US3168066A

US3168066A - Needle-positioning mechanism for powerdriven sewing machines and the like

Info

Publication number: US3168066A
Application number: US236548A
Authority: US
Inventors: Hedegaard Kristen
Original assignee: GM Pfaff AG
Current assignee: GM Pfaff AG
Priority date: 1961-11-14
Filing date: 1962-11-09
Publication date: 1965-02-02
Anticipated expiration: 1982-02-02
Also published as: DE1145465B; CH399149A

Description

3,168,966 Patented Feb. 2, 1965 28,22 8 Claims. (Cl. 112-219) The present invention relates to needle-positioning mechanism for power-driven sewing machines and more particularly to apparatus for stopping a reciprocating needle in a predetermined position of its operating cycle. In the operation of a conventional power-driven sewing machine it often is desirable to stop the machine with the needle being in a predetermined position, such as the up or down position relative to the work being sewn. As an example, stopping in the up position is desirable when threading the needle or for changing the position thereof in the fabric, and the down position is desirable for turning the fabric without removing the needle therefrom. The desired positions may be adjusted manually in a known manner by turning the balance wheel after the power drive has been disconnected or the machine brought to a standstill.

In order to effect the stoppage of a sewing machine at a precisely defined needle position without shock or vibration and in order, furthermore, to enable the instant of stoppage to be preselected at will during the sewing operation, complex and expensive mechanism is required in utilizing the heretofore known stopping devices and methods. There have also become known needle-positioning devices of a less complex nature by which the stoppage of the machine is effected by first disconnecting the driving motor by the opening of an electric switch controlled by way of the linkage mechanism associated with the conventional foot pedal control, whereupon an abutment plate or stop is advanced into or toward the path of a positioning pin rotating with the drive shaft of the machine by means of a cam and follower arrangement mounted below the sewing plate or bed of the machine.

With sewing machines thus equipped it is not possible to effect stoppage of the machine at an exactly defined position of the needle, inasmuch as the stoppage may occur within an angle greater than 180. As a consequence, the thread take-up lever of the machine may assume such an unfavorable position within this angle of the drive shaft as to impede or prevent the ready pulling of the thread. Besides, with the abutment plate being ordinarily fitted with a nose or projection deflecting, in the lower dead end position of the needle bar, the positioning pin rotating with the drive shaft of the machine, there exists the further danger of upper thread penetration into the path of the loop taker, in that the machine may rotate in a direction opposite to its normal operating direction as a result of the deflection of the positioning pin.

Other known needle positioning devices involve the stoppage of the machine at a random position followed by renewed rotation of the driveshaft and displacement of a stop or abutment member into the path of a drag or braking member rotating together with said shaft, in such a manner as to arrest the machine at a predetermined position of said shaft and, in turn, of the needle. Again, in order to carry out the various operations by the actuation of a single control device or member, complex and expensive control apparatus occupying considerable mounting space is required.

Finally, sewing machines have become known being fitted with a stoppage device, whereby the machine, after having been arrested at a random position in the ordinary manner, is restarted and rotated until after the needle has reached a predetermined position, whereupon the final stoppage of the machine is effected by mechanical control means or apparatus. If, in the case of machines of this type, it is desired to continue the ordinary sewing, upon stoppage by the automatic mechanism, a manual lever arranged at the rear of the machine and connected with a control cam must first be operated to a predetermined position in order to retract the mechanical abutment out of the way of the brake or drag element forming part of and usually being mounted upon the balance wheel of the sewing machine. In order subsequently, that is, after completion of the sewing operation to re-start or rotate the machine having been stopped at a random position until the needle assumes its predetermined position and to arrest the machine by the mechanical stopping means, renewed operation of the manual lever is required be fore the final stoppage of the machine may be elfected by means of a further control lever. In other words, the operation of two levers is required for the initiation of a stopping operation, one of said levers being mounted at the rear of the machine for lack of other mounting space, a position most unfavorable from an operating standpoint.

Accordingly, an important object of the present invention is the provision of control apparatus for the automatic stopping of a sewing and the like machine at a predetermined, preferably selectable, angular position of the drive shaft of the machine, that is, coinciding with a predetermined needle position of a sewing machine, by which the foregoing and related difficulties and drawbacks are sub stantially eliminated and stoppage of the machine at the predetermined position may be effected simply by the operation of a single lever or the like control member.

Another object of the invention is the provision of improved needle-positioning means for a power-driven sewing machine of the type referred to by which stoppage of the machine and positioning of the needle may be achieved reliably and expeditiously by the operation of a single actuating key or the like control member, after disconnection of the driving motor and stopping of the machine at a random position.

