JPH0857927A - Injection press molding method and apparatus therefor - Google Patents

Abstract

PURPOSE: To reduce generation of defects such as torsion, distortion, wrinkles, cold mark, crack, underfill and the like in moldings by causing a fused resin in a cavity to be subjected to compression molding between dies or while stag gering the time, causing a fused resin in sub-chambers to be injected into the cavity through other gates to be united for compression molding. CONSTITUTION: A fused resin from an injection molding apparatus 20 is filled into sub-chambers 8a, 8b provided in a stationary die 3. The resin is injected from a first central gate 6a into a cavity 11 which is in an incompletely closed state, and during or after the injection a pressing force is acted to move a movable die 4. Then the fused resin in the cavity 11 is subjected to compression molding between the both dies 3, 4, and simultaneously or after some time the fused resin in the sub-chambers 8a, 8b is injected from a second gate 7 into the cavity 11 so that it is made unitary for compression molding. As a result, it is possible to decrease orientation in the resin to reduce residual strain, and to significantly reduce torsion, distortion and the like in moldings.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection press molding method and apparatus.

[0002]

2. Description of the Related Art In a conventional injection press molding method, a cavity having a long filling distance from a single gate may be used for injection press molding of a cup-shaped thin-walled deep-molded product. In this case, the pressing force effectively acts on the surfaces of the dies that define the cavity at a right angle to the closing direction of the two dies, so that it is possible to extend the resin. Vertical wall (circumferential surface)
Will be filled by the resin pressure acting on the right-angled surface. Therefore, when the filling distance from the single gate is long, insufficient filling or uneven filling pressure occurs on the vertical wall surfaces extending in the closing direction of both molds, which causes defective products.
In the vicinity of the tip of the cup-shaped thin deep metal mold, the resin is cooled and the flow becomes poor, causing cold marks, wrinkles, lack of wall and the like. For this reason, high-pressure injection is unavoidable, and burrs near the gate and twisting and distortion of the molded product due to uneven pressure distribution are likely to occur. In the injection press molding method, both molds are opened and injected into a cavity with a large volume in the injection process, but the vertical wall surface (circumferential surface) extending in the closing direction of both molds of the cavity is Unlike the surface located at right angles to the closing direction, the increase in volume is not so much obtained, and the thick space is not thickened, so that the flow resistance of the cavity cannot be sufficiently reduced.

Therefore, in the conventional injection press molding method, a multi-point gate is adopted to inject the resin from a plurality of locations of the cavity. When a multi-point gate is adopted, a method of simultaneously injecting from each gate or a method of individually controlling each gate is adopted. Since each of the multi-point gates and the injection device are connected only by the resin passage formed in the fixed mold, the injection amount of each gate is different from the flow resistance difference due to the length of the resin passage. Cause variations. It is conceivable to control the pressure, temperature, speed, or adjust the resin passage diameter for each gate so that this variation in the injection amount is reduced, but this also ensures the desired injection state in a stable manner. Difficult to do.

That is, in the conventional multi-point gate, it is difficult to control the flow rate resistance in order to keep the injection amount constant, and it is inevitable that the injection amount varies from gate to gate. As a result, the resin is oriented and residual strain remains in the molded product, so that the molded product is easily deformed such as twisted and distorted. This defect becomes remarkable when high-pressure injection is performed. In addition, high-pressure injection tends to cause burrs near the gate and has a large residual strain, which is a weak point in terms of physical properties.

A technical problem in such a conventional injection press molding method is that not only a cavity having a long flow distance locally with respect to a gate position but also a narrow or thin space in the whole or a part of the cavity is present. However, it is difficult to sufficiently fill the end portion by the injection pressing process while applying a relatively low pressure to prevent residual strain.

[0006]

The present invention has been made in view of the above conventional technical problems, and the structure thereof is as follows. The structure of the invention of claim 1 has a cavity 11 defined between the fixed mold 3 and the movable mold 4.
An injection press molding method for obtaining a molded product A ₀ by injecting a molten resin with both molds 3 and 4 in an incompletely closed state and applying a pressing force between the molds 3 and 4, Device 20
Sub-chambers 8a and 8'provided with molten resin from the fixed mold 3
A is injected into the cavity 11 in a not completely closed state from the first gate 6a in the central portion and a pressing force is applied to the movable mold 4 during or after the injection.
To move the molten resin in the cavity 11 to both molds 3,
It is characterized in that the molten resin in the sub-chambers 8a and 8'a is injected from the second gate 7a into the cavity 11 at the same time as or after a slight time lag when the compression molding is performed between the four sections, and the molten resin is integrated and compression molded. Is an injection press molding method.

