JP3154382B2 - Injection compression molding method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a mold in which a molten resin is filled in a mold in a state where the toggle mechanism is not fully extended, and the mold is slightly opened by the filled resin pressure, and then the toggle mechanism is fully extended on the mold clamping side. TECHNICAL FIELD The present invention relates to an injection compression molding method and apparatus for performing compression in a compressed state.

[0002]

2. Description of the Related Art When performing injection compression molding using an injection molding apparatus that performs mold clamping by a toggle mechanism, (1) mold clamping is completed in a state where the toggle mechanism is fully extended, and in this state, a predetermined amount is applied to a mold. Keep a gap.
Then, after the molten resin is injected and filled into the mold, compression is performed by a hydraulic cylinder dedicated to compression or the like separately provided on a movable platen or a fixed platen.

(2) In a toggle-type mold clamping mechanism, a predetermined clearance is ensured in a mold while the toggle mechanism is not fully extended, or a relatively small mold clamping force equal to or less than the maximum mold clamping force. The toggle mechanism is controlled by the control based on the set value converted to the position of the crosshead using the geometric relationship between the crosshead position of the toggle mechanism and the displacement amount of the movable platen (mold opening amount, mold clamping force). After stopping the mold and performing mold clamping, the mold is injected and filled with a molten resin, and then the toggle mechanism is re-driven so as to be fully extended and compressed.

[0004]

The conventional injection compression molding has the following problems. First, (1) In the method in which the mold clamping is completed with the toggle mechanism fully extended and the molten resin is injected and filled in the mold in this state, no special modification is required on the toggle mechanism side. In addition to a toggle mechanism, a dedicated hydraulic cylinder or the like for compression is required, which leads to an increase in complexity and cost of the molding machine. It is difficult to set an appropriate value of the mold opening amount, and further, it needs consistency with the setting of the compression start timing. Also, considering that the injection side and the compression side need to be controlled synchronously, as the drive unit becomes larger, sophistication is required from the software and hardware aspects of the control, which is complicated, and the molding operability is increased. Is significantly reduced.

(2) Due to the geometric relationship of the toggle mechanism,
In the method of controlling the mold clamping with a set value obtained by converting the mold opening amount and the mold clamping force into the crosshead position, the toggle mechanism does not require a hydraulic cylinder dedicated to compression separately from the toggle mechanism as in the above (1). The geometric relationship between the crosshead position and the displacement of the movable platen, in other words, the mold opening and the mold clamping force, depends on the mold thickness set value and the size of the mold according to the thickness of the mold to be installed. The relational expression exists infinitely depending on the combination of die height adjustment values that increase or decrease the maximum generated mold clamping force at the completion of mold clamping.Therefore, it must be calculated based on the geometric relationship for each mold used, and operability Is extremely bad and impractical.

If a geometrical relationship of the toggle mechanism is programmed and a means for performing an automatic calculation process is incorporated to obtain a desired result by a calculation process of the number of combinations of various variables near infinity, a software -There is a problem that the hardware is complicated and large, inevitably leads to high costs and is not appropriate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to control only the injection pressure and the mold clamping force without significantly modifying the existing molding machine of the toggle mechanism. The purpose of the present invention is to provide a stable and continuous supply of non-defective products by simple control without being affected by fluctuations in molding conditions during molding.

[0008]

In order to achieve the above object, the first invention according to the present invention uses a toggle mechanism for performing mold clamping by driving with a hydraulic mold clamping cylinder, and uses the toggle mechanism during the injection filling process. The injection mechanism controls in advance the cooling solidification shrinkage of the resin, controls the injection pressure with the injection pressure that can fill the mold with the amount of resin to which this shrinkage has been added, and the mold clamping mechanism controls the toggle. A mold clamping force that allows the mold to open by extending the tie bar to the mold opening amount corresponding to the amount of the resin that has cooled and solidified by the pressure of the resin filled in the mold cavity in a state where the mechanism is not fully extended. Is added to the mold in advance, and after detecting the completion of the injection filling, the toggle mechanism is extended from an arbitrary point to increase the mold clamping force. In the second invention, the injection pressure control is performed by injection filling. Fire from start Constant pressure that can be filled with up to completion of filling
The pressure was controlled so that the amount of shrinkage did not remain.

