JPS6410328B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for preventing a drive motor from idling when processing of a plastic molding machine is interrupted. Generally, among the above-mentioned molding machines, the function of an injection molding machine, for example, is to drive a hydraulic cylinder and an oil motor by operating a hydraulic pump, but recent injection molded products require high precision. It is not uncommon for an error of 1/100th of a millimeter to be unacceptable. Therefore, because it is necessary to keep all conditions constant at all times, the hydraulic pump is run idly, not only during short breaks due to physiological demands during work, but also during relatively long interruptions such as meal breaks. The temperature of the hydraulic oil is maintained at a constant temperature using frictional heat. The cooling water also prevents the temperature of the hydraulic oil from dropping abnormally due to idle operation of the hydraulic pump. Therefore, there was a large amount of power loss due to idle running of the drive motor. On the other hand, if the drive motor is stopped when the molding process is interrupted to eliminate the power loss mentioned above, the oil temperature will drop rapidly due to the flow of cooling water. It was not possible to perform molding processing, and it took a considerable amount of time for so-called warming up. Moreover, there is a large temperature difference between the oil temperature before machining is interrupted and the oil temperature after machining is resumed, which has a subtle effect on machining accuracy and becomes an obstacle to high-precision machining. The present invention is provided in order to solve the above-mentioned conventional problems, and includes a timer linked to an electric signal and other electric signals transmitted by the mold clamping mechanism section of the molding machine when the mold is opened, and the molding machine When processing has been interrupted for more than a set time, the molding machine drive motor is stopped by a timer or other power-cutting device, and an oil cooler is installed to cool the hydraulic drive section and a cooling device is installed to cool the mold section. The gist of the present invention is to prevent abnormal drops in the temperature of the hydraulic oil of the hydraulic drive unit and the temperature of the mold part by blocking the flow of cooling water using a solenoid valve attached to the water supply pipe. Embodiments of the present invention will be described below with reference to the drawings. Reference numeral 1 indicates an injection molding machine, which is roughly divided into a frame 2, an injection mechanism section 3, a mold clamping mechanism section 4, a hydraulic mechanism section 5, and an electric control section 6. It's on. The injection mechanism section 3 further includes a hopper 31, a material supply mechanism 32, a heating cylinder 33, a nozzle 34,
It is composed of an injection ram cylinder 35, etc. In addition, the mold clamping mechanism section 4 includes a fixed die plate 41
Then, molds 43 and 44 are placed on the movable die plate 42, respectively.
is attached, and is further provided with a tie bar 45, a mold clamping cylinder 46, a protruding device 47, a safety door (not shown), and the like. Furthermore, the hydraulic drive unit 5 includes a hydraulic pump 51 that operates the cylinder 35 of the injection mechanism, the cylinder 46 of the mold clamping mechanism, etc., and other control parts such as a pressure control valve, a direction switching valve, a flow rate control valve, etc. that are omitted in the figure. , oil pan 5
2, hydraulic piping 53, etc. The electric control section 6 includes a heating control section that adjusts the cylinder and nozzle temperatures, and a limit switch, timer, relay, etc. that controls the operations of the mold clamping mechanism and the injection mechanism. In the figure, 7 indicates a cooling water supply pipe, and the pipe 7 ₁ to the injection mechanism side is piped to a cooling tower 8 or a well, water supply or other water supply source, and the pipe 7 ₂ to the mold side has a water temperature Set the temperature (e.g. around 18℃)
An electric refrigerator 9 is installed to maintain the temperature. Each of the supply pipes 7 ₁ and 7 ₂ is provided with a solenoid valve 73 connected to the drive motor M.
10 is an oil cooler that cools the hydraulic oil of the hydraulic pump 51, _P1 is a pump operation switch, _P2 is a pump stop switch, _P3 is a pump emergency stop switch, MR is a motor relay, MS is a magnetic switch, R is the lamp, SW is the selection switch, Bc
indicates a B contact, MRs indicates a motor stop relay, MRsi indicates a motor stop amplification section, and _4'1 indicates a mold opening/closing section of the mold clamping mechanism section 4. Next, the operation of the present invention will be explained. In the normal injection molding process, the hopper 31 in FIG.
The pellets (resin material) introduced into the mold are sent forward through the heating cylinder 33 while being heated by the rotation and extrusion of the screw ₃₅₁ , and after being sufficiently melted, the pellets are sent from the nozzle 34 to the mold clamping mechanism in advance. It is then injected into the closed molds 43, 44. The molded product cooled and solidified within the mold is then taken out by opening the mold. The empty mold is then closed and injection begins again. However, in the process, the molds 43, 44
In principle, the opening time of the mold is the minimum necessary to take out the cooled and solidified molded product, but if the molded product is not taken out or the safety door does not close for some reason, the mold will not close. The next injection molding cannot be performed. In this case as well, the motor M is naturally in the driving state. In the present invention, as described above, the timer 11 is linked to the electric signal transmitted when the molds 43, 44 are opened, the safety door is opened, and the electric signal transmitted when a molding process is completed. , molds 43, 44 for a set period of time (for example, 1 to 3 minutes)
If the molding process continues to be interrupted due to, for example, opening of the motor, the motor stop relay MR is activated by the action of the timer 11, and the drive of the motor M is further stopped via the motor stop relay amplifier _MR1 .
As a result, the hydraulic pump 51 also stops, and the injection mechanism section 3 stops. Since the electromagnetic valves 73 of the cooling water supply pipes 7 ₁ and 7 ₂ are closed by stopping the motor, the supply of cooling water to the oil cooler 10 and the molds 43 and 44 is cut off. When restarting the molding process, the switch must be turned on.
When the SW is turned on, the motor M is driven, the hydraulic pump 51 is operated, and at the same time, the solenoid valve 73 is opened and cooling water flows. Furthermore, when the temperature of the hydraulic oil or the temperature of the mold section falls below a set value due to the motor drive being stopped, it is also possible to turn on the selection switch SW which drives the motor M by the action of the thermostat T. be. [Example 1] In the summer, when the motor drive was stopped for one hour at a temperature of 28°C, the oil temperature, which was normally 45°C, decreased by about 1.3°C, and in the winter, when the temperature was about 8°C, the oil temperature decreased by about 4°C. , there is no change in conditions if the temperature decreases within 6°C. The table below shows the results obtained when the product was installed on 11 injection molding machines, excluding molding machines capable of automatic molding.

