JPS6212570Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a mold for plastic injection molding, and an object of the present invention is to provide a mold that can automatically separate the product from the plastic remaining in the runner section.

Plastic injection molds have a cavity for the product inside the mold, and sprues, runners, and gates that communicate with this to form a passage.The plastic material is injected from the outside after the mold is closed. It is injected into a mold by a molding machine, and is filled into the cavity through the sprue, runner and gate.

After the plastic filled in the mold has solidified, the mold is opened and the product is taken out. However, it is necessary to separate the product from the plastic remaining on the sprues, runners, etc. that are integrally formed with the product. (The separation method involves separating the product from the sprue,
After the molded product with the runner and gate integrally formed is taken out of the mold, the product, sprue, runner, and gate are cut and separated using external equipment or by hand.
There is also a way to separate them. ).

In general, when manufacturing a product by filling a mold with plastic material in a method of automatically cutting within a mold, the larger the product volume, the larger the gate cross-sectional area must be. The cutting resistance also increases, and when the mold is opened and the product is ejected, it is significantly deformed and becomes a defective product. Therefore, the cross-sectional area of each gate cannot be increased, and when the product thickness is 2.5 mm, the cross-sectional area of the gate is at most 6 mm ² , and usually less than 4 mm ² .

Therefore, if the product volume is large, a gate cross-sectional area commensurate with the volume is required, and a large number of gates must be provided. As a result, many weld marks caused by the number of gates and gate cutting marks caused by the gates themselves occur, resulting in a decrease in product quality and also making the mold expensive.

Conventionally, a mold as shown in FIG. 1 or 3 has been proposed for separating products as described above. That is, in the case shown in FIG. 1, a gate 2 is formed between a runner 1 and a product M, and the extrusion timings of the extrusion pin 3 of the product M and the extrusion pin 4 of the runner 1 are staggered to separate the gate 2 and the product M. This is to cut and separate the connection between the two.

However, although the one shown in Fig. 1 has the advantage of being able to be used in a narrow space, as shown in Fig. 2 a and b, a part of the gate 2 adheres to the edge of the product M, and it is necessary to remove it. requires post-processing. Furthermore, when cutting, there is a risk that the part of the product M connected to the gate 2 may be chipped, as shown in FIG.

Moreover, FIG. 3 shows a tunnel gate structure.
At the tip of the runner 5, there is a first gate 7 formed in a tunnel shape toward the lower side of the movable mold 6, and a second gate 7 toward the cavity 9 where the product M is formed along the extrusion pin 8 of the product M. When the mold is opened, the mold can be automatically cut and separated at the connecting portion between the first gate 7 and the second gate 10. However, in the case of the tunnel gate as described above, it has the advantage that it can be used in a narrow space, but even in this case, the residual plastic material of the second gate 10 is attached to the product M, so the second gate 10 is removed in a later process. A disadvantage is that the plastic material must be removed.

By adopting the configuration described in the claims of the utility model registration, the present invention allows the product to be reliably cut and separated from the plastic remaining on the sprue and runner at the same time as the mold is opened, and furthermore, the product can be cut off without chipping. It was also possible to obtain a mold that can form a product without any adhesion of part of the runner.

FIGS. 4 to 9 show an embodiment of the present invention. Next, the structure of the present invention will be explained based on these drawings.

A sprue 12 is formed in the fixed mold 11, and a groove 13 communicating with the sprue 12 is formed along the mating surface of the fixed mold 11 with the movable mold 14.

A rectangular recess 1 is formed on the mating surface of the movable mold 14 including the portion facing the sprue 12 and the recessed groove 13.
5 is formed, and an insert 16 is fitted into one end of the recess 15 in the longitudinal direction with a gap W,
The gap W is formed to have a length T.

The insert 16 is secured to the upper portions of both longitudinal ends of the recess 15 by stop plates 17, 17 which are screwed onto the movable mold 14, respectively, so as not to escape toward the fixed mold 11. The insert 16 is attached to the lower side of the stop plates 17, 17 so as to be slidable in the longitudinal direction of the recess 15 within the range of the gap W.

Further, a through hole 18 coaxial with the sprue 12 is formed in the insert 16, and communicates with the through hole 18, and the concave groove 13 of the fixed mold 11
A concave groove 19 is formed that matches the concave groove 13, and the concave groove 13 and the concave groove 19 constitute a runner 20. Further, a first gate 21 is formed in communication with the tip of the groove 19, and furthermore, the first gate 21
A second gate 2 communicating with the cavity 22 at the tip of the
3 is formed facing the fixed mold 11.

