"HEATING DEVICE FOR METAL PRODUCTS"

FIELD OF THE INVENTION

The present invention concerns a heating device for metal products used for example in the industrial, manufacturing or mechanical field or in general to heat localized parts of a metal by means of electromagnetic induction.

In particular, the present invention can be used for example to weld/unweld, straighten and/or deform, heat and/or quench one or more metal products.

BACKGROUND OF THE INVENTION

Among the various types of heating devices using electromagnetic induction for metal products, various heating devices are known.

Thanks to their functional and structural characteristics, such electromagnetic induction heating devices are normally preferred rather than resistive heating devices or those using flames.

Here and hereafter in the description we will refer to electromagnetic induction heating devices, and therefore, except where otherwise indicated, it is understood that by heating device we mean an electromagnetic induction heating device.

Known induction heating devices are normally provided with an electric power unit which is configured to generate an alternating electric current at a frequency comprised between 10 kHz and 1000 kHz and more.

The alternating electric current is used to generate an alternating magnetic field in the heating tool or tip of the device, which induces parasite currents in the metal product located nearby or in contact.

The parasite currents cause a rise in temperature of the metal product due to the Joule effect, functionally dependent on the power actually transmitted from the power unit to the heating tool.

One of the main problems of known induction heating devices is that they have high electromagnetic losses which do not allow them to reach high values of the power transmitted.

Among known solutions there exists an induction heating device for supplying the necessary energy in the designated place which provides a first tubular component and a second tubular component, coaxial with each other and connected by a connection member. The tubular components are also intended to cool the heating tool.

The connection member connects the heating tool to the power unit and transmits the alternating electric current from one tubular component to the other. In this known solution, one end of the heating tool is connected to a tubular component with a mechanical connection member, while the other end is connected to the other tubular component by coupling through interference, typically guaranteed by a packing.

The known connection member, because of how it is structured, does not guarantee a certain contact between the external tubular component and the heating tool, so that it is not possible to transmit high alternating electric currents to the heating tool.

This limits the possibilities of using such heating devices only for limited powers transmitted, typically comprised from 3kW to 4kW.

Because of the packing and possible air gaps present in the state of the art, between the connection member and the external tubular component, there are considerable electromagnetic losses both due to an increase in the resistance and also due to an interruption in the flow lines of the magnetic field.

Another disadvantage of this known solution is that, because of the operations to reactivate the heating tool, the contact between the connection member and the external tubular component becomes less and less effective, until it even deforms or damages the latter. Every structural deformation of the external tubular component and/or the connection element represents a further source of electromagnetic losses, which are added to those already present, further limiting the power actually transmitted.

A heating device is also known from US-A-3.022.368, and comprises an electric power unit to which a flexible, coaxial cable unit is connected, at the end of which a heating tool is connected.

The coaxial cable unit comprises an external flexible tube and an internal flexible tube positioned inside the external flexible tube and defining a hollow space for the passage of the cooling liquid.

The internal flexible tube and the external flexible tube have respective ends, each connected to respective terminal boxes connecting to the electric power unit.

The other ends of the internal flexible tube and the external flexible tube are connected to the heating tool by a plurality of connection elements. This makes it extremely complex and difficult to replace the heating tool.

Furthermore, the internal flexible tube and the external flexible tube are very long, to allow an operator to reach the piece to be worked with the heating tool.

Given the particular conformation of the electric power unit, high currents are supplied to the internal flexible tube and the external flexible tube for the whole of their extension.

However, the great length of the flexible tubes causes high electromagnetic losses and therefore a reduction in the heating efficiency of the heating tool.

There is therefore a need to perfect the state of the art and to make available a heating device for metal products that overcomes at least one of the disadvantages of the state of the art.

One purpose of the present invention is to obtain an induction heating device for metal products that does not have high electromagnetic losses and that allows to have higher powers transmitted than in the state of the art.

Another purpose of the present invention is to supply a heating device for metal products that guarantees a stable connection, without electromagnetic losses between the components.

The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.

SUMMARY OF THE INVENTION

The present invention is set forth and characterized in the independent claim, while the dependent claims describe other characteristics of the invention or variants to the main inventive idea.

