JPH08174615A - Method and apparatus for injection compression molding - Google Patents

Abstract

PURPOSE: To control injection pressure and mold clamping pressure independently of fluctuation in molding conditions by a method wherein pressure which enables filling is controlled during injection filling and the amt. of a resin increased by the amt. of shrinkage of the resin by cooling and solidification is filled, and a mold clamping force which allows the amt. of opening of the mold corresponding to the amt. of shrinkage is used and after injection filling is completed, the mold clamping force is increased. CONSTITUTION: A control part 60 sets the amt. of a resin which includes the vol. of a cavity 28 added with the amt. of shrinkage of the resin by cooling and solidification as a metering value and sets an injection pressure condition wit the most efficient injection within the range of injection filling pressure which enables filling in the cavity 28 and does not generate burrs as an injection pressure value. At the same time, the value of mold clamping force allows that the movable mold 30b may separate from the fixed mold 30a to the amt. of opening of the mold corresponding to the amt. of shrinkage of the resin by cooling and solidification when injection filling is completed, is set from the set metering value and injection pressure value and the vol. of the cavity 28 and the projected area of the cavity. In addition, when completion of injection filling is detected by means of a detecting part 69 for completion of injection filling, a timer 70 is started and the starting time for increasing the mold clamping force is input into a time setting part 71.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection compression molding method in which a closed mold is filled with a molten resin, the mold is slightly opened by the pressure of the filled resin, and then compression is performed on the mold clamping side. And the device.

[0002]

2. Description of the Related Art In the injection compression molding in an injection molding machine, (1) mechanically control the moving and retreating limit of the mold when the mold is opened by the resin pressure injected and filled. (2) Detecting the mold opening amount (the mold opening amount refers to the position of the mold held in the mold opening position that allows for the amount of movement or compression of the mold retracted by the filled resin pressure) Then, the mold clamping pressure or the injection speed is controlled so that the set mold opening amount and mold opening speed are achieved. (3) In the compression process, the mold opening amount of the mold is detected, and the mold clamping speed or mold clamping pressure is changed so as to reach the set mold moving amount and mold moving velocity. Molding and molding of complex shape or thin wall shape.

[0003]

The conventional injection compression molding has the following problems. First, (1) it is difficult to deal with the case where the molding conditions such as the resin temperature change during molding by the method of mechanically limiting the retreat limit of the mold, and therefore the quality of the molded product varies. Since there is a time lag when shifting to the compression process after the completion of filling, the resin flow velocity in the mold becomes discontinuous,
As a result, defects such as flow marks occur. In addition, in order to prevent defects such as flow marks,
An interlocking operation is required to balance the injection mechanism side and the mold clamping mechanism side, and the software and hardware aspects of control become complicated and the operability deteriorates.

(2) In the method of detecting the mold opening amount of the mold and controlling it based on the detection signal, defects such as flow marks caused by the discontinuity of the flow velocity of the resin filled in the mold cavity are eliminated. Although it can be solved a lot, on the contrary, the operability becomes extremely difficult because the software and hardware are considerably complicated.

On the contrary, since the mold opening or compression process can be controlled according to the set value, it is extremely difficult to select the optimum set value, and the flexibility for absorbing the fluctuation of the molding condition during molding is reduced. Therefore, there is a possibility that the non-defective rate will decrease significantly.

Particularly, when it is attempted to control the compression process according to the set value, it is extremely difficult to control the timing for linking the mold clamping side and the injection side, and it is necessary to drive the mold clamping side and the injection side at the same time. As a result, the productivity is significantly reduced due to the unnecessary increase in the size of the molding machine.

The present invention has been made in view of the above problems, and avoids a decrease in productivity due to an unnecessarily large-sized molding machine, and performs molding by simple control of only injection pressure and mold clamping pressure. It is intended to stably supply good products without being affected by the fluctuation of molding conditions.

[0008]

In order to achieve the above object, in the first aspect of the present invention, the cooling solidification shrinkage amount of the resin is calculated in advance on the injection mechanism side during the injection filling process, and the shrinkage amount is calculated. The injection pressure is controlled by an injection pressure capable of filling the amount of resin added to the mold, and on the mold clamping mechanism side, the resin pressure filled in the cavity of the mold corresponds to the amount of cooling and solidification shrinkage of the resin. A mold clamping force that allows the mold to open up to the mold opening amount is applied to the mold in advance, and the mold clamping pressure is increased from an arbitrary point after the completion of injection filling is detected. In the second aspect, the injection filling is performed. The completion is defined as the time when the injection driving force of the injection mechanism starts to rapidly increase, and the mold clamping pressure is started to increase based on the time-out signal of the timer activated by the change of the injection driving force.

