WO2019137840A1

WO2019137840A1 - Cold crucible and associated cooling manifold for an induction heating device

Info

Publication number: WO2019137840A1
Application number: PCT/EP2019/050046
Authority: WO
Inventors: Richard HAETTEL
Original assignee: Centre National De La Recherche Scientifique
Priority date: 2018-01-09
Filing date: 2019-01-02
Publication date: 2019-07-18
Also published as: FR3076602B1; EP3737901A1; EP3737901B1; FR3076602A1

Abstract

The present invention relates to a cold crucible for an induction heating device for heating and melting materials such as metals. The crucible comprises a crucible body that is in the general shape of a tube or of a test piece, the peripheral partition of which comprises a plurality of sections in the shape of arcs of a circle separated from each other by an air space. Each section contains a cooling pipe circulating a coolant in order to cool the crucible during operation. The present invention also relates to a cooling manifold, which, during operation, is connected to the crucible body and which allows the coolant to be distributed through the various pipes. The invention also relates to a method for manufacturing the crucible. The field of the invention is particularly that of metallurgy and foundries.

Description

"Cold crucible and associated cooling collector for induction heating device"

The present invention relates to a cold crucible for induction heating apparatus for heating and melting materials such as metals. The crucible comprises a crucible body which has the general shape of a tube or test-tube, the peripheral wall of which comprises a plurality of arcs-shaped sections separated from one another by an air gap . Each section contains a cooling pipe circulating a cooling liquid to cool the crucible in operation. The present invention also relates to a cooling manifold which, in operation, is connected to the crucible body and which allows to distribute the cooling liquid in the various pipes. The invention also relates to a method of manufacturing the crucible. The field of the invention is in particular that of metallurgy and foundry.

State of the art

In the field of materials, it is very often necessary to melt materials, for example to make alloys containing several metals or other materials. A known method is to use an induction heating device, formed of electrical conductors surrounding a so-called "cold" crucible, in which one or more materials to be heated, called "the load". The device includes an inductor winding, surrounding the crucible, to generate a magnetic field inside the crucible and thereby heat the charge by induction. The crucible is cooled to remove heat from the charge and the joule effect of the induced current therein. The crucible has a general shape of tube so that it comprises a peripheral wall forming envelope. This partition is cut longitudinally so that the crucible is formed of several sections in the form of sectors, along the majority of the length of the crucible; the partition being arranged in continuity of material at one end of the crucible. This sectorisation of the crucible is necessary in order to electrically isolate the sections between them, to induce eddy currents in the load and to prevent the field Magnetic provided by the inductor is screened by the crucible. The device also comprises a cooling collector, or water box, distributing cooling water to pipes arranged in the peripheral wall of the crucible. Pipes are also connected by soldering to the crucible and the cooling collector.

However, these solders tend to deteriorate over time, which results in a potential source of contamination for the charge contained in the crucible, significant leakage and therefore a limited life.

EP0398821 proposes brazing cooling tubes on a perforated ring, said ring comprising openings distributed over its circumference for the flow of water between a water collector and the crucible. These openings are distributed over two different circles: a circle formed by the inlet openings, and another circle formed by the outlet openings. A cooling passage is arranged in each sector of the crucible to respectively receive a tube, which separates the input circuit from the output circuit. This embodiment therefore reduces the number of solders but does not respond to the problem of leaks. In addition, it is difficult to achieve solder without altering the brazing of adjacent pipes or pipes, especially during the maintenance of the crucible.

In addition, it is necessary to decontaminate the crucible after each use, or at least between charges of different natures, which is a complex operation and further reduces its life. The contamination occurs because residues and impurities are deposited on the walls of the crucible. In the event of a water leak, a violent reaction of the water with the material to be heated can occur even to the point of explosion.

An object of the invention is to overcome all or part of the disadvantages of the state of the art. Another object of the invention is to provide a cold crucible heating device limiting life problems, sealing defects. It is also intended to provide a device facilitating maintenance compared to known devices. It is also intended to propose operational conditions of manufacture allowing to realize materials of high purity. Finally, it aims to facilitate the use of a heating device in a cold crucible.

Presentation of the invention

According to a first aspect of the invention, at least one of the aforementioned objects is achieved with a cold crucible for an induction heating device comprising a crucible body comprising:

a connecting ring comprising an annular distribution region,

a tubular casing extending from the connection ring to define a heating volume, the casing being cut longitudinally so as to produce several separate sectors in order to induce eddy currents in the charge placed in the heating volume and to prevent the magnetic field supplied by an inductor from being screened by the crucible,

- Channels of coolant disposed longitudinally in the thickness of the crucible body so that each sector comprises at least one coolant channel.

Each sector comprises at least two coolant paths: a so-called "go" path and a "return" path of the coolant. The coolant paths of each sector are formed by the at least one coolant channel. Said paths open into the annular distribution region so that said region has, for each sector, an "inlet" orifice and an "outlet" orifice, the orifices being spaced apart from one another along a radial direction of the crucible.

The assembly thus forms along the periphery of the annular distribution region two distinct concentric regions around the longitudinal axis of the crucible, one of which communicates only with the forward path of the channels and the other communicates only with the return path of the canals.

The crucible body is intended to be removably assembled with a cooling manifold via the connecting ring, the manifold comprising coolant distribution elements connecting to the coolant channels, the made of this assembly, to circulate said liquid between the collector and the channels.

