JP4443373B2 - Injection molding machine - Google Patents

Description

  The present invention relates to an in-line screw type injection molding machine in which sucking back is performed by retracting a screw after completion of measurement.

  In an in-line screw type injection molding machine with a screw that can be rotated and moved back and forth in a heating cylinder, the resin material is plasticized and kneaded by rotating the screw, and the molten resin is fed to the tip of the screw and stored. The molten resin stored on the tip end side of the screw by the advancement of the screw is injected and filled into the mold. In the weighing operation in which the molten resin is stored on the screw tip side by rotating the screw, the pressure is applied to the stored molten resin. Prone to occur. This resin leak is a phenomenon that occurs even in an in-line screw type horizontal injection molding machine in which the plasticization / injection system mechanism is arranged horizontally. In particular, the plasticization / injection system mechanism (plasticization / injection unit) is located above the mold. In an in-line screw type vertical injection molding machine that is configured to inject and fill molten resin from the nozzle at the tip of the heating cylinder into the mold from the top to the bottom, due to the influence of gravity, The resin leakage becomes remarkable.

  In order to prevent the above resin leakage, there is also a method using a bubble nozzle with a valve attached to the nozzle tip, but if the valve nozzle is adopted, the structure becomes complicated and a drive source dedicated to the valve at the nozzle tip is also required, In general, after the completion of the metering operation, the screw is retracted by a predetermined amount to reduce the pressure of the molten resin for one shot stored at the tip of the screw. I try to do it. Such a suck-back operation is generally known in an in-line screw type injection molding machine.

  In the injection molding machine, if the nozzle repetition mode in which the nozzle back / touch is performed for each molding cycle is taken, one cycle time is extended. Therefore, in general, the nozzle touch state (the tip of the nozzle is in the resin injection port of the mold) It is designed to perform continuous automatic operation in the pressed state. During the continuous automatic operation, the weighing and suck back are generally completed before the molded product is projected.

  FIG. 4 is a diagram showing each step in one molding cycle of continuous automatic operation along the time axis. As shown in the figure, as soon as the injection process (primary injection process and pressure holding process) is completed, the cooling timer works (starts), and the metering starts simultaneously with the start of the cooling timer, and within the cooling period. The weighing process and the subsequent suckback process are completed (before the cooling timer expires).

  Therefore, the resin is clogged in the mold during the metering operation, and the molten resin does not enter the mold from the nozzle tip during the metering operation. In addition, after the sackback is completed, the pressure of the molten resin stored on the tip side of the screw is reduced, and the time from the completion of the sackback to the next injection filling is very short. There is almost no resin leakage into the mold.

  By the way, when exchanging dies after continuous automatic operation, the continuous automatic operation is stopped at the end timing (eject ejection end timing) of the eject operation (eject ejection / eject return), which is the break of one molding cycle. After this, the nozzle back operation is performed. As described above, the weighing and suck back are completed before the eject operation. For this reason, if the plasticizing / injecting system mechanism (plasticizing / injecting unit) is moved backward to perform the nozzle back operation (the operation of separating the nozzle tip from the mold), the amount of suck back during continuous automatic operation is reduced. Nozzle back will be performed as it is (the amount of suck back is not enough to take the nozzle back state), and after a certain amount of time, drooling that dripping the molten resin from the tip of the nozzle will occur In particular, this is remarkable in an in-line screw type vertical injection molding machine. When drooling occurs, in a vertical injection molding machine, the resin that has dropped from the tip of the nozzle falls near the resin inlet of the mold and solidifies. The current situation is that the operator handles the drooling by placing a pan or the like under the nozzle by hand. Therefore, it has been pointed out that the operator is burdened when shifting from the nozzle touch state to the nozzle back state. Also, in a horizontal injection molding machine, it is inevitable that drooling will occur to some extent, and it has been unavoidable to wipe off the resin dripped by the drooling or the resin dripping from the nozzle tip side.

  The present invention has been made in view of the above points. The purpose of the present invention is to stop a continuous automatic operation in a nozzle touch state in an in-line screw type injection molding machine, and then shift to a nozzle back state. It is also possible to automatically prevent drooling from occurring.

