[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S.

Provisional Application Serial No. 62/573,949 filed on October 18, 2017, the content of which is relied upon and incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present invention relates to a glass sheet packing system for accumulating thin glass sheets on a crate, and more particularly to a glass sheet packing system for alternately accumulating glass sheets and sheets of interleaf paper in a standing position.

BACKGROUND ART

[0003] Conventionally, glass sheet packing systems for alternately accumulating glass sheets and sheets of interleaf paper in a standing position on a crate are known, as taught in Japanese Unexamined Patent Publication No. 2006-056675 (hereinafter, Patent Literature 1), for example. Patent Literature 1 also teaches that a sheet of interleaf paper is formed by cutting a web when the glass sheets are accumulated on the crate, as described above.

SUMMARY

[0004] However, with conventional glass sheet packing systems, where a web is cut to form a sheet of interleaf paper and glass sheets and sheets of interleaf paper are alternately accumulated on a crate in a standing position, there still is a need for improvement in reducing the time for the process from the cutting of the web to the placement of the glass sheet.

[0005] In view of the above-described circumstances, the present disclosure describes a glass sheet packing system that allows reducing the time to complete the process from the cutting of the web to the placement of the glass sheet.

[0006] An aspect of the glass sheet packing system is a glass sheet packing system for alternately accumulating glass sheets and sheets of interleaf paper in a standing position on a glass sheet placing surface of a crate, the packing system comprising 1) a glass sheet feeding apparatus and 2) an interleaf feeding apparatus, as described below. [0007] Namely, 1) the glass sheet feeding apparatus forming the glass sheet packing system comprises: a. a set of suction cups configured to hold each of glass sheets, which are successively conveyed thereto in the vertical orientation, and release the glass sheet after the glass sheet is placed on the glass placing surface; and b. a first robot arm comprising the suction cups fixed thereto and configured to feed the glass sheet held by the suction cups onto the glass sheet placing surface.

[0008] Further, 2) the interleaf feeding apparatus forming the glass sheet packing system comprises: a. 2-1) a roll shaft configured to hold a web of the interleaf paper wound thereon; b. 2-2) a web spreading unit configured to spread the web by unwinding the web from a leading end side thereof; c. 2-3) a web guide configured to guide the unwound web such that the leading end of the unwound web moves down from above the glass sheet placing surface to allow the web to face the glass sheet placing surface; d. 2-4) a web pull down unit which comprises a pair of clampers configured to hold and release parts in the vicinity of the leading end of the web, and an elevator configured to move the clampers up and down along the glass sheet placing surface, wherein the elevator moves downward to move the clampers holding the web downward to pull down the web during a first period of time and a second period of time with a rest period of time interposed therebetween; e. 2-5) a cutter configured to cut the web at a predetermined distance from the leading end of the web to form a sheet of interleaf paper during the rest period of time, when the web pulled down during the first period of time is in a position to face the glass sheet placing surface; f. 2-6) an interleaf paper transfer unit which comprises a suction holder configured to hold and release the interleaf paper, and a second robot arm configured to move the suction holder, wherein the suction holder holds a part in the vicinity of the trailing end of the interleaf paper during the rest period of time and the second robot moves the suction holder downward in synchronization with the downward movement of the elevator during the second period of time whereby to transfer the interleaf paper to a predetermined position of height where the interleaf paper faces the glass sheet placing surface, and to release the interleaf paper from the suction of the suction holder after one glass sheet is fed onto the transferred interleaf paper by the glass sheet feeding apparatus; and g. 2-7) a web fixing unit configured to hold the web at a fixed position during the rest period of time from before the web is cut by the cutter until the interleaf paper is held by the suction holder of the interleaf paper transfer unit.

[0009] It is desirable that the web fixing unit comprise a suction bar comprising a suction surface extending in the direction of width of the web fed thereto and configured to suck and fix the surface of the web facing the glass sheet placing surface.

[00010] It is more desirable that the suction bar be movable between a retracted position where the suction surface thereof is apart from the web when the suction bar does not suck and fix the web and a sucking position where the suction surface thereof is in contact with the web when the suction bar sucks and fixes the web.

[00011] In the case where the web fixing unit comprises the suction bar as described above, it is desirable that the suction holder of the interleaf paper transfer unit suck and hold a part in the vicinity of the trailing end of the interleaf paper fixed on the suction surface of the suction bar. In the case where the web fixing unit comprises the suction bar as described above, and the suction bar is movable between the retracted position and the sucking position, it is desirable that the suction holder of the interleaf paper transfer unit suck and hold a part in the vicinity of the trailing end of the interleaf paper fixed on the suction surface of the suction bar.

