JP2012106391A - Resin molding method and resin product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent occurrence of cracks at an edge of a shaft hole of a resin product.SOLUTION: In the resin molding method for molding a disk-shaped resin product having a shaft hole, the shaft hole includes an axially extending edge on the inner periphery. In a cavity 29 of molding dies 18, 19 or the like, a resin basin 31 is provided so as to cover a portion corresponding to one end of the shaft hole. A sprue 30 for injecting a molten resin from the outside is provided at the center of the resin basin 31. The side opposite to the sprue of the resin basin 31 is branched to a plurality of legs 31a, and each leg 31a is disposed separately from the portion corresponding to the edge of the shaft hole. The molten resin containing glass fibers is injected to the resin basin 31 through the sprue 30, and the molten resin is charged to the cavity 29 through each leg 31a of the resin basin 31.

Description

  The present invention relates to a resin molding method for molding a disk-shaped resin product having a shaft hole, and a resin product molded by the resin molding method.

  Conventionally, as this type of technique, for example, a method for manufacturing a resin impeller described in Patent Document 1 below can be cited. This technique relates to a method of manufacturing a resin product having a disk shape having a shaft hole in the center, and a resin reservoir opening in a ring shape is provided at the peripheral portion of the portion corresponding to the shaft hole of the cavity, and the resin reservoir A pinpoint gate is provided in the center. Then, after the molten resin is injected into the resin reservoir from the pinpoint gate, the cavity is filled from the resin reservoir through the ring-shaped gate. At this time, the molten resin flows radially evenly from the inside to the outside of the cavity, effectively suppressing the generation of weld lines and increasing the flatness and strength.

JP 2003-181884 A JP-A-9-158885 JP-A-10-259789

  By the way, about the manufacturing method of patent document 1, it is possible to make the shape of the shaft hole of the resin product shape | molded into cross-sectional D shape. In addition, the molten resin injected into the resin reservoir portion described above needs to be cut as surplus meat after resin molding. Therefore, in the shaft hole having a D-shaped cross section, there are two edges on the inner periphery thereof, and therefore there is a possibility that the stress of the molded product changes and a crack occurs at the edge when cutting excess meat. .

  This invention is made in view of the said situation, The objective is to provide the resin molding method and resin product which can prevent generation | occurrence | production of the crack in the edge of the shaft hole of a resin product.

  In order to achieve the above object, the invention described in claim 1 is a resin molding method for molding a disk-shaped resin product having a shaft hole, and the shaft hole has an edge extending in an axial direction on an inner periphery thereof. In the cavity of the mold, a resin reservoir is provided so as to cover a portion corresponding to one end of the shaft hole, a sprue for injecting molten resin from the outside is provided in the resin reservoir, and the resin reservoir is counteracted. The sprue side is branched into a plurality of legs, and each leg is arranged away from the portion corresponding to the edge of the shaft hole, and molten resin containing glass fiber is injected from the sprue into the resin reservoir, and each resin reservoir is The purpose is to fill the cavity with the molten resin from the legs.

  According to the configuration of the above invention, the molten resin containing glass fibers injected from the sprue into the resin reservoir is filled into the cavity from the legs branched into a plurality of resin reservoirs, so that the resin flow around the shaft hole And the orientation of the glass fiber tends to be inclined obliquely with respect to the axial direction of the shaft hole, and the resin shrinkage balance around the shaft hole is improved. In addition, since each leg of the resin reservoir portion is disposed away from the portion corresponding to the edge of the shaft hole, the resin flow near the edge and the orientation of the glass fiber are easily oriented obliquely with respect to the edge. Further, since the resin reservoir portion is branched into a plurality of legs, the volume of the resin reservoir portion is reduced by the branched amount.

  In order to achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, after the molten resin filled in the cavity is cooled, the mold is opened and the resin molded product is taken out. After that, the purpose is to cut the excess meat formed in the resin reservoir.

