US2311194A - Needle-bar vibrating mechanism - Google Patents

Description

Feb. 16, 1943. A. R. WOOD 2,311,194

' NEEDLE-BAR VIBRATING MECHANISM Filed July 28, 1941- 3 Sheets-Sheet 1 Aifred Mod Feb. 16, 1943. A. R. W000 NEEDLE-BAR VIBRATING MECHANISM 3 Sheets-Sheet 2 Filed July 28, 1941 w a 4 4m? gr WW 5 Alfred IVbozi Feb.'16, 1943. R, w o 2,311,194

- NEEDLE-BAR vmmwme MECHANISM Filed July 28, 1941 5 Sheets-She et s I 1 fill/radii. "420d Patented Feblfi, 1943 2,311,194 7 NEEDLE-BAR VIBRATING MECHANISM Alfred R. Wood, Bridgeport, Conn, assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application July 28, 1941, Serial No. 404,283

7 Claims.

This invention relates to sewing machines and. more particularly, to the needle-bar vibrating mechanism of sewing machines adapted to perform a predetermined sewing operation and then automatically come to rest.

The invention has for its primary object to provide improved mechanism for automatically controlling the amplitude of needle-vibration at predetermined periods in the stitching cycle.

Another object of the present invention is the provision of a needle-vibration control device of a type adapted for convenient attachment upon existing assembled machines and designed particularly for automatically decreasing the amplitude of vibration of the needle at the beginning and ending of the stitching cycle to produce groups of tying stitches effective for preventing raveling of the tack.

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 embodiment 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.

In the accompanying drawings, Fig. 1 is a side elevation, partly in section, of a Singer class 79 tacking machine embodying the present invention.

Fig. 2 is a top plan view of the bracket-arm of the machine.

Fig. 3 is a reverse side elevation of the gearing shown in Fig. 1. V

Fig. 4 is a top plan view, partly in section, of the gearing shown in Fig. 3.

Fig. 5 represents an enlarged vertical sectional view taken longitudinally of the bracketarm, illustrating the details of the head of the shaft carrying the needle-bar-vibrating crankmechanism, with the crank-pin of the head at one extreme position of adjustment.

Fig. 6 is a sectional view similar to Fig. 5, but with the crank-pin at the other extreme position of adjustment.

Fig. '7 is a disassembled perspective View of the parts shown in Figs. 5 and 6.

Fig. 8 is an enlarged top plan of the improved cam attachment adapted for controlling the amplitude of needle-vibration, showing the method of securing the same upon one of the existing gears in the sewing machine.

Fig. 9 is a vertical sectional view taken through screw 35.

the cam attachment and the gear upon which the sameis adapted to be fastened.

Fig. 10 is an enlarged view illustrating the completed tack effected by a sewing machine equipped with the present invention.

The invention is designed more particularly for embodiment in the needle-bar vibrating crank-mechanism of a sewing machine, such as disclosed in the patent to E. B. Allen, No. 1,864,165, of June 21, 1932. The machine has the usual bed I, standard 2, overhanging arm 3 and head 4. The stitch-forming mechanism comprises the reciprocating and laterally vibrating needle-bar 5 carrying the eye-pointed threaded needle 6. The needleebar 5 is journaled for endwise reciprocation in the swinging gate 1 which is mounted on pivot-pins 8 and derives its vibratory movement from the main sewing shaft 9. The gate 1 is connected by means of a link Iii to a slotted arm II which is fulcrumed at !2 on the bracket-arm 3 and is connected by a link I3 to a crank-pin l4 fixed to a radially movable slide-plate carried by the rotary guide-head I 6 formed at the upper end of a hollow shaft l1 journaled vertically in the bracketarm 3. The guide-head [6 receives step-'by-step rotae tional impulses through a train of gears l8 from the intermediate feed-actuating shaft. [9 which carries a star-wheel 2|] with which mesh the pins 2| carried by the hub of a bevel-gear 22 mounted on the bearing pin 23 and driven by a bevelpinion 24 on the main sewing shaft 9. The gear 22 is driven at half the speed of the shaft 9 and the gearing I8 is. of such ratio that the guide-head It isgiven a half-rotation for each impulse of the star-wheel received from one of the pins 2|. The needle-bar 5. is reciprocated by means of the usual crank 25 and link-connection 26 with the main sewing shaft 9.

