ZA200400153B - Metal ring assembly which is assembled and soldered to a support collar in order to form the annular cooling conduit of an internal combustion engine piston, the method of producing said finned metal ring and the metal ring thus obtained. - Google Patents

Description

TRADUCCION AL INGLES

Solicitud PCT ES 02/00365

Titular: Roberto Oscar App6

Fecha 18-07-2002

N/ref: P-1187

A MOUNTING OF A METAL SHEET RING ASSEMBLED AND WELDED IN A

CARRIER HOOP, TO CONFORM THE ANNULAR COOLING TUBE OF A PISTON

OF INTERNAL COMBUSTION ENGINE, METHOD TO MANUFACTURE A FIN

METAL SHEET RING AND THE METAL SHEET RING BEING OBTAINED

The main object of the present invention is a mounting of a metal sheet ring assembled and welded in a carrier hoop, to conform the annular cooling tube of a piston of internal combustion engine, the method to manufacture said fin metal sheet ring and the metal sheet ring being obtained which, as regards the specific conditions of mounting herein established, achieves greater security in the cooling tube imperviousness.

More particularly, this invention contemplates a mounting of metal sheet ring assembled and welded to a carrier hoop, capable to be engaged to the pistons of the internal combustion engines conforming a cooling internal tube, usually called cooling gallery.

This invention refers to a manufacturing method specially created to conform a fin metal sheet ring of such a type that, once assembled and welded to a carrier hoop, is coupled to the body of a piston of the internal combustion engine forming an internal cooling tube, also called cooling gallery.

As it is well known, the pistons used in the internal combustion engines, particularly in diesel engines, are subject to extreme thermal conditions and great mechanical strengths, thereby requiring long durability under severe conditions, as they are subject to important loads due to the pressure of the combustion impact and the heat being . generated.

That’s why various pistons designs are already known including the existence of a cooling internal tube which is generally located adjacent to the annular piping housing the top hoop of the piston; thereby, a cooling liquid, generally oil, circulates through said internal tube for the purpose of counteracting the action of the extreme temperatures that the piston and the hoops thereof are being exposed. In order for this action to be effective, it is required that the cooling path should be the nearest possible to the piping housing the compression hoops.

Indeed, said extreme thermal conditions and mechanical solicitudes, make certain parts of the piston to be subject to special strengths that, due to the above mentioned reasons, may suffer damage or faults. The cooling of the most affected zones or paths, made it possible the creation of the above mentioned cooling internal tubes that configure the cooling internal galleries through which cooling oil may circulate.

Several techniques for the manufacturing of these cooling tubes have occurred, wherein different types of structures and designs are determined, said tubes being generally annular and being able to communicate with other tubes extending towards the inside space of the piston body.

The mounting of the present invention is applicable to an aluminum alloy piston for internal combustion engines, one of the type having a top circular head (piston head) and a cylindrical wall extending downwards from said head. In this case, such head, also includes the metal insert defining the annular cooling tube, arranged within the head, constituted by a carrier hoop radially extending, coaxial to the shaft of the piston body and supporting a cross sectional metal sheet ring similar to a “U” or equivalent, assembled and welded to said carrier hoop.

This invention introduces the novelty that specifically refers to the witty resource of mounting being used for the attachment and coupling of the metal sheet ring on the carrier hoop, said mounting makes sure the ring to be kept duly positioned and fixed on the carrier hoop before the welding is carried out, not being required the use of stress due to differences of thermal expansion and providing a convenient support to the welding bead.

The great advantage of the inventive mounting, is the low cost of the coupling and the great efficacy and security being achieved, above all, for the application of the continue welding bead, thereby establishing the close binding of both component parts.

Normally, the piston body is of an aluminum constitution and is molding manufactured, such that, the referred cooling tube is an insert that is located into the constitution die, previous to the tapping, to be arranged within the piston body. This insert comprises a carrier hoop that is usually cast iron with nickel and copper and the metal sheet ring of cross section such as a “U” wherein the free ends of its fins are arranged welded to said carrier hoop. Under these circumstances, the piston integrity and its structure are kept.

Accordingly, an internal annular tube is introduced, which walls are constituted by the referred metal sheet ring in “U-shaped or its equivalent and the inside radial surface of the carrier hoop, being previously bound to each other by welding. An effective union is intended to be established such that it makes sure the non-entrance of material to the inside of the cooling tube during the aluminum tapping being carried out in the process of molding manufacturing of the piston.

In order to achieve an effective union between the metal sheet ring and the carrier hoop, it is important for the sealing welding to be hermetic and secure to avoid the entrance of aluminum to the inside of the tube, as well as the exit of hot gas from the inside to the liquid aluminum being poured during the tapping process.

In order to be sure that this welding is hermetic, it is highly important that the metal sheet ring is coupled to its respective carrier hoop without carrying stress that may affect such welding. Thus it is highly important to create metal sheet rings having dimensions a. 4 extremely precise and with a final constitution that will not carry stress to the carrier hoop during the welding process.

It is contemplated that there exist several format and design options for these annular cooling tubes, said options should be in accordance the final use the piston containing the cooling tube will have. Many of these several designs get real by means of the variations in the format of the fin metal sheet ring.

This invention specifically refers to a new method for the manufacturing of these fin metal sheet ring, wherein the referred options of design variation of the final format are also included.

PRIOR ART

As it was previously noted, several inserts applied to the pistons, are already known, in order to provide the mentioned annular cooling tube. Special manufacturing methods have also been disclosed to justify the requirements of security and resistance capacity.

To this effect, the following patents may be cited as an example: US Patent N° 4.776.075, N° 4.586.553; or N° 3.991.811, all of which disclose respective designs of pistons with internal annular cooling galleries.

The Applicant also mentions the US Patent N° 5.903.974 referring to a method and apparatus to produce grooved hollow insert hoops for engine pistons, said hoop is arranged near the top or piston head so as to constitute an internal piping for a cooling passage adjacent to the hoop slot. Therefore, a structure is formed including a metal sheet ring which cross section takes a “U” shape and a molded carrier hoop. The molded carrier hoop is made of a high resistance material and, preferably of the same thermal expansion coefficient as the piston body. Both elements are bound by a welding bead, said bead fixes the outside part of the “U” section ring and the inside radial surface of said carrier hoop.

