Patent Publication Number: US-2021178623-A1

Title: Sheet bundle cutting apparatus and bookbinding apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a sheet bundle cutting apparatus configured to cut an edge of a sheet bundle subjected to bookbinding, and to a bookbinding apparatus including the same. 
     BACKGROUND ART 
     Hitherto, there are sheet bundle cutting apparatus configured to cut and trim an edge of a sheet bundle subjected to bookbinding (PTL 1 and PTL 2). In each of those sheet bundle cutting apparatus, a cutting scrap generated when the edge of the sheet bundle subjected to bookbinding is cut is contained in a cutting scrap container. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Patent Application Laid-Open No. 2005-305822 
     PTL 2: Japanese Patent Application Laid-Open No. 2015-217494 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in the related-art sheet bundle cutting apparatus, when a cutting scrap is caused to fall and contained in the cutting scrap container, the cutting scrap sometimes falls into the cutting scrap container with its unbound portion spreading (see  FIG. 10B ). This is because a cover sheet is opened outward with a lapse of time after the binding is performed. When the cutting scrap is opened in this manner, the cutting scrap may be caught in the cutting scrap container or may become bulky inside the cutting scrap container, to thereby lead to a problem in that a cutting scrap containing efficiency of the cutting scrap container may deteriorate. 
     The present invention provides a sheet bundle cutting apparatus configured to suppress spreading of a cutting scrap of a sheet bundle and a bookbinding apparatus including this sheet bundle cutting apparatus. 
     Solution to Problem 
     According to the present invention, there is provided a sheet bundle cutting apparatus configured to cut a sheet bundle including a bound spine, the sheet bundle cutting apparatus comprising: pressure means for pressing the sheet bundle in a thickness direction of the sheet bundle while sandwiching a first surface and a second surface of the sheet bundle; cutting means for cutting, from the sheet bundle, a cutting scrap including a part of the spine; control means for controlling the pressure means and the cutting means, the control means being configured to cause the pressure means to press connection areas connected to the spine, which are respectively provided on the first surface and the second surface, and then cause the cutting means to cut the sheet bundle so that the cutting scrap includes a pressed area pressed by the pressure means; and containing means for containing the cutting scrap. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to suppress the spreading of the cutting scrap of the sheet bundle, thereby being capable of improving the cutting scrap containing efficiency of the cutting scrap container. 
     According to the present invention, the sheet bundle cutting apparatus having a high cutting scrap containing efficiency is provided, and hence the availability ratio of the bookbinding apparatus can be increased. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic sectional view for illustrating an image forming system including a bookbinding apparatus according to an embodiment of the present invention taken along a sheet conveyance direction. 
         FIG. 2  is a schematic sectional view for illustrating the bookbinding apparatus according to the embodiment of the present invention taken along a sheet conveyance direction. 
         FIG. 3  is a view for illustrating a cover sheet binding portion, a sheet bundle conveyance portion, a bundle attitude changing portion, a cutting portion, and a cutting scrap containing portion which are included in the bookbinding apparatus. 
         FIG. 4  is a control block diagram for illustrating an image forming apparatus and the bookbinding apparatus. 
         FIG. 5  is a flowchart of a bookbinding operation of the bookbinding apparatus. 
         FIG. 6  is a derived flowchart of the bookbinding operation of the bookbinding apparatus. 
         FIG. 7  is a flowchart of a cutting operation of the bookbinding apparatus according to a first embodiment. 
         FIG. 8  is a flowchart of a cutting operation of a bookbinding apparatus according to a second embodiment. 
         FIG. 9A  is a view for illustrating a cutting line and a pressed area of a sheet bundle covered with a cover sheet in the first embodiment. 
         FIG. 9B  is a view for illustrating a cutting line and a pressed area of a sheet bundle covered with a cover sheet in the second embodiment. 
         FIG. 10A  is a perspective view of a cut sheet bundle covered with the cover sheet and its cutting scrap. 
         FIG. 10B  is a perspective view of the cutting scrap in a spreading state. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
     Now, with reference to the drawings, description is made of an image forming system which includes a bookbinding apparatus according to a first embodiment of the present invention. 
       FIG. 1  is a schematic sectional view for illustrating an image forming system J including a bookbinding apparatus B according to the first embodiment of the present invention taken along a sheet conveyance direction.  FIG. 2  is a schematic sectional view for illustrating the bookbinding apparatus B according to the first embodiment of the present invention taken along a sheet conveyance direction. 
     The image forming system J includes an image forming apparatus A, the bookbinding apparatus B, and a post-processing apparatus C. The image forming apparatus A is configured to sequentially form toner images on sheets. The bookbinding apparatus B is arranged on a downstream side of the image forming apparatus A. The post-processing apparatus C is arranged on downstream of this bookbinding apparatus B. The image forming system J uses the bookbinding apparatus B to perform bookbinding processing on the sheets having been subjected to image formation in the image forming apparatus A. Further, the image forming system J allows sheets which are not subjected to the bookbinding processing to pass through the bookbinding apparatus B, uses the post-processing apparatus C to perform post-processing on the sheets, and discharges the sheets. 
     [Image Forming Apparatus A] 
     The image forming apparatus A is configured to form images on sheets. Examples of the image forming apparatus A may include those of various structures such as a copying machine, a printer, and a printing machine. The image forming apparatus A in this embodiment is a copying machine configured to form toner images on sheets. The image forming apparatus A includes, in an apparatus main body  1  thereof, a sheet supply portion  2 , a printing portion  3 , a sheet discharging port  14 , and an image forming apparatus control CPU  83 . In the sheet supply portion  2 , a plurality of cassettes  5  corresponding to respective sheet sizes are arrayed in an up-and-down direction. The sheet supply portion  2  sends out a sheet having a size designated by the image forming apparatus control CPU  83  to a feed passage  6 . In the feed passage  6 , a registration roller pair  7  is provided. The registration roller pair  7  aligns a leading end of the sheets, and feeds the sheet to the printing portion  3  on the downstream side at a predetermined timing. 
     The printing portion  3  includes an electrostatic drum (photosensitive drum)  10 . In a periphery of the electrostatic drum  10 , there are provided a print head  9 , a developing device  11 , and a transfer charger  12 . The print head  9  is formed of, for example, a laser emitter, and is configured to form an electrostatic latent image on the electrostatic drum  10 . The electrostatic latent image is developed with toner by the developing device  11  to be formed into a toner image, and the toner image is transferred onto a sheet by the transfer charger  12 . The sheet has the toner image fixed thereto by a fixing device  13  to be delivered to a sheet discharging passage  17 . A sheet discharging roller pair  15  is arranged at the sheet discharging port  14 . In a circulation passage  16 , the sheet conveyed from the sheet discharging passage  17  is reversed front and back in a switchback passage, and thereafter is guided to the registration roller pair  7  again. The printing portion  3  forms a toner image on a back surface of the sheet that has been conveyed along the circulation passage  16 . In such a manner, the sheet having the toner image formed on one side or both sides is conveyed from the sheet discharging port  14  to the bookbinding apparatus B. 
