JP2010064368A - Injection molding apparatus and injection molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an injection-molded product without quality degradation caused by resin burning by carrying out molding within a case substituted with non-oxidizing gas. <P>SOLUTION: This injection molding apparatus 10 has an injection molding machine 12 disposed in the case 13. The injection molding apparatus 10 includes: an air supply pipe 58 and an exhaust pipe 60 provided at the case 13; and a non-oxidizing gas generator 14 supplying nitrogen gas (N<SB>2</SB>) into the case 13 from the air supply pipe 58. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an injection molding apparatus and an injection molding method for molding a molded product using an injection molding machine.

Conventionally, when a molded product is molded using an injection molding machine, a non-oxidizing gas such as nitrogen gas (N ₂ ) is supplied to the resin path from the hopper to the screw in the injection cylinder as a countermeasure against resin burning. A technique for preventing resin burn due to mixing is known (see, for example, Patent Document 1).

  Since the resin is a petroleum product, it deteriorates when heat is applied and eventually carbonizes (for example, the resin staying in the injection cylinder is thermally deteriorated and carbonized). Moreover, high temperature resin is oxidized by contact with air, and further deteriorates.

That is, when the resin is heated too much, the resin is oxidized, and when the resin is oxidized, the viscosity is lowered and the surface of the resin is changed to brown.
Japanese Patent No. 3282900

However, in Patent Document 1, even though resin burning on the injection unit side can be prevented, there is no effect on resin burning caused by oxidation on the mold side or residual oxygen during setup of the molding apparatus.
For this reason, there has been a demand for a technique for preventing resin burn caused by oxidation not only on the injection unit side but also on the mold side.

  The present invention has been made to solve such a problem, and an injection molding apparatus capable of obtaining an injection molded product free from quality deterioration due to resin burning by molding in a casing replaced with a non-oxidizing gas. And it aims at providing the injection molding method.

In order to achieve the object, the invention according to claim 1
In an injection molding apparatus in which an injection molding machine is arranged in a housing,
A gas introduction hole and a gas discharge hole provided in the housing;
And a non-oxidizing gas supply means for supplying a non-oxidizing gas into the casing from the gas introduction hole.

The invention according to claim 2 is the injection molding apparatus according to claim 1,
It has the ventilation unit which circulates non-oxidizing gas in the said housing | casing, It is characterized by the above-mentioned.
The invention according to claim 3 is the injection molding apparatus according to claim 1 or 2,
It has a partition which divides the inside of the case into a plurality of gas tanks.

The invention according to claim 4 is the injection molding apparatus according to any one of claims 1 to 3,
The partition is partitioned so that a gas tank in which the injection molding machine is arranged is in a blown state from one direction.

The invention according to claim 5 is the injection molding apparatus according to any one of claims 1 to 4,
Oxygen concentration measuring means for measuring the oxygen concentration in the housing;
Control means for controlling the amount of non-oxidizing gas supplied into the housing and the amount discharged from the housing based on the output of the oxygen concentration measuring means.

The invention according to claim 6
In the injection molding method by the injection molding machine arranged in the housing,
Filling the inside of the housing with a non-oxidizing gas;
And a step of forming a molded product after filling the inside of the housing with a non-oxidizing gas.

The invention according to claim 7 is the injection molding method according to claim 6,
In the molding step, the oxygen concentration in the casing is set to 2% or less.

  ADVANTAGE OF THE INVENTION According to this invention, the injection molded product without quality deterioration by resin baking can be obtained by shape | molding in the housing | casing substituted by the nonoxidizing gas.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 is a cross-sectional front view of an injection molding apparatus 10-1 according to the first embodiment.

  This injection molding apparatus 10-1 is non-oxidizing as non-oxidizing gas supply means for supplying a non-oxidizing gas (for example, nitrogen gas) into the casing 13 and an injection molding machine 12 disposed in the casing 13. And a reactive gas generator 14. The housing 13 surrounds the entire injection molding machine 12 and is formed airtight with respect to the external atmosphere. The injection molding machine 12 is supported by the base 11.

