JP2012035469A - Method for molding foamed resin molded body and apparatus of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a foamed resin molded body which avoids generation of recessed marks or the like caused by remaining gas and exhibits an excellent appearance in a method for molding the foamed resin molded body using a counter pressure method for injection filling with a foamed resin material while suppressing foaming of the foamed resin material by injecting a gas into a cavity and by gas pressure of the same.SOLUTION: The foamed resin material is injection-filled while the gas pressure in the cavity 13 is held constant by injecting the gas into the cavity 13, and during immediately before completion of the injection filling or completion thereof to starting foaming, the gas pressure in the cavity 13 is gradually decreased to an ordinary pressure by making a gradual suction force act in the cavity 13 through a gas forcible venting passage 28 having a porous member 29 consisting of a sintered metal or a sintered ceramic on an opening end part facing the inside of the cavity 13, to smoothly all the remaining gas in the cavity 13.

Description

  The present invention is an interior part of an automobile using a counter pressure method in which gas is injected into a cavity of a molding die and the foamed resin material is injected and filled into the cavity while suppressing foaming of the foamed resin material by the gas pressure. The present invention relates to a method for molding a foamed resin molded body such as a door trim and a molding apparatus therefor.

  For example, a method described in Patent Document 1 is known as a method of foaming a foamed resin material that is injected and filled into a cavity of a molding die by an injection machine using a counter pressure method. This injection molding method is arranged in the mold when the foamed resin material is injected and filled into the cavity after injecting the gas into the cavity from the gas supply / discharge mechanism simultaneously with the mold clamping. The pressure in the cavity is detected by the pressure sensor, and the pressure in the cavity is controlled by operating the on / off valve of the gas supply / discharge mechanism so that the above pressure becomes the specified pressure by the signal. Injecting and filling the foamed resin material with a stable injection speed while suppressing the foaming of the resin material, and after the filling is completed, the residual gas in the cavity is rapidly eliminated through the gas supply / discharge mechanism by the vacuum pump and the molding die The movable mold is made to recede by a small stroke for foaming.

JP 2005-153446 A

  In the injection molding method by the counter pressure method, the foaming resin material injected and filled in the cavity is injection-molded while suppressing the foaming by the gas pressure injected into the cavity. After the filling of the material, the gas remains so as to surround the foamed resin material between the inner surface of the mold forming the cavity and the foamed resin material filled in the cavity.

  In order to eliminate the residual gas, in the injection molding method, after the filling of the foamed resin material into the cavity is completed, the residual gas in the cavity is rapidly sucked and removed by the vacuum pump through the gas supply / discharge mechanism. However, if the gas pressure in the cavity is suddenly changed from high pressure to normal pressure in this way, the foamed resin in the vicinity of the exhaust port is caused by the suction force from the exhaust port of the gas passage facing the cavity. A part of the surface of the material bulges and deforms toward the inner surface of the mold, preventing ventilation to the exhaust port, making it impossible to smoothly suck and eliminate the residual gas present in the part away from the exhaust port. There is a problem in that a part of the remaining gas pool causes a dent (sink) on the surface of the product, resulting in poor appearance and a reduction in commercial value.

  The present invention has been made in view of such problems. The object of the present invention is to inject a gas into the cavity and suppress the foaming of the foamed resin material by the gas pressure. In a molding method of a foamed resin molding using a counter pressure method for injection filling, a molding method capable of obtaining a foamed resin molding exhibiting an excellent appearance by eliminating the occurrence of dents due to residual gas and the method are provided. To provide an apparatus for carrying out.

  In order to achieve the above object, according to the method for molding a foamed resin molding of the present invention, a gas supply is performed after clamping a molding die composed of a fixed die and a movable die as described in claim 1. By controlling the amount of gas injected into the cavity through the passage and the amount of gas discharged from the cavity through the gas discharge passage, the foamed resin material is placed in the cavity while maintaining a constant gas pressure in the cavity. In the molding method of the foamed resin molding using the counter pressure method for injection filling, a large number of openings are opened at the end of the cavity between the injection filling of the foamed resin material into the cavity and the start of foaming of the foamed resin material. Residual gas in the cavity is removed through the forced gas exhaust passage equipped with a porous member having fine pores, and the gas pressure in the cavity is gradually reduced to normal pressure. The features.

