JP2002154144A - Injection molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding device, in which labor of an operator is reduced by automatically correcting the temperature of a heating cylinder in correspondence with fluctuation of the characteristic value of a resin. SOLUTION: The injection molding device is equipped with a heater 5 heating the heating cylinder 4, an input device 2 inputting the characteristic value of the resin used for injection molding and a controller 3, in which the temperature of the cylinder corresponding to the characteristic value is stored and the temperature of the cylinder is selected on the basis of the characteristic value of the resin for molding inputted from the input device 2 and the heater 5 is controlled by keeping the selected temperature of the cylinder as the target value of temperature control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding apparatus for injection molding plastic.

[0002]

2. Description of the Related Art In the practice of injection molding, the flow characteristics of a resin, such as a melt index, vary due to variations in the average molecular weight and molecular weight distribution of the resin. Even in the case of such a change, if the molding is performed under the prescribed constant molding conditions, the quality of the obtained molded product fluctuates and deviates from a desired required quality range. In this case, the quality of the molded product can be ensured by correcting the temperature of the heating cylinder in accordance with the variation in the flow characteristics of the resin.

A conventional temperature correction is disclosed in Japanese Patent Application Laid-Open No. 10-3152.
As described in JP-A-91, this is achieved by dividing the heating cylinder into a plurality of temperature control zones and controlling the temperature control zone adjacent to the cooling flange. That is, the above-described temperature control zone is controlled by the main operation amount obtained by feeding back the temperature detected by the temperature sensor, and the compensation operation is performed by subtracting the margin between the main operation amount and the operation amount upper limit from the main operation amount. The temperature control is performed separately for the part controlled by the amount.

[0004]

Problems to be Solved by the Invention
No. 91 and the temperature control of the heating cylinder conventionally performed are for controlling the temperature of the heating cylinder, and not for each of the molding resins used for injection molding. Therefore, when using the resin characteristic value of the molding resin such as the flow characteristic value, the operator calculates the optimum heating cylinder temperature from the flow characteristic value of the resin with a computer, and inputs the calculated heating cylinder temperature to the molding machine. Requires manual entry into the device. Such a series of operations has a problem in that the operation time of the operator increases, the labor of the operator increases, and when the calculated heating cylinder temperature is input, an erroneous input is likely to occur.

The present invention has been made in consideration of such conventional problems, and it is possible to automatically correct the temperature of a heating cylinder in response to a change in a resin characteristic value of a resin. Accordingly, it is an object of the present invention to provide an injection molding apparatus capable of reducing the labor of an operator.

[0006]

To achieve the above object, the present invention is directed to a heating heater for heating a heating cylinder, and an input device for inputting a resin characteristic value of a molding resin used for injection molding. A cylinder temperature corresponding to the resin characteristic value is stored, and the cylinder temperature is selected based on the resin characteristic value of the molding resin input from the input device,
A controller for controlling the heater by using the selected cylinder temperature as a target value for temperature control.

In this invention, the controller stores the cylinder temperature of the heating cylinder corresponding to the resin characteristic value, and automatically determines the optimum cylinder temperature by inputting the resin characteristic value of the molding resin from the input device. select. Since the temperature of the heater is controlled by the controller, the heating cylinder can be controlled at a temperature corresponding to the molding resin. Therefore, even when the molding resin changes, the temperature of the heating cylinder can be automatically corrected, and an erroneous input can be prevented.

According to a second aspect of the present invention, a heater for heating a heating cylinder, an input device for inputting a resin characteristic value of a molding resin used for injection molding, and a relational expression between the resin characteristic value and the cylinder temperature are stored. A controller that calculates a cylinder temperature based on a resin characteristic value of the molding resin input from the input device and a relational expression, and controls the heating heater using the calculated cylinder temperature as a target value for temperature control. And characterized in that:

The controller of the present invention calculates the optimum cylinder temperature for the molding resin from the stored relational expression and controls the heater. Therefore, in the present invention,
When the molding resin is changed, the temperature of the heating cylinder can be automatically corrected, and erroneous input can be prevented.

