CA2331506A1 - Vertical stitching machine and method - Google Patents

Abstract

A stitching machine (10) and method orients cooperating needle (54) and hook (56) components in spaced horizontal alignment, suspends and tensions flexib le sheets (57) to be stitched in a generally vertical orientation between the components for stitching interior seams through the flexible sheets. Horizontal and vertical slides (22) support the cooperating sewing machine components along a horizontal and a vertical axis parallel to the sheets. Controlled drives shift the components in unison along these axes for formin g sewn patterns on the sheets. A conveyor (68) is provided with a substantiall y vertical run, of a height in excess of that of the sheets, to pass the sheet s to be stitched between the sewing components and hold the sheets in the vertical orientation.

Description

WO 99/751 PCTN598l09pB8 n..c.x~xven!:v. ox rgx z~v~rr=oR
The common bed quilt typically will have a mat or equivalent fill of lightweight open-cell or porous material sandwiched between more durable and/or attractive cloth or fabric sheets. Such quilts can be cozmnercially made by initially seaming the layered components together at the perimeters, and then by sewing or stitching them together along patterned seams spaced -inwardly from the perimeters. Othe7c products having layered cloth or fabric sheets without any sandwiched fill, or even a single sheet can also have related interior patterned seams or etitchings for holding the sheets together and/oz~ fdr merely decorative purposes.
Most commercial machines for quilting or stitching fabric sheets utilize a.perimeter frame to which the flexible eheet(s) when stretched flat could be clamped.
The sheet frame, while aligned horizontally, would then be manipulated to position its clamped sheets) between the opposed upper or needle head and 7.omer hook or base components of a sewing machine, which would stitch through the sheets) to complete the patterned interior seams. To accommodate this, perpendicularly arranged ''X°
axis and "Y" axis guide tracks are provided for the sheet frame and/or sewing machine, suited thereby upon specific combinations of relative "X" axis and "Y" axis movements between the sheet frame and sewing machine for generating the desired patterned seams.
SUB5T1TUTE SHEET (Rule Z6) WO 991Se9'I51 PCfN598ro9068 oae such type of stitching machine ha~a the vertically separated and opposed needle head and base components of the sewing machine horizontally stationary, ' and the sheet ~rame and clamped sheetfs) only are moved horizontally along "X" and "Y" axes relative to and between the opposed operating sewing machine components . ,;
to trace out the patterned seams on the clamped sheet(s), However, to provide complete patterned seam coverage over most of the sheet interior, the guide track and/or fra~nd structure and/or clearance apace for actual sheet frame movements need be extended horizontally to approximately four times the size of the sheet frame. An improved type of stitching machine further provides that the opposed sewing machine head and base components are moved in unison alone the "X" axi.~ or side to side of the sheet frame, reducing the size requirements of the stitching machine frame by almost one-half while yet being approximately twice the size of the sheet frame. Another improved type of stitching machine further moves the sewing machine'along the "Y" axis or lengthwise of the sheet frame, reducing the size requirements of the stitching machine again by almost one-half but yet being more than the sheet fxame itself.
Thus, as the clamped aheet(s) are stretched out to full size and are oriented horizontally when being stitched in most if not all existing interior seam stitching machines, such stitching machines require floor space larger than the flexible sheet goods or quilt itself, and frequently several times larger than this minimum size. Moreover, additional Floor apace at least SUBSTITUTE SHEET (Rule 26) wo 99~sa~si Pcrius9so~oas 3 ' as large as the sheet frame is typically needed for supporting the sheet frame when it is outside of the stitching machine, as when the flexible sheets) is clamped to or removed from the sheet frame.
g~ltY OR Z'R7~: II~TVElvf'1'I~lr1 This #.nvention relates to a machine fox and method .
of atitChing interior patterned seams on flexible fabric sheet goods, specifically including on quilts. ~~
A basis object of this invention is to provide an improved stitching machine and its method of sta,tching that greatly reduces the needed flour space requirements therefor, compared to prier art stitching machines.
A specific feature of the invention is an improved method of stitching flexible sheets) along interior patterns or seams spaced from the perimeter of the sheet(s), which comprises having the sheets) oriented substantially vestically.during such stitching. The working tool or stitching machine is guided along the "X"
or horizontal axis and "Y" or Vertical axis, in a controlled manner dictated by conventional drives and controls. The vertical orientation of the work piece or sheets) allows for a stitching machine to practice the method with frame width reguiremencs comparable to the width of the sheets) being stitched, but less than and virtually independent of the length of the sheets) being stitched, reducing the otherwise horizontal floor space requirements of such stitching machine.
Atnother specific feature of the invention is to provide a horizontally compact stitching machine and SUBSTITUTE SHEET (Rule 26) wo ~isa~si PG'fNS98I09088 conveyor therefor, suited to move the sheets) to be stitched through the machine and past the sewing machine componerate to then be operated automatically by conventional controls, yielding a stitching machine and method that can be practiced by leeo than a full-time operator, meaning that one operator will be able to handle the work demands of several like simultaneously operated stitching machines clustered around the operator. ,, These and other objects, features or advantages of the invention will be more fully understood and appreciated after consideration of the following description of the invention, which includes as a part thereof the accompanying drawings, wherein:
Fig. 1 ~.s a perspective view of a stitching machine suited far operation according to the inventive method, whexe no external panels are illustrated for Clarity of disclosure of the underlying operative components;
Fig. z is a perspective view of bridge structure of the stitching machine of Fig. Z, from a steeper viewing angle;
Fig. 3 is an enlarged sectional, view as peen from lines 3-3 in Fig. 2;
Fig. 4 is a top view of a platform drive used on the bridge structure of Fig. 3;
Fig. S is a side view of a conveyor cross bar and a typical sheet grip carried thereon;
SUBST~TU1'E SHEET (Rule Z~

