US2320784A - Seam ripper - Google Patents

Description

H. A. LIVINGSTON ETAL June l, 1943..

SEAM RIPPER Filed Jari. l, 1943 Snventors MA. L/wA/a-sraw,

(ttornegs.

GJC/wapo Patented June 1, 1943 SEAM RIPPERV Harold A. Livingston and Carlos J. Cardona, Hollywood, Calif.; said Cardona assignor tosaid Livingston Application January 1, 1943, Ser-iaLNo. 470,968.

(Cl. Ell-272) 21 Claims.

This invention relates toa seam ripper, that is to say, a device which is particularly adapted to the ripping of sewed seams, although itisnot necessarily restricted to such an operation, because the device -has great utility for many other cutting purposes.

Among the principal objects of the invention are those set forth below:

First. To perform a cutting operationlby means of al sharp bladethat is reciprocated longitudinally in the plane ofthe blade in such a manner that it becomes possible to keep substantiallythe entire cutting edge ofthe blade in contact with a substance or article to be cut.

Second. ToV cause the blade to swing freely in the plane thereof by eliminating any lateral `guide or other structural member likely to come in contactr with'the `moving blade;

Third. To so mount and suspend the bladethat its travel in the plane thereof is'extremely'flexible, but that at the'same time the deviation or deflection sidewise of its plane is rigidly prevented.

Fourth. To have the blade disposed for reciprocation electrically, whereby a high cutting speed results.

Fifth. To provide an instrument that consists of lfew parts, is simple in operationL and durable in construction.

Sixth. To provide an instrument in which the cutting member is indefinitely replaceable, that is to say, in which new cutting members are easily substituted'for old ones as soon as the latter lose the desired efficiency.

Seventh. To provide an instrument in which ordinary safety razor blades, especially those discarded after shaving, are advantageously utilized.

Other'objects too, will become evident after the invention is more fully understood.

Cutting instruments of the class to which the invention belongs, are usually of a construction in which'two blades are connected mutuallyV together scissor-fashion, and while such instruments can and are operated electrically, still in each oscillation of the scissor blades, the extent of :the cutting action yis limited to rather short, cooperative oscillations of the blades.

In the device of the invention, on'the contrary, the entire cutting edge of the singlev blade is in contact, at one and the same time, with the article tobe cut;wheresuch article is at least vas long as the blade. Therefore, insteadof being limited to only-the actual -length of `the stroke inthe cuttingoperation, the'effective lcuttingresult in each Stroke is Virtually'equal to-'the number Aof* times In the accompanyingdrawingy` which illustrates' one embodiment of the-invention, Y

Fig. 1 representsa front elevation, lpartlyv in section, taken on theline l-I Vlin Fig; v2.;

Fig. 2, a side elevation partlyin section, taken on the line 2-2 'in Fig.` 1;

Fig. 3, a fragmentary-portion of Fig. 2,' showing! an `alternate position of certain operativel parts;

Fig; 4, a 4side elevation of another embodiment of the invention, drawnlto' avreducedlscale;v

Fig. 5, a front elevation ofthe embodimentof Fig. 4; andi l f Fig..6, aV fragmentary vertical section Ataken through the handle portion Aof the embodiment of Fig. 4, showing the details of an electricaltrigger switch for starting and stopping the operation of the device. Y

Referring tothe drawing, the numeral la linw dicates ahousing-made of any suitable material, such-as a moldedplastic. Projecting upwardly from the housing Il) is` a `handle portion l2 which advantageously is y integralv with the housing. Withima'chamber orrecessf I4 tlfiatfisV enclosed by the housing, there is reciprocativelymounted a vibrating elementl lfhaving the movable arm |54-I and the iixed arm l5-'2, the latter'being held inplace against an abutmentv I1, by `any suitable fastening means, for example, screwsv I8. The-movable'arm IE-l is .cantilevered from the stationary arm Vl 5-2 by means of the Aelbow/portion Iii-3.v Advantageously, the vibrating elemen-t l5 is made-of extremely resilient materialI such as spring steel, which gives the elbow por tion a high'degree-of iiexibility', owingflargelyto its-crosssectional proportions. These propor tions are so chosen that thewidth ofth'ematerialy is considerably in excess of its thickness; and'lies substantiallyparallel to the `axis of oscillation, thereby imparting stability;

