JP2001096586A - Injection mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection mold not generating mold release inferiority in a molded article having a deep shaped part accompanied by large shrinkage or distortion in the design surface of the molded article at a time of the release of the molded article from a mold. SOLUTION: An injection mold consists of a fixed mold 2 and a movable mold 3 forming a cavity 4 in a mold clamping state and a plurality of ejector pins 18, 19, 20 for ejecting a molded article 5 to the outside from the cavity are provided on the side of the movable mold 3 and ejector plates 9, 10 are provided at front and rear positions on the side of the movable mold 3 so as to be advanced by utilizing the force given by an ejector rod 21 at a time of the mold opening operation of a molding machine and the ejector pins 18, 19, 20 are attached to the ejector plate 9 at the front position and a piston constituting part 13 having the pistons 14, 15 connected to the ejector pins 18, 19 at the positions corresponding to the ribs 5b, 5c of the molded article 5 among those ejector pins so as to allow them to advance and retreat is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction of an injection mold.

[0002]

2. Description of the Related Art As a method of injection molding a resin, a pair of molding dies (fixed mold and movable mold) which form a cavity inside in a mold-clamped state are used, and a molten cylinder is injected into the cavity from a heating cylinder. After filling and cooling and solidifying the filled resin, a method of opening the mold and taking out the molded product to the outside of the mold is general. In such an injection molding method, a plurality of ejector pins are often used as a mechanism for projecting a molded product from a cavity when a mold is opened.

Conventionally, in order to adjust the timing of ejecting the ejector pins with respect to the molded product, the ejector pins are mounted on an ejector plate, and the ejector plate is moved in accordance with the movement of the movable die. The ejector pins were to be protruded at the same time.

[0004]

However, some molded products have a plurality of ribs having different depths, and these ribs are located between the ejector pin and the tip of the rib due to shrinkage of the resin during the cooling time. There is a gap in Further, since the size of the gap varies depending on the depth of the rib, as shown in FIG. 6, when a plurality of ejector pins 23, 24 and 25 attached to the ejector plate 22 are simultaneously protruded, a Ribs 26b, 26c
Since the protrusion amount differs between the space and the top portion 26a, a mold release failure occurs in the ribs of the molded product 26, and the entire molded product 25 is distorted. Such distortion causes whitening and cracks on the top surface 26a of the molded product.

Conventionally, as disclosed in Japanese Patent Application Laid-Open No. 09-109198, there has been developed an injection molding die for changing the ejection timing of any one of a plurality of ejector pins depending on a part of a molded product. ing. In this mold, two sets of ejector plates are provided at front and rear positions, and a plurality of ejector pins are separately mounted on these ejector plates.
Even with the mold having this configuration, the amount of protrusion in advance cannot be changed according to the depth of the rib of the molded product,
The above problems cannot be solved.

Therefore, in the present invention, even when a molded product having a deep shape portion accompanied by large shrinkage is released from a mold, it may cause poor mold release or distortion of the design surface of the molded product. The aim was to provide no injection molds.

[0007]

In order to achieve the above-mentioned object, an injection molding die according to the present invention comprises a fixed die and a movable die having a cavity formed therein in a clamped state. In an injection molding die provided with a plurality of ejector pins for projecting a molded product from the cavity to the outside, a plurality of ejector plates are provided on the movable mold side so that a mold opening operation of the molding machine or an ejector of the molding machine is performed. The ejector plate is provided at the front and rear positions so as to be advanced using the force given by one or both of the rods, and all or some of the plurality of ejector pins are attached to the ejector plate at the front position. Along with
A piston component is provided which is provided with a piston linked to the ejector pin at a position corresponding to the deeply-shaped portion of the molded product in the ejector pin so that the piston can move forward and backward. By being advanced with the advance of the plate, the corresponding ejector pins are each advanced in advance in accordance with the amount of contraction of the molded product in the deep shape portion.

