Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/02—Induction heating
  • H05B6/10—Induction heating apparatus, other than furnaces, for specific applications
  • H05B6/101—Induction heating apparatus, other than furnaces, for specific applications for local heating of metal pieces
  • H05B6/103—Induction heating apparatus, other than furnaces, for specific applications for local heating of metal pieces multiple metal pieces successively being moved close to the inductor
  • H05B6/104—Induction heating apparatus, other than furnaces, for specific applications for local heating of metal pieces multiple metal pieces successively being moved close to the inductor metal pieces being elongated like wires or bands

Definitions

• the present invention regards a magnetic induction furnace suitable to heat at least one metal billet, solid or tubular, made of non-ferrous material to be subjected to extrusion, according to the preamble of the main claim .
• induction furnace for heating billets arranged vertically with respect to a plane for supporting the device or the aforementioned furnace.
• the billet is subjected to movement during the heating thereof, said movement possibly rotating around the axis thereof and/or longitudinal along such axis.
• This with the aim of obtaining uniform temperature distribution along the aforementioned axis, between the ends of the billet.
• This necessarily requires having means suitable to rotate or generate such axial movement of the billet, thus complicating the manufacturing of the furnace and increasing the costs thereof.
• the axial movement of the billet into and out of the furnace or with the possibility of projecting therefrom during the displacement entails a continuous heating and subsequent cooling of the end of the billet (with considerable waste of energy) , while the central part - still submerged in the variable or rotary magnetic field of the furnace, has temperatures that are high and greater than those of the end. This may negatively affect the extrusion operation to which the billet is subjected subsequently.
• the means movably supporting the billet during the movement are also subjected to heating that could damage them over time.
• the object - in the heating step - is subjected to movement (rotary or axial) in the furnace, were such object to be made up of several parts arranged axially adjacent and consecutive to each other, the ends of such parts at contact must be necessarily machined so as to suitably arrange them one on the other without the possibility of mutual displacement during the movement thereof.
• the parts of the object undergoing heating could end up arranged with longitudinal axes not coaxial to each other, relatively inclining with the possibility of impacting the walls of the compartment in which they are arranged, the walls being defined by the rotor with the permanent magnets or filtering means interposed between such rotor/s and the aforementioned object.
• An object of the present invention is to provide a magnetic induction furnace for heating metal billets, solid or tubular, made of non-ferrous material (such as for example aluminium) to be subjected to extrusion that is improved with respect to the prior art furnaces.
• an object of the invention is to provide a furnace of the aforementioned type that is simpler with respect to furnaces of the state of the art and thus less costly with respect to the latter.
• Another object is to provide a furnace in which the billet can be heated at the desired temperature uniformly over the entire length.
• a further object is to provide a furnace of the aforementioned type in which there can be heated several unprocessed billets (billets not subjected to particular surface treatment) consecutively arranged along the axis of the furnace.
• figure 1 shows a perspective view of a first embodiment of the invention in a first operating position
• figure 2 shows a view similar to that of figure 1, but of the furnace according to the invention in a different operating position;
• figure 16 shows a lateral view of the application of figure 14 with the furnace according to the invention in exploded view
• the radial rotating magnetic field generated contrary to the longitudinal one that is usually generated in the prior art magnetic induction furnaces, enables having a more homogeneous and better heating of the billet with respect to what can be obtained with the prior art solutions; in particular, it enables obtaining a heating of the billet 2 such that the outer temperature (superficial) of the latter differs very slightly with respect to the internal temperature thereof (core) .
• the heating part 6 of the furnace 1 is preferably associated to a fixed structure 10 comprising a base 11, at least one screw 12 (or equivalent movement actuator with axis Z), of the recirculating ball or trapezia type, and a pressing element 13 arranged at a distance from such base 11.
• the terminal part 13A of the pressing element may move in a floating fashion with respect to the vertical axis W of such element 13 (i.e. oscillating around the axis W) so as to adapt to possible inclinations of the free terminal parts of the billet at contact therewith with respect to such axis .
