JPH0371254B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a molding method for injection molding a disk such as a digital audio disk called a compact disk, and to improvements in a molding apparatus.

[Conventional technology]

A conventional disc molding die is shown in FIG. 7, and the disc molding process using the same will be explained below.

In the figure, numeral 1 is a fixed type installed on the resin injection side of the injection machine, and 2 is a movable type installed on the slide side for clamping and opening the mold.

3 is a cavity provided in the movable mold 2 facing the parting line of the movable mold 2 and the fixed mold 1;
A stamper 4 on which a group of signals is formed is mounted on the back surface thereof.

A sprue bush 5 having the same diameter as the center hole of the disk is inserted into the fixed mold 1, and the sprue bush 5 is pressed into contact with an injection nozzle 6 of an injection injection machine, and the resin injected from the injection nozzle 6 is The sprue bush 5 is injected into the sprue hole 7.

A center pin 8 is inserted into the movable mold 2 facing the sprue bush 5, and a gate 9 for injecting resin into the cavity 3 is formed between the center pin 8 and the sprue bush 5. There is.

A reverse tapered cold slug well 10 is formed in the center of the center pin 8, and an extrusion pin 11 is inserted through the center of the cold slug well 10. A spring 12 is installed between the spring 11 and the spring 11.

This extrusion pin 11 faces an extrusion cylinder 13 of an injection machine.

To mold a disk using this mold,
After the movable mold 2 is moved and pressed against the fixed mold 1, molten resin is injected from an injection nozzle 6 of an injection machine.

Then, the resin passes through the sprue hole 7 and enters the gate 9.
is injected into the cavity 3, and at the same time fills the cavity 3, the cold slag well 1 is injected into the cavity 3.
0. Also fill the sprue hole 7.

Then, by cooling the fixed mold 1 and the movable mold 2,
After waiting for the molten resin to solidify, the sprue bush 5 and center pin 8 are moved to cut the gate 9 portion of the disk inside the cavity 3.

Next, the movable mold 2 is moved to take out the molded disk, but when opening the mold,
Since the cold slug well 10 has a reverse taper, the resin 14 filled in the sprue hole 7 (hereinafter referred to as sprue) is held by this part and transferred to the movable mold 2.
The sprue 14 is pulled out from the sprue hole 7.

After that, the extrusion cylinder 13 of the injection extrusion machine operates to push the extrusion pin 11 against the spring 12, and the pushed extrusion pin 11 pushes the sprue 14 gripped by the cold slug well 10.
This is separated from the mobile type 2.

Discs are produced by repeating the above operations.

[Problem that the invention seeks to solve]

Conventionally, the injection molding of a disk is carried out as described above, but the gap between the cavity 3 for molding the disk is as thin as about 1 mm, and therefore the cooling of the fixed mold 1 and the movable mold 2 can be used to It solidifies in time.

On the other hand, since the sprue 14 has a large diameter of several millimeters, it takes time to solidify through the cooling described above, and its length also lengthens the shot cycle, reducing productivity. is inhibiting.

Also, the sprue 14 is connected to the cold slug well 1.
The closer the diameter is to 0, the larger the diameter, so due to contraction during solidification, a vacuum bubble 15 is generated at the center of the part as shown in Figure 8a, or as shown in Figure 9a. Sink 1 at cold slug well 10
6 or create a vacuum bubble 15 as shown in Figure 10a.
A sink mark 17 is likely to be formed on the outer shape of the part where this occurs.

When the vacuum bubble 15 shown in FIG. 8a is generated, as shown in FIG. 8b, the sprue 14 is
When it is pulled out from the sprue hole 7, it is cut at that part and the sprue hole 7 is clogged.

When the sink mark 16 shown in FIG. 9a occurs, the sprue 14 comes off from the cold slug well 10, remains in the sprue hole 7, and clogs the sprue hole 7.

If the sink mark 17 shown in Fig. 10a occurs, the sprue 4 will not only be cut at that part and clog the sprue hole 7 as shown in Fig. 8b, but also the sprue 4 will hang down as shown in Fig. 10b. There is a risk.

If the sprue 14 cannot be dropped below the mold attachment part of the injection machine and the sprue 14 is to be grabbed and taken out by a robot, the 10th
If it hangs down as shown in Figure b, the robot will be unable to grasp it.

In order to increase the productivity of the injection machine, if the shot cycle is shortened, the mold is opened before the sprue 14 is completely solidified.
The above-mentioned danger is further exacerbated.