  In the method of molding a foamed resin molded body configured as described above, the invention according to claim 2 is configured such that gas is supplied from a gas supply source through a gas supply passage into the cavity, and the gas in the cavity is injected and filled into the cavity. By detecting the gas pressure in the cavity with a pressure sensor and controlling the gas supply amount and the gas discharge amount in the cavity while discharging through the gas discharge passage according to the resin pressure of the foamed resin material. The gas pressure is adjusted to a pressure at which the foamed resin material can be injected and filled into the cavity with a predetermined injection pressure while suppressing foaming of the foamed resin material, and after the supply of gas from the gas supply source is stopped, Residual gas in the cavity is gradually removed through the forced gas exhaust passage.

  Furthermore, the invention according to claim 3 is characterized in that the porous member provided at the open end of the forced gas discharge passage facing the cavity is a sintered metal or a sintered ceramic.

  According to a fourth aspect of the present invention, there is provided an apparatus for carrying out the above-mentioned method for molding a foamed resin molded article, wherein a foamed resin material is injected and filled into a cavity of a molding die comprising a fixed mold and a movable mold. In a molding apparatus for producing a foamed resin molding by foaming, an air supply passage having a gas passage communicating with one end of the cavity in the molding die and having an air supply valve provided outside the die, A pressure sensor is connected to and connected to an exhaust passage having an exhaust valve, and a pressure sensor for detecting the gas pressure in the cavity and controlling the gas pressure in the cavity to a predetermined value by the detection signal is provided. In the molding die, a forced gas exhaust passage communicating with a forced exhaust source provided outside the die via an exhaust valve is provided, and the opening end of the forced gas exhaust passage faces the cavity. At this open end Characterized in that it provided a porous member made of a sintered metal or sintered ceramic having a number of micropores.

  In the molding apparatus for a foamed resin molded body configured as described above, the invention according to claim 5 provides the gas passage in the fixed mold and the gas forced discharge passage in the movable mold. The opening end provided with the porous member of the discharge passage faces the central part between both ends of the cavity, and the end surface of the porous member facing the cavity is flush with the inner surface of the mold forming the cavity. It is characterized by being formed on a smooth surface.

  According to the first aspect of the invention, the counter pressure method is used in which gas is injected into the cavity of the molding die and the foamed resin material is injected and filled into the cavity while suppressing the foaming of the foamed resin material by the gas pressure. In the molding method of the foamed resin molded body, the cavity is formed through the gas forced exhaust passage from the injection filling of the foamed resin material into the cavity and immediately before the foaming of the foamed resin material before foaming the foamed resin material injected into the cavity. Residual gas inside is gently removed and the gas pressure in the cavity is gradually reduced to normal pressure, so the surface of the foamed resin material injected and filled in the cavity is pressurized to suppress foaming of the foamed resin material. The open end of the gas forced exhaust passage is made to flow smoothly toward the open end of the gas forced exhaust passage. Flip able to reliably discharged, you are possible to produce a molded article which exhibits excellent appearance which is not occurring, such as boil gas pocket 凹跡 the surface.

  At this time, since the porous member is provided at the opening end of the gas forced exhaust passage that opens toward the cavity, the residual gas in the cavity is forcibly sucked and removed on the gas forced exhaust passage side. Even if an intake force from an exhaust source such as a vacuum pump is applied, the intake force is dispersed in a large number of fine holes in the porous member, and a large number of fine holes facing the cavity due to the ventilation resistance of the fine holes The suction force from the opening end of the mold can be reduced, and the residual resin remains between the surface of the foam resin material and the inner surface of the mold without deforming the foam resin material injected and filled in the cavity by the suction force. The gas can be smoothly flowed to the porous member side by the suction force until it reaches every corner in the cavity, and can be discharged to the gas forced exhaust passage side through the porous member.

  According to the second aspect of the invention, the gas is supplied from the gas supply source into the cavity through the gas supply passage, and the gas in the cavity is supplied according to the resin pressure of the foamed resin material injected and filled into the cavity. While discharging through the gas discharge passage, the gas pressure in the cavity is detected by a pressure sensor, and the inside of the cavity is adjusted to a predetermined gas pressure by controlling the gas supply amount and the gas discharge amount into the cavity. Therefore, it is possible to perform injection filling without causing a foaming reaction of the foamed resin material in the cavity and maintaining an injection speed in a stable state while suppressing an excessive increase in the resin pressure.