[00012] It is desirable that, in the glass sheet packing system, the suction holder of the interleaf paper transfer unit also serve as the web fixing unit.

[00013] It is desirable that, in the glass sheet packing system, the feeding velocity of the web of the web pull down unit be higher than that of the web spreading unit, and a dancer roller which is movable to slack the web and absorb the slack be provided in a web feeding path between the web spreading unit and the web pull down unit. [00014] It is desirable that the suction holder of the interleaf paper transfer unit comprise a suction surface extending across the width of the web, for example the entire width of the web.

[00015] It is desirable that the glass sheet feeding apparatus be configured to feed the glass sheets successively conveyed thereto in a vertical orientation onto the glass sheet placing surface along a minimum path from a position where each glass sheet to be fed is stopped in a path of the conveyance.

[00016] It is desirable that the second robot arm perform the downward movement of the suction holder synchronized with the downward movement of the elevator without tensioning the interleaf paper.

[00017] It is desirable that the cutter comprise a cutting blade extending across the web, for example the entire width of the web, and cuts the web by moving the cutting blade in a direction of the thickness of the web.

[00018] It is desirable that the glass sheet placing surface of the crate be inclined to face slightly upward.

[00019] In the glass sheet packing system, a sheet of interleaf paper formed by cutting the web is transferred from the clampers, which form the web pull down unit, to the suction holder, which forms the interleaf paper transfer unit together with the robot arm, in the course of moving the sheet of interleaf paper to the lowermost position to place the interleaf paper on the crate. To feed the interleaf paper onto the glass sheet placing surface of the crate, the robot arm, which is relatively incapable of high speed operation but is capable of high precision operation, is used to transfer the interleaf paper. On the other hand, to pull down the web before the transfer, the elevator blocks and the clampers, which are capable of high speed operation, are used. Increasing the speed of pulling down of the web in this manner allows reducing the time to complete the process from the cutting of the web to the placement of the glass sheet.

[00020] Further, transferring the sheet of interleaf paper from the clampers to the suction holder allows the elevator blocks, which form the web pull down unit, to return to the uppermost position to begin the next pulling down of the web before the sheet of interleaf paper reaches the lowermost position, i.e., before one glass sheet is placed on the sheet of interleaf paper. This feature of the glass sheet packing system of this embodiment also contributes to reducing the time to complete the process from the cutting of the web to the placement of the glass sheet.

BRIEF DESCRIPTION OF THE DRAWINGS

[00021] FIG. 1 is a schematic side view illustrating a glass sheet packing system according to exemplary embodiments, a. FIG. 2 is a schematic perspective view illustrating the glass sheet packing system, b. FIG. 3 is a schematic side view illustrating a web fixing unit of the glass sheet packing system, c. FIG. 4 is a schematic perspective view illustrating a web pull down unit of the glass sheet packing system, d. FIG. 5 is a schematic diagram illustrating timing of operations of the web pull down unit and the web spreading unit of the glass sheet packing system, and e. FIG. 6 is a schematic side view illustrating the web fixing unit of FIG. 3 in a different state.

DESCRIPTION OF EMBODIMENTS

[00022] Reference will now be made in detail to exemplary embodiments of the disclosure, which will be described with reference to the drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. However, this disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. FIGs. 1 and 2 are a side view and a perspective view, respectively, illustrating a glass sheet packing system 1 according to exemplary embodiments. As shown in these drawings, the system 1 is configured to alternately accumulate glass sheets G, which are successively conveyed thereto one by one by a glass sheet conveying unit 10, and sheets of interleaf paper 5 on a crate 6. As shown in FIGs. 1 and 2, system 1 comprises a glass sheet feeding apparatus 20 and an interleaf feeding apparatus 40.

[00023] The glass sheet conveying unit 10 is configured to convey the glass sheets G to a position near the glass sheet feeding apparatus 20, and includes a rail 11, dollies 12 suspended from and run along the rail 11, and a holder 13 attached to each dolly 12 to hold a single glass sheet G. The rail 11 extends along a circular path to run from a glass sheet manufacturing section (not shown), through the vicinity of the glass sheet feeding apparatus 20, and back to the glass sheet manufacturing section. Each of the dollies 12 is suspended from the circular rail 11. At the glass sheet manufacturing section, the holder 13 of each dolly 12 holds a single glass sheet G in a standing position. Then, the dollies 12, each holding a single glass sheet G, run along the rail 11 and successively arrive at the vicinity of the glass sheet feeding apparatus 20. Each dolly 12 having conveyed the glass sheet G to a position to face the glass sheet feeding apparatus 20 is temporarily stopped at the position.

