CN110234489B - Injection molding method and injection molding apparatus - Google Patents
Injection molding method and injection molding apparatus Download PDFInfo
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- CN110234489B CN110234489B CN201880008936.5A CN201880008936A CN110234489B CN 110234489 B CN110234489 B CN 110234489B CN 201880008936 A CN201880008936 A CN 201880008936A CN 110234489 B CN110234489 B CN 110234489B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/72—Heating or cooling
- B29C45/73—Heating or cooling of the mould
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
- B29C45/17—Component parts, details or accessories; Auxiliary operations
- B29C45/76—Measuring, controlling or regulating
- B29C45/78—Measuring, controlling or regulating of temperature
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- Manufacturing & Machinery (AREA)
- Mechanical Engineering (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
Abstract
A heat medium passage (30) and a cooling medium passage (32) are formed in a movable core (14) as a mold. A heating medium supplied from a heating thermostat (34) through a heating medium supply line (36) and a cooling medium supplied from a cooling thermostat (38) through a cooling medium supply line (40) flow through the heating medium passage (30) and the cooling medium passage (32), respectively. A heat medium circulation line (54) for returning the heating medium to the heating thermostat (34) and a refrigerant circulation line (62) for returning the cooling medium to the cooling thermostat (38) are connected to the heat medium supply line (36) and the refrigerant supply line (40), respectively.
Description
Technical Field
The present invention relates to an injection molding method and an injection molding apparatus for obtaining a resin molded product by cooling and solidifying a molten resin material injected into a cavity (cavity) formed by a mold.
Background
Injection molding is a well-known method for obtaining a resin molded product from a molten resin material. In this case, a molten resin material is injected into a cavity formed by a mold. The molten resin material is thereby deformed into a shape corresponding to the shape of the cavity, and in this state, the molten resin material is cooled and solidified in the cavity. Then, the mold is opened to take out the resin molded article having a shape corresponding to the shape of the cavity.
In the case where the temperature needs to be changed depending on the molding site, a site having a high temperature and a site having a low temperature are formed in the mold, in other words, a temperature difference is set. For example, in the conventional technique described in japanese patent application laid-open No. 7-68614, a heat medium passage and a refrigerant passage are provided in a mold, heating oil (a heating medium, a heating agent, and a heat medium) is circulated through the heat medium passage at a molding portion where high temperature is required, and cooling water (a cooling medium, a cooling agent, and a refrigerant) is circulated through the refrigerant passage at a molding portion where low temperature is required.
Disclosure of Invention
In order to mass-produce resin molded articles on an industrial scale, it is required to shorten tact time. Therefore, for example, it is proposed to increase the cooling and solidification speed of the molten resin material by circulating a cooling medium through the refrigerant passage during cooling and solidification.
However, in the conventional technique described in japanese patent application laid-open No. 7-68614, a molding portion requiring a high temperature (a region where a heat medium passage is formed) and a molding portion requiring a low temperature (a region where a refrigerant passage is formed) are separated by a heat insulating material to prevent the both regions from being affected. Therefore, even if the cooling medium is circulated during cooling solidification, it is difficult to increase the cooling rate of the region where the heat medium passage is formed. Thus, in the conventional technique, the disadvantage that the tact time is not easily shortened is revealed.
The main object of the present invention is to provide an injection molding method which can easily increase the cooling rate of a molten resin material.
Another object of the present invention is to provide an injection molding apparatus capable of achieving a reduction in tact time.
According to one embodiment of the present invention, there is provided an injection molding method for obtaining a resin molded product by injecting a molten resin material and cooling and solidifying the same, the injection molding method including a cavity forming step, an injection step, a cooling step, and a discharging step,
forming a cavity by using a mold provided with a heat medium passage through which a heating medium for heating the molten resin material flows and a cooling medium passage through which a cooling medium for cooling the molten resin material flows;
in the injection step, the molten resin material is supplied to the cavity while the heating medium, whose temperature is adjusted by a heating temperature adjuster and which is supplied through a heat medium supply line, is circulated through the heat medium passage;
in the cooling step, after the injection molding is completed, the communication between the heat medium supply line and the heat medium passage is blocked, the heating medium is enclosed in the heat medium passage, while the heating medium supplied from the heating thermostat to the heat medium supply line is returned to the heating thermostat via a heat medium circulation line provided in the heat medium supply line, and the cooling medium whose temperature is regulated by the cooling thermostat is circulated through the refrigerant passage, thereby cooling the molten resin material in the cavity;
in the discharging step, after the cooling is completed, the flow of the cooling medium through the refrigerant passage is stopped, and the cooling medium in the refrigerant passage is discharged by a discharge fluid.
