JP2865982B2 - Local pressure type injection molding method and local pressure type injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a local pressurized injection molding method and a local pressurized injection molding machine.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a screw is disposed in a heating cylinder so as to be rotatable and advanceable and retractable. In a measuring step, the screw is rotated and retracted to melt a resin in front of the screw. In the storing and filling (10) step, the screw is advanced to inject the molten resin from the injection nozzle and fill the cavity of the mold.

On the other hand, the mold comprises a fixed mold and a movable mold, and the movable mold can be moved forward and backward by a mold opening / closing device so as to be brought into and out of contact with the fixed mold. Therefore, the movable mold is brought into contact with the fixed mold to close the mold, the movable mold is pressed against the fixed mold, the mold is clamped, then the cavity is filled with resin, and the resin is cooled and molded. Goods. The molded product can be pushed down by moving the movable mold away from the fixed mold to open the mold, and ejecting the ejector pins from the fixed mold.

The resin injected from the injection nozzle enters a runner through a sprue, and is filled from the runner through the gate into the cavity. For example, when the gate is of a submarine type, a portion corresponding to the gate (hereinafter, referred to as a “gate portion”) is automatically folded when the molded product is pushed down, and is separated from the molded product. I have.

[0005] However, after the gate portion is separated, a gate mark remains or flash occurs on the molded product. Therefore, an operation for removing gate marks and burrs is required, which increases costs. Therefore, there has been provided a local pressurized injection molding machine in which a pressurizing pin is provided corresponding to the gate portion, and the pressurizing pin is advanced to cut the gate. In this case, no gate mark remains or burrs occur.

[0006]

However, in the above-mentioned conventional local pressurized injection molding machine, if the molded product is large or thick, if the molded product has a flow end portion or a thick portion in the cavity. Insufficient resin in the flesh portion causes sink marks, and unbalance of linear shrinkage causes inner sled.

[0007] The present invention solves the problems of the above-mentioned conventional local pressurized injection molding machine, and causes sink marks at a flow end portion or a thick portion in a cavity, and internal sled due to unbalance of linear shrinkage. It is an object of the present invention to provide a local pressurization type injection molding method and a local pressurization type injection molding machine which can prevent the occurrence of cracks.

[0008]

For this purpose, in the local pressurized injection molding method of the present invention, the first local pressurized pin is advanced to push the resin in front of the first local pressurized pin into the cavity. The timing at which the second local pressure pin is advanced to push the resin in front of the second local pressure pin into the cavity, and the first local pressure pin is started to advance and the second local pressure pin is advanced At different times.

Further, in the local pressurized injection molding machine of the present invention, a fixed mold, a movable mold which is disposed so as to be able to contact and separate from the fixed mold and forms a cavity between the two, and a movable mold. The first, which extends through the mold, with the tip facing the cavity
It has a local pressure pin and a second local pressure pin extending through the movable mold and having a tip facing the cavity. Also, a pressure plate is provided for supporting rear ends of the first local pressure pin and the second local pressure pin. The pressure plate has a play formed on a rear end of at least one of the first local pressure pin and the second local pressure pin, and
The effective stroke of the local pressure pin is made different from the effective stroke of the second local pressure pin.

[0010]

According to the present invention, as described above, in the local pressure type injection molding method, the first local pressure pin is advanced to push the resin in front of the first local pressure pin into the cavity, and the second local pressure pin is pushed into the cavity. The local pressure pin is advanced to push the resin in front of the second local pressure pin into the cavity, and the timing of starting the advance of the first local pressure pin and starting the advance of the second local pressure pin The timing to make them differ.

Accordingly, the resin injected from the injection nozzle is filled into the cavity through the gate, and at this time, the resin is also filled in front of the first local pressure pin and the second local pressure pin. Then, one of the first local pressure pin and the second local pressure pin advances, and thereafter, the other of the first local pressure pin and the second local pressure pin starts to advance. At this time, the other of the first local pressure pin and the second local pressure pin pushes the front resin into the cavity.

Further, in the local pressurized injection molding machine of the present invention, a fixed mold, a movable mold which is disposed so as to be able to contact and separate from the fixed mold and forms a cavity therebetween, and a movable mold The first, which extends through the mold, with the tip facing the cavity
It has a local pressure pin and a second local pressure pin extending through the movable mold and having a tip facing the cavity. Also, a pressure plate is provided for supporting rear ends of the first local pressure pin and the second local pressure pin. The pressure plate has a play formed on a rear end of at least one of the first local pressure pin and the second local pressure pin, and
The effective stroke of the local pressure pin is made different from the effective stroke of the second local pressure pin.

