JP5926658B2 - Lifting magnet working machine - Google Patents

Description

  The present invention relates to a lifting magnet working machine that performs lifting work of metal scrap such as iron with a lifting magnet.

  As a working machine used in a work site handling metal scrap such as iron, there is a lifting magnet working machine that is lifted by being attracted by a magnetic force of a lifting magnet. For example, Patent Document 1 (Japanese Patent Laid-Open No. 2004-299818). The engine, a plurality of hydraulic pumps driven by the engine, a hydraulic motor driven by the discharge oil of one of the hydraulic pumps, a generator driven by the hydraulic motor and performing a power generation action, A self-propelled lifting magnet working machine is disclosed that includes a lifting magnet attached to the tip of an arm and powered by the generator.

JP 2004-299818 A

  In the above-described prior art lifting magnet working machine, by controlling the output voltage from the generator to the lifting magnet according to the number of engine revolutions, when the engine is operated at low speed as a measure to reduce noise and fuel consumption, We are trying to suppress the influence of the increase and decrease of the absorption torque on the working speed of the work equipment.

  However, since the engine speed greatly fluctuates due to fluctuations in the load on the work machine side, the output voltage to the lifting magnet also fluctuates due to control, and there is a possibility that the adsorbate falls when the suction force decreases. In addition, since fluctuations in engine speed also affect the amount of power generated by the generator via the hydraulic pump and hydraulic motor, it is more difficult to control the output voltage to the lifting magnet, and the operation may become unstable. Concerned.

  The present invention has been made in view of the above, and an object thereof is to provide a lifting magnet working machine capable of obtaining a stable attractive force.

(1) In order to achieve the above object, the present invention provides a traveling body, a revolving body provided on the traveling body so as to be able to turn, a working machine provided on the revolving body, and a tip of the working machine. A lifting magnet working machine provided with a lifting magnet that attracts an object by electric power supplied from a power supply, wherein the current, voltage, and polarity of the electric power supplied from the power supply to the lifting magnet are adjusted. A power adjustment means; a supply current detection means for detecting the current supplied to the lifting magnet via the supply power adjustment means; and a voltage supplied to the lifting magnet via the supply power adjustment means. a supply voltage detecting means for, based on the detection result from the supply current detecting means, said lifting magnetic Tsu As the current supplied is a predetermined pickup operation current value, and controls the supply power regulating means, when said supply voltage detection result from the detection means reaches a predetermined upper limit voltage value And a control device that adjusts the adsorption operation current value based on a ratio between a predetermined standard voltage value and a voltage value detected by the supply voltage detection means .

(2) In the above (1) , preferably, a notification means for notifying an operator when a detection result from the supply voltage detection means exceeds a predetermined upper limit voltage value is provided.

(3) In the above (1), preferably, the supply power adjustment means is configured using a plurality of thyristors, and adjusts current and voltage in the power supplied from the power source to the lifting magnet. A circuit, and an H bridge circuit configured to switch polarity of the current and the voltage in the power supplied from the thyristor bridge rectifier circuit to the lifting magnet, the control device including the circuit, Based on the detection result from the supply current detection means, the thyristor bridge rectifier circuit is controlled so that the current supplied to the lifting magnet becomes the predetermined adsorption operation current value.

  A lifting magnet working machine capable of obtaining a stable suction force can be provided.

It is a figure showing roughly the whole composition of the lifting magnet working machine concerning one embodiment. It is a figure which extracts and shows the lifting magnet drive circuit which controls a lifting magnet with a control apparatus. It is a flowchart which shows the electric power supply process to a lifting magnet. It is a flowchart which shows the supply power control process at the time of the adsorption power output in an electric power supply process. It is a figure which shows roughly the electric current constant process in a power supply control process. It is a figure which shows the relationship between the output voltage from a thyristor bridge rectifier circuit, and the electric power supplied to a lifting magnet in the same time-axis.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram schematically showing an overall configuration of a lifting magnet working machine according to the present embodiment.