• the part 6 has a heating part 6 mobile with respect to the base 11 along the guides 15 (vertical and lateral with respect to the part 6) which connect the base with a castle 16 arranged above the base; the part 6 is associated with a threaded element (spiral) 600 fitted on the screw 12 which in turn rotates in the castle 16 carrying the pressing element 13 through the action of a kinematic unit 18 made up of a motor, transmission or gear motor provided with a service brake on suitable gears (not shown) cooperating with the screw 12. In case of electrical power failure, the service brake is deactivated and the heating part 6 slides along the guides 15 by means of the screw 12 moved by the weight thereof, freeing the billet 2.
• a threaded element 600 fitted on the screw 12 which in turn rotates in the castle 16 carrying the pressing element 13 through the action of a kinematic unit 18 made up of a motor, transmission or gear motor provided with a service brake on suitable gears (not shown) cooperating with the screw 12.
• the service brake is deactivated and the heating part 6
• At least one from among said plate 21A and said element 13 comprises means for measuring the temperature of the billet (for example, means operating at contact such as a thermocouple or from a distance such as optical pyrometers) which enable detecting the temperature thereof in the heating step and controlling the magnetic induction heating of the billet.
• means for measuring the temperature of the billet for example, means operating at contact such as a thermocouple or from a distance such as optical pyrometers
• Such control is carried out by a special unit for commanding and controlling the various functions of the furnace, not represented.
• the control unit also cooperates with an element suitable to measure the pressure exerted by the pressing element 13 on the billet.
• Such measurement element is advantageously, for example, a load cell. Thanks to the pressure data detected by such cell and the temperature data detected by temperature measurement means, the control unit adjusts the pressure exerted by the pressing element 13 as a function of the energy used for heating generated by the heating part 6.
• the pressure measurement element is also used for safety purposes for controlling the pressure exerted on the billet with the aim of avoiding deformation thereof (for extending the same when hot) and possible problems to the furnace as a whole.
• various heating sections 25 are mutually axially superimposed (for example preferably being 2, 4, 6 or 8), each section having an annular motor 250 thereof; the entirety is arranged in a container 28 defined by the lower portion 20 and by the lateral plates 22 mentioned above, as well as by other plates 22A arranged on other sides of the part 6 different from those where the plates 26 are arranged.
• the container 28 is shaped to form a solid polygon (parallelepiped or cube, as a function of the number of sections 25 present) whose upper face 28A is open and delimited by the section placed at the top part of the stack of sections 25 present in the container .
• Such container is mobile, in its entirety, along the guides 15 towards the castle 16 and thus receives in the seat 27 a billet arranged on a plate 21A which remains fixed in that integrally joined to the column 21 in turn integrally joined to the base 11.
• Such movement is obtained by rotating the screw 12 by means of the kinematic unit 18, said movement leading to the sliding of the threaded element 600 therealong and thus the movement of the part 6 along the guides 15.
• Such movement i.e. the sliding of the part 6 with respect to the base 11, is controlled by a linear transducer arranged in the castle 16 (and not shown) .
• such linear transducer is associated to the pressing element 13 so as to enable measuring the exact length of the billets through an initial movement of such element 13 after loading the billet into the furnace 1 which brings such element 13 to contact with the billet. This exploiting the fact that the plate 21A is fixed and it determines the reference plane .
• a pick-up arm that moves it from the furnace to a forging machine may always be positioned and grasp it at the most appropriate point with the aim of avoiding unbalancing thereof during the displacement thereof or to allow it to overcome possible obstacles present along the displacement path.
• the billet 2 can access the seat 27 from the face 28A, said seat starting at such face and terminating at the portion 20 mentioned further above.
• annular rotor 40 (or calibrator magnetic body which also serves as a spacer, which is cylindrical in the embodiment of the figures) defined by at least one annular body 41 containing an annular cylindrical member 41A with an axial hole and carrying a plurality of fixed permanent magnets 43 whose arrangement defines seats 44 that can be conveniently used as channels for cooling the magnets and applied to the body 41 thereof.
