JP7210140B2 - Resin member and image forming apparatus - Google Patents

Description

The present invention relates to a resin member incorporated in an image forming apparatus and other precision equipment and an image forming apparatus using the same, and more particularly to a resin member having holes used for mounting or positioning other parts. be.

Conventionally, in applications represented by electrical and electronic parts, optical parts, automobile parts, general equipment, etc., it is possible to mass-produce even complex shapes and reduce production costs. is widely used. As the performance of products has improved in recent years, some parts formed by injection molding require extremely high precision on the order of microns. It must also take into account fluctuations due to factors such as In order to suppress such accuracy fluctuations of parts, resin materials containing fibrous fillers are used.

When injection molding is performed using a resin material containing fibrous fillers, fiber orientation occurs in the resulting part. Due to the anisotropy of material shrinkage caused by this fiber orientation, there is a problem that the shape accuracy of holes used for bearings provided in parts deteriorates. In such cases, a common countermeasure is to reduce the anisotropy of material shrinkage due to fiber orientation by arranging multiple gates evenly and concentrically with respect to the center of the hole and allowing the resin to flow evenly toward the hole. is performed on

However, in the case of a component having a complicated shape such as an attachment hole for another component or a positioning portion, the gate position is restricted and it is difficult to adopt the above-described gate arrangement. Furthermore, the arrangement of a plurality of gates as described above is not preferable in consideration of the environmental impact of material costs and waste materials.

In Patent Document 1, either one of the hole portion and the outer portion is primarily molded first, and then the previously molded portion is fixed in the mold and the remaining portion is secondarily molded. and integrate the two. In this method, when the outer portion is molded first, there is a problem that the combination of resins is restricted in order to ensure sufficient adhesion between the two. Also, if the part that will be the hole is molded first, the shape accuracy of the hole will deteriorate due to the uneven shrinkage derived from the fibrous reinforcing material contained in the outer part, and the desired accuracy cannot be obtained. There's a problem.

In Patent Literature 2, in a molded body obtained by integrally molding a housing portion with a cylindrical portion, a non-fibrous filler is added to the material of the molded body in order to increase the roundness of the cylindrical portion. However, there is an upper limit to the total amount of fillers that can be mixed with the resin material, and the content of fibrous fillers is reduced by blending non-fibrous fillers. As a result, the rigidity improvement effect of the fibrous filler is reduced, and the desired rigidity of the molded article may not be obtained.

In Patent Document 3, in order to improve accuracy characteristics such as cylindricity by manufacturing a resin bearing considering the orientation of the constituent materials, at least one of the mold constituent members forming the outer surface and the inner surface is used. Forming is performed by rotating in the circumferential direction. However, in this method, since a part of the mold is rotated, not only are there restrictions on the product shape due to restrictions on the mold structure, but also a complicated mold mechanism, a driving device for rotation, etc. are required. increase the mold cost.

In Patent Document 4, in order to provide a cylindrical molded product that can obtain high shape accuracy in injection molding of a resin containing a filler, the inner peripheral surface of the cylindrical molded product is provided with a filler for changing the orientation of the filler during injection molding. A concave portion is provided. In this method, if an attempt is made to form a shape on the inner diameter side of a cylindrical molded product, a mold having a portion that slides inward is required. However, for small-diameter parts such as the bearings of photoreceptors in copiers, it is not possible to adopt a mold structure having a sliding portion.

In Patent Document 5, in order to eliminate problems due to anisotropy when a resin material thermally expands or contracts, and to manufacture a cylinder having a substantially perfect circular inner peripheral surface shape, a cylinder having unevenness formed on the outer peripheral surface is used. Resin molding. However, this method imposes restrictions on the shape of the molded product. For example, in the case of a support including a bearing for a photoreceptor of a copier, the outer shape of the support cannot be cylindrical. It has become.

JP-A-60-283699 JP 2009-173865 A JP-A-2000-145786 JP-A-2002-370268 JP-A-2003-23311

The present invention has been made in view of the above-mentioned problems of the background art, and enables the manufacture of resin members having complicated shapes, and the resin members that can be manufactured with a simple mold structure while suppressing material costs. and to provide an image forming apparatus incorporating the same.

In order to solve the above problems, a resin member according to the present invention is formed of a tubular member, has a hole portion used for mounting or positioning other parts, supports the hole portion from the periphery, and has a predetermined shape. and a housing portion, wherein the resin material used for the housing portion contains a fibrous filler, the cylindrical member has a projection projecting from an outer peripheral surface, and the projection is a cylinder. are formed at two or more locations on the outer peripheral surface of the cylindrical member and extend radially with respect to the center of the cylindrical member; The resin that forms the housing portion is poured into the mold from one gate portion in a molten state to integrate the cylindrical member and the housing portion, and in the hole portion, the resin material containing the fibrous filler fills the protruding portion. enveloping.