Accordingly, the tube being adjusted for the cooling liquid circulation is defined by said inside radial surface of the carrier hoop and the one of the metal sheet ring of “U” section.

The disadvantage, in this case, is particularly the precision required for the mutual } coupling of said two pieces that conform the correct adjustment of the cooling tube such that, when using, no undesirable cracks occur due to relative movements of these elements bound by the welding bead.

Indeed, patent N° 5.903.974 establishes that the internal diameter of the carrier hoop should be slightly less than the diameter of the free ends of the “U” branches of the metal sheet ring being assembled. To establish the union, the carrier hoop should be previously heated causing the internal diameter to expand, such that, in this way, said sheet of “U” section makes pressure and keeps itself duly positioned during the welding work.

This welding, which has neither a base nor a backing, is very difficult to be carried out. It is only possible by means of sophisticated methods that are of a very high operative cost.

Furthermore, the paths being assembled, should be mechanized with very low tolerances such that, in any case, the interferences that should take place, are always kept.

That is to say, the thermal expansion is used to get the desired and stable positioning of the pieces to be bound, which in turn, besides being of high cost, if such binding of pieces is not carried out properly, it takes the risk that tensions, taking place during the use of the piston, may cause undesirable cracks.

Apart from the above mentioned, it is contemplated that this construction only makes possible the constitution of cooling tubes limited to a “U” cross section pattern of parallel faces, which is highly restrictive as, there exist many pistons designs of other section formats according to the various requirements.

The main problem for all these embodiments consists of achieving a very good assembly and positioning of the “U” section metal sheet on the inside surface of the carrier hoop, this being rather difficult and generally of a high cost, above all for the previous tasks of assembly, positioning and also welding that have to be carried out.

It is specially mentioned that in this mounting, no backing fitting for the welding bead that determines the union of both components, is required, said process being difficult } to be carried out and insecure as regards the air tightness being required.

Different patent documents make approaches on this matter, one of them is the patent DE 26 24 412 that discloses that a metal sheet in a flat circular crown shape, is placed on the annular cavities that the carrier hoop presents to this effect. The metal sheet is folded over the hoop and adjusted therein with a proper tool. Then, the sealing of the union is carried out by applying welding to the contact edges.

The disadvantage or inconvenient of this mounting is that the adjustment of the folding is limited by the body itself of the carrier hoop that prevents the metal sheet from being firmly adjusted before the welding.

It is not possible to assure that the metal sheet will be properly assembled at the desired position, making adequate pressure against the body of said carrier hoop, before the welding process.

US Patent N° 6.105.540 is also mentioned as part of the prior art and discloses a cooling annular mounting applicable to an internal combustion engine, that comprises a cooling tube conformed by a metal sheet welded to a supporting carrier hoop.

The novelty introduced by this US patent is that, in this case the metal sheet having a “U” section keeps itself pressing on the inside annular surface of the carrier hoop and is not contracted by the temperature differences between the hoop and the cooling tube. That is to say, it takes advantage on the previous embodiments as expansion differences are not being taken into account for the mounting of the metallic hoop in the carrier ring.

The object of this US Patent N° 6.105.540 is to provide an insert for the adjustment of the cooling tube to make sure an adequate positioning of the metallic hoop on the carrier ring before the welding process, such that a firm and secure welding joint is established between the carrier hoop and the metal sheet ring.

Said invention contemplates that the precise and stable assembly should be made by using tools applying temperature on the metal sheet ring, though mentioning that the application of temperature differences may be omitted. . The basic idea disclosed and covered by this US patent N° 6.105.540 is to use the properties of “certain elasticity” of the metal sheets to help their positioning in the carrier hoop, keeping themselves with certain pressure against the inside radial surface of the hoop such that the welding process may be properly carried out.

It is thereby established as a condition that the angle between the inside surface/s of the carrier hoop and the branches of the “U” of the metal sheet ring should be less than 45°, due to the fact that if this measurement is exceeded, the mounting will not be benefited by the referred “elasticity”.

Though, as from this constructive principle of mounting, advantages occur as compared to what previously known, by analyzing it in itself, some disadvantages may appear that are clearly overcome with the mounting of the present invention.

Indeed, it is contemplated that for the mounting disclosed by US patent N° 6.105.540, it is required that the “U” profile being formed with the metal sheet ring should be symmetric as, otherwise, the pressure over the inside surface of the carrier hoop will avoid a correct positioning.

It is also contemplated as a limit to this background the condition that, the walls of the channel defining the metal sheet ring should always keep a compressive stress. If this condition is not met before and during the welding process, such process may be affected.

Again, it is contemplated the limitation establishing the condition that both fins of the “U” profile of the metal sheet ring should constitute an angle less than 45°, with respect to the plane of the inside surface of the carrier hoop supporting them.

It is also noted such limitation about that the inside surface/s of the carrier hoop should not generate a truncated cone seat for the ends of the fins of the “U” profile that conforms the metal sheet ring.

It is specially noted that the carrier hoop should not present pairs of inside radial surfaces defining seat steps for the free ends of the fins of the metal sheet “U” profile due ) to the fact that the difference of the diameters between the free ends of said fins and the ] inside surfaces of the support hoop should be at a minimum. If said steps are not present, the welding of the fins is carried out without support, which is not certainly secure.

It is specially noted that whenever an assembly is carried out as the one achieved with the mounting disclosed by patent N°6.105.540, the welding bead that fixes said assembly will not have a stable backing as the supports of the free ends of the fins of the “U” profile of the metal sheet ring have a reduced surface, in this case a welding may be carried out only with a great material supply.

Accordingly, any alteration to the established compressive stress, that may be caused by the temperature variation, affects directly the welding bead.

According to this prior art, there exists some background that disclose processes for the manufacturing of these metal sheet rings.

