US2690723A

US2690723A - Zigzag sewing mechanism of doublethread sewing machine

Info

Publication number: US2690723A
Application number: US218788A
Authority: US
Inventors: Sudo Hidenori
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-04-04
Filing date: 1951-04-02
Publication date: 1954-10-05
Anticipated expiration: 1971-10-05

Description

ZIGZAG SEWING MECHANISM OF DOUBLE-THREAD SEWING MACHINE Filed April 2, 1951 HIDENORI $5.356

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Z /M.L-w, Mama Oct. 5, 1954 HIDENORI sumo ZIGZAG SEWING MECHANISM OF DOUBLE-TX-IREAD SEWING MACHINE 4 Sheets-Sheet 2 Filed April 2, 1951 FIG. 3

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ZIC-ZAG SEWING MECHANISM OF DOUBLE-THREAD SEWING MACHINE Filed April 2, 1951 4 Sheets-Sheet s jump NM" aka 5,, E954 HiDENORl sumo ZIGZAG SEWING MECHANISM OF DOUBLE-THREAD SEWING MACHINE Filed pril 2. 1951 4 Sheets-Sheet 4 Patented Oct. 5, 1954 UNITED STATES PATENT OFFICE ZIGZAG SEWING MECHANISM OF DOUBLE- THREAD SEWING MACHINE Hidenori Sudo, Osaka, Japan Application April 2, 1951, Serial No. 218,788

Claims priority, application Japan April 4, 1950 2 Claims. 1

This invention relates to mechanism by which, in addition to the ordinary vertical motion of the needle-bar and the rotating motion of the shuttle of the ordinary straightly advancing sewing mechanism, the needle-bar is made to shift in left and right directions in the amount of the zigzag, at around the upper limit of the vertical movement of the needle-bar, for the purpose of performing zigzag sewing. At the same time the shuttle also is started to swing in the direction of the shift and in the same amount as the shift of the needle-bar. The shuttle is made to shift at will within the limit of the amount of zigzag. All this is done by manipulation of a lever. The

invention relates also to the construction of such mechanism. Its object is the provision of mechanism to be used for various types of applied sewing which combine straight-running sewing width with zigzag Width.

Fig. 1 is a front view in vertical longitudinal section of a sewing machine embodying my invention.

Fig. 2 is a plan view of some of the operating mechanism of the machine of Fig. 1.

Figs. 3 and 4 are, respectively, views from the bottom and from the front of the machine showing the principal parts of the zigzag stitch shifting mechanism.

Figs. 5 and 6 are, respectively, end elevations of the parts of Fig. 3 as seen from the left of that figure on the line a--a and from the right of that figure on the line b-b.

Fig. '7 is a series of four diagrams illustrating how the basic seams of zigzag sewing are obtained by my mechanism.

Fig. 8 is a series of perspective views coordinating the sewing movements of Fig. 7 with the mechanism of the other figures.

The zigzag sewing mechanism of the double thread sewing machine (lock stitch machine) to which this invention relates, is a novel mechanism in which, as above mentioned, the needle-bar is made to shift in left and right directions only in the amount of the zigzag, at around the upper limit of the needle-bar movement, for the purpose of performing zigzag sewing. At the same time the shuttle also is swung in the direction of the shift in the same amount as the shift of the needle-bar, and made to shift at will within the limit of the zigzag by manipulation of a shift lever. All this is in addition to the ordinary vertical movement of needle-bar and the rotating movement of shuttle of the ordinary straightly advancing sewing mechanism.

An example of the actual construction of the mechanism is given below.

Referring to the drawings, the triangular cam 28, which rotates at a reduced speed of one half through the speed-

reduction gears

46, 41 from the main shaft I, is made to slide in a groove in the forked connecting rod 29. This rod is pivoted to the pivot in the lower end of the'arm-handle 43 fitted on the basic shaft 3| to which is also affixed the shift lever 32. At the same time the arc groove .33 which is provided at the back of the forked connecting rod 29 is used to guide the slider 36. The slider is supported on one end of a connecting rod 34 by an axial pin 35. The other end of the connecting rod is linked to the arm 25 which in turn is carried by the rock shaft 9 of the shuttle l9 and the needle bar 4. Movably carried on the rock shaft 9 is a sleeve 45 for the zigzag shift lever 31. This sleeve 45 has an arm plate 38 lying parallel to the connecting rod 33. The end of the arm plate 38 is connected with the center of the connecting rod 34 by means of the connecting piece 4|. The distance between the said connection 48 on the connecting rod 36 and the connection 24 on the arm rod 25 fixed to the oscillating rock shaft 9, and the distance between the two ends 39 and 9 of thearm plate 38 are made equal in length. It is so constructed that, when the shift lever 32 is placed at central position and the center of the slider 35 of the connecting rod 34 moving in the arc groove 33 on the back side of the forked connecting rod 29 is made to agree with the pivot 30 of the forked connecting rod 29, the four following distances, namely, the distance between the said fixed pivot 30 and the basic shaft 3| of the shift lever 32, the distance between the said pivot 38 and the rotating shaft 42 of the triangular cam 28, the distance between the upper end 39 and the lower end 40 of the connecting piece 4 l, and the distance between the rock shaft 9 and the connection 24 of the arm rod 25 fastened to the oscillating rock shaft 9 are equal in length and parallel each other. Under these conditions of equality it is also true that the amount of horizontal oscillating movement of the pivot 30 of the forked connecting rod 29 is equal to the eccentric diameter of the triangular cam.

