CN100411784C - Electric drilling device - Google Patents

Abstract

An electric drilling device having a small profile, comprising: a ring cutter, a motor for rotating the ring cutter, a main shaft for rotating the ring cutter mounted on its front end about a rotation axis, disposed between the motor and the main shaft, for A reduction mechanism that transmits the driving force of the motor to the ring cutter through the spindle, a feed mechanism that responds to the operation of the manual handle and is used to move the spindle linearly to advance or retract the ring cutter mounted on the spindle relative to the workpiece, and an attachment base for securing the drill rig to a workpiece. The annular cutter has a plurality of cutting teeth consisting of a carbide tip fixed to its lower end so as to be able to rotate at high speed. The main shaft has a rotation axis that turns in a different direction than the rotation axis of the motor, thereby allowing the electric drilling apparatus to have a smaller profile.

Description

electric drilling equipment

technical field

The present invention relates generally to an electric drill apparatus, and more particularly to an electric drill apparatus having a low profile and for automatically re-driving an electric drill motor when rotation of the electric drill motor ceases in an overload condition.

Background technique

Currently, in new construction, repair, etc. of various buildings and the like, it is necessary to drill workpieces including structural materials such as steel covers to be set at or near a position where the workpiece is installed on the building. Therefore, there is a need to transport such electric drilling equipment to a workpiece assembly location. Additionally, drilling operations often must be performed in relatively confined spaces at or near where structural materials or workpieces are installed. Therefore, such electric drilling equipment needs to be reduced in size and weight in order to be easily transported and handled in a small operating space.

Conventional electric drill equipment usually includes a motor, a spindle for supporting and moving a tool for cutting in a vertical direction through a sliding mechanism, and a transmission mechanism for transmitting the energy of the electric drill motor to the spindle to rotate the tool. Arranged vertically or along the direction of movement of the main shaft. These vertically arranged electric drilling devices are generally large in size and thus can only be used in a limited operating area and limit portability.

In contrast, WO 00/54915 discloses a relatively low profile electric drill in which the spindle has an axis of rotation substantially perpendicular to the axis of rotation of the electric drill motor. This small electric drilling apparatus has a reduced overall length compared to a vertical arrangement type, and its compact size improves its portability.

In addition, Japanese Patent Document (Kokoku) No. 3-78205 and Japanese Patent Document (Kokai) No. 2003-25122 disclose vertical arrangement type electric drill apparatuses, each of which includes a function of automatically stopping driving of a motor in case of overload.

The above small-sized electric drills have an electromagnetic base for fixing the electric drill to a workpiece so that a stable drilling operation can be performed. However, in order to keep the size of the drilling device small, the electromagnetic base of the device is made small, along with other parts of the device. Due to its small size, the electromagnetic base can only exert a small attractive force. Therefore, this drilling apparatus suffers from the disadvantage that its drilling capacity is limited.

Also, although the automatic electric drill device described in the above Japanese Official Gazette has an automatic stop function in the event of motor overload, this function is only in the electric drill device including an automatic shift mechanism that moves the main shaft in the vertical direction supply. Therefore, there is not yet any electric drilling device which has a manual displacement mechanism for the annular cutter, provided with control means for automatically stopping the drive of the motor in the event of motor overload. Furthermore, there has not been any electric drilling apparatus that has a function of re-driving the motor after the motor is automatically stopped due to motor overload.

Contents of the invention

The present invention has been made in view of the above problems occurring in the prior art electric drill apparatuses exemplified above.

It is an object of the present invention to provide a small electric drilling apparatus with reduced size and weight.

Another object of the present invention is to provide a small electric drill that can be reliably fixed on a workpiece.

Still another object of the present invention is to provide an electric drill apparatus capable of automatically re-driving a motor after the motor is automatically stopped due to overload and having a simple structure to improve operability.

Another object of the present invention is to provide an electric drill capable of identifying the normal and overloaded working conditions of the motor.

