JP2021006742A - Composite gear, cartridge, image forming device, molding mold, and method of manufacturing composite gear - Google Patents

Abstract

To securely unite a first member and a second member configuring a gear, and to reduce the possibility of breakage such as cracking due to shrinkage with time.SOLUTION: A composite gear (10) includes a first member (50) that has a rotary shaft portion and a disc-shaped web (55), and a second member (30) that has at least one or more engaging teeth on an outer periphery, and is supported by the web and is provided so as to surround the outer periphery of the first member. The composite gear is formed so that the outermost peripheral surface of the first member has a diametrical space between the first member and the second member, the innermost peripheral surface of the second member has a diametrical space between the first member and the second member, and at least one of the first member and the second member sandwiches the other of the first member and the second member from both sides in an axial direction of the rotary shaft portion.SELECTED DRAWING: Figure 1

Description

The present invention relates to composite gears, cartridges, image forming devices, molding dies, and methods for manufacturing composite gears.

Resin gears are incorporated as power transmission components in a wide range of mechanical products such as OA equipment such as copiers and printers, consumables such as ink cartridges, and small precision equipment such as digital cameras and video cameras. Conventionally, resin gears as high-precision power transmission parts have the accuracy of tooth tip circle size, meshing error (Japanese Industrial Standard JGMA 116-02) and tooth streak grade (JIS B 1702 based on ISO 1328). Standards are set according to the application and purpose. In particular, many resin gears used in high-quality mechanical products have improved quality by setting a small range of these accuracy standards.

However, in recent years, color printers and color copiers are required not only to have high quality but also to improve functional aspects such as low noise performance during driving and advanced printing performance. In the case of these devices, it is difficult to satisfy the requirements only by the conventional method of setting the gear accuracy standard width small, and the gear rotation transmission accuracy (JIS B 1702-3 Annex 1) and other movements It is also necessary to improve the accuracy.

For example, in the case of a beveled gear having inclined teeth, the events that deteriorate the rotation transmission accuracy are (1) poor gear tooth surface accuracy, (2) defective gear support, and (3). Problems such as deformation of gears during rotational drive are known.

Among these problems, (1) is considered to be caused by, for example, the specifications given to the tooth surface not being suitable for the usage environment, or the shape deterioration due to resin shrinkage during molding. (2) is considered to occur, for example, when the support shaft of the gear is eccentric or tilted with respect to the rotation shaft. It is considered that (3) is caused by the torque generated when the gear is actually incorporated into the mechanical product and rotated at a specific rotation speed. In the cases of (1) and (2) above, various standards such as tooth streak error accuracy (JIS B 1702) and coaxiality are set for the gear, and management is performed by adopting a gear that fits the standard. Is possible. On the other hand, since (3) is a problem caused by the dynamic environment of the gear, it may be difficult to avoid it by the accuracy standard under the static environment such as (1) and (2).

For example, the resin gear 70 as shown in FIGS. 13 (a) and 13 (b) has an annular rim 72 on which inclined teeth 71 (has teeth) are formed and a rotation arranged at the center of the gear. The support portion 74 is connected to the support portion 74 by a web 79. The rotation support portion 74 has a cylindrical shape and includes an inner diameter portion 81 and outer diameter portions 82 and 83. The structure of the rotary support portion differs depending on the configuration of the mechanical product, and the inner diameter portion 81 is supported by fitting a resin or metal shaft, the outer diameter portion 82 or 83, or both are supported as bearings. There is a configuration.

Normally, when such a resin gear 70 is rotationally driven, torque is generated, so that a torsional moment is generated in the rotary support portion 74. Further, when the resin gear 70 has inclined teeth 71, a component force is generated in the thrust direction due to the twisting component of the teeth. That is, a plurality of force components are generated around the axis of the rotation support portion.

Conventionally, this type of resin gear has been formed by using a resin material such as polyacetal, which has good slidability and high mechanical strength. However, due to the recent sophistication of mechanical products and the like, the force applied to the resin gears has increased, and the load on the rotary support portion has increased, so that deformation has often become a problem. Therefore, in recent years, a composite gear in which the rotation support portion is made of a highly rigid synthetic resin and the gear is made of a conventional polyacetal or the like has been proposed.

For example, FIGS. 14 (a), 14 (b), and 15 (a) to 15 (c) show a conventional configuration of a composite gear 40 made of two kinds of materials. The composite gear 40 includes a first member 60 (FIG. 14 (a)) having a rotation support portion 61 made of a highly rigid synthetic resin, and a second member 90 (FIG. 14 (a)) including a tooth portion 91. ), FIG. 15 (a) to (c)). The second member 90 is formed of a synthetic resin softer than the first member, and is integrated with the first member 60 so as to cover the outer periphery of the first member.

In the composite gear 40 of FIGS. 14 (a), 14 (b) and 15 (a) to 15 (c), the rotation support portion 61 of the first member 60 has an inner diameter hole 62 and outer diameter portions 63 and 64. Further, an inner web 65 covered with a second member is arranged on the outer peripheral side of the rotation support portion 61. As shown in FIGS. 15B and 15C, the second member 90 is provided with an outer web 92 that covers the inner web 65. In this way, by forming the first member 60 from a high-rigidity material, it is possible to suppress deformation due to the torsional moment and thrust component force generated during rotational drive, and the problem (3) described above is minimized. be able to. Further, by using a synthetic resin having good slidability for the second member 90, the rotational lubricity required for the gear can be obtained.

In such a composite gear 40, the rotation support portion by the first member 60 and the gear portion of the second member 90 must be firmly coupled. Conventionally, a manufacturing method in which the first member 60 and the second member 90 are manufactured separately and then combined by fastening or press-fitting may be used. However, this method has a problem that the accuracy tends to be lowered due to an error at the time of assembly, and further, extra equipment, parts, labor, and time are required for manufacturing.

Therefore, as another manufacturing method, a method has been proposed in which the first member is inserted into a mold and the second member is injection-molded to completely bring the two members into close contact with each other. According to this method, if the first member and the second member are not compatible with each other, they may be peeled off. Therefore, FIGS. 14 (a), 14 (b) and 15 (a) to 15 (c) show. It has a structure in which the first member is sandwiched between the second members like a compound gear. Further, the uneven portion 67 is added to the outermost periphery of the inner web 65 of the first member so that the phase shift does not occur due to the torque generated during rotation, and the adhesion strength in the rotation direction is also ensured. In any case, this type of composite gear requires adhesion strength in both the thrust direction and the rotational direction.

For example, Patent Document 1 proposes a configuration in which a tooth portion made of synthetic resin is integrally molded on the outer periphery of an insert member having a concave groove in the axial direction to achieve both rigidity and accuracy. Further, Patent Document 2 proposes a configuration in which a disk portion having an uneven portion formed is provided on a rotating shaft, and a gear is formed so as to cover the entire disk portion to improve the fixing strength between the rotating shaft and the gear. There is. Further, Patent Document 3 proposes a configuration for ensuring rigidity by engaging a convex portion provided on a side surface of a resin gear with a hole portion provided on a side surface of a metal plate.

Japanese Unexamined Patent Publication No. 2010-139041 Japanese Unexamined Patent Publication No. 2003-2124 Jikkenhei 4-124628

However, in a composite gear made of a plurality of different materials as described above, the stronger the bond between the members, the more the occurrence of cracks due to dimensional changes may become a problem. In this type of product, the gear portion is often made of a crystalline resin such as polyacetal having good slidability. For example, a crystalline resin such as polyacetal easily obtains slidability, but the amount of shrinkage with time is large because the molecules continue to crystallize even after molding. Therefore, a composite gear using this kind of crystalline resin for the gear portion tends to be easily distorted due to the difference in the amount of contraction. For example, in a composite gear as shown in FIGS. 14 (a), 14 (b) and 15 (a) to 15 (c), a fiber reinforced resin using polybutadiene terephthalate or the like for the first member 60 constituting the rotating shaft portion. In some cases, a polyacetal resin may be used for the second member 90. In that case, the shrinkage rate of the polyacetal resin is 1.6 to 2.0%, whereas the shrinkage rate of the fiber-reinforced resin using polybutadiene terephthalate or the like is about 0.2 to 0.8%, which is significantly different. .. Therefore, in the structures of FIGS. 14 and 15, since the outer web 92 of the second member 90 is formed so as to cover the inner web 65 of the first member 60, the first member 60 is the second member. A relationship is formed that inhibits the contraction of 90. Then, according to the material selection as described above, the mechanical strength of the second member 90 is weaker than that of the first member 60, and as the shrinkage progresses with time, the strain of the second member 90 becomes large and cracks occur. May occur.