According to the second aspect of the present invention, the molten resin is injected into the cavity 11 defined between the fixed mold 3 and the movable mold 4 while the molds 3 and 4 are not completely closed. In the injection press molding method, in which a pressing force is applied between the molds 3 and 4 to obtain a molded product A ₀ , the molten resin from the injection device 20 is supplied to the auxiliary chamber 8 a provided in the fixed mold 3. While filling, the cavity 11 in the incompletely closed state is injected from the first gate 6a in the central portion, and then the movable mold 4 is moved by applying a pressing force, and the melt is previously injected into the cavity 11. At the same time that the resin is compression-molded between the molds 3 and 4, the piston member 8b acted by the pressing force of the movable mold 4 is pushed into the sub-chamber 8a, and the molten resin in the sub-chamber 8a is cavities from the second gate 7a. It is injected into 11 and the molten resin is integrated to form compression. An injection press molding method, characterized by.

According to the third aspect of the present invention, the molten resin is injected into the cavity 11 defined between the fixed mold 3 and the movable mold 4 while the molds 3 and 4 are not completely closed. In the injection press molding method, in which a pressing force is applied between the two dies to obtain a molded product A ₀ , the molten resin from the injection device 20 is applied to an accumulator 8 ′ provided in the fixed mold 3. The cavity 11 that has been filled and injected into the cavity 11 which is not completely closed yet from the first gate 6a in the central portion, then moves the movable mold 4 by applying a pressing force, and is injected in advance from the first gate 6a. In the accumulator 8 ′, the molten resin in 11 is compression-molded between the molds 3 and 4, and the movable mold 4 moves at the same time or with a slight time difference, and operates independently of the movement of the movable mold 4. Second molten resin
This is an injection press molding method characterized by injecting from the gate 7a into the cavity 11.

According to a fourth aspect of the present invention, both dies 3 and 4 are not completely closed in the cavity 11 defined between the fixed die 3 and the movable die 4 which exerts a pressing force. An injection press molding apparatus for injecting a molten resin and applying a pressing force between the molds 3 and 4 to obtain a molded product A _{0, in} which the flow from the first gate 6 a formed in the central portion of the cavity 11 A sub-chamber 8a communicating with the cavity 11 is provided by a second gate 7a having a sub-chamber nozzle unit 7 having an opening / closing function so as to correspond to the vicinity of the cavity 11 having a large resistance, and slides in the sub-chamber 8a. The piston member 8b, which is freely fitted, is disposed so as to be able to contact the movable mold 4, and the injection device 20
The resin passage 10a interposing the switching valve 5 so that the molten resin from 1 is selectively filled in the sub chamber 8a and is selectively injected from the first gate 6a into the cavity 11 which is not completely closed. , 10b, 10c are provided, and the molten resin in the cavity 11 that has been pre-injected from the first gate 6a is compression-molded between the molds 3 and 4, and at the same time, the pressing force of the movable mold 4 acts on the piston member 8b. Sub chamber 8a
The molten resin in the sub-chamber 8a through the sub-chamber nozzle unit 7 and then from the second gate 7a to the cavity 11
It is an injection press molding apparatus characterized by injecting into.

According to a fifth aspect of the present invention, both dies 3 and 4 are not completely closed in the cavity 11 defined between the fixed die 3 and the movable die 4 which exerts a pressing force. An injection press molding apparatus for injecting a molten resin and applying a pressing force between the molds 3 and 4 to obtain a molded product A _{0, in} which the flow from the first gate 6 a formed in the central portion of the cavity 11 An accumulator 8 ′ communicating with the cavity 11 is provided by a second gate 7 a having a sub-chamber nozzle unit 7 having an opening / closing function so as to correspond to the vicinity of the cavity 11 having a large resistance, and melting from the injection device 20 is performed. The resin is selectively filled in the accumulator 8'provided in the fixed mold 3 and the cavity 1 which is not completely closed yet.
The resin passages 10a, 10b, 10c interposing the switching valve 5 so that the first gate 6a can be selectively injected.
The accumulator which is provided with the first gate 6a and is operated independently of the movement of the movable mold 4 at the same time as the molten resin in the cavity 11 pre-injected from the first gate 6a is compression-molded between the molds 3 and 4 or at the same time with a slight time lag. The injection press molding apparatus is characterized in that the molten resin in 8 ′ is injected into the cavity 11 from the second gate 7 a after passing through the sub chamber nozzle unit 7.

