JPH0655586A - Injection molding die - Google Patents

Abstract

PURPOSE:To provide an injection molding die capable of positively removing a sprue from the front end of a gate cutter. CONSTITUTION:A recessed section 62 is formed at the front end section of the ejector-pin inserting hole 61 of a gate cutter 55, and a sprue-puller hole 69 as a space including the recessed section 62 can be formed when an ejector pin 63 is positioned at a relatively retreated location. A sprue-puller section 70a solidified in the sprue-puller hole 69 is engaged with the recessed section 62, but an engaging section is deformed by the pushing of the ejector pin 63, and a sprue 70 is detached from the front end of the gate cutter 55. The pushing of the sprue 70 by the ejector pin 63 is conducted along the axial direction of the shaft-shaped section 70b of the sprue 70, and there is no section that the sprue 70 is fixed to the gate cutter 55 with the exception of the engaging section, thus dismantling only the shaft-shaped section 70 by the pushing of the ejector pin 63 even when the sprue 70 is not solidified completely, then preventing remaining at the front end of the gate cutter 55 in a cuppy section 70.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding die which is used by assembling a disk such as a laser disk or a compact disk in an injection molding machine for a disk. Regarding the shape.

[0002]

2. Description of the Related Art Conventionally, various injection molding dies used by being assembled in a disk injection molding machine for molding a laser disk, a compact disk or the like have been known. In these injection molds, it is necessary to remove the sprue in which a part of the injected molten resin is solidified in the injection hole. For this reason, for example, as shown in FIG.
The sprue 106, which is solidified by partially cutting into the groove 104 provided along the outer periphery of the tip end of No. 2, is attached to the tip end of the gate cutter 102 when the mold is opened, and is taken out from the injection hole. The sprue 106 that is being ejected is ejected by the ejector pin 108 to be detached and removed from the injection molding die.

[0003]

However, in the gate cutter 102 having the shape as shown in FIG. 3, the groove 104 depends on the gate cutting timing, the resin temperature, the cooling time, and the like.
And the cup-shaped portion 106a of the sprue 106 may be firmly joined. When this happens, the sprue 10
The cup-shaped portion 106a of No. 6 becomes difficult to separate from the gate cutter 102, and when ejected by the ejector pin 108, only the shaft-shaped portion 106b of the sprue 106 may be separated and ejected [see FIG. 3 (b)]. . Reducing the cooling and solidifying time of the sprue 106 is effective for shortening the time required for one injection molding and increasing the cycle. However, if the ejector pin 108 is used to project the sprue 106 in a state where the sprue 106 is not sufficiently solidified, the above-described problem tends to occur, which is one of the reasons for hindering cycle up.

A normal sprue take-out machine has a structure in which the shaft-like portion 106b of the sprue 106 is held and the sprue 106 is taken out from the mold. When the pick-up is performed while holding the shaft-like portion, it is determined that the entire sprue 106 has been normally removed. Because
While the cup-shaped portion 106a of the sprue 106 is attached to the tip of the gate cutter 102, the mold may be closed to start the next injection molding. If the mold is closed in such a state, the mold may be damaged, which has been a problem.

Therefore, it is an object of the present invention to provide an injection molding die capable of reliably removing the sprue from the tip of the gate cutter even when the sprue is not sufficiently solidified.

[0006]

To achieve the above object, an injection mold of the present invention comprises a fixed mold fixed to a fixed plate of an injection molding machine and a movable mold fixed to a movable plate. The two molds have a mirror surface plate that forms a disk-shaped cavity between the joint surfaces when the molds are closed, and the molten resin can pass through the central surface of the mirror plate of the fixed mold. An injection hole, a gate cutter arranged concentrically with the mirror surface plate of the movable mold, capable of moving forward and backward, and a forward end is fitted into the injection hole when the gate is cut, and the gate cutter is attached to the gate cutter. In an injection molding die provided with an ejector pin insertion hole formed concentrically and opening at the tip end surface of the gate cutter, and an ejector pin inserted through the ejector pin insertion hole so as to be able to move forward and backward, the ejector at the time of cutting the gate. The tip surface of the injection hole side of the ejector pin is housed in the ejector pin insertion hole to form a sprue puller hole in a columnar space by the tip surface of the ejector pin and the ejector pin insertion hole, and the ejector pin insertion hole An injection-molding die, characterized in that a recess is provided in an inner hole at an end forming the sprue puller hole.

