JP3293425B2 - Injection low pressure molding method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection low-pressure molding method (injection press molding) in which a molten resin is injected and filled between two molds which are held in an unclosed state in advance, and thereafter compression is performed on the mold clamping side. The present invention relates to an injection low-pressure molding method (injection compression molding) in which a molten resin is injection-filled in a closed mold that has been previously low-pressure mold-closed and then compressed on the mold-clamp side.

[0002]

2. Description of the Related Art In recent years, when resin molded parts used for automobiles, home appliances, building materials and the like are molded by an injection low pressure molding method, they have been molded by various methods as described below. (1) A stopper or the like is provided in the mold clamping mechanism, and the mold is mechanically locked by the stopper at a predetermined mold opening position. Alternatively, the amount of retreat of the mold due to injection filling is regulated by a stopper. The compression step after injection filling is performed by releasing the mechanical lock by the stopper. Alternatively, the compression process is performed by using a separately provided compression-clamping cylinder or the like. In the case of a toggle-type mold clamping mechanism, mold clamping is completed with the toggle mechanism fully extended, and in this state, a predetermined clearance is secured in the mold, and compression is performed with a separately provided mold clamping cylinder or the like. Perform the process. (2) A unit dedicated to compression is mounted between the movable platen and the fixed platen of the mold clamping mechanism, and the unit is provided with a mold opening holding and compression step. (3) By making full use of hydraulic control, the mold is held at a relatively large mold opening position, and the compression process is started by applying a mold clamping force from an arbitrary point during injection filling.

[0003]

However, such a conventional method has the following problems. (1) When shifting from the injection filling step to the compression step, a mechanical lag such as a stopper is temporarily released before performing a time lag. As a result, a flow mark or the like due to discontinuity of the resin flow in the mold is generated. It is difficult to obtain a high quality molded product due to the occurrence of defects. Furthermore, the addition of a mechanical locking mechanism or a mold-clamping cylinder dedicated to compression causes the molding machine to be complicated and large, resulting in a decrease in productivity. (2) Although it is not necessary to modify the molding machine body, the mounting of the unit reduces the effective dimensions of the mold, and causes deformation of the molding machine due to an increase in weight, abnormal wear of sliding parts, and burden on the drive system. Damage to the molding machine such as increase is large.
Further, it requires connection of a control signal for adjusting the timing of the operation of the unit and the operation of the molding machine, and the operability is extremely low. (3) This method is a molding method used to cover the above-mentioned drawbacks of (1) and (2), but it is extremely difficult to set the timing position for starting mold clamping, and therefore the operability is extremely poor. In addition, since the timing of mold clamping start is controlled based on the injection cylinder stroke, there is a variation in the operation of the check ring, the influence of the back pressure setting at the time of measurement, the change in the resin temperature, and the like. It is difficult to stably supply non-defective products because of the state in which the quantity varies. Further, since the injection filling operation and the mold compression operation are performed simultaneously, the specifications of the molding machine need to be increased, and as a result, the productivity is significantly reduced.

[0004]