[0011]

According to the first aspect of the present invention, the molten resin from the injection device 20 is filled into the auxiliary chambers 8a and 8'a provided in the fixed mold 3 by a predetermined amount, and the cavity is in an incompletely closed state. 11 is ejected from the first gate 6a in the central portion by a predetermined amount. Since the molten resin is individually filled into the sub chambers 8a and 8'a and the cavity from the first gate 6a, the respective filling amounts can be accurately obtained. Further, the work of filling the sub-chamber 8a with the molten resin can be performed at a low pressure, and since the volume of the cavity 11 is expanded in the incompletely closed state, the entire amount of the volume can be supplied from the first gate 6a. In addition to the fact that there is no need to inject, the work of filling the molten resin from the first gate 6a can also be performed at low pressure.

During or after the injection from the first gate 6a, a pressing force is applied to move the movable mold 4, and the molten resin in the cavity 11 injected from the first gate 6a is transferred to both molds. Compression molding is performed between 3 and 4. The molten resin in the sub-chambers 8a and 8'a is injected into the cavity 11 from the second gate 7a at the same time as the compression molding of the molten resin in the cavity 11 or at some time later. As a result, a certain amount of the molten resin from the second gate 7a is accurately and directly directly filled in the vicinity of the cavity 11 where the flow resistance increases when the resin is injected from only the first gate 6a. Injected cavity 11
The molten resin inside is easily subjected to compression molding at low pressure, and these molten resins are integrated. In this way, both molds 3,
A molded product A ₀ having a predetermined shape is molded between 4 times.

The timing of injecting the molten resin in the sub chambers 8a and 8'a into the cavity 11 is as follows. That is, (1) the movable mold 4 is moved during the injection from the first gate 6a, and the molten resin in the sub-chambers 8a and 8'a is moved to the cavity 11 simultaneously with the compression molding of the molten resin in the cavity 11. When injecting, (2) first gate 6
The movable mold 4 is moved in the middle of injection from a, and the molten resin in the sub-chambers 8a and 8'a is moved to the cavity 11 by slightly shifting the compression molding of the molten resin in the cavity 11 back and forth.
(3) the movable mold 4 is moved after the injection from the first gate 6a is completed, and the molten resin in the sub-chambers 8a and 8'a is simultaneously compressed and molded in the cavity 11. When injecting into the cavity 11, (4) move the movable mold 4 after the injection from the first gate 6a is completed,
This is a case in which the molten resin in the sub-chambers 8a and 8'a is injected into the cavity 11 by slightly shifting the compression molding of the molten resin in the cavity 11 back and forth.

According to the second aspect of the present invention, the molten resin from the injection device 20 is filled in the auxiliary chamber 8a provided in the fixed mold 3 by a predetermined amount and the cavity 11 in the incompletely closed state is centered. A predetermined amount is ejected from the first gate 6a of the part. Inside the sub chamber 8a and from the first gate 6a to the cavity 1
Since the molten resin is individually filled in 1, the filling amount of each can be accurately obtained. Furthermore, the work of filling the molten resin into the sub chamber 8a can be performed at a low pressure, and
In the incompletely closed state, the volume of the cavity 11 is expanded, so that it is not necessary to inject the entire volume of the cavity from the first gate 6a.
The work of filling from the gate 6a can also be performed at low pressure.

Thereafter, a pressing force is applied to move the movable die 4
Is moved and the piston member 8b to which the pressing force of the movable mold 4 is applied is pushed into the sub chamber 8a, the molten resin in the sub chamber 8a is injected from the second gate 7a into the cavity 11 and at the same time The molten resin in the cavity 11 injected from the gate 6a in advance is compression-molded between the molds 3 and 4. As a result, in the vicinity of the location of the cavity 11 where the flow resistance increases when injected only from the first gate 6a,
A certain amount of the molten resin from the second gate 7a is directly directly filled, and the molten resin in the cavity 11 pre-injected from the first gate 6a is easily subjected to compression molding at a low pressure. Are integrated. In this way, a molded product A ₀ having a predetermined shape is molded between the molds 3 and 4.