The relation between the above mentioned mechanism and the vertical movement of the needle-bar and the rotating mechanism of the shuttle I9 is as follows:

Referring to Fig. 1 and Fig. 2, the rotation of the main shaft l provides, through the needle-bar crank rod 2 and the needle-bar recess 3, the up and down movement of the needle-bar 4, and further, at the rear turns the vertical connecting rod I2 by means of gears l0 and I I, and transmits rotation to the horizontal shaft [5 by means of the gears l3 and Hi. The frame of the machine, partly in section, is shown at 5. The horizontal shaft l5 and shuttle shaft l8 are in contact with each other face to face by the semi-circular cross sections l5, 13 in the interior of the connecting rod sleeve 18. The connecting rod sleeve 16 is fastened to the horizontal shaft [5 by the push screw 11. The oscillating rock shaft 9 is vertically borne in parallel with the vertical connecting rod l2 by pivot pins 23, slightly to one side of the main shaft I. If the arm rod fastened to the oscillating shaft is operated horizontally, the connecting arm 6 of the needle-bar 4 is made to oscillate by means of the connection 24, the connecting piece 8 and the rod 1. In addition the needle-bar 4 shifts positions horizontally between 41, Am, 6r (left, middle and right) while making an up-and-down sewing movement by means of the needle-bar crank rod 2. At the same time, the arm 26 fastened to the lower end of the oscillating rock shaft 9 is moved left and right synchronously with the rod 1, and consequently, the rod 22 connected at the end of the arm 25 shifts the position of the shuttle I9, through the connecting piece 2! and sleeve 29, in exactly the same amount as the horizontal movement of the needle-bar.

The mechanism of this invention, described above, functions as follows:

As the rotating main shaft l causes the triangular cam 28 to rotate, through the 2:1 speed reduction gears 46, ll, the forked connecting rod 29 is swung right and left with the shaft 30 as the center. is connected at the pivot 30 with the arm handle 43 provided on the basic shaft 3|, it is, in principle, shifted by the shift lever 32 to the three positions of left, middle and right, with the basic shaft 31 as the supporting point. Thus the forked connecting rod 29 oscillates between these three positions.

The slider 36 pivoted to the concentric shaft of the shaft of the connecting rod 34 is fitted in with the arc groove 33 on the back side of the forked connecting rod 29. The connecting piece 8 and the rod '1 which cause the needle-bar 4 to shift horizontally are connected with the connection 24 at the other end of the connecting rod 34. The oscillating movement of the shuttle I9 is done through the oscillating rock shaft 9 from the arm 25. A freely rotatable sleeve is movably fitted at the upper portion of the said oscillating rock shaft 9. To this sleeve are fastened the zigza shifting lever 3'1 and arm plate 38 and the end of it and the middle of the connecting rod 34 are connected with each other at the shafts 39 and 4 by the connecting piece ll. Consequently, if the zigzag shifting lever 31 is shifted to the left side, the slider 36 is drawn toward the oscillating pivot 30 of the forked connecting rod 29. When the zigzag shifting lever 37 is at the extreme left 31 min. and the center 35 of the slider 36 agrees with the position of the oscillating center shaft, the forked con necting rod 29, however hard it oscillates, can never cause the connecting rod 34 to be affected. On the other hand, if the zigzag shifting lever 3! is moved to the right, the slider 36 is drawn further away from the oscillation center pivot 30, and the connecting rod 34 is started, thus enlarging the amount of the zigzag.