WO 99/58751 PCTN$9s/0905B
Fig. 6 is a top view of the bridge-side columa mounting and'drive, and of side Clamp structure utilized in the stitching machine of Fig. 1;
Fig. 7 is a side elevational view of part of the side clamp structure of Fig. 6, and of a bottom clamp structure utilized in the stitching machine of Fig. 1.
DE?AILEa DESCRIBTION OF A pREFB'ttRED
~ODIMENT OF TA'E INV~1T eu ., The specific stitching machine to to be disclosed now represents a preferred embodiment that will readily serve to operate according to the inventive method. For clarity and ease of disclosure, not all components or specific details of a component ate illustrated in all figures where such might appear and be adequately illustrated in another figure; and conventional components may not be illustrated in precise details.
The stitching machine l0 has a frame 12 comprised of base Z3 and front vertical side columns 14 and rear vertical side columns 16 upstanding from the base_ A
cross bridge 22 comprised of horizontally separated front and rear beams 24, 26 extended between end members 28 terminates proximate the rear vertical columns 16, and guide means 30 cooperate between the bridge end members 28 and rear vextical columns 16 to restrain the bridge 22 to move vertically along the rear side columns 16 w3.th the. bridge beams 24, 26 aligned generally horizontally.
Drives 32 move the bridge end members 28 in precise unison vertically along the side Columns 16,~maintaining the bridge in horizontal alignment.
SUBSTITUTE SHEET (Rule Z6) WO 99/58751 ~ ' ' PCIYU598~09p88 Counte~reighte 36 are guided vertically along the rear vertical columns 16 by conventioaal means (not shown), and cables 38 trained over pulleys near the top of the aide aolun~s 16 connect the counterweight and cross bridge together, to off-set the gravity bias of the bridge 22 during its vertical movement.
Mounting platforms 44, 46 are carried on the front and rear bridge beaeua ~4, 26 respectively, and guide means 4o cooperate between the platforms and bridge beams . .
to allow the plaCtorm zo be moved along the beam lengths generally between the bridge end members 2B. Drives 42 are provided to move the platforms 44, 46 simultaneously in precise unison along the beams, maintaining them directly opposed to one another sad horizontally aligned.
~ separate drive 42 will be provided for each bearn-platform, and in the embodiment illustrated includes a rack 43a secured to the beam and engaged by a pinion 43b driven by a gear motor 43c carried on the platform 44 or 46. The drives 32 for the bridge 22 can be similar, with separate racks secured to the different vertical rear side columns ~.6 and the pinions and gear motors being carried off of the opposite bridge end members 28.
Mounting platform 48 is carried on the front beam platform 44, and guide means SO cooperate between the platforms 44, 48 to move the platform 48 only in the direction normal to the beam length and/or the movement of the platform 44 along the beam 24. A linear drive 52 such as an air cylinder connected between the platforms 44, 48 powers the platform 48 toward and away from the rear platform 46 when needed.
SUBSTITUTE SHEET (Rule 26) wo ~ise~si Pernrs98rososs Cooperating coteponents 54, 56 of a conventional sewing machine 58 are carried respectively on the front and rear beam mounting platforms 44 (via platfot~n 48) and 46; the component 54 generally being the needle or head component and component 56 being the hook or base component of the sewing machine. The sewing machine needle and hook components 54, 56 are thus spaced apa~ct horizontally as illustrated in Fig. 3 suited to allow the passage therebetween of flexible sheets) tp be stitched (shown only in phantom as 57), and drive 52 allows movement of the needle component 54 horizontally toward and away from the hook component 56, suited when brought together to be in operative opposed and proximate cooperation for stitching through the sheets) 57 to form '.
she intended interior patterned seams, An endless loop conveyor system 60 is provided on the fraete 12, having separated drive belts 61 extended as .
front and rear vertical~runs 62, 64, and lower and upper horizontal xuns 63, 65, with the plane defined by the rear vertical run 64 apecifieally passing between the opposed needle and hook sewing machine components 54, 56, Horizontal cross bar 68a, 68b and 68c are connected between the drive belts 61, each having clamps 7D thereon suited to grip and hold a stretched leading end of the r flexible fabric sheet(e) to be stitched in the machine 10; before, during and even after such stitching.
Horizontal rolls 74 are also mounted near the front and rear, and upper and lower corners between the directional conveyor runs 62, 63,. 64, 65, to guide and/or support the carried sheetls) around the loop corners. The rolls 74 SUBSTrTtJTE SHEET (Rule 26~

