US2421179A - Looper mechanism for sewing machines - Google Patents

Description

1 May 27, 1947.

L. .M. BALLAMY ET AL 1,179

LOOPER MECHANISM FOR SEWING MACHINES Filed Oct. 7, 1943 2 Sheets-Sheet l ay 27, 1947. L. M. BALLAMY ET AL 5 79 LOOI ER MECHANISM FOR SEWING MACHINES Filed Oct. '7, 1943 2 Sheets-Sheet 2 Patented May 27, 1947 LOOPER MECHANISM FOR SEWING MACHINES Leslie Mark Ballamy, Caterham, and Richard. Hasell Sheepshanks', Eyke, Wooclbridge, England Application October 7, 1943, Serial' No. 505,372 in Great Britain ()ctober 23, 1942 7 Claims.

This invention relates to looper mechanism for sewing machines and it has for its primary object to provide an improved form and construction of looper'mechanism which is exceptionally Simple to manufacture and is nevertheless reliable in operation.

In particular the invention is concerned with sewing machines of the form described in the specification of United- States of America Patent No. 1,622,774 which produces a form of chain stitch by employing upper and lower threads, both ofwhich are-fed directly from kops or other bulk supplies.

In the sewing machine described-in the abovementioned specification a needle mounted in a reciprocating needle bar serves tocarry the upper thread and pass it in andiout of the material to besewnLthelooper comprises a member disposed below the usualthroatplate of the sewing machineand. having a nose portion which is perforated to carry thelower thread-driving mechanism comprising. cranks and sliders being arranged to move the nose of the looper so that its executes a somewhat elliptical path around theaxis of reciprocation of. the needle, thereby passing thelower thread throughrthe loop which is.formed by the upperthreadduring eachpene- ,trat-ionand retraction of the needle.

It-is a further object of the invention-to simplify-this-mechanismand to provide an arrangementin which the'nu'mber of parts requiring lubrication is considerably reduced; also in the improved arrangement thefrictional resistance is verymuchless than in theprevious constructions, thus enabling. the sewing. machine to be driven with. less power.

In accordance with the invention looper mechanism. is provided for a sewing machine, said looper mechanism comprising an angularly movable armcarrying a-looper member, and a cam member which oscillates said arm in two mutually perpendicular planes.

There istfurther provided according to the. inventionlooper mechanism for a sewing machine comprisinganarm for manipulating the looper membenandarotatable cam formed with a cam track, which latter is engaged byla follower connectedwith the arm, said track serving to move the follower radially with respect to the axis of camlrotation, .and also in a lateral direction.hav ing a component parallel with saidaxis, both of said .movements taking place during eachoper- .ating cycle .ofthe mechanism.

Conveniently the cam is formed with aperipheral groove which constitutes a cam track and 2 is engaged by a follower comprising a projection carried by the arm. The bottom of the groove may position the follower in the radial direction, and at least one side of the groove-positions the follower laterally. Further, the follower may comprise a head upon a screw-threaded stem, which latter is fitted adjustably in the arm an'diis provided with locking means, said stem serving to regulate the position of the looper member for any given position of-the cam. Inthe' preferred construction the arm is pivotally mounted by means of av rubber or like flexible sleeve arranged to allow angular movement of the arm in a plane containing the axis of the sleeve, the material of the sleeve conveniently acting in torsion to allow angular movement of the arm about the axis ofthe sleeve. Where the axis of the'sleeve is substantially parallel withthe axis of rotation of the'cam, the sleeve may be stressed'in torsion when the mechanism is assembled, thus urging the follower resiliently into engagement withthe cam; A looper member may be carried by that end of the arm opposite to the pivotal mounting of'said arm, the follower being disposed substantially midway between the axis of pivotal mounting and'the looper member.

The invention is illustrated by way of example in the accompanying diagrammatic drawings, in which:

Figure 1 is an elevation of a looper mechanism as applied to a machine adapted to produce a plurality of rows of stitching simultaneously;

Figure 2 is anend elevation of the mechanism shown in Figure 1;

Figure 3 is afragmentary sectional elevation of the pivotal mounting of the looper arm drawn to an enlarged scale;

Figure 4 is a fragmentary plan of a modified form ofcam and follower device; and

Figure 5 is an elevation showinga convenient arrangement for use where a plurality of'looper mechanisms are required to operate simultaneollsly but with different phases.

