JP4037742B2 - Down the hole excavator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a down-the-hole excavator, and more particularly to a down-the-hole excavator driven by a pneumatic motor.
[0002]
[Prior art]
Conventionally, a method called a down-the-hole excavation method is known as an excavation method for excavating hard rock.
An excavator for performing the down-the-hole excavation method generally includes an air hammer device connected to the tip of a rod, a compressor for supplying compressed air for operating the air hammer device, and a hydraulic motor for rotating the rod. In addition, it is composed of a bit that excavates the ground by the synergistic action of the striking and rotation in response to the striking by the air hammer device and the rotation of the rod (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-5-287975 [0004]
[Problems to be solved by the invention]
However, such a conventional excavator requires two types of drive sources, a compressor and a hydraulic motor, which complicates and increases the cost of the drive system and secures installation space on steep slopes in the mountains. There was a problem that it was difficult to do.
As a method for solving such a problem, it is conceivable to use a pneumatic motor instead of a hydraulic motor. However, since air is a compressible fluid, a time lag occurs when the driving force is transmitted, and the rod It was difficult to maintain a stable operating state in response to a change in torque applied to the vehicle.
[0005]
The present invention has been made in view of the above-described problems of the prior art, and can simplify the drive system by unifying the drive source, and can immediately respond to changes in torque applied to the rod during driving. It is possible to provide a down-the-hole excavator capable of maintaining a stable operation state.
[0006]
[Means for Solving the Problems]
The invention according to claim 1 is an air hammer device connected to the tip of a rod, a compressor for supplying compressed air for operating the air hammer device, a rotary drive device for rotating the rod, and the air hammer A down-the-hole excavator provided with a bit for excavating the ground in response to the impact of the device and the rotation of the rod, wherein the rotational drive device comprises a pneumatic motor, and the pneumatic motor is supplied from the compressor to the air hammer device Driven by using a part of the compressed air, a detection means for detecting the rotational speed of the pneumatic motor or rod, a flow rate adjusting valve for adjusting the amount of air supplied to the pneumatic motor, and a pneumatic motor A pressure adjusting valve for adjusting the supplied air pressure, and a rotation speed detected by the detecting means within a predetermined range; About down-the-hole boring machine characterized by comprising comprises a feedback control means for adjusting the opening of the flow regulating valve and the pressure regulating valve to maintain a.
The invention according to claim 2 includes a plurality of the pneumatic motors, and further includes a flow rate equalization valve for equalizing the amount of air supplied to each pneumatic motor upstream of the pneumatic motors, and the feedback control means. 2. The down-the-hole according to claim 1, wherein the openings of the flow rate adjustment valve, the pressure adjustment valve, and the flow rate equalization valve are adjusted so as to maintain the rotational speed detected by the detection means within a predetermined range. Related to excavator.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of a down-the-hole excavator according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing an embodiment of a down-the-hole excavator according to the present invention.
The down-the-hole excavator according to the present invention includes a rod (2) suspended by a crane (1), an air hammer device (3) connected to the tip of the rod (2), and the air hammer device (3). Compressor (4) for supplying compressed air for actuating, rotation drive device (5) for rotating rod (2), striking by air hammer device (3) and rotation of rod (2) And a bit (6) for drilling. Since these basic configurations are the same as those of a conventionally known down-the-hole excavator, a detailed description thereof will be omitted.
[0008]
As the rotary drive device (5), a rotary table machine is used, and construction using such a rotary table machine is suitable in a narrow place such as a mountainous area where a pile driving machine does not enter.
FIG. 2 is a front view showing an example of a rotary table machine used as the rotary drive device (5), and FIG. 3 is a plan view thereof.
A boss (6) for inserting the rod (2) is provided at the center of the rotary table machine (5), and a pneumatic motor for rotating the rod (2) in the vicinity of the boss (6). (7) is provided with a total of two units, one on each side. Thus, the use of a pneumatic motor instead of a hydraulic motor as in the prior art as one of the motors (7) is one of the major features of the present invention, which makes it possible to unify the driving source.
[0009]
The down-the-hole excavator is usually required to generate a high torque at a low speed, that is, to have a high starting characteristic. Therefore, as the pneumatic motor (7), a piston-type pneumatic motor having a high flash rate is most preferably used.
