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Publication numberUS3053208 A
Publication typeGrant
Publication dateSep 11, 1962
Filing dateOct 20, 1959
Priority dateNov 11, 1957
Also published asDE1067669B, US2988030
Publication numberUS 3053208 A, US 3053208A, US-A-3053208, US3053208 A, US3053208A
InventorsEmerich Schenkengel, Rubi Schonthaler
Original AssigneePfaff Ag G M
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Freely rotating looper for sewing machines
US 3053208 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

Se t. 11, 1962 R. SCHONTHALER ETAL 3,053,208

FREELY ROTATING LOOPER FOR SEWING MACHINES Filed Oct. 20, 1959 2 Sheets-Sheet 1 35 FIG. 6 FIG. 8

Sept. 11, 1962 R. SCHGNTHALER ETAL 3,053,208

FREELY ROTATING LOOPER FOR SEWING MACHINES Filed Oct. 20. 1959 2 Sheets-Sheet 2 FIG. 9

Rubi SUIUWTHALER Emericb SCI/f/VKfA/GEL United States Patent Ofifice 3,053,208 Patented Sept. II, 1952 I 3,053,208 FREELY RQTATING LOOPER FOR EWING MACHINES Rubi Schonthaler and Emerich Schenkengel, Kaiserslantern Germany assi ors t G Kaisersilantern, Geirmany o M. Pfafi AUG.

lFiledUct. 20, 1959, Ser. No. 847,495 Claims priority, application Germany Oct. 21, 195% 7 Claims. (Cl. 112228) -ly of the looper and which, together with pins provided .on the looper casing, provide for axially resilient support of the retaining ring.

In accordance with another object of the invention a looper is provided for very high speed sewing machines in which the pins on the looper casing are provided with heads having a diameter which is greater than that of the width of the bayonet slots. This manner of construction prevents the tongues which are also radially resllient from being raised by the looper casing.

In accordance with a further object of the invention the incisions forming a continuation of the bayonet slots are utilized to cast off outwardly, immediately upon starting of the machine, any lubricant which has been collected between the looper casing and the retaining ring when the machine has not been used for a considerable length of time. In order to attain this objective the incisions extend from the bayonet slots obliquely forward so that their enlarged end is disposed proximate the front edge of the looper casing.

The looper cage, particularly the lower cage of a rotary looper, is normally provided with a thread rejecting flange which, when the upper thread is pulled upwardly by the thread feed, keeps the upper loop from the bearing rib of the bobbin cage and thus prevents that it picks up oil from the lubricated bearing rib. In a looper in accordance with the disclosure in Patent No. 2,988,030, the thread rejecting flange was intended to be made very short in order to facilitate the removal and insertion of the retaining ring. In accordance with the invention a part of the thread rejecting flange is to constitute a component of the upper cage, so that upon removal of the upper cage the removal and particularly the insertion of the retaining ring along a straight line from the front is furthermore facilitated while, on the other hand,

the engagement of the upper thread loop with the bearing rib is safely avoided. For use in a household ma chine which does not attain a very high number of rotations, the securing against displacement of the retaining ring may be omitted, especially where the additional necessary operation of this feature could only too readily be forgotten by the housewife. In that event the bayonet slots are provided at the point of transfer to the in- .cisions with a recess directed towards the back portion of the looper to receive the pins on the looper casing in a manner that the retaining ring is yieldingly held in its position.

Other objects and details of the invention will become apparent by reference to the drawings showing two embodiments and in which:

FIG. 1 is an exploded perspective view of a first embodiment of a looper,

FIG. 2 is a perspective illustration of the bobbin cage shown in FIG. 1,

FIG. 3 illustrates the bobbin casing in accordance with FIGS. 1 and 2 in separated condition,

FIG. 4 shows the member of the thread rejecting flange mounted on the upper cage,

FIG. 5 is a top view to an enlarged scale of the slide latch,

FIG. 6 is a section along line VIVI of FIG. 5,

FIG. 7 is a top view of the slide latch similar to FIG. 5,

FIG. 8 is a section along line VIIIVIII of FIG. 7,

'FIG. 9 is an exploded perspective view of a second embodiment of the invention without showing the upper cage, and

FIG. 10 is a view, partly in section taken along line X--X in FIG. 9, showing the looper in assembled condition on the looper shaft.

In the embodiment illustrated in FIGS. 1 to 8 the looper is provided with a looper casing, which is generally constructed in the same manner as that described in the aforementioned U.S. Patent No. 2,988,030. Accordingly, said looper casing has an offset shoulder 2, a mounting projection 3 for securing to the looper shaft and a looper point i.

