US2851978A

US2851978A - Sewing machines

Info

Publication number: US2851978A
Application number: US344560A
Authority: US
Inventors: Eriksson Allan Herman
Original assignee: Husqvarna Vapenfabriks AB
Current assignee: Husqvarna Vapenfabriks AB
Priority date: 1952-03-26
Filing date: 1953-03-25
Publication date: 1958-09-16
Anticipated expiration: 1975-09-16
Also published as: GB725349A; BE518700A; DE1007604B; CH325421A; FR1073241A; NL107894C; NL177101B

Description

Sept. 16, 1958 Filed March 25. 1953 A. H. ERIKSSON SEWING MACHINES 2 Sheets-Sheet 1 Sept. 16,.1958 A. H. ERIKSSON 2,851,978

SEWING MACHINES Filed March 25. 1953 u 2 Sheets-Sheet 2 ATTORNEY United States Patent SEWING MACHINES Allan Herman Eriksson', Huskvarna', Sweden, assignor to Husqvarna Vapenfabriks Aktiebolag, Huskvarna, Sweden, a corporation of Sweden Application March 25, 1953, Serial No. 344,560 Claims priority, application Sweden March 26, 1952 9 Claims. (Cl. 112-232) This invention relates to stitch forming mechanisms for sewing machines, and more particularly to lock stitch formmg mechanisms-of the type comprising a-reciprocating needle bar and a rotary shuttle, housing a nonrotating spool case and having a loop taker hook at its circumfer-.

in the risk of jamming threads is excluded and the friction is reduced to a minimum. A further object of the invention is to provide a novel shuttle mechanism without raceway wherein the case with a spool therein may readily be taken out.

With the above and other objects in view, as will hereinafter appear, the invention comprises the novel com binations and arrangements-of parts hereinafter set forth and illustrated in the accompanying drawings, and the advantages attained thereby will be readily understood by those skilled in the art.

The invention will be more particularly described in the following with reference to the annexeddrawing illustrating an application of the inventionto a lock-stitch sewing machine with a cantilevered fabric supportingarm.

Fig. l is a schematic end view of the machine, partly in cross-section through the supporting arm. Fig.- 2 is a front view of the stitch forming mechanism disposed in the free end of the supporting arm. Figs. 3-5show the shuttle in three different projections. Figs. 6 and 7 show the shuttle driving member in front and'side view, respectively. Fig. 8 is a plan view of its retaining member and Fig. 9 a side view of the spoolcase. Figs. 10-12 show the shuttle, its driving member and the spool case in three different working positions. Figure 13 is an axial vertical section through the shuttle and thedriver when about in the position corresponding to the top most position of the needle which is occupied somewhat after the position shown in Figure 12, the section being taken between the hook and the lug, and Figure 14 is a sectional detail illustrating the latching of the spool holder or case to the shuttle.

The frame of the machine shown comprises a standard 1, a cantilevered fabric supporting arm 2 and a needle head 3 disposed above the arm 2 and'carryihg a vertically movable needle bar 4 with a needle 5, a thread takeup lever 6 and other known means (not shown) for conducting the upper thread from a thread reelt'o the fabric. The supporting arm 2 houses means for feeding the fabric in the transverse direction of the arm, towardsthe left in Fig. l which means may be of known construction and are therefore not shown, as well aslower stitch'forming means available through an opening 8 in the supporting arm which is provided with a lid 7 for said opening and with a stitch plate 9.

The said stitch forming means comprise a substantially cup-shaped shuttle 20, Figs. 3-5, having a central pivot 21 for a spool case, apreferably substantially circular-circumferential-flange 22 wherein a loop taker hook 23 is formed, and an annular, axially acting cam 25 for operating the under thread, said cam being provided with a peripheral slot 24 for the needle. The shuttle 20 is supported at its circumference between a substantially concave member 30 for carrying and driving the shuttle, and a stationary retaining member supporting the shuttle 20 axially, preferably a substantially ring-shaped cover plate provided with a recess '41 for the needle on its side facing the shuttle-20, Pig. 8. The driving member 30 shown is provided on its circumference with axially as Well as radially extending

bearing surfaces

31 and 32, respectively, for the shuttle flange 22, and with a seat recess 33 to receive a lug 26 on the shuttle 2t) laterally of the flange 22 for transmitting movement from member 30 to shuttle 20.

