JP2003204687A - Injection molding machine and method of protecting the injection molding machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding machine of a simple structure which can realize sure protection of a dynamic brake device, combined with a motor mounted as an actuator from overloaded state, and to provide a method of protecting the injection molding machine. <P>SOLUTION: This injection molding machine includes a motor, a dynamic brake device, which is combined with the motor and consumes the regenerated power of the motor as the load, and a controller which outputs a drive output signal to the dynamic brake device and controls the dynamic brake device, consuming the regenerated power of the motor; this controller estimates the load applied to the dynamic brake device, based on the drive output signal outputted to the dynamic brake device, and determines whether the dynamic brake device is in overload state, based on the load estimated. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding machine and a method of protecting the injection molding machine, and more particularly, to a dynamic brake device combined with an electric motor used as an actuator in an injection device, a mold clamping device or the like. The present invention relates to an electric injection molding machine, a hybrid injection molding machine, and a method for protecting the injection molding machine.

[0002]

2. Description of the Related Art An electric injection molding machine employs an electric motor as a drive source. In addition, there is a so-called hybrid injection molding machine as an injection molding machine that incorporates the advantages of both the hydraulic injection molding machine and the electric injection molding machine.
A motor is also used in this hybrid type injection molding machine.

That is, in the injection molding machine, the motor is operated to rotate and advance the injection screw, move the movable platen forward and backward, and move the ejector pin of the molded product ejector device forward and backward. Further, as a device for consuming regenerative electric power of the motor, a dynamic brake device is combined with various motors of the injection molding machine.

FIG. 1 is a schematic configuration diagram of a drive circuit of a motor provided in an electric injection molding machine as an example of a conventional injection molding machine.

Referring to FIG. 1, the drive circuit includes a converter section 2, an inverter section 3, a dynamic brake device 5, and a capacitor 6.

The converter unit 2 converts alternating current from the three-phase alternating current power supply 1 into direct current. The inverter unit 3 converts the direct current from the converter unit 2 into an alternating current and supplies the alternating current to the motor 4. The dynamic braking device 5 is connected to the DC link unit 8 between the converter unit 2 and the inverter unit 3. The smoothing capacitor 6 is connected to the DC link unit 8 between the converter unit 2 and the dynamic brake device 5.

The dynamic brake device 5 includes a regenerative resistor section 5-1 for consuming regenerative electric power, and a switch element 5-2 which is on / off controlled by the controller 9. The dynamic braking device 5 functions as a device for consuming the regenerative electric power of the motor 4.

In such a drive circuit, when the motor 4 decelerates and enters the regenerative operation, the controller 9 outputs a control signal for turning on / off the switch element 5-2. When the switch element 5-2 is turned on, the regenerative electric power from the motor 4 is consumed by the regenerative resistance unit 5-1.

When the regenerative power from the motor 4 is large,
The dynamic brake device 5 may be overloaded, and the regenerative resistance part 5-1 may be burned out. Therefore, it is necessary to detect such an overload state and stop the motor 4 or reduce the torque or speed of the motor 4 to reduce the load of the motor 4 in order to protect the drive circuit of the motor 4. for that reason,
The dynamic brake device 5 is usually provided with a thermal relay 7 that detects that the regenerative power exceeds a predetermined value. Alternatively, in place of the thermal relay 7, a current detector or a voltage detector (not shown) that detects that the dynamic brake device 5 is overloaded is installed.

[0010]

By the way, in the above-mentioned electric injection molding machine, in order to efficiently produce many molded products in a short time, for example, in the mold clamping process and the injection process, the motor 4 is driven in a short cycle. Acceleration / deceleration is required. As a result, the motor 4 is frequently regenerated. Therefore, the regenerative electric power of the motor 4 increases and the dynamic
It is important for the electric injection molding machine to reliably prevent the brake device 5 from becoming overloaded from the viewpoint of efficiently producing a desired molded product.

On the other hand, like the above-mentioned conventional electric injection molding machine, if a dedicated protection device such as a thermal relay 7 or a current detector or a voltage detector is provided in order to protect the dynamic brake device 5, the A large device is required as an injection molding machine. This is not desirable from the viewpoint of securing a space for disposing the electric injection molding machine and the viewpoint of manufacturing cost.

