US3468271A - Sewing machines - Google Patents

Description

D. JOHNSON SEWING MACHINES Sept. 23, 1969 6 Sheets-Sheet 1 Filed Aug. 30. 1967 4 W0 A n/say mvemoa;

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INVENTOR:

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Unite States Patent 3,468,271 SEWING MACHINES David Johnson, Ramsbottom, via Bury, England, assignor to William Birch (Engineers) Limited Filed Aug. 30, 1967, Ser. No. 664,317 Claims priority, application Great Britain, Sept. 2, 1966, 39,237 6 6 Int. Cl. Db 1/10, 23/00, 57/32 US. Cl. 112199 9 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION The invention relates to sewing machines for use in joining together lengths of material, for example cloth or carpet material at their edges. Such machines are sometimes used, for example, to join lengths of material end to end for processing after which the stitching is removed.

Sewing machines for this purpose are already known in which a needle reciprocates up and down through a needle plate adjacent a material feed mechanism and a looper reciprocates back-and-forth alternately above and below the needle plate on which the material to be sewn is supported. The looper gathers thread extending between the eye of the needle and the material draws it out into a loop on its backward movement and then casts off the loop onto the needle plate. Each loop is drawn through the preceding loop by the looper.

Prior art machines of this kind have sometimes been limited as they do not sew far enough into the end of each piece of cloth and also as to the thickness of the material they can sew and have not been sufficiently robust. A difiicult problem is in fact encountered in mounting and driving the looper in such a manner that it can execute backward-and-forward reciprocating movements and at the same time is moved up and down so that in alternate forward movements it is carried above and below the needle plate.

Thus, an object of the present invention is to provide a sewing machine of this kind which is capable of sewing thick material, for example carpeting up to say inch thick including the pile (1 /2 inches of material to be sewn), and which can be used on hard or loosely woven materials.

A further object is to provide a robust machine in which the looper is accurately and strongly mounted in a frame pivotally mounted in a frame of the sewing machine.

A still further object is to provide a needle plate for cooperation with the needle and looper of such a sewing machine facilitating production of the stitches.

SUMMARY OF THE INVENTION The invention provides in a sewing machine of the present kind a looper mounted for reciprocation in a looper frame pivotally mounted in a frame of the sewing machine and driven with a rotary oscillatory motion to direct the looper so that in its backward and forward oscillations it is carried alternately above and below the needle plate.

The invention also provides in a machine as defined in the preceding paragraph a needle plate having on the side nearer the looper a stepped and inclined edge at the place where the stitches are formed such that the plate narrows in the direction of movement of the material being sewn.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings is shown a preferred embodiment of a sewing machine according to the invention.

In the drawings:

FIG. 1 is a perspective view of part of a sewing machine according to the invention;

FIG. 2 is a plan of the sewing machine of FIG. 1;

FIG. 3 is a cross-section in a vertical plane of the sewing machine of FIG. 1;

FIG. 4 is a front elevation of the sewing machine of FIG. 1;

FIG. 5 is a view from above of part of the mechanism of the sewing machine of FIG. 1;

FIG. 6 is a plan of the needle plate of the sewing machine of FIG. 1;

FIG. 7 is a side view of the needle plate;

FIG. 8 is a view of two pieces of fabric stitched together by the sewing machine of FIG. 1; and

FIG. 9 is a vie-w of a calm-track in the sewing machine of FIG. 1 taken on the line AA in FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT The sewing machine shown in the drawings comprises a main drive shaft 10 (FIGS. 2 and 3) mounted in a frame 11 by means of needle bearing 12 and 13 and by means of a ball bearing 14. A driving pulley 15 fixed on the shaft 10 is driven by an electric motor -(not shown) by means of a belt (not shown).

A ribbed pulley 16 is fixed on the shaft 10 and carries a ribbed belt 17 of rubberiscd fabric which is also carried on a ribbed pulley 18 fixed on a needle drive shaft 19 for the machine. The needle drive shaft 19 is mounted in the frame 11 by means of ball bearings 22 and 23 and has fixed on one end of it a hand wheel enabling the machine to be turned by hand.

