RU2347038C2 - Method of controlling turning of mine excavator using electrical actuation and device to this end - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: present invention pertains to equipment used in mining for excavation and earth movement, more specifically to control of mine excavators using electrical actuation. The method involves, in excavation mode, limiting of the current to the turning motor armature to a threshold value of the control signal, equal to 20-30% of the shutoff current value. The state of the excavation mode is established from readings of sensors for length of cables, stroke length of lift arms, and sensor for actuating lift and the current to the turning motor armature is automatically limited. Proposal is also given of a device for implementing this method.

EFFECT: reduction of dynamic lateral loads on the working equipment of the mining excavator, which lead to fatigue accumulation in stress concentration zones in metal and fatigue flaking.

2 cl, 2 dwg

Description

The invention relates to equipment used in mining for excavation and soil movement, and more particularly to the control of electric motors for mining excavators.

Dynamic lateral loads on the construction of working equipment for mining excavators arise for two reasons: firstly, when working in rocky, poorly blown faces at the moment of sliding of the teeth along the inclined slope of the rock (in half the cases) and, secondly, when the operator turns on the drive in the mode of scooping rock mass. This leads to the accumulation of fatigue in zones of stress concentration in the metal and the appearance of fatigue cracks.

In scooping mode, when the bucket is immersed in soil, in violation of the operating instructions, the drivers sometimes turn on the turning drive, thereby creating significant lateral loads on the metal structures of the working equipment

Known protection of the rotation drive (1) in the transport mode by control signals that form static mechanical characteristics that make it impossible to obtain large moments on the shafts of the engine motors when the driving signals are supplied. The fact of the possibility of forming the value of the stop currents depending on the driving signals is shown by the authors, but the problem of protecting the working equipment is not solved.

Another analogue may be device (2), the principle of which is based on measuring the current value of the current and voltage of the motor armature. The device comprises a master, voltage regulator connected in series, current regulator, and current and voltage sensors. The device according to this invention is intended to provide smooth acceleration and braking of the platform (selection of kinematic gaps in the rotation mechanism) in transport mode. At the same time, the value of the stopping torque on the motor shaft is proportional to the value of the driving signal (the position of the lever of the drive controller) selected by the driver.

The specified device can be used to keep the platform from turning in the digging mode and transport mode with a corresponding change in the driving signal by the driver.

The disadvantage of this technical solution is that in the digging mode, the duration of the machinist’s exposure to the rotation drive significantly exceeds the time for choosing gaps. If this time is increased, then the time of the transport operation will increase, and therefore, the productivity of the excavator will decrease.

As a prototype, we consider a method for controlling an electric drive of turning an excavator and a device for its implementation (3), based on measuring the current value of the current and voltage of the armature of the turning engine. The threshold value of the static component of the armature current of the motor is set in advance, the derivative of the current value of the armature voltage is calculated, and it is compared with the current value of the armature current. In the event that the resulting value of the compared values of the armature current and the derivative with respect to the armature voltage is higher than the threshold, a control signal is generated, leading to a decrease in the maximum stop current of the rotation drive.

The device for implementing the rotation control method comprises a master, a voltage regulator and a current regulator connected in series to the excavator electric drive, as well as current and voltage sensors, additionally equipped with a summing amplifier, a differentiating unit, a threshold element and a key. One of the outputs of the current sensor is connected to a summing amplifier, the output of the voltage sensor is connected through a differentiating unit to the same summing amplifier, the output of the summing amplifier is connected through a threshold element and a key to the input of the current regulator. The nature of the operating mode of the rotation drive can be set based on a certain value of the moment of static resistance to rotation of the platform. If this moment does not exceed 4-8% of the maximum lock passport value, then the mode of transportation. If the static moment of resistance to rotation of the platform is more than 8% - digging mode.

The technical task of the proposed method and device for its implementation is to reduce the dynamic lateral loads on the working equipment of a career excavator, leading to the accumulation of fatigue in areas of stress concentration in the metal and the appearance of fatigue cracks.

The problem is solved by limiting the current of the armature motor of the turning threshold value of the control signal in the scooping mode. The current value of the armature motor of the turning motor in the scooping mode is limited to a value equal to 20-30% of the current lock value. The scooping mode is set according to the readings of the rope length sensors, the length of the handle, the lift drive sensor, the pressure drive sensor and limit the value of the armature current of the turning motor automatically.

A device for implementing a method of controlling a rotation drive, which allows to limit lateral loads on the working equipment, comprises rotation, lifting, pressure and rotational drive drives connected to the control unit. The device also contains a signal analysis unit, to which a rope length sensor, a handle stroke length sensor, a lift drive sensor are connected, and a signal analysis unit is connected to a control unit.

A sign of the regime of scooping rock is the coincidence of the following conditions:

- the bucket handle is located in an area limited by the vertical location of the handle and perpendicular to the boom;

- the movement should be in the direction of extension of the handle or on the rise of the bucket;

- lifting drive current value (I _n) has to meet the condition I _n ≥0,6 I _stopper.

