JP4887994B2 - Mold for foam molding and foam molding method - Google Patents

Description

  The present invention relates to a mold for producing a foam molded article such as urethane foam, and more particularly to a mold for foam molding having a through hole such as a mounting through hole provided in an EA material or the like. One aspect of the present invention relates to a mold configured to dispose a film along a cavity surface of a lower mold and to supply and discharge a fluid such as air between the cavity surface and the film. The present invention also relates to a foam molding method using this mold.

I: An EA material made of hard urethane foam is attached to a door trim of an automobile for energy absorption (EA) at the time of a side collision (side collision). As a method for attaching the hard urethane EA material to the door trim, there is a method using caulking as shown in FIG. 6 (paragraphs 0002 to 0003 of JP-A-2001-322507). FIG. 6 (b) is an enlarged view of a portion B in FIG. 6 (a).

  In FIG. 6, a rod 2 projects from the inner surface of a trim (door trim) 1, and the rod 2 is inserted into a through hole (attachment hole) 4 provided in the side projecting EA material 3. After the flat washer 5 is fitted to the rod 2, the distal end side of the rod 2 is crimped to form the enlarged portion 2a. Next, in order to prevent rattling of the EA material 3, the hot melt adhesive 6 is attached to the intersection corner between the side peripheral surface of the EA material and the inner surface of the trim 1.

In order to mold an EA material made of rigid urethane foam having such a through hole 4, a convex part having a shape of the through hole 4 is provided on an upper mold or a lower mold (usually an upper mold).
II: When molding rigid polyurethane foam, supply the urethane raw material liquid into the lower mold of the upper mold and lower mold, mold and foam, solidify (cure), open the mold and demold I do.

As a method for efficiently performing this demolding, JP-A-9-234748 and JP-A-2004-130629 arrange a film along the cavity surface of the lower mold, and the film and cavity are used for demolding after mold opening. A method is described in which air is supplied to the surface to separate the film from the cavity surface, and the molded product is pushed up and taken out by the film.
JP 2001-322507 A JP-A-9-234748 JP2004-130629

  When foam molding is performed with a convex portion provided on the upper die as in I above, it is extremely difficult to bring the convex portion into close contact with the inner surface of the cavity of the lower die.

  That is, when the upper die 10 and the lower die 11 are clamped and foamed as shown in FIG. 7, the length of the convex portion 12 provided on the upper die 10 is the specified length as shown in FIG. If it is slightly larger than this, a gap will occur in the parting line PL between the upper mold 10 and the lower mold 11. On the other hand, when the length of the convex portion 12 is shorter than the specified length as shown in FIG. 7 (b), the thin article-like burrs are formed in the bottom of the hole 14 in the molded product 13 as shown in FIG. 7 (c). 15 remains.

  In actual operation, as shown in FIG. 7 (b), the convex portions 12 were slightly shortened to remove the burrs 15 from the molded product, and the deburring work was troublesome.

  An object of the present invention is to solve such problems of the prior art and provide a mold for foam molding and a molding method capable of efficiently molding a molded product with a through hole.

  The mold for foam molding of the present invention is a mold for foam molding having an upper mold and a lower mold, and the through-hole-shaped convex portion for forming a through-hole in a molded product is the upper mold and In the mold for foam molding, which protrudes from the inner surface of one cavity of the lower mold and the tip surface of the convex portion abuts against the convex portion opposite the inner surface of the other cavity of the upper mold and the lower mold, the convex portion In addition, at least one of the protruding portion and the protruding portion may be elastically retractable when the two come into contact with each other.

  Moreover, the molding method of the foam molded product of the present invention is to perform molding using the mold for foam molding of the present invention.

  In one aspect of the present invention, a film is superimposed on the cavity surface of the lower mold, and the lower mold is provided with a gas supply unit for sending gas to the lower side of the film to lift the film. Yes. To perform demolding after foam molding using this mold for foam molding, the upper mold is opened, fluid is supplied between the film and the cavity surface of the lower mold, the film is pushed up, and the molded product Demold.

  In this aspect, it is preferable that the convex portion is provided on the upper mold, the convex portion opposing portion is provided on the lower die, and the convex portion opposing portion is covered with the film. In particular, the lower mold is provided with a lower mold body in which a hole is provided in the convex portion-facing portion, an insertion body that is inserted into the hole so as to be able to advance and retreat, and the insertion body that is attached to the cavity. It is preferable to include a biasing member that biases. In this case, an insertion body holder having an inner hole coaxial with the hole is attached to the outer surface portion of the lower mold, and the insertion body extends from the inner hole of the insertion body holder. You may be set as the structure arrange | positioned over the said hole of a lower mold | type.

  In the present invention, it is preferable that a positioning means for determining a forward limit position of the insertion body into the cavity is provided.

  In the present invention, the convex portion protruding from the cavity surface of the upper die or the lower die is brought into contact with the convex portion opposing portion of the cavity surface of the lower die or the upper die. In the present invention, since the convex portion or the convex portion opposing portion where the tip of the convex portion abuts is elastically retractable, the convex portion or the convex portion opposing portion is pressed against the convex portion opposing portion. The mold can be slightly retracted, and the mold can be clamped so that the upper mold and the lower mold are brought into close contact with the parting line.

