Loader-unloader for automatic sewing apparatus
United States Patent 1 Conner, Jr.  
 [ Apr. 22, 1975 [75] inventor: William R. Conner, Jr.., Shelbyville.  
 Tenn.  
 [73] Assignee: Stahl-Urban Company, Brookhaven,  
 Miss.  
 [22] Filed: Dec. 7, 1973 211 App]. No.: 422.682  
 {52} US. Cl. Ill/121.29  
 [51] Int. Cl D0511 33/00 [58] Fieldofsearch 112/10, 121.11, 121.12. ll2/121.l5, 121.29  
 [56] References Cited UNITED STATES PATENTS 3,116,705 1/1964 Kosrow 112/1212) 3,382,825 5/1968 Cash 112/1212) X 3,769,924 11/1973 Rogers 112/1212) 3,793,968 2/1974 Bcazlc 112112129 Primary E.\&#39;aminerWerner H. Schroeder Attorney, Agent, or Firm-Koenig, Senniger, Powers and Leavitt 57 ABSTRACT A loader-unloader for automatic sewing apparatus or the like. the sewing apparatus comprising a sewing machine having a needle, 21 work holder for holding work to be sewn and means for moving the work holder and the work held thereby along the predetermined path relative to the needle so as to stitch the work along a predetermined stitching line, the loaderunloader comprising transfer means on which work to be sewn may be positioned for being transferred to the work holder, means for locating the work on the transfer means in a predetermined position, and means for moving the transfer means for transferring the work to be sewn to the work holder and for removing previously sewn work.  
 25 Claims, 9 Drawing Figures LOADER-UNLOADER FOR AUTOMATIC SEWING APPARATUS BACKGROUND OF THE INVENTION This invention relates to apparatus for loading work to be sewn (e.g.. piece of cloth) in automatic sewing apparatus or the like and for unloading previously completed (e.g.. sewn) work from sewing apparatus.  
  Garment manufacturing is a labor intensive industry and thus efforts are continuously being made to automate various operations so as to increase worker and machine productivity. Automatic sewing apparatus. such as described in my US Pat. No. 3.771.477 has been developed to speed production and cut costs. Heretofore, work was entirely manually loaded in and unloaded from automatic sewing apparatus. Not only was the loading and unloading of the work holder in and of itself time consuming, but of necessity these operations were done after the sewing of the work was completed. This resulted in appreciable delays between sewing cycles thus not making full use of the high speed sewing capabilities of the automatic sewing apparatus. Also, manual loading of the work holder resulted in some of the work being improperly positioned in the work holder and thus resulting in improperly sewn work.  
 SUMMARY OF THE INVENTION Among the several objects of this invention may be noted the provision of a loader-unloader for automatic sewing apparatus or the like which quickly and accurately loads work to be sewn in the sewing apparatus and simultaneously removes previously sewn work therefrom; the provision of such a loader-unloader in which work to be sewn may be manually placed on the loader while other work in the sewing apparatus is being sewn so that upon completion of the work being sewn. the new work may rapidly be loaded in and the completed work unloaded from the sewing apparatus reducing the time between sewing cycles of the sewing apparatus and thus increasing its productivity; the provision of such a loader-unloader which is safe to operate; the provision of such a loader-unloader which accurately places the work in the sewing apparatus in a predetermined sewing position so that the completed work is of greater uniformity and thus reduces wastage of cloth; the provision of such a loader-unloader for which it is easy to train an operator and which does not require high operator skill; and the provision of such a loader-unloader which is of relatively simple construction and which is reliable in operation. Other objects and features of this invention will be in part apparent and in part pointed out hereinafter.  
