JP2015044392A - Operation method of injection molding machine to witch stack mold is attached - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operation method that prevents drooling phenomenon and air entrainment into a molten resin in an injection molding machine to which a stack mold is attached.SOLUTION: A stack mold (2) is composed of a stationary side mold (31) on the stationary plate (6) side, a movable side mold (32) on the movable plate (10) side, and an intermediate mold (33). A snorkel (40) of a fixed length to introduce a molten resin is installed to the intermediate mold (33) and inserted into an open hole bored in the stationary side mold (31). In an injection molding machine (1), a nozzle (28) of an injection unit (4) is brought into contact with the snorkel (40) by a predetermined touching force. When the stack mold is opened or closed, the injection unit is moved back and forth by driving a servomotor (24) so that the touching force is kept in a predetermined range. The nozzle (28) is thus kept in contact with the snorkel (40) even while the injection molding machine is operated to be opened or closed.

Description

  The present invention includes a fixed mold attached to a stationary platen, a movable mold attached to the movable platen, and an intermediate mold provided between the fixed mold and the movable mold. The present invention relates to an operation method in an injection molding machine to which a stack mold is attached.

  As is well known in the art, an injection molding machine comprises a mold clamping device and an injection device. The mold clamping device is fixed to a bed, a movable plate that opens and closes to the fixed plate, and a movable platen. And a mold clamping mechanism such as a toggle mechanism for driving the panel. The so-called stack mold is a fixed mold attached to the fixed platen, a movable mold attached to the movable platen, and an intermediate mold provided between the fixed mold and the movable mold. It consists of a mold. The fixed side mold, the intermediate mold, and the movable side mold are connected to each other by a rack and pinion mechanism, a link mechanism, a piston cylinder mechanism, and the like, and the mold is opened and closed in conjunction with each other. That is, when the movable platen is driven with respect to the fixed platen, the intermediate mold is also driven in conjunction with this drive. In this way, the fixed mold, the intermediate mold and the movable mold are clamped, and cavities are formed between the fixed mold and the intermediate mold and between the intermediate mold and the movable mold. It has come to be. The number of intermediate molds can be two as well as one. Then, when the mold is clamped, a cavity is also formed between the two intermediate molds. In this way, the stack mold is more productive because multiple cavities are formed in the mold clamping direction, and the required mold clamping force does not change even if the number of cavities increases. do not need.

  There are various types of stack molds, and FIGS. 3A and 3B show first and second types of stack molds 51a and 51b that are opened and closed by a rack and pinion mechanism 61. FIG. . In the first type of stack mold 51a, as shown in FIG. 3A, the injection device 52 is provided on the stationary platen 53 side, and the nozzle 54 of the injection device 52 is a fixed-side mold 55. Is touching. More specifically, the fixed side manifold 56 provided in the fixed side mold 55 is touched. The stationary side manifold 56 faces a manifold body 58 provided in the intermediate mold 57. Accordingly, when the movable platen 59 is driven, the movable side mold 60, the intermediate mold 57, and the fixed side mold 55 are clamped, the fixed side manifold 56 and the manifold body 58 are connected, and the resin passage communicates. When the molten resin is injected from the injection device 52, the molten resin is supplied to the manifold main body 58 and branched in the manifold main body 58. One is a cavity formed between the fixed mold 55 and the intermediate mold 57, and the other is an intermediate mold. Injected into cavities formed between 57 and the movable mold 60.

  In the second type of stack mold 51b, as shown in FIG. 3A, the manifold body 58 in the intermediate mold 57 is provided with a snorkel 62 extending in the direction of the injection device 52, and the snorkel. 62 is freely insertable into the through hole provided in the fixed mold 55. The nozzle 54 of the injection device 52 is separated from the snorkel 62 by a predetermined distance. When such a stack mold 51b is clamped, the snorkel 62 moves to the right in the drawing with the movement of the intermediate mold 57 and touches the nozzle 54. If it does so, it can inject like the 1st kind of stack mold 51a.

