Die molding, pressing device, sheet conveying device, and image forming apparatus

Abstract

To provide a die molding that can prevent an increase in the size of a die cutting part, a pressing device, a sheet conveying device, and an image forming apparatus.SOLUTION: A die molding has: a sheet facing surface part 95 that intersects a surface on which an engagement boss 93 is formed and faces a side face of the engagement boss 93; and a hole-shape or groove-shape die cutting part 94 that is provided on the sheet facing surface part for cutting a die forming a part of the engagement boss 93. Lightening parts 93a are formed respectively on both sides in an X-direction of the engagement boss 93 on a side of the die cutting part 94. Ends X2 in the X-direction of the lightening parts on a side of the die cutting part are located on the outermost side of the engagement boss 93 in the X-direction.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a die-formed product, a pressing device, a sheet conveying device, and an image forming apparatus.

Background Art

[0002] Conventionally, a die-formed product having a boss with a knockout portion is known.

[0003] Patent Document 1 describes, as the die-formed product, one in which knockout portions are provided at four locations and the occurrence of sink marks is suppressed by using a boss having a cross-sectional cross shape.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Depending on the shape of the die-formed product, the opening direction of the die may be perpendicular to the extending direction of the boss. Further, when the die-formed product has an opposing wall portion that intersects the surface on which the boss is formed and faces the side surface of the boss, and this opposing wall portion is perpendicular to the opening direction of the die, a die knockout portion in the shape of a hole or a groove is formed in this opposing wall portion. However, there has been a problem that the die knockout portion is large.

Means for Solving the Problems

[0005] In order to solve the above-described problems, the present invention provides, in a die-formed product having a boss with a knockout portion, an opposing wall portion that intersects the surface on which the boss is formed and faces the side surface of the boss, and a die knockout portion in the shape of a hole or a groove provided in the opposing wall portion for removing a die that forms a part of the boss, and the knockout portions are formed on both sides in a direction perpendicular to both the opening direction of the die removed from the die knockout portion side of the boss and the extending direction of the boss, and an end portion of the knockout portion on the die knockout portion side in the perpendicular direction is located at the outermost side of the boss in the perpendicular direction.

Effects of the Invention

[0006] According to the present invention, it is possible to suppress an increase in the mold release portion.

Brief Description of the Drawings

[0007]

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Embodiments for Carrying Out the Invention

[0008] The best mode for carrying out the present invention will be described below with reference to the drawings. A person skilled in the art can easily make changes and modifications to the present invention within the scope of the claims to form other embodiments, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode in this invention and does not limit the scope of the claims.

[0009] Hereinafter, as an image forming apparatus to which the present invention is applied, an electrophotographic printer (hereinafter simply referred to as a printer) that forms an image by an electrophotographic method will be described. Fig. 1 is a schematic configuration diagram showing a printer according to an embodiment. The printer shown in Fig. 1 is a monochrome printer. A process cartridge 1 as a detachable unit is detachably mounted on the apparatus main body 100. The process cartridge 1 includes a photosensitive member 2 as an image carrier that carries an image on its surface, and a charging roller 3 as a charging means for charging the surface of the photosensitive member 2. Further, the process cartridge includes a developing device 4 as a developing means for visualizing a latent image on the photosensitive member 2, a cleaning blade 5 as a cleaning means for cleaning the surface of the photosensitive member 2, and the like. In addition, an LED head array 6 as an exposure means for exposing the surface is disposed around the photosensitive member 2.

[0010] Further, a toner cartridge 7 as a developer container is detachably provided in the process cartridge 1. The toner cartridge 7 has a developer storage portion 8 in its container main body 22 for storing toner, which is a developer to be supplied to the developing device 4. Furthermore, the toner cartridge 7 of the present embodiment also integrally has a developer recovery portion 9 for recovering the toner (waste toner) removed by the cleaning blade 5.

[0011] The printer also includes a transfer unit 10 that transfers an image onto a sheet material as a transfer material, a sheet feeding device 11 that feeds the sheet material, a sheet conveying device 40 that conveys the sheet material, a fixing device 12 that fixes the image transferred onto the sheet material, and a sheet discharging device 13 that discharges the sheet material outside the device.