That is, in the present invention, since the heating medium is circulated through the heat medium passage to heat the molten resin material in the cavity in the injection step, the molten resin material maintains fluidity until the filling of the cavity with the molten resin material is completed. Therefore, the molten resin material is prevented from losing fluidity during the injection molding process, or an unfilled portion is prevented from being formed in the cavity due to the loss of fluidity.
In the cooling step, on the other hand, the cooling medium is circulated through the cooling medium passage to cool the molten resin material in the cavity. This increases the cooling rate of the molten resin material. Therefore, the time (takt time) from the injection of the molten resin material until the resin molded product is obtained is shortened. Thus, the resin molded article can be efficiently produced, and mass production on an industrial scale is easily achieved.
In the cooling step, the heating medium is returned to the heating thermostat to maintain the heating medium at a predetermined temperature. Therefore, the heating medium having reached a sufficient temperature can be supplied to the mold when the injection step in the next injection molding is performed. Further, as the heating medium is resupplied to the heat medium supply line, the heating medium immediately flows through the heat medium passage. According to the above, since the temperature of the mold rapidly rises, the time from the start of mold opening to the injection step can be shortened.
In addition, in the cooling step, the heating medium is enclosed in the heat medium passage. That is, in this case, after the injection step is completed, the heating medium is not discharged from the heat medium passage. Therefore, the injection step can be quickly shifted to the cooling step, and the tact time required for injection molding can be further shortened. Further, since the cooling capacity of the cooling medium is larger than the heating capacity of the heating medium, the temperature of the mold can be sufficiently lowered in the cooling step even in a state where the heating medium is enclosed in the heat medium passage.
And, before the heating medium is resupplied into the mold, the cooling medium is discharged with the discharge fluid. Therefore, the refrigerant is discharged from the refrigerant passage, and therefore, the refrigerant is prevented from reaching a boiling point and generating vapor when the heating medium is resupplied.
Preferably, during the injection step, the cooling medium is returned to the cooling thermostat via a refrigerant circulation line provided in a refrigerant supply line for supplying the cooling medium from the cooling thermostat to the refrigerant passage. This makes it possible to maintain the state in which the temperature of the cooling medium is sufficiently lowered. Therefore, the cooling medium maintained at the predetermined temperature can be quickly supplied to the mold during the cooling step. That is, the injection step can be immediately switched to the cooling step, and the cooling rate of the molten resin material can be sufficiently increased.
Further, it is preferable that the cooling medium is returned to the cooling thermostat through the refrigerant circulation line during the discharge step for the same reason as described above.
Oil and water can be cited as preferable examples of the heating medium and the cooling medium, respectively. In this case, even in a state where the oil seal is in the heat medium passage as described above, the temperature of the mold can be sufficiently lowered by passing water through the refrigerant passage.
In addition, according to another embodiment of the present invention, there is provided an injection molding apparatus for obtaining a resin molded product by injecting a molten resin material and cooling and solidifying the same, the injection molding apparatus including a mold, a heating temperature regulator, a heat medium supply line, a heat medium circulation line, a 1 st switching valve, a cooling temperature regulator, a refrigerant supply line, a controller, and a discharge fluid supply source,
a mold that forms a cavity to which the molten resin material is supplied, and that is provided with a heat medium passage through which a heating medium that heats the molten resin material flows and a refrigerant passage through which a cooling medium that cools the molten resin material flows;
the temperature regulator for heating controls the temperature of the heating medium;
the heating medium supply line supplies the heating medium from the heating thermostat into the heating medium passage;
the heating medium circulation line branches off from the heating medium supply line and is used for returning the heating medium to the heating thermostat;
the 1 st switching valve selectively brings the heat medium supply line into a communication state or a communication blocking state with the heat medium passage or the heat medium circulation line;
the temperature regulator for cooling controls the temperature of the cooling medium;
the refrigerant supply line supplies the cooling medium from the cooling thermostat to the refrigerant passage;
the controller is configured to switch from a state in which the heating medium flows through the heat medium passage to a state in which the cooling medium flows through the refrigerant passage, and to switch from a state in which the cooling medium flows through the refrigerant passage to a state in which the heating medium flows through the heat medium passage;
the discharge fluid supply source supplies a discharge fluid for discharging the cooling medium in the refrigerant passage.
According to this configuration, the heating medium is circulated through the heat medium passage to heat the molten resin material in the cavity, the cooling medium is circulated through the cooling medium passage to cool the molten resin material in the cavity, and the heating medium is enclosed in the heat medium passage during the cooling, while the heating medium supplied from the heating thermostat to the heat medium supply line is returned to the heating thermostat to maintain the heating medium at a predetermined temperature. Therefore, it is possible to prevent the molten resin material from losing fluidity during injection or forming unfilled portions in the cavity due to the loss of fluidity, and to reduce the tact time from the start of injection of the molten resin material to the time when a resin molded product is obtained, and to reduce the time from the start of mold opening to the time when the injection step is performed.