Normally, shrinkage over time progresses relatively slowly in a living environment at room temperature, so it takes decades to hundreds of years for cracks to occur, and it is unlikely to become a problem. However, depending on the equipment in which the gear is used, it may be used in an environment where the ambient temperature is high, in which case the rate of shrinkage over time is accelerated and cracks may occur in several years.

The above-mentioned Patent Document 1 proposes a configuration in which a tooth portion made of synthetic resin is integrally molded on the outer periphery of an insert member having a concave groove in the axial direction to achieve both rigidity and accuracy. No measures have been taken to suppress the strain caused by the difference in shrinkage.

Patent Document 2 proposes a configuration in which a disk portion having an uneven portion is provided on a rotating shaft, and a gear is formed so as to cover the entire disk portion to improve the adhesion strength between the rotating shaft and the gear. However, no measures have been taken to suppress distortion due to the difference in shrinkage.

Further, Patent Document 3 has a configuration in which rigidity is ensured by engaging a convex portion provided on the side surface of the resin gear provided on the side surface of the resin gear with a hole portion provided on the side surface of the metal plate. Is proposing. Then, it is disclosed that cracking due to aging shrinkage is suppressed by setting a clearance between the convex portion and the engaging portion between the hole portion. However, the metal sheet metal for ensuring rigidity is only installed on one side of the flat surface of the resin material, and it is hard to say that it is firmly bonded in the thrust direction, and due to the clearance, the two are separated during use. there's a possibility that. As described above, in the prior art, when the gear is composed of two members made of different materials, it is difficult to secure the coupling force between the two members and suppress the crack caused by the shrinkage difference.

In view of the above problems, an object of the present invention is to provide a composite gear, a cartridge, an image forming apparatus, a molding die, and a method for manufacturing the composite gear, which can reduce the possibility of breakage such as cracking due to shrinkage over time.

One aspect of the present invention has a first member having a rotating shaft portion and a disk-shaped web extending in the radial direction from the rotating shaft portion, and having at least one or more meshing teeth on the outer circumference thereof. A composite gear including a second member supported by the first member and provided so as to surround the outer periphery of the first member, and the outermost outer peripheral surface of the first member is the second member. The innermost peripheral surface of the second member has a radial space between the first member and the first member, and the first member and the second member have a radial space between the two members. At least one is a composite gear formed so as to sandwich the first member and the other of the second member from both sides in the axial direction of the rotating shaft portion.

Another aspect of the present invention is a mold used for manufacturing a composite gear, wherein the composite gear has a rotating shaft portion and a disk-shaped web extending radially from the rotating shaft portion. The first member comprises a member and a second member having at least one or more meshing teeth on the outer periphery and being supported by the web and provided so as to surround the outer periphery of the first member. The outermost peripheral surface of the member has a radial space between the member and the second member, and the innermost peripheral surface of the second member has a radial space between the member and the first member. At least one of the first member and the second member is formed so as to sandwich the other of the first member and the second member from both sides in the axial direction of the rotating shaft portion. The molding die includes a first fixed mold, a second fixed mold, and a moving mold, and the first fixed mold is in a state of facing the first fixed mold. The member 1 is molded, and after the first member is molded, the moving mold is moved to a position facing the second fixed mold so as to be integrated with the first member. It is a molding die that is configured so that the second member is molded.

Yet another aspect of the present invention is a first step of forming a first member having a rotating shaft portion and a disk-shaped web extending radially from the rotating shaft portion, and a first step. The molded first member is housed in a molding die, and a second member having at least one meshing tooth on the outer periphery is formed so as to be supported by the web and surround the outer periphery of the first member. In the second step, the outermost peripheral surface of the first member has a radial space between the first member and the second member, and the second member has a space in the radial direction. The innermost peripheral surface has a radial space between the first member and the first member, and at least one of the first member and the second member is the other of the first member and the second member. Is a method for manufacturing a composite gear that forms the second member so as to sandwich the rotary shaft portion from both sides in the axial direction.

According to the present invention, the possibility of breakage such as cracking due to shrinkage over time can be reduced.

The composite gear according to the embodiment is shown, (a) is a perspective view of a first member constituting a rotating shaft portion, and (b) is an entire composite gear including a second member having meshing teeth on the outer periphery. It is a perspective view of. (A) to (c) are explanatory views which showed the structure of the composite gear which concerns on embodiment. (A) to (c) are explanatory views which showed the structure of the composite gear which concerns on embodiment. (A) and (b) are explanatory views which showed the structure and operation of the molding die which forms the composite gear which concerns on embodiment. (A) to (c) are explanatory views which showed the state after contraction of the composite gear which concerns on embodiment. (A) to (c) are explanatory views which showed the state after contraction of the composite gear which concerns on embodiment. (A) to (c) are explanatory views which showed the structure of the composite gear which concerns on Example 2. FIG. (A) to (c) are explanatory views which showed the structure of the composite gear which concerns on Example 3. (A) to (c) are explanatory views which showed the position of the gate mark of the composite gear which concerns on Example 4. FIG. (A) and (b) are explanatory views which showed the structure of the composite gear which concerns on Example 5. (A) to (c) are explanatory views which showed the structure of the composite gear which concerns on Example 6. (A) and (b) are explanatory views which showed the structure and operation of the molding die which forms the composite gear which concerns on Example 7. (A) and (b) are explanatory views showing the structure of the gear made of one kind of conventional synthetic resin. In the conventional gear, (a) is a perspective view of a first member constituting a rotating shaft portion, and (b) is a perspective view of the entire gear including a second member having meshing teeth on the outer periphery. (A) to (c) are explanatory views which showed the structure of the conventional compound gear. (A) is an explanatory diagram showing the stress distribution generated when the conventional composite gear is contracted, and (b) is an explanatory diagram showing the stress distribution generated when the composite gear according to the embodiment is contracted. It is explanatory drawing which showed the stress distribution generated when the composite gear which concerns on embodiment is rotationally driven. It is explanatory drawing which showed the structure of the image forming apparatus using the cartridge which concerns on embodiment. It is a perspective view which showed the structure of the cartridge which concerns on embodiment. (A) and (b) are explanatory views which showed the modification of the composite gear which concerns on embodiment. (A) to (c) are explanatory views which showed the modification of the composite gear which concerns on embodiment. (A) to (c) are explanatory views which showed the modification of the composite gear which concerns on embodiment. (A) to (g) are explanatory views which showed the modification of the composite gear which concerns on embodiment.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. The configuration shown below is merely an example. For example, a person skilled in the art can appropriately change the detailed configuration without departing from the spirit of the present invention. Moreover, the numerical value taken up in this embodiment is an example of possible numerical value setting.

1 (a) to 4 (b) show the configuration of the composite gear of the present embodiment and the molding die (mold) for molding the composite gear. Of these, FIGS. 1 (a) to 3 (c) show the configuration of the composite gear 10 of the present embodiment. FIG. 1A is shown in the form of a perspective view of a first member 50 constituting the rotating shaft portion of the composite gear 10 (FIG. 1B). FIG. 2B corresponds to a cross-sectional view taken along the line AA of FIG. 2A (top view of the composite gear 10), and is a cross-section parallel to the central axis of the rotation support portion 51 of the composite gear 10. Is shown. FIG. 2 (c) shows in detail the cross-sectional structure in the circle shown by the alternate long and short dash line in FIG. 2 (b). FIG. 3B corresponds to a cross-sectional view of line BB in FIG. 3A (side view of the composite gear 10), and FIG. 3C is shown by a single point chain line in FIG. 3B. The cross-sectional structure inside the circle is shown in detail.

Further, FIG. 19 shows the configuration of the image forming cartridge 1020 using the composite gear of the present embodiment, and FIG. 18 shows the configuration of the image forming apparatus 1010 using the cartridge 1020 of FIG. 19 by attaching and detaching the cartridge 1020. The composite gear of the present embodiment is used, for example, in the portion of the transmission member 100 (FIG. 19) of the cartridge 1020. The composite gear of the present embodiment is arranged so as to transmit the power of the image forming apparatus main body 1001 side to the mechanism in the cartridge 1020 via the drive shaft 1002. In the following, first, the configuration and operation of the image forming apparatus 1010 and the cartridge 1020 will be described with reference to FIGS. 18 and 19.