[Means for Solving the Problems] By solving the problems described above, it is possible to avoid the need for complicated and large-sized molding machines or control systems that are unnecessarily equipped, and to produce high-quality molded products by simple control. In order to stably supply, in the present invention, the first
According to the invention, when performing injection low-pressure molding using an injection molding device that performs clamping by a hydraulic mechanism by driving a mold clamping cylinder, the injection is performed after the toggle mechanism performs mold clamping in a bent state. Initiates the filling operation and detects that the amount of resin being injected during injection filling has reached the amount of resin that has been added to the amount of cooling, solidification, and shrinkage of the resin, based on the amount of change in the detection signal of the clamping force detector incorporated in the tie bar. After that, the injection operation is stopped, and the toggle mechanism is extended to apply a mold clamping force to perform compression. Further, in the second invention, when performing injection low-pressure molding using an injection molding device that performs mold clamping via a toggle mechanism by driving a hydraulic mold clamping cylinder, the mold is clamped in a bent state by the toggle mechanism. After that, the injection filling operation is started, and it is detected based on the amount of change in the control oil pressure value signal of the mold clamping cylinder that the amount of the filled resin during the injection filling has reached the resin amount obtained by adding the amount of cooling, solidification, and shrinkage of the resin. After that, the injection operation is stopped, and the toggle mechanism is extended to apply a mold clamping force to perform compression. In a third aspect of the present invention, in the first and second aspects of the present invention, a molten resin is injected and filled between the two dies which are held in an unclosed state in advance, and then the compression is performed on the mold clamping side. In a molding method, the mold is retracted from a state in which both molds are touched to a mold opening amount corresponding to the amount of cooling, solidification, and shrinkage of the resin, and the mold is moved at a stroke position of a mold clamping cylinder connected to a toggle mechanism. The opening amount is set, and the operating oil pressure of the mold clamping cylinder is controlled so as to maintain the set position during the injection filling operation. further,
In the fourth invention, in the first invention and the second invention,
Inject the molten resin into the mold closed beforehand,
This is an injection low-pressure molding method in which compression is performed on the mold clamping side, and a mold clamping force that allows both closed molds to open by the filled resin pressure is applied to the mold, and then connected to the toggle mechanism. The mold clamping force is set at the stroke position of the mold clamping cylinder thus set, and the operating oil pressure of the mold clamping cylinder is controlled so as to maintain the set position during the injection filling operation. According to a fifth aspect of the present invention, there is provided an injection control unit for controlling an injection filling operation, a mold opening amount setting unit for setting a mold opening position corresponding to a cooling solidification shrinkage amount of the resin, and a tree finger pressure of the filled resin. A mold clamping force setting unit that sets a mold clamping force that allows the mold to be opened by the mold, and a mold clamping control unit that controls the mold clamping operation based on a set value set by a preselected molding method. In addition, an injection filling monitor for monitoring the amount of filling resin during injection filling based on a change amount of a detection signal of a clamping force detection unit incorporated in the tie bar or a control hydraulic signal of the clamping cylinder, and an injection filling monitoring unit. A timing control unit for transmitting an injection stop signal to the injection control unit and a mold start signal to the mold control unit based on the detection signal.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention provides a high-quality molded product by performing a high-precision mold opening control or a mold clamping force control with an extremely simple control system with almost no modification of a molding machine. Stable supply at low cost. In the present invention, in an injection low-pressure molding method in which a molten resin is filled in a mold held in an unclosed state in advance and then compressed on the mold clamping side, the mold opening corresponding to the amount of resin solidified by shrinkage upon cooling is reduced. The injection filling is performed while holding the mold at the quantity position. In addition, in the injection low-pressure molding method in which the molten resin is filled in a previously closed mold and then compressed on the mold clamping side, a mold clamping force that allows the mold to be opened by the filled resin pressure is used. Injection filling is performed under the loaded condition. After detecting that the filled resin amount has reached the resin amount obtained by adding the cooling solidification shrinkage amount of the resin, the injection filling is stopped and the compression process is performed by applying a mold clamping force, so that the resin is added to the mold. Is almost fully filled (just pack), so that even when the compression process is switched, there is no occurrence of defects such as flow marks due to the discontinuity of the resin flow velocity in the mold.
Therefore, it is not necessary to perform an extremely sophisticated timing control for switching the compression process, which is conventionally required. Further, based on the amount of change in the detection signal of the mold clamping force detector incorporated in the tie bar, or on the basis of the amount of change in the control oil pressure value signal of the mold clamping cylinder, the injection filling amount during injection filling is detected. As a result, the injection-filling amount is controlled on the mold clamping side, and errors in the filling amount caused by the injection side such as fluctuations in measured values and fluctuations in the operation of the check ring can be eliminated. And a high-quality molded product having a very small particle size can be stably obtained.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 8 relate to an embodiment of the present invention,
1 is an overall configuration diagram of an injection molding apparatus, FIG. 2 is a flowchart showing a procedure for setting initial conditions of mold clamping, FIG. 3 is a flowchart showing a procedure for molding operation, and FIG. 5 is a flowchart illustrating a procedure for setting initial conditions of mold clamping according to another embodiment, FIG. 6 is a flowchart illustrating a procedure of a molding operation according to another embodiment, and FIG. 7 is a method for detecting the amount of injection-filled resin according to another embodiment. FIG. 8 is a graph for explaining the relationship between the mold clamping force and the tie bar elongation.

