US3192885A

US3192885A - Automatic hemming unit

Info

Publication number: US3192885A
Application number: US131552A
Authority: US
Inventors: Roderick G Timm
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-08-15
Filing date: 1961-08-15
Publication date: 1965-07-06
Anticipated expiration: 1982-07-06
Also published as: GB958173A

Description

July 6, 1965 R. s. TIMM AUTOMATIC HEMMING UNIT Filed Aug. 15. 1961 5 Sheets-Sheet 1 July 6, 1965 R. G. TIMM AUTOMATIC HEMMING UNIT 5 Sheets-Sheet 2 Filed Aug. 15. 1961 July 6, 1965 R. e. TIMM AUTOMATIC HEMMING UNIT 5 Sheets-Sheet I 3 Filed Aug. 15, 1961 lllll Ill July 6, 1965 TIMM 3,192,885

AUTOMATIC HEMMING UNIT Filed Aug. 15, 1961 5 Sheet s-Sheet 4 July 6, 1965 R. e. TIMM 3,192,885

' AUTOMATIC HEMMING UNIT Filed Aug. 15, 1961 5 Sheets-Sheet 5 FIGJI. 1

production of T shirts, polo shirts and the like.

form the exposed face of the fabric.

j 3,192,885 Patented July 6, 1965 3,192,885 AUTQMATIC HEMMENG UNIT Roderick G. Timm, Harris Mills, Inc, 6 Johnes St, Newhurgh, N.Y. Filed Aug. 15, 1961, Ser. No. 131,552 21 Claims. (Cl. 112-2) This invention relates to an automatic unit for feeding successive flat work pieces to a sewing machine for the production of a hem along one edge of each of the successive work pieces. It is particularly concerned with the provision of a blindstitched hem along one edge of each work piece. The invention is of special utility in the hemming of relatively thin work pieces having a tendency toward curling along the edges. An example of the type of Work for which the machine is exceptionally well adapted is the hemming of the ends of sleeve forming sections produced from knit fabrics, such as are employed in the However, the invention has a broader application and is adapted for the production of exceptionally neat hems in a variety of types of articles and at various points in such articles. It may be used, for example, in the hemming of pockets.

Basically, the unit comprises a table structure having an L-shape top with a conveyor belt of suitable construction adapted to move along the surface of a platform mounted on the table top and extending longitudinally of the longer arm of the table top. At a suitable point along the forward side of the belt, i.e., that side toward the operator of the unit, there is provided a suitable folder adapted to automatically fold the forward-edge of the work piece into an S or a Z form for the production of the hem. The inward portion of the folder rests upon the belt, while the outward portion of the folder overhangs the edge of the belt and rests upon the platform. From the delivery end of the folder the work piece is fed beneath the pressure foot and into cooperation with the feeding mechanism of the sewing machine. This carries the work to and through the stitching zone at which suitable stitch forming mechanism serves to secure the hem portion of the fabric to the main body of thelatter and simultaneously apply an overedge line of stitching to conceal and protect the free edge of the hem. Just in advance of the stitch forming mechanism there is preferably pro vided an edge trimming mechanism which trims the free edge of the hem before it is incorporated in the seam.

In the preferred operation of the unit, the folder is adapted to deliver the Work piece to the stitch forming mechanism along a path which causes the needle of the stitch forming mechanism to pass its thread through a fold in the work piece so that the overturned hem portion is united with the main body of the fabric by a line of stitching which is not visible at the surface which will Thus there is provided a line of, blindstitching, and simultaneously an overedge seam is formed over the free edge of the fabric.

To facilitate and insure the proper folding of the fabric to produce the desired hem, and to enable the sewing machine to form the line of blindstitching, it has been found highly desirable to provide means for projecting streams of low pressure air across the edge of the work piece as it is being advanced through the folder. This not only facilitates the folding operation and overcomes the curling tendency of the edge of the Work piece, but it also assists in advancing the material through the folder. The latter is accomplished by reducing the frictional resistance to the movement of the fabric through the folder and by so directing the air stream that it has a component in the direction of advance of the work pieces. The provision of such air streams makes it unnecessary for the operator of the unit to exercise extreme care or skill in supplying the successive workpieces to the work table and conveyor belt, or to assist in advancing the work toward the stitch forming mechanism. This gives rise to the great advantage of eliminating the necessity of long training periods for operators of the unit and it also makes possible the employment of less skilled operators than are normally required for the production of neat hems of the character mentioned above with conventional sewing apparatus.

A special feature of the invention is the provision of a folder which maybe readily removed from and replaced in the region of the sewing machine without the necessity of employing any tools, such as screw drivers, pliers, or the like. The folder may simply be grasped by one hand and a spring catch removed by the other hand to enable the folder to be lifted from the sewing machine and the work table. This facilitates any adjustments which it may be found desirable to make in the folding attachment. For example, a single folder may be adapted to produce a hem which may vary between, say, one-quarter inch and one inch in width. If desired, a folder may be provided which will permit even greater variation in the width of the hem. Removal of the folder also facilitates its adjustment to accommodate work pieces of different thicknesses. In this connection, it may be mentioned that the forward or delivery end of the folder carries a member-that is provided with a V notch arranged to engage a retaining screw extending upwardly from an edge guide provided on the sewing machine. This edge guide may be adjusted laterally of the line of stitch formation to vary slightly the distance inwardly'of the fold line of the work that the needle will be passed therethrough. So also, an edge provided on the folder, and over which the work is automatically folded, may be adjusted laterally to provide a suitable space between such edge and the cooperating surface of the edge guide of the sewing machine, to allow free passage of different thicknesses of work between them. This eliminates the danger of jamming of the material between the indicated edge of the folder and the guide surface of the edge guide. It also guards against the provision of too wide a space between these surfaces which would result in the production of a seam that varies from point to point, to a slight extent, in its distance from the folded edge of the hem. 7

Since, as explained above, the delivery end of the folder is retained in fixed relation to the edge guide of the sewing machine, any adjustment of such edge guide will produce a corresponding adjustment of the position of the delivery ends of the foldproducing edges of the folder. Only a slight variation is permitted, through adjustment of the specified member. adjacent the delivery end of the folder, between the guide surface on the edge guide of the sewing machine and the cooperating fold edge of the folder. 'In the normal operation of the unit contemplated by the invention, the operator is simply required to apply the successive work pieces to the conveyor belt and a portion of the work table in a reasonably accurate position. capable of applying the work pieces in this manner atia rate to keep up with the substantially continuous operation of the sewing machine and the'conveyor belt. The operator very quickly learns how to position the work pieces so that a thread chain of only about one-half to three inches is produced between the trailing end of one work piece and the forward end of the. next work piece. Thus, with a sewing machine operating at a speed of say 4,000 r.p.m., a relatively unskilled worker can turn out a quite large quantity of hemmed workpieces in the course of a day.