When the controller switches from a state in which the cooling medium flows through the cooling medium passage to a state in which the heating medium flows through the heating medium passage, the discharge fluid is supplied. Accordingly, since the cooling medium is discharged from the cooling medium passage, the generation of vapor of the cooling medium at a boiling point in the mold when the heating medium is supplied is avoided.
Preferably, the injection molding apparatus is provided with a refrigerant circulation line branched from the refrigerant supply line and returning the cooling medium to the cooling thermostat. This makes it easy to maintain the cooling medium at a predetermined temperature. Therefore, when the cooling medium is needed, the cooling medium having a sufficiently low temperature can be quickly supplied. In this case, the 2 nd switching valve may be provided to selectively bring the refrigerant supply line into a communication state or a communication blocking state with the refrigerant passage or the refrigerant circulation line.
Further, when the heating medium flows through the heat medium passage, the cooling medium may be returned to the cooling thermostat via the refrigerant supply line and the refrigerant circulation line. Accordingly, the cooling medium is prevented from reaching the boiling point by the heat from the heating medium and from being vaporized into steam.
For the same reason, it is preferable that the cooling medium is returned to the cooling thermostat via the refrigerant supply line and the refrigerant circulation line even when the cooling medium in the refrigerant passage is discharged by the discharge fluid. In the above, preferable examples of the oil and water as the heating medium and the cooling medium are given.
According to the present invention, the mold is provided with the heat medium passage and the refrigerant passage, and the heating medium is made to flow through the heat medium passage when the fluidity of the molten resin material is ensured, while the cooling medium is made to flow through the refrigerant passage when the molten resin material filled in the cavity is cooled and solidified. Therefore, it is possible to prevent the molten resin material from losing fluidity during injection or forming unfilled portions in the cavity due to this, and it is possible to shorten the takt time from the injection of the molten resin material to the obtaining of the resin molded product.
In addition, when the cooling medium flows through the refrigerant passage, the heating medium is returned to the heating thermostat. Therefore, the heating medium can be maintained at a predetermined temperature, and the time from the start of mold opening to the injection step can be shortened.
Drawings
Fig. 1 is a longitudinal sectional view of a main part of an injection molding apparatus according to an embodiment of the present invention.
Fig. 2 is a schematic view showing the flow paths of the heating medium and the cooling medium in the cavity forming step and the injection step in the injection molding apparatus of fig. 1.
Fig. 3 is a schematic view showing the flow paths of the heating medium and the cooling medium in the injection molding apparatus of fig. 1 during the cooling step.
Fig. 4 is a schematic view showing the flow paths of the heating medium and the cooling medium in the exhaust step in the injection molding apparatus of fig. 1.
Detailed Description
Hereinafter, an injection molding method according to the present invention will be described in detail with reference to the drawings, taking preferred embodiments in relation to an injection molding apparatus for carrying out the method.
Fig. 1 is a longitudinal sectional view of a main part of an injection molding apparatus 10 according to the present embodiment. The injection molding apparatus 10 has a punch 12, a movable core 14, and a die 16. The punch 12 is a fixed mold, and the movable core 14 and the die 16 are each a movable mold that is displaceable so as to be able to approach or separate from the punch 12.
The punch 12 is provided to a fixed platen 18 positioned and fixed to the table, and has a convex portion 20 protruding toward the movable core 14. On the other hand, the die 16 is formed with a recess 24 recessed from the punch 12 side toward the movable platen 22 side. The movable platen 22 is displaced in a direction to approach or separate from the punch 12 by a displacement mechanism (e.g., a hydraulic cylinder) not shown. The die 16 is also displaced in the same direction following the movable platen 22.
The movable core 14 interposed between the punch 12 and the die 16 is displaceable in a direction perpendicular to the paper surface of fig. 1, for example, by a displacement mechanism such as a hydraulic cylinder, not shown. The movable core 14 is formed in a shape corresponding to the concave portion 24, and the convex portion 20 enters below the movable core 14, wherein the movable core 14 enters into the concave portion 24. Accordingly, the cavity 26 is formed.
A heat medium passage 30 is formed in the movable core 14 at a position close to the cavity 26, and a refrigerant passage 32 is formed at a position facing the recess 24 side so as to be close to the heat medium passage 30. Both the heat medium passage 30 and the refrigerant passage 32 extend in a direction perpendicular to the paper surface of fig. 1.
