Binding device, binding member, and image forming system

Abstract

To restrict misalignment and leaning of teeth in comparison with having, as upper teeth and lower teeth, only teeth rows where recording material bundles are partly deformed for performing binding processing of the recording material bundles.SOLUTION: A binding device includes: upper teeth having a teeth row for forming unevenness on a recording material bundle; lower teeth having a teeth row for forming unevenness on the recording material bundle, and making a pair with the upper teeth; and a holding part for holding the recording material bundles at a different place from a place having a binding function of the upper teeth and the lower teeth when performing binding processing by the upper teeth and the lower teeth.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a binding device, a binding member, and an image forming system. [Background technology]

[0002] Patent document 1 describes a paper processing device in which at least some of the ends of the toothed portions of the binding means are rounded, so that when the toothed portions are engaged with each other, the paper does not wrinkle or break, or in other words, it does not tear, and this prevents a decrease in binding strength. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-121865 A Summary of the Invention [Problem to be solved by the invention]

[0004] One binding device that performs binding processing without using staples such as staples has upper and lower teeth that press against a stack of recording materials to partially deform the stack of recording materials, thereby binding the stack of recording materials. When the upper and lower teeth are used to bind the recording material stack, the stack is partially deformed, and if the recording material breaks during this process, the teeth may become misaligned or tilted in the direction in which they are aligned, reducing the binding force of the recording material stack. In particular, in stacks of recording materials with a large number of sheets, such as six or more, the teeth are likely to become misaligned or tilted, and a reduction in the binding force of the recording material stack may become a problem. The present invention aims to suppress misalignment and inclination of the teeth compared to a case in which the upper and lower teeth are provided with only tooth rows that partially deform the stack of recording materials to bind the stack of recording materials. [Means for solving the problem]

[0005] The invention of claim 1 is a binding device comprising upper teeth having a tooth row for forming unevenness in a stack of recording materials, lower teeth having a tooth row for forming unevenness in the stack of recording materials and pairing with the upper teeth, and a holding portion that holds the stack of recording materials at a location other than the location where the upper teeth and lower teeth have the binding function during the binding process using the upper teeth and the lower teeth, wherein the holding portion has an upper tooth protruding portion arranged in line with the tooth row of the upper teeth and having a first surface parallel to the base at a position lower than the top of the tooth row and higher than the base of the tooth row, and a lower tooth protruding portion arranged in line with the tooth row of the lower teeth and having a second surface parallel to the base at a position lower than the top of the tooth row and higher than the base of the tooth row, and wherein the stack of recording materials is clamped and held by the first surface and the second surface during the binding process using the upper teeth and the lower teeth. An invention according to claim 2 is the binding device according to claim 1, characterized in that the holding portions are provided on both ends of the tooth row of the upper teeth and the tooth row of the lower teeth. The invention of claim 3 is the binding device described in claim 1, further comprising a loading means for applying a predetermined load to the stack of recording materials sandwiched between the upper teeth and the lower teeth during the binding process, and characterized in that the maximum stress applied to the stack of recording materials by the holding portion when the load is applied by the loading means is smaller than the maximum stress applied to the stack of recording materials by the tooth row of the upper teeth and the tooth row of the lower teeth when the load is applied. The invention of claim 4 is the binding device described in claim 3, characterized in that the maximum stress that the holding portion applies to the stack of recording materials when the load is applied by the loading means is less than half the maximum stress that the tooth row of the upper teeth and the tooth row of the lower teeth apply to the stack of recording materials when the load is applied. The invention of claim 5 is a binding device comprising upper teeth having a tooth row for forming unevenness in a stack of recording materials, and an upper tooth protrusion arranged in parallel to the tooth row and having a first surface parallel to the base at a position lower than the top of the tooth row and higher than the base of the tooth row, a tooth row for forming unevenness in the stack of recording materials, and a lower tooth protrusion arranged in parallel to the tooth row and having a second surface parallel to the base at a position lower than the top of the tooth row and higher than the base of the tooth row, lower teeth paired with the upper teeth, and a load means for applying a predetermined load to the stack of recording materials sandwiched between the upper teeth and the lower teeth, wherein the gap between the first surface of the upper tooth protrusion and the second surface of the lower tooth protrusion when the stack of recording materials is sandwiched between the upper teeth and the lower teeth and the load is applied by the load means is smaller than the thickness of the stack of recording materials when the load is not applied. The invention of claim 6 is the binding device described in claim 5, characterized in that when the stack of recording materials is clamped between the upper teeth and the lower teeth and the load is applied by the loading means, the gap between the first surface of the upper tooth protrusion and the second surface of the lower tooth protrusion is larger than the narrowest gap between the tooth row of the upper teeth and the tooth row of the lower teeth when the load is applied. The invention of claim 7 is the binding device described in claim 6, characterized in that the gap between the first surface of the upper tooth protrusion and the second surface of the lower tooth protrusion when the stack of recording materials is clamped between the upper teeth and the lower teeth and the load is applied by the loading means is 1.7 to 2.5 times larger than the narrowest gap between the tooth row of the upper teeth and the tooth row of the lower teeth when the load is applied. The invention of claim 8 is the binding device described in claim 5, characterized in that a stress determined by the width in the direction in which the tooth rows of the upper teeth and the tooth rows of the lower teeth are aligned at the opposing portions of the first surface of the upper tooth protrusion and the second surface of the lower tooth protrusion is smaller than the maximum stress that the tooth rows of the upper teeth and the tooth rows of the lower teeth apply to the stack of recording materials when the stack of recording materials is clamped between the upper teeth and the lower teeth and the load is applied by the loading means. The invention of claim 9 is the binding device described in claim 8, characterized in that the width of the opposing parts in the said direction is 4 to 12% of the smaller of the sum of the widths of the upper tooth protrusion and the tooth row of the upper teeth in the said direction and the sum of the widths of the lower tooth protrusion and the tooth row of the lower teeth in the said direction. The invention according to claim 10 provides an upper tooth having a tooth row for forming unevenness on a recording material stack, and an upper tooth protruding portion arranged in parallel with the tooth row and having a first surface parallel to the base at a position lower than the top of the tooth row and higher than the base of the tooth row, and a tooth row for forming unevenness on the recording material stack, and a lower tooth protruding portion arranged in parallel with the tooth row and having a second surface parallel to the base at a position lower than the top of the tooth row and higher than the base of the tooth row, and a lower tooth forming a pair with the upper tooth. During the binding process by the upper teeth and the lower teeth, the recording material stack is sandwiched and held by the first surface and the second surface. The binding member is characterized by: The invention according to claim 11 has an image forming section which forms an image, a transport section which transports recording materials on which an image has been formed by the image forming section, upper teeth which contact the recording material stack from one direction of a recording material stack formed by stacking the recording materials transported by the transport section and bind the recording material stack without a staple, and lower teeth which face the upper teeth and contact the recording material stack from the other direction and bind the recording material stack without a staple, wherein the upper teeth and the lower teeth are different from a tooth row for forming unevenness in the recording material stack and a portion having a binding function of the upper teeth and the lower teeth when the upper teeth and the lower teeth bind the recording material stack. and a holding portion that holds the stack of recording materials at a location where the stack of recording materials is spaced apart from the top of the teeth, the holding portion having an upper teeth protruding portion that is arranged in line with the tooth row of the upper teeth and has a first surface parallel to the base at a position lower than the top of the tooth row and higher than the base of the tooth row, and a lower teeth protruding portion that is arranged in line with the tooth row of the lower teeth and has a second surface parallel to the base at a position lower than the top of the tooth row and higher than the base of the tooth row, and the image forming system is characterized in that during a binding process using the upper teeth and lower teeth, the stack of recording materials is clamped and held by the first surface and the second surface. The invention of claim 12 is a binding device comprising upper teeth having a tooth row for forming unevenness in a stack of recording materials, lower teeth having a tooth row for forming unevenness in the stack of recording materials and pairing with the upper teeth, and a holding portion that holds the stack of recording materials at a location other than a location where the upper teeth and lower teeth have a binding function during binding processing by the upper teeth and the lower teeth, the holding portion being disposed between the tooth row of the upper teeth and the tooth row of the lower teeth. The invention of claim 13 is the binding device described in claim 12, characterized in that the retaining portion is provided in a central portion including the center of the length in the direction in which each of the tooth rows of the upper teeth and the tooth row of the lower teeth are aligned. Claim 14 The invention relates to a binding member comprising upper teeth having a tooth row for forming unevenness in a stack of recording materials, and an upper tooth protruding portion arranged in parallel with the tooth row and lower than the top of the tooth row and higher than the base of the tooth row, a tooth row for forming unevenness in the stack of recording materials, and a lower tooth protruding portion arranged in parallel with the tooth row and lower than the top of the tooth row and higher than the base of the tooth row, and which forms a pair with the upper tooth, wherein the lower tooth has a shape rotated 180 degrees from the upper tooth around an axis that intersects the direction in which the tooth row of the upper teeth is arranged and the direction in which the upper tooth protruding portion protrudes. Claim 15 The invention according to claim 1 is characterized in that the upper teeth and the lower teeth are molded using the same mold. 14 The binding member according to claim 1, Effect of the Invention

