JPH0659746A - Hydraulic system - Google Patents

Abstract

PURPOSE:To provide a hydraulic system in which the actuations of desired pressure and speed can be performed even when the temperature of fluid changes. CONSTITUTION:The same actuations as at the time of setting of actuating conditions can be performed even when the temperature of fluid changes from the temperature of fluid at the time of setting of the actuating conditions, by storing the temperature of fluid at the time of setting of the actuating conditions, for instance, at the time of setting of the forming conditions such as the pressure and speed in a forming machine as a reference temperature in a reference temperature storage part 21, by preliminarily storing the characteristic data such as viscosity change for the temperature of fluid in a characteristic data storage part 22 and adding a correction to the control output from an output part 20 based on the temperature difference between the temperature of fluid detected by a temperature sensor 17 and the reference temperature and the characteristic data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic system utilizing hydraulic pressure such as various molding machines for plastics and rubbers or industrial robots, and more particularly to control of pressure and flow rate thereof.

[0002]

2. Description of the Related Art In a hydraulic device of this type, for example, a hydraulic injection molding machine, the pressure and speed of the mold opening and closing process and the injection process are controlled by controlling the pressure and flow rate of hydraulic oil. It is being appreciated.

[0003]

In such an injection molding machine, an operator first performs a trial run to set molding conditions such as pressure and speed at which a desired molded product is obtained, and under such molding conditions, a full-scale operation is performed. Molding starts, but since the viscosity of hydraulic oil changes with temperature, if the temperature of hydraulic oil changes significantly from the temperature when the molding conditions were set, the pressure and temperature of molding will have an effect. Will receive
It becomes difficult to obtain a desired molded product.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a hydraulic device capable of operating at a desired pressure and speed even if the temperature of hydraulic oil changes. And

[0005]

In order to achieve the above-mentioned object, the present invention is constructed as follows.

That is, the present invention comprises a setting unit for setting an operating condition corresponding to a desired operation, and an output unit for providing a control output according to the set operating condition, and based on the control output, In a hydraulic device that controls at least one of the pressure and flow rate of hydraulic oil so as to perform the desired operation, a temperature sensor that detects the temperature of the hydraulic oil and the temperature of the hydraulic oil when the operating condition is set. Is stored as a reference temperature, a characteristic data storage unit in which characteristic data of the hydraulic oil is stored in advance, and a temperature difference between the temperature of the hydraulic oil detected by the temperature sensor and the reference temperature. , And a correction unit that corrects the control output from the output unit based on the characteristic data, and at least one of the pressure and the flow rate of the hydraulic oil from the hydraulic pump according to the corrected control output. And a control valve for controlling.

[0007]

According to the above construction, when the operating conditions are set, for example, the temperature of the hydraulic oil when setting the molding conditions such as pressure and speed in the molding machine is stored as a reference temperature, and the viscosity of the hydraulic oil with respect to the temperature is stored. Characteristic data such as changes are stored in advance, and the control output is corrected based on the temperature difference between the temperature of the hydraulic oil detected by the temperature sensor and the reference temperature, and the characteristic data. Even if the temperature changes from the temperature of the hydraulic oil when the operating condition is set, the temperature is corrected accordingly, and the same operation as when the operating condition is set can be performed.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention. In this embodiment, description will be made by applying it to a hydraulic injection molding machine.

In the figure, 1 is a mold, 2 is a mold position detecting encoder, 3 is a mold clamping cylinder for opening and closing the mold 1,
4 is a nozzle, 5 is a screw, 6 is a hopper for supplying the material, 7 is a heater for heating and melting the material in the cylinder 8, 9 is an encoder for detecting the screw position, 10 is an injection cylinder for moving the screw 5, 11 Is a hydraulic motor for rotating the screw 1, 12 and 13 are mold moving valves and screw moving valves for switching the hydraulic path between the mold moving and the screw moving, and 14 is the hydraulic oil from the hydraulic pump 15. A flow rate control valve that controls the flow rate, 16 a pressure control valve that controls the pressure of hydraulic oil from the hydraulic pump 15, 17 a temperature sensor that detects the temperature of hydraulic oil, and 18 a setting unit for setting molding conditions and the like. ,
19 is the set molding conditions and the above-mentioned encoder 2,
The molding machine unit gives a control output to the control valves 14, 16 and the like based on the output of 9 or the like.

Similarly to the conventional example, the molding machine unit 19 of this embodiment, when the molding conditions such as the mold clamping force and the mold clamping speed are set by the setting section 18, the control output corresponding to the molding conditions is set. Flow control valve 14 and pressure control valve 16
And the like, and the opening / closing process and the injection process of the mold 1 are thereby performed.

