TWI503219B - A thin plate injection molding method and a thin plate injection press forming apparatus - Google Patents

Description

Injection molding method for sheet and injection molding apparatus for sheet

The present invention relates to an injection press forming method for a thin plate and an injection press forming device for a sheet.

The formation of a resin-made thin plate typified by a light guide plate is often carried out by injection press molding which is an injection compression molding. In the injection press molding, the movable disk is stopped at an approaching position, and a compressible cavity is formed between the fixed mold and the movable mold, and the molten resin injected toward the cavity is compressed and molded. Therefore, injection molding is a method of forming a sheet suitable for forming a light guide plate or the like in a state where the cavity is enlarged in the molding die.

There are two methods for stopping the movable mold at the approaching position in the injection press molding. The first method is a method of moving the movable mold from the mold opening position to stop it in the imminent position. The second method is a method in which the movable mold is once moved to the opening direction and then stopped at the imminent position after the mold is abutted. In the former method, since the step of moving the movable mold once to the mold abutting position and then opening is not present, there is an advantage that the molding cycle can be shortened, and the disk forming or the like is employed. However, in the former method, the movable mold reaches the target position at a high speed and is stopped in a state where the molds are not in contact with each other, and thus there is a problem with respect to the stop accuracy at the approach position. In the latter method, although the time to reach the approaching position becomes long, the stopping accuracy at the approaching position is excellent.

However, in the case of the entire injection molding including injection molding, the members of the fixed disk, the movable plate, the tie bar, the bed, and the like are heated around the molding die as the forming cycle is repeated from the start of molding. Thermal expansion occurs to affect the formation. In order to solve the problem of thermal expansion of a molding die or the like as described above, the techniques described in Patent Document 1 and Patent Document 2 are known.

According to the technique described in Patent Document 1, after the mold clamping is confirmed, the mold thickness is corrected based on the position of the movable mold detected by the mold position detecting means. However, Patent Document 1 does not relate to injection pressure but to a technique of general injection molding. Therefore, as described in paragraph 0037, the sampling of the mold position data for correcting the thickness of the mold is performed in a state in which the large pressing force is applied after the mold clamping is completed. Further, Patent Document 1 does not disclose how to move the movable disk or the like to the approaching position in the injection press molding, and therefore it is not suitable for injection press molding. Further, in the technique described in Patent Document 2, the thickness of the mold is corrected in the injection press molding. However, the method is such that the movable mold is moved from the mold opening position to stop at the approaching position, and the following problems occur.

[Patent Document 1] Japanese Patent Laid-Open No. 7-148740 (Request No. 1, 0037, 3)

[Patent Document 2] Japanese Laid-Open Patent Publication No. 2009-208412 (Request No. 1, Fig. 1, Fig. 2)

That is, in Patent Document 2, the movable mold arrives at a higher speed as described above. The target position (immediate position) is stopped in a state where the molds are not in contact with each other, and as described above, there is a problem in the stop accuracy of the approaching position. The measured position is used for correction although it is stored, but it is not reflected in the measurement molding cycle, but is used in the next molding cycle. Therefore, in each molding cycle, the measured molding position cannot be reflected, and the precision of the molded article is lowered.

Accordingly, an object of the present invention is to provide an injection molding method for a thin plate and an injection press molding device for a thin plate, which can stop the movable mold at a correct approach position even when the molding die or the like is affected by thermal expansion. Good injection molding is performed.

The injection pressure forming method for a thin plate according to claim 1 of the present invention is to stop the movable disk at an imminent position, and the approaching position is to form a compressible cavity between the fixed mold and the movable mold, toward the aforementioned cavity. The molten resin that is ejected is compressed by advancing the movable disk, and is characterized in that The positioning control of the movable disk toward the approaching position is performed by moving the movable disk toward the mold closing direction, and stopping the movable disk at the offset position at which the clamping force is set below the maximum clamping force. After correcting the control origin, the component of the set value is moved from the offset position toward the mold opening direction.

The mold clamping device according to claim 2 of the present invention is the offset position detected by the set mold clamping force of the maximum mold clamping force in the request item 1, each molding cycle or each plural molding cycle. Correct the control origin once.

