JP3817341B2 - Injection molding machine - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an ultra-precise molding injection molding machine that uses a servo motor as each drive source in an injection molding process and further uses a toggle mechanism as its compression mechanism.
[0002]
[Prior art]
An injection molding machine using a servo motor as a driving source for each process is already widely used. However, even in that case, (1) injection of metering resin into the mold cavity, (2) metering of kneaded resin, and (3) use of a servo motor for each drive source such as mold opening and closing is at most. .
Recently, however, digital technology has become universal in various fields including data processing, video and music, and as a natural consequence, digital substrates such as CD, MD, and DVD have been put into practical use. In particular, the DVD substrate is required to accurately transfer the ultra-fine irregularities engraved on the mold to the molded product, and the conventional injection molding machine is not useful at all. The injection molding machine to be used was developed. In such an injection molding machine, the following matters affect the substrate accuracy.
[0003]
For example, taking optical disk substrate molding as an example, warping of molded products, adhesion of foreign matter, voids, gas burns, molding cycle, etc. are extremely important factors, but the biggest problems are (1) ultrafine pitch, (2). ▼ Depth transferability of depth, and (3) Realization of birefringence of 50 nm or less, and (bielasticity x principal stress difference "= shear stress + thermal stress") can be reduced to suppress birefringence. I can do it.
[0004]
Now, as the factors that hinder the transferability of fine irregularities in substrate molding, (1) microvoids and (2) microflow marks can be mentioned.
When the resin flows along the fine unevenness, an air entrainment phenomenon occurs in the resin flow before and after the fine uneven wall, thereby forming a fine air reservoir. This minute air reservoir causes a decrease in transferability, and a countermeasure is to complete the filling by suppressing the solidification of the resin by high-speed filling as much as possible. Also, the timing of injection compression is an important factor.
[0005]
[Problems to be solved by the invention]
In view of this, it is impossible to achieve these items without excess or deficiency with conventional injection molding machines using servo motors, and development of new injection molding machines has been desired.
[0006]
[Means for Solving the Problems]
“Claim 1” is an “injection molding machine (A) used in a core compression injection molding method for precision molding, in which a metering resin (3a) is injected into a mold cavity (2), and a kneaded resin (3b) Weighing, opening and closing of the mold (1), opening and closing of the core mold (5) disposed in the mold (1), gate cutting after filling the mold cavity (2) with the weighing resin (3a), Servo motors (11) (12) (31) and (40) are used as drive sources for compression of the filled resin (3) by the core mold (5) after gate cutting, and the mold opening and closing mechanism of the mold (1) as, using a mold opening and closing the toggle mechanism (T1) which is actuated by the forward or backward of the male screw rod (30a), the tip of the male screw rod (30a) intermediate pins (30b) and pin pressure rod (30c) via connected to the gate cut pin (30), characterized in the "possible to close the advancing gate cut pin (30) by forward movement of the male screw rod (30a) and a gate (2a).
[0007]
According to this, since all operations of the injection work are controlled by the servo motors (11) (12) (31) and (40), the timing, injection speed, pressurization speed, pressurization pressure, etc. It can be freely controlled, and the transferability to the molded product with ultra-fine irregularities can be remarkably improved. In addition, the servo motors (11) (12) (31) and (40) are combined. It is possible to improve the cycle.
[0008]
“Claim 2” is characterized in that “the toggle mechanism (T2) is used as the compression mechanism of the filling resin (3) by the core mold (5)”.
The compression of the filling resin (3) by the core mold (5) requires almost the same force as the mold clamping force of the mold (1), but this reduces the compression pressure of the core mold (5) to the mold (1 ) The mold clamping pressure can be almost the same.
[0009]
“Claim 3” is characterized in that “the bearing (46) is used for the rotational connection portion (H2) between the arms (47) constituting the toggle mechanism (T2)”.
In ultra-precision molding, not only the accuracy of the fine unevenness forming surface (5a) of the core mold (5), the movement of the core mold (5) must be extremely precise and smooth, and the bearing (46 ) Was able to eliminate rattling and irregularities at the rotating joint (H2), which were the disadvantages of the conventional toggle mechanism using metal sliding bearings.
[0010]
【Example】
Hereinafter, the present invention will be described in detail according to illustrated embodiments. In the attached drawings, FIGS. The injection molding machine (A) of the present invention is roughly divided into an injection mechanism part (a) and a mold mechanism part (b) as shown in FIG.
