BACKGROUND OF THE INVENTION FIELD OF THE INVENTION This invention relates to a method and apparatus for finishing the edges of a flat, sheet-like work product. More particularly, the invention relates to a system for sewing the edges of sheet material such as wash cloths, towels, napkins and other textile goods, by forming an over edge stitch around the perimeter edge of the product.

DESCRIPTION OF THE RELATED ART

In the production of flat textile goods, such as wash cloths, napkins and towels, it is desirable that the products be formed with edges that are not likely to fray or otherwise deteriorate with use, and so that the edges remain attractive during use. Some products are folded at their edges to form hems and the hems are sewn closed to hide the cut or ragged edge of the product, however, the edges of some products can be finished as by simultaneously trimming the edge and forming overedge stitches about the newly trimmed edge. This latter treatment is satisfactory for some wash cloths and napkins.

In the past, when the edges of flat textile goods were to be finished with an overedge stitch, the sewing machine operator would feed and guide the edges of the work product to the needle in the sewing machine. This requires the operator to turn the product when the needle of the sewing machine approaches a corner of the product, therefore requiring relatively high operator skill and concentration for high quantity production.

While some automated equipment has been developed for guiding edges of flat textile products to sewing machines for the purpose of finishing the edges of the products, the prior art guiding devices known to the inventor do not successfully control the flat work product so that the product can be turned when the sewing needle reaches the corner of the product and so that the sewing function can continue automatically to sew the next adjacent edge of the product. This is particularly so if the product should not be formed with right angle corners and straight edges.

SUMMARY OF THE INVENTION

Briefly described, the present invention comprises an edge finishing system adapted for finishing the edges of flat products, such as textile products, including wash cloths, napkins, towels and other flat goods, whereby the work product is automatically aligned with one of its edges positioned at a finisher such as a sewing machine, the product then is advanced so that its edges are finished by the sewing machine. The product is automatically turned as the corner of the product approaches the needle of the sewing machine so that the finishing process continues around the corner of the product and then commences along the next adjacent edge of the product.

The invention is disclosed as utilizing an overedge sewing machine with a cutter so that the edge of a wash cloth or other textile work product can be trimmed by the cutter as the overedge stitch is formed by the needles of the sewing machine. Obviously, other edge finishing apparatus can be utilized and other work products can be finished by the edge finishing apparatus.

The control mechanism used to form and orient the work product comprises a cutter for cutting segments from a continuous supply of the goods that form the work product, and a detection and control system whereby an edge of the work product is advanced along a path through the finishing apparatus, the work product is turned when a corner approaches the finishing apparatus and the next adjacent edge of the work product is advanced along the path through the finishing apparatus. The system operates so that it will properly finish the edges of nonuniform work products, such as wash cloths and napkins that are formed with non- rectilinear edges and with corners that are not formed at right angles.

Photocells or other sensing devices are used to detect the presence of the perimeter edges of the work product as those edges approach the sewing station so as to begin the turning of the work product about a predetermined axis located at a known distance from the sewing station so as to form a radius about the corner of the work product.

Thus, it is an object of this invention to provide an automated edge finishing systemwhich functions expediently and efficiently to finish the edges of flat work products such as textile goods.

Another object of this invention is to provide an improved control system for controlling the movement of

flat textile goods at a sewing machine so that the goods can be manipulated during the sewing function so that the edges of the goods are properly finished.

Another object of this invention is to provide an automated control system which can be used in conjunction with an edge finishing device, such as a sewing machine, whereby a flat work product, such as flat textile goods, can be maneuvered so as to guide the edges of the work product to the needle of the sewing machine and the sewing machine can thereby finish the edges of the work product.

Other objects, features and advantages of the present invention will become apparent upon reading the following specification, when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective illustration of the edge finishing system.

Fig. 2 is a side elevational view of the transport plate, its cylinder, motor and travel head.

Figs. 3-9- are schematic plan views of a rectangular work product as it is manipulated adjacent the sewing station, showing how the work product is moved so that its edges move through the sewing station and then how the work product is turned as the next adjacent edge approaches the sewing station.

Fig. 10 is a plan view of a non-rectangular work product as it is manipulated adjacent the sewing station.

DETAILED DESCRIPTION

Referring now in more detail to the drawings, in which like numerals indicate like parts throughout the several

views. Fig. 1 illustrates edge finisher 10 that includes a substantially flat work table 11, sewing head 12, and work product control system 14. Cutting mechanism 15 and the feed system 16 move the work sheet material toward the edge finisher 10.

