Resin molded product and method for manufacturing a resin molded product

Abstract

To provide a resin molded article and a method for manufacturing the resin molded article capable of evenly filling a thin-wall plate part with a molten resin even when the number of gates is small.SOLUTION: A resin molded article 100 according to the present disclosure is obtained by integrally forming: a plate-like base part 10 having an annular shape in a planar view; a plurality of thin-wall plate parts 20 that extend from one annular surface of the base part 10 in a thickness direction of the base part 10; an annular resin injection part 40 provided radially inside the base part 10 and having gate vestiges 41g; and a resin spreading part 30 that connects the base part 10 and the resin injection part 40 together, and is formed thinner in the thickness direction of the base part 10 than either one of the base part 10 and the resin injection part 40.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a resin molded product having a thin plate portion and a method for manufacturing the resin molded product.

Background Art

[0002] Conventionally, development has been underway to integrally form resin parts having complex shapes using a mold to suppress the number of assembly steps of the parts and the amount of resin used. For example, Patent Document 1 discloses a cross-flow fan in which a plurality of blades, a support plate, and an outer peripheral ring are integrally formed by injection molding or the like. Further, Patent Document 2 discloses a cross-flow fan aimed at suppressing the amount of resin used, reducing weight, and reducing noise by making the molded blades thinner than conventional products.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in a resin molded product having a large number of thin plate-like shapes, such as the above-described cross-flow fan, when the injected molten resin is not evenly filled into the blades, the resin may flow excessively into the blades filled first, causing an overpack. Defects caused by overpacking include burr formation, cracks, mold failure to open, and resin clogging the mold, preventing product removal. In particular, when a product becomes stuck in the mold, it often results in a production stoppage of 2 to 5 days due to the need to remove the clogged resin, which has a significant impact. Therefore, in order to bring the filling balance closer to uniform, it is common to have a configuration with a large number of gate points in the molding of the cross-flow fan described above. In particular, in the case of thin-walled blades as shown in Patent Document 2, the number of gate points is often 12 or more.

[0005] However, when the number of gate points becomes large, a hot runner cannot be used structurally, and since hot runners result in high mold costs, a cold runner must be used. Furthermore, cold runners have disadvantages, such as the waiting time required for the runner to solidify, which increases the molding cycle, and the need for separate work in processes such as runner disposal, which reduces productivity.

[0006] This disclosure has been made in view of these problems, and its purpose is to provide a resin molded product and a method for manufacturing a resin molded product that can uniformly fill a thin plate portion with molten resin even when the number of gate points is small. [Means for solving the problem]

[0007] The resin molded articles disclosed herein are [1] A plate-shaped base portion having an annular shape in plan view, Multiple thin plate portions extending from one annular surface of the base portion along the thickness direction of the base portion, An annular resin injection section having a gate mark is provided on the radially inward side of the base portion, A resin diffusion portion is formed to connect the base portion and the resin injection portion, and is thinner in the thickness direction of the base portion than either the base portion or the resin injection portion. It is characterized by being formed as a single unit.

[0008] Furthermore, the resin molded product of this disclosure is [2] In the configuration described in [1] above, it is preferable that the surface having the gate mark in the annular resin injection section is the surface exposed on the side opposite to the thin plate portion in the thickness direction of the base portion.

[0009] Furthermore, the resin molded product of this disclosure is [3] In the configuration of [1] or [2] described above, it is preferable that the gate marks are provided at equal intervals at multiple locations in the circumferential direction.

[0010] Furthermore, the resin molded product of this disclosure is [4] In any of the configurations described in [1] to [3] above, it is preferable that the ratio of the thickness of the resin diffusion portion to the thickness of the base portion is 10% or more and 40% or less.

[0011] Furthermore, the resin molded product of this disclosure is [5] In any of the configurations described in [1] to [4] above, the ratio of the radial width of the resin injection part to the thickness of the base part is preferably 120% or more and 240% or less.

[0012] Furthermore, the resin molded product of this disclosure is [6] In any of the configurations described in [1] to [5] above, it is preferable that the ratio of the radial width of the resin diffusion portion to the thickness of the base portion is 60% or more and 100% or less.

[0013] Furthermore, the resin molded product of this disclosure is [7] In any of the configurations described in [1] to [6] above, it is preferable that one of the gate marks is located at the same circumferential position as the reference vane.

[0014] Furthermore, the method for manufacturing resin molded articles described herein is: [8] A plate-shaped base portion having an annular shape in plan view, A plurality of thin plate portions extending along the thickness direction of the base portion from one annular surface of the base portion; An annular resin injection portion provided inside the base portion in the radial direction; A resin diffusion portion that connects the base portion and the resin injection portion and is formed thinner in the thickness direction of the base portion than either the base portion or the resin injection portion A method for manufacturing a resin molded product comprising: Injecting molten resin from a gate communicating with the first cavity into the first cavity corresponding to the resin injection portion in a molding die; Spreading the molten resin in the circumferential direction of the first cavity; Diffusing the molten resin in the first cavity into a second cavity corresponding to the resin diffusion portion; Spreading the molten resin into a third cavity corresponding to the base portion and a fourth cavity corresponding to the thin plate portion characterized by including.