The injection mechanism (a) is a drive mechanism (10) for moving the screw (4) forward / backward, a servo motor (11) for rotating the screw (4), and a screw (4) moving forward / backward. Servo motor for injection (12), screw for raw material kneading and injection (4), injection cylinder (13) in which screw (4) can be moved forward and backward, and rotatable, heater wound around injection cylinder (13) (14), an injection load cell (15) disposed between the screw (4) and the drive mechanism (10) for detecting the pressure applied to the screw (4), the raw material supply hopper (16), and each It consists of pulse generators (11a) and (12a) mounted on servo motors (11) and (12).
[0011]
Next, the mold mechanism (b) will be described. The mold (1) consists of moving and fixed molds (1a) and (1b), the fixed mold (1b) is mounted on the fixed die plate (17), and the movable mold is mounted on the movable die plate (18). (1a) is installed. The moving die plate (18) is fitted with a core type opening / closing toggle mechanism (T2), and the tailstock (1) is fixed to the housing (50) of the core type opening / closing toggle mechanism (T2). A mold opening / closing toggle mechanism (T1) is disposed between (20) and (20).
[0012]
A guide hole (29) is formed in the movable mold (1a), and a core mold (5) is slidably disposed in the guide hole (29). A mold cavity (2) is formed between (1b). The surface (5a) on the mold cavity (2) side of the core mold (5) is formed with fine irregularities for, for example, CD and DVD, and the side fine irregularity engraved surface (5a) is like a super mirror finish And extremely high smoothness (for example, Rmax 0.01 μm, flatness = 0.1 μm) is required, the parallelism is, for example, 0.005 mm or less, and the coaxiality between the core mold (5) and the guide hole (5a) is, for example, 0.00. An extremely high accuracy such as 005 mm is required.
Further, a gate cut pin (30) is slidably disposed at the center of the core mold (5).
[0013]
Next, the mold opening / closing toggle mechanism (T1) will be described. A mold control servo motor (31) is attached to the tailstock (20), and the drive pulley (32) attached to the rotary drive shaft and the tailstock (20) are rotatably arranged via a bearing. The driven pulley (34) provided is connected. A pulse generator (31a) is mounted on the mold control servomotor (31).
A male threaded rod (30a) is screwed to the driven pulley (34) so as to be able to advance and retreat, and a protruding end of the male threaded rod (30a) is attached to the mold opening / closing cross head (35). The mold opening / closing toggle has long and short arms (36) connected to a link mechanism, one end of which is pivotally connected to the tailstock (20) and the other end is pivotally connected to the housing (50). The other end is attached to the mold opening / closing cross head (35). Since this link mechanism is a known technique, further details are omitted.
[0014]
Next, the core type opening / closing toggle mechanism (T2) will be described. The housing (49) constituting the front end portion of the core type opening / closing toggle mechanism (T2) is connected to the movable die plate (18), and further to the housing (50) constituting the rear end portion via the core type opening / closing toggle. It is connected. A core type control servo motor (40) is attached to the housing (50), and a drive pulley (41) attached to the rotary drive shaft and rotatably held by the housing (50) via a bearing. The driven pulley (43) is connected by a transmission belt (42). The driven pulley (43) is attached to an operating nut (45), and a core operating screw rod (44) is screwed to the operating nut (45) so as to be able to advance and retract. An intermediate pin (30b) connected to the gate cut pin (30) is slidably inserted into the core actuating screw rod (44), and the tip thereof is connected to the pressure plate (59). Is configured to come in contact with the tip of the male screw portion (30a). The core type control servo motor (40) is provided with a pulse generator (40a).
[0015]
The core-type opening / closing toggle used in the above is the same as the mold opening / closing toggle, but with various short and long arms (47) connected to the link mechanism, and the structure itself is a well-known structure, but its rotational connection part (H2) Is different from the conventional example in that a bearing (46) is interposed between the rotation pin (48) serving as the rotation center and the arm (47) so that the arm (47) operates smoothly without play. To do. The type of bearing (46) is not limited, but since a load is applied, a type capable of carrying a large load such as a roller bearing or a needle bearing is selected.
Briefly, one end of each of the long and short arms (47) is connected to the housing (49), the other end is connected to the housing (50), and the other end is connected to the core operating screw rod (44). It is attached to a core operation crosshead (55) provided at the tip.
[0016]
A pressure block (57) that pressurizes the core mold (5) is slidably disposed in the movable die plate (18) and is in contact with the housing (49) via the pressure sensor (54). . A pin pressing rod (30c) is slidably passed through the pressure block (57), pressure sensor (54) and housing (49), and its tip abuts on the gate cut pin (30), It is in contact with the pressure plate (59) through the casing of the cylinder (60) disposed at the other end.
