US2201384A

US2201384A - Looper mechanism

Info

Publication number: US2201384A
Application number: US202761A
Authority: US
Inventors: Albert H Weis
Original assignee: Willcox and Gibbs Sewing Machine Co
Current assignee: Willcox and Gibbs Sewing Machine Co
Priority date: 1938-04-18
Filing date: 1938-04-18
Publication date: 1940-05-21
Anticipated expiration: 1957-05-21

Description

May 21, 1940. A. H. WElS LOOPER MECHANISM Filed April 18, 1938 s Sheets-Sheet 1 INVENTOR ALBE/ZTliVE/S A TTORNEY' Y 1940- A. H. was

LOOPER MECHANISM 3 Sheets-Sheet 2 Filed April 18, 1938 May 21, 1940.

A. H. WElS 2,201,384

LOOPER MECHANISM Filed April 18. 1938 s Sheets-Sheet 3 85 WW8 J 54 v c ATTORNEY 4 Patented May 21,

' UNITED. STATES Loorsn Mechanism Albert R. Weis, Nyack, N. 1., anignor to Wilicox & Gibbs Sewing Machine Company, New York, N. Y., a corporation of New York ApplicationiApril 18, 1938, Serial No. 202361 11 Claims.

' The present invention relates to improvements in sewing machines of the type employing a thread-carrying looper and more particularly to a new actuating and control mechanism for a looper, and also to a new mechanism for control! ling the looper thread.

In the construction and operation of sewing 7 machines which are particularly used for sewing heavy and thick materials and which there- 10 fore require a high needle lift, great disadvantage has been experienced when the feeding and advancing of the work takes place while the needles are still in the work, as excessive needle breakage occurs. Various efforts have been made to reduce such breakage by using needles having a relatively short blade, but then it was often found that when the needle entered the material sufficiently to afford proper cooperation of the needle thread with the looper, feeding took place prematurely and the shanks of the needles also entered into the material "thus spoiling the appearanc of the seam and the work and often rendered the latter unfit for use or sale.

It is the principal object of this invention to overcome these disadvantages of known sewing machines and to obtain a relatively short needle movement so that the shanks of the needles do not enter'the material.

Another important object of the invention is to provide a new and improved looper operating mechanism for a sewing machine of the type described above which imparts a new and improved movement to the looper.

It is still another object of the invention to 7 provide such a new looper drive whereby the dwell in the advanced position of the looper is very much longer than the dwell in the retracted position thereof,

A feature flowing from the attainment of this 40 object is that the needle need not be projected or protruded below the throat plate to the same substantial length as in loopeiimechanism heretofore proposed. v

More specifically, it is an object of the invention to design a mechanism which: moves the looper into the needle loops which have been thrown out by the needles after they. have pierced through the work piece, then substantially disrupts the forward and rearward movement of the looper and moves the latter laterally while the needle rises and begins its descent; and moves the looper quickly backward just before the nee- A die point could come in contact with the top of the looper. Features of theinvention to attain these ob- 'jects are a particular arrangement of driving mechanism consisting of a drive shaft, a plurality of eccentrics on such shaft connected to a system of levers which, in turn, are connected to alooper shaft for imparting to the latter recip- '5 rocatory movement inaxial direction and oscillatory movement in lateral directions.

, another, and very important feature of the invention consists in the particular dimensioning of the various elements'and in their particular 10 positioning-relative to each other so that the new looper movementwith a smooth action and a pronounced dwell can be obtained. A still further object is the provision of a new and improved loop spreading device and simple 15 mechanism for actuating the same.

A feature for obtaining the last-mentioned obiect consists of a single pivoting lever which is directly connected to the looper shaft and the loop spreader so that the latter is actuated simul- 2'0 taneously with and moved in opposite directions to the movement of the looper shaft.

