US2232692A - Electromagnetic sewing machine - Google Patents

Description

Feb. 25, 1941. F. DIEHL ELECTROMAGNETIC SEWING MACHINE Filed Jan. 9, 1940 3, Sheets-Sheet 1 rederick Feb. 25, 1941. F. DIEHL ELECTROMAGNETIC SEWING MACHINE Filed Jan, 9', 1940 3 Sh'ots-Shept 2 ii'egderick Dielzl Feb. 25, 1941. F. DlEHL ELECTROMAGNETIC SEWING MACHINE 3 Sheets-Sheet 3 Filed Jan. 9, 1940 B I J J o a H...., W Ma Q ,9 m. 7 5

3 m MMQF mflmd 6/ v u J v o a WK 7 AW w m 4 \l/llll d o r W h Patented Feb. 25, 1941 ELECTROMAGNETIC SEWING MACHINE Frederick Diehl, Elizabeth, N. J., assignor to The Singer Manufacturing Company,

N. J a corporation of Elizabeth, New Jersey Application January 9, 1940, Serial No. 313,023

8 Claims.

This invention relates to sewing machines and has for an object to provide a sewing machine with improved electromagnetic means for operating one or more of the component mechanisms of the machine, so that all mechanical connections between such mechanism and the other component mechanism or mechanisms of the machine may be eliminated.

The aims in view are attained by operating a selected one of the component mechanisms of the machine by means of a specially constructed solenoid having a movable core of lightweight which may be given controlled series of impulses or steps between its extreme positions. Preferably, the present solenoid is applied to the endwise reciprocatory needle-bar of the sewing machine to eliminate all mechanical connections from the overhanging bracket-arm of the machine. By means of the present solenoid, the needle-bar is caused to descend in a plurality of steps, pause in its lower position for seizure of the needle-thread loop by the loop-taker, and subsequently rise in a plurality of steps to the limit of itsupstroke.

In the accompanying drawings Fig. 1 is a side elevation, partly in section, of a sewing machine embodying the invention. Fig. 1 is a. sectional view of the needle-bar-operating solenoid of Fig. 1, with the core piece or armature in a position intermediate its extreme positions. Fig. 2 is a bottom plan view of the machine. Fig. 3

solenoid. Fig. 4 is a plan view of the end-portion of the machine-bed underlying the needlebar. Fig. 5 is a section on the line 55, Fig. 2. Fig. 6 is a sectionon the line 5B, Fig. 2. Fig. 7 is a section on the line 1-1, Fig. 2. Fig. 8 is a' vertical section taken longitudinally of the machine-bed through the axis of the loop-taker which is about on the line 8-8, Fig. 4. Fig. 9 is a diagrammatic illustration of the movements of the needle-bar and loop-taker over one complete stitch-forming cycle. Fig. 10 is a diagrammatic illustration of the circuit containing the several sections or energizing coils of the solenoid and their controlling switches and Fig. 11 is a development of the cam-cylinder which operates the solenoid-controlling switches.

The machine is constructed with a frame including the fiat rectangular bed I from one end of which rises the standard 2 of the overhanging bracket-arm 3 terminating in the head 4 which carries the three-coil solenoid s for operating the needle-bar 5 and needle 6.

The solenoid s comprises the inner brass tube 1 on which are tightly press-fitted the steel disks 8, 9, Ni, H, which are equally spaced apart by the intervening Bakelite insulating sleeves 12 to provide winding spaces for the magnet wire coils I3, l4 ,l5 all of which are preferably wound in the same direction so as to have the same polarity. After the magnet wire coils are wound between the equally spaced disks 8, 9, III, II, a cylindrical steel shell I8 is tightly fitted to the peripheral edges of the disks. End-caps ll, I8 of non-magnetic material, such as aluminum, are fitted tothe ends of the shell l6 and held by screws l9 which enter the top'and bottom disks 8 and II.

