JPH11268045A - Die assembly for molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of burrs due to the non-uniformity of a face pressure between a P and L plane or the generation of burrs in a region where filling a gap is difficult between the P and the L planes, from occurring in a die device for molding. SOLUTION: A die is composed of a bottom force 11 and a top force 21, and a P and an L plane 12, 22 and cavity faces 13, 23 are formed on the inner surfaces of the bottom force 11 and the top force 21. Further, the outer surfaces of the bottom and the top force 11, 21 are fitted to die plates 16, 26 through spacers 15, 25. When clamping the die, the cross section shape of spacers 15, 25 is made almost identical to the shape, of the cavity faces 13, 23, projected to the outer surfaces of the bottom and the top force 11, 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus in which a mold comprises at least two split molds.

[0002]

2. Description of the Related Art FIGS. 11 to 14 show a conventional molding apparatus for RIM (reaction injection) molding of a polyurethane coating on a core metal of a steering wheel. An upper mold 61 is provided. PL (parting line) surfaces 52 and 62, which are in contact with each other at the time of mold clamping, are provided on the upper surface of the lower die 51 and the lower surface of the upper die 61,
Plane ring-shaped cavity surfaces 53 and 63 are provided. Dotted hatched portions forming the cavity surfaces 53 and 63 are formed by electroforming shells 57 and
67.

The lower surface of the lower die 51 is attached to a lower die plate 56 via a lower die mounting plate 54. Upper die 6
The upper surface of 1 is mounted on an upper die plate 66 via an upper mounting plate 64 and an upper spacer 65. The core of the steering wheel includes an ejector pin 58 whose center boss 1a extends from the lower die mounting plate 54 and an upper die mounting plate 6.
The entire ring portion 1b and a part of the spoke portion 1c are arranged at the center of the cross section of the cavity 70.

[0004] In a general molding die apparatus, the distance between the lower die plate 56 and the upper die plate 66 is determined, and dies having various heights are mounted and replaced (step change) at the distance.
As a result, spacers are used to bridge the difference between the spacing and the mold height and to prevent the mold height from being unnecessarily increased and weighted.
As shown in FIG. 12, the upper die spacer 65 of the present device is provided with four round bar-shaped members so as to support four points at 90-degree intervals with respect to the center of the upper surface of the upper die 61. The number is slightly increased or decreased depending on the size and type of the mold.

[0005]

However, the conventional molding apparatus has the following problems. (1) At the time of mold clamping, the upper mold spacer 65 partially presses only four points on the upper surface of the upper mold 61. Since the upper mold 61 is not a completely rigid body and inevitably suffers from slight bending, the sum of the four pressing forces, that is, the mold clamping force is reduced by the cavity surfaces 53 and 63.
Cannot be expected to be equally distributed on the PL surfaces 52, 62 over the entire circumference of the ring. Therefore, at the time of mold clamping, the surface pressures of the PL surfaces 52 and 62 indicated by arrows pointing up and down in FIG.
The plane pressures of the PL surfaces 52 and 62 become high at portions corresponding to the four points pressed by the upper die spacer 65, for example, at the portions corresponding to the four points pressed by the upper die spacer 65. PL surfaces 52, 6 at the portions corresponding to
2, the surface pressure decreases.

Further, since the accuracy of the flatness and the parallelism between the lower die plate 56 and the upper die plate 66 is not so high, the PL surfaces 52, 62 also have a relatively low parallelism accuracy and a relatively slight inclination. doing. Therefore, the PL surfaces 52, 6
The surface pressure of the portion that first comes into contact with the mold at the time of mold clamping is high, but the surface pressure of the portion that comes into contact last is low.

For these reasons, when the polyurethane material is injected, there is a problem that the polyurethane material 71 protrudes into the portions of the PL surfaces 52 and 62 where the surface pressure is low, as indicated by a horizontal arrow in FIG. .

(2) Since the portion of the cavity 70 where the ring portion 1b of the metal core is arranged is horizontal, the surrounding PL
The surfaces 52 and 62 are formed two-dimensionally. However, FIG.
As shown in FIG. 14 and FIG. 14, since the portion of the cavity 70 where the spoke portion 1c of the metal core is disposed is inclined,
The surrounding PL surfaces 52 and 62 are formed three-dimensionally.
Conventionally, such three-dimensional alignment of the PL surfaces 52 and 62 is performed by cut and try using a tripress. In this fitting method, a three-dimensional P
It is difficult to close the gap between the L surfaces 52 and 62 (eliminating the gap), and the gap 72 is inevitably left as shown in FIG.
The protruding portion appears as burrs 3 on the polyurethane coating 2 as shown in FIG. Therefore, a deburring step was required after molding.

