US3320914A - Air operated needle positioners - Google Patents

Description

y 2 1967 K. D. ADAMS 3,320,914

AIR OPERATED NEEDLE POSITIONERS Filed Oct. 7, 1964 2 Sheets-Sheet 1 Fig.l

I NVEN TOR.

Kenneth D. Adams WITNESS Fig.4

TTORNE Y AIR OPERATED NEEDLE POSITIONERS Filed Oct. 7, 1964 2 Sheets-Sheet 2 I N VENTOR. Kenneth D. Adams 99 BY WITNESS 85/ z/pmawgb F :93 @Ma Q,

A T TORNE Y United States Patent 3,32%,914 AIR OPERATED NEEDLE PQSITIQNERS Kenneth D. Adams, Long Valley, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jersey Filed Oct. 7, 1964, Ser. No. 402,234 3 Claims. (Cl. 112-219) This invention relates to a needle positioning device for a sewing machine.

It is an object of this invention to provide a novel and effective sewing machine needle positioning device which may be applied readily to a conventional sewing unit in which the sewing machine is carried on a table top with the sewing machine drive motor or power transmitter carrier beneath the table top.

The novel needle positioning device of this invention may be carried out of sight beneath the sewing machine supporting table top and inserted between the drive motor or power transmitter and the sewing machine so that it does not detract from the appearance of the sewing unit, does not interfere in any way with the handling of work fabrics being stitched and does not impede access to or manipulation of the conventional sewing machine controls.

It is an object of this invention to provide a needle positioning device completely contained within a unit spaced from the sewing machine and from the drive motor or power transmitter so as to obviate necessity for the presence or attachment of any needle positioning mechanism on the sewing machine or power transmitter and so as to obviate the necessity of any modification of a conventional sewing machine and power transmitter other than the provision of an appropriate pulley on the sewing machine main shaft.

With the above and additional objects and advantages in view as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 is an end elevational view of a sewing unit having the needle positioning device of this invention applied thereto,

FIG. 2 is an enlarged vertical cross sectional view taken lengthwise along the countershaft of the needle positioning device substantially along line 22 of FIG. 1,

FIG. 3 is a cross sectional view taken transversely of the countershaft of the needle positioning device substantially along line 33 of FIG. 2,

FIG. 4 is an end elevational View of the centrifugal switch with a portion broken away and illustrated in cross section taken substantially along line 4-4 of FIG. 2 and FIG. 5 is a wiring diagram illustrating the manner of connection of the electrical components of this invention.

Referring to the drawings, FIG. 1 illustrates the conventional arrangement of a sewing machine frame 11 on a table top 12 which is floor supported by legs 13. The sewing machine includes an endwise reciprocating needle 14 which receives its endwise motion from a rotary shaft 15 journaled in the sewing machine frame in a manner which is conventional in the art. An electric mot-0r or power transmitter 16 which is supported beneath the table top and preferably on the table legs 13 supplies the primary drive for the rotary shaft 15 of the sewing machine. In a conventional sewing machine drive arrangement without the needle positioning device of this invention, the power transmitter would be connected as by a drive belt directly to the rotary shaft 15 of the sewing machine. The power transmitter 16 is preferably of the conventional type including a pulley 17 associated with a clutch brake unit (not shown) which is controlled by an operating lever 18, the position of which may be operator in- 3,320,914 Patented May 23, 1967 fiuenced by way of a foot treadle 19 carried by a cross brace 20 between the table legs and connected by means of a rod 21 to the power transmitter operating lever 18. In the operation of the conventional power transmitter, depression of the upper portion of the foot treadle 19 by the operator will etfect engagement of the power transmitter clutch to drive the power transmitter pulley 17, while depression of the lower portion. of the foot treadle which is termed heeling in the art will influence engagement of the brake which stops rotation of the pulley 17. An electrical switch 22 is carried preferably on the cross brace 20 between the table legs and arranged so as to be operated when the treadle is heeled as a means for signaling initiation of operation of the needle positioner of this invention as will be described hereinbelow.