Effect of the Invention

[0015] According to the present disclosure, even when the number of gates is small, it is possible to provide a resin molded product and a method for manufacturing a resin molded product that can evenly fill the thin plate portion with molten resin.

Brief Description of the Drawings

[0016] [Figure 1] A perspective view of a resin molded product (fan element) which is an embodiment of the present disclosure. [Figure 2A] A diagram showing the configuration of a cross-flow fan using the resin molded product which is an embodiment of the present disclosure. [Figure 2B] An exploded perspective view showing the configuration of a cross-flow fan using the resin molded product which is an embodiment of the present disclosure. [Figure 3] An enlarged cross-sectional view taken by a plane including the central axis O in FIG. 1. [Figure 4]This is a cross-sectional view of a molding die used in a method for manufacturing a resin molded product, which is one embodiment of the present disclosure. [Figure 5] This flowchart shows the procedure for manufacturing a resin molded article, which is one embodiment of the present disclosure. [Figure 6A] This figure shows the state in which molten resin has begun to diffuse into the first cavity of a molding die used in a method for manufacturing a resin molded product, which is one embodiment of the present disclosure. [Figure 6B] This figure shows the state after the molten resin has been filled into the first cavity of the molding die used in a method for manufacturing a resin molded product, which is one embodiment of the present disclosure. [Figure 6C] This figure shows the state after the molten resin has been filled into the second cavity of the molding die used in a method for manufacturing a resin molded product, which is one embodiment of the present disclosure. [Figure 7] This figure shows the definition of the cross-sectional dimensions of a resin molded product, which is one embodiment of the present disclosure. [Figure 8A] This figure shows a modified example in which a chamfer is provided on the radially outer corner of the resin diffusion portion of a resin molded product, which is one embodiment of the present disclosure. [Figure 8B] This figure shows a modified example in which a chamfer is provided on the radially inner corner of the resin diffusion portion of a resin molded product, which is one embodiment of the present disclosure. [Modes for carrying out the invention]

[0017] The present disclosure will be explained more specifically with reference to the drawings below.

[0018] The resin molded product 100 shown in Figure 1, which is one embodiment of the present disclosure, is a fan element that constitutes a cross-flow fan (assembly 200) (see Figures 2A and 2B) equipped in, for example, air conditioning equipment such as air conditioners or electronic equipment. The resin molded product 100 comprises a base portion 10 that corresponds to the disc portion of the fan element and has an annular shape in plan view (Z-direction positive side view in Figure 1), a thin plate portion 20 that corresponds to the blade of the fan element and extends from one annular surface of the base portion 10 (the annular surface on the Z-direction negative side) along the thickness direction of the base portion 10 toward the tip side (Z-direction negative side), an annular resin injection portion 40 provided on the radially (R-direction in Figure 1) inner side of the base portion 10 and facing the gate 240G of the molding die (see Figure 4), and a resin diffusion portion 30 that connects the base portion 10 and the resin injection portion 40 and is formed to be thinner in the thickness direction of the base portion 10 than either the base portion 10 or the resin injection portion 40 (see Figure 3).

[0019] In this embodiment, the resin molded product 100 is a synthetic resin member in which a base portion 10, a thin plate portion 20, a resin diffusion portion 30, and a resin injection portion 40 are integrally formed, for example, by injection molding.

[0020] In this specification, claims, abstract, and drawings, the upper side (positive Z-direction) in Figure 1 is defined as the base end, and the lower side (negative Z-direction) in Figure 1 is defined as the tip end. Furthermore, radially outward refers to the direction away from the central axis O (positive R-direction in Figure 1) along a straight line passing through and perpendicular to the central axis O of the resin molded product 100 extending vertically in Figure 1, and radially inward refers to the direction toward the central axis O along the said straight line.

[0021] As shown in Figure 1, the base portion 10 has an annular shape with a resin diffusion portion 30 and a resin injection portion 40 on the radially inward side in a plan view, and multiple thin plate portions 20 that function as blades are erected toward the tip side from the annular surface on the tip side (the surface on the negative Z side in Figure 1).

[0022] Multiple insertion grooves 10a are provided in the circumferential direction on the annular surface of the base portion 10 on the base end side (positive Z direction side). These insertion grooves 10a allow multiple resin molded products 100 to be combined in the direction of the central axis O to construct an assembly 200 (cross-flow fan) (see Figures 2A and 2B), as will be described later. The tip of the thin plate portion 20 of the other resin molded product 100 fits into these insertion grooves 10a. As shown in Figure 3, the insertion grooves 10a are formed to a depth exceeding half the thickness of the base portion 10, and the corners are provided with chamfered portions 10b to allow the tip of the thin plate portion 20 to be easily inserted.

