JPS622112B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic lowering control device for an excavator used in an excavator that excavates the ground with an excavator suspended on a suspension device via a wire rope or a cylinder.

In a machine that excavates the ground using a shaft excavator, such as a reverse circulation drill, the excavating tool is generally suspended by a wire rope wound around a winch, and the wire rope is lowered as the excavation progresses. When the drilling hole is deep and verticality is required, appropriate tension is applied to the wire rope and the drilling tool is suspended and held like a pendulum to prevent the Kerry bar from tilting. . Therefore, the winch operator must control the lowering operation of the excavator while constantly monitoring the tension of the wire rope. Manually maintaining the tension of this wire rope at a constant constant level requires consideration of various changes in the shaking ground, which is quite difficult and requires skill.

For this reason, JP-A-54-82803 and JP-A-54-118601 have been disclosed with the aim of automating this process. The former is to control the load on which the excavator is suspended to always be kept within a certain range regardless of the soil properties, and the latter is to control to always keep the excavation torque constant.

However, in the former case, what is being detected is only the load that suspends the excavation tool, that is, the load that is applied to the bit if you look at it from a different perspective. Therefore,
Keeping this bit load constant naturally means that the lowering speed of the excavator will be faster in soft ground and slower in hard ground. Blade-type bits are usually used when excavating soft ground, so when the descending speed of the excavator increases, the amount of biting into the cutter and the rotational speed of the bit increase, the excavation torque increases, and the bit rotation stops. Put it away. Therefore, if the excavating tool is lowered by detecting only the magnitude of the bit load, the bit rotation will have to be stopped and activated frequently, resulting in a disadvantage that the excavating work efficiency will be reduced.

In the latter case, if the ground is homogeneous, the excavation torque will not fluctuate very much, but if the ground is made up of alternating layers of gravel, soft and hard soil, or if hard soil is excavated using a roller bit, the excavation torque will vary. The fluctuations are very large, and depending on the conditions, the maximum value can reach 2 to 3 times the minimum value, making it practically impossible to control the excavation speed based on this value. . Therefore, if the excavator is lowered only by the excavation torque, it cannot be used to control hard ground excavation using the roller bit.

The present invention is a pit excavator that excavates the ground with a drilling tool suspended from a suspension device via a wire rope or a cylinder, and the bit is always used even if the soil conditions and the rotation speed of the bit change. It is an object of the present invention to provide an automatic lowering control device for an excavating tool that can automatically control the bit load and excavation torque so that appropriate bit loads and excavation torques are applied.

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 shows a pit excavator, which is constructed as follows. A winch 2 is installed at the rear of the main body 1, and a leader 3 is installed at the center. A control device 4 including a hydraulic pump for driving the winch 2 and the excavating tool is installed between the winch 2 and the leader 3, and a rotary table 5 for driving the excavating tool is engaged at the front of the leader 3. The drive reaction force of the rotary table 5 can be taken by the main body 1.

An excavating tool having the following configuration is suspended from a wire rope 11 that is let out from the winch 2 and passed through a sheave block at the top of the leader 3. The excavation tool includes a kelly bar 6 that is vertically movably engaged with the rotary table 5 and receives a driving torque, a drill pipe 8 that is sequentially connected to the lower end of the kelly bar 6, and a drill pipe 8 that is connected to the lower end of the drill pipe 8 to remove earth and sand. When the bit 7 to be excavated and the earth and sand excavated by the bit 7 are sucked up together with water and discharged to the ground through the inside of the bit 7, the drill pipe 8 and the Kelly bar 6, the upper end of the Kelly bar 6 and a non-rotating body are used. The suction hose 9 and a swivel joint 10 are interposed between the suction hose 9 and the suction hose 9. One end of the wire rope 11 is connected to a load cell 12 which is attached at one end to the upper part of the leader 3, for example to a top sheave block. Furthermore, wheels 14 that roll on rails 13 laid on the ground are provided at the bottom of the main body 1.

