US3490400A - Straight stitch control mechanisms for zigzag sewing machines - Google Patents

Description

Jan. 20, 1970 D, P. BUAN ET AL STRAIGHT STITCH CONTROL MECHANISMS FOR ZIGZAG SEWING MACHINES Filed NOV. 20, 1967 2 Sheets-Sheet 1 BY Augus? WiTNESS:

m mne m N w w m n T m M Jan. 20, 1970 D. P. BUAN ET AL 3,490,400

STRAIGHT STITCH CONTROL MECHANISMS FOR ZIGZAG SEWING MACHINES Filed Nov. 20, 196 2 Sheets-Sheet 2 IN VENTORS' Duniio P Buan and ugusi Mqnieim .IGML NTTQRNEY United States Patent 3,490,400 STRAIGHT STITCH CONTROL MECHANISMS FOR ZIGZAG SEWING MACHINES Danilo P. Buan, Old Bridge, and August Monteiro, Kearny,

N.J., assignors to The Singer Company, New York,

N.Y., a corporation of New Jerse Filed Nov. 20, 1967, Ser. No. 684,430 Int. Cl. D05b 3/02 US. Cl. 112158 6 Claims ABSTRACT OF THE DISCLOSURE A lever operated by means for changing the stitch width of a zigzag sewing machine serves to move connecting means to a needle bar gate out of contact with cam follower means when the means for changing the stitch width is set for zero stitch width.

BACKGROUND OF THE INVENTION The invention relates to control means for readying a zigzag sewing machine to sew straight stitches.

DESCRIPTION OF THE PRIOR ART Sewing machines which can sew a wide variety of different stitch patterns have been increasingly demanded by consumers. However, straight sitch sewing constitutes perhaps the most frequent operation performed by a sewing machine. In one type of sewing machine which can sew a wide variety of stitch patterns, a wobble plate is pivotally mounted on the end of a rod connected to a needle bar gate, and the connecting rod is spring biased against a cam follower and a fulcrum projection. The cam follower tracks a cam which is mounted on a cam shaft. Also mounted on the cam shaft is a bracket having a universal joint connection to the wobble plate. By shifting the angular position of the bracket on the cam shaft, the wobble plate can be moved relatively to the fulcrum projection and the cam follower in order to change the width of lateral movement of the needle in zigzag sewing. The extent of such lateral motion is termed stitch width. When the Wobble plate is positioned so that the fulcrum projection bears directly opposite the pivoted mount for the wobble plate, the zero stitch width will occur. It can be appreciated that for uniform straight stitch sewing to be formed relying upon such zero stitch width setting, a most precise orientation of the wobble plate is necessary. However, economically feasible machine tolerances, the tendency of parts to get out of adjustment, and normal wear of parts have militated against obtainment of this degree of precision.

SUMMARY OF THE INVENTION It is therefore a primary object of the invention to provide an improved straight stitch control mechanism for a zigzag sewing machine of the type having abutment means on connecting means to a needle bar gate spring biased against a cam follower means in which it is possible to obtain consistent uniform straight stitches.

Another object of the invention is to provide an improved straight stitch control mechanism in accordance with the foregoing object in which the abutment means on the connecting means to the needle bar gate is held out of contact with the cam follower means when the stitch width control mechanism is set for zero stitch width.

Another object of the invention is to provide an improved straight stitch control mechanism in accordance with the foregoing object in which the abutment means on the connecting means to the needle bar gate is moved out of contact with the cam follower means in response to the same operator influence by which the stitch width control mechanism is set for zero stitch width.

3,490,400 Patented Jan. 20, 1970 Other objects and a fuller understanding of the invention can be had by referring to the description and claims taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a sewing machine with the top cover removed to show the improved straight stitch control mechanism of this invention;

FIG. 2 is a front elevational view of the upper portion of the control panel on the front of the bracket arm and standard of FIG. 1;