In accordance with the above purposes, the present invention concerns an electromagnetic induction heating device for metal products comprising:

- a support body defining a containing chamber of an electric power unit configured to power and transmit alternating electric current;

- a first tubular component positioned partly inside the support body and which protrudes from the latter through a through cavity; - a second tubular component associated with its first end to the support body and in which the first tubular component is inserted, so as to define a hollow space between them;

- a connection member provided with a heating tool configured to connect the first tubular component and the second tubular component with each other, said heating tool having a pipe in its thickness to connect fluidically the first tubular component with the hollow space.

According to one aspect of the present invention, the heating device also comprises:

- first removable mechanical connection members, located in the connection member and connecting the first tubular component and the connection member, and

- second removable mechanical connection members configured to connect the external second tubular component to the support body or to the connection member.

According to possible embodiments, the first tubular component and the second tubular component are defined by rigid metal tubes.

This allows to obtain a device resistant to knocks and crushing.

According to possible embodiments, the first tubular component and the second tubular component are coaxial with respect to each other.

This allows to obtain high performances of electric energy transfer, considerably reducing electromagnetic losses.

According to advantageous solutions, the first mechanical connection members and the second mechanical connection members are installed coaxially to the first tubular component and to the second tubular component.

This configuration considerably simplifies the assembly and/or replacement operations of the heating tool, since it is possible to act exclusively from the outside along a single axis of rotation.

According to one aspect of the present invention, the connection member comprises a connection bushing configured to connect the heating tool with the first tubular component, said connection bushing being hollow inside and fluidically connecting the pipe of the heating tool with the internal cavity of the first tubular component. According to one aspect of the present invention, the first connection members comprise a threaded hole made in the first connection bushing and a threaded end made in the first tubular component screwed to the threaded hole.

In this way the first and the second mechanical connection members define an electric continuity, which eliminates or reduces the electromagnetic losses compared to the state of the art.

The alternating electric current, as a function of the oscillation frequency and the power actually transmitted, generates an alternating magnetic field on the heating tool generating the parasite currents, which turns out to be considerably more intense than the fields generated with known induction heating devices.

Thanks to this, the device according to the present invention allows to reach powers transmitted even higher than 20 kW.

Moreover, the present invention has a sure connection between the second tubular component and the connection member, which makes continuous operations to control and reposition its parts no longer necessary, thus avoiding wear and/or deformations and/or losses of power.

By means of the second mechanical connection members losses of power are prevented and therefore the performance of the whole device is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other characteristics of the present invention will become apparent from the following description of some embodiments, given as a non-restrictive example with reference to the attached drawings wherein:

- fig. 1 is a section view of an embodiment of a heating device for metal products according to the present invention;

- fig. 2 shows a detail of fig. 1 ;

- fig. 3 is a section view of a possible variant of fig. 1.

To facilitate comprehension, the same reference numbers have been used, where possible, to identify identical common elements in the drawings. It is understood that elements and characteristics of one embodiment can conveniently be incorporated into other embodiments without further clarifications.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

With reference to the drawings, which show non-restrictive examples of the invention, we will now describe embodiments of a heating device 10 for metal products.

By metal products, we mean, by way of example, elements of any shape and section made with one or more metals or their alloys or also an element comprising a conductor material which is able to admit electric currents.

According to one aspect of the present invention, the electromagnetic induction heating device 10 comprises at least:

- a support body 1 1 ;

- a first internal tubular component 12;

- a second external tubular component 13 in which the first tubular component 12 is inserted, so as to define a hollow space 14 between them;

- a connection member 15 provided with a heating tool 16 configured to connect the first tubular component 12 and the second tubular component 13 with each other, and possibly to connect the first tubular component 12 fluidically with the hollow space 14 that is formed between the two tubular components 12 and 13; - an electric power unit 17 associated with the support body 11 and configured to power and transmit alternating electric current to the heating tool 16;

- first removable mechanical connection members 18, located in the connection member 15 and which connect the first tubular component 12 and the connection member 15.

According to one embodiment, the support body 1 1 defines, for example by means of a metal casing 11 1, possibly coated with an insulating material, a chamber 1 la containing the power unit 17.

According to one embodiment, the power unit 17 can be contained in the chamber 1 la.

In particular, the casing 111 can be made of copper or other metal material suitable to transmit alternating electric current with negligible losses of power.

