US3420198A

US3420198A - Needle bar and presser bar subassembly

Info

Publication number: US3420198A
Application number: US631271A
Authority: US
Inventors: Robert G Greulich
Original assignee: Singer Co
Current assignee: Singer Co
Priority date: 1967-04-17
Filing date: 1967-04-17
Publication date: 1969-01-07
Anticipated expiration: 1986-01-07

Description

Jan. 7, 1969 R. G. GREULICH NEEDLE BAR AND PRESSER BAR SUBASSEMBLY Sheet Filed April 17, 1967 INVENTOR. Robert G. Greuh'ch BY W 9 ATTORNEY Jan. 7, 1969 R. e. GREULICH NEEDLE BAR AND PRESSER BAR SUBASSEMBLY Sheet Filed April 17, 1967 'NVENTOR. Robert G. Greulich BY WTQRNEY' Witness dosa 1 M4 T94;

Jan. 7, 1969 R. G. GREULICH 3,420

NEEDLE BAR AND PRESSER BAR SUBASSEMBLY Filed April 17. 1967 Sheet 3 of 5 INVENTOR. Robert G. Greulich Witness BY 406! IN! 7241 2%0RNEY Jan. 7, 1969 R. G. GREULICH NEEDLE BAR AND PRESSER BAR SUBASSEMBLY Sheet Filed April 17. 1967 Jan. 7, 1969 R. e. GREULICH 3,

' NEEDLE BAR AND PRESSER BAR SUBASSEMBLY Filed April 17. 1967 Sheet 5 0f 5 BY 4 in TM; 7 y

TORNE Y United States Patent 01 ice 4 Claims ABSTRACT OF THE DISCLOSURE A needle bar and presser bar subassembly for sewing machines preassembled before final assembly in the frame of a sewing machine. The needle bar and presser bar subassembly includes means for lifting a presser bar when desired.

Cross-reference to related application The feed mechanism and long shuttle mechanism are more fully disclosed in a copending United States patent application Ser. No. 631,339, filed Apr. 17, 1967.

Background of the invention (1) Field of the invention-The invention relates to needle driving mechanisms, presser devices, and presser lifting devices for sewing machines.

(2) Description of the prior are.--Heretofore, needle bars, presser bars, and presser lifting devices have been assembled separately in sewing machine frames. The foregoing procedure is expensive because the entire machine frame must be set up in a drill jig and holes bored for the needle bar and the presser bar. If a large number of machines are to be made, a special drilling machine must be built. In addition, assembly of the parts directly into the machine frame is a tedious time-consuming task whether during initial assembly or later to replace worn or broken parts.

Summary of the invention It is therefore an object of the invention to provide a needle bar and presser bar subassembly for sewing machines.

Another object of the invention is to provide a needle bar and presser bar subassembly which includes means for lifting a presser bar.

Another object of the invention is to provide a needle bar and presser bar subassembly which includes a manual presser lifter which can be composed of a single length of wire.

Another object of the invention is to provide a needle bar and presser bar subassembly which can be composed of a minimum number of inexpensive parts.

Other objects and a fuller understanding of the invention may 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 front perspective view of a sewing machine incorporating the invention;

3,420,193 Patented Jan. 7, 1969 FIG. 2 is a cross-sectional view through the sewing head of the sewing machine of FIG. 1 as viewed from the standard of the sewing machine;

FIG. 3 is a partially sectioned detail view of the needle bar and presser bar subassembly of FIG. 2 with the presser foot in raised position;

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

FIG. 5 is an enlarged perspective view bar and presser bar subassembly of FIG. 2;

FIG. 6 is an exploded perspective view of the inside of the front shell of the frame of the sewing machine;

FIG. 7 is an elevational view of the inside of the front shell of the frame of the sewing machine; and

FIG. 8 is an elevational view of the inside of the rear shell of the frame of the sewing machine.

of the needle Description of the preferred embodiment With reference to the drawings, the invention is illustrated embodied in a sewing machine for children.

The sewing machine has a frame including a front shell 11 and a rear shell 12 each composed of plastic. Each shell has a bed portion 13 or 13a, a standard portion 14 or 1411 rising from one end of the bed portion, an arm portion 15 or 15a at the top of the standard portion overhanging the bed portion, and a sewing head portion 16 or 16a at the free end of the arm portion. An L-sha-ped control panel 17 is formed on the arm and standard portions of the front shell.