In applying the needle positioner of this invention to the sewing unit above described, the conventional direct belt connection between the power transmitter pulley 17 and the sewing machine shaft 15 is eliminated. Beneath the table top 12 is secured a needle positioner frame 30, as for instance, by brackets 31, 32. Journaled in the needle positioner frame 30 in bearings 33 is a countershaft 34 as best illustrated in FIG. 2. Journaled on bearings 35 on the countershaft is an arbor 36 to which is secured by a key 37 a pulley unit including a V-belt pulley 38 and a clip belt pulley 39. The V-belt pulley 38 is con nected by a V-belt 40 to the power transmitter pulley 17. The clip belt pulley 39 is connected by means of a clip or lug belt 41 to a clip belt pulley 42 secured on the sewing machine shaft 15. Preferably the clip belt pulleys 39 and 42 are of equal size so that the sewing machine shaft 15 and the pulley unit 38, 39 will turn in unison and occupy similar angular relation.

The arbor 36, which will also rotate with the pulley unit 38, 39 in timed relation with the sewing machine shaft 15 serves as a secondary driven member as will be described hereinbelow and for this purpose is formed with a projection 43 forming a radial abutment surface 44.

Also secured for rotation with the arbor 36 and the pulley unit 38, 39 by the key 37 is a centrifugal switch indicated generally at 50. As illustrated in FIGS. 2 and 4, the centrifugal switch 50 comprises a body portion 51 preferably of non-conducting material such as Bakelite, hard rubber or the like which is formed with a plurality of radial bores 52 extending from the outer periphery into an annular recess 53 formed in one side of the body portion 51. The annular recess 53 accommodates a pair of metallic slip rings 54 and 55 which slip rings are separated from each other by an air space and extend each to a different degree into the annular recess 53. A metallic ball 56 is positioned in each of the radial bores 52 and constrained therein by a peripheral band 57 secured about the body portion 51 of the switch. For convenience of assembly the body portion 51 of the: centrifugal switch may be formed with a series of bores 58 transversely of the radial bores 52 so as to accommodate a retaining wire 59 which will prevent escape of the metallic balls prior to application of the peripheral band 57. As illustrated in FIGS. 2 and 4, when the centrifugal switch is at rest or substantially at rest, at least one of the metallic balls will drop into engagement across the slip rings 54 and 55 in any position of the centrifugal switch. When the pulley unit 38, 39 is rotating, however, centrifugal forces acting on the metallic balls will move each of them radially outwardly out of engagement with the slip rings. A pair of brushes 60, 61 which are carried by the needle positioner frame 312 are biased each into engagement with one of the slip rings 54 and 55, as illustrated in FIG. 2, and each provide a terminal post whereby the centrifugal switch 50 may be connected electrically into the control circuit for the needle positioner which will be described hereinbelow.

Secured fast on the countershaft 34, as by a setscrew 70 is the hub portion 71 of a secondary drive member, indicated generally as 72, which is adapted to position the sewing machine needle. The hub portion 71 is formed with a flange 73 in which is provided a radial slot 74 accommodating a plunger 75 which is slidablc radially of the flange in the slot 74. An arched spring 76, which is anchored through an aperture 77 in the flange 73 opposite the plunger 75, encompasses the hub portion 71 and passes through a clearance aperture '78 in the flange 73 into engagement with the plunger 75 and serves to bias the plunger radially inwardly into a position engageable with the abutment surface 44 formed on the arbor 36.

Pivoted as at 80 on the needle positioner frame 30 is a cam lever 81 biased by means of a spring 82 into a position in which the bifurcated free extremity of the cam lever bears against the periphery of the flange 73. The bifurcated free extremity of the cam lever 81 is formed so as to span the plunger 75 and is formed with an inclined cam surface 83 surmounted by a retaining notch 84 which cooperates with a follower lug 85 on the plunger 75 so as to shift the plunger radially outwardly along the slot 74 into a retracted position in which the plunger is not engageable with the abutment surface 44. The retaining notch 84 in accommodating the follower lug 85 of the plunger 75 determines an at-rest position of the secondary drive member 72 in which at-rest position the drive member will be completely free of and exert no needle positioning influence upon the sewing machine shaft 15.

