US3448705A - Automatic sewing method and apparatus - Google Patents

Description

June l0', 1969 R. E. scHERR ET AL 3,448,705

AUTOMATIC SEWING METHOD AND APPARATUS Filed March s. 1965 sheet of 14 TOP DEAD' CE TE ING VI E EWING v v /B IAN P. CAM e f CA Nx-:Y J BRN 1" W Q June l0, 1969 r` R. E. scr-:ERR ET-AL 3,448,705l

AUTOMATIC SEWING METHOD AND APPARATUS Filed March s, 1965 sheet Z of 14 -PZF QJV m O 37 f\ MMM s /22 F|G.2F

#se Y OBE R June l0, 1969 R, E; SCHER ET AL 3,448,705

AUTOMATIC SEWING METHOD AND APPARATUS Filed Maron s, 1965 sheet of 14 June 1o, 1969 R, E, SCHERR ET AL 3,448,705

AUTOMATIC SEWING ME'HOD AND APPARATUS Filed March s, 1955 ATT NES June 10, 1969 R. E. sci-ERR ETAL AUTOMATIC SEWING METHOD AND APPARATUS Sheet Of 14 Filed March 3, 1965 June 10, 1969 R, E, SCHERR ET AL 3,448,705

AUTOMATIC SEWING METHOD AND APPARATUS Filed Maron s, 1965 sheet C of 14 Julie 10;.1969 R, E, SCHERR ET'AL AUTOMATIC SEWING METHOD AND APPARATUS Filed March 5, 1965 Sheet 4 '7 June l0, 1969 R, E SCHERR ET AL.v 3,448,705

vAUTOMATIC: SEWING METHOD AND APPARATUS v I L sheet 8 i of 14 Filed March 5. 1965 June 10, 1969 'R E SCHERR ET AL 3,448,705

AUTOMATIC SEWING vMETHOD AND APPARATUS sheet 9 of 14 Filed March 5, 1965 329 PIO lNvENTQRS l una E.. R

D 'Y k" June 10, 1969 R, E, SCHERR -ET AL 3,448,705

AUTOMATIC SEWING METHOD AND APPARATUS Filed March s, 1965 sheet /0 of 14 June 10, 1969 R, E, SCHERR ET AL v 3,448,705

AUTOMATIC SEWING METHOD AND APPARATUS Filed Meren s. 1965 sheet er 14 June 10, 1969 v R, SCHERR ET AL 3,448,705

ATOMATIC SEWING METHOD AND APPARATUS Filed Maren s, 1965 I sheet l er 14` June 1o, 1969 R, E, SRRERR E'TAL `3,443,705

AUTOMATIC SEWING METHOD AND APPRATUS Filed March s, 1965 sheet L3 of 14 NEEDLE DRIVE ENGAGE AND DISENGAGE POWER MEANS NEEDLE RAISEAND 10P DEAD CENTER PowER\MEANs June' 10, 1969 R, E, SCHERR ET AL 3,448,705

AUTOMATIC SEWING METHOD AND APPARATUS M .HN u.. M 2m md5 sewn m $2.5 EN. N NEHCJ 4 E 1339 E md5 v.. p 555m mmmum /m m 53.56.: SU MMA h s n P 553 9m@ Q m Q2, om @S Si x m @22mm Sm. j? om 02020 25m En@ .a to E E u t: SE @E555 52%. .n mag 5550.5 @Haw 52.` dwz 05.. Sm .5.. d l z Oo N 35% 5 1. s, 55s. z w md5. .dmv m S d Imm?. mv Sm .@om a M 55:52.. --.M w /7 m SJW t@ l2@ NQ@ mai 258 Patented June 10, 1969 3,448,705 AUTOMATIC SEWING METHOD AND APPARATUS Robert E. Scherr, Old Greenwich, Andre H. McHose, Ridgefield, Ian P. Campbell, Norwalk, and Carney J. Bryan, Stamford, Conn., assignors, by mesne assignments, to Ivanhoe Research Corporation, New York, N.Y., a corporation of Delaware Filed Mar. 3, 1965, Ser. No. 436,763 Int. Cl. D05b 23/00; D05c 3/02, 7/04 U.S. Cl. 112-2 39 Claims ABSTRACT OF THE DISCLOSURE Automatic sewing method and apparatus in which the fabric workpieces are supported upon a stationary work table having a low frictiona-l surliace, the workpiece being slid upon the surace by a movable clamp member which engages down upon the workpiece in a high frictional grip, the clamp member then being driven parallel with the surface while pressing down on the workpiece for moving the workpiece in accordance with the clamp movement. The clamp member is lifted from the w'orkpiece to release it after the sewing operation. Apparatus is shown for automatically lifting the needle and for cutting oit and clamping the thread after sewing. In one embodiment, a reciprocating arrester foot operates in timed sequence with the needle to hold small regions of the moving workpiece stationary while the respective stitches are formed, the desired predetermined path of stitches being formed a't high speed, and the arrester foot being automatically lifted to inactive position after the sewing operation.

The present invention relates to a fastening method and apparatus and more particularly to a fully automatic sewing method and apparatus for handling the work material and stitching at high speed along any desired predetermined path extending in two dimensions with reference to the work material suitable for automatically fabricating sewn articles, such as garment components, headwe'ar, Ifootwear, `and the like in an automation system.

