JP2008179061A - Injection molding machine and control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding machine and a control method thereof capable of seeking production efficiency even if a manufacturing cost of the injection molding machine is reduced by reducing the number of injection device relative to a mold device. <P>SOLUTION: The injection molding machine 11 where the number of mold devices 27 is larger than that of injection devices 12 is equipped with a fluid supply mechanism 53 where a molten resin fills a cavity 52, and after starting of injection, any liquid of either gas or liquid fills the cavity 52, a closing mechanism 96 for closing a resin passage 92 between the cavity 52 and a resin filling hole 51b of the mold device 27, and a moving mechanism 17 which moves at least one of the mold device 27 or the injection device 12 after closing the resin passage 92 and makes nozzle touch with the injection device 12 to another mold device 27. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an injection molding machine in which the number of mold devices is larger than the number of injection devices or a pressure holding method thereof, and in particular, pressure holding is performed on a molten resin with either a gas or a liquid. It is characterized by being applied.

It is the cooling time that takes the most time in the cycle time of a general injection molding machine. This is particularly noticeable when molding thick-walled products. Therefore, in the case of a molded product having a long cooling time such as a thick-walled product, a wasteful waiting time is generated on the injection device side after the weighing process is completed. In order to solve such problems, an injection molding machine is known in which the number of mold devices is larger than the number of injection devices described in Patent Document 1. In Patent Document 1, one injection device is disposed for three mold clamping devices A1 to A3 and a mold device, and the injection device moves to sequentially inject the mold. Therefore, even for a molded product having a long cooling time, cooling of the molded product in the mold apparatus can be completed while the injection device repeats weighing and injection, and no wasteful waiting time is generated on the injection device side.

Moreover, in a general injection molding machine, after the injection, the screw of the injection device is pressed in the forward direction while keeping the nozzle in contact with the mold to prevent cooling and shrinkage. In the meantime, however, the injection device cannot enter the metering process of rotating the screw. Therefore, in Patent Document 1, a pressure holding device is provided on the mold device side so that the injection device can shift to a measuring step immediately after injection. In the pressure retaining device of Patent Document 1, a shutoff valve is disposed in the molten resin passage, and a pressure retaining device using a cylinder is disposed on the cavity side. Then, after the injection, the shutoff valve is closed to move the injection device, and on the mold device side, the cylinder of the pressure holding device is operated to hold the pressure.

However, Patent Document 1 has the following problems. That is, since the pressure holding device is provided in the vicinity of the opening far from the cavity, the pressure holding cannot be effectively applied to the cavity. In particular, if there is a thick part in the cavity far from the gate part, the gate part is cooled and solidified first, and the holding pressure cannot be achieved. Moreover, the pressure holding device using a cylinder has a complicated structure and leads to an increase in cost. Furthermore, in Patent Document 1, provision of a pressure holding device did not lead to shortening of the cooling time.

On the other hand, what is described in Patent Document 2 is known as a method of holding pressure with a gas in order to prevent resin sink in the cavity. However, Patent Document 2 describes that simultaneous injection molding is performed on a plurality of cavities, but the combination of the injection apparatus and the mold apparatus reduces the cooling time and eliminates the waiting time of the injection apparatus. Is not disclosed. Therefore, the point of improving the production efficiency of the injection molding machine by gas holding pressure has never been assumed.

Japanese Patent Publication No. 3-74892 (Claims 1, 1 and 2) JP-A-9-239788 (Claims 1, 0026, FIG. 3)

In the present invention, in view of the above problems, the injection molding machine and the control of the injection molding machine that can pursue production efficiency even if the number of injection devices for the mold device is reduced to suppress the manufacturing cost of the injection molding machine. It aims to provide a method. An injection molding machine and a control method for the injection molding machine that can reduce the molding cycle time by shortening the cooling time can be provided, especially in the case of thick molded products. The purpose is to do.

The injection molding machine according to claim 1 of the present invention is an injection molding machine in which the number of mold devices is larger than the number of injection devices. A fluid supply mechanism for injecting any one of the liquids, a closing mechanism for closing the resin passage between the cavity of the mold device and the resin injection hole, and at least one of the mold device or the injection device after closing the resin passage. And a moving mechanism for moving the injection device to make a nozzle touch with respect to another mold device.

According to a second aspect of the present invention, there is provided the injection molding machine according to the first aspect, wherein the mold clamping device for clamping the mold device includes a main mold clamping device used at the time of injection by the injection device and a moving mechanism. And a sub-clamping device used when the device is moved.

