JP2520666B2 - Injection mold - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die used for injection molding of plastic, and more particularly to a structure of a slide core forming an undercut portion.

(Prior Art and its Problems) Conventionally, as a method of molding or processing with plastic, there is so-called injection molding in which plastic plasticized by heating is injected into a mold at a high pressure and then cooled and solidified for molding.

Although there are various types of molds used for this injection molding, they are usually divided into two parts, a fixed side and a movable side.

Then, the mold is attached to each of the fixed-side die plate and the movable-side die plate of the injection molding machine, and molding is performed by each process of mold clamping, injection of molding material, pressure holding, cooling, mold opening, and ejection of molded product. It is a thing.

In such an injection mold, the shape of the molded product,
When there is a so-called undercut part that becomes a catch in the opening and closing direction of the mold when releasing the mold, this undercut part is configured with a slide core that is a separate component, and is opened and closed each time the mold is opened and closed. It must be moved so that it does not interfere with product removal.

Mold structure using slide core is generally complicated,
Not only is it expensive, but it also causes failures during molding, so it is desirable to have a product design without undercut if possible. However, in recent years, more complicated molded products have been molded using slide cores.

As such a method of moving the slide core, an angular pin inclined to the mold opening direction in the moving direction of the slide core is fixed to the fixed side, and the slide core is slidably fitted to the angular pin. However, the slide core is configured to slide in a direction perpendicular to the mold opening direction when the mold is opened (moving on the movable side), or the ejector plate and the slide core are arranged as disclosed in Japanese Utility Model Laid-Open No. 62-13619. For example, the slide core may be moved at the same time as the molded product is projected from the mold by connecting them.

However, in the case where the undercut portion is formed using the slide core as described above, particularly in the case where the shape of the molded product has a bag-shaped corner portion, the sliding direction of the slide core is It may be restricted by the part that is undercut in the sliding direction. On this occasion,
When using multiple slide cores adjacent to each other,
In some cases, the slide directions of the adjacent slide cores interfere with each other, so that the die core structure cannot be formed.

For example, when the product having the shape shown in FIG. 8 is used as the parting line (abbreviated as PL) shown in FIG. 9 and the undercut portion is formed by using a plurality of slide cores A, B and C as shown in FIG. Considering this, the slide directions A ′ and C ′ of the slide cores A and C interfere with the slide core B and the slide direction B ′, so that they cannot be configured.

In such a case, change the design and change the product shape to deal with it, or if the shape cannot be changed, use a mounting piece that is manually attached and detached by the operator at the corner where the slide core cannot be used. ing. However, the molding using the placing piece has not only poor workability and low productivity, but also a problem that the work is dangerous.

(Object of the Invention) In view of the above situation, an object of the present invention is to provide an injection molding die capable of molding a bag-shaped corner portion without using a placing piece.

(Structure of the Invention) An undercut portion is formed by a plurality of slide cores that slide along with product protrusion, and an inclined core that slides in a direction that interferes with an adjacent slide core, and the adjacent slide cores. A space having a width equal to or larger than the interference amount due to the movement of the inclined core is formed between the and, and the space portion is formed by a moving piece capable of retracting and moving an undercut portion in the space. A drive means for moving and moving the piece is provided to avoid interference during sliding between the moving core and the adjacent slide core, and the moving piece is moved and driven by the driving means to take out a molded product. A mold for injection molding characterized by the fact that it is possible.

With this configuration, it is possible to avoid the interference between the moving core and the adjacent slide core, enable the moving core and the adjacent slide core to slide, and move the moving piece by the driving means. The movable piece is retracted from the undercut portion in the space so that the molded product can be taken out.

(Embodiment of the Invention) Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a front fender 10 of an automobile molded by the injection molding die of this embodiment, and the parting line (PL) is located at the position shown in FIG. 2 which is a II-II sectional view of FIG. Then, the X part in the figure becomes an undercut,
The corner portion indicated by Z in FIG. 1 has a bag structure.

FIG. 3 is a plan view of the movable side mold 1, FIGS. 4 and 6 are IV-IV sectional views and VI-VI sectional views of FIG. 3, and FIG. 5 is V of FIG. Each of the -V cross-sectional views is shown.

The overall mold structure is configured such that the fixed mold 2 (not shown in FIG. 3) is the cavity side, the movable mold 1 is the core side, and the ejector plate 3 is provided on the movable side. It is a thing.