In the past eltorts have been made to provide automatic stitching equipment for stitching along a path in two dimension. However, such prior apparatus have involved various serious operating pro'blems and difficulties and have been subject to severe speed and directional change limitations with the result that such prior apparatus have not been suitable for widespread commercial uses. Much of the prior equipment has been restricted to stitching along -a straight line path or a substantially straight line as advanced -by the intermittent bitching action of a lfeed dog so that only a limited amount of directional change in the stitching path could be accommodated at the norm-al stitching speed. In most instances a person was required to handle the work material during stitching or to prepare the Work material to place it in holding tix-tures or 'to control the mechanism during stitching, so that the prior mechanism were not actually fully automatic in use and were slow in operation. Prior apparatus which was intended to adv-ance the work material automatically for stitching along a path in two dimensions has operated on the principle of intermittent motion of the whole work material resulting in rapid wear and breakdown of the equipment due to the large inertial :forces and vibration arising from the stop and start motion of the whole work and associated equipment, and this stop and start motion has necessitated slow over-all stitching progress.

It is an object of the present invention to overcome the diiculties and problems of the prior art equipment economically and practically to provide a method and apparatus for fully `automatically handling the work nraterial and stitching the work material at high speed along any desired predetermined path in two coordinates.

' Among the many advantages of the method and apparatus disclosed herein -as illustrative of the presen't invention are those resulting from the fact that the work material as a whole is automatically handled and is propelled continuously 'by a force which is distributed over a substantial area of the work material near the desired predetermined path to be sewn so as to cause the work this localized region is released to be reaccelerated by the resilience of the material which was stressed in the region and by the increased tangential force being applied to it, so that ths local region quickly re-sumes its movement in synchronism with the work material as a whole. Then the next successive small localized region of the work material is briey arrested while the needle i-s passed through this region, after which it is allowed to reaccelerate and to resume its movement in synchronism with the work material as a whole, and so forth.

iAdvantageously, Ithe present invention enables the stitching operation to start at the edge or at any interior point in an expanse of work material, and the stitching automatically progresses at a high rate of speed along stra-ight lines and around bends and abrupt changes in direction to produce the desired path of stitches extending in two coordinates in a manner suitable for automatically fabricating parts and components of garments and the like in an automation system. Also, the illustrative embodiments of this invention enable the automatically provided stitching patterns to be quickly changed for different production runs to make different articles or components.

As used herein the term work materia is intended to mean the fabric, cloth, felt, canvas, leather, sheet or like goods upon which the stitching work is performed. This term is intended to include all such types of goods able to accommodate small amounts of `distortion in the plane of the goods themselves, regardless of whether the material of the goods is in one piece or multiple pieces, one layer or multiple layers, regardless of whether the goods are woven, non-woven, felted, in sheet form, porous, pertorate or imperforate, natural or synthetic or blended.

The term stitching along a path extending in two dimensions (in two coordinates) is intended .to mean that the path o-f the stitch-es in the work material can be defined with respect to the general plane of the work material in terms of two coordinates, and regardless of whether lthe work material itself :as la whole is planar or non-planar or is ysubsequently used in a plan-ar or nonplanar form. `In other words lthe stitching path may include straight-line segments, curved segments, |angles, abrupt changes in direct-ions, spirals, cusps, and the like.

In 'this specification and in the :accompanying drawings are described and shown a fully automatic, high-speed stitching method and apparatus as illustrative embodiments of the present invention, but it is to be understood that these examples are not intende-d to be exhaustive nor limiting of the invention. These illustrations are given so as to disclose the linvention fully and clearly -to those skilled 'in the lart tand so that the reader will appreciate how this invention can be adapted and modied in various Iforms, each as may be best suited yfor the conditions of a particular usage.

The various tobjects, :aspects yand advantages of 'the present invention iwill lbe vmore fully understood from la considerati-on tof the following ldescription in conjunction with the accompanying drawings, lin which:

FIGURE 1 is a perspective view with certain parts schematically shown for illustrating automatic I.highspeed stitching methods and apparatus embodying the present invention lfor stitching along a path extending in two coordinates;

FIGURE 2 is a sectional view taken along the line 2--2 of FIGURE 1 and shown on enlarged scale;

FIGURES 2A and 2B are sectional views corresponding Iwith FIGURE 2 and showing certain steps in a method embodying the present invention and illustrating the parts in -successive operating positions;

FIGURES 2C 2D, 2E and 2F are sectional views on an enlarged scale 'and illustrating modified steps in the method;

FIGURE 3 is a perspective view of a tfully auto-matic stitching system which is illustrative of the present invention, with certain parts being schematically shown;

FIGURE 3A is a sectional view taken along the line 3A-3A of IFIGURE 3 and shovm on an enlarged scale to illustrate details of an anti-backlash brake;

FIGURE 4 is a top plan view olf portions of the system of EIGURE 3;

FIGURE 4A is a partial sectional view taken along the line 4A-4A olf FIGURE 4 and showing arm lifting means;

FIGURE 5 is a side elevational vie-w of the sewing machine and associated apparatus of FIGURE 3 drawn on an enlarged scale with certain parts cut away or shown in section;

