JP2004137854A - Driving device for paved road surface circular cutting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving device for a paved road surface circular cutting device capable of maintaining the proper number of revolutions and load torque for the change of specification of a cutting diameter in a wide scope and applicable without causing reduction in cutting efficiency. <P>SOLUTION: This driving device 1 for the paved road surface circular cutting device is constituted in such a way that a device 10, in which a plurality of expansible cutting beams 7 are connected with one end of an erected main shaft 6 and cutting edges 9 are attached to tips of the cutting beams 7, respectively, is provided, and the main shaft 6 is rotated and driven by an induction motor 21 to cut a paved road surface into a circular shape by the cutting edges 9. It is provided with a speed detector for detecting the speed of the induction motor 21, a slide frequency computing unit for determining a torque characteristic, a frequency computing unit for determining the frequency of an inverter 23, and a voltage computing unit. The induction motor 21 is driven by the variable frequency inverter 23 which uses computed outputs from the frequency computing unit and the voltage computing unit as a frequency command value and a voltage command value of the inverter 23, respectively. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a driving device for a pavement road surface circular cutting device that circularly cuts the periphery of a pavement road surface occupation object such as a manhole, and in particular, to cope with a wide-range specification change of a cutting diameter without reducing the cutting efficiency. The present invention relates to a driving device for a pavement road surface circular cutting device that drives an induction motor via a variable frequency inverter.
[0002]
[Prior art]
Conventionally, Japanese Patent Application Laid-Open Nos. 6-158612 and 2002-4215 disclose this type of circular cutting device. As a driving device for these cutting devices, a gasoline engine or an induction motor without rotation speed control or the like has been usually employed.
[0003]
However, since the size of the manhole varies depending on its type, if the cutting is performed at a constant rotational speed regardless of the cutting diameter, the cutting efficiency decreases as the size of the manhole increases, and the power consumption increases. There was a problem. There is also a problem that an excessive load is applied at the time of landing on concrete, so that a large-capacity motor is required.
[0004]
[Remarks]
In order to solve the above problems, the performance characteristics of this kind of circular cutting device were confirmed by experiments. In FIG. 8, a three-phase 200 V, 10 A, induction motor having a reduction ratio of 1/140 (hereinafter referred to as type 1), which is a driving device according to the present invention, is mounted, has a cutting diameter of 1000 mm, a rotation speed of 56 r / min, and And the experimental results when the load torque is changed by changing the cutting blade feed speed.
In the figure, the closed circles are plots of points measured by experiments. In addition, when the pressing force acting on the blade tip surface described later is small (for example, 100 kg or less), vibration occurred during operation due to insufficient pressing force, and the phenomenon of lifting of the gantry was observed. However, when the pressing force was increased to reach a certain predetermined value (for example, 120 kg), this phenomenon disappeared, the cutting noise became better, and the cutting could be performed smoothly.
It was also confirmed that the cutting speed increased in proportion to the pressing force when the rotation speed was constant. Note that the above pressing force is calculated from the value of the measured load torque by the following equation showing the relationship between the load torque and the pressing force.
T = μP D / 2 (1)
Here, T: load torque μ: friction coefficient between the cutting blade surface and concrete P: pressing force of the cutting blade in the vertical direction (total cutting blade surface)
D: Cutting diameter In the equation (1), if the pressing force P is fixed (150 kg) and the cutting diameter D is substituted, the load torque T for each cutting diameter can be calculated. Further, the higher the peripheral speed of the cutting blade, the higher the cutting speed. However, if the peripheral speed of the cutting blade is too high, it is not preferable in terms of safety from operation, power consumption, and life of the cutting blade.
Next, the relationship between the rotational speed N, the peripheral speed v, and the cutting diameter D is calculated by the following equation.
N = v × 60 / πD (2)
Therefore, from the above equations (1) and (2), in order to keep the equivalent work (T × N) proportional to the output constant, the pressing force P and the peripheral speed v should be constant. . From the above examination results, in this type of circular cutting device, in order to perform the most efficient driving in terms of performance characteristics, the peripheral speed is constant (for example, 3 to 5 m / sec) and the pressing force is constant. In this case, the load torque T proportional to the cutting diameter may be selected.