Another special feature, of the invention is the provision of a knot detector in the line of transmission of It has been found that .an unskilled operator is for operation again very speedily.

the needle thread. The special arrangement for this purpose, to be herein described, involves the provision of a mercury switch on a member through which the needle thread passes. This arrangement is such that when the knot in the thread engages the member carrying the mercury switch, the member is rocked sufiiciently to close the switch and thus close a circuit through a buzzer or light to warn the operator of the presence of the knot, However, after rocking the member the knot is permitted to pass through and thus enable the continued supply of thread to the sewing machine. By locating the knot detector three or four feet away from the eye of the needle of the sewing machine, adequate time is given to the operator to throw a switch for stopping the operation of the unit or to simply rock the control treadle for the same purpose. As the operator becomes more skilled in the operation of the unit, he may be able to gauge the time required to complete the stitching of the work piece being seamed at the time the signal is energized and then stop the operation of the unit before the knot reaches the needle. Stopping of .the unit enables the operator to draw a knot cautiously through the eye of the needle, without thread breakage or other damage, and thus place the unit in condition Should the knot or other obstruction in the thread be too large to be drawn carefully through the eye of the needle, the thread may be broken adjacent the needle and the latter re-threaded to continue the operation of the unit. If desired, the mercury switch could be placed in the circuit of a relay adapted in a suitable manner to bring about the automatic stoppage of the unit.

Other objects, features and advantages of the invention will appear from the detailed description of an illustrative embodiment of the same which will now be given in conjunction with the accompanying drawings in which FIG. 1 is a perspective view of the major portion of the apparatus as seen from the front, i.e. the side on which the operator is stationed, looking toward the right and rear;

FIG. 2 is a perspective view of the complete apparatus, looking toward the rear and the leftend thereof;

FIG. 3 is a detail view, in perspective, showing the knot detector;

FIG. 4- is a plan view of the forward portion of the apparatus in the region of the work folding means and the sewing machine, with three work pieces shown in broken lines;

FIG. 5 is a cross-sectional view through the folder taken along the line 5-5 of FIG. 4, with a work piece shown in broken lines;

FIG. 6 is a cross-sectional view through the folder taken along the line 6--6 of FIG. 4, the work piece being shown in broken lines;

FIG. 7 is a perspective view of the special folder;

FIG. 8 is a perspective view of a work piece, showing the form which it assumes asits leading end approaches the downstream end of the folder;

FIG. 9 is a perspective view of a work piece after it has passed through the sewing machine;

FIG. 10 is a plan view of the throat plate of the sewing machine, showing the edge guide, the stitch forming mechanism and the work feeding mechanism in relation thereto; and

FIG. 11 is an elevational view of a portion of the sewing machine, showing the edge trimming mechanism and adjacent parts.

The embodiment of the invention herein disclosed is' particularly adapted for the automatic hemming 'of one edge of a series of work pieces successively and continuously applied to a conveyor by an operator of the machine. The hemmed work pieces, which are advanced automatically through the apparatus as they are sup plied one after another to the conveyor, are suited, for example, for the production of sleeves for T-shirts, polo shirts and the like. The entire apparatus is carried by a sturdy table or work support having an L-shaped top It) mounted upon an appropriate leg structure 11 adapted to be firmly retained in a set position in a mill. Disposed for movement along the top surface of a platform 1% mounted a suitable distance above the longer arm of the L-shaped table top 1 is the upper run of an endless conveyor belt 12. The lower or return run of the belt passes beneath the platform and along the upper surface of the table top. This conveyor belt may suitably be formed of canvas or other relatively coarse fabric adapted for frictional engagement with the major portion of the bottom face of the successive work pieces applied to the upper run.

Mounted on the shorter arm of the L-shaped table top is a sewing machine 13 of a construction adapted to produce a line of stitching along the folded hem, such as an overedge stitch, preferably of the two-thread type. If desired, however, the seam may be formed by a single thread or by more than two threads. The machine illustrated in the drawings, and which has been found exceptionally well suited for the purposes of the invention, is of the type sold by the Union Special Machine Company as style 39500F, or it may be of the slightly moditied style 39500-13. Both of these machines have stitch forming, work feeding and edge trimming mechanism of the general character disclosed in the patent to Wallenberg et al., No. 2,704,042, granted Mar. 15, 1955. For the formation of a two-thread stitch, the underlooper is a thread carrying element while the overedge stitch forming element is simply a spreader. Briefly, as shown in PEG. 10, the machine has a throat plate 13a over which the work is intermittently advanced by feed dogs 13]; in the manner disclosed in said Wallenberg et al. patent. The free edge of the folded work piece is trimmed in the region of the throat plate by a movable cutter head 13d (FIG. 11) having a cutter blade 13a adapted to cooperate with astationary blade 13 carried by the frame of the machine. For further details of the trimmer see the above-mentioned patent to Wallenberg ct al. As the work pieceis advanced by the feed dogs of the sewing machine it is brought into cooperation with the overedge stitch forming mechanism, comprising a curved needle 13g, an underlooper 1312 and an overedge looper or spreader 13 The machine is provided with an edge guide 13k (FIGS. 4 and 10) for guiding the folded edge of a piece of work to be hemmed, this guide being of the character disclosed in FIGS. 7-10 of the patent to Hale et al., No..2,959,227 granted Sept. 13, 1960. The small, overhanging head 14 of the machine, which carries the spring for applying a downward force to a presser foot 14a, is disposed at an angle to the work supporting surface of the machine, as shown in said Hale et al. patent. Then hem folder shown in said patent, however, is omitted from the machine embodied in the present invention and is replaced by a special hem folder 15 (FIG. 7) constructed in accordance with the present invention.