In the above-described injection molding die of the present invention, the movable die is displaced when the die is opened, and either or both of the mold opening operation of the molding machine and the ejector rod of the molding machine accompanying the displacement of the movable die. Using the applied force, the ejector plate at the rear position is first advanced. The ejector plate at the rear position is brought into contact with the ejector plate at the front position by the advance thereof, but is brought into contact with the piston of the piston component in advance before the contact surface with the ejector plate at the front position. Then, the ejector pin associated with this piston is advanced.

In this case, the corresponding advance stroke of the ejector pin is adjusted to the amount of shrinkage in the deeply formed part of the molded article such as a rib of the molded article. The ejector pin is brought into contact with the ejector pin. Therefore, when the ejector plate at the rear position comes into contact with the ejector plate at the front position,
The corresponding ejector pin projects with respect to the molding at the same time as the other ejector pins. Thereafter, the ejector plates at these front and rear positions are integrally advanced, and the plurality of ejector pins act so as to simultaneously project the molded product.

Further, the number of the corresponding ejector pins depends on the number of the deep molded portions of the molded product, and therefore may be singular or plural. When a plurality of the corresponding ejector pins are provided, a piston component provided with a piston associated with each of the ejector pins is provided. In such a piston component, each ejector pin is set at a different timing so that each piston moves forward so that a forward stroke corresponding to the amount of contraction of a deep molded portion of the corresponding molded product is obtained. Is done.

Next, in the present invention, an ejector pin may be attached to an ejector plate at a rear position. According to this configuration, the ejector plate at the rear position is first advanced by the first stroke, and then the ejector plates at the front and rear positions are integrally advanced by the second stroke. Since the ejection is performed by the ejector pins, the first stroke may be set to the minimum stroke necessary for releasing the molded product. Therefore, regardless of the depth of the molded part of the molded product, the length of the ejector pin and the advance stroke can be shortened, and even if the molded product has a large release resistance, the release resistance is divided into stages and released. The molded product can be protruded while reducing the mold resistance.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings. The injection molding die 1 shown in FIG. 1 comprises a fixed die 2 and a movable die 3 that form a cavity 4 inside in a clamped state, and a molded product 5 is moved from the cavity 4 to the outside on the movable die 3 side. A plurality of ejector pins 18, 19, and 20 for projecting are provided, and the ejector plates 9, 10 are advanced on the movable mold 3 side by using a force given by an ejector rod 21 during a mold opening operation of the molding machine. The ejector plate 9 at the front position among the ejector pins 18 is
The piston 1 is provided with the ejector pins 19 and 20 and the ejector pins 18 and 19 at positions corresponding to the ribs 5b and 5c of the molded product 5 among these ejector pins.
There is provided a piston component 13 having four and 15 capable of moving forward and backward. Reference numeral 5a denotes a top portion of the molded product 5 formed in the cavity 4. The fixed mold 2 is attached to the mold apparatus via the mounting plate 6, and the movable mold 3 is attached to the mold device via the mounting plate 7.

The ejector plate 9 at the front position and the ejector plate 10 at the rear position are inserted and supported by the ejector guides 8, 8 passed into the cavity 3 a in the movable mold 3, and follow these guides 8. It is slidably mounted. The ejector plates 9 and 10 are urged by a spring 11 provided therebetween,
The ejector plate 9 is urged by a spring 12 provided between the ejector plate 9 and the inner wall of the cavity 3a. The biasing forces of these springs 11 and 12 act so that the ejector plates 9 and 10 return to the rearmost positions, respectively.

The piston constituting section 13 is provided with the pistons 14 and 15 as described above. One end of an ejector pin 18 is connected to the piston 14, and one end of an ejector pin 19 is connected to the piston 15 respectively. I have.
The other ends of these ejector pins 18 and 19 are
Are slidably inserted into ejector holes 4a communicating with the cavities 4 which are respectively in contact with the ribs 5b, 5c. One end of the ejector pin 20 is disposed on the ejector plate 9, and the other end of the
It is slidably inserted into the ejector hole 4a that is in contact with the a-plane.

