JP6895547B2 - Resin molded products and molding methods for resin molded products - Google Patents

Description

The present invention relates to a resin molded product and a method for molding a resin molded product.

Conventionally, it is known that a cavity is provided inside a resin molded product and the molten resin is pressed with an inert gas in injection molding to suppress surface sink marks caused by shrinkage of the resin (for example, Patent Document 1). , Patent Document 2).
Further, it is known that an arc-shaped (so-called "corner R") rib is attached to a corner of a boss root by a gas assist method in order to increase the bending strength of a boss formed in a resin molded product (for example). , See Patent Document 1)

Japanese Unexamined Patent Publication No. 2008-911 Japanese Unexamined Patent Publication No. 10-58477

In Patent Document 1 and Patent Document 2, since a gas channel for passing gas is provided inside the resin molded product, the thickness of the resin becomes thicker, which contributes to weight reduction of the entire resin molded product and reduction of materials. Not done. Further, in order to apply gas pressure directly to the cavity surface of the molten resin, a sealing means is provided on the mating surface of the mold along the parting line so that the gas does not leak from the parting line of the resin molding mold. Is required.
An object of the present invention is to add a gas that does not require a sealing means for a resin molding die and can achieve both weight reduction and reinforcement by thinning the resin molded product without being restricted by a parting line. It is an object of the present invention to provide a resin molded product by pressure molding and a method for molding a resin molded product.

This specification includes all the contents of the Japanese patent application / Japanese Patent Application No. 2018-015910 filed on January 31, 2018.
According to the present invention, in a resin molded product formed by applying a pressurized gas to a resin in a resin molding die (22, 75), an elongated rib-shaped protrusion (10a, 52d,) is formed on a wall portion (10b, 52x). 56k) is integrally formed, and the elongated ribbed protrusions (10a, 52d, 56k) are arranged so as to surround a predetermined range of the wall portion (52x), and the elongated ribbed protrusions (10a, The wall thickness of the wall portion (10b, 52x) of the portion surrounded by the 52d, 56k) is formed to be thinner than the wall thickness of the other portion of the wall portion (10b, 52x). It is a feature.

In the above invention, the wall portion (52x) is integrated with reinforcing ribs (52m, 52q, 52r, 56a) having a larger amount of protrusion from the surface of the wall portion (52x) than the elongated rib-shaped protrusion (52d). A gradually changing wall thickness portion (52x) in which the wall thickness of the wall portion (52x) gradually changes between the elongated rib-shaped protrusion (52d) and the reinforcing rib (52m, 52q, 52r, 56a). 56d) may be provided.

Further, in the above invention, the elongated rib-shaped protrusion (52d) intersects the reinforcing rib (52q, 52r) at an angle of at least 20 degrees or more, and is more than the height of the reinforcing rib (52q, 52r). The height of the elongated ribbed protrusion (52d) may be low.
Further, in the above invention, the elongated rib-shaped protrusion (52d) may be continuously provided on the edge of the wall portion (52x).

Further, in the above invention, the wall portion (52x) is provided with an opening (56j), and the elongated rib-shaped protrusion (52d) is formed along the contour of the opening (56j) of the wall portion (52x). It may be provided continuously.

The present invention relates to a method for molding a resin molded product formed by applying a pressurized gas to a resin in a resin molding mold (22,75), wherein the wall portion (52x) of the resin molded product (10, 52) is formed. In addition, an elongated rib-shaped protrusion (10a, 52d, 56k) surrounding a predetermined range of the surface is formed, and the resin solidifies in the elongated rib-shaped protrusion (10a, 52d, 56k) faster than other parts. By sexual coagulation, the surrounding portion (10c, 56x) surrounded by the elongated rib-shaped protrusion portion (10a, 52d, 56k) is sealed so as to hold the pressurized gas.

In the above invention, the wall portion (52x) is integrated with reinforcing ribs (52m, 52q, 52r, 56a) having a larger amount of protrusion from the surface of the wall portion (52x) than the elongated rib-shaped protrusion (52d). A gradually changing wall thickness portion in which the wall thickness of the wall portion (52x) gradually changes between the elongated rib-shaped protrusion (52d) and the reinforcing rib (52m, 52q, 52r, 56a). (56d) may be provided.

Further, in the above invention, the elongated rib-shaped protrusion (52d) is intersected with the reinforcing rib (52q, 52r) at an angle of at least 20 degrees or more, and the height of the reinforcing rib (52q, 52r) is increased. The height of the elongated ribbed protrusion (52d) may be lowered.
Further, in the above invention, the elongated rib-shaped protrusion (52d) may be continuously provided on the edge of the wall portion (52x).

Further, in the above invention, the wall portion (52x) is provided with an opening (56j), and the elongated rib-shaped protrusion (52d) is continuously provided along the contour of the opening (56j) of the wall portion (52x). May be provided.

In the present invention, an elongated rib-shaped protrusion is integrally formed on the wall portion, and the elongated rib-shaped protrusion is arranged so as to surround a predetermined range of the wall portion and is surrounded by the elongated rib-shaped protrusion. Since the wall thickness of the wall portion is formed to be thinner than the wall thickness of other parts of the wall portion, the wall thickness of the resin molded product can be made thinner, and the weight of the resin molded product can be reduced. Further, since the rigidity of the resin molded product can be increased and reinforced by the elongated rib-shaped protrusions, the impact durability of the resin molded product can be improved. Further, since the elongated rib-shaped protrusion can be sealed so that the pressurized gas does not leak to the outside, the resin molding die does not require a dedicated sealing means and is not restricted by the parting line. It is possible to manufacture a resin molded product reinforced with a thin wall.