According to the third aspect of the present invention, the molten resin from the injection device 20 is filled in the accumulator 8'provided in the fixed mold 3 by a predetermined amount, and the cavity 11 in the incompletely closed state is centrally filled. A predetermined amount is ejected from the first gate 6a. Inside the accumulator 8'and the first gate 6
Since the molten resin is individually supplied into the cavity 11 from a, the respective supply amounts can be accurately obtained.
Furthermore, the work of filling the molten resin into the accumulator 8 ′ can be performed at a low pressure, and since the volume of the cavity 11 is expanded in the incompletely closed state, the entire amount of the volume is discharged from the first gate 6a. In addition to the fact that there is no need to inject, the work of filling the molten resin from the first gate 6a can also be performed at low pressure.

Thereafter, a pressing force is applied to the movable mold 4
Is moved, the molten resin in the cavity 11 that is previously injected from the first gate 6a is compression-molded between the molds 3 and 4. In addition, the accumulator 8 ′ is operated independently of the movement of the movable mold 4 at the same time as or slightly before and after the movement of the movable mold 4 to move the molten resin in the accumulator 8 ′ from the second gate 7a to the cavity 11a. Inject. As a result, a certain amount of the molten resin from the second gate 7a is accurately and directly directly filled in the vicinity of the cavity 11 where the flow resistance increases when the resin is injected from only the first gate 6a. The molten resin in the cavity 11 injected in advance is also easily subjected to compression molding at low pressure, and these molten resins are integrated. In this way,
A molded product A ₀ having a predetermined shape is molded between the molds 3 and 4.

According to the fourth aspect of the present invention, the molten resin from the injection device 20 is filled through the resin passages 10a and 10b into the auxiliary chamber 8a provided in the fixed mold 3 in a predetermined amount, and the resin passages 10a and 10a A predetermined amount is injected from the first gate 6a at the center into the cavity 11 which is not completely closed through 10c. At this time, the sub chamber nozzle unit 7 is closed and the switching valve 5 is switched. Since the molten resin is individually supplied into the sub chamber 8a and into the cavity 11 from the first gate 6a, the respective supply amounts can be accurately obtained. Further, the operation of filling the sub-chamber 8a with the molten resin can be performed at a low pressure, and since the volume of the cavity 11 is expanded in the incompletely closed state, the entire amount of the volume from the first gate 6a is increased. In addition to the fact that it is not necessary to inject, the work of filling the molten resin from the first gate 6a can also be performed at a low pressure.

Thereafter, a pressing force is applied to move the movable die 4
Is moved and the piston member 8b to which the pressing force is applied by the movable mold 4 is pushed into the sub chamber 8a, the molten resin in the sub chamber 8a passes through the opened sub chamber nozzle unit 7 to the second gate. 7a is injected into the cavity 11, and at the same time, the cavity 11 is previously injected from the first gate 6a.
The molten resin inside is compression-molded between the molds 3 and 4. The reverse flow of the molten resin from the sub chamber 8a and the cavity 11 can be prevented by switching the switching valve 5. As a result, in the vicinity of the location of the cavity 11 where the flow resistance increases when injected only from the first gate 6a,
A certain amount of the molten resin from the second gate 7a is directly and directly filled, and at the same time, the molten resin in the cavity 11 pre-injected from the first gate 6a easily undergoes compression molding at a low pressure to melt them. Resin is integrated. In this way, a molded product A ₀ having a predetermined shape is molded between the molds 3 and 4.

According to the fifth aspect of the present invention, the molten resin from the injection device 20 is filled into the accumulator 8'provided in the fixed mold 3 through the resin passages 10a and 10b by a predetermined amount, and the resin passages 10a and 10a, 10c through the first gate 6 in the central portion to the cavity 11 which is not completely closed.
Fill a predetermined amount from a. At this time, the sub chamber nozzle unit 7 is closed and the switching valve 5 is switched. Since the molten resin is individually filled into the accumulator 8 ′ and the cavity 11 from the first gate 6a, the respective filling amounts can be accurately obtained. Furthermore, the operation of filling the molten resin into the accumulator 8 ′ can be performed at a low pressure, and since the volume of the cavity 11 is expanded in the incompletely closed state,
In addition to the fact that it is not necessary to inject the entire volume from the first gate 6a, the work of filling the molten resin from the first gate 6a can be performed at low pressure.

