JP2009006525A - Pre-plastic injection molding equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a preplasticization injection molding machine which can surely prevent the backflow of a molten resin retained in an injection cylinder to a plastication cylinder and can prevent the occurrence of drooling. <P>SOLUTION: The preplasticization injection molding machine has a plastication part 1 equipped with the plastication cylinder 11 and a plastication screw 12, an injection part 2 which retains the molten resin 7 supplied from the plastication cylinder 11 in the injection cylinder 21 and injects/packs the retained molten resin 7 in a mold 3 by an injection plunger 22, and a mold clamping device 4 for clamping the mold 3. A supply route 24 making a retention space 20 for the molten resin 7 in the injection cylinder 21 and the plastication cylinder 11 communicate with each other is formed. A valve 28, which is installed forward/backward movably in the retention space 20, closes a communication opening to an injection nozzle 6 and a communication opening to the supply route 24 when moved forward, and opens the communication opening to the injection nozzle 6 and the communication opening to the supply route 24 when moved backward is installed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pre-plastic injection molding apparatus that supplies a molten resin melted by a plasticizing screw to an injection cylinder and injects the molten resin in the injection cylinder into a mold by an injection plunger.

  Conventionally, a pre-plastic injection molding apparatus is known (see, for example, Patent Document 1). For example, as shown in FIG. 4, the pre-plastic injection molding apparatus includes a mold 3, a plasticizing cylinder 11, a plasticizing portion 1 having a plasticizing screw 12 that is rotationally driven in the plasticizing cylinder 11, an injection cylinder 21, and an injection cylinder. The injection part 2 provided with the injection plunger 22 which can reciprocate within the cylinder 21 is provided. Hereinafter, one molding cycle of an injection molding method using a conventional pre-plastic injection molding apparatus will be described in order based on FIG.

  The pre-plastic injection molding apparatus shown in FIG. 4 (a) shows a state during the mold clamping process. In this mold clamping step, the mold 3 is clamped, and a predetermined amount of molten resin 7 supplied from the plasticizing cylinder 11 via the supply path 24 is waited in a state where it is stored in the injection cylinder 21. Yes, after this mold clamping process, the process proceeds to the injection process. In the injection process, as shown in FIG. 4B, the injection plunger 22 is moved forward, whereby the molten resin 7 in the injection cylinder 21 is injected into the mold 3 through the injection nozzle 6 provided at the tip of the injection cylinder 21. Fill. The injection plunger 22 pushes out the molten resin 7 stored in the injection cylinder 21 without leakage. Next, the molding process and the metering process are started simultaneously. In the molding step, as shown in FIG. 4C, cooling and hardening of the molten resin 7 injected into the mold 3 is started. In the metering process started simultaneously with the molding process, the plasticizing screw 12 is rotated as shown in FIGS. 4C and 4D, thereby plasticizing the resin material such as resin pellets supplied from the hopper 14. At the same time, the molten resin 7 in the plasticizing cylinder 11 is melted by the shearing force accompanying the rotation of the screw 12 and fed into the front end portion of the injection cylinder 21 through the supply path 24, thereby causing the injection plunger 22 to retreat, The molten resin 7 measured to a predetermined volume is filled in the front end portion of the injection cylinder 21. Then, after the measuring step and the forming step are completed, the mold 3 is opened as shown in FIG. 4E, and the take-out device 5 moves to a take-out step in which the solidified product 8 is taken out from the die 3. Thereafter, one molding cycle consisting of the above steps is repeatedly executed to obtain a large number of molded products 8.

  By the way, in the pre-plastic injection molding apparatus, the molten resin 7 in the plasticizing cylinder 11 is sent into the front end portion of the injection cylinder 21 through the supply path 24 in the measuring step. In the state where 24 is left open, there is a problem that the molten resin 7 stored in the injection cylinder 21 flows backward to the plasticizing cylinder 11.

In the state where the mold 3 is opened in the take-out process, the molten resin 7 in the injection cylinder 21 passes through the injection nozzle 6 provided at the front end of the injection cylinder 21 as shown in FIG. In this case, there is a problem that the leaked molten resin 7 becomes an obstacle when the mold 3 is closed, and the shift to the next process is hindered.
Japanese Patent Laid-Open No. 6-166072

  The present invention was invented in view of the above-mentioned conventional problems, and the object of the present invention is to reliably prevent the backflow of molten resin stored in the injection cylinder to the plasticizing cylinder and to drooling. An object of the present invention is to provide a pre-plastic injection molding apparatus capable of preventing the occurrence of the above.