[0023] The resin molded product 100 shown in Figure 1 has gate marks 41g, indicated by "x", formed at three locations in the circumferential direction on the base end side (positive Z-direction side) surface 41 of the resin injection section 40. The gate marks 41g are cut marks left on the product side when the solidified resin in the gate 240G, which introduces molten resin into the cavity when the resin molded product 100 is molded by injection molding or the like, is cut by mold opening. In this embodiment, gate marks 41g are formed at approximately equal intervals at three locations in the circumferential direction on the base end side of the resin injection section 40. The number of gates 240G is not limited to this configuration, but it is preferable that gates 240G for introducing molten resin into the cavity are provided at least at two locations in the circumferential direction. This configuration, when combined with the configuration of the resin injection section 40 and resin diffusion section 30 according to this embodiment, can improve the circumferential filling balance.

[0024] Figure 2A is a front view of an assembly 200 (cross-flow fan) constructed by combining resin molded products 100 according to this embodiment in the direction of the central axis O. The assembly 200 comprises a plurality of resin molded products 100 (fan elements) combined in the direction of the central axis O. At the left end of the plurality of resin molded products 100 in Figure 2A, a shaft-equipped element 110 is connected, which has a solid disc-shaped base portion 10 of the resin molded product 100 and a shaft portion S (see also Figure 2B). At the right end of the plurality of resin molded products 100 in Figure 2A, a disc portion 130 into which the tip portion of a thin-walled plate portion 20 can be inserted is provided (see also Figure 2B). As shown in Figure 2B, a fitting hole h is provided in the center of the disc portion 130 into which a drive shaft or the like can be inserted. Note that in Figure 2B, only one of the plurality of resin molded products 100 that are combined is depicted.

[0025] The assembly 200 (cross-flow fan) can be combined with other resin molded products 100 or disc parts 130 by fitting the tip of the thin plate portion 20 (blade) of the resin molded product 100 (fan element) into the insertion groove 10a of the base portion 10 of the other resin molded product 100 or the insertion groove 13a of the disc portion 130. Furthermore, the thin plate portion 21 of the shaft-attached element 110 can be combined with the resin molded product 100 by fitting it into the insertion groove 10a of the resin molded product 100.

[0026] In this embodiment, the thin-walled plate portions 20 are provided on the base portion 10 at random pitches rather than uniform pitches in order to reduce noise generated as the cross-flow fan rotates. Since the thin-walled plate portions 20 are provided at random pitches, the insertion grooves 10a are also provided at the same pitch as the thin-walled plate portions 20. Although the thin-walled plate portions 20 are arranged at random pitches, the difference in pitch is not large enough to be easily distinguishable at a glance, so there is a risk of fitting the tip of a thin-walled plate portion 20 into a different insertion groove 10a. In this embodiment, a reference blade 20s, which has a shorter radial length than the other thin-walled plate portions 20, is provided at only one location in the circumferential direction (see Figure 1), and is configured to be fitted into a reference groove 10as with a shape corresponding to the reference blade 20s on the other resin molded product 100. With this configuration, when the resin molded product 100 is mounted on another resin molded product 100, it is not possible to mount it in a circumferentially misaligned state and fit the tip of a thin-walled plate portion 20 into an insertion groove 10a with a mismatched pitch. In this way, by employing a reference blade 20s that serves as a reference position in the circumferential direction when multiple resin molded products 100 are combined, damage to the blades and interference with the noise characteristics of the blower are prevented.

[0027] The configuration of the reference blade 20s is not limited to the one described above. It may have a longer radial length than the other thin plate sections 20, or its circumferential thickness may differ from that of the other thin plate sections 20. Other configurations may be adopted that allow the circumferential position of the reference blade 20s to be visually distinguished from that of the other thin plate sections 20.

[0028] Next, the manufacturing method of the resin molded product 100 according to this embodiment will be explained using Figures 4 to 6C, etc.

[0029] When manufacturing the resin molded product 100 according to this embodiment, for example, a molding die 300 that molds molten resin supplied from the gate 240G shown in Figure 4 within the cavity can be used. The molding die 300 includes a first cavity 240 for molding the resin injection section 40, a second cavity 230 connected to the radially outer side of the first cavity 240 for molding the resin diffusion section 30, a third cavity 210 positioned radially outer of the second cavity 230 for molding the base section 10, and a fourth cavity 220 extending from the third cavity 210 toward the thickness-direction tip side of the third cavity 210 (downward in Figure 4, negative Z direction) for molding a plurality of thin plate sections 20. Figure 4 is a cross-sectional view of the molding die 300 when cut along a plane including the central axis and the gate 240G.