The crucible body has a one-piece structure composed of a single material having a continuity of material on at least two sectors.

The cold crucible according to the invention allows easier use, compared to the crucible of the prior art, limiting or even eliminating, solder operations performed on the crucible and allowing a connection with a collector without angular indexing at the same time. coupling or foolproof system. Therefore the crucible according to the invention limits or even eliminates the sealing defects and provides an increased life. Maintenance is also facilitated over known devices.

For what follows and for the foregoing, the term "longitudinal" means a direction substantially parallel to the axis of the crucible body, plus or minus 15 angular degrees. This axis is generally vertical when the crucible is in the position of use and intended for introduction or vertical extraction. It typically corresponds to the center of the tubular casing, and / or the induction coil that surrounds the crucible.

Preferably, each channel comprises a reported channel partition inserted longitudinally into said channel. The partition forms a tight or substantially watertight longitudinal contact with at least two distinct regions of the peripheral wall of said channel, so as to define the forward path and the return path on either side of said partition and extending longitudinally to the inside the same channel. The added partition allows to form simply and in a small space two paths of coolant. The partition is for example epoxy glass fabric or fiberglass composite.

According to one embodiment, each channel partition has a planar shape. Its cross section is substantially linear and rectilinear in one direction. According to another embodiment, each channel partition has a two-dimensional shape. Two-dimensional means a shape whose cross section is non-rectilinear, for example curved, or comprising at least one element of non-zero thickness on one side of the partition.

Each channel partition is disposed in its channel so that an imaginary geometric plane included in the thickness of the partition is substantially tangential to a cylinder of imaginary revolution concentric to the crucible. This characteristic makes it possible to form in the connection zone of the connecting ring two distinct concentric regions around the longitudinal axis of the crucible, one of which communicates only with the forward path of the channels and the other only communicates with the return path. channels. The connection between the collector and the crucible can be achieved without indexing.

According to one embodiment, each channel wall has a length substantially equal to or less than the length of the channels, and is intended to be inserted into a channel leaving a non-zero gap between the bottom of the channel and the longitudinal end of the channel. passage of the canal partition. In this way the coolant can pass from the outbound to the return journey. For example, each channel wall has a length of at least 75% of the length of a channel.

Preferably, each channel comprises in its wall two distinct grooves arranged and configured to receive and position each partition in said channel. This feature allows a reliable maintenance of the channel walls in position, and can guide them in said channel, improving the reliability of the crucible cooling.

According to a second aspect of the invention, at least one of the abovementioned purposes is achieved with a cold crucible for an induction heating device, characterized in that it comprises a crucible body comprising:

a connecting ring comprising an annular distribution region,

a tubular envelope extending from the connecting ring to define a heating volume, the envelope being cut longitudinally so as to produce several separate sectors,

- Channels of coolant disposed longitudinally in the thickness of the crucible body so that each sector comprises at least one coolant channel. The crucible body is adapted to be removably assembled with a coolant manifold via the connecting ring, the manifold including coolant delivery members connectable to the coolant channels for circulating said liquid.

According to the second aspect of the invention, said crucible body has a one-piece structure composed of a single material having a continuity of material on at least two sectors.

The cold crucible, according to the second aspect of the invention, allows easier use, compared to the crucible of the prior art, limiting or even eliminating the solder operations performed on the crucible. Therefore the crucible according to the invention limits or even eliminates the sealing defects and provides an increased life. Maintenance is also facilitated over known devices.

According to a variant of the first or second aspect of the invention, the crucible body consists essentially of:

a connecting ring comprising an annular distribution region,

a tubular envelope extending from the connection ring to define a heating volume, the envelope being cut longitudinally so as to make several separate sectors, and

According to another variant, the crucible is formed by a plurality of monoblock elements, each comprising several sectors formed in the same room. These multi-sector monoblock elements each form an angular portion of the crucible and are assembled together by removable mechanical means, for example individual screws or a common flange all maintaining them against the cooling collector. Even in this variant, it greatly limits the number of mechanical fasteners, and retains good reliability and non-contamination qualities. Preferably, according to any aspect or variant, the crucible body has a one-piece structure composed of a single material having a continuity of material between the connecting ring, the sectors of the envelope and the channels. This feature has the advantage of further improving the mechanical strength of the crucible and maintain the geometry of the crucible body during use. This parameter makes it possible to have a more homogeneous electromagnetic field and thus a more homogeneous heating of the load. When it comes to melting a material, a better stability of the molten metal bath is obtained. This stability is particularly important when it comes to making an alloy and let dissolve, by diffusion in the liquid, each of the constituent elements of the alloy. If the instability of the bath of molten metal becomes too great, the liquid metal is thrown against the walls of the crucible and solidifies immediately which prevents its homogenization.

According to the first or second aspect of the invention, the body of the crucible is made of an electrically conductive material and thermal conductor.

According to a preferred embodiment, the body of the crucible is made of copper produced by hardening. In the prior art, the soldering operation on the crucible generates the annealing of the copper, which makes the crucible malleable. Without soldering carried out on the copper crucible body according to the invention, the latter does not undergo annealing and thus remains rigid (without deformation). In addition, the copper has a very good thermal conductivity which allows cooling by conduction from the cooling channels to the ends of the sectors. Alternatively, the body of the crucible could be stainless steel.

