JP2022164242A - Method for manufacturing resin gear and resin gear - Google Patents

Abstract

To provide a method for manufacturing a resin gear that can increase a strength of the resin gear.SOLUTION: A method for manufacturing a resin gear 1 having an annular resin member 9 and a metal bush 8 using a resin gear molding material 6, comprises: a first step of filling the resin gear molding material 6 into a mold 20 and applying pressure to form a preform 25 as an annular first intermediate; a second step of placing two pre-forms 25 and the metal bushing 8 between a lower mold 30B and an upper mold 30T and heating and compressing a resulting material to form a molded product 40 as an annular second intermediate; and a third step of forming a tooth profile 9a by performing gear cutting in an outer peripheral portion of the molded product 40. In the second step, recesses 25x and recesses 25y are formed at a plurality of planned cutting locations in gear cutting by using a plurality of first protrusions 33x of the upper mold 30T and a plurality of second protrusions 31x of the lower mold 30B.SELECTED DRAWING: Figure 9

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a resin gear and a resin gear.

Resin gears are lightweight and excellent in quietness, and are widely used, for example, as gears for vehicles or for industrial use. As a method for manufacturing such a resin gear, a method using a resin gear molding material containing fibers and a thermosetting resin is known. For example, the manufacturing method described in Patent Document 1 includes steps of dispersing phenolic resin powder and aramid fiber in water and making paper to obtain a sheet-like molding material, cutting the obtained molding material into a gear shape, and a step of compression-molding a preform formed by laminating a plurality of the preforms while heating.

JP 2014-51097 A

In recent years, in the above-described technology, there are cases where high strength is desired for resin gears.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for manufacturing a resin gear that can increase the strength of the resin gear, and to provide a resin gear that has been increased in strength.

A method for manufacturing a resin gear according to one aspect of the present invention is a method for manufacturing a resin gear having an annular resin member and a metal bush using a molding material for a resin gear. A first step of filling a mold with a molding material and pressurizing it to form a first annular intermediate, placing the first intermediate and the metal bush between the upper mold and the lower mold and compressing them under heat, a second step of forming an annular second intermediate; The first protrusion and the plurality of second protrusions of the lower mold form recesses at a plurality of planned cutting locations in gear cutting.

According to the method for manufacturing a resin gear according to one aspect of the present invention, in the second step of forming the annular second intermediate, the plurality of first protrusions possessed by the upper die and the lower die possessed A plurality of recesses are formed at a plurality of planned cutting locations in gear cutting by the plurality of second projections. A region in which such a concave portion is formed has a high compressibility of the resin. By increasing the compressibility of the resin in the areas where the recesses are formed, the filling rate of the fibers in the areas surrounding the recesses is increased. As a result, it is possible to improve the strength of the resin in the peripheral area of the recess, that is, in the area where the tooth profile is formed after gear cutting. As described above, according to the method for manufacturing a resin gear according to an aspect of the present invention, it is possible to increase the strength of the manufactured resin gear.

In the method for manufacturing a resin gear according to one aspect of the present invention, in the second step, a plurality of recesses may be formed over the entire circumferential region of the second intermediate. Thereby, the strength of each tooth profile formed in the entire circumferential direction can be appropriately improved.

In the method for manufacturing a resin gear according to one aspect of the present invention, in the second step, the recesses formed by the first protrusions and the recesses formed by the second protrusions are arranged in the circumferential direction of the second intermediate body. may be formed alternately in the In this way, since the concave portions formed by the first convex portions and the concave portions formed by the second convex portions are alternately formed in the circumferential direction, when manufacturing a helical gear having a twisted tooth profile, concave portions corresponding to the respective tooth profiles can be formed. can be properly formed. That is, according to such a manufacturing method, it is possible to suitably manufacture a helical gear in which the strength of each tooth profile is improved.