In addition, in order to promote cooling of the sprue hole 7, if the mold temperature in that part is lowered, the molten resin will pass through that part during resin injection, causing the temperature of the resin to drop and the inflow of low-temperature resin. There are many problems, such as many negative effects on molded products.

[Means for solving problems]

In order to solve the above-mentioned problems in conventional disk manufacturing, the present invention operates an extrusion pin to pressurize the resin in the sprue hole after injection is completed.
The means includes a gate for injecting resin into a cavity in which one side of the stamper is attached;
Before the resin in the sprue solidifies, a push pin installed opposite the sprue between the injected resin receiving port and the injection injection machine compresses the resin in the sprue, and after the mold is opened. This is accomplished by a disk manufacturing method and molding apparatus in which the extrusion pin is extruded again, the sprue is extruded, and the sprue is removed.

[Effect]

The present invention prevents vacuum bubbles and sink marks from forming on the sprue by pressurizing and solidifying the molten resin filling the sprue hole through the primary operation of the extrusion pin after injection is completed. , prevents the sprue from being cut or pulled out of the cold slug well when opening the mold, prevents the sprue hole from clogging, and prevents the sprue from hanging down so that the robot can grip it reliably. Make it.

After opening the mold, the ejector pin is operated again to push the sprue and remove it from the mold.

[Embodiments of the invention]

The manufacturing method of the present invention will be described below with reference to FIG.

Figure a shows the resin injection and filling process, and the extrusion pin 11 inserted into the center of the cold slag well 10
I'm waiting at a position deeper than the bottom of the 0.

FIG. 1B shows a cooling process, which begins after the completion of the above-mentioned process, during which vacuum bubbles 15 and sink marks tend to form on the sprue 14.

Figure c shows the forward movement of the extrusion pin 11 during the cooling process, and the extrusion pin 11 advances to the bottom surface of the cold slug well 10.

Since the sprue 14 is pressurized by its advancement, no vacuum bubbles 15 or sink marks are generated during solidification.

Figure d shows the mold opening process after the resin solidifies, and the sprue 14 is connected to the cold slag well 10.
It's firmly attached to it and won't come out.

FIG.
4 is forcibly extruded.

As described above, when the manufacturing method of the present invention is used, clogging of the sprue hole 7 due to cutting of the sprue 14 or removal from the cold slug well 10 is prevented, and the robot is prevented from failing to grasp the robot due to the drooping of the sprue 14. Nor.

Further, even if the shot cycle is somewhat shortened, there is no adverse effect on the product, and as mentioned above, the sprue hole is not clogged or the robot fails to grasp the sprue, thereby increasing production efficiency.

Next, a first embodiment of the control means for the molding apparatus of the present invention will be described with reference to FIG. 2, and the mold used in this molding apparatus is the one shown in FIG. 7.

In Fig. 2, P is a hydraulic power source, _M1 is a direction control valve that controls the operating direction of the extrusion cylinder 13, and A is a speed control section, which is composed of a speed switching valve _M2 and a speed adjustment valve _T1 , and is directional control. The valve M ₁ , the speed switching valve M ₂ , and the speed adjustment valve T ₁ are operated by a timer according to the shot cycle of mold opening and resin injection.

When the resin filling is completed, the direction control valve _M1 operates and moves to the x position, and at the same time the speed switching valve
M ₂ becomes the t position.

Therefore, the pressure from the pressure source P is
M ₁ enters the p side of the extrusion cylinder 13 .

At the same time, the pressure on the q side of the extrusion cylinder 13 is sent to the speed control section A by the directional control valve _M1 .

At this time, the speed switching valve _M2 is in the t position and does not allow this oil pressure to pass, so the oil pressure is transferred to the speed adjustment valve.
It will pass through _T1 , its speed will be adjusted, and it will return to the hydraulic pressure source p.

By adjusting the amount of passage through the speed regulating valve _T1 , the extrusion cylinder 13 operates slowly and pushes the extrusion pin 11 at a slow speed, so that the state c in FIG. 1 can be achieved.

After the start of the operation, for example, 4 to 5 seconds later, the directional control valve _M1 is switched to the y position by a timer, and the extrusion cylinder 13 stops its operation.

Next, in connection with the mold opening, the timer operates, and the directional control valve _M1 is switched to the x position again, and at the same time,
The speed switching valve _M2 is also switched to the s position, and the pressure on the q side of the extrusion cylinder 13 quickly returns to the hydraulic pressure source P, so the extrusion pin 11 is rapidly pushed and the sprue 14
Extrusion is performed.

