KR101335530B1 - Injection mold for molding product having undercut - Google Patents

Abstract

Disclosed is an injection mold, capable of forming a product with an undercut which protrudes in a horizontal direction by injection molding, and taking out the product. A lower core of the disclosed injection mold comprises: a fixed block which is fixed and connected to a lower disc; a movement block which is movable between a first position in which an upper core and the lower core are closely attached to each other, and a second position in which an injection molded product molded in a cavity is taken out at the lower core; and an undercut formation block which contains an undercut groove corresponding to the shape of the undercut and is elastically compressed in order to be closely attached to the fixed block. One side of the fixed block is an inclined plane which is inclined with respect to the direction of an elastic pressing force applied to the undercut formation block. The undercut groove is formed to be separated from the undercut of the injection molded product by moving the undercut formation block to the inclined direction along the inclined plane of the fixed block when the movement block is moved to the second position from the first position.

Description

Injection mold for forming product with undercut {Injection mold for molding product having undercut}

The present invention relates to an injection molding die, and more particularly, to an injection molding die capable of injection molding a product having an undercut.

Injection molding is a method in which a molten resin is injected into a mold and cooled to form a product. Compared with other molding methods such as compression molding and extrusion molding, And the size is limited, and productivity and workability are excellent, and it is widely used for molding of plastic products.

In the field of injection molding, undercut is used as a term that refers to a part of a projection that protrudes in the horizontal direction of a product. Typical injection molded articles can be easily separated from the mold by separating the upper and lower cores of the mold after injection and curing of the molten resin. However, products with undercuts cannot be taken out intact from the injection molding mold by a simple method of separating the upper and lower cores. Therefore, a complicated injection molding mold is required.

Meanwhile, the conventional injection molding mold of the prior art further includes an upper fixing plate, a lower fixing plate, a mill plate, a mil pin, a spacer block, etc., in addition to the upper and lower cores forming the cavity, the upper disc and the lower disc supporting them. In addition to this, a sliding core and driving means thereof were further provided to easily take out the undercut of the product. This makes it difficult to reduce the size and thickness of injection molding molds and increases manufacturing costs.

The present invention provides an injection molding mold capable of injection molding and taking out a product having an undercut protruding in the horizontal direction.

The present invention provides an injection molding mold capable of injection molding and taking out a product having an undercut, while reducing the size and thickness by reducing members such as a mill plate, a pin, a spacer block, and a manufacturing cost.

According to the present invention, a cavity corresponding to a shape of an injection molded product having an undercut when the at least one of the two moves and moves closer to or away from each other and is in close contact with each other is formed. An upper core supported by the upper disc, and a lower core supported by the lower disc. The lower core may include a fixed block fixedly coupled to the lower disc, a first position that is a position when the upper core and the lower core are in close contact with each other, and the injection molded product molded from the cavity may be ejected from the lower core. It has a movable block movable between a second position which is a position at the time, and an undercut forming block which has an undercut groove corresponding to the shape of the undercut, and which is elastically pressed to be in close contact with the fixed block. One side of the fixed block in close contact with the undercut forming block is an inclined surface inclined inclined with respect to the direction of the elastic pressing force applied to the undercut forming block, and when the moving block is moved from the first position to the second position, the undercut forming block is The undercut groove may be configured to move away from the undercut of the injection molded article by moving in an inclined direction along the inclined surface of the fixing block.

The undercut forming block may be disposed on opposite sides of the side in which the undercut groove is formed and the side in close contact with the fixing block.

The moving block may be disposed outside the fixing block, the undercut forming block may be disposed between the fixing block and the moving block, and the undercut groove may be formed to have a concave recess shape toward the fixing block.

The moving block may be formed to surround the outer periphery of the fixed block, and include a plurality of block pieces coupled to each other.

The moving direction of the moving block and the direction of the elastic pressing force applied to the block for forming the undercut may be configured to be orthogonal.

The injection molding mold according to the embodiment of the present invention may be configured such that the injection molded product is spaced apart from the fixed block when the moving block moves from the first position to the second position.

The means for elastically pressurizing the undercut forming block to be in close contact with the fixed block includes a rod having one end coupled to the undercut forming block, and a rod inserted into the movable block so that the other end of the rod is inserted into the undercut forming block. It may be provided with a spring for elastically pressing toward the fixed block side.

The injection molding die according to the embodiment of the present invention may further include a moving block actuator supported on the lower disc by moving the moving block between the first position and the second position.