In the method for manufacturing a resin gear according to an aspect of the present invention, in the second step, the recess may be formed so as to taper toward the bottom side of the recess. By making the concave portion tapered, it becomes easy to overlap the cutting area by gear cutting that forms a twisted tooth profile and the area of the concave portion, and the area whose strength is improved by forming the concave portion is used for later gear cutting. It is possible to suppress cutting by. That is, according to such a manufacturing method, it is possible to suitably manufacture a helical gear in which the strength of each tooth profile is improved.

A resin gear according to an aspect of the present invention includes a metal bush, and an annular resin member provided around the metal bush, and a plurality of resin gears are provided on the outer peripheral portion of the resin member along the circumferential direction. A tooth profile is formed, and in the resin member, at least a part of the region with the tooth profile may have a higher fiber filling rate than the region without the tooth profile. In the resin gear according to one aspect of the present invention, the fiber filling rate is increased in the region where the tooth profile is formed. As a result, the strength of the resin in the area where the tooth profile is formed can be improved.

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the resin gear which can strengthen a resin gear, and the resin gear with which high strength was attained can be provided.

FIG. 1 is a perspective view showing a resin gear according to an embodiment. FIG. 2(a) is a diagram for explaining a method of manufacturing a molding material for a resin gear according to the embodiment. FIG. 2(b) is a diagram showing a continuation of FIG. 2(a). FIG. 3(a) is a photograph showing a molding material for a resin gear according to the embodiment. FIG.3(b) is a photograph figure which expands and shows a part of Fig.3 (a). FIG. 4 is a schematic perspective view showing a mold used for molding the preform according to the embodiment. FIG. 5 is a perspective view showing a preform according to the embodiment. FIG. 6(a) is a schematic cross-sectional view showing a mold for hot compression molding. FIG.6(b) is sectional drawing which shows the molded product as a 2nd intermediate. FIG. 7 is a perspective view showing an upper mold for hot compression molding. FIG. 8 is a perspective view showing a lower mold for hot compression molding. FIG. 9 is a perspective view showing a molded product as a second intermediate after hot compression molding. FIG. 10 is a diagram for explaining the filling rate of fibers in the molded product as the second intermediate. FIG. 11 is a graph showing the relationship between fiber filling ratio (fiber volume ratio) and strength.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and overlapping descriptions are omitted.

As shown in FIG. 1, a resin gear 1 manufactured by the manufacturing method according to the present embodiment is a so-called high-strength resin gear, and is used as a vehicle or industrial gear. For example, the resin gear 1 can be used for balance shaft gears, camshaft gears, etc. in an engine. A resin gear 1 includes a metal bush 8 and a resin member 9 . The resin gear 1 is a helical gear with twisted tooth traces.

The metal bush 8 is a member attached to, for example, a rotating shaft (not shown). The metal bushing 8 is annular. The metal bush 8 is made of metal such as stainless steel. The metal bush 8 is provided with a through hole 8h. A rotary shaft is inserted into the through hole 8h. The resin member 9 is a member that meshes with other gears. The resin member 9 is annular. The resin member 9 is made of resin. The resin member 9 is provided around the metal bush 8 . A plurality of tooth profiles 9a are formed on the outer peripheral portion of the resin member 9 along the circumferential direction. A plurality of tooth profiles 9a are formed over the entire circumference of the resin member 9 at predetermined intervals. As described above, the resin gear 1 is a helical gear, and the tooth profile 9a is obliquely formed with respect to the rotation axis. In the resin member 9, at least a portion of the region where the teeth 9a are formed has a higher fiber filling rate than the region where the teeth 9a are not formed (the portion of the resin member 9 other than the outer peripheral portion). Such a difference in fiber filling rate is realized by the manufacturing method described later (details will be described later).

Next, an example of the manufacturing method according to this embodiment will be described.

The manufacturing method according to the present embodiment includes a manufacturing method for manufacturing a resin gear molding material, which is a molding material for the resin gear 1, and a manufacturing method for manufacturing the resin gear 1 using the resin gear molding material. and a method.

[Manufacturing molding materials for resin gears]
First, a molding material for a resin gear is manufactured. As shown in FIG. 2(a), (i) thermosetting resin powder 2, (ii) wet fiber 3 having a water content of 10 to 25% by weight, and (iii) additive (or filler) A raw material 5 containing 4 and is prepared.

