JP3777072B2 - Molding equipment for resin molded products - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molding apparatus for a resin molded product made of a thermoplastic resin such as polystyrene or polypropylene.
[0002]
[Prior art]
As a molding apparatus for such a resin molded product, for example, in JP-A-9-48065, a mold (female mold) in which a cavity is formed and a hot plate (male mold) facing the cavity are provided. The resin sheet sandwiched between the mold and the hot plate is heated and softened by the hot plate, and then the inside of the cavity is vacuum-sucked from a plurality of small holes formed in the inner surface of the cavity to form a resin sheet and the inner surface of the cavity. By evacuating the air between them and blowing compressed air from the hot plate side, a pressure difference is generated so that the hot plate side of the cavity has a higher pressure than the mold side with this resin sheet sandwiched between the resin sheet and the cavity It is described that it is brought into close contact with the inner surface and molded into a predetermined molded product shape.
[0003]
[Problems to be solved by the invention]
However, in such a molding method and molding apparatus, when the resin sheet is brought into close contact with the cavity inner surface, the air in the cavity between the resin sheet and the cavity inner surface is exhausted from the small hole at the bottom of the cavity as described above. Even if the inside of the cavity is vacuumed, the amount of exhaust per hour must be limited. Therefore, one molding cycle from the first molding to the next molding is naturally lengthened, and the processing efficiency is degraded. There was a problem that it contributed. On the other hand, in order to improve the exhaustability of the air in the cavity, for example, if the small hole is enlarged, the softened resin is drawn into the small hole when the resin comes into close contact with the inner surface of the cavity. As a result, the mark is largely left in the shape of a protrusion on the bottom of the product, resulting in a loss of product quality.
[0004]
The present invention has been made under such a background, and without damaging the quality of the molded product, the air exhaustability in the cavity is improved, the molding cycle is shortened, and high processing efficiency is achieved. An object of the present invention is to provide an apparatus for molding a resin molded product that can be obtained.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve such an object, the molding apparatus of the present invention includes a female mold in which a bottomed cavity is formed, and a relative separation from the female mold facing the cavity. And a pressure generating means for creating a pressure difference between the female mold side and the male mold side of the cavity with a resin sheet sandwiched between the female mold and the male mold interposed therebetween. A mounting hole is formed in the bottom of the cavity so as to open in a circular shape, and a disk-shaped bottom plate member is loosely inserted into the mounting hole, and the inner periphery of the mounting hole and the outer periphery of the bottom plate member The exhaust groove for exhausting air between the resin sheet and the inner surface of the cavity is formed so as to circulate in a circular shape, and the mounting hole extends from the opening on the cavity side to the bottom of the hole. And the outer peripheral surface of the bottom plate member is By the tapered surface shape whose diameter decreases toward the rear surface side of the bottom plate member, the exhaust groove, the groove width, characterized by being formed so as to gradually increase toward the groove bottom side.
[0006]
Therefore, according to such a molding apparatus , for example, even if the groove width of the exhaust groove is made equal to the diameter of the conventional small hole so as not to leave a large mark on the bottom of the molded product, the exhaust groove Is formed so as to circulate around the bottom of the cavity, and exhaust is performed over the entire circumference, so that a larger opening area is ensured in the exhaust path from the cavity than in the case where this conventional small hole is formed. Therefore, the air in the cavity can be quickly discharged. Further, particularly in the above molding apparatus, if the exhaust groove is formed so that the groove width is larger on the groove bottom side than the opening of the cavity bottom part, the air in the cavity is exhausted through the exhaust groove. Property can be further improved.