  In any type of stack mold 51a, 51b, the resin passage is cut when the mold is opened. That is, in the first type stack mold 51a, the fixed-side manifold 56 and the manifold body 58 are cut when the mold is opened, and in the second type stack mold 51b, the nozzle 54 is separated from the snorkel 62 when the mold is opened. End up. If so, there is a possibility that so-called sag that causes the resin to leak from these portions or air may be caught in the molten resin.

JP-A-5-345335 JP-A-8-118403

  Patent Document 1 describes a stack mold that prevents the occurrence of such drooling into a molten resin and the entrainment of air. The stack mold described in Patent Document 1 is similar to the first type of stack mold 51a described above, but in this stack mold, a predetermined valve is provided in the resin passage on the manifold body side. This valve is urged by an elastic member, and the manifold body is connected to the fixed manifold, so that it opens when molten resin is injected from the injection device at a predetermined injection pressure, and the injection pressure decreases. Then it automatically closes. Accordingly, after the injection / holding step is performed, the valve is closed when the resin pressure from the injection device decreases. Then, even if the mold is opened and the fixed manifold and the manifold body are separated, the resin does not leak from the manifold body side, and air does not enter the molten resin.

  Patent Document 2 describes an injection molding machine 64 to which a stack mold 51c similar to the second type stack mold 51b is attached, as shown in FIG. The members having the same functions as those of the first and second types of stack molds 51a and 51b are given the same reference numerals, and the description thereof is omitted. However, in the injection molding machine 64 described in Patent Document 2, the injection device 52 is a bed. B is slidably provided. Then, connecting rods 65, 65 are fixed to the intermediate mold 57, and these connecting rods 65, 65 are inserted through through holes opened in the fixed platen 53. The injection device 52 is formed with a flange portion 67 having cylinders 66 and 66 therein, and the end portions of the connecting rods 65 and 65 are fixed to pistons provided inside the cylinders 66 and 66. . Accordingly, when a predetermined pressure oil is supplied to the cylinders 66, 66, the nozzle 54 of the injection device 52 touches the snorkel 62 with a predetermined touch force. In the injection molding machine 64 described in Patent Document 2, when the mold is opened and closed, the injection device 52 slides integrally with the intermediate mold 57 and the nozzle 54 is maintained in a state of touching the snorkel 62. Therefore, it is possible to prevent air from entering the molten resin.

  Both the stack mold described in Patent Document 1 and the injection molding machine 64 to which the stack mold 51c described in Patent Document 2 is attached can prevent air from entering the mold and the molten resin when the mold is opened. However, there are also problems to be solved. For example, in the case of the stack mold described in Patent Document 1, there is a problem that the structure of the mold becomes complicated because a special valve must be provided in the manifold body 58. Further, there is a possibility that air is mixed into the scallop or the molten resin also from the fixed manifold 56 side, but no special measures are taken on the fixed manifold 56 side. If a valve is also provided on the fixed side manifold 56 side, it is possible to reliably prevent cracks and the like, but the structure of the mold becomes more complicated and the cost increases. Furthermore, since the connection / separation of the fixed side manifold 56 and the manifold main body 58 is repeated every time the mold is opened and closed, there is a problem that the connecting portion is worn out early. On the other hand, in the injection molding machine described in Patent Document 2, since the nozzle 54 is maintained in a state of touching the snorkel 62 even when the mold is opened and closed, it is possible to reliably prevent air from being mixed into the drool and the molten resin. However, the injection molding machine 64 must be provided with a through hole for allowing the connecting rod 65 to be inserted into the fixed platen 53, and the injection device 52 must be provided with a flange portion 67 having cylinders 66 and 66. I must. In other words, this stack mold 51c cannot be attached to a general-purpose injection molding machine, and there is a problem that a dedicated injection molding machine 64 must be prepared. Further, there is a problem that the injection device 52 does not move forward and backward autonomously. That is, the injection device 52 is pulled by the intermediate mold 57 by the connecting rods 65, 65, etc., and slides on the bed B. A large inertia force acts on the injection device 52 due to its mass. 57 needs to pull the injection device 52 against this inertial force. Then, a large load is applied to the rack and pinion mechanism 61 that drives the intermediate mold 57, causing a failure. Alternatively, a large rack and pinion mechanism 61 must be prepared to withstand this load, resulting in high costs.