Examples of resin powder 2 include phenol resin, imide resin, melamine resin, and epoxy resin. The resin powder 2 preferably has a particle size of about 1 to 200 μm. As the resin powder 2, one kind of resin or a combination of two or more kinds of resins can be used. The amount of the resin powder 2 in the raw material 5 is preferably 30-80% by weight, more preferably 45-65% by weight.

The wet fibers 3 include, as fibrous substances, first fibers 3P that are para-aramid fibers and second fibers 3M that are meta-aramid fibers. The fiber length of the first fiber 3P is 3 mm±1 mm. The fiber length of the second fibers 3M is longer than the fiber length of the first fibers 3P. The fiber length of the second fibers 3M is at least twice the fiber length of the first fibers 3P. The fiber length of the second fibers 3M is 6 mm±1 mm. Note that the wet fibers 3 may contain other fibrous substances. For example, the wet fibers 3 may contain acrylic fibers, cellulose fibers, carbon fibers, phenol resin fibers, polyimide fibers, inorganic fibers, and the like. Examples of inorganic fibers include carbon fibers, alumina fibers, alumina-silica fibers, glass fibers, mineral fibers, and ceramic fibers.

The fiber volume ratio (fiber volume content ratio) of the raw material 5 is preferably 40% by volume or more, preferably 40 to 60% by volume. The fiber volume ratio is the volume ratio of fibrous substances contained in the raw material 5 . The sum of the volume of the first fibers 3P and the volume of the second fibers 3M is more than half of the total volume of the wet fibers 3. The weight of the wet fibers 3 in the raw material 5 is preferably 25-55% by weight, more preferably 35-45% by weight.

Examples of the additive 4 include montanic acid ester, zinc stearate, talc, silicon rubber, zirconia, alumina, silica, barium sulfate, calcium carbonate, mica, potassium titanate, graphite, antimony trioxide, and disulfide. antimony and the like. The amount of additive 4 in raw material 5 is preferably 0 to 20% by weight, more preferably 0.5 to 15% by weight.

As shown in FIG. 2(b), the raw material 5 is mixed by the mixer 10 for a predetermined time. As a result, the resin gear molding material 6 shown in FIGS. 3(a) and 3(b) is formed. The resin gear molding material 6 partially includes a plurality of fine granular bodies (fiber balls). The resin gear molding material 6 does not have a two-dimensional planar shape but a three-dimensional three-dimensional shape. The mixer 10 and its mixing method are not particularly limited as long as the raw materials can be uniformly mixed. For example, as the mixer 10, a Loedige mixer (manufactured by Loedige) and an Einrich mixer (manufactured by Eirich Japan) can be used.

In this embodiment, an Einrich mixer is used as the mixer 10, as shown in FIG. 2(b). Mixer 10 has base 11 , mixing pan 12 , rotor 13 and blades 14 . The base 11 rotatably supports the mixing pan 12 and rotor 13 . The mixing pan 12 is a container that accommodates the raw material 5 . The rotor 13 is a stirring blade for stirring the raw material 5 . The rotor 13 is arranged within the mixing pan 12 . In such a mixer 10, the rotor 13 rotating at high speed and the rotating mixing pan 12 reduce dead zones in the mixing pan 12. As shown in FIG. In addition, in the mixer 10 as described above, the material that is biased toward the side surface of the mixing pan 12 due to the centrifugal force is scraped off by the blade 14, and the scraped material is brought into contact with the rotor 13 because the mixing pan 12 is inclined. , efficient mixing takes place.

[Manufacturing of resin gears]
Subsequently, the formed resin gear molding material 6 is used to manufacture the resin gear 1 .
(Formation of preform)
First, the resin gear molding material 6 is preformed to form a preform as a first intermediate. Specifically, as shown in FIG. 4, a mold 20 including a lower mold 20B and an upper mold 20T is prepared, and the mold 20 is preheated to 80° C., for example. Lower mold 20B has cylindrical cavity 21 . The upper mold 20T has a cylindrical projection 22 that enters the cavity 21. As shown in FIG.

