Electric heating – Inductive heating – With workpiece support
Patent
1992-09-18
1994-12-13
Leung, Philip H.
Electric heating
Inductive heating
With workpiece support
219635, 219642, 219658, 219670, H05B 610
Patent
active
053731441
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a device for heating objects, consisting at least partly of metal. The device comprises a core, and at least one coil connectable to a source of current to induce a magnetic flux in the core. The device has utility, for example in the rubber industry, for preheating molds, where it is capable of considerably reducing the time required for preheating. It is useful in preheating metal parts included in other objects, and can be used for derubberizing, i.e. separating rubber from metal, in objects consisting of both rubber and metal. The device is also useful in shrink fitting metal objects.
In heating devices of this kind, there is a need for simplification, for reduction of leakage of magnetic flux, for ensuring against unintended induced currents, for reduction of heat loss, and for relieving the magnetic core from the load of heavy objects to be heated.
In previously known induction heating devices, the objects to be heated were supported by the poles of the magnetic core. That is, the object to be heated was placed between the poles of the core, and, simultaneously, a coil was arranged around the end portions of the poles of the core. One problem with this arrangement was that the core had to support the load imposed by the object to be heated. Another problem was that it was difficult to place the object in the device, because the coil impeded access to the space between the poles of the core. Still another problem was that the prior induction heating devices were incapable of handling large and/or heavy objects satisfactorily. Still another problem was that known devices were subject to heat loss and leakage flux.
SUMMARY OF THE INVENTION
The general object of this invention is to provide an induction heating device having all of the essential capabilities, but which eliminates the inconveniences encountered in the prior art. A particular object of the invention is to provide for the heating of heavy and voluminous objects by eliminating the loading of the core by the objects to be heated. Another object is to reduce heating losses by effecting improved contact between different parts of the core. Still another object is to make it easier to place objects to be heated or treated in position in the heating device. The foregoing objects are addressed by providing a table having a disc-shaped element of electrical insulating material, and by providing a core having a displaceable part.
In one embodiment of the invention, the table is disposed around a portion of the core. The table may be disposed around one of the poles of the core, e.g. the stationary pole, and has an opening through which the core extends.
In another embodiment, the table or disc-shaped element is arranged on a supporting frame consisting partly of metal, the metal part having a gap bridged by insulating material.
In another embodiment, the device comprises a press device arranged to press the displaceable part of the core against the stationary part of the core after the displaceable part has been moved to its intended operating position but before electrical current is supplied to the coil.
In a further embodiment, hoisting and supporting means are arranged around the core. The hoisting and supporting means may be arranged around one of the poles, e.g. the stationary pole, for elevation of the object to be heated from a table or conveyor which is adjacent to the poles of the core .
BRIEF DESCRIPTION OF THE DRAWING
Further characteristics and advantages of the invention will be apparent from the detailed description with reference to the drawings, in which:
FIG. 1 is a schematic side elevational view of a device in accordance with one embodiment of the invention;
FIG. 2 is a top plan view showing a supporting frame in accordance with another embodiment of the invention;
FIG. 3 is a schematic side elevational view of a device in accordance with still another embodiment of the invention; and
FIG. 4 is a side elevational view of a table in accordance with still another embodiment of the invention.
DESCRI
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