JPS6329079B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a depth detection device that is attached to a pit excavator such as an earth drill or a bucket-type continuous wall machine in which the excavation tool is supported by a wire rope.

For earth drills and bucket type wall machines,
In order to make this repetitive work easier, since a pit is excavated by repeatedly taking earth and sand into a bucket, pulling it up to the ground, and discharging it,
As shown for the earth drill in FIG. 1, a system is adopted in which a bucket 3 is supported by a crane 1 with a wire rope 2. The bucket 3 is attached to the lower end of the Kelly bar 4, and the Kelly bar 4 is connected to the Kelly bar drive device 6 installed on the front frame 5.
The upper end is connected to the wire rope 2 via a swivel joint 7, and the Kelly bar 4 and the bucket 3 (i.e., excavation tool) are connected by operating the Kelly bar drive device 6.
is now being rotated. Further, the wire rope 2 is hung on a sheave 9 at the upper end of the boom 8, and is repeatedly retracted by a winch 10 to raise and lower the bucket 3.

In such a pit excavator, the lowering of the bucket is controlled by the brake of the winch 10 so as to reduce the time required for vertical movement of the bucket to take in and discharge soil into the bucket 3. This is often done by a so-called free-haul operation in which the excavator is released and the clutch is released to release the power transmission and the excavator is lowered by its own weight. However, when lowering the bucket through this free hole operation, if the free hole operation was performed continuously until the bucket reached the bottom 11a of the hole 11, the bucket would violently collide with the bottom 11a of the hole, damaging the drilling tool. There is a risk of causing Therefore, conventionally, a depth indicator that displays the depth of the drilling tool is installed in the operator's cab, and the operator knows the depth of the drilling tool by looking at the value displayed on the depth indicator, and the operator knows the depth of the drilling tool by checking the value displayed on the depth indicator. When approaching, the brakes are applied to prevent the drilling tool from colliding violently with the bottom of the hole.

Of these depth detection devices for pit excavators,
In non-contact position detection devices such as proximity switches, the proximity body that activates the switch is attached to the sheave that guides the wire rope for hanging excavation equipment, whereas the bracket to which the switch is attached is attached to the non-rotating part. Since the switch is mounted on a screw seat provided in the switch, it is difficult to determine the relative position of the switch and the nearby object, especially when a switch is used to determine the direction of rotation or when many switches are installed to improve accuracy. It was time consuming. Furthermore, if the bolt that fixes the bracket to the non-rotating part becomes loose, the relative position between the switch and the nearby object may become incorrect, and if the bolt falls off, the bracket will fall off along with it, causing the sheave to become loose. This caused damage to the detection device, making it difficult to reuse it.

In view of the above-mentioned drawbacks, the present invention provides a vertical hole excavator having means for detecting the amount of movement and the direction of movement, which makes it easy to position the bracket to which the switch of the non-contact position detection device is attached, and is configured to prevent measurement errors and damage. The purpose of the present invention is to provide a depth detection device.

To achieve this object, the present invention provides a depth detection device for a pit excavator in which a drilling tool is supported by a wire rope. A bracket to which a switch which is operated by the proximity of a nearby object or a permanent magnet is fixed is mounted so that the swinging fulcrum is at the center of the rotating shaft of the sheave, and a fixing means for suppressing the swinging of the bracket is provided. It is characterized by the fact that it is provided.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 2 shows the overall configuration of the detection device including the depth display device, 13 is a movement amount detector for detecting the amount of movement of the wire rope 2, and 14 is a movement amount detector for detecting whether the wire rope 2 is being paid out or not. A moving direction detector 15 is a discrimination circuit that receives a signal from the moving direction detector 14 and determines whether the wire rope 2 is let out or retracted. 16 is a calculation device that calculates the depth of the excavation tool; 3
Reference numeral 1 denotes a unit length setting device constituted by a digital switch that can arbitrarily set the amount of movement of the wire rope 2 per pulse interval of the movement amount detector 13; 13
The depth of the excavating tool is calculated by receiving an on/off type digital signal from the excavator, a signal from the discrimination circuit 15, and a signal from the unit length setting device 31. 20 is a reset button for setting the value of the calculation device 16 to zero in order to clarify the depth measurement reference point.

The indicator for displaying the depth of the excavation tool may be provided with either a digital indicator or an analog indicator, but in this embodiment, a digital indicator that receives a signal from the calculation device 16 and displays a numerical value is used. Total 17
and a digital-to-analog converter 1 that converts the digital signal from the arithmetic unit 16 into an analog signal.
8 and an analog display 19 that receives an analog signal from the digital-to-analog converter 18 and displays the depth.Depth can be recognized by the analog display 19 during free hole, and when the excavation tool is stationary, the digital An indicator 17 allows accurate depth reading.