In order to achieve the above-mentioned object, the present invention has a screw disposed in a heating cylinder so as to be able to rotate and move forward and backward, and is controlled by a controller that controls the operation of the machine. injection step, metering step, suck-back step, the mold opening process and eject steps of the injection molding machine of in-line screw type repeating in this order, said controller forming a final molding cycle being executed is preset continuous automatic operation When recognizing that it is a cycle, and executes a control of not performing our Keru metering process and suck-back process to the final molding cycle.

  According to the present invention, when recognizing that it is the final molding cycle of continuous automatic operation, the controller controls the metering operation and the suckback operation not to be performed in the final molding cycle. In the molding cycle, molten resin is not stored on the screw tip side. Therefore, no drooling occurs even if the nozzle back state is subsequently changed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a main configuration of an in-line screw type vertical injection molding machine according to an embodiment of the present invention (hereinafter referred to as the present embodiment). In this embodiment, application to a vertical injection molding machine is taken as an example, but the present invention can also be applied to an inline screw type horizontal injection molding machine.

  In FIG. 1, 1 is a fixed die plate of the mold opening / closing system mechanism, 1a is a central opening of the fixed die plate 1, 2 is a fixed mold attached to the fixed die plate 1, and 2a is a resin injection of the fixed mold 2. Inlet 3 is a vertically arranged inline screw type plasticizing / injecting unit, 4 is a lower holding plate, 5 is an upper holding plate, and 6 is spanned between the lower holding plate 4 and the upper holding plate 5. The guide shaft 7 has a base end attached to the lower holding plate 4 and a heating cylinder holding a nozzle 8 at its tip, and 9 rotates and moves back and forth in the heating cylinder 7 (moves linearly in the vertical direction). ) The screw 10 is arranged so as to be movable, 10 is a movable body that can move back and forth (moves linearly in the vertical direction) along the guide shaft, and 11 is rotatably held by the movable body 10, and the base of the screw 9 Pulley body holding the end, 12 A measuring servo motor mounted on the moving body 10 and rotationally driving the pulley body 11 (screw 9) via a driving pulley 13 and a timing belt (not shown); 14 is a ball screw mechanism for converting rotational motion into linear motion; 14a Is a nut body of a ball screw mechanism 14 whose end is fixed to the moving body 10, 14 b is a screw shaft of the ball screw mechanism 14 that is screwed into the nut body 14 a and is rotatably held by the upper holding plate 5, 15 The pulley 16 fixed to the screw shaft 14 b is mounted on the upper holding plate 5, and the pulley 15 is driven to rotate via the drive pulley 17 and a timing belt (not shown), thereby moving the moving body 10 via the ball screw mechanism 14. An injection servomotor for linearly moving the (screw 9), 18 is a support shaft having one end fixed to the fixed die plate 1, and 19 is a lower holding motor. A pulley / nut body 20, which is rotatably held by the panel 4 and screwed to the threaded portion 18 a of the support shaft 18, is mounted on the lower holding board 4, and the pulley / nut body 19 is connected to the drive pulley 21 and The pulley / nut body 19 is linearly moved along the threaded portion 18a of the support shaft 18 by being rotationally driven through a timing belt (not shown), whereby the entire plasticizing / injecting unit 3 is moved forward and backward (vertical direction). It is a servo motor for nozzle touch / back that is moved linearly.

  In addition, 31 is a servo driver that drives and controls the metering servo motor 12, 32 is a servo driver that drives and controls the injection servo motor 16, 33 is a servo driver that drives and controls the nozzle touch / back servo motor 20, and 34 is Controls overall control of the machine (injection molding machine), based on various programs given in advance and various preset values of each process, measurement information and time information from various sensors installed in each part of the machine These are controllers that drive and control various driver units such as the servo drivers 31 to 33.

  In the setting condition storage section of the memory 34a of the controller 34, there are set operation condition values for each process of mold clamping, mold opening, ejection, injection, weighing, suck back, control condition values for nozzle touch, nozzle back, and the like. Stored rewritable. The setting condition storage section of the memory 34a also stores operation control conditions used only for the final molding cycle of continuous automatic operation.

