US3472187A

US3472187A - Sewing machine automatic work steering mechanisms

Info

Publication number: US3472187A
Application number: US691892A
Authority: US
Inventors: Ronald M Kaplan; Stanley J Ketterer
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1967-12-19
Filing date: 1967-12-19
Publication date: 1969-10-14
Anticipated expiration: 1986-10-14
Also published as: DE6811301U; GB1205290A; DE1814538A1; FR1598448A

Description

Oct. 14, 1969; R. M. KAPLAN ETAL 3,472,187

SEWING MACHINE AUTOMATIC WORK STEERING MECHANISMS Filed necfi ls 1967 2 Sheets-Shea 1 Fig.l.

20 6| INVENTORS SROFIOIU M. Kaplan And Witness 62 55 mnley J. Ketterer -fia%lind-n ATTORNEY Oct. 14, 1969 R. M. KAPLAN ETAL SEWING MACHINE AUTOMATIC WORK STEERING MECHANISMS Filed D60. 19, 1967 2 Sheets-Sheet 2 INVENTORS Ronald M. Koplan And v Stanley J Ketterer 64 BY I W 4.4; ATTORNEY United States Patent 3,472,187 SEWING MACHINE AUTOMATIC WORK STEERING MECHANISMS Ronald M. Kaplau, Cedar Grove, and Stanley J.

Ketterer, Morris Plains, N.J., assignors to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Dec. 19, 1967, Ser. No. 691,892 Int. Cl. Db 27/12 U.S. Cl. 112212 9 Claims ABSTRACT OF THE DISCLOSURE An automatic work steering mechanism for a sewing machine is disclosed including means connected to a servomechanism for sensing the edge of work piece on a work supporting surface of a sewing machine to signal the servomechanism when the edge of the work piece deviates from a predetermined line so that the servomechanism can operate means for moving the axis of a feed wheel to steer the work back into the line.

BACKGROUND OF THE INVENTION Field of the invention The invention relates to sewing machine work steering mechanisms.

Description of the prior art In many kinds of sewing operations, it is diflicult to maintain a uniform margin between a line of stitches in work and the edge of the work. Maintaining a uniform margin is especially diflicult in post type sewing machines used for leather sewing because of the characteristics of the work and the small area of work supporting surface in the Vicinity of the stitching point. Former work steering mechanisms have often not been sensitive enough, and have been expensive employing complicated mechanical mechanisms and photoelectric sensing devices.

SUMMARY OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a rear elevational view of a sewing machine incorporating the improved automatic work steering mechanism of the invention;

FIG. 2 is an enlarged detail view of the stitching area of the sewing machine of FIG. 1;

FIG. 3 is a head end elevational view partly in section of the stitching area of FIG. 2; and

FIG. 4 is a cross sectional view taken substantially along the line 44 in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawings, in FIG. 1 the improved automatic work steering mechanism of the invention is shown embodied in a sewing machine having a frame including a base 11, a post 12 rising from one end of the base with a work supporting surface 13 on the top of the post, a standard 14 rising from the other end of the base,

a bracket arm 15 at the topof the standard overhanging the base, and a sewing head 16 on the free end of the bracket arm above the work supporting surface of the post. As shown in FIG. '2, a conventional needle bar 17 is mounted in the sewing head for endwise reciprocation. A needle 18 is connected to the end of the needle bar to form stitches 19 in work piece 20 on the work supporting surface of the post.

Also mounted in the sewing head is a presser bar 21. As shown in FIG. 3, the presser bar has a coaxial bore 22 which houses a compression coil spring 23 and encompasses the lower extremity of a rod 24 mounted in the sewing head. The compression coil spring is sandwiched between the end of the rod and the bottom of the bore to bias the presser bar downwardly. An arcuate segment 25 is formed at the bottom of the presser bar, and an arcuate slideway 26 is formed in the arcuate segment. The arcuate slideway has an interior portion 27, and a communicating exterior portion 28 formed by two opposed ledges 29 at the bottom of the arcuate segment. The interior portion of the arcuate slideway is wider than the exterior portion giving the arcuate slideway an overall T-shaped cross section.

Mounted in the arcuate slideway at the bottom of the presser bar is an arcuate slide block 30. The arcuate slide block has a head portion 31 and a neck portion 32 giving it a T-shaped cross section complementary to the T-shaped cross section of the arcuate slideway. The head portion of the arcuate slide block seats in the interior portion of the arcuate slideway and the neck portion seats in the exterior portion of the arcuate slideway. The neck portion of the arcuate slide block rises from the top of a block 33 which has a lateral arm 34. The lateral arm has a spherical bearing 35 formed at an intermediate portion and a head 36 on the free end. A downwardly extending rod 37 having a coaxial bore 38 is mounted in a bore 39 in the block by a setscrew 40, and a downwardly extending medial boss 41 having a semicircular cross section is formed on the bottom of the block.

