US2126715A - Blind-stitch attachment for sewing machines - Google Patents

Description

Aug. 16, 1938.

J. F. ARVE R BLIND-STITCH ATTACHMENT FOR SEWING MACHINES Filed Nov. 12, 1936 2 Sheets-Sheet l [JV VENTOR. 5%

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BLIND-STITCH ATTACHMENT FOR SEWING MACHINES Filed Nov. 12, 1936 2 Sheets-Sheet 2 INVEJYJWEI' Patented Aug. 16, 1938 UNITED STATES PATENT, OFFICE BLIND-STITCH ATTACHMENT FOR SEWING MACHINES Joseph 'F. Arver, St. Paul, Minn., ,assignor to Joseph F. Arver and Harold E. Ruttenberg, ccpartners, doing business as Hidstitch Company,

St. Paul, Minn.

Application November 12, 1936, Serial ,No. 110,469

9 Claims.

This invention relates to an attachment for sewing machines and used for the purpose of .designed for high speeds and silent action in chine, this figure showing the device'in operative position :over the cloth plate and adjacent table parts of the sewing machine. Fig. 2 is a front elevation of, Fig. 1 and showing additionally, in

section, certain feed mechanisms below the cloth plate, as on line 2-2 in Fig. 1. Fig. 3 is a left .end elevation of Fig. '2. Fig. 4 is a fragmentary view of the outer end portion of a sewing machine table as on line 4-'--4 in Fig. 2, with the cloth plate removed to reveal certain details of the stitch length'regulating means. Fig. 5 is an under side or bottom view as on line 13-43 in Fig. 2 showing certain plunger actuating means of my device. Fig. 6 is ,a sectional detail view as on lined-6 in'Fig.2. Figs. 7, 8 and 9 are diagrammatic top views of the successive needle actions and stitch "forming steps involved in theuse of my device and Fig. 10 is an enlarged sectional view as :on line Ill-l in Fig. 4 and showing additionally apiece of cloth 2, slightly in perspective, being stitched.

' Referring tothe drawings by reference numerals, :l designates the table or Working surface of a sewing machine and in the outer or left end part of which stitching is done in cloth 2 fed and moved rearwardly in direction of arrow 3 (Figs ,"1 and 3) under the presser foot of the machine. 4 is a removably fixed cloth plate in common plane with table 1| and which in my device is .of special construction and replaces the regular cloth plate of a sewing machine.

(in Figs. 2 and 3) designates the lower, outer extremity of the sewing machine head from wh h p ject downwar y e us P $e.r';foot

bar 6 and needle bar I, both reciprocable vertically as in usual sewing machine structure and. well known in the art, my device utilizing the needle bar reciprocating action to impart horizontal needle reciprocation in a plane parallel tothe table I and over its cloth plate 4. Said needle action provides successive penetrations of the cloth 2 the latter being fed across the cloth plate by the usual feed bar 8 which reciprocates under the cloth plate, being raised during rearward movement for its serrated feed dogs 8D to contact and feed the cloth rearward between cloth penetrating actions of the needle. During forward movement of the feed dogs and bar'they are lowered and the dogs are inactive until again raised for next cloth moving-step. Said feed bar, the feed dogs-and manipulating means therefor are well known in the art but herein described and illustrated for the purpose of disclosing their synchronized action and relation to various parts of my improved device. I

My device involves aspecial presser foot member comprising an L-shaped plate 9 elongated in direction transversely of the direction of the cloth movement, its Vertical arm comprising in part a socket 9A in the bore of which the lower end of the presser foot bar '6 is removably'retained as at '9B. I

The vertical part of said presser foot comprises further avertical wall or plate 9B (see Fig. 2) against the front face of which is slidably engaged a horizontally reciprocable plate Ill by such means as a pair of button-head screws ll or equivalent thereof at the upper edge of plate *IO, other means hereinafter described guiding the lower edge part of plate It) slidably Where the upright and horizontal plate parts of the presser foot member converge. The numeral '9 hereinafter designates the elongated lower plate of the presser foot member.

