JP2006142781A - Mold and method for injection press molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent leakage of a molding material from a cavity when injection and press are carried out in the state of partial opening, and also leakage from a gap between a runner plate and a fixed mold in the case of a mold having a three-side opening structure by a simple structure. <P>SOLUTION: A mold for injection press molding includes the fixed mold 2; a core 3 mold-clamped with the fixed mold, a seal block 4 placed around the mold face of the core, movable in a mold switching direction, and mold-clamped with the parting face of the fixed mold and the core; and a cylinder device 5 driving in a direction of approaching the seal block to the core and being apart from the core. Since the cylinder device 5 may be configured so as to allow the seal block 4 to be pressed with a larger force than an injection pressure, it is not necessary to output a larger force than a mold-clamping force and the cylinder device can be miniaturized. Further, since the mold has a structure so as to generate a press force by the mold-clamping force, a proper press force can easily be generated even if the projected area of the cavity is large. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is an injection press in which a mold is slightly opened before injection of a molding material, the mold is stopped (fixed) in a state where the cavity is expanded, the molding material is injected into the cavity, and then the mold is clamped (pressed). The present invention relates to a mold used for a molding method and an injection press molding method using the mold.

  With the recent reduction in weight of vehicles, the fuel tank is also being studied for resin. Since the fuel tank is in the shape of a container, it is preferable to manufacture it by blow molding, but it is often a relatively complicated shape to provide an evaporation circuit or a flow control plate, and it is difficult to manufacture by blow molding. There are many. Therefore, use of injection molding can be considered. In other words, if a pair of halved members divided at the top and bottom of the fuel tank are respectively molded and welded together, even a complicated shape can be easily manufactured.

  However, in order to promote weight reduction, it is necessary to reduce the wall thickness, and it is necessary to narrow the gap between the cavities. In addition, since a molded product having a large projected area is molded, it is difficult to fill the entire cavity with a molding material in injection molding, resulting in a lack of thickness. Therefore, the use of injection press molding is considered as seen in, for example, JP-A-2004-098886.

  In the injection press molding, first, the molding material is injected in a state where the gap between the cavities is slightly widened, and then the molding material is press-molded by clamping to fill the entire cavity with the pressing pressure. Therefore, even if the space between the cavities is narrow, the molding material can be easily filled into the cavities. Moreover, since the restrictions on the shape of the mold surface are small, it is suitable for manufacturing a fuel tank.

  However, in the injection press molding, there is a case where the molding material leaks due to the injection pressure or the pressing pressure from the open cavity when the molding material is injected or pressed. Various solutions have been made to solve this problem, and Japanese Patent Laid-Open No. 07-032424 discloses that a seal block that is pressed against a fixed parting surface is arranged around a movable mold surface and is opened at the time of opening. A technique for preventing resin leakage due to injection pressure by bringing a seal block into pressure contact with a fixed parting surface by a biasing force of a spring is disclosed. However, this technique requires a locking rod for fixing the seal block in a state where it is in pressure contact with the fixed parting surface at the time of opening, and there is a problem that the number of parts is large. Moreover, the operation | movement of latching rod cancellation | release is required and a shaping | molding cycle becomes long.

  Japanese Patent Laid-Open No. 06-106590 discloses that a fixed block is provided with a PL block that can be moved back and forth in a movable mold, and the PL block presses against the movable taper surface when opening, thereby preventing leakage of molding material. Techniques for preventing are disclosed. However, with this technology, the PL block is pressed against the movable taper surface using the biasing force of the coil spring, so it is necessary to prevent the PL block from moving due to the injection pressure, and a large biasing force is generated. A spring is required. Furthermore, since the urging force of the spring becomes a resistance during mold clamping, it is necessary to further increase the mold clamping force, and there is a problem that the apparatus tends to be large.

  Furthermore, in the case of a mold with a three-sided opening structure having a multi-point gate, it is necessary to hold the runner plate and the fixed mold in pressure contact when injecting in the fully open state. Can not.

  Therefore, a mold structure as shown in FIG. 7 is adopted. This mold structure is a three-sided opening structure composed of a runner plate 100, a fixed mold 200, and a movable mold 300. The runner plate 100 and the fixed mold 200 can be pressed and fixed by a clamp mechanism 101. Therefore, even if the fixed mold 200 and the movable mold 300 are in the open state, the runner plate 100 and the fixed mold 200 can be kept in the pressure contact state, so that the molding material leaks from between the runner plate 100 and the fixed mold 200 due to the injection pressure. There is no. Further, when the mold is opened, the runner portion can be released by releasing the clamp by the clamp mechanism 101.

