JP5641567B2 - Die for injection molding of carrier for planetary gear unit - Google Patents

Description

The present invention relates to an injection mold for a carrier for a planetary gear device used in a power transmission system of an automobile, an industrial machine or the like.

Generally, the planetary gear device changes rotation transmitted from a power source such as a motor into a rotation convenient for driving other driven devices.

10 and 11 show an example of such a planetary gear device 100. FIG. As shown in FIGS. 10 and 11, the planetary gear device 100 is provided inside the gear case 101.
An input-side sun gear 102 that rotates integrally with the input shaft 102 a, a plurality of planetary gears 103 that mesh with the input-side sun gear 102, and the planetary gear 103 are supported so that they can revolve around the input-side sun gear 102. A carrier 104 is accommodated. And carrier 104
Has the same number of support shafts 106 as the planetary gears 103 on one side surface 105 for rotatably supporting the planetary gears 103. The carrier 104 has an output-side sun gear 110 that meshes with another planetary gear 108 on the other side surface 107 and at the center of rotation of the carrier 104. The planetary gear 103 is rotatably supported by the support shaft 106 of the carrier 104.
Meshes with the input side sun gear 102 and meshes with an internal gear 111 formed on the inner peripheral surface of the gear case 101. Further, the other planetary gear 108 that meshes with the output-side sun gear 110 of the carrier 104 is a support shaft 11 of another carrier 113 that rotates integrally with the output shaft 112.
4 is also rotatably supported by the gear 4 and meshes with an internal gear 115 formed on the inner peripheral surface of the gear case 101 (see Patent Document 1).

In recent years, such a planetary gear device 100 has a gear case 101, an input side sun gear 102, a planetary gear 1, in order to improve the quietness of operation noise, reduce the overall weight, and reduce the product price.
In some cases, the component parts such as 03 and the carrier 104 are formed by plastic (injection molding) (see Patent Document 2).

FIG. 12 is a diagram schematically showing the structure of the injection mold 120 of the carrier 104. As shown in FIG. 12, the injection mold 120 includes a cavity 121 for forming the carrier 104 and a pinpoint gate 122 for injecting molten plastic into the cavity 121 ( (See FIG. 10). The cavity 121 includes a first cavity portion 123 for forming the disk-shaped carrier main body 116, a plurality of (the same number as the support shafts 106) second cavity portions 124 for forming the plurality of support shafts 106, and the output side sun. Gear 1
And a third cavity portion 125 for forming 10 (see FIG. 10). And
A pinpoint gate 122 opens at the center of the first cavity portion 123.

When the carrier 104 is injection molded with such an injection molding die 120, FIG.
As shown in (b), the planetary gear 103 is caused by a difference in shrinkage when the plastic is cooled.
The support shaft 106 that rotatably supports the shaft tends to fall toward the inner side (the rotation center 126 side of the carrier 104). In FIG. 13B, the regular (designed) support shaft 106 is indicated by a two-dot chain line, and the support shaft 106 that has fallen is indicated by a solid line.

When the inclination (θ, ε) toward the inside of the support shaft 106 of the carrier 104 becomes large, the distance between the rotation centers of the planetary gear 103 and the input-side sun gear 102 meshing with the planetary gear 103 becomes too short.
The teeth of the planetary gear 103 and the teeth of the input-side sun gear 102 are squeezed together (interference between the tooth tip and the bottom of the tooth) and noise is generated or smooth rotation transmission is impossible (FIGS. 10 and 10). 13).
Further, due to the galling of the teeth of the planetary gear 103 and the teeth of the input side sun gear 102, uneven wear occurs between the teeth of the planetary gear 103 and the teeth of the input side sun gear 102, and the durability of the planetary gear device 100 is improved. It will cause a decline. In FIG. 13B, θ is a tilt angle of the support shaft 106 inward in the radial direction, and the center line 109 of the support shaft 106 with respect to a virtual line 118 parallel to the rotation center line 117 of the carrier 104. And θ = 0 ° when the rotation center line 117 of the carrier 104 and the center line 109 of the support shaft 106 are parallel to each other. In FIG. 13B, ε represents the amount of displacement of the tip end of the support shaft 106 inward in the radial direction.