According to a third aspect of the present invention, the injection molding machine according to the first or second aspect is characterized in that the fluid supply mechanism can continuously supply the fluid even when the mold apparatus is moved.

An injection molding machine according to a fourth aspect of the present invention is the injection molding machine according to any one of the first to third aspects, wherein the closing mechanism for closing the resin passage includes a resin passage made of a hot runner and a part of the resin passage. And a ball check that makes it impossible for the molten resin to flow when the molten resin flows in the opposite direction to the injection and the molten resin flows in the opposite direction to the injection. Is provided.

The method for controlling an injection molding machine according to claim 5 of the present invention is the method for controlling an injection molding machine in which the number of mold devices is larger than the number of injection devices. After injecting molten resin into the cavity, the resin passage between the cavity and the resin injection hole is closed by the closing mechanism before and after supplying either gas or liquid fluid from the fluid supply mechanism to the cavity. In addition, at least one of the mold apparatus or the injection apparatus is moved by the moving mechanism, the injection apparatus is nozzle-touched to another mold apparatus, and the fluid is supplied from the fluid supply mechanism into the cavity to hold the molten resin with pressure. It is characterized by pouring.

According to a sixth aspect of the present invention, there is provided a method for controlling an injection molding machine according to the fifth aspect, wherein the measurement is performed by the injection device in parallel with the holding pressure applied to the molten resin by the fluid.

According to a seventh aspect of the present invention, there is provided a method for controlling an injection molding machine according to the fifth or sixth aspect, wherein a fluid supply start timing and a fluid supply time according to a change in volume or shape of a cavity of a mold apparatus , Wherein at least one of the pressures of the fluid can be changed.

According to the injection molding machine and the injection molding machine control method of the present invention, in an injection molding machine in which the number of mold devices is larger than the number of injection devices, the molten resin is injected into the cavity after the start of injection of the molten resin. Or a fluid supply mechanism for injecting one of the liquids, a closing mechanism for closing the resin passage between the cavity of the mold apparatus and the resin injection hole, and the mold apparatus or the injection apparatus after the resin passage is closed. A moving mechanism that moves at least one of the nozzles and touches the injection device with another mold device, and supplies the fluid from the fluid supply mechanism into the cavity to apply pressure to the molten resin. Even if the number of injection devices for the mold device is reduced to reduce the manufacturing cost of the injection molding machine, the production efficiency can be pursued.

The injection molding machine and the injection molding machine control method of the present invention will be described with reference to FIGS. FIG. 1 is a front view of an injection molding machine according to the present embodiment. 2 is a cross-sectional plan view taken along the line AA in FIG. FIG. 3 is a circuit diagram of the fluid supply mechanism. FIG. 4 is a schematic sectional view of the mold apparatus.

As shown in FIGS. 1 and 2, the injection molding machine 11 includes an injection device 12, a base 13 of the injection device 12, a main mold clamping device 14 disposed below the base 13, and a main mold clamping device. 14. A pedestal 15 including a pedestal 15 provided on the outer side adjacent to an opening that is orthogonal to four horizontal directions, and a clamping position 15a and an extraction position 15b surrounded by the opening inside the main mold clamping device 14. A hydraulic cylinder 17 is provided as a moving mechanism for individually moving the four sub mold clamping devices 16 between the sub-clamping devices 16.

As shown in FIG. 1, the main mold clamping device 14 includes a lower plate 18 serving as a gantry, a main cylinder 19 provided in the center of the lower plate 18, and a ram that is removably fitted into the main cylinder 19. 20 is a vertical mold clamping device that includes 20, four tie bars 21 erected at the four corners of the lower board 18, and an upper board 22 that fixes the upper ends of the tie bars 21 at the four corners. Openings are formed by the inner side surfaces of the two adjacent tie bars 21, the upper surface of the lower board 18, and the lower surface of the upper board 22, and the four-sided openings are orthogonal to each other. Further, the pressing position 15 a is formed by a region surrounded by the four openings, the upper surface of the lower board 18, and the lower surface of the upper board 22. When the sub mold clamping device 16 is carried into and out of the clamping position 15a and the sub mold clamping device 16 is positioned at the pressure clamping position 15a, the ram 20 rises and presses the lower mold plate 23, and the upper mold plate A mold device 27 composed of an upper mold 26 attached to the lower surface of 24 and a lower mold 25 attached to the upper surface of the lower mold plate 23 is clamped.

