JP3291129B2 - Post-processing start timing detection method for injection molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a post-processing start timing in an injection molding machine.

[0002]

2. Description of the Related Art A movable member for gate cutting is provided inside a mold, and after injection is completed, the resin in the mold is appropriately solidified and driven to drive the gate of the molded product before starting the mold opening. In addition, a moving member for applying pressure is provided inside the mold, and it is driven at an appropriate timing after the injection is completed, thereby applying pressure to the resin in the mold and preventing sinking of the molded product. Post-processing techniques for injection molding machines adapted to do so are known.

[0003] In the post-processing of the gate cutting, if the timing of driving the moving member is too early, the solidification of the resin is insufficient, so that the gate cutting is incomplete. Although the process itself can be performed accurately, there is a problem that the waiting time until the start of the post-processing is increased, so that the molding cycle is increased and the productivity is deteriorated. On the other hand, when the moving member is driven to apply pressure for preventing sink marks, if the timing for driving the moving member is too late, the resin solidifies more than necessary. Cannot be applied, and if the timing is too early and this operation is performed to move the moving member to the stroke end before the gate seal is completed, the moving member is driven after the gate seal is completed. There is a problem that pressure cannot be applied to the resin.

In order to solve these problems, it is necessary to accurately know the solidification state of the resin and to set the start timing of the post-processing, but until now, the solidification state of the resin in the mold has been properly adjusted. There is no means for reliably detecting the timing, and setting of the timing has been performed by trial and error depending on the intuition of the operator. For this reason, it takes a considerable amount of time to find an appropriate post-processing start timing, and the die is not satisfactorily released due to inadequate gate cutting while the post-processing failure continues. In addition, there is a risk that the molding material and working time will be wasted due to damage to the surface or sink marks.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an injection molding machine which can solve the above-mentioned disadvantages of the prior art and can quickly and surely determine a post-processing start timing suitable for a desired post-processing. An object of the present invention is to provide a method for detecting post-processing start timing.

[0006]

SUMMARY OF THE INVENTION The present invention drives a moving member for post-processing by shifting the timing for each molding cycle, and reduces a resin reaction force acting on the moving member during driving of the moving member. The above object has been achieved by a configuration in which the solidification state of the resin at each timing is detected by detecting, and a post-processing start timing corresponding to the solidification state of the resin suitable for a desired post-processing is obtained.

Further, in the post-processing start timing detecting method according to one embodiment, the timing at which the resin is completely solidified is set as an initial value of the post-processing start timing in the injection molding machine, and the post-processing start timing is advanced. The step size of the time is set in the injection molding machine in advance, and the post-processing start timing is advanced by the time step of the time in each molding cycle to perform the continuous operation of the molding operation and the post-processing, thereby reducing the set resin reaction force. The same object was achieved by detecting the post-processing start timing in the molding cycle in which is detected first.

Further, each time a molding cycle in which the reduction of the set resin reaction force is detected first is determined, the post-processing start timing in the molding cycle one cycle before the molding cycle is reset as a new initial value, The post-processing corresponding to the solidification state of the resin suitable for the desired post-processing is performed by resetting the step size of the time for accelerating the post-processing start timing to a shorter time and repeatedly performing the same processing a set number of times. The start timing can now be determined more precisely.

Further, instead of changing the post-processing start timing for each molding cycle, post-processing is performed at the same timing over a plurality of molding cycles, and the average value of the resin reaction force acting on the moving member is determined. By shifting, it is possible to remove the fluctuation of disturbance affecting the detection of the resin reaction force, and it is possible to more precisely obtain the post-processing start timing corresponding to the solidification state of the resin suitable for the desired post-processing. I did it.

[0010]

The timing at which the resin is completely solidified is set as an initial value of the post-processing start timing in the injection molding machine, and the time interval for accelerating the post-processing start timing is set in the injection molding machine. The injection molding machine performs a continuous operation of the molding operation and the post-processing by advancing the post-processing start timing by the step size of the time for each molding cycle, and in the molding cycle in which the decrease in the set resin reaction force is detected first. The post-processing start timing is detected. Each time the injection molding machine detects a decrease in the resin reaction force set on the basis of the initially detected resin reaction force, the injection molding machine newly sets the post-processing start timing in the molding cycle one cycle before the molding cycle. The initial value is reset as the initial value, and the step width for accelerating the post-processing start timing is reset to a shorter time, and the same processing is repeatedly executed for the set number of times to solidify the resin suitable for the desired post-processing. Precisely determine the post-processing start timing corresponding to the state.

Since the solidification state of the resin is detected by detecting the resin reaction force acting on the moving member while the moving member is being driven, the solidification state of the resin at various post-processing start timings is accurately known. This makes it possible to easily select the post-processing start timing corresponding to the solidified state of the resin suitable for the desired post-processing. In addition, the timing at which the resin is completely solidified is set as an initial value of the post-processing start timing, and the timing is changed only in a direction to gradually advance the post-processing start timing, so that the continuous operation of the molding operation and the post-processing is performed. Detects the optimal post-machining start timing by detecting the optimal post-machining start timing without specifying the direction to shift the timing. The time required for detection can be reduced. Further, every time a decrease in the resin reaction force set based on the resin reaction force detected first is detected, the process returns to the post-processing start timing in the molding cycle one cycle before the molding cycle, and a shorter time width In order to detect the optimal post-machining start timing, the timing is changed at short time intervals from the beginning to detect the optimal post-machining start timing. The required required time is reduced, and the optimum post-machining start timing is detected with sufficient precision as in the case where the timing is changed at short time intervals from the beginning to detect the optimal post-machining start timing. Can be. In addition, since an average value of the resin reaction force acting on the moving member is obtained by performing post-processing at the same timing over a plurality of molding cycles, the influence of the fluctuating disturbance is removed, and the solidification state of the resin is more appropriately adjusted. The post-processing start timing corresponding to the solidified state of the resin suitable for the desired post-processing can be determined more accurately.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a main mechanism of an injection molding machine according to one embodiment and a main part of a control system of the injection molding machine. Although only the periphery of the ejector mechanism is shown in FIG. 1, other components such as an injection shaft, a screw rotating shaft, a mold clamping shaft, and a mold thickness adjusting shaft are different from those of a conventional electric injection molding machine. The same is true. First, the outline will be briefly described. In FIG. 1, reference numeral 1 denotes an injection cylinder of an injection molding machine, reference numeral 4 denotes a fixed side mold attached to a fixed platen of the injection molding machine, and reference numeral 3 denotes a movable platen of the injection molding machine. The product is formed by a cavity 5 formed in a gap between the fixed mold 4 and the movable mold 3, which is a movable mold (collectively referred to as a mold) attached. As before, the molten resin injected from the injection cylinder 1 flows into the runner 6 engraved between the fixed mold 4 and the movable mold 3 via the sprue bush 9 of the fixed mold 4. Then, it enters the cavity 5 through the gate portion 7 that connects the cavity 5 and the runner 6.