【table】

[Table] As shown in the table above, data collection and analysis for 1 month on 11 injection molding machines resulted in a total savings of 2 hours and 5 minutes (86.2%) in idle running time per day.
We were able to save 13.61KW (86.2%) in electricity. Since the present invention has the above-mentioned configuration, when there is a relatively long processing interruption due to a short break during work or a meal break, the timer 11, which is set to a short time of 1 to 3 minutes, is activated and the motor M At the same time, the supply of hydraulic oil and cooling water to the mold section is also cut off, so even if the injection mechanism section 3 and the mold clamping mechanism section 4 stop driving, the heating temperature necessary for molding can be maintained. Abnormalities or significant temperature drops can be prevented. Therefore, even when the motor drive power is turned on and processing operations are resumed, the temperature required for forming operations is restored in an extremely short period of time. Further, when the molding process is interrupted after the time set by the timer 11 has elapsed, the drive of the motor M is automatically stopped, so that the power loss required for driving the motor is significantly reduced. Furthermore, the load on the cooling tower 8 and the refrigerator 9 is eliminated, and the consumption of cooling water can also be reduced.

[Brief explanation of the drawing]

The drawings show an embodiment of the method of preventing the drive motor from idling when processing is interrupted in a molding machine according to the present invention, and FIG. 1 is a partially longitudinal front view of the injection molding machine, and FIG. 2 is a schematic diagram of the operating circuit. shows. DESCRIPTION OF SYMBOLS 1... Injection molding machine, 2... Frame, 3... Injection mechanism section, 4... Mold clamping mechanism section, 5... Hydraulic mechanism section, 6... Electric control section, 7... Cooling water supply pipe, 1
0... Oil cooler, 73... Solenoid valve, M...
Drive motor.

Claims (1)

[Claims] 1. A timer is linked to the electric signal that the mold clamping mechanism of the molding machine sends when opening and closing the mold and other electric signals, and when the molding machine has been interrupted for a set time or more, the molding machine starts operating. The motor is stopped by the operation of a timer or other current-cutting device, and the cooling water is circulated by an oil cooler for cooling the hydraulic drive unit and a solenoid valve installed in the cooling water supply pipe for cooling the mold part. A method for preventing idling of a drive motor during interruption of processing in a molding machine, characterized in that the temperature of the hydraulic oil in the hydraulic drive unit and the temperature of the mold part are prevented from abnormally decreasing.