JP2012250449A - Device and method for discharging at fixed amount - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and method for discharging a fixed amount of molten resin having a uniform density.SOLUTION: A measurement chamber 9 is sealed by moving a needle valve 11 to a closing position after the measurement chamber 9 is filled with molten resin from a screw 2, while a shutter member 13 is moved to a closing position. A plunger 12 is actuated so that a pressure value detected by a pressure detection sensor 10 provided in the measurement chamber 9 becomes a reference value stored in a memory part 19. The shutter member 13 is moved to an opening position so that the molten resin is discharged from an outlet 9b of a nozzle 6 by precise driving of the plunger 12.

Description

  The present invention relates to a molten resin quantitative discharge device and a quantitative discharge method.

  A compression molding apparatus having a compression mold includes a fixed-quantity discharge device that discharges molten resin, and is configured to supply a predetermined amount of molten resin to an opened lower mold of the compression mold. The compression molding apparatus includes a cutting mechanism and a conveyance mechanism together with the compression molding machine, cuts the resin discharged to the lower mold by the cutting mechanism, conveys the lower mold to the compression molding machine by the conveyance mechanism, and performs compression molding. . At this time, the variation in the weight of the resin discharged to the lower mold is a variation in the shape of the molded body.

  For example, when a precision part such as a lens is manufactured by a compression molding method, the weight of the supplied material may be required to be accurate to 1 mg or less in order to suppress variations in lens thickness. Therefore, in the material supply step of the compression molding method, a method capable of discharging a very accurate weight of molten resin is required.

  Conventionally, as a method for quantitatively discharging molten resin, a method of discharging a molten resin plasticized by a plasticizing portion made of a screw from an opened discharge port by rotating a predetermined amount of the screw or driving the screw back and forth. It has been known. Also, a method is known in which molten resin plasticized by a screw is filled in a measuring chamber and discharged from an open discharge port by a front-rear drive of a precision-driveable plunger provided in the measuring chamber (patent) Reference 1). In this Patent Document 1, after the molten resin is filled in the measurement chamber in a state where the discharge port is closed, the flow path between the plasticizing portion and the measurement chamber is closed, and then the discharge port is opened, and the measurement chamber is opened. Discloses a method of discharging by driving the plunger back and forth. According to this method, since the molten resin is filled into the measuring chamber with the discharge port closed, the filling of the molten resin into the entire measuring chamber is compensated. Further, by closing the flow path between the plasticizing portion and the measuring chamber, it is possible to prevent the molten resin from flowing back to the plasticizing portion during discharge, and it is possible to discharge accurately.

JP-A-3-137959

  However, in the conventional discharge method, since the density of the molten resin is not controlled when the molten resin is measured, there is a problem in that the weight of the discharged molten resin varies. That is, the density of the molten resin filled in the measuring chamber varies due to the difference in the plasticized and melted state of the molten resin filled in the measuring chamber from the plasticizing section and the influence of temperature unevenness in the flow path. For this reason, even when an accurate volume of molten resin is ejected, the weight may vary.

  On the other hand, as a means for controlling the density of the resin, it is considered that when the molten resin is filled into the measuring chamber from the plasticizing portion, pressure is applied from the plasticizing portion side to control the internal pressure of the molten resin in the measuring chamber. It is done. However, in the pressurization from the plasticizing portion side, the viscosity of the molten resin in the flow path varies due to the temperature unevenness of the flow path, and it is difficult to accurately control the molten resin internal pressure in the measuring chamber. Moreover, in order to prevent the backflow to the plasticizing part side at the time of discharge, the flow path between the plasticizing part and the measurement chamber is closed with a needle valve. Since the internal pressure of the molten resin in the measuring chamber is changed by driving the needle valve, it is difficult to accurately control the internal pressure of the molten resin in the measuring chamber immediately before discharge.

  Therefore, an object of the present invention is to provide a fixed amount discharge apparatus and a fixed amount discharge method capable of discharging a molten resin having a constant density.