The electric power unit 17 located inside the support body 11 allows to generate the high heating currents that have to be supplied to the heating tool 16. According to possible embodiments, the two tubular components 12 and 13 are made of a conductive metal material, for example copper or other metal material suitable to transmit alternating electric current with negligible losses of power.

According to some solutions, the first tubular component 12 and the second tubular component 13 are defined by rigid metal tubes. The presence of rigid metal tubes allows to transfer efficiently high electric powers, reducing losses thereof.

Furthermore, the fact that the first tubular component 12 is positioned partly inside the support body 11, and the fact that the second tubular component 13 is connected to the latter, allows to transfer directly the high currents to the heating tool 16, through the first and second tubular components 12 and 13.

For example, they can be made of a copper alloy which at the operating frequencies of the heating device 10 allows electromagnetic losses of less than 5% of the power supplied.

According to one embodiment, not shown, the electric power unit 17 can comprise a generator of alternating electric current, typically with values comprised between 100 A (Amps) and 2000A, or can comprise a transformer configured to obtain alternating current with values comprised in the same range. According to a possible embodiment, the transformer can comprise a primary circuit 26 and a secondary circuit 27, configured to obtain in the secondary circuit 27 alternating electric current with values comprised between 100A and 2000A at a frequency comprised between 10 kHz and 1000 kHz. The oscillation frequency of the alternating electric current can also be higher than 1000 kHz.

The primary circuit 26 can comprise an electric cable 28 wound around a hollow ferromagnetic core 29 and which can be made with one or more ferromagnetic elements 30. For example, the ferromagnetic core 29 can be made of iron oxides and/or other ferromagnetic materials.

According to one embodiment, the casing 11 1 can comprise a first aperture 31 through which the two ends of the electric cable 28 are disposed through.

Advantageously, from the same aperture 31 a cooling fluid can be introduced into/removed from the chamber 1 1a and, for this purpose, the first aperture 31 can be connected to a fluid feed pipe 42.

As will become clear hereafter in the description, after having been introduced into the chamber 11a, the cooling fluid flows through the hollow space 14, the heating tool 16, the channel defined by the first tubular component 12 and exits through a connection pipe 32 disposed, in this case, passing through a second aperture 33 made in the casing 1 1 1. According to variant embodiments, the cooling fluid is made to circulate in the opposite direction.

According to one embodiment, the heating device 10 is also configured to allow the cooling fluid to flow in the opposite direction.

According to a possible embodiment, inside the cavity defined by the hollow ferromagnetic core 29 the first tubular component 12 is disposed through.

According to one embodiment, following the passage of alternating electric current in the electric cable 28 of the primary circuit 26, and as a function of the structural characteristics and the electric parameters of the primary circuit 26, the ferromagnetic core 29 induces in the secondary circuit 27, on each occasion, a desired alternating electric current based on the metal product to be heated.

According to one embodiment, the secondary circuit 27 of the transformer is defined by the closed-ring spiral that comprises the first tubular component 12 and the second tubular component 13, connected to each other at the ends, on one side by the support body 11 and on the other side by the connection member 15.

According to one embodiment, the first tubular component 12 can be coated along part of its longitudinal extension by an insulating sheath, for example thermo-shrinkable, or other similar element.

This feature is advantageous to prevent a possible short-circuit which could occur between the first and second tubular components 12 and 13 through the hollow space 14.

According to one embodiment, the support body 11 is solidly connected to the first internal tubular component 12, for example by welding the first tubular component 12 on the casing 111 of the support body 11.

In the solution shown in fig. 1, the casing 1 11 and the first tubular component 12 are connected solidly by means of the connection pipe 32.

In these two embodiments, the first internal tubular component 12 is electrically and mechanically connected to the casing 111 of the support body 11. According to the solution shown in figs. 1 and 3, the casing 111 is provided with a through cavity 43 through which the first tubular component 12 is positioned through.

In particular, the first tubular component 12 is solidly attached on the bottom of the casing 1 11, and protrudes from the chamber 1 la through the through cavity 43 without reciprocal contact between the parts.

A first end of the first tubular component 12 is therefore attached to the support body 1 1 and a second end, opposite the first end, is connected to the connection member 15 with the first mechanical connection members 18.