  In the invention according to claim 1, the invention according to claim 3 is a sintered metal or sintered ceramic as a porous member disposed at the opening end of the gas forced exhaust passage facing the cavity. Therefore, it is possible to obtain an accurate exhaust port structure in which a large number of fine holes having a substantially uniform hole diameter penetrate through the end surface facing the cavity and the end surface facing the gas forced exhaust passage side, Residual gas in the cavity is gradually removed while suctioning the residual gas in the cavity uniformly from the numerous fine holes provided in these sintered metals or ceramics, and the gas pressure in the cavity is changed from high pressure to normal pressure. The slope of the pressure drop to the surface can be smoothed, and therefore, as described above, a product excellent in commercial value with no dents on the surface can be obtained.

  Further, as an apparatus for carrying out the molding method of the foamed resin molding, as described in claim 4, a gas passage communicating with one end of the cavity is provided in the molding die, and the gas passage is used as a mold. It is connected to and communicated with an air supply passage having an air supply valve provided outside and an exhaust passage having an exhaust valve, and the gas pressure in the cavity is detected by the detection signal and the gas pressure in the cavity is set to a predetermined value. As described above, the pressure sensor for controlling the pressure sensor is fed back to the air supply passage having the air supply valve and the exhaust passage having the exhaust valve to feed the detection signal from the molding machine to the cavity. It is possible to perform injection filling into the cavity while suppressing foaming of the foamed resin material injected and filled therein and maintaining the injection speed of the foamed resin material in a stable state.

  In addition to this exhaust passage, a gas forced exhaust passage communicating with a forced exhaust source such as a vacuum pump provided outside the mold via an exhaust valve is provided in the molding die. Since the opening end of the passage faces the cavity and a porous member made of sintered metal or sintered ceramic having a large number of fine holes is provided at the opening end portion, a powerful intake force from a forced exhaust source Is reduced by the ventilation resistance of a large number of micropores in the porous member, and the suction force is dispersed in these micropores so that the residual gas in the cavity is relatively weak from the open end of the micropore facing the cavity. Suction can be performed with the intake force, and by adjusting the opening of the exhaust valve, the intake air amount can be adjusted and the intake gas can be accurately adjusted so that the residual gas in the cavity can be sucked and removed within a predetermined time. thing Therefore, as described above, the gas pressure in the cavity can be gradually reduced from high pressure to normal pressure, and all residual gas remaining in the cavity can be removed and then foamed to the surface. It is possible to stably produce a molded product of uniform quality in which no defective portion such as a dent is generated.

  Further, according to the invention according to claim 5, the gas passage for holding the pressure in the cavity at a constant pressure at the time of injection filling by the counter pressure method, the air supply passage having the air supply valve communicated with the gas passage, and the exhaust Since an exhaust passage having a valve is provided on the fixed mold side and a gas forced discharge path is provided in the movable mold, the pressure in the cavity can be maintained at a constant pressure during injection filling by the counter pressure method. By providing the above-mentioned gas forced discharge passage in an existing molding apparatus equipped with a gas passage, etc., it is improved to a device capable of producing a high-quality molded product in which a defective portion such as a dent due to residual gas does not occur on the surface. Can do.

  Further, since the end face of the porous member provided at the open end of the gas forced discharge passage facing the cavity is formed on the smooth surface flush with the inner face of the mold forming the cavity, the foamed resin material When foamed, the surface pressed against the end surface of the porous member can be finished to the same clean surface as the surface pressed against the inner surface of the mold, and further, an opening provided with the porous member of the gas forced discharge passage Since the end faces the center between both ends of the cavity, the residual gas in the cavity can be sucked and removed evenly and efficiently from the center of the cavity toward both ends in the cavity. Residual gas can be eliminated, and all residual gas in the cavity can be smoothly and reliably eliminated in a short time.

