JPH05104581A - Valve gate type mold assembly - Google Patents

Abstract

PURPOSE:To form the gate trace of a molded form in a singlet line, and to prevent the abrasion of a gate due to the sliding of a valve. CONSTITUTION:A gate insert 37 composed of the quality of material, which is harder than a cavity-surface forming member 34 and has excellent abrasion resistance, is buried into the cavity-surface forming member 34 under the state, in which the gate insert is not exposed to a cavity surface. A first gate hole 59 formed to the gate insert 37 and a second gate hole 60 formed to the cavity- surface forming member 34 are continued in a coaxial manner, thus constituting a gate 38. Consequently, the first gate hole 59 in the rigid gate insert 37 is difficult to be worn away originally. Since a valve 39 is aligned with the gate 38 by fitting to the first gate 59, the second gate hole 60 in the soft cavity- surface forming member 34 is also difficult to be worn away. A soft material is used as the quality of material of the cavity-surface forming member 34, thus easily machining a cavity surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve gate type mold apparatus used for resin injection molding.

[0002]

2. Description of the Related Art A valve gate type mold device used for injection molding of resin is a device in which a gate opens and closes a cavity formed between a plurality of mold members at the time of mold clamping by a valve. That is, during the injection process, the gate is opened, and the resin is poured into the cavity from this gate, and after the injection process, the valve is closed to keep the resin on the hot runner side in a molten state while maintaining the resin inside the cavity. The resin is designed to be cooled and solidified. Here, an example of a conventional valve gate mold apparatus will be described with reference to FIG. FIG. 3 shows the gate 2 portion of the fixed-side mold member 1. Cavity 3
A gate bush 5 made of a hard material such as HSS is embedded and fixed in a cavity surface forming member 4 that forms the surface (hereinafter, referred to as a cavity surface). The gate bush 5 is exposed in a state in which the convex portion 6 formed at the tip portion thereof slightly projects to the cavity surface of the cavity surface forming member 4. That is, the tip portion of the convex portion 6 of the gate bush 5 forms a part of the cavity surface. The gate 2 having an axial direction in the vertical direction in the drawing is formed through the convex portion 6 of the gate bush 5. Further, a tubular valve casing 8 containing a heater 7 is fitted and fixed in the gate bush 5. Inside the valve casing 8, there is a pin-shaped valve 9 made of HSS or the like that moves up and down to open and close the gate 2. The valve 9 is supported in the valve casing 8 by a valve holder 10 so as to be movable only in the axial direction.
Is fixed by being pressed from below in the figure. The opening hole 12 at the tip of the cap 11 is continuous with the gate 2 but has a diameter slightly larger than that of the gate 2. With this configuration, when the valve 9 is raised as shown in the solid line, the gate 2 is opened, and when the valve 9 is lowered as shown by the chain line, the valve 9 is opened.
Is slidingly fitted into the gate 2 to close the gate 2. However, in such a conventional valve gate mold apparatus, since the gate bush 5 having the gate 2 formed at the tip is exposed at the cavity surface of the cavity surface forming member 4, a gate mark 13 that can be formed into a molded product is obtained.
Has a double line shape as shown in FIG. 4, and there is a problem that the appearance of the molded product is impaired.

Therefore, in order to solve this problem, FIG.
A valve gate type mold device as shown in FIG. In this mold apparatus, the gate bush 5 is not exposed on the cavity surface of the cavity surface forming member 4, and the gate 16 on which the valve 9 is slidably fitted is directly formed on the cavity surface forming member 4. I am collecting. According to this structure, the gate mark 17 formed on the molded product is 1 as shown in FIG.
It becomes a heavy line shape and the appearance of the molded product is improved. By the way, in order to facilitate the processing of the cavity surface, it is preferable that the material of the cavity surface forming member 4 is soft. In fact, for example, when molding a transparent storage case of a compact disc, the material of the cavity surface forming member 4 is made soft in order to enhance the mirror surface property of the surface of the molded product. However, when the gate 16 in which the valve 9 is slidably fitted is formed in the soft cavity surface forming member 4 itself, the misalignment between the gate 16 and the valve 9 causes
The gate 16 is easily worn by the sliding of the valve 9. As a result, when molding is repeated, an unacceptable gap is formed between the inner peripheral surface of the gate 16 and the outer peripheral surface of the valve 9 at a relatively early stage, and this gap causes flash on the gate trace 17 of the molded product. It becomes like this. On the other hand, in the valve gate mold apparatus shown in FIG. 3, the cavity surface forming member 4
Even if the material is soft, by making the material of the gate bush 5 hard, it is possible to make the gate 2 less likely to wear. However, as described above, there is a problem that the gate trace 13 becomes a double line.