In addition, in this embodiment, in order to reduce the burden on the operator in recognizing the depth of the drilling tool during freehole, the brake operation is performed when the brake operation is required, that is, just before the drilling tool reaches the bottom of the hole, or when the When using a type kelly bar, a device 25 is provided which issues an alarm immediately before each stage kelly bar is fully extended and the retaining protrusions collide with each other, or immediately before the outermost kelly bar (outer kelly bar) collides with the upper part of the kelly bar drive device. ing.

To explain the device 25 for issuing the alarm, 32a, 32b, and 32c are depth setters for setting arbitrary depths such as the depth of the hole bottom and the unit Kelly bar length, and 33a, 33b, and 33c are the depth setters 32a, Comparators 34a, 34b, and 34c receive signals from each comparator and compare whether the depth has become shallower by an appropriate depth l set in consideration of brake operation than the depth L set by 32b and 32c. When the depth of L-l) is reached, the lamps 35a, 35b, 3 corresponding to each depth are turned on.
In addition to instructing to blink 5c and sounding the buzzer 36, the buzzer/lamp instructs to turn on the lamps 35a, 35b, and 35c corresponding to each depth when the depth reaches L, and instructs to stop the buzzer 36. This is a drive circuit.

Therefore, the feature of the present invention is the configuration regarding the movement amount detector 13 and the movement direction detector 14, and in this embodiment, the switches 13a, 13b and 14a, which constitute these detectors 13, 14,
The case where 14b is a switch operated by a permanent magnet will be explained. As shown in FIGS. 1, 3, and 4, near the outer periphery of the sheave 9 at the tip of the boom 8 on which the wire rope 2 is hung, a plurality of permanent magnets 24 are provided at equal intervals in the circumferential direction. The bracket 40 to which the switches 13a, 13b and 14a, 14b are fixed is attached to the rotating shaft 37 of the sheave 9.
A part of the bracket 40 is fixed to a screw seat 38 welded to the boom 8 with a bolt 39.

With such a switch mounting structure, the gaps between these switches and the permanent magnet 24 are inevitably fixed, making it difficult for assembly errors to occur and positioning to be easy, making installation easier. be done. Moreover, even if the bolt 39 fixing the bracket 40 becomes loose, the bracket 40 will not be attached to the rotating shaft 37.
Since there is a swinging fulcrum, there is no deviation in the gap between the permanent magnet 24 and the switches 13a, 13b, 14a, 14b and the relative position of each of these switches, and there is no problem with depth detection, and there is no possibility of the switch falling off. It will not be damaged and become unusable.

Note that as in this embodiment, the outer diameter of the ring 50 is
By making the sheave 9 or the sheave 9' attached coaxially with the sheave 9' to be equal to or smaller than the sheave 9, there is no need to modify the retainer 41 of the rope hanging thereto into a special shape.

Furthermore, in this embodiment, the permanent magnet 24 is embedded in a ring 50 made of magnetic material, and the permanent magnet is used to operate the switch. In order to prevent this from occurring, the permanent magnets 24 can be installed close together, and the switch opening/closing response speed by the permanent magnets 24 is fast, and a response of up to 1000 CPS is possible, so a detection device with high detection accuracy can be used. realizable. Further, in this embodiment, in order to obtain higher detection accuracy, permanent magnets 24 are arranged in two rows on the outer periphery of a ring 50 provided on one side of the sheave 9. Note that one row of permanent magnets may be arranged on each side of the sheave 9.
Furthermore, although the mounting intervals of the permanent magnets 24 in the same row are equal, the mounting intervals of the permanent magnets in different rows are relatively shifted by half a pitch to prevent mutual interference between the permanent magnets in different rows. The switches 13a and 13b for detecting the amount of movement are arranged in different columns, and the switches 13a and 13b are arranged in one column.
When the switch 13 is on one permanent magnet 24,
b, 13a are attached to the bracket 40 so as to be located between the two permanent magnets in the other row. Therefore, as shown in FIG.
The switches 13a and 13b are operated alternately by wrapping the operating time _T1 .
The total number of pulses obtained by the operation with b becomes a signal indicating the amount of movement of the wire rope.

