US3756174A

US3756174A - Device for sewing machines for cutting the edging of sewed materials

Info

Publication number: US3756174A
Application number: US00194649A
Authority: US
Inventors: H Wenz; F Schwarztrauber
Original assignee: PFAFF GmbH
Current assignee: PFAFF GmbH
Priority date: 1970-11-05
Filing date: 1971-11-01
Publication date: 1973-09-04
Anticipated expiration: 1990-09-04
Also published as: GB1346666A; IT939947B

Abstract

The disclosure relates to an improved cutting device for a sewing machine, the cutting device being of the type which is oscillated to cut a strip of material adjacent the seam as the material is being sewed to another material. Manually operated means is provided for rotating the cutting means against the feed direction of the materials being sewed so that the excess material can be separated when a sewing operation is complete. The device is constructed so that oscillation of the cutting device continues during the latter operation, called discharge cutting.

Description

Unite States atent Wenz et al.

Sept. 4, 1973 DEVICE FOR SEWING MACHINES FOR CUTTING THE EDGING OF SEWED MATERIALS Inventors: Herbert Wenz; Fritz Schwarztrauber, both of Kaiserslautern, Germany Pfaff Industriemaschinen GmbH, Kaiserslautern/Pfalz, Germany Filed: Nov. 1, 1971 Appl. No.: 194,649

Assignee:

Foreign Application Priority Data Nov. 5, 1970 Germany G 70 40 909.5

US. Cl. 112/127, 112/129 Int. Cl D051: 37/02 Field of Search 112/130, 122, 123,

[56] References Cited UNITED STATES PATENTS 2,925,794 2/1960 Mayeran 112/122 Primary Examiner-11. Hampton Hunter Attorney-0rville N. Greene and Frank Lowell Durr [57] ABSTRACT The disclosure relates to an improved cutting device for a sewing machine, the cutting device being of the type which is oscillated to cut a strip of material adjacent the seam as the material is being sewed to another material. Manually operated means is provided for rotating the cutting means against the feed direction of the materials being sewed so that the excess material can be separated when a sewing operation is complete. The device is constructed so that oscillation of the cutting device continues during the latter operation, called discharge cutting.

2 Claims, 3 Drawing; Figures g 4 i i 5 PATENTED SEP 4197.! 3 74 am: 1 0F 2 4 f X8 Fig.7 13 12 The invention concerns a mechanism for a sewing machine for cutting the edges of sewed material in which the blade of the cutter is oscillated by means of an oscillating lever, driven independently of the movement of the sewing mechanism and which can be shiftedfrom its normal operating position against the feed direction of the material to be sewed to completely cut off the excess material.

For the cutting of lining materials such as shoe stock, cutting devices are known which are equipped with an oscillating driven knife with a knife edge in a vertical plane and a horizontal protective flange above the blade angled away from the blade. A lining is thus cut close to the stitch line. There, the lining frequently projects also opposite to the feed direction of the goods to be sewed somewhat beyond the upper material, whereupon in the case where the seam ends at the edge of the upper material, the lining is cut only up to this edge of said upper material.

In order that this overhanging or extending lining strip does not have to be cut manually with a scissors by the operator, a cutting mechanism has already been developed by which the cutting knife is disengaged from its oscillating drive and allowed to be swung by means of a hand lever, so that the knife blade is drawn forward against the feed direction of the sewed material to thereby cut-off or separate the excess strip of material (which has already been partially cut parallel to the stitching) in a so-called discharge cut. This application of the cutting knife requires moving of the hand lever and the expenditure of comparatively large energy. This energy is greater, the thicker and more resistant is the lining material.

In order to reduce energy required to accomplish the discharge cutting, this invention provides for imparting the oscillating movements to the cutter blade during the discharge cutting to assist said cutting. The objects of the invention are attained by supporting an oscillating lever on a fulcrum axle which, in turn, is supported by a bracket for displacement of the fulcrumed axle to thereby vary the range through which the cutting blade oscillates the bracket, at least adjacent the fulcrumed axle, being movable in a plane which is parallel to the plane of the oscillating lever and is substantially vertical to a straight line, which passes through the point connecting the oscillating lever with the driving means and the point from which it is driven.

Through the resulting displacement of the oscillating range of the knife blade toward the feed direction of the to-be-sewed material in front of the stitch structure site, the edge band of the lining will accordingly be cut off during the discharge cutting, in the same way as during the main cutting process. The work discharge by discharge cutting is distinguished from the main cutting essentially only in that the relative movement between the lining material and the oscillating driven knife edge is accomplished in the first case through the feeding movement of the cutting blade, and in the second case through the feeding movement of the sewed material. The manually operated feed movement of the cutting action, which is overlapped by the mechanically produced oscillating movements, accordingly will be put into effect by the oerator only during a part of the cutting operation. Accordingly, the cutting apparatus of the invention requires the operator to expand less energy in the discharge cutting than the known cutting devices.

The inventive proposal is also applicable to cutting devices in which the cutting knife is not driven directly by the oscillating lever, but indirectly through an interposed auxillary member.