[0030] As shown in Figure 4, a gate 240G for supplying molten resin into the cavity of the molding die 300 is provided on the base end side (top surface in Figure 4) of the first cavity 240. The gate 240G is provided on the base end side opposite to the fourth cavity 220 that forms the thin plate portion 20.

[0031] In manufacturing the resin molded product 100 according to this embodiment, molten resin is first injected into the first cavity 240, which corresponds to the resin injection section 40, within the molding die 300 shown in Figure 4, from a gate 240G leading to the first cavity 240 (step S101 in Figure 5). The gate 240G is located approximately in the radial center of the base end side surface of the first cavity 240, and is also provided at approximately equal intervals at three locations in the circumferential direction (see Figure 6A, etc.). Preferably, the gate 240G is provided at least at two locations in the circumferential direction, and may be provided at four or more locations. The circumferential position of the gate 240G is the circumferential position of the gate mark 41g of the molded resin molded product 100.

[0032] As shown in Figure 6A, the molten resin injected from the gate 240G into the first cavity 240 diffuses mainly circumferentially within the first cavity 240, and also diffuses slightly into the second cavity 230 radially outward beyond the first cavity 240. As shown in Figure 4, in the molding die 300 according to this embodiment, the second cavity 230 is formed to be thinner in the thickness direction (vertical direction in Figure 4) than the first cavity 240. Therefore, the flow resistance when the molten resin with a predetermined viscosity moves circumferentially within the first cavity 240 is smaller than the flow resistance when it moves radially outward into the second cavity 230 beyond the first cavity 240. For the reasons stated above, the molten resin injected from the gate 240G into the first cavity 240 diffuses selectively mainly in the circumferential direction, and can spread circumferentially within the first cavity 240 before diffusing into the second cavity 230 (step S102 in Figure 5) (see Figure 6B). Therefore, even if gates 240G are placed at only three locations in the circumferential direction as in this embodiment, the first cavity 240 can be filled with relatively uniform pressure in the circumferential direction, as if gates were placed at six or more locations in the circumferential direction.

[0033] Next, the molten resin in the first cavity 240 is diffused into the second cavity 230, which corresponds to the resin diffusion section 30 (step S103 in Figure 5). In this embodiment, as shown in Figure 6B, at the completion of step S102, the molten resin is filled into the first cavity 240, and at a circumferential position near the gate 240G, the molten resin has slightly entered the second cavity 230, which is radially outward. Then, in step S103 in Figure 5, the molten resin further enters the second cavity 230 radially outward, and is diffused into the second cavity 230, becoming completely filled (see Figure 6C).

[0034] At the completion of step S103, as shown in Figure 6C, although a small amount of molten resin has entered the radially outer third cavity 210 at a circumferential position near the gate 240G, the circumferential position dependence of the degree of diffusion of the molten resin is significantly less than immediately after injection, as shown in Figure 6A. Therefore, the molten resin can be distributed relatively evenly in the circumferential direction into the third cavity 210 corresponding to the base portion 10 and the fourth cavity 220 corresponding to the thin plate portion 20 (step S104 in Figure 5).

[0035] As described above, the resin molded product 100 according to this embodiment is configured such that a plate-shaped base portion 10 having an annular shape in plan view, a plurality of thin plate portions 20 extending from one annular surface of the base portion 10 along the thickness direction of the base portion 10, an annular resin injection portion 40 provided on the radially inward side of the base portion 10 and having a gate mark 41g, and a resin diffusion portion 30 connecting the base portion 10 and the resin injection portion 40, and formed thinner in the thickness direction of the base portion 10 than either the base portion 10 or the resin injection portion 40 are integrally formed. By adopting this configuration, when molten resin is injected from the gate 240G into the first cavity 240 forming the resin injection portion 40, the molten resin selectively diffuses in the circumferential direction within the first cavity 240 before diffusing into the second cavity 230, thereby suppressing the circumferential dependence of the filling pressure. Therefore, the occurrence of filling defects due to filling balance is suppressed, and products can be manufactured stably. Furthermore, even if the number of gates 240G is reduced, the resin diffuses sufficiently in the circumferential direction within the first cavity 240 before diffusing into the second cavity 230, thus suppressing the occurrence of filling defects caused by filling imbalance. In addition, the torsional rigidity of the resin molded product 100 can be adjusted by changing the radial and thickness dimensions of the resin injection section 40.

[0036] Furthermore, in this embodiment, the surface of the annular resin injection section 40 having the gate mark 41g is configured to be the surface exposed on the opposite side of the thin plate section 20 in the thickness direction of the base section 10. By adopting such a configuration, the degree of freedom in placement can be increased, especially when a hot runner is used.

