JPS6233050A - Method for ejecting injection product at mold opening of injection molding machine - Google Patents

Abstract

PURPOSE:To improve mass productivity by synchronizing the displacement of an injection cylinder for ejecting a biscuit and the opening displacement of a movable mold so that the advance speed of a plunger tip is made coincident with the retreat speed of the mold. CONSTITUTION:A mold opening displacement detector 41 is provided to a movable platen 17 and an injection displacement detector 42 is provided to an injection plunger 24 to control an injection speed control valve 50. The advance distance of the plunger tip 22 detected by the detector 42 is fed back and is inputted to a differential amplifier which controls the valve 50 by the difference between the output of the detector 41 and the output of the detector 42. The displacement of the plunger trip 22 and the displacement of the movable mold 13 are synchronized by such method. The crushing of the biscuit in the mold opening stage is thus obviated and since chill time is shortened, the mass productivity of the product is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a cast product using an injection molding device such as a die casting machine, and more specifically, a method for manufacturing a cast product using an injection molding device such as a die casting machine. This relates to an ejection method.

[Prior Art] In general, the production of cast products by injection molding uses an injection molding apparatus as shown in FIG. Press fit into a cavity 15 formed between a mold 11 consisting of a fixed mold 12 and a movable mold 13,
After the molten metal filled into the cavity 15 is cooled and solidified to form the product 27, the movable mold 13 is moved back together with the movable platen 17 to open the mold. After taking out the product 27 and cleaning the mold 11 and applying a mold release agent, the movable mold 13 and the fixed mold 12 are clamped together, and the molten metal is again press-filled into the cavity 15. Repeat injection molding.

By the way, in order to increase mass productivity in the above injection molding,
Various attempts have been made to shorten the cycle time from press-fitting the molten metal to mold clamping in preparation for the next press-fit.

TefrXJI-)h1SelfI/1%4>diIJWzW1. c) In order to shorten the chill time during the solidification process, the shapes of the fixed mold 12, movable mold 13 and cavity 15 have been devised. Efforts have been made to improve the efficiency of cleaning and applying 41 kg of molding agent.

[Problems to be Solved by the Invention] As mentioned above, attempts have been made to shorten the cycle time by shortening the chill time, which is the period during which the molten metal is cooled, and by shortening the time in processes such as mold opening, cleaning, and mold clamping. In shortening the chill time, if the chill time is too short, the cooling and solidification of the molten metal will be insufficient, and the product will be deformed in the step of taking out the product from the hinged mold 13, as well as in the cooling and loading steps after taking out. Moreover, when opening the mold, as shown in FIG.
However, at this time, the biscuit 29 breaks and the molten metal inside is scattered, which is not only dangerous, but also has the disadvantage that the scattered molten metal adheres to the mating surface of the mold 11, making subsequent casting difficult.

In many cases, it takes a long time to cool the remaining hot water that is filled into the cavity 15 in the mold 11 and forms the biscuit 29, which is a thicker part or a larger lump than the molten metal that forms the product 27. In order to prevent the biscuit 29 from breaking when the mold is opened, it is necessary to lengthen the chill time until the molten metal of the biscuit 29 parts is completely solidified, which results in a longer cycle time.

The present invention eliminates such drawbacks and is a method of opening the mold without breaking the biscuit 29 whose inside is not solidified at the time of opening the mold.The present invention opens the mold when the outer periphery of the biscuit 29 has solidified, thus reducing the chill time and the time. This is a mold opening method that shortens casting cycle time and increases mass productivity.

[Means for Solving the Problem] In injection molding, after the required time for injecting molten metal into a cavity and cooling the cast product in the mold, when opening the mold to take out the cast product, the fixed The displacement of the injection cylinder that ejects the biscuit in the mold is synchronized with the displacement of the movable mold when the mold is opened, so that the forward speed of the plunger tip and the backward speed of the movable mold are made constant. This is a characteristic method for ejecting an injected product when opening a mold in an injection molding apparatus.

[Function] In the present invention, when extruding biscuits from a fixed mold, the advancing speed of the plunger tip for extruding the biscuit is made equal to the trailing speed of the movable mold by synchronizing it with the backward speed of the movable mold. The biscuits sandwiched between the movable molds can be extruded from the fixed mold without being crushed by the plunger chip.