According to one aspect of the present invention, the heating device 10 also comprises second removable mechanical connection members 25, configured to connect the second external tubular component 13 with the connection member 15 or the support body 1 1.

Thanks to this feature, the electric connection between the connection member 15 and the second tubular component 13 is considerably improved, which leads to a considerable reduction in the electromagnetic losses of the heating device 10.

According to possible embodiments, the first mechanical connection members 18 and the second removable mechanical connection members 25 are separate and distinct from each other.

This solution simplifies the assembly operations and considerably reduces electromagnetic losses.

According to a variant embodiment (fig. 1), the second external tubular component 13 is connected with a first end to the casing 111 of the support body 11, by means of the second removable mechanical connection members 25 and, with a second end, is solidly connected to the connection member 15.

According to one embodiment (fig. 1), the second mechanical connection members 25 can comprise a first ring nut 34 and a first threaded portion 35, associated respectively with the second tubular component 13 and the casing 1 1 1 of the support body 11.

According to another embodiment, the first ring nut 34 and the first threaded portion can be associated respectively with the casing 1 11 and the second tubular component 13.

The first threaded portion 35 can be made in correspondence with the through cavity 43 made in the casing 111.

The first ring nut 34 is screwed onto the protruding threaded portion 35 of the casing 1 11 until it abuts against a first reference element 36 provided on the external wall of the second tubular component 13, or on the casing 11 1.

The first reference element 36 functions as a reference for screwing the first ring nut 34 and can be an abutment ring, an element provided with a nose or can also consist of several radially protruding elements.

This type of connection guarantees a certain connection between the support body 1 1, or the casing 111, and the second tubular component 13, so as to obtain an electromagnetic continuity with minimum electromagnetic losses.

In fact, the thread of the first ring nut 34 mating with the first threaded portion 35 ensures that there is an electric contact between the support body 1 1 and the second external tubular component 13 over a wide surface.

According to the embodiments in figs. 1-2, the connection member 15 comprises a terminal body 40 provided with a through seating 41 in which the first and second tubular components 12 and 13 can be at least partly inserted.

In particular, the second end of the second tubular component 13 is solidly attached, for example by welding, to the terminal body 40.

According to a possible embodiment, the heating tool 16 comprises a shaped metal pipe 19, which can be conformed so as to define a portion with the shape of a toroidal arc where, during use, the magnetic field is generated that is able to induce parasite currents in the metal product.

The heating tool 16 is connected fluidically to the through seating 41 of the terminal body 40 with a first end.

The heating tool 16 is in turn fluidically connected, with a second end, to the first internal tubular component 12.

According to the solution shown in fig. 2, the terminal body 40 is provided in its thickness with a connection channel 21 in correspondence with which it connects the heating tool 16.

The connection channel 21 is put in fluidic communication with the through seating 41 through an aperture 22 made in the thickness of the terminal body 40.

The connection channel 21 develops in this case substantially parallel to the axial development of the through seating 41.

The heating tool 16 is provided in its thickness with a pipe 19 through which, during use, the cooling fluid is made to transit.

In particular, the cooling fluid arriving from the second tubular component 13, that is, from the hollow space 14, is introduced into the through seating 41 of the terminal body 40, is made to pass through the aperture 22, transits in the connection channel 21 and, passing through the pipe 19 of the heating tool 16 is supplied to the first tubular component 12.

The heating tool 16 and/or the pipe 19 provided therein can be suitably shaped as a function of the specific requirements of the application.

In particular, the heating tool 16 can be shaped curved, to define a zone where, in use, it is put into contact with or near to the element to be heated. In fact, a magnetic field is generated on the heating tool 16 such as to induce parasite currents on the element to be heated.

According to a possible solution, the connection member 15 comprises a connection bushing 20 configured to connect the heating tool 16 with the first tubular component 12.

The connection bushing 20 is hollow inside and fluidically connects the pipe 19 of the heating tool 16 with the internal cavity of the first tubular component 12.

According to a possible solution, the connection bushing 20 is provided with a first end to which the heating tool 16 is connected, and a second end to which the first tubular component 12 is connected, with the first connection elements 18.

According to one solution, the connection bushing 20 is installed at least partly, for example coaxial, in the through seating 41 of the terminal body 40. According to another solution, between the terminal body 40 and the connection bushing 20 an electric insulating element 23 is interposed, configured to prevent a direct short circuit between the first tubular component 12 and the terminal body 40, bypassing the heating tool 16.