As shown in FIG. 1 in which the take-out robot 54 is omitted and FIG. 2 in which the take-out robot 54 is described, the sub mold clamping device 16 is a lower mold plate that is placed on a transfer table 28 that constitutes a part of the moving mechanism. 23 and four sub-clamping cylinders 29 attached between the lower mold plate 23 and the upper mold plate 24. The sub-clamping cylinder 29 has cylinder portions attached in the vicinity of the four corners of the lower mold plate 23 so as to surround the mold apparatus 27, and rod portions attached in the vicinity of the four corners of the upper mold plate 24. Note that the sub-clamping cylinder may be provided at two positions in the diagonal direction, and a guide tube and a guide bar may be provided at the other two positions. Further, an ejector device 30 is disposed below the lower mold plate 23 of each sub mold clamping device 16.

The moving mechanism is for conveying the sub-clamping device 16 between the take-out position 15b outside the opening and the pressure-clamping position 15a in the main mold-clamping device 14; Conveying means. As shown in FIGS. 1 and 2, the conveying means is a base that is disposed adjacent to the four sides of the lower board 18 at the same height as the upper face of the lower board 18 that also serves as the base of the main mold clamping device 14. 15, the conveying rollers 31 disposed on the upper surface are disposed in the row direction, and the conveying table 28 of each sub mold clamping device 16 is small between the pressing position 15a and the take-out position 15b via the conveying rollers 31. It is moved by the driving force. The moving mechanism moves the sub mold clamping device 16 in this embodiment, but may move the injection device as in Patent Document 2 or another embodiment described later.

The injection device 12 is attached to the base 13. A cylindrical portion 32 erected on the upper surface of the upper plate 22 of the main mold clamping device 14, a plurality of rods 33 that are slid and guided by the cylindrical portion 32, and a rectangular shape in plan view that fixes the upper end portion of the rod 33. Base 34, a housing part 36 that is swingably supported by a pivot shaft 35 provided on the base 34, a heating cylinder 37 into which a screw (not shown) attached to the lower surface of the housing part 36 is fitted, and a heating cylinder 37 The nozzle 38 screwed at the tip of the nozzle, the shut-off valve mechanism 39 that is an opening and closing mechanism of the resin passage in the nozzle 38, and the hydraulic pressure that drives the screw provided in the housing portion 36 and inserted in the heating cylinder 37 to move forward and backward. Screw forward / rearward drive means 40 comprising a combination of a cylinder device or servo motor and a ball screw, and a screw rotation comprising a hydraulic or electric motor connected to the screw forward / backward drive means 40 and the screw. Drive means 41, lift means 42 comprising a cylinder device provided between the base 34 and the base 13 and driving the base 34 up and down, and provided between the base 34 and the housing part 36, the housing part 36 is driven to swing. And swinging means 43 comprising a cylinder device. Such an injection device 12 operates the swinging means 43 so that the heating cylinder 37 is substantially vertical and the nozzle 38 is in a state where the nozzle is touched by the sprue bush 51 of the upper mold 26. Plasticizing and melting is performed in the heating cylinder 37 based on the screw rotation by the screw rotation driving means 41, the molten material is stored below the screw in the heating cylinder 37, and the nozzle 38 is touched by the nozzle of the sprue bush 51 of the upper mold 26. After being pressed against the surface 51a, the screw is moved forward (downward) by the screw forward / backward drive means 40 to the cavity 52 in the mold apparatus 27 composed of the upper mold 26 and the lower mold 25 in which the molten material is clamped together. Eject.

Further, a nitrogen gas supply mechanism 53 which is a fluid supply mechanism is located in the lower right in FIG. Further, in FIG. 2, the molded product take-out robots 54 and 54 are located at the upper right and the lower left, and each take-out robot 54 has two sub-clamping devices 16 respectively. When in the take-out position 15b, the molded product is taken out. Also located at the upper left is a hydraulic device 55, which is connected to each hydraulic cylinder such as the main cylinder 19 via hydraulic piping and valves. The hydraulic device may be disposed below the nitrogen gas supply device or on the side of the injection device.