In FIG. 1, the lifting magnet working machine includes a lower traveling body 100, an upper revolving body 101 that is pivotably mounted on the upper portion of the lower traveling body 100, and a vertically movable portion on the front portion of the upper revolving body 101. And a front work machine 102 connected thereto. The upper swing body 101 includes a power source chamber 103 in which an engine serving as a power source, a hydraulic pump, a generator, a power storage device, and the like are built, an operation lever (not shown), an adsorption release operation button 8, and a display / setting device. 9 and a driver's cab 104 provided with a notification device 10 and the like (described later).

  A generator 1 (see FIG. 2 below) disposed in the power source chamber 103 is configured to generate power by being driven by pressure oil from an engine or a hydraulic pump driven by the engine.

  The lower traveling body 100 includes left and right traveling motors 105 that are driven by pressure oil from a hydraulic pump, and travels when the traveling motor 105 is rotationally driven.

  The front work machine 102 includes a boom 106 that is pivotably connected to the front portion of the upper swing body 101, an arm 107 that is pivotally connected to the tip of the boom 106, and an arm 107. A lifting magnet 108 is connected to the tip so as to be pivotable in the front-rear direction, and is magnetized by supplied power to attract a metal such as iron. The boom 106, the arm 107, and the lifting magnet 108 are rotationally driven by a boom hydraulic cylinder 109, an arm hydraulic cylinder 110, and a lifting magnet hydraulic cylinder 111 that are driven by pressure oil from a hydraulic pump, respectively.

  The driver's cab 104 is provided with a driver's seat (not shown) where an operator is seated. The operator operates an operation lever (not shown) for operating the front work machine 102, the upper swing body 101, and the like from the seating position of the driver's seat, an adsorption release operation button 8 for operating adsorption / release of the lifting magnet 108, and display of various information. The display / setting device 9 for performing settings and the notification device 10 such as a speaker are operated (see FIG. 2).

  FIG. 2 is a diagram showing a lifting magnet driving circuit for driving and controlling the lifting magnet 108 together with a control device.

  In FIG. 2, a lifting magnet drive circuit 11 (supplied power adjusting means) is configured using a lifting magnet 108 driven by power supplied from the generator 1 as a three-phase AC power supply and a plurality of thyristors 2a to 2f. The thyristor bridge rectifier circuit 2 that adjusts the current and voltage in the electric power supplied from the generator 1 to the lifting magnet 108 and a plurality of transistors 3a to 3d, and the thyristor bridge rectifier circuit 2 to the lifting magnet 108. An H bridge circuit 3 for switching the polarity of the supplied current and voltage, a supply current detection circuit 4 (supply current detection means) for detecting a current supplied to the lifting magnet 108 via the H bridge circuit 3, and a thyristor bridge H bridge times from rectifier circuit 2 3 is provided with a supply voltage detection circuit 5 (supply voltage detection means) for detecting the voltage of the power output to 3 and a capacitor 6 for smoothing the power output from the thyristor bridge rectifier circuit 2 and performing regeneration during polarity switching. It is controlled by the control device 7 that controls the operation of the entire lifting magnet work machine including the lifting magnet drive circuit 11.

  The thyristor bridge rectifier circuit 2 converts an AC power supply voltage supplied from the generator 1 into a DC power supply voltage, and is constituted by a bridge circuit including a plurality (six in this embodiment) of thyristors 2a to 2f. ing. In the present embodiment, the generator 1 is a three-phase AC power source, and performs three-phase full-wave rectification by the thyristor bridge rectifier circuit 2 and outputs it.