Yet another object of the invention is the provision of needle-positioning apparatus for power-driven sewing machines of the type referred to which is both compact and Will require a minimum of parts and mounting space, and which can be readily structurally combined with conventional sewing machine designs or constructions.

A more specific object of the invention is the provision of needle-positioning apparatus for a power-driven sewing machine, whereby upon stopping of the drive shaft of the machine by disconnection of the electric drive and with the needle being at a random position, actuation of a single stopping lever or the like control member will result in the sequential operations of restarting the driving motor by closing an auxiliary switch, interrupting said circuit and thereafter braking and arresting of said shaft, to bring the machine to a full stop at a position corresponding to a predetermined needle position.

Still another object of the invention is the provision of needle-positioning means for power-driven sewing machines of the type referred to which lends itself simply and readily to the selective stopping or positioning of the needle at any one of a desired number of plural stopping positions within a full stitching or needle operating cycle.

The invention, both to its ancillary objects as well as novel aspects, will be better understood by the following detailed description, taken in conjunction with the accompanying drawing forming part of this specification and in which:

FIG. 1 is a perspective view of a conventional sewing 3 machine, shown partly in' section and embodying the improvements accordingto'the present invention;

FIG. 2 is a perspective view, shown on an enlarged scale and with parts being broken away, of the angular position control mechanism according to the invention embodied in the machine shown by FIG. 1; and

FIG. 3 is an electric wiring diagram of the stoppage device of the invention.

Like reference numerals denote like parts inboth views of the drawing.

With foregoing objects in view, the invention involves generally the provision of angular position control apparatus comprising a single control member, such as a key, lever, etc., being normally urged to an inoperative position by a biasing spring or the like, said member adapted to operate an electric switch, controlling the driving motor for the shaft to be adjusted or positioned, such as the arm shaft of a sewing machine, between ON and OFF positions by actuation of said member from an inoperative to an operative position, and vice versa, against and by release by said spring, respectively. There is further provided according to the invention a control cam carried by said shaft being disengaged from said member I in its normal position and having a first peripheral radial projection of relatively low height and adapted to engage a shoulder or the like abutment of 'said member in the operative position, to operate said switch, having previously been closed upon operation of said member to its OFF position, to thereby disconnect said motor. Said control cam is furthermore provided with a second radial projection located at a predetermined angular position relative to said shaft and having a relatively greater height than and following said first projection in the rotating direction of said shaft, in such a manner as to brake said shaft to a full stop by engagement with said member after disconnection of said of said cam.

If desired, a plurality of control members or levers may be provided in juxtaposed position each adapted to control said switch in the manner described and cooper ating with a different one of a plurality of coordinated control cams carried by said shaft and having angular positions relative to said shaft for the positioning thereof and, in turn, of the needle of a sewing machine at predetermined selectable positions by actuation of the respective plural control members. i

There is thus provided by the invention angular position control apparatus, whereby actuation of a single control lever or the like control means causes the driving motor of the shaft to be set into motion while at the same time a shoulder or abutment of said lever is operated towards or into the-path of a control cam and braking device mounted upon said shaft and designed to sequentially stop the motor to arrest said shaft and to brake the same to a full stop at a predetermined angular position, by the simple depression of an actuating key or the like control member.

In the operation of modern sewing machines, it is desiraole to arrange the operating devices forthe stoppage of the machine in the field of view of the operator and at a favorable position to facilitate the operation'and control of the machine. Besides, the control device should require a minimum of mounting space on account of the available limited free space in conventional sewing machines already burdened with numerous auxiliary devices, such as zigzag or ornamental stitching attachments and the like. This aim may be achieved in a most simple manner by the invention by mounting the control cam or cams upon the main drive or arm shaft of the machine and at a position close to the crank driving the reciprocating needle bar, that is, between the latter and the front bearing of said shaft, as will be further described in the following.

As is understood, in the case of needle-positioning apparatus according to the invention, any number of con-' motor by the first projection trol members may be provided in conjunction with a corresponding number of control cams, to selectively stop the needle at any of a desired number of preselectible positionswithin its operating cycle. As an example, besides the up and down positions, the needle may be stopped, by the proper design of the control cam or cams, at any desired intermediate position suitable for the cutting of the upper or lower threads, or to suit any other conditions or operating requirements. All that is required, to achieve this aim, is the proper angular positioning of the respective control cam or cams, in a manner readily understood and becoming further apparent as the following description proceeds with reference to the drawing.