[0007]
In the molding apparatus of the present invention, when the pressure difference is generated between the female mold side and the male mold side of the cavity with the resin sheet sandwiched between the female mold and the male mold interposed therebetween, Similarly to the one described in Japanese Patent Laid-Open No. 9-48065, compressed air is supplied to the male mold side, and vacuum suction is performed on the female mold side through the exhaust groove to exhaust the air in the cavity. Further, the air in the cavity on the female mold side is pushed out by inflating the resin sheet with the compressed air supplied to the male mold side and closely contacting the inner surface of the cavity without performing vacuum suction on the female mold side. In this manner, exhaust may be performed. Further, when the resin sheet is sandwiched between the female mold and the male mold, the male mold is fixed and the female mold is moved, or conversely, the female mold is fixed and the male mold is moved, or these By moving both the male mold and the female mold, the male mold can be relatively separated from the female mold so as to face the cavity.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
1 and 2 show an embodiment of the molding apparatus of the present invention. FIG. 1 shows a female mold 1, FIG. 2 shows a male mold 2, and FIGS. 3 and 4 show the molding apparatus. One Embodiment of the shaping | molding method of this invention using this is demonstrated. In addition, the resin molded product A molded by this embodiment includes a disc-shaped bottom portion B and a conical surface-shaped body peripheral portion C that gradually decreases in diameter toward the bottom portion B side as shown in FIG. A cylindrical portion D is formed on the opening side of the body circumferential portion C so as to be enlarged by one step, and an opening edge of the cylindrical portion D is formed on the opening edge of the cylindrical portion D. An annular plate-like flange portion E is formed so as to spread on the outer peripheral side.
[0009]
The female mold 1 is attached to a table (not shown) so as to be able to advance and retreat toward the male mold 2 side (lower side in FIG. 1). The end surface 1A of the female mold 1 facing the male mold 2 side has A cavity 3 is formed so as to be recessed from the end face 1A. The cavity 3 is formed in accordance with the outer shape of the resin molded product A. The inner surface of the cavity 3 has a circular bottom surface 3A, and the conical surface whose inner diameter gradually decreases toward the bottom surface 3A. An inner peripheral surface 3B having a cylindrical shape and a cylindrical surface 3C that is formed so as to increase in diameter by one step on the opening side of the inner peripheral surface 3B and reach the end surface 1A. In the molding apparatus of the present embodiment, a plurality of such cavities 3 are formed in one female mold 1 so as to open side by side in the end face 1A.
[0010]
Here, in the female die 1, a mounting hole 4 is formed in the bottom surface 3A of the cavity 3 so as to open in a circular shape having a slightly smaller diameter than the bottom surface 3A. 4, a disk-shaped bottom plate member 5 is loosely inserted so as to be supported by the female mold 1 by mounting bolts 6 so as to close the mounting holes 4, and the circular surface of the bottom plate member 5 is formed in the cavity 3. The bottom surface 3 </ b> A is defined by being arranged facing the surface. A hollow exhaust chamber 7 is formed in the female mold 1 on the back surface side of the bottom plate member 5 so as to extend in the diameter direction of the mounting hole 4. Has been released. In the present embodiment, the outer diameter of the bottom plate member 5 is set to be slightly smaller than the inner diameter of the mounting hole 4, and the bottom plate member 5 is supported coaxially by the mounting hole 4. At the outer peripheral edge, a concave groove is formed between the inner periphery of the mounting hole 4 and the outer periphery of the bottom plate member 5, and the concave groove communicates with the exhaust chamber 7 to communicate with the exhaust groove 8. Has been.
[0011]
In the present embodiment, the mounting hole 4 is formed in a multi-stage shape that extends from the opening on the cavity 3 side toward the bottom of the hole with a constant inner diameter and then expands the inner diameter by one step on the exhaust chamber 7 side. In addition, the bottom plate member 5 also has an outer diameter that extends at a constant diameter from the front surface side serving as the bottom surface 3 </ b> A of the cavity 3 toward the rear surface side, and is further increased in a portion where the inner diameter of the mounting hole 4 is increased. The exhaust groove 8 is formed in a multi-stage shape that expands in diameter, and the groove width W of the exhaust groove 8 is such that the mounting hole 4 and the bottom plate member 5 are expanded by one step from the opening on the bottom surface 3A side. The width is constant until it reaches the step. In the female mold 1, a flow path 9 through which a cooling medium for cooling the molded resin molded product A is circulated is formed so as to surround each cavity 3.
