Kitchener, Charles J. (Beverly, MA)
Rumball, Paul G. (Beverly, MA)

05/107022

03/27/1973

01/18/1971

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USM Corporation (Boston, MA)

112/309

271/1, 112/47, 112/470.090

D05B33/00; D05B35/10; D05B35/00; D05B27/14

112/2,121.11,121.12,121.15,204,205,47,162,203,DIG.2 271/1,51,52

3337212	Work guidance mechanisms	August 1967	Barker et al.
3589320	POCKET BLANK SEWING MACHINE	June 1971	Beazley
3598070	DRAG-STEERING WALKING-NEEDLE MACHINE	August 1971	Rosenberg

Boler, James R.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is

1. A machine for progressively operating on the margin of a flexible work piece having curved and/or straight peripheral portions, comprising an operating tool, a work support, an edge gage on the support ahead of the tool, feed means for rectilinearly moving the work piece on the support past the gage and to and through the operating zone to the tool, work guidance mechanism responsive to the position of an edge of the work ahead of the tool for urging the work edge toward progressive contact with the gage, and a work spreader plate movable toward and from parallel operative relation to the work support to aid said guidance mechanism in progressively presenting the work edge to the tool with the work outspread.

2. In combination with an overedging machine having stitch forming instrumentalities including a needle and a folder, a flat bed for slidably supporting a flexible work piece to be overedged, rectilinear feed mechanism adjacent to the needle, means including an edge gage ahead of the needle for progressively guiding an edge of the work piece to and through the operating zone of the needle and said folder, said guidance mechanism comprising a spreader plate mounted for relative movement heightwise of the bed for accommodating a work piece on the bed substantially in its own plane, a work turning member engageable with the work on the bed, and means automatically operable to rotate said member while engaging one locality of the work to slidably swing the work between the spreader plate and the table and tend to maintain an edge of the work to be overedged progressively in contact with the folder and contact or near contact with said edge gage.

3. A machine as set forth in claim 2 wherein the guidance mechanism includes a control circuit comprising a sensor responsive to movement of the work edgewise relative to the edge gage for operating said work turning member.

4. A machine as set forth in claim 5 wherein the work turning member is operatively connected to said control circuit for effecting heightwise movement of the member into and out of work engaging relation to a work piece on the bed at the limits of swinging movement of the piece.

5. A machine as set forth in claim 5 wherein said circuit includes a second sensor arranged to be actuated by said edgewise movement of the work for counting corners of the work to be overedged.

6. A machine as set forth in claim 7 wherein said second sensor is adapted to predeterminedly stop operation of the machine and elevate the spreader plate from the bed prior to said cessation of operation of the machine on the work whereby beginning and terminal overedging may overlap without interference from the plate.

7. A machine as set forth in claim 5 wherein said circuit includes a sensing means adjacent to the edge gage for controlling by air flow the pressure of edgewise engagement of the work with said gage.

8. A machine as set forth in claim 5 wherein said sensor includes a pair of fluidic elements respectively having graded orifices aligned for communication and interruption by the work edge to provide a range of sensitivity in accommodating work pieces having different degrees of perviousness.

9. In a machine having a tool for progressively operating on the margin of a flexible work piece having convex corner portions, a work support having an edge gage positioned thereon ahead of the tool, a work spreading plate smaller than and overlying the work support and movable heightwise thereof to accommodate reception of the work piece therebetween, means operative adjacent to the operating zone of the tool for rectilinearly feeding the margin through said zone, a work turning member cooperative with the work support and movable heightwise thereof, and corner sensing means responsive to relative movement of approach of the work edge with respect to said gage for angularly operating the turning member to urge a corner portion of the work piece to progressively pass through said zone while other portions of the work continue to be acted on by said rectilinear marginal feed means.

10. A machine as set forth in claim 9 wherein a control circuit includes a corner counting means responsive to operation of said corner sensing means a predetermined number of times for terminating operation of the machine.

11. A machine as set forth in claim 10 wherein said corner counting means is adapted to separate the work spreading plate and said work support heightwise in response to operation of the corner sensing means a predetermined number of times.

12. A machine as set forth in claim 11 wherein said control circuit is adapted to maintain said work turning member in work engaging relation after a predetermined number of corners are sensed by said corner sensing means whereby angular return of the member is effective to remove the work piece from said tool and edge gage.

BACKGROUND OF THE INVENTION

This invention pertains to automatic feeding of flexible sheet material with respect to a tool for operating thereon. Several earlier patents disclosing guidance technique and having the same assignee as the present application include:

U.s. pat. No. 3,080,836 -- Clemens et al.