Mounted on the rod which extends downwardly from the block is a collar 42. The collar is connected to the downwardly extending rod by a setscrew 43 and has a groove 44 formed in the top with an inverse trapezoidal cross section mating with the boss 41 on the bottom of the block. A lateral flange 45 extends from the bottom of the collar. Also mounted on the rod is a second collar 46. The second collar also has a lateral flange 47 extending from the bottom and in the same direction as the lateral flange on the first collar. In addition, the second collar has a counterbore 48 in the bottom which houses a compression coil spring 49. The compression coil spring bears againsta flange 50 on the bottom of a pin 51 which is mounted 1n the bore 38 in the rod by a setscrew 52 to bias the second collar upwardly. I

Connected to the second collar by a screw 53 15 an extension 54 of a bracket 55. The extension is sandwiched between the

flanges

45 and 47 of the two collars. The flanges prevent pivotal movement of the bracket about the screw 53, and the compression coil spring 49 biases the extension against the uppermost flange via the lowermost flange. A shaft 56 in the form of a screw having a head 57 is connected to the bracket by two

nuts

58 and 59 with the axis of the shaft canted. A pulley 60 and a feed wheel 61 are freely mounted on the shaft, the feed wheel being integral with the pulley. The feed wheel has a knurled circumferential surface 6 2 for feeding the work piece on the work supporting surface of the post. Rotation is imparted to the feed wheel by a belt 63 which engages the pulley. The other end of the belt engages means in the sewing head which are not shown. Reference may be had to the United States Patent No. 2,678,010, May 1], 1954, for a more detailed disclosure of this feed Wheel drive. The bracket is stabilized by a rod 64 extending upwardly from the bracket to the means in the sewing head.

In order to sense the edge of the work; a sensing foot 65 having a toe 66, a heel 67, and an upwardly extending leg 68 is connected to a depending lever 69 on a bracket 70 connected to the sewing head. The toe of the sensing foot contacts the edge of the work. The sensing foot is pivotally connected to the depending lever by a pivot screw 71 which extends through a longitudinal clearance slot 72 in the upwardly extending leg. The depending lever has an alternative hole 73 for the pivot screw 71 for adjustment purposes. The longitudinal slot in the upwardly extending leg enables the sensing foot to be manually lifted off of the work supporting surface of the post. The depending lever is connected to the bracket by a screw 74, and the bracket is connected to the sewing head by two screws 75 of which one is shown in FIG. 2. The depending lever is sandwiched between a stop 76 on a plate 77 on the bottom of the bracket and the free arm of a lever 78 connected to the bracket by 'a screw 79. The stop and the lever provide an adjustment feature for the lateral position of the toe of the sensing foot on the work supporting surface of the post by fixing the angular orientation of the depending lever about its mounting screw 74.

Mounted on the bracket 70 is a controlled potentiometer 80 having a shaft 81. A crank arm 82 is clamped to the end of the shaft by a screw 83. The crank arm is biased in a clockwise direction by a torsion spring 84 mounted on the shaft. A link 85 having a longitudinal clearance slot 86 is pivotally connected to the free end of the crank arm by a pivot screw 87, and a second link 88 is pivotally connected to the heel of the sensing foot by a pivot screw 89. The two links are linearly connected by two

screws

90 and 91 which extend through the longitudinal clearance slot in the first link. The two screws keep the two links in line, and the longitudinal slot 86 in conjunction with the longitudinal slot 72 in the upwardly extending leg enable the sensing foot to be manually lifted off of the work supporting surface of the post. The torsion spring 84 on the shaft of the potentiometer biases the toe of the sensing foot against the edge of the work.

The controlled potentiometer is connected to an amplifier 92 by an electrical cord 93, and the amplifier in turn is connected to a servomechanism in the form of a servomotor 94 by an electrical cord 95. The amplifier has a power cord 96 for connection to a conventional electric outlet which is not shown. The servomotor has a rotor shaft 97 and is mounted on a bracket 98 which is connected to the standard of the sewing machine by two screws 99 with the rotor shaft in a substantially vertical position. A crank arm 100 is clamped on the end of the rotor shaft by a screw 101, and a connecting rod 102 is pivotally connected to the free end of the crank arm by a pivot screw 103. The other end of the connecting rod has a strap 104 which embraces the spherical bearing 35 on the arm extending laterally from the block which is connected to the bottom of the presser bar.

