JP4278592B2 - Mold protection method for injection molding machine - Google Patents

Description

  The present invention relates to a mold protection method for an injection molding machine, and in particular, measures a mold temperature at the time of molding, corrects it to an appropriate mold protection pressure setting value corresponding to the mold temperature, and performs automatic operation. The present invention relates to a new improvement for enabling smooth automatic operation while avoiding malfunction of a mold protection function.

Conventionally, as a mold protection method of this type of injection molding machine, there is a configuration proposed in Patent Documents 1, 2, 3 and the like described later, and the mold clamping device is not shown, but is attached to a stationary platen. A linear reciprocating motion for opening and closing the movable mold held by the movable plate is performed on the held fixed mold, and the mold is clamped in the mold closed state.
When a foreign object is sandwiched between the movable mold and the fixed mold during the mold closing operation of the mold clamping device, if the mold closing is forced as it is, the mold is damaged and a normal product cannot be molded. Therefore, a mold protection method for preventing the mold from being damaged at such an abnormal time is applied to the mold clamping device.

  FIG. 4 is a flowchart showing the processing operation of the mold protection method of the conventional electric injection molding machine, and FIG. 3 is the relationship between the elapsed time and the load torque of the servo motor in the mold closing operation of the conventional electric injection molding machine. FIG.

Next, the mold protection processing operation of the conventional electric injection molding machine will be described based on the diagram of FIG. 3 and the flowchart of FIG.
First, when the movable mold performs the mold closing operation and reaches the mold protection start position a, the mold protection processing operation is started. First, the drive torque of the supporter that drives the mold clamping device is limited to the mold protection torque TR ₀ and the mold closing operation is continued (first step S ₁ ). Next, it is determined whether or not the mold has reached the mold touch position b (second step S ₂ ). If it has reached, the mold is closed, that is, the mold touch is completed, and the mold protection processing operation is terminated, and the process proceeds to the mold clamping operation. If not reached, it is next determined whether or not the drive torque has increased to the mold protection torque TR ₀ (third step S ₃ ). If you do not have to rise back to the second step S _2. If it has risen, then the timer starts counting (fourth step S ₄ at position C in FIG. 3). Next, it is determined whether or not the timer timing has passed the mold protection time T _1. Determination is made (fifth step S ₅ at positions c to d in FIG. 3). If it is not passed back to the second step S _2. If it has elapsed, an alarm is then issued (sixth step S ₆ at position d in FIG. 3).

Japanese Patent No. 3080617 JP-A-9-267370 JP 2002-36327 A

Since the conventional mold protection method for an electric injection molding machine is configured as described above, the following problems exist.
That is, when the molding conditions change, such as changing the mold temperature and pressure conditions during molding or changing the mold, it is necessary to change the mold protection set value at the same time. In particular, when molding starts and the mold temperature rises, the mold itself expands due to heat, and the fitting of the guide pin sliding part of the fixed mold is slightly misaligned, resulting in a slight load for closing the mold. A phenomenon occurs in which the torque increases. Normally, mold protection is set before molding starts. Depending on the mold, the mold protection pressure must be set again due to the rise in mold temperature after molding starts. There was a problem that the protective function worked and the mold closing operation was stopped.

  The mold protection method for an injection molding machine according to the present invention uses a clamping device that moves a movable mold relative to a fixed mold of an injection molding machine, measures the temperature of the mold during molding, The mold protection pressure value stored in the mold protection pressure table in advance corresponding to the mold temperature is compared with a preset mold protection pressure set value, and the mold protection pressure value is the mold protection pressure. When the set value is larger than the set value, the mold protection pressure set value is corrected, and the protection pressure correction value used for the correction is a mold opening / closing servo motor for each temperature range based on the temperature range of the mold temperature. And the protective pressure correction value is a method set based on at least the capacity, peak torque, and model of the mold opening / closing servo motor, Also, the temperature of the mold temperature Is changeable and the method, also, the mold clamping device is a method in which a toggle.

Since the mold protection method for an injection molding machine according to the present invention is configured as described above, the following effects can be obtained.
In other words, after molding starts, an appropriate mold protection pressure corresponding to the mold temperature is detected and compared with the mold protection pressure setting value set by the operator. Since the function to change the mold protection pressure setting value is provided in the automatic operation, after the automatic operation is started, the mold protection function is activated even though it is normal, and the mold closing operation is stopped. It is not necessary for the operator to correct the mold protection setting again, and a series of operations from setup to automatic operation can be performed smoothly, so that productivity can be improved. In addition, since the initial setting value of the mold protection pressure is provided in the mold protection pressure table, there is an effect of preventing an operator's erroneous input.

