Hot wire cutting system
OwnerWilliam T. Clark, IIIinventor
Life of this patent
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Abstract
A hot wire cutting system for cutting a pattern shape in a block of polyfoam for use as a casting mold for a metal shielding block to be used in radiotherapy treatments is described. The system provides proportioned current responsive to deflection of the hot cutter wire in order to cancel the deflection and maintain the wire in its optimal central cutting position. The hot cutter-wire preferably passes through a field which provides fine vibratory motion of the cutting wire allowing use of lower wire temperatures to effect the cutting. The system may include optical means for determining the accuracy of the profile cut in the polyfoam block.
Claims9
A hot wire cutting stystem comprising,
- a heating wire adapted to be supported under tension at opposite end portions in a position for said wire to be engaged by material being cut, wherein a force applied by uncut material against the wire displaces said wire from a normal position,
- power circuit means for supplying heating current to said wire,
- said power circuit means being adapted to be connected to a source of electrical power and including control means for respectively increasing and decreasing the heating current supplied to the wire,
- sensing means responsive to the deflection of said wire from said normal position for producing an error signal representative of the estent of said deflection,
- said control circuit means being responsive to said error signal for respectively increasing and decreasing the heating current supplied to said wire representative of extent of said deflection.
A hot wire cutting system comprising, a
- heating wire adapted to be supported under tension at opposite end portions in a position for said wire to be engaged by material being cut, wherein a force applied by uncut material against the wire displaces said wire from a normal position,
- power circuit means for supplying heating current to said wire,
- said power circuit means adapted to be connected to a source of electrical power including switch means actuatable between "on" and "off" conditions for respectively increasing and decreasing the heating current supplied to the wire,
- sensing means responsive to the deflection of said wire from said normal position for producing an error signal representative of said deflection, and
- control circuit means for actuating said switch means to said "on" condition in response to said error signal,
- said control circuit means including means for establishing a threshold voltage required to control said switch to its "on" condition,
- said control circuit means further including integrating means for accumulating charges of said error signal so as to maintain said threshold voltage for a predetermined time after said error signal has ceased, whereby the "on" time of said switch is maintained throughout a series of rapidly occurring deflections of said wire from its normal position.
A hot wire cutting system comprising,
- a heating wire,
- means for supporting opposite end portions of the wire in a normal position for said wire to be engaged by the material to be cut wherein force supplied by uncut material against the wire deflects the wire from the normal position,
- a source of alternating current including a power supply circuit having opposite sides for energizing the wire,
- sensing means responsive to the displacement of said wire from said normal position for producing a signal representative of the extent of said deflection,
- means responsive to said signal for connecting the wire across the opposite sides of said power supply circuit and thereby energizing the wire,
- and means for creating a magnetic field through which said heating wire passes, whereby said wire constitutes a transducer and vibrates when energized by said alternating current.
Dependencies are inferred from the claim text.