On the other hand, the switches 14a and 14b constituting the moving direction detector 14 are mounted on the bracket 40 so that one of them operates earlier than the other depending on the direction of rotation of the sheave 9. That is, when the sheave 9 rotates clockwise (wire rope payout direction) in FIG. 3, one switch 14 is turned off as shown in FIG. 6A.
The other switch 14b operates with a delay in response to the operation of switch a, and after a time lapse of _T2 , switch 14a
operation stops. When the sheave 9 rotates in the counterclockwise direction (wire rope retracting direction) in FIG. 3, switch 1 is turned
The switch 14a is activated with a delay with respect to the activation of the switch 4b, and after a time lapse of _T2 , the operation of the switch 14b is stopped. In this way, the switches 14a, 1
The moving direction of the wire rope is determined depending on which of the wire ropes 4b is activated first. Therefore, the discrimination circuit determines whether the operations of the switches 14a and 14b overlap in time, compares which switch operates faster, and changes the output signal based on the comparison result. There is.

Further, as shown in FIG. 7, the arithmetic device 16 is composed of an integrating circuit 16a and an arithmetic circuit 16b, and when the output signal of the discriminating circuit 15 indicates wire rope payout, the integrating circuit 16a detects the movement amount detector 13 Each time a pulse is applied, 1 is added to the value stored up to that point; on the other hand, when the output signal of the discrimination circuit 15 represents wire rope renormalization, the value is added every time a pulse is applied. It is configured to perform an operation of subtracting 1. Note that this incorporates a pulse chattering prevention circuit with a large time constant. The calculation circuit 16b receives the value of the wire rope movement amount S per pulse set by the unit length setting device 31 and performs calculation to convert the value of the integration circuit 16a into the depth of the excavation tool. The depth L is calculated using the following formula.

L=p×n×s/m where p: Amount of pulse generation per revolution of the sheave 9 n: Amount of rotation of the sheave 9 s: Amount of wire rope movement per one pulse s=πD/p [D: Amount of the sheave 9 Pitch circle (see Figure 3)] m: Wire rope multiplier The digital display 17 and analog display 19, which display the calculated value, indicate the wire rope feeding direction with respect to the zero scale position. one,
The renormalization direction is displayed as a + sign.
Normally, the setting is zero when the excavation tool 3 such as a bucket is located on the ground surface, so the depth of the excavation hole is displayed as -, and the height when the excavation tool is lifted above the ground is displayed as +. Therefore, the display range of the analog display meter 19 is wider for - than for +.

As shown in FIG. 8, the digital display meter 17 and the analog display meter 19 are installed on the same panel surface of one case 21, and the case 21
It is installed in the instrument panel of the driver's cab as shown at 30 in the figure. The case 21 also includes a power on switch 22.
, the power lamp 23, and the reset button 2.
0, depth setters 32a, 32b, 32c, lamps 35a, 35b, 35c, and a buzzer 36 are attached, and the arithmetic unit 16, the discrimination circuit 15,
Digital-analog converter 18, unit length setter 31, comparators 33a, 33b, 33
c. Buzzer/lamp drive circuit 34a, 34b, 3
4c is built into the case 21.

Next, the operation of this embodiment will be described.

When the excavating tool is lowered by free hole operation, the operating time relationship of the switches 14a and 14b of the movement direction detector is as shown in FIG.
In order to add
The operation of increasing the value by a (-) value ((-) addition operation) is performed by the pulse from the arithmetic circuit 16.
b converts the integrated value into depth, and the digital value is displayed on the digital display meter 17, and at the same time, the analog quantity obtained by the digital-to-analog converter 18 is displayed on the analog display meter 19. In this case, the value displayed on the digital display meter 17 fluctuates rapidly and is difficult to read, but the depth can be read using the analog display meter 19. Therefore, in the case of an earth drill like this example, the drilling tool is lowered at high speed without applying any brake until it reaches the bottom of the hole, and when the drilling tool approaches the bottom of the hole, the brake is applied to stop it. You can easily land it on the bottom of the hole. This will be explained in detail below. In other words, to determine whether or not the bottom of the hole has been approached, if the previous excavation depth is set in the depth setter 32c, the lamp 35c will flash and the buzzer 36 will sound when the depth is shallower by a preset depth l. You can judge it by looking at it. On the other hand, in the case of a bucket type continuous wall machine, the lamp 35
c flashes and the buzzer 36 starts to sound, apply the brake to temporarily stop the descent of the drilling tool to avoid unnecessary shock to the bottom of the hole, and then drop the drilling tool again using free hole operation. Insert the bucket's claws into the bottom of the hole. In either case, when the bucket is full of earth and sand, it is pulled up to the ground again, but the value of the depth setter 32c is changed to the depth at this time.

