EP0231311A1

EP0231311A1 - Method for fabricating by casting a metal part which is internally provided with a recessed portion surrounded by a tube

Info

Publication number: EP0231311A1
Application number: EP19860904842
Authority: EP
Inventors: Gaston Marie Jean Henri Sauvage De Saint Marc; Maurice Eugène Jules ROCHE
Original assignee: FONDERIES ET AFFINAGE DE L'ISERE
Current assignee: FONDERIES ET AFFINAGE DE L'ISERE
Priority date: 1985-07-31
Filing date: 1986-07-31
Publication date: 1987-08-12
Also published as: WO1987000779A1; FR2585598A1; FR2585598B1

Abstract

Procédé de fabrication d'une pièce métallique (29), en particulier d'une pièce métallique massive, munie intérieurement d'une partie évidée, en particulier d'une partie évidée de faible section et de profil quelconque, comprenant une coulée de métal (29a) autour d'un tube (20) entourant ladite partie évidée et réalisée dans le même métal que celui que l'on désire couler, ou dans un métal ayant une température de fusion voisine de celle de ce métal, et le passage simultané dans ledit tube (20) d'un fluide de refroidissement diphasique liquide-gaz porteur, dans lequel une suspension turbulente de très fines gouttelettes de liquide atomisées dans le gaz porteur est introduite dans ledit tube par l'une des extrémités, consistant à prévoir dans ledit tube par l'une des extrémités, consistant à prévoir dans ledit tube (20) des moyens (27) permettant d'augmenter et/ou d'entretenir la turbulence de l'écoulement du fluide diphasique de refroidissement dans ledit tube (20).Method for manufacturing a metal part (29), in particular a solid metal part, internally provided with a hollowed out part, in particular a hollowed out part of small cross section and any profile, comprising a metal casting ( 29a) around a tube (20) surrounding said hollowed-out part made of the same metal as that which it is desired to cast, or in a metal having a melting temperature close to that of this metal, and the simultaneous passage through said tube (20) of a two-phase liquid-carrier gas coolant, in which a turbulent suspension of very fine droplets of liquid atomized in the carrier gas is introduced into said tube by one of the ends, consisting of providing in said tube by one of the ends, consisting in providing in said tube (20) means (27) making it possible to increase and / or maintain the turbulence of the flow of the two-phase cooling fluid in said tube (20).

Description

"Method of manufacturing by casting a metal part provided internally with a recessed part surrounded by a tube".

The present invention relates to a method of manufacturing a metal part, in particular a solid metal part, provided internally with a recessed part, in particular with a recessed part of small cross section and any profile, comprising a casting of metal around a tube surrounding said hollowed-out part made of the same metal as that which it is desired to pour, or in a metal having a melting temperature close to that of this metal, and the simultaneous passage through said tube a two-phase liquid-carrier gas coolant, in which a turbulent suspension of very fine droplets of liquid atomized in the carrier gas is introduced into said tube by one of its ends.

Such a manufacturing process is described in the French patent published under No. 2,379,340. This process is particularly suitable for the production of metal parts, in the foundry or steel industry, containing a recess or internal channel for for example a circulation of a fluid intended to cool or heat the mass of the metal part during its use.

According to this known method, the metal part is obtained by forming a metal tube, which may have a thin wall, so as to produce a coil with the desired profile and the casting of the metal around this tube which is thus embedded in the metallic mass.

In order to avoid that, during the pouring of the metallic mass, the wall of the metallic tube does not pierce and that the hollowed parts cannot be obstructed, or else that the metallic tube undergoes by softening of the deformations, this known method to circulate, at relatively high speeds, inside the metal tube, a two-phase liquid-carrier gas mixture with dispersed or atomized liquid phase, appearing, at the inlet of the metal tube, in the form of a suspension turbulent. By the shock effect of fine liquid droplets of the two-phase mixture circulating on the heated internal walls of the metal tube, causing them to evaporate, the heat exchanges between the metal tube and the two-phase cooling fluid are favored.