  An object of the present invention is to provide an operation method of an injection molding machine to which a predetermined stack mold is attached, which solves the above-described problems. Specifically, the structure of the stack mold is complicated. Provided with an injection molding machine operation method that can be carried out even with a general-purpose injection molding machine without any need, and can reliably prevent air from entering the scallop or molten resin despite its low cost. The purpose is to do.

  In order to achieve the above object, the present invention is configured as an operating method of an injection molding machine to which a stack mold having a predetermined structure is attached. The stack mold is composed of a fixed mold attached to the fixed platen, a movable mold attached to the movable platen, and an intermediate mold provided between these molds. The intermediate mold is provided with a fixed-length snorkel in order to guide the molten resin injected from the intermediate mold to the intermediate mold. This snorkel is inserted through a through-hole formed in the fixed mold, and advances and retreats according to opening and closing of the mold. In an injection molding machine to which such a stack mold is attached, the nozzle of the injection device is made to touch the snorkel with a predetermined touch force. When opening and closing the mold, the injection device is driven back and forth so that the touch force is maintained within a predetermined range. Then, even when the mold is opened and closed, the nozzle can be kept touching the snorkel.

Thus, the invention described in claim 1 is a control method at the time of mold opening and closing in an injection molding machine comprising a mold clamping device and an injection device, and a predetermined stack mold attached to the mold clamping device, the stack mold Is a fixed-side mold attached to the fixed platen, a movable-side die attached to the movable platen, and an intermediate die provided between the fixed-side die and the movable-side die. The intermediate mold is provided with a fixed-length snorkel that guides the molten resin injected from the injection device to the intermediate mold, and the snorkel is inserted into a through-hole opened in the fixed-side mold. The injection device is configured to advance and retreat according to mold opening / closing, and when the nozzle touches the snorkel with a predetermined touch force and drives the mold clamping device to open / close the mold, the touch force Is prescribed Driving the injection device so as to be maintained in the range back and forth, thereby configured as an operation method of an injection molding machine, characterized by maintaining in a state of touching the nozzle in the mold opening and closing.
According to a second aspect of the present invention, in the operation method according to the first aspect, the fixed side mold, the intermediate mold, and the movable side mold are connected to each other by a predetermined connection mechanism, and the mold is opened and closed to When the movable mold is moved forward and backward with respect to the fixed mold, the intermediate mold is moved forward and backward by the connecting mechanism, and the mold clamping device is configured to open and close the intermediate mold when opening and closing the mold. It is configured as an operation method of an injection molding machine, characterized in that driving is performed so that the advance speed becomes substantially constant.
According to a third aspect of the present invention, in the operation method according to the first or second aspect of the present invention, the injection device is driven in the front-rear direction by a servo motor. .
According to a fourth aspect of the present invention, in the driving method according to any one of the first to third aspects, the touch force for maintaining the touched state when the mold is opened and closed is more than the touch force at the time of injection. The operation method of the injection molding machine is characterized by a small force.

