JP2934125B2 - Manufacturing method of mudguard for automobile - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a mudguard for an automobile.

[0002]

2. Description of the Related Art As shown in FIG. 10 of the accompanying drawings, a general automobile mudguard 50 has a mounting portion 51 having an L-shaped cross section.
And a mudguard 52 formed at the tip thereof. Reference numeral 54 denotes a mounting hole for mounting the mud guard to a tire house of a vehicle body. In the mudguard 50, the surface of the attachment portion 51 and the mudguard portion 52 are formed of a soft resin S. On the other hand, a core 53 made of a hard resin H is integrally formed inside the periphery of the mounting portion 51 and the mounting hole 54 as shown by a chain line in order to secure the mounting strength.

[0003] It is known that the molding of such a molded product in which the core portion made of the hard resin H is contained in the soft resin S, that is, the sandwich molded product is performed by, for example, a two-layer injection device having a double needle structure. I have.
A known two-layer injection device, for example, a sandwich injection molding machine of Toshiba Machine Co., Ltd., comprises an apparatus main body having an injection unit (barrel) for supplying a hard resin and an injection unit (barrel) for supplying a soft resin. The apparatus main body is provided with an inner needle valve for hard resin and an outer needle valve for soft resin. By this device, first, a soft resin constituting a product surface is injected into a mold, and then a hard resin constituting a core portion is injected. The injected hard resin flows in the mold while flushing the previously injected soft resin to form a core layer inside the product.

However, in this method, it is difficult to control the flow of the hard resin on the inside, and the hard resin sometimes flows into a portion of the molded article that is to be constituted by the soft resin. Especially in mudguards of cars,
When the hard resin flows into the mudguard portion where flexibility is required, there arises a problem that the rigidity of the surface increases and cracks and whitening occur during use.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. 3-86509, a core layer having a main body and a hard portion and a soft portion branched from the main body, wherein the main body and the hard portion are hard, Has a sandwich structure consisting of a soft skin layer coated on the surface, while the soft portion has a shape of a molded product upon forming a sandwich molded product of a synthetic resin composed of the same material as the skin layer. In the cavity, in the vicinity where the hard part forming part and the soft part forming part branch off from the main body forming part, using a molding die provided with a flow resistance part that suppresses the inflow of the skin layer material into the hard part forming part, A method for manufacturing a sandwich molded product, comprising injecting a skin layer material into a cavity through a main body forming portion and thereafter injecting a core layer material into the skin layer material is proposed. It has been.

However, even with this method, the flow of the hard resin H in the product cannot be completely controlled.
In addition, in the molding die, the portion provided with the flow resistance portion may appear as a thin portion on the product, which may lower the product strength.

The present inventors have previously formed a blocking member and a resin flow path to the mudguard cavity in advance at the distal end of the core of the cavity forming the mold cavity mounting portion. Injecting the soft tree into the cavity in an amount reduced by the amount corresponding to the cavity occupation portion and the core portion of the blocking member from the resin injection port into the cavity, and then after the start of the injection of the soft resin. Alternatively, after the injection is completed, a step of injecting the hard resin constituting the core portion from the injection port to a position reaching the blocking member while the blocking member is advanced, and then, after the injection of the hard resin is started or after the injection is completed. A step of retracting the blocking member from the cavity and injecting the soft resin or the hard resin in an amount corresponding to the cavity occupation portion of the blocking member. It was proposed a method of manufacturing an automotive mud guard, wherein (Japanese Patent Application No. 4-232724
issue).

According to this method, the hard resin injected from the gate flows while pushing the soft resin in the cavity toward the tip of the mudguard cavity portion not yet filled with the resin. Since the flow is not blocked by the mudguard cavity, the flow may flow into the mudguard cavity, and a method for more reliably controlling the flow of the hard resin has been required.

[0009]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above-mentioned problems, and a method of manufacturing a mudguard for an automobile capable of reliably controlling the flow of a hard resin in a product has been proposed. It is something to offer.

[0010]

That is, the present invention provides:
When obtaining an automobile mudguard integrally having a mounting portion having a core portion of a hard resin and a mudguard portion of a soft resin,
A resin injection port is provided at the rear end of the cavity portion forming the mounting portion of the mudguard-shaped mold cavity,
A method of molding using a two-layer injection device in which a hard resin constituting a core portion inside and a soft resin flows outside the core portion from the injection port, wherein the mounting portion cavity portion of the mold cavity is A step of injecting a predetermined amount of the soft resin into the cavity from the injection port by advancing the block member of a predetermined shape so that a resin flow path to a mudguard cavity portion is formed; Retreating the block member from the mounting portion cavity portion and injecting a predetermined amount of the soft resin and the hard resin constituting the core portion from the injection port. According to.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a molding die for carrying out the method for manufacturing a mudguard for an automobile of the present invention, FIG. 2 is a cross-sectional view taken along the line 2-2, FIG. 4 is a cross-sectional view of a molding die showing a state where the block member is retracted, FIG. 5 is a cross-sectional view of a molding die showing a state where hard resin is injected, and FIG. 6 is a cross-sectional view of a molding die showing another example of the present invention. FIG. 7 is a cross-sectional view of a molding die in which a soft resin is injected, FIG. 8 is a cross-sectional view of a molding die in which a block member is retracted, and FIG. 9 is a molding die in which a hard resin is injected. FIG.

