US3429359A - Method and apparatus for blowing cores using microwave energy - Google Patents

Method and apparatus for blowing cores using microwave energy Download PDF

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Publication number
US3429359A
US3429359A US457747A US45774765A US3429359A US 3429359 A US3429359 A US 3429359A US 457747 A US457747 A US 457747A US 45774765 A US45774765 A US 45774765A US 3429359 A US3429359 A US 3429359A
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United States
Prior art keywords
core
core box
microwave energy
sand
blowing
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Expired - Lifetime
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US457747A
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English (en)
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Ashley James Hollingsworth
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Northrop Grumman Guidance and Electronics Co Inc
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Litton Precision Products Inc
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Priority to US457747A priority Critical patent/US3429359A/en
Priority to FR60408A priority patent/FR1478864A/fr
Priority to BE680552D priority patent/BE680552A/xx
Priority to DE19661508676 priority patent/DE1508676B1/de
Priority to GB21973/66A priority patent/GB1132373A/en
Priority to NL6606859A priority patent/NL6606859A/xx
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Publication of US3429359A publication Critical patent/US3429359A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C7/00—Patterns; Manufacture thereof so far as not provided for in other classes
    • B22C7/06—Core boxes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C23/00—Tools; Devices not mentioned before for moulding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/12—Treating moulds or cores, e.g. drying, hardening
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C9/00—Reinforcements or ply arrangement of pneumatic tyres
    • B60C9/0042—Reinforcements made of synthetic materials