The injection press forming apparatus for a thin plate according to claim 3 of the present invention stops the movable disk at an approaching position, and the approaching position is in a fixed mold. Forming a compressible cavity between the movable mold and the molten resin ejected toward the cavity, and allowing the movable disk to advance and compress, wherein The positioning control of the movable disk toward the approaching position is performed by moving the movable disk toward the mold closing direction, and stopping the movable disk at the offset position at which the clamping force is set below the maximum clamping force. After correcting the control origin, the component of the set value is moved from the offset position toward the mold opening direction.

The mold clamping device according to claim 4 of the present invention is characterized in that, in the request item 3, a position sensor is provided for detecting between the pressure plate and the movable plate, the base and the movable plate Between the fixed disc and the movable disc, the position sensor detects the movable disc located at the offset position at which the set clamping force is detected below the maximum clamping force. Correct the control origin.

The injection pressure forming method and the injection pressure forming device of the thin plate of the present invention stop the movable disk at an approaching position which forms a compressible cavity between the fixed mold and the movable mold, toward the aforementioned cavity The molten resin is ejected, and the movable disk is advanced to be compressed. The positioning control of the movable disk toward the approaching position is performed by moving the movable disk in the mold closing direction and clamping the setting below the maximum clamping force. When the offset position of the force is detected, the movable disk is stopped and the control origin is corrected, and the component of the set value is moved from the offset position toward the mold opening direction. Therefore, the movable mold can be stopped at the correct approach position in each molding cycle.

An outline of the injection press forming apparatus 11 of the embodiment of the present invention Slightly, it will be explained with reference to Fig. 1. The basic portion of the injection press molding device 11 is composed of a mold clamping device 13 provided on one side of the susceptor 12 and an injection device 14 disposed on the other side. The injection device 14 is a known material, and the resin material is plasticized by a screw provided in the heating cylinder, and the plasticized molten resin is ejected from the nozzle. A cylinder mechanism or a motor-driven mechanism as the nozzle contact mechanism 16 is attached to both sides of the nozzle hole 15a formed at the center of the surface on the opposite side of the movable disk of the fixed disk 15. A pre-molding injection device or the like can also be used for the injection device.

For the mold clamping device 13, a fixed disk 15 for mounting the fixed mold 19 is disposed on the susceptor 12. Further, a pressure receiving disk 18 is disposed on the base 12 on one side of the fixed disk 15 (opposite side of the injection device). The vicinity of the four corners of the fixed disk 15 and the pressure plate 18 are connected by a tie bar 20, and the tie bar 20 is fixed by a nut 36. Further, between the fixed disk 15 and the pressure receiving disk 18, a movable disk 21 for attaching the movable mold 22 to the mold opening and closing direction is provided. The materials of the four tie bars 20 and the manner in which they are fixed toward the fixed disk 15 and the pressure plate 18 are well known. The injection press molding apparatus 11 can also be used for injection compression molding (injection from a closed mold state) and general injection molding.

Next, the mounting of the fixed disk 15 and the fixed disk 15 toward the susceptor 12 will be described. On the outside of both side faces of the fixed disk 15, the guide member 23 is fixed to the base 12 by bolts 28 having claw-shaped projections facing inward and in the horizontal direction. Further, the protruding portion of the guiding member 23 is inserted into the concave portion on the side surface of the fixed disk 15. The fixing plate 15 is not fixed to the base 12 by bolts or the like, but is guided by the guiding member 23 to open and close the mold. The movement of the direction is not limited. Therefore, although the name of the fixed disk 15 is used here, it is strictly for mounting the fixed mold 19 but forming a non-fixed disk with respect to the base 12.

Next, the pressure receiving disk 18 and the mold clamping cylinder 37 will be described. The pressure receiving plate 18 is a disk for placing the mold clamping cylinder 37 as a mold clamping mechanism on the base 12, and the cylinder portion 38 of the mold clamping cylinder 37 is fixed at the center portion thereof (in the present embodiment, the pressure plate) 18 is also part of the clamping cylinder 37). Although not shown in the drawings, the cylinder barrel of the cylinder portion 38 is provided with an auxiliary plunger cylinder as a mold closing mechanism for advancing the punching rod 39 at a high speed, and a large-sized supercharging cylinder as a mold opening mechanism and a mold clamping mechanism. A piston; a punch 39 fixed to the piston is fixed to a central portion of the back surface 21b of the movable disk 21. Therefore, in the mold clamping mechanism of the present embodiment, the fixed mold 19 and the movable mold 22 are clamped by directly applying pressure to the central portion of the movable disk 21, and the toggle portion of the link is mounted near the outer side of the movable plate. The mold clamping device can reduce the deflection of the movable disk 21 due to the mold clamping force. Although the hydraulic mechanism of the mold clamping cylinder 37 is not described, it is preferable to use a servo valve for high-precision control. Further, the mold clamping device of the present invention does not exclude other mold clamping mechanisms using the above-described toggle clamping device and the clamping cylinder of the split nut.