  According to the configuration of the invention described above, in addition to the action of the invention according to claim 1, the surplus meat formed in the resin reservoir is removed by cutting, and both ends of the shaft hole are opened.

  In order to achieve the above object, in the invention described in claim 3 according to the invention described in claim 1 or 2, it is preferable that the resin reservoir has at least three legs.

  In order to achieve the above object, a fourth aspect of the present invention is a resin product molded by the resin molding method according to any one of the first to third aspects, wherein the resin product is molded against the edge of the shaft hole. The purpose is that the orientation of the glass fibers is oblique or perpendicular.

  According to the configuration of the above invention, since the orientation of the glass fiber is oblique or perpendicular to the edge of the shaft hole, the strength of the edge in the circumferential direction is improved and the stress applied to the edge is also reduced.

  According to invention of Claim 1, generation | occurrence | production of the crack in the edge of the shaft hole of a resin product can be prevented. Moreover, the amount of molten resin remaining in the resin reservoir can be reduced, and the yield of the resin material used for the resin product can be improved.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, a rotating shaft such as a motor can be passed through the shaft hole.

  According to invention of Claim 4, generation | occurrence | production of the crack in the edge of the shaft hole of a resin product can be prevented.

The top view which concerns on 1st Embodiment and shows an impeller. FIG. 3 is a cross-sectional view schematically showing a mold apparatus including an injection mold according to the embodiment. Sectional drawing which expands and shows the part of the chain line square of FIG. 2 about a part of mold apparatus concerning the embodiment. FIG. 4 is a cross-sectional view taken along line AA of FIG. 3 showing a part of the mold apparatus according to the embodiment. The flowchart which shows the procedure of the resin molding method according to the embodiment. FIG. 4 is a cross-sectional view showing a state in which molten resin is injected and filled into the cavity or the like shown in FIG. 3 according to the same embodiment. The top view which shows the center part of the resin molded product which concerns on the same embodiment and was released. The BB sectional drawing of FIG. 7 which concerns on the embodiment and shows the center part of the resin molded product. The perspective view which fractures | ruptures and shows the center part of the resin molded product concerning the embodiment. The top view which shows the center part of the resin molded product of the state which concerns on the embodiment and remove | eliminated the gate. The CC sectional view taken on the line of FIG. 10 which shows the center part of the resin molded product according to the same embodiment. The conceptual diagram which shows a simulation result regarding the orientation (resin flow direction) of the glass fiber in the center part of the cavity according to the same embodiment. FIG. 13 is a conceptual diagram illustrating the conceptual diagram of FIG. 12 in a slightly rotated state according to the embodiment. The conceptual diagram according to FIG. 12 which shows the orientation (direction of the resin flow) of glass fiber according to the conventional example which uses the conventional resin reservoir part and the ring-shaped gate. The conceptual diagram according to FIG. 13 which concerns on the prior art example using the conventional resin reservoir part and a ring-shaped gate, and shows the orientation (direction of resin flow) of glass fiber. The conceptual diagram according to FIG. 12 which concerns on the prior art example which uses a pinpoint gate, and shows the orientation (direction of resin flow) of glass fiber. The conceptual diagram according to FIG. 13 which concerns on the prior art example which uses a pinpoint gate, and shows the orientation (direction of resin flow) of glass fiber. The conceptual diagram which concerns on 1st Embodiment and shows the simulation result of the deformation amount in the periphery of the shaft hole of a resin molded product by a cross section. The conceptual diagram of the DD line cross section of FIG. 18 which concerns on the embodiment and shows the periphery of a shaft hole. FIG. 19 is a conceptual diagram according to FIG. 18 showing the periphery of a shaft hole of a resin molded product according to a conventional example using a conventional resin reservoir and a ring-shaped gate. The conceptual diagram of the EE sectional view of Drawing 20 showing the circumference of a shaft hole concerning the conventional example which used the conventional resin reservoir and the ring-shaped gate. The conceptual diagram according to FIG. 18 which shows the periphery of the shaft hole of a resin molded product in the prior art example which uses a pinpoint gate. The conceptual diagram of the plane which shows the state which looked at the periphery of a shaft hole from the upper side of FIG. 22 according to the prior art which uses a pinpoint gate. The conceptual diagram which concerns on 1st Embodiment and shows the simulation result of the volumetric shrinkage rate which fractured | ruptured the periphery of the shaft hole of the resin molded product by a cross section. The conceptual diagram according to FIG. 24 which shows the simulation result of the volume shrinkage rate in the related art which uses the conventional resin reservoir and the ring-shaped gate. The conceptual diagram according to FIG. 24 which concerns on the prior art example which uses a pinpoint gate, and shows the simulation result of a volumetric shrinkage rate. Sectional drawing according to FIG. 3 which concerns on 2nd Embodiment and shows a part of die apparatus. The FF sectional view taken on the line of FIG. 27 which shows the gate part concerning the embodiment.