As shown in FIG. 18, the image forming apparatus 1010 is a full-color printer that employs an electrophotographic method. The image forming apparatus 1010 includes an image forming unit 1011 and a conveying unit 1012 for conveying the sheet S. The image forming unit 1011 as an image forming mechanism has a so-called tandem type structure in which a plurality of (four in this embodiment) cartridges 1020 are arranged in the traveling direction of the intermediate transfer belt 1027. Each cartridge 1020 is a process cartridge for an image forming apparatus that forms yellow, magenta, cyan, and black toner images, respectively.

A plurality of cartridges 1020 are detachably attached to the image forming apparatus main body 1001. Here, since the configuration of each cartridge 1020 is the same, the leftmost cartridge 1020 in FIG. 18 will be described below, and reference numerals and description will be omitted for other cartridges.

The cartridge 1020 includes a photosensitive drum 1021, a charging roller 1022, a developing device 1023, and a drum cleaner 1024. The photosensitive drum 1021 is rotationally driven at a predetermined process speed by a drum motor (not shown) arranged in the image forming apparatus main body 1001. The surface of the photosensitive drum 1021 is uniformly charged by the charging roller 1022. An electrostatic latent image is formed on the surface of the charged photosensitive drum 1021 by irradiating the surface of the charged photosensitive drum 1021 with a laser beam based on image information by the scanner unit 1025. The electrostatic latent image on the photosensitive drum 1021 is developed as a toner image by adhering toner to the developing device 1023. The toner image on the photosensitive drum 1021 is first transferred to the intermediate transfer belt 1027 by applying a primary transfer bias between the primary transfer roller 1026 and the photosensitive drum 1021. The transfer residual toner remaining on the photosensitive drum 1021 after the transfer is removed by the drum cleaner 1024.

By executing such a step on each cartridge 1020, the toner images of each color formed on the photosensitive drum 1021 of each cartridge 1020 are superimposed on the intermediate transfer belt 1027 and transferred onto the intermediate transfer belt 1027. A full-color toner image is formed. The toner image on the intermediate transfer belt 1027 is secondarily transferred to the sheet S conveyed by the transfer unit 1012 by the secondary transfer unit composed of the intermediate transfer belt 1027 and the secondary transfer roller 1028. The toner remaining on the intermediate transfer belt 1027 after transfer is removed by the belt cleaner 1029.

The transport unit 1012 is composed of a plurality of transport rollers, picks up the sheet S housed in the cassette 1013, and transports it to the secondary transfer unit of the image forming unit 1011. The sheet S is transferred to the secondary transfer unit by the registration roller pair 1014 in time with the toner image on the intermediate transfer belt 1027. The sheet S on which the toner image is transferred by the secondary transfer unit is heated and pressurized by the fixing device 1030 to fix the toner image. The sheet S on which the toner image is fixed is discharged to the discharge tray 1031.

FIG. 19 is a perspective view of the cartridge 1020 mounted on the image forming apparatus main body 1001 according to the first embodiment. The photosensitive drum 1021 has, for example, an aluminum cylindrical member extending in the longitudinal direction (± Z direction) and a photosensitive layer formed on the surface of the cylindrical member. A transmission member 100 to which the rotational force of a drum motor (not shown) of the image forming apparatus main body 1001 is transmitted is attached to the end portion of the photosensitive drum 1021 in the longitudinal direction. The transmission member 100 is configured so that the user attaches / detaches the cartridge 1020 to / from the image forming apparatus main body 1001 to engage or disengage the drive shaft 1002 on the image forming apparatus main body 1001 side. For example, when the cartridge 1020 is mounted on the image forming apparatus main body 1001, in FIG. 19, the user aligns the transmission member 100 and the drive shaft 1002 on the image forming apparatus main body 1001 side coaxially while moving the cartridge 1020 in the + Z direction. It is moved to engage the transmission member 100 with the drive shaft 1002. When removing the cartridge 1020 from the image forming apparatus main body 1001, in FIG. 19, the user moves the cartridge 1020 in the −Z direction to disengage the transmission member 100 from the drive shaft 1002.

Again, in FIGS. 1 (a) to 3 (c), the composite gear 10 of the present embodiment includes a first member 50 made of a highly rigid resin. The first member 50 constitutes a rotation shaft portion of the composite gear 10, and has a cylindrical rotation support portion 51. Further, the composite gear 10 includes a second member 30 made of a synthetic resin softer than the first member. The second member 30 covers the outer periphery of the first member 50 and has at least a tooth portion 31 (meshing tooth) on the outermost outer peripheral surface. In the present specification, the portion where the first member 50 and the second member 30 are in contact with each other is referred to as a connecting portion. Further, unless otherwise specified, with respect to the composite gear 10, the "rotational axis direction" represents the direction of the rotation axis of the rotation support portion 51. The "circumferential direction" represents the rotation direction centered on the rotation axis of the rotation support portion 51, and the "radial direction" and the "inner diameter direction inward-radial direction" represent the direction centered on the rotation axis of the rotation support portion 51. Represent.

As shown in FIGS. 1 (a) to 3 (c), the rotation support portion 51 of the first member 50 constitutes a rotation shaft portion, and has an inner diameter hole 52 and an outer diameter portion 53 (FIG. 2 (b)). , 54. A disk-shaped inner web 55 to be coupled to the second member 30 is arranged on the outer circumference of the rotation support portion 51.

The inner web 55 of the present embodiment is provided with a through hole 57 (FIGS. 2A and 2C). A plurality of through holes 57 are arranged on the circumference of the rotation support portion 51 at substantially the same distance from the center. In the present embodiment, the through hole 57 has a so-called fan surface shape, for example, as shown in FIGS. 3 (b) and 3 (c).

In the present embodiment, the two side edge portions 58, 58 that define the through hole 57 face each other in the circumferential direction and are oriented substantially parallel to the radial direction b1 (diameter direction) with respect to the center of rotation of the gear. Have. The second member 30 includes an outer web 32 that sandwiches the inner web 55 through the through hole 57 of the first member 50. Specifically, the outer web 32 has a first flange 32a, a penetrating portion 32b, and a second flange 32c. The first flange is a portion extending in the inner diameter direction from the annular rim 31r having the tooth portion 31 formed on the outer peripheral side toward the rotation axis of the rotation support portion 51. The penetrating portion 32b extends from the inner peripheral end of the first flange 32a in the direction of the rotation axis, penetrates the through hole 57, and is connected to the second flange 32c. The second flange 32c extends from the through portion 32b to the outer peripheral side of the outer peripheral edge portion 57b of the through hole 57. As described above, the outer web 32 of the second member 30 is formed so as to sandwich the outer peripheral edge portion 57b of the inner web 55 between the first flange 32a and the second flange 32c in the rotation axis direction. In other words, the first flange 32a and the second flange 32c provided on the second member 30 function as a holding portion that holds a part of the first member 50 from both sides in the axial direction.

The second member 30 is formed in a state of being integrated with the first member 50, for example, by performing two-color molding on the molded first member 50. At that time, the second member 30 is formed so as to penetrate the inner web 55 of the first member 50, leaving a space on the inner peripheral side of the through hole 57 with respect to the through hole 57, and to sandwich the inner web 55 from the front and back. Will be done. Further, when the second member 30 is formed, a space outside the outermost outer peripheral surface 55a of the inner web 55 of the first member 50 does not come into contact with the inner peripheral surface 31ra of the rim 31r of the second member 30. Two-color molding is performed so that

That is, in the present embodiment, as shown in FIG. 3C, the portion on the outer diameter side of the first member 50 and the portion on the inner diameter side of the second member 30 are brought into contact with each other at the above two locations. Instead, spaces a1 and a2 are formed. The space a1 is a space between the inner peripheral edge portion 57a of the through hole 57 of the first member 50 and the penetrating portion 31b of the second member 30 which are opposed to each other at a predetermined distance in the radial direction. .. The space a2 is a space between the outermost outer peripheral surface 55a of the first member 50 and the inner peripheral surface 31ra of the rim 31r of the second member 30, which face each other at a predetermined distance in the radial direction. .. The first member 50 is manufactured using a relatively high-rigidity synthetic resin material (first resin material) such as polyacetal, polybutylene terephthalate, polyphenylene sulfide, polyamide, and nylon. The second member 30 is manufactured by using a second resin material different from the first resin material, and a resin material having a relatively high slidability such as a polyacetal resin (copolymer) can be used.

