Folding machine of a rotary press.

BACKGROUND OF THE INVENTION:

Field of the Invention:

0001The present invention relates to a folding machine of a rotary press of the type that after superpos­ed paper sheets have been cut out by means of a folding drum and a cutting drum, a folding blade is projected from the same folding drum to insert the cut paper sheets between a pair of folding rollers for folding them.

Description of the Prior Art:

0002Explaining now a folding machine of a rotary press in the prior art with reference to Figs. 13 and 14, reference numeral 1 designates superposed paper webs formed by superposing a plurality of traveling paper webs, numeral 2 designates a pair of nipping rollers, numeral 3 designates a cutting drum, numeral 4 designates a folding drum, numeral 5 designates a folding blade provided in the same folding drum 4, numerals 7a and 7b designate a pair of folding rollers, numeral 9 designates a runner, and numeral 10 designates a paper sheet discharging con­veyor. The arrangement is such that superposed paper webs 1 consisting of a plurality of traveling paper webs superposed on one another are led through a gap between the pair of nipping rollers 2 to a gap space between the cutting drum 3 and the folding drum 4, where they are cut into cut paper sheets 6, subsequently the folding blade 5 provided in the folding drum 4 is projected to insert a central portion of the cut paper sheets 6 into a gap space between the pair of folding rollers 7a and 7b, thereby they are pinched by these folding rollers 7a and 7b to form twice-folded portions 6a and 6b and to discharge them downwards through the gap clearance between the folding rollers 7a and 7b, and further, the twice-folded paper sheets are made to fall on the paper sheet discharging conveyor 10 via the runner 9 to be sent to the subsequent step.

0003In the folding machine of a rotary press shown in Figs. 13 and 14, for the purpose of regularly perform­ing folding of the cut paper sheets 6, it is necessary to adjust gap clearances Sa and Sb between the pair of fold­ing rollers 7a, 7b and the folding blade 5 depending upon a number of completed pages, and to that end a gap adjust­ing device as shown in Fig. 9 is provided. Reference numeral 08 in Fig. 9 designates a screw shaft having both left-hand and right-hand threads 08a and 08b, and to this screw shaft 08 is transmitted rotation of a motor or a handle 013 in a driving device via a coupling 014, and it is thereby rotated. When the screw shaft 08 rotates, joint members 015 restrained from rotation would slide in the directions of arrows A and B jointly with adjusting nuts 018 which have female screws and threadedly engaged with the screw shaft 08, hence arms 022a and 022b are rotated about fulcrum points at the center of support shafts 023a and 023b via links 021 and pins 024a and 024b, and thereby a gap space S between the folding rollers 7a and 7b is adjusted. It is to be noted that a spring 26 biases the joint members 015 so that they may be always butted against shoulder portions of the adjusting nuts 018.

0004As described above, while the gap adjusting device for the folding rollers shown in Fig. 9 is a device making use of a single spring 026, as one example of the prior art devices making use of two springs, a folding mechanism for use in a rotary press disclosed in Laid-­Open Japanese Patent Specification No. 51-115120 (1976) and shown in Figs. 10, 11 and 12 of this application is known. In this folding mechanism for use in a rotary press, blocks 035 and 036 are swingably supported via cushion rubbers 043 and 044 from tip end portions of sup­port arms 031 and 032, respectively, which in turn support folding rollers 7a and 7b, respectively, and can rotate about support shafts 033 and 034, respectively. In addi­tion, stop members 037 and 038 fit around eccentric cams 045 and 046 mounted to a shaft 047. At an axial end por­tion of the shaft 047 is fixed a worm wheel 048, which is adapted to be rotated by a worm 049, hence as a result of rotation of the worm 049 the eccentric cams 045 and 046 rotate, thus the support arms 031 and 032 are rotated via the stop members 037 and 038 and the blocks 035 and 036, and the gap space S between the folding rollers 7a and 7b can be adjusted. At this time, the stop members 037 and 038, the blocks 035 and 036 and springs 041 and 042, respectively, would move integrally.

0005However, in the gap adjusting device for the folding rollers in the prior art shown in Fig. 9, in the event that a deviated load has been applied to the device, the respective folding rollers would mutually affect via the springs, and so, the respective folding rollers would rotate and vibrate. Therefore, normally an arm on one side (the arm 022b in Fig. 9) is fixed. But if the gap space between the respective folding rollers is made smaller than the thickness of the paper sheets for the completed pages in order to insure the folding, since the gap space between the fixed side folding roller and the folding blade is small, breaking damages or the like are produced in the paper sheets and thus just the opposite effect would be brought about, and therefore, it is prac­tically impossible to reduce the gap space between the respective folding rollers up to a gap distance smaller than the paper sheet thickness of the completed pages, and setting of the gap space between the respective folding rollers at a high precision is required.