In the third aspect of the present invention, a mold clamping force previously applied to the mold is detected by using a mold clamping force detecting unit incorporated in a tie bar, and a detection signal from the mold clamping force detecting unit is detected. When the stroke of the mold clamping cylinder connected to the toggle mechanism when the set mold clamping force is reached is detected, the hydraulic pressure of the mold clamping cylinder is controlled so as to maintain its position. Is defined as a point in time when the injection driving force of the injection mechanism suddenly starts to increase, and the pressurization of the mold clamping force is started based on a time-out signal of a timer activated by the change in the injection driving force.

Further, in the fifth invention, the injection filling is completed when the movement of the injection drive unit of the injection mechanism is stopped, and based on a time-out signal of a timer started from the stop position of the injection drive unit, the mold clamping force is reduced. According to a sixth aspect of the present invention, the pressure increase is started, and the injection control unit includes an injection filling amount setting unit and an injection pressure setting unit, and performs injection filling based on the set values set by the two setting units. A mold clamping force setting unit that sets a mold clamping force that allows the mold to open by extending the tie bar to a mold opening amount corresponding to the cooling solidification shrinkage amount of the resin by the injection filling, and a stroke of the mold clamping cylinder. A mold clamping cylinder stroke sensor for detecting, and a mold clamping force detecting unit incorporated in the tie bar for detecting the mold clamping force in the mold clamping process, and detects the set value of the mold clamping force setting means and the mold clamping force detecting unit. signal In addition to having a mold-clamping control unit that controls the stroke of the mold-clamping cylinder connecting the toggle mechanism to perform mold-clamping, when the injection driving force of the injection mechanism starts to increase sharply, or An injection filling completion detection unit that generates an injection filling completion signal when the movement of the unit stops, a timer that starts based on a detection signal from the injection filling completion detection unit, and a mold clamping pressure increase start time in the compression process are set. And a comparison control unit that compares the set value of the time setting unit with a time-out signal of the timer and generates a pressure increase signal to the mold clamping control unit.

[0011]

In the injection filling process, the filling is controlled so that the filling can be performed at a high speed in the initial stage of filling because the flow resistance of the resin in the mold cavity is small, and in the latter stage of the filling, the flow resistance of the resin increases so that the filling speed is increased. Is naturally decelerated, so that the resin has a continuous speed gradient automatically during resin filling, and can be an ideal natural filling flow (natural flow) that does not generate pack pressure. In addition, the toggle mechanism is extended by filling the amount of resin plus the amount of cooling solidification shrinkage of the resin and by setting the mold clamping force to allow the mold opening amount corresponding to the amount of cooling solidification shrinkage by extending the tie bar. Since the state is one step before, the movable platen does not retreat due to the injection filling pressure of the molten resin due to the boosting characteristic of the toggle mechanism. Furthermore, even when the injection filling is completed, the resin is almost completely filled (just pack) into the mold, and therefore is completely affected by the occurrence of defects such as flow marks due to the discontinuity of the resin flow velocity in the mold. Absent.

Further, since the mold clamping force is detected by the mold clamping force detector incorporated in the tie bar, a highly accurate mold clamping force can be directly detected without any influence from the setting of the mold thickness and the adjustment of the die height. Even during injection filling and when switching the compression process, the mold is given an appropriate mold clamping force, so even if the molding conditions fluctuate during molding, the mold clamping force, that is, the elongation behavior of the tie bar, It has the flexibility to work as an elastic action. In the compression step, since the mold clamping pressure is increased after the completion of the injection filling is detected, the interlocking between the injection side and the mold clamping side can be avoided, so that the molding machine does not need to be upsized. In addition, when the mold clamping pressure is changed over, the compression action corresponding to the cooling, solidification and shrinkage of the resin until just before the pressure increase is switched by the action of the elastic recovery force of the tie bar that has been extended by injection filling due to the addition of the appropriate mold clamping force that was initially set. , The complicated and sophisticated timing control of the conventional pressure increase switching becomes unnecessary.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an injection compression molding method and apparatus according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a control diagram of an injection molding machine according to the present invention,
2 is a diagram showing the relationship between the tie bar elongation amount and the set mold clamping force in the toggle mold clamping device, FIG. 3 is a diagram showing the relationship between the mold opening amount of the mold and the mold clamping force,
FIG. 4 is an explanatory diagram showing a state of injection compression molding including an injection filling step and a compression step from the start of injection filling to the completion of injection filling of the injection device.