In order to solve such a problem, as shown in FIGS.
The support shaft 106 of the carrier 104 is inserted into the support hole 131 of the annular plate 130 manufactured separately from
The support shaft 10 of the carrier 104 is supported by the support hole 131 of the annular plate 130.
Application of a technique for correcting the tilting of No. 6 is conceivable (see Patent Document 3). This FIG.
The annular plate 130 shown in (a) to (b) is a long hole in which the support hole 131 extends in the circumferential direction, and after engaging the support shaft 106 before correction to the one end 131a side in the circumferential direction of the support hole 131, By rotating the support shaft 106 with respect to the carrier 104 until the support shaft 106 is positioned on the other end 131b side in the circumferential direction of the support hole 131, the support shaft 10 is provided on the other end 131b side in the circumferential direction of the support hole 131.
6 postures (fall down) can be corrected. 14 (a) to 14 (b), the parts corresponding to the components of the planetary gear device 100 of FIG. 10 include the planetary gear device 10 of FIG.
The same reference numerals as those of the component parts 0 are attached, and the description overlapping the description of the planetary gear device 100 of FIG. 10 is omitted.

Microfilm (see FIGS. 1 and 3) of Japanese Utility Model Application No. 01-103333 (Japanese Utility Model Application Publication No. 03-043148) Japanese Patent Laid-Open No. 11-132297 (refer to description of paragraph 0009) Japanese Unexamined Patent Publication No. 2009-287664 (see paragraph numbers 0006 to 0007, 0026 to 0028, FIG. 8, FIG. 11, and FIG. 12)

However, when the annular plate 130 manufactured separately from the carrier 104 is used to correct the inward tilt of the carrier 104 to the support shaft 106, the annular plate 13
It is necessary to newly secure an accommodation space of 0 in the gear case 101, and the planetary gear device 10
This causes a new problem that the size of the planetary gear device 100 is increased, the weight of the planetary gear device 100 is increased, and the product price of the planetary gear device 100 is increased.

Therefore, the present invention can suppress the falling of the support shaft of the carrier due to the injection molding so that a separate part (annular plate) for correcting the tilt of the support shaft of the carrier after the injection molding is unnecessary. An object of the present invention is to provide a mold for injection molding of a carrier for a planetary gear device.

As shown in FIGS. 1 to 9, the injection mold for the planetary gear carrier according to the invention of claim 1 includes: (1) a first cavity for forming a disc-shaped carrier body; 2) a second cavity portion that is the same number of support shafts as the planetary gears that rotatably support a plurality of planetary gears that mesh with the input-side sun gear, and that forms a support shaft that protrudes from one side surface of the carrier body; (3) a third cavity portion for projecting from the other side surface of the carrier body and forming an output-side sun gear concentrically with the center of rotation of the carrier body. A pinpoint gate for injecting molten plastic into the first cavity portion is opened at a position corresponding to the rotation center on the one side surface of the carrier body in the first cavity portion. doing. The opening portion of the second cavity portion is a flow of the molten plastic injected into the first cavity portion from the pinpoint gate, and the molten plastic flowing in the first cavity portion. It protrudes in a cylindrical shape in the first cavity portion so that the flow of air can be obstructed.

A carrier for injection molding of a carrier for a planetary gear device according to a second aspect of the invention is characterized by the shape of the opening portion of the second cavity portion of the first aspect of the invention. That is,
As shown in FIGS. 7 to 9, the projecting height of the opening portion of the second cavity portion gradually decreases as the distance from the center of the opening of the pinpoint gate increases.

The carrier for a planetary gear device that is injection-molded by using the injection mold according to the present invention can suppress the tilting of the support shaft to such an extent that a separate part for correcting the tilting of the support shaft is unnecessary. As a result, the carrier for the planetary gear device that is injection-molded using the injection mold according to the present invention invites an increase in the size of the planetary gear device, an increase in the weight of the planetary gear device accompanying an increase in the number of parts, There will be no increase in the product price of the planetary gear unit.