[0006] According to the invention of claim 1, misalignment and inclination of the teeth are suppressed compared to a case in which only the tooth rows for binding a stack of recording materials are provided on the upper and lower teeth. According to the invention of claim 2, the recording material stack is stably held. According to the invention of claim 3, a decrease in the binding function for the recording material stack caused by an excessively large holding force in the holding portion is suppressed. According to the invention of claim 4, deformation and breakage of the recording material due to the holding portion is suppressed. According to the invention of claim 5, misalignment and inclination of the teeth are suppressed, compared to a case in which only the tooth rows for binding a stack of recording materials are provided on the upper and lower teeth. According to the invention of claim 6, it is possible to prevent the gap between the upper and lower teeth protruding portions from being too small, thereby preventing a significant decrease in the binding function for the stack of recording materials. According to the seventh aspect of the invention, a significant decrease in the binding function for the stack of recording materials is suppressed, compared to when the gap between the upper teeth protruding portion and the lower teeth protruding portion is too small or too large. According to the invention of claim 8, the decrease in binding force is reduced compared to the case where the maximum stress in the protruding portion is greater than the maximum stress in the dentition. According to the invention of claim 9, deviation or inclination of the teeth is suppressed compared to when the width of the protruding portion is too small or too large. According to the invention of claim 10, deviation and inclination of the teeth are suppressed compared to a case where only the tooth rows for binding a recording material stack are provided on the upper and lower teeth. According to the invention of claim 11, misalignment and inclination of the teeth are suppressed compared to a case in which only the tooth rows for binding a stack of recording materials are provided on the upper and lower teeth. According to the invention of claim 12, compared to a case in which only the upper and lower teeth are provided with tooth rows for binding stacks of recording material, it is possible to suppress misalignment and inclination of the teeth, and to increase the degree of freedom when designing the position of the holding part relative to the tooth rows. According to the invention of claim 13, compared to the case where the retaining portion is provided other than in the central part of the dentition, a significant loss of symmetry between the upper and lower teeth is suppressed, and the variation in binding force across the entire dentition is reduced. Claim 14 According to the invention, compared to a case in which the upper and lower teeth are provided with only tooth rows for binding a stack of recording materials, misalignment and inclination of the teeth are suppressed and the upper and lower teeth are made common. Claim 15 According to the invention, the manufacturing cost can be reduced as compared with the case where molding is performed using separate molds. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram showing a configuration of a recording material processing system to which an embodiment of the present invention is applied; [Diagram 2] FIG. 2 is a diagram showing a configuration of a post-processing device. [Diagram 3] 3 is a diagram of the binding unit and the like as viewed from the direction of arrow III in FIG. 2. [Figure 4] 4(a) and (b) are views of the advance / retract mechanism as viewed from the direction of arrow IV in FIG. [Diagram 5] 4(a) and (b) are views of the binding member as viewed from the direction of arrow V in FIG. [Figure 6] This is an enlarged view of the 5X portion in Figure 5(b) when a stack of paper is clamped between the upper and lower teeth, where (a) shows the state in which the upper teeth are slightly advanced, and (b) shows the state in which the upper teeth are advanced further. [Figure 7] 11 is a graph showing the relationship between the gap of the holding portion and the binding force. [Figure 8] 11 is a graph showing the relationship between the surface roughness of the top of the protrusion and the binding force. [Figure 9] 1 is a graph showing the relationship between the ratio of the width of a protrusion, the load received by the protrusion, and the load received by the tooth row. [Figure 10] FIG. 13 is a diagram of a binding member having retaining portions at two locations between rows of teeth. [Figure 11] FIG. 13 is a diagram of a binding member having a retaining portion in the center of the tooth row. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] <First embodiment> Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a configuration of an image forming system 500 to which the present embodiment is applied. 1 includes an image forming apparatus 1 such as a printer or a copier that forms an image on paper P as an example of a recording material, and a post-processing apparatus 2 that performs a binding process or the like on a plurality of sheets of paper P (a stack of paper) on which images have been formed by the image forming apparatus 1. The paper P is an example of a stack of recording materials in this embodiment.

[0009] The image forming apparatus 1 is provided with four image forming units 100Y, 100M, 100C, and 100K as examples of image forming sections, and these four image forming units are also collectively referred to as image forming units 100. Each image forming unit 100 forms an image based on each color image data. The image forming apparatus 1 is also provided with a laser exposure device 101 that exposes a photoconductor drum 107 provided in each image forming unit 100. The image forming apparatus 1 is also provided with an intermediate transfer belt 102 onto which the toner images of each color formed in each image forming unit 100 are multiple-transferred.

