JPH04168024A - Injection molding method - Google Patents

Abstract

PURPOSE:To make molding with more stable quality possible and make it possible to prevent non-conforming article due to the burning of resin or the like from developing by a method wherein the temperature of an injection machine and, at the same time, the injection speed are controlled on the basis of the detected temperature of the resin at the injection tip part of the injection machine. CONSTITUTION:A temperature sensor 4, which directly detects the temperature of the resin injected from an injection machine 2, is arranged at the injection tip part 2c of the injection machine 2 so as to come into contact with the resin. The resin temperature detected with the temperature sensor 4 is inputted in a temperature controller 5 so as to control a heater 3 in response to the resin temperature in order to control the injection machine. Further, the resin temperature detected with the temperature sensor 4 is converted with a temperature-to- speed converter 6 to speed controlling value, in response to which the rotation of a screw 2 is controlled with a screw controller 7.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an injection molding method suitable for manufacturing information recording media such as magneto-optical disks.

(Prior Art) FIG. 3 is a configuration diagram showing a conventional injection molding apparatus (injection molding method) consisting of a molding die 10 and an injection machine 11.

A plurality of heaters 12 are arranged around the main body 11a of the injection machine 11 to control the temperature of the injection machine 11 itself.

Temperature sensors 13a, 13 disposed in the main body 11a and the injection tip (nozzle part) 11b of the injection machine 11
b (for example, a thermocouple embedded at a depth of several +011 from the outer wall), the heater controller 14 controls the heater 12 so that the temperature of the injection machine 11 itself is equal to the set temperature. , injection molding was performed.

(Problem to be Solved by the Invention) The resin temperature during injection is determined by the set temperature of the heater 12, the screw rotation speed of the injection machine 12, and the screw back pressure.

It also changes depending on molding conditions such as injection speed. Therefore, even if the set temperature of the heater 12 is the same, if the molding conditions differ, the resin temperature will naturally vary.

Furthermore, even if the molding conditions are the same, the temperature sensor 13
Since there is a gap (distance) between a, 13b and the injected resin, when the resin temperature changes, the temperature sensors 13a, 13b
Even if the heater 12 senses a temperature change in the resin and raises or lowers the temperature of the heater 12, there is a time delay before the temperature change in the heater 12 is conducted and transmitted to the resin. Therefore, there is a difference between the set temperature and the resin temperature, and the resin temperature for each molding is not constant and has a wide variation.

Furthermore, when the resin temperature changes, the kinematic viscosity coefficient of the resin changes, and the fluidity of the resin changes. Therefore, the shape 1 warp angle, birefringence, transferability, etc. of the information recording carrier, which is a molded product, change.

The amount of temperature change during each molding causes variations in the properties of the molded product, which is a big problem especially when molding information recording media such as magneto-optical disks.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides an injection molding method using an injection molding device comprising a molding die and an injection machine. To provide an injection molding method in which a resin temperature is detected, the temperature of the injection machine itself is controlled based on the detected resin temperature, and the injection speed is controlled based on the detected resin temperature. .

(Function) Even with temperature control, there is a time lag until the resin temperature actually changes, but until the resin temperature becomes equal to the set temperature, injection is performed according to the change in viscosity coefficient due to temperature change. Speed is controlled.

(Example) An example of the injection molding method according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing an injection molding apparatus in which the injection molding method is carried out, and FIG. 2 is a system diagram illustrating the injection molding method.

First, the configuration of the injection molding apparatus will be explained with reference to FIG. The injection molding apparatus consists of a molding die 1 and an injection machine 2, and a plurality of heaters 3 are arranged around a main body 2a of the injection machine 2 to control the temperature of the injection machine 2 itself.

The injection machine 2 is configured to inject resin (not shown) into the molding die 1 in accordance with the rotation of an injection screw 2b.

Furthermore, a temperature sensor 4 that directly detects the temperature of the resin injected from the injection machine 2 is disposed at the injection tip (nozzle part) 2c of the injection machine 2 so as to be in contact with the resin.

The resin temperature detected by temperature sensor 4 is the temperature (heater)
The temperature is input to the controller 5, and the heater 3 is controlled according to the resin temperature, thereby controlling the temperature of the injection machine.