In the embodiment shown the shuttle 20 is adapted to rotate about a horizontal axis parallel to the fabric feeding direction, the driving member 39 being mounted on a transverse shaft 10 journaled in the supporting arm 2 and, preferably by means of a bevel gear 11, connected to a drive shaft 12 extending longitudinally in the supporting arm 2. The movement of this shaft 12 is preferably such that the shuttle 29 rotates with constant (uniform) speed in the clockwise direction in Fig. 2, making two revolutions for each up and down movement of the needle. The movement transmitting lug 26 should belocatedconsiderably less than 90 in front of the hook 23. The retainer 40 is detachably secured by means of screws-13 to a member 14 rigidly mounted in the supporting arm 2. The shuttle 2% should have an axial play between the members 30 and'40 corresponding to the maximum thread thickness to be used, and may also have some play perpendicularly thereto. The shuttle bearing parts of the driving member 30 and/ or the retainer 40 arepreferably of a more sound-deadening material than solid metal, such as porous sinter metal or, better, a nonmetallic material, such as a plastic. The driving member 30 may wholly consist of a plastic, such as nylon or textilearmoured Bakelite, and the retainer it) may be provided with a lining 42 thereof. Alternatively, the bearing part of the shuttle 24 the flange 22 may be of such material.

The spool case should be substantially smoothon its outer end surface to be passed by the upper-thread. The spool case shown in Fig. 9, for a conventional under-thread spool not shown, has a cylindrical mantle 50 and a bottom part 51 remaining between two diametrically opposite openings and shaped to form afinger grip, said part 51 carrying a central, tubular'shank '52 fitting inthe spool and on the pivot 21 of the shuttle, said pivot 21 having a peripheral groove 27 on its free end. A locking member 54, 55' mounted inside :the bottom part 51 and preferably swingable. on a pivot 53, is adapted to engage into the groove 27 with .the part 54 under the pressure of a spring 56, Fig. 2, whereas the other part 55 is adapted to be manually operated when gripping the bottom part 51, whereby the spool case can be released from the shuttle 20 and the part 55 will engage the adjacent edgeof the spool with its inturned free end, particularly visible in Fig. 9, thereby retaining the spool in the spool case. The mantle 50 of the case is provided at its top with anopening 57 for the needle and upon one side with a thread tensioning leaf: spring 58 covering a through-hole for the under thread;'this latter feature being well-known in the art and therefore not particularly shown in the drawing. The spool case also has a finger 59 which is formed on the

locking member

54, 55 and project through the opening 57 but which, preferably, is rigidly mounted on the case, said finger engaging, with some play, into a recess 43 formed in the upper part of the retainer 40, Fig. 2, the edges of the recess 43 adjacent the shuttle 20 being preferably chamfered in known manner in order to facilitate the passage of the upper thread. If desired, this recessed upper part of the retainer 40 may be formed integral with the lining 42.

The operation of the mechanism described is illustrated by Figs. -12, wherein a denotes the upper thread and b the under thread which is assumed not yet to have been fastened in the fabric. Moving downwards the needle enters the slot 24 in the shuttle, the flange 22 of which is preferably somewhat charnfered at the location 28, Fig. 3, passed by the point of the descending needle. Extending into said slot 24 the needle is capable of keeping the shuttle in an axial position wherein the book 23 will not strike the needle, a part 22a extending in front of the hook 23 being adapted to engage the side of the rising needle when the hook 23 is about to pass the same. The preceding part of flange 22 may be provided with a slight axial depression 28a in order to eliminate or reduce the contact between the flange 22 and the very eye-part of the needle. In Fig. 10 the hook 23 has just passed the needle which has moved upwardly, forming a thread loop for which ample space may be provided by an axial depression 34 in the circumference of the driver 30, Fig. 6, and which is taken by the hook 23. By further rotation of the shuttle the loop is widened and thrown around the spool case, the loop passing freely past the outside of the bottom of the spool case and the shuttle 20. In order to facilitate the thread running on the shuttle bottom, the driver 30 is provided with an axial depression 35 laying the flange 22 bare at a part of its circumference to be passed by the upper thread at the instant in question. While the shuttle 20 is moving from the position in Fig. 11 to the position in Fig. 12, the upper thread a is tightened by the take-up lever 6, the thread passing easily the lug 26 and leaving the shuttle 20 while embracing the under thread b. When the latter has been fastened in the fabric, it is pulled forward by the cam which for this purpose is of varying height axially. When being tightened, the upper thread a passes between the under thread b and the edge of the hole in the stitch plate. In order to facilitate this passage, the cam 25 is provided with a depression 29 at the part of its circumference engaging the thread during said passage, whereby the tension of the under thread b will be reduced for the moment in question.