[0005]
FIG. 9 shows a characteristic curve of rotation speed: load torque created based on the above considerations. In the drawing, curves indicated by reference numerals 40, 41, and 42 are characteristic curves at peripheral speeds of 3, 4, and 5 m / sec, respectively. The rotational speed N is calculated from the above equation (2), and the load torque T is calculated from the above equation (1). In this figure, test data (marked with ●) at cutting diameters of 1000 mm, 1300 mm and 1500 mm are plotted. It can be understood that the tendency is almost the same near the curve 40.
[0006]
On the other hand, a driving device for a core drill according to the present application is disclosed in Japanese Patent No. 2783518. This is because the speed detector that detects the speed of the induction motor, the slip frequency calculator that determines the torque characteristics, the frequency calculator that determines the frequency of the inverter, and the number of gap magnetic fluxes created by the exciting inductance of the motor are always In a driving device for a core drill having a voltage calculator in which a constant V / f value is previously input into a circuit, a frequency of a maximum speed is set according to a use condition, and a bit bit is set for a wide bit size of the core drill. A frequency setter capable of coping with an appropriate peripheral speed of the surface is provided, and an adder is provided for adding the slip frequency calculated by the slip frequency calculation from the motor speed and the motor speed converted into the frequency, and an addition value from the adder is provided. The frequency of the highest speed set by the frequency setting device and the frequency calculator and configured to be input to the voltage calculator, A high-speed induction motor driven by a variable-frequency inverter having frequency output values of the inverter and frequency output values of the inverters as output values from the frequency operation device and the voltage operation device; and a speed reducer for the induction motor. It is a feature.
[0007]
[Problems to be solved by the invention]
The present invention has been proposed to solve the above problems. In other words, it is possible to maintain an appropriate number of revolutions and load torque for a wide range of specification changes in the cutting diameter, to cope with a reduction in cutting efficiency, and to withstand overload to reduce motor damage. It is an object of the present invention to provide a drive device for a pavement road surface circular cutting device which can be driven while maintaining a low current when grounded to a concrete surface.
[0008]
[Means for Solving the Problems]
According to the present invention, a plurality of extensible cutting beams are connected to one end of an upright spindle, and a feeder is provided in which a cutting blade is attached to each end of the cutting beams, and the spindle is rotationally driven by an induction motor. Then, in the drive device of the pavement road surface circular cutting device that cuts the pavement road surface circularly with the cutting blade, a speed detector that detects the speed of the induction motor, a slip frequency calculator that determines the torque characteristics, and a frequency of the inverter. A frequency calculator for determining the frequency, and a voltage calculator for which a V / f (applied voltage / frequency) value at which the number of gap magnetic fluxes created by the exciting inductance of the induction motor is always constant is previously input to the circuit. And a frequency setting device that can set the frequency of the maximum speed according to the usage conditions and can respond to the appropriate peripheral speed of the cutting blade surface for a wide range of cutting diameters of the pavement road surface circular cutting device. An adder is provided for adding the slip frequency calculated by the slip frequency calculator from the motor speed and the motor speed converted to the frequency, and the added value from the adder and the maximum speed set by the frequency setter. A variable frequency inverter configured to input a frequency to the frequency calculator and the voltage calculator, and using calculation outputs from the frequency calculator and the voltage calculator as a frequency command value and a voltage command value of the inverter, respectively. , And a high-speed rotation induction motor and its speed reducer.
[0009]
In the driving device of the pavement road surface circular cutting device configured as described above, the motor speed detected by the speed detector is input to the slip frequency calculator, and a torque characteristic similar to a desired series winding torque characteristic is obtained. The slip frequency is output as follows. Next, the slip frequency and the frequency conversion value of the motor speed are added in an adder, and input to a frequency calculator and a voltage calculator. If the added value is equal to or less than the set value of the frequency setting device at the highest speed, the value is kept as it is, and if it exceeds the set value, it is output as the set value. Then, the calculation outputs of the frequency calculator and the voltage calculator are input to the inverter as a frequency command value and a voltage command value of the inverter, and the inverter drives a high-speed rotation induction motor.
