JP3174635B2 - Mold for casting - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of the prior application of the applicant of the present invention (Japanese Patent Application No. 2-108221), in which a resin material is injected and a mold is clamped by a vacuum suction force. The present invention relates to a molding die for casting.

[0002]

2. Description of the Prior Art The prior application of the present invention relates to the inefficient use of thin and large fiber-reinforced plastic products, such as bathtubs and automobile bodies, as in conventional hand lay-up or spray-up methods. In addition to the unsanitary molding method exposed to harmful steam and the uneconomical molding method that causes a lot of cutting loss of the mat, such as the SMC molding method that press-molds a fiber mat impregnated with a resin raw material, By using a split mold that can be closed in an airtight manner, the injection and filling of the resin material and the mold clamping can be performed using the vacuum suction force, so that the disadvantages of the conventional method described above are almost eliminated, and the mold clamping can be easily performed. The present invention is characterized by providing a cast molding method and a molding die. FIGS. 5 and 6 illustrate the structure of the molding die and the molding method. Reference numeral 50 denotes a molding die, which is a rigid lower die 50A and a flexible upper die 5A.
0B, and the air in the annular seal gap 61 of the pressure reducing seal portion 60 provided on the thick peripheral portion of the lower mold 50A is sucked by the pressure reducing device 70 through the mold clamping negative pressure pipe 71, The mold is clamped by the pressure difference between the reduced annular seal gap 61 and the atmosphere. Reference numeral 62 denotes a reinforcing material embedded in the periphery of the mold. In addition, a vacuum suction groove 52 communicating with the molding cavity 51 is formed around the periphery of a molding cavity 51 for molding a panel-shaped product.
Is connected to a pressure reducing device 70 through a suction negative pressure pipe 72,
By sucking the air in the molding cavity 51,
The injection of resin raw materials and the degassing are performed. Then, the upper mold 50B, which is rich in flexibility, temporarily swells due to the injection pressure of the resin raw material, thereby increasing the volume of the molding cavity 51, speeding up the injection, and lowering the mold clamping pressure and the injection pressure. I am doing it. Numeral 80 denotes a raw material supply unit which mixes an uncured liquid resin raw material and its hardener at a predetermined ratio, discharges a predetermined amount, and feeds the upper mold 50B through a raw material pipe 81.
Is supplied to the injection port 53 provided in the. Reference numeral 90 denotes a resin trap, which is interposed in the suction negative pressure pipe 72 and plays a role of capturing excess resin raw material overflowing from the mold 50. The operation of the casting apparatus is such that when the molding cavity 51 of the lower mold 50A is laid with glass fiber, the upper mold 50B is covered, and the pressure reducing device 70 is operated, the molding mold 50 is clamped as described above. . On the other hand, the resin raw material discharged from the raw material supply unit 80 is decompressed and quickly injected into the molding cavity 51. When the injection port 53 is closed after the injection of the resin material, the swelled upper mold 50B gradually returns to the original mold by the atmospheric pressure and the vacuum suction force, and the filling of the molding cavity 51 with the resin material is completed. Thereafter, the molded product is taken out after the resin material is cured.

[0003]

As described above, the molding die 50 is used.
In the method in which the mold is clamped by the pressure difference between the depressurized annular seal gap 61 of the pressure reduction seal portion 60 provided in the above and the atmospheric pressure, the pressure difference cannot be increased to 1 atm or more. The larger the size, the larger the total area of the annular seal gap 4A must be to secure the required total mold clamping pressure. For example, it is shaped like a tray and the area of the bottom is about 1m ×
In the case of a molded product having a size of 1 m square, the width D1 of the pressure reducing seal portion 60 extending around the periphery of the mold 50 (see FIG. 6).
Is required to be about 30 cm, and the floor area occupied by the molding die 50 is almost twice as large as the bottom area of the molded product, and is close to 2 m ² . As a result, in a cast molding factory where the use efficiency of the working floor surface was originally low, not only the floor area occupied by the molding die increased, but also because the molding die became larger, extra labor was required and productivity was increased. Will be reduced. Furthermore, it is necessary to provide a reinforcing structure to the wide pressure reducing seal portion 60 to prevent deformation, which requires a skilled mold manufacturing technique, extra materials, and prolongs the mold manufacturing time. The momentum was forced to soar. Therefore, an object of the present invention is to perform injection of a resin raw material and mold clamping by a vacuum suction force, and to provide a reduced pressure seal portion in a case where a reduced pressure seal portion is provided around a mold mating surface. By changing the method, it is possible to significantly reduce the floor area occupied by the molding die as compared with the prior invention, and to provide a molding die for cast molding that can be made more easily and at lower cost. is there.