According to an embodiment compatible with the first aspect as the second aspect, the connecting ring comprises on its periphery a crucible thread arranged to allow a screw connection so that a cooling collector, provided with a thread of collector which is complementary to it, can be screwed on the crucible or vice versa. This characteristic makes it possible to mount and dismount the collector of crucible cooling easily and quickly to improve the decontamination of the crucible after each use.

Thus, the crucible body comprises a monobloc element, forming several sectors which are all separated from each other by longitudinal cuts to their distal end and over their entire length except in the region of the connecting ring, said proximal region. Typically, each sector thus delimited comprises only one cooling channel. This cooling channel forms a blind hole, that is to say with only one end opening longitudinally, which blind hole is separated into two longitudinal paths by an attached partition which is inserted by this emerging end. Preferably, a single monobloc element forms all the sectors, and thus constitutes the entire envelope of the crucible body.

For the continuation and for the above, by distal end is meant an end located near the bottom of the crucible body, and by proximal end is meant an end located near the connection ring of the crucible.

According to a third aspect of the invention, which may be wholly or partially in accordance with the first aspect or all or part of the second aspect of the invention, at least one of the aforementioned objects is achieved with a cooling collector intended to cooperate with a cold crucible for an induction heating device, the crucible comprising:

a connecting ring comprising an annular distribution region,

- Channels of coolant disposed longitudinally in the thickness of the crucible so that each sector comprises at least one coolant channel comprising a channel wall, forming in each channel at least two paths opening respectively by two spaced openings l of each other along a radial direction of the crucible on the annular region of the connecting ring. The collector is characterized in that it has two collector cavities which are substantially circular and are arranged on the same face coming opposite the connecting ring, the collector cavities being offset in a radial direction by relative to the collector axis so that each collector cavity is located above a single orifice of each channel once the collector and the crucible are assembled.

The cooling collector according to the invention allows easier use, compared to the collector of the prior art, allowing a connection with a collector without indexing. Therefore the collector according to the invention limits or even eliminates the sealing defects and provides an increased life. Maintenance is also facilitated over known devices.

The two cavities are arranged to provide an inlet chamber and an outlet chamber connectable to a coolant circulation circuit.

Preferably, the collector comprises a circular collector partition separating said two collector cavities. Advantageously, a single collector partition separates said two collector cavities, which makes it possible to limit the size and ease of mounting relative to the crucible body. For example, said collector partition bears against so-called sealing ends of the channel partitions. According to one embodiment, the collector partition has a cone shape.

According to one embodiment, the collector comprises, around the collector cavities, a collector thread arranged to allow a screw connection so that a crucible body also comprising a complementary crucible thread can be screwed onto the collector or vice versa . This feature makes it easy to connect the cooling manifold to a crucible body.

Preferably, the cooling collector is made of stainless steel.

According to a fourth aspect of the invention, one of the abovementioned goals is achieved by an induction heating device comprising a cold crucible body according to all or part of the first aspect or all or part of the second aspect and a cooling collector according to all or part of third aspect of the invention. According to this fourth aspect, they are arranged so that, when assembled together, the coolant distribution elements of the collector are connected to the coolant channels of the crucible body

According to a fifth aspect of the invention there is provided a method of manufacturing a cold crucible for induction heating device, the crucible comprising a crucible body communicating with a cooling collector, the crucible body comprising a tubular envelope s extending from the cooling collector and surrounding a heating chamber included in a heating volume, the casing being cut longitudinally so as to make several separate sectors, cooling liquid channels arranged longitudinally in the thickness of the crucible so as to each sector comprises at least one coolant channel, the method comprising the following steps:

- providing one or more one-piece starting parts or blanks, a thermal and electrical conductor material, preferably copper, for example a round or a tube,

for each starting piece, machining the part with the desired external and internal dimensions, according to the desired crucible size, to produce a crucible body forming a connecting ring from which the tubular envelope extends.

The manufacturing method comprises, in this order or in another, the following steps:

- Make a crucible thread on the periphery of the connecting ring,

- Make bores corresponding to the coolant channels and opening into the surface of the connecting ring,

- Make two grooves, diametrically opposed, in the wall of each channel.

- Make longitudinal cuts on the envelope through the entire thickness of the envelope, the cuts extending between the ring of connection and up to the end of the crucible body opposite the ring.

The manufacturing method according to the invention makes it possible to produce a crucible body proposing operating conditions of manufacture making it possible to produce materials of high purity.

Preferably, a round of high purity copper is chosen. The preferred copper grades are between the Cu-Al and Cu- C2 ranges according to the AFNOR standard, that is to say:

- Cu-Al: used for the manufacture of wires, bars and tubes for electrical use, high electrical conductivity, good resistance to chemical agents,

- Cu-C2: very high purity copper, electrical and electronic use, good welding ability, refined oxygen-free copper; the category CU-C2, with its purity and especially its oxygen limited to 5ppm is better suited to applications requiring a high vacuum.

The Cu-C2 grade is the preferred grade because the purest and the one that degasses the least, and is particularly suitable for use under ultra-high vacuum.

Large dimensions are preferably machined by turning and milling.

The channels are preferably made with a deep drilling machine. The bores must be particularly carefully treated in order to respect a deviation with respect to the axis of maximum 0,1 millimeters for a depth of 100 millimeters. Then, the bores must be machined with an H7 tolerance (according to the ISO system), that is to say allowing a sliding assembly, to allow the introduction of a calibrated tool to achieve the two diametrically opposite grooves.

