JPH0334453B2 - - Google Patents

Description

Detailed Description of the Invention A. Object of the Invention (1) Industrial Application Field The present invention has an end wall, a side wall connected to the end wall, and an undercut connected to the side wall. The present invention also relates to a molding apparatus for a grained synthetic resin molded body having an undercut for molding a synthetic resin molded body having grained patterns on at least the end walls and side walls from a synthetic resin sheet.

(2) Conventional technology Conventionally, when molding the molded object, a synthetic resin sheet having a grain pattern is sandwiched between a male mold and a female mold to form the molded object, and then The undercut is formed by inserting the slide core into the recess provided in the other mold (Jitsukai Sho.
(See Publication No. 56-160820).

(3) Problems to be Solved by the Invention However, according to the above-mentioned method, there is a problem in that the synthetic resin sheet is stretched during molding of the end walls, side walls and undercut, so the grain pattern becomes blurred and becomes unclear, reducing the commercial value. be.

In addition, the production of the slide core and the recess into which it is inserted requires a lot of work, which increases the cost of the device, and there is also the problem that the parting line between the slide core and the edge of its sliding opening is transferred to the molded product. .

An object of the present invention is to provide the above-mentioned molding method and molding apparatus which can solve the above-mentioned conventional problems.

B. Structure of the Invention (1) Means for Solving the Problems The method for molding a synthetic resin molded article with an undercut according to the present invention includes an end wall, a side wall connected to the end wall, and a side wall connected to the end wall. In molding a synthetic resin molded article from a synthetic resin sheet, the synthetic resin molded body has an undercut connected to the side wall and has a wrinkled pattern on at least the end wall and the side wall. forming the end wall and side wall by applying a method and simultaneously embossing both walls; using a blow molding method and a vacuum forming method together on the unformed portion of the synthetic resin sheet that is connected to the side wall; and forming the undercut.

Further, the method for molding a synthetic resin molded article with a wrinkled undercut according to the present invention includes an end wall, a side wall connected to the end wall, and an undercut connected to the side wall, A molding apparatus for molding a synthetic resin molded body having a wrinkled pattern on at least the end wall and the side wall from a synthetic resin sheet, wherein the end wall and the side wall are molded and at the same time both walls are wrinkled. A first molding comprising a molding part having a grain pattern and countless fine vacuum holes evenly distributed over the grain pattern, and a blow pressure supply part having a blow hole provided in a portion corresponding to the undercut. a mold; a clamping part capable of clamping the synthetic resin sheet in cooperation with the molding part; and a clamping part connected to the clamping part so as to be able to face the blow pressure supply part, and having a plurality of vacuum holes. A second mold having an undercut molding part;

(2) Effects According to the above-mentioned forming method, the end wall of the molded body and the side wall connected thereto are formed and at the same time, both walls are embossed, so that the embossed pattern is clearly formed without running. Furthermore, since the undercut is formed using blow molding and vacuum forming in combination, parting lines are not transferred to the surface of the molded product, and the surface properties of the molded product are good.

Furthermore, since the forming apparatus does not require a slide core for undercut forming, the structure of the apparatus can be simplified and costs can be reduced accordingly.

(3) Embodiment FIG. 1 shows a grained synthetic resin laminate molded body L comprising a core material C of a synthetic resin sheet S and an undercut formed from the core material C, and the molded body L has an end wall w,
A pair of side walls w ₁ connected to both ends of the end wall w,
w ₂ , a shallow undercut u continuous to one side wall w ₁ , and a pair of edges e ₁ and e ₂ continuous to the undercut u and the other side wall w ₂ ; A hazel pattern is formed on the synthetic resin sheet surfaces of w and both side walls w ₁ and w ₂ .

FIG. 2 shows a first embodiment of a molding apparatus for molding the molded article L, and the apparatus includes a first movable part ₁₁ which can be raised and lowered, and a second movable part 12 which can be raised and lowered below the first movable part ₁₁ . It becomes more.

The first movable part ₁₁ is configured as follows.