Thereafter, a pressing force is applied to the movable mold 4
Is moved, the molten resin in the cavity 11 that is previously injected from the first gate 6a is compression-molded between the molds 3 and 4. In addition, the accumulator 8 ′ is operated independently of the movement of the movable mold 4 at the same time as the movement of the movable mold 4 or with a slight time shift, so that the molten resin in the accumulator 8 ′ is
It is injected from the second gate 7a into the cavity 11 through the opened sub chamber nozzle unit 7. Thereby, the first
A certain amount of the molten resin from the second gate 7a is accurately and directly filled in the vicinity of the cavity 11 where the flow resistance increases when injected from only the gate 6a, and the cavity injected in advance from the first gate 6a. The molten resin in 11 is also easily subjected to compression molding at low pressure, and these molten resins are integrated. In this way, a molded product A ₀ having a predetermined shape is molded between the molds 3 and 4.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an injection press molding apparatus according to a first embodiment of the present invention. In the figure, reference numeral 1 indicates a fixed platen, and a fixed mold 3 is fixed on the horizontally arranged fixed platen 1. The fixed mold 3 is provided with a cavity surface 11a having an open upper end, a first gate 6a opening at the center bottom of the cavity surface 11a, and a vertical surface of the cavity surface 11a (closing direction of both molds 3 and 4). An appropriate number of second gates 7a are formed in the middle of the vertical wall surface extending in the vertical direction.

Further, the injection device 2 is provided on the side surface of the fixed mold 3.
The sprue 10d with which the No. 0 nozzle closely contacts is formed, and the main resin passage 10a connected to this sprue 10d has the first resin passage 10c and the second resin passage 1 through the switching valve 5.
0b can be selectively connected. First resin passage 10c
Is connected to the first gate 6a via the nozzle unit 6, and the second resin passages 10b are individually connected to the second gate 7a via the cylindrical sub chamber 8a and the sub chamber nozzle unit 7. ing. The nozzle unit 6 and the sub chamber nozzle unit 7 have an opening / closing function and have the same structure as a shutoff nozzle, a needle nozzle, or the like.

The main resin passage 10a and the first resin passage 10
A heater (not shown) is attached to each of the c and the second resin passages 10b to serve as a hot runner. Second
The gate 7a can be formed in a single or plural number corresponding to the vicinity of the cavity 11 where the flow resistance from the first gate 6a is large, and the molten resin is filled in every corner of the cavity 11 where injection pressure and pressing force are difficult to apply. It has the function of 20 a is a screw of the injection device 20. The cavity surface 11a of the fixed mold 3 is insulated from the heater of the resin passages 10a, 10b, 10c (hot runner) by the heat insulating material 12.

On the other hand, a movable platen 2 which is vertically movable is arranged above the fixed mold 3. A movable mold 4 is fixed to the movable plate 2 so as to face the fixed mold 3. The movable mold 4 is formed with a cavity surface 4a, and a spacer 8c having a predetermined thickness is fixed to the peripheral portion. The spacer 8c corresponds to the piston member 8b slidably fitted in each sub-chamber 8a in the vertical direction (the closing direction of the two dies 3 and 4).
The piston member 8b constitutes an accumulator 8 which is activated by the movement of the movable mold 4. The cavity surface 4 a of the movable mold 4 is the cavity surface 1 of the fixed mold 3.
A cavity 11 is defined between the cavity 11 and 1a. This sub-chamber 8a
Is attached with a heating device (not shown) including a heater. A mold position detector 9 for detecting the vertical position of the movable mold 4 is provided between the fixed mold 3 and the movable mold 4. This movable mold 4 is actuated by a pressing force F by a press device (not shown) to descend to close the mold, and
The mold opening can be performed by applying an attractive force opposite to the applied pressure F.

Next, the operation of the above embodiment will be described. First, during the mold opening process of the movable mold 4 or in the mold opened state in which the movable mold 4 is sufficiently raised, the molten resin from the injection device 20 is passed through the sprue 10d, the main resin passage 10a, and the second resin passage 10b. A predetermined amount is injected into the chamber 8a. At this time, the switching valve 5 is switched to the same position as shown in FIG. 2 to move the main resin passage 10a to the respective second resin passages 10b.
And the auxiliary chamber nozzle unit 7
Therefore, the second gate 7a is closed. This sub-chamber 8
The molten resin can be supplied to a by injection at a very low pressure. The fact that the molten resin from the injection device 20 has been injected into each sub chamber 8a by a predetermined amount can be known by detecting that the screw 20a of the injection device 20 has advanced by a predetermined length. Therefore, each sub-chamber 8a can be accurately filled with a certain amount of molten resin.