In the looper casing 11. a bottom cage 5' is inserted in such a manner that the bearing rib 6 comes to rest against the shoulder 2 of the looper casing I. For the purpose of retaining the bottom cage 5 in this position, a retaining ring 7 is provided which is placed upon the looper casing and rests with its abutment surface 8 against the front edge 9 of the looper casing and extends with its angular portion into the interior of the looper cage in a manner that the angular portion 10 is at a radial distance from the inner surface 11 of the looper casing ahead of the shoulder 2. The border edge 12 of the angular portion 10 is disposed at an axial distance corresponding to the width of the bearing rib 6 ahead of shoulder 2, and together with the same forms the track for the bearing rib 6 of the bottom cage 5.

For the purpose of retaining the ring 7 on the looper casing 1 in the position described, radially outwardly extending pins 13 are provided on the casing which engage bayonet slots 14 of the retaining ring 7. The bayonet slots 14 are continued by small incisions 15. In this manner tongues 16 are formed which are adapted to flex in the axial direction of the looper, and in this manner permit the retaining ring 7 to move aside in an axial direction during casting of the thread. Inasmuch as tongues 16 are inherently adapted to resiliently yield also in a radial direction, and therefore have a tendency to lift themselves from the looper during operation at high velocities, the pins 13 are provided with heads 17, the width of which is greater than that of the bayonet slots 14-. Thus the heads hold down tong11es'16 also during operation at high velocities.

The incisions 15 extend obliquely from the bayonet slots 14 in the direction of the front end of the looper in a manner that their enlarged end 18 comes to rest proximate the front edge 9 of the looper casing 1 when the retaining ring 7 is in position. In this manner these slots are adapted to serve in connection with permanently lubricated loopers, where after the sewing machine has been standing idle for a long period of time lubricant has collected between the looper casing 1 and the retaining ring 7, to cast off the lubricant at once outwardly as the machine is started.

It should not be possible to turn the retaining ring 7 unintentionally with respect to the looper casing 1, because this involves the danger of release during operation. For this purpose a cutout 20 is provided in the rear edge 19 of the retaining ring 7 into which fits an angular lug 21 of a sliding latch 22. The latter is frictionally guided in a dovetail slide 23 of the looper casing. If the sliding latch 22 is in the position shown in FIGS.

1, 5 and 6, then its lug 21 is disposed externally of the cutout or recess 20 of the retaining ring 7, and it is possible to the extent permitted by the bayonet slots 14 to turn the ring with respect to the looper casing 1. However, if the lug 21 abuts the back end of the looper casing 1, then it is located in the cutout 20 of the mounted retaining ring 7, thereby securing said ring in its locking position against rotary displacement.

In accordance with FIGS. 5 and 6 a screw 24 is threadedly mounted in the wall of the looper casing 1 in a manner that its threaded portion 25 extends into the dovetail slide 23. A longiutdinal slot 26 in the sliding latch 22 of the diameter of the threaded portion 25 extends into a slot 27 of smaller width whereby the possibility of movement of the sliding latch 22 toward the right is limited. The slot 27 furthermore defines two legs 28 on the sliding latch 22 which by virtue of their outwardly directed inherent resiliency are frictionally guided in the dovetail slide 23. In accordance with FIGS. 7 and 8 the screw 24 may also be threaded into the wall of the looper casing 1 from the outside. For this purpose the sliding latch 22 is provided with a circular cutout 29 connecting with slot 26 to receive the head 30 of screw 24 which has a diameter corresponding to this cutout.

If the screw 24 is inserted into the wall of the looper casing 1 from the inside, as illustrated in FIGS. 5 and 6, then the sliding latch 22 may be shifted into and out of position of operation. However, if screw 24 is inserted into the wall of the looper casing 1 from the outside, as shown in FIGS. 7 and 8, then it locks with its head 30 the sliding latch 22 in its operative position in a manner that the retaining ring 7 is secured against rotary shifting, as previously explained. In the position of the screw 24 in accordance with FIGS. 7 and 8, the retaining ring 7 may only be removed with the aid of a screwdriver. To permit the use of a screwdriver the cutout 20 in the retaining ring 7 is enlarged by means of a semicircular cutout 31.