[0009] An object of the present invention is to solve the above-mentioned problems and to provide a PL
A molding die capable of preventing or reducing burrs due to uneven surface pressure of the surfaces and burrs at locations where it is difficult to close gaps between PL surfaces, thereby eliminating or reducing the deburring step after molding. It is to provide a device.

[0010]

In order to achieve the above object, according to a first aspect of the present invention, a mold is constituted by at least two divided molds, and a PL surface and a cavity surface are provided on an inner surface of the divided mold. In a molding apparatus in which the outer surface of the mold is attached to a die plate via a spacer,
The cross-sectional shape of the spacer is substantially the same as the shape in which the cavity surface is projected onto the outer surface of the split mold so that the surface pressure of the L surface becomes substantially uniform over the entire circumference of the cavity surface.

Here, it is preferable to interpose an elastic body between the spacer and the die plate or the split mold that does not reach the compression limit unless a force greater than the mold clamping force of the split mold is applied.
Although it does not specifically limit as an elastic body, Many springs arrange | positioned at equal intervals can be illustrated.

According to a second aspect of the present invention, there is provided a molding die apparatus comprising a mold comprising at least two split dies, wherein a PL surface and a cavity surface are provided on an inner surface of the split die.
Form a recess along the surface facing the cavity surface, attach a gap filling member made of an elastic material showing a large elastic elongation to the recess, and when opening the mold, the surface of the gap filling member protrudes from the PL surface, The parting surface of the gap-filling member is separated from the cavity surface, and at the time of mold clamping, the gap-filling member is elastically compressed and deformed by another split mold until the surface of the gap-filling member is at the same level as the PL surface. The parting surface of the gap filling member is substantially flush with the cavity surface. Examples of the elastic material include rubber, thermoplastic elastomer, and soft resin.

According to a third aspect of the present invention, there is provided a molding apparatus in which a mold is constituted by at least two divided molds, and a PL surface and a cavity surface are provided on an inner surface of the divided mold.
The surface is formed with a recess facing the cavity surface, and the recess is fitted with a gap-filling member made of a plastic material that exhibits only a small elastic elongation and transitions to plastic deformation, and the gap-filling member is a mold for finishing. The surface of the gap filling member is made to protrude from the PL surface at the time of opening, and is plastically deformed by another split mold until the surface of the gap filling member is at the same level as the PL surface at the time of mold clamping for finishing, so that the gap filling member is formed. Is formed so that the parting surface protrudes into the cavity, and the protruding part is cut off so that the parting surface is substantially flush with the cavity surface. Examples of the plastic material include hard resin and metal.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 to 10 show an embodiment in which the present invention is embodied in a molding apparatus for RIM molding a polyurethane coating on a core of a steering wheel. The mold includes a lower mold 11 and an upper mold 21. The upper surface which is the inner surface of the lower die 11 and the upper die 2
The lower surface, which is the inner surface of P1, has P
L faces 12, 22 and a planar ring-shaped cavity face 13,
23 are provided. Dotted hatched portions forming the cavity surfaces 13 and 23 are electroformed shells 17 and 27 having a textured (eg, grained) pattern on the surface. In addition,
A grain pattern may be formed directly on the cavity surface without using an electroforming mold.

The lower surface, which is the outer surface of the lower die 11, is connected to the lower die plate 1 via the lower mounting plate 14 and the lower spacer 15.
6 attached. The upper surface which is the outer surface of the upper die 21 is attached to the upper die plate 26 via the upper die mounting plate 24 and the upper die spacer 25. The core metal of the steering wheel is such that the center boss 1a is
Is held between an ejector pin 18 extending from the upper die mounting plate 24 and an anti-sticking pin 28 extending from the upper die mounting plate 24, and the entire ring portion 1b and a part of the spoke portion 1c are
0 is located at the center of the cross section.

