US2728140A - Scissors with twisted blades having unimpeded surfaces - Google Patents

Description

Dec. 27, 1955 E. KRUSIUS 2,723,140

SCISSORS WITH wwzsmn BLADES HAVING UNIMPEDED SURFACES Filed Dec. 5, 1951 3 Sheets-Sheet 1 5p [3 IN V EN TOR. EI ZI/ZFZ If!" a. at;

CQJ W E. KRUSIUS Dec. 27, 1955 SCISSORS WITH TWISTED BLADES HAVING UNIMPEDED SURFACES 3 Sheets-Sheet 2 Filed Dec. 5, 1951 I JNVENIOR. Erwzn Kz zuzzzw Dec. 27, 1955 E. K'RUSIUS 2,728,140

SCISSORS WITH TWISTED BLADES HAVING UNIMPEDED SURFACES Filed Dec. 5, 1951 3 Sheets-Sheet 3 W @Q'y-ffl. a fzy. 9

/7/J ATTORNEY SCISSORS WITH TWISTED BLADES HAVING UNIMPEDED SURFACES.

Erwin Krusius, Solingen, Germany Application December '5, 1951, Serial No. 259,953 Claims priority, applicationGermany December 6, 1950 1 Claim. c1. 30-268) This invention relates to scissors having two pivoted blades with a resilient element therebetween.

The cost of manufacture of conventional scissors largely depends upon the number of the grinding, or glazing or polishing operations, necessary. The usual operations at present comprise:

(1) Grinding of the inner surfaces of the-bladesfrom the points to the pivots in order to provide the same with a sharp edge and with a twist to improve the cutting power,

(2) Grinding of the inner surfaces of the blades between the pivot and the finger bows or their shanks in order to give the surfaces a convex shape (usually called the half-moon) so that the engagement of the half-moons on the adjacent blades during a cutting operationfcauses the edges of the blades to frictionally slide one along the other at their point of intersection,

(3) Grinding of the shoulders where the finger bows or their shanks join the inner surfaces of the blades,

(4) Grinding of the shanks to an oval, round or faceted cross section,

(5 Grinding of the outer surfacesof the blades in the vicinity of the pivot in twoor three different operations, owing to the shape of the outer surfaces,

(6) Grinding of the outer surfaces of the blade from the points to the vicinity of the pivot in three or four operations, necessary owing to the faceted or round form usual in scissors. y

The grinding of scissors has remained very complicated owing to the several grinding operations necessary to produce the half-moon oneach blade- It is a main object of this invention to reduce the number of different grindingbperations, thereby lowering the production costs of the .scissors.

According to the invention, there is provided a pair of scissors comprising two blades, each of which has a smooth continuous inner surface extending from the point to a position adjacent the finger bow which surface is ground, or glazed or polished ina single operation, and a resilient element is inserted between the pivot and the finger bow of a blade.

Each blade may have at least one smooth continuous outer surface from the point to a position adjacent the finger bow, which surface is also ground, glazed or polished in a single operation. 7

In this case, the inner surface and. one outer surface of each blade may be ground, or glazed or polished simultaneously in a single operation.

In order that the invention may be more clearly understood, several embodiments thereof will now be described by way of example and with reference to the accompanying drawings wherein:

Fig. 1 is a plan view of a pair of scissors, according to the invention, in the open position, a

I Fig. 2 is a transverse cross section, to an enlarged scale, of a blade on the line II-II of Figure 1,

Fig. 3 is a transverse cross ,section, to an enlarged U it St t s P w 2,728,140 Patented Dec. 27, 1955 ICC scale, of a blade and the resilient insert on the line III- III of Fig. 1,

Figs. 4 to 8 illustrate various forms of scissors according to the invention,

Fig. 9 illustrates a modified pair of scissors according to the invention, in the closed position,

Fig. 10 is a transverse cross section to an enlarged scale of a blade and the resilient insert on the line X--X of Fig. 9,

Fig. 11 is a longitudinal cross section to an enlarged scale taken on line XI-XI of Fig. 9,

Fig.v 12 shows a pair of scissors blades according to the invention with a modified form of the resilient insert,

Fig. 13 is a transverse cross section taken on the line XIII-XIII of Fig. 12,

Fig. 14 is a longitudinal cross section taken on the line XIV-XIV of Fig. 12.

