JP3371661B2 - 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 compression is performed on the mold clamping side after completion of the filling. ) Or injection molding of molten resin in a mold which has been previously closed by low-pressure mold clamping and then compressed on the mold clamping side (referred to as injection compression molding).

[0002]

2. Description of the Related Art In recent years, resin molded parts used for automobiles, home appliances, building materials, etc. have improved surface transferability as exterior materials, have high added value such as laminating skin materials for decoration, and have reduced thickness. The contradictory properties of cost reduction, such as material cost saving and weight saving, are also required. As a molding method satisfying these requirements, an injection low-pressure molding method has attracted attention and trials for practical use have been studied. In the conventional injection low-pressure molding, the following method has been used. (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 mold retreat due to injection filling is regulated by a stopper. The compression process after injection filling is performed by releasing the mechanical lock by the stopper. Alternatively, the compression process is performed using a separately provided mold clamping cylinder for compression. In the case of a toggle type mold clamping mechanism, mold clamping is completed when the toggle mechanism is fully extended, and in this condition a predetermined gap is secured in the mold and compression is performed with a mold clamping cylinder etc. attached separately. Carry out the process. (2) A unit dedicated to compression is mounted between the movable platen and the stationary platen of the mold clamping mechanism, and the mold opening amount holding and the compression process are carried out by the mounted unit.

However, such a conventional method has the following problems. (1) When shifting from the injection filling process to the compression process, a mechanical lag such as a stopper is temporarily released before a time lag occurs. As a result, a flow mark due to discontinuity of resin flow in the mold, etc. It is difficult to obtain a high-quality molded product due to the defects. Further, a mechanical lock mechanism or a die-clamping cylinder dedicated to compression is added to the molding machine, which complicates and increases the size of the molding machine. As a result, productivity is reduced. (2) Although the main body of the molding machine does not need to be modified, the mounting of the unit causes a reduction in the effective size of the mold, deformation of the molding machine due to an increase in weight, abnormal wear of sliding parts, and a load on the drive system. Increased damage to the molding machine is large.
Further, it requires connection of control signals for matching the timing of the operation of the unit and the operation of the molding machine, and the operability is extremely low.

Therefore, as a method for covering the above drawbacks, the following method is being adopted. That is, the mold is held at a relatively large mold opening position by making full use of hydraulic control, or a mold clamping pressure that allows the mold to open relatively large by the filled resin pressure is applied. By controlling the timing of starting the mold clamping based on the injection cylinder stroke from an arbitrary point during injection filling, the injection filling process and the compression process by the mold clamping side are operated simultaneously, and the mold clamping pressure during the compression process is multi-staged. To control.

[0005]

However, such a conventional method still has the following problems. Timing control of multistage switching such as mold clamping start and mold clamping pressure during compression process is performed on the basis of injection cylinder stroke, that is, variations in check ring operation, influence of back pressure setting during measurement, and resin temperature Since the control error factor is generated due to the variation of the filling resin amount due to the variation on the injection side, the control accuracy varies, and as a result, it is difficult to stably supply a good product.

The mold clamping operation of multistage switching such as the mold clamping start and the mold clamping pressure during the compression process is carried out by detecting an arbitrary reference point of the injection cylinder stroke which is a timing signal. This means a response delay when detecting an arbitrary reference point of the injection cylinder stroke, a signal response delay for starting operation to the mold clamping side after detection, and the mold clamping side starts operation after receiving a signal. In this case, for example, many control response delays such as response delay due to compressibility of hydraulic oil and hydraulic pressure loss when the mold clamping side is a hydraulic cylinder system are included.

Since the actual injection filling operation is extremely fast, that is, a short time, it is considered that the injection filling operation and the compression operation on the mold clamping side are completely different from the set conditions due to the control response delay. To be In other words, it is a method considered to eliminate quality defects such as flow marks and respond to higher quality and higher added value, but in reality, setting the molding conditions is made more complicated, Due to the delay in control response, it is difficult to maintain a stable supply of non-defective products.

[0008]

In order to solve the above problems, the present invention reduces unnecessary response delay of the control system,
Avoid complicated and large-sized molding machines and control systems, and stably supply high-quality molded products with simple control.

[0009] In the first aspect of the present invention, hydraulic
By the toggle mechanism driven by the mold clamping cylinder
Using an injection low-pressure molding device that performs mold clamping, injects and fills molten resin between both molds that are held in an unclosed state in advance,
After that, in the injection low-pressure molding method in which compression is performed on the mold clamping side, after the mold is retracted to a predetermined mold opening position from the state where both molds are touching while the toggle mechanism is in a bent state, the toggle mechanism is Set the mold clamping position at the stroke position of the connected mold clamping cylinders and set the stroke of the mold clamping cylinder in advance during the mold clamping operation after the start of molding operation.
When the first mold clamping state is detected, the first timer is started at the same time, and the working hydraulic pressure of the mold clamping cylinder is controlled so as to maintain the set value .
Injection filling operation based on multiple timeout signals
To set the mold clamping position and mold clamping pressure in one or more steps.
The mold clamping is controlled in stages, and the injection pressure or injection during the injection filling operation is controlled.
Detects that either one of the exit speeds has reached the set value
The second timer is activated at the same time
The mold clamping pressure and injection pressure based on
We decided to control it gradually .

According to the second aspect of the present invention, a hydraulic mold clamping cylinder is provided.
Injection low to perform mold clamping by a more driven toggle mechanism
This is an injection low-pressure molding method in which molten resin is injected and filled into a mold that has been closed in advance using a pressure molding device , and then compression is performed on the mold clamping side. After applying a mold clamping pressure that allows both molds closed by the mold to be opened, the mold clamping force is set at the stroke position of the mold clamping cylinder connected to the toggle mechanism, and the molding operation operation is performed. During the mold clamping operation after the start, the stroke of the mold clamping cylinder has the preset initial mold
Upon detecting that the clamped state has been reached, the first timer is started at the same time, and the operating hydraulic pressure of the mold clamping cylinder is controlled so as to maintain the set value, and a plurality of the first timers are operated .
Based on the time-out signal of
Therefore, the mold clamping position and mold clamping pressure can be clamped in one step or multiple steps.
Controls the injection pressure or speed during the injection filling operation.
If either one of them reaches the set value, it is detected.
For multiple timeout signals of the second timer which is activated at times
Based on this, mold clamping pressure and injection pressure are controlled in one or multiple stages
I decided to do it.

