JPS59209468A - Controlling method of molding in injection molding machine - Google Patents

Abstract

PURPOSE:To detect generation of a defective molding during operation and to improve workability by measuring the time since a melt is injected at a high speed into a metallic mold until a gas vent valve is automatically closed and comparing the same with the preset control time. CONSTITUTION:When a molten metal is supplied into a die cavity 4 and is filled therein, a gas vent valve 13 is closed as its valve 15 contacts tightly a valve seat 14a. A detaining bar 19 moves to actuate a sensor 20, the signal from which is inputted as the closing time of the valve 13 to a measuring device 29. The device 29 measures a measuring time Tm from the signal for starting the high speed injection and the closing signal of the valve 13. The time Tm is compared with the control time Ts which is preset by a control time setter 30 in a comparator 31 and if the former Tm is within the latter control time Ts, the absence of a defective molding is judged and an alarm device 32 is not operated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding control method for determining defective molded products in an injection molding apparatus.

Injection molding equipment such as die casting equipment is equipped with a gas vent valve in the mold, and while the gas in the mold is extracted from this gas vent valve, the pressure of the molten metal injected into the mold is controlled by the gas vent valve. The valve is automatically closed. At this time, if gas remains in the mold without being released, cavities may be formed in the molded product or a portion of the molded product may be missing.

For this reason, generally, the gas is forcibly removed by a vacuum generator at the same time as the injection of molten metal is started, to prevent the occurrence of defective molded products as described above. However, when an injection molding machine is operated for a long time, the movement of the injection plunger becomes unsmooth and the injection speed changes, or the water remaining in the mold turns into steam, causing the mold to leak out. The exhaust gas becomes insufficient, resulting in the above-mentioned defective molded products.

In the past, the occurrence of such defective molded products could only be detected after the molded product was taken out after injection molding or when it was further inspected, and it was impossible to detect it during the injection molding process. .

In view of the above-mentioned problems, an object of the present invention is to provide a molding control method in an injection molding apparatus that can immediately detect the occurrence of defective molded products during injection molding operations and improve work efficiency. be.

The method of the present invention for achieving the above object is an injection molding apparatus in which a mold is provided with a gas vent valve, and the gas vent valve is automatically closed by the pressure of the melt injected into the mold.
Molding is carried out by measuring the time from the start of high-speed injection of the molten material into the mold until the automatic closing of the gas vent valve, and comparing the measured time with a preset control time to detect the time difference. It is characterized by determining the quality of the product.

The idea of the present invention is that the closing timing of the degassing valve changes from the initial compaction timing due to changes in the injection speed due to long-term operation of the injection molding machine, generation of water vapor due to residual water in the mold, etc. It was discovered that this change resulted in insufficient gas discharge within the mold. and,
Based on this knowledge, the actual closing timing of the gas vent valve during injection molding work can be compared with the control time initially set by calculation etc. in advance, and by detecting the presence or absence of a difference in time, injection molding work can be performed. This makes it possible to immediately detect the occurrence of defective molded products even in the middle of the process.

Hereinafter, the present invention will be explained along with an injection molding apparatus for aluminum molded products.

In the figure, 1 is a mold, a fixed mold 2 and a movable mold 3.
and a mold cavity 4 on the abutting surface of both.
is formed. An injection sleeve 5 is attached to the fixed mold 2, and a supply port 5a for supplying molten aluminum is provided at the end thereof. A head 6a of an injection plunger 6 is fitted into the injection sleeve 5 so as to be able to reciprocate.

The injection plunger 6 is driven by a hydraulic cylinder 7 to inject the molten metal within the injection sleeve 5 into the mold cavity 4. A striker 8 is fixed to the injection plunger 6, and the striker 8 is connected to a plurality of glue switches 9. ．． 10, 11, and 12, and when in contact, these are turned off, and when they reciprocate together with the injection plunger 6 and the rear end 8a comes off, they are turned on. Among these, limit switches 9 and 12 are used to set the forward limit and backward limit of the injection plunger 6, respectively, and 11 commands a signal to start operation of a vacuum pump 26, which will be described later, to force gas from the mold cavity 4. 1o is a signal to start high-speed injection of molten metal into the mold cavity 4.

A gas vent valve 1 is provided on the abutting surface of the fixed mold 2 and the movable mold 3 facing the gas exhaust passage 4a leading to the mold cavity 4.
3 is a provision. This gas vent valve 13 has a valve seat 1.4
The valve 15 includes a fixed spool 14 having a lower end a, and a valve 15 into which a valve stem 15a is slidably fitted into the fixed spool 14. The fixed spool 14 fits into a hole formed in the abutting surfaces of the fixed mold 2 and the movable mold 3, and the valve J5
The upper end of 5a is pressed by a compression spring 16, and is urged to close the gas exhaust path 4a at all times. As shown in detail in FIG. 2, the stepped part in the middle of the valve stem 15a has a
A locking rod 19 is biased by a compression spring 18 and presses a ball 17 interposed at its tip. When the valve 15 is pushed up by the pressure of the molten metal and closes the valve seat 14a, the stepped portion of the valve stem 15a pushes the locking rod 19 to the right in the figure, actuating the sensor 2o, and closing the valve. Detect valve.