     A scanner unit  20  provided on top of the apparatus main body  1  is configured to optically read an image of an original. As generally known, the scanner unit  20  includes a platen glass  23 , a carriage  21 , and an optical reading means (for example, CCD device)  22 . The platen glass  23  is configured to receive an original to be placed thereon by a user. The carriage  21  is configured to optically read an original along the platen glass  23 . The optical reading means  22  is configured to perform photoelectric conversion on an optical image transmitted from the carriage  21 . Further, the scanner unit  20  includes, on top thereof, an original feeder  25  configured to automatically feed an original to the platen glass  23 . 
     [Bookbinding Apparatus B] 
       FIG. 2  is a schematic sectional view for illustrating the bookbinding apparatus B taken along the sheet conveyance direction. The bookbinding apparatus B is arranged to be connected to the image forming apparatus A. 
     In the following description, a sheet which serves as a cover sheet of a sheet bundle is referred to as “cover sheet”. A sheet covered with the cover sheet (sheet for the body) is referred to as “inner sheet”. A bundle of inner sheets is referred to as “inner sheet bundle”. The inner sheet bundle covered with the cover sheet is referred to as “sheet bundle covered with the cover sheet”. A sheet bundle covered with the cover sheet which has been trimmed is referred to as “booklet”. Those sheet bundles are simply referred to as “sheet bundle” in some parts. 
     As illustrated in  FIG. 10A , a sheet bundle C 3  covered with a cover sheet is formed by binding an inner sheet bundle C 1  at an end surface (spine) of its edge bound through application of an adhesive BN and covering the inner sheet bundle C 1  with a cover sheet C 2 . The cover sheet C 2  is pasted to the inner sheet bundle C 1  with the adhesive BN. The bookbinding apparatus B according to this embodiment has a function of suppressing a cutting scrap C 3 W, which is cut from the sheet bundle C 3  covered with the cover sheet and includes a portion (part of the spine) to which the adhesive BN is applied, from spreading as illustrated in  FIG. 10B . 
     As illustrated in  FIG. 1 , the bookbinding apparatus B includes the following components. That is, the bookbinding apparatus B includes: a casing  30 ; a stacking portion  40  configured to stack sheets having toner images formed thereon into a bundle and then align the bundle; an adhesive applying portion  55  configured to apply an adhesive, for example, paste or glue, to the inner sheet bundle conveyed from the stacking portion  40 ; a cover sheet binding portion  60  configured to bind a cover sheet on the inner sheet bundle having the adhesive applied thereto; a bundle attitude changing portion  64  configured to change an orientation of a sheet bundle covered with a cover sheet; a pressure portion  59  configured to press one end of the sheet bundle covered with the cover sheet at which the sheet bundle is bound with the adhesive or an edge (cut edge) of the sheet bundle at which the sheet bundle is to be cut; a cutting portion  65  configured to perform trimming cut on the edge (cut edge) of the sheet bundle covered with the cover sheet having been changed in orientation; a cutting scrap containing portion  70  configured to accommodate the cutting scrap generated during the trimming cut; and a containing stacker  67  configured to accommodate a booklet formed through the trimming cut. 
     [Configuration of Conveyance Passage] 
     Description is made of each conveyance passage for the sheets with reference to  FIG. 1 . In the casing  30 , there is provided a carry-in passage  31  having a carry-in port  29  which continues from the sheet discharge port  14  of the image forming apparatus A. The carry-in passage  31  is connected to an inner sheet conveyance passage  32  and a cover sheet conveyance passage  34  through intermediation of a passage switching member  36 . The inner sheet conveyance passage  32  is connected to a bookbinding passage  33  through intermediation of the stacking portion  40 . The cover sheet conveyance passage  34  is connected to a post-processing passage  38  of the post-processing apparatus C. The bookbinding passage  33  extends vertically through the bookbinding apparatus B in a substantially vertical direction. The cover sheet conveyance passage  34  extends horizontally through the bookbinding apparatus B in a substantially horizontal direction. Therefore, the bookbinding passage  33  and the cover sheet conveyance passage  34  cross each other (are orthogonal to each other), and the cover sheet binding portion  60  described later is arranged at the crossing part. 
     With the configuration of the conveyance passages as described above, the carry-in passage  31  receives, from the image forming apparatus A, sheets (inner sheets) having toner images formed thereon. In addition, the carry-in passage  31  receives a print sheet (cover sheet), which is to be used as a cover sheet and has a title and the like printed thereon, from the image forming apparatus A. The passage switching member  36  sets a passage to be passed by the sheet to the inner sheet conveyance passage  32  or the cover sheet conveyance passage  34 . 
     Moreover, an inserter apparatus  26  is connected to the carry-in passage  31 . The inserter apparatus  26  is configured to feed cover sheets, which are not subjected to printing in the image forming apparatus A, one after another from a sheet feeding tray  26   a  to the carry-in passage  31 . The inserter apparatus  26  includes one or a plurality of sheet feeding trays  26   a , a cover sheet feeding portion  18 , and a cover sheet feeding passage  27 . The cover sheet feeding portion  18  is configured to separate and feed one after another cover sheet stacked on the sheet feeding tray  26   a  at its distal end portion. The cover sheet feeding passage  27  is provided on a downstream side of the cover sheet feeding portion  18 . The cover sheet feeding passage  27  is connected to the carry-in passage  31  through intermediation of a passage switching member  28 . A conveyance roller pair  31   a  is arranged on the carry-in passage  31 . A conveyance roller pair  32   a  is arranged on the inner sheet conveyance passage  32 . On the bookbinding passage  33 , there are provided a grip conveyance portion  47 , the bundle attitude changing portion  64  described later, and a booklet discharging roller pair  66 . A conveyance roller pair  34   a  is arranged on the cover sheet conveyance passage  34 , and a discharge roller pair  38   a  is arranged on the post-processing passage  38 . Further, as a drive source, a drive motor (not shown) is coupled to each of the conveyance roller pair  34   a  and the discharge roller pair  38   a.    
     [Stacking Portion  40 ] 
     The stacking portion  40  is described with reference to  FIG. 2 . A stack tray  41  arranged at an inner sheet discharging port  32   x  of the inner sheet conveyance passage  32  is configured to stack and accommodate the inner sheets, which have been discharged from the inner sheet discharging port  32   x , in a bundle shape. The stack tray  41  is formed of a tray member arranged in a substantially horizontal attitude. There are arranged a forward/reverse rotation roller  42   a  and a carry-in guide  42   b  above the stack tray  41 . Then, the inner sheets having been discharged from the inner sheet discharging port  32   x  are guided to a position above the stack tray  41  by the carry-in guide  42   b , and are stacked on the stack tray  41  by the forward/reverse rotation roller  42   a . The forward/reverse rotation roller  42   a  performs forward rotation to deliver the inner sheets toward a distal end side of the stack tray  41 , and performs reverse rotation to bring a trailing edge of the inner sheets into abutment with a regulation member  43  arranged at a tray rear end (right end in  FIG. 2 ), to thereby regulate the inner sheets. A pair of sheet side alignment plates (not shown) are provided to the stack tray  41 , and the sheet side alignment plates align both side edges of the inner sheets stacked on the stack tray  41 . With such a configuration, the inner sheets having been delivered from the inner sheet conveyance passage  32  are sequentially stacked on the stack tray  41 , and then are aligned into a bundle shape. 