Next, the nitrogen gas supply mechanism 53 of this embodiment will be described with reference to FIGS. The nitrogen gas supply mechanism 53 is provided with a nitrogen gas generator 56 that takes in air from the outside and generates nitrogen. The nitrogen gas generator 56 is connected to the low pressure tank 59 via a pipe line 58 with a check valve 57 so that the nitrogen gas generated by the nitrogen gas generator 56 is stored in the low pressure tank 59. Yes. The low-pressure tank 59 is connected to the high-pressure gas generator 61 via the pipe line 60, and the nitrogen gas sent from the low-pressure tank 59 is pressurized to a high pressure by the compressor in the high-pressure gas generator 61. A main pipe 63 with a check valve 62 from the high-pressure gas generator 61 branches off a branch pipe 65 connected to the high-pressure tank 64 on the way, and the branch pipe 65 has a pressure-adjustable relief valve 66. Is connected. In addition, an electromagnetic opening / closing valve 67 is also provided downstream of the branch position of the main pipe 63 (on the mold apparatus side), and the auxiliary pipe 68 connected to each mold apparatus 27 on the downstream side of the electromagnetic opening / closing valve 67. Are branched. The high-pressure gas generator 61, the high-pressure tank 64, the check valve 62, and the electromagnetic on-off valve 67 constitute one unit 69 in the example of FIG. The sub-pipe 68 is made of a flexible pressure hose. The pressure hose of the sub-pipe 68 is surrounded by a protective member so as to protect the hose and move the sub-pipe 68 to a fixed position when the mold device 27 connected to the sub-pipe 68 is moved. Has been. In the present embodiment, a cable bear (registered trademark) 68a is used as a protection member for the sub pipe 68. In addition, you may make it switch to the said secondary pipe line by a direction switching valve.

The gas supply mechanism for each mold apparatus 27 will be described as an example. The sub-pipe 68 is connected to an electromagnetic on-off valve 70, and a check valve 71 is attached downstream thereof. Further, a branch pipe 73 connected to the sub tank 72 is branched further downstream of the sub pipe 68, and a relief valve 74 capable of adjusting the pressure is connected to the branch pipe 73. Further, an electromagnetic on-off valve 75 is provided in the sub pipe 68 further downstream from the branch position of the branch pipe 73 to the sub tank 72, and the sub pipe 68 on the downstream side is connected to the mold device 27. Yes. Further, an exhaust branch line 76 is branched from the sub-pipe 68 downstream of the electromagnetic open / close valve 75, and an electromagnetic open / close valve 77 is also provided in the branch line 76. Actually, as shown in FIGS. 1 and 2, the electromagnetic opening / closing valves 70, 75, 77 and the check valve 71 are incorporated in the manifold block 78 and are arranged on the side of the mold apparatus 27 together with the sub tank 72. As described above, the manifold block 78 and the sub tank 72 are disposed on the side of the mold device 27 and moved together with the mold device 27. The electromagnetic on-off valve 75 and the sub tank are located as close as possible to the mold device 27. This is because the provision of 72 is superior in responsiveness when supplying nitrogen gas into the cavity 52. Further, the nitrogen gas supply mechanism 53 is provided with a control device 79, which is connected to each device and an electromagnetic on-off valve by a signal line, and can control each of them. In the nitrogen gas supply mechanism 53, a nitrogen gas temperature adjusting device is not shown, but by providing a temperature adjusting device and controlling the nitrogen gas at a constant temperature, highly repeatable results can be obtained.

Next, the main part of the mold apparatus 27 will be described. The mold apparatus 27 includes a lower mold 25 and an upper mold 26, and a cavity 52 is formed when the molds are aligned. The cavity 52 of the present embodiment has a thick portion 81, and the lower mold 25 is provided with a nozzle pin 83 for supplying nitrogen gas to the thick portion 81 in the cavity 52. The nozzle pin 83 is formed with an injection hole 84 through which a molten resin having a diameter of 20 μm to 50 μm does not enter at the tip, and the injection hole 84 of the nozzle pin 83 protrudes from the cavity forming surface 85 at the base of the nozzle pin 83. A gas supply line 86 is formed inside the nozzle pin 83 so as to communicate with the injection hole 84, and is connected to the sub line 68 via a line 87 inside the lower mold 25. The nozzle pin 83 for supplying nitrogen gas is provided at a position where the molded product P is as inconspicuous as possible. The number of nozzles is not limited as long as it is at least one, and it is sufficient that nozzle pins are provided in at least one of the lower mold and the upper mold. In addition, you may provide the electromagnetic on-off valve which opens and closes this pipe line in the pipe line in a metal mold apparatus. An ejector plate 88 and ejector pins 89 that move up and down in conjunction with the drive of the ejector device 30 are disposed in the lower mold 25 that is a core mold. In the above, when the molded product P has the thick part 81 having a thickness of about 5 mm to 50 mm and the hollow part P1 is formed inside, the protruding amount of the injection hole 84 at the tip of the nozzle pin 83 from the cavity forming surface 85 is thick. The width of the meat portion 81 is about 1/5 to 1/2. In addition, when the molded product has a thickness of about 1 mm to 8 mm and gas holding pressure is applied while releasing the side that is the back side of the molded product instead of the hollow part, the nozzle injection hole almost protrudes from the back surface forming surface in the cavity. What is not used is used.

