JPH05286008A - Gate seal completion detecting method in injection molding machine - Google Patents

Abstract

PURPOSE:To precisely detecting completion of gate seal to enhance operation efficiency by a method wherein advancing speed of a screw is detected in a holding process of injection to compare the detected speed with a set value to detect the completion of sealing of a gate at the time at which the advancing speed of the screw has become lower than the set value. CONSTITUTION:Advancing speed Va of a screw in a holding process of injection is compared with set value Vmi of screw advancing speed, at which sealing of gate is completed. Whether or not the speed Va is lower than the value Vmi is determined as follows. Whether or not resin in a mold cavity and resin in a runner and an injection cylinder is compressed by a screw or whether or not only resin in the runner and injection cylinder is compressed by the screw is judged. And whether or not a gate separating the resin in the cavity from the runner is sealed is judged. Thereafter at the time when Va<=Vmi, it is judged that the sealing of the gate has been completed and a signal of completion of holding process is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gate seal completion detecting method for an injection molding machine.

[0002]

2. Description of the Related Art A performance evaluation of a molding cycle of an injection molding machine is generally displayed as a dry cycle time when an idle operation is performed at a maximum speed without a load. It is just catalog data showing the speed,
In actual injection molding work, the time required for resin filling and gate sealing further greatly affects the length of the molding cycle. The time required for the gate seal depends on the solidification state of the resin around the gate.If the holding pressure is released while the gate seal is incomplete, the filling resin contracts and sinks or foams volatile components. Since bubbles tend to be generated, it is necessary to maintain the holding pressure at least until the gate seal is completed, and the mold opening operation cannot be performed during this period.

[0003]

Therefore, in order to efficiently carry out the actual injection molding work, it is necessary to accurately detect the timing of the gate seal and shift to the next step.
Until now, no means has been developed to detect the timing of the gate seal, and if the holding time is unduly shortened, there is a risk of sink marks and bubbles as mentioned above. The tendency is to estimate the required time longer than necessary, and as a result of reflecting this in the setting of the pressure holding time and cooling time, the cycle time of the injection molding work is increased and the problem that the efficient injection molding work cannot be performed. there were.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and detect the completion of gate seal properly to perform efficient injection molding work. To provide a method.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the value of the screw advancing speed which should be regarded as the completion of the gate seal is stored in advance in the controller of the injection molding machine as a set value, and the screw in the injection pressure holding step is also stored. The object was achieved by successively detecting the advancing speed and comparing it with the set value, and detecting when the screw advancing speed fell below the set value as the gate seal completion.

Further, the value of the screw advancing speed which should be regarded as the completion of the gate seal is made to correspond to the molding conditions such as the holding pressure and the type of resin used which influence the screw advancing speed in advance in the controller of the injection molding machine. By storing a plurality of values and selecting a set value to be compared in accordance with the set molding conditions, it is possible to accurately detect the completion of the gate seal even when the molding conditions change.

Furthermore, by measuring the time from the start of injection to the completion of gate sealing and displaying it on the display, the holding pressure can be set accurately, and a holding pressure completion signal is output when the gate sealing is completed. By doing so, the injection pressure holding step is rounded up at an appropriate timing so that the processing of the next step can be started.

[0008]

The value of the screw advancing speed that should be regarded as the completion of the gate seal is stored in advance as a set value in the control device of the injection molding machine in association with the molding condition that affects the screw advancing speed.

When the injection pressure-holding process is started, the control unit of the injection molding machine starts timing of the gate seal time, detects the screw advancing speed sequentially, and compares it with the set value corresponding to the current molding conditions. , The time when the screw forward speed falls below the set value is detected as the completion of the gate seal.

The control device which has detected the completion of the gate seal is
The timed time at this point is displayed on the display, and a pressure holding completion signal is output to permit the start of the next step.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a main part of an injection molding machine of an embodiment to which a gate seal detecting method of the present invention is applied. Reference numeral 1 is a screw, and reference numeral 2 is an injection servomotor for driving the screw 1 in an axial direction. Is. A pulse coder 3 is attached to the injection servomotor 2 to detect the current position of the screw 1. The injection pressure is detected by the resin reaction force acting on the screw 1 in the screw axial direction. A pressure sensor 4 is provided.

