JP2670363B2 - Gate cutting device for plastic mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a gate cutting device of a plastic mold for cutting and separating plastic solidified by a gate from a product.

(Prior Art) Automatically cutting plastic solidified in a gate from a product has been conventionally performed.
Shown in the figure.

In FIG. 5 (a), a molding die 1 is composed of a fixed die 2 attached to a fixed mounting plate (not shown) of the molding machine and a movable die 4 attached to a movable mounting plate 3 of the molding machine. It is configured. The extrusion plate 5 provided between the movable mounting plate 3 and the movable mold 4 is provided with a product extrusion pin 6 and a runner extrusion pin 7. Of these, the runner extrusion pin 7
Can be moved in the axial direction by the dimension A with respect to the push plate 5.

In such a mold 1, the molten plastic supplied from the nozzle of the molding machine is injected into the cavity 10 through the runner 8 and the gate 9, and is cooled and solidified as shown in FIG. 5 (a). Molded as product 11. After the molding, the movable mold 4 is separated from the fixed mold 2 to open the mold, and then the extrusion plate 5 is extruded to move upward. In the initial stage of this extrusion, while the extrusion plate 5 is moving by the amount corresponding to the dimension A, only the product extrusion pin 6 is pressed by the extrusion plate 5.
And the runner push-out pin 7 remains stopped. Therefore, as shown in FIG. 5B, the product 11 is pushed up by the product extruding pin 6 and extruded from the movable mold 4, but the plastic 12 solidified in the runner 8 is moved to the movable mold 4.
, Which results in the product 11 being separated from the solidified plastic 12 in the runner 8 by being torn off at the gate 9 portion. After that, as shown in FIG. 5 (c), the runner pushing pin 7 also moves upward, whereby the plastic 12 solidified in the runner 8 is pushed out from the movable die 4.

(Problems to be Solved by the Invention) However, conventionally, since the product 11 is cut off from the plastic 12 solidified in the runner 8 and the gate 9, the cut surface becomes coarse as shown in FIG. There was a problem that finishing work had to be done later.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a gate cutting device of a plastic molding die capable of reliably and beautifully cutting and separating a product and a plastic solidified in a gate.

[Means for Solving the Problems] The gate cutting device for a plastic molding die of the present invention is composed of a movable die and a fixed die, and the plastic supplied from the nozzle of the molding machine is used for the movable die. A molding die for molding a product by injecting into a cavity from a gate formed between mating surfaces with a fixed die, the groove having at least a part of the gate, and one of the movable die and the fixed die And a resilient member for urging the cutter member in a direction protruding toward the other of the movable mold and the fixed mold in a direction intersecting the gate. , When the movable mold is butted against the fixed mold, the cutter member relatively moves in the direction in which the cutter member comes into the one mold against the elastic force of the elastic member due to the contact with the other mold. Is After the molding of the product, at the time of mold opening for moving the movable mold away from the fixed mold, the elastic member causes the elastic member to repel the cutter member toward the other mold side in response to the movement of the movable mold. The relative movement causes the cutter member to move relative to the product and cut and separate the plastic solidified at the gate from the product.

(Operation) When the movable mold moves in a direction away from the fixed mold when the mold is opened after molding, the cutter member moves in a direction intersecting the gate by the elastic force of the elastic member. Then, the cutter member cuts and separates the solidified plastic at the gate from the product.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

First, as shown in FIG. 1, the molding die 21 includes a fixed die 22 and a movable die 23, and the fixed die 22 is mounted on a fixed mounting plate (not shown) of the molding machine. It is attached to the movable attachment plate 24 via a spacer (not shown).
Of these two molds 22 and 23, the movable mold 23 has a mold body 25,
And a nest 26 attached to the mold body 25,
Between the convex portion 26a of the insert 26 and the concave portion 22a of the fixed mold 22, the product S
A cavity 27 for forming (see FIG. 2) is formed. The fixed mold 22 is provided with a spool 28 for receiving a supply of molten plastic from a nozzle (not shown) of the molding machine.
A groove-like runner 29 is formed from a portion immediately below the cavity 27 toward the cavity 27, and the runner 29 and the cavity 27 are communicated by a gate 30 called a side gate. A plurality of cavities 27 are formed, and a runner 29 is provided with a spool.
A plurality is formed radially from a portion directly below 28.