As shown in FIG. 1, an injection low-pressure molding apparatus 100 according to the present invention comprises a mold clamping device 20, an injection device 40, and a control device 60. The mold clamping device 20 includes a fixed platen 2, a movable platen 3, an end platen 1, a mold clamping cylinder 8, a tie bar 11, a toggle mechanism 6, a crosshead 7, a piston rod 9, a guide rod 10, a fixed mold 4b, and a movable mold 4a. And so on. The stationary mold 4b is attached to a stationary platen 2 fixed to the upper surface of one end of a machine base (not shown), while the movable die facing the stationary plate 2 is mounted on the upper surface of the other end of the machine base. 4 a is attached to the movable platen 3. The opposing surfaces of the fixed mold 4b and the movable mold 4a are configured to engage with irregularities, and the fixed mold 4b
A cavity 5 is defined between the movable mold 4a and the movable mold 4a. The movable platen 3 can slide on the machine base with respect to the fixed platen 2 to move forward and backward.

The tie bar 11 penetrating the movable platen 3
A plurality of pieces having the same overall length (4 in the present invention)
And one end thereof is fixed to the fixed platen 2,
The other end is fixed to the end platen 1 after penetrating the movable platen 3. The upper side of the center line indicates the low pressure mold clamping state before injection filling, and the lower side indicates the high pressure mold clamping state at the time of completion of the compression step.

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.

[0010] A heater for externally heating the resin material is provided on the outer peripheral surface of the barrel 41, and the resin material is fed 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 so as to rotate the screw 42 forward / reverse.

Next, the control device 60 will be described. As shown in FIG. 1, the control device 60 includes an injection control unit 61, a timer 62, a timing control unit 63, and an injection filling monitor unit 6.
4. Mold clamping force setting unit 65, mold clamping force detecting unit 66, mold clamping control unit 71, mold clamping cylinder stroke sensor 72, mold opening amount setting unit 73, mold opening amount sensor 74, and hydraulic control valves 68 and 6.
9. It is composed of hydraulic pressure sources 70a, 70b and the like.

The injection control unit 61 is connected to the injection cylinder 46 via a hydraulic control valve 69, and is also connected to a timing control unit 63. The timing control unit 63 is connected to the injection control unit 61 and the timer 62, is connected to the injection filling monitor unit 64, and is also connected to the mold clamping control unit 71.

On the other hand, the mold clamping force setting section 65
Is connected to the mold clamping force detecting unit 66 which is also connected to the injection filling monitor unit, and is also connected to the mold opening amount setting unit 73 and the mold clamping control unit 71. Mold opening amount setting section 7
3 is connected to a mold opening sensor incorporated in the movable platen 3. The mold clamping control unit 71 includes a mold clamping cylinder stroke sensor 7.
2 and connected to transmit a control command to a hydraulic control valve 68 that controls the operating hydraulic pressure of the mold clamping cylinder 8.