     [Sheet Bundle Conveyance Portion  39 ] 
     In  FIG. 2 , a sheet bundle conveyance portion  39  is arranged on the bookbinding passage  33 . The sheet bundle conveyance portion  39  includes the grip conveyance portion  47 , a folding roller pair  63 , and the booklet discharging roller pair  66 . The sheet bundle conveyance portion  39  conveys the sheet bundle from the stack tray  41  to an “adhesive applying position E”, a “cover sheet binding position F”, and a “cutting position G” in the stated order, and discharges the sheet bundle to the containing stacker  67 . 
     The grip conveyance portion  47  is formed of a pair of nip members. The grip conveyance portion  47  is configured to grip the inner sheet bundle stacked on the stack tray  41 , and rotate the inner sheet bundle by 90 degrees to change its attitude. Thus, the grip conveyance portion  47  is rotatably equipped with respect to the casing  30 . The grip conveyance portion  47  changes the inner sheet bundle stacked on the stack tray  41  from a horizontal attitude to a vertical attitude, and sets the inner sheet bundle at the adhesive applying position E so that the inner sheet bundle is to be conveyed along the bookbinding passage  33  arranged so as to extend in a substantially vertical direction. Thus, the stack tray  41  is lowered from a stacked position (solid line in  FIG. 2 ) to a delivery position (broken line in  FIG. 2 ), and delivers the sheet bundle to the grip conveyance portion  47  prepared at this delivery position. 
     The folding roller pair  63  is formed of a pair of rollers, and is configured to fold the cover sheet of the sheet bundle covered with the cover sheet simultaneously with the conveyance of the sheet bundle covered with the cover sheet from the cover sheet binding position F to the cutting position G on a downstream side. The booklet discharging roller pair  66  is also formed of a pair of rollers, and is configured to convey the sheet bundle to the containing stacker  67  on the downstream side. The bundle attitude changing portion  64  is provided between the folding roller pair  63  and the cutting position G. The bundle attitude changing portion  64  also forms a sheet bundle conveyance portion, which is described later in detail. 
     [Bundle Thickness Detection Portion] 
     The following methods are available as a method of detecting a thickness of the inner sheet bundle. A first method is a method of arranging a sheet discharging sensor Se 3  ( FIG. 2 ) at an inner sheet discharging port  32   x  of the inner sheet conveyance passage  32  to detect the thickness. The sheet discharging sensor Se 3  is configured to count the number of conveyed inner sheets, and to calculate the thickness of the inner sheet bundle from a known average thickness of the inner sheets. For example, a counter is provided to a bookbinding apparatus control CPU  85  ( FIG. 4 ), which is described later, to count sheet discharge signals from the sheet discharging sensor Se 3  during a period between a sheet discharge instruction signal and a job end signal, which are received from the image forming apparatus A, and to multiply the counted value by the thickness of an inner sheet set in advance. In this manner, the configuration is simplified when the thickness of the inner sheet bundle is calculated from the number of discharged sheets detected by the sheet discharging sensor Se 3 . However, the thickness of the inner sheet bundle detected by the first method has an approximate value obtained through calculation. 
     A second method is a method of using a slidac sensor Se 7  in abutment with an uppermost inner sheet of the inner sheets stacked on the stack tray  41 . The thickness of the inner sheet bundle is detected through detection of the position of the slidac sensor Se 7 . For example, a lever member in contact with the uppermost inner sheet is movably arranged on a stack tray in a stacking direction, and the slidac sensor Se 7  is used to detect the position of this lever member. 
     A third method is a method of using a slidac sensor Th, with the grip conveyance portion  47  being formed of a fixed gripper and a movable gripper, to detect a position at which the movable gripper is in abutment with a surface of the inner sheet. 
     The thickness of the inner sheet bundle can be detected by any one of the first method, the second method, and the third method. However, in order to detect the thickness of the inner sheet bundle with higher accuracy, it is preferred to use the second method, that is, the slidac sensor Se 7 . 
     The thickness of the inner sheet bundle detected by any one of the methods is used for subsequent control. For example, when an adhesive is applied to the inner sheet bundle by the adhesive applying portion  55  described later, an amount of the adhesive to be applied is adjusted according to a bundle thickness. 
     [Adhesive Applying Portion  55 ] 
       FIG. 3  is a view for illustrating the cover sheet binding portion  60 , the sheet bundle conveyance portion  39 , the bundle attitude changing portion  64 , the cutting portion  65 , and the cutting scrap containing portion  70  which are included in the bookbinding apparatus B. In  FIG. 1  and  FIG. 2 , the adhesive applying portion  55  is arranged at the adhesive applying position E of the bookbinding passage  33  as adhesive applying means. The adhesive applying portion  55  includes an adhesive container  56 , an applying roll  57 , and a roll rotation motor MR. The adhesive container  56  is configured to accommodate a thermally meltable adhesive. 
     An adhesive sensor  56   s  ( FIG. 2 ) configured to detect a remaining amount of the adhesive is provided in the adhesive container  56 . The adhesive sensor  56   s  serves also as a temperature sensor configured to detect a temperature of the adhesive. The adhesive sensor  56   s  is configured to detect a temperature of the liquefied adhesive in the adhesive container  56 . The adhesive sensor  56   s  is also configured to detect a remaining amount of the adhesive based on a difference in temperature between a part that is soaked in the adhesive and a part that is not soaked in the adhesive. Then, the adhesive container  56  is caused to reciprocate along the sheet bundle from a home position with a predetermined stroke, and in the process of the reciprocating movement, the adhesive is applied to the edge (one end) of the sheet bundle by the applying roll  57  in the adhesive container  56 . The applying roll  57  is formed of a heat-resistant porous material, and is configured to allow glue to be impregnated thereinto to thereby form a layer of the glue on a periphery of the roll. 
     [Cover Sheet Binding Portion  60 ] 
     The cover sheet binding portion  60  is arranged at the cover sheet binding position F on the bookbinding passage  33 . As illustrated in  FIG. 3 , the cover sheet binding portion  60  is formed of an abutment plate  61 , folding plates  62  ( 62   a  and  62   b ), and a folding roller pair  63 . The cover sheet conveyance passage  34  is arranged at the cover sheet binding position F ( FIG. 2 ), and a cover sheet is fed from the image forming apparatus A or the inserter apparatus  26 . 
     The abutment plate  61  is a plate-shaped member configured to hold the cover sheet from the back (support the cover sheet). The abutment plate  61  supports the cover sheet when the cover sheet delivered from the cover sheet conveyance passage  34  and the inner sheet bundle delivered from the bookbinding passage  33  are joined to each other. The abutment plate  61  also has a function of cooling a bound portion of the sheet bundle to which the cover sheet has been bonded. The abutment plate  61  is arranged so as to be movable along the bookbinding passage  33 . When the sheet bundle covered with the cover sheet moves to the cutting position G on the downstream side, the abutment plate  61  is caused to retreat from a path of the sheet bundle covered with the cover sheet. 