In this way, the appropriate rotation speed and load torque are maintained for the specification change of the cutting diameter, and it is possible to cope without reducing the cutting efficiency.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
First, an outline of a pavement road surface circular cutting device will be described. FIG. 1 is a front view showing the entire configuration of the pavement road surface circular cutting device.
In the figure, a driving device 1 of a pavement road surface circular cutting device is provided on a gantry 2 and includes a high-speed induction motor 21 with a speed reducer and a variable frequency inverter 23 for controlling the same. The main shaft 6, which is supported by the main shaft 6, is rotationally driven by the electric motor 21 through the speed reducer 5, and two extensible cutting beams 7 connected to one end of the main shaft 6 expand and contract with the increase and decrease of the cutting diameter. Let me. A feed device 8 is provided at the tip of each cutting beam 7, and a cutting blade 9 is attached to the feed device 8, and the cutting blade 9 sends the cutting blade 9 to a cutting surface via a feed driving device 10. In this way, the cutting is performed.
[0011]
FIG. 2 is a configuration block diagram showing an embodiment of the present invention. Reference numerals in the figure denote 20 a speed reducer, 21 a high-speed induction motor, 22 a speed detector, 23 an inverter, 24 a frequency calculator, 25 a voltage calculator, 26 a slip frequency calculator, 27 Denotes a frequency setting device having the highest speed, and 28 denotes an adder. VINV is an inverter voltage command value, FINV is an inverter frequency command value, VFM is the speed of the induction motor, VFS is the slip frequency, VFT is the maximum speed frequency determined by the use conditions, and VF0 is the frequency of the speed VFM of the induction motor. This is an added value of the converted value and the slip frequency VFS.
In such a configuration, the motor speed VFM is detected by the speed detector 22 from the induction motor 21 and is input to the slip frequency calculator 26 to output a slip frequency VFS having a desired torque characteristic. Next, the frequency conversion value VFM of the motor speed and the slip frequency VFS thereof are added by the adder 28 and input to the frequency calculator 24 and the voltage calculator 25.
On the other hand, the highest speed frequency VFT determined by the use conditions is set in the highest speed frequency setting device 27, and is input to the frequency calculator 24 and the voltage calculator 25, and the highest speed frequency VFT and the added value VFO are calculated. Output the inverter's frequency command value FINV and voltage command value VINV to the inverter 23, and the inverter drives the induction motor 21.
[0012]
3 and 4 are explanatory diagrams of the embodiment of the present invention. FIG. 3 is an equivalent circuit of an induction motor, where reference symbol r1 is a primary resistance, r2 is a primary converted secondary resistance, L1 is a primary leakage inductance, L2 is a primary converted secondary leakage inductance, L0 is an exciting inductance, S indicates slip, I1 indicates motor current, V1 indicates terminal voltage, f indicates frequency, and E2 indicates voltage applied to the secondary circuit.
FIG. 4 shows the torque characteristics of the induction motor 21 at each frequency. The torque characteristic curves denoted by reference numerals 30 to 33 are characteristic curves at respective frequencies when the number of magnetic fluxes generated by the exciting inductance is set to a V / f value that is always constant. The characteristic curve indicated by reference numeral 34 is a desired torque characteristic curve, that is, a torque characteristic curve similar to the series winding torque characteristic, intersects with the characteristic curves 30 to 33 at points 35 to 38, respectively, and the slip frequency at that time is Fs1 to fs4, respectively.
[0013]
2, the motor speed VFM is input to a slip frequency calculator 26. At this time, the slip frequency calculator 26 obtains a desired torque characteristic, that is, a torque characteristic similar to a series winding torque characteristic in FIG. The slip frequency VFS is output.