4 (a) and 4 (b) show an example of a molding die forming the composite gear 10 in the present embodiment. The mold 1 is used to form the composite gear 10 by injection molding the first member 50 and the second member 30 by a method such as DSI (Die Slide Injection). In this example, the mold 1 is composed of a mold 2 on the fixed side (gate side) and a mold 3 on the movable side (anti-gate side) having the moving piece 4. After the first member 50 is molded, the moving piece 4 can be moved in the mold to a position where the second member 30 is molded together with the first member 50.

The moving piece 4 as a moving mold constitutes a first molding portion for molding the first member 50 together with the left half portion (first fixed mold) of the mold 2 on the fixed side, and the moving piece 4 is fixed. Together with the right half portion (second fixed mold) of the side mold 2, a second molding portion for molding the second member 30 is formed.

FIG. 4A shows a state in which the moving piece 4 is in the position of molding the first member 50 in the mold 1 and the first member 50 is molded. FIG. 4B is a diagram showing a state in which the moving piece 4 is moved to a position where the second member 30 is molded, and the second member 30 is molded at this position.

That is, this mold has a configuration in which a first molding portion for molding the first member and a second molding portion for molding the second member are arranged in a single mold. Then, the first molding portion installed on the movable side of the mold moves to a position facing the second molding portion together with the first member after molding the first member, and the first member and the second The second member is molded so as to be integrated with the member of.

Comparing the present embodiment as shown in FIGS. 1 (a) to 3 (c) with the conventional example shown in FIGS. 14 (a) to 15 (c), the inner web in the first member and the second The composition of the outer web on the member of is different. As described above, it is preferable that the first member and the second member of the composite gear are firmly connected, and the inner web and the outer web need to be connected by sandwiching.

Further, it is necessary to provide an anchor shape on the first member so as not to shift the phase in the rotation direction due to the driving torque of the gear to secure the joint strength with the second member. Although there is a big difference in the structure of the web between this embodiment and the conventional example, it is common that the inner web is sandwiched between the outer webs. Further, in the shape of the anchor, the uneven portion 67 plays the role in the conventional example, and the through hole 57 plays the role in the present embodiment.

However, in the composite gear 10 of the present embodiment, the outer diameter side of the first member 50 and the inner diameter side of the second member 30 are brought into contact with each other at the portion of the through hole 57 and the outermost portion of the first member 50. It is significantly different from the conventional example in that the space (a1, a2) is formed without forming. As described above, in the conventional configuration as shown in FIGS. 13 (a) to 15 (c), the composite is configured so that the first member is covered with the second member and does not have the space as described above. There was a concern that the gears would be distorted due to the difference in shrinkage over time and would be damaged. Alternatively, the wall thickness of the first member 50 and the second member 30 may be set so that the possibility of breakage is sufficiently small even in consideration of aging shrinkage, or the cost increase is allowed and damage does not occur. It was necessary to take measures such as setting.

On the other hand, in the present embodiment shown in FIGS. 1 (a) to 3 (c), spaces a1 and a2 are formed between the first member 50 and the second member 30, and the first member. 50 is less likely to inhibit the contraction of the second member 30, and the occurrence of strain is suppressed.

For example, FIGS. 5A to 6C show a state in which the second member 30 is contracted in the composite gear 10 of the present embodiment. Since the second member 30 is a circular molded product, shrinkage in the inner diameter direction occurs toward the center of the circle. Therefore, the spaces a1 and a2 that existed before the contraction are reduced to the smaller spaces a3 and a4, and a new space a5 is formed. That is, with the contraction of the second member 30, the radial distance between the inner peripheral edge portion 57a of the through hole 57 of the inner web 55 and the through portion 32b of the outer web 32, and the maximum of the first member 50. The distance between the outer peripheral surface 55a and the inner peripheral surface 31ra of the rim 31r of the second member 30 is shortened. On the other hand, a gap (space a5) is formed in the radial direction between the outer peripheral edge portion 57b of the through hole 57 of the inner web 55 and the through portion 32b of the outer web 32. As described above, the spaces a1 to a5 between the first member 50 and the second member 30 are formed with the inner web 55 in the radial direction caused by the difference in the shrinkage ratio between the first member 50 and the second member 30. It functions as a receiver for absorbing the relative position change of the outer web 32. By the action of this receiving allowance, the occurrence of distortion of the composite gear can be suppressed.

Further, the through hole 57 of the first member 50 of the composite gear 10 of the present embodiment includes two side edge portions 58, 58 in the same direction as the radial direction b1. As described above, the second member 30 contracts in the circumferential direction at almost the same ratio as the contraction in the radial direction. Therefore, the second member 30 contracts in contact with the side edges 58, 58 of the through hole 57 of the first member 50. Due to this action, even if the second member 30 contracts, there is no gap between the first member 50 and the second member 30 of the gear in the circumferential direction, and the two members are tightly coupled. The state is maintained. Further, since the contraction of the second member 30 occurs along the side edge portions 58, 58 of the through hole 57 having a direction substantially coincide with the radial direction, it is possible to reduce the occurrence of distortion in the circumferential direction of the gear.

As described above, even after the relative positional changes between the inner web 55 and the outer web 32 occur, the inner web 55 is sandwiched between the outer web 32 in the radial direction, and the outer web 32 is formed through the through hole 57. The state of being engaged with the inner web 55 is maintained. That is, the above spaces a1 to a5 do not affect the coupling of the first member 50 and the second member 30 so as to be relatively immovable in the axial direction and the circumferential direction, and the first member is due to the difference in shrinkage rate. It is possible to suppress the occurrence of strain by allowing dimensional changes of the member 50 and the second member 30. In other words, the composite gear of the present embodiment can firmly bond the first member 50 and the second member 30 and suppress breakage such as cracking due to shrinkage over time. Hereinafter, the configuration in which the details of the composite gear of the present embodiment are modified will be described with reference to FIGS. 7 (a) to 12 (b).

7 (a) to 12 (b) show a modified configuration of the details of the composite gear of the present embodiment. In the following, the same components as those of the composite gear 10 and the mold 1 shown in FIGS. 1 (a) to 4 (b) are designated by the same reference numerals, and duplicate description will be omitted.

In the configuration shown in FIG. 3C, the side edge portions 58, 58 of the through hole 57 coincide with the radial direction b1 centered on the rotation axis. On the other hand, in the composite gear 11 shown in FIGS. 7A to 7C, the side edge portion b2 and the side edge portion b3 of the through hole 57 have an inclined angle with respect to the radial direction b1. FIG. 7A shows a cross section of the composite gear 11 at the same position as the composite gear 10 of FIG. 3B. FIG. 7 (b) shows an example in which the side edge portions b2 and b2 are formed at an angle smaller than the radial direction b1, and FIG. 7 (c) shows an example in which the side edge portions b3 and b3 are formed at an angle larger than the radial direction b1. Is shown. However, the magnitude of the inclination angle of the side edge portion is determined by the angle φ1 formed by the line extending the ridgeline of the two side edge portions with the central angle φ0 (FIG. 7 (a)) of the through hole 57 as a reference (0 °). It is expressed by whether φ2 is large or small. When the inclination angle of the side edge portion is negative, as shown in FIG. 7B, the reduction rate of the distance between the side edge portions b2 and b2 in the circumferential direction when heading in the inner diameter direction is such that the side edge portion is radiated in the radial direction b1. The configuration is smaller than when formed along b1 (side edges b2 and b2 are closer to parallel). Further, when the inclination angle of the side edge portion is positive, as shown in FIG. 7 (c), the reduction rate of the distance between the side edge portions b3 and b3 in the circumferential direction when heading toward the inner diameter direction radiates from the side edge portion. The configuration is larger than that when formed along b1 and b1. In other words, when the inclination angle of the side edge portion is positive, the intersection of the extension lines of the side edge portion is closer to the through hole 57 than the rotation axis of the composite gear 10.

According to the composite gear 11 having such a configuration, it is possible to suppress the strain and maintain the coupling force even if the contraction of the second member 30 is anisotropic. For example, if the contraction rate in the radial direction is larger than the contraction rate in the circumferential direction of the second member 30, in the configuration shown in FIGS. 3A to 3C, the through hole 57 of the first member 50 The two side edges 58 may act as resistance to contraction of the second member 30 and cause tensile stress. With respect to the anisotropy of shrinkage of the second member 30, as shown in FIG. 7B, the intersection angle φ1 of the two side edge portions b2 and b2 of the through hole 57 is reduced to make the second member 30 second. The contraction of the member 30 is less likely to be hindered, and the occurrence of distortion of the composite gear 11 can be reduced.