  The metering discharge device of the present invention includes a measuring chamber having a plasticizing portion for plasticizing a resin raw material, an introduction port for introducing a molten resin from the plasticizing portion, and a discharge port for discharging the molten resin. A formed main body, a needle valve that opens and closes the introduction port, a shutter member that opens and closes the discharge port, a plunger that is disposed in the measurement chamber and presses the molten resin filled in the measurement chamber, and A pressure detection sensor for detecting the pressure in the measurement chamber; a storage unit for storing a reference value of the pressure in the measurement chamber; and a drive control unit for driving and controlling the needle valve, the shutter member, and the plunger, The drive control unit operates the needle valve and the shutter member to a closed position to discharge the molten resin filled in the measurement chamber from the discharge port, thereby closing the measurement chamber. Then, the plunger is operated to pressurize the molten resin filled in the measurement chamber so that the pressure detection value detected by the pressure detection sensor becomes a reference value stored in the storage unit. .

  The metering discharge method of the present invention includes a measuring chamber having a plasticizing portion for plasticizing a resin raw material, an introduction port for introducing a molten resin from the plasticizing portion, and a discharge port for discharging the molten resin. A formed main body, a needle valve that opens and closes the introduction port, a shutter member that opens and closes the discharge port, a plunger that is disposed in the measurement chamber and presses the molten resin filled in the measurement chamber, and A metering unit comprising a pressure detection sensor for detecting the pressure in the measuring chamber, a storage unit for storing a reference value of the pressure in the measuring chamber, and a drive control unit for drivingly controlling the needle valve, the shutter member, and the plunger. In a quantitative discharge method using a discharge device, the drive control unit operates the needle valve to an open position and the shutter member to a closed position, and fills the measurement chamber with molten resin from the introduction port. And after the filling of the molten resin into the measuring chamber is completed in the filling step, the needle valve is moved to a closed position by the drive control unit to make the measuring chamber a sealed space, and the pressure detection A pressurizing step of operating the plunger by the drive control unit so as to pressurize the molten resin filled in the measuring chamber so that the pressure detection value detected by the sensor becomes a reference value stored in the storage unit; After the pressure detection value detected by the pressure detection sensor in the pressurizing step becomes the reference value, the drive control unit moves the shutter member to the open position and operates the plunger. And a discharge step of discharging the molten resin from the discharge port.

  According to the present invention, the measurement chamber is a sealed space, and the molten resin is pressurized by the plunger so that the pressure detection value detected by the pressure detection sensor becomes the reference value. The density of can be made constant. Therefore, the variation in the weight of the molten resin for each discharge can be reduced.

It is a mimetic diagram showing a schematic section of a fixed amount discharge device concerning an embodiment of the present invention. It is a schematic diagram which shows the schematic cross section of the quantitative discharge apparatus which concerns on this embodiment of this invention, Comprising: The schematic diagram which showed each process of the filling process, pressurization process, and discharge process of the quantitative discharge method using a quantitative discharge apparatus one by one. It is. (A) is a filling process, (b) is a pressurizing process, and (c) is a discharging process.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a schematic cross-section of a quantitative discharge device according to an embodiment of the present invention.

  In FIG. 1, a quantitative discharge device 100 includes a hopper 1 into which a resin raw material to be a molten resin is charged, a screw 2 as a plasticizing part that heat-kneads and plasticizes the resin raw material charged into the hopper 1, It has. The fixed amount dispensing device 100 includes a barrel 3 that is a cylindrical body that houses the screw 2. The barrel 3 is provided with a main body portion 7 including an upper manifold 4, a lower manifold 5, and a nozzle 6.

  In the upper manifold 4, a flow path 8 of molten resin supplied from the screw 2 is formed. The lower manifold 5 and the nozzle 6 have an introduction port 9a and a discharge port 9b, and a measuring chamber 9 for filling and pressurizing molten resin is formed. The measuring chamber 9 is provided with a pressure detection sensor 10 for detecting the pressure of the measuring chamber 9 (that is, the pressure of the molten resin filled in the measuring chamber 9). The flow path 8 and the measurement chamber 9 communicate with each other via an introduction port 9a, and a needle valve 11 is provided at a position (the flow path 8 in the present embodiment) where the introduction port 9a is opened and closed. The needle valve 11 can open and close the introduction port 9a by moving between an open position for opening the introduction port 9a and a closed position for closing the introduction port 9a.