Definitions

  • This invention relates to core blowing devices and processes and more particularly to such devices and processes in which the core is cured'by the application of high frequency electromagnetic wave energy.
  • the most widely used material for constructing molds and cores in the foundry industry is sand to which has been added a suitable binder material to cause the mold or core to retain its shape until the metal has been poured and solidified.
  • a suitable binder material to cause the mold or core to retain its shape until the metal has been poured and solidified.
  • the core and mold are formed by a suitable process, several of which will be later described, the core is placed within the mold and molten metal is poured into the mold.
  • the outer mold is broken off and the metal object is usually vibrated to break up the sand in the core and the sand is poured out of the openings of the hollow cast device. The sand from the mold and core can then be recovered and used over and over.
  • the sand mold is traditionally made from so-called green sand, which is merely damp sand, packed around a model or pattern of the object to be cast.
  • This mold is usually made in two halves, each half being pressed around opposite halves of the model, thereby forming a two-piece hollow mold the inner surfaces of which reproduce the outer surface of the object to be cast.
  • the core must be of sturdier construction than the mold since the core, after being formed, must be placed within the two halves of the mold prior to the insertion of the molten metal. Since the core must be so handled, it would probably be broken if it were made of simple damp sand in the manner described above.
  • a later improvement on this method of making cores was the introduction of the so-called core blower.
  • This is a rather complex machine which utilizes core boxes such as was described above.
  • the core blower supports the core box in a suitable manner and blows the mixture of said and oil into the core box through a suitable opening therein.
  • the blowing opeartion both filled the box and compacted the sand mixture in the core box.
  • the filled core box is then removed from the core blower and placed in a furnace for baking as before.
  • thermosetting resin in place of the oil as a binder.
  • the resin is mixed with the sand and the mixture is blown into the core box by the core blower, as before.
  • the core box is kept hot in a conventional manner, either by electric heating elements or by gas burners, and heat is transferred by conduction from the core box to the resin, setting the resin and curing the core.
  • a core blowing device which includes a microwave cavity.
  • a core box is provided which is constructed from a cheap easily worked material which is transparent to microwave energy.
  • the core blowing device also includes a hopper or other suitable container which contains a mixture of sand and thermosetting resin as a binder. Suitable metering means measure a quantity of the mixture of said and resin into a blower chamber from which the mixutre is blown into the core box by compressed air. Microwave energy is then applied to the cavity to cause the resin to set, thereby curing the core.
  • the cavity is then opened, the core box separated and the core removed from the core box, after which the operation can then be repeated until the desired number of cores is formed.
  • FIGURE 1 shows a front view of a microwave core blower embodying the present invention
  • FIGURE 2 shows a side view of the device of FIG- URE l
  • FIGURE 3 shows a cross sectional view of the blower chamber and upper platen of the device of FIGURES 1 and 2;
  • FIGURE 4 shows a cross sectional view of the curing chamber of the device of FIGURES 1 and 2, with a core box in position;
  • FIGURE 5 shows a cross sectional view of the curing chamber of the device of FIGURES 1 and 2 which incorporates a second embodiment of the present invention.
  • FIGURES 1 and 2 therein are shown front and side views respectively of a microwave core blower device embodying the present invention.
  • the device includes a frame which supports most of the components of the core blower and a hopper 12 into which is placed a mixture of sand and a thermosetting resin, which mixture may be the same as is used in conventional core blowing machines such as was described above.
  • the hopper 12 is supported from frame 10 on rubber pads 14 and is connected at its bottom to the rest of the device through a large diameter rubber hose 16. This arrangement allows the hopper 12 to be vibrated, if desired, to keep the sand and resin mixture free flowing until the mixture is fed into the device. Since the hopper 12 is rubber mounted at all points of contact with the rest of the device, the vibration does not substantially affect any other components of the device.
  • Beneath rubber hose 16 is the blower chamber 18, with these sections being separated by a valve plate 20 such as will be described in greater detail later.
  • the bottom section 22 of blower chamber 18 has a trapezoidal cross section, as shown in FIGURES 1 and 2, and is closed on its bottom side by a plate 24.
  • the curing chamber 26 is formed of two halves or platens, an upper platen 28 and a lower platen 30.
  • the upper platen 28 is supported from cross arms 32 of frame 10.
  • Plate 24 is supported on the top of platen 28 and thus the cross arms 32 also support the weight of blower chamber 18.
  • matching holes are drilled in plate 24 and the horizontal surfaces of platen 28 and metallic tubes are provided to form a passageway for the mixture of sand and resin to travel from blower chamber 18 to the inside of a core box when the device is being used.
  • lower platen 30 The weight of lower platen 30 is supported on shaft 34 which is in turn connected to the piston of a hydraulic cylinder 36.
  • Cylinder 36 is supported from a mounting plate 38 which is in turn supported from cross arms 40 of frame 10.
  • Lower plate 38 is also positioned by guide shafts 42 which are secured between cross arms 32 and 44 of frame 10.
  • Microwave energy is supplied to curing chamber 26 through a wave guide 46 which connects the device to a console 48 which includes a microwave transmitter, and which may also include the control elements for the hydraulic and pneumatic portions of the device which are to be later described in more detail.
  • the microwave transmitter might include a magnetron which operates at a frequency of 2450 megacycles per second and a suitable power supply for the magnetron.