Other objects, features and advantages of the present invention reside in the simplicity of the entire mechanism its low cost of production and 25 operation, in the fact that a very high lift of the needle above the work plate is obtained, in the successful use of a needle or needles with very short blades without the danger of the needle shanks entering the work at, any, portion that is 30 being stitched; in the elimination or very low breakage of the needles; .and in the fact that the stitches in heavy materials or across other seams are pulled up, tightly and skip stitches are avoided. These and-other objects. features and 35 advantages will appear more in detail from the following description and the accompanying drawings, in which: l

Figure 11s a front view, partially in section, oif

the looper actuati g and loop spreading inecha- 40 nism according t the invention.

Fig.2 is a plan view.

Fig. 3 is a section along line 3-4 of Fig. 2.

Fig. 4 is a section. along line 4-4 of Fig. 2.

Fig, 5 is 'a diagrammatic showing of the move- 45 ment of the looper and its driving mechanism.

Fig. 6 is a bottom view of the throat plate and. the loop spreader.

- Before describing the present improvements and mode of operation thereof in detail it should so be understood that the invention is not limited to the details of construction and arrangement of parts shown in the accompanying drawings, which are merely illustrative of the present pre-'- ferred embodiments, since the invention is ca- 55 pable of other embodiments, and the phraseology employed is for the purpose of description and not of limitation.

Referring more in detail to the drawings, I8 indicates asupporting bed of a sewing machine having the usual standard II and overhanging arm (not shown), supporting a main drive shaft which reciprocates a needle bar I2 having one or more needles I3 secured to its lower end, relative to the bed ID. A throat plate I4 is secured within a cutout portion of the work plate 55 which, in

turn, is secured to parts of the supporting bed I0. As shown, particularly in Fig. 6, the throat plate I5 is provided with slots I6 for accommodating a feed dog (not shown) and slots I! through which needles I3 pass in their reciprocatory movement. A groove I8 in the lower surface of the throat plate I4 accommodates a bar I9 having a short arm 29 at one end and a pair of loop spreaders 2| projecting forwardly, that is in the direction of feed. Each of the loop Spreaders 2| consists of a hook 22 having an undercut 23 at one side thereof for guiding the thread of the looper loop. Guide bars. 24 which are sunk into corresponding grooves 25 in the throat plate I4 and secured thereto by screws 26, have grooves 21 in which bar I9 is slidably supported for reciprocatory movement in longitudinal direction, and so adjusted that the points 22 of the loop spreader hooks 2| slightly overlap the front edge of the needle slots II.

A driving shaft 28 is rotatably guided in

bearings

29 and 38 forming parts of the supporting bed In and preferably driven by the main shaft in the overhanging arm through any suitable driving connection. As shown, particularly in Fig. 2, an eccentric 3| is fixed to shaft 28by means of a sleeve 32 which is integral with the eccentric 3|, and enclosed by a split bearing 33 at one end of a connecting rod '34. A set screw 35 on sleeve 32 serves to adjust theeccentric 3| relative to shaft 28.

A support 36 is secured to the bed I0 and has bearings 31 thereon in which a shaft 38 is retatably guided. ,A bell crank lever 39 consisting of rocker arms 40 and 4| is secured to' shaft 38 so as to oscillate with said shaft relative to the support 36. Rocker'arm 48 of bell-crank lever 39 is positioned intermediate bearings 31 and fixed to shaft 38 by screws 42. The free or rocking end of rocker arm 40 comprises two fingers 43 between which the other end 44 of the eonnecting rod 34 is pivotally secured by means of a pivot pin 45. The second rocker arm 4| of bell crank lever 39 is rigidly secured to the free end 46 of shaft 38 by means of a screw 41 and disposed at an obtuse angle relative to rocker arm 49 as shown particularly in Figs. 3 and 4 of the drawings. A pivot pin 48 extending parallel to shaft 38 and pivot pin 45 is rigidly secured to the free or rocking end of rocker arm 4| and has a ball 49 at its outer end. A connecting rod 59 is pivotally secured to pivot pin 48 by means of a bearing 5| enclosing the ball 49, and carries a similar bearing 52 at its other end in which a ball 53 of a pivot pin 54 is housed.