[0012] The transfer unit 10 includes a transfer roller 14 as a transfer member rotatably supported by a transfer frame 30. The transfer roller 14 is in contact with the photoreceptor 2 in a state where the process cartridge 1 is mounted on the apparatus main body 100, and a transfer nip is formed at the contact portion between the two. Further, the transfer roller 14 is connected to a power supply, and a predetermined direct current voltage (DC) and / or alternating current voltage (AC) is applied thereto.

[0013] The sheet feeding device 11 includes a sheet feeding cassette 15 that houses the sheet material P, and a sheet feeding roller 16 that feeds the sheet material P housed in the sheet feeding cassette 15. Further, on the downstream side in the sheet conveying direction with respect to the sheet feeding roller 16, a pair of registration roller pairs 17 as timing rollers that measure the conveyance timing and convey the sheet material to the secondary transfer nip are provided. Note that examples of the sheet material P include thick paper, postcards, envelopes, plain paper, thin paper, coated paper (such as coated paper and art paper), tracing paper, OHP sheets, OHP films, and the like.

[0014] The fixing device 12 includes a fixing roller 18 and a pressure roller 19. The fixing roller 18 is heated by an infrared heater 23 installed inside the fixing roller. The pressure roller 19 is pressed toward the fixing roller 18 and contacts the fixing roller 18, and a fixing nip is formed at the contact portion.

[0015] The sheet discharging device 13 includes a pair of sheet discharging rollers 20. The sheet material discharged outside by the sheet discharging rollers 20 is loaded onto a sheet discharging tray 21 formed by denting the upper surface of the apparatus main body 100.

[0016] Next, with reference to FIG. 1, the basic operation of the printer according to this embodiment will be described. When the image forming operation is started, the photoreceptor 2 of the process cartridge 1 is rotationally driven clockwise in FIG. 1, and the surface of the photoreceptor 2 is uniformly charged to a predetermined polarity by the charging roller 3. Based on the image information input from an external device, light is irradiated from the LED head array 6 onto the charged surface of the photoreceptor 2, and an electrostatic latent image is formed on the surface of the photoreceptor 2.

[0017] By supplying toner to the electrostatic latent image thus formed on the photoreceptor 2 by the developing device 4, the electrostatic latent image is visualized (made visible) as a toner image.

[0018] Also, when the image forming operation is started, the transfer roller 14 is rotationally driven, and a transfer electric field is formed between the transfer roller 14 and the photoreceptor 2 by applying a predetermined direct current voltage (DC) and / or alternating current voltage (AC) to the transfer roller 14.

[0019] At the lower part of the apparatus main body 100, the paper feed roller 16 starts rotational drive, and the sheet material P is fed out from the paper feed cassette 15. The fed sheet material P is temporarily stopped from being conveyed by the registration roller pair 17 of the sheet conveying device 40.

[0020] Thereafter, the rotational drive of the registration roller pair 17 is started at a predetermined timing, and the sheet material P is conveyed to the transfer nip in accordance with the timing when the toner image on the photoreceptor reaches the transfer nip. Then, by the above transfer electric field, the toner image on the photoreceptor 2 is collectively transferred onto the sheet material P serving as the transfer body. Also, the residual toner on the photoreceptor that could not be transferred onto the sheet material P is removed by the cleaning blade 5, and the removed toner is conveyed to and recovered by the developer recovery unit 9.

[0021] Thereafter, the sheet material P onto which the toner image has been transferred is conveyed to the fixing device 12, and the toner image on the sheet material P is fixed to the sheet material P in the fixing device 12. Then, the sheet material P is discharged outside the apparatus by a pair of paper discharge rollers 20 and stocked on the paper discharge tray 21.

[0022] On the side surface of the apparatus main body 100 (the right side surface in the figure), an opening / closing cover 37 that can be opened and closed in the direction of the arrow in the figure is provided. By opening this opening / closing cover 37, the process cartridge 1 is taken out from the apparatus main body through the opened opening.

[0023] FIG. 2 is a perspective view showing the periphery of the resist roller pair 17 of the sheet conveying device 40, and FIG. 3 is a top view looking down on the periphery of the resist roller pair 17. The resist roller pair 17 includes three driving rollers 17a provided at a predetermined interval in the axial direction, and three driven rollers 17b provided corresponding to each driving roller 17a. The three driving rollers 17a are attached to the driving shaft 41 so as to rotate integrally with the driving shaft 41.