On the other hand, between the movable die 23 and the movable mounting plate 24, the pushing plate 31
Are arranged so that they can move up and down. And this extrusion plate 31
The product extrusion pin 32 whose tip faces the cavity 27,
A runner push-out pin 33 whose tip faces the inside of the runner 29 is attached.

Now, at least a part of the gate 30, in the present embodiment, the bottom surface and the three side surfaces of the left and right side surfaces are constituted by one of the fixed die 22 and the movable die 23, for example, a cutter member 34 provided on the movable die 23. Has been done. That is, as can be understood from FIGS. 3 and 4, the cutter member 34 has a square bar shape, and the upper end surface portion thereof faces the cavity 27 side as shown in FIGS. 3 and 4. A groove 35 that is gradually narrower and has a shallower bottom is formed, and the groove 35 constitutes the three surface portions of the gate 30. An acute corner at the end on the cavity 27 side of the bottom surface of the groove 35 is configured as a blade 35a. The remaining upper surface of the gate 30 is constituted by the fixed mold 22.

Here, the mounting structure of the cutter member 34 will be described. In the insert 26 of the movable die 23, a vertically extending support hole 36 having a large diameter portion 36a at the lower end portion is formed. The cutter member 34 is slidably inserted into and supported by the support hole 33 such that the wide head 34a formed at the lower end is positioned within the large-diameter portion 36a. At this time, the vertical length of the large diameter portion 36a is formed to be larger than the thickness of the head portion 34a, and a gap G is formed between the two, and the cutter member 34 crosses the gate 30 by an amount corresponding to the gap G. You can move in any direction. In addition, the gap G is the gate 30
Is set to have substantially the same dimension as the depth D (see FIG. 4) of the deepest part. A hole 37 communicating with the large-diameter portion 36a of the support hole 36 is formed in the mold body 25 of the movable die 23.
A compression coil spring 38 as an elastic member is housed therein. The compression coil spring 38 is compressed by the set screw 39 screwed into the lower end portion of the hole 37, and the resilience of the compression coil spring 38 causes the cutter member 34 to move upward toward the fixed mold 22 that is the other mold. I am biased.

 Next, the operation of the above configuration will be described.

It is assumed that the movable die 23 is now separated from the fixed die 22 downward. In this state, the cutter member 34 is moved upward by the elastic force of the compression coil spring 38 until the head portion 3a contacts the inner upper surface of the large diameter portion 36a, and the upper end portion projects from the upper surface of the movable die 23. . When the movable mounting plate 24 moves upward and the movable die 23 is abutted against the fixed die 22, the upper end of the cutter member 34 first contacts the fixed die 22, and then the movable die 23 is fixed. Since the cutter member 34 comes into contact with the mold 22, the cutter member 34 is relatively pressed against the movable mold 23 so as to enter the movable mold 23 while compressing and compressing the compression coil spring 38, as shown in FIG. The gate 30 brings the runner 29 and the cavity 27 into communication with each other.

In this state, when molten plastic is injected from a nozzle (not shown) of the molding machine, the molten plastic is injected into the cavity 27 from the gate 30 through the spool 28 and the runner 29 in order, and is filled into the cavity 27. It

Now, when the molten plastic filled in the cavity 27 is cooled and solidified to be molded as the product S, the movable mounting plate 24 is moved downward to open the movable mold 23 from the fixed mold 22. . At this time, since the product S is in a state of biting the convex portion 26a of the nest 26 due to shrinkage at the time of solidification, the concave portion 22a of the fixed die 22 remains attached to the movable die 23 as shown in FIG. Is extracted from. Further, the plastic P solidified in the spool 28, the runner 29 and the gate 30 is also bitten by the biting portion Q on the movable die 23.
It is detached from the fixed mold 22 while adhering to. On the other hand, the movable type 23
Begins to separate from the fixed mold 22, the cutter member 34 is relatively moved upward by the elastic force of the compression coil spring 38 so as to intersect the gate 30 with respect to the movable mold 23, and therefore to the product S. Therefore, the plastic P solidified in the spool 28, the runner 29, and the gate 30 is cut at the end of the gate 30 on the product S side by the blade 35a of the cutter member 34, as shown in FIG. To be separated. Then, when the mold opening is completed, the extruding plate 31 moves upward in the figure, whereby the product pushing pin 32 pushes the product S from the convex portion 26a, and
The runner push pin 33 is connected to the spool 28, the runner 29 and the gate 30.
The solidified plastic P is extruded from the movable mold 23.