U.s. pat No. 3,337,212 -- Barker et al.

U.s. pat. No. 3,034,781 -- Touchman.

The great variety of flexible materials, especially sheets of fabric and the like, presents problems due to the range of physical characteristics affecting their uniform treatment and movement by machinery. Guidance by mechanical as opposed to manual means has become highly important nevertheless as a preferred approach to obtaining more accurate results at lower cost and without the drudgery hitherto attendant to the physical handling of flexible work pieces. While the present invention is herein illustrated and described with respect to the performance of a peripheral sewing operation, specifically the overedging or serging of generally rectangular fabric work pieces such as face cloths, dish cloths or industrial wipe towels having corners of uniform curvature, it is to be recognized that the invention is not limited to the sewing machine field, but may well have application to other machinery, mainly those types wherein the flexible work, of whatever form, has a curved and/or straight edge to be progressively processed with minimal attention on the part of an operator.

SUMMARY OF THE INVENTION

In view of the foregoing it is a primary object of this invention to provide in combination with a machine for peripherally operating on flexible sheet material, for instance an overedge sewing machine having a rectilinear feed means, an improved automatic work moving means for facilitating operations on successive work pieces having straight and/or curved edges.

A further object is to provide an easily operable overedging machine capable of continuously and automatically processing straight edges and interconnecting curved portions of wipe towels, face cloths, and the like.

More specifically it is an object of this invention to provide an auxiliary control system of electropneumatic type for enabling a sewing machine to stitch the whole or a selected portion of a work margin including "corners" of predetermined curvature, an operator or other device merely presenting each work piece initially.

To these ends an illustrative overedge sewing machine of suitable character is fixedly mounted with its throat plate substantially horizontal and overlying conventional feed dog means. The throat plate defines a needle operating zone relatively to which work pieces are to be progressively guided. Preferably, therefore, a novel and substantially flat work supporting table, even with the throat plate and usually of less width than the work which may overhang, has a convexly arcuate edge disposed ahead of the needle operating zone and extending toward but spaced from an edge gage to aid edge guidance as hereinafter explained.

As herein shown, immediately ahead of the stitch forming means is an edge folding device, and still further ahead is an edge gage for guiding the edge of the work to the folder. In presenting a work piece initially to the stitch forming means and in engagement with the folder and edge gage, a plurality of sensors adjacent to the latter and preferably fluidic, are thereby actuated to control the operating cycle. Thus at each "corner" to be stitched air flow switching of a corner turning sensor signals for operation of a turning arm to swing the work, as the rectilinear work feeding means continues to operate, bodily about a center spaced from the needle axis. Another sensor counts the number of corners so turned in order to actuate accessory devices such as a thread cutter, and to elevate a work spreading plate from the work table to provide passageway for a final overlapping seam portion before terminating a cycle of operation.

A third sensor controls air flow directed against a side of the work piece to stabilize and yieldingly limit the pressure with which an edge of the flexible work shall bear against the edge gage.

Advantageously, each of the fluidic sensors may be provided with graded orifices, the larger pairs of orifices being closer to the edge gage, whereby appropriate functioning is attained on work pieces of different mesh or porosity.

BRIEF DESCRIPTIONS OF THE DRAWINGS

The foregoing and other features of the invention together with novel combinations of parts will now be more particularly described in connection with an illustrative embodiment and with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view, from the front, of work guidance means and accessories as provided for an overedging machine indicated by dash-lines in the background;

FIG. 2 is an end view, largely in vertical section, showing a work spreader plate, work guidance means, and other instrumentalities as seen in their inoperative or up positions relative to a work supporting table;

FIG. 3 is a view corresponding to FIG. 2 but illustrating the several parts lowered into operative work-engaging relation;

FIG. 4 is a section taken on the line IV--IV of FIG. 3 showing work guidance elements in relation to different positions of the work;

FIG. 5 is a view somewhat similar to FIG. 4 but showing stitching operation following corner trimming and counting; and

FIG. 6 is a schematic diagram of a fluidic control circuit which may be employed.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A machine 10 (FIG. 1), for instance an overedging machine such as a commercially available Merrow model M3DR, is fixedly mounted with its throat plate 12 (FIGS. 1, 4 and 5) disposed at a convenient horizontal position. The plate overlies rectilinear feeding feed dog mechanism 13 (not shown except in FIG. 5) for incrementally advancing a work piece W to the left as seen in FIGS. 4 and 5 and parallel to a straight stop cover 14. The plate 12 defines a needle operating zone Z adjacent to a stationary narrow folder 16 which may be of conventional form. Though not shown herein except in FIG. 5, the machine is also preferably provided with a trimming knife 17 for rounding angular corners, severing irregular marginal edges and threads ahead of the folder 16, a vacuum duct 18 (FIGS. 1 and 2) being arranged below the knife to dispose of trimmed off material.

