JP2006272748A - Method of demolding molded article and mold assembly for injection molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify the draw of an insert from the undercut part of a molded article, to facilitate obtaining a mold at a low cost, and to improve the molding accuracy of the molded article and the productivity and yield of the product. <P>SOLUTION: At the time of the mold opening operation after the injection molding of the impeller 1, the drawing-out of the insert 226 from the mold is behorehand conducted, which insert 226 is for the shaft hole 2 of the impeller 1 which is a cut shape other than the undercut part of the impeller 1. Then by moving at a fixed speed the fixed side platen 223 and the movable side platen 244 to the direction for the two to separate relatively, the vector V1 of the separating direction is made to occur between the contact surfaces of the fixed side insert 225 and the movable side insert 247 and the V-shaped blade. By a component force generated by making a force corresponding to this vector V1 act on the V-shaped blade, the impeller 1 is turned to the circumferential direction, and by this the fixed side insert 225 and the movable side insert 247 are simultaneously drawn out from the blade grooves 3a, 3b that are the undercut parts of the impeller 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a method for punching a molded product having an undercut and an injection mold apparatus, and in particular, it is easy to detach the insert forming an undercut portion of a molded product, such as an impeller of a fuel pump, from the molded product. The present invention relates to a die-cutting method for a molded product and an injection mold apparatus using the same.

As shown in FIGS. 1 and 2, an impeller 1 of a fuel pump that supplies fuel to an engine is formed in a disk shape from a thermosetting resin such as a phenol resin, and a shaft hole 2 is formed in a central portion 1a thereof. Has been. A plurality of blade grooves 3a and 3b are formed on the front and back surfaces near the outer periphery of the impeller 1 over a range of 360 at regular intervals. As shown in FIG. 2, the blade grooves 3 a and 3 b are V-shaped blades which are inclined in both directions intersecting with an intermediate line PL (parting line: mold dividing surface) in the thickness direction of the impeller 1. Form a group.
Such a V-shaped blade group of the impeller 1 is caught on the dividing surface of the mold and forms a so-called undercut that does not come out of the mold. For this reason, it is not possible to perform die cutting only by moving the mold in the vertical direction with respect to the split surface as in a molded product without undercut.

This type of conventional impeller injection mold apparatus will be described with reference to FIG.
As shown in FIG. 3, the impeller injection mold apparatus includes a fixed mold 10 and a movable mold 11 (see, for example, Patent Document 1).
The stationary mold 10 includes a stationary mounting plate 10a, a runner stopper plate 10b, a stationary mold plate 10c, and a sprue bush 10d that introduces molten resin into the cavity C. A fixed side insert 10e is provided in the fixed side template 10c so as to be rotatable around an axis L through a bearing 10f. The fixed side insert 10e constitutes one half of the cavity C, and a projection that forms the blade groove 3a of the impeller 1 is provided on the surface facing the cavity C.

  The movable mold 11 includes a movable attachment plate 11a, a receiving plate 11c attached to the movable attachment plate 11a via a spacer block 11b, a movable mold plate 11d held on the receiving plate 11c, and an ejector. A pin 11e and an ejector plate 11f are provided. The movable side template 11d is provided with a movable side insert 11g so as to be rotatable around the axis L through a bearing 10h. The movable side nest 11g constitutes one half of the cavity C, and a projection that forms the blade groove 3b of the impeller 1 is provided on the surface facing the cavity C.

  In such an impeller injection mold apparatus, when taking out a molded product molded by injection of resin into the cavity C, that is, the impeller, the movable mold 11 is moved from the fixed mold 10 to the arrow X in FIG. Move in the direction to open the mold. As a result, the fixed-side template 10c is separated from the runner stopper plate 10b integrally with the movable-side mold 11 as shown in FIG. At this time, the cured runner portion R is separated from the impeller 1 in the cavity C and adheres to the runner stopper plate 10b side.