Further, in the third aspect of the invention, the completion of the injection filling is defined as the time when the movement of the injection driving force of the injection mechanism is stopped, and the mold clamping pressure is increased based on the time-out signal of the timer started by the stop of the injection driving unit. To start. Further, in a fourth aspect of the present invention, there is provided an injection filling amount setting unit and an injection pressure setting unit, and an injection control unit for performing injection filling based on the two setting units, and a mold corresponding to the cooling solidification shrinkage amount 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 up to the opening amount, and a mold clamping control unit that performs mold clamping based on the mold clamping force setting unit are provided.
When the injection driving force of the injection mechanism starts to rise sharply or when the movement of the injection driving unit stops, the injection filling completion detection unit that generates an injection filling completion signal and the detection signal from the injection filling completion detection unit A timer started based on the above, a time setting unit for setting the mold clamping pressure increasing start time in the compression process, a set value of the time setting unit and a time-out signal of the timer are compared, and the pressure increasing signal is sent to the mold clamping control unit. It is configured to have a comparison control unit for generating.

[0010]

[Function] By controlling the filling pressure during the injection filling process, the resin flow resistance in the cavity of the mold is small at the initial stage of filling, so that high-speed filling is performed, and the resin flow resistance increases at the latter stage of filling, so that the filling speed Is naturally decelerated, so that an ideal natural filling flow (natural flow) that automatically has a continuous velocity gradient during resin filling and that does not generate pack pressure can be obtained.

Further, by filling the amount of resin to which the cooling solidification shrinkage amount of the resin has been added, and by setting the mold clamping force that allows the mold opening amount corresponding to the cooling solidification shrinkage amount, the gold is filled at the time of completion of injection filling. Since the resin is almost completely filled (just packed) in the mold, it is not affected by the occurrence of defects such as flow marks due to the discontinuity of the resin flow velocity in the mold.

Since the proper mold clamping force is applied to the mold even during the injection filling and when the compression process is switched, even if the molding condition changes during molding, the mold clamping force is elastic like a spring. It has the flexibility to work as a physical action.

In the compression step, since the mold clamping pressure is increased after the completion of injection filling is detected, the injection side and the mold clamping side can be prevented from interlocking with each other, so that the molding machine need not be upsized.

Further, even when the mold clamping pressure is increased, the compression action corresponding to the cooling, solidification, and contraction of the resin is continued until just before the pressure increase is switched by the application of the initially set proper mold clamping force. The complicated and sophisticated timing control of pressure increase switching has become unnecessary.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a control conceptual diagram of an embodiment according to the present invention,
2 is a plan view of the mold clamping device, FIG. 3 is a cross-sectional view of the screw engagement adjusting device, FIG. 4 is an explanatory view showing an operating state of the half nut, and FIG.
Is a relationship diagram showing the relationship between the mold opening amount and the mold clamping pressure, FIG.
FIG. 3 is an explanatory view showing a state of injection compression molding including an injection filling process and a compression process from the start of injection filling of the injection device to the completion of injection filling.

The injection compression molding apparatus in this embodiment comprises a mold clamping unit 1, an injection unit 40 and a control unit 60. First, the mold clamping device will be described with reference to FIGS. The mold clamping device 1 shown in FIG. 2 includes a moving cylinder 2, a mold clamping cylinder 3, a tie bar 7, a fixed platen 10, and a screw engagement adjusting device 1.
1, movable plate 20, nut box 21, half nut 2
2, tie bar locking device 26, fixed mold 30a, movable mold 3
0b and the connecting plate 50.

The stationary die 30a is attached to a stationary platen 10 fixed on one end of the machine base 1a, while the stationary platen 10 is mounted on the other end side of the machine base 1a.
A movable mold 30b is attached to the movable plate 20 so as to face the. The facing surfaces of the fixed mold 30a and the movable mold 30b are engaged with each other to form a cavity 28 between the fixed mold 30a and the movable mold 30b. Fixed board 1
The tip ends of the piston rods 6 of the moving cylinders 2, which are fixed to both side surfaces of 0, are attached to the movable platen 20 and can move forward and backward by sliding on the machine base 1a with respect to the fixed platen 10. Reference numeral 4 indicates the internal piston, 4a indicates the piston rod chamber side, and 4b indicates the piston head chamber side.

