US2876722A - Blind stitch sewing machines - Google Patents

Description

March 10, 1959 7 Filed Dec. 20. 1954 WZQETAL F. PARY BLI'ND s'rrrca SEWING MACHINES Fig. l.

2 Sheets-Sheet 1 INVENTOF F ran/r Parry A TTORNE Y March 10, 1959 F. PARRY 2,876,722

BL'IND STITCH SEWING MACHINES" Filed Dec. 20, 1954 2 Sheets-Sheet 2- in '3 E i O a a R, 2 a

o INVENTOR N 5 g m g k. Parry W/TNESS N BY 1/ v g; k 1- I W 5%) A TTORNE Y United States Patent O 2,876,722 BLIND STITCH SEWING MACHINES Frank Parry, Trumbull, Conn., assignor to The Singer Manufacturing Company, Elizabeth, N. J., a corporation of New Jersey Application December 20, 1954, Serial No. 476,143

Claims. (Cl. 112260) The present invention relates to blind stitch sewing machines and has for a primary object to provide means for insuring the proper operative relation between the various elements of the presser mechanism, feeding mechanism and the ridge-forming mechanism, during high speed operation thereof.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those skilled in. the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

Fig. l is a fragmentary front elevation view of a blind stitch sewing machine, the support, and the drive means therefor, to which the present invention has been applied.

Fig. 2 is a fragmentary side elevation view of the device as illustrated in Fig. l but with parts broken away and in section to illustrate better the mechanism of the machine.

As illustrated in the drawing, there is provided a support 1 which comprises the wooden top of a conventional power-table. On the table 1 is a blind stitch sewing machine having a frame comprising a base or base-arm 2, a standard 3 rising from the base, a horizontal upper arm 4' carried by the standard, and a frame-arm 5 carried by the upper arm 4. Depending from the table 1 by means of a bracket 6 is an electric power transmitter 7 having a pulley 8 that is connected by a belt 9 to a pulley 10 that is mounted upon a shaft 1.1 journaled longitudinally of the arm 4 for the purpose of driving the machine.

Blind stitch sewing machines and electric power transmitters are old and well known and since the present co'nstructions are conventional, it is not deemed necessary to expand this disclosure in relation to the details thereof. For a more complete disclosure of the illustrated machine reference may be had to the applicants copending application No. 292,264, filed June 7, 1952, now Patent No. 2,718,862, granted September 27, 1955, and to the disclosures referred'to therein, and fora more complete disclosure of the illustrated transmitter, reference may be had to the patent of Turner, No. 2,597,685, May 20, 1950. The details of the machine and the transmitter are included herein only insofar as is necessary for a complete understanding of the present invention.

The operating mechanisms of the machine include a stitching mechanism comprising the usual curved needle 12 and cooperating looper 13 which are carried by the free end of the frame arm 5. A stationary presser-plate 14 is secured to the frame arm 5'. The feeding mechanism of the machine comprises feed dogs 15 carried by the frame-arm 5 and operating through the usual four-motion cycle. The work is clamped against the resser-plate 14 and is held in opposition to the feed-dogs 15 by a pair of vertically yieldable work-clamping members 16. There is provided a ridge-former 17' which acts in opposition to the presser-plate 14 in the formation of ridges in the Work for penetration by the needle 12. The Work-clamp- .ing, member 16 and the ridge-former 17 are carried by a .work-table 18 having depending side-walls 19. The worktable 18 is pivotally mounted upon the ends of a shaft that extends through the side-walls 19 and through spaced upstanding lugs 21 integral with a bracket 22 secured to the base 2. The Work-table 18 is pivotally urged about the shaft 20 in a counterclockwise direction by a coil compression spring 23 which encircles a rod 24 arranged beneath the table 1, the spring 23 acting between a bracket 25 secured to and depending from the table 1 and a nut 26 threaded onto the rod and constituting an adjustable abutment for the one end of the spring. In the usual manner, although not herein illustrated, it is intended that stop means be provided to limit the pivotal movement of the work-table 18 to its normal operative position, such means being illustrated, for example, in applicants above noted Patent No. 2,718,862. The rod 24 is pivotally connected at 27 to the lower end of a lever 28 that is prm vided with an ear 29 fitted into a slot 30 in the front wall 31 of the work-table 18, a pivot screw 32 in the front wall 31 passing laterally through the slot 30 and through the ear 29. The lever 28 is thereby pivoted to the worktable 18. The upper end of the lever 28 abuts against the inner surface of the front wall 31 of the work-table whereby the lever 28 is operatively connected to the work-table 18 for biasing the same upwardly about the pivot shaft 20 into operative position under the action of the spring 23. A slot 33 in the table 1 provides clearance for the lever 28.