Fig.1 (a) is sectional drawing of the injection mold of the carrier for planetary gear apparatuses which concerns on 1st Embodiment of this invention, FIG.1 (b) is an expansion of the part shown by F1 of Fig.1 (a). FIG. It is sectional drawing cut | disconnected and shown along the A1-A1 line | wire of Fig.1 (a). It is a figure which shows the carrier for planetary gear apparatuses injection-molded with the metal mold | die for injection molding which concerns on 1st Embodiment of this invention. 3 (a) is a front view of the carrier, FIG. 3 (b) is a side view of the carrier, and FIG. 3 (c) is a cross-sectional view taken along line A2-A2 of FIG. 3 (a). FIG. FIG. 4A is a cross-sectional view of an injection mold for a planetary gear carrier according to a second embodiment of the present invention, and FIG. 4B is an enlarged view of a portion indicated by F2 in FIG. 4A. FIG. It is sectional drawing cut | disconnected and shown along the A3-A3 line | wire of Fig.4 (a). It is a figure which shows the carrier for planetary gear apparatuses injection-molded with the metal mold | die for injection molding which concerns on 2nd Embodiment of this invention. 6 (a) is a front view of the carrier, FIG. 6 (b) is a side view of the carrier, and FIG. 6 (c) is a cross-sectional view taken along line A4-A4 of FIG. 6 (a). FIG. Fig.7 (a) is sectional drawing of the injection mold of the carrier for planetary gear apparatuses which concerns on 3rd Embodiment of this invention, FIG.7 (b) is an expansion of the part shown by F3 of Fig.7 (a). FIG. It is sectional drawing cut | disconnected and shown along the A5-A5 line | wire of Fig.7 (a). It is a figure which shows the carrier for planetary gear apparatuses injection-molded with the metal mold | die for injection molding which concerns on 3rd Embodiment of this invention. 9 (a) is a front view of the carrier, FIG. 9 (b) is a side view of the carrier, and FIG. 9 (c) is a cross-sectional view taken along line A6-A6 of FIG. 9 (a). FIG. It is a longitudinal cross-sectional view of the planetary gear apparatus using the conventional carrier. It is sectional drawing cut | disconnected and shown along the A7-A7 line | wire of FIG. It is sectional drawing of the metal mold | die for injection molding used in order to carry out injection molding of the carrier for the conventional planetary gear apparatus. It is a figure which shows the deformation | transformation state (falling of a support shaft) of the support shaft after the injection molding of the carrier for the conventional planetary gear apparatus, FIG.13 (a) is a front view of a carrier, FIG.13 (b) is a carrier. It is a side view. FIG. 14 is a diagram showing an application example of the technique for correcting the tilt of the support shaft of the carrier shown in FIG. 13, FIG. 14 (a) is a view from the front side of the carrier, and FIG. 14 (b) is FIG. It is sectional drawing cut | disconnected and shown along the A8-A8 line | wire of ().

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a cross-sectional view showing an injection mold 2 of a planetary gear carrier 1 according to a first embodiment of the present invention. 2 is a cross-sectional view of the injection mold 2 cut along the line A1-A1 of FIG. FIG. 3 shows a plastic planetary gear carrier 1 that is injection molded by the injection mold 2 shown in FIGS. In addition,
The planetary gear device carrier 1 shown in FIG. 3 can be used in place of the conventional carrier 104 in the planetary gear device 100 of FIG. 10, and will be described with reference to FIG. 10 for convenience of explanation.

(Carrier for planetary gear device and injection mold thereof)
As shown in FIG. 3, a carrier 1 for a planetary gear device that is injection-molded by the injection-molding mold 2 shown in FIGS. 1 and 2 includes a disc-shaped carrier body 3 and one side surface 4 of the carrier body 3. And the output side sun gear 7 that protrudes from the other side surface 6 of the carrier body 3 (see FIG. 10).

