A RADIAL PRESS FOR JOINING HIGH PRESSURE HYDRAULIC PIPES

FIELD OF THE INVENTION The present invention relates to a radial press for fastening connectors to flexible pipes used for hydraulic applications, in the air-condition systems, compressed-air distribution systems, or more in general anywhere the problem of fastening a metallic joint to a flexible pipe by joint plastic deformation occurs.

In particular, the press proposed by the present invention is used for joining pipes aimed at producing connectors for hydraulic organs, for example cylinders, engines and pumps onto machines . Within the scope of the previously mentioned uses, the present invention refers to a device, which is able to center the clamps of a radial press near the outer cylindrical surface of the joint, which is to be connected to the flexible pipe.

BACKGROUND OF THE INVENTION

As it is known, fluids, usually oil or air, often at high pressure, up to some hundreds bar, are carried along the oil or air conducting pipes, to operate the above mentioned devices .

Therefore, it is obvious that the conjunction between the joint and the pipe is critical, with reference to the safety as well as to the reliability of the machine.

The used joints include a sleeve, which is either cylindrical or has a slightly truncated cone shape, and which must be set

onto the end of the pipe and then pressed radially inward, thus becoming tightened to the outer surface of the pipe.

Thus, the radial presses used for compressing the joint include moving radial elements, supported and guided by a ring-like structure.

The elements have clamps at their end turned toward the center of the circumference defined by the ring-like structure; said center should always coincide with the axis of the pipe, onto which the joint is applied. Actually, one cannot be sure that this occurs operating the elements separately, and the compression on the sleeve does not allow to obtain a satisfactory union as much as tightness is concerned, as well as from the aesthetic point of view.

To obtain a uniform movement of the elements toward the center, and thus maintaining the clamps and the pipe always concentric, a one-cylinder moving system must be used.

The opposite head, with respect to the center, of each element is made inclined, so as to correspond to the inner inclined wall of a cup situated above or below the same elements .

A master cylinder pushes the cup toward the elements causing their movement toward the center .

Springs, arranged inside the guides of the ring-like structure, determine the elements return movement, when the cup is moved far from them.

In order to obtain a sufficiently wide movement of the elements, and of the clamps, it is necessary that the inclination of the elements head and of the cup inner wall be such as to determine a big movement of the elements with a small movement of the cup, that is of the operation cylinder.

Since the transversal dimension of the cylinder must be suitably limited, and due to the unfavorable effect of the inclination between the cup and the elements, the cylinder operation pressure must be particularly high. It results from what has been said previously that the dimensions and the weight of the so made press do not allow its easy transport, since the ring-like structure and the operation cylinder must be supported inside a frame, which increases its dimensions . ^' Moreover, the use of a heavy and bulky structure is little easy.

Further, the high pressure necessary for the cylinder operation requires the use of a suitable pump, which causes an additional increase of weight and dimensions. In case of manual operation of the hydraulic pump, the force the operator must apply is rather intense.

Therefore, when a pipe must be jointed, that is it must be provided with joint elements at its ends, or it must be repaired, an operation usually including the pipe total cutting and its rejoining by two joints, this pipe must be removed from the machine, on which it is mounted and then transported to a repair shop, where the press is placed firmly.

This is valid also for the air-condition systems or compressed air distribution systems, where the problem is actually amplified by the bigger pipe length and by the passages in the walls.

Obviously, all this it results in time and costs increase.

SUMMARY OP THE INVENTION

The object of the present invention is to propose a radial press for joining high pressure oil carrying pipes, in which the elements are operated directly, without the interposition of other means aimed at determining their synchronous movement, and first of all maintaining the clamps and the pipe centered during the joint sleeve compression.

Another object of the present invention is to obtain a radial press, in which the elements are operated directly, without synchronous movement means, maintaining the clamps and the pipe centered, by an original and inventive, but simple and cheap solution, which influences positively the press whole production costs .

Another object of the invention is also to obtain a radial press of limited dimensions and weight, which allows to transport it to the places, where the intervention must be performed, with obvious advantages resulting therefrom.