In the above invention, the wall portion is integrally provided with a reinforcing rib having a larger amount of protrusion from the surface of the wall portion than the elongated rib-shaped protrusion portion, and the wall thickness of the wall portion is provided between the elongated rib-shaped protrusion portion and the reinforcing rib. Since a gradually changing wall thickness portion is provided, a portion requiring rigidity and a portion not requiring so much rigidity can be appropriately arranged in the wall portion.

Further, in the above invention, the elongated rib-shaped protrusions intersect with the reinforcing ribs at an angle of at least 20 degrees or more, and the height of the elongated rib-shaped protrusions is lower than the height of the reinforcing ribs. It is possible to suppress stress concentration at the intersection of the protrusion and the reinforcing rib, and prevent the formation of an insertion groove at the intersection.
Further, in the above invention, since the elongated rib-shaped protrusions are continuously provided on the edge portion of the wall portion, the wall portion can be thinned to the vicinity of the edge portion of the resin molded product without impairing the appearance of the resin molded product. It will be possible.

Further, in the above invention, since the opening is provided in the wall portion and the elongated rib-shaped protrusions are continuously provided along the contour of the opening in the wall portion, the resin is not impaired in the appearance of the resin molded product. The wall portion can be thinned to the vicinity of the opening of the molded product.

In the present invention, an elongated rib-shaped protrusion surrounding a predetermined range on the surface of a wall portion of a resin molded product is formed, and the resin solidifies in the elongated rib-shaped protrusion faster than other parts by directional solidification. Since the surrounding portion surrounded by the rib-shaped protrusion is sealed so as to hold the pressurized gas, the thickness of the resin molded product can be reduced and the weight of the resin molded product can be reduced. Further, since the rigidity of the resin molded product can be increased and reinforced by the elongated rib-shaped protrusions, the impact durability of the resin molded product can be improved. In addition, by sealing the elongated rib-shaped protrusions so that the pressurized gas does not leak to the outside, it is possible to manufacture the resin molded product reinforced with the above-mentioned thin wall without being restricted by the parting line of the resin molding die. ..

Further, in the above invention, the wall portion is integrally formed with a reinforcing rib having a larger amount of protrusion from the surface of the wall portion than the elongated rib-shaped protrusion portion, and the wall portion is formed between the elongated rib-shaped protrusion portion and the reinforcing rib. Since the gradually changing wall thickness portion in which the wall thickness of the wall portion gradually changes is provided, a portion requiring rigidity and a portion not requiring so much rigidity can be appropriately arranged in the wall portion.

Further, in the above invention, the elongated rib-shaped protrusions are crossed with respect to the reinforcing ribs at an angle of at least 20 degrees or more, and the height of the elongated rib-shaped protrusions is lower than the height of the reinforcing ribs. It is possible to suppress stress concentration at the portion where the shaped protrusion and the reinforcing rib intersect, and it is possible to prevent the formation of an insertion groove at the intersecting portion.
Further, in the above invention, since the elongated rib-shaped protrusions are continuously provided on the edge of the wall, the wall can be thinned to the vicinity of the edge of the resin molded product without impairing the appearance of the resin molded product. It will be possible.

Further, in the above invention, since the opening is provided in the wall portion and the elongated rib-shaped protrusions are continuously provided along the contour of the opening in the wall portion, the resin molded product is molded without impairing the appearance. The wall can be thinned to the vicinity of the opening of the product.

FIG. 1 is an action diagram showing the principle of the resin molded product and the molding method of the resin molded product according to the present invention. FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is a perspective view showing a motorcycle. FIG. 4 is a perspective view showing the front portion of the vehicle body of the motorcycle. FIG. 5 is a perspective view showing the back surface of the front cover. FIG. 6 is a front view showing the back surface of the front cover. FIG. 7 is a perspective view showing a part A of FIG. FIG. 8 is a sectional view taken along line VIII-VIII of FIG. FIG. 9 is an enlarged view showing a portion B of FIG. FIG. 10 is a cross-sectional view taken along line XX of FIG. FIG. 11 is a perspective view including a cross section taken along line XI-XI of FIG. FIG. 12 is a perspective view of the core mold of the resin molding mold as viewed from the cavity mold side. FIG. 13 is a cross-sectional view taken along the line XIII-XIII of FIG. FIG. 14 is a perspective view showing a portion C in FIG. FIG. 15 is a perspective view including a cross section taken along line XV-XV of FIG. FIG. 16 is a perspective view showing a portion D in FIG. FIG. 17 is a cross-sectional view taken along the line XVII-XVII of FIG. FIG. 18 is a perspective view showing the lower part of the front cover. FIG. 19 is a perspective view showing the lower part of the front cover from the back surface side. FIG. 20 is a front view showing a part of the front surface of the inclined core. FIG. 21 is a cross-sectional view taken along the line XXI-XXI of FIG. FIG. 22 is a perspective view showing the opening of the rear bending wall portion of the front cover and its surroundings.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is an operation diagram showing the principle of the resin molded product 10 and the molding method of the resin molded product 10 according to the present invention, and FIG. 2 is an enlarged view of a main part of FIG.
As shown in FIG. 1, the injection molding apparatus 20 includes an injection molding machine 21 and a resin molding die 22 connected to the injection molding machine 21.
The injection molding machine 21 includes a cylinder 23, in which the resin charged inside is heated and melted, and the melted resin (molten resin 38) is further provided in a nozzle 23a provided at the tip of the cylinder 23. Is injected into the resin molding mold 22.
The resin molding die 22 includes a fixed mold 25 connected to the injection molding machine 21 and a movable mold 26 slidably provided on the fixed mold 25. The fixed mold 25 and the movable mold 26 are aligned by a parting line 27, and the fixed mold 25 and the movable mold 26 form a cavity 28 that forms the resin molded product 10.