A movable member 8 for cutting the gate made of a rod material or the like is slidably provided in the movable mold 3 at a position corresponding to the position of the gate portion 7. The leading end of the moving member 8 projects into and out of the gate 7 in the mold in conjunction with the movement of the board 2 toward and away from the movable mold 3. The protrusion limit of the moving member 8 is finally
When the leading end of the movable member 8 comes into contact with the parting surface of the fixed mold 4 to be in a pushed-off state, the resin of the gate portion 7 is completely sheared and is subjected to post-processing. Gate cutting work is completed.

In this embodiment, since the slide plate 2 is driven by an ejector rod provided as standard equipment provided on the movable platen, an ejector pin is further implanted or a stripper plate is continuously provided. If the ejector plate is driven by an ejector rod to perform a final product release operation, some measure is required. The gate cutting operation performed by driving the moving member 8 needs to be performed with the molds 3 and 4 closed, whereas the product release operation performed by driving the ejector pins and the like opens the molds 3 and 4. If the sliding plate 2 and the ejector plate follow the operation of the ejector rod at the same time, it is impossible to perform both the gate cutting operation and the product release operation without any trouble. . However, as can be easily assumed by those skilled in the art, such a problem can be easily solved by the following method.

The simplest method is to construct the slide plate 2 and the ejector plate separately, and to operate them substantially independently by a single ejector rod. For example, an ejector plate is disposed relatively close to the back surface of the movable mold 3, and a return spring for urging the ejector plate is interposed between the back surface of the movable mold 3 and the ejector plate to eject the ejector pin. For example, the ejector plate is biased in a direction in which the ejector plate retracts from the parting of the movable mold 3, and further, the separation limit of the ejector plate with respect to the movable mold 3 is regulated by a mechanical stopper. Further, a certain distance is provided in a direction away from the ejector plate, and the slide plate 2 is provided so that the slide plate 2 is superimposed on the ejector plate. 2 is attached.

According to this configuration, the ejector rod expands and contracts in a predetermined range from the retracted state, that is, in a range until the sliding plate 2 comes into contact with the ejector plate.
With the molds 3 and 4 closed, only the moving member 8 can be driven to perform the gate cutting operation.
If the ejector rod is projected beyond the range in the state in which the slide plate 4 is opened, the ejector plate overlapping the slide plate 2 can be driven to perform a product releasing operation using an ejector pin or the like. With this configuration, the moving member 8 projects considerably at the stage of the product release operation, but at this stage, since the movable mold 3 is already at the mold opening completion position or the position during the mold opening operation, Nothing prevents the moving member 8 from projecting, and no particular problem occurs. Naturally, it is necessary to individually set the ejector rod protrusion stroke for the gate cutting operation and the ejector rod protrusion stroke for the product release operation. This is easy in an injection molding machine equipped with a motor. M in FIG. 1 is a servomotor for an ejector shaft for controlling the amount of protrusion of an ejector rod which is provided as standard on a movable platen of an injection molding machine, and includes a pulse coder P as position detecting means. Instead of mounting the sliding plate 2 directly on the ejector rod on the movable platen side, it is possible to use a return spring specification similar to that of the ejector plate, and make only the ejecting operation of the moving member 8 be performed by the ejector rod. When the resin reaction force acting on the moving member 8 during the gate cutting operation is detected by the drive current flowing through the servomotor M or the output of the observer, in order to reduce the ratio of careless load fluctuation to the whole, It is better to eliminate elements such as springs that cause disturbance.
Of course, in the above arrangement, the return spring of the ejector plate is not compressed during the gate cutting operation.

The simplest configuration example in which the moving member 8 for the gate cutting operation and the ejector pin for the product release operation are driven by a single servomotor M has been described above. It is also possible to adopt other configurations by appropriately operating the mechanical elements and kinematics of the moving member 8. Further, by providing another motor or servomotor that drives only the moving member 8, The ejector pins and the like may be driven completely independently.

Numerical control device 1 for driving and controlling an injection molding machine
Numeral 0 has a CPU 25 for CNC which is a microprocessor for numerical control, a CPU 18 for PMC which is a microprocessor for a programmable machine controller, a servo CPU 20 which is a microprocessor for servo control, and a CPU 17 for pressure monitoring. By selecting mutual input / output via the interface 22, information can be transmitted between the microprocessors. In addition,
The pressure monitoring CPU 17 is a monitoring CPU for sampling the injection holding pressure and the screw back pressure via the A / D converter 16 and a pressure detector (not shown) on the injection screw side. As far as the example is concerned, it has nothing to do with the configuration for detecting the resin reaction force acting on the moving member 8.

