US1661797A - Can opener - Google Patents

Description

March 6, 1928. 1,661,797 H. GARRISON CAN OPENER Filed March '7, 1927 Ill/I Patented Mar. 6, 1928.

UNITED STATES A 1,661,797 PATENT orr ce.

HERMAN GARRISON, or CHICAGO, ILLINOIS.

CAN OPENER.

Application filed March 7, 1927. Serial No. 173,233.

The subject of this application is a certain improvement in that type of can opener which isin most common use, and which may be described as a can opener designed to operateas a leverof the second class, having a guiding fulcrum at the end of its stock, and an offset uppercut knife.

The result sought by this improvement is,

to facilitate the use of a longer knife than is at present employed on openers of this type.

it is obvious that if a lengthened knife is I to be applied to circular cans, it mustbe curved to conform somewhat to the contour of the can. We are then confronted with the problem of fitting a knife of fixed curvature to cans of different curvatures. If we adopt the curvature of a small can and attempt to use the knife on a large can, we meet with two insurmountable difficulties; the successive kerfs, being arcs of" a smaller circle than that which forms the contour of the can,'will make a jagged and imperfect edge, and the knife, on accountof its great curvature, will have a tendency to buckle under direct pressure applied to produce penetration. It is desirable to reduce the curvature as far as may be practicable. The specific object, then, of this invention is to modify a knife having the curvature of a large can, so as to adapt it to operation on a small can. i

Fig. 1 is a side view of the opener, showing stock A fitted into a handle, and knife B riveted to the stock, and provided with upper and lower cutting edges shown by double lines, the lower cutting edge being requisite to the introduction'of a lengthened knife. The upper cut-tingedge is made rearwardly concave in outline. The point C is at the beginning of the cutting edge, but not necessarily adjacent to the stock. The upper rearward part of the heel of the knife is bent forward, the shank above being bent back again for its attachment to the straight stock. This invention is not, however, concerned with the upper partof the shank, nor with the mode of its attachment to the stock, but only with the opera: tive partof the knife, which is inserted into .the can.

Fig. 2 is a partial top plan view, showing the strip metal stock A bent aside to form "the fulcrum member D, and showing the lateral curvature of the knife, set to a radius of 2 inches. The spreading of the kit line of contour at the base of the knife, adjacent'to the point C, is occasioned by a peculiar flexure of the heel which will be explained in connection with subsequent figures.

Fig. 3 is a view of thefront end of the instrument, showing the vertical face of the fulcrum member 1), and the notch E, which forms the fulcrum. i

Fig. 4 represents a-partial circumference of can 3 inches'in diameter, and shows how a knifev having the curvature of the knife or Fig. 2, but in the form OI an un-,

modified circular arc, will fit into such a can.

Fig. 5 is 'a top plan view of the knife of Fig. :2, when fitted into a can 3 inches in di ameter. r i

Fig. 6 is a partial side viewof the-knife;

showing the line of flexion Fla which crosses the heel. I

Fig. 7 exhibits a vertical-section of the heel and adjoining part. of the shank. Fig. 8, which will bebetter understood after an explanation which will lead to it, shows the relative operative position of cer tain elements, a detailed description of which will be given later.

Reverting to Fig. 4:, the point C, Figs. 1, 2 and 4., at which the cutting edge begins, will be too far from the rim to permit of successful operation. 'VVe must move it up close to the rim.

The most obvious method ofdoing this is to bend the heel forward on a vertical line through the point C,'but a better way will be to bend the heel forward on the line Fla, Fig. 6.

Fig. 7 will then show a line 7 7 of Fig. 6. r i

The instrument will be operated on a bias, its position being set by rotating the handle slightly clockwise. Reference to section on the Fig. 7 will show that the bending'of the" heel is an aid to placing the knife in this desired position. The width of the uncut annular area adjacent the rim is determined by the lateral displacement of the fulcrum. In using a knife of the length here shown, it is necessary to set the fulcruinso as to cut close to the rim, else there will be developed a tendency, sometimes met with in can openers of inferior make to puller raise the tin instead of shearing it.

