JP3568670B2 - Method for producing plastic skin and powder slush molding apparatus - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a plastic skin and a powder slush molding apparatus used for the method.
[0002]
[Prior art]
BACKGROUND ART Plastic skin is widely used as a surface component of plastic products such as instrument panels of automobiles.
The plastic skin previously formed into a predetermined shape is often used in the production of plastic products.
Conventionally, as a method for producing the plastic skin, there is a plastic powder molding method. This plastic powder molding method includes a powder slush molding device 60 including a bucket 61 having an open plastic powder accommodating portion 62 and a slash molding die 71 that is closed and combined with the bucket 61 as shown in FIG. The plastic powder 80 in the bucket is dropped and adhered to the heated mold surface 72 of the slash molding die 71 to form a molten plastic layer, and the molten plastic layer is cooled and hardened. This is a method of forming a plastic skin. The plastic skin formed on the mold surface 72 is then peeled off from the mold surface 72.
[0003]
However, according to the powder slush molding method, the mold surface 73 substantially perpendicular to the rotating shaft 81 is substantially parallel to the falling direction of the plastic powder, so that the contact time with the plastic powder is short, and the plastic powder is Since there is almost no accumulation, the amount of plastic powder attached tends to be smaller than that of the mold surface 74 of other general parts. As a result, the thickness of the portion of the plastic skin obtained on the mold surface 73 that is substantially perpendicular to the rotation axis is usually about 30% smaller than the thickness of the other general mold surface 74. I was
[0004]
When a plastic product is molded using a plastic skin having a thin portion as described above, the foam on the back surface of the plastic skin may penetrate through the thin portion and the product appearance may be impaired.
However, according to the conventional powder slush molding method, the amount of plastic powder adhering to the mold surface cannot be increased only at a desired portion of the mold surface. Therefore, the thickness of the entire plastic skin is increased so that the thin portion is formed to have a predetermined thickness or more.
However, in that case, the plastic skin becomes thicker than necessary due to the part molded on the general mold surface, and the flexibility of the plastic skin is impaired or heavier. There were problems such as being up.
[0005]
[Problems to be solved by the invention]
Therefore, the present invention has been made in view of the above points, and a method of manufacturing a plastic skin capable of increasing the amount of plastic powder adhering to a mold surface of a powder slush molding die only in a desired portion of the mold surface and using the same. And a powder slush molding apparatus.
[0006]
[Means for Solving the Problems]
The invention relating to a method for producing a plastic skin comprises rotating a powder slush molding device including a bucket having an open plastic powder storage portion and a slash molding die combined with the bucket by closing the opening so that the bucket is inverted. In a method for producing a plastic skin, the molten plastic layer is formed by dropping and adhering a plastic powder in a bucket on the mold surface of the heated slush molding die, and cooling and curing the molten plastic layer. A main pipe having a powder outlet toward the mold surface of the slush molding die and connected to a gas blowing device outside the bucket; and Consists of multiple powder suction tubes that reduce pressure The angle b between the powder suction pipe and the main pipe is an obtuse angle, and the angle a of the part where the main pipe is divided into a plurality of parts from the middle of the main pipe and the leading ends each become the powder outlet and the divided part is The powder spraying pipe is formed into an acute angle, and the powder suction pipe is branched from the main pipe between the divided portion and the powder outlet. Before or during the rotation of the powder slush molding device, the gas is blown into the main pipe from the gas blowing device before the rotation of the powder slush molding device, thereby reducing the pressure from the tips of the plurality of powder suction tubes. The plastic powder in the bucket is sucked into the powder spraying pipe, and the plurality of powders are blown out. Characterized in that the blown simultaneously from the mouth to the plurality of mold surfaces required portion of the slush molding die.
[0007]
In the manufacturing method of the present invention, the gas blown into the main pipe of the powder blowing pipe is blown from the powder outlet at the tip through the main pipe. At this time, the gas in the powder suction pipe that branches off from the middle of the main pipe is drawn into the main pipe by the gas flowing through the main pipe, so that the pressure in the powder suction pipe is reduced, and the plastic powder in the bucket is sucked from the tip of the powder suction pipe. The plastic powder sucked into the powder suction pipe reaches the main pipe from the powder suction pipe, and blows out from a powder outlet at the tip of the main pipe together with gas flowing through the main pipe.