In order to achieve the above object, the present invention provides in a first aspect an electric drill device with a smaller profile, the device comprising:

main body;

a motor mounted on the main body;

a main shaft having an axis and for holding an annular cutter coaxial with said axis, the annular cutter having a plurality of teeth made of carbide tips fixed at its lower end, so that the annular cutter can be rotated at a high speed for cutting;

A reduction mechanism, the reduction mechanism is arranged between the motor and the main shaft, and is used to transmit the driving force of the motor to the ring cutter through the main shaft;

a feed mechanism for moving the spindle along its axis in response to operation of the manual lever to advance or retract the annular tool mounted on the spindle relative to the workpiece; and

Attachment base for fixing the electric drilling equipment on the workpiece;

The motor is capable of rotating the ring tool at a suitable high speed for high speed cutting operations by the ring tool having a carbide tip; The directions of the axes extend in different directions.

In an embodiment of the electric drill apparatus, the apparatus further comprises an automatic motor stop/re-drive mechanism comprising: a main switching element connected in series between the motor and the power supply; a current detector for detecting the current flowing through the motor a load current; a determination unit for determining whether the load current detected by the current detector exceeds a first predetermined reference value; and a control unit for controlling the main switching element to turn on/off, wherein the load current is determined at the determination unit When the first reference value is exceeded, the control unit turns off the main switching element to cut off the current flowing through the motor, and then when the determination unit determines that the load current falls below the first reference value, the control unit turns on at a predetermined time after the determination. The main switching element to supply current to the motor from the power supply. Preferably, the attachment mount comprises a magnetic mount with magnets, and/or the axis of the main shaft is substantially perpendicular to the axis of the rotational shaft of the motor.

In a second aspect, the present invention also provides an electric drill device, the device comprising:

a motor for rotating the ring cutter;

a main switching element connected in series between the motor and the power supply;

A current detector for detecting the load current flowing through the motor;

a determining unit for determining whether the load current detected by the current detector exceeds a first predetermined reference value; and

a control unit for controlling ON/OFF of the main switching element, wherein when the determination unit determines that the load current exceeds a first reference value, the control unit turns off the main switching element to cut off the current flowing through the motor, and then determines at the determination unit When the load current decreases to less than the first reference value, the control unit turns on the main switching element at a predetermined time after the determination to supply current from the power source to the motor.

In an embodiment of the electric drilling apparatus of the second aspect, the apparatus further comprises a main shaft having an axis and orbiting the annular cutter mounted on the front end thereof along the axis of rotation of the motor for transmitting the driving force of the motor to the main shaft. The axis of rotation extends in different directions. In this embodiment, it is preferred that the axis of the main shaft is substantially perpendicular to the axis of the rotation shaft of the motor.

In an embodiment of the electric drilling apparatus of the second aspect, the annular cutter includes cutting teeth made of carbide inserts fixed at a lower end thereof at positions respectively facing the plurality of chip flutes.

In an embodiment of the electric drilling apparatus of the second aspect, the apparatus further includes: a second determination unit for determining whether the load current detected by the current detector exceeds a second reference value smaller than the first reference value; and the load A condition indication unit for indicating a normal load condition when the second determining unit determines that the load current does not exceed the second reference value, and indicating an overload condition when the second determining unit determines that the load current exceeds the second reference value. In this embodiment, it is preferred that the current detector is a fixed resistor connected in series with the motor and the main switching element for outputting a correspondingly obtained voltage across the resistor corresponding to the load current, and the second determination unit uses to receive a voltage corresponding to the load current, and compare the voltage with a second reference voltage corresponding to a second reference value to determine whether the load current exceeds the second reference value.

In an embodiment of the electric drilling apparatus of the second aspect, the current detector is a fixed resistor connected in series with the motor and the main switching element for outputting a voltage obtained across the resistor corresponding to the load current, and the first determination Means for receiving a voltage corresponding to a load current and comparing the voltage with a first reference voltage corresponding to a first reference value to determine whether the load current exceeds the first reference value.