For driving the sewing machine, and also the conveyor belt, there is provided a motor and clutch unit 16 (FIG. 1), commonly referred to as a transmitter. This unit is mounted beneath the table top and may suitably be suspended from the undersurface of the table top by suitable brackets. A treadle 17 is rockably mounted on a rod or shaft 17a carried by the leg structures of the table support. By a suitable connection 17!) from the treadle to a lever 17c carried by the motor and clutch unit, a drive connection may be eifected from the continuously running motor to the sewing machine and conveyor belt. Thus a motor and clutch unit, of the type shown in the patent to Ingalls No. 2,739,251, granted March 20, 1956, may be provided between the motor and a pulley 17d on the clutch which is connected by a belt 17a with a pulley 17) on the main shaft of the sewing machine. The arm is adapted to be rocked downwardly by the connection from the treadle for the purpose of operating the clutch. When the treadle is operated, and the clutch is thereby engaged, the pulley 17d connected with the driven shaft of the clutch unit is rotated. This pulley is connected by the belt 17c with the combined handwheel and pulley 17 f secured to the drive shaft of the sewing machine. Thus, when the clutch is engaged the sewing machine will be driven at its usual high speed. When the pressure on the treadle is released by the operator, the clutch will be disengaged and the driven shaft of the clutch unit will be quickly stopped by the brake means shown in the Ingalls patent. a

The conveyor belt 12 should be driven at a rate corre spending with the rate of advance of the work by the feed mechanism of the sewing machine. This maybe accomplished either through an appropriate direct connection from the transmitter or through a suitable connection from the main shaft 18 of the sewingmachine. In either case, appropriate speed reducing mechanism 19 should be employed in the driving connections for the conveyor belt. As illustrated, the conveyor belt is driven from the main shaft of the sewing machine. This shaft, as shown at 18 in FIGS. 1 and 2, projects outwardly from the handwheel and pulley 17 The shaft 18 is connected with the input end of the speed reducing mechanism 19 which has an output shaft extending through the top of its housing. A pulley 20 is connected with the output shaft and this pulley is connected by a belt 21 with a pulley 22 adjustably mounted on a bracket 23 secured to the top of the table. A lever 24 pivotally mounted at its lower end on the bracket carries a stud 25, at an intermediate point, on which the pulley 22 is rotatably mounted. Lever 24 may be locked in adjusted position by a wing nut 24a. The belt 21 and the cooperating groove in pulley 22 are of V or trapezoidal formation in crosssection so that the adjustment referred to above, which tends to tighten the belt somewhat, will bring about some variation in the extent to which the belt enters the V groove in the pulley. In this way a slight variation is brought about in the effective diameter of pulley 22. By decreasing its effective diameter its angular speed of rotation will be correspondingly increased. It will be appreciated that it is not necessary to vary such speed of rotation to any great extent, since the speed reducing gearing or mechanism is adapted to bring about the desired coordination of the rate of advance of the conveyor belt and the rate of advance of the work pieces by the feed mechanism of the sewing machine.

Connected with the pulley 22, for rotation therewith, is a second pulley 25a which is connected by the belt 26 with a pulley 27, secured to a shaft 28 carried by suitable brackets 29 and 39 mounted on the table top. It will be observed that shifting of the lever 24 to tighten the belt 21 will simultaneously impart a corresponding slack to the belt 25 so that the pulley will impart a slightly greater linear speed to conveyor 12. Conversely shifting the lever 24 to loosen belt 21 will impart a tightening to belt 26. 1

and in turn will impart a slightly less linear speed to conveyor belt 12. Shaft 28 carries a roller 31 around which the delivery end of the conveyor belt 12 is passed in frictiorl driving relation. The opposite end of the conveyor belt is passed around a roller 32 secured to a shaft 33 preferably supported at its opposite ends by ball or roller bearing units 34 carried by brackets 35 mounted on the table top adjacent the left end thereof. Through the speed reducing gearing 19, and the appropriate adjustment of the pulley 22, the rate of advance of the conveyor 12 may be made to coincide with or have some slightly different relation to, the rate of advance of the work by the feed mechanism of the sewing machine. While the latter is intermittent and the conveyor movement is continuous, it has been found that the slight yielding of the needle and of the fabric being stitched is such as to compensate for this condition. In practice it has 6 been found desirable to have the rate of advance of the belt slightly less than the feed rate of the sewing machine, but the two rates may be made equal. It appears undesirable to have the belt advance at a greater rate than the feed rate of the machine.

Spaced from the edge of the top run of the conveyor belt 12, on the side thereof toward the operator, there is provided a guide 36 to assist the operator in properly applying the successive work pieces to the conveyor belt and its supporting platform. This guide is so positioned that if the edge of the work to be hemmed is placed in substantially abutting relation to the guide, the work piece will be properly alined with the folding, trimming and stitch forming mechanism. The guide may be in the form of an angle member having a vertically extending guide surface positioned in the manner explained, or it may merely be.in the form of a cord or wire, or even a line drawn upon the top surface of the platform 10a. It is not necessary that the operator use extreme accuracy in the placing of the work pieces on the'conveyor belt, since the trimming mechanism of the sewing machine will readily trim off a certain amount of the. free edge of each work piece as it is advanced to the stitch forming zone. Of course, it is desirable not to bring about the trimming of an excessive width of the fabric in this operation, but it is desirable to insure that a certain amount of the fabric will be trimmed off, to provide a straight edge of the fabric to be incorporated in the overedge blindstitch to be applied to the work.

In the use of the apparatus the operator will be seated in front of the long arm of the L-shaped table top at the I point where the treadle 17- is located. The apparatus will be set into operation by closing a switch 37 ,(FIG. 1) provided on a control box 38 beneath the table top, this switch serving to place the motor of the motor and clutch unit in circuit with a source of electricity. When the operator is ready to feed successive work pieces to the machine, the treadle 17 will be depressed to engage the clutch of the driving unit and thus bring about the driving of the sewing machine 13 and also the conveyor belt 12. Successive work pieces will then be applied to the conveyor belt with a portion extending forwardly toward the operator beyond the longitudinal edge of the belt onto a portion of the surface of the platform 16a. The conveyor belt will then carry the successive work pieces to and through the folder 15 and deliver them to the feed dogs 13b of the sewing machine. As each work piece is stitched to provide the overedge blindstitch seam, it will be carried toward 'the right by the conveyor belt while the sewing machine continues to operate and forms a thread chain between the trailing edge of the completed work piece and the forward end of the succeeding work piece. It has been found that relatively unskilled operators are able to apply successive work pieces to the conveyor belt, in the manner explained, at an adequate rate to insure that the thread chain mentioned will not exceed 2 or 3" in length.