The above described function is illustrated in Fig. 8. Fig. 8, A shows the position when the zigzag shifting lever 31 has been shifted to the Since the forked connecting rod 29 extreme left 31 min. and consequently the slider center 35 has agreed With the center of the pivot 30, that is, with the center of rocking of the forked connecting rod 29. If the shifting lever 32 is positioned at 321*, the slider 36 and the pivot 30 are positioned at 35 min. 7- 30 in the drawing, and the needle-bar 4 and shuttle l9 run straightly along the line 1 of Fig. '7, A. Likewise, if the shift lever 32 is shifted to 32m, the slider center 35 and the pivot 30 are positioned at 35 min. m. 30m, and the end shaft 24 of the connecting rod 34 is shifted to 24m and runs straightly on the line m in Fig. 7, A. If the shift lever 32 is shifted to 321, straight running stitches are formed on the line Z of Fig. 7, A.

Fig. 8, B is the illustration of the case when the zigzag amount is increased or decreased by the operation of the zigzag changing lever 3'1 when the position shifting lever 32 is shifted to the position of 321 and the pivot 30 is at 301'. As the triangular cam 28 is rotated, the forked connecting rod 29 is oscillated, and the slider shaft 35 moves to and fro in an arc with 30m as the center, by the operation of the connecting rod 34, the arm 25 and the connecting piece ll.

Since the amount of the horizontal shift of the pivot 30 is made equal to the eccentricity of the triangular cam 28, 241' is positioned at the center of the are 337' 35 max 1". When the zigzag amount is increased with the swinging of the forked connecting rod 29, that is, when the zigzag amount changing lever 31 is shifted to the right, the slider shaft 35 starts from the swinging center pivot 30 of the forked connecting rod 29, slides along on the arc groove 33, and moving between the arcs 307', 35 max, 301- 35 max 1, detaches from 391'. The further away it moves from 301', the greater will become the swinging width. At the limit, the slider center 35 moves back and forth on the are 35 max. 7 and 35 max. 1. As the 241 is at the center of the are 302" 35 max r, the point 24 swings toward 241, with 261' always as the right extremity, in an arc with the oscillating rock shaft 9 as the center radius, and arrives at 241 when the slider shaft 35 is furthest away from 301'. Consequently the zigzag amount is the greatest at this point, and increases or decreases with the amount of shift of the zigzag amount change lever 31, thereby forming the zigzag seams, expanding toward the left (in the direction of the line 1) with the line 1" always as the right basic line, as shown in Fig. 7, B.

In a similar way, Fig. 8, C shows the case when the zigzag amount is increased and decreased by the zigzag amount changing lever 31, with the shifting lever 32 positioned at the center 32m. In this case the 24m is at the center of the arc 39m 35 max m. Seams which expand toward left Z and right 1" equally, with the expansion of the zigzag amount, are formed, with the line m always as the central basis line, as shown in Fig. 7, C.

Fig. 8, D shows the case when the zigzag amount is increased and decreased by the zigzag amount change lever 37, with the shifting lever 32 positioned at 321. In this case, the 241 comes at the center of the arc 351 35 max 1. Consequently the zigzag seams which extend toward the right (in the direction of the line 1") with the line A always as the left basis line, as shown in Fig. 7, D.

I claim:

1. A double-thread sewing machine having zigzag sewing mechanism, comprising a main drive shaft, speed reduction gears driven thereby, a shaft-mounted triangular cam driven by the speed reduction gears, a forked connecting rod oscillated by the triangular cam and having an arcuate groove therein, a slider guided by the arcuate groove in the triangular cam, a needle bar and a shuttle, in combination with a rock shaft for the shuttle and needle bar adapted to move the latter two parts laterally, an arm rod and a connecting rod connecting the slider to the rock shaft, a sleeve on the rock shaft, an arm plate on the sleeve, a link connecting the end of the arm plate to the connecting rod, the length of the arm plate and the distance on the connecting rod from the arm rod to the link being equal; said forked connecting rod being pivotally carried from a basic shaft by an arm handle and there being a zigzag control lever fitted on the arm handle: the dimensions of the parts being such that with the shift lever in central position and the slider in registry with the pivot of the forked connecting rod, the following four lengths are equal and parallel (a) from the said pivot of the forked connecting rod on the arm handle to the basic shaft, (1)) from the said pivot to the shaft carrying the triangular cam, (c) the length of the connecting link, and (d) the length of the arm rod; whereby the amount of horizontal oscillating movement of the pivot of the forked connecting rod is equal to the eccentric diameter of the triangular cam.

2. A double-thread sewing machine according to claim 1 in which there is a second lever connected to the rock shaft sleeve adapted tomove the slide and thereby to change the amount of zigzag.

References Cited in the file of this patent FOREIGN PATENTS Number Country Date 363,084 Italy Sept. 17, 19 8 694,877 Germany Aug. 9, 1940