With this known method, although it offers excellent results, it is feared that the connection between the cast metal and the metal tube, forming the hollowed-out part or internal channel, is not perfect over the entire length of the metal tube and over its whole periphery and that there remain spaces filled with air, even very small. Indeed, during the use of the metal part obtained by this known manufacturing process, such spaces filled with air create a thermal insulation relatively considerably limiting the heat exchanges between the fluid circulating in the internal channel and the metallic mass. .

Such link discontinuities can cause significant and localized heating which is detrimental to the good performance of the metal part. Indeed, the differences in temperature between the overheated zones and the normally cooled zones can generate mechanical stresses and local flow which can increase the volume of the air-filled spaces, cause others, cause cracks which, developing , are likely to ultimately lead to the destruction of the metal part.

The present invention aims in particular to remedy the above drawbacks and proposes a method of manufacturing a metal part by casting in which is inserted a metal tube delimiting a hollowed out part or an internal channel in this metal part which can advantageously constitute an improvement of the manufacturing process known above.

The manufacturing method according to the present invention is such that it consists in providing in said metal tube means making it possible to increase and / or maintain the turbulence of the flow of the two-phase cooling fluid in said tube over its entire length. .

Thanks to the process of the present invention, it is advantageously possible to prevent the very fine droplets of liquid atomized in the carrier gas from agglomerating in order to maintain over the entire length of the tube an efficient and homogeneous dispersion of the liquid in the carrier gas and to conserve , and even increase, the efficiency of the heat exchanges between the metal tube and the two-phase cooling fluid, the cooling being all the better as the liquid droplets atomized in the carrier gas remain very fine and the flow in the metal tube remains turbulent.

The manufacturing process of the present invention can also make it possible to reduce the quantity of atomized liquid of the two-phase cooling fluid and to avoid very high flow rates in the metal tube as well as the dangers which are likely to result therefrom. .

The advantages of the manufacturing method according to the present invention, combined with the advantages of the manufacturing method of French Patent No. 2,379,340 can advantageously contribute to the production of metal parts containing an internal channel or a hollowed-out quality part.

The manufacturing process according to the present invention can be carried out in different ways. In a variant, it may consist in having inside said metal tube means making it possible to modify the direction of flow of the two-phase cooling fluid in this metal tube.

It may consist in having, in particular inside the end part of said metal tube, on the inlet side of the two-phase cooling fluid, a profile of substantially helical shape.

It may consist, in another variant, of having, inside said metal tube, an axial cable extending over at least part of the length of the metal tube and carrying a multiplicity of substantially radial fins spaced in the direction longitudinal of the cable.

The method according to the present invention may consist, in another variant, of providing a metal tube having one or more longitudinal parts of modified section. One can in fact provide, in accordance with the present invention, a tube having one or more ovalized longitudinal parts or one or more longitudinal parts of narrowed section. In this case, it is desirable that the longitudinal part (s) of modified section have internal surfaces without discontinuity with respect to the internal surface of the metal tube in order to avoid any zones in which both the two-phase cooling fluid during manufacture of the metal part that the fluid circulating in the internal channel of the metal part manufactured would be likely to stagnate or to circulate at reduced speed. The present invention will be better understood from the study of modes of implementation described by way of nonlimiting examples and illustrated by the drawing in which:

FIG. 1 shows an external view of a first embodiment, the metal tube in the form of a serpentine being embedded in a metallic mass represented in section,

- Figure 2 shows an axial section along II-II of Figure 1 of an end portion of the metal tube;

- Figure 3 shows a radial section on III-III of Figure 2;

- Figure 4 shows a radial section on IV-IV of Figure 1 of the bent portion of the coil;

- Figure 5 shows a narrowed area of a straight part of the coil of Figure 1; - Figure 6 shows, in section through a median plane another embodiment in which a cable provided with blades is disposed inside the metal tube in the form of a serpentine;

- Figure 7 shows an enlarged exterior view of the cable provided with tabs, with its attachment device; - Figure 8 shows an end view of this attachment device.