A ROM 13 storing a sequence program for controlling a sequence operation of the injection molding machine and a RAM 14 used for temporary storage of operation data are connected to the CPU 18 for the PMC, and the entirety of the injection molding machine is connected to the CPU 25 for the CNC. R that stores a program or the like for dynamic control
OM27 and R used for temporary storage of operation data, etc.
AM 28 is connected.

The servo CPU 20 and the pressure monitoring CPU 17 each include a ROM 21 storing a control program dedicated to servo control, a RAM 19 used for temporary storage of data, and a control program related to the above-described pressure data sampling processing. ROM that stores
11 and a RAM 12 used for temporary storage of data are connected. Further, the servo CPU 20 includes the CPU 2
Based on a command from 0, servomotors 15 for driving servomotors M for each axis (not shown) for mold clamping, injection, screw rotation, etc., and a servo amplifier 15 for driving a servomotor M for ejector axis are connected. Each output from the pulse coder provided for the axis servomotor is fed back to the servo CPU 20. The current position and moving speed of each axis calculated by the servo CPU 20 based on the feedback pulse from the pulse coder are stored in the current position storage register of the RAM 19 and The current speed storage registers are sequentially updated and stored. Further, in this embodiment, an observer 60 for estimating the load torque acting on the servomotor M for the ejector shaft is provided, and the current value Td2 of the load torque estimated by the observer 60 is sequentially stored in the load torque of the RAM 19. The data is updated and stored in the storage register.

FIG. 8 is a schematic diagram showing the construction of an observer 60 for detecting a load torque acting on a servomotor M for an ejector shaft, that is, a value acting as a resin reaction force acting on a moving member 8 during a gate cutting operation. FIG. 3 is a functional block diagram showing In FIG. 8, u is a torque command obtained by the speed loop processing of the servo CPU 20, and the elements 52, 5
3 is an element of the transfer function of the servo motor M.
t is a torque constant of the servo motor M, J is inertia, and S is a Laplace operator. Elements 61 and 65
"B" in the above is an estimated ratio between the torque constant Kt of the servo motor M and the inertia J, that is, an estimated value of (Kt / J). K1 and K2 of elements 62 and 63 are parameters of the observer 60, S is a Laplace operator, and element 6
4 represents an integral element. When the block diagram of the observer 60 in FIG. 8 is analyzed as b = Kt / J, finally, Td2 = Td1 · (1 / b) = (Td / J) · (J / Kt)
= (Td / Kt), and an estimated value Td of (a value proportional to) the load torque Td.
2, that is, a value obtained by calculating the load torque Td in units of a torque command (current command) is obtained (by dividing Td by a torque constant, the same dimension as the torque command u is obtained).

In this way, the load torque Td applied to the ejector shaft servo motor M is determined by the process of the observer 60 at every predetermined cycle (processing cycle of the position and speed loop processing) performed by the servo CPU of the servo motor M for the ejector shaft. Member 8
Is measured and written to the RAM 19 sequentially. Since the substantial processing operation by the servo CPU 20 is described in detail in the patent application for the method of measuring the mold inner pressure filed on May 2, 1994 by the present applicant, the detailed description is omitted. As another embodiment, the resin reaction force acting on the moving member 8 can be detected by directly detecting the driving current of the servomotor M for the ejector shaft or by directly attaching a pressure detector to the moving member 8 or the sliding plate 2. It is also possible to detect.

The interface 23 is an input / output interface for receiving signals from limit switches and operation panels provided in various parts of the injection molding machine and transmitting various commands to peripheral devices of the injection molding machine. is there. A manual data input device 29 with a display is connected to the bus 22 via a CRT display circuit 26 so that a monitor display screen and a function menu can be selected and various data input operations can be performed. And various function keys.

The non-volatile memory 24 is a memory for storing molding data (injection holding pressure conditions, weighing and kneading conditions, etc.) and various set values, parameters, macro variables, and the like relating to the injection molding operation.

With the above configuration, the PMC CPU 18 controls the sequence of the entire injection molding machine, while the CNC CPU 25 performs pulse distribution to the servomotors of each axis based on the control program in the ROM 27,
U20 is a position loop control, a speed loop control, and a current loop based on a movement command distributed to each axis by pulses and a position feedback signal and a speed feedback signal detected by a detector such as a pulse coder. Control, and servo control such as observer processing are performed, and so-called digital servo processing is executed.

Hereinafter, a method of detecting a post-machining start timing in this embodiment based on the above-described configuration will be described. In this embodiment, the initial value of the post-processing start timing is delayed in advance by the elapsed time from the start of holding pressure (completion of injection), that is, the elapsed time based on the time point of completion of resin filling (at least when the resin is completely Time required for solidification), and the post-processing start timing that is optimal for the gate cutting work is automatically obtained by gradually advancing the post-processing start timing. In order to detect a more suitable post-machining start timing, the time interval for hastening is automatically switched from long to short in two stages, and the post-processing required for these processes is performed. Initial value of processing start timing and time interval Δt1 (long), Δt for hastening timing
Each of 2 (short) is stored in the nonvolatile memory 24 in advance.

As a method for detecting the resin reaction force (load torque Td2) acting on the moving member 8 during the gate cutting operation and specifying the solidified state of the resin, the moving member 8 is moved and the stroke section is determined. A method of sampling the load torque Td2 when the movable member 8 reaches the predetermined position and representing the resin reaction force Ra acting on the movable member 8 during the gate cutting operation. A predetermined time has elapsed since the movable member 8 started moving. A method of sampling the load torque Td2 at the time and representing the resin reaction force Ra acting on the moving member 8 during the gate cutting operation (in this case, the predetermined time is naturally set shorter than the time required for the entire moving movement of the moving member 8). ), Based on the average value of the load torque Td2 detected while the moving member 8 moves from the first predetermined position set on the stroke section to the second predetermined position. To represent the resin reaction force Ra acting on the moving member 8 during the gate cutting operation, and detecting the moving member 8 while moving from the first predetermined position set on the stroke section to the second predetermined position. A method of representing the resin reaction force Ra acting on the moving member 8 during the gate cutting operation by using the maximum value of the applied load torque Td2, the second method after the first predetermined time elapses after the moving member 8 starts moving. A method of representing the resin reaction force Ra acting on the moving member 8 during the gate cutting operation by the average value of the load torque Td2 detected until the predetermined time elapses (in this case, of course, the first and second predetermined Time is moving member 8
Is set shorter than the total stroke movement required time), the maximum of the load torque Td2 detected from when the first predetermined time elapses after the moving member 8 starts to move until the second predetermined time elapses. A value representing the resin reaction force Ra acting on the moving member 8 during the gate cutting operation (in this case, of course, the first and second predetermined times correspond to the moving member 8
Is set shorter than the total stroke movement required time).