[00024] A crate 6 is placed in the vicinity of the glass sheet feeding apparatus 20. The crate 6 includes a glass sheet placing surface 6a, on which the glass sheets G are placed, a bottom plate 6b for supporting the glass sheets G placed thereon from below, and a mount 6c, which is placed on a floor surface 100. The glass sheet placing surface 6a is disposed such that it is inclined relative to the vertical direction to face slightly upward when the crate 6 is erected. Further, the position where the crate 6 is placed (crate set position) is determined such that the center in the horizontal direction of the glass sheet placing surface 6a is aligned with the center in the horizontal direction of the glass sheet G held by the temporarily stopped dolly 12.

[00025] The glass sheets G and the sheets of interleaf paper 5 are accumulated on the crate 6, as described later, and when the accumulating operation is completed, the crate 6 is removed from the crate set position, and another empty crate 6 is fed into the crate set position. The feeding and removal of the crate 6 into and from the crate set position is achieved by moving the crate 6 on the floor surface 100 in the direction of arrow Q (±Q -direction) shown in FIG. 2, such that the crate does not interfere with the interleaf feeding apparatus 40, features of which will be described later. The Q-direction is a direction that obliquely crosses a conveyance direction X of the glass sheets G in the horizontal plane.

[00026] It should be noted that the process of accumulating the glass sheets G together with the sheets of interleaf paper 5 on the crate 6 is applicable to situations where the glass sheets G are shipped as final products in that state, or the glass sheets G are transferred for further processing. This process may also be applied to situations where the glass sheets G are successively conveyed to the site of a certain glass processing operation by the glass sheet conveying unit 10 when the glass processing operation is temporarily unavailable, for example, the conveyed glass sheets G may be carried and temporarily accumulated out of the processing line.

[00027] The glass sheet feeding apparatus 20 includes a glass sheet holding frame 21, a plurality of suction nozzles 22 held by the glass sheet holding frame 21, and a glass sheet feeding robot 23, such as a six- axis articulated robot. A robot arm 24 of the glass sheet feeding robot 23 is coupled to the glass sheet holding frame 21. It should be noted that the robot arm 24 forms the first robot arm of the disclosure.

[00028] The suction nozzles 22 can be arranged in rows and columns. Each suction nozzle 22 can be in fluid communication with a common suction source (not shown) via a control valve. When the control valve is open and the suction nozzles 22 suck air, the suction nozzles 22, i.e., the glass sheet holding frame 21, can hold a single glass sheet G by suction. From this state, when the control valve is closed to stop suction by the suction nozzles 22, the glass sheet G is released from the suction of the suction nozzles 22 and released from the glass sheet holding frame 21. The suction nozzles 22 may be made of a soft material, such as rubber, so as not to damage the glass sheets G, and can have a shape which is generally referred to as "suction cup".

[00029] Referring again to FIGs. 1 and 2, the interleaf feeding apparatus 40 includes: a roll shaft 41 configured to hold a web 5W, which is the material of the interleaf paper 5, wound thereon; a roll shaft driving means 42 configured to rotate the roll shaft 41 in a direction in which the web 5W is unwound; guide rollers 43 to 48 around which the unwound web 5W is wrapped; a dancer roller 49 around which the unwound web 5W is wrapped between the guide rollers 43 and 44; a guide 50 configured to guide the leading end of the web 5W; a cutter 51 configured to cut the web 5W passed through the guide 50; a pair of guide bars 60; clampers 62, each configured to run along the corresponding guide bar 60; an interleaf paper transfer robot 63, such as a six-axis articulated robot, having a robot arm 72; and a suction bar 64 serving as the web fixing unit.

[00030] Robot arm 72 corresponds to the second robot arm of the disclosure, and includes a suction holder 70 held at the leading end thereof. Suction holder 70 includes a plurality of suction nozzles 71 arranged in the longitudinal direction of a rod-like air tube 73 extending in the x-direction shown in FIG. 1. The air tube 73 is a hollow tube having closed opposite ends, and the interior of the air tube 73 is communicated with a suction source (not shown) via a control valve. When the control valve is open and the suction nozzles 71 suck air, the suction nozzles 71, i.e., held on the suction holder 70, can hold the interleaf paper 5 by suction. From this state, when the control valve is closed to stop suction by the suction nozzles 71, the interleaf paper 5 is released from the suction of the suction holder 70. The suction holder 70 and the robot arm 72 configured to move the suction holder 70 form the interleaf paper transfer unit of the disclosure.

[00031] Among the guide rollers 43 to 48, the guide rollers 47 and 48 are arranged to nip the web 5W therebetween. The guide rollers 47 and 48 can be rotatably driven by a driving means (not shown) to feed the web 5 W nipped therebetween to the left as shown in FIG. 1. That is, the guide rollers 47 and 48 and the above-described roll shaft driving means 42 form the web spreading unit configured to spread the web 5W by unwinding the web 5 W from the leading end side thereof.