In order to enable the machine 10 to continuously operate automatically along straight edges and interconnecting curved edge portions, such as the margins comprising the four corners C (one shown trimmed and sewn in FIG. 5) commonly found in wipe cloths or other rectangular articles having "corners" of predetermined radius, a stationary work table 20 is secured evenly with the plate 12 and desirably is formed with a convex, substantially circular advance outer edge 22 which extends inwardly toward an edge gage 24 fixed on the table 20. The latter is supported on a frame including an overhanging U-shaped plate 26 (FIGS. 1-3) from which the several accessory devices hereinafter to be described are suspended for relative vertical operating movement with respect to the table 20.

A work spreading top plate 30, which may be of low-friction transparent plastic, preferably has a convex edge 32 of contour similar to that of the edge 22 though of smaller radius. The plate 30 is yieldingly spaced parallel to the table by means of a pair of leaf springs 34, 36 interconnecting upright brackets 38, 40, the former of which is connected to the plate 30 and the latter of which is secured to the U-shaped plate 26. The arrangement is such that the springs 34, 36 normally lift the plate 30 sufficiently, as shown in FIG. 2, to allow easy admission and removal of a work piece W to be processed, the upper position of the plate 30 being adjustably determined by a stop screw 42 (FIGS. 2 and 3) threaded through a bracket 44 for engagement with the spring 34. The lower position of the plate 30, only slightly above the upper face of the work piece, is adjustable for different thicknesses of fabric or the like by means of a stop screw 46 engageable with the underside of the spring 36, the screw being threaded through a bracket 38 secured to the bracket 40.

For shifting the plate 30 downwardly to its operative or work spreading position, fluid pressure is admitted to a cylinder 50 supported from the frame plate 26 and carrying a spring return piston rod 52. A threadedly adjustable head 54 on the rod 52 is arranged to engage and downwardly move the bracket 38 from its upper position shown in FIG. 2 to its lower position shown in FIG. 3 upon commencing the sewing operation in response to presentation of a work piece to actuate the control circuit.

For work guidance purposes the spreader plate 30 has a cutaway portion 55 (FIGS. 1, 2 and 4) for accommodating three pairs of fluidic sensors designated 56, 58; 60 and 62; and 64, 66 comprising the control circuit shown in FIG. 6. In order to be responsive and properly sensitive to fabric of different mesh or porosity sensors 56, 58 are respectively provided with small, medium, and large size orifices generally designated 68 (FIG. 5), a pair of like sizes being in communication unless fluid flow therebetween is interrupted as by the presence of a work piece W in edge contact with the gage 22 or approaching such contact. The orifices 68 are arranged so that they are larger in the communicating pairs nearer the gage 24. The arrangement is such that, as an edge of the work is folded and fed leftward relative to the needle operating zone Z, if a trailing portion of the work edge is so contoured as to provide no interruption of flow between the sensors 56, 58, as suggested by the dashed edge position shown in FIG. 5, corner turning mechanism including an L-shaped work-engaging finger 70 (FIGS. 1-4) is automatically actuated as later described to swing the work counterclockwise as viewed in FIG. 4 and thereby reposition it so as to re-interrupt the flow and maintain substantially uniform overedging without interruption or necessary slow down.