Of these, what is selected as an indicator of the solidification state of the resin is arbitrary, and it may be desired to change the selection as necessary depending on the mold structure and the characteristics of the resin. Therefore, in the present embodiment, in order to satisfy such a need, the elapsed time i ·
t0 (t0 = sampling period of load torque Td2, i =
File means for storing the position Pn of the moving member 8 and the resin reaction force Rn (Rn = load torque Td2) at that time in correspondence with 0, 1, 2, 3,...
(See (a)) in the RAM 14. In addition, a subprogram (corresponding to step S14 of the process described later) for selectively performing each of the above-described methods (1) to (5) to obtain the resin reaction force Ra indicating the solidification state is stored in the ROM 13, but is stored in a file. Searching for other data by referring to the value of a specific data type, and processing for obtaining an average value and a maximum value are already known in computer-related peripheral technologies, so the content itself is not Is not specifically described.

FIGS. 2 to 5 are flowcharts showing the outline of post-processing start timing detection processing in this embodiment. In this processing, an injection molding operation for obtaining a post-processing start timing for a gate cutting operation is performed. While
This is repeatedly executed by the PMC CPU 18 every time the start of the pressure holding is confirmed, and includes the protrusion control of the moving member 8 for the gate cutting operation. After this, when the processing start timing detection processing is completed, the PMC CPU
18 returns to the normal sequence control as before,
The sequence control after the mold opening is continuously performed in the same manner as in the related art.

Then, the PMC CPU 18 which has confirmed the start of the holding pressure and started the post-machining start timing detection processing,
First, the time required from the start of the pressure holding to the time when the resin is completely solidified is set as the initial value of the standby time T0 and the timer T
(Step S1), measurement of the elapsed time by the timer T is started (step S2), and the process waits until the set time T0 elapses, that is, until the resin in the mold is completely solidified (step S1). In step S3, a rod movement start command is output to the CNC CPU 25 to start driving the ejector shaft servomotor M and start the gate cutting operation by the projecting operation of the moving member 8 (step S4).

Next, the PMC CPU 18 sets the initial value 0 to the index i used to specify the address of the file means (step S5), resets the sampling period t0 to the timer T, and sets the timer T to the elapsed time. The measurement is started (Step S6, Step S7), and the resin reaction force Rn is further measured.
The current value of (Rn = load torque Td2) and the current position Pn of the moving member 8 are stored in the RAM 19 via the servo control CPU 20.
And stored in the storage areas R (i) and P (i) of the address i in the file means (see FIG. 6A) (steps S8 and S9), and the current position Pn of the moving member 8 is set as the final target. It is determined whether the position has been reached (step S10). Needless to say, the final target position here is a value corresponding to the protruding stroke of the ejector rod for the gate cutting operation. Moving member 8
If the current position Pn does not reach the final target position,
The MC CPU 18 increments the value of the index i by 1 (step S11), waits until the set time of the timer T elapses, that is, until one sampling cycle elapses (step S12), and returns to the processing of step S6 again. Then, the same processing as described above is repeatedly executed.

As a result, a predetermined sampling period t from the start of the gate cutting operation by the projecting operation of the moving member 8
For each 0, the resin reaction force Rn currently acting on the moving member 8 and the position Pn of the moving member 8 are sampled,
The data is sequentially written to the file means.

While such processing is repeatedly executed, the position Pn of the moving member 8 reaches the final target position, and the leading end of the moving member 8 comes into contact with the parting surface of the fixed mold 4 so that the gate portion 7 When it is confirmed that the resin has been completely sheared (step S10), the PMC CPU 18
A rod return command is output to the PU 25 to rotate the servomotor M for the ejector shaft in the reverse direction, thereby returning the moving member 8 to the original position in the contracted state and terminating the gate cutting operation (step S13). ~
The sub-program is executed according to any one of the above methods to obtain the value of the representative value Ra of the resin reaction force acting on the moving member 8 during the gate cutting operation (step S14).

Next, the PMC CPU 18 determines whether or not the current value of the determination reference value storage register R is 0 (step S15), and determines the current stage immediately after the start of the injection molding operation for obtaining the post-processing start timing. Since the value of the discrimination reference value storage register R is held at the initial value 0, the discrimination result of step S15 is necessarily true. Therefore, the PMC CPU 18 calculates the resin reaction force R obtained this time.
a, that is, a determination reference value is determined based on the value of the resin reaction force Ra detected in the first gate cutting operation after the start of the injection molding operation for determining the post-processing start timing, and that value is stored in the determination reference value storage register. Update and store in R (step S16). The determination reference value R updated by this processing
Is the resin reaction force Ra detected in the first gate cutting operation.
From the value obtained by subtracting the set value α of the resin reaction force corresponding to the maximum allowable range of the decrease in the hardness of the resin in which the gate cut can be appropriately performed. As already described in the section of the prior art, in the case of performing post-processing of gate cutting, there is a problem that gate cutting is incomplete if resin is insufficiently solidified. Therefore, in the case of this embodiment, the driving force of the moving member 8 required to shear the resin completely solidified by the above-described processing, that is, the resin actually acting on the moving member 8 when the completely solidified resin is sheared The reaction force Ra is determined first, and the set value α is subtracted from the value to obtain a resin reaction force R corresponding to the lower limit of the hardness of the resin capable of appropriately performing gate cutting, that is, a determination reference value. Find R. In this case, needless to say, the value of the set value α corresponds to a decrease in the set resin reaction force.