[0037] Furthermore, in this embodiment, the gate marks 41g are configured to be provided at approximately equal intervals at multiple locations in the circumferential direction. By adopting this configuration, it is possible to arrange the gates 240G at equal intervals at least two locations in the circumferential direction, thereby suppressing the circumferential dependence of the filling pressure of the molten resin in the resin injection section 40 and suppressing the occurrence of filling defects caused by filling imbalance.

[0038] Furthermore, in this embodiment, the ratio of the thickness of the resin diffusion section 30 to the thickness of the base section 10 is configured to be between 10% and 40%. As will be described later, if the ratio of the thickness of the resin diffusion section 30 to the thickness of the base section 10 is less than 10%, there is a possibility of poor filling (insufficient filling) in the thin plate section 20, and if it exceeds 40%, there is a possibility of poor filling balance in the circumferential direction. Therefore, by setting the ratio of the thickness of the resin diffusion section 30 to the thickness of the base section 10 to 40%, it is possible to improve the filling balance in the circumferential direction while suppressing poor filling in the thin plate section 20.

[0039] Furthermore, in this embodiment, the ratio of the radial width of the resin injection section 40 to the thickness of the base section 10 is configured to be between 120% and 240%. As will be described later, if the ratio of the radial width of the resin injection section 40 to the thickness of the base section 10 is less than 120%, the circumferential filling balance may deteriorate. Also, if the ratio of the radial width of the resin injection section 40 to the thickness of the base section 10 exceeds 240%, there is a possibility of poor filling (insufficient filling) in the thin plate section 20. Therefore, by setting the ratio of the radial width of the resin injection section 40 to the thickness of the base section 10 to be between 120% and 240%, it is possible to improve the circumferential filling balance while suppressing poor filling in the thin plate section 20.

[0040] Furthermore, in this embodiment, the ratio of the radial width of the resin diffusion section 30 to the thickness of the base section 10 is configured to be between 60% and 100%. As will be described later, if the ratio of the radial width of the resin diffusion section 30 to the thickness of the base section 10 is less than 60%, the circumferential filling balance may deteriorate. Also, if the ratio of the radial width of the resin diffusion section 30 to the thickness of the base section 10 exceeds 100%, poor filling (insufficient filling) of the thin plate section 20 may occur. Therefore, by setting the ratio of the radial width of the resin diffusion section 30 to the thickness of the base section 10 to be between 60% and 100%, it is possible to improve the circumferential filling balance while suppressing poor filling of the thin plate section 20.

[0041] Furthermore, in this embodiment, one gate mark 41g is configured to be located at the same circumferential position as the reference blade 20s. By adopting this configuration, it is possible to make it less likely for insufficient filling to occur at the tip of the thin plate portion 20 (reference blade 20s).

[0042] Furthermore, this embodiment is a method for manufacturing a resin molded product 100 comprising a plate-shaped base portion 10 having an annular shape in plan view, a plurality of thin plate portions 20 extending from one annular surface of the base portion 10 along the thickness direction of the base portion 10, an annular resin injection portion 40 provided on the radially inward side of the base portion 10, and a resin diffusion portion 30 connecting the base portion 10 and the resin injection portion 40, and formed to be thinner in the thickness direction of the base portion 10 than either the base portion 10 or the resin injection portion 40, wherein the resin injection portion 4 in the molding die 300 The process includes the steps of: injecting molten resin into the first cavity 240 corresponding to 0 from a gate 240G leading to the first cavity 240; spreading the molten resin circumferentially within the first cavity 240; diffusing the molten resin within the first cavity 240 into the second cavity 230 corresponding to the resin diffusion section 30; and spreading the molten resin into the third cavity 210 corresponding to the base section 10 and the fourth cavity 220 corresponding to the thin plate section 20. By adopting this configuration, injecting molten resin from the gate 240G into the first cavity 240 forming the resin injection section 40 causes the molten resin to selectively diffuse circumferentially within the first cavity 240 before diffusing into the second cavity 230, thereby suppressing the circumferential dependence of the filling pressure. Therefore, the occurrence of filling defects due to filling balance can be suppressed, and products can be manufactured stably. Furthermore, even if the number of gates 240G is reduced, the resin diffuses sufficiently in the circumferential direction within the first cavity 240 before diffusing into the second cavity 230, thus suppressing the occurrence of filling defects caused by filling imbalance. In addition, the torsional rigidity of the resin molded product 100 can be adjusted by changing the radial and thickness dimensions of the resin injection section 40.

[0043] While this disclosure has been described based on various drawings and embodiments, it should be noted that those skilled in the art will find it easy to make various modifications and alterations based on this disclosure. Therefore, it should be noted that these modifications and alterations are included within the scope of the present invention. For example, the functions included in each component can be rearranged in a logically consistent manner, and multiple components can be combined into one or separated. It should be understood that these are also included within the scope of the present invention.

