EP3191240B1

EP3191240B1 - Cooling device for ingot molds adapted to produce ingots and bars of precious metal

Info

Publication number: EP3191240B1
Application number: EP15760376.2A
Authority: EP
Inventors: Giovanni FAORO
Original assignee: Ikoi SpA
Current assignee: Ikoi SpA
Priority date: 2014-09-10
Filing date: 2015-09-07
Publication date: 2018-08-22
Anticipated expiration: 2035-09-07
Also published as: WO2016037695A1; EP3191240A1

Description

The present invention relates to a cooling device for ingot molds, particularly adapted to produce ingots and bars of precious metal.
In the production process of ingots, particularly ingots of precious metal, it is known to use continuous-cycle systems also known as tunnel type furnaces, in which the metals are cast inside graphite ingot molds that are heated by electromagnetic induction or another means.
At the outlet of the casting region, the temperature of the ingot molds is then lowered, in a controlled manner, until the ingots solidify and cool completely.
In currently commercially available systems, heat removal occurs by means of adapted devices that have a cooling surface that is cooled by water by virtue of passage holes that are provided inside it The cooling surface is made of copper, aluminum, or other materials suitable for controlled heat dissipation.
Generally, the ingot molds remain above the cooling surfaces for a preset time as a function of the amount of material to be solidified, until the entire mass solidifies.
Although the conventional cooling devices substantially achieve their purpose, in some cases the need is felt to modify their normal cooling dynamics, creating a minimum distance between the bottom of each ingot mold and the cooling surface.
In this regard, the bottom of the ingot molds is often milled so as to create a step along the entire perimeter of the bottom.
However, such system is onerous in terms of time and cost, because it entails an additional step of machining in the production of the ingot molds.
It should also be considered that, after a few cycles of use, the milling tends to wear, returning the ingot mold to the original state, unless it is milled again, but this would require additional time and costs.
WO2012130451 (A1 ) discloses a machine for forming metal bars, in particular suitable for melting and the subsequent continuous solidification of a precious metal such as gold, silver, precious alloys, as well as other pure metals or different alloys, in form of powder, grits or swarf of various sizes, for producing ingots having weight varying from 50 g to 50 kg. In particular such machine has six operating stations (101 - 106), arranged in succession. A solidification station includes a cooling surface supporting the ingot molds.
The aim of the invention is therefore to provide a cooling device, particularly for ingot molds adopted to produce ingots and bars of precious metal, that solves the problems of the cited prior art.
Within the scope of this aim, a particular object of the invention is to provide a
cooling device that allows to control the temperature reduction without intervening with modifications on the ingot mold itself.
Another object of the invention is to provide a cooling device that allows to cool localized portions of the bottom of each ingot mold.
Another object of the invention is to provide a cooling device which, by virtue of its particular constructive characteristics, is capable of giving the greatest assurances of reliability and safety in use.
A further object of the invention is to provide a cooling device that allows to maximize productivity, at the same time ensuring maximum product quality.
Another object of the invention is to provide a cooling device that requires reduced and simplified maintenance.
This aim, these objects and others that will become better apparent hereinafter are achieved by a cooling device for ingot molds, adapted for the production of ingots and bars of precious metal, comprising a cooling means that forms a heat extraction surface on which at least one ingot mold is to be placed; said heat extraction surface lying on a first substantially horizontal plane; said device being characterized in that it comprises a supporting means that forms a resting surface of said ingot mold; said resting surface lying on a second substantially horizontal plane; said supporting means and said cooling means being relatively mutually movable so as to reversibly pass from a sliding condition, in which said first plane and said second plane are substantially parallel and coincide, to a controlled cooling condition, in which said first plane and said second plane are substantially parallel and distinct.
Further characteristics and advantages will become better apparent from the description of preferred but not exclusive embodiments of a cooling device according to the invention, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a partially sectioned perspective view of a cooling device according to the invention;
Figure 2 is a front section view of the cooling device;
Figure 3 is a perspective view of the cooling device according to the invention;
Figure 4 is a longitudinally sectioned view of the cooling device according to the invention;
Figure 5 is a perspective view of a detail of the cooling device according to the invention.