The downward opening 4 of the box 3 having the top wall 2 is closed by a first mold _{5 1 .}
The outer peripheral edge of is connected to the flange 7 of the box body 3 via the backing plate 6
It is fixed to by a plurality of bolts 8 and nuts 9. A support plate 10 is suspended from the top wall 2 of the box body 3, and intermediate parts of a plurality of angle members 11 are attached to the lower edge of the support plate 10 at predetermined intervals in a plane orthogonal to FIG. Both ends of each angle member 11 are welded to the inner surface of the box body 3. The first mold 5 ₁ is attached to each angle member 11.
It is suspended by a plurality of bolts 13 that pass through and are screwed into the threaded cylinder 12 of the first mold ₅₁ . A vacuum sealing material 14 is interposed between the inner peripheral edge of the flange 7 and the first mold ₅₁ .

As shown in FIGS. 3 and 4, the first mold 5 ₁ is
It is made of a nickel electroformed body, and a grain pattern 15 faithful to cowhide is formed on its lower surface. Also, the first mold 5
₁ , numerous fine vacuum holes 16 are formed so as to be uniformly distributed over the entire grain pattern 15. The opening 1 on the grain pattern 15 side of the vacuum holes 16
6a are arranged at a pitch of about 0.2 mm in the vertical and horizontal directions, and their diameters are 0.03 to 0.05 mm.
As described above, since the opening 16a of the vacuum hole 16 has an extremely small diameter, the grain pattern 15 is not damaged in any way.

The manufacturing of the first mold 5 ₁ consists of a step of making a precision model from cowhide, a step of forming a conductive layer on the cowhide patterned surface of the precision model, that is, a grain patterned surface, and a step of forming polystyrene beads with a diameter of 0.2 mm on the surface of the conductive layer. Laminated in 4 layers,
The process of placing the precision model in the plating liquid layer by putting glass beads in a net or placing an anti-floating body on top of it, forms the plating layer to such an extent and thickness that the upper peripheral surface of the top layer of polystyrene beads is exposed. This is done through an electroforming step in which the spaces between adjacent polystyrene beads are filled with nickel, and a step in which the polystyrene beads are eluted from the nickel electroformed body.

As a result of this elution of the polystyrene beads, an opening 16a is formed at the contact point between the polystyrene beads in the lowermost layer and the conductive layer on the precision model, and a cavity 16 corresponding to the size of the polystyrene beads is formed in the nickel electroformed body.
A communication hole 16c of the adjacent cavity 16b is formed at the contact point between the polystyrene beads and the adjacent polystyrene beads, and an opening 16d is formed at the position where the upper peripheral surface of the outermost polystyrene bead was exposed. A vacuum hole 16 is obtained.

Inside the box body 3, a back-up body 17 having numerous ventilation holes is integrally joined to the back side of the first mold ₅₁ to reinforce the first mold ₅₁ . The back-up body 17 is arranged on the side of the first mold 5 ₁ and partially joins adjacent steel balls made of stainless steel or the like with excellent corrosion resistance using thermosetting synthetic resin such as epoxy resin. The first layer 17 ₁ and
Laminated on the first layer ₁₇₁ is a second layer ₁₇₂ in which numerous adjacent glass beads are partially bonded with the same thermosetting synthetic resin as described above.

When forming the first layer 17 ₁ , a thin resin layer R ₁ made of the thermosetting synthetic resin is placed on the surface of the box body 3 on the back side of the first mold 5 ₁ as shown in FIG. A predetermined amount of steel balls 18 with a diameter of 70 to 150μ is injected, and then steel balls 18 and a resin layer _R1 of 70 to 80μ are injected.
℃ to join the parts of the resin layer R ₁ located at the contact points between adjacent steel balls 18, thereby forming a void V ₁ surrounded by each joining point. This void V ₁ forms a ventilation hole in the first layer 17 ₁ . When the steel balls 18 are bonded to each other, the first layer 17 ₁ and the first mold 5 ₁ are also bonded by the resin layer R ₁ .

In addition, when forming the second layer 17 ₂ , a member (not shown) having the same shape as the recess 17 a is suspended in the box 3 to form the recess 17 a to reduce weight.
As shown in FIG. ₆ , a predetermined amount of glass beads 19 of 400 to 600 μm having the thin resin layer R ₂ on the surface are injected onto the surface of the glass beads 19, and then the glass beads 19 and the resin layer R ₂ are heated to 70 to 80°C. The parts of the resin layer R ₂ located at the contact points between adjacent glass beads 19 are bonded by heating to form a void V ₂ surrounded by each bond point. This void V ₂ forms ventilation holes in the second layer 17 ₂ . When bonding the glass beads 19, the resin R ₂ is also applied between the first layer 17 ₁ and the second layer 17 ₂ .
are respectively joined by.