For example, FIG. 2 shows changes in the mold clamping speed and the mold clamping pressure in the mold closing process and the outline of the molding machine, and FIG. 3 shows changes in the injection speed and injection pressure in the injection process and the molding machine. Shows the general situation of.

In the mold closing step, the flow rate control valve 14 and the pressure control are performed so that the mold clamping speed and the mold clamping pressure change stepwise according to the position of the mold, as shown in FIG. 2 (a). The valve 16 is controlled, and in the injection process, the injection speed and the injection pressure are changed stepwise according to the position of the screw and the timer output, for example, as shown in FIG. 14 and pressure control valve 16 are controlled.

When the molding conditions are set in this way,
The point that the control output corresponding to the molding conditions is given to the flow rate control valve 14 and the pressure control valve 16 to control the speed and pressure is the same as in the conventional example.

In this embodiment, even when the temperature of the hydraulic oil changes from the temperature when the molding conditions are set,
As in the case where the molding conditions are set, the following structure is provided so that a desired molded product can be stably obtained.

That is, FIG. 4 is a functional block diagram of this embodiment, and the portions corresponding to those in FIG. 1 are designated by the same reference numerals.

The molding machine unit 19 of this embodiment includes an output section 20 for giving a control output according to the molding condition set by the setting section 18 in the same manner as the conventional one, and a temperature of hydraulic oil when the molding condition is set. Is stored as a reference temperature, and a characteristic data storage unit 22 in which characteristic data indicating a viscosity change with respect to a temperature change of hydraulic oil is stored in advance.
Based on the temperature difference between the hydraulic oil temperature detected by the temperature sensor 17 and the reference temperature, and the characteristic data,
A correction unit 23 for correcting the control output from the output unit 20 is provided, and the control output corrected by the correction unit 23 is applied to the flow rate control valve 14 and the pressure control valve 16 described above. .

The correction unit 23 corrects the molding conditions when the temperature difference between the hydraulic oil temperature when the molding conditions are set and the current hydraulic oil temperature does not affect the molding conditions. Therefore, when there is no temperature difference, the control output from the output unit 20, that is, the control output similar to the conventional one is output as it is.

The correction by the correction unit 23 is carried out based on an experimental result and the like in advance by conducting an experiment or the like.

As described above, when there is a temperature difference between the temperature of the hydraulic oil at the time of setting the molding conditions and the current temperature of the hydraulic oil, the correction output is corrected by the correction unit 23, so that the influence of the temperature difference is exerted. To avoid receiving
Since the same operation can be performed as when the molding condition is set, a desired molded product can be stably molded as in the case where the molding condition is set.

Although the above-described embodiments have been described by being applied to the injection molding machine, the present invention can be similarly applied to other machine tools utilizing hydraulic pressure, industrial robots, and the like.

[0022]

As described above, according to the present invention, the temperature of hydraulic oil is stored as the reference temperature when the operating conditions are set, for example, when the molding conditions such as pressure and speed in the molding machine are set. Characteristic data such as viscosity change with respect to the temperature of hydraulic oil is stored in advance, and the control output is corrected based on the temperature difference between the hydraulic oil temperature detected by a temperature sensor and the reference temperature, and the characteristic data. Therefore, even if the temperature of the hydraulic oil changes from the temperature of the hydraulic oil when the operating condition is set, the temperature is corrected by that amount, and the same operation as when the operating condition is set can be performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a mold closing process.

FIG. 3 is an explanatory diagram of an injection process.

FIG. 4 is a functional block diagram of the embodiment shown in FIG.

[Explanation of symbols]

 14 flow rate control valve 15 hydraulic pump 16 pressure control valve 17 temperature sensor 18 setting unit 20 output unit 21 reference temperature storage unit 22 characteristic data storage unit 23 correction unit

Claims (1)

[Claims] 1. A setting unit, in which an operating condition corresponding to a desired operation is set, and an output unit, which gives a control output according to the set operating condition, and the desired operation is based on the control output. In the hydraulic device that controls at least one of the pressure and the flow rate of the hydraulic oil, a temperature sensor that detects the temperature of the hydraulic oil, and the temperature of the hydraulic oil when the operating condition is set to a reference temperature. A reference temperature storage unit, the characteristic data of the hydraulic oil, a characteristic data storage unit that is stored in advance, a temperature difference between the hydraulic oil temperature detected by the temperature sensor and the reference temperature, and the characteristic A correction unit that corrects the control output from the output unit based on the data, and a control that controls at least one of the pressure and the flow rate of the hydraulic oil from the hydraulic pump according to the corrected control output. Hydraulic apparatus comprising: a and.