JP3062141B2 - Mudguard manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a mudguard for a vehicle.

[0002]

2. Description of the Related Art A mudguard (mudguard) is attached to a vehicle in order to prevent mud splashing due to rotation of a tire. As shown in FIG. 5 and FIG. 6 showing a cross section of the mud guard, a main body 51 and a mounting portion 53 to the vehicle body are provided.
It is generally composed of a hanging portion 55 extending downward from them and having a substantially Y-shaped cross section. Reference numeral 56 denotes a bolt hole for fixing to a vehicle body.

The mudguard hardens the main body portion 51 and the mounting portion 53 from the viewpoint of mounting strength to the vehicle body and the like, while the hanging portion 55 is preferably flexible in consideration of the contact of the lower end when the step portion runs. It has been. Further, it is preferable that the surfaces of the main body portion 51 and the mounting portion 53 are made flexible so as to prevent the surfaces from being damaged by collision of pebbles or the like. Therefore, the main body 51 and the mounting portion 53 are hard core resin 6
1 is covered with a flexible surface resin 63, and the hanging portion 55 is mainly composed of the flexible surface resin 63.
Has been proposed.

Conventionally, in order to obtain a mudguard having the sandwich structure, as shown in FIGS. 7A and 7B, a mudguard body forming space 71 in an injection mold 70 is provided.
First, a soft surface resin 53 is injected into a mudguard molding space 73 in a molten state from a gate 72 located at the tip of
Next, a sandwich molding method in which the hard core resin 51 is injected into the mudguard molding space 73 in a molten state, and the core resin 51 enters the surface resin 53 is performed. However, according to this method, the amount of the surface resin 53 injected from the gate 72 into the mudguard molding space 73 into the mudguard mounting portion molding space 75 and the hanging portion molding space 76 cannot be controlled, and the mounting portion molding depends on the shape and the like. Space 7
5 and the amount of flow into the hanging portion forming space 76 are greatly affected. Therefore, when the core resin 51 is injected, the surface resin 51
In this case, a large amount of the core resin 51 flows into a portion having a low filling rate, and there is a problem that a portion that originally requires flexibility or rigidity cannot be made to have desired flexibility or rigidity.

Therefore, in the injection mold 70, a flow resistance convex portion (not shown) is formed on the mold surface 77 near the base of the mudguard mounting portion forming space 75, and the mudguard body portion is formed from the gate 72. The surface resin 53 injected through the space 71 is guided to the mudguard hanging portion forming space 76 such that the surface resin 53 cannot freely enter the mudguard mounting portion forming space 75 by the flow resistance convex portion.

However, the flow resistance convex portion makes it difficult for not only the surface resin 53 but also the core material 51 to enter the mounting portion forming space 75, so that the core material resin 51 is inserted into the mounting portion forming space 75.
May not be sufficiently filled, and as a result, the rigidity of the resulting mounting portion of the mudguard may be reduced, or the resin may be insufficiently filled (short shot). Further, in order to balance the resin inflow into the mudguard mounting portion forming space 75 and the hanging portion forming space 76, the height of the fluid resistance resistance convex portion must be adjusted. However, the adjustment is difficult and the man-hour is reduced. There were many such problems.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is a manufacturing method capable of reliably and easily obtaining a mudguard which is hard in a main body portion and a mounting portion and flexible in a hanging portion. It provides a method.

[0008]

According to the present invention, a mudguard having a sandwich structure composed of a hard core resin and a soft surface resin comprising a main body, a mounting portion, and a hanging portion extending downward from the main body is injected. In molding, the temperature of the mold surface forming the lower surface side and the hanging portion of the mudguard body and the mounting portion in the injection mold is higher than the temperature of the mold surface forming the upper surface side of the mudguard body and the mounting portion. Then, a molten surface resin in an amount smaller than the entire capacity of the mudguard molding space of the injection molding die and larger than the capacity of the mudguard hanging molding space was injected into the mudguard molding space to fill the mudguard hanging molding space. rear,
The hanging portion is formed of a soft surface resin by injecting a molten core resin into the mudguard molding space.

[0009]

FIG. 1 is a sectional view of an injection mold according to an embodiment of the present invention, FIG. 2 is a sectional view of an injection mold showing a surface resin being injected, and FIG. 3 is a sectional view of a core resin being injected. FIG. 4 is a cross-sectional view of a mudguard obtained according to an embodiment of the present invention.