  In the thyristor bridge rectifier circuit 2, the cathode of the thyristor 2a is electrically connected to the positive line 11a of the lifting magnet drive circuit 11, the cathode of the thyristor 2b is electrically connected to the anode of the thyristor 2a, and the anode of the thyristor 2b. Is electrically connected to the negative line 11b, and the first output terminal 1a of the generator 1 is electrically connected to the anode of the thyristor 2a and the cathode of the thyristor 2b. Similarly, the cathode of the thyristor 2c is electrically connected to the positive line 11a of the lifting magnet drive circuit 11, the cathode of the thyristor 2d is electrically connected to the anode of the thyristor 2c, and the anode of the thyristor 2d is connected to the negative side The second output terminal 1b of the generator 1 is electrically connected to the anode of the thyristor 2c and the cathode of the thyristor 2d. The cathode of the thyristor 2e is electrically connected to the positive line 11a of the lifting magnet drive circuit 11, the cathode of the thyristor 2f is electrically connected to the anode of the thyristor 2e, and the anode of the thyristor 2f is connected to the negative line. The third output terminal 1c of the generator 1 is electrically connected to the anode of the thyristor 2e and the cathode of the thyristor 2f. The control terminals (gates) of the thyristors 2a to 2f are electrically connected to the thyristor bridge rectifier circuit driver 7a of the controller 7, and phase control is performed at a predetermined control angle by a control signal from the thyristor bridge rectifier circuit driver 7a. Is done.

  The thyristor bridge rectifier circuit 2 realizes three-phase full-wave rectification by controlling the thyristor with a predetermined control angle, but instead of this, PWM (Pulse Width Modulation) using an IGBT (Insulated Gate Bipolar Transistor) is realized. ) Control can also be used.

  The H bridge circuit 3 switches the polarity of current and voltage in the power supplied from the thyristor bridge rectifier circuit 2 to the lifting magnet 108, and includes a plurality (four in the present embodiment) of transistors 3a to 3d, Each of the transistors 3a to 3d is constituted by a bridge circuit including diodes (rectifier elements) 3e to 3h electrically connected between current terminals (between collector-emitter or source-drain).

  In the H-bridge circuit 3, one current terminal of the transistor 3a is electrically connected to the positive line 11a of the lifting magnet drive circuit 11, and one current terminal of the transistor 3b is electrically connected to the other current terminal of the transistor 3a. The other current terminal of the transistor 3b is electrically connected to the negative line 11b, and the first terminal 108a of the lifting magnet 108 is electrically connected to the other current terminal of the transistor 3a and one current terminal of the transistor 3b. Connected. Similarly, one current terminal of the transistor 3c is electrically connected to the positive line 11a of the lifting magnet drive circuit 11, and one current terminal of the transistor 3d is electrically connected to the other current terminal of the transistor 3c. The other current terminal of the transistor 3d is electrically connected to the negative line 11b, and the second terminal 108b of the lifting magnet 108 is electrically connected to the other current terminal of the transistor 3c and one current terminal of the transistor 3d. Has been. The cathodes of the diodes 3e to 3h are electrically connected to one current terminal of the transistors 3a to 3d, respectively, and the anodes of the diodes 3e to 3h are electrically connected to the other current terminals of the transistors 3a to 3d, respectively. Has been.

The control terminals of the transistors 3 a to 3 d (base or gate) is electrically connected to the H-bridge circuits driver 7b of the control device 7, the control signal (control current from H-bridge circuits driver 7b or ON-OFF control by the control voltage). For example, the control signal from the H-bridge circuits driver 7b, 2 two transistors 3a, the 3d is turned ON (conductive state), the transistor 3a from the primary line 11a, the first terminal 108a of the lifting magnet 108, the second A current (excitation current of the lifting magnet 108) flows in the direction of the terminal 108b, the transistor 3d, and the negative line 11b. Hereinafter, the current direction at this time will be referred to as the forward direction. When the two transistors 3a and 3d are in the ON state (conductive state), the other two transistors 3b and 3c are controlled to be in the OFF state (cut-off state). Further, the control signal from the H-bridge circuits driver 7b, 2 two transistors 3b, when 3c is turned ON (conductive state), the second terminal 108b of the transistor 3c, the lifting magnet 108 from the primary line 11a, the first A current flows in the direction of the terminal 108a, the transistor 3b, and the negative side line 11b. Hereinafter, the direction of the current at this time is referred to as a reverse direction. When the two transistors 3b and 3c are in the ON state (conductive state), the other two transistors 3a and 3d are controlled to be in the OFF state (cut-off state).

