US3778050A

US3778050A - Auxiliary fabric feed means for fabric spreading machine

Info

Publication number: US3778050A
Application number: US00190564A
Authority: US
Inventors: H Grimm; I Zuckerman
Original assignee: Panther Machine Corp
Current assignee: Panther Machine Corp
Priority date: 1971-10-19
Filing date: 1971-10-19
Publication date: 1973-12-11
Anticipated expiration: 1990-12-11

Abstract

In a fabric spreading machine in which fabric is fed from a supply roll over a positive feed roller and then to fold-forming bars upon which a catcher bar falls to form a fold about the fold-forming bar and carry the fold to the table surface, means are provided for providing additional slack in the fabric as the catcher bar engages and presses down the fold on the fold-forming bar. The slack providing means includes a solenoid-operated linkage operative to move a tension-providing guide roller away from the positive feed roller to permit the fabric to hang loosely from the latter.

Description

lited States Patent 1 1 Grimm et al.

[451 Dec. 11, 1973 AUXILIARY FABRIC FEED MEANS FOR FABRIC SPREADING MACHINE [73] Assignee: Panther Machine Corp., New York,

[22] Filed: Oct. 19, 1971 211 Appl. No.: 190,564

[52] U.S. Cl. 270/31 [51] Int. Cl B65h 29/46 [58] Field of Search 270/30, 31

[56] References Cited UNITED STATES PATENTS 3,540,720 11/1970 Merrill et al 270/31 2,921,786 H1960 Deichmann et al 270/31 1l/1963 Theodosiou 270/31 2/1972 Grimm et a1 270/31 Primary Examiner-Robert W. Michell Assistant Examiner-L. R. Oremland Attorney-Edward F. Levy {57] ABSTRACT In a fabric spreading machine in which fabric is fed from a supply roll over a positive feed roller and then to fold-forming bars upon which a catcher bar falls to form a fold about the fold-forming bar and carry the fold to the table surface, means are provided for providing additional slack in the fabric as the catcher bar engages and presses down the fold on the fold-forming bar. The slack providing means includes a solenoidoperated linkage operative to move a tensionproviding guide roller away from the positive feed rollet to permit the fabric to hang loosely from the latter.

8 Claims, 4 Drawing Figures t a a 44 efi f gg m iiii PATENI BEm z 1225 SHEETIUFZ m N m mmm ifm WNR T mu a PAIENIEU I sumznrz INVENTOR HAROLD 6 MM M B lRA ZUCKERMAN ATTORNEY AUXILIARY FABRIC FEED MEANS FOR FABRIC SPREADING MACHINE The present invention relates to devices for spreading sheet material such as fabric in uniform superimposed layers upon a table surface, and in particular to a fabric spreading machine in which a friction roller is employed to impart a positive drive to the fabric being fed through the machine.

In conventional automatic fabric spreading machines, a supply of fabric, usually in roll form, is mounted upon a carriage and fed therethrough t the surface of a table. The carriage moves back and forth along the table while layers of the fabric are spread on the table surface, one upon the other. The carriage is provided with fold-forming blades or bars around which the fabric is guided so as to form a fold at the end of a layer of sheet material as the carriage reaches the end of its travel in each direction and begins to move back in the opposite direction. The fold-forming blades cooperate with fold-retaining devices or catchers located at each end of the table, each catcher engaging the fold of fabric on the respective blade and clamping it on the table surface as the carriage moves away toward the opposite catcher.

As the catcher engages the fabric and clamps it flat upon the fold-forming blade to retain the fold thereon, it must draw extra fabric to bring it flat upon the top of the blade. This presents no problem in the usual automatic spreading machine where the fabric is guided freely from the mounted roll to the form-folding blade, the freely mounted roll supplying the extra fabric or slack when needed.

In some spreading machines, however, the fabric is not guided freely to the table surface, but rather a positive drive friction roller is provided about which the fabric is trained as it leaves the supply roll. The positive feed roller is driven in response to movement of the carriage back and forth over the table, so as to draw the fabric from the supply roll and feed it to the surface of the table. The positive feedroller is provided with a serrated or rough surface so as to grip the fabric trained thereabout. v

Conventionally, positive feed rollers have been used in turntable type spreading machines or other machines in which the fabric is not laid down in folds andno automatic catcher mechanism is employed. Rather, the fabric is laid down in individual, superimposed layers, each layer being cut off at both ends. Recently, however, it has been found desirable to include a positive drive roller in the automatic spreading machines of the type which include fold-forming blades and catchers to clamp down the folds at the end of the spread fabric. Such use of a positive feed roller is advantageous in the spreading of knit goods and other stretchable fabrics since it produces a controlled feed of the fabric which prevents undesirable stretching thereof.