Also in the present apparatus, the distance between the lower die plate 16 and the upper die plate 26 is determined, and dies having various heights can be mounted and exchanged (step change) at the distance. In order to fill the difference between the interval and the height of the mold, and to prevent the height of the mold from becoming unnecessarily large and heavy, the spacers 1 are provided on both the lower mold 11 and the upper mold 21.
5, 25 are used.

In this apparatus, FIGS. 1, 2 and 3
As shown in the figure, when the lower mold 11 and the upper mold 21 are
The cross-sectional shape of the lower mold spacer 15 is set such that the portion of the cavity surface 13 where the ring portion 1b is arranged is set so that the surface pressure of the surfaces 12 and 22 is substantially uniform over the entire circumference of the cavity surfaces 13 and 23. It has a planar ring shape substantially the same as the shape projected on the lower surface. Similarly, the cross-sectional shape of the upper die spacer 25 is such that the portion of the cavity surface 23 where the ring portion 1 b is arranged is projected on the upper surface of the upper die 21. The shape is substantially the same as that of the flat ring.

The projected shape of the portion of the cavity surfaces 13 and 23 where the spokes 1c are arranged is reflected in the cross-sectional shape of the spacers 15 and 25 (since the cross-sectional shapes are complicated and difficult to create). However, it is preferable to reflect the uniformity of the surface pressure in a thorough sense.

The lower die spacer 15 is fixed to the lower die 11 and the lower die mounting plate 14 by bolts (not shown). A groove 33 is formed at the upper end surface of the lower die spacer 15 at the center in the surface width direction.
Is formed, the ridges 34 are formed on the outer peripheral portion and the inner peripheral portion.
Are formed relatively, and these ridges 34 are located corresponding to the PL surfaces 12 and 22 on the outer peripheral side and the inner peripheral side of the cavity surfaces 13 and 23 in the form of planar rings, respectively.
The surface pressure is easily applied to the surfaces 12 and 22. In addition,
These grooves 33 and protrusions 34 may be omitted.

The upper die spacer 25 is not fixed to the upper die 21 and the upper die mounting plate 24, but is supported by the following structure and presses the lower die 11.

That is, a large number (27 in the illustrated example) of through holes 35 penetrating vertically are provided at equal intervals in the upper die spacer 25, and a support tube 36 is inserted into each through hole 35. The lower end of the support tube 36 is in contact with the upper surface of the upper die mounting plate 24. The upper end of each support tube 36 is located on the upper mounting plate 24.
Slidably penetrate a central portion of a bottom portion 38 of a plurality of bottomed holes 37 provided on the bottom surface, and a flange portion 39 integrally formed at an upper end of each support tube 36 can be locked to the bottom portion 38 from above. It has become. A mounting bolt 40 is passed through each support tube 36, and a screw portion 41 below the mounting bolt 40 is provided.
Is screwed onto the upper mold 21 and the upper head 4 of the mounting bolt 40 is
2 is locked to the upper end surface of the support tube, so that each support tube 3
6 is attached to the upper mold 21. Then, the upper die spacer 25 is formed by all the support tubes 36 and the mounting bolts 40.
Is supported. Note that a groove 33 and a ridge 34 may be provided on the lower end surface of the upper die spacer 25 like the upper end surface of the lower die spacer 15.

Each through hole 3 in the upper end surface of the upper die spacer 25
The spring accommodating recesses 43 are formed at equal intervals in a position concentric with the coil spring 5, and the coil springs 44 accommodated in the respective spring accommodating recesses 43 are formed.
Are interposed between the inner bottom surface of the spring accommodating recess 43 and the lower surface of the upper die mounting plate 24. In the present device, a large number (27 in the illustrated example) of the coil springs 44 are arranged at equal intervals.
Thereby, an elastic body which does not reach the compression limit unless a force higher than the clamping force of the lower mold 11 and the upper mold 21 is applied is constituted.

At the time of opening the mold, as shown in FIG.
The length of the upper die spacer 25 is determined so that a gap 45 is formed between the upper end surface of the upper die spacer 25 and the lower surface of the upper die mounting plate 24. 39 is engaged with the bottom 38.

