JPH0467559B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a safety device for an earth drill configured to be usable as a crane.

(Prior Art) FIGS. 12 and 13 show an example of an earth drill configured to be usable as a crane and equipped with an overload prevention device for the crane. An upper rotating body 3 is installed via the device 2, a telescopic boom 5 is attached to the upper rotating body 3 so as to be able to rise and fall freely, and a hoisting winch 6 is installed on the upper rotating body 3.
(The hoisting winch 6 consists of a main hoisting winch 6a and an auxiliary hoisting winch 6b installed in parallel with the main hoisting winch 6a.)
Kelly rope 7 wound around the main winding winch 6a of
is hung on sheaves 8 and 9 at the top of the boom 5, a kelly bar 11 is connected to the lower end of the kelly rope 7 via a swivel joint 10, and an earth drill bucket 12 is attached to the lower end of the kelly bar 11. The Kelly bar 11 has a rectangular cross section and is inserted into a square hole of a rotating body of the Kelly bar drive device 14 at the end of the front frame 13.
is attached to a bracket 17 provided at the front part of the upper revolving body 3 by a pin 16 so that it can be raised and lowered freely by a hoisting device 15 consisting of a winch, and can be attached and detached together with the Kelly bar drive device 14 and the hoisting device 15. The Kerry bar drive device 14 is connected to the boom 5
It is supported via a hanging rope 29.

In addition, as shown in FIG. 13, when using the auxiliary hoisting winch 6b installed in parallel to the main hoisting winch 6a as a crane during earth drilling work, the winch of the hoisting device 15 can be used as a crane. Then, the front frame 13 is held in place, and the hook 21 is attached to the tip of the auxiliary winding rope 20 that is hung around the sheaves 8 and 9, and crane work is performed. To make this possible, a sheave 8 is mounted on the top of the boom 5.
Two or more sheaves 9 are provided coaxially, and two or more sheaves 9 are provided coaxially, for example, the Kelly rope 7 is provided on the right sheave 8 and sheave 9, and the auxiliary winding rope 20 is provided on the left sheave 8 and sheave 9. Can be hung.

Additionally, if necessary, a bracket (none of which is shown) having a sheave is attached to the top of the boom 5, and the auxiliary hoisting rope 20 wound around the auxiliary hoisting winch 6b is hung on the sheave to perform crane work. Sometimes I do it.

Furthermore, this ground drill connects the front frame 13 to the Kerry bar drive device 14 and the luffing device 15.
Remove the hoisting rope from the sheave 9 and hook block (not shown) in place of the Kelly rope 7.
It can be used as a crane by hanging between the crane and the crane.

Further, Fig. 6 shows the work mode selection switch 22 in the conventional overload prevention device, where A is the work mode selected when working with a bracket attached to the top of the boom 5, and B is when used as an earth drill. , or when used as a crane using the main hoisting winch 6a (in this case, it is also possible to perform crane work using the auxiliary hoisting winch 6a if necessary), the work mode C is selected. This is the work mode that is selected when working with the auxiliary winding rope 20 when used as an earth drill.Since each type has a different rated load, etc., it is selected according to each work mode. It is.

FIG. 2 shows a part of the electric circuit of a conventional overload prevention device, which automatically stops hoisting due to overload. 24 is a solenoid valve inserted in one of the pressure receiving parts of the control valves of the hydraulic motors of the hoisting winches 6a and 6b, that is, connected to the hoisting operation pressure receiving part.The solenoid 23a is connected to the overload prevention device. It is connected to the power source 26 via a relay contact 25 that closes in response to an automatic stop signal from the controller, and in the event of an overload, the relay contact 25 closes and the solenoid valve 23 is switched from the right position to the left position as shown in the figure. The operating pressure of the winding operation pressure receiving part of the valve becomes the tank pressure, and the winding automatically stops.

In such an earth drill, as shown in FIG. 6, the B position of the work mode selection switch 22 of the overload prevention device is set when used as an earth drill and when used as a crane using the main winding winch 6a. Since it is also used as a work mode for ground drills, the following malfunctions occur when used as a ground drill.

(1) After the excavation work is completed, as shown in Figure 12, when pulling up the bucket 12, the bucket 12 and hole 2
7 The space a with the bottom becomes a vacuum state, the load temporarily increases, and the overload prevention device is activated.
The relay contact 25 in FIG. 2 closes, the solenoid valve 23 switches to the left position, and the hoisting winch hydraulic motor stops.