[0004]

In order to achieve the above object, a casting mold for casting according to the present invention fills a molding cavity with a liquid resin raw material by utilizing a vacuum suction force.
In addition, the mold is clamped, and a depressurizing seal portion for mold clamping is provided around a mold-matching surface. The depressurizing seal portion 4 includes an outer peripheral surface 2c of the lower die 2 and an upper die. An annular seal gap 4A is formed between the peripheral seal 3 and a hanging peripheral wall 3c provided by extending the peripheral edge of the seal 3 downward, and the vertical width Y thereof is larger than the horizontal width X.
And annular packings 5 and 6 provided around the lower mold 2 or the upper mold 3 to hermetically seal the annular seal gap 4A. The molding cavity S
Are provided with suction ports 10 and 11 for connecting the annular seal gap 4A and the suction port 7 to a decompression device 50, respectively, and an injection port 9 for a resin raw material into the molding cavity S. Configuration. And lower mold 2
Is preferably made of a rigid material, and the upper mold 3 is preferably made of a flexible material.

[0005]

When the upper mold 3 is put on the lower mold 2 to clamp the mold, the lower mold 2
An annular seal gap 4A is formed between the outer peripheral surface 2c of the upper mold 3 and the hanging peripheral wall 3c of the upper mold 3, and the annular seal gap 4A is formed by annular packings 5 and 6 provided around the lower mold 2 or the upper mold 3. Are hermetically sealed. Then, when the suction port 7 communicating with the molding cavity S and the annular seal gap 4A are connected to the decompression device 70, respectively, the molding dies 1A, 1B
Is securely clamped by the pressure difference between the reduced annular seal gap 4A and the atmosphere, and the pressure inside the molding cavity S is reduced. If the resin material is injected from the injection port 9 in this state, even the narrow molding cavity S is quickly filled without bubbles remaining. Annular seal gap 4A of decompression seal part 4
By making the vertical width Y larger than the horizontal width X, the floor area occupied by the molding dies 1A and 1B is significantly reduced as compared with the molding dies of the prior application, and during the long curing wait time of the resin raw material, It is possible to remarkably reduce a wasteful work floor area for leaving a large number of molds unattended. In addition, if the upper mold 3 is made of a flexible material, the upper mold 3 temporarily swells due to the injection pressure of the resin raw material, so that a low mold clamping pressure and injection pressure are sufficient.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 by taking an example of forming a tray-shaped product made of glass fiber reinforced plastic (FRP). . The bottom of this product has a square shape of about 1m x 1m. The molding die 1A of this embodiment is composed of a lower die 2 and an upper die 3 as shown in FIG. 1, and a vacuum suction force is applied to an outer peripheral portion thereof as shown in FIG. A pressure reducing seal portion 4 for clamping the mold is provided around the periphery.

The lower mold 2 has a tray shape as a whole,
The peripheral wall portion is formed thick. The upper portion of the inner peripheral surface 2a of the peripheral wall portion and the top surface 2b serve as mold matching surfaces with the upper mold 3, respectively. Below the outer peripheral surface 2c of the peripheral wall portion, an annular packing 5 in the shape of an annular plate is horizontally protruded outward. Another annular packing 6 is fitted in a packing groove provided on the top surface 2b. Further, the upper edge of the inner peripheral surface 2a is formed as a chamfered slope 2d.