On the other hand, the upper mold 26 is provided with a sprue bush 51 having a nozzle touch surface 51a with which the nozzle 38 abuts and a resin injection hole 51b. A hot runner 90 is connected inside the sprue bush 51. The hot runner 90 has a structure in which a heater 91 is disposed around the hot runner 90 and the molten resin in the internal resin passage 92 (runner portion) is not solidified by the heat generated by the heater 91. The tip of the hot runner 90 communicates with the cavity 52 via the nozzle portion 93 of the hot runner 90. The resin passage 92 of the hot runner 90 of this embodiment is provided with a closing mechanism that closes the resin passage. Explaining the closing mechanism, the resin passage 92 is a diameter-expanded portion 94 whose diameter is partially enlarged. Inside the enlarged diameter portion 94, a ball check 96 having a diameter larger than that of the other small diameter portions 95 is disposed. Further, on the tapered surface (or spherical surface) 97 on the cavity 52 side of the enlarged diameter portion 94, protrusions 98 are formed at several places in the circumferential direction, and when the ball check 96 is on the cavity 52 side, the protrusion Only the portion 98 is brought into contact therewith. Therefore, the taper surface 97 other than the ball check 96 and the protrusion 98 is not in contact with each other, and a gap through which the molten resin can pass is formed. Further, since the protruding portion 98 is not formed on the tapered surface (or spherical surface) 99 on the resin injection hole 51b side of the enlarged diameter portion 94, the ball check 96 and the tapered surface 99 are in contact with each other over the entire circumference. The passage 92 is closed.

The closing mechanism disposed in the resin passage between the resin injection hole and closing the resin passage may close the resin passage by a hydraulic cylinder or the like. Furthermore, when a cold runner (cold sprue) is used as a closing mechanism, nitrogen gas is supplied after the start of injection, and the runner or sprue is solidified by cooling, so that no back flow of the molten resin occurs. Thereafter, the nozzle of the injection device 12 is retracted.

Next, the control method of the injection molding machine 11 of this embodiment is demonstrated. First, one of the set of the four sub mold clamping devices 16 and the mold device 27 is a hydraulic cylinder as a moving mechanism from the take-out position 15b to the pressure clamping position 15a surrounded by the opening inside the main mold clamping device 14. It is carried in by driving 17. At this time, the mold apparatus 27 is closed by lowering the upper mold plate 24 and the upper mold 26 by the sub mold clamping apparatus 16. Next, the main cylinder 19 of the main mold clamping device 14 is operated to raise the ram 20, and the lower mold 25 and the upper mold 26 of the mold apparatus 27 are pressed and clamped via the lower mold plate 23. At the same time, the mold device 27 is also operated so as to press the sub mold clamping cylinder 29 of the sub mold clamping device 16. Next, the screw forward / reverse drive means 40 of the injection device 12 is driven to advance the screw and inject molten resin into the cavity 52 in the mold device 27. At this time, since the ball check 96 in the enlarged diameter portion 94 of the hot runner 90 is pressed against the protrusion 98 on the cavity 52 side, molten resin can be supplied to the cavity 52 from the gap between the ball check 96 and the tapered surface 97. It is. The injection amount at this time includes a full shot method in which a molten resin substantially equal to the volume of the cavity 52 is injected and a short shot method in which a molten resin smaller than the volume of the cavity 52 is injected, but is selected according to the purpose. Is done.

When the molten resin starts to be injected into the cavity 52, next, nitrogen gas is supplied to the cavity 52 from a nitrogen gas supply mechanism 53 that is a fluid supply mechanism. Regarding the gas supply start timing at this time, the molten resin pressure in the cavity 52 or in the heating cylinder 37 including the nozzle 38, whether it is a delay time from the start of injection or by detecting the advance position of the screw. May be performed. When nitrogen gas is started to be supplied into the cavity 52 from the injection hole 84 of the nozzle pin 83, the portion of the molten resin that comes into contact with or adjacent to the cavity forming surface 85 is already solidified. Nitrogen gas spreads to form a hollow portion P1 in a portion where the temperature of the molten resin in the vicinity of the separated central portion is not lowered and has high fluidity. A portion of the molten resin that has lost its place at the same time as the hollow portion P1 is formed by the nitrogen gas flows through the nozzle portion 93 of the hot runner 90 through the enlarged diameter portion 94 in the opposite direction to the injection time, and the ball check 96 is pressed against the taper surface 99 on the resin injection hole 51b side in a state where there is no gap between the two, thereby making it impossible for the molten resin to flow. The supply pressure of the nitrogen gas needs to be higher than the pressure of the molten resin supplied into the cavity 52, and is preferably about 15 MPa to 60 MPa, but can be adjusted as appropriate.