Therefore, an object of the present invention has been made in view of the above problems, and a dynamic brake device to be combined with an electric motor (motor) mounted as an actuator is provided with a simple structure and can be reliably operated from an overload state. An object of the present invention is to provide an injection molding machine that can realize the above protection and a method of protecting the injection molding machine.

[0013]

[Means for Solving the Problems] The above object is to provide an electric motor,
A dynamic brake device that is combined with the electric motor and consumes regenerative power of the electric motor as a load, and outputs a drive output signal to the dynamic brake device,
The dynamic braking device includes a controller that controls consumption of regenerative power of the electric motor, and the controller estimates a load applied to the dynamic braking device based on a drive output signal output to the dynamic braking device. Then, it is achieved by an injection molding machine characterized by determining whether or not the dynamic brake device is in an overloaded state based on the estimated load.

According to the above invention, in order to reliably protect the dynamic brake device combined with the electric motor from the overload condition, it is possible to judge whether or not the dynamic brake device is in the overload condition with a simple structure. Can be done.

Further, the dynamic brake device includes a switch element that is on / off controlled by the drive output signal output from the controller, and turns on the drive output signal for turning on the switch element and the switch element. The duty may be calculated by filtering the drive output signal, and the load applied to the dynamic brake device may be estimated based on the duty.

Further, the above object is to estimate a load applied to the dynamic brake device based on a drive signal input to a dynamic brake device provided in an injection molding machine, and to perform the dynamic load based on the estimated load. Determining whether the braking device is in an overloaded state, determining that the dynamic braking device is in an overloaded state, and if the time during which the overloaded state continues exceeds a predetermined time, It is also achieved by a method of protecting an injection molding machine, which is characterized by protecting the dynamic braking device.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Hereinafter, an embodiment of the present invention will be described by taking an electric injection molding machine as an example.

FIG. 2 is a side view showing a schematic configuration of the electric injection molding machine 10 according to the first embodiment of the present invention. Figure 2
Referring to FIG. 1, the electric injection molding machine 10 includes an injection device 20 and a mold clamping device 50.

The injection device 20 includes a heating cylinder 21, and a hopper 22 is arranged in the heating cylinder 21. Further, a screw 23 is arranged in the heating cylinder 21 so as to be capable of advancing and retracting and rotating. The rear end of the screw 23 is rotatably supported by the support member 24. A metering motor 25 such as a servomotor is attached to the support member 24 as a drive unit, and the rotation of the metering motor 25 is transmitted to the screw 23 via a timing belt 27 attached to an output shaft 26 of the metering motor 25. It

The injection device 20 further includes a screw shaft 28 rotatably in parallel with the screw 23. The rear end of the screw shaft 28 is connected to the injection motor 29 via a timing belt 31 attached to the output shaft 30 of the injection motor 29 such as a servo motor. Therefore, the screw shaft 28 is rotated by the injection motor 29. The front end of the screw shaft 28 is screwed with a nut 32 fixed to the support member 24. Therefore, when the injection motor 29, which is a drive unit, is driven and the screw shaft 28 is rotated through the timing belt 31, the support member 24 can be moved forward and backward, and as a result, the screw 23 can be moved forward and backward.

The mold clamping device 50 includes a movable platen 52 to which a movable mold 51 is attached and a fixed platen 54 to which a fixed mold 53 is attached. Movable platen 5
2 and the fixed platen 54 are connected by a tie bar 55. The movable platen 52 is slidable along the tie bar 55. The mold clamping device 50 also includes a toggle mechanism 57 having one end connected to the movable platen 52 and the other end connected to the toggle support 56. A ball screw shaft 59 is rotatably supported at the center of the toggle support 56.

A nut 61 formed on a crosshead 60 provided on the toggle mechanism 57 is screwed onto the ball screw shaft 59. A pulley 62 is arranged at the rear end of the ball screw shaft 59, and a timing belt 65 is stretched between an output shaft 64 of a mold clamping motor 63 such as a servo motor and the pulley 62.

Therefore, in the mold clamping device 50, when the mold clamping motor 63, which is the drive unit, is driven, the rotation of the mold clamping motor 63 is transmitted to the ball screw shaft 59, which is the drive transmission unit, via the timing belt 65. And the ball screw shaft 5
The movement direction is converted from the rotational movement to the linear movement by the 9 and the nut 61, and the toggle mechanism 57 operates. When the toggle mechanism 57 operates, the movable platen 52 moves the tie bar 5
Sliding along 5, the mold is closed, clamped and opened.