The fixed mold 25 includes a passage 25a through which the molten resin 38 passes. One end of the passage 25a is connected to the nozzle 23a of the injection molding machine 21, and the other end is connected to the cavity 28.
The movable mold 26 includes a recess 31 forming the cavity 28 and a gas channel 32 communicating with the recess 31.
The concave portion 31 includes a concave groove 31a formed continuously and endlessly on the peripheral edge portion. When the resin molded product 10 is formed, the concave groove 31a forms a gas seal rib 10a as an elongated rib-shaped protrusion, and the concave portion 31 forms a plate-shaped wall portion 10b including the gas seal rib 10a.
The gas channel 32 includes a main passage 34 connected to an external gas supply source and a plurality of sub-passages 35 formed in the main passage 34, and the tip of the sub-passage 35 communicates with the recess 31.

Next, the operation of the injection molding apparatus 20 will be described.
In FIG. 1, first, the molten resin 38 in the cylinder 23 is injected into the resin molding die 22 from the nozzle 23a. The molten resin 38 flows into the cavity 28 through the passage 25a. Of the molten resin 38 that has flowed into the cavity 28, the molten resin 38 in the concave groove 31a solidifies faster than the molten resin 38 in other portions due to directional solidification.
At this time, as shown by the arrow in FIG. 2, nitrogen gas, for example, nitrogen gas, for example, is compressed to a predetermined pressure from the gas channel 32 between the bottom surface 31b of the recess 31 and the molten resin 38 in the cavity 28. Inject under pressure.

As a result, the gas pressure acts on the non-solidified molten resin 38 in the cavity 28, and the molten resin 38 is pressed against the cavity inner surface 25b of the fixed mold 25. At this time, the gas seal rib 10a formed by solidifying in the concave groove 31a becomes a sealing portion, and the injected nitrogen gas leaks from the cavity 28 to the outside of the resin molding die 22 via the parting line 27. Can be prevented. As a result, it is not necessary to specially provide a sealing member on the resin molding die 22.
By continuing the action of gas pressure on the unsolidified molten resin 38, the molten resin 38 is solidified in the surrounding portion 10c surrounded by the annular gas seal rib 10a in the wall portion 10b, which is a resin molded product. The wall thickness T of 10 can be reduced. As a result, the weight of the resin molded product 10 can be reduced. Further, the rigidity of the resin molded product 10 can be increased by the gas seal rib 10a.

Next, an example of applying the resin molded product 10 and the molding method of the resin molded product 10 to the motorcycle 40 will be described. In the following description, the directions such as front / rear / left / right and up / down are the same as the directions with respect to the vehicle body unless otherwise specified. Further, the reference numerals FR shown in each figure indicate the front of the vehicle body, the reference numerals UP indicate the upper part of the vehicle body, and the reference numerals LH indicate the left side of the vehicle body.
FIG. 3 is a perspective view showing the motorcycle 40, and FIG. 4 is a perspective view showing the vehicle body front portion 44 of the motorcycle 40.
As shown in FIG. 3, the motorcycle 40 is a scooter type vehicle. The motorcycle 40 is a vehicle body front portion 44 provided with a steering wheel 42 for steering the front wheels 41 and the front wheels 41, and a vehicle body rear portion 48 provided with a seat 46 located above the rear wheels 45 and the rear wheels 45 which are driving wheels. And a step floor 49 connecting the front portion 44 of the vehicle body and the rear portion 48 of the vehicle body.
Further, the vehicle body front portion 44 and the vehicle body rear portion 48 are covered with the vehicle body cover 51.

As shown in FIG. 4, the vehicle body cover 51 includes a front cover 52, a pair of left and right leg shields 53, and a steering wheel cover 54 at the front portion 44 of the vehicle body. In FIG. 4, the front cover 52 is in a state of being removed from the vehicle body.
The front cover 52 is rotated by the handle 42 and covers the front fork (not shown) that supports the front wheel 41 (see FIG. 3) from the front.
The left and right leg shields 53 extend diagonally rearward from the left and right edges of the front cover 52 and cover the legs of the driver seated on the seat 46 (see FIG. 3) from the front.
The handle cover 54 covers the central portion of the handle 42.