The injection molding apparatus 100 according to the present embodiment
Toggle type mold clamping device 50, injection device 40, and control unit 60
It is composed of

FIG. 1 shows an injection molding apparatus 100 provided with a toggle-type mold clamping device 50. The upper half of the center line shows a state where the toggle mechanism 6 is not fully extended, and the lower half of the center line shows the state where the toggle mechanism 6 is not extended. Indicates a state where it is fully extended. The toggle-type mold clamping device 50 in FIG.
Fixed platen (fixed platen) 2, movable platen (movable platen)
3, a mold 4 (fixed mold 4b and movable mold 4a), a cavity 5, a toggle mechanism 6, a crosshead 7, a mold clamping cylinder (die lock cylinder) 8, a piston rod 9 and a guide rod 10.

In the injection molding apparatus 100 provided with the double toggle type mold clamping device 50, as shown in FIG. 1, three toggle links 6a are provided between the movable platen 3 and the link housing 1.
A pair of upper and lower toggle mechanisms 6b and 6c are provided, and a mold clamping cylinder (die-lock cylinder) 8 is mounted substantially at the center of the outer end surface of the link housing 1, and the tip of the piston rod 9 of the mold clamping cylinder 8 is crossed. A guide rod 10 connected to the head 7 and having the crosshead 7
And the toggle mechanism 6 is operated via the crosshead 7 to move the movable platen (movable platen) 3 with respect to the fixed platen 2 to perform a mold clamping operation. . Reference numeral 11 denotes a tie bar.

Next, the injection device 40 will be described. In this embodiment, the injection device 40 includes a screw 4 in a barrel 41.
2 is provided, and the resin material in the hopper 43 is supplied to the supply zone,
It is configured to be heated and compressed in a compression zone, melt metered in a metering zone, and injected into a nozzle 44 via an injection zone.

A heater for externally heating the resin material is provided on the outer peripheral surface of the barrel 41, and the resin material is sent forward by the rotation of the screw 42.

Reference numeral 46 denotes an injection cylinder, and 47 denotes a forward / reverse rotation motor, which is directly connected to the screw 42 and rotates the screw 42 forward / reverse.

Next, the control section 60 will be described. The control unit 60 includes an injection filling amount setting unit 61 and an injection pressure setting unit 6
2. Injection control unit 63, hydraulic control valve 64, mold clamping force setting means 65, mold clamping control unit 66, hydraulic control valve 67, hydraulic supply source 6.
8a, 68b, injection filling completion detecting section 69, timer 70,
Time setting unit 71, comparison control unit 72, mold clamping force detection unit 73,
Mold clamping cylinder stroke sensor 74 and pressure sensor 7
5 is comprised.

The injection filling amount setting means 61 and the injection pressure setting means 62 are connected to an injection control section 63, and the injection control section 63 controls the operation of a hydraulic control valve 64 for controlling the operation of the injection cylinder 46 and the operation of the forward / reverse rotation motor 47. It is connected to a control device (not shown) for controlling and a mold clamping control unit 66.

The mold clamping control section 66 is connected to a hydraulic control valve 67 for controlling the operation of the mold clamping cylinder 8. Note that 68
a and 68b are simplified hydraulic supply sources.

A pressure sensor 75 or a speed sensor attached to the injection cylinder 46 is connected to an injection filling completion detecting section 69.
Connected to The time setting section 71 and the timer 70 are connected via a comparison control section 72, and the comparison control section 72 is connected to the mold clamping control section 66.

The mold clamping force detecting unit 73 and the mold clamping force setting unit 65 incorporated in the tie bar 11 are connected to the mold clamping control unit 66.

