The invention relates to a method for fitting a connecting ring of a cone connector used in hydraulic systems, said cone connector comprising a connector body, a tightening nut and a connecting ring with internal teeth to be fitted on a pipe to be connected by means of the cone connector. The invention also relates to a fitting tool to be used with a cone connector used in hydraulic systems, said cone connector comprising a connector body, a tightening nut and a connecting ring with internal teeth to be fitted on a pipe.

Cone connectors are widely used in hydraulic systems. Usually, cutting rings are used as connecting rings in cone connectors. International Standard ISO 8434-1 describes 24° cone connectors using cutting rings. Fig. 1 shows a cross section of a typical 24° cone connector having a body 1, a tightening nut 2 and a cutting ring 3 on a pipe 4. The cutting ring is pre-fitted on the pipe 4 by tightening the nut, creating axial movement towards the fitting body cone that forces the ring to bite into the pipe. The connection is completed by tightening the nut 2 with a certain torque, whereby the nut 2 and the pipe with a pre-fitted cutting ring move towards the body 1 and the outer cone of the cutting ring and the inner cone of the body 1 are brought into abutment to each other. This connection has been proven satisfactory per se, but it requires a skilled person to pre-fit the cutting ring correctly.

An aim of the present invention is to provide a novel solution for pre-fitting the connecting ring on the pipe to be connected by the cone connector. To this end, the method of the present invention is characterized in that the method comprises the steps of:

placing a connecting ring on the pipe near the pipe end;

placing a fitting tool over the connecting ring;

applying a radial force on the connecting ring by the fitting tool to crimp the connecting ring so that the teeth of the connecting ring bite into the pipe wall. The fitting tool of the present invention is characterized in that the fitting tool comprises a plurality of radially movable dies which together define a receiving space for the connecting ring, said dies being arranged to apply a radial force on the connecting ring to drive the teeth into the pipe wall by crimping the connecting ring.

The invention will be described further with reference to the following drawings, wherein:

Fig. 1 shows an example of a 24° cone connector in accordance with ISO

8434-1, Fig. 2 shows an embodiment of the cone connector of the invention, Fig. 3 shows an embodiment of a fitting tool of the invention, Fig. 4 shows a partial isometric view of the fitting tool of Fig. 3, and

Fig. 5 shows a part of the fitting tool placed on a pipe to press the

connecting ring teeth into the pipe wall.

As shown in Fig. 2, the cone connector of the invention comprises a connecting body 1, a tightening nut 2 and a connecting ring 3 placed on a pipe 4 near an end 7 of the pipe. The connecting ring 3 is pre-fitted on the pipe 4 by using a fitting tool 5 which will be described below. The fitting tool applies a radial force on the connecting ring 3 and the teeth 6 of the connecting ring bite into the pipe wall 8. The connection is completed by placing a seal 15 on the pipe 4 adjacent to the forward end of the connecting ring 3 and by thereafter tightening the nut 2 with a certain torque, whereby the nut 2 and the pipe 4 with the connecting ring 3 and the seal 15 move towards the connecting body 1 and the outer forward end cone of the connecting ring 3 and the inner receiving cone of the connecting body 1 are brought into abutment to each other, the seal 15 securing the connection against leakage. The connecting ring 3 is provided with a stopper surface 17 which is brought into abutment to an end surface 18 of the connecting body 1 in order to avoid excessive tightening of the seal 15 and to form a further metal-to-metal sealing which also supports the connection against vibrations and torsion. Figs. 3 and 4 show an embodiment of the fitting tool 5 of the invention. The fitting tool comprises radially movable dies 11 provided with connection nipples 16 for hydraulic or pneumatic driving media to move the dies radially inwards or outwards. The dies can be used in a conventional hose gripper. The dies 11 together form a receiving opening 17 for the pipe 4 and the connecting ring 3 thereon. Each die 11 has on its inner surface a receiving space 12 corresponding essentially to the contour of the connecting ring 3, but providing the necessary free space to allow the connecting ring 3 to dilate when compressing the ring 3 by pressing it radially towards the pipe wall 8.

The dies 11 are arranged to define a continuous ring 13 around the pipe end between the end surface 10 of the pipe 4 and the receiving space 12. Said continuous ring 13 has an inner diameter corresponding to or slightly larger than the outer diameter of the pipe 14, so that the pipe end is prevented from enlarging due to crimping forces. At least one of the dies 1 is provided with a stopper nose 9 in order to place the connecting ring 3 at a correct distance from the end surface 10 of the pipe 4. The dies 11 are further arranged to define a second continuous ring 14 around the pipe, axially behind the receiving space 12, as seen from the end surface 10 of the pipe 4. Said second ring 14 has an inner diameter corresponding to or slightly larger than the outer diameter of the pipe 4, said second ring 14 forming a stop to avoid excessive crimping.