Next, the mounting of the pressure receiving disk 18 toward the susceptor 12 will be described. On both sides of the lower portion of the pressure receiving disk 18, the mounting portion 29 is protruded in a direction orthogonal to the opening and closing direction of the mold. Further, a through hole in the vertical direction is formed in the mounting portion 29. The ram 12 is inserted from the upper side of the through hole toward the lower side to insert the shoulder bolt 32, whereby the pressure receiving disk 18 is attached to the susceptor 12. Further, the central portion of the lower surface of the pressure plate 18 is attached to the base 12 via a spherical bearing 34. The spherical bearing 34 is used as a A shaft support portion for supporting the pressure receiving disk 18. Therefore, although the pressure receiving disk 18 cannot move in the mold opening and closing direction with respect to the susceptor 12, the angle of the disk can be slightly changed centering on the center of the spherical bearing 34. Further, the boss portion under the pressure receiving disk 18 can be inserted into the hole on the side of the susceptor 12, whereby the pressure receiving disk 18 can be moved in the mold opening and closing direction with respect to the susceptor 12, but the angle can be slightly changed. Further, the cylinder portion 38 of the mold clamping cylinder 37 is an angle adjusting mechanism 40 having a constant length toward the opposite side of the fixed disk and a pressure receiving disk 18 attached to the rear end thereof. Further, by the angle adjusting mechanism 40, the angle of the pressure receiving disk 18 can be changed in each direction.

Next, the movable disk 21 will be described. The movable platen 21 is a disk body having a constant thickness, the front surface of which is the mounting surface 21a of the movable mold 22, and the punching head 39 is fixed to the back surface 21b. As shown in Fig. 1, between the fixed disk 15 and the pressure receiving disk 18 on the susceptor 12, linearly arranged one by one in parallel with the axis X of the die opening and closing direction at a position outside the side surface of the fixed disk 15 Guide rail 58 of guide mechanism 57. On the other hand, the housing 60 of the linear guide mechanism 57 is fixed to the leg portions 59 on both sides of the lower surface of the movable disk 21. Further, the leg portions 59 of the movable platen 21 are respectively protruded toward the fixed disk side and the pressure receiving disk side, and the housing 60 is attached to the fixed disk side and the pressure receiving disk side of the leg portion 59, respectively. The mounting of the casing 60 with respect to the leg portion 59 of the movable platen 21 is performed by an eccentric shaft that is disposed in a horizontal direction orthogonal to the mold opening and closing direction (not shown). Therefore, by fixing the eccentric shaft and fixing it, the vertical height of the casing 60 can be changed with respect to the movable platen 21, and the height of the movable platen 21 can be adjusted.

Further, a through hole 56 for inserting the tie bar 20 is formed in the vicinity of the four corners of the movable plate 21. In the present embodiment, the through hole of the movable plate 21 The hole 56 is not inserted into the bushing, and the movable platen 21 is disposed so as not to directly apply a load to the tie bar 20 in a non-contact state even when the mold is closed. In other words, the movable disk 21 is vertically erected on the susceptor 12 by the linear guide mechanism 57, and is guided by the linear guide mechanism 57 to move. Further, the movable disk can also be used in a known form in which the tie bar is inserted through the guide bushing, or the tie bar is not inserted.

In the present embodiment, a position sensor 42 for detecting the position (the distance between the pressure receiving disk 18 and the movable disk 21) for detecting the movable disk 21 is provided between the pressure receiving disk 18 and the movable disk 21. The position sensor 42 is for detecting the movement of the movable disk 21 between the mold opening completion position A and the mold clamping position G in Fig. 2 . The position of the position sensor 42 is preferably a member (a part of the susceptor 12) provided on the susceptor 12 on the side of the pressure plate 18, except for the space between the pressure plate 18 and the movable plate 21 as described above. ) and the movable plate 21. In the present embodiment, the position sensor 42 uses a linear ruler, but other position sensors such as a rotary encoder or a potentiometer can also be used. Further, the cylinder switching position C, the mold protection start position B, and the like which will be described later may be set using a limit switch.