A plurality of tie bars 7 that penetrate the movable plate 20 are manufactured to have the same overall length (four in the present invention).
One end is fixed to the internal piston 5 of the mold clamping cylinder 3, and the other end is fixed by tightening with a nut or end plate 51 after penetrating the connecting plate 50 in a direction substantially at right angles. The tie bar 7 and the connecting plate 50 prevent the tie bar 7 from rotating by using a key or the like.

An inner piston 5 is provided in the mold clamping cylinder 3 so as to be slidable back and forth, a packing for preventing oil leakage is arranged on the outer periphery of the inner piston 5, and a tie bar 7 is provided on the rod side of the inner piston 5. A ram 53 is fixedly provided on the head side substantially above the center of the internal piston 5 in a convex shape. Further, the ram cylinder 52 engaged with the ram 53 is attached to the ram 53.
Is provided so as to be slidable back and forth, and packing is provided on a sliding portion on the outer periphery of the ram 53 so that oil from the ram chamber 5c does not leak to the piston head chamber side 5b. Reference numeral 5a indicates the piston rod chamber side.

The outer diameter of the ram 53 is, for example, 1/2 or less of the outer diameter of the tie bar 7, or 1/3 of the outer diameter of the internal piston 5.
The length of the ram 53 is set to 1/4 or less so that the tip of the ram 53 contacts the inner part of the ram cylinder 52 before the head end surface side of the internal piston 5 contacts the end surface of the ram cylinder 52 during mold clamping. It has a simple structure.

The movable platen 20 is locked to the tie bar 7 by engaging a half nut 22 described later when the movable mold 30b and the fixed mold 30a come into contact with each other at a substantially middle portion of the tie bar 7. A threaded portion or groove portion 8 is formed for this purpose. One end is fixedly mounted on the movable plate 20 and the other end is screwed into the threaded portion 12 of the adjusting shaft 13 of the screw meshing adjusting device 11 described later, and the half nut 22 is incorporated therein. Here, the screw mesh adjusting device 11 includes a screw portion 12, an adjusting shaft 13, and a pressing member 1.
7, slide key 18, sprocket 19 and presser plate 2
It is composed of 5, etc.

Next, the tie bar locking device 26 will be described with reference to FIG. The tie bar locking device 26 includes a half nut opening / closing cylinder 14, a piston 15, a piston rod 16, a half nut 22, a connecting rod 101, and stoppers 102 and 103.

The half-split nut 22 is provided adjacent to the movable plate 20 and has a set of half-split nuts 22 that are vertically divided into two parts for each tie bar 7. The half-split nut 22a has an opposite meshing side. One end of the piston rod 16 is fixed to the end surface. Further, a piston 15 that engages with the half nut opening / closing cylinder 14 and slides vertically is disposed at the other end of the piston rod 16, and the adjusting plate 10 is provided at the lower end of the half nut opening / closing cylinder 14.
0 is stuck. A connecting rod 101 connected through the half nuts 22a and 22b is arranged on the left and right of the piston rod 16, one end of the connecting rod 101 is fixed to the adjusting plate 100, and the other end is attached to the half nut 22b. It is fixed.

As shown in FIG. 4 (a), the half nut opening / closing cylinder 14 has a piston rod chamber side 15b.
By supplying the pressure oil to the piston 15, the piston 15 is pushed up and the half nut opening / closing cylinder 14 is pushed downward, and the pair of upper and lower half nuts 22a and 22b move while sliding on the nut box 21. The half nut 22 and the tie bar 7 are disengaged from each other, and the stopper 10
It is supposed to stop by abutting on 2, 103.

When it is desired to mesh the half nut 22 with the tie bar 7, pressure oil is supplied to the piston head chamber side 15a of the half nut opening / closing cylinder 14 as shown in FIG. 4 (b). , The piston 15 is pushed down and the half nut opening / closing cylinder 14 is pushed upward, and the half nuts 22a and 22b move while sliding on the nut box 21 and finally come into contact with each other to mesh with the tie bar 7. Is configured to be performed.