Therefore, the resin injected from the injection nozzle is filled into the cavity through the gate, and at this time, the resin is also filled in front of the first local pressure pin and the second local pressure pin. Then, when the pressing plate starts to advance, one of the first local pressing pin and the second local pressing pin advances, and when the pressing plate advances by an amount corresponding to the play, the first local pressing pin moves. The other of the pin and the second local pressure pin starts moving forward. At this time, the other of the first local pressure pin and the second local pressure pin pushes the front resin into the cavity.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a local pressurized injection molding machine showing a first embodiment of the present invention, FIG. 2 is a state diagram of the local pressurized injection molding machine according to the first embodiment of the present invention before local pressurization, FIG. 3 is a state diagram after the local pressurization of the local pressurized injection molding machine according to the first embodiment of the present invention. 2A and 3A are cross-sectional views of the vicinity of the cavity, and FIGS. 2B and 3B are diagrams of the mold internal pressure characteristics at each position of the resin flow path. Note that FIG.
In FIGS. 3 and 3 (b), the vertical axis indicates the in-mold pressure, and the horizontal axis indicates the position.

In the drawing, reference numeral 11 denotes a fixed mold mounting plate;
Denotes a fixed die, and the fixed die 12 is mounted on a fixed platen (not shown) via the fixed die mounting plate 11. Then, the injection device (not shown) advances in the injection process, and the tip of the injection nozzle (not shown) is brought into contact with the sprue bush 13 of the fixed mold 12. On the other hand, a movable platen (not shown) is advanced and retracted by a mold opening / closing device (not shown) so that the movable mold 14 is brought into and away from the fixed mold 12. Therefore, the movable mold 14 is fixed to a movable platen via a movable mold mounting plate 15 and a spacer block (not shown).

The resin injected from the injection nozzle enters the runner 19 through the sprue 18, passes through the submarine type gate 20 from the runner 19, and enters the fixed mold 1.
The cavity 21 formed between the mold 2 and the movable mold 14 is filled. When the injection process is completed, the process enters a pressure-holding process, in which the mold internal pressure in the cavity 21 is maintained and the resin starts to be cooled.
4 and the two molds 12 and 1 are kept in a state where a molded product (not shown) is left.
4 is opened and the molded product is pushed down by the ejector device.

For this purpose, a sprue lock pin 25 and an ejector pin 26 are provided. The sprue lock pin 25 is disposed facing the sprue 18 and holds the molded product when the mold is opened, and leaves it on the movable mold 14 side. The ejector pins 26 are disposed so as to face the cavity 21 and the runner 19, and protrude from the movable mold 14 after the mold is opened, and separate the molded product from the movable mold 14 and push it down.

Head portions 25a, 26 formed at the rear ends of the sprue lock pin 25 and the ejector pin 26
a is sandwiched and fixed by the ejector plates 31 and 32. The ejector plates 31 and 32 are supported so as to be able to move forward and backward, and advance the sprue lock pin 25 and the ejector pin 26 as they move forward. As shown in FIG. 1, a gap (gap) is formed between the ejector plate 32 and the rear end of the movable mold 14 at the retreat limit of the ejector pin 26. The gap becomes a stroke of the ejector pin 26.

An ejector rod contact member 33 is fixed to the rear end of the ejector plate 32, and an ejector rod of an ejector cylinder (not shown) contacts the ejector rod contact member 33.
Accordingly, the ejector plates 31 and 32 can be advanced and retracted by operating the ejector cylinder.

Incidentally, the resin filled in the cavity 21 contracts with cooling, and the specific volume decreases. Therefore, a first local pressure pin 34 is provided in order to cut the gate and process the molded product to improve the quality. The first local pressure pin 34 extends forward through the ejector plates 31, 32 and the movable mold 14, and its tip faces the cavity 21 via the gate 20.
At the time of forward movement, the gate is cut, and the resin filled in the disposal boss 21 a in front of the first local pressure pin 34 is pushed into the cavity 21.

However, when the molded product is large and has a long flow length, the flow ends in the cavity 21 are insufficient in resin, causing sink marks. That is, as shown in FIG. 2A, the connection between the sprue 18 and the runner 19 is point a, the end of the runner 19 is point b, the gate is point c, and the flow end in the cavity 21 is Is the point d, as shown in FIG. 2B, at the point d, the resin is insufficient and the mold inner pressure is reduced. Therefore, sink marks occur at the point d.