A control device 100 of an injection molding machine is a microprocessor for numerical control (hereinafter referred to as NC CPU) 1
12 and a microprocessor for programmable machine controller (hereinafter referred to as PMC CPU) 114, and the PMC CPU 114 stores a sequence program or the like for controlling the sequence operation of the injection molding machine.
The OM 117 and the PMC RAM 110 are connected. The NC CPU 112 has a ROM 115 storing a management program for controlling the injection molding machine as a whole and a servo for driving and controlling servo motors for each axis such as clamp, screw rotation, ejector (not shown) and injection. The circuits are connected via the servo interface 111. In FIG. 1, only the servo circuit 103 for the injection servo motor 2 is shown.

Reference numeral 105 designates a non-volatile shared RAM composed of a bubble memory or a CMOS memory, including a memory section for storing NC programs for controlling each operation of the injection molding machine, injection speed, holding pressure, etc. And a setting memory unit for storing the setting values of various molding conditions, parameters, macro variables, etc., in which the setting values of the screw advancing speed, which should be regarded as the completion of the gate seal, are variously molded. A set value storage file is provided for storing a plurality of values corresponding to the conditions. Reference numeral 113 is a bus arbiter controller (hereinafter referred to as BAC).
CPU 112 and PMC CPU 114, shared RA
Each bus of the M105, the input circuit 106, and the output circuit 107 is connected, and the bus used is controlled by the BAC 113. The injection servo motor 2 is connected to the servo circuit 103, the torque limit value from the output circuit 107 and the detection output from the pulse coder 3 are input to the servo circuit 103, and the current position storage register in the servo circuit 103 The current position of the screw 1 is sequentially detected. The RAM 104 is for temporary storage of data.

Reference numeral 119 denotes an operator panel controller 1
Manual data input device with CRT display device (hereinafter referred to as CRT / MDI) connected to BAC 113 via 16
Various setting screens and work menus are displayed on the display screen of the CRT, and various setting data can be input and setting screens can be selected by operating various operation keys.

An address generator 118 is connected to the output circuit 107, and the same address of the RAM 108 and the RAM 109 is designated by an address command from the address generator 118. Of these, RA
M108 stores the output signal of the pressure sensor 4 converted by the A / D converter 101 as the current injection pressure, and RA
M 109 stores the up / down-counted detection signal from the pulse coder 3 as the current position of the screw 1 in the counter 102. The address generator 118 receives the sampling start signal output from the output circuit 107 at the start of injection and specifies the head addresses of the RAM 108 and the RAM 109, and thereafter, at predetermined sampling cycles until the injection pressure-holding process is completed. RAM 108 and RA
The current injection pressure and the current screw position at each sampling time are temporarily stored in the corresponding address of M109. The sampling data obtained by this processing is used as display data for a high-speed monitor mode that displays changes in injection pressure and screw position in time series.

In the above configuration, the shared RAM 1
Based on the NC program stored in 05 and various molding conditions, the sequence program stored in the ROM 117, etc., the CPU 114 for PMC performs sequence control, while the CPU 112 for NC servo-interfaces to the servo circuit of each axis of the injection molding machine. Pulses are distributed via 111 to drive and control the injection molding machine, and the control system of the entire injection molding machine is the same as the conventional one.

Next, in order to easily understand the function and effect of this embodiment, the relationship between the screw advancing speed and the gate seal in the injection pressure-holding step, which is the basic principle of the present invention, will be described.

First, when the forward movement of the screw 1 is started by an injection start command, the screw 1 injects a pre-measured molten resin from the tip of the cylinder and starts filling the molten resin into the injection molding die. Since the large resistance does not act on the screw 1 until the filling of the molten resin is completed, the advancing speed of the screw 1 in the injection stage is very high.

When the injection molding die is completely filled with the molten resin and a substantial pressure-holding operation is started, the reaction force of the molten resin directly acts on the screw 1. Although it is slower than the advance speed in the injection stage, at the stage immediately after the completion of filling, the molten resin left as a cushion amount at the tip of the cylinder and the resin in the runner of the injection mold and the mold cavity are both melted. So
The screw 1 can continue to advance while compressing these molten resins.