The two shells register with each other through a pe- Tipheral flange 18 and bosses 19 formed in the front shell which mate with a peripheral groove 20 and holes 21 formed in the rear shell. The shells are held together by three

screws

22, 23 and 24. Two of the screws extend through

clearance holes

25 and 26 in the bed portion of the rear shell into tapped

holes

27 and 28 in bosses 29 and 30 formed in the bed portion of the front shell. The remaining screw 24 extends through a clearance hole 31 in the arm portion of the rear shell into a tapped hole 32 in a boss 33 formed in the arm portion of the front shell. Also holding the two shells together is an arbor 34 for a thread tension device indicated generally at 35. The arbor extends through a clearance hole 36 in the front shell into a tapped hole 37 in a boss 38 formed in the rear shell.

Mounted in the arm and standard portions of the front shell is an L-shaped bell crank 39 having upper and

lower arms

40 and 41. The bell crank has a hole 42 in the upper arm by which it is pivotally mounted on the boss 38 for one of the screws which hold the two shells together.

The bell crank also has a group of three small holes 43 on the free end portion of the lower arm, a group of three small holes 44 in the juncture of the lower and upper arms, a single small hole 45 in the free end portion of the upper arm, and an upwardly projecting hook 46 formed at the free end of the upper arm.

A link 47 is pivotally mounted in one of the three small holes 43 in the lower arm to transmit motion to a long shuttle mechanism indicated generally at 48 and a feed mechanism indicated generally at 4Q. Groups of three small holes are used to provide an adjustment feature. The long shuttle mechanism and the feed mechanism are more fully described in the previously cited copending United States patent application.

' A second link 50 is pivotally mounted in one of the three small holes 44 in the juncture of the lower and upper arms. The other end of the second link is pivotally mounted in one of three small holes 51 in a crank 52. Rotating motion is imparted to the crank by an electric motor 53 through a gear train indicated generally at 54 or, in the alternative, by a coaxial handwheel 55 which can be manually rotated by a removable hand crank 56. Rotation of the crank 52 transmits oscillating motion to the bell crank 39 through the second link 50.

The hook 46 at the free end of the upper arm of the bell crank and the small hole 45 in the free end portion of the upper arm transmit motion to a thread take-up lever 57 and a needle bar 58, respectively, both of which are presently to be described.

The thread take-up lever 57 is pivotally mounted on a boss 59 on a mounting block 60. The take-up lever has a keyhole 61 and the mounting block has a key 62 which prevents the take-up lever from being removed from the mounting block except when the keyhole is correctly aligned with the key. The mounting block has opposed

tabs

63 and 64 which seat in

recesses

65 and 66 in

bosses

67 and 68 formed in the sewing head portions of the two shells to removably mount the mounting block in the frame of the sewing machine. The free end of the take-up lever 57 extends through a vertical slot 69 in the sewing head portion of the front shell, and an eyelet 70 for thread is formed in the free end of the take-up lever. The hook 46 at the free end of the upper arm of the bell crank lies underneath the lower portion of the free end of the take-up lever.

The needle bar 58 is part of a needle bar and presser bar subassembly indicated generally at 71. The needle bar and presser bar subassembly includes a second frame 72 having two

parallel holes

73 and 74. The needle bar is mounted in one of the holes 73, and a presser bar 75 is mounted in the other hole 74.

The hole 74 for the presser bar has a reduced portion 76 and an enlarged portion 77 thereby forming a shoulder 78 at an intermediate portion of the hole. Diametrically opposed keyways 79 are formed in the reduced portion 76 of the hole.

Integrally formed at the lower end of the presser bar is a presser foot 80 which forms a shoulder 81 on the presser bar, and diametrically opposed keys 82 are formed on the presser bar. The presser bar is mounted in the hole 74 for the presser bar with the keys 82 sliding on the keyways 79 to prevent rotation. A coil spring 83 is mounted on the presser bar between the shoulder 81 formed by the presser foot and the shoulder 78 between the enlarged and reduced portions of the hole for the presser bar.

In order to lift the presser bar and with it the presser foot, a manual presser lifter 84 is provided. The presser lifter includes a lever 85 formed from a single length of wire with an intermediate portion bent into a substantially triangular cam 86 having

sides

87, 88 and 89, and an end portion 90 bent into a position substantially perpendicular to the plane of the cam. The free end portion of the lever serves as a handle. The bent end portion 90 of the lever extends through a vertical slot 91 in the frame of the needle bar and presser bar subassembly into a radial hole 92 in the presser bar. The cam portion 86 of the lever bears against a bearing surface 93 in the bottom of a groove 94 formed on the frame by a raised ledge 95 on a peripheral flange 96 around the frame of the needle bar and presser bar subassembly.