An injection molding die 10 shown in FIG. 1 is used in one embodiment of the method for manufacturing a mudguard of the present invention, and comprises an upper die 11 and split lower dies 15, 19, and the mudguard is formed by closing the mold. A molding space 23 is formed inside, and a known sandwich molding injection molding machine (not shown) is connected. The mudguard molding space 23 has the shape of the mudguard in FIG. 5 described in the description of the related art, and has a main body molding space formed between the mold surface 12 of the upper mold 11 and the mold surface 16 of one lower mold 15. 24, a mounting portion forming space 25 formed between the mold surface 13 of the upper mold 11 and the mold surface 20 of the other lower mold 19, and the mold surface 1 of the opposed lower molds 15 and 19.
The hanging part forming space 26 is formed between the first and second hanging parts 7 and 21. Reference numeral 27 denotes an injection gate formed in communication with the tip of the main body forming space 24, and reference numeral 28 denotes a flow resistance convex portion formed at the root of the mounting portion forming space 25.

The injection molding die 10 is capable of efficiently filling an injection resin into the mudguard molding space 23 and controlling the temperature in order to mold a mudguard having desired hardness and flexibility. The temperature is controlled by the mold surfaces 16, 19 of the lower dies 15, 19 for molding the lower surface of the main body portion of the mudguard and the lower surface of the mounting portion.
20 and a lower mold 15, 1 for forming the hanging part of the mudguard
The temperature of the mold surfaces 17 and 21 of the mold 9 is made higher than the temperatures of the mold surfaces 12 and 13 of the upper mold 11 for forming the upper surfaces of the main body portion and the mounting portion of the mudguard. This temperature difference varies depending on the resin to be injected, but is usually several degrees to several tens degrees, and is a temperature at which the injection resin can be cured. The temperature control is performed by disposing a pipe 29 in the injection mold 10 as in this example,
By making the temperature of the water flowing through the pipe different depending on the part of the injection mold, or by circulating the water at the same temperature by changing the interval of the pipe 29 depending on the part of the injection mold, or by another method as appropriate. Done.

Next, an embodiment of manufacturing a mudguard using the injection mold 10 will be described. First, the temperatures of the mold surfaces 16, 20 of the lower dies 15, 19 for molding the lower surface of the main body portion and the lower surface of the mounting portion of the mud guard, and the mold surfaces 17, 21 of the lower dies 15, 19 for molding the hanging portion of the mud guard, are shown. ,
The temperature is controlled to be higher than the temperatures of the mold surfaces 12, 13 of the upper mold 11 for molding the upper surface of the main body portion and the mounting portion of the mudguard. As an example, the mold surfaces 16, 17, 20, 21 of the lower molds 15, 19
Is 50 ° C., and the mold surfaces 12 and 13 of the upper mold 11 are 5 ° C.

In the temperature-controlled injection mold 10, FIG.
(A), the molten surface resin 31 is injected from the gate 27. As the surface resin 31 to be used, a flexible resin having a lower rigidity than a core material resin described later, for example, an olefin elastomer is used. The injection amount is smaller than the entire volume of the mudguard molding space 23 and the mudguard hanging portion molding space 26 is formed. The amount is set to be larger than the capacity.

In the injection molding die 10 into which the surface resin 31 is injected, the curing of the surface resin 31 progresses in a portion where the surface temperature of the mold is low, and the fluidity is reduced. Is delayed and the fluidity is kept good.
Therefore, the mudguard molding space 23 of the injection mold is used.
The molten surface resin 31 injected into the lower mold 1 having a high mold surface temperature as shown in FIGS.
Flow along 5,19 mold surfaces 16,17,21,20,
Mudguard hanging part forming space 2 without directly entering mounting part forming space 25 from mudguard body part forming space 24
6 and fills the hanging part forming space 26, the remaining surface resin enters the mudguard mounting part forming space 25. Further, in this example, the surface resin 31 is also formed by the flow resistance convex portion 28 formed at the root of the mudguard mounting portion forming space 25 so that the mudguard body portion forming space 2 is formed.
4 is prevented from directly entering the mounting portion forming space 25, and is guided to the mudguard hanging portion forming space 26. Thereby, the mudguard hanging part forming space 26 is reliably filled with the surface resin 31, and the space S where the molten surface resin 31 is not filled is formed in the mounting part forming space 25. Further, the surface resin 31 in the mudguard molding space 23 has a reduced fluidity due to a decrease in temperature after injection.