Further, the left and right sides of the half nut 22 described above
In the 80-degree direction, one end of the half nut 22 is rotated by a sprocket portion 19 fixed to an end portion of the adjusting shaft 13 which is inserted through the tie bar 7 to rotate the anti-sprocket portion 19.
The end of the adjusting shaft 13 on the side is always in contact with the half nut 22 and slides.

At the other end of the half nut 22, a plurality of insertion chambers for the pressing member 17 are provided in a part of the movable plate 20 on the side opposite to the fixed plate 10 for each half nut 22. The half nut 22 is constantly pressed in the axial direction of the tie bar 7, and when the adjusting shaft 13 is moved to the stationary platen 10 side, the spring of the pressing member 17 is compressed and the counter stationary platen 1 is pressed.
It is arranged to be stretched when moving to the 0 side.

A sprocket portion 19 is provided on the outer peripheral portion of the adjusting shaft 13 in the vicinity of the end on the side opposite to the half nut 22, and a slip key 18 is used to prevent the adjusting shaft 13 from rotating. The sprocket portion 19 is connected by a chain (not shown), and a sprocket that is integrated with an output shaft of a motor (not shown) is connected to the chain, and the chain is driven by the rotation of the motor to move the adjustment shaft 13 back and forth in the axial direction of the tie bar 7. As a result, the position of the half nut 22 can be adjusted so that the half nut 22 that is in contact with the adjusting shaft 13 meshes with the screw portion or the groove portion 8 on the tie bar 7.

As for the outer peripheral portion of the shaft portion of the sprocket portion 19, one end is fixed to the end portion of the nut box 21, and the other end is fixed to the nut box 21 to prevent the sprocket portion 19 from falling off. It is rotatably supported by the holding plate 25. The reference numeral 24 indicates an insertion hole.

The mold clamping device as described above is used in this embodiment for the following reason. The mold clamping mechanism is compact and space can be saved. Since a small amount of pressure oil needs to be supplied to the small-capacity ram chamber 5c, the mold opening and the compression response during injection compression molding are high. By adjusting the hydraulic pressure supplied to a plurality of (four) mold clamping cylinders 3, tilting correction (leveling control) of the movable platen 20 is possible.

Next, the injection device 40 will be described. The injection device 40 in the present embodiment has a screw 4 in a barrel 41.
2 is provided, the resin raw material in the hopper 43 is in the supply zone,
It is configured to be heated and compressed in the compression zone, melt-metered in the metering zone, and injected into the nozzle 44 through the injection zone.

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

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

Next, the control unit 60 will be described. The control unit 60 includes an injection filling amount setting means 61 and an injection pressure setting means 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 detection unit 69, timer 70,
It is composed of a time setting unit 71 and a comparison control unit 72.

The injection filling amount setting means 61 and the injection pressure setting means 62 are connected to the injection control section 63, and the injection control section 63 controls the operation of the hydraulic control valve 64 for controlling the operation of the injection cylinder 46 and the operation of the forward / reverse rotation motor 47. The control device (not shown) for controlling and the mold clamping force setting means 65 are respectively connected.

The mold clamping force setting means 65 is also connected to the mold clamping control unit 66, and the mold clamping control unit 66 is connected to a hydraulic control valve 67 for controlling the operation of the mold clamping cylinder 3. 68
Reference numerals a and 68b denote simplified hydraulic pressure supply sources.

A pressure sensor or a speed sensor (both not shown) attached to the injection cylinder 46 and an injection filling completion detecting section 69 are connected, and the injection filling completion detecting section 6 is connected.
9 is connected to the timer 70. The time setting unit 71 and the timer 70 are connected via the comparison control unit 72, and the comparison control unit 7
2 is connected to the mold clamping control unit 66 and the injection control unit 63, respectively.

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

First, the control unit 60 injects a resin amount obtained by adding a cooling solidification shrinkage amount of the resin calculated according to the physical properties of the resin to the volume of the cavity 28 defined by the fixed mold 30a and the movable mold 30b as a measured value. In addition to the setting by the filling amount setting means 61, the injection pressure setting means 62 sets the injection pressure condition with the best injection efficiency from the injection filling pressure range that can fill the cavity 28 and does not generate burrs.