Therefore, a second local pressure pin 35 is provided. The second local pressure pin 35 extends forward through the ejector plates 31 and 32 and the movable mold 14, and has a tip of the cavity 21. Face the end of flow. After the inside of the cavity 21 is cut off from the runner 19 by the first local pressure pin 34 and the filling of the resin is cut off, the resin of the discard boss portion 21b in front of the second local pressure pin 35 when moving forward. Can be pushed into the cavity 21. The second local pressure pin 35
Are provided in large numbers in the cavity 21 where the mold pressure is reduced.

The first and second local pressure pins 34 and 35
Are set to have different effective strokes L _D and L _C from each other. The first and second local pressure pins 34,
In addition to 35, other local pressure pins with further different effective strokes can be provided. Since the head portion 34a formed at the rear end of the first local pressure pin 34 is sandwiched and fixed by the pressure plates 36 and 37, the effective stroke L _D of the first local pressure pin 34 is increased. the same value as the movement stroke L _a of the plate 36, 37.

The stepped portion 35 a formed at the rear end of the second local pressure pin 35 is provided with pressure plates 36 and 37.
It is housed in the stepped portion housing chamber 38 formed between them, and
It is arranged movably. A rear pin portion 35b is formed behind the stepped portion 35a to protrude through the pressure plate 37. Here, the stepped portion accommodation room 3
The depth of 8 value greater than the thickness of the stepped portion 35a, play L _B is formed.

Therefore, the effective stroke L _C of the second local pressure pin 35 is L _C = L _D -L _B = L _A -L _B. Thus, the effective stroke L _{D of} the first local pressure pin 34 and the effective stroke L _D of the second local pressure pin 35
_C can be different. Further, the timing for starting the advance of the first local pressure pin 34 and the timing for starting the advance of the second local pressure pin 35 can be made different. If a different effective stroke is required, the pressure plate 3 is attached to the rear end of another local pressure pin.
6 and 37 form a different value of play.

A pressure rod contact member 39 is fixed to the rear end of the pressure plate 37, and a pressure rod of a pressure cylinder (not shown) comes into contact with the pressure rod contact member 39. I have. Therefore, the pressure plates 36 and 37 can be moved forward and backward by operating the pressure cylinder. Reference numeral 41 denotes a pressure plate guide pin for guiding the pressure plates 36 and 37. The tip of the pressure plate guide pin 41 is connected to the ejector plate 31,
The effective stroke L _D is set by penetrating through the mold 32 and the movable mold 14 and facing the fixed mold 12.

Next, the first and second local pressure pins 34,
The operation of 35 will be described. The resin injected from the injection nozzle enters the runner 19 through the sprue 18, passes through the submarine type gate 20 from the runner 19, and enters the cavity 21 formed between the fixed mold 12 and the movable mold 14. Is filled. At this time, the discarded boss 21
Resins are also filled in a and 21b.

Then, after the filling of the resin into the cavity 21 is completed, at a set time from 0.5 seconds to several seconds, the pressurizing cylinder is operated, the pressurizing rod is advanced, and the pressurizing is performed. It is brought into contact with the pressure rod contact member 39.
At this time, the pressure plates 36 and 37 start moving forward. When the pressure plates 36 and 37 start moving forward,
Since the first local pressure pin 34 also starts moving forward and cuts the gate, the inside of the cavity 21 is cut off from the runner 19.
At this time, the resin in the cavity 21 contracts with cooling and the specific volume decreases.

Therefore, the first local pressure pin 34 continues to move forward even after the filling of the resin is cut off, and the resin of the waste boss 21a is pushed into the cavity 21 even after the filling of the resin is cut off. The effective stroke L _D is set so as to perform the following. By the way, when the pressure plates 36 and 37 are at the initial position where they come into contact with the movable mold mounting plate 15, the rear pin portions 35b of the second local pressure pins 35
Is moved forward by being pressed by the movable mold mounting plate 15, and the stepped portion 35 a is also at the front position in the stepped portion accommodation chamber 38. When the pressurizing cylinder operates and the pressurizing plates 36 and 37 move forward away from the movable mold mounting plate 15, the second local pressurizing pin 35 becomes a stepped portion 35.
a is maintained in the stopped state until the back by L _B content play a stepped portion accommodating chamber 38.

