US3369509A - Cutting mechanism for sewing machines - Google Patents

Description

Feb. 20, 1968 P. E. BURTON CUTTING MECHANISM FOR SEWING MACHINES Filed Jan. 5, 1966 INVENTO/Q Arrow 5y ite States Patet Gfiice 3,369,599 Patented Feb. 20, 1968 3,369,509 CUTTING MECHANISM FOR SEWING MACHINES Perry E. Burton, Duluth, Ga, assignor to Sunbrand Corporation, Chamblee, Ga., a corporation of Georgia Filed Jan. 3, 1966, Ser. No. 518,164 8 Claims. (Cl. 112129) This invention relates to cutting mechanisms, and more particularly, to an improved cutting mechanism for use with a sewing machine for cutting thread chains, braid, belting, or the like passing through the sewing machine.

Prior art cutting mechanism of this general type have normally been operated with a scissor-like action, as suggested by US. Patent No. 1,286,113, issued Nov. 26, 1918 to A. S. Robinson, or with a guillotine cut-off mechanism such as that illustrated in Patent No. 3,146,742 issued Sept. 1, 1964 to H. R. George et al. While these prior art devices have been known and widely used commercially, they have not been entirely satisfactory due, in part, to the relative complexity of the known devices, and to the maintenance necessary to keep the shearing blades properly adjusted and sharpened. Accordingly, the primary object of the present invention is to provide an improved cutting mechanism, hereinafter referred to as a chopper, for use with a sewing machine, and which employs the chopping action of a blade striking an anvil to affect the cutting operation.

Another object is to provide an air actuated chopper for use with existing sewing machines and which may be mounted on the sewing machine table so that extensive modification of the machine is unnecessary. Another object is to provide an air actuated chopping mechanism employing a torsion bar mounting to reduce operating stresses in the chopper.

Another object is to provide a fully suspended chopper which allows freedom of movement of material to the right and to the left of the cutting blade to the extent normally permitted by the sewing machine itself.

Another object is to provide an improved air cylinder for a chopper which cylinder includes an automatic valving system built into the cylinder itself, and resulting in tremendous impact of the cutting blade with the material being operated upon or processed at the time.

Another object is to provide over-all simplicity in such a device.

Another objpect is to provide ease of maintenance and serving a textile chopper.

These and other objects made clear during the further progress of this specification are accomplished by means of the instant invention, a full and complete understanding of which is facilitated by reference to the drawing herein, in which:

FIG. 1 is a view in perspective, fragmentary in part, showing the instant device mounted in operative position on a sewing machine;

FIG. 2 is a somewhat reduced end view of the structure of FIG. 1; and

FIG. 3 is a longitudinal sectional view of the air cylinder used to drive the knife blade herein against the striking plate in what might be described as a pinching or die action.

Referring now to the drawings, in which identical numerals are used to describe identical or similar elements throughout the various figures thereof, indicates a fiat wooden table into which is recessed a conventional sewing machine 11; arm 12, and sewing head 13 being integral parts of said device. A mounting base 14 is provided with mounting screw holes 15 and 16, into which are aifixed suitable screws to secure such firmly in place on the table 10. A cantilevered mounting 17 rises from one end of said base as at 18 and extends first upwardly, then laterally and slightly to the rear of base 14 to position cutting blade 19, its holding or mounting element 20, blade guard 21 and super charged air cylinder 22 for operative engagement of blade 19 with striker plate 23 mounted on 14 at the end thereof opposite end 18.

Plate 23 is formed of stainless steel, preferably Armco 17-4-P.H., which is known as a self-hardening or precipitation hardening metal, work hardening severely under stress such as that generated by the instant chopper blade, which is precision ground chrome tungsten steel, with its edge ground at a relatively steep angle in order to give it the necessary strength and resistance to chipping.

Said striker plate is originally used in an annealed state, resulting in a soft surface for the blade to strike, which facilitates perfect mating of the blade edge with the plate. However, after repeated blows the area being impacted by the blade hardens, extending the service life of the approximately one sixteenth of an inch thick plate by several hundred thousand cycles. This is a disadvantage in drawing and stamping operations, but highly desirable in the case of the instant operation.

Since the blows of the blade on the striker plate result in a rather high noise level, a padding of neoprene cork or the like 24 is positioned under the plate.