As a succession of work pieces passes through the hem folding and stitching mechanism, the work pieces may be discharged by gravity from the delivery end of the conveyor belt 12 into a basket, or the like, for subsequent severing of the interconnecting thread chains and delivery to the next point of operation on the work pieces. If desired, suitable means may be provided adjacent the delivery end of the conveyor belt for cuttingthe thread chains and other means may be provided for stacking the individual work pieces as they are discharged from the conveyor belt. a

The improved folder 1S embodiedin the units of the invention will now be described in detail. In a typical construction it is about 16" long and comprises a pair of members 40 and 41 (see FIG. 7) which are connected together adjacent the receiving end of the folder by a bracket 42 which is permanently secured by welding,

.anaasss soldering, or the like, to the under surface of the member 41 and extends outwardly from the latter, toward the operator of the machine, then upwardly and then rearwardly at a suitable elevation, about 3", over the tops of the two

members

40 and 41. At its rearward end it is provided with an elongated opening 42a in a foot portion 42b engaged with the top surface of member 49, and a screw 420 is provided to secure the bracket to the members 4h. The arrangement is such that the receiving or left ends of the members, as seen from the position of the operator, are made relatively adjustable in a lateral direction to a slight extent by virtue of the elongated slot 42a. Adjacent the delivery ends of the

members

40 and 41 they are interconnected by a bracket 43 having two cooperating

parts

43a and 43b. lart 43a is secured by screws 43c, or the like, to the upper surface of the member 46, while the part 43d is secured to the under surface of the member 41 by welding, soldering, or the like. Each part of this bracket has a portion extending upwardly from the longitudinal edge of the member to which it is secured and has a portion extending horizontally over one or both of the members 4t and 41 at a distance 2" to 2 /2 above the upper surface of the latter. the

parts

43a and 43!) are arranged for adjustable connection, as by the provision of an elongated slot 43d in part 43b and a screw 432 passing through said slot and having screw threaded engagement with the horizontal portion of part 43a. This relative adjustment of the two parts of the bracket described provides for variation in the width of the hem to be provided in the work piece as it is fed through the sewing machine. The width of the hem may be varied between any suitable limits, such as A" to 1.

Member 40 is formed of two flat, relatively stiff strips of metal, such as brass. The upper strip has been designated 49 and the lower strip 40a, this extending slightly beyond the upper strip in the direction from which the work pieces approach the folder. Also, this upstream extension of the strip 40a is bent upwardly at a suitable angle to insure the passage of the work pieces beneath it as they are carried along by the conveyor belt 12. Between the two

strips

40 and 40a is a bar 46b, formed of any suitable material, which serves to retain the two strings 'in spaced relation, preferably about A" apart. The bar 40b is narrower than the strips 49 and dim and preferably has one edge flush with the outer or rearward edge of the two strips 4% and 443a, while its inner edge extends parallel with the forward edge of strip 49a, over which the work piece is folded in the manner shown in FIGS. 5 and 6. That portion of the strip 4% which extends from a point approximately beneath racket 42 to the delivery end of the folder is provided with an edge parallel with the two edges of the bar 4%. It is this edge over which the work is folded to provide the fold line through which the blindstitching operation take place. The corresponding edge of strip 49 is preferably spaced laterally toward the rear, as viewed from the position of the operator, a distance of about A" for about one-half to two-thirds of the length thereof from the receiving end of the folder. From this point on, this edge of strip 40 is gradually angled outwardly in the direction toward the operator, and adjacent the deliveryend of the folder it is disposed about A" or more forwardly, i.e. toward the operator, of the corresponding edge of strip 40a.

Member 41 is formed of a single strip of suitable metal, such as brass. It has its receiving end 41a curled slightly downwardly substantially into engagement with the top surface of the platform a. This is to insure that the work will pass upwardly over the top of the member 41 as it is advanced by the conveyor belt. Adjacent the receiving end of the folder the inner edge 41b of the member, 41 i.e. the edge away from the operator, is spaced laterally from the adjacent edges of the strips 46 and The horizontally extending portions of 40a. 7 However, at a point about two-thirds of the distance from the receiving to the discharge end of the folder, the inner edge 41!; of member 41 passes between the two

strips

46 and 40a and enters the slot provided between those strips to an extent depending upon the adjustment of the brackets 4-2 and 43a, 4312. It is the inner edge 41b of the member 41, in the region adjacent the discharge end of the folder, that determines the position of the upper fold of the S-folded edge of the work piece and thus determines the width of the hem to be formed.

It will be seen from the foregoing that as the work iece is advanced through the folder it rides beneath the bottom of the strip 49a and over the top of the member 41. A slight downward pressure is applied by the strip 4 3:: against the work piece to hold it against the conveyor belt 12, this pressure being only a fraction of the gravitational force acting on the folder. In the course of its advance it is first folded over the inner or forward edge of strip Mia, i.e. the edge toward the operator, and is then folded over the inner or adjacent edge 41b of the member 41 to provide the S-fold mentioned.