<First Embodiment>
Hereinafter, a first embodiment of a resin molding method and a resin product according to the present invention will be described in detail with reference to the drawings.

  In this embodiment, the resin product of the present invention is described as an “impeller” used in a fuel pump, and the resin molding method of the present invention is embodied as a resin molding method in which the impeller is injection-molded with a resin. .

  FIG. 1 is a plan view of an impeller 1. The impeller 1 is an important functional part of a fuel pump, and is formed in a disk shape using resin (PPS) as a main material. The impeller 1 includes a boss 4 including a shaft hole 2 having a D-shaped cross section and three communication holes 3 arranged around the shaft hole 2 at the center thereof. The shaft hole 2 includes two edges 2a extending in the axial direction on the inner periphery thereof. The impeller 1 includes a large number of blades 5 arranged along the outer periphery thereof.

  FIG. 2 schematically shows a mold apparatus 11 including an injection mold according to this embodiment in a sectional view. FIG. 2 shows the mold clamping state of the mold apparatus 11. The mold apparatus 11 includes a first mold 18 and a second mold 19 that form a pair for injection molding. The second mold 19 is assembled with inserts 26 and 27 corresponding to the shaft hole 2 and the communication hole 3 at the center thereof. The second mold 19 is assembled with an eject pin 28 for taking out a resin molded product after molding.

  As shown in FIG. 2, the impeller 1 that is a resin molded product between the molds 18 and 19 and the inserts 26 and 27 in a state where the molds 18 and 19 and the inserts 26 and 27 are clamped to each other. A space (cavity) 29 for forming the is formed. Further, a sprue 30 for injecting and filling molten resin into the cavity 29 is formed in the first mold 18. In this embodiment, a resin (PPS) in which glass fibers are blended is used as the resin material.

  FIG. 3 is an enlarged cross-sectional view of a part of the mold apparatus 11 and a portion indicated by a chain line square S1 in FIG. 4 shows a part of the mold apparatus 11 by a cross-sectional view taken along line AA of FIG. As shown in FIGS. 3 and 4, in the cavity 29 of the mold apparatus 11, a portion corresponding to the central portion of the impeller 1 is a portion corresponding to one end of the shaft hole 2, that is, a portion corresponding to the tip of the nest 26. A resin reservoir 31 is provided so as to cover the tip of the insert 26. The sprue 30 described above is provided so as to intersect perpendicularly with respect to the upper center of the resin reservoir 31. As shown in FIG. 4, the anti-sprue side of the resin reservoir 31 is formed by branching into a plurality (three in this embodiment) of legs 31a. And each leg 31a is arrange | positioned apart from the part corresponding to the edge 2a of the shaft hole 2, ie, the edge 26a of the outer periphery of the nest | insert 26, more than predetermined distance.

  Next, a resin molding method for the impeller 1 performed using the mold apparatus 11 described above will be described. FIG. 5 is a flowchart showing the procedure of the resin molding method. FIG. 6 is a sectional view showing a state in which the molten resin 10 is injected and filled into the cavity 29 and the like shown in FIG.

