JP2007190863A - Injection molding apparatus and material feeding method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding apparatus which can solve various problems caused by insufficient deaeration, by enabling an increase in the deaeration effect of removing gas, air and moisture, generated during melting, from a screw, and a material feeding method for the injection molding apparatus. <P>SOLUTION: When the material is fed into the cylinder of the injection molding apparatus, it is fed toward a lower part or a side surface part of the cylinder, and the direction of the deaeration is set as a direction opposite to a material feeding direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an injection molding apparatus and a material supply method thereof, and more particularly, to an injection molding apparatus and a material supply method thereof that improve the deaeration effect.

  Conventionally, the following Patent Documents 1 to 3 are known as this type of apparatus. According to these documents, in order to discharge gas and moisture generated in the resin melted in the heating cylinder to the outside of the cylinder, a method of controlling the degree of decompression in the cylinder with a vacuum device and a method of adjusting the supply amount of the resin In addition, a method of injecting an inert gas into a cylinder, a method of performing injection molding with an optimum deposition amount by adjusting an air supply amount, and combinations thereof are already known.

  This will be described below with reference to FIG. The screw 1 of the injection molding machine shown in FIG. 3 is inserted into the cylinder 2 and the resin 4 supplied from the material tank 5 is supplied by its own weight fall and stored in the hopper 3. The amount of resin to be stored is controlled in advance by the supply sensor 6 and is sent to the surface of the screw 1 through the shutter below the hopper 3. The sent resin is melted and kneaded by the rotation of the screw in the heating cylinder of the injection device.

At this time, in order to remove the gas flowing in from the hopper 3, the moisture contained in the resin, or the gas generated by the heat of the additive in the resin melted in the heating cylinder, it has been conventionally ( 1) Method of opening to the upper part of the hopper 3, (2) Method of opening a slight gap behind the screw 1, (3) Vacuum pump 7 connected to the hopper 3 or suction as an improved version of (1) A method of sucking with a blower is employed.
JP 2002-347073 A JP 2001-71363 A JP 2002-144386 A

  However, in these technologies, the resin supply port and the pressure reducing port such as a vacuum apparatus are the same or close to each other, so the flow of gas / air to be degassed is easily hindered by the supplied resin, Gas / air and moisture 8 cannot be sufficiently deaerated. For this reason, the quality of the injected purge resin must be inspected, and the quality of the molded product after injection molding must be inspected. There was a lot of waste of resin due to so-called try-and-error, which takes time to suppress the variation in the feed amount of the resin and adjust the optimum pressure reduction degree.

  On the other hand, it is difficult to obtain a sufficient effect only by adjusting the material supply and the degree of decompression. In automatic molding, the gas and moisture evaporated during melting are reattached to the resin sent from one to the next. It was inducing a defect.

  For example, in order to increase the removal venting effect, each equipment manufacturer and injection machine manufacturer adjust the amount of resin supplied by a commercially available feeder and the amount of pressure reduced by a vacuum pump or suction blower. There was a problem.

(1) Since the resin supply and the vacuum connection port are the same, if the gas generated from the molten resin flows into the rear of the screw, the phenomenon of adhering to the resin again occurred.
(2) Further, if the above-mentioned gas flows forward, it appears as dirt on the cavity surface of a mold (not shown), which adversely affects the molded product.
(3) Gas from the molten resin was the main factor, leading to abnormal corrosion and wear outside the screw and inside the cylinder.
(4) Depending on the degree of vacuum adjustment, resin burns due to oxidation in the screw and black spots of carbides were induced.

  The present invention has been made to solve the above-described conventional problems, and an injection molding apparatus and an injection molding method capable of improving the effect of degassing gas, air and moisture generated during melting from a screw. The purpose is to get.

  In order to solve the above-described problems, the present invention sets the supply direction for supplying the material to the cylinder as a lower part or a side part of the cylinder, and deaeration as the direction facing the supply direction.

  In this injection molding apparatus, the material is supplied by a quantitative feeder that is airtightly partitioned.

  Further, the material supply port and the vacuum device connection port are separated, and the inside of the cylinder and the material supply unit are hermetically sealed.

  Further, the present invention is characterized in that a feeder adjusting means for adjusting the rotation speed of the material supply feeder screw to the optimum plasticizing time of the screw by a servo motor or a variable speed motor is provided.

  The present invention is also a material supply method for an injection molding apparatus that supplies material to an injection molding apparatus, wherein a supply direction for supplying the material to the cylinder is a lower part or a side part of the cylinder, and deaeration is performed in the supply direction. This is the direction in which they face each other.

  According to the present invention, it is possible to improve the degassing effect of the gas, air and moisture generated during melting from the screw, thereby solving various problems caused by insufficient degassing. There is an effect.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
In this embodiment, the resin is supplied from the lower part or the side part of the cylinder instead of falling from its own weight from the conventional hopper 3 part, and the supply amount is matched with the retreating speed of the screw 1 to determine the feeder feeder 9 The optimum supply amount is controlled by the servo motor 13 or the variable speed motor.

  Thus, the gas, air, and moisture generated at the time of melting can be kept in the screw 1 by maintaining the transportation in the so-called starvation state in which the gas, air, and moisture are easily removed, instead of the transportation in the conventional screw groove portion being full. It is easier to pull out from behind.

  Furthermore, it is possible to increase the deaeration effect which has been impossible in the past by suctioning at a high pressure by a vacuum pump connected to the upper part of the cylinder.

  In the present embodiment, since the resin is supplied from the lower side of the cylinder 2, the metering feeder screw 9 is rotatably inserted into the metering feeder cylinder 10 which is kept airtight with a vacuum seal. The quantitative feeder screw 9 is rotated via a servo motor 13 so that the resin can be supplied by utilizing a resin transporting action, that is, a resin propulsion force. As a result, the amount of resin applied to the screw 1 is optimally controlled.