  In the configuration shown in FIG. 1, when the nozzle back operation is performed from the nozzle touch state in which the nozzle 8 at the tip of the heating cylinder 7 is pressed against the resin injection port 2 a of the fixed mold 2, the controller is operated based on an operator instruction or the like. 34 rotates the nozzle touch / back servomotor 20 through a servo driver 33 in a predetermined direction by a predetermined amount, and this rotational force is applied to a pulley / nut via a driving pulley 21 → a timing belt (not shown). Is transmitted to the body 19, and the pulley / nut body 19 is rotated in a predetermined direction, whereby the rotational motion is converted into a linear motion by a ball screw mechanism constituted by the pulley / nut body 19 and the screw portion 18a of the support shaft 18. The pulley / nut body 19 of the ball screw mechanism is then retracted (retracted and raised) by a predetermined amount. As a result, the plasticizing / injecting unit 3 is retreated (retreated and raised) by a predetermined amount, and the nozzle 8 is shifted to a nozzle back state in which the nozzle 8 is sufficiently removed from the central opening 1 a of the fixed die plate 1.

  When performing the nozzle touch operation from the nozzle back state described above, the controller 34 rotates the nozzle touch / back servo motor 20 by a predetermined amount in the direction opposite to the previous direction via the servo driver 33 based on an operator instruction or the like. Driving, this rotational force is transmitted to the pulley / nut body 19 via the driving pulley 21 → the timing belt (not shown), and the pulley / nut body 19 is rotated in the opposite direction, thereby A rotary motion is converted into a linear motion by a ball screw mechanism constituted by the pulley / nut body 19 and the screw portion 18a of the support shaft 18, and the pulley / nut body 19 of the ball screw mechanism is advanced (advanced and lowered) by a predetermined amount. As a result, the plasticizing / injecting unit 3 is advanced (advanced and lowered) by a predetermined amount, and the nozzle 8 is shifted to the nozzle touch state pressed against the resin injection port 2a of the fixed mold 2. . In the continuous automatic operation mode, this nozzle touch state is taken, and each operation of weighing, sucking back, and injection performed in the nozzle touch state is performed as follows.

  First, at the time of the weighing process, the controller 34 drives the measuring servo motor 12 to rotate in a predetermined direction via the servo driver 31, and this rotational force is transmitted via the driving pulley 13 → the timing belt (not shown) → the pulley body 11. Then, the screw 9 is rotated in a predetermined direction and transmitted to the screw 9 to knead and plasticize the resin raw material supplied to the base end side of the heating cylinder 7, while the screw 9 feeds the screw 9 to the screw tip side. To send. Then, as the molten resin is stored on the screw tip side, the screw 9 controls the back pressure (this is a force transmission described later by the drive control of the injection servo motor 16 by the servo driver 32 based on the instruction of the controller 34. The controller 34 stops the metering servo motor 12 when a predetermined amount of molten resin is stored on the screw tip side while being retracted while being executed by pressure control on the screw 9 via the system. (The rotation of the screw 9 is stopped).

  In the suck-back process subsequent to the weighing process, the controller 34 drives the injection servo motor 16 to rotate in a predetermined direction via the servo driver 32, and this rotational force is applied to the driving pulley 17 → not shown timing belt → pulley. 15 is transmitted to the screw shaft 14b of the ball screw mechanism 14 to rotate the screw shaft 14b in a predetermined direction, whereby the ball screw mechanism 14 converts the rotational motion into a linear motion and the nut body of the ball screw mechanism 14 14a is retracted (retracted and raised), together with the nut body 14a, the movable body 10 and each member (such as the screw 9) that moves back and forth integrally with the nut 10a are retracted (retracted and raised) by a predetermined amount. By retreating, the pressure of the molten resin stored on the screw tip side is reduced.