As described above, in the electric injection molding machine 10 according to this embodiment, the electric motors such as the measuring motor 25, the injection motor 29, and the mold clamping motor 63 are adopted as the actuators, and the measuring, injection, and Each operation such as mold clamping is continuously performed.

By the way, when the motor is decelerated, regenerative electric power is generated. As a device for consuming such regenerated electric power, a dynamic brake device is combined with each motor of the electric injection molding machine 10.

FIG. 3 is a schematic configuration diagram of a drive circuit of the three-phase motor 104 provided in the electric injection molding machine 10 according to the first embodiment of the present invention and combined with the dynamic brake device 105.

Referring to FIG. 3, the drive circuit includes a converter section 102, an inverter section 103, a dynamic brake device 105, and a capacitor 106.

The converter section 102 includes a three-phase AC power source 10
Convert AC from 1 to DC. Inverter unit 103
Converts the direct current from the converter unit 102 into alternating current and supplies the alternating current to the three-phase motor 104. dynamic·
The braking device 105 is connected to the DC link unit 108 between the converter unit 102 and the inverter unit 103.
A controller 109 is connected to the dynamic braking device 105. The smoothing capacitor 106 includes the converter unit 102 and the dynamic brake device 105.
And is connected to the DC link unit 108.

The dynamic brake device 105 includes a regenerative resistor unit 105-1 for consuming regenerative electric power, and a switch element 105-2 which is on / off controlled by the controller 109. Dynamic braking device 10
5 functions as a device for consuming the regenerative power of the three-phase motor 104.

When the three-phase motor 104 decelerates, the three-phase motor 104 acts as a generator rather than an electric motor. Therefore, the current generated by the three-phase motor 104 flows back to the DC link unit 108, and the voltage of the DC link unit 108 temporarily increases. In particular, when the molding cycle is short, the control for accelerating and decelerating the three-phase motor 104 is frequently performed, so that the voltage of the DC link unit 108 tends to be high.

When the voltage of the DC link unit 108 exceeds the reference value, the controller 109 causes the switch element 105-
A drive output signal for turning on 2 is output. When the switch element 105-2 is turned on, the current from the three-phase motor 104 flows into the regenerative resistance unit 105-1 and the regenerative power from the three-phase motor 104 is consumed by the regenerative resistance unit 105-1.

If the switching element 105-2 is turned on for a long time, the power consumption time by the regenerative resistance unit 105-1 becomes long and the load on the dynamic brake device 105 becomes large. In other words, the magnitude of the load applied to the dynamic braking device 105 depends on the switching element 1
It is proportional to the duty of the drive output signal for turning the 05-2 on and off.

Focusing on this point, in the present embodiment, the controller 109 filters the drive output signal (ON signal and OFF signal) to the switch element 105-2. The controller 109 estimates the load applied to the dynamic brake device 105 based on the duty obtained by the filtering. The controller 109 determines whether the dynamic braking device 105 is in an overloaded state based on the estimated load.

When it is determined that the regenerative resistance unit 105-1 is in the overload state, the controller 109 operates to protect the regenerative resistance unit 105-1 from the overload state. The controller 109 outputs, for example, a signal for stopping the molding operation of the electric injection molding machine 10 to a main controller (not shown) of the electric injection molding machine 10 as an operation of protecting the regenerative resistance unit 105-1 from an overload state. To do.

FIG. 4 shows the controller 109 in FIG.
2 is a schematic configuration diagram of FIG. Referring to FIG. 4, the controller 109 is generally composed of an input unit 109-1, a control unit 109-2, a drive circuit 109-3, and the like. In addition, the arrow shown in FIG. 4 shows the input or output of the information or command mentioned later.

Information about the voltage of the DC link unit 108,
Deceleration command of the three-phase motor 104 based on the molding pattern,
The system control information generated based on a feedback signal from a predetermined sensor arranged in the dynamic brake device 105 is input to the input unit 10 of the controller 109.
9-1 is input. In the following example, a case will be described in which information about the voltage of the DC link unit 108 is input to the input unit 109-1.