In the movable mold 1, the undercut portion (that is, the upper edge portion of the front fender 10) has an inclined core 11 and a slide core.
It is configured to be formed by using 12 and 13.

The upper ends of the angular shafts 31, 32, and 33 are fitted and fixed to the inclined core 11 and the slide cores 12 and 13, respectively.
The angular shafts 31, 32, 33 are slidably fitted in fitting holes 1C formed in the movable side mold 1 as shown in the fifth and seventh drawings, respectively, and the opening portion of the ejector plate 3 is formed. A sliding piece 3B penetrating 3C and fixed to the lower end thereof is slidably fitted and connected to a slide guide 3A fixed to the back surface of the ejector plate 3.

The fitting hole 1C of the movable mold 1 through which the angular shafts 31, 32, 33 fit can be released by sliding (sliding) the inclined core 11 and the slide cores 12 and 13 from the undercut when the mold is opened. In this way, the sliding pieces 3B are respectively formed so as to be tilted in a predetermined direction at a predetermined angle, and the sliding direction of the sliding piece 3B is also the same direction (that is, the sliding direction of the inclined core 11 and the slide cores 12 and 13. Details will be described later. ) Is configured.

Then, at the end of the mold opening stalk of the movable side mold 1, the ejector plate 3 is relatively moved to the movable side mold 1 side to be guided by the fitting hole 1C of the movable side mold 1 and the angular shaft 31. 32 and 33 move, slide the inclined core 11 and the slide cores 12 and 13 in a predetermined direction to escape from the undercut, and push up the molded product (front fender 10) from the mold surface of the movable side mold 1 to separate it. It acts as a mold. The tilt core 11 and the slide core 12
The divided surface (matching surface) with 13 is formed following the three-dimensional moving direction of the inclined core 11 and the slide cores 12 and 13 by the ejector plate 3, and is configured to abut and slide on the surface. It has been done.

The sliding direction of the slide cores 12 and 13 is the vertical direction in FIG. 2 and is substantially perpendicular to the undercut component of the molded product (the upper surface 10B of the front fender 10), but the inclination If the sliding direction of the core 11 is slid in the same direction as the slide cores 12 and 13, the front end surface 10A of the front fender 10 is undercut with respect to the sliding direction. It is configured to slide in the direction of the center line that bisects the intersection angle with 1A.

As a result, if the slant core 11 and the slide core 12 are configured to contact each other without a gap, the sliding directions will interfere. However, in order to prevent the interference and enable the slidable core 11 and the slide core 12 to slide. A gap having a predetermined width, which is wider than the amount of interference due to the sliding of the two, is provided between the members 12, and a movable piece 14 is fitted and inserted in this gap portion. That is, the movable piece 14 is inserted into the concave portion formed by the adjacent side surfaces of the inclined core 11 and the slide core 12 and the upper surface of the movable mold 1.

The side surfaces that form the recesses are parallel to the three-dimensional moving directions of the slid core 12 side and the slant core 11 side, respectively. Further, the portion of the movable die 1 that forms the bottom surface of the recess is a groove 1E having a predetermined depth.

The longitudinal direction of the concave portion is defined by the inclined core 11 and the slide core.
Movable mold 1 with an extended side surface formed by 12
A wall surface 1D is formed by entering a predetermined amount inside, and the wall surface 1D on the movable side mold 1 side is a vertical surface with respect to the movable side mold 1. An embedded metal 16 is fastened and fixed to the upper side of the movable mold 1 which is the end of the recess, and the embedded metal 16 projects toward the undercut side within a range that does not interfere with the undercut portion in the recess. It forms the 16A.

The movable piece 14 forms the mold surface 14D of the above-mentioned recessed portion, fits slidably with the side surface of the recessed portion formed by the inclined core 11 and the slide core 12 without a gap, and the movable side mold 1
Is in slidable contact with the upper surface (groove 1E) of the movable metal mold 1 through the slide metal 1F, and the end 14E on the movable mold 1 side and the wall surface 1D of the recess of the movable mold 1 have a predetermined shape. It is formed with a space S. That is, the moving piece 14 is movable within the distance S, and this distance S is the moving piece 14 concerned.
The distance is such that the undercut portion formed by the mold surface can be retracted.

Further, the movable piece 14 has an extension portion 14A formed by extending the contact surface side (lower surface side) with the movable mold 1 to the edge side of the movable mold 1 with a predetermined thickness. The extension 14A is connected to the spindle 4A of the hydraulic cylinder 4 fixed to the side end of the movable mold 1, and the moving piece 14 is driven to move by the hydraulic cylinder 4. .