(2) Also, when pulling up the bucket 12, the upper end of the Kelly bar 11 is connected to the rope 30 from the top of the boom 5.
When the auxiliary hoisting rope 20 supported by the auxiliary hoisting rope 20 contacts the weight 28 for the overwinding prevention switch, the overwinding prevention device stops, and the hydraulic pressure installed commonly on the auxiliary hoisting winch 6a and the main hoisting winch 6b increases. Since the motor stops, winding stops.

Such malfunctions frequently occur when the bucket 12 is pulled up, and even when the bucket 12 is rotated to excavate, the overload prevention device is activated due to the vibrations and shocks caused by the excavation, resulting in unnecessary unnecessary operation. Sometimes it may stop automatically.

Since the earth drill will not fall when the bucket 12 is inside the hole 27, the hoisting stop due to this overload prevention operation does not contribute to improving safety, but only causes a decrease in efficiency.
Therefore, it is conceivable to provide a release mechanism that stops the operation of the overload prevention device during earth drilling work, but when switching to crane work using the auxiliary winding winch 6b, the operator may continue crane work with the overload prevention device released. There is a danger of doing so.

(Problems to be Solved by the Invention) In view of the above problems, the present invention provides a grounding system that can improve work efficiency during excavation work and that does not reduce work safety during crane work. The purpose is to provide safety equipment for drills.

(Means for Solving the Problems) In order to achieve this object, the present invention provides an earth drill equipped with an overload prevention device for a crane, which uses a boom hoisting lever or a boom and a boom lever when used as an earth drill. a device for locking the telescoping lever and a locking position of the locking device;
and an automatic stop release switch that switches in the unlocked position, and the automatic stop release switch is connected to at least the operating circuit of the overload prevention solenoid valve inserted into the hoisting side operating conduit of the control valve of the hydraulic motor for the hoisting winch. When the locking device is inserted and the locking device is in the locked position, the automatic stop release switch is turned off, thereby preventing the overload prevention solenoid valve from switching to the hoisting inhibiting side in the event of an overload. Features.

Further, the present invention provides that the earth drill has a work mode selection switch, and operates depending on whether or not the crane work mode is one of the work modes selected by the work mode selection switch. An automatic stop release relay that becomes inactive is provided, and the contact of the automatic stop release relay is connected to at least the operating circuit of an overload prevention solenoid valve inserted into the hoisting side operating conduit of the control valve of the hydraulic motor of the hoisting winch. By inserting the solenoid valve, when used as an earth drill, the circuit structure is such that the solenoid valve is prevented from switching to the hoisting inhibiting side in the event of an overload.

The present invention also provides at least an overload activation switching element and an overload activation switching element inserted in series with the operation circuit of an overload prevention solenoid valve inserted into the hoisting side operation conduit of the control valve of the hydraulic motor of the hoisting winch. an automatic stop release switching element that is turned on by the operation of a manually operated automatic stop release switch and prohibits the operation of the overload activation switching element; and the automatic stop release switching element The present invention is characterized by comprising a circuit for resetting the operating state of the device using a reset switch.

In addition, by providing the automatic stop release switch with a function that not only releases the automatic stop caused by the overload prevention device but also the automatic stop caused by the overwinding of the auxiliary winding rope, it is possible to prevent the overloading of the auxiliary winding rope during earth drilling work. This prevents the winding from stopping due to winding switch activation.

(Example) An example of the present invention will be described below with reference to the drawings.
FIG. 1 is an electric circuit diagram showing an example of an overload prevention circuit in a hoisting circuit of the present invention. In this embodiment, a relay contact 25 activated by a signal emitted at the time of overload in an overload prevention device and an automatic hoisting circuit are shown. Solenoid 23 of stop solenoid valve 23
An automatic stop release switch 30 and a switch 3 that closes in conjunction with the engagement of the auxiliary winding clutch lever are connected between the
1 are connected and inserted in parallel.

The automatic stop release switch 30, as shown in FIG. 3 and FIG.
and whether the locking tool 34 that locks the telescopic lever 33 of the boom 5 is in the locked-on state.
Alternatively, it is installed so that it can be opened or closed depending on whether the lock is in the lock-off state. That is,
A stand 35 is installed near the levers 32 and 33, a shaft 36 is attached to the stand 35, and the shaft 3
A cylindrical body 37 is rotatably fitted into the cylindrical body 3.
A U-shaped locking tool 34 is attached to the lever 7, and when the locking tool 34 is in the position retracted from the levers 32 and 33 as shown by the two-dot chain line a in FIG. The levers 32, 33 can be moved freely by operating them, and the contacts of the switch 30 are closed, but the levers 32, 33 can be moved by turning the locking tool 34, as shown by the solid line in FIGS. 3 and 4.
If it is pinched, the movement of the levers 32 and 33 in the direction of arrow b is blocked, and the striker 38 attached to the cylindrical body 37 presses the operating rod 30a of the switch 30, changing the switch 30 from the closed state to the open state. It is something that changes.