Further, the number of pneumatic motors (7) is not particularly limited, but in the case of a large excavator, it is necessary to install a plurality of pneumatic motors.
[0010]
FIG. 4 is a block diagram showing the configuration of the down-the-hole excavator control system according to the present invention.
The piping connected to the compressed air discharge port from the compressor (4) was connected to the compressed air piping (8) for the air hammer connected to the air hammer device (3) and the two pneumatic motors (7). It branches off to the compressed air pipe (9) for control. Accordingly, in the present invention, a part of the compressed air that has been conventionally supplied from the compressor (4) to the air hammer device (3) can be used to drive the pneumatic motor (7). .
[0011]
The control compressed air pipe (9) includes a stop valve (10), a cooler (11) for maintaining the temperature of the compressed air at a predetermined value, and a pressure adjusting valve (13) through a filter (12) in this order. It is connected.
The pressure adjusting valve (13) is provided to adjust the pressure of the compressed air supplied to the pneumatic motor (7).
The pressure adjustment valve (13) is connected to the flow rate adjustment valve (16) through the pressure gauge (14) and the lubricator (15) in this order.
The flow rate adjusting valve (16) is provided to adjust the amount of air supplied to the pneumatic motor (7).
[0012]
The control compressed air pipe (9) passes through the flow rate adjusting valve (16), and then is branched in two directions by the branch pipe (17), one of which is connected to one of the pneumatic motors (through the flow equalizing valve (18)). 7), and the other is connected to the other pneumatic motor (7) which has a long pipe length and is far away.
The flow equalization valves (18) are provided to equalize the amount of air supplied to the two pneumatic motors (7), and the two pneumatic motors (7) are supplied with compressed air. Then, the rod (2) of the down-the-hole excavator is driven to rotate through the speed reducer (19).
The pneumatic motor (7) or the rod (2) is provided with detection means (not shown) for detecting the rotation speed. As the detecting means, for example, an encoder is used, but is not particularly limited.
[0013]
The opening of the pressure regulating valve (13), the flow regulating valve (16) and the flow equalizing valve (18) is automatically adjusted so that the rotational speed detected by the detecting means is maintained within a predetermined range. It is controlled so that the rod can be stably rotated even if the torque applied to the rod (2) fluctuates.
[0014]
The operation of the control system for the down-the-hole excavator according to the present invention will be described below after clarifying the characteristics of the pneumatic motor.
1. Performance Curve of Pneumatic Motor when Supply Air Pressure (Supply Air Pressure) is Constant FIG. 5 shows a performance curve of the pneumatic motor when supply air pressure is constant.
Pneumatic motors will have a shorter life if they are used at a rotational speed of more than _nm at the maximum output, and it will be difficult to stabilize if used at a speed lower than the low speed limit (n _l = approx. 0.2 _nm ). There is a recommended rotational speed range (approximately 0.2 to 1.0) _nm .
In addition, the number of rotations at which the same output can be obtained is at two locations on the low-speed side and the high-speed side centering on the maximum output rotation number, but if used on the low-speed side, air consumption can be saved.
Since the minima in terms of about 80% of the rotational speed n _m at an air consumption (air consumption Q / Output L) is the maximum output, rated speed the rotational speed of the point n _a ≒ 0.8n _m And
FIG. 5 shows the relationship between the torque T and the rotational speed n depending on the opening degree of the flow rate adjusting valve (16).
[0015]
2. When the supply air pressure is changed, the performance of the pneumatic motor changes. When the supply air pressure is changed, the torque, output, rotational speed, and air consumption are all linear (proportional) as the pressure increases. ) To increase.
[0016]
3. Relationship between Air Consumption and Rotational Speed in Pneumatic Motor Since the rotational speed is substantially proportional to the air consumption, the rotational speed is usually adjusted by adjusting the flow rate.
[0017]
The operation (control operation) of the control system for the down-the-hole excavator according to the present invention will be specifically described below based on the characteristics of the pneumatic motor described above.
1. When shifting from normal ground to soft ground When the tip (6) of the rod (2) hits the soft ground, the torque decreases from the rated operating state (1) as shown in FIG. Therefore, when the opening degree of the flow rate adjusting valve (16) is 10, the point (1) is moved to the point (2).
