JP2000000830A - Preparation of metal mold for molding synthetic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an anchor part from generating a cut when a metal mold which is provided with a mold main body made of a cast iron casting and a mold face constituting body formed by applying a flame spray processing on the mold main body and for providing a shape to a synthetic resin material and with good thermal conductivity and wherein the mold face constituting body has a recessed shape main body provided with a molding face and an anchor part for preventing the recessed shape main body from releasing, is prepd. SOLUTION: A process wherein a recessed shape main body 23 is formed by applying a plasma flame spray coating on a region 29a corresponding to the recessed shape main body in a molding face constituting body forming region 29 in a mold main body 1a, a process wherein a high density and high strength padding part 301 fused with the end edge part 23a of the recessed shape main body 23 is formed by applying plasma transfer arc welding processing to an anchor part corresponding region 27 of the region 29 and a process wherein an anchor part 26 is formed by applying mechanical processing to the padding part 301, are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for manufacturing a synthetic resin molding die.

[0002]

2. Description of the Related Art Conventionally, injection molding dies, for example, are JIS
It is made of carbon steel for machine structure such as S45C.

[0003]

However, when the dies are made of the carbon steel, their heat conductivity is relatively low and the cooling performance is poor, so that the cycle time of the molding operation becomes long and the weight of both dies is reduced. Due to the large size, there is a problem that the workability of assembling and removing them from the apparatus main body is poor.

Therefore, the present inventors have first made it possible to improve the production efficiency of molded products by shortening the cycle time of the molding operation, and to achieve the weight reduction easily and the relatively inexpensive synthesis method. As a resin molding die, a mold main body that is a cast iron casting, formed by performing a thermal spray treatment on the mold main body, and provided with a molded surface component having good thermal conductivity to impart a shape to the synthetic resin material, The molding surface structure includes a concave main body having a molding surface, and an anchor portion formed on the opening side of the concave main body so as to be bent outward to prevent peeling of the concave main body. We have developed what we have.

However, when the forming surface structure is subjected to grinding in the finishing step of the mold, chipping is likely to occur at the outer edge portion of the anchor portion or at the corner of the concave main body opposite to the anchor portion. A manufacturing problem has arisen.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a manufacturing method capable of obtaining a mold having a sound forming surface structure without chipping.

[0007] To achieve the above object, according to the present invention,
A mold body that is a cast iron casting, and a mold surface structure formed by performing a thermal spray treatment on the mold body, and having a good thermal conductivity forming surface to impart a shape to the synthetic resin material, the molding surface structure,
A concave main body with a molding surface, and on the opening side of the concave main body,
In manufacturing a mold having an anchor portion formed so as to be bent outward and preventing peeling of the concave main body,
Casting the mold body using cast iron, performing a pre-spraying process on a molding surface structure forming region of the mold body, and performing a plasma spraying process on the concave main body corresponding region of the molding surface structure forming region. Forming the concave main body, and performing a plasma transfer arc welding process on an area corresponding to the anchor portion of the forming surface structure forming area to form a built-up portion fused with the edge of the concave main body. A method for manufacturing a synthetic resin molding die is provided, which includes a step and a step of forming the anchor portion by machining the overlaid portion.

Although the main part of the concave shape formed by the plasma spraying process is a laminated structure, the plasma transfer arc welding process (P
TA) the overlaid portion is metallurgically uniform,
It is integrated with the mold body. Therefore, the built-up portion has a stronger adhesive force to the mold body than the concave main body, and has a high density and high strength. Moreover, the built-up portion fuses with and takes in the edge portion of the concave main body.

Such a built-up portion sufficiently withstands machining such as cutting and grinding, so that an anchor portion having no chip in the outer edge portion can be formed. Further, since the corner portion mainly composed of the concave portion is present at the edge portion incorporated in the overlay portion, the corner portion is not chipped when forming the corner portion.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIGS. 1, 2 and 7, a stationary die 1 and a stationary die 1 as a synthetic resin molding die are shown.
The movable mold 2 which can move forward and backward is used for injection molding of a synthetic resin bumper for automobiles.

