US3026835A

US3026835A - Pneumatic needle-bar positioner for sewing machines

Info

Publication number: US3026835A
Application number: US725021A
Authority: US
Inventors: Richard H Hall
Original assignee: Individual
Current assignee: Individual
Priority date: 1958-03-31
Filing date: 1958-03-31
Publication date: 1962-03-27
Anticipated expiration: 1979-03-27

Description

R. H. HALL March 27, 1962 PNEUMATIC NEEDLE-BAR POSITIONEIR FOR SEWING MACHINES Filed March 31, 1958 5 Sheets-Sheet l INVENT OR. Richard H.Ha1l,

AT TOENEY.

March 27, 1962 R. H. HALL 3,026,835

PNEUMATIC NEEDLEBAR POSITIONER FOR SEWING MACHINES Filed March 31, 1958 Sheets-Sheet 2 I 55 15b 51a 1 21a 27 125 21 P510 293 45 9 '59 27a 27a 15 Fig. 4 /3 29' 58 57c I "A 37b 452 4? 57' 57a *9 a INVENTOR:

RicharAH. Hall,

BY wax flaw ATTORNEY March 27, 1962 R H 3,026,835

PNEUMATIC NEEDLE-BAR POSITIONER FOR SEWING MACHINES Filed March 31, 1958 5 Sheets-Sheet 3 66 INVENTOR.

Rlchard Hfiall,

BY WW @LJM AT TORNFYT United States atent 3,026,835 PNEUMATIC NEEDLE-BAR POSHTIONER FOR SEWING MACHINES Richard H. Hall, 3907 Estes Road, Nashville, Tenn. Filed Mar. 31, 1958, Ser. No. 725,021 8 Claims. (Cl. 112-221) This invention relates to a pneumatic needle-bar positioner for sewing machines.

More particularly the invention pertains to pneumatically operated means for positively positioning the needle bar of a sewing machine in a predetermined position (usually up but selectively down if preferred) at the end of each sewing operation involving raising of the presser foot, said means being constructed and arranged to forwardly rotate the shaft reciprocating the needle bar thru an angle approaching 350 deg. (or backwardly about deg.) to prevent undesirable slack in the threads (as occurs in needle positioners which produce half of the time backward rotations up to 180 deg).

3,026,835 Patented Mar. 27, 1932 'drivingly connected to shaft by an automatically op- This disclosure is an improvement over applicants previously filed application S.N. 610,362, filed September 17, 1956, for Means Responsive to Sewing-Machine Presser-Foot Operation for Work-Control Positioning of Needle Bar, the disclosure of which is hereby included herein by reference. 'Its purposes are fundamentally the same as those of said prior application, namely automatic positive positioning of the needle in predetermined position relative to the work when the presser foot is raised and for the reasons stated therein, but it advantageously differs therefrom in providing pneumatic operating means in place of knee-powered means and in very desirably providing up to 350 deg. forward rotation of the needle-bar-driving shaft, thus leaving only an occasional (1 in 36) backward rotation of 10 deg. or less, which does not produce an objectionable thread slackening, as compared with the 180 deg. backward rotation of priorart needle-bar posi tioners.

It is accordingly the principal object of this invention to provide a needle-bar positioner in which threadslackening (backward) movement thereof is reduced to a minimum both in frequency and in amount of movement.

It is a further object to provide such a device with pneumatic operating means.

It is a further object to provide such a device with automatic clutch means for disconnecting the belt-driven pulley from the hand-wheel shaft.

These and other objects and advantages of the invention will become apparent as the following detailed description proceeds.

In the drawings:

FIG. 1 is a perspective view of a preferred embodiment of the invention.

FIG. 2is a front elevational view of the unenergized device of FIG. 1 in partial axial section.

FIG. 3 is a view similar to FIG. 2 showing the pants pneumatically moved to needle-positioning positions.

FIG. 4 is a view, similar to FIG. 2 of a modified construction.

FIG. 5 is a perspective view of the automatic air valve.

FIG. 6 is an enlarged elevational view of the valve in vertical section taken on the plane of the axes of the tapped air inlet and outlet passages.

FIG. 7 is a view similar to FIG. 6 but showing the valve parts in device-operating positions.