The three main cooperating elements are the shuttle 20, the driving member 30 and the fixed retainer or annular cover plate 40. The shuttle 20 includes a concave or dished body which is circumscribed by the flange 22 and the driving member is of concave or dished form for receiving the dished body of the shuttle. The said flange is supported in the seat provided by the

bearing surfaces

31 and 32 and the retaining and driving members are so spaced that the intervening shuttle has limited axial movement for passage of the inner limb of a needle thread loop between the driving member and shuttle. Furthermore, the recess 33 in the driving member is slightly wider than the shuttle lug 26 for passage of said thread loop limb upon slight relative circumferential movement of the driving member and shuttle. The outer limb of said needle thread loop passes over the bobbin casing or mantle 50 and between the finger 59 and its receiving recess 43 in which the finger has slight circumferential movement. p

The stitch forming mechanism described is particularly suitable for domestic sewing machines and may be used to advantage also in zigzag sewing machines wherein the needle bar is in known manner movable in a plane perpendicular to the fabric feeding direction. In said mechanism the upper thread does not have to lift some part of the mechanism. The risk of jamming threads is excluded, and the friction is reduced to a minimum. At the exchange of spools the spool case with a spool therein may readily be taken out through the opening in the ring-shaped retainer 40 which, consequently, does not have to be removed for changing spools.

Also various other embodiments are possible within the scope of the invention. The shuttle may, for instance, also be mounted for rotation in a vertical plane through the fabric feeding direction.

What I claim is:

1. A stitch forming mechanism, comprising in combination, a rotary shuttle including a circumferential flange provided with a loop taking book, a shuttle driving member adapted for continuous rotary movement and provided circumferentially thereof with axial and radial bearing surfaces defining a seat for said shuttle flange, said shuttle and said driving member being provided with cooperating rotation transmitting means, and a stationary member disposed adjacent said flange in opposition to said driving member for confining said shuttle for rotation with said driving member with limited axial play between the said radial bearing surface and said stationary member.

2. In a sewing machine, the combination of a vertically reciprocating needle bar, a rotary shuttle having a circumferential flange provided with a loop taking book, a shuttle driving member supported for rotation in a plane parallel to said needle bar and provided circumferentially thereof with axial and radial bearing surfaces defining a seat for said flange, said shuttle and said driving member being provided with cooperating rotation transmitting means, and a stationary member disposed adjacent said flange on the side thereof opposite said driving member and being spaced from said radial bearing surface a distance slightly greater than the thickness of said flange for bodily axial movement of said shuttle in said driving member for passage of the inner limb of a needle thread loop therebetween.

3. In a lock stitch sewing machine, a shuttle comprising a dished body having a peripheral flange encircling same for the major circumference thereof, a bobbin case pivot stud projecting from the base of said body in the axis of rotation of the shuttle, one end of said flange being provided with a loop taking hook, a rotation transmitting lug on the opposite end of said flange, a driving member having a recess in which said lug is loosely received and said flange being provided with a peripheral depression adjacent said rotation transmitting lug.

4. A stitch forming mechanism, comprising in combination with a vertical reciprocating needle, a dished shuttle driving member having the base thereof secured to a rotary shaft disposed at right angles to said needle, a rigidly supported annular cover plate disposed in spaced parallel relation to said driving member, and a dished shuttle disposed between said driving member and said cover plate, said driving member having an annular seat and a recess in the annular wall thereof, said shuttle having an annular flange with one side thereof engageable with said seat, and having a lug loosely supported in said recess for passage of the inner limb of a needle thread loop past same, and said cover plate being disposed in such spaced relation to said driving member for slight axial movement of said shuttle for passage of said thread loop limb between the base thereof and the base of said driving member.

5. A stitch forming mechanism according to claim 1 in which said rotation transmitting means comprises a rotation transmitting lug projecting from one of said shuttle and driving member and the other of said shuttle and driving member having a recess loosely receiving said lug and wherein said shuttle is of metallic material and said driving member is of non-metallic material having characteristics for deadening sound occasioned by axial impact between the shuttle and shuttle driving member and rotary impact between the lug and the wall of said recess.

6. A stitch forming mechanism according to claim 1 wherein said shuttle is adapted to support a bobbin case having a rotation restraining finger, and wherein said stationary member is provided with a recess loosely receiving said finger, and said stationary member being of non-metallic material for sound deadening of impact between said finger and the wall of said recess.

7. A stitch forming mechanism'according to claim 1, wherein surfaces of contact between said shuttle and said members are formed by parts of a material having characteristics for deadening sound occasioned by axial impact between the shuttle and said members.

3. A stitch forming mechanism according to claim 1, wherein the shuttle has a guide part extending from the base of said hook in the direction of movement thereof and adapted to engage one side of the needle when the hook is about to pass the same, so as to keep the hook from striking the needle due to said axial play of the shuttle.

9. A sewing machine according to claim 2, wherein said rotation transmitting means comprises a rotation transmitting lug projecting from said flange, said driving member having a recess loosely receiving said rotation transmitting lug, said recess being disposed in advance of said loop taking hook at an angle less than and wherein the driver has a uniform rotary movement and is adapted to make two revolutions at each reciprocating movement of the needle bar.

References Cited in the file of this patent UNITED STATES PATENTS