US1834555A - Knife - Google Patents

Description

H. w. TrrTLE KNIFE v Filed Dec. l2, 1929 Patented Dec. l, 1931 UNITED STATES PATENT OFFICE HARRY W. TITTLE, F AKRON, OHIO, ASSIGNOR TO THE B. F. GOODRICE COMPANY. 0F NEW YORK, N. Y., A CORPORATION OF NEW YORK KNIFE Application led December 12, 1929. Serial No. 413,509.

This invention relates to knives and more cspcciall y to hand operated, electrically heated cutting tools which may be usefully employed in the rubber industry for cutting rub ber sheets.

The chief object of the invention is to provide au improved electrically heated knife of convenient size, Weight, and shape for manual handling. Other objects will be manifest.

Of the accompanying drawings:

Fig. l is a perspective view of my improved knife, in its preferred form, in atypical operative association with the work.

Fig. 2 is a longitudinal section through the knife.

Fig. 3 is a section on line 3 3 of Fig. 2.

Fig. 4 is a section of line 4 4 of Fig. 2.

Referring to Fig. 2 of the drawings, the knife comprises a handle of Wood or other' dielectric and heat resisting material and a blade 11 of loop form and of suitable electric resistance metal such as nichrome steel adapted to be heated by electric current supplied thercto by a pair of electrodes 12, 13. The latter are composed of electrically conductive metal, of low electrical resistance, in the form of cylindrical rods which are mounted in respective longitudinal bores in the handle 10. The electrodes l2, 13 project beyond one end of the handle and support the blade 11 which is attached at one of its ends to both electrodes in any suitable manner, preferably b slotting the electrodes and welding the lade in the slots, as isiclearly shown in Fig. 3. The other ends of the electrodes 12, 13 are disposed within the handle 10 and to them are secured respective electrical conductors 14, 15 of a flexible cable 16 having connection with a suitable source of electric current (not shown).

The blade 11 preferably has a rounded point at its end remote from the handle 10 and preferably has both lateral edges sharpened adjacent its pointed end. The blade is formed with a longitudinal slot 17 which eX- tends from its attached end between the electrodes 12, 13 to a point adjacent its opposite end. Thus the blade is formed as a generally U-shaped structure or loop having a sharpened outer edge and having a point at the outer end of the loop. The knife is wider and thicker at its rear end than at its forward, sharper end, with the result that the latter has greater resistance to electrical current and consequently attains the greatest heat. y

A typical example of the use for which my improved knife is especially adapted is illust-rated in Fig. 1 of the drawings, in which 18 is a sheet of unvulcanized rubber and 19 is a template of metal laid thereon, the rubber being severed by drawing the pointed end of the knife thereover while guiding it by contact with the edge of the template. Used in the manner described, the knife requires to be heated only to a dull redness to melt the rubber, and such heating of the blade may be effected with electric current of relatively low voltage, say 2 or 3 volts, at 40 amperes.

The pointed end of the blade permits the accurate cutting of intricate designs from the rubber sheet 18, and the sharp lateral edges of the blade may be utilized for cutting simpler designs or for cutting thicker sheets of rubber. Because the blade is not heated to incandescense, itis not subject to oxidation with resultant rapid dulling of its cutting edge. Consequently frequent sharpenin is avoided, and wetting of the blade, to lu ricate the same, is not required.

By heating the blade directly as a result of its own resistance, instead of by conduction from a heating element, I provide a tool of lighter Weight and having greater convenience of handling. The blade may be heated with substantial uniformity throughout its structure, and its point, which is the portion subject to greatest use, may be kept uniformly hot.

The invention is susceptible of modification within the scope of the appended claims.

I claim:

1. In a cutting tool the combination of a handle, a blade supported thereby and comprising a generally U-shaped structure of high resistance metal having a sharpened edge terminating at a cutting point, and electrical conductors connected with the respective legs of the U-shaped structure, the electrical resistance of the blade being greater near the point. f

2. In a knife the combination of a handle, a cuttin blade supported thereby and formed of a re atively hard alloy capable of maintaining a cutting edge with a longitudinal slot open at one end of the blade, and elecJ trical conductors attached to said blade at opposite sides of said slot, said blade being provided with a plurality of sharp edges terminating in a pomt.

In Witness whereof I have hereunto set my hand this 6th day of December, 1929.

HARRY W. T ITTLE.

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