[0007]

In the injection mold of the above construction, the fixed mold and the movable mold are fixed to the fixed plate and the movable plate of the injection molding machine, respectively, prior to the injection molding. Further, a stamper corresponding to the disk to be molded is attached to one mirror surface plate.

First, the movable plate is moved forward to move the movable mold toward the fixed mold, the mold is closed, and the mold is clamped with a predetermined pressure. At this time, a cavity is formed between the fixed-side and movable-side mirror surfaces. The gate cutter is in the retracted position. Further, the ejector pin that is inserted into the ejector pin insertion hole of the gate cutter is also in the retracted position.

Then, the molten resin is injected into the cavity through the injection hole. The molten resin fills the inside of the cavity. Furthermore, the injection of the molten resin is continued until the predetermined injection amount is reached, and the inside of the cavity is densely filled with the molten resin. Then, the gate cutter advances so as to pass through the cavity, and the tip end is fitted into the injection hole to cut the gate. At this time, since the ejector pin is held at the retracted position, the relative position between the ejector pin insertion hole of the gate cutter and the ejector pin changes. Due to the change in the relative position between the gate cutter and the ejector pin as the gate cutter moves forward, the ejector pin is retracted relative to the ejector pin insertion hole, and the ejector pin insertion hole has an ejector hole at the end on the injection hole side. Columnar space part where the pin is not inserted,
That is, a sprue puller hole is formed. Further, as the gate cutter advances, molten resin near the center of the cavity is removed, but this portion becomes the center hole of the molded disk.

The injection hole is closed by the gate cut,
The molten resin is prevented from flowing into the cavity, and the injection of the molten resin ends. However, since the injection of the molten resin is continued until the gate cutting is completed, when the sprue puller hole is formed, the molten resin also flows into the sprue hole, so that the inside of the sprue hole is also densely filled with the molten resin. Is filled.

In this state, when a predetermined solidification time has passed, the molten resin solidifies to form a disk. Further, the resin remaining in the injection hole is solidified into sprue, but the resin in the sprue puller hole becomes a rod-shaped sprue puller portion corresponding to the shape of the sprue puller hole. In this sprue puller portion, a convex portion conforming to the shape of the concave portion provided in the sprue puller hole is formed.

Thereafter, the mold is opened for taking out the product disc and the sprue. Since the convex portion of the sprue puller portion and the concave portion of the sprue puller hole are engaged with each other, the sprue is attached to the tip portion of the gate cutter. Therefore, the sprue is separated from the injection hole when the mold is opened, and is in a state of protruding and adhering to the tip of the gate cutter. When the mold is opened, the ejector pin advances to press the end of the sprue puller. The sprue moves along the moving direction of the ejector pin when pressed by the ejector pin. At this time, the convex portion formed on the sprue puller portion is deformed and detached from the concave portion of the sprue puller hole, which does not hinder the movement. Further, the cup-shaped portion of the sprue does not become an obstacle when it is detached from the gate cutter. As a result, the sprue puller portion is pulled out from the sprue puller hole as the ejector pin advances, and the sprue is detached from the tip of the gate cutter. Since the sprue puller portion that holds the sprue at the tip of the gate cutter is pressed by the ejector pin to separate the sprue from the gate cutter, the entire sprue can be accurately separated from the gate cutter. Therefore, even if the sprue is not completely solidified, only the shaft-shaped portion of the sprue does not separate and the cup-shaped portion remains. Therefore, the time for solidifying the sprue can be shortened and the cycle can be increased. At the same time, damage to the mold or the like due to the sprue cup-shaped portion remaining on the tip of the gate cutter is prevented.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, in order to further clarify the present invention, a preferred embodiment will be described with reference to the drawings. As shown in FIG. 1, the injection molding die 1 of this embodiment includes a plurality of stays 3.
It is assembled to an injection molding machine (not shown) via a fixed plate 7 fastened and fixed by a nut 5 and a movable plate 9 slidably mounted along the stay 3.