When the mold is clamped, the upper mold 21 rests on the lower mold 11 to release the engagement between the flange 39 and the bottom 38 as shown in FIG. And the upper end surface of the upper die spacer 25 approach, and all the coil springs 44 are compressed. However, as described above, unless a force higher than the mold clamping force is applied, all the coil springs 44 are set so as not to reach the compression limit and the gap 45 is not eliminated, so that when the mold clamping shown in FIG. Also in the gap 45
Has become smaller but remains. Therefore, the clamping force is transmitted to the upper die 21, the upper mounting plate 24, the coil spring 44, the upper spacer 25, and the upper die 21, and is applied to the upper die 21.

The ring part 1b of the core metal in the cavity 30
Is placed horizontally, so the surrounding PL surface 1
2, 22 are formed two-dimensionally. However, as shown in FIGS. 1 and 6, the portion of the cavity 30 where the spoke portion 1 c of the core metal is disposed is inclined, so that the surrounding PL surfaces 12 and 22 are formed three-dimensionally. . In order to fill the gap between the three-dimensional PL surfaces 12 and 22 in which it is difficult to fill the gap, in the present apparatus, the following gap filling member 5 is used.
Is provided.

As shown in FIG. 6 and FIG.
The L surface 12 has a width of 3 mm along the cavity surface 13.
A shallow recess 46 having a depth of 0.2 mm is formed.
A mounting groove 47 having a width of 1 mm and a depth of 1.2 mm is formed at the center in the width direction. As shown in FIG. 7A, the gap-filling member 5 has a width of 2 mm, a thickness of 0.3 mm, and is elongated in a direction perpendicular to the paper surface of FIG.
1mm wide and 1.2mm high protruding downward from the lower surface of a
The elongated mounting portion 5b in the direction perpendicular to the plane of the drawing is integrally formed of an elastic material such as rubber, thermoplastic elastomer, or soft resin exhibiting a large elastic elongation. Gap filling body 5a
Is applied to the concave portion 46 near the cavity surface 13, and the mounting portion 5 b is mounted by being fitted into the mounting groove 47.

When the mold is opened before molding in FIG. 7A, the upper surface of the gap filling main body 5a is
Project 0.1 mm above 2. In addition, the cavity-facing parting surface 5c of the gap filling body 5a is recessed from the cavity surface 13 to the side opposite to the cavity by an amount α.

At the time of the mold clamping shown in FIG. 7B, until the upper surface of the gap filling main body 5a is at the same level as the general PL surface 12,
The gap closing main body 5a is elastically compressed and deformed in the vertical direction by the upper die 21, and the gap between the PL surfaces 12, 22 is completely eliminated.
Further, the gap filling main body portion 5a elastically expands and deforms in the horizontal direction by the amount of the elastic compressive deformation in the vertical direction, and in particular, elastically expands and deforms by the amount of expansion α or α + β toward the cavity. In the case of the extension amount α, the parting surface 5c of the gap closing main body 5a is temporarily
It is substantially flush with the cavity surface 13. If it is necessary to consider the elastic compression deformation of the gap filling body 5a to the side opposite to the cavity due to the filling pressure of the polyurethane material described below, the parting surface 5c of the gap filling body 5a is
The extension amount α + β so that only the extension amount β
Is set.

When the polyurethane material is injected in FIGS. 7C and 6, the parting surface 5 c of the gap filling main body 5 a forms a parting with the polyurethane coating 2 and the polyurethane coating 2 is formed.
Part of the surface is molded. When the protrusion amount β is set, the gap filling main body 5a is elastically compressed and deformed by the compression amount β toward the opposite cavity side by the filling pressure of the polyurethane material 31, and the parting surface 5c of the gap filling main body 5a becomes It is substantially flush with the cavity surface 13.

When the mold is opened after molding, the gap filling main body 5a is opened.
Is elastically restored to the state shown in FIG.

According to the molding die apparatus configured as described above, the following operations and effects can be obtained. (1) At the time of mold clamping, the lower mold spacer 15 and the upper mold spacer 25 formed in a flat ring shape are respectively formed in a shape projected on the cavity surface 13 on the lower surface of the lower mold 11 and the upper mold 21.
Of the cavity surface 23 projected on the upper surface of the cavity surface 23, the mold clamping force is equally distributed on the PL surfaces 12, 22 over the entire ring of the cavity surfaces 13, 23. Therefore, at the time of mold clamping, the PL indicated by the upward and downward arrows in FIG.
When the surface pressure of the surfaces 12 and 22 is equal to that of the flat ring-shaped cavity surface 1
It becomes substantially uniform over the entire circumference of 3, 23 rings.