For retaining the folder in proper position in relation to the platform Etta, the conveyor beit l2 and the sewing machine 13, resilient means adapted to permit ready re moval of the folder are preferably provided. Such resilent means comprises a bracket 44, preferably formed of steel. This bracket has a foot portion 44:: which is adapted for slight adjustment in relation to the member -tl of the folder. For this purpose the foot portion 44a may be provided with enlarged or elongated openings arranged to receive the shanks of screws 4412 having threaded engagement with the members 4'9 and 4%. As will be made clear. by the description of other parts, this adjustment of the bracket 44 in relation to the folder insures proper action of the latter in dealing with work pieces of different thicknesses. it serves to provide proper clearance of the fold in the work piece between the forward edge of strip 40:: and the edge guide of the sewing machine. Bracket 44 has an upwardly extending branch and then a horizontally extending branch, substantially parallel with the bracket 43, and then a further downwardly extending branch which is twisted through an angle of and has its lower end projecting horizontally toward the delivery end of the folder. The outer end of the horizontal extension 440 is provided with a V-notch 44:! which is adapted to cooperate with a screw 44a (FIGS. 4 and 1(9) secured to the top of the edge guide 13k provided on the sewing machine. This edge guide may be of the character shown in the patent to Hale et al., No. 2,952,227, and is provided with a knurled screw member 13m (FIG. 10) for adjusting the position of the guide laterally of the line of stitch formation. It will be understood that the folder shown as mounted on the edge guide of the Hale et al. patent is omitted from the present construction, and the knee press connections for shifting the edge guide shown in said patent are also preferably omitted. The horizontal extension 4 is retained resiliently against the shank of the screw dds. If desired, the screw 44a may be provided with an enlarged head at its upper end which urges the end of extension 440 downwardly. By slight adjustment of the screw Me, if so constructed, the elevation of the discharge end of the folder may be varied slightly and a suitable downward pressure may be applied to the folded work piece just as it leaves the folder and is being delivered to the presser foot and work feeding mechanism of the sewing machine.

Toward the receiving end of the folder there is provided an upwardly extending rod 45 which is firmly secured in any suitable manner to the member 49 of the folder, but without any projection of the same through the bottom of the strip or member 494;. This rod is arranged to cooperate with a V-notch 46 .1 in a steel bracket member 46 which is secured to the top of the work table and has an upwardly extending branch and then a horizontally ex- 9 tending branch which extends over the platform 10a and conveyor belt 12 to the rod 45. The horizontally extending branch urges the folder downstream to retain V-notch 44d firmly against screw 44a. It will thus be seen that the folder is definitely held in a predetermined position, but in a somewhat resilient fashion, by the springy brackets adjacent the receiving and discharge ends of the folder.

To insure proper movement of the work pieces through the folder and to insure the proper folding of the edge portion of each work piece into the S-shaped fold mentioned, it has been found highly desirable to provide means tending to overcome the curling tendency of the fabric and to assist in urging the edge portion thereof into the desired S-fold. While various expedients could be employed for this purpose, it has been found very effective to employ meansfor blowing a stream or streams of air laterally across the folder as the work is being advanced. Thus a blower '47 having a small driving motor 47:: is arranged to blow a stream of air at a suitable rate, mainly in a direction transversely of the length of the folder but preferably slightly in the direction of advance of the work piece. Motor 47a is connected by an electric cord 47d with a switch box 47e that is in turn connected into the switch box 38. Thus the blower 47 may be turned on and off independently of the delivery of current to the motor and clutch unit 16. The blower is provided with an intake opening 47b which may be adjusted to vary the effective size of the opening and in this way vary .the volume of air that is blown toward the work. This enables adjustment of the stream of air so blown to conform with the characteristics of the fabric being subjected to the overedge blindstitching operation. The blower 47 is preferably also adjustable about its axis to vary the angle at which the stream of air is discharged through outlet 470 in relation to a horizontal plane. Generally it will be found desirable to direct the stream slightly downwardly from the horizontal toward the uppersurface of an extension 410 of the member 41, this extension being bent downwardly into engagement with the top of the platform 10a. The air striking this surface passes beneath the adjacent edge of the advancing work piece and blows it away from the side of the platform at which the operator is stationed and slightly forwardly in the direction of advance of the work. This serves to fold the fabric over a wire 48 as well as over the inner edge of strip 4ila, and tends to overcome any curling of the edge of the fabric. The wire 48 has one end connected by a screw 48a to the top of the bracket 42. From this point the wire is bent into a loop 48b extending toward the receiving end of the folder, to a point slightly beyond the receiving end, with the lower branch of the loop in a position above the receiving end of member 41 of the folder and extending toward the delivery end of the folder. At a point beneath the top of bracket 42, the lower branch of the wire 48 is positioned about /2" above the top surface of member 41 and it then extends in a substantially horizontal direction to a point at which it is connected with the member 40 by means of a screw 48c. As will be seen from FIGS. 4 and 7, the active portion of the Wire 48 over which the portion of the work piece to be hemmed is blown, extends across the gap provided between the

members

40 and 41 at an angle of about to the edge of the strip 40a over which the fold of the work to be blindstitched is bent. As the work advances, the stream of air discharged by the blower 47 continues to retain the free edge portion of the fabric over the wire 48 until it reaches a point slightly in advance of the retaining screw 48c. From about this point on, the fabric is forced by the inner edge of member 41 of the folder into the groove between the

strips

40 and 40a to complete the S-shaped fold. The folded edge of the fabric disappears from sight when it reaches a point in the region of the bracket 44, being then concealed within the folder.

It has also been found desirable to provide a second blower 49, driven by its own electric motor 49a and preferably provided with means for varying the intake opening -to adjust the volume of air blown against the work piece. Motor 49a is connected into the switch box 47e' by a cord 4% and receives current therefrom as the switch is closed. Blower 49 preferably has an extension 490 (FIG. 4), at its discharge end, which is adapted to direct at least a portionof the air into the space beneath the member 41 and into the channel formed between the latter and the upper surface of strip 40a, thus continuing to assist folding in the free edge of the fabric .over the inner or forward edge of the strip 40. This air stream also is directed slightly downstream of the folder and therefore assist in advancing the work piece. The air stream serves to facilitate the free movement of the work within the channel described and insures proper formation of the desired S-shaped fold with the free edge of the work extending slightly beyond, i.e. toward the operator, the lower fold edge of the S configuration, as shown in FIG. 6.

As the work piece is discharged from the delivery end of the folder it is passed over the throat plate 13a of the sewing machine and beneath the forward end of the usual presser foot of the latter. By appropriate adjustment of the screw 13m of the edge guide of the sewing machine, the proper delivery of the work to the stitch forming devices for production of the desired blindstitch may be insured. After the work piece has been passed between the presser foot and the throat plate, and thus positioned for cooperation with the feed dogs of the sewing machine, the work is largely advanced under the control of the latter. It is then subjected to a trimming operation to trim the free edge of the folded work piece to extend only slightly and to a uniform extent beyond the lower fold line of the work that has been advanced along the edge guide of the sewing machine. Subsequent to this, the stitch forming mechanism applies an overedge blindstitch to the work of the character shown in the patent to Riviere, No. 2,067,680, granted Jan. 12, 1937, and as shown at W in FIG. 9 hereof.