First, the structure on the fixed platen 7 side will be described. The fixed plate 7 is fixed to the fixed plate 7 by bolts (not shown), the fixed side mirror surface plate 13 connected to the fixed plate 11 and the fixed side locating block 15 arranged outside the fixed side mirror surface plate 13. A fixed mold 17 composed of is attached.

The surface of the fixed-side mirror surface plate 13 opposite to the fixed member 11 is a cavity surface 13a. Further, the fixed side mirror surface plate 13 is provided with a cooling groove 13b so that the fixed side mirror surface plate 13 can be cooled by supplying a coolant. The guide bushing 1 provided with an inner hole 19a that is open at the center of the fixed-side mirror surface plate 13 in the fixed member 11 and the fixed-side mirror plate 13
9 is fitted. The tip end surface of the guide bushing 19 is located substantially on the same plane as the cavity surface 13a.
A sprue bushing 21 that fits inside the guide bushing 19 is fitted on the fixed member 11. A sprue hole 21a is formed in the sprue bushing 21 along the central axis, and the sprue hole 21a and the guide bushing 19 are formed.
The inner hole 19a and the inner hole 19a form an injection hole 23 that serves as a passage for the injected molten resin. The sprue bushing 21 is concentric with the disk center of the fixed-side mirror surface disk 13, and the central axes of both are common.

A substantially spherical nozzle contact surface 25 is formed at the rear end of the sprue bushing 21. Nozzle contact surface 2
A heating cylinder (not shown) having an injection nozzle at its tip is arranged in the arrow X direction of 5. The injection nozzle communicates with the resin reservoir inside the heating cylinder, and is capable of injecting the molten resin supplied from the heating cylinder. When the heating cylinder advances in the direction of the arrow Y, the tip of the injection nozzle can come into close contact with the nozzle contact surface 25. Therefore, the molten resin from the heating cylinder can be injected from the injection hole 23 through the injection nozzle.

Next, the structure on the movable platen 9 side will be described. A first movable member 31, which is connected to the movable plate 9, a second movable member 33, which is connected to the first movable member 31, and a movable side mirror surface plate 35, which is connected to the second movable member 35, are fixed to the movable plate 9 by bolts (not shown). Also, a movable mold 39 including a movable locating block 37 arranged outside the movable mirror surface plate 35 is attached.

The movable side mirror surface plate 35 is arranged so that the center axis of the disk is common to that of the fixed side mirror surface plate 13. The surface of the movable mirror surface plate 35 on the fixed mirror surface plate 13 side is a cavity surface 35a. In addition, the movable mirror surface plate 35 is provided with a cooling groove 35b for supplying a coolant to the movable mirror surface plate 3
5 can be cooled.

Further, an outer peripheral ring 41 for holding the outer edge portion of the stamper attached to the cavity surface 35a for forming unevenness on the information surface of the molded disk is installed around the movable side mirror surface plate 35. There is. Further, a cylindrical stamper holder 43 which is fitted to the movable side mirror surface plate 35 and the second movable member 33 and holds the inner edge portion of the stamper is provided. Thereby, the inner and outer edges of the stamper are held and the cavity surface 35a of the movable side mirror surface plate 35 is held.
It is attached closely to. Therefore, the cavity 45 formed when the injection molding die 1 is closed is, to be exact,
It is formed between the cavity surface 13a of the fixed-side mirror surface disk 13 and the stamper attached to the cavity surface 35a of the movable-side mirror surface disk 35.

The stamper holder 43 includes a second movable member 3
3 and the movable side mirror surface plate 35 are fitted with a stationary sleeve 47. The stationary sleeve 47 is fixed coaxially with the disk center of the movable side mirror surface plate 35, and has a core-retaining function for a part to be fitted in or out of the stationary sleeve 47.

