US3034460A - Sewing machines - Google Patents

Description

y 1962 J. A. WENNSTROM 3,034,460

SEWING MACHINES Filed om. 20, 1960 I 4 Sheets-Sheet 1 Fig. 1 INVENTOR.

J0/m 14. Wennsfrom A TTORNEY May 15, 1962 J. A. WENNSTROM SEWING MACHINES 4 Sheets-Sheet 2 Filed Oct. 20, 1960 INVENTOR.

John A Wenn sfram ATTORNEY y 1 1962 J. A. WENNSTROM 3,034,460

SEWING MACHINES Filed Oct. 20, 1960 4 Sheets-Sheet 3 INVENTOR. John A. Wennsfrom 1w. TTORNfY United States Patent York Filed Get. 20, 1960, Ser. No. 63,787 Claims. (Cl. 112-123) Industrial sewing machines designed to perform a variety of sewing operations, such as overseaming, hemming and overedging, are generally equipped with a trimming cutter which trims the edge of the material immediately before the seam is formed. The trimming cutter commonly consists of a stationary lower cutter blade adjacent the needle plate and a movable upper cutter blade which is generally downwardly slanted towards the needle plate and is operated in timed relationship with the feeder.

I Economy requires that the width of the trimmed oil strip be held to a minimum.

Experience has shown that this requirement is difficult to meet in certain sewing operations and with certain materials.

In hemming knit goods, tricot, nylon materials and elastic materials which have a tendency to roll or curl, particular difi'iculties are encountered.

Three thicknesses of material pass under the presser foot in a hemming operation in which the material is folded in the shape of an S as viewed from the end, and in which the machine trims the top layer of the material and forms a seam between the trimmed edge and the fold therebelow.

Quality of workmanship demands that this seam is continuous. In the past, however, difficulties were experienced in crossing seams. The needle failed to catch the lower fold at, or immediately following, the crossed seams resulting in a faulty open hem at that point. Openings in the seam of the order of one-half inch were common and these openings assumed even larger dimensions when the garment was subsequently stretched. A difiiculty of a different character is encountered in certain sewing operations, for example hemming, of elastic material which has a tendency to roll or curl back into the seam. The danger of curling into the seam is lessened if an ample overlap is provided which is then trimmed off during the sewing operation and therefore represents waste.

The present invention overcomes both of the aforementioned difiiculties with the same mechanical equipment, the heart of which is a roller on the presser foot, movable up and down with the presser foot and extending into the area in front of the trimming cutters.

It has been proposed to fit the presser foot with a laterally extending finger. These attempts, however, proved unsuccessful, as the finger readily catches cross seams and frequently causes the material to ride up on the upper trimmer with resulting failure of the trimming operation.

Particulars of my improved construction, and the above as well as further objects, features and advantages of this invention will appear more fully from the detailed description which follows accompanied by drawings showing, for the purpose of illustration, an embodiment of this invention installed in an industrial sewing machine of otherwise known construction. The invention also resides in certain new and original features of construction and a combination of elements hereinafter set forth and claimed.

Although the characteristic features of the invention which are believed to be novel will be particularly pointed out in the claims appended hereto, the invention itself 3,fi34,460 Patented May 15, 1962 and the manner in which it may be carried out may be better understood by referring to the following description taken in connection with the accompanying drawings forming a part of it in which:

FIG. 1 is a perspective View of an industrial sewing machine in which my invention is incorporated, the machine being set up to perform a hemming operation on stretchable goods;

FIG. 2 shows the machine of FIG. 1 with its presser foot swung out of the way to expose the needle, the looper and the trimming mechanism;

FIG. 3 is a perspective view on an enlarged scale of the presser foot and surrounding elements after removal of the goods, the hem fold guide being swung up; and

FIG. 4 is a perspective view from above of the presser foot, the roller on the presser foot and a guide on the needle plate.

In the following description and in the claims various details will be identified by specific names for convenience. The names, however, are intended to be generic in their application. Corresponding reference characters refer to corresponding parts in the several figures of the drawings.

The drawings accompanying, and forming part of, this specification disclose specific details of the invention for the purpose of explanation of broader aspects, but it is understood that the details may be modified without departure from the principles of the invention and that the invention may be applied to other machines than the one shown.

Referring to FIGS. 1 and 2, the industrial sewing machine 11 is of generally known construction except for certain details hereinafter described and claimed at the end of the specification. The machine need not be described in great detail with respect to its general construction, particularly since a detailed description of a machine of this general type is found in the prior patent to R. A. Nering, 2,827,869, dated March 25, 1958.