FIG. 2 shows an automatic lowering control device for an excavator according to the present invention. Each port of the electrohydraulic servo valve 15 is connected to a hydraulic pump 17 that pumps oil from an oil tank 16.
The output shaft of the hydraulic motor 18 is connected to the drum 2' via a speed reducer 19. The servo valve 15 is configured to be able to gradually switch its spool by a function generator 20 connected to the load cell 12 and to select ports U and D thereof. 22 is a relief valve that controls the driving pressure of the automatic descent control circuit.
Note that, in practice, it is convenient to configure the winch 2 so that it can be hoisted and lowered manually as well.

Further, the bit 7 engages with the rotary table 5 via the kely bar 6 and is rotated by the driving torque of the rotary table 5. Next, the configuration of this drive device will be explained. Oil in the oil tank 16 is pumped by a hydraulic pump 23 to drive a hydraulic motor 24. The output shaft of the hydraulic motor 24 is connected to a drive shaft of a gear group 25 of a reduction gear. Finally, the rotary table 5 is rotated. 26 is a relief valve that limits the driving pressure of the hydraulic motor 24. 27 is a pressure converter that detects the pressure on the inlet side of the hydraulic motor 24 and converts the magnitude of the pressure into voltage. This includes a filter 42 that cuts off temporary high voltage due to surge pressure.
A comparator 30 is connected to compare the detected amount with a preset voltage value and operate timers 28A, 28B and relays 29A, 29B, and relay 29A is connected to electromagnetic switching valves 50, 51.
A contact is connected to the excitation part that selects ports X and Y of the servo valve 15, and is connected to the servo valve 15 when the excitation part is excited. It has been incorporated. Timer 28A continues to be energized for a set period of time even when relay 29A is deactivated by the voltage selected by comparator 30. In other words,
When the excavation torque fluctuates widely, even if the voltage that operates the drum 2' is removed, it disappears instantly.
This is also to prevent the flapping phenomenon in which the drum 2' is repeatedly discarded instantaneously without being able to operate the drum 2'. Similarly, the timer 28B is energized when the relay 29B is activated, and once it is energized, it continues to be energized for the set time even if the relay 29B stops operating.
Since the contact 8B is inserted into the circuit of the function generator 20 as a B contact, this circuit is cut off, and the servo valve 15 is held at the neutral position shown during the above set time.

The function generator 20 is capable of obtaining an electro-hydraulic servo input as shown in FIG. . Therefore, the spool of the servo valve 15 can be gradually moved in any pattern, so that the lifting speed of the excavator can be gradually increased or decreased.

FIG. 4 shows the operating range of the comparator 30 based on the output voltage when the driving oil pressure of the hydraulic motor 24 is captured as a voltage by the pressure converter 27, and the voltage ranges from E _E to E _F
The relay 29A is operated in the range ED to EE, the relay 29B is operated in the range _ED to _EE , and neither relay is operated in the range O to _ED .

Figure 5 shows an example of an operation panel, which includes a power switch/rope number changer 31 that can change the electrical resistance and change the number of ropes for hanging the excavation tool, and a load indicator. 32 and the voltage value E
Voltage regulators 33, 34, 35, 36 for setting _A , E _B , E _D , E _E respectively, and voltage values E _A , E _B , E
Voltage indicators 37, 3 indicating _D and E _E respectively
8, 39, 40, and a pressure indicator 41 that displays the pressure on the inlet side of the hydraulic motor 24.
Furthermore, the control pattern shown in FIG. 3 can be selected, with 52 being a control pattern, 53, 54,
55 is an operation button for selecting each pattern of the function generator 20, respectively.

Now, regardless of the control device of the present invention, Kerryba 6,
When the drilling tool consisting of the bit 7, drill pipe 8, and swivel joint 10 is hoisted up, the load indicator 3
2 displays the sum of the entire weight. Next, when the control device of the present invention is activated, the voltage value detected by the load cell 12 in the above state is set to the maximum E.
_C , the servo valve 15 is controlled by the function generator 20.
The spool is switched to the state shown in FIG.
etc. to descend. When the bit 7 reaches the bottom of the hole, the tension in the wire rope 11 decreases, and the output voltage of the load cell 12 reaches the values E _A to E _B in FIG. When the value becomes zero, the servo valve 15 becomes neutral, and the drum 2' stops.