Further, since the accuracy of the flatness and the parallelism between the lower die plate 16 and the upper die plate 26 is not so high, the PL surfaces 12 and 22 also have relatively low parallelism accuracy and a relatively slight inclination. doing. However, in the present device, the coil spring 44 absorbs the inclination within the range of the gap 45, and makes the surface pressures of the first and last contacting parts of the PL surfaces 12 and 22 at the time of mold clamping substantially uniform. I do.

For these reasons, in this apparatus, the PL surface 1
Since a portion having a low surface pressure is unlikely to be generated in each of the PLs 2 and 22, the polyurethane material 31 is less likely to protrude between the PL surfaces 12 and 22 when the polyurethane material is injected as shown in FIG. 5, and burrs can be almost eliminated. A deburring step after molding can be omitted or reduced.

(2) As described above, the three-dimensional PL surface 1
In order to close the gap between the lower mold 2 and the lower mold 22,
A recess 4 along the PL surface 12 of the first surface facing the cavity surface 13
6, a gap filling member 5 made of an elastic material is formed in the recess 46.
When the mold is clamped, the gap filling body 5a is elastically deformed in the vertical direction by the upper mold 21 until the upper surface of the gap filling body 5a is at the same level as the general PL surface 12. The gap between the surfaces 12 and 22 is completely eliminated, and the polyurethane material 31 does not protrude between the PL surfaces 12 and 22 when the polyurethane material is injected. Therefore,
The occurrence of burrs 3 as shown in FIG. 15 can be eliminated, and the deburring step after molding can be omitted.

The parting surface 5c of the gap filling main body 5a
Is separated from the cavity surface 13 when the mold is opened before molding, but is substantially flush with the cavity surface 13 when the mold is clamped. Therefore, when the polyurethane material is injected, the parting surface 5c partially covers the surface of the polyurethane coating 2. Molded with almost no steps.

Next, FIG. 8 shows a modification of the gap filling member 5, in which the mounting portion 5b is formed in an undercut shape so as to prevent the mounting portion 5b from falling out of a mounting groove (not shown) having a corresponding shape. . FIG. 9 shows another modification of the gap filling member 5,
The mounting portion 5b has a U-shaped cross section. As described above, the gap filling member 5 can be variously modified as long as it has the main body 5a having the parting surface 5c and the attachment portion 5b to the PL surface 12.

Next, FIG. 10 shows a gap-filling member 6 according to a modified example.
a and the mounting portion 6b are integrally formed of a plastic material such as a hard resin or a metal which shows only a small elastic elongation and shifts to a plastic deformation.

FIG. 10A shows a state in which the mold is opened to finish the gap filling member 6, and the upper surface of the gap filling main body 6a is
It protrudes upward from the general PL surface 12 which is not the recess 46.
Further, the parting surface 6 of the gap filling main body 6a facing the cavity.
c is separated from the cavity surface 13.

FIG. 10 (b) shows a mold clamping operation for finishing the gap filling member 6, and the upper die 21 is used until the upper surface of the gap filling main body 6 a is at the same level as the general PL surface 12. The stuffing body 6a is plastically deformed in the vertical direction, and the PL surface 1
The gap between 2 and 22 is completely eliminated. Further, the gap filling main body 6a is plastically deformed in the horizontal direction by an amount corresponding to the plastic deformation in the vertical direction, and is particularly plastically deformed so that the parting surface 6c protrudes into the cavity 30 toward the cavity.

Then, as shown in FIG. 10 (c), the part protruding into the cavity 30 is scraped off with a file or the like so that the parting surface 6c is substantially flush with the cavity surface 13. The gap filling member 6 is formed by finishing. When the polyurethane material is injected (not shown), the parting surface 6c forms a parting with the polyurethane coating and forms a partial surface of the polyurethane coating.

It should be noted that the present invention is not limited to the above-described embodiment, and may be embodied by appropriately changing the scope of the invention as follows, for example, as follows. (1) A recess 46 and a mounting groove 47 are formed on the PL surface 22 of the upper die 21 and the gap filling members 5 and 6 are mounted. (2) The present invention relates to a molding apparatus for RIM molding products other than polyurethane coating of a steering wheel, and various types of molding other than RIM molding that cause burrs (eg, resin injection molding, rubber transfer). (E.g., molding).