Blade holder 20 is machined at a taper for the purpose of making the bottom very narrow so as not to interfere with the cutting operation, and has a ledge 26 against which the top edge of the blade rests to take the strain of the cutting action away from the two small screws 27 which the holder is tapped to receive in securing the blade itself. Said holder is drilled and tapped to screw on the end of the air cylinder piston rod.

Said air cylinder 22 is of suitable bore and stroke, with its head machined to provide a chamber 28 of suflicient size to receive a resilient female sealing member having a central aperture 29 the desired size; said seal being held in place by a resilient gasket ring 30. The piston 31 from the cylinder is drilled and tapped precisely in its top center 31A with a suitable thread and a male sealing member or stud 32 afiixed thereto. The cylinder wall is drilled with a small hole 33 near its top edge between female seal member and piston 31 when such is in retracted position; and the lower end block of the cylinder is drilled with three small holes 34 to facilitate escape of air trapped below the piston on the down-stroke. The operation of the piston and related parts is as follows: High pressure air from a remote source such as a compressor or tank (not shown) is introduced through line 35 into an adjustable power control unit 36 having a pressure guage 37, adjustable by element 38, the air then passing into the cylinder through surge tube 39. At this point the male and female sealing members forming the pressure sensitive dump valve are held together in their sealing position by piston return spring 40. Air pressure builds up within chamber 28 to a point high enough to push the male sealing member from its seat against the pressure of spring 40. The pressure required to compress spring 40 by pressing against a relatively small area of the male seal is substantially greater than that required to compress the spring when the entire end area of piston 31 is subjected to pressure. Thus relatively high pressure is permitted to build up within chamber 28 and tube 39 before piston 31 begins to move. When the male seal 32 leaves the female seal 29, the high pressure air from chamber 28 is dumped onto the relative large end area of the already moving piston, causing it the accelerate rapidly. When the rapidly descending piston 31 and the pinching or chopping blade 19 are stopped against the surface of striking plate, or anvil 23, the impact is effective to cut or chop any textile or the like material positioned on the anvil.

A suitable manually operable control valve, which may be foot or knee operated, is provided to control the flow of pressurized air to cylinder 22.. The valve is operated as soon as piston 31 is driven downward to cut off the pressurized air to cylinder 22, thereby allowing the cylinder to exhaust through port 33 and valve 36, as the piston 31 is returned to its retracted position under the force of spring 40. As the male sealing member enters the female seal, approximately three sixteenth of an inch of the return stroke remains. Air trapped between the piston top and the female seal is compressed and escapes through the small hole 33 thereby allowing the piston to fully retract, after which it is ready for another cutting or severing operation.

Cantilevered mounting arm 17 is provided with a laterally extending brace 17A provided with a brace screw 17B and associated nuts 17C, which screw is extended upwardly in mounting to fit snugly against the underside of arm 12, which means that while there is no drilling of the machine at this point, what amounts to three-point suspension is now established in conjunction with screws passed through holes 15 and 16 and into table 10.

The importance of this becomes apparent when considered in conjunction with the fact that in order to obtain rigidity in the power ranges in which the instant chopper operates, it is necessary to disperse the forces generated, over several points. The power used if attached directly to the sewing machine head 13 would force the chopper directly away from its base. In order to avoid this, the tubular suspended mounting member 17 was bent slightly rearwardly and the brace screw 178 provided. In operation, when the power cylinder drives the cutting blade against the striker plate 23, the reaction force on the cylinder causes the brace and screw to contact the sewing machine underarm with greater force than normally. The longitudinal axis of cylinder 22 is inclined rcarwardly slightly, as seen in FIG. 2, so that the line of action of the reaction force passes rearwardly of the point of contact of screw 1713 with machine arm 12. This arrangement converts much of the force of the cutting impact into a twisting motion, allowing the tubular member to act as a torsion bar and absorb the greater portion of the force, the remainder being expended on the underarm of the sewing machine, and the two screws holding the flat base 14 to table it) with subsequent distribution.

Blade guard element 21 is constructed so as to be adjustable upwardly or downwardly to allow free adjustment or passage of the item to be cut, yet at the same time prevent accidental insertion of a finger or fingers beneath the cutting blade. Said guard is fabricated of high carbon steel, hardened to a point where it will break before bending and thereby preventing changes by a user, the guard serving as a blade guide also. It is contoured in such a manner that the two screws which hold on the blade are in constant contact with it during the downward stroke of air cylinder and blade. If the guard is removed or designed in any manner other than specified, the chopper will, not operate as a cutter because of radial movement of the blade because the cutting unit is mounted at an angle,.and such movement results in only one corner of the blade striking the cutting surface.