The mold clamping device 13 is fixed to the susceptor 12 and the fixed disk 15 is movable as in the present embodiment, and the position sensor 42 is disposed between the pressure plate 18 and the movable disk 21 (or the movable mold 22). In that, since the sensor is not mounted on the fixed disk 15, even if the fixed disk 15 is deformed by tilting, flexing, or the like, it is not affected. Further, the fixed disk 15 (or the pedestal 12 located on the side thereof) and the movable disk 21 serve as a space for mold replacement and removal of the molded article, and the position sensor 42 does not interfere with these operations. But its shortcomings Therefore, since the distance between the fixed disk 15 and the movable disk 21 cannot be directly detected, it is easily affected by the extension of the tie bar 20, and even at the approach position F shown in FIGS. 2 and 5 (the movable mold before the start of the injection) When the standby position of 22 is started, the injection filling is started, and the movable disk 21 is moved backward toward the pressure receiving disk 18 by the injection pressure. When the fixed disk 15 is also moved backward toward the injection device 14, the position sensor 42 is difficult to grasp the movable disk. The state of 21.

Further, in the present invention, the shape and fixing manner of the disk of the mold clamping device 13 are not limited to the above. The fixing plate may be fixed to the base like a general injection molding machine, and the pressure receiving disk may be moved in the mold opening and closing direction. The fixing plate is fixed to the base type, and the position sensor is disposed between the fixed plate and the movable plate, so that the distance between the molds can be more accurately measured, and the injection filling can be easily grasped near the imminent position F of the injection pressure. Shift of the movable plate. And there are advantages that are not easily affected by the thermal expansion of the tie rod. However, as described above, it is affected by deformation such as tilting, deflection, and the like of the fixed disk during mold clamping.

Further, in the case where the position sensor is provided between the fixed mold and the movable mold as in Patent Document 2, the distance between the molds can be more accurately measured without being affected by the thermal expansion of the mold. However, the disadvantage is that the sensor is easily deteriorated due to heat from the mold. Further, in order to change the forming mold corresponding to the difference in the light guide plate to be formed, it is necessary to provide a position sensor in each of the molds. In addition, even if the position sensor is set to be detachable with respect to the forming mold, installation and adjustment still take time.

Next, in the injection press molding method of the present embodiment, the molding dies 19 and 22 used for forming the light guide plate as a thin material will be schematically explained. The thin matter here is not necessarily limited to this, and is roughly The standard means that the flow length of the molten resin from the gate to the end is 30 times or more the thickness of the sheet, and the upper limit of the thickness means the extent that it can be filled in the cavity by the injection pressure. The type of the molded article includes, in addition to the light guide plate, various materials such as a diffusion plate, a lens, a optical disk, a plate-like body as a glass substitute, a vehicle component, and a frame material for a television.

In the movable mold 22 of the molding die, a pellet 62 for forming the cavity forming surface 62a is fixed substantially at the center of the mold main portion 61 (main mold). Further, in the mold main body portion 61, the movable frame portion 63 is attached through the spring 64. Further, with respect to the central core block 62, the surrounding movable frame portion 63 can be relatively moved by the expansion and contraction of the spring 64 described above. Further, the surface of the movable frame portion 63 on the side of the fixed mold 19 is a parting surface 63a that abuts against the fixed mold 19. Further, a gate cutting member, an ejection mechanism, and a temperature adjustment flow path (not shown) are disposed in the movable mold 22. Therefore, in the present invention, the mold main body portion 61 and the core block 62 of the movable platen 21 and the movable mold 22 are integrated and can move together.