Inthe arrangementshown in Figures 1 and 2 a-transverse table I0 is incorporated in the framework of the sewing machine and is formed in its upper surface with a longitudinal groove ll serving to locate a numberof bearing brackets, two of which are indicated at I2 and I3. The brackets l2 and it are securely clamped to the table Ill by bolts l4, and they carry a rotatable camshaft l5 arranged to be-continuously rotated conveniently through a toothed-clutch l6 of the ratchet type; the shaft 15 ismounted in the brackets l2 and [3 by ball or roller bearings (not shown) and carries a cam, which is indicated at I! and will be hereinafter described in detail. Also secured to the table I is a bracket iii of substantially U shape secured by a bolt I9 and located by a rectangular' projection 20 engaging within a groove 2! formed in the table. The bracket l8 serves as a pivotal mounting for a looper arm 22, which is substantially semi-circular in shape, as will be seen in Figure 2, and extends upwardly around the cam ll. The top of the looper arm 22 is fitted with a. transverse bar 23, which is conveniently secured by screws 24 and is drilled for the accommodation of a plurality of looper members 25 of the usual form, these being held in position each by a pair of grub screws 25. The looper members 25 co-operate with corresponding machine needles, one of which is indicated in broken lines at 21 in Figure 2, and said looper members are required to move around the needle axes by following an elongated orbit of approximately oval shape, said orbit being completed once for each cycle of movement of the machine needle 21.

In order that the desired movement of the looper arm 22 may be efiected in an extremely simple manner with very few moving parts, said arm is arranged to be oscillated in the plane of Figure 1 and simultaneously in the plane of Figure 2, both movements being effected by the cam IT. For this purpose the cam I1 is of substantially cylindrical form but is mounted eccentrically upon the shaft 15, as will be seen clearly in Figure 2. It is formed in its periphery with a groove 28, which, in radial section, is of substantially uniform depth and is somewhat semicircular in shape. This groove is engaged by a somewhat hemi-spherical head 29 fitted to a stem 30, which latter is screw-threaded into the looper arm 22 and is provided upon its projecting end 3| with a lock nut 32. A transverse slot 33 enables the stem 30 to be rotated and the position of the arm 22 relative to the head 29 to be adjusted finely thereby. The looper arm 22 is urged resiliently in a direction towards the cam 11 by means incorporated in the pivotal mounting of the arm, as will be hereinafter explained, and it will be seen, therefore, that the eccentric disposition of the groove 28 in the cam I1 brings about the main oscillation of the looper arm 22 in the plane of Figure 2. In order to bring about the simultaneous oscillation in the plane of Figure l the groove 28 undulates in an axial direction, as will be clear from Figure 1, in which the part of the groove 28 in the front of the cam is displaced to the left and the portion of the groove in the rear part of the cam is displaced to the right. The side walls 34 and 35, between which the head 29 fits snugly, are, of course, parallel with one another, and they may lie in planes which are disposed at the requisite inclination to the plane normal to the axis of the cam. It will be seen by comparison of Figures 1 and 2 that the positions of maximum axial deviation, indicated at 36 and 31, lie approximately upon the diameter 38 extending at right angles to the diameter 39 containing the axis of the shaft 15. As the follower constituted by the head 29 is disposed between the fulcrum at the lower end of the looper arm 22 and the looper members 25 at the upper end of the arm 22, it follows in practice that very little axial deviation or undulation of the groove 28 is required in order to make the looper members 25 pass around their respective needle axes for producing the usual stitching action.

The construction of the preferred form of pivotal mounting for the looper arm 22 is shown in Figure 3. The lower part of the arm 22 is provided with an integral tubular portion 40, which is split and provided with a tightening bolt 4! (see Figure 2) in order that it may be clamped around a resilient bearing unit indicated at 42. This bearing unit comprises an outer metal sleeve 43 and an inner sleeve 44, between which is disposed an annular bush 45 of soft resilient rubber or like material. The bush 45 is in a state of compression and/or is fastened to the sleeves 43 and 44, so that relative angular movement of the sleeves usually takes place by creating torsional stress in the bush 45. The sleeve 44 is secured by a bolt 46 passing through the limbs Isa and 18b of the bracket l8, said sleeve 44 being slightly longer than the sleeve 43, thus allowing it to be clamped firmly within the bracket l8 without hampering the movements of the looper arm 22. Owing to the provision of the resilient bush 45 the looper arm- 22 can move angularly about the axis of the bolt 46 (i. e., in the plane of Figure 2), and it can also oscillate sideways (i. e., in the plane of Figures 1 and 3). Further, by appropriately adjusting the arm 22 angularly around the sleeve 43 before tightening the bolt 4|, the resilience of the bush 45 is utilised to urge said looper arm 22 so that the head 29 is maintained in firm engagement with the cam ll; for instance, the desired adjustment can be obtained and the bolts 4| and 46 tightened while the bracket l8 and the looper arm 22 are removed from the table H].