A bypass passage (not shown) for gas exhaust is provided between the middle of the gas exhaust passage 4a and a position immediately in front of the valve seat 14a. In addition, an exhaust path 2 is provided on the side of the fixed spool 14.
1 is provided, and this exhaust path 21 is connected to a filter 23 via a pipe 22, and further to a vacuum tank 2 via a solenoid valve 24.
5 and a vacuum pump 26 are connected. In addition, the piping 22
A pipe 22a branches off from the middle, and is connected to a pressure pump 28 via a solenoid valve 27.

29 is a measuring instrument. This measuring device 29 receives a high-speed injection start signal of molten metal from the limit switch 10 and a sensor 2.
The automatic valve closing signal of the gas vent valve 13 from 0 is input, and the time Tm that has passed between both signals is measured. Reference numeral 30 denotes a control time setting device, which calculates in advance the elapsed time from the start of the high-speed injection to the automatic closing of the gas vent valve to prevent the occurrence of defective injection molded products, and sets this as the control time Ts.

This management time Ts is generally set as a time having a certain range Tsl=Tsu consisting of an upper limit time Tsu and a lower limit time Tsl.

This control time Ts is set appropriately depending on the type of melt to be injection molded, temperature, capacity of the mold cavity, injection speed, etc. 31 is a comparator, and the above measurement time T
m and the management time Ts, and output the result to the alarm device 32. The alarm device 32 issues an alarm when the measured time Tm is outside the management time Ts, but does not issue an alarm when it is within the management time Ts.

Now, when performing injection molding using the above-mentioned apparatus, first, in the state shown in FIG. let When the rear end 8a of the striker 8 passes the limit switch 11 due to this forward movement, the switch 11 is turned on, and the solenoid valve 2
Open the valve 4 and operate the vacuum pump 26°. By operating the vacuum pump 26, gas is started to be removed from the mold cavity 4, resulting in a reduced pressure state. Next, when the rear end 8a of the striker 8 passes the limit switch 10, the switch 10 is turned on from the moment of passing, increasing the amount of hydraulic fluid to the hydraulic cylinder 7, and increasing the amount of hydraulic fluid to the injection plunger 6.
is accelerated and starts high-speed injection.

At the same time, a signal from the switch 10 is input to the measuring device 29 as the high speed injection start time.

When the molten metal is supplied to the mold cavity 4, the gas remaining in the mold cavity 4 is pushed by the molten metal, and the gas vent valve 13
and is discharged to the exhaust passage 21. When the mold cavity 4 is filled with molten metal, the second valve 15 of the gas vent valve 13 is opened.
The valve is pushed up as shown by the chain line in the figure, and is brought into close contact with the valve seat 14a to close the valve. Due to this automatic valve closing operation, the locking rod 19 moves as shown by the chain line, and the sensor 20 is activated. sensor 2
A signal of 0 is detected by the measuring device 29 as the closing time of the gas vent valve 13.
is input.

The measuring device 29 receives the above-mentioned high-speed injection start signal and the gas vent valve 13.
The measurement time Tm is measured from the closing signal. This measurement time Tm is determined by the comparator 31 as the management time T s (T s u ” T
s 1 ), and the former Tm is compared with the latter management time T
If it is within s, it is assumed that no defective molded products have occurred and alarm 3 is activated.
2 does not work.

However, if the former Tm is shorter than the latter Ts, the alarm 32 issues an alarm because the timing of closing the gas vent valve 13 is too early and a defective molded product is generated due to residual gas, and the former Tm is shorter than the latter Ts. If it exceeds the limit, or if the variation in the time difference is too large, the alarm 32 issues an alarm indicating that an abnormality has occurred in the gas vent valve 13 or in the injection system, and the injection molding operation is stopped. Therefore, the occurrence of defective molded products can be immediately detected during injection molding operations, and work efficiency can be improved.

In the above embodiments, injection molding of aluminum has been described, but the present invention is also applicable to injection molding of metals other than aluminum, plastics, etc.

As described above, the present invention provides an injection molding apparatus in which a mold is provided with a gas vent valve, and the gas vent valve is automatically closed by the pressure of the melt injected into the mold. The quality of the molded product is determined by measuring the time from the start of high-speed injection of the molten material until the automatic closing of the gas vent valve, and comparing the measured time with a preset control time to detect the time difference. Therefore, the occurrence of defective molded products can be immediately detected during injection molding operation, and work efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic partially cross-sectional view of an apparatus for implementing the present invention, and FIG. 2 is an enlarged schematic view showing a gas vent valve portion of the apparatus in cross-section. 1. Mold, 4. Mold cavity, 6. Injection plunger, 8. Striker, 10.11.
Riminotosinch, 13. Gas vent valve, 15.
・Valve, 19..Latching rod, 20..Sensor, 26.
・Vacuum pump, 29... Measuring device, 30... Management time setting device, 31... Comparator, 32... Alarm device. Agent: Patent Attorney Shin Ogawa - Patent Attorney Ken Noguchi Teru Patent Attorney Kazuhiko Saishita Figure 1 Figure 2

Claims (1)

[Claims] In an injection molding apparatus in which a mold is provided with a gas vent valve and the gas vent valve is automatically closed by the pressure of the molten material injected into the mold, high-speed injection of the molten material into the mold is started. The injection method is characterized in that the time from when the degassing valve automatically closes is measured, and the measured time is compared with a preset control time to detect a time difference to determine the quality of the molded product. Molding control method in molding equipment.