JP5380183B2 - Clamping device for injection compression molding machine and injection compression molding device - Google Patents

Description

The present invention will depend on the type ShimeSo location of plasticized molding material plastic material or the like by using a mold clamping control injection compression molding machine for injection compression molding a suitable compression molding machine, and to an injection compression molding apparatus.

In a conventional injection compression molding machine having a plurality of mold clamping cylinders, after a certain amount of plasticized molten resin or the like is injected into a cavity formed between a fixed mold and a movable mold, a plurality of mold clampings are immediately performed. By mold clamping with a cylinder, the mold cavity shape and dimensions are obtained by applying a relatively large mold clamping force to both molds while compressing and extending the resin while the molten resin still remains plastic. Obtaining precise street moldings is done.
When molding a molding material into a molded product having an asymmetric shape using such an injection compression molding machine, the load on each mold clamping cylinder is not uniform because the pressure distribution inside the mold becomes uneven when the mold is compressed. Due to this, a relative inclination occurs between the fixed mold and the movable mold, the fixed mold and the movable mold do not close in parallel, and the thickness of the molded product becomes uneven. was there.

In addition, even in the case of a molded product having a symmetric shape, unevenness in thickness and density may cause defects in product quality, such as a molded product that is transparent and does not like optical distortion, such as lenses and windows. In some cases, precise control of the compression timing that greatly affects the parallelism and compression allowance of the mold and the degree of pressure propagation accompanying the progress of resin cooling is required.
Therefore, when the mold is compressed, regardless of the compression load applied to each mold clamping cylinder, each mold clamping cylinder has the same speed and the resin cooling degree (viscosity increase degree) is low, and the resin pressure propagation It is important that the stroke is quickly performed at a timing with no difference in the degree, and as a result, the movable mold approaches quickly while keeping parallel to the fixed mold, and stops accurately at a predetermined position.
Also, before injecting a certain amount of plasticized molten resin or the like between the fixed mold and the movable mold, a predetermined gap is formed between both molds (this state is hereinafter referred to as “mold opening”). In order to achieve this, precise positioning control of the movable mold is indispensable.

  Patent Document 1 discloses a servo valve mechanism that adjusts a moving speed of a movable part in the plurality of mold clamping cylinders and a hydraulic fluid pressure supplied to the cylinder, and a position detection that detects a position of a movable part in the plurality of mold clamping cylinders. In a mold clamping control device of an injection compression molding machine, comprising: means and fluid pressure detecting means for detecting a working fluid pressure at the time of mold clamping to at least one of the mold clamping cylinders During compression molding of the molded product, pressure control is performed on the specific clamping cylinders in the plurality of clamping cylinders, and the specific clamping cylinders are applied to other clamping cylinders other than the specific clamping cylinders. The invention is an invention in which the servo valve mechanism is controlled so as to translate the movable mold by performing the following speed / position control.

  Patent Document 2 includes a hydraulic cylinder that is connected to a mechanical system that is a control target and whose piston position is controlled by an inflow / outflow amount of hydraulic oil from a servo valve, and a displacement meter that detects a displacement of the control target. In the electro-hydraulic servo control device, the direction is the same as the direction of change of the target value and corresponds to a half period of the natural vibration period of the electro-hydraulic servo control system including the mechanical system with respect to the change of the target value. A correction signal that is generated with a time delay and then becomes zero in a relatively short time is added to the target value, and the speed signal to be controlled is set to a half of the natural vibration period as the correction signal. By using a signal delayed by the time corresponding to the period, it is possible to provide an electric / hydraulic servo control device that can cancel the continuous vibration of the mechanical system and can reach the target value stably and at high speed. There.

  Patent Document 3 discloses a technical disclosure related to a vibration testing machine that can adjust the response of a hydraulic cylinder and expand the applicable frequency range of a vibration test that can be effectively performed. The principle is based on adjusting the spring constant of hydraulic oil, that is, the amount of oil in the cylinder, but a specific structural example for that purpose is presented, and a long stroke test required when the test conditions cannot be limited in advance, A vibration tester having an adjustment function for enabling a high-frequency region test to be performed with the same apparatus is provided.

Japanese Patent No. 3860895 Japanese Examined Patent Publication No. 6-95298 JP-B-2-23819

The technique proposed in Patent Document 1 has a great effect of maintaining the quality of a molded product by securing the parallelism of the mold and performing compression molding safely, but the uniform and low optical distortion is high. As with compression molded products whose characteristics are questioned, advancement of mold positioning control accuracy, which is the basis for further quality improvement, that is, improvement and equalization of positioning accuracy and speed control accuracy of multiple clamping servo control systems Was not able to respond sufficiently.
The reason for this is that pressure control is performed on a specific mold clamping cylinder, but speed / position control that follows the specific mold clamping cylinder is applied to other cylinders other than the specific mold clamping cylinder. Therefore, a time delay occurs in the follow-up control, and an error may occur in the control speed and the control position between the specific mold clamping cylinder and another mold clamping cylinder.