An ejector sleeve 49 is slidably inserted in the stationary sleeve 47 along the axial direction. The rear end of the ejector sleeve 49 is connected to the ejector sleeve drive member 51 housed in the first movable member 31. The ejector sleeve drive member 51 is movable in the space formed in the first movable member 31 along the axial direction of the ejector sleeve 49. The ejector sleeve 49 and the ejector sleeve drive member 51 are urged in the arrow Y direction by a spring (not shown) interposed between the ejector sleeve 49 and the ejector sleeve drive member 51. Further, the ejector sleeve drive member 51 has a rear end in contact with the front end of a pin 53 that is reciprocally driven by a hydraulic cylinder (not shown). Therefore, pin 5
When 3 is driven forward along the arrow X direction, the ejector sleeve 49 is moved forward through the ejector sleeve drive member 51 along the arrow X direction.

The tip of the ejector sleeve 49 has a pin 5
3 is not moved forward, it is located substantially on the same plane as the cavity surface 35a of the movable side mirror surface plate 35, but the pin 5
When it is driven by 3 and moves forward, the tip can project from the cavity surface 35a along the arrow X direction. When the pin 53 is in the retracted position, it is held in the retracted position by the action of the spring.

The ejector sleeve 49 penetrates through the first movable member 31, the second movable member 33 and the movable mirror surface plate 35, and the tip thereof slightly protrudes from the cavity surface 35a of the movable mirror surface plate 35 to form a movable mirror surface. A gate cutter 55, which is assembled so as to be able to move forward and backward along the disc center line of the board 35, is slidably inserted.

The gate cutter 55 is biased in the arrow Y direction by a spring (not shown) interposed between the gate cutter 55 and the first movable member 31. Further, a projection 57 is provided at the rear end of the gate cutter 55, and the projection 57 has a pin 5 reciprocally driven by a hydraulic cylinder (not shown).
The tip of 9 is abutted. Therefore, when the pin 59 is driven forward along the arrow X direction, the gate cutter 5
5 is moved forward along the arrow X direction. When the pin 59 is at the retracted position, the gate cutter 55 is
It is held in the retracted position by a spring.

The gate cutter 55 has an outer diameter corresponding to the inner diameter of the center hole of the molded disk. At the same time, the outer diameter of the gate cutter 55 is slightly smaller than the inner hole 19a of the guide bushing 19, and the tip can be fitted into the inner hole 19a when the gate cutter 55 advances.

As shown in FIGS. 1 and 2, the gate cutter 55 is provided with an ejector pin insertion hole 61, and the inner surface of the end of the ejector pin insertion hole 61 in the direction of arrow X extends along the circumferential direction. A groove-shaped recess 62 is provided. The ejector pin 63 is slidably inserted into the ejector pin insertion hole 61. The tip surface 63a of the ejector pin 63 is substantially aligned with the tip surface 55a of the gate cutter 55. Therefore, the ejector pin 63
Closes the recess 62 to form an annular space. The ejector pin 63 is urged in the direction of the arrow Y by a spring (not shown) interposed between the ejector pin 63 and the first movable member 31, and the rear end protrusion provided at the rear end of the ejector pin 63. The tip of a pin 67 that is reciprocally driven by a hydraulic cylinder (not shown) is in contact with 65.
As a result, when the pin 67 is driven forward along the arrow X direction, the ejector pin 63 is moved forward along the arrow X direction, and when the pin 67 is in the retracted position, the ejector pin 63 is operated by the spring. 63 is also held in the retracted position. Further, when the gate cutter 55 moves forward along the direction of the arrow X and the ejector pin 63 is held at the retracted position, the relative position between the ejector pin insertion hole 61 and the ejector pin 63 fluctuates, and the ejector pin 63 changes. Is relatively retracted in the arrow Y direction with respect to the ejector pin insertion hole 61, and the tip surface 63 of the ejector pin 63 is
a is stored in the ejector pin insertion hole 61. As a result, a columnar space in which the ejector pin 63 is not inserted, that is, the sprue puller hole 69 is formed at the end of the ejector pin insertion hole 61 on the ejection hole 23 side.

A mold clamping ram (not shown), which is driven by a mold clamping cylinder and moves the movable plate 9 forward and backward along the stay 3, is fixed behind the movable plate 9. As a result, the movable mold 39 is closed, clamped,
It is possible to perform each operation of mold opening.