Japanese Patent JP-A-5-231539 is a background of this art, said patent discloses a structure including a metal sheet ring of a cross section in “U”-shaped and a molded support hoop, that are coupled by the welding of the ends of the metal sheet ring and the inside part of the support hoop.

This document discloses that the metal sheet ring is created by rotating the metal sheet having the same thermal expansion coefficient of the material of the piston body.

Indeed, as it is also disclosed by US Patent No. 5.903.974 to Kenji Nakajima, these metal sheet rings of a “U” cross section that has up to now been manufactured from stainless steel sheets of 18 mm width, 290 mm length and 0.6 mm thickness for example, which are curved using roll manufacturing machines. Once curved, said sheet is placed on a template of circular cross section and welded in its free ends to constitute a circular ring.

By means of these rotating manufacturing machines, this ring acquires a “U” cross section.

As a complement to what previously disclosed, the Japanese patent application JP-

A-6-210383 states: A cylindrical sheet, obtained by welding the free ends of curved sheet,

is winded in a roll manufacturing machine to adopt the format of a circular collar of “U” section. Then, said collar is arranged in a rotating machine getting the predetermined } dimension according to the inside diameter of the hoop. In a further step, the sheet having a ring-shaped passes through a machine that will remove the roughness from the edges of the circular collars ends that were formed during this process.

US Patent N° 5.903.974 also discloses that, as a conventional technique for the manufacturing of these sheet metal rings the use of three different machines: a roll, a rotating device and a cutting down device (a polishing device for the purpose of removing surface roughness or irregularities). These machines are not assembled but should rather be placed one after the other one occupying a big space. This represents a high cost of installation. Nakajima states that with the conventional technique no metal sheet rings can be effectively produced.

The novelty disclosed by US Patent 5.903.974, is a machine to produce these metal sheet rings that includes the steps to place a cylindrical hoop into a receiver slot, such that while the die rotates with the cylindrical hoop being in a movable position, a roll makes pressure on said hoop forming the collars that confers the “U” section format to the hoop.

Then each ring, so preformed, is arranged such that a cutting machine acts over the free edges, while the die supporting it rotates, making the edge smooth, that is removing the folds and the rough edges that may exist.

It is also contemplated that it is a machine or process specially designed to make rings of “U” profile with straight fins. In case another profile design or cross section is required, other construction die specially designed for each case, should be introduced, thus considerably increasing the manufacturing costs.

It is also contemplated that in each case, it refers to processes that combines rotating dies with pressure roll, that change a cylindrical ring into a ring of “U” profile.

It is also contemplated that all these specifications refer to cylindrical rings constituted from curved sheets that are then welded by their free ends.

INVENTION NOVELTY - MAIN OBJECT . As it was previously mentioned, the mounting referred to herein is applicable to an aluminum alloy piston for internal combustion engines, of the type having a top circular head (piston head) and a cylindrical wall extending downwards from said head. In this case, said head also includes the metal insert defining the annular cooling tube, arranged within the head, constituted by a carrier hoop radially extending, coaxial to the shaft of the piston body and supporting a metal sheet ring of cross section similar to a “U”, assembled and welded to said carrier hoop.

The novelty introduced by this invention, specifically refers to the witty resource of mounting that is used for the binding and assembly of the metal sheet ring on the carrier hoop, said assembly makes sure the ring to be kept duly positioned and fixed on the carrier hoop before the welding is carried out, not being required the use of stress due to differences of thermal expansion and providing a highly convenient and secure backing to the welding bead.

The first novelty that makes this embodiment standing out from all those that are presently already known is that the carrier hoop provides, for the seat of each of the paths of annular edge of the metal sheet ring, a surface support that is defined in a diametrical plane and also a surface support being defined in an axial plane. Both surfaces of support, are inside surfaces of the carrier hoop that constitute an angle to each other, being their diameters superior to the diameter of the inside surface of the same hoop defining between both of them.

As from this constructive principle, the invention contemplates that the referred seats may present an oblique orientation for those cases wherein the required metal sheet ring has the fins constituting a truncated cone (without restriction of angle setting).

Accordingly, these surfaces, defining said seats of the metal sheet ring, are arranged separated of each other, by a path extending towards the inside space of the hoop, thus constituting one of the inside surfaces of the cooling tube being conformed.

As from the above mentioned, it is clear that a double support seat is created to } benefit the support to the welding bead, being a part thereof.

This advantage is possible due to the novelty constructive solution established for the mounting of the metal sheet ring on the carrier hoop. Indeed, in order to carry out the adequate and stable mounting, the ring is presented and positioned in the carrier hoop body without its final format.

A preformed ring is created wherein one of the fins of its “U” cross section is open at an angle larger than the other one. Under these circumstances, the diameter of the free end of one of the fins is, at least, similar to the diameter of the inside surface of the carrier hoop where said fin stops; while the diameter of the free end of the other fin, is substantially less than the diameter of the inside surface of the carrier hoop where said fin stops.

Under these circumstances, when the preformed ring is positioned, one of the fins thereof will be arranged in its seat place, while the other one will keep slightly separated of its seat having a minor diameter. By using an adequate tool, a compression action will be made over the ring to take said fin open, up to the time said fin locates at the corresponding seat of the carrier hoop and stops.

Tests already carried out show that, as mentioned, this mounting is highly effective as the metal sheet ring keeps positioned, without stress and stable such that the welding process may be carried out. An ideal positioning is achieved without generating thermal expansions and no undesirable stress is caused when coupling. It is a clearly mechanical assembly.

It is particularly noted that this inventive mounting allows that the profile or cross section of the metal sheet ring may respond to different designs and dimensions, due to the fact that by introducing the constructive condition of generating the ring preform, in the above mentioned way, to allow the coupling to the carrier hoop, it will always be possible oo 12 to carry out the mounting under desirable conditions for the further and final welding ’ process.

Accordingly, it is contemplated that this inventive mounting allows the mounting of metal sheet rings of “U” section or equivalent, wherein the fins of the “U” form an acute angle with the cross web binding them; they are convergent fins.

It is also noted that this invention allows the mounting of metal sheet rings where one of the fins is longer than the other one, in such a way, that the width of the cooling tube being conformed, is greater than the height or thickness of the carrier hoop.