According to this embodiment, during the earth drilling operation,
Boom hoisting lever 32 and boom telescoping lever 3
3 is not operated, these levers 32 and 33 are in a locked state to prevent erroneous operation as shown in FIGS. Therefore, even if the overload prevention device is activated and the relay contact 25 is closed, the automatic stop solenoid valve 23 will not be switched and will not automatically stop.

On the other hand, when removing the front frame 13, Kelly bar 11, etc. and performing crane work using the main winding winch 6a, it is necessary to operate the boom hoisting lever 32 and the boom telescoping lever 33, so the locking tool 34 is Since the lock is always released in the retracted position shown in a in the figure, the automatic stop release switch 30 is closed, and when the overload prevention device is activated and the relay contact 25 is closed, the automatic stop solenoid valve 23 is closed. The winding will be automatically stopped.

Therefore, when the lever is locked and unlocked at the same time as the earth drilling work and the crane work are recombined, the overload prevention device is automatically and reliably turned on and released, and the overload prevention device is not turned on by the operator. , no release operation is required.

Additionally, an auxiliary clutch lever interlocking switch 31 connected in parallel to the automatic stop release switch 30
is closed when switching from earth drilling work to crane work using the auxiliary winding winch 6b.
When using the auxiliary winding winch 6b, consideration is given to the fact that crane work is performed without necessarily extending/contracting or raising/lowering the boom 5.
The auxiliary winding clutch lever transmits or releases the rotation of a drum driven by a hydraulic motor shared with the main winding winch 6a to the drum of the auxiliary winding winch 6b. As shown in FIG. 5, the auxiliary clutch lever 40 is rotatably mounted around a shaft 41, and has a rod 42 connected to a clutch (not shown) at the tail end of the lever 40. The auxiliary winding clutch lever interlocking switch 31 is provided near the rod 42, and the switch 31 is open when the auxiliary winding clutch lever 40 is in the non-operating position, as shown in FIG. When performing crane work using the auxiliary winch 6b, the lever 40 is operated as shown by arrow C in FIG.
The striker 43 attached to the switch 2 moves as shown by arrow d and pushes the operating rod 31a of the switch 31, and the contact point of the switch 31 closes.

Therefore, if the overload prevention device is activated and the relay contact 25 is closed during hoisting by the auxiliary winch 6b, the automatic stop solenoid valve 23 is switched and the hoist is automatically stopped.

In addition, earth drill work and auxiliary winding winch 6b
When switching between crane work and
The overload prevention device is automatically and reliably engaged and released in conjunction with the operation of the auxiliary winding clutch lever 40, and there is no need for an operator to engage and release the overload prevention device.

In addition, as shown by the dotted line in FIG. 1, an overwinding switch 2 for detecting overwinding of the auxiliary winding rope is connected in parallel to the contact 25 activated by the overload prevention device.
If a relay contact 90 operated by 8 is provided,
It is possible to prevent winding from stopping due to malfunction of the overwinding switch during earth drilling work.

FIGS. 7 and 8 show other embodiments of the present invention. Conventionally, there were three positions A, B, and C that could be selected by the work mode selection switch 22 as shown in FIG. The positions are designed to be used both when used as an earth drill and when used as a crane using the main winding winch 6a, but in this embodiment, the four positions A, B, D, and C are used.
B is set for exclusive use of the earth drill, and D is set for the crane work mode using the main winding winch 6a. In addition, when the work mode selection switch 22 is set to position D and crane work is performed, the automatic stop release relay 4 is set as shown in FIG.
4 is energized and its contact 44a is closed.

Therefore, in this embodiment as well, when the operator operates the work mode selection switch 22 at the start of work, the overload prevention device is automatically turned on and off. Furthermore, when performing crane work using the auxiliary winding winch 6b during earth drilling work, the auxiliary winding clutch lever interlocking switch 31 is closed, as explained in the previous embodiment, so that the hoisting operation in the event of overload is prevented. Automatic stop occurs.