     The folding plates  62  are arranged on upstream of the abutment plate  61 , and are configured to fold the cover sheet supported by the abutment plate  61 . Thus, the folding plates  62  are arranged in a pair ( 62   a  and  62   b ) on right and left sides of the bookbinding passage  33 , and are configured to be able to approach and separate from each other. The right and left folding plates  62   a  and  62   b  are each coupled to an actuating motor  62 M serving as a drive source through intermediation of a rack gear  62   r  and a transmission pinion  62   p.    
     Thus, when the right and left actuating motors  62 M are rotated by the same amount, pressure surfaces of the folding plates  62   a  and  62   b  bend a bound portion of the cover sheet to form a spine of a book. The cover sheet conveyance passage  34  illustrated in  FIG. 3  includes the conveyance roller pair  34   a . In addition, upper guides  34   g  forming the cover sheet conveyance passage  34  are caused to swing in an up-and-down direction together with the conveyance roller pair  34   a  about rotary shafts  34   h  to open and close an upper side of the bookbinding passage  33 . 
     The cover sheet fed to the cover sheet conveyance passage  34  by the abutment plate  61  and the folding plates  62  is supported by the abutment plate  61 . The inner sheet bundle delivered from the bookbinding passage  33  by the grip conveyance portion  47  is brought into abutment on the cover sheet to be joined to the cover sheet. After this joining, the folding plates  62  are brought closer to each other from separate positions illustrated in  FIG. 3 . Then, the cover sheet is folded so as to sandwich the inner sheet bundle to form a spine of a book. The folding roller pair  63  is arranged on the downstream side of the abutment plate  61 . The folding roller pair  63  is a pair of rollers held in pressure contact with each other. Although not shown, one of the rollers is moved in a direction perpendicular to a conveyance direction according to the thickness of the sheet bundle. 
     The bookbinding apparatus B according to this embodiment has a feature in that, at the cutting position G, the sheet bundle covered with the cover sheet is pressed against a receiving member  58  by a pressing member  59   y . Its configuration and operation are described later. 
     [Sheet Bundle Cutting Apparatus D] 
     A sheet bundle cutting apparatus D illustrated in  FIG. 1  is configured to cut the cut edge of the sheet bundle covered with a cover sheet. The sheet bundle cutting apparatus D includes the bundle attitude changing portion  64 , the pressure portion  59 , and the cutting portion  65 . 
     [Bundle Attitude Changing Portion  64 ] 
     The bundle attitude changing portion  64  is described with reference to  FIG. 3 ,  FIG. 9A , and  FIG. 9B . The bundle attitude changing portion  64  serving as moving/rotating means for changing the orientation of the sheet bundle and the cutting portion  65  serving as cutting means for cutting a peripheral edge of the sheet bundle are arranged on the downstream side of the folding roller pair  63 . The bundle attitude changing portion  64  is configured to feed the sheet bundle having been subjected to the joining of the cover sheet at the cover sheet binding position F to the cutting position G on the downstream side in an attitude in a predetermined orientation. The cutting portion  65  is configured to cut an end portion of the sheet bundle at the cutting position G to adjust a shape of its cross section. 
     The bundle attitude changing portion  64  includes rotation tables  64   a  and  64   b . The rotation tables  64   a  and  64   b  are configured to sandwich and hold the sheet bundle covered with the cover sheet delivered from the folding roller pair  63  in a thickness direction. The rotation tables  64   a  and  64   b  are configured to subsequently rotate the sheet bundle covered with the cover sheet about a normal direction of the surface of the sheet bundle serving as a rotary axis. As illustrated in  FIG. 3 , the rotation tables  64   a  and  64   b  are provided on a unit frame  64   x . The unit frame  64   x  can be raised and lowered with respect to the casing  30 . 
     The unit frame  64   x  is configured to rotatably support each of a pair of rotation tables  64   a  and  64   b  with the bookbinding passage  33  interposed therebetween. The rotation table  64   b  can move in a sheet bundle thickness direction (direction perpendicular to the bookbinding passage  33 ). The rotation tables  64   a  and  64   b  include motors Mt 1  and Mt 2  as drive sources for changing the attitude of the sheet bundle in the bookbinding passage  33 . In addition, the rotation table  64   b  includes a grip motor Mg for movement in a horizontal direction illustrated in  FIG. 3 . 
     The sheet bundle C 3  covered with the cover sheet guided into the bookbinding passage  33  is conveyed by the folding roller pair  63  with a spine C 3 B bound with the adhesive facing down. Then, the sheet bundle C 3  covered with the cover sheet is held by a pair of left and right rotation tables  64   a  and  64   b , and has the attitude changed by the motors Mt 1  and Mt 2 . 
     When the peripheral edges in three directions other than the spine are cut (subjected to the trimming cut), the sheet bundle C 3  covered with the cover sheet is set to have cutting lines L 1 , L 2 , and L 3  illustrated in  FIG. 9A  at the cutting position G, and the cutting portion  65  cuts the sheet bundle C 3  covered with the cover sheet along each of the cutting lines L 1 , L 2 , and L 3 . In this embodiment, cutting lines for cutting the cutting scraps including parts of the spine C 3 B of the sheet bundle C 3  covered with the cover sheet are set as L 1  and L 2 , and a cutting line for cutting the opposite side of the spine C 3 B is set as L 3 . 
     In addition, a grip sensor (not shown) is provided to the rotation table  64   b  on a movable side. The rotation tables  64   a  and  64   b  start to be rotated after the grip sensor has detected that the sheet bundle C 3  covered with the cover sheet is firmly held. Then, the unit frame  64   x  moves the sheet bundle along the bookbinding passage  33  by an elevation motor MS. 
     At a time of three-way trimming, the sheet bundle C 3  covered with the cover sheet is repeatedly set at the cutting position G by the bundle attitude changing portion  64  and cut by the cutting portion  65  in order of the cutting lines L 1 , L 2 , and L 3 . At a time of two-way trimming, the sheet bundle C 3  covered with the cover sheet is repeatedly set at the cutting position G and cut in order of the cutting lines L 1  and L 2 . At a time of one-way trimming, the sheet bundle C 3  covered with the cover sheet has the cutting line L 3  set at the cutting position G and cut. 
     [Pressure Portion  59 ] 
     As illustrated in  FIG. 2  and  FIG. 3 , the pressure portion  59  serving as pressure means includes a cut edge pressing unit  59   b  and the receiving member  58 . The cut edge pressing unit  59   b  includes the pressing member  59   y  and a motor (not shown) configured to cause the pressing member  59   y  to approach and separate from the receiving member  58 . The pressing member  59   y  is moved by the motor (not shown) to press the sheet bundle C 3  covered with the cover sheet against the receiving member  58  from its thickness direction. In other words, the pressure portion  59  presses the sheet bundle C 3  covered with the cover sheet in its thickness direction while sandwiching a first surface and a second surface of the sheet bundle C 3  covered with the cover sheet by the pressing member  59   y  and the receiving member  58 . The receiving member  58  is a plate-shaped member and has a length in the up-and-down direction so as to be opposed to the pressing member  59   y  and a cutting blade  65   x  described later. The receiving member  58  is formed so as to withstand a pressing force applied from the pressing member  59   y  and the cutting blade  65   x.    