  Briefly, a loaderunloader of this invention is especially adapted for use with automatic sewing apparatus or the like. the automatic sewing apparatus comprising a sewing machine having a needle. a work holder for holding work to be sewn, and means for effecting relative movement of the work holder and the sewing machine so as to stitch the work along a predetermined stitching line. The loader-unloader of this invention comprises transfer means on which work to be sewn may be positioned for being transferred to the work holder, means for locating the work on the transfer means in a predetermined position, and means for moving the transfer means for transferring the work to be sewn to the work holder and for removing previously sewn work.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of automatic sewing apparatus and a loader-unloader of this invention, the sewing ap paratus having a work holder for holding work to be sewn and the unloader having a pair of tables or trays selectively movable inwardly toward the work holder when the work holder is in a home position adjacent a respective table or tray and then movable outwardly for simultaneously loading work to be sewn and for unloading previously sewn work;  
  FIG. 2 is a front elevational view of the sewing apparatus and loader-unloader of this invention illustrating an air conveyor for conveying away completed work once removed from the work holder;  
  FIG. 3 is an end elevational view of the sewing app-a ratus and loadenunloader;  
  FIG. 4 is an enlarged side elevational view of the work holder illustrating a clamping means in a clamped position (shown in solid lines) and a raised unclamped position (shown in phantom), and a table in its retracted or starting position;  
  FIGS. SA-SD diagramatically represent the sequence of operation of the loader-unloader for loading work to be sewn onto the work holder and for simultaneously removing previously sewn work from the work holder; and  
 FIG. 6 is a schematic of a pneumatic circuit.  
  Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, a loader-unloader of this invention, indicated in its entirety at I. is shown as operatively installed on automatic sewing apparatus generally indicated in its entirety at 3. Briefly. this sewing apparatus is a punch tape programmable sewing apparatus similar to apparatus disclosed in my US. Pat. No. 3.77l,477.  
  More particularly, the sewing apparatus includes a frame 5 supporting a power driven sewing machine 7 of a commercial type, with the sewing machine having a needle 9, and a work holder or carriage. generally indicated at 11, for holding work W] to be sewn for movement along a predetermined path relative to the needle so as to stitch the work along a predetermined stitching line. The sewing apparatus further includes a drive for moving the work holder in incremental steps along an X-axis and a Y-axis in accordance with a predetermined program, comprising an an X-drive 13 for moving the work holder lengthwise along frame 5 parallel to the X-axis and a Y-drive 15 for moving the work holder transversely of the frame parallel to the Y-axis.  
  The loader-unloader I includes transfer means generally indicated at 17 on which work W] to be sewn may be positioned for being transferred to work holder 11. This transfer means comprises a pair of transfer members or tables 191: and [9b (the latter being shown in phantom in FIG. I) for supporting work W1 to be sewn in a predetermined position relative thereto. Locating pins 21 are provided for each table l9a, 19b. these pins being movable upwardly and downwardly relative to the table between a raised position (see FIGS. 4 and 5A) in which they project up above the upper surface of the table and constitute a stop for work WI thereby to position the work in its predetermined position relative to the table and a lowered retracted position (see FIGS. SB-SD), clear of the table permitting movement of the table for purposes as will appear. It will be understood that these locating pins 2i constitute means for locating the work to be sewn in a desired position on tables 19a. 19b. Clamps 23 are pro vided on each table 190. and 19b for holding work on the table in its above mentioned predetermined position. These clamps are automatically operable to engage the work W1 and to hold it in its predetermined position until the work is in position for being deposited in work holder II, and then automatically release the work for transfer to the work holder. As generally indicated at 25, means is provided for moving the transfer means (i.e., tables 19a, l9b) from a starting or retracted position. as shown in FIG. 5A, to a load position (shown in FIG. SB) for transferring work Wl to be sewn from the table to the work holder and for remov ing previously sewn work W2 from the work holder (see FIG. 5D), and then returning to its starting position.  
  More specifically. X-drive l3 and Y drive of sew ing apparatus 3 comprise an X stepping motor and a Y stepping motor respectively indicated at 27 and 29; these stepping motors are discretely operable in response to signals generated by a punch tape programmer 3] so as to step the X and Y stepping motors in such fashion as to move work holder ll along the above mentioned predetermined path relative to needle 9 so the needle may stitch work along a predetermined stitching line. The work holder is movable generally laterally relative to the sewing machine from a first home position H] (as shown in solid lines in FIG. I) in which the work WI held by the work holder is clear of needle 9 and in which work may be loaded on and unloaded from the work holder by means of the loader-unloader I to an operating position (not shown) in which the work may be stitched by needle 9 along the above-mentioned predetermined stitching line. The work holder is further movable generally laterally with respect to the sewing machine to a second home position H2 (shown in phantom in FIG. I) on the opposite side of the sewing machine from position HI. Transfer means I7 is positioned relative to sewing machine 7 for transferring work W] to be sewn to the work holder, and for removing previously sewn work W2 from the work holder when the work holder is in either its first or second home position. As best shown in FIG. 4, work holder II includes a sewing platform 33 on which work WI is held for being stitched by a needle 9 and a movable clampingjaw 35 movable between a lowered clamping or closed position and a raised retracted or open position (as shown in phantom) by means of air cylinders 37. With the clamping jaw in its lowered clamping position, work is securely held in position on sewing platform 33 in a predetermined sewing position for being stitched by needle 9, and with the clamping jaw in its raised retracted position, previously sewn work W2 may be removed from the sewing platform and work W] to be sewn may be deposited thereon by means of transfer means 17 in the above-mentioned sewing position. Clamp jaw 35 has a gripper pad 39 on its lowered surface for engaging work to be sewn and for holding it in its stated sewing position.  