According to a third aspect of the present invention, in the second aspect of the present invention, the relational expression indicates that the temperature target value of the heating cylinder is T.
m, the reference heating cylinder temperature is T0, the correction coefficient is C, the resin characteristic value is MI, and the reference resin characteristic value is M0.
= T0 + C (MI-M0).

By storing the relational expression of the present invention in the controller, the heating temperature of the heating cylinder can be calculated.

A fourth aspect of the present invention is the invention according to any one of the first to third aspects, wherein the resin characteristic value is an average molecular weight or a melt index.

[0013] By setting the resin characteristic value to the average molecular weight or the melt index, the temperature control according to the molding resin can be favorably performed.

[0014]

FIG. 1 shows an injection molding apparatus 1 to which an embodiment of the present invention is applied. A mold section 10 for molding a molded article having a predetermined shape by injecting a molten resin, And a resin supply unit 9 that melts the resin and injects it into the mold unit 10 is disposed on the base 11 so as to be opposed to the resin supply unit 9. The resin supply section 9 includes a heating cylinder 4 extending in the direction of the mold section 10, and the resin is melted by being heated in the heating cylinder 4. The heating cylinder 4 is heated by a heater 5. The heater 5 is connected to the controller 3.

The controller 3 has a calculation unit 7 and a temperature control unit 8, and the temperature of the heater 5 is controlled by the temperature control unit 8 to the heating cylinder 4. The operation unit 7 is connected to the input device 2 arranged outside the base 11.
The input device 2 receives a resin characteristic value of a molding resin used for injection molding, and outputs the input resin characteristic value to the arithmetic unit 7. The calculation unit 7 determines a target value for temperature control of the heating cylinder 4 based on the resin characteristic value of the molding resin input from the input device 2. As the input resin characteristic value, an average molecular weight, a melt index, a bar flow value, and the like of the resin are appropriately selected. The heating temperature is measured by attaching a thermometer 6 to the heating cylinder 4.

(Embodiment 1) In this embodiment, the temperature of the heating cylinder 4 is controlled based on a correspondence table (table) 20 shown in FIG. This correspondence table 20 is stored in the calculation unit 7 of the controller 3 in advance.

The correspondence table 20 has an average molecular weight column 21 as a resin characteristic value and a heating cylinder temperature column 22.
In the average molecular weight column 21, a plurality of average molecular weights M1, M2,
... are stored in the heating cylinder temperature column 22.
The heating cylinder temperatures Tm1, Tm2,... Corresponding to the respective average molecular weights M1, M2,.
The calculation unit 7 receives the average molecular weight of the resin,
The cylinder temperature of the heating cylinder corresponding to the average molecular weight is selected, and the temperature control unit 8 controls the heater 5 using the selected cylinder temperature as a target value.

In this embodiment, the operator inputs the average molecular weight M of the molding resin used for molding into the input device 2 before starting the molding of the resin. The input average molecular weight M is output to the arithmetic unit 7, whereby the arithmetic unit 7 selects a target value Tm of the heating cylinder temperature corresponding to the average molecular weight M from the correspondence table 20. The selected target value Tm is output to the temperature control unit 8, and the temperature control unit 8 controls the heater 5 so that the temperature of the heating cylinder 4 becomes the target value Tm. This control can be performed, for example, by controlling the current supplied to the heater 5.

In this embodiment, the heating temperature of the heating cylinder 4 is automatically corrected only by inputting the average molecular weight of the molding resin used for molding, and the heating temperature is adjusted to a temperature corresponding to the molding resin. The cylinder 4 can be controlled. Therefore, even when the molding resin changes, the heating cylinder 4 can be automatically corrected to the optimal heating temperature of the molding resin. Therefore, the labor of the operator can be reduced, and the operator does not make an erroneous input.

In this embodiment, the average molecular weight is used as the resin characteristic value, but the melt index of the resin may be used.

(Embodiment 2) In this embodiment, the temperature of the heating cylinder 4 is controlled based on the relational expression stored in the arithmetic unit 7 of the controller 3. The relational expression is an expression relating to the resin characteristic value and the cylinder temperature. In this embodiment, the relational expression shown in Expression 1 is input to the calculation unit 7.