  A core back structure as shown in FIG. 8 is also employed. In this mold structure, since the cylinder device 400 lowers only the core 301 of the movable mold 300 to bring it into an open state, the portion around the core 301 is pressed against the fixed mold 200 by the clamping force, and the fixed mold 200 is The runner plate 100 is pressed. Therefore, the runner plate 100 and the fixed mold 200 can be kept in the pressure contact state in the dimensionally opened state, and the molding material does not leak from between the runner plate 100 and the fixed mold 200 due to the injection pressure. At the time of pressing, the cylinder device 400 presses and raises the core 301 to fill the cavity with the molding material.

However, in the former mold structure, the clamp mechanism 101 is required, which is difficult in terms of cost and molding cycle. In the latter mold structure, it is necessary to cause the cylinder device 400 to generate a pressing force equivalent to the clamping force required for the molding machine at the time of pressing, and the cylinder device 400 is large, and there are restrictions in terms of space and cost. large.
JP 07-032424 JP 06-106590 JP2004-098886

  The present invention has been made in view of the above circumstances, has a simple structure, prevents leakage of the molding material from the cavity at the time of injection in the open state, and at the time of pressing, and is a mold having a three-sided open structure. In this case, it is an issue to be solved to prevent leakage from between the runner plate and the fixed mold.

  The features of the injection press molding mold of the present invention that solves the above problems are a fixed mold, a movable mold that is clamped to the fixed mold, a cavity that is formed between the fixed mold and the movable mold, and a movable mold Is placed around the mold surface and movable in the mold opening and closing direction, the fixed mold parting surface, the seal block to be clamped with the movable mold, and the seal block is driven in the direction close to the movable mold and away from the movable mold And a mold clamping device that clamps the movable mold and the seal block.

  The injection press molding method of the present invention is characterized in that the injection press molding die of the present invention is used, the movable mold is retracted to make the cavity open, and the seal block is fixed by the cylinder device. An injection process that regulates leakage of molding material from the cavity by the seal block by injecting the molding material into the cavity with a pressure larger than the injection pressure, and the movable mold and the seal block are fixed by moving the movable mold forward And a molding step of press-molding the molding material by clamping the mold.

  Note that a mold having a three-sided opening structure that further includes a runner plate that is clamped to the fixed mold on the side opposite to the movable mold of the fixed mold. When this mold is used, the movable mold is retracted to open the cavity, and the cylinder block is used to press the seal block against the fixed parting surface with a force larger than the injection pressure, and the fixed mold is runner-up. An injection process that regulates leakage of the molding material from between the runner plate and the fixed mold and regulates leakage of the molding material from the cavity by the seal block by injecting the molding material into the cavity while being pressed against the plate; Then, the molding step of press-molding the molding material is performed by moving the movable die forward and clamping the movable die and the seal block with the fixed die.

  According to the injection press molding die of the present invention, the cylinder device only needs to be configured to be able to press the seal block with a force larger than the injection pressure, so there is no need to output a force larger than the clamping force. Miniaturization or number reduction is possible. Further, since a locking rod, a clamp mechanism, and the like are not required, it is advantageous in terms of space and cost. Furthermore, since the pressing force is generated by the mold clamping force, an appropriate pressing force can be easily generated even when the projected area of the cavity is large.

  According to the injection press molding method of the present invention, since the generation of burrs is prevented, a post-treatment process becomes unnecessary, and the number of man-hours can be greatly reduced.

  In the injection press molding method using the injection press molding die of the present invention, in the injection step, the movable mold is retracted to open the cavity, and the cylinder block is used to place the seal block on the fixed parting surface. Pressing with a force larger than the injection pressure, and in that state, the molding material is injected into the cavity in the open state. Therefore, the periphery of the movable mold surface is sealed by the seal block being pressed against the fixed parting surface, so that leakage of the molding material from the cavity is reliably regulated.

  In the molding process, the movable mold is moved forward to clamp the movable mold, the seal block, and the fixed mold, and the cavity in the open state becomes a normal dimension, and the molding material is applied to every corner of the cavity by the mold clamping force. Filled and press-molded.