As clearly shown in FIGS. 1 to 6, the mating surfaces 3 of the fixed mold 1 are located at opposing positions and have a pair of flat surfaces 4 which intersect with the moving direction 2 of the movable mold 2. And a concave surface 5 in the form of a strip having both ends connected to both flat surfaces 4. A channel 6 extending from one flat surface 4 to the other flat surface 4 via the concave surface 5 to the other flat surface 4 is formed in the mating surface 3 in a U-shape, and the inner surface of the channel 6 forming a concave cross section is
It functions as a concave forming surface 7 that gives a shape to the synthetic resin material. A gate 8 is formed in the fixed mold 1 so as to open at the bottom of the molding surface 7. A positioning ridge 9 is formed outside each flat surface 4, and a flat surface 10 outside each positioning ridge 9 is formed.
Then, a positioning pin hole 11 is opened.

As clearly shown in FIGS.
The mating surfaces 12 of the fixed dies 1
A pair of flat surfaces 13 ₁ that matches the inner side of both the flat surfaces 4 are connected both flat surfaces 13 ₁ on both ends, respectively, convex shape surface 14 which forms a band shape and matches the concave surface 5 of the stationary die 1 and Consisting of The Totsukatachimen 14, projections 15 extending on the other flat surface 13 ₁ side from one of the flat surfaces 13 ₁ side is bent formed into a U-shape, and both end faces 15a and both flat surfaces 13 ₁ of the projections 15 A predetermined interval is provided between them. The surface of the ridge 15 and the base of the ridge 15 in the convex surface 14 are:
A convex forming surface 16 corresponding to the concave forming surface 7 of the fixed mold 1 is formed. The outside of each planar surface 13 _1, the positioning concave 17 is formed to conform to the positioning projections 9 of the stationary mold 1, also from the outside of the flat surface 13 ₂ of the positioning concave 17, the stationary die 1 A positioning pin 18 that matches each positioning pin hole 9 protrudes. Both positioning concave 17 both flat surfaces 13 ₁ of the inner, are formed by a slide core s provided in the mold body 2a.

As clearly shown in FIGS. 2 to 4, when the mold is clamped, the bump-forming cavity is formed by the cooperation of the convex forming surface 16 of the movable mold 2 and the concave forming surface 7 of the fixed mold 1. C is formed.

The fixed mold 1 is a mold body 1a which is a cast iron casting.
And a molding surface component 20 having good thermal conductivity formed by subjecting the mold body 1a to a thermal spraying process and having a concave-formed surface 7.
And As clearly shown in FIGS. 1, 5 and 6, the molding surface arrangement 20 has a channel-shaped main body 23 as a concave main body having a concave-formed surface 7. The open side of the main body 23, that is, the outer edge b of the U-shaped end face 24 existing on both flat surfaces 4 and the outer edge b of the both end faces 25 present on the concave surface 5 and parallel to each other are bent outward. An anchor portion 26 having a substantially flange shape is formed endlessly. The anchor part 26
Has an effect of attaching the main body 23 to the mold body 1a by adhering to the endless recess 27 recessed from the flat surface 4 and the concave surface 5. The channel-type main body 23 is composed of an underlayer 21 made of a Ni-Al-based alloy and a surface layer 22 on the underlayer 21 and made of a Cu-based alloy, as shown in FIGS. The anchor portion 26 is made of the same Cu-based alloy as the surface layer 22.

In manufacturing the fixed mold 1, the following method is adopted.

(1) As shown in FIG. 8A, the mold body 1a is cast using cast iron. Gray cast iron, spheroidal graphite cast iron, or the like is used as the cast iron.

(2) As shown in FIG. 8 (b), a pre-spraying process is performed on the forming surface structure forming region 29 of the mold body 1a.
This processing includes scalping, grinding in consideration of the thickness of the molding surface structure 20, formation of the endless recess 27, and the like, and sandblasting for roughening.

(3) As shown in FIG. 8 (c), a channel-shaped (concave) main body corresponding area 29a of the forming surface structure forming area 29 is subjected to plasma spraying using a Ni-Al alloy to form a pole. 9 is formed.
As shown in (a), a thick surface layer 22 is formed by subjecting the surface of the underlayer 21 to plasma spraying using a Cu-based alloy.
Is formed to obtain a channel-shaped main body 23.

As the Ni—Al alloy, Ni-5 wt.
% Al alloy, Ni-20wt% Cr alloy, Ni-7wt
% Al-8wt% Cr-5wt% Fe-5wt% Mo alloy or the like is used, and as a Cu-based alloy, Cu-15.5 is used.
wt% Ni-0.71wt% B-2.63wt% Si alloy, Cu-38wt% Ni alloy, Cu-10wt% Al
-5wt% Ni alloy, Cu-10wt% Al-1wt%
Fe alloy, Cu-9.1 wt% Al-3.8 wt% Fe
-2.1 wt% Ni-1 wt% Mn alloy or the like is used.