  In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that the plasticizing part 1 including the plasticizing cylinder 11 and the plasticizing screw 12 and the molten resin 7 supplied from the plasticizing cylinder 11 are placed in the injection cylinder 21. In addition to storing, the injection part 2 for injecting and filling the stored molten resin 7 from the injection nozzle 6 provided at the front end of the injection cylinder 21 to the mold 3 by the injection plunger 22, and mold clamping for clamping the mold 3 A pre-plastic injection molding apparatus comprising a device 4, wherein a supply path 24 is provided to communicate the storage space 20 of the molten resin 7 in the injection cylinder 21 and the plasticizing cylinder 11, and the storage space of the injection cylinder 21 The communication port is disposed in the inside 20 so as to freely advance and retract, and closes the communication port to the injection nozzle 6 and the communication port to the supply path 24 when moving forward, and the communication port to the injection nozzle 6 when moving backward. It is made by providing a valve body 28 to open the communication port to the supply path 24 is characterized in.

  With such a configuration, it is possible to reliably prevent the backflow of the molten resin 7 stored in the injection cylinder 21 to the plasticizing cylinder 11 and to prevent the occurrence of drooling. It is possible.

  Further, the invention according to claim 2 is the invention according to claim 1, wherein in the injection cylinder 21, an advancing / retreating shaft portion 25 having a long rod shape in the front and rear direction is provided so as to be movable back and forth, and at the front end portion of the advancing / retreating shaft portion 25. The valve body 28 is fixed, the injection plunger 22 is formed in an annular shape, and is slidably fitted to the advance / retreat shaft portion 25.

  With such a configuration, the cross-sectional area of the storage space 20 is reduced, the volume of the storage space 20 per unit length in the axial direction of the injection cylinder 21 is reduced, and the molten resin 7 stored in the storage space 20 is reduced. This makes it possible to easily fine-tune the amount of storage and increase the resolution.

  The invention according to claim 3 is characterized in that, in the invention according to claim 2, the advance / retreat shaft portion 25 is selectively provided from a plurality of advance / retreat shaft portions 25 having different diameters.

  With such a configuration, it is possible to change the cross-sectional area of the storage space 20 simply by replacing the advance / retreat shaft portion 25 with the advance / retreat shaft portion 25 having a different diameter.

  In the pre-plastic injection molding device of the present invention, in the metering step, the valve body is advanced to close the communication port to the injection nozzle and to open the communication port to the supply path, thereby preventing drooling. In the injection process, the valve body is retracted to open the communication port to the injection nozzle and close the communication port to the supply path to prevent the molten resin from flowing back from the injection cylinder to the plasticizing cylinder. Is something that can be done.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  As shown in FIG. 1, the pre-plastic injection molding apparatus includes a mold 3, a mold clamping device 4 that opens and closes the mold 3, a take-out device 5 that takes out a molded product 8 from the mold 3 (see FIG. 2), A plasticizing part 1 for plasticizing and melting the resin material and an injection part 2 for injecting the plasticized and melted molten resin 7 into the mold 3 are provided. In the following description, the direction in which the injection nozzle 6 described later of the injection cylinder 21 is provided is referred to as the front side, and the base end side of the injection plunger 22 described later is referred to as the rear side on the side opposite to the direction where the injection nozzle 6 is provided.

  The plasticizing unit 1 includes a plasticizing cylinder 11 arranged in a posture inclined downward toward the front end side, a plasticizing screw 12 provided in the plasticizing cylinder 11, and a screw that rotates the plasticizing screw 12. And a drive unit 13. The plasticizing cylinder 11 is provided with a hopper 14, and the resin material stored in the hopper 14 is supplied into the plasticizing cylinder 11 through a material supply port 15 provided on the base end side of the plasticizing cylinder 11. It has become. The plasticizing screw 12 is driven to rotate about the axis by the screw driving unit 13 and the inside of the plasticizing cylinder 11 is heated by a cylinder heater (band heater) (not shown) provided on the outer periphery of the plasticizing cylinder 11. The resin material supplied into the plasticizing cylinder 11 through the material supply port 15 can be melted while being sent to the tip side by the shearing force accompanying the rotation of the plasticizing screw 12 and the heating of the cylinder heater 26.