The pair of scissors illustrated in Figs. 1 to 3 comprises two substantially similar scissors blades. The inner surface 1 of each blade is smooth and continuous from the point 2 to a position 5 adjacent the finger bow 4 and this surface can be ground, or glazed or polished in a single operation. From the position 5 the surface continues evenly into the shank of the finger bow at 3. The inner surfaces of the blades between the points and the bows are provided with a twist as shown in Fig. 2.

The outer surfaces 7 of the blades are rounded. The back edge 8 of each blade is faceted to reduce its sharpness.

A thin arcuate sheet metal 9 is inserted between the pivot screw 6 and the finger bows 4. The insert 9 has a convex outer shape in both the transverse and the longitudinal directions. The end 10 of the insert 9 is extended downwardly into a depression 11 in the inner surface of one of the blades and is held in place by the pivot screw 6 which passes through a hole 12 therein. When the scissor blades are closed the insert 9 is forced downwardly towards the inner surface 1 of the lower blade, reference being had to Fig. 1, and also presses against the inner surface of the other blade so that the cutting edges of the blades frictionally engage one another at their intersection.

The surfaces 1 and 7 of the blades can be ground, or glazed or polished in a single operation so that these operations can be effected on automatic grinding machines instead of being effected by hand.

The inner surface 1 of the scissors blade can be ground on a continually moving grinding surface by moving the blade, fixed in a holder, over the grinding surface. This permits the grinding of a number of scissors blades in one holder at the same time.

The pair of scissors shown in Fig. 4 has two blades, each inner surface 1 of which joins the finger bows 4 at shoulders 13, so that a completely smooth surface is obtained from the shoulders 13 adjacent the finger bow to the point 2.

In the scissors illustrated in Fig. 5, the pivot screw 6 is located as close as possible to the finger bows 4, so that substantially the entire section of the inner surface 1 between the screw 6 and the finger bows 4 of at least one of the blades is occupied by the insert 9. As the pivot screw 6 is brought closer to the finger bows 4, the length of the cutting edges of the scissors is increased as compared with the length of cutting edges of scissors illustrated in Figs. 1, 4, 6, 7, 8 and 9. The angle between the cutting edges of the blades is rendered substantially constant throughout. the cutting operation by making the cutting edges of arcuate form.

The scissors shown in Figure 6 have blades with outer surfaces which are not rounded. Each outer surface comprises three facets 7a, 7b and 70 running from the point .3 2 to theshoulder 13where the blade joins the finger bow 4. Each of these facets can be ground, or glazed or polished in a single operation.

The scissors shown in Fig. 7 have blades each of whose outer surfaces is of roof shape, that is to say the outer surface slopes gently away at 15 from the cutting edge and slopes sharply at 16 down to the back edge. Each of these portions of, the outer surfaces of the blade can be ground, or glazed or polished in a single operation.

The scissors shown in Figure 8 have blades whose outer surfaces are symmetrically divided into two equally sloping facets 17 and 18.

In each case, the inner surface of each blade is ground, or glazed or polished in a single operation.

Each pair of scissors shown in Figs. 4, 6, 7 and 8 includes a resilient insert 9, such as illustrated in Figs. 1 and 5.

The pair of scissors shown in Figure 9 has blades whose inner surfaces 1 are hollow ground, as shown in Figure 10. ground as shown in Figure 10 and a roof shape is given to the outer surface by the narrower surface 19. Each surface 1, 7 and 13 extends from the point to the shoulder 13 where it joins the finger bow 4. As in the scissors illustrated in Figure l, the insert comprises a piece of steel 9 having the end it) turned down into a depression 11 in the blade (see Fig. 11).

in the scissors illustrated in Figure 12, the insert 9 comprises a member 10 inserted in the inner surface of each blade between the pivot screw 6 and the finger bow. i

The member 10 has an outer convex surface to engage the outer convex surface of a corresponding member in the other blade of the pair of scissors during a cutting operation. The member 10 is made of a wear-resisting material, for example, hardened steel or other metal, stone, glass or ceramic. This member can be secured in the blade in any convenient manner, for example, by welding, soldering, brazing or glueing.

it will be understood that the resilient insert for a pair of scissors according to the invention may be on one or both blades.

The surfaces 1 and 7 of the blades of the scissors illus trated in Figures 9 and 12 may be hollow ground by passing the scissors blades between two shaped grinding wheels of a grinding machine so that the two surfaces are rollow ground, or glazed or polished in a single opera tion. The surface 19 may be ground, or glazed or polished either before or after the grinding of the surfaces 1 and 7.

In Fig. 12, the position of an insert 10 is shown in dotted lines. Figs. 13 and 14 show two inserts 10, one facing the other in the inner surfaces of adjoining scissors blades.