This complete unitary solenoid assembly s is fitted to a seat 20 in the head 4 and fastened to said seat by screws 2| so as to be rigid with said head 4 and bracket-arm 3. The top end-cap I1 is fitted with a top bearing bushing 22 for the needle-bar 5 the bottom bearing 23 for which is in the lower end of the head 4. The bottom end-cap I8 of the solenoid s, is formed with a needle-bar clearance opening 24.

The needle-bar 5 has fixed thereto, within the solenoid core tube I, a comparatively short steel core-cylinder or armature 25 of lightweight. The armature 25 is of a length to reach approximately from the plane of the bottom face of the solenoid disk 8 to the plane of the top face of the solenoid disk III, as shown in 1*. When one of the magnet coilsis energized by a mediately adjacent the energized coil become magnetized and present annular magnetic poles of opposite polarity at their central apertures. These poles will draw the armature 25 to a position bridging the gap between such poles, as shown in Fig. 1. When two adjacent magnet coils are simultaneously energized the steel disk immediately above the upper coil and the steel disk immediately below thelower of the two-energized coils will preseniaannular magnetic poles of opposite polarity. l The intermediate steel disk will have no polarity-and the armature 25 will shift its position one step, as from. that shown in Fig. 1 to that shown in Fig. 1, so that it will bridge the gap between the disks 8 and I. On the downstroke of the needle-bar the magnetwire coils are preferably energized in the following sequence: beginning with coil l3 energized, the next step is to energize coil l4 while maintalning coil l3 energized. This causes the needie-bar to descend one'step or from the position shown in Fig. 1 to the position shown in Fig. 1. Following this step the coil I3 is de-energized direct current of electricity, the steel disks im- I whereupon the needle-bar descends another step so that the armature will bridge the gap between disks 9 and M. For the third step in the descent of the needle-bar, coil I5 is energized while maintaining the energization of coil l4. Finally, coil I4 is de-energlzed and theneedle-bar makes the last step of its downstroke. Thus, the armature 25 and needle-bar 5 may be made to travel by short stages or steps from one extreme position to the other, by. energization and de-energization of selected magnet coils at the proper times, as will be evident to those skilled in the art. Cushioning washers 28 of felt, cork or the like are preferably provided .within the endcaps l1, l8 to yieldingly and qu etly limit the endwlse movements of the armature 25 and neodle-bar 5.

The needle-bar 5 has fixed thereto a block 21 which pivotally carries the needle-thread takeup lever 28 having a thread take-up eye 29. The lever 28 has a bifurcated tail 30 which engages the stationary pin 3|. The take-up lever 28 has a curved extension 32 beyond the thread-eye 29 which serves as a guard to prevent the slack needle-thread from looping over the top-edge of the lever 28 when the latter drops to give slack to the needle-thread for the loop-casting excursion of the oscillatory hook or loop-taker to be described.

Slidably mounted in the head 4, behind the needle-bar 5, is the hollow resser-bar 32 carrying the presser-foot 33. The presser-bar 32 houses a presser-spring 34 engaged at its upper end by the lower end of the adjustable screw-pin 35 the head 36 of which is threaded into the frame-lug 31. The presser-bar has fixed to its upper end the block 38 which is engaged by the usual presser-lifter cam-lever 39. The head 4 also carries the needle-thread tension-device 40.

The needle-thread it runs from the supply to the stationary guide-hook 4| on the outside of the solenoid casing; thence to and through the tension-device 4|]; thence under the usual presser-bar controlled guide-bar 42; thence upwardly to and around the stationary threadguide 43; then down to and around the stationary thread-guide 44; thence through the take-up eye 29; thence downwardly through the thread-guide tube 45, which is carried by the needle-bar, to the eye of the needle. Journaled in bearing lugs below the bed is the rotary main-shaft 46 carrying the beltpulley 41 which is wrapped by the belt 48 running around the pulley 49 of the conventional sewing machine driving motor 58 fixed externally of and to the bracket-arm standard 2.