The injection molding die of the present invention further includes a blowout unit that separates and ejects the injection-molded product from the lower core when the upper core and the lower core are spaced apart from each other, and the blowout unit includes a high pressure air jet. ) Is inserted into the air jet flow passage extending to the lower core to guide the injection molded product, and an outer circumferential surface in close contact with the inner circumferential surface of the air jet flow passage, and concave toward the center from the outer circumferential surface. A body having a groove cut out and extending in parallel with an extending direction of the air jet flow path, the body having a diameter located closer to the cavity than the body and not in close contact with the inner circumferential surface of the air jet flow path Insertion part having a head and a neck connecting the body and the head and having a smaller diameter than the head. And a distance between an outer circumferential surface of the head and an inner circumferential surface of the air jet flow path may be 0.02 to 0.04 mm.

According to the injection molding metal mold | die of this invention, the product which has an undercut can be formed by injection molding, and it can separate easily and take out. Moreover, injection molding and ejection are easy not only when the undercut protrudes outward but also when the undercut protrudes inward.

In addition, the present invention is an injection-molding mold that can be ejected by injection molding a product having an undercut, and also removes the members such as a mill plate, a pin, a spacer block provided in the conventional injection molding mold to reduce the size and thickness and reduce the production cost Can be saved.

1 is a cross-sectional view of an injection molding mold according to an embodiment of the present invention.
FIG. 2 is a perspective view showing the moving block of FIG. 1 and the injection molded product before being taken out from it. FIG.
FIG. 3 is a perspective view showing the elastic pressing means of the undercut molding block provided in the injection molding die of FIG. 1. FIG.
4 to 6 are partial cross-sectional views sequentially illustrating a process in which the injection-molded product is separated out from the injection molding die of FIG. 1.
7 is a cross-sectional view of an injection molding mold according to another embodiment of the present invention.
8 is a perspective view illustrating the insertion member of FIG. 7.

Hereinafter, an injection molding die according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The terminology used herein is a term used to properly express the preferred embodiment of the present invention, which may vary depending on the intention of the user or operator or the custom of the field to which the present invention belongs. Therefore, the definitions of the terms should be made based on the contents throughout the specification.

1 is a cross-sectional view of an injection molding mold according to an embodiment of the present invention, Figure 2 is a perspective view showing the moving block of Figure 1 and the injection molded product before it is taken out, Figure 3 is in the injection molding mold of Figure 1 It is a perspective view which shows the elastic pressing means of the undercut molding block provided. 1 to 3, an injection molding apparatus 10 according to an embodiment of the present invention includes an upper disc 11, a lower disc 13, an upper core 15, and a lower core 20. . The upper disc 11 and the lower disc 13 are configured such that at least one of the two moves and approaches or moves away from each other. Normally, the lower disk 13 is fixed and the upper disk 11 is configured to be closer to or away from the lower disk 13. The upper disc 11 and the lower disc 13 may be in the form of a plate having a flat and constant thickness.

The upper core 15 is fixedly supported on the lower side of the upper disc 11, and the lower core 20 is supported on the upper side of the lower disc 13. When the upper disc 11 and the lower disc 13 are close to each other, the upper core 15 and the lower core 20 are in close contact with each other, and when the upper disc 11 and the lower disc 13 are far from each other, the upper core 15 ) And the lower core 20 are separated from each other. When the upper core 15 and the lower core 20 are in close contact with each other, a cavity 52 corresponding to the shape of the injection molded product 1 is formed.

The lower core 20 includes a fixed block 21 fixedly coupled to the lower disc 13, a first position closely contacted with the lower disc 13, and a Z-axis direction moved to be spaced apart from the lower disc 13. A movable block 30 movable between the two positions, and an undercut forming block 45 disposed between the fixed block 21 and the movable block 30 and elastically pressed to be in close contact with the fixed block 21. Equipped. In other words, the upper core 15 and the lower core 20 are brought into close contact with each other to form a cavity 52, and molten resin is injected and cured into the cavity 52 to move when the injection molded product 1 is formed. The position of the block 30 is in the first position, and the upper core 15 and the lower core 20 are separated from each other, and the injection molded product 1 molded in the cavity 52 is separated out from the lower core 20. When the position of the moving block 30 is the second position.

