JPH09136338A - Mold apparatus for molding reticulated body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of a short shot and the formation of a weld line in a molding. SOLUTION: An apparatus has a fixed mold 31, a movable mold 34 which forms a cavity space 41 equipped with a mesh part 11 and a fringe part 13 between it and the fixed mold 31, pins which are arranged to face spots of the fringe part 13 and to be able to move forward and backward freely, and a controller. The controller is equipped with a resin flow controlling means which in an injection process, moves the pins forward at a set time before a resin reaches the fringe part 13 to cut off the resin flow in the fringe part 13 and moves the pins backward at another set time. Before the injected resin, which entered a mesh part 11, reaches the fringe part 13, the pins are moved forward to cut off the resin flow in the fringe part 13 so that the resin which reached the fringe part 13 flows in the fringe part 13, preventing the resin from entering the mesh part 11 again from another part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold device for forming a mesh body.

[0002]

2. Description of the Related Art Conventionally, in an injection molding machine, a resin heated and melted in a heating cylinder is filled into a cavity space of a mold, and the resin is cooled and solidified in the cavity space. The mold is opened and the molded product is taken out. By the way, in the case of molding a molded product composed of a rimmed net-like body, a net-like body molding die device as shown in FIG. 2 is used.

FIG. 2 is a plan view of a conventional mesh body molding die device. In the figure, 11 is a mesh portion, 12 is a "ten" -shaped dielectric portion formed in the central region of the die, 13 is an edge portion formed on the periphery of the mesh portion 11, and 21 is a gate. The resin supplied from a sprue (not shown) enters the dielectric portion 12 through the gate 21 and the dielectric portion 12
Enters the mesh portion 11 from.

[0004]

However, in the above-mentioned conventional net body molding die device, a short shot occurs in a molded product or a weld line is formed. FIG. 3 is a diagram showing an initial flow pattern in a conventional mesh body molding die apparatus, FIG. 4 is a diagram showing an intermediate period flow pattern in a conventional mesh body molding die apparatus, and FIG. 5 is a conventional mesh body. It is a figure which shows the final flow pattern in a metal mold | die apparatus for molding.

The resin supplied from a sprue (not shown) enters the dielectric portion 12 through the gate 21 (FIG. 2) and enters the mesh portion 11 from the dielectric portion 12. Since the flow path resistance applied to the resin is smaller than that of the mesh portion 11 in the dielectric portion 12, the resin has four branch portions 12a to 12d.
After flowing at a high speed inside, it flows at a low speed in each of the capillary channels forming the mesh portion 11. Therefore, the initial flow front F1 that has begun to enter the mesh portion 11 is, as shown in FIG.
Form a uniform flow pattern that is approximately a "10" shape.

However, since the resin after filling the inside of the four branch portions 12a to 12d mainly flows out from the tips of the respective branch portions 12a to 12d, most of the resin that has entered the mesh portion 11 is , The amount of resin flowing in the direction of arrow A along the capillary flow path communicating with the tips of the branch portions 12a to 12d, while flowing in the direction perpendicular to arrow A, decreases. Therefore, as shown in FIG. 4, the flow front F2 in the intermediate period has eight projecting portions 23 and forms an uneven flow pattern in which the unfilled portions 22 are formed between the projecting portions 23. . Then, the resin flowing in the capillary channels of each of the protruding portions 23 precedes the edge portion 13 before the resin flowing in the direction perpendicular to the arrow A.
When it reaches the position, it flows in the direction of arrow B along the edge portion 13.

By the way, since the edge portion 13 is formed thicker than the mesh portion 11, the flow path resistance at the edge portion 13 is small. Therefore, when the resin reaches the edge portion 13, more resin flows only in the direction of the arrow A, so that the resin adjacent to the unfilled portion 22 stagnates. And the edge 1
The resins flowing in the direction of arrow B in FIG. 3 collide with each other and then enter the mesh portion 11 in the direction of arrow C from the edge portion 13 as shown in FIG.

Therefore, the final flow front F3
Forms a flow pattern having a plurality of air pockets 25 at positions adjacent to the edge portion 13 in the mesh portion 11. As a result, the air pocket 25 remains,
Short shots occur in the molded product. Further, even if the generation of the air pocket 25 can be eliminated, a weld line is formed by the merging of the resin, which not only lowers the strength of the molded product by that amount but also deteriorates the quality.

The present invention solves the problems of the conventional mold apparatus for forming a mesh body, and does not cause a short shot or a weld line in the molded product. It is an object to provide a mold device.