With reference to the cited figures, a cooling device, particularly for ingot molds adapted to produce ingots and bars of precious metal, is designated generally by the reference numeral 1.
Merely by way of indication, the cooling device 1 might be inserted in a system for the continuous production of precious metal ingots, or in a so-called tunnel-type furnace, which is not described here since it is per se known.
However, it is important to point out that the present invention can be also used in combination with production lines and machines of a different type.
According to a preferred embodiment, the cooling device 1 is structured so as to receive in input one or more ingot molds, which proceed along a preset advancement direction and stop temporarily in a preset region, where at least their lower resting surface is cooled.
The cooling device 1 has a cooling means 2 provided with a heat extraction surface 3, on which the ingot molds are to be placed during cooling.
The cooling means 2 is constituted by a plate-shaped cooling member 4.
Advantageously, the cooling member 4 is made of a heat conducting material, such as for example copper, aluminum or other material having sufficient heat conductivity.
In practice, the heat extraction surface 3 coincides with the upper face of the cooling member 4 and lies on a first substantially horizontal plane.
Thermally insulated walls 50 may be arranged at the sides of the cooling member 4.
Conveniently, the thermally insulated walls 50 limit any outward heat dispersions on the part of the ingot mold that is cooling and therefore allow to maximize the action of the cooling member 4.
In the illustrated embodiment, the heat extraction surface 3 is flat and smooth so as to be able to make full contact with the lower resting surface of each ingot mold.
According to a further embodiment of the invention, the heat extraction surface 3 is provided with protruding dissipation portions adapted to make contact with corresponding portions of the lower resting surface of each ingot mold.
Conveniently, the cooling member 4 is associated with a first means for extracting the heat of the ingot molds.
The first heat extraction means consists of a first hydraulic circuit 5 within which a heat transfer fluid is made to flow and extracts the heat from the ingot molds and transfers the heat out of the cooling member 4.
The first hydraulic circuit 5 extends within the cooling member 4, within the transverse thickness of the plate, according to a preset path.
The cooling member 4 is also provided with at least one pair of hydraulic connectors 6 and 7 arranged at the ends of the hydraulic circuit, so as to form respectively its inlet point and its outlet point.
Preferably, the hydraulic connectors 6 and 7 are provided at the ends of the cooling member 4 and provide a hydraulic connection between the first hydraulic circuit 5 and a distribution circuit.
According to the present invention, the cooling device 1 has a supporting means 10, which forms a resting surface 11 for each ingot mold during cooling.
The resting surface 11 lies on a second substantially horizontal ideal plane.
According to a further aspect of the present invention, the supporting means 10 and the cooling means 2 move with respect to each other so as to be able to reversibly pass from a sliding condition, in which the planes of arrangement of the heat extraction surface 3 and of the resting surface 11 are substantially parallel and coincident, to a controlled cooling condition, in which the two planes are substantially parallel and distinct.
In the case given by way of example, the supporting means 10 comprises one or more column-shaped supporting members 12, which are fixed to a framework 13.
The supporting members 12 are slidingly arranged within a corresponding number of holes 8 provided thereat on the cooling member 4.
In practice, the free end of the supporting members 12 defines the resting surface 11.
In the sliding condition, the free end of the supporting members 12 is substantially flush with the upper surface of the cooling member 4.
Instead, in the controlled cooling condition, the free end of the supporting members 12 protrudes from the upper surface of the cooling member 4, so that the ingot mold that is cooling is slightly raised with respect to the cooling member 4 yet it is closely proximate thereto.
In the illustrated example, eight supporting members 12 are arranged substantially at the edges of the lower resting surface of the ingot mold being cooled.
Four supporting members 12 are arranged substantially at the corners of the rectangular base of the ingot mold being cooled, while the other four supporting members 12 are equally distributed along the longer sides of the base.
According to a further aspect of the invention, a single supporting member 12 is arranged substantially at the center of the rectangular base of the ingot mold that is cooling.
According to a further aspect of the invention, each supporting member 12 is associated with a second heat extraction means, not shown in the figures.
The second heat extraction means may be constituted, for example, by a second hydraulic circuit in which a heat transfer fluid is made to flow and extracts the heat from the ingot molds and transfers it out of the supporting members 12.
Advantageously, the second hydraulic circuit extends within each supporting member 12 and is connected to the already cited distribution circuit.
Placing a single supporting member 12 at the center of the rectangular base of the ingot mold being cooled and lowering its temperature can be particularly important to ensure maximum quality of the surfaces of the finished ingot.
Experimental tests and careful analysis of the results have in fact allowed to observe that, the step of inducing the cooling to propagate from the center of the ingot mold owards its ends, leads to a uniform and even distribution of any oxides and residues throughout the ingot.