Referring to the latter, the numeral 1 represents the base of a conventional sewing machine supporting the upper arm or casing 2 which terminates in the sewing head 3. An electric driving motor 4 mounted within the base 1 serves to rotate the arm or drive shaft 8 mounted within the arm 2 by means, according to the example shown, of a first sprocket 5 connected to the motor shaft, a'belt or driving chain 7 and a second sprocket 6 or the like mounted upon the shaft 8. Further mounted upon the front end or the shaft 8 is a crank 9, FIG. 2, which serves to reciprocate the needle bar 10 through a suitable link (not shown), in a manner well in the construction of conventional sewing machines.

Rotatably mounted, in the example shown, about a pin or pivot 12 supported by a bracket 11 being secured to the casing 2 is a pair of juxtaposed

operating levers

13 and 14, shown in the form of bellcrank levers in the drawing and each having a shoulder or abutment 15 and carrying a

control key

16 and 17, respectively, at its front end projecting outwardly from the casing 2 through an opening or slot 18, FIG. 1. The

keys

16 and 17 may be provided with suitable indicia, such as identifying the up and down positions of the needlebar 10 or needle car ried thereby. The opposite and angularly bent

arms

19 and 20 of the

levers

13 and 14 are arranged to cooperate with an electric switch or relay21 inserted in the circuit of or controlling the driving motor 4, in such manner as to close the-motor circuit and to initiate rotation of the shaft 8 'upon either of the keys 16'a11d 17 being depressed against the action of suitable biasingsp-rings 24 or the like and to disconnect the motor by opening of the switch 21 upon release of the keys by the'action of the springs 24. The springs 24 encircling a guide post 23 mounted upon the casing 2 are arranged with one of their ends engaging a bore in said casing and with their opposite ends engaging the undersurface of the

respective levers

13 and 14, this arrangement shown by way of example being subject to modifications, as will suggest themselves to those skilled in the art.

Arranged in alignment with the

levers

13 and 14 and between the needle bar crank 9 and the front bearing 25 of the shaft 8 being supported by the bracket 11 are a pair of

cam disks

26 and 27 each having a keyway 28 engaged by an adjusting spring 28 mounted upon the shaft' 8, to cause said disks to rotate together with said shaft.

Each of said cam disks is provided upon its periphery with f a pair of juxtaposed

radial projections

30, 31 and 32, 33 respectively, said projections having heights increasing in the rotating direction of the disks, that is, with the

projections

30 and 32 having a relatively low height and with the projections '31 and 33 having a relatively greater height and closely following the former projections, in the manner shown in the drawing; The

projections

30 and 32 of the

disks

26 and 27. are so. dimensioned as to cooperate with the abutment or shoulders 15 of the

levers

13 and 14, in the depressed position of the levers, Whereby to lift said levers, against the digital pressure exerted by the operator in holding down the

keys

16 or 17, respectively, and to interrupt the switch 25 having been previously closed by the depression of said keys. The

projections 31and 33 of the disks .26 and 27, on the other hand, are dimensioned such as to impart a drag or braking force upon the cams or disks and, in turn, upon the shaft 8 immediately following the disconnection of the driving motor, in such a manner as brake the shaft and with it the needle of the sewing machine to a full stop at a precisely predetermined angular position defined by the position of the

projections

31 and 33, in a manner as will be readily understood. In the example shown for stopping a sewing machine with the needle in either the up or down position, the

projections

30, 31 and 32, 33 are disposed diametrically opposite to one another, it being understood that the position of the cam or cams may be changed for stopping of the machine in any other angular position, or that additional control levers and cooperating control cams may be provided, to afiord a selective stoppage or postioning of the needle at any of a number of predetermined positions within an operating or stitching cycle.

FIG. 3 shows the wiring diagram of the stoppage device of the invention. One terminal of a supply source (electric power line, etc.) is connected to the first pole of the motor 4 through a lead 34 and the second terminal of said source is connected to the second pole of said mo tor through a lead 35, a conventional starting resistance 36, contact 37 and lead 38. Contact 37 being normally in the open position cooperates in a known manner with the resistance 36 during operation of a starter pedal or the like control device (not shown), to apply operating voltage to and control the speed of the motor 4. A suitable tap point of the resistance 36 is connected through a lead 39 with a first contact 40 of the switch 21, contact 40 being connectible by the contact arm 21 with a cooperating switch contact 41 which is connected to the second pole of the motor 4. As a consequence, closing of the contacts 40 and 41 by either of the

lever arms

19 or 20 will result in a reduced operating voltage being applied to the motor 4 via the resistance 36, whereby to operate the motor at reduced speed for the carrying out of the positioning or stoppage operation in the manner described hereinafter.

