JP2011104784A - Packing machine for in-mold molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packing machine which can improve the surface properties and fusion properties of a design surface contacted with the plunger tip of the packing machine for a foamed molding when preliminarily foamed particles are in-mold-molded. <P>SOLUTION: In the packing machine for in-mold molding having the main tube 3 which packs the preliminarily foamed particles in a mold, a cylinder 2 which reciprocates the plunger 6 in the main tube 3, and a base part 1 having a branch tube 5 part which receives the preliminarily foamed particles and supplied them to the main tube 3, a space 23 is formed in the plunger 6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a filling machine for filling pre-expanded particles in a mold, and more specifically, the surface properties and the fusing property of the design surface of a foam molded product in contact with the tip of a filling machine plunger. The present invention relates to a filling machine that can significantly improve

  In various types of in-mold plastic molding such as expanded polystyrene, expanded polyethylene, expanded propylene, and the like, a filling machine is used when filling these pre-expanded particles into a mold. Conventionally, foamed polystyrene has been the main raw material used for foamed plastic in-mold molding, but now, in-mold molding using various pre-foamed particles such as foamed polyethylene and foamed polypropylene is performed in addition to foamed polystyrene. It has become.

  Among these pre-expanded particles, for example, expanded polyethylene pre-expanded particles and expanded polypropylene pre-expanded particles are soft in the base resin itself, and the pre-expanded particles themselves are compressed under the influence of compressed air for granulation used during filling. The filling density tends to increase locally. This is called overfilling. In the overfilled portion, the gap between the pre-expanded particles at the time of filling is narrowed, and the vapor necessary for foaming / fusion is difficult to pass. As a result, local fusion defects may occur in the vicinity of the tip of the filling machine plunger.

  For the poor fusion considered to be caused by the above-mentioned overfilling, a method in which steam having a temperature higher than the proper fusion temperature of the pre-expanded particles is supplied into the mold and the overfilled portion is forcibly fused. However, this method not only increases the amount of steam used and deteriorates the economic efficiency, but also excessively heats the portions other than the overfilled portion of the foam molded product. There were also secondary problems such as sink marks on some of the products and a significant deterioration in yield.

  Further, in Patent Document 1, a plurality of steam grooves are formed in the main pipe portion and the plunger tip at the tip of the filling machine, thereby providing a gap at the boundary between the pre-foamed particle and the filling machine plunger portion, and steam in the overfilling portion. An invention for spreading the above is disclosed.

  However, in recent years, filling of the pre-expanded particles tends to be difficult due to the complicated shape and thinning of the foam molded product. Usually, as an operation to increase the filling property of the complicated shape part and thin part of the foam molded product, it is frequently performed to set the air pressure for sending the granule for filling high, but depending on the shape and filling condition of the foam molded product, Again, overfilling of the foam molding product at the tip of the filling machine is caused, and it is becoming more difficult than before to secure a good fusion for the reason described above.

  In addition, there were significant structural problems with the filling machine. The casting part of the mold has steam supply ports (core vents) for fusing the pre-expanded particles arranged at a pitch of about 20 mm and has a structure capable of supplying uniform steam, but the plunger of the filling machine There was no steam supply port at the tip, and it was easy to cause poor fusion. Further, since the plunger of the filling machine has a larger heat capacity than the casting, the plunger is not easily heated during heating and has a structure that promotes the occurrence of poor fusion.

JP 2002-292668 A

  An object of the present invention is to provide a filling machine capable of improving the surface property and the fusing property of a design surface in contact with a tip of a filling machine plunger of a foam molded product when pre-expanded particles are molded in a mold.

  The present invention has been made in order to solve the above-described problems, and includes a main pipe portion filled with pre-expanded particles in a mold, a cylinder portion for reciprocating a plunger in the main pipe portion, and receiving the pre-expanded particles. In the in-mold foaming filling machine having a trunk part having a branch pipe part to be supplied to the main pipe part, a space part is provided inside the filling machine plunger.