At the same time, the movable mold 30b is moved to the fixed mold 30a from the set measured value and injection pressure value, the cavity 28 volume and the projected area of the cavity to the mold opening amount corresponding to the cooling solidification shrinkage amount of the resin at the completion of injection filling. The mold clamping force setting means 65 sets a mold clamping force value that allows the mold clamping force to be separated.

In this case, the state where the molten resin is almost fully filled (just pack) at the time of completion of injection filling is set as the proper mold clamping force value. This state will be described in detail with reference to FIG.

FIG. 5 shows the distance between the fixed mold 30a and the movable mold 30b when the mold clamping pressure value is changed when injection filling is performed under the condition that the measured value and the injection pressure value are constant, that is, the mold opening. The relationship with the quantity is shown.

FIG. 5 is a graph of data obtained from the experiment or the experiment, and the following findings were obtained from the data. That is, in the case of, 250 L
A box product of × 300W × 50H × 2t (projected area 750 cm ² ) is obtained as a molded product, and the cavity 28 surface is relatively flat and has vertical ribs on the side surface of the box, such as a personal computer case or a document case. The case of molding is shown.

In the case of (3), the surface of the cavity 28 is flat and does not have a rib structure, but an extremely flat shaped product such as a thin product such as a lens or a disk is formed.

In the case of (2), the surface of the cavity 28 has a complicated shape, and a case where a molded product such as an instrument panel or a bumper having a complicated shape, a large shape or a thick wall shape is formed.

As described above, in FIG.
The mold opening amount decreases as the mold clamping pressure value is increased from low pressure to high pressure, and the mold opening amount tends to move in parallel to the left and right, and in the process of increasing the mold clamping pressure, the rate of decrease of the mold opening amount suddenly increases. Decreasing inflection point (A, A'in FIG. 5,
A ″) appeared.

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 30b is separated from the fixed mold 30a by the kinetic energy of the resin flow during the injection filling, a large gap is generated between the filled resin and the cavity 28 when the injection filling is completed.

In such a state, the flow rate of the resin becomes discontinuous at the time of shifting from the injection filling completion 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 interlocking the injection process and the compression process, is required.

On the contrary, in the 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 does not cause the movable mold 30b to move relative to the fixed mold 30a. Since the resin can be absorbed, the resin was completely filled (just packed) into the cavity 28 at the time of completion of the injection filling.

Further, in the region C described above, since reflow of the resin does not occur even when shifting to the compression process, defects such as flow marks do not occur, and the injection process and the compression process are controlled in conjunction with each other. Is unnecessary.

Based on the above results, the region C was selected in this embodiment. That is, in the region where the mold clamping pressure value is large even in the C region, the resin pressure in the cavity 28 eventually becomes high, and one of the advantages in injection compression molding is that the resin pressure in the cavity 28 is lowered. Therefore, 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 28 which is judged 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. Range with the mold clamping pressure value corresponding to point A of
The region was set to an appropriate mold clamping pressure value.

When setting the above-mentioned appropriate mold clamping pressure value, the mold opening amount was defined as shown in FIG. 5, but it was judged by the quality inspection of the molded product after molding whether there was a defect such as a flow mark. It is also possible to obtain the inflection point A after the above.

When the initial setting is completed as described above,
Next is the molding operation.

When the mold is closed, pressure oil is supplied to the piston rod chamber side 4a of the moving cylinder 2 to move the movable platen 20 and the nut box 21 fixed to the side surface of the movable platen 20.
And the screw mesh adjusting device 11 etc. to the fixed plate 10 side with the tie bar 7
Move along the axis of. First, the screw portion or the groove portion 8 engraved at the substantially middle portion of the tie bar 7 is smoothly inserted into the insertion hole 24 of the movable plate 20 and the movable plate 20 is further moved forward. And fixed mold 30a
The surfaces of the contact cylinders slowly come into contact with each other and are locked, whereby the supply of pressure oil to the piston rod chamber side 4a of the moving cylinder 2 is stopped.