  The injection molding machine 12 includes an injection mold 16, an injection unit 18, and a mold clamping unit 20. The injection mold 16 is for molding the injection-filled molten resin into a desired shape, and is opened and closed in the mold opening / closing direction (XX direction) by the mold clamping unit 20. The injection unit 18 plasticizes the resin and performs transfer, kneading, melting, etc., and injects a predetermined amount into the injection mold 16.

  In the above, the injection mold 16 has the fixed mold 24 and the movable mold 26 that are opposed to each other across the parting line (PL), the fixed platen 29 that supports the fixed mold 24, and the movable mold 26 that supports the movable mold 26. A side platen 33 is provided. The fixed side platen 29 and the movable side platen 33 are integrally connected and fixed by a tie bar 34.

  The movable platen 33 can be moved by the mold clamping unit 20 in the mold opening / closing direction (XX direction). A cavity 74 is formed between the fixed mold 24 and the movable mold 26 in the mold clamping state.

  The injection unit 18 includes a hopper 44 as a resin supply unit, a kneading / injection driving unit 46, and a melting / kneading unit 48. In the hopper 44, a granular (pellet-shaped) molding material (for example, a cycloolefin polymer) is accommodated. The melting / kneading unit 48 includes a screw 52. In addition, a heater 54 for heating the molding material is incorporated on the outer peripheral side of the screw 52.

  The non-oxidizing gas generator 14 is, for example, a gas cylinder or the like, and serves to supply a non-oxidizing gas (for example, nitrogen gas) into the housing 13. The housing 13 is provided with an air supply pipe 58 as a gas introduction hole and an exhaust pipe 60 as a gas discharge hole. An air supply valve 59 is provided in the air supply pipe 58, and an exhaust valve 61 is provided in the exhaust pipe 60.

At the time of molding, the molded product is molded after the inside of the housing 13 is filled with nitrogen gas by supplying nitrogen gas (N ₂ gas) from the non-oxidizing gas generator 14. In this case, the molding is performed in a state where the oxygen concentration in the housing 13 is 2% or less.

  According to the experiment, when the presence or absence of foreign matter was examined using a cycloolefin polymer (resin having a transition point of 136 ° C.) at a heating temperature of 260 ° C., the resin was colored at an oxygen concentration of 5%, and the oxygen concentration This is because the resin was slightly colored at 3%, and when the oxygen concentration was 2% or less, the resin was not colored.

Next, the operation of this embodiment will be described.
In FIG. 1, prior to injection molding, the fixed mold 24 and the movable mold 26 are in a mold open state in which they are separated with a parting line (PL) interposed therebetween. In this state, the inside of the housing 13 is replaced with nitrogen gas. For this purpose, the air supply valve 59 and the exhaust valve 61 are opened, and nitrogen gas is sent from the non-oxidizing gas generator 14 into the housing 13. Thus, the air supply valve 59 and the exhaust valve 61 are closed when the air in the housing 13 is replaced with nitrogen gas.

  Next, the fixed mold 24 and the movable mold 26 are brought into close contact with a parting line (PL) to perform mold clamping. At this time, the cavity 74 formed by the fixed mold 24 and the movable mold 26 is in a state of being replaced with nitrogen gas. Thus, the screw 52 in the melting / kneading unit 48 is advanced, and the molding material is injected from the sprue 75 into the cavity 74.

At this time, since the inside of the cavity 74 is replaced with nitrogen gas, it does not oxidize even at the moment when the injected molding material is injected, thereby preventing resin burn.
Thereafter, the molding material in the cavity 74 is held at a predetermined pressure, and then cooled to a predetermined temperature. Further, the fixed mold 24 and the movable mold 26 are opened, and the molded product 73 (see FIG. 7) is released.

Finally, the molded product 73 (see FIG. 7) that has been released by a take-out device (not shown) is taken out.
In the present embodiment, for example, a ventilation unit may be provided in the housing 13 and the nitrogen gas in the housing 13 may be circulated by the ventilation unit. In this way, a uniform atmosphere can be created. Further, after the nitrogen gas replacement, the intake valve 59 and the exhaust valve 61 may be formed without closing. By doing so, an increase in oxygen concentration can be reliably suppressed. The molded product thus molded can be taken out by, for example, a take-out device (not shown) arranged in the housing 13.