According to the above resin member, since the tubular member has the protrusion projecting from the outer peripheral surface, when the molten resin is poured into the mold, the fibrous filler generated around the hole is oriented by the protrusion. To obtain a resin member capable of being disturbed, capable of relieving uneven shrinkage due to fiber orientation occurring around a hole, and achieving both a housing portion having high rigidity and a hole having good shape accuracy. can be done.
In addition, projections are formed at two or more locations on the outer peripheral surface of the tubular member, and the more projections there are, the greater the effect of disturbing the orientation of the fibrous filler.
In addition, since the protrusions extend radially with respect to the center of the cylindrical member, the effect of the protrusions to disturb the flow of the molten resin is enhanced.
In addition, since the resin material containing the fibrous filler envelops the protrusion in the hole, the cylindrical member is stably supported by the housing.

In still another aspect of the present invention, the following formula t≥t' is satisfied, where t is the thickness of the cylindrical member in the radial direction and t' is the thickness of the projection in the circumferential direction.
satisfy. In this case, it becomes easier to maintain the accuracy of the inner peripheral surface of the cylindrical member.

In still another aspect of the present invention, the following formula w≦T is satisfied, where w is the axial width of the protrusion and T is the axial thickness of the cylindrical member.
satisfy. In this case, it is possible to prevent the projection from being exposed on the molding surface of the housing, and the tubular member is reliably supported by the housing.

In still another aspect of the invention, the hole is formed with a circular opening. A circular opening can function as a bearing or the like.

In still another aspect of the present invention, projections are formed at equal intervals in the circumferential direction at two or more locations on the outer peripheral surface of the cylindrical member. In this case, the projections arranged at equal intervals can disturb the orientation of the fibrous filler in a well-balanced manner around the hole.

In still another aspect of the present invention, the hole is a bearing that rotatably supports a shaft member that is another component. In this case, the hole or tubular member functions as a slide bearing.

In still another aspect of the present invention, the tubular member and the housing portion are made of different materials. As for the cylindrical member, it is possible to select a material that exhibits its function while ensuring shape accuracy.

In still another aspect of the present invention, the hole portion is a bearing portion that rotatably supports a shaft member which is another component, and when μ is the dynamic friction coefficient of the bearing portion and Μ is the dynamic friction coefficient of the housing portion, the following The formula for μ＜Μ
satisfy.

In still another aspect of the present invention, the resin member is a part that constitutes a unit that can be attached to and detached from the apparatus main body of the image forming apparatus, and the housing portion has a projection shape or a hole shape that is used for positioning with the apparatus main body. have one or more.

In order to solve the above problems, an image forming apparatus according to the present invention includes the resin member described above and forms an image on a recording medium.

According to the image forming apparatus described above, the resin member achieves both the housing portion having high rigidity and the hole having good shape accuracy, so that more delicate images can be output.

It is a figure explaining the support component which is a resin-made member of embodiment, and components of the circumference|surroundings. FIG. 2 is a conceptual diagram illustrating a method of incorporating the support component shown in FIG. 1; 3 is a diagram illustrating an image forming apparatus incorporating the apparatus shown in FIGS. 1 and 2; FIG. (A) is a plan view of a tubular member embedded in the support component shown in FIG. 1, and (B) is a side view of the tubular member. 2A and 2B are conceptual cross-sectional views explaining a molding process of the support component shown in FIG. 1; FIG. FIG. 4 is a diagram for explaining the flow of molten resin during molding; (A) to (F) are diagrams for explaining a support component of a modified example.

Hereinafter, specific embodiments of the resin member and the like of the present invention will be described with reference to FIG. 1 and the like. The support component 10, which is a resin-made member of the embodiment, is a component incorporated in an image forming apparatus such as a copying machine.

The support component (resin member) 10 is a component for supporting the photoreceptor drum 40 and is a part of the photoreceptor unit 140 . The support component 10 is formed by a cylindrical member 21 and includes a hole portion 20 used for mounting or positioning other components, and a housing portion 30 supporting the hole portion 20 from its surroundings. The tubular member 21 is held so as to be embedded in the molten resin and integrated with the housing portion 30 when the housing portion 30 is molded. The hole portion 20 or the cylindrical member 21 functions as a sliding bearing type bearing portion, and rotatably supports a photoreceptor shaft 41 provided on the photoreceptor drum 40 .