In operation, the spring 23, through the rod 24 and lever 28, pivotally biases the Work-table 18 about its pivot 20 in a counterclockwise manner, as seen in Fig. 2, and thereby biases the work-clamping members 16 and ridgeformer 17 which are carried by the work-table 18 upwardly into operative relation with the resser-plate 14 and the stitching and feeding mechanisms carried by the frame arm 5. As is usual during operation, the action of the feeding mechanism and the action of the ridge-forming mechanism tend to depress the work-table 18 against the bias of the spring 23, and under high speed operation the inertia forces tend to prevent recovery of the elements under the action of the spring 23. It is, therefore, necessary that the spring 23 be large enough to effect recovery of the parts under the designed maximum operating speed. However, the work-table 18 must be manually depressed to provide for the introduction of work, which is accomplished by means of a manually actuated rod 34 pivoted in a bracket 35 secured to the base 2 and having a crank 36 connected by a wire link 37 to the rear edge of the work-table 18. Under very high speed operation, the spring 23 must be made so large that it is diflicult and very tiring repeatedly to lower the work table. In accordance with the present invention, there is provided a fluid pressure means similar to that disclosed in the copending application of Odermann et al., Serial No. 312,934 filed October 3, 1952, now Patent No. 2,750,908, granted June 19, 1956, which means will increasethe force biasing the work-table 18 upwardly into operative position as the speed of operation of the machine is increased, thereby permitting the use of a relatively light spring which will facilitate manual lowering of the worktable 18 but which will also provide the necessary force for holding the work-table in operative position during high-speed operation of the machine.

In the disclosed preferred embodiment of the invention, the fluid pressure means is penumatic. The transmitter 7 is provided with a pump 38 connected to the pulley 8, which pump is of the type in which the pressure of the air delivered is in direct proportion to the speed of operation of the same, such as a rotary vane type pump. The pump which is more fully described in the copending application of I-lappe, Serial No. 134,958, filed December 24, 1949, now Patent No. 2,721,692,

granted October 25, 1955, comprises a housing 39 fixed by support.

nected to the discharge outlet 44 of the pump is a pressure relief valve 45 such as disclosed in the above-noted Patent No. 2,750,908, which limits the maximum air pressure in the system.

A hose fitting 46 is provided at the outlet of the valve 45 and is connected by a hose 47 to a similar'fitting 48 at the inlet of a fluid pressure motor, which, in that the preferred embodiment of the invention is pneumatic, comprises an air cylinder 49. A cover-plate 50 is socured to the air cylinder for closing the open end thereof and also for supporting the same. A supporting bolt 51 passes through the cover-plate 50 and is clamped thereon by a lock nut 52. The end of the bolt 51 passes through an aperture in a stud 53 carried by a bracket 54 depending from the table 1 and is secured in longitudinally adjusted position relatively to. the stud 53 by a pair of lock nuts 55. The air cylinder 49 is thereby adjustably supported by the table 1.