  • Such microwave transmitters are well known to those skilled in the art and are available from a number of commercial sources, such as Litton Industries, Atherton Division, 974 Commercial St., Palo Alto, Calif. Accordingly, details of the microwave transmitter will not be given herein.
  • FIGURE 3 shows a cross sectional view of the blower chamber 18 and the upper half platen 2'8 and shows details of how the sand and resin mixture is blown from the blower chamber 28 into the curing chamber 26.
  • plate 24 and the top wall of upper platen 28 have a plurality of aligned holes through which are fitted conductive tubes 50. These tubes serve as conduits for the sand and resin mixture when the mixture is blown into the core box, as will be seen in more detail in connection with the description of FIGURES 4 and 5 below.
  • FIGURE 3 also shows how wave guide 46 is connected through an opening 52 in upper platen 28 so that microwave energy may be coupled from wave guide 46 into curing chamber 26 when the microwave transmitter in console 48 is energized.
  • microwave energy may be coupled from wave guide 46 into curing chamber 26 when the microwave transmitter in console 48 is energized.
  • any other form of coupling of microwave energy from wave guide 46 into curing chamber 26 may also be used with the invention.
  • FIGURE 4 shows a view, partially in cross section, of the upper and lower platens 28 and 30 and lower chamber 18 and also shows a core box 54 positioned in the curing chamber 26.
  • Core box 54 is formed from any suitable material which is essentially transparent or lossless to microwave energy.
  • the outer dimensions of core box 54 are such that it completely fills the curing chamber 26 and is hollowed such that the surfaces of its inner chamber 56 reproduce the surface of the core it is desired to produce. It is not necessary to the present invention that the core box completely fill the curing cavity. It is sufficient that the core box be supported in the cavity sufficiently to withstand the internal pressure of the blowing operation, to be later described in detail.
  • the core box could be constructed of mating sections which do not completely fill the curing cavity but which are supported from the top and bottom walls of the cavity and which, because of mating portions such as alignment pins, remain firmly together during the blowing operation.
  • Core box 54 is made in two halves, with the upper half having openings through which conductive tubes 50 extend into the chamber 56.
  • the upper half of core box 54 is positioned in the upper platen 28 and the lower half of core box 54 in lower platen 30. If it is desired to reproduce a large number of identical cores, the two halves of core box 54 may be temporarily secured to their respective platens by any known expedient such as by being bolted to the platen.
  • Core box 54 may be formed from lossless materials such as plaster, polypropylene, silicone rubber or the like. Each half may conveniently be formed by making a model of the respective half of the core to be blown from a material such as wood and by casting the plaster, polypropylene, or silicone rubber around the wood model. Suitable holes for conductive tubes 50 may have been cast into the core box originally or may be drilled into the upper half thereof after the core box is formed.
  • cores corresponding to chamber 56 are produced in the following manner: As will later be described in more detail, a mixture of sand and resin is blown by compressed air through the tubes 50 into chamber 56, such that the chamber 56 is completely filled with the mixture of sand and resin and the mixture is suitably compacted. Microwave energy is applied through the coupling opening 52 to the curing chamber 26. Since the material from which core box 54 is constructed istransparent to microwave energy, all of the microwave energy is converted into heat in the sand and resin mixture. Since sand is also essentially lossless, this conversion may be effected in either of two ways.
  • a resin such as a urea resin or furan resin which is lossy may be selected and the microwave energy is converted into heat in the resin itself.
  • a relatively lossless resin such as a phenolic resin
  • a small amount of moisture may be included in the sand and resin mixture and the microwave energy is converted into heat in the moisture. This heat then triggers the .thermosetting reaction of the curing resin.
  • the tubes 50 are made from a conductive material, such as copper or any other suitable metal, and have an interior diameter less than one-quarter wave length of the frequency of microwave energy being used in the microwave core blower.
  • the conductive walls of the tubing shield the sand and resin mixture in the tubing from the microwave energy and the small diameter prevents any microwave energy from entering the lower ends of the tube. This prevents the sand and resin mixture from being cured in the tubes and clogging the tubes.
  • FIGURE 5 shows a cross sectional view of the curing chamber similar to that shown in FIGURE 4 but illustrates another embodiment of the present invention.
  • the two halves 58 and 60 of the core box are formed from a lossless flexible material such as silicone rubber and, as shown, the two halves of the core box are hollow or ballon-like having inflatable compartments in their walls.
  • Piping 62 is provided to communicate with the interior of the two halves of the core box 58 and 60.
  • the walls of the core box 58 and 60 may be reinforced with a material such as fiberglass to prevent the walls from stretching, and a lossless fluid is introduced under pressure through piping 62 into the interior of the core box halves 58 and 60.
  • This fluid under pressure causes the halves 58 and 60 to become rigid and to retain their shape when the sand and resin mixture is blown under pressure into the inner chamber 56.
  • the fluid may be either a liquid or air under sufficient pressure. After microwave energy has been applied to curing chamber 26 and the core cured, the fluid may be pumped out through piping 62, thus causing the ballon-like core box halves 58 and 60 to collapse whereby the cured core may be easily removed from the core box.
  • this embodiment enables an operator to blow cores which have undercut portions such as is shown in each corner of the chamber 56 in FIGURE 5.
  • metal core boxes of the prior art it has been possible to blow cores having undercut surfaces only by using extremely expensive sectionalized core boxes.
  • the present invention enables an operator to easily blow undercut cores while still meeting the advantages of a cheap core box, quick curing, and no intermediate handling.