Main features of the above devices are as follows. The mold clamping force detector 66 directly measures the extension state (stress change behavior) of the tie bar, which is the principle of the mold clamping force of the toggle mechanism 6. As a result, high response and high accuracy of mold clamping force detection can be realized. The mold opening amount sensor 74 is used when setting the mold opening amount. In this case, since the mold clamping force is in a no-load state, there is no deformation of members such as the movable platen. Accurate detection of the mold opening amount is possible, and handling is not hindered at the time of molding operation, and operability is improved. Specifically, an encoder, a linear scale, or the like is employed. The mold clamping cylinder stroke sensor 72 can also employ an encoder, a linear scale, or the like, and in that case, may be attached to the crosshead 7.

The operation of the injection low-pressure molding apparatus 100 configured as described above will be described. FIG. 2 shows one embodiment of a procedure for setting initial conditions of mold clamping. Injection low-pressure injection is performed in which molten resin is injected and filled into both molds which are held in an unclosed state in advance, and then compression is performed on the mold clamping side. In the case of molding (injection press molding), initial conditions are set according to the following procedure. (1) The maximum clamping force in the clamping compression step is set in advance by adjusting the die height. (2) The hydraulic control valve 68 is operated by the mold clamping control unit 71 to move the movable mold 4a forward to the fixed mold 4b. Tie bar 1
When the mold clamping force detecting unit 66 incorporated in the unit 1 detects that both molds have touched, the forward movement of the movable mold 4a is stopped, and the mold connected to the toggle mechanism 6 by the mold clamping cylinder stroke sensor 72. The clamping cylinder stroke is detected, and the mold clamping controller 71 sets the origin as the mold touch point (S ₀ ). (3) After setting the mold touch point, the movable mold 4a is moved backward. The mold closing cylinder stroke when the detection signal of the mold opening amount sensor 74 reaches the mold opening amount setting value (S) corresponding to the amount of cooling, solidification and shrinkage of the resin set in the mold opening amount setting unit 73 in advance is set. It is detected by the cylinder stroke sensor 72 and stored in the mold opening setting section 73 as a mold opening setting value (S ₁ ). (4) After the initial conditions are set, the mold clamping operation during injection filling in injection press molding is controlled based on the set die opening amount set value (S ₁ ).

After the initial conditions have been set as described above, the injection press molding operation is performed according to the procedure shown in FIGS. (1) destination clamping control unit 71 based on the mold opening amount setting value set in the mold opening amount setting unit 73 (S ₁₎ performs the mold clamping by controlling the hydraulic pressure control valve 68. After the detection signal of the mold clamping cylinder stroke sensor 72 reaches the set value (S ₁ ), the injection filling operation is started (the toggle mechanism 6 is in the refracted state),
During injection filling, the hydraulic pressure of the mold clamping cylinder 8 is controlled so as to maintain the set value (S ₁ ) (position holding control). here,
Due to the clamping force boosting characteristic of the toggle mechanism 6, even if, for example, the stroke of the clamping cylinder fluctuates by 1 mm, the movable platen 3
(Ie, the mold clamping cylinder stroke is 1
/ 10 mm or less can be easily controlled), and extremely high precision and high reproducibility of mold opening control can be realized. (2) After the start of the injection filling, the injection filling monitor 64 monitors the amount of the injection filling resin. There are two methods for detecting the amount of the injection-filled resin by adding the amount of cooling, solidification, and shrinkage of the resin in the injection press molding, and there are two methods, which will be described in detail with reference to FIG. The case where the detection is performed using the detection signal of the mold clamping force detection unit 66 is as follows. That is, since the mold is held in an open state at a mold opening position corresponding to the amount of cooling, solidification, and shrinkage of the resin in advance, until the resin is fully filled in the mold,
Since no load is applied to the tie bar 11, little change appears in the detection signal. When the resin is fully charged, the position of the toggle mechanism 6 is controlled by the mold opening set value (S ₁ ), that is, since the toggle mechanism 6 is in the mechanical lock state, the movable mold 4a is filled with the resin. All of the pushing force (mold opening force) is applied to the tie bar 11, and as a result, the detection signal rises sharply. Therefore, the point at which the detection signal starts to rise sharply is set as the comparison set value (K ₁ ) by the injection and filling monitor 64 to monitor the amount of the injection and filling resin. The case where the control is performed using the control oil pressure value signal of the mold clamping cylinder 8 is as follows. That is, the control oil pressure value of the mold clamping cylinder 8 is increased in proportion to the increase of the resin pressure in the mold cavity 5 due to the injection filling, and the mold opening amount setting value (S ₁ )
Is held. Therefore, the resin pressure calculated from the injection filling conditions (injection pressure and injection speed) and the projected area of the mold cavity 5, or the resin pressure corresponding to the injection filling amount during non-defective molding, the mold clamping cylinder 8
Is set as the comparison set value (K ₂ ) by the injection and filling monitor 64 to monitor the amount of the injected and filled resin.
As a detection signal of the mold clamping force detection unit 66, either the mold clamping force or the amount of extension of the tie bar 11 may be used. Further, as the control oil pressure value signal of the mold clamping cylinder 8, a supply oil pressure value to the mold clamping cylinder, a control signal value of a hydraulic control valve, an oil pressure value in the mold clamping cylinder, and the like can be adopted.