[0010] Furthermore, the image forming apparatus 1 is provided with a primary transfer roll 103 which sequentially transfers the respective color toner images formed in the respective image forming units 100 onto an intermediate transfer belt 102, a secondary transfer roll 104 which collectively transfers the respective color toner images transferred onto the intermediate transfer belt 102 onto a sheet of paper P, and a fixing device 105 which fixes the respective color toner images which have been secondarily transferred onto the sheet of paper P. The image forming apparatus 1 is also provided with a main body control unit 106 which is constituted by a program-controlled CPU (Central Processing Unit) and which controls the operation of the image forming apparatus 1.

[0011] In each image forming unit 100 of the image forming apparatus 1, a toner image of each color is formed through a process of charging the photosensitive drum 107, a process of forming an electrostatic latent image on the photosensitive drum 107 by scanning exposure from a laser exposure device 101, and a process of developing the formed electrostatic latent image with toner of each color. The color toner images formed in the image forming units 100 are electrostatically transferred onto the intermediate transfer belt 102 by the primary transfer roll 103. Then, the color toner images are transported to a position where the secondary transfer roll 104 is installed as the intermediate transfer belt 102 moves.

[0012] Meanwhile, in the image forming apparatus 1, a plurality of sheets P of different sizes and types are stored in the sheet storage units 110A to 110D, respectively. When an image is formed on the paper P, for example, the paper P is taken out from the paper storage unit 110A by the pickup roll 111 and is transported to the position of the registration roll 113 by the transport roll 112, one sheet at a time.

[0013] Further, a sheet of paper P is supplied from a registration roll 113 in accordance with the timing at which the toner images of each color on the intermediate transfer belt 102 are conveyed to the position where the secondary transfer roll 104 is installed. As a result, the toner images of each color are electrostatically transferred onto the paper P at once by the action of the transfer electric field formed by the secondary transfer roll 104 .

[0014] Thereafter, the paper P onto which the color toner images have been secondarily transferred is peeled off from the intermediate transfer belt 102 and conveyed to a fixing device 105. In the fixing device 105, the color toner images are fixed onto the paper P by a fixing process using heat and pressure. Then, the paper P that has passed through the fixing device 105 is discharged from a paper discharge section T of the image forming apparatus 1 by a transport roll 114 and is supplied to the post-processing device 2 . The post-processing device 2, which is an example of a binding device, is disposed downstream of the paper discharge section T of the image forming device 1, and performs post-processing such as punching and stapling on the paper P on which an image has been formed.

[0015] FIG. 2 is a diagram showing the configuration of the post-processing device 2. As shown in FIG. The post-processing device 2 is provided with a transport unit 21 connected to a paper discharge section T of the image forming device 1, and a finisher unit 22 that performs a predetermined process on the paper P transported by the transport unit 21. The post-processing device 2 is also provided with a paper processing control unit 23 that is configured with a program-controlled CPU and controls each mechanical unit of the post-processing device 2. The paper processing control unit 23 is connected to the main body control unit 106 via a signal line (not shown), and transmits and receives control signals and the like to and from the main body control unit 106.

[0016] The transport unit 21 of the post-processing device 2 is provided with a punch function section 30 that performs hole punching, and a plurality of transport rolls 211 that function as a transport section. The plurality of transport rolls 211 transport the paper P after the image formation by the image forming device 1 toward the finisher unit 22.

[0017] The finisher unit 22 includes a finisher unit main body 221, a paper stacking section 60 that stacks the required number of sheets of paper P to generate a paper stack B, and a binding unit 51 that performs binding on the ends of the paper stack B generated in the paper stacking section 60. The finisher unit 22 is also provided with a transport roll 61 that is rotatably provided and used to transport the paper stack B generated in the paper stacking section 60. Furthermore, a movable roll 62 is provided that is swingable about a rotation shaft 62a as a movement center and can move to a position relative to the transport roll 61 and to a position where it is in pressure contact with the transport roll 61. Further, there is provided a stacker 80 on which the sheet stack B transported by the transport roll 61 and the movable roll 62 is stacked. The stacker 80 moves up and down depending on the amount of the sheet stack B it holds.

[0018] When processing is performed by the post-processing device 2, first, the paper P is carried from the image forming device 1 into the transport unit 21 of the post-processing device 2. In the transport unit 21, after the punching function section 30 punches holes, the paper P is sent to the finisher unit 22 by the transport rolls 211. If there is no instruction to punch holes, the paper P is sent to the finisher unit 22 as is without being subjected to the punching process by the punching function section 30.

[0019] The paper sheet P sent to the finisher unit 22 is transported to the paper stacking section 60. In detail, the paper sheet P is transported to above the paper stacking section 60 and then falls into the paper stacking section 60. The paper sheet P is supported from below by a support plate 67 provided in the paper stacking section 60. Furthermore, the paper sheet P slides on the support plate 67 due to a paddle 69 provided on the support plate 67 that tilts and rotates.

[0020] Thereafter, the paper sheet P hits the end guide 64 attached to the end of the support plate 67. As a result, in this embodiment, the movement of the paper sheet P is stopped. Thereafter, this operation is performed every time a sheet P is conveyed from the upstream side, and a sheet stack B is generated on the sheet stacking section 60 with the rear ends of the sheets P aligned.

[0021] In this embodiment, an alignment member 65 is provided that is movable in the width direction of the paper stack B, i.e., in the direction perpendicular to the paper surface of Fig. 2, and aligns the position of the paper stack B in the width direction. Two alignment members 65 are provided, one alignment member 65 is disposed on one side of the paper stack B in the width direction, and the other alignment member 65 is disposed on the other side of the paper stack B in the width direction. In this embodiment, every time a sheet P is supplied to the support plate 67, the edge portion in the width direction of the sheet P is pressed by the alignment member 65, and the positions of the multiple sheets P in the width direction are aligned.

[0022] Then, when a predetermined number of sheets P are stacked on the support plate 67 and a sheet bundle B is generated on the support plate 67, the binding unit 51 executes a binding process on the end of the sheet bundle B. The binding unit 51 is provided with a binding member that presses the paper-sheet stack B. This binding member is composed of upper teeth arranged on the upper side of the paper-sheet stack B to be generated, and lower teeth arranged on the lower side of the paper-sheet stack B to be generated. The binding member, the upper teeth, and the lower teeth will be described in detail later. Furthermore, in this embodiment, an advancing / retracting mechanism 51A is provided which moves one of the upper teeth and the lower teeth forward and backward relative to the other.

[0023] In this embodiment, when a stack of paper-sheets B is generated on the support plate 67, the stack of paper-sheets B is positioned between the upper and lower teeth. The upper and lower teeth are then pressed against the stack of paper-sheets B from both sides of the stack of paper-sheets B, partially deforming the stack of paper-sheets, pressing the sheets that make up the stack of paper-sheets B together, and binding the stack of paper-sheets B. In this way, in this embodiment, the binding process is performed on the stack of paper-sheets B without using needles such as staples.

