JPH035291B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an injection mold that is formed to cut resin at a gate portion using a cutting block.

(Prior art) As a conventional injection mold, for example,
The one described in Japanese Patent No. 59-184634 is known.

In this conventional device, a product molding part is formed between a cavity main body and a core main body that can move toward and away from the cavity main body, and a nozzle bushing having an injection port for discharging molten resin is attached to the cavity main body. A cutting block formed between the cavity body and a runner connecting the gate and the injection port is attached to the core body so as to be movable forwards and backwards in a direction transverse to the approach and departure movement direction, and The injection port was formed so as to be inclined in the direction in which the cutting block retreated.

Incidentally, the cutting block was formed to slide by being directly transmitted with the telescopic drive of the hydraulic cylinder.

Therefore, in the above-mentioned conventional device, the resin on the product molding section side and the resin on the runner side are separated through the gate by sliding the cutting block backward so that the gate cut surface on the block side and the gate cut surface on the cavity side rub against each other. This allows the resin to be cut and separated.Furthermore, by slanting the injection port in the direction in which the cutting block retreats, the resin inside the injection port can easily escape when the cutting block slides backwards. This has the effect that the load for backward sliding can be reduced.

(Problems to be Solved by the Invention) However, in such conventional devices, since the cutting block is directly slid forward and backward by an actuator such as a hydraulic cylinder, it is difficult to slide the cutting block or
In order to fix it during molding, a large driving force was required for the reasons listed below.

○B When sliding the cutting block backward to cut and separate the gate resin, the cutting block is clamped between the cavity body and the core body and pressurized to clamp the mold, which places a large load on the cutting block.

(B) When injecting resin, injection pressure acts on the cutting block in the direction of pushing it out from the block slide, so it must be fixed against this pressure.

As described above, since a large driving force is required, a large actuator such as a hydraulic cylinder must be used, which poses a problem of increasing the size and cost of the device.

(Means for Solving the Problems) The present invention aims to solve the above-mentioned conventional problems, and to achieve this purpose, the present invention has a structure in which the cavity body and the core body are relative to each other. The mold can be closed and opened by moving toward and away from the mold, and a product forming part and a cutting block sliding part are formed between the two, and the cutting block is provided in the cutting block sliding part so as to be able to slide forward and backward. , the proximal end side of the cutting block is formed in a size such that it always protrudes from the cutting block sliding portion, and a slide cam insertion hole is formed in the protruding portion in a direction transverse to the forward and backward sliding direction, and , a slide cam is inserted into the slide cam insertion hole, the slide cam is moved by an actuator, a mutual sliding surface is formed between the slide cam insertion hole and the slide cam, and the direction of movement of the slide cam is The means is such that the mutual sliding surface has an inclination angle.

(Function) Therefore, in the injection mold of the present invention, since the mutual sliding surface between the slide cam and the slide insertion hole and the moving direction of the slide cam have an inclination angle θ, the actuator Because the drive is transmitted so that the slide stroke amount of the cutting block is smaller than the drive stroke amount of the
The driving force of the actuator required to slide the cutting block backward or to fix it during injection molding can be reduced in proportion to its stroke ratio.

(Example) Hereinafter, the example shown in FIGS. 1 to 7 will be described in detail.

First, the configuration of the embodiment will be explained.

As shown in the figure, the injection mold according to one embodiment of the present invention mainly includes a cavity body 10, a core body 20, a cutting block 30, and a block slide mechanism 40.

The cavity main body 10 and the core main body 20 are
As shown in the figure, there is a mold that forms a product forming part 50 for forming the product W when the mold is clamped, and between the two, the product forming part 50 is formed when the mold is clamped.
A block slide portion 60 is formed which communicates with the block slide portion 60 through the gate 51.

The cavity main body 10 is fixed to a mounting plate 12 via a spacer 11, and the mounting plate 12 is a stationary side during mold clamping in an injection molding device (not shown), and is used in an injection device that injects molten resin. installed.