A necessary amount of the resin gear molding material 6 is weighed, and the cavity 21 of the lower mold 20B is uniformly filled with the resin gear molding material 6 . After filling, for example, force is applied to the upper mold 20T with a press or the like to pressurize the molding material 6 for a resin gear. As a pressing condition, for example, the filled resin gear molding material 6 is pressed at a pressure of 70 MPa for 10 seconds. As a result, as shown in FIG. 5, a preform 25 is formed by preforming the resin gear molding material 6 . After that, the preform 25 is removed from the mold 20 . The preform 25 is, for example, an annular body with an outer diameter of 90 mm and an inner diameter of 60 mm. The filling and pressurization of the resin gear molding material 6 described above are repeated to form two preforms 25 . In this manner, the mold 20 is filled with the resin gear molding material 6 and pressurized to form the annular preform 25 as the first intermediate (first step).

(Heat compression molding)
A tooth forming mold 30 including a lower mold 30B and an upper mold 30T shown in FIG. 6(a) is prepared, and this tooth forming mold 30 is heated to 200±5°C. In addition, in FIG. 6A, illustration of the detailed configuration of the lower mold 30B and the upper mold 30T is omitted (the detailed configuration will be described later with reference to FIGS. 7 and 8). The two preforms 25 are dried in a dryer. The metal bushing 8 is preheated to 90°C in a dryer. The dried preform 25 and metal bushing 8 are cast into a heated tooth forming mold 30 without cooling. In the molding process, two (upper and lower) preforms 25 are placed in a tooth forming die 30 with the protruding portion 8a provided on the outer peripheral surface of the metal bushing 8 sandwiched between them. The molds are clamped in the tooth forming mold 30 and the preform 25 and the metal bushing 8 are heat-compressed. Thereby, a molded product 40 as a second intermediate shown in FIG. 6(b) is formed. In this way, the two preforms 25 and the metal bushing 8 are placed between the lower mold 30B and the upper mold 30T and heat-compressed to form the molded product 40 as the annular second intermediate. (Second step).

In the mold clamping, for example, after holding the molded product 40 at a position 10 mm before the press-off position (target thickness) for 30 seconds, the pressure of 100 MPa is applied to the press-off position to compress it, and this state is held for about 6 minutes to hold the resin. to cure. After that, the molded product 40 is taken out from the tooth forming mold 30, and resin burrs are removed using scissors or the like. Molded article 40 is an annular object. In the molded product 40 , the resin member 9 is composed of two preforms 25 which are heat-compressed.

Here, as shown in FIG. 7, the upper die 30T has a disk-shaped pressing portion 33 that presses the preform 25 from above during heat compression. A plurality of first projections 33x are formed on the pressing portion 33 over the entire circumferential area of the outer peripheral portion thereof. The first convex portion 33x extends toward the lower mold 30B direction (downward). The first convex portion 33x is formed in a tapered shape (tapered shape) toward its lower end. The first protrusion 33x is configured to form a recess 25x (see FIG. 9) in the upper preform 25 due to its shape when the two preforms 25 and the metal bush 8 are heat-compressed. The shape of the first convex portion 33x is set according to the shape of the concave portion 25x desired to be obtained in the molded product 40. As shown in FIG. The position of each first convex portion 33x is set according to the position of each concave portion 25x desired to be obtained in the molded product 40 .

In addition, as shown in FIG. 8, the lower mold 30B has a hollow cylindrical storage portion 31 that stores the preform 25 and the metal bush 8 during heating and compression. A plurality of second convex portions 31x are formed on the bottom surface 31a of the housing portion 31 over the entire circumferential area of the outer peripheral portion thereof. The second convex portion 31x extends in the direction of the upper mold 30T (upward). The second convex portion 31x is formed in a tapered shape (tapered shape) toward its upper end. The second protrusion 31x is configured to form a recess 25y (see FIG. 9) in the lower preform 25 due to its shape when the two preforms 25 and the metal bush 8 are heated and compressed. The shape of the second convex portion 31x is set according to the shape of the concave portion 25y desired to be obtained in the molded product 40. As shown in FIG. The position of each second convex portion 31x is set according to the position of each concave portion 25y to be obtained in the molded product 40. As shown in FIG.