  The supply current detection circuit 4 is connected in series to the first terminal 108 a side of the lifting magnet 108. The supply current detection circuit 4 detects a current supplied from the lifting magnet drive circuit 11 to the lifting magnet 108 and outputs the detection result to the control device 7 as a current detection signal.

  The supply voltage detection circuit 5 is electrically connected between the positive side line 11a and the negative side line 11b of the lifting magnet drive circuit 11. The supply voltage detection circuit 5 detects a voltage output from the thyristor bridge rectifier circuit 2 to the H bridge circuit 3 (that is, a voltage between the positive side line 11a and the negative side line 11b) and uses the detection result as a voltage detection signal. To the control device 7.

  The capacitor 6 smoothes the power output from the thyristor bridge rectifier circuit 2 and the current supplied to the lifting magnet 108 from the forward direction (the direction from the first terminal 108a to the second terminal 108b) (the second terminal). The energy stored in the lifting magnet 108 is absorbed and regenerated when switching from 108b to the first terminal 108a. The capacitor 6 is electrically connected between the positive line 11a and the negative line 11b of the lifting magnet drive circuit 11.

  In the above, the lifting magnet drive circuit 11 of the present embodiment constitutes supply power adjusting means for adjusting the current, voltage, and polarity in the power supplied from the generator 1 as a power source to the lifting magnet 108.

  The control device 7 controls the operation of the entire lifting magnet work machine including the lifting magnet drive circuit 11. That is, the control device 7 controls the lifting magnet drive circuit 11 based on an input from the adsorption / release operation button 8 for operating the adsorption / release of the lifting magnet 108 and a display / setting device 9 for displaying and setting various information. The power supply process is performed.

  Here, the power supply process in the control device 7 will be described.

  FIG. 3 is a flowchart showing power supply processing to the lifting magnet 108, and FIG. 4 is a flowchart showing supply power control processing at the time of suction power output in the power supply processing. In FIG. 3, the processing on the thyristor bridge rectifier circuit side is shown on the left side, the processing state on the H bridge circuit side is shown on the right side, and further arranged in time series in the vertical direction.

  As shown in FIG. 3, when receiving a suction signal from the suction release operation button 8 (step S10), the control device 7 performs phase control of the thyristor bridge rectifier circuit 2 by the thyristor bridge rectifier circuit driver 7a to form an H bridge circuit. The OE (overexciting) voltage is output to the third side (step S20), and the output is continued until the OE time elapses (step S30). Simultaneously with the start of phase control in step S20, the positive side of the H bridge circuit 3 is turned on by the H bridge circuit driver 7b (step S21). Subsequently, a supply power control process for controlling the power supplied to the lifting magnet 108 is performed (step S40).

As shown in FIG. 4, in the supply power control process, first, constant current control (described later) is performed (step S41), and then the average voltage Vave per unit time of power supplied to the lifting magnet 108 is predetermined. It is determined whether or not it is higher than an upper limit voltage Vmax (described later) (step S42). If the determination result in step S42 is NO, it is determined whether a release signal from the adsorption release operation button 8 has been input (step S43). If the determination result is NO, step until the determination result is YES. S41 and S42 are repeated. In step S42, if the determination result is YES, voltage monitoring control (described later) is performed (step S44), and then it is determined whether a release signal has been input (step S45). If the determination result in step S45 is NO, step S44 is repeated until the determination result is YES. When the determination result in step S43 or step S45 is YES, the supply power control process is terminated.