FIG. 3 is a cross sectional view taken along the line 3--3 in FIG. 1; and

FIG. 4 is an exploded perspective view of the improved straight stitch width control mechanism of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawings, in FIG. 1 the invention is shown embodied in a sewing machine having a frame 11 of which the top of a standard 12, a bracket arm 13 extending laterally from the top of the standard, and a sewing head 14 at the free end of the bracket arm are shown. The top of the frame is covered by a top cover 15, as shown in FIG. 3. In FIG. 1, the top cover is removed to show the inside of the lbracket arm. A control panel 16 is connected to the front of the bracket arm and standard. Mounted between the bracket arm and the control panel on two bosses 17 on the bracket arm is a plate 18 which is held by screws 19 threaded one into each of the bosses. Two slotted apertures, 20 and 21, are formed in the plate in line with two slotted apertures 22 and 23, in the bracket arm and also in line with two slotted apertures 24 and 25, formed in the control panel. As shown in FIG. 2, indicia L, C and R are formed above the uppermost slotted aperture 24 in the control panel, and indicia 1 to 5 are formed above the lower-most slotted aperture 25 in the control panel. A notch 26 is formed in the upper edge of the lowermost slotted aperture 25 in the control panel beneath the indicia 1. The indicia 1 represents zero stitch width, while the indicia 5 represents maximum stitch width. The indicia L, C, and R above the uppermost slotted aperture represent left, center, and right needle positions, respectively. Mounted in the sewing head is a needle lbar gate 27, which is pivotally connected at an intermediate portion to the sewing head 14 by a hinge pin 28. A needle bar 29 is slidably mounted in the front end of the needle bar gate. Endwise reciprocating motion is imparted to the needle bar by a conventional crank mechanism indicated generally at 30. The crank mechanism is fast on an arm shaft 31 which extends longitudinally through the bracket arm 13 and is journaled in two partitions 32 and 33, one in the head end of the bracket arm and the other in the top of the standard. A hand wheel 34 is mounted on the standard end of the arm shaft. Pivotally connected to the rearmost end of the needle bar gate by a pivot screw 35 is a connecting rod 36, the free end of which extends into the bracket arm. An abutment means is carried by a connecting rod against which control impulses are directed to influence the lateral position of the needle bar. Preferably the abutment means takes the form of a wobble plate 37, which is pivotally connected to the free end of the connecting rod by a vertical hinge pin 38. Pivotally mounted in the bottom of the bracket arm in the vicinity of the wobble plate 'by a'pivot screw 39 is a bell crank 40 having two arms 41 and 42, of which one arm 41 is formed in the shape of a hook. A tension coil spring 43 is stretched between the hooked arm 41 of the bell crank and a stud 44 on the rearmost end of the needle bar gate biasing the other arm 42 of the bell crank against the 3 wobble plate 37 thus to bias the wobble plate towards the standard end of the sewing machine.

Journaled in a boss in the bracket arm is a cam shaft 46. A bracket 47 pivotally mounted on the cam shaft has upper ring 48, and a circular hole 49 to receive a spherical bearing 50 connected to the free end of the connecting rod 36 to the needle bar gate. The foregoing arrangement forms a universal joint between the bracket 47 and the connecting rod. A similar arrangement is dis closed in the United States patent of R. E. Johnson, No. 2,862,468; granted Dec. 2, 1958. Rotation is imparted to the cam shaft by a worm 51 on the arm shaft and a meshing worm wheel 52 on the cam shaft. A cam 53 having a. peripheral cam surface 54 is exchangeably mounted on a flange 55 on the cam shaft and yieldably held on the flange by a spring clip 56. The cam is fixed to rotate with the cam shaft by a pin 57 on the flange extending into a hole 58 in the cam.

Pivotally mounted on a boss 59 in the bracket arm by a pivot screw 60 is a needle position lever 61. The needle position lever has a fulcrum projection 62 which bears against the wobble plate 37. A handle 63 is connected to the free end of the needle position lever by two screws 64 and 65. The handle extends through the uppermost slotted apertures 22, 20, 24 in the front of the bracket arm, the plate, and the control panel, respectively. A knob 66 is formed on the free end of the handle.

Mounted in another boss 67 in the bracket arm by a set-screw 68 is a post 69. The post has an upper pilot portion 70 forming a shoulder 71 as shown in FIG. 4, a U-shaped cam follower means 72 having lower and upper arms 73 and 74, respectively, is pivotally mounted on the pilot portion of the post with the pilot portion extending through aligned bores 75 and 76 formed in the lower and upper arms, and the lower arm resting on the shoulder 71 of the post. An upwardly extending cam follower 77 is formed on the upper arm 74 of the cam follower means to contact the peripheral cam surface 53 of the exchangeable cam.

A11 upwardly extending handle 78 is also formed on the upper arm of the cam follower means. Pivotally mounted on the pilot portion 70 of the post above the lower arm of the cam follower means is a throw-out lever 79, having a clearance bore 80 for the pilot portion of the post. The throw-out lever has a cam surface 81, and is biased by a torsion spring 82, mounted on the pilot portion of the post above the lever. The torsion spring has two limbs 83 and 84 of which one arm 83 bears against the lower arm of the cam follower means 72 and the other arm 84 bears against the lever to bias the lever in a counterclockwise direction. Mounted on the upper arm of the cam follower means is a contacting member 85 for contacting the wobble gate 37. The contacting member has a clearance bore 86 for the pilot portion of the post and-is connected to the upper arm 74 of the cam follower means 72 by two screws 87 and 88. One of the two screws extends through a clearance hole 89 in the contacting member into a tapped hole 90 in the upper arm of the cam follower means. The other screw 88 is a shoulder screw on which an eccentric sleeve 91 with a hexagonal upper portion 92 is pivotally mounted. The eccentric sleeve 91 extends into a slot 93 in the contacting member and the screw 85 threads into a tapped hole 94 in the upper arm of the cam follower means. The eccentric 91 member provides a slight lateral adjustment feature for the contacting member so that the zigzag motion of the needle bar may be laterally adjusted. The cam follower means is held on the pilot portion of the post by a collar 95 with a setscrew 96.

