US2034706A - Sewing machine - Google Patents

Description

March 24-, 1936. R. BECKER 2,034,766

SEWING MACHINE Filed April 2, 1935 4 Sheets-Sheet 1 awe/whom Rudolph Becker arch 24, 1936. RJBEQKER 2, 4,7

" SEWING-MACHINE Filed April 2, 1935 4 Sheets-Sheet 2 6 60 I Rudolph Becker 7 Z .ei

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March 24, 1%3fi. R BECKER 2,034,7U6

SEWING MACHINE Filed April '2, 1935. 4 Sheets-Shet s March 24, 1936.

R. BECKER SEWING MACHINE Filed April 2, 1935 4 Sheets-Sheet 4 udoZp/a 560 597 Patented Mar. 24, 1936 UNITED STATES PATENT OFFEQE SEWING MACHINE Application April 2, 1935, Serial No. 14,217

6 Claims.

This invention relates to sewing machines, more particularly of the type adapted to sew straw braid in the formation of hats; a machine of this type being disclosed in United States Pat- I ent No. 1,429,399, dated September 19, 1922.

A machine of the type in question is customarily provided with a pair of side-by-side needles which are carried by the same vertically reciprocatory needle-bar mounted below the work-supporting v10 plate; one of said needles being a hook-needle and the other an eye-pointed needle. The needles are projected upwardly through the work on the up-stroke of the needle-bar and they cooperate above the work with suitable loopers one of which seizes a loop of the sewing thread from the eyepointed needle and the other of which assists in presenting the seized loop to the hook-needle which pulls the loop of thread downwardly through the work and presents it at the under side of the work for entry by the eye-pointed needle and to provide the machine with a variable needle-bar-actuating mechanism controlled by the looper-supporting slide-frame so that the upstroke of the needles will be increased correspondingly with the elevation of the looper-sup- 35 porting slide-frame.

-In the operation of a machine of this nature at speed, centrifugal forces are set up in the needle-bar-actuating mechanism which have a tendency to react through the controlling connec- 40 tions with the looper-supporting slide-frame and lift the latter, together with the presser-foot, from the work. To overcome this tendency it has been proposed to apply a strong spring to resist it, but the application of such a spring is dis- 45 advantageous in the sewing of fragile strawbraids at low or moderate speeds, as in starting the button or central portion of the crown of a hat, since the strong spring required exerts a down force upon the presser-foot which is destructive to the braid.

The present invention has for an object to provide a straw-braid sewing machine with an improved variable needle-bar-actuating mechanism which is controlled by the looper-support- ,55 ing slide-frame and in which reactionary forces tending tolift the looper-supporting slide-frame have been materially reduced. A further object of the invention is to provide for a limited vertical movement of the presser-foot under alight spring pressure independently of the more strong- 5 1y biased looper-supporting slide-frame, for the sewing of thin fragile braids. Still further, the invention has for an object to provide manually operated means for setting the locper-supporting slide-frame at any desired working elevation. 10

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of'a preferred em- 15 bodiment' of the invention, from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

Referring to the accompanying drawings, Fig. 20 1 is a longitudinal vertical sectional view of a straw-braid sewing machine embodying the invention. Fig. 2' is a front end elevation of the machine. Fig. 2a is a'detail view of the looperactuating mechanism. Fig. 3 is a top plan view of the free end-portion of the overhanging bracket-arm of the machine. Fig. 4 is a horizontal section through the machine bed showing parts of the needle'-baractuating' mechanism in plan. Fig. 5 is a vertical transverse section through the bracket-arm of the machine adjacent the looper-supporting slide-frame and. presser bar. Fig. 6. is a perspective View of the presser-foot and presser-bar, and Fig. 7 is a section substantially on the line 'l1, Fig.1, and Fig. 8 is a detail view of the anchorage for the presser-bar scpring of the machine.

The machine is constructed with a frame including the bed I and standard 2 of the overhanging bracket-arm 3 terminating in the head 40 4. Journaled in the bed i is the main shaft 5 having the needle-bar driving ball-crank 5 which is connected by the pitman l to the ball 8 at the rear end of the cylindrical rod or lever 9 slidably mounted in the fulcrum guide-sleeve in the central portion II of which is of cubical form and has projecting from its lateral faces the alined pivot-studs I2 journalled in the side-blocks H which work in the guideways i l in the bed I. The slide-blocks l3 contact the side faces of the cubical central portion ll of the fulcrum-sleeve I0 and are held on the pivot-pins l2 by the cap-screws l5.