In the first embodiment shown in FIGS. 1 to 4, it can be seen in FIG. 1 that the metal tube generally identified by the reference 1, of generally circular section and with a thin wall, has two parallel branches 2 and 3 which are connected by an elbow 4. Of course, the coil 1 could have other shapes possibly developing in three dimensions. The end 2a of the branch 2 of the metal tube I carries a device 5 for atomizing a liquid such as water in a carrier gas such as nitrogen.

Referring to Figures 2 and 3, we see that this atomization device 5 has an atomization chamber 6 which extends in the extension of the internal channel of the end 2a of the metal tube 1 and which is surrounded by a outer wall 7, one of the ends 7a. is screwed onto the end 2a of the metal tube 1 and the other end of which 7b has an axial channel 8 for the arrival of a carrier gas such as nitrogen. In a direction tangent to a cross section of the chamber 6 opens a pipe 9 forming a nozzle which passes through the wall 7 and which is connected to a pipe 10 for supplying a liquid such as water. Between the threaded end 7 a of the external wall 7 and the inlet of the tangential channel 9, are arranged, in the chamber 6, two diaphragms 11 and 12, spaced apart, which have axial passages and which are separated by a spacer 11a . During the injection of the carrier gas into the atomization chamber 6 through the channel 8 and the introduction of liquid through the tangential channel 9, a mixture of two-phase fluid occurs and is introduced into the metal tube 1 through its end 2a by passing successively through the diaphragms 11 and 12, this two-phase fluid introduced having a turbulent suspension of very fine droplets of liquid atomized in the carrier gas.

Referring to Figures 2 and 3, it is further seen that, in the end portion 2a of the metal tube 1 is disposed an element generally identified by the reference 13, of relatively great length compared to the section of the metal tube 1, which has an axial rod 14 whose inner end 14a is free and whose outer end 14b is carried by a radial plate 15 which is provided with three large longitudinal passages 16a, 16b and 16c and whose periphery is inserted between the end of the branch 2 of the metal tube l and a spacer 12a which is at its other end bearing on the diaphragm 12.

The rod 14 carries at its periphery a profile 17 of helical shape with a large pitch which extends from one of the radial branches of the plate 15 to the end 14a of this rod 14 and which is thin . The envelope of the helical profile 17 is slightly conical in the direction of the end 14a of the rod 14, its largest diameter being equal to or slightly less than the inside diameter of the metal tube I, so as to leave a flow space between its outer edge and the inner wall of the tube 1.

Referring to Figure 4, we see that the bent part 4 of the metal tube 2 is continuously ovalized from the inner wall of the tube 1 and, referring to Figure 5, we see that the branch 3 of the metal tube 1 has, substantially at mid-length, a narrowed portion 18, without discontinuity of the internal wall of the metal tube 1.

When casting the metallic mass 19a around the serpentine-shaped metal tube I, in order to manufacture the part 19 of FIG. 1 provided with an internal channel, the two-phase cooling fluid generated by the atomization device 5 is introduced into the metal tube 1 by its end 2a.

Thanks to the profile 7 of the element 13 disposed in the end portion 2a of the metal tube 1, the two-phase fluid flowing is strongly deflected and its turbulence is consequently considerably increased.

Similarly, when the two-phase cooling fluid flows through the bent oval part 4, its flow undergoes a deformation which, at the exit of this oval part, generates an increase in turbulence. An equivalent result is obtained when the two-phase cooling fluid crosses the narrowed part 18 of the branch 3 of the metal tube 1.

It should therefore be observed that, when the two-phase cooling fluid flows through the metal tube 1, its turbulence is maintained or increased, so that the two-phase cooling fluid retains or increases its exchange capacities thermal with the metal tube 1, capacities due to the significant degree of atomization of the liquid in the carrier gas and to its maintenance.

Referring to Figures 6 to 8, we will now describe another alternative embodiment.