According to the readings of the sensors of the length of the ropes and the length of the stroke of the handle, the fact of the bucket being in the digging zone is determined. The digging zone for excavators of the ECG type, Fig. 1, between the vertical (I) and horizontal (II) position of the handle at a certain interval of extension of the handle. From the transportation mode, the scooping mode differs, except for the position of the bucket, by the presence of certain forces in the lifting drive and the direction of its movement.

The analysis unit according to the signals of the rope length sensor and the handle stroke sensor determines the position of the bucket in space and the direction of its movement. Additionally, this analysis unit captures the value of the lift drive current. Thus, the location of the excavator bucket in the digging zone is determined, i.e. the anchor current of the lift drive exceeds 60% of the stop current with the corresponding readings of the rope length and handle stroke sensors. The coincidence of these conditions is defined as the beginning of the scooping mode.

When these conditions are met during the time T1 (T1 is the time delay of the reliability of the sign of the digging mode), the turn-off current of the turn drive is automatically limited to a value of 20-30% of the stop passport value, which provides a limitation of the torque of the turn engines, despite the turning motor turning the operator.

Deactivation of the automatic limitation of the electric drive signal of rotation occurs when any of the following conditions is met:

- the bucket handle is located in a space that extends beyond the zone limited by the vertical location of the handle and its perpendicular arrangement to the boom;

- the movement of the bucket in the direction of retraction of the handle during the time T2 (approximately 1.5 ± 2.0 s);

- the magnitude of the current drive lift when moving to lift the bucket corresponds to the condition I _p <0.6 I _stop for a time T3 (approximately 1.5 ± 2.0 s).

Figure 2 presents a block diagram of a device that allows you to implement a method of controlling the drive rotation of the excavator.

The device comprises a turn drive 1, a lift drive 2, a pressure drive 3, a turn command switch 4, a control unit 5, a signal analysis unit 6, a rope length sensor 7 and a handle length sensor 8.

The device operates as follows, figure 2:

- the signal analysis unit 6, using the signals of the rope length sensor 7, the handle 8 stroke length sensor and the lift drive current value 2, determines the position of the bucket in space and the direction of its movement, that is, the operation mode of the excavator. Additionally, the signal analysis unit 6 continuously records the value of the current of the lift drive 2. As soon as the signal analysis unit 6 determines that the excavator bucket is in the digging zone (position in zone I-II of FIG. 1), and the anchor current of the lift drive 3 exceeds 60% from locking, the coincidence of these conditions means the beginning of the scooping mode. Then, from the signal analysis unit 6, the control signal 5 receives a task signal to reduce the lock current of the turn drive 1 and, using the turn command knob 4, the armature current of the turn drive motor 1 is automatically limited to 20-30% of the lock current value.

In the proposed method and device:

- determination of the mode of scooping is made by the presence and direction of efforts in the rise and pressure, which makes it possible to provide the necessary accuracy of the auto-protection;

- a predetermined limitation of the value of the drive current of the rotation occurs when the stable conditions that determine the mode of digging and the range of protection are coincided.

Known technical solutions for controlling the electric drive of rotation are carried out on the basis of the analysis of one value - the current of the drive of rotation and its comparison with a control value. The current and voltage of the rotation drive are measured and the change in the moment of inertia and the load of the lift drive during scooping are not taken into account. Thus, the proposed method and device for its implementation has "significant differences" in comparison with the prototype.

The method for controlling the electric drive of turning a quarry excavator and the device for its implementation will automatically introduce a restriction in the operator’s actions during the mode of scooping with a high degree of reliability. This will increase the reliability of the working equipment of a career excavator (bucket, stick, boom) and increase its service life.

Information sources

1. Sadovnikov EM The choice of rational forms of static and mechanical characteristics of turning drives for mining excavators. Proceedings of the NIItyazhmash, Sverdlovsk, 1990, no. Increasing the resource and reliability of nodes of powerful excavators. S.35-39.

2. SU, copyright certificate 1461839, E02F 9/20, 07.15.86.

3. RU, patent 2107778, E02F 9/20, 1998.03.27.

Claims (2)

1. A method of controlling an electric drive turning a quarry excavator in scooping mode by limiting the current of the armature motor of the turning motor to a threshold value of the control signal equal to 20-30% of the stopping current value, characterized in that the state of the scooping mode is set according to the readings of the rope length sensors, handle stroke length, sensor drive lift and limit the amount of current armature motor turning automatically. 2. The device for implementing the method according to claim 1, containing rotation, lift, pressure and a rotation command gear connected to a control unit, characterized in that it contains a signal analysis unit to which a rope length sensor, a handle length sensor are connected , the anchor current sensor of the lift drive, and the signal analysis unit is connected to the control unit.

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