  Loader-unloader I further comprises a subframe 41 carrying transfer means 17, this subframe being adjustably movable laterally relative to frame 5 for positioning tables 19a, 19b generally in front of the work holder 1 I when the work holder is in its first and second home positions H1 and H2. The loader-unloader further comprises an air conveyor, generally indicated at 43, for conveying away previously sewn work unloaded from the work holder. It will be understood that conveyor 43 may include a stacker for stacking sewn work after removal from the sewing apparatus.  
  Means 25 for moving tables 19a, 19b for transferring work W] to be sewn to the work holder and for removing previously sewn work W2 from the work holder is shown to comprise a horizontal guide or slide rod 45 extending generally parallel to the direction of movement oftables 19a, and 19b as they move between their retracted and load positions. A slide bearing 47 is slidably received on guide bar for sliding movement axially therealong. A bar 49 is secured to and movable with slide bearing 47, with one end of the bar being supported by a roller 5i rolling on a frame member 53 of frame 41. A three bar linkage, generally indicated at 55, is connected to bar 49 for effecting movement of this bar along slide rod 45, this three bar linkage including a pivot link 57 pivotally connected to bar 49 and a crank 59 pivoted on frame member 53 and pivotally connected to pivot link 57. An air cylinder 6! constituting fluid power operated means is interposed between crank 59 and frame 41 whereby extension and retraction of the piston rod of the air cylinder effects axial sliding movement of the slide bearing 47 and bar 49 along slide rod 45. A respective table I9a or 1911 is pivotally supported on bar 49 by means of angle 62 pivotally connected to bar 49 by means of pivot arms 63. The table is biased upwardly by means of a compression coil spring 65 and a stop 67 carried by slide bearing 47 prevents movement of the table beyond a raised position in which the table is disposed at a slight angle (e.g., 5) from the horizontal with its leading edge sloping downwardly for receiving work W1 to be sewn on its upper surface. The spring permits downward movement of the table from its raised loading position (e.g., the inclination of the table being approximately 8 as shown in FIG. 50).  
  Locating stops or pins 21 are movable vertically in slots 70 in tables 19a, 19b by means of an air cylinder 71 carried by frame 41. More particularly, pins 21 are movable by the air cylinder 7] between a raised locating position (see FIG. 5A) in which the pins project upwardly through slots 70 in the table thereby to locate work W1 to be sewn in its predetermined position on the table and for being gripped by clamps 23 and a lowered retracted position (see FIGS. 5B-5D) clear of the table thereby to permit movement of the table from its retracted position to its load position and to permit removal of work WI from the table. Pins 2] and air cylinder 71 are adjustably movable relative to frame 41 so that the position of the pins relative to tables 19a, 19b may be varied to accommodate work of different sizes and shapes. As indicated at 73 (see FIGS. 4 and SA-D), a pad is provided on the lower front edge of each table 19a. 19b for engagement with previously sewn work W2 supported on sewing platform 33 to remove it from the sewing platform as the table I90, I91) returns to its starting position (see FIG. 5D). An air switch pushbutton 75 (see FIG. 1) is provided on each table 19a. 19b, this button being actuable by the operator to initiate a sequence of operation to automatically load a piece of cloth (i.e.. work W1) onto the upper surface ofa respective table 19a. 19b to be sewn. to deposit this work to be sewn on sewing platform 33 of work holder 11 in a predetermined sewing position. and to remove previously sewn work from the work holder.  