Since the injection filling amount is controlled on the basis of the detection signal on the mold clamping side as described above, an error factor of the filling amount caused by the injection side such as a fluctuation in the measured value and the check ring operation can be eliminated. The variation in weight of the molded product is extremely small, and high quality can be achieved. (3) When detecting that the detection signal of the injection filling monitor section 64 has reached the comparison set value (K ₁ or K ₂ ) (comparison set value reaching point E), the timing control section 63 injects into the injection control section 61. A compression start process is performed by transmitting a stop signal and a mold clamping start signal to the mold clamping control unit 71 to extend the toggle mechanism 6. By doing so, since the mold is almost fully filled with resin (just pack), there is no occurrence of defects such as flow marks due to the discontinuity of the resin flow rate in the mold even when the compression process is switched. is there. Therefore, it is not necessary to perform an extremely sophisticated timing control for switching the compression process, which is conventionally required.

(4) Injection control section 6 based on injection stop signal
The following two methods can be adopted for the injection stop operation in step 1. Stop and hold the forward movement of the injection cylinder (holding pressure switching operation). The resin filling passage is shut off (shut-off valve closing operation). (5) Control of the injection side and the mold clamping side after the start of the compression process
The detection is performed based on the time-out signal set values (t ₁ , t ₂ ) of the timer 62 which is started at the same time when the timing control unit 63 detects that the comparison set value reaching point (E) has been reached. Here, the weighing start time t ₁ is based on the gate sealing time, and when the shut-off valve is incorporated, it is the shut-off valve closing operation completion time, and the weighing operation is performed after the lapse of the weighing start time t _1. Prepare for the next molding. The cooling completion time t ₂ is calculated by calculating the resin cooling time based on the resin temperature, the mold cooling capacity, the shape of the molded product, and the like, and is set as the compression completion time. After the cooling completion time t ₂ elapses, the product is removed through the mold opening operation. Do.