Carried on the hub portion 71 of the drive member is a pinion 90 which meshes with a rack member 91 which is guided by pins 92 secured in the needle positioner frame 30 and which may also sustain needle bearings 93 therebetween. The rack member 91 is secured by means of a socket member 94 to the piston rod 95 of a conventional spring returned pneumatic cylinder 96 secured on the needle positioner frame 30. The socket member 94 is formed with a cam surface 97 which is adapted to engage the operating arm 98 of an electrical switch 99 carried on the needle positioner frame 30 which, as will be described hereinbelow, serves to determine and control the stroke of the piston rod 95 of the pneumatic cylinder. The pneumatic cylinder is operated by a conventional solenoid operated valve from any convenient pressure source. The solenoid operated valve is illustrated diagrammatically in the electrical diagram of FIG. and indicated thereon as SOL. Reference will now be had to the diagram of FIG. 5 for the following description of the operation of the needle positioning device of this invention.

As illustrated in the diagram of FIG. 5, there exists in the line of a suitable power source a main switch S and across the line the motor M of the power transmitter 16 in series with a control switch S In the circuit for controlling the operation of the needle positioner of this invention, the centrifugal switch 50 and the electrical switch 22 associated with the foot treadle 19 are connected in series with the solenoid operated pneumatic valve SOL and a normally closed set of relay contacts R1 of a relay R. With this arrangement when the treadle 19 is heeled thus closing the switch 22, and the pulley unit 38, 39, together with the sewing machine shaft 15, reaches a stopped condition closing the centrifugal switch 50, the solenoid operated pneumatic valve SOL will be energized to admit operating pressure to the pneumatic cylinder 96. Referring again to FIG. 5, the electrical switch 99 which senses travel of the pneumatic cylinder piston rod 95 is wired together with the relay R in parallel with the solenoid operated valve SOL and the electrical switch 22 across the line. The electrical switch 99 is shunted by a normally open set of relay contacts R-2 of relay R providing for a holding circuit to maintain the relay R energized after the electrical switch 99 is momentarily closed. Upon the completion of the stroke of the piston rod 95 to the point at which the cam surface 97 closes the switch 99, operation of the relay R will open the contacts R-1 and de-energize the solenoid operated pneumatic valve, and the piston rod will be spring returned to bring the drive member back into the at-rest position, as illustrated in dotted lines in FIG. 3, in which the plunger will be retracted by the cam lever 81. Closure of the relay contacts R2 by energization of the relay R will also prevent further operation of the solenoid operated valve SOL until the sewing machine is again operated by the power transmitter so as to effect reopening of the centrifugal switch 50. Each time that the centrifugal switch 50 is opened, the relay R will be de-energized and the relay contacts will revert to their normal position, as illustrated in FIG. 5, readying the circuit for operation of the needle positioner when the sewing machine is thereafter stopped.

During the travel of the rack member 91 in response to operation of the pneumatic cylinder, the drive member 72 will be oscillated approximately one complete revolution from the atrest position during which the plunger 75 will ride off the cam lever 81 thus being released so as to be biased by the spring 76 into a position engageable with the abutment surface 44 on the driven member 36. Regardless, therefore, of the position of the sewing machine shaft 15 when the primary drive from the power transmitter 16 ceases, the plunger 75 will in its complete rotation in response to the operation of the pneumatic cylinder engage the abutment surface 44 and carry the arbor member 36 and pulley unit 38, 39 into a definite position relatively to the needle positioner frame 30 and, therefore, relatively to the sewing machine frame 11. This definite position of sewing machine parts which is affected by operation of the pneumatic cylinder may, of course, be selected by choice of the position of the electrical switch 99 or by choice of the relative position of the clip belt pulleys 39 and 41 on the needle positioner and the sewing machine shaft respectively so as to coincide with any predetermined stopped position of the needle.