On the other hand, in the fixed mold 19, the cavity forming block 65 and the abutting block 66 are fixed to the mold main body portion 68 (main mold). An abutting block 66 is disposed around the cavity forming block 65 for forming the cavity forming surface 65a, and the cavity forming surface 62a of the core block 62 of the movable mold 22 and the cavity forming surface 65a of the cavity forming block 65 are disposed. In the opposite direction. Further, the parting surface 66a as the abutting surface of the abutting block 66 is brought into contact with the parting surface 63a which is the abutting surface of the movable frame portion 63 of the movable mold 22, and the cavity 67 is formed inside. Further, a sprue bushing and a temperature regulating flow path (not shown) are formed in the fixed mold 19. The movable frame portion 63 of the movable mold 22 is movable relative to the core block 62, when After the mold is abutted, the distance between the cavity forming surface 62a and the cavity forming surface 65a is variable, so that the molten resin in the cavity 67 can be compressed.

Further, in the molding die used in the present invention, in addition to the injection molding die (compression molding die) in which the split faces 63a and 66a abut each other, a so-called insert die can be used, and the insert die is a movable die. The core block is inserted into the cavity portion of the fixed mold to form a cavity having a variable volume. In the case of the insert mold, the entire movable mold can be moved relative to the fixed mold to compress the molten resin in the cavity.

Next, the injection press molding method by the injection molding apparatus 11 of the present invention will be described, in particular, the setting of the approach position F or the like. As described in the above-mentioned background art, in the case of injection molding (including injection molding), the temperature of each part of the molding die and the injection press molding device 11 rises during the period of the reverse molding cycle from the start of molding. There is a problem with thermal expansion. Further, in the case of injection molding, when the compression is started, the movable mold 22 must be accurately stopped at the position where the movable mold 22 is away from the fixed mold 19, that is, the position F at which the volume of the cavity 67 is enlarged. However, as described above, when the forming mold or the like thermally expands, the position at which the fixed mold 19 and the movable mold 22 abut are changed, and the substantial distance between the approaching position F and the mold clamping position G is changed.

Then, the set clamping force f for detecting the offset position E is first set and input. In the set mold clamping force f of the present embodiment, the hydraulic pressure value detected by a pressure sensor (not shown) on the mold clamping cylinder 37 or its piping is set and input. The set clamping force f is equal to or less than the maximum clamping force. The size of the press forming device 11 is different, and it is 5 to 50% of the maximum mold clamping force. The mold using the spring as in the present embodiment is preferably between 10 and 50% of the maximum mold clamping force. In the above-described setting of the mold clamping force f, even if the maximum mold clamping force (100%) is set, there is no problem in molding, but waste is caused. The set clamping force f for detecting the offset position E can be input by the operator in accordance with the mold, or can be set to a constant ratio according to the relationship with the maximum mold clamping force at the time of shipment of the machine. Further, the offset position E is the control origin 0 of the controller which is the position sensor 42 and whose detection value is used. Next, according to the distance from the offset position E toward the mold opening direction, the mold advance limit position D, the approach position F, the cylinder switching position C, the mold protection start position B, and the mold opening and closing speed are set and input. Low speed switching position, mold opening completion position A, etc.

The approaching position F is a position at which the compressible cavity 67 is formed between the fixed mold 19 and the movable mold 22 during the injection press molding (the standby position of the movable disk 21 before the injection, etc.), as shown in Figs. 2 and 5. As shown in the figure, the mold advancement limit position D and the offset position E are positions at which the movable mold 22 is further retracted. In other words, it is the position where the molten resin compression stroke is added to the mold advance limit position D. Further, in the approach position F of the present embodiment, the offset position E is set to 0, and the mold opening position is set to a positive number. Therefore, even if the thermal expansion of the mold occurs, the offset position E can be corrected, and the movable disk 21, the pellet 62 of the movable mold 22, and the like can be stopped at the approach position F at a constant distance from the fixed mold 19. Further, the distance from the offset position E to the approaching position F is extremely short, and the mold main body portion 61 of the movable disk 21 and the movable mold 22 is made by a closed loop means such as a servo valve. Moving at a very low speed can improve the stopping accuracy.

Further, the cylinder switching position C (LS-C) is a position at which the mold clamping operation by the additional cylinder is performed by the mold closing operation of the auxiliary plunger cylinder in the mold clamping cylinder 37, and is set in the fixed mold 19 The position where the parting surface 66a and the parting surface 63a of the movable mold 22 abut each other (strictly speaking, there may be cases where they are not completely identical). In the case of using the mold clamping device of the toggle mechanism, although the setting of the cylinder switching position C is not performed, the extension of the link is not to reduce the amount of advancement of the movable mold but to increase the mold clamping force, so that it can be adjusted to The mold is abutted at the optimum position.