  The injection unit 2 includes an injection cylinder 21 that is arranged side by side with respect to the plasticizing cylinder 11 in a horizontal posture, an injection plunger 22 that is installed in the injection cylinder 21 so as to be movable back and forth in the axial direction, and an injection plunger 22 that is an axis of the injection cylinder 21. A plunger driving unit 23 that drives in a direction, and a valve body 28 and an advancing / retreating shaft unit 25 described later according to the present invention are provided. The front end of the injection cylinder 21 is connected to the other end of the supply path 24, one end of which is connected to the tip of the plasticizing cylinder 11, so that the inside of the front end of the injection cylinder 21 is connected to the plasticizing cylinder. The inside of the front end portion of the injection cylinder 21 is a storage space 20 in which the molten resin 7 is stored. An injection nozzle 6 is provided at the center of the front end of the injection cylinder 21.

  The mold 3 includes a fixed mold 31 provided on a fixed plate 41 of the mold clamping device 4 and a movable mold 32. The mold 3 is disposed in front of the injection cylinder 21 and is movable relative to the fixed mold 31 by the mold clamping device 4. By moving 32, the mold 3 can be clamped and opened.

  The injection port 61 provided at the tip of the injection nozzle 6 communicates with the cavity of the mold 3 through the fixed platen 41. Then, by advancing the injection plunger 22 by the plunger drive unit 23, the molten resin 7 stored in the front end portion of the injection cylinder 21 is injected and filled into the mold 3 through the injection nozzle 6 provided at the front end of the injection plunger 22. It can be done.

  As shown in FIG. 3, the injection nozzle 6 is formed in a tapered shape so that the front end portion has a smaller flow path diameter toward the front side. The nozzle body is provided with heating means and cooling means, and when the molten resin 7 is injected and filled into the mold 3 through the injection nozzle 6, the temperature of the injection nozzle 6 is the same as the temperature of the molten resin 7. It controls to become.

  The screw drive unit 13, the plunger drive unit 23, the mold clamping device 4, the nozzle heating unit, the cooling unit, and the like are controlled by a control unit (not shown), whereby a series of molding cycles shown in FIGS. 1 (a) to 1 (e). Can be molded repeatedly.

  One molding cycle is performed in parallel with the mold clamping process, the injection process performed after the mold clamping process, the molding process performed after the injection process, the take-out process performed after the molding process, and the molding process. The weighing process is executed. Hereinafter, each process will be schematically described.

  In the mold clamping process, as shown in FIGS. 1A, 2A, and 2B, the mold 3 that is in the mold clamping state at the start of the mold clamping process is clamped by the mold clamping device 4 and plasticized. It waits in the state which filled the molten resin 7 supplied via the supply path 24 from the cylinder 11 in the front-end part of the injection cylinder 21, and stored it. In this mold clamping process, the plasticizing screw 12 and the injection plunger 22 are in a stopped state.

  In the injection process, the injection plunger 22 that is in the retracted position at the start of the injection process is advanced by the plunger drive unit 23 as shown in FIG. 1 (c), and as a result, inside the front end of the injection cylinder 21 as shown in FIG. 2 (c). The molten resin 7 stored in is injected and filled into the mold 3 in a mold-clamping state via the injection nozzle 6. At this time, the injection nozzle 6 is controlled to maintain the same temperature as that of the molten resin 7. When the filling of the molten resin 7 into the mold 3 is completed, the molding process is started.

  In the molding step, as shown in FIG. 1C, the molten resin 7 filled in the mold 3 in the injection step is cooled for a predetermined time until it is solidified. Then, when the predetermined time has elapsed and the cooling and hardening of the molten resin 7 in the mold 3 has been completed, the process proceeds to the removal step.

  The metering process is started at the same time as the molding process. In this metering process, as shown in FIGS. 1C and 1D, the plasticizing screw 12 is driven to rotate by the screw drive unit 13 and supplied from the hopper 14 by this. The resin material is melted by the heating by the cylinder heater 26 provided in the plasticizing cylinder 11 and the shearing force accompanying the rotation of the plasticizing screw 12. At the same time, the rotation of the plasticizing screw 12 causes the molten resin 7 in the plasticizing cylinder 11 to be fed into the front end of the injection cylinder 21 through the supply path 24 to retract the injection plunger 22. The molten resin 7 measured to a predetermined volume is filled and stored in the front end portion. That is, the injection plunger 22 is retracted only when the plasticizing screw 12 is rotating.