FIG. 5 is a perspective view showing the back surface of the front cover 52, showing the back surface 52a of the front cover 52. FIG. 6 is a front view showing the back surface 52a of the front cover 52. The gas seal rib 52d shown below is a single rib extending in a continuous annular shape, but in order to facilitate grasping the shape, the upper part, the lower part, and both side portions of the gas seal rib 52d are designated by reference numerals " 52d ”is attached.
As shown in FIGS. 5 and 6, the front cover 52 has a reinforcing rib aggregate 52b composed of a plurality of reinforcing ribs and a gas formed endlessly on the peripheral edge portion 52c or in the vicinity of the peripheral edge portion 52c on the back surface 52a. The seal rib 52d and the projecting portion aggregate 52e composed of a plurality of projecting portions are integrally provided. That is, in the front cover 52, the reinforcing rib assembly 52b, the gas seal rib 52d, and the projecting portion assembly 52e project from the back surface 52a of the wall portion 52x.
The projecting portion assembly 52e is composed of a pair of left and right clip nut mounting seats 52f, a pair of left and right undercut rib portions 52g, a plurality of clip fastening portions 52h, a plurality of seated fastening boss portions 52j, and a ribbed fastening boss portion 52k. ..

A clip nut is attached to the upper portion of the clip nut mounting seat 52f. The undercut rib portion 52g includes ribs that reinforce the left and right side portions of the upper portion of the front cover 52. The clip fastening portion 52h is locked to the left and right leg shields 53 (see FIG. 4) by a clip (not shown). The seated fastening boss portion 52j has a screw hole formed on the tip surface of the cylinder, and the ribbed fastening boss portion 52k is a portion in which a plurality of ribs are radially formed on the outer peripheral surface of the cylinder. It has a screw hole on the tip surface. The reinforcing plate (not shown) of the front cover 52 is fastened with screws to the seated fastening boss portion 52j and the ribbed fastening boss portion 52k.
As shown in FIG. 6, a plurality of inclined cores 61 to 67 for die cutting from a plurality of undercuts (including a pair of left and right undercut rib portions 52 g) provided on the back surface 52a of the front cover 52 are provided. It is arranged in a resin molding die 75 (see FIG. 12).

FIG. 7 is a perspective view showing a part A in FIG. 6, and FIG. 8 is a sectional view taken along line VIII-VIII of FIG.
As shown in FIG. 7, a gas seal rib 52d is formed along the edge reinforcing rib 52m inside the edge reinforcing rib 52m formed on the peripheral edge of the front cover 52.
Intermediate reinforcing ribs 52n and 52p extend from the edge reinforcing rib 52m toward the center of the front cover 52.
The gas seal rib 52d extends while intersecting with the intermediate reinforcing ribs 52n and 52p.

As shown in FIG. 8, assuming that the height of the gas seal rib 52d is H1 and the width of the upper end portion of the gas seal rib 52d is W1, the height H1 is lower than the height He of the edge reinforcing rib 52m (H1). <He), the width W1 is smaller than the width We of the edge reinforcing rib 52 m (W1 <We). Further, the wall thickness of the wall portion 52x between the gas seal rib 52d and the edge reinforcing rib 52m is Tg (see also FIG. 13), and the wall thickness of the wall portion 52x opposite to the edge reinforcing rib 52m of the gas seal rib 52d. Assuming the thickness Tf (see also FIG. 13), the width W1 is smaller than the wall thickness Tf (W1 <Tf).
As described above, since the gas seal rib 52d is an elongated rib having a smaller cross-sectional area than the edge reinforcing rib 52m, it is more likely to solidify in the molten resin state than other portions. Therefore, the above-mentioned wall thickness Tf can be formed to be thinner than the wall thickness Tg.

As described above, the wall thickness of the wall portion 52x between the gas seal rib 52d and the edge reinforcing rib 52m is set to a constant wall thickness Tg, but the thickness is not limited to this, and the edge reinforcement is performed from the gas seal rib 52d side. A gradual change wall thickness portion 56d (see FIG. 15) may be formed by having a predetermined distance L toward the rib 52m side and gradually increasing the thickness.

9 is an enlarged view showing a portion B of FIG. 6, and FIG. 10 is a cross-sectional view taken along line XX of FIG.
As shown in FIG. 9, two intermediate reinforcing ribs 52q and 52r extend from the edge reinforcing rib 52m toward the center side of the wall portion 52x. The two intermediate reinforcing ribs 52q and 52r intersect, and the gas seal rib 52d intersects these intermediate reinforcing ribs 52q and 52r.
The angle θ1 formed by the intermediate reinforcing rib 52q and the gas seal rib 52d and the angle θ2 formed by the intermediate reinforcing rib 52r and the gas seal rib 52d are 20 ° or more (θ1 ≧ 20 °, θ2 ≧ 20 °), respectively.

For example, when θ1 <20 ° and θ2 <20 °, the volume of the intersecting portion becomes large. Therefore, in the molding process of the intermediate reinforcing ribs 52q and 52r and the gas seal rib 52d, the pressure gas acts on the portion where the molten resin solidifies slowly at the intersection, so that an insertion groove (dent) is likely to be formed. The insertion groove is a portion that affects the strength, and it is necessary to prevent the formation of the insertion groove.
In the present embodiment, by setting θ1 ≧ 20 ° and θ2 ≧ 20 °, the volume of the intersecting portion becomes smaller, the solidification of the intersecting portion becomes faster, and the formation of the insertion groove can be prevented. Further, by setting θ1 ≧ 20 ° and θ2 ≧ 20 °, stress concentration at the intersection can be suppressed. Further, if the temperature is 20 ° or more, the durability due to the shape of the mold is also improved.
As shown in FIG. 10, the height of the intermediate reinforcing rib 52q from the back surface 52a is H2, and the width of the tip of the intermediate reinforcing rib 52q is W2. The height H2 is higher than the height H1 of the gas seal rib 52d shown in FIGS. 8 and 9. The width W2 is larger than the width W1 of the gas seal rib 52d shown in FIGS. 8 and 9.

