US2218556A - Lockstitch sewing machine - Google Patents

Description

Och-22 1940. c. F. RUBEI. 2,218,556

` LOCKSTITCH SEWING MACHINE Filed Aug. 18, 1937 4 sheets-sheet 1 Us i, 10 Flea 1 7 9 j 5 .9 15( Jg' 12 I g l f 5l -ZL P9 j 17 a 62 q 1151 Zi-. z

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Oct. 22, 1940. C. F, RUBEL 2,218,556

LOCKSTITCH SEWING MACHINE Filed Aug. 18, 1957 4 Sheets-Sheet 2 y@ w75 er Y WITNESSILS- 55 INVENTOR- 6. NL. ,52 charm :v1/mimi,

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Oct. 22, 1940. c. F. RUBEL 2,218,556

LOCKS TITCH SEWING MACHINE Filed Aug. 1B, 1937 4 Sheets-Sheet 3 I N VEN TOR:

E Charlas Rubl/ y 4 BY @t Q A T'I'ORNE YS.

OL 22, 1940. C, F, RUBEL 2,218,556

LOCKSTITCH SEWING MACHINE Filed Aug 18. i937 4 Sheets-Sheet 4 W1 TNESSES-- ,55 INVENTOR;

(fg 5f j I Charles fuiml,

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Patented Oct. 22, 1940 g Locxs'rrrcn SEWING-MACHINE Charles F. Rubel, Chicago, Ill., assigner to Union j Special Machine Company, Chicago, Ill., a. corporation of Illinois Application `August 1s, 1937, serial No. 159,645

7 Claims.

This invention relates to sewing machines of the type wherein a complemental rotary stitchforming means cooperates with the needle in the l .production of lwhat are known as lockstitch seams. Such complemental stitch forming means usually consists of an axially hollow hook component, a non-rotating frontally open hollow bobbin case holder which occupies the hollow of the hook component, 'and a removable bobbin 10 case with a needle clearing opening at its top which in turn occupies the hollow of the holder and accommodates a bobbin within it.. In descending, the needle passes in closeproximity to thefront of the rotary hook member, and in the eventthat it is bent or deflected bYma cross seam or other thickness irregularity in `the material being sewed, itv invariably enters the open front of the bobbin case holder through the needle clearing opening in the top of the bobbin case and fouls the bobbin within said case, thereby either scoring or otherwise damaging the bobbin to the extent of rendering it unsuitable for further use, or being itself broken by impact with 35 A further aim of my invention is to attain the foregoing advantages without interfering with the normal functioning of either the complemental stitch-forming means or the needle, which desideratum I also attain as hereinafter set forth 40 through formation of the guard as a forward cam projection, of the rotary hook member which during rotations of the latter passes transversely of the path ofthe needle as the latter descends without contacting it except in the event of the 45 contingencies noted.

Other objects and attendant advantages will appear `from the following detailed description of the attached drawings, wherein Fig. I is a fragmentary view, in plan, of a lockstitch sewing machine conveniently embodying my invention, a portion of its work support having been cut away forv exposure of important underlying elements of the machine mechanism.

55 Fig. II is a' staggered cross-sectional view of the machine taken as indicated by the arrows II-II in Fig. I.

Fig. III is a fragmentary sectional view axially through the complemental stitch-forming means which cooperates with the needle in producing 5 the lockstitch seams, the section being taken as indicatedby the arrows III-III in Figs. I and II and drawn to a largerscale.

Fig. IV is a detail sectional view taken as indicated by the arrows IV-IV in Fig. III. 1o

Figs. V and VI' are views corresponding respectively to Figs. III and IV, but with the rotary hook element of the complcmental stitch-forming means and the needle in a diierent position.

Figs. VII and VIII are, in turn, views like Figs. l5 V and VI` with the rotary hook element o f the complemental stitch-forming means and the needle in still another position; and

.Y Fig. IX is a perspective view of a gib associated with the rotating member` of the complemental 20 stitch-forming means which constitutes the needle guarding means of my present invention.

The lockstitch sewing machine herein illustrated is identical in construction with that of my copending application Serial Number 159,646, concurrently filed herewith, its horizontal work support ,I having a removable throat plate 2 with an opening 3 ltherein through which a feed dog 4 operates upwardly to intermittently advance the material (not shown) being sewed on said work support. A presser foot 5 pivotally connected at 6 to a shank 1 at the bottom of a presser bar 8, serves, as ordinarily, to hold the material down on the work support. 'I'he needle 9 of the machine is carried at the lower end of a vertically reciprocating bar I0 above the work support I which is actuated by suitable mechanism (not shown) so that said needle is moved up and down through the throat plate 2 to Vcooperate with a complementalA rotary stitch-forming 40 means generally designated by the numeral II.