FIGURE 6 is 'a s'ide elevational view corresponding with FIGURE 5 and showing certain apparatus which was omitted from FIGURE 5;

FIGURE 7 is an end elevational view of the sewing head of the machine as seen from the direction 7-7 of FIGURE 6 and shown on enlarged scale;

FIGURE 8 is a view corresponding with FIGURE 7 and showing a different position of the parts in their cycle of operation;

FIGURE 9 is an elevational view partially in section of a portion of the control mechanism, being a view as seen along 4the line 9-9 of FIGURE 6 and shown on enlarged scale;

FIGURE 10 is a sectional view of a portion of the drive taken lalong the line 1'0--10 in FIGURE 5 and shown on enlarged scale;

FIGURE 10A is a side elevational view of the angular phase adjustment mechanism for adjusting the relationship between needle movement and intermittent fwork region arrester;

FIGURE l1 is a sectional View taken along the line 11-11 of FIGURE 6 and showing a portion of the control linkage;

FIGURE 12 is an enlarged sectional view of a portion of the sewing machine drive and contro1 mechanism as also seen in FIGURE 3 and as shown at the extreme left in FIGURE 6;

FIGURE 13 is an end elevational view of the mechanism of FIGURE 12;

FIGURE 14 is a perspective view of the top thread cut-off and clamp mechanism;

FIGURE 15 is an enlarged sectional view alo-ng the line 15 of FIGURE 14 showing the thread cutter elements;

FIGURE 16 is similar to FIGURE l5 and illustrates a subsequent step in the cut-off and thread clamping operation;

FIGURES 17, 18, and 19 are elevational views illustrating the thread cut-off mechanism at successive stages of operation;

FIGURE 20 is a top plan view of the drive disengage and needle raise and lock-up mechanism; and

FIG-URE 21 is a schematic circuit diagram of the electrical control and operating circuits.

IReference to these drawings in detail is made in the following description, and corresponding reference numbers are used to refer to corresponding elements and components throughout the drawings.

GENERAL DESCRIPTION OF HIGH-SPEED AUTOMATIC STITCHING METHOD FIGURES 1, 2, 2A and 2B show the process of automatically handling and stitching the work material W at high speed in accordance with the present invention. The work material W is illustratively shown, for example, as being a plurality of layers of fabric 21, 22 and 23 in part of a garment. The work W is continuously moving over a work table 24, so as to pass by a reciprocating needle 25 being driven by drive means 27 and this automatic high-speed stitching process produces a line of stitches S extending along a predetermined stitching path in two dimensions in any desired pattern in the work W, for example, such as the path P to be traced by the stitches. The surface of the Work table 24 is smooth so as to facilitate -sliding of the work thereupon.

In this process a distributed driving force F is continuously applied to a relatively large area of the Work material W near the stitching path for continuously moving the work as a whole over the table 24 during the stitching process. Small localized regions -R of the work centered about the successive points of needle penetration are -very briefly stopped by applying an arresting force in opposition to the applied driving force in the local region, and the needle is passed through the material .at the center of the small arrested region of the fabric. When the material being sewn is cloth, then the whole remaining area of the work material W remains in continuous movement even though the small localized region R has very briey been stopped, and so this local region temporarily lags behind the general movement of the overall area of the Work material W. There is a consequent, brief localized distortion of the work which is accommodated by the localized yielding. When the material being sewn is stiii, then the arresting force serves to stop a larger area. As soon as the stitch is completed, the work material is released and accelerates up to speed so as to move ahead into synchronism with its initial movement as a whole.

In order to provide the distributed driving force F for continuously propelling the work material W, in this illustrative embodiment of the invention there is a lightweight, rapidly movable work clamp 2-6 pressing down through a resilient coupling medium lfirmly upon the work. This work clamp 26 includes a rigid frame 28 and a resilient coupling medium 30 attached to the frame 28 and positioned between this frame and the work and extending along closely adjacent to the stitching path P. This resilient coupling medium 30 is compliant in compression so as to accommodate changes in thickness of the work material W, for example, such as the transition from the 'area where the two layers 21 and 22 are present to the area where the third layer 23 also is present, as shown in FIGURES 2, 2A and 2B. This resilient coupling means 30 is also compliant in shear so as to accommodate the distortion which occurs when the work is arrested in its motion with respect to the rigid frame of the clamp, as shown in FIGURES 2A and 2B.

In this example the clamp frame 28 is formed of light-weight metal, such as aluminum having cut-out areas 31 so as to lighten it while maintaining its rigidity, and the resilient coupling medium 30 is a strip of elastic springy substance such as sponge rubber, extending along closely beside the stitching path P. The edge 32 of the clamp frame 28 is uniformly offset laterally from the stitching path P along the length of this path by a small olset distance, to place the edge 32 of the clamp frame as close as practicable to the needle. The coupling medium 30 projects out slightly beyond the edge 32 so as to extend along even closer to the stitching path P as seen most clearly in FIGURE 1, for reasons as explained further below.

