JP3891325B2 - Mold opening and closing device of molding machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mold opening and closing device for a molding machine such as an injection molding machine or a die casting machine.
[0002]
[Prior art]
In molding machines such as injection molding machines, electric machines have recently become widespread. By the way, in an injection molding machine, during the mold opening process, for example, if a slide core galling or an asymmetric force acts on the pulling link occurs in the mold mechanism, the mold is opened with excessive force. If the process is continued, the mold mechanism may be damaged. Therefore, in order to prevent damage to the mold mechanism (to protect the mold cannism), a configuration is often adopted in which the output torque of the electric servo motor is limited during the mold opening process. That is, during the mold opening process, a so-called torque limiter is applied to the electric servo motor, thereby preventing an excessive force from acting on the mold opening / closing mechanism and preventing the mold mechanism from being damaged. .
[0003]
[Problems to be solved by the invention]
As mentioned above, applying a torque limiter to the electric servo motor, which is the mold opening / closing drive source during the mold opening process, can prevent the mold mechanism from being damaged, but the acceleration / deceleration performance of the mold opening process will be reduced and may stop in some cases. Position overrun may occur. In order to prevent this overrun, measures such as increasing the deceleration curve are taken, but the acceleration / deceleration performance of the mold opening stroke is poor and the deceleration curve is increased, so the time for the mold opening stroke Therefore, there is a problem that it is not suitable for high cycle molding.
[0004]
The present invention has been made in view of the above points. The object of the present invention is to prevent damage to the mold mechanism in the mold opening process and to perform high cycle molding without impairing the acceleration / deceleration performance of the mold opening process. Is to provide a simple molding machine.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a mold opening / closing device of a molding machine according to the present invention includes a load detection means for detecting a load of a mold opening / closing mechanism at least in a mold opening stroke, and a mold opening / closing in a mold opening stroke detected by the load detection means. and comparing the tolerance mechanisms measured load with a preset load, if the actual load is out of the allowable range, and a control means for stopping the operation of the mold opening and closing drive source, comprising, mentioned above The allowable load range is set to a positive value range from the start of mold opening to the end of mold opening, and to a negative value range at the end of mold opening.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a main configuration of an injection molding machine according to an embodiment of the present invention.
[0007]
In FIG. 1, reference numeral 1 denotes a fixed die plate on which a fixed die 2 is mounted, 3 denotes a movable die plate on which a movable die 4 is mounted, and moves forward and backward relative to the fixed die plate 1, 5 denotes a movable die plate 3. , A tie bar for guiding the mold 6, a servomotor (electric servomotor) as a mold opening / closing drive source, 7 a rotation for converting the rotation of the servomotor 6 into a linear motion → a ball screw mechanism that is a linear motion mechanism, and 8 a ball screw mechanism 7 is a toggle link mechanism that receives the linear motion 7 and moves the movable die plate 3 forward or backward. A servo amplifier 9 controls driving of the servomotor 6. A drive current of the servomotor 6 is measured. The measurement result is used as data corresponding to a torque value (that is, data corresponding to a load of the mold opening / closing mechanism). A current detector 11 to be sent to the machine controller, which will be described later, is an encoder that detects the rotation of the servo motor 6 and sends the measurement result to the machine controller to be described later.
[0008]
Reference numeral 20 denotes a machine controller embodied by a function of a microcomputer or the like. Actually, the machine controller 20 controls the entire machine (injection molding machine), and includes an MPU, ROM, RAM, various I / Os. Although it is configured with an O interface or the like, only the part related to the display control unit and the mold opening / closing control system is shown here. Reference numeral 30 denotes a keyboard device for performing various input settings and instruction inputs to the machine controller 20, and reference numeral 40 denotes a display device such as a color LCD that displays various screens under the control of the machine controller 20.
[0009]
In the machine controller 20, 21 is a mold opening condition storage unit, 22 is a mold opening operation actual value storage unit, 23 is a mold opening operation control unit, 24 is an allowable torque range storage unit, and 25 is a torque comparison determination unit. , 26 is a display control unit that generates display screen data and outputs it to the display device 40.