Rigidly attached 'tothe movable arm i5`| is an'armature |9,'made'for example; of 'soft iron and'having aA foot 19e-I integraltherewith. Th@

loot has depending from it a bracket l9-2 lying in a plane that extends at substantially right angles to the axis of oscillation of the resilient elbow portion l5-3. Removably attached to the bracket l9-2 is a cutting blade 20 having its lower or active cutting edge 2li- I extending somewhat below the lower edges lll-l of the housing I0. The blade 2U, in this instance, is advantageously an ordinary double-edge safety razor blade, but a blade of any other suitable kind can be used if desired. The blade is conveniently fastened to the bracket l9-2 by means of screws 2l, and the intervening washers 24, through it is obvious that there is nothing restrictive in this method of fastening. Energy for reciprocating the blade 2B is advantageously through an electromagnet comprising for example, a coil wound around a spool 26 and enclosing a core 21, the core being energized electrically, in this instance A. C., by means of the leadsZS-l forming part of an ordinary electric appliance cord 28. Obviously, the use of D. C. electricity can be provided for bymaking well known changesin some of the minor details herein shown and described.

When the coil 25 is energized, the electromagnetic force set up in the core 2l acts to intermittently attract the armature I9 counter to the potential mechanical energy Vstored in the spring means l5-3. lSince the A. C.V electric current varies in each cycle from zero to maximum and back again to Zero, the electromagnetic force in the core varies accordingly. Whenever, the electric current is at zero, the tension in the spring element l5-3 becomes eiective to return the armV l5-l, and consequently the armature I9 also, to their normal position, indicated in Fig. 2, allina manner that is well known.

Since the blade 20 is xed relative to the armature, it is obvious that any reciprocative motion, indicated by the double-pointed arrow 29 in Fig. 2, of the armature imparts to the blade `2l) corresponding reciprocative motion indicated by the double-pointed arrow 30. It is to be observed that the exact motion of the blade relative to the motion of the armature depends upon the angle existing .between the armature I9 and its foot IS-L In this instance, the angle is assumed to be as indicated at 3|, but of course, this angle can be varied to suit different requirements. 'Ihe motion at any particular point of the blade is represented by an arc described from the center of oscillation lying in proximity to the bend of the spring means. The motion of the cutting edge 2li-,I `of the blade is compound in character having both a vertical and a horizontal component. This results in a very effective draw-cut upon material to which the instrument is applied. The ratio between the vertical and horizontal components is determined vto a large extent by the magnitude of the angle 3l.

v The horizontal component causes the blade to be drawn back and forth in material to be cut, while the vertical component causes the blade to alternately sink into the material and to be lifted out again.

The two side walls I02 and lll- 3, Fig. 1, of the housing are advantageously curved inward so as to at least partially define the guard portions lli-4 on either side of the blade2i), thus facilitating the manipulation .of the device in following definite lines of cutting. Y Y

As a matter of convenience in assembling the operative parts of the mechanism, the end wall lll-fmay beseparablefrom the remainder of the housing along planes indicated by the lines Ill-5, and may be removably attached thereto by means of screws 32 or other fastening devices, these fastenings being placed wherever most convenient in any particular design of the device.

The spool 26 can be fastened to abutments 34, projecting inwardly from the housing, by means of screws 35.

If desired, a resilient cushion 3l, of rubber or other material, may be disposed in a suitable location for taking up the force of the spring impact of the arm I5-l.

