Method for obtaining an opening in a hollow-body member, and a hollow-body member provided with one or more openings obtained with said method

#The present invention refers to a method for obtaining an opening in a hollow-body member, and to a hollow-body member having a longitudinal extension and provided with one or more openings obtained with the above-mentioned method; the hollow-body member can consist of a tube of cylindrical or polygonal cross section, and therefore open at one or both ends, of a fluid connector bolt, and therefore open at one end and closed by the bolt head at the opposite end, or to similar members. The openings obtained with the method hereof may be arranged both on an axis substantially transversal to the longitudinal extension of the hollow-body member and on an axial direction.

#A presently well-known method is to provide one or more openings in internally hollow cylindrical members by means of mechanical machining processes, generally milling, drilling o punching operations, which have the drawback of requiring subsequent restart operations to eliminate the cutting burrs that inevitably form during such operations, in particular on the inside walls of the cylindrical member due to the fact that the cutting direction is from outside toward the inside of such member. The subsequent restart and surface finishing operations are therefore rather difficult, as the tools are required to operate inside the cylindrical member. The requirement of making the edge of such openings as smooth and even as possible is dictated mainly by the need to avoid the possible subsequent detachment of metal particles which, if the hollow member is to be used in a pneumatic or hydraulic circuit, could damage other components in the circuit; in addition, still in the case of using the hollow-body member in the circulation of fluids, any discontinuities on the edge of the openings could hinder the smooth flow of the fluid, thus creating turbulence causing considerable pressure drop, or at least an irregular operation of the circuit.

#A well-known method also consists of forming openings on a cylindrical member through punching operations. One example of making openings by punching in an internally hollow cylindrical member is provided by the Italian Patent Application No. PN2008A000095 in the name of the present applicant, which refers to the production of a connector bolt for fluids, in particular oil, known in the art by the term “banjo”, provided with an internal fluid passage cavity and formed by known material deformation procedures, such as cold forging; the openings on the cylindrical wall through which the internal cavity communicates with the outside environment, or with a hydraulic circuit, are produced with a through punching process from the outside so as to cut out, in the punching area, a slug that spontaneously falls inside the cavity in the bolt.

#Additional characteristics and advantages of a method according to the present invention will become more evident from the following description of a particular, but not exclusive, embodiment illustrated purely by way of example but without limiting intents with reference to the following drawings, in which:

#FIG. 1 illustrates, in an axial cutaway view, a hollow-body member provided with one or more transversal openings obtained through a method according to the present invention applied, by way of example, to a connector for fluids;

#FIG. 2 shows, in a perspective view, the hollow-body member of FIG. 1, comprised by way of example of an internally hollow cylindrical bolt provided with one or more openings arranged transversally to the longitudinal axis;

#The following description refers partly, for convenience of disclosure, to the applicative example shown in FIG. 1, in which the hollow-body member is a bolt of cylindrical cross section, although it is understood that the method according to the present invention is generally applicable to obtain a hollow-body member that may consist of a tube of cylindrical or polygonal cross section, which may have cross sections of different diameters along its longitudinal extension, open at one or both ends and suitable for a range of different applications.

#With reference to the enclosed figures, numeral 1 refers to a connector for fluids including a support holder 2 on which is mounted a hollow-body member 3 consisting, in this specific case, of a bolt including a partially threaded body 4, a head 5 and a cavity 6 open toward the outside at one end 7 of the body 4; such a type of bolt is known in the oil-hydraulics field as “banjo bolt”. The connection between the bolt 3 and the holder 2 is by means of the threads on the body 4 that are screwed on an internal thread provided on the vessel 2.

#On the body 4 are created, through the method that will be better explained below, one or more through openings 8, 9 set transversal to the longitudinal extension of the bolt 3 and suitable for communicating the cavity 6 with the outside environment or with a fluid circulation duct.