A second eccentric 55 having a rounded outer surface 56 is adjustably fixed to shaft 28 closely adjacent the other eccentric 3| by means of a sleeve 51 which is integral with the eccentric 55 and a set screw 58 on the sleeve 51, and is enclosed by a split bearing 59 forming one end of a connecting rod 68 which carries at its other end a bearing 6| in which a ball-shaped end 62 tral part 64 of connecting rod 59 which connects bearings 59 and 6|, is adjustable in its operative length by being provided with leftand righthanded screw threads, respectively, at the outer ends 55 which screw into the bearings and are secured in fixed position relative to the bearings by tightening nuts 66. i

A bell crank lever 67 having arms 58 and 59 is capable of pivoting about a 'verticalshaft secured within an aperture in bed I0 and an aperture II in an overhanging standard 12 which forms part of bed I9. Pivot pin 63 which hasa fixed collar or flange, '13 passes through an aperture M at the outer end of arm-68 of the bell crank lever and is rigidly secured thereto by a nut 15. The other arm 69 of the bell crank lever has a bore I6 in which a shaft TI is secured by a screw 18. An angular lever 19 which forms an essential feature of the present invention, includes an arm which has an axial bore 8| in the end which forms the vertex of the lever 79, and a split socket 82 at the other end. Socket 82 encloses a ball 83 which is freely movable on shaft H of the bell crank lever 51. The other arm 84 of lever I9 carries rigidly secured to its outer end the pivot pin 54 which is connected by already described.

A looper shaft 85 is slidably and rotatably supported in bearings 86 and 81 formed in uprights 88 integral with the'bed II). A needle guard 99 is pivotally secured at one end to one of the uprights 83 by a screw 99' and carries at its other end a locking device 90 for looking it to the other upright to bridge the two uprights. Looper shaft 85 is positioned with one end within bore 8| in arm 80 of the angular lever 19 and fixed thereto by a set screw 9|, so that bymovement of the arm 69 about the shaft "I0, looper shaft 35 is moved either to the left or right of Figs. 1 and 2. A pair of thread carrying loopers 92 are secured to looper carriers 93 which, in turn, are screwed to looper shaft 85. A collar 94 having a peripheral groove 95 therein is likewise screwed to looper shaft 85. A lever 96 is pivoted about a screw 91 in upright 83 and has a slot 99 in its upper end. in which the short arm 28 of the loop spreader bar I 9 engages. Slot 99 is made of such shape so as to permit lever '96 to pivot relative to arm 20 and to reciprocate spreader bar I9 in lateral directions without play betweenarm 28 and lever 96. The lower end of lever 96 carries'a stud I90 which fits into groove 95 of collar 94. Accordingly, a movement of shaft 85 in one direction automatically produces a. movement of the loop spreadersin the opposite direction.

In theoperation of the device, and considering only one needle and one looper as the operation of both'needles and of both loopers are identical, when the needle with its thread is in down position below the work plate, the looper is in retracted position, as shown particularly in Fig. 4.

-wardly and enters the material on the throat plate I4, it passes through the needle guard plate only a short distance and then begins to retract. During this retracting movement of the needle, cam 3| through connecting rod 34,

bell crank lever 39, connecting rod 58 and angu- 75 .the loop spreader 2|.

lar lever 19, which pivots about ball 83, rotates looper shaft 85 and advances the looper quickly between the needle and its thread. 'I'hereupon, the needle is retracted completely so that the loop is formed in the needle thread about looper 92. During this latter part of the upward movement of the needle and during its initial downward movement, the material is advanced, while the looper remains in its advanced position and is shifted laterally to the right by movement of cam 55 through connecting rod 60, bell crank lever 61, lever 19 and looper shaft 85, so that the looper with the needle loop thereon moves toward the right of the needle. Simultaneously with the lateral movement of the looper toward the right, spreader bar I9 is moved to the left through pivotal movement of lever '96, engages the looper thread and forms a loop therein.

When the needle in its downward movement again has passed through the material on the throat plate to make the next stitch, it enters into the loop in the looper thread formed by moved into the loop, and not until such time, the looper is retracted very quickly, moved laterally to the left by cam 55 and the respective connecting elements 60,51 and 19 so as to return to its original position at the left side of the needle. Simultaneously with the lateral movement of the looper, the spreader bar 2| is moved to the right by lever 96 and disengages from the looper loop.