     The pressure portion  59  configured in this manner uses the pressing member  59   y  and the receiving member  58  to press one end (spine) of the sheet bundle C 3  covered with the cover sheet at which the sheet bundle C 3  is bound with the adhesive or the edge (cut edge) of the sheet bundle C 3  covered with the cover sheet at which the sheet bundle is to be cut. 
     [Cutting Portion  65 ] 
     As illustrated in  FIG. 2  and  FIG. 3 , the cutting portion  65  serving as the cutting means includes the cut edge pressing unit  59   b , the cutting blade unit  65   a , and the receiving member  58 . The cut edge pressing unit  59   b  and the receiving member  58  have already been described in the section regarding the pressure portion  59 , and hence description thereof is omitted. The cutting blade unit  65   a  includes the cutting blade  65   x  and a cutter motor MC. The cutting blade  65   x  has a flat blade shape. The cutter motor MC is configured to cause the cutting blade  65   x  to approach and separate from the receiving member  58 . The cutting portion  65  uses the pressing member  59   y  to cause the edge (cut edge) of the sheet bundle covered with the cover sheet at which the sheet bundle is to be cut to be pressed against the receiving member  58 . After that, the cutting portion  65  uses the cutting blade  65   x  to cut and trim a predetermined amount of the peripheral edge (cut edge) excluding the spine of the sheet bundle covered with the cover sheet. Then, the peripheral edge of the cut sheet bundle is discharged as a cutting scrap. 
     The booklet discharging roller pair  66  and the containing stacker  67  are arranged on the downstream side of the cutting position G. As illustrated in  FIG. 3 , the containing stacker  67  is configured to accommodate the sheet bundle in an upright attitude. The booklet discharging roller pair  66  is arranged on the downstream side of the cutting position G, and is configured to convey the sheet bundle to the containing stacker  67 . The booklet discharging roller pair  66  is formed of a pair of rollers  66   a  and  66   b . The roller  66   b  is configured to move in a sheet width direction according to the thickness of the sheet bundle to change a position for nipping the sheet bundle. 
     The containing stacker  67  is also enabled to be pulled out from the casing  30 . The user can pull out the containing stacker  67  toward a front side of the image forming apparatus A (front side of the drawing sheet of  FIG. 1 ) to take out the sheet bundle from above the containing stacker  67 . The sheet bundle full sensor  67 Sf is configured to detect a fully-filled state of sheet bundles contained in the containing stacker  67  and urge an operator to remove the sheet bundles. 
     [Cutting Scrap Containing Portion  70 ] 
     The cutting scrap containing portion  70  serving as a containing means for containing a cutting scrap is provided below the cutting position G in parallel with the containing stacker  67 . The cutting scrap containing portion  70  includes a cutting scrap container  68 , a sweeper portion  69 , and a full sensor  68 Sf. The cutting scrap container  68  is arranged in parallel with the containing stacker  67 . The cutting scrap container  68  is configured to accommodate a cutting scrap cut by the cutting blade  65   x . The sweeper portion  69  is provided immediately below the cutting position G. The sweeper portion  69  is configured to swing along a left-and-right direction indicated by the solid line and the broken line in  FIG. 2  by a drive motor (not shown). The sweeper portion  69  is also configured to guide the cutting scrap to the cutting scrap container  68  while waiting at a position indicated by the solid line immediately below the cutting position G when the sheet bundle is cut, and after the sheet bundle is cut, retreat from the cutting position G to a position indicated by the broken line to guide the sheet bundle to the containing stacker  67 . In addition, the full sensor  68 Sf configured to detect a containing amount of cutting scraps contained inside is arranged for the cutting scrap container  68 . 
     The cutting scrap C 3 W contained in the cutting scrap containing portion  70  is described with reference to  FIG. 10A  and  FIG. 10B . In  FIG. 10A , the cutting scrap C 3 W cut from the sheet bundle C 3  covered with the cover sheet by the cutting line L 1  is bound with the adhesive BN applied to a spine BW side of the cutting scrap. As illustrated in  FIG. 10B , the unbound side of the cutting scrap C 3 W is adversely opened. When the cutting scrap C 3 W in a spreading state illustrated in  FIG. 10B  is discharged to the cutting scrap containing portion  70 , there is a fear in that the cutting scrap C 3 W may be caught at some midpoint of a discharging passage or may become bulky inside the cutting scrap container  68  to deteriorate a containing efficiency. 
     [Post-Processing Apparatus C] 
     As illustrated in  FIG. 1 , the post-processing apparatus C is connected to the bookbinding apparatus B. The post-processing apparatus C includes the post-processing passage  38  continuing from the cover sheet conveyance passage  34 . At least one post-processing device (not shown) such as a stapling unit, a punching unit, or a stamp unit is arranged on the post-processing passage  38 . Accordingly, the post-processing apparatus C receives, through the cover sheet conveyance passage  34 , sheets having been subjected to image formation, which have been conveyed from the image forming apparatus A, and performs at least one post-processing such as stapling, punching, or stamping on the sheets having been subjected to image formation. Then, the post-processing apparatus C conveys sheets having been subjected to image formation to a discharge tray  37  by the discharge roller pair  38   a . The post-processing apparatus C can also discharge the sheets having been subjected to the image formation, which have been conveyed from the image forming apparatus A and are not required to be subjected to such post-processing, to the discharge tray  37  without performing the post-processing. 
     [Bookbinding Apparatus Control CPU  85 ] 
       FIG. 4  is a control block diagram for illustrating the image forming apparatus A and the bookbinding apparatus B. An image forming apparatus control CPU  83  of the image forming apparatus A is connected to an input portion (control panel)  82  and a mode setting portion  84 . The bookbinding apparatus control CPU  85  serving as control means of the bookbinding apparatus B calls a bookbinding processing execution program from the ROM  87  and executes each processing step for the bookbinding passage  33  ( FIG. 1 ). The image forming apparatus control CPU  83  and the bookbinding apparatus control CPU  85  may be integrated to be provided in any one of the image forming apparatus A and the bookbinding apparatus B. 
     The bookbinding apparatus control CPU  85  is configured to receive a post-processing mode instruction signal, a job end signal, sheet size information, other information relating to bookbinding, and a command signal from the image forming apparatus control CPU  83 . The bookbinding apparatus control CPU  85  is also configured to transmit information on a bookbinding operation state to the image forming apparatus control CPU  83 . A sheet sensor (not shown) configured to detect a sheet (sheet bundle) being conveyed is arranged in each of the carry-in passage  31  ( FIG. 1 ), the bookbinding passage  33 , and the cover sheet conveyance passage  34 . 
     The bookbinding apparatus control CPU  85  is configured to receive not only various signals from the image forming apparatus control CPU  83  but also detection signals from the respective sheet sensors to control a “stacking portion controller  85   a ”, an “adhesive applying portion controller  85   b ”, a “cover sheet binding portion controller  85   c ”, a “bundle attitude changing portion controller  85   d ”, a “pressure portion controller  85   e ”, a “cutting portion controller  85   f ”, a “cutting scrap containing portion controller  85   g ”, and a “containing stacker control  85   h”.    