9 to 11 show other embodiments of the present invention. In FIG. 9, 61 is an overload prevention device main body, and a hydraulic cylinder 4 for raising and lowering the boom 5.
A load detection section 6 provided at the connection section with the boom 5 of
2, boom length detector 63, and boom angle detector 64 as input, perform necessary calculations, compare the results with internally stored values, and if there is an overload, A solenoid valve 66 (actually, a plurality of solenoid valves) is inserted into the pilot circuit of each control valve to drive the relay unit 58 to sound the buzzer 65 and to stop the hoisting, boom extension, and boom lowering depending on the situation. (However, only one is shown.)
It operates. Reference numeral 51 denotes a control device provided in accordance with the present invention, which includes an automatic stop release switch 55 that cancels automatic stop and alarm generation by the overload prevention device, and a reset switch 56 that restores the canceled automatic stop and alarm generation functions.
A lamp 57 is provided that lights up when the automatic stop or alarm generation function is canceled. A sensor 53 is inserted into the operating circuit of the boom hoisting lever 32 and operates by detecting the operating pressure, and a sensor 54 operates by detecting the operating pressure of the front frame hoisting device 15. These sensors 53 and 54 may be provided in the drive circuit instead of the operation circuit.

FIG. 10 is a circuit diagram showing the control device 51 and relay unit 58 shown in FIG. 9. Reference numeral 25 indicates a contact point of a sensor that closes in response to a signal from the overload prevention device main body 61 at the time of overload, and 70 to 76 indicate switching transistors. Now, when the sensor contact 25 closes during an overload, the transistor 70, which is a switching element for overload operation, turns on.
When the buzzer 65 sounds, the solenoid valve 66 is activated to stop hoisting, boom lowering, or boom extension. Furthermore, when the contact 25 closes, a current flows through the circuit 78 having the capacitor 77, so that a base current flows through the transistor 71, turning on the transistor 71, and as a result, current flows through the circuit 79, causing the transistor 7
The base potential of transistor 2 rises to turn on transistor 72, and the base current of transistor 71 flows through transistor 72, so that even if contact 25 is opened, these transistors 71 and 72 remain on. do. While these transistors 71 and 72 are in the on state,
The collector of transistor 71 is connected to the bases of transistor 73, which is a switching element for automatic stop cancellation, and transistor 75, which is a switching element for reset, through diodes 80, 81, resistors 82, 83, and resistor 84, respectively. These transistors 7
3,75 from turning on.

When performing earth drilling work, when the automatic stop release switch 55 is operated and closed, the resistance 8
2. A base current flows to the transistor 73 via the capacitor 85, and the transistor 74 is turned on according to the same principle as described above and maintained in the on state. In this case, since the collector of the transistor 73 is connected to the base of the transistor 70 via the transistor 86, the base potential of the transistor 70 is pushed up, and the transistor 70 is turned off. Therefore, the solenoid valve 66 does not operate.
Buzzer 65 also does not sound.

On the other hand, when the reset switch 56 is operated and closed, the transistor 75 is turned on via the capacitor 87 and the limit switch 56, and the transistor 76 is also turned on and maintained in the on state based on the same principle as the circuit described above. Further, the collector of the transistor 75 is connected to a diode 8, respectively.
The transistor 75 is connected to the bases of the transistors 71 and 73 via the transistors 8 and 89.
By turning on, the transistors 71 to 7
4 is off. Thereby, when the contact 25 is closed, the transistor 70 is turned on, and an operation for overload prevention is performed.

In addition, for the reset switch 56, a contact 53a of a sensor 53 that operates by detecting the operating pressure of the boom hoisting lever 32 and a contact 54a of a sensor 54 that operates by detecting the operating pressure of the front frame hoisting device 60 are connected. are connected in parallel, so when transitioning from earth drilling work to crane work using the auxiliary winding winch 6b, the front frame 13 must be raised, so the sensor contact 53a closes, which is the same as when the limit switch 56 is operated. The overload prevention device becomes operational. In addition, the front frame 13
Even when performing crane work without causing
Since crane work cannot be carried out due to the Kerry bar 11 being a hindrance in the working radius in the excavation position, the angle of the boom 5 must be changed, so the sensor contact 54a closes, so the overload prevention device can still be activated. . The above operation is performed in the first
This is shown in the time chart in Figure 1.

In the above embodiment, the case where the boom 5 is a telescoping boom has been described, but the present invention can also be applied to a case where the boom 5 is a non-retractable boom. The present invention can also be applied to the configuration.

(Effects of the Invention) As described above, in the present invention, since a switch is provided to cancel the automatic stop caused by the overload prevention device, during earth drilling work, the overload prevention device Even if a malfunction occurs, it will not automatically stop, improving work efficiency.