On the other hand, the fixed mold 11 has a protrusion 2 protruding toward the movable mold 14 on the opposite side of the sprue 12 to the side where the groove 13 is formed.
4 is formed, and the protrusion 24 is connected to the insert 1.
The tip of the protrusion 24 is inserted into a recess 26 formed at a position of the movable mold 14 corresponding to the through hole 25 . Note that the protrusion 24 is attached to the insert 16.
is in the mold closing position as shown in FIG.
6, and a gap W' having a length T' is formed on the outside of the through hole 25. Note that the relationship between T and T' is T<T'.

A pin 27 is attached to the tip of the protrusion 24 so as to face the short axis direction of the recess 15 and protrude from both ends of the protrusion 24 .
The through holes 25 of No. 6 are located on a pair of opposing sides on the short axis side,
A guide groove 28 is formed into which the pin 27 can be inserted.

The guide groove 28 is formed in the thickness direction of the insert 16, and the center portion of the thickness of the insert 16 is displaced by an amount t ₃ in the direction of the gap W' of the through hole 25.
It is formed into a mountain shape. Furthermore, Figure 4,
In FIGS. 5, 7 and 8, reference numeral 29 is a product ejection pin, 30 is a sprue 12 and a runner 2.
0, a residual plastic material extrusion pin, 31 a positioning member for the insert 16, and 32 a retaining member attached to the insert 16.

The present invention has the above-mentioned structure, and its operation and effect will be explained next. After the mold is closed, plastic material is injected from the tip of the sprue 12 to fill the cavity 22 with the plastic material. . After the plastic material has completely solidified, the movable mold 14 is moved in the direction of the arrow in FIG. 4 to open the mold. As the movable mold 14 moves, the pin 27 attached to the tip of the protrusion 24 of the fixed mold 11 reaches the lower side of the insert 16, and as the movable mold 14 moves further, the protrusion 24 The pins 27 protruding from both ends are inserted into guide grooves 28 formed in the through holes 25 of the insert 16, and guided by the guide grooves 28, the pins 27 are separated from the movable mold 14.

At this time, the guide groove 28 of the insert 16 is located at the center of the through hole 18 of the insert 16 in the thickness direction.
Since the pin 27 is bent by a displacement amount t ₃ in the opposite direction, as the pin 27 moves in the guide groove 28, it moves relatively inside the recess 15 along the mating surface of the movable mold 14, as shown in FIG. The product slides in the M direction.

As a result, the connecting portion between the second gate 23 and the product M is automatically separated as a flat cut surface by the shear force between the surface P formed on the movable mold 14 and the upper surface Q of the insert 16. be done.

In this case, in order to obtain a good cut surface, the second
The relationship between the thickness t ₁ of the gate 23, the thickness t ₂ of the product M, and the gap W between the recess 15 and the insert 16 is T>t ₂ >t ₁
It is necessary that the amount of displacement t ₃ of the bending of the guide groove 28 satisfies T>t ₃ >t ₂ .

In addition, the protrusion 2 formed on the fixed mold 11
4 is required to be at least the length of the sprue 12 since it is necessary for the plastic material remaining on the sprue 12 to completely leave the sprue 12.

As the movable mold 14 continues to advance further, the pin 27 is guided by the mountain-shaped guide groove 28 and the insert 16
is restored to its original state by the movement of the pin 27, and is maintained at this position by the maintenance member 32. Although not shown, the ejector pins 29 and 30 operate as shown in FIG. 8 by the operation of the ejector pin and the ejector plate, and the product M
The plastic material remaining on the sprue 12 and the runner 20 is extruded to form the product M.
can be removed from the mold (note that the maintenance member 32 can be omitted in some cases).

That is, in the present invention, the movable mold 14 when opening the mold
Using the moving movement of , the insert 16 mounted on the movable mold 14 is moved toward the mating surface of the movable mold 14, and the connecting portion between the second gate 23 and the product M is moved to the surface P of the movable mold 14. Since the cut surface is automatically cut by the shearing force between the surface Q and the surface Q of the insert 16, the cut surface can be cut as a flat cut surface. Therefore, there is no risk that the product M will be chipped during cutting, and there is also no risk that a part of the second gate 23 will stick.

In addition, as mentioned above, product M and sprue 12
After removing the plastic material remaining on the runner 20, by inserting the protrusion 24 of the fixed mold 11 into the through hole 25 of the insert 16,
The insert 16 operates in the opposite manner to the above, and the tip of the protrusion 24 is inserted into the recess 26 formed in the movable mold 14. In this case, since the insert 16 can always be set at the correct position by the positioning member 31 formed between it and the fixed mold 14, the molding operation can be continued after the mold is closed.