[0010]

Therefore, in the reticulated body molding die apparatus of the present invention, a cavity space having a mesh portion and an edge portion is provided between the fixed die and the fixed die. It has a movable mold to be formed, a pin which is arranged so as to move forward and backward so as to face a plurality of positions of the edge portion, and a control device.

The control device advances the pin at a set timing until the resin reaches the edge portion in the injection process, interrupts the flow of the resin in the edge portion, and at another set timing. A resin flow control means for retracting the pin is provided. In another net-shaped body molding die device of the present invention, the pin is an ejector pin.

[0012] In still another mesh body molding apparatus of the present invention, a runner-shaped dielectric portion is further formed at the center of the mesh portion. In still another mesh body molding apparatus of the present invention, the pin is further retracted when the time counting by the timer is completed. In still another mesh body molding apparatus of the present invention, the pin is further retracted when the screw of the injection device reaches the set position.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a cross-sectional view of a mesh body molding die device according to a first embodiment of the present invention. In the figure, 30 is a fixed platen, 31 is a fixed mold, 32 is the fixed mold 31,
It is a fixed side mounting plate for mounting on.

In this case, in the injection step, the injection nozzle of an injection device (not shown) is advanced and the tip of the injection nozzle is brought into contact with the sprue bush 38a. On the other hand, the movable platen 33 is moved in the left-right direction in the drawing by a mold clamping device (not shown) to bring the movable mold 34 into contact with and separate from the fixed mold 31. Therefore, the movable mold 34 is fixed to the movable platen 33 via the receiving plate 29, a spacer block (not shown), and the movable side mounting plate 35.

Then, the resin injected from the injection nozzle passes through the sprue 38 and the gate 21, and is fixed to the fixed mold 31.
Space 41 formed between the mold and the movable mold 34
Is filled. In this case, the cavity space 41
Is composed of a mesh portion 11, a runner-like dielectric portion 12 and an edge portion 13. Further, when the injection process is completed, the pressure holding process and the cooling process are subsequently started, the resin pressure in the cavity space 41 is held, and the resin is cooled.

After a preset time has elapsed, the movable mold 34 is moved to the left in the drawing with a molded product (not shown) left on the movable mold 34 side, and the mold is opened. At this time, the molded product is pushed down by an ejector device (not shown). Therefore, the first ejector pin 45 is provided so as to face the dielectric portion 12, and the second ejector pin 46 is provided so as to face the edge portion 13. A head portion 43 is formed near the rear end of the first ejector pin 45, and a head portion 44 is formed at the rear end of the second ejector pin 46. The head portion 43 is slidably housed in a housing chamber 65 formed between the ejector plates 51 and 52, and moves relative to the ejector plates 51 and 52. On the other hand, the head portion 44 is sandwiched and fixed by the ejector plates 51 and 52. Then, a rod 50 is disposed so as to be movable back and forth behind the ejector plates 51 and 52, and when the rod 50 is moved forward by a hydraulic cylinder (not shown), the ejector plates 51 and 52 are moved forward, and further, the first The ejector pin 45 and the second ejector pin 46 are moved forward and ejected from the movable mold 34, and the molded product is ejected. The hydraulic cylinder is moved forward by electrically operating a proportional solenoid valve and a switching valve of a hydraulic circuit (not shown). The proportional solenoid valve and the switching valve are controlled by a controller (not shown).

When the release of the molded product is completed in this way, the first ejector pin 45 and the second ejector pin 46 are retracted. Therefore, a return pin 61 is disposed so as to face the fixed mold 31, and the head portion 63 at the rear end of the return pin 61 is sandwiched and fixed by the ejector plates 51 and 52. A return spring 62 is arranged between the return pin 61 and the receiving plate 29.

When the rod 50 is at the retracted limit position, the ejector plates 51 and 52 are biased rearward by the return spring 62, the ejector plate 52 is brought into contact with the movable side mounting plate 35, and the retracted limit position is set. Take. At this time, the front end surfaces of the return pin 61 and the second ejector pin 46 are both positioned slightly behind the parting line (PL), that is, the surface of the fixed mold 31, and the forward stroke S1 is It is formed. In the present embodiment, the forward stroke S1 is
It is made equal to the thickness of the edge 13.

Therefore, even during the mold closing process, by advancing the ejector plates 51 and 52,
The second ejector pin 46 can be advanced by the advance stroke S1. Further, the rod 50 penetrates the ejector plate 52, extends to the rear of the head portion 43, and faces the movable side mounting plate 35. Then, when the ejector plate 52 reaches the retracted limit position, the rear end of the first ejector pin 45 extending rearward from the head portion 43 contacts the movable side mounting plate 35, and the head portion 43 and the accommodating chamber 65. A play D1 is formed between the rear end face and the rear end face.