As described above, according to the present embodiment, the cutter member is opened when the mold is opened.
The spool 28, the runner 29 and the gate 30 are
The plastic P solidified therein can be automatically cut and separated from the product S. This cutting is performed by the blade 35a, unlike the conventional tearing, so that the plastic P solidified in the spool 28, the runner 29 and the gate 30 can be reliably cut and separated from the product S. In addition, since the cutting is performed by the blade 35a, unlike a conventional tearing machine, a beautiful cut surface is obtained, and the need for post-finishing is eliminated. Moreover, the cutter member 34 is moved relative to the fixed mold 22 by the mold closing operation of the movable mold 23 so as to enter the movable mold 23 while compressing and compressing the compression coil spring 38. When the mold opening operation is performed, the plastic P is relatively moved so as to protrude from the movable mold 23 by the stored elastic force of the compression coil spring 38 and cuts the plastic P. Alternatively, a drive source such as a hydraulic cylinder is not required, and the configuration can be made at low cost.

In the above-described embodiment, the cutter member forms the three surface portions of the bottom surface portion and the left and right side surfaces of the gate. However, this may constitute only the bottom surface portion, and the cutter member may have a gate hole. May be formed to constitute the entire gate.

EFFECTS OF THE INVENTION As described above, according to the present invention, at least a part of the gate is configured by a cutter member that is movable in a direction intersecting with the gate, and the cutter member is moved by the movement of the movable die during mold closing. The spring member is relatively moved so as to enter one of the dies, and accumulates an elastic force. With the movement of the movable mold when the mold is opened after molding, the cutter member is caused to accumulate by the accumulated elastic force. Since an elastic member that moves relatively so as to protrude from the mold is provided, the solidified plastic product at the gate can be reliably cut and separated by the cutter member, and the cut portion becomes beautiful, eliminating the need for post-finishing, and It is possible to obtain excellent effects such as no need to provide a special drive source such as a pneumatic or hydraulic cylinder for moving the cutter member.

[Brief description of the drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a vertical sectional side view showing a mold closed state, FIG. 2 is a vertical sectional side view showing a gate cutting state, and FIG. FIG. 4 is a plan view and FIG. 4 is a partially enlarged perspective view of the cutter member. In addition, the fifth
6A to 6C are longitudinal side views showing a conventional gate cutting configuration, and FIG. 6 is a longitudinal side view showing a cutting state by the conventional cutting configuration. In the figure, 21 is a molding die, 22 is a fixed die, the other die, 23 is a movable die, 27 is a cavity, 28 is a spool, 29 is a runner,
30 is a gate, 34 is a cutter member, 35 is a groove, 35a is a blade, and 38 is a compression coil spring (drive means).

Claims (1)

(57) [Claims] 1. A product comprising a movable mold and a fixed mold, wherein plastic supplied from a nozzle of a molding machine is injected into a cavity from a gate formed between mating surfaces of the movable mold and the fixed mold to produce a product. In a molding die to be molded, a cutter member having a groove constituting at least a part of the gate, and being provided in one of the movable die and the fixed die so as to be movable in a direction intersecting with the gate, An elastic member for urging the cutter member in a direction projecting to the other mold side of the movable mold and the fixed mold, wherein the cutter member is the other of the other molds when the movable mold is abutted against the fixed mold. When the mold is opened by moving the movable mold away from the fixed mold after the product is molded, it is relatively moved in the direction of entering the one mold against the elastic force of the elastic member by contact with the mold. Movement of the movable type Accordingly, the elastic member relatively moves in a direction projecting the cutter member to the other mold side by its elastic force, so that the cutter member relatively moves with respect to the product and solidified at the gate. A plastic molding type gate cutting device, which is configured to cut and separate from the product.