A mold clamping cylinder stroke sensor 74 is provided on the side of the mold clamping cylinder 8 opposite the crosshead 7 on the way of the piston rod 9 and detects the stroke of the mold clamping cylinder 8 when the set clamping pressure is reached. Then, it is used as a means for fixing the operation of the mold clamping cylinder 8 by holding the position.

The operation of the injection compression molding apparatus configured as described above will be described.

First, an injection filling amount setting means is defined as a resin amount obtained by adding a cooling solidification shrinkage amount of a resin calculated in relation to resin properties to a volume of a cavity 5 defined by a fixed mold 4b and a movable mold 4a. 61 and the cavity 5
The injection pressure setting means 62 sets an injection pressure condition having the best injection efficiency from an injection filling pressure range in which the inside can be filled and does not generate burrs, as an injection pressure value.

At the same time, the tie bar elongates by the injection-filling behavior from the set measurement value and injection pressure value, the volume of the cavity 5 and the projected area of the cavity to the mold opening amount corresponding to the amount of cooling, solidification and shrinkage of the resin when the injection-filling is completed. The mold clamping force setting means 65 sets a mold clamping force value that allows the movable mold 4a to be separated from the fixed mold 4b.

In this case, the toggle mechanism 6 is not fully extended, and the relationship between the tie-bar extension amount and the set mold clamping force will be described in detail with reference to FIG.

That is, the principle of generation of the mold clamping force in the toggle-type mold clamping device 50 is as follows: the toggle mechanism 6 is driven to move the movable platen 3 forward, and the movable mold 4a and the fixed mold 4b are touched (at this time, The toggle mechanism 6 is not yet fully extended, K ₀ value), and the movable platen 3 is further pushed toward the fixed platen 2 to extend the tie bar 11 (the mold clamping cylinder 8 is advanced) to generate a mold clamping force. I do. The mold clamping force is the maximum value in the state where the toggle mechanism 6 is fully extended (however, when the die height is adjusted to the mold clamping force value according to the cavity projection area by the mold size to protect the mold, Kma
x value). At this time, the tie bar 11 has the maximum value (△ lma
x value).

When the injection compression molding is performed by utilizing the extension of the tie bar 11, the maximum allowable elongation (△ lmax value) of the tie bar 11 is in a range where the mold opening can be adjusted by the injection filling pressure.

Here, assuming that the mold opening amount corresponding to the amount of resin solidification shrinkage upon injection filling is S value, the maximum mold clamping force K
If the mold clamping force is set to be smaller than the max value, the mold opening amount S can be secured. Even in this state, since the toggle mechanism 6 is in a state very close to the most extended state (linear state), the movable platen 3 does not retreat due to the injection filling pressure.

Further, a state in which the molten resin is almost completely filled at the time of completion of the injection filling (just pack) is defined as an appropriate mold clamping force value. This state will be described in detail with reference to FIG.
FIG. 3 shows the fixed mold 4b when the mold clamping pressure value is changed when the injection filling is performed under the condition that the measured value and the injection pressure value are constant.
4 shows the relationship between the distance of the movable mold 4a and the mold opening amount.

FIG. 3 is a graph of the data obtained from the experiment or from the experiment, and the following findings were obtained from the data. That is, in the case of, 250L
× is intended to obtain a 300 W × 50H × box of 2t (projected area 750 cm ²⁾ as a molded product, such as 5-sided cavity has longitudinal ribs on the sides of the box with a relatively flat, for example, PC case or briefcase The case of molding is shown.

The case 5 shows a case where the surface of the cavity 5 is flat, not a rib structure, and a very flat molded article such as a lens or a disk is formed.
The case (5) shows a case where the cavity 5 has a complicated shape, and a molded product such as an instrument panel or a bumper having a complicated shape, a large shape, and a thick shape as a whole is formed.

As described above, in FIGS.
As the mold clamping pressure is increased from low pressure to high pressure, the mold opening decreases, and tends to move to the left and right with respect to the standard. The inflection points (A, A ′,
A ″) was found to appear.