It is also noted that, as a consequence of the inventive mounting, the seats being defined by the carrier hoop to support the free ends of the fins may be parallel or oblique to the horizontal plane of the assembly, that is to say, truncated cone seats.

It is also noted that, as a consequence of the inventive mounting, “U” section metal sheets or equivalents are possible to be defined, having the fins thereof different curvature degrees with different ratios and angles.

It is also noted that, as a consequence of the inventive mounting, “U” section metal sheets or equivalents may be designed, such design determines that the cooling tube should be arranged disaligned with respect to the symmetry axis of the carrier hoop.

It is also contemplated that the double support of the sheet fins, constitute a highly secure backing to any type of welding with or without a third material supply.

Accordingly, the main object of the present invention may be defined as follows:

AN MOUNTING OF METAL SHEET RING ASSEMBLED AND WELDED ON A

CARRIER HOOP TO CONFORM THE ANNULAR COOLING TUBE OF A PISTON

OF AN INTERNAL COMBUSTION ENGINE, wherein the mounting consists of a metal sheet ring, which cross section comprises a web extending between two fins projecting towards the carrier hoop such that, the free ends thereof rest and couple to the annular seats being defined in the inside face of the carrier hoop, matching their curbs of internal edge: where said support and coupling are sealed by respective annular welding beads extending along the mentioned annular seats and rest in the carrier hoop body, being conformed an inside annular cooling tube which inside surface is constituted by a metal sheet ring and : the inside diametrical surface of the carrier hoop extending between said two annular seats.

The invention contemplates that the fins of the metal sheet ring should be oriented in convergent direction towards the carrier hoop.

It is also contemplated that the fins of the metal sheet ring should be oriented perpendicular to the carrier hoop.

It is also contemplated that the body of the carrier hoop should be of a truncated cone cross section and the fins of the metal sheet ring should be oriented in convergent directions towards the respective annular seats of the carrier hoop.

It is also contemplated that one of the fins of the metal sheet should be oriented in perpendicular direction to the carrier hoop body and the other one follows a curved line and then reaches a final straight path extending up to the seat, which is in cross sectional direction to the carrier hoop.

It is furthermore contemplated that both fins of the metal sheet are curved with the end paths thereof oriented in cross sectional direction towards the carrier hoop.

On the other side, it is contemplated that the height of the metal sheet ring may be higher than the height of the carrier hoop.

It is also contemplated that the annular welding beads that rest on the carrier hoop are defined on the annular seats of said hoop, confined in a double backing support.

Furthermore, for the coupling of the metal sheet ring into the carrier hoop, said ring previously presents one of its fins tear down having an angle greater than the other one, in such a way that the diameter of its free end is less than the diameter of the free end of the other fin, while, after the coupling this tear down fin is pressed against the carrier hoop body adopting its final position and format.

It is also contemplated that for the coupling of the metal sheet ring into the carrier hoop, the diameter of the free end of one of the fins, is less than the internal diameter of the carrier hoop.

Furthermore, the method to manufacture the fin metal sheet ring referred to herein, } is clearly distinguished from all the others currently known as no expensive machines are required due to the fact that said ring is constituted by using known and conventional dies and tools.

It is whereby eliminated the need of using means to produce the rotation of the piece being conforming, together with conformed rolls, thus requiring high costs on machineries, fittings and labor.

It is hereby eliminated the need of cylindrical rings constituted by curved sheets having ends attached by welding. By avoiding the welding, possible damages or faults due to a bad welding is also avoided.

To constitute the inventive ring, a flat metal sheet commercially available in the market is used.

This brings the advantage of selecting, without any inconvenient, different thickness degrees of the sheet with respect to the desirable thickness to form the wall of channel “C”.

It will also be possible to select different type of materials, as for example different qualities of stainless steel and/or carbon steels.

The inventive process allows to adjust the profile design of the ring with respect to the need to establish the final design of the cooling channel being conformed.

No previous welding is required for the ring manufacturing, thus eliminating, from the beginning the possibility of welding faults.

It is contemplated that this is a fully novel performance, as a stamping method from a flat metal sheet, preferably circular, is used.

Accordingly, the main object of the present invention is a METHOD TO

MANUFACTURE A FIN METAL SHEET RING CAPABLE TO BE COUPLED TO A

CARRIER HOOP AND CONFORM THE ANNULAR COOLING TUBE OF A PISTON

OF AN INTERNAL COMBUSTION ENGINE, that comprises the following steps: take a flat metal sheet of a desired thickness, and cut it creating a circular disk; produce, by stamping on said disk, a circumferential wall having a folded edge of diverging fin; cut and remove the circular bottom, by stamping the piece being constituted in the previous step; take the ring constituted in the previous step and form a second folded edge of diverging fin by stamping the circular edge opposite to the one already existing in the first diverging fin; place the fin ring produced in the previous step in a rotating support and submit said ring to a final calibration by means of cutting tools that act on the circumferential edges of both fins.

It is also contemplated that, the stamping dies comprise a support piece and a stamping tool wherein the cooperating active surfaces, that lock the metal piece being acted on, present peripheral paths having structures that respond to the foreseen design for the metal sheet ring being formed.

It should be noted that the cutting action produced on the metal sheet in the first step, is carried out by a circular cut-die by stamping.

The present invention refers to, as a secondary object, A FIN RING OF METAL

SHEET, obtained by means of the described method and consists of a sole body of metal sheet, which cross section is a “C” profile having diverging fins that respond to different pre-established designs.

It is also noted that the different pre-established designs for the diverging fins of the metal sheet ring may have different orientations, curvatures and dimensions thereof.

BRIEF DESCRIPTION OF THE FIGURES

In order to complete the above mentioned advantages, it will be apparent for users and those skilled in the art that many other ones may be added in order to facilitate the understanding of the constructive, constitutive and functional features of the inventive mounting, a preferred example of embodiment is described below, which is schematically h 16 illustrated with no specified scale, in the enclosed figures, clearly stating that, just for being an example, it doesn’t intend to limit the scope of the present invention, but only to : help as an illustration of the basic principles thereof.

