US1891029A - Self-adjusting trimming attachment for sewing machines - Google Patents

Description

Dec. 13, 1932. J. N STEIN 1,891,029

' SELF ADJUSTING TRIMMING ATTACHMENT FOR SEWING MACHINES Filed Sept. 17, 1951 l nvenTor. 3 33 Joseph NSTein bydflm [M @LMM Patented Dec. 13, 1932 UNITED- STATES JOSEPH N. STEIN, 0F DORCHESTER, MASSACHUSETTS SELF-ADJUSTING TRIMMING ATTACHMENT FOR SEWING MACHINES Application filed September 17, 1931. Serial No. 563,258.

This invention relates-to sewing machine attachments and more partlcularly to devices for trimming surplus material from the edge of the work being sewed.

When performing a trimming operation upon a sewing machine simultaneously with the formation of a seam, it is essential that the trimming mechanism function smoothly and accurately in conjunction with the stitch-forming mechanism. In performing a trimming operation on certain parts of a shoe upper such, for instance, as the uppermost edge where the lining is sewed to the top edge of the upper, the seam must be made very close to the edge. To accomplish a neat trimming operation in such case the mechanism must be maintained in accurate adjustment. A. further necessity for maintaining accurate adjustment of the parts is due to the fact that the needle moves in close proximity to the cutting edge of the trimming device. If one or more ofthe elements should become loosened or should sustain suiiicient wear to cause maladjustment, a great deal of damage and much loss of time may result. It is the general object of the presentinvention to provide a trimming mechanism fora sewing machine, the cutting edge of which will be maintained automatically in adjusting position with relation to the path of the needle.

A further object of the invention is to'provide a trimming mechanism in which the cutting blade is maintained resiliently in contact with a shoulder upon a rigidly fixed needle plate secured to the work support.

A further object of the invention is to provide a trimming device. the cutting edge of which will assume automatically its proper position after it has been reground or after the shape of the blade has been modified by any other agency, such as that of the natural wear caused by continuous operation of the machine. i

Other objects and features will more fully appear from the following description in connection with the accompanyingdrawing, and will be pointed out particularly in the claims.

In the drawing:

Fig. 1 is a planview oi the end portion of upper of a shoe.

mounted a casing 2.

the work supporting arm of a sewing ma chine showing the trimming mechanism. 7

Flg. 2 IS a fIOIlt'QleVittlOIl of the parts shown in Fig. 1 illustrating the work, the

needle plate and a portion of the work support in cross section. I

Fig. 3 is a detail perspective view of the cutting blade showing its relation to the work. i

Fig. 4 is a cross section on line 4:'4: Fig. 1.

The invention may be applied readily to sewing machines in general. As one example of a machine to which the invention is particularly adaptable, a shoe stitching machine will be described and'illustrated herein. The

machine illustrated is designed for performing certain stitching operations upon the i One of such operations is that of forming the seam-at the upper edge of the shoe upper which unites the upper and the lining. The present invention provides the means for trimming the surplus lining material during the formation of such a seam. Only those parts of the machine will be illustrated which are related directly to the invention. The remaining elements of the machine are or may be'of standard design well known to those skilled in the art. The trimmingmechanism is mounted desirably upon a frame or work supporting arm 1 ofa sewing machine upon the edge of which is adapted to receive the usual shuttle mechanism which cooperates with the needle to form the stitch. At the upper portion of the casing 2 ofa work supporting plate3 is secured by means of thescrews 4. The outer end of the plate 3 is recessed to receive a needle plate 5 which is secured in position by means of the screws 6. The needle plate is provided with an-aperture 7 through which the needle 8 passes during its vertical reciprocation. The needle plate 5 iscut away at itsouter edge to form a slot 9 in which a feed dog 10 is received which is actuated by the usual mechanism not shown herein. Situated above the feed dog is a rotary presser foot 11 which cooperates with the feed dog to feed the work 12 through the machine. a j i The trimming mechanism is mounted upon a flat plate or boss disposed in a horizontal position at the top of the work supporting arm 1. This flat plate may be integral with or detachably secured to the arm 1. The trimming cutter is composed of a shank portion 13 and a cutting blade 14 which are mounted to oscillate in a horizontal plane. Any suitable means may be provided to pivot the cutter. As shown herein the cutter is provided with a disk 16 secured to the shank 13 and extending downwardly into a circular recess 17 in a bearing plate 18.

The lower face 19 of the shank 13 rides upon the upper face of the bearing plate 18. The disk 16 secured to the cutter is retained in the recess 17 by means of the plates 20 secured to the upper face of the plate 18 and overlapping the upper face of the disk 16 which is flush with the upper face of the plate 18. The cutter is thus confined to a definite horizontal path and receives its oscillations from a driven element on the machine. The driving elementmay be a cam situatedwithin the arm 1 but not shown in the drawings which actuates a follower 21 depending downwardly from the shank 13 and extend ing through an aperture 22 in the arm 1.