  Returning to FIG.

  In FIG. 3, when the supply power control process (step S40) is completed, the control device 7 blocks the positive polarity side of the H bridge circuit 3 by the H bridge circuit driver 7b (step S50). When the detection signal becomes a value that can be regarded as 0 (zero) (step S60), the H-bridge circuit driver 7b conducts the reverse polarity side of the H-bridge circuit 3 (step S70), and the state is maintained until the reverse excitation time elapses. When the reverse excitation time has elapsed, the reverse polarity side of the H bridge circuit 3 is blocked by the H bridge circuit driver 7b (step S90), and the process is terminated. At the same time, the reverse polarity side of the H bridge circuit 3 in step S90 is cut off, and simultaneously, the phase control of the thyristor bridge rectifier circuit 2 is stopped by the thyristor bridge rectifier circuit driver 7a, and the supply of power to the H bridge circuit 3 side is stopped. (Step S91).

Here, details of constant current control and voltage monitoring control in the power supply process will be described.

  FIG. 5 is a diagram schematically showing constant current control in the supply power control process.

As shown in FIG. 5, the current constant control of the present embodiment is such that the current of the power supplied from the generator (power source) 1 to the lifting magnet 108 via the lifting magnet drive circuit 11 (supply power adjusting means) Control is performed so as to obtain a predetermined adsorption operation current value It. The adsorption operation current value It is, for example, a rated value set for the lifting magnet 108. Here, the rated value means a value that can be used stably in design, and is different from an absolute maximum rated value or an instantaneous maximum value as an upper limit of use.

In the constant current control, a control value is calculated from the adsorption operation current value It and the detection result (current value Ia) from the supply current detection circuit 4 (supply current detection means) by a calculation unit 7c provided in the control device 7. And output to the thyristor bridge rectifier circuit driver 7a. The thyristor bridge rectifier circuit driver 7a controls the thyristor bridge rectifier circuit 2 based on the control value. FIG. 5 shows a case where the adsorption operation current It is given and PI (proportional integration) control is performed, and each variable indicates an integration time Ti and a gain Kp, respectively.

  The resistance value R of the lifting magnet 108 is approximately 4 (Ω), the inductance L is approximately 4 to 10 (H), and the time constant L / R is as large as approximately 1 to 3 (seconds). The requirement for response time and control cycle when performing control based on the above is relatively low, which is very advantageous in terms of ease of control for maintaining the stability of the suction force. Each constant is determined experimentally and empirically in consideration of the stability of the lifting magnet 108 and the like.

  In general, the magnetic flux φ generated by the coil such as the lifting magnet 108 is expressed by the following equation (Equation 1), where L is the inductance, I is the current, and N is the number of coil turns.

  φ = L * I / N (Formula 1)

  That is, when the inductance L is constant, the magnetic flux, that is, the attractive force is determined by the current I. Therefore, as in the present embodiment, the generated magnetic flux is controlled to be constant by controlling the lifting magnet drive circuit 11 so that the current supplied to the lifting magnet 108 becomes a predetermined adsorption operation current value It. Therefore, a stable suction force can be obtained even during the operation of sucking and transporting the object.

Further, the voltage monitoring control of the present embodiment is performed by detecting the voltage value of power supplied from the generator (power source) 1 to the lifting magnet 108 via the lifting magnet drive circuit 11 (supply power adjusting means), that is, supply voltage detection. When the detection result from the circuit 5 (supply voltage detection means) reaches a predetermined upper limit voltage value, the current is constant based on the ratio between the predetermined standard voltage value and the voltage value detected by the supply voltage detection circuit 5 The same control as the constant current control is performed while adjusting the adsorption operation current value in the control.

The transition from the constant current control to the voltage monitoring control is performed when the average voltage value Vave exceeds the upper limit voltage value Vmax, and the transition from the voltage monitoring control to the constant current control becomes Vave below the standard voltage value. Done in case.