In the third invention, in the first invention or the second invention, the detection of the injection pressure or the injection speed during the injection filling operation reaches the advance limit of the injection cylinder stroke and the advance limit. When the injection filling control is performed based on the preset setting value of the injection speed of one step or multiple steps, the stroke position of the injection cylinder The detection signal within the range is the injection pressure, and when performing injection filling control based on the preset value of the injection pressure that can fill the mold cavity set in advance, the detection signal within the stroke position range is The injection speed was used.

Further, in the fourth invention, the first invention or
In the second invention, when the molds are closed, both molds are
The cylinder clamping position
The origin of the mold clamping cylinder
The mold clamping position and the mold clamping force are set based on the trocar position, the mold clamping operation is controlled based on the set value during the molding operation, and the hydraulic pressure of the mold clamping cylinder is maintained so as to maintain the set value. To control.

In the fifth invention, the mold clamping position setting section for setting the mold clamping position in multiple stages, the mold clamping pressure setting section for setting the mold clamping pressure in multiple stages, and the mold clamping position for detecting the mold clamping position. A sensor, a mold clamping pressure sensor that detects the mold clamping pressure, a mold clamping cylinder stroke sensor that detects the mold clamping cylinder stroke, a first timer that starts when the initial mold clamping state is reached, and an injection filling operation A second timer that starts at the same time as the injection pressure or the injection speed reaches a set value, the set value of the mold clamping position setting section, the set value of the mold clamping pressure setting section, the detection signal of the mold clamping position sensor, and the mold. A mold clamping control section that controls a mold clamping operation based on a detection signal of a clamping pressure sensor, a detection signal of a mold clamping cylinder stroke sensor, and a plurality of timeout signals of the first timer and the second timer, and injection filling It has an injection control unit that controls the operation, and also an injection pressure detection unit and an injection speed detection unit that detect the injection pressure and the injection speed during the injection filling operation, and a position setting that sets the detection range of the injection pressure and the injection speed. And a comparison control unit for activating the second timer based on the detection signals of the injection pressure detection unit and the injection speed detection unit and transmitting a pressure control start signal to the injection control unit. did.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, highly accurate mold clamping position and mold clamping pressure are controlled in multiple stages by interlocking with injection filling operation with an extremely simple control system, which requires almost no modification of a molding machine. To provide a stable supply of high quality molded products at low cost. That is, according to the present invention, the first start-up that is started at the same time when the preset initial mold clamping state is reached.
The injection and filling operation is started based on a plurality of time-out signals of the timer, and the mold clamping position and the mold clamping pressure are controlled in one stage or multiple stages to perform simultaneous injection and mold clamping operations.

In this case, the detection of the initial mold clamping state is, in the injection press molding, the mold clamping cylinder stroke position connected to the toggle mechanism when the mold is opened to a predetermined mold opening position, and the injection compression is performed. In molding, it is the stroke position of the mold clamping cylinder connected to the toggle mechanism when the mold clamping pressure that allows the mold to open due to the filled resin pressure is applied. The second which is activated at the same time when it detects that the injection pressure or the injection speed during the injection filling operation has reached the set value.
Based on a plurality of time-out signals of the timer, the mold clamping pressure and the injection pressure are controlled in one stage or multiple stages to perform the compression process.

As described above, the simultaneous operation of injection and mold clamping and the one-step or multi-step control of the mold clamping position and the mold clamping pressure are performed on the basis of the signal on the mold clamping side. Since the control error factor caused by the variation of the filling resin amount due to the mismatch and the injection side can be eliminated, a high quality molded product can be stably obtained.

Furthermore, when the injection pressure or the injection speed during the injection filling operation reaches the set value, that is, the injection filling behavior changes to the filling behavior in which the molten resin is almost completely filled (just packed) into the mold cavity. When the mold clamping pressure and the injection pressure are controlled synchronously based on a plurality of time-out signals of the second timer which is activated at the time, the molten resin in the mold cavity (in this case, the resin is solidifying while it is solidifying). In a certain condition, excessive pressure load can be avoided, the backflow of resin from the mold cavity to the injection side can be prevented, and the molten resin is replenished at the same time as the resin cools and solidifies and shrinks. Therefore, it is possible to obtain a very high quality molded product free from external defects such as deformation, warpage and shrinkage and internal residual stress.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 5 relate to an embodiment of the present invention,
FIG. 1 is an overall configuration diagram of an injection low-pressure molding apparatus, FIG. 2 is a flowchart showing a mold clamping initial condition setting procedure, FIG. 3 is a flowchart showing an injection press molding operation procedure, and FIG. 4 is a step explaining a compression process start timing setting procedure. FIG. 5 is a flow chart showing an injection compression molding operation procedure.

As shown in FIG. 1, the injection low-pressure molding apparatus 100 of 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. Etc. The fixed mold 4b is attached to a fixed platen 2 fixed to the upper surface of one end of a machine base (not shown), while the movable mold is opposed to the fixed platen 2 on the upper surface of the other end of the machine base. 4 a is attached to the movable platen 3. The opposed surfaces of the fixed mold 4a and the movable mold 4b are configured to engage with the unevenness, and the fixed mold 4b is formed.
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 and can move back and forth.