  First, as shown in FIG. 5 (1), mold clamping is performed. In this clamped state, as shown in FIGS. 2 and 3, a cavity 29 is formed between both molds 18 and 19 and the inserts 26 and 27.

  Next, as shown in FIG. 5B, the molten resin 10 is injected and filled. That is, as shown in FIG. 6, the molten resin 10 containing glass fibers is injected and filled into the cavity 29 through the sprue 30. At this time, the molten resin 10 is injected from the sprue 30 into the resin reservoir 31 so that the cavity 29 is filled with the molten resin from each leg 31 a of the resin reservoir 31.

  Thereafter, as shown in FIG. 5 (3), cooling is performed. That is, it waits for the molten resin 10 injected and filled into the cavity 29 to cool and harden.

  When the cooling is completed, the mold is opened as shown in FIG. That is, the second mold 19 that is a movable mold is moved backward for mold opening.

  Then, as shown in FIG. 5 (5), mold release is performed. That is, by ejecting the eject pin 28 in the direction of the first mold 18 that is a fixed mold, the resin molded product is extracted from the tip of the second mold 19.

  FIG. 7 is a plan view showing a central portion of the released resin molded product 41. In FIG. 8, the center part of the resin molded product 41 is shown by the BB sectional drawing of FIG. In FIG. 9, the center part of the resin molded product 41 is fractured and shown in a perspective view. As shown in FIGS. 7 to 9, the surplus meat (gate) 42 corresponding to the resin reservoir 31 remains on the boss 4 of the resin molded product 41.

  Next, as shown in FIG. 5 (6), gate processing is performed. That is, the gate 42 is removed by cutting. FIG. 10 is a plan view showing the central portion of the resin molded product 41 with the gate 42 removed. In FIG. 11, the center part of the resin molded product 41 is shown by CC sectional view taken on the line of FIG.

  Thereafter, as shown in FIG. 5 (7), other deburring is performed, and as shown in FIG. 5 (8), "annealing", that is, the resin molded product 41 is reheated, thereby completing the impeller 1. Get the goods.

  As described above, in this embodiment, the disk-shaped impeller 1 having the shaft hole 2 having the D-shaped cross section is formed by the resin molding method described above. Here, the shaft hole 2 includes two edges 2a extending in the axial direction on the inner periphery thereof. In the cavity 29 of the mold apparatus 11, a resin reservoir 31 is provided at a portion corresponding to one end of the shaft hole 2, that is, a portion corresponding to the tip of the insert 26 so as to cover the tip of the insert 26. A sprue 30 for injecting the molten resin 10 from the outside is provided at the center of the resin reservoir 31. Further, the anti-sprue side of the resin reservoir 31 is formed to be branched into three legs 31a. Each leg 31 a is disposed at a predetermined distance from a portion corresponding to the edge 2 a of the shaft hole 2, that is, the outer edge 26 a of the insert 26. Then, the molten resin 10 containing glass fiber is injected from the sprue 30 into the resin reservoir 31, and the cavity 29 is filled with the molten resin 10 from each leg 31 a of the resin reservoir 31.

  Further, in this embodiment, after the molten resin 10 filled in the cavity 29 is cooled, the mold apparatus 11 is opened and the resin molded product 41 is taken out, and then the surplus meat corresponding to the resin reservoir portion 31, that is, The gate 42 is cut by “gate processing”.