     [Pressurization Operation of Cover Sheet Binding Portion  60  at Cover Sheet Binding Position F] 
     Next, an operation of pressing, by the cover sheet binding portion  60 , the inner sheet bundle from the thickness direction at the cover sheet binding position F is described with reference to a flowchart illustrated in  FIG. 5 . 
     When the job end signal is received from the image forming apparatus control CPU  83  (Step S 501 ), the bookbinding apparatus control CPU  85  detects the thickness of the inner sheet bundle based on the detection signal received from the slidac sensor Se 7  or Th ( FIG. 2 ) (Step S 502 ). The bookbinding apparatus control CPU  85  stores a detected value in the RAM  86  ( FIG. 4 ) (Step S 502 ). Subsequently, the inner sheet bundle aligned as a copy on the stack tray  41  is changed from the horizontal attitude to the vertical attitude, and is moved along the bookbinding passage  33  to reach the adhesive applying position E on the downstream side (Step S 503 ). 
     The bookbinding apparatus control CPU  85  conveys the cover sheet from the cover sheet conveyance passage  34  ( FIG. 2 ) to the cover sheet binding position F in response to the sheet bundle being set at the adhesive applying position E (Step S 504 ). The cover sheet may be fed from the image forming apparatus A with an image having been formed thereon, or may be fed from the inserter apparatus  26  without an image having been formed thereon. When the cover sheet is fed from the inserter apparatus  26  ( FIG. 1 ), the bookbinding apparatus control CPU  85  actuates the sheet supply portion (not shown) to separate the cover sheets from the sheet feeding tray  26   a  ( FIG. 1 ) one by one to feed each cover sheet to the cover sheet feeding passage  27 . 
     The cover sheet delivered to the cover sheet feeding passage  27  is conveyed to the carry-in passage  31  by a conveyance roller pair  27   a . The bookbinding apparatus control CPU  85  brings the passage switching member  28  to a position in a state illustrated in  FIG. 1 , and guides the cover sheet to the cover sheet conveyance passage  34 . The cover sheet conveyance passage  34  is provided with a registration mechanism  34   b  for correcting the attitude of the cover sheet. The cover sheet having the attitude corrected by the registration mechanism  34   b  is conveyed from the registration mechanism  34   b  by a predetermined distance, and reaches the cover sheet binding position F to be brought to the standstill. Subsequently to the cover sheet feed setting, the bookbinding apparatus control CPU  85  drives the adhesive applying portion  55  to apply the adhesive to the inner sheet bundle set at the adhesive applying position E (Step S 505 ). The adhesive container  56  provided with the applying roll  57  is moved along a lower end edge of the inner sheet bundle, and the adhesive impregnated on a roll surface of the applying roll  57  is applied to one end of the inner sheet bundle. 
     After the adhesive applying portion  55  ( FIG. 2 ) has completed an adhesive applying operation, the bookbinding apparatus control CPU  85  causes the grip conveyance portion  47  to transfer the inner sheet bundle to the cover sheet binding position F on the downstream side. The cover sheet has already been set at this position, and hence the cover sheet is supported by the abutment plate  61  to be joined to the inner sheet bundle. Subsequently, with the cover sheet and the inner sheet bundle being in abutment with each other, the folding plates  62  push the cover sheet to cause the cover sheet to be bonded to the inner sheet bundle (Step S 506 ). Through the above-mentioned steps, a cover sheet is attached to an inner sheet bundle to form a sheet bundle covered with a cover sheet. 
     Subsequently, the bookbinding apparatus control CPU  85  determines whether or not to perform the trimming cut. At the same time, the bookbinding apparatus control CPU  85  sets a cooling time required for the adhesive applied to the inner sheet bundle to become solid (solidify) (Step S 507 ). Numerical values are merely reference numerical values, and do not limit the present invention. 
     This cooling time is set according to a thickness T of the inner sheet bundle. For example, when the thickness of the inner sheet bundle is less than 10 mm, the cooling time is set to about 30 seconds. When the thickness of the inner sheet bundle exceeds 10 mm and is equal to or less than 20 mm, the cooling time is set to about 40 seconds. When the thickness of the inner sheet bundle exceeds 20 mm and is equal to or less than 30 mm, the cooling time is set to about 50 seconds. When the thickness of the inner sheet bundle exceeds 30 mm, the cooling time is set to about 60 seconds. The bookbinding apparatus control CPU  85  reads a data table, which is stored in the RAM  86  in advance based on properties of the adhesive, to set this cooling time according to the bundle thickness of the sheet bundle to be bound. 
     The end of a cover sheet binding operation is detected by position sensors Se 5  and Se 6  ( FIG. 2 ) of the folding plates  62   a  and  62   b . The position sensors Se 5  and Se 6  detect that the folding plates  62   a  and  62   b  have been separated from each other after having approached each other and have returned to a waiting position, and transmit an operation completion signal. The bookbinding apparatus control CPU  85  determines that the cover sheet binding operation has been completed by receiving the operation completion signal. The bookbinding apparatus control CPU  85  waits until the cooling time set in Step S 507  has elapsed after receiving the operation completion signal. When the cooling time has elapsed (YES in Step S 508 ), the bookbinding apparatus control CPU  85  again brings the folding plates  62   a  and  62   b  closer to the sheet bundle covered with the cover sheet to press the sheet bundle covered with the cover sheet from both sides in the thickness direction (Step S 511 ). After that, the image forming apparatus control CPU  83  separates the folding plates  62   a  and  62   b  from each other, causes the abutment plate  61  to retreat from the bookbinding passage  33 , and at the same time, causes the grip conveyance portion  47  to release the grip of the inner sheet bundle. The sheet bundle covered with the cover sheet is conveyed to the cutting position by the folding roller pair  63 . The processing of Step S 511  is not always required to be performed. 
     The sheet bundle covered with the cover sheet falls downward from the cover sheet binding position F to be nipped by the folding roller pair  63 . The bookbinding apparatus control CPU  85  rotates the folding roller pair  63  in a discharging direction to deliver the sheet bundle covered with the cover sheet toward the downstream side. 
     [Control of Cover Sheet Binding Operation Based on Property Information of Cover Sheet] 
       FIG. 6  is a diagram for illustrating a control flow in the case of controlling an operation of pressing the cover sheet based on property information of a sheet to be used as the cover sheet. Step S 501  to Step S 508 , Step S 511 , and Step S 512  illustrated in  FIG. 6  are the same as Step S 501  to Step S 508 , Step S 511 , and Step S 512  illustrated in  FIG. 5 , and hence description thereof is omitted. 
     In Step S 509 , the bookbinding apparatus control CPU  85  sets a basis weight threshold value. The bookbinding apparatus control CPU  85  reads the data table stored in the RAM  86  ( FIG. 4 ) in advance to set the basis weight threshold value. 
     Then, the bookbinding apparatus control CPU  85  compares a basis weight serving as the sheet information of the cover sheet, which has been input to the input portion  82  ( FIG. 4 ) of the image forming apparatus A by the user, against the basis weight threshold value (Step S 510 ). When the basis weight of the cover sheet is equal to or more than the basis weight threshold value (YES in Step S 510 ), the bookbinding apparatus control CPU  85  performs the operation of pressing the cover sheet. When the basis weight of the cover sheet is less than the basis weight threshold value (NO in Step S 510 ), the bookbinding apparatus control CPU  85  rotates a folding roller pair without performing the operation of pressing the cover sheet (Step S 512 ). 