  The present invention provides a mold protection pressure table storing an appropriate mold protection pressure value corresponding to the mold temperature at the time of molding in the controller, and measures the mold temperature for each molding shot. The objective is to compare the protection pressure value with the mold protection pressure value preset by the operator, automatically correct the mold protection pressure setting value using the protection pressure correction value, and perform smooth automatic operation. .

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a mold protecting method for an injection molding machine according to the present invention will be described with reference to the drawings.
FIG. 1 shows a mold clamping device 10 of an injection molding machine to which the mold protection method for an injection molding machine according to the present invention is applied. FIG. 2 shows a mold preset in the controller 5 by an operator of the injection molding machine. 1 is a mold protection pressure table 11 provided in the controller 5 of FIG. 1 for automatically correcting the mold protection pressure set value BR, and the motor torque of the mold opening / closing servo motor 6 of FIG. organize mold protection pressure value of the temperature range apart from the most appropriate value based on the temperature range of the mold AR ₁ to Ar ₄ as a database, further the switchgear servo for correcting each of said mold protection pressure setpoint BR Protection pressure correction values TR _{1 to} TR ₄ set as torque values of the motor 6 are set for each temperature range.

Here, the mold protection pressure at the time of molding is controlled by the mold opening / closing servo motor 6. Therefore, the protection pressure correction values TR _{1 to} TR ₄ are managed as torque values of the servo motor 6. In addition, since the capacity of the servo motor 6 and the motor torque (peak torque) required to close the mold are different depending on each model, the value in the mold protection pressure table 11 varies depending on each model. Further, when the mold temperature is 0 to 40 ° C., it is considered that the influence of expansion due to heat is very small. Therefore, the table data during this period is the initial set value of the mold protection pressure set value BR. The protective pressure correction values TR _{1 to} TR ₄ can be set based on any or all of the capacity, peak torque, and model of the servo motor 6.

FIG. 1 shows a block diagram of a mold clamping device 10 in a case where the mold protection method of the present invention is applied to an injection molding machine equipped with a toggle type mold clamping mechanism of an electric injection molding machine. In FIG. 1, 1 indicates a fixed mold attached to the fixed plate 3 on the base 1A, and 2 indicates a movable mold attached to the movable plate 4 on the base 1A. Temperature sensors 1a and 2a for measuring the mold temperature are attached to the fixed mold 1 and the movable mold 2, respectively. 5 is a controller of the injection molding machine, and a mold protection pressure indicating a relationship with appropriate mold protection pressure values AR _{1 to} AR ₄ corresponding to a mold temperature in a temperature range based on the temperature range of the molds 1 and 2. A detector (not shown) for detecting the temperature of the mold 1 and 2 measured by the table 11 and the temperature sensors 1a and 2a, the detected mold temperature and the protection pressure correction in the mold protection pressure table 11 A comparator (not shown) for comparing and verifying the values TR _{1 to} TR ₄ is provided in the controller 5.

Next, the operation of the controller 5 at the time of correcting the mold protection pressure in the above-described configuration will be described. Measurement is performed for each molding shot, and the measured temperature is read by the detector. An appropriate mold protection pressure value AR _{1 to} AR ₄ read from the mold protection pressure table 11 corresponding to the measured mold temperature is compared with a mold protection pressure set value BR preset by an operator by a comparator. If correction is required, a command is issued to the mold opening / closing servomotor 6 so that the preset protective pressure correction values TR _{1 to} TR ₄ in the table 11 remain pressure values. Here, when correction is necessary, the data of the mold protection pressure values AR _{1 to} AR ₄ corresponding to the mold temperature measured by the temperature sensors 1 a and 2 a is based on the mold protection pressure setting value preset by the operator. Is larger, that is, when the motor torque of the protection pressure set value BR or more is required when the mold is closed. Conversely, when the table data is smaller than the operator set value, the automatic correction does not work. .