[0008]
Therefore, according to the manufacturing method of the present invention, in addition to the adhesion of the plastic powder to the mold surface due to the fall of the bucket due to the inversion of the bucket, the plastic powder blown out from the powder outlet of the powder spray tube adheres to the heated mold surface. Will do. Therefore, if the powder outlet is directed to the desired portion of the mold surface, the amount of the plastic powder to be attached can be intensively increased only in the desired portion of the mold surface.
[0009]
The suction of the plastic powder by the powder suction tube and the spraying from the powder outlet are based on a principle widely used in the past. That is, the principle is that, around the moving fluid, the surrounding fluid is drawn into the moving fluid to reduce the pressure. This principle is used in vacuum pumps and the like in the field of chemical experiments.
[0010]
On the other hand, the invention of the powder slush molding device comprises a bucket having an open plastic powder receiving portion, and a slush molding die that is closed to the opening and combined with the bucket. In a powder slush molding apparatus that adheres to a mold surface of the slush molding mold in a heated state, a main pipe having a powder outlet toward the mold surface of the slush molding mold and connected to a gas blowing device outside the bucket, A plurality of powder suction pipes provided in the main pipe so as to branch off from the middle thereof, the inside of which is decompressed by gas flowing through the main pipe; and an angle b between the powder suction pipe and the main pipe is obtuse. In addition, the main pipe is divided into a plurality of parts from the middle thereof, An angle a of the divided part becomes an acute angle while becoming a discharge port, and the powder suction pipe is configured such that the powder suction pipe is branched from the main pipe between the divided part and the powder discharge port; Is provided so that the tip of the powder suction tube is located in the plastic powder accommodating portion of the bucket.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing an example of a powder slush molding apparatus used in the method for producing a plastic skin according to the present invention, FIG. 2 is a cross-sectional view of the powder slush molding apparatus showing a time when plastic powder is sprayed, and FIG. FIG. 4 is a cross-sectional view of the powder slush molding apparatus showing a state at the time of spraying a plastic powder, and FIG. 5 is a side view showing an example of a powder spray pipe.
[0012]
6 to 9 are partial cross-sectional views showing the operation of the powder blowing pipe, in which FIG. 6 is a view showing a gas blowing start state, FIG. 7 is a view showing a state in which the powder suction pipe is depressurized, FIG. 8 is a diagram showing a state where the plastic powder is sucked into the powder suction tube, and FIG. 9 is a diagram showing a state where the plastic powder is sucked into the main tube.
[0013]
A powder slush molding apparatus 10 according to one embodiment of the present invention shown in FIG. 1 includes a bucket 21, a slash molding die 31, and a powder spray tube 41 attached to the bucket. A rotation with an inverted is added.
[0014]
The bucket 21 is for accommodating a plastic powder 50 for powder slush molding, and has a container-like shape having a plastic powder accommodating portion 22 having an open upper portion. A vent 24 is formed in the upper part of the side wall 23 of the bucket, and a filter material 25 is fitted into the vent 24. The vent hole 24 allows gas to escape from the powder slush molding device 10 to the outside when spraying plastic powder, which will be described later. On the other hand, the filter material 25 is for preventing the plastic powder 50 from escaping from the powder slush molding apparatus 10 to the outside through the vent hole 24. As the filter material 25, a mesh body or a foam mainly composed of continuous ventilation holes is used. The upper end of the bucket 21 is a flange 26 protruding outward, and is used as a mating surface with the slash forming die 41.
[0015]
The slash molding die 31 is for molding a plastic skin of a desired shape, has a mold surface 32 on the inside, and has a flange 33 on the outer periphery to be fitted with the flange 26 of the bucket 21. The mold surface 32 is for molding a plastic skin into a desired shape, and has an uneven shape corresponding to the shape of a molded product. Further, the slash forming die 31 has a heat medium pipe 34 disposed on the outer surface thereof. A heat medium such as a heating oil is passed through the heat medium tube 34 so that the heat can heat the mold surface 32 to a predetermined temperature. Of course, other heating means using a heater or hot air may be used instead of the heating medium tube 34.