wo mseysi ~N~~s can be powered to rotate at a peripheral speed .corresponding to the travel speed of the conveyor system.
Horizontally extended supports (not shown) can also be positioned under both the lowei sad upper horizontal loop runs 63, 65 fot supporting the flexible sheets) passing such locations.
The effective vertical height of the rear conveyor run 64 exceeds the length of the fabric sheets) to be stitched, whereby the trailing portions of the fabric ~~' sheec(s) can suspend or hang vertically below the clamping cross bar 68c when near the top of the teat vertical conveyor run 64, including passing between the opposed needle and hook sewing machine components 54, 56.
The width of the conveyor system, including the length of the c7,amp bars 6Ba, 68b, 6ac exceeds the width of the flex~.ble sheet (~s) to be stitched.
Bide clamps 76 (Figs. 6 and 7) are provided on the frame 12 to extend along~the opposite aides of the rear vertical conveyor run 64, each clamp being comprised as elongated bars 77a, 77b horizontally separated and aligned to overlap opposite front and rear sides of the sheets) (in phantom as 57) as suspended from the cross bar 69c, extended also between the tog leading and bottom trailing edges of the sheet(s). Linear drive or air cylinder 78 can be actuated to shift clamp bar 77a toward clamp bar 7'7b, tv grip the vertical side edges of the sheet(s). Linear drive or air cylinder 79 can then be actuated to slightly separate the opposite side clamps horizontally in the plane of the suspended sheets) to stretch them tightly aide-to--side, Bottom clamp eo SUBSTITUTE SHEET (,Mule 26) WO 99/51'151 PGT/IlS98In90EE