[0030] Therefore, the stepped portion 35a with the forward movement of the pressure plate 36, 37 is retracted by L _B content play a stepped portion accommodating chamber 38, the second local pressurizing pin 35 begins to move forward. Then, as shown in FIG.
Since the resin of the discard boss 21b is pushed into the cavity 21 with the advance of the local pressure pin 35, the internal pressure of the mold in the cavity 21 can be made uniform as shown in FIG. It is possible to prevent sink marks from occurring at the distal end.

Then, the second local pressure pin 35 pushes the resin of the waste boss 21b into the cavity 21, and the pressure plates 36 and 37 advance by the effective stroke L _{D of} the first local pressure pin 34. When it stops, the second local pressure pin 35 also stops, and the pushing of the resin ends. In this way, even if the inside of the cavity 21 is blocked from the runner 19 and the resin in the cavity 21 contracts with cooling after the filling of the resin is cut off, the resin of the disposal boss portions 21a and 21b is put into the cavity 21. Since it can be pushed in, the pressure inside the mold in the cavity 21 can be made uniform, and sink can be prevented from occurring at the flow end.

Also, with respect to the effective stroke L _{D of} the first local pressure pin 34 disposed facing the cavity 21 via the gate 20, the second local pressure pin 34 is disposed at a position distant from the gate 20. Effective stroke L _C of local pressure pin 35
There to become shorter by the play L _B content, become overfilled is prevented. The length of the disposal bosses 21a and 21b is changed according to the shape of the molded product, and is set to be long at a place where sink marks are likely to occur and short at a place where sink marks are unlikely to occur.
In this case, for example, the adjustment can be made by inserting a washer (not shown) into the base of the second local pressure pin 35.

Next, a second embodiment of the present invention will be described. FIG. 4 is a state diagram of a local pressurized injection molding machine according to a second embodiment of the present invention before local pressurization, and FIG.
It is a state figure after local pressurization of the local pressurization type injection molding machine in an example of. 4A and 5A are cross-sectional views of the vicinity of the cavity, and FIGS. 4B and 5B are diagrams of the mold internal pressure characteristics at each position of the resin flow path. In FIGS. 4 and 5 (b), the vertical axis indicates the in-mold pressure, and the horizontal axis indicates the position.

In the figure, 18 is a sprue, 19 is a runner, 21 is a cavity, 34 is a first local pressure pin, 35
Is a second local pressure pin, 51 is an overlap type gate,
52 is a boss portion of the cavity 21. in this case,
The first local pressurizing pins 34 faces the gate 51, although the gate cutting when advancing, the effective stroke L _E of the first local pressurizing pins 34 is shorter, the boss portion discarded in front of the first local pressurizing pins 34 Is not formed. Therefore, there is no function of pushing the resin into the first local pressure pin 34 into the cavity 21.

By the way, the boss 5 is provided in the cavity 21.
When the molded product (not shown) is large and thick, such as when
Insufficient resin in the thick part inside, causing sink marks. That is, as shown in FIG.
When the connection between the runner 19 and the runner 19 is point a, the end of the runner 19 is point b, the gate is point c, and the end of the flow in the cavity 21 is point d, FIG. As shown, since the boss 52 is formed at the point d, the resin of the boss 52 shrinks and the shrinkage increases. Therefore, the resin is insufficient, and the in-mold pressure decreases as shown by the lines M ₁ and M ₂ , causing sink marks at the point d.

Therefore, the second local pressure pin 35 is connected to the boss 5
2 and the resin of the disposal boss portion 21b in front of the second local pressure pin 35 can be pushed into the cavity 21 when it is advanced, as shown in FIG. I have. The first and second local pressure pins 34 and 35 are
Different effective stroke L _E, is set to have the L _F. In this case, the rear end of the second local pressure pin 35 is sandwiched and fixed between the pressure plates 36 and 37 (FIG. 1), and the effective stroke L _{F of} the second local pressure pin 35 is adjusted.
The same value as the movement stroke L _A of the pressure plate 36, 37.

On the other hand, a play L _G is formed at the rear end of the first local pressure pin 34. Accordingly, the effective stroke L _E of the first local pressurizing pins 34 becomes _{L E = L F -L G =} L A -L G.