In addition, even in the mold open state before compression molding, injection of the plasticized molten resin or the like into the mold may lead to an error in the mold position or parallelism due to the injection resin pressure. Furthermore, since it is necessary to quickly shift to the compression process, it is necessary to maintain a highly responsive and accurate feedback control throughout the mold opening and compression process period.
Further, the technique proposed in Patent Document 2 requires comparison / calculation based on the detected value to obtain a correction value, and further to perform an operation such as adding the correction value to the target value. In some cases, the improvement of the operation response of the hydraulic cylinder due to the delay of the control signal for the time required for the process reaches its peak.

In addition, the technique proposed in Patent Document 3 is a technique for improving the response of the hydraulic cylinder, but in measuring the correlation between the frequency and the excitation force in a steady state of vibration as a vibration tester, This is a dedicated technology that can improve the long stroke test and the high frequency test so that it can be carried out with the same equipment, and apply it to the actuator of the vibration tester that effectively and efficiently tests the vibration characteristics of various test objects. For machines that require a response, problems such as a decrease in responsiveness occur.
That is, the technique proposed in Patent Document 3 makes it possible to increase the resonance frequency by reducing the volume in the main cylinder by the advancement of the subcylinder. Is held by the hydraulic pressure applied before and after the sub-cylinder and is not completely fixed (rigid body).

That is, since oil has a relatively large compressibility compared with a rigid body, when a large driving pressure is applied to the front side of the sub cylinder (piston side) at a high speed at the start of piston operation, the sub cylinder is The oil filling the back side is also instantaneously compressed and the sub cylinder moves to the back side, so that the drive hydraulic pressure applied to the front side of the sub cylinder is instantaneously It is absorbed and a delay occurs in the rise of hydraulic pressure.
Therefore, electric / hydraulic servo control that is simple (low cost) suitable for injection compression molding machine, has high positioning / speed control accuracy, high responsiveness, and high-speed fine feedback control. It is necessary to invent a mold clamping control system for an injection compression molding machine.

ここで、Ｋ：作動油弾性、 Ｍ：被駆動質量、 Ａ：シリンダ断面積
Ｖ：シリンダ容積
である。 Specifically, FIG. 1 shows the structure of a mold clamping device of an injection molding machine. The position and speed of the total mass M of driven parts (movable mold plate, mold, tie rod gripping device, etc.) are hydraulically determined. In the case of control, the limit of the control performance is higher as the time until the hydraulic driving force is transmitted to the driven mass M is shorter. Generally, hydraulic oil has low rigidity and slow force transmission compared with other metal parts of the fuselage, so that the hydraulic actuator cannot respond to fast hydraulic oil pressure changes. That is, when the control frequency is increased in order to increase the accuracy of the feedback control (when the change speed of the hydraulic pressure is increased), a frequency region (response limit) in which the response of the hydraulic cylinder rapidly decreases occurs. The sudden drop in response is due to the resonance of oil in the hydraulic actuator due to the control frequency. When the oil in the hydraulic actuator resonates, the oil pressure increase / decrease synchronized with the control frequency is synchronized with the oil compression / expansion, and even if the oil pressure increases / decreases, it is absorbed by the oil compression / expansion. An uncontrollable phenomenon will occur.
The response limit of the hydraulic cylinder is given by the following equation (a) as the oil column resonance frequency f.

Here, K: hydraulic oil elasticity, M: driven mass, A: cylinder cross-sectional area
V: cylinder volume.

となると考えられる。
ただし、Ｌ１＋Ｌ２＝Ｃであり、Ｃ：シリンダストローク長さで一定数である。
通常のシリンダの場合、Ａ１＝Ａ２と見なし得るので、前記数式は、

と変形できるが、Ｌ１をＣに対して相当に小さく選定すれば、

と見なし得るから、

となる。 In the case of the hydraulic control model of the mold clamping device shown in FIG. 1, the above equation (a) is expressed as V1 = V1 = L1 and L2 as the oil chamber cross-sectional areas on both sides of the piston and L1 and L2, respectively. Since A1 × L1 and V2 = A2 × L2,

It is thought that it becomes.
However, L1 + L2 = C, and C: a fixed number of cylinder stroke lengths.
In the case of a normal cylinder, it can be considered that A1 = A2, so the above equation is

However, if L1 is selected to be considerably smaller than C,

Can be considered

It becomes.