The tie bar 11 penetrating the movable plate 3 is
A plurality of products having the same diameter over the entire length (4 in the present invention)
Individual pieces), one end of which is fixed to the fixed plate 2,
The other end is fixed to the end platen 1 after penetrating the movable platen 3.

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 device 60 will be described. The control device 60, as shown in FIG.
Timer 62, second timer 63, comparison control unit 64, position setting unit 65, injection pressure detection unit 66, injection speed detection unit 67,
Mold clamping control unit 70, mold clamping pressure setting unit 71, mold clamping pressure sensor 72, mold clamping position setting unit 73, mold clamping position sensor 74, mold clamping cylinder stroke sensor 75, and hydraulic control valve 67.
a, a hydraulic control valve 67b, a hydraulic pressure source 68a, a hydraulic pressure source 68b, and the like.

The injection control unit 61 is connected to the injection cylinder 46 via a hydraulic control valve 67a, and is also connected to a first timer 62 and a second timer 63. Comparison control unit 6
4 is connected to the position setting unit 65 and the second timer 63, and is also connected to the injection pressure detection unit 66 and the injection speed detection unit 67.

On the other hand, the mold clamping control unit 70 uses the first timer 62.
Is connected to the second timer 63, is connected to the mold clamping pressure sensor 72 connected to the end of the tie bar 11 penetrating the fixed platen 2 via the mold clamping pressure setting unit 71, and is connected to the movable platen 3. The mold clamping position sensor 74 and the mold clamping setting unit 73 are connected, and the mold clamping cylinder stroke sensor 75 is connected.
Is also connected so as to send a control command to a hydraulic control valve 67b that controls the operating hydraulic pressure of the mold clamping cylinder 8.

The main features of the above-mentioned devices are as follows: (1) The mold clamping pressure sensor 72 is the principle of generating the mold clamping pressure of the toggle mechanism, that is, the extended state of the tie bar (stress change behavior).
Since it is measured directly, it is possible to realize highly responsive and highly accurate mold clamping pressure detection. (2) The mold clamping position sensor 74 is used at the time of mold clamping position setting (mold opening amount setting) in the case of injection press molding. In this case, the mold clamping pressure is in an unloaded state, so Since there is no change in the device members, it is possible to detect the mold clamping position with high accuracy as in the case of direct measurement with a mold. In addition, the molding operation does not hinder the handling at all, and it is not necessary to attach and detach the sensor each time the mold is replaced, so the operability is extremely good. Encoders, linear scales, etc. are used. (3) The mold clamping cylinder stroke sensor 75 uses an encoder and a linear scale. The mounting location may be the crosshead portion.

The operation of the injection low-pressure molding apparatus 100 configured as above will be described. FIG. 2 shows one embodiment of a procedure for setting mold clamping initial conditions when performing injection press molding or injection compression molding. Initial conditions are set by the following procedure.

(1) By adjusting the die height in advance,
The maximum mold clamping pressure (Pmax) during the mold clamping compression process is set. (2) While monitoring the mold clamping pressure (P) with the mold clamping pressure sensor 72, move the movable mold 4 from the mold clamping completed state (Pmax state).
a is retracted (in this case, the mold clamping pressure is reduced). When the mold clamping pressure P = 0, the mold clamping position sensor 74 detects the mold clamping position (movable plate position = movable mold position) and sets the origin (S ₀ ).
The mold clamping cylinder stroke sensor 75 detects the mold clamping cylinder stroke position connected to the toggle mechanism 6 and sets the origin (S _s ). The above setting operation shows the case where the maximum mold clamping pressure (Pmax) setting completed state is the mold clamping completed state. In other cases, for example, the movable mold 4a is moved from the mold open state to the fixed mold side. The mold clamping position and the mold clamping cylinder stroke position may be set to the origin by detecting the touch of both molds by the mold clamping pressure sensor 72 by moving the mold forward.

(3) After setting the origin, the movable mold 4a is moved backward. At this time, the mold clamping position sensor 74 is used to move the movable mold 4a.
The amount of backward movement (mold opening amount) of is detected and compared with each position setting value set in advance by the mold clamping position setting unit 73,
The mold clamping position is set at the mold clamping cylinder stroke position connected to the toggle mechanism 6 (in this case, the mold clamping initial setting in injection press molding is shown). In the present embodiment, for example, a mold clamping position setting operation is performed when the core material is molded for the purpose of high added value and cost reduction, and at the same time, the skin material is laminated in the mold (skin integrated molding). Show as.

Here, the mold clamping position (S
₁), After injection of the core material after setting the skin material
Mold clamping position (S₂, But S₁> S₂) Is set
Of the mold clamping position sensor 74 during the backward movement of the movable mold 4a.
The detection signal (S) shows that each set value (S₁, S₂) Reached
When (S = S₂, S = S₁) Mold clamping cylinder stroke
The position is detected by the mold clamping cylinder stroke sensor 75,
Mold clamping position set value (S₂= SS₂, S₁= SS₁)age
Then, it is stored in the mold clamping position setting unit 73. Therefore, the type
Multi-stage tightening position (S₁, S₂, S₃...)
Stroke position of mold clamping cylinder by the same procedure as above
(S₁= SS₁, S₂= SS₂, S₃= SS ₃...)
Should be set.

(4) After setting the mold clamping position, the movable mold 4a is again used.
To move the mold forward, and apply mold clamping pressure after the mold touch point.
Load on. That is, here, injection compression molding
Allow the mold to open due to the filled resin pressure at
Clamping pressure (P₁) And injection pressure
During injection filling process in shrink molding or injection press molding
And the mold clamping pressure (P₂, P₃...)
To set. Clamping pressure sensor during forward movement of the movable mold 4a
The detection signal (P) of the rotor 72 is preset in the mold clamping pressure setting section 7
Each set value (P₁, P₂, P₃...)
When it reaches (P = P₁, P = P₂, P = P₃···)of
Set the mold clamping cylinder stroke position to the mold clamping cylinder stroke.
The mold clamping pressure set value (P₁= P
P ₁, P₂= PP₂, P₃= PP₃...) as the mold
It is stored in the tightening pressure setting unit 71.