On one end of the needle drive shaft 19 is fixed a disc 25 carrying a slide block 26 which is engaged in a slideway 27 fixed to a needle bar 28. The needle bar is mounted for vertical reciprocating motion in parts 29 and 30 of the frame 11 and carries on its lower end a needle 33 for the machine. When the machine is in use and the disc 25 is rotating, the needle bar 28 and thus the needle 33 are carried up and down by the slide block 26 engaged in the slideway 27.

Thread for the needle 33 is carried on a bobbin (not shown) mounted on a rod 31 on the top of the frame 11 and passes through a tensioning device before reaching the eye of the needle.

A cutter for trimming the edges of fabrics fed into the machine is driven as follows from the needle drive shaft 19. A spur gear wheel 34 is fixed on the shaft 19 and meshes with a further spur gear wheel 35 fixed on a shaft 36 parallel to and adjacent the shaft 19. The shaft 36 is carried in parts 37 and 38 of the frame 11. A ribbed pulley 42 is fixed on the shaft 36 and carries a ribbed belt 43 like the belt 17 which is also carried on a ribbed pulley 44 fixed on a cutter drive shaft 45. The cutter drive shaft is mounted in parts 46 and 47 of a sub-frame 48 adjustably mounted on the frame 11.

The cutter comprises a rotary blade 49 fixed on one end of the shaft and a stationary blade 50 slightly inclined with respect to the rotary blade.

The sub-frame 48 carrying the cutter is clamped to the frame 11 by means of a bolt 53 having a handle 54. On

releasing the bolt 53 the position of the cutter can be adjusted so that more, or less, of the edges of the fabrics fed into the machine is cut off.

The material is fed into and through the machine by means of a spiked wheel 55 driven by means of a ratchet and pawl (not shown) from the main drive shaft 10. The intermittent motion of the spiked wheel is phased to allow the material to remain stationary whilst the needle 33 is engaged in the material and movement of the material takes place whilst the needle is out of the fabric.

A press or foot 56 holds the material down on the spiked wheel and is spring-mounted on a rod 57 mounted on the part 29 of the frame 11 and in a guide 58.

A needle plate 59 is mounted adjacent the spiked wheel 55, part of the needle plate being below the presser foot. As shown in FIG. 7, the needle plate is curved to follow the periphery of the spiked wheel 55. It is pierced by two apertures 62 to accommodate bolts for securing it to the machine and by a right angle slot 63 which allows the needle 33 to travel through the plate and enables the stitches formed by the machine (which are formed on the plate) to escape from the plate.

The edge 64 of the needle plate 59 is located immediately adjacent the spiked wheel 55 and this edge is straight. The opposite edge 65 of the needle plate which plays a part in forming the stitches has a straight portion 66 parallel to the edge 64 a stepped portion 67 and an inclined portion 68.

-In the present embodiment, the height of the stopped portion 67 is A inch and the width of the needle plate 59 from the edge 64 to the bottom of the step is 1 inches. It is arranged that the loops of the stitches are formed on the needle plate at the top of the stopped portion 67. The stitches then quickly travel down the stepped portion as the material is moved forward and then continues to move away down the inclined portion 68 of the needle plate. A build-up of stitches is thus prevented at the stitching point. This is particularly important to enable the machine to chain off on completion of a seam and to enable the sewing to be cut and locked to prevent unravelling.

The mounting of the looper which pulls the thread from the needle into loops will now be described.

The looper 69 having a hinged latch 81 is carried on the end of a looper bar 70 mounted for reciprocating movement in a rectangular frame 71 made of magnesium alloy. It is important for the successful operation of the machine that the frame 71 shall be accurately located and the frame must be capable of oscillatory motion to carry the looper above and below the needle plate 59 for alternate forward reciprocating movements of the looper. As shown in FIG. 5, the looper frame 71 is mounted at one end on a stud 72 screwed into the frame 11. The frame 71 is journalled on the stud 72 by means of a ball bearing 73, the outer race of which is securely held in a housing 74 fixed to the frame 71 and the inner race 75 of which is engaged by a lock nut 76 on the end of the stud.

The ball bearing 73 thus acts as a trust bearing and accurately located the looper frame 71 preventing unwanted side-to-side movement of the frame along the axis on which it is journalled.