That is, the present invention has the following configuration.
[1] A main part having a main pipe part filled with pre-expanded particles in a mold, a cylinder part for reciprocating a plunger in the main pipe part, and a branch pipe part for receiving the pre-expanded particles and supplying them to the main pipe part. An in-mold foaming filling machine having a space provided inside the plunger.
[2] A communication portion that is formed when the plunger is closed and that is surrounded by the plunger, the plunger seal, and the front pipe and that is open toward the foam molded product design surface is provided with a communication portion that communicates from the outer surface of the front pipe. [1] The filling machine according to [1].
[3] A space portion inside the plunger and a gap portion opened toward the design surface surrounded by the plunger, the plunger seal, and the front pipe are communicated with each other through the plunger communicating portion [2 ] The filling machine as described in.
[4] The communication hole formed in the plunger design surface from the space inside the plunger to the plunger design surface is formed, and the communication hole formed in the plunger design surface is smaller than the diameter of the pre-expanded particle. Filling machine.
[5] The filling machine according to [4], wherein the plunger is made of an aluminum material.
[6] The filling machine according to [5], wherein the communication hole formed in the design surface of the plunger is formed by a core vent.
[7] The filling machine according to [6], wherein the core vent is made of an aluminum material.

  According to the in-mold molding filling machine of the present invention, it is possible to improve poor fusion of the design surface in contact with the foaming machine tip of the foam molded product and deterioration of surface properties. Therefore, it is possible to improve productivity mainly by reducing defects.

  Furthermore, since it is not necessary to perform excessive heating on the entire foamed molded product for preventing poor fusion, the time required for cooling and solidifying the foamed molded product that has been excessively foamed can be greatly shortened and the molding cycle can be shortened. At the same time, a reduction in the amount of steam used and an increase in yield due to a reduction in sink marks on the foam molded product can be achieved at the same time.

It is a general view of a filling machine. It is a front-end | tip figure of a main pipe when a plunger fits in the front pipe of the conventional filling machine, and the filling port is closed. FIG. 5 is a front view of the main pipe when the plunger is accommodated in the front pipe of the first embodiment of the present invention and the filling port is closed. FIG. 5 is a front view of the main pipe when the plunger is accommodated in the front pipe of the first embodiment of the present invention and the filling port is closed. FIG. 7 is a front view of a main pipe portion and a cross-sectional view taken along line A-A ′ when a plunger is accommodated in a front pipe according to a second embodiment of the present invention and a filling port is closed. FIG. 6 is a front view of a main pipe portion and a B-B ′ sectional view when a plunger is accommodated in a front pipe of a second embodiment of the present invention and a filling port is closed. FIG. 6 is a front view of a main pipe portion when a plunger is accommodated in a front pipe and a filling port is closed according to a second embodiment of the present invention, and a C-C ′ sectional view. FIG. 7 is a front view of a main pipe portion when a plunger is accommodated in a front pipe of a third embodiment of the present invention and a filling port is closed. It is a plunger figure of 4th embodiment of this invention, and DD 'sectional drawing. It is a plunger figure of 4th embodiment of this invention, and EE 'sectional drawing. FIG. 3 is a front view of the main pipe portion when the plunger is closed showing the best mode of the present invention.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an overall view of the filling machine, showing a cross section in a state where the plunger 6 is retracted and pre-expanded particles can be filled. The filling machine is large and is composed of three parts: a main part 1, a cylinder part 2, and a main pipe part 3.

  The trunk portion 1 is composed of a straight pipe 4 and a branch pipe 5 branched from the straight pipe 4. A front cover 13 of the cylinder portion 2 is joined to a rear end portion of the straight pipe 4, and a front end portion of the straight pipe 4 is joined. The main pipe part 3 is joined. The branch pipe 5 is attached with a nipple for connecting a hose (not shown) from the raw material hopper.