  According to the formula (b) above, if the elasticity K of the hydraulic oil is a given value, in order to increase the oil column resonance frequency, the driven mass M is decreased or the cylinder bore A is increased. It is necessary to increase the effective area or shorten the length L1 of the oil column. However, it is often not easy to reduce the mass M for the purpose of maintaining the mechanical strength. Further, when the effective sectional area A of the cylinder is increased, the flow rate of the hydraulic oil increases, so that both the capacity of the servo valve and the capacity of the hydraulic pump must be increased more than necessary, which is wasted. Further, when the effective sectional area A of the cylinder is increased, the flow rate of the hydraulic oil increases, so that both the capacity of the servo valve and the capacity of the hydraulic pump must be increased more than necessary, which is wasted.

  The present invention provides a highly responsive hydraulic cylinder control system in injection compression molding, and applies the system to each mold clamping control device to apply smooth and highly accurate control, thereby achieving high response. By providing injection compression control, an object is to enable compression molding of a high-quality molded product such as no harmful optical distortion in the molded product.

In order to solve the above problems, the present invention aims to solve the problem by the following means.
(1) injection compression molding machine of the first means, between a pair of molds composed of a fixed mold and the movable mold, compression molding by a plurality of mold clamping cylinder housing the molding material plasticized injection In a mold clamping device of a compression molding machine , a working fluid pressure source for supplying a working fluid, and a displacement and a moving speed of a movable part in each of the plurality of mold clamping cylinders upon receiving the working fluid from the working fluid pressure source And a servo valve mechanism for adjusting the hydraulic fluid pressure supplied to the plurality of mold clamping cylinders, position detecting means for detecting the position of the piston head in each of the plurality of mold clamping cylinders, and applied to the mold clamping cylinders And a control device that performs feedback control of the servo valve mechanism using a control frequency having a cycle time equal to or longer than a limit time until the driving force is transmitted to the driven mass. The distance L1 between the cylinder and the end face of the cylinder is L1 << C with respect to the entire stroke C of the mold clamping cylinder, the oil column resonance frequency f is the elasticity of the working fluid K, and the mold clamping cylinder When the cross-sectional area of the A1, the driven mass which is driven by the mold clamping cylinder is M, is the value that satisfies the following shows the equation (b), wherein the control device, the compression operation start out morphism, the servo valve mechanism by adjusting the position of each piston head of said plurality of mold clamping cylinder, the piston head and the distance L1 between the end face of the compression side of the cylinder, the oil column resonance of the compression side oil chamber of the plurality of mold clamping cylinder frequency and high becomes the predetermined boundary distance L b which the working fluid does not resonate in the compression side oil chamber to the control frequency, the predetermined boundary distance Lb is, when the clamping cylinder inner diameter phi, the following (c) satisfy the equation And features.

In general, there are design restrictions depending on the equipment, so it cannot usually be shortened arbitrarily. Even in an injection molding machine, there are processes that require a large stroke as the stroke value of the hydraulic cylinder for clamping in one cycle, and it is often impossible to reduce the dimension value of the hydraulic cylinder. In the required mold opening process and compression molding process, the operation stroke of the hydraulic cylinder can be limited to several mm to several tens of mm. Therefore, by limiting the position of the piston so that the distance L between the piston head and the end face of the hydraulic cylinder is shortened only in the mold opening process and compression molding process that require high response, the hydraulic pressure in the process is reduced. The response limit of the cylinder can be increased.
As described above, in the mold opening process and the compression molding process, the response limit at which resonance occurs due to the control frequency can be made sufficiently high with respect to the control frequency, thereby preventing a decrease in the response of the hydraulic cylinder. it can.

( 2 ) The injection compression molding machine of the second means is characterized in that, in the mold clamping cylinder of the (1) injection compression molding machine, the predetermined boundary distance Lb further satisfies the formula (d) .

If the distance L1 between the piston head and the end face of the hydraulic cylinder is made extremely short, the flow path of the hydraulic oil becomes narrow, so the vertical flow of the hydraulic oil toward the discharge port becomes dominant, and the moving direction of the piston (Axial direction) Interference with the flow causes turbulence in the oil chamber, accompanied by a large pressure loss that impairs the function as a hydraulic actuator, and requires a very large hydraulic source pressure. Further, if the distance L1 is increased, the control position accuracy is degraded.
On the other hand, the pressure loss can be suppressed and the control position accuracy can be maintained with high accuracy by setting the boundary distance Lb to a value in the range as described later in the present invention.