[00032] The web 5W fed by the guide rollers 47 and 48 is guided by the guide 50 such that the leading end of the web 5W moves down from above the glass sheet placing surface 6a of the crate 6 to allow the web 5W to face the glass sheet placing surface 6a. That is, the guide 50 forms the web guide of the disclosure.

[00033] The cutter 51 includes a lower blade 52 and a upper blade 53 disposed on the back side and the front side, respectively, relative to the web 5W. Each of the lower blade 52 and the upper blade 53 has a length that is longer than the width of the web 5W. The upper blade 53 is configured to reciprocate between a retracted position away from the lower blade 52 and a cutting position where the upper blade 53 engages with the lower blade 52. When the upper blade 53 is moved from the retracted position to the cutting position, the web 5W is cut across the width, for example the entire width, at a predetermined distance from the leading end of the web 5W to form a single sheet of interleaf paper 5.

[00034] The suction bar 64 is located immediately below the cutter 51 , i.e., upstream the cutter 51 in a direction in which the web 5W is fed. The suction bar 64 is a hollow tube having closed opposite ends, and includes a plurality of suction holes 64a in a surface 64S facing the web 5W, as clearly shown in FIG. 2. The interior of the suction bar 64 is communicated with a suction source (not shown) via a control valve. When the control valve is open and the suction holes 64a suck air, the surface 64S can hold the web 5W or the interleaf paper 5 by suction. From this state, when the control valve is closed to stop suction by the suction holes 64a, the web 5W or the interleaf paper 5 is released from the suction of the suction bar 64. [00035] The suction bar 64 is moved by a driving means (not shown) in directions of arrows ml, m2, m3, and m4, as shown in FIG. 3, to four positions shown in FIG. 3. The first position is a web receiving position, which is shown in solid line in FIG. 3. In this position, the suction bar 64 is in the vicinity of the lower blade 52 of the cutter 51 and the surface 64S is slightly spaced from an extended line of a back side 5B (the side which is brought into contact with the glass sheet placing surface 6a of the crate 6) of the web 5W held by the guide 50. The web receiving position is denoted by PI , and the suction bar 64 in this position is denoted by "64(P1)" in FIG. 3. The second position is a retracted position P2, to which the suction bar 64 is moved from the web receiving position PI in a direction away from the web 5W. The suction bar 64 in the retracted position P2 is denoted by "64(P2)" in FIG. 3. The third position is a lower end position P3, to which the suction bar 64 is slightly moved from the web receiving position PI in a direction in which the web 5W is fed. The suction bar 64 in the lower end position P3 is denoted by "64(P3)" in FIG. 3. The fourth position is a lower end retracted position P4, to which the suction bar 64 is moved from the lower end position P3 in a direction away from the web 5W. The suction bar 64 in the lower end retracted position P4 is denoted by "64(P4)" in FIG. 3.

[00036] The pair of guide bars 60 are disposed at positions laterally outside and spaced from the left and right ends, respectively, of the crate 6, as clearly shown in FIG. 2. Each guide bar 60 includes an elevator block 61 attached thereto, which moves up and down along the guide bar 60, and the clamper 62 is mounted to the elevator block 61. These two elevator blocks 61 are moved up and down synchronously to be kept at the same position of height relative to each other. Each clamper 62 holds the web 5W at the inner end of the clamper 62, i.e., at the end facing the other clamper 62. Further, each clamper 62 is movable in the horizontal direction, i.e., in the direction of arrow X (±X-direction) as shown in FIG. 2, on the elevator block 61. This movement occurs synchronously such that the two clampers 62 are moved toward or away from each other. The guide bars 60, the elevator blocks 61, and the clampers 62 described above form the web pull down unit of the disclosure.

[00037] More specifically, as shown with being enlarged in FIG. 4, each clamper 62 includes a base 62a mounted to the elevator block 61, and a pair of clamp halves 62b, 62b attached to the inner end of the base 62a. The base 62a is moved relative to the elevator block 61 in the direction of arrow X. The pair of clamp halves 62b, 62b are moved synchronously toward or away from each other in the direction of arrow H.