Therefore, even if the second ejector pin 46 is moved forward by the forward stroke S1 during the mold closing process, the first ejector pin 45 can be kept stopped. Next, the operation of the reticulated body molding die device having the above-described configuration will be described. FIG. 6 is a time chart showing the operation of the reticulated body molding die apparatus according to the first embodiment of the present invention, and FIG. 7 is a diagram showing a final stage flow pattern according to the first embodiment of the present invention.

In FIG. 7, 11 is a mesh portion, 12 is a "ten" -shaped dielectric portion formed in the central region of the die, and 13
Is an edge portion formed on the periphery of the mesh portion 11, and 21 is a gate. The resin (not shown) supplied from the sprue 38 (FIG. 1) enters the dielectric portion 12 through the gate 21,
The mesh portion 11 enters from the derivative portion 12. The dielectric portion 12 includes four branch portions 12a to 12d. Further, since the branch portions 12a to 12d function as a runner, the resin supplied from the sprue 38 flows at high speed through the branch portions 12a to 12d and enters the mesh portion 11. Therefore,
The time required for the resin to reach the entire cavity space 41 can be shortened.

By the way, since the resin after filling the inside of the four branch portions 12a to 12d mainly flows out from the tips of the respective branch portions 12a to 12d, most of the resin that has entered the mesh portion 11 is , Flows along the capillary channels communicating with the tips of the branches 12a to 12d, and reaches the regions AR1 to AR6 in the edge 13 before the resin flowing in the direction perpendicular to the flow.

In this case, when the resin that has reached the areas AR1 to AR6 first flows along the edge portion 13 and the resin wraps around from the other portion and enters the mesh portion 11 again, air pockets are formed. Will end up. Therefore, the second ejector pins 46 are arranged on both sides of each of the areas AR1 to AR6 where the resin reaches first. Therefore, by advancing the second ejector pin 46 before the resin reaches the areas AR1 to AR6, the resin that has reached the areas AR1 to AR6 earlier flows along the edge portion 13. Can be prevented.

In the reticulated body molding die apparatus having the above structure, first, the movable platen 33 is advanced to perform a mold clamping step, and then an injection step is started. In the injection step, the resin injected from the injection nozzle of the injection device (not shown) passes through the sprue 38 and enters the guide portion 12 and the four branch portions 12a.
To 12d, and mainly flows out from the tips of the branch portions 12a to 12d.

The resin flow control means of the control device (not shown) supplies oil to the hydraulic cylinder (not shown) at least at the set timing t1 before the resin reaches the areas AR1 to AR6, and the ejector plate 51 is supplied. ,
52 is advanced by the advance stroke S1. At this time, the second ejector pin 46 is advanced to surround both ends of the areas AR1 to AR6 and block the flow of the resin in the edge portion 13.

Therefore, the resin reaching the areas AR1 to AR6 will not flow along the edge portion 13,
It is possible to prevent the resin from wrapping around from other portions and entering the mesh portion 11 again. Then, the areas AR1 to AR1
After AR6 is filled, the resin advances in the direction of arrow D and fills the entire cavity space 41. As a result, air pockets do not occur, so that not only short shots can be prevented from occurring in a molded product (not shown), but also weld lines can be prevented from being formed.

Further, since the second ejector pin 46 is used to block the flow of the resin in the edge portion 13, there is no need to dispose another pin, and the mesh body molding die device can be simplified. Can be converted. Note that the ejector plates 51, 5 and 5 are cut off while the resin flow in the edge portion 13 is blocked.
2 moves forward while making the play D1 smaller, the first ejector pin 45 does not move forward. Further, since the rear end of the first ejector pin 45 is in contact with the movable side mounting plate 35, it does not move backward.

Then, the resin flow control means drains the oil in the hydraulic cylinder and retracts the second ejector pin 46 at another set timing t2 from the start to the end of the injection process. . Therefore, when the injection process is completed, the entire edge portion 13 is filled with the resin. In the present embodiment, the timing t2 is the time when the timer (not shown) has timed.
The timer is set so as to start timing when the injection process is started and finish timing when the delay time elapses.

The timing t2 may be the time when the screw of the injection device reaches a preset screw position. In this way, during the injection process, the injection device is controlled from speed control to pressure control at the timing (V / P switching point) when the resin pressure in the cavity space 41 reaches the set value. And the pressure-holding process starts. Then, a cooling process is performed to complete the molded product.