As shown in FIGS. 8 to 10 above, the gas seal rib 52d intersects the intermediate reinforcing ribs 52q and 52r as reinforcing ribs at an angle of at least 20 degrees or more, and the intermediate reinforcing ribs 52q and 52r The height of the gas seal rib 52d is lower than the height.
According to this configuration, stress concentration at the intersection of the gas seal rib 52d and the intermediate reinforcing ribs 52q and 52r can be suppressed, and the formation of an insertion groove at the intersection can be prevented.

FIG. 11 is a perspective view including a cross section taken along line XI-XI of FIG.
On the back surface 52a of the wall portion 52x of the front cover 52, a honeycomb reinforcing portion 52t in which a plurality of honeycomb reinforcing ribs 52s protruding in a hexagonal shape are assembled is integrally formed.
The honeycomb reinforcing portion 52t is formed on the inner wall portion 52x of the predetermined honeycomb reinforcing rib 52s1 (which has the same shape as the honeycomb reinforcing rib 52s but has a different reference numeral for identification) by a resin molding die. A portion 52w (see also FIG. 13) is formed. Let Te be the wall thickness of the ultra-thin part 52w.
Further, a resin molding metal is formed on the inner wall portion 52x of the honeycomb reinforcing ribs 52s2 and 52s3 (which have the same shape as the honeycomb reinforcing ribs 52s but have different symbols for identification) adjacent to the honeycomb reinforcing ribs 52s1. Depending on the mold, it is formed to have the same wall thickness Te as the ultra-thin wall portion 52w. Assuming that the wall thicknesses of the medium and thin portions 52z and 52z are Tf, Te <Tf.

A gas channel slit 70 is formed in the core 78 (see FIG. 12) of the resin molding die 75 (see FIG. 13) forming the honeycomb reinforcing portion 52t. From the gas channel slit 70, the pressurized gas acts on the molten resin forming the ultra-thin wall portion 52w of the wall portion 52x surrounded by the honeycomb reinforcing ribs 52s1, 52s2, 52s3 .... Therefore, due to this pressurized gas, the ultra-thin portion 52w is made thinner than the wall thickness setting by the resin molding die.

FIG. 12 is a perspective view of the core mold 77 of the resin molding mold 75 as viewed from the back surface side. Here, in order to facilitate the distinction between the cavity type 76 and the core type 77, the cavity type 76 is represented by a broken line and the core type 77 is represented by a solid line for convenience. The shape of each part of the core mold 77 corresponds to the shape of each part of the front cover 52 shown in FIG. However, the core type 77 is described so as to be flipped horizontally with respect to the front cover 52 shown in FIG.
A plurality of resin molding dies 75 include a cavity mold 76 which is a fixed mold, a core mold 77 which is a movable mold, a core 78 forming a honeycomb reinforcing portion 52t (see FIG. 6), and inclined cores 61 to 67. Gas channel pin 79 and a plurality of ejector pins 80 are provided.
The core 78 and the inclined cores 61 to 67 for the honeycomb reinforcing portion 52t are arranged apart from the edge of the front cover 52 (see FIG. 6), and a plurality of gas channel slits 70 to 74 are arranged parallel to the core 78. (Here, 5) are provided.

When pressurized gas is added to the section surrounded by the gas seal rib 52d, a front cover in which a plurality of gas channel pins 79 and a plurality of gas channel slits 70 to 74 are workpieces on the core mold 77 of the resin molding mold 75. 52 (see FIG. 6) is appropriately arranged according to the shape.
In the present embodiment, the pressurized gas is supplied to the area partitioned by the plurality of honeycomb reinforcing ribs 52s formed by the core 78 through the gas channel slits 70 to 74 provided in the core 78.
The parts other than the honeycomb reinforcing portion 52t are partitioned by each reinforcing rib, but the discharge port of the gas channel pin 79 (see also FIG. 13) arranged at the tip of each reinforcing rib is located at the width of each reinforcing rib. Is also provided with a large opening to supply pressurized gas to multiple areas partitioned by each reinforcing rib. Further, depending on the portion of the front cover 52, the gas channel pin 79 may be provided directly toward the wall portion 52x.

FIG. 13 is a cross-sectional view taken along the line XIII-XIII of FIG.
The cavity type 76 and the core type 77 are matched by the parting line 81.
The cavity type 76 includes an injection gate 76a. The core type 77 includes a gas manifold 83 in which a main passage 83a for pressurized gas is formed, and a plurality of gas channel pins 79 extending from the main passage 83a of the gas manifold 83. A gas introduction path 77a for introducing a pressurized gas into the main passage 83a from the outside of the resin molding die 75 is formed in the main passage 83a of the gas manifold 83. The pressurized gas passes through the gas introduction path 77a and the main passage 83a, and further passes through a plurality of gas channel pins 79 and gas channel slits 70 to 74 (see FIG. 12) to each area inside the gas seal rib 52d. Be supplied.