Further features and advantages of the invention will be apparent from the reading of the subjoined specification and from a consideration of the accompanying drawings.

IN THE DRAWINGS FIG. 1 is a side elevation of a support column of a sewing machine containing the cutting device of the invention shown in its normal cutting position.

FIG. 2 is a partly cut away front view of the disconnecting mechanism of the cutting device.

FIG. 3 is a plan view of the goods-support column of the sewing machine, with unimportant parts omitted, the solid lines showing the position of the cutting knife in normal cutting position, and the dot-dash lines showing the position at the end of the discharge cutting.

On the base plate 1 of the housing 2, the supporting column 3 is fastened. It carries the advancing rod VR for forwarding the sewed goods in the direction N. At the side of column 3, a bearing plate 4 is arranged for the reception of the cutting mechanism.

In the bearing plate 4,.a vertical, oscillating axle 5 is arranged, on whose upper end a supporting link 6 is clamped. On the supporting link 6, a vertical side arm 7 of an angled cutter-carrier 8 is adjustably arranged, the other side arm 9 extending at the upper part of the surface of the supporting column 3. On the arm 9 is fastened the extendible cutting knife 11 which is essentially balanced with respect to the needle hole 10 and which is adjustable in the direction of the hole 10. On the free end of the cutting knife 11, a right angled downwardly directed curved lip 12 is provided, whose radius of curvature essentially corresponds to the distance between the lip 12 and the oscillating axis of oscillating axle 5. The lip 12 is sharpened on its forward side to an edge 13, which is adjusted to slope downward in the cutting direction and is normally cutting close beside the hole 10. That balancing part of the knife blade 11, in the range of the edge 13, satisfies, in this explanatory example, the function of an improved safety flange, which serves in addition to keep the edge 13 from cutting the upper material.

The cutting blade 1 l is driven from a separate motor, not shown, which is positioned under base plate 1 imparts about 2,800 revolutions per minute to axle 14. The eccentric 15 is fastened on axle 14 and is encircled by eccentric rod 16. The other end! of rod 16 is adjustably connected the lower end 17 of rocking lever 18, which is joumaled for oscillation in bracket 19 through bolt or fulcrum axle 20. The essentially plate-form bracket 19 is pivotally mounted in housing 2 by stationary bolt 21 and has a laterally projecting arm 22, provided with a hole 23, which serves for the connection of the bracket 17 to a foot, knee, or hand lever (not shown) by means of a connecting rod (not shown). A tension spring 24, having one end connected to housing 2 and one end connected to arm 22, holds thebracket 19 in its normal position, said bracket also being held by means of the stationary bolt 25 which engages through the slotted opening 26 thereof.

On the upper end 27 of the two-arm oscillating lever 18, another lever 28 is arranged, which is joined to the driving element 29 for the lower end of the freely rotatable oscillating axle 5. The driving element 29 carries on bolt 31, a rotatable pawl 32 which by means of compression spring 33 is held in its upper position as shown in FIG. 2. Pawl 32, in its upper position, fits into slot 34 of dog 35, which is fixed to axle 5, so that oscillation of pawl 32 oscillates axle 5. The pawl 32 can be removed from slot 34 by pressing handle 40 downwardly against the action of spring 39 and so as to press the tripping pin 42, against the action of spring 43, to rotate pawl 32 in a clockwise direction.

Above the shift lever 37, a guide ring 44 is fastened on the axle 5 on which is provided a projecting fitted pin 45. On the shift lever 37 is fastened the vertical stop pin 46 to limit the swivel range of the pin 45. Between the shift lever 37 and the guide ring 44, there is provided, on the axle 5, a torsion spring 47, one end of which is fastened in the shift lever and the other end in the guide ring 44.

The apparatus of the invention operates as follows:

The oscillation drive of eccentric is transmitted over rod 16, rocking lever 18, and guide rod 28 to the drive element 29. From there, the drive movement continues over the pawl 32, the dog 35 to the oscillating axle 5, so that axle 5 oscillates around its longitudinal axis and oscillatingly drives the cutting knife 11. The oscillating swing of cutting edge 13 is adjustable through a distance of between 2 and 3.5 mm by shifting of the pivot point of eccentric rod 16 in the slot provided in the lower end 17 of lever 18. The cutting knife 11 cuts during the sewing process close to the stitch forming part of the lining on shoe stock, respectively, generally the lower of two superposed layers of material. The cutting thrust is thereby successfully executed with the seam formation on the advancing movement of the sewed material.

Frequently, the lining material extends beyond the edge of the upper material and for this case, the seam will end at this edge of the upper material with the lining cut only up to this edge. Thus the stitched side of the seam of the cut lining-band is still connected to the sewed material through the edge uncut portion of the lining material. For the complete cutting off of the lining band, while the sewing machine is at rest but while the knife 11 is still being oscillated as before, bracket 19 is swung in a clock-wise direction about bolt 21 by means of a foot, knee, or hand lever (not shown), connected to hole 23, for example. Simultaneously therewith, the swing lever 18 is likewise swung in a clockwise direction around the pivot point on the eccentric rod 16 and as a result thereof, the swing axis 30 (FIG. 2) of sewing lever 18 (determined by bolt and the guide rod 28 shifts correspondingly to the right with respect to FIG. 1.