[0024] When the binding process for the paper stack B is completed, the movable roll 62 advances toward the transport roll 61, and the paper stack B is sandwiched between the movable roll 62 and the transport roll 61. Thereafter, the transport roll 61 and the movable roll 62 are rotated, and the bound paper stack B is transported to the stacker 80.

[0025] FIG. 3 is a diagram of the binding unit 51 and the like as viewed from the direction of arrow III in FIG. 3, in this embodiment, the binding unit 51 is disposed in a state inclined with respect to the transport direction of the paper stack B. Furthermore, the binding unit 51 is provided with a binding member 81, and in this embodiment, the binding member 81 sandwiches the paper stack B to perform a binding process for the paper stack B.

[0026] In the present embodiment, the binding unit 51 is disposed to face the corners of the sheet bundle B and performs binding processing on the corners of the sheet bundle B. Note that the above-described binding at the corner is one example of the binding process, and the binding unit 51 may be disposed to face the side of the paper stack B and the binding process may be performed at the side. Also, the binding unit 51 may be provided movably and the binding process may be performed at multiple points of the paper stack B.

[0027] 4(a) and (b) are views of the advancing and retreating mechanism 51A as viewed from the direction of arrow IV in FIG. As shown in FIG. 4(a), in this embodiment, a binding member 81 that is driven by a forward / backward mechanism 51A to press against a stack of paper-sheets B is provided. The binding member 81 is configured with upper teeth 83A and lower teeth 83B disposed at a position opposing the upper teeth 83A. Note that Fig. 4(a) shows a state in which the upper teeth 83A are retracted from the lower teeth 83B.

[0028] 4(a), the advance / retract mechanism 51A is provided with a rotary gear 511, a gear motor GM, and a transmission gear 512 that transmits the driving force from the gear motor GM to the rotary gear 511. A crank member 513 is provided so as to be able to swing, and a protrusion 511A provided on the side surface of the rotary gear 511 is located within an elongated hole 513A formed in the crank member 513. Further, the advancing / retreating mechanism 51A is provided with a spring 514 that urges the crank member 513 downward, and an advancing / retreating member 515 is attached to the left end of the crank member 513 in the figure. In this embodiment, the upper teeth 83A are attached to the lower end of this advancing / retreating member 515.

[0029] When the binding process is performed, the gear motor GM is driven, the rotating gear 511 rotates in the direction of the arrow 4A, and the protrusion 511A moves upward. Then, the right end of the crank member 513 in the figure is lifted upward, and the left end of the crank member 513 in the figure is pulled downward by the spring 514, and the advancing and retracting member 515 moves downward. As a result, the upper teeth 83A advance toward the lower teeth 83B, resulting in the state shown in FIG. 4(b).

[0030] Then, the upper teeth 83A and the lower teeth 83B are pressed against the stack of sheets P of the paper stack B (not shown) from both sides in the stacking direction of the sheets P of the paper stack B, causing the paper stack B to partially deform and causing the sheets P of the paper stack B to be pressed together. Thereafter, the upper teeth 83A separate from the paper stack B, and the paper stack B which has been bound can be removed from between the upper teeth 83A and the lower teeth 83B. In this manner, in the present embodiment, the upper teeth 83A are moved in the up-down direction, which is a predetermined forward and backward direction, to perform the binding process on the paper stack B.

[0031] In this embodiment, as described above, the upper teeth 83A are moved using the rotating gear 511 and the crank member 513, and the upper teeth 83A and the lower teeth 83B are pressed against the stack of paper B, thereby applying a predetermined load to the stack of paper B and performing the binding process for the stack of paper B. This mechanism is one example of a load means, and a non-circular cam may be pressed against upper teeth 83A or a portion that moves in conjunction with upper teeth 83A to move upper teeth 83A and apply a load to sheet stack B. Also, a load may be applied to sheet stack B by another mechanism.

[0032] 5(a) and (b) are diagrams of the binding member 81 viewed from the direction of the arrow V in FIG. 3, and show the cross-sectional shape of the binding member 81. FIG. As shown in Fig. 5(a), the binding member 81 is composed of two opposing tooth shapes, upper teeth 83A and lower teeth 83B. In this embodiment, the upper teeth 83A are rotated 180 degrees to become the lower teeth 83B, which have the same tooth shape. As a result, the upper teeth 83A and the lower teeth 83B are manufactured by molding using the same mold.

[0033] The upper teeth 83A and the lower teeth 83B are provided with bases 41 extending in the left-right direction in the figure. Furthermore, on the opposing surfaces of the bases 41 of the upper teeth 83A and the lower teeth 83B, tooth rows 90 for forming irregularities on the stack of paper-sheets B are provided. The tooth rows 90 of the upper teeth 83A and the lower teeth 83B are composed of a plurality of convex portions 91 arranged in a row along the longitudinal direction of the base 41, and a plurality of concave portions 92 arranged in a row along the longitudinal direction of the base 41.

[0034] The convex portions 91 of the upper teeth 83A protrude from the surface of the base 41 toward the lower teeth 83B. Meanwhile, the convex portions 91 of the lower teeth 83B protrude from the surface of the base 41 toward the upper teeth 83A. Also, the concave portions 92 are disposed between two adjacent convex portions 91. As a result, the convex portions 91 and the concave portions 92 are disposed alternately in the longitudinal direction of the base 41. It should be noted that the convex portion 91 and the concave portion 92 have a predetermined width, and this width extends along a direction intersecting the direction in which the tooth row 90 is arranged and the direction in which the convex portion 91 protrudes.

[0035] Here, an inclined portion 912 is provided on each of the convex portions 91 of the upper teeth 83A and the lower teeth 83B. The inclined portions 912 are both side surfaces in a mountain-shaped cross section of each of the protrusions 91 provided on the upper teeth 83A and the lower teeth 83B. More specifically, the inclined portions 912 are formed on the outer surface of the protrusions 91 in a portion that slopes obliquely downward from the top of the protrusions 91 to the valley of the recesses 92.

[0036] In the upper teeth 83A and the lower teeth 83B, one protruding portion 93 and the other protruding portion 94 are provided side by side on both ends of the tooth row 90. The one protruding portion 93 and the other protruding portion 94 protrude in the direction in which the convex portion 91 protrudes, and have, at their tips in the protruding direction, one apex 931 and the other apex 941, respectively. In this embodiment, the apex 931 and the apex 941 have at least a portion of a surface that is parallel to the base portion 41. The parallel surface may be flat. 5(a), one apex 931 of upper tooth 83A and the other apex 941 of lower tooth 83B are disposed to face each other and are configured to be substantially parallel to each other. Similarly, the other apex 941 of upper tooth 83A and one apex 931 of lower tooth 83B are disposed to face each other and are configured to be substantially parallel to each other.