  If the mold opening is further continued from this state, the movable side mold plate 11d is separated from the fixed side mold plate 10c by releasing the parting lock (not shown) as shown in FIG. 4B. In this case, when the fixed side insert 10e of the fixed side template 10c tries to come out of the blade groove 3a of the impeller 1, a circumferential component force is applied to the fixed side insert 10e by the inclined surface of the blade groove 3a of the impeller 1. It acts and rotates the fixed side insert 10e in the direction of arrow A in FIG. As a result, the fixed side insert 10e of the fixed side template 10c completely comes out of the blade groove 3a of the impeller 1 and is separated from the impeller 1.

When the mold opening is continued, the runner portion R is detached from the runner stopper plate 10b as shown in FIG. When the movable side mold 11 moves in the direction of the arrow X in FIG. 4C and the movable side insert 11g of the movable side mold plate 11d tries to come out of the blade groove 3b of the impeller 1, the impeller 1 A circumferential component force acts on the movable side nest 11g by the inclined surface of the blade groove 3b, and the movable side nest 11g is rotated in the direction of arrow B in FIG. As a result, the movable side insert 11g of the movable side mold plate 11d is completely removed from the blade groove 3b of the impeller 1 and the mold release of the impeller 1 is completed.
JP 2004-66699 A

  However, in the conventional impeller injection mold apparatus as described above, the fixed side insert 10e and the movable side insert 11g that form the blade grooves 3a and 3b of the impeller 1 are respectively connected to the fixed side mold plate 10c and the movable side mold. Since the plate 11d needs to be rotatably provided, the fixed side mold 10 and the movable side mold 11 become complicated and expensive.

Further, in the conventional injection mold apparatus, in order to smoothly rotate the fixed side insert 10e and the movable side insert 11g, the outer peripheral surface of the fixed side insert 10e and the fixed side insert 10e are fitted to each other. It is relatively between the fitting hole inner peripheral surface of the template 10c, and between the outer peripheral surface of the movable side insert 11g and the fitting hole inner peripheral surface of the movable side template 11d to which the movable side insert 11g is fitted. A large gap is required. In this way, the misalignment is likely to occur between the fixed side insert 10e and the movable side insert 11g, and the misalignment remains between the fixed side insert 10e and the movable side insert 11g. In the case where the impeller is molded, a step corresponding to the misalignment occurs on the surface of the V-shaped blade, which makes it impossible to use as a product, resulting in a decrease in product yield.
Further, since the fixed side insert 10e and the movable side insert 11g are supported so as to be freely rotatable with respect to the fixed side mold plate 10c and the movable side template 11d, the fixed side insert 10e and the movable side insert 11g The phase in the circumferential direction is easily shifted and the phase alignment becomes troublesome. In addition, when the phases in the circumferential direction are shifted, a step is generated in the V-shaped blade, and as shown in FIG. A V-shaped blade group that intersects and inclines in both directions cannot be formed. That is, there has been a problem that the blade shape cannot be used for the impeller of the fuel pump.

  The present invention has been made to solve the above-described conventional problems, and can easily remove the insert from the undercut portion of the molded product and easily reduce the cost of the mold. It is an object of the present invention to provide a method for punching a molded product and an injection mold apparatus using the same, which can be realized in a simple manner and can improve the molding accuracy of the molded product, the productivity of the product, and the yield.

  In order to achieve the above object, the present invention provides a method for die-molding a molded product in an injection mold apparatus for molding a molded product having an undercut portion having a symmetrical shape with respect to a split surface, the split A fixed-side template integrally forming a fixed-side insert that forms one half of the undercut portion with the surface as a boundary, and the other half of the undercut portion with the dividing surface as a boundary A movable side mold plate integrally provided with a movable side insert, and the molded product can move with respect to the fixed side mold plate and the movable side mold plate during the mold opening operation of the injection mold apparatus. Thus, in addition to the undercut portion, other inserts that interfere with the movement of the molded product are performed in advance, and then the fixed mold plate and the movable mold plate are relatively separated from each other. At a constant speed during this relative separation The component force with respect to the vector in the separating direction generated in the fixed side insert and the movable side insert is applied to the undercut portion, and the molded product is moved in the direction of the component force to move the fixed side insert and the movable A side insert is pulled out from the undercut portion.