Next, the movable mold 4 is appropriately lowered, and both molds 3 and 4 are brought into an incompletely closed state as shown in FIG.
It is assumed that the cavity 11 that is slightly larger than the predetermined size in the mold closed state is partitioned. The fact that the movable mold 4 has reached a predetermined incompletely closed state can be detected and detected by the mold position detector 9. In this state, the molten resin from the injection device 20 is passed through the sprue 10d and the main resin passage 1
0a, the first resin passage 10c and the first gate 6a are injected into the cavity 11. At this time, the switching valve 5 is switched as shown in FIG. 1 to connect the main resin passage 10a to the first resin passage 10c, the nozzle unit 6 is opened, and the first gate 6 is passed through the nozzle unit 6.
A predetermined amount of molten resin A is injected into the cavity 11 from a. The injection of the molten resin A from the first gate 6a, which is performed in a state where both the molds 3 and 4 are not completely closed, is performed as follows.
Since the injection is performed into the cavity 11 having a thick space of "α", the flow resistance in the cavity 11 causes almost no problem and a certain amount of injection can be performed at a very low pressure.

A pressing force F is applied to the movable mold 4 to move the movable mold 4 downward again in the mold closing direction, and at the same time, the pressing force by the movable platen 2 and the movable mold 4 is incorporated into the fixed mold 3. The piston member 8b, and the piston member 8b
Is lowered to compress the inside of the sub chamber 8a. Thereby, the first
The molten resin A injected from the gate 6a into the cavity 11 is compressed by the molds 3 and 4, and at the same time, the sub chamber 8
The molten resin in a is extruded and is ejected from the second gate 7a. At that time, the switching valve 5 remains in the switching position shown in FIG. 1 to block the second resin passages 10b and the nozzle unit 6 to block the first gate 6a so that the molten resin A in the cavity 11 becomes It is prevented from flowing out from one gate 6a. If the switching valve 5 is provided with a position that blocks both the first resin passage 10c and each second resin passage 10b, it is not necessary to shut off the first gate 6a by the nozzle unit 6.

By applying a pressing force F, both molds 3,
The timing of starting the compression molding of the molten resin in the cavity 11 between 4 may be not only after the injection from the first gate 6a in the central portion into the cavity 11 but also during the injection. Even during this injection, a certain amount of the molten resin A can be injected at a relatively low pressure immediately after the start of compression molding. Thereby, the molding cycle can be shortened.

In the auxiliary chamber 8a, a certain amount of the molten resin A injected into the cavity 11 through the first gate 6a is spread by the molding press force into the cavity 11. A certain amount of molten resin is injected. The position of the second gate 7a is set to a plurality of locations (or a single location) by selecting a location where the injection pressure from the first gate 6a is difficult to reach.
The molten resin inside is appropriately supplied to these places, and the molten resin is well filled up to the end of the cavity 11. The injection from the sub chamber 8a is performed by the piston member 8b.
Is fully lowered, that is, the mold clamping of both molds 3 and 4 is completed, and the process ends. Of course, the total amount of the molten resin supplied from the first gate 6a and the second gate 7a into the cavity 11 is set to be equal to the volume of the molded product A ₀ . It should be noted that the thickness of the spacer 8c can be increased or decreased to properly maintain the amount of depression of the piston member 8b.

The injection if press molding is finished molded article A ₀ has cooled, the mold is opened by the movable mold 4 is moved upward as shown in FIG. 3, an unillustrated by connexion molded article ejector pin A ₀
Stick out. The replenishment of the molten resin from the injection device 20 to the sub chamber 8a is started by switching the switching valve 5 after the movable mold 4 is moved upward, and is completed before the next injection from the first gate 6a. By supplying the molten resin to the sub chamber 8a, the piston member 8b rises. Molded product A ₀ in cavity 11
During cooling, the kneading process is performed by the injection device 20.