Next, the injection press molding method by the injection molding apparatus 11 of the present invention will be described with reference to Figs. 2 to 5, and in particular, the positioning control of the movable panel 21 toward the approaching position F will be described in accordance with the molding cycle. First, the auxiliary plunger cylinder for closing the mold is operated, and the mold closing of the movable plate 21 and the movable mold 22 is performed from the mold opening completion position A (S1). Between the mold protection start position B and the cylinder switching position C (partition surface contact position), the closed mold mold protection section is for restricting the pressure of the hydraulic oil supplied to the auxiliary plunger cylinder for closing the mold. It is prevented from being damaged by a foreign matter such as a resin. At this time, the movable disk 21 is timed by the timer while passing the mold protection start position B, and when it is not possible to reach the cylinder switching position C after a predetermined time elapses, it is determined that the abnormality has occurred and the machine is stopped (in the flow of Fig. 3, The process of the closed mold mold protection interval is omitted). Further, when the cylinder switching position C (LS-C) is reached (S2), the servo valve (not shown) is closed, the oil supply from the tank to the booster cylinder is stopped, and the high pressure is supplied from the pump to the booster cylinder. The action oil starts to pressurize (S3).

The mold protection start position B and the cylinder switching position C are controlled so as to be calculated by adding the set value to the origin 0 after the correction of the offset position E at the time of the previous molding. However, it is also possible to use the position calculated by adding the average value of the offset position E at the time of the previous molding to the set value.

Next, the core block 62 of the movable mold 22 and the like are advanced from the cylinder switching position C, and the core block 62 is advanced most. Between the reaching of the mold advance limit position D is the injection pressure mold protection section, and the mold clamping cylinder 37 is supplied. The operating oil pressure of the (auxiliary plunger cylinder and the booster cylinder) is limited to the lowest value of the spring 64 of the compressible movable mold 22, thereby preventing mold breakage due to seizure between the molds, resin residue in the cavity 67, and the like. At this time, in order to counteract the force of the spring 64, a mold clamping force of about 5 to 20% of the maximum mold clamping force is applied, and the branching rod 20 is stretched. At this time, when the mold protection abnormal value is detected before reaching the mold advance limit position D described below (S4), the mold protection is started to stop the apparatus (S13). Further, even if the mold advance limit position D cannot be reached after a predetermined period of time (S5), the mold protection is started to stop the apparatus (S13).

The mold advance limit position D is set at a position slightly longer than the mold opening side based on the previous offset position E or the average value of the offset position E up to the previous time, and is movable with the movable mold 22 The frame portion 63 is relatively retracted so that the position where the spring 64 between the movable frame portion 63 and the mold main portion 61 cannot be further contracted (the position at which the core block 62 cannot advance with respect to the movable frame portion 63) substantially coincides with or is higher than This position is slightly closer to the side of the mold side. And when the mold advance limit position D is reached, the injection pressure is ended. In the mold protection section (S6), if the movable disk 21 is to be moved in the mold closing direction, the extension of the tie bar 20 becomes remarkable, and the pressure increase of the hydraulic cylinder or the like is rapidly performed. Further, the setting of the forward limit position D is not necessary, and after the end of the injection press mold protection section by a timer or the like, when the set mold clamping force f is detected, it is judged that the offset position E has been reached. Further, in Fig. 4, with respect to the cylinder switching position C, the position of the fixed disk 15 at the forward limit position D on the right side indicates that the fixed disk 15 has moved in the direction of the injection device 14. In the fixed pattern of the fixed disk relative to the base, as the clamping force increases, the pressure plate will retreat.

Next, when the previously set set clamping force f value is detected by the pressure sensor provided in the mold clamping cylinder 37 (or its piping) (S7), it is judged that the offset position E has been reached and the movable disk 21 is made. The advancement is temporarily stopped (S8). The position of the offset position E, the movable disk 21 at the approaching position F, and the state of the molding die are as shown in Fig. 5. The set clamping force f for detecting the offset position E is mostly below the maximum clamping force, so the influence on the forming cycle is extremely small and the energy loss is small. However, the mold clamping force f is not applied but the fixed mold clamping force f is applied. Therefore, the positional deviation or the like caused by the friction between the molds can be eliminated, and a stable position can be obtained.