The cylinder (60) is connected to a push-out operating pin (61) that is slidably inserted into a pin pressing rod (30c). The projecting operation pin (61) is, for example, a product projecting pin disposed so as to project and immerse from a portion outside the fine unevenness forming portion on the outer periphery of the mold cavity surface (5a) on the core mold (5) side. 61a) and a center pin (61b) inserted into the gate cut pin (30). The product protruding pin (61a) and the center pin (61b), as will be described later, release the product (26) and the gate resin (2b) adhering to the product (26) side when the mold is opened after the mold is opened. Any structure can be used as long as it can be used.
[0017]
(8) is a control device that controls the entire injection molding machine (A), and one of the functions is an injection load cell (15), a pressure sensor (54), a servo motor (11). (12) The pulse generators (11a) (12a) (31a) and (40a) attached to (31) and (40), and signals from other sensors are used to obtain servo motors (11) (12) ( Various controls including the control of 31) and (40) are performed. Since all control of the drive system is performed by the servo motors (11), (12), (31), and (40), arbitrary conditions such as complex operations can be created by programming.
[0018]
Next, the operation of the present invention will be described. When the raw material resin (3c) is put into the raw material supply hopper (16) and the rotation servo motor (11) is operated to rotate the screw (4), the raw material resin (3c) is gradually fed in the direction of the injection cylinder (13). Since the injection cylinder (13) is heated by the heater (14) wound around its outer periphery, the raw material resin (3c) that has entered the injection cylinder (13) is gradually melted and the screw (4 Kneaded by the rotating action of).
[0019]
With the rotation of the screw (4), the melt-kneaded resin (3b) is sent toward the tip of the injection cylinder (13) and stored at the tip. As a reaction, the screw (4) gradually moves backward, and finally reaches a preset backward stop position. At this point, resin weighing is complete.
Subsequently, the servo motor for rotation (11) is stopped and the servo motor for injection (12) is operated to project the screw (4) forward, and the measured melt-kneaded resin collected at the tip of the injection cylinder (13) (3a) is injected into the mold cavity (2).
[0020]
On the other hand, on the mold (1) side, first, as shown in FIG. That is, when the mold control servo motor (31) is operated, the rotational force is transmitted to the driven pulley (34) through the drive pulley (32) and the transmission belt (33), and the driven pulley (34) is rotated to be driven. The male screw rod (30a) screwed to the pulley (34) advances from the lower stage in FIG. 2 to the right as shown in the upper stage, and the cross head (35) is pushed forward to extend the mold opening / closing toggle. At this time, the core opening / closing toggle mechanism (T2), the moving die plate (18), and the moving mold (1a) attached thereto move to the fixed mold (1b) side in accordance with this extension, and the fixed mold ( The moving mold (1a) is pressed to 1b) with a predetermined pressure. At this time, the core opening / closing toggle mechanism (T2) is not operated, and the core mold (5) is located at the retreat limit.
[0021]
Next, the state shown in FIG. Here, the core mold (5) moves to the forward limit. That is, when the core opening / closing servo motor (40) is operated, the rotational force is transmitted to the driven pulley (43) via the driving pulley (41) and the transmission belt (42), and when the driven pulley (43) is rotated, the driven is driven. The core actuating screw rod (44) screwed to the pulley (43) advances to the right in the figure, and the core actuating screw rod (44) is attached to push the core actuating crosshead (55) into the core type. Extend the open / close toggle. At this time, the housing (49) to which one end of the arm (47) of the core opening / closing toggle is pivotally attached is pushed out to the stationary mold (1b) side in accordance with this extension, and the pressure sensor (54) and the pressure block (57) Through which the core mold (5) moves to the fixed mold (1b) side. The pressurization pressure of the core type (5) is detected by the pressure sensor (54), and the data is input to the control device (8) (30), and the core type control servomotor (40 ) Is controlled.
[0022]
Next, the process moves to FIG. In this state, the injection servo motor (12) is operated as described above to operate the screw mechanism (10), the screw (4) is moved to the mold (1) side, and the metering kneading of the tip of the cylinder (13) is performed. Molten resin (3a) is injected into the mold cavity (2). The injection speed is optimally controlled by the control device (8). When the resin (3a) is injected and filled into the mold cavity (2), it comes into contact with and presses the core mold (5), and the core mold (5) is pushed back by the filling pressure. The melt-kneaded resin (3) is filled excessively.