  As shown in FIG. 4. clamps 23 each comprise a miniature air cylinder 77 having a piston rod 79 with the rear end of the cylinder pivotally secured to a mounting fixture 81. A crank 83 is pivotally connected to the pis ton rod and to the mounting fixture and a downturned clamping foot 85 is carried on the outer end of the piston rod for engagement with work W] on the table. Upon actuation of air cylinder 77 to extend its piston rod 79, clamping foot 85 is lifted by crank 83 from a down retracted or unclamped position (see FIG. 4) in which it is clear of the work and is moved up over the work and lowered to a clamped position in engagement with the work thereby to hold it in position on the table. The piston rod is spring loaded to return to its retracted position upon the release of air from the air cylinder. Thus. to unclamp the work. air cylinder 77 is vented and the clamping foot lifts clear of the work and returns to its retracted position. Mounting fixture 81 may be clamped to table 1%. 19b in any desired position thereon by means of a toggle clamp 86 (see FIG. 4) so that the clamp 23 may be positioned where desired relative to work l to be clamped. This permits clamping of work W] of various sizes and shapes.  
  Referring now to FIG. 6, a schematic diagram of the pneumatic circuit for the loader-unloader l of this invention is shown interconnecting various air cyiinders. air switches and valves as heretofore described and as will appear. Briefly, the pneumatic circuit illustrated in FIG. 6 causes loader-unloader 1 and sewing machine 7 to operate in a predetermined operational sequence to first actuate clamps 23 to clamp work W1 to be sewn in a desired position on a respective table 19a. 19b, to lower pins 21 to their retracted position. to move the table inwardly from its retracted position to its loading position adjacent work holder 11 when the work holder is in a respective home position H1 or H2 and when clamping jaw 35 of the work holder is open. to close the clamping jaw. to return the table to its retracted position thereby to simultaneously deposit work W] to be sewn in the work holder and to remove previously sewn work W2 from the work holder. With the table re turned to its retracted position. an electrical signal is generated to energize the programmer 31 and to thus initiate operation of sewing machine 7 thereby to sew the work held by the work holder along its predetermined stitching line.  
  In FIG. 6, the various pneumatic components are shown connected by means of air lines L. The reference character P denotes that relatively high pressure air (cg, 7590 psi) is continuously supplied to a port in a pneumatic adjacent the reference character P.  
  V1, V2, V3 and V4 indicate manually or mechani cally tripped four-way valves. Valves V1 and V2 are each carried by tables 190 and 19b, respectively, and each is actuated by manual pushbutton 75. Valves V3 and V4 are carried by frame 41 and are adapted to be automatically tripped by a respective table 19a, 1% returning to its retracted position.  
  Valves C1. (2, C3 etc. are pneumatically actuated. normally closed three-way valves. Operation of these normally closed three-way valves will become apparent.  
  A1 and A2 indicate air actuated microswitches. These microswitches. when tripped. provide an electric signal to programmer 31 indicating that a respective table 19a. 19b is ready to be moved from its retracted position to its load position.  
  PVI, PVZ etc. indicate pilot actuated four-way air valves. The function of the various pilot valves will be more fully explained hereinafter.  
  O1 and 02 indicate normally open three-way valves. Like valve C1, C2 and C3, the purpose of these nor mally open valves will be explained hereinafter.  
  SVI, SVZ and SV3 indicate pneumatically operated shuttle valves.  
  TV1, TV2 and TV3 indicate manually operable tog gle valves which when in the position shown in FIG. 6 permit automatic operation of the loader-unloader. but when manually toggled permit independent operation of air cylinders 71 and 37.  
  S1, S2 and S3 indicate electrically operated four-way solenoid valves. Solenoid valves 5] and S2 are energized by electric signals generated by programmer 31. These signals are provided only after work holder 11 has moved to one of its home positions H1 or H2, after clamping jaw 35 has been opened. and after pushbuttons 75 have been actuated. Upon receiving the above mentioned electric signal. solenoid valve S1 or 52 effects movement of the appropriate table 19a. 1% from its retracted position to its load position. Upon a table moving to its load position. an electric signal is pro vided to solenoid valve S3 by means of a photocell PC] tripped by a blade 87 (see FIG. 4) carried by slide bearing 47 as the table moves to its load position. solenoid valve S3 then energizing cylinders 37 to close clamp jaw 35.  