comprised of horizontally opposed bare 81a, 91b can .further be provided on the frame la along the bottom trailing edge of the suspended sheet(s), with air cylinder 82 powering bax 81a transverse to the suspended sheets) to grip the bottom thereof. once gripped, the conveyor system.60 can be inched veztxcally upward to stretch the eheetls) tightly top-to-bottom or leading edge-to-trailing edge.
A preferred endless conveyor sy8tem overall loop length will slightly exceed three times the length of the flexible sheets) to be stitched, whereby three cross bars 68a, 68b, 68c can be provided equally spaced apart on the conveyor loop, each being advanced one-third of the way around the loop during the index cycle of the conveyor system. Further, the loop size can proportioned so that the positions of the three cross bare after each conveyor index will be positioned respectively as 68a at the front load position ~in the front vertical loop run 6Z, as 68b at a ready but pre-stitching position near the bend or juncture between the lower horizontal loop run 63 and the rear vertical run 64, and as 68c at the operative stitching position near the upper end of the rear vertical run 64.
The stretched leading end of the flexible eheet(s) to be stitched can be secured, manually or otherwise, to the conveyor cross bar at the 68a position stopped at a ' comfortable height spaced above the floor. One conveyor system index advances the cross bar to position 68b, carrying the leading end of the flexible sheets) with it, initially by moving the bar downwardly from the SUBSTITUTE SKEET (Rule 26) wo ~~ss~s~ ecrrt~s~sro~oas initial clamping position to the bottom of the front vert~.cal run 62, and then =earwardly along the lower hor~.zontal run 63 toward the rear vertical run 64. The next conveyor index upwardly advances the cross bar to ~' the 68e position near the top of the rear vertical rvn 64. The stitched sheets) will be carried with the next conveyor index back to the 68a position. ' with the disclosed stitching machine 10, vne operator can easily remove a stitched sheet product frdml the clamp bar at position 68a, and then clamp another pre-stitched sheets) onto the same cross bar; while the immediately preceding cross bar 68b is in the ready position near the lower end of the loop run 54, while the next preceding cross bar 68c ie at the top of the rea;
vertical run and its clamped sheets) might be stitched.
As the typical stitching cycle for making the patterned seams on the sheet(a) can take between approximately one and even can minutes, one~operator likely will be able to simultaneously take care of several eTuetered stitching machines,. moving troth one machine to another, for greatly reduced labor coats for performing such seam stitching.
This can be contrasted against moat conventional stitching machines that utilise a sheet frame and typically reguire one operator fvr each machine.
One important aspect of the diselvsed stitching machine to and the incorporated method is that the pre-atitched flexible aheet(s) can be loaded d~.rectly onto the conveyor system 60 and then be carried thereby to suspend or dangle freely along a substantially ve=tical plane,-whereupon the sheet(e) can be racked or stretched SUBSTITUTE SKEET (Rule 26) wo ~~se~s~ ~crius9ero9oes out along both the ~X" and "Y" axes and secured along its peripheral edges_in a pre-stitching condition; so that stitching of the sheets) can take place. This vertical orientation of the aheet(s) during stitching allows the front-to-rear horizontal. space requirements or depth of the stitching machine to be significantly reduced, compared to commercially available stitching machines that stitch the sheets) supported in a horizontal plane by a sheet frame. Specifically, the overall front-to,~' rear horizontal space requirements or depth of the stitching machine itself can be reduced to pogeibly one-sixth or one-third the corresponding size of the smallest commercially used existing stitching machine.
Moreover, the distinctive stitching machine and method operates without a supplemental sheet frame for holding the sheets) during and after the stitching, and the needed floor space outside of the conventional st~,tching machine for racking the pre-stitched eheet(s) .
and removing the stitched sheet goods.
Additional specifics of the drives 32, 42 mentioned herein will now be discussed. Drive 32 must move the opposite ends of the bridge 2z vertically in precise unison, to keep the bridge 22 in horizontal alignment.
Drive 42 must move the beam_platforms 44, 46 in precise unison along the length of the bridge beams Z4, 26, to .
provide that the sewing machine components 52, 54 remain in proper cooperation, exactly horizontally aligned and opposed to one another. To provide for this, the drives 32, 42 can include positive and accurate positional ' linkages having minimal free play, such as the SUBSTITUTE SHEET (Rnle 26) wo 99~sns~ rcr,~us9sro9os~
12 .
illustrated preci~s~.on .xack and pinion drives, or with high tolerance ball screw mechanisms. Further, drives ate to be controlled as part of servo rnechaaisms that use the position, direction of movement, or orientation of the components as process variables and detect any variance from set po3nt.a or target values, and via feedback of the detected differences readjust the input to the drives. Servo mechanisms and eontxola of this type specifically are provided by Yaskawa Electric America, Ins. having offices at 2942 MacAtthur~, Northbrook, IL 60062, particulazly suited for use in Ghe disclosed stitching machine.
Further, the cooperating opposed needle head~and base components of the sewing machine are maintained and operated in precise unison, both as to the speeds and positions of the components, by the use of such servo mechanisms and feedback controls, specifically including the use of master-slave 'interlock of the separate motors powering the separate respective components. This allows the controlled operation of the separate component motors while being separated on opposite sides of the sheets) during sti,tchiz~g, and without mechanical drive linkages between the motors.
Conventional photocell components (not shown? can be positioned adjacent the vertical rear run 64 of the conveyor system near the upper end thereof, suited to detect Che leading edge of the gripped sheets) suspended from Che clamp baz~ and to stop the conveyor advance or indexing as such approaches the proper stitching position. Once stopped, the bottom gzipper mechanism 80 SUBSTTfZfTE SHEET (Rule 26) WO 99/5ff51 PCTNS98/0908~