In this illustrative example for purposes of briefly arresting the localized region R of the work material W, there is an arrester foot 34 reciprocated up and down by drive means 35. In this example the arrester foot 34 has a narrow annular -bottom surface closely surrounding the needle .25 for engaging the top surface of the work just prior to entry lof the needle into the work, as seen in FIGURE ZA. During the formation of a stitch as shown in FIGURE 2B, the point of the needle 25 passes down through a throat opening 36 in the table 24, and the needle thread 37 is engaged .by a bobbin thread 38 carried by a bobbin mechanism below the table 24. This bobbin mechanism is of standard type and so it is not described herein in detail. The resulting stitches S as shown in FIGURES 2, 2A, `and 2B are of the type identi-t fied as Stitch Type 301 in the Federal Standard No. 751 dated Aug. 14, 1959, and entitled Federal Standard- Stitches, Seams, and Stitchings lwhich was published by the General Services Administration. This stitch Type 301 is commonly called a lock stitch, and when this stitch is properly formed or set, the needle thread and the bobbin thread engage each other approximately midway through the thickness of the work material.

The annular .bottom surface of the arrester foot 34 holds the local region R of the work firmly down against the table 24 in the immediate vicinity of the throat opening 36. It is possible to use a variety of surfaces underneath this foot 34, depending upon the surface characteristics ofV the Work material. For example, when it is desired to increase the arresting holding effect upon the region R of the lwork, this may be done by roughening the bottom of the arrester foot 34 by knurling. When it is desired to exert a lower pressure per unit area on the work material beneath the foot 34, then the annular area of the foot may be increased and its arresting effect is provided by using a tough bottom layer of material having a high coeicient of friction such as tough plastic material and the like. As soon as the needle has 'been withdrawn from the work, then the arrester foot 34 is raised away from the work, releasing the region R for reacceleration as described further below.

The arrester foot 36 also acts as an anti-flagging element. That is, it holds the work down during the upstroke of the needle 25 so as to prevent the friction of the withdrawing needle and thread and the lifting effects of setting the stitch from curling or deflecting upwardly the work material. Any agging of the work material is undesirable as it prevents the proper setting of the stitch on the upstroke [of the needle.

At the conclusion of the desired stitching pattern, the needle 25 is automatically stopped in its top position by a top dead centering mechanism 33, and the arrester foot 34 is lifted and held up higher than during stitching so as to .be elevated completely above the clamp 26 -by means of an arrester foot lift mechanism 39 also actuating the thread cutter 41, all of which steps are described in detail further below.

During the stitching process the work clamp 26 is moved continuously with relative components of motion in two directions so as to provide the exact direction and rate of motion of the work past the centerline CL (FIG- URE 4) of the needle for producing stitching along the desired path P. The work clamp 26 is connected to lightweight, high-speed drive means, generally indicated at 40, for producing the two components of motion. For

clarity of illustration the two components of motion are indicated as being in an X and Y coordinate system.

It is our intention to reduce the mass of the work clamp 26 and its drive mechanism while maintaining a high degree of rigidity so as to move the work material rapidly and accurately to produce a continuous stitching rate throughout the pattern which is equal to the maximum possible stitching rate available from the fastest present day industrial sewing machines, except for a very brief engagement period at the beginning or end of the stitching pattern which amounts to two or three stitches. The illustrative embodiments of the invention produce a stitching rate of 100 stitches per second with a sewing machine having a standard rotary bobbin with a horizontal axis, but it will be appreciated that these methods and apparatus are capable of operating at considerably higher speeds if and when faster sewing machines become available. =In the drive system which provides these two desired results of minimum mass and maximum rigidity relative to mass, in this illustrative process the clamp 26 is supported and driven by a hollow, lightweight, spar-like arm 42. Thus, the movement of the work clamp 26 is definable in terms of the angular movement of the arm 42 about its instantaneous center of revolution and the movement of this arm 42 in the direction parallel to its own length, i.e. in terms of angular and radial displacement, and the X and Y components of movement of the work past the centerline of the needle are appropriately provided thereby.

When the stitching pattern has been completed and the thread cut, then the work clamp 26 is quickly moved to the desired delivery point on the work table 24 and iS elevated so as to disengage the resilient coupling means 30 from the work to release the completed work at that delivery point. While the work clamp is still elevated it is brought into relative position above a new piece of Work material at a work receiving point and then is abruptly lowered onto this new work material at this point and is quickly moved back to the initial position with respect to the needle CL so as to begin the stitching pattern. It is an advantage of this method and apparatus that the position at which the work is received may be the same as the position at which the completed work is delivered, or these positions may be spaced apart, as desired in a particular application.

It is to be appreciated that the handling of the work material during stitching and the stitching process are fully automatically Carried out. The new pieces of work material may be delivered manually or automatically to the receiving point on the table and the completed work may be manually or automatically removed from the delivery point on the table. If desired the delivery and receiving points on the table may be closely adjacent, coincident, or Widely separated; also, alternate delivery points and pick-up points may be utilized in sequence in successive cycles.

This stitching method and apparatus las described is capable of stitching a pattern at a rate of 100 stitches per second. Ultra-high speed photographs taken at the rate of eight thousand frames per second during the stitching process show that at these very high rates of speed slight deformations of the arm 42 do occur, but fundamentally the arm 42 and clamp frame 28 are in continuous movement while the desired region R of the work is arrested very briefly and then reaccelerated. The reason for mentioning what is seen under ultra-high speed photography is to emphasize the successful operation of this apparatus so that in fact suitable stitching of complex patterns is i produced at a rate of 100 stitches per second.