A heating thermostat 34 (heating thermostat) for supplying a heating medium, i.e., heating oil, is connected to the heat medium passage 30 via a heat medium supply line 36. On the other hand, a cooling thermostat 38 (cooling thermostat) for supplying cooling water as a cooling medium is connected to the refrigerant passage 32 via a refrigerant supply line 40. The heating thermostat 34 and the cooling thermostat 38 are electrically connected to a control circuit 44 (control unit) via signal lines 42a and 42b, respectively. The control circuit 44 controls the heating thermostat 34 and the cooling thermostat 38 via the signal lines 42a and 42b to adjust the temperatures of the heating oil and the cooling water.
As shown in detail in fig. 2, a circuit line 46 is provided between the heating thermostat 34 and the heat medium passage 30. That is, the heating oil supplied from the heating thermostat 34 to the heat medium passage 30 through the heat medium supply line 36 flows through the heat medium passage 30, and then passes through the circuit line 46 and returns to the heating thermostat 34.
A first three-way valve 50 as a switching valve is installed in the heat medium supply line 36, and a diversion line 52 that diverts from the first three-way valve 50 to the circuit line 46 is provided. A heat medium circulation line 54 is formed by the downstream side of the return line 46 and the diversion line 52, and the heat medium circulation line 54 prevents the heating oil from reaching the heat medium passage 30 and returns to the heating thermostat 34. Therefore, the heat medium circulation line 54 branches off from the heat medium supply line 36.
The first three-way valve 50 selectively communicates the heat medium supply line 36 with the heat medium passage 30 or the heat medium circulation line 54, while blocking the communication. That is, when the heating medium supply line 36 is communicated with the heating medium passage 30, the heating medium supply line 36 and the heating medium circulation line 54 are blocked from communicating with each other. In contrast, when the heating medium supply line 36 communicates with the heating medium circulation line 54, the communication of the heating medium supply line 36 with the heating medium passage 30 is blocked.
A first on-off valve 56 is provided on the heat medium supply line 36 downstream of the first three-way valve 50. Further, a second on-off valve 58 is provided on the upstream side of the connection point of the return line 46 with respect to the steering line 52.
On the other hand, a second three-way valve 60 as a switching valve is installed in the refrigerant supply line 40. A refrigerant circulation line 62 for returning the cooling water to the cooling thermostat 38 without reaching the refrigerant passage 32 is connected to the second three-way valve 60. That is, the refrigerant circulation line 62 branches from the refrigerant supply line 40.
The second three-way valve 60 selectively communicates the refrigerant supply line 40 with the refrigerant passage 32 or the refrigerant circulation line 62, and blocks the communication. That is, when the refrigerant supply line 40 communicates with the refrigerant passage 32, the communication between the refrigerant supply line 40 and the refrigerant circulation line 62 is blocked. On the contrary, when the refrigerant supply line 40 communicates with the refrigerant circulation line 62, the refrigerant supply line 40 and the refrigerant passage 32 are blocked from communicating with each other.
A third three-way valve 64 is provided on the refrigerant supply line 40 downstream of the second three-way valve 60. A compressed air source 66 for supplying compressed air is connected to the third three-way valve 64 via an air supply line 68. That is, the gas supply line 68 is communicated with the refrigerant supply line 40 or blocked from communicating with the refrigerant supply line 40 by appropriately setting the opening direction of the third three-way valve 64. The compressed air functions as a discharge fluid for discharging the cooling water from the refrigerant passage 32. In other words, the compressed air source 66 is a discharge fluid supply source.
The first three-way valve 50, the second three-way valve 60, the third three-way valve 64, the first on-off valve 56, and the second on-off valve 58 are operated under the control of the control circuit 44. That is, the control circuit 44 sets the opening directions of the first to third three-way valves 50 to 64, and sets the first and second on-off valves 56 and 58 to the open state or the closed state.
The drain line 70 is connected to the refrigerant passage 32. The cooling water supplied from the cooling thermostat 38 to the refrigerant passage 32 through the refrigerant supply line 40 flows through the refrigerant passage 32, and is then discharged to the outside of the die cavity 16 through the drain line 70. The discharged cooling water may be discharged to a drain tank or the like, or may be returned to the cooling thermostat 38.
In the above configuration, a plurality of injection molding machines, not shown, are provided on the punch 12. The molten resin material 72 injected from each injection molding machine is supplied into the cavity 26 through a runner (runner), a sprue (runner), and a gate (gate) (all not shown).
The injection molding apparatus 10 according to the present embodiment is basically configured as described above, and the operational effects thereof will be described with reference to the relation with the injection molding method according to the present embodiment.
Before the mold closing, heating oil is first supplied to the heat medium passage 30 formed in the movable core 14. Therefore, as shown in fig. 2, the control circuit 44 sets the opening direction of the first three-way valve 50 so that the heating oil flows from the heating medium supply line 36 only in the direction of the heating medium passage 30, and opens both the first on-off valve 56 and the second on-off valve 58. In fig. 2, the open state (or direction) is indicated by "o", the closed state (or direction) is indicated by "x", and the same is true in fig. 3 and 4.