[0016]
The powder spraying tube 41 is for spraying a plastic powder on a desired portion of the mold surface of the slash forming mold 31 and is attached to the bucket 21. The attachment is appropriately performed by making a hole in a part of the bucket 21 and passing it through, or using a bar member 47 bridged between the bucket 21 and the like.
[0017]
As shown in FIG. 5, the powder blowing pipe 41 includes a main pipe 42 and a powder suction pipe 45 branched from the main pipe 42.
The main pipe 42 has a powder outlet 43 at one end, and the other end is connected to a gas blowing device P such as a compression pump outside the bucket 21. The main pipe 42 of this embodiment is divided into a plurality of parts in the middle, and the respective ends constitute powder outlets 43. Further, the powder outlet 43 is formed toward a desired mold surface portion of the slash molding die 31, in this example, a mold surface 35 which is substantially perpendicular to the rotation axis of the powder slush molding device 10. Then, a gas such as compressed air is sent from the gas blowing device P into the main pipe 42 and blows out from the powder blowing port 43. In the main pipe 42, the angle a of the divided portion 42a is acute so that the gas blown from the gas blowing device P flows smoothly to the powder blowing port 43.
[0018]
On the other hand, the powder suction pipe 45 is for sucking the plastic powder 50 in the bucket 21 into the main pipe 42, and is provided between the powder outlet 43 and the portion 42 a where the main pipe 42 is divided in the middle. The tip 46 is disposed in the plastic powder accommodating portion 22 of the bucket 21. The powder suction pipe 45 is formed at an obtuse angle b between the powder suction pipe 45 and the main pipe 42 in order to make it difficult for the gas flowing through the main pipe 42 to enter the powder suction pipe 45. Further, it is preferable that the diameter of the powder suction pipe 45 be smaller than the diameter of the main pipe 42 so that the gas in the main pipe 42 is prevented from entering.
[0019]
Next, an example of a method for producing a plastic skin using the powder slush molding apparatus 10 will be described.
The powder slush molding device 10 is attached to a rotating device (not shown). A well-known powder slush molding plastic powder 50 made of vinyl chloride resin powder or the like is stored in the plastic powder storage portion 22 of the bucket 21, and the upper opening of the plastic powder storage portion 22 is closed. The bucket 21 and the slash forming mold 31 are combined. At this time, the tip of the powder suction tube 45 of the powder spraying tube 41 is located in the plastic powder 50 of the plastic powder storage portion 22 of the bucket 21.
[0020]
The mold surface of the slush mold 31 is heated to a predetermined temperature by a heat medium flowing through the heat medium pipe 34. The heating temperature varies depending on the type of the plastic powder 50 to be used, but the temperature condition in a general powder slush molding method is applied.
[0021]
In this state, a gas such as air is blown into the main pipe 42 of the gas blowing pipe 41 by the gas blowing apparatus P before the rotation of the powder slush forming apparatus 10. As shown in FIG. 6, the gas blown into the main pipe 42 flows through the main pipe 42 and blows out from a powder outlet 43 at the tip of the main pipe 42. As a result, as shown in FIG. 7, the gas in the powder suction pipe 45 is drawn toward the main pipe 42 and the pressure in the powder suction pipe 45 is reduced, so that the plastic powder 50 in the plastic powder accommodating portion 22 becomes powdery. The powder is sucked into the powder suction tube 45 from the tip of the suction tube 45 as shown in FIG. The plastic powder 50 sucked into the powder suction pipe 45 is further sucked into the main pipe 42 and merges with the gas flowing through the main pipe 42 as shown in FIG. As shown in FIG. 2, the plastic powder 50 is blown out from a powder outlet 43 at the tip of the main pipe 42, and is blown onto the mold surface 35 of the slash forming mold 31 which is substantially perpendicular to the rotating shaft 51.
The plastic powder 50 sprayed on the mold surface 35 of the slash mold 31 that is substantially perpendicular to the rotation shaft 51 adheres to the mold surface 35 by the heat of the mold surface 35.