The above mentioned objects are obtained with a radial press for joining high pressure hydraulic pipes, including: a support ring-like structure; guiding means made radially in the ring-like structure; a plurality of elements, carried and guided radially by said ring-like structure and by said guiding means, so as to move radially with respect to the ring-like structure; operating means for driving said elements; said radial press being characterized in that: said operating means act directly and independently on the respective elements, to cause their movement toward the center of said ring-like structure; it includes stop means, activated elastically for stopping all the elements in a position, in which they are concentric,

with innermost ends being close to a joint situated at the end of a pipe (40) and introduced in the radial press, said stop means allowing the elements to continue toward the center of the ring-like structure, as a consequence of overcoming the constraint imposed by said stop means .

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristic features of the invention, not resulting from what has been said previously, will be explained in the following description with reference to the enclosed figures, in which:

Figure 1 is a schematic view of the radial press proposed by the present invention, with one part removed, so as to better show the inner parts;

Figures 2A, 2B and 2C show three characteristic positions of the parts of the press in its operation;

Figure 3 is a section view, taken along the plane III- III of Figure 2A, of a detail of the press; - Figures 4 and 5 are schematic views of two constructive embodiments of the press.

BEST MODES QF CARRYING OUT THE INVENTION Having regard to the above Figures, numeral reference 1 indicates a radial press for joining high pressure hydraulic pipes, such as ones used for actuating operating means on machines .

Although, later on the reference is made to this particular application, the invention refers also to the joining of flexible pipes for air-condition systems, compressed air distribution systems and any other application with similar characteristics.

As the base element, the press includes a ring-like structure 20, acting as a support for all other components.

Guiding means 4, oriented radially, are made in the structure. A plurality of elements 2 are supported by the ring-like structure 20 and guided by the guiding means 4, so as to move radially with respect to the ring-like structure, thus toward the center of the latter and in the opposite direction outwards . Operating means 8 are associated to the ring-like structure to operate the elements 2, moving them forcedly toward the center of the ring-like structure 20.

Springs 12 are fastened to the ring-like structure 20 and act in known way on the elements 2 for their return outwards . According to a preferred embodiment, the support ring-like structure 20 includes a doughnut-shaped body, which for example has a circular perimeter, as seen in Figures 1 and 4.

According to a possible variant, the outer perimeter of the ring-like structure can be polygonal, e.g. octagonal, as seen in Figure 5.

This allows to obtain on the outside a series of flat surfaces 25, which results in obvious structural advantages and improvement of the manipulation of the pieces to be subjected to different processing operations. Other advantages of the polygonal perimeter will result evident later on.

The guiding means 4 include radial holes, whose cross-section corresponds to the cross-section of the elements 2.

Actually, .the radial holes 4 can couple with the elements partially, for example including two adjacent portions 41, 43, whose cross-sections have different dimensions.

As seen if Figures, ^' .the innermost portion 41 of the radial holes 4 has a cross-section e.g. oval, which prevents rotation of the elements 2, likewise of oval cross-section.

The outermost portion 43 of the radial holes 4 in the doughnut-shaped body has the cross-section of equal or bigger diameter with respect to the biggest dimension of the oval portion, as shown in Figure 3, which shows a section view taken along the plane III-III of Figure 2A.

According to the embodiment shown in Figure 1 the radial holes remain open outwards and house a plurality of pistons 10, which form the operating means 8.

All in all, there is one piston 10 for each element, and not only one hydraulic cylinder, which operates all the elements together by coupling of conic surfaces, as in prior art. The pistons 10 can be joined to the elements 2, or made integral therewith.

The return springs 12 push against the piston innermost surface.

Otherwise, according to a not shown embodiment, the piston 10 can be operated in double-acting mode, pushing the oil into one chamber and withdrawing it from the other at the same time .

Moreover, this embodiment, which requires a gasket also on the element 2, is advantageous because it eliminates the return springs 12, and also permits to modulate, by suitably

situated narrowings, the movements of the piston, and thus of the element.

A band 15, likewise ring-like, is applied around the doughnut-shaped body of the ring-like structure 20, joined to the body by screws with interposition of seals.

In this way a chamber around the doughnut-shaped body is created, into which oil under pressure can be introduced by a screw connector 37 connected in known way to a pump 38, for example operated manually. Obviously, the manual pump can be substituted by a power- operated pump or by a hydro-pneumatic pump.

Although all the pistons 10 are subjected to the pushing action of the pressurized oil in the same chamber, they are operated directly and independently one from another. The pipe 40 with the joint 50 put thereon is placed on the central part of the press 1, being introduced into the hole of the doughnut-shaped body.

Therefore, acting on the pump determines the forward movement of the pistons 10, and thus of the elements 2, toward the center.