Further, when the contraction rate in the circumferential direction is larger than the contraction rate in the radial direction of the second member 30, a gap is generated between the first and second members in the circumferential direction. In this case, play may occur between the first member 50 and the second member 30. With respect to the anisotropy of shrinkage of the second member 30, by increasing the intersection angle φ2 of the two side edge portions b3 and b3 of the through hole as shown in FIG. 7C, the second member 30 is second. Even if the members of No. 1 are contracted, no gap is formed and the connection between the first member 50 and the second member 30 is maintained tightly.

As is clear from the above example, the intersection angle of the two side edges of the through hole of the first member 50 may be determined according to the contraction rate of the second member 30, for example, its anisotropy. .. In that case, the angle of the linear side edge portion can be selected to be, for example, an inclination angle in the range of −10 ° to +10 ° with respect to the diameter direction (radiation direction) of the rotation shaft portion.

8 (a) to 8 (c) show different configurations of the composite gear 12. Here, FIG. 8A is a front view of the composite gear 12, FIG. 8B is a sectional view, and FIG. 8C is a detailed view. This example is a configuration in which the shrinkage of the second member 30 in the wall thickness direction is taken into consideration. That is, the shrinkage of the second member 30 made of polyacetal resin or the like occurs slightly not only in the inner diameter direction and the circumferential direction but also in the wall thickness direction. Since the shrinkage in the wall thickness direction is very small compared to the outer diameter and the circumference, the strain generated is small and the possibility of the molded product cracking is low. However, in the present embodiment, since the first member 50 is sandwiched by the second member 30, even a slight contraction in the thickness direction may hinder the contraction of the second member in the inner diameter direction. There is. Therefore, as shown in FIGS. 8 (b) and 8 (c), the composite gear 12 is provided with a gradient c such that the inner web 55 of the first member 50 is thinned inward, that is, the thickness is gradually reduced. ing. With the configuration in which the inner web 55 of the first member 50 is provided with the thickness gradient c in this way, even if the second member 30 contracts in the wall thickness direction, the contraction in the inner diameter direction is less likely to be hindered. It becomes easier to obtain the action. In other words, due to the contraction of the penetrating portion 32b of the outer web 32 and the like, the first flange 32a and the second flange 32c holding the inner web 55 tend to approach each other in the axial direction. At this time, the gradient c of the inner web 55 causes the outer web 32 to receive a reaction force in the inner diameter direction from the inner web 55, so that the second member 30 tends to contract uniformly in the inner diameter direction. It is assumed that the gradient c is set in at least a portion of the inner web 55 sandwiched by the second member 30.

9 (a) to 9 (c) show different configurations of the composite gear 13. Here, FIG. 9A is a front view of the composite gear 13, FIG. 9B is a rear view, and FIG. 9C is a sectional view. The composite gear 13 has a gate mark 33 when the second member 30 is ejected at a position on the through hole 57 of the first member 50 (four points represented by black dots in the illustrated example) in the axial direction. Have. When there are a plurality of gates, at least a part (preferably all) of the gate marks 33 may be on the through hole 57. Further, for each gate, at least a part (preferably all) of the area of the gate mark 33 may overlap with the through hole 57 in the axial direction. By arranging the gate when the second member 30 is insert-molded at the position indicated by the gate mark 33, the pressure generated when the second member 30 is injection-molded is applied to the gate through the through hole. You can escape to the other side. This has the advantage that the first member 50 is less likely to be deformed.

10 (a) and 10 (b) show different configurations of the composite gear 14. Here, FIG. 10A is a front view of the composite gear 14, and FIG. 10B is a detailed view of the vicinity of the through hole 57. The composite gear 14 has a curved shape such as a chamfered or cylindrical surface at a corner R (corner part) of a through hole 57 of the first member 50. The through hole 57 has a fan surface shape defined by two side edge portions 58 and 58, and an outer peripheral edge portion 57b and an inner peripheral edge portion 57a connecting them as described above. That is, the side edge portions 58, 58 and the outer peripheral edge portion 57b and / or the inner peripheral edge portion 57a are chamfered or made continuous via a corner portion R having a curved shape such as a cylindrical surface.

In particular, as shown in FIGS. 10A and 10B, a chamfered or cylindrical surface can be provided at the corner R between the inner peripheral edge portion 57a and the side edge portions 58 and 58. In this way, in the configuration in which the corner R between the inner peripheral edge portion 57a and the side edge portions 58, 58 is not provided with a chamfer or a cylindrical surface and is formed as a sharp edged corner, the corner portion is formed by the driving torque of the gear. Causes stress concentration called the notch effect. This stress acts to tear the corners of the corner. However, with such a configuration as described above, the stress on the corners can be dispersed and the mechanical strength of the composite gear 14 can be increased.

11 (a) to 11 (c) and 12 (a) and 12 (b) show a composite gear 15 having a further different configuration, and a mold 1 as a molding die used for manufacturing the composite gear 15. Shown. Here, FIG. 11A is a front view of the composite gear 15, FIG. 11B is a sectional view, and FIG. 11C is a detailed view. FIG. 12A is a cross-sectional view of the mold 1, and the configuration of the mold 1 is the same as that shown in FIG. Further, FIG. 12B shows a state when the second member 30 is molded. In the composite gear 15 of FIGS. 11A to 11C, a ring-shaped ridge d is provided on the outermost peripheral portion of the inner web 55 of the molded first member 50. In such a configuration, when the second member 30 is molded in two colors with respect to the molded first member 50, the ridge d of the first member 50 and the mold piece 5 are brought into contact with each other. It is possible to prevent the resin material for the second member 30 from being filled between the second member 30 and the first member 50. That is, a space can be formed between the outermost circumference of the first member 50 and the inner circumference of the second member 30 so that they do not come into contact with each other and absorb the contraction of the second member 30. Therefore, the composite gear having the structure of the present embodiment can be easily and surely manufactured.

Further, FIG. 20 (a, b) shows a further different configuration. In this configuration, the central angle φ of each through hole 57 formed in the inner web 55 with respect to the rotation center of the first member 50 is different from the configuration shown in FIGS. 3 (a to 3). In other words, in the configuration of FIGS. 20 (a, b) and 3 (a to 3), the resin is filled as a part of the inner web 55 and the region where the through hole 57 is formed in the circumferential direction. The ratio with the area is different. By controlling the central angle φ of the through hole 57 of the first member 50 as shown in this figure, the pressure generated when the second member 30 is formed can be adjusted, and at the same time, the inner web of the first member 50 can be adjusted. The rigidity of 55 can be adjusted. As a result, it is possible to obtain an effect of suppressing the deformation of the inner web 55 of the first member 50 due to the molding of the second member 30 while maintaining the effect of suppressing the generation of strain due to the contraction of the second member 30. it can.

In view of the above, the angle (central angle φ) formed by the lines extending the ridges of the two side edges of the through hole 57 is preferably in the following range, for example.
However, l [mm] is the length from the outermost peripheral surface of the first member 50 to the outer peripheral edge portion 57b of the through hole 57, and t [mm] is the thickness of the inner web 55 of the first member 50 (through hole 57). The thickness in the vicinity of) is shown. Also,

In each of the above-mentioned configuration examples in the present embodiment, as shown in FIGS. 1A to 3C, an example in which the through hole 57 is provided in the first member 50 is shown. However, it is not limited to this. 21 (a to c), 22 (a to c), and 23 (a to e) show a modified configuration of the details of the composite gear of the present embodiment. In the following, the same components as those of the composite gear 10 shown in FIGS. 1 (a) to 3 (c) will be designated by the same reference numerals, and redundant description will be omitted.

21 (a) shows a front view of one modification, FIG. 21 (b) shows a cross-sectional view of the composite gear shown in (a) in the EE portion, and FIG. 21 (c) shows a detailed view thereof. As shown here, the second member 30 may be provided with a through hole 57. In this case, the inner web 55 of the first member 50 is opposite to the first flange 55c extending in the radial direction, the penetrating portion 55d extending in the axial direction and passing through the through hole 57, and the first flange 55c of the outer web 32. A second flange 55e that extends radially on the side is provided. As a result, the first member 50 and the second member 30 are joined in a state where the outer web 32 is sandwiched from both sides in the axial direction by the first flange 55c and the second flange 55e. In other words, the first flange 55c and the second flange 55e provided on the first member 50 function as a holding portion that holds a part of the second member 30 from both sides in the axial direction. That is, in this modification, a part of the first member 50 sandwiches a part of the second member 30 from both sides in the radial direction.