Next, the half nut 22 starts to mesh with the threaded portion or groove portion 8 on the tie bar 7. First, when pressure oil is supplied to the piston head chamber side 15a in the half nut opening / closing cylinder 14 through a pipe (not shown), the half nut 22 advances in a direction substantially perpendicular to the tie bar 7. Here, the die thickness (die height) H of both dies when the movable die 30b and the fixed die 30a are in contact with each other is measured in advance by a scale, and this is measured with a pitch of the screw portion or the groove portion 8 on the tie bar 7. When divided by P (H / P), if there is no fraction below the decimal point due to cutting, then both dies are in light contact with the piston head chamber side 15a of the half nut opening / closing cylinder 14. If pressure oil is supplied, the half nut 22 will move to the tie bar 7
It will completely mesh with the upper screw part or groove part 8.

Contrary to what has been described above, however, when the H / P is not divisible and a fractional part after the decimal point occurs, the pitch (or half of the pitch) of the screw part or groove part 8 on the tie bar 7 is set to the fractional part after the decimal point. The value obtained by multiplying the screw pitch P) of the split nut 22 is the half split nut 22 and the thread portion or groove portion 8 on the tie bar 7.
Is a moving distance A for completely meshing.

That is, after lightly contacting the two molds, the sprocket 19 is rotated by moving the motor connected by the chain by an amount commensurate with the moving distance A to move the adjusting shaft 13 forward and backward. However, the rotation of the motor can be measured in pulses and converted into a moving distance before and after the adjustment shaft 13. In this way, the half nut 22 can be completely meshed with the threaded portion or the groove portion 8 on the tie bar 7.

Further, when the meshing is completed, the mold clamping of the movable mold 30b and the fixed mold 30a by the mold clamping cylinder 3 is ready to start. Thereafter, based on the output signal of the mold clamping control unit 66, the hydraulic control valve 67 is driven to supply pressure oil to the piston rod chamber side 5a of the mold clamping cylinder 3 fixedly mounted on the fixed platen 10, thereby fixing the fixed mold. 30a and movable mold 3
A strong mold clamping between 0b can be started. The mold clamping force applied between the fixed mold 30a and the movable mold 30b is the proper mold clamping pressure value set previously. Further, whether or not the mold clamping is completed can be confirmed by comparing the detected value of the pressure sensor arranged on the piston rod chamber side 5a with the set value.

Next, after the completion of the primary mold clamping, the injection filling operation is started.

The hydraulic control valve 64 is actuated based on the output signal of the injection control unit 63 to operate the piston 4 of the injection cylinder 46.
8 is advanced, and the advance at this time is pressure-controlled based on the injection pressure value set previously.

That is, since the flow resistance in the cavity 28 is small at the early stage of injection, high-speed filling is performed, and in the latter stage of injection, the filling speed is naturally decelerated as the flow resistance in the cavity 28 increases, resulting in a continuous speed. It has an ideal natural filling flow (natural flow) that has a gradient and does not generate pack pressure.

The metering operation for the next shot has already been completed by being performed concurrently with the compression process on the injection device 40 side, and based on the output signal of the injection control unit 63, the forward / reverse rotation motor 47. The molten resin is weighed by the previously set weighing value while driving.

Further, during the injection filling process, the injection control is performed by the pressure control of the injection cylinder 46 so that the screw 42 does not leave a so-called cushion amount until reaching the forward limit.

By doing so, the detection for confirming the completion of injection and filling described later becomes extremely easy and accurate, and the control of measurement and injection and filling becomes simple.

Further, even in the shot-off state, the molten resin is filled in the nozzle 44 and the passage to the cavity 28 with the set injection pressure value, so that the resin does not flow backward.

It is possible to perform injection filling while leaving a cushion amount, but in this case, it is necessary to prevent the movable mold 30b from moving after the filling is completed with the holding pressure setting value on the injection side.

Corresponding to the injection filling, the movable mold 30b is retracted (mold open) in the direction away from the fixed mold 30a. When the injection filling is completed, the mold opening amount becomes maximum, and the molten resin is almost completely filled in the cavity 28 (just pack).
Since it is in a state and the mold clamping pressure value is elastically acting like a spring where elastic force is always added, defects such as flow marks occur even when switching from the injection process to the compression process. Because there is no worry about
No special switching timing control is required.

Further, since the mold clamping acts elastically, even if the molding conditions such as the resin temperature change during molding, it acts as a function of absorbing the fluctuation, so that there is no variation in quality.

Next, after the injection filling is completed, a compression process is performed on the mold clamping mechanism side.