In FIG. 4 there is shown, in broken outline, three successive work pieces W, which are at different stages in the course of movement through the folder and the stitching region of the unit. In the actual operation of the machine, a skilled operator may be able to apply the successive work pieces to the conveyor belt to cause them to move through the folding and stitch forming means in a quite close spacing indicated in FIG. 4. A less skilled operator may require a greater distance between the trailing end of one work piece and the forward end of the next work piece.

FIGS. 8 and 9 show, in perspective, the condition of a work piece W at two different stages in its passage through the unit. Thus, FIG. 8 shows the work piece in the condition it assumes at the time the leading or downstream end approaches the corresponding end of the folder and is about to be introduced between the presser foot of the sewing machine and the throat plate thereof. As so shown, the work piece has a fold W" at its leading end which is ready to be advanced along the guide surface of the edge guide of the sewing machine. It also has an upper fold W which is formed over the inner edge 41b of the plate 41 of the folder. The rest of the work piece is shown in the progressive positions which the portion being folded assumes in the course of advancing through the folder. It will be understood that by the time the trailing end of the work piece reaches the discharge end of the folder, the work will have been provided with the two folds W and W" throughout its length. FIG. 9 shows the work piece W in the condition which it assumes after it has passed through the sewing machine. This 'is after the free edge extending beyond the fold W" has been trimmed in the manner explained and after the overedge stitching W has been applied thereto; also. the thread chains serving to connect the work piece with the next adjacent ones in a succession of such pieces have been severed.

it has been found important, in connection with an automatic system of the character described above, to provide some means for either automatically stopping the operation of the unit or for signaling the operator when some condition arises that leads to the production of defective scams or prevents the production of any seam. A major cause of difiiculties of this character has been found to be the presence of a knot or other enlargement in the needle thread. When such an obstruction in the needle thread is encountered, it cannot be drawn through the eye of the needle during the operation of the machine, with the result that the thread will break or, in some insome instances, the needle may be broken. The location of the stitch forming mechanism of the sewing machine is such that the needle thread is not clearly visible to the operator in the course of supplying successive work pieces to the unit. For this reason it is possible that some malfunctioning of the machine, such as the breakage of the needle thread, will not be quickly noted by the operator so that a number of work pieces may be incorrectly stitched, or not stitched at all, before the malfunctioning of the machine is noted. This, of course, entails considerable wastage of time and material.

In accordance with the invention, therefore, provision is made for promptly drawing to the attention of the operator the presence of a knot or other obstruction in the needle thread well in advance of its delivery to the eye of the needle. This is accomplished by the means to be described for giving either a visual or audible signal as the knot or other obstruction reaches a point three or four feet away from the needle. If desired, the arrangement may be such that the presence of the knot or other obstruction at the point indicated will automatically bring about stoppage of the sewing machine and the conveyor belt. However, since an operator must be present for the purpose of applying the successive work pieces to the conveyor, in the manner explained, there is some advantage in having the knot detectin means simply operate a signal so that the operator may permit the machine to continue to operate for a sufiicient length of time to bring about completion of the scam in the particular work piece that is passing through the stitch forming zone at the time the signal is given.

Turning now to a preferred embodiment'of the knot detecting feature of the invention, attention is directed to FIGS. 1 and 3. Thread is supplied to the needle and the underlooper of the sewing machine, respectively, from' two thread cones i! and 51. These are mounted upon a suitable stand 52 carried by the table top of the unit. Also carried by the table top and extending upwardly therefrom a substantial distance, say about 3 or 4', is a hollow post 53. Through this post there may be extended a portion of a cable 53a which serves to deliver current from a suitable source to the electric motor and clutch unit and to the two blower units described above. Adjacent its upper end, the post 53 carries a laterally extending bracket or arm 54 which is preferably bent, as indicated at 54a, to provide a V-shaped channel for the passage of thread Stla from the cone 5%, and is also bent at its outer end to provide a U-shaped portion 54b forming another guide passage for said thread. Intermediate the bent portions of the member 54 there is secured thereto a bracket 54c which carries a generally V-shaped member 54d adapted to rock freely about a rod 54:: carried by the bracket 54c. One arm of the member 54d is provided, adjacent its outer or lower end with a clamp 54 adapted to retain a mercury switch 54g. The portion of the thread extending between the

bent portions

54a and 54b of member 54 is passed through a triangular opening 54h at the lower end of the longer arm of member 54d. A slot 54-2 extends through this arm of member 54d at the upper end of the triangular opening 54/2. The arrangement is such that the thread will move freely 12, through the slot Edi, but when a knot or other enlargement on the thread is brought into cooperation with the slot 541, and will not pass through the latter, it will rock the member 54d in a clockwise direction (FIG. 3). This will cause the mercury switch 54g to be tilted downwardly from the clamp 54], rather than slightly upwardly as in the normal condition. The resulting flow of the mercury in the switch will close a circuit to be described. When member 54d is rocked to close the circuit, the longer arm will be in such a position that the thread is drawn downwardly frornthe slot 541' into the triangular opening 5412 so that the knot will pass on.

Thread 51a, drawn from the cone 51, is passed through suitable eyelets or other guides carried by a laterally extending arm 57a of a bracket or rod 57 extending upwardly from the support 52. The two threads Stla and 51a are passed downwardly from the

arms

54 and 57a, respectively, to a thread guide 55 carried by the sewing machine frame. This guide is provided with a plurality of openings or notches through which each of the threads may be passed, the thread Sfia extending from the guide to a tensioning device 56 carried by the sewing machine frame, and the thread 51a extending from the guide 55 to a thread tensioning device 58 carried by the sewing machine frame. It will be understood that other thread guides may be provided on the sewing machine for enabling proper delivery of the two threads to the needle and the underlooper of the sewing machine, respectively.