In operation, the driving motor 4 of the sewing machine is energized by means of the

starting switch

36, 37, to drive the machine via the sprockets 5, 6 and chain '7. In order to interrupt the sewing operation, the starter is returned to its initial position, FIG. 3, whereby to cause a stoppage of the machine at a random angular position of the shaft 8 and, in turn, of the needle bar 10. As pointed out, it may be required, for instance, to stop the needle in the up position for the removal of the work, or to stop the needle in the down position for turning of the work, or for any other reason, while other stopping positions may be desirable or required to suit any conditions and operating requirements.

For the latter purpose, all that the operator has to do, after the initial stoppage of the machine at a random position, is to depress the

proper key

16 or 17, to rotate the

respective lever

13 or 14 about the pin or pivot 12 and to thereby cause the

end

19 or 20 to actuate the switch 21 connecting the motor and restarting the rotation of the shaft 8 at reduced speed by closing the contacts 40 and 41. Simultaneously with the operation of the switch 21, the shoulder of the depresesd lever slidably engages the circumference of the

respective disk

25, 27, while the shaft 8 continues to rotate. As soon as the

lower projections

30 or 32 engage the shoulder 15, the end 19 or of the

levers

13 or 14 is withdrawn from the switch, thus interrupting the latter and disconnecting the motor 4. The latter, and with it the shaft 8 continue to run on account of their kinetic energy, until the

second projection

31 or 33 acting as a drag or brake engages the shoulder 15, whereby to brake the motor and with it the shaft 8 to a full stop at an angular position determined by the angular position of the projections of disks 2s and 27, respectively. At the same time, the needle will be in the desired position, such as the up or down position, or any other intermediate position, depending upon the design of the cams. After the shaft or needle have been positioned in this manner, the operator releases the key 13 or 14 to cause the same to be returned to its starting position by the springs 24, or out of engagement with the cams 26- or 27, respectively.

In the foregoing the invention has been described with reference to a specific illustrative device. It will be evident, however, that variations and modifications, as well as the substitution of equivalent elements or parts for those shown herein for illustration, may be made without departing from the broader scope and spirit of the invention, as set forth in the appended claims. The specification and drawing are accordingly to be regarded in an illustrative rather than in a limiting sense.

I claim:

1. In a power-driven sewing machine including a reciprocating needle, a drive shaft and means to operate said needle by said shaft, and an electric motor to drive said shaft, needle positioning apparatus comprising in com bination:

(1) a control member,

(2) resilient means to normally urge said member to an inoperative position,

(3) a control cam upon said shaft for cooperation with said member being disengaged from said member in said inoperative position,

(4) electric switch means controlled by said member, to connect said motor by closing said switch means upon operation of said member from said inoperative position to an operative position of engagement with said cam against the action of said resilient means,

(5) said cam having a first radial projection of relatively low height and adapted to engage and operate said member to open said switch means, and

(6) said cam having a second radial projection at a predetermined angular spacing from said first projection, said second projection being of relatively greater height than and following said first projeciion in the direction of rotation of said shaft, where- (7) to brake said shaft to a full stop upon engagement of said member by said second projection after disconnection of said motor by said first projection, while maintaining said member in said operative position.

2. In needle-positioning apparatus as claimed in claim 1, comprising a plurality of juxtaposed control members each arranged to actuate said switch, and a plurality of cams upon said shaft each arranged for cooperation with one of said members and having projections being differently angularly oriented, for selectively positioning said needle at different predetermined positions by operation of said members.

3. In needle-positioning apparatus as claimed in claim 1, said member being comprised of a double lever having one spring-loaded arm terminating in an operating key and having its opposite arm arranged to actuate said switch.

4. In needle-positioning means as claimed in claim 1, comprising a plurality of juxtaposed control members in the form of spring loaded levers each arranged to actuate said switch and projecting outwardly from the upper arm of the sewing machine, and a plurality of cams carried by said shaft within said arm adjacent to the needle bar driving crank, each of said cams being arranged for cooperation with one of said levers and having projections being differently angul-arly oriented relative to said shaft, for selectively positioning said needle at different predetermined positions by actuation of said levers.