[0024] On the other hand, the three driven rollers 17b are supported so as to be rotatable relative to the support shaft 42, and each driven roller 17b is pressed toward the driving roller 17a side by a pressing mechanism 80 serving as a pressing device. The three pressing mechanisms 80 provided corresponding to each driven roller 17b serving as a pressed member include a pressing bracket 82 serving as a pressing member and a pressing spring 81.

[0025] The driving shaft 41 is rotatably supported by a conveying guide 90 which is a die-formed product and a spring holding member via a bearing, and the support shaft 42 is fixedly provided to the conveying guide 90 so as not to rotate.

[0026] A driving gear 62 that meshes with a motor gear 61a of a conveying motor 61 serving as a driving source is attached to one end of the driving shaft 41 so as to rotate integrally with the driving shaft 41. Thereby, each driving roller 17a is rotationally driven by the driving force of the conveying motor 61.

[0027] FIG. 4 is a cross-sectional view taken along line A-A of FIG. 3, and FIG. 5 is a cross-sectional view taken along line E-E of FIG. 3. On both axial sides of the pressing bracket 82 of the pressing mechanism 80, support protrusions 82a are provided, and each support protrusion 82a is rotatably supported by a support hole 92 provided in the conveying guide 90. Further, the pressing bracket 82 has a fitting portion 82b that fits into flange portions 71 provided at both ends of the driven roller 17b.

[0028] The pressing spring 81 is a coil spring. As shown in FIG. 5, one end of the pressing spring 81 is engaged with an engagement boss 93 (see FIG. 5) provided on the conveying guide 90. The pressing spring 81 is attached in a compressed state between the conveying guide 90 and the pressing bracket 82, and biases the central portion of the pressing bracket 82 in the direction of arrow F1 in FIG. 4. By this pressing spring 81, the pressing bracket 82 is biased to rotate counterclockwise in FIG. 4 with the support protrusion 82a as a fulcrum. As a result, the flange portion 71 of the driven roller 17b is pressed in the direction shown by arrow F2 in the figure by the fitting portion 82b of the pressing bracket 82. As a result, the driven roller 17b contacts the driving roller 17a with a predetermined contact pressure, a conveying nip is formed, and the driven roller 17b rotates well in a driven manner with respect to the driving roller 17a.

[0029] Further, by the pressing spring 81 biasing the center of the pressing bracket 82, the flange portions 71 provided on both axial sides of the driven roller can be evenly pressed, and the pressure distribution generated between the driving roller and the driven roller can be made uniform in the X direction. Thereby, the occurrence of skewing and wrinkles of the paper can be suppressed.

[0030] The conveying guide 90 is a resin injection molded product (molded part). In order to suppress sink marks, as shown in FIG. 5, three cutout portions 93a are provided in the cylindrical engagement boss 93 to form a T-shaped cross section.

[0031] FIG. 6 is a schematic view of the conveying guide 90. As shown in FIG. 6, on a sheet facing surface portion 95 which is an opposing wall portion facing the sheet material of the conveyance guide 90, a plurality of guide ribs 91 extending in the sheet conveyance direction are provided at predetermined intervals in the axial direction (X direction). Further, at a location facing the engagement boss 93 of the sheet facing surface portion 95, there is a hole-shaped mold release portion 94 formed for removing the mold after forming the conveyance guide. Note that, as shown in FIG. 7, the mold release portion may be a groove-shaped mold release portion 194.

[0032] FIG. 8 is a schematic configuration diagram showing a conventional engagement boss 193. The conventional engagement boss 193 shown in FIG. 8 has a cross shape with cutout portions 193a formed at four locations in the circumferential direction, and the side surfaces 193c on both sides of the engagement boss 193 in the X direction are arc surfaces. The center X1 of the side surface 193c in the Z direction is shaped to be the outermost in the X direction of the engagement boss 193. With an engagement boss 193 having such a shape, there was a possibility that the mold release portion 94 would become large in the X direction (the length L2 of the mold release portion in the X direction is longer than the length L1 of the boss portion in the X direction), and the guide ribs 91 could not be arranged at equal intervals in the X direction. Hereinafter, the reason why the mold release portion 94 becomes large in the X direction will be described.

[0033] FIG. 9 is a schematic configuration diagram showing a mold structure for forming a conventional engagement boss 193. The engagement boss 193 of the conveyance guide is formed by aligning a first mold 101 and a second mold 102, which are stripping molds removed from the mold release portion 94, in the vertical direction (Z direction) of the sheet facing surface portion 95. The first mold 101 has a convex portion 101a protruding in the Z direction, and an engagement boss forming portion at the tip of the convex portion 101a. Further, the convex portion 101a has a draft angle of about 3° so as to be easily removed from the mold release portion 94 of the conveyance guide. Also, by providing a draft angle, when the second mold is displaced in the X direction with respect to the first mold, it can be positioned at a specified position by this draft angle.