At the other end, the looper frame 71 is journalled on a shaft 77 which is mounted in the frame 11 by means of two ball bearings 78 and 79 and a needle bearing 80. The frame 71 is journalled on the shaft 77 by means of a needle bearing 83.

The shaft 77 has fixed on it, one part 84 of a spiral gear the other part 85 of which is fixed on the main drive shaft 10. The spiral gear is arranged to give a 2:1 step-up in speed from the shaft to the shaft 77.

On the end of the shaft 77 within the frame 71 is fixed a disc 86 carrying a slide block 87 engaged in a slideway 88 fixed to the looper bar 70. Thus, when the shaft 77 is turned and with it the disc 86, the looper bar 70 and 4 the looper 69 are caused to effect a reciprocating motion backwards and forwards in relation to the needle 33 located at the front of the machine.

The oscillatory movement of the looper frame 71 and the stud 72 and the shaft 77 is independent of the rotation of the shaft 77 since the frame 71 is freely journalled on the shaft 77 by means of the needle bearing 83. This oscillatory motion is effected by means of a cam track 89 (FIG. 9) formed in a cam housing 90 fixed on the drive shaft 10.

A ball 93 carried on a stud 94 fixed to a projection 95 with the looper frame 71 is engaged in the cam track 89 and is moved up and down as the cam housing 90 rotates with the drive shaft 10.

The cam track 89 is so shaped that the looper has a dwell in the position where it is downwardly tilted towards the front of the machine and a dwell in the position where it is upwardly tilted towards the front of the machine. In the addition, the cam track is shaped to bring about rapid movement of the looper frame between the dwell positions.

The motion of the looper frame 71 is so phased with the motion of the looper bar 70 and looper 69 that forward movement of the looper bar occurs when the looper frame is in its downwardly tilted dwell position and when the looper frame is in its upwardly tilted dwell position. The 2:1 step-up ratio of the spiral gear 84, 85 provides the correct speed ratio between the shaft 10 and the shaft 77 to enable this to be achieved. Forward movement of the looper bar when the looper frame 71 is in the downwardly tilted position carries the looper 69 beneath the needle plate 50 and forward movement of the looper bar when the looper frame 71 is in the upwardly tilted position carries the looper 69 above the needle plate 50.

The sewing machine operates as follows. Two pieces of material to be joined are placed one on top of the other with edges adjacent and parallel and they are fed into the machine with their parallel edges parallel to the plane of the spiked Wheel 55 and so that they pass between the cutter blades 49 and 50. The cutter trims Off the edges of the pieces of fabric and the pieces pass on and are impaled on the spikes of the wheel 55 which feeds the pieces under the needle 33 by virtue of its intermittent movement. The pieces of material pass beneath the presser foot 56 which holds them down allowing the needle to be withdrawn from them.

When the needle 33 pierces the pieces of material it carries the thread through the pieces with it and on beginning its upward movement causes the thread to pucker and form a loop through which the looper passes. On the return movement of the looper, the thread is caught in the latch on the looper and is pulled back in a loop. When the looper moves forward again to pass this time above the needle plate the loop of thread moves out of the latch down the shank of the looper. On moving forward above the needle plate, the looper traps in its latch thread extending from the pieces of material to the needle and on its return movement with this thread in its latch pulls this new loop of thread through the previous loop which is cast off onto the needle plate. As the looper moves forward again to pick up thread from below the needle plate, the new loop thread rides up its shank and the next thread taken by the looper from below the needle plate is pulled through this loop and so on.

When the pieces of material are opened out the appearance of the resulting stitches is as shown in FIG. 8. The pieces of fabric are shown butt-jointed in FIG. 8 but by cutting off less of the edges of the pieces by adjusting the position of the cutter the pieces can be arranged to overlap when they are opened out. Alternatively, by cutting off more fabric the pieces can be left with a gap between them.

If the edges of the pieces of material are reasonably straight before being fed to the machine it is enough to provide a guide in the machine for locating the pieces accurately with respect to the needle and spiked wheel. The cutter can then be replaced by this guide.