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

1. A needle positioning device for a sewing machine having a needle, a rotatable shaft operatively connected to reciprocate said needle, and a primary drive means operatively connected to rotate said shaft, said needle positioning device comprising; secondary driver and driven members, means operatively connecting said secondary driven member for rotation in timed relation with said Sewing machine shaft, and said secondary driven member being formed with a radial abutment, means supporting said secondary driver member for oscillation relatively to said secondary driven member, means defining an at-rest position of oscillation of said secondary driver member, a drive element shiftably supported on said secondary driver member, means urging said shiftable drive element relatively to said secondary driver member into a position engageable with said radial abutment on said secondary driven member during oscillation of said secondary driver member, means effective in the at-rest position of said secondary driver member for retracting and holding said drive element completely out of said engageable position, a secondary drive means operatively connected to impart oscillation to said secondary driver member of predetermined angular amplitude from and back into said at-rest position, and means operable upon a substantially stopped condition of said sewing machine shaft for rendering effective said secondary drive means.

2. A needle positioning device for a sewing unit comprising a sewing machine casing, a supporting table having a top, means supporting said sewing machine casing on said table top, a needle and a rotatable shaft carried in said casing operatively connected to reciprocate said needle, and a primary drive motor carried beneath said table top for rotating said shaft, said needle positioning device comprising a frame, means for supporting said frame beneath said table top, a countershaft journaled in said frame, a pulley unit journaled in said frame, a drive connection between said primary drive unit and said pulley unit, means interconnecting said pulley unit for rotation in timed relation With said sewing machine shaft, a secondary driven member fast for rotation with said pulley unit and formed with a radial abutment, a seconary drive member journaled independently of said pulley unit on said countershaft, a drive element shiftably supported on said secondary drive member, means biasing said drive element relatively to said secondary drive member into a position engageable With said abutment on said secondary driven member, secondary drive means carried by said frame means operatively connected to impart an oscillation to said secondary drive member from and back into a predetermined at-rest position of said secondary drive member relatively to said frame, means effective in the atrest position of said secondary drive member for retracting said drive element out of said engageable position, and centrifugally operated means carried by said pulley unit and responsive to a substantially stopped condition of said pulley unit for rendering said secondary drive means effective.

3. A needle positioning device as set forth in claim 2 in Which said secondary drive means comprises an air cylinder arranged in said frame to partake of a uniform stroke.

References Cited by the Examiner UNITED STATES PATENTS 1,647,148 11/1927 Rosenman 112- 219 1,850,708 3/1932 Davis 112-219 JORDAN FRANKLIN, Primary Examiner. H. H. HUNTER, Assistant Examiner.

Claims (1)

1. A NEEDLE POSITIONING DEVICE FOR A SEWING MACHINE HAVING A NEEDLE, A ROTATABLE SHAFT OPERATIVELY CONNECTED TO RECIPROCATE SAID NEEDLE, AND A PRIMARY DRIVE MEANS OPERATIVELY CONNECTED TO ROTATE SAID SHAFT, SAID NEEDLE POSITIONING DEVICE COMPRISING; SECONDARY DRIVER AND DRIVEN MEMBERS, MEANS OPERATIVELY CONNECTING SAID SECONDARY DRIVEN MEMBER FOR ROTATION IN TIMED RELATION WITH SAID SEWING MACHINE SHAFT, AND SAID SECONDARY DRIVEN MEMBER BEING FORMED WITH A RADIAL ABUTMENT, MEANS SUPPORTING SAID SECONDARY DRIVER MEMBER FOR OSCILLATION RELATIVELY TO SAID SECONDARY DRIVEN MEMBER, MEANS DEFINING AN AT-REST POSITION OF OSCILLATION OF SAID SECONDARY DRIVER MEMBER, A DRIVE ELEMENT SHIFTABLY SUPPORTED ON SAID SECONDARY DRIVER MEMBER, MEANS URGING SAID SHIFTABLE DRIVER ELEMENT RELATIVEELY TO SAID SECONDARY DRIVER MEMBER INTO A POSITION ENGGEABLE WITH SAID RADIAL ABUTMENT ON SAID SECONDARY DRIVEN MEMBER DURING OSCILLATION OF SAID SECONDARY DRIVER MEMBER, MEANS EFFECTIVE IN THE AT-REST POSITION OF SAID SECONDARY DRIVER MEMBER FOR RETRACTING AND HOLDING SAID DRIVE ELEMENT COMPLETELY OUT OF SAID ENGAGEABLE POSITION, A SECONDARY DRIVE MEANS OPERATIVELY CONNECTED TO IMPART

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