In this regard, it should be considered that in the prior art cooling devices the last point to be cooled is substantially the center of the ingot mold, and this is indeed where any oxides and residues usually tend to accumulate.
In the illustrated embodiment of the present invention, the relative motion between the cooling means 2 and the supporting means 10 occurs by keeping the latter fixed and by moving the cooling member 4.
While the supporting means 10 is coupled to a footing 100, the cooling member 4 is associated with a movement means, which actuates its vertical movement, so as to allow it to pass from the sliding condition to the controlled cooling condition and vice versa.
According to an embodiment of the invention, the movement means comprises two pairs of double-acting pneumatic cylinders 14, which are arranged substantially at the two axial ends of the cooling member 4.
The pneumatic cylinders 14 of each pair have their body associated with the footing 100 and the end of the stem 15 joined to a cross-member 16 that is fixed to the lower face of the cooling member 4.
Each cross-member 16 has such a length that the pneumatic cylinders 14 associated therewith are external to the volume occupied by the cooling member 4.
In the specific case, i.e. when the thermally insulated walls 50 are present laterally to the cooling member 4, the length of the cross-member 16 must also take into account the thickness of the walls.
This allows to provide pairs of sliders 17 above each cross-member 16, the sliders 17 can slide on the outer face of the thermally insulated walls 50 so as to guide the vertical movement of the cooling member 4.
According to a further aspect of the invention, the above described pneumatic members may be replaced with adapted mechanisms, such as for example mechanisms of the cam type or of the screw type, which are not described since they are per se known.
A mechanical stroke limiter 18 allows to adjust the maximum movement allowed between the planes of arrangement of the heat extraction surface 3 and of the resting surface 11.
In the specific case, the mechanical stroke limiter 18 is constituted by a screw with a nut and a lock nut inserted in a female thread provided in a turret 19 that rises from the footing 100.
The cooling device 1 is also provided with a shock absorbing system formed by shock absorbers 20 that damp the oscillations of the cooling member 4.
According to an embodiment of the invention, the relative motion between the cooling means 2 and the supporting means 10 occurs by moving the latter and keeping the cooling member 4 stationary.
In this case, it is the cooling member 4 that is coupled to the footing 100, while the supporting means 10 is associated with a movement means that actuates its vertical movement, so as to allow in any case the transition from the sliding condition to the controlled cooling condition and vice versa.
The movement means is substantially equivalent to the means already described in the previous case.
According to a further embodiment of the invention, not shown in the figures, the cooling means 2 is constituted by a series of cooling members that are mutually combined and are arranged at predefined specific points.
Likewise, the supporting means 10 is constituted by a series of mutually matched supporting members which are arranged, in this case also, at predefined specific points.
Advantageously, the positioning points can be identified for example by virtue of the dot matrix method.
This configuration allows to move the cooling members with respect to the supporting members and vice versa selectively.
In practice, in this manner it is possible to give the heat extraction surface 3 and the resting surface 11 the shapes that are most suited for the specific case, even cooling localized portions of the bottom of each ingot mold.
Regardless of its configuration, the operation of the cooling device according to the invention is in any case simple and intuitive.
In the illustrated example, the ingot mold to be cooled is pushed above the cooling member 4 and when the corners of its resting base are substantially at the supporting members 12 that are furthest apart its stroke is stopped.
At this point the movement means is activated and transition from the sliding condition to the controlled cooling condition occurs.
In practice, if the cooling member 4 is moved, it is lowered vertically until it reaches the level set by the mechanical stroke limiter 18.
In this manner, the end portion of the supporting members 12 protrudes from the upper surface of the cooling member 4 so as to create a minimum spacing between the ingot mold and the cooling member 4 while keeping them closely proximate.
Likewise, if the cooling member 4 is fixed, the supporting means 10 is raised, obtaining substantially the same result described above.
It is important to note that the distance between the heat extraction surface 3 and the resting surface 11 can be changed in each instance or even during cooling, so as to control the temperature in the best possible way during the process.
Once the cooling operation has ended, the cooling device 1 returns to the sliding condition and the ingot mold continues along its initial advancement direction, leaving room for another ingot mold to be cooled.
The cooling device 1 therefore allows to control the cooling of each ingot mold, varying the distance between the heat extraction surface 3 and the resting surface 11, and in an extreme case also allows to cool localized portions of the bottom of the ingot mold without modifying its geometries.
Therefore, this solution allows to maximize productivity, ensuring at the same time the maximum quality of the finished product.
The cooling device 1 according to the invention is reliable and safe and also requires a limited and simplified maintenance.
In practice it has been found that the cooling device, particularly for ingot molds adapted to produce ingots and bars of precious metal, according to the invention, achieves fully the intended aim.
In practice, the materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.