Regarding the wall thickness of the wall portion 52x of the molded front cover 52, the ultra-thin wall portion 52w and the edge portion (gas seal rib) of the wall portion 52x are located at the center portion of the wall portion 52x (including a part of the honeycomb reinforcing portion 52t). A thick portion 52y is formed in a portion outside the 52d, and a medium-thin portion 52z is formed in a portion between the ultra-thin portion 52w and the edge portion of the wall portion 52x (including a part of the honeycomb reinforcing portion 52t). There is. Assuming that the wall thicknesses of the ultra-thin portion 52w, the medium-thin wall portion 52z, and the thick-walled portion 52y are Te, Tf, and Tg, the relationship between the respective wall thicknesses is Te <Tf <Tg.
As described above, in the present embodiment, the wall portion 52x is referred to as an ultra-thin zone E having an ultra-thin portion 52w, a medium-thin zone F having a medium-thin portion 52z, and a thick-walled zone G having a thick-walled portion 52y. The wall thickness is set in three levels of zones. The molding die for forming the wall thicknesses Te and Tf is set to be slightly thicker than the wall thicknesses Te and Tf in anticipation of molding by the pressurized gas, and the molten resin is injected, and the injection time is corresponding to that amount. It will be shortened.
As described above, the surrounding portion 56x inside the gas seal rib 52d in the wall portion 52x is formed thinner than the outside of the gas seal rib 52d in the wall portion 52x.

FIG. 14 is a perspective view showing a portion C in FIG. FIG. 15 is a perspective view including a cross section taken along line XV-XV of FIG.
As shown in FIGS. 14 and 15, the gas seal rib 52d and the reinforcing rib 56a arranged so as to be along the gas seal rib 52d and separated from the gas seal rib 52d are integrally formed on the wall portion 52x. There is.
A thin wall portion 56b is formed on the wall portion 52x surrounded by the gas seal rib 52d, and the wall portion 52x on the side away from the gas seal rib 52d from the reinforcing rib 56a has a wall thickness Tf of the thin wall portion 56b. A thick portion 56c having a thicker Tg than that of the thick portion 56c is formed.
As shown in FIG. 15, in the wall portion 52x, the wall portion 56z provided between the gas seal rib 52d and the reinforcing rib 56a has a thin wall portion 56y and a gradual change in wall thickness toward the thin wall portion 56y. A thick portion 56d is formed. The wall portion 56z constitutes a part of the wall portion 52x.
The thin portion 56y is a portion having a constant wall thickness formed so as to be separated from the gas seal rib 52d by a predetermined distance L. The wall thickness of the thin-walled portion 56y is the same as that of the thin-walled portion 56b or thicker than that of the thin-walled portion 56b. The wall thickness increases in a tapered cross section toward the 56a side.

The wall thickness of the edge portion of the gradually changing wall thickness portion 56d in contact with the thin wall portion 56y (the thinnest wall thickness in the gradually changing wall thickness portion 56d) is the same as that of the thin wall portion 56y, and the reinforcing rib 56a of the gradually changing wall thickness portion 56d is the same. The wall thickness of the edge portion in contact with the thick portion (the thickest wall thickness in the gradually changing wall thickness portion 56d) is the same as that of the thick wall portion 56c.

The gradually changing wall thickness portion 56d is formed between a portion separated from the gas seal rib 52d on the reinforcing rib 56a side by a predetermined distance L and the reinforcing rib 56a.
Since the wall thickness is thick in the vicinity of the gradually changing wall thickness portion 56d, particularly in the vicinity of the reinforcing rib 56a, in the molding process of the front cover 52, solidification is slower than in the vicinity of the gas seal rib 52d due to the directional solidification of the molten resin. Become. Therefore, when the vicinity of the reinforcing rib 56a of the gradually changing wall thickness portion 56d is pressed with a pressurized gas at the time of melting, the molten resin is sunk into the soft portion inside, and an insertion groove is formed on the surface of the molten resin. Therefore, the pressure of the pressurized gas is prevented from acting on the vicinity of the reinforcing rib 56a of the gradually changing wall thickness portion 56d by the gas seal rib 52d.

16 is a perspective view showing a portion D in FIG. 6, and FIG. 17 is a cross-sectional view taken along the line XVII-XVII of FIG.
As shown in FIG. 16, one ends of the two reinforcing ribs 56e and 56f are connected to the edge reinforcing ribs 52m of the front cover 52. Further, the reinforcing ribs 56g extend along the edge reinforcing ribs 52m so that one end is connected to one of the reinforcing ribs 56e and intersects the reinforcing ribs 56f.
The gas seal rib 52d bends along the edge reinforcing rib 52m and extends along the reinforcing rib 56e, and intersects the reinforcing rib 56g.
If it is difficult to provide the gas seal rib 52d inside the edge reinforcing rib 52m of the front cover 52, as shown in FIG. 17 and FIG. 22 described later, the rear bending having the edge reinforcing rib 52m and the undercut of the front cover 52. A gas seal rib 52d is integrally formed on the wall portion 56h.

As shown in FIGS. 16 and 17, the gas seal rib 52d is provided not only near the outer edge of the wall portion 52x of the front cover 52 along the outer edge, but also the edge reinforcing rib provided on the outer edge of the wall portion 52x. Since it can be provided 52 m above, the nitrogen gas seal portion can be arranged so as not to leak to the outside of the resin molding die 75 from the gap of the parting line 81 (see FIG. 13). As a result, not only can the special sealing member be omitted from the resin molding die 75, but also the wall thickness can be reduced over a wide range up to the vicinity of the outer peripheral edge of the front cover 52, so that the amount of resin material can be reduced, resulting in cost reduction and significant weight reduction. It can be converted.