  Further, the amount of resin supplied in the screw 1 is reduced as much as possible, and the inside of the cylinder 2 is brought into an optimum supply state by maintaining a stable starvation state. Using this optimum supply state, the vacuum pump 7 enables high pressure reduction from the upper part of the cylinder via the filter 11 and the vacuum pump connection part 12. This high pressure reduction in the cylinder makes it possible to degas the gas, air and moisture discharged from the molten resin more efficiently than before.

Next, an example of the injection molding method will be described with reference to the flowchart shown in FIG.
First, the operator (molding engineer) repeats the molding process based on normal molding conditions, and confirms that the quality and plasticization time of the molded product are shorter than the cooling time and that the plasticization time is stable. For example, after 20 shots have been formed from the start of molding (step 1), the operator then increases the rotational speed of the quantitative feeder screw 9 so that the groove of the screw 1 is filled with resin as in the conventional case. .

  Subsequently, the operator confirms the actual relationship of “cooling time−plasticizing time ≦ 1 sec” (step 2). Therefore, for example, when the plasticizing time is considerably shorter than the cooling time, the rotation speed of the quantitative feeder screw 9 is automatically adjusted by the arithmetic processing function provided in the injection molding machine so that the plasticizing time ends before the cooling time is completed. Slow down.

  For example, if the cooling time arbitrarily set by the operator in the arithmetic processing function is 15 seconds and the actual plasticizing time of the screw 1 when the current quantitative feeder screw 9 has a rotation speed of 100 r / min is 10.5 seconds, A signal for setting the screw rotation speed of the next cycle to, for example, 70 r / min so that the plasticizing time becomes substantially equal to the cooling time is automatically sent to the servo motor 13 so that the actual plasticizing time becomes equal to 15 sec. Adjustment is repeated (step 3).

  Further, in the above-described process, high pressure reduction is always performed from the upper part of the cylinder 2 by the vacuum pump 7, thereby making it possible to remove the optimum air / moisture matched with actual molding and gas at the time of melting.

  Based on the above, the basic operation is the relationship of “cooling time−plasticizing time ≦ 1 sec”, and the plasticizing time of the screw 1 (screw retreating time) and the rotational speed of the quantitative feeder screw 9 are automatically controlled as needed for continuous molding. (Step 4).

  As described above, according to the present invention, the resin is supplied from the lower part or the side part of the cylinder by the quantitative feeder, and the high pressure reduction is maintained by the vacuum pump or the suction blower from the upper part of the cylinder. This makes it possible to reduce the following molding defects.

(1) Resin is supplied by a quantitative feeder that keeps airtight from the lower part or side part of the cylinder, and the resin to be supplied is degassed by a high-pressure reduction vacuum device from a direction different from the resin supply port. By not contacting with moisture or gas generated by melting in the cylinder, inflow of gas to the mold can be prevented and a high deaeration effect can be obtained.

(2) Abnormal corrosion and wear can be prevented by preventing local heat generation due to resin shearing and minimizing gas generation from resin supply by a quantitative feeder.

(3) Resin burns and carbide black spots are reduced by the same effects as in (2).

(4) Since the gas can be prevented from flowing into the mold, the number of mold maintenance can be reduced.

(5) Reduction of the amount of oxygen in the cylinder can also prevent formation of black spots due to resin burning of the molded product and carbide.

(6) It is possible to use undried resin (resin that needs to be pre-dried) by high pressure reduction by a vacuum pump, and it is possible to reduce the drying process and management.

(7) Since the resin supply of the quantitative feeder screw 9 in accordance with the retraction speed of the screw 1 is controlled by the servo motor 13 or the variable speed motor, it is possible to reduce the variation in the molded product weight and the dimensional variation due to the plasticizing time variation. .

(8) Since the screw 1 is rotated by the starvation supply of the resin, by minimizing the resistance in the solid layer of the resin, the rotational torque is reduced and an energy saving effect can be expected.

It is a schematic block diagram of the injection molding apparatus which is one Embodiment of this invention. It is an example of the flowchart of the injection molding control method of this invention. It is a schematic block diagram of an example of the vacuum pump and material supply apparatus which are used for the injection molding apparatus of the conventional injection molding machine.

Explanation of symbols

1 screw, 2 cylinder, 3 hopper, 4 resin (material), 5 material tank, 6 supply sensor, 7 vacuum pump, 8 gas / air and moisture, 9 metering feeder screw, 10 metering feeder cylinder, 11 filter, 12 vacuum pump Connection part, 13 Servo motor.

Claims (5)

  An injection molding apparatus in which a supply direction for supplying material to a cylinder is a lower part or a side part of the cylinder, and deaeration is a direction opposite to the supply direction. The injection molding apparatus according to claim 1,
An injection molding apparatus, wherein the material is supplied by a quantitative feeder that is airtightly partitioned. In the injection molding device according to claim 1 or 2,
An injection molding apparatus, wherein the material supply port and the vacuum device connection port are separated, and the inside of the cylinder and the material supply unit are hermetically sealed. The injection molding apparatus according to claim 2,
An injection molding apparatus comprising feeder adjusting means for adjusting a rotation speed of a material supply feeder screw to an optimum plasticizing time of a screw by a servo motor or a variable speed motor. A material supply method for an injection molding apparatus for supplying material to an injection molding apparatus,
A material supply method for an injection molding apparatus in which a supply direction for supplying material to a cylinder is a lower part or a side part of the cylinder, and deaeration is a direction opposite to the supply direction.

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