As a representative example of such experimental results, in the region B where the mold clamping pressure value is smaller than the inflection point A,
Since the movable mold 4a is separated from the fixed mold 4b by the kinetic energy of the resin flow during the injection filling, a large gap is generated between the filled resin and the cavity 5 when the injection filling is completed.

In such a state, the flow rate of the resin becomes discontinuous when shifting from the completion of the injection filling to the compression step,
As a result, defects such as flow marks occur. In order to eliminate the cause of such defective products, a molding method that is extremely difficult to control, such as linking the injection step and the compression step, is required.

Conversely, in a region C where the mold clamping pressure value is larger than the inflection point A, the kinetic energy of the resin flow during the injection filling is reduced without the movable mold 4a relatively moving with respect to the fixed mold 4b. Since the resin can be absorbed, the resin is fully filled (just pack) into the cavity 5 when the injection filling is completed.

In the above-mentioned region C, the resin does not reflow even when moving to the compression step, so that there is no occurrence of defects such as flow marks, and control is performed while the injection step and the compression step are linked. Becomes unnecessary.

Based on the above results, in the present embodiment, the region C was selected. That is, even in the region C, in the region where the mold clamping pressure value is large, the resin pressure in the cavity 5 is increased as a result, and the resin pressure in the cavity 5 is reduced, which is one of the advantages in the injection compression molding. The maximum value (upper limit value) of the mold clamping pressure value is defined from the allowable maximum value of the resin pressure in the cavity 5 which is determined to be appropriate from the shape of the molded product and the physical properties of the resin, and the lower limit value is the inflection point. The range with the mold clamping pressure value corresponding to the point A, that is, the region D was set as an appropriate mold clamping pressure value.

Further, the mold opening behavior accompanying the injection filling is a result given by the extension of the tie bar 11, and although the set mold clamping force is the same as the extension of the tie bar 11, the mold is actually loaded on the mold. Since the mold clamping force showed a tendency to increase, it was found that the relationship between the injection filling pressure, the mold opening amount, and the mold clamping force acted in a direction to automatically balance. That is, in the toggle-type mold clamping device 50, when setting the appropriate mold opening amount, even if the conditions of the appropriate mold clamping force value are set somewhat rough, the direct pressure type is achieved by the automatic balance correction of the mold clamping force due to the extension of the tie bar 11. Compared with the case of the mold clamping device, there is also obtained an advantage that molding control is easy.

In setting the above-mentioned appropriate mold clamping pressure value, the mold opening is defined as shown in FIG. 3, but it is determined whether or not a defect such as a flow mark has occurred by quality inspection of the molded product after molding. Then, the inflection point A can be obtained.

When the initial setting is completed as described above,
Next, the molding operation starts. This will be described with reference to FIG.

(1) Based on the set value of the appropriate clamping force set by the clamping force setting means 65, the clamping control unit 66 controls the operation of the clamping cylinder 8 to reduce the clamping (primary pressure). Do. The detection of the mold clamping force during the mold clamping operation is performed by the mold clamping force detection unit 73 incorporated in the tie bar 11. The advantage is that the tie bar 11 which is the principle of generating the mold clamping force of the toggle mechanism 6 is used.
Since the elongation (stress) behavior is directly measured, the measurement accuracy is the highest. In the case of the conventional method of calculating based on the geometrical relationship of the toggle mechanism 6, there is no disadvantage (accumulation of an operation program close to infinity, the inaccuracy of the operation estimation). Extremely good handling because it is independent of the mold mounting area. And so on.

(2) When the detection signal from the mold clamping force detector 73 matches the set value of the mold clamping force setting means 65, the operation of the mold clamping cylinder 8 is fixed. As means for this, as shown in this embodiment, the stroke of the mold clamping cylinder 8 when the set mold clamping pressure is reached is detected by the mold clamping cylinder stroke sensor 74, and the position of the mold clamping cylinder 8 is maintained so as to keep the position. Controls oil pressure (clamp cylinder position holding control). As another method, the hydraulic pressure of the mold clamping cylinder 8 is controlled so as to maintain the set mold clamping pressure (mold clamping pressure holding control).
The same effect can be obtained by the method.