The simplified vertical side view of an injection foaming mold. FIG. 3 is a chart showing a press chart of a molding process from mold clamping to mold opening and a gas pressure state in the mold corresponding to the press chart. The diagram which shows the relative relationship of the injection pressure of a foamed resin material, the injection speed, and gas pressure. Explanatory drawing which shows the state which is supplying the gas in a cavity. Explanatory drawing which shows the state which has excluded gas from the inside of a cavity. Explanatory drawing which shows the state which is excluding gas through a gas forced discharge passage.

  Next, a specific embodiment of the present invention will be described with reference to the drawings. In FIG. 1, a molding die 10 includes a stationary die 11 provided with a recess for forming a cavity 13, and the stationary die. 11 includes a movable mold 12 that is slidably inserted into a recess of 11 and forms the cavity 13 between the mating surfaces with the fixed mold 11, and is injected from the injection machine 14 into the fixed mold 11. A gate 21 for injecting and filling the foamed resin material in the molten state into the cavity 13 is provided, and is provided in one end portion of the fixed mold 11 on the mating surface with the movable mold 12 on one end side of the cavity 13. A gas passage 22 communicating with the inside of the cavity 13 through a groove (not shown) is provided. The gas passage 22 is branched outside the mold, one of which is a gas supply passage 23 formed of a pipe or a hose, and the other is the same. It is connected to the gas discharge passage 24 consisting of a pipe or a hose. , It is communicated.

  Further, the gas supply passage 23 and the gas discharge passage 24 are provided with an air supply control valve 25 and an exhaust control valve 26, respectively, and the gas supply passage 23 is an air supply comprising a gas cylinder filled with an inert gas. Connected to source 27.

  On the other hand, the movable mold 12 is provided with a gas forced discharge passage 28 for actively sucking and removing the residual gas in the cavity 13 in addition to the gas passage 22 provided in the fixed mold 11. There is an opening at one end of the gas forced discharge passage 28 having a diameter larger than that of the passage, and the opening end faces the central portion between both ends of the cavity 13 and faces inside the opening. The porous member 29 made of sintered metal or sintered ceramic provided with a large number of micropores is disposed by fitting, and the smooth end face of the porous member 29 facing the cavity 13 is movable metal The gas inside the cavity 13 can be discharged to the gas forced discharge passage 28 through a large number of fine holes directed to the cavity 13 so as to be flush with the surface of the mold 12.

  The other end opening of this gas forced discharge passage 28 provided in the movable mold 12 is connected to and communicated with an out-mold gas forced discharge passage 30 consisting of a pipe or hose piped outside the mold. An exhaust control valve 31 is provided in the gas forced exhaust passage 28, and the out-of-mold gas forced exhaust passage 28 having the exhaust control valve 31 is connected to an exhaust source 32 including a vacuum pump.

  Further, pressure sensors 33 for detecting the gas pressure in the cavity 13 are arranged at a plurality of locations around the cavity 13 in the fixed mold 11 and the movable mold 12, and signals from these pressure sensors 33 are provided. Is supplied to a control device (not shown) and the signal is fed back to the gas supply passage having the air supply control valve 25 and the gas exhaust passage having the exhaust control valve 26 via the control device. The control valve 25 and the exhaust control valve 26 are operated to adjust the supply and discharge amounts of gas to the cavity 13 so that the inside of the cavity 13 has a predetermined pressure. Further, the molding apparatus is provided with the above-described control apparatus and timer (not shown) having a control circuit corresponding to a time schedule from mold clamping to mold opening. In the following, the exhaust control valve on the side of the gas discharge passage 24 connected to and communicated with the gas passage 22 provided in the fixed mold 11 will be referred to as a first exhaust control valve 26, and the out-of-mold gas forced discharge passage 28 will be described. The exhaust control valve provided in FIG. 2 will be described as a second exhaust control valve 31.

  A method of molding a foamed resin molded product such as a door trim, which is an interior part of an automobile, using the molding apparatus configured as described above will be described with reference to FIGS. 2 to 6. First, the movable mold in the molding mold 10 is described. Clamping is performed by moving 12 to the fixed mold 11 side from the mold opening position A to the mold clamping position B shown in FIG. As soon as the mold clamping is completed, a timer is started and each part is controlled through the control device.

  When the mold clamping is completed, the air supply control valve 25 is opened as shown in FIG. 4, and the inert gas enters the gas passage 22 provided in the fixed mold 11 from the air supply source 17 through the gas supply passage 23. Gas is supplied and injected into the cavity 13 from the gas passage 22. Note that the first exhaust control valve 26 and the second exhaust control valve 31 are closed during the gas injection.