Figure N°1 is a partial lateral view complemented by a vertical section of the body constituting a piston of the internal combustion engine.

Figure N°2 is a cross sectional view representing the inventive mounting, showing the case wherein the fins of the metal sheet ring of “U” section are straight and parallel to each other.

Figure N°3 is a cross sectional view representing the inventive mounting, showing the case wherein the fins of the metal sheet ring of “U” section are convergent.

Figure N°4 is a cross sectional view representing the inventive mounting, showing the case wherein the body of the carrier hoop presents obliquely oriented seats (truncated cone construction) due to the fact that the fins of the metal sheet ring are convergent towards said seats.

Figure NOS is a cross sectional view representing the inventive mounting, showing the case wherein the cooling tube conforming the metal sheet ring is of a height greater than the height of the body of the carrier hoop. Said tube is arranged disaligned with respect to the symmetry axis of the carrier hoop.

Figure N° is a cross sectional view representing the inventive mounting, showing the case wherein the fins of the metal sheet ring are curved.

Figure N°7 is a vertical section scheme, showing the metal sheet ring of “U” profile and parallel fins as it is represented in figure N°2, in this case preformed for its positioning into the carrier hoop, before the final assembly, being the diameters of the free ends of the fins different to each other.

Figure N°8 is a vertical section scheme, similar to the one of the previous figure, representing a profile of the metal sheet ring as it is represented in figure N°3, in this case preformed for its positioning into the carrier hoop, before the final assembly, being the diameters of the free ends of the fins different to each other. ) Figure N°9 is a vertical section scheme, similar to the one of the previous figures, showing the case wherein the seats of the carrier body are oblique and oriented in diverging direction and a metal sheet ring such as the one represented in Figure N°4, is arranged preformed for its positioning into the carrier hoop, being the diameters of the free ends of the fins different to each other.

Figure N°10 is a vertical section scheme, similar to the one of the previous figures, showing a metal sheet ring such as the one represented in Figure N°5, in this case preformed for its positioning into the carrier hoop, being the diameters of the free ends of the fins different to each other.

Figure N°11 is a vertical section scheme, similar to the one of the previous figures, showing a metal sheet ring of “alveolar” profile (continue curve) such as the one represented in Figure N°6, in this case preformed for its positioning into the carrier hoop, being the diameters of the free ends of the fins different to each other.

Figure N°12 is a vertical section scheme showing the way the final positioning of the pieces constituting the cooling tube is carried out, being mounted according to the present invention.

Figure N°13 is a vertical section scheme showing the way the welding process on the already positioned pieces is carried out.

Figure N°14 is an enlarged detail, in vertical section showing the carrying out of the coupling of the edge of free end of a fin of the metal sheet ring on the corresponding assembly seat defining the carrier hoop, so that the welding process may be carried out.

Figure N°15 is an enlarged detail, in vertical section, similar to the one of the previous figure, in this case showing the constitution of the annular welding bead binding both pieces in a fixed and secure way.

Figure N° 16 is a perspective view showing a fin metal sheet ring that may be conformed by the method herein.

Figure N°17 is a side view, complemented by a vertical section of the body that constitutes the piston of an internal combustion engine.

Figure N°18 is a cross sectional detail showing the insert being introduced to the piston body to constitute the annular cooling tube.

Figure N°19 is a schematic view showing the first step to conform the fin metal sheet ring, according to the method herein for the case wherein the cross section of the fin ring being conformed, is like a “U” with straight branches.

Figure N°20 is a vertical section scheme representing a step to conform the fin ring, subsequent to the one represented in the previous figure.

Figure N°21 is a vertical section scheme representing another step of conforming the fin ring, subsequent to the one represented in the previous figure.

Figure N°22 is a vertical section scheme representing another step of conforming the fin ring, subsequent to the one represented in the previous figure.

Figure N°23 is a schematic view showing the first step to conform the fin metal sheet ring, according to the method herein, for the case wherein the cross section of the fin ring being conformed, is like a “U” of curved branches.

Figure N°24 is a vertical section scheme representing a step to conform the fin ring, subsequent to the one represented in the previous figure.

Figure N°25is a vertical section scheme representing a step to conform the fin metal sheet ring, subsequent to the one represented in the previous figure.

Figure N°26 is a vertical section scheme representing a step to conform the fin ring, subsequent to the one represented in the previous figure.

Figure N°27 is a vertical section scheme representing a step to conform the fin ring, subsequent to the one represented in the previous figure.

Figure N'28 is also a vertical section scheme that, in this case, represents the adjustment or calibrating step of the diameters of the fins of the “U” channel of the fin ring being conformed according to the method herein, in case it is required.

Figure N°29 is a vertical section scheme that, in this case, shows that with this inventive method, it is possible to conform a fin ring capable of coupling to a support hoop such as the one represented in figures 31 and 32.

Figure N°30 is a vertical section scheme representing a step to conform the fin ring, subsequent to the one showed in the previous figure.

Figure N°31 is a vertical section scheme showing the fin ring conformed according to figures 14 and 15, when it is presented in the carrier hoop for its mounting.

Figure N°32 is also a vertical section scheme showing the final mounting of the fin metal sheet ring in a preferred carrier hoop, according to the inventive method.

It should be noted that, in each figure, same referential numbers and letters correspond to the same or equivalent constitutive parts or elements, according to the example selected for the present explanation of the inventive manufacturing method.

DETAILED DESCRIPTION OF A SELECTED EXAMPLE

As it can be contemplated in Figure N°1, the mounting referred to in the present invention, is intended to be applied to the pistons —1- being used by the internal combustion engines.

As it is well known the piston, together with the hoops (not illustrated), should effectively seal the combustion chamber avoiding the entrance of hot gas and lubricant oil at any work condition. On the other side, it is already known that portion —2- usually called piston head is the one more exposed to the thermal and mechanical requirements.

Therefore, there currently exist various pistons that include cooling galleries —3- arranged in the body of each head —2-.