Therefore, even if the molten metal inside the biscuit is not solidified, the outer periphery of the biscuit is cooled and solidified, of course.

When the product inside the cavity is cooled and solidified, the mold can be opened easily, and the chill time can be shortened.

[Example] As an apparatus for carrying out the method of the present invention, for example, in FIG. 1, 11 is a mold consisting of a fixed mold 12 and a movable mold 13, 15 is a cavity of the mold 11, and IB is a fixed platen. ,
17 is a movable platen, 18 is a link housing, 19 is a toggle mechanism, 20 is a mold clamping cylinder, 14 is a machine base, 9
is the column, IO is the column nut, 21 is the injection sleeve,
22 is a plunger chip, 24 is an injection plunger, 25
is the injection cylinder.

A mold opening displacement detector 41 is provided for the movable member 5117, and an injection displacement detector 42 is also provided for the injection plunger 24, and the injection speed control valve 50 is controlled by a feedback control system as shown in FIG.

That is, as shown in FIG. 1, the mold opening displacement detector 41 is movable f! A striker 31 is integrally attached to the striker 31, and the striker 31 is provided with an rt magnetic scale 32, and a magnetic detector 33 facing the magnetic scale 32 is provided, and the magnetic detector 33 detects the striker. 31, that is, the amount of retraction of the movable platen 17 and, by extension, the movable mold 13, can be detected.

In injection molding equipment, the mold 11 is often clamped by the mold clamping cylinder 20 and the toggle mechanism 19, and the toggle mechanism 19 is used to detect the mold 11.
As shown in Figure 3, when the opening and closing of the movable l! 1k17, that is, when the movable mold 13 is retracted, the retraction speed changes in a complicated manner depending on the retracted position, and this is to synchronize with the retraction of the ITr movable mold mold 13.

Further, for injection displacement detection, a striker 31 is integrally attached to the injection plunger 24 of the injection cylinder 25, and a magnetic detector 33 facing the magnetic scale 32 of the single-nuclear striker 31 is provided as the mold opening displacement detector 42. Same as 41. Note that this injection displacement detector 42 can also be used as a plunger position detector for controlling the injection speed when filling the cavity 15 with molten metal.

Then, the amount of retraction of the movable mold 13 detected by the above-mentioned mold opening displacement detector 41 is used as a target value for opening degree adjustment 1'' to the injection speed control valve 50, and the plunger tip 22 detected by the injection displacement detector 42 The state of advance is input to the differential amplifier 43 as a feedback signal, and the injection speed control valve 50 is controlled by the injection speed control device 44 based on the deviation between the output of the mold opening displacement detector 4I and the output of the injection displacement detector 42. death,
Thus, the displacement of the plunger tip 22 by the injection cylinder 25 is synchronized with the displacement caused by the opening of the movable mold 13.

By the way, although the forward speed of the injection plunger 24 when opening the mold is extremely low compared to the high speed forward speed of the injection plunger 24 when filling the cavity 15 with molten metal, the injection speed as shown in FIG. control valve 50
When using a single injection speed control valve f50, the speed can be controlled without using a separate flow-1 control valve for very low speed.

This injection speed control valve 50 has a structure as shown in FIG. A valve body 55 having an annular groove 54a for hydraulic oil outflow and a hydraulic oil outflow port 54 moves in the axial direction in the valve body 52, and has an axial through hole 55a inside near the outer peripheral surface. spool, 56 is a shaft integrally provided at the rear of spool 55, 58a is +i
Nand shaft, 5, which is integrally provided on the rear end side of l+57
Reference numeral 7 denotes a screw shaft screwed into the inner shaft center of the nut shaft 56a by a pole screw 58, 59 a joint connecting the screw shaft 57 and the shaft of the pulse motor 51, and 60 preventing rotation of the nut shaft 56a. This is a key that guides movement in the axial direction.