In the embodiment shown in the drawing, the product 1 formed by using the injection molding mold 10 has a rectangular frame shape as a bezel of a flat-panel TV or a flat-panel monitor, and has a rectangular frame shape in a horizontal direction from the edge of the rectangle to the inside. A protruding undercut 3 (see FIGS. 4-6). The fixing block 21 is fixedly arranged at the center of the lower disc 13. The upper side surface of the fixing block 21 is provided in the center portion and the first upper core contact surface 22 (see FIG. 5) which is in close contact with the upper core 15 at the time of injection of the cavity 52 of molten resin (not shown), It is divided into the first cavity defining surface 23 which is provided on the outer periphery of the first upper core contact surface 22 and corresponds to the lower surface of the product 1 and partially defines the cavity 52. The moving block 30 is arranged to surround its outer periphery outside the fixed block 21. The moving block 30 has first to fourth block pieces 31, 32, 33, and 34 joined to each other to form a rectangular closed curve, and the upper side thereof is injected with the cavity 52 of the molten resin. A second upper core contact surface 41 (see FIG. 5) in close contact with the upper core 15 is provided.

On the other hand, the injection molding die 10 is supported by the lower disc 13 and has a moving block actuator 70 for moving the moving block 30 between the first position and the second position. The moving block actuator 70 is connected to, for example, a pneumatic cylinder 71 fixed to the lower disc 13 and a rod 73 protruding or contracting from the pneumatic cylinder 71 and the other side of the moving block actuator 70. And a drive member 72 coupled to 30. The movement block 30 may move to the first position and the second position by the movement of the drive member 72.

The lower side surface of the upper core 15 facing the lower core 20 is provided in the center portion, and the first upper core contact surface 22 of the fixing block 21 at the time of injection of the cavity 52 of molten resin (not shown) ( It is provided in the outer periphery of the 1st lower core adhesion surface 18 (refer FIG. 5), and the 1st lower core adhesion surface 18 closely contacted with the upper surface of the product 1, and the cavity 52 comes in close contact with FIG. 2nd lower part which is provided in the outer periphery of the 3rd cavity limitation surface 17 which partially defines the (), and the 2nd upper core adhesion surface 41 of the moving block 30 in close contact. It is divided into the core contact surface 19 (refer FIG. 5).

The undercut forming block 45 is provided with an undercut groove 48 corresponding to the shape of the undercut 3 (see FIG. 4) of the product 1. When forming the product 1 by injection molding, the undercut groove 48 may be filled with a molten resin and cured to form the undercut 3. The undercut groove 48 is formed in a shape concavely recessed toward the fixing block 21 side. The upper side of the undercut forming block 45 is a second cavity defining surface 49 corresponding to the lower surface of the product 1 and partially defining the cavity 52. In summary, the cavity 52 corresponding to the shape of the injection-molded product 1 includes the first cavity defining surface 23 of the fixing block 21 and the second cavity defining surface 49 of the undercut forming block 45. ) And undercut grooves 48 and the third cavity defining surface 17 (see FIG. 5) of the upper core 15.

The side surface 25 of the fixing block 21 in close contact with the undercut forming block 45 is an inclined surface formed outside the first cavity defining surface 23. The inclined surface 25 of the fixing block 21 is inclined inclined with respect to the direction of the elastic pressing force applied to the undercut forming block 45, that is, the X-axis direction. With this configuration, when the moving block 30 moves from the first position (see FIG. 4) to the second position (see FIG. 6), the undercut forming block 45 moves in the inclined direction along the fixed block inclined surface 25. The undercut groove 48 is then spaced apart from the undercut 3 (see FIG. 6) of the injection molded article 1.

The side surface 46 of the undercut forming block 45 which is in close contact with the inclined surface 25 of the fixed block 21 is an inclined surface corresponding to the fixed block inclined surface 25, and the undercut forming block 5 is Assists easy slipping with respect to the fixed block slope 25. The side on which the undercut groove 48 is formed and the inclined surface 46 in close contact with the fixed block inclined surface 25 are disposed on the opposite side so as to lie against each other.

The means for elastically pressing the undercut forming block 45 in close contact with the fixed block 21 includes a rod 60, a spring 59, and a bracket 57. The rod 60 penetrates the moving block 30 in the horizontal direction, that is, in the X-axis direction, and one end 61 of the rod 60 is coupled to the undercut forming block 45. The spring 59 is inserted and seated in a spring seating groove 38 provided in the moving block 30 to elastically press the other end 62 of the rod 60 toward the fixing block 21. Bracket 57 is formed on the outer periphery of the moving block 30 is inserted into the bracket seating groove 37 connected to the spring seating groove 38 and fixed to the movable block 30 by a screw 55 spring ( 59).

