to be coupled. The end of the tube to be coupled is introduced into a male part of the coupling which, on the one hand, on its exterior surface, has a screw thread corresponding to the tapping of the nut and, on the other hand, on its inside, has a conical bore. The tube is deformed outward to produce a shoulder that makes it possible to limit the length over which the tube to be coupled can be introduced into the male part. Once the end of the tube has been pushed into the male part, the nut is screwed on to the corresponding screw thread, bearing directly or indirectly on the deformation of the rigid tube that is to be coupled.

#The cited documents do not indicate how the tube is deformed. It is in fact known practice for the end of the tube to be deformed to be placed in a die and for pressure to be exerted on the free end of the tube so as to deform its wall and for the material of which this tube is formed to be pushed into a housing provided for that purpose in the die.

#In any event, the invention will be well understood with the aid of the description which follows, with reference to the appended schematic drawing which, by way of nonlimiting examples depict a number of alternative forms of embodiment of a method according to the invention and a number of tools used in these alternative forms.

#FIGS. 1 to 4 schematically depict four steps in a method for deforming a tube near one of its ends, FIG. 5 is a view in section showing a coupling obtained from the deformation illustrated in FIGS. 1 to 4,

#FIG. 6 is a view corresponding to FIG. 4 for an identical method using a different tool,

#FIGS. 1 to 4 depict an openable die 2 with two jaws 4. Between these two jaws a tube 6 can be fitted. This tube is arranged in such a way that a free end thereof projects from the die 2. These figures also show a tool 8 having a front face 10 in which a cavity 12 is made.

#The tube 6 is a circular cylindrical metal tube. It has a longitudinal axis of symmetry 14.

#The die 2 is intended to hold the tube 6 while it is being deformed and also partly determines the shape of the deformed tube. The two jaws 4 that form the die 2 are pressed together by means which are not depicted and are known to those skilled in the art. Thus, they clamp and hold the tube 6 in place. A free end 16 of the tube 6 projects from the die 2. The tube 6 will be deformed in the region where the tube 6 emerges from the die 2.