As shown in FIG. 2, the pistons 14 and 15 are disposed in cylinders 9a and 9b formed by holes formed in the ejector plate 9 so as to be able to move forward and backward, respectively. The springs 16 having one ends locked to the front edges of the front ends 9a and 9b are urged to be at the rearmost positions, respectively. The rearmost positions of the pistons 14 and 15 correspond to the ejector pins 1
Retreat stoppers 17 are respectively provided on 8 and 19, and the retreat stoppers 17 are locked to the surface of the ejector plate 9, respectively, thereby restricting the retreat. The ejector pins 18 are provided corresponding to the ribs 5b, and the ejector pins 19 are provided corresponding to the ribs 5c. The ribs 5b are formed portions of the molded product 5 deeper than the ribs 5c.

FIG. 1 shows the state at the time when the molten resin is injected and filled into the cavity 4 and the filled resin is cooled and solidified. At this point, as shown in FIG.
The b and the rib 5c shrink during solidification, and gaps l ₁ and l ₂ are formed between the ejector pins 18 and 19 in the ejector pin hole 4a. This gap l
_1, l ₂ of the piston 14, 15 according to the size rearward end 14a, 15a projecting position of is set in advance.
That protrudes stroke L ₁ from the rear end 14a to the rear face of the ejector plates 9 are matched corresponding to the gap l ₁ ,, The ejector from the rear end 15a plates 9
Projecting stroke L ₂ up towards match corresponding to the gap l ₂ after. The protruding stroke is L ₁
> From the relation of L _2, the rear end 14a is rearward end 15a
It is located further back.

Also, the ejector plates 10 are in contact with the end portions of the ejector rods 21 and 21 from the molding machine into which the mounting plate 7 is inserted through the through holes 7a. Therefore, when the movable mold 3 retreats when the mold is opened, as shown in FIG. 3, each ejector rod 21 relatively pushes out the ejector plate 10 and moves forward in a direction opposite to the moving direction of the movable mold 3. The ejector plate 10 which has been advanced in this way first comes into a collision state with the piston 14, and the ejector hole 4 of the ejector pin 18 associated therewith.
The advance into a is started.

Next, the ejector plate 10
Is pushed, the piston 15 comes into a collision state, and the associated ejector pin 19 starts to advance into the ejector hole 4a. Finally, as shown in FIG. 4, the ejector plate 10 and the ejector plate 9 Are in contact with each other. At this time, the pistons 14 and 15 are advanced forward by the above-described protruding stroke, and the ejector pins 18 and 19 are protruded in advance by the operating stroke, and the tips of the ejector pins 18 and 19 are respectively 5b and 5c come into contact with the ends.

Next, as shown in FIG. 5, when the movable mold 3 further retreats and the ejector plate 10 and the ejector plate 9 are pushed together by the ejector rod 21, the ejector pins 18, 19 and 20 are ejected. The molded product 5 is protruded out of the cavity 4 in a state where the molded product 5 comes into contact with the ribs 5b and 5c and the top 5a of the molded product 5 at the same time. In this case, each ejector pin 18, 19 and 20
Therefore, the molded product does not cause mold release failure or distortion.

When the movable mold 3 returns to the initial clamped state, the pushing action by the ejector rod 21 is released, and the ejector plates 9 and 10 return to their original positions by the urging action of the springs 11 and 12, respectively. .
Further, the piston 14 is actuated by the biasing action of the spring 16.
As 15 returns to its original position, the ejector pins 18, 19 and 20 also return to their original positions.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Using an injection mold of the embodiment shown in FIG.
The cavity was injection-filled with molten polypropylene to form a molded article. The molding has ribs with a depth of 300 mm and 150 mm. The shrinkage of this resin is 1
7/1000, the maximum shrinkage is 5.1 mm for a 300 mm deep rib and 2.6 for a 150 mm deep rib.
However, since it is assumed that contraction of about 80% of the maximum contraction amount has been completed at the time of taking out from the cavity, the distance between the ejector pin and the tip of the corresponding ejector pin is 4.1 mm and 2 mm, respectively. A gap of .1 mm is generated. In accordance with these gaps, the working strokes of the pistons associated with the respective ejector pins are set to 4.1 mm and 2.1 mm.
The piston component incorporates the retraction stopper and spring set in the above.