Next, when the resin passage 92 between the cavity 52 and the resin injection hole 51b which is nozzle-touched to the injection device 12 is closed by the ball check 96 which is a closing mechanism, the main cylinder of the main mold clamping device 14 is next. 19 is operated to lower the ram 20 to release the mold clamping of the mold apparatus 27 by the main mold clamping apparatus 14. At this time, the sub-clamping cylinder 29 of the sub-clamping device 16 continues to clamp the mold device 27. Next, the sub mold clamping device 16 is moved from the pressure clamping position 15a to the take-out position 15b by a hydraulic cylinder 17 as a moving mechanism. In this case, the gas holding pressure by supplying nitrogen gas into the cavity 52 of the mold apparatus 27 is continuously performed.

On the other hand, on the injection device 12 side, when the injection is completed, the shut-off valve mechanism 39 is simultaneously operated before releasing the mold clamping by the main mold clamping device 14, the nozzle 38 is closed, and the next measurement process is started. When the sub mold clamping device 16 is moved, in order to avoid interference between the sprue bush 51 of the mold device 27 and the nozzle 38, the elevating means 42 is operated to slightly raise the injection device 12. Next, another sub-clamping device 16 out of the four units is moved from the take-out position 15b to the pressure-clamping position 15a by the hydraulic cylinder 17 of the moving mechanism, and similarly, mold clamping, injection, gas supply, passage A process such as occlusion is performed. Then, the mold is taken out again to the take-out position 15b while the mold clamping and the gas holding pressure by the sub mold clamping device are continued. In this way, by performing the gas holding pressure directly in the cavity 52 of the mold device 27, the gate can be compared with the case where the holding pressure is applied from the injection device 12 or the case where the holding pressure is applied from the vicinity of the sprue bush 51. Holding pressure can be applied even after cooling and solidification. Further, it is possible to prevent sink marks by applying pressure to a desired portion such as the thick portion 81 in the cavity 52.

Then, four sub mold clamping devices 16 are sequentially sent to the pressure clamping position 15a, and pressure holding is performed after injection. During this time, the sub mold clamping device 16 that has completed the injection is cooled in a state where the holding pressure is applied by the nitrogen gas at the take-out position 15b. Therefore, the cooling solidification time can be shortened by making the inside of the thick portion 81 hollow. When the cooling is completed, the sub mold clamping cylinder 29 of the sub mold clamping apparatus 16 is operated to raise the upper mold plate 24 and the upper mold 26 to open the mold apparatus 27, and the ejector apparatus 30 ejects the ejector pins 89 and the like. And the molded product P is ejected, and the molded product P is taken out by the take-out robot 54. The take-out robot 54 can take out a molded product from the side of the nitrogen gas supply mechanism 53 of the mold apparatus 27 where the cable bear (registered trademark) 68a, the sub tank 72, and the manifold block 78 are not provided. Then, the sub-clamping device 16 and the mold device 27 that have completed the removal of the molded product P are closed again by the sub-clamping cylinder 29, and are moved to the press-clamping position 15a again in the order.