The drive 29, arranged between rod 28 and the axle 5, has the function of a crank arm. Thence the shifting of rod 28 leads to a rotation of drive 29 and the axle 5 and consequently to a swivelling with the swing axle 5 of the connected cutting knife 11. As shown in FIG. 3, the rotation of axle 5 results respectively, in the swivelling of cutting knife 11 in the counter-clockwise direction with respect to the plan view, whereby the edge 13 moves essentially counter to the feed direction N of sewed goods. Concerning the safety, to be able to cut wide overlying lining strip, the long slotted hole 26 in bracket 19 is constructed large enough so that the blade 13 is shiftable up to about l5 mm. ahead of the stitch tap hole 10. According to the invention, the cutting apparatus is driven independently of the sewing device, also the cutting knife 11 is oscillated during the swinging process so that the oscillating movement is superimposed on the swinging movement. Thus, when bracket 19 is swung in the clockwise direction, the knife 13 will also be shifted essentially against the feed direction N of the sewing goods and thereby will completely cut the hanging lining tape on the end of the sewing material in so-called discharge cut. The higher the oscillating frequency and the greater the swing breadth or distance is, so much the greater is the share of cutting energy that the oscillating movement contributes to the total energy required for the cutting operation.

As soon as the finished lining tape is cut off, the operator releases the foot, knee, or hand lever, whereupon the tension spring 24 of support 19 draws the support back to the starting position after which the knife blade 11 and the oscillating drive therefor are in the normal position.

To now remove the blade 11 from the normal working position and into a rest position, the handle will be tilted downwardly against the action of spring 39. Thereby it presses on the tripping pin 42, whereupon this turns the pawl 32 in the clockwise direction. As soon as the projecting part of pawl 32 is withdrawn from the slot 34 of the dog 35, the drive connection on the oscillating axle 5 is interrupted. Simultaneously the torsion spring 36 is able to rotate the swing axle 5 in a clockwise direction until the pin strikes the stop pin 46. By this movement of the swing axle 5, the knife 13 is moved in the feed direction N of the sewing goods to a rest or inoperative position behind the normal working position and out to a rest position laterally behind the supporting column 3.

For then engaging the cutting apparatus, the handle 40 is turned backwards against the force of the torsion spring 47. Thereby the stop pin 46 rotates the pin 45 and the guide ring 44 of swing axle 5 back to the starting position so that the pawl 32 again engages the slit 34 of the dog 35 through force of the spring 33 and in this way the drive connection between eccentric l5 and the oscillating axle 5 is again operative. The support for the bolt carrying the oscillating lever on a housing bracket of the sewing machine is provided with displacement means to shift the oscillating axle of the es cillating lever and thereby the oscillating range of the cutting knife. The support therefore being movable in a plane parallel to the plane of the oscillating lever and vertical to a straight line, which passes through the connecting point between the oscillating lever and the eccentric rod and the fastening place of the cutting knife on this oscillating lever.

We claim:

1. An apparatus for sewing machines for cutting the edges of sewed goods with an oscillating cutting blade comprising a pivotally mounted vertical shaft for normally holding and oscillating said blade in the region of the needle-hole,

drive means for oscillating said vertical shaft comprising eccentric means driven independently of the sewing means connected to one leg of a lever with two legs fulcrumed on a shaft,

the excess side material from the sewed material. 2. An apparatus as claimed in claim 1, comprising manual means to release the connection between said oscillating lever and said vertical oscillating shaft, spring means on said vertical oscillating shaft which upon release of said connection swings said shaft and the cutting blade in the feed direction of the material to be sewed to a rest position away from the needlehole.

Claims

1. An apparatus for sewing machines for cutting the edges of sewed goods with an oscillating cutting blade comprising a pivotally mounted vertical shaft for normally holding and oscillating said blade in the region of the needle-hole, drive means for oscillating said vertical shaft comprising eccentric means driven independently of the sewing means connected to one leg of a lever with two legs fulcrumed on a shaft, a pivotable bracket carrying said shaft for the lever with two legs, means releasably connecting the other leg of said lever to said pivotally mounted vertical shaft, spring means normally holding said pivotable bracket in such a position that the blade is oscillated in the region of the needle-hole, said bracket comprising means for manually pivoting the same so that the blade, while still oscillating, shifts in a direction toward the feed direction of the material being sewed, whereby to completely cut the excess side material from the sewed material.

2. An apparatus as claimed in claim 1, comprising manual means to release the connection between said oscillating lever and said vertical oscillating shaft, spring means on said vertical oscillating shaft which upon release of said connection swings said shaft and the cutting blade in the feed direction of the material to be sewed to a rest position away from the needle-hole.