In other words, the mold temperature starts to rise when the operator sets the molding conditions, but it takes a little time to raise the temperature to the preset temperature, but the mold temperature fluctuates slightly even after the temperature is raised to the preset temperature. To do. Therefore, the temperature range of the mold and it to the appropriate mold protection pressure value AR ₁ to Ar ₄ and the protective pressure correction value TR ₁ to Tr ₄ and mold protection pressure table 11 and the mold protect pressure setpoint showing the relationship BR is provided in advance in the controller 5 of the molding machine. The mold protection pressure table shown in FIG. 2 will be described. First, the mold protection pressure at the time of molding is controlled by the mold opening / closing servo motor 6. Therefore, the correction values TR _{1 to} TR ₄ are managed as torque values of the servo motor 6. As mentioned above, the motor torque required for mold closing varies slightly depending on the mold temperature change. Therefore, the motor torque required for mold closing is organized in advance as a database for each mold temperature range, and this is used as the mold protection pressure. Table 11 is assumed. Since the capacity of the mold opening / closing servo motor, its peak torque, and the motor torque required for mold closing differ depending on the model, the correction value (motor torque value) in the mold protection pressure table 11 differs depending on the model.

Accordingly, when automatic molding is started after the molding conditions are set, an appropriate mold protection pressure value AR ₁ corresponding to the mold temperature measured for each molding shot based on the mold protection pressure table 11 in the controller 5. AR ₄ is selected and compared with the mold protection pressure set value BR preset by the operator. When the mold protection pressure values AR _{1 to} AR ₄ in the table 11 corresponding to the measured mold temperature are larger than the mold protection pressure setting value BR of the worker, that is, when the mold is closed, the mold protection pressure value is equal to or higher than the mold protection setting pressure. When the motor torque is required, the controller 5 changes the set value based on the table data. Conversely, if the table data is smaller than the operator's set value, the automatic correction does not work. However, when the mold temperature is between 0 and 40 ° C., it is considered that the influence of expansion due to heat is considered to be extremely small. Therefore, the table data during this period is provided for the purpose of correcting erroneous input by the operator, That is, it is set as an initial set value. In addition, the structure of the molds 1 and 2 is various, and this function of automatic correction is not necessary for molds that are less affected by expansion of the mold due to heat, so automatic correction of mold protection in each mold. Whether or not a function is required is left to the operator, and automatic correction can be switched between valid and invalid on the user setting screen.
Therefore, after automatic molding is started, it is necessary for the operator to correct the mold protection setting again by the mold protection function acting even though it is normal and the mold closing operation being stopped. Therefore, a series of operations from the setup to the automatic operation can be performed smoothly, and the work is not interrupted, so that productivity can be improved.

  The present invention is not limited to an injection molding machine but can be applied to a mold of an extrusion molding machine.

It is a block diagram which shows the mold clamping apparatus to which the metal mold | die protection method of the injection molding machine by this invention is applied. It is a block diagram of the metal mold | die protection pressure table built in the controller of FIG. It is a diagram which shows the relationship between the time passage in the mold closing operation of the conventional electric injection molding machine and the load torque of the servo motor. It is a flowchart which shows the processing operation | movement of the metal mold | die protection method of the conventional electric injection molding machine.

Explanation of symbols

1 fixed die 2 the movable mold 5 controller 6 type closing servo motor 10 mold clamping device 11 mold protection pressure table AR ₁ to Ar ₄ mold protection pressure value TR ₁ to Tr ₄ protective pressure correction value BR Mold protection pressure setting value

Claims (5)

Using the mold clamping device (10) that moves the movable mold (2) relative to the fixed mold (1) of the injection molding machine, the temperature of the mold (1, 2) is measured during molding, and the mold Corresponding to the mold temperature of (1,2), the mold protection pressure value (AR _{1 to} AR ₄ ) stored in the mold protection pressure table (11) in advance and the preset mold protection pressure set value ( BR) and comparing, the mold protection pressure value (AR ₁ ~AR ₄₎ is for large than the die protective pressure setpoint (BR), to correct the mold protection pressure set value (BR) A mold protection method for an injection molding machine. The protective pressure correction values (TR _{1 to} TR ₄ ) used for the correction are set as torque values of the mold opening / closing servo motor (6) for each temperature range based on the temperature range of the mold temperature. Item 2. A mold protection method for an injection molding machine according to Item 1. The protective pressure correction value (TR _{1 to} TR ₄ ) is set based on at least the capacity, peak torque, and model of the mold opening / closing servo motor (6). Or the mold protection method of the injection molding machine of 2. 4. The mold protection method for an injection molding machine according to claim 2, wherein the temperature range of the mold temperature is changeable.   5. The mold protection method for an injection molding machine according to claim 1, wherein the mold clamping device (10) is a toggle type.

Images