[0023]
Next, gate cutting is performed as shown in FIG. That is, when the mold control servo motor (31) is further operated while the mold (1) is being clamped, the male screw rod (30a) tends to move further forward. The arm (36) connected to the mold opening / closing crosshead (35) to which the tip of the male threaded rod (30a) is connected is oriented at right angles to the male threaded rod (30a). The slight advance of the open / close crosshead (35) is hardly affected and there is almost no increase or decrease in the clamping force. On the other hand, the tip of the male screw rod (30a) is connected to the gate cut pin (30) via the intermediate pin (30b) and the pin pressing rod (30c). The cut pin (30) also moves forward to close the gate (2a) of the fixed mold (1b) at its tip. As a result, the mold cavity (2) is completely shut out from the outside in a state in which the resin (3) is filled by the amount that the core mold (5) has retracted.
At the time of the gate cut, the product protruding pin (61a) and the center pin (61b) do not protrude together with the gate cut pin (30), and the tip thereof is kept flush with the cavity surface (5a).
[0024]
Next, the process moves to FIG. When the gate cut is completed as described above, the core opening / closing servo motor (40) is operated again in this state to advance the core mold (5) to the forward limit, and the filling resin (3) is pressed with extremely strong pressure, and the core The fine unevenness of the mold (5) is transferred to the molded product (26) in which the filling resin (3) is cured.
When the curing of the filling resin (3) is completed, as shown in FIG. 6 (6), the core mold control servo motor (40) is reversely operated to separate the core mold (5) from the fixed mold (1b) side.
Next, moving to FIG. 6 (7), the mold control servo motor (31) is reversely operated to separate the movable mold (1a) from the fixed mold (1b) side. At this time, the molded product (26) moves together with the moving mold (1a) while being fitted in the mold cavity (2) of the moving mold (1a).
[0025]
Finally, moving to Fig. 6 (8), when the mold opening is finished, the eject cylinder (60) is operated, the projecting pin (61) is projected, the product projecting pin (61a) and the center pin (61b) And the gate resin (2b) is released, and the molded product (26) is released, and is collected by a product take-out device (not shown).
[0026]
【The invention's effect】
As described above, according to the present invention, since all operations of the injection work are controlled by the servo motor, the timing, injection speed, pressurization speed, pressurization pressure, etc. can be freely controlled. Of course, the transferability of the concave and convex portions to the molded product can be remarkably improved, and since the servo motor can be made to perform a complex operation, the cycle can be increased.
Further, since the toggle mechanism is used as the filling mechanism of the filling resin by the core mold, the core mold can be compressed with almost the same force as the mold clamping force, and the fine unevenness can be accurately transferred.
In addition, since a bearing is used for the rotational connection between the arms constituting the toggle mechanism, the movement of the core type can be made extremely precise and smooth, which is a drawback of the conventional toggle mechanism using a metal sliding bearing. It was possible to eliminate looseness and irregularities in the movement of the rotating connection.
[Brief description of the drawings]
FIG. 1 is a sectional view showing a schematic structure of a main part of an injection molding machine according to the present invention. FIG. 2 is a drawing of a mold mechanism part in FIG. Half is an enlarged sectional view when the mold is opened.
3 is an enlarged cross-sectional view of the mold mechanism portion of FIG. 2 in a state in which the mold is being filled with resin. FIG. 4 is an enlarged cross-sectional view of the mold mechanism portion of FIG. 5 is a detailed enlarged cross-sectional view of the core mold opening / closing toggle mechanism in the mold mechanism portion of FIG. 2. FIG. 6 is a cross-sectional view showing the operating state of the mold in the entire injection process of the present invention. [Explanation of symbols]
(A) ... Injection molding machine (a) ... Injection mechanism (b) ... Mold mechanism
(1) ... Mold
(2) ... Mold cavity
(3)… Resin (3a)… Weighing resin (3b)… Kneaded resin
(4) ... Screw
(5)… Core type
(8)… Control device
(11) (12) (31) (40) ... Servo motor
(30)… Gate cut pin

Claims (3)

An injection molding machine used in a precision core compression injection molding method, in which metering resin is injected into a mold cavity, kneaded resin is metered, a mold is opened and closed, and a core mold disposed in the mold Servo motors are used as drive sources for opening and closing, gate cutting after filling the mold cavity with metering resin, and compression of the filling resin by the core mold after gate cutting . Using a mold opening / closing toggle mechanism that is actuated by advancing or retreating, the tip of the male screw rod is connected to the gate cut pin via an intermediate pin and a pin pressing rod, and the gate cut pin is advanced by advancing the male screw rod. An injection molding machine characterized by closing the gate .   The injection molding machine according to claim 1, wherein a toggle mechanism is used as a compression mechanism of the filling resin by the core mold.   The injection molding machine according to claim 2, wherein a bearing is used for a rotational connection portion between arms constituting the toggle mechanism.

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