Next, a process of molding a disc by an injection molding machine equipped with the injection molding die 1 will be described.
A stamper corresponding to the disk to be molded is attached to the movable side mirror surface plate 35 in advance via the stamper holder 43 and the outer peripheral ring 41.

First, the mold clamping ram is moved forward to move the movable die 39 together with the movable platen 9. The movable mold 39 and the fixed mold 17 are closed and clamped to form a cavity 45 between the fixed side mirror surface plate 13 and the movable side mirror surface plate 35. At this time, the movable-side locating block 37 and the fixed-side locating block 15 are in close contact with each other in a tapered manner, so that the fixed mold 17 and the movable mold 39 are retained.

Next, the heating cylinder is advanced to bring the front end of the injection nozzle into close contact with the nozzle contact surface 25 formed at the rear end of the sprue bushing 21. Subsequently, the molten resin supplied from the heating cylinder is injected and filled into the cavity 45 through the injection hole 23 formed by the sprue hole 21a of the sprue bushing 21 and the inner hole 19a of the guide bushing 19.

When a predetermined time corresponding to the completion of filling has elapsed, the hydraulic cylinder is operated to move the pin 59 forward in the direction of arrow X in FIG. The gate cutter 55 driven by the pin 59 penetrates the cavity 45 and projects forward to close the injection hole 23 (gate cut). This prevents further injection of molten resin into the cavity 45. With the advance of the gate cutter 55, the relative position between the ejector pin insertion hole 61 and the ejector pin 63 is changed, and the ejector pin 63 is retracted in the arrow Y direction relative to the ejector pin insertion hole 61. And the injection hole 23 of the ejector pin insertion hole 61.
A sprue hole 69 is formed at the side end. Since the molten resin continues to flow into the cavity 45 until the gate cut is completed, the sprue hole 69 thus formed is formed.
Molten resin flows into and is filled in. Further, the forward protrusion of the gate cutter 55 not only cuts off the resin supply to the cavity 45, but also the resin inside the cavity 45 and the injection hole 23.
At the same time as separating the resin inside, a function of forming a central hole in the resin inside the cavity 45 is also achieved. Further, since the gate is cut while the resin is in the molten state to prevent the injection of the excess resin, the internal pressure of the cavity 45 does not rise excessively. Therefore, residual strain or the like does not occur in the manufactured disc.

In this state, the solidification of the resin is awaited. After the solidification time has elapsed, the resin solidified in the cavity 45 becomes a product disk, and the resin solidified in the injection hole 23 and the sprue puller hole 69 becomes a sprue 70. Since the sprue puller portion 70a solidified in the sprue puller hole 69 of the sprue 70 is engaged with the recessed portion 62 provided in the ejector pin insertion hole 61, the sprue 7 is formed by the engagement.
0 is held at the tip of the gate cutter 55. Therefore, when the mold clamping ram is retracted and mold opening is started after the solidification time has elapsed, the sprue 70 is held at the tip of the gate cutter 55 and is separated from the injection hole 23. This state is shown in Figure 2.
It shows in (a).

After completion of mold opening, when the hydraulic cylinder is operated to drive the pin 67 forward, the ejector pin 63 projects forward along the direction of arrow Z in FIG. 2 to press the sprue puller portion 70a to push the sprue 70 to the gate cutter 55. Stick out from the tip of the and detach it. The sprue 70 receives a pressing force along the arrow Z direction by the ejector pin 63 and moves in that direction. At this time, the resin in the portion engaged with the recess 62 is elastic in the direction of reducing its outer diameter. It deforms and cancels the engaged state. Therefore, the engagement of the sprue puller portion 70a in the recess 62 does not hinder the ejection of the sprue 70 by the ejector pin 63. When the tip of the ejector pin 63 reaches a position substantially matching the tip of the gate cutter 55, the sprue 70 separates from the gate cutter 55 [see FIG. 2 (b)].