  Here, the resin flow and the glass fiber orientation in the above-described resin molding method will be described. FIG. 12 is a conceptual diagram showing simulation results for the orientation of glass fibers (direction of resin flow) in the central portion of the cavity 29 according to this embodiment. The vertical strip scale on the right side of the figure expresses the degree of orientation of the glass fiber by shading. The direction of the glass fiber in the figure is expressed by the difference in the width and length of the rhombus, as shown in the outline in the square frame below the scale. 13 to 17 described later, the summary in the scale and the square frame is the same as that in FIG. FIG. 13 shows the conceptual diagram of FIG. 12 in a slightly rotated state according to this embodiment. FIG. 14 relates to a conventional example using a conventional resin reservoir and a ring-shaped gate, and shows the orientation (direction of resin flow) of the glass fiber by a conceptual diagram similar to FIG. FIG. 15 is a conceptual diagram similar to FIG. 13 showing the orientation of glass fibers (direction of resin flow) in a conventional example using a conventional resin reservoir and a ring-shaped gate. FIG. 16 is a conceptual diagram similar to FIG. 12 showing the orientation of glass fibers (the direction of resin flow) in a conventional example in which a molten resin is injected from the outside of the insert 26 using a pinpoint gate. FIG. 17 is a conceptual diagram according to FIG. 13 showing the orientation of glass fibers (the direction of resin flow) in a conventional example in which a molten resin is injected from the outside of the insert 26 using a pinpoint gate.

  In this embodiment, as shown by thick arrows in FIGS. 12 and 13, it can be seen that the molten resin and its glass fiber 51 flow downward from the legs 31 a of the resin reservoir 31 to the cavity 29. Further, as shown in FIG. 13, it can be seen that the orientation of the glass fiber 51 is oblique or perpendicular to the edge 26 a at the portion of the edge 26 a of the insert 26 corresponding to the edge 2 a of the shaft hole 2.

  On the other hand, in the conventional example using the conventional resin reservoir and the ring-shaped gate, the molten resin and its glass fiber 51 are directed downward from the resin reservoir to the cavity 29 as shown by thick arrows in FIGS. You can see that it flows. Further, as shown in FIG. 15, it can be seen that the orientation of the glass fiber 51 is substantially parallel to the edge 26 a in the portion of the edge 26 a of the insert 26 corresponding to the edge 2 a of the shaft hole 2.

  On the other hand, in the conventional example using a pinpoint gate, it can be seen that the molten resin and its glass fiber 51 flow laterally in the cavity 29 as shown by thick arrows in FIG. Moreover, as shown in FIG. 17, it can be seen that the orientation of the glass fiber 51 intersects the edge 26a substantially perpendicularly at the edge 26a portion of the insert 26 corresponding to the edge 2a of the shaft hole 2.

  Here, the deformation state of the resin molded product before “gate processing” will be described. FIG. 18 relates to the present embodiment, and shows a simulation result of a deformation amount around the shaft hole 2 of the resin molded product 41 by a cross-sectional conceptual diagram. In FIG. 19, the periphery of the shaft hole 2 is shown by the conceptual diagram of the DD sectional view of FIG. FIG. 20 is a conceptual diagram similar to FIG. 18 showing the periphery of the shaft hole 2 of the resin molded product 61 according to a conventional example using a conventional resin reservoir and a ring-shaped gate. In FIG. 21, the periphery of the axial hole 2 is shown with the conceptual diagram of the EE sectional view of FIG. FIG. 22 relates to a conventional example using a pinpoint gate, and shows the periphery of the shaft hole 2 of the resin molded product 71 by a conceptual diagram similar to FIG. In FIG. 23, the periphery of the axial hole 2 is shown with the conceptual diagram of the plane seen from the upper side of FIG.

  In this embodiment, as shown by a two-dot chain line in FIG. 18, it can be seen that the deformation of the shaft hole 2 makes its inner peripheral wall nearly vertical. On the other hand, in the conventional example using the conventional resin reservoir 81 and the ring-shaped gate, as shown by the two-dot chain line in FIG. I understand that Further, in the conventional example using the pinpoint gate, as shown by a two-dot chain line in FIG. 22, it can be seen that the deformation of the shaft hole 2 has a C-shaped inner peripheral wall. 20 to 23, “61, 71” indicates a conventional resin molded product, and “62” indicates a conventional gate (the same applies hereinafter).