(4) As shown in FIG. 9 (b), a plasma transfer arc welding process using the same Cu-based alloy as described above is applied to the area corresponding to the anchor portion of the forming surface structure forming area 29, that is, the endless concave portion 27. forming the built-up portion 30 ₁ fused to the edge of the channel-shaped main body 23 is subjected to.

(5) As shown in FIG.
_An excess portion is removed by performing a cutting process on ₁ to form an anchor portion 26, and then a finishing process is performed on the entire molded surface structure 20 by grinding.

Necessary machining such as formation of the positioning pin hole 11 is performed in, for example, the above-mentioned step (2) or (5), and finally, various components are assembled.

In the fixed mold 1, when the molding surface constituting body 20 is made of a Cu-based alloy or a Ni-Al-based alloy, the heat conductivity of the concave-formed surface 7 and its vicinity is relatively high, and the cooling performance is good. Therefore, the cycle time of the molding operation can be shortened, and the production efficiency of the bumper can be improved.

The mold body 1a is a cast iron casting, and pinholes may appear on its surface. The pinholes are covered with the molding surface structure 20, and the surface of the molding surface structure 20 Because it is easy to smooth,
The surface condition of the bumper is also excellent.

Further, the molding surface structure 2 for the mold body 1a
0 is good and the temperature of the mold body 1a is 200
Even if the temperature exceeds ℃, the molding surface constituting body 20 does not peel off from the mold body 1a.

Further, since the mold body 1a is a cast iron casting, a plurality of hollow portions 28 are provided so as not to impair its strength.
The weight reduction can be easily achieved, and the cost of the fixed mold 1 is relatively low.

When the above-described means is employed in the manufacture of the fixed mold 1, a mold body 1a having a shape close to a finished product can be obtained by casting. The number of processing steps is drastically reduced, the lead time is greatly reduced, and the production cost of the fixed mold 1 can be reduced.

[0028] While the channel-shaped main 23 by plasma thermal spraying has a laminated structure, the deposition unit 30 ₁ by plasma transfer arc welding process together fused to the mold body 1a a metallurgically uniform tissue I have. Therefore the deposition unit 30 ₁ has a strong adhesion to the mold body 1a than channel shaped main 23, also the density is also high strength. Moreover, the built-up portion 30 ₁ is fused to the edge portion 23a of the channel shaped main 23 as shown in FIG. 9, which is captures and it.

[0029] Since such padding unit 30 ₁ is sufficiently withstand the cutting can be formed in FIG. 6, the anchor portion 26 with no chipping at the outer edge portion 26a. In addition, since the corner 23b of the channel-shaped main body 23 is present at the edge 23a which is taken into the overlay portion 31 ₁ ,
In forming the corner portion 23b, no chipping occurs.

As shown in FIG. 10, the mold body 2a of the movable mold 2 is also cast using the same cast iron as described above. After being subjected to machining and polishing, the mold body 2a is assembled with various components and used. Thus, the molding surface structure 20 is not used for the movable mold 2. This is because the convex forming surface 16 of the movable mold 20 forms an invisible inner surface side of the bumper.

Next, a specific example of manufacturing the fixed mold 1 will be described.

(A) The mold body 1a is made of spheroidal graphite cast iron (JI
S FCD600), and then mold body 1a
The above-mentioned pre-spray processing was applied to the forming surface structure forming region 29 of FIG. Two such mold bodies 1a were prepared.

(B) In the channel-shaped main body corresponding area 29a of the molding surface structure forming area 29 in each mold body 1a,
A plasma spraying process using a Ni-5 wt% Al alloy powder having a particle size of 45 to 106 μm was performed to form an underlayer 21 having a thickness of about 100 μm.

As the spraying machine, a gun type plasma spraying machine (SG-100 manufactured by Miller Thermal Co., Ltd.) was used.
This was similarly used for forming a surface layer 22 described later. The spraying conditions were as follows: current: 800 A; working gas: Ar pressure 0.35 MPa, He pressure 0.7 MPa; carrier gas:
The Ar pressure was set to 0.28 MPa;

Next, a Cu-10 wt% Al-5w having a particle size of 10 to 90 μm is formed on the underlayer 21 of one mold body 1a.
Plasma spraying using t% Ni alloy powder
A surface layer 22 having a thickness of about 1.5 mm was formed. Thermal spraying conditions are
Current: 750 A; Working gas: Ar pressure 0.35 MPa, H
e pressure 0.75 MPa; carrier gas: Ar pressure 0.35 M
Pa ;.