Further, a nozzle bush 14 is attached to the cavity main body 10, and the nozzle bush 14 has an injection port 13 at its tip and opens into the block slide part 60. There is.
Molten resin P is discharged from an injection device (not shown) into the nozzle portion 16 and is injected from the injection port 13 via the runner block 15 and the nozzle bush 14.

Incidentally, the nozzle bush 14 and the runner block 15 are provided with a heater 17 to prevent the resin P flowing therefrom from solidifying.

The core body 20 is fixed to a mounting plate 22 via a spacer 21, and this mounting plate 22 is a movable side during mold clamping in an injection molding apparatus (not shown), and is a drive device that drives the mounting plate 22. The core body 20 is attached to the cavity body 10.
It is now possible to approach and depart from the enemy.

In addition, a push-out plate 25 is provided in a space 24 surrounded by the core body 20, the spacer 21, and the mounting plate 22, and a coil spring 26 installed between the push-out plate 25 and the core body 20 A resilient force is applied to the extrusion plate 25 toward a stopper 27 fixed to the mounting plate 22.

The extrusion plate 25 is provided with a return pin 251 for ensuring that the extrusion plate 25 returns to the state shown in FIG.
The molded resin product is transferred to the core body 20 by moving the core body 20.
An ejector pin 252 for taking out the ejector pin 252 and an operating pin 25 for operating the ejector pin 36 described later.
3 and are provided.

The block slide portion 60 is a portion on which the cutting block 30 slides. , a core-side sealing surface 64 on the core body 20 side, an abutment surface 65, and a core-side sliding surface 66 (FIG. 3).

The cavity side gate cut surface 61 has a third
As shown in the figure, this is a surface formed adjacent to the gate 51 in a direction perpendicular to the direction Q of movement toward and away from the core body 20 . At the position of the gate 51, a cavity-side gate cut edge 67 is formed by the product molding portion 50 and the cavity-side gate cut surface 61. This cavity-side gate cut edge 67 is formed at an obtuse angle greater than 90° because the product forming portion 50 is always inclined inward with respect to the direction of approach and separation of the core body 20 and the cavity-side gate cut surface 61 is at a right angle. Something,
Therefore, the cavity side gate cut edge 67 has high strength and is difficult to chip.

As shown in FIG.
The cutting block 3 extends from the cavity side gate cut surface 61 to the injection port 13.
It is formed to be inclined in the direction of expansion with respect to the backward sliding direction S of zero.

The cavity-side rubbing surface 63 is formed from the injection port 13 to the lower end of the cavity main body 10 so as to be slightly inclined toward the cavity-side gate cut surface 61 .

The core-side sealing surface 64 forms a sealing surface 70 that comes into close contact with the later-described block-side sealing surface 35 of the cutting block 30 during mold clamping to prevent the resin P from leaking from the gate 51 to the abutting surface 65. (FIG. 2), this core-side sealing surface 64 is formed on the same plane as the cavity-side gate cut surface 61 (FIGS. 3 and 5).

The abutment surface 65 is a surface with which the tip end surface of the cutting block 30 comes into close contact with the gate 51 when the cutting block 30 is advanced and slid.
It is formed on the back side of the wall (Figures 3 and 5).

The core side sliding surface 66 is connected to the cutting block 3.
0 is the surface that slides forward and backward by rubbing against each other (Figures 3 and 6).

The cutting block 30 cuts the resin P at the gate 51 in order to separate the resin P in the product molding section 50 from the resin P on the injection port 13 side. As shown in the figure, the core body 20 is attached to a block slide mechanism 40 that supports the block slide portion 60 so as to be slidable forward and backward.