The tubular member 21 and the housing portion 30 are made of different materials. For the cylindrical member 21, it is desirable to select a material that has high shape accuracy and reduced frictional resistance. For the housing part 30, it is desirable to select a material that can ensure shape accuracy while having high strength or rigidity. When the coefficient of dynamic friction of the tubular member 21, which is the bearing portion, is μ, and the coefficient of dynamic friction of the housing portion 30 is Μ, the following formula (1)
μ<Μ … (1)
Materials are selected to satisfy Specifically, PBT (polybutylene terephthalate) resin, POM (polyacetal) resin, PPS (polyphenylene sulfide) resin, etc. can be used as the material of the cylindrical member 21, and PC (polycarbonate) resin and other resin materials can be used. A material added with an additive that lowers the coefficient of friction can be used. As a material for the housing portion 30, a mixture of ABS resin and PC (polycarbonate) resin, a mixture of PC (polycarbonate) resin, PPS (polyphenylene sulfide) resin, or the like, mixed with a fibrous filler can be used. Here, materials such as glass fiber can be used as the fibrous filler.

The housing portion 30 has an opening corresponding to the hole portion 20 and positioning portions 31 and 32 having a hole shape or a projection shape. The positioning portions 31 and 32 are used to detachably fix the photosensitive unit 140 including the photosensitive drum 40 and the support member 10 to the main body of the image forming apparatus. The positioning portions 31 and 32 not only have openings 31a and 32a, but also have a three-dimensional shape around the openings 31a and 32a, so that the desired strength and arrangement are ensured after the photosensitive unit 140 is attached. It has become so. The housing portion 30 is also provided with ribs 35 that contribute to ensuring strength, openings 36 for attaching other accessories, and the like.

A charging device 61 , a developing device 62 , a cleaning device 63 and the like are arranged around the photosensitive unit 140 . The photosensitive unit 140, the charging device 61, the developing device 62, and the cleaning device 63 constitute an image forming unit 50 of the image forming apparatus. In the image forming unit 50, the charging device 61 includes a charging roller 61a and the like. The developing device 62 includes a developing roller 62a and the like. The cleaning device 63 includes a cleaning member 63a and the like. A laser beam LB from a laser scanning unit is incident on a region between the charging device 61 and the developing device 62 on the surface of the photosensitive drum 40 .

FIG. 2 is a conceptual diagram illustrating a method of incorporating the support component 10 into the image forming apparatus. The support component 10 cooperates with another support component 110 to support the cylindrical photosensitive drum 40 . The support component 110 has a structure similar to that of the support component 10 and includes a tubular member 21 and a housing portion 30 . Here, the support parts 10 and 110 are fixed to the frame 100a of the image forming apparatus 100 (see FIG. 3).

FIG. 3 is a conceptual diagram showing an image forming apparatus 100 incorporating the image forming unit 50 shown in FIG. The image forming apparatus 100 has four image forming units 50 corresponding to yellow (Y), magenta (M), cyan (C), and black (K). Adjacent to these imaging units 50, an optical scanning device 70 for exposure is also provided. The mechanism and principle for image formation in the image forming apparatus 100 of the embodiment are well known, and the description thereof is omitted here.

The shape of the tubular member 21 embedded in the support component 10 shown in FIG. 1 will be described with reference to FIGS. 4(A) and 4(B). The tubular member 21 has a cylindrical body portion 24 and a plurality of projections 25 projecting from an outer peripheral surface 24 b of the body portion 24 . The body portion 24 has a circular opening 24o inside the cylinder. A pair of end faces 24a of the body portion 24 extend perpendicular to the axis AX, and an inner peripheral surface 24d is a cylindrical surface extending parallel to the axis AX and serves as a bearing surface. In the illustrated example, three protruding portions 25 protruding radially from the outer peripheral surface 24b of the tubular member 21 or the body portion 24 are formed. That is, the three protrusions 25 radially extend with the center O of the cylindrical member 21 as a reference. When the radial thickness of the cylindrical member 21 or the main body portion 24 is t, and the circumferential thickness of the protrusion 25 is t', the following equation (2) is obtained.
t≧t′ (2)
The outer shape of the cylindrical member 21 is determined so as to satisfy Further, when the axial width of the protrusion 25 is w, and the axial thickness of the tubular member 21 or the main body portion 24 is T, the following equation (3) is obtained.
w≦T (3)
The outer shape of the cylindrical member 21 is determined so as to satisfy

When the outer shape of the tubular member 21 satisfies the above formula (2), the inner peripheral surface 24d is less likely to be deformed due to shrinkage of the resin, ie, a so-called sink defect, and the shape accuracy of the inner peripheral surface 24d can be easily maintained. Further, when the outer shape of the tubular member 21 satisfies the above formula (3), it is possible to prevent the protrusion 25 from being exposed to the molding surface of the housing portion 30, and the tubular member 21 is not supported by the housing portion 30. be certain.