The bottom cage 5 is provided with a thread rejecting flange 32 which is shortened and already terminates at the edge indicated by reference numeral 33. This affords the possibility of drawing the retaining ring 7 upon unlatching from the looper casing 1 in a straightforward direction and also to remount it again along a straight line. However, to insure that the upper thread loop does not pick up oil from the bearing rib 6, a small plate 35 is secured to the upper cage 34 by means of two screws 36. The end 37 of the plate 35 on inserting the upper cage 34 in the lower cage 5 engages the border edge 33 of the thread rejecting flange portion 32 in a manner that the parts 32 and 35 as illustrated particu larly in FIG. 2 together form a continuous thread rejecting flange of known function.

A different embodiment is shown in FIG. 9 which is advantageous in connection with machines which operate at lower velocities, for example household machines, because it is simpler in construction as compared with the first embodiment.

Similar to the first embodiment, a looper casing 101 is provided on which are arranged pins 113 for cooperating with the bayonet slots 114 of the retaining ring 107. The bayonet slots 114 are continued by incisions 115, thus forming tongues 116 which are resilient in axial direction.

The construction of the retaining ring 107 proper is essentially the same as that of retaining ring 7. The bayonet slots 114 in addition are merely provided with recesses 138 along the side facing the back end of the looper in which the rigidly mounted pins 113 are yieldingly retained in the locking position of the retaining ring 107.v

With machines running at slower speeds this arrangement is already sufficient for preventing the unintentional releasing of the retaining ring 107. For easier manipula- 4- tion the retaining ring 107 is also provided at its circumference with a knurled portion 139. FIG. 9 shows merely the bottom cage 140 of the bobbin cage.

Having now described our invention with reference to the embodiments disclosed herein and shown in the accompanying drawings, we do not wish to be limited thereto, but what we desire to protect by Letters Patent of the United States is set forth in the appended claims.

We claim:

1. Freely rotating looper for sewing machines having a looper shaft, said looper comprising a looper casing having a rearwardly extending mounting projection adapted to be mounted on the looper shaft of the machine and a wall portion of cylindrical conformation presenting a front edge, a looper point and a shoulder defined inwardly of said front edge, mounting pins extending radially of said casing, a looper cage received in said casing having a bearing rib engaging said shoulder, and a slidingly removable retaining ring having a cylindrical portion slidingly received over said cylindrical wall portion and said looper cage and presenting an abutment surface engaging said front edge, an angular portion and an inner border edge defining in combination with said shoulder on said casing a track for said bearing rib, said cylindrical portion of said slidingly removable retaining ring having bayonet slots for engagementwith said pins to retain said ring and thereby said cage on said casing, and incisions in said cylindrical portion extending from the closed ends of said bayonet slots to a position radially outwardly of said front edge and defining resilient tongues on said retaining ring effective in combination with said pins to provide for axially resilient mounting of said retaining ring on said casing.

2. Freely rotating looper for sewing machines having a looper shaft, said looper comprising a looper casing having a rearwardly extending mounting projection adapted to be mounted on the looper shaft of the ma chine and a wall portion of cylindrical conformation presenting a front edge, a looper point and a shoulder defined inwardly of said front edge, mounting pins extending radially of said casing, a looper cage received in said casing having a bearing rib engaging said shoulder, and a slidingly removable retaining ring having a cylindrical portion slidingly received over said cylindrical Wall portion and said looper cage and presenting an abutment surface engaging said front edge, an angular portion and an inner border edge defining in combination with said shoulder on said casing a track for said bearing rib, said cylindrical portion of said slidingly removable retaining ring having bayonet slots for engagement with said pins to retain said ring and thereby said cage on said casing, and incisions in said cylindrical portion extending from the closed ends of said bayonet slots to a position radially outwardly of said front edge and defining resilient tongues on said retaining ring effective in combination with said pins to provide for axially resilient mounting of said retaining ring on said casing, said pins being threadedly received in said looper casing and having heads of a diameter greater than that of said bayonet slots.

3. Freely rotating looper for sewing machines having a looper shaft, said looper comprising a looper casing having a rearwardly extending mounting projection adapted to be mounted on the looper shaft of the machine and a wall portion of cylindrical conformation presenting a front edge, a looper point and a shoulder defined inwardly of said front edge, mounting pins extending radially of said casing, a looper cage received in said casing having a bearing rib engaging said shoulder, and a slidingly removable retaining ring having a cylindrical portion slidingly received over said cylindrical wall portion and said looper cage and presenting an abutment surface engaging said front edge, an angular portion and an inner border edge defining in combination with said shoulder on said casing a track for said bearing rib, said cylindrical portion of said slidingly removable retaining ring having bayonet slots for engagement with said pins to retain said ring and thereby said cage on said casing, and incisions in said cylindrical portion extending from the closed ends of said bayonet slots to a position radially outwardly of said front edge and defining resilient tongues on said retaining ring effective in combination with said pins to provide for axially resilient mounting of said retaining ring on said casing, said incisions extending obliquely forward from said bayonet slots and having each an enlarged portion endwise thereof proximate said front edge of said looper, casing.