Due to the characteristics of the toggle mechanism 6, the link portions (6a, 6b, 6) of the toggle are increased as the mold clamping pressure is increased.
When c) shifts from the bent state to the linear state, an uncontrollable region of the mold clamping pressure occurs in a range in the immediate vicinity of the linear state. Therefore, such an uncontrollable region (size of the molding device, toggle mechanism 6 It is desirable to avoid setting the mold clamping pressure within a mold clamping pressure range of approximately several% before the maximum mold clamping pressure Pmax is generated, though it depends on the combination shape of the link portions. In fact, since it is in a very small range, it has been confirmed that there is no problem when performing injection press molding or injection compression molding.

(5) After setting the mold clamping initial conditions, set mold clamping position set values (SS ₁ , SS ₂ ...) And mold clamping pressure set values (PP ₁ , PP ₂ , PP ₃ ...) On the basis of,
The mold clamping operation of injection press molding or injection compression molding is controlled based on the stroke position of the mold clamping cylinder connected to the toggle mechanism 6. By doing so, due to the mold clamping pressure boosting characteristic of the toggle mechanism 6, even if the mold clamping cylinder stroke position varies by 1 mm, for example, the position fluctuation of the movable platen 3 (directly to the mold clamping stop position or the mold clamping pressure value). Since it is 1/10 mm or less (actually, the mold clamping cylinder stroke position can be easily controlled with an accuracy of 1/10 mm or less), it is extremely accurate and highly reproducible. Mold clamping pressure control can be realized.

Next, the injection press molding operation procedure will be described with reference to FIG. In the present embodiment, there is a case in which, for example, the integral skin-bonding molding is performed using injection press molding in which the mold clamping stop control can be performed at an arbitrary position with the mold opened.
As an example. (1) Based on the mold clamping position set value previously set by the mold clamping position setting unit 73 (SS ₁ , in this case, the mold opening position for setting the skin material in the mold) is shown. 70 controls the hydraulic control valve 67b to perform mold clamping. When the detection signal (S _s ) of the mold clamping cylinder stroke sensor 75 reaches the set value (S _s = SS ₁ ), the mold clamping cylinder 8 is hydraulically controlled so as to hold the set value (SS ₁ ) to perform the mold clamping. It is stopped and held (the toggle mechanism 6 controls the position holding in the bent state).

(2) The skin material is set in the mold. Here, if the skin material is in the form of a sheet (in this case, it is used in the case of a relatively flat product), the injection low-pressure molding apparatus 10
0 is inserted between the movable mold 4a and the fixed mold 4b by using a skin material conveying device or the like attached separately. Further, in the case of a deep-shaped product having relatively large irregularities, the skin material is generally formed in a shape similar to the product shape. In this case, after fitting and setting in the movable mold 4a, , Fix by vacuum suction. As the skin material, a non-woven fabric type, a laminated skin type, a film type or the like is appropriately selected according to the required characteristics such as decoration or texture (softness) to be added.

(3) After setting the skin material, the mold clamping position set value (SS ₂ , where S
Based on (S ₁ > SS ₂ > die touch point), the mold clamping control unit 70 controls the hydraulic pressure control valve 67b to perform mold clamping. When the detection signal (S _s ) of the mold clamping cylinder stroke sensor 75 reaches the set value (S _s = SS ₂ ), the hydraulic pressure of the mold clamping cylinder 8 is controlled so that the set value (SS ₂ ) is maintained (the toggle mechanism 6). Position control is performed in the bent state), and the first timer 62 is activated to control the injection filling operation and the mold clamping operation. The first timer 62 may be activated at the time when the mold clamping position set value (SS ₁ ) is reached. in this way,
The first timer 62 can be activated when an arbitrary mold clamping position set value is reached other than in the case of the skin-integrated laminating molding, and the timing signal of the activation is also based on the mold clamping cylinder stroke position reference. Therefore, control with high accuracy and high reproducibility can be realized. The first timer 62 is preset with the injection filling start timing time (T ₁ ) and the switching start timing time (T ₂ , T ₃ ...) Of the mold clamping position or the mold clamping pressure. In this embodiment, the switching start timing time is the timing time (T ₂ = P) at the time of multistage control of the mold clamping pressure during the injection filling operation.
P ₂ , T ₃ = PP ₃ ...).

(4) Timeout of the first timer 62 (T
₁), The injection control unit 61 starts the injection filling operation.
It Similarly, the timeout (T₂, T
₃...) based on the mold clamping pressure setting unit 71 in advance.
Clamping pressure set value set in (PP₂, PP₃···)of
Mold clamping pressure control is performed at the same time as the injection filling operation. for example
For example, the time-out signal (T₂) Is detected
After that, the mold clamping control unit 70 controls the hydraulic control valve 67b.
And clamp the mold. Mold clamping cylinder stroke sensor 75
Detection signal (S_s) Reaches the set value (S_s= PP
₂), Set value (PP₂) To hold the mold clamping cylinder
8 to control the hydraulic pressure and
Issue (T₃Position control (toggle mechanism 6)
Is in a refraction state). Similarly, the timer of the first timer 62
Im out (T₃) Is detected, the mold clamping cylinder strike
Make sure that the detection signal of the roque sensor 75 and the set value match.
(S_s= PP₃) Control mold clamping. After that, the above operation control
By repeating the above, multistage control of the mold clamping pressure is performed. According to
And, of course, the injection filling motion
Multiple stages of mold clamping position during operation or multiple stages of mold clamping position and mold clamping pressure
Even in the case of combination, for example, timing time
(T₂= SS₃, T₃= SS_Four...) or (T₂
= SS ₃, T₃= PP₂...) can be controlled by setting
It becomes Noh.