When the rotary table 5 is driven, the bit 7 rotates and excavates. As the excavation progresses, the tension of the wire rope 11 increases and when the output voltage of the load cell 12 exceeds E _B , the drum 2' rotates again and the bit 7 and the like fall. Furthermore, if the wire rope 11 becomes loose due to oil leakage from the hydraulic motor 18, and the output voltage of the load cell 12 drops below E _A , the servo input becomes negative by the function generator 20. , the spool of the servo valve 15 is switched to the U state. As a result, the pressure oil flows as shown by the dashed arrow, the drum 2' is rotated in the opposite direction, and the bit 7 is rotated in the opposite direction.
etc. are rolled up. When controlling based on the bit load element, this hoisting control can be omitted and control in two stages, stopping and hoisting, can be sufficient for actual work.

On the other hand, a change in excavation torque causes a change in the pressure of the hydraulic motor 24, so by reading the value of the pressure indicator 41 that displays this pressure, it is possible to know the state of change in the excavation torque. Furthermore, from the frequency of this change, it is also possible to know from this indicator 41 the state of the ground currently being excavated, ie, whether the excavation is in a gravel layer or homogeneous ground. Then we entered very hard ground and bit 7
The maximum voltage value E _F detected by the pressure transducer 27 when the rotation of the
Therefore, it is in the range of F in Fig. 4, and comparator 3
0 activates the relay 29A, energizes the timer 28A, and for the set time of the timer 28A, the spools of the electromagnetic switching valves 50 and 51 are switched to the X and Y states, respectively, and the control circuit by the load cell 12 is activated by the timer. Since the contact point 28A is cut off, the load cell 12 is no longer controlled, and the spool of the servo valve 15 is placed in the neutral position. Therefore, the pressure oil from the hydraulic pump 11 flows as indicated by the dashed arrow, and the drum 2' rotates in the winding direction, raising the bit 7 and the like. When the bit 7 rises, the engagement between the bit 7 and the earth and sand at the bottom of the hole is released, so the bit 7 becomes rotatable and the excavation torque at this time also becomes smaller. Therefore, timer 28
After the set time A has elapsed, if neither relay 29A or 29B is operating, the electromagnetic switching valves 50 and 5
The signal to operate each spool of 1 is no longer output, and after this, the function generator 2 by the load cell 12
According to the operating state of 0, the spool of the servo valve 15 operates.

Next, when the bit 7 does not stop rotating but enters a fairly severe digging condition, the voltage value detected by the pressure transducer 27 becomes E _D ~
When the value of E _E is reached, the comparator 30 activates the relay 29B, energizes the timer 28B, and interrupts the circuit that energizes the spool of the servo valve 15 for the set time of the timer 28B, so that bit 7, etc. stop.

Next, when bit 7 is being excavated with a light load, the voltage value detected by the pressure transducer 27 becomes a value between O and E _D , and the comparator 30
Since both 9A and 29B are not operated, no signal is output to operate the spools of the electromagnetic switching valves 50 and 51, and the drum 2' is rotated only by the output voltage factor of the load meter 12.

As mentioned above, to summarize the control based on the elements of digging torque, if a digging torque that stops the rotation of bit 7 occurs even temporarily, bit 7 etc. can be hoisted up and bit 7 can be rotated. Let it be. In addition, although Bit 7 does not stop rotating, if a drilling torque that is likely to stop occurs,
The load on bit 7 is reduced by stopping the lowering (including winding) operation of bit 7 and the like. In addition, in the case of light torque, it is designed not to be involved in the hoisting and lowering operations of the bit 7 and the like. That is, the hoisting and lowering of the drum 2' is controlled mainly by the bit load, and when the excavation state of the bit 7 cannot be detected by the bit load, the excavation torque is used to stop the excavation state. Therefore,
The lowering control of bit 7 and the like using the excavation torque is not incorporated into this control circuit.

In normal excavation, the relay 29B is activated before the rotation of the bit 7 is stopped, so unless the excavation condition causes a considerable fluctuation in the excavation torque, that is, the condition in which the relay 29A is activated. , Bit 7, etc., are rarely forced to rise because the downward movement of Bit 7, etc. is stopped. If the bit 7 stops rotating and the drum 2' starts winding up the bit 7, etc., this will reduce excavation efficiency, so the voltage is detected in the range of voltage values E _D to _{E E.}
Controlling the operation of the drum 2' has a great effect on increasing excavation efficiency.