Once machining is complete, a channel partition can be inserted into each channel. For example, the channel wall consists of composite materials based on resin and glass fibers. It is for example machined by milling and is adjusted to obtain a sliding fit in the grooves of each channel. To introduce the channel partitions more easily, it is possible to use a mallet.

According to one embodiment, the grooves may be made to have a longitudinal depth slightly less than the depth of each channel so that, when the channel wall is in place, the bottom of the channel corresponds to a passage zone. between the outward and the return journey of the canal.

According to a first embodiment of the channel partitions, the distal ends of the grooves provide an axial stop for the positioning of said partition which facilitates the assembly. The channel partitions have identical dimensions in all their lengths. The lengths of the partitions are identical to the lengths of the depths of the grooves so that the upper or proximal end of each partition is flush with the surface of the connecting ring.

According to a second embodiment of the channel partitions, these have, near their proximal end, one or two shoulders. In this embodiment, the channels can be made with or without grooves. In addition, a notch is made in a groove (or both grooves, or near the opening) of each channel and on the annular region so that each shoulder rests on a notch.

According to a variant of the second embodiment, a circular machining is performed on the transverse face on which the cooling liquid channels open so as to form a circular connection groove, when the bores have not yet been made, and a succession of grooves between the openings of the bores when the bores are made.

Optionally, a hardening resin is introduced into said connection grooves or notches so as to fill them to seal between two channels. The resin is applied until it reaches the height of the proximal end of the canal walls. The resin makes it possible to improve the seal on the one hand between the inlet orifice and the outlet of each channel and secondly more generally between the crucible body and the cooling collector. The resin is preferably of the type sufficiently rigid to be machined and able to withstand the coolant. For example, the resin is Stycast® 2850FT.

In order to apply the resin, plugs obstructing the orifices of each channel are used. Preferably, each plug has a slot whose shape and thickness are complementary to the shape and thickness of the channel walls. For example, the plugs consist of PTFE polytetrafluoroethylene.

Once the resin is applied, it may be necessary to remove the excess resin by machining so as to achieve a continuous planar bearing between the proximal ends of the partitions and the resin, when connecting grooves (between each pair of channels along the around the annular region) are made, or between the proximal ends of the partitions, the resin and the surface of the annular region of the connecting ring, when notches are made.

A plane bearing along the diameter comprising the channel partitions is necessary so that a manifold partition, separating the return and return cavities from the cooling collector, bears on said flat bearing (including the channel partitions). and makes continuous contact so as to form a seal when the cooling collector is connected to the crucible body. Thus the coolant can circulate between said cooling collector and said crucible body without the coolant passing through one of the paths outside the passage provided for this purpose.

In addition, said crucible body has a second span made on the annular region of the connecting ring between the heating volume and the orifices of the channels. The second range delimits the boundary between the volume of heating and the channels. It is made so that a collector barrier comes to bear on said second range and makes a continuous contact so as to form a seal with respect to the heating volume. Preferably, the second scope is a chamfer. This characteristic has the advantage of facilitating the centering and therefore the setting in position of the cooling collector relative to the crucible body. The chamfer also has the advantage of being compact.

Preferably, each end of the collector wall and the collector barrier includes an O-ring to seal.

The manufacturing method according to the invention makes it possible to produce any type of crucible; for example straight crucibles without bottom, said "continuous casting" or both crucibles of the type "pocket" said "semi-levitation" for example hemispherical and conical.

Preferably, it is realized:

- Longitudinal cuts said "high" on the envelope through the entire thickness of the casing, the cuts extending between the connecting ring towards the end of the crucible body opposite the ring without reaching the l distal end of the crucible body,

- Longitudinal cuts called "low" by electroerosion forming slots, each slot passing through the entire thickness of the casing, being sufficiently narrow not to let escape a material to be heated, and extending in the extension of the cuts high up to the distal end opposite the connecting ring.

The slits are cut according to the following steps:

- place a nucleus inside the crucible body,

- closing the outside of the high cuts at least in their portion connecting with the slots, for example by placing an adhesive sealing tape around the envelope of the crucible body,

- fill the high cuts with resin,

- cutting the slots by electroerosion, in particular by wire,

- remove or dissolve the resin.

For example, each slot has a width of 0.35 millimeters. When cutting slots by electroerosion, it is imperative to maintain the sectors in position between them, otherwise they would deform during cutting (loosening of internal stresses in the copper).

To keep the sectors in position, a cylindrical core is inserted inside the crucible, the core being adjusted to the internal diameter of the crucible body. For example, the core is made of PTFE polytetrafluoroethylene. Preferably, the core is placed in the crucible body at level of high cuts and remote from the area where the slots will be made. Then, an adhesive tape is inserted on the outside of the crucible body opposite the core. Finally, a resin is applied in the high cuts. This implementation makes it possible to join the sectors together.

When cutting by EDM, it is essential that the wire for cutting can not come into contact with the resin, so that the cutting of the slots is not disturbed.

Once the slits are made, the resin is dissolved using a suitable solvent.

The cooling collector is preferably made in two parts. These two parts are machined separately by turning and milling and then assembled by welding. Once assembled, the collector defines two circular cavities.