  An injection mold apparatus for molding a molded product having an undercut portion having a plane symmetry with a split surface between a fixed mold and a movable mold sandwiched between the fixed mold and the fixed mold. A fixed-side mold plate that forms a cavity of the molded product, and a fixed plate that is provided integrally with the fixed-side mold plate so as to face the cavity and forms one half of the undercut portion with the dividing surface as a boundary. The movable side mold has a side nest, and the movable side mold plate is formed integrally with the movable side mold plate so as to be opposed to the cavity. And having a movable side insert that forms the other half of the undercut portion, the molded product moves relative to the fixed side mold plate and the movable side mold plate when the mold is opened. To move the molded product in addition to the undercut A means for performing die-cutting of other inserts that cause obstacles in advance, and the fixed-side mold plate and the movable-side die plate in relation to the mold opening of the mold after die-cutting of the other inserts. The component is operated at a constant speed in the direction away from the outer side, and a component force with respect to the vector in the direction of separation generated in the stationary side insert and the movable side insert during the relative separation operation is applied to the undercut portion. Is moved in the direction of application of the component force, and the fixed side movable insert and the movable side insert are pulled out from the undercut portion.

  According to the method for punching a molded product and the injection mold apparatus according to the present invention, an undercut is performed so that the molded product can move with respect to the stationary mold plate and the movable mold plate during the mold opening operation. In addition to the part, other inserts that interfere with the movement of the molded product are removed in advance, and then the fixed side mold plate and the movable side mold plate are operated at a constant speed in the direction of relative separation. A component force with respect to the vector in the separation direction generated in the fixed side insert and the movable side insert during the relative separation operation is applied to the undercut portion, and the molded product is moved in the direction of the component force and the fixed side insert and Since the movable side insert is pulled out from the undercut part, it is easy to remove the insert from the undercut part of the molded product without adding a mechanism to move the fixed side insert or the movable side insert. Can be done and cost reduction of molds It can be easily realized. Moreover, since the fixed side insert and the movable side insert for undercut are integrated with each template, the forming accuracy of the undercut portion of the molded product is improved, and the yield of the product can be improved.

The features of the die-cutting method and the injection-molding die apparatus according to the present embodiment are such that the molded product can move relative to the fixed-side mold plate and the movable-side die plate during the mold opening operation. In addition to the cut part, other inserts that interfere with the movement of the molded product are performed in advance, and then the fixed side mold plate and the movable side mold plate are operated at a constant speed in a relatively separated direction, A component force with respect to the vector in the separation direction generated in the fixed side insert and the movable side insert during the relative separation operation is applied to the undercut portion, and the molded product is moved in the direction of the component force to fix the fixed side insert. And the movable side insert was pulled out from the undercut part.
With this configuration, it is possible to easily remove the insert from the undercut portion of the molded product and to easily realize cost reduction of the mold, as well as molding accuracy of the molded product, product productivity, and product Yield can be improved.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 5 is a cross-sectional view showing a part of an injection mold apparatus to which the method for die-molding a molded product according to the present invention is applied, and FIG. 6 is a plan view taken along line 6-6 in FIG. (A)-(C) is sectional drawing for operation | movement description of the injection molding die apparatus in a present Example.

In FIG. 1, the impeller injection mold apparatus 20 includes a fixed mold 22 and a movable mold 24.
The fixed side mold 22 includes a fixed side mounting plate 221, a runner stopper plate 222, a fixed side mold plate 223, and a sprue bushing 224 that introduces molten resin into the cavity C. The cavity C of the injection mold apparatus 20 in this embodiment is a four-cavity with four.