Further, this cutting block 30 is formed in a shape that comes into close contact with each surface of the block slide portion 60 when the mold is clamped with the distal end surface 31 in contact with the abutment surface 65, and the shape of the cutting block 30 is such that it comes into close contact with each surface of the block slide portion 60, and The runner 62 forms a runner 32 that creates a space that communicates the injection port 13 and the gate 51, and between the runner 32 and the tip surface 31 there is a block side gate cut edge 33 that is continuous with the block side gate cut edge 33. A gate cut surface 34 is formed.

Moreover, this block side gate cut surface 34 is
A block-side sealing surface 35 is provided on the distal end surface 31 side, which comes into close contact with the core-side sealing surface 64 to form a sealing surface 70 when the cutting block 30 enters.

Further, the cutting block 30 is formed in such a length that its proximal end side protrudes from the block slide part 60 even when it is completely inserted into the block slide part 60, and the always protruding part has a block side entry cam surface 371. A slide cam insertion hole 37 having a block side retraction cam surface 372 is formed.

This slide cam insertion hole 37 is inserted in the axial direction.
_L1 is formed in a direction perpendicular to the backward sliding direction S of the cutting block 30 (FIG. 7).

Reference numeral 36 shown in FIG. 2 is an ejector pin that removes the solidified resin P inside the runner 32 when pushed by the operating pin 253. This ejector pin 36 is slid toward the operating pin 253 by a spring 361. energized.

The block slide mechanism 40 is a mechanism for sliding the cutting block 30 forward and backward.
1, a hydraulic cylinder 42, a support member 43, a stopper 44, and the slide cam insertion hole 37 (FIG. 7).

The slide cam 41 has a cam portion 45 on the tip side.
and the slide guide portion 46 on the proximal end side are bent in a dogleg shape. The slide guide portion 46 is supported by the support member 43 so as to be inclined by a cam angle (inclination angle) θ with respect to the slide cam insertion hole 37 and to slide parallel to the direction of approach and separation of the core body 20. and is connected to a hydraulic cylinder 42. Note that the support member 43 and the hydraulic cylinder 42 are attached to the core body 20.

The cam angle θ is approximately 11°.

The cam portion 45 forms a cam mechanism with the slide cam insertion hole 37 so that the stroke amount of the cutting block 30 is smaller than the stroke amount of the hydraulic cylinder 42. , an entry slide cam surface 451 that is slidably formed to have approximately the same diameter as the slide cam insertion hole 37 and that rubs against the block side entry cam surface 371 to form a mutual sliding surface; and the block side retraction cam surface. A retraction slide cam surface 452 that rubs against 372 to form a mutual sliding surface is formed.

Therefore, the cam surfaces 371, 451, 372, 452 forming the mutual sliding surfaces and the sliding direction of the slide cam 41 are inclined by the cam angle θ.

The slide cam 41 slides the cutting block 30 forward by transmitting drive while the two entry cam surfaces 371 and 451 rub against each other due to the extension of the hydraulic cylinder 42, and the two retraction cams are moved by the contraction of the hydraulic cylinder 42. Cutting block 3
Slide 0 backwards.

The ratio of the stroke amount of the cutting block 30 to the stroke amount of the hydraulic cylinder 42 is as follows:
Since the axial direction L ₁ of the cam portion 45 and the slide cam insertion hole 37 and the axial direction L ₂ of the slide guide portion 46 and the hydraulic cylinder 42 form a cam angle θ (θ≒11°), the cam angle is 0.2 (≒ tan11゜).

Therefore, the cutting block 30 can be slid with a driving force of the hydraulic cylinder 42 that is 20% of the load applied to the cutting block 30, and the driving force of the hydraulic cylinder 42 is less than the load applied to the cutting block 30. The relationship that the cutting block 30 slides due to force holds within the range 0°<|θ|<45°.

Further, the stopper 44 is connected to the cutting block 30.
When completely slid in, it engages with the slide cam 41 (engagement in the backward sliding direction S of the cutting block 30), and the cutting block 30 is moved by the injection pressure of the resin P from the injection port 13. This is provided in the cavity main body 10 to prevent the rear end from sliding.