As described above, on the basis of the detection signal on the mold clamping side, that is, on the basis of the mold clamping cylinder stroke position signal, the start timing control of the injection filling operation and the mold clamping position and the mold clamping pressure on the mold clamping side are set to 1. By performing the step or multi-step switching start timing control at the same time, synergistically with the highly accurate and reproducible control effect of the timing control signal detection described above, the injection side and the mold clamping side due to the control response delay are combined. Since there is no operation mismatch, and the control error factor caused by the variation in the amount of filled resin due to the injection side can be completely eliminated, extremely accurate simultaneous operation control of injection and mold clamping can be performed.

Furthermore, since the detection accuracy of the timing control signal is extremely high, the control system can use the time-out signal of the simplest timer for the operation control of injection and mold clamping, and as a result, extremely high quality molding is possible. It is possible to obtain the product at low cost. In addition, by applying injection press molding, which performs injection filling in the pre-opened state, to the skin-integrated laminating molding, damage to the skin material during injection filling is avoided as much as possible, while maintaining the texture, decoration, etc., of the core material. Molding becomes possible. As a matter of course, the time-out signal of the first timer 62 is set to 0 (T ₁ =
When set to 0), injection filling is performed immediately after the completion of the initial mold clamping, and the molding cycle is shortened. Also, T ₁ = T ₂
If set to, the injection and mold clamping will start simultaneously, and the molding cycle can be further shortened. In addition, the resin flow inside the mold cavity due to injection filling and the mold by moving the mold clamping position on the mold clamping side. Since continuity is obtained in the resin flow state in the cavity, the effect of preventing flow mark defects and the like can also be obtained.

(5) When it is detected that the injection pressure or the injection speed during the injection filling operation detected by the injection pressure detection unit 66 or the injection speed detection unit 67 has reached each set value set in advance by the comparison control unit 64. While switching from the injection filling operation to the injection pressure holding operation, the second timer 63 is activated to control the injection pressure and the mold clamping pressure in the compression process on the mold clamping side. Here, a procedure for setting each set value will be described with reference to FIG.

FIG. 4 shows the procedure for setting the compression process start timing. (A) A preset injection filling amount (resin amount obtained by adding the resin cooling and solidification shrinkage amount) and injection speed (one stage or multiple stages). When performing injection filling based on the set value of (injection speed) (injection speed control filling), the following procedure is performed.

The range in which the timing signal for starting the compression process is detected is the forward limit of the injection cylinder stroke (point E).
Then, the position setting unit 65 sets the injection cylinder stroke position in the region near the completion of injection filling as the position setting value (monitoring start point, M) until reaching the forward limit (point E).
By doing so, the mutual relationship between the filling behavior on the injection mechanism side and the filling behavior in the mold cavity 5 can be detected most accurately, and the cooling and solidification behavior of the resin in the mold cavity 5 in the subsequent compression process. It is possible to realize multistage pressure control of the mold clamping pressure and the injection pressure corresponding to. At the same time, the comparison control unit 64 sets the compression process start timing signal as a comparison set value (K value) according to the injection pressure on the injection mechanism side. By setting the timing signal with the injection pressure, it is possible to comprehensively understand the filling behavior of the resin in the mold cavity 5 from the injection mechanism side. Therefore, there are variations in the filling amount due to fluctuations in the measured value, check ring operation, and during molding. It is possible to stably and accurately detect the timing signal without being affected by the disturbance factors such as the fluctuation of the resin temperature.

Next, the above-mentioned set values (M point, K value)
The start of the compression process is controlled based on the above. When the injection cylinder stroke reaches the monitoring start point (M), the injection pressure detector 66 starts monitoring the injection pressure. The injection pressure needs to be increased in order to maintain the injection speed set according to the filling behavior in the mold cavity 5, and when the detection signal of the injection pressure detection unit 66 reaches the K value (the set pressure arrival point, P) The injection filling operation is switched from the injection speed control to the injection pressure control (injection filling operation → injection pressure holding operation), the second timer 63 is started, and the multistage control of the mold clamping pressure is performed based on the timeout signal of the second timer 63. (Compression process),
Performs multi-step control of injection pressure (injection pressure maintaining process).

(B) When injection filling is performed based on preset values of injection filling amount (resin amount obtained by adding resin cooling and solidification shrinkage amount) and injection pressure (fillable pressure value) (injection pressure control) The filling procedure is as follows. With this filling method, high-speed filling can be performed at the initial stage of filling, and the filling speed is naturally reduced as the filling progresses, and an ideal filling control method (natural flow) that suppresses the pack pressure that causes burr formation can be obtained. . The setting of the range (M) for detecting the timing signal for starting the compression process and the timing signal (in this case, the injection speed (K ′)) is the same as in (a) above. Based on the set values (points M and K '), the mold clamping start is controlled. When the injection cylinder stroke reaches the monitoring start point (point M), the injection speed detector 67 starts monitoring the injection speed. By injection filling by controlling the injection pressure capable of filling, the injection speed is naturally reduced corresponding to the filling behavior in the mold cavity. When the detection signal of the injection speed detection unit 67 reaches the K'value (set speed arrival point, V), the injection filling operation is switched to the injection pressure holding operation, the second timer 63 is activated, and the second timer 63 times out. Multistage control of the mold clamping pressure (compression process) and multistage control of the injection pressure (injection pressure maintaining process) are performed based on the signal.

