JPH10296574A - Feeder for core drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage in a core drill by arranging a frictional clutch, which slips when a feed motor is overloaded, in a mechanism transmitting power from the feed motor to a pinion. SOLUTION: When electric current is let flow into a coil so as to excite an electromagnet 35, a friction member 33 and a friction plate 36 are attracted, and power of a feed motor is transmitted to a shaft 37 via a worm gear device 23, a solenoid clutch 24, and a reduction gear 25, so that a pinion is driven rotationally. In this way, the pinion is moved along a rack, and feeding is carried out. During cutting, when an edge point of a core pit collides against a reinforcement or against a stopper arranged in the rack and a feeding load is increased, the friction member 33 and the friction plate 36 slip, and as a result, application of an abnormal load to the feed motor can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core drill feeder used for drilling reinforced concrete.

[0002]

2. Description of the Related Art As shown in FIG. 1, a pillar 2 vertically mounted on a base 1, a core drill body 3 supported up and down on the pillar 2, and a core bit 4 attached to the core drill body 3 are known as core drills. The core drill body 3 includes a feed motor 6 for driving a pinion (not shown) that meshes with a rack 5 attached to the column 2 via a reduction gear, and a cutting for rotating the core bit 4 via a reduction gear. There is a type in which a feed motor 7 is provided and feed is controlled by a control device and is automatically fed.

[0003] In this type of core drill, a cutting target current is generally set in order to perform drilling with a constant load, and feed is controlled so that the current value of the cutting motor becomes the target current. FIG. 2 shows the control device of the core drill, and a sensor 9 for detecting a current value of the cutting motor 7.
, A setter 10 for setting a current value, a comparator 11 for comparing a target current value set in the setter 10 with a current value detected by the sensor 9, and a feed motor controlled by the comparator 11. 6 comprising a current regulating device 12,
When the current value detected by the sensor 9 increases or decreases due to the increase or decrease of the cutting resistance, the current of the feed motor 6 is adjusted by the current adjusting device 12 to change the feed speed.

[0004]

Since a large thrust is required for feeding the core bit, a DC motor is generally used as a feed motor, and the feed is performed by rotating a pinion through a speed reducer having a large reduction ratio. Is performed. Also, when attempting to drill reinforced concrete with a constant load, a large difference occurs in the cutting feed speed of the core bit between the concrete portion and the reinforcing bar portion, the cutting edge of the core bit hits the reinforcing bar, and when the load increases, the feed speed decreases, Even if control responsiveness is increased, the feed speed does not sufficiently decrease due to inertia, and as a result, the feed motor may be temporarily overloaded at the beginning when it hits a reinforcing bar. To further improve the control response speed to prevent this, a hunting phenomenon occurs, and the control device becomes complicated and expensive.

When the feed of the core bit is controlled by the current comparison control for keeping the load at the time of drilling constant as described above, when the cutting edge of the core bit becomes worn and cannot be cut, or when extremely small diameter drilling is performed. At this time, the current value of the cutting motor becomes equal to or less than the target value, so that the feed motor attempts to increase the feed force and the feed speed. as a result,
An excessive force is applied to the core drill to break it, or the anchor 8 for fixing the base of the core drill to reinforced concrete comes off.

In the above-mentioned automatic feed type core drill, when drilling to a predetermined depth and stopping the drill,
The stopper is attached to the rack of the column, and the slide block of the core drill is applied to the stopper and stopped. However, even when the stopper is stopped, the load of the cutting motor is reduced and the feed motor may be overloaded and damaged. An object of the present invention is to provide a core drill capable of solving the above-mentioned problem.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a mechanism for transmitting power from a feed motor to a pinion with a friction clutch that slips when the feed motor is overloaded. That is, the present invention comprises a column vertically provided on a base, a core drill body supported up and down on the column, and a core bit attached to the core drill body, wherein the core drill body has a pinion meshing with a rack attached to the column. In a core drill provided with a feed motor that rotationally drives the motor and a cutting motor that rotationally drives the core bit, the core drill includes a feed motor, a pinion, and a power transmission mechanism that transmits power from the feed motor to the pinion. In
A friction clutch that slips when the feed motor is overloaded is provided.

As the speed reducer used in the power transmission mechanism of the present invention, a worm gear device is desirable. The reason is that it is compact and can have a large reduction ratio, and the worm gear acts as a self-lock to prevent the core drill body attached to the support from falling naturally due to its own weight, set the core bit, and position the core bit This is because it is not necessary to adjust the position of the core drill, or to support the core drill body by hand at the start of drilling, or to fix the core drill body to the support with screws.