  Accordingly, a thin skin-like burr does not occur at the bottom of the through hole, the upper mold and the lower mold are tightly clamped, and the occurrence of a burr on the parting line is prevented.

  Therefore, according to the present invention, a molded product with a through hole can be efficiently molded.

  In the present invention, the film is disposed along the cavity surface of the lower mold and the film is disposed along the cavity surface of the lower mold, and air is supplied between the film and the cavity surface when demolding after the mold is opened. Demolding can be performed efficiently by separating from the cavity surface and pushing up and removing the molded product by the film.

  In this case, it is preferable that the convex portion is provided on the upper mold, the convex portion opposing portion is provided on the lower die, and the lower convex portion opposing portion is covered with the film. If it does in this way, it will prevent that resin, such as urethane, penetrate | invades in the clearance gap between the insertion body which comprises a convex part opposing part, and a hole.

  In order to hold this insertion body, it is preferable to attach an insertion body holder to the lower mold and arrange the hole provided in the insertion body holder coaxially with the hole of the lower mold. If it does in this way, it becomes possible to perform maintenance of an insertion body easily by attaching or detaching an insertion body holder.

  Providing means for determining the forward limit position of the insertion body prevents the insertion body from excessively protruding into the cavity.

  Hereinafter, embodiments will be described with reference to the drawings.

  1 (a) is a sectional view of a mold for foam molding according to an embodiment, FIG. 1 (b) is an enlarged view of a part of a lower mold, and FIG. 1 (c) is a perspective view of a molded product. FIG. 2 is an exploded perspective view of the vicinity of the convex portion and convex portion facing portion of the mold, FIG. 3 is a sectional view during molding, and FIG. 4 is a sectional view during demolding. FIGS. 5A and 5B are explanatory views of another embodiment.

  In the following description, the EA material is manufactured using urethane as a resin, but the present invention can also be applied to foam molding of resin materials other than urethane and molding other than EA material.

  The mold 21 includes a lower mold 22 and an upper mold 23, and the lower mold 22 is provided with a cavity 24 made of a recess.

  In this embodiment, the film 30 is provided along the cavity surface of the lower mold 22, and a blowing means for blowing gas (preferably air) is provided between the film 30 and the cavity surface.

  The blowing means includes a chamber 32 formed by attaching an outer case 31 to the lower surface of the lower mold 22, an air blowing hole 33 that communicates the chamber 32 and the cavity surface, and an air supply / exhaust port 34 into the chamber 32. It is comprised by the pump and valve (not shown) which supply and discharge air via.

  The peripheral edge of the film 30 is superimposed on the mating surface PL of the lower mold 22 and supported on the mating surface by a packing and a pressing member (not shown).

  A molded product 40 to be molded by the mold 21 includes a disc-shaped main body 41, a mounting portion 42 that protrudes from the main body 41 in an ear piece shape, and a through-hole provided in the mounting portion 42. EA material having 43.

  In order to form the attachment portion 42, the cavity 24 includes an overhang portion 24A. The projecting portion 24A has a shape formed by partially denting the mating surface of the lower mold 22.

  Further, in order to form the through hole 43, a columnar convex portion 25 is projected from the upper mold 23. The convex portion 25 protrudes into the overhang portion 24A.

  The convex portion facing portion of the lower mold 22 facing the convex portion 25 includes a hole 50 penetrating the lower mold 22, a piston rod-shaped insertion body 51 inserted into the hole 50, and the insertion body. A coil spring 52 as an urging member for urging 51 toward the cavity 24 and a plug 53 for closing the hole 50 are provided. The plug 53 has a small diameter portion 53a inserted into the hole 50 and a flange portion 53b. As shown in FIG. 2, a bolt 54 is passed through a small opening 53 c provided in the flange portion 53 b, and the plug 53 is fixed to the lower mold 22 by this bolt 54.

  The hole 50 consists of a small diameter portion 50a on the cavity 24 side and a large diameter portion 50b on the outer surface side. The insertion body 51 includes a small diameter portion 51a and a large diameter portion 51b. The small diameter portion 51a is disposed in the small diameter portion 50a of the hole 50, and the large diameter portion 51b is disposed in the large diameter portion 50b of the hole 50. Yes.

  FIG. 1 (b) relates to the mold open state. In FIG. 1B, in the mold open state, the large diameter portion 51b is pressed against the step surface (positioning means) between the small diameter portion 50a and the large diameter portion 50b of the hole 50 by the coil spring 52. In this state, the tip of the insertion body 50 slightly protrudes into the cavity (for example, about 0.5 to 1.0 mm).

  FIG. 1 (a) relates to a clamped state. In this clamping state, the tip of the convex portion 25 is in contact with the tip surface of the insertion body 50 through the film 30, and the insertion body 50 has a substantially flush surface with the inner surface of the cavity of the lower die 22. Or it is retracted to a position where it protrudes slightly more than flush.