The needle [2 is removably and adjustably fixed parallel and close to the upper side of plate 9 its point directed toward the left (see Figs. 1 and 12) penetrating the cloth 2 which is humped upwardly in the path of the needle by means of a vertically reciprocable plunger l3 mounted below the cloth plate 4 and projectible upwardly therethrough in timed relation to the needle action, said timed'action of the plunger being accomplished by means of the feed bar action as will presently be described. The upper end of the plunger [3 is formed in its left half as a shoulder ISS and is right half rounded downwardly from the diametrical top edge thus formed, said top edge provided at the middle with a notch I3N traversed by the needle during each cloth penetrating action.

98 (Fig. 2) is a slot in the presser foot plate 9, vertically over the upper end of plunger I3 and so located that the squared shoulder part of the plunger is projected upwardly thereinto and projecting the cloth upward accordingly over and on the said upper end of the plunger and in the path of the needle I2 as the presser foot comes down and the needle comes forward (to the left) and simultaneously penetrates the cloth thus raised in two places, one at each side of the notch of the plunger (see Figs. 2 and 10). The dash line I2 in Fig. 10 designates the path of the needle and most clearly shows the. cloth penetrating action.

Subsequently as the needle is withdrawn, during movement to the right, the presser foot 9 is raised by upward movement of the feed dogs 8D the plunger I3 moves down and the feed dogs move the cloth readwardly one stitch length.

The plunger I3 is retained in a bore of a vertically disposed block I4 secured at I5 to the under side of my special cloth plate 4 said bore being enlarged in lowerpartof the block to permit a compression coil spring I6 about the plunger yieldably pressing the plunger downwardly, the plunger extending out of the lower end of the block and its exposed'lower end continuously and yieldably contacted by a roller I I. Said roller is mounted at the free end of an arm I8 bearing upwardly yieldablyby means of a spring I 88, the other end of said arm pivotally connected at I9 to the lower free end of an inverted L-shaped actuator lever 20 the upper end of which is pivotally secured at 2I to housing I4. At the elbow of said actuator lever is fixed a roller projection 20R, (see Figs. 2, 3 and 5) bearing upwardly and contacting the stem part of a T-shaped cam 22 secured on the under-side of a plate 23 fixed at 24 to the feed bar 8 (see Figs. 2 and 5) and extending in horizontal plane to the left from said bar. This fixed plate 23 is pivotally connected at 25 to a lever 26 comprising an elongated flat metal bar under the cloth plate 4 and pivotally connected to the latter near its outer end on a-pivot 2'! on which it has a limited vertical free action. Said lever 26 extends inwardly, riding freely on top of the feed bar 8 (see Fig. 2) and its inner end carries slidably and pivotally, as at 23P (Fig. 4) an integrally formedcloth feeding dog 8D guidingly retained in slots 48 in the cloth plate 4. The lever 26 and its dog 8D are of course reciprocated by motion of the feed bar 8 through its plate 23 and pivot 25 in thelever 26, said pivots 25 and 231? having slidable mounting, to permit straight reciprocating action of the feed dog 8D and plate 23.

The slight vertical freedom, of parts just described, on pivot 21 is to allow the feed dogs to move up and down with the feed fork.

It will now be understood that the cam action of the T-shaped cam 22 contacting roller 20R while reciprocating over the latter, provides a certain rise and fall of said roller, which move ment'transmitted to lever 20 causes the latter to swing at its lower end and oscillates the roller I! in vertical plane, the roller in turn raising the plunger I3 at correct time for'the cloth penetrating action previously described. Release of said cam contact with roller 20R allows spring I 6 to function and pressing the plunger down out of the path of the needle, this taking place and the plunger remaining retracted as the cloth is moved rearward each step or stitch.

The needle reciprocating means are entirely over or above the cloth plate, being actuated directly by the needle bar, which action is of course synchronized with the cloth feeding means described. I will now describe in detail the needle action means.