  The cylinder part 2 has a front cover 13 at the front end of the cylinder pipe 17, a rear cover 9 at the rear end, and a piston 10 that is slidably mounted inside the cylinder pipe 17. A rod 14 having a plunger 6 fixed at the tip is stored. The rear cover 9 is provided with an air port 11 at the center, and when the instrument air is introduced into the air port 11, the piston 10 moves forward, the plunger 6 is accommodated in the front pipe 21, and the filling port is closed. (This state is sometimes referred to as “when the plunger is closed”). The piston 10 is provided with an O-ring 16 at a portion in contact with the cylinder pipe 17. The front cover 13 has an air port 12 opened on a side surface, and the introduction of instrument air to the air port 12 causes the piston 10 to retreat, so that the pre-expanded particles can be filled. A rod 14 is inserted through the central portion of the front cover 13, and an O-ring 7 is attached to a portion in contact with the rod 14.

  An outline of the main pipe section 3 will be described. The main pipe portion 3 varies in various ways such as the position and angle of the air nozzle 15 and the number of holes depending on the mold, raw material, and filling method, but the basic configuration is substantially the same. The main pipe portion 3 is composed of an outer pipe 19 having a slightly different diameter and an inner / outer double cylinder of the inner pipe 20, and a cylindrical gap is formed in the gap between both pipes. This gap serves as a path for filling air supplied from the air port 18. The outer pipe 19 and the inner pipe 20 are joined at the tip of the gap, and a plurality of small holes are formed in the joined portion. It becomes a structure which can eject from the air nozzle 15 through the path | route.

  Further, the distal end portion of the main pipe portion 3 will be described in detail. The distal end portion of the main pipe portion 3 is composed of a front pipe 21 having a gradient that becomes thicker toward the distal end, and has a structure in which the focal point of the air path ejected from the air nozzle 15 is formed near the front end opening portion of the front pipe 21. . This is called far-focus and is an important design element for preventing overfilling. It is preferable to adjust the far focus by using different filling methods, the magnification of the pre-expanded particles, and the resin type.

  Subsequently, the present invention will be described in detail.

  FIG. 2 is a sectional view of a conventional plunger, and FIGS. 3 and 4 are sectional views of examples of the plunger of the present invention. The present invention is characterized in that a space is provided inside the plunger. As shown in FIG. 2, since the conventional plunger 6 has a solid structure, the heat capacity is larger than that of the cast part, and the failure to secure the heating rate during heating induces poor fusion. It was thought that. Therefore, in the present invention, the space portion 23 is provided inside the plunger 6 to reduce the heat capacity and to ensure the temperature rising rate. The form of the space 23 is not particularly limited as long as it has a strength capable of maintaining the shape of the plunger. As a specific shape of the space portion 23, for example, FIG. 3 shows an example in which the plunger is cut from the side surface of the plunger 6 and a through hole is provided to form the space portion 23. There is no particular restriction on the size and shape of the through hole, and there is no particular problem as long as it has the strength to hold the shape of the plunger, but increasing the through hole diameter as much as possible and increasing the number of through holes, This is preferable because it leads to a decrease in the heat capacity of the plunger.

  FIG. 4 shows an example in which the plunger 6 is cut from the sliding direction of the plunger and the space portion 23 is provided inside the plunger 6 as another example. Also in this case, if there is no problem in the strength with which the shape of the plunger 6 can be maintained, it is preferable to reduce the thickness of the plunger 6 after cutting as much as possible. In this example, since a hole is formed in the plunger 6 so as to face the design side of the foam molded product, it is necessary to provide a stopper 27 so that the pre-foamed particles do not enter the plunger space 23. The plug 27 preferably has a high thermal conductivity in order to ensure a heating rate during heating and is lightweight from the viewpoint of reducing the heat capacity. In particular, an aluminum material, copper, or a copper alloy material is preferable from the viewpoint of cost, and the aluminum material is most preferable. Moreover, although not shown in figure, the part which contact | connects the foaming molded product design surface of a plunger, and the surface of the stopper 27 are good also as an uneven | corrugated shape in order to make it easy to pass vapor | steam.

  Next, a first preferred embodiment of the present invention will be described with reference to FIGS.