  The cylinder device can be provided outside the movable type, but is preferably provided integrally with the movable type from the viewpoint of space. However, when it is provided integrally with the movable die, a large force in the reverse direction from the movable die acts on the cylinder device that presses the seal block in the molding process, and the cylinder device may be damaged. Therefore, it is desirable to reduce the force that presses the seal block in synchronization with the movable advance. For example, in the case of a hydraulic cylinder device, it may be driven in the direction opposite to the pressing, the hydraulic pressure is temporarily reduced, or the oil is temporarily removed. Thereby, damage to the cylinder device can be prevented. It should be noted that the timing for reducing the pressing force of the cylinder device is desirably performed immediately after the movable mold comes into contact with the seal block. As a result, the pressure contact state between the seal block and the fixed mold can be maintained, so that leakage of the molding material from the cavity in the molding process can be reliably prevented.

  In the case of a mold having a three-sided opening structure, it is necessary to regulate leakage of the molding material from between the runner plate and the fixed mold. The injection press molding die of the present invention is also useful in that case. That is, according to the mold of the present invention, the runner plate, the fixed mold, the seal block, and the movable mold are laminated in this order, and the moving direction of the movable mold and the driving direction of the cylinder device can be easily made parallel. Accordingly, when the movable mold is retracted to open the cavity, and the cylinder device presses the seal block against the fixed parting surface with a force larger than the injection pressure, the pressing force of the cylinder device and the seal block If it is transmitted to the runner plate via the fixed mold, the fixed mold can be easily pressed against the runner plate. Thereby, in the injection process, it is possible to prevent the molding material from leaking from the cavity and to surely prevent the molding material from leaking between the runner plate and the fixed mold.

  As the cylinder device, one driven by hydraulic pressure or gas pressure can be used. Moreover, you may use together the urging | biasing force of springs, such as a spring.

  Hereinafter, the present invention will be described specifically by way of examples.

Example 1
FIG. 1 shows a cross-sectional view of the injection press molding die of this embodiment in a clamped state. This mold is for molding a half-shaped molded product of a resin fuel tank. The runner plate 1 is pressed against the fixed die plate 10; the fixed die 2 is pressed against the runner plate 1; And a ring-shaped seal block 4 formed around the movable mold 3 and in contact with the parting surface of the fixed mold 2.

  A nozzle touch 11 is formed on the fixed die plate 10, and a sprue portion 12 communicating with the nozzle touch 11 is opened on the surface of the runner plate 1 facing the fixed mold 2. A runner cavity 13 is formed between the surface of the runner plate 1 where the sprue portion 12 opens and the fixed mold 2 facing the runner plate 1. The fixed mold 2 is configured to be able to contact and separate from the runner plate 1, and a spring 14 is interposed between the two. The spring 14 is arranged so that the urging force in a direction in which the runner plate 1 and the fixed mold 2 are pressed against each other is stored. The fixed mold 2 is formed with a plurality of gates 20 that communicate with the runner cavity 13 and open on the opposite surface, and a fixed mold surface 21 and a parting surface 22 are formed on the surface side where the gate 20 opens. Yes.

  The movable mold 3 is fixed to the movable die plate 30 via the back plate 31. A movable mold surface 32 is formed on the surface of the movable mold 3, and a thin plate-like cavity 23 is formed between the fixed mold surface 21 and the movable mold surface 32. The cavity 23 is bent at a substantially right angle at the peripheral edge of the movable mold 3 so that a container-like molded product can be formed as a whole.

  A ring-shaped seal block 4 is provided around the movable mold 3 so as to be in sliding contact with the core 3 in the mold clamping / mold opening direction. The seal block 4 is formed so as to be able to press contact with the parting surface 22 of the fixed mold 2, and a part of the surface forms a mold surface that is continuous with the fixed mold surface 21 of the fixed mold 2. A hydraulic cylinder 5 is built in and fixed to the mounting plate 30, and the tip of the piston rod 50 of the hydraulic cylinder 5 is engaged with the seal block 4, and the seal block 4 is moved in the mold clamping and mold opening direction by the hydraulic cylinder 5. It is possible. A spring 40 is interposed between the mounting plate 30 and the seal block 4 to urge the seal block 4 in a direction away from the mounting plate 30.

  In the injection press molding die of the present embodiment configured as described above, the fixed die plate 10 is fixed to the injection plunger side of the molding machine with the injection nozzle in contact with the nozzle touch 11. On the other hand, the movable die plate 30 is fixed to the drive side of the molding machine. Then, as shown in FIG. 2, first, the hydraulic cylinder 5 is driven forward with the movable mold 3 slightly retracted from the mold-clamping state, and the seal block 4 is moved together with the urging force of the spring 40. Press contact with surface 22.