The PMC CPU 18 which has determined the reference value R
Then, the above-mentioned larger step width setting value Δt1 is set in the step width storage register ΔT for storing the step width of the time for advancing the post-processing start timing (step S17), and the value of the standby time T0 is set. The standby time of the gate cutting operation in the next molding cycle is shortened by updating the setting to T0-ΔT (step S19), the processing start timing detection processing is terminated after this cycle, and the process returns to the normal sequence control, and After the opening, the sequence control is continuously performed in the same manner as in the related art. When all the sequence controls for one molding cycle are completed, the sequence control for the next molding cycle is started.

Then, when the start of the holding pressure is confirmed again,
The PMC CPU 18 starts the post-processing start timing detection processing in the same manner as described above. Step S in the previous cycle
Since the update setting operation relating to the standby time T0 is performed in the process of No. 19, the gate cutting operation starting with the output of the rod movement start command is naturally performed at a timing earlier by ΔT (= Δt1) than the previous molding cycle. Will be started. Hereinafter, the PMC CPU 18 repeatedly executes the same processing as described above to obtain the value of the resin reaction force Ra applied to the moving member 8 during the current gate cutting operation (steps S1 to S14). .

The PMC CPU 18 calculates the value of the resin reaction force Ra acting on the moving member 8 during the current gate cutting operation.
Next, it is determined whether or not the current value of the determination reference value storage register R is 0 (step S15), and the determination reference value of R> 0 is already set in the determination reference value storage register R. Therefore, the result of the determination in step S15 is false, and the PMC CPU 18 determines that the resin reaction force R
whether the value of a is smaller than the determination reference value R, that is,
It is determined whether the hardness of the resin is lower than a range in which gate cutting can be appropriately performed (step S18). If the value of the resin reaction force Ra is equal to or greater than the determination reference value R, it is possible to perform a normal gate cutting operation even if the hardness of the resin is reduced by setting the standby time for starting the gate cutting operation to be shorter. Means that
The PMC CPU 18 sets the standby time T0 in the same manner as described above.
Is reduced to T0−ΔT (ΔT = Δt1) (step S19), and the processing start timing detection processing after this cycle is ended.

During the repetitive execution of the injection molding operation and the accompanying gate cutting operation, the value of the standby time T0 is eventually shortened more than necessary, and the post-processing start timing detection processing is performed. Comes when the result of the determination in step S18 is true (when a decrease in the set resin reaction force is first detected).

For example, as shown in FIG. 7 (b), the waiting time T0, which is the initial value of the time required from the start of the pressure holding until the resin is completely solidified, is set to a step width ΔT (= Δ
If the length is gradually reduced at t1), a certain point (FIG. 7B)
In the example of (1), the value of the resin reaction force Ra becomes smaller than the determination reference value R at T0 ₅ ), and the hardness of the resin becomes lower than a range in which gate cutting can be appropriately performed. The gate cutting operation can be properly performed only when the value of the resin reaction force Ra is larger than the determination reference value R.
When the step width of T (= Δt1) is large, naturally, Ra
Standby time T0 when <R (see FIG. 7B)
In the example of (1), it is inappropriate to select T0 ₅ ) as the standby time of the post-processing start timing. In addition, the value of T0 when the value of the resin reaction force Ra matches the determination reference value R (the gate cut is appropriately performed) If the step width ΔT (= Δt1) is set to be too short in order to accurately detect the waiting time T0 (the minimum value in the range in which the operation can be performed), a considerable number of times will be required until the optimum waiting time T0 is detected. The molding cycle must be repeated and time is wasted. In order to solve such a problem, the step size (Δt
After the standby time is shortened in 1) and T0 that satisfies Ra <R is obtained, the step width ΔT is reset to a shorter value (Δt2), and the interval in which the phenomenon of Ra <R occurs It is reasonable to strictly detect the change in Ra only in the vicinity and obtain the value of T0 when the value of the resin reaction force Ra substantially matches the determination reference value R. When the standby time is shortened by the rough step width ΔT (= Δt1), it is difficult to predict in advance at which point Ra <R occurs.
After actually detecting the point in time at which Ra <R based on the coarse step width (Δt1), the process returns to the standby time of the previous cycle that satisfies the condition of Ra> R, and the standby time is used as an initial value to set a small step width ΔT By repeating the same process while gradually reducing the standby time by (= Δt2), the value of T0 when the value of the resin reaction force Ra substantially matches the determination reference value R is determined.

When it is detected from the result of the determination in step S18 that the value of the resin reaction force Ra has fallen below the determination reference value R, the PMC CPU 18 first determines whether or not the switching completion flag F has been set. That is, it is determined whether or not the switching operation of the step width ΔT has been completed (step S20). Since the flag F is in an unset state in the initial stage, the determination result when the process of step S20 is first performed is naturally true. Therefore, CP for PMC
U18 resets the smaller step width setting value Δt2 in the step width storage register ΔT (step S21), and adds the value of Δt1−ΔT (ΔT = Δt2) to the current value of the standby time T0, (a gate cut sufficiently possible to appropriately make a waiting time, in the example of FIG. 7 (b) corresponds to T0 ₄₎ waiting time in the previous molding cycle is shortened only from ΔT (ΔT = Δt2) The standby time obtained is determined and updated as the standby time T0 in the next molding cycle (step S22).
Is set (step S23), and the post-machining start timing detection processing is terminated. The standby time T0 set at this time is a new initial value when the standby time is reduced by the step width Δt2. Then CPU1 for PMC
8 returns to the normal sequence control, continues the sequence control after opening the mold in the same manner as before, and when all the sequence control for one molding cycle is completed, starts the sequence control for the next molding cycle. I do.