The fixed side mold plate 223 forms a cavity C of the impeller 1 (see FIG. 1) as a molded product on the dividing surface of the mold, and the fixed side insert 225 is integrally formed with the fixed side mold plate 223. Is provided. The fixed side insert 225 constitutes one half of the cavity C, and a surface facing the cavity C is provided with a protrusion 225a (see FIG. 8) that forms a blade groove 3a (see FIG. 1) of the impeller 1. .
Further, the fixed side template 223 penetrates in the thickness direction and penetrates the shaft center of the fixed side insert 225 and protrudes into the cavity C to form the shaft hole 2 (see FIG. 1) of the impeller 1. A rod-like insert 226 (this is a D-cut insert and corresponds to the other insert described in the claims) is slidably provided. The upper end of the insert 226 is connected to the runner stopper plate 222.

The movable side mold 24 includes a movable side mounting plate 241, a receiving plate 243 attached to the movable side mounting plate 241 via a spacer block 242, a movable side mold plate 244 held by the receiving plate 243, and an ejector. A pin 245 and an ejector plate 246 are provided.
The movable side mold plate 244 forms a cavity C of the impeller 1 (see FIG. 1) which is a molded product on the dividing surface of the mold. The movable side mold plate 244 is integrally formed with a movable side insert 247. Is provided. The movable side insert 247 constitutes one half of the cavity C, and a projecting portion 247a (see FIG. 8) for forming the blade groove 3b (see FIG. 1) of the impeller 1 is provided on the surface facing the cavity C. .

As shown in FIGS. 5 and 6, the injection mold apparatus 20 includes a runner stopper plate 222, a fixed side mold plate 223, and a movable side mold plate 244 at the four corners of the fixed side mounting plate 221. In addition, guide pins 26 that pass through the receiving plate 243 and project inside the spacer block 242 are provided. The guide pin 26 guides the fixed side mold plate 223 and the movable side mold plate 244 so as to be movable toward and away from each other. In FIG. 5, reference numeral 28 denotes a return pin of the ejector plate 246.
The surface roughness of the mold for molding the impeller 1 is, for example, Rmax 5 μm.

Next, the operation of such an injection mold apparatus 20 will be described.
First, as shown in FIG. 5, the molten resin material supplied from an injection mechanism (not shown) is inserted into a sprue bushing 224 and a mold clamping state in which the divided surfaces of the fixed side mold plate 223 and the movable side mold plate 244 are aligned with each other. The cavity C is injected and filled at high pressure through a sprue, gate, etc. (not shown). At this time, the fixed side mold 22 and the movable side mold 24 are heated to a temperature of about 150 ° C. by a built-in heater (not shown).

  Next, the case where the impeller 1 molded by injection and filling of the resin into the cavity C is taken out will be described. In this case, the movable mold 24 is moved with respect to the fixed mold 22 in the direction of the arrow X in FIG. As a result, the fixed-side template 223 is separated from the runner stopper plate 222 integrally with the movable-side template 244 as shown in FIG. At this time, the cured runner portion R is separated from the impeller 1 in the cavity C and adheres to the runner stopper plate 222 side. Further, when the stationary side mold plate 223 is separated from the runner stopper plate 222, the insert 226 is die-cut from the shaft hole 2 of the impeller 1. Thereby, die cutting with a cut shape other than the undercut portion forming the V-shaped blades of the impeller 1 can be performed in advance so that the impeller 1 can be rotated in the circumferential direction with respect to the fixed mold plate 223 and the movable mold plate 244. Will be done.