Further, the resin temperature detected by the temperature sensor 4 is converted into a control speed value by a temperature/speed converter 6 as described later, and the screw controller 7 controls the screw 2b according to this control value.
The rotation of the resin is controlled, and the resin injection speed is feedback-controlled in accordance with the detected resin temperature.

Next, the injection molding method will be explained with reference to the system diagram shown in FIG.

As shown in the figure, this injection molding method directly detects and measures the resin temperature with a temperature sensor 4 installed at a position reaching the resin passage part of the injection tip 2c of the injector 2, and the temperature information is is fed back to the set temperature of the heater 3, and the resin injection speed is also feedback-controlled based on this temperature information. That is, even if the heater temperature is changed, there is a time lag until the resin temperature actually changes. Therefore, until the resin temperature becomes equal to the set temperature, the viscosity coefficient changes as the temperature changes.
It is designed to stabilize the quality of the actual molded substrate as much as possible by changing the set value of the injection speed.

Here, the relationship between resin temperature and injection speed is that if the molten resin at the time of injection is assumed to be a Newtonian fluid, the viscosity coefficient and stress are in a proportional relationship when the speed is constant, and the relationship is due to the shear force at the time of injection. If you ignore local shear heat generation,
Injection force and viscosity coefficient are linearly proportional.

Therefore, if the viscosity coefficient of the resin at each temperature is known, in order to convert the temperature difference between the set temperature and the resin temperature into injection speed, it is sufficient to multiply the following relational expression between temperature and viscosity coefficient by a constant. Become.

Assuming that the viscosity coefficient μ at the set temperature, the injection speed U, the viscosity coefficient μ at the actual resin temperature, and the injection speed U, μ/μo-u/u.

and here, The following relational expression holds true.

However, F: Injection force R: Screw radius A: Area of wall surface Also, the viscosity coefficient at temperature T"C is -0,8) μ-ρo (l-αT)・(e (α, m , is a constant), so the temperature can be converted to the injection speed based on the above equation.

(Specific Molding Example) Next, Table 1 shows the molding results when 100 substrates were continuously molded under the following molding conditions.

Molding conditions Resin, polycarbonate, Mitsubishi Gas Chemical Kneepilon 84
000 N-606 Resin temperature, 340℃ Set injection speed: 40% (injection pressure 25QOkgf'/cd
) Molded product: φ130'Xtl, 2 Mold temperature = 115℃ Molding machine used: JSW, J50DK Screw diameter:
φ28 Table Temperature difference: Difference between set temperature during molding and actual resin temperature Variation: Difference between maximum and minimum values at the same position of 100 molded substrates Incidence of defective products: Out of 100 sheets Percentage of the number of defective products Warp angle: γ-Radial warp angle plate refraction at 55 angles: γ-
As is clear from the molding results in Table 1, the injection molding method described in this example has a small temperature difference, little variation in warpage angle and variation in birefringence, and reduces the occurrence of defective products. The yield is also low, and good molded products can be obtained.

(Effects of the Invention) As detailed above, the injection molding method of the present invention includes
It has the following features.

(A) By reducing the change in resin temperature for each molding, variations caused by non-uniform resin temperature are reduced, and molding with constant quality is possible.

(a) By compensating for temperature differences by changing the injection speed according to the amount of change in resin temperature, molding with more stable quality is possible.

(1) By directly measuring the resin temperature, excessive heating of the resin can be prevented, and defective products such as resin discoloration can be prevented.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an injection molding apparatus in which the injection molding method according to the present invention is carried out, Fig. 2 is a system diagram explaining the injection molding method according to the present invention, and Fig. 3 is a diagram showing a conventional injection molding apparatus. It is a diagram. DESCRIPTION OF SYMBOLS 1... Molding mold, 2... Injection machine, 2a... Main body part, 2b... Injection screw, 2C... Injection tip part (nozzle part), 3... Heater, 4... ...Temperature sensor, 5...Temperature (
Heater) controller, 6... Temperature/speed converter, 7... Screw controller. Patent applicant: Victor Japan Co., Ltd. Figure 1 Figure 2 Figure 6

Claims (1)

[Scope of Claims] An injection molding method using an injection molding device comprising a molding die and an injection machine, comprising: detecting a resin temperature at an injection tip of the injection machine;
An injection molding method characterized in that the temperature of the injection machine itself is controlled based on the detected resin temperature, and the injection speed is controlled based on the detected resin temperature.