When excavating with a blade type bit in soft ground, the bit load is small and does not reach the control value, but the amount of biting by the cutter increases or the rotation of bit 7 stops due to insufficient driving torque. It may happen that you do. In such a case, the conventional control device using the bit load could not control the drilling unless the bit load reached the control value, but the control device of the present invention incorporates a circuit that constantly monitors the excavation torque. Therefore, even if the bit load is small and a signal is issued to switch the spool of the servo valve 15 to state D, when the excavation torque reaches the controlled value, the timer 28B is activated by the relay 29B. The contact opens, the hydraulic circuit to the drum 2' is closed, and the rotation of the drum 2' stops, so the cutter no longer bites, the load on bit 7 is reduced, and the rotation of bit 7 is prevented from stopping. be able to.

Next, in contrast to the current control device, which detects only the magnitude of excavation torque and lowers the excavation tool, when using a roller bit or a stratum with large fluctuations in excavation torque, the excavation tool must be raised and lowered frequently. However, by adopting the control device of the present invention, the bit load, which has a smaller fluctuation range than the excavation torque fluctuation range, is mainly controlled, so a stable descending speed could not be obtained. Excavation can be done. In addition, with conventional excavation torque control, it was not possible to give the optimum bit load, which caused problems, especially in the case of roller bits, but with the present invention, it has become possible to control directly with the bit load, so it is possible to achieve the optimum bit load. The bit load can be selected arbitrarily, increasing the life of the cutter. Furthermore, in addition to the optimum bit load, if the load torque on bit 7 becomes large, excavation will no longer be possible automatically, so in addition to controlling just the bit load, excavation torque is also controlled, so the bit diameter and Depending on soil conditions, control using excavation torque is also possible, allowing for a wide range of options.

In this way, the digging tool is always held within a certain range of rope tension and digging can continue automatically.

Further, a similar operation can be obtained by using a hydraulic cylinder instead of a winch using a wire rope. Further, the output signal of the load cell may be hydraulic or mechanical (using a cam).

Among the above embodiments, the load indicator 32 on the operation panel
This will be explained in detail using FIG. Load indicator 3
2 consists of the following parts. That is, a load indicating pointer 43 located in the center, a movable groove 44 of the pointer 43, a scale board located on the right side of the groove 44 and indicating the crane lifting load, and a scale board indicating the voltage generated in the load cell 12 are written together. Nameplate 45, nameplate 45
Voltage indicating pointer 46, pointer 46 located on the right side of
a movable groove 47 located on the left side of the movable groove 44;
It also includes a movable name plate 48 whose load scale is shown in reverse relative to the name plate 45, and a dial 49 for moving the movable name plate 48.

Next, the adjustment method will be explained. First, when the excavating tool consisting of the Kelly bar 6, the bit 7, the drill pipe 8, and the swivel joint 10 is hoisted without using the control device of the present invention, and the number of ropes to be hung is, for example, 6, the number of ropes to be hooked is switched. 31 is set to "6", the movable amount is automatically calculated to be six times the voltage value detected by the load meter 12, and the pointer indicates the corresponding load value. This pointer position is the load 15t shown by the two-dot chain line in FIG. Then, turn the dial 49 to move the movable name plate 48 to adjust the zero position of the scale plate at this position. Next, the bit 7 is gradually deposited on the bottom of the hole, and the deposited load is increased until the pointer 43 points to the bit load to be controlled. Stop placing the bit 7 etc. on the bottom of the hole at the position pointing to the control load corresponding to the load cell output voltage E _A , and set the pointer 46 which is the load cell voltage value E _A at that time.
Read the value indicated by and turn the voltage regulator 33 to adjust the value of the voltage indicator 37 to the value indicated by the pointer 46. Next, further deposit bit 7 etc. on the hole bottom, stop depositing bit 7 etc. on the hole bottom at the position pointing to the control load corresponding to the load cell output voltage E _B , and check the voltage value E of the load cell at that time. _B , read the value indicated by the pointer 46, and adjust the voltage regulator 3.
4 to adjust the value of the voltage indicator 38 to the value indicated by the pointer 46. This load indicator 3
2 can read not only the instruction of the lifting load of the crane, but also the bit load, and also the voltage value when determining the control voltage.