  After the insert 226 is removed from the mold, the mold opening operation is continued at a constant speed, for example, 10 mm / sec. Then, as shown in FIG. 7B, the movable side mold 24 including the movable side mold plate 244 is moved in the direction of the arrow X at a constant speed (10 mm / sec) and at the same time movable with the fixed side mold plate 223. The side mold plate 244 is relatively separated. Along with this, when the movable side template 244 is pulled in the direction of the arrow X, the protrusion 225a of the fixed side insert 225 and the protrusion 247a of the movable side insert 247 are sandwiched across the parting line PL shown in FIG. The vector V1 in the mold opening direction as shown in FIG. 8 acts on the contact surface with the V-shaped blade 1A facing this. When this vector V1 acts on the V-shaped blade 1A, the vector in the direction D (direction of arrow D shown in FIG. 7C) in which the impeller 1 is rotated according to the vector V1 and the inclination angle θ. V2 is generated. The combined vector V3 of the vectors V1 and V2 is a vector in a direction in which the impeller 1 is removed from the fixed side insert 225 and the movable side insert 247. Thus, as the parting line PL between the fixed side mold plate 223 and the movable side mold plate 244 is relatively separated, the impeller 1 is rotated in the direction of the arrow D shown in FIGS. 7C and 8. . Accordingly, as shown in FIG. 7C, the fixed side insert 225 and the movable side insert 247 are simultaneously removed from the undercut portions of the impeller 1, that is, the blade grooves 3a and 3b. Complete. Then, the impeller 1 is shape | molded sequentially by repeating the operation | movement mentioned above.

  In FIG. 8, the inclination angle θ of the blade 4 forming the undercut portion of the impeller 1 is not limited to 45 degrees, and the surface side of the impeller 1 (the blade groove 3 a side) centering on the dividing surface PL of the mold. If the back surface side (blade groove 3b side) has the same inclination angle θ, the nested die can be removed from the undercut portion within the range of 90 °> θ ≧ 45 °.

  According to the injection mold apparatus 20 of the present embodiment as described above, the impeller 1 is moved to the fixed side mold plate 223 and the movable side mold plate 244 during the mold opening operation of the mold after the injection molding of the impeller 1 which is a molded product. The insert 226 is cut in advance from the shaft hole 2 of the impeller 1 having a cut shape other than the undercut portion of the impeller 1 so as to be able to rotate in the circumferential direction with respect to the fixed side template 223. By operating the movable side mold plate 244 at a constant speed in a direction relatively away from each other, the fixed side insert 225, the movable side insert 247, and the contact surface of the V-shaped blade 1A can be moved in the mold opening direction. When the vector V1 acts, the impeller 1 is rotated in the circumferential direction by the vector V1 and the vector V2 generated in accordance with the inclination angle θ, and the fixed side insert 225 and the movable side insert 247 are moved to the impeller 1. Since the blade grooves 3a and 3b, which are the lower cut portions, are simultaneously removed, the fixed side insert 225 and the movable side insert 247 can be easily and quickly removed from the undercut portion of the impeller 1. In addition, since a special die-cutting mechanism for rotatably supporting the fixed side insert and the movable side insert as in the prior art becomes unnecessary, the cost reduction of the mold can be easily realized.

  In addition, according to the present embodiment, the fixed side insert 225 and the movable insert 247 for undercut are integrated with each template, and therefore the phase in the core circumferential direction between them is shifted. There is an effect that the impeller molding accuracy can be improved and the productivity of the product and the yield of the product can be improved.

In the above-described embodiments, the method for die-molding a molded product and the injection mold apparatus according to the present invention are applied to an impeller used for a fuel pump. The present invention can also be applied to molding of a molded product having an undercut portion having a symmetrical shape with respect to the surface.
The present invention is not limited to the above-described embodiment, and can be implemented in various other forms without departing from the gist described in the claims.