A battery 5% is mounted on the table top and has its terminals connected into a circuit for a suitable signaling device, such as a lamp or a buzzer 59a, or the like. A portion of this circuit is provided by a cable or pair of wires 6t extending upwardly along the post 53 and suitably clamped thereto by clamping elements 61 (FIG. 1). Two wires are thus carried to and along a portion of the arm 54 and they have their free ends connected with the terminals of the mercury switch 54g. It will be understood that other wires 60a extending from the battery will complete a circuit to the signaling device whenever the mercury switch is tilted in the manner explained, due to the presence of a knot or other enlargement in the thread being delivered to the slot 541'. When the circuit is thus completed the operator is warned of the presence of a knot, or the like, which will not pass through the eye of the needle. The location of the switch 54g at a substantial distance from the eye of the needle gives the operator ample time to act upon the warning and stop the operation of the machine, either by releasing pressure on the treadle or by operating the switch 37 If desired, a detent may be provided in the connections between the treadle and the clutch operating arm to hold the clutch engaged without the necessity of constant pressure on the treadle. When this is done, the machine may be stopped by simply releasing the detent.

In lieu of providing a battery for operating the signal means, a low voltage current for this purpose may be taken from the driving motor, in the manner frequently done for lighting purposes, and the like. Or current may be taken from the source which supplies the motor and a suitable transformer may be included in the circuit. A lamp 62, receiving current from any suitable source, is preferably provided to illuminate the sewing machine region of the unit.

It is believed that the mode of operation of the improved unit will be clear from the foregoing detailed description of an illustrative embodiment of the invention. The operator is seated in front of the unit in the region of the treadle 17, after the needle and looper have been.

properly threaded and the unit is ready for operation. She then places successive work pieces with their major portion on the conveyor belt 12 with the forward edge of each work piece substantially along the line of the guide 36. A portionof each work piece thus extends beyond the forward edge of the belt, i.e., toward the operator, a certain distance but is readily advanced along the top of the platform litia by the action of the belt. So

long as the operator is able to keep up with the speed of operation of the sewing machine and the conveyor belt, she retains the treadle 17 in the depressed position to maintain the sewing machine and conveyor belt in operation. The successive workpieces, spaced a few inches apart, are then advanced through the folder and delivered to the sewing machine in properly folded condition. The sewing machine then performs its edge trimming and overedge blindstitching operation on the successive work pieces and provides a small length of thread chain be tween the successive work pieces. Throughout this operation the

blowers

47 and 4% will be maintained in operation to overcome any curling tendency of the edge of the work and to assist the folder in performing the desired folding operation. As the successive work pieces are discharged from the sewing machine they are deposited from the delivery end of the conveyor belt into a basket, or the like, for subsequent handling. As hereinbefore indicated, the unit may be provided with thread severing means adjacent the discharge end of the belt so as to disconnect the work pieces from each other. Also, suitable stacking means may be provided for stacking the hemmed work pieces as they are discharged from the conveyor belt.

Whenever the knot detector is operated, by the presence of a knot in the needle thread, the operator stops the operation of the unit, either during the seaming of a particular work piece or upon the completion of the seaming of the work piece then going through the sewing machine if ample thread is available for this purpose between the needle of the sewing machine and the point at which the knot is detected by the device 54. After stopping the unit the operator draws the needle thread through the eye of the needle, or breaks it if necessary adjacent the needle and then rethreads the latter.

While a preferred embodiment of the invention has been described in considerable detail, it will be understood that various modifications may be made in the construction and arrangement of the several parts of the unit without departing frornthe invention as set forth in the accompanying claims. For example, the blowers may, if desired, be located beneath the table top It and provided with conduits from their discharge ends adapted to direct the streams of air in the manner described.

What is claimed is:

1. A method of providing a blindst-itch seam in a folded edge of a succession of work pieces which comprises applying successive work pieces in substantially fiat condition to .a supporting surface, advancing said supporting surface at the speed of formation of a blindstitch seam, and continuously advancing a succession of said work pieces with and by .the work supporting surface, folding an adge of each work piece which is parallel with the direction of movement of the latter to provide an S-shaped fold therein as the work piece is being advanced, and applying a line of stitching through one of the folds in each work piece as it is being advanced.

2. A method of the character set forth in claim 1 which includes the step of trimming the free edge of the folded work piece parallel with and adjacent the. lower bend of the S-shaped fold provided therein as the work piece is being advanced and prior to the application of said stitching thereto.

3. A method of the character set forth in claim 1 which includes the step of continuously blowing air laterally toward the edge of each work piece as it is being folded into said S-form.

4. A method according to claim 3 in which the air blown laterally toward the edge of the work piece is dirooted in two separate streams, the first stream being directed beneath the free edge of the work piece to fold it upwardly, and the second stream being directed into a region of the S-shaped fold to assist in forming this portion of the fold.

5. A method of the character set forth in claim 1 which includes the step of applying a force to the edge portion of the work piece wholly independently of the longitudinal movement of the work piece to cause said edge portion to fold over the main body of the work piece along a predetermined line and simultaneously off: setting the curling tendency of said edge portion of the work piece. 7 6. Apparatus for forming a blindstitch seam in a folded edge of each of a succession of work pieces which comprises a sewing machine having a throat plate, an elongated Work support in the plane of said throat plate, means incorporated in said apparatus for automatically 7 and continuously advancing a succession of work pieces in spaced relation along the surface "of said work support and delivering the same to and through the stitch forming zone of said sewing machine, means for folding one of the longitudinal edges of each work piece into an S-shaped fold as the work piece is being advanced by said advancing means toward the throat plate of said sewing machine, and means in said sewing machine for forming a blindstitch seam along a fold line of each work piece as it is being advanced.

7. Apparatus of. the character set forth in claim 6 having an edge trimming mechanism in advance of said seam forming means in said sewing machine adapted to trim the free edge of the S-shaped fold as the'work piece is being advanced.

8. In apparatus of the character set forth inaclaim 6, said folding means comprising a pair of relatively flat, elongated members disposed in parallel planes extending longitudinally in the direction in which said work pieces are advanced, said members of said folding means providing a plurality of edges at different elevations over which said work pieces are folded into an S-shaped cross section as they are advanced by said first recited means.