  The fixed amount discharge device 100 is slidably disposed in the measuring chamber 9 and includes a plunger 12 that allows precise back-and-forth movement and presses the molten resin filled in the measuring chamber 9. Outside the measuring chamber 9, there is provided a shutter member 13 that can move between an open position for opening the discharge port 9b and a closed position for closing the discharge port 9b.

  Here, each of the barrel 3, the upper manifold 4, the lower manifold 5, and the nozzle 6 is provided with a heater and a temperature sensor so that the temperature can be adjusted precisely and individually. That is, the barrel 3, the upper manifold 4, the lower manifold 5, and the nozzle 6 are each controlled to have a constant temperature.

  The fixed amount dispensing apparatus 100 includes a needle valve driving unit 14 that drives the needle valve 11, a shutter driving unit 15 that drives the shutter member 13, a plunger driving unit 16 that drives the plunger 12, and a control unit 17 that controls these driving units. The drive control part 18 which consists of these is provided. That is, the drive control unit 18 drives and controls the needle valve 11, the shutter member 13, and the plunger 12.

  Further, the fixed amount discharge device 100 is a value indicating the pressure in the measuring chamber 9 (that is, the pressure of the molten resin filled in the measuring chamber 9), and stores a reference value to be compared in advance. It has.

  FIG. 2 is a schematic diagram showing a schematic cross-section of the quantitative discharge device according to the present embodiment of the present invention, in which each step of the filling step, pressurizing step, and discharge step of the quantitative discharge method using the quantitative discharge device is sequentially performed. It is the shown schematic diagram.

  First, the resin raw material put into the hopper 1 is heated and kneaded by the screw 2 to be plasticized. Thereafter, the plasticized molten resin passes through the flow path 8 by the rotation of the screw 2 and is introduced into the measuring chamber 9. At this time, the drive controller 18 operates the needle valve 11 to the open position and the shutter member 13 to the closed position, as shown in FIG. Further, the drive control unit 18 retracts the plunger 12 to a preset retracted position. Thereby, the measurement chamber 9 is filled with the molten resin through the introduction port 9a, and the measurement chamber 9 with the discharge port 9b closed is filled with the molten resin (a filling step).

  Next, after the filling of the molten resin into the measuring chamber 9 is completed in the filling step described above, the drive control unit 18 maintains the shutter member 13 in the closed position as shown in FIG. The needle valve 11 is moved to the closed position. Thereby, the measurement chamber 9 becomes a sealed space. That is, a closed space defined by the lower surface of the needle valve 11, the front surface of the plunger 12, and the upper surface of the shutter member 13 is created. And the drive control part 18 operates the plunger 12 in the direction (arrow X direction) which presses molten resin so that the pressure detection value detected by the pressure detection sensor 10 may become the reference value memorize | stored in the memory | storage part 19. . By the precision driving of the plunger 12, the molten resin filled in the measuring chamber 9 is pressurized (pressurizing process). The pressurizing operation by the control of the drive control unit 18 described above is performed prior to discharging the molten resin filled in the measuring chamber 9 from the discharge port 9b. As described above, the molten resin filled in the measuring chamber 9 has a constant density for each pressurizing step when a predetermined pressure is applied.

  Next, after the pressure detection value detected by the pressure detection sensor 10 in the pressurizing step becomes the reference value, the drive control unit 18 opens the shutter member 13 as shown in FIG. The plunger 12 is further moved in the arrow X direction while being moved to the position. At this time, the needle valve 11 is maintained in the closed position. Thereby, the molten resin R filled in the measuring chamber 9 is pushed by the plunger 12 and discharged from the discharge port 9b (discharge process).

  With the above operation, the molten resin R having a constant density can be discharged by a fixed volume every time it is discharged. Accordingly, it is possible to discharge a very accurate weight of the molten resin, and to reduce variations in the weight of the molten resin for each discharge.

  In addition, by applying the above-described molten resin quantitative discharge method to the material supply step of the compression molding method, the shape variation of the compression molded product can be extremely reduced.

  In addition, by manufacturing precision optical elements such as lenses and prisms by the compression molding method described above, variations in element shape can be reduced, and variations in light collection efficiency, focal length, reflection efficiency, etc. can be extremely reduced. it can.