  In the injection process, the controller 34 rotationally drives the injection servo motor 16 by speed feedback control in the direction opposite to the suck back process via the servo driver 32, and this rotational force is driven by the drive pulley 17 → not shown. The belt is transmitted to the screw shaft 14b of the ball screw mechanism 14 via the pulley 15 to rotate the screw shaft 14b in the direction opposite to the suck back process, and thereby, the ball screw mechanism 14 converts the rotational motion into a linear motion. Then, the nut body 14a of the ball screw mechanism 14 is rapidly advanced (advanced and lowered), and together with the nut body 14a, the moving body 10 and each member (such as the screw 9) that moves forward and backward integrally are rapidly advanced (screw 9). The molten resin stored on the screw tip side by the rapid advance of the screw is moved to the fixed mold 2 and The Shimese unexpected cavity formed by the movable side mold (molding space), so as to inject and fill. Thereafter, the controller 34 drives the injection servo motor 16 by pressure feedback control, and thereby holds the pressure in the resin in the mold through a resin called a cushion amount slightly remaining at the tip of the screw 9. Is applied.

In the present embodiment, when recognizing that the controller 3 4 themselves is the final molding cycle of continuous automatic operation, in the final molding cycle, and controls so as not to perform metering operations and suck-back operation. Therefore, in the final molding cycle, the molten resin is not stored on the screw tip side, so that no drooling occurs even if the nozzle back state is subsequently entered.

The condition that the controller 34 recognizes as the final molding cycle of continuous automatic operation is a molding cycle corresponding to the final shot of a preset number of shots by cumulatively calculating the number of shots (number of molding cycles). and this determines that, and the like.

  FIG. 2 is a diagram showing a control processing flow by the controller 34 of the present embodiment. First, in step 1, it is determined whether or not the next molding cycle is the final molding cycle of continuous automatic operation. If the determination is NO, the process proceeds to step S2. If the determination is YES, the process proceeds to step S3. In step S2, one molding cycle is controlled under the normal molding cycle control conditions (that is, under the control conditions such that each process shown in FIG. 4 is executed), and the process returns to step S1. In step S3, one molding cycle is controlled under the final molding cycle control conditions, that is, under the control conditions in which the metering operation and the suck-back operation are not performed, and the process proceeds to step S4. In step S4, the continuous automatic operation is stopped and this processing flow is ended. FIG. 3 shows each step of one molding cycle executed in step S3 along the time axis.

  In addition, when it is the operation condition setting which performs nozzle back immediately after completion | finish of continuous automatic driving | operation, after ending continuous automatic driving | operation, the controller 34 performs nozzle back operation | movement, and complete | finishes continuous automatic driving | operation. Later, when the operation for setting the nozzle back is performed when an operation for instructing the shift to the manual operation mode is performed by the operator, the controller 34 at the timing when the operator instructs the shift to the manual operation mode. The nozzle back operation is executed.

It is explanatory drawing which shows the principal part structure of the vertical injection molding machine which concerns on one Embodiment of this invention. It is a flowchart which shows the control processing flow by the controller of the vertical injection molding machine which concerns on one Embodiment of this invention. It is explanatory drawing which shows each process in the last molding cycle of continuous automatic operation | movement controlled by the controller of the vertical injection molding machine which concerns on one Embodiment of this invention along a time-axis. It is explanatory drawing which shows each process in 1 molding cycle of the continuous automatic operation in an injection molding machine along a time axis.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixed die plate 1a Center opening 2 Fixed side metal mold | die 2a Resin injection port 3 Plasticization / injection unit 4 Lower holding board 5 Upper holding board 6 Guide shaft 7 Heating cylinder 8 Nozzle 9 Screw 10 Moving body 11 Pulley body 12 For measurement Servo motor 13 Drive pulley 14 Ball screw mechanism 14a Nut body 14b Screw shaft 15 Pulley 16 Injection servo motor 17 Drive pulley 18 Support shaft 18a Screw portion 19 Pulley / nut body 20 Nozzle touch / back servo motor 21 Drive pulley 31, 32, 33 Servo driver 34 Controller 34a Memory

Claims (1)

It has a screw that can be rotated and moved back and forth in the heating cylinder and is controlled by the controller that controls the operation of the machine. During continuous automatic operation, the mold clamping process, injection process, weighing process, suck back process, mold In an inline screw type injection molding machine that repeats the opening process and the ejecting process in this order ,
The controller, upon recognizing that the molding cycle being executed is the final molding cycle of continuous automatic operation which is set in advance, performs a control not to perform our Keru metering process and suck-back process to the final molding cycle An injection molding machine characterized by that.

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