  • valve plate normally closes the bottom of hopper 12.
  • Valve plate 20 is connected through a suitable linkage 64 to the piston in pneumatic cylinder 66.
  • Pneumatic cylinder 66 is connected to a source of compressed air 68.
  • valve plate 26 When it is desired to form a core, and thus to blow sand into the curing chamber, valve plate 26 is opened by opening valve 70, thus allowing compressed air into cylinder 66 which moves its piston to the right and opens valve plate 20, allowing a quantity of the sand and resin mixture to fall into the blowing chamber 28. Valve 70 is then closed and valve 72 is opened, thus moving the piston in cylinder 66 to its other extreme position and closing valve plate 20 again. Now valve 74 is opened and the compressed air supply 68 is connected to blowing chamber 18, in which chamber the compressed air forces the sand and resin mixture through the tubes 50 to the chamber 56 of core box 54. Next the microwave transmitter in console 48 is energized, microwave energy is supplied to the curing cavity 26, and, as was previously described, the core is cured.
  • Valve 74 is now closed and the hydraulic system 76 is activated so as to supply hydraulic fluid under pressure into line 78, thus forcing the piston in hydraulic cylinder 36 into its lower position thereby lowering lower platen 26 and enabling an operator to remove the cured core from the lower half of core box 54.
  • the hydraulic system 76 is now activated to supply fluid under pressure into line 80 to raise the piston of hydraulic cylinder 36 to its upper position, thereby closing lower platen 30 against upper platen 28 and the device is now ready to repeat the cycle and blow and cure another core.
  • the controls for the hydraulic and pneumatic portions of the device may conveniently be housed in console 48 along with the microwave transmitter therein. Indeed, in fully automated systems the above described cycle may be programmed into console 48, as is well known to those skilled in the control art, and the entire cycle may be effected merely by pushing a start button.
  • the above described cycle may be programmed into console 48, as is well known to those skilled in the control art, and the entire cycle may be effected merely by pushing a start button.
  • cores may be cured to a suitable degree of hardness to withstand normal handling with an application of about 20 seconds of microwave energy.
  • a single operator using the device as described can produce several cores a minute if the operating cycle is properly programmed. It is then only necessary for the operator to push a start button and to remove the cured core when the lower platen 30 is in its lower position.
  • the cycle begins with the platen in its lower position.
  • the start button is pushed, the platen is then raised, the sand and resin mixture blown into the core box, the microwave energy applied and the platen then lowered so that the operator may remove the cured core.
  • the operators hands are not placed between the platens during a portion of the cycle in which the platens are separated for only a fixed period of time and there is little likelihood that the operators hands will be caught between the closing platens.
  • the inner surfaces of the portions of the core box may be coated with any suitable ferrite material such as Mn Zn Fe O CuFe O or Ferrite materials, as is well known, exhibit lossiness because of their magnetic properties and thus when the sand and resin mixture is blown into a core box so coated the ferrite coating shields the sand and resin mixture from the microwave energy but is itself heated quite hot by the energy. This heat is then transferred by conduction to the outer surfaces of the sand and resin mixture and rapidly cures this outer surface.
  • any suitable ferrite material such as Mn Zn Fe O CuFe O or Ferrite materials
  • the cured outer shell even though it might have a thickness of only a sixteenth to an eighth of an inch has sufficient strength to enable the core to be handled, it is then possible to remove the core from the core box even though the curing has not completed in the inner portions of the core. Indeed, it may sometimes be desirable to so remove the core and to shake the re mainder of the sand and resin mixture out of the center of the core, leaving only a cured shell core.
  • One advantage of this embodiment is that the inner surface of the core box is maintained at a uniform temperature, thus assuring uniform curing of the core.
  • difliculty is frequently experienced when heat is unevenly drawn from the core box, thereby causing uneven temperature and inconsistent curing.
  • Another advantage of this embodiment is that when the ferrite material is heated to its Curie temperature point, it ceases to have magnetic properties and thus becomes essentially lossless to microwave energy. At this time, the surface of the core continues to receive heat by conduction from the hot ferrite coating but the microwave energy now passes through the ferrite coating and is converted directly into heat in the sand and resin mixture in a manner as was originally described. Thus, the core is no longer shielded by the ferrite lining and maximum rapid heating and curing of the core is effected. Also, a ferrite may be selected having a Curie temperature which is the optimum curing temperature of the particular resin being used.
  • the ferrite material may be mixed directly with the sand and resin mixture instead of being coated on the inner surface of the core box. This renders the mixture extremely lossy and causes rapid heating and thus curing of the core when microwave energy is applied to the mixture in the core box.
  • the ferrite material may be removed from the broken sand mixture by a simple magnetic separator and may be used again in the cycle.
  • a core box made from a material which is transparent to microwave energy
  • a microwave heating cavity means for supporting said core box in said cavity, means for blowing a core-forming material into said core box, and means for applying microwave energy to said cavity.
  • a core box made from a material which is transparent to microwave energy
  • a microwave heating cavity means for supporting said core box in said cavity, means for blowing a mixture of sand and a thermosetting resin into said core box, and means for applying microwave energy to said cavity.
  • a core box made from silicone rubber, a microwave heating cavity, means for supporting said core box in said cavity, means for blowing a mixture of sand and thermosetting resin into said core box, means for applying microwave energy to said cavity, and means for opening said cavity and core box to remove the cured core from within said core box.