Then, when the start of the holding pressure is confirmed again,
The PMC CPU 18 starts the post-machining start timing detection processing in the same manner as described above, but since the update setting work related to the standby time T0 has been performed in the processing of steps S21 and S22 in the previous cycle, the rod movement naturally starts. The gate cut operation that starts with the output of the command takes ΔT compared to the standby time of the previous molding cycle before that, that is, the standby time that is sufficient to perform the gate cut properly.
(= Δt2), which is started at a slightly earlier timing. Thereafter, the PMC CPU 18 repeatedly executes the same processing as described above to obtain the value of the resin reaction force Ra applied to the moving member 8 during the current gate cutting operation (above, steps S1 to S14), and step S15. After the determination processing of (1), it is determined whether or not the value of the resin reaction force Ra obtained this time is lower than the determination reference value R (step S18). If the value of the resin reaction force Ra is equal to or greater than the determination reference value R, the standby time for starting the gate cutting operation can be set even shorter, so that the PMC CPU 18 sets the value of the standby time T0 in the same manner as described above. To T0−ΔT (ΔT = ΔT
t2) (Step S19), the post-machining start timing detection processing of this cycle is terminated, and thereafter, the injection molding work and the gate cutting work accompanying it are repeatedly executed in the same manner as described above.

While the injection molding operation and the accompanying gate cutting operation are repeatedly executed in this manner, the determination result of step S18 becomes true again, and
A time point T0 at which the value of the resin reaction force Ra falls below the determination reference value R is detected (corresponding to the time data at point A in the example of FIG. 7B). Then, the PMC CPU 18 again determines whether or not the switching completion flag F has been set (step S20). In this case, since the switching completion flag F has already been set, the determination result in step S20 is false. Become. This is because the waiting time T sufficiently approximates the minimum value of the waiting time in a range where the gate cut can be appropriately performed.
0 means that a minute step width due to Δt2 is detected as a unit, and there is no problem in using the standby time T0 at this time as the optimal post-processing start timing for the gate cutting operation. Absent. Therefore,
The PMC CPU 18 sets the standby time T0 at this time.
Is displayed on the manual data input device 29 with a display as the optimum post-processing start timing for the gate cutting operation to notify the operator, and the value is stored as the post-processing start timing (step S24). This is used as the waiting time for the gate cutting work. Once the standby time T0 is determined, there is no need to obtain it again. Therefore, in the subsequent processing cycle, the standby processing in steps S1 to S3 and the output of the gate cut work start command in step S4 and the step S4 will be described.
Only the waiting process for waiting for the completion of the gate cutting operation corresponding to 10 and the returning process of the moving member 8 in step S13 may be performed.

Strictly speaking, Ra <R has already been reached when the final T0 is obtained (corresponding to the reaction force data at point A in FIG. 7B). Δt2
In view of the point that the step width is sufficiently small and that the hardness of the resin does not actually fluctuate significantly due to a slight difference in cooling time, the optimum standby time that may occur with Δt2 as the upper limit is considered. Can be ignored. If the user is concerned about this point, a value obtained by adding Δt2 to the finally obtained value of T0 by the same method as in step S19 described above is used as the optimum standby time T.
0 and stored in the process of step S24,
What is necessary is to satisfy the linguistic condition regarding T0, that is, "the minimum value of the waiting time within a range in which the gate cut can be appropriately performed".

Contrary to the above-described embodiment, it is theoretically possible to set the initial value of the standby time T0 to be short and gradually extend the initial value to obtain the optimum post-machining start timing T0. In such a case, the possibility of gate cut failure is significantly increased in a product molded before the detection of the optimum post-processing start timing T0, and a mold or injection mold caused by a mold release failure or the like is generated. In order to prevent damage to the molding machine, it is necessary for the operator to constantly monitor the injection molding machine. Therefore, when obtaining the post-processing start timing for the gate cutting work,
Set the waiting time as the initial value of the time required to completely solidify the resin or a longer time (especially if the time required for completely solidifying the resin is unknown) However, the most rational method is to shorten this as much as possible to reduce the time required for the molding cycle (of course, post-processing other than gate cutting, for example,
Other methods may be more reasonable when obtaining a post-processing start timing for performing post-processing or the like for preventing sink marks).

In the above-described embodiment, the resin reaction force when shearing the completely solidified resin is taken as a reference, and from this reference value, the maximum allowable range of the decrease in the hardness of the resin in which gate cutting can be appropriately performed is determined. The determination reference value R is obtained by subtracting the corresponding resin reaction force set value α.
May be set in the control device 10 from the beginning as the determination reference value R.

Since the set value α of the resin reaction force corresponding to the maximum allowable range of the decrease in the hardness of the resin in which the gate cut can be appropriately performed differs depending on the type of the resin, the gate diameter, etc. It is not always easy to accurately determine in advance. However, generally speaking, in the relationship between the cooling time and the solidification state of the resin, as shown in the example of FIG. 7B, if the cooling time is gradually increased, the Although the hardness also gradually increases, there is a limit point that the hardness of the resin does not increase even if the cooling time is prolonged beyond a certain time point, so by setting the value of α as a relatively small value, in general, Good results can be obtained. A simple example is the case where the initial standby time is set to be considerably longer than the time required for complete curing of the resin. In this case, the waiting time after the resin is completely cured is completely wasteful and has only an adverse effect of extending the molding cycle, but the setting value α is set to a severe value and the processing of the above-described embodiment is performed. For example, the standby time required for complete curing of the resin is accurately detected, and all unnecessary standby time after complete curing can be omitted. Of course,
As long as there is no problem even if the gate cutting operation is performed before the resin is completely cured, the value of α can be set to a somewhat large value.