The hollow shaft 1 I has endwise slidably fitted therein a vertical rod 21 having at its upper end an inclined portion 28 having fiat, parallel and inclined, edge-faces 29 in sliding engagement with the similarly spaced parallel and inclined faces 3i: provided by plates 3| 32 mounted atthe under side of the slide-plate IS. The plate 3| is screwed fast in a fixed position to the slideplate. The plate 32 is secured to the slideeplate by screws 33 which pass through enlarged holes 34 in the slide-plate [5, giving clearance for limited adjustment of the p1atef32 relative tov the plate 3| under the influence of the adjusting The adjustment is so made as to eliminate lost-motion between the inclined end 28 of the rod 21 and the plates 3i, 32, while retaining a free working fit. It will be understood that endwise movement of the rod 21 will shift the slide-plate I 5 and crank-pin [4 diametrically of the guide-head I6 and vary the operative radius of the crank-pin. The movement of the slide-plate I 5 is limited in one direction by a stop-plate 35 which is fixed to one end of the slide-plate I5 in position to engage the flat edge-portion 31 of the guide-head. The movement of the slide-plate l5 in the opposite direction is limited by a stop-screw 38 which is threaded into the guide-head l6 and held in adjusted position by the locking screw 39, see Fig. 7. The head of the stop-screw 38 is in position to be engaged by a stop-shoulder 40 on the slide-plate I5 (see Fig. '7).

The rod 2? is formed at its lower end with a neck 4| embraced by the fork 42 at one end of a pin 43 journaled in a boss 44 provided on the free end of a lever 45 fulcrumed at 45 on the standard 2. Adjustably secured to the lever 45 intermediate its ends by a screw-and-slot connection 4'! is a follower 48 having an offset lower end 49 (see Fig. 9) which engages and rides upon a needle-vibration control-cam secured to rotate with the gear-wheel 55 fixed to a vertical shaft 5| carrying the main feed-cam 52 which is connected as usual to shift the regular work-clamp 53. It will be understood that when the follower 48 rides upon the upper surface of the controlcam on the gear-wheel 50 as shown in Fig. 9, the operative radius of the crank-pin I4 is increased to a maximum with a consequent maximum amplitude of vibration of the needle. In the machine chosen to illustrate the present invention the control-cam is designed to maintain the needle vibration at maximum during a major portion of each stitching cycle and at a minimum, or substantially zero, only during the formation of a few stitches at the beginning and ending of each stitching cycle.

The needle-vibration control-cam, as used in the illustrated machine, is the essence of the present invention. As shown in Figs. 8 and 9, the control-cam comprises preferably a disk 54 formed with a horizontally disposed flange 55 providing a primary cam-section, and a centrally located hub-receiving throat 55 opening laterally into the periphery of the flange 55, whereby the control-cam can be conveniently placed upon the hub 51 of the gear-wheel 55. To rovide means for securing the control-cam in proper position upon the gear-wheel hub, the body of the disk 54 at opposite sides of the mouth of the hubreceiving throat 55 has threaded into it two setscrews 58 which, as shown in Fig. 8, are angularly arranged and are adapted at their inner ends to engage with one side of the gear-wheel hub 57. The two set-screws 58 are preferably located adjacent the opposite sides of the hub-receiving throat 56 and are spaced apart a distance greater than 180, as shown in Fig. 8, in order that they will draw and clamp the cam firmly upon the hub of the gear 51.

Formed in the upper flat surface of the flange 55 is a concentric recess 59 in which is slidably disposed for limited circular endwise adjustment a supplemental or secondary cam-section 59 adapted to be maintained in adjusted position by a securing screw 6| passing through an elongated aperture 52 in the secondary cam-section. The secondary cam-section 60 at its leading end is bent downwardly, as at 63, in order that the follower 48 when being approached by the camsection 59 will readily climb to a position on top of the cam-section. As clearly shown in Fig. 9, the lower end 49 of the follower 48 is offset outwardly in order to provide clearance for the securing screw 6 i It will be understood that when the follower 48 is riding upon the secondary camsection 55 only the inner portion of the lower end of the follower engages the cam-section, and that after the secondary cam-section travels beyond the follower the latter rides upon the narrow flat upper surface or primary cam-section of the flange 55. The follower 48 is biased into contact with the needle-vibration control-cam by a spring-wire B4 coiled about a lug 65 integral with the bracket-arm 3, one end of the springwire being anchored by a screw 65 and the other end bearing downwardly upon the boss 44 provided on the end of the lever 45.