At its forked forward end the lever-9 is connected by the pivot-pin Hi to the'lower end -0f the elbow-shaped arm I! rigid with the needlebar I 8 which is mounted for vertical reciprocation in the guideway H9 in the bed I. The needlebar l8 carries the usual hook-needle 2i! and eye pointed needle 2! arranged in side-by-side relation in the holder 22 fixed to the needle-bar. The lever 9 has fixed to it, adjacent its opposite ends, the guide-blocks 23 which work in vertical guideways between the guide-bars 24.

It will be understood that the length of the stroke imparted to the needle-bar [8 by the crank 6 will depend upon the position of the fulcrumstuds I2 and their bearing blocks E3 in the guideways 14. Further, it will be observed in Fig. 1 that when the crank 6 is at its highest point and the needle-bar I8 is at the lower limit of its stroke, the lever 53 is in parallelism with the guideways l4 which are inclined downwardly from their rearward ends toward the pivot l5.

One of the slide-blocks l3, Fig. 1, is connected by the link 25 to one arm 25 of a bell-crank lever fulcrumed on the pivot-stud 2'l which projects inwardly from the front wall of the bed I. The other arm 28 of the bell-crank lever is connected by the pitman 29 to the two-piece crank-arm 35 of adjustable length fixed to the rearward end of the rock-shaft 3! to the forward end of which is fixed the crank-arm 32 connected by the link 33 to the looper-carrying slide-frame 34 which is movable vertically in the head 4 at the free end of the overhanging bracket-arm 3.

The loopers 35, 3,5 which are carried by the slide-frame 34 and cooperate with the needles 20, 2| are preferably constructed and operatedsubstantially in accordance with the disclosure of U. S. Patent No. 1,429,399, previously referred to. The looper 35, which seizes a thread-loop from the eye-pointed needle 2! and moves in a plane at one side of and parallel to the plane of the needles, is mounted on the looper-lever 31 which is fulcrumed at 38 in the slide-frame 34. The looper 36, which carries one limb of the seized thread-loop into the barb of the hook-needle 20, is mounted on the looper-carrier 39 which rocks on the pintles 40 and receives motion from the looper-lever 31 through the connecting link 4!. The looper mechanism is actuated in the usual manner, as disclosed in said U. S. patent, by a crank-arm 42 on a rock-shaft 43 within the bracket-arm 3; the crank-arm .2 being pivotally connected at its lower end to a slide-block 44 embracing the looper-lever 31.

Slidably mounted in the head 4, alongside the looper-supporting slide-frame 34, is the presserbar 45 carrying the usual presser-foot 45. The presser-bar 45 has rigidly secured thereto an arm 41 having at its free end a roller 48 in position to be engaged by the usual manually operated presser-bar-lifting cam lever 49. The arm 41 has an upstanding branch 50 which is apertured at 5|, Fig. 6, to receive the free end of a cantilever spring 52 anchored at its rear end 52 in the internal frame-lug 53 and carrying a guide-block 54, Fig. 1, having a non-threaded hole receiving the lower end of the presser-spring adjusting screw 55. The presser-bar 45 has a limited vertical movement unaccompanied by movement of ent vertical movement of the presser-bar 45 there is provided on top of the bracket-arm head 4 a stop-cam 51 in the form of a disk adjustable circularly about its supporting screw stud 58 and formed with a spiral stop-face 59 which is engaged by the overhanging arm 50 rigidly secured to the slide-frame 34. A relative strong spring 6f anchored at one end to the eyelet 62 adjustably mounted in the slot 63 in the frame and at itsother end to the bell-crank lever-arm 25 in the base of the machine, yieldingly retains the slideframe arm 50 in engagement with the stop 51. Thus, the force of the relatively strong spring BI is not transmitted to the presser-foot and work under it except possibly when the work exceeds a certain thickness determined by the adjustment of the stop 51. The relatively light presser-foot and barare thus free to follow the rising and falling movements of the feed-dog 62 of the machine, while the slide-frame 34 normally remains stationary during the sewing; being lifted only when the operator manipulates the cam-lever 49 to raise the presser-foot 46 for insertion or removal of work.