Next, in the case of an injection low-pressure molding method (injection compression molding) in which a molten resin is injected and filled into a mold which has been closed in advance, and then compression is performed on the mold clamping side, the initial stage of mold clamping is performed according to the procedure shown in FIG. Set the conditions. (1) The maximum clamping force in the clamping compression step is set in advance by adjusting the die height. (2) The hydraulic control valve 68 is operated by the mold clamping control unit 71 to move the movable mold 4a forward to the fixed mold 4b. Tie bar 1
When the mold clamping force detecting unit 66 incorporated in the unit 1 detects that both molds have touched, the forward movement of the movable mold 4a is stopped, and the mold connected to the toggle mechanism 6 by the mold clamping cylinder stroke sensor 72. The clamping cylinder stroke is detected, and the mold clamping controller 71 sets the origin as the mold touch point (S ₀ ). (3) After setting the mold touch points, the movable mold 4a is fixed to the fixed mold 4
Push forward to b side. When the detection signal of the mold clamping force detection unit 66 reaches the mold clamping force set value (P) that allows the mold to be opened by the filled resin pressure set in the mold clamping force setting unit 65 in advance, the mold clamping is performed. The cylinder stroke is detected by the mold clamping cylinder stroke sensor 72 and is stored in the mold clamping force setting section 65 as the mold clamping force set value (S ₃ ). (4) At the same time, from the viewpoint of mold protection at the time of mold clamping operation, the mold protection speed range for regulating the mold clamping speed near the mold touch point to an extremely low speed is determined by the retreat amount of the mold clamping cylinder stroke from the mold touch point ( S ₂ ) is set by the mold clamping force setting section 65. Although the setting of the mold protection speed range (S ₂ ) can be omitted, it is desirable to set the range as far as possible from the viewpoint of safety. (5) After setting the initial conditions, based on the set mold clamping force set value (S ₃ ) and the set mold protection speed range set value (S ₂ ),
The mold clamping operation during injection filling in injection compression molding is controlled.

As described above, the setting of the initial condition is completed.
After that, the injection compression molding is performed according to the procedure as shown in FIGS.
Perform the shape operation. (1) Mold protection speed range previously set by mold clamping force setting unit 65
Set value (S_Two), Based on the high-speed type forward operation → low-speed type
Control the forward movement. Here, the molding cycle was shortened.
High-speed forward movement is also required for
High-speed and low-speed switching control is required. (2) After switching from high speed to low speed, set in the mold clamping force setting section 65 first.
Set mold clamping force set value (S _Three) Based on mold clamping force control
Reference numeral 71 controls the hydraulic control valve 68 to perform mold clamping. Mold clamp
The detection signal of the cylinder stroke sensor 72 is the set value
(S_Three) Is reached (the toggle mechanism 6 is in the refracted state), and then ejected.
At the start of the filling operation, the set value (S
_Three) Is controlled so that the hydraulic pressure of the mold clamping cylinder 8 is maintained.
(Position holding control). Here, as in the case of the first embodiment
In addition, due to the clamping force boosting characteristics of the toggle mechanism 6, extremely high precision
Mold control with high accuracy and reproducibility.
High-speed → low-speed switching control accuracy has been improved to ensure stable mold clamping.
Shortening of molding cycle by expanding control and high-speed range
Can be achieved. (3) After the injection filling is started, the injection filling monitor 64
Monitor the amount of filled resin. Resin in injection compression molding
Of Injection Filling Resin by Adding Cooling Solidification Shrinkage
There are two methods, which will be described in detail with reference to FIG. The detection signal of the mold clamping force detector 66 (also in the first embodiment)
In the same manner as above, the mold clamping force or the amount of elongation of the tie bar 11 is used.
Can be performed using:
You. That is, the mold is opened by the pressure of the filled resin.
Mold clamping force that allows for
The mold opening behavior, the toggle mechanism 6 sets the mold clamping force set value (S
_Three) Is in the mechanical lock state because the position
Therefore, the mold opening behavior in this case is such that the tie bar 11 is extended.
Caused by being lengthened. That is, injection filling = mold
Opening behavior = detection signal
The change in the number is noticeable.