can be actuated to hold the trailing edge of the suspended sheet(s). Inched advancing movement of the conveyor can stretch the suspended sheetls) vertically or along the ~Y" axis_ Actuation of the clamp 76 can grip the aide edges of the suspended sheet(s), and of the drive ~9 can stretch the sheet(e) horizontally or along the "X" axis. All of these racking steps can be carried out automatically by means of eeasors and/or computer controls now used in the stitching machine art. Also,'' once the sheets) are suitable racked in the vertical orientation along the conveyor run 64, the sewing machine can be shifted automatically along the ~X" and ~~Y" axes as needed via actuation of the respective drives.42 and 32 to trace out the intended seam pattern, again by uBing conventional computer eontrole.now used in the stitching machine art.
while a specific embodiment has been illustrated, it will be obvious that minor changes could be made therefrom without departing from the spirit of the invention. Accordingly, the invention is to determined by the scope of the following claims.
SUBSTXTUTE SHEET (Rule 26)

Claims (13)

1. A stitching machine for making interior seams.
through flexible sheet(s), comprising the combination of a sewing machine having cooperating needle and hook components;
a conveyor having a substantially vertical run passing between the cooperating sewing machine components, and of a height in excess of the sheet(s) to be stitched;
the conveyor having means thereon to releasibly retain the leading edge of the sheet(s), and to move said leading edge to near the upper end of said vertical run and thereby have the remainder of the sheet(s) hanging vertically therebelow along the conveyor run and between the sewing machine components;
means to releasibly retain the trailing and side edges of the sheet(s) while along the vertical conveyor run, and to stretch the sheet(s) along the vertical or "Y" axis and the horizontal or "X" axis to a generally flat stitchable condition;
means to shift the cooperating sewing machine components in unison along the "X" and "Y" axes as needed to trace out an intended seam pattern relative to the flexible sheet(s); and means to move said retained leading edge from said vertical conveyor run for removing the stitched sheet(s).

2. A stitching machine according to claim 1, further comprising the conveyor being an endless loop having a substantially-uniform width greater than the width of the flexible sheet(s) to be stitched and having a length at least twice the height of the vertical run and defining in addition to the vertical run a second run not passing between the cooperating sewing machine components, and the conveyor having separate means thezeon on releasibly retain the leading edges of different sets of the sheet(s) respectively at the vertical and second runs, whereby one set of flexible sheet(s) can be at the vertical run for being stitched while another set of flexible sheet(s) can simultaneously be at the second run for being retained on or removed from the conveyor.

3. A stitching machine according to claim 1, further comprising the conveyor being an endless loop having a substantially uniform width greater than the width of the flexible sheet(s) to be stitched and having a length slightly exceeding three times the height of the vertical run, and the conveyor having at substantially equal apacings around the loop separate means thereon to releasibly retain the respective leading edges of three sets of the sheet(s) simultaneously at substantially equal spacings around the loop, whereby the different sets of flexible sheet(s) can be respectively, being stitched, being retained on or removed from the conveyor, or waiting for being stitched or being removed.

4. A stitching machine according to claim 3, further comprising the conveyor endless loop being proportioned so that the positions of the separate means on the conveyor to releasibly retain the leading edge of the sheet(s), after each indexing of the conveyor loop, will be positioned respectively at a stitching position near the upper end of the vertical run, at a pre-stitching position near the lower end of the vertical run, and at an accessible comfortable height position spaced above the floor for retaining/removing the flexible sheet(s) relative to the conveyor.

5. A method of stitching interior seams through flexible sheets, comprising the combination of utilizing a sewing machine having separated but cooperating needle and hook components and orienting the components in generally horizontal alignment, holding the sheets along respective top edges thereof and elevating the top edges in a vertical direction to suspend the underlying remainder of the sheets in a general vertical orientation passing between the cooperating sewing machine components, holding the respective opposite side edges and the bottom edges of the sheets and biasing them apart for tensioning the sheets to a generally flat stitchable condition yet in the vertical plane, and moving the cooperating sewing machine components in unison along horizontal and vertical axes parallel to the vertical plane as needed to trace out and stitch the seams through the flexible sheets.