Feed system 16 supports a reel 18 of a continuous supply of the sheet material 19, such as terry cloth. The free end of the sheet material from the reel is moved through a conventional feed control 20 to the cutting mechanism 15. The cutting mechanism 15 includes a cutting blade 22 that is pivoted at one end and reciprocated by cylinder 24 so as to engage with a scissors-like action a cooperative cutting edge (not shown) located beneath the path of movement of the sheet material 19. If the sheet material is terry cloth, it is common that blank spaces 23 are formed across the material where the plush material is absent. This blank space is where the cutting blade 22 usually cuts across the sheet material. Suitable detecting apparatus (not shown) can be used to detect the blank spaces 23 in the terry cloth and to straighten those blank places, if necessary. The detecting and straightening apparatus can be of the type disclosed in U.S. Patent 4,595,133.

Once a segment 25 of the sheet material has been cut from the free end of the reel 18, the segment or "work product" can be moved to sewing head 12 for finishing of the perimeter edges of the segment. Edge finisher 10 includes a transport plate 28 that moves downwardly into flat engagement with segment 25. The facing surface of transport plate 28 includes a soft surface (not shown) that engages the upper surface of segment 25 so that a relatively firm gripping force is applied by the transport

plate to the segment. On the lower side of the segment 15 the flat work table is relatively smooth and offers little resistance to sliding movement of the segment 25. This enables the transport plate to move downwardly into engagement with the segment 25 and then move laterally across the work table 11 in "X" and "Y" directions and therefore transport the segment about the work table.

As illustrated in Figs. 1 and 2, work product control system 14 includes a travel head 29 mounted on transverse travel screw 30, with the ends of travel screw 30 being mounted in bearings 31 and 32. Reversible motor 34 is mounted to bearing 31 and functions to rotate travel screw 30. The motor 34 and its bearing 31 are mounted to perimeter travel block 35, whereas at the other end of travel screw 30 bearing 32 is mounted to perimeter travel block 36. Travel blocks 35 and 36 are mounted on perimeter travel screws 38 and 39. The travel screws 38 and 39 are mounted on end bearings 40, 41, and 42, 43, respectively. Reversible motors 45 and 46 engage travel screws 38 and 39, respectively, so as to impart rotary motion to the travel screws. Suitable mounting posts 48-51 support the work product control system 14 from the upper surface of the work table 11, so that the elements of the work product control system 14 are suspended above the work table. As illustrated in Fig. 2, expandable cylinder 55 extends between travel head 29 and transport plate 28. When cylinder 55 is contracted, transport plate 28 is lifted upwardly away from the work table 11 so as to separate the transport plate 28 from the work product 25, and when the cylinder 55 is extended, the transport plate 28 moves toward the work table 11 and toward the work product 25 so as to frictionally engage the work product.

Electric motor 57 is mounted to the lower portion of travel head 29 and its beveled sprocket 58 engages bevelled ring gear 59 which is mounted about cylinder 55. Cylinder 55 is rotatably mounted to travel head 29 so that the cylinder 55 and its transport plate 28 can rotate about a vertical axis.

A pair of sensing devices, such as photocells 61 and 62, are located adjacent sewing head 12. The photocells 61 and 62 are illustrated as being recessed in the surface of the work table 11; however, the photocells can be suspended over the work table, if desired. The photocells 61 and 62 are located adjacent the sewing needle 64 of the sewing head 12, with the pointed end 65 of the needle 64 and the associated presser foot, feed dogs, etc. comprising the sewing station 65 of the system. The sewing path 67 extends from right to left through the sewing station 65. Photocell 61 is positioned in the sewing path 67 and photocell 62 is positioned out of the sewing path and closer to the sewing station 65 than photocell 61.

OPERATION When the edge finishing system is placed in operation, the feed system 16 (Fig. 1) feeds out the free end of the supply of the terry cloth or other sheet material 19, and cutting mechanism 15 cuts across the free end of the sheet material so as to separate a segment 25 from reel 18. A computer control system (not shown) operates to rotate travel screws 30, 38 and 39 so as to bring the transport plate 28 over the cut segment 25 with the transport plate raised above the work table 11. When the transport plate 28 has become positioned over the segment 25 (Fig. 2) ,

cylinder 55 lowers the transport plate down into engagement with the segment 25.

As illustrated in Fig. 3 of the drawings, the transport plate 28 moves the cut segment 25 toward sewing station 65. The direction of movement is indicated by arrow 66; however, the direction of movement of the transport plate 28 and segment 25 can vary as may be necessary.

When the first edge 68 of the segment 25 moves beneath the needle 64 of the sewing head and through the sewing station 65, the first edge of the segment will also cover photocell 61. When photocell 61 senses the leading edge 68 of the segment 25, the movement of the segment 25 in the direction as indicated by arrow 66 terminates. In the meantime, if the segment 25 is a perfect rectangle, the other edges 69, 70 and 71 of the segment 25 will be formed at right angles with respect to each other about the work product, as illustrated.