In the modified form of device shown in Figure 4 the cam I7 is again substantially cylindrical in form and is mounted eccentrically upon the shaft !5. Its periphery, however, is formed with a circumferential rib or flange 41, which undulates in an axial sense and is engaged by a slotted cylindrical block 48 mounted within a head 29a formed upon the screw-threaded stem 30. The block 48 is thus free through any conventional mounting to move angularly about the axis of the stem 30 and to accommodate itself to the varying inclinations of the rib or flange 41. As will be clear from Figure 4, this rib or flange 41 does not lie in a single inclined plane, but is constituted by two portions 49 and 50 which lie in mutually parallel radial planes and are joined by relatively steep portions 5| and 52 arranged to move the looper members 25 at a rapid rate from one side of the needle axis to the other, such movement, of course, taking place in the plane of Figure 1. If desired the groove 28 of Figure 1 may be shaped in a similar manner.

Figure 5 shows a convenient arrangement which can be adopted where a number of looper arms 22a, 22b, 22c and 22d are disposed side by side and are required to be operated by a corresponding number of coaxial cams Ha, 1 lb, I10 and lld. Although the looper members 25 form an equidistantly spaced continuous series, the looper arms 22a etc. are arranged in pairs, each pair having between them a bearing bracket for supporting a common camshaft I5. Thus the bearing bracket between the arms 22a and 22b is indicated at 13a, while the one between the looper arms 22c and 22d is indicated at 13?). This enables the camshaft 15 to be rigidly supported adjacent each cam and at the same time requires only a small number of bearing brackets.

It will be understood that the constructions which have been described are given merely by way of example and that various modifications are possible.

What we claim is:

1. Looper mechanism for a sewing machine comprising a cam rotatable about an axis and having follower engaging surfaces for actuating the follower radially and axially of the cam, a looper supporting arm having a follower engagin said cam, and a resilient mounting for one end of said arm yieldably urging the follower into contact with the cam and permitting movement of the arm both radially and axially of the cam through corresponding movement of the follower.

2. A construction as defined in claim 1, wherein said follower comprises a head carried by one end of a stem having an adjustable threaded cooperation with the arm.

3. A construction as defined in claim 1, wherein the resilient mounting for the arm includes a metallic sleeve on which the arm is adjustably supported, and a resilient rubber bushing directly supporting the sleeve and held under compression by said sleeve.

4. A construction as defined in claim 1, wherein the arm' is curved in the form of an arc embracing the cam and extending partly around the circumference of the cam with the respective ends of the arms lying in a plane including the axis of the cam.

5. A looper mechanism for a sewing machine, comprising a continuously rotatable cam shaft, a cam mounted thereon and having a circumferential groove forming a cam track with mutually parallel side walls, an arm, a universal mounting for one end of the arm, a looper member carried by the other end of the arm, a cam follower projection carried by the arm between the universal mounting and the looper member and engaging the side walls of the cam track, said universal mounting including a resilient means urging the arm to hold the follower projection within the cam track, said cam track being eccentric with respect to the axis of the cam shaft and shaped to deviate axially from the truly circumferential direction whereby each turn of the cam moves the cam follower and the arm in two mutually perpendicular planes.

6. Looper mechanism for a sewing machine, including a cam member rotatable about an axis and having follower engaging surfaces for actuating the follower radially and axially of the cam memher, an angularly movable arm having a follower engaging said cam, a mounting at one end of the arm yieldably urging the follower into contact with the cam and permitting movement of the arm both radially and axially of the cam, and a looper member carried by the opposite end of the arm, the cam member cooperating with the arm at a point in the arm closer to the mounting than to the looper member.

'1. A construction as defined in claim 6, wherein said follower is supported by a stem adjustably engaged with the arm for adjustment of the follower radially of the cam.

LESLIE MARK BALLAMY. RICHARD HASELL SHEEPSHANKS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 946,064 Merrick Jan. 11, 1910 1,123,579 Onderdonk 1. Jan. 5, 1915 1,127,755 Gray Feb. 9, 1915

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