  • a core box made from a material which is transparent to microwave energy, a ferrite lining on the interior surface of said core box, a microwave heating cavity, means for supporting said core box in said cavity, means for blowing a core-forming material into said core box, and means for applying microwave energy to said cavity.
  • a core box made from a material which is transparent to microwave energy, a ferrite lining on the interior surface of said core box, a microwave heating cavity, means for supporting said core box in said cavity, means for blowing a mixture of sand and thermosetting resin into said core box, and means for applying microwave energy to said cavity.
  • a core box made from a material which is transparent to microwave energy
  • a microwave heating cavity means for supporting said core box in said cavity, means for blowing a mixture of sand, thermosetting resin and ferrite material into said core box, and means for applying microwave energy to said cavity.
  • a core blowing device which'comprises, in combination, a hopper for receiving a mixture of sand and thermosetting resin, a blowing chamber, valve means connecting said hopper and blowing chamber, a microwave cavity, a lossless core box adapted to be supported in said microwave cavity, at least one conductive tube from said blowing chamber to the interior of said core box, means for applying air under pressure to said blowing chamber to force said mixture through said tube into the interior of said core box, means for applying microwave energy to said cavity, and means for opening said cavity and core box to remove the cured core from within said core box.
  • a core blowing device which comprises, in combination, a hopper for receiving a mixture of sand and thermosetting resin, a blowing chamber, valve means connecting said hopper and blowing chamber, a microwave cavity bounded by a plurality of relatively moveable sections, a lossless core box formed from an equal plurality of mating sections adapted to be supported in said microwave cavity, at least one conductive tube from said blowing chamber to the interior of said core box, means for applying air under pressure to said blowing chamber to force said mixture through said tube into the interior of said core box, means for applying microwave energy to said cavity, and means for opening said cavity and core box to remove the cured core from within said core box.
  • a core blowing device which comprises in combination a hopper for receiving a mixture of sand and thermosetting resin, a blowing chamber, valve means connecting said hopper and blowing chamber, a microwave cavity bounded by a plurality of relatively moveable sections, a lossless core box formed from an equal plurality of mating sections adapted to be supported in said microwave cavity, each of said mating sections being attached to a respective one of said sections bounding said cavity, at least one conductive tube from said blowing chamber to the interior of said core box, means for applying air under pressure to said blowing chamber to force said mixture through said tube into the interior of said core box, means for applying microwave energy to said cavity, and means for separating said sections bounding said cavity, thereby opening said core box, to remove the cured core from within said core box.
  • a core blowing device which comprises in combination a hopper for receiving a mixture of sand, thermosetting resin and ferrite material, a blowing chamber, valve means connecting said hopper and blowing chamber, a microwave cavity bounded by a plurality of relatively moveable sections, a lossless core box formed from an equal plurality of mating sections adapted to be supported in said microwave cavity, each of said mating sections being attached to a respective one of said sections of said cavity, at least one conductive tube from said blowing chamber to the interior of said core box, means for applying air under pressure to said blowing chamber to force said mixture through said tube into the interior of said core box, means for applying microwave energy to said cavity, and means for separating said sections bounding said cavity, thereby opening said core box, to remove the cured core from within said core box.
  • a process for making cores which comprises the steps of forming a core box from a material which is lossless to microwave energy, blowing a lossy coreforrning material into said core box, and applying microwave energy to said core box.
  • a process for making cores which comprises the steps of forming a core box from a material which is lossless to microwave energy, blowing a mixture of sand and thermosetting resin into said core box, and applying microwave energy to said core box.
  • a process for making cores which comprises the steps of forming a core box from a material which is lossless to microwave energy, blowing a mixture of sand and thermosetting resin into said core box, applying microwave energy to said core box, and removing the cured core from said core box.
  • a process for making cores which comprises the steps of forming a core box from a material which is lossless to microwave energy, coating the interior surface of said core box with a lining of ferrite material, blowing a lossy core-forming material into said core box, and applying microwave energy to said core box.
  • a process for making cores which comprises the steps of forming a core box from a material which is los'slss to microwave energy, coating the interior surface of said core box with a lining of ferrite material, blowing a mixture of sand and thermosetting resin into said core box, and applying microwave energy to said core box.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
US457747A 1965-05-21 1965-05-21 Method and apparatus for blowing cores using microwave energy Expired - Lifetime US3429359A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
US457747A US3429359A (en) 1965-05-21 1965-05-21 Method and apparatus for blowing cores using microwave energy
FR60408A FR1478864A (fr) 1965-05-21 1966-05-05 Procédé et appareil de soufflage de noyaux pour des moules de fonderie
BE680552D BE680552A (fr) 1965-05-21 1966-05-05
DE19661508676 DE1508676B1 (de) 1965-05-21 1966-05-11 Vorrichtung zum herstellen eines zum giessen eines metallgussstueckes geeigneten formkoerpers oder kernes mittels mikrowellenergie
GB21973/66A GB1132373A (en) 1965-05-21 1966-05-17 The production of moulds and cores for metal castings
NL6606859A NL6606859A (fr) 1965-05-21 1966-05-18