The spring 59 is compressed between the bracket 57 and the other end 61 of the rod 60 and the play between the end of the spring seating groove 38 and the other end 61 of the rod 61. Since the undercut forming block 45 is elastically pressurized by the rod 60 to the inclined surface 25 side of the fixing block 21. The elastic pressing force is in the X-axis direction parallel to the longitudinal direction of the rod 60, which is the direction of movement of the moving block 30 moving between the first position (see FIG. 4) to the second position (see FIG. 6), That is, it is orthogonal to the Z axis direction. As shown in FIG. 6, when the moving block 30 moves from the first position to the second position, the injection molded article 1 is spaced apart from the stationary block.

4 to 6 are partial cross-sectional views sequentially illustrating a process in which the injection-molded product is separated out from the injection molding die of FIG. 1, and taken out after injection molding of the product 1 with reference to FIGS. 4 to 6. The process will be explained sequentially. Referring to FIG. 4, the moving block 30 is a first position in close contact with the lower disc 13 and is melted in the cavity 52 (see FIG. 1) formed by the upper core 15 and the lower core 20 in close contact. The resin 1 is injected and cured to form a product 1 with an undercut 3.

Referring to FIG. 5, the upper core 15 and the lower core 20 are spaced apart in order to separate and extract the product 1 from the injection molding mold 10 (see FIG. 1). The article 1 does not follow the upper core 15 but remains undercut 3 caught in the undercut groove 48 and attached to the lower core 20.

Referring to FIG. 6, the moving block 30 is moved to the second position. As the moving block 30 is spaced apart from the lower disc 13 and moves in the positive Z-axis direction, the undercut forming block 45 also moves in the same direction. Meanwhile, at the same time, the undercut forming block 45 is elastically pressurized to be in close contact with the fixed block inclined surface 25 by the rod 60, and thus the undercut forming block 45 is formed by the force of the force in the X-axis direction and the Z-axis direction. ) Moves along the fixed block inclined surface 25. As a result, the injection molded product 1 is moved in the direction of the Z axis positive (+) to be spaced apart from the fixing block 21, and the undercut 3 is separated from the obstruction by the undercut groove 48. As illustrated in FIG. 6, since the product 1 separated from the first cavity defining surface 23 of the fixing block 21 is exposed in a protruding state from the lower core 20, the worker easily makes a hand-made product ( 1) can be grabbed and taken out from the metal mold | die 10 (refer FIG. 1).

FIG. 7 is a cross-sectional view of an injection molding mold according to another embodiment of the present invention, and FIG. 8 is a perspective view illustrating the insert member of FIG. 7, which will be described below with reference to FIGS. 7 and 8. The injection molding die 10B which follows is demonstrated. Since this injection molding mold 10B is similar in many parts to the injection molding mold 10 shown in FIGS. 1-6, it demonstrates mainly about a structure with a difference. The same reference numerals as those shown in FIG. 1 among the reference numerals indicated in FIG. 7 denote the same members. Referring to FIG. 7, the upper core 15B and the lower core 20B of the injection molding mold 10B according to another embodiment of the present invention may be in close contact with each other and the molten resin may be injected into the cavity 52B. ) Is a thin plate shape in which the center part is closed, and an undercut 7 is formed in the outer peripheral part. To this end, even if the upper core 15B and the lower core 20B are in close contact with each other, the center portion of the fixing block 21B is finely spaced apart from the lower side of the upper core 15B to form a cavity space into which molten resin is to be injected. .

The injection molding apparatus 10B includes a take-out unit that separates and ejects the injection-molded product 5 from the lower core 20B when the upper core 15B and the lower core 20B are spaced apart from each other. The blowout unit has an air jet flow path extending from the outside of the lower disc 13 to the product 5 which is hardened by the resin through the lower core 20B, specifically, the fixing block 21B and attached to the lower core 20B. And an insertion member 140 inserted into the air jet flow path 160. The air jet flow path 160 may direct a high pressure air jet to the injection molded product 5. Although not shown in FIG. 7 for this purpose, the air jet passage 160 may be connected to an air jet pump provided outside the lower disc 13.

Even if the undercut forming block 45 is raised (see FIG. 6) so that the undercut 7 can be pulled out due to the characteristic of the product 5 in which the center part is closed, in part, for example, the center part of the product 5 is still fixed block ( 21B), a high-pressure air jet may be ejected to a portion of the product 5 to which it is stuck so that the entire product 5 may be separated from the lower core 20B. The worker can easily take out the product 5 thus separated entirely from the injection molding die 10B.

7 and 8, the insertion member 140 includes a body 150, a head 142, and a neck 144. The body 150 has an outer circumferential surface 151 which is in close contact with the inner circumferential surface of the air jet flow path 160, and is recessed in the concave toward the central portion of the outer circumferential surface 151 and extends in parallel with the extending direction of the air jet flow path 160. It has one groove 153. The head 142 is located closer to the cavity 52B than the body 150. The head 142 has a diameter that is not in close contact with the inner circumferential surface of the air jet flow path 160.