The use of a positive feed roller in a spreading machine having fold-forming blades and catchers presents an inherent problem. Since slack in the fed fabric is required to permit the catcher to clamp the fold upon the fold-forming blade and bring it to the table surface, and since the fed fabric is gripped frictionally by the positive feed roller about which it is entrained, the catcher cannot draw excess fabric from the supply roll. Consequently, the excess fabric must be drawn from the layer being spread upon the table and gripped by the catcher at the other end of the table. This causes stretching of the spread layer and tensioning of the same, so that when the spread fabric is cut to pattern shapes, it tends to shrink in unpredictable amounts.

It is the principal object of the present invention to provide in a cloth spreading machine having a positive feed roller, fold-forming blades and fold-retaining catchers, auxiliary fabric feed means for providing additional slack in the fabric being fed from the positive feed roller to the fold-forming blades at each end position during the travel of the carriage as the catcher structure clamps the fold upon the form-folding blade and brings the fold to the table surface.

Another object of the invention is the provision of auxiliary fabric feed means of the character described in which a roller normally holds the fabric wrapped around the positive feed roller, the roller being movable away from the positive feed roller to provide additional slack in the fabric fed to the fold-forming blades, in response to movement of the carriage to its end positions in which the catcher engages said blades.

A further object of the invention is the provision of auxiliary fabric feed means of the character described which is of simple construction and includes few parts, so that it may be economically manufactured and readily incorporated in spreading machines.

In accordance with the invention herein, there is provided auxiliary fabric feed means in a fabric spreading machine having a positive drive roller which feeds fabric between a pair of movable fold-forming members. The auxiliary feed means comprises an idler roller mounted by movable support means in a normal operative position adjacent the surface of the positive drive roller to hold a bight of fabric around the surface of the latter, and movable to an inoperative position in which it is remote from the positive drive roller and permits the fabric to hang freely from the positive drive roller to the fold-forming members. The idler roller is moved to its inoperative position in response to movement of one of the fold-forming members and and just before a fold-retaining bar drops upon the other fold-forming member to form and grip a fold thereon. Cam means on the moving fold-forming bar actuates a micro-switch which energizes a solenoid connected by a linkage to the idler roller for moving the idler roller to its inoperative position and supplying additional slack fabric to the fold-forming member on which the fold retaining bar falls.

Additional objects and advantages of the invention will become apparent during the course of the following specification when taken in connection with the accompanying drawings, in which:

FIG. 1 is a side elevational viewof a fabric spreading machine made in accordance with the present invention, with a portion of the side frame broken away to reveal inner constructional details;

FIG. 2 is a partial side elevational view of the machine in the position shown in FIG. 1, illustrating the auxiliary fabric feed means of the present invention;

FIG. 3 is a partial side elevational view of the machine similar to FIG. 2, but showing the machine in a more advanced location along its travel, and the auxiliary fabric feed means in its operative position; and

FIG. 4 is an enlarged partial view of the linkage portion of the auxiliary fabric feed means.

Referring in detail to the drawings, there is shown a fabric spreading machine incorporating the auxiliary fabric feed means of the 'invention. The machine includes a carriage 10, having a pair of

upright side frames

12 and 14 connected in spaced relationship by cross bars 16. Each of the frames is mounted on a pair of wheels 18, the wheels at one side of the machine being flanged and riding on a rail (not shown) mounted on the support table 20.

Mounted on the carriage is a frame 22, which may be of the turntable type, said frame 22 mounting a pair ofspaced uprights 24 between which a roll of fabric 26 may be rotatably mounted. The fabric 28, in sheet form, is fed from the roll 26 and through carriage 10 to the surface of table 20, where it is laid down in a uniform stack of folded sheets as the carriage is rolled back and forth along the table.