0006On the other hand, in the heretofore known folding mechanism for use in a rotary press shown in Figs. 10, 11 and 12, in the case where it is necessary to make the arms large, the mass of the arms also become large, hence shock upon operation is large, and so, any countermeasure for enhancing a mechanical strength, preventing abrasion and lowering a noise level becomes necessary. In view of this necessity, in the folding mechanism for use in a rotary press shown in Figs. 10, 11 and 12, special cushion rubbers 043 and 044 are mounted to the shafts 051 and 052 for connecting the support arms 031 and 032 with the stop members 037 and 038. However, since they are elastic bodies, it would prastically deform, and the preset gap space would change. In addition, as the adjustment of gap space is performed by means of eccentric cams and a worm wheel and a worm for driving the eccentric cams, the cam shaft would rotationally vibrate as a result of an impact force, and hence, the worm wheel and the worm are liable to generate surface peel at their contact surfaces. Moreover, in the event that the machine is operated with the gap space preset to be small with respect to the number of completed pages in order to form a fold in a thickly superposed sheets, there were the problems that response characteristics of the folding rollers which continuously and periodically pinch paper sheets would be deteriorated, the pressing would become unreliable and the pressing force would become insufficient because the mass and inertia of the arms are large as described above.

0007In addition, in the case where a number of com­pleted pages is large (thick pages), a fold is hardly formed at the boundary between the twice-folded portion 6a and the twice-folded portion 6b by merely adjusting the above-mentioned gap space between the pair of folding rollers 7a and 7b with the aid of the gap adjusting device for folding rollers in the prior art as shown in Fig. 9, and therefore, the folding machine was once stopped and the folding blade 5 was adjusted in such manner that a distance Ak (See Fig. 6) between the tip end of the fold­ing blade 5 and the straight line connecting the centers of the pair of folding rollers 7a and 7b may become larger than a corresponding distance An (See Fig. 7) in the case of a small number of completed pages (thin pages).

0008However, in a recent rotary press, a number of completed pages of paper sheets is increasing and a page number difference between thick pages and thin pages is expanding. Accordingly, even if the gap space between the folding rollers 7a and 7b is adjusted with the posi­tion of the tip end of the folding blade 5 held at the position corresponding to thin pages, the state shown in Fig. 8 occurs, hence when superposed paper sheets 6 having thick pages are folded, a fold is not given to the paper sheet on the outside, and the tip end portion at the loca­tion to be folded would come out of the folding machine in a swelled condition. Consequently, when the folded paper sheets are stacked up in a subsequent processing apparatus, for instance, on a paper sheet discharging conveyor 10, they would fall down. Or else, if one intend to forcibly form a fold and even if the pressing force of the folding rollers 7a and 7b are increased by strengthen­ing the resilient forces of the springs (for instance, the spring 026 in Fig. 9 or the springs 041 and 042 in Figs. 10 - 12), merely the forces for pressing the side surface of the folded paper sheets are increased and a fold is not formed, and on the contrary the paper sheets are damaged by the folding rollers 7a and 7b, resulting in faults in quality. On the contrary in the case where superposed paper sheets 6 having thin pages are folded with the tip end portion of the folding blade 5 kept adjusted at the position corresponding to thick pages as shown in Fig. 7, even if the gap space between the folding rollers 7a and 7b is adjusted, the superposed paper sheets 6 cannot be forcibly insert into the gap space between the folding rollers 7a and 7b, and this causes stopping of paper sheets. From the above reasons, it is necessary to adjust the position of the tip end of the folding blade 5 with respect to the folding rollers 7a and 7b according to the completed pages, but this adjustment requires skill. In addition, as the above-mentioned adjustment is carried out after stopping the folding machine, there was a prob­lem that the rate of operation of the rotary press was lowered.

SUMMARY OF THE INVENTION:

0009The present invention has been worked out in view of the aforementioned problems in the prior art, and one object of the present invention is to provide an improved folding machine of a rotary press, in which fold­ing can be effected reliably, good folds can be formed, and in addition to that quality of folded paper sheets can be improved, troubles in an operation such as stopping of paper sheets or the like can be prevented.