[0004]

As described above, in the conventional valve gate type mold device in which the gate bush having the gate is exposed on the cavity surface of the cavity surface forming member, the gate mark of the molded product is doubled. There is a problem in that it becomes linear and the appearance of the molded product is impaired. On the other hand, without exposing the gate bush to the cavity surface of the cavity surface forming member,
In the valve gate type mold device in which the gate is directly formed on the cavity surface forming member, there is a problem that the gate is easily worn due to sliding of the valve.

The present invention is intended to solve such a problem, and provides a valve gate type mold device which can make a gate mark of a molded product into a single line shape and is excellent in wear resistance of the gate. The purpose is to do.

[0006]

In order to achieve the above object, the present invention provides a plurality of mutually movable mold members that form a cavity inside during mold clamping, and a fixed side of these mold members. A gate provided on the mold member and opening to the cavity; and a valve provided on the fixed-side mold member movably in the axial direction of the gate to open and close the gate, the fixed-side mold member, A cavity surface forming member that forms the surface of the cavity, and a gate insert that is made of a material that is harder and has better wear resistance than the cavity surface forming member and that is embedded in the cavity surface forming member without being exposed to the cavity surface. And a gate, the gate
A first gate hole formed in the gate insert and into which the valve is slidably fitted, and a first gate hole formed in the cavity surface forming member and coaxially continuous with the first gate hole, the valve slides. And a second gate hole that is movably fitted.

[0007]

In the valve gate type mold apparatus of the present invention,
With a plurality of mold members clamped and the gate open, resin is poured from this gate into the cavity formed between the mold members to fill it, and then the valve is moved to fit the gate. This closes this gate. By the way, in this gate, the first gate hole formed in the gate nest and the second gate hole formed in the cavity surface forming member are coaxially continuous, but the gate nest is Since the first gate hole is made of a material that is harder than the surface forming member and has excellent wear resistance, the first gate hole is less likely to wear even when the valve slides in the fitted state. In addition, since the valve is aligned with the gate by fitting the valve into the first gate hole, the second gate hole formed in the softer cavity surface forming member also slides in the fitted state of the valve. Is hard to wear. Since the gate insert is embedded in the cavity surface forming member in a state where it is not exposed to the surface of the cavity, the number of gate traces formed on the molded product is 1
It becomes a double line.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the valve gate mold apparatus of the present invention will be described below with reference to FIGS.
The valve gate type mold device of this embodiment is for molding a transparent storage case for a compact disc. In FIG. 2, 21 is a fixed-side mold member, 22 is a movable-side mold member, and both mold members 21 and 22 move in the vertical direction in the drawing to open and close. A slide core 23, which is a mold member, is attached to the movable mold member 22 so as to be movable in the horizontal direction in the drawing. A cavity 24 is formed inside the fixed mold member 21, the movable mold member 22 and the slide core 23 which are clamped. It should be noted that the cavity 24
Are formed in plural. The fixed side mold member 21 is a receiving plate 2
It is attached to the fixed side mounting plate 28 for mounting on the fixed side platen of the injection molding machine body via 5, 26 and the spacer block 27. And the receiving plate
A manifold 30 including a heater 29 is provided between the 26, the spacer block 27, and the fixed-side mounting plate 28. A sprue bush 31 to which the nozzle of the main body of the injection molding machine is connected is embedded and fixed in the fixed side mounting plate 28, and the inside of the sprue bush 31 is a sprue.
It is 32. A runner 33 communicating with the sprue 32 is formed in the manifold 30.
In the fixed-side mold member 21, a gate bush 35 is embedded and fixed in a cavity surface forming member 34 forming a cavity surface so as to correspond to each cavity 24.
At the same time, a tubular valve casing 36, whose lower end in the figure is fitted and fixed in each gate bush 35, is embedded and fixed in the receiving plates 25 and 26, and inside the valve casing 36 is the manifold. 30 runners 33 are in communication with each other. Further, a tapered tubular gate insert 37 fitted to the outer peripheral side of the lower end of each valve casing 36 in the drawing is provided with a cavity surface forming member 34.
It is embedded and fixed in. Then, from the lower end in the figure of each gate insert 37 to the cavity surface forming member 34,
A gate 38 is formed which opens into the cavity 24 and whose axial direction is the vertical direction in the drawing. In this way, the nozzle of the injection molding machine body communicates with the gate 38. A pin-shaped valve 39 that opens and closes the gate 38 is supported in each of the valve casings 36 so as to be vertically movable in the drawing. These valves 39 penetrate the manifold 30 and are respectively connected to hydraulic or pneumatic cylinder devices 40 provided on the fixed side mounting plate 28, and are driven by these cylinder devices 40. The movable-side mold member 22 is attached to a movable-side mounting plate 44 for mounting on the movable-side platen of the injection molding machine body via the receiving plates 41 and 42 and the spacer block 43. Further, a protruding plate 45 is supported between the receiving plate 42, the spacer block 43, and the movable side mounting plate 44 so as to be movable in the vertical direction in the drawing relative to these, and the protruding plate 45 is attached to the protruding plate 45. Has a protruding pin 46 fixed to protrude the molded product when the mold is opened. Further, the slide core 23 is for forming a bearing hole or the like of a storage case of a compact disc, which is a molded product, and an angular pin 47 fixed to the fixed side mold member 21 slidably penetrates. By doing so, in conjunction with opening and closing of the fixed-side mold member 21 and the movable-side mold member 22, the movable-side mold member 22 moves in the horizontal direction in the drawing.