In addition, in the case of an earth drill or a Kelly type bucket wall machine, the Kelly bar 4 is usually a multi-stage telescoping type, so as each Kelly bar extends, the protrusions provided on each Kelly bar may catch on each other and sometimes fall out. On the other hand, if it is dropped in a free hole, it may collide violently with the protrusion, causing cracks and damage. For this reason, if the operator does not have a depth gauge, he or she applies the brake by checking the amount of rope unwinding on the winch, and even if the operator has a depth gauge, he or she must memorize the depth that is slightly shallower than the engagement part. There was also a risk of misremembering, leading to operational errors. However, since the positions at which these protrusions engage are fixed, if the engagement position of each stage is set in advance using the depth setters 32a and 32b, the depth will be shallower by l than the engagement position, as explained above. At depth, the lamp 35a flashes and the buzzer 36 starts to sound, so it is possible to descend slowly while applying the brakes, thereby alleviating the impact at the time of engagement. After engagement, the switch is again made to the free hole mode, but at this time the lamp 35a turns on to indicate that the cutest set depth has been passed, and the buzzer 36 stops sounding. Depth setting device 3
The lamp 35b and buzzer 36 operate similarly at the depth set in 2b.

When the excavating tool is pulled up to the ground, the operating time relationship of the switches 14a and 14b of the moving direction detector is as shown in FIG. Therefore, the integration circuit 16a performs an operation of subtracting the value by a (-) value ((-) subtraction operation) using the pulse from the movement amount detector 13.

Normally, the zero reference point for depth is placed on G and L, but when the drilling tool passes through the zero reference point when being pulled up from the bottom of the hole, the internal calculation is a (-) subtraction operation. However, both the digital display meter 17 and the analog display meter 19 apparently perform a (+) addition operation.
For example, if the voltage value when a pulse corresponding to 100 m in absolute value is generated is 10V, if the generated voltage is not returned to 0V when the reset button 20 is pressed, but the base voltage value is set to 2V. A voltage of 0 V is generated at a depth of (+) 20 m, and a voltage of 10 V is generated at a depth of (-) 80 m, making the above display possible.

Also, if the zero reference point of depth is placed on G and L,
For example, with wire rope 2 stretched, bucket 3
When the machine is lowered to the ground, check whether the value displayed on the digital display meter 17 is out of order due to slippage between the wire rope 2 and the sheave 9. If an error has occurred, press the reset button 20 and reset the arithmetic unit. 16
Reset.

Furthermore, if the value of φD, which is the PCD of the sheave 9 shown in FIG.

Note that the present invention is not limited to the above embodiments, and various changes and additions can be made without departing from the gist of the present invention. For example, as the movement amount detector 13 and the movement direction detector 14, other non-contact type switches such as a proximity switch or an ultrasonic switch can be used in addition to the one in this embodiment. Additionally, a movement direction detector 1 provided to instruct the arithmetic unit 16 to perform addition and subtraction.
4 and the discrimination circuit 15 may be replaced by a switch operated by an operator, and addition or subtraction may be performed by switching the switch.

As described above, according to the present invention, since the bracket to which the switch is fixed is attached to the rotating shaft of the sheave, it is easy to position the switch relative to each permanent magnet attached to the sheave. Even if the bolts fixed to the non-rotating parts to suppress the swinging of the bracket loosen, the relative position between the switch and the permanent magnet will not change, so measurement errors can be prevented. Furthermore, even if the bolt falls off and the bracket becomes unfixed, it will only swing around the same rotation axis as the sheave, so there is an effect that the switch will not be damaged.

[Brief explanation of the drawing]

Fig. 1 is an overall side view of an earth drill to which the present invention is applied, Fig. 2 is a block diagram showing an embodiment of the present invention, and Fig. 3 is an example of a movement amount detector and a movement direction detector of the embodiment. Layout diagram showing , Figure 4 is the 3rd
5 is a pulse waveform diagram illustrating the operation of the movement amount detector of this embodiment, and FIG. 6 is a pulse waveform diagram illustrating the operation of the movement direction detector of this embodiment. , FIG. 7 is a block diagram showing an example of the configuration of the arithmetic unit and discrimination circuit in this embodiment, and FIG.
The figure is an external view of the display section of this embodiment. 2...Wire rope, 3...Drilling tool, 9...Sheave,
13a, 13b, 14a, 14b...Switch, 3
7... Rotating shaft, 39... Bolt, 40... Bracket.

Claims (1)

[Claims] 1. In a depth detection device for a pit excavator in which a drilling tool is supported by a wire rope, a depth detection device is used in which a plurality of proximal objects or permanent magnets provided near the outer periphery of a sheave that rotates due to the movement of the wire rope approach. The vertical sheave is characterized in that a bracket to which a switch is fixed is mounted so that the swinging fulcrum is at the center of the rotating shaft of the sheave, and a fixing means for suppressing the swinging of the bracket is provided. Depth detection device for hole drilling machines.