Instead of providing an armature as a separate though rigidly attached part of the spring arm, the spring arm itself can constitute the armature. Such a construction is shown at 4D in Fig. 3. In that case, however, the armature would consist of spring steel and this might frequently be objectionable owing to the possibility of the armature freezing to the core of the electromagnet. Even so, a thin strip (not shown) of a non-magnetic substance, such as brass, can be attached to the face contacting the core. Since this is a common expedient, it is not here illustrated.

A feature in addition to maximum cutting-edge contact, that makes this device particularly suitable for seam ripping is the downwardly converging disposition of the eguards Ill-4 whereby it becomes possible to provide the sharply defined hold-down edges 4I closely adjacent the cutting edge on either side thereof. Each holddown edge is flanked by a side face 42 that slopes rather acutely upward and outward from the respective hold-down edge. Because of this construction, it becomes feasible yin operating the instrument of the invention, not only to accurately follow a seam but also to put the stitches of the seam in a condition favorablefor severing the thread as the instrument is moved along the seam.

The favorable -disposition just described, is visible in Fig. l,` where the numerals 43 and 43-I designate two portions of an article made for example of a textile fabric, the two respective portions having previously been sewn together by means of a thread at 45. In pressing down upon the instrument, after it is so placed that the blade 28 comes approximately into alignment with the seam, a small depression or channel is formed immediately underneath the cutting edge of .the blade. Obviously, this depressionorchannel follows the seam as the instrument is moved along the latter. The oppositely sloping faces 42 exert horizontal 'force ,components in opposite directions and tend to push the article portions apart from each other countering the holding power of the stitches. This of course, tends further to draw the thread in each stitch, taut, directly across the path of the blade when it descends', and so, puts the stitchesin advantageous condition for producing a satisfactorysevering effect. It is possible that .thespace as shown at 46 between .the portions 43. and 43-I, is somewhat exaggerated, but liso, itis done for the sake of clarity.`

The utility of the invention is not restricted to the ripping of seams, but extends to the exerting of an improved cutting effect upon Various substances, such as the constituents of most textile fabrics. This follows largely because the mutuallyV opposed, inclined, flanking faces 42 are effective to tense the surface 4structure of a textile or like material simultaneously with the occurrence ofthe rapidly repeated, blade-length, drawcut slashes orlstrok'es that are characteristically produced by the reciprocating blade. A

The method of mounting the blade is noteworthy in that it makes possible the novel isolation of the cutting edge from any environing structural parts. This isolation results. in great freedom of motion of the cutting edge, because neither the blade no r its exible mounting are in, rubbing or other friction-producing contact with any other structural part. Witness the contrary in scissor-like cutting devices where one blade is in close rubbing contact with another bl-ade.

In the present device, the solecontact or connection between the blade and any associated st ructural part is by means of a flexing `element located remote fromv the cutting edge. In this instance the exing element is represented by the 'spring elbow |5-3. Thus the cutting edge swings free of any inherent retarding influence thatmight otherwise be exerted upon it. c

In the rapidity of its performance in vany given cutting operation, the instrument of the invention with its blade-length incision in each cutting stroke, has a4 considerable advantage over a scissor-like device where each cutting stroke results in only a comparatively short bite.

The disposition of the center of oscillation of the armature in its relation to the cutting edge hereinbefore alluded to, makes possible various characteristic cutting results. This can be seen more particularly in Fig. 1, where it may be assumed the center of oscillation is located approximately at the point lll. Bydrawing theradii 41| to -414 through various points in the cutting edge 2li-l and constructingthe corresponding right triangles 48-l to 15S- 4, the motion f eects at the various points are graphicallyrepresented. The hypothenuse of each triangle virtually coincides with a short arc at the same point. By constructing the respective right triangles, the altitudes thereof represent vertical motion components, and the bases thereof, horizontal motion components,

In the triangle 43-1 the base is longer than the base in any of the others, while in triangle 48-4 the base -is shortest. The draw effect varies accordingly. Again, in triangle 48-I the altitude is lower than the altitude in any of the others, While in triangle 48-4 the altitude is highest. The incisive cutting effect varies accordingly. As a result, the cutting edge exercises -a real draw-cut action from end to end of the blade.