Then, after a lapse of time from the completion of filling, the molten resin in the injection molding die gradually cools and solidifies,
The molten resin solidifies the earliest in the portion of the gate that constitutes the minimum diameter-reduced portion of the resin path.

The resin used as the injection molding material remains the elastic body in the molten state and the solidified state, and it is theoretically possible to compress the resin, but at the stage when the gate seal is completed. Since the resin solidified in the gate portion completely blocks the gate, the phenomenon that the resin in the mold cavity is compressed does not occur. Therefore,
Only the molten resin left as a cushion amount at the tip of the cylinder and the semi-solidified resin filled in the runner of the injection mold can be compressed. Therefore, compared with the stage before the completion of the gate seal, the volume of the compressible resin is reduced by the volume of the mold cavity, and the forward speed of the screw 1 for compressing the resin and advancing the state is the state before the completion of the gate seal. Significantly slower than.

The time required from the completion of the filling of the molten resin to the completion of the gate seal itself varies in a complicated manner depending on various conditions such as the melting temperature of the resin, the mold temperature, the gate diameter and the type of resin. Although it is very difficult to calculate theoretically, the qualitative characteristics as described above, that is, the volume of the resin that can be compressed by the screw 1 greatly changes depending on the presence or absence of the gate seal.
The presence or absence of the gate seal can be detected based on the fact that the advancing speed of the screw 1 that advances the resin by compressing the resin also decreases as the volume of the compressible resin decreases.

That is, the basic idea of the present invention is to directly detect the decrease of the volume of the resin which can be compressed by the change of the screw advancing speed after the completion of filling, that is, the presence or absence of the gate seal itself. It does not attempt to predict the gate seal time arithmetically. Therefore, although factors such as the melting temperature of the resin, the mold temperature, and the gate diameter do not affect the detection accuracy in particular, the advancing speed itself of the screw 1 changes when the holding pressure setting is significantly different. In some cases, it is possible to obtain a more desirable detection result by setting the value of the screw advancing speed that should be regarded as the completion of gate sealing in correspondence with each set holding pressure.

FIG. 3 is a conceptual diagram showing an example of a set value storage file provided in the setting memory section of the shared RAM 105. In this embodiment, the gate seal is associated with the holding pressure that affects the screw advancing speed. The screw forward speed value, which is the criterion for completion, is set.

Ph0 to Ph1 and Ph1 to P in FIG.
Each of h2, ..., Phn-1 to Phn indicates the allowable range of the holding pressure at which the same screw advancing speed can be used as the criterion for determining the completion of the gate seal. 1 for each screw forward speed set value Vm1, Vm2, ..., Vmn-1, Vmn
Is remembered.

The screw forward speed set values Vm1, Vm2, ...
Since the values of mn-1 and Vmn are set in the set value storage file, the total volume of the molten resin that can be compressed immediately after the completion of filling is set under standard measuring conditions and the nozzle of the injection cylinder is sealed. Then, the standard holding pressure (Ph0 + Ph1) / 2, (Ph1 +) that represents the allowable width of each holding pressure
Ph2) / 2, ..., (Phn-1 to Phn) / 2 are applied, the forward speed of the screw 1 is measured in advance for each holding pressure, and the measured value or the measured value is further measured. A value in which a predetermined error width is set is input in advance to the setting memory unit of the shared RAM 105 via the CRT / MDI 119.

FIG. 2 shows the PMC during drive control of the injection molding machine.
9 is a flowchart showing an outline of a “gate seal detection process” that the CPU 114 for use repeatedly executes at predetermined intervals based on the control program of the ROM 117. Hereinafter, the gate seal completion detecting method in the present embodiment will be described with reference to this flowchart. .. The predetermined cycle here is one processing cycle in program management using a so-called multiple programming or time sharing technique, and its execution cycle is extremely short.