If we place the fulcrum so far to the lef as'to bring it in line with the knife, the

pressure of the knife point against the wall of the can will resist our efforts to place the notch on the crimp. By bending the heel and moving point C to the rim, we move the point of the knife to the left and diminish its resistance.

It is not necessary for the operator to set the knife on the bias; it is forced into that position by the pressure of the knife on the wall of the can, and the fulcrum, instead of being at the summit of the notch, is at the left of it. The relative positions of parts concerned are illustrated by a diagram, Fig. 8. This shows in part a sectional view of a can, and the face of the fulcrum member D, as we look forward toward the point of the knife, with the notch resting on the crimp. M is a section of the knife. This shows how the instrument is forced by the adjustment of knife and fulcrum to operate on the bias, this being its position of equilibrium.

It will now be seen that the path of the incision will conform to the contour of the can with its radius of 11/ inches, instead of following the lateral curvature of the knife with its radius of 2% inches, as it would if the knife were operated in its normal position.

We have, therefore, adapted a knife of fixed curvature to a can of greater curvature.

The cooperation just illustrated between the two curves of the knife edge and the curve of the can would be geometrically im' possible if the point C were not brought into a location contiguous to the rim at thebeginning of each kerf.

There is, therefore, a closely cooperative function in which three distinct elements of knife structure participate: the lateral curvature of the knife, the concave curve of the upper edge, and the flexure of the heel. I have seen the first two of these elements in manufactured can openers, and examples of them are found in certain patents; but the combination of the three for the purpose herein set forth is believed to be novel.

Having thus described my inventioinv'hat I claim as new and desire to secure by Letters Patent is: v

1. A can opener in the form of a lever of the second class, having a guiding fulcrum formed by a recess at the end of a handled stock, and a downwardly offset upper cut knife secured to the stock and extending forward past the fulcrum: said knife being laterally curved in the direction of its length and provided with an additional cutting edge on its lower margin, and having its upper cutting edge rearwardly concave in outline; the heel of said knife being marked by a line of flexion transverse to the longitudinal direction of the instrument, and that part of said heel which is adjacent to said line of flexion and posterior thereto, being deflected toward the concave side of the directional curve ofrthe knife.

2. A can opener in the form of a lever of the second class, having a guiding fulcrum formed by a recess at the end of a handled stock, and a downwardly offset uppercut knife secured to the stock and extendin forward past the fulcrum; said knife being laterally curved in the direction of its length and provided with an additional cutting edge on its lower margin, and having its upper cutting edge rearwardly concave in outline; the upper rearward portion of the heel of said knife being deflected from a vertical position, and the direction of the displacement of the said deflected portion being towards the inner side of the directional curve of the knife.

3. Acan opener in the form of a lever of the second class, having a guiding fulcrum formed by a recess at the end of a handled stock, and a downwardly offset uppercut knife secured by its shank to said stock and extending forward past the uiding fulcrum; said knife being lateral y curved in the direction of its length and provided with an additional cutting edge on its lower margin, and having its upper cutting edge rearwardly concave in outline; and the cutting blade of said knife being laterally offset from its shank by means of a curved jog, said curved jog being disposed transversely with respect to a line of flexion extending diagonally upward and forward from the outer rim of the heel of the knife, and the direction of displacement of the offset cutting blade being away from the center of curvature of the directional curve of the knife.

4. A can opener in the form of a lever of the seeond class, having a guiding fulcrum formed by a recess at the end of a handled stock, and a downwardly offset uppcrcut knife secured by its shank to said stock and extending forward past the guiding fulerum; said knife being laterally curved in the direction of its length and provided with an additional cutting edge on its lower margin, and having its upper cutting edge rearwardly concave in outline; and the cutting blade of said knife being laterally offset from its shank by means of a curved jog, the offset portion being rearwardly bounded by a line of flexion extending diagonally down ward and backward from the rearward portion of the upper edge of the knife, and the direction of displacement of the offset cutting blade bein outward from the center of curvature of t e directional curve of the knife.

HERMAN GARRISON.

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