It will be observed that the adjustable secondary cam-section '60 is provided for reducing the width of the mouth of the hub-receiving throat 56 in order that the number of tying stitches produced at the beginning and ending of the stitching cycle may be controlled. The initially large mouth of the hub-receiving throat is necessary since the needle-vibration control-cam has been designed for convenient attachment upon existing machines without the necessity of disassembling the gearing. In attaching the illustrated needle-vibration control-cam upon the gear-wheel 59, it is only required that the secondary cam-section 50 be removed from the control-cam and the set-screws 58 unscrewed. The control-cam can then be placed upon the hub of the gear-wheel 55 and when properly located the set-screws 58 are tightened. The secondary camsection 50 is then placed in position in the recess 59 and secured by the screw 6 I.

Fig. 1 discloses the machine immediately after the starting lever has been depressed and the machine has begun to perform its stitching cycle shown in Fig. 10. It will be observed that the lower end 49 of the follower 48 is disposed substantially midway between the rear edge 61 of the mouth of the control-cam 54 and the inclined leading edge 63 of the secondary camsection 60 and that it is in contact with the upper surface of the gear-wheel 50. When in this position the axis of the crank-pin I4 is in substantial alinement with the axis of the hollow shaft I 1 (Fig. 5); the amplitude of needle-vibration being at a minimum during such alined position of the crank-pin and hollow shaft. After the formation of a predetermined number of superposed stitches, which function to effectively lock the beginning end of the tack, the inclined leading edge 63 of the secondary camsection 60 engages the follower 48 and raises the lever 45 against the action of the springwire 64. The raising of the lever 45 shifts the crank-pin I4 to its position of maximum radius (Fig. 6), in which position the crank-pin l4 imparts to the needle vibrations of maximum amplitude. The follower 48 rides upon the upper surface of the control-cam during the forma tion of the body of the tack, indicated as B in Fig. 10. At the proper time in the cycle, the follower 48 drops off the rear edge 61 of the control-cam into a position controlled by the stop-plate 35. Immediately upon dropping off of the rear edge 61 the radius of operation of the crank-pin is reduced, to substantially zero, resulting in the formation of a plurality of tying st tches, indicated as T in Fig. 10, which serve to effectively prevent raveling of the completed tack. The stop-motion of the sewing machine is adjusted so that the operation of the machine is interrupted when the follower 48 is substantially midway between the rear edge 61 of the mouth of the control-cam and the inclined leading edge 63 of the secondary cam-section 60. When the machine comes to rest, the parts are so positioned as to repeat the above described stitching cycle when the starting lever is depressed.

It will be understood that the location of the inclined leading edge 63 and the rear edge 61 relative to the follower 48 determines the number of tying stitches produced at the beginning and ending of the tack and that by suitably adjusting these edges relative to the follower 48 and relative to each other more or less tying stitches may be formed at the beginning or ending of the tack. Also the number of the tying stitches at the beginning and ending of the tack may be the same or different. It will be obvious that by shifting the inclined leading edge 63 so that it substantially touches the rear edge 61, no tying stitches will be made.

While the drawings illustrate a control-cam in which the narrow flat upper surface of the flange 55 on which rides the follower 48 is, throughout its length, at a uniform height above the upper surface of the gear-wheel 50, it will be understood that the narrow surface may be cut so that it is at a varying height above the upper surface of the gear-wheel, in which case vibrations of different amplitude will be imparted to the needle. Such a control-cam could be employed for embroidery work in which case the stitch-design required would dictate the shape of the narrow upper surface of the flange 55.