The three protrusions 25 are provided at regular intervals along the outer peripheral surface 24b of the tubular member 21 or the body portion 24. As shown in FIG. This facilitates maintaining the shape of the cylindrical member 21 . However, it is not essential to make the intervals between the protrusions 25 equal, and appropriate modifications can be made according to the application and specifications of the support component 10 . Moreover, it is not necessary to align all the shapes of the three protrusions 25 . The tubular member 21 is an injection-molded product, and the protrusion 25 may have gate traces 25f. Also, the location where the gate mark 25f is formed is not limited to the side surface.

Injection molding of the support component 10 will now be described with reference to FIGS. 5(A) and 5(B). The molding device 200 has a mold 2 for injection molding the support part 10 . The mold 2 has a first mold 2a and a second mold 2b. In addition to the mold 2, the molding apparatus 200 uses a drive mechanism for opening, closing, and clamping the mold while supporting the mold 2, and a heater provided in the mold 2, although not shown. and a temperature control device for controlling the temperature of the mold 2, and a control unit for integrally controlling these operations.

First, as shown in FIG. 5A, the first mold 2a and the second mold 2b are heated to a predetermined temperature (eg, 50° C.). In this state or in advance, the cylindrical member 21, which is an element of the support part 10, is set in a proper position between the first and second molds 2a, 2b to clamp the molds 2a, 2b. Here, the cylindrical member 21 is positioned close to the transfer surfaces PS of both the molds 2a and 2b, sandwiched between the molds 2a and 2b, and positioned within the cavity CV. At this time, the positioning of the cylindrical member 21 can be made more precise by providing the convex portion 2j on the second mold 2b, for example. A biasing member may be provided on one of the molds 2a and 2b to press the cylindrical member 21 against the other.

Thereafter, as shown in FIG. 5B, the molten resin RM is heated to a predetermined temperature (for example, 250° C.) and injected into the cavity CV. The molten resin RM is obtained by mixing and dispersing a fibrous filler in a basic resin material. The molten resin RM flows in the cavity CV, fills the circumference of the cylindrical member 21, and spreads to every corner in the cavity CV, completing the injection of the molten resin RM. The molding die 2 is set at a target temperature during and after the injection of the molten resin RM, and the molten resin RM cooled by heat radiation in the molding die 2 after the injection of the molten resin RM is completed is rapidly solidified. A molded product MP is molded. After that, although illustration is omitted, the second mold 2b on the movable side is released, and the molded product MP is taken out as the support component 10 by an ejector pin or the like. Here, the end surface 24 a and the inner peripheral surface 24 d of the body portion 24 of the tubular member 21 of the support component 10 are exposed to the outside of the support component 10 .

FIG. 6 is a diagram for explaining the flow state of the molten resin RM during molding of the molded article MP, that is, the support component 10. As shown in FIG. The flow FL of the molten resin RM spreads radially from the gate portion GP, but in the vicinity of the opening where the cylindrical member 21 is located, a vortex is formed by a plurality of projecting portions 25 projecting from the outer peripheral surface 24b of the cylindrical member 21. The elongated fibrous filler mixed in the molten resin RM is also arranged in a spiral. As a result, the fibrous filler is uniformly distributed in the molten resin RM filling the periphery of the cylindrical member 21 without orientation. As a result, the molded product MP, that is, the support component 10, is reduced in uneven shrinkage due to fiber orientation around the cylindrical member 21. FIG. If the fiber orientation remains in a large amount, the contraction rate differs between the direction parallel to the fiber orientation and the direction perpendicular to the fiber orientation. It becomes difficult to prevent this.

FIGS. 7A to 7F are diagrams for explaining modifications regarding the shape of the cylindrical member 21. FIG. The tubular member 21 shown in FIG. 7(A) has two protrusions 25 that protrude at regular intervals along the outer peripheral surface 24b of the body portion 24. The tubular member 21 shown in FIG. It has four protrusions 25 protruding at regular intervals along the outer peripheral surface 24b of the body portion 24. As shown in FIG. A tubular member 21 shown in FIG. 7C has a rectangular tubular main body portion 24 and four protrusions 25 protruding from four side surfaces 124b forming the outer peripheral surface. The tubular member 21 shown in FIG. 7(D) is a modification of the tubular member 21 shown in FIG. 7(C). It has two protrusions 25 that The tubular member 21 shown in FIG. 7E has a triangular tubular main body portion 24 and three protrusions 25 protruding from three side surfaces 124b forming the outer peripheral surface. The tubular member 21 shown in FIG. 7(F) is a modification of the tubular member 21 shown in FIG. 7(E). It has two protrusions 25 .

