JPH04320820A - Mold device for injection molding - Google Patents

Abstract

PURPOSE:To make it possible to easily and surely discharge old resin remaining in a thermally insulated space between a bush and a mold in the case of the changeover of resin to be molded. CONSTITUTION:In a mold device for injection molding wherein the flow of resin flowing into a cavity 13 from a resin passage 16a is controlled by driving a needle valve 24 by means of an actuator 15, an engagement part 25a which is liquid-tightly engaged with the valve 24 between a closing position and an opening position is partially formed in the passage 16a. And a plurality of auxiliary passages 40 in communication with a portion of the passage 16a upstream of the part 25a and a thermally insulated space 21 are formed in a bush 16 and the actuator 15 is arranged so as to be held at a location where the needle valve 24 is engaged with the part 25a.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a mold apparatus for injection molding.

0002

BACKGROUND OF THE INVENTION As a conventional injection molding mold device, for example, the one described in Japanese Patent Application Laid-Open No. 150736/1983 is known, and this mold device is shown in FIGS. 4 and 5. . FIG. 4 is a sectional view, FIG. 5a is a partially enlarged sectional view, and FIG. 5b is a partially enlarged sectional view in a different state from FIG. 5a.

In FIG. 4, numeral 11 is a fixed mold that is fixed integrally with the template 80, and 12 is a movable mold that is supported so as to be able to move up and down relative to the fixed mold 11.
A cavity 13 having a shape corresponding to the molded product is formed between the molded product and the molded product. A recess 11a is formed in the upper surface of the fixed mold 11 in the figure, and a gate 17 that opens into the cavity 13 is formed at the bottom of the recess 11a. In addition, in FIG. 5, 36 is a cooling hole for promoting cooling of the resin in the cavity 13, and cooling water flows through this cooling hole 36.

Further, a runner member 14 and an air cylinder 15 are attached to the fixed mold 11, and the air cylinder 15 is arranged above the runner member 14 in the drawing. Runner member 1
4, the bush 16 is located on the fixed mold 11 side in the above-mentioned recess 11.
A distributing resin passage 14a is formed which is fixed corresponding to a and which communicates with an injection nozzle (not shown). In addition, 22
are heat insulating plates fixed to both the upper and lower surfaces of the runner member 14.

The bush 16 is constructed by integrally assembling an inner cylinder member 18 and an outer cylinder member 19, and is positioned in the recess 11a with the runner member 14 attached to the fixed mold 11, and is located at the bottom inside the recess 11a. A heat insulating space 21 is formed on the side. This bush 16 has a band heater 2 attached to the lower outer periphery in the figure.
3 is wound around the resin passage 1, which also penetrates vertically in the figure.
6a and branched from this resin passage 16a to form a distribution resin passage 1.
A branch resin passage 16b communicating with 4a is formed. The band heater 23 is connected to a heater drive circuit (not shown), and generates heat by receiving power from the heater drive circuit to heat the resin in the resin passage 16a.

As shown in detail in FIG. 5, the resin passage 16a has a small diameter portion 25a at the lower end in the figure that opens into the heat insulating space 21, and a large diameter portion 25b at the upper end in the figure on the runner member 14 side. The small diameter portion 25a and the large diameter portion 25b form the tapered portion 2.
Continuous with 5c. A guide bush 81 is fitted to the upper end of the resin passage 16a to close it off, and the needle valve 24 is inserted through the guide bush 81 so as to be able to move up and down.

The needle valve 24 has a resin passage 1 at the top.
The large diameter part 24a is loosely inserted into the large diameter part 25b of 6a, and the small diameter part 24b has a small diameter part 24b at the bottom that can be fitted in a substantially liquid-tight manner with the small diameter part 25a, and the gate 17 described above is provided at the lower end of the small diameter part 24b. A valve portion 24c that can be opened and closed is formed. This needle valve 24 has an upper end formed in an insertion hole 1 formed in the runner member 14.
4c is loosely inserted and engaged with the air cylinder 15, and is driven by the air cylinder 15, and is displaced up and down to open and close the gate 17 with the valve portion 24c.

The air cylinder 15 is constructed by fitting a cylinder body 27 into a mounting hole 26a formed in a mounting plate 26, and inserting an operating rod 28 into the cylinder body 27 so as to be vertically movable. The mounting plate 26 has two air passages 33a.
, 33b are formed, and the air passage 33a communicates in parallel from the port to two closing working chambers described later, and similarly, the air passage 33b communicates in parallel from the port to two opening working chambers described later. communicate.

The cylinder body 27 has two disc-shaped end plates 29a and 29b fitted into the upper and lower ends of the mounting hole 26a, and cylindrical members 30a and 3 are inserted between these end plates 29a and 29b.
0b and a disk-shaped partition plate equivalent portion 31 are provided. A substantially cylindrical space is defined between each end plate 29a, 29b and the partition plate 31, and pistons are arranged in each of these spaces, as will be described later.