A plurality of through holes 20 are formed in the support plate 10, and the glass beads 19 are formed through these through holes 20.
The flow is not obstructed by the support plate 20 during injection.

A cooling pipe 21 is embedded in the first layer 17 ₁ in a meandering manner so that the first mold 5 ₁ can be uniformly cooled over the entire area. In this case, the first layer 17 ₁ is mainly composed of the steel balls 18 and has good thermal conductivity, so that the first mold 5 ₁ can be efficiently cooled.
Furthermore, the first layer 17 ₁ is reinforced by embedding the cooling pipe 21 in a meandering manner.

Inside the box body 3, a vacuum pump 2 is connected via a switching valve ₂₂₁ .
3 ₁ and the blower 24 ₁ .

As shown in FIG. 2, the first mold 5 ₁ has blow holes provided in a portion corresponding to a molding part 5 a and an undercut u for molding the end wall w and both side walls w ₁ and w ₂ of the molded body L. Blow pressure supply section 5b having 28
, the blow pressure supply section 5b and the sheet pressing section 5 connected to the forming section 5a on the opposite side.
c, 5c. In this case, the blow hole 28
Since it is formed in the electroforming process, it is composed of numerous fine ventilation holes similar to the vacuum holes 16 of the molded part 5a.

The second movable part ₁₂ is configured as follows.

Upward opening 27 of box body 26 having bottom wall 25
is closed by the second mold ₅₃ . The second mold ₅₂ has a clamping part 5'a which can clamp the synthetic resin sheet S and the core material C in cooperation with the molding part 5a of the first molding mold ₅₁ , and the clamping part 5' an undercut molding part 5'b connected to one side of a so as to face the blow pressure supply part 5b, and the undercut molding part 5'b and the clamping part 5'a being connected to the other side. The sheet holding portions 5'c, 5'c are provided.

Sandwiching part 5'a and undercut molding part 5'b
A plurality of vacuum holes 30 ₁ and 30 ₂ are formed so as to be distributed substantially uniformly throughout the vacuum holes. Further, on the upper surface of the second mold ₅₂ , there is provided a groove for fitting the core material C from the vicinity of the undercut molding part 5'b of one sheet pressing part 5'c to almost the entire area of the clamping part 5'a. A recess 29 is formed. The inside of the box body 26 is connected to a vacuum pump 23 ₂ .

The synthetic resin sheet S may be a single sheet made of polyvinyl chloride or the like, or a laminated sheet in which the sheet is used as a skin layer and a polypropylene foam sheet is laminated thereon as a cushion layer.

In addition, the core material C is formed by forming a plurality of small-diameter vacuum holes 31 in a plate made of ABS resin or the like in correspondence with the vacuum holes 30 ₁ of the sandwiching part 5'a, and using this plate as a second mold 5 ₂ .
A window 32 is formed in a portion corresponding to the undercut molding portion _5'b of the second mold 52.

Next, the molding of the molded body L will be explained.

A hot melt adhesive is applied as an adhesive to the surface of the core material C, and the adhesive is softened by heating.

As shown in FIG. 2, raise the first movable part ₁₁ ,
Further, the second movable part 1 ₂ is lowered to open the first mold 5 ₁ and the second mold 5 ₂ , and the core material C is placed in the recess 29 of the second mold 5 ₂ with its adhesive coated surface facing outward. , and install each vacuum hole 31 toward the second
The vacuum suction holes 30 ₁ of the mold 5 ₂ and the windows 32 are matched with the undercut molding portions 5'b, respectively.

A synthetic resin sheet S consisting of a polyvinyl chloride skin layer a and a polypropylene foam sheet cushion layer b is heated to a high temperature of about 180° C. to soften it, and the synthetic resin sheet S is placed in the first and second layers with the skin layer a facing up. It is arranged between two movable parts 1 ₁ and 1 ₂ .

As shown in FIG. 7, lower the first movable part ₁₁ ,
Further, the second movable part 1 ₁ is raised to move between the molding part 5a of the first mold 5 ₁ and the clamping part 5'a of the second mold 5 ₂ and the sheet holding part 5c of both molds 5 ₁ , 5 ₂ . A synthetic resin sheet S is sandwiched between 5'c.