( 3 ) The third means of the injection compression molding machine is such that the plurality of clamping cylinders of (1) to ( 2 ) are provided at at least four corners of a fixed mold plate or a movable mold plate. A molding machine, wherein the mold clamping devices are controlled by injection compression so as to increase the parallelism between mold plates independently of each other.
( 4 ) In the fourth aspect of the injection compression molding machine, the injection compression control in the mold clamping device of ( 3 ) is carried out with the distance between the hydraulic piston head end face and the hydraulic cylinder wall surface being a predetermined distance Lb. It is characterized by performing.

( 5 ) A fifth means of the injection compression molding machine includes the tie bar gripping device in which the mold clamping device of ( 3 ) or ( 4 ) opens or closes the split nut to release or restrain the thread on the outer surface of the tie bar. A mold clamping device, wherein when the distance between the end surface of the hydraulic piston head and the wall surface of the hydraulic cylinder reaches the boundary distance, the movable nut is securely meshed with the crests of the thread of the split nut and the tie bar. An adjustment member for adjusting a relative position between the split nut and the tie bar is provided so that the mold can be gripped.

The present invention according to claim 1 and claim 4 is applicable to a plurality of mold clamping devices of an injection compression molding machine, thereby enabling accurate mold opening and highly responsive compression molding, and optical distortion. It is possible to produce a suppressed molded product. In addition, since high-response injection compression is possible, injection compression can be started in a state where the resin is highly plastic and sufficiently high in temperature. There exists an effect which provides the injection compression molding machine which can be prevented.
The present invention according to claim 2, claim 3 and claim 5 further does not require any special structural change to the hydraulic cylinder in the mold clamping device of the injection compression molding machine, and maintains the conventional dimensional structure, However, there is an effect of providing an injection compression molding machine capable of producing a high-quality molded product by giving conditions for performing high-response and accurate feedback control according to the position of the piston.
According to the sixth aspect of the present invention, even when the split nut method is applied to the tie bar gripping device of the injection molding machine, the gripping of the movable mold by the engagement of the threads of the split nut and the tie bar is ensured. effective.

FIG. 3 is a schematic cross-sectional view showing a hydraulic control model related to a set of mold clamping devices displayed in a region surrounded by a partition line D of the injection compression molding machine shown in FIG. 2. It is a longitudinal cross-sectional view which fractures | ruptures a part of injection compression molding machine concerning 1st Embodiment of this invention, and shows the structure typically. It is a longitudinal cross-sectional view which fractures | ruptures a part of mold clamping apparatus of the injection compression molding machine which concerns on 2nd Embodiment of this invention, and shows the structure typically.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art or that are substantially the same.
(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic cross-sectional view showing a hydraulic control model related to a set of mold clamping devices displayed in a region surrounded by a partition line D of the injection compression molding machine shown in FIG.
FIG. 2 is a longitudinal sectional view schematically showing the structure of a part of an injection compression molding machine according to the present invention, with a part thereof broken.

As shown in FIGS. 1 and 2, the mold clamping control device of the injection compression molding machine includes a fixed mold platen 5 fixed to one end side portion (see the right side portion in FIG. 2) of the upper surface of the support frame 1. The fixed mold 3 is attached to the fixed mold platen 5. Further, a mold plate slide mechanism is provided so that the movable mold plate 9 to which the movable mold 7 is attached is opposed to the other end portion (see the left portion in FIG. 2) of the upper surface of the support frame 1. 30.
That is, the template slide mechanism 30 includes a rail 39, a linear bearing 35, and a table 37. The movable template 9 is placed on the table 37. The table 37 is fixed on the upper surface of the support frame 1. The rail 39 is guided through the linear bearing 35, so that the movable platen 9 is slidably mounted on the support frame 1.

Further, a plurality of (four in this embodiment) mold clamping cylinders 11a to 11d (however, the mold clamping cylinders 11c and 11d are not shown) are required in the vicinity of the outer periphery of the fixed mold platen 5 with a small stroke and a large sectional area. The pistons 13a to 13d are slidably inserted in the mold clamping cylinders 11a to 11d in the moving direction of the movable mold platen 9, and the pistons 13a to 13d are The proximal ends of the tie bars 15a to 15d are connected. Moreover, each tie bar 15a-15d is extended horizontally toward the movable mold board 9 side.
In this embodiment as well, each symbol having the characters c and d displayed with parentheses in the figure has the same cross-sectional shape as each symbol having the characters a and b. It shows that it is provided, and that it is arranged at a different position in the thickness direction of the paper. For example, the mold clamping cylinder 11c is indicated as “11a (11c)” in FIG. 2. This mold clamping cylinder 11c has the same cross-sectional shape as the mold clamping cylinder 11a, and the mold clamping cylinder 11a. It is shown that they are disposed at different positions in the thickness direction of the paper.