In the second step, the plurality of first protrusions 33x of the upper mold 30T and the plurality of second protrusions 31x of the lower mold 30B are used to form recesses 25x in a plurality of planned cutting locations in gear cutting described later. and recesses 25y are formed (see FIG. 9). That is, in the second step, the recesses 25x and 25y are formed in the portions to be tooth-cut and discarded by the gear-cutting process. In the second step, as shown in FIG. 9 , a plurality of recesses 25 x and a plurality of recesses 25 y are formed over the entire circumference of the molded product 40 .

In the second step, as shown in FIG. 9, the concave portion 25x formed by the first convex portion 33x of the upper mold 30T and the concave portion 25y formed by the second convex portion 31x are arranged around the molded product 40. Form staggered in direction. By cutting along such recesses 25x and 25y, it is possible to appropriately manufacture a helical gear in which the tooth profile 9a is obliquely formed with respect to the rotation axis.

In the second step, the recesses 25x and 25y are formed so as to taper toward the bottom sides of the recesses 25x and 25y. The bottom of the recess 25x is the lower end region of the recess 25x, and the bottom of the recess 25y is the upper end region of the recess 25y.

FIG. 10 is a partially enlarged view of FIG. 9 and is a view for explaining the filling rate of fibers in the molded product 40. As shown in FIG. As shown in FIG. 10, when the recesses 25x and 25y are formed, the compressibility of the resin increases in the areas where the recesses 25x and 25y are formed, and the area where the recesses 25x and 25y are formed increases. The fiber loading increases in the peripheral region. Specifically, for example, an area SA along the shape of the recess 25x and the recess 25y (the area indicated by the thick line in FIG. 10), which is a peripheral area, and an area AA between the recess 25x and the recess 25y (see FIG. 10 The hatched area in ) increases the fiber filling rate. Such a region with a high fiber filling rate has a higher strength than other regions (details will be described later).

Here, when the molded product 40 is cut by gear cutting to be described later so that the concave portions 25x and the concave portions 25y formed alternately in the circumferential direction are connected to each other, for example, two cutting lines CL shown in FIG. The molded product 40 is cut along. In this case, of the area AA between the recess 25x and the recess 25y, the area A1 included between the two cutting lines CL is cut, but the area A2 not included between the two cutting lines CL is cut. It remains without being cut. In addition, since the molded product 40 is cut so that the recesses 25x and the recesses 25y formed alternately in the circumferential direction are continuous, the cutting line CL is oblique with respect to the rotation axis, and the cutting area has a tapered shape. It is easy to overlap the regions of the recess 25x and the recess 25y. As a result, as shown in FIG. 10, the cutting line CL is divided into a partial area S1 of the area SA along the shape of the recess 25x and a partial area S2 of the area SA along the shape of the recess 25y. (more specifically, inside the region A1 and the region S2), and the region S1 and the region S2 can be left even after cutting. In this way, at least part of the high-strength regions (regions A2, S1, and S2 in the example shown in FIG. 10) generated by the formation of the recesses 25x and 25y can be left even after gear cutting. can.

(Gear cutting)
The thickness, outer diameter, and inner diameter of the molded product 40 are processed to predetermined dimensions by lathe processing. The molded product 40 is washed, and the outer periphery of the molded product 40 is gear-cut. Specifically, the molded product 40 is cut (tooth cutting) so that the recessed portions 25x and the recessed portions 25y of the molded product 40 are connected to each other. That is, cutting is performed by aligning the phases of the uneven portions by the tooth forming shape, and finishing the tooth shape with a predetermined dimension. Applied gear cutting includes machining with a hobbing machine or a shaving machine. As a result, a tooth profile 9 a (see FIG. 1) is formed on the outer peripheral portion of the resin member 9 in the molded product 40 . Manufacture of the resin gear 1 is completed by the above.