[0044] For example, in this embodiment, the resin molded product 100 is described as a fan element constituting a cross-flow fan, but the embodiment is not limited to this. The resin molded product 100 may be, for example, a blade member used for purposes other than a cross-flow fan, or it may be another member having a thin plate portion such as a brush. (Confirmation of the effect through resin flow analysis)

[0045] To confirm the effectiveness of the resin molded product 100 according to this embodiment, the quality of the filling balance was checked by resin flow analysis when the dimensions of the base portion 10, resin diffusion portion 30, and resin injection portion 40 shown in Figure 7 were changed. For both the "analysis example" with the resin diffusion portion 30 and resin injection portion 40 and the "comparative example" without the resin diffusion portion 30 and resin injection portion 40, analyses were performed for cases where a cold runner was used for the gate (analysis example number assigned "C") and cases where a hot runner was used for the gate (analysis example number assigned "H").

[0046] Here, the filling rate J[%] is defined as (W1 / Wf × 100) based on the weight (W1) of the first thin-walled plate section 20 (blade) to be filled with resin and the weight (Wf) when all thin-walled plate sections 20 (blades) are filled. This filling rate is used as the criterion for judging the filling balance, and ranks A to E are defined in Table 1. The temperature at the gate differs between cold runners and hot runners, with the cold runner having a lower temperature. Therefore, the resin flow rate is slower in cold runners compared to hot runners, resulting in a better filling balance. For this reason, the threshold values ​​for ranks A to E were set independently for cold runners and hot runners.

[0047] [Table 1]

[0048] Table 2 shows the conditions common to each analysis.

[0049] [Table 2]

[0050] Table 3 shows comparative examples and analysis examples when the number of gates is changed using a cold runner, and Table 3-1 shows comparative examples and analysis examples when the number of gates is changed using a hot runner.

[0051] [Table 3]

[0052] [Table 3-1]

[0053] In Table 3, in the comparative examples, the 12-point cold runner "Comparative Example #C12" and the 3-point cold runner "Comparative Example #C3" showed that the 12-point cold runner had a good filling balance due to the large number of gate points in the circumferential direction, resulting in an "A" rating, while the 3-point cold runner had a poor filling balance, resulting in a "D" rating. On the other hand, when using the present invention, the filling balance in the case of a 3-point gate improved to a better state than "C," and in particular, "Analysis Example #3-1C" showed a good filling balance, resulting in an "A" rating. Therefore, even in the case of a 3-point gate, the filling balance was found to be close to that of a 12-point gate.

[0054] Furthermore, in Table 3-1, while the "Comparative Example #H3" of the 3-point hot runner had poor filling balance and received an "E" rating, in all analysis examples of the 3-point hot runner using the present invention, the circumferential filling balance was improved compared to the comparative example, and in particular, "Analysis Example #3-1H" showed good filling balance and received an "A" rating. The results showed that the 3-point hot runner was close to that of the 12-point cold runner. This is thought to be because, in the analysis examples, the molten resin injected into the first cavity 240 is preferentially diffused in the circumferential direction first, so even with a relatively small number of gates, such as 3 gates, a good circumferential filling balance of the molten resin can be maintained.

[0055] In contrast, the comparative example does not have the resin diffusion section 30, so the molten resin injected from the three locations in the circumferential direction diffuses in the circumferential direction as well as in the radial direction at a similar rate. Therefore, the circumferential filling imbalance at the innermost circumference caused by the three-point gate is maintained at the base end of the thin plate section 20 at the outer circumference, so the filling balance in the thin plate section 20 is considered to deteriorate relatively.

[0056] In the comparative example, a tendency was found that the filling balance worsened more when using a 3-point hot runner than when using a 3-point cold runner. However, in the analysis examples, the difference in filling balance between the 3-point cold runner and the 3-point hot runner tended to decrease, and in particular, in "Analysis Example #3-1C" and "Analysis Example #3-1H", no significant difference in filling balance was observed between the 3-point cold runner and the 3-point hot runner. Using a 3-point hot runner is preferable because it reduces waste material from the runner and gate section, and from the results of this analysis, it was found that "Analysis Example #3-1H" is the best option for adopting a 3-point hot runner.

[0057] Next, for "Analysis Example #1-1C" and "Analysis Example #1-1H," we examined the change in filling balance of the cold runner "Analysis Example #C2" and hot runner "Analysis Example #H2" when the shape of the base part 10, resin diffusion part 30, and resin injection part 40 was kept the same and the gate was changed from a 3-point gate to a 2-point gate. In "Comparative Example #C2" of the 2-point cold runner, the filling balance was poor at "E" and molding was impossible, but both the cold runner "Analysis Example #C2" and hot runner "Analysis Example #H2" improved to "C" or better. When insufficient filling occurs at the tip of the thin plate part 20, there is a tendency for insufficient filling to occur at the reference blade 20s (see Figure 1). Therefore, by positioning one of the two gates 240G (i.e., gate mark 41g) at approximately the same circumferential position as the reference blade 20s, it is considered possible to create a 2-point hot runner without causing insufficient filling at the tip of the thin plate part 20.