  In addition, the resin raw material used for this invention is not specifically limited, There will be no problem if it is a thermoplastic resin applicable to this manufacturing method. For example, polyolefin resin, acrylic resin, polycarbonate resin, polyethylene terephthalate, or the like can be used.

[Example 1]
As an example of the present invention, molten resin was discharged using the method of the present invention, and the variation in the discharge weight was evaluated. As a raw material resin, ZEONEX E48R manufactured by Nippon Zeon Co., Ltd., which is a polyolefin resin, was used. The temperatures of the barrel 3, the upper manifold 4, the lower manifold 5, and the nozzle 6 are 220 ° C., 250 ° C., 270 ° C., and 250 ° C., respectively. With the shutter member 13 closed, the metering chamber 9 is filled with the molten resin plasticized by the screw 2 and the needle valve 11 is closed. Thereafter, the internal pressure of the molten resin is adjusted to 8 MPa by driving the plunger 12, and the pressurized state is maintained for 0.5 seconds. Thereafter, the plunger 12 is stopped, and at the same time, the shutter member 13 is opened and discharged by the position control drive of the plunger 12. The driving distance of the plunger 12 is 2.7 mm from the pressure holding stop position. Finally, the molten resin R discharged from the discharge port 9b was cut at the tip surface of the nozzle 6, and the weight of the cut resin was measured with an electronic balance.

[Comparative Example 1]
As a comparative example, in the method of the present invention, molten resin was discharged without performing a pressurizing step, and the discharge weight variation was evaluated. The raw material resin, the temperature conditions, and the driving distance of the plunger 12 are the same as in the first embodiment. With the shutter member 13 closed, the metering chamber 9 is filled with the molten resin plasticized by the screw 2 and the needle valve 11 is closed. Thereafter, the shutter member 13 was opened and discharged by the position control drive of the plunger 12. Finally, the molten resin R discharged from the discharge port 9b was cut at the tip surface of the nozzle 6, and the weight of the cut resin was measured with an electronic balance.

[Example 2]
Panlite AD-5503 manufactured by Teijin Chemicals Ltd., which is a polycarbonate resin, was used as the raw material resin, and the molten resin was discharged using the method of the present invention, and the discharge weight variation was evaluated. The discharge method, discharge conditions, and evaluation method are the same as in the first embodiment.

[Comparative Example 2]
As a comparative example, the same raw material resin as in Example 2 was used, and in the method of the present invention, the molten resin was discharged without performing the pressing step, and the discharge weight variation was evaluated. The discharge method, discharge conditions, and evaluation method are the same as in Comparative Example 1.

  Table 1 shows the evaluation results of Example 1, Comparative Example 1, Example 2, and Comparative Example 2. As can be seen from the results shown in Table 1, in the embodiment of the present invention, the difference between the maximum discharge weight and the minimum discharge weight is smaller than that of the comparative example in which the present invention is not performed, that is, the variation in the discharge weight is small. . This is because in the embodiment, there is a pressurizing step, and the density of the molten resin in the measuring chamber is constant for each discharge. Here, the average discharge weight is greatly different between the example and the comparative example. This is because, in the embodiment, the density of the molten resin in the measuring chamber is increased in the pressurizing step, so that even the same capacity becomes heavy. Further, since the molten resin internal pressure in the measuring chamber is increased in the pressurizing step, the molten resin internal pressure becomes the discharge pressure when the shutter member 13 is opened, and the resin is discharged more than the driving amount of the plunger 12. However, this discharge weight is proportional to the drive amount of the plunger 12, and it is possible to obtain a desired discharge weight by adjusting the drive amount of the plunger 12.

[Example 3]
As an example of the present invention, a lens was manufactured by using the discharge method of the present invention in the material supply step of the compression molding method, and the variation in lens thickness was evaluated. The shape of the manufactured lens is a biconvex spherical shape having a diameter of 10 mm. As a raw material resin, ZEONEX E48R manufactured by Nippon Zeon Co., Ltd., which is a polyolefin resin, was used. The discharge method and discharge conditions are the same as in the first embodiment. The discharged molten resin R is placed on a lower mold that is one side of the lens, and the molten resin R is cut at the tip surface of the nozzle 6. Next, the lower mold on which the resin is placed is conveyed to a compression molding machine, and the lower mold is fitted into the barrel mold. Thereafter, an upper die that is slidably provided on the barrel die is driven in advance, and a resin is sandwiched between the upper die and the lower die to perform compression molding. The compression molding conditions are as follows: the temperature of the upper mold, the lower mold, and the barrel mold at the start of compression is 180 ° C., the temperature of the upper mold, the lower mold, and the barrel mold at the end of the compression are 130 ° C., respectively. 5 MPa. Finally, the thickness of the manufactured lens was measured with a dial gauge.