The upper mold 3 has a shape that can be covered by the lower mold 2 just like a lid of a box. The upper mold 3 has a recessed portion 3 to be dropped inside the tray-shaped lower mold 2.
a is formed. Further, a hanging peripheral wall 3c is suspended from the periphery of the top surface 3b. Mold cavity S of mold 1A
2 is formed between the lower half of the inner surface of the recess 3a of the upper die 3 and the lower half of the inner surface of the lower die 2 as shown in FIG. Then, the lower surface of the top surface 3b and the recessed portion 3
The upper half portion of the outer peripheral surface 3d of “a” is a mold matching surface with the lower mold 2.

When the molding die 1A is closed as shown in FIG. 2, the outer peripheral surface 2c of the lower die 2, the hanging peripheral wall 3c of the upper die 3 opposed to this surface at a predetermined distance from the lower die 2, and the lower annular packing 5 are formed. And an annular seal gap 4A surrounded by the upper annular packing 6. The cross section of the annular seal gap 4A is a vertically long rectangle having a vertical width Y considerably larger than the horizontal width X. The pressure reducing seal portion 4 having such an annular seal gap 4A has a width dimension D2 (see FIG. 2) of about 1
It was able to fit in 0cm. An annular gap formed between the chamfered inclined surface 2d of the lower mold 2 and the inner surface of the upper mold 3 becomes a suction port 7, and the suction port 7 is formed through a ventilation path (pinch off) 8 through a molding cavity. It communicates with S. In addition, as shown in FIG. 1, the length L of the annular packing 5 projecting from the outer peripheral surface 2c of the lower mold 2 is longer than the horizontal width X by a predetermined length.

The upper die 3 is provided with a resin material inlet 9 at the bottom of the recess 3a. A suction port 10 communicating with the suction port 7 is provided on the top surface 3b, and a suction port 11 communicating with the seal gap 4A is provided on the hanging peripheral wall 3c. Piping joints are attached to these three ports, respectively.

FIG. 3 shows a state in which the mold 1A is connected to a pressure reducing device 70 and a raw material supply unit 80. The inlet 9 of the upper mold 3 is connected to the end of a raw material pipe 81 extending from the raw material supply unit 80, and a suction port 10 communicating with the molding cavity S.
Is connected to an end of a suction negative pressure pipe 72 extending from the pressure reducing device 70. The suction negative pressure pipe 72 has a resin trap 90 interposed therebetween to capture excess resin raw material overflowing from the molding cavity S. The suction port 11 connected to the annular seal gap 4A is connected to an end of a mold clamping negative pressure pipe 71 extending from the pressure reducing device 70.

Next, the operation of the above configuration will be described. To make a FRP molded product using the mold 1A, first,
When a predetermined amount of glass fiber is spread on the inner bottom surface of the lower mold 2 and the upper mold 3 is put on the lower mold 2, first, the tip of the hanging peripheral wall 3 c of the upper mold 3 has an annular plate-like lower side. As shown in FIG. 2, the distal end of the annular packing 5 is bent downward against the original shape restoring force. Subsequently, the top surface 3b of the upper mold 3 was brought into contact with the annular packing 6 provided on the top surface 2b of the lower mold 2 with the weight of the mold, and the seal gap 4A was closed by the annular packings 5 and 6. State. In this state, the injection port 9 of the upper die 3 is connected to the raw material pipe 81 and the suction ports 10 and 11 are connected to the negative pressure pipe 71 for mold clamping and the negative pressure pipe 72 for injection as shown in FIG. Next, when the air in the seal gap 4A is sucked by operating the pressure reducing device 70, the upper mold 3 and the lower mold 2 are adsorbed to each other by a differential pressure between the reduced pressure of the seal gap 4A and the atmosphere.
Mold 1A is securely clamped.