(6) By thus controlling the operation of mold clamping and injection based on the two-stage detection signal reference of the time-out signal reference of the first timer 62 and the time-out signal reference of the second timer 63, that is, injection filling. By performing the mold clamping control during the behavior and the synchronous control of the mold clamping and the injection during the injection filling behavior, the molten resin in the mold cavity is cooled and solidified in the compression process. In consideration of this, pressure control of injection and mold clamping is performed.
Therefore, it is possible to prevent an excessive pressure load on the resin (molded product) in the mold cavity, and to reverse the resin from the mold cavity to the injection side (deformation due to weight variation of the molded product and residual stress remaining, (Which causes warpage) can be prevented, and further, the molten resin can be replenished from both the mold clamping side and the injection side according to the cooling solidification shrinkage of the resin. As a result, it is possible to obtain a high-quality molded product that is free from external defects such as deformation, warpage, and shrinkage and internal residual stress, and has extremely small weight variation. Furthermore, in the case of integral skin-bonding molding, high-quality core material is formed, adhesion between the core material and the skin material is improved, and even bonding of the skin material is performed during the compression process by pressure control. Will be done.

(7) In the second timer 63, the timing time (t ₂ ) corresponding to the injection pressure multi-stage (p ₂ , p ₃ ...) Set in the injection control unit 61 in advance in the injection pressure holding process is set. , T ₃ ...) And the measurement start time (t _E ) are set. Further, in the mold clamping compression step, the mold clamping pressure multistage (P
The timing time (T ₂ ′, T ₃ ′ ...) And the mold clamping completion time (T _E ) corresponding to P ₂ ′, PP ₃ ′ ...) are set. Here, the metering start time (t _E ) is set on the basis of the time of the gate seal, and when the shutoff valve or the like is incorporated, is set on the basis of the completion time of the shutoff valve closing operation. The mold clamping completion time (t _E ) is set by calculating the resin cooling time from the resin temperature, the mold cooling capacity, the shape of the molded product, and the like.

(8) Based on the time-out signals (t ₂ , t ₃ ...) Of the second timer 63, the injection control section 61 causes the injection pressure in the injection pressure-holding step (holding pressure, p ₂ , p ₃ ...・) Is controlled in multiple stages, and the metering operation is started based on the time-out signal (t _E ) to prepare for the next molding. Similarly, the timeout signal (T ₂ ′, T _2
3 ', ...) on the basis of, for example, time-out signal (T _2' after detecting), mold clamping control unit 70 controls the hydraulic pressure control valve 67b, to start the compression process. When the detection signal (S _S ) of the mold clamping cylinder stroke sensor 75 reaches the set value (S _S = PP ₂ ′), the hydraulic pressure of the mold clamping cylinder 8 is controlled so as to maintain the set value (PP ₂ ′). Then, the position holding control is continued until the time-out signal (T ₃ ′) of the second timer 63 is detected. After that, the above operation control is repeated to perform multistage control of the mold clamping pressure in the compression process, and the mold clamping control unit 70 controls the hydraulic control valve 67b based on the time-out signal (t _E ) to perform the mold opening operation. After that, the product is taken out to complete a series of molding operations. In this way, by accurately detecting the change from the injection filling behavior to the injection filling behavior and controlling the timing position of control start of the compression process with high accuracy, the operation control of injection and mold clamping in the compression process is controlled. The system can use the simplest timer timeout signal, and as a result, extremely high quality molded products can be obtained at low cost.

Next, the injection compression molding operation procedure will be described with reference to FIG.
The order will be described. The injection compression molding operation follows the procedure below.
Therefore, it is carried out. (1) The filled tree previously set by the mold clamping pressure setting unit 71
Mold clamping pressure setting value that allows the mold to open due to oil pressure
(PP₁), The mold clamping control unit 70 controls the hydraulic control valve 6
7b is controlled to perform mold clamping. Mold clamping cylinder stroke
Detection signal of sensor 75 (S_S) Reaches the set value (S
_S= PP₁), Set value (PP₁) Hold the mold
Controls the hydraulic pressure of the cylinder 8 (the toggle mechanism 6 is set in the bent state).
(Holding control) and activate the first timer 62.
Control the injection filling operation and the mold clamping operation. In addition, the first
At the time of injection filling start timing,
Between (T₁) And the mold clamping pressure multi-stage (P
P₂, PP₃When switching start timing corresponding to
Between (T₂, T ₃...) is set.

(2) Based on the time-out signal (T ₁ ) of the first timer 62, the injection control section 61 starts the injection filling operation. Similarly, based on the time-out signals (T ₂ , T ₃ ...) Of the first timer 62, for example, after detecting the time-out signal (T ₂ ), the mold clamping control unit 70 controls the hydraulic control valve 67 _b. And clamp the mold. When the detection signal (S _S ) of the mold clamping cylinder stroke sensor 75 reaches the set value (S _S = PP ₂ ), the hydraulic pressure of the mold clamping cylinder 8 is controlled so as to maintain the set value (PP ₂ ). The position hold control is continued until the time-out signal (T ₃ ) of the first timer 62 is detected after refraction. After that, the above operation control is repeated to perform multistage control of the mold clamping pressure. Thus, the control response is achieved by simultaneously performing the injection timing operation start timing control and the one-stage or multi-stage pressure switching timing control of the mold clamping pressure based on the mold clamping side signal (the mold clamping cylinder stroke position signal reference). Since there is no inconsistency between the operation on the injection side and the mold clamping side due to delay, and the control error factor caused by the variation in the amount of filled resin due to the injection side can be completely eliminated, extremely accurate injection and mold clamping are possible. The operation control of is realized. Further, as described above, since the mold clamping cylinder stroke position signal can be detected with extremely high precision, the injection system and the mold clamping operation control can use the time-out signal of the timer, which is the simplest in the control system. As a result, high quality molded products can be obtained at low cost. As in the case of injection press molding, the time-out signal (T ₁ = 0) of the first timer 62,
Alternatively, it is possible to set T ₁ = T _2, and it is possible to obtain a high-quality molded product by further shortening the molding cycle and continuity of the resin flow state in the mold capacity.