9. In apparatus of the character set forth in claim .8, the lowermost of said members of the folding means having its work engaging edge substantially alined with the direction of movement of the work pieces and having its delivery end disposed approximately in line with the line of stitching formed by said means for forming a blindstitch seam to present a folded edge of each work piece to said stitch forming means.

it). In apparatus of the character set forth in claim 9, the, uppermost of said members of the folding means having a work engaging edge extending laterally over said lowermost edge of the lowermost member to present a second' folded edge of each work piece spaced laterallyfrom the line of. stitching formed by said sewing means, and a third substantially flat member incorporated in said folding means above said pair of members for urging a portion of said work piece over'the work engaging edge' of said uppermost member.

11. In apparatus of the character set forth in claim 10, said members of said folding means being adjustably interconnected to enable variation in the extent to which said edge of the uppermost member presents a'folded edge of each work piece laterally of said line of stitching.

12. Apparatus'of the character set forth in claim 6 having means for applying a laterally outward force to the edge portion of the work piece while the latter is cooperating with said folding means for uncurling the edge portion of said work piece and directing the same along a predetermined path as it is being advanced through and folded by said folding means.

13. Apparatus of the character set forth in claim 12 in which said means for applying a laterally outward 14. Apparatus of the character set forth in claim 13 in which said means cooperating with said folding means comprises also a member providing a guide portion spaced above said fiat members of the folding means over which the edge portion of each work piece is folded by the stream of air, said guide portion extending at an angle to the longitudinal axes of the two fiat members of said folding means.

15. Apparatus of the character set forth ni claim 12 in which said means cooperating with said folding means comprises means for blowing tWo separate streams of air laterally toward the work and substantially in the plane thereof as :the work is being advanced, means providing. a guide above said folding means over which the free edge portion of successive work pieces may be blown by said blowing means, said blowing means being adapted to direct one stream of air against the work pieces adjacent the receiving end of said folding means and the other stream of air against said work pieces adjacent the dclivery end of said folding means.

16..Apparatus of the character set forth in claim 15 in which the first mentioned air stream is adapted to blow the free edge of said work pieces over said means providing a guide over said folding means, and said second air stream is adapted to blow a fold in said work pieces in a direction lateral to and slightly in the direction of movement thereof to facilitate advance of said fold along a fold forming edge of said folding means.

17. Apparatus of the character set forth in claim 6 having resilient means for urging said folding means into a position in which said folding means serves to direct the folded edge of each work piece into cooperation with said sewing machine for formation of the blindstitched hem therein.

13. Apparatus of the character set forth in claim'l'l in which said resilient means comprises a vertically resilient bracket member serving to connect the delivery end of said folding means with said sewing machine, said resilient means also comprising a horizontally resilient bracket fixed at one end and connected at its other end with said folding means adjacent the receiving end thereof and serving to urge said folding means toward said sewing machine.

19. In apparatus of the character set forth in claim 18, said folding means and said resilient brackets being so interconnected with each other'and with said sewing machine and the work support as to provide readily disengageable notch and pin connections enabling the ready application and removal of said folding means in relation to said work support andtsaid sewing machine by simply grasping and shifting-said folding means.

20. Apparatus for forming and seaming herns in a succession of work pieces which comprises a sewing machine having a throat plate,an elongated work support in the plane of said throat plate, said sewing machine and said work support being a stationary structure, means comprising an endless belt and driving means therefor for continuously advancing a succession of work pieces in spaced relation along the surface of said work support and delivering the same to and through the stitch forming zone of said sewing machine, means for folding one ofthe longitudinal edges of each work piece to provide .a hem as the work piece is being advanced toward the throat plate of said sewing machine, means for releasably attaching said folding means to said stationary structure and urging said folding means toward said throat plate, said attaching means including a plurality of resilient members, the latter having readily slideable pin and cooperating opening connections for retaining said folding means in operative position in relation to said stationary structure, said attaching means enabling said folding means to shift to a slight extent in a vertical dircction in relation to said stationary structure as Work pieces of varying thicknesses are advanced through said folding means and enabling removal of said folding means by simply grasping and lifting the same away from the stationary structure, means for directing a stream of air laterally toward said folding means substantially in the plane thereof for assisting in the formation of the fold therein, and means in said sewing machine for forming a seam along the fold in each work piece as it is being advanced.

21;. Apparatus of the character set forth in claim 20 in which said means for directinga stream of air has its discharge end adapted to direct said stream partially in ti c direction of advance of the work pieces.

References Cited by the Examiner UNITED STATES PATENTS 519,134 5/94 Parsons l12257 1,163,220 12/15 Corey 1l2l40 1,777,804 10/30 Miller 112-219 1,917,776 7/33 Sailer l12l40 1,941,452 1/34 Washburn 1l2l77 2,004,080 6/35 Roby l122 2,038,853 4/36 Popper 112124 2,278,042 3/42 Sailer 112143 2,534,999 12/50 Stevens ll2-219 2,630,772 3/53 Ederer ll2-2 2,797,656 7/57 Reid 112-2 2,840,019 1/58 Beasley 112203 2,910,028 10/59 Braun et a1. 112-2l9 2,950,520 8/60 Sonnino 28-64 3,099,970 8/63 Hite 1l22 JORDAN FRANKLIN, Primary Examiner.

THOMAS J. HICKEY, DAVID J. WILLIAMOWSKY,

Examiners.

Claims

6. APPARATUS FOR FORMING A BLINDSTITCH SEAM IN A FOLDED EDGE OF EACH OF A SUCCESSION OF WORK PIECES WHICH COMPRISES A SEWING MACHINE HAVING A THROAT PLATE, AN ELONGATED WORK SUPPORT IN THE PLANE OF SAID THROAT PLATE, MEANS INCORPORATED IN SAID APPARATUS FOR AUTOMATICALLY AND CONTINUOUSLY ADVANCING A SUCCESSION OF WORK PIECES IN SPACED RELATION ALONG THE SURFACE OF SAID WORK SUPPORT AND DELIVERING THE SAME TO AND THROUGH THE STITCH FORMING ZONE OF SAID SEWING MECHINE, MEANS FOR FOLDING ONE OF THE LONGITUDINAL EDGES OF EACH WORK PIECE INTO AN S-SHAPED FOLD AS THE WORK PIECE IS BEING ADVANCED BY SAID ADVANCING MEANS TOWARD THE THROAT PLATE OF SAID