Further, as shown in FIGS. 14 and 15, the wall portions 52x located at both end portions of the front cover 52 are provided with reinforcing ribs 56a having a larger amount of protrusion from the surface of the wall portion 52x than the gas seal rib 52d. By providing a gradually changing wall thickness portion 56d in which the wall thickness of the wall portion 56z gradually changes between the gas seal rib 52d and the reinforcing rib 56a, a portion requiring rigidity and a thin wall portion due to the gas seal rib 52d are provided. The part that can be converted can be arranged as appropriate.

Further, as shown in FIGS. 6, 17 and 19, gas seal ribs 52d are continuously provided on the edge of the wall portion 52x, and the front cover 52 does not impair the appearance of the front cover 52. The wall portion 52x can be thinned to the vicinity of the edge portion of the wall portion 52x.

FIG. 18 is a perspective view showing the lower part of the front cover 52.
The front cover 52 includes a rear bending wall portion 56h that bends to the rear of the vehicle below the wall portion 52x.
An opening 56j is opened in the central portion of the rear bending wall portion 56h in the vehicle width direction. A horn (not shown) is arranged inside the front cover 52, and the sound of the horn is emitted to the outside of the vehicle body through the opening 56j. By providing the opening 56j, the horn volume outside the vehicle body can be secured.
The opening 56j is formed by an inclined core 85 (see FIG. 19) provided in the resin molding die 75 (see FIG. 13).

FIG. 19 is a perspective view showing the lower portion of the front cover 52 from the back surface 52a side.
At the time of injection molding of the front cover 52, the inclined core 85 is arranged on the back surface 52a of the rear bending wall portion 56h of the front cover 52.
The inclined core 85 is for treating the opening 56j (see FIG. 18) and the undercut around the opening 56j. The solid line shows the state where the inclined core 85 is arranged on the back surface 52a of the rear bending wall portion 56h, and the alternate long and short dash line is such that the inclined core 85 at the solid line position is separated from the rear bending wall portion 56h after the molten resin is solidified. Shows the state of being slid to.

FIG. 20 is a front view showing a part of the front surface 85a of the inclined core 85, and FIG. 21 is a sectional view taken along line XXI-XXI of FIG.
As shown in FIG. 20, the inclined core 85 surrounds the convex portion 85b forming the opening 56j (see FIG. 18) of the front cover 52 (see FIG. 18) and the convex portion 85b at a predetermined distance from the convex portion 85b. An annular groove 85c formed as described above is provided on the front surface 85a.
As shown in FIG. 21, the convex portion 85b of the inclined core 85 is a portion forming the opening portion 56j of the rear bending wall portion 56h. The annular groove 85c of the inclined core 85 is a portion that forms an annular gas seal rib 56k protruding from the back surface 52a of the rear bending wall portion 56h around the opening 56j.

FIG. 22 is a perspective view showing the opening 56j of the rear bent wall portion 56h of the front cover 52 and its surroundings.
A continuous annular gas seal rib 56k is formed around the opening 56j. The gas seal rib 56k is formed inside the gas seal rib 52d.
As shown in FIGS. 21 and 22, when the front cover 52 is injection-molded, the molten resin in the annular groove 85c in the inclined core 85 in the resin molding die 75 (see FIG. 12) is subjected to directional solidification. It solidifies faster than the molten resin around the annular groove 85c. As a result, the gas seal rib 56k is formed. Further, a gas seal rib 52d is continuously formed from the back surface 52a of the front cover 52 on the edge reinforcing rib 52m of the rear bending wall portion 56h of the front cover 52. From the above, the space between the gas seal rib 52d and the gas seal rib 56k in the resin molding die 75 is a closed space.
Therefore, when the pressurized gas is applied to the molten resin surrounded by the gas seal rib 52d and the gas seal rib 56k, the gas seal rib 56k prevents the pressurized gas from leaking to the opening 56j side. , The wall portion 52x around the gas seal rib 56k can be thinned. In this way, the wall thickness of the lower wall portion 52x of the front cover 52 can be reduced to the vicinity of the opening 56j.

As shown in FIGS. 6 and 13 above, the front cover 52 as a resin molded product is molded by applying a pressurized gas to the molten resin in the resin molding die 75. In the front cover 52, a gas seal rib 52d as an elongated rib-shaped protrusion is integrally formed on the wall portion 52x, and the gas seal rib 52d is arranged so as to surround a predetermined range of the wall portion 52x. The wall thickness of the wall portion 52x of the portion surrounded by the gas seal rib 52d is formed to be thinner than the wall thickness of the other portion of the wall portion 52x.

Further, in the molding method of the front cover 52 formed by applying a pressurized gas to the resin in the resin molding mold 75, a gas seal rib 52d surrounding a predetermined range on the surface of the wall portion 52x of the front cover 52 is formed on the wall portion 52x of the front cover 52. Form. By directional solidification in which the resin in the gas seal rib 52d solidifies faster than other parts, the surrounding portion 56x surrounded by the gas seal rib 52d is sealed so as to hold the pressurized gas.

According to the above configuration, the wall thickness of the front cover 52 can be reduced, and the weight of the front cover 52 can be reduced. Further, since the rigidity of the front cover 52 can be increased and reinforced by the gas seal rib 52d, the impact durability of the front cover 52 can be improved. Further, since the gas seal rib 52d can seal the pressurized gas so as not to leak to the outside, the resin molding die 75 does not require a dedicated sealing means and is not restricted by the parting line 81. The front cover 52 reinforced with the above-mentioned thin wall can be manufactured.