According to the invention, stop means 30, formed by elastically preloaded catch members, are aimed at being introduced into cavities 35 made on the elements, in order to prevent one or more elements from pushing against the joint sleeve 50 before the others.

More precisely, the catch members are small spheres 31, situated inside the threaded holes 22 made in the support ring-like structure.

The holes 22 are situated in positions corresponding to respective radial holes 4, in particular in the region of the oval cross-section of smaller dimension.

The small spheres 31 are preloaded by springs 33, acted on by threaded dowels -32, screwed into the threaded holes 22.

In order to obtain a more compact structure of easy assembly, the springs 33 and the spheres can be situated inside the dowels, in known way.

This component, already configured in this way, is accessible on the market .

In this way, all the elements move independently (Figure 2A) until they reach the point, in which the spheres are introduced into the cavities 35 (position S of Figure 2B) stopping the elements.

According to an interesting embodiment, not shown, the stop means can include an angle-shaped foil, fastened in known way at the inner edge of the doughnut-shaped body, above the respective element.

The free end of each foil has a protrusion turned toward the element 2 and being introduced, when the elements are operated, into the cavity 35, more toward the center of the doughnut-shaped body, stopping temporarily the element movement .

At this point, in both cases, the inner ends 21 of the elements 2, on which can be applied the so-called clamps 26, having the shape and the constructive characteristics suitable to their function, are all arranged concentric with respect to the ring-like structure 20, along a circumference near to the outer surface of the joint 50 (Figure 2B) .

Only when the force applied by the oil to the pistons overcomes the constraint opposed by the spheres , do the elements continue their run against the joint 50 to complete the compression of the sleeve on the sleeve 40.

However, the clamps 26 push now contemporarily against the sleeve (Figure 2C) and maintain the movement synchrony until the operation is completed.

According to an embodiment, shown in Figure 4, there is no outer band, but the initial part of the outer part 43 of the radial holes 4 is threaded and the holes are closed by screw plugs 17, with interposition of suitable seals.

Thus, the holes 4 with the plugs 17 define a series of chambers 16, inside which the pistons 10 slide and which are connected by inner channels 19.

All the cited pistons 10 are operated by the introduction of pressurized oil in only one chamber.

According to the variant of Figure 5, the plugs 18 have widened heads 24, which go in abutment against the flat surfaces 25 of the ring-like structure 20 of polygonal perimeter .

Also in this case, the introduction of oil in only one chamber operates all the pistons 10.

In all the above described embodiments, the radial press proposed by the present invention is produced according to a constructive configuration, which is simpler than the known ones, by virtue of the presence of the small spheres 31, preloaded by the springs 33 and pushed into the cavities 35 of the elements, so as to stop the latter temporarily, which results in their alignment in the just-before-pressing position S.

Actually, this contrivance allows to neglect the free and not uniform movements of the elements during the initial step of the fastening of the joint 50 to the pipe 40. The necessary symmetry is resumed automatically in the position S, and when the force acting on the elements 2,

almost touching the joint sleeve with the respective clamps, pushes them to overcome the constraint opposed by the spheres, the symmetry is maintained.

Another advantage lies in fact that the pressure necessary to operate the pistons 10, and consequently the elements 2, decreases with respect to the presses operated by only one piston.

This is obtained by the bigger total surface, created by more pistons with respect to only one piston, which allows to generate a bigger deformation force with the same pressure, that is to apply the same force with a lower oil pressure.

Thus, also the operation pump is reduced, decreasing the device weight and dimensions, as well as the force -necessary for its operation by the operator (or of the hydro-pneumatic pump) .

Consequently, what above results in a simple, light and thus easily transportable structure, which allows to carry out the interventions where necessary, without disassembling the pipe and bringing it to the machine repair shop. Also the production costs are positively influenced. And all this maintaining high quality of the performed operation.

Experimental tests have proved that one obtains a fastening of the joint with a uniform ^' deformation of the sleeve, which consequently assures the reliability as much as tightness is concerned, as well as the joint safety.

The last point is particularly important, because of high pressure, at which the hydraulic pipes must operate.

Obviously, according to known techniques, the clamps 26 can be substituted with the ones each time more appropriate for the pipe and the joint to be fastened thereto.

It is understood that variants or changes of the invention which improve or integrate the described embodiments, are within the protective scope defined by the following claims, interpreted in the light of the previous description.