  More specifically, in voltage monitoring control, a unit time (for example, 2 to 3 seconds) of power supplied from the generator (power source) 1 to the lifting magnet 108 via the lifting magnet drive circuit 11 (supply power adjusting means). ), The adsorption operation current value Itm is adjusted based on the ratio between the predetermined standard voltage value Vnorm and the average voltage value Vave.

  The following equation (Equation 2) is used for calculating the adsorption operation current value in the voltage monitoring control.

  Itm1 = Itm0 * (Vnorm / Vave) * Kh (Formula 2)

  In the above equation 2, Itm1 represents the adsorption operation current value after adjustment, Itm0 represents the adsorption operation current value before adjustment, Vnorm represents the standard voltage value, Vave represents the average voltage value, and Kh represents the gain constant. The adjustment of the adsorption operation current value Itm (that is, the calculation of Itm1) in the voltage monitoring control is performed at predetermined intervals.

  During the adsorption operation, there is a concern that the temperature of the lifting magnet 108 itself continues to rise due to the current flowing through the lifting magnet 108, but this is suppressed by performing voltage monitoring control as in this embodiment. be able to.

  The operation of the present embodiment configured as described above will be described with reference to the drawings.

  FIG. 6 is a diagram showing the relationship between the output voltage from the thyristor bridge rectifier circuit and the power supplied to the lifting magnet on the same time axis.

  In the lifting magnet working machine of the present embodiment, when the operator operates the adsorption release operation button 8 for operating the adsorption / release of the lifting magnet 108 to instruct the adsorption ON (step S10 in FIG. 3, time: t1). The control device 7 controls the phase of the thyristor bridge rectifier circuit 2 by the thyristor bridge rectifier circuit driver 7a to output an OE (over exciting) voltage to the H bridge circuit 3 side (step S20), and the OE time elapses. The output is continued until (step S30 in FIG. 3, time: t2 to t3). Simultaneously with the start of the phase control in step S20, the positive side of the H bridge circuit 3 is turned on by the H bridge circuit driver 7b (step S21 in FIG. 3). Subsequently, when the OE time has elapsed from the start of application of the OE voltage (time: t1) (time: t2), the voltage Vt1 that is the adsorption operation current It is applied, and the adsorption release operation button 8 is operated again to turn off the adsorption. Until instructed (time: t3), constant current control or voltage monitoring control is performed. FIG. 6 shows a case where only constant current control is performed. When the suction release operation button 8 is operated and suction OFF is instructed (time: t3), the control device 7 blocks the positive polarity side of the H bridge circuit 3 by the H bridge circuit driver 7b (step S50 in FIG. 3). Reference, time: t3) When the detection signal from the supply current detection circuit 4 reaches a value that can be regarded as 0 (zero) (step S60 in FIG. 3, time: t4), the H bridge circuit driver 7b reverses the H bridge circuit 3. The polarity side is turned on (step S70 in FIG. 3), and the state is maintained until the reverse excitation time elapses (step S80 in FIG. 3). When the reverse excitation time elapses (time: t5), the H bridge circuit driver The reverse polarity side of the H-bridge circuit 3 is blocked by 7b (step S90 in FIG. 3), and the process ends (time: t6).

  The effect in this Embodiment comprised as mentioned above is demonstrated.

  In the conventional lifting magnet working machine, the output voltage from the generator to the lifting magnet is controlled according to the engine speed, so that the generator is absorbed during low-speed engine operation as a measure to reduce noise and fuel consumption. We are trying to suppress the influence of the increase and decrease of the torque on the working speed of the work equipment. However, since the engine speed greatly fluctuates due to fluctuations in the load on the work machine side, the output voltage to the lifting magnet also fluctuates due to control, and there is a possibility that the adsorbate falls when the suction force decreases. In addition, since fluctuations in engine speed also affect the amount of power generated by the generator via the hydraulic pump and hydraulic motor, it is more difficult to control the output voltage to the lifting magnet, and the operation may become unstable. Concerned.