     The reason why the operation of pressing the cover sheet is not performed when the basis weight of the cover sheet is less than the basis weight threshold value is that a sufficient crease can be created on the cover sheet only by the folding roller pair. 
     In another case, a plurality of basis weight threshold values may be provided to change the number of pressing operations according to the basis weight of the sheet of the cover sheet. As the basis weight of the sheet of the cover sheet increases, it becomes difficult to create a crease. In view of this, the bookbinding apparatus control CPU  85  increases the number of pressing operations performed by the folding plates  62   a  and  62   b  as the basis weight of the sheet of the cover sheet increases. This enables a sufficient crease to be created when a sheet having a large basis weight is used as the cover sheet. 
     [Pressing Operation of Pressing Member  59   y  at Cutting Position G] 
     The pressing operation of pressing the sheet bundle covered with the cover sheet from the thickness direction is described with reference to the flowcharts illustrated in  FIG. 3  and  FIG. 7  and to  FIG. 9A . Specifically, the pressing operation is an operation of applying pressure while sandwiching the sheet bundle covered with the cover sheet between the pressing member  59   y  and the receiving member  58  at the cutting position G. 
     The bookbinding apparatus control CPU  85  rotates the folding roller pair  63  in the sheet discharging direction in a state in which the sheet bundle covered with the cover sheet is nipped by the folding roller pair  63 , and delivers the sheet bundle covered with the cover sheet toward the downstream side (Step S 701 ). 
     The bookbinding apparatus control CPU  85  rotates the folding roller pair  63 , and at the same time, moves the cutting blade  65   x  from a waiting position Wp to a cutting completion position Cp (Step S 702 ). Then, the sheet bundle covered with the cover sheet falls to be moved onto the cutting blade  65   x  (Step S 703 ). In the sheet bundle covered with the cover sheet, the edge bound with the adhesive is brought into abutment with the cutting blade  65   x  to be received by the cutting blade  65   x . At this time, the attitude of the sheet bundle C 3  covered with the cover sheet is defined by a state in which the edge (spine) bound with the adhesive follows an extending direction of the cutting blade  65   x . Subsequently, when the cutting of the cut edge is set (set to the trimming cut) (YES in Step S 704 ), the bookbinding apparatus control CPU  85  causes the sheet bundle covered with the cover sheet to be nipped by the rotation tables  64   a  and  64   b  of the bundle attitude changing portion  64  from the thickness direction (Step S 705 ). 
     Then, the bookbinding apparatus control CPU  85  rotates the rotation tables  64   a  and  64   b  of the bundle attitude changing portion  64 , which are nipping the sheet bundle covered with the cover sheet, to rotate the sheet bundle covered with the cover sheet in a predetermined direction (Step S 706 ). The bookbinding apparatus control CPU  85  first rotates the rotation tables  64   a  and  64   b  so that the side of the cutting line L 1  of the sheet bundle C 3  covered with the cover sheet faces the cutting position G. 
     Subsequently, the bookbinding apparatus control CPU  85  determines whether or not the spine C 3 B is included in a cutting area of the sheet bundle C 3  covered with the cover sheet (Step S 707 ). In  FIG. 9A , when the cutting is performed along the cutting line L 1  and when the cutting is performed along the cutting line L 2 , the spine C 3 B is included in the cutting area. Meanwhile, when the cutting is performed by the cutting line L 3 , the spine C 3 B is not included in the cutting area. 
     When the cutting area includes the spine C 3 B (Yes in Step S 707 ), the procedure advances to Step S 708 , and when the cutting area does not include the spine C 3 B (No in Step S 707 ), the procedure advances to Step S 710 . 
     When the cutting area includes the spine C 3 B (Yes in Step S 707 ), the bookbinding apparatus control CPU  85  drives the elevation motor MS to move the sheet bundle C 3  covered with the cover sheet and presses a pressed area C 3 P (Step S 708 ). That is, the bookbinding apparatus control CPU  85  uses the pressure portion  59  to press connection areas connected to the spine C 3 B, which are respectively provided on the first surface and the second surface of the sheet bundle C 3  covered with the cover sheet. In other words, the pressure portion  59  presses portions (connection areas) that are a part of the first surface and a part of the second surface and are continuous with the spine. Then, those connection areas serve as the pressed area C 3 P. A specific description thereof is given. 
     First, the bookbinding apparatus control CPU  85  moves the sheet bundle C 3  covered with the cover sheet to a position at which the pressed area C 3 P is to be pressed by the pressing member  59   y . This position alignment is set based on a signal received from a sheet lower end detecting sensor (not shown). After a lower end detecting sensor has detected a leading end of the sheet bundle covered with the cover sheet in the gravity direction, the bookbinding apparatus control CPU  85  drives the elevation motor MS for a predetermined time. Subsequently, the bookbinding apparatus control CPU  85  drives the cut edge pressing unit  59   b  to press the pressed area C 3 P with a force of from about 2 kN to about 4 kN. 
     The pressed area C 3 P to be pressed in Step S 708  is set to include the spine BW of the cutting scrap to be cut in a later step in the spine C 3 B of the sheet bundle C 3  covered with the cover sheet. In other words, the pressed area C 3 P is set to connect to the spine BW to be the cutting scrap in the spine C 3 B. 
     Subsequently, the bookbinding apparatus control CPU  85  releases the pressure being applied to the sheet bundle C 3  covered with the cover sheet by the cut edge pressing unit  59   b  (Step S 709 ). 
     Subsequently, the bookbinding apparatus control CPU  85  drives to rotate the elevation motor MS to move the sheet bundle C 3  covered with the cover sheet, and to align the cutting line L 1  with the cutting position G of the cutting portion  65  (Step S 710 ). 
     After that, the bookbinding apparatus control CPU  85  uses the cut edge pressing unit  59   b  to press an area other than the cutting area of the sheet bundle C 3  covered with the cover sheet, and uses a cutter motor Mc to move the cutting blade unit  65   a  from the waiting position Wp to the cutting completion position Cp. When the cutting blade unit  65   a  has moved to the cutting completion position Cp, the cutting scrap C 3 W is separated from the sheet bundle covered with the cover sheet (Step S 711 ). That is, the bookbinding apparatus control CPU  85  uses the pressure portion  59  to press the pressed area C 3 P, and then uses the cutting portion  65  to cut the sheet bundle C 3  covered with the cover sheet so that the pressed area C 3 P is included in the cutting scrap C 3 W. At this time, the cutting portion  65  is used to cut the sheet bundle C 3  covered with the cover sheet while causing the pressure portion  59  to press the area other than the area to be the cutting scrap of the sheet bundle C 3  covered with the cover sheet. 