Accordingly, the heating oil adjusted to a predetermined temperature by the heating thermostat 34 flows through the heat medium supply line 36 to the heat medium passage 30. As a result, the movable core 14 rises to a predetermined temperature. The heating oil flowing through the heat medium passage 30 is returned to the heating thermostat 34 through the circuit line 46, and the temperature is readjusted in the heating thermostat 34. Then, the heat medium is resupplied to the heat medium passage 30 through the heat medium supply line 36. That is, at this time, the entire amount of the heating oil is supplied to the heat medium passage 30 and returned to the heating thermostat 34 via the circuit line 46. In other words, the heating oil cannot be returned to the heating thermostat 34 via the diversion line 52 (heat medium circulation line 54).
The control circuit 44 operates the second three-way valve 60 and the third three-way valve 64 together. Specifically, the opening direction of the second three-way valve 60 is set to a direction in which the refrigerant supply line 40 and the refrigerant passage 32 are blocked from communicating with each other and the refrigerant supply line 40 and the refrigerant circulation line 62 are communicated with each other. Therefore, the entire amount of the cooling water is returned from the refrigerant supply line 40 to the cooling thermostat 38 via the refrigerant circulation line 62. In addition, the third three-way valve 64 blocks the communication between the air supply line 68 and the refrigerant supply line 40.
Then, a cavity forming step is performed for injection molding. Specifically, the female die 16 and the movable core 14 are displaced to approach the male die 12 by the displacement mechanisms provided to the movable platen 22 and the movable core 14, respectively. Thereby, the cavity 26 is formed as a closed mold. Since the heat medium passage 30 is closer to the cavity 26 than the refrigerant passage 32, the heat of the heating oil is easily obtained in the cavity 26, and the temperature is easily raised to an appropriate temperature.
Subsequently, an injection molding process is performed. Specifically, the molten resin material 72 is injected from each of the plurality of injection molding machines. The molten resin material 72 is introduced into the cavity 26 by passing through the runner, the sprue, and the plurality of gates in this order. Since the movable core 14 has already been raised to an appropriate temperature by the supply of the heating oil, the molten resin material 72 is appropriately heated. Thus, the molten resin material 72 is difficult to solidify while maintaining a flowable state.
As described above, the cooling water is returned to the cooling thermostat 38 via the refrigerant circulation line 62. Therefore, no cooling water is present in the refrigerant passage 32 in the movable core 14. Therefore, the coolant can be prevented from boiling and evaporating in the refrigerant passage 32.
The molten resin materials 72 injected from the respective injection molding machines converge with each other within the cavity 26, and after the cavity 26 is filled with the molten resin material 72 (in other words, after the molten resin material 72 is filled in the cavity 26), pressure is applied to the molten resin material 72 by at least one of the plurality of gates.
In order to apply the pressure, for example, the molten resin material 72 is injected from the injection molding machine. In this case, in the pressure applying step, a so-called pressure holding step of injecting the molten resin material 72 in an amount corresponding to the shrinkage amount accompanying the solidification of the molten resin material 72 in the cavity 26 can be performed at the same time.
Alternatively, a pin (pin) may be inserted into the gate to apply pressure to the molten resin material 72. Further, a pressing pin may be provided in the die 16 or the punch 12, and the pressing pin may be operated to press the molten resin material 72 in the cavity 26.
Next, a cooling step of cooling the molten resin material 72 in the cavity 26 is performed. Accordingly, the control circuit 44 changes the opening directions of the first and second three- way valves 50 and 60. That is, as shown in fig. 3, the opening direction of the first three-way valve 50 is set such that the heating oil flows only in the direction from the heat medium supply line 36 to the circuit line 46 via the diverter line 52. Accordingly, the communication of the heating medium supply line 36 with the heating medium passage 30 is blocked, and the heating medium supply line 36 communicates with the heating medium circulation line 54. Therefore, the heating oil is returned to the heating thermostat 34 via the heat medium circulation line 54, and the heating oil flowing through the heat medium passage 30 is sealed in the heat medium passage 30.
At the same time, the control circuit 44 controls the first and second switching valves 56 and 58 to be closed. Therefore, the heating oil flowing from the first three-way valve 50 to the transfer line 52 is prevented from flowing back from the second switching valve 58 to the heating medium supply line 36 through the heating medium passage 30.
The opening direction of the second three-way valve 60 is set so that the coolant flows only in the direction from the coolant supply line 40 to the coolant passage 32. That is, the refrigerant supply line 40 communicates with the refrigerant passage 32, and the communication between the refrigerant supply line 40 and the refrigerant circulation line 62 is blocked. Therefore, the entire amount of the cooling water is supplied to the refrigerant passage 32 and is not returned to the cooling thermostat 38 via the refrigerant circulation line 62. Further, the third three-way valve 64 maintains the supply line 68 blocked from the refrigerant supply line 40.