[0034] As shown in Fig. 9, the parting line between the first mold 101 and the second mold 102 is set at the center X1 in the Z direction of the side surfaces 193c on both sides in the X direction of the engaging boss 193. This is because, as shown in Fig. 10, when the side surfaces 193c on both sides in the X direction of the engaging boss 193 are formed by the second mold 102, the side on the first mold side rather than the center X1 in the Z direction of the side surface 193c becomes an undercut portion Ud. As a result, the formed conveying guide 90 cannot be demolded from the second mold 102.

[0035] Also, in the conventional engaging boss 193, as shown in Fig. 9, the tip of the convex portion 101a of the first mold 101 needs to be shaped to extend in the X direction by Tmm from the end in the X direction of the portion forming the engaging boss 93. This is because, as shown in Fig. 11, when the end in the X direction of the tip of the convex portion 101a of the first mold 101 is the end in the X direction of the portion forming the engaging boss 193, a thin portion U is formed at the tip of the convex portion 101a. With such a thin portion U, cracks and chips are likely to occur in this thin portion U, and the durability of the first mold 101 decreases.

[0036] For these reasons, the conventional engaging boss 193 shown in Fig. 8 needs to be formed in a mold shape as shown in Fig. 9, and the convex portion 101a of the first mold 101 becomes larger in the X direction. As a result, after the forming of the conveying guide 90, the mold release portion 94 configured such that the convex portion 101a comes out becomes larger in the X direction.

[0037] Also, even when there are no cut-out portions on both sides in the X direction on the mold release portion 94 side of the engaging boss, similar to the above, the mold release portion 94 may become larger in the X direction, and there is a possibility that the guide ribs cannot be arranged at equal intervals in the X direction. This is because, as shown in FIG. 12, when the X-direction end portion of the tip of the convex portion 101a of the first mold 101 is set as the X-direction end portion of the portion forming the engaging boss 293, a thin-walled portion U is formed at the tip of the convex portion 101a, and the durability of the first mold 101 is reduced. Therefore, even when there are no cut-out portions on both sides in the X direction on the mold release portion 94 side of the engaging boss, the tip of the convex portion 101a of the first mold 101 has a shape extending in the X direction by Tmm from the X-direction end portion of the portion forming the engaging boss, and the convex portion 101a becomes larger in the X direction. As a result, the mold release portion 94 becomes larger in the X direction, and the guide ribs cannot be arranged at equal intervals in the X direction.

[0038] On the other hand, as shown in FIG. 5, in the engaging boss 93 of the present embodiment, cut-out portions 93a are formed on both sides in the X direction on the mold release portion 94 side of the engaging boss 93, and the X-direction end portions X2 of these cut-out portions 93a on the mold release portion 94 side are configured to be located on the outermost side in the X direction of the engaging boss 93.

[0039] Specifically, in the Z direction, by cutting out both sides in the X direction on the mold release portion 94 side up to the position of the center O1 of the engaging boss 93, the X-direction end portions X2 of the cut-out portions 93a on the mold release portion 94 side are configured to be located on the outermost side in the X direction of the engaging boss 93.

[0040] FIG. 13 is a schematic view of the mold structure forming the engaging boss 93 of the present embodiment. In the engaging boss 93 of the present embodiment, the X-direction end portion X2 of the cut-out portion 93a is located on the outermost side in the X direction of the engaging boss 93. Thereby, even when the side surfaces 93c on both sides in the X direction of the engaging boss 93 are formed by the second mold 102, no undercut portion is generated.

[0041] Further, thinning portions 93a are formed on both sides in the X direction on the mold release portion 94 side of the engaging boss 93 of the present embodiment. Thereby, even if the tip of the convex portion 101a is not extended in the X direction from the X-direction end portion of the portion forming the engaging boss 93, the thicknesses on both sides in the X direction of the tip of the convex portion 101a of the first mold 101 can secure the thickness T required for the mold strength. Thereby, the X-direction length of the tip of the convex portion 101a of the first mold 101 can be made substantially equal to the X-direction length of the engaging boss 93, and the enlargement of the convex portion 101a of the first mold 101 in the X direction can be suppressed. Thereby, the mold release portion 94 for removing the convex portion 101a of the first mold 101 can be suppressed from becoming large in the X direction. possible . As a result, it is possible to suppress the arrangement of the guide ribs 91 from being restricted by the mold release portion 94, and the guide ribs 91 can be arranged at equal intervals in the X direction.