  This metering process is executed after the molding process is completed and before the take-out process is started as shown in FIG. 1E. When the mold is opened in the take-out process, the screw drive unit 13 The rotation of the plasticizing screw 12 is stopped, the backward movement of the injection plunger 22 is stopped, and the metering process is finished.

  In the take-out process, the mold 3 that is in a clamped state is opened at the start of the take-out process, and the molded product 8 is knocked out after the mold 3 is in the open state as shown in FIGS. 2 (d) to 2 (e). The molded product 8 is ejected from the movable mold 32 by 51 and taken out by the take-out device 5.

  Hereinafter, the valve body 28 of the present invention will be described. The valve body 28 opens and closes the supply path 24 connected to the storage space 20 at the front end portion of the injection cylinder 21 from the tip of the plasticizing cylinder 11, and the outer shape (contour) of the cross section is stored at the front end portion of the injection cylinder 21. The outer shape of the space 20 is substantially the same, and a communication passage 29 for communicating the space before and after the valve element 28 is formed by providing a groove on the side surface or a flow path inside.

  In this valve body 28, the advancing / retreating shaft portion 25 is retracted and the valve body 28 closes the communication port to the supply passage 24 to close the supply passage 24, and the advancing / retreating shaft portion 25 is advanced to advance the valve body 28. Thus, the supply path 24 is opened by preventing the communication port to the supply path 24 from being blocked. The front end surface of the valve body 28 is shaped along the front end surface of the inner surface of the injection cylinder 21, and when the valve body 28 is advanced through the injection cylinder 21 to the front end, the front end surface of the valve body 28 and the injection cylinder 21. The front end surface of the inner surface of the injection cylinder abuts without any gap, and the communication port to the injection nozzle 6 provided at the front end of the injection cylinder 21 is closed.

  The advancing / retreating shaft portion 25 has a long rod shape in front and rear, and in this embodiment, the cross-sectional shape is circular, the front end portion is connected and fixed to the valve body 28, and the rear end portion is a drive portion ( (Not shown) and can be moved forward and backward. An annular injection plunger 22 is slidably fitted on the outer surface of the advance / retreat shaft portion 25, and the injection plunger 22 can be freely advanced and retracted with respect to the advance / retreat shaft portion 25 by the plunger drive portion 23. The outer shape of the injection plunger 22 in the vertical cross section in the axial direction of the injection cylinder 21 is substantially the same as the outer shape of the cross section of the storage space 20, and the molten resin 7 in the storage space 20 can be pushed out without omission. The molten resin 7 in the storage space 20 pushed forward by the injection plunger 22 is pushed out to the front side of the valve body 28 through the communication passage 29 of the valve body 28.

  In the pre-plastic injection molding apparatus of the present invention, in the measuring step shown in FIG. 1 (d), the advance / retreat shaft portion 25 is advanced so that the front end face of the valve body 28 and the front end face of the inner face of the injection cylinder 21 are moved. The communication port to the injection nozzle 6 is closed without a gap and the supply path 24 is opened, and in this state, the molten resin 7 in the plasticizing cylinder 11 is passed through the supply path 24 to the front end of the injection cylinder 21. Generation of drooling can be prevented by sending it out to the storage space 20 in the section.

  Further, in the injection step shown in FIG. 1C, the advance / retreat shaft portion 25 is moved backward to form a gap between the front end surface of the valve body 28 and the front end surface of the inner surface of the injection cylinder 21, so that the valve body The space before and after 28 is communicated through the communication passage 29 so that the molten resin 7 can be injected from the injection nozzle 6, and the communication port to the supply passage 24 is closed by the valve body 28 to close the supply passage 24. In this state, the injection plunger 22 is advanced in this state, and the molten resin 7 in the injection cylinder 21 is injected into the mold 3 through the injection nozzle 6. At this time, the communication port to the supply path 24 is opened by the valve body 28. Since it is closed, it is possible to prevent the molten resin 7 from flowing back from the injection cylinder 21 to the plasticizing cylinder 11.