In Fig. 1 the angle 3| is greater than a right angle and the center of oscillation is located outside a perpendicular 5 0r erected at one end of the cutting edge. These conditions may represent one extreme. Another extreme would be where the angle at 3i is made a right angle, and the perpendicular in which .the center of oscillation would be located, is erected at th-e middle point of the cutting edge, as indicated at 5l. Fig. 1 serves to make plain the cutting results yat .the extremes mentioned, as well as at points intermediate `the extremes.

To aid in guiding the device along a seam, and in spreading the seam so that threads thereof will be taut in preparation for the cutting operation, it is preferred that a pilot be provided in advance of lthe blade. The pilot member 55, clearly illustrated in Figs. 2 and 3, is disposed centrally of the front face of the device, and diverges upwardly and backwardly from a nose 55a. It is preferably formed integral with the housing l0. The nose 55a preferably lies in alignment with the cutting edge of the blade, so

theypilot member will be most effective in the performance off its guidingv 'and spreading function.

Itu is a-dvantageous to provide a built-in electrical switch in close proximity to the handle of the device, so operation of the cutting Vblade may be easily and quickly controlled.

To Ithis end, as well as to facilitate manipulation off the device, the handle is desirably formed as a pistol-grip," and the control-switch actuator as a trigger. In the embodiment of Fig. 4, the pistol-grip 56 is of conventional formation, advantageously hollow, and is provided with protruding linger bearings 56a. The electric-alV cord 51, containingA the electrical lead wires 58 and 59, preferably enters the device through the free terminus of the pistol-grip 56, an insulatingV bushing 60 being tted therein for that purpose. Electrical termin-al pieces El andA 62 are secured within the hollow of the pistol-grip, conveniently by screws, as shown, certain of the screws serving also asA blinding means to attach the lead wires y58 'and' 59 to the respective terminal pieces, Spring-contact portions Gla and 62a, extending from the respective terminal pieces 6|` andl 62 into spaced, mutually adjacent positions, provide switch` elements, o-perable by means of the trigger 63. Thus, it can be seen that energization of the electro-magnet 64 may be easily and quickly controlled by the indexlinger of the hand which holds and guides the device.

Whereas this invention is here illustrated and described with respect to preferred specific embodiments thereof, it should be understood that various changes may be "made in :those specific embodiments andthat various other embodiments of the invention` may be constructed by those skilled in the art Without departing from the spirit andv generic scope ofthe invention as set forth herein and in the claims which here follow.

Having fully described our invention, what we claim is:

1.` A seam ripper, including in combination, a

free-swinging blade having a longitudinally extending cutting edge; and'electromagnetic means operative to impart a reciprocative draw-cut motion to the said blade along a line that is substantially in alignment with the longitudinal dimension of the said cutting edge.

2. A cutting device, including in combination, a blade having acutting edge; electromagnetic means operative to impart a draw-cut motion to the said blade whereby the blade is reciprocated lengthwise of the cutting edge; and a housing in vwhich the said blade and the said electromagnetic means are mounted, the said housing having mutually converging wall portions that at least partially define guards extending along the said cutting edge in close proximity thereto.

3. A cutting device, including in combination, a housing; an electromagnet mounted Within the housing; an armature suspension comprising an armature portion disposed along a magnetic face of the electromagnet; a foot extending from the armature portion substantially parallel to the axial plane of the electromagnet; a stationary arm; a spring member connecting the armature portion to the stationary arm; a blade depending from the said foot, the said blade having a cutting edge lying in a plane substantially parallel to the said axial plane; and means for energizing the said electromagnet.