The feed dog 4 of the machine is mounted on the top of a cantilever I2 which overreaches the complemental stitch-formingv means II` and which has a vertically-slotted pendant shank I3 secured by a clamping screw I4 to the front end of a feed bar I5. By virtue of this construction, the feed dog 4 can be adjusted vertically relative to the feed bar I5 in adapting the machine for operation on materials of different thicknesses. At its rear end the feed bar I5 has a pivotal connection I6 with a rocker I1 on a, rock shaft I8 whereof the opposite ends are engaged kin downwardly-projecting bearing lugsy I9, 20 of the work support I. Up and down or lift movements are or feed movements from the shaft 2| through means including an eccentric 21 on said shaft with a strap 28 whereof the rod 29 is composed of two telescopically interengaging components 29a, 29h, the component 29h being pivotally connected at 38 to the rocker I1 as shown in Fig. II. By means of a lazy bar 3I pivotally connected at 32 to the component 28h of the strap rod 23, said component is coupled with an arm 33 on a longitudinally-extending regulating shaft 36 also suitably ;lournaled beneath the work support I. By rotatively adjusting the regulating shaft 35, it is possible to vary the throw of the feed dog 4, and in turn the stitch length as may be desired or required.

The complemental Stich-forming means I I comprises a rotary hook mem'ber 36 with a needle loop-engaging beak 31 and a loop-releasing tail 38; a bobbin case holder 39 which fits into the hollow of the Irotary hook; and a case 40 for a bobbin 4I which in turn fits into the hollow of the bobbin case holder and which is provided with a needle clearing opening 42 at the top. As usual, the rotary hook member 36 is formed at the back with an axial boss 43 and secured by means of screws 44 to the front end of a shaft 45 which is parallel with the shaft 2| and journaled in a bearing 46 intergrally formed with the bearing 22. By a suitable transmission mechanism (not illustrated), the rotary hook member 36 is rotated twice during each feeding traverse of the feed dog 4 and each vertical reciprocation of the needle 9. Moreover, as usual, the face flange 41 of the bobbin case holder 39 is formed at the top with a notch 48.for engagement by a rearward projection 49 on a rotation-restraining nger 50 secured by screws I to the underface of the work support I. As shown in Fig. I, sufficient clearance is allowed between the projection 49 of the rotation-restraining finger 50 and the notch 48 of the flange 41 on the bobbin case holder 39 to permit free reeving of the needle thread (not illustrated) during the formation of the lockstitches in the well known way. As in my copending application, and as shown in Figs. III and VI, the circumferential rib 52 on the bobbin case holder 39 is considerably narrower than the internal receiving groove 53 of the rotary hook member '36 so that normally said bobbin case holder is free to oat axially. At 54 is indicated a steadying element in the form of a triarm whereof the cylindric shank 55 is secured by means of a set screw 56 in a boss 51 at the end of an arm 58 pivoted for horizontal movement to the screw stud 59 surrounded by a helical spring 60 engaging upwardly into the feed bar I5. 'Ihe arm 58 is held in the position shown in Fig. I by a latch hook 6I, pivotally connected at 62, to one side of the pendant projection 26 of the feed bar and urged upwardly by a spring 63.

By depressing the latch 6I, the arm 58 and the steadying element 54 carried thereby will be swung outward away from the rotary hook member 36 as far as permitted by a stop 64 on the feed bar I6 by the helical spring 60, so that access may be had to the bobbin case holder 39 when interchange of bobbins is necessary. The operation and function of the steadying .member 64 is fully described in the copending application hereinbeiore referred to and need not therefore be further dealt with herein.

The guard which I have provided to prevent the needle 9 from fouling the bobbin 4I of the complemental stitch-forming means II in the event that it is deflected or bent by cross seams or other thickness irregularities in the material being sewed in the machinel is in the form of a forwardly projecting edge cam 66 on a segmental plate gib 61 lying radially beyond the loop engaging beak 31. said gib providing the loop-releasing tail 38 and being detachably secured to the periphery ofthe rotary hook member 36 by three screws 68, see Figs. I and IX. As shown, the cam projection 66 has a straight fiat surface 69 centrally between oppositely inclined flanking approaches and 1I.

The operation of my improved sewing machine is as follows: During each rotation of the hook member 36, the approach 10 of the guard cam projection 66 reaches the path of the needle 9 at just about the time when said needle has `descended to the level oi' the top of said hook member as shown in Figs. III and IV. With continued rotation of the hook member 36 and further'descent of the needle 9, the straight porl tion 69 of the guard cam 66 crosses the path of the needle slightly to the rear of the latter as shown in Figs. V and VI so that it does not normally contact with the needle. However, should the needle be bent or deflected inwardly toward the hook member 36 during this portion of the rotative cycle of the latter, it will be urged outwardly gradually by the inclined approach 10 of the cam projection 66 before it approaches the range of the loop engaging beak 31. The needle is Aaccordingly prevented from entering the open front of the bobbin case holder 39 through the needle clearing opening 42 in the bobbin case 40, and from fouling the bobbin 4I as it continues in its descent to its lowest position (Figs. VII and VIII) by which time the flat portion 69 of the cam has passed from behind it. It is to be particularly noted from'Figs. V and VI, that the portion 69 of theguard passes behind the needle 9 at a time when the bobbin case holder 39 is free to float axially.