The interval G1 between the outer circumferential surface of the head 142 and the inner circumferential surface of the air jet flow path 160 is preferably 0.02 to 0.04 mm. This means that if the gap G1 is less than 0.02 mm, sufficient air is not supplied for the injection molded article 5 to be blown out, and if the gap G1 exceeds 0.02 mm, it enters the cavity 52B. This is because the molten resin may leak to the outside through the air jet flow path 160. Due to the minute gap G1, the molten resin does not flow out of the cavity 52B into the air jet flow path 160 even before it is cured.

The neck 144 connects the body 150 and the head 142. The neck 144 is smaller in diameter than the head 142. The distance between the neck 144 and the inner circumferential surface of the air jet flow path 160 is preferably 0.3 mm or more. The neck 144 serves as a tank for uniformly uniforming the air supplied through the air jet flow path 160, so that the injection molded product can be pushed up more uniformly. The depth G2 of the groove 153 may be 0.03 mm to 0.04 mm.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the present invention. Therefore, the true scope of protection of the present invention should be defined only by the appended claims.

3: undercut 10: injection molding mold
15: upper core 20: lower core
21: fixed block 25: fixed block slope
30: moving block 45: block for forming undercut
48: undercut groove 59: spring
60: rod 70: moving block actuator

Claims (9)

An upper plate and a lower plate, at least one of which moves toward and away from each other; And a cavity corresponding to the shape of an injection molded product having an undercut when formed in close contact with each other, the upper core being supported by the upper disc, and the lower core being supported by the lower disc. ,
The lower core may include a fixed block fixedly coupled to the lower disc; A movable block movable between a first position, which is a position when the upper core and the lower core are in close contact with each other, and a second position, which is a position when taking out the injection-molded product molded in the cavity from the lower core; And an undercut groove corresponding to the shape of the undercut, the undercut forming block being elastically pressed to be in close contact with the fixed block.
One side of the fixing block in close contact with the undercut forming block is an inclined surface inclined inclined with respect to the direction of the elastic pressing force applied to the undercut forming block,
When the moving block moves from the first position to the second position, the undercut forming block is moved in an inclined direction along the inclined surface of the fixed block such that the undercut groove is spaced apart from the undercut of the injection molded article. Injection molding mold. The method of claim 1,
The undercut forming block is an injection molding die, characterized in that the side on which the undercut groove is formed and the side in close contact with the fixing block are disposed on the opposite side. The method according to claim 1,
The moving block is disposed outside the fixed block, the undercut forming block is disposed between the fixed block and the moving block, the undercut groove is formed in a concave recessed shape toward the fixed block side Molding mold. The method of claim 3,
The moving block is formed to surround the outer periphery of the fixed block, injection molding mold, characterized in that it comprises a plurality of block pieces (block pieces) coupled to each other. The method according to claim 1,
And a direction in which the moving direction of the moving block and the direction of the elastic pressing force applied to the undercut forming block are orthogonal to each other. The method according to claim 1,
And the injection molded product is configured to be spaced apart from the fixed block when the moving block moves from the first position to the second position. The method according to claim 1,
The means for elastically pressurizing the undercut forming block to be in close contact with the fixed block includes a rod having one end coupled to the undercut forming block, and a rod inserted into the movable block so that the other end of the rod is inserted into the undercut forming block. An injection molding die, comprising: a spring for elastically pressing against the fixed block side. The method according to claim 1,
And a moving block actuator supported on the lower disc to move the moving block between the first position and the second position. The method of claim 1,
And a take-out unit for separating out the injection-molded product from the lower core when the upper core and the lower core are spaced apart from each other,
The blowout unit comprises: an air jet passage extending to the lower core to direct a high pressure air jet to the injection molded article; And
An outer circumferential surface inserted into the air jet flow passage, the outer circumferential surface in close contact with the inner circumferential surface of the air jet flow passage, and a groove which is recessed in a concave direction from the outer circumferential surface toward the center thereof and extends in parallel with an extension direction of the air jet flow passage; A body having a diameter that is closer to the cavity than the body and is not in close contact with the inner circumferential surface of the air jet flow path, and a neck connecting the body to the head and having a smaller diameter than the head ( an insertion member having a neck),
An injection molding mold, wherein an interval between an outer circumferential surface of the head and an inner circumferential surface of the air jet flow path is 0.02 to 0.04 mm.

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