The inside of the box body 3 of the first movable part 1 ₁ is connected to the vacuum pump 23 ₁ via the switching valve 22 ₁ , and the vacuum pump 2
3 Vacuum the synthetic resin sheet S according to _{step 1} . The molded part 5a has countless fine vacuum holes 16 throughout the molded part 5a, and the synthetic resin sheet S
Since the sheet S is sufficiently blended into the molding part 5a by the clamping part 5'a, the sheet S is tightly adhered to the entire molding part 5a, so that the grain pattern 15 is accurately and clearly formed on the surface of the sheet S. At the same time as the transfer, the sheet S is molded into the shape of the molded portion 5a. Since the first mold 5 ₁ is cooled by the cooling pipe 21,
The surface of the sheet S is immediately cooled and the grain pattern 15 is formed.
is maintained clearly. In this case, synthetic resin sheet S
Since the opposing portion of the undercut molding portion 5'b is also vacuum-suctioned by the blow pressure supply portion 5b of the first mold ₅₁ , the grain pattern 15 is also transferred to this portion.

A semi-molded body having an end wall w and both side walls w ₁ and w ₂ formed from the sheet S by switching the inside of the box 3 of the first mold 5 ₁ to the blower 24 ₁ side via the switching valve 22 ₁ While applying blow pressure to the second movable part 1 ₂
The vacuum pump 23 ₂ on the side is operated to vacuum-suction the semi-molded product to the second mold 5 ₂ side.

As a result, the semi-molded body is released from the first mold 5 ₁ and is brought into close contact with the core material C and integrally joined thereto. Since the semi-molded body is tightly adhered to the first mold 5 ₁ , the combination of the vacuum suction action and the blow pressure is an extremely effective means for promoting release of the molded body.

In addition, by combining the blow pressure in the blow pressure supply section 5b and the vacuum suction pressure in the undercut forming section 5'b, the undercut forming section 5'b is connected to the one side wall _w1 of the synthetic resin sheet S. The opposing unformed portions come into close contact with the undercut forming portion 5'b through the window 32 of the core material C, thereby forming the undercut u.

The blower 24 ₁ is stopped, and the inside of the box 26 of the second movable part 1 ₂ is switched to the atmosphere, and then the first movable part 1 _{1 is} switched to the atmosphere.
is raised and the second movable part 1 ₂ is lowered to remove the molded body L from the second mold 5 ₂ . This molded body L
The portion of the core material C facing the window 32 is cut away.

On the surfaces of the end wall w, side walls w ₁ , w ₂ and undercut u of this molded body L, the grain pattern 15, which is the same as the skin pattern of the cowhide, is clearly transferred without running, and the cushion layer b and the core The bonding strength with material C is also high and the durability is excellent. Furthermore, since the undercut U is formed by a combination of blow molding and vacuum forming, the surface quality of that part is good. This type of molded product L is suitable for automobile instrument panels, interior materials, and the like.

8 to 10 show second to fourth embodiments of the present invention, and in these embodiments, the second mold 5 ₂
The undercut molding portion 5'b is formed deeply,
In response to this, various efforts have been made to increase the blow pressure.

In the second embodiment shown in FIG.
The inner surface of the box body 3 of _{No. 1} and the partition wall 33 provided inside the box body 3 define an air chamber 34 located on the back side of the blow pressure supply section 5b and surrounding the blow hole 28. A vacuum pump 23 ₃ and a blower 24 2 are connected through a switching valve 22 2 to the vacuum pump 23 ₃ and a blower 24 ₂ . The other configurations are the same as those of the first embodiment.

The vacuum pump 23 ₃ is made of synthetic resin sheet S.
It is used to emboss the part facing the undercut forming part 5'b.

The third embodiment shown in FIG. 9 is a modification of the second embodiment, in which each blow hole 28 is formed with a large diameter, and the steel balls 18 constituting the backup body 17 in the air hole 34 have a large diameter. The ventilation holes were made larger using the same material. Each blow hole 28 is formed to have a large diameter in an electroforming process.