[0042] The engaging boss 93 has thinning portions 93a on both sides in the X direction on the mold release portion 94 side, and the X-direction end portions X2 of these thinning portions 93a on the mold release portion 94 side may be located on the outermost side in the X direction. Therefore, as shown in FIG. 14, the engaging boss 93 may have a shape in which thinning portions 93a are provided only on both sides in the X direction on the mold release portion 94 side, or as shown in FIG. 15, thinning portions may be provided at four positions in the circumferential direction of the engaging boss 93 to form a substantially cross shape.

[0043] Further, as shown in FIG. 16, the side surfaces 93c on both sides of the engagement boss 93 in the X direction may be flat surfaces. Even in the shape shown in FIG. 16, the X-direction end X2 of the cutout portion 93a on the mold release portion 94 side is the outermost in the X direction, and the side surfaces on both sides of the engagement boss in the X direction can be formed by the second mold. However, in the configuration shown in FIG. 16, as shown in FIG. 17, the positioning of the pressing spring 81 in the X direction is performed at both ends X2 and X3 in the Z direction of the flat surface portion of the engagement boss 93, and the positioning portion of the engagement boss in the X direction is in line contact with the pressing spring 81. Since the engagement boss 93 is made of resin and the pressing spring 81 is made of metal, in such a configuration, deformation and shaving are likely to occur at both ends in the Z direction of the flat surface portion of the engagement boss 93 when the pressing spring is assembled, as compared with the case of surface contact with the pressing spring 81. If deformation or shaving occurs at both ends in the Z direction of the flat surface portion, positioning in the X direction cannot be achieved, and the pressure distribution generated between the driving roller and the driven roller may become non-uniform in the X direction, which may cause skewing or wrinkling of the paper.

[0044] Therefore, for example, as shown in FIG. 18, it is preferable to adopt a configuration in which positioning in the X direction and the Z direction can be performed on the arc-shaped side surface of the engagement boss 93. In the configuration shown in FIG. 18, as shown in FIG. 19, the pressing spring is positioned in the Z direction by two arc-shaped side surfaces 93c1 and 93c2 on the side opposite to the mold release portion side and the arc-shaped side surface 93c3 on the mold release portion side. Further, the pressing spring 81 is positioned in the X direction by the side surfaces of the two arc-shaped side surfaces 93c1 and 93c2 on the side opposite to the mold release portion side. Further, since these arc-shaped side surfaces 93c1, 93c2, and 93c3 for positioning the pressing spring 81 are in surface contact with the pressing spring 81, shaving and deformation are less likely to occur when the pressing spring is assembled. Therefore, in such a configuration, as shown in FIG. 18, even if deformation or shaving occurs at both ends in the Z direction of the flat surface of the side surfaces 93c on both sides of the engagement boss 93 in the X direction, the pressing spring 81 can be positioned in the X direction.

[0045] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims, unless otherwise particularly limited in the above description. For example, in the present embodiment, the engaging boss engages with the pressing spring 81 and positions the pressing spring 81, but the mating member that engages with the engaging boss is not limited to a spring.