Next, the structure of the gate 38 portion will be described in more detail with reference to FIG. The valve casing 36 is provided with a heater 52 on the outer peripheral side of the inner cylinder 51, the heater 52 is covered with a heater cover 53 from the outer peripheral side, and further, an outer cylinder is provided on the outer peripheral side of the heater cover 53. 54 is provided. Also,
A valve holder 55, which holds the valve 39 slidably only in the axial direction thereof, is fitted in the inner cylinder 51. The valve holder 55 is screwed into the inner cylinder 51 from the lower side in the drawing. The cap 56 is pressed and fixed. An opening hole 58 having a diameter slightly larger than that of the closed portion 57 at the lower end of the valve 39 is provided at the lower end of the cap 56. The gate insert 37 is sandwiched and fixed by the cavity surface forming member 34 and the gate bush 35, but is not exposed at the cavity surface of the cavity surface forming member 34. And, while the cavity surface forming member 34 is made of a relatively soft material such as HRC53 to 55, the gate insert 37 is made of a material such as powder HSS (HAP-50) which is harder and has excellent wear resistance. It consists of The valve 39
Is made of high speed steel. Then, the first gate hole 59 into which the closing portion 57 of the valve 39 coaxially positioned below the opening hole 58 of the cap 56 is slidably fitted to the lower end portion of the gate insert 37 shown in the figure. And a second gate hole 60, which is located below the first gate hole 59 in the drawing, and in which the closing portion 57 of the valve 39 is slidably fitted to the cavity surface forming member 34. The opening is formed. That is, both the first gate hole 59 and the second gate hole 60 have the same diameter as the closing portion 57 of the valve 39 and are coaxially continuous with each other, and the gate 38
Are configured.

Next, the operation of the above configuration will be described. During molding, when the cylinder device 40 is driven and the cylinder 39 is driven, as shown by the solid line in FIG. 1, the valve 39 is raised to open the gate 38 and melted from the nozzle of the injection molding machine body. The injected resin is injected.
This resin is used for sprue 32 and runner 33 of manifold 30.
And, through the inside of the inner cylinder 51 of the valve casing 36, it flows into the cavity 24 from the opened gate 38 and is filled in the cavity 24. After completion of this filling, the cylinder device 40 is driven so that the valve 39 descends and fits into the gate 38 as shown by the chain line in FIG.
To block. The tip of the closed portion 57 of the valve 39 slightly projects into the cavity 24. Then, after the resin in the cavity 24 is sufficiently cooled and solidified, the fixed side mold member 21 and the movable side mold member 22 are opened, and in conjunction with this,
The slide core 23 separates from the molded product, and the molded product is ejected by the ejection pin 46 and released.