[0058] By using hot runners, waste runners are eliminated, thus reducing running costs and improving product yield. Furthermore, the molding cycle time is shortened by eliminating waiting times for runner solidification and the need to remove waste runners, thus improving productivity. The number of gate points can also be reduced to three or fewer, thereby lowering mold manufacturing costs.

[0059] Furthermore, even when the number of gate points is three or more, it is believed that insufficient filling of the tip of the thin plate portion 20 can be suppressed by positioning one gate 240G at approximately the same circumferential position as the reference blade 20s. (Optimization of shape through resin flow analysis)

[0060] Next, the thickness t of the base portion 10 was fixed at 2.5 [mm], and the other dimensions of the resin diffusion portion 30 and the resin injection portion 40 were optimized. (Optimization of the thickness a of the resin diffusion section 30)

[0061] First, the effect of changing the thickness a of the resin diffusion section 30 in five different ways on the filling balance was analyzed, and the thickness a was optimized. The analysis conditions and results are shown in Table 4 below.

[0062] [Table 4]

[0063] In Table 4, the parameter a that was varied was the thickness of the resin diffusion section 30, and was varied in five steps: a: 0.4, 0.5, 0.6, 0.8, and 1.0 [mm]. The ratio a / t of the thickness a of the resin diffusion section 30 to the thickness t: 2.5 [mm] of the base section 10 was 16%, 20%, 24%, 32%, and 40%, respectively.

[0064] As shown in Table 4, in the range of a:0.4 to 1.0 [mm] (ratio a / t of the thickness of the resin diffusion part 30 to the thickness of the base part 10: 16% to 40%), the filling balance was good when a:0.4 to 0.8, and particularly good when a:0.6 to 0.8. If the ratio a / t of the thickness of the resin diffusion part 30 to the thickness of the base part 10 is less than 10%, there is a possibility of poor filling (insufficient filling) in the thin plate part 20, and if it exceeds 40%, there is a possibility of poor filling balance in the circumferential direction. Therefore, it is preferable to set the ratio a / t of the thickness a of the resin diffusion part 30 to the thickness t of the base part 10 in the range of 10% to 40%, more preferably 16% to 32%, and most preferably 24% to 32%. With this configuration, it is possible to improve the circumferential filling balance while suppressing poor filling in the thin plate part 20. (Optimization of the volume of the resin injection section 40)

[0065] Next, the effect of changing the volume of the resin injection section 40 on the filling balance was analyzed, and the volume of the resin injection section 40 was optimized. The analysis conditions and results when the thickness b of the resin injection section 40 was changed in three ways are shown in Table 5, the analysis conditions and results when the radius Φi in Figure 7 was fixed and the width c of the resin injection section 40 was changed in four ways are shown in Table 5-1 below, and the analysis conditions and results when the radial width of the base section 10 was fixed and the width c of the resin injection section 40 was changed in three ways are shown in Table 5-2 below.

[0066] [Table 5]

[0067] [Table 5-1]

[0068] [Table 5-2]

[0069] As shown in Table 5, no improvement was observed even when the thickness b of the resin injection section was changed.

[0070] As shown in Table 5-1, when the radius Φi in Figure 7 is fixed and the width c of the resin injection section 40 is changed in four stages to 3.0, 4.0, 5.0, and 6.0 [mm] (increasing the width c on the outer circumference shortens the radial width of the base), the filling balance was "A" when the width c was 4.0, 5.0, and 6.0 [mm], showing a significant improvement.

[0071] Furthermore, even when the radial width of the base portion is fixed and the width c of the resin injection portion 40 is changed (when the width c is increased on the inner circumference side, the radius Φi becomes shorter), the filling balance was significantly improved to "A" when the width c was 4.0, 5.0, and 6.0 [mm]. This improvement was even greater than the filling balance when the radius Φi was fixed and the width c of the resin injection portion 40 was changed. If the width c is 6.0 [mm] or more, the filling balance in the circumferential direction may deteriorate. Therefore, it is considered that the optimal width c is between 4.0 and 6.0 [mm]. The ratio of the radial width c of the resin injection portion 40 to the thickness t of the base portion 10 (c / t) is preferably 120% to 240%, and more preferably 160% to 240%. (Optimization of the radial width L of the resin diffusion section 30)

[0072] Next, the effect of varying the radial width L of the resin diffusion section 30 in three ways on the filling balance was analyzed, and the radial width L of the resin diffusion section 30 was optimized. The analysis conditions and results are shown in Table 6 below. Similarly, when the thickness b of the resin injection section 40 is 4.5 [mm], the analysis results of the filling balance when varying the radial width L of the resin diffusion section 30 in three ways are shown in Table 6-1.