  FIG. 5 shows the front end of the main pipe portion in a state in which the plunger 6 moves forward and the filling port is closed by the plunger 6 when the plunger is closed. A plunger seal 8 is mounted on the plunger 6 to form a gap 22 that opens toward the foam molded product design surface surrounded by the plunger 6, the plunger seal 8, and the front pipe 21. In the first preferred embodiment of the present invention, the gap 22 is provided with a communication portion for communicating from the outer surface of the front pipe 21. By setting it as such a structure, it can be set as the structure by which the vapor | steam of the front pipe 21 outer surface passes along a communicating part, and is ejected toward the foaming molded product from the clearance gap part 22. FIG.

  FIG. 5 shows a form in which a hole-shaped communication hole 28 is formed as the communication part. The opening position of the steam passage is not limited to the tip side of the plunger seal 8, and the diameter and number of the holes of the steam passage are not particularly limited as long as the strength of the front pipe 21 can be maintained.

  FIG. 6 shows a form in which a groove is provided on the side surface of the front pipe 21 as a communication portion, that is, a slit groove 29 is formed. In particular, FIG. 6 is formed so as to leave the portion of the front pipe 21 in contact with the design surface of the foam molded product, and the position of the opening on the inner surface of the front pipe 21 is the plunger packing 8 for preventing vapor intrusion into the filling machine. However, there are no other restrictions such as restrictions on the opening of the outer surface of the front pipe 21 and the opening width, and if the strength and shape of the front pipe 21 can be maintained, the slit groove is increased. It is preferable to increase the cross-sectional area of the steam channel.

  The gap width of the gap 22 is preferably 0.1 mm or greater and 1.0 mm or less, and more preferably 0.2 mm or greater and 0.5 mm or less. When the gap width is narrow, the steam passage is narrowed and the expected effect of improving the fusion property may not be obtained. Further, when the gap width is increased more than necessary, the trace of the gap remains clearly on the surface of the foamed molded product, and the surface beauty may be impaired.

  FIG. 7 shows another example in which the slit groove 29 is formed so as to include the design surface of the foam molded product of the front pipe 21 as another example of providing the slit groove. The width of the slit groove 29 is preferably 0.1 mm or greater and 1.0 mm or less, and more preferably 0.2 mm or greater and 0.5 mm or less. When the width of the slit groove is narrow, the steam passage is narrowed, and the expected improvement in fusion properties may not be obtained. Moreover, when it enlarges more than necessary, a clearance mark will remain clearly on the surface of the foamed molded product, and the surface aesthetics may be impaired. Since the slit groove mark can vary depending on the magnification of the pre-expanded particles and the resin type, the shape of the slit groove is preferably determined according to the use of the foam molded product. At this time, it is preferable that the width of the slit groove is increased within a range that satisfies the surface standard of the foamed molded product, and is set to a dimension that secures the steam channel cross-sectional area by increasing the number of slit grooves.

  According to a second preferred embodiment of the present invention, the space inside the plunger and the gap that is open toward the design surface surrounded by the plunger, the plunger seal, and the front pipe are communicated through the plunger communication portion. That is.

  That is, as shown in FIG. 8, the steam on the outer surface of the front pipe 21 is connected to the communication portion (the communication hole 28 or the communication hole 28 or , The slit groove 29), and enters the gap portion 22, and can be introduced into the space portion 23 inside the plunger 6 from the gap portion 22 through the plunger communication portion 26. It is possible to more easily increase the temperature of the surface in contact with the surface, and to prevent poor fusion due to overfilling.

  The third preferred embodiment of the present invention is a further improvement of the second preferred embodiment. As shown in FIGS. 9 and 10, the plunger foam molded article design from the space portion 23 inside the plunger 6. A small hole 24 communicating with the surface in contact with the surface is formed, and the small hole 24 formed in the distal end surface of the plunger is smaller than the diameter of the pre-expanded particle. That is, the steam can be ejected from the space 23 provided in the plunger 6 toward the foamed molded product. With this configuration, the steam on the outer surface of the front pipe 21 passes through the communication portion (the communication hole 28 or the slit groove 29), passes through the gap portion 22, and the space inside the plunger 6 from the plunger communication hole 26. Vapor can be ejected from the small holes 24 to the portion that is supplied to the portion 23 and is likely to deteriorate the fusion due to overfilling. Furthermore, since the steam smoothly flows in the plunger, the temperature of the plunger 6 can be easily increased, and there is a tendency that the fusion failure due to overfilling can be effectively prevented as compared with the second preferred embodiment.