Here, injection filling = mold opening behavior = tie bar 11
FIG. 8 shows the correlation of the elongation. That is, generation principle of the clamping force of the toggle mechanism 6, the tie bar 11 by pressing the further movable mold 4a from the mold touch point (T) in the stationary mold 4b is extended to △ l ₀ → △ lmax,
As a result, a mold clamping force (Pmax) is generated. That is,
The tie bar 11 elongation (△ lmax) is in a range where the mold opening behavior due to injection filling can be exhibited. Here, the amount of elongation of the tie bar 11 when the initial mold clamping force (P) is applied is Δl ₁
Then, the extension of the tie bar 11 when adding the mold opening (S) corresponding to the amount of cooling, solidification and shrinkage of the resin is Δl ₂ , and the mold clamping force at this time indicates P ₂ . Therefore, based on the cooling solidification shrinkage amount calculated from the mold cavity volume and the resin physical properties (temperature, type, etc.), the comparative set value (K ₃ , P ₂ if the mold clamping force is set, and the tie bar 11 elongation amount is set. If there is, (△ l ₂ ) is set in the injection and filling monitor section 64 to monitor the amount of the injection and filling resin. A control oil pressure value signal of the mold clamping cylinder 8 (in this case, similarly to the first embodiment, a hydraulic pressure value supplied to the mold clamping cylinder, a control signal value of the hydraulic control valve, a hydraulic value in the mold clamping cylinder, etc. can be adopted). The following is a case where the method is used. That is, the control pressure value of the mold clamping cylinder 8 is increased in proportion to the increase of the resin pressure in the mold cavity 5 due to the injection filling, and the position holding control of the mold clamping force set value (S ₃ ) is performed. . Therefore, injection filling conditions (injection pressure, injection speed)
And the control pressure value of the mold clamping cylinder 8 corresponding to the resin pressure calculated from the projected area of the mold cavity 5 or the resin pressure corresponding to the injection filling amount at the time of molding a non-defective product as a comparison set value (K ₄ ). The amount of the injection-filled resin is set and monitored by the injection-fill monitor 64. As described above, even in the injection compression molding, since the injection filling amount is controlled based on the detection signal reference of the mold clamping side, an error factor of the filling amount due to the injection side such as a fluctuation of a measured value and a check ring operation can be eliminated. Therefore, variation in weight of the molded product is extremely small, and high quality can be obtained. (4) The detection signal of the injection filling monitor 64 has reached the comparison set value (K ₃ or K ₄ ) (the point at which the comparison set value is reached,
E), the timing control unit 63 transmits an injection stop signal to the injection control unit 61 and a mold clamping start signal to the mold clamping control unit 71 to extend the toggle mechanism 6 and perform a compression step. , The timer 62 is started. By doing so, the resin is almost fully filled (just pack) in the injection molding even in the injection compression molding. There are no defects. Therefore, it is not necessary to perform an extremely sophisticated timing control for switching the compression process, which is conventionally required. (5) The injection stop operation and the control of the injection side and the mold clamping side after the start of the compression process are performed in the same manner as in the first embodiment.

[0023]

As described above, in the present invention, the following excellent effects can be exhibited. (1) At the same time when the amount of the injected filling resin during the injection filling reaches the resin amount value obtained by adding the amount of cooling, solidification, and shrinkage of the resin, the injection filling is stopped, and the molding is performed by applying the mold clamping force to perform compression. Since the resin in the mold is in a just-pack state, there is no occurrence of defects such as flow marks due to the discontinuity of the resin flow.As a result, extremely advanced timing control at the time of switching the compression process is not required, and operability is improved. Keep it simple. (2) Since the injection filling amount is controlled on the mold clamping side, it is possible to eliminate a filling amount error factor due to the injection side such as measurement value and check ring operation fluctuation, thereby stably producing a high quality molded product. Can supply.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an injection molding apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a procedure for setting initial conditions of mold clamping according to the embodiment of the present invention.

FIG. 3 is a flowchart showing a molding operation procedure according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a method for detecting an injection filling resin amount according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a procedure for setting initial conditions of mold clamping according to another embodiment of the present invention.

FIG. 6 is a flowchart showing a molding operation procedure according to another embodiment of the present invention.

FIG. 7 is an explanatory view showing a method for detecting an injection filling resin amount according to another embodiment of the present invention.