As mentioned above, the gate 38 is the gate insert 37.
The first gate hole 59 formed in the cavity and the second gate hole 60 formed in the cavity surface forming member 34 located closer to the cavity 24 than the first hole 59 are coaxially continuous. Since the insert 37 is made of a hard material having excellent wear resistance such as powder HSS, the first gate hole 59 is
Even if the closed portion 57 of the valve 39 slides in the fitted state, it is hard to wear. On the other hand, the softer cavity surface forming member 34 is
Although the material is likely to be worn, it is softer because the valve 39 is aligned with the gate 38 by being fitted into the first gate hole 59 prior to being fitted into the second gate hole 60. The second gate hole 60 formed in the cavity surface forming member 34 is also less likely to wear even if the closed portion 57 of the valve 39 slides in the fitted state. And, since the gate 38 is less likely to wear in this way, even if molding is repeated many times, a gap is unlikely to be formed between the inner peripheral surface of the gate 38 and the outer peripheral surface of the closed portion 57 of the valve 39, and therefore, Prevents burrs from forming on the gate marks of molded products. Further, since the material of the cavity surface forming member 34 can be made soft while preventing the wear of the gate 38 as described above, the processing of the cavity surface is facilitated, and the mirror surface of the transparent storage case of the compact disc can be improved. To be enhanced. Further, since the gate insert 37 is embedded in the cavity surface forming member 34 in a state where it is not exposed to the cavity surface, the gate mark formed on the molded product has a single line shape as shown in FIG. become. As a result, the appearance of the molded product is improved as compared with the case of the conventional valve gate mold apparatus in which the gate bush 5 having the gate 2 formed is exposed on the cavity surface of the cavity surface forming member 4.

The present invention is not limited to the above embodiment, but various modifications can be made. For example,
In the above embodiment, the molded product is a transparent storage case of a compact disc, but the present invention can be applied to other molded products. Further, the sectional shapes of the valve and the gate are not limited to the circular shape, and may be a rectangular shape or the like. Furthermore, the material of each member is not limited to that of the above embodiment. For example, the material of the gate insert is not limited to powder high-speed steel, but may be any material that is hard and has excellent wear resistance.

[0013]

According to the present invention, a gate insert made of a material harder than the cavity surface forming member and having excellent wear resistance is embedded in the cavity surface forming member without exposing the cavity surface, A first gate hole formed in the gate insert and into which the valve is slidably fitted; and a valve that is formed in the cavity surface forming member and is coaxially continuous with the first gate hole so that the valve is slidably fitted. Since the first gate hole formed by the hard material is hard to wear even when the valve slides in the fitted state, the second gate hole is fitted to the first gate hole. Since the valve is aligned with the gate by fitting, the second gate hole formed in the soft material is also less likely to wear, and thus the gate is less likely to wear, so that molding is repeated many times. Also, Over preparative inner peripheral surface and a gap is hardly generated between the outer peripheral surface of the valve, possible to prevent the burr occurs in the gate marks of the molded article. Further, although the gate surface can be prevented from being worn in this way, the material of the cavity surface forming member can be made soft, so that the processing of the cavity surface becomes easy. Furthermore, since the gate insert is embedded in the cavity surface forming member in a state where it is not exposed to the cavity surface, the gate mark formed on the molded product becomes a single line,
The appearance of the molded product is improved.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a gate portion showing an embodiment of a valve gate type mold device of the present invention.

FIG. 2 is a sectional view of the entire same as above.

FIG. 3 is an enlarged cross-sectional view of a gate portion showing an example of a conventional valve gate mold apparatus.

FIG. 4 is a plan view showing gate marks of a molded product molded by the same as above.

FIG. 5 is an enlarged cross-sectional view of a gate portion showing another example of the conventional valve gate mold apparatus.

FIG. 6 is a plan view showing a gate mark of a molded product molded by the same as above.

[Explanation of symbols]

 21 Fixed-side mold member 22 Movable-side mold member (mold member) 23 Slide core (mold member) 24 Cavity 34 Cavity surface forming member 37 Gate insert 38 Gate 39 Valve 59 First gate hole 60 Second Gate hole

Claims (1)

[Claims] 1. A plurality of mutually movable mold members that form a cavity inside during mold clamping, a gate provided on a fixed mold member of these mold members and opening to the cavity, and the fixed member. The side mold member is provided with a valve that is movable in the axial direction of the gate and that opens and closes the gate. The fixed mold member includes a cavity surface forming member that forms a surface of the cavity, and a cavity surface forming member. The cavity surface forming member is made of a material that is harder than the forming member and is excellent in wear resistance, and the gate insert is embedded in the cavity surface so as not to be exposed to the surface of the cavity.
A first gate hole formed in the gate insert and into which the valve is slidably fitted, and a first gate hole formed in the cavity surface forming member and coaxially continuous with the first gate hole, the valve slides. A valve gate type mold device comprising a second gate hole that is movably fitted.