As the cooling water flows through the coolant passage 32, the temperature of the movable core 14 decreases. Therefore, the heat of the molten resin material 72 is extracted by the movable core 14. Therefore, the molten resin material 72 is cooled at a large cooling rate. The molten resin material 72 is solidified by cooling, and as a result, a resin molded product having a shape substantially corresponding to the shape of the cavity 26 can be obtained.
In this way, in the present embodiment, when the molten resin material 72 is cooled, a cooling medium, i.e., cooling water, is supplied to the inside of the movable core 14. Therefore, the cooling rate of the molten resin material 72 can be increased, and the tact time from injection until mold opening (taking out of the resin molded article) can be shortened accordingly.
In this case, since the cooling water is circulated through the refrigerant circulation line 62 in advance, the opening direction of the second three-way valve 60 is changed at a point in time when the cooling water needs to be supplied, and thus the cooling water adjusted to a predetermined temperature can be immediately circulated through the refrigerant passage 32. This also increases the cooling rate of the molten resin material 72, thereby achieving a further reduction in the tact time.
Further, the cooling water is discharged into the drain tank via the drain line 70. Alternatively, the cooling water may be returned from the drain line 70 to the cooling thermostat 38. On the other hand, the state in which the heating oil is sealed in the heat medium passage 30 is maintained. That is, when the injection step is shifted to the cooling step, the heating oil cannot be discharged from the heat medium passage 30. Accordingly, the transition from the injection step to the cooling step can be performed quickly. Further, the cooling capacity of the cooling water is larger than the heating capacity of the heating oil. Therefore, during the cooling process, the temperature of the movable core 14 is sufficiently lowered.
After the molten resin material 72 is solidified to obtain a resin molded product, the mold is opened. At this time, the control circuit 44 controls the first to third three-way valves 50 to 64 to be opened, and the first and second on-off valves 56 and 58 to be opened. That is, as shown in fig. 4, the opening direction of the first three-way valve 50 is set to a direction in which the heat medium supply line 36 is communicated with the heat medium passage 30 and the communication of the heat medium supply line 36 with the heat medium circulation line 54 is blocked. Therefore, the heating oil flows only in the direction from the heating medium supply line 36 to the heating medium passage 30 through the first switching valve 56. Accordingly, the heating oil adjusted to an appropriate temperature by the heating thermostat 34 is circulated and supplied to the heat medium passage 30, as in the injection step.
That is, in the present embodiment, even when the heating oil is not supplied to the heat medium passage 30, the heating oil is circulated through the heat medium circulation line 54 and maintained at a predetermined temperature. Therefore, the heating oil adjusted to the predetermined temperature can be immediately supplied to the movable core 14.
When the heating medium is resupplied to the heat medium supply line 36 from a state in which the heating oil is sealed in the heat medium passage 30, the heating oil immediately starts to flow through the heat medium passage 30. That is, the time from the start of resupply until the heating medium starts to flow through the heat medium passage 30 is short. In interaction with the above, the temperature of the movable core 14 can be raised at a high speed.
In this case, the temperature of the movable core 14 is increased while the mold opening operation is performed. Therefore, the next injection molding can be performed quickly after the mold is opened. In interaction with the above, the time from the opening of the mold until the next injection process is started is shortened.
On the other hand, the opening direction of the second three-way valve 60 is set to a direction in which the refrigerant supply line 40 and the refrigerant passage 32 are blocked from communicating with each other and the refrigerant supply line 40 and the refrigerant circulation line 62 communicate with each other, as in the case of the injection step. Therefore, the cooling water is circulated only in the direction of returning to the cooling thermostat 38 via the refrigerant circulation line 62. The opening direction of the third three-way valve 64 is set to a direction in which the air supply line 68 communicates with the refrigerant supply line 40. As a result, the cooling water is not circulated through the refrigerant supply line 40, and only the compressed air supplied from the compressed air source 66 and passed through the air supply line 68 is circulated.
The compressed air pushes the cooling water in the refrigerant supply line 40 and the refrigerant passage 32 out to the drain line 70. Accordingly, a discharge step of discharging the cooling water is performed, and the refrigerant passage 32 is replaced with compressed air. In this state, since the heating oil is supplied to the heat medium passage 30, the cooling water remaining in the refrigerant passage 32 is prevented from boiling and vaporizing.
In this way, the mold opening is performed while the heating oil is supplied to the heat medium passage 30 and the compressed air is supplied to the refrigerant passage 32 to discharge the cooling water. After the mold opening is completed, the exposed resin molded article is pushed out by an ejector pin (not shown) to be released from the mold. The discharging step may be continued until the completion of the mold release of the resin molded product, or may be completed during the mold opening or the mold release.