[0012]
On the other hand, the male mold 2 shown in FIG. 2 is also attached to a table (not shown) so as to be able to advance and retract toward the female mold 1 side (upper side in FIG. 2) facing the cavity 3 of the female mold 1. Here, the male mold 2 can be closely attached to a male main body 11 attached to the table via the support member 10 and an end surface 11A of the male main body 11 facing the female mold 1, and an air cylinder 12 and The clamper 14 includes a flat clamper 14 that can be projected and retracted toward the female mold 1 by a guide 13. The clamper 14 has a circular shape at a position corresponding to the opening of each cavity 3 of the female mold 1. Each of the opening holes 15 is provided therethrough, and a plug 16 protruding from the center of the opening hole 15 toward the female mold 1 is attached to the end surface 11A of the male main body 11.
[0013]
Even when the clamper 14 is projected to the female mold 1 side by the air cylinder 12, the end surface 14A facing the female mold 1 side is disposed at a position retracted from the tip of the plug 16. Has been made. The male main body 11 is formed with a compressed air supply passage 17 connected to a pressure generating means such as a compressed air source (not shown) via a solenoid valve. The supply passage 17 is connected to the clamper 14. Is opened in the end face 11A so as to be located inside the opening hole 15 in a state where the is attached to the male main body 11.
[0014]
Further, a clamp portion 18 that clamps the inner peripheral surface of the cylindrical portion C of the resin molded product A and the end surface of the flange portion E facing the male mold 2 is provided at the periphery of the opening hole 15 of the clamper 14. ing. That is, in the present embodiment, an attachment groove 19 having an L-shaped cross section is formed in the opening on the female mold 1 side of the opening hole 15, and a clamp ring 20 is attached to the attachment groove 19. The ring 20 is formed with a cylindrical wall-shaped inner peripheral clamp portion 18A projecting toward the female die 1 on the inner peripheral side thereof, and is opposed to the female die 1 on the outer peripheral side of the inner peripheral clamp portion 18A. An end face clamp portion 18B having an annular plane shape is formed, and the clamp portion 18 is defined by the inner peripheral clamp portion 18A and the end face clamp portion 18B.
[0015]
Here, the inner diameter of the inner peripheral clamp portion 18A, that is, the inner diameter of the clamp ring 20, is made equal to the inner diameter of the portion of the opening hole 15 on the male body 11 side, and the outer diameter of the inner peripheral clamp portion 18A is The resin molded product A to be molded is made smaller than the inner diameter of the cylindrical surface 3C of the cavity 3 by the thickness on the opening side of the cylindrical portion C, and further, a cross section is provided on the outer periphery of the protruding end portion of the inner peripheral clamp portion 18A. A convex arc-shaped chamfer is made. On the other hand, the planar end surface clamp portion 18B is slightly protruded from the end surface 14A facing the female mold 1 side of the clamper 14, and further, the inner peripheral clamp portion 18A on the inner peripheral side of the end surface clamp portion 18B. The corners intersecting with the outer peripheral surface of each are formed in a concave arc shape in cross section.
[0016]
Next, an embodiment of the molding method of the present invention in the case where the resin molded product A as described above is molded by the molding apparatus of the embodiment configured as described above will be described. First, in this embodiment, the resin sheet S made of a thermoplastic resin such as polystyrene or polypropylene is softened by heating to a predetermined moldable temperature based on its material, thickness, outside air temperature, etc., and the female mold 1 and the male mold Between the two. Next, with the air cylinder 12 projecting the clamper 14 of the male mold 2 toward the female mold 1 side, the female mold 1 and the male mold 2 are advanced by the respective tables to approach each other. 3, the resin sheet S is sandwiched between the end surface 1A of the female mold 1 and the end surface 14A of the clamper 14 of the male mold 2 as shown in FIG.