Also in this embodiment, each code having characters a to d in the figure indicates that there is a corresponding relationship between the codes having the same character. For example, in the above-described configuration, In the mold clamping cylinder 11a, the piston 13a is inserted and the base end side of the tie bar 15a is connected to the piston 13a. Similarly, the piston 13b is inserted in the mold clamping cylinder 11b. In addition, it is shown that the base end side of the tie bar 15b is connected to the piston 13b. Similarly, the symbols having the letters a to d are portions corresponding to each other. Indicates.
Further, for the sake of convenience, the parts having the characters c and d are not shown.

Further, in the parts having the symbols a to d described above, for the sake of convenience, the symbols a to d are hereinafter referred to as those having no structural and functional differences between the components having the symbols a to d. May be omitted. For example, the tie bars 15a to 15d have the same configuration and the same function, and hereinafter, the tie bar 15 is represented by the tie bars indicated by reference numerals 15a to 15d.
These tie bars 15 pass through the respective insertion holes 27 formed in the movable mold platen 9, and are attached to the movable mold plate 9 on the outer periphery in the vicinity of the end portions of the tie bars 15. A processing surface 28 such as an engagement groove is provided so that the gripping surface of the tie bar gripping device 29 is tightly engaged and firmly gripped.

Each tie bar gripping device 29 is engaged with or released from the processing surface 28 formed on each tie bar 15 and is provided so as to open and close in a direction substantially perpendicular to the axial direction of the insertion hole 27. These are opened and closed by a hydraulic cylinder or the like (not shown).
Further, a support member 33 is fixed to the mounting surface side of the tie bar gripping device 29 attached to the movable platen 9, and the support member 33 closes the tie bar 15 by closing the tie bar gripping device 29. In this state, hydraulic pressure acts on the oil chamber on the head side of the piston 13 (the right side of each piston 13 in FIGS. 1 and 2), and the tie bar 15 is pressed in the mold opening direction (left direction in FIGS. 1 and 2). At this time, the tie bar gripping device 29 is supported, and the movable mold platen 9 and the movable mold 7 are moved as the tie bar 15 moves.

On the other hand, the base end sides of the rods 53a to 53d are connected to the end surfaces of the pistons 13a to 13d sliding in the mold clamping cylinders 11a to 11d on the side where the tie bars 15a to 15d are not connected. The rods 53a to 53d extend horizontally in the direction opposite to the tie bars 15a to 15d. Each of the rods 53a to 53d passes through the fixed mold platen 5, and position sensors 55a to 55d are disposed at the tip portions thereof.
Scales 57a to 57d having detection graduations or detection graduation magnets are arranged in parallel with the rods 53a to 53d at positions near the rods 53a to 53d in the fixed mold platen 5, and these scales 57a to 57d. And position sensors 55a to 55d cooperate to function as position detecting means. That is, the scales 57a to 57d and the position sensors 55a to 55d detect the positions of the pistons 13a to 13d in the mold clamping cylinders 11a to 11d, and the positions of the pistons 13 in the mold clamping cylinders 11 (movable part positions). ) Can be detected.

Furthermore, a moving cylinder 17 is fixed to the lower part of the fixed mold platen 5 (see FIG. 2), and the tip of the moving rod 20 connected to the internal piston 18 of the moving cylinder 17 is the lower part of the movable mold platen 9. It is connected and fixed to. The moving cylinder 17 can be replaced with an electric drive actuator such as a ball screw. The movable mold plate 9 and the movable mold 7 follow the movement of the internal piston 18 of the moving cylinder 17 and are guided to the rail 39 on the support frame 1 through the base 37 of the mold plate slide mechanism 30 and the linear bearing 35. In the end, the insertion hole 27 formed in the movable mold plate 9 is fitted into the tie bar 15 extending in parallel with the rail 39 from the fixed mold plate 5 (see FIG. 2).
Normally, when the movable mold 7 is exchanged or inspected / repaired, the movable mold plate 9 and the movable mold 7 are both in the position of the maximum stroke in both the piston 18 and the movable rod 20 of the movable cylinder 17 (see FIG. 2). The tie bar gripping device 29 is open because the insertion hole 27 formed in the tie bar 15 and the movable mold plate 9 is not in contact.