  In this state, molten resin is supplied from the injection plunger. The molten resin passes through the sprue portion 12, fills the runner cavity 13, and is then injected from the plurality of gates 20 into the cavity 23 in the open state. At this time, the seal block 4 is pressed against the parting surface 22 of the fixed mold 2 by the pressure of the hydraulic cylinder 5 and the spring 40, and since the force is larger than the injection pressure of the molten resin, it is certain that the molten resin leaks from the cavity 23. To be prevented. Further, since the runner plate 1 and the fixed mold 2 are pressed against each other with a force larger than the injection pressure by the pressing force of the hydraulic cylinder 5 and the spring 40, the molten resin is surely prevented from leaking from the runner 13.

  After injecting a predetermined amount of molten resin, the clamping force of a molding machine (not shown) is transmitted to the movable die plate 30 and moves forward until the back plate 31 comes into contact with the seal block 4 as shown in FIG. Move forward and mold clamping. At this time, by simultaneously pulling in and driving the hydraulic cylinder 5 or simultaneously canceling the thrust, the load on the hydraulic cylinder 5 due to the application of the clamping force is reduced and the mold product is prepared for demolding. Further, since the clamping force from the mounting plate 31 is transmitted to the seal block 4 in place of the pressing force of the hydraulic cylinder 5, the pressing pressure acts uniformly and reliably on the molten resin in the cavity 23.

  After the mold clamping is continued until the cooling of the molded product is completed, the mold clamping force is released and the mold opening is performed. At this time, as shown in FIG. 4, the fixed mold 2 is separated from the runner plate 1 by the urging force of the spring 14, so that the gate 60 is separated from the runner 61, and the runner 61 and the sprue 62 remain on the runner plate 1. The hydraulic cylinder 5 is driven in a direction in which the seal block 4 is pressed against the mounting plate 31, and the fixed mold 2 and the movable mold 3 are separated. Therefore, the gate 60 is released from the fixed mold 2 together with the molded product 6, and the molded product 6 to which the gate 60 is adhered remains in the movable mold 3, so that it is removed from the movable mold 3, and the gate 60 is cut off to form the molded product. 6 is obtained.

  Therefore, the molded product 6 obtained by the injection press molding method of the present embodiment does not have burrs, so that post-processing such as trimming is not necessary. Further, since the hydraulic cylinder 5 may be configured to be able to press the seal block 4 with a force larger than the injection pressure, it is not necessary to output a force larger than the clamping force, and a small or a small number of hydraulic cylinders 5 can be used. Further, since a locking rod, a clamp mechanism, and the like are unnecessary, the mold of this embodiment is advantageous in terms of space and cost. Furthermore, since the pressing force is generated by the mold clamping force, an appropriate pressing force can be easily generated even when the projected area of the cavity is large.

  The movable mold 3 and the back plate 31 may be integrated.

(Example 2)
The mold of this embodiment shown in FIGS. 5 and 6 has a double-sided structure with a single-point gate, and is the same as that of Embodiment 1 except that it does not have a runner plate.

  With the injection nozzle in contact with the nozzle touch 11, the fixed die plate 10 is fixed to the injection plunger side of the molding machine. On the other hand, the movable die plate 30 is fixed to the drive side of the molding machine. Then, as shown in FIG. 5, first, the hydraulic cylinder 5 is driven with the movable mold 3 slightly retracted from the mold-clamping state, and the sealing block 4 is moved together with the urging force of the spring 40 to the parting surface of the fixed mold 2. Press contact with 22.

  In this state, molten resin is supplied from the injection plunger. Molten resin is injected from the gate into the cavity 23 in an open state. At this time, the seal block 4 is pressed against the parting surface 22 of the fixed mold 2 by the pressure of the hydraulic cylinder 5 and the spring 40, and since the force is larger than the injection pressure of the molten resin, it is certain that the molten resin leaks from the cavity 23. Has been prevented.

  After injecting a predetermined amount of molten resin, the clamping force of a molding machine (not shown) is transmitted to the movable die plate 30 and moves forward until the mounting plate 31 comes into contact with the seal block 4 as shown in FIG. Move forward and mold clamping. At this time, by simultaneously pulling in and driving the hydraulic cylinder 5 or simultaneously canceling the thrust, the load on the hydraulic cylinder 5 due to the application of the clamping force is reduced and the mold product is prepared for demolding. Further, since the clamping force from the mounting plate 31 is transmitted to the seal block 4 in place of the pressing force of the hydraulic cylinder 5, the pressing pressure acts uniformly and reliably on the molten resin in the cavity 23.