In addition, crane work using a main winding winch,
Alternatively, if a crane is working with an auxiliary winding winch during an earth drill, we have installed a device that automatically returns the automatic stop release switch.
It is safe because it prevents erroneous operation due to incorrect switching of the automatic stop release switch.

In addition, by providing the automatic stop release switch with a function that not only releases the automatic stop caused by the overload prevention device but also the automatic stop caused by the overwinding of the auxiliary winding rope, it is possible to prevent the overloading of the auxiliary winding rope during earth drilling work. It is possible to prevent the winding from stopping due to the operation of the winding switch, and further improve work efficiency in earth drilling work.

[Brief explanation of the drawing]

Fig. 1 is an electric circuit diagram showing an embodiment of the safety device according to the present invention, Fig. 2 is an electric circuit diagram showing a conventional safety device, and Fig. 3 is a lever lock of the automatic stop release switch in the embodiment of Fig. 1. 4 is a side view showing the operating mechanism attached to the device, FIG. 4 is a sectional view taken along line AA in FIG. 3, and FIG. 5 is an operating mechanism attached to the auxiliary wrap clutch lever of the automatic stop release switch in the embodiment of FIG. 1. FIG. 6 is a side view showing a conventional work mode selection switch, FIG. 7 is a view showing a work mode selection switch according to another embodiment of the present invention, and FIG.
The figures are electrical circuit diagrams related to the embodiment shown in Fig. 7;
The figure is a device configuration diagram showing another embodiment of the present invention.
0 is a partial electric circuit diagram of the embodiment, FIG. 11 is a time chart for explaining the operation of FIG. 10, and FIG. 12 is a side view showing an example of a conventional earth drill.
FIG. 3 is a side view showing the crane operating state using the auxiliary winding winch.

Claims (1)

[Scope of Claims] 1. An earth drill equipped with an overload prevention device for a crane, which includes a device that locks a boom hoisting lever when used as an earth drill, and a device that switches between a locking position and a non-locking position of the locking device. an automatic stop release switch, the automatic stop release switch being inserted into an operating circuit of an overload prevention solenoid valve inserted into at least a hoisting side operating conduit of a control valve of a hydraulic motor for a hoisting winch; In the lock position, the automatic stop release switch is turned off, so that
A safety device for an earth drill, characterized in that the overload prevention solenoid valve is configured to prevent switching to a hoisting prohibition side in the event of an overload. 2. A safety device for an earth drill according to claim 1, wherein the earth drill has a telescoping boom, and the locking device is configured to lock a boom hoisting lever and a boom telescoping lever. . 3. According to claim 1 or 2, the earth drill has an auxiliary winding clutch lever that transmits the rotational force of the hoisting hydraulic motor to the auxiliary winding winch drum, and the automatic stop release switch comprises: An interlocking switch is connected in series to a relay contact activated in the event of an overload and connected to a solenoid of the solenoid valve, and is switched in conjunction with engagement and release of the auxiliary winding clutch lever, and is connected in parallel to the automatic stop release switch. A safety device for an earth drill, characterized in that it has a configuration. 4. In the earth drill equipped with an overload prevention device for a crane, the earth drill has a work mode selection switch, and the crane work mode is one of the work modes selected by the work mode selection switch. an automatic stop release relay that is activated or deactivated depending on whether the An earth drill characterized by having a circuit configuration that prevents the solenoid valve from switching to the hoisting inhibiting side in the event of an overload when used as an earth drill by inserting the solenoid valve into the operation circuit of the prevention solenoid valve. Safety device. 5. In claim 4, the earth drill has an auxiliary winding clutch lever that transmits the rotational force of the hoisting hydraulic motor to the auxiliary winding winch drum, and the contact point of the automatic stop release relay is configured to prevent overload. An interlocking switch is connected in series to a relay contact that is activated when the solenoid valve is activated, and is connected to the solenoid of the solenoid valve, and is switched in conjunction with closing and releasing of the auxiliary clutch lever, and is connected in parallel to the contact of the automatic stop release relay. A safety device for an earth drill as described above, characterized in that it has a configuration. 6. In an earth drill equipped with an overload prevention device for a crane, at least A switching element for activation under load, a sensor contact that closes during overload, and a switching element for automatic stop release that is turned on by the operation of a manually operated automatic stop release switch and prohibits the operation of the switching element for activation during overload. and a circuit for resetting the operating state of the automatic stop release switching element using a reset switch. 7 In claim 6, the reset circuit includes a contact point of a pressure sensor provided in the operation circuit or drive circuit of the front frame hoisting device, and a pressure sensor provided in the operation circuit or drive circuit of the boom hoisting lever. A safety device for an earth drill, comprising a contact point.