0010Another object of the present invention is to provide a novel moving device for folding rollers in a folding machine of a rotary press, in which in addition to that faults in quality can be eliminated, falling down of folded paper sheets on the subsequent processing device can be prevented, and the rate of operation of the rotary press can be improved.

0011In order to achieve the aforementioned objects, according to one feature of the present invention, in a folding machine of a rotary press of the type that after superposed paper sheets have been cut out by means of a folding drum and a cutting drum, a folding blade is pro­jected from the folding drum to insert the cut paper sheets between a pair of folding rollers for folding them, a gap adjusting device for adjusting a gap space between the respective folding rollers is composed of a pair of support arms for the folding rollers which are swingable about a pair of fixed shafts disposed in parallel to the axes of the respective folding rollers, vertically movable adjusting tables disposed under the respective support arms for the folding rollers, and a pair of links for connecting the adjusting tables with the respective sup­port arms for the folding rollers.

0012According to another feature of the present invention, in a gap adjusting device for folding rollers in a folding machine of a rotary press of the type that a pair of folding rollers are disposed in opposition to a projecting portion of a folding blade provided in a folding drum with a gap space therebetween made adjustable, a pair of arms respectively pivotably supporting the fold­ing rollers are coupled via a pair of adjusting levers pivotably supported from a single support shaft disposed under a middle portion of the support shafts of the arms, and links.

0013According to still another feature of the present invention, in a folding machine of a rotary press of the type that superposed paper sheets cut out by means of a folding drum and a cutting drum of the folding machine are twice-folded by projecting a folding blade provided in the folding drum of the folding machine of the rotary press into the gap space between a pair of folding rollers, the aforementioned respective folding rollers and a gap adjust­ing device of folding rollers for adjusting the gap space between the respective folding rollers depending upon a number of sheets of the aforementioned superposed paper sheets are held by a same support table, and the support table is supported so as to be movable with respect to the aforementioned folding drum in the radial direction thereof.

0014According to the present invention, since the folding machine of a rotary press is constructed in the above-described manner, in a first aspect of the invention, the adjusting tables are raised or lowered and their movement is transmitted via the respective links to the respective support arms of the folding rollers, and the gap space between the respective folding rollers is ad­justed by making the respective support arms of the fold­ing rollers swing about respective fixed shafts.

0015Also, in a second aspect of the present inven­tion, by adjusting the adjusting levers, the arms are adjusted via the links, and thereby the gap space between the folding rollers pivotably supported by the arms can be adjusted.

0016Still further, in a third aspect of the present invention, when paper sheets of thick pages are to be folded, a driving system for a support table is actuated in one direction to lower the support table and the re­spective folding rollers with respect to the folding drum, and thereby upon folding, component forces of the pressing forces of the respective folding rollers are acted upon the boundary of the twice-folded portion of the superposed paper sheets. At that time, a folding gap space is ad­justed by means of a gap space adjusting device for fold­ing rollers disposed on the support table, thus the respective folding rollers would be precisely set at a predetermined position to surely form a fold. On the other hand when paper sheets of thin pages are to be folded, the driving system for the support table is actu­ated in the other direction, thereby the support table and the respective folding rollers are raised with respect to the folding drum, and the folded paper sheets are folded while being surely held by pressing forces of the respective folding rollers acting upon the side surfaces of the paper sheets.

0017The above-mentioned and other objects, features and advantages of the present invention will become more apparent by reference to the following description of preferred embodiments of the invention taken in conjunc­tion with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

0018In the accompanying drawings: <ul id="ul0001" list-style="none"><li>Fig. 1 is a side view partly in vertical cross-­section of a first preferred embodiment of the present invention;</li><li>Fig. 2 is a side view of a second preferred embodiment of the present invention;</li><li>Fig. 3 is a side view of a third preferred embodiment of the present invention;</li><li>Fig. 4 is a vertical cross-section side view of the same;</li><li>Fig. 5 is a vertical cross-section front view of the same;</li><li>Fig. 6 is a schematic view for explaining an operation upon folding superposed paper sheets of thick pages;</li><li>Fig. 7 is a schematic view for explaining an operation upon folding superposed paper sheets of thin pages;</li><li>Fig. 8 is a schematic view for illustrating pressing forces of folding rollers;</li><li>Fig. 9 is a side view partly in vertical cross-­section showing a gap adjusting device for folding rollers in the prior art;</li><li>Fig. 10 is a side view showing a folding mecha­nism in a rotary press in the prior art;</li><li>Fig. 11 is a vertical cross-section front view taken along line XI-XI in Fig. 10 as viewed in the direc­tion of arrows;</li><li>Fig. 12 is an enlarged vertical cross-section side of the portion encircled by line XII;</li><li>Fig. 13 is a schematic side view showing a fold­ing machine of a rotary press in the prior art; and</li><li>Fig. 14 is a schematic view showing a gap space formed between respective folding rollers and a folding blade.</li></ul>