Note that the above is extremely accurate due to the characteristics of the toggle mechanism (the fluctuation of the movable plate is 1/10 mm or less even if the stroke of the mold clamping cylinder fluctuates by about 1 mm, and therefore has little effect on the mold clamping force). Easy control of mold clamping force.

(3) After the primary mold clamping is completed, the injection filling operation is started.

On the basis of the resin metering value set by the injection filling amount setting means 61 and the injection pressure setting means 62 and the setting value of the injection filling pressure, the injection control section 63 sets a constant filling pressure (one pressure).
Injection filling is performed under pressure control to control the pressure. That is, in the early stage of injection, the flow resistance in the cavity 5 is small, so that high-speed filling is performed. In the late stage of injection, the filling speed is naturally reduced with an increase in the flow resistance in the cavity 5, resulting in a continuous speed gradient. Ideal natural filling flow that does not generate pack pressure
Becomes

Further, during the injection and filling step, the injection control is performed so that the screw 42 does not leave a so-called cushion amount until the screw 42 reaches the forward limit by the pressure control of the injection cylinder 46. By doing so, the detection for confirming the completion of injection filling described later is extremely easy and accurate, and the weighing and injection filling control are also simplified.

Further, even in the cut-off state, the nozzle 44
Since the molten resin is filled in the passage from the inside to the cavity 5 with the set injection pressure, there is no backflow. Injection filling with the cushion amount remaining is also possible. In this case, however, it is necessary to prevent the movable mold 4a from moving after completion of filling the holding pressure set value on the injection side.

(4) The movable die 4a is retracted (opened) in a direction away from the fixed die 4b by the extension of the tie bar 11 in response to the injection filling. When the injection filling is completed, the mold opening amount becomes the maximum, the molten resin is almost completely filled (just pack) in the cavity 5, and the elongation behavior of the tie bar 11 due to the application of the appropriate mold clamping force is like a spring. Since it is acting elastically, there is no need to worry about occurrence of defects such as flow marks even when switching from the injection process to the compression process, so that special switching timing control is not required.

Furthermore, since the elongation behavior of the tie bar 11 acts elastically, even if molding conditions such as resin temperature fluctuate during molding, it acts as a function of absorbing the fluctuation, so that there is no variation in quality. Become.

(5) Next, after the injection filling is completed, a compression step is performed on the mold clamping mechanism side. Here, the detection of whether or not the injection filling is completed is performed by detecting the change of the working oil pressure value in the injection cylinder 46 or the injection piston 48 in the above-mentioned cut-off state.
From the change in the forward movement (injection speed).

That is, since the working oil pressure value in the injection cylinder 46 is controlled to be constant along with the forward movement of the screw 42 so that the injection filling pressure is constant from the start of the injection filling to immediately before the injection is completed, the injection is completed. At this time, that is, when the screw 42 reaches the forward limit, the forward movement of the screw 42 is stopped, and the working oil pressure value in the injection cylinder 46 temporarily increases rapidly. Therefore, by detecting the operating oil pressure value in the injection cylinder 46, the completion of the injection filling can be accurately detected.

However, the present invention is not limited to this, and when the forward movement of the screw 42 or the forward movement of the injection piston 48 is stopped, it may be detected that the injection and filling are completed. Furthermore, it is also possible to use a method for confirming and detecting the completion of injection filling as described above in combination.

(6) When the injection / fill completion detecting section 69 detects the completion of the injection / fill operation, the timer 70 is started to control the compression process. Here, the time at which the mold clamping pressure increase (secondary clamping pressure) start time, the weighing start time, and the holding pressure cooling time are input to the time setting section 71 in advance. The start of metering is set on the basis of the gate sealing time, and in a molding machine incorporating a shut-off valve, the shut-off valve closing operation completion time is set as a reference.

The holding pressure cooling time is calculated as the cooling / solidification time of the resin based on the resin temperature, the mold cooling capacity, the shape of the molded product, and the like, and is set as the holding pressure cooling time (compression completion time). By setting the start of the mold clamping pressurization to be the same as the measurement start time setting, it is possible to prevent the resin from flowing back from the mold cavity 5 to the injection side due to the mold clamping pressurization.