The PMC CPU 114, which has started the "gate seal detection process" for each predetermined period, first executes the injection pressure maintaining process set by the injection start signal output from the NC CPU 112 at the start stage of the injection pressure maintaining process. It is determined whether or not the "gate seal detection process" of the current cycle is a process in which the injection pressure holding process is being executed depending on whether or not the flag is already set (step S1). Is not processing during the injection pressure holding process, PM
CPU 114 for C is a substantial "gate seal detection process"
Is not executed and the processing cycle integration counter t and the display completion flag F are initialized (steps S13 and S1).
4) The "gate seal detection process" of this cycle is completed.

Hereinafter, the PMC CPU 114 is the NC C
Until the drive control of the screw 1 in the injection pressure holding process is started by the processing of the PU 112 in the same manner as in the conventional case, only the processing of step S1, step S13, and step S14 in the "gate seal detection processing" for each predetermined cycle is performed. This is repeatedly executed, and the start of the injection pressure holding step is awaited.

When the start of the injection pressure holding process is detected in the determination process of step S1 in the "gate seal detection process", the PMC CPU 114 determines whether or not the display completion flag F is set ( Step S
2) Since the flag F is in the reset state immediately after the start of the injection pressure-holding process [see the processing of step S14], the value of the processing cycle integration counter t having an initial value 0 [see the processing of step S13] is set to Increment by 1 to start measuring the elapsed time from the start of injection (step S3), and set the molding condition in the setting memory unit of the shared RAM 105 corresponding to the current value Va of the screw forward speed and the current injection stage or current holding stage. The holding pressure setting value Ph stored as is read and temporarily stored (step S4). Note that there is no substantial difference even if the actual resin pressure at the present time is read from the latest address of the RAM 108 instead of the set value Ph of the holding pressure stored as the molding condition.

Although the injection molding machine of the embodiment is not individually provided with a special means for detecting the forward speed of the screw 1, the RA in the process of step S4 described above.
The screw position stored in the latest address of M109 and the screw position stored in the address immediately before that are read to obtain the screw position difference, and this difference is divided by the address command cycle in the address generator 118 to determine the screw forward speed. The current value Va of is calculated. The rotation speed of the servo motor 2 detected by the speed loop of the digital servo circuit 103 is written into the shared RAM 105 at predetermined intervals by the processing of the NC CPU 112, or the F / V converter or the tacho generator of the hardware servo circuit 103 is written. A / D conversion of the output from the shared RAM 105
Shared RAM
It is also possible to read the current value Va of the screw forward speed based on the rotation speed of the servo motor 2 stored in 105.

In the execution stage of each injection stage in which resin is filled, there is no set holding pressure in a narrow sense, but at this stage, the value of the torque limit corresponding to the maximum allowable injection pressure is the set holding pressure. Will be read as. In addition, the expression of the current injection stage or the current holding stage is
This is because the injection speed and the holding pressure in the injection pressure holding process may be set in multiple stages.
It may be set in stages and is not a substantial limiting factor.

The PMC CPU 114, which has read the current value Va of the screw advancing speed and the set value Ph of the holding pressure as the molding condition, then initializes the value of the set value search index i as a pre-process for file search. (Step S
5) Further, the value of the index i is incremented by 1 (step S6), and it is determined whether or not the value of the index i reaches the number n of set values stored in the set value storage file (step S7).

If the value of the set value search index i has not reached the number of stored n, the PMC CPU 114 accesses the i-th address of the set value storage file of the shared RAM 105 based on the current value of the index i, and saves the setting. The lower limit Phi-1 and the upper limit Phi of the allowable pressure pressure range are read, and the set value Ph of the holding pressure stored as the molding condition corresponding to the current injection stage or the current holding stage is stored in the i-th set value storage file. It is determined whether or not it is within the range of the lower limit Phi-1 and the upper limit Phi of the allowable width of the set holding pressure stored in the address (steps S8 and S9).

At this time, step S8 and step S
If both the determination results of 9 are true, the set value Ph of the holding pressure stored as the molding condition corresponding to the current injection stage or the current holding stage is the setting hold stored in the i-th address of the set value storage file. Pressure Lower limit Phi-1 and upper limit Phi of allowable width of pressure
Is included in the range of step S
8 or step S9, if either of the determination results is false, the set value Ph of the holding pressure stored as the molding condition corresponding to the current injection stage or the current holding stage is the i-th address of the set value storage file. It means that it is not included in the range of the allowable width of the set holding pressure stored in (1).