The finger 70 preferably carries a tubular rubber work-engaging tip 72 and, in response to the sensors 56, 58, is automatically movable both heightwise and in arcuate swinging movement for slidably clamping a work piece portion against the table 20. For this purpose one end of the finger 70 is formed as a collar 74 (FIGS. 2 and 3) secured to the lower end of a shaft 76. The latter is mounted for rotation about its vertical axis and extends through alined bores formed on horizontal arms of a U-shaped bracket 78. The radius of the corner to be negotiated determines the location of the axis of the shaft 76, i.e. the pivot point of the tip 72, in conjunction with its speed of rotation. For a minimum corner radius of about 2 inch, the axis is located empirically 1 3/4 inch out from and in line with the front edge of the mentioned trimming knife 17, for instance. The bracket 78 is secured to a later mentioned bracket 80 itself rigidly supported by an S-shaped support 81 secured to the plate 26. Rotation of the shaft 76 is effected by an air cylinder 82 (FIGS. 1 and 4) the horizontal piston rod 84 of which shifts a rack 85 for rotating a pinion 86 secured on the shaft 76. A compression spring 88 (FIGS. 2 and 3) confined between a collar 90 on the shaft 76 and a shoulder of a bracket 78 serves yieldingly to urge the finger tip 72 downwardly into work-engagement as shown in FIG. 3 while the rack and pinion remain in mesh. For overcoming the spring 88 and elevating the finger 70, a swivel support 92 from which the shaft 76 is suspended by means of a collar 94 is urged upwardly by a tension spring 96 interconnecting the support 92 and an air cylinder 98 mounted on the bracket 80. The spring 96, in turn, is overcome at proper times by operation of fluid pressure admitted to the cylinder 98 to cause its piston rod 100, threadedly connected to the support 92, to project the shaft 76 downwardly. Thus, in response to non-interruption of the flow between sensors 56, 58 by the work, the tip 72 is at once lowered to engage the work approximately in the full line position indicated in FIG. 4 and then be swung counterclockwise about the axis of the shaft 76 (which preferably is slightly ahead of the needle operating zone Z) to about the dashed line position shown. Now, flow being cut off between the sensors 56, 58, the tip 72 is disengaged from the work and separated heightwise for ineffectual return rotation. The edge of the work piece W about to be overedged has accordingly been swung to maintain operative relation with the folder 16 and again abuts the edge gage 24 as shown in FIG. 5.

It is to be noted that other forces are also simultaneously tending to aid in restoring the work edge to be overedged into contact with the gage 24. As the feed dog repeatedly exerts feeding movements tending also to swing the work counterclockwise, a portion of the work overhangs the convex outer edge 22 of the table 20 and tends to slide circumferentially thereby shifting the horizontally supported portion of the work toward the edge gage independently of any urging of the swing finger tip 72. The width of the table 20 should be appropriate for the nature of the work and not provide excessive drag tending to misalign the work with the gage 24.

The sensors 60, 62 are provided for counting the desired number of "corners," i.e. occasions when edge curvature of the work is sufficient to require work swinging by means of the finger 70 in response to non-interruption of the sensors 56, 58. In overedging the usual rectangular work towel, for example, when the fourth corner C has been negotiated, the control circuitry responsive to the sensors 60, 62 counting the four corners will stop the machine 10 and, in this case, automatically actuates a chain stitch cutter 102 (FIGS. 1-4) controlled by fluid pressure admitted to a cylinder 104. This cylinder is supported from a bracket 106 depending from the plate 26 and has a piston rod 108 operatively connected to the cutter 104. The corner counting circuitry may be adjusted to actuate the cutter and stop the machine at any selected number of corners turned.

The sensors 60, 62 also serve another important purpose. When the last corner has been overedged, they act automatically to exhaust the cylinder 50 thereby allowing the spreader plate 30 to be spring-lifted sufficiently to enable the additional thickness of the seam of the initial overedging to pass thereunder. The full perimeter of the work piece W may then be processed and the overedging overlapped adjacent to the final corner as desired. Also, the present corner count being completed, the turning tip 72 remains down engaging the workpiece as the finger 70 is rotatively retracted to move the material about to engage the trimming knife and presser foot away from the sewing area.

Because the work W may at times be thin or flimsy, the forces mentioned above tending to force the work against the gage 24 may cause the work edge to buckle, jam or unduly furl thereby preventing proper edge alignment functioning of the gage. Also, the higher the humidity of the air, the greater the tendency of fabric to be flabby and to fold. The sensors, 64, 66 are disposed to prevent such misalignment and operate as will next be described. The sensors 64, 66 are disposed immediately adjacent to the edge gage 24 in position to be interrupted just prior to work edge "crowding" of the gage. Accordingly at initial fluid flow cutoff between the smallest orifices 68 of the sensors 64, 66 as the work approaches the gage, a small checking effect in this approach is caused by directing air flow via nozzle 110 (FIGS. 1, 3 and 4) against the work and away from the edge gage 24. As the larger pair of orifices 68 of the sensors 64, 66 is interrupted further air checking is similarly obtained and the work edge is thus enabled gently to be maintained in proper gage contact. The signal from the sensors 64, 66 activates the air jet and is found to eliminate the buckling problem when operating in conditions up to 80 percent relative humidity and 90° temperature.