If it is necessary to start the mold clamping pressure increase simultaneously with the completion of the injection filling, the injection cylinder 4
If the pressure setting of 6 is increased according to the set mold clamping force (secondary pressure), the same resin backflow effect can be obtained (the position of the injection cylinder 46 remains at the forward limit).

(7) Here, a slight time lag occurs between the completion of the injection filling and the start of the mold clamping pressure increase. However, since the initially set primary clamping force is continuously applied, the injection filling is performed. The compressive action on the resin due to the elastic recovery force of the elongated tie bar 11 is continued continuously and in response to the cooling, solidification and shrinkage of the resin, and as a result, there is no occurrence of defects due to the time lag. . Further, complicated and advanced timing control of the pressure increase start becomes unnecessary, and the pressure increase start setting can be set very easily. The mold clamping pressure is increased by supplying pressurized oil to the mold clamping cylinder 8 and driving the toggle mechanism 6 again.

(8) The time-out signal of the timer 70 is compared with the set value of the time setting unit 71 by the comparison control unit 72, and when it is found that each set value has been reached, a measurement start signal is output to the injection control unit 63. Then, the mold clamping pressure increase start signal and the compression completion signal are output to the mold clamping control section 66, and after the mold is opened, the product is taken out, and then the next molding operation is started.

(9) The value of the mold clamping force (secondary clamping pressure) after increasing the mold clamping pressure is added for the purpose of improving the transferability of the molded product. In the mold clamping pressure range between the maximum mold clamping pressures, for example, the transferability of the molded article after molding is evaluated and the necessary minimum mold clamping force value is set to the mold clamping force setting means 65.
You can also ask for

It is also possible to make the set values of the secondary mold clamping force and the primary mold clamping force the same. In this case, the compression step is added only by the elastic recovery force of the tie bar 11, In particular, a high effect is expected when the residual distortion of the molded article is reduced to obtain a high-quality molded article with very little deformation.

[0065]

As is apparent from the above description, the operability is extremely high in the present invention because the injection filling step and the compression step need only be a simple control method of controlling the injection pressure and the set clamping force. It will be easier. Furthermore, because of the pressure control, a high-quality molded product can be stably supplied without being affected by fluctuations in molding conditions other than the pressure during molding. In addition, by using injection pressure control that allows injection filling,
The ideal injection filling control that has a continuous speed gradient according to the product shape, does not generate pack pressure, and enables short-time filling can be set very easily and automatically, making control operability extremely easy. is there. Even when the injection filling is completed, the molten resin is in a just-packed state, so that there is no defect such as a flow mark caused by the discontinuity of the resin flow. Since the timing control is not required, the operability of the control can be further simplified. In the mold clamping pressure increase start control in the compression process, from the injection filling process to the compression process switching and the mold clamping pressure increase start,
Since the compression action from the mold clamping side is continuously and fluidly added corresponding to the cooling and solidification of the resin, advanced mold clamping pressure increase timing control is not required, and as a result, the control system is extremely simple, Productivity is greatly improved by reducing the cost of molding machines. Injection filling control is injection pressure control and filling is performed without leaving a cushion amount, so that injection filling completion detection can be detected easily and accurately and mold clamping pressure increase start control can be easily performed. Controls such as the compression step and the start of weighing after completion can be performed by simple control using a timer, and a high-quality molded product can be obtained by an extremely easy operation. Since the mold clamping force is detected directly at the tie bar, which is the principle of the mold clamping force of the toggle-type mold clamping mechanism, the measurement accuracy is extremely high. Because it can be handled, the operability and accuracy of the control are extremely good.

[Brief description of the drawings]

FIG. 1 is a control diagram of an injection molding machine according to the present invention.

FIG. 2 is a diagram illustrating a relationship between a tie bar elongation amount and a set mold clamping force in a toggle-type mold clamping device.

FIG. 3 is a relationship diagram between a mold opening amount of a mold and a mold clamping force.