[0046] What has been described above is an example, and specific effects are achieved for each of the following aspects. (Aspect 1) In a die-formed product provided with a boss such as an engaging boss 93 having a cutout portion 93a, an opposing wall portion such as a sheet opposing surface portion 95 that intersects the surface on which the boss is formed and faces the side surface of the boss, and a die removal portion 94 in the shape of a hole or groove provided in the opposing wall portion for removing the die that forms a part of the boss. Cutout portions are formed on both sides in the orthogonal direction (X direction) that is orthogonal to the opening direction (Z direction) of the die removed from the die removal portion on the die removal portion side of the boss and the extending direction (Y direction) of the boss, and the orthogonal direction end X2 of the cutout portion on the die removal portion side is located on the outermost side of the boss in the orthogonal direction (X direction). The portion of the die (hereinafter referred to as the ejection die) that forms the boss of the die-formed product such as the formed conveying guide 90 and is removed from the die removal portion 94 is the tip portion of the convex portion 101a of the ejection die 101 as shown in FIGS. 11 and 12. As shown in FIG. 12, in the case of a boss without a cutout portion on the die removal portion 94 side, thin portions U with a thin thickness are formed on both sides in the above-mentioned orthogonal direction (the direction orthogonal to both the extending direction (Y direction) of the boss and the opening direction (Z direction) of the ejection die: X direction) at the tip of the convex portion 101a of the ejection die 101. Further, even if there are cutout portions on both sides in the orthogonal direction (X direction) on the die removal portion 94 side of the boss, when the boss has the following shape, as shown in FIG. 11, thin portions U with a thin thickness are formed on both sides in the orthogonal direction (X direction) at the tip of the convex portion 101a of the ejection die 101. That is, as shown in FIG. 11, there is a shape in which there is a portion (X1 in FIG. 11) located on the outermost side of the boss in the orthogonal direction (X direction) on the upstream side in the opening direction (Z direction) of the ejection die from the orthogonal direction end X2 of the cutout portion. In the case of such a shape, the portion (X1 in FIG. 11) located on the outermost side of the boss in this orthogonal direction (X direction) becomes the parting line of the die, and thin portions U with a thin thickness are formed on both sides in the orthogonal direction (X direction) at the tip of the convex portion 101a of the ejection die 101. Thus, if there are thin portions U with a small thickness on both sides of the tip of the convex portion 101a of the knockout die in the orthogonal direction (X direction), there is a risk of cracks and chips occurring on both sides thereof. Therefore, conventionally, as shown in FIG. 9, the tip of the convex portion 101a of the knockout die is made larger than the boss in the orthogonal direction (X direction) so that thin portions do not occur on both sides of the tip of the convex portion 101a of the knockout die in the orthogonal direction (X direction). As a result, the die release portion 94 of the die-formed product becomes large. On the other hand, in the present embodiment, relief portions 93a are formed on both sides of the boss on the die release portion side in the orthogonal direction (X direction), and the end portions X2 of the relief portions 93a in the orthogonal direction (X direction) are positioned on the outermost sides of the boss 93 in the orthogonal direction (X direction). By positioning the end portions X2 of the relief portions 93a in the orthogonal direction (X direction) on the outermost sides of the boss 93 in the orthogonal direction (X direction), it becomes possible to form the side surfaces on both sides of the boss in the X direction with the other die (second die 102) that matches the knockout die. As a result, both ends of the boss forming portion at the tip of the convex portion 101a of the knockout die in the orthogonal direction (X direction) become the end portions X2 of the relief portions 93a in the orthogonal direction (X direction). And since the relief portions 93a are formed on both sides of the boss on the die release portion side in the orthogonal direction (X direction), as shown in FIG. 13, even if the length of the tip of the convex portion 101a of the knockout die in the orthogonal direction (X direction) is substantially the same as the outer diameter of the boss 93, sufficient thickness can be ensured on both sides of the tip of the convex portion 101a in the orthogonal direction (X direction). Thereby, it is possible to suppress the convex portion 101a from becoming large in the orthogonal direction (X direction), and it is possible to suppress the die release portion 94 from becoming large in the orthogonal direction (X direction).

[0047] (Aspect 2) In Aspect 1, bosses such as the engagement boss 93 are inserted into mating members such as a cylindrical compression spring 81 to position the mating members, and the mating members are positioned in the die opening direction (Z direction) and the orthogonal direction (X direction) by the arc-shaped side surfaces of the engagement boss. According to this, as described with reference to FIGS. 18 and 19, by forming the side surface of the engagement boss for positioning the mating member as an arc surface, surface contact is achieved with the mating member. As a result, compared to the case of line contact with the mating member, deformation and shaving when assembling the mating member to the boss can be suppressed. Thereby, the mating member can be favorably positioned in the mold opening direction (Z direction) and the orthogonal direction (X direction).

[0048] (Aspect 3) A spring holding member such as a conveyance guide 90 having a boss such as an engagement boss 93 with which a coil spring such as a pressing spring 81 engages, and a pressing device such as a pressing mechanism 80 that presses a pressed member such as a driven roller 17b with the biasing force of the coil spring, wherein the spring holding member is a mold-formed product described in Aspect 1 or 2. According to this, since the spring holding member is suppressed from having sink marks and is accurately molded, the coil spring can be accurately held by the spring holding member, and it becomes possible to evenly press the pressed member.