[0010] The actuating rod 28 is connected to a first piston 28a.
The second piston 28b is fixed to a main body 32 that is integrally molded, and the lower end of the main body 32 is connected to the needle valve 24.
Connect with. The first piston 28a is vertically movably arranged in a space between the end plate 29a and the partition plate equivalent part 31, and vertically separates a closing working chamber 34a and an opening working chamber 35a, and similarly, The second piston 28b is vertically movably arranged in a space between the end plate 29b and the partition plate equivalent portion 31, and vertically separates a closing working chamber 34b and an opening working chamber 35b. The closing operation chambers 34a and 34b are connected to the air passage 33 described above.
b and the opening working chambers 35a, 35b communicate with the air passage 33a.

In such an injection mold device, when compressed air is supplied to the opening working chambers 35a and 35b of the air cylinder 15 and the rod 28 is moved upward, the needle valve 24 is moved upward. is held in an open position to open the gate 17 (see FIGS. 4 and 5a). Therefore, the molten resin supplied from the injection nozzle is transferred to the distribution resin passage 14.
a to the cavity 1 via the resin passage 16a and the gate 17.
It is filled within 3.

Further, when the molding process is completed, compressed air is supplied to the closing working chambers 34a and 34b of the air cylinder 15, and the rod 28 is moved downward to be held at the closed position. Therefore, the needle valve 24 moves downward, and as shown in FIG. 5b, the gate 17 is closed by the valve portion 24c, and filling of the resin into the cavity 13 is stopped.

[0013]

[Problems to be Solved by the Invention] However, in the above-mentioned conventional mold device, the fixed mold 11 is
etc., and the temperature is lower than that of the bush 16, etc., so the resin in the heat insulating space 21 becomes solidified at the portion where it contacts the fixed mold 11, and its fluidity decreases. As a result, resin tends to remain in the heat insulating space 21, and when changing the resin to be filled with a different type of resin, for example, when filling with resin of a different color, when new resin is supplied, the resin remaining in the heat insulating space 21 There is a problem in that the resin mixes with the new resin due to its viscosity, and the cavity 13 is filled with a mixture of two types of resin.

The present invention has been made in view of the above problems, and provides an injection mold device that can easily and quickly remove old resin remaining in a heat insulating space when changing the type of resin. The purpose is to make it easier to change the resin used.

[0015]

[Means for Solving the Problems] A bush is attached to a mold defining a cavity with a heat insulating space in between, a resin passage is formed in the bush and communicates with the cavity through the heat insulating space and a gate in series, and the resin passage is A needle valve that closes the gate in the closed position and opens the gate in the open position is inserted so that it can move between the closed position and the open position, and this needle valve is driven by an actuator to allow resin to flow into the cavity from the resin passage. In an injection mold device for controlling the flow of resin, the needle valve is partially fitted into the resin passage at a position between the closed position and the open position at a fitting part where the needle valve is fitted in a substantially liquid-tight manner. and forming a plurality of sub passages in the bush that communicates a portion upstream of the fitting portion of the resin passage with the heat insulating space, and positioning the actuator at a position where the needle valve fits into the fitting portion. It was configured so that it can be maintained.

[0016]

[Operation] In the injection mold device of the present invention, when switching the resin to a different type of resin, the actuator holds the needle valve in a position where it fits into the fitting portion. When resin is supplied in this state, the resin flows from the resin passage to the gate through the heat insulating space, and the resin remaining in the heat insulating space is removed by this resin. Therefore, even if the resin is changed, two types of resin will not be mixed in the gate, and
Resin switching can be done easily and quickly.

[0017]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 to 3 show an injection mold device according to an embodiment of the present invention, in which FIG. 1 is a sectional view, FIG. 2 is a sectional view in a different state from FIG. 1, and FIG. 3 is an enlarged sectional view of the main parts. be. In this embodiment, the same parts as those of the conventional mold apparatus described above are given the same numbers, and explanations and illustrations thereof are omitted.

In this embodiment, the resin passage 1 of the bush 16
Small diameter part 25a of 6a and small diameter part 24 of needle valve 24
The diameter of the small diameter portion 24 of the needle valve 24 is approximately equal to that of the needle valve 24.
b is formed so as to be able to fit into the small diameter portion 25a of the resin passage 16a in a liquid-tight manner. The bush 16 has a resin passage 1.
A plurality of cleaning passages (auxiliary passages) 40 are formed at equal intervals in the circumferential direction, communicating the tapered portion 25c of 6a with the upper part of the heat insulation space 21 in the drawing.

A cover member 41 is fitted into the opening of the mounting hole 26a on the runner member 14 side in which the air cylinder 15 is accommodated in the mounting plate 26, and the air cylinder 45 for positioning is provided on the cover member 41. An annular cylinder groove 41a is formed in the upper surface of the lid member 41 in the figure on the side of the air cylinder 15, and an annular piston 42 is fitted into this cylinder groove 41a so as to be able to move up and down. A working chamber 43 is defined within this cylinder groove 41a by a piston 42, and this working chamber 43
is in communication with an air passage 44 formed in the mounting plate 26.