• the body 40 (or "annular magnetic rotor" considering such body 40 as a whole i.e. with the body 41, the member 41A and the magnets 43) rests on bearing members 47 interposed between the permanent magnet rotor 34 and the hollow portions 48 provided inside the body 41 in proximity of the juxtaposed ends thereof.
• the member 41A may have different embodiments with different axial holes thus defining seats 27 of different shape for the different billets.
• rotor 40 may also be formed to shape a simple ring supporting the magnets 43 in suitable seats of the body thereof 41.
• Each section 25 comprises, as mentioned, the end covers for closing the bearings 49B and corresponding end magnetic flanges 49A suitable to close the magnetic field of the magnets (and maintain it in the group of the magnets 43) and a flange for supporting the bearings 49C.
• the rotors project from the containment body 30 and they are guided in rotation by a plurality of grooved discs 50 freely rotating on pins 51 fixed at angular portions 51A of such body. Every grooved disc 50 has a cavity 54 with which there cooperates a flange or collar 55 radially projecting from the corresponding rotor.
• the embodiment of the invention of figures 1-3 provides for that the heating part 6 be mobile along the guides 15 to carry out the heating of the billet.
• the heating part 6 rests on the base 11. Maintaining this configuration, a billet 2 is positioned (by a common handling device, not shown, outside the furnace 1) between the pressing element 13 and the plate 21A and the pressing element 13 is actuated to block such billet between it and the plate 21A.
• the part 6 is thus lifted by the rotation of the screw 12 towards the castle 16 until it covers the entire billet 2 i.e. until it is entirely into the seat 27.
• the entirety of the sections 25 stacked in the body 30 cover the entire length of the billet 2.
• thermocouples associated to the pressing element 13 and the plate 21A may be arranged between the various heating sections 25 so as to enable measuring temperature along the billet and not just on the two heads or ends only. This enables a better monitoring or control of the temperature trend i.e. the heating of the billet along the entire axis thereof.
• the motors 25 are deactivated and the part 6 is returned to the base 11; the billet thus heated (held by the element 13 on the plate 21A) is removed from the furnace 1 (for example by means of a handling device) and inserted, even directly, into an extruder through this or another handling device (not shown) .
• the furnace 1 for example by means of a handling device
• the furnace may have small transversal dimensions (slightly bigger than one or two metres per side on the plane P) and be arranged on the side of the extruder, thus enabling quick loading of the heated billet into the latter .
• the billet may simply be placed on the plate 21A associated to the heating part 6 of the furnace 1 (and which is the part actually serving as a "furnace" of the latter) and preferably pressed on the plate 21A by the pressing element 13.
• the motors 250 used are of then ring-like coaxial type, as mentioned, and preferably they are advantageously of the three-phase synchronised type provided with a number of poles and windings necessary for optimising torque and having the required power.
• Such motors have a high performance at around 95%. They are "sensorless” i.e. they are not provided with transducers for setting the position of the rotor and the motor revolutions. Thanks to a calculation algorithm, the aforementioned control unit of the furnace provides the synchronisation of all motors 250 of the part 6 and their correct variation of the number of revolutions as a function of the temperature distribution requirement desired in the billet and possibly the cone temperature.
• Each magnetic rotor 40 has a number of poles not bound to a specific value and this number can be an even or odd number and greater than two in any case.
• the magnetic induction furnace in question has a high performance at around 95%.
• the magnets used Neodymium Iron Boron, NdFeB
• NdFeB Neodymium Iron Boron
• the part 6 of the furnace 1 is fixed to the base 11 while beneath the latter there is provided for a well or compartment 60 (obtained in a plane P on which such base lies) in proximity of which there is present a mobile support 61 for the billet 2.
• a mobile support 61 for the billet 2 is associated to an actuator 62 (for example a screw 63 driven by an electric motor 64) contained in such compartment 60.
• the support 61 is arranged in proximity of the base 11 i.e. of the lower portion 20 of the furnace 6 which - contrary to the embodiment of figures 1-3 - is provided with a central hole 66 coaxial with the seat 27 for the billet.
• such support (called axis Z) is raised in the seat 27 up to the upper face 28A of the container 28 of the part 6, through the actuator 62; there is thus positioned, on such support 61, the billet 2 which is thus pressed against the support of the pressing element 13.