The shank 13 is composed of two elements, the upper element 23 of which is pivoted upon a stud 24 secured in the lower portion 25 of the shank. The stud 24 desirably is fixed at the aXis about which the cutter oscillates. The upper member 23 overlies the lower member and is extended beyond the lower member of the shank at the end remote from the stitching point to form a. handle 26. This remote end of the member 23 is resilient and is provided with a slot 27. A pin 28 is secured in the lower portion of the shank 25 and normally extends into the slot 27 thus locking the upper portion 23 and the lower portion 25 against relative movement. WVhen the work 12 is inserted in the machine, it is desirable that the knife 14 be swung out of itsoperating position into the dotted line pos1t1on shown in Fig. 1. This is accomplished by raising the resilient portion of the member 23 by means of the handle 26 until the pin 28 clears the slot. The member 23 may then be swung about its pivot point upon tne stud 24. When the workis in position the cutter is then swung back to its full line position with the pin extending into the slot 27.

The knife 14 is carried theupper menrher 23 of the shank 13 in a novelmanner. The end of the knife extending toward the axis of the cutter is provided with slots 29 extending longitudinally thereof a d within which are received he screws 30. The screws 30 are secured rigidly to the upper meml'er 23 of the shank 13 by means of screw-thread ed end portions. The screws30 are provided with cylindr cal portions 31 which accurately fit the slots 29 and permit the knife 14 to move longitudinally toward and from the axis of the cutter. The heads of the screws 30 engage the upper face of the knife 14 acting to retain the knife in its proper horizontal plane. Any other suitable means may be provided for guiding the knife 14 relatively to the member 23. The knife 1 1 is provided at its outer end with a downwardly extending vertical portion 32. The forward edge of the portion 32 is sharpened to present a cutting edge. The cutting edge is inclined desirably rearwardly from its lower extremity upward- 1y. In forming the inclined cutting edge 33 a portion of the downwardly extending section of the knife 32 is cut away which results in forming a V-shaped recess with the edge 3t of the horizontal portion of the knife.

The knife 14 is forced outwardly away from the axis of the cutter by any suitable spring means such, for instance, as the expansion spring 35 which is anchored at one end to the stud 24- and is secured at its other end in an aperture 36 in the blade 14.. The plate 18 is secured to the flat plate or boss upon the work supporting arm 1 by means of a plurality of screws 37 in such position that the vertical end portion 32 of the blade 14 will bear with resilient pressure against a vertical face 38 upon the needle plate 5. The outer face of the portion 32 of the knife s formed desirably substantially cylinclrically with respect to the axis of the cutter thereby permitting the knife to move smoothly across the face 38 of the needle plate as the cutter oscillates. The upper portion of the cutting edge 33 is positioned to engage the work as it is fed across the needle plate.

To illustrate the operation of the device a composite portion of a shoe upper will be taken as an example of the work done by the machine. The work 12 is composed of an outer layer 39 and an inner layer or lining 40 which. are placed between the feed doc; 10 and the presser foot 11 with the edge of the outer member 39 bearing against the outer face of the depending portion 32 of the knife. The lining 40 which is invariably out only roughly to its final shape will project beyond the edge of the outer portion 39 and into the path of the cutting edge 33. The machine then is started and as the stitching progresses the kn fe 14 is oscillated at high speed and trims the uneven edge of the lining 4O flush with the edge of the outer member 39.

The distance between the cutting point of the trimming mechanism and the path of the needle will always remain unchanged since the spring 35 acts continuously to force the face of the depending portion 32 of the knife against the face 38 of the needle p ate 5. If the knife is removed for sharpening and a slight portion of the blade is removed. the spring 35 will act automatically when the blade is replaced in position to restore the cuttine edge to its original position. If the cutter becomes worn throughout a long period of operation, it will be forced automatically against the face 38 by the spring 35, thereby maintaining the accurate position of the cutting edge. Furthermore, since the needle plate is fixed rigidly in position and of itself positively maintains the cutter in a given position, the needle point cannot be broken by misalignment with the aperture through which it operates, nor can it accidentally engage the cutter. The invention, therefore, provides a highly efficient cutting means which may be maintained indefinitely in perfect running order with a minimum of expense and loss of time.

Having thus described the invention, what is claimed as new, and desired to be secured by Letters Patent, is:

1. A sewing machine attachment for trimming work during the stitching operation comprising a power driven pivoted cutter having a shank, a knife blade slidably mounted thereon and movable toward and from the pivot point, a work support, a needle plate fixed thereto presenting a vertical stop shoulder, a vertical face upon the end of said knife and resilient means acting to maintain the vertical face of said knife blade in engagement with said stop shoulder.

2. A sewing machine attachment for trimming the work during the stitching operation comprising a power driven cutter pivot-ally mounted to oscillate in a substantially horizontal plane and having a shank, a knife blade carried upon said shank and relatively movable toward and from the pivot point having a downwardly extending vertical end portion, a cutting edge flush with the outer face of said vertical endportion, a work support, a needle plate secured thereto presenting a vertical stop shoulder and spring means acting to maintain the end portion of tihe blade in engagement with said stop shoul- In testimony whereof, I have signed my name to this specification.

JOSEPH N. STEIN.

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