By the way, the molten resin A injected from the first gate 6a into the cavity 11 and the molten resin injected from the sub chamber 8a into the cavity 11 are formed of a sintered plate or the like having a communication hole at a confluence. It is possible to form a gas vent and prevent insufficient filling due to the presence of air at this confluence. Further, the present invention can be applied not only to the vertical injection press molding apparatus as shown but also to the horizontal injection press molding apparatus.

FIG. 4 shows an injection press molding apparatus according to the second embodiment of the present invention. The parts substantially the same as those in the first embodiment are designated by the same reference numerals and their description is omitted. In this embodiment, the piston member 8'b is fitted in the auxiliary chamber 8'a formed in the fixed mold 3 so as to be slidable in the left-right direction while avoiding interference with the movable mold 4. .

The injection of the molten resin in the sub chamber 8'a is not the molding press force associated with the downward movement of the movable mold 4,
It is performed in a timely manner by a pressurizing device 18 such as a hydraulic cylinder device which is separately provided. As a result, the same operation as that of the first embodiment can be obtained, and the injection timing from the sub chamber 8'a can be arbitrarily set irrespective of the downward movement of the movable mold 4 to expand the application range of the work. . The injection timing of the molten resin from the sub chamber 8'a is actually set at the same time as the press compression molding or before and after the press compression molding with a slight time lag. The sub-chamber 8'a, the piston member 8'b and the pressurizing device 18 constitute an accumulator 8'that operates independently of the downward movement of the movable mold 4.

[0035]

As can be understood from the above description,
According to the injection press molding method and the apparatus therefor of the present invention, the following effects can be achieved. In the injection press molding method and apparatus having a cavity having a shape having a portion having a long flow distance or a local portion with respect to the position of the first gate, the second gate is arranged at that portion. This allows
Even in a region having a long flow distance with respect to the first gate position and poor fluidity, it is possible to inject a constant amount in a well-balanced and reliable manner by low-pressure injection. As a result, the orientation of the resin is reduced, the residual strain is reduced, and the molded product is twisted, distorted, wrinkled, cold marks, cracks,
The occurrence of defects such as lack of meat is significantly reduced.

Even if the cavity has a shape such that the thickness space does not become too thick even if both molds are opened in the injection pressing step, by arranging the second gate corresponding to the thin portion, the inside of the cavity In addition, the molten resin is injected at a low pressure to prevent insufficient filling and uneven filling pressure. In addition, the injection amount at each of the plurality of gates can be made constant at each injection, and it is possible to prevent variations in the injection amount at each gate. Therefore, it is possible to stably secure a desired injection state and obtain a high-quality molded product. As a result, the maximum injection pressure of the injection device and the pressing force applied to the movable mold are small, and the equipment cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an injection press molding apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory view of the same operation.

FIG. 3 is an explanatory view of the same operation.

FIG. 4 is a sectional view showing a fixed mold of an injection press molding apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

3: Fixed mold, 4: Movable mold, 5: Switching valve, 6: Nozzle unit, 6a: First gate, 7: Sub chamber nozzle unit, 7a: Second gate, 8, 8 ': Accumulator, 8a , 8'a: sub chamber, 8b, 8'b: piston member, 10a: main resin passage (resin passage), 10b: second resin passage (resin passage), 10c: first resin passage (resin passage), 10d : Sprue, 11: cavity, 18: pressurizing device, 20: injection device, A ₀ : molded product.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiharu Karaushi 4th Chazu-cho, Muroran-shi, Hokkaido Inside Nikko Tokki Co., Ltd. 72) Inventor Yukio Sato 4 Chazu-cho, Muroran-shi, Hokkaido Nikko Tokki Co., Ltd.

Claims (5)