(3) Mold opening behavior according to injection filling behavior
You The mold opening behavior in this case is mainly that the tie bar 11 extends.
(Toggle mechanism 6 includes first timer 6)
2 timeout signal (T₂~ T₃Position)
The mechanical lock state or the mechanical lock to the next step.
It is in the transition to the black state, and the toggle mechanism 6 is the injection filling resin.
Not back by pressure). (4) Injection pressure detector 66 or injection during injection filling operation
If the injection pressure or the injection speed detected by the speed detector 67 is
The respective set values set by the Rakkaji comparison control unit 64 are reached.
When it is detected, from injection filling operation to injection pressure holding operation
While switching, the second timer 63 is activated and the mold clamping side
The injection pressure and mold clamping pressure in the compression process at
U In this case, the injection pressure and injection speed detection settings
The regular procedure is the same as in injection press molding. In addition,
The second timer 63 is set in advance in the injection pressure holding process.
Injection pressure multi-step set value (p₂,
p₃...) corresponding to the timing time (t₂ , T₃・
・ ・) And start time (t_E) Is set. Well
Also, in the mold clamping compression process, the mold clamping pressure setting unit
Mold clamping pressure multi-step set value set in 71 (PP₂′, P
P₃′) Timing time (T₂′, T ₃′ ・
・ ・) And mold clamping completion time (t_E) Is set. Na
Weighing start time (t_E) And mold clamping completion time (T_E)
The setting of is the same as that of injection press molding.

(5) Timeout signal of the second timer 63
(T₂, T₃...), the injection control unit 61
The injection pressure (holding pressure) in the pressure holding process is controlled in multiple stages (t₂
= P₂, T₃= P₃...) together with the timeout signal
No. (t_E) And start preparation for the next molding.
to go into. Similarly, the timeout signal (T₂′, T₃′ ・ ・
.), For example, a timeout signal (T₂′)
When the mold is detected, the mold clamping control unit 70 controls the hydraulic control valve 67b.
Control to start the compression process. Clamping cylinder stroke
Sensor 75 detection signal (S _s) Reaches the set value (S_s
= PP₂′), Set value (PP₂′) Mold to hold
Controls the hydraulic pressure of the tightening cylinder 8 and outputs a time-out signal.
(T₃Position holding control is continued until ′) is detected. Since
After that, the above operation control is repeated and the mold clamping pressure in the compression process is
Force multi-step control and time-out signal
(T_E), The mold is opened and the product is taken out.
Then, a series of molding operations are completed.

As described above, the cooling and solidification is performed by the two-stage control means for controlling the mold clamping pressure during the injection filling operation and the synchronous control of the mold clamping pressure and the injection pressure during the injection filling behavior (injection holding pressure operation). The resin in the mold cavity, which is advancing, does not receive an excessive compression force, and there is no backflow of the resin to the injection side, and an appropriate holding pressure is exerted. As a result, it is possible to obtain a high-quality molded product that is free from external defects such as deformation, warpage, and shrinkage and internal residual stress, and has extremely small weight variation. In addition, by accurately detecting the change from the injection filling behavior to the injection filling behavior and performing the control process start timing of the compression process with high accuracy, the control system can use the simplest timer timeout signal. As a result, it is possible to obtain an extremely high quality molded product at low cost.

Therefore, if the above-mentioned injection compression molding is used, the resin pressure in the mold cavity is lowered and the bias pressure is prevented by the mold opening behavior during the injection filling, and the injection side of the proper holding pressure is applied during the compression process. By the action from both the mold clamping side, the thickness of the molded product is reduced for the purpose of cost reduction and weight saving by material cost reduction, or a colored resin layer for surface decoration of the molded product is laminated on the surface of the molded product, or A composite molded product, such as a laminated molded product, in which a resin layer containing a reinforcing material is laminated on the back surface of the molded product for reinforcement, and at the same time labor saving is added, can be easily obtained with high quality.

[0054]

As described above, in the present invention, the following excellent effects can be exhibited. (1) Inconsistency between injection and mold clamping operations due to control response delay by controlling the simultaneous operation of injection and mold clamping and the mold clamping position or mold clamping pressure in multiple stages based on the mold clamping side signal, injection side signal Since the control error factor due to the injection side, which has occurred in the case of the standard, can be completely eliminated, a high quality molded product can be stably supplied. (2) Further, after the injection pressure or the injection speed during the injection filling reaches the set value, that is, after the change in the injection filling behavior from the injection filling behavior is accurately detected, the injection holding pressure is set based on this detection signal. By performing multi-stage pressure control in the mold clamping compression process,
The stable supply of extremely high quality molded products free from external defects such as deformation, warpage and shrinkage and internal defects such as internal residual stress is further improved. (3) Further, since the detection of the mold clamping side signal as the control reference and the injection side signal during injection filling is extremely accurate, the above control can use the timeout signals of the first timer and the second timer. As a result, it is possible to realize stable supply of molded products of extremely high quality at low cost. (4) Multistage control of the mold clamping position or the mold clamping pressure during injection filling and compression process is performed on the basis of the injection cylinder stroke position corresponding to each mold clamping position and mold clamping pressure, thereby boosting the toggle mechanism. By utilizing the characteristics, it is possible to control the mold clamping position and mold clamping pressure with extremely high precision, and as a result, it is necessary to control the operation on the mold clamping side. Application development to molding can be achieved very easily, and high added value of molded products and cost reduction by process saving become possible.

[Brief description of drawings]

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

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

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

FIG. 4 is a process explanatory diagram showing a compression process start timing setting procedure according to the embodiment of the present invention.

FIG. 5 is a flowchart showing an injection compression molding operation procedure according to the embodiment of the present invention.