In operation, the feed wheel 61 feeds the work 20 across the work supporting surface of the post while the needle tforms stitches 19 in the work. The toe 66 of the sensing foot 65 is biased against the edge of the work by the torsion spring 84 on the shaft of the controlled potentiometer 80. When the edge of the work moves away from the toe of the sensing foot thus shortening the margin between the line of stitches and the edge of the work, the toe of the sensing foot continues to contact the edge of the work because of the action of the torsion spring. In continuing to contact the edge of the work as the edge of the work moves away from the toe of the sensing foot, the sensing foot causes the crank arm 82 of the controlled potentiometer to turn through movement of the two

links

88 and 85 connected between the sensing foot and the crank arm. Turning of the crank arm causes the controlled potentiometer to send an electrical signal to the servomotor 94 through the amplifier 92. The signal causes the servomotor to turn its crank arm 99 to pull the connecting rod 102 towards the standard end of the sewing machine. Rearward movement of the connecting rod causes the arcuate slide block 30 to slide in the arcuate slideway 26 in the bottom of the presser bar to turn the feed wheel 61 to the right as viewed from the front of the sewing machine. When the feed wheel is turned to the right, it feeds the work so that the edge of the work moves back towards the toe of the sensing foot to restore equilibrium with the edge of the work on a predetermined line as set by the initial position of the toe of the sensing foot. When the equilibrium position is reached, the controlled potentiometer causes the servomotor 94 to return the feed wheel 61 to its normal straightened position. It must be appreciated that the automatic work steering mechanism is very sensitive and that the edge of the work can never deviate very far from the predetermined line. The angular orientation of the depending lever 69 on the bracket 70 connected to the sewing head sets the predetermined line represented by the toe 66 of the sensing foot. The angular orientation of the depending lever can be adjusted by the stop 76 and the lever 78 on the bracket 70 to adjust the predetermined line. The

longitudinal slots

72 and 86 in the upwardly extending leg 68 of the sensing foot and the link enable the sensing foot to be manually lifted off of the work supporting surface 13 of the post.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made by way of example and that numerous changes in the details of construction and the combination and arrangement of parts can be resorted to without departing from the spirit and the scope of the invention.

Having thus set forth the nature of this invention, what is claimed herein is:

1. An improved automatic work steering mechanism for a sewing machine having a frame, a work supporting surface on the frame for a work piece, means mounted in the frame for forming stitches in the work piece, work feeding means including a feed wheel, means for mounting the wheel on the frame for hearing against the work piece, said mounting means including means permitting the axis of said feed wheel to be moved while retaining its relationship to the plane of said work supporting surface, and means for imparting rotation to the feed wheel to move the work piece across the work supporting surface of the sewing machine, said improved automatic work steering mechanism comprising a servomechanism, means connecting the servomechanism to said feed wheel mounting means for moving the axis of the feed wheel, and means connected to the servomechanism for sensing the edge of the work piece to signal the servomechanism when the edge of the work piece deviates from a predetermined line of feed so that the servomechanism can operate the means for moving the aXis of the feed wheel to feed the work piece back onto the line of feed.

2. The improved automatic work steering mechanism of claim 1 in which the means for mounting the feed wheel in the frame is a presser bar and there is a pivotal connection between the feed wheel and the presser bar for moving the axis of the feed wheel.

3. The improved automatic work steering mechanism of claim 2 in which the pivotal connection between the feed wheel and the presser bar is a substantially horizontal arcuate slideway and slide block.

4. The improved automatic work steering mechanism of claim 1 in which the means for sensing the edge of the work piece includes means connected to the servomechanism for signaling operation of the servomechanism, a sensing foot for contacting the edge of the work piece,

and means for connecting the sensing foot to the means for signaling operation of the servomechanism.

5. The improved automatic work steering mechanism of claim 4 in which the means for signaling operation of the servomechanism includes an amplifier connected to the servomechanism and a controlled potentiometer connected between the amplifier and the means for connecting the sensing foot to the means for signaling operation of the servomechanism.

6. The improved automatic work steering mechanism of claim 5 in which the means for connecting the sensing foot to the means for signaling operation of the servomechanism includes a crank arm on the controlled potentiometer and link means between the crank arm and the sensing foot.

7. The improved automatic work steering mechanism of claim 6 in which the link means includes sliding means so that the sensing foot can be moved away from the work supporting surface of the frame.

8. The improved automatic work steering mechanism of claim 7 which includes means for biasing the sensing foot against the edge of the work piece.

References Cited UNITED STATES PATENTS 2,678,010 5/1954 Pinkross 112--214 2,979,745 4/1961 Schaefer et a1 69-l6 X 2,970,557 2/1961 Schwab et al. 112210 3,034,781 5/1962 Touchman et al. 112214 3,080,836 3/ 196 3 Clemens et a1.

3,417,718 12/1968 Anderson 112-203 ALFRED R. GUEST,

US. Cl. X.R.

Primary Examiner