On the other hand, the piston 13 in the mold clamping cylinder 11 provided in the fixed mold platen 5 is brought close to the left end of the cylinder so that the tie bar 15 protrudes the longest toward the movable mold platen side. The position where the insertion hole 27 formed in the board 9 is fitted to the extended tie bar 15 is temporarily set to a position where the molded product is taken out (a position where the mold is opened), and then the tie bar gripping device 29 is closed and movable. If the mold platen 9 and the tie bar 15 are connected, the subsequent mold closing process and mold opening process can all be performed by positioning control of the mold clamping device.
In the description of the embodiment of the present invention, how the hydraulic control model according to the set of mold clamping devices shown in FIG. 1 enables accurate positioning control and highly responsive pressure / speed control. By explaining in detail below, it will be explained that the four sets of mold clamping devices provided in the injection compression molding machine can perform injection compression control independently of each other and to increase the parallelism between the mold plates.

FIG. 1 is a schematic cross-sectional view showing an apparatus configuration relating to one set of mold clamping devices in four sets of mold clamping devices provided in the injection compression molding machine shown in FIG.
FIG. 1 shows that the tie bar 15 a is connected to the movable mold platen 9 and the movable mold 7 by the tie bar gripping device 29, and the tie bar base is driven by the hydraulic pressure loaded from the working fluid pressure source 80 via the servo valve 60. The tie bar 15 moves to the back side (right side in the figure) of the piston 13a at the end, and the plasticized resin injected from the injection unit 19 is compressed into a cavity formed between the fixed mold 5 and the movable mold 7. The state which is shape | molding is shown. However, an electronic control unit for controlling the servo valve 60 is not shown.
In the case of this electronic / hydraulic control, the limit time until the hydraulic driving force applied to the mold clamping cylinder 11a is transmitted to the driven mass M is verified, and a control frequency having a cycle time as short as possible is used. In addition, feedback control with a high control density improves the accuracy and responsiveness of the position / speed control of the tie bar 15, that is, the movable mold 7.

The response limit of the hydraulic cylinder is given by the equation (a) as the oil column resonance frequency f (the limit time until the transmission is 1 / f), but in the case of FIG. 1, the equation (b) is applied. it can. Tables 1 and 2 show examples of results obtained by the inventor verifying the relationship of this equation through tests.
Table 1 shows the test results at a cylinder diameter φ = 850 mm, and Table 2 shows the test results at a cylinder diameter φ = 400 mm. The piston position L1 (mm), which is the distance between the piston head and the cylinder wall surface, is displayed on the uppermost stage, and the oil column resonance frequency f (Hz) and the control frequency (Hz) at which stable feedback control is obtained in that order. Following the operation time constant (ms) and position control error (mm), the cylinder hydraulic oil pressure loss (kPa) is displayed at the bottom.

In the mold clamping apparatus, since the upper limit of accuracy error, which is said to be high-accuracy position control, is ± 0.05 mm, in the case of Table 1, it is desirable that the piston position L1 does not exceed 10 mm. In addition, since the hydraulic pressure loss (kPa) in the cylinder at the lowest stage increases rapidly and the required hydraulic pressure rises, in the region where the piston position L1 is less than 5 mm, the margin of the supply source hydraulic pressure with respect to the piston driving hydraulic pressure is sharp. This is not preferable. Eventually, it is shown that the condition within the thick line frame in which the piston position L1 is 5 mm ≦ L1 ≦ 10 mm is effective for the feedback control.
Similarly, it can be seen from Table 2 that when the cylinder diameter φ = 400 mm, the condition within the thick line frame in which the piston position L1 is 3 mm ≦ L1 ≦ 5 mm is effective.

但し、十分高い油圧を供給可能な油圧源を有する油圧回路を使用し、シリンダ内作動油の圧力損失を考慮する必要のない場合は、境界距離Ｌｂは、下記（ｃ）式で示される値でも良い。

In addition to the case where the inner diameter φ of the hydraulic cylinder is 850 mm and φ = 400 mm, when tests are performed with hydraulic cylinders of various sizes, the upper limit value and the lower limit value of the boundary distance Lb that is the optimum piston position are The value of the range of the boundary distance Lb that is proportional to the square root, has high responsiveness and high speed / position control accuracy, and satisfies both practical hydraulic values, It has been found that it is most preferable for obtaining high productivity.

However, when a hydraulic circuit having a hydraulic source capable of supplying a sufficiently high hydraulic pressure is used and it is not necessary to consider the pressure loss of the hydraulic oil in the cylinder, the boundary distance Lb is a value expressed by the following equation (c). good.