• both the pressing element 13 and the actuator 62 move jointly along the axes Z and W of the seat 27 inserting the billet into the heating part 6 and holding it fixed and blocked in such seat. After the heating thereof (obtained using the heating sections 25), such movement is reverse repeated and the heated billet is removed from the seat 27 so as to be removed from the furnace .
• FIGS. 10-13 show a further variant of the invention.
• parts corresponding to those of the figures described previously are indicated using the same reference numbers.
• the furnace 1 comprises a base 11 having end uprights 110 supporting pressing elements 13 (similar to that 13 of figure 1 already described) , driven by linear actuators of the hydraulic, pneumatic or hydro-pneumatic type.
• Each pressing element has an actuator 130 and the mobile plunger 13A (carrying a body 131 suitable to cooperate with the billet 2 at an end thereof) .
• the furnace comprises a base 11 having end uprights 110 supporting pressing elements 13 (similar to that 13 of figure 1 already described) , driven by linear actuators of the hydraulic, pneumatic or hydro-pneumatic type.
• Each pressing element has an actuator 130 and the mobile plunger 13A (carrying a body 131 suitable to cooperate with the billet 2 at an end thereof) .
• the furnace comprises a base 11 having end uprights 110 supporting pressing elements 13 (similar to that 13 of figure 1 already described) , driven by linear actuators of the hydraulic, pneumatic or hydro-pneumatic type.
• Each pressing element has an actuator 130 and the mobile plunger 13A (carrying a body 131 suitable to
• a handling device 300 for example a small overhead crane or carriage 310 moveable along overhead guides 311 and provided with its own means for actuating the movement; said handling device comprises mobile gripping members 313, for example a clamp, associated to a vertical movement member (for example a support arm or, a pulley, an overhead crane) 314 which enables taking a billet 2 (moved along the overhead guide 311 by the carriage 310) at the axis M when the juxtaposed pistons 13A are in a position such to space the bodies 131.
• a vertical movement member for example a support arm or, a pulley, an overhead crane
• one or more mobile saddles associated to the base 11 support the billet along such axis M.
• FIGS 14-16 show a particular application of the furnace 1 according to the invention to a common gas furnace 400.
• parts corresponding to those described previously are indicated using the same reference numbers.
• the fist (403) is interposed between the body 401 and the heating section 25 and the second (404) is arranged frontally i.e. on the vacant wall of the furnace 1. They respectively serve as a spacer and protection.
• the furnace 1 applied to the gas furnace 400 enables heating the end of the billet, already heated by the furnace 400 and exiting therefrom, at a temperature different from that of the gas furnace, thus enabling a cone-like heating of the billet (i.e. creating a cone temperature trend therein) .
• the billet exiting from the furnace is secured by the half-clamps 449 and 450 of the clamp means 445 of the bodies 401 and 402 and held stationary while the section 25 heats it according to the methods described regarding the previous figures.
• the furnace 1 may be moved (for example through driving means not shown) on one side of the exit opening of the billet of the furnace 400.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• General Induction Heating (AREA)
• Vertical, Hearth, Or Arc Furnaces (AREA)
• Furnace Details (AREA)
• Extrusion Of Metal (AREA)
• Furnace Charging Or Discharging (AREA)

Applications Claiming Priority (2)

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• 2015
  • 2015-11-11 IT ITUB2015A005468A patent/ITUB20155468A1/it unknown
• 2016
  • 2016-11-11 PL PL16812817.1T patent/PL3375252T3/pl unknown
  • 2016-11-11 ES ES16812817T patent/ES2928166T3/es active Active
  • 2016-11-11 JP JP2018521428A patent/JP6929839B2/ja active Active
  • 2016-11-11 WO PCT/IB2016/001622 patent/WO2017081532A1/en active Application Filing
  • 2016-11-11 EP EP16812817.1A patent/EP3375252B1/en active Active
• 2021
  • 2021-08-06 JP JP2021129525A patent/JP7176064B2/ja active Active

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