Further, the extension portion 14A of the moving piece 14 has a rectangular positioning hole 1
4B is formed. The wall surface on the side edge side of the positioning hole 14B is formed with a taper surface 14C in a direction in which the lower side is narrowed. By abutting, the moving piece 14 is configured to be pressed and urged to a prescribed position for positioning.

Extension 14A of moving piece 14 and molded product (front fender 1
Between the undercut forming portions of 0), a lower mold surface 15B of the undercut portion of the molded product is formed on the upper surface, and a groove 15A slidably fitted to the extended portion 14A is formed on the lower surface. The guide plate 15 is fixed to the movable mold 1 by fitting the groove 14D with the extending portion 14A.

Thus, in the radiation molding die configured as described above, the fixed-side die 2 and the movable-side die 1 are clamped at a predetermined pressure when the die is clamped, and the ejector plate 3 is moved to the movable-side die. It is urged in a direction away from the mold 1. As a result, the taper 2B surface of the lock block 2A of the fixed side mold 2 is controlled with the taper surface 14C of the positioning hole 14B of the moving piece 14, and the moving piece 14 is biased and positioned in the side edge side direction, and the inclined core 11 and slide cores 12 and 13 are also biased and positioned by the movable mold 1.

After that, when the injection / holding pressure of the molding material and the cooling process are completed, the mold is opened and the molded product is taken out. At the time of opening the mold after the completion of molding, the molded product is taken out by the following actions.

First, the movable mold 1 is moved and driven to open the joint (PL) with the fixed mold 2.

When the distance between them becomes a predetermined distance, the hydraulic cylinder is driven to move and move the moving piece 14 to retract (release) from the undercut portion.

Then, the ejector plate 3 is driven to move to the movable mold 1 side, and the inclined core 11 and the slide cores 12 and 13 are driven to move away from the undercut and away from the movable mold 1.

As a result, the molded product (front fender 10) has its undercut portion removed from the inclined core 11 and the slide cores 12 and 13, and is ejected from the movable mold 1 and released from the mold.

That is, it is possible to form a bag-shaped corner portion which could not be formed by the conventional slide core alone due to the interference of the sliding direction of the slide core.

In the present embodiment, although not shown or described, an ejector pin connected to the ejector plate 3 is provided at a predetermined position, and the inclined core 11 and the slide core 12 are provided.
It goes without saying that the ejector pin is configured to project and release the molded product when the molded product is projected by 13.

(Effects of the Invention) As described above, according to the injection molding die of the present invention,
Even if the slide directions of the adjacent slide cores interfere with each other, the slide cores can be molded without changing the design of the molded product or using a mounting piece. That is, the restriction of the shape in the design of the molded product is reduced, the productivity is improved, and the molding work can be performed with good workability and safety.

[Brief description of drawings]

FIG. 1 is a perspective view of a front fender of an automobile molded by an embodiment of an injection molding die according to the present invention.
1 is a sectional view taken along the line II-II in FIG. 1, FIG. 3 is a plan view of the movable mold 1, FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3, and FIG. 5 is line V-V in FIG. Sectional view, FIG. 6 is a sectional view taken along line VI-VI of FIG. 3, and FIG.
6 is a sectional view taken along the line XII-XII in FIG. 6, FIG. 8 is a perspective view of a molded product showing the conventional problems, and FIG. 9 is a sectional view taken along the line IX-IX in FIG.
FIG. 10 is an explanatory diagram showing conventional problems. 1 …… Movable side mold 4 …… Hydraulic cylinder (driving means) 10 …… Front fender (molded product) 11 …… Inclined core 12 …… Slide core (adjacent slide core) 14 …… Movement piece X …… Under Cut part

Claims (1)

(57) [Claims] 1. An undercut portion is formed by a plurality of slide cores that slide along with the protrusion of a product, and an inclined core that slides in a direction that interferes with adjacent slide cores, and the adjacent slide cores. A space having a width equal to or larger than the interference amount due to the movement of the inclined core is formed between the and, and the space portion is formed by a moving piece capable of retracting and moving an undercut portion in the space. A drive means for moving and moving the piece is provided to avoid interference during sliding between the moving core and the adjacent slide core, and the moving piece is moved and driven by the driving means to take out a molded product. A mold for injection molding characterized by the fact that it is possible.