  The volume shrinkage of the resin molded product before “gate processing” will be described. In FIG. 24, the simulation result of the volume shrinkage | contraction rate which fractured | ruptured the periphery of the shaft hole 2 of the resin molded product 41 in connection with this embodiment is shown with the conceptual diagram of a cross section. FIG. 25 relates to a conventional example using a conventional resin reservoir and a ring-shaped gate, and shows a simulation result of the volume shrinkage rate with a conceptual diagram similar to FIG. FIG. 26 relates to a conventional example using a pinpoint gate, and shows a simulation result of the volume shrinkage rate with a conceptual diagram similar to FIG.

  In this embodiment, as shown in FIG. 24, for the edge 2a of the shaft hole 2, the contraction rate of the sprue side AS and the contraction rate of the anti-sprue side BS are medium and the same. From this, as shown in FIG. 18, it is thought that the inner peripheral wall of the shaft hole 2 becomes nearly vertical. On the other hand, in the conventional example using the conventional resin reservoir ring-shaped gate, as shown in FIG. 25, the shrinkage rate of the sprue side AS is smaller than the shrinkage rate of the anti-sprue side BS. From this, as shown in FIG. 20, it is thought that the inner peripheral wall of the shaft hole 2 is deformed into a reverse C shape.

  Furthermore, as shown in FIGS. 24 to 26, since the shrinkage rate of the outer thick portions of the resin molded products 41, 61, 71 is larger than that of the inner thick portions, the resin molded products 41, 61, 71 At the time of solidification, the periphery of the shaft hole 2 is pressed from the outside. Here, as shown in FIGS. 24 and 25, when the gates 42 and 62 are provided, the rigidity of the resin molded products 41 and 61 is increased accordingly. For this reason, even if the outer thick part of the resin molded products 41 and 61 contracts, the edge 2a of the shaft hole 2 does not crack. However, when the gates 42 and 62 are cut, the rigidity of the portions is lost and the gates 42 and 62 are deformed. In particular, in the conventional example shown in FIG. 25, since the shrinkage rate of the sprue side AS of the shaft hole 2 is smaller than the shrinkage rate of the anti-sprue side BS, the stress tends to be high at that portion, and in the sprue side AS where the stress is concentrated, There is a risk of cracks entering the edge 2a. On the other hand, in the conventional example using a pinpoint gate, the gate processing of the gates 42, 46, etc. is not required, so that there is no change in rigidity. Further, as shown in FIG. Since the shrinkage rate of the side BS is medium, the stress is low and the risk of cracking is small.

  According to the resin molding method of this embodiment described above, the molten resin 10 blended with glass fibers injected from the sprue 30 into the resin reservoir 31 is separated from the legs 3a branched into three of the resin reservoir 31 from the cavity 29. 12 and 13, the resin flow around the nest 26 corresponding to the shaft hole 2 and the orientation of the glass fibers 51 are easily inclined obliquely with respect to the axial direction of the nest 26. For this reason, about the impeller 1 after shaping | molding, the intensity | strength with respect to the circumferential direction of the shaft hole 2 can be improved. Further, since each leg 31a of the resin reservoir 31 is disposed away from the edge 26a of the insert 26 corresponding to the edge 2a of the shaft hole 2, the resin shrinkage balance around the insert 26 is improved, and the impeller 1 after molding Therefore, the stress applied to the edge 2a of the shaft hole 2 can be reduced, and the stress release after the resin reservoir 31 is cut can be reduced. In this sense, generation of cracks at the edge 2a of the shaft hole 2 can be prevented.

  In the resin molding method of this embodiment, since the resin reservoir 31 is branched into the plurality of legs 31a, the volume of the resin reservoir 31 is reduced by the amount of the branch. In this sense, the amount of molten resin remaining in the resin reservoir 31 can be reduced, and the yield of the resin material used for the impeller 1 can be improved.

  Moreover, in the resin molding method of this embodiment, the surplus meat corresponding to the resin reservoir 31, that is, the gate 42 that closes the shaft hole 2 is removed by cutting, and both ends of the shaft hole 2 are opened. For this reason, the shaft of the motor 2 can be assembled by passing through the shaft of the motor.