Connected to the ring 48 of the bracket 47 which is connected to the end of the connecting rod 36 to the needle bar gate by the spherical bearing 40 on the connecting rod, is a stitch width control lever 97. The stitch width control lever is connected to the ring of the bracket by two screws 98 and 99. A handle 100 is connected to the free end of the stitch width control lever by a screw 101 and a stud 102 which prevents pivotal movement of the handle about the last mentioned screw 101. The handle extends through the lowermost slotted apertures 23, 21, 25, in the front of the bracket arm, the plate, and the control panel, respectively. A knob 103 is formed on the free end of the handle. Mounted on the two screws 98 and 99 which connect the stitch Width control lever to the ring of the bracket is a camming member 104 for hearing against the cam surface 81 on the lever 79 on the post. The camming member has two clearance slots 105 and 106 for the screws 98 and 99 and an upwardly projecting handle to provide a lateral adjustment feature.

In operation, when it is desired to sew straight stitches, the handle 100 of the stitch width control lever 97 is moved into the notch 26 in the upper edge of the lowermost slotted aperture in the control panel beneath the indicia 1. The foregoing movement causes the camming member 104 on the stitch width control lever to bear against the cam surface 81 on the throw-out lever 79 which is properly positioned by the torsion spring 82. The foregoing movement causes the throwout lever 79 to pivot in a counterclockwise direction on the pilot portion 70 of the post 69 to force the wobble plate 37 out of contact with the contacting member 85 on the cam fol lower means 72 in opposition to the tension coil spring 36. Thus, the sewing machine is free to sew perfectly straight stitches uninfluenced by any slight movement of the wobble plat 37 which might be caused by wide tolerances, parts out of adjustment, or worn parts. The foregoing is accomplished without adding any additional operation on the part of an operator, and irregardless of whether the needle position control lever is in left, center, or right position.

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. In a zigzag sewing machine having a frame, a needle bar gate mounted in the frame, a needle bar mounted on the needle bar gate, a cam shaft mounted in the frame, means for imparting rotation to the cam shaft, a cam having a cam surface mounted on the cam shaft for rotation with the cam shaft to impart lateral oscillation to the needle bar gate, cam follower means mounted in the frame, a cam follower on the cam follower means for contact with the cam surface of the cam, a contacting means on the cam follower means for movement with the cam follower, a connecting means having one end connected to the needle bar gate for transmitting lateral oscillation to the needle bar gate, abutment means at the other end of the connecting means for engaging the contacting means on the cam follower means, means for biasing the abutment means on said connecting means against the contacting means on said cam follower means, and operator influenced means for changing the stitch width from zero to a predetermined maximum, an improved straight stitch control mechanism including a throw-out lever operated by the means for changing the stitch width to move the abutment means on the connecting means out of engagement with said contacting means on said cam follower means when said means for changing the stitch width is shifted into a position dictating a zero stitch width.

2. The improved straight stitch control mechanism of claim 1 in which the throw-out lever has a cam surface and the means for changing the stitch width includes a camming means which bears against the cam surface of the lever when the means for changing the stitch Width is set for zero stitch width to cause the throw-out lever to move the abutment means on the connecting means out of engagement with the contacting means on said cam follower.

3. The improved straight stitch control mechanism of claim 2 in which the means for changing the stitch width includes a stitch width control lever and said camming means is on the stitch width control lever.

4. The improved stitch width control mechanism of claim 3 which includes means for adjusting the position of the said camming means on said stitch width control I lever.

5. The improved straight stitch control mechanism of claim 1, in which the cam follower comprises a lever, and in which a single pivotal mounting means in the sewing machine pivotally supports both the cam follower lever andthe throw-out lever.

6. The improved straight stitch control mechanism of claim 5 which includes a torsion spring having two limbs mounted on the means for pivotally mounting the lever and the cam 'follower lever, with one of the torsion spring limbs bearing against the cam follower means and the other torsion spring limb bearing against the throwout lever to bias the cam surface of the throw-out lever into a position for receiving the camming means when the means for changing the stitch width is set for zero stitch width.

References Cited UNITED STATES PATENTS 3,081,724 3/1963 .1 Bono 1l2158 RICHARD J. SCANLON, JR., Primary Examiner

Images