(C) In the endless concave portion 27 of the mold body 1a,
Cu-10wt% Al-5wt with particle size of 45-105μm
A plasma transfer arc welding process using a Ni alloy powder is performed, and the overlaid portion 30 having the same composition as the surface layer 22 is formed.
Formed _one .

As a welding device, a plasma transfer arc welding device (Utronic Gap System 375, manufactured by Utech Japan Co., Ltd.) was used. This was used in the formation of the built-up portion 30 ₁ which will be described later. Spraying conditions were as follows: current: 100 A; pilot gas: Ar 0.5 L / min
Shielding gas: Ar + 7% H ₂ 15 L / min; carrier gas: Ar ₂ L / min.

The (d) The applying cutting to the padding unit 30 _1, and then subjected to finishing the entire forming surface construction 20.

As another stationary mold 1, a C layer having a particle diameter of 10 to 90 μm is formed on the underlayer 21 of another mold body 1 a under the same spraying conditions for forming the surface layer in the step (b).
u-15.5 wt% Ni-0.71 wt% B-2.63
A plasma spraying process using a wt% Si alloy powder was performed to form a surface layer 22 having a thickness of about 1.5 mm.

Next, in the endless concave portion 27 of the mold main body 1a, the particle size of 45 to 10
5 μm Cu-15.5wt% Ni-0.71wt% B
Subjected to plasma transfer arc welding process using the -2.63wt% Si alloy powder, thereby forming a built-up portion 30 _first surface layer 22 and the same composition.

[0041] then subjected to cutting to padding portion 30 _1, and then subjected to finishing the entire forming surface construction 20.

When the presence / absence of the chip was examined with respect to the molding surface constituting body 20 of both the fixed dies 1, it was found that there was no such chip.

Thereafter, injection molding was performed using each fixed mold 1 and the movable mold 2, and a bumper having a smooth outer surface for each fixed mold 1 was obtained. The injection molding conditions were as follows: molding material: polypropylene (trade name: SP850, manufactured by Idemitsu Petrochemical Co., Ltd.), mold clamping pressure: 45 MPa; injection pressure: 100 MPa; mold temperature: 40 ° C .; molding material temperature: 20
It was set to 0 ° C.

When the gate 8 is formed by making a hole in the bottom 23c of the channel-shaped main body 23, FIG.
As shown in FIG. 12, the plasma transfer arc welding process is performed on the gate forming portion A of the bottom portion 23c to form the gate 8.
To include opening edge 8a of forming an annular padding portion 30 _2.

This makes it possible to prevent the gate opening edge 8a from being chipped due to the drilling process. Overlay 3
0 ₂ after boring, scraped away.

The graining of the Cu-based alloy surface layer 22 of the fixed mold 1 is performed by the following method.

(1) As shown in FIG. 13A, a resin layer 32 made of an uncured acrylic photocurable resin is formed on the surface layer 22 by coating.

(2) As shown in FIG. 13B, a screen 33 on which a large number of small circular portions d are masked is placed on the resin layer 32.

(3) As shown in FIG. 13C, light L is applied to the resin layer 32 through the screen 33. As a result, in the resin layer 32, the portion e that has been irradiated with light is cured and adheres to the surface layer 22, while the portion f that has not been irradiated with light is kept uncured.

(4) As shown in FIG. 13D, the resin layer 32 is subjected to a cleaning process to wash away the uncured photocurable resin. Thereby, on the surface layer 22, the resin layer 32 having a large number of minute holes g corresponding to the large number of minute circular portions d is left.

(5) As shown in FIG. 13E, the surface layer 22 and the resin layer 32 are immersed in an etching solution 34 containing ferric chloride.

(6) As shown in FIG. 14A, a concave portion 35 is formed in a portion of the surface layer 22 corresponding to each minute hole portion g.
To form

(7) As shown in FIGS. 14 (b) to 14 (d), the steps of FIGS. 13 (a) to 13 (e) are defined as one cycle, and this cycle is further performed for three cycles. The inner diameter of the portion g is reduced, thereby gradually increasing the depth of the concave portion 35 by etching, thereby obtaining a conical concave portion 35 as shown in FIG.