In the present embodiment, the value n detected by the position sensor 42 at the offset position E is 0 (n → 0), and the control origin 0 is corrected and updated in each molding cycle (S9). . The reason for this is that the mold is thermally expanded as it is repeatedly formed, and when the same set value is maintained and formed, the approaching position F approaches the mold clamping position G. Result, will Adding more than the clamping force necessary to make the molded article thin or unfilled. Further, since a mold clamping force of more than necessary is applied, the machine and the mold are broken, and the life is shortened. Further, the update of the control origin 0 at the offset position E may be performed once per plural times or by using a mathematical deviation. Further, the control position may be corrected by measuring the offset position E in accordance with predetermined conditions such as the passage of time and the temperature change of the mold. However, when the offset position E is corrected each time, the set value a of the approaching position F is added to the control origin 0 corrected at the offset position E, and the movable disk 21 or the like can be stopped at the approach position F, so In the relationship of the fixed mold 15, the movable mold 22 can be more accurately stopped at the approach position F. Further, the update of the control origin 0 of the position sensor 42 is preferably performed such that the offset position E is 0 as in the present embodiment, but the other position is used as the 0 position, and the offset position E is always updated. It is also possible for the same value.

After the control origin 0 is reset at the offset position E (S9), the operating oil is supplied to the open side of the mold clamping cylinder 37, and the movable disk 21 and the movable mold 22 (the mold body portion 61 and the core block 62) are opened toward the mold opening. The direction moves (S10). Further, in the mold opening, when the approach position F from the offset position E to the mold opening direction by the predetermined value a is detected (S11), the mold opening of the movable disk 21 or the like is stopped (S12). As described above, even if the forming mold thermally expands, the core block 62 of the movable mold 22 can be stopped at the approaching position F at a predetermined distance with respect to the fixed mold 19. The stop control of the position sensor is performed by performing closed-loop control of the detected value of the position sensor 42 and controlling the servo valve. Further, at the approaching position F, both the mold clamping side and the mold opening side of the mold clamping cylinder 37 are sealed with the hydraulic oil and are in a balanced state.

Further, at the approaching position F, the parting surface 63a of the movable frame portion 63 of the movable mold 22 abuts against the parting surface 66a of the fixed mold 19, and in the state where the spring 64 has a contraction clearance, for the variable volume mode At the hole 67, the injection of the molten resin (ejection filling) is performed from the injection device 14. In the present embodiment, the forward position of the screw is detected, the mold clamping cylinder 37 is operated again, and the movable disk 21 or the like is rapidly advanced during the injection filling, and the molten resin in the cavity 67 is compressed. The relationship between the start of injection and the start of compression is not limited to the emission, and compression may be started at the same time as the injection is started or after the injection. The mold clamping by the mold clamping cylinder 37 can be carried out according to a predetermined condition using a pressure or a plurality of stages of pressure, and most of the cases are initially clamped by the maximum mold clamping force. When the fixed disk 15 is moved as described in the present embodiment, the position of the movable disk 21 is obtained by detecting the distance between the pressure receiving disk 18 and the movable disk 21, and the movable disk 21 is clamped when the mold is clamped by the maximum mold clamping force. The mold clamping position G (the mold clamping completion position after the cooling and shrinking of the molded product) is mostly such that the tie rod 20 is stretched and moved further forward than the offset position E (but depending on the type of the molded product or the molding die, This must be the case). Further, in particular, in the type in which the fixed disk is fixed and the distance between the fixed disk and the movable plate is detected, the mold clamping position of the movable plate is not necessarily closer to the mold clamping direction (fixed disk side) than the offset position.

Further, in the present embodiment, the injection press molding device 11 uses the mold clamping cylinder 37, but the mold opening and closing mechanism uses an electric motor, and the mold clamping mechanism may use a mold clamping cylinder. Further, the mold clamping cylinder is not limited to one, and a mold clamping cylinder connected to the tie rod may be provided in the vicinity of the four corners of the fixed disk or the movable plate. In this case as well, the mold opening and closing mechanism may be either an electric motor or a hydraulic cylinder. except In addition to this, a toggle mechanism that is clamped by an electric motor or a hydraulic cylinder can also be used. In the case of the toggle mechanism, the position of the pressure plate is determined in accordance with the thickness of the mold when the mold is mounted. Moreover, the position of the movable plate is detected according to the position of the rotary encoder or the coupling of the servo motor for clamping, and the clamping force is based on the value of the tie sensor (strain sensor) and the load meter. The value, or the square moment (current value) of the electric motor, is detected. Therefore, after the start of the forming, the offset position E is detected by the tie sensor or the like, and the control origin of the rotary encoder or the like at the offset position E is reset every time. At this time, since the position of the pressure plate is not moved, the cycle is not prolonged. Further, when the forming mold is thermally expanded from a certain period of time or more from the start of forming, even if the value from the offset position E to the approaching position F is correct, the mold clamping force is changed as the bending angle of the connecting rod changes. It is advisable to retreat the position of the pressure plate.