Then, the cavity forming step is performed again for the next injection molding. As described above, since the heating oil has already been supplied to the movable core 14, the movable core 14 rises to a predetermined temperature. Thus, injection molding can be performed quickly.
The present invention is not particularly limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.
For example, the mold for forming the heat medium passage 30 and the refrigerant passage 32 is not limited to the formation of the heat medium passage 30 and the refrigerant passage 32 in the movable core 14, and the heat medium passage 30 and the refrigerant passage 32 may be formed in the punch 12 and the die 16, or the heat medium passage 30 and the refrigerant passage 32 may be formed in the entire punch 12, the movable core 14, and the die 16. For example, the heat medium passage 30 may be provided only in the punch 12, and the refrigerant passage 32 may be provided only in the movable core 14 or the die 16.
The injection molding apparatus 10 may be configured without including the movable core 14.
Description of the reference numerals
10: an injection molding device; 12: a male die; 14: a movable core; 16: a female die; 26: a cavity; 30: a heat medium passage; 32: a refrigerant passage; 34: a heating thermostat; 36: a heating medium supply line; 38: a thermostat for cooling; 40: a refrigerant supply line; 44: a control circuit; 46: a loop line; 50: a first three-way valve; 52: a diversion line; 54: a heat medium circulation line; 56: a first on-off valve; 58: a second on-off valve; 60: a second three-way valve; 62: a refrigerant circulation line; 64: a third three-way valve; 66: a source of compressed air; 68: a gas supply line; 70: a drain line; 72: the resin material is melted.
Claims (10)
1. An injection molding method for obtaining a resin molded product by injecting a molten resin material (72) and cooling and solidifying the same, characterized by comprising a cavity forming step, an injection molding step, a cooling step and a discharging step,
in the cavity forming step, a mold (14) provided with a heat medium passage (30) for circulating a heating medium for heating the molten resin material (72) and a cooling medium passage (32) for circulating a cooling medium for cooling the molten resin material (72) is used to form a cavity (26);
in the injection step, the molten resin material (72) is supplied into the cavity (26) while the heating medium, the temperature of which is adjusted by a heating temperature adjuster (34) and which is supplied via a heat medium supply line (36), is circulated through the heat medium passage (30);
in the cooling step, after the injection molding is completed, the communication between the heat medium supply line (36) and the heat medium passage (30) is blocked, the heating medium is sealed in the heat medium passage (30), the heating medium supplied from the heating thermostat (34) to the heat medium supply line (36) is returned to the heating thermostat (34) via a heat medium circulation line (54) provided in the heat medium supply line (36), and the cooling medium whose temperature is regulated by the cooling thermostat (38) is circulated through the cooling medium passage (32), thereby cooling the molten resin material (72) in the cavity (26);
in the discharge step, after cooling is completed, the flow of the cooling medium through the refrigerant passage (32) is stopped, and the cooling medium in the refrigerant passage (32) is discharged by a discharge fluid,
when the injection molding process is performed again after the return from the discharge process to the cavity forming process, the inside of the cooling medium passage (32) is replaced with the discharge fluid, and in this state, the heating medium is supplied to the heating medium passage (30), and the mold (14) is reheated.
2. The injection molding method according to claim 1,
during the injection step, the cooling medium is returned to the cooling thermostat (38) via a refrigerant circulation line (62) provided in a refrigerant supply line (40) that supplies the cooling medium from the cooling thermostat (38) to the refrigerant passage (32).
3. The injection molding method according to claim 2,
during the discharge process, the cooling medium is returned to the cooling thermostat (38) via the refrigerant circulation line (62).
4. An injection molding method according to any one of claims 1 to 3,
oil is used as the heating medium, and water is used as the cooling medium.