The detection as to whether or not the injection filling is completed can be detected by the change of the operating hydraulic pressure value in the injection cylinder 46 or the change of the forward movement of the piston 48 in the above-mentioned dead state. These states will be described with reference to FIG.

In FIG. 6, the screw 4 is adjusted so that the injection filling pressure is constant from the start of injection filling to immediately before the completion of injection.
The hydraulic pressure value in the injection cylinder 46 is controlled to be constant along with the forward movement operation of 2.

When the injection is completed, that is, when the screw 42 reaches the forward limit, the forward movement of the screw 42 is stopped, so that the hydraulic pressure value in the injection cylinder 46 temporarily and rapidly increases. That is, the completion of injection filling can be accurately detected by detecting the operating hydraulic pressure value in the injection cylinder 46. However, the present invention is not limited to this, and the time when the forward movement of the screw 42 or the forward movement of the piston 48 is stopped may be detected as the completion of injection filling. Furthermore, it is also possible to combine and use the methods for confirming and detecting the completion of injection filling as described above.

In this way, when the injection filling completion detecting section 69 detects the completion of injection filling, the timer 70 is activated to control the compression process.

Here, the mold clamping pressure increase (secondary mold clamping pressure) start time, the measurement start time, and the holding pressure cooling time are input to the time setting section 71 in advance.

The start of measurement is set with reference to the time of gate sealing, and with a molding machine incorporating a shutoff valve, the completion time of shutoff valve closing operation as a reference.

The pressure-holding cooling time is set as the pressure-holding cooling time (compression completion time) by calculating the resin cooling / solidification time based on the resin temperature, the mold cooling capacity and the shape of the molded product.

By starting the mold clamping pressure increase at the same time as the setting of the measurement start time, it is possible to prevent the reverse flow of the resin from the mold cavity 28 to the injection side due to the mold clamping pressure increase.

Here, a slight time lag occurs from the completion of injection filling to the start of mold clamping pressure increase, but since the initially set primary mold clamping pressure is continuously applied, the compression action on the resin is It continues continuously and in response to the cooling and solidification shrinkage of the resin, and as a result, the occurrence of defects due to the time lag is eliminated. Further, complicated and sophisticated timing control for starting pressure increase is not required, and the pressure increase start setting can be set very easily.

When the comparison control unit 72 compares the time-out signal of the timer 70 and the set value of the time setting unit 71 and it is found that each set value has been reached, a weighing start signal is output to the injection control unit 63, and A mold clamping pressure increasing start signal and a compression completion signal are output to the mold clamping control unit 66, the product is continuously taken out after the mold is opened, and then the next molding operation is started.

The mold clamping force (secondary mold clamping pressure) value after the mold clamping pressure increase is added for the purpose of improving the transferability of the molded product. The primary mold clamping pressure and the maximum mold of the molding machine are used. Within the mold clamping pressure range between the clamping pressures, for example, the transferability of the molded product after molding can be evaluated and the required minimum mold clamping force value can be obtained by the mold clamping force setting means 65.

Further, the position of the movable mold 30b in the compression process is detected, and the mold clamping force at the time when the movable mold 30b comes into contact with the fixed mold 30a, that is, at the time of returning to the mold state before injection filling. The value can be set as the secondary mold clamping pressure value.

In the mold clamping device 1 of this embodiment,
Although the mold clamping is performed by the rear mold clamping cylinder 3 that uses the moving cylinder 2 to move the movable platen 20 back and forth, the invention is not limited to this, and the mold clamping cylinder 3 may be provided behind the movable platen 20. Alternatively, an electric mold clamping mechanism may be used. Further, the same effect can be obtained by using the mold clamping device 1 itself as a vertical type instead of the horizontal type as in the embodiment.