Three support shafts 5 integral with the carrier body 3 are formed at equal intervals (at intervals of 120 °) in the circumferential direction of the circle 10 around the rotation center 8 of the carrier body 3. The bottom surface 12 of the round hole 11 formed on the side surface 4 side (a part of one side surface 4 of the carrier body 3)
Projecting substantially parallel to the rotation center line 13. An annular groove 14 is formed between the inner peripheral surface of the round hole 11 on the side surface 4 side of the carrier body 3 and the outer peripheral surface of the support shaft 5. The groove depth of the annular groove 14 is determined in consideration of the convenience in injection molding of the planetary gear device carrier 1 and the rigidity in the rotation direction of the planetary gear device carrier 1. Note that the support shaft 5 does not protrude parallel to the rotation center line 13 of the carrier body 3,
The reason why the support shaft 5 protrudes substantially parallel to the rotation center line 13 of the carrier body 3 is that the deformation of the support shaft 5 and the like due to a difference in shrinkage after injection molding (an error from the design value) is taken into account. is there.

The output side sun gear 7 integrated with the carrier body 3 is formed so that the center axis 15 is concentric with the rotation center line 13 of the carrier body 3. The output-side sun gear 7 has a bottomed hole 17 along the rotation center line 13 from the front end surface 16 along the rotation center line 13 to a position corresponding to the other side surface 6 of the carrier body 3. Is formed.

As shown in FIGS. 1 and 2, the injection molding die 2 of the planetary gear device carrier 1 is formed with a cavity 20 for injection molding the planetary gear device carrier 1 shown in FIG. The injection mold 2 is roughly divided into a fixed mold 21 and a movable mold 22, and the fixed mold 21 and the movable mold 22.
A first cavity portion 23 that is a disk-shaped recess for forming the carrier body 3 is formed on the mold matching surfaces 21p and 22p. In addition, the die-matching surfaces 21p of the fixed die 21 and the movable die 22;
22p is formed so as to coincide with the upper end edge 25 of the outer peripheral chamfer 24 on the side surface 4 side of the carrier body 3.

The fixed mold 21 (21a, 21b) is formed with a part of the first cavity portion 23 described above (a portion corresponding to the one side surface 4 side of the carrier body 3), and the planetary gear device carrier 1.
The second cavity portions 26 for forming the plurality of support shafts 5 are formed in the same number as the support shafts 5. The second cavity portion 26 forms a round bar-like support shaft 5, so that the first cavity portion 23 is formed.
It is a round hole with a bottom that opens at the bottom. The second cavity portion 26 is formed in the fixed mold 21 so as to be parallel to the center line 27 of the first cavity portion 23 corresponding to the rotation center line 13 of the carrier body 3. Moreover, the opening part 28 of this 2nd cavity part 26 protrudes cylindrically in the 1st cavity part 23, and narrows the space of the 1st cavity part 23 partially. Then, the opening portion 28 of the second cavity portion 26 protrudes into the first cavity portion 23 in a cylindrical shape, whereby the annular groove 14 shown in FIGS. 3A and 3C is formed, and the carrier The plate thickness from a part (bottom surface 12) of one side surface 4 of the main body 3 to the other side surface 6 is partially reduced. In addition, the fixed die 21 is open to the center 30 of the first cavity portion 23 corresponding to the rotation center 8 of the carrier body 3, and is in the first cavity portion 23 along the center line 27 of the first cavity portion 23. And molten plastic (polyacetal, polyamide,
A pinpoint gate 31 for injecting a plastic such as polyphenylene sulfide (PPS) or a plastic such as polyacetal, polyamide, or PPS mixed with reinforcing fibers such as carbon fibers is formed.