The input unit 109-1 outputs the input system information to the control unit 109-2. Control unit 109-2
When it is determined that the voltage of the DC link unit 108 exceeds the reference value, the drive circuit 105 outputs a drive command to output a drive output signal that turns on the switch element 105-2.
Output to -3. Based on this command, the regenerative electric power from the three-phase motor 104 shown in FIG. 3 is consumed by the regenerative resistance unit 105-1.

The control unit 109-2 has a switch element 105.
The drive output signal (ON signal and OFF signal) output to -2 is filtered to detect the duty, and the load applied to the dynamic brake device 105 is estimated based on the duty. Control unit 109-2
Further determines from the estimated load whether the dynamic braking device 105 is overloaded.

By the way, when the regenerative electric power that greatly exceeds the rating of the regenerative resistor unit 105-1 of the dynamic brake device 105 momentarily acts from the three-phase motor 104, the drive output signals (on signal and off signal) are generated. It seems that the duty becomes large and it is in the state of complete overload.

However, in practice, even with such regenerative power, the regenerative resistor section 105-1 can allow a large duty if the operating time is relatively short. In view of this situation, the controller 10
The control unit 109-2 of 9 performs filtering using a time constant in accordance with the characteristic of the regenerative resistance unit 105-1.
The duty of the drive output signal is detected to estimate the load. Here, the time constant is one parameter that determines the strength of filtering.

The filtering in this embodiment will be described below. FIG. 5 is a graph showing a current pattern flowing through the regenerative resistance unit 105-1.

Referring to FIG. 5, the horizontal axis represents time, and the vertical axis represents the current value of the current flowing through the regenerative resistor section 105-1. The current pattern shown in FIG.
9 and the pattern of the drive output signal (ON signal and OFF signal) output to the switch 109-2 or the switch element 105-2 (shown by dotted lines in FIGS. 6 and 7). This signal pattern is determined by a molding pattern that is predetermined in the electric injection molding machine 10. When the drive output signal is the ON signal, the current value becomes the maximum value. When the drive output signal is an off signal, the current value becomes the minimum value (zero value).

The filtering is performed for the drive output signals (ON signal and OFF signal) by dividing the filter time constant into two types, a small time constant τ ₁ and a large time constant τ ₂ .

FIG. 6 is a graph showing a current pattern (waveform) estimated for a drive output signal (ON signal and OFF signal) through filtering using a small time constant τ ₁ .

Referring to FIG. 6, the horizontal axis represents time, and the vertical axis represents the calculated value (duty) of the current of the regenerative resistor unit 105-1 after the filtering. When the pattern using the time constant τ _{1 is applied} to the pattern of the drive output signal (on signal and off signal) (shown by the dotted line in FIG. 6), the waveform shown by the solid line in FIG. 6 is output. here,
The time constant τ ₁ is a small time constant used for filtering that sets a load threshold that can be tolerated for a short time.

Further, in FIG. 6, A is a regenerative resistor unit 105-
1 is a maximum load value (hereinafter, referred to as “maximum allowable value”) in a range in which no burnout occurs, and is a predetermined value (hereinafter, “initial maximum allowable value”).

As shown in FIG. 6, when a drive output signal for turning on the switch element 105-2 is output from the controller 109 shown in FIG. 3, a current flows through the regenerative resistor unit 105-1 and the waveform rises to the right. Becomes Therefore, when the duty is added and exceeds the initial maximum allowable value of the duty of the regenerative resistor unit 105-1, the regenerative resistor unit 105-1 is overloaded. In order to prevent such a state, the threshold value L _{1 of the} load that can be allowed for a short time is set as a value slightly smaller than the initial maximum allowable value A.

FIG. 7 is a graph showing a current pattern (waveform) estimated by filtering the drive output signal (ON signal and OFF signal) using a large time constant τ ₂ .

Referring to FIG. 7, the horizontal axis represents time, and the vertical axis represents the calculated value (duty) of the current of the regenerative resistor unit 105-1 after the filtering. In FIG. 7, with respect to the drive output signals (on signal and off signal) indicated by the dotted line,
When the filtering using the time constant τ ₂ is applied, the waveform shown by the solid line in FIG. 7 is output. Where time constant τ
₂ is a large time constant used for filtering that sets a load threshold that can be tolerated for a long time.

The waveform of the current pattern shown in FIG. 7 has a smaller slope than the waveform shown in FIG. That is, even if the drive output signal for turning on the switch element 105-2 is output, the speed at which the duty is added is slower than in the case shown in FIG. Even if the drive output signal for turning off the switch element 105-2 is output, the speed at which the duty is subtracted is slower than in the case shown in FIG.