[0084]

As is apparent from the above description, in the present invention, the injection filling step and the compression step may be a simple control method of only the pressure control of the injection pressure and the mold clamping pressure, so that the operability is extremely easy. Becomes Further, since the pressure is controlled, it is possible to stably supply a high-quality molded product without being affected by fluctuations in molding conditions other than the pressure during molding. Also, by controlling the injection pressure that enables injection filling,
With an ideal injection and filling control that has a continuous velocity gradient according to the product shape, does not generate pack pressure, and allows short-time filling, it is extremely easy and automatic to control. is there. Even when injection filling is completed, the molten resin is in a just-packed state, so defects such as flow marks due to resin flow discontinuity are completely eliminated, and as a result, extremely high levels are achieved when switching from the injection filling process to the compression process. Since the timing control is unnecessary, the control operability can be further simplified. Even 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 added continuously and fluidly in response to the cooling and solidification of the resin, advanced mold clamping pressure increase timing control is unnecessary, and as a result, the control system becomes extremely simple. Productivity is greatly increased by lowering the cost of the molding machine. The injection filling control is the injection pressure control and the filling is performed without leaving the cushion amount, so that the injection filling completion detection can be detected easily and accurately, and the mold clamping pressure increase start control can be performed easily. The control of the compression process and the start of measurement after completion can be performed by simple control by a timer, and a high quality molded product can be obtained by an extremely easy operation.

[Brief description of drawings]

FIG. 1 is a control conceptual diagram of an embodiment according to the present invention.

FIG. 2 is a plan view of a mold clamping device.

FIG. 3 is a cross-sectional view of a screw mesh adjustment device.

FIG. 4 is an explanatory diagram showing an operating state of a half nut.

FIG. 5 is a relationship diagram showing the relationship between the mold opening amount and the mold clamping pressure.

FIG. 6 is an explanatory diagram showing a state of injection compression molding including an injection filling process and a compression process from the start of injection filling of the injection device to the completion of injection filling.

[Explanation of symbols]

 1 Mold Clamping Device 2 Moving Cylinder 3 Mold Clamping Cylinder 4, 5 Internal Piston 4a, 5a Piston Rod Chamber Side 4b, 5b Piston Head Chamber Side 5c Ram Chamber 7 Tie Bar 8 Screw or Groove 10 Fixed Plate 11 Screw Engagement Adjuster 14 Half Split nut opening / closing cylinder 17 Pressing member 20 Movable plate 22 (22a, 22b) Half split nut 24 Insertion hole 26 Tie bar locking device 28 Cavity 30a Fixed mold 30b Movable mold 40 Injection device 41 Barrel 42 Screw 44 Nozzle 46 Injection cylinder 47 Forward / reverse motor 48 Piston 50 Connecting plate 51 End plate 52 Ram cylinder 53 Ram 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 section 67 Hydraulic control valve 68a, 68b Hydraulic pressure Supply source 69 Injection filling completion detection unit 70 Timer 71 Time setting unit 72 Comparison control unit 100 Adjustment plate 101 Connecting rods 102, 103 Stopper

Claims (4)

[Claims] 1. An injection pressure control is performed at an injection pressure capable of filling a mold with a resin amount obtained by previously calculating a cooling solidification shrinkage amount of the resin on the injection mechanism side during the injection filling step. On the mold clamping mechanism side, a mold clamping force that allows the mold to open up to a mold opening amount corresponding to the cooling solidification shrinkage amount of the resin by the resin pressure filled in the mold cavity is applied to the mold in advance. An injection compression molding method characterized in that the mold clamping pressure is increased from an arbitrary time point after the completion of injection filling is detected. 2. The completion of injection filling according to claim 1 is defined as a time point when the injection driving force of the injection mechanism starts to sharply rise, and the mold clamping pressure is changed based on a time-out signal of a timer activated by a change of the injection driving force. An injection compression molding method, characterized in that pressure increase is started. 3. The completion of the injection filling according to claim 1 is defined as a time point when the movement of the injection driving force of the injection mechanism is stopped, and the mold clamping pressure is increased based on a time-out signal of a timer which is activated when the injection driving unit is stopped. The injection compression molding method is characterized in that 4. An injection control unit comprising injection filling amount setting means and injection pressure setting means, which performs injection filling based on the two setting means, and a mold opening corresponding to the cooling solidification shrinkage amount 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 up to the amount, and a mold clamping control unit that performs mold clamping based on the mold clamping force setting unit,
When the injection driving force of the injection mechanism starts to rise sharply or when the movement of the injection driving unit stops, the injection filling completion detection unit that generates an injection filling completion signal and the detection signal from the injection filling completion detection unit A timer started based on the above, a time setting unit for setting the mold clamping pressure increasing start time in the compression process, a set value of the time setting unit and a time-out signal of the timer are compared, and the pressure increasing signal is sent to the mold clamping control unit. An injection compression molding apparatus having a comparison control unit for generating