For purposes of drawing the fabric 26 at a uniform rate from the roll 26 during movement of the carriage, a positive drive roller 30 is mounted on a shaft 32 between the

frames

12 and 14 and is coupled by connecting means (not shown) to one of the wheels of carriage 10 in such a manner that rotation of the wheel, as the carriage rolls along the table, causes corresponding rotation of the roller 30. Also associated with the roller 30 is a one-way clutch mechanism of conventional construction which functions to cause the roller 30 to rotate in a clockwise direction, regardless of the direction of travel of the carriage 10.

The roller 30 has an outer circumferential surface which is abraded or knurled to grip the fabric material 28 passing thereover. In order to provide the necessary gripping action, it is ncessary for the fabric to extend about a substantial portion of the circumference of roller 30. For this purpose, an idler roller 34 is mounted between the

frames

12 and 14 and is located in close proximity to the rear surface of roller 30. In addition, a second idler roller 36 is movably mounted between the frames, in a manner to be presently described, and is normally located in a position below and to the rear of the positive drive roller 30 so as to maintain the fabric 28 in firm engagement with a major surface portion of roller 30, as shown in FIG. 1.

The carriage 10 also includes fold-forming means in the nature of a pair of fold-forming

bars

40 and 42 which extend transversely across the carriage 10. The

bars

40 and 42 are mounted on respective arms or

links

44 and 46 which are mounted by

pivot pins

48 and 50 on an extension 51 of carriage 10. The

links

44 and 46 may thus turn about their pivot pins to swing the

respective bars

40 and 42 toward each other, in a manner to be presently described. This fold forming means is illustrated and described in detail in our US. Pat. No. 3,473,798 granted Oct. 21, 1969 and assigned to the same assignee as the instant application, and reference is made thereto for further disclosure.

The fabric spreading machine also includes a pair of fold-retaining members or catchers 52 and 54 of conventional construction, which are mounted on opposite ends of the table 20. As is well known, these foldretaining members 52 and 54 each have a pair of spaced arms 56 situated adjacent the side edges of the table and connected at their free ends by a foldengaging and retaining bar 58 which extends transversely across the table. The arms 56 are movably mounted on a frame for raising and lowering the retaining bar 58 in a vertical direction, in a well-known manner, and the arms 56 carry at their outer surfaces rollers 60 which function to raise the arms in a manner to be p described. The catchers 52 and 54 may be of the type described and illustrated in our US. Pat. No. 3,497,204 granted Feb. 24, 1970 and assigned to the same assignee as the instant application.

Pivotally mounted on the frame extensions 51 are pairs of camming

arms

62 and 64 whose upper edges are to be engaged by the rollers 60 on the fold-retaining members 52 and 54. At the regions of the upper ends of the camming

arms

62 and 64 the frame extensions 51 fixedly carry at their inner surfaces horizontal platforms 66 and 68. These platforms 66 and 68 act as continuations of the

respective camming arms

62 and 64 and serve as tracks upon which the rollers 60 ride after the camming arms have elevated the rollers 60.

It will be seen in FIG. 1 that the fabric 28 drawn from roll 26 passes around positive drive roller 30, being held firmly thereagainst by the

idler rollers

34 and 36, the fabric then passing about the idler roller 36 and extending downwardly at a slight forward angle and passing between the fold-forming

bars

40 and 42.

Assuming now that the carriage 10 is advancing to the left, as indicated by the arrow 70 in FIG. 1, while the fold-retaining member 54 retains the fold at the right end of the layer 72 which is being spread during this movement of the carriage 10, it will be seen that the carriage is approaching the fold-retaining member 52. At this time, both

links

44 and 46 are in their vertical operative positions, and the bar 40 leads the bar 42, while the sheet material 28 is guided around the trailing bar 42 during spreading of the layer 72.

As the carriage approaches the end of its travel to the left, as viewed in FIG. 1, the rollers 60 of the foldretaining means 52 engage the left camming arms 62 and ride along the upper surfaces thereof as these arms 62 travel to the left along with the entire carriage 10. In this manner, the rollers 60 elevate the arms 56 and the retaining bar 58 of the fold-retaining means 52. FIG. 1 shows the rollers 60 approaching the upper end of the camming arms 62 as the carriage 10 moves into engagement with the fold-retaining means 52.

Further movement of the carriage 10 to the left brings the leading fold-forming member into engagement with the fold-retaining member 52, and a portion of the arm 56 engages the link 44, causing it and the fold-forming bar 40 to swing upwardly to a horizontal position, as shown in FIG. 3, to permit passage of the fold-retaining bar 58.