Thereupon, the same operation is repeated: while the needle begins its upward movement, the looper moves quickly between the needle and its thread so as to form a loop about the looper, the material advances, the looper moves laterally to the right of the needle, and the loop spreader moves to the left and forms a loop,

in the looper thread, the needle comes downwardly and passes through the loop formed by the looper thread, the looper retracts quickly and moves to the left and the loop spreader disengages from the loop in the looper thread.

In Fig. of the drawings, the movement of the various levers for advancing and retracting the looper has been indicated diagrammatically. The circle C indicates the path described by the cam 3|; l is the starting or retracted position; 2 the maximum advancedposition of the looper 92 at the forward movement of cam 3|, connecting rod 94 and arm 40 of bell crank lever 39, when the other arm ll and connecting rod 50 are in a straight line; 3 the maximum forward movement of cam 3|, connecting rod 34 and arm 40; and I the maximum advanced position of the looper 92 at the return movement of cam 3|,connecting rod 34 and arm 40. It

will be readily noticed from Fig. 5 that the maximum advanced positions 2 and 4 of looper 92 are identical and that the intermediate position 3 is located slightly in back of these maximum positions. Therefore, the looper advances quickly. from position I to position 2 'where it maybe said to remain substantially stationary while the needle is retracted, the material advanced, the looper moved laterally to the right (see Fig. 1), the loop spreader moves to theleft and forms the loop in the looper thread and the needle comes down and passes through the material and into the looper thread loop. Not until after all these steps have been completed does the looper move backward quickly from position .4 to position I'. V

.The present invention makes it possible to stitch forming mechanism including a rod After the needle has transmit to the looper shaft both the loop taking and needle avoiding movements by a single element, that is, the angular lever 19. Upon tilting of the bell crank lever I9, for effecting the needle avoiding movement and the actuation I of loop spreader bar l9, bearing?" on lever 19 pivots on ball 83 which, in turn, slides on shaft 'II in outward-direction,

Variations and modifications may be made .within the scope of this invention and portions of the improvements may be used without others.

Having thus described the invention, what is claimed as new is:

-l. In a sewing machine, the combination of a stitch forming mechanism; a looper in said ll mechanism; a. loop spreader; means for mounting said spreader for sliding movement; a rod for supporting said looper; and only one lever directly connecting said loop spreader to said rod for moving said loop spreader. 1

2. In a sewing machine, the combination of a ov- 1 able longitudinally lengthwise of said mac e;

a looper on said rod; a loop spreader; and a single lever for directly connecting said rod with 86 said loop spreader for moving the same in the opposite direction to the movement of said rod.

3. In a sewing machine, the combination of a work plate; a needle having retracted and advanced positions above and below the work plate, respectively; a rod; a looper on said rod; a loop spreader; a single lever connecting said rod with said loop spreader; and means for moving said rod in one direction for advancing said looper relative to the needle and for moving the loop 95 spreader in the opposite direction.

4. In a sewing machine, the combination of a work plate; a needle having retracted and advanced positions above and below the work plate, respectively; a rod; a looper on said rod having advanced and retracted positions relative to the needle; a driving shaft; means for rotating said shaft; at least one lever connecting said shaft with said rod for moving said rod and said looper into advanced and retracted positions relative to the needle and for imparting a dwell in the movement of said looper in both advanced and retracted positions, the dwell in the advanced position of said looper being longer than the dwell in the retracted position thereof; at least one l0 second lever connecting said driving shaft with said rod for moving said rod and said looper in an angular direction relative to the first .movement thereof; a loop spreader; and a single lever connecting said rod with said loop spreader for II moving the same in the oppositedirection relative to the second movement of said rod.