[0037] In this embodiment, the height of one protruding portion 93 and the other protruding portion 94 in the direction in which they protrude from the base portion 41 is configured to be lower than the height of the convex portion 91. More specifically, the protruding portions 93 and 94 are configured to be higher than the base portion 41 and lower than the top of the convex portion 91. In the present embodiment, the height of one protruding portion 93 in the direction protruding from the base 41 is configured to be greater than the height of the other protruding portion 94 in the direction protruding from the base 41. However, as another embodiment, the height of one protruding portion 93 in the direction protruding from the base 41 and the height of the other protruding portion 94 in the direction protruding from the base 41 may be made equal.

[0038] Moreover, the one protruding portion 93 and the other protruding portion 94 have inclined portions 932 and 942, respectively. The inclined portion 932 is formed on the surface of one protruding portion 93 on the side on which the tooth row 90 is arranged. More specifically, the inclined portion 932 is formed on a portion of the outer surface of the cross section of one protruding portion 93 that slopes obliquely downward from the peak 931 toward the valley of the adjacent recess 92. Similarly, the inclined portion 942 is provided on the surface of the other protruding portion 94 on the side on which the tooth row 90 is arranged.

[0039] FIG. 5(b) is a diagram showing a state in which the upper teeth 83A and the lower teeth 83B are butted against each other without the stack of paper-sheets B being sandwiched. In this state, in this embodiment, the teeth rows 90 of the upper teeth 83A and the teeth rows 90 of the lower teeth 83B mesh with each other, and a region of contact is generated between the inclined portions 912 of the upper teeth 83A and the inclined portions 912 of the lower teeth 83B. Also, a region of contact is generated between the inclined portion 932 of one protruding portion 93 of the upper tooth 83A and the inclined portion 912 of the lower tooth 83B. Similarly, a region of contact is generated between the inclined portion 932 of one of the lower teeth 83B and the inclined portion 912 of the upper tooth 83A.

[0040] As described above, when the inclined portions come into contact with each other, the stress in the stacking direction of the sheets P applied from each inclined portion to the sheet stack B during the binding process becomes larger than when the inclined portions do not come into contact with each other. Therefore, in this embodiment, the binding function is improved compared to a case where the inclined portions are not in contact with each other.

[0041] 5(b), when the upper teeth 83A and the lower teeth 83B are butted against each other, the apex 931 of one protruding portion 93 and the apex 941 of the other protruding portion 94 do not come into contact with each other, and a gap G1 is generated. In this embodiment, the stack of paper-sheets B is held in this gap G1, and one holding portion at both ends of the tooth row 90 is a first holding portion 841, and the other holding portion is a second holding portion 842. More specifically, the first holding portion 841 is formed by one apex 931 of the upper teeth 83A and the other apex 941 of the lower teeth 83B. Similarly, the second holding portion 842 is formed by the other apex 941 of the upper teeth 83A and one apex 931 of the lower teeth 83B. The holding function of the holding portions 841 and 842 will be described in detail later.

[0042] 6(a) and (b) are diagrams showing the state when binding processing is performed on paper stack B. Here, the portion indicated by 5X in FIG. 5(b) is enlarged. FIG. 6(a) is a diagram showing the state when pressing for binding processing starts, and FIG. 6(b) is a diagram showing the state when pressing for binding processing ends. This paper stack B is a large number of papers, about 10 sheets, suitable for copying and printing.

[0043] First, when performing binding processing on the paper stack B, with the paper stack B positioned between the upper teeth 83A and the lower teeth 83B, the upper teeth 83A is advanced toward the lower teeth 83B using the advancing / retracting mechanism shown in FIG. When the upper teeth 83A are advanced, the upper teeth 83A are pressed against one surface of the stack of paper-sheets B, and the lower teeth 83B are pressed against the other surface of the stack of paper-sheets B, as shown in FIG. 6(a).

[0044] When the upper teeth 83A advance further by a predetermined amount, the upper teeth 83A and the lower teeth 83B approach each other even more, and the stack of paper-sheets B is pressed most strongly by the upper teeth 83A and the lower teeth 83B, as shown in Fig. 6(b). This is the state in which the predetermined load is being applied. At this time, the convex portions 91 of the upper teeth 83A enter between the convex portions 91 of the lower teeth 83B. Thereafter, the upper teeth 83A retract from the sheet stack B, making it possible to remove the bound sheet stack B, and the binding process for the sheet stack B is completed.

[0045] When the binding process for the paper stack B is completed, the portion of the paper stack B that is sandwiched by the binding member 81 is deformed into an uneven shape following the shape of the portion having the binding function of the upper teeth 83A and the lower teeth 83B, and a bound portion is formed. In this bound portion, the sheets P that make up the paper stack B are in a state of being pressed against each other.

[0046] During this binding process, when the stack of paper sheets B is sandwiched and pressed between the upper teeth 83A and the lower teeth 83B, the stack of paper sheets B is compressed in the stacking direction of the paper sheets P. At this time, the stack of paper sheets B is deformed into an uneven shape following the uneven shape formed by the tooth row 90 of the upper teeth 83A and the lower teeth 83B, and is compressed and compacted. At this time, the paper sheets P may break in the deformed portion.

[0047] 6(b), in this embodiment, when stack of paper-sheets B is pressed most strongly, there is a minimum gap G2 between inclined portion 912 of upper teeth 83A and inclined portion 912 of lower teeth 83B. In this state, in this embodiment, the maximum stress applied to stack of paper-sheets B by tooth row 90 of upper teeth 83A and lower teeth 83B occurs at the portion of gap G2. In the portion of the minimum gap G2, the stack of sheets B is compressed most strongly in the stacking direction of the sheets P. For example, in this embodiment, the stack of sheets B is compressed to 20% of its original thickness T in the gap G2.

[0048] Furthermore, when performing the binding process on the paper stack B, if the upper teeth 83A are advanced, the protruding portions 93 and 94 of the upper teeth 83A approach the paper stack B. If the upper teeth 83A are further advanced, the holding portions 841 and 842 come into contact with the surface of the paper stack B. Thereafter, when the upper teeth 83A advance further, the holding portions 841 and 842 are pressed against the stack of paper-sheets B. As a result, the stack of paper-sheets B begins to be compressed in the stacking direction of the paper-sheets P by the holding portions 841 and 842.

[0049] Then, when the upper teeth 83A advance by a predetermined amount, as shown in Fig. 6(b), the top 931 of the protrusion 93 and the top 941 of the protrusion 94 approach each other to the extent that the gap becomes G3 in the retaining portion 842. Similarly, in the retaining portion 841 shown in Fig. 5(b), the top 931 of the protrusion 93 and the top 941 of the protrusion 94 approach each other to the extent that the gap becomes G3. In this state, the maximum stress that the holding portions 841 and 842 apply to the stack of paper-sheets B occurs in the gap G3.

[0050] In this binding process, when the holding portions 841 and 842 come into contact with and start to be pressed against the paper stack B, the paper stack B is held by the holding portions 841 and 842. In the holding portions 841 and 842, deformation and breakage of the sheets P constituting the paper stack B is suppressed. As described above, the holding units 841 and 842 in this embodiment hold the paper-sheet stack B at a location different from the location having the binding function.