Description of Figures and Embodiments

Other features and advantages of the invention will appear on reading the detailed description of implementations and non-limiting embodiments, with reference to the appended figures in which:

FIGS. 1a, 1b, 1c and 1d are views of an induction heating device comprising a "pocket" crucible connected to a cooling collector according to one embodiment of the invention, said crucible comprising longitudinal cutouts in the envelope of the crucible forming separate sectors, each sector comprising a coolant channel, FIG. 1a being a front view of said device, FIG. 1b being a sectional view of the device of FIG. longitudinal section passing through the axis of said device and by diametrically opposite cutouts, Figure 1a being a perspective view and slightly downwardly of the device according to Figure la, Figure ld being a perspective view in section of the Figure la device according to a longitudinal sectional plane passing through the axis of said device and by diametrically opposed channels; FIGS. 2a and 2b are views of a crucible showing a crucible body comprising a connecting ring and an envelope according to one embodiment of the invention, according to FIGS. 1a-1d, FIG. 2a being a front view. crucible body, Figure 2b being a sectional view of a crucible body according to Figure 2a in a longitudinal sectional plane passing through the axis of said crucible body and diametrically opposed cutouts;

FIG. 3 is a sectional view of a crucible body according to FIG. 2a in a section with perpendicular planes whose first plane passes through the axis and through diametrically opposite cutouts of the crucible body and the second plane of which passes through the envelope, FIG. 3 showing in particular sectors separated from the envelope, each sector comprising a channel according to one embodiment of the invention,

- Figure 4 is an enlargement of a portion of the connecting ring of the crucible body of Figure 2b, showing a portion of an annular region of said ring, said region comprising a connecting groove;

- Figure 5 is an enlargement of a sector seen in section of Figure 3, showing cutouts at the bottom of the crucible body;

- Figure 6a is a sectional view of a crucible body according to Figure 2a in a longitudinal sectional plane passing through the axis of said crucible body and by diametrically opposed channels, a reported channel partition being visible in each channel;

FIG. 6b shows an example of an attached channel partition seen from the front;

FIGS. 7a, 7b show a first tubular part of the cooling collector according to one embodiment, intended to be connected to a second part of said collector, FIG. 7a being a front view of said first part, FIG. 7b being a sectional view of the part of Figure 7a showing a bore for the passage of the materials to be heated;

Fig. 8 is a sectional view of a second part of the cooling manifold including a manifold partition, a coolant inlet and a coolant outlet; FIG. 9 is a perspective view of a crucible body comprising coolant channels into which inserted channel partitions are inserted whose proximal ends are visible;

FIG. 10 is a perspective view of a channel plug according to one embodiment, the plug including a slot for receiving a proximal end of an attached channel septum;

FIGS. 11a and 11b show a "bottomless" crucible body, according to one embodiment, comprising a connecting ring and an envelope, FIG. 11a being a front view, FIG. 11b being a sectional view of crucible body of Figure 11a according to a cutting plane passing through the axis and diametrically opposite cutouts of the crucible body;

- Figure 12 an enlargement of an induction heating device seen in section of Figure ld, showing the communication of the coolant between the cooling collector and the body of the crucible.

Description of an exemplary embodiment

The embodiments which will be described hereinafter are in no way limiting; it will be possible in particular to implement variants of the invention comprising only a selection of characteristics described hereinafter isolated from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention compared in the state of the prior art. This selection comprises at least one feature preferably functional without structural details, or with only a part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art.

In particular, all the variants and all the embodiments described are combinable with each other if nothing stands in the way of this combination at the technical level.

Figs. 1a, 1b, 1c and 1d illustrate an induction heater 1 for melting materials to make alloys or melting pure metals to make castings in molds, or refine in a particular atmosphere during melting. The heating device comprises a so-called "cold" crucible 10 for containing said materials to be heated, also called "the load" (not visible in the figures). The charge is heated by a wound inductor (not shown) around the crucible 10 and a generator (not shown). In known manner, the heating device also comprises a cooling collector 30 distributing a cooling liquid in the crucible 10 connected to the latter.

First, a crucible 10 of the "pocket" or "semi-levitation" type will be described. Referring to Figures 1a, 1b, 1d, 2a, 2b, 6a and 9, the crucible 10 comprises a crucible body 11 containing the material to be heated.

The crucible body 11 comprises a connecting ring 12 intended to allow the connection of a mechanical part and secondly of the coolant flows between the crucible body and the cooling collector. The connecting ring is a circular portion of the crucible body and is continuous material along its circumference. The connecting ring will be described in more detail later.

The crucible body 11 comprises a tubular casing 14 extending axially from the connecting ring 12 to define a heating volume. The crucible body comprises sectors 16 made in the tubular envelope 14. The crucible body 11 has a one-piece structure composed of a single material having a continuity of material between the connecting ring 12 and the sectors 16 of the crucible. the tubular casing 14, including them. In the case of a crucible of the "pocket" or "semi-levitation" type, the crucible body 11 comprises a crucible bottom 110 that is substantially conical. The casing 14 is cut longitudinally so as to produce several separate sectors 16. With reference to FIGS. 1b, 2b, 3 and 5, so-called "high" or interstice longitudinal cuts 18 are made in radial directions with respect to the axis longitudinally of the crucible body and in the thickness of the tubular casing 14 so that the remaining shell portions form angular shell sectors along the circumference of the casing the envelope 14 (see in particular Figures 3 and 5). With reference to FIGS. 1b, 2b and 3, the longitudinal cuts 18 are made with a transverse depth equal to the distal end of the crucible body so that the bottom 110 of the crucible body is not cut off all over its body. thickness but in a cutout having a width that may be substantially identical to the width of a cutout 18; since the bottom of the crucible 110 is conical. According to another embodiment, the cutting width at the bottom 110 of the crucible body may be slightly different, either to increase the efficiency of the crucible or to improve cooling.