The reciprocable upright plate I0 is provided intermediate its ends with a diagonal slot IDS engaged by a suitable horizontal projection 28F of the block 28 removably secured as at 29 to the lower end part of the needle bar I. The length of slot IDS, extent of reciprocation of the needle bar 1, determines the horizontal stroke of plate Ill. The needle is preferably clamped at its heavy end in the horizontal base 308 of an L-shaped bracket 30 the vertical part of which is adjustably retained fiat against the forward face of plate I0 near its right end, said adjustable means comprising an'upper eccentric screw 3| and two lower 7 screws 32 (see Figs. 1 and 2) the latter passing through slots in the bracket 30. Adjustment of eccentric3I and screws 32 enables an operator to set the needle accurately or as needed to traverse the notch in the plunger I3. It will be understood of course that the needle point is directed toward the left.

33 is a thread extending from a spool (not shown) to a tension wheel 34 (Fig. 2) on the machine head, thence down to and through an aperture 38A in clamp 30, thence along the under side of the needle and upthrough its eye (see Figs. 2, '7, 8 and 9). i

35 is a flat metal block fixed transversely on the base plate 9 this block being L-shaped and having an arm 35A fixed in parallel relation to the inner edge and upright part of SE to slidably guide and retain the lower edge of plate I 0 therebetween. The central part of said transverse block is in the path of the needle and is notched at its under side to permit reciprocation of the needle therein, as at 35N in Fig. 6, where an X in L the notch indicates the needle position. During stitch forming operations'the needle point is reciprocated through said block and past it to the left and under an oscillatable finger plate 36 in co-operation with which the needle acts to make and inter-lock thread loops at the left side of the plunger where the needle emerges at each penetration.

The loop forming finger plate 36, hereinafter designated the looper is an elongated flat metal plate pivoted on and near the left end of base plate 9 as at 31 (see Figs. 1, 7, 8 and 9) and directed toward the right therefrom its latter end formed with a forwardly directed, tapered and suitably curved finger 36F which is oscillated across the path of the needle point and said entire finger plate is normally spring pressed rearwardly by any suitable'means such as the wire spring arm 38 fixed in a post 39 on base 9. The looper bears rea'rwardly continuously against a cam bar 48 fixed as at 4| on the lower inner face of the slide plate III, the said bar having a cam shoulder 403 near its right end. An upright peg 3GP on the looper engages said cam bar and as the plate I0 reciprocates the said pin rides the cam bar causing the looper to be oscillated when riding the shoulder 40S, thus oscillating the finger 36F across-the path of the needleand directly over it. This looper member may have reciprocating action instead of oscillating or any equivalent thereof.

Assuming now that the needle is about to make a penetration of the cloth 2 starting from extreme right position (Fig. 7) the looper 36F is at this time in extremeiorward position. The

needle first moves to the left to contact the cloth (dotted position Fig. 7) and plunger I3 is upholding the cloth in inverted U or V form in the path of the needle which penetrates the cloth to the right of the plunger then passes to left in the notch of the plunger anclpierces the cloth alsoin the path of the needle at the left side of said notch. This action brings the needle point, with two bights of thread, out to the'left as the looper F is moved rearward over the needle as peg 36P at this instant rides back on shoulder MS of cam bar 40. In Fig. 8 the looper finger is directly over the needle and in Fig. 9 it is clear of it rearwardly with its prong directed toward the upper adjacent side of the needle. As positioned in Fig. 9 the needle is at extreme left position, exposing one bight of the thread on top of the need'le and another bight under it.