[0051] Incidentally, when the paper P breaks at the portion where the paper stack B is deformed during the binding process, a force is generated that causes the teeth to shift or tilt. At this time, if the holding portions 841 and 842 do not exist, the teeth may shift or tilt toward the broken portion due to the break, and the binding force may be significantly reduced. In the present embodiment, since the sheet stack B is held by the holding portions 841 and 842, the upper teeth 83A and the lower teeth 83B are prevented from shifting or tilting.

[0052] Here, gap G3 between protruding portions 93 and 94 constituting holding portions 841 and 842 will be described in detail. In the binding member 81, the gap G3 is smaller than the original thickness T of the paper stack B, and the paper stack B is compressed to a thickness smaller than the original thickness T. In the portion of this gap G3, the paper stack B is compressed to a thickness of, for example, 50% of the original thickness T, and the paper stack B is held. Furthermore, the gap G3 is larger than the gap G2 in the binding member 81. If the gap G3 is too small compared to the gap G2, the maximum stress that the tooth row 90 applies to the paper stack B is reduced, and the binding function is significantly reduced.

[0053] 7 is a diagram showing the relationship between the gap between the holding portions 841, 842 when the upper teeth 83A and the lower teeth 83B are butted together, and the binding force. The horizontal axis of the diagram shows the gap G1 between one protruding portion 93 and the other protruding portion 94 when they are butted together without sandwiching the paper stack B, and the vertical axis shows the binding force. Here, the results are shown when the pitch is 1.6 mm or 1.73 mm. This pitch is the distance between the adjacent protruding portions 91 of the upper teeth 83A and the lower teeth 83B. The dashed line shows the target value of the binding force.

[0054] When the gap G1 between the holding portions 841, 842 is set to 150 to 300 μm, as shown in FIG. 7, in both cases where the pitch is 1.6 mm and 1.73 mm, the binding force becomes significantly high and exceeds the target value. Here, when stack of paper-sheets B is sandwiched, the gap between the holding portions 841, 842 becomes gap G3, and if gap G1 is 150 to 300 μm, and the narrowest gap G2 when stack of paper-sheets B is sandwiched and a load is applied is 200 μm, then gap G3 becomes 350 μm to 500 μm. In other words, when attempting to obtain a binding force exceeding the target value, gap G3 becomes 1.7 to 2.5 times larger than gap G2. By making gap G3 1.7 to 2.5 times larger than gap G2, a good binding function can be obtained.

[0055] Incidentally, when a force that causes misalignment or tilting of the teeth occurs during binding processing, a frictional force is generated between the holding portions 841, 842 and the surface of the paper stack B. Since the force that causes the misalignment or tilt and the frictional force are opposite forces, the greater the frictional force, the more the teeth are prevented from misaligning or tilting. In this embodiment, the frictional force is increased by adjusting the surface roughness Ra of the holding portions 841 and 842. This surface roughness Ra is the arithmetic mean roughness defined in JIS B 0601.

[0056] 8 is a diagram showing the relationship between the surface roughness of the holding parts 841, 842 and the binding force. The horizontal axis of the diagram shows the surface roughness Ra of each of the top parts 931, 941 that constitute the holding parts 841, 842, and the vertical axis shows the binding force. Here, the average value and the minimum value when measurements are taken multiple times are shown. The dashed line shows the target value of the binding force.

[0057] If the surface roughness of the tops 931 and 941 is set to Ra 1 to 10 μm, as shown in FIG. 8, both the average value and the minimum value of the binding force exceed the target value. Here, since the binding force decreases as the surface roughness decreases, if the surface roughness falls below Ra1 μm, there is a concern that the binding force will fall below the target value. On the other hand, if the surface roughness exceeds Ra10 μm and becomes too large, there is a concern that the surface roughness will damage the surface of the paper P, causing a decrease in binding force. Therefore, by setting the surface roughness of the tops 931, 941 to Ra1 to 10 μm, a good binding function can be stably obtained.

[0058] Incidentally, the stress that the holding portions 841 and 842 apply to the paper stack B during the binding process is determined by the width W1 (see FIG. 5B) of the portion where the top portion 931 and the top portion 941 face each other. If the width W1 becomes larger, when a load is applied from the forward / reverse mechanism 51A, the load received by the holding portions 841, 842 becomes larger, but on the other hand, the load received by the tooth row 90 becomes smaller, so that the stress applied by the tooth row 90 to the paper stack B becomes smaller and the binding function is reduced. Therefore, in order to obtain a good binding function with a limited load, it is preferable that the width W1 is not too large. For example, if the maximum stress applied to the paper stack B by the holding portions 841 and 842 is made smaller than the maximum stress applied by the tooth row 90, a better binding function can be obtained compared to the case where this configuration is not used.

[0059] 9 is a diagram showing the relationship between the ratio of width W in a tooth, the load received by the retaining portions 841 and 842, and the load received by the tooth row 90. This width W is the sum of the width W1 where the apex 931 and the apex 941 face each other in the retaining portion 841 and the width W1 where they face each other in the retaining portion 842. The horizontal axis of the figure shows the ratio W / W2 of width W to tooth width W2 (see FIG. 5(b)) expressed as a percentage. This tooth width W2 is the sum of the width of protrusions 93 and 94 and the width of tooth row 90. The vertical axis on the left side of the figure shows the load received by retaining portions 841, 842 when a load is applied, and the second vertical axis on the right side of the figure shows the load received by tooth row 90. Furthermore, the solid line shows the load on retaining portions 841, 842 as the ratio W / W2 changes, and the dashed line shows the load on tooth row 90 as the ratio W / W2 changes.

[0060] As shown in Fig. 9, as the ratio W / W2 increases, the load received by the holding portions 841 and 842 increases, but on the other hand, the load received by the tooth row 90 decreases. Due to this relationship, in the present embodiment, the binding member 81 is configured so that the ratio W / W2 is 4 to 12%. If the ratio W / W2 falls below 4% and the load received by the holding portions 841 and 842 becomes too small, the maximum stress applied by the holding portions 841 and 842 to the paper stack B becomes small, and the holding function is significantly reduced. On the other hand, if the ratio W / W2 exceeds 12% and the load received by the tooth row 90 becomes too small, the maximum stress applied by the tooth row 90 to the paper stack B becomes small, and the binding function is significantly reduced.

[0061] In the present embodiment described above, the upper teeth 83A and the lower teeth 83B have the same shape, so the tooth width W2 was calculated without distinction. In other embodiments, when the tooth widths of the upper teeth 83A and the lower teeth 83B are different, the smaller one is set as W2, and the ratio W / W2 is set to 4 to 12%.