4. A seam ripper, including in combination, an electromagnet; an armature operatively associated therewith; a blade mounting extending rigidly from the armature in the plane of oscillation thereof; and a blade xed on the said mounting, the said blade having a cutting edge' extending lengthwise thereof and disposed for reciprocation in strokes substantially in alignment with the lengthwise dimension of the said cutting edge.

5. A seam ripper, including in combination, a blade having a cutting edge, the said blade being structurally mounted t swing the cutting edge in a path wherealong the cutting edge is constantly free of any other structural member, the said path further, extending lengthwise of the cutting edge; and means operative to reciprocate the said blade along the said path.

6. A seam ripper, characterized by having a cutting edge that is isolated from an associated structural environment, including in combination, a blade of which the said cutting edge is a part; a resilient cantilever mounting disposed to oscillate in a plane and to rigidly carry the blade in the plane of oscillation; a structural environment for supporting the resilient mounting; and means operative to reciprocate the said resilient mounting.

7. A seam ripper according to claim 6, wherein the said resilient mounting has the center of oscillation so located that a draw-out motion is imparted to the said blade along the cutting edge thereof.

8. A seam ripper according to claim 6, wherein the said resilient mounting has a center of oscillation lying in a perpendicular erected between the extremities of the said cutting edge.

9. A seam ripper according to claim 6, wherein the said resilient mounting has a center of oscillation lying in a perpendicular erected at one extremity of the said cutting edge.

10.V A seam ripper, including in combination, an electromagnetic system having a Vibrating armature; a blade having a cutting edge fixed in relation t0 the said armature, the said cutting edge being disposed to define an included angle in conjunction with the plane of the armature, and further, the vertex of the said included angle being located within the limits of the oscillating system; and means operative to reciprocate the armature.

11. A seam ripper according to claim 10, wherein the said included angle is at least greater than a right angle.

12. A seam ripper according to claim 10, wherein guards having hold-down edges flanked by means disposed to tense the surface portions of a textile or similar material, are spaced apart from and disposed longitudinally on both sides of the said cutting edge.

13. A cutting device, including in combination, a reciprocable member having a cutting edge in substantial alignment with the line of reciprocation, guards spaced apart from and extending longitudinally along the cutting edge; means whereby the guards, when in contact with material having a yielding surface, tend mutually to tense such yielding surface during the reciprocation of the cutting edge; and means operative to impart motion to the reciprocable member.

14. A cutting device according to claim 13, wherein means are included to cause the motion imparted to the said reciprocable member to exercise a draw-cut effect upon the said material when the said cutting device is impressed thereon in the operative position.

l5. A cutting device, including in combination, a blade having a cutting edge extending along substantially a right line, means operative to restrict the motion of the blade to a path such that the cutting edge in al1 positions thereof is kept approximately in alignment with the said right line; guards disposed in spaced relation to the cutting edge on both sides thereof; and means operative to reciprocate the blade along its restricted path.

16. A cutting device according to claim 15, wherein the said guards have hold-down edges adjacent the cutting edge, and side faces flanking the hold-down edges, the said side faces being disposed to slope upwardly and away from the respective hold-down edges.

1'7. A cutting device according to claim 15, wherein the said blade is restricted to motion such that the cutting edge thereof follows a draw-cut path.

18. A cutting device according to claim 15, wherein a pilot is disposed in advance of said guards.

19. A cutting device according to claim 13, wherein a pilot is disposed in advance of the said blade, and has its nose lying substantially in line with the cutting edge of the blade.

20. A cutting device according to claim 13, wherein a pilot is disposed in advance of the said blade, and has its nose lying substantially in line with the cutting edge of the blade, the body of the pilot diverging upwardly and backwardly from the said nose.

21. A cutting device according to claim 2, wherein a pilot is disposed in advance of said guards.

HAROLD A. LIVINGSTON. CARLOS J. CARDONA.

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