The high cuts 18 have a width substantially equal to 3 to 4 millimeters. This makes it possible to limit the losses of charges especially in the case of realization under vacuum.

The bottom of the crucible 110 also has longitudinal cuts. With reference to FIGS. 1b, 2b and 5, longitudinal cuts or slots 19 are made in directions radial with respect to the longitudinal axis of the crucible body and in the thickness of the bottom of the crucible body 110 so that the portions Remaining body bottoms form angular sectors of envelope along the circumference of the bottom 110 of the crucible body. The slots 19 are made substantially in the extension of the upper cutouts 18 so that the sectors 16 are separated from the connecting ring to the distal end of the crucible body. The slots 19 have a width substantially equal to 0.35 millimeter.

According to the example shown, the crucible body has an inner diameter of 50 millimeters and comprises 16 sectors. The crucible body shown in FIGS. 1b, 1d, 2b and 6a has, at its distal end, a casting opening 111 making it possible to cast the charge by gravity in an ingot mold located below. In use, a retractable finger (not shown) obstructs the end of the crucible body, for example a finger itself cooled.

The crucible body comprises a coolant channel 15 in each sector 16. Referring to Figures 1d, 3 and 6a, each cooling channel 15 is longitudinally disposed in the thickness of each sector. The channels 15 have a tubular shape. With reference to FIGS. 1d and 6a, the channels 15 extend to the bottom of the crucible body 110 so as to form a blind hole whose bottom called the channel bottom is designated by the reference 151. With reference to FIGS. 6a, the channels 15 open onto the upper surface of the connecting ring 12 comprising an annular region 120. The annular region 120 forms a continuous portion formed in the material of the one-piece crucible body.

The crucible body comprises a plurality of channel partitions 20 so that each partition is provided to be inserted into a channel 15. In addition, each channel 15 is arranged and configured to receive a channel partition 20. It is inserted longitudinally into each channel and forms a tight longitudinal contact with at least two distinct regions of the peripheral inner wall of said channel. From the bottom view of the channel 151, the distal end of the channel septum 20 is remote from the channel bottom 151 so as to leave a passage. For example, the width of the passage is substantially equal to the radius of the channel. Once inserted in a channel and with reference to FIGS. 6a and 12, each channel 15 has inside it and on both sides of the channel partition 20 a so-called "go" path 22 and a so-called "return" path 21 for the circulation of the coolant in each sector of the crucible body. The coolant can flow from the forward path to the return path through the passage, provided for this purpose, near the bottom of the channel 151. On the side of the connecting ring (see Figure 3 left side, 2b, 11b ), the paths open into the annular region 120. For each channel 15, the annular region has an "inlet" orifice 24, corresponding to the input of a forward path 22, and an "outlet" orifice. 23, corresponding to the exit of a return path 21. The inlet and outlet orifices 24 and 23 must be arranged next to each other and aligned along a radial direction of the crucible.

As can be seen, especially in FIGS. 3 and 6a, each channel 15 has an inlet orifice 24 and an outlet orifice 23 which are formed by the same opening of the channel 15 opening into the annular portion. It is this common opening which is itself divided into an inlet opening 24 and an outlet opening 23 through the proximal end 200 of the channel partition 20. The set of these openings opening each a channel 15 is distributed in a single circle corresponding to the annular region 120.

According to a preferred embodiment, each channel further has two diametrically opposed grooves so as to receive and position each channel partition 20. The grooves form two distinct regions extending longitudinally in each channel and form a tight longitudinal contact with the partition channel 20 inserted in said channel.

The reported channel partitions have a rectangular shape whose thickness is much smaller than its length or width so that they respectively form a plane. Referring to Figure 6b, the channel wall 20 has at its proximal end, intended to be close to the connecting ring, a width widening 210 forming a shoulder. The widening width 210 is provided to bear against a notch made on the surface of the annular region 120. Preferably, two diametrically opposite notches are formed on the annular region 120 to receive the shoulders of the channel walls.

With reference to FIGS. 3 and 9, each channel wall 20 is disposed in its channel 15 so that an imaginary geometric plane included in the thickness of the partition is substantially tangential to a cylinder of imaginary revolution concentric with the crucible. This characteristic makes it possible to radially delimit two coolant distribution regions, a first coolant inlet region comprising all the inlet orifices 24 and a second coolant return region comprising all the outlet orifices 23 It is then possible to connect a cooling collector having no indexing for example angular to connect the flow of inlet and outlet coolant between the cooling collector and the crucible body.