Next, when the air in the suction port 7 is sucked by the pressure reducing device 70, the pressure in the molding cavity S connected to the suction port 7 through the air passage 8 is also reduced. In this state, the raw material supply unit 80 is operated, and when the liquid resin raw material is pressed into the molding cavity S from the injection port 9 into the molding cavity S having a large flow resistance due to the narrowness of the glass fibers, the flexibility is increased. An upper mold 3 temporarily swells upward. For this reason, the inner volume of the molding cavity S increases, and the injection can be completed quickly. Then, the injection pressure and the mold clamping pressure of the resin raw material can be low. Immediately after the injection is completed, the injection port 9 is closed, and the swollen upper mold 3 gradually returns to its original shape by the atmospheric pressure and the vacuum suction force, and the resin material is filled into the molding cavity S without bubbles. Complete with

In the case of this embodiment, it takes about 15 minutes from the start of the injection of the resin material into the mold 1A to the completion of the complete filling.
And it took about 60 minutes to cure to a state where it could be removed from the mold. That is, approximately 3/4 of the time required for one molding cycle.
Is occupied by the waiting time for curing the resin raw material. Therefore, in order to increase the operation rate of the entire casting apparatus and increase productivity, a large number of molds 1A are prepared and placed, and the resin raw material is transferred to another mold that waits by using the curing waiting time. It is necessary to perform injection and filling so that both the casting apparatus and the worker work efficiently. For that purpose, a large work floor area is required, in which a large number of molds 1A can be arranged.

Therefore, it is desired that the mold 1A be made so that the floor occupied area is as small as possible. From this viewpoint, as described above, in the mold according to the invention of the prior application, the floor occupied area of the mold 50 for forming a molded product having a tray shape and a bottom area of 1 mx 1 m is almost twice the product area. About 2m ²
It will also be. On the other hand, the mold 1A of this embodiment occupies a much smaller floor area of about 1.2 m ² for producing the same molded product, and occupies a large part of the working floor area of the molding factory. The place of the waiting mold is
An area of approximately 60% is sufficient as compared with the case of using the mold of the prior application. Therefore, in the case of a factory located in an urban area where land prices are soaring or in a suburb thereof, the use of the molding die 1A of the present invention can provide extremely large economic benefits.

In the invention of the prior application, a reinforcing material is embedded in the peripheral portion of the mold so as to prevent deformation of the molding die 50 in which the depressurizing seal portion 60 having a wide width is projected from the peripheral portion. Requires skilled mold making techniques, and requires extra materials and labor. On the other hand, the reduced pressure seal portion 4 of the molding die 1A according to the present invention has a smaller width than the reduced pressure seal portion 60 of the molding die 50 of the prior application of the present invention as described above for producing a product having the same plane area. Since the cross section has a gutter shape or a box shape, it can be used as a reinforcing frame for increasing the structural strength of the entire mold 1A. Therefore, the labor and cost for reinforce the peripheral portion of the mold can be saved.

Further, in the molding die 50 of the prior application, in order to prevent the mold mating surface from shifting and moving, it is troublesome to provide the positioning pins and the pin holes of the die at a plurality of positions of each of the upper and lower dies 50A and 50B. I was However, in the molding die 1A of this embodiment, since the respective peripheral edges of the lower die 2 and the upper die 3 are provided with concave and convex shapes which are fitted to each other in the vertical direction, it is troublesome to provide the positioning pin and the pin hole. Labor and accessories can be saved.

FIG. 4 shows a main part of a molding die 1B of another embodiment. The difference from the above embodiment lies in that the shape of the lower annular packing is changed and the shape of the lower mold 2 is also partially modified. The annular packing 5A of this embodiment has a cross section formed into a hollow sector (see the broken line in the figure). Then, when the lower end surface of the hanging peripheral wall 3c of the upper die 3 comes into contact with the annular packing 5A placed on the flange portion provided outwardly around the lower edge of the lower die 2, the annular packing 5A exerts its original restoring force. As shown in the drawing, the upper and lower dies 2 and 3 are compressed and deformed to reliably fulfill the role of packing.

In each of the above embodiments, the object of the invention can be achieved even if the structure of the detailed structure is appropriately changed. For example, of course, the shape of the molding cavity S is not limited to a tray shape, and as long as it has a shape capable of injecting a liquid resin material,
The shape may be determined arbitrarily. The shape and number of the annular packings 5 and 6 and the location thereof are not limited to those shown in the drawings, and may be attached to the upper mold 3. When the flow resistance of the resin material in the molding cavity S is small, the upper mold 3 does not necessarily need to be made of a flexible material.