Once the photocell 61 has been covered by the segment 25, the work product control system 14 will operate to move the transport plate 28 and segment 25 to the left (Fig. 4) as shown by arrow 72, so that the first edge 68 of the segment is moved along a sewing path 67 and through the sewing station 65 and is progressively trimmed and sewn by the sewing head 12, with the needle 64 of the sewing head 12 being illustrated in Figs. 3-10. The sewing head 12 is an overedge stitching machine and an overedge stitch 74 is progressively formed about the edge portion of the segment 25. When the segment 25 uncovers second photocell 62, this is an indication that the next adjacent edge 69 is approaching the sewing station 65 and the segment 25 must

be turned so that the sewing needle 64 will not sew off the segment. In response to the photocell 62 detecting the adjacent edge 69, the work product control system 14 begins to rotate the work product 25 about an axis of rotation 75. The axis of rotation 75 is located at a distance Y from the first edge 68 which is equal to the distance Z from the axis of rotation 75 to the second edge 69.

In response to the detection of the second oncoming edge 69 by the photocell 62, transport plate 28 will rotate about the axis of rotation 75. This causes the entire segment 25 to rotate counterclockwise about axis 75, as illustrated by the arrows 76 and 77 of Fig. 5. During the rotation the right angle corner 79 will be trimmed off of the work product as the trimming and sewing function continues to be performed by the sewing head.

When the turning function has reoriented the segment 28 as illustrated in Fig. 6 so that its second edge 69 is now approximately parallel to the sewing path 67 of the sewing head 12, the second edge 69 covers first photocell 61. When photocell 61 is covered at the end of the turning function, the control system terminates the rotational movement of the transport plate 38 about the axis of rotation 75, and then the right to left movement of the transport plate 28 is resumed as indicated by arrow 80 (Fig. 6) . This causes the second edge 69 of the segment 25 to move along the sewing path 67 through the sewing station 65 where the edge 69 is finished as by trimming and overedging. The right to left movement as indicated in Fig. 6 continues as shown in Fig. 7 until the second photocell 62 is again uncovered, whereupon the segment 25 is again rotated, as illustrated in Fig. 8. Again, the transport plate 28 is rotated about the axis of rotation

75 until the third edge 70 covers first photocell 61, whereupon the rotational movement imparted to the segment 25 by the transport plate 28 is terminated and linear movement resumes. This action is repeated until all of the edges 68-71 have been finished. As shown in Fig. 9, the segment 25 will have been rotated a full 360 degrees so that the unfinished portion of the first edge 68 can be finished at the end of the finishing operation.

An exhaust port 85 is formed in the work table 11 and is ducted to a vacuum chamber (not shown) . This causes the waste material 86 trimmed from the segment 25 to be progressively disposed of and taken away from the vicinity of the work table 11.

When the segment 25 has been finished by trimming and overedging as illustrated in Fig. 9, or by other finishing procedures, the segment is moved by the transport plate 28 and the work product control system 14 to a gap 88 (Fig. 1) in the work table where the segment is permitted to fall to a conveyor or stacker. Obviously, other retrieving and stacking devices can be used, if desired.

The X and Y right angle movements of the transport plate 28 as well as the rotational movement of the transport plate about the axis of rotation 75 are all controlled by the work product control system 14. In the embodiment illustrated herein, the work product control system comprises travel screws and other conventional motors, bearings and supports that function to move the transport plate in the X and Y directions. The motor 68 mounted to travel head 29 functions to rotate transport plate 28, by rotating the cylinder 55 with respect to the travel head 29.

While gravity tends to maintain transport plate 28 and travel head 29 in the upright attitude as illustrated in Fig. 1, guide bars (not shown) can extend through travel head 29 from perimeter travel blocks 35 and 36, if desired, to stabilize the transport plate. Moreover, the work product control system can comprise structural movement apparatus other than the travel screw system disclosed herein, as may be desired for varying conditions.

The software for the computer control system will include X and Y coordinates so that the positions of the transport plate 28, the axis of rotation 75 and the sewing station 65 will be known in the program. The coordinates for the axis of rotation 75 can be changed, and the coordinates for the transport plate 29 will be progressively changed as the transport plate is moved about the work table 11.

While the invention has been described as functioning to finish the edges of a rectangular work product, work products having corners that are not formed as right angles also can be accommodated by the invention. For example. Fig. 10 discloses a triangular shaped work product which can be handled by the system. Likewise, should the work product be non-symmetrical, the system will function to properly finish its edges. Further, if non-rectilinear edges are present on the work product, the work product control system continually adjusts the work product as it is being finished so as to follow the non-linear edges of the work product.

While the invention has been disclosed as finishing the edges of terry cloth material, it will be understood that the edges of other types of work products can be finished by the system, including other types of textile

goods as well as plastics, metals, and various other non- textile products. Also, while an overedge sewing machine has been disclosed as the implement that finishes the edges of the work product, other types of edge finishing apparatus can be employed in the system as may be desired. It will be understood that the foregoing relates only to a preferred embodiment of the present invention, and that numerous changes and modifications may be made therein without departing from the spirit and scope of the invention as set forth in the following claims.