DONALD ELI WITKIN
Engineers in Warren, PA

3931382, Jan 6, 1976

Jan 27, 1975

5/544646

Donald E. Witkin - Warren PA

National Forge Company - Irvine PA

B29F 304

264 88

Method for compacting preheated powder bodies in a high pressure isostatic pressure vessel in which a liquid such as water is used as the pressurizing medium. A preheated workpiece is inserted into the vessel which is closed and sealed. The vessel is then rapidly filled with the liquid pressurizing medium while avoiding contact of the medium with the preheated workpiece until the vessel is substantially completely full. The pressure within the vessel is then increased rapidly to a preselected compacting level by continually pumping the liquid pressurizing medium into the vessel. The preselected compacting pressure is in excess of the critical pressure of the liquid pressurizing medium. The rapid increase of pressure within the vessel to a level exceeding the critical pressure minimizes the amount of vapor that is formed in the vessel and reduces heat transfer from the preheated body to the pressurizing system. In a preferred embodiment, avoidance of contact of the pressurizing medium with the preheated workpiece until the vessel is substantially completely filled is accomplished by the use of a shielding container.

4066868, Jan 3, 1978

Jul 7, 1975

5/593709

Donald E. Witkin - Warren PA
Arnold G. Bowles - Warren PA

National Forge Company - Irvine PA

H05B 102

219486

The disclosed invention describes an apparatus and method for bringing a system having high interactive portions to a predetermined temperature distribution. The invention includes a difference controller which provides, through two separate drivers, a fixed total amount of energy to the system being controlled. If the system being controlled also has a long cycle time, second and third temperature controllers may be used to bring the system to the equilibrium temperature with a minimum amount of overshoot. The invention is particularly advantageous when used in connection with a high pressure, high temperature vessel useful in growing quartz crystals.

4013394, Mar 22, 1977

Aug 18, 1975

5/605416

Donald E. Witkin - Warren PA
Arnold G. Bowles - Warren PA

National Forge Company - Irvine PA

B29C 300, B22F 300

425405H

The invention relates to means for establishing an equalized pressure across the insulating sheath of a hot isostatic press system. Tubes are positioned in the outer, insulation portion of the sheath to provide a substantially resistance free passage between a source of high pressure gas input to the system and the upper portions of the sheath. The invention also tends to reduce convection currents in the furnace chamber.

4011430, Mar 8, 1977

May 6, 1975

5/574961

Donald Eli Witkin - Warren PA
Andrew Stephenson Dalgleish Crum - Warren PA

National Forge Company - Irvine PA

H05B 102

219486

In a multizone electrical furnace the phase shift effect of the thyristor devices used to control the power supplied to each thermal zone is reduced by providing two or more heater circuits, each including a thyristor device and a heating element, for each thermal zone. The thyristor devices are controlled so that only one thyristor device associated with each thermal zone is operating to produce a substantial phase shift at any time. Over-powering the heating elements at higher furnace temperatures may also be prevented by connected two or more heating elements associated with a thermal zone to one of the thyristor devices associated with that zone above a predetermined threshold temperature.

3971876, Jul 27, 1976

Jul 3, 1975

5/592888

Donald E. Witkin - Warren PA
Arnold G. Bowles - Warren PA

National Forge Company - Irvine PA

H05B 102

13 31

The disclosed invention describes an apparatus and method for bringing a system having high interactive portions to a predetermined temperature distribution. The invention includes a difference controller which provides, through two separate drivers, a fixed total amount of energy to the system being controlled. If the system being controlled also has a long cycle time, second and third temperature controllers may be used to bring the system to the equilibrium temperature with a minimum amount of overshoot. The invention is particularly advantageous when used in connection with a high pressure, high temperature vessel useful in growing quartz crystals.