According to the support component 10, which is a resin member of the present embodiment, the cylindrical member 21 has the protrusion 25 that protrudes from the outer peripheral surface 24b. The housing portion 30 can disturb the orientation of the fibrous filler generated around the hole portion 20 by the portion 25, can alleviate uneven shrinkage due to the fiber orientation generated around the hole portion 20, and has high rigidity. , the support component (resin member) 10 which is compatible with the hole portion 20 having good shape accuracy can be obtained.

Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. For example, the number of protrusions 25 provided on the cylindrical member 21 may be 5 or more, but since the runner loss increases as the number of protrusions 25 increases, it is generally desirable to set the number to 5 or less.

In the above embodiment, the resin member is the support component 10 for the photoreceptor drum 40 incorporated in the image forming apparatus 100, but the resin member is not limited to the photoreceptor drum 40, and may be other parts. , and a structure in which the tubular member 21 described above is embedded in other parts. Furthermore, the resin member can be applied not only to the image forming apparatus but also to various devices such as a built-in component of a camera. In this case, the shape of the support component 10 is modified to suit the application.

The main body portion 24 of the tubular member 21 is not limited to a triangular or square tubular shape, and may have various polygonal tubular shapes.

DESCRIPTION OF SYMBOLS 2... Mold 2a, 2b... Mold 2j... Convex part 10, 110... Support part 20... Hole part 21... Cylindrical member 24... Body part 24a... End surface 24b... Outer peripheral surface 24d Inner peripheral surface 24o Opening 25 Protrusion 25f Gate mark 30 Housing portion 31, 32 Positioning portion 31a, 32a Opening 35 Rib 36 Opening 40 Photoreceptor Drum 41 Photoreceptor shaft 50 Image forming unit 61 Charging device 62 Developing device 63 Cleaning device 70 Optical scanning device 100 Image forming device 100a Frame 110 Supporting parts , 140... Photosensitive unit, 200... Molding device, AX... Shaft, CV... Cavity, GP... Gate part, MP... Molded product, PS... Transfer surface, RM... Molten resin

Claims (10)

a hole formed by a tubular member and used for mounting or positioning other parts;
A resin member including a housing portion having a predetermined shape and supporting the hole portion from the periphery,
The resin material used for the housing part contains a fibrous filler,
The cylindrical member has a protrusion that protrudes from the outer peripheral surface,
The protrusions are formed at two or more locations on the outer peripheral surface of the tubular member and extend radially with respect to the center of the tubular member,
With the cylindrical member previously fixed at a predetermined position in the mold for forming the housing portion, the resin forming the housing portion is poured into the mold in a molten state from one gate portion to form the tubular shape. The member and the housing part are integrated,
A resin member, wherein the resin material containing the fibrous filler envelops the protrusion in the hole. When the thickness of the cylindrical member in the radial direction is t, and the thickness of the protrusion in the circumferential direction is t', the following formula t≧t'
2. The resin member according to claim 1, wherein: When the width of the protrusion in the axial direction is w and the thickness of the cylindrical member in the axial direction is T, the following formula w≤T
The resin member according to any one of claims 1 and 2, wherein: 4. The resin member according to claim 1, wherein a circular opening is formed in said hole. 5. The resin member according to claim 4, wherein the protrusions are formed at two or more locations on the outer peripheral surface of the cylindrical member at equal intervals in the circumferential direction. The resin member according to any one of claims 1 to 5, wherein the hole portion is a bearing portion that rotatably supports the shaft member that is the other component. The resin member according to any one of claims 1 to 6, wherein the cylindrical member and the housing portion are made of different materials. The hole portion is a bearing portion that rotatably supports the shaft member, which is the other component.
8. The resin member according to claim 7, wherein: The resin member is a component that constitutes a unit that can be attached to and detached from an apparatus main body of the image forming apparatus,
The resin member according to any one of claims 1 to 8, wherein the housing portion has one or more protrusion shapes or hole shapes used for positioning with the device main body. An image forming apparatus comprising the resin member according to any one of claims 1 to 9, and forming an image on a recording medium.

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