[0017]
Here, in this embodiment, a clamp portion 18 is provided at the periphery of the opening hole 15 of the clamper 14, and the clamp portion 18 is sandwiched between the female mold 1 and the male mold 2 clamper 14. 18 clamps the resin sheet S between the periphery of the opening of the cavity 3. That is, the inner peripheral clamp portion 18A of the clamp portion 18 faces the cylindrical surface 3C of the cavity 3 and clamps the portion that becomes the cylindrical portion C of the resin molded product A therebetween, and the end surface clamp portion 18B Opposite to the end face 1A of the female mold 1, the portion to be the flange E is clamped between them. At this time, the softened resin sheet S is deformed and swollen by being pushed out by the plug 16 protruding from the end face 14A of the clamper 14, and a part of the softened resin sheet S is pushed into the cavity 3 of the female mold 1. Is done.
[0018]
Then, next, while the male main body 11 of the male mold 2 is moved forward by the table, the clamper 14 is moved backward with respect to the male mold main body 11 by the air cylinder 12. While maintaining the state in which the resin sheet S is sandwiched therebetween, the plug 16 is further protruded into the cavity 3 and the resin sheet S is pushed in. When the end surface 11A of the male main body 11 is brought into close contact with the clamper 14 and the plug 16 is protruded into the cavity 3, the male main body 11 is interposed between the resin sheet S swelled in the cavity 3 and the male mold 2. As shown in FIG. 4, the compressed air is supplied from the pressure generating means through the supply passage 17 so that the male mold 2 side in the cavity 3 is at a higher pressure than the female mold 1 side with the resin sheet S therebetween. The resin sheet S is brought into close contact with the bottom surface 3A and the inner peripheral surface 3B of the inner surface of the cavity 3, and is molded into the resin molded product A having the above shape.
[0019]
At this time, the air between the inner surface of the cavity 3 and the resin sheet S is exhausted from the exhaust groove 8 and exhausted through the exhaust chamber 7. Therefore, in the molding apparatus of this embodiment, the exhaust groove 8 is formed so as to circulate around the bottom surface 3A of the cavity 3 so that the air extends from the exhaust groove 8 to the entire periphery thereof. Exhausted. Further, the resin molded product A thus molded is cooled and cured by a cooling medium that is circulated through the flow path 9 of the female mold 1, and then the tables are moved backward to retreat the female mold 1 and the male mold 1. By separating the mold 2 from each other, the mold 2 is extracted from the cavity 3 and discharged while being integrated with the resin sheet S portion left in the form of a plate, trimmed on the outer periphery of the flange E, and provided as a product.
[0020]
Thus, according to the molding apparatus having the above configuration and the molding method using the molding apparatus, when the resin sheet S is brought into close contact with the inner surface of the cavity 3 and molded into the resin molded product A, Since the air between the inner surface of the cavity 3 is exhausted over the entire circumference from the exhaust groove 8 formed so as to circulate around the bottom surface 3A of the cavity 3, the groove width W is increased so much. A large opening area to the cavity 3 can be ensured without widening, and the air can be quickly discharged from the cavity 3 to the exhaust chamber 7 with improved exhaust performance. Therefore, the molding speed of the resin molded product A is not limited by the exhaust speed, and the molding cycle can be shortened to promote more efficient molding processing. It is possible to provide a high-quality resin molded product A by preventing the trace of the exhaust groove 8 from being left.