Thus, the amount of mass which is arrested and reaccelerated during and after the formation of a stitch is not significantly greater than the mass of the small localized region R of the work material plus a portion of the adjacent resilient pad 30. Moreover, it is the local spring constant of the work material itself and the resilience of the pad 30 which produce the reacceleration of the region R while the work-propelling apparatus is in continuous movement. By virtue of this method the stitching process is automatically carried out continuously at a high rate of speed and a high over-all production rate is provided.

It is to be noted that there are industrial sewing machines which are now in use which have a top speed rating of 100 stitches per second. In these machines the work itself is hand fed by an operator, `and the operator slows the machine down when turning corners in the stitching pattern and when making curves and changes in direction. Consequently, the peak speed of 6,000 stitches per minute is obtained only for very brief periods, if at all, and then only during long straight runs r gradual curving portions of the stitching pattern. Thus, the average speed or resultant production rate is far below the peak speed which is only brieiiy, if at all, obtained.

In the stitching method described above, when used t0 form a wide variety of useful stitching patterns, we have found that the full speed of 6,000 stitches per minute can actually be maintained throughout the formation of the Whole pattern, except for the brief engagement period at the very beginning and very end of the pattern. Moreover, the work material is automatically handled throughout the entire stitching operation.

In the stitching method described above the local region R of the work material is arrested during passage of the needle therethrough, and in this embodiment of the method the region R is arrested by the reciprocating arrester foot 34. We have found that this process works to advantage for a wide variety of types and thicknesses of work material. For example this process works to advantage with thin very compliant Work material such as one or two layers of thin skirt cotton and also works to advantage with fairly thick stiff material such as three or four layers of 14-ounce blue -denim material, and the like.

We have also found that the local region R of the work material can be arrested by the needle acting solely by itself in entering and passing through the material, as shown in FIGURES 2C, 2D and 2E, if certain precautions are taken and if certain criteria are met. An advantage of operating without the `arrester foot 34 is that the method and apparatus are made correspondingly simpler, and hence the apparatus is less expensive and easier to maintain. When the needle alone is used precautions are taken to prevent pressure of the work material from occurring against the side of the needle tending t0 deflect it against the side of the throat opening 36 and to prevent flagging, as set forth below.

When the arrester foot 34 is omitted, then the resilient and distributed compliant shear force F is applied to the work material quite close to the stitching path to minimize flagging. In this example this is accomplished by extending the edge of the shear compliant coupling medium 30 out from under the edge 32 of the clamp frame 28 so as to be offset from the stitch path P by a very small amount which is sufficient to clear the needle. This resilient medium 30 now serves the function of preventing the work material from iiagging upwardly as the stitches are set.

However, the close proximity of the resilient ymeans 30 increases the mass present near the needle and thus tends to raise the side loading on the needle. The exact amount of offset between the edge of the resilient coupling medium 30 and the path P of stitching to be used in a particular case depends upon the upward exibility of the work material W and also upon its own shear compliance. More tlexible work material requires less offset of the medium 30 to prevent agging, and material with more shear compliance will impose less side-loading upon the needle.

In actual practice these two criteria usually dovetail because more flexible work material is usually also more compliant in shear, and vice versa. If circumstances do not work out in this Way in some cases, then the arrester foot 34 may be used. In the absence of the arrester -foot the width of the coupling medium 30 may be reduced below that which is used when the presser foot is present, so as to avoid side loading on the needle. This narrow strip 30 is indicated at N in FIGURES 2C, 2D and 2E, which is narrower than that shown in FIGURES 2, 2A and 2B.

It is desired to avoid stubbing of the arrester foot 34 against the oncoming edge of a layer of Work material. This can be accomplished in various ways, but Where the problem of stubbing does not occur, then these expedients are not needed. For example, as shown the arrester foot has an upwardly sloping surface surrounding its annular bottom surface. Thus, it does not stub itself against the edge of an approaching additional layer, such as the layer 23 (FIG. 2), but jumps readily upon this oncoming layer, regardless of the direction at which the work approaches the arrester foot. Another way to avoid the stubbing etfect is to increase the up-stroke of the foot 34. Where the stitching pattern includes several changes in the number of layers 21, 22 and 23 present, then we have found that the first stitch in an approaching new layer or last stitch in a receding previous layer is made slightly neater in appearance by use of the arrester foot 34, but this difference is usually not significantly noticeable.

In the following description the arrester foot 34 is shown, but it will be appreciated that it and its operating and control apparatus may be omitted when the above criteria vare met and the precautions are taken as outlined above in detail.