The purpose of these cooling galleries —3- is to counteract the heating in said zone when the temperature is excessive. Thus, a cooling liquid, such as the engine oil, circulates through said internal tube -3-, that by passing through tubes —4- keeps communication with the inside of the piston. That is to say, a certain amount of the lubricant oil itself stirring with the piston movement, also enters into the internal cooling tube —3- absorbing the heat of the inside of the head body —2-.

Normally, the piston body is of an aluminum constitution and is molding manufactured, while the mentioned cooling tubes —3- are formed with a metal sheet ring — 5- welded to a carrier hoop —6- that is usually cast iron with nickel and copper, said cooling tubes are placed into the constitution die , previous to the tapping, such that they are kept into the inside of the piston body. Under these circumstances, the piston integrity and its structure are kept.

As it is contemplated in said Figure N°1, the cooling tube —3- is an annular tube which walls are constituted with the referred metal sheet ring and the internal radial surface —7- of the carrier hoop —6-.

What the present invention specifically intends to cover is the mounting that has been created such that the constitution of the cooling tube —3- by the welding union of the metal sheet ring 5- with its carrier hoop —6- may be effective, of low cost and above all, make sure the non-entrance of aluminum during all process of the piston tapping.

Preferably, the set of pieces constituting the mounting of this invention, has the same expansion coefficient as the aluminum.

Indeed, as it is shown in figures 2 through 6, the mounting achieved is prominent as the carrier hoop —6- presents two annular seats —8- and —9- matching its inside face. These annular seats are similar, opposite and symmetric to each other and keep separated to each other by a body path of the same carrier defining the inside radial surface —7- of the annular cooling tube -3- being constituted.

The presence of these seats —8- and —9- results interesting as in each of them a double support is established for the free ends of the fins —10- and —11- of the folded metal sheet ring —5-. One of the supports is the annular surface in a diametrical direction and the other one is the annular surface in axial direction that conforms the annular seats -8- and —

In this way, what is achieved is that the welding, establishing the union of both pieces —5- and —6-, provides an hermetic closure that avoids the entrance of aluminum to ] the annular cooling tube —3- or the exit of hot gas from the inside of said tube —3- towards the liquid aluminum recently poured into the mold, as these effects generate the rejection of the piston that is being constituted.

As it is shown in said figures 2 through 6, the mentioned double support for each annular seat —8- and -9- is prominent due to the fact that said annular seats make sure the welding will be supported on body of the carrier hoop, which is highly advantageous for the ability to resist any type of mechanical solicitudes as well as the stress that generate whenever temperature changes occur. That is to say; the welding bead —12- always acts as a sealing mean and the body of the carrier hoop provides the mechanical resistance.

What is established in the previous paragraph is highly noted due to the fact that there exist many cases wherein the free ends of the fins of the ring —5- rest upon axial surfaces of the carrier hoop —6-, constituting lineal supports, such that the welding bead is also the closure backing, and therefore the seal being constituted should be well achieved, as otherwise any relative movement produced by the behavior of the materials due to high temperatures may generate cracks.

In these six figures (2/6) different design options are shown that respond to the constructive principle indicated in the two previous paragraphs and, in turn, each of them adapts to different constitution criteria for the cooling tubes —3- that are required by the suppliers. These figures show that the inventive mounting allows different designs of cooling tube —3-. Accordingly, it is applicable to the different market requirements.

The case represented by figure N°2, shows that the metal sheet ring —-5- is of “U” section of straight fins perpendicular to the carrier hoop body —6-, so that the free ends of fins ~10- and ~11- rest and stop at the mentioned seats —8- and —9- provided by the carrier hoop —6-.

Figure N°3 shows that the metal sheet ring —Sa-, in this case, has fins —10- and ~11-

in convergent direction towards the carrier hoop body, so that the cooling tube —3- being constituted is of a trapezoidal cross section.

Figure N*°4 shows that the metal sheet ring —5b-, in this case, rests on a carrier hoop —6- of truncated cone cross section; accordingly, the annular seats —8- and —9- thereof are oriented in diverging direction, such that the cooling tube —3- being constituted, is also of a trapezoidal cross section and of a major height than that of the mentioned carrier hoop —6-.

Figure N°5 shows another variant of the design of the internal cooling tube —3- whish is possible to be achieved with the inventive mounting. In this case, the fin —11- of the ring —5c¢- is straight and is oriented perpendicular to the seat —9- of the carrier hoop —6-, while the fin —10- starts at a curved path and finishes perpendicular to the diametrical surface of both surfaces constituting the seat —8-. In this case, a cooling tube -3- is also constituted which having a greater height than that of the carrier hoop —6-.

Figure N°6 shows another variant of the design of the internal cooling tube —3- whish is possible to be achieved with the inventive mounting. In this case, the mentioned fins —10- and —11- of the ring —5d-, extending along the respective curves that finish in convergent lines oriented perpendicular to the diametrical surface of both surfaces constituting the mentioned supports —8- and —9- of the carrier hoop —6-.

Now turning to figures 7 through 11, it is possible to understand the constructive solution reached to create the inventive mounting in a simple, quick, of low operative cost and secure way.

Now turning to the section shown in figure N°7, it is possible to understand that the diameter that determines the free end of the fin —10- is shorter than the diameter determining the free end of fin —11- and that the curvature angle with respect to the main web where from the fin —-10- is projecting, is larger than the curvature angle where from the fin —11- is projecting.

It is then a preformed metal sheet ring —5- wherein the length of the projection of fin —10- is shorter than the length of the projection of fin -11-, being this constructive ’ condition highly useful to produce the coupling of the support hoop —6- to this metal sheet ring —5-.

Indeed, now turning also to Figures Nos. 7/11, it will also be understood that the dimensional relation explained in the two previous paragraphs allows ring —5- to enter to face the inside annular face of the carrier hoop —6-. This is due to the fact that the diameter of the free end of fin —10- is always slightly less than the diameter of the path of the radial surface —7- that, pertaining to the support hoop —6-, extends between seats —8- and —9-.

This simple constructive solution resolves, in a highly effective way, the coupling of pieces —5- and —6-.