According to this embodiment, the inside of the housing 13 is filled with nitrogen gas or the like by including the non-oxidizing gas generator 14 that supplies nitrogen gas or the like from the air supply pipe 58 provided in the housing 13. Since the injection molding is performed, oxygen does not remain in the mold. For this reason, it is possible to prevent the resin as the molding material from being oxidized. Thereby, it is possible to obtain a molded product that is clean and free from resin burning.
[Second Embodiment]
FIG. 2 is a cross-sectional front view of the injection molding apparatus 10-2 according to the second embodiment. In addition, the same code | symbol is attached | subjected and demonstrated to the member which is the same as that of 1st Embodiment, or corresponds.

The injection molding apparatus 10-2 has a partition wall 22 for partitioning the inside of the housing 13 to the first tank 43 ₁ and the second tank 43 ₂ as a gas tank. The first tank 43 ₁ is arranged injection molding machine 12. The first tank 43 ₁ and the second tank 43 ₂ Two vents 21 and 23 for communicating is provided in the partition wall 22. Further, the vent hole 23, second tank 43 ₂ of the nitrogen gas _{(N 2} gas) can blown into the first tank 43 ₁ a blower unit 76 is provided.

Accordingly, the nitrogen gas in the second vessel 43 in the _2, the blower unit 76 is blown toward the first tank 43 ₁ in the direction of the arrow A, further, the nitrogen gas in the first tank 43 in ₁ through the vent 21 It flows into the second tank 43 ₂ in the direction of arrow B Te. In this way, the inside of the housing 13 is in a state of blowing air from one direction, and an atmosphere with a uniform low oxygen concentration is maintained in the room.

  The blower unit 76 includes a filter 77 that removes dust and an ionizer 78 that generates ions for removing static electricity generated during mold release. The molded product 73 that has been molded can be taken out, for example, by a take-out device (not shown) arranged in the housing 13.

According to the present embodiment, the nitrogen gas in the housing 13 can be circulated in one direction by the blower unit 76. Thereby, the gas retention part in the housing | casing 13 can be eliminated and a uniform nitrogen atmosphere can be formed in a short time. Furthermore, by performing injection molding under such a nitrogen atmosphere, a molded product that is clean and free from resin burn can be obtained.
[Third Embodiment]
FIG. 3 is a cross-sectional front view of an injection molding apparatus 10-3 according to the third embodiment. In addition, the same code | symbol is attached | subjected and demonstrated to the member which is the same as that of 1st Embodiment, or corresponds.

  In the injection molding apparatus 10-3 of the present embodiment, a branch pipe 79 is attached to the exhaust pipe 60 in the injection molding apparatus 10-2 of FIG. 2, and an oxygen concentration meter 80 as an oxygen concentration measuring means is attached to the end of the branch pipe 79. Is installed. The oxygen concentration meter 80 can measure the oxygen concentration in the housing 13.

A control unit 82 is attached as a control means capable of adjusting the throttle of the supply valve 59 and the exhaust valve 61 based on the oxygen concentration detected by the oxygen concentration meter 80. This control unit 82 can automatically adjust the amount of nitrogen gas (N ₂ gas) supplied into the housing 13 and the amount discharged from the housing 13.

Thus, when the oxygen concentration rises above a predetermined value, the air supply valve 59 is opened and a predetermined amount of nitrogen gas is supplied into the housing 13.
In the present embodiment, the oxygen concentration meter is used because the concentration of oxygen that directly causes resin burning can be detected. Moreover, the molded product 73 (refer FIG. 7) shape | molded can be taken out with the taking-out apparatus not shown arrange | positioned in the housing | casing 13, for example.

According to the present embodiment, since the oxygen concentration meter 80 and the control unit 82 are connected between the air supply valve 59 and the exhaust valve 61, the supply amount of nitrogen gas according to the increase in the oxygen concentration in the housing 13. By adjusting the above, the oxygen concentration in the housing 13 can be maintained with a small amount of nitrogen gas supplied. Further, by circulating the nitrogen gas inside the housing 13, the gas retention portion can be eliminated and a uniform nitrogen atmosphere can be obtained in a short time. Thereby, it is possible to obtain a molded product that is clean and free from resin burning.
[Fourth Embodiment]
4 to 7 are cross-sectional front views of the injection molding apparatus 10-4 of the fourth embodiment to which the take-out device 15 is added. Except for the take-out device 15, the other configuration is the same as that shown in FIG. Further, the same or corresponding members as those in the first embodiment will be described with the same reference numerals.