[Comparative Example 3]
As a comparative example, in the method of the present invention, a method in which the pressurizing step was not performed was used in the material supply step of the compression molding method to manufacture a lens, and the variation in lens thickness was evaluated. The shape of the manufactured lens is the same as in Example 3. The discharge method and discharge conditions are the same as in Comparative Example 1. The compression molding method, molding conditions, and evaluation method are the same as in Example 3.

  Table 2 shows the evaluation results of Example 3 and Comparative Example 3. As can be seen from the results shown in Table 2, in the examples of the present invention, the variation in the lens thickness is small compared to the comparative example in which the present invention is not implemented. This is because the weight variation of the resin supplied to the compression molding is reduced by the discharge method of the present invention.

  The present invention can be used for a material supply process and a material supply apparatus of various compression molding methods. In particular, it is suitable for a material supply process and a material supply apparatus of a compression molding method for molding optical elements such as lenses and prisms.

DESCRIPTION OF SYMBOLS 2 ... Screw (plasticization part), 7 ... Main-body part, 9 ... Metering chamber, 9a ... Inlet port, 9b ... Discharge port, 10 ... Pressure detection sensor, 11 ... Needle valve, 12 ... Plunger, 13 ... Shutter member, 18 ... Drive control unit, 19 ... Storage unit, 100 ... Quantitative discharge device

Claims (2)

A plasticizing part for plasticizing the resin raw material;
A main body portion formed with a measuring chamber having an inlet for introducing the molten resin from the plasticizing portion and an outlet for discharging the molten resin;
A needle valve that opens and closes the inlet;
A shutter member for opening and closing the discharge port;
A plunger that is disposed in the measuring chamber and presses the molten resin filled in the measuring chamber;
A pressure detection sensor for detecting the pressure in the weighing chamber;
A storage unit for storing a reference value of the pressure of the measuring chamber;
A drive control unit that drives and controls the needle valve, the shutter member, and the plunger;
The drive control unit operates the needle valve and the shutter member to a closed position to discharge the molten resin filled in the measurement chamber from the discharge port to make the measurement chamber a sealed space, A metering discharge device, wherein the plunger is operated to pressurize the molten resin filled in the measuring chamber so that a pressure detection value detected by a pressure detection sensor becomes a reference value stored in the storage unit . A plasticizing part for plasticizing the resin raw material;
A main body portion formed with a measuring chamber having an inlet for introducing the molten resin from the plasticizing portion and an outlet for discharging the molten resin;
A needle valve that opens and closes the inlet;
A shutter member for opening and closing the discharge port;
A plunger that is disposed in the measuring chamber and presses the molten resin filled in the measuring chamber;
A pressure detection sensor for detecting the pressure in the weighing chamber;
A storage unit for storing a reference value of the pressure of the measuring chamber;
A fixed amount discharge method using a fixed amount discharge device comprising the needle valve, the shutter member, and a drive control unit for driving and controlling the plunger,
A filling step of filling the metering chamber with the molten resin from the introduction port by operating the needle valve to the open position and the shutter member to the closed position by the drive control unit;
After the filling of the molten resin into the measuring chamber is completed in the filling step, the drive control unit operates the needle valve to a closed position to make the measuring chamber a sealed space, which is detected by the pressure detection sensor. A pressurizing step of operating the plunger by the drive control unit so that the pressure detection value becomes a reference value stored in the storage unit, and pressurizing the molten resin filled in the measurement chamber;
After the pressure detection value detected by the pressure detection sensor in the pressurizing step becomes the reference value, the drive control unit moves the shutter member to the open position and operates the plunger, so that the discharge is performed. And a discharging step of discharging the molten resin from the outlet.

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