It is to be noted that, if necessary, the molding surface structure 20 is also provided on the movable mold 2. The mold is naturally applied to molding methods other than the injection molding method.

[0055]

According to the present invention, there is provided a manufacturing method capable of obtaining a synthetic resin molding die having a sound molding surface structure without any chipping by employing the above means. can do.

[Brief description of the drawings]

FIG. 1 is a perspective view of a fixed mold.

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

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is an enlarged sectional view of a main part at the time of mold clamping.

FIG. 5 is a perspective view showing a relationship between a mold body and a molding surface structure in a fixed mold.

FIG. 6 is an enlarged view of a main part of FIG. 2;

FIG. 7 is a sectional view of a movable mold.

FIG. 8 is an explanatory view showing a first stage of a manufacturing process of the fixed mold.

FIG. 9 is an explanatory view showing a latter stage of the manufacturing process of the fixed mold.

FIG. 10 is a sectional view of a movable mold body.

FIG. 11 is an explanatory diagram of a gate forming method.

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

FIG. 13 is an explanatory diagram of a graining method for a surface layer.

FIG. 14 is an explanatory diagram of a recess forming process by graining.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fixed mold (mold for synthetic resin molding) 1a Mold main body 7 Concave forming surface (molding surface) 8 Gate 20 Molding surface structure 23 Channel-shaped main body (concave main body) 23a Edge 26 Anchor 27 Endless Depressed portion (anchor portion corresponding region) 29 Molded surface structure forming region 29a Channel-shaped main body corresponding region (concave main body corresponding region) 30 ₁ , 30 ₂ Overlay portion A Gate-forming portion

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] May 24, 1999 (1999.5.2
4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

As the Ni—Al alloy, Ni-5 wt.
% Al alloy , Ni-7wt% Al-8wt% Cr-5w
t% Fe-5wt% Mo alloy or the like is used, and as a Cu-based alloy, Cu-15.5wt% Ni-0.71wt%
B-2.63 wt% Si alloy, Cu-38 wt% Ni alloy, Cu-10 wt% Al-5 wt% Ni alloy, Cu-
10wt% Al-1wt% Fe alloy, Cu-9.1wt
% Al-3.8wt% Fe-2.1wt% Ni-1wt
% Mn alloy or the like is used. The underlayer 21 is made of Ni-
It can be formed using 20wt% Cr alloy powder.
is there.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0037

[Correction method] Change

[Correction contents]

As a welding device, a plasma transfer arc welding device (Utronic Gap System 375, manufactured by Utech Japan Co., Ltd.) was used. This was used in the formation of the built-up portion 30 ₁ which will be described later. The welding conditions were: current: 100 A; pilot gas: Ar 0.5 L / min
Shielding gas: Ar + 7% H ₂ 15 L / min; carrier gas: Ar ₂ L / min.

[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yuji Koyama 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd. F term (reference) 4F202 AH24 AJ02 AJ12 CA11 CB01 CD14 CK41 CL02 4K031 AA03 BA08 CB26 CB35 DA04 FA13

Claims (2)

[Claims] 1. A mold body (1a), which is a cast iron casting, and a molded surface component having good thermal conductivity formed by subjecting the mold body (1a) to thermal spraying and imparting a shape to a synthetic resin material. (20), and the molding surface structure (20) is bent outward to a concave main body (23) having a molding surface (7) and an opening side of the concave main body (23). Casting a mold body (1a) using cast iron to manufacture a mold having an anchor portion (26) formed as described above and preventing the concave main body (23) from peeling off; Performing a pre-spray process on the forming surface structure forming region (29) of the mold body (1a); and performing a plasma spraying process on the concave main body corresponding area (29a) of the forming surface structure forming region (29). Forming the concave main body (23) by applying a force to the molding surface structure forming region (29). The overlaid portion (3) fused to the edge portion (23a) of the concave main body (23) by performing plasma transfer arc welding on the portion corresponding to the recessed portion (27).
0 ₁ ) and a step of machining the overlaid portion (30 ₁ ) to form the anchor portion (26). . 2. When forming a gate (8) by making a hole in the concave main body (23), the concave main body (2) is formed.
_{2. The} method for manufacturing a synthetic resin molding die according to claim 1, wherein the plasma transfer arc welding process is performed on the gate-forming portion (A) of ( ₃ ) to form a built-up portion (30 ₂ ).