FIG. 4 is an explanatory diagram showing a state of injection compression molding including an injection filling step and a compression step from the start of injection filling to the completion of injection filling of the injection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Link housing 2 Fixed board 3 Movable board 4 Mold 4a Movable mold 4b Fixed mold 5 Cavity 6 Toggle mechanism 7 Crosshead 8 Mold clamping cylinder 9 Piston rod 10 Guide rod 11 Tiebar 40 Injection device 41 Barrel 42 Screw 43 Hopper 44 Nozzle 46 Injection cylinder 47 Forward / reverse rotation motor 48 Injection piston 50 Toggle mold clamping device 60 Control unit 61 Injection filling amount setting means 62 Injection pressure setting means 63 Injection control unit 64 Hydraulic control valve 65 Mold clamping force setting means 66 Mold clamping control Unit 67 Hydraulic control valve 68a, 68b Hydraulic supply source 69 Injection and filling completion detecting unit 70 Timer 71 Time setting unit 72 Comparison control unit 73 Mold clamping force detecting unit 74 Mold clamping cylinder stroke sensor 75 Pressure sensor

Claims (6)

(57) [Claims] 1. A toggle mechanism for clamping a mold by driving it with a hydraulic mold-clamping cylinder. In the injection filling step, a cooling solidification shrinkage amount of the resin is calculated in advance at the injection mechanism side, and this shrinkage amount is added. The injection pressure is controlled by the injection pressure at which the amount of resin filled in the mold can be filled, and on the mold clamping mechanism side, the resin is filled by the resin pressure filled in the mold cavity in a state where the toggle mechanism is not fully extended. A mold clamping force that allows the mold to open when the tie bar extends to the mold opening equivalent to the amount of cooling, solidification, and shrinkage is applied to the mold in advance, and the toggle mechanism is started at any time after the completion of injection filling is detected. The injection compression molding method characterized in that the mold clamping force is increased in a state in which the mold is fully extended. 2. The injection pressure control according to claim 1, wherein the injection pressure is controlled from a start to a completion of the injection to a constant pressure at which the injection can be performed.
Injection compression molding, characterized in that the filling is carried out by controlling the pressure so that the amount of shrinkage does not remain. 3. A mold clamping force previously applied to the mold according to claim 1 is detected by using a mold clamping force detector incorporated in a tie bar, and a detection signal from the mold clamping force detector is set. An injection compression molding method comprising detecting a stroke of a mold clamping cylinder connected to a toggle mechanism when the mold clamping force is reached, and controlling a hydraulic pressure of the mold clamping cylinder so as to maintain the position. 4. The completion of the injection filling according to claim 1, when the injection driving force of the injection mechanism suddenly starts increasing, and based on a time-out signal of a timer activated by the change of the injection driving force, the mold clamping force is reduced. An injection compression molding method characterized in that pressure increase is started. 5. The completion of the injection filling according to claim 1, wherein the movement of the injection drive unit of the injection mechanism is stopped, and the mold clamping force is increased based on a time-out signal of a timer started from the stop position of the injection drive unit. An injection compression molding method characterized in that pressure is started. 6. An injection control unit comprising an injection filling amount setting means and an injection pressure setting means for performing injection filling based on set values set by the two setting means , and cooling, solidifying and shrinking of the resin by the injection filling. A mold clamping force setting unit that sets a mold clamping force that allows the mold to open by extending the tie bar to a mold opening amount corresponding to the amount, a mold clamping cylinder stroke sensor that detects a stroke of the mold clamping cylinder, In the mold clamping process, the mold clamping force is detected by a mold clamping force detecting unit incorporated in the tie bar, and a set value of the mold clamping force setting unit is compared with a detection signal of the mold clamping force detecting unit to connect a toggle mechanism. When the injection driving force of the injection mechanism starts to rise sharply, or when the movement of the injection driving unit stops, Injection filling completed An injection / fill completion detection unit that generates a signal, a timer that starts based on a detection signal from the injection / fill completion detection unit, a time setting unit that sets a mold clamping pressure increase start time in a compression process, and the time setting unit. An injection compression molding apparatus, comprising: a comparison control unit that compares a set value of the timer with a time-out signal of the timer to generate a pressure increase signal to the mold clamping control unit.