A method for setting a mold clamping device for performing feedback control on the hydraulic cylinder within the boundary distance to execute mold opening and compression molding will be described below.
(Setting of mold platen position of mold clamping device)
In FIG. 2, after the tie bar gripping device 29 is closed and the movable mold platen 9 and the tie bar 15 are connected, the process proceeds to a mold closing process, and the fixed mold 4 and the movable mold 7 are brought into close contact with each other. Next, the servo valve 60 is operated while referring to the scale 57, and the piston 13, the movable mold platen 9 and the movable metal plate are moved so that the distance L1 between the piston 13 and the end face of the cylinder becomes a predetermined value (for example, 5 mm). The mold 7 is moved integrally in the mold opening direction (left side in the figure) to open the mold.
In the present embodiment, an example is shown in which the piston 13, the movable mold plate 9, and the movable mold 7 are integrally moved so that the distance L1 between the piston 13 and the end face of the cylinder is 5 mm through the mold closing process. However, the origin position of the piston 13 is stored in advance in a control device (not shown), and the distance L1 between the piston 13 and the end face of the cylinder is determined by referring to the scale 57 without going through the mold closing process. The movement may be controlled so as to be 5 mm.
In the step of opening the mold, it is better to control so that the parallelism of the movable mold platen and the fixed mold platen is kept high.

(Injection of plasticized molten resin)
When the mold opening is controlled and maintained, and the temperature distribution of both molds 3 and 7 reaches a predetermined accuracy, the injection unit 19 uses the uniformly melted plasticized resin R held inside the nozzle And injected into the mold cavity (see arrow in Fig. 1). At this time, since a considerable injection pressure is applied to the cavity, the movable mold 7 receives an unequal force in the left direction, but the mold clamping device is subjected to accurate positioning feedback control, and a predetermined mold Maintains an open position and position.

(Compression molding)
The injected molten resin R is appropriately cooled by both molds, but the compression molding process is quickly started while sufficient plasticity remains in the entire lump of the resin. At this time, the distance L1 between the piston head and the cylinder end face is 5 mm, and it is within the condition of 5 mm ≦ Lb ≦ 10 mm that can control with high responsiveness and position / speed accuracy.
Therefore, if a mold clamping control device (not shown) gives a hydraulic driving force having a high control density by feedback control to the mold clamping cylinder 11 via the servo valve 60, the piston 13, the tie bar 15, the movable mold plate 9, the movable mold 7 will be described. Etc. are ready to achieve the objectives of the present invention.

The above control with high responsiveness and position / speed accuracy is performed by each mold clamping device of the injection compression molding machine composed of 4 sets so as to increase the parallelism between the molds independently of each other. Therefore, a molded product having a uniform thickness can be obtained.
In this embodiment, the boundary distance is 5 mm ≦ Lb ≦ 10 mm when the cylinder diameter φ = 850 mm. However, even when the cylinder diameter φ is different, the boundary distance Lb is set according to the equation (d). The highest effect of the invention can be obtained. For example, when the cylinder diameter φ = 400 mm, the boundary distance Lb may be determined so that the value of the equation (d) satisfies 2.5 mm ≦ Lb ≦ 6.5 mm.

(Open mold and take out molded product)
When the predetermined time has elapsed and cooling and solidification of the molded product is completed, hydraulic oil having a rated flow rate is supplied to the clamping cylinder 11 via the servo valve 60, and the piston 13, the tie bar 15, the movable mold plate 9, and the movable mold. 7 etc. are moved at high speed in the left direction in the figure, and stop at a preset molded product take-out position.
Thereafter, an ejector (not shown) provided on the movable mold platen 9 operates to push out and remove the molded product from the movable mold. Then, the process proceeds to the next cycle.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG.
FIG. 3 is a longitudinal sectional view schematically showing the structure of a part of a mold clamping device of an injection compression molding machine according to a second embodiment of the present invention, and is a view corresponding to FIG. is there. In FIG. 3, the same structure as that of the first embodiment is denoted by the same symbol, and redundant description is omitted.
When the tie bar gripping device adopts a system in which the split nut 129 is opened or closed to release or restrain the thread 128 on the outer surface of the tie bar, the split nut 129 cannot be engaged or gripped except at the pitch interval of the thread 128. Therefore, as described in detail in the above section (Settings before production of the mold clamping device), the tie bar is provided even when the distance between the end surface of the hydraulic piston head and the wall surface of the hydraulic cylinder reaches the boundary distance (Lb = 5 mm). There are cases where it is not possible to engage and grip. In such a case, an adjustment member for finely adjusting the threading position of the tie bar 128 and the groove of the split nut 129 is used between the movable mold platen and the mold, and the groove is engaged with the mold. To do. In this embodiment, the spacer 8 is shown as the adjustment member, but the adjustment member may be a member that can change the relative distance between the tie bar gripping device and the movable mold plate, for example, a screw structure.