Incidentally, FIG. 4 is a perspective view showing the product W, and also shows a portion R of the runner 32 and a portion G of the gate 51.
This figure shows the state in which it is taken out in a connected state.

Next, the operation of the embodiment will be explained.

To explain step-by-step how the product W is completed, first, the hydraulic cylinder 42 is extended and the slide cam 41 is slid until it is engaged with the stopper 44, thereby engaging the block side entry cam surface 371. A component force is generated between the cutting block 30 and the slide cam surface 451 in the sliding direction of the cutting block 30, and the cutting block 30 is slid in the sliding direction.

Then, when the tip end surface 31 of the cutting block 30 comes into contact with the abutment surface 65, the cutting block 30
At the same time, the slide cam 41 comes into engagement with the stopper 44, but at this time, the block-side gate cut surface 34 contacts the cavity-side gate cut surface 611, and the block-side seal surface 35 contacts the core-side seal surface 64. Then, the tip end surface 31 is in close contact with the abutment surface 65, or rather, the cutting block 30 is in close contact with each surface of the block slide portion 60.

Next, after the core body 20 is brought close to the cavity body 10 by a drive device (not shown) and the mold is clamped, molten resin P is discharged into the nozzle part 16 from an injection device (not shown). The molten resin P is
The liquid is injected from the injection port 13 via the runner block 15 and nozzle bush 14 to the runner 32 and product forming section 50.

At this time, on the side closer to the core body 20 than the gate 51, the block-side sealing surface 35 and the core-side sealing surface 64 come into close contact to form a sealing surface 70, and this sealing surface 70 is caused by the movement of the core body 20. Since the mold clamping pressure is applied, the resin P does not enter between the tip surface 31 of the cutting block 30 and the abutting surface 65 due to the injection pressure.

Furthermore, although a large pressure is applied to the cutting block 30 in the backward sliding direction due to the injection pressure, the pressure transmitted to the hydraulic cylinder 42 is reduced to 1/5 due to its stroke ratio, so the cutting block 30 can be moved with less force. The backward slide can be restricted, and since the slide cam 41 is engaged with the stopper 44, the cutting block 30 can be prevented from popping out (sudden backward slide) due to unexpected sudden pressure.

Thereafter, when the resin P is solidified and the product W is molded, the cutting block 30 is slid backward in order to separate the product W from the resin P on the runner 32 side.
This sliding of the cutting block 30 is performed by the sliding of the slide cam 41 due to the contraction of the hydraulic cylinder 42, and the cam portion 45 and the slide cam insertion hole 37 in the sliding direction of the slide cam 41.
A stroke ratio of 0.2 between the slide of the cutting block 30 and the hydraulic cylinder 42 is obtained by the inclination angles of the cam surfaces 452, 372 on both retreating sides of the cutting block 30, so that the load applied to the cutting block 30 is On the other hand, the cutting block 30 is slid backward by the driving force of the hydraulic cylinder 42 of 20%, and furthermore, the core side sliding surface 66 is connected to the cavity side gate cut surface 6.
1, so that a gap is created between the cutting block 30 and the block sliding part 60, and the load on the cutting block 30, such as mold clamping pressure, is reduced. The cutting block 30 is slid by the driving force.

By sliding the cutting block 30 backward as described above, the cavity side gate cut edge 67
The solidified resin P is cut at the gate 51 by the contact between the block-side gate cut edge 33 and the rubbing between the cavity-side gate cut surface 61 and the block-side gate cut surface 34.

Furthermore, when the cutting block 30 slides backward, since the cavity side runner surface 62 is inclined in the direction of expanding with respect to the backward sliding direction,
As shown in FIG. 6, the resin P in the runner 32 peels off from the cutting block 30 and becomes easy to remove.

Thereafter, the core body 20 is moved away from the mold to open the mold and take out the product W.
is pushed out by the push-out pin 252 and removed from the core body 20. Furthermore, the solidified resin P in the runner 32 portion is pushed by the ejector pin 36 and removed by the operation of the operating pin 253.