[0062] In the present embodiment described above, the maximum stress that the holding portions 841 and 842 apply to the paper stack B is smaller than the maximum stress that the tooth row 90 applies to the paper stack B. This prevents the binding function from being significantly reduced. Furthermore, in the present embodiment described above, the maximum stress that the holding portions 841 and 842 apply to the paper stack B is equal to or less than half the maximum stress that the tooth row 90 applies to the paper stack B. This configuration prevents the paper stack B from being compressed too much in the holding portions 841 and 842, and prevents deformation or breakage in the holding portions 841 and 842.

[0063] In the above-described embodiment, the gap G3 between the holding portions 841, 842 and the facing width W1 are adjusted to prevent the maximum stress applied by the holding portions 841, 842 to the paper stack B from becoming too large. However, the configuration for preventing the maximum stress in the holding portions 841, 842 from becoming too large is not limited to this. For example, in the present embodiment, the extension width of protrusions 93 and 94 in the extension direction of convex portion 91 and concave portion 92 may be configured to be more than twice the extension width of convex portion 91 and concave portion 92. Even in such a configuration, the maximum stress that holding portions 841 and 842 apply to paper stack B is reduced, and becomes half or less of the maximum stress that tooth row 90 applies to paper stack B.

[0064] Incidentally, when the paper stack B is partially deformed to perform the binding process, the paper P is generally deformed at the portion where the teeth of the binding member contact, and the visibility of the image formed on that portion is reduced. In the present embodiment, by providing holding portions 841 and 842 at both ends, the portion deformed by the teeth 90 is concentrated, and the reduction in the visibility of the image formed on the paper P is suppressed.

[0065] <Second embodiment> 10 is a diagram for explaining the binding member 81 in the second embodiment. In the above-described first embodiment, the holding portions 841, 842 were located at both ends of the tooth row 90. This second embodiment is characterized in that a holding portion is provided between the tooth rows 90. In this second embodiment, the same reference numerals are used for the same configurations as those in the first embodiment, and detailed description thereof will be omitted.

[0066] 10, in the upper teeth 83A and the lower teeth 83B, one protrusion 95 and the other protrusion 96 are provided at two locations between the tooth rows 90. As a result, the upper teeth 83A and the lower teeth 83B have three tooth rows 90, with the protrusions 95, 96 lined up between them. Moreover, protrusion 95 protrudes in the direction in which convex portion 91 protrudes, and has an apex 951 at its tip in the protruding direction. Similarly, protrusion 96 protrudes in the direction in which convex portion 91 protrudes, and has an apex 961 at its tip in the protruding direction.

[0067] 10, the apex 951 of the upper tooth 83A and the apex 961 of the lower tooth 83B face each other and are formed by planes that are approximately parallel to each other. The apex 951 and the apex 961 form the holding portion 843. Similarly, the apex 961 of the upper tooth 83A and the apex 951 of the lower tooth 83B face each other and are formed by planes that are approximately parallel to each other. The apex 951 and the apex 961 form the holding portion 844. Furthermore, when the upper teeth 83A advances a predetermined amount by the advancing / retracting mechanism 51A (see FIG. 4) while the stack of paper-sheets B is sandwiched, the gap between the holding portions 843 and 844 becomes G4. This gap G4 becomes smaller than the original thickness T of the stack of paper-sheets B.

[0068] With the above-mentioned configuration, the holding portions 843 and 844 in the second embodiment, like the holding portions 841, 842 in the first embodiment, hold the stack of paper B during the binding process on the stack of paper B, and suppress misalignment or tilt of the upper teeth 83A or the lower teeth 83B.

[0069] <Third embodiment> 11 is a diagram for explaining a binding member 81 in the third embodiment. This third embodiment is characterized in that a holding portion is provided in the central portion including the center O of the length in the direction in which the tooth rows 90 are arranged. In this third embodiment, the same reference numerals are used for the same configurations as those in the first embodiment, and detailed description thereof will be omitted.

[0070] 11, in the upper teeth 83A and the lower teeth 83B, the protruding portion 97 is provided in the central portion including the center O of the length in the direction in which the tooth rows 90 are arranged. As a result, the upper teeth 83A and the lower teeth 83B have two tooth rows 90, with the protruding portion 97 arranged between them. Further, the protruding portion 97 protrudes in the same direction as the convex portion 91 protrudes, and has an apex 971 at the tip in the protruding direction.

[0071] 11, the apex 971 of the upper tooth 83A and the apex 971 of the lower tooth 83B face each other and are formed of flat surfaces that are approximately parallel to each other. Furthermore, when upper teeth 83A advances a predetermined amount by advancing / retracting mechanism 51A (see FIG. 4) while sandwiching stack of paper-sheets B, the gap of holding portion 845 becomes G5. This gap G5 becomes smaller than the original thickness T of stack of paper-sheets B.

[0072] With the above-mentioned configuration, the holding section 845 in the third embodiment, like the holding sections 841, 842, 843, and 844 in the first and second embodiments, holds the stack of paper B during the binding process on the stack of paper B, and suppresses misalignment or tilt of the upper teeth 83A or the lower teeth 83B.

[0073] <Modification> In each of the above-described embodiments, the protrusions 93, 94, 95, 96, and 97 constituting the holding portions 841, 842, 843, 844, and 845 are all configured to be lower than the apex of the convex portion 91 and higher than the base portion 41. However, as long as the holding function can be achieved, the protrusions 93, 94, 95, 96, and 97 may be configured such that one of the opposing protrusions is not protruding and the other is higher than the apex of the convex portion 91. However, by making both opposing protrusions lower than the apex of the convex portion 91 and higher than the base portion 41 as in each of the above-described embodiments, it becomes easier to insert the stack of paper-sheets B between the upper teeth 83A and the lower teeth 83B.

[0074] In addition, in each of the above-described embodiments, the lower teeth 83B are configured to have the same tooth shape as the upper teeth 83A. However, the shapes of the upper teeth 83A and the lower teeth 83B may be different. Furthermore, the number of holding portions 841, 842, 843, 844, 845 in each of the above embodiments is not limited to the above examples, and may be increased as appropriate. [Explanation of symbols]

[0075] 1...image forming apparatus, 2...post-processing device, 22...finisher unit, 41...base, 51...stitching unit, 51A...advance / retraction mechanism, 60...paper stacking section, 65...alignment member, 80...stacker, 81...stitching member, 83A...upper teeth, 83B...lower teeth, 90...tooth row, 91...convex portion, 92...concave portion, 93,94,95,96,97...protruding portion, 100...image forming unit, 500...image forming system, 841,842,843,844,845...holding portion, 931,941,951,961,971...top, B...paper stack, G1,G2,G3,G4,G5...gaps, P...paper, T...thickness of paper stack, W,W1,W2...tooth width

Claims

1. upper teeth having a tooth row for forming unevenness on a recording material stack; a lower tooth paired with the upper tooth, the lower tooth having a tooth row for forming irregularities on the recording material bundle; a holding portion that holds the recording material stack at a location different from a location having a binding function between the upper teeth and the lower teeth during a binding process using the upper teeth and the lower teeth, The holding portion is an upper teeth protruding portion that is arranged in line with the row of teeth of the upper teeth and has a first surface that is lower than the top of the row of teeth and higher than the base of the row of teeth and parallel to the base, and a lower teeth protruding portion that is arranged in line with the row of teeth of the lower teeth and has a second surface that is lower than the top of the row of teeth and higher than the base of the row of teeth and parallel to the base, and when binding is performed by the upper teeth and the lower teeth, the recording material stack is sandwiched and held by the first surface and the second surface. A binding device characterized by:

2. The binding device according to claim 1 , wherein the retaining portions are provided at both ends of the tooth row of the upper teeth and the tooth row of the lower teeth.