Referring to Figures 2b, 3 and 4, the annular region 120 includes a plurality of connection grooves 121 connecting the channel openings, or notches provided for the channel partitions, so as to form a circular groove. The connecting grooves 121 are intended to be filled with resin producing a seal radially delimiting, with the proximal ends 200 of the channel walls, the two regions coolant distribution. With reference to FIGS. 9 and 10, the orifices of the cooling channels are plugged by plugs 40 (see FIG. 9 showing a plug blocking a channel). Each plug 40 has a substantially cylindrical outer shape whose outer diameter is substantially equal to the inner diameter of each channel. Each plug 40 comprises a partition slot 41 for receiving a proximal end of a channel wall (see FIG. 10), thereby allowing the plug to be inserted into the channel comprising a partition so as to plug the orifices of the channel. Once the channels are closed, the connection grooves 121 are filled with resin. Once the resin has hardened, the plugs 40 are removed and the excess resin is removed, for example by machining, in order to obtain a plane bearing and thus serve as a junction surface with a circular partition of the cooling collector. Preferably, the embodiment of the planar scope may include machining the proximal end of the channel partitions.

Referring to Figures 2a, 2b, 6a, the connecting ring 12 has on its periphery a connecting surface 13 comprising a crucible thread arranged to allow a screw connection with a cooling manifold comprising a complementary collector thread of that the crucible can be screwed on a collector or vice versa.

Figures 11a and 11b shows another type of crucible said "bottomless" or "continuous casting". In this embodiment, the crucible body does not have a conical crucible bottom 110, but has a heating volume having a constant internal diameter to the end of the crucible body. For the rest, the crucible body of Figures 11a and 11b includes the same characteristics as a crucible called "pocket" or "semi-levitation" as described in the other figures.

We will now describe a cooling collector 30 arranged and configured to be connected both mechanically and with respect to the circulation of coolant flows between said collector and a crucible body described above. From a mechanical point of view and in Referring to Figure 8, the cooling collector comprises a first peripheral portion 30a which has on an inner face a manifold thread 31 complementary to the crucible thread so that they can be assembled by screwing.

With reference to FIGS. 1b and 12, the cooling collector 30 comprises two collector cavities forming the distribution elements: a so-called "go" cavity 34 and a so-called "return" cavity 33 which are substantially circular and which are arranged opposite the annular region 120 of the connecting ring. The cavities 33, 34 are offset in a radial direction relative to the axis of the manifold so that the forward cavity 34 is opposite the inlet ports 24, and the return cavity 33 is opposite the outlet orifices 23. The cavities 33, 34 are separated by a circular manifold partition 32. The manifold partition 32 is provided to abut against the proximal ends called "sealing" 200 of the channel walls (see Figures lb and 12). Referring to Figs. 1b, 1d and 12, the manifold partition 32 has a conical shape.

The manifold also includes a coolant inlet port 38 communicating with the forward cavity 34, and a coolant outlet port 37 communicating with the return cavity 33 (see Figs. 1b and 8). The return cavity 33 is delimited radially by the collector partition 32 and by an internal rim 123 of the connecting ring 12 (see FIGS. 1b and 12).

Referring to Figures 7a, 7b, the manifold includes a second manifold part 30b which comprises a tube 35 whose upper end comprises a flange 350. The volume defined by the tube 35 corresponds to an insertion passage 36 via which the charge is inserted before being introduced into the heating volume defined by the tubular casing (Figures lb and ld). The second collector part 30b is intended to be welded to the first collector part 30a (see FIG. 8). Preferably, the first manifold part 30a comprises a counterbore 301 on its upper end. The cooling manifold is made by welding the collar 350 of the second manifold part 30b into the counterbore 301 of the first manifold part 30a, so as to obtain the cooling manifold 30 shown in Figs. 1b and 1d. The forward cavity 34 is thus delimited radially by the collector partition 32 and by the wall of the tube 35, see FIG. 12.

With reference to FIG. 12, once the cooling collector 30 is connected to the crucible body 11, the collector wall 32 presses on the proximal ends of the channel walls and the sealant resin, and the tube 35 presses on a chamfer 124 made on the annular region 120.

With reference to FIGS. 1b and 1d, the collector 30 is arranged concentrically with respect to the crucible body 11. The cooling collector 30 comprises an insertion passage 36 through which the charge is inserted before being introduced into the volume heating defined by the tubular casing.

Claims

claims

1. Cold crucible (10) for induction heating device (1),

characterized in that it comprises a crucible body (11) comprising:

a connecting ring (12) comprising an annular distribution region (120),

a tubular casing (14) extending from the connecting ring (12) to define a heating volume, the casing being cut longitudinally so as to form several separate sectors (16),

coolant channels (15) arranged longitudinally in the thickness of the crucible body such that each sector (16) comprises at least one coolant channel (15),

each sector comprising at least two coolant paths, a forward path (22) and a return path (21) of the coolant, formed by the at least one coolant channel (15), said paths leading to the annular distribution region (120) so that said region (120) has, for each sector, an inlet (24) and an outlet (23), the orifices being spaced apart from each other along a radial direction of the crucible,

thus forming along the periphery of the annular distribution region two distinct concentric regions around the longitudinal axis of the crucible, one of which communicates only with the forward path of the channels and the other communicates only with the return path of the channels,

the crucible body being adapted to be removably assembled with a cooling collector (30) via the connecting ring (12), the collector (30) comprising coolant distribution elements connecting to the liquid channels cooling device (15), because of this assembly, for circulating said liquid between the collector and the channels, and in that said crucible body (11) has a one-piece structure made of a single material having a continuity of material on at least two sectors.