Figure N°12 shows that, once coupled both the ring —5- and the carrier hoop —6-, only the final stamping on fin —10- will be required to be carried out. Fin —11- keeps positioned having its free end resting on seat —9-, while tool —12- makes pressure on fin — 10- causing its free end to be properly positioned on the annular seat —8-.

Said Figure N°12 shows that the metal sheet ring —5- keeps very well positioned and stable on the carrier hoop —6- bringing a final constitution to the annular cooling tube — 3-, being fins —10- and —11- without stress.

The enlarged detail represented by figure N°13 is, precisely, to show the way the welding process —13- to establish the final union between both pieces —5- and —6- is carried : out.

Indeed, as it is shown in the enlarged details of figures 14 and 15, what makes this mounting different from the other ones currently known, is that the body of the carrier hoop is used as a support to the welding bead —14-, such condition making sure the mounting to be highly stable and secure.

In this preferred example, a welding bead —14- (Figure 15) is shown, said bead is made by a gas embedded voltaic arc. Thus, a bead ~14- is generated, constituted by the free end of fin —10- and a portion of the carrier hoop —6- that comprises the annular seat —

> 24 8- (Figure 14). It is an annular seal constituted by the materials provided by said coupled paths and also a third material may be included in case of being required.

Obviously, this type of coupling also allows the use of other types of welding, such as the electronic beam, high frequency, microplasma, etc. in each case with or without material supply.

The manufacturing method referred to herein has been created to constitute the fin ring —A- that is represented in figure N°16. It is a metal sheet ring such as the ones previously explained to describe the invented mounting.

Now, in order to explain in detail the invented method for the manufacturing of said ring, it is described as a ring that comprises a web —15- where from fins —16- and —17- are projecting to conform an annular channel which dimension and format define the basic structure that the annular cooling tube being constituted there from, should have.

Figure N°17 shows the scheme of a piston —P- for an internal combustion engine.

They are generally made of aluminum and molding manufactured, and include an annular cooling tube ~18- extending matching the top part —19- of the piston.

As it was previously indicated, the purpose of these annular cooling tubes is to counteract the heating of said top zone when the temperature is excessive. Thus, a cooling liquid circulates through said tube, such as the lubricant oil stirring with the piston movement.

The section represented in figure N°18 shows the way these annular cooling tubes — 18- are constituted according to prior disclosures and also according to embodiments currently existing in the market. A fin metal sheet ring —A- attached to a support hoop -20- may be appreciated.

Said figure N°18 clearly shows the annular cooling tube being defined, it comprises the inside surface —21- of the carrier hoop, the fins ~16- and —17- and the web —15- of the metal sheet ring —A-.

It is the main object of this invention a novel method for the construction of the referred fin metal sheet ring —~A- to be then attached, by welding, to the carrier hoop —20- : constituting an annular cooling tube capable of being effective in the inside of the piston body.

In this preferred example it is shown the case wherein the fin ring —A- responds to a pattern which cross section is a “U” of straight and parallel branches. However, it is noted that the inventive manufacturing method is created to conform other fin rings of variable formats and designs. As it appears from the functional explanation below described, it will only be required to change the stamping dies.

Figures 19 through 22 represent the steps of the process to create the ring —A- with straight and parallel branches to each other.

Figure N°19 shows that the first step consists of stamping in a die a flat metal sheet -22- by means of a cut tool —23-, being obtained a flat disk plate —24- from which the ring —A- will be conformed.

This first constitution step is highly important as for the construction of these metal sheet rings, it starts as from a flat metal disk of easy manufacturing and low cost.

Indeed, in most cases, it starts from a cylindrical ring constituted by a folded metal sheet which ends are attached by welding. Instead, with this inventive method, it was found the way to avoid the ring being constituted by means of a welding union. A sole annular body is obtained, disappearing the welding thereof, which is highly important for the behavior required to these pieces.

Figure N°20 shows that the second constitution step is made by means of a first constitution stamping or a deep stamping. Disk —24- already constituted in the previous step is mounted and through dies —25/26- the first annular fold is produced, wherein die — 25- presents a design that contemplates the creation of fins.

Figure N*21 shows that a third constitution step consists of constituting a metal sheet ring by means of cutting and removing the circular bottom -27- presented in the piece treated in the previous step. Thus a cut-die —28- is used and the corresponding support —29-. At the same time, due to a cooperating action of these dies, the fin —17- of ] the ring being conformed is born.

Figure N°22 shows a further step wherein the ring being conformed in the previous step is reversed and placed in a base support —30- provided from a seat that responds to the final format and dimension of the annular fin —17-, while the fin —16- is conformed by stamping using the tool ~31- that, as it is shown in this figure, includes an active path —18- specially designed to provide a desired constitution of this fin —16-.

At this point, it is possible to contemplate other advantages of the claimed method, such as the fact that by changing the design of the active surface of said cut-die -28- matching the path generating the fold that allows fin —17- to be born, another format, orientation or dimension for each fin may be designed.

The same occurs to the stamping die —31- that is shown in figure N°22, wherein the mentioned active surface —32- will have a design according to the dimension, orientation or transition curvature angle established by the manufacturer with respect to the design of the cooling channel that is going to be produced.

It should be understood, according to what stated in the previous two paragraphs, that it will be enough to have sets of dies according to the different annular cooling tubes being required by clients, to produce all the existing designs in the market; whenever all the steps established in this novel method are followed, starting from a metal sheet flat disk.

Just to illustrate which was said in the previous paragraph, figures Nos. 23/27 are included to show how the inventive method allows the conformation of a metal sheet ring which profile responds to a “C” of curved fins.

Figure N°23 shows that the first constitution step is the same in each case. (See Fig.

N°19).

Once the metal disk -24- is obtained, the second conformation Step starts,

represented in figure N°24, wherein the stamping die —34-, presents an annular path —33- of its active surface that responds to a foreseen pattern to bring a pre-format different to what ] the fin —17°- will be; while base —35- responds to a pattern cooperating with such design, that is appreciated in its annular path —33°-.