GENERAL DESCRIPTION OF FULLY AUTOMATIC STITCHING SYSTEM As shown in FIGURES 3 and 4 the work clamp 26 and arm 42 are driven by a pair of lightweight triangular cam follower levers 44 and 45 driven by a pair of cams 46 and 47 mounted on a common vertical shaft 50. The levers 44 and 45 are disposed on generally opposite sides of the cams 46 and 47 and are arranged and connected so that the lever 44 produces mainly movement of the spar arm 42 in a direction parallel to its own length while the other lever 45 mainly produces angular movement of the arm 42 about the pivot 51. The drive lever 44 has a xed pivot 52 forming the f'ulcrum and has an intermediate follower roller 53, so that it is a lever of the third class and produces velocity multiplication at the pivot connection 51 with the spar arm 42. Consequently, the arm 42 is moved in a direction lalong its length (X direction) at a higher rate of speed than that imparted by the cam 46 to the roller 53.

The drive lever 45 has a cam follower roller 54, a pivot connection 55 to a cross link 56, and an intermediate xed pivot 57 forming the fulcrum. Thus, it is a lever of the first class and las shown has approximately equal lever arms to provide a velocity at the pivot connection 55 which is approximately equal to that imparted by the cam 47 to the roller 54. This velocity is transferred by the cross link 56 to a pivot connection 58 on the arm 42. The arm 42 itself is a lever of the third class with respect to movement about the pivot 51 imparted by the link 56, and hence there is a movement of the end of the arm 42 perpendicular to its length (Y direction) which is at a higher rate of speed than that imparted by the cam 47 to the roller 54. Advantageously, this arrangement produces velocity multiplication with respect to both coordinates of motion X and Y that are substantially equal. Consequently, the cams 46 and 47 may be of substantially the same over-all size for a wide variety of stitching patterns, thus minimizing the over-all sizes and ymasses of the levers, link 56 and arm 42 while enabling large pattern areas to be sewn at high speed.

The hollow spar arm 42 is tapered down toward both ends and has a maximum width near the pivot connection 58 to resist bending stress where the lateral thrusts are imparted. The triangular levers 44 and 45 arelhollow, and the cross link 56 is tubular to provide maximum rigidity to mass ratio.

In order to hold the - follower rollers 53 and 54 against their respective cams, powerful forces of substantially constant magnitude and directed inwardly generally toward the shaft 50 are applied to each lever at a point adjacent to the follower roller. For example, in this apparatus shown these forces are provided by strip springs 60 and 61 of the type which are self-winding on drums to generate a generally constant tension force regardless of extension. Such strip springs are available commercially under the trade designation Negator from the Hunter Spring Company of Lansdale, Pa. The rotating dru-ms of these springs are mounted on the machine frame as shown in FIGURE 4, and the ends of the spring strips are connected to flexible cables 62 and 63 extending -upwardly over pulley wheels 64 and 65 and then inwardly and around pulley wheels 66 which are rotatably mounted 0n the shaft 50. These cables then extend out to anchoring straps 67 on the respective levers 44 and 45.

During rotation of the cams 46 and 47, whenever one of the follower rollers 53 or 54 has just passed over a high spot or lobe on the cam and starts descending, then there is a tendency for the follower roller to try to accelerate the cam as a result of the force produced by the springs described above. The elect of this force would be to take up suddenly any back lash present in the gear train which drives the cam shaft 50, causing an undesirable jerk in the movement of the work clamp 26.

To prevent the cam movement from being influenced by the forces of the follower rollers 53 and 54 bearing against them and thus reacting against back lash in the drive gearing, suitable braking means are provided. For example, there is a large diameter disk caliper brake 69 providing a constant drag force upon the shaft 50v so that any back lash present is always taken up in the same direction with respect to the rotation of the shaft 50.

As shown in FIGURES 3 and 3A the caliper brake 69 includes a large thin metal disk 120 secured to the lower end of the shaft 50. A pair of opposed braking pads 121 and 122 of automobile brake lining material are pressed against opposite surfaces of the perimeter of this large disk. The lower brake element 121 is held by an adustable screw member and hand wheel 123 mounted in the machine frame. The upper brake element 122 is pressed by a compression spring 124 and 'is held by an adjustable screw member and hand wheel 125 mounted in the frame. Equal effective pressure is exerted by both brake elements 121 and 122 even though only one spring 124 is used, because the large disk r120 deilects slightly to balance the braking action.

To provide a downward force on the work clamp 26 with a minimum of -mass effect on the arm 42, as shown in FIGURE 4, there is a strip spring v68, which is similar to the springs 60 and 61 discussed previously. This tension spring 68 is secured to a long, substantially vertical cable 71 which is connected to the underside of the arm 42 so as to pull downwardly on this arm with relatively constant force regardlessof the horizontal position of the arm 42.

When the stitching of the pattern is completed, then the work clamp 26 is moved to a predetermined delivery position at which the arm 42 is raised against the force of the spring 68, thus releasing the completed work from engagement with the resilient compliant means 30 of the clamp 26. For raising the arm 42, lift means 76 (FIGS. 4 and 4a) are provided which engage the arm 42 in the delivery position. In this example the lift means 76 include an electrically controlled pneumatic cylinder 77 having a horizontal leg 81 on its piston rod. This leg element 81 enters a slot 86 in a downwardly projecting bracket 87 on the arm 42. Thus, the arm 42 can be quickly raised.