From the foregoing it is believed that the operation of the instant air chopper will be obvious; and further that it and particularly the very high impact air cylinder taught herein is adapted to many uses and applications additional to those specifically described herein.

While there has been shown and described in considerable detail herein one form of the instant device, it is apparent that no limitation is intended or implied thereby, but on the contrary, various modifications, additions,

4 deletions, reconstructions and the like may be resorted to without departing from the basic invention and appended claims, which are to be accorded a scopeand interpretation fairly in keeping with the contribution to the art.

I claim:

1. A cutting mechanism for use with a sewing machine having an overhanging arm comprising, a frame, means mounting said frame on a supporting surface, an anvil having a generally horizontal surface adjacent to the stitch forming mechanism of the sewing machine, a chopping blade mounted on said frame for reciprocal movement between a cutting position in engagement with said hori zontal surface, and a retracted position spaced above said surface, means for forcefully driving said blade from said retracted position into impact with said anvil at said cutting position to cut material positioned on said horizontal surface by a pinching action, said frame including a cantilevered arm extending generally longitudinally of and in olfset relation to said overhanging arm, means mounting said blade driving means on the free end of said cantilevered arm and means fixed to said cantilevered arm intermediate the ends thereof engaging said overhanging arm thereby producing a torsional stress on said cantilevered arm upon impact of said blade with said anvil.

2. The'cutting mechanism defined in claim 1 further including means resiliently urging said blade into retracted position.

3. The device of claim 1, in which the cantilevered arm is tubular in form and provided with a brace and brace screw for contacting the overhanging arm of the sewing machine, thereby setting up said torsion bar action when the cutter mechanism is operated.

4. The device of claim 1, in which means are provided to regulate the amount of air entering the cylinder at a given time and under given working conditions.

5. The device of claim 1, in which a shock absorbing element is provided beneath the anvil, thereby reducing both noise and vibration when said cutting mechanism is functioning.

6. The cutting mechanism in claim 1 wherein said means for driving said blade comprises a quick acting pneumatic cylinder mounted on said frame.

7. The device of claim 6, in which the pneumatic cylinder is provided with a male and a female sealing element, a spring holding the piston in normally retracted position until such time as such spring is overcome by air pressure causing the seals to unseat and drive the piston downwardly with tremendous impact of the pinching-cutting blade against the striker plate to sever an object posi' tioned thereon.

8. The device of claim 7, in which the pneumatic cylinder is vented both above and below its piston to facilitate discharge of surplus air both on the downward and upward movement of the piston while in operation.

References Cited UNITED STATES PATENTS 3,063,321 11/1962 Nicolay 112-129 XR 3,238,850 I 3/1966 Desmarchelier 91--394 3,250,237 5/1966 Myska 112252 3,260,167 7/1966 Pedersen et al. 91-396 3,320,926 5/1967 Dexter et al. 83-658 FOREIGN PATENTS 1,157,897 11/1963 Germany.

JORDAN FRANKLIN, Primary Examiner,

H. H. HUNTER, Examiner.

Claims (1)

1. A CUTTING MECHANISM FOR USE WITH A SEWING MACHINE HAVING AN OVERHANGING ARM COMPRISING, A FRAME, MEANS MOUNTING SAID FRAME ON A SUPPORTING SURFACE, AN ANVIL HAVING A GENERALLY HORIZONTAL SURFACE ADJACENT TO THE STITCH FORMING MECHANISM OF THE SEWING MACHINE, A CHOPPING BLADE MOUNTEED ON SAID FRAME FOR RECIPROCAL MOVEMENT BETWEEN A CUTTING POSITION IN ENGAGEMENT WITH SAID HORIZONTAL SURFACE AND A RETRACTED POSITION SPACED ABOVE SAID SURFACE, MEANS FOR FORCEFULLY DRIVING SAID BLADE FROM SAID RETRACTED POSITION INTO IMPACT WITH SAID ANVIL AT SAID CUTTING POSITION TO CUT MATERIAL POSITIONED ON SAID HORIZONTAL SURFACE BY A PINCHING ACTION, SAID FRAME INCLUDING A CANTILEVERED ARM EXTENDING GENERALLY LONGITUDINALLY OF

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