In this modification, a radial space a6 is provided between the outer peripheral edge portion 57b of the through hole 57 and the outer peripheral side surface of the through portion 55b. Further, a radial space a7 is also provided between the outermost peripheral surface of the inner web 55 and the rim 31r of the second member 30. These spaces a6 and a7 are the first spaces a6 and a7, similarly to the spaces a1 and a2 in the configurations of FIGS. 1 (a) to 3 (c), while maintaining the bonding strength between the first member and the second member. It functions as a receiving allowance for absorbing the relative position change caused by the difference in shrinkage between the member and the second member.

In this modification, when the two colors are formed, the first member 50 can be formed after the second member 30 is formed. According to the configuration of this modification, when the material of the second member 30 has a higher melting point than the material of the first member 50, it is better to provide the through hole 57 in the second member 30 for the performance of the gear. Can be enhanced.

22 (a) shows a front view of another modified example, FIG. 22 (b) shows a cross-sectional view of the FF portion of the composite gear shown in (a), and FIG. 22 (c) is a detailed view thereof. As described above, the squared-C shape engaging shape 50A in which the cross section provided on the first member 50 opens inward in the radial direction and the cross section provided on the second member 30 are in the radial direction. It may be combined with a U-shaped engaging shape 30A that opens outward. That is, in this modification, a part (50A) of the first member 50 functions as a first holding portion for holding a part of the second member 30 from both sides in the axial direction, and at the same time, the second member 30. A part (30A) functions as a second holding portion that holds a part of the first member 50 from both sides in the axial direction. Further, this modification is an example of a configuration in which one of the first member and the second member sandwiches the other without passing through a through hole provided in the first member or the second member.

In this modification, the inner peripheral surface of the engaging shape 30A, which is the innermost peripheral surface of the second member 30, and the surface of the first member 50 facing the engaging shape 30A in the radial direction (rotational support portion 51). A space a9 is provided between the outer diameter portion 54). Further, a space a8 is provided between the outermost peripheral surface of the engaging shape 50A of the first member 50 and the rim 31r of the second member 30 facing the engaging shape 50A in the radial direction. These spaces a8 and a9 are the first, as in the spaces a1 and a2 in the configurations of FIGS. 1 (a) to 3 (c), while maintaining the bonding strength between the first member and the second member. It functions as a receiving allowance for absorbing the relative position change caused by the difference in shrinkage between the member and the second member. As a result, the thickness of the molded product may be increased, but the processing of the mold for manufacturing the molded product can be simplified.

Further, FIG. 23A is a perspective view of the first member 50 of another modified example, and FIG. 23B is a perspective view of the composite gear 10 including the second member 30. (C) shows the front view of the composite gear 10, and (d) and (f) show the cross-sectional view of the FF portion and the GG portion of the composite gear 10, respectively. Further, (e) and (g) show detailed views of (d) and (f), respectively.

The inner web 55 of the first member 50 of this modification has a plurality of concave portions 55u and a plurality of convex portions 55p on the outer periphery. On the other hand, the second member 30 is formed so that the first flange 32a and the second flange 32c of the outer web 32 sandwich the convex portions 55p of the inner web 55 from both sides in the radial direction.

In this modification, the inner peripheral surface of the outer web 32, which is the innermost peripheral surface of the second member 30, and the surface of the first member 50 facing the outer web 32 in the radial direction (outer diameter of the rotation support portion 51). A space a10 is provided between the part 54) and the space a10. Further, a space a11 is provided between the outer peripheral surface of the convex portion 55p, which is the outermost outer peripheral surface of the first member 50, and the rim 31r of the second member 30 facing the convex portion 55p in the radial direction. Further, between the outer peripheral surface of the recess 55u and the surface of the second member 30 facing the recess 55u in the radial direction (the surface connecting the first flange 32a and the second flange 32c and extending in the axial direction). Space a12 is provided. These spaces a10 to a12 are the first, as in the spaces a1 and a2 in the configurations of FIGS. 1 (a) to 3 (c), while maintaining the bonding strength between the first member and the second member. It functions as a receiver that absorbs the relative position change caused by the difference in shrinkage between the member and the second member.

This modification is another example of a configuration in which one of the first member and the second member sandwiches the other without passing through a through hole provided in the first member or the second member. As a result, it is possible to simplify the processing of the mold for manufacturing the composite gear 10 which is a molded product. 23 (a) to 23 (g) show an example in which the first member 50 is provided with the concave portion 55u and the convex portion 55p, but the second member 30 has the concave portion and the convex portion on the inner circumference. The first member 50 may be formed so as to sandwich the convex portion. This makes it possible to simplify the processing of the mold for manufacturing the molded product.

In the following, as Examples 1 to 7, the configurations shown in FIGS. 1 (a) to 6 (c), and FIGS. 7 (a) to 12 (b) and FIGS. 20 (a) to 23 (g) The evaluation results regarding the performance or characteristics of the composite gear having the configuration of the modified example shown in the above will be described.

<Example 1>
Below, in the gear of Example 1 and the composite gear of Comparative Examples 1 and 2, the endurance time when there is a large difference in the shrinkage ratio between the first member 50 and the second member 30 is evaluated. The configuration of the first embodiment is the composite gear shown in FIGS. 1 (a) to 3 (c). Polybutadiene terephthalate resin (containing 30% of glass fiber) is used for the first member 50, and polyacetal resin (copolymer) is used for the second member 30. The tooth portion 31 (meshing tooth) of the second member 30 is formed with a module m = 0.5, a pressure angle of 20 °, a number of teeth of 91, a twist angle β = 20 °, and a tooth width t = 10 mm. For the composite gear, the first member was formed and then the second member was formed using a mold as shown in FIG.

Table 1 below shows the results of measuring the elapsed time until cracks occur after putting and storing the gears of Comparative Examples 1 and 2 and Example 1 in the 80 ° C and 120 ° C high temperature furnaces. In addition, rotation transmission error (transmission error of one tooth component when driving at a rotation speed of 25 rpm with a torque of 0.1 Nm) was measured.

Comparative Example 1 is an example of a conventional resin gear as shown in FIGS. 13 (a and 13), and is made of only polyacetal (POM) resin. Comparative Example 2 is a composite gear having the configurations described in FIGS. 14 (a) to 15 (c), and the first member and the second member are formed with the same material configuration as that of the first embodiment.

As shown in Table 1, when Comparative Example 1 and Comparative Example 2 having the conventional configuration and Example 1 were compared, a large difference was observed in the rotation transmission error, and the error of Comparative Example 1 was large. This is because the gear of Comparative Example 1 uses the same material for both the rotary support part and the gear part, and because polyacetal, which has relatively weak rigidity, is used, the gear is deformed by the torque during rotational drive. Conceivable. On the other hand, since Comparative Example 2 and Example 1 are made of a composite material, the component rigidity is strong and the rotation transmission error is good.

However, it was confirmed that Comparative Example 1 was longer and more advantageous than Comparative Example 2 and Example 1 in terms of endurance time in a high temperature environment. It is considered that this is because Comparative Example 1 is made of only the same material, so that distortion due to the difference in shrinkage does not occur. Nevertheless, in Comparative Example 1, cracks were generated in 13230 hours in the 80 ° C environment and 1825 hours in the 120 ° C environment. It is considered that this is not due to breakage due to strain, but due to a decrease in mechanical strength due to elongation, cutting and condensation of the material molecular chain due to aging in a high temperature environment. On the other hand, the durability time of Comparative Example 2 which does not have a structure for absorbing the contraction of the second member 30 is extremely short. It is considered that this is because the strain is generated due to the shrinkage difference of the composite material between the second member and the first member constituting the composite gear. On the other hand, although Example 1 is also formed of a composite material, although it is inferior to Comparative Example 1, almost the same durability time is obtained. This is because, in the first embodiment, since the inner peripheral side of the through hole 57 and the outer peripheral side of the first member 50 have a space for absorbing the contraction of the second member 30, the occurrence of distortion is minimized. It can be inferred that it is suppressed to.