  Operation of the loader-unloader of this invention is as follows:  
  With work holder 11 positioned in its first home position H1, (as shown in FIG. 1). and with a piece of previously sewn work W2 held in position on sewing platform 33 of work holder 11, an operator places pieces of cloth constituting work W1 to be sewn on the upper surface of table with the forward edge of the work in engagement with pins or stops 2] thereby to locate the work to be sewn in a predetermined position on the table. The operator then initiates operation of the of the loader by depressing air switch pushbutton 75 on table 190. Pushbutton 75 actuates valve V1 and supplies air pressure to a transfer port in normally closed valve C1 thereby to shift its spool and trip air ac tuated microswitch A1, and to supply pressurized air to the pilot ports of pilot air valves PVl and PV3. Air cylinders 71 for stops 2] are normally pressurized to maintain the pins in their raised position. Upon shifting of the spool of the valve PVl, the cap end of air cylinder 7] is vented via shuttle valve SV] and toggle valve TVl and air pressure is supplied to the rod end of air cylinder 71 via the toggle valve TVl thereby to forcefully move pins 21 to their lowered retracted position below their respective table 19a. 19b.  
  Simultaneously. the spool of pilot valve PV3 is shifted to supply air pressure to clamp cylinders 77 thereby to move clamps 23 on table 19a from their unclamped to their clamped positions. Table 190 is now ready to be moved from its retracted to its load position.  
  Upon an appropriate electrical signal being supplied to solenoid valve 5! indicating that work holder 11 is properly positioned in its home position HI and that work W! is in position to be loaded, actuation of this solenoid valve supplies air pressure to a transfer port of normally closed valve C3 and to a transfer port of normally open valve 01. The opening of valve (3 causes air under pressure to be directed to the rod end of cylinder 61 thereby to move table 190 from its retracted position to its load position (i.e. from its FIG. 5A to its FIG. 58 position). It will be understood that air cylinders 61 for table 19a. 19b each are equipped with pneumatic flow control devices and are cushioned thereby to smoothly start and stop the tables as they move between their retracted and load positions. Simultaneous with the energization of cylinders 61, normally open valve 01 closes and thereby vents the other pilot port of valve PV3 thereby to effect the release of clamps 23. It will be understood that clamps 23 do not release the work W1 until table 190 has attained its load position.  
  As table 19a moves to its load position. blade 87 carried by the slide bearing 47 actuates photocell PCl thus generating an electric signal which energizes solenoid valve S3 and deenergizes solenoid valve 51. Upon energization of solenoid valve S3, low pressure air from regulator R1 is supplied to cylinders 37 via shuttle valve TV3 and a toggle valve 5V3 thereby to close clamping jaw 35. This causes the clamping jaw 35 to move downwardly from its raised retracted or open position toward its clamped or closed position and thereby to engage work Wl supported on the upper surface of table 190. Continued closing movement of clamping jaw 35 under relatively low air pressure (e.g.. l-l5 psi), causes table 190 to tilt downwardly (see FIG. C), and to cause gripper pad 73 on the bottom face of the table to engage the previously sewn work W2 on sewing platform 33. Upon the closing of clamping jaw 35, solenoid valve S] is deenergized thus allowing normally closed valve C3 and normally open valve ()1 to return to their positions as shown in FIG. 6 thus venting the rod end of the cylinder 6| and applying pressure to the cap end thereof to extend its piston rod and thereby to effect movement of the table from its load position to its retracted position (see FIGS. 5C and 5D). As the table returns to its retracted position (FIG. 5A), gripper 39 on clamping jaw 35 holds work W1 and causes it to slide from the table onto sewing platform 33 in a predetermined sewing position and gripper pad 73 on the bottom face of the table pushes the previously sewn work W2 from the sewing platform into air conveyor 43. Thus, the table slides out from under the new work being loaded in the work holder, and slides the completed work off the platform 33. Upon complete withdrawal of the table, work W1 is held by the clamping jaw 35 in its sewing position on platform 33 and upon movement of the leading edge of the table clear of the clamping jaw, spring 65 biases the table upwardly to return it to its initial titled (e.g., 5) position. Upon return of the table to its starting position, blade 87 trips a photocell PC2 (see FIG. 4) to provide a signal to programmer 3! that the table is clear of the work holder with the cloth to be sewn positioned in the work holder whereby the work holder may be moved relative to needle 9 for sewing of the work. As the leading edge of table 190 moves clear of the work holder, a delay circuit including a flow control device FC and an air tank T provides a delayed pressure signal to the pilot port of pilot valve P5 thereby to shift the spool in the pilot valve and to apply high pressure (e.g., psi) to shuttle valve 5V3 thereby to shift its spool and to direct high pressure air to air cylinders 37 thereby to increase the clamping force on the cloth to securely hold it in position on sewing platform 33. Upon completion of stitching of work W], the work holder moves generally later ally with respect to the sewing machine to its second home position H2. It will be understood that during the sewing of a piece of work. the operator places a second piece of work to be sewn on the table 19b. Upon the work holder moving to its second home position after completion of sewing work, clamping jaw 35 automatically opens to release the previously sewn work and the operator depresses pushbutton 75 on 19!; thereby to effect the next load-unload cycle.  