In the above-described embodiment, the resin reaction force Ra is determined each time one molding cycle and post-processing are completed, and the value is compared with the determination reference value R to determine the solidification state of the resin. The standby time T0 was shortened according to the result, but several molding cycles and post-processing were performed without changing the standby time T0, and the resin reaction force Ra was measured each time. The average value of the resin reaction force Ra obtained by the cycle and the post-processing may be obtained and compared with the determination reference value R, and the standby time T0 may be reduced according to the determination result. In this way, by sampling the resin reaction force Ra a plurality of times with the same standby time and obtaining the average value, it is possible to remove the influence of the fluctuating disturbance and more accurately determine the solidification state of the resin.

Such processing can be easily implemented by adding some steps to the processing of the above embodiment as shown in FIGS. As an example, an embodiment in which N molding cycles and post-processing are performed with the same standby time to obtain the average of the resin reaction forces Ra1 to RaN will be described.

In this case, first, step S in the above embodiment is performed.
Before 1, the process of incrementing the counter j of the initial value 0 by 1 (step s01), the process of determining whether or not the value of the counter j matches N (step s02), If they match, a process of resetting the counter j to 0 (step s03) is inserted, and if it is determined in step s02 that the value of the counter j does not match N, the process of step s03 is completed. In this case, the process after step S1 of the above embodiment is started, and in the process of step S14, after the value of the resin reaction force Ra is obtained in the same manner as in the above embodiment, the value is further stored in the register Ra (j). (J = 0 to j = 0
N-1).

Therefore, the resin reaction force Ra obtained in the first post-processing with the same standby time is stored in the register Ra (1).
Similarly, the resin reaction force Ra obtained in the second post-processing of the same standby time is stored in the register Ra (2), and the resin reaction force Ra obtained in the third post-processing of the same standby time is stored in the register Ra.
(3) is stored as..., And the resin reaction force Ra obtained in the last post-processing with the same standby time, ie, the N-th post-processing with the same standby time, is stored in the register Ra (0). Will be.

Accordingly, step S1 of the above embodiment is further performed.
4 between the processing of step S15 and the processing of step S15.
Is inserted (step s04) to determine whether or not the value of the counter j is equal to 0. If the value of the counter j is equal to 0, [Ra (1) + Ra (2) + Ra (3) +.・ ・ ＋
An arithmetic expression of Ra (N-1) + Ra (0)] / N is executed to calculate an average value Ra of the resin reaction force and store it in the register Ra (step s05).
Step 5 is executed while the processing after step 5 is executed.
If it is determined in the determination process of step 04 that the value of the counter j does not match 0, steps s05 and S
The processing after 15 is canceled to terminate the post-machining start timing detection processing in the cycle.

As a result, N molding cycles and post-processing are performed in the same standby time, and at the completion of the last post-processing, the average value R of the resin reaction force in the N post-processings up to that time is obtained.
a is obtained, and it is determined whether the standby time is reduced or the detection of the optimum timing is completed according to the relationship between the average value Ra and the determination reference value R.

As described above, the control unit 1 automatically determines the optimum standby time, which is the processing start timing after the gate cutting operation.
Although the embodiment in which the setting is automatically set to 0 has been described, the data for obtaining the optimum standby time may be displayed on the manual data input device 29 with a display, and the optimum standby time may be obtained by the judgment of the operator. . For example, Step S1 to Step S in the above-described embodiment
Only the processing of step 14 and step S19 are repeatedly executed, and the relationship between the post-processing start timing (standby time from the start of pressure holding to the start of gate cutting) T0 in each molding cycle and the resin reaction force Ra is shown in FIG. 7A. 7B, the operator can display the graph on the manual data input device 29 with a display as shown in the example of FIG. 7B. T0 can be determined. In this case, since the relationship between the post-processing start timing and the solidification state of the resin (resin reaction force) can be directly visually confirmed, the maximum allowable range of the decrease in the hardness of the resin in which gate cutting can be appropriately performed. Even if you do not know what (α mentioned above), due to the change in the slope of the graph,
It is possible to relatively easily detect the minimum value of the standby time in which the gate cut can be appropriately performed. Also, at this time, instead of the automatic shortening process of the standby time as seen in step S19, the operator himself / herself can set T0.
May be manually changed.

Further, data detected during the gate cutting operation in each molding cycle, that is, the elapsed time after the start of the movement of the moving member 8, the position of the moving member 8, and the moving member 8
A graph showing the relationship between the elapsed time after the start of movement and the resin reaction force is displayed for each molding cycle, for example, as shown in FIG.
The optimum standby time T0 can also be determined by superimposing and displaying the standby time and observing the change in the slope of the graph between molding cycles having different standby times. In other words, the point in time when the slope of the graph starts to change when the standby time is gradually reduced is the point in time when the resin reaction force changes significantly, that is, the point in time when the ease of resin shearing changes.

The control unit 1 automatically determines the optimum standby time and
It is also possible to easily carry out the graph display as shown in FIGS. 6B and 7B while performing the processing as shown in FIGS. 2 to 7 for automatically setting to 0. It is.

[0056]

According to the present invention, the solidification state of the resin is detected by detecting the resin reaction force acting on the moving member while the moving member is being driven. The solidification state of the resin can be accurately known, and the post-processing start timing corresponding to the solidification state of the resin suitable for the desired post-processing can be easily selected. In addition, the timing at which the resin is completely solidified is set as an initial value of the post-processing start timing, and the timing is changed only in a direction to gradually advance the post-processing start timing, so that the continuous operation of the molding operation and the post-processing is performed. Detects the optimal post-machining start timing by detecting the optimal post-machining start timing without specifying the direction to shift the timing. The time required for detection can be reduced. Further, each time a decrease in the resin reaction force set on the basis of the resin reaction force detected based on the state in which the resin is completely solidified is detected, the post-processing start timing in the molding cycle one cycle before the molding cycle. In order to detect the optimal post-machining start timing by shortening the timing in a shorter time width and trying to detect the optimal post-machining start timing by changing the timing at short time intervals from the beginning The required time required to detect the post-machining start timing is shorter than in the case, and the optimum post-machining is performed in the same way as when detecting the optimal post-machining start timing by changing the timing at short time intervals from the beginning. The start timing can be detected sufficiently accurately. In addition, since an average value of the resin reaction force acting on the moving member is obtained by performing the post-processing at the same timing over a plurality of molding cycles,
The fluctuation of disturbance affecting the detection of the resin reaction force is removed, and the post-processing start timing corresponding to the solidified state of the resin suitable for the desired post-processing can be obtained more precisely.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a main mechanism and a main part of a control system of an injection molding machine according to an embodiment to which a method of the present invention is applied.