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

l. A unitary needle-vibration control-cam adapted for convenient attachment upon a sewing machine having a vibratory needle and a cam-actuated mechanism for controlling the amplitude of vibration of said needle, comprising, a body-portion having a flange and a support-receiving throat formed with a mouth opening into the periphery of said flange, a primary cam-section on said flange, and a secondary cam-section having a portion thereof disposed in the mouth of said throat so as to extend the active portion of the control-cam to effect the production of a predetermined pattern of stitches.

2. A unitary needle-vibration control-element adapted for convenient attachment upon assembled group-stitch sewing machines having a vibratory needle and a cam-actuated mechanism for controlling the amplitude of vibration of said needle, comprising, a disk-like body-portion adapted in operation to be rotated about an axis and having a lateral flange and a support-receiving throat formed with a mouth opening into the periphery of said flange, a primary cam-section on said flange, and a secondary cam-section mounted on said flange for adjustment relative to said primary cam-section about the axis of rotation of the body-portion, said secondary cam-section having a portion thereof extending into the mouth of said support-receiving throat in order to extend the active portion I of the control-element.

for controlling the amplitude of vibration of said needle, comprising, a disk-like body-portion adapted in operation to be rotated about an axis and having a lateral flange and a centrally located support-receiving throat formed with a mouth opening into the periphery of said flange,

said lateral flange being formed with a recess concentric with said support-receiving throat, a primary cam-section on said flange, a secondary cam-section mounted in said recess and having a portion thereof extending into the mouth of said support-receiving throat, and means for securing said secondary cam-section in said recess for limited adjustment relative to said primary cam-section in order to regulate the active portion of the control-element.

4. A unitary needle-vibration control-element adapted for convenient attachment upon assembled group-stitch sewing machines having a vibratory needle and a cam-actuated mechanism includin a gear having a hub for controlling the amplitude of vibration of said needle, comprising, a disk-like body-portion having a laterally extending horizontal flange and a hub-receiving throat formed with a mouth opening into the periphery of said flange, said flange being provided in its upper surface with a recess concentric with the hub-receiving throat, a primary cam-section on said flange, a secondary cam-section mounted 3 in said recess and having a portion thereof extending into the mouth of said hub-receiving throat, the portion of said secondary cam-section extending into said recess having an elongated aperture formed therein, and a screw passing through said elongated aperture and threaded into said horizontal flange for adjustably securing said secondary cam-section in operative position.

5. A unitary needle-vibration control-element adapted for convenient attachment upon assembled group-stitch sewing machines having a vibratory needle and a cam-actuated mechanism for controlling the amplitude of vibration of said needle, comprising, a disk-like body-portion having a laterally extending flange and a supportreceiving throat formed with a mouth opening into the periphery of said flange, means including a pair of screws threaded into said body-portion for securing said unitary control-element upon its supporting member, a primary cam-section on said flange, and a secondary cam-section mounted on said laterally extending flange and having one end thereof projecting into the mouth of said support-receiving throat to increase the length of the active portion of the control-element.

6. A needle-vibration control-element adapted for convenient attachment upon group-stitch sewing machines having a vibratory needle and, a cam-actuated mechanism for controlling the amplitude of vibration of said needle, comprising, a

0 disk-like body-portion having a laterally projecting flange and a support-receiving throat formed with a mouth opening into the periphery of said flange, securing means for said control-element including a pair of screws threaded into said body-portion in angular relationship and, having their inner ends extending into said supportreceiving throat and adapted to engage the control-element supporting member, a primary camsection on said flange, and a secondary camsection mounted on said laterally projecting flange and having one end thereof extending into the mouth of said support-receiving throat to increase the length of the active portion of the control- 75 element.

7. A unitary control-element adapted for con venient attachment upon assembled sewing machines, comprising, a body-portion having a laterally extending flange and a support-receiving throat formed with a mouth opening into the periphery of said flange, means including a pair of screws threaded into said body-portion for securing said control-element upon its supporting member, a primary cam-section on said flange,

a s'eeondary cam-section mounted on said laterally extending flange and having one end thereof projecting into the mouth of said support-receiving throat to increase the length of the active portionof th control-element, and means adjustably securing said secondary cam-section on said flange.

ALFRED R. WOOD.

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