The movable die 22 is configured such that the cavity 20 can be opened to the outside by separating the die matching surface 22p from the state (the state shown in FIG. 1A) in which the die matching surface 22p is in close contact with the die matching surface 21p. The movable die 22 has a remaining portion of the first cavity portion 23 (a first cavity formed in the fixed die 21) which is a disk-like recess for forming most of the carrier body 3 on the die matching surface 22p side. The remaining part of the first cavity part 23 excluding a part of the part 23) is formed. The movable mold 22 is a third cavity portion 3 that is a substantially cylindrical recess for forming the output-side sun gear 7.
2 is formed to open to the first cavity portion 23. The movable mold 22 is positioned such that the shaft mold portion 33 corresponding to the hollow hole 17 of the output side sun gear 7 is surrounded by the third cavity portion 32, and the tip surface 33 a of the shaft mold portion 33 is the first cavity. It is formed so as to be located on the same plane as the side surface 34 of the portion 23 (the portion corresponding to the other side surface 6 of the carrier body 3). In addition, the movable die 22 is separated from the fixed die 21 (after the mold is opened), and the injection molded product (the planetary gear device carrier 1) remaining in the first cavity portion 23 and the third cavity portion 32 is the first. An eject pin 35 for taking out from the cavity portion 23 and the third cavity portion 32 is provided.

The fixed mold 21 and the movable mold 22 are divided into a plurality of blocks (21 according to the shape of the injection molded product.
a, 21b, 22a, 22b...

(Injection molding of carrier for planetary gear unit)
In order to injection-mold the carrier 1 for a planetary gear device, as shown in FIG. 1, the mold-clamping surface 21p of the fixed mold 21 and the mold-matching surface 22p of the movable mold 22 are in close contact with each other, and a pinpoint gate A molten plastic is injected from 31 into the first cavity portion 23.

The molten plastic injected into the first cavity portion 23 is the first cavity portion 2.
After flowing into the third cavity portion 32 from the inside of 3 and filling the third cavity portion 32, the first
The cavity portion 23 flows from the radially inner side toward the radially outer side. At this time, the flow of the molten plastic flowing from the radially inner side toward the radially outer side in the first cavity portion 23 is cylindrically projected in the first cavity portion 23. The second cavity portion 26 is obstructed by the opening portion 28 and uniformly filled around the opening portion 28 of the second cavity portion 26, and then flows into the second cavity portion 26 almost simultaneously from the periphery of the opening portion 28. The molten plastic flow flowing from the first cavity portion 23 into the second cavity portion 26 is squeezed and arranged by the opening portion 28 of the second cavity portion 26.

(Effects obtained by the injection mold of this embodiment)
The planetary gear device carrier 1 injection-molded using the injection-molding mold 2 of the present embodiment is
The tilt of the support shaft 5 is significantly smaller than the tilt of the support shaft 106 of the carrier 104 (see FIG. 13) injection-molded using the conventional injection mold 120 (see FIG. 12) (see FIG. 12). (See Table 1). As a result, the planetary gear device carrier 1 injection-molded using the injection-molding die 2 of the present embodiment is a separate component (annular plate 130) for correcting the tilt of the support shaft 106 of the conventional example shown in FIG. ) Is not required, leading to an increase in the size of the planetary gear device 100, an increase in the weight of the planetary gear device 100 due to an increase in the number of parts, and an increase in the product price of the planetary gear device 100.

Table 1 shows the tilting of the support shaft 5 of the carrier for planetary gear device 1 (the carrier of the present invention) 1 injection-molded using the injection-molding die 2 of the present embodiment, and the injection-molding die 120 of the conventional example. Is shown in comparison with the tilting of the support shaft 106 of the carrier 104 (conventional example carrier) that has been injection-molded using (see FIGS. 1, 3, 12, and 13). In Table 1, the carrier (1) of the present invention and the carrier 104 of the conventional example are injection-molded with PPS containing fibers. An injection mold 2 in which the carrier of the present invention (planetary gear device carrier 1) is injection-molded is a width dimension t1 along the center line of the first cavity 23 in FIG. T2 / t1 was set to 1/3 (however, t1 = 3 mm) where t2 is the protrusion height.
In FIG. 1, when the outer diameter of the opening is d2, and the inner diameter of the second cavity portion 26 is d1, d1 / d2 is 3/5 (d2 = 3 mm).