Next, the operation of the nitrogen gas supply mechanism 53 will be described with reference to FIG. The nitrogen gas generating device 56 is always operating during molding, and generates nitrogen gas from the atmosphere. The generated nitrogen gas is stored in a low-pressure tank 59 and sent to a high-pressure gas generator 61 that is always operated during molding, and is replaced with high-pressure nitrogen gas. The high-pressure nitrogen gas is stored in the high-pressure tank 64 via the check valve 62, and is released from the relief valve 66 when the pressure rises above the set value. The electromagnetic on-off valve 67 is provided in the unit from the beginning for use with a single mold apparatus, and is normally open during normal molding in this embodiment. Then, the high pressure nitrogen gas is also stored in the sub tank 72, and the nitrogen gas is released from the relief valve 74 when the pressure is higher than the setting. Then, when molding is started and injection into the first mold device 27 is started, a delay timer from the start of injection is activated in the control device of the injection molding machine 11 (not shown), and when the set time is reached, the control device 79 and The electromagnetic on-off valves 70 and 75 are opened via the signal lines. As a result, high-pressure nitrogen gas is supplied from the high-pressure tank 64 and the high-pressure gas generator 61 into the cavity 52 in addition to the nitrogen gas in the sub tank 72. Then, after the resin passage 92 is closed by the movement of the ball check 96, as the hollow portion P1 having a predetermined volume is formed in the cavity 52, the nitrogen gas inside the hollow portion P1 becomes a high pressure. Since additional supply of nitrogen gas becomes impossible, the pressure of the nitrogen gas in the sub tank 72 is increased again. When the pressure of the nitrogen gas in the sub tank 72 is further increased by closing the electromagnetic on-off valve 75, the electromagnetic on-off valve 70 is closed, and the high-pressure tank 64 before the next injection to the second mold apparatus 27 is started. The high-pressure nitrogen gas sent from the high-pressure gas generator 61 is again stored therein.

Then, when injection into the second mold apparatus 27 is started next, the electromagnetic on-off valves 70 and 75 of the sub-pipe 68 connected to the second mold apparatus 27 are opened in the same manner as described above, Nitrogen gas from the high-pressure tank 64 and from the high-pressure gas generator 61 is supplied into the cavity 52. Thereafter, the electromagnetic on-off valve 75 and the like are closed, and the nitrogen gas is charged again into the sub tank 72 and the high pressure tank 64. Similarly, the supply of nitrogen gas and the charging of the tank are repeated for the third mold apparatus 27 and the fourth mold apparatus 27. At the same time, when the molten resin in the cavity 52 of the first mold unit 27 is formed with a hollow portion P1 pressurized by high-pressure nitrogen gas and solidifies without causing sink, the electromagnetic on-off valve 75 is closed. In this state, the electromagnetic on-off valve 77 is opened, and the nitrogen gas in the hollow portion P1 is released to the atmosphere via the branch line 76. Note that the nitrogen gas in the hollow portion P1 may be recycled. The operations of the electromagnetic on-off valves 70, 75, 77 and the like during the above are all performed by signals from the control device 79. Then, the mold is opened and the molded product is taken out.

In addition, when the molded product is different depending on each mold device 27, and the injection pressure, the thickness of the thick portion 81, the volume of the hollow portion P1, and the like are different, a change in the set pressure of the sub tank 72 or a pressure control valve (not shown) is provided. It is possible to change the gas pressure by performing attachment control or the like. It is also possible to change the timing for starting the nitrogen gas supply and the timing for ending the nitrogen gas supply (fluid supply time) by changing the timing for opening and closing the electromagnetic on-off valves 70 and 75. Needless to say, each control is also changed when the mold apparatus 27 is replaced with a mold for another molded product.

Next, an injection molding machine 100 according to another embodiment will be described with reference to FIG. In the example of FIG. 5, a plurality of sub mold clamping devices 102 to which the mold device 101 is attached are arranged in a straight line. On the other hand, the main mold clamping device 103 can move between the sub mold clamping devices 102 in order to perform mold clamping only at the time of injection. Further, one injection device 104 is disposed in the horizontal direction, and a shut-off valve is attached to the nozzle 105. Further, the injection device 104 is capable of nozzle touching, forward / backward movement, and parallel movement by the moving mechanism of the rail 106 and driving means (not shown). A valve that is a closing mechanism is provided between the cavity (not shown) of the mold apparatus 101 and the resin injection hole, and nitrogen gas is supplied to the cavity from a nitrogen gas supply device (not shown). It is possible. Accordingly, a resin injection hole that is nozzle-touched to the cavity and the injection device 104 before and after the molten resin is injected from the injection device 104 into the cavity in the mold device 101 and gas is supplied from the gas supply mechanism to the cavity. The resin passage between the two is closed by a closing mechanism, gas is supplied from the supply mechanism into the cavity, and the molten resin can be held with the gas. At the same time, the injection device 104 is moved backward, parallel, and advanced by the moving mechanism, and the injection device 104 is nozzle-touched to another mold device 101. During that time, the next molten resin is plasticized and measured in the heating cylinder 107. can do. In another embodiment, the main mold clamping device 103 is moved, but there may be no auxiliary mold clamping device, and a normal mold clamping device may be attached to each mold device.