After extrusion of the sprue 14, the directional control valve _M1 is switched to the z position, the p side and the q side of the extrusion cylinder 13 are connected to the pressure source P in the opposite direction, and the extrusion cylinder 1
3 moves in the opposite direction, and the push-out pin 11 is retracted.

Next, a second embodiment of the control means for the molding apparatus of the present invention will be described with reference to the circuit shown in FIG. 3, and the mold used in this molding apparatus is the one shown in FIG. 7.

In Fig. 3, _M1 is the directional control valve of the previous embodiment.
The same directional control valve as _M1 , B is a pressure control unit, consisting of a pressure exchange valve _M3 and a pressure reducing valve _RD1 , P is a hydraulic power source,
Generates a pressure of about 150Kg/.

When the injection machine finishes injecting the resin and reaches the state shown in _FIG . The switching valve _M3 is also operated and switched to the n position.

Therefore, the pressure from the hydraulic source P is reduced by the pressure reducing valve RD ₁ and passes through the n position of the pressure switching valve M ₃ to the x position of the directional control valve M ₁ to the p side of the extrusion cylinder 13. Get in and move this forward.

At this time, the pressure on the q side of the extrusion cylinder 13 passes through the x position of the directional control valve _M1 and is returned to the hydraulic pressure source P.

In this way, the extrusion cylinder 13 can be operated at low pressure to achieve the condition of FIG. 1c.

Then, as in the previous embodiment, after a predetermined period of time has elapsed after the directional control valve M ₁ is operated to the x position, the directional control valve M ₁ is operated again and switched to the y position, and the extrusion cylinder 13 is switched to the p side. Since the supply of hydraulic pressure to the q side and the discharge of the hydraulic pressure on the q side are stopped, the extrusion cylinder 13 is stopped.

Next, a timer operates in conjunction with the mold opening, and the direction control valve _M1 is switched to the x position, and at the same time, the pressure switching valve _M3 is also switched to the m position, and the pressure of the hydraulic source P is directly applied to the extrusion cylinder. 13p side, the extrusion cylinder 13 operates under high pressure, and the extrusion pin 11 extrudes the sprue 14 from the cold slag well 10 as shown in FIG. 1e.

After the ejection is completed, the directional control valve _M1 is changed to the z position, high pressure is supplied to the q side of the extrusion cylinder 13, and the p side is brought back into contact with the hydraulic pressure source P, so that the extrusion cylinder 13 is returned to its initial position, and the push-out pin 11 is retracted to the position a in FIG. 1.

Next, a third embodiment of the molding apparatus of the present invention will be described with reference to FIG. 4. In this molding apparatus, the apparatus shown in FIG. 4 is added to the mold shown in FIG. 7.

In FIG. 4, 2 is a movable mold, 11 is an extrusion pin 12 is a spring, and 13 is an extrusion cylinder, which are the same as those in FIG.

Reference numeral 20 denotes an interlocking rod attached to the tip of the ram of the extrusion cylinder 13, and a cylinder 22 that operates a stopper 21 that stops the forward movement of the flange 20a midway.
The movable die 2 is also provided with a second stopper 23 for finally stopping the flange 20a.

Then, the extrusion cylinder 13 is operated from the end of the injection shown in FIG. 1b to push the extrusion pin 11, and when the state shown in FIG. The operation of pin 11 is stopped.

Next, when transitioning from the mold opening shown in FIG. 1d to the state shown in FIG. 1e, where the sprue 14 is pushed out and removed, the cylinder 22 is operated to retract the stopper 21 from the flange 20a.

As a result, the extrusion cylinder 13 advances further and the extrusion pin 11 extrudes the sprue 14.

Furthermore, a fourth embodiment of the molding apparatus of the present invention will be described with reference to FIG. 5, in which the apparatus shown in FIG. 5 is added to the mold shown in FIG. 7.

In FIG. 5, 2 is a movable mold, 11 is an extrusion pin 12 is a spring, and 13 is an extrusion cylinder, which are the same as those in FIG.

25 is a compression cylinder 26 which causes the push-out pin 11 to perform the first stage operation, and is a stopper.

During the molding process, when state b in Figure 1 is reached,
The compression cylinder 25 operates and becomes the state shown in FIG. 1c, and after the mold is opened as shown in FIG. 1d, the extrusion cylinder 13
operates, and the ejector pin 11 ejects the sprue 14.