In FIGS. 16A and 16B, 0.13% of the first member constituting the rotating shaft portion and the second member on the outer peripheral side are 0.13% of the two composite gears of Comparative Example 2 and Example 1. It is an analysis result of the stress generated in the second member when it is assumed that the shrinkage of 0.36% occurs. FIG. 16 (a) corresponds to the analysis results of Comparative Example 2 and FIG. 16 (b), and the portion having a large stress is represented by a light color and the portion having a small stress is represented by a dark color. As is clear from comparing FIGS. 16A and 16B, it can be seen that a large stress is generated in Comparative Example 2 of FIG. 16A. The portion where the stress is most generated corresponds to the uneven portion 67 (FIG. 14A) of the first member. That is, it is shown that the shape of the uneven portion 67 provided as an anchor in the rotation direction causes stress due to the contraction action. On the other hand, according to the first embodiment, it can be seen that stress does not occur even if the second member contracts because the space for absorbing the contraction is provided.

<Example 2>
In the following, the composite gear of Example 1, the composite gear of FIG. 7 (b) (Example 2-1), the composite gear of FIG. 7 (c) (Example 2-2), and the conventional composite gear (Comparative Example 2). : The same as in Comparative Example 2 above) is shown. The materials and gear specifications of each part of Examples 2-1 and 2-2 are the same as those of the above-mentioned Example 1, but the side edges of the through holes are gears as shown in FIGS. 7 (b) and 7 (c). The difference is that it is tilted from the radial direction of the center. In Example 2-1, the side edge of the through hole is radiated by -10 ° (FIG. 7 (b)), and in Example 2-2, the side edge of the through hole is radiated by + 10 ° (FIG. 7 (c)). The structure is inclined from the (diameter) direction. The side edge of the through hole of the first embodiment has a structure extending along the radial direction of the center of the gear.

Table 2 below shows the results of evaluating the elapsed time until cracks occur after putting and storing the composite gears of Comparative Example 2 and Examples 1, 2-1 and 2-2 in the 80 ° C and 120 ° C high temperature furnaces. Is. In addition, the rotation transmission error (torque 0.1 Nm, transmission error of one tooth component when driven at a rotation speed of 25 rpm) after storage in a normal temperature and humidity environment (23 ° C-50%) for one year was also measured. There is.

As shown in Table 2, when Comparative Example 2 and Examples 2-1 and 2-2 having the conventional configuration are compared, it can be seen that the durability time is remarkably improved in Examples 2-1 and 2-2. In particular, Example 2-1 is superior in durability time as compared with Example 1. However, in particular, the rotation transmission error of Example 2-1 one year later is slightly worse than that of Example 1. On the other hand, it was confirmed that the endurance time of Example 2-2 was also improved, but the endurance time was slightly shorter than that of Example 1 (80 ° C). However, the rotation error of Example 2-2 after one year is better than that of Example 1, and the accuracy is high. From these results, it is considered that in Example 1 (the side edge portion of the through hole is along the radial direction about the rotation axis), the contraction of the second member is anisotropic. For example, if the shrinkage rate in the inner diameter direction is smaller than the shrinkage rate in the circumferential direction, a gap is generated between the first and second members in the circumferential direction. In such a state, distortion is less likely to occur, but the rotation transmission error is exacerbated by the influence of the gap. Then, in Example 2-1 because the inclination of the side edge portion is set to -10 °, which is negative, it is considered that a larger gap is generated and the durability time is improved, but the rotation transmission error is deteriorated. .. On the other hand, in Example 2-2, since the inclination of the side edge is set to + 10 °, some distortion is generated instead of no gap, so that the durability time is slightly reduced and the rotation transmission error is good. It is thought that it has become.

From the above evaluation results, it can be seen that the inclination angle of the side edge portion of the through hole can be selected depending on whether the shrinkage rate of the second member, the rotation transmission error, or the durability is prioritized. For example, it is preferable that the composite gear can be appropriately selected because it depends on the application whether the rotation transmission error is prioritized or the durability is prioritized. For example, when the shrinkage rate in the inner diameter direction is smaller than the shrinkage rate in the circumferential direction, the inclination of the side edge is negative to obtain rotational transmission accuracy, and the inclination of the side edge is positive to obtain durability. It is possible to set it to. When the shrinkage rate in the inner diameter direction is larger than the shrinkage rate in the circumferential direction, the inclination of the side edge portion is positive in order to obtain rotational transmission accuracy, and the inclination of the side edge portion is negative in order to obtain durability. It is possible to set it to.

<Example 3>
Hereinafter, the evaluation of the composite gear of the third embodiment (FIGS. 8 (a to c)) and the composite gear of the comparative example 2 (FIGS. 14 (a, b)) will be described. The material of each part of the third embodiment and the gear specifications are the same as those of the first embodiment, but the composite gear of the third embodiment has the inner web of the first member as shown in FIGS. 8 (a to c). Is sloped inward by 0.5 ° so that the thickness gradually decreases (thinning). Table 3 below shows the results of investigating the elapsed time until cracks occur after putting and storing the composite gears of Comparative Example 2 and Examples 1 and 3 in the 80 ° C and 120 ° C high temperature furnaces.

As shown in Table 3, when Comparative Example 2 having the conventional configuration is compared with Example 1 and Example 3, it can be seen that the durability time of Example 3 is remarkably improved. That is, even if the second member 30 contracts in the wall thickness direction, the inner web of the first member 50 is reduced in thickness by that amount, so that the contraction in the inner diameter direction is less likely to be hindered and distortion occurs. Is suppressed.

<Example 4>
Hereinafter, the evaluation of the composite gears (Examples 1 and 4) having the configuration shown in FIGS. 9 (a to 4) and the conventional composite gears (Comparative Example 2 above) will be described. Table 4 below shows the rotation transmission error (torque 0.1 N.) Of the composite gear having the configuration shown in FIGS. 9 (a to c) (Examples 1 and 4) and the conventional composite gear (Comparative Example 2 above). The comparison result (m, transmission error of one tooth component when driven at a rotation speed of 25 rpm) is shown. The material, gear specifications, and web shape of each part of the fourth embodiment are the same as those of the first embodiment, but in the fourth embodiment, as shown in FIG. 9, the gate for injecting the second member is the first member. It is arranged at a position on the through hole.

Comparing Comparative Example 2 and Examples 1 and 4 having the conventional configuration, the rotation transmission error is greatly improved in Example 4. It is considered that this is a result of the injection gate of the second member being arranged on the through hole of the first member, so that the first member is less likely to receive the pressure associated with injection molding and is less likely to be deformed. ..

<Example 5>
Hereinafter, evaluation of the composite gear having the configuration shown in FIGS. 10 (a and b) (Example 5), the above-mentioned Example 1, and the conventional composite gear (the above-mentioned Comparative Example 2) will be described.

Table 5 shows the comparison results of the composite gear of Example 5 having the configuration of FIGS. 10 (a, b), the above-mentioned Example 1, and the conventional composite gear (the above-mentioned Comparative Example 2). The material of each part of the fifth embodiment and the gear specifications are the same as those of the first embodiment, but as shown in FIGS. 10A and 10B, the corner portion of the through hole of the first member, particularly the inner peripheral side. The corners of the are curved (cylindrical surface, chamfered). Table 5 shows the analysis of the maximum principal stress (MPa) generated in the first member when the CAD models of the composite gears of Comparative Examples 2 and 1 and 5 are rotationally driven with a torque of 0.1 Nm. Corresponds to the result.

Comparing Comparative Example 2 having the conventional configuration with Examples 1 and 5, the principal stress of Example 1 is larger than that of Comparative Example 2, but the principal stress of Example 5 is smaller than that of Comparative Example 2. There is. Here, FIG. 17 is the analysis result of the first embodiment and shows the stress distribution generated in the first member when the torque is applied counterclockwise to the composite gear. As shown in FIG. 17, it can be seen that a large amount of stress is generated at the corner of the through hole. This is a so-called notch effect, and stress tends to be easily concentrated on a portion such as a corner of the through hole of the first embodiment. However, as shown in Table 5, only by adding a curved shape, for example, a cylindrical surface or a chamfered shape to the corner of the through hole where stress is likely to be concentrated as shown in Example 5, that is, FIGS. 10 (a, b). It has the effect of dispersing stress and reducing principal stress.