Therefore, step S8 or step S
If either of the discrimination results of 9 is false, PM
The C CPU 114 returns to the process of step S6 again, increments the value of the set value search index i by 1, and the determination results of step S8 and step S9 are both true and correspond to the current injection stage or the current holding stage. Holding pressure setting value P
Until the address i of the setting value storage file having the allowable width including h is detected, or until the determination result of step S7 becomes true and there is no data to be searched, the same operation as described above is performed. The loop of the search process of steps S6 to 9 is repeatedly executed. Note that step S7
If the determination result of is true, it means that the screw forward speed for detecting the gate seal completion is not set for the holding pressure setting value of this injection stage or the holding stage, The PMC CPU 114 completes the "gate seal detection process" of the processing cycle as it is.

On the other hand, the determination results of step S8 and step S9 both become true, and the address i of the set value storage file having the allowable width corresponding to the set holding pressure Ph of the current injection stage or the current holding stage is detected. CP for PMC
U114 further reads the set value Vmi of the screw forward speed, which is the criterion for determining the gate seal completion, from the i-th address of the set value storage file corresponding to this allowable width, and the screw forward speed Va at the present time is below the set value Vmi. It will be determined whether or not (step S1)
0).

As described above, since the large resistance does not act on the screw 1 immediately after the start of injection and the value of the forward speed Va of the screw 1 is very large, the screw forward speed Va is the criterion for determining the completion of the gate seal. Does not fall below the set value Vmi of the screw advancing speed, and the determination result of step S10 becomes false, and the PMC CPU 11
4 finishes the "gate seal detection process" of the processing cycle as it is.

Hereinafter, the PMC CPU 114 is the NC C
While the PU 112 performs the screw pressure control in the injection pressure-holding process, similarly to the above, the processes of steps S1 to S10 are repeatedly executed in the “gate seal detection process” at predetermined intervals, but the resin is not discharged from the start of injection. Since a large resistance does not act on the screw 1 until the filling is completed, the current value Va of the screw advancing speed does not fall below the set value Vmi of the screw advancing speed that is the criterion for determining the completion of the gate seal ( Even if the result of the determination in step S10 is false), and even when the resin filling is completed and the initial pressure-holding operation is started, the molten resin left as a cushion amount at the tip of the cylinder, the runner of the injection molding die, and the metal mold. Since the screw 1 can continue to move forward at a constant speed or higher while compressing the molten resin in the mold cavity, Although the advancing speed is slower, again, the determination result of step S10 is false.

That is, the reaction force of the resin acting on the screw 1 when the filling is completed and the initial pressure-holding operation is started,
The total volume of molten resin that can be compressed immediately after the completion of filling is set under standard measuring conditions to seal the nozzle of the injection cylinder, and it corresponds to the set holding pressure that is the molding condition of the current holding stage. Standard holding pressure (Phi-1 + Phi)
Since it is almost equal to the reaction force when the screw is driven at / 2, the current value Va of the screw forward speed is equal to the holding pressure (Ph
It does not fall below the set value Vmi of the screw advancing speed for completion of gate seal, which is set and stored corresponding to i-1 + Phi) / 2. Strictly speaking, the screw forward speed when simply sealing the nozzle and applying the holding pressure and the screw forward speed when filling the molten resin in the injection mold and applying the holding pressure Although there is a difference, if the value of the set value Vmi is determined in advance in consideration of the negative error width, no problem will occur.

Then, while the PMC CPU 114 repeatedly executes the processing of steps S1 to S10 in the "gate seal detection processing" for each predetermined cycle, the resin filled in the gate portion in the injection molding die is solidified. Then, when the gate sealing is completed, the resin in this portion completely closes the gate and isolates the resin in the mold cavity, so that the resin that can be compressed by the screw 1 is left as a cushion amount at the tip of the cylinder. Only the molten resin and the semi-solidified resin filled in the runner of the injection molding die are reduced, and the volume of the resin that can be compressed is reduced compared to the stage before the completion of the gate sealing, and the screw 1 that compresses the resin and advances it 1
Also, the forward speed Va of (1) becomes significantly slower than the state before the completion of the gate seal, and falls below the set value Vmi of the screw forward speed that is the criterion for determining the completion of the gate seal.