Next, as shown in FIG.
From 7, a hard core resin 33, for example, hard polypropylene, is injected in a molten state into the molding space 23 of the mudguard.
The injection amount is determined by the gap S of the mudguard molding space 23.
Is satisfied or slightly larger. The core resin 33 injected into the mudguard molding space 23 pushes into the surface resin 31 of the mudguard body molding space 24 continuing from the gate 27 as shown in FIGS. It reaches the mudguard mounting part forming space 25.
At this time, since the mudguard hanging part forming space 26 is already filled with the surface resin 31 and the fluidity of the surface resin 31 has decreased due to the temperature decrease after injection as described above, the core material resin 33 has the mudguard hanging part. Molding space 26
And enters the mudguard mounting space 25 where the surface resin 31 is easily pressed due to the presence of the space S. The surface resin 31 and the core resin 33 fill the entire mudguard forming space 23.

Thereafter, when the injection molding die is opened and the molded product is released, as shown in FIG. 4, the main body portion 41 and the mounting portion 43 are constituted by the hard core resin 33 and the soft surface resin 31, and The hanging portion 45 is made of the flexible surface resin 31, the main body portion 41 and the mounting portion 43 are hard, and the desired mudguard 40 in which the hanging portion 45 is formed flexibly is obtained.

[0017]

As described above, according to the present invention, according to the present invention, the lower surface side of the main body portion and the mounting portion of the mud guard in the injection molding die and the mold surface forming the hanging portion are formed by the main body portion and the mounting portion of the mud guard. Injecting a soft surface resin into the mudguard molding space of the injection molding mold at a higher temperature than the mold surface that forms the upper surface, and then injecting the hard core resin into the mudguard molding space, the surface that was previously injected The resin is guided into the mudguard hanging space with good fluidity by the high temperature mold surface, and fills the mudguard hanging space, so that the mudguard having a flexible hanging part and a hard body and mounting part is simple and easy. Obtained reliably.

[Brief description of the drawings]

FIG. 1 is a sectional view of an injection mold according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an injection mold showing a state of injection of a surface resin.

FIG. 3 is a cross-sectional view of an injection mold showing a state at the time of injection of a core resin.

FIG. 4 is a cross-sectional view of a mudguard obtained according to an embodiment of the present invention.

FIG. 5 is a perspective view of a general mudguard.

FIG. 6 is a sectional view of FIG. 5;

FIG. 7 is a sectional view of an injection mold used for manufacturing a conventional mudguard.

[Explanation of symbols]

REFERENCE SIGNS LIST 10 Injection molding die 11 Upper die 12, 13 Mold surface for molding upper surface of mudguard main body and mounting portion 15 Lower die 16, 20 Mold surface for molding lower surface of mudguard main body and mounting portion 17, 21 Hanging of mudguard Mold surface for forming part 23 Mudguard forming space 24 Mudguard body forming space 25 Mudguard mounting part forming space 26 Mudguard hanging part forming space 27 Gate 28 Flow resistance convex portion 31 Surface resin 33 Core material resin 41 Mudguard main body 43 Mudguard mounting Part 45 Mudguard hanging part

Continuation of the front page (56) References JP-A-4-126212 (JP, A) JP-A-1-233178 (JP, A) JP-A-3-86509 (JP, A) JP-A-7-16878 (JP) JP-A-4-365681 (JP, A) JP-A-63-139719 (JP, A) JP-A-3-272824 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B29C 45/16 B29C 45/73 B62D 25/18

Claims (1)

(57) [Claims] When injection molding a mudguard having a sandwich structure composed of a hard core material resin and a soft surface resin comprising a main body portion, a mounting portion, and a hanging portion extending downward therefrom, an injection molding die is used. The temperature of the mold surface forming the lower surface side and the hanging portion of the mudguard body and the mounting portion is higher than the temperature of the mold surface forming the upper surface side of the mudguard body portion and the mounting portion, and the mudguard of the injection molding die is formed. After injecting the molten surface resin in an amount smaller than the entire molding space volume and larger than the capacity of the mudguard hanging molding space into the mudguard molding space and filling the mudguard hanging molding space, the molten core resin And forming the hanging portion with a flexible surface resin by injecting the resin into the mudguard molding space.