Furthermore, in the embodiment shown in FIG. 6, a fixed rod 27 that does not move even if the movable mold 2 moves is provided in place of the extrusion cylinder 13 of the previous embodiment, and the first stage operation of the extrusion pin 11 is as follows. As in the previous embodiment, this is performed by the operation of the compression cylinder 25.

Then, before the mold opening is completed, the ejector pin 11 hits the fixed rod 27, preventing the ejector pin 11 from moving all over the movable mold 2, ejects the ejector pin 11 into the cold slug well 10, and sprues the sprue. 14 sticks out.

〔Effect of the invention〕

As described above, in the present invention, immediately after injection is completed, the extruder pin is operated in the first stage to continue pressurizing the resin on the sprue from a molten state to a solidified state, and by this pressurization, This prevents vacuum bubbles and sink marks from forming on the sprue.

This prevents the sprue from being cut off by vacuum bubbles or sink marks and remaining in the sprue hole when the mold is opened.

Further, since the sprue is prevented from coming off from the cold slug well and remaining in the sprue hole due to sink marks, the injection hole is not closed due to remaining sprue, and there is no need to stop the machine and remove it.

Furthermore, when the sprue is grabbed and removed by the robot, the sprue will not hang down, so the robot will not fail to grasp it, and the sprue will get caught between the fixed mold and the movable mold, making it impossible to close the mold. There is no.

Moreover, since there is no need to cool the sprue to solidify it early, the molded product will not be adversely affected by the low temperature of the resin flow path, and high-quality molded products can be obtained without complicated temperature control of the sprue. .

Furthermore, even if the shot cycle is set to a speed similar to that of performing cooling that quickly solidifies the sprue portion, no problem will occur, so production efficiency can be improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the molding process of the present invention, FIG. 2 is an explanatory diagram of a circuit of an embodiment of the control device of the present invention, and FIG.
The figure is a circuit explanatory diagram of another embodiment of the control device of the present invention, Figures 4 to 6 are schematic diagrams of a part of the molding die according to the present invention, and Figure 7 is a schematic diagram of a conventional molding die. illustration,
FIGS. 8 to 10 show the state of sprue failure and the troubles caused by this. 1...Fixed type, 2...Movable type, 3...Cavity, 4...Stand bar, 5...Sprue bush,
7... Sprue internal combustion, 8... Center pin, 9...
...Gate, 10...Cold Slagwell, 11
...Extrusion pin, 12...Spring, 13...Extrusion cylinder, 14...Sprue, 15...Vacuum bubble, 1
6, 17... sink mark, 20... interlocking rod, 21... stopper, 22... cylinder, 23... stopper,
25... Compression cylinder, 26... Stopper, 27
... Fixed rod, A ... Speed control section, B ... Pressure control section, M ₁ ... Directional control valve, M ₂ ... Speed switching valve,
M ₃ ...Pressure switching valve, T ₁ ...Speed adjustment valve, RD ₁ ...
…Pressure reducing valve.

Claims (1)

[Claims] 1. A push pin provided opposite to a sprue between a gate for injecting resin into a cavity to which a stamper is attached on one side and a receiving port for resin injected from a molding machine. is extruded before the resin in the sprue solidifies to compress the resin in the sprue, and after the mold is opened, the extrusion pin is extruded again to extrude the sprue and remove the sprue. Method. 2. An extrusion pin is provided opposite the sprue formed between the gate for injecting resin into the cavity, which is attached to one side of the stamper, and the receiving port for the resin injected from the molding machine. 1. A disk molding apparatus comprising a control means for controlling pressure reduction of a cylinder for operating an extrusion pin in two stages. 3. An extrusion pin is provided opposite the sprue formed between the gate for injecting resin into the cavity, which is attached to one side of the stamper, and the receiving port for the resin injected from the molding machine. A disk molding device comprising a cylinder for operating an extrusion pin and a limiting means for limiting the movement and distance during the operation process of the cylinder. 4 An extrusion pin is provided opposite the sprue formed between the gate for injecting resin into the cavity, which is attached to one side of the stamper, and the receiving port for the resin injected from the molding machine. A disk molding device characterized by being provided with two cylinders to operate an extrusion pin in two stages. 5 An extrusion pin is provided opposite the sprue formed between the gate for injecting resin into the cavity, which is attached to one side of the stamper, and the receiving port for the resin injected from the molding machine. A cylinder that uses an extrusion pin to perform the first stage operation;
A disk molding device characterized in that it is provided with interlocking means for operating the ejecting pin in conjunction with mold opening in order to cause the ejecting pin to perform a second stage operation of extruding the sprue.