To minimize friction between the presser-bar 45 and the slide-frame 34, roller bearings 64 are provided as shown in Fig. 2. These roller bearings prevent cramping of the presser-bar against the slide-frame under the lifting movement occasioned by the rising feed-dog 65 and the lowering movement occasioned by the spring 52. The application of the spring 52 to the forwardly eXtend-. ing arm 41, so that the spring is applied to the. presser system at a point substantially verticallyover the point of application of the upward pressure of the feed-dog 65 also reduces the tendency of the presser-bar to cramp sidewise against its guiding walls. The feed-dog 65 is actuated in the usual manner, disclosed for example in the U. S. Patent No. 1,429,399, referred to, and works in the feed-dog slot 65 in the work-supporting plate 51.

Having thus set forth the nature of the invention, what I claim herein is:-

1. A sewing machine having, in combination, a work-supporting plate, reciprocatory hook and eye-pointed needles mounted below said worksupporting plate, loopers cooperating with said needles above said work-supporting plate, a vertically movable slide-frame carrying said loopers, means for reciprocating said needles, means connected to said slide-frame to control the amplitude of needle-reciprocation, a relatively strong spring connected to bias said slide-frame downwardly,

an adjustable stop to determine the working r elevation of said slide-frame, a feed-dog, a presser-foot, a presser-bar carrying said presserfoot and having a limited vertical movement unaccompanied by movement of'said slide-frame, and a relatively Weak spring connected to bias said presser-bar downwardly independently of said slide-frame.

2. A sewing machine having a frame formed with a bed and an overhanging bracket-arm terminating at its free end in a head, a work-supporting plate, reciprocatory hook and eye-pointed needles mounted below said work-supporting plate, loopers cooperating with said needles above said work-supporting plate, a vertically movable slide-frame mounted in said head and carrying said loopers, means for reciprocating said needles, means connected to said slide-frame to control the amplitude of needle-reciprocation, a spring connected to bias said slide-frame downwardly, a manually adjustable stop disk mounted on top of said bracket-arm to turn about a vertical axis and having a spiral stop-face, an arm on said slideframe overhanging said spiral stop-face, a feeddog, and a spring-pressed presser-foot mounted independently of said slide-frame.

3. A sewing machine having a bed and an overhanging bracket-arm, a main shaft journaled in said bed and having a crank, a vertically reciprocatory needle-bar mounted in said bed, a lever connected at one end to said needle-bar, a pitman connecting the other end of said lever to said crank, a shiftable fulcrum-block for said lever, a stationary guideway for said fulcrum-block, a looper-supporting slide-frame mounted in said overhanging bracket-arm, and means connected to said slide-frame to shift said fulcrum-block in said guideway.

4. A sewing machine having a bed and an overhanging bracket-arm, a main shaft journaled in said bed and having a crank, a vertically reciprocatory needle-bar mounted in said bed, a lever connected at one end to said needle-bar, a pitman connecting the other end of said lever to said crank, a shiftable fulcrum-block for said lever, a stationary guideway for said fulcrum-block, a looper-supporting slide-frame mounted in said overhanging bracket-arm, and means connected to said slide-frame to shift said fulcrum-block in said guideway, said guideway being parallel to said lever in the down-position of said needle-bar.

5. A sewing machine having a bed and an overhanging bracket-arm, a main shaft journaled in said bed and having a crank, a vertically reciprocatory needle-bar mounted in said bed, a lever connected at one end to said needle-bar, a pitman connecting the other end of said lever to said crank, a shiftable fulcrum-block for said lever, a stationary guideway for said fulcrum-block, a looper-supporting slide-frame mounted in said overhanging bracket-arm, means connected to said slide-frame to shift said fulcrum-block in said guideway, and stationary guides at the opposite ends of said lever to confine the latter to rock in a vertical plane.

6. A sewing machine having a frame, a main shaft journaled horizontally in said frame and formed with a crank, a vertically reciprocatory needle-bar, a lever pivotally connected at one end directly to said needle-bar, a pitman connection between the other end of said lever and said crank, and a shiftable fulcrum for said lever.

RUDOLPH BECKER.

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