[0022]
Next, the spraying of the plastic powder is stopped, and the powder slush molding device 10 is rotated. During the rotation, when the bucket 21 is turned upside down as shown in FIG. 3, the plastic powder 50 in the bucket 21 falls into the slash molding die 31 and accumulates on the mold surface 32. The heat adheres to the mold surface 32. At this time, the mold surface 35 substantially perpendicular to the rotation shaft 51 is substantially parallel to the falling direction of the plastic powder 50, so that the plastic powder 50 is less likely to accumulate, and the contact time with the mold surface 35 is shortened. The amount of plastic powder adhering to the mold surface 35 is reduced. However, since the plastic powder 50a sprayed by the powder blowing pipe 41 has already adhered to the mold surface 35 substantially perpendicular to the rotation shaft 51, it is possible to compensate for the insufficient adhesion of the plastic powder 50 due to the rotation. it can.
[0023]
Further, during the rotation of the slush molding device, as shown in FIG. 4, when the bucket 21 returns downward, the powder blowing pipe 41 again causes the plastic powder to be applied to the mold surface 35 substantially perpendicular to the rotation shaft 51. 50 may be sprayed. The spraying of the plastic powder 50 in this case is appropriately determined, for example, every time the slash molding die 10 rotates or every predetermined number of rotations. Note that the plastic powder is not sprayed by the powder spray tube 41 before the powder slush molding die 10 is rotated, but the plastic powder is sprayed by the powder spray tube 41 only during the rotation of the slush molding die 10. You may.
[0024]
The plastic powder adhered to the mold surface 32 of the slush molding die 31 by spraying the plastic powder and rotating the powder slush molding device is integrally melted by the heat of the mold surface 32, and the molten plastic layer 52 is formed on the mold surface 32. Form.
[0025]
After the powder slush molding apparatus 10 has been rotated for a predetermined time or a predetermined number of times, the rotation is stopped, and the excess plastic powder not used for adhesion to the mold surface 32 is removed from the plastic powder receiving portion 22 of the bucket 21. Collect within. The conditions such as the number of rotations or the rotation time are appropriately determined similarly to the ordinary powder slush molding method. At the same time, the temperature of the mold surface 32 is lowered by adjusting the temperature of the heat medium flowing through the heat medium pipe 34 or by stopping the flow of the heat medium, and the like. Is cooled and cured. Thereby, the molten plastic layer 52 is shaped into the shape of the mold surface 32, and becomes a desired plastic skin.
Thereafter, the plastic skin is removed from the mold surface 32 and trimmed as appropriate to obtain a product.
[0026]
The plastic skin obtained in this way has a sufficient thickness at the portion molded on the mold surface 35 substantially perpendicular to the rotating shaft 51, and the thickness of the portion molded on the other mold surface portion is the same as that of the conventional plastic. It was the same as the plastic skin molded by the powder slush molding method. Further, the weight of the plastic skin was almost the same as that of the conventional product manufactured according to the present invention.
[0027]
In the above-described embodiment, the plastic powder is sprayed only on the mold surface substantially perpendicular to the rotation axis of the powder slush molding apparatus. However, the manufacturing method and the molding apparatus of the present invention are not limited thereto, and the skin is not limited thereto. A plastic powder is sprayed on a mold surface for molding a portion to be increased in thickness.
[0028]
【The invention's effect】
As shown and described above, according to the manufacturing method of the present invention, in addition to applying the plastic powder to the entire mold surface by rotating the powder slush molding device, the plastic powder is sprayed on a desired portion of the mold surface. Therefore, the plastic powder can be sufficiently adhered to the desired portion of the mold surface. Therefore, in the obtained plastic powder, the thickness of the portion molded at the desired portion of the mold surface can be set to a desired thickness.
[0029]
In particular, according to the manufacturing method of the present invention, a sufficient amount of plastic can be applied to a mold surface portion to which plastic powder is unlikely to adhere due to the rotation, such as a mold surface portion substantially perpendicular to the rotation axis of the powder slush molding device. Since the powder can be adhered, the thickness of the obtained plastic skin can be prevented from being partially reduced. In addition, since there is no possibility that extra plastic powder adheres to the mold surface portion to which the plastic powder is not sprayed, the amount of plastic powder used does not excessively increase, and it is economical. Since the thickness does not increase to a point where there is no increase, the increase in weight can be minimized, and the flexibility is not impaired.