Tm = T0 + C (MI-M0) Equation 1 In Equation 1, Tm is a target temperature of the heating cylinder 4, Tm
0 indicates a reference heating cylinder temperature, C indicates a correction coefficient, MI indicates a resin characteristic value of a molding resin, and M0 indicates a reference resin characteristic value. In this embodiment, the melt index of the resin is used as the resin characteristic value.

Also in this embodiment, before starting the molding of the resin, the operator inputs the melt index MI of the molding resin used for molding into the input device 2. The input average molecular weight M is output to the calculation unit 7, whereby the calculation unit 7 calculates the temperature target value Tm of the heating cylinder 4 based on the stored equation (1). Calculated target value Tm
Is output to the temperature control unit 8, and the temperature control unit 8 controls the heater 5 so that the temperature of the heating cylinder 4 becomes the target value Tm. This control can be performed, for example, by controlling the current supplied to the heater 5.

In this embodiment, the heating temperature of the heating cylinder 4 is automatically corrected only by inputting the melt index of the molding resin used for molding, and the heating temperature is adjusted to a temperature corresponding to the molding resin. The cylinder 4 can be controlled. Therefore, even when the molding resin changes, the heating cylinder 4 can be automatically corrected to the optimal heating temperature of the molding resin. Therefore, the labor of the operator can be reduced, and the operator does not make an erroneous input. In particular, in this embodiment, since the target value of the temperature is calculated from the relational expression, there is no need to input the correspondence table 20 having a large number of values as in the first embodiment to the arithmetic unit 7. Can be done easily.

Although the melt index is used as the resin characteristic value in this embodiment, the average molecular weight of the resin may be used.

[0026]

According to the first aspect of the present invention, the optimum cylinder temperature of the heating cylinder is automatically selected by inputting the resin characteristic value of the molding resin to control the heating heater. The temperature of the cylinder can be automatically corrected, so that the labor of the operator can be reduced and erroneous input can be prevented.

According to the second aspect of the present invention, since the optimum cylinder temperature for the molding resin is calculated from the stored relational expression to control the heating heater, the temperature of the heating cylinder can be automatically corrected. It is possible to reduce the labor of the operator and prevent erroneous input.

According to the third aspect of the invention, in addition to having the same effects as the second aspect, the heating temperature of the heating cylinder can be accurately calculated.

According to the fourth aspect of the present invention, in addition to the effects of the first to third aspects of the present invention, it is possible to favorably perform temperature control according to the molding resin.

[Brief description of the drawings]

FIG. 1 is a front view of an injection molding apparatus to which the present invention is applied.

FIG. 2 is a front view of a correspondence table.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection molding apparatus 2 Input device 3 Controller 4 Heating cylinder 5 Heater

Claims (4)

[Claims] A heater for heating a heating cylinder;
An input device in which the resin characteristic value of the molding resin used for injection molding is input, and a cylinder temperature corresponding to the resin characteristic value is stored, and based on the resin characteristic value of the molding resin input from the input device. An injection molding apparatus, comprising: a controller that selects a cylinder temperature and controls the heater using the selected cylinder temperature as a target value for temperature control. 2. A heater for heating a heating cylinder,
An input device into which the resin characteristic value of the molding resin used for injection molding is input, and a relational expression between the resin characteristic value and the cylinder temperature are stored, and the resin characteristic value of the molding resin input from the input device is stored. An injection molding apparatus comprising: a controller that calculates a cylinder temperature based on an equation and a relational expression, and controls the heater by using the calculated cylinder temperature as a target value of temperature control. 3. The relational expression is: Tm = T0 + C, where Tm is the target temperature of the heating cylinder, T0 is the reference heating cylinder temperature, C is the correction coefficient, MI is the resin characteristic value, and M0 is the reference resin characteristic value. 3. The injection molding apparatus according to claim 2, wherein (MI-M0). 4. The resin characteristic value is an average molecular weight or a melt index.
An injection molding apparatus according to any one of the above.