The present invention is not enumerated one by one, but is not limited to that of the above-described embodiment, and it goes without saying that those skilled in the art also apply modifications made in accordance with the spirit of the present invention. is there. Since the present invention aims to eliminate the waiting time of the injection apparatus during the cooling time, if there are more mold apparatuses than the number of injection apparatuses, for example, two injection apparatuses Alternatively, a combination of 6 mold apparatuses may be used. Further, the mold clamping device and the mold device including the main mold clamping device may move, and the injection device may be capable of only moving forward and backward and turning during maintenance. Furthermore, only a large number of mold apparatuses may move, the mold clamping apparatus may be fixedly provided, and the injection apparatus may be provided so as to be capable of only forward and backward movement and turning movement during maintenance as described above. There are various types of movements of the mold device, such as those that rotate like a rotary injection molding machine and those that move linearly. Furthermore, the mold clamping device may perform mold clamping in either the horizontal direction or the vertical direction. Moreover, although the example of the horizontal direction and the vertical direction was disclosed about the injection device, the type which uses a screw and a plunger together may be used. In the present invention, the nozzle of the injection device is generally provided with an open / close valve such as a shut-off valve, a rotary valve, etc., but the time required for measurement after injection or after the nozzle touches the next mold device is measured. Installation of an open / close valve is not essential if there is sufficient margin.

The material used for the injection molding machine is generally a thermoplastic resin, but the type is not limited and does not exclude thermosetting resins or light metal materials. The fluid supplied into the cavity may be either gas or liquid. In the case of using a gas, an inert gas other than nitrogen gas may be used as long as the gas does not have reactivity with the molten resin. For example, helium gas, argon gas, or air may be used as it is. The liquid may be water or alcohol.

It is a front view of the injection molding machine of this embodiment. It is an AA arrow cross-sectional top view in FIG. It is a circuit diagram of a fluid supply mechanism. It is a schematic sectional drawing of a metal mold apparatus. It is a top view of the injection molding machine of another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Injection molding machine 12 Injection apparatus 14 Main mold clamping apparatus 16 Sub mold clamping apparatus 17 Hydraulic cylinder (movement mechanism)
27 Mold device 51b Resin injection hole 52 Cavity 53 Nitrogen gas supply mechanism (fluid supply mechanism)
92 Resin passage 96 Ball check (blocking mechanism)
P Molded product P1 Hollow part

Claims (7)

In an injection molding machine in which the number of mold devices is more than the number of injection devices,
A fluid supply mechanism for injecting either a gas or a liquid into the cavity after injection of molten resin into the cavity; and a closing mechanism for closing a resin passage between the cavity of the mold apparatus and the resin injection hole; ,
An injection molding machine comprising: a moving mechanism for moving at least one of the mold device or the injection device after the resin passage is closed and causing the injection device to make a nozzle touch with respect to another mold device. The mold clamping device for clamping the mold device includes a main mold clamping device used at the time of injection by the injection device and a sub mold clamping device used at the time of movement of the mold device by the moving mechanism. The injection molding machine according to claim 1. The injection molding machine according to claim 1 or 2, wherein the fluid supply mechanism is capable of continuously supplying the fluid even when the mold apparatus is moved. The closing mechanism for closing the resin passage is:
A resin passage composed of a hot runner, a diameter-expanded portion in which a part of the resin passage is enlarged, and the molten resin flows through the inside of the enlarged-diameter portion in a direction opposite to the injection direction. The injection molding machine according to any one of claims 1 to 3, further comprising a ball check that disables the flow of the molten resin. In the method of controlling an injection molding machine in which the number of mold devices is more than the number of injection devices,
After injecting molten resin from the injection device into the cavity in the mold apparatus, before and after supplying either gas or liquid fluid from the fluid supply mechanism to the cavity, the cavity and the resin injection hole The resin passage is closed by a closing mechanism, and at least one of the mold device or the injection device is moved by a moving mechanism to cause the injection device to make a nozzle touch with respect to another mold device, and the fluid in the cavity A control method for an injection molding machine, wherein the fluid is supplied from a supply mechanism to apply pressure to the molten resin. 6. The method of controlling an injection molding machine according to claim 5, wherein weighing is performed by an injection device in parallel with the holding pressure applied to the molten resin by the fluid. 6. The apparatus according to claim 5, wherein at least one of a timing to start supplying the fluid, a fluid supply time, and a pressure of the fluid can be changed according to a change in volume or shape of the cavity of the mold apparatus. 7. A method for controlling an injection molding machine according to 6.

Images