[00038] When the clampers 62 hold the web 5W, first, the pair of clamp halves 62b, 62b of each clamper 62 are positioned at a maximum distance from each other. Further, the bases 62a, 62a of the pair of clampers 62 are positioned at a maximum distance from each other such that they are disposed at positions laterally outside and spaced from the left and right ends, respectively, of the web 5W. From this state, the bases 62a, 62a are moved inward until the web 5W is positioned between the pair of clamp halves 62b, 62b of each clamper 62, and then the pair of clamp halves 62b, 62b are moved toward each other. In this manner, the web 5W is held by the pair of clamp halves 62b, 62b of each clamper 62. That is, when it is said that "the clampers 62 hold the web 5W", it more specifically means that the clamp halves 62b, 62b of each clamper 62 holds the web 5W. From this web-holding state, when the pair of clamp halves 62b, 62b are moved away from each other, the web 5W is released from the clamp halves 62b, 62b. That is, when it is said that "the clampers 62 release the web 5W", it more specifically means that the clamp halves 62b, 62b of each clamper 62 release the web 5W. It should be noted that, in the case where the web 5W has already been cut into a sheet of interleaf paper 5, as described later, the above-described holding and releasing of the web 5W by the clampers 62 means holding and releasing of the interleaf paper 5 by the clampers 62.

[00039] Now, operation of the glass sheet packing system 1 having the above -described features is described. When a plurality of glass sheets G are packed on a crate 6 by the glass sheet packing system 1 , first, the web 5 W is cut into a predetermined length to form a sheet of interleaf paper 5, and then the sheet of interleaf paper 5 is placed on the glass sheet placing surface 6a of the crate 6. Then, a glass sheet G is placed thereon, and another sheet of interleaf paper 5 is placed on the glass sheet G. This process is repeated to alternately accumulate the glass sheets G and the sheets of interleaf paper 5 on the glass sheet placing surface 6a of the crate 6.

[00040] FIG. 5 shows the speed of feeding (spreading) of the web 5 W by the web spreading unit comprised of the guide rollers 47, 48 and the roll shaft driving means 42, and the speed of movement of the clampers 62 along the guide bars 60 (i.e., movement of the elevator blocks 61) during the above-described process. In FIG. 5, the former speed is represented by the dot-and-dash line, and the latter speed is represented by the thick solid line. With respect to the latter speed, the speed of downward movement along the guide bars 60 is shown as "+" (plus) values, and the speed of upward movement is shown as "-" (minus) values. The following description is given with reference to FIG. 5. [00041] First, before the step of cutting the web 5W, i.e., at time TO shown in FIG. 5, the suction bar 64 is in the web receiving position PI shown in FIG. 3. At that time, the pair of elevator blocks 61 are in the uppermost position, where the clampers 62 are in positions above the suction bar 64 (i.e., in the vicinity of the guide 50). The pair of clampers 62 are at positions laterally (in the direction of arrow X) outward and away from the left and right ends, respectively, of the web 5W. During a period from this state, i.e., the time TO, to time Tl shown in FIG. 5, the pair of clampers 62 are moved toward each other and hold lateral ends in the vicinity of the leading end of the web 5W.

[00042] After the web 5W is held by the pair of clampers 62, pulling down of the web 5W by downward movement of the clampers 62, i.e., downward movement of the elevator blocks 61, and spreading of the web 5W by the guide rollers 47, 48 and the roll shaft driving means 42 begin. This begins at time Tl shown in FIG. 5. Before the downward movement of the elevator blocks 61, the suction bar 64 is moved to the retracted position P2 shown in FIG. 3 so as not to interfere with the elevator blocks 61 and the clampers 62 moving downward.

[00043] When a predetermined time is elapsed from the start of the downward movement of the elevator blocks 61, a drive source (not shown) of the elevator blocks 61 is turned off. The elevator blocks 61 continue the downward movement by inertia after the drive source is turned off, and thereafter completely stop at time T4 shown in FIG. 5. That is, the elevator blocks 61 and the clampers 62 move downward and pull down the web 5W for a period from the time Tl to the time T4 shown in FIG. 5. It should be noted that the period from the time Tl to the time T4 corresponds to the first period of time of the disclosure. Immediately before the pulling down of the web 5W completely stops, the suction bar 64 returns from the retracted position P2 to the web receiving position PI shown in FIG. 3. Before that, the suction bar 64 is in the retracted position P2, and thus the web 5W being pulled down does not touch the surface 64S of the suction bar 64.