[0042]

Since the molding apparatus of the present invention is configured as described above, burrs are generated due to non-uniform surface pressure on the PL surface, and burrs are generated at locations where it is difficult to close the gap between the PL surfaces. This has an excellent effect of preventing the occurrence of burrs and eliminating or reducing the deburring step after molding.

[Brief description of the drawings]

FIG. 1 is a sectional view of a molding apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III of FIG. 1;

FIG. 4 is an enlarged sectional view taken along the line IV-IV of FIG. 1;

FIG. 5 is an enlarged sectional view of a PL section in FIG. 1;

FIG. 6 is a sectional view taken along line VI-VI of FIG. 1;

FIG. 7 is a cross-sectional view showing an elastic deformation state of the gap filling member of FIG.

FIG. 8 is a sectional view showing a modification of the gap filling member.

FIG. 9 is a sectional view showing another modified example of the gap filling member.

FIG. 10 is a sectional view showing a modified example of the gap filling member.

FIG. 11 is a sectional view of a conventional molding apparatus.

FIG. 12 is a sectional view taken along line XII-XII of FIG. 11;

FIG. 13 is an enlarged sectional view of a PL section in FIG. 11;

FIG. 14 is a sectional view taken along line XIV-XIV of FIG. 11;

FIG. 15 is a partial perspective view showing a part of a polyurethane coating formed on a cored bar.

[Explanation of symbols]

 2 Polyurethane coating 5 Gap-filling member 5a Gap-filling main body 5b Mounting part 5c Parting-off surface 6 Gap-filling member 6a Gap-filling main body 6b Mounting part 6c Parting-off surface 11 Lower mold 12 PL surface 13 Cavity surface 14 Lower mold mounting plate 15 Lower mold Spacer 16 Lower die plate 21 Upper die 22 PL surface 23 Cavity surface 24 Upper die mounting plate 25 Upper die spacer 26 Upper die plate 30 Cavity 31 Polyurethane material 44 Coil spring as elastic body 46 Recess 47 Mounting groove

Claims (5)

[Claims] 1. A molding apparatus in which a mold is composed of at least two split dies, a PL surface and a cavity surface are provided on an inner surface of the split die, and an outer surface of the split die is attached to a die plate via a spacer. In the above, the cross-sectional shape of the spacer is made substantially the same as the shape in which the cavity surface is projected on the outer surface of the split mold so that the surface pressure of the PL surface becomes substantially uniform over the entire circumference of the cavity surface when the split mold is clamped. A molding die apparatus characterized by the above-mentioned. 2. The molding device according to claim 1, wherein an elastic body which does not reach a compression limit unless a force greater than a clamping force of the split mold is applied between the spacer and the die plate or the split mold. Mold device. 3. The molding apparatus according to claim 2, wherein said elastic body is constituted by a plurality of springs arranged at equal intervals. 4. A molding apparatus in which a mold is composed of at least two split molds, and a PL surface and a cavity surface are provided on an inner surface of the split mold, wherein the PL surface of the split mold faces a cavity surface. A recess is formed along the recess, and a gap filling member made of an elastic material having a large elastic elongation is attached to the recess. When the mold is opened, the surface of the gap filling member protrudes from the PL surface, and the gap closing member is closed. The surface is separated from the cavity surface, and at the time of mold clamping, the gap filling member is elastically compressed and deformed by another split mold until the surface of the gap filling member is at the same level as the PL surface, and temporarily A molding die device, wherein a parting surface of the gap filling member is substantially flush with a cavity surface. 5. A molding apparatus in which a mold is composed of at least two split dies, and a PL surface and a cavity surface are provided on an inner surface of the split die, wherein the PL surface of the split die faces a cavity surface. Forming a recess along, attaching a gap-filling member made of a plastic material that transitions to plastic deformation with only a small elastic elongation in the recess, wherein the gap-filling member is a gap-filling member when the mold is opened for finishing. The surface is made to protrude from the PL surface, and during the mold clamping for finishing, the gap-filling member is plastically compression-deformed by the other split mold until the surface of the gap-filling member is at the same level as the PL surface, so that the parting surface of the gap-filling member has a cavity. A molding die apparatus formed so as to protrude inward, and by shaving off the protruding portion so that the parting surface is substantially flush with the cavity surface, the molding die device is formed.