The PMC CPU 114, which repeatedly executes the processing of steps S1 to S10 in the "gate seal detection processing" for each predetermined cycle, determines the forward speed V of the screw 1.
The fact that a has fallen below the set value Vmi is detected by the discrimination processing in step S10, this is detected as the completion of the gate seal, and then the display completion flag F is set to complete the gate seal in the injection pressure holding process. Is stored (step S11), and the value of the processing cycle integration counter t, which has been incremented by one for each processing cycle of the “gate seal detection processing” after the start of the injection pressure holding step, is set to “gate seal detection processing”. Multiply the processing period τ to obtain the gate sealing time “t · τ” of the injection pressure holding step,
Gate seal time “t · τ” value is CRT / MDI11
Display on the display screen of 9 to inform the molding operator,
A pressure holding completion signal is output (step S12), and the "gate seal detection process" of this cycle ends.

Hereinafter, the PMC CPU 114 repeatedly executes the "gate seal detection process" for each predetermined cycle, but when the completion of the gate seal in the one injection pressure-holding process is detected, the display completion flag F has already been reached. Is set, the processes from step S3 to step S12 are not executed in the "gate seal detection process" on and after the next cycle.

When the drive control of the screw 1 for the one injection pressure holding process based on the processing of the NC CPU 112 is completed, the injection pressure holding process execution flag is reset and the determination in step S1 in the "gate seal detection process" is performed. The result is false, and the PMC CPU 114 initializes the processing cycle integration counter t and the display completion flag F (steps S13 and S14), and then repeats only the processing of steps S13 and S14 in the "gate seal detection processing". It executes and waits until the injection pressure holding step of the next cycle is started.

In the process of step S12 described above, CR
The value of the gate seal time “t · τ” of the one injection pressure holding step displayed on the display screen of the T / MDI 119 is
It is held on the display screen of the CRT / MDI 119 as it is until the new gate seal time “t · τ” is updated and displayed in the “gate seal detection process” performed in the injection pressure maintaining process of the next cycle.

The PMC CPU 114 repeatedly executes the series of processes in the above-mentioned "gate seal detection process" for each injection pressure holding process by the same algorithm to detect the gate seal timing for each injection pressure holding process. The gate seal time “t · τ” is updated and displayed on the display screen of the CRT / MDI 119, and the pressure holding completion signal is output in synchronization with the detection of the gate seal timing.

Since it is possible to know the gate seal time "tτ" in the one injection pressure holding step performed immediately before by simply referring to the display screen of the CRT / MDI 119,
Based on this value, the operator can easily and accurately set molding conditions such as holding pressure holding time and cooling time, and speed up the injection molding cycle by eliminating unnecessary holding time and cooling time. can do. In addition, the operator himself / herself refers to the gate seal time “t · τ” to reset the pressure holding time and the cooling time, and instead of using the pressure holding completion signal output in step S12, based on the control of the NC CPU 112. It is also possible to automatically start the metering operation of the next step and shorten the pressure holding time (when the cooling time may be short).

As one embodiment, the set value of the screw advancing speed which should be regarded as the completion of the gate seal is stored in correspondence with the holding pressure which has the greatest effect on the advancing speed of the screw 1 in the pressure holding process. Although an example has been described (see FIG. 3), other molding conditions that affect the advancing speed of the screw 1 in the pressure holding process, for example, the screw advancing speed that should be regarded as the completion of gate sealing depending on the type of resin used. The set value may be stored, and further, a plurality of molding conditions that affect the advancing speed of the screw 1 in the pressure holding process are combined, and the screw advancing that should be regarded as gate seal completion corresponding to each of them is combined. You may make it memorize | store the setting value of speed.