[Effect]
As described above, the method for manufacturing the resin gear 1 according to the present embodiment uses the resin gear molding material 6 to manufacture the resin gear 1 having the annular resin member 9 and the metal bush 8. A first step of filling the molding material 6 for a resin gear into a mold 20 and pressurizing to form a preform 25 as an annular first intermediate, two preforms 25 and metal A second step of forming a molded product 40 as an annular second intermediate by placing the manufacturing bush 8 between the lower mold 30B and the upper mold 30T and compressing it under heating, and gear cutting at the outer peripheral part of the molded product 40. and a third step of forming the tooth profile 9a by machining. , recesses 25x and recesses 25y are formed at a plurality of planned cutting locations in gear cutting.

According to the method of manufacturing the resin gear 1 according to the present embodiment, in the second step of forming the annular molded product 40, the plurality of first protrusions 33x of the upper mold 30T and the lower mold 30B A plurality of recesses 25x and recesses 25y are formed at a plurality of planned cutting locations in gear cutting by the plurality of second protrusions 31x. A region in which such a concave portion is formed has a high compressibility of the resin. By increasing the compressibility of the resin in the regions where the recesses 25x and 25y are formed, the filling rate of the fibers in the regions surrounding the recesses 25x and 25y increases. As a result, it is possible to improve the strength of the resin in the peripheral area of the recess, that is, in the area where the tooth profile 9a is formed after gear cutting. As described above, according to the method for manufacturing the resin gear 1 according to the present embodiment, it is possible to increase the strength of the manufactured resin gear 1 .

The relationship between fiber filling rate and strength will be described with reference to FIG. FIG. 11 is a graph showing the relationship between fiber filling ratio (fiber volume ratio) and strength. The upper diagram in FIG. 11 shows the relationship between the fiber filling rate (fiber volume rate) and the bending strength, and the lower diagram in FIG. 11 shows the relationship between the fiber filling rate (fiber volume rate) and the impact strength. ing. In order to evaluate the bending strength and impact strength of the resin gear 1 manufactured using the resin gear molding material 6, the bending strength and impact strength of a plurality of test pieces manufactured using the resin gear molding material 6 were measured. A demonstration test for evaluation was conducted. In the demonstration experiment, a plurality of test pieces with different fiber filling ratios (fiber volume ratios) were prepared. FIG. 11 is a graph showing the bending strength and impact strength of these test pieces. The flexural strength was evaluated according to the test methods for flexural strength and flexural modulus described in "JIS K 6911 General Test Methods for Thermosetting Plastics." The impact strength was evaluated according to the flatwise impact test method described in "JIS K 7062 Izod impact test method for glass fiber reinforced plastics".

As shown in the upper diagram of FIG. 11, it can be seen that the bending strength tends to increase as the fiber filling rate (fiber volume ratio) increases. Further, as shown in the lower diagram of FIG. 11, it can be seen that the higher the fiber filling rate (fiber volume ratio), the higher the impact strength tends to be. Thus, the higher the fiber filling rate, the higher the bending strength and the impact strength. Therefore, as described above, according to the method for manufacturing the resin gear 1 according to the present embodiment, which can increase the filling rate of the resin in the region where the tooth profile 9a is formed, the height of the tooth profile 9a in the resin gear 1 can be increased. Strengthening can be realized.

In the method of manufacturing the resin gear 1 according to the present embodiment, in the second step, a plurality of recesses 25x and 25y may be formed over the entire circumference of the molded product 40. FIG. Thereby, the strength of each tooth profile 9a formed in the entire circumferential direction can be appropriately improved.

In the method of manufacturing the resin gear 1 according to the present embodiment, in the second step, the concave portion 25x formed by the first convex portion 33x and the concave portion 25y formed by the second convex portion 31x are formed on the molded product 40. They may be formed alternately in the circumferential direction. Since the recesses 25x formed by the first protrusions 33x and the recesses 25y formed by the second protrusions 31x are alternately formed in the circumferential direction, when manufacturing a helical gear having a twisted tooth profile 9a, each tooth profile The recesses 25x and 25y corresponding to 9a can be appropriately formed. That is, according to such a manufacturing method, it is possible to suitably manufacture a helical gear with improved strength of each tooth profile 9a.