  It will be understood that the loader-unloader l of this invention enables work to be accurately and rapidly placed in the work holder and to simultaneously remove previously sewn work therefrom. It will be particularly noted that work holder 11 moves generally laterally with respect to sewing machine 7 as the work is stitched so that upon completion of sewing of the work, the work holder is relatively close to the home position on the opposite side of the sewing machine from which it started. Thus, as it moves from one home position to its sewing or operating position and thence to its other home position the work holder need not be returned the entire length of the sewing apparatus to unload the completed work and to have other work loaded thereon. This aids in speeding production of automatic sewing apparatus. Also. the provision of two tables 19a, 191) allows the operator to load the next piece of cloth to be sewn while the sewing machine is stitching a previously loaded work. Thus, as soon as the work holder returns to a home position, the load-unload cycle may be immediately initiated further saving production time. It will be understood that air cylinders 77 for clamps 23, air cylinders 37 for clamp jaw 35 and air cylinders 61 for moving tables 190 and 19b are so sized and the air pressure supplied thereto is so regulated as to not exsert excessive forces and thus reduce the possibility of injury to the operator.  
  In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.  
  As various changes could be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be illustrative and not in a limiting sense.  
 What is claimed is:  
  l. A loader-unloader for automatic sewing apparatus. said automatic sewing apparatus comprising a sewing machine having a needle, a work holder for holding work to be sewn, means for effecting relative movement of the work holder and the sewing machine to stitch the work held by the work holder along a predetermined stitching line, said loader-unloader comprising transfer means on which work to be sewn may be positioned for being transferred to said work holder, means for locating the work on said transfer means in a predetermined position, means mounting the transfer means for movement from a retracted position relative to the work holder to a load position relative to the work holder. means for retaining the work in the work holder as the transfer means returns to retracted position, and means on the transfer means for engaging previously sewn work in the work holder and removing it from the work holder as the transfer means returns to retracted position.  
  2. A loader-unloader as set forth in claim 1 further having means for holding said work on the transfer means in said predetermined position.  
  3. A ioader-unloader for automatic sewing apparatus. said automatic sewing apparatus comprising a sewing machine having a needle, a work holder for holding work to be sewn, means for moving the work holder and the work held thereby along a predetermined path relative to the needle to stitch the work along a predetermined stitching line. said loader-unloader comprising transfer means on which work to be sewn may be positioned for being transferred to said work holder, means for locating the work on said transfer means in a predetermined position. and means for moving said transfer means for transferring the work to be sewn to said work holder and for removing previously sewn work from the work holder. further having means for holding said work on the transfer means in said predetermined position, said work holder being movable relative to the sewing machine from a home position in which work held by the work holder is clear ofsaid needle and in which work may be loaded on and unloaded from the work holder for stitching said work along said predetermined stitching line, and said transfer means being positioned relative to the sewing machine for transferring the work to be sewn to the work holder and for removing previously sewn work therefrom when the work holder is in its home position.  
  4. A loaderunloader as set forth in claim 3 further comprising means for conveying away previously sewn work unloaded from the work holder.  