Here, if too increases the rotation speed, since the trouble such as the life cause a failure is shortened occur, lowering the rotational speed up to the rated rotational speed n _a as a 5 immediately stop the opening of flow control valve (16) as To. That is, the point (2) is moved to the point (3).
Then, when reaching the normal ground from the soft ground, the torque increases and the rotational speed decreases, so that the point moves from point (3) to point (4).
Here, the point ▲ 4 rpm of ▼ because smaller than the rated rotational speed n _a, to return to the point ▲ 1 ▼ by increasing again the flow rate adjusting valve the opening of (16) to 10,
Such a driving operation is automatically performed using the control system shown in FIG.
[0018]
2. When shifting from the normal ground to the rock, when the bit (6) at the tip of the rod (2) hits the rock from the normal ground, the torque increases, so that the opening of the flow control valve (16) is set to 10 Even if it is kept in this state, the number of revolutions is reduced. In the state of FIG. 5, the point ▲ 1 ▼ Once you reach color point ▲ 5 until ▼ speed slows limit rotational speed n _l, operating conditions results in a pulsating unstable. Therefore, in this case, it is necessary to increase the supply air pressure.
As described above, when the supply air pressure increases, any of torque, output, rotation speed, and air consumption increases linearly. Considering this, the supply air pressure is increased until the torque necessary for excavating the rock is reached.
FIG. 6 shows the relationship between torque and rotational speed when the supply air pressure is increased. Points (1) and (5) in the figure correspond to points (1) and (5) in FIG. ing.
As shown in the figure, when the supply air pressure is increased from P ₁ to P ₂ , the torque increases and moves from point (5) to point (6).
Then, Returning to the normal of the ground again, the torque is moved to the point ▲ 6 ▼ color point ▲ 7 ▼ to decrease, reduce the pressure from P ₂ to P _1, the point of FIG. 5 ▲ 1 to ▼ Try to bring it back.
Such a driving operation is automatically performed using the control system shown in FIG.
[0019]
3. When the rotation speed is always kept within the range of the recommended rotation speed, the relationship among the torque T ₁ , output L ₁ , air consumption Q ₁ and rotation speed n at the supply air pressure P = P ₁ is expressed as follows. .
T ₁ = a _T + b _T n... (1)
L ₁ = a _L n ² + b _L n + c _L (2)
Q ₁ = a _Q n + b _Q (3)
In addition, the relationship among the torque T ₂ , the output L ₂ , the air consumption Q ₂ and the rotation speed n at the supply air pressure P = P ₂ is expressed as follows.
(P ₂ / P ₁ ) = d _P (n / n _m ) + e _P (4)
(T ₂ / T ₁ ) = d _T (n / n _m ) + e _T (5)
(L ₂ / L ₁ ) = d _L (n / n _m ) + e _L (6)
(Q ₂ / Q ₁ ) = d _Q (n / n _m ) + e _Q (7)
[0020]
Next, if P = P ₁ can be expressed as shown in FIG.
At n = 0, T ₁ = T _m1
Since a _T 1 = 0 in the n = 2n _m, the equation (1),
a _T = T _m1 , b _T = −T _m1 / 2 _nm
In addition, when n = 0, L ₁ = 0
L ₁ = L _{m1 at} n = n _m
because it is _L 1 = 0 in the n = 2n _m, the equation (2),
a _L = −L _m1 / n _m ² , b _L = 2L _m1 / n _m , C _L = 0
∴T ₁ = T _m1 − (T _m1 / 2n _m ) n = T _m1 (1−n / 2n _m )
L ₁ = − (L _m1 / n _m ² ) n ² + (2L _m1 / n _m ) n = −L _m1 {(n / n _m ) ² −2 (n / n _m )} = − L _m1 (n / N _m ) {(n / n _m ) -2}
Q ₁ = a _Q n + b _Q
[0021]
That is,
(T ₁ / T _m1 ) = 1− (1/2) (n / n _m ) (8)
(L ₁ / L _m1 ) = (n / n _m ) {2- (n / n _m )} (9)
(Q ₁ / Q ₀₁ ) = (1/2) {(Q _m1 / Q ₀₁ ) −1} (n / n _m ) +1 (10)
Therefore,
(P ₂ / P ₁ ) = d _P (n / n _m ) + e _P (11)
(T ₂ / T ₁ ) = {d _T (n / n _m ) + e _T } / [T _m1 {1- (1/2) (n / n _m )}] (12)
(L ₂ / L ₁ ) = {d _L (n / n _m ) + e _L } / [L _m1 (n / n _m ) {2- (n / n _m )}] (13)
(Q ₂ / Q ₁ ) = 2 {d _Q (n / n _m ) + e _Q } / [Q ₀₁ {(Q _m1 / Q ₀₁ ) −1} (n / n _m ) +1] (14)
_{Here, d P, e P, n} m, d T, e T, T m1, d L, e L, L m1, d Q, e Q, Q 01, Q m1 is given by the specification of the air motor Constant (dimensional).