  In this mold 21, foam molding is performed with the film 30 in close contact with the cavity surface as shown in FIG. In removing the mold, after opening the mold, air is blown into the chamber 32, and the film 30 is pushed up as shown in FIG.

  After demolding, the chamber 32 is evacuated to bring the film 30 into close contact with the cavity surface, and the process proceeds to the next molding cycle.

  In this embodiment, since the molding is performed in a state where the tip surface of the convex portion 25 is in close contact with the tip surface of the insertion body 51, the through hole 43 exists in the through state in the molded product 40 immediately after demolding. . There is no or almost no burrs in the through-holes 43, and the molded product can be made into an EA material product without any deburring operation or simply.

  As shown in FIG. 2, the flange 53b of the plug 53 has a shape in which a circle is cut in the chord direction in parallel. This is because the plug 53 is close to the falling surface 22f of the lower mold 22 (FIG. 1 (b)).

  In the present invention, a holder for holding the insertion member 50 may be attached to the lower mold 22 as shown in FIG. 5 (a) or (b).

  In FIG. 5 (a), the holder 60 has a cylindrical shape having a flange 61, and an inner hole thereof includes a small diameter portion 62a and a large diameter portion 62b. The small diameter part 51a of the insertion body 51 faces the cavity 24 from the small diameter part 51a through the hole 50A of the lower mold 22A. The large diameter portion 52 a is disposed in the large diameter portion 62 b of the inner hole of the holder 60 and is urged toward the cavity by the coil spring 52. The outer surface side of the inner hole is closed by a plug 63. The plug 63 is screwed into the large inner diameter portion 62b.

In FIG. 5 (b), since the falling surface 22f of the lower mold 22B is close to the holder 60A, the holder 60A omits the flange 61, and instead replaces the tip 64 with a male screw with the hole 50A of the lower mold 22B. Is screwed into a female screw provided on the outer side.
In the present invention, as shown in the lower mold 22C of FIG. 8, a hole 80 is provided in the convex portion opposite to the convex portion, and an elastic body 81 such as rubber or urethane is attached to the hole 80. You may make it protrude in 24A. The distal end surface of the elastic body 81 is covered with the film 30.
In FIG. 8, the hole 80 is a concave hole and the elastic body 81 is attached by press fitting or the like, but may be attached by bolting. Instead of the concave hole, the hole 80 may be formed by a through hole and a plug attached to the rear end side of the through hole. In this case, the elastic body 81 may be attached to the plug.

  Each of the above embodiments is an example of the present invention, and the present invention can take forms other than those shown in the drawings. For example, the molded product may have a shape other than that illustrated.

It is explanatory drawing which shows embodiment. It is a disassembled perspective view of a part of metal mold | die of FIG. It is a figure of the shaping | molding method in the form of embodiment. It is explanatory drawing which shows a demolding method. It is explanatory drawing of another embodiment. It is sectional drawing of EA material. It is sectional drawing explaining the conventional method. It is a longitudinal cross-sectional view which shows a part of lower mold | type of the metal mold | die which concerns on another embodiment.

Explanation of symbols

21 Molds 22, 22A, 22B, 22C Lower mold 23 Upper mold 24 Cavity 25 Projection part 30 Film 40 Molded product 50, 50A Hole 51 Insert body 52 Coil spring 60, 60A Holder 80 Hole 81 Elastic body

Claims (8)

A mold for foam molding having an upper mold and a lower mold,
The through-hole-shaped convex portion for forming a through-hole in the molded product is projected from one cavity inner surface of the upper mold and the lower mold,
In the mold for foam molding in which the front end surface of the convex part comes into contact with the convex part opposite part of the inner surface of the other cavity of the upper mold and the lower mold,
A mold for foam molding, characterized in that at least one of the convex portion and the convex portion-facing portion can be elastically retracted when the two come into contact with each other. In claim 1, the film is superimposed on the cavity surface of the lower mold,
A mold for foam molding, wherein the lower mold is provided with a gas supply section for sending a gas to the lower side of the film to lift the film. In Claim 2, the convex part is provided in the upper mold, the convex part counter part is provided in the lower mold,
A mold for foam molding, wherein the convex portion-facing portion is covered with the film.   4. The lower mold according to claim 3, wherein the lower mold has a lower mold body provided with a hole in the convex portion facing part, an insertion body inserted in the hole so as to be able to advance and retract, and the insertion body in the cavity. A mold for foam molding, characterized by comprising a biasing member biasing in the direction. In claim 4, an insertion body holder having an inner hole coaxial with the hole is attached to the outer surface portion of the lower mold,
The foaming mold, wherein the insertion body is disposed from the inner hole of the insertion body holder to the hole of the lower mold.   6. The mold for foam molding according to any one of claims 3 to 5, further comprising positioning means for determining a forward limit position of the insertion body into the cavity.   A foam molding method using the mold for foam molding according to any one of claims 1 to 6. In Claim 7, The said metal mold | die is a metal mold | die of any one of Claim 2 thru | or 6, Comprising:
Supply raw materials into the lower mold,
After mold clamping, foam
Thereafter, the upper mold is opened, a fluid is supplied between the film and the cavity surface of the lower mold, the film is pushed up, and the molded product is demolded.

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