FIG. 8 is a graph illustrating the relationship between mold clamping force and tie bar elongation according to another embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 end platen 2 fixed platen 3 movable platen 4a movable die 4b fixed die 5 cavity 6 toggle mechanism 7 crosshead 8 mold clamping cylinder 9 piston rod 10 guide rod 20 mold clamping device 40 injection device 60 control device 61 injection control unit 62 Timer 63 Timing control unit 64 Injection filling monitoring unit 65 Mold clamping force setting unit 66 Mold clamping force detection unit 68, 69 Hydraulic control valve 70a, 70b Hydraulic power source 71 Mold clamping control unit 72 Mold cylinder stroke sensor 73 Mold opening amount setting unit 74-inch opening degree sensor 100 injection low pressure molding apparatus K ₁ compares the set value K ₂ compares the set value K ₃ compares the set value K ₄ compares the set value E Comparative setpoint destination point S type opening amount set values S ₁ type opening amount set value S type ₂ protection speed range set value S ₃ type clamping force setting value t ₁ measurement start time t ₂ the cooling completion time

Claims (5)

(57) [Claims] When performing injection low-pressure molding using an injection molding apparatus that performs mold clamping via a toggle mechanism by driving a hydraulic mold clamping cylinder, after the toggle mechanism performs mold clamping in a bent state, The injection filling operation is started, and based on the amount of change in the detection signal of the mold clamping force detection unit incorporated in the tie bar, the fact that the amount of resin filled during injection filling has reached the resin amount obtained by adding the amount of cooling, solidification, and shrinkage of the resin An injection low-pressure molding method comprising: stopping the injection operation after the detection; and extending the toggle mechanism to apply a mold clamping force to perform compression. 2. When performing injection low-pressure molding using an injection molding apparatus that performs mold clamping via a toggle mechanism by driving a hydraulic mold clamping cylinder, after the mold is clamped in a bent state by the toggle mechanism. Injection operation is started after the injection filling operation is started, and it is detected that the filling resin amount during the injection filling has reached the resin amount obtained by adding the cooling solidification shrinkage amount of the resin based on the change amount of the control oil pressure value signal of the mold clamping cylinder. An injection low-pressure molding method, wherein the operation is stopped and the toggle mechanism is extended to apply a mold clamping force to perform compression. 3. An injection low-pressure molding method in which a molten resin is injected and filled between two molds previously held in an unclosed state, and thereafter, compression is performed on a mold clamping side. After the mold is retracted to the mold opening position corresponding to the cooling solidification shrinkage amount, the mold opening amount is set at the stroke position of the mold clamping cylinder connected to the toggle mechanism, and the set position is set during the injection filling operation. 3. The injection low-pressure molding method according to claim 1, wherein the operating hydraulic pressure of the mold clamping cylinder is controlled so as to maintain the pressure. 4. An injection low-pressure molding method in which a molten resin is injected and filled in a mold which has been closed in advance, and then compression is performed on the mold clamping side, wherein both molds closed by the pressure of the filled resin are opened. After applying a mold clamping force to the mold, the mold clamping force is set at the stroke position of the mold clamping cylinder connected to the toggle mechanism, and the set position is maintained during the injection filling operation. 3. The injection low-pressure molding method according to claim 1, wherein the hydraulic pressure of the mold clamping cylinder is controlled. 5. An injection control unit for controlling an injection filling operation, a die opening amount setting unit for setting a die opening position corresponding to an amount of cooling, solidification and shrinkage of a resin, and a die by a tree finger pressure of the filled resin. A mold clamping force setting unit that sets a mold clamping force that allows the mold to open, and a mold clamping control unit that controls the mold clamping operation based on a set value set by a preselected molding method. An injection filling monitor for monitoring the amount of resin being filled during injection filling based on a detection signal of a mold clamping force detection unit incorporated in the sensor or a change amount of a control hydraulic signal of the mold clamping cylinder; and a detection signal of the injection filling monitor. An injection low-pressure molding apparatus comprising: a timing control unit for transmitting an injection stop signal to the injection control unit and a mold start signal to the mold control unit based on the injection control signal.