5. In a sewing machine, the combination of a looper shaft; 9. looper on said shaft; an actuating lever secured ,at one end to said shaft; a bell Q crank lever having at least one arm; a connecting rod pivotally connected at opposite ends to said arm and the other end of said actuating lever; and means for pivoting saidbell crank lever to move said arm into advanced and retracted posill tions relative to said looper shaft; said bell crank lever being so positioned relative to said looper shaft that said arm and said connecting rod are in a substantially straight line when said arm is in the advanced position.

6. In a sewing machine, the combination of a work plate; a needle having retracted and advanced positions above and below the work plate;

a looper having retracted and advanced positions relative to the needle; a lever;- a connecting rod 1' pivotally connected at opposite ends to said lever and saidv looper; and means for pivoting said lever to move said looper into the advanced and retracted positions, said lever and looper being so positioned relative to each other that said looper is held in the advanced position for a considerably longer time than in the retracted position and said lever and connecting rod are ina substantially straight line when said looper is in the advanced position.

7. In a sewing machine, the combination of a bell crank lever having a first and a second arm; a connecting rod pivotally secured at one end to said first arm; a drive shaft; means for rotating said drive shaft; an eccentric. on said drive shaft pivotally connected to the other end of said connecting rod for moving said first arm into advanced and retracted positions relative to said drive shaft; a looper shaft; a looper on said looper shaft; an actuating lever secured at one end to said loopershaft; a second connecting rod 'pivotally secured at opposite ends to the other end of said actuating lever and the second arm of saidbell crank lever; said bell; crank lever being so positioned relative to said eccentric and said looper shaft that said second arm of the bell crank lever and said second connecting rod are substantially in a straight line when said first connecting rod and said first arm of the bell crank lever are in retracted position relative to said drive shaft,

8. In a sewing machine, the combination of a base including a work plate; a needle having retracted and advanced positions above and below the work plate respectively; a rotatable driving shaft; a pair of eccentrics in'said driving shaft; a looper rod extending longitudinally of said driving shaft and mounted for both rotatable and longitudinal movement; a looper carried by and movable with said rod; a lever fixed to said rod;

; means connecting one of said eccentrics to said driving shaft; a looper shaft extending longitudinally of said driving shaft; a looper on said shaft; an actuating lever secured at one end to saidshaft; a bell crank lever having at least one arm; a connecting rod pivotally connected at opposite ends to said arm and the other end of said actuating lever; and means for pivoting said hell crank lever to move said arm into advanced and retracted positions relative to said looper shaft; said bell crank lever being so positioned relative to said looper shaft that said am and said connecting rod are in a substantially straight line when said arm is in the advanced position.

10. In a sewing machine, the combination of a work plate; a needle having retracted and advanced positions above and below the work plate; a rotatable driving shaft; a looper having retracted and advanced positions relative to the needle; a rod for supporting said looper for rocking movement with the rod as an axis of rotation, extending longitudinally -of said driving shaft; an actuating lever connected to said looper for rocking the same; a second lever having at least one arm; means for pivotally mounting said second lever; a connecting rod pivotally connected at opposite ends to said arm and said actuating lever; and means for pivoting said second lever to move said looper into the advanced and retracted positions, said second lever and looper rod being so positioned relative to each other that said looper is held in the advanced position for a considerably longer time than in the retracted position and said am on said second lever and said connecting rod are in a substantially straight line when said looper is in the advanced position.

11. In a sewing machine, the combination of a I bell crank lever having a first and a second arm;

a connecting rod pivotally secured at one end to said first arm; a drive shaft; means for rotating said drive shaft; an eccentric on said drive shaft pivotally connected to the other end of said connecting rod for moving said first arm into advanced and retracted positions relative to said drive shaft; a looper shaft extending longitudinally of said drive shaft; a looper on saidlooper shaft; an actuating lever secured at one end to said looper shaft; a second connecting rod pivotally secured at opposite ends to the other end of said actuating lever and the second arm of said bell crank lever; said bell crank lever being so positioned relative to said eccentric and said looper shaft that said second a'rm of the bell crank lever and said second connecting rod are substantially in a straight line when said first connecting rod and said first arm of the bell crank lever are in retracted position relative to said drive shaft.

ALBERT H.