A sequence of principle operations of the machine will now be briefly described having reference in part to FIG. 6. A rectangular work towel W, for instance, is inserted on the table 20 under the plate 30 and with a starting portion of a first straight side in the needle operating zone Z. A presser foot 112 (FIG. 1) of the machine 10 and the spreader plate 30 are then lowered either manually or, in the illustrative machine, automatically following closure of a starting switch 114 (FIG. 6). Presentation of the work W with its straight trailing edge in contact (or near contact) with the gage 24 interrupts the fluidic sensors 56, 58 and 60, 62. The arrangement in the control and counting circuit shown preferably is such that Schmitt triggers 3-9 and 2-8 respectively associated therewith have their bias pressure so adjusted that they switch on when two air jets are interrupted by the work and switch off when only one is thus interrupted. A single thread or small opening between threads of the work will not trigger the switches. The work presentation also interrupts the sensor 64, 66 shifting its Schmitt trigger 1-7 and causing signals to be applied to valves V-7 and V-9. The valve V-7 supplies air flow to the nozzle 110 of the anti-edge folding means above described. Signals are applied to fluidic devices 4-10, 5-11 and 6-12 properly to shift each counter stage, and to a valve V-4 to supply air pressure to switch PS-1, to valve V-3 which lowers the presser foot 112, and to a clutch (not shown) controlling drive of the motor 10 and operated by a piston cylinder device 116 (FIG. 6). The actuation of the switch PS-1 is effective to draw suction via the duct 18.

With the machine 10 now operating, a valve V-1 is shifted to pressurize the cylinder 50 and lower the plate 30. As the operating locality along the edge of the work W approaches the first corner C the sensors will be in communication, respectively, i.e. uninterrupted. A signal is sent to valve V-6 pressurizing cylinder 98 to lower the finger tip 72 into work engagement at the position shown in FIG. 1, and a signal is sent to a valve V-5 pressurizing the cylinder 82 to cause the finger 70 to rotate counterclockwise thereby turning the work piece W so that a corner C is overedged and registering the first corner in the counting means. The earlier mentioned steps are now repeated for further rectilinear overedging. The machine 10 at no time necessarily slows or stops as the corner is formed and sewn. As the next straight edge portion of the work piece interrupts the sensors 56, 58 and 60, 62 and contacts the edge gage 24 the signal is removed from the valves V-5, V-6, respectively, and the turning tip 72 is lifted from the work and returned angularly to its starting position in readiness for the next work corner. The machine does not stop but continues sewing the next straight edge.

If the work edge tends to swing hard against the edge gage 24 as the straight or nearly straight edge is to be processed, air flow between the sensors 64, 66 will be interrupted to check unwanted edge folding action by counter acting air jet as above described, the jet tending to urge the fabric from interrupting relation with the sensor 64, 66. This checking may thus turn on and off as the work margin is progressively guided relative to the gage 24 and to the needle operating zone Z.

The second and third corners C having also been registered in the fluidic counting means, as the fourth corner C approaches the needle operating zone Z, a signal from the fluidic device 18 (FIG. 6) causes the valve V-1 to shift and exhausts the cylinder 50 thus allowing raising of the spreader plate 30 by the return spring of that cylinder and accommodating the thicker previously rolled and sewn work edge. The corner turning mechanism operates as previously described, and the fluidic device 13-19 (FIG. 6) signals devices 15, 16 and 21 (a time delay determining how much longer the machine 10 is to operate) whereby the valve V-5 is shifted causing the turning tip 72, while still engaging the work, to return clockwise from its dashed to solid line positions shown in FIG. 4. Hence the work W is steered away from and clear of the edge gage 24, the presser foot 110, and the trimming knife 17, and on expiration of the time delay, signals via the devices 16 and 22 call for shifting of the valve V-6 whereby the returned tip 72 is lifted from the work. The speed of angular retraction of the tip 72 taken with the degree of the time delay determine the accuracy of the final stitching in blending with the initial overedging. A signal is applied to fluidic device 20 whereupon the valve V-4 shifts to remove air pressure from PS-1 stopping suction in the duct 18, from the clutch operating cylinder 116 to stop the machine 10, and from a valve V-3 to raise the pressure foot 112 by exhausting its operating cylinder 118 (FIG. 6). A signal to PV-1, initiated by the time delay associated with fluidic device 20 (FIG. 6), causes the valve V-2 to effect one operating cycle of the cutter 102 to sever the thread chain automatically and allow removal of the work from the machine. Actuation of a valve V-8 (FIG. 6) will cycle the thread cutter 102 when desired, and actuation of a valve V-10 is effective to operate the sewing machine 10 without benefit of its work guidance system.

By reason of its reliable automatic corner turning and work guidance as above described, a single operator may attend three machines of the illustrative type, for instance, thereby continuously accomplishing, at high linear feed speed, a high edge finishing output. Moreover the system described permits processing any selected number of work pieces sides, and no adjustment of the machine is required for operating on different sizes of work pieces.