In addition, as a fiber mixed in PPS, fibrous reinforcements, such as a whisker, glass fiber, and an aramid fiber, are used. In addition, t2 / t1 can obtain substantially the same effect (result of Table 1) in the range of 1/3 to 1/2. Moreover, d1 / d2 can obtain substantially the same effect (result of Table 1) in the range of 1/2 to 3/4.

[Second Embodiment]
FIG. 4 is a cross-sectional view showing an injection mold 2 of the planetary gear carrier 1 according to the second embodiment of the present invention. FIG. 5 is a sectional view of the injection mold 2 cut along the line A3-A3 in FIG. FIG. 6 shows a plastic planetary gear device carrier 1 injection-molded by the injection-molding mold 2 shown in FIGS. In addition,
The planetary gear device carrier 1 shown in FIG. 6 can be used in place of the conventional carrier 104 in the planetary gear device 100 of FIG. 10, similarly to the planetary gear device carrier 1 shown in FIG. 3. is there. Further, the injection mold 2 according to the present embodiment is the same as the injection mold 2 according to the first embodiment except for the shape of the second cavity portion 26. Further, the planetary gear device carrier 1 injection molded by the injection mold 2 according to the present embodiment is
Except for the shape of the support shaft 5, other configurations are the same as those of the carrier 1 for a planetary gear device that is injection-molded by the injection mold 2 according to the first embodiment. Therefore, in the injection mold 2 according to the present embodiment, the same components as those of the injection mold 2 according to the first embodiment are denoted by the same reference numerals, and the description overlapping the description in the first embodiment. Is omitted. Further, the planetary gear device carrier 1 injection-molded with the injection mold 2 according to the present embodiment includes the planetary gear device carrier 1 injection-molded with the injection mold 2 according to the first embodiment. The same components are assigned the same reference numerals,
A description overlapping with the description in the first embodiment is omitted.

That is, the injection molding die 2 according to the present embodiment has a round bar shape extending along the center line 36 of the second cavity portion 26 in order to form the support shaft 5 of the carrier 1 for a planetary gear device in a hollow cylindrical shape. The meat removal pin 37 is installed integrally with the fixed mold 21. The meat removal pin 37 is formed in such a length that its front end surface is located on the same plane as the front end surface of the opening portion 28 of the second cavity portion 26. The meat removal pin 37 is integrated with the fixed mold 21 by press-fitting or screwing a metal rod formed separately from the fixed mold 21 into the fixed mold 21. And in FIG.
When the diameter of the meat removal pin 37 is d0, d0 / d1 is set to 1/3 to 1/2, and d1 / d2 is set to 1/2 to 3/4.

In the planetary gear device carrier 1 injection-molded by the injection molding die 2 according to this embodiment, the support shaft 5 is tilted by the support shaft 5 of the planetary gear device carrier 1 according to the first embodiment. It can be kept as small as falling (see Table 1).

In addition, in this embodiment, although the front end surface of the thinning pin 37 illustrated the aspect located in the same plane as the front end surface of the opening part 28 of the 2nd cavity part 26, it is not restricted to this, The distal end surface may protrude about (1/3) · t1 from the distal end surface of the opening portion 28 of the second cavity portion 26, and the distal end surface of the lightening pin 37 is the opening portion 28 of the second cavity portion 26. It may be retracted by about (1/3) · t1 from the front end face of