[Explanation of symbols]

1 End Platen 2 Fixed Plate 3 Movable Plate 4a Movable Mold 4b Fixed Mold 5 Cavity 6 Toggle Mechanism 7 Crosshead 8 Mold Clamping Cylinder 9 Piston Rod 10 Guide Rod 11 Tie Bar 20 Mold Clamping Device 40 Injection Device 60 Control Device 61 Injection Control Part 62 First timer 63 Second timer 64 Comparison control part 65 Position setting part 66 Injection pressure detecting part 67 Injection speed detecting parts 67a, 67b Hydraulic pressure control valves 68a, 68b Hydraulic pressure source 70 Mold clamping control part 71 Mold clamping pressure setting part 72 Mold clamping pressure sensor 73 Mold clamping position setting unit 74 Mold clamping position sensor 75 Mold clamping cylinder stroke sensor 100 Injection low-pressure molding machine E Advance limit K Injection pressure comparison set value M Monitoring start point P Set pressure reaching point (or mold clamping pressure) P _1, P _2, P ₃ clamping pressure Pmax maximum clamping pressure PP _1, PP _2, PP ₃ clamping pressure setpoint P _{1 ', PP 2', PP} 3 ' clamping pressure setting S ₀ origin S _1, S _2, S ₃ type clamping position SS _1, SS _2, SS ₃ Clamping position set value SS _1', SS ₂ ', SS ₃ ′ Mold clamping position set value V Set speed reaching point

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kaichiro Nakai, 1980, Okiyama, Ogushi, Ube City, Yamaguchi Prefecture, Ube Industries, Ltd., Polymer Research Laboratory (56) Reference Japanese Patent Laid-Open No. 5-237894 (JP, A) Kaihei 7-9518 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29C 45/70 B29C 45/68 B29C 45/76

Claims (5)

(57) [Claims] [Claim 1] using the injection low pressure molding apparatus for performing mold clamping by preparative <br/> guru mechanism driven by hydraulic clamping cylinders, melting between retained molds which in advance Not closed
Injection low to inject and fill resin and then compress on the mold clamping side
It is a pressure molding method, in which both molds are
From the touched state, move the mold back to the predetermined mold opening position.
And then the stroke of the mold clamping cylinder connected to the toggle mechanism.
Set the mold clamping position at the low position and start the molding operation
During the subsequent mold clamping operation, the stroke of the mold clamping cylinder is
Detects when the initial mold clamping state set by the manual setting has been reached
At the same time, the first timer is started and the set value is
Control the hydraulic pressure of the mold clamping cylinder to maintain
And, based on the plurality of time-out signal of said first timer, to initiate the injection filling operation, the mold clamping control the clamping position and clamping pressure to one-stage or multi-stage, injection pressure during injection filling operation or A feature that the mold clamping pressure and the injection pressure are controlled in one step or multiple steps based on a plurality of timeout signals of a second timer that is activated at the same time when either one of the injection speeds reaches a set value. Injection low-pressure molding method. 2. A motor driven by a hydraulic mold clamping cylinder.
Using an injection low-pressure molding machine that performs mold clamping with a guru mechanism
Injection molding of molten resin into a previously closed mold
Then, the injection low-pressure molding method in which compression is performed on the mold clamping side.
Therefore, the toggle mechanism is in the bent state and
The mold clamping pressure that allows the two molds closed by
After loading the mold, the mold clamp connected to the toggle mechanism
Molding is performed by setting the mold clamping force at the cylinder stroke position.
During the mold clamping operation after the start of operation, the mold clamping cylinder
When Trooke has reached the preset initial mold clamping state.
And the first timer is started at the same time when
The operation of the mold clamping cylinder to keep the set value.
A plurality of timeout signals of the first timer for controlling the hydraulic pressure.
The injection filling operation is started based on the
And mold clamping pressure is controlled in one or multiple stages, and injection filling is performed.
Either injection pressure or injection speed during operation
The second that is activated at the same time it detects that has reached the set value
Based on a plurality of timeout signals of the timer, mold clamping pressure
It is characterized by controlling the force and injection pressure in one or multiple stages.
Injection low pressure molding process to. 3. Injection pressure or injection speed during injection filling operation
Is detected at the forward limit of the injection cylinder stroke and
Injection within the region near the completion of injection filling up to the limit
At the injection cylinder stroke position,
Based on the set value of the injection speed of the first stage or multiple stages that has been set
When performing injection filling control based on
The detection signal within the storage range is the injection pressure and is preset
Set value of injection pressure that can be filled in the mold cavity
When performing injection filling control based on
The detection signal within the position range is the injection speed
The injection low-pressure molding method according to claim 1 or 2 . 4. The molds are touched when the molds are closed.
Is detected and the origin of the mold clamping cylinder stroke position is determined.
Stroke position of the mold clamping cylinder with the origin set
The mold clamping position and mold clamping force based on the
If the mold clamping operation is controlled based on the set value during the molding operation
Together, the mold clamping cylinder's
The hydraulic pressure is controlled to control the hydraulic pressure or the contract.
Injection low pressure molding method Motomeko 2 wherein. 5. A mold clamping position setting unit for setting mold clamping positions in multiple stages.
And the mold clamping pressure setting section that sets the mold clamping pressure in multiple stages, and
Mold clamping position sensor that detects the position and mold clamping pressure
Detects mold clamping pressure sensor and mold clamping cylinder stroke
Clamping cylinder stroke sensor and reaching the initial clamping state
The first timer that starts at the same time as
Starts as soon as the injection pressure or speed reaches the set value.
The second timer that operates and the set value of the mold clamping position setting section.
And the set value of the mold clamping pressure setting section and the mold clamping position sensor
Output signal, detection signal of the mold clamping pressure sensor, and mold clamping cylinder
Stroke sensor detection signal and the first timer and front
Mold clamping based on multiple timeout signals from the 2nd timer
Equipped with a mold clamping control unit that controls the operation, it controls the injection filling operation.
Injecting and filling operation
Pressure detection to detect the injection pressure and injection speed of each
Section and injection speed detection section, detection of injection pressure and injection speed
A position setting section for setting a range, the injection pressure detecting section, and
The second timer is set based on the detection signal of the injection speed detection unit.
At the same time as starting up, pressure control start signal is sent to the injection control unit.
Injection low-pressure molding apparatus comprising a comparison control unit for transmitting a signal .