  Further, in the present embodiment, while waiting for a predetermined amount of molten resin 7 supplied from the plasticizing cylinder 11 to be stored in the injection cylinder 21 and injected by the injection plunger 22 in the next injection step, the injection is performed. It becomes possible to maintain the temperature of the molten resin 7 stored in the cylinder 21 uniformly. That is, when the storage space 20 has a cylindrical shape as in the prior art, a predetermined volume of the molten resin 7 supplied from the plasticizing cylinder 11 is stored in the injection cylinder 21 and is on standby. The molten resin 7 located near the inner wall surface of the injection cylinder 21 is radiated from the injection cylinder 21 and has a lower temperature than the molten resin 7 located in the center portion far from the inner wall surface of the injection cylinder 21, resulting in a large temperature difference. As a result, the temperature distribution of the molten resin 7 becomes non-uniform so that the injection at the time of injection filling in the mold 3 is uneven and the material of the molded product 8 becomes non-uniform. Therefore, by making the storage space 20 annular as in the present invention, the advance / retreat shaft portion 25 is located in a portion away from the inner wall surface of the injection cylinder 21, and the molten resin 7 is pushed away by the advance / retreat shaft portion 25. The molten resin 7 stored in the storage space 20 is present within a certain distance (the width of the ring) from the inner surface of the injection cylinder 21, and the temperature distribution of the molten resin 7 is uneven. It is possible to suppress unevenness of injection and non-uniformity of the material of the molded product 8 when the mold 3 is injected and filled. In addition, when the molten resin 7 is present within the predetermined distance from the inner surface of the injection cylinder 21, if the cross section of the storage space 20 is circular, the radius needs to be within the predetermined distance. Since the cross-sectional area of the storage space 20 is smaller than that of the storage space 20, the annular shape is superior in that the storage amount can be increased.

  Further, since the cross-sectional area of the storage space 20 is reduced, the volume of the storage space 20 per unit length in the axial direction of the injection cylinder 21 is reduced, and the amount of the molten resin 7 stored in the storage space 20 is finely adjusted. Thus, the resolution can be increased and the resolution can be increased.

  In addition, the advancing / retreating shaft portion 25 is selectively provided from a plurality of advancing / retreating shaft portions 25 having different diameters, so that the cross-sectional area of the storage space 20 can be simply replaced by the advancing / retreating shaft portion 25 having a different diameter. Can be changed.

  The valve body 28 provided with the communication passage 29 as described above also functions as a torpedo for kneading the molten resin 7.

One Embodiment of this invention is shown, (a)-(e) is explanatory drawing which shows one molding cycle in order. (A)-(f) is explanatory drawing which shows the shaping | molding process of the metal mold | die same as the above in order. It is a principal part expanded sectional view of the injection nozzle vicinity of a pre-plastic injection molding apparatus same as the above. A prior art example is shown, (a)-(e) is explanatory drawing which shows one molding cycle in order. It is explanatory drawing of the conventional drooling.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasticization part 11 Plasticization cylinder 12 Plasticization screw 2 Injection part 20 Storage space 21 Injection cylinder 22 Injection plunger 24 Supply path 28 Valve body 3 Mold | die 4 Clamping apparatus 5 Taking out apparatus 6 Injection nozzle 7 Molten resin

Claims (3)

  A plasticizing section having a plasticizing cylinder and a plasticizing screw, and a molten resin supplied from the plasticizing cylinder are stored in the injection cylinder, and the stored molten resin is provided at the front end of the injection cylinder by an injection plunger. A pre-plastic injection molding apparatus comprising: an injection part for injection and filling a mold from an injection nozzle; and a mold clamping device for clamping the mold, wherein a molten resin storage space in the injection cylinder and a plasticizing cylinder Is provided in the storage space of the injection cylinder so as to be able to advance and retreat, and when moving forward, the communication port to the injection nozzle and the communication port to the supply path are closed, and when retreating A pre-plastic injection molding apparatus comprising a valve body that opens a communication port to the injection nozzle and a communication port to the supply path.   In the injection cylinder, an advancing / retreating shaft portion having a long rod shape in the front and rear direction is provided so as to be able to advance and retreat, and a valve body is fixed to the front end portion of the advancing / retreating shaft portion, and an injection plunger is formed in an annular shape so 2. The pre-plastic injection molding apparatus according to claim 1, wherein the apparatus is movably fitted.   The pre-plastic injection molding apparatus according to claim 2, wherein the advance / retreat shaft portion is selectively provided from a plurality of advance / retreat shaft portions having different diameters.

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