Now that the control load has been set, all that is left is to instruct automatic descent and excavation can be performed under the control described above.

As described above, according to the present invention, a control circuit is provided to control the lowering of the suspension device according to the suspended load of the excavation tool, so that the detected load is always within the set range, and it is also possible to prevent the excavation torque from becoming excessive. Since a control circuit is provided that sometimes stops or hoists the suspension device depending on the detected amount of excavation torque, the following effects can be obtained.

(1) Rather than simply lowering the excavation tool based on the bit load, we also added a control that constantly limits the excavation torque, making it easier to use when excavating with a blade-type bit, especially in soft ground. In this case, it is possible to obtain an excavation speed that matches the biting depth of the cutter and the rotational speed of the bit, thereby eliminating the frequent repetition of stopping and operating the rotation of the bit, thereby increasing the efficiency of excavation work.

(2) The excavation tool is not lowered only by the excavation torque, but rather is mainly controlled by the bit load, so it is possible to perform more stable excavation compared to excavation torque control, and depending on the excavation conditions. Regulations based on excavation torque are automatically added, providing a wide range of support.

(3) Since the holding force of drilling tools such as bits can be automatically controlled within an arbitrary fixed range, the vertical accuracy of the drilling hole can be maintained.

(4) Operators do not have to constantly monitor the excavation status, which saves labor.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a reverse circulation drill according to the present invention, FIG. 2 is a system diagram showing an embodiment of an automatic lowering control device for a drilling tool according to the present invention, and FIG. 3 is a side view showing a reverse circulation drill according to the present invention. Figure 4 showing the output diagram of the function generator operated by the output voltage of the load cell.
The figure shows the operating range of the comparator operated by the output voltage of the pressure gauge in Figure 2, Figure 5 is an explanatory diagram of the operation panel corresponding to the control device in Figure 2, and Figure 6 is the one shown in Figure 5. It is an enlarged detailed view of a load indicator on the operation panel. 1...Excavator main body, 2...Winch, 2'...
Drum, 3... Leader, 5... Rotary table, 6... Kelly bar, 7... Bit, 8... Drill pipe, 10... Swivel joint, 11...
... Wire rope, 12 ... Load cell, 15 ... Electro-hydraulic servo valve, 17, 23 ... Hydraulic pump, 1
8, 24...hydraulic motor, 20...function generator,
27...Pressure transducer, 28A, 28B...Timer, 29A, 29B...Relay, 30...Comparator, 50, 51...Solenoid switching valve.

Claims (1)

[Claims] 1. A vertical hole excavator that excavates the ground with a drilling tool suspended on a suspension device via a wire rope or a cylinder, comprising a suspended load control device for the drilling tool and an excavation torque control device for the drilling tool. , and the suspended load control device includes a load cell that detects the suspended load of the excavation tool, and a function that provides an input signal to an electro-hydraulic servo valve that operates the suspension device of the excavation tool in response to the output voltage of the load cell. The excavation torque control device includes a pressure converter that detects the pressure on the inlet side of the hydraulic motor that drives the excavation tool and converts it into a voltage value, and a pressure converter that detects the pressure on the inlet side of the hydraulic motor that drives the excavation tool and converts it into a voltage value, and a a comparator that compares the detected value detected by the pressure transducer with a preset value via the cutting filter; and an electromagnetic switching valve that stops or hoists the suspension system of the excavating tool based on the output of the comparator. a timer and a relay to operate the signal from the function generator so as to automatically control the suspension system of the excavating tool into at least two categories, stop and hoist, according to the signal from the load cell. When the excavation torque is input to the servo valve and becomes excessive, the signal from the load cell to the function generator is cut off, the signal is separated by the comparator according to the detected amount of excavation torque, and the excavation tool is suspended. An automatic lowering control device for an excavating tool, characterized in that an input is made to an electromagnetic switching valve for stopping or hoisting the device.