  5. A loader-unloader as set forth in claim 3 wherein said work holder is movable generally laterally with respect to the sewing machine to and from a first home position at one side of the sewing machine to its operat ing position. and upon completion of stitching of said work is movable to a second home position on the other side of the sewing machine. said work being clear of the needle of the sewing machine with said work holder positioned in either its first or second home position, and wherein said transfer means further comprises a first transfer member positioned adjacent said first home position and a second transfer member positioned adjacent said second home position, each of said transfer means having means for moving its respective transfer member for transferring the work to be sewn to said work holder and for removing previously sewn work, said first transfer member being operable to load a first piece of work onto the work holder and to unload a previously sewn piece of work from the work holder at said first home position. said work holder being movable for stitching of the work along said predetermined stitching line and upon completion of stitching being movable to its second home position and said second transfer member being operable to load a second piece of work to be sewn on the work holder and to remove the completed first piece of work from the work holder at said second home position.  
  6. A loader-unloader as set forth in claim 3 wherein said transfer means comprises a table, and said means for moving said transfer means includes means for supporting said table adjacent said home position and for moving said table from a retracted position in which the table is clear of said work holder. and in which work to be sewn may be placed on said table in said predetermined position, to a load position in which the work to be sewn is positioned for being held by said work holder. and for then returning said table to its re tracted position thereby simultaneously to deposit work from the table on the work holder in a predetermined sewing position relative to the work holder and to unload previously sewn work from the work holder.  
  7. A loader-unloader as set forth in claim 6 wherein said work holder comprises clamping means having an open position for receiving work and a closed position in which work is clamped in said sewing position, said clamping means being movable from its open position toward its closed position and when said work holder is in its home position and when said table is in its load position thereby to engage work carried by the table and to hold it relative to the work holder in its sewing position as the table returns to its retracted position.  
  8. A loader-unloader as set forth in claim 7 further comprising means on said table for engaging said previously sewn work on said work holder for removing it from the work holder as said table returns to its retracted position.  
  9. A loader-unloader as set forth in claim 8 further comprising means for conveying away completed work removed from the work holder.  
  10. A loader-unloader as set forth in claim 8 wherein said table when in its load position is movable down wardly thereby to engage previously sewn work on the work holder and to remove said previously sewn work from the work holder upon movement ofthe table from its load position to its retracted position.  
  ll. A loader-unloader as set forth in claim 10 wherein said clamping means is engageable with work carried by said table with said table to tilt said table downwardly when said table is in its load position upon movement of said clamping means from its open position toward its closed position, whereby upon movement of the table from its load to its retracted position the work to be sewn is held relative to the work holder by said clamping means and. after movement of the table clear of the work holder, is held clamped in its sewing position on the work holder.  
  [2. A loader-unloader as set forth in claim 6 wherein said work locating means comprises at least one stop projecting up above the surface of the table when the latter is in its retracted position for locating the work on the table in said predetermined position, said stop being clear of said table when the table is in its load position thereby to permit the work to be sewn to be de&#39; posited on said work holder.  
  13. A loader-unloader as set forth in claim 12 further comprising means for effecting movement of said stop and table relative to one another between a locating position in which said stop extends up above the upper surface of said table when the latter is in its retracted position thereby to locate work to be sewn in said predetermined position and a retracted position in which the stop is clear of said workpiece.  
  14. A loader-unloader as set forth in claim 12 wherein said stop is adjustable relative to the retracted position of the table to vary the predetermined position of the work on the table and to accommodate pieces of work of various sizes and shapes.  
  [5. A loader-unloader as set forth in claim 6 wherein said means for holding said work on said transfer means comprises at least one clamp carried by said table movable relative to the table between an unclamped position in which it is clear of the workpiece to be sewn when the work is in its stated predetermined position on the table and a clamped position in which it is engageable with the work to hold the latter in its stated predetermined position on the table as the table is moved from its retracted position to its load position.  
  16. A loader-unloader for automatic sewing apparatus. said automatic sewing apparatus comprising a sewing machine having a needle. a work holder for holding work to be sewn. means for moving the work holder and the work held thereby along a predetermined path relative to the needle to stitch the work along a predetermined stitching line, said loader-unloader comprising transfer means on which work to be sewn may be positioned for being transferred to said work holder. means for locating the work on said transfer means in a predetermined position, and means for moving said transfer means for transferring the work to be sewn to said work holder and for removing previously sewn work from the work holder. further having means for holding said work on the transfer means in said prede termined position. said transfer means comprising a table on which said work is positioned and said means for moving the transfer means comprising means for supporting the table adjacent said work holder when the latter is in a home position and for moving said table between a retracted position in which said table is clear of said work holder and a load position in which said work on said table is in position for depositing said work on said work holder.  