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

0019A first preferred embodiment of the present invention is illustrated in Fig. 1. In this figure, reference numeral 4 designates a folding drum, numerals 7a and 7b designate a pair of folding rollers, numerals 61a and 61b designate a pair of support arms for the folding rollers, numerals 62a and 62b designate a pair of fixed shafts which are in parallel to the axes of the respective folding rollers 7a and 7b, and the folding roller support arms 61a and 61b are swingably supported by the fixed shafts 62a and 62b. In addition, reference numerals 72a and 72b designates a pair of links, the lower end portions of these links 72a and 72b are rotatably supported by shafts 71a and 71b of vertically movable adjusting tables 80a and 80b, and stoppers 76a and 76b are fixedly secured to the upper end portions of the same links 72a and 72b. Also, joints 75a and 75b slidably fit around shaft portions of the links 72a and 72b, respectively, and the above-­mentioned folding roller support arms 61a and 61b are swingably mounted to the joints 75a and 75b, respectively. Springs 74a and 74b are interposed between the links 72a and 72b and the joints 75a and 75b are urged against the stoppers 76a and 76b, respectively. Consequently, the folding rollers 7a and 7b are pressed against the paper sheets at the positions corresponding to the adjusted gap space by the resilient forces of the springs 74a and 74b. If any external forces should act upon the folding rollers 7a and 7b, then the springs 74a and 74b would deform and the joints 75a and 76a would collide gainst the stoppers 76a and 76b, but as the lengths of the folding roller support arms 61a and 61b are short and their mass is also small, an impulsive force exerted at that time is small, and hence special cushion members are unnecessary. In addition, reference numeral 87 designates a base table, numerals 84 and 85 designate bevel gears rotatably mounted to the same base table 87, and these bevel gears are meshed with each other. Reference numeral 86 designates a universal joint for connecting a rotary shaft on the side of a handle (not shown) with a rotary shaft of the above-mentioned bevel gear 85, reference numeral 82p designates a screw shaft formed integrally with the above-­described bevel gear 84, and this screw shaft 82p is threadedly engaged with the above-mentioned adjusting tables 80a and 80b. Reference numerals 83a and 83b des­ignate guide members for guiding vertical movement of the aforementioned adjusting tables 80a and 80b.

0020Now, an operation of the folding machine of the rotary press shown in Fig. 1 will be explained in detail. The handle (not shown) is rotated, its rotation is trans­mitted to the screw shaft 82p by the intermediary of the route consisting of the universal joint 86 → the bevel gear 85 → the bevel gear 84 to rotate the screw shaft 82p, thereby the adjusting tables 80a and 80b threadedly engaged with the screw shaft 82p are raised or lowered, their movement is transmitted to the folding roller sup­port arms 61a and 61b via the links 72a and 72b, thus the folding roller support arms 61a and 61b are made to swing about the fixed shafts 62a and 62b, respectively, and the gap space S between the folding rollers 7a and 7b is adjusted.

0021Next, a second preferred embodiment of the present invention will be described with reference to Fig. 2. According to this preferred embodiment, like the folding machine in the prior art shown in Fig. 13, paper webs 1 consisting of a plurality of superposed running paper webs pass through a gap between a pair of nipping rollers 2, and are cut at the gap space between a cutting drum 3 and a folding drum 4, the cut paper sheets 6 have their central portion pushed down by a folding blade 5 disposed in the folding drum 4, the twice-folded portions 6a and 6b of the cut paper sheets 6 which have been pushed down, are pinched by a pair of folding rollers 7a and 7b, hence the cut paper sheets 6 are sent downwards in a folded state, and are ejected onto a discharging conveyor 10 by means of a runner 9.