9, 10, 11, 12, and 13 respectively show other embodiments of the present invention (Fig. 9, 10, 11, 12 9 and 13, the same reference numerals as in FIGS. 4 to 8 indicate the same members),
The one shown in the figure has a protrusion 33 formed on the side of the movable mold 14 opposite to the second gate 23 formed on the insert 16, and a cylinder 34 is attached to the outside of the movable mold 14. It is something. In the case shown in FIG. 9, the insert 16 is moved forward or backward as appropriate toward the mating surface by using the cylinder 34 using oil pressure or air pressure.

Further, in FIG. 10, a protrusion 35 that projects the movable mold 14 outward is attached to the tip of the insert 16, and a toggle link 37 is attached between the tip of the protrusion 35 and the cylinder 36. The cylinder 36 is used to move the insert 16 forward and backward toward the mating surface as appropriate using oil pressure, air pressure, or the like.

In both of the structures shown in FIGS. 9 and 10, the cylinder 34 or 36 can be operated to slide the insert 16 in the direction of the mating surface after the plastic material injected into the mold has cooled and solidified. For,
It has the advantage of being able to operate independently of the opening of the mold.

11 and 12, the insert 16 is disposed at a position appropriately spaced from the sprue 12, and a first gate 21 is recessed in the insert 16 so as to communicate with the runner groove 13 recessed in the fixed die 11. A cavity 2 is formed in the insert 16 and communicates with the first gate 21.
2, and a drive member (not shown) for moving the insert 16 back and forth as described above is connected thereto, so that although the runner 20' bends when the gate is cut, the purpose is achieved.

In addition, FIG. 13 shows the second
A protrusion 38 protruding from the insert 16 is provided on the side of the movable mold 14 opposite to the gate 23, and a pin 27 is attached to the tip of the protrusion 38 so as to be perpendicular to the axis of the extrusion pin 30 (in the illustrated example, The guide groove 40 formed in the cam plate 39
The pin 27 is engaged with the cam plate 39 to integrally fix the cam plate 39 to the fixed mold 11. Said guide groove 4
0, when opening the mold, the insert 16 is moved to the left in FIG. 13 by T by the sliding action of the pin 27 and the guide groove 40, and then moved to the right in the figure by T.
When the insert 16 moves to the right end in FIG. 13, that is, when T ₄ =0, the center of the hole ₁₈ and the center of the push-out pin 30 are aligned. It is designed so that the sprue 12 can be protruded.

As described above, the present invention forms the gate part formed on the mating surface of the movable mold into a nest, and by sliding the nest in the direction of the mating surface, the plastic remaining on the gate part is removed. Since the connecting part between the material and the product part can be cut as a flat surface by the shearing force between the surface of the movable mold and the surface of the insert, there is no risk of the product being chipped during cutting. There is an advantage that the number of non-defective products can be greatly reduced, and since there is no risk that some plastic material of the gate will adhere to the product, there is no post-process to remove the adhered material.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the main parts of a conventional mold, Figures 2 a to c are cross-sectional views of the main parts of a conventional product cut away, and Figure 3 is the main part of a mold with a conventional tunnel gate structure. 4 is a sectional view of a main part of an embodiment of the present invention, FIG. 5 is a sectional view taken along line V-V in FIG. 4,
6 is a sectional view taken along the line in FIG. 5, FIGS. 7 and 8 are explanatory diagrams showing the operating state of the present invention, FIG. 11 is a plan view of a main part of a movable mold according to still another embodiment of the present invention; FIG. 12 is a sectional view taken along line XII-XII in FIG. 11; FIG. 13 is a sectional view of a main part of another embodiment of the present invention. 11... fixed mold, 12... sprue, 13,
19...Concave groove, 14...Movable mold, 15...Rectangular recess, 16...Insert, 17...Stopping plate, 18
...Through hole, 20, 20'...Runner, 21...
...First gate, 22...Cavity, 23...Second gate, 24...Protrusion of fixed mold, 25...
Through hole, 26... recess, 27... pin, 28, 4
0... Guide groove, 29, 30... Push-out pin, 31
... Positioning member, 33, 35, 38 ... Insert protrusion, 39 ... Cam plate, 34, 36 ...
Cylinder, 37...Toggle link.

Claims (1)

[Scope of utility model registration request] In a plastic mold, a rectangular recess is formed on the mating surface of the movable mold corresponding to the sprue and runner formed in the mold so as to communicate with a hole defined by a surface including a part of the product terminal line. is formed in the recess, and the insert is fitted into the recess so as to be able to move forward and backward through the gap, reaching into the hole and leaving an appropriate amount of gap in the depth direction of the hole. A gate is recessed in the mating surface of the insert, which communicates with a runner that communicates with the sprue and a cavity that forms a product space. A plastic molding die characterized in that a driving member that slides in a gap is coupled.