5. In a power-driven sewing machine including a reciprocating needle, a drive shaft and means to operate said needle by said shaft, and an electric motor to drive said shaft, needle positioning apparatus comprising in combination:

(1) a manually operable control lever having a shoulder and terminating in an operating key,

(2) resilient means to normally urge said lever to an inoperative position,

(3) a control cam upon said shaft being in line with said lever and disengaged therefrom in said inoperative position,

(4) an electric switch controlled by said lever, to connect said motor by closing of said switch upon operation of said lever from said inoperative position to (7) to brake said :shaftto a full stop upon said shoulder engaging said second projection after diseonnection of said motor by said first projection, while maintaining said lever in said operative position. 1

6. In needle-positioning apparatus as claimed in claim 5, comprising a plurality 'of juxtaposed control levers each arranged .to actuate said switch, and a plurality of control cams mounted upon said shaft and each arranged for cooperation with one of said levers, said cams having projections' ditferently angularly oriented relative to said shaft, for stopping said needle at different predetermined positions within its operating cycle by selective operation of said levers.

7. In combination with a rotating shaft and an electric motor to drive said shaft, angular positioning means ccmprising: V

(1) a control member,

(2) resilient means to normally urge said member to an inoperative position, i

.23 (3) a control cam upon said shaft for cooperation with said member being disengaged from said member in said inoperative position, (4) an electric switchcontrolled by'said member, to 5 connect said motor by closing said switch upon operation of said member from its inoperative position to an operative position of engagement with said cam against the action of said resilient means,

(5) said cam having a first radial projection of relatively low height adapted to engage and operate said member toward said inoperative position, to thereby disconnect said motor by opening said switch, and

(6) said camihaving a second radial projection at a predetermined angular spacing from said first projec tion, said projection being of relatively greater height than and following said first projection in the direction of rotation of said shaft, whereby 7) to brake said shaft to a full stop upon engagement of said member by said second projection after disconnection of said motor by said first projection, while maintaining said member in said operative position.

8. In angular positioning apparatus as claimed in claim 7, comprising a plurality of juxtaposed control members each arranged to actuate said switch, and a plurality of cams upon said shaft each arranged for cooperation with one of said members and having projections being differently angulairly oriented, for stopping said shaft at different predetermined angular positions by selective operation of said members.

References Cited by the Examiner UNITED STATES PATENTS 1,265,986 5/18 Ashworth i12 '219 X 2,612,127 9/52 Hayes "112-219 2,921,547 1/60 Artz'tet a1. 112 219 FOREIGN PATENTS 885,340 1 8/53 Germany. JORDAN FRANKLIN, Primary Examiner.

DAVID I. WTLLIAMOWSKY, ROBERT v. SLOAN,

' I Examiners.

Claims

1. IN A POWER-DRIVEN SEWING MACHINE INCLUDING A RECIPROCATING NEEDLE, A DRIVE SHAFT AND MEANS TO OPERATE SAID NEEDLE BY SAID SHAFT, AND AN ELECTARIC MOTOR TO DRIVE SAID SHAFT, NEEDLE POSITIONING APPARATUS COMPRISING IN COMBINATION: (1) A CONTROL MEMBER, (2) RESILIENT MEANS TO NORMALLY URGE SAID MEMBER TO AN INOPERATIVE POSITION, (3) A CONTROL CAM UPON SAID SHAFT FOR COOPERATION WITH SAID MEMBER BEING DISENGAGED FROM SAID MEMBER IN SAID INOPERATIVE POSITION, (4) ELECTRIC SWITCH MEANS CONTROLLED BY SAID MEMBER, TO CONNECT SAID MOTOR BY CLOSING SAID SWITCH MEANS UPON OPERATION OF SAID MEMBER FROM SAID INOPERATIVE POSITION TO AN OPERATIVE POSITION OF ENGAGEMENT WITH SAID CAM AGAINST THE ACTION OF SAID RESILIENT MEANS, (5) SAID CAM HAVING A FIRST RADIAL PROJECTION OF RELATIVELY LOW HEIGHT AND ADAPTED TO ENGAGE AND OPERATE SAID MEMBER TO OPEN SAID SWITCH MEANS, AND (L) SAID CAM HAVING A SECOND RADIAL PROJECTION AT PREDETERMINED ANGULAR SPACING FROM SAID FIRST PROJECTION, SAID SECOND PROJECTION BEING OF RELATIVELY GREATER HEIGHT THAN AND FOLLOWING SAID FIRST PROJECTION IN THE DIRECTION OF ROTATION OF SAID SHAFT, WHEREBY (7) TO BRAKE SAID SHAFT TO A FULL STOP UPON ENGAGEMENT OF SAID MEMBER BY SAID SECOND PROJECTION AFTER DISCONNECTION OF SAID MOTOR BY SAID FIRST PROJECTION WHILE MAINTAINING SAID MEMBER IN SAID OPERATIVE POSITION.