[0020]

As is apparent from the above description, the casting mold for casting according to the present invention can inject resin material and clamp the mold by the vacuum suction force according to the prior application of the present applicant. When the pressure reducing seal part is provided around the mold mating surface, the direction of the flat seal gap of the pressure reducing seal part is changed from the conventional horizontal direction to the vertical direction, and the width of the pressure reducing seal part is greatly reduced. By doing so, the following effects can be obtained that greatly contribute to the reduction of the cost of the product. a) When casting a reaction-curable synthetic resin, it is necessary to leave the mold filled with the resin raw materials with the mold closed because the floor area occupied by the mold can be significantly reduced. Has a unit per work floor,
Since the number of molds waiting for curing can be greatly increased, a small factory can be used accordingly, and the capital investment can be significantly reduced. b) Since the molding die is made compact and simplified, the materials and labor required for forming the die can be reduced, and the molding die can be made inexpensively and quickly. c) In addition, it is possible to efficiently handle a compact and lightweight mold. d) Since the width of the pressure-reducing seal portion can be greatly reduced, an advanced mold manufacturing technique for making this portion a reinforcing structure is not required. e) Further, since the concave and convex shape of the pressure reducing seal portion plays a role of preventing the displacement of the mold mating surface, extra labor and cost for providing the positioning pin and the pin hole as in the conventional mold can be saved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention in a state where an upper mold is separated from a lower mold.

FIG. 2 is a longitudinal sectional view of the same, with the mold closed.

FIG. 3 is a sketch drawing showing a state in which the mold is connected to a raw material supply unit and a pressure reducing device, respectively.

FIG. 4 is a longitudinal sectional view showing another embodiment of the present invention, in the vicinity of a pressure reducing seal portion.

FIG. 5 is a diagram corresponding to FIG. 3, showing a conventional example.

FIG. 6 is an enlarged vertical cross-sectional view of the vicinity of the pressure-reducing seal part.

[Description of Signs] 1A, 1B Mold D Mold S Mold Cavity 2 Lower Die 3 Upper Die 4 Decompression Seal 4A Annular Seal Gap 5, 5A, 6 Annular Packing 7 Suction Port 8 Vent 9 Inlet 10, 11 Suction Port 50 Molding Mold 50A Upper mold 50B Lower mold 51 Mold cavity 52 Vacuum suction groove 53 Injection port 60 Pressure reducing seal part 61 Annular seal gap 62 Reinforcement material 70 Pressure reducing device 71 Mold clamping negative pressure pipe 72 Injection negative pressure pipe 80 Raw material supply part 81 Raw material Piping 90 Resin trap

──────────────────────────────────────────────────の Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 39/02-39/10 B29C 39/22-39/42 B29C 33/10 B29C 33/20-33 / twenty four

Claims (2)

(57) [Claims] 1. A mold cavity is filled with a liquid resin material using a vacuum suction force, and a mold is clamped. A depressurizing seal for mold clamping is provided around a mold mating surface. The pressure reducing seal portion 4 is formed between an outer peripheral surface 2c of the lower mold 2 and a hanging peripheral wall 3c provided by extending a peripheral edge of the upper mold 3 downward, and has a vertical width. An annular seal gap 4A having a width Y larger than the lateral width X; and annular packings 5 and 6 provided around the lower mold 2 or the upper mold 3 to hermetically seal the annular seal gap 4A. A suction port 7 communicating with the molding cavity S is provided around a mold-matching surface between the portion and the annular seal portion 4A, and the annular seal gap 4A and the suction port 7 are connected to a decompression device 50, respectively. Suction ports 10 and 11 and the molding cavity Mold for casting, characterized in that a an inlet 9 of the resin material into the S. 2. The casting mold according to claim 1, wherein said lower mold 2 is made of a rigid material, and said upper mold 3 is made of a flexible material.