As described above, since the effective stroke L _E of the first local pressure pin 34 is shorter than the effective stroke L _F of the second local pressure pin 35, the second stroke before the gate cut is performed.
The local pressure pin 35 starts to advance, and the resin of the disposal boss 21b is pushed into the cavity 21 by the second local pressure pin 35 with the gate 51 opened. In this case, since the molded article is large, the resin does not flow back through the gate 51.

Accordingly, as the second local pressure pin 35 advances, the resin of the discarded boss 21b is removed from the cavity 21.
5B, the internal pressure of the mold in the cavity 21 can be made uniform as shown in FIG. 5B, and the occurrence of sink marks in the thick portion can be prevented. Next, a third embodiment of the present invention will be described.

FIG. 6 is a diagram showing a state before a local pressurization of a local pressurized injection molding machine according to a third embodiment of the present invention, and FIG. 7 is a view showing a local pressurized injection molding machine according to the third embodiment of the present invention. It is a state diagram after pressurization. 6A and 6A are cross-sectional views of the vicinity of the cavity, and FIGS. 6B and 7B are diagrams of the mold inner pressure characteristics at each position of the resin flow path. In FIGS. 6 and 7B, the vertical axis indicates the in-mold pressure, and the horizontal axis indicates the position.

In the figure, 18 is a sprue, 19 is a runner, 21 is a cavity, 34 is a first local pressure pin, 3
Reference numerals 5 and 54 denote second local pressure pins, and 53 denotes an overlap type gate. In this case, the first local pressure pin 34 faces the gate 53 and cuts the gate when it advances.
The effective stroke L _H of the first local pressure pin 34 is short, and no boss is formed in front of the first local pressure pin 34. Therefore, there is no function of pushing the resin into the first local pressure pin 34 into the cavity 21.

If the molded product (not shown) is large and box-shaped, the resin in the side wall portion in the cavity 21 is insufficient, and the side wall of the molded product is not balanced due to unbalance of linear shrinkage. Occurs. That is, as shown in FIG. 6A, the connection between the sprue 18 and the runner 19 is defined as a point a, and the end of the runner 19 is defined as a point b.
When the gate is at point c, the flow end in cavity 21 is at point d, and the side wall is at point e, FIG.
As shown in the figure, at the point e, the resin is insufficient, and the line M ₃ ,
Reduces the internal mold pressure as indicated by M _4, Uchizori occurs on the side wall of the molded article.

Therefore, the second local pressure pins 35 and 54 are disposed facing the corners in the cavity 21 and, as shown in FIG. The resin of the disposal boss portions 21b and 21c in front of the bosses 35 and 54 can be pushed into the cavity 21. The first and second local pressure pins 34, 35, 54
Are set to have different effective strokes L _H , L _I , and L _J. In this case, the rear end portion of the second local pressurizing pins 35 and pinched fixed by the pressure plate 36, 37 (FIG. 1), the effective stroke L _I of the second local pressurizing pins 35 pressure plate 36 , the same value as the movement stroke L _a of 37.

On the other hand, the first local pressure pin 34 and the second
A play is formed at the rear end of the local pressure pin 54, and the effective strokes L _H , L _I , and L _J are such that L _I > L _J > L _H. As described above, since the effective stroke L _H of the first local pressure pin 34 is shorter than the effective stroke L _I of the second local pressure pin 35, the second local pressure pin 35 moves forward before the gate is cut. Starting, the resin of the disposal boss 21b is pushed into the cavity 21 by the second local pressure pin 35 with the gate 53 opened. In this case, since the molded product is large, the resin does not flow back through the gate 53.

Further, since the effective stroke L _I of the second local pressure pin 35 is longer than the effective stroke L _J of the second local pressure pin 54, the amount of resin to be pushed in increases at the corners away from the gate 53. be able to. Therefore, the resin of the disposal bosses 21b, 21c is pushed into the cavity 21 with the advance of the second local pressure pins 35, 54, so that the mold internal pressure in the cavity 21 is increased as shown in FIG. It is possible to prevent the occurrence of inner sled due to unbalance of linear shrinkage on the side wall of the molded product.

The present invention is not limited to the above embodiments, but can be variously modified based on the gist of the present invention, and these are not excluded from the scope of the present invention.

[0047]

As described above in detail, in the local pressurized injection molding method of the present invention, the first local pressurized pin is advanced to push the resin in front of the first local pressurized pin into the cavity. The second local pressure pin is advanced to push the resin in front of the second local pressure pin into the cavity, and the timing of starting the advance of the first local pressure pin and the timing of the second local pressure pin The timing to start moving forward is made different.