[0022]
In Expression (8) to Expression (14), P ₁ , P ₂ , T ₁ , T ₂ , L ₁ , L ₂ , Q ₁ , Q are set so that (n / n _m ) = 0.2-1 Select a value of ₂ .
In the case of a down-the-hole excavator, it is considered that first, the values of P ₁ and P ₂ are set, and then Q ₁ and Q ₂ are automatically controlled corresponding to the values of T ₁ and T ₂ .
However, the above formula is merely an example of a control method model.
[0023]
By performing the control operation using the feedback control as described above, it is possible to immediately cope with a change in torque applied to the rod during excavation work, and it is possible to maintain a stable operation state.
[0024]
【The invention's effect】
As described above, according to the first aspect of the present invention, since the two types of drive sources, the conventional hydraulic pressure and pneumatic pressure, can be unified, the drive system of the down-the-hole excavator can be simplified. The apparatus cost and the construction cost can be reduced, and the maintenance can be easily performed. In addition, since no hydraulic equipment is required and the installation space for the excavator is saved, excavation work on a steep slope in the mountain can be easily performed.
Further, the feedback control makes it possible to immediately respond to a change in torque applied to the rod during driving, and a stable operation state can be maintained.
According to the invention according to claim 2 , it becomes possible to control the output of a plurality of pneumatic motors in the same manner, and even a large excavator can immediately respond to a change in torque applied to the rod, and is stable. It is possible to maintain the operated state.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an embodiment of a down-the-hole excavator according to the present invention.
FIG. 2 is a front view showing an example of a rotary table machine used as a rotation driving device.
FIG. 3 is a plan view showing an example of a rotary table machine used as a rotation driving device.
FIG. 4 is a block diagram showing a configuration of a down-the-hole excavator control system according to the present invention.
FIG. 5 shows a performance curve of a pneumatic motor when supply air pressure is constant.
FIG. 6 is a diagram showing a relationship between torque and rotational speed when supply air pressure is increased.
FIG. 7 is a diagram showing a relationship between torque and rotational speed when supply air pressure is constant.
[Explanation of symbols]
2 Rod 3 Air hammer device 4 Compressor 5 Rotation drive device 7 Pneumatic motor 13 Pressure adjustment valve 16 Flow rate adjustment valve 18 Flow rate equalization valve

Claims (2)

An air hammer device connected to the tip of the rod, a compressor for supplying compressed air for operating the air hammer device, a rotary drive device for rotating the rod, and a blow and rotation of the rod by the air hammer device A down-the-hole excavator having a bit for receiving and excavating the ground, wherein the rotary drive device is composed of a pneumatic motor, and the pneumatic motor uses a part of the compressed air supplied from the compressor to the air hammer device. Detecting means for detecting the rotational speed of the pneumatic motor or rod, a flow rate adjusting valve for adjusting the amount of air supplied to the pneumatic motor, and adjusting the air pressure supplied to the pneumatic motor The pressure adjusting valve and the rotational speed detected by the detecting means so as to maintain within a predetermined range. Down-the-hole boring machine characterized by comprising comprises a feedback control means for adjusting the opening amount adjusting valve and the pressure regulating valve. A plurality of the pneumatic motors are provided, and a flow equalization valve for equalizing the amount of air supplied to each pneumatic motor is provided upstream of the pneumatic motors, and the feedback control means is detected by the detection means. 2. The down-the-hole excavator according to claim 1, wherein opening amounts of the flow rate adjustment valve, the pressure adjustment valve, and the flow rate equalization valve are adjusted so as to maintain the rotation speed within a predetermined range.

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