FIG. 4 is a cross-sectional front view of the mold clamping process of the injection molding apparatus 10-4.
The take-out device 15 in the injection molding apparatus 10-4 has a guide stay 62, and is movable and rotatable in the mold opening direction (XX direction) and in the direction orthogonal to the mold opening direction (from the front surface to the back surface in FIG. 4). It has a free transfer robot 63, a take-out arm 66 attached to the transfer robot 63, and a chuck 70 attached to the tip of the take-out arm 66.

Prior to molding, firstly opened and the air supply valve 59 of the exhaust valve 61, feed the nitrogen gas from the first tank 43 ₁ and the second tank 43 ₂ in a non-oxidizing gas generator 14 in the housing 13. Thus, the inside of the housing 13 is replaced with nitrogen gas. At this time, by driving the blower unit 76, the inside of the housing 13 can be replaced quickly and evenly. Further, the oxygen concentration meter 80 and the control unit 82 are set so that, for example, the oxygen concentration in the housing 13 is 2% or less.

  This is because, as described above, when the oxygen concentration is 2% or less, the resin is not colored even under heating. That is, when the oxygen concentration in the housing 13 approaches 2% from a state of 2% or less, nitrogen gas is automatically supplied into the housing 13. In this way, the oxygen concentration in the housing 13 is controlled so as not to exceed 2%.

This gas replacement is performed with the fixed mold 24 and the movable mold 26 opened. This is because gas replacement is performed so that oxygen does not remain in the cavity 74.
In this state, the mold clamping unit 20 is driven to move the movable mold 26 toward the fixed mold 24 to bring them into close contact with each other. Thus, the movable mold 26 and the fixed mold 24 are clamped with the parting line (PL) interposed therebetween. In this state, the cavity 74 and the sprue 75 are filled with nitrogen gas.

Next, FIG. 5 is a sectional front view of the injection process.
In this step, the screw 52 in the melting / kneading unit 48 is advanced to the mold (24, 26) side, and the molding material is injected from the sprue 75 into the cavity 74. At this time, since the inside of the cavity 74 is replaced with nitrogen gas, the injected molding material is not oxidized even under heating. Thus, resin burning of the molding material is prevented.

Thereafter, the molding material in the cavity 74 is held at a predetermined pressure, and then cooled to a predetermined temperature.
In the above process, the oxygen concentration in the housing 13 is controlled so as not to exceed 2%. That is, the throttle of the air supply valve 59 and the exhaust valve 61 is automatically controlled by the oxygen concentration meter 80 and the control unit 82.

Next, FIG. 6 is a cross-sectional front view of the weighing / releasing process.
In this step, the screw 52 in the melting / kneading unit 48 moves backward toward the kneading / injection drive unit 46. Thus, a predetermined amount of resin is stored in the storage chamber 84. Further, the mold clamping unit 20 moves the movable mold 26 in the mold opening direction (leftward direction of XX) with respect to the fixed mold 24 to release the molded product 73.

Next, FIG. 7 is a sectional front view of the process of taking out the molded product 73.
In this step, the molded product 73 remains on the movable mold 26 in the mold open state (see FIG. 6). Therefore, the take-out arm 66 of the take-out device 15 is moved, and the molded product 73 is gripped by the chuck 70. The gripped molded product 73 is placed on a pallet (not shown) or a conveyor and is carried out to the outside.

According to the present embodiment, since the molded product 73 after the release is taken out by the take-out device 15 arranged in the housing 13, the atmosphere in the housing 13 can always be maintained in a state where nitrogen gas is replaced. it can. By performing injection molding in such an environment, it is possible to obtain a molded product 73 that is clean and free from resin burning.
[Fifth Embodiment]
FIG. 8 is a sectional front view of an injection molding apparatus 10-5 according to the fifth embodiment. In addition, the same code | symbol is attached | subjected and demonstrated to the member which is the same as that of 1st Embodiment, or corresponds.