4. Freely rotating looper for sewing machines having a looper shaft, said looper comprising a looper casing having a rearwardly extending mounting projection adapted to be mounted on the looper shaft of the machine and a wall portion of cylindrical conformation presenting a front edge, a looper point and a shoulder defined inwardly of said front edge, mounting pins extending radially of said casing, a looper cage received in said casing having a bearing rib engaging said shoulder, and a slidingly removable retaining ring having a cylindrical portion slidingly received over said cylindrical wall portion and said looper cage and presenting an abutment surface engaging said front edge, an angular portion and an inner border edge defining in combination with said shoulder on said casing a track for said bearing rib, said cylindrical portion of said slidingly removable retaining ring having bayonet slots for engagement with said pins to retain said ring and thereby said cage on said casing, and incisions in said cylindrical portion extending from the closed ends of said bayonet slots to a position radially outwardly of said front edge and defining resilient tongues on said retaining ring effective in combination with said pins to provide for axially resilient mounting of said removable retaining ring on said casing, said pins being threadedly received in said looper casing and having heads of a diameter greater than that of said bayonet slots, said incisions extending obliquely forwardly from said bayonet slots and having each an enlarged portion endwise thereof proximate said front edge of said looper casing, said looper casing having a groove of dovetail conformation extending longitudinally thereof and a sliding member having an outwardly extending lug and said removable retaining ring having a cut-out portion at the inner edge of said cylindrical portion adapted to receive said lug.

5. Freely rotating looper in accordance with claim 4, wherein said sliding member define a circular cut-out and a retaining screw is threadedly received in said casing, said screw having a head of a diameter corresponding to said cut-out, a longitudinal slot extending from said cut-out and having a width corresponding to the threaded portion of said screw and a further slot of lesser width dividing said sliding member into two legs resiliently guided in said groove.

6. Freely rotating looper in accordance with claim 5, including said looper cage and a rejecting flange for the upper thread and wherein said flange is formed as a part of the upper portion of the looper cage.

7. Freely rotating looper for sewing machines having a looper shaft, said looper comprising a looper casing having a rearwardly extending mounting projection adapted to be mounted on the looper shaft of the machine and a wall portion of cylindrical conformation presenting a front edge, a looper point and a shoulder defined inwardly of said front edge, mounting pins extending radially of said casing, a looper cage received in said casing having a bearing rib engaging said shoulder, and a slidingly removable retaining ring having a cylindrical portion slidingly received over said cylindrical wall portion and said looper cage and presenting an abutment surface engaging said front edge, an angular portion and an inner border edge defining in combination with said shoulder on said casing a track for said bearing rib, said cylindrical portion of said slidingly removable retaining ring having bayonet slots for engagement with said pins to retain said ring and thereby said cage on said casing, and incisions in said cylindrical portion extending from the closed ends of said bayonet slots to a position radially outwardly of said front edge and defining resilient tongues on said retaining ring effective in combination with said pins to provide for axially resilient mounting of said removable retaining ring on said casing, and a recess defined intermediate said bayonet slots and said incisions adapted to receive said pins.

References (Iited in the file of this patent UNITED STATES PATENTS 2,102,954 Hohmann Dec. 21, 1937 2,469,517 Petskeyes May 10, 1949 2,839,019 Heimann et al. June 17, 1958 FOREIGN PATENTS 1,053,293 Germany Mar. 19, 1959

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2102954 *Mar 2, 1937Dec 21, 1937Hohmann Richard KRotary loop taker
US2469517 *Mar 8, 1948May 10, 1949Gellman Mfg CompanySewing-machine loop taker
US2839019 *May 11, 1954Jun 17, 1958Pfaff Ag G MHook for double stitch sewing machine
DE1053293B *Nov 11, 1957Mar 19, 1959Pfaff Ag G MFrei umlaufender Greifer fuer Naehmaschinen
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4757774 *Apr 22, 1981Jul 19, 1988Kochs Adler AgNeedle guide in a sewing machine
EP0457376A2 *Feb 26, 1991Nov 21, 1991Hirose Manufacturing Company LimitedFull rotary hook
Classifications
U.S. Classification112/228
International ClassificationD05B57/14, D05B57/00
Cooperative ClassificationD05B57/14
European ClassificationD05B57/14