With reference now to FIGS. 1 and 5, the numeral 11 designates the base of a conventional factory-type sewing machine which rests upon machine board 12 and from which rises the overlying hollow head member 13.

erated clutch mechanism which permits the pulley 19 to free-wheel when the needle positioner is in operation.

The automatic clutch mechanism comprises the hand wheel 21 which is keyed to the shaft 15 for limited axial movement thereon. A compression spring 23 acting between flange abutment 15a and washer 21a normally forces wheel 21 to the left (FIGS. 2 and 3) so as to grip the pulley 19 between the two

clutch disks

25 and 26.

Disk 26 is held against axial movement away from pulley 1? by the flange 27 fixed to the extension 15b of the hand-wheel shaft 15 by its integral hub 27a upon which the pulley 19 free-wheels when declutched.

The pneumatic operator comprises the shaft extension 15b rigidly coupled to shaft 15 and in accurate alinement therewith, and the pneumatic cylinder 29 concentrically mounted there around. Cylinder 29 is provided with an enlarged extension sleeve 29a slidably mounted in the support block 31 and keyed thereto at 31a. Block 31 is formed of two parts connected by screws 31b. Block 31 is accurately and adjustably positioned and held against rotation by the rigid structure consisting of

screws

32 and 33 adjustably connected to block 34 by nuts 34', the articulated arm 35, and the anchor post 36 fixed to the base portion 11.

The flexible hose 3'7 conducts compressed air to cyl-' inder 29. Air enters thru passage 39a in the cylinder head 39. A pair of 0 rings 40 and 41 of resilient material seal the joints between the head and the cylinder 29 and between the rotating shaft 15b and its embracing bore thru head 39. A U-gasket 43 of resilient material forms the sealing portion of the annular piston completed by the flange 45a on the sleeve-cam 45. A spring 47, compressed between flange 45a and guide ring 49 for the sleeve-cam 45, normally holds the parts in their FIG. 2 positions. When compressed air enters port 39a it moves sleevecam 45 to the left so that its 350 deg. heiical edge 45b engages a roller-bearing cam follower 51 to rotate the shaft 15-15b thru an angle up to about 350 deg. in the forward direction. A pin 53 (fixed to guide ring 49) is engageable against the straight-edged face 45c of the cam 45 and prevents the free-floating sleeve cam 45 from being rotated by cam-followerexerted counter force. Follower 51 is mounted on post 51a screwed into a radial bore in shaft 15b. The outer end of shaft 15b is journaled in the bearing sleeve 55 mounted on the head 57 fixed to the end of cylinder extension 29a. If the par-ts are in the positions of FIG. 2 whenthe air pressure is applied, the sleeve 45 will not move follower 51 since its wedge-shaped end will not be forced between it and pin '53. Rather, the sleeve 45 will be moved away from pin 53 by follower 51 until pin 53 is engaged by surface 45b near the socket 45d. Then the sleeve 45 will be rotated backwardly and will move the shaft, thru follower 51, about 10 deg. backwardly (which will not move the needle bar appreciably, since it is in this case adjacent the bottom of its stroke).

Since cylinder 2.9-29a is mounted in block 31 for slight axial movement, air pressure causes the same to move to the right (FIGS. 2 and 3) thus producing clutchoperating engagement of pins 59 by the head 39. Pins 59 are slidably received in bores thru the hub 27a.

The automatic control mechanism is illustrated in FIGS. 5-7. Said mechanism comprises a clamp 61 consisting of a pair of plates 61a and 61b having mating semicylindrical channels in their opposed faces which close upon and grip the conventional presser-foot operating rod 63 when they are drawn together by screws (not visible) the heads of which lie against the far side of plate 61a. The lower half of plate 61b carries the valve block 65 fastened thereto by the screw 66. Compressed air is fed to block 65 by the hose 67 and conventional coupling elements 68-70. A valve plunger 71 has a protruding operator 71a engageable against the top of base 11. when the presser-foot operating rod 63 is depressed toraise the presser foot. This operation raises valve disk 71b away from the sealing O-ring 72 to permit compressed air to flow into chamber 65a and thence thru couplers 7375 into the cylinder 29. When the rod 63 is raised to lower the presser-foot into sewing position, valve stem 71 drops to its FIG. 6 position shutting off the supply of compressed air and discharging that in the cylinder 29 thru ports 65b so that the needle-bar-positioning cam 45 can be returned to its inoperative position of FIG. 2 by spring 47.