3. a load means for applying a predetermined load to the recording material bundle sandwiched between the upper teeth and the lower teeth during the binding process, a maximum stress applied to the recording material stack by the holding portion in a state in which the load is applied by the loading means is smaller than a maximum stress applied to the recording material stack by the tooth row of the upper teeth and the tooth row of the lower teeth in a state in which the load is applied.

2. The binding device according to claim 1, characterized in that:

4. The binding device according to claim 3, characterized in that the maximum stress applied to the recording material stack by the holding portion when the load is applied by the loading means is less than half of the maximum stress applied to the recording material stack by the tooth row of the upper teeth and the tooth row of the lower teeth when the load is applied.

5. upper teeth including a tooth row for forming irregularities on a recording material stack, and an upper tooth protruding portion arranged in line with the tooth row, the upper tooth protruding portion having a first surface parallel to the base of the tooth row at a position lower than a top of the tooth row and higher than a base of the tooth row; a lower tooth comprising: a tooth row for forming irregularities on the recording material bundle; and a lower tooth protruding portion arranged in line with the tooth row, the lower tooth protruding portion having a second surface parallel to the base portion of the tooth row at a position lower than a top portion of the tooth row and higher than a base portion of the tooth row; a load means for applying a predetermined load to the recording material stack sandwiched between the upper teeth and the lower teeth, a gap between the first surface of the upper teeth protrusion portion and the second surface of the lower teeth protrusion portion in a state in which the stack of recording materials is sandwiched between the upper teeth and the lower teeth and the load is applied by the load means is smaller than a thickness of the stack of recording materials in a state in which the load is not applied. A binding device characterized by:

6. a gap between the first surface of the upper teeth protrusion portion and the second surface of the lower teeth protrusion portion in a state in which the stack of recording materials is sandwiched between the upper teeth and the lower teeth and the load is applied by the load means is larger than a narrowest gap between the tooth row of the upper teeth and the tooth row of the lower teeth in the state in which the load is applied.

6. The binding device according to claim 5, characterized in that

7. The binding device according to claim 6, characterized in that a gap between the first surface of the upper tooth protrusion and the second surface of the lower tooth protrusion when the stack of recording materials is clamped between the upper teeth and the lower teeth and the load is applied by the loading means is 1.7 to 2.5 times larger than the narrowest gap between the tooth row of the upper teeth and the tooth row of the lower teeth when the load is applied.

8. 6. The binding device according to claim 5, characterized in that a stress determined by a width in a direction in which the tooth rows of the upper teeth and the tooth rows of the lower teeth are aligned at a portion where the first surface of the upper tooth protrusion portion and the second surface of the lower tooth protrusion portion face each other is smaller than a maximum stress applied to the stack of recording materials by the tooth rows of the upper teeth and the tooth rows of the lower teeth when the stack of recording materials is clamped between the upper teeth and the lower teeth and the load is applied by the loading means.

9. The width of the facing portions in the said direction is 4 to 12% of the smaller of the sum of the widths of the upper tooth protrusion and the tooth row of the upper teeth in the said direction and the sum of the widths of the lower tooth protrusion and the tooth row of the lower teeth in the said direction. The binding device according to claim 8 .

10. upper teeth including a tooth row for forming irregularities on a recording material stack, and an upper tooth protruding portion arranged in line with the tooth row, the upper tooth protruding portion having a first surface parallel to the base of the tooth row at a position lower than a top of the tooth row and higher than a base of the tooth row; a lower tooth protruding portion having a second surface parallel to the base of the tooth row and located lower than the top of the tooth row and higher than the base of the tooth row; and a lower tooth paired with the upper tooth; A binding member, characterized in that, during binding processing by said upper teeth and said lower teeth, said stack of recording materials is sandwiched and held by said first surface and said second surface.

11. an image forming unit that forms an image; a conveying section that conveys a recording material on which an image has been formed by the image forming section; upper teeth that contact the recording material bundle from one direction of the recording material bundle conveyed by the conveying section and staple the recording material bundle without a staple; and lower teeth that face the upper teeth and contact the stack of recording materials from another direction to staple the stack of recording materials without a staple, The upper teeth and the lower teeth are a tooth row for forming irregularities on the recording material stack; a holding portion that holds the recording material stack at a location different from a location having a binding function between the upper teeth and the lower teeth during a binding process using the upper teeth and the lower teeth; Equipped with The holding portion is an upper teeth protruding portion that is arranged in line with the row of teeth of the upper teeth and has a first surface that is lower than the top of the row of teeth and higher than the base of the row of teeth and parallel to the base, and a lower teeth protruding portion that is arranged in line with the row of teeth of the lower teeth and has a second surface that is lower than the top of the row of teeth and higher than the base of the row of teeth and parallel to the base, and when binding is performed by the upper teeth and the lower teeth, the recording material stack is sandwiched and held by the first surface and the second surface. An image forming system comprising:

12. upper teeth having a tooth row for forming unevenness on a recording material stack; a lower tooth paired with the upper tooth, the lower tooth having a tooth row for forming irregularities on the recording material bundle; a holding portion that holds the recording material stack at a location different from a location having a binding function between the upper teeth and the lower teeth during a binding process using the upper teeth and the lower teeth, A binding device, characterized in that the retaining portion is provided between the row of teeth of the upper teeth and the row of teeth of the lower teeth.

13. 13. The binding device according to claim 12, wherein the holding portion is provided at a central portion including a center of length in a direction in which the tooth rows of the upper teeth and the tooth rows of the lower teeth are aligned.

14. upper teeth having a tooth row for forming unevenness on a recording material stack, and an upper tooth protruding portion arranged in parallel with the tooth row, the upper tooth protruding portion being lower than a top of the tooth row and higher than a base of the tooth row; a lower tooth paired with the upper tooth, the lower tooth pair including a tooth row for forming concaves and convexes on the recording material bundle, and a lower tooth protruding portion arranged next to the tooth row and lower than a top portion of the tooth row and higher than a base portion of the tooth row; having A binding member characterized in that the lower teeth have a shape that is rotated 180 degrees from the upper teeth around an axis that intersects the direction in which the tooth row of the upper teeth is arranged and the direction in which the upper tooth protruding portion protrudes.

15. The binding member according to claim 14, wherein the upper teeth and the lower teeth are molded using the same mold.

Images