[00044] When the suction bar 64 is returned to the web receiving position PI and the pulling down of the web 5W is completely stopped, the suction holes 64a of the suction bar 64 suck air. Thus, the web 5W is suctioned on the surface 64S, which is the suction surface, of the suction bar 64, and the web 5W is held in a fixed position, i.e., such that the web 5W is not easily movable. It should be noted that the period from the time T4 shown in FIG. 5, when the pulling down of the web 5W completely stops, to the time T5 shown in FIG. 5, when the pulling down of the web 5W is started again, corresponds to the rest period of time of the disclosure. It should be noted that the suction holder 70 may also serve to hold the web 5 W in the fixed position. [00045] When the web 5W is held in the fixed position as described above, the upper blade 53 of the cutter 51 is driven to cut the web 5W across the width, for example the entire width, thereof at the position of the upper blade 53. In this manner, the web 5W is cut to form the sheet of interleaf paper 5. The holding and the cutting of the web 5W in the fixed position are performed during the rest period of time. The length from the leading end of the web 5W to the position where the web 5W is cut is unchanged as long as the speed of the downward movement of the elevator blocks 61 and the length of the first period of time are not changed. In this manner, a predetermined length of the interleaf paper 5 slightly greater than the length of the glass sheet G can be set. On the other hand, a predetermined width of the interleaf paper 5 slightly greater than width of the glass sheet G can be set by selecting and using the web 5W having an appropriate width. FIG. 6 shows the state where a sheet of interleaf paper 5 is formed after the state shown in FIG. 3. In this state, the suction bar 64 holds a portion of the interleaf paper 5 in the vicinity of the trailing end thereof by suction. The trailing end of the interleaf paper 5 refers to an end in the vicinity of the guide 50, i.e., the upper end of the interleaf paper 5.

[00046] After the web 5 W is cut, the robot arm 72 of the interleaf paper transfer robot 63 is driven to set the suction holder 70 coupled to the robot arm 72 in a position shown by dashed line in FIG. 6. This position of the suction holder 70 is slightly below the suction bar 64 in the web receiving position PI , where the suction holder 70 faces and is slightly spaced from the interleaf paper 5. When the suction holder 70 is brought into this position, then, the suction bar 64 is moved downward to the lower end position P3 shown in FIGs. 3 and 6 while it holds the portion of the interleaf paper 5 in the vicinity of the trailing end thereof by suction. This downward movement of the suction bar 64 begins at time T5 shown in FIG. 5. Synchronously with the downward movement of the suction bar 64, the clampers 62 holding the interleaf paper 5 (i.e., the elevator blocks 61) begin to move downward.

[00047] When the suction bar 64 reaches the lower end position P3, the robot arm 72 is driven to bring the suction holder 70 into contact with the interleaf paper 5. Then, the suction nozzles 71 of the suction holder 70 suck air to hold a portion in the vicinity of the upper end of the interleaf paper 5 on the suction holder 70 by suction. As the interleaf paper 5 is held by the suction holder 70 by suction, the suction of the suction holes 64a of the suction bar 64 is stopped to release the interleaf paper 5 from the suction bar 64. That is, the interleaf paper 5 is transferred from the suction bar 64 to the suction holder 70 and is held by the suction holder 70 by suction. This transfer is performed immediately after the time T5 shown in FIG. 5. It should be noted that the length of the suction surface of the suction holder 70 having the suction nozzles 71 formed therein is the same as or slightly greater than the entire width of the web 5 W, such that the suction surface of the suction holder 70 can pass through between the left and right guide bars 60. It should be noted that the positions of the robot arm 72 and the suction holder 70 shown in solid line in FIG. 1 are positions when the suction holder 70 holds the interleaf paper 5 by suction in the manner described above.

[00048] The suction holder 70 holding the interleaf paper 5 by suction is moved downward by the robot arm 72 driven in synchronization with downward movement of the clampers 62 holding the interleaf paper 5 (i.e., downward movement of the elevator blocks 61). That is, the interleaf paper 5 is transferred by the suction holder 70 at the same time with the pulling down of the interleaf paper 5 by the downward movement of the clampers 62. It should be noted that, immediately before the pulling down and the transfer of the interleaf paper 5 begin, the suction bar 64 is moved from the lower end position P3 shown in FIGs. 3 and 6 to the lower end retracted position P4 to prevent the interleaf paper 5 from touching the surface 64S of the suction bar 64. When the suction bar 64 reaches the lower end retracted position P4, it is moved to the retracted position P2, and then to the web receiving position PI in preparation for the next cutting of the web 5W.

[00049] The robot arm 72 moves the suction holder 70 downward along the glass sheet placing surface 6a of the crate 6 to a position where the lower end of the interleaf paper 5 held by suction by the suction holder 70 is almost aligned with the upper surface of the bottom plate 6b, and then moves the suction holder 70 toward the glass sheet placing surface 6a. In this manner, the interleaf paper 5 is almost in contact with the glass sheet placing surface 6a when no glass sheet G is placed on the glass sheet placing surface 6a, or the interleaf paper 5 is almost in contact with a glass sheet G placed on the glass sheet placing surface 6a.