According to the rotation of the pulse motor 51, the spool 55
moves forward and backward in the axial direction to instantaneously open and close the valve and adjust the opening degree to control the flow rate. This injection speed control valve 5
As described above, the spool 55 is installed in the cylindrical valve body 52, which has the hydraulic oil inlet 53 on the axial end face and the side hydraulic oil outlet 54a, which is an annular groove.
is driven in the axial direction by the action of the pulse motor 51 to control the flow rate, and when the axial thrust of the spool 55 due to the hydraulic oil starts to move to a sudden position according to the increase in the opening amount and moving speed of the spool 55. When the spool 55 moves to the large opening position, a thrust force is applied in the valve opening direction so that the valve can be easily opened, and when the spool 55 has moved to the large opening position, a thrust force is applied in the valve closing direction so that the valve can be stopped quickly. By doing so, the driving force required for high-speed switching of the flow rate is reduced, and the switching time is also made extremely short, so that the performance of high-speed switching of the flow rate by the injection speed control valve 50 can be further improved and the driving force can be reduced. This is what I did.

In this injection speed control valve 50, the injection speed 1υ control device 4
The opening of the spool 55 is determined by the amount of rotation, that is, the angle of rotation of the pulse motor 51, and the flow rate to the injection cylinder 25 is controlled by the control pulse train from the control pulse generator built in the pulse motor 4. The rate of change of the flow (2), that is, the state of the speed, is determined by the magnitude of the rotational speed during the rotation of the valve 51.

In the injection speed control valve 50 having such a structure and operation, the spool 55 is actually adjusted in response to a speed change command.
The time it takes for the
wIIu, to: fwl-, 1t-11 17fl-2+
+Su-11zuV-=, compared to the normal flow rate control pulp of Lt, the responsiveness is extremely good, and the operability and operational accuracy of valve opening/closing etc. are also extremely good. In addition, the nut shaft 58a
A permanent magnet 61 is fixed to a part of the surface of the permanent magnet 6I and a part of the tJ direction/y-singing G2 is equipped with a magnetic position detector 6 called a zero cross sensor.
The 0 position detector 63 to which 3 is attached is composed of a proximity switch that is sensitive to the movement of the permanent magnet 61, and accurately detects the moving distance of the nut shaft 58a and spool 55 in the axial direction. Can give feedback. Also, the zero position t of the spool 55 is detected by the permanent magnet 61 and the position
The pulse motor 5 is electrically sensed by the action of A83 and is activated via a control pulse generator not shown in this figure.
1 can also be kept exactly at that position.

As the 1-position detector 83, one having an accuracy of 0.01 mm can be used. Therefore, by using such an injection speed control valve 50, it is possible not only to control the injection speed when filling the cavity 15 with molten metal, but also to accurately advance the plunger tip 22 at a low speed in accordance with the retreat of the movable mold 13. can also be controlled.

Of course, a flow rate control valve 48 similar to this injection speed control valve 50
can also be used in type 1v6 circuits. That is, in FIG. 1, 20 is a mold clamping cylinder for driving the torg mechanism attached to the link housing 18, 47 is a cutting valve for opening the mold clamping mold, and 48 is a flow rate capable of controlling the mold clamping mold opening speed. It is a control valve.

Then, the injection plunger 24 is advanced using such an injection speed control valve 50, and at this time, as described above, the movable mold 1
The injection speed control valve 5 is set so that the forward speed matches the retreat of step 3.
Since a small amount of pressure oil is sent to the injection cylinder 25 at 0, the biscuit 29 is not strongly pressurized by the movable mold 13 and the plunger tip 22, and even if the inside of the biscuit 29 is not solidified, the biscuit 29 is not solidified. If the outer periphery of No. 29 has solidified to some extent.

The biscuit 23 can be extruded from the injection sleeve 21 attached to the fixed mold 12 without pushing out the biscuit 29 completely.

In the above embodiment, the displacement of the movable mold 13 is detected magnetically and electrically to synchronize the advancement of the plunger tip 22 and the retreat of the movable mold 13, and on the other hand, the injection speed control valve 50
Plunger tip 2 operated by oil supply controlled by
Although the advance of the injection cylinder 25 is performed by feedback control using a feedback signal of an electric signal, in another embodiment, as shown in FIG.
There is also a method of synchronizing control based on oil pressure detection in order to keep the oil pressure sent to extremely low pressure.

In this embodiment, the injection pressure in the injection cylinder 25 is detected by the injection pressure detector 45 and compared with a low pressure set by the pushing force setting device 46 which is artificially set.
Controls 0.