The injection molding apparatus 10-5, the housing 13 is divided into three first partition wall 22 ₁ and the second partition wall 22 _2. That is, the first tank 43 ₁ the injection molding machine 12 is arranged, the first partition wall 22 ₁ in the four vents ₂₃ 1-23 ₄ each vent hole ₂₃ 1-23 ₄ each air blowing unit provided 76 and the second tank 43 ₂ provided that has a third tank 43 ₃ which is partitioned, the the first tank 43 ₁ and ventable second partition 22 _2.

Incidentally, the injection molding machine 12 is supported by the elastic plate 88 in the first tank 43 _1. Further, the ₂ second partition 22 a number of vent holes 25 are formed.
Further, at the side in the housing 13, by a partition wall 86 which extends vertically, return passage 87 which communicates the second chamber 43 ₂ and the third tank 43 ₃ in the vertical direction is formed. The return path 87 is partitioned from the first chamber 43 ₁ the injection molding machine 12 is arranged.

The return path 87, the nitrogen gas in the second tank 43 in ₂ is fed to the first tank 43 ₁ by the blowing unit 76, also, the nitrogen gas in the first tank 43 ₁ is sent to the third tank 43 ₃ . Furthermore, the nitrogen gas of the third tank 43 ₃ is returned to the second tank 43 ₂ through the return channel 87.

Thus, according to this embodiment, the inside housing 13 and 3 tank structure, the injection molding machine 12 forms a stream of nitrogen gas only from one direction in the first tank 43 _1, which is arranged, nitrogen Generation | occurrence | production of the residence part of gas can be prevented.

Further, in the present embodiment, by which the first partition wall 22 ₁ in the blower unit 76 is disposed, it is possible to the first tank 43 1 _to the third tank 43 ₃ to a uniform flow of nitrogen. Moreover, the oxygen concentration in the housing 13 can be suppressed to a predetermined value or less with a small air volume. In addition, since the flow of the nitrogen atmosphere is uniform, the air volume hitting the injection molding machine 12 is reduced, and the temperature distribution of the mold when the injection molding machine 12 is cooled can be reduced.

Furthermore, in this embodiment, since molding is performed in a uniform nitrogen atmosphere, oxygen does not remain in the injection mold 16. For this reason, oxidation of the resin as the molding material can be prevented, and a molded product that is clean and free from resin burn can be obtained.
[Sixth Embodiment]
FIG. 9 is a sectional front view of an injection molding apparatus 10-6 according to the sixth embodiment. In addition, the same code | symbol is attached | subjected and demonstrated to the member which is the same as that of 1st Embodiment, or corresponds.

The injection molding apparatus 10-6 of this embodiment is obtained by connecting an oxygen concentration meter 90 and a control unit 92 to the injection molding apparatus 10-1 of the first embodiment.
That is, in this embodiment, the branch pipe 91 is provided in the exhaust pipe 60 of nitrogen gas (N ₂ gas), and the oxygen concentration meter 90 is attached to the end of the branch pipe 91. By doing so, the oxygen concentration in the housing 13 can be measured by the oxygen concentration meter 90. Further, by adjusting the throttles of the supply valve 59 and the exhaust valve 61 based on the oxygen concentration detected by the oxygen concentration meter 90, the amount of nitrogen gas supplied into the housing 13 and the exhaust from the housing 13 are exhausted. The amount can be adjusted automatically.

According to the present embodiment, without providing a blower unit in the housing 13, the amount of nitrogen gas is adjusted according to the increase in oxygen concentration, thereby reducing the amount of oxygen in the housing 13 with a small amount of nitrogen supply. A concentration atmosphere can be maintained.
[Seventh Embodiment]
FIG. 10 is a sectional front view of an injection molding apparatus 10-7 according to the seventh embodiment, and FIG. 11 is a plan view thereof. In addition, the same code | symbol is attached | subjected and demonstrated to the member which is the same as that of 1st Embodiment, or corresponds.

  In the present embodiment, the injection molding apparatus 10-7 has a take-out device 15 in the vicinity of the injection molding machine 12, and this take-out apparatus 15 has a feature in that it has a suction member 94 instead of the chuck 70. Have.

  That is, the take-out device 15 includes a guide stay 62, a transfer robot 63 that is movable and rotatable in a mold opening direction (XX direction) and a direction orthogonal to the guide opening direction (XX direction). The take-out arm 66 attached to the transfer robot 63 and the suction member 94 attached to the tip of the take-out arm 66 are provided.