The injection press molding method of the thin plate of the present invention and the injection press molding device for the thin plate can also be applied to the case of using a vertical mold clamping device. Further, the molding material is not particularly limited.

11‧‧‧Injection pressure forming device

12‧‧‧ Pedestal

13‧‧‧Molding device

14‧‧‧Injection device

15‧‧‧ fixed disk

18‧‧‧Pressure plate

19‧‧‧Fixed mould

20‧‧‧ tied

21‧‧‧ movable plate

22‧‧‧ movable mold

37‧‧‧Clamping cylinder

61,68‧‧‧Mold body

62‧‧‧core

63‧‧‧ movable frame

64‧‧‧ Spring

67‧‧‧ cavity

A‧‧‧Opening position

B‧‧‧Mold protection start position

C‧‧‧Cylinder switching position

D‧‧‧Mould forward limit position

E‧‧‧ offset position

F‧‧‧ imminent position

G‧‧‧ clamping position

a‧‧‧Set value

f‧‧‧Setting the clamping force

Fig. 1 is a side view of the injection press molding apparatus of the present embodiment.

Fig. 2 is a view showing the relationship between the order and the position of the injection press molding method of the present embodiment.

Fig. 3 is a flow chart showing the injection press molding method of the present embodiment.

Fig. 4 is a view showing a state of a molding die at each position of the first half of the injection press molding method of the present embodiment.

Fig. 5 is a view showing a state of a molding die at each position in the second half of the injection press molding method of the present embodiment.

A‧‧‧Opening position

B‧‧‧Mold protection start position

C‧‧‧Cylinder switching position

D‧‧‧Mould forward limit position

E‧‧‧ offset position

F‧‧‧ imminent position

G‧‧‧ clamping position

a‧‧‧Set value

Claims (4)

A method for injection molding of a thin plate, wherein the movable disk is stopped at an imminent position, the imminent position is a compressible cavity formed between the fixed mold and the movable mold, and the molten resin is ejected toward the cavity. Further, the compression is performed in the above-described approach, and the positioning control of the movable disk toward the approaching position is performed by moving the movable disk in the mold closing direction, and the setting clamping force below the maximum clamping force is detected. The offset position causes the movable disk to stop and the control origin is corrected, and the component of the set value is moved from the offset position toward the mold opening direction. The injection pressure forming method of the thin plate according to the first aspect of the invention, wherein the offset position detected by the set clamping force equal to or less than the maximum mold clamping force is used, each molding cycle or each plurality of molding cycles. Correct the control origin once. An injection molding apparatus for a thin plate stops the movable disk at an imminent position, and forms a compressible cavity between the fixed mold and the movable mold, and allows the movable plate to be melted toward the molten cavity. Further, the compression is performed in the above-described approach, and the positioning control of the movable disk toward the approaching position is performed by moving the movable disk in the mold closing direction, and the setting clamping force below the maximum clamping force is detected. The offset position causes the movable disk to stop and the control origin is corrected, and the component of the set value is moved from the offset position toward the mold opening direction. An injection molding apparatus for a thin plate according to claim 3, wherein A fixing plate for mounting a fixed mold is disposed on the base, and a pressure receiving disk is disposed on a side opposite to the fixing plate on the base; and the die opening and closing direction is between the fixed plate and the pressure receiving plate Movably provided with a movable disc for mounting a movable mold; a position sensor for detecting between the pressure plate and the movable plate, the base and the movable body Between the discs and the distance between the fixed disc and the movable disc, the position sensor detects the offset position of the set clamping force below the maximum clamping force detected by the position sensor After the movable disk, correct the control origin.