  The gas pressure injected into the cavity 13 from the supply source 17 through the gas supply passage 23 and the gas passage 22 is constantly detected by a plurality of pressure sensors 33, and the gas pressure in the cavity 13 is When the pressure reaches a set pressure equivalent to a gas pressure that suppresses foaming of the foamed resin material injected and filled in the cavity 13 and allows the foamed resin material to be injected and filled into the cavity 13 at a constant injection speed. The air supply control valve 25 is closed via the control device in response to a signal from the sensor 33, and at the same time, the polypropylene resin or the like kneaded with the foaming agent is melted from the injector 14 through the gate 21 provided in the fixed mold 1. A foamed resin material made of resin is injected and filled into the cavity 3 with a predetermined injection pressure. In FIG. 2, C is the injection filling start position into the cavity 13, and D is the filling completion position.

  When the foamed resin material is injected and filled into the cavity 13 from the injection machine 14, the gas pressure in the cavity 13 rises above the set pressure, and this rise is detected by the pressure sensor 33. As shown in FIG. 5, the first exhaust control valve 26 is opened by the signal through the control device, and an amount of gas corresponding to the injection filling amount of the foamed resin material into the cavity 13 is sent from the cavity 13 to the gas passage 22. The gas is discharged through the gas discharge passage 24. At this time, if the gas discharge amount is large and the gas pressure in the cavity 13 becomes lower than the set pressure, the supply control valve 25 is opened and the gas is injected into the cavity 13 to reach the predetermined pressure. Return.

  In this way, the pressure in the cavity 13 is detected by the pressure sensor 33, and the signal is fed back to the air supply control valve 25 and the first exhaust control valve 26, thereby controlling the inside of the cavity 13 to the set pressure. Injection filling of the foamed resin material into the cavity 13 is performed. FIG. 3 shows the gas pressure in the cavity 13 from the start of injection filling of the foamed resin material into the cavity 13 and immediately before the start of foaming, and the fluctuation state of the injection speed and injection pressure of the foamed resin material.

  In this way, the resin foam material is injected and filled into the cavity 13, and immediately before the injection filling is completed or at the completion of the injection filling, the air supply control valve 25 and the exhaust control valve 26 are closed, as shown in FIG. By opening the second exhaust control valve 31 provided in the discharge passage 30, residual gas remaining between the surface of the foamed resin material in the cavity 13 and the inner surface of the mold facing the cavity 13 is eliminated. .

  Specifically, immediately after the injection filling of the foamed resin material into the cavity 13 is completed or just before the completion, the second exhaust control valve 31 provided in the out-of-mold gas forced discharge passage 30 is opened and the exhaust source 32 including a vacuum pump is operated. When the second exhaust control valve 31 is opened, the intake force by the exhaust source 32 acts on the gas forced exhaust passage 28 provided in the movable mold 12 through the out-of-mold gas forced exhaust passage 30. The suction force is applied to the cavity 13 through a large number of fine holes in the porous member 29 provided at the tip of the gas forced discharge passage 28 and facing the cavity 13, and the surface of the foamed resin material and the cavity 13 Residual gas remaining between the inner surface of the mold facing the inside is sucked into the gas forced exhaust passage 28 through the numerous fine holes of the porous member 29, and the exhaust gas forced exhaust passage 30 through the exhaust gas forced exhaust passage 30 side. To eliminate.

  At this time, the intake force from the exhaust source 32 can be dispersed by a large number of fine holes in the porous member 29 and can be reduced by the ventilation resistance of the fine holes. Further, the second exhaust control valve 31 is opened. By controlling the degree, the suction force can be adjusted, and therefore the suction force from all the fine holes opening toward the inside of the cavity 13 becomes gentle and the foamed resin injected and filled into the cavity 13 Foamed resin material while maintaining the state in which the space part in which the residual gas remains is communicated toward the porous member 29 without causing deformation such as a bulge that blocks the exhaust gas due to the suction force of the material. All the residual gas can flow smoothly toward the porous member 29 along the surface of the mold and the inner surface of the mold, and can be sucked and eliminated through the fine holes of the porous member 29, and the gas pressure in the cavity can be reduced. The pressure can be gradually reduced to normal pressure. In addition, since the porous member 29 faces the central portion of the cavity 13, it is possible to efficiently suck and remove the residual gas to every corner of the cavity 13 in a short time.