  A pallet 72 on which a molded product 73 (see FIG. 7) is placed is arranged on the rail 71 laid on the bottom of the housing 13. The other configuration is the same as that of the injection molding apparatus 10-4 shown in FIG.

  In the present embodiment, the released molded product 73 remains on the movable mold 26 as shown in FIG. 6, but this molded product is taken out by vacuum suction using the suction member 94. Further, the removed molded product is placed on the pallet 72 and conveyed outside along the rail 71.

  According to this embodiment, the take-out device 15 has the suction member 94, and the molded product is taken out by vacuum suction with the suction member 94, so that it does not require strict positioning accuracy like the chuck 70, It can be removed safely and reliably.

  Moreover, in the present embodiment, since the take-out device 15 is arranged in the housing 13, the atmosphere in the housing 13 can be always maintained in a state where nitrogen gas is replaced. By molding in such an environment, it is possible to obtain a molded product that is clean and free from resin burning.

It is a section front view of the injection molding device of a 1st embodiment. It is a section front view of the injection molding device of a 2nd embodiment. It is a section front view of the injection molding device of a 3rd embodiment. It is a section front view of the injection molding device of a 4th embodiment. It is a section front view of the injection molding device of a 4th embodiment. It is a section front view of the injection molding device of a 4th embodiment. It is a section front view of the injection molding device of a 4th embodiment. It is a section front view of the injection molding device of a 5th embodiment. It is a section front view of the injection molding device of a 6th embodiment. It is a section front view of the injection molding device of a 7th embodiment. It is a top view same as the above.

Explanation of symbols

10-1 Injection molding apparatus 10-2 Injection molding apparatus 10-3 Injection molding apparatus 10-4 Injection molding apparatus 10-5 Injection molding apparatus 10-6 Injection molding apparatus 10-7 Injection molding apparatus 11 Base 12 Injection molding machine 13 Housing Body 14 Non-oxidizing gas generator 15 Removal device 16 Injection mold 18 Injection unit 20 Clamping unit 21 Vent 22 Partition ₁ 22 _First partition 22 _2nd partition 23 Vent 24 Fixed mold 25 Vent 26 movable mold 28 fixed side block member 29 fixed side platen 33 movable side platen 34 tie bar 43 ₁ first tank 43 ₂ second tank 43 ₃ third tank 44 hopper 46 kneading / injection drive unit 48 melting / kneading unit 52 screw 54 Heater 58 Air supply pipe 59 Air supply valve 60 Exhaust pipe 61 Exhaust valve 66 Extraction arm 70 Chuck 71 Rail 72 Pallet 73 Molded product 74 Cavity 75 Spru 76 Blow unit 77 Filter 78 Ionizer 79 Branch pipe 80 Oxygen meter 82 Control part 84 Storage chamber 86 Partition 87 Recirculation path 88 Elastic plate 90 Oxygen meter 91 Branch pipe 92 Control part 94 Adsorption member

Claims (7)

In an injection molding apparatus in which an injection molding machine is arranged in a housing,
A gas introduction hole and a gas discharge hole provided in the housing;
Non-oxidizing gas supply means for supplying non-oxidizing gas from the gas introduction hole into the housing. The injection molding apparatus according to claim 1, further comprising a ventilation unit that circulates a non-oxidizing gas in the housing. The injection molding apparatus according to claim 1, further comprising a partition wall that partitions the housing into a plurality of gas tanks. The said partition is divided so that the gas tank in which the said injection molding machine is arrange | positioned will be in the ventilation state from one direction. The injection molding apparatus in any one of Claims 1-3 characterized by the above-mentioned. Oxygen concentration measuring means for measuring the oxygen concentration in the housing;
5. Control means for controlling the amount of non-oxidizing gas supplied into the housing and the amount discharged from the housing based on the output of the oxygen concentration measuring means. An injection molding apparatus according to any one of the above. In the injection molding method by the injection molding machine arranged in the housing,
Filling the inside of the housing with a non-oxidizing gas;
A step of filling the inside of the housing with a non-oxidizing gas and then forming a molded product. An injection molding method comprising: The injection molding method according to claim 6, wherein in the molding step, the oxygen concentration in the casing is set to 2% or less.