In the electric injection molding machine 10, the same molding operation is usually repeated continuously. Figure 8
When the molding condition 1 or the molding condition 2 is set as the driving condition and the molding operation is repeated, the duty value filtered by using the time constant τ ₁ shown in FIG. 6 and the time shown in FIG. It is a graph which shows the value of the duty filtered using the constant (tau) ₂ .

Referring to FIG. 8, when the molding condition 1 is set as the driving condition, the duty value when filtering is performed using the time constant τ ₁ (in FIG. 8, line 300).
Indicates a duty value (shown as line 400 in FIG. 8) when the filtering is performed using the time constant τ ₂ and increases in a short time.

On the other hand, as described above, when the filtering using the time constant τ ₂ is applied, the speed at which the duty is subtracted is slower than the subtracting speed when the filtering using the time constant τ ₁ is applied. (See Figure 7). Therefore, as shown in FIG. 8, when a certain time elapses, the duty when filtering is performed using the time constant τ ₁ (in FIG. 8,
Finally, the duty (shown as line 400 in FIG. 8) when filtered using the time constant τ ₂ also becomes the same constant value.

Also, when the molding condition 2 is set as the driving condition, the duty value when filtering is performed using the time constant τ ₁ as in the case where the molding condition 1 is set as the driving condition (FIG. 8). Medium, shown as line 500)
Is increased in a short time as compared with the duty value (shown as line 600 in FIG. 8) when filtering is performed using the time constant τ ₂ . Also, after a certain period of time,
The duty (shown as line 500 in FIG. 8) when filtering is performed using the time constant τ ₁ is also the time constant τ ₂
The duty (shown as line 600 in FIG. 8) in the case where filtering is performed by using () finally becomes the same constant value.

By the way, as shown in FIGS. 6 and 8, at the beginning of operation of the electric injection molding machine 10, it is possible to allow a large duty within a range not exceeding the initial maximum allowable value A. However, the regenerative resistor unit 1 caused by heat radiation etc.
Due to the deterioration of the characteristics of 05-1, the maximum allowable value of the duty (represented by the dotted line in FIG. 8) of the regenerative resistance unit 105-1 decreases with the passage of time, and finally becomes a constant value.

Therefore, when the electric injection molding machine 10 is continuously operated for a long time, it is a little smaller than the maximum allowable value of the duty of the regenerative resistance unit 105-1 and finally becoming constant. The value is set as the overload threshold L _{2 that} can be tolerated for a long time, and the regenerative resistor unit 105-1 is protected from the overload state.

When the molding condition 1 is set as the driving condition, if the electric injection molding machine 10 is continuously operated for a long time, the maximum allowable duty of the regenerative resistor 105-1 will be exceeded, but the threshold L ₂ At the time point Δt (see FIG. 8), the command to stop the three-phase motor 140 in order to protect the regenerative resistance unit 105-1 is output.

When the molding condition 2 is set as the driving condition, the duty is smaller than the threshold value L ₂ , so that the electric injection molding machine 10 can be continuously operated.

It should be noted that when the filtering is performed using the time constant τ ₁ , the time from the start of the shaping to the threshold value L ₁ or the duty is started when the filtering is performed using the time constant τ _2. The time from when the threshold value reaches the threshold L ₂ (see FIG. 8) is Δt.

FIG. 9 shows the duty at any time.
And the duty is a threshold value L from the start of molding. ₁Or L_TwoTo
6 is a graph showing the relationship with the time Δt until the time. Figure 9
In the figure, the horizontal axis represents duty and the vertical axis represents time Δt.

Referring to FIG. 9, when filtering is performed using the time constant τ ₁ (indicated by a chain line in FIG. 9)
Also, when filtering is performed using the time constant τ ₂ (indicated by the chain double-dashed line in FIG. 9), when the duty is large, the time to reach the threshold L ₁ or L ₂ is short, and the duty is When it is small, the time to reach the threshold L ₁ or L ₂ is long.

Further, as described above, by performing filtering using a plurality of filter time constants, the characteristics of the regenerative resistor unit 105-1 (shown by the dotted line in FIG. 8) are considered,
The sensitivity to load fluctuations can be adjusted to easily approximate the maximum allowable regenerative resistance. Therefore, it is possible to improve the accuracy of protecting the regenerative resistor unit 105-1 from an overload state.