An actuating piece 42a is integrally provided on the upper surface of the piston 42 on the side of the air cylinder 15 in the drawing, and this actuating piece 42a
2a passes through the end plate 29a airtightly so as to be vertically movable. The actuating piece 42a opens the opening actuating chamber 3 by the vertical movement of the piston 42.
5a, and the first piston 28a in a protruding state.
This contact defines the lower limit position of the rod 28 (see FIG. 2). Although not clearly shown in the figure, the piston 42 of the positioning air cylinder 45 is urged toward a lower position in the figure (see FIG. 1) by a return spring or the like.

In this embodiment, during molding, compressed air is discharged from the working chamber of the positioning air cylinder 45 to move the piston 42 downward, and as shown in FIG. immerse yourself in it. Similarly to the conventional mold apparatus described above, when filling the cavity 13 with resin, the air cylinder 15 moves the needle valve 24 upward to the open position to open the gate 17, and the filling of the resin into the cavity 13 When stopping the operation, the air cylinder 15 moves the needle valve 24 downward to the closed position to close the gate 17.

On the other hand, when changing the resin, as shown in FIG. 2, compressed air is supplied to the working chamber 43 of the positioning air cylinder 45, and this air cylinder 45 projects the working piece 42a into the opening working chamber 35a. let Then, when compressed air is supplied to the closing working chambers 34a and 34b of the air cylinder 15 and the needle valve 24 is moved from the open position to the closed position, the rod 28 is moved to the first piston 28a.
comes into contact with the actuating piece 42a and stops at the position defined by the actuating piece 42a (cleaning position).

Here, in the above-mentioned cleaning position, as shown in FIG.
As shown in FIG. 2, the needle valve 24 has a small diameter portion 24b that fluid-tightly fits into a small diameter portion 25a of the resin passage 16a to close the small diameter portion 25a, and a tapered portion 25c of the resin passage 16a passes only through the cleaning passage 40. It communicates with the upper part of the heat insulating space 21 . Then, when a small amount of new resin is supplied, the resin flows from the cleaning passage 40 into the insulation space 21 as shown by the arrow and flows toward the gate 17, removing the remaining resin attached to the wall surface of the fixed mold 11 in the insulation space 21. Push it out to gate 17. Therefore, when filling with a new resin later, no old resin remains, and the resin can be easily changed.

Note that when supplying resin at the above-mentioned cleaning position, it is desirable to stop the supply of cooling water to the cooling holes 36, and by flowing a high-temperature medium through the cooling holes 36, Furthermore, by providing a separate heat source such as a heater,
Furthermore, by applying fluororesin processing or the like to the wall surface of the heat insulating space 21, the remaining resin can be discharged more smoothly.

After this, from the gate 17 to the cavity 13
If only one type of resin flows out, that is, all the remaining resin is discharged, compressed air is discharged from the working chamber 43 of the positioning air cylinder 45 and the working piece 42a is moved to the end plate 29.
immerse it in a. Therefore, after this, as described above, by driving the needle valve 24 with the air cylinder 15, molding can be performed with new resin.

[0026]

[Effects of the Invention] As explained above, according to the injection mold device of the present invention, when changing the resin, new resin is supplied from the sub passage to the heat insulating space and remains in the heat insulating space. Since the old resin can be discharged, it is possible to reliably prevent the old resin from being mixed in when molding with new resin, and it is also possible to easily remove the remaining resin.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an injection mold device according to an embodiment of the present invention.

[Fig. 2] Cross-sectional view of the same mold device in a different state from Fig. 1

[Figure 3
】Enlarged cross-sectional view of the main parts of the same mold device

[Figure 4] Cross-sectional view of a conventional injection mold device

FIG. 5a is a partially enlarged sectional view of the same mold device, and FIG. 5b is a partially enlarged sectional view of the same mold device in a different state from FIG. 5a.

[Explanation of symbols]

11... Fixed mold (molding die), 12... Movable die (molding die), 13... Cavity, 15... Air cylinder (actuator), 16... Bush, 16a...
・Resin passage, 17...gate, 21...insulation space,
24... Needle valve, 24b... Small diameter part, 25
a...Small diameter part, 40...Cleaning passage (auxiliary passage), 45
...Air cylinder for positioning.

Claims (1)

[Claims] Claim 1: A bush is attached to a mold defining a cavity with a heat insulating space in between, a resin passage is formed in the bush and communicates with the cavity through the heat insulating space and a gate in series, and a resin passage is provided in the resin passage in a closed position. A needle valve that closes the gate and opens the gate in the open position is inserted so as to be movable between the closed position and the open position;
In an injection mold device in which the needle valve is driven by an actuator to control the flow of resin flowing into the cavity from the resin passage, the needle valve is located in the resin passage at a position between the closed position and the open position. In addition to partially forming a fitting part that fits almost liquid-tightly,
A plurality of auxiliary passages are formed in the bush to communicate between a portion upstream of the fitting portion of the resin passage and the heat insulating space, so that the actuator can be held in a position where the needle valve is fitted to the fitting portion. A mold device for injection molding, characterized in that: