JPH0768602A - Valve gate for injection molding - Google Patents

Abstract

PURPOSE:To prevent burrs from occurring at a gate portion of a molding. CONSTITUTION:A valve 40 is rotatably provided in a horizontal direction. A channel resin path 44 is formed on the side peripheral surface of the nose of this valve 40. A gate 34 is provided in a position eccentric to the rotational center of the valve 40. During an injection process, the resin path 44 and the gate 34 are matched and the gate 34 is opened. After an injection process, the valve 40 is rotated to separate the gate 34 and the resin path 44, and the gate 34 is blocked by the blocking portion 43. The method of blocking the gate 34 by the blocking portion 43, using the rotation of the valve 40, ensures a separation of the gate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve gate device for an injection molding die.

[0002]

2. Description of the Related Art A hot runner mold used for injection molding of a thermoplastic resin always keeps the resin from the sprue and runner to the vicinity of the gate in a molten state in order to enhance the molding efficiency. On the other hand, since the resin filled in the product-shaped cavity must be cooled and solidified, in the hot runner mold, it is necessary to open and close the gate part by some means. As a method for opening and closing the gate portion, there is a valve gate method in which the gate is mechanically opened and closed by a valve.

Here, an example of a conventional valve gate type mold device will be described with reference to FIG. Reference numeral 1 is a fixed-side mold member, 2 is a movable-side mold member, and these mold members 1 and 2 move in the vertical direction in the drawing to open and close, and form a product-shaped cavity 3 inside during mold clamping. To do. A gate bush 4 is embedded and fixed in the fixed-side mold member 1 so as to face the cavity 3, and the gate bush 4 is opened at the tip end facing the cavity 3 with the vertical direction in the drawing as an axial direction. Have five. Further, a tubular valve casing 7 in which a heater 6 is built in the gate bush 4 and whose lower end portion in the drawing is coaxially fitted and fixed is embedded in the fixed-side mold member 1, and the valve casing 7 A guide bush 8 is coaxially fitted and fixed to the upper portion of the inner peripheral surface in the figure. The runner 10 of the manifold 9 communicates with a gate passage 12 in the valve casing 7 through a manifold passage 11 formed on the upper side of the valve casing 7 in the drawing, and the gate 5 is provided in the gate passage 12. It is connected. Further, in the gate passage 12, a pin-shaped valve 13 that is positioned coaxially with the gate 5 and opens and closes the gate 5 is provided so as to be movable in the vertical direction in the figure. This valve 13
Is slidably held by the guide bush 8 in the gate passage 12 so that its axis coincides with the axis of the gate 5. Then, by the vertical movement of the valve 13,
The lower end of the valve 13 shown in the drawing is removably fitted into the gate 5 to open and close the gate 5.

Next, the operation of the above configuration will be described. At the time of molding, the fixed side mold member 1 and the movable side mold member 2 are clamped, and as shown by the solid line in FIG. 9, the valve 13 is raised and the gate 5 is opened. The molten resin is injected from the nozzle of. This resin passes through the sprue, the runner 10 of the manifold 9, the manifold passage 11 and the gate passage 12, and the opened gate 5
To flow into the cavity 3 and fill the cavity 3. After this filling is completed, the valve 13 is lowered as shown by the chain line in FIG. 9, and the tip of the valve 13 is moved to the gate 5
The gate 5 is closed by fitting it to. The valve 13 is guided by the guide bush 8 while being restricted in the radial direction, and is aligned with the gate 5. Then, after the resin filled in the cavity 3 is solidified, the fixed-side mold member 1 and the movable-side mold member 2 are opened to take out a product which is the solidified resin in the cavity 3.

[0005]

In the conventional valve gate type mold, the valve 13 is moved by the vertical movement of the valve 13.
Since the lower front end of 13 is removably fitted into the gate 5 to open and close the gate 5, it is important to center the valve 13 with the gate 5 when opening and closing the gate 5. In the conventional device that opens and closes the gate 5 by vertically moving the valve 13 of this type, the guide bush 8 holds the valve 13 so that the shaft core is aligned with the guide bush 8 that holds the valve 13. Since the gate and the gate 5 are located apart from each other, the misalignment between the valve 13 and the gate 5 is likely to occur, and the resin is always kept in the molten state by the heater 6 in the valve casing 7. Even if the valve 13 is deformed by heat from the resin, misalignment between the valve 13 and the gate 5 is likely to occur. When such misalignment occurs, the valve 13 and the gate 5 rub against each other when the valve 13 moves up and down, and the sliding portions thereof wear, so that the gate 5 can be completely blocked by the valve 13. However, there was a problem that flash could occur on the gate mark of the molded product. Furthermore, in order to smoothly operate the valve 13 that opens and closes the gate 5 in the vertical direction,
A certain amount of clearance is required between 13 and the guide bush 8 that slidably holds the valve 13. That is, if there is no clearance between the valve 13 and the guide bush 8, the valve 13 is tightly fitted to the guide bush 8, and the valve 13 is caught by the guide bush 8 and the movement of the valve 13 becomes poor. Therefore, there is a problem that a clearance is created between the valve 13 and the guide bush 8 due to the clearance, and the molten resin in the valve casing 7 leaks from this clearance.

The present invention solves such a problem and
An object of the present invention is to provide a valve gate device for an injection molding die, which can prevent burrs from being generated on a gate mark of a molded product and can prevent resin leakage.

[0007]

The present invention is intended to achieve the above object, and a valve gate device for an injection molding die according to the invention of claim 1 forms a cavity inside when a mold is clamped. A plurality of movable mold members, a gate provided in a fixed mold member among these mold members and opening to the cavity, and a gate passage for supplying molten resin to the cavity through the gate. In a valve gate device of an injection molding die provided with a valve for opening and closing the gate provided in the gate passage, the valve is provided rotatably in a horizontal direction, and the valve has a closing portion for closing the gate. And a resin passage that connects the gate passage and the gate by rotation of the valve.

Further, in the valve gate device of the injection molding die according to the invention of claim 2, the closing portion of the valve is provided with the cutting portion for cutting the gate mark of the resin filled in the cavity. .

[0009]

According to the first aspect of the present invention, when the resin passage of the valve is aligned with the gate and the gate is opened during the injection process, the resin supplied from the gate passage passes through the resin passage and enters the cavity from the gate. To be filled. When the valve is rotated after the injection process, the resin passage is separated from the gate and the gate is closed by the closing part, so the gate is cut reliably and burrs are prevented from forming on the gate mark of the molded product. To be done.

According to the second aspect of the present invention, the gate trace of the molded product can be scraped off cleanly at the cutting portion while the gate is closed at the closing portion by the rotation of the valve.

[0011]

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. 1 to 4 show a first embodiment of the present invention, in which 21 is a fixed-side mold member and 22 is a movable-side mold member. It moves in the direction and opens and closes to form a product-shaped cavity 23 inside during mold clamping. The fixed-side mold member 21 is attached to a fixed-side attachment plate 27 attached to a fixed-side platen of the injection molding machine via receiving plates 24 and 25 and a spacer block 26. On the other hand, although not shown, the movable-side mold member 22 is attached to a movable-side mounting plate attached to a movable-side platen of the injection molding machine via a receiving plate and a spacer block. A manifold 29 containing a heater 28 is provided between the receiving plate 24, the spacer block 26 and the fixed side mounting plate 27. Inside the manifold 29, the fixed side mounting plate
Spool 30 in spool bush 30 embedded and fixed in 27 and connected to the nozzle (not shown) of the injection molding machine body
A runner 31 communicating with A is formed. The stationary mold member 21 has a cavity member 32 that forms the cavity 23, and a gate bush 33 is embedded and fixed in the cavity member 32 so as to face the cavity 23. The gate bush 33 has a gate 34 that opens toward the cavity 23 on the lower end side with the vertical direction in the drawing as the axial direction. Further, on the outer peripheral surface of the gate bush 33, a pair of O-rings for sealing is provided between the gate bush 24 and the cavity member 23 with a cooling passage 35A communicating with a cooling passage 35 formed in the cavity member 32 interposed therebetween. 36,3
7 are provided. Also, a receiving plate for the fixed-side mold member 21.
24 and 25 have a valve casing 39 with a built-in heater 38
Is fixed in a penetrating state. This valve casing 39
The lower end of the figure is coaxially fitted and fixed in the gate bush 33. Further, a guide bush 41 holding a pin-shaped valve 40 is coaxially fitted and fixed to the upper portion of the inner peripheral surface of the valve casing 39 in the drawing, and the valve bush is attached to the lower portion of the gate bush 33 in the drawing.
A recess 33A is formed which fits with the lower end of the valve 40 in the figure, and the guide bush 41 and the recess 33A hold the valve 40 rotatably in the horizontal direction in the figure. The gap between the valve 40 and the inner peripheral surface of the valve casing 39 serves as a gate passage 42, and the gate passage 42 is formed by the manifold passage 42A provided on the upper side of the valve casing 39 in the figure to form the manifold. It is connected to 29 runners 31. Further, the gate 34 is provided at the inner bottom of the recess 42 at a position eccentric from the rotation center of the valve 40. The gate 34 is closed by abutting the illustrated lower end surface of the valve 40 fitted in the recess 42 of the gate bush 33 against the inner bottom of the recess 42,
The lower end surface of 40 serves as a closing portion 43 of the gate 34. Further, a groove-shaped resin passage 44 is formed in the axial direction on the outer peripheral surface of the valve 40, and the lower end portion of the resin passage 44 in the drawing is the valve 40.
Has an opening at the lower end surface thereof, and its upper end in the drawing extends higher than the inner peripheral surface of the recess 42 and communicates with the gate passage 42. Then, the valve 40 is rotated 90 degrees in the horizontal direction in the drawing so that the lower opening side of the resin passage 44 of the valve 40 is moved to the gate 34.
By matching with, the gate 34 and the gate passage 42 are communicated with each other through the resin passage 44. Further, the illustrated upper side of the valve 40 penetrates the manifold 29 and the fixed side mounting plate 27, and is arranged on the upper side of the valve 40 protruding from the fixed side mounting plate 27 in the axial direction of the valve 40. The contact plates 45 are assembled and fixed so as to be orthogonal to each other. Then, as shown in FIG.
Is connected to a fluid pressure (hydraulic pressure or pneumatic pressure) cylinder device 46 as a driving device for rotating in the horizontal direction in the drawing. Further, on the rear side of the fixed side mounting plate 27, the valve 40
A regulation plate 45A for regulating the rotation range of the regulation plate 45A is fixed, and when the contact plate 45 is rotated around the valve 40, an arc locus of the left and right outer edge portions of the regulation plate 45A is fixed to the regulation plate 45A. Approximately 1/4 arc-shaped openings 48, 49 having a slightly larger diameter arc portion 47 and vertical portions 48A, 49A and horizontal portions 48B, 48B connected to the arc portion 47 are formed. 48, 49 vertical parts 48A, 49A and horizontal parts 48B, 49B
The valve 40 can be freely rotated within a range of 90 degrees by attaching a contact plate 45 to the.

Next, the operation of the above configuration will be described. At the time of molding, the fixed mold member 21 and the movable mold member 22 are clamped. Further, as shown by the solid line in FIG. 4, both side portions of the contact plate 45 fixed to the valve 40 abut on the horizontal portions 48B and 49B of the openings 48 and 49 with the valve 40 as the center. In this state, as shown by the solid line in FIG. 3, the resin passage 44 formed at the lower end of the valve 40 in the drawing coincides with the gate 34, and the gate 34 and the gate passage 42 communicate with each other through the resin passage 44. The gate 34 is open. Then, the molten resin is injected from the nozzle of the injection molding machine. This resin passes from the sprue 30A, through the runner 31, the manifold passage 42A, and the gate passage 42 in the valve casing 39, through the resin passage 44 of the valve 40,
The cavity 34 is filled from the opened gate 34. After this filling is completed, as shown by the chain line in FIG. 3, the cylinder-device 46 moves the contact plate 45 in the clockwise direction (in FIG. 4, arrow a).
Direction) and rotate both sides of the plate 45 into the openings 48, 49.
When it hits the vertical parts 48A and 49A of the
Rotate 0 degrees to stop rotation. As the valve 40 rotates, the resin passage 44 of the valve 40 separates from the gate 34 as shown by the chain line in FIG. 3, and the gate 34 is closed at the lower end of the valve 40 that abuts the inner bottom of the recess 33A. Blocked by part 43. Then, after the resin in the cavity 23 is cooled and solidified, the fixed side mold member 21 and the movable side mold member 22 are opened.

As described above, the present invention does not open and close the gate by removably fitting the lower end of the valve to the gate by vertically moving the valve, but by rotating the valve 40, the resin passage of the valve 40 is rotated. Since the gate 44 is opened and closed by connecting and disconnecting 44 and the gate 34, the valve 40 and the gate 34
The centering with respect to is not necessary, and the closing of the valve 40 by the rotation of the valve 40, that is, the lower end surface of the valve 40 closes the gate 34, so that the gate 34 can be closed reliably. Therefore, even if molding is repeated many times, burrs are less likely to occur in the gate mark of the molded product. Further, since the valve 40 is rotatably held by the guide bush 41, even if the clearance between the guide bush 41 and the valve 40 is set smaller than when the valve is slidably guided vertically, Since it has little influence on the operation of the valve 40 in the rotating direction, it is possible to suppress resin leakage from the gap between the guide bush 41 and the valve 40.

FIGS. 5 and 6 show a second embodiment of the present invention. The parts common to those of the first embodiment are designated by the same reference numerals, the description thereof will be omitted, and the different points will be mainly described. To do. In this example, the lower end of the valve 40 in the drawing is extended to the lower side of the cavity 23 in the drawing so that the side surface of the valve 40 directly faces the cavity 23. Further, the lower end side of the valve 40 is fitted into a recess 50 formed in the fixed-side mold member 21, and a gate 51 opening to the cavity 23 side is formed in the recess 50.
Is formed. Further, the lower end of the valve 40 communicates with the gate 51 on the outer peripheral surface of the lower end of the valve shown in the figure, and the upper end side of the figure shows the gate passage.
A semicircular resin passage 52 communicating with 42 is formed, and the outer peripheral surface of the valve 40 serves as a closing portion 53 that closes the gate 51.

In molding, the resin passage 52 of the valve 40 and the gate 51 are aligned with each other and the molten resin is injected from the nozzle of the injection molding machine. The resin passes through the gate passage 42 and the resin passage 52 and is filled into the cavity 23 from the opened gate 51. After this filling is completed, as shown by the chain line in FIG. 6, if the valve 40 is rotated by approximately 90 degrees, the resin passage 52 of the valve 40 and the gate 51 are separated by the rotation of the valve 40, and the valve 40 is rotated. With the closed portion 53 formed on the outer peripheral surface biting from the gate 51 to the cavity 23 side,
Is blocked. Therefore, as in the first embodiment described above, the gate is surely closed by surely closing the gate 51, and burrs are less likely to occur in the gate mark of the molded product.

FIGS. 7 and 8 show a third embodiment of the present invention. The parts common to the respective embodiments are designated by the same reference numerals, the description thereof will be omitted, and the different points will be mainly described. . In this example, the resin passage 55 formed of a spiral groove is formed on the outer peripheral surface of the valve 40. Similar to the first embodiment, the resin passage 55 opens at the lower end surface of the valve 40 in the drawing, and the gate 34 is eccentric from the center of rotation of the valve 40 in the recess 33A formed in the gate bush 33 corresponding to the lower opening thereof. It is provided in the open position. Then, a closing portion 56 that closes the gate 34 is formed on the lower end surface of the valve 40, and in this example, two cutting blades 57 and 58 that serve as cutting portions as sharp edges of the closing portion 56.
To form. That is, in the third embodiment, the valve
With the rotation of 40, the resin passage 55 of the valve 40 and the gate 34 are communicated with each other and shut off, and the gate 34 is opened and closed. Therefore, as in each of the above embodiments, burrs are less likely to occur in the gate mark of the molded product, and While closing the gate 34 with the closing portion 56 of the valve 40,
At the same time, the rotation of the valve 40 allows the cutting blades 57 and 58 to cleanly remove the gate marks of the molded product filled in the cavity 23.

The embodiment of the present invention has been described in detail above.
The present invention is not limited to the above-mentioned embodiments, but various modifications can be made. For example, in each of the above-described embodiments, the example in which the valve is rotationally driven by the fluid pressure cylinder device is shown, but the valve may be rotationally driven by a motor. Further, the structure for restricting the rotation of the valve within the range of 90 degrees may be appropriately set. Further, in each of the embodiments, the example in which the groove-shaped resin passage is formed on the outer peripheral surface of the valve has been shown, but the through hole-shaped resin passage opening to the outer peripheral surface and the lower end surface of the valve is formed to form the gate and the gate passage. May be in communication. Further, the basic structure of the injection molding machine, the heater structure of the valve, etc. may be set appropriately.

[0018]

According to the invention of claim 1, since the valve is provided with the closing portion for closing the gate and the resin passage for connecting the gate passage and the gate by the rotation of the valve, when closing the gate,
By rotating the valve, the gate and the closed portion can be surely aligned with each other to reliably cut the gate, and burrs are less likely to occur in the gate mark of the molded product.

Further, according to the invention of claim 2, since the cutting portion for cutting the trace of the gate of the resin filled in the cavity is provided at the closing portion of the valve, the gate is closed at the same time by the rotation of the valve. The cutting part can cleanly remove the gate mark of the molded product.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a valve gate type mold showing a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of the vicinity of the gate.

3 is a sectional view taken along line AA of FIG. 2 above.

FIG. 4 is a plan view showing the vicinity of the above cylinder device.

FIG. 5 is an enlarged cross-sectional view of the vicinity of a gate showing a second embodiment of the present invention.

6 is a sectional view taken along line BB of FIG. 5 above.

FIG. 7 is an enlarged cross-sectional view showing the vicinity of a gate according to a third embodiment of the present invention.

8 is a sectional view taken along line CC of FIG.

FIG. 9 is a sectional view of the vicinity of a conventional valve casing.

[Explanation of symbols]

 21 Fixed mold member (mold member) 22 Movable mold member (mold member) 23 Cavity 34, 51 Gate 40 Valve 42 Gate passage 43, 53, 56 Closure 44, 52, 55 Resin passage 57, 58 Cutting blade (cutting part)

Claims (2)

[Claims] 1. A plurality of mutually movable mold members that form a cavity inside during mold clamping, a gate provided in a fixed mold member of these mold members and opening to the cavity, and In a valve gate device of an injection molding die including a gate passage for supplying a molten resin to the cavity through a gate and a valve provided in the gate passage for opening and closing the gate, the valve is provided in a horizontal direction. A valve gate device for an injection molding die, which is rotatably provided, and in which this valve is provided with a closing portion that closes the gate and a resin passage that connects the gate passage and the gate by rotation of the valve. . 2. The valve gate device for an injection molding die according to claim 1, wherein a cut portion for cutting a gate mark of the resin filled in the cavity is provided in the closed portion of the valve.