Suflice it to say that the machine is driven by a belt which may be placed in the V-groove 12 of a hand wheel 13 on the end of a drive shaft which is not visible in the drawings.

The machine is set up to perform a hemming operation on knit goods which require a hem stitch permitting stretching of the material lengthwise of the hem. Two spools of thread 14 and 15 are visible from which threads 16 and 17 extend through tensioning assemblies 18 and 19 to the needle 2% and the looper 21, respectively. The needle 20 is curved and travels back and forth in the direction of its curvature and the looper 21 travels roughly in a direction towards, and away from, the observer of FIG. 1.

A presser foot arm 22 (see also FIG. 3) is pivotally mounted on the body of the machine at 23 so that it may be swung out of the Way as shown in FIG. 2. The presser foot arm is normally engaged by a spring urged plunger assembly 24 comprising a lever 25 for raising the plunger proper 26 out of engagement with the presser foot arm whenever it is desired to swing the presser foot out of the way. FIG. 2 shows the lever 25 in its raised position in which the plunger 26 is withdrawn. The presser foot arm 22 has a substantially horizontal pin 27 at its end resting in a surface depression of the presser foot 28 which may pivot about the pin 27 and is attached to the presser foot arm by means of a hinge spring plate 29 which is roughtly of the shape of the figure 6. The finger of the 6 bears down on the pin 27 from above and the hinge spring plate may be loosened or tightened by means of a screw 30 extending through the body of the 6 into the presser foot (see also FIG. 4).

The presser foot has an upwardly curved toe portion 31.

A hearing block 32 is mounted by a screw33 in a transverse recess 34 just forward of the hinge spring plate 29 and carries a roller 35 with freedom of rotation about a substantially horizontal axis. The roller 35 has a small diameter portion 36 adjacent the bearing block and a large diameter portion 37 remote from the bearing block. The large diameter portion is preferably tapered, as the drawings show, and lies just forward of the upper trimmer 38 which is a blade of substantially L-shaped cross section, disposed at a downward slant with its lower cutting end ground substantially vertical. The trimmer 38 is clamped to an upper cutter holder 39 which moves up and down and is provided with a holder clamp 44} and screw 41 by means of which the trimmer knife is tightened against the holder 39 proper. The corresponding lower trimmer is partially obscured in the drawings by other parts, but a portion may be seen at 42 in FIG. 4, as well as a portion of the screw 43 which secures it next to the needle plate 44.

As disclosed in detail in the above mentioned patent to Nering 2,827,869, one rotation of the main drive shaft carrying the hand wheel 13 causes the needle 20 to perform one stitch, the trimmer 38 to perform one cutting stroke, and the feed dog 49 to perform one feed stroke, all in timed relationship.

A stationary guide 45 secured by a mounting screw 46 is installed in advance of the roller and alongside the toe of the presser foot, as is best seen in FIGS. 3 and 4. The guide has a downwardly tapered trailing portion 47 which terminates just short of the roller and forms a nip with the roller, so that goods pass above the trailing portion of the guide and underneath the roller. The width of the trailing portion is less than the lateral extent of the roller beyond the side edge of the presser foot. For this purpose the guide is provided with a curved lateral portion 48, as best seen in FIG. 4. FIGS. 3 and 4 also show the teeth of the feed dog 49 adjacent to the stationary teeth 50 on the needle plate 44.

Referring particularly to FIG. 3 which illustrates the disposition of the roller 35 and of the stationary guide 45 with respect to the trimmer 38, it is readily seen that material passing through the nip between the roller and the guide is prevented from climbing up on the upper trimmer knife so that positive trimming action is insured.

Returning now to FIGS. 1 and 2, it is seen that the material 51 is first folded back upon itself, as visible in part at 52, whereupon the material is folded again at 53 so that three layers of material are formed. The bottom layer passes over the work plate (FIG. 3), whereas the upper two layers pass through a hem fold guide 55 so that the operator may gauge the width of the hem more conveniently. Viewing the hem from the front, that is from the operators end, the material is folded in the shape of an S and in such a way that the edge 56 of the material extends slightly beyond the first fold. The margin should be slight, of the order of one-quarter of an inch. If less, the production of a clean hem is somewhat uncertain, if more, the operation becomes wasteful because the margin must be trimmed oif by the trimmers.

If elastic material is being sewed, the margin tends to curl up and roll into the hem, as well as tending to ride up on the upper trimmer. For this reason, operators heretofore were tempted to work with an ample margin, sometimes as much as one-half inch, resulting in excessive waste of material. As shown in FIG. 1, however, the roller and stationary guide prevent an upward curl of material which is quite noticeable at 57 even though the material used in the illustration was not elastic material, but simply knit nylon.