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US457747A US3429359A (en) 1965-05-21 1965-05-21 Method and apparatus for blowing cores using microwave energy

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US3429359A true US3429359A (en) 1969-02-25

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US (1) US3429359A (fr)
BE (1) BE680552A (fr)
DE (1) DE1508676B1 (fr)
FR (1) FR1478864A (fr)
GB (1) GB1132373A (fr)
NL (1) NL6606859A (fr)

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US3535481A (en) * 1969-03-24 1970-10-20 Plastics Eng Co High frequency induction heating of semiconductive plastics
US3539751A (en) * 1966-10-26 1970-11-10 Melvin L Levinson Insulating implement for use in a microwave oven
US3569657A (en) * 1969-09-16 1971-03-09 Melvin L Levinson Method of processing and transporting articles
US3594531A (en) * 1969-11-10 1971-07-20 Ralph L Hough Internally viewable microwave induction heater
US3692085A (en) * 1970-05-08 1972-09-19 Lloyd H Brown Process for producing cores by microwave heating
US3701872A (en) * 1968-02-09 1972-10-31 Melvin L Levinson Heating and loading implement for microwave energy
US3847202A (en) * 1973-03-02 1974-11-12 Trw Inc Microwave dewaxing
US3937774A (en) * 1972-11-22 1976-02-10 Allied Resin Corporation Flow molding means and method
US4221752A (en) * 1977-03-03 1980-09-09 Shells, Inc. Plant receptacle and method of producing same
US4330698A (en) * 1979-04-21 1982-05-18 Doryokuro Kakunenryo Kaihatsu Jigyodan Microwave melter
DE3605392A1 (de) * 1986-02-20 1987-08-27 Siempelkamp Gmbh & Co Verfahren zur herstellung einer dickwandigen giessform aus giessereisand
US4940865A (en) * 1988-10-25 1990-07-10 The United States Of America As Represented By The Department Of Energy Microwave heating apparatus and method
US5281784A (en) * 1993-01-04 1994-01-25 Kuhn James O Mold assembly for microwave oven
WO1994016541A1 (fr) * 1993-01-04 1994-07-21 Kuhn James O Ensemble moule pour four a micro-ondes
US5587099A (en) * 1993-12-13 1996-12-24 Kuhn; James O. Safety container for microwave oven baking utensil
US5653778A (en) * 1991-12-09 1997-08-05 U.S. Philips Corporation Molding device comprising microwave generator and a microwave oven
US6013125A (en) * 1995-09-13 2000-01-11 Quraishi; Mashallah M. Investment of powders and method for rapid preparation of investment molds
US20040149416A1 (en) * 2003-02-04 2004-08-05 Siak June-Sang Method of sand coremaking