[0021]
Moreover, in the present embodiment, the exhaust groove 8 is formed in the outer peripheral edge portion of the bottom surface 3A of the cavity 3, and the exhaust groove 8 is larger than the case where the same groove width W is formed on the inner peripheral side. An opening area can be ensured. Further, the outer peripheral edge portion of the bottom surface 3A of the cavity 3 is compressed air from the male mold 2 when the molded resin product A to be molded is a bottomed cylindrical cup shape as in this embodiment, for example. When the resin sheet S is supplied, the resin sheet S finally comes into close contact with the inner surface of the cavity 3. By forming the exhaust groove 8 in such a portion, air remains between the resin sheet S and the inner surface of the cavity 3. It is possible to prevent this from happening and ensure reliable exhaust, and to stabilize the shape of the resin molded product A. However, depending on the shape of the resin molded product to be molded, if the exhaust groove 8 is formed at a position corresponding to the shape of the molded product, for example, the exhaust groove 8 is formed on the inner peripheral side of the outer peripheral edge portion of the bottom surface 3A of the cavity 3. Good.
[0022]
Further, in the present embodiment, the exhaust groove 8 is formed to extend with an equal groove width W from the opening side to the cavity 3 to the groove bottom side. For example, as shown in FIG. The outer peripheral surface 5A of the bottom plate member 5 is tapered so that the diameter thereof decreases toward the back surface side of the bottom plate member 5, and the exhaust groove 8 is formed so that the groove width W gradually increases toward the groove bottom side, or FIG. As shown, an annular recess is formed on the outer peripheral surface 5A of the bottom plate member 5 so as to be recessed toward the inner periphery, so that the groove width W is larger on the groove bottom side than on the cavity 3 side opening. Then, without increasing the groove width W on the bottom surface 3A of the cavity 3, the exhaust resistance can be reduced and the air in the cavity 3 can be discharged more quickly. Moreover, even when the groove width W of the exhaust groove 8 is increased on the groove bottom side in this way, in this embodiment, the inner periphery of the mounting hole 4 formed in the female die 1 and the bottom plate member attached to the mounting hole 4 Since the exhaust groove 8 is defined by the outer periphery of 5, the outer surface 5 A of the bottom plate member 5 may be processed as described above, and the advantage that the exhaust groove 8 can be easily formed is also obtained. It is done.
[0023]
On the other hand, in this embodiment, the clamp part 18 is formed in the clamper 14 of the male mold 2 in accordance with the position of the opening of the cavity 3 of the female mold 1, and the part that becomes the peripheral edge of the opening of the resin molded product A After the resin sheet S is clamped by the clamp portion 18, compressed air is supplied so that the resin sheet S is brought into close contact with the inner surface of the cavity 3. For this reason, the periphery of the opening of the resin molded product A is not deformed even when compressed air is supplied, and the size and shape of the resin molded product A can be accurately molded into a predetermined size and shape. For example, even when the resin molded product A is used as a container and a lid is attached to the opening after molding, the attaching operation of the lid can be performed reliably and easily. In addition, the portion to which the compressed air is supplied by the clamp portion 18 is airtightly independent from each other for each of the cavities 3, so that even when the plurality of cavities 3 are formed in the female mold 1, the male mold 2. As a whole, the volume of the portion to which compressed air is to be supplied can be kept small, thereby further shortening the molding cycle and reducing the amount of compressed air supplied to promote energy saving or driving the molding device. It is also possible to reduce the force.
[0024]
Further, the clamp portion 18 includes an inner peripheral clamp portion 18A facing the cylindrical surface 3C of the opening of the cavity 3 and an end surface clamp portion 18B facing the end surface 1A of the female mold 1 at the periphery of the cylindrical surface 3C. By clamping the resin sheet S between the inner peripheral clamp part 18A and the cylindrical surface 3C, the inner diameter of the cylindrical part C of the opening of the resin molded product A is formed with high accuracy. By clamping the resin sheet S between the end surface clamp portion 18B and the end surface 1A of the female mold 1, the thickness of the flange portion E of the resin molded product A is formed with high accuracy and the end surface is also flat. Since it is formed, that is, the flange portion E can be accurately formed with a predetermined dimensional shape. However, when the cup-shaped resin molded product A is used as a container as described above, in order to attach a lid to the opening, for example, a film-like lid is welded to the end surface of the flange E by ultrasonic waves. A method of attaching is generally known, but according to the present embodiment, the flange portion E is formed with high accuracy, and even when the lid is attached by such ultrasonic welding, It is possible to perform attachment with appropriate strength.
[0025]
In the present embodiment, the exhaust chamber 7 is opened to the outside of the female mold 1, and the air between the resin sheet S pushed into the cavity 3 and the inner surface of the cavity 3 is compressed by the resin sheet S. When closely contacting the inner surface of the cavity 3 by air, it is exhausted from the exhaust groove 8 by being pushed out by the expanding resin sheet S, and is exhausted through the exhaust chamber 7. When the resin sheet S is brought into close contact with the inner surface of the cavity 3 by connecting the vacuum suction means as a part of the pressure generating means, a negative pressure is generated between the resin sheet S and the inner surface of the cavity 3, A larger pressure difference may be applied to the male mold 2 side of S, whereby the air can be exhausted more quickly and the molding cycle can be further shortened. 1 to 4, the female mold 1 is disposed on the upper side with the cavity 3 opened downward, and the male mold 2 is disposed on the lower side with the plug 16 projecting upward. Although they can be separated from each other, the arrangement of the female mold 1 and the male mold 2 can be appropriately set according to molding conditions and the like.
[0026]
【The invention's effect】
As described above, according to the present invention, the exhaust groove is formed to circulate at the bottom of the cavity, and the air between the cavity inner surface and the resin sheet is discharged from the exhaust groove over the entire circumference. As a result, the air in the cavity can be quickly exhausted without leaving a mark that impairs the quality of the molded product, which enables shortening of the molding cycle and high processing efficiency. Become.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a female mold 1 in an embodiment of a molding apparatus of the present invention.
FIG. 2 is a side sectional view showing a male mold 2 in an embodiment of a molding apparatus of the present invention.
3 is a view showing a state where a resin sheet S is sandwiched between a clamper 14 of a female mold 1 and a male mold 2 in an embodiment of the molding method of the present invention. FIG.
4 is a view showing a state in which a resin sheet S is in close contact with the inner surface of a cavity 3 in an embodiment of the molding method of the present invention. FIG.
5 is a cross-sectional view showing a modification of the exhaust groove 8. FIG.
6 is a cross-sectional view showing a modification of the exhaust groove 8. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Female type | mold 1A End surface 2 of Female type | mold 1 Male type 3 Cavity 4 Mounting hole 5 Bottom plate member 7 Exhaust chamber 8 Exhaust groove 11 Male type | mold main body 14 Clamper 15 Opening hole 16 Plug 17 Compressed air supply path 18 Clamp part 18A Inner circumference clamp Part 18B end face clamp part A resin molded product W groove width of exhaust groove 8

Claims (1)

A female mold in which a bottomed cavity is formed, a male mold that is opposed to the female mold so as to be opposed to the female mold, and a resin sheet that is sandwiched between the female mold and the male mold And a pressure generating means for generating a pressure difference between the female mold side and the male mold side of the cavity, and a mounting hole is formed at the bottom of the cavity so as to open in a circular shape. The disc-shaped bottom plate member is loosely inserted into the mounting hole, and the air between the resin sheet and the inner surface of the cavity is exhausted between the inner periphery of the mounting hole and the outer periphery of the bottom plate member. exhaust groove that is being formed so as to surround circumferentially, with the mounting hole extends in constant inner diameter toward the hole bottom from the opening of the cavity side, the outer peripheral surface of the bottom plate member bottom plate The taper surface is reduced in diameter toward the back side of the member. The Rukoto, the exhaust groove, the groove width of the molding apparatus of a resin molded article, characterized by being formed so as gradually increases toward the groove bottom side.

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