[00050] The pair of elevator blocks 61 moved downward together with the suction holder 70 are stopped before the suction holder 70 is moved toward the glass sheet placing surface 6a. Then, after a while, the pair of elevator blocks 61 are moved upward along the guide bars 60, and then are stopped. The timing of operation of the elevator blocks 61 at this time is described with reference to FIG. 5. The downward movement begins at the time T5, and the downward movement is completely stopped at time T6. Then, the upward movement begins at time T7, and the upward movement is completely stopped at time T10. The period from the time T5 to the time T6 corresponds to the second period of time of the disclosure. It should be noted that, when the downward movement of the pair of elevator blocks 61 is stopped as described above, the clampers 62 held by the respective elevator blocks 61 release the interleaf paper 5, and the clampers 62 are moved laterally outward to be completely separated from the interleaf paper 5. The interleaf paper 5 released from the clampers 62 is received by the bottom plate 6b of the crate 6 from below and placed on the glass sheet placing surface 6a or on the glass sheet G that has already been placed on the glass sheet placing surface 6a.

[00051] The position where the pair of elevator blocks 61 moved upward is completely stopped is the previously described uppermost position. In this uppermost position, the elevator blocks 61 wait for the next pulling down of the web 5W. The time when the elevator blocks 61 are returned to the uppermost position (the time T10) is near the time when the interleaf paper 5 is almost in contact with the glass sheet placing surface 6a or the glass sheet G. That is, the elevator blocks 61 are returned to the uppermost position before one glass sheet G is placed on this interleaf paper 5, as described later. At the time when the elevator blocks 61 are returned to the uppermost position, the clampers 62 having been moved laterally outward, as described above, are in positions laterally outside and spaced from the left and right ends of the web 5W.

[00052] It should be noted that the speed of downward movement of the suction holder 70 along the glass sheet placing surface 6a is set to be slightly higher than the speed of downward movement of the elevator blocks 61 that are moved downward together with the suction holder 70. This prevents the interleaf paper 5 held by the suction holder 70 and the clampers 62 from being broken by tension which is otherwise exerted by the suction holder 70 and the clampers 62.

[00053] Next, how the glass sheets G are placed is described. For example, near the time when the web 5W is cut as described above, the dolly 12 holding a single glass sheet G runs along the rail 11 for a predetermined distance in the direction of arrow X (+X-direction) shown in FIG. 2, and is stopped. When the dolly 12 is stopped, the glass sheet G held by the dolly 12 is in the previously described position where the center in the horizontal direction of the glass sheet G is aligned with the center in the horizontal direction of the glass sheet placing surface 6a of the crate 6. Setting the position where the glass sheet G is stopped relative to the crate 6 in this manner allows minimizing the path along which the glass sheet G is fed to the crate 6. This, in turn, allows reducing the time to accumulate the glass sheets. [00054] When the dolly 12 is stopped, the robot arm 24 of the glass sheet feeding robot 23 is driven to move the glass sheet holding frame 21 into a position where the suction nozzles 22 are in contact with one surface of the glass sheet G. Then, the suction nozzles 22 suck air to hold the glass sheet G on the glass sheet holding frame 21. As the glass sheet G is held by the glass sheet holding frame 21 by suction in this manner, the holder 13 of the dolly 12 releases the glass sheet G. Then, the dolly 12 is moved away from the glass sheet feeding apparatus 20 to run along the circular rail 1 1 back to the previously-mentioned glass sheet manufacturing section.

[00055] At the time when the glass sheet holding frame 21 holds the glass sheet G, the sheet of interleaf paper 5 is almost in contact with the glass sheet placing surface 6a of the crate 6 or the glass sheet G which has already been placed on the glass sheet placing surface 6a, as described above. Subsequently, the robot arm 24 of the glass sheet feeding robot 23 is driven to move the glass sheet holding frame 21 to a position where the glass sheet G is held over the interleaf paper 5 with the lower end of the glass sheet G being almost aligned with the upper surface of the bottom plate 6b of the crate 6. In this state, the suction by the suction nozzles

22 is stopped and the glass sheet G is released from the glass sheet holding frame 21 to be placed on the interleaf paper 5. Thereafter, the robot arm 24 of the glass sheet feeding robot

23 is driven to return the glass sheet holding frame 21 to a position for holding the next glass sheet G fed thereto.

[00056] In the state where the glass sheet G is placed on the interleaf paper 5 and the interleaf paper 5 is pressed by the weight of the glass sheet G, the suction by the suction holder 70 is stopped, and interleaf paper 5 is released from the suction of the suction holder 70. Subsequently, the robot arm 72 of the interleaf paper transfer robot 63 is driven to return the suction holder 70 upward to a position for holding the web 5W next time. It should be noted that the positions of the robot arm 72 and the suction holder 70 shown in dashed line in FIG. 1 are positions when the glass sheet G is placed on the interleaf paper 5, as described above.