Further, as shown in FIGS. 18 and 22, an opening 56j is provided in the wall portion 52x, and the back surface 52a of the wall portion 52x is provided along the outer edge portion of the inner surface of the front cover 52 and the contour (edge) of the opening portion 56j. Gas seal ribs 52d are continuously provided along the portion).
According to this configuration, the wall portion 52x can be thinned to the vicinity of the opening 56j of the front cover 52 without impairing the appearance of the front cover 52.

The above-described embodiment shows only one aspect of the present invention, and can be arbitrarily modified and applied without departing from the gist of the present invention.
For example, the gas seal rib 52d may be arranged at least in a portion where the pressurized gas easily leaks along the outer edge portion of the resin molded product or the contour of the opening, and may be partially arranged without being provided all around.
The present invention is not limited to the case where it is applied to the front cover 52 of the motorcycle 40, and can be applied to parts other than the front cover 52.
Further, the present invention is not limited to the case where it is applied to the motorcycle 40, and can be applied to a saddle-riding vehicle including a motorcycle other than the motorcycle 40 and a vehicle other than the saddle-riding vehicle. Note that saddle-riding vehicles include all vehicles that ride across the vehicle body, and are not only motorcycles (including motorized bicycles), but also three-wheeled vehicles and four-wheeled vehicles that are classified as ATVs (rough terrain vehicles). It is a vehicle including.

10 Resin molded products 10a, 52d, 56k Gas seal ribs (elongated rib-shaped protrusions)
10b, 52x Wall part 10c, 56x Surrounding part 22,75 Resin molding mold 52 Front cover (resin molded product)
52a Back side (non-design side)
52m edge reinforcement rib (reinforcement rib)
52q, 52r Intermediate reinforcing rib (reinforcing rib)
56a Reinforcing rib 56d Gradually changing wall thickness 56j Opening

Claims (8)

In a resin molded product molded by applying a pressurized gas to the resin in a resin molding die (22,75),
An elongated rib-shaped protrusion (10a, 52d, 56k) is integrally formed on the wall portion (10b, 52x), and the elongated rib-shaped protrusion (10a, 52d, 56k) is within a predetermined range of the wall portion (52x). The wall thickness of the wall portion (10b, 52x) of the portion surrounded by the elongated rib-shaped protrusions (10a, 52d, 56k) is the wall thickness (10b, 52x). ) Is formed thinner than the wall thickness of other parts,
The wall portion (52x) is integrally provided with reinforcing ribs (52m, 52q, 52r, 56a) having a larger amount of protrusion from the surface of the wall portion (52x) than the elongated rib-shaped protrusion (52d). A gradually changing wall thickness portion (56d) in which the wall thickness of the wall portion (52x) gradually changes is provided between the elongated rib-shaped protrusion (52d) and the reinforcing rib (52m, 52q, 52r, 56a). A resin molded product characterized by being The elongated rib-shaped protrusion (52d) intersects the reinforcing rib (52q, 52r) at an angle of at least 20 degrees or more, and the elongated rib-shaped protrusion is higher than the height of the reinforcing rib (52q, 52r). The resin molded product according to claim 1, wherein the height of the portion (52d) is low. The resin molded product according to claim 1 or 2, wherein the elongated rib-shaped protrusion (52d) is continuously provided on the edge of the wall portion (52x). An opening (56j) is provided in the wall portion (52x), and the elongated rib-shaped protrusion (52d) is continuously provided along the contour of the opening (56j) of the wall portion (52x). The resin molded product according to any one of claims 1 to 3, wherein the resin molded product is characterized by. In the molding method of a resin molded product formed by applying a pressurized gas to a resin in a resin molding die (22,75),
An elongated rib-shaped protrusion (10a, 52d, 56k) surrounding a predetermined range on the surface of the wall portion (52x) of the resin molded product (10, 52) is formed, and the elongated rib-shaped protrusion (10a, 52d) is formed. , 56k), the resin solidifies faster than other parts, and the surrounding part (10c, 56x) surrounded by the elongated rib-shaped protrusions (10a, 52d, 56k) is covered with the pressurized gas. Seal to hold and
Reinforcing ribs (52m, 52q, 52r, 56a) having a larger amount of protrusion from the surface of the wall portion (52x) than the elongated rib-shaped protrusion (52d) are integrally formed on the wall portion (52x). Between the elongated rib-shaped protrusion (52d) and the reinforcing rib (52m, 52q, 52r, 56a), a gradually changing wall thickness portion (56d) in which the wall thickness of the wall portion (52x) gradually changes is formed. A method for molding a resin molded product, which is characterized by being provided. The elongated rib-shaped protrusion (52d) is intersected with the reinforcing rib (52q, 52r) at an angle of at least 20 degrees or more, and the elongated rib-shaped protrusion is higher than the height of the reinforcing rib (52q, 52r). The method for molding a resin molded product according to claim 5, wherein the height of the portion (52d) is lowered. The method for molding a resin molded product according to claim 5 or 6, wherein the elongated rib-shaped protrusion (52d) is continuously provided on the edge of the wall portion (52x). An opening (56j) is provided in the wall portion (52x), and the elongated rib-shaped protrusion (52d) is continuously provided along the contour of the opening (56j) of the wall portion (52x). The method for molding a resin molded product according to any one of claims 5 to 7, which is characteristic.

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