The fact that the horizontal leg element 81 is in the slot 86 prevents the arm 42 from continuing to rise when the lift means 76 reaches the end of its stroke, i.e., there is positive stopping and supporting of the work clamp 26 in its upper position, so that its operation can be accurately programmed. After the completed work has been removed a new piece of Work can be placed beneath the clamp 26 or, alternatively, the clamp 26 may be moved to another position at which it can be raised by another lift mechanism similar to the means 76 at the delivery station.

For accommodating the elevation of the arm 42 while minimizing the mass involved, the pivot 58 is mounted in a clevis 59, and the arm 42 is vertically slidable along the pivot 58 so that the cross link 56 remains horizontal. Also, the pivot connection '51 has an effective ball and socket arrangement to permit raising of the arm 42. The cross link 56 is held in horizontal position by an upper anda lower pair of saddle rollers 91. These rollers 91 are mounted in a yoke 97 which is pivotally supported at the end of a bracket 99 that is hinged at its other end to the frame so as to permit swinging of the bracket 99 in a horizontal plane to accommodate movement of the cross link 56.

By virtue of the fact that the cross link 56 is always horizontal and is parallel with and mid-way between the planes of the cams 46 and 47, there is clearance for the installation of cams which have large projecting lobes at any point on their periphery, if desired, Without conict with the cross link 56, thus minimizing the required length and mass of the arm 42 and associated drive link and levers 46 and 47.

In this system the needle 25 and arrester foot 34 are connected to a sewing machine 70 having certain conventional parts and many novel elements, as will be described further below. The power for driving the sewing machine 70 at high and at intermediate speeds is supplied from a main drive motor 72 connected by a timing belt 73 to a counter shaft 74 suitably journaled in bearings such as at 75. A main shaft 78 supported by bearings such as 79 parallels the counter shaft 74 and can be driven therefrom through a high-speed timing belt 80 or, alternatively, through an intermediate-speed timing belt 82.

When a high-speed electrically actuated clutch 83 associated with a large sheave 84 is engaged, then the driving path extends through the belt 80 to a smaller sheave 85 on the main shaft 78 so as to produce rotation of the shaft 78 which provides 6,000 stitches per minute. Alternatively, when an intermediate-speed electrically-actuated clutch 88 associated with a large sheave 89 on the main shaft is engaged, then the driving path extends through a small sheave 90 on the counter shaft 74 and through the belt 82 to the larger sheave 89, so as to provide an intermediate stitching rate of 2,400 stitches per minute.

For providing a slow operating speed equivalent to 200 stitches per minute, called inching speed, both of the clutches 83 and 88 are disengaged, and power is supplied by a slow-speed drive motor 92. 'Ihis motor 92 has a speed-reducing gear drive 93 and is connected by a timing belt 94 to a sheave 95 attached to an electrically-actuated clutch 96 on the main shaft 78.

The relation of the main shaft 78 always bears a known speed rotationship with respect to the rotation of the cam shaft 50, and this known relationship can be changed as desired depending upon the pattern being stitched and the required number of stitches per inch. The main shaft is fastened through a coupling 98 to a speed-reduction gear mechanism 100 having a vertical output shaft 101 connected through a change-gear train 102 to a driven gear 103 on the cam shaft 50. To change the speed relationship between the rotation of the main shaft 78 and the cam shaft 50, the gears in the change-gear train 102 are manually changed.

The cams 46 and 47 are individually removably secured to the shaft 50 each at a xed angular orientation, for example, by mounting these cams on respective hubs which are keyed to the shaft and are locked thereto by set screws. The hub '104 of the upper cam 46 is above the cable sheaves 66, and the hub for the lower cam 47 is below them. These cam hubs and these sheaves 66 can all be removed from the upper end of the shaft 50` so as to change the cams 46 and 47 when it is desired to stitch a different pattern.

In order to drive the sewing machine 70 at a known relationship with respect to the cam shaft 50, a drive path is provided, as shown in FIGURE 3 from a sheave 106 on the main shaft 78 to a driven sheave 107 (FIGS. 3, 6, 12 and 13) on the main crank shaft 108 of the sewing machine 70. This drive path to the sewing machine includes a timing belt engaging a sheave 111 on the input shaft 112 of a drive disengage and needle raise and lock-up mechanism 113 (please see also FIGURE 20) having an output shaft 114 with a sheave 115 engaging a timing belt 116 for driving the sheave 107.

In order to control the operation of the system, a plurality of switches (FIG. 4) are mounted beneath a narrow platform 132 which is spaced a substantial distance above the upper cam 46. A switch control drum 134 is removably secured to the upper end of the cam shaft 50, and a plurality of actuators 136 are adjustably secured to the outer surface of the drum at various distances below the upper end of this drum. The switches 130 are also mounted at various distances below the platform 132 so that each individual switch arm 138 is at the same elevation as its respective actuator 136. These actuators are removably secured to the drum, for example by machine screws, enabling them to be set at different positions around the drum, as shown in FIGURE 4. Thus, these actuators operate the various drum switches 130 at predetermined times when the cams 46 and 47 have reached various angular positions in their travel for automatically producing the desired sequence of operations.