When the rollers 60 reach the upper ends of the camming arms 62, they move along the horizontal platforms 66, and then fall off the ends of these platforms as the carriage l0 continues to advance and approaches the end of its stroke. The fold-forming bar 58 now simply falls onto the trailing fold-forming bar 42 with the fabric 28 engaged between the

bars

42 and 58, in the manner shown in FIG. 3. The carriage 10 has now completed its movement to the left and is ready to reverse its direction of movement and commence travel to the right, then toward fold-retaining member 54, at which time the fold-retaining bar 58 carries the fold from the fold-forming bar 42 and deposits it upon the stack of layers already spread upon the table 20.

The above-described operation is conventional and is described in detail in our aforementioned US. Pat. No. 3,473,798. It will be appreciated that when the foldretaining bar 58 falls upon the fold-forming bar 42 to clamp the formed fold upon the bar 42, approximately 1% inches of extra fabric is required to permit the fold to be formed and then carried to the table. In conventional spreading machines, where the fabric feeds directly from the freely mounted roll 26 to the foldformin'g bar 42, this extra fabric is drawn easily from the feed roll 26, and no problem is presented. Where, however, a positive feed roller is provided in the machine, as shown herein, the fed fabric is firmly wrapped around the frictional surface of the positive feed roller 30, and the required extra fabric cannot be drawn therefrom. Consequently, the extra fabric for forming the fold can only be obtained by stretching the fabric feeding between the roller 36 and the fold-forming bar 42, as well as the layer of fabric 72 extending between the bar 72 and the fold-retaining bar 58 of the catcher 54. As previously described, this tensions the spread material, and causes undesirable stretching thereof.

The fabric spreading machine, in accordance with the invention herein, is provided with fabric releasing means 80 which is effective automatically to supply the required slack in the fed fabric at the time that the foldretaining bar 58 of either catcher 52 or 54 drops upon its respective fold-forming bar. The fabric releasing means 80 includes a lever 82 mounted at its center by pivot 84 on the outer surface of side frame 14, and having an upper arm connected by pivot 86 to one end of a link 88. The other end of link 88 is connected by pivot 90 to a triangular link 92 which is mounted on a rod 94 extending through and journalled in the frame 14. Secured to the other end of the rod 94 is an angular arm 96, on the free end of which is mounted the idler roller 36. It will thus be seen that when the triangular link 92 is turned, it rotates the rod 94 and causes the angular arm 96 and idler roller 36 to turn correspondingly.

The lower arm of lever 82 is connected by a coil spring 98 to the plunger 100 of a solenoid 102 mounted on the side frame 14. The solenoid 102 is energized by the upward swinging movement of either of the foldforming bars 40 or 42, in the manner shown in FIGS. 2 and 3. For this purpose, the

arms

44 and 46 carrying the fold-forming

bars

40, 42 and located adjacent the frame 14, are each provided with a top circular cam surface 104 which terminates in a depressed notch 106. Associated with the

respective arms

44 and 46 are a pair of micro-switches 108 and 110. Each micro-switch has an arm 112 terminating in a roller 114. The microswitches 108 and 110 are mounted on the side frame 14 with the micro-switch arms 112 normally biased outwardly so that the rollers 114 seat in the notches 106 of the

arms

44 and 46 which are in the depending position shown in FIG. 2. In the outwardly biased position of the arms 112, the micro-switches 108 and 110 are open.

Both of the micro-switches 108 and 110 are electrically connectedby respective leads 116 and 118 to the solenoid 102, with the micro-switches interposed between the solenoid 102 and a source of electrical power (not shown) in such a manner that when either

microswitch

116 or 118 is closed, the solenoid 102 will be energized.

As the carriage is moving along the table and spreading a layer 72 of fabric thereon, as shown in FIGS. 1 and 2, the lever 82 and

links

88 and 92 are in the positions shown in FIG. 2, with the arm 96 disposed in a rearwardly inclined position in which it holds the idler roller 36 close to the rear surface of the positive drive roller 30. The fabric 28 is thus drawn around the under surface of the positive drive roller 30 and then passes around idler roller 36, extending from the latter in a downward and slightly forward direction to the pointat which it passes between the fold-forming

bars

40 and 42. The

arms

44 and 46 of the fold-forming bars are depending vertically and the rollers 114 of the micro-switch arms 112 are located in the notches 106 of the

arms

44 and 46 so that both micro-switch arms 112 are extended, the micro-switches 108 and 110 are open, and the solenoid 102 is deenergized. The solenoid plunger 100 is extended, as shown in FIG. 2, and no tension is exerted upon spring 98.