Therefore, based on the above filtering,
The control unit 109-2 uses the dynamic brake device 10
When it is determined that the regeneration resistance unit 105-1 of No. 5 is in the overload state, the control unit 109-2 outputs a signal for stopping the molding operation of the electric injection molding machine 10 to the electric injection molding machine 10.
Output to a main controller (not shown) of the electric injection molding machine 1
Stops or suppresses the operation of 0, or gives a warning to the operation. This protects the regenerative resistor unit 105-1 from overload.

As a result, the regenerative electric power generated by the three-phase motor 104 is consumed by the regenerative resistance unit 105-1 and the regenerative resistance unit 1 of the dynamic brake device 105.
By providing the threshold value according to the characteristics of 05-1, the dynamic brake device 105 can be protected accurately. In addition, the electric injection molding machine 10 can be braked efficiently.

Further, in the present embodiment, an example in which two threshold values are provided has been described, but by further providing the threshold values, the regenerative resistance unit 105-1 of the dynamic brake device 105 is provided.
Can be further approximated to the characteristic of. That is, it is possible to set, in the electric injection molding machine 10, molding conditions that can be used up to near the maximum allowable value of the regenerative resistance unit 105-1 of the dynamic brake device 105. As a result, the molding cycle of the electric injection molding machine 10 can be further accelerated, and the load on the three-phase motor 104 can be further increased. Therefore, the electric injection molding machine 10 can make a molded product more efficiently.

In this way, the dynamic brake device 105 combined with the three-phase motor 104 mounted as an actuator can be reliably protected from an overload state with a simple structure using the controller 109, and the electric motor The injection molding machine 10 can be braked efficiently.

The types and values of the overload judgment threshold value or filter time constant are determined by the dynamic brake device 1.
It is appropriately determined according to the specification values such as the rated current and capacity of 05. Further, the motor 104 is not limited to the three-phase motor.

Further, in the above embodiment, the system control information input to the input unit 109-1 of the controller 109 is described by referring to the information about the voltage of the DC link unit 108, but the present invention is not limited to this. The deceleration command of the three-phase motor 104 based on the molding pattern may be used.

Next, a second embodiment of the present invention will be described. FIG. 10 is a schematic configuration diagram of a controller according to the second embodiment of the present invention. 10, those parts which are the same as those corresponding parts in FIG. 4 are designated by the same reference numerals, and a description thereof will be omitted.

In the above-described first embodiment, the controller 109 controls the dynamic brake device 10 based on the duty of the drive output signal to the switch element 105-1.
The load on 5 is estimated. In the second embodiment,
An overload of the dynamic brake device 105 is determined by combining a drive output signal which is a control signal output from the controller 109 and a readback value of the drive output signal. That is, the readback value is also filtered in the same manner as the drive output signal, and it is determined whether the dynamic brake device 105 is in the overload state.

For example, although the duty obtained based on the drive output signal (ON signal and OFF signal) is lower than the predetermined threshold, the duty obtained based on the readback value is lower than the predetermined threshold. Suppose it is expensive.

In this case, the control unit 109-2 continues to drive the dynamic brake device 105 despite the occurrence of some abnormality in the control signal system of the drive circuit 109-3, etc. -It can be determined that the brake device 105 is in the overload state. Based on such a determination, the controller 109 performs an operation of protecting the dynamic brake device 105 from an overload condition. This further increases the certainty of protecting the dynamic braking device from overload conditions.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited to the specific embodiments, and various modifications are possible within the scope of the gist of the present invention described in the claims. Can be modified and changed.

For example, although the electric injection molding machine has been described in the above-mentioned embodiments, the present invention is not limited to this. For example, a so-called hybrid in which the advantages of both the hydraulic injection molding machine and the electric injection molding machine are incorporated. It can also be applied to injection molding machines.

[0075]

As is apparent from the above detailed description, according to the injection molding machine and the method for protecting the injection molding machine of the present invention, a dynamic brake device combined with an electric motor mounted as an actuator is simplified. With such a structure, it is possible to surely protect from an overload state, and it is possible to brake the injection molding machine efficiently.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a drive circuit of a motor provided in an electric injection molding machine as an example of a conventional injection molding machine.