As shown in FIGURES 5, 6, 7 and 8, the sewing machine 70 includes a yframe 140 having a horizontal arm portion 142 with a sewing head 143. The main crank shaft 108 extends horizontally within the frame portion 142 and is secured to a iiywheel 144 (FIGURES 7 and 8) having a crank pin 145 driving a connecting rod 146. The lower end of this connecting rod is joined by a wrist pin 147 to a collar 148 which is rigidly attached to a needle bar 150 for reciprocating this needle bar up and down. The needle 25 is of standard form and is fastened in a socket in the needle bar 150 by conventional means, with the needle thread being fed thereto by the usual guides and adjustable tensioning device 151 (FIG. 8) and a thread take-up arm. The guides and thread take-up arm are omitted from the drawing -for clarity of illustration, because they are conventional. FIGURE 8 shows the needle bar 150 in its raised position, this bar being vertically guided by the head frame portion 152 and by a lower bushing. The thread take-up arm is conventional and is included in the sewing head 143, being driven up and down by the main crank shaft 108.

As mentioned previously, there is a conventional bobbin mechanism located beneath the work table 24 near the needle throat opening 36. This bobbin mechanism is of the rotary type having a horizontal axis of rotation and turning at a rate of two rotations for each rotation of the crank shaft 108. This conventional bobbin mechanism is driven from the shaft 108 as shown in FIGURE 5 by means of a set of bevel gears 154 and by a vertical drive shaft 155 within the frame 140.

In order to operate the arrester foot 34, there is an eccentric 156 (FIGURES 5 and l0) secured to the shaft 108 for moving a connecting rod 157 having a pivot connection 158 held by a clamp 159 on a rock arm 160. This rock arm is adjustably attached by a clamp 161 to one end of a horizontal rock shaft 162, and it is the other end of this shaft 162 which serves to drive the arrester foot 34 as will be explained. The adjustable means 161 enables 12 the length of stroke and the dynamic action of the arrester foot to be varied so as to produce the desired down dwell time of the foot 34 during each stitching cycle for arresting the work region R.

As shown in FIGURE 5, the rock shaft 162 is journaled in bearings 163 and 164. The bearing 163 is mounted in the wall of a housing which is attached to the frame 140 and has a removable cover 166 for preventing the throwing of lubricating oil. The other bearing 164 rests in an L-shaped pillow block 167 which is fastened to the sewing head 143 as by a screw 168. A second rock arrn 169 (FIGS. 7 and 8) is held by an adjustable clamp 170 on the end of the shaft 162, and a pivot 171 with a connecting link 172 transfers the reciprocating motion to a pin 173 which is mounted by a clamp 174 on the top end of an arrester foot drive rod 175. Thus, this drive rod 175 is reciprocated vertically through upper and lower slide bearing blocks 176 and 177. The bearing 176 is anchored to the lower end of the L-shaped pillow block 167, and the bearing 177 is fastened by a bracket 178 to the side of the head 143.

When the drive rod 175 moves down, as shown in FIG- URE 8, a stroke-adjusting collar 179 affixed to this rod presses down upon one end of a lever 180 which is mounted at its center by a pivot bolt 181 in the head frame portion 152, and so the other end of this lever 180 lifts against a collar 182 on an arrester foot bear 183. Both ends of the lever 180 are bifurcated and straddle the respective rods 175 and 183 to avoid eccentric loading on the rods 175 and 183. In this way the arrester foot bar 183 is lifted against the continuous downward thrust of spring means 184, shown as a compression coil spring surrounding the bar 183 above the lift collar 182 and seated beneath the top part 185 of the head frame portion 152.

When the drive rod 175 is moved upwardly as shown in FIGURE 7, then the spring means 184 serves to press the arrester foot 34 down firmly upon the region R of the work W as described above in connection with FIGURES 1 and 2 so as to arrest the motion of this local region.

As seen clearly in FIGURES 5, 6, 7 and 8, the arrester foot 34 includes an annular portion 190 surrounding an opening 191 (FIGURE 2) concentric with the center line of the needle. By virtue of its round configuration the arrester foot 34 accommodates the close proximity of the edge 32 of the work clamp 26 regardless of the instantaneous direction of movement of the clamp. Thus, the stitching path P can extend in any instantaneous direction through a full 360 with respect to the needle so as to be able to produce any desired stitching pattern in two coordinates.

A semi-cylindrical barre] 192 is integral with the annular foot 34 and extends up along beside and concentric with the needle 25. This barrel 192 has an upper lateral mounting portion 193 which is rigidly but detachably secured to the lower end of the arrester foot bar 183. For example, as shown, the mounting means 193 includes a socket for receiving the lower end of bar 183 which is held by a screw 194. The arrester foot bar 1183 is guided by a lower sleeve bearing 196 (FIG. 8) mounted in the lower frame portion 152 and an adjusting screw 195 serves to set the compression of the spring 184.

In order to adjust the timing between the reciprocation of the needle and the action of the arrester foot, there are adjustment means as shown in FIGURES 10 and 10A, accessible by removal of the cover plate 166. These adjustment means include a clamp 186 for securing the eccentric 156 to the shaft 108 and an index disc 187 fastened to the eccentric. An index dial 188 is attached to a mounting on the bevel gear 154 fixed to the shaft 108. The adjustment is made by loosening the clamp 186 so as to turn the eccentric 156, and the adjusted position is shown by an index line 189 on the disc 187 which is adjacent to the marks on the face of the dial 188.

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