Crucible (10) according to claim 1, characterized in that each channel comprises an attached channel partition (20) inserted longitudinally in said channel (15) and forming a tight longitudinal contact with at least two distinct regions of the peripheral wall said channel, so as to define the forward path (22) and the return path (21) on either side of said partition (20) and extending longitudinally within the same channel (15).

Crucible (10) according to claim 2, characterized in that each channel partition (20) has a planar or two-dimensional shape and is arranged in its channel (15) so that an imaginary geometrical plane included in the thickness of the partition is substantially tangential to a cylinder of imaginary revolution concentric to the crucible.

4. Crucible (10) according to claim 2 or 3, characterized in that each channel partition (20) has a length substantially equal to or less than the length of the channels, and is intended to be inserted into a channel leaving a gap nonzero between the bottom (151) of the channel and the longitudinal end of said channel wall passage.

5. Crucible (10) according to one of claims 2 to 4, characterized in that each channel (15) comprises in its wall two separate grooves arranged and configured to receive and position each partition (20) in said channel.

6. Crucible (10) according to any one of the preceding claims, characterized in that the connecting ring (12) comprises on its periphery a crucible thread (13) arranged to allow a screw connection so that a cooling collector (30) provided with a collector thread (31) which is complementary thereto can be screwed on the crucible or vice versa.

7. Cooling collector (30) for cooperating with a cold crucible (10) for an induction heating device (1), the crucible comprising:

a connecting ring (12) comprising an annular distribution region (120),

coolant channels (15) arranged longitudinally in the crucible thickness such that each sector (16) comprises at least one coolant channel comprising a channel partition (20) forming in each channel at least two paths (21, 22) opening respectively by two orifices (23, 24) spaced apart from one another along a radial direction of the crucible,

the collector being characterized in that it has two cavities (33, 34) of collector which are substantially circular and are arranged on the same face coming opposite the connecting ring, the collector cavities being offset in a radial direction relative to the collector axis such that each collector cavity (33, 34) is located above a single orifice (23, 24) of each channel after the collector and the crucible are assembled .

8. Manifold (30) according to the preceding claim, characterized in that it comprises a circular manifold partition (32) separating said two collector cavities (33, 34), said collector partition (32) abutting against so-called sealing ends (200) of the channel partitions.

9. Manifold (30) according to claim 7 or 8, characterized in that it comprises, around the collector cavities, a collector thread (31) arranged to allow a screw connection so that a crucible body ( 10) also comprising a complementary crucible thread (13) which can be screwed onto the collector (30) or vice versa.

Induction heating device (1) comprising a cold crucible body (10) according to one of claims 1 to 6 and a cooling collector (30) according to one of claims 7 to 9 arranged so that, when they are assembled together, the coolant distribution elements (33, 34) of the manifold (30) are connected to the coolant channels (15) of the crucible body (10).

11. A method of manufacturing a cold crucible (10) for an induction heating device, the crucible comprising a crucible body (11) communicating with a cooling collector (30), the crucible body comprising a tubular envelope (14). ) extending from the cooling collector and surrounding a heating chamber included in a heating volume, the casing being cut longitudinally so as to provide a plurality of separate sectors (16), longitudinally disposed coolant channels (15). in the thickness of the crucible so that each sector (16) comprises at least one coolant channel (15), the method comprising the following steps:

providing one or more monoblock starting pieces or blanks, made of a thermally and electrically conductive material, preferably of copper, for example a solid round or a tube,

for each starting piece, machining the part with the desired external and internal dimensions, according to the desired crucible size, to produce a crucible body forming a connecting ring from which the tubular envelope extends,

as well as, in this order or in another, the following steps:

making a crucible thread (13) on the periphery of the connecting ring (12),

producing bores corresponding to the coolant channels (15) and opening into the surface of the connecting ring (12),

making two diametrically opposite grooves in the wall of each channel (15), making longitudinal cuts (18, 19) on the envelope (14) through the entire thickness of the envelope, the cuts extending between the connecting ring (12) and to the end of the body crucible opposite to the ring.

12. Method according to claim 11, characterized in that a circular machining is performed on the transverse face on which the channels open to form a circular connection groove (121), when the bores have not yet been made, and a succession of grooves (121) between the openings of the bores when the bores are made, and in that a hardening resin is introduced into the grooves (121) so as to fill them to seal between two channels.

13. The method of claim 11 or 12, characterized in that introduces a channel wall in each channel after making the grooves.

14. Process according to one of Claims 11 to 13, characterized in that:

longitudinal cuts said "high" (18) on the casing (14) through the entire thickness of the casing, the cuts extending between the connecting ring (12) to the end of the crucible body opposite to the ring without reaching the distal end of the crucible body,

longitudinal cuts called "low" by electroerosion forming slits (19), each slot passing through the entire thickness of the envelope, being sufficiently narrow not to let escape a material to be heated, and extending in the extension high cuts (18) to the distal end opposite the connecting ring.

15. Method according to the preceding claim, characterized in that the cutting slits (19) is performed according to the following steps:

placing a core inside the crucible body (11), closing the outside of the high cutouts at least in their portion connecting with the slots, for example by placing an adhesive sealing tape around the envelope of the crucible body, filling the high cuts with resin,

- cutting the slots by electroerosion, in particular by wire,

remove or dissolve the resin.