Cooperating with the needle 6 in'the formation of stitches is the oscillatory loop-taker 5| having the loop-taking hook 52 which seizes thread-loops from the needle and 'casts them about the lower stationary bobbin-thread case 53. The loop-taker 5| is carried by a shaft 54 to which is fixed a crank-arm 55 connected by a link 58 to one arm 51 of a lever the other arm 58 of which is connected by the link 59 to another lever 68 which is vibrated by the grooved cam-cylinder 8|. The present loop-taker 5|, bobbin-case 53 and driving parts 55, 56, 51 and 58 are constructed substantially in accordance with the disclosure of U. S. Patent No. 663,696; Diehl and Grieb; Dec. 11, 1900.

The feeding mechanism comprises the feed-dog 62 carried by the feed-bar .63 mounted at its rearward end on the pintles 64 of the feed-rocker which is mounted on frame pintles 66, Fig. 1,

and has rigid with it a forked-arm 61, Fig. 5, cmbracing the feed-cam 68 on the main-shaft 45. The feed-cam 68 is of conventional form and is designed to impart a full feed-stroke to the feedbar in of rotation of the main-shaft. The feed-bar 83 has a downwardly inclined forward extension 69 which carries a laterally projecting pin 18 entering a horizontal slot 1| in an intermediate feed-lift lever 12 which is fulcrumed on the bed frame at 13 and carries a lateral roller stud 14 which enters the feed-lift cam-groove 15 in the hub of the hook-oscillating lever 51.

Mounted under the bed of the machine is a block 16 of insulating material carrying three fixed or stationary electrical contacts 11' and three movable contacts 18 which are carried by the respective spring arms 19 mounted on the insulating base 16 and each carrying a followerbutton 80 which is engaged by a respective track 8| of a cam-cylinder 82 of insulating material. Engagement of any of the elevated portions of the tracks 8| of the cam-cylinder 82 with its respective track-follower button 88, closes the respective switch-contacts ll, 18 and energizes the particular coil of the solenoid s connected in circuit therewith. The circuit is shown diagrammatically in Fig. 10, wherein it will be observed that each of the three solenoid coils is connected in series with a respective one of the three switches to a source of direct current. The three tracks of the cam-cylinder 82 operate the switches in properly timed relation to coordinate the movements of the needle to the movements of the loop-taker.

The function of the thread-guide tube 45 is to prevent slack needle-thread, given up by the take-up early in the downstroke of the needlebar, from hitching or looping around the point of the needle 8 before such point enters the work. This guide-tube 45 is inclined toward and terminates at its lower end below the usual needle-clamp 83 which grips the shank of the needle 6.

Operation Starting at 0 position of the main-shaft 46 and cam-cylinder 82, Fig. 9, with the needle up. as in Fig. 1, and the switch in circuit with coil l3 closed, the oscillatory hook 52 of the loop-taker 5| is executing its return stroke and the feed-dog Q has executed a little less than half of its workfeeding stroke. This will be apparent from Fig. 9, wherein the dotted line FB shows when the workfeeding stroke of the feed-dog begins and the line FE shows when the feed-stroke ends. The entire feed-stroke is executed in 90 of motion of the main-shaft.

After the feed-stroke has ended, the needle begins its step-by-step descent at about the 80 position of the cam-cylinder 82 and finishes its descent at about the position, just after the loop-taker hook 52 has been retracted to loopseizing position. As the needle-bar recoils slightly from the lower resilient cushioning washer 26, a loop of needle-thread is caused to bow outwardly from the needle and this loop is immediately seized by the hook 52 and expanded as the hook- 52 advances to cast-off position, Fig. 4, which is the extreme position to which the hook 52 advances after it has seized the needle-loop. The slack thread given up by the take-up 28 on the downstroke of the needle 6 is available at this time and is drawn into the needle-loop as the latter is drawn out or expanded by the hook 52.