6. A method of stitching interior seams through flexible sheets according to claim 5, further comprising indexing the flexible sheets by the held top edges thereof in a horizontal direction and laterally of the vertical plane defined by the flexible sheets suspended between the cooperating needle and hook components of the sewing machine, toward the plane before having the seams stitched and away from the plane after having the seams stitched.

7. A stitching machine for making interior seams through flexible sheets of set lengths and widths, comprising the combination of:
spaced vertical side columns, a cross bridge extended between the side columns, and means connecting the cross bridge for movement vertically along the side columns;
said cross bridge comprising horizontally separated front and rear beams, mounting platforms and means connecting the mounting platforms for movement horizontally along the front and rear bridge beams respectively, and a component platform and means connecting the component platform for movement horizontally on one of the mounting platforms in the direction substantially normal to the bridge beams and toward and away from the other mounting platform;
a sewing machine having cooperating needle and hook components, the cooperating needle and hook components being connected to the other mounting platform and to the component platform and being horizontally separated and aligned and means to drive these platforms and the cooperative sewing machine components thereon horizontally as needed to be separated and to be in operative stitching proximity;
means to hold peripheral edges of the flexible sheets to be stitched and to stretch out the sheets to a generally flat stitehable condition vertically aligned and passing between the cooperating sewing machine components;
the maximum available vertical movement of the cross bridge along the side columns and the maximum available horizontal movement of the mounting platforms and sewing machine components carried thereon being in excess of the lengths and widths of the stretched flexible sheets as held and vertically aligned; and means to drive the cross bridge vertically along the side columns while maintaining the cross bridge in precise horizontal alignment, means to drive the mounting platforms and cooperative sewing machine components along the bridge beams in unison for maintaining the operative components in precise operative horizontal alignment, and means to operate these drive means as needed so as to shift the cooperating sewing machine components in unison along the horizontal and vertical axes and thereby trace out an intended seam pattern relative to the vertically aligned flexible sheets.

8. A stitching machine according to claim 7, further comprising conterweights connected to the cross bridge for off-setting the gravity bias of the cross bridge, and the platforms, sewing machine components, and drive means carried thereon, during vertical cross bridge movement along the vertical side columns.

9. A stitching machine according to claim 7, further comprising a conveyor having a vertical run aligned between the spaced vertical side columns and extended between the front and rear beams of the cross bridge, the conveyor having means thereon to releasibly retain the leading edge of the flexible sheets to be seamed and to move said leading edge to near the upper end of said vertical run and there by have the remainder of the sheets suspended vertically therebelow along the conveyor run and between the sewing machine components, and said leading edge retaining means being part of said means holding the peripheral edges of the flexible sheets.

10. A stitching machine according to claim 9, further comprising the conveyor being an endless loop having a substantially uniform width greater than the width of the flexible sheet(s) to be stitched and having a length at least twice the height of the vertical run and defining in addition co the vertical run a second run not passing between the cooperating sewing machine components, and the conveyor having separate means thereon to releasibly retain the leading edges of different sets of the sheet(s) respectively at the vertical and second runs, whereby one set of flexible sheet(s) can be at the vertical run for being stitched while another set of flexible sheet(e) can simultaneously be at the second run for being retained on or removed from the conveyor.

11. A stitching machine according to claim 9, further comprising the conveyer being an endless loop having a substantially uniform width greater than the width of the flexible sheet(s) to be stitched and having a length slightly exceeding three times the height of the vertical run, and the conveyor having at substantially equal spacings around the loop separate means thereon to releasibly retain the respective leading edges of three sets of the sheet(e) simultaneously at substantially equal spacinge around the loop, whereby the different sets of flexible sheet(s) can be respectively, being stitched, being retained on or removed from the conveyor, or waiting for being stitched or being removed.

12. A stitching machine according to claim 11, further comprising the conveyor endless loop being proportioned so that the positions of the separate means on the conveyor to releasibly retain the leading edge of the sheet (s), after each indexing of the conveyor loop, will be positioned respectively at a stitching position near the upper end of the vertical run, at a pre-stitching position near the lower end of the vertical run, and at an accessible comfortable height position spaced above the floor for retaining/removing the flexible sheet(s) relative to the conveyor.

13. A stitching machine according to claim 12, further comprising counterweights connected to the cross bridge for off setting the gravity bias of the cross bridge, and the platforms, sewing machine components, and drive means carried thereon, during vertical cross bridge movement along the vertical side columns.