[0049] (Aspect 4) In Aspect 3, a coil spring such as a pressing spring 81 is disposed at the center of a pressing member such as a pressing bracket 82 that abuts on a pressed member such as a driven roller 17b and presses the pressed member. According to this, as described in the embodiment, the pressed member such as the driven roller 17b can be evenly pressed by the pressing bracket 82 that is a pressing member.

[0050] (Aspect 5) A sheet conveyance device including a driving roller 17a that is rotationally driven, a driven roller 17b that rotates with the driving roller 17a, and a pressing mechanism 80 that presses the driven roller 17b as a pressed member toward the driving roller 17a, wherein, as the pressing mechanism 80, the pressing device described in Aspect 3 or 4 is used. According to this, as described in the embodiment, the driven roller 17b abuts on the driving roller 17a with a predetermined contact pressure, a conveyance nip is formed, and the driven roller 17b can favorably rotate following the driving roller 17a.

[0051] (Aspect 6) In Aspect 5, the spring holding member is the conveyance guide 90 that guides the sheet, and a plurality of guide ribs 91 are provided on the surface opposite to the facing surface that faces bosses such as the engaging boss 93 of the facing surface portion. According to this, as described in the embodiment, the mold release portion provided in the facing surface portion can be made smaller, so that it is possible to suppress the occurrence of a problem that the guide ribs 91 cannot be arranged at desired positions due to the mold release portion.

[0052] (Aspect 7) In an image forming apparatus including a sheet conveyance device, the sheet conveyance device according to Aspect 5 or 6 was used as the sheet conveyance device. According to this, as described in the embodiment, the sheet can be conveyed well.

Explanation of Reference Numerals

[0053] 17: Resist roller pair 17a: Driving roller 17b: Driven roller 40: Sheet conveyance device 41: Driving shaft 42: Support shaft 61: Conveyance motor 61a: Motor gear 62: Driving gear 71: Flange portion 80: Pressing mechanism 81: Pressing spring 82: Pressing bracket 82a: Support protrusion 82b: Fitting portion 90: Conveyance guide 91: Guide rib 92: Support hole 93: Engaging boss 93a: Relief portion 94: Mold release portion 95: Sheet facing surface portion 101: First mold 101a: Protrusion 102: Second mold 193: Conventional engagement boss 193a: Cutout portion 293: Conventional engagement boss O1: Center of engagement boss P: Sheet material U: Thin portion Ud: Undercut portion

Prior art documents

Patent documents

[0054]

Patent Document 1

Claims

1. In a mold-formed product provided with a boss having a knockout portion, an opposing wall portion that intersects the surface on which the boss is formed and faces the side surface of the boss, and a mold release portion in the shape of a hole or groove provided in the opposing wall portion for removing the mold that forms a part of the boss, the knockout portions are formed on both sides in a direction orthogonal to both the opening direction of the mold removed from the mold release portion on the mold release portion side of the boss and the extending direction of the boss, A mold-formed product, wherein an end portion of the knockout portion on the mold release portion side in the orthogonal direction is located on the outermost side of the boss in the orthogonal direction.

2. In the mold-formed product according to Claim 1, the boss is inserted into a cylindrical mating member to position the mating member, and the mold-formed product is characterized in that the mating member is positioned in the opening direction of the mold and the orthogonal direction by the arcuate side surface of the boss.

3. In a pressing device including a spring holding member having a boss with which a coil spring engages and pressing a pressed member with the biasing force of the coil spring, the spring holding member is the mold-formed product according to Claim 1.

4. In the pressing device according to Claim 3, the coil spring is disposed at the center of a pressing member that abuts against the pressed member and presses the pressed member.

5. A driving roller that rotates, a driven roller that rotates with the driving roller, and a pressing mechanism that presses the driven roller as the pressed member toward the driving roller, In a sheet conveying device that conveys a sheet by the driving roller and the driven roller, the sheet conveying device is characterized in that the pressing device according to Claim 3 is used as the pressing mechanism.

6. In the sheet conveying device according to Claim 5, the spring holding member is a conveying guide that guides the sheet, and a plurality of guide ribs are provided on a surface opposite to the opposing surface of the opposing wall portion that faces the boss.

7. In an image forming apparatus including a sheet conveying device, the image forming apparatus is characterized in that the sheet conveying device according to Claim 5 is used as the sheet conveying device.

Images