  The third preferred embodiment of the present invention will be described more specifically. FIG. 9 shows a configuration in which a through hole is provided from the side surface of the plunger 6 so that a space portion 23 is provided inside the plunger, and a small hole 24 is provided in the space portion 23. The diameter of the small hole 24 is preferably 0.5 mm or more and 2.0 mm or less, and more preferably 1.0 mm or more and 1.5 mm or less. When the diameter of the small hole 24 is small, the area for ejecting steam cannot be secured, and the expected effect of improving fusion may not be obtained. In addition, when the diameter of the small hole 24 is large, there may be a case where a trace of the small hole remains clearly in the foamed molded product after molding and a good appearance cannot be obtained. In FIG. 9, the small holes 24 for ejecting steam are arranged in a row, but there is no problem even if they are arranged in two or three rows depending on the shape of the plunger 6 or the shape of the space portion 23, and the obtained foam is obtained. From the viewpoint of an increase in the amount of jetted steam, it is preferable to make the total cross-sectional area of the small holes 24 as large as possible within the allowable range of the surface beauty of the molded product.

  The material of the plunger 6 is more preferably an aluminum material in order to reduce the heat capacity. Furthermore, it is preferable to subject the plunger surface to anodization to form an aluminum oxide film from the viewpoint of durability because the surface hardness is increased.

  FIG. 10 shows a configuration in which the plunger 6 is cut from the sliding direction of the plunger 6, a space 23 is formed inside the plunger, and steam is ejected from the space via a core vent. According to the form of FIG. 10, the processing for providing the space portion 23 is facilitated by cutting the plunger from the sliding portion direction, and the material change of the core vent 25 is also easy. The material of the core vent is not particularly limited, but an aluminum material is preferable because the heat capacity is further reduced.

  Finally, the most preferred embodiment of the present invention is shown in FIG. The filling machine has the same shape as in FIG. 1, the outer pipe 19 of the main pipe section 3 is made of brass with an overall length of 200 mm and an outer diameter of 35 mm, and the front pipe 21 is made of brass and has a length of 50 mm in consideration of steam erosion. It was used. Six slit grooves 29 for introducing steam from the outer surface of the front pipe 21 into the gap between the front pipe 21 and the plunger 6 are arranged in the circumferential direction, the width of the slit groove is 0.5 mm, and is formed on the outer surface of the front pipe. The slit groove length was 30 mm. This is because the front pipe tip is inserted into the casting by the casting thickness when the filling machine is set in the mold, and steam supply from the outer surface of the front pipe is hindered. Therefore, by making the slit groove longer than this for the casting thickness of 15 mm to 20 mm, the steam on the outer surface of the front pipe can be efficiently supplied to the tip of the plunger.

  The plunger 6 was made of aluminum, the outer diameter was adjusted to 19 mm, and the gap 22 between the front pipe 21 and the plunger 6 was adjusted to 0.5 mm. The tip of the plunger 6 is cut in the plunger sliding direction, the inner diameter of the space 23 is φ10 mm, and an aluminum core vent 25 having an outer diameter φ10 mm for steam injection and a steam groove width 0.5 mm is embedded therein. The jar surface was anodized for the purpose of improving durability.

  The plunger communicating portion 26 for communicating the plunger space 23, the plunger 6 and the gap portion 22 between the front pipe 21 has eight holes of φ1.5 mm along the circumferential direction from the plunger outer peripheral portion to the space portion. Evenly arranged.