The insulating element 23 can be made of rubber or other similar material, and is also configured to ensure an effective hydraulic seal of the cooling fluid, so that it does not leak and is obliged to pass through the pipe 19 of the heating tool 16.

The connection bushing 20 is made of conductive material.

To obtain a better hydraulic and mechanical seal, a packing 24 can also be provided, which cooperates with the insulating element 23 and the terminal body

40.

The first connection members 18 are therefore provided between one end of the first tubular component 12 and the connection bushing 20. According to the solution shown in fig. 2, the first connection members 18 can comprise a threaded hole 20a made in the connection bushing 20 and a threaded end 12a made in the first tubular component 12.

The threaded end 12a is screwed to the threaded hole 20a so as to guarantee the mechanic and electric connection between the first tubular component 12 and the connection bushing 20.

According to another variant embodiment (fig. 3), the second mechanical connection members 25 connect a first end of the external second tubular component 13 with the connection member 15, or the terminal body 40, and the support body 11 is solidly connected with the second end of the second tubular component 13.

According to this variant, the casing 111 of the support body 1 1 can be welded to the second tubular component 13, or can be made in a single piece with it.

The end of the second tubular component 13 can be housed in a seating 37 made in at least part of the through seating 41 of the terminal body 40, so as to provide a reference position for the attachment of the second tubular component 13 to the connection member 15, by means of the second mechanical connection members 25.

According to one embodiment, the second mechanical connection members 25 can comprise a second ring nut 38 and a second threaded portion 44, associated respectively with the second tubular component 13 and the terminal body 40.

According to possible embodiments, when present, the first ring nut 34, the second ring nut 38, the second threaded portion 44 and the terminal body 40 are made of conductive material.

According to another embodiment, the second ring nut 38 and the second threaded portion 44 can be associated respectively with the terminal body 40 and the second tubular component 13.

The second ring nut 38 is configured to be screwed onto the second threaded portion 44 until it abuts against a second reference element 39 provided on the second tubular component 13 or on the terminal body 40 of the connection member 15.

According to one embodiment, the second reference element 39 can be conformed like the first reference element 36, it can be a nut screwable on the second threaded portion 44, it can comprise protrusions made on the external wall of the terminal body 40, or elements attached to it and configured to define an abutment position for the second mechanical connection members 25.

The variants described here optimize and perfect the electric connection between the connection member 15 and the second tubular component 13, so as to obtain a certain connection between them and to have limited electromagnetic losses.

The mechanical connection members 18 and 25 have been optimized to reduce to a minimum the electromagnetic losses, increasing the connection surface between the second tubular component 13 and the support body 11 and/or the connection member 15, preventing air gaps and/or other elements between them.

Thanks to the present invention, it is possible to obtain transmitted powers of more than 20 kW, which extend the possible fields of use of the heating device 10 to applications where high transmitted powers are required.

Furthermore, again thanks to the second mechanical connection members 25, it is possible to conform and if necessary modify the extension of the first and second tubular components so as to be able to reach zones to be heated that are typically not easily accessible with other devices.

For example, according to a possible embodiment, not shown, the heating device 10 can comprise an extension screwable on the two tubular components 12 and 13 by means of third mechanical connection members.

The third mechanical connection members are configured to connect the extension in the same way as the second mechanical connection members 25, that is, without significant electromagnetic losses.

The electromagnetic losses are also further reduced thanks to the coaxial configuration of the tubular components 12 and 13 which lower the overall resistance and allow to obtain very intense magnetic fields on the heating tool 16.

It is clear that modifications and/or additions of parts may be made to the induction heating device as described heretofore, without departing from the field and scope of the present invention.

Indeed it is quite obvious that at least the support body 1 1, the first tubular component 12, the connection member 15, or the terminal body 40 and the heating tool 16, and the second external tubular component 13 are made with one or more electrically conductive materials, so as to allow the alternating electric currents needed for the subsequent heating to be established along them.

It is also clear that, although the present invention has been described with reference to some specific examples, a person of skill in the art shall certainly be able to achieve many other equivalent forms of heating device, having the characteristics as set forth in the claims and hence all coming within the field of protection defined thereby.