JPH049152Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement in an injection mold used for injection molding of a product having an undercut portion.

[Conventional technology]

Complicated shapes such as automobile parts are made by injection molding. These parts include undercuts, such as bosses. When injection molding a product having such an undercut portion, special considerations are required to ensure that the product can be demolded reliably.

Generally, an injection mold is divided into several parts for easy demolding, and a slide core is used for the undercut part.

A conventional injection mold will be explained with reference to FIGS. 5 and 6. The mold shown in FIG. 5 is for making a product 9 having a boss part b (undercut part), and a slide core 3 for molding this boss part b is slidably provided in the movable mold 1. .

In this mold, by moving the movable mold 1 in the direction of arrow A, the slide core 3 is pulled out in the direction of arrow B by engaging with the hook-shaped groove C provided in the slide core guide block 16. Remove from the boss part b. Further, when the mold is closed, the slide core 3 is inserted and positioned along the groove of the slide core guide block 16.

In this manner, the slide core guide block 16 is provided for positioning the slide core 3 during mold removal and mold closing.

In the figure, reference numeral 8 denotes a stopper, and during demolding, the slide core 3 is pressed against the stopper 8 and held by the elastic force of the spring 7.

The mold shown in FIG. 6 uses two core pullers. That is, in order to make a product having the same shape as shown in FIG. 5, an opening c is provided in the product 9.
The boss part b is formed by a core puller slide block 17 that slides inside the fixed mold 2, while the seating surface of the boss part b is formed by a slide block 17 that slides inside the movable mold 1 using a coil spring 13 and a core puller slide pin 12. It is designed to be formed by a core 11. 8 is
This is a stopper attached to the movable mold 1.

[Problem that the invention attempts to solve]

Among the conventional molds described above, the one shown in FIG. 5 has the following problems. That is, when the movable mold 1 is opened in the direction of arrow A, the tensile force (floating force) of the slide block 3 acts on the slide core guide block 16 in a direction perpendicular to the mold opening direction, so that the slide core Guide block 16
It is necessary to fix it to the fixed mold 2.

However, since the mounting position of the slide core guide block 16 to the fixed mold 2 is where the fixed mold 2 is U-shaped, the fixing bolt 14
The machine tool for drilling the screw holes for screwing the parts cannot be set in that part. In order to solve this problem, the fixed mold 2 is divided to provide a partial insert 18, and a pocket hole 15 and a screw hole for fitting the slide core guide block 16 into the partial insert 18 are machined to form the slide core. Guide block 1
6 is fixed to a partial insert 18, and this partial insert 18 is further fixed to the fixed mold 2 with a bolt 14.

In a mold having such a structure, the fixed mold 2 is divided into two parts in order to provide the partial insert 18, so its strength is reduced, and the joint a between the partial insert 18 and the fixed mold 2 is
There was a problem in that gaps were generated and burrs were generated in that part, and mold cracks were generated in the bottom corner a' of the insert hole in which the partial insert 18 was embedded.

Furthermore, the mold shown in FIG. 6 has the following problems. That is, an opening c is opened in the product 9, and a mounting boss b is opened in the product 9.
(Undercut) Since two core pullers are required for each location, the structure of the mold itself becomes complicated, and there are drawbacks such as occurrence of burrs and problems in terms of strength.

Further, the slide core 11, which is slidably held by the movable mold 1, is moved in the direction of arrow C only by the coil spring 13, and movement in the opposite direction is achieved by sliding it into the fixed mold 2. Since this is performed by a movably provided core puller slide pin 12, the coil spring 13 has a slide core 11.
A function is required to ensure that the movement returns in the direction of arrow C. For example, if the coil spring 13 is damaged,
Alternatively, if galling or the like occurs between the movable mold 1 and the slide core 11 and the slide core 11 no longer moves in the direction of the arrow C, when pushing out the product 9 after opening the mold, the boss part There was a problem in that cracks could occur in b.

In addition, when using this mold, it is necessary to provide an opening c in the product 9, so this mold can only be applied to instrument panel inserts, etc., and is not suitable for parts that are visible to the public as a design. There was a problem in that the scope of application of molded parts was limited.

Furthermore, in instrument panel inserts and the like, there is a problem in that extra man-hours are required to cover the openings with tape or the like in order to prevent foamed material such as skin foaming from flowing out from the openings c.

The present invention aims to provide an injection molding mold having an undercut treatment structure that solves all of the above-mentioned problems and drawbacks.

[Means to solve the problem]

In order to solve the above problem, the present invention provides a movable type with a slidable slide core, and a fixed type with a core puller slide pin that is slidable in the sliding direction of the slide core. This is characterized in that the end of the puller slide pin is provided with a connecting portion that can be inserted and removed in the moving direction of the movable mold.

[Effect]

With the above configuration, the slide core is reliably slid by the core puller slide pin, and when the mold is opened, the slide core and the core puller slide pin are disconnected, and the slide core is moved into the movable type. The mold is opened with

〔Example〕

An embodiment of the present invention will be described in detail below.