As explained above, in the injection mold according to the embodiment of the present invention, since the cutting block 30 can be slid backward with a small driving force,
The hydraulic cylinder 42 can be made small, and the device can be made compact and costs can be reduced.

Furthermore, by forming the cavity side gate cut surface 61 at right angles to the direction of approach and separation of the core body 20, the cavity side gate cut edge 67 can be
The angle is always larger than 90°, making it stronger and less likely to chip.

Further, since the cutting block 30 is wedge-shaped, if excessive cutting occurs during molding, the tip can be cut off and molding can be performed again.

Furthermore, by forming the sealing surface 70, the resin P is transferred from the gate 51 to the tip surface of the cutting block 30.
It is possible to prevent leakage of resin P, and there is no need to remove the resin P solidified on the tip surface 31, resulting in labor savings.

In addition, the block-side sealing surface 35 forming this sealing surface 70 is exposed on the front side when the mold is opened, and the core-side sealing surface 64 is also only slightly on the back side from the exposed surface. Even when the resin P adheres, it is easy to remove it.

Moreover, since the stroke ratio between the cutting block 30 and the hydraulic cylinder 42 is 0.2 due to the block slide mechanism 40, the cutting block 30 can be slid with a driving force of 20% of the load on the cutting block 30. In addition, the driving force required to restrict the backward sliding of the cutting block 30 due to the injection pressure of the resin P can be reduced to 20%, allowing the hydraulic cylinder 42 to be made smaller.

In addition, by providing the slide cam 41 and the stopper 44, it is possible to prevent the cutting block 30 from suddenly popping out.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and even if there are design changes within the scope of the gist of the present invention, they are included in the present invention. It will be done.

For example, in the embodiment, the stroke insertion hole has an inclination of approximately 11 degrees with respect to the driving stroke direction of the actuator, but the inclination angle may be any angle as long as it is less than ±45 degrees.

Further, although a hydraulic cylinder is used as the actuator in the embodiment, any other fluid pressure cylinder or the like may be used.

(Effects of the Invention) As explained above, in the injection mold of the present invention, the driving force of the actuator is smaller than that of the conventional one, so the actuator can be made smaller, resulting in smaller equipment and lower costs. This has the effect of making it possible.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an injection mold according to an embodiment of the present invention, Fig. 2 is a side view showing a cutting block of the mold according to the embodiment, and Fig. 3 is a block slide portion of the mold according to the embodiment. FIG. 4 is a perspective view showing a product molded by the mold of the example, FIGS. 5 and 6 are diagrams showing the functions of the main parts of the mold of the example, and FIG. FIG. 3 is a side view showing the block slide mechanism of the mold according to the embodiment. 10... Cavity body, 20... Core body,
30... Cutting block, 37... Slide cam insertion hole, 41... Slide cam, 42... Hydraulic cylinder (actuator), 60... Block, 3
71... Block side approach cam surface, 372... Block side retreat cam surface, 451... Approach slide cam surface, 452... Backward slide cam surface.

Claims (1)

[Scope of Claims] 1. A cavity main body and a core main body are provided so that the mold can be clamped and opened by relative movement toward and away from each other, and a product forming part and a cutting block slide part are formed between the two, and the cutting A cutting block is provided in the block sliding portion so as to be slidable forward and backward, and the proximal end side of the cutting block is formed in a size such that it always projects from the cutting block sliding portion, and the protruding portion is provided with a cutting block that can be slid forward and backward. A slide cam insertion hole is formed in a direction transverse to the slide cam insertion hole, and a slide cam is inserted into the slide cam insertion hole, and the slide cam is moved by an actuator, and the slide cam is moved between the slide cam insertion hole and the slide cam. A mold for injection molding, characterized in that a mutual sliding surface is formed, and the moving direction of the slide cam and the mutual sliding surface have an inclination angle.