The method for manufacturing a mudguard for an automobile according to the present invention comprises a step of injecting a soft resin and a step of injecting a hard resin together with the soft resin. The mounting portion 51 having the core 53 of the hard resin H as described above. And a mudguard portion 52 made of a soft resin S.

FIG. 1 shows an example of a molding die used in the manufacturing method of the present invention. Reference numeral 10 is a mold, 11 is a fixed mold,
Reference numeral 12 denotes a movable type, which has a cavity 13 for defining the shape of the mudguard 50. Reference numeral 14 denotes a cavity portion of the mudguard 50 that forms the attachment portion 51, and reference numeral 15 denotes a cavity portion that similarly forms the mudguard portion 52. In the cavity 13, a resin injection port 16 is provided at a rear end of the mounting portion cavity portion 14. Reference numeral 17 is a gate, and 18 is a sprue.

A block member 20 having a predetermined shape is provided in the mounting portion cavity portion 14 so as to be able to move forward and backward. The block member 20 is, as understood from FIG.
A drive device (not shown) such as a well-known cylinder device or the like provided outside the mold has a configuration substantially the same as the shape of the core portion 53 formed in the product, that is, the cavity shape that defines the shape of the attachment portion 51. ) To protrude into the cavity 13 or retreat to form the same plane as the general surface of the cavity.

In the block member 20, the hard resin flows into the mounting portion cavity portion 14 so that the mud guard 50 is formed.
At the position where the core portion 53 is formed. And FIG.
As shown in the figure, when the block member 20 is advanced to the mounting portion cavity portion 14, the resin flow for the soft resin S to the mudguard portion cavity portion 15 on its side, preferably both sides, is provided. It is arranged so that the path 25 is formed.

The above-mentioned known two-layer injection device is connected to the molding die 10, and the core 5 of the molded product 50 is provided inside.
The hard resin H that constitutes 3 and the soft resin S outside the hard resin H are injected into the cavity 13. The hard resin H and the soft resin S are not particularly limited, but are preferably thermoplastic resins having compatibility with each other. In this example, high rigid polypropylene is used for the hard resin H and rubber modified polypropylene is used for the soft resin S.

Next, the method of the present invention will be described with reference to FIGS. 2 to 5, the same reference numerals as those in FIG. 1 indicate the same members. First, FIG.
As shown in (2), the block member 20 is advanced to occupy and block the mounting portion cavity portion 14 in the mold cavity 13. At this time, as shown in FIG. 2, resin flow paths 25 are secured on both sides of the block member 20.

Then, as shown in FIG. 3, a predetermined amount of soft resin S is injected into cavity 13 from resin injection port 16. At this time, the amount of the soft resin S to be injected corresponds to an amount obtained by subtracting the volume 19 of the cavity occupied by the block member 20 from the total capacity of the cavity 13. The injected soft resin S bypasses the resin flow paths 25 on both outer sides of the block member 20 shown in FIG. 2 and flows into the mudguard cavity 15. As described above, since the cavity volume 19 occupied by the block member 20 is reduced,
It is not filled entirely but is filled around the mudguard cavity portion 15 and the block member 20.

Next, as can be understood from FIG. 4, the soft resin S is substantially filled into the mudguard cavity portion 15 by the step of injecting a predetermined amount of the soft resin, and the hard resin H and the remaining Soft resin gate 1
7, the block member 20 is retracted from the mounting portion cavity portion 14. In the mold cavity 13, a cavity 22 not filled with the soft resin S is formed by the occupation of the cavity by the block member 20. The operation timing of the block member 20 is appropriately adjusted according to the shape of the cavity and the runner of the product or the fluidity of the resin.

Thereafter, as shown in FIG. 5, a hard resin H having a volume of 19 from the resin injection port 16 of the core portion,
In addition, the soft resin S in an amount excluding the volume of the hard resin H for the core material from the volume of the block member 20 is injected into the cavity. Injected hard resin H and soft resin S
Is a cavity 2 formed by the block member 20.
2 is filled. Preferably, the hard resin H and the soft resin S are injected almost simultaneously to prevent the hard resin H from being exposed on the product surface. Then, the mold is opened to form a product.