For example, in order for the speed VFM to be at the intersection 37, it is necessary to add and output only the slip frequency of fs3. Thus, the frequency conversion value of the speed VFM and the slip frequency VFS are added by the adder 28, and the added value VF0 is input to the frequency calculator 24 and the voltage calculator 25. Since the circuit of the frequency calculator 24 acts as a kind of limiter circuit, if the added value VF0 is equal to or lower than the highest speed frequency VFT set by the highest speed frequency setting unit 27, the frequency is passed as it is and the highest speed If it exceeds the frequency VFT, the frequency VFT of the highest speed is output as it is. The voltage command value VINV is set in advance so as to compensate for the voltage drop due to the primary impedance (r1 + jωL1) calculated from the primary resistance r1 and the primary leakage inductance L1 in FIG. 3 so that the torque does not decrease even at a low speed. The inverter command value is calculated based on the V / f value input to the voltage calculator 25.
Then, since the number of gap magnetic fluxes generated by the exciting inductance L0 is constant at any frequency, the torque does not decrease even at low speed. The calculated value is output to inverter 23 as voltage command value VINV. The inverter 23 drives the induction motor 21 by receiving the frequency command value FINV and the voltage command value VINV.
Since the above operation is performed continuously, a torque characteristic similar to the series winding torque characteristic in FIG. 4 is obtained. In the case of a high-speed (for example, 20,000 rpm) induction motor, this characteristic is matched to the load curve of the circular pavement cutting machine by using the high-speed region of the torque characteristic curve. The reason is considered to be that the exciting current cannot be sufficiently secured as in the case of a low speed.
[0014]
FIG. 5 shows a first embodiment of the present invention, in which the type 1 (three-phase 200 V, 10 A, reduction ratio 1/140) driving device has a torque, a rotational speed, an inlet current and an outlet (motor) at each rotational speed in the case of the driving device. 9 shows experimental data indicating a relationship between currents. In this figure, the solid line shows the characteristic curve, and the two-dot chain line 43 shows the condition that the inlet set current is 10 A and the outlet current is below the rated value, that is, the curve connecting the points where continuous operation is possible. As can be seen from the figure, the rotation speed can be kept constant irrespective of the change in the load torque. Further, it has a characteristic that it can be continuously operated even at a low speed (for example, 10 r / min), and can be operated without overloading the motor, such as when landing on concrete.
[0015]
FIG. 6 shows a second embodiment of the present invention, in which a driving device tested in the same manner as the type 1 described above: each rotation in the case of a three-phase 200 V, 15 A, and a reduction ratio of 1/70 (hereinafter referred to as type 2). FIG. 2 shows experimental data showing the relationship between torque, speed, inlet current and outlet (motor) current in numbers (drive is powered up). In the figure, the solid line indicates the characteristic curve and the two-dot chain line 44 indicates the result under the same conditions as the curve 43 in FIG.
[0016]
Next, FIG. 9 is a plot of the torque characteristic curves 43 and 44 shown in FIGS. 5 and 6 on FIG. 9 for the first and second embodiments of the present invention.
In FIG. 7, the torque lines of the cutting diameters 1500, 1300, 1000, 800, and 600 mm on the right side show the values of the load torque when the pressing force is constant (150 kg). For example, when the cutting diameter is 1000 mm shown in the figure, the rotation speed is 62 r / min (peripheral speed 3.3 m / sec) in the curve 43 of the first embodiment, and 110 r / min (circumferential speed) in the curve 44 of the second embodiment. 5.9 m / sec> can be achieved, and the pressing force of the cutting blade surface is always constant (that is, the surface pressure is constant) in any of the cutting diameters of 1500 to 600 mm. Wear is small, and the peripheral speed can be increased to about 3 to 6 m / sec by selecting the driving device type 1 or type 2, so that an increase in drilling speed can be expected.