It is a top view of the impeller used for a fuel pump. It is a side view which expands and shows a part of impeller. It is sectional drawing which notches and shows a part of conventional injection molding die apparatus. (A) thru | or (C) is sectional drawing for operation | movement description of the conventional injection molding die apparatus. It is sectional drawing which notches and shows a part of injection molding die apparatus concerning this invention. FIG. 6 is a plan view taken along line 6-6 of FIG. (A) thru | or (C) is sectional drawing for operation | movement description of the injection molding die apparatus in a present Example. It is explanatory drawing which shows the relationship between the impeller blade | wing in this Example, a fixed side nest | insert, and a movable side nest | insert.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Impeller 2 Shaft hole 3a, 3b Blade groove 4 Blade 20 Injection mold apparatus 22 Fixed side die 221 Fixed side mounting plate 222 Runner stopper plate 223 Fixed side template 224 Sprue bushing 225 Fixed side insert 24 Movable side template 241 Movable side mounting plate 242 Spacer block 243 Receiver plate 244 Movable side mold plate 245 Ejector pin 246 Ejector plate 247 Movable side insert 26 Guide pin 28 Return pin C Cavity

Claims (4)

A method of punching a molded product in an injection mold apparatus for molding a molded product having an undercut portion having a symmetrical shape with respect to a divided surface,
A fixed-side template integrally forming a fixed-side insert that forms one half of the undercut portion with the dividing surface as a boundary; and the other half of the undercut portion with the dividing surface as a boundary A movable side mold plate integrally provided with a movable side nesting to form,
Other than the undercut portion, the movement of the molded product is hindered so that the molded product can move relative to the fixed mold plate and the movable mold plate during the mold opening operation of the injection mold apparatus. The nesting of the insert is performed in advance, and then the fixed side mold plate and the movable side mold plate are operated at a constant speed in a direction in which the fixed side mold plate and the movable side mold plate are relatively separated from each other. A component force with respect to a vector in a separating direction generated in the child and the movable side insert is applied to the undercut portion, and the molded product is moved in the direction of the component force to move the fixed side insert and the movable side insert. A method for die-molding a molded product, wherein the die-cutting is performed from the undercut portion.   The molded product is an impeller of a fuel pump, and the undercut portion is a blade groove that forms a V-shaped blade that is bi-directionally inclined by intersecting with a dividing surface that is the center in the thickness direction of the impeller, The other insert is for the shaft hole of the impeller, and the moving direction of the impeller is a direction in which the impeller rotates around the axis of the fixed side insert and the movable side insert. A method for die-molding a molded product according to 1. An injection mold apparatus for molding a molded product having an undercut portion having a symmetrical shape with respect to a split surface between a fixed side mold and a movable side mold,
The fixed-side mold includes a fixed-side mold plate that forms a cavity of the molded product on a divided surface, and the undercut that is provided integrally with the fixed-side mold plate so as to face the cavity. Having a fixed side nest that forms one half of the part,
The movable side mold includes a movable side mold plate that forms a cavity of the molded product on a divided surface, and the undercut that is provided integrally with the movable side mold plate so as to face the cavity. A movable side nest that forms the other half of the part,
Other nesting molds other than the undercut portion that interfere with the movement of the molded product so that the molded product can move relative to the fixed-side mold plate and the movable-side mold plate when the mold is opened. Means for performing punching in advance, and at a constant speed in a direction in which the fixed mold plate and the movable mold plate are relatively separated in conjunction with mold opening of the mold after the other inserts are punched. The component is operated on the undercut portion with respect to the vector in the separation direction generated in the fixed side insert and the movable side insert during the relative separation operation, and the molded article is moved in the component force application direction. An injection mold apparatus characterized in that the fixed side insert and the movable side insert are pulled out from the undercut portion.   The molded product is an impeller of a fuel pump, and the undercut portion is a blade groove that forms a V-shaped blade that is bi-directionally inclined by intersecting with a dividing surface that is the center in the thickness direction of the impeller, The other insert is for the shaft hole of the impeller, and the moving direction of the impeller is a direction in which the impeller rotates around the axis of the fixed side insert and the movable side insert. 3. An injection mold apparatus according to 3.