The rod 24 extends into the air cylinder 49 through v a bushing 56 and within the cylinder has secured thereon by means of a pair of lock nuts 57, a piston 58 comprising spaced circular piston discs 59 having a flexible packing disc 60 arranged therebetween. Thus, as pressure is introduced into the air cylinder 49 through the inlet 48, the piston 58 is urged toward the right as seen in Fig. 2, which will exert a pull upon the rod 24 that acts in addition to the pull exerted by the spring 23 to increase the force biasing the work-table 18 in a counter clockwise direction about its pivot 20. Since the operation of the pump 38 is such that the output pressure varies in a direct proportion to the'speed of operation thereof, the effective actionof the piston 58 upon the rod 24 will increase as the operating speed of the machine increases, thus overcoming the increased inertia forces which also accompany increased operating speeds. The effective action of the spring 23 can be adjusted by means of the nut 26, while the piston 58 can be adjusted by bodily adjusting the air cylinder 49 relatively to its Having described the invention, what is claimed is: 1. In a sewing machine, a support, a blind stitch sewing machine mounted upon said support and having a worktable movable relatively to said support toward and away from an operative position, drive means depending from said support and operatively connected to said sewing machine for driving the same, a first means connected to said. worktable for moving the same toward operative position, and a second means including fluid pressure means operatively connected to said work-table for augmenting said first means in moving said work-table toward operative position, said fluid pressure means comprising a pump operatively connected to said drive means for generating a fluid pressure in direct proportion to the speed of operation of said drive means and a fluid 'motor operatively connected to said work-table, and fluid delivering connections between said pump and motor.

2. In a sewing apparatus, a support, a blind stitch sewing machine mounted upon said support and having a tiltable work-table journaled on an axis in a plane parallel to and spaced from said support, drive means depending -from said support and operatively connected to said sewing machine for driving the same, fluid pressure generating means operatively connected to said drive means for producing a fluid pressure in direct proportion to the speed of operation of said drive means, manually actuated means for depressing said work-table from operative position, resilient means for urging said worktable upwardly into operative position, fluid pressure responsive means acting in addition to said resilient means for biasing said work-table into operative position, and

operative connections between said fluid pressure generating means and said fluid pressure responsive means .for varying in direct proportion to the speed of operation of the machine the action of said fluid pressure re- .4 sponsive means urging said worletable into operative position.

3. In a sewing apparatus, a support, a blind stitch sewing machine mounted upon said support and having a tiltable work-table journaled upon an axis in a plane parallel to and spaced from said support, drive means depending from said support and operatively connected to said sewing machine for driving the same, resilient means for biasing said work-table into operative position, means for moving said work-table from operative position, and fluid pressure means for varying the bias of said work-table toward operative position in accordance with'the sewing speed, said fluid pressure means comprising a fluid pump operatively connected to said drive means for generating a fluid pressure in direct proportion to the sewing speed, fluid motor means operatively connected to said work-table and acting in conjunction with said resilient means to vary the bias of said work-table, and fluid connections between said pump and motor.

4. In a sewing apparatus, a support, a blind stitch sewing machine mounted upon said support, said machine having a frame including a frame-arm and a tiltable worktable journaled in said frame on an axis parallel to and spaced from said support, complementary stitch-forming instrumentalities carried by said frame-arm and worktable, a presser plate carried by said frame arm, presser from operative position, fluid pressure responsive means operatively connected to said work-table and acting in conjunction with said resilient means for varying the biasing force applied to said work-table, and operative connections between said fluid pressure generating means and said fluid pressure responsive means for varying the action of the latter in direct proportion to the speed of operation of the machine.

5. In a sewing apparatus, a support, a blind stitch sewing machine mounted upon said support and having a tiltable work-table journaled upon an axis in a plane parallel to and spaced from said support, drive means depending from said support and operatively connected to said sewing machine for driving the same, manual means for moving said work-table from operative position, and means for biasing said work-table into operative position comprising a lever depending from said work table, a longitudinally movable rod arranged beneath said support and connected to said lever, resilient means longitudinally biasing said rod and thereby biasing said work-table into operative position, and fluid pressure table in accordance with the sewing speed, said fluid pressure means comprising an air pump operatively connected to said drive means for generating a pressure in direct proportion to the sewing speed, a fluid pressure motor comprising an air cylinder secured to the under side of said support, said rod extending into said air cylinder and having secured thereto within said air cylinder a piston, and connections between said pump and said motorwhereby said motor will act in conjunction with said resilient means to increase the biasing force applied to said work-table for moving the same toward operative position as the sewing speed is increased.

References Cited in the file of this patent UNITED STATES PATENTS 1,764,573 Mueller June 17, 1930 2,527,353 Christian Oct. 24, 1950 2,541,888 Pinkvoss Feb. 13, 1951

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