[0010]
In the mold opening condition storage unit 21, as the operating condition setting data in the mold opening process, for example, the relationship between the position (stroke) of the crosshead of the toggle link mechanism 8 and the speed (or the position and speed of the movable die plate 3). Etc.) are stored so as to be rewritable. Further, the actual measured value of the mold opening operation is stored in the mold opening operation actual value storage unit 22 and stored temporarily in real time. The actual operation value taken into the mold opening actual operation value storage unit 22 is, for example, a torque value obtained by appropriately converting the actual current value output from the current detector 10 and the rotation amount data output from the encoder 11. Is a speed value calculated based on the stroke value (or the stroke value of the movable die plate 3) which is the position data of the cross head of the toggle link mechanism 8 obtained by appropriately converting and calculating the position (stroke) data and the clock. .
[0011]
The mold opening operation control unit 23 moves the servo amplifier 9 to the position axis while referring to the actual measurement data captured in the mold opening operation actual value storage unit 22 in real time so as to follow the operation condition setting data of the mold opening condition storage unit 21. For example, drive control is performed by speed feedback control.
[0012]
The allowable torque range storage unit 24 includes, for example, a position axis indicating the stroke value of the cross head of the toggle link mechanism 8 in the mold opening stroke (or a position axis indicating the stroke value of the movable die plate 3 in the mold opening stroke). The allowable torque range data of the servo motor 6 set in the above manner is stored so that it can be rewritten.
[0013]
The torque comparison / determination unit 25 constantly compares the allowable torque range data set in the allowable torque range storage unit 24 and the actually measured torque value at the current stroke position during the mold opening stroke period, and the actually measured torque value is within the allowable torque range. If it is off, a stop control command is sent to the mold opening operation control unit 23. Then, when a stop control command arrives from the torque comparison / determination unit 25, the mold opening operation control unit 23 immediately stops the servo motor 6 immediately and interrupts the mold opening process.
[0014]
In the above configuration, when the mold opening start timing is reached, the servo motor 6 starts to be driven to rotate via the servo amplifier 9 by the drive signal from the mold opening operation control unit 23. The rotation of the servo motor 6 is converted into a linear motion by the ball screw mechanism 7, and this linear motion is transmitted to the cross head of the toggle link mechanism 8, and the movable die in the mold clamping state position is transmitted via the toggle link mechanism 8. The plate 3 starts to be driven backward. The mold opening process is performed by, for example, speed feedback control, and the mold opening operation control unit 23 performs drive control of the servo amplifier 9 so that the actual speed coming from the actual mold opening operation value storage unit 22 matches the set speed. Do. During execution of the mold opening process, the torque comparison / determination unit 25 compares the allowable torque range data set in the allowable torque range storage unit 24 with the actual torque value at the current position, and the actual torque value is the allowable torque. If the measured torque value is within the allowable torque range until the end of the mold opening stroke, the mold opening stroke is normally executed and the movable die plate is monitored. 3 will be in the state which moved to the mold opening end position. On the other hand, if the measured torque value is out of the allowable torque range during the mold opening process, the torque comparison / determination unit 25 sends a stop control command to the mold opening operation control unit 23, whereby the mold opening operation control unit. 23 immediately stops the rotation of the servo motor 6 and urgently interrupts the mold opening process.
[0015]
FIG. 2 is a diagram showing the relationship between the allowable torque range set in the allowable torque range storage unit 24 and the actually measured torque of the mold opening stroke. The vertical axis in FIG. 2 represents the torque value, and the horizontal axis represents the stroke value. In FIG. 2, 51 is an allowable torque range corresponding to the stroke value of the cross head of the toggle link mechanism 8 in the mold opening stroke, and 52 is an actually measured torque in the mold opening stroke.