In the modification of FIG. 4, simplified by the omission of the clutch mechanism of the previously described species, the arrangement and actions of the parts are reversed. The shorter shaft extension 15b supports the near end of cylinder 29' thru its head 58 attached thereto by screws 58. A flange 15c engages a thrust bearing 59' backed up by the collar portion of head 58 to prevent undue thrust against shaft 15b when the cam 45' is pneumatically thrust against the follower 51. The outer end of shaft 15b is journaled in a bore 57a in the end of member 57, the left end of which is enlarged to form the other cylinder head and is attached to cylinder 29' by screws 60'.

The cam 45' freely slides over the outer surface of member 57 and is held against unlimited rotation thereon by' the screw pin 53 which also helps locate and support the outercam-guiding ring 49 and the centrally located end of member 57'. A spring 47 compressed between the flange 45a and guide ring 49' normally holds the parts intheir FIG; 4 positions. The cylinder 29' is supported by means equivalent to the parts 3136 previously described but not slidable therein since the clutch-operating movement of the cylinder is not needed in this species. Bore 570' is an oiling port.

Compressed air enters cylinder 29 thru a port 57b connected by couplers 37a and 37b to hose 37, which in turn is connected to an automatic valve, such as 6175 previously described. The entering air forces the U- gasket 43 against cam flange 45a to rotate the'shaft 15b by engaging the follower 51 and pin '53 as in the firstdescribed species.

While I have described a preferred embodiment of my invention it is to be understood that many changes can be made in the size, shape, composition and arrangements of the partsiwithout departing from the spirit of the invention asdefined by the subjoined claims. For examples, the cam-thrusting means could be solenoid or human-powered (.by knee, hand, foot, etc.); or a manually or foot-operated switch or valve could be substituted for the automatic valve disclosed.

Having thus described my invention, I claim:

. 1. Means for positioning the needle bar and thereby the needle of a sewing machine in a preselected stroke position, comprising: a cam member and a cam-follower member having normally disengaged surfaces providing when said surfaces are engaged relative rotation in one direction therebetween closely approaching 360", means operatively connecting one of said members for rotation with the needle-bar drive shaft of a sewing machine, and power-applying means for operating the other of said members into engagement with said one member to position said needle bar in said preselected position by turning said needle-bar drive shaft in most instances in a forward direction to minimize frequency of occurrence and amount of undesirable backward movement of said shaft.

2. Structure according to claim 1, said power-applying means being coupled to presser-foot-operating mechanism of said sewing machine for automatic control thereof in response to operation of said presser foot.

3. Structure according to claim 2, said power-applying means being a pneumatic cylinder and said coupling means being a valve mounted on the conventional operating rod for said presser foot and operated in response to movement of said rod.

4. Structure according to claim 1, said power-applying means being a pneumatic cylinder alined with an axial extension of said needle-bar drive shaft, said cam member being a sleeve operated by the piston of said cylinder, and said cam-follower member being a post mounted on said axial extension.

5. Structure according to claim 4, said sleeve having a highly pitched helical edge engageable with said cam follower and having a circumferential extent approaching 360.

6. Structure according to claim 5, said cam member being free-floating in said cylinder and said cylinder having a fixed second cam follower engageableagainst a straight edge on said sleeve to limit its rotation within said cylinder.

7. Structure according to claim 1 and additionally comprising clutch means automatically operated by operation of said power-applying for discontinuing the drive between the power supply for said sewing machine and said needlebar drive shaft upon operation of said positioning means.

8. Structure according to claim 7, said clutch means comprising at least one friction member compressed between the driving pulley for said needle-bar drive shaft and means operable by movement of said power-applying means, the latter being a pneumatic cylinder alined with said shaft and mounted for slight reactive longitudinal movement during energization.

References Cited in the file of this patent UNITED STATES PATENTS 1,181,363 Anschutz et al. May 2, 1916 1,470,687 Clarke Oct. 16, 1923 FOREIGN PATENTS 375,597 France May 17', 1907