As the friction clutch used in the present invention, for example, a plate clutch, a conical clutch, a rim clutch and the like can be used, but an electromagnetic clutch is preferably used. When the current supply to the electromagnetic clutch is cut off,
The core drill body can be smoothly moved up and down along the column, and the core drill body can be smoothly pulled up after the start of drilling or the completion of drilling. In particular, when the worm gear device is used as the speed reducer as described above, it is possible to smoothly move up and down by cutting off the supply of the current to the electromagnetic clutch.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS.
1 shows a gear box 22 containing a power transmission mechanism for transmitting power to a pinion (not shown). The gear box 22 includes a worm gear device 23, an electromagnetic clutch 24, and a reduction gear 25 composed of a planetary gear. Will be described in order.

The worm gear device 22 includes a feed motor 21
Worm 28 fixed to output shaft 27 of gearbox 2 and gearbox 2
The worm wheel 30 is keyed to a clutch shaft 29 which is rotatably supported in the housing 2. The electromagnetic clutch 24 includes a friction member 33 connected to the clutch shaft 29 by a key 32 so as to be slidable in the axial direction, and a coil circling around the clutch shaft 29. An annular electromagnet 35 is fixed to the inside, and a friction plate 36 is slidably supported in the gear box so as to face the friction member 33.

The speed reducer 25 is composed of a set of planetary gears, and a spline shaft 38 protruding from one side is provided with a friction plate 36.
And a shaft 37 projecting from the other side is connected to a pinion shaft (not shown). This device is configured as described above. When the power of the core drill is turned on, the coil is energized to excite the electromagnet 35, the friction member 33 and the friction plate 36 are attracted, and the power of the feed motor 21 is transmitted to the worm gear device 23, Clutch 24
The rotation is transmitted to the shaft 37 via the speed reducer 25 to rotate the pinion, whereby the pinion moves along the rack 5 shown in FIG. 1 and feed is performed. As described above, automatic feed is performed by current comparison control that keeps the load at the time of drilling constant by the control device, but the cutting load of the core bit hits the reinforcing bar during cutting or hits the stopper provided on the rack. If it increases, it is possible to prevent the friction member 33 and the friction plate 36 from slipping and applying an abnormal load to the feed motor 21.

The electromagnet 35 is excited, and the friction member 33
When the feed motor 21 is not driven, the worm gear device 23 performs a self-locking function, the pinion is in a constrained state, and the elevation of the core drill body is stopped, unless the feed motor 21 is driven. When the power of the core drill is turned off and the excitation of the electromagnet 35 is released, the friction plate 36 can freely rotate with respect to the friction member 33, so that the core drill body can be moved up and down smoothly.

[0014]

According to the first aspect of the present invention, when drilling in reinforced concrete, if the cutting edge of the core bit hits the rebar temporarily during cutting and is overloaded temporarily, the feed motor slips by the friction clutch and the feed motor is overloaded. That the control response does not need to be accelerated and that the load on the cutting motor decreases, resulting in an increase in the feed force and feed speed of the feed motor, resulting in an overload of the feed motor. Even if there is, there is no damage to the core drill due to slippage by the electromagnetic clutch.

According to the second aspect of the present invention, since the worm gear device performs a self-locking function, the lifting and lowering of the core drill main body can be stopped. When the core bit is replaced or set, or when positioning or drilling is started. There is no need to support the core drill body by hand or fix it to the support by screws. When the electromagnetic clutch is used as the friction clutch, the excitation of the electromagnetic clutch is released so that the core drill body can be moved up and down smoothly, and the worm gear device is used as the reduction gear. Also, the lifting and lowering of the core drill body can be performed smoothly.

[Brief description of the drawings]

FIG. 1 is a front view of a core drill.

FIG. 2 is a block diagram of a control device.

FIG. 3 is a partial cross-sectional plan view of the power transmission mechanism.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

[Explanation of symbols]

 1. Base 2. Support 3. Core drill body 4. Core bit 5. Rack 6, 21. Feed motor 7. Cutting motor 22. Gear box 23. Worm gear unit 24 .. Electromagnetic clutch 25 Reducer 27 Output shaft 28 Worm 29 Clutch shaft 30 Worm wheel 33 Friction member 35 Electromagnet 36 Friction plate 37 Shaft

Claims (3)

[Claims] A core drill vertically supported on the base, a core drill body supported up and down on the pillar, and a core bit attached to the core drill body;
In a core drill provided with a feed motor that rotationally drives a pinion that meshes with a rack attached to a column and a cutting motor that rotationally drives a core bit, power is transmitted from the feed motor, the pinion, and the feed motor to the pinion. A feed device for a core drill, comprising a power transmission mechanism, wherein a friction clutch that slips when the feed motor is overloaded is provided in the power transmission mechanism. 2. The core drill feeder according to claim 1, wherein a reduction gear comprising a worm gear device is provided in the power transmission mechanism. 3. The core drill feeder according to claim 1, wherein the friction clutch is an electromagnetic clutch.