  As described above, the present invention is configured as a control method at the time of opening and closing a mold in an injection molding machine that includes a mold clamping device and an injection device, and a predetermined stack mold is attached to the mold clamping device. The stack mold includes a fixed mold attached to the stationary platen, a movable mold attached to the movable platen, and an intermediate mold provided between the fixed mold and the movable mold. The intermediate mold is provided with a fixed-length snorkel that guides the molten resin injected from the injection device to the intermediate mold, and the snorkel is inserted into a through-hole opened in the fixed mold to open and close the mold. It is designed to move forward and backward accordingly. In the operation method of the present invention, when the injection device causes the nozzle to touch the snorkel with a predetermined touch force and the mold clamping device is driven to open and close the mold, the touch force is maintained within a predetermined range. Thus, the injection device is driven back and forth so that the nozzle is kept touched during mold opening and closing. Therefore, the nozzle is not separated from the snorkel when the mold is opened, and the resin passage is not cut, so that air entrainment in the scallop or the molten resin can be reliably prevented. In addition, the stack mold only needs to provide a fixed-length snorkel in the intermediate mold, and no particularly complicated structure is required. In other words, it can be implemented at low cost and there is no connection structure, so there is no worry about wear. The injection molding machine need not be a dedicated machine and can be implemented by a general-purpose machine. Furthermore, what is carried out in order to keep the nozzle touched when the mold is opened and closed is to drive the injection device back and forth. That is, the injection device is actively driven. In this case, the intermediate mold does not need to pull the heavy injection device, and the intermediate mold is not burdened. According to another invention, the fixed mold, the intermediate mold, and the movable mold are connected to each other by a predetermined connecting mechanism, and when the mold is opened and closed, the movable mold is moved forward and backward with respect to the fixed mold. The intermediate mold is moved forward and backward by the coupling mechanism, and the mold clamping device is configured to be driven so that the forward and backward speed of the intermediate mold is substantially constant when the mold is opened and closed. Yes. As described above, when the forward / backward speed of the intermediate mold is made constant, the forward / backward speed of the snorkel becomes constant. In this case, in order to maintain the state in which the nozzle is touched, the injection device is also driven at a substantially constant speed, and therefore, the acceleration is hardly generated in the injection device during that time. As a result, the disturbance is reduced, so that the driving of the injection device can be easily controlled. According to another invention, the injection device is driven back and forth by the servo motor, so that the injection device can be driven accurately. According to yet another invention, the touch force for maintaining the touched state when the mold is opened and closed is configured to be smaller than the touch force at the time of injection, so It is only necessary to maintain a minimum touch force to prevent mixing, and it is not necessary to apply a touch force necessary for injection. If it does so, the load with respect to an injection device or a stack mold can also be made small.

It is a front view of the injection molding machine with which the stack mold which concerns on embodiment of this invention is attached. It is a graph explaining the driving | running method in the injection molding machine with which the stack mold which concerns on embodiment of this invention is attached, The (a) is a graph which shows the speed | velocity | rate of the movable platen during intermediate | middle mold opening and closing, and an intermediate mold (A) is a graph showing the change in the touch force of the nozzle of the injection device in the injection molding cycle. It is a figure which shows a prior art example, The (a), (b) is a front view which shows a different kind of stack mold, The (c) is the front which shows the injection molding machine to which the predetermined kind of stack mold is attached. FIG.

  Hereinafter, this embodiment will be described. As shown in FIG. 1, the injection molding machine 1 according to the present embodiment is provided with a stack mold 2 having a predetermined structure. The injection molding machine is almost the same as a conventional toggle type injection molding machine. It is constituted similarly. That is, the injection molding machine 1 includes a mold clamping device 3 driven by a toggle mechanism and an injection device 4. The mold clamping device 3 is guided by a fixed plate 6, a mold clamping housing 7, four tie bars 8, 8,... The movable platen 10 is opened and closed, and the toggle mechanism 11 is provided between the mold clamping housing 7 and the movable platen 10. In the present embodiment, the toggle mechanism 11 is driven when the cross head 15 is driven by a mold opening / closing servo motor 12 and a ball screw mechanism 13. The injection device 4 includes a heating cylinder 16 and a screw 17 (not shown) that is driven in the rotation direction and the injection direction within the heating cylinder 16. It is provided above. The injection device 4 provided on the table 17 is driven in the front-rear direction by the following injection device driving means 19. That is, the injection device driving means 19 is provided on one side with a ball screw 21 fixed to the fixed plate 6, a ball nut 22 screwed into the ball screw 21, and the base 17, and rotationally drives the ball nut 22. Servo motor 24 and the like. A predetermined support member 25 is fixed to the base 17, and the support member 25 is connected to the servo motor 24 by a spring body 26. That is, in the injection device driving means 19, when the servo motor 24 is driven to rotate the ball nut 22, the ball nut 22 and the servo motor 24 are driven back and forth, and the support member 25 and the injection device 4 are driven via the spring body 26. It will be. A touch force of the nozzle 28 described later is generated according to the compression amount of the spring body 26. The ejection device driving means 19 is provided with a touch force sensor 29 for detecting the compression amount of the spring body 26, that is, the touch force. In the present embodiment, the injection device driving means 19 is driven not by the geared motor but by the servo motor 24, so that it can be controlled accurately.