Therefore, the resin injected from the injection nozzle is filled into the cavity through the gate, and at this time, the resin is also filled in front of the first local pressure pin and the second local pressure pin. Then, one of the first local pressure pin and the second local pressure pin advances, and thereafter, the other of the first local pressure pin and the second local pressure pin starts to advance. At this time, the other of the first local pressure pin and the second local pressure pin pushes the front resin into the cavity.

Therefore, even if the molded product is large or thick, there is no shortage of resin at the flow end portion or thick portion in the cavity, and sink occurs. In addition, it is possible to prevent the occurrence of inner sled due to the imbalance of linear contraction. In the local pressurized injection molding machine of the present invention, a fixed mold, a movable mold that is disposed so as to be able to freely contact and separate from the fixed mold and forms a cavity between the two, and penetrates the movable mold. A first local pressure pin extends and has a tip facing the cavity, and a second local pressure pin extends through the movable mold and has a tip facing the cavity.

Further, there is provided a pressure plate for supporting rear ends of the first local pressure pin and the second local pressure pin. The pressure plate forms a play at at least one of the rear ends of the first local pressure pin and the second local pressure pin, so that the effective stroke of the first local pressure pin and the second local pressure pin can be adjusted. Different effective stroke of pressure pin. Therefore,
The resin injected from the injection nozzle is filled into the cavity through the gate, and at this time, the resin is also filled in front of the first local pressure pin and the second local pressure pin.

When the pressing plate starts to advance, one of the first local pressing pin and the second local pressing pin advances, and when the pressing plate advances by an amount corresponding to the play, the first local pressing pin advances. The other of the local pressure pin and the second local pressure pin starts to move forward. At this time, the other of the first local pressure pin and the second local pressure pin pushes the resin in front into the cavity.

Therefore, even if the molded article is large or thick, there is no shortage of resin at the flow end portion or thick portion in the cavity, and sink occurs. In addition, it is possible to prevent the occurrence of inner sled due to the imbalance of linear contraction.

[Brief description of the drawings]

FIG. 1 is a sectional view of a local pressurized injection molding machine showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a state before a local pressurization of the local pressurized injection molding machine according to the first embodiment of the present invention.

FIG. 3 is a state diagram after local pressurization of the local pressurized injection molding machine according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a state before a local pressurization of a local pressurized injection molding machine according to a second embodiment of the present invention.

FIG. 5 is a view showing a state after a local pressurization of a local pressurized injection molding machine according to a second embodiment of the present invention.

FIG. 6 is a view showing a state before a local pressurization of a local pressurized injection molding machine according to a third embodiment of the present invention.

FIG. 7 is a view showing a state after a local pressurization of a local pressurized injection molding machine according to a third embodiment of the present invention.

[Explanation of symbols]

12 fixed mold 14 movable mold 20 gate 21 cavity 34 first local pressurizing pins 35 second local pressurizing pins 36 and 37 the pressure plate L _B play L _C, L _D effective stroke

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-47576 (JP, A) JP-A-6-99461 (JP, A) JP-A 5-425 (JP, A) JP-A-60-1985 151013 (JP, A) JP-A-58-131041 (JP, A) JP-A-58-179625 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 45 / 56-45 / 57,45 / 37-45/38

Claims (2)

(57) [Claims] (A) A first local pressure pin is advanced to push resin in front of the first local pressure pin into a cavity, and (b) a second local pressure pin is advanced to advance a second local pressure pin. While pushing the resin in front of the pressure pin into the cavity,
(C) A local pressurization type injection molding method, wherein a timing at which the first local pressurizing pin starts to advance and a timing at which the second local pressurizing pin starts to advance are made different. 2. A fixed mold, (b) a movable mold that is disposed so as to be able to contact and separate from the fixed mold and forms a cavity therebetween, and (c) penetrates the movable mold. A first local pressure pin having a tip facing the cavity, (d) a second local pressure pin extending through the movable mold and having a tip facing the cavity, and (e) a second local pressure pin having a tip facing the cavity. A pressure plate for supporting rear ends of the first local pressure pin and the second local pressure pin; and (f) the pressure plate includes the first local pressure pin and the second local pressure pin. A local pressurized injection molding machine characterized in that a play is formed at at least one rear end of the pin so that the effective stroke of the first local pressurized pin and the effective stroke of the second local pressurized pin are different.