As described above, there is no portion for fixing the sprue 70 to the gate cutter 55 by engagement or the like except for the sprue puller portion 70a which engages with the recess 62. Moreover, the pressing force of the ejector pin 63 acts on the bottom portion of the sprue puller portion 70a along the axis of the shaft-shaped portion 70b of the sprue 70. Therefore, when ejected by the ejector pin 63, only the shaft-like portion 70b of the sprue 70 is not separated and ejected. Even if the sprue 70 is not completely solidified, the shaft-like portion 70b of the sprue 70 is projected along the axial direction through the bottom portion of the sprue puller portion 70a as described above.
Only the part is separated from the other parts and is not projected.

Following the ejection of the sprue 70, the ejector sleeve 49 starts to move forward, and the disc is peeled off from the stamper on the mirror surface plate 35. The disc and the sprue 70 that have been peeled off can be taken out by an appropriate take-out means equipped with a suction cup or the like.
It is taken out from the injection mold 1.

As described above, according to the injection molding die 1 of this embodiment, the sprue 70 can be reliably removed from the tip of the gate cutter 55 when the die is opened, and the sprue 70 is not completely solidified. However, only the shaft-shaped portion 70b of the sprue 70 is not separated and projected. Therefore, it is not necessary to secure an unnecessarily long time for solidifying the sprue 70, so that the solidifying time of the sprue 70 can be shortened and the cycle can be increased. Further, it is possible to prevent the mold from being damaged due to the mold being closed to start the next injection molding while the cup-shaped portion 70c of the sprue 70 is attached to the tip of the gate cutter 55.

Although one embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to such an embodiment and can be implemented in various modes without departing from the scope of the invention. Nor. For example, in the present embodiment, the recess 62 formed in the ejector pin insertion hole 61 has a groove shape that makes one round along the circumferential direction, but it does not necessarily have to make one round, and a plurality of recesses may be provided along the circumferential direction. . Further, the ejector pin insertion holes 61 may be provided at a plurality of locations along the axial direction.

[0038]

As described above, according to the injection mold of the present invention, the sprue associated with injection molding can be reliably removed from the tip of the gate cutter.

[Brief description of drawings]

FIG. 1 is a sectional view of an injection mold of an example.

FIG. 2 is an explanatory view of a tip portion of the gate cutter and a state of sprue when the mold is opened and when the sprue is projected in the injection molding die of the embodiment.

FIG. 3 is an explanatory view of a state of a gate cutter tip portion and a sprue when a mold is opened and a sprue is projected in a conventional injection molding die.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Injection mold, 7 ... Fixed plate, 9 ... Movable plate, 13 ... Fixed side mirror surface plate, 17 ... Fixed mold, 2
3 ... injection hole, 35 ... movable side mirror surface plate, 39 ...
Movable mold, 45 ... Cavity, 55 ... Gate cutter, 61 ... Ejector pin insertion hole, 62 ... Recessed portion, 63 ... Ejector pin, 63a ... Tip surface,
69 ... Sprue puller hole, 70 ... Sprue, 70a
... Sprue puller part, 70b ... Shaft part, 70c
... Cup-shaped part.

Claims (1)

[Claims] 1. An injection molding machine comprising a fixed mold fixed to a fixed platen and a movable platen fixed to a movable platen, wherein the two molds are between the joint surfaces when the both molds are closed. It is equipped with a mirror surface plate that forms a disk-shaped cavity, has an injection hole that opens in the center of the mirror surface plate of the fixed mold and allows molten resin to pass through, and is arranged concentrically with the mirror surface plate of the movable mold. A gate cutter capable of advancing and capable of gate cutting by inserting the tip into the injection hole when advancing, and an ejector pin insertion hole formed in the gate cutter concentrically with the gate cutter and opening at the tip surface of the gate cutter. In an injection molding die provided with an ejector pin that is inserted through the ejector pin insertion hole so as to be able to move forward and backward, a tip end surface of the ejector pin on the injection hole side is housed in the ejector pin insertion hole when the gate is cut. A spout puller hole having a columnar space is formed by the tip surface of the ejector pin and the ejector pin insertion hole, and a recess is provided in an end inner hole forming the sprue hole of the ejector pin insertion hole. Molding die.