0022In order to achieve the folding regularly, it is necessary to adjust the gap space between the pair of folding rollers 7a and 7b and the folding blade 5 depend­ing upon a number of completed pages. As shown in Fig. 2, a gap adjusting device for the folding rollers 7a and 7b in this preferred embodiment is composed of a pair of arms 110a and 110b pivotably supporting the folding rollers 7a and 7b, a pair of adjusting levers 113a and 113b pivotably supported from a single support shaft 112 disposed under a middle portion of support shafts 111a and 11lb of the arms 110a and 110b, and links 116a and 116b having one ends pivotably supported from the adjusting levers 113a and 113b via shafts 114a and 114b, respectively, with stoppers 115a and 115b at the other ends thereof butted against the arms 110a and 110b. These links 116a and 116b have their axial rods inserted in joints 117a and 117b which are pivotably supported from the arms 110a and 110b, respectively, and the links 116a and 116b have their stoppers 115a and 115b resiliently butted against the outer side surfaces of the joints 117a and 117b by means of springs 118a and 118b provided between their swingable end portions and the joints 117a and 117b.

0023At the tip ends of the adjusting levers 113a and 113b are swingably mounted blocks 119a and 119b, with the respective blocks 119a and 119b are threadedly engaged adjusting screws 120a and 120b which are threaded with a right-hand screw and a left-hand screw, respectively, these adjusting screws 120a and 120b are screw-coupled to a screw shaft 121, and the screw shaft 121 is in turn connected to a rotary shaft 123 via a universal joint 122.

0024Thus, as a result of rotation of the rotary shaft 123, the adjusting levers 113a and 113b would swing respectively in the opposite directions, due to the rotation of the adjusting levers the arms 110a and 110b would be rotated via the links 116a and 116b, respectively, to adjust the gap space between the folding rolls 7a and 7b, and the adjusted folding rolls 7a and 7b are pressed against the paper sheets by the resilient forces of the springs 118a and 118b. If the folding rolls 7a and 7b should vibrate due to any external forces, the springs 118a and 118b would somewhat deform and vibrate and impacts may arise between the joints 117a and 117b and the stoppers 115a and 115b, but since the arms 110a and 110b are short in length and small in mass, the amount of impacts is so little that a special cushion member is not necessitated.

0025Now a third preferred embodiment of the present invention will be described with reference to Figs. 3 to 5. In these figures, reference numeral 218 designates a fixed table, numeral 214 designates a screw shaft, and the upper and lower portions of this screw rod 214 are rotatably supported from the above-mentioned fixed table 218 via bearings 215 and 216 and a thrust bearing 217. Reference numeral 219 designates a bevel gear fixed to the upper end portion of the screw shaft 214, numeral 220 desig­nates another bevel gear meshed with the aforementioned bevel gear 219, numeral 220′ designates an adjusting shaft of a folding roller moving device which shaft is formed integrally with the bevel gear 220, and this adjusting screw 220′ extends from a handle or a motor (that is separate one from the handle or the motor of the gap ad­justing device for the folding rollers) and is rotatably mounted to the fixed table 218. Reference numeral 213 designates a boss threadedly engaged with the screw shaft 214, numeral 211 designates a support table fixed to the boss 213 by means of bolts, numerals 7a and 7b designate a pair of folding rollers, numeral 208 designates a gap adjusting device for the folding rollers, and this gap adjusting device 208 has a similar construction to the folding roller gap adjusting device shown in Fig. 9 and described previously. More particularly, reference numeral 228 designates a screw shaft (a screw shaft having left-­hand threads and right-hand threads), numerals 235a and 235b designate rods threadedly engaged with a left-hand screw portion and a right-hand screw portion of the screw shafts 228 and restrained from rotation by means of guide members, and numerals 240a and 240b designate arms having their lower end portions pivotably supported by the respec­tive rods 235a and 235b via pins 242a and 242b, respec­tively. Reference numerals 222a and 222b designate roller support arms, numerals 212a and 212b designate shafts for pivotably supporting the roller support arms 222a and 222b on the above-mentioned support table 211, and the upper portions of the aforementioned arms 240a and 240b are pivotably supported by the roller support arms 222a and 222b via pins 243a and 243b, respectively.

0026In this preferred embodiment, rotation of a handle or a motor (for instance, the handle 33 in Fig. 9 or the like) is transmitted to the screw shaft 208 (a screw shaft having left-hand threads and right-hand threads) to rotate the screw shaft 208, thereby the rods 235a and 235b threadedly engaged with the left-hand screw portion and the right-hand screw portion of the screw shaft 208 and restrained from rotation by means of guide members, are moved in the directions for approaching to each other or separating from each other, the movements of these rods 235a and 235b are transmitted via the respective arms 240a and 240b to the roller support arms 222a and 222b, hence the roller support arms 222a and 222b are made to swing about the shafts 212a and 212b, respectively, and thereby the gap space between the pair of folding rollers 7a and 7b and be adjusted depending upon a number of completed pages.