FIGS. 6 to 9 show another embodiment of the present invention. This molding die 30 is for obtaining a mudguard 50 in which a core 53 made of hard resin H is also provided in the vicinity of a mudguard mounting hole 54 where strength is required, as shown in FIG. It has a projection forming a hole 54 and a first block member 40 for the mounting cavity.

The molding die 30 of this embodiment has two resin injection ports (gates) 36 and 37. In this example,
Soft resin S and hard resin H are injected into cavity 33 via gates 36 and 37. The gate 37 is for injecting the hard resin H into the vicinity of the protrusion 39. That is, the runner portion 49 of the gate 37
Is provided with a second block member 41. The second block member 41 is provided to be able to move forward and backward with respect to the runner portion 49 by a driving device 43,
The runner 49 is shut off or opened. Since the operation of the first block member 40 is the same as described above, the details are omitted.

According to the molding die 30 of this embodiment, first, the first block member 40 is advanced and the second block member 41 is advanced to shut off the runner portion 49. Next, as shown in FIG. 7, a predetermined amount of soft resin S is injected into the cavity 33 from the gate 36, and is filled into the mounting portion cavity portion 34 and the mudguard cavity portion 35.

Thereafter, as shown in FIGS. 8 and 9, the first block member 40 is retracted and the runner portion 4 is moved.
The second block member 41 that has blocked 9 is retracted,
A predetermined amount of hard resin H is injected into the cavity from gates 36 and 37. As a result, a core portion is formed near the protrusion 39. The amount of the hard resin H injected near the protrusion 39 can be appropriately determined according to the shape of the molded product and the required strength. If the opening time of the second block member 41 is appropriately set by a timer or the like, the second block member 41 can be automatically operated.

Thereafter, the soft resin S is injected into the cavity also from the gate 36 and, if necessary, the gate 37,
It is formed into a predetermined shape. In this embodiment, runner portions 48 and 49 connected to gates 36 and 37 are provided.
Are connected to each other.

[0026]

As shown and described above, according to the method for manufacturing a mudguard for an automobile of the present invention, the mudguard portion is first formed by the step of injecting the soft resin.
Since the space for the hard resin is formed by the block member, it is possible to prevent the core portion from being formed in a portion that is not required, and to reliably control the flow of the hard resin. Therefore, it is possible to obtain a product that makes full use of the properties of the resin without cracking or whitening of the mudguard portion.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a molding die for implementing a method of manufacturing a mudguard for an automobile according to the present invention.

FIG. 2 is a sectional view taken along the line 2-2.

FIG. 3 is a cross-sectional view of a molding die showing a state in which a soft resin is injected.

FIG. 4 is a cross-sectional view of a molding die showing a state where a block member is retracted.

FIG. 5 is a sectional view of a molding die showing a state where a hard resin is injected.

FIG. 6 is a sectional view of a molding die showing another example of the present invention.

FIG. 7 is a cross-sectional view of a molding die showing a state in which a soft resin is injected.

FIG. 8 is a cross-sectional view of the molding die showing a state where the block member is retracted.

FIG. 9 is a sectional view of a molding die showing a state where a hard resin is injected.

FIG. 10 is a perspective view showing an example of a general automobile mudguard.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Molding die 11 Fixed die 12 Movable die 13 Cavity 14 Attachment part cavity part 15 Mudguard part cavity part 20 Block member

Continuation of the front page (56) References JP-A-6-297504 (JP, A) JP-A-6-55575 (JP, A) JP-A-4-365681 (JP, A) JP-A-4-305415 (JP) JP-A-3-86510 (JP, A) JP-A-3-86509 (JP, A) JP-A-2-206518 (JP, A) JP-A-5-11934 (JP, A) 3-500991 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B29C 45/00-45/84

Claims (1)

(57) [Claims] When obtaining an automobile mudguard integrally having a mounting portion having a core portion of a hard resin and a mudguard portion of a soft resin, a portion of the cavity portion forming the mounting portion of the mudguard-shaped mold cavity is provided. Provide a resin inlet at the rear end,
A method of molding using a two-layer injection device in which a hard resin constituting a core portion inside and a soft resin flows outside the core portion from the injection port, wherein the mounting portion cavity portion of the mold cavity is Advance the block member of a predetermined shape so that a resin flow path to the mudguard cavity portion is formed,
A step of injecting a predetermined amount of the soft resin from the injection port into the cavity, and then retreating the block member from the mounting portion cavity portion, and removing the core portion together with a predetermined amount of the soft resin from the injection port. And a step of injecting the constituent hard resin.