As the carriage 10 moves further to the left, and further into engagement with the fold-forming member 52, the roller 'reaches the top of camming arm 62 and travels on to the platform 66, the catcher arm 56 engages the arm 44 and turns it to the horizontal position shown in FIG. 3. As the arm 44 rotates, the arcuate cam surface 104 moves into engagement with roller 114, thereby depressing arm 112 of micro-switch 108, closing the latter and energizing solenoid 102.

, Energization of solenoid 102 draws the plunger inwardly as shown in FIG. 3, tensioning coil spring 98 and causing lever 82 to turn in a counter-clockwise direction about pivot 84. Lever 82 moves link 88 in a forward direction, the latter turning triangular link 92 in a clockwise direction and thus turning rod 94 and angular arm 96 in the same direction. Arm 96 turns down to the vertical position shown in FIG. 3, bringing the idler roller 36 to a position spaced below and vertically aligned with the forward surface of the positive drive roller 30, just before the fold-engaging bar 58 falls upon the fold-forming bar 42. This movement of the idler roller 36 releases approximately 1% inches of slack in the fed fabric 28 and permits the fabric to hang freely between the positive drive roller 30 and the foldforming bar 42. Thus,-when the fold-retaining bar 58 falls upon the fold-forming bar 42, this extra slack in the fabric enables a fold to be formed on the foldforming bar 42 and held flat thereon by the foldretaining bar 58, without tensioning or stretching the fabric material.

The direction of travel of the carriage 10 is now reversed, and the carriage moved toward the right, as viewed in FIG. 3. As this movement commences, the fold of fabric is gripped by the fold-retaining bar 58 and drawn off the fold-forming bar 42, being then deposited on the table. At the same time, the arm 44 moves out of engagement with the catcher arm 56 and is allowed to drop to its vertical, depending position. The notch 106 on the arm 44 then moves into registry with the roller 114 and permits the micro-switch arm 112 to move outwardly to extended position, opening micro-switch 108 and de-energizing the solenoid 102. A spring 120, connecting the triangular link 92 to the side frame 14, is then effective to turn link 92 back to its original position of FIG. 2, and the connecting linkage brings the solenoid plunger 100 back to its extended position.

As the carriage 10 completes its movement to the right, the arm 46 engages the opposite fold retaining member 54 and is raised thereby to a horizontal osition so that it closes micro-switch in the same manner, and energizes solenoid 102 to again release slack in the fed fabric. The operation is thus repeated each time that the carriage approaches the end of its travel in either direction along the table 20.

While a preferred embodiment of the invention has been shown and described herein, it is obvious that numerous omissions, changes and additions may be made in such embodiment without departing from the spirit and scope of the invention,

What is claimed is:

1. In a fabric spreading machine including a carriage which moves back and forth over a table surface in opposed operative strokes between a pair of foldretaining members, a pair of fold-forming members movably mounted on the carriage and normally disposed in an operative, fold-forming position, a positive drive roller mounted on the carriage and operative to draw fabric from a supply carried by the carriage and feed the fabric between said fold-forming members to the table surface, said fold-retaining members being located in the path of movement of the fold-forming members and positioned to engage the leading foldforming member and move it out of its operative position to a displaced position as the carriage approaches the end of an operative stroke, thereby providing clearance to the fold-retaining member to engage the trailing fold-forming member and form a fold of fabric thereon, the improvement comprising auxiliary feeding means for supplying additional slack fabric to said trailing fold-forming member as the fold-retaining member moves into engagement therewith, said auxiliary feeding means comprising an idler roller, support means movably mounting said idler roller on said carriage for movement between an operative position in which the idler roller is closely spaced from the surface of said positive drive roller and holds bight of fabric thereabout, and a release position in which said idler roller is remote from said positive drive roller and frees said fabric to hang directly down from the positive drive roller to the trailing fold-retaining member, a solenoid, means operatively connecting said solenoid to said idler roller support means for moving the idler roller to its release position when said solenoid is energized and returning said idler roller to its operative position when said solenoid is deenergized, switch switch means connecting said solenoid to an electrical power source, and cam means on said fold retaining members in engagement with said switch means for actuating the latter when either of said fold-forming members is moved to its displaced position.