[00057] The above-described process is repeated to alternately accumulate the glass sheets G and the sheets of interleaf paper 5 on the glass sheet placing surface 6a of the crate 6 in a standing position. As described previously, the length and width of the sheet of interleaf paper 5 are greater than the length and width, respectively, of the glass sheet G and this allows protecting the entire surface of the glass sheet G with the interleaf paper 5. It should be noted that, in this embodiment, the glass sheets G are accumulated with the so-called side A (a glass surface to be the front side of a product that is produced using the glass sheet G) of each glass sheet G facing upward, as one example. [00058] As shown in FIG. 5, the speed of spreading of the web 5 W by the guide rollers 47, 48 and the roll shaft driving means 42 and the speed of pulling down of the web 5W by the downward movement of the clampers 62 gradually increase from the start of the spreading and the pulling down, and after the speeds reach their maximum values, the maximum values are kept for a predetermined time. For example, the speed of spreading of the web 5W is kept at the maximum value for a period from the time T2 to the time T8. Then, when the spreading and the pulling down of the web 5W are stopped, the speed of spreading and the speed of pulling down gradually decrease from their maximum speeds to finally reach 0. The speed of pulling down of the web 5W reaches 0 at the time T4 and the time T6, and the speed of spreading of the web 5 W reaches 0 at the time T9.

[00059] The spreading of the web 5W is achieved by unwinding the web 5W on the roll shaft 41. Thus, in general, the maximum value of the speed of spreading the web cannot be increased as high as the maximum value of the speed of pulling down the web, as shown in FIG. 5. For this reason, the speed of movement of the web 5W downstream the dancer roller 49 shown in FIG. 1 is higher than the speed of movement of the web 5W upstream the dancer roller 49 (between the dancer roller 49 and the roll shaft 41). The difference of the speed of movement appears as a difference of the amount of movement of the web 5W. The difference of the amount of movement of the web 5W is absorbed by the dancer roller 49 moving upward relative to the position shown in FIG. 1. That is, the dancer roller 49 is configured to be movable up and down to cause the web 5W to slack, and to absorb the slack of the web 5W. The slack of the web 5W is absorbed when the dancer roller 49 moves downward. In the example shown in FIG. 5, the difference of the amount of movement of the web 5W gradually increases from the time Tl and reaches the maximum value at time T3. This difference of the amount of movement is absorbed when the dancer roller 49 moves upward to release the slack. Accordingly, the dancer roller 49 is formed to allow a sufficient upward and downward stroke to absorb the difference of the amount of movement of the web at the time T3.

[00060] Applying the dancer roller 49 that operates as described above allows high-speed pulling down the web 5W with the elevator blocks 61 and the clampers 62, and this is advantageous in reducing the time to complete the process from the cutting of the web 5W to the placement of the glass sheet G. It should be noted that, for example, during the period from the time T6 to the time T9 shown in FIG. 5, the web 5W is not pulled down, while the web 5W is spread from the roll shaft 41. Accordingly, the web 5W slacks during this period, and the dancer roller 49 moves downward to absorb the slack.

[00061] As described above, in the glass sheet packing system 1 of this embodiment, a sheet of interleaf paper 5 formed by cutting the web 5W is transferred from the clampers 62, which form the web pull down unit, to the suction holder 70, which forms the interleaf paper transfer unit together with the robot arm 72, in the course of moving the sheet of interleaf paper 5 to the lowermost position to place the interleaf paper 5 on the crate 6. To feed the interleaf paper 5 onto the glass sheet placing surface 6a of the crate 6, the robot arm 72, which is relatively incapable of high speed operation but is capable of high precision operation, is used to transfer the interleaf paper 5. On the other hand, to pull down the web 5W before the transfer, the elevator blocks 61 and the clampers 62, which are capable of high speed operation, are used. Increasing the speed of pulling down of the web 5W in this manner allows reducing the time to complete the process from the cutting of the web 5W to the placement of the glass sheet G.

[00062] Further, transferring the sheet of interleaf paper 5 from the clampers 62 to the suction holder 70, as described above, allows the elevator blocks 61, which form the web pull down unit, to return to the uppermost position to begin the next pulling down of the web before the sheet of interleaf paper 5 reaches the lowermost position, i.e., before one glass sheet G is placed on the sheet of interleaf paper 5. This feature of the glass sheet packing system 1 of this embodiment also contributes to reducing the time to complete the process from the cutting of the web 5W to the placement of the glass sheet G.