It will thus be apparent from the foregoing, that I have provided a simple and efficient means for preventing injury to the complemental stitchforming mechanism of a lockstitch sewing machine by a bent or deflected needle as well as for protecting the needle against breakage. While I have illustrated and described my invention for convenience in association with a special and improved form of complemental rotary lockstitchforming means, it will be evident that the same can be embodied with attainment of advantages equal in all respects to those hereinbefore pointed out, in complemental lockstitch-forming means of ordinary construction without departing from the scope of my invention as defined in the appended claims. Y

Having thus described my invention, I claim:

1. In a lockstitch sewing machine, reciprocating needle; cooperative complemental stitchforming means with its axis at right angles to the needle including an axially-hollow rotary hook member with a needle loop engaging beak, a frontally-open non-rotating bobbin case holder within the hollow of the rotary hook member, a

bobbin case with a needle clearing opening in its top removable from said holder, and a bobbin within the bobbin case; and a guard movable with the complemental stitch-forming means for engaging the needle, in the event that the latter is bent or deflected, before it reaches the path of the loop seizing beak of the rotary hook member and preventing said needle from fouling the bobbin within the bobbin case.

2. In a lockstitch sewing machine, vertically reciprocating needle; cooperative complemental stitch-forming means including a horizontallyarranged hollow rotary hook component with a needle loop engaging beak; a frontally open nonrotating bobbin case holder within the hollow of the rotary hook component, a removable bobbin case tting within said bobbin case holder and having a needle clearing opening in its t?, and a bobbin within said bobbin-case; and 'a needle guard in the form oi' a forwardly projecting cam edge at the periphery of the rotary hook for engaging the needle, in the event that it is bent or deflected as it descends, before it moves into the path of the needle loop engaging hook to prevent it from fouling the bobbin within the bobbin case.

3. In a lockstitch sewing machine, a vertically reciprocating needle; cooperative complementa] stitch-forming means including `a horizontallyarranged axially hollow rotary hook member with a needle loop engaging beak, a frontally open nonrotating bobbin case holder within the hollow of the rotary hook member, a bobbin case fitting within said -bobbin case holder and having a needle clearing opening in its top, and a bobbin within said bobbin case; and a needle guard in the formo! a forwardly projecting cam edge at the periphery of the rotary hook which passes behind the needle during descent of the latter without contacting it normally, but which, in the event that the needle is bent or deflected, engages it before, it moves into the path ef the loop seizing beak of the rotary hook member to prevent it from fouling the bobbin within the bobbin case holder.

4. In a lockstitch sewing machine, a vertically reciprocating needle; cooperative complemental stitch-forming means including a horizontallyarranged axially-hollow rotary hook component with a needle loop engaging beak and with an attached segmental gib providing a needle loop releasing tail, a frontally open non-rotating bobbin case holder within the hollow of the rotary hook component, a bobbin case fitting within said holder and having a needle clearing opening in its top, and a bobbin within said bobbin case; and a needle guard in the form of a forward edge cam projection on the gib aforesaid which passes behind the needle during descent of the latter without contacting it normally, but which, in the event that the needle is bent or deflected, engages it before it moves into the path of the needle loop engaging beak to prevent it from fouling the bobbin within the bobbin case holder.

5. In a lockstitch sewing machine, a reciprocating needle; cooperative complemental stitchforming means including an axially-hollow rotary hook member with an internal circumferential groove, a frontally open non-rotating bobbin case holder having a narrower circumferential rib engaged in the groove of the rotary hook so that said bobbin case may normally oat axially, a bobibn case tting within said holder and having a needle clearing opening in its top, and a bobbin within said bobbin case; a steadying member adapted to coact with the bobbin case in urging the bobbin case holder inward of the rotary hook member to prevent pinching of the needle thread between the rear face of the rib and the corresponding face of the groove 'during each stitch-forming cycle; and a needle guard in the form of a forward cam projection at the periphery of the rotary hook component which passes behind the needle during descent of the 30 latter without contacting it normally, but which, in the event that the needle is bent or deflected. engages it to prevent it from fouling the bobbin within the bobbin case at times when the bobbin case holder is free to oat axially as aforesaid.

6. In a lockstitch sewing machine, a recipro cating needle; cooperative complemental stitchforming means having its axis at right angles to the needle and including a rotating component with a. needle thread loop engaging beak; and a needle guard on and movable with said complemental stitch-forming means and arranged to engage the needlel before the latter moves into the path of the loop engaging beak.

'1. In a lockstitch sewing machine, a reciprocating needle; cooperative complemental stitchforming means having its axis at right angles to the needle and including a member with a needle lthread loop engaging beak; and a needle guard on said member radially beyond the beak arranged to engage the needle before the latter moves into the path of said beak.

CHARLES I". RUBEL.

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