DESCRIPTION OF SYMBOLS 1 Support frame 3 Fixed mold 5 Fixed mold board 7 Movable mold 8 Spacer 9 Movable mold board 11; Clamping cylinder 11a (11c) Clamping cylinder 11b (11d) Clamping cylinder 13; Piston 13a (13c) Piston 15; Tie bar 15a (15c) Tie bar 15b (15d) Tie bar 17 Moving cylinder 18 Internal piston 19 Injection unit 20 Moving rod 27 Insertion hole 28 Tie bar outer peripheral machining surface 29 Tie bar gripping device 30 Mold plate slide mechanism 33 Support member 35 Linear bearing 37 Base 39 Rail 41 Position sensor 53a (53c) Rod 55a (55c) Position sensor 57a (57c) Scale 60 Servo valve 80 Working fluid pressure source 109 Movable mold plate 115; Tie bar 115a (115c) Tie bar 115b (115d) Tie bar 127 Insertion hole
128 Screw 129 Split nut D Dividing line R Molten resin F / B Feedback Lb Piston head boundary distances L1, L2 Oil chamber length A, _{１ 1} , A ₂ Piston pressure receiving area φ Hydraulic cylinder diameter

Claims (7)

In a mold clamping device of an injection compression molding machine in which a plasticized molding material is accommodated between a pair of molds composed of a fixed mold and a movable mold and compression molded by a plurality of mold clamping cylinders.
A working fluid pressure source for supplying the working fluid;
A servo valve mechanism that receives the working fluid from the working fluid pressure source and adjusts the displacement and moving speed of the movable part of each of the plurality of mold clamping cylinders and the supply working fluid pressure to the plurality of mold clamping cylinders. When,
Position detecting means for detecting the position of the piston head in each of the plurality of mold clamping cylinders;
A control device that performs a feedback control of the servo valve mechanism using a control frequency having a cycle time equal to or longer than a limit time until the driving force applied to the mold clamping cylinder is transmitted to the driven mass;
The distance L1 between the piston head and the end face of the cylinder on the compression side is L1 << C with respect to the entire stroke C of the clamping cylinder,
The oil column resonance frequency f is
When the elasticity of the working fluid is K, the sectional area of the clamping cylinder is A1, and the driven mass driven by the clamping cylinder is M, the following equation (b) is satisfied:
The controller is
During compression operation starts out morphism, wherein the servo valve mechanism to adjust the position of each piston head of said plurality of mold clamping cylinder, the distance L1 between the end face of the piston head and the compression side of the cylinder, a plurality of mold oil column resonance frequency of the compression side oil chamber of the clamping cylinder is a predetermined boundary distance L b which the working fluid does not resonate in higher becomes the compression side oil chamber to the control frequency,
The predetermined boundary distance Lb satisfies the following expression (c) when the inner diameter of the clamping cylinder is φ, and is a mold clamping device for an injection compression molding machine.

The mold clamping apparatus for an injection compression molding machine according to claim 1, wherein the predetermined boundary distance Lb further satisfies the expression (d) .

Comprising a mold clamping device according to claim 1 or claim 2, wherein the plurality of Katachishime plurality of positions of cylinders fixed mold platen or the movable mold platen, a injection compression molding machine provided on at least four corners, the type An injection compression molding apparatus that controls injection compression so as to increase the parallelism between mold plates independently of each other. Injection compression control in the mold clamping device, before the distance L1 between the Kipi Stone head with the end face of the sheet Linda compression side injection according to claim 3 for injection compression control at a predetermined boundary distance Lb Compression molding device. The mold clamping apparatus, a mold clamping apparatus provided with a tie bar gripping device for releasing or restraining the thread of the open or closed by tie outer surface of the split nut, the end face of the sheet Linda before Kipi piston head and the compression side The split nut and the tie bar so that they can be securely engaged with each other and the movable mold can be gripped when the distance L1 between them reaches the boundary distance Lb. injection compression forming KatachiSo location according to claim 3 or 4, characterized in that an adjustment member for adjusting the relative position of the tie bars. Comprising a mold clamping device according to claim 1 or claim 2, injection compression control in the mold clamping device, before the distance L1 between the Kipi Stone head with the end face of the sheet Linda compression side, predetermined An injection compression molding apparatus that performs injection compression control at a boundary distance Lb. 3. The mold clamping device according to claim 1 or 2, wherein the mold clamping device comprises a tie bar gripping device that opens or closes the split nut to release or restrain the thread on the outer surface of the tie bar. Te, and before when the distance L1 between the Kipi Stone head with the end face of the sheet cylinder on the compression side has reached the boundary distance Lb, thereby reliably engaging the peaks and valleys of the threads of the said split nut tie bar An injection compression molding apparatus comprising an adjusting member for adjusting a relative position between the split nut and the tie bar so that the movable mold can be gripped.

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