The scissors illustrated in Figures 1, 4, 6, '7, 8, 9, and 12 each have blades which are of substantially constant transverse cross-section throughout the length of the blade from its point to the junction of the blade with the finger bow. Thus, the blades may be hardened over their entire length up to the finger bows in one operation without causing warping which usually occurs and is caused by the sudden changes in cross-section which are usual in conventional scissors blades. The finger bows or eyes may also be hardened at the same time to reduce the number of operations upon the scissors during manufacture.

The foregoing description explains the invention to a man skilled in the art. Since the invention departs radically from the prior commercial practice, the following explanatory paragraph is added:

For example, a scissor blade is forged and is then subjected to a pressure action to provide a twist. The twisted blade is then hardened, which, as is known, causes an accumulation of scales on its surfaces. Instead of a special hand grinding of each blade from its tip to about the pivot hole, and to about the known: protuberance, the

so-called half-moon," which heretofore also required- The outer surface 7 of each blade is also hollow i spe ial head. ind ng th rindin tgnt yidethepdss is now carried out in one operation from the tip of the blade to the handle, the shape of the forging permitting this to be done, such grinding entirely disregarding the requirement for said half-moon, which protuberance on the inner surface of a bladeserves the same purpose as the resilientinsert 9. In other words, the inner surface of the twisted blade is ground to obtain a cutting edge and no special pr'otuberan'ces must be ground therein.

This concept ofgrinding the blade without any socalled half moon provides the solution of the grinding step of the blade without hand grinding, and enables the blade to be ground in a mass production system, from tip to the bow. J w V A Instead of grinding "one blade, a plurality of blades may be placed in a rack, and such plurality of blades ground together.

. The first and simplest shape of theback of the blade is a single curvature flat convex one. To prevent the rear edge from cutting materials, such edge is usually dulled. Other shapes may be used as heretofore described and shown, and in all cases it will be noted that such shapes have sides continuous from tip to bow, unimpeded by any obstructions, or protuberances, etc., as usual in the known scissors, to enable the mechanical automatic operations to be carried out, no protuberant or decorative portions being permitted as are common in the hand ground blades. All forms shown in the drawings have this continuity of substantially planular surface, from tip to bow, e'nabling'the operations to be carried out in one continuous step, from tipfto bow of the blade.

it will be noted that edge grinding and back glazing in "each case extending from tip to bow, extends beyond the pivot hole to the bow, which pivot hole may be placed nearer to the bow than heretofore and a longer effective cutting edge is thereby obtained.

it goes withoitt saying that the various cross-sectional shapes of a blade, are predetermined before the forging of the blade in contemplation of being used for the tip to bow hardening or grinding or glazing or polishing. 7

Of course, after said operations are applied to any of the blade surfaces, the blades may be polished, or plated, or otherwise treated to provide a commercially salable product, and such polishing proceeds along an unimpeded surface from tip to bow.

The resilient insert 9 is well known in the art and therefore by itself forms no part of my invention. It is preferred in the novel scissors over the conventional protuberances on the inner surfaces of scissors blades because such blades may then be treated in a continuous operation from tip to bow, as described.

It is, of course, elementary that better grades of scissors be provided witha twisted blade andthe resilient insert, but these essentials are used with and are part of the environment of the present invention which resides in the unique shape of; scissors blades permitting the grinding, glazing aitdpolishing of the blade surfaces in acontinuous operation from tip to bow, the shapeof the blades being such that the said continuous stepsmay be carried out.

The scissorsof this invention having blades whose sur faces may beground, glazed and polished in a single step from the tip to the bow may be produced at much less expense than thehahdground scissors with twisted blades ahd the so-called half-moon. v

I. wish it to be understood that l-do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in-the art.

Whatlclaim is:

In "a scissor, the ombination of two twisted blades with a finger eye at one end of each of said blades and "a tip'at the otherend of each of said blades, each of, said ade Pa in its smetandpvt sur a s. unimpededafid contiiiuousfrdmthe tip to the fin er-e e thereof, the linear dimensions of the cross-sections of said blades varying at a given ratio from the tips to the finger eyes of said blades, connecting means pivc-tally supporting said blades at a point closer to said finger eyes than to said tips, and spring means between said blades, one end of said spring 5 means being supported by said connecting means for axial movement between said blades, and the other end of said spring means being fixedly supported in one of said blades.

References Cited in the file of this patent UNITED STATES PATENTS Zylka Feb. 8, 1921 Whittemore Apr. 22, 1873 15

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