FIG. 2 is a side view showing a schematic configuration of the electric injection molding machine according to the first embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a drive circuit of a three-phase motor 104 provided in the electric injection molding machine 10 according to the first embodiment of the present invention and combined with a dynamic brake device 105.

4 is a schematic configuration diagram of a controller 109 in FIG.

FIG. 5 is a graph showing a current pattern flowing through a regenerative resistor section 105-1.

FIG. 6 is a graph showing a current pattern (waveform) estimated for a drive output signal (on signal and off signal) through filtering using a small time constant τ ₁ .

FIG. 7 is a graph showing a current pattern (waveform) estimated for a drive output signal (ON signal and OFF signal) through filtering using a large time constant τ ₂ .

8 is a diagram illustrating a case where a molding condition 1 or a molding condition 2 is set as a driving condition and a molding operation is repeatedly performed, and a duty which is filtered by using a time constant τ ₁ illustrated in FIG. It is a graph which shows the value of the duty filtered using the constant (tau) ₂ .

FIG. 9 is a duty at an arbitrary time point and a time Δ from that time point until the duty reaches the threshold value L ₁ or L _2.
It is the graph which showed the relationship with t.

FIG. 10 is a schematic configuration diagram of a controller according to a second embodiment of the present invention.

[Explanation of symbols]

10 Electric injection molding machine 25 Weighing motor 29 injection motor 63 Mold clamping motor 101 Three-phase AC power supply 102 converter 103 Inverter section 104 three-phase motor 105 Dynamic braking device 105-1 Regenerative resistor section 105-2 switch element 106 capacitor 108 DC link section 109 controller 109-1 Input section 109-2 control unit 109-3 drive circuit

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4F206 JA07 JP14 JP15 JT12 JT32                 5G004 AA05 AB02 BA04 DB03 DC04                       DC05                 5G013 AA04 BA01 CA10                 5H530 AA02 BB32 CC06 CC23 CC25                       CE16 DD03 DD04 DD13 DD15                       EE01

Claims (9)

[Claims] 1. An electric motor, a dynamic brake device that is combined with the electric motor and consumes regenerative electric power of the electric motor as a load, and a drive output signal is output to the dynamic brake device. A controller for controlling consumption of regenerative electric power of the electric motor is included, wherein the controller controls the dynamic braking device based on a drive output signal output to the dynamic braking device.
An injection molding machine characterized by estimating a load applied to a brake device and determining whether or not the dynamic brake device is in an overloaded state based on the estimated load. 2. The injection molding machine according to claim 1, wherein the dynamic brake device includes a switch element that is on / off controlled by the drive output signal output from the controller. 3. The controller calculates a duty of a drive output signal that turns on the switch element and a duty of a drive output signal that turns off the switch element, and estimates a load applied to the dynamic brake device based on the duty. 2. The method according to claim 2, wherein
The described injection molding machine. 4. The controller calculates the duty by filtering a drive output signal that turns on the switch element and a drive output signal that turns off the switch element. The described injection molding machine. 5. The dynamic brake device further includes a regenerative resistor unit that consumes regenerative power of the electric motor, and the filtering has a plurality of time constants that match characteristics of the regenerative resistor unit of the dynamic brake device. The injection molding machine according to claim 4, characterized in that: 6. The controller determines that the regenerative resistor section of the dynamic brake device is in an overload state based on the result of the filtering, and the time period during which the overload state continues is within a predetermined time. If so, the dynamic brake device is allowed to be loaded to a predetermined value, and if the time during which the overload state continues exceeds the predetermined time, the dynamic brake device is activated. The injection molding machine according to claim 4 or 5, which performs a protective operation. 7. The controller combines the drive output signal and a readback value of the drive output signal to determine whether the dynamic braking device is overloaded. 7. The injection molding machine according to any one of 6 to 6. 8. A dynamic machine provided in an injection molding machine
The load applied to the dynamic brake device is estimated based on the drive signal input to the brake device, and it is determined whether the dynamic brake device is in an overloaded state based on the estimated load. A method for protecting an injection molding machine, characterized in that the dynamic braking device is protected when it is determined that the braking device is in an overloaded state and the duration of the overloaded state exceeds a predetermined time. . 9. The drive output signal is filtered by using a plurality of time constants to calculate a duty, and the load applied to the dynamic brake device is estimated based on the duty. 8. The method for protecting an injection molding machine according to 8.