When the hook 52 is dwelling in cast-oil position, Fig. 4, preparatory to the execution of its reverse or return motion to loop-seizing position, the bobbin-case 53, which rests upon the hookring, is relieved-of the drag produced by movement of the hook-ring and hence is not pressing forceably against the side of the usual rotationrestraining position-bracket 53' provided for the bobbin-case, as disclosed in U. S. Patent No. 1,388,114; G. Jackson; Aug. 16, 1921. At this time the needle is caused to execute, preferably,

of its entire upstroke in one step, by the simultaneous energization of coils l3 and and deenergization of the lowermost coil l5. This initial long step of the upstroke of the needle-bar elevates the takeup 28 and draws the cast needlethread loop clear of the bobbin-thread case 53 but not up to the work. At about the 310 position,

the needle-bar 'is caused to execute the final short step of its upstroke, by de-energization of coil l4,

and the take-up completes the drawing up of the needle-loop at a comparatively slow speed and sets the stitch.

The initial long step followed by the final short step of the upstroke of the needle-bar and takeup avoids the snarling and kinking of the needleloop which results when an attempt is made to draw the needle-loop all the way up to the work.

at an accelerating speed, as in the machines of the prior art having solenoid-operated needlebars and take-ups. Also, excessive hammering or overthrow blows against the cushioning washers are avoided and massive solenoid 'armatures are not required. Furthermore I am, by the multiple-step-stroke solenoid-operation of the needle-bar and take-up or other reciprocatory part of a sewing machine, enabled to spread the times required for the execution of the strokes of the needle-bar, take-up, or other part, over appreciable time-portions of a complete stitch-forming cycle of operations of the machine as -a whole, affording periods of slow motion intermediate extreme positions of the needle-bar, take-up, or other part, to better harmonize the operation thereof with the operation of other mechanisms of the machine.

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

1. A sewing machine having a reciprocatory needle element, a complemental loop-taker element, and a work-feeder element, a multiplestep-stroke operating solenoid for one of said elements, and means to actuate the remainder of said elements in timed relation to said solenoidoperated element.

2. An electromagnet sewing machine having, incombination, an endwise reciprocatory needle de-,

vice a complemental loop-taker device and a work-feeder device, a main-shaft, a solenoid having three or more energizing coils controlled by timing switches operated by the main-shaft to impart step-by-step movements to one of said -devices in each of two opposite directions, and

means to actuate the remainder of said devices in timed relation to said one of said devices.

3. An electromagnetic sewing machine having, in combination, an endwise reciprocatory needle 5 device a complemental loop-take device and a work-feeder device, a main-shaft, a solenoid having three or more energizing coils controlled by timing switches operated by the main-shaft to impart step-by-step movements to' said needle- 10 device in both its downstrokes and upstrokes, and means to actuate said loop-taker and work feeded devices in timed relation to said needle device.

4. An electromagnetic sewing machine having a solenoid-operated needle-bar, a needle-clamp carried thereby, a needle having a shank gripped by said needle-clamp and a reduced blade, a needlebar-operatedtake-up, a loop-taker complemental to said needle, 9. bobbin, and a needle-threadv guide-tube carried by said needle-bar and inclined toward the blade of said needle, said guide-tube needle-bar and disposed in its entirety in the upper portion of said head, and a spring-pressed presser-bar disposed in said head entirely below said solenoid.

6. An electromagnetic sewing machine having a frame formed with a bed and an overhanging bracket-arm terminating at its free end in a head, a needle-bar journaled to slide vertically in said head, a multiple-coil solenoid surrounding said needle-bar and disposed in its entirety in the upper portion of said head, a spring-pressed presser-bar disposed in saidhead entirely below said solenoid, and means in said head to. adjust the pressure of the presser-bar spring.

7,. A sewing machine having, a needle, a needlebar, a needle-bar-operated thread take-up, a mmti'ple-step-stroke solenoid for .operating said needle-bar, a loop-taker complemental to said needle in the formation of stitches, and means to control the operation of said solenoid to cause the needle-bar to pause between the limits of its upstroke.

8. A sewing machine having a needle, aneedlebar, a multiple-st'ep-stroke needle-bar-operating solenoid surrounding said needle-bar, a looptaker complemental to said needle in the forma- 55 tion of stitches, means to control the operation of said solenoid to cause the needle-bar to pause between the steps of its upstroke, and a needlethread take-up actuated by said needle-bar and disposed below said solenoid.

FREDERICK DIEHL,

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