It can be seen in FIG. 6 that, in this variant, the metal tube 20 produced in the form of a serpentine has four branches 21 to 24 which are substantially parallel and which are successively connected by three elbows.

The end 21a of the first branch 21 of the coil 20 carries an atomization device 25 equivalent to the atomization device 5 visible in FIG. 2 of the previous example. Inside the metallic tube 20, and over its entire length, is disposed a cable 26, preferably metallic, which carries, spaced apart in the direction of its length, a multiplicity of radial elements 27 and which is of very smaller diameter to that of the tube 20. Referring to FIGS. 7 and 8, it can be seen that the end 26a of the cable 26, situated on the side of the atomizing device 24, is hooked to a plate 28 similar to the plate 15 of the device d atomization 5 of the previous example visible in Figure 2, plate 28 which has three longitudinal passages 28a to 28c and which is inserted between the end of the branch 21 of the metal tube 20 and the atomization device 24 in the same manner as above.

In these Figures 7 and 8, we see that the elements 27 have two opposite radial fins 27a and 27b which extend from a sleeve 27c crimped on the cable 25. The tabs 27a and 27b of the elements 27 are such that their wingspan is less than the diameter of the metal tube 20. In the example, the tabs 27a and 27b extend in a radial plane and substantially form a rectangle whose width is much less than the diameter of the metal tube 20.

When casting the metal mass 29a around the metal tube 20 in the form of a serpentine, in order to produce the metal part 29 provided with an internal channel visible in FIG. 6. one injects into the metal tube 20, by its end 21a, a two-phase cooling fluid with turbulent suspension produced in the atomization device 25. During its flow through the metal tube 20, this two-phase cooling fluid collides with the various elements 27 carried by the cable 26 and consequently its turbulence is maintained or increased with the passage of each element 27. It follows that the heat exchanges between the two-phase cooling fluid and the metal tube 20, which cause the vaporization of the fine droplets of liquid kept in suspension, are excellent over the entire length of the metal tube 20. The present invention is not limited to the examples described above. In particular, any combination of the above embodiments can be produced. Many other alternative embodiments are possible without departing from the scope defined by the appended claims.

Claims

1. Method for manufacturing a metal part (19; 29), in particular a solid metal part, provided internally with a hollowed-out part, in particular a hollowed-out part of small cross section and of any profile, comprising a casting of metal (19a; 29a) around a tube (1; 20) surrounding said hollowed-out part made of the same metal as that which is to be cast, or in a metal having a melting temperature close to that of this metal, and the simultaneous passage through said tube of a two-phase liquid-carrier gas coolant, in which a turbulent suspension of very fine droplets of liquid atomized in the carrier gas is introduced into said tube by one of its ends , characterized in that it consists in providing in said tube (1; 20) means (13, 4, 18, 27) making it possible to increase and / or maintain the turbulence of the flow of the two-phase fluid of cooling in said tub e over its entire length.

2. Method according to claim 1, characterized in that it consists in placing inside said metal tube means making it possible to modify the direction of flow of the two-phase cooling fluid in this metal tube.

3. Method according to one of claims 1 and 2, characterized in that it consists in placing inside the end part of said metal tube (1), on the inlet side of the two-phase cooling fluid, a profile ( 17) of substantially helical shape.

4. Method according to any one of the preceding claims, characterized in that it consists in placing inside said metal tube (20) an axial cable (26) extending over at least part of the length of the latter and carrying a multiplicity of substantially radial tabs (27) spaced apart in the longitudinal direction of the cable.

5. Method according to any one of the preceding claims, characterized in that it consists in providing a metal tube (1) having one or more longitudinal parts of modified section (4, 18).

6. Method according to claim 5, characterized in that it consists in providing a tube having one or several longitudinal parts of oval cross section (4).

7. Method according to claim 5, characterized in that it consists in providing a tube (1) having one or more narrowed longitudinal parts (18).

8. Method according to any one of claims 5 to 7, characterized in that the longitudinal part or parts of modified section have interior surfaces without discontinuity with respect to the internal surface of said metal tube.