[0030]
Further, according to the powder slush molding apparatus of the present invention, the plastic skin having the above advantages can be easily manufactured, and the structure of the apparatus itself is simple, so that the increase in the cost of the apparatus is minimized. And has the advantage of being easy to maintain.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a powder slush molding apparatus used in the method for producing a plastic skin of the present invention.
FIG. 2 is a cross-sectional view of the powder slush molding apparatus showing the time of spraying plastic powder.
FIG. 3 is a cross-sectional view of the powder slush forming apparatus showing a state where a bucket is inverted.
FIG. 4 is a cross-sectional view of the powder slush molding apparatus showing the time of spraying plastic powder.
FIG. 5 is a side view showing an example of a powder spray tube.
FIG. 6 is a partial cross-sectional view of a powder spraying pipe showing an operation at the start of spraying of plastic powder.
FIG. 7 is a partial cross-sectional view of the powder blowing pipe showing a state where the pressure of the powder suction pipe is reduced.
FIG. 8 is a partial cross-sectional view of the powder blowing tube showing a state where the plastic powder is sucked into the powder suction tube.
FIG. 9 is a partial cross-sectional view of the powder blowing pipe showing a state in which the plastic powder is sucked into the main pipe.
FIG. 10 is a sectional view showing a conventional powder slush molding apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Powder slash forming apparatus 21 Bucket 22 Powder accommodating part 31 Slash forming mold 32 Mold surface 41 Powder blowing pipe 42 Main pipe 43 Powder blowing port 45 Powder suction pipe 46 Tip of powder suction pipe P Gas blowing apparatus

Claims (2)

A powder slush molding device (10) comprising a bucket (21) having an open plastic powder storage portion (22) and a slush molding die (31) closed to the opening and combined with the bucket (21) is connected to the bucket (21). The plastic powder in the bucket (21) is dropped onto the heated slash mold (31) to form a molten plastic layer, and the molten plastic layer is cooled. In a method for producing a plastic skin, which is cured to form a plastic skin,
A main pipe (42) having a powder outlet (43) directed toward the mold surface of the slash forming die (31) and connected to a gas blowing device (P) outside the bucket; and from the middle of the main pipe (42). A plurality of powder suction pipes (45) which are provided so as to be branched and whose pressure is reduced by gas flowing through the main pipe (42); and the powder suction pipe (45) and the main pipe (42) The angle b between them is obtuse, and the main pipe (42) is divided into a plurality of parts from the middle thereof, the ends of which become the powder outlets (43), and the angle a of the divided part (42a) becomes acute. And a powder blowing pipe (4) in which the powder suction pipe (45) branches off from the main pipe (42) between the dividing part (42a) and the powder outlet (43). ) And, arranged so that the plurality of powder suction tube (45) tip (46) is positioned within the plastic powder containing portion of the bucket (22),
Before or during rotation of the powder slush molding device (10), a gas is blown from the gas blowing device (P) into the main pipe (42), thereby reducing the pressure of the plurality of powder suction pipes. The plastic powder in the bucket (21) is sucked into the powder spray pipe (41) from the tip (46), and is simultaneously transferred from the plurality of powder outlets (43) to a plurality of required surfaces of the slash molding die (31). A method for producing a plastic skin, characterized by spraying. A bucket (21) having an open plastic powder receiving portion (22) and a slash forming die (31) combined with the bucket (21) by closing the opening to rotate the bucket (21) with the inverted In the powder slush molding device (10) for attaching the plastic powder to the mold surface of the slush molding die (31) in a heated state,
A main pipe (42) having a powder outlet (43) directed toward the mold surface of the slash forming die (31) and connected to a gas blowing device (P) outside the bucket; And a plurality of powder suction pipes (45), which are provided so as to branch off from the main pipe (42) and the inside of which is depressurized by gas flowing through the main pipe (42), and the powder suction pipe (45) and the main pipe (42). The main pipe (42) is divided into a plurality of parts at an intermediate point thereof, and the leading ends thereof become the powder outlets (43), respectively, and the angle a of the divided part (42a) is an acute angle. Powder spraying, wherein the powder suction pipe (45) is branched from the main pipe (42) between the divided part (42a) and the powder outlet (43). (41), powder slush molding apparatus is characterized in that provided so as to be positioned in the plastic powder housing portion (22) of the tip (46) of the bucket (21) of the plurality of powder suction pipe (45).

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