As described above, the molded product obtained by setting the working stroke of each piston and projecting by each ejector pin does not cause mold release failure at the time of projecting, and also causes whitening or cracking of the molded product due to distortion. A molded article having an excellent appearance without generation of a powder was obtained.

[0023]

Since the invention is configured as described above,
The following effects are exhibited. First, the injection mold of the present invention comprises a fixed mold and a movable mold in which a cavity is formed inside in a mold-clamped state, and a plurality of ejectors for projecting a molded product from the cavity to the outside on the movable mold side. In the injection mold provided with a pin, a plurality of ejector plates are provided on the movable mold side by using a force given by one or both of an opening operation of a molding machine and an ejector rod of the molding machine. All or some of the plurality of ejector pins described above are attached to the ejector plate at the forward position among the ejector plates at the front position of the ejector plate. A piston component is provided which is provided with a piston linked to an ejector pin at a corresponding position so as to be able to move forward and backward. Since the tongue is advanced with the advance of the ejector plate in the rear position, the corresponding ejector pins are each advanced in advance in accordance with the amount of contraction in the deep shape portion of the molded product, It is possible to prevent a mold release defect due to a timing deviation at the time of mold release, the occurrence of whitening and cracks in the molded product, and to obtain a molded product having good appearance.

Further, the functional operation on the piston, the ejector pin and the like is executed by using the force given by one or both of the mold opening operation of the molding machine and the ejector rod of the molding machine at the time of the moving operation of the movable die. Therefore, the mold release can be performed in a well-balanced manner, the reliability of the mold can be improved, and other drive devices such as a hydraulic cylinder and a control device therefor are not specially required. Further, since the molding cycle does not elongate, the cost of the molded product does not increase.

Further, according to the configuration in which the ejector pins are also attached to the ejector plate at the rear position, the sliding stroke of the ejector pins is short, so that a molded product having a deep molded portion can be formed. In addition, the buckling of the ejector pins and the friction of the ejector holes are reduced, so that it is possible to prevent burrs and the like from being generated in the molded product.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional front view of an injection molding mold according to the present invention when the mold is clamped.

FIG. 2 is a vertical cross-sectional front view of the above-described injection mold at the start of mold opening.

FIG. 3 is a vertical cross-sectional front view of the injection molding die during opening of the same.

FIG. 4 is a vertical cross-sectional front view of the above-described injection mold during opening of the mold.

FIG. 5 is a vertical sectional front view of the injection molding die when the molded product is protruded when the mold is opened.

FIG. 6 is a partial vertical cross-sectional front view when a molded product is protruded in a case of using an injection mold having a conventional configuration.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Injection mold 2 Fixed mold 3 Movable mold 4 Cavity 5 Molded product 5a Fillet 5b, 5c Rib 9 Ejector plate in front position 10 Ejector plate in rear position 13 Piston component part 14, 15 Piston 18, 19, 20 Ejector pin 21 ejector rod l _1, l ₂ gap

Claims (2)

[Claims] Injection molding comprising a fixed mold and a movable mold in which a cavity is formed inside in a mold clamped state, and a plurality of ejector pins for projecting a molded product from the cavity to the outside on the movable mold side. In the mold, a plurality of ejector plates are moved forward and rearward on the movable mold side such that the ejector plates are advanced using a force given by one or both of a molding machine opening operation and an ejector rod of the molding machine. The whole or a part of the plurality of ejector pins described above is attached to the ejector plate at the front position among the ejector pins, and the ejector pin at the position corresponding to the deep shape portion of the molded product among the ejector pins is attached to the ejector plate. A piston component provided with an associated piston so as to be able to move forward and backward, wherein the piston of the piston component is in the rear position Injection molding metal, wherein the ejector pins are advanced in advance in accordance with the advance of the ejector plate, whereby the corresponding ejector pins are advanced in advance in accordance with the amount of contraction of the molded product in the deep shape portion. Type. 2. The injection mold according to claim 1, wherein an ejector pin is also attached to an ejector plate at a rear position.