The fourth embodiment shown in FIG. 10 is a blow pressure supply section 5b.
A vent pipe 35 having a blow hole 28 is provided on the back side of the vent pipe 35, and the switching valve 22 is installed in the vent pipe 35 as described above.
A vacuum pump 23 ₃ and a blower 24 ₂ are connected via ₂ .

The present invention is also applicable to the case where the end wall w and one of the side walls w ₁ and w ₂ of the molded body L are subjected to chiseling.

C. Effects of the Invention According to the molding method of the present invention, the end wall of the molded body and the side wall connected to the end wall are molded, and at the same time, the embossment is applied to both walls, so the grain pattern is clearly defined without flowing. can be formed into Furthermore, since the undercut is formed using both blow molding and vacuum forming, parting lines are not transferred to the surface of the molded product, and the surface properties of the molded product are good.

Further, according to the molding apparatus of the present invention, a conventional slide core is not required for undercut molding, so that the structure of the apparatus can be simplified and costs can be reduced accordingly.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a molded body obtained by the present invention, FIG. 2 is a longitudinal sectional view of a first embodiment of a molding apparatus,
Figure 3 is a partial plan view of the first mold, and Figure 4 is a partial plan view of the third mold.
Fig. 5 is a sectional view of a part of the first layer in the back-up body, Fig. 6 is a sectional view of a part of the second layer in the back-up body, and Fig. 7 shows the graining and forming process. FIGS. 8, 9, and 10 are vertical cross-sectional views of main parts of second, third, and fourth embodiments of the molding apparatus. L...Molded body, S...Synthetic resin sheet, u...
Undercut, w... End wall, w ₁ ... Side wall, 5
₁ , 5 ₂ ... first and second molds, 5a ... molding section,
5b... Blow pressure supply part, 5'a... Sandwiching part,
5'b...Undercut forming part, 28...Blow hole, ₃₀₂ ...Vacuum hole.

Claims (1)

[Scope of Claims] 1. A synthetic resin comprising an end wall, a side wall connected to the end wall, and an undercut connected to the side wall, and at least the end wall and the side wall have a wrinkled pattern. When molding a molded object from a synthetic resin sheet,
applying a vacuum forming method to the synthetic resin sheet that has been heated to a high temperature to form the end wall and side wall and simultaneously embossing both walls; an unformed portion of the synthetic resin sheet that is connected to the side wall; A method for molding a grained synthetic resin molded article having an undercut, comprising: molding the undercut using a blow molding method and a vacuum molding method in combination; 2 A synthetic resin molded article having an end wall, a side wall connected to the end wall, and an undercut connected to the side wall, and having a wrinkled pattern on at least the end wall and the side wall, is formed into a synthetic resin sheet. In order to form the end wall and the side wall and simultaneously emboss both walls, the embossed pattern and numerous fine vacuum holes uniformly distributed over the entire embossed pattern are formed. a first mold comprising a molding part having a blow pressure supply part having a blow hole provided in a part corresponding to the undercut;
A clamping part that can clamp the synthetic resin sheet in cooperation with the molding part, and an undercut molding that is connected to the clamping part so as to be able to face the blow pressure supply part and has a plurality of vacuum holes. A molding device for a grained synthetic resin molded article, comprising: a second mold having a second mold; and an undercut comprising; 3. The undercut according to claim 2, wherein the blow holes of the blow pressure supply section in the first molding die are composed of numerous fine ventilation holes similar to the vacuum holes of the molding section. A molding device for synthetic resin molded bodies with grains. 4. The undercut according to claim 2, wherein the blow hole of the blow pressure supply part in the first molding die is constituted by a plurality of vent holes having a larger diameter than the vacuum hole of the molding part. A molding device for synthetic resin molded bodies with grains. 5 The blow pressure supply section in the first mold is:
5. A molding device for a grained synthetic resin molded article having an undercut according to claim 2, wherein the back surface thereof is provided with an air chamber surrounding the blow hole. 6. Claim 5, wherein the first mold is provided with a reinforcing back-up body having a ventilation hole on its back surface, and the ventilation hole is roughly formed in a portion of the back-up body that exists in the air chamber. A molding device for a grained synthetic resin molded article having the undercut described above. 7. The grained synthetic resin molded article with an undercut according to claim 2, wherein the blow pressure supply part in the first mold is equipped with a ventilation pipe having the blow holes on its back surface. Molding equipment.