Now when the needle starts back (to right) the thread on top of it is made slack and finger 3% starting forward enters between said thread and the needle and as the latter is retracted out of the goods the cloth is fedback one step by the feed bar 8, the finger 36F retains the thread on it in the form of an elongated loop (designated 33L in Figs. 7, 8 and 9) extending from the just completed cloth ,penetrationan'd forward, the forward end of said loop remaining on the finger and becomes slack when the looper starts to move back on the shoulder of the cam bar All and said loop is penetrated by. the next forward movement of the needle, the said thread loop being released from the finger by itsmovee ment to the right caused by the thread of the loop being guided tov the right by the needle contact and the edge of an aperture 35A in the transverse plate 35 and the rearward movement of the cloth by the feed fork. SS is a slot in plate 9 registering vertically with aperture35A just described (see Figs. 1 and 2).

Thus there are two strands of thread ineach cloth penetration, and one strand at the right from one penetration to the next,.while on the left is formed a row of interlocked thread loops 33L in a row parallel to the single strands, form ing the blind stitching. l l

The yieldable spring and roller actuated plunger it automatically compensates for vary ing thickness of goods passing over the plunger and the needle in any case penetrates the goods so closely to the underside of the goods that when the goods are removed from the machine the said points of penetration reveal little or none of the thread on said side. If thread is used of a color similar to the color of the goods the penetrations are to all intents and purposes invisible, a desirable feature in certain garment manufacture.

In Fig. 10 a folded hem of a piece of goods 2 is shown in the process of being blind-stitched and illustrating that the looped parts of the blind stitches are completely hidden when the goods are flattened out, and to the left in said Fig. 10 is shown a row of stitches exposed on a single thickness of cloth.

My presser foot has a slight vertical action corresponding to that in standard sewing machines and the feed bar and dogs have corresponding functions and are timed for proper action as is well known in the art.

In Figs. 2, 3 and 6, 9R designates a transverse rib on the under side of the presser foot plate 9 and in proximity to the plunger, this for the purpose of engaging and alining the goods being stitched in proper relation to the penetrating action or in other words it is an auxiliary medium for feeding and guiding the goods accurately.

Referring again to the vertically reciprocable plunger I3 and its yieldable upward pressure, said pressure as described, automatically engages any thickness or thicknesses of cloth or various kinds of cloth and the correct relative position or location of the notch in the plunger and the needle path therethrough is maintained.

This assures minimum exposure of thread on right side of the goods. It is clear that upward movement of the plunger brings the angle of its shoulder directly under the presser foot plate.

It will be readily understood that the stitching action of my device may be reverse to that shown, or from left to right and other mechanical details within the scope and spirit of my invention may be used.

I claim:

1. A blind-stitch attachment for sewing machines having a vertically reciprocable presser foot bar and a vertically reciprocable needle bar,

a cloth plate and table in common plane therebelow, a reciprocating feed bar and feed dogs actuated thereby and projectible through the cloth plate to contact and feed cloth rearwardly under the needle bar, the action of said f'e-ed bar synchronized with relation .to the needle bar; said attachment comprising over the cloth plate an elongated presser foot or" L-shape in cross section and removably fixed on the presser foot bar, a vertically disposed needle actuator plate slidably retained in parallel relation to the vertical part of the presser foot, means on the needle bar for engaging said actuator plate and imparting horizontal reciprocating movement to the said actuator plate, means on said actuator for adjustably and rigidly retaining a needle in parallel relation to it, at its base and in proximity to' the presser foot base, meansmounted at the under side of the cloth plate including an upright plunger projectible, upwardly yieldably in the path of the reciprocating needle to press goods to be stitched upwardly in ridge formation over the cloth plate, said plunger notched cen trally and traversed by the needle penetrating the goods at both sides thereof, said needle threaded to penetrate the goods with a double big-ht thereof and means mounted on the presser foot to engage the thread near the point of the needle and form successive interlocked loops of thread in a row on the surface of the goods where the needle point emerges.

2. The structure specified in claim 1, said plunger formed at its top end with a shoulder, said presser foot having a slot toward whichv said shoulder part is projected by the upward movement of the plunger.

3. The structure specified in claim 1, in which said actuator plate reciprocating means comprises a block fixed on the lower end of the needle bar of the sewing machine, said actuator plate being provided with an inclined slot slidably engaged by said block.