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CA1049251A (fr) * 1973-06-25 1979-02-27 Edward C. Dench Produits a teneur de magnetite pour favoriser la cure aux micro-ondes
DE2844222C2 (de) * 1978-10-11 1984-10-18 Gewerkschaft Eisenhütte Westfalia, 4670 Lünen Verfahren und Einrichtung zum Verbinden von Anoden mit ihren Anodenstangen
JPS6059064B2 (ja) * 1981-03-17 1985-12-23 株式会社小松製作所 マイクロ波加熱硬化鋳型用模型の製造方法
DE102011101434A1 (de) 2011-05-16 2011-12-15 Daimler Ag Verfahren zum Herstellen einer Form
CN108666133A (zh) * 2018-05-17 2018-10-16 东莞市威庆电子有限公司 一种pp塑料外壳电容及其制作工艺
CN108723353B (zh) * 2018-08-08 2024-02-27 安徽新宁装备股份有限公司 砂型套箱拆除清理机构

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US2517902A (en) * 1944-08-31 1950-08-08 George C Luebkeman Molding process and means
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US3539751A (en) * 1966-10-26 1970-11-10 Melvin L Levinson Insulating implement for use in a microwave oven
US3701872A (en) * 1968-02-09 1972-10-31 Melvin L Levinson Heating and loading implement for microwave energy
US3535481A (en) * 1969-03-24 1970-10-20 Plastics Eng Co High frequency induction heating of semiconductive plastics
US3569657A (en) * 1969-09-16 1971-03-09 Melvin L Levinson Method of processing and transporting articles
US3594531A (en) * 1969-11-10 1971-07-20 Ralph L Hough Internally viewable microwave induction heater
US3692085A (en) * 1970-05-08 1972-09-19 Lloyd H Brown Process for producing cores by microwave heating
US3937774A (en) * 1972-11-22 1976-02-10 Allied Resin Corporation Flow molding means and method
US3847202A (en) * 1973-03-02 1974-11-12 Trw Inc Microwave dewaxing
US4221752A (en) * 1977-03-03 1980-09-09 Shells, Inc. Plant receptacle and method of producing same
US4330698A (en) * 1979-04-21 1982-05-18 Doryokuro Kakunenryo Kaihatsu Jigyodan Microwave melter
DE3605392A1 (de) * 1986-02-20 1987-08-27 Siempelkamp Gmbh & Co Verfahren zur herstellung einer dickwandigen giessform aus giessereisand
US4940865A (en) * 1988-10-25 1990-07-10 The United States Of America As Represented By The Department Of Energy Microwave heating apparatus and method
US5653778A (en) * 1991-12-09 1997-08-05 U.S. Philips Corporation Molding device comprising microwave generator and a microwave oven
US5281784A (en) * 1993-01-04 1994-01-25 Kuhn James O Mold assembly for microwave oven
WO1994016541A1 (fr) * 1993-01-04 1994-07-21 Kuhn James O Ensemble moule pour four a micro-ondes
US5396051A (en) * 1993-01-04 1995-03-07 Kuhn; James O. Safety container for mold assembly in microwave oven
US5587099A (en) * 1993-12-13 1996-12-24 Kuhn; James O. Safety container for microwave oven baking utensil
US6013125A (en) * 1995-09-13 2000-01-11 Quraishi; Mashallah M. Investment of powders and method for rapid preparation of investment molds
US20040149416A1 (en) * 2003-02-04 2004-08-05 Siak June-Sang Method of sand coremaking
US6843303B2 (en) * 2003-02-04 2005-01-18 General Motors Corporation Method of sand coremaking

Also Published As

Publication number Publication date
GB1132373A (en) 1968-10-30
FR1478864A (fr) 1967-04-28
NL6606859A (fr) 1966-11-22
BE680552A (fr) 1966-11-07
DE1508676B1 (de) 1970-01-02

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