Metal deforming – By application of fluent medium – or energy field – By kinetic energy of fluid or field
Reexamination Certificate
2000-08-29
2003-05-20
Jones, David B. (Department: 3725)
Metal deforming
By application of fluent medium, or energy field
By kinetic energy of fluid or field
C072S707000, C072S055000, C029S419200
Reexamination Certificate
active
06564605
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
The present application is the national stage under 35 U.S.C. 371 of PCT/IL98/00629, filed Dec. 29, 1998.
FIELD OF THE INVENTION
The present invention is generally in the field of pulsed magnetic forming (PMF) and provides an apparatus and method for such forming. More particularly, the present invention relates to a PMF process forming of a dish from a planar plate.
BACKGROUND OF THE INVENTION
Metal objects can be formed to have a desired shape by a variety of processes. For example, metal in a liquid form, can be molded to have the desired final shape. However, such a process is applicable in certain specific cases and in addition requires the expense of a large amount of energy and complicated and costly installations for heating and cooling.
Metal has some pliability and accordingly metalwork pieces of one shape can at times be formed to have another shape. For example, a metal plate can be formed and cut to have a wide variety of desired shapes by using a mechanical press. Such pressing methods require a very costly and large installations required for achieving the necessary pressure for attaining the desired final object.
PMF is a process in which a metal workpiece or a portion thereof is put into a rapid motion by pulse magnetic fields which causes the workpiece to deform. One advantage of the PMF process is in that energy loss in this process is minimal and consequently there is no or very little heating of the workpiece. In addition, this process does not have the disadvantage of leaving tool marks, as is the case in a variety of other techniques. The PMF process uses a discharge capacitor or a bank of capacitors, a forming coil and often a field shaper, for creating an intense transient magnetic field. Very intense magnetic fields created in the PMF process, is a result of the rapid discharge of electric energy, stored in the capacitors, through the forming coil. The resulting eddy currents that are induced in the workpiece yields a magnetic repulsion between the workpiece and the forming coil, which cause the workpiece to deform.
A background on prior art apparatuses and methods for working of metal workpieces by the PMF process can be found in U.S. Pat. Nos. 3,654,787, 3,961,739, 4,170,887, 4,531,393, 4,807,731, 5,353,617 and 5,442,846, and in PCT Application Publication No. WO 97/22426.
When forming a shaped metal object from a planar metal plate, it is necessary at times to both shape a plate to acquire a desired three-dimensional pattern and to trim the edges so as to define the boundaries of the shaped metal object.
It is an object of the invention to provide PMF forming apparatus and method for forming a metal plate into a dish having a desired three-dimensional pattern and shape.
GENERAL DESCRIPTION OF THE INVENTION
The present invention provides, by a first of its aspects, an electromagnetic forming apparatus for forming an essentially planar metal plate into a dish having a three-dimensional pattern. A typical non limiting example of the invention is its application in the formation of a satellite dish from a planar plate.
In accordance with one embodiment, the apparatus comprises:
a mold having a forming surface with a contour corresponding to said three-dimensional pattern, and having edges corresponding to boundaries of the dish, which edges are defined by side walls essentially perpendicular to the forming surface;
a forming coil device opposite and proximal to said forming surface, and extending peripheral to said edges; the plate being
accommodated between the forming coil and said forming surface; and
an electric discharge circuitry for discharging a short and intense electric current pulse through the forming coil device to yield a pulsed magnetic forming (PMF) force for deforming said plate.
In accordance with one embodiment of the invention, the forming coil comprises a single coil member. In accordance with another embodiment of the invention, the forming coil device comprises an array of two or more coil members. The coil members in a forming coil comprising two or more coil members are typically concentric. An apparatus in accordance with this embodiment comprises:
a mold having a forming surface with a contour corresponding to said three-dimensional pattern;
a forming coil device opposite and proximal to said forming surface comprising two or more coil members; the plate being accommodated between the forming coil and said forming surface; and
an electric discharge circuitry, comprising two or more discharge circuitries, one associated with each coil member, for discharging short and intense electric current pulses through the coil members to yield pulsed magnetic forming (PMF) forces for deforming said plate.
In the case of a forming coil comprising two or more coil members, the discharge circuitries may be timed to discharge the current pulse through all coil members simultaneously; or advantageously, the discharge is timed in accordance with a predetermined discharge sequence. For example, in the case of several concentric coil members, the discharge sequence may be such so that it propagates from the central coils to the peripheral ones; in the reverse direction, namely from the peripheral ones towards the central ones; or in any other desired discharge sequence designed to obtain a certain three-dimensional pattern.
In accordance with another embodiment of the invention, the forming coil comprises one or more coil members which are displaceable along an axis essentially normal to a plane defined by the metal plate. The apparatus in accordance with this embodiment comprises:
a mold having a forming surface with a contour corresponding to said three-dimensional pattern;
a forming coil device comprising one or more coil members, displaceable along an axis essentially normal to a plane defined by the metal plate;
an electric discharge circuitry, comprising two or more discharge circuitries, one associated with each coil member, for discharging short and intense electric current pulses through the coil members to yield pulsed magnetic forming (PMF) forces for deforming said plate.
The forming coil in the apparatus according to this embodiment typically comprises two or more coil members separately displaceable along said axis. The deformation of the plate may comprise two or more steps. In the first step, the plate is partially deformed by a PMF force and then the coil members are displaced to an axial position corresponding to the displacement of the plate after the initial deformation. Then a PMF pulse is discharged again to further deform the plate, and this process may be repeated until the final shape has been attained.
In accordance with another embodiment of the invention, the forming coil device, which may comprise one or more coil members, has a size such that it covers only a portion of the plate to be deformed. An apparatus in accordance with this embodiment comprises:
a mold having a forming surface with a contour corresponding to said three-dimensional pattern;
a forming coil device opposite and proximal to said forming surface, and comprising one or more coil members having a size such that it covers only a portion of the plate to be deformed, the one or more coil members being displaceable in plane parallel to that of the plate;
an electric discharge circuitry for discharging a short and intense electric current pulse through each of the one or more coil members to yield a pulsed magnetic forming (PMF) force for deforming said plate.
In accordance with this embodiment, the forming coil member is first positioned at an initial position, a PMF pulse is generated to partially deform the opposite portion of the plate and then the forming coil is moved to another position opposite another portion of the plate whuch is then deformed by another PMF pulse. These steps are repeated untill the entire plate has been deformed to assume said there-dimensional pattern.
The mold, in accordance with one embodiment, comprises one or more depressions which correspond to said three-dimensional pattern. Typi
Gafri Oren
Livshiz Yuri
Browdy and Neimark , P.L.L.C.
Jones David B.
Pulsar Welding Ltd.
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