2. Auxiliary feeding means according to claim 1 in which said idler roller support means comprises an arm carrying said idler roller, a lever mounted on said carriage, a linkage connecting said lever to said arm for turning the latter when said lever is turned, and coupling means connecting said solenoid to said lever.

3. Auxiliary feeding means according to claim 2 in which said solenoid has a plunger which is drawn inwardly when said solenoid is actuated, and in which said coupling means comprises a coil spring connecting said solenoid plunger to said lever.

4. Auxiliary feeding means according to claim 2 in which said linkage includes a triangular link, a rod secured at one end to a corner of said triangular link and at the other end to said arm for simultaneous rotation of said triangular link and said arm, and a link connecting a second corner of said triangular link to said lever.

5. Auxiliary feeding means according to claim 4 which also includes a return spring connected at one end to the carriage and at its other end to the third corner of the traingular link.

6. Auxiliary feeding means according to claim 1 in which said fold-forming members comprise a pair of fold-forming bars, each having a pair of support arms swingably mounted on the carriage, said support arms having cam surfaces in engagement with said switch means.

7. Auxiliary feeding means according to claim 6 in which said switch means includes a pair of microswitches each having a movable switch arm in engagement with the cam surfaces of the respective support arms.

8. Auxiliary feeding means according to claim 6 in which said fold-forming members have normal depending positions in which the fold-forming bars are horizontally disposed at the same elevation, and in which the fold-retaining member, toward which the carriage is moving in its operative stroke, engages the leading fold-forming member and turns it to an elevated position immediately in advance of the fold-retaining member engaging the trailing fold-forming member to form a fold thereon, the cam surface on said leading foldforming member being arranged to activate said switch means andmove said idler roller to its release position immediately upon movement of said leading foldforming member to its elevated position.

Claims

1. In a fabric spreading machine including a carriage which moves back and forth over a table surface in opposed operative strokes between a pair of fold-retaining members, a pair of foldforming members movably mounted on the carriage and normally disposed in an operative, fold-forming position, a positive drive roller mounted on the carriage and operative to draw fabric from a supply carried by the carriage and feed the fabric between said fold-forming members to the table surface, said fold-retaining members being located in the path of movement of the fold-forming members and positioned to engage the leading fold-forming member and move it out of its operative position to a displaced position as the carriage approaches the end of an operative stroke, thereby providing clearance to the fold-retaining member to engage the trailing fold-forming member and form a fold of fabric thereon, the improvement comprising auxiliary feeding means for supplying additional slack fabric to said trailing fold-forming member as the fold-retaining member moves into engagement therewith, said auxiliary feeding means comprising an idler roller, support means movably mounting said idler roller on said carriage for movement between an operative position in which the idler roller is closely spaced from the surface of said positive drive roller and holds bight of fabric thereabout, and a release position in which said idler roller is remote from said positive drive roller and frees said fabric to hang directly down from the positive drive roller to the trailing fold-retaining member, a solenoid, means operativEly connecting said solenoid to said idler roller support means for moving the idler roller to its release position when said solenoid is energized and returning said idler roller to its operative position when said solenoid is deenergized, switch switch means connecting said solenoid to an electrical power source, and cam means on said fold retaining members in engagement with said switch means for actuating the latter when either of said fold-forming members is moved to its displaced position.

7. Auxiliary feeding means according to claim 6 in which said switch means includes a pair of micro-switches each having a movable switch arm in engagement with the cam surfaces of the respective support arms.

8. Auxiliary feeding means according to claim 6 in which said fold-forming members have normal depending positions in which the fold-forming bars are horizontally disposed at the same elevation, and in which the fold-retaining member, toward which the carriage is moving in its operative stroke, engages the leading fold-forming member and turns it to an elevated position immediately in advance of the fold-retaining member engaging the trailing fold-forming member to form a fold thereon, the cam surface on said leading fold-forming member being arranged to activate said switch means andmove said idler roller to its release position immediately upon movement of said leading fold-forming member to its elevated position.