  The stack mold 2 according to the present embodiment is provided between a stationary die 31 attached to the stationary platen 6, a movable die 32 attached to the movable platen 10, and the gap therebetween. The intermediate mold 33 and a rack and pinion mechanism 35 that interconnects these molds 31, 32, and 33 are configured. In the rack and pinion mechanism 35, one rack 36 is provided in the fixed mold 31 and the other rack 37 is provided in the movable mold 32, and a pinion 38 is provided between the racks 36 and 37, and the pinion The shaft 38 is rotatably supported with respect to the intermediate mold 33. Therefore, when the mold clamping device 3 is driven to open and close the mold, and the movable side mold 32 is driven back and forth with respect to the fixed side mold 31, the movement amount is ½ of the movable side mold 32. The intermediate mold 33 is driven back and forth. 1, the intermediate mold 33 is shown as being supported only by the rack and pinion mechanism 35. However, the intermediate mold 33 may be slidably passed through the tie bars 8, 8,. . In the stack mold 2, the intermediate mold 33 is provided with a fixed-length snorkel 40 having a resin passage formed therein, and is connected to a manifold 41 in the intermediate mold 33. The snorkel 40 is inserted into a through-hole opened in the fixed-side mold 31, and when the stack mold 2 is opened and closed, the snorkel 40 moves to the left and right in the drawing together with the intermediate mold 33. In the present embodiment, the snorkel 40 is formed so that its end protrudes from the back surface of the fixed-side mold 31 by a predetermined length even when the mold is opened. You may form so that it may become the same position as the back surface of. When the stack mold 2 according to the present embodiment configured as described above is clamped, between the fixed mold 31 and the intermediate mold 33 and between the intermediate mold 33 and the movable mold 32. A cavity is formed in each. The molten resin injected from the injection device 4 is supplied to the manifold 41 via the snorkel 40 and branched in the manifold 41 to fill these cavities.

  A method for operating the injection molding machine according to the present embodiment will be described. First, the nozzle 28 of the injection device 4 is touched to the snorkel 40 prior to operation. The servo motor 24 of the injection device driving means 19 is driven to drive the injection device 4. The servomotor 24 is feedback-controlled so that the nozzle 28 touches the snorkel 40 and maintains a predetermined touch force. This touch force may be smaller than the touch force required at the time of injection. In other words, the touch force is such that air is not trapped from the nozzle 28 to the dripping or molten resin.

  In the operation method according to the present embodiment, when the mold clamping device 3 is driven to open and close the mold, the servo motor 24 is driven so as to keep the nozzle 28 touching the snorkel 40 to move the injection device 4 back and forth. Advance. Specifically, the servo motor 24 is controlled so that the touch force detected by the touch force sensor 29 falls within a predetermined range during mold opening / closing. Alternatively, the servo motor 24 is feedback controlled by applying a predetermined touch force as a target value. When the mold opening / closing servomotor 12 is driven at a constant speed, the mold clamping device 3 driven by the toggle mechanism 11 responds to the position of the movable platen as shown by the graph of reference numeral 42 in FIG. Moving plate speed changes. Then, the intermediate mold 33 and the snorkel 40 move while changing at a half speed as indicated by the graph of reference numeral 43. Thus, when the intermediate mold 33 and the snorkel 40 move forward and backward, the touch force sensor 29 detects a change in touch force. For example, when the mold is closed, the touch force varies as indicated by the graph denoted by reference numeral 44 in FIG. The servo motor 24 is controlled so that the touch force falls within a predetermined range. Alternatively, the servo motor 24 is controlled so that the target touch force 45 is obtained. As a result, the injection device 4 is retracted at substantially the same speed as the intermediate mold 33, and the nozzle 28 is maintained in a state in which the snorkel 40 is touched. In this way, entrainment of air into the rape and molten resin is prevented.