The step of removing the bottom —37-, is also similar to the one indicated in figure 21; while in the steps shown in figures 26 and 27, stamping dies —38-, -39-, -40-, and —41- appear, specially created to bring a final form to a cross sectional metal sheet ring according to a “C” of curved fins —16’- and -17-,

Now turning to figure N°28, it is appreciated, in detail, the subsequent calibration step, wherein the metal sheet ring —A- is mounted on a rotating support —42- such that, by means of a cut tool —43- the diameter of the free end of fins —16- and —17- may be precisely determined, as well as eventual rough edges or surface irregularities are removed.

The method herein is specially advantageous to produce metal sheet rings capable to be coupled to an assembly as the one shown in figures Nos. 31 and 32.

It is an assembly wherein the annular support —20- includes a pair of annular coupling steps —44- and —45- created to house the free ends of the fins —16’- and -17’-; said coupling zone is the place where the welding process to constitute the hermetic union seal is carried out.

In order to insert the ring —A- in the support —20-, it is required that each fin ~16’- should have an end diameter less than the diameter of the inside face —46- of said support — 20- (figure N° 31).

Once positioned, the final stamping is carried out by means of tool —47- (figure

N°17).

In this case, it is only required that the stamping tool —44- (figure N°30) makes a pre-form of this fin —16°- limiting its end diameter to the measurement required for the further positioning.

Claims (16)

What is claimed is:

1.- A MOUNTING OF METAL SHEET RING ASSEMBLIED AND WELDED IN A i CARRIER HOOP TO CONFORM THE ANNULAR COOLING TUBE OF A PISTON OF AN INTERNAL COMBUSTION ENGINE, wherein the mounting uses a metal sheet ring, which cross section comprises a web extending between two fins projecting towards the carrier hoop, wherein the free ends of said fins rest on and couple to the annular seats being defined in the internal face of the carrier hoop, matching its curbs of internal edge; where said support and coupling are sealed by respective annular welding beads extending along the mentioned annular seats and rest on the body of the carrier hoop, being conformed an internal annular cooling tube which inside surface is constituted by a metal sheet ring and the internal diametrical surface of the carrier hoop extending between both annular seats.

2.- A MOUNTING OF METAL SHEET RING ASSEMBLIED AND WELDED IN A CARRIER HOOP, according to claim 1, wherein the fins of the metal sheet ring are oriented in convergent direction towards the carrier hoop.

3. A MOUNTING OF METAL SHEET RING ASSEMBLIED AND WELDED IN A CARRIER, according to claim 1, wherein the fins of the metal sheet ring are oriented in perpendicular direction towards the carrier hoop.

4.- A MOUNTING OF METAL SHEET RING ASSEMBLIED AND WELDED IN A CARRIER HOOP, according to claim 1, wherein the body of the carrier hoop is of a truncated cone cross section and the fins of the metal sheet ring are oriented in convergent directions towards the respective annular seats of the carrier hoop.

5. A MOUNTING OF METAL SHEET RING ASSEMBLIED AND WELDED IN A CARRIER HOOP, according to claim 1, wherein one of the fins of the metal sheet is oriented in perpendicular direction to the body of the carrier hoop and the other one follows a curved line and then finishes in a final straight path extending up to the seat, which is in cross direction to the carrier hoop.

6.- A MOUNTING OF METAL SHEET RING ASSEMBLIED AND WELDED IN A CARRIER HOOP, according to claim 1, wherein both fins of metal sheet are curved having the ending paths thereof oriented in cross direction to the carrier hoop.

7.- A MOUNTING OF METAL SHEET RING ASSEMBLIED AND WELDED IN A CARRIER, according to claim 1, characterized in that the height of the metal sheet ring is greater than the height of the carrier hoop.

8.- A MOUNTING OF METAL SHEET RING ASSEMBLIED AND WELDED IN A CARRIER HOOP, according to claim 1, wherein the annular welding beads resting on the carrier hoop are defined on the annular seats of said hoop confined in a double resting support.

9.- A MOUNTING OF METAL SHEET RING ASSEMBLIED AND WELDED INA CARRIER HOOP, according to claim 1, wherein for the coupling of the metal sheet ring at the carrier hoop, said ring previously presents one of its fins tear down with different angles, such that the diameter of the free end of one of them is less than the diameter of the free end of the other one.

10.- A MOUNTING OF METAL SHEET RING ASSEMBLIED AND WELDED INA CARRIER HOOP, according to claim 8, wherein the diameter of the free end of one of the fins is less than the internal diameter of the carrier hoop.

11.- METHOD TO MANUFACTURE A FIN METAL SHEET RING, that consists of taking a flat metal sheet of adequate thickness, cutting the same conforming a circular disk; producing, by stamping over such disk, a circumferential wall having a folded edge of diverging fin; cutting and removing its circular bottom, by stamping over the constituted piece in the previous step; taking the constituted ting in the previous step and conforming a second folded edge of diverging fin by stamping over the circular edge opposite to the one already existing in the first diverging fin;

12. METHOD TO MANUFACTURE A FIN METAL SHEET RING according to claim 11, wherein once obtained both folded edges, the fin ring produced in the previous step 1s placed in a rotating support and submitted to a final calibration by means of cut tools acting on the circumferential edges of both fins.

13.- METHOD TO MANUFACTURE A FIN METAL SHEET RING according to claim 11, wherein stamping dies comprise a support piece and a stamping tool which active surfaces of cooperating action, that lock the metal sheet which they act on, present peripheral paths of such a form responding to the foreseen design for the metal sheet ring being constituted.

14. METHOD TO MANUFACTURE A FIN METAL SHEET RING, according to claim 11, wherein the cutting being produced on the metal sheet in the first step, is carried out by means of a circular cut-die by stamping.

15. A FIN RING OF METAL SHEET, obtained by the method of claim 1 1, wherein it consists of a sole body of metal sheet which cross section is a “C” profile which diverging fins respond to different pre-established designs.

16. A FIN RING OF METAL SHEET, according to claim 15, wherein the different pre-established designs for the diverging fins of the metal sheet ring may have different orientations, curvatures and dimensions thereof.