  After the mold clamping is continued until the cooling of the molded product is completed, the mold clamping force is released and the mold opening is performed. At this time, the hydraulic cylinder 5 is driven in a direction in which the seal block 4 is pressed against the mounting plate 31, and the fixed mold 2 and the movable mold 3 are separated. Accordingly, the sprue is released from the fixed mold 2 together with the molded product, and the molded product to which the sprue is attached remains in the movable mold 3, so that the molded product is obtained by removing it from the movable mold 3 and cutting the sprue.

  Therefore, the molded product obtained by the injection press molding method of the present embodiment does not have burrs, so that post-processing such as trimming is not necessary. Further, since the hydraulic cylinder 5 may be configured to be able to press the seal block 4 with a force larger than the injection pressure, it is not necessary to output a force larger than the mold clamping force, and a small or small number of hydraulic cylinders 5 can be used. Further, since a locking rod, a clamp mechanism, and the like are unnecessary, the mold of this embodiment is advantageous in terms of space and cost. Furthermore, since the pressing force is generated by the mold clamping force, an appropriate pressing force can be easily generated even when the projected area of the cavity is large.

  The injection press molding die of the present invention is most suitable for producing a molded product having a large projected area such as a fuel tank of an automobile.

It is sectional drawing in the clamping state of the metal mold | die for injection press molding of one Example of this invention. It is sectional drawing which shows the state which is performing the injection process by opening the mold for injection press molding of one Example of this invention. It is sectional drawing shown in the state which is performing the shaping | molding process using the metal mold | die for injection press molding of one Example of this invention. It is sectional drawing shown in the state which is performing the demolding process using the injection die for injection molding of one Example of this invention. It is sectional drawing which shows the state which has opened the injection press molding die of the 2nd Example of this invention, and opens the injection process. It is sectional drawing shown in the state which is performing the shaping | molding process using the metal mold | die for injection press molding of 2nd Example of this invention. It is sectional drawing which shows the conventional injection press molding die in the state which has performed the injection process and the shaping | molding process. It is sectional drawing which shows the conventional injection press molding die in the state which has performed the injection process and the shaping | molding process.

Explanation of symbols

1: Runner plate 2: Fixed type 3: Movable type 4: Seal block 5: Hydraulic cylinder 6: Molded product
13: Runner cavity 22: Parting surface 23: Cavity
31: Back plate 40: Spring

Claims (5)

  A fixed mold, a movable mold clamped to the fixed mold, a cavity formed between the fixed mold and the movable mold, and arranged around the mold surface of the movable mold and movable in the mold opening / closing direction. The fixed mold parting surface and the seal block to be clamped to the movable mold, the cylinder device for driving the seal block in the direction close to the movable mold and in the direction away from the movable mold, the movable mold and A mold for injection press molding comprising: a mold clamping device for clamping the seal block with the fixed mold.   The injection press molding die according to claim 1, further comprising a runner plate clamped to the fixed die on the opposite side of the fixed die to the movable die. The injection press molding die according to claim 1 is used, the movable die is retracted to make the cavity open, and the cylinder block is used to place the seal block on the parting surface of the fixed die by injection pressure. An injection step of restricting leakage of the molding material from the cavity by the seal block by injecting the molding material into the cavity in a state of being pressed with a large force;
An injection press molding method comprising: a molding step of press molding the molding material by advancing the movable mold by the mold clamping device and clamping the movable mold and the seal block with the fixed mold. . 3. The injection press molding die according to claim 2, wherein the movable die is retracted to bring the cavity into an open state, and the cylinder block is used to place the seal block on the parting surface of the fixed die by injection pressure. The molding material is injected into the cavity while being pressed with a large force and the fixed mold is pressed against the runner plate, thereby restricting the leakage of the molding material from between the runner plate and the fixed mold. An injection process for regulating leakage of the molding material from the cavity by the seal block;
An injection press molding method comprising: a molding step of press molding the molding material by advancing the movable mold by the mold clamping device and clamping the movable mold and the seal block with the fixed mold. .   5. The injection press molding method according to claim 3, wherein the cylinder device is fixed to the movable mold and reduces a force pressing the seal block simultaneously with the advance of the movable mold in the molding step.

Images