  When the mold clamping is completed, the servo motor 24 of the injection device driving means 19 is driven to generate a touch force required at the time of injection holding, as indicated by reference numeral 46 in FIG. As is conventionally known, molten resin is injected from the injection device 4. After holding the pressure for a predetermined time, the servo motor 24 is driven to reduce the touch force to the target touch force 45. The mold clamping device 3 is driven to open the mold. When the mold is opened, the touch force fluctuates in the same manner as when the mold is closed, but the servo motor 24 is controlled so that the touch force falls within a predetermined range. Alternatively, the servo motor 24 is controlled so that the target touch force 45 is obtained. Then, as a result, the injection device 4 moves forward at substantially the same speed as the intermediate mold 33, and the nozzle 28 is maintained in a state where it touches the snorkel 40. In this way, entrainment of air into the rape and molten resin is prevented.

  In the above operation method, the speeds of the intermediate mold 33 and the snorkel 40 change as shown in the graph of reference numeral 43 in FIG. Since the speed is thus changed, there is a slight disturbance in the control of the servo motor 24 of the injection device driving means 19. On the other hand, if the speeds of the intermediate mold 33 and the snorkel 40 in the mold opening and closing are controlled to be constant, the control of the servo motor 24 of the injection device driving means 19 becomes easier. In order to make the speed of the intermediate mold 33 and the snorkel 40 constant when the mold is opened and closed, control is performed so that the speed of the movable platen 10 becomes constant as shown by the graph 47 in FIG. For example, the position of the movable platen 10 may be detected and the mold opening / closing servomotor 12 may be controlled so that the speed is constant. Then, the intermediate mold 33 and the snorkel 40 are driven at a constant speed that is ½ of the speed of the movable platen 10, as indicated by a graph 48. When the mold clamping device 3 is controlled in this way, the servo motor 24 of the injection device driving means 19 can be easily controlled, and the nozzle 28 can be reliably kept touching the snorkel 40 even when the mold is opened and closed. It is possible to prevent air from being entrained in the molten resin.

DESCRIPTION OF SYMBOLS 1 Injection molding machine 2 Stack mold 3 Clamping device 4 Injection device 6 Fixed platen 7 Clamping housing 8 Tie bar 10 Movable platen 11 Toggle mechanism 12 Mold opening / closing servo motor 15 Crosshead 19 Injection device drive means 21 Ball screw 22 Ball nut 24 Servo Motor 26 Spring body 28 Nozzle 29 Touch force sensor 31 Fixed mold 32 Movable mold 33 Intermediate mold 35 Rack and pinion mechanism 40 Snorkel 41 Manifold

Claims (4)

A control method at the time of opening and closing a mold in an injection molding machine comprising a mold clamping device and an injection device, wherein a predetermined stack mold is attached to the mold clamping device,
The stack mold includes a fixed mold attached to the fixed platen, a movable mold attached to the movable platen, and an intermediate portion provided between the fixed mold and the movable mold. The intermediate mold is provided with a fixed-length snorkel that guides the molten resin injected from the injection device to the intermediate mold, and the snorkel is a through-hole opened in the fixed-side mold. Is inserted and moved forward and backward according to the mold opening and closing,
The injection device causes the nozzle to touch the snorkel with a predetermined touch force, and when the mold clamping device is driven to open and close the mold, the injection device is maintained in a predetermined range. Is driven back and forth, thereby maintaining the nozzle touched during mold opening and closing. The operation method according to claim 1, wherein the fixed-side mold, the intermediate mold, and the movable-side mold are connected to each other by a predetermined connection mechanism, and are opened and closed to move the movable mold relative to the fixed-side mold. When the side mold is moved forward and backward, the intermediate mold is moved forward and backward by the connecting mechanism,
The method of operating an injection molding machine, wherein the mold clamping device is driven so that a forward / reverse speed of the intermediate mold is substantially constant when the mold is opened and closed.   3. The operation method according to claim 1, wherein the injection device is driven back and forth by a servo motor.   The driving method according to any one of claims 1 to 3, wherein the touch force for maintaining the touched state when the mold is opened and closed is smaller than the touch force at the time of injection. Operation method of injection molding machine.

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