5. An injection molding apparatus (10) for obtaining a resin molded product by injecting a molten resin material (72) and cooling and solidifying the same, characterized by comprising a mold (14), a heating temperature regulator (34), a heat medium supply line (36), a heat medium circulation line (54), a 1 st switching valve (50), a cooling temperature regulator (38), a refrigerant supply line (40), a controller (44), and a discharge fluid supply source (66),
the mold (14) is provided with a cavity (26) to which the molten resin material (72) is supplied, and is provided with a heat medium passage (30) through which a heating medium for heating the molten resin material (72) flows and a cooling medium passage (32) through which a cooling medium for cooling the molten resin material (72) flows;
the heating thermostat (34) controls the temperature of the heating medium;
the heat medium supply line (36) supplies the heating medium from the heating thermostat (34) into the heat medium passage (30);
the heat medium circulation line (54) branches off from the heat medium supply line (36) and is used for returning the heating medium to the heating thermostat (34);
the 1 st switching valve (50) selectively putting the heat medium supply line (36) into a communication state or a communication blocking state with the heat medium passage (30) or the heat medium circulation line (54);
the cooling thermostat (38) controls the temperature of the cooling medium;
the refrigerant supply line (40) supplies the cooling medium from the cooling thermostat (38) to the refrigerant passage (32);
the control unit (44) is configured to switch from a state in which the heating medium flows through the heat medium passage (30) to a state in which the cooling medium flows through the cooling medium passage (32), and to switch from a state in which the cooling medium flows through the cooling medium passage (32) to a state in which the heating medium flows through the heat medium passage (30);
the discharge fluid supply source (66) supplies a discharge fluid for discharging the cooling medium in the refrigerant passage (32),
the controller (44) supplies the heating medium to the heat medium passage (30) in a state in which the inside of the cooling medium passage (32) is replaced with the discharge fluid, thereby heating the mold (14).
6. The injection molding apparatus (10) of claim 5,
the controller (44) supplies the discharge fluid when switching from a state in which the cooling medium flows through the cooling medium passage (32) to a state in which the heating medium flows through the heating medium passage (30).
7. The injection molding apparatus (10) of claim 5 or 6,
further comprising a refrigerant circulation line (62) and a 2 nd switching valve (60), wherein the refrigerant circulation line (62) branches off from the refrigerant supply line (40) and returns the cooling medium to the cooling thermostat (38); the 2 nd switching valve (60) selectively brings the refrigerant supply line (40) into a communication state or a communication blocking state with the refrigerant passage (32) or the refrigerant circulation line (62).
8. The injection molding apparatus (10) of claim 7,
when the heating medium flows through the heat medium passage (30), the cooling medium is returned from the refrigerant supply line (40) to the cooling thermostat (38) through the refrigerant circulation line (62).
9. The injection molding apparatus (10) of claim 7,
when the cooling medium in the refrigerant passage (32) is discharged using the discharge fluid, the cooling medium is caused to flow from the refrigerant supply line (40) through the refrigerant circulation line (62) and return to the cooling thermostat (38).
10. The injection molding apparatus (10) of claim 5,
oil is supplied as the heating medium, and water is supplied as the cooling medium.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2017014547 | 2017-01-30 | ||
| JP2017-014547 | 2017-01-30 | ||
| PCT/JP2018/002881 WO2018139664A1 (en) | 2017-01-30 | 2018-01-30 | Injection moulding method and injection moulding device |
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| Publication Number | Publication Date |
|---|---|
| CN110234489A CN110234489A (en) | 2019-09-13 |
| CN110234489B true CN110234489B (en) | 2021-11-19 |
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| CN201880008936.5A Active CN110234489B (en) | 2017-01-30 | 2018-01-30 | Injection molding method and injection molding apparatus |
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| JP (1) | JP6820950B2 (en) |
| CN (1) | CN110234489B (en) |
| WO (1) | WO2018139664A1 (en) |
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| KR20210039653A (en) * | 2019-10-02 | 2021-04-12 | 삼성전자주식회사 | Apparatus for controlling temperature of metal mold |
| CN114074452B (en) * | 2020-08-21 | 2024-03-19 | 汉达精密电子(昆山)有限公司 | Vapor compressed gas combined quenching and rapid heating system and method |
| CN114506005B (en) * | 2022-02-21 | 2024-04-16 | 浙江金凤凰电力科技股份有限公司 | Injection vulcanization system for producing silicone rubber umbrella cover |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002301750A (en) * | 2001-04-03 | 2002-10-15 | Mitsubishi Materials Corp | Mold apparatus and controlling method of temperature thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS536360A (en) * | 1976-07-07 | 1978-01-20 | Toyo Machinery & Metal | Method of heating and cooling mold for injection molding |
| JPH01291906A (en) * | 1988-05-20 | 1989-11-24 | Hitachi Ltd | Mold temperature adjustment device |
| JP3281420B2 (en) * | 1992-01-31 | 2002-05-13 | 橋本フォーミング工業株式会社 | Method and apparatus for manufacturing resin molded product |
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2018
- 2018-01-30 WO PCT/JP2018/002881 patent/WO2018139664A1/en active Application Filing
- 2018-01-30 CN CN201880008936.5A patent/CN110234489B/en active Active
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002301750A (en) * | 2001-04-03 | 2002-10-15 | Mitsubishi Materials Corp | Mold apparatus and controlling method of temperature thereof |
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| Publication number | Publication date |
|---|---|
| JPWO2018139664A1 (en) | 2019-11-07 |
| WO2018139664A1 (en) | 2018-08-02 |
| JP6820950B2 (en) | 2021-01-27 |
| CN110234489A (en) | 2019-09-13 |
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