     When the other edge of the sheet bundle covered with the cover sheet is also cut (NO in Step S 712 ), the procedure returns to Step S 706 , and the bookbinding apparatus control CPU  85  rotates the sheet bundle C 3  covered with the cover sheet so that a cutting line that has not been cut yet faces the cutting position G. When the cutting has been finished for all the cutting lines (YES in Step S 712 ), the sheet bundle covered with the cover sheet becomes a booklet. Then, the bookbinding apparatus control CPU  85  releases the holding of the booklet by the bundle attitude changing portion  64  (Step S 713 ). The booklet falls on the booklet discharging roller pair  66 , and is conveyed by the booklet discharging roller pair  66  being driven (Step S 714 ) so as to be contained in the containing stacker  67  (Step S 714 ). 
     When the trimming cut is not performed (No in Step S 704 ), the sheet bundle covered with the cover sheet is conveyed as it is (Step S 714 ) to be contained in the containing stacker  67  (Step S 715 ). 
     In this manner, in addition to the above-mentioned pressing performed by the folding plates  62  ( 62   r  and  62   r ) (processing of Step S 511  illustrated in  FIG. 5 ), the pressed area C 3 P is pressed by the cut edge pressing unit  59   b  also before the sheet bundle C 3  covered with the cover sheet is cut. This prevents the cover sheet of the cutting scrap C 3 W from being opened with a lapse of time after the binding is performed. Then, it is possible to prevent the cutting scrap C 3 W from being caught at some midpoint of falling into the cutting scrap container  68  or becoming bulky inside the cutting scrap container  68  to deteriorate the containing efficiency of the cutting scrap C 3 W. 
     Second Embodiment 
     A second embodiment of the present invention is described. A basic configuration of the second embodiment is the same as that of the first embodiment, and hence the following description of the second embodiment is given mainly to a part different from the first embodiment. 
     The second embodiment of the present invention is configured so that a pressed area of the sheet bundle C 3  covered with the cover sheet is pressed by one operation. A pressing operation to be performed in the second embodiment is described with reference to a flowchart illustrated in  FIG. 8  and to  FIG. 9B ,  FIG. 10A , and  FIG. 10B . 
     When trimming is to be performed (Yes in Step S 804 ), the same operations as Step  701  to Step  705  illustrated in  FIG. 7  are performed in Step S 801  to Step S 805 . 
     Subsequently, the bookbinding apparatus control CPU  85  presses the sheet bundle C 3  covered with the cover sheet, which is held by the rotation tables  64   a  and  64   b  of the bundle attitude changing portion  64 , by sandwiching the sheet bundle C 3  by the pressing member  59   y  and the receiving member  58  (Step S 806 ). At this time, the sheet bundle C 3  covered with the cover sheet is in a state in which the spine C 3 B bound with the adhesive and the cutting blade  65   x  are in abutment with each other. The pressing member  59   y  and the receiving member  58  have a length sufficient to press the entire spine C 3 B, and press the pressed area C 3 P of the sheet bundle C 3  covered with the cover sheet in  FIG. 9B . The pressed area C 3 P illustrated in  FIG. 9B  includes the spine BW of the cutting scrap to be cut at the cutting lines L 1  and L 2  in a later step. In other words, the cutting scrap and a remaining part of the sheet bundle C 3  covered with the cover sheet from which the cutting scrap has been removed each include the pressed area C 3 P. 
     Depending on a positional relationship between the cutting blade  65   x  and the pressing member  59   y , the spine BW of the cutting scrap may not be included in the pressed area C 3 P. In that case, the bookbinding apparatus control CPU  85  presses the pressed area C 3 P after causing the bundle attitude changing portion  64  to move the position of the sheet bundle C 3  covered with the cover sheet so that the spine BW of the cutting scrap is included in the pressed area C 3 P. 
     The subsequent steps are the same as those in the first embodiment. That is, the bookbinding apparatus control CPU  85  releases the pressure on the sheet bundle C 3  covered with the cover sheet (Step S 807 ), rotates the edge of the sheet bundle C 3  covered with the cover sheet at which the sheet bundle C 3  is to be cut toward the cutting portion  65  (Step S 808 ), and moves the sheet bundle C 3  covered with the cover sheet to the cutting position (Step S 809 ) to perform the cutting (Step S 810 ). When the cutting of required parts has been finished (Step S 811 ), the completed booklet is contained in a containing stacker (Step S 812 , Step S 813 , and Step S 814 ). 
     According to this embodiment, the pressed area C 3 P of the sheet bundle C 3  covered with the cover sheet is pressed by one pressing operation, and hence a time required for the trimming can be shortened in suppressing the opening of the cutting scrap C 3 W. 
     Other Embodiments 
     In the first embodiment and the second embodiment, modes in which the pressed area C 3 P is differently arranged in the sheet bundle C 3  covered with the cover sheet have been described, but embodiments of the present invention are not limited thereto. The effects of the present invention can be produced by using the cutting means to cut the cutting scrap including the spine of the sheet bundle covered with the cover sheet after the control means has caused the pressure means to press only an overlapping area of the pressed area in the first embodiment and the pressed area in the second embodiment. 
     Further, when the bookbinding apparatus control CPU  85  causes the pressure portion  59  to press the cutting area of the sheet bundle, a pressure force may be changed according to the thickness of the sheet bundle. In this case, the pressure force of the pressure portion  59  is increased as the sheet bundle becomes thicker. That is, the bookbinding apparatus control CPU  85  sets a force to be applied by the pressure portion  59  to press the sheet bundle so that the force to be applied when the thickness of the sheet bundle is large becomes larger than the force to be applied when the thickness of the sheet bundle is small. Accordingly, it is possible to prevent the cutting scrap from being opened irrespective of the thickness of the sheet bundle. 
     The present invention is not limited to the embodiments described above, and various changes and modifications can be made without departing from the spirit and scope of the present invention. The following claims are appended hereto in order to make the scope of the present invention public. 
     The present application claims priority based on Japanese Patent Application No. 2018-081833 filed on Apr. 20, 2018 and Japanese Patent Application No. 2019-075956 filed on Apr. 11, 2019, and the entire contents thereof are incorporated herein by reference. 
     REFERENCE SIGNS LIST 
     A: image forming apparatus, B: bookbinding apparatus, C: post-processing apparatus, D: sheet bundle cutting apparatus, E: adhesive applying position, F: cover sheet binding position, G: cutting position, J: image forming system, C 1 : inner sheet, C 2 : cover sheet, C 3 : sheet bundle covered with cover sheet, C 3 B: spine of sheet bundle covered with cover sheet, C 3 P: pressed area, C 3 W: cutting scrap, BN: adhesive, BW: spine of cutting scrap,  32 : inner sheet conveyance passage,  33 : bookbinding passage,  34 : cover sheet conveyance passage,  55 : adhesive applying portion (adhesive applying means),  58 : receiving member,  59 : pressure portion (pressure means),  59   y : pressing member,  60 : cover sheet binding portion,  64 : bundle attitude changing portion (moving/rotating means),  64   a ,  64   b : rotation table (holding means, rotating means),  64   x : unit frame (moving means),  65 : cutting portion (cutting means),  65   x : cutting blade (position alignment means),  66 : booklet discharging roller pair,  67 : containing stacker,  68 : cutting scrap container,  69 : sweeper portion,  70 : cutting scrap containing portion (cutting scrap containing means),  83 : image forming apparatus control CPU,  85 : bookbinding apparatus control CPU (control means)