  Furthermore, according to the impeller 1 of this embodiment, since the orientation of the glass fiber 51 is oblique or perpendicular to the edge 2a of the shaft hole 2 having a D-shaped cross section, the strength of the edge 2a in the circumferential direction is improved. The stress applied to the edge 2a is also reduced. For this reason, generation | occurrence | production of the crack in the edge 2a of the shaft hole 2 of the impeller 1 can be prevented.

Second Embodiment
Next, a second embodiment in which the resin molding method and the resin molded product according to the present invention are embodied will be described in detail with reference to the drawings.

  This embodiment differs from the first embodiment mainly in the shape of the resin reservoir. FIG. 27 shows a part of the mold apparatus in a sectional view according to FIG. FIG. 28 shows the resin reservoir 32 by a cross-sectional view taken along line FF in FIG. In this embodiment, with respect to a normal resin reservoir portion 81 (indicated by a solid line and a two-dot chain line in FIG. 28) formed so as to surround the periphery of the insert 26, the inner peripheral edge of the resin reservoir portion 81 and the insert 26 The resin reservoir 32 of this embodiment is formed by dividing a part of the D-shaped belt-like portion formed between the outer peripheral edge and the first mold 18 by the meat. What is divided is a portion 18 a corresponding to the apex of the nest 26 having a D-shaped cross section and two portions 18 b and 18 c corresponding to the edge 26 a of the nest 26. By being divided in this way, the anti-sprue side of the resin reservoir 32 is formed to be branched into three legs 32a, and each leg 32a is separated from the corresponding portion of the edge 2a of the shaft hole 2, that is, the edge 26a of the insert 26. Arranged.

  Therefore, also in this embodiment, the same effects as those in the first embodiment can be obtained by performing the same resin molding method as in the first embodiment using the above-described mold apparatus.

  The present invention is not limited to the above-described embodiments, and a part of the configuration can be changed as appropriate without departing from the spirit of the invention.

  (1) In the above-described embodiments, three legs 31a and 32a of the resin reservoirs 31 and 32 are provided. However, the number of legs can be 1, 2, or 4 or more.

  (2) In each of the embodiments described above, the shaft hole 2 has a D-shaped cross section, but the cross-sectional shape is not limited as long as the shaft hole has an edge extending in the axial direction of the shaft hole.

  The present invention can be used for manufacturing a resin impeller constituting a fuel pump.

1 Impeller (resin product)
2 Shaft hole 2a Edge 10 Molten resin 11 Mold device 18 First mold 18a Part 18b Part 18c Part 26 Nest 26a Edge 29 Cavity 30 Sprue 31 Resin reservoir 31a Leg 32 Resin reservoir 32a Leg 41 Resin molded product 42 Gate (Excess meat)
51 glass fiber

Claims (4)

A resin molding method for molding a disk-shaped resin product having a shaft hole,
The shaft hole includes an edge extending in an axial direction on an inner periphery thereof,
In the cavity of the mold, a resin reservoir is provided so as to cover a portion corresponding to one end of the shaft hole, and a sprue for injecting molten resin from the outside is provided in the resin reservoir. The anti-sprue side is branched into a plurality of legs, and each leg is arranged away from a portion corresponding to the edge of the shaft hole,
A resin molding method characterized by injecting molten resin containing glass fibers from the sprue into the resin reservoir, and filling the cavity with the molten resin from the legs of the resin reservoir.   After the molten resin filled in the cavity is cooled, the mold is opened and a resin molded product is taken out, and then the excess meat molded in the resin reservoir is cut. The resin molding method according to claim 1.   The resin molding method according to claim 1, wherein the number of the legs of the resin reservoir is at least three. A resin product molded by the resin molding method according to any one of claims 1 to 3,
A resin product characterized in that the orientation of the glass fiber is oblique or perpendicular to the edge of the shaft hole.