  Thus, from the completion of the injection filling of the foamed resin material into the cavity 13 or immediately before the completion of foaming of the foamed resin material (position E in FIG. 2), from the gas forced discharge passage 28 provided with the porous member 29. After the residual gas in the cavity 13 is removed through the gas forced discharge passage 30 outside the mold and the gas pressure in the cavity 13 is reduced to normal pressure, the movable mold 12 is made minute from position E to F in FIG. The foamed resin material is foamed by retreating only by the stroke, and in that state, the foamed resin material is cooled from F to G to complete the foaming, and then the mold is opened (G-H in FIG. 2) to obtain the foamed resin molded body. Demold. In the above embodiment, the gas forced discharge passage 28 is provided on the movable mold 12 side, but the porous member 29 provided on the fixed mold 11 side and provided at the front end opening is provided in the cavity 13. It may be a structure facing the surface.

10 Mold
11 Fixed mold
12 Movable mold
13 cavity
14 Injection machine
21 Foam resin material madness passage
22 Gas passage
23 Gas supply passage
24 Gas exhaust passage
25 Air supply valve
26 First exhaust valve
27 Air supply source
28 Gas forced exhaust passage
29 Porous material
30 Outlet gas forced exhaust passage
31 Second exhaust valve
32 Exhaust source
33 Pressure sensor

Claims (5)

  After clamping a molding die consisting of a fixed die and a movable die, the amount of gas injected into the cavity through the gas supply passage and the amount of gas discharged from the cavity through the gas discharge passage are controlled. In the molding method of the foamed resin molding using the counter pressure method in which the foamed resin material is injected and filled into the cavity while maintaining the inside of the cavity at a constant gas pressure, the injection of the foamed resin material into the cavity is performed. During the start of foaming of the foamed resin material, the residual gas in the cavity is removed through the gas forced exhaust passage provided with a porous member having a large number of micropores at the end opened in the cavity, and the gas pressure in the cavity A method for molding a foamed resin molded article, wherein the pressure is gradually reduced to normal pressure.   Gas is supplied from the gas supply source into the cavity through the gas supply passage, while the gas in the cavity is discharged through the gas discharge passage according to the resin pressure of the foamed resin material injected and filled into the cavity. By controlling the gas supply amount and gas discharge amount into the cavity by detecting the pressure with a pressure sensor, the gas pressure in the cavity is controlled to a predetermined injection pressure while suppressing foaming of the foamed resin material. The pressure is adjusted so that the cavity can be injected and filled, and after the supply of gas from the gas supply source is stopped, the residual gas in the cavity is gradually removed through the forced gas discharge passage. 2. A method for molding a foamed resin molded article according to 1.   The foamed resin molded article according to claim 1 or 2, wherein the porous member provided at the opening end of the gas forced exhaust passage facing the cavity is a sintered metal or a sintered ceramic. Molding method.   In a molding apparatus for producing a foamed resin molding by injecting and filling a foamed resin material into a cavity of a molding die composed of a fixed die and a movable die, and communicating with one end of the cavity in the molding die The gas passage is connected to and communicated with an air supply passage having an air supply valve and an exhaust passage having an exhaust valve provided outside the mold, and the gas pressure in the cavity is detected. A pressure sensor is provided for controlling the gas pressure in the cavity to a predetermined value based on the detection signal, and is further communicated with a forced exhaust source provided outside the mold via an exhaust valve. The gas forced exhaust passage is provided so that the open end of the gas forced exhaust passage faces the cavity, and a porous member made of sintered metal or sintered ceramic having a large number of fine holes is provided at the open end. Have Molding apparatus of the foamed resin molded article according to claim.   The gas passage is provided in the fixed mold, the gas forced discharge passage is provided in the movable mold, and the opening end portion where the porous member of the gas forced discharge passage is provided in the central portion between both ends of the cavity. The foamed resin molding according to claim 4, wherein the end surface of the porous member facing the cavity is formed on a smooth surface flush with the inner surface of the mold forming the cavity. Body shaping device.

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