Subsequently, the mold opening process is started, and the movable platen 3
3 is retracted. At this time, the movable mold 34 is moved to the left in the drawing with the molded product left on the movable mold 34 side, and the mold opening is performed. Then, when oil is supplied to the hydraulic cylinder and the rod 50 is advanced, the ejector plates 51 and 52 are advanced, and further,
First ejector pin 45 and second ejector pin 4
6 is advanced and ejected from the movable mold 34, and the molded product is ejected.

Next, a second embodiment of the present invention will be described. FIG. 8 is a plan view of a mesh body molding die apparatus according to the second embodiment of the present invention. In the figure, 11
Is a mesh portion, 13 is an edge portion, 46 is a plurality of second ejector pins which are arranged at a plurality of positions of the edge portion 13 so as to face the edge portion 13 and can move back and forth, and 71 is a side gate.

In the injection process, the resin (not shown) that has entered the mesh portion 11 through the side gate 71 is
3, but even if a non-uniform flow pattern is formed in the mesh portion 11, by the second ejector pin 46 that is advanced at each position of the edge portion 13,
Since the flow of the resin in the edge portion 13 is blocked, the resin does not wrap around from other portions and enter the mesh portion 11 again.

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

[0034]

As described above in detail, according to the present invention, in the reticulated body molding die device, the fixed die,
A movable die that forms a cavity space having a mesh portion and an edge portion between the fixed die, a pin that is arranged so as to advance and retreat facing a plurality of positions of the edge portion, and a control device. Have.

Then, the control device advances the pin at a set timing until the resin reaches the edge portion in the injection process, shuts off the resin flow in the edge portion, and sets another setting. A resin flow control means for retracting the pin at a timing is provided. In this case, in the injection step, the resin injected from the injection device enters the mesh portion, the pin is advanced before reaching the edge portion, and the flow of the resin in the edge portion is blocked. The reached resin will not flow inside the edge.

Therefore, it is possible to prevent the resin from wrapping around from another portion and entering the mesh portion again, and the entire cavity space is filled with the resin. As a result, air pockets are not generated, so that not only short shots can be prevented from occurring in the molded product, but also weld lines can be prevented from being formed.

In another metal mold apparatus for molding a net according to the present invention, the pin is an ejector pin. In this case, since it is not necessary to dispose another pin to block the flow of the resin in the edge portion, the mesh body molding die device can be simplified. In still another mold device for molding a net-like body of the present invention, a runner-shaped derivative portion is further formed at the center of the mesh portion.

In this case, since the resin injected from the injection device flows into the mesh portion after flowing through the dielectric portion, the time required for the resin to reach the entire cavity space can be shortened.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a mesh body molding die device according to a first embodiment of the present invention.

FIG. 2 is a plan view of a conventional mesh body molding die device.

FIG. 3 is a diagram showing an initial flow pattern in a conventional mesh body molding die device.

FIG. 4 is a diagram showing a flow pattern in an intermediate period in a conventional mesh body molding die device.

FIG. 5 is a diagram showing a final-time flow pattern in the conventional mesh body molding die device.

FIG. 6 is a time chart showing the operation of the mesh body molding die device according to the first embodiment of the present invention.

FIG. 7 is a diagram showing a final stage flow pattern in the first embodiment of the present invention.

FIG. 8 is a plan view of a mesh body molding die device according to a second embodiment of the present invention.

[Explanation of symbols]

 11 mesh part 12 derivative part 13 edge part 31 fixed mold 34 movable mold 41 cavity space 45 first ejector pin 46 second ejector pin

Claims (5)

[Claims] 1. A movable die for forming a cavity space having a mesh portion and an edge portion between (a) a fixed die and (b) the fixed die; and (c) the edge portion. (D) The control device has a pin that is arranged to move forward and backward so as to face a plurality of locations, and (e) the control device has a set timing until the resin reaches the edge portion in the injection process. Advancing the pin to block the flow of resin in the edge,
A reticulated body molding die apparatus comprising resin flow control means for retracting a pin at another set timing. 2. The reticulated body molding die apparatus according to claim 1, wherein the pin is an ejector pin. 3. The reticulated body molding die device according to claim 1, wherein a runner-shaped dielectric portion is formed in a central portion of the mesh portion. 4. The reticulated body molding die apparatus according to claim 1, wherein the pin is retracted when the time counting by the timer is completed. 5. The reticulated body molding die apparatus according to claim 1, wherein the pin is retracted when the screw of the injection device reaches a set position.