After the hemming operation the material is flattened out along the first fold 52 and has then the appearance of the hem 58.

Turning to FIG. 2, the presser foot has a flat heel portion 59 rearward of the hinge 27, the heel portion being cut out at 60 to provide space through which the needle passes. The plate 61 on the side of the presser foot arm is a thread cutter plate (FIG. 3) which permits cutting of the thread 16, for example by pulling the thread forward into a sharp edged wedge shape cutout 62 in the plate.

Oviously the shape of the presser foot and other elements of the machine may be varied to suit the individual requirements of specific sewing jobs.

What is claimed is:

1. In a sewing machine, the combination of a lower feeder; a presser foot above the feeder; a lower stationary cutter alongside the feeder; an upper cutter in shearing association with the lower cutter; a roller; and means for mounting said roller on said presser foot for rotation about a substantially horizontal axis, the roller being in a position to extend laterally beyond the side edge of the presser foot and in front of the cutters so as to bear down On that portion of the material to be sewed which is trimmed off by the cutters.

2. In -a sewing machine, the combination of a lower feeder; a presser foot above the feeder; a lower stationary cutter alongside the feeder; an upper cutter in shearing association with the lower cutter; a roller; and means for mounting said roller on said presser foot for rotation about a substantially horizontal axis, the roller being in a position to extend laterally beyond the side edge of the presser foot and in front of the cutters so as to bear down on that portion of the material to be sewed which is trimmed off by the cutters, the roller having a small diameter portion adjacent the presser foot and a large diameter portion remote from the presser foot.

3. In a sewing machine, the combination of a lower feeder; a presser foot above the feeder; a lower stationary cutter alongside the feeder; an upper cutter in shearing association with the lower cutter; a roller; means for mounting said roller on said presser foot for rotation about a substantially horizontal axis, the roller extending beyond the side edge of the presser foot nearest the cutters and lying in advance of the cutters, the roller having a portion of small diameter adjacent said side edge and a large diameter portion at a greater distance from said side edge; and a stationary guide in advance of the roller and alongside the toe of the presser foot, the guide having a downwardly tapered trailing portion terminating at said roller, the width of said trailing portion being lms than the lateral reach of said roller.

4. In a sewing machine, the combination of a feed dog; a presser foot above said feed dog, said foot having an upwardly curved leading toe portion and a trailing heel portion, the foot being cut out to provide space through which the needle passes; means for hingedly mounting the foot about a transverse substantially horizontal hinge axis; a roller mounted on the foot for rotation about a substantially horizontal roller axis in advance of, and substantially parallel to, said hinge axis, said roller, extending beyond the left side edge of said foot and having a small diameter portion adjacent said edge and a portion of larger diameter at a greater distance from said edge than said small diameter portion; and a stationary guide in advance of the roller and alongside the toe of the presser foot, the guide having a downwardly tapered trailing portion positioned to the side of said feed dog, said trailing portion terminating at said roller, the width of said trailing portion being less than th lateral extent. of the roller beyond the side edge of the presser foot.

5. In a sewing machine, the combination of a feed dog; a presser foot above said feed dog, said foot having an upwardly curved leading toe portion and a trailing heel portion, the foot being cut out to provide space through which the needle passes and having a transverse recess in its top surface in advance of said space; means for hingedly mounting the foot about a transverse substantially horizontal hinge axis rearwardly of said recess; a bearing block mounted in said recess; a roller pivotally supported on said block about a substantially horizontal axis to extend beyond the left side edge of the foot, the roller having a small diameter portion adjacent said 5 6 block and a large diameter portion at a greater distance ing towards the straight side for progressively decreasing from said block than said small diameter portion; and a the width of the trailing portion which :at the end measures stationary guide in advance of said roller and alongside less than the distance of the large diameter portion of the the toe of the presser foot, the guide having a downwardly roller from said block. tapered trailing portion terminating at said roller, said trailing portion being located laterally adjacent said 5 References cued m the file of thls patent feed dog, said guide further having a substantially straight UNITED STATES PATENTS side substantially parallel to and alongside the said left 1,820,829 Ray Aug. 25, 1931 side edge of the foot and a second opposite side converg- 2,694,066 Knaus et a1 Aug. 18, 1953 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,034,460 May 15, 1962 John A. Wennstrom It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, .line 48, after "plate" insert 54 column 4, line 53, after "roller" strike out the comma.

Signed and sealed this 30th day of October 1962.

(SEAL) Attest:

ERNEST w. SWIDER ID LADD Attesting Office! Commissioner of Patents

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