[Claims] 1. A mold (3) is provided in a cavity (11) defined between a fixed mold (3) and a movable mold (4).
An injection press molding method in which a molten resin is injected in a state where the mold is not completely closed, and a pressing force is applied between the molds (3, 4) to obtain a molded product (A ₀ ). The molten resin from the sub-chamber (8a,
8'a) is filled, and is injected from the first gate (6a) in the central portion into the cavity (11) that is not completely closed, and is moved by applying a pressing force during or after the injection. When the mold (4) is moved and the molten resin in the cavity (11) is compression-molded between the molds (3, 4) at the same time or with a slight time lag, the sub-chambers (8a, 8'a) An injection press molding method comprising injecting a molten resin from the second gate (7a) into the cavity (11) to integrate the molten resin and perform compression molding. 2. A die (3, 4) in a cavity (11) defined between a fixed die (3) and a movable die (4).
An injection press molding method in which a molten resin is injected in a state where the mold is not completely closed, and a pressing force is applied between the molds (3, 4) to obtain a molded product (A ₀ ). Sub-chamber (8a) provided with molten resin from fixed mold (3)
And the cavity (11) in the incompletely closed state is injected from the first gate (6a) in the central portion, and then the movable die (4) is moved by applying a pressing force to move the cavity (11). ) A piston member (8b) in which a molten resin that has been previously injected into the mold is compression molded between both molds (3, 4), and at the same time a pressing force is applied by the movable mold (4).
Is injected into the sub-chamber (8a) to inject the molten resin in the sub-chamber (8a) from the second gate (7a) into the cavity (11), and the molten resin is integrated and compression-molded. Press molding method. 3. A cavity (11) defined between a fixed die (3) and a movable die (4), wherein both dies (3, 4) are provided.
An injection press molding method in which a molten resin is injected in a state where the mold is not completely closed, and a press force is applied between the molds (3, 4) to obtain a molded product (A ₀ ). The molten resin from (1) was filled in the accumulator (8 ') provided in the fixed mold (3), and was injected from the first gate (6a) in the central portion into the cavity (11) that was not completely closed, and then , The movable mold (4) is moved by applying a pressing force, and the molten resin in the cavity (11) injected in advance from the first gate (6a) is compression-molded between the molds (3, 4). At the same time, the molten resin in the accumulator (8 ') which operates independently of the movement of the movable mold (4) is moved from the second gate (7a) at the same time as the movement of the movable mold (4) or with some time lag. An injection pre, characterized by injecting into a cavity (11) Molding method. 4. A cavity (11) defined between a fixed mold (3) and a movable mold (4) for exerting a pressing force.
Injection molding in which both molds (3, 4) are not completely closed and a molten resin is injected, and a pressing force is applied between the molds (3, 4) to obtain a molded product (A ₀ ). A device
The first gate (6) formed in the center of the cavity (11)
It is connected to the cavity (11) by a second gate (7a) having a sub-chamber nozzle unit (7) having an opening / closing function, corresponding to the vicinity of the cavity (11) having a large flow resistance from a). A sub-chamber (8a) for
A piston member (8b) slidably fitted in a) is arranged so as to be able to contact the movable mold (4), and molten resin from the injection device (20) selectively enters the sub chamber (8a). Resin passages (10a, 10b, 10) interposing a switching valve (5) so that the first gate (6a) is selectively injected into the cavity (11) that is filled and is not completely closed.
c) is provided, and the molten resin in the cavity (11) injected in advance from the first gate (6a) is compression-molded between the molds (3, 4), and at the same time, the pressing force of the movable mold (4) is applied. After pushing the actuated piston member (8b) into the sub-chamber (8a) and passing the molten resin in the sub-chamber (8a) through the sub-chamber nozzle unit (7), the second gate (7a) to the cavity (11) An injection press molding device characterized by injecting into. 5. A cavity (11) defined between a fixed mold (3) and a movable mold (4) for exerting a pressing force.
Injection molding in which the molds (3, 4) are not completely closed and the molten resin is injected, and a pressing force is applied between the molds (3, 4) to obtain a molded product (A ₀ ). A device
The first gate (6) formed in the center of the cavity (11)
It is connected to the cavity (11) by a second gate (7a) having a sub-chamber nozzle unit (7) having an opening / closing function, corresponding to the vicinity of the cavity (11) having a large flow resistance from a). A cavity which is provided with an accumulator (8 ') for selectively filling the accumulator (8') provided in the fixed mold (3) with the molten resin from the injection device (20) and is not completely closed yet. (1
The resin passages (10a, 1) interposing the switching valve (5) so as to be selectively injected from the first gate (6a) to (1).
0b, 10c) and the molten resin in the cavity (11) pre-injected from the first gate (6a) is compressed between the two dies (3, 4) at the same time or with a slight time lag, so that the movable metal The molten resin in the accumulator (8 ') that operates independently of the movement of the mold (4) is injected from the second gate (7a) into the cavity (11) after passing through the sub chamber nozzle unit (7). Injection press molding equipment.