<Example 6>
In the following, the evaluation of the composite gear of Example 6 configured as shown in FIGS. 11 (a to 11) and the composite gear of Example 1 and Comparative Example 2 described above will be described. In the composite gear of the sixth embodiment, the material of each part and the gear specifications are the same as those of the first embodiment, but as shown in FIGS. 11 (a to c), the outer peripheral portion of the inner web 55 of the first member 50. A ring-shaped ridge d is provided on the surface.

Table 6 shows the comparison results of the composite gear of Example 6 having the configuration of FIGS. 11 (a to c), the above-mentioned Example 1, and the conventional composite gear (the above-mentioned Comparative Example 2). The evaluation is the endurance time (hr), and this endurance time (hr) is the elapsed time from putting and storing the composite gears of Comparative Example 2 and Examples 1 and 6 in the high temperature furnaces at 80 ° C and 120 ° C until cracks occur. Corresponds to time.

Comparing Comparative Example 2 and Examples 1 and 6 having the conventional configuration, the durability time is particularly improved in Example 6. It is considered that this is a result of making it difficult for the second member to be formed on the outer diameter of the first member by providing the ridge d in a ring shape on the outer periphery of the inner web of the first member of the sixth embodiment. Good. In this example, a polyacetal resin is used for the second member, but in normal injection molding, the resin tends to flow in if there is a space of about 10 μm. The first embodiment lacks the ridges as in the sixth embodiment, and the first member itself contracts from the formation of the first member to the formation of the second member, and the mold and the first member are formed. There is a possibility that some gaps have been formed between the members of. In such a case, a minute material of the second member flows into the outer peripheral portion of the first member. When the second member is formed on the outer peripheral portion of the first member, the space for absorbing the contraction of the second member is reduced, the contraction of the second member is hindered, and the durability time for breakage such as cracking is reduced. descend. However, in the sixth embodiment, the ridge d (FIGS. 11 (a to c)) exerts an action of damming the inflow, a space for absorbing the contraction of the second member can be secured, and the damage such as cracking is prevented. It becomes possible to improve the durability time.

<Example 7>
Hereinafter, the evaluation of the composite gear (Example 7) configured as shown in FIGS. 20 (a, b) and the composite gear of the above-described first embodiment will be described. In the composite gear of Example 7 (a, b), the material of each part and the gear specification are the same as those of Example 1 above, but as shown in FIG. 20 (a, b), the through hole on the inner web The angle φ formed by the side edge portion is made larger than that in the first embodiment. In other words, the ratio of the regions where the through holes are provided in the circumferential direction is larger than that of the first embodiment.

Table 7 shows the comparison results of the composite gear of Example 7 having the configuration of FIGS. 20 (a, b) and the composite gear of Example 1 described above. The evaluation is the deformation of the inner web of the first member by the molding of the second member, and corresponds to the analysis result (μm) of the amount of deformation at the time of completion of filling.

Comparing Example 1 and Example 7, the deformation of the inner web is suppressed in Example 7. This is a result of alleviating the pressure generated when the second member is formed by increasing the angle formed by the side edge portion. It is considered that the rigidity of the web is reduced, but it can be said that the effect of pressure relaxation is more effective than the effect of the decrease in rigidity.

1 ... Molding mold (die), 2 ... 1st fixed mold, 2nd fixed mold (die), 4 ... Moving piece (moving mold), 10-15, 40 ... Composite gear, 30, 90 ... 2nd member, 31 ... tooth part, 32, 92 ... outer web, 50, 60, 74 ... first member, 51, 61 ... rotary support part, 55, 65 ... inner web, 57 ... through hole, 57a ... Inner peripheral edge, 57b ... Outer peripheral edge, 58 ... Side edge.

Claims (18)

A first member having a rotating shaft portion and a disk-shaped web extending radially from the rotating shaft portion,
A composite gear having at least one meshing tooth on the outer circumference and a second member supported by the web and provided so as to surround the outer circumference of the first member.
The outermost outer peripheral surface of the first member has a radial space between the first member and the second member, and the innermost peripheral surface of the second member has a radial space between the first member and the first member. The first member and at least one of the second members are formed so as to sandwich the other of the first member and the second member from both sides in the axial direction of the rotating shaft portion. Is a composite gear. The composite gear according to claim 1, wherein the second member has a holding portion that holds a part of the first member from both sides in the axial direction. The composite gear according to claim 2, wherein the portion of the web sandwiched by the sandwiching portion is formed so that the thickness in the axial direction gradually decreases as the portion sandwiched by the sandwiching portion of the web is directed from the outer circumference toward the rotating shaft portion. The web of the first member is provided with a through hole penetrating in the axial direction.
The second member is formed so as to penetrate the through hole.
The first member is made of a first resin material, the second member is made of a second resin material, and the first resin material has higher rigidity than the second resin material.
The gate mark of the gate on which the second resin material is injected into the first member, which has been molded so as to integrate the first member and the second member, is formed on the first member. The composite gear according to claim 1, which is provided at a position of a through hole. The composite gear according to claim 1, wherein a ridge is formed on the outer periphery of the web of the first member. The first member and the other of the second member are provided with through holes including two side edges facing each other in the circumferential direction of the rotating shaft portion.
The composite gear according to claim 1, wherein the first member and one of the second members are formed so as to penetrate the through hole. The sixth aspect of claim 6, wherein each of the side edge portions extends linearly when viewed in the axial direction, and has an inclination angle in the range of −10 ° to +10 ° with respect to the radial direction of the rotating shaft portion. Composite gear. The through hole is provided in the first member, and the through hole is an outer peripheral edge portion connecting the two side edge portions and the outer peripheral side and the inner peripheral side of the through hole. The composite gear according to claim 7, which is defined by the inner peripheral edge portion. The composite gear according to claim 8, wherein the outer peripheral edge portion and / or the inner peripheral edge portion has a curved shape. The composite gear according to claim 8, wherein the side edge portion, the outer peripheral edge portion, and / or the inner peripheral edge portion are continuous via a curved corner portion. The composite gear according to claim 10, wherein the curved shape of the corner is a cylindrical surface or a chamfer. A composite gear in which the angle φ (degree) formed by the two side edges of the through hole satisfies the following.
However, claim 6 indicates that l [mm] is the length from the outermost peripheral surface of the first member to the outer peripheral edge of the through hole, and t [mm] is the thickness of the web of the first member. The composite gear described in. The composite gear according to claim 1, wherein the first member has a holding portion that holds a part of the second member from both sides in the axial direction. The first member has a first holding portion that holds a part of the second member from both sides in the axial direction, and the second member holds a part of the first member on the shaft. The composite gear according to claim 1, which has a second holding portion that is held from both sides in the direction. Photosensitive drum and
A cartridge for an image forming apparatus, comprising the composite gear according to claim 1, which is attached to an end portion of the photosensitive drum in the longitudinal direction and transmits a rotational force to the photosensitive drum. An image forming apparatus comprising the cartridge according to claim 15 and an image forming mechanism for forming an image using the photosensitive drum of the cartridge. In molding dies used to manufacture compound gears
The composite gear is
A first member having a rotating shaft portion and a disk-shaped web extending radially from the rotating shaft portion,
A second member having at least one or more meshing teeth on the outer periphery and supported by the web and provided so as to surround the outer periphery of the first member.
The outermost peripheral surface of the first member has a radial space between the first member and the second member, and the innermost peripheral surface of the second member has a radial space between the first member and the first member. The first member and at least one of the second members are formed so as to sandwich the other of the first member and the second member from both sides in the axial direction of the rotating shaft portion. And
The molding die has a first fixed mold, a second fixed mold, and a moving mold, and the moving mold faces the first fixed mold. After the first member is molded and the first member is molded, the moving mold is moved to a position facing the second fixed mold so as to be integrated with the first member. A molding die configured so that the second member is molded. A first step of forming a first member having a rotating shaft portion and a disk-shaped web extending in the radial direction from the rotating shaft portion.
The first member molded in the first step is housed in a molding die, and the second member having at least one meshing tooth on the outer circumference is supported by the web and the outer circumference of the first member is supported. Including a second step of forming so as to surround
In the second step, the outermost peripheral surface of the first member has a radial space between the first member and the second member, and the innermost peripheral surface of the second member is the same as the first member. There is a radial space between the first member and at least one of the second members, and the other of the first member and the second member is on both sides of the rotating shaft portion in the axial direction. A method for manufacturing a composite gear that forms the second member so as to be sandwiched between the two members.