Mounted in an axial hole 97 in the lower end of the needle bar 58 is a needle 98 having a shank 99 and an eye 100. A needle positioning screw 101 obstructs the hole 97 for the needle so that the needle can only be inserted into the hole for the needle with a flat surface on the shank facing the inner end of the needle positioning screw. Thus, it is impossible to incorrectly connect the needle 4 to the needle bar. The needle is held in the hole in the needle bar by a clamping screw 102, and a crank pin 103 projects laterally from the top portion of the needle bar.

The frame 72 of the needle bar and presser bar subassembly has a lower shoulder 104 formed by the peripheral flange 96 and an intermittent upper shoulder 105 formed by the tops of lateral bosses 106. The

shoulders

104 and 105 seat in

recesses

107 and 108 formed between

shelves

109 and 110 and floors 111 and 112 of the sewing head portion of the shells of the frame to mount the needle bar and presser bar subassembly in the frame. The crank pin 103 on the needle bar seats in the single small hole 45 in the free end portion of the upper arm of the bell crank 39, the presser foot opposes the feed mechanism 49, and the lever of the presser lifter 84- projects through a vertical slot 113 in the sewing head portion of the rear shell of the frame.

In operation, reciprocating motion is imparted to the needle bar 58 by oscillating motion of the bell crank 39 which is connected to the needle bar by the crank pin 103 seating in the small hole 45 in the free end portion of the upper arm of the bell crank.

With specific reference to FIGS. 2 and 3, when it is desired to raise the presser foot 80, the lever 85 is manually moved upwardly so that the bottom side 89 of the triangular cam 86 bears against the bearing surface 93 on the frame 72 of the needle bar and presser bar subassembly. When the lever is moved downwardly to lower the presser foot, one of the lateral sides 88 of the triangular cam bears against the bearing surface on the frame of the needle bar and presser bar subassembly.

Although the invention has been described in its preferred form with a certain degree of particularly, 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 may be resorted to Without departing from the spirit and the scope of the invention.

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

1. A needle bar and presser bar subassembly adapted for mounting as a unit in a sewing machine having a frame, a presser bar for a presser foot, a needle bar for a needle, means mounted in the frame of the sewing machine for imparting reciprocation to the needle bar, means for connecting the needle bar to the means for imparting reciprocation to the needle bar, and a complementary stitch-forming mechanism mounted in the frame, said needle bar and presser bar subassembly comprising a second frame separate from said sewing machine frame having two holes, the needle bar mounted in one hole and the presser bar mounted in the other hole, means for biasing the presser bar downwardly, means connected to the frame of the needle bar and presser bar subassembly for lifting the presser bar when desired, and means for mounting the needle bar and presser bar subassembly comprising said second frame as a separate unit in the frame of the sewing machine so that the needle bar can be connected to the means for imparting reciprocation to the needle bar, a needle on the needle bar can cooperate with the complementary stitch-forming mechanism to form stitches, and a presser foot on the presser bar can act upon work fabric in which stitches are to be formed.

2. The needle bar and presser bar subassembly of claim 1 in which the frame of the sewing machine includes two shells which together from the frame, and the needle bar and presser bar subassembly comprising said second frame is mounted as a unit in one shell and entrapped in the frame by the other shell.

3. The needle bar and presser bar subassembly of claim 1 in which the frame of the needle bar and pressure bar subassembly has a bearing surface and a slot parallel to and communicating with the hole in the frame for the presser bar, and the means for lifting the presser 'bar includes a lever, a cam on the lever, and means for connecting the lever to the presser bar through the slot in the frame so that the cam on the lever can bear against the bearing surface on the frame for lifting the presser bar when the lever is manually manipulated.

4. The needle bar and presser bar subassembly of claim 3 in which the bearing surface on the frame of the needle bar and presser bar subassembly is at the bottom of a groove fromed on the frame, the presser bar has a small radial hole in the side which can be aligned with the slot in the frame which communicates with the hole for the presser bar, and the lever is formed from a single length of wire having an end portion pivoted in the small radial hole in the needle 'bar, an intermediate portion bent into a figure forming the cam which bears against the bearing surface on the frame, and a free end portion serving as a handle.

References Cited UNITED STATES PATENTS 2,346,637 4/1944 Wesson 112235 2,481,286 9/1949 Bouwkamp et a1. 112-235 2,848,966 8/1958 Ritter et a1. 112238 2,892,429 6/1959 Fischbein 112--235 PATRICK D. LAWSON, Primary Examiner.