Claims

A cooling device for ingot molds, adapted for the production of ingots and bars of precious metal, comprising a cooling means (2) that forms a heat extraction surface (3) on which at least one ingot mold is to be placed; said heat extraction surface (3) lying on a first substantially horizontal plane; said device being characterized in that it comprises a supporting means (10) that forms a resting surface (11) of said ingot mold; said resting surface (11) lying on a second substantially horizontal plane; said supporting means (10) and said cooling means (2) being relatively mutually movable so as to reversibly pass from a sliding condition, in which said first plane and said second plane are substantially parallel and coincide, to a controlled cooling condition, in which said first plane and said second plane are substantially parallel and distinct.
The cooling device according to claim 1, characterized in that said cooling means (2) comprises one or more cooling members made of thermally conductive material, said cooling members being associated with a first heat extraction means (5) for extracting the heat of said ingot mold; said cooling members being shaped and arranged so as to form said heat extraction surface (3).
The cooling device according to claim 2, characterized in that said cooling means (2) comprises a single cooling member (4) formed as a plate.
The cooling device according to claim 1, characterized in that said cooling means (2) comprises a plurality of mutually combined cooling members, which are arranged at predefined points; said cooling members being selectively movable with respect to said supporting means (10).
The cooling device according to claim 2, characterized in that each of said cooling members (4) is provided with protruding dissipation portions that are adapted to define said heat extraction surface (3).
The cooling device according to claim 2, characterized in that said first heat extraction means comprises a first hydraulic circuit (5) in which a heat transfer fluid flows; said first hydraulic circuit (5) being provided within the thickness of said cooling members (4).
The cooling device according to claim 1, characterized in that said supporting means (10) comprises one or more supporting members (12) fixed to a framework (13); said supporting elements (12) being shaped and arranged so as to define said resting surface (11).
The cooling device according to claim 3, characterized in that said supporting means (10) comprises at least four supporting members (12) that are substantially column-shaped and are arranged substantially at the edges of the lower resting surface of said ingot mold; said supporting elements (12) being slidingly arranged within corresponding holes (8) provided in said plate cooling member (4).
The cooling device according to claim 3, characterized in that said supporting means (12) comprises a single supporting member that is substantially column-shaped and is arranged substantially at the center of the lower resting surface of said ingot mold; said supporting member being slidingly arranged within a corresponding hole (8) provided in said plate cooling member (4).
The cooling device according to claim 1, characterized in that said supporting means comprises a plurality of mutually combined supporting members arranged at predefined points; said supporting members being selectively movable with respect to said cooling means.
The cooling device according to claim 7, characterized in that each one of said supporting members comprises a second means for extracting the heat of said ingot mold.
The cooling device according to claim 11, characterized in that said second heat extraction means comprises a second hydraulic circuit in which a heat transfer fluid flows; said second hydraulic circuit being provided within the thickness of said supporting members.
The cooling device according to claim 2, characterized in that it comprises a means for moving said cooling members; said cooling members being movable in a substantially vertical direction in order to pass from said sliding condition to said controlled cooling condition and vice versa.
The cooling device according to claim 7, characterized in that it comprises a movement means for moving said framework; said framework and said supporting members being movable in a substantially vertical direction to pass from said sliding condition to said controlled cooling condition and vice versa.
The cooling device according to claim 14, characterized in that said movement means comprises at least one hydro-pneumatic member that interacts with said cooling members and with said framework.
The cooling device according to claim 14, characterized in that said movement means comprises a kinematic means that interacts with said cooling members and with said framework.
The cooling device according to claim 14, characterized in that said movement means comprises an adjustable stroke limiter device, which is adapted to adjust the maximum movement allowed between said two planes.
The cooling device according to claim 14, characterized in that said movement means comprises a shock absorbing system that is adapted to damp the oscillations of said two planes.