[0016]
FIG. 2A shows a case where the mold opening is normally performed. In this case, the cross head (or the movable die plate 3) of the toggle link mechanism 8 is moved from the mold opening start position to the mold opening position. The measured torque 52 remains within the allowable torque range 51 until reaching the opening end position. FIG. 2B shows a case where the actually measured torque 52 deviates from the allowable torque range 51 during the mold opening process. In such a case, immediately after the actually measured torque 52 deviates from the allowable torque range 51, FIG. The servo motor 6 is urgently stopped. FIG. 2B shows a case where the actually measured torque 52 exceeds the upper limit value of the allowable torque range 51 (that is, when the load exceeds the set value). Even when the value falls below the lower limit value of the torque range 51, the servo motor 6 is urgently stopped assuming that the load has become smaller than the normal state and some abnormality has occurred.
[0017]
Here, the setting range of the allowable torque range 51 is arbitrary, and the setting range can be varied for each position. The allowable torque range 51 is set by causing the display device 40 to display a mold opening stroke allowable torque range setting mode screen and interactively interacting with this screen, for example, an average of actually measured torques during a normal mold opening stroke. In the state where the values are displayed as shown in FIG. 2, the allowable torque range is input by drawing, or the upper and lower limits of each value are input numerically.
[0018]
According to the present embodiment as described above, the mold mechanism can be reliably prevented from being damaged during the mold opening process. In addition, unlike the conventional case, no torque limiter is applied to limit the output torque of the servo motor, so the acceleration / deceleration performance of the mold opening process is not impaired and high cycle molding can be easily performed. It becomes.
[0019]
In the above embodiment, an example in which the toggle link mechanism 8 is used in the mold opening / closing mechanism has been shown. However, a direct pressure type mold opening / closing apparatus in which the movable die plate 3 is directly driven by the ball screw mechanism 7 is also used. It goes without saying that the present invention is applicable. In some cases, the present invention can be applied to a configuration in which the mold opening / closing drive source is a hydraulic cylinder. The allowable torque range storage unit 24 may store the allowable torque range data of the servo motor 6 set along the time axis from the mold opening start timing in the mold opening process. .
[0020]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a molding machine capable of preventing high-speed molding without impairing the acceleration / deceleration performance of the mold opening process while preventing damage to the mold mechanism in the mold opening process.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a main configuration of an injection molding machine according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a relationship between an allowable torque range of a mold opening stroke and measured torque in an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fixed die plate 2 Fixed side metal mold 3 Movable die plate 4 Movable side metal mold 5 Tie bar 6 Servo motor 7 Ball screw mechanism 8 Toggle link mechanism 9 Servo amplifier 10 Current detector 11 Encoder 20 Machine controller 21 Mold opening condition storage part 22 type Opening operation actual value storage unit 23 Mold opening operation control unit 24 Allowable torque range storage unit 25 Torque comparison determination unit 26 Display control unit 30 Keyboard device 40 Display device

Claims (4)

A mold closing operation is performed by moving a movable die plate mounted with a movable mold toward a fixed die plate mounted with a fixed mold by a mold opening / closing drive source, and the movable die plate is moved from the fixed die plate. In a molding machine that performs a mold opening operation by retreating in a separating direction,
The load detection means for detecting the load of the mold opening / closing mechanism in at least the mold opening stroke, and the measured load of the mold opening / closing mechanism in the mold opening stroke detected by the load detection means are compared with a preset allowable load range to measure the load. A control means for stopping the operation of the mold opening / closing drive source when the load is outside the allowable range;
Equipped ,
The mold opening / closing device of the molding machine is characterized in that the allowable load range is set to a positive value range from the start of mold opening to the end of mold opening, and to a negative value range at the end of mold opening. In claim 1,
The mold opening / closing apparatus of a molding machine, wherein the mold opening / closing drive source is an electric servo motor, and the load detecting means detects a load of the mold opening / closing mechanism by measuring a torque of the electric servo motor. In Claim 1 or 2,
The mold opening / closing device for a molding machine, wherein the allowable load range is set along a position axis or a time axis. In claim 3,
The mold opening / closing device of the molding machine, wherein the allowable range of load described above can be arbitrarily set interactively with the display screen.

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