[0073] [Table 6]

[0074] [Table 6-1]

[0075] The ratio (L / t) of the radial width L of the resin diffusion section 30 to the thickness t of the base section 10 is preferably 60% or more, regardless of whether the thickness b of the resin injection section 40 is 2.5 or 4.5 [mm]. It was found that the filling balance is significantly improved when the ratio is around 80% (when L=2 [mm] in Tables 6 and 6-1). On the other hand, if the ratio (L / t) exceeds 100%, there is a possibility of poor filling (insufficient filling) at the tip of the thin plate section 20, so it is preferable that the ratio is between 60% and 100%. (Optimization of the corners of the resin diffusion section 30)

[0076] Next, we analyzed the effect on the filling balance when chamfers 35 were added to two corners on the base (outer circumference) side of the resin diffusion section 30 (see Figure 8A) and when chamfers 36 were added to two corners on the resin injection section (inner circumference) side (see Figure 8B). The analysis conditions and results are shown in Table 7 below.

[0077] [Table 7]

[0078] As shown in Table 7, providing a C-surface or R-surface on the radially inward side (see Figure 8B) improved the filling balance. This is likely because providing the C-surface 36C or R-surface 36R reduces the flow resistance when molten resin flows into the corners, making it easier for the molten resin to spread circumferentially within the resin injection section 40. On the other hand, as shown in Figure 8A, providing a C-surface 35C or R-surface 35R on the radially outward side makes it easier for the molten resin to diffuse from the resin injection section 40 towards the resin diffusion section 30, potentially worsening the filling balance.

[0079] Furthermore, providing an R-surface 36R at the inner circumference side corner of the resin diffusion section 30 tends to result in a slightly better filling balance than providing a C-surface 36C. [Industrial applicability]

[0080] The present invention provides a resin molded product 100 and a method for manufacturing the resin molded product 100 that can improve the balance of molten resin filling between multiple thin plate portions 20. [Explanation of Symbols]

[0081] 10 Base 10a Insertion groove 10as reference groove 13a Insertion groove 10b Chamfered section 20 Thin plate section 20s standard feather 21 Thin plate section 30 Resin diffusion section 35C C side 35R R side 36C C side 36R R side 40 Resin injection section 41 Proximal side 41g gate marks 100 Resin molded products 110 Element with shaft 130 Disc section 200 assembly 210 Third Cavity 220 4th Cavity 230 Second Cavity 240 First Cavity 240G Gate 300 molding dies h Fitting hole O center axis S-shaft

Claims

1. A plate-shaped base portion having an annular shape in plan view, Multiple thin plate portions extending from one annular surface of the base portion along the thickness direction of the base portion, An annular resin injection section having a gate mark is provided on the radially inward side of the base portion, A resin diffusion portion is formed to connect the base portion and the resin injection portion, and is thinner in the thickness direction of the base portion than either the base portion or the resin injection portion. They are formed as a single unit, The resin molded product is characterized in that the surface having the gate mark in the annular resin injection portion is the surface exposed on the side opposite to the thin plate portion in the thickness direction of the base portion.

2. The resin molded product according to claim 1, wherein the gate marks are provided at multiple locations in the circumferential direction at equal intervals.

3. The resin molded article according to claim 1 or 2, wherein the ratio of the thickness of the resin diffusion portion to the thickness of the base portion is 10% or more and 40% or less.

4. The resin molded article according to claim 1 or 2, wherein the ratio of the radial width of the resin injection portion to the thickness of the base portion is 120% or more and 240% or less.

5. The resin molded article according to claim 1 or 2, wherein the ratio of the radial width of the resin diffusion portion to the thickness of the base portion is 60% or more and 100% or less.

6. The resin molded article according to claim 1 or 2, wherein one of the gate marks is located at the same circumferential position as the reference vane.

7. A plate-shaped base portion having an annular shape in plan view, Multiple thin plate portions extending from one annular surface of the base portion along the thickness direction of the base portion, An annular resin injection section is provided on the radially inward side of the base portion, A resin diffusion portion is formed to connect the base portion and the resin injection portion, and is thinner in the thickness direction of the base portion than either the base portion or the resin injection portion. A method for manufacturing a resin molded product comprising: The surface having the gate mark in the annular resin injection section is the surface exposed on the side opposite to the thin plate portion in the thickness direction of the base portion. The process involves injecting molten resin into a first cavity corresponding to the resin injection section within a molding die, from a gate leading to the first cavity, The steps include spreading molten resin in the circumferential direction of the first cavity, The steps include: diffusing the molten resin in the first cavity into the second cavity corresponding to the resin diffusion section; The steps include spreading molten resin into the third cavity corresponding to the base portion and into the fourth cavity corresponding to the thin plate portion. A method for manufacturing a resin molded product, characterized by including the following:

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