On the other hand, in the present embodiment, a lifting magnet 108 is provided at the front end of the front work machine 102 disposed on the upper swing body 101 and attracts an object with electric power supplied from the generator (power source) 1. A lifting magnet drive circuit 11 for adjusting the current, voltage and polarity in the electric power supplied from the generator 1 to the lifting magnet 108 and the lifting magnet 108 via the lifting magnet drive circuit 11. A supply current detection circuit 4 for detecting the supplied current, and based on the detection result from the supply current detection circuit 4, the current supplied to the lifting magnet 108 becomes a predetermined adsorption operation current value It. Controls the lifting magnet drive circuit 11 Since it is configured, it is possible to obtain a stable suction force even during operation of conveying by adsorbing the object.

  In addition, since it is configured to control a slow response current (adsorption operation current value It), the control cycle can be delayed, and the circuit and software can be controlled more easily.

  Furthermore, when a current is passed through the lifting magnet, the temperature rises due to its resistance, and the resistance value increases as the temperature rises.Therefore, when constant current control is performed, the amount of heat generation further increases and coil burnout, etc. In this embodiment, since the voltage is monitored at the same time and the current value is controlled to decrease when the voltage value increases, the attractive force can be maintained up to the upper limit of the lifting magnet performance.

DESCRIPTION OF SYMBOLS 1 Generator 2 Thyristor bridge rectifier circuit 2a-2f Thyristor 3 H bridge circuit 3a-3d Transistor 3e-3h Diode 4 Supply current detection circuit 5 Supply voltage detection circuit 6 Capacitor 7 Control apparatus 8 Adsorption release operation button 9 Display / setting apparatus 10 Notification device 11 Lifting magnet drive circuit 100 Lower traveling body 101 Upper turning body 102 Front work machine 103 Power source chamber 104 Driving room 105 Traveling motor 106 Boom 107 Arm 108 Lifting magnet 109 Boom hydraulic cylinder 110 Arm hydraulic cylinder 111 For lifting magnet Hydraulic cylinder

Claims (3)

A traveling body, a revolving body provided on the traveling body so as to be able to swivel, a working machine provided on the revolving body, and an object provided at a tip of the working machine and attracting an object by electric power supplied from a power source In a lifting magnet working machine equipped with a lifting magnet
Supply power adjusting means for adjusting current, voltage and polarity in the power supplied from the power source to the lifting magnet;
Supply current detection means for detecting the current supplied to the lifting magnet via the supply power adjustment means;
Supply voltage detection means for detecting the voltage supplied to the lifting magnet via the supply power adjustment means;
Based on the detection result from the supply current detection means, the supply power adjustment means is controlled so that the current supplied to the lifting magnet becomes a predetermined adsorption operation current value, and from the supply voltage detection means A control device that adjusts the adsorption operation current value based on a ratio between a predetermined standard voltage value and a voltage value detected by the supply voltage detection means when the detection result of the above reaches a predetermined upper limit voltage value ; A lifting magnet working machine characterized by comprising: In the lifting magnet working machine according to claim 1 ,
A lifting magnet working machine, comprising: a notifying means for notifying an operator when a detection result from the supply voltage detecting means exceeds a predetermined upper limit voltage value. In the lifting magnet working machine according to claim 1,
The supply power adjusting means is
A thyristor bridge rectifier circuit configured using a plurality of thyristors to adjust current and voltage in the power supplied from the power source to the lifting magnet;
An H-bridge circuit configured using a plurality of transistors, and switching polarity of the current and the voltage in the power supplied from the thyristor bridge rectifier circuit to the lifting magnet;
The control device controls the thyristor bridge rectifier circuit based on a detection result from the supply current detection means so that a current supplied to the lifting magnet becomes a predetermined adsorption operation current value. Features lifting magnet work machine.

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