FIG. 2 is a flowchart showing an outline of post-processing start timing detection processing in the embodiment.

FIG. 3 is a continuation of the flowchart showing an outline of post-processing start timing detection processing.

FIG. 4 is a continuation of the flowchart showing an outline of post-processing start timing detection processing.

FIG. 5 is a continuation of the flowchart showing the outline of post-processing start timing detection processing.

FIG. 6 is a diagram showing an example of file means and data display.

FIG. 7 is a diagram showing an example of file means and data display.

FIG. 8 is a functional block diagram showing a configuration of an observer for detecting a resin reaction force acting on a moving member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Injection cylinder 2 Sliding plate 3 Movable mold 4 Fixed mold 5 Cavity 6 Runner 7 Gate 8 Moving member 10 Numerical controller 18 PMC CPU 20 Servo CPU

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-155715 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/00-45/84

Claims (6)

(57) [Claims] 1. An injection molding machine in which after a mold is filled with a resin, a moving member provided inside the mold is driven to perform post-processing on the resin inside the mold. Driving the moving member at a different timing to detect the solidification state of the resin at each timing by detecting a resin reaction force acting on the moving member while the moving member is being driven, and performing desired post-processing. A post-processing start timing detecting method in an injection molding machine, wherein a post-processing start timing corresponding to a suitable solidification state of a resin is obtained. 2. An injection molding machine in which after the filling of the mold with the resin is completed, a moving member provided inside the mold is driven to perform post-processing on the resin inside the mold. driving said moving member at the same timing over the, and facilities the post-processing, during driving of the moving member
By the work of the resin reaction force acting on the movable member is detected each time obtaining the solidification state of the resin by obtaining the average of the resin reaction force corresponding to the timing, carried out by changing the sequential the timing A post-processing start timing detection method for an injection molding machine, wherein a solidification state of a resin at each timing is obtained, and a post-processing start timing corresponding to a solidification state of the resin suitable for a desired post-processing is obtained. 3. A timing at which the resin is completely solidified is set as an initial value of the post-processing start timing in the injection molding machine, and a time interval for accelerating the post-processing start timing is set in the injection molding machine in advance. The post-processing start timing is advanced by the time interval of each cycle, and the continuous operation of the molding operation and the post-processing is performed, and the post-processing start timing in the molding cycle in which the decrease in the set resin reaction force is first detected is set. The post-processing start timing detection method for an injection molding machine according to claim 1, wherein the post-processing start timing is obtained by detecting the post-processing start timing. 4. A timing at which the resin is completely solidified is set in the injection molding machine as an initial value of the post-processing start timing, and a time interval for accelerating the post-processing start timing is set in the injection molding machine in advance. The post-processing start timing is advanced by the predetermined time for each molding cycle and the continuous operation of the predetermined number of molding operations and post-processing is performed, and the average of the resin reaction force at the same timing is performed. 3. The post-processing start timing detection method for an injection molding machine according to claim 2, wherein a post-processing start timing is obtained by calculating a value and detecting a post-processing start timing when the average value decreases by a set amount. 5. A post-processing start timing detecting method in an injection molding machine comprising the following steps. Step 1. A step of setting the timing at which the resin is completely solidified in the injection molding machine as an initial value of the post-processing start timing, and setting the time interval for accelerating the post-processing start timing in the injection molding machine. Step 2. The post-processing start timing is advanced by the time interval set for each molding cycle, the molding operation and the post-processing are continuously performed, and the moving member for the post-processing is driven .
A step of detecting a resin reaction force acting on the moving member while the moving member is being driven, and obtaining a molding cycle in which a decrease in the set resin reaction force is first detected. Step 3. The post-processing start timing in the molding cycle one cycle before the molding cycle obtained in step 2 is reset as a new initial value, and the step width for accelerating the post-processing start timing is reset to a shorter time. Process. Step 4. A step of repeatedly executing the steps 2 and 3 a set number of times. Step 5. A step of obtaining a post-processing start timing based on the post-processing start timing of the molding cycle detected in the step 4; 6. A post-processing start timing detecting method in an injection molding machine comprising the following steps. Step 1. A step of setting the timing at which the resin is completely solidified in the injection molding machine as an initial value of the post-processing start timing, and setting the time interval for accelerating the post-processing start timing in the injection molding machine. Step 2. Every time a predetermined number of molding cycles are performed, the post-processing start timing is advanced at the set step width, and the continuous operation of the molding operation and the post-processing is performed, and the moving member for the post-processing is driven for each molding cycle , Detecting and temporarily storing the resin reaction force acting on the moving member during the driving of, the average value of the resin reaction force in the predetermined number of molding cycles,
A step of obtaining a post-processing start timing when the average value decreases by a set amount. Step 3. The post-processing start timing applied immediately before the post-processing start timing obtained in step 2 is reset as a new initial value, and the step width of the time for accelerating the post-processing start timing is reset to a shorter time. Process. Step 4. A step of repeatedly executing the steps 2 and 3 a set number of times. Step 5. A step of obtaining a post-addition start timing based on the post-processing start timing detected in step 4;