[0017]
【The invention's effect】
The drive device of the pavement road surface circular cutting device of the present invention can maintain an appropriate rotation speed and load torque for a wide range of specification changes in the cutting diameter, can cope without a decrease in cutting efficiency, and can withstand overload. Thus, there is an effect that the motor can be driven while the damage to the motor is small and the current at the time of grounding is kept low. In addition, even if the cutting diameter changes, there is also an effect that continuous operation can be performed without changing the inlet set current.
[Brief description of the drawings]
FIG. 1 is a front view showing an overall arrangement of a pavement road surface circular cutting device.
FIG. 2 is a configuration block diagram showing an embodiment of the present invention.
FIG. 3 is an equivalent circuit diagram of an induction motor for describing an embodiment of the present invention.
FIG. 4 is a torque characteristic diagram at each frequency of the induction motor for describing the embodiment of the present invention.
FIG. 5 is a characteristic diagram showing a relationship among a rotation speed and load torque / input current / output current according to the first embodiment of the present invention.
FIG. 6 is a characteristic diagram showing a relationship among a rotational speed and load torque / input current / exit current according to a second embodiment of the present invention.
FIG. 7 is a characteristic diagram showing a relationship between a rotation speed, a load torque, and a cutting diameter according to the present invention.
FIG. 8 is experimental data showing the relationship between the pressing force of the cutting blade surface and the cutting speed.
FIG. 9 is a comparison diagram of the rotational speed and the load torque of the circular cutting device comparing the expected characteristic curve and the experimental data.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Drive device 2 ... Stand 5 ... Reduction gear 6 ... Main shaft 7 ... Cutting beam 8 ... Feeding device 9 ... Cutting blade 10 ... Feeding driving device 20 ..Speed reducer 21 high speed induction motor 22 speed detector 23 inverter 24 frequency calculator 25 voltage calculator 26 slip frequency calculator 27. · Frequency setting device 28 of maximum speed ··· Adders 30 to 33 ··· Torque characteristic curve 34 of each frequency ··· Desired torque characteristic curve 35 to 38 ··· Torque characteristic curve of each frequency and desired torque characteristic Intersections 40 to 42 with the curves: Torque characteristic curves 43, 44 ... Torque characteristic curves VINV of the first and second embodiments ... Inverter voltage command value FINV ... Inverter frequency command value VFM ... Induction motor speed VFS ... Slip The wave number VFT ··· highest rate of frequency VF0 ··· VFM + VFS
r1 Primary resistance r2 Secondary resistance L1 Primary leakage inductance L2 Secondary leakage inductance L0 of primary resistance Excitation inductance S Slip I1 Electric motor Current V1 Terminal voltage f Frequency E2 Voltage fs1 to fs4 applied to the secondary circuit Slip frequency

Claims (1)

A plurality of extendable cutting beams are connected to one end of the standing spindle, and feeders with cutting blades attached to the ends of the cutting beams are provided.The spindle is driven to rotate by an induction motor and the cutting blades are used. In a drive device of a pavement road surface circular cutting device that cuts a pavement road surface into a circle, a speed detector that detects a speed of an induction motor, a slip frequency calculator that determines a torque characteristic, and a frequency calculator that determines a frequency of an inverter. A voltage calculator in which a V / f value at which the number of gap magnetic fluxes generated by the excitation inductance of the induction motor is always constant is previously input into the circuit, and a frequency of a maximum speed is set according to use conditions. A frequency setting device is provided which can correspond to an appropriate peripheral speed of the cutting blade surface for a wide range of cutting diameters of a pavement road surface cutting device, and a slip frequency operation is performed based on the motor speed. An adder that adds the slip frequency calculated by the calculator and the motor speed converted to the frequency, and the added value from the adder and the frequency of the maximum speed set by the frequency setting device are referred to as the frequency calculator. And a high-speed rotation induction driven by a variable frequency inverter configured to input to the voltage calculator and to set the calculation outputs from the frequency calculator and the voltage calculator to a frequency command value and a voltage command value of the inverter, respectively. A drive device for a pavement road surface circular cutting device, comprising an electric motor and a speed reducer.

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