0027Now an operation of the folding roller moving device in the folding machine of the rotary press shown in Figs. 3, 4 and 5 will be described in detail. When superposed paper sheets 6 of thick pages are to be folded as shown in Fig. 6, the adjusting shaft 220′ of the fold­ing roller moving device is rotated in one direction by a handle or a motor, the rotation is transmitted via the bevel gear 220 and the bevel gear 219 to the screw shaft 214 to rotate the screw shaft 214 in one direction, and thereby the boss 213, the support table 211 and the fold­ing rollers 7a and 7b are lowered. Then, as shown in Fig. 6, component forces F′ of the pressing forces of the folding rollers 7a and 7b act upon the boundary of the twice-folded portions 6a and 6b of the superposed paper sheets 6, and a fold is surely formed. Since a folding gap space Sk can be adjusted by means of the folding roller gap adjusting device 208 disposed on the support table 211 for the folding rollers 7a and 7b, the folding rollers 7a and 7b would be set precisely at predetermined positions, and thus folding can be achieved reliably. On the other hand, when superposed paper sheets 6 of thin pages are to be folded, as shown in Fig. 7, the adjusting shaft 220′ of the folding roller moving device is rotated in the other direction by a handle or a motor, the rotation is transmitted via the bevel gear 220 and the bevel gear 219 to the screw shaft 214, to rotate the screw shaft in the other direction, and thereby the boss 213, the support table 211 and the folding rollers 7a and 7b are raised. At this time, the superposed paper sheets 6 can be folded while being surely holded by the pressing forces of the folding rollers 7a and 7b acting upon the side surfaces of the paper sheets.

0028In the folding machine of a rotary press accord­ing to the present invention, since the adjusting table is raised or lowered, its movement is transmitted via the respective links to the respective folding roller support arms, the respective folding roller support arms are made to swing about the respective fixed shafts and thereby the gap space between the respective folding rollers is adjusted as described above, response characteristics of the gap space adjustment are excellent, it is possible to operate the machine by presetting a gap space smaller than the number of completed pages depending upon a paper sheet thickness, folding can be achieved reliably, a good fold can be fold, thus quality of the folded paper sheets can be improved, and moreover, troubles in operations such as stoppage of paper sheets can be prevented.

0029In addition, in the folding machine of a rotary press according to the present invention, since a pair of arms for pivotably supporting folding rollers are connect­ed via a pair of adjusting levers pivotably supported from a single support shaft disposed under a middle portion of the support shafts of the arms, and a pair of links, the arms for pivotably supporting the rollers can be formed short and connected to the adjusting levers, and there­fore, a gap adjusting device which is small-sized and excellent in response characteristics can be provided. Accordingly, it is possible to operate the machine by presetting a gap space smaller than a number of completed pages depending upon a paper sheet thickness, thus folding can be achieved reliably, a good fold is formed, quality of folded paper sheets is improved, and also, troubles in operations such as stoppage of paper sheets can be pre­vented.

0030Furthermore, in the folding machine of a rotary press according to the present invention, as described above, when superposed paper sheets of thick pages are to be folded, a supporting table drive system is actuated in one direction to lower the supporting table and the respec­tive folding rollers with respect to the folding drum, and thereby upon folding, component forces of the pressing forces of the respective folding rollers are made to act upon a boundary between the twice-folded portions of the superposed paper sheets. At that time, the folding gap space is adjusted by the folding roller gap adjusting device disposed on the support table, the respective fold­ing rollers are preset precisely at predetermined posi­tions, and thereby a fold can be formed reliably. On the other hand, when superposed paper sheets of thin pages are to be folded, the supporting table drive system is actuated in the other direction to raise the supporting table and the respective folding rollers with respect to the folding drum, and the superposed paper sheets are folded while being reliably held by the pressing forces of the respective folding rollers acting upon the side surfaces of the paper sheets. Therefore, it would not occur that the superposed paper sheets are damaged by the respect folding rollers or a fold cannot be formed, thus faults in quality can be eliminated, and the folded paper sheets are prevented from falling down on the subsequent processing device. In addition, gap adjustment of the respective folding rollers and movement of the supporting table can be carried out during operation of a rotary press, and so, there is an advantage that the rate of operation of a rotary press can be improved.

0031While a principle of the present invention has been described above in connection to preferred embodiments of the invention, it is intended that all matter contained in the above description and illustrated in the accompany­ing drawings shall be interpreted to be illustrative and not as a limitation to the scope of the invention.