In this case, when the retraction speed of the movable mold 13 becomes slow, the resistance force from the movable mold 13 inhibits the forward movement of the plunger tip 22 via the biscuit 29, and the hydraulic pressure of the injection cylinder 25 increases. When the set low pressure of the container 46 is reached, the injection speed control valve 5o is closed, and the forward movement of the plunger tip 22 is decelerated or stopped, and if the backward speed of the movable mold 13 is fast, the
a −已 ++ @ −/ ２ +7,
"3, 4 - -/QQM ',!'
I''&++c resistance becomes smaller, the opening degree of the injection speed control valve 50 is increased, the forward speed of the plunger tip 22 is increased, and the forward speed of the plunger tip 22 can be synchronized with the backward speed of the movable platen 17. It is.

For example, in an injection molding machine with a mold clamping force of 1850 t, the injection pressure of the molten metal is normally in the tens to hundreds of meters, but by making the setting pressure by the pressing force setting device 46 extremely small, such as 5 t, the plunger While the forward speed of the tip 22 is synchronized with the backward speed of the movable mold 13, the pressure on the biscuit 23 by the plunger tip 22 is made extremely small to a maximum of 5, thereby allowing the biscuit 29 to be removed from the injection sleeve 21 without being crushed. Extrusion is ti(
Becomes Noh.

In another embodiment, as shown in FIG. 7, the outputs of the mold opening displacement detector 41 and the injection displacement detector 42 are compared to achieve speed synchronization, and the setting value of the pressing force setting device 46 is adjusted. The synchronization is corrected by comparing the detected values of the injection pressure detector 45, and the maximum value of the pressing force on the biscuit 28 by the plunger tip 22 is limited, thereby preventing the biscuit 29 from breaking.
PJ - Nasuj Changai Honjima - [Effect of Departure 11] As described above, the present invention is to advance the plunger tip for pushing out the biscuit when opening the mold in synchronization with the withdrawal of the IIF movable mold. Since this is the mold opening III injection product ejection method in the injection molding machine, there is no need to press the biscuit when opening the mold.
Even if the inside of the biscuit is in an unsolidified state, the outer periphery of the biscuit will cool and solidify, and therefore, the mold can be opened only when the molten metal filling the cavity has sufficiently solidified. , the chill time in injection molding, and by extension the cycle time iT[, can be defined as τ'f fk, and the productivity of the product can be increased. The method controls the opening degree of the injection speed control valve by comparing the output of the mold opening displacement detector and the output of the injection displacement detector, and/or comparing the injection pressure with a pressing force setting value. Therefore, by using the injection speed control valve (flow control valve), injection cylinder position detection device, and injection pressure detector used to control the injection speed for product molding in conventional injection molding equipment, It can be easily implemented by simply adding a mold opening displacement detector, a pressing force 1 immersion device, a comparator, etc.

[Brief explanation of drawings]

Figure 1 is a diagram showing the main parts of injection molding device 4a, Figure 2 is a diagram with the movable mold slightly retracted, and Figure 3 is a diagram showing the mold 13Jf.
,! FIG. 4 is a diagram showing an example of an injection speed control valve, and FIGS. 5 to 7 are block diagrams showing examples of a control circuit. be. +1=mold, ]2=fixed mold, 13-movable mold. 15=cavity, 18=fixed platen, 17=movable platen, 18; link housing, 13=toggle mechanism, 20=mold clamping cylinder, 21=injection sleeve, 2
2==Plunger tip, 24=Injection plunger, 2
5=injection cylinder, 27=product, 29=biscuit,
41 = mold opening displacement detector, 42 = injection displacement detector, 4
3=differential amplifier, 44=injection speed controller, 45=injection pressure detector, 46=pushing force setting device, 48-flow control valve. 50=Injection speed control valve.

Claims (1)

[Claims] In injection molding, an injection cylinder that injects molten metal into a cavity and ejects a biscuit in a fixed mold when the mold is opened to take out the cast product after the required time for cooling the cast product in the mold has elapsed. When the mold is opened in an injection molding apparatus, the displacement of the movable mold is synchronized with the displacement of the movable mold when the mold is opened, so that the forward speed of the plunger tip and the backward speed of the movable mold are equalized. Injection product ejection method.