  17. A work holder as set forth in claim 16 wherein said moving means further comprises power operated means actuable for effecting generally translational movement of said table between its retracted and load positions.  
  IS. A loader-unloader as set forth in claim 17 wherein said means for supporting the table comprises a frame. means carried by the frame for guiding said table between its retracted and load position, and wherein said moving means further comprises linkage means interconnecting said power operated means to said table thereby to effect translational movement of the table upon actuation of said power operated means.  
  19. A loader-unloader as set forth in claim 17 wherein said guide means comprises a guide bar carried by the frame and extending generally parallel to the direction of movement of the table between its starting and load position and a slider carried by the table slidable along said guide bar.  
  20. A loaderunloader as set forth in claim 19 wherein said power operated means comprises a fluid power unit interconnected between said frame and said linkage means actuable to effect movement ofthe table between its retracted and loading position.  
  21. A loader-unloader as set forth in claim l6 wherein one end of said table adjacent said work holder is tiltable downwardly when the table is in its load position from a raised position in which said one end of the table is clear of previously sewn work supported on the work holder and a lowered position in which said one end of the table is engageable with said previously sewn LII work whereby upon movement of the table from its load position to its starting position said previously sewn work is removed from the work holder.  
  22. A loader-unloader as set forth in claim 21 wherein said table includes means on the bottom thereof at its said one end for engaging said previously sewn work.  
  23. A loader-unloader for automatic sewing apparatus. said automatic sewing apparatus comprising a sewing machine having a needle, a work holder for holding work to be sewn. and means for moving the work holder and the work held thereby along a predetermined path relative to the needle to stitch the work along a predetermined stitching line, said work holder comprising a platform for supporting the work and a clamp movable between a raised open position and a lowered closed position for clamping work on the platform with the margin of the work clear for being sewn, said platform and clamp being movable relative to the sewing machine from the home position in which work held by the work holder is clear of said needle and in which work may be loaded on and unloaded from the work holder for stitching said work along said predetermined stitching line, said loader-unloader comprising transfer means on which work may be positioned for being transferred onto said platform when the platform is in its home position, said transfer means comprising a table and means for moving the table from a retracted position in which the table is clear of said work holder and in which work to be sewn may be placed on the table in a predetermined position, to a load position in which work is positioned for being loaded on said platform. and for then returning said table to its retracted position thereby simultaneously to deposit work from the table on the platform in a predetermined sewing position relative to the platform and to unload previously sewn work from the platform. said table being movable over said platform as said table moves between its retracted and load position. said clamp being movable from its open position toward its closed position for engagement with the work carried by the table and with the table to tilt the table downwardly when the table is in its load position thereby to cause said table to engage previously sewn work on said platform. whereby upon movement of the table from its load to its retracted position the work to be sewn is held relative to the platform by said clamp and said previously sewn work is removed from the platform and. after movement of the tray clear of the platform, the work to be sewn is held clamped in its sewing position on the platform. said loader&#39;unloader further comprising means for conveying away completed work removed from the platform.  
  24. Automatic sewing apparatus comprising a sewing machine. a work holder. means for effecting relative movement of said sewing machine and work holder for stitching work held by the holder. and transfer means for loading the work holder with work and unloading work from the work holder, wherein the work holder comprises a platform and means for clamping work on the platform, and the transfer means comprises a table movable between a retracted position and a load position relative to the work holder. said table being adapted for placement of work thereon where in its retracted position and for bringing the work to the work holder when moved to its load position. said clamping means being engageable with the work on the table when the table is moved to its load position to cause the neath the clamping means. the clamping means being engageable with the work on the table as the table moves back to its retracted position to hold the work while the table moves out from under the work, and said apparatus having means mounting the table for downward movement by the clamping means for engagement of said means on the table with the previously sewn work to move said previously sewn work off the platform as the table moves back to its retracted the platform. the table, in its load position. extending 10 position.  
 over previously sewn work on the platform and under-