It is important in this machine to maintain accurate timing between the looper movemements and the needle movements and to achieve this a positive drive between the main drive shaft and the shaft driving the looper and between the main drive shaft and the needle drive shaft is desirable. The drive by means of ribbed belts and pulleys described above is advantageous from this point, of view.

One advantage of the looper mounting and drive described above is the good height of lift which can be imparted to the looper.

In the present embodiment the looper lifts approximately 1 /2 inches above the needle plate allowing fabrics with a combined thickness of some 1% inches to be sewn comfortably.

Another advantage of the present looper mounting is the long length of travel which can be imparted to the looper. The long length of travel gives a good bite into the material being stitched, in the embodiment described above up to 1 in., and this is of particular advantage when sewing loosely woven materials.

The needle of the machine need not be operated by the drive described. For example, a cam-lever drive for the needle can be provided.

I claim:

1. In a sewing machine for joining together lengths of material in which machine a needle reciprocates up a d down through a needle plate adjacent a material feed mechanism and a looper reciprocates back and forth alternately above and below the needle plate and gathers thread from the needle, drawing the thread into loops and casting them off onto the needle plate, each loop being drawn through the preceding loop, the improvement comprising:

(a) a frame of the sewing machine,

(b) a looper frame mounting the looper for backwards and forwards reciprocating movement parallel to the plane of the looper frame and relative to said looper frame and said needle plate, said looper frame being pivotally mounted in said sewing machine frame spaced from and to the side of said needle plate in a plane substantially aligned with said needle plate,

(c) drive means connected to said looper frame to drive same with a rotational oscillating motion about its pivot axis to direct the looper above and below the needle plate in its backward and forward movement and cam means engaging said looper frame for directing said looper frame and said looper in their reciprocating upward and downward movements.

2. A sewing machine according to claim 1, wherein said looper frame is rectangular and is pivotally mounted in said sewing machine frame for rotational reciprocating motion about an axis through the looper frame parallel to two opposite sides thereof and perpendicular to the axis of the looper, said axis of said looper being parallel to said two opposite sides of said looper frame being perpendicular to said axis of rotational reciprocating motion.

3. A sewing machine according to claim 1, further comprising at least one thrust bearing supporting said looper frame to accurately locate same on its pivot side.

4. A sewing machine according to claim 1, further comprising a ball bearing having two races, one of said races being secured to the looper frame and one to said sewing machine frame whereby said ball bearing serves as a thrust bearing to locate to said looper frame accurately along its pivot axis.

5. A sewing machine according to claim 4, wherein said looper frame is supported at one side by said ball caring, the machine further comprising a shaft rotatably mounted in said frame of the sewing machine, said shaft extending into said looper frame through an aperture in the side thereof remote from and concentrically aligned with said roller bearing and supporting said frame, said shaft also being connected to Said looper to cause reciprocating motion thereof when the shaft is rotated and the machine further comprising drive means connected to said shaft to rotate same.

6. A sewing machine according to claim 5, further comprising an arm member secured to said shaft within the looper frame, a slide block carried on said arm member, and a slideaway member secured to the looper and receiving said slide block whereby said shaft is connected to the looper to effect reciprocating motion thereof.

7. A sewing machine according to claim 1, further comprising:

(a) an arm member projecting from the looper frame,

(b) a slide carried on said arm,

(c) a disc having a cam track formed therein, said cam track receiving said slide,

((1) drive means for rotating said disc and effecting rotational oscillatory motion of said looper frame.

8. A sewing machine according to claim 7, further comprising:

(a) a drive motion common to the driven parts of the machine,

(b) positive drive means connecting said motor to the looper frame drive, the looper drive, and the needle drive to move said parts in synchronism.

9. A sewing machine according to claim 1, wherein said needle plate is formed with a stepped and inclined edge on the side nearer the looper at the place Where the stitches are formed, said plate narrowing for a portion of the distance of movement of the material being sewn to form a substantially L-shaped channel having one leg extending in the opposite direction from which said plate narrows.

References Cited UNITED STATES PATENTS 11,284 7/1854 Leighton 1l2 199 644,174 2/ 1900 Howe 112-7 771,793 10/1904 Connan 1127 2,685,265 8/1954 Spohr 112.-169

ALFRED R. GUEST, Primary Examiner US. Cl. X.R. 112-7

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