  Using this filling machine, confirmation was made about the fusing property and the beauty of the design surface according to the present invention. As a conventional filling machine to be compared, a general-purpose filling machine having no steam ejection function from the plunger tip was used. As the pre-expanded particles, polypropylene 30 times black (trade name LBK30) manufactured by Kaneka Co., Ltd. is used. Air is injected into the pre-expanded particles using a pressurized tank, and the air pressure in the pre-expanded particles is set to an absolute pressure of 0. The one raised to 2 MPa was used. As a molding machine for evaluation, a KD-345 molding machine manufactured by DAISEN Co., Ltd. was used, and a mold having a plate shape of 40 mm thickness of 300 mm × 400 mm was used. In order to compare the overfilling prevention performance of both filling machines, the molding conditions are fixed for 3 seconds for the preheating process, 1 second for the heating process, 4 seconds for the reverse heating process, and the steam pressure for both-side heating is also gauge pressure. The overfilling prevention effect of the present invention was verified by evaluating the surface property and the fusing property of the contact portion between the filling machine and the foamed molded product when the heating time of the double-sided heating process was changed.

  The evaluation criteria are five stages, 5: a good state in which the bead grains are clogged and fused, 4: a slight state between the bead grains is seen, but a relatively good condition, 3: a remarkable appearance is observed between the bead grains. However, the evaluation was made in a state where the beads were fused and did not peel (good quality lower limit quality), 2: the beads were not fused and peeled and failed, and 1: the molded article could not retain its shape. The evaluation part of the foamed molded product is a contact part with a filling machine where poor fusion is likely to occur, and an aluminum casting contact part where high fusion and surface properties will be obtained even with short heating, By comparing the two, the effect of the present invention was further evaluated. Table 1 shows the molding evaluation results.

  As shown in Table 1, in the comparison of the same double-sided heating time, the present invention surpasses the surface property and the fusing property of the conventional filling machine under all conditions. Furthermore, it can be seen that the present invention is superior in terms of surface properties and fusion properties in comparison with the contact portion with the casting. In particular, there is a marked improvement effect in maintaining the surface properties and fusing properties when the double-sided heating time is shortened, and in addition to stabilizing the quality of foamed molded products, steam reduction that leads to energy saving can be achieved. Recognize.

DESCRIPTION OF SYMBOLS 1 Core part 2 Cylinder part 3 Main pipe part 4 Straight pipe 5 Branch pipe 6 Plunger 7 O-ring 8 Plunger seal 9 Rear cover 10 Piston 11 Airport (plunger close)
12 Airport (plunger open)
13 Front cover 14 Rod 15 Air nozzle 16 O-ring 17 Cylinder pipe 18 Airport (filling air)
DESCRIPTION OF SYMBOLS 19 Outer pipe 20 Inner pipe 21 Front pipe 22 Crevice part 23 Space part 24 Small hole 25 Core vent 26 Plunger communication part 27 Plug 28 Communication hole 29 Slit groove

Claims (7)

  A mold having a main pipe part filled with pre-expanded particles in a mold, a cylinder part for reciprocating a plunger in the main pipe part, and a trunk part having a branch pipe part for receiving the pre-expanded particles and supplying them to the main pipe part A filling machine for foaming, wherein a space is provided inside the plunger.   2. A communicating portion that is formed when the plunger is closed and that is surrounded by the plunger, the plunger seal, and the front pipe and that is open toward the foam molded product design surface is provided with a communicating portion that communicates from the outer surface of the front pipe. The filling machine described in.   The space part inside a plunger and the clearance gap part open | released toward the design surface enclosed with the plunger, the plunger seal, and the front pipe were connected through the plunger communication part. Filling machine.   4. The filling machine according to claim 3, wherein a communication hole is formed from the space inside the plunger to the plunger design surface, and the communication hole formed in the plunger design surface is smaller than a pre-foamed particle diameter. .   The filling machine according to claim 4, wherein the plunger is made of an aluminum material.   The filling machine according to claim 5, wherein the communication hole formed in the design surface of the plunger is formed by a core vent.   The filling machine according to claim 6, wherein the core vent is made of an aluminum material.

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