4. The structure specified in claim 1, in which the direction of reciprocating movement of the needle is transversely of the direction of the action of the feed bar and feed dog action of the sewing machine.

5. The structure specified in claim 1, and. an oscillatable cloth-feed lever member pivoted at the underside of the cloth plate near its outer end and extending toward and over the sewing machine feed bar, a feed dog member carried by the free end of said lever said feed dog provided with serrated parts projectible through and guided in slots provided in the cloth plate, and a slotted pivotal connection in said feed dog end part, a plate rigidly secured to the feed bar and having a variably adjustable pivot connection with said cloth feed lever intermediate the ends of the latter, to provide selective feed dog movement for stitch lengths as required.

6. The structure specified in claim 1, and an oscillatable cloth-feed lever member pivoted at the under side of the cloth plate near its outer end, extending toward and over the feed bar, a feed dog member carried by the free end of said lever, said feed dog provided with serrated parts projectible through and guided in slots provided in the cloth plate, and a slotted pivotal connection in said feed dog part with said lever, a plate rigidly secured to the feed bar and having longitudinally adjustable pivot connection with said cloth feed lever intermediate the ends of the latter, to provide selective movement of the feed dogs, the pivot of said feed dog lever comprising a vertically disposed headed pin longer than the pivot part of the lever journaled thereon, for the purpose set forth.

7. A blind-stitch attachment for sewing machines having vertically reciprocable presser foot and needle bars over a sewing table and cloth plate therein, a horizontal and vertically reciprocable feed bar under the cloth plate and means for synchronizing the feed bar movements with relation to the needle bar movements; a presser foot secured on the lower end of the presser foot bar, a vertically disposed actuator slidably retained in said presser foot in proximity to the needle bar, means connecting the needle bar and said actuator to provide horizontal reciprocation of the actuator, a needle holder on said actuator to hold a straight needle in horizontal direction and reciprocable accordingly in a horizontal plane, means for guiding and feeding cloth material under said needle on the cloth plate in a direction transverse of the needle action, plunger means for projecting said material upwardly in the path of the needle in an inverted V-form to cause double penetration of the material by the needle and means for retracting said plunger when the needle is withdrawn from the material, said needle fixed with its eye vertically directed, thread guide means for thread extending under tension from a source of supply and comprising the provision of a vertical aperture in the needle holder for the thread to extend downwardly therethrough thence longitudinally under the needle and upwardly through its eye to provide a double bight of thread in the penetrated material, a thread-loop forming finger member manipulated by the actuator plate to engage a bight of said thread over the needle when the latter projects through the material to form a thread loop and retain the same until the needle makes the next penetration, said loop retained in the path of the needle making the next penetration through said loop, and means for releasing said loop from the finger before next loop forming action.

8. The structure specified in claim 7, in which said loop-forming finger member comprises a horizontally oscillatable elongated member pivoted on the presser foot base its free end formed with a transversely arcuate, forwardly directed and tapered finger oscillatable in the path of the needle and over it to engage the thread on top of the needle as the latter is positioned thereunder and the finger point is actuated forwardly.

9. A blind-stitch attachment for sewing machines having vertically disposed, parallel and reciprocable bars, a horizontal table therebelow and cloth feeding means operating intermittently and in synchronization with said bars, a relatively rigid frame mounted on one bar, a needle retaining member slidably mounted in said frame and means mounted on the other bar to produce horizontally reciprocating movement of the needle member, said latter member comprising in part an adjustable needle holding clamp to hold a needle in horizontal direction over the horizontal table, means for feeding cloth rearwardly on the table under the presser foot in successive steps and selective length of movement, and cloth contact means mounted under said table and projectable upward at predetermined intervals to press the cloth upward in inverted channel shape and in the path of the reciprocating needle to provide double penetration of said raised cloth and means mounted on said presser foot member adjacent the extreme forward position of the needle to engage the thread on said needle and form said thread loop during the neXt penetrating action of the needle.

JOSEPH F. ARVER.

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