[Third Embodiment]
FIG. 7 is a sectional view showing an injection mold 2 of the planetary gear device carrier 1 according to the third embodiment of the present invention. 8 is a cross-sectional view of the injection mold 2 cut along the line A5-A5 in FIG. FIG. 9 shows a plastic planetary gear device carrier 1 injection-molded by the injection-molding mold 2 shown in FIGS. In addition,
The planetary gear device carrier 1 shown in FIG. 9 can be used in place of the conventional carrier 104 in the planetary gear device 100 of FIG. 10, similarly to the planetary gear device carrier 1 shown in FIG. 3. is there. Further, the injection mold 2 according to the present embodiment is the same as the injection mold 2 according to the first embodiment except for the shape of the opening portion 28 of the second cavity portion 26. Further, the planetary gear device carrier 1 injection molded by the injection molding die 2 according to the present embodiment has the other configuration except for the shape of the annular groove 14, and the other configuration is the injection molding die according to the first embodiment. It is the same as the planetary gear carrier 1 that is injection molded by the mold 2. Therefore, in the injection mold 2 according to the present embodiment, the same components as those of the injection mold 2 according to the first embodiment are denoted by the same reference numerals, and the description overlapping the description in the first embodiment. Is omitted. Further, the planetary gear device carrier 1 injection-molded with the injection mold 2 according to the present embodiment includes the planetary gear device carrier 1 injection-molded with the injection mold 2 according to the first embodiment. The same reference numerals are given to the same components, and the description overlapping the description in the first embodiment is omitted.

That is, the injection mold 2 according to the present embodiment has the opening portion 2 of the second cavity portion 26.
8 is formed so that the protrusion height gradually decreases as the distance from the center of the opening of the pinpoint gate 31 (the center line 27 of the first cavity portion 23) increases. As a result, the planetary gear device carrier 1 injection-molded by the injection-molding die 2 according to the present embodiment has the groove depth of the annular groove 14 formed around the support shaft 5 as the carrier body 3. As the distance from the rotation center line 13 increases, the depth becomes shallower.

In such an injection mold 2 according to this embodiment, the flow of the molten plastic flowing in the first cavity portion 23 from the radially inner side toward the radially outer side is the second.
Of the opening portion 28 of the cavity portion 26, the portion that is the closest to the pinpoint gate 31 is squeezed the most, and as the distance from the pinpoint gate 31 is decreased, the ratio of the opening portion 28 of the second cavity portion 26 is reduced. As a result, a time shift in which the molten plastic is filled around the opening portion 28 of the second cavity portion 26 is reduced, and the molten plastic is transferred from the first cavity portion 23 into the second cavity portion 26. It is possible to suppress the deviation of the inflow timing to be smaller than that of the injection mold 2 according to the first embodiment.

In the planetary gear device carrier 1 injection-molded by the injection molding die 2 according to this embodiment, the support shaft 5 is tilted by the support shaft 5 of the planetary gear device carrier 1 according to the first embodiment. It can be kept as small as falling (see Table 1).

1 ... Carrier for planetary gear unit 2 ... Mold for injection molding 3 ... Carrier body 4 ...
One side surface, 5... Support shaft, 6... The other side surface, 7... Output side sun gear, 8... Rotation center, 23. Opening part, 31 ...
Pinpoint gate, 32 ... 3rd cavity, 102 ... Sun gear on input side, 103 ...
... Planetary gear

Claims (2)

A first cavity for forming a disk-shaped carrier body;
A second cavity portion that forms the same number of support shafts as the planetary gears that rotatably support a plurality of planetary gears that mesh with the input-side sun gear and that protrudes from one side surface of the carrier body;
A third cavity for projecting from the other side of the carrier body and forming an output-side sun gear concentrically with the center of rotation of the carrier body;
A injection molding die carrier planetary gear unit having,
A pinpoint gate for injecting molten plastic into the first cavity portion is opened at a position corresponding to the rotation center of the one side surface of the carrier body in the first cavity portion,
The opening part of the second cavity part is a flow of the molten plastic injected into the first cavity part from the pinpoint gate, and the flow of the molten plastic flowing in the first cavity part Projecting in a cylindrical shape in the first cavity so that it can be disturbed,
Injection molding mold carrier planetary gear unit, characterized in that. The projecting height of the opening portion of the second cavity portion gradually decreases as the distance from the center of the opening of the pinpoint gate increases.
The mold for injection molding of the carrier for a planetary gear device according to claim 1.

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