In the case of manufacturing a helical gear, for example, when teeth are formed by compression molding, it is conceivable to fill a mold with a preform that has been preformed into a helical tooth profile to form the teeth. . However, in such a manufacturing method, it is difficult to insert a tooth-shaped preform into a mold, and a problem arises in that the mold structure becomes complicated. In this regard, in the method of manufacturing the resin gear 1 according to the present embodiment, when manufacturing a helical gear, it is not necessary to fill a mold with a preform preformed into a helical tooth shape. , the complication of the mold structure can be avoided.

In the method of manufacturing the resin gear 1 according to the present embodiment, in the second step, the recesses 25x and 25y may be formed so as to taper toward the bottom sides of the recesses 25x and 25y. By tapering the recesses 25x and 25y, it becomes easier for the recesses 25x and the recesses 25y to be overlapped with the areas cut by gear cutting to form the twisted tooth profile 9a and the recesses 25x and 25y. It is possible to suppress that the region whose strength is improved by is cut by later gear cutting. That is, according to such a manufacturing method, it is possible to suitably manufacture a helical gear with improved strength of each tooth profile 9a.

The resin gear 1 according to the present embodiment includes a metal bush 8 and an annular resin member 9 provided around the metal bush 8. At the outer peripheral portion of the resin member 9, a A plurality of teeth 9a may be formed on the resin member 9, and at least a part of the region where the teeth 9a are formed in the resin member 9 may have a higher fiber filling rate than the region where the teeth 9a are not formed. In the resin gear 1 according to this embodiment, the fiber filling rate of the region where the tooth profile 9a is formed is high. As a result, the strength of the resin in the area where the tooth profile 9a is formed can be improved.

Although the method for manufacturing the resin gear 1 and the resin gear 1 according to the present embodiment have been described above, the present invention is not limited to the above embodiment. For example, the resin gear manufactured by the manufacturing method according to one aspect of the present invention may be a spur gear instead of a helical gear. Moreover, the manufacturing method according to one aspect of the present invention may be used in a manufacturing method for manufacturing a resin gear from a paper-molded shaped body formed by a so-called paper-making method.

DESCRIPTION OF SYMBOLS 1... Resin gear, 6... Molding material for resin gear, 8... Metal bush, 9... Resin member, 9a... Tooth profile, 20... Mold (mold), 25... Preform (first intermediate), 25x, 25y... Concave part, 30B... Lower mold, 30T... Upper mold, 31x... Second convex part, 33x... First convex part, 40... Molded product (second intermediate).

Claims (5)

A method for manufacturing a resin gear having an annular resin member and a metal bush using a resin gear molding material,
a first step of filling the molding material for a resin gear into a mold and applying pressure to form an annular first intermediate;
a second step of placing the first intermediate and the metal bush between an upper mold and a lower mold and heating and compressing them to form an annular second intermediate;
A third step of forming a tooth profile by gear cutting in the outer peripheral portion of the second intermediate,
In the second step, recesses are formed at a plurality of planned cutting locations in the gear cutting by a plurality of first projections of the upper mold and a plurality of second projections of the lower mold. , a method for manufacturing a resin gear. 2. The method of manufacturing a resin gear according to claim 1, wherein in said second step, said plurality of concave portions are formed over the entire circumferential region of said second intermediate. In the second step, the recesses formed by the first protrusions and the recesses formed by the second protrusions are alternately formed in the circumferential direction of the second intermediate body. 3. The method for manufacturing a resin gear according to 2. 4. The method of manufacturing a resin gear according to claim 3, wherein in the second step, the recess is formed so as to taper toward the bottom side of the recess. a metal bush;
an annular resin member provided around the metal bush,
A plurality of tooth profiles are formed along the circumferential direction on the outer peripheral portion of the resin member,
In the resin member, at least a part of the region where the tooth profile is formed has a higher fiber filling rate than the region where the tooth profile is not formed.

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