The same parts in FIG. 5 and FIG. 6 are designated by the same reference numerals. In FIG. 1, 1 is a movable type and 2 is a fixed type. A slide core 3 is slidably provided in the movable mold 1. On the other hand, the fixed mold 2 is provided with a core puller slide pin 4 so as to be slidable in the sliding direction of the slide core 3. 6 is a guide bush, 5 is a cylinder attached to the fixed mold 2 with bolts 10, and the core puller slide pin 4 is moved by the cylinder 5 in the two directions of the arrows while being guided by the guide bush 6. There is. The slide core 3 and core puller slide pin 4 are detachably connected in the mold opening or mold closing direction (arrow A direction) of the movable mold 1. This connection is
As shown in FIG. 2, the flange 3a provided on the slide core 3 and the flange 4a provided at the tip of the core puller slide pin 4 fit together, and the movement of the core puller slide pin 4 is caused by the slide core 3. As well as being conveyed, at the time of mold opening (or mold closing),
This connection is now being released. 〓d ₃
and _d4 are provided to facilitate attachment and detachment of the slide core 3 and core puller slide pin 4. Reference numeral 7 denotes a spring whose elastic force is biased to push the slide core 3 in the direction of arrow C, and when the mold is opened, the elastic force of the spring 7 presses the slide core 3 in the direction of arrow C. A slide core 3 is supported in a pressed state against a stopper 8 provided on a movable mold 1. In addition, by supporting the slide core 3 in this way, the distance between d ₁ and d ₂ shown in FIG. Established
d ₅ and d ₆ shown in Fig. 4 (positioning necessary for contact between the lower part of the slide core 3 and the fixed mold 2 and fitting of the flanges 3a and 4b when opening or closing the mold). It is supported by Also, the tip 4b of the core puller slide pin 4 and the lower surface 3 of the slide core 3
b are planes formed in a direction perpendicular to the sliding direction, and these planes 3b and 4b are in contact with each other to prevent force from escaping in any direction other than the sliding direction, and the resin pressure during raw material injection is reduced. The structure is designed to ensure that the

The operation of this embodiment configured as above will be explained next.

In FIG. 1, a product 9 having a boss portion b is injection molded by the tip of the slide core 3.
In this injection molding, since the fixed mold 2 and the movable mold 1 have no divided parts, they have sufficient strength against the injection pressure during raw material injection and do not generate burrs. Moreover, the slide core 3 has surfaces 4b, 3b.
It is firmly held by the core puller slide pin 4 in the sliding direction, and is reliably held against injection pressure.

Next, after the molding is completed, the movable mold 1 is moved in the direction of arrow A to open the mold. When opening this mold, first, the third
As shown in the figure, the core puller slide pin 4 is slid downward, and the slide core 3 is slid in the direction of arrow C until it abuts against the stopper 8, and the tip of the slide core 3 is removed from the boss portion b. and,
By cylinder 5, core puller slide pin 4
Stop and hold at this position.

Next, as shown in FIG. 4, the movable mold 1 is pulled out in the direction of the arrow to open the mold. In this state, the slide core 3 is held at a predetermined position by the spring 7 and the stopper 8, and is pulled out together with the movable mold 1. Also, when opening the mold, since there are gaps d ₅ and d ₆ , no galling occurs between them, and the mold can be opened smoothly.

After opening the mold, the product 9 is extruded by an ejector pin (not shown), completing one cycle. During this extrusion, there is no contact between the slide core 3 and the boss part b due to the gap _d2 including the gap _d1 , and therefore no cracks or the like occur in the boss part b.

Next, when extruding the product 9 and closing the mold, the movable mold 1 is directly pushed toward the fixed mold 2 side.
At this time, the core puller slide pin 4 is held at its original position, so the flanges 3b and 4b fit into each other, and the slide core 3 and the core puller slide pin 4 are connected. The cylinder 5 is then actuated with a constant stroke to push up the core puller slide pin 4 to hold the slide core 3 in place and the next cycle begins.

〔effect〕

As detailed above, according to the injection mold having the undercut treatment structure according to the present invention, the movable mold is provided with a slidable slide core, and the slide core and the core puller slide pin are slidably provided in the moving direction of the movable mold. Since we have provided a connecting part to connect,
The slide core could be slid reliably using the core puller slide pin, and cracking of the undercut portion could be completely prevented during product extrusion.

In addition, since the slide core can be slid and the mold opened without separating the fixed mold, the strength of the fixed mold does not decrease, and since it is an integrated fixed mold with no seams, there is no occurrence of burrs. , there was no need for deburring, and productivity was greatly improved.

Furthermore, the product no longer requires an opening for undercut processing, improving the strength of the mounting boss.
The degree of freedom in product design has improved, and the traditional taping work to close holes is no longer required.
Since it has a simple structure with individual core pullers and does not cause burrs or cracks, it has excellent effects such as greatly reducing the number of mold processing steps and mold repair steps.

[Brief explanation of drawings]

1 to 4 are diagrams showing one embodiment of the present invention. FIG. 1 is a longitudinal cross-sectional view showing the entire invented part, and FIG. 2 is a view taken along line A-A in FIG. Fig. 3 is a longitudinal sectional view partially showing the slide core in a state where it is slid downward, and Fig. 4 is a partially showing the state in which the mold is opened. FIG. Figures 5 and 6 are diagrams showing conventional injection molds, Figure 5 is a vertical cross-sectional view of the mold with the fixed mold divided, and Figure 6 is a diagram showing a mold using two core pullers. FIG. 3 is a vertical cross-sectional view of the mold. 1... Movable type, 2... Fixed type, 3... Slide core, 4... Core puller slide pin, 7... Spring, 8... Stopper, 9... Product.

Claims (1)

[Scope of utility model registration request] A slide core is provided to allow the movable type to slide,
On the other hand, a core puller slide pin was provided on the fixed mold so as to be slidable in the sliding direction of the slide core, and a connecting portion that could be inserted and removed in the moving direction of the movable mold was provided between the slide core and the end of the core puller slide pin. An injection mold having an undercut treatment structure.