When a set value of the screw advancing speed that should be regarded as the completion of the gate seal is determined by combining a plurality of molding conditions, for example, the holding pressure and the type of resin used are combined to determine the screw advancing speed. In the case of determining the set value, only the holding pressure that greatly affects the advancing speed of the screw 1 in the pressure holding process is registered in the set value storage file, and the resin used at the stage of performing the molding operation is further registered. By inputting the type from the CRT / MDI 119 and storing the correction coefficient corresponding to the resin used in the control device, every time the set value of the forward speed that should be regarded as the completion of the gate seal is selected, the correction coefficient is added to the set value. It is also possible to multiply by and perform the determination processing of step S8 and step S9. Further, in order to detect the gate seal more easily, the gate seal completion should be detected only when the current value of the screw speed becomes less than or equal to the set screw forward speed regardless of the holding pressure. May be.

[0050]

The gate seal completion detecting method of the present invention comprises:
The value of the screw forward speed that should be regarded as the completion of the gate seal is stored in advance in the control device of the injection molding machine as a set value, and the magnitude relationship between the screw forward speed and the set value in the injection pressure holding step is sequentially compared. However, based on the determination result, the size of the resin that can be compressed by the screw, that is, whether the resin in the mold cavity and the resin in the runner and the injection cylinder are integrally compressed, or Since it is determined whether or not only the resin in the runner and the injection cylinder is compressed, it is possible to accurately detect whether or not the gate separating the resin and the runner in the mold cavity is sealed. be able to.

Further, a plurality of set values of the screw advancing speed which should be regarded as the completion of the gate seal are set and stored according to the molding conditions which affect the screw advancing speed, for example, the difference in the holding pressure and the like. Since the gate seal determination operation is performed after selecting the set value that corresponds to the molding conditions, it is possible to accurately detect the gate seal timing even if the molding conditions are changed. it can.

Further, since the time required from the start of injection to the completion of the gate seal is displayed on the display, the molding conditions such as holding time of pressure holding pressure and cooling time can be easily set based on the time required for the gate seal. It can be set appropriately, and unnecessary injection pressure holding time and cooling time can be omitted to speed up the injection molding cycle. Moreover, since the pressure holding completion signal is automatically output when the gate sealing is completed, it is possible to immediately start the next process related to the injection molding operation at the stage when the gate sealing is detected.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of an injection molding machine of an embodiment to which a gate seal detecting method of the present invention is applied.

FIG. 2 is a flowchart showing an outline of a “gate seal detection process” by the control device of the injection molding machine of the embodiment.

FIG. 3 is a conceptual diagram showing an outline of a set value storage file provided in the control device.

[Explanation of symbols]

1 Screw 2 Injection Servo Motor 100 Control Device 102 Counter 105 Shared RAM 109 RAM 112 Microprocessor for Numerical Control (CP for NC)
U) 114 Microprocessor for programmable machine controller (CPU for PMC) 117 ROM 119 Manual data input device equipped with CRT to be a display

Claims (6)

[Claims] 1. The value of the screw advancing speed that should be regarded as the completion of the gate seal is stored in advance in the controller of the injection molding machine as a set value, and the screw advancing speed in the injection pressure-holding step is sequentially detected to obtain the value. A method for detecting completion of gate seal in an injection molding machine, which compares with a set value and detects when the screw advancing speed falls below the set value as completion of gate seal. 2. A plurality of screw forward speed values that should be regarded as completion of gate sealing are stored in advance as a set value in a control device of an injection molding machine in association with molding conditions that affect the screw forward speed. Select the set value corresponding to the set molding conditions, sequentially detect the screw forward speed in the injection pressure holding step and compare with the set value,
A method for detecting completion of gate seal in an injection molding machine, wherein the time when the current value of the screw advancing speed falls below the set value is detected as completion of gate seal. 3. The method for detecting completion of gate seal in an injection molding machine according to claim 1, wherein the set value is determined at least by a holding pressure. 4. The method for detecting completion of a gate seal in an injection molding machine according to claim 1, wherein the set value is determined by a holding pressure and a type of resin used. 5. The method according to claim 1, wherein the time from the start of injection to the completion of the gate seal is measured and displayed on the display of the control device.
A method for detecting completion of a gate seal in the described injection molding machine. 6. A method of detecting completion of gate seal in an injection molding machine according to claim 1, claim 2, claim 3, claim 4 or claim 5, wherein a pressure holding completion signal is output when the gate seal is completed. ..