In an embodiment of the electric drilling device of the second aspect, the control unit includes: an "on" state self-maintaining unit, which includes a first switching element for maintaining the first switching element at "on" when the starting switch is turned on. "on" state; the control signal providing unit is used to provide the "on" control signal, so that the main switching element is turned on when the first switching element is in the "on" state; the second switching element, which is in the first determination unit When it is determined that the load current exceeds the first reference value, it is turned on, so as to prevent the control signal providing device from generating the "on" control signal regardless of the first switching element being in the "on" state; A unit responsive to determining that the load current has dropped below the first reference value after the first reference value is configured to turn off the second switching element at a predetermined time after the determination.

In an embodiment of the electric drilling apparatus of the second aspect, the main switching element is a triac, and the control unit comprises: an "on" state self-holding unit comprising a first switching transistor for holding the first switching transistor in an "on" state when the switch is turned on; a photodiode for emitting light by being supplied with current when the first switching transistor is in the "on" state; a phototriac element, which is connected between the gate and the anode or cathode of the triac and is optically coupled to the photodiode so that the phototriac is turned on by the light emitted by the photodiode to providing a gate current to the triac; a second switching transistor, responsive to the determination by the first determination unit that the load current exceeds a first reference value, for bypassing the current of the photodiode to communicate with the first switching transistor The photodiode is turned off irrespective of whether the transistor is in the "on" state; the unit responding to the determination by the first determination unit that the load current has fallen below the first reference value after the load current exceeds the first reference value is used for subsequent determination. The second switching transistor is turned off at a predetermined moment.

Description of drawings

Fig. 1 is a side view showing the appearance of an electric drilling apparatus having a smaller profile according to one embodiment of the present invention;

FIG. 2 is a plan view of the electric drilling apparatus shown in FIG. 1;

Figure 3 is a cutaway side view of the electric drilling apparatus; and

Fig. 4 shows a circuit diagram of the electric drill motor controller in the electric drill apparatus according to the present invention.

Detailed ways

An electric drill apparatus according to an embodiment of the present invention will now be described with reference to FIGS. 1-3.

As shown in Figure 1, this electric drill equipment comprises: main body 14, and it is provided with electric drill motor 12; Main shaft 18, is used for rotating the annular cutter t that is installed in the lower end of main shaft 18; Feed mechanism 20, is used for making annular cutter t advance and retraction; and an electromagnetic base lead, which remains on the bottom of the main body 14 and contains an electromagnet for fixing the main body 14 to the steel or the like to be drilled. The electric drilling device also includes a manual operating lever 39 for driving the feed mechanism 20 and a handle 42 located at an upper position of the main body 14 above the motor 12 . Motor 12 is fixed in body 14 with its output shaft oriented horizontally.

As shown in FIG. 2 , the power switch SWPW is provided on the top surface of the handle 42 . A momentary return start switch SWon and a stop switch SWoff are also provided on the top surface of the handle 42 for starting and stopping the motor 12 respectively. In addition, indicator lights LED1 and LED2 are arranged on the top surface of the handle 42 to indicate the load current of the motor 12 . As will be described in more detail later, LED1, when on, indicates normal load current, while LED2, when on, indicates an overload (mild or severe) condition.

When the operator turns on the power switch SWPW, electric power is transmitted to the electromagnet 53 (FIG. 4) in the electromagnetic base 41, thereby fixing the electric drilling device on the workpiece. The magnetic base 41 is preferably configured such that its position relative to the main body 14 is adjustable. By making the relative position adjustable, the main body 14 can be moved to center the annular tool t relative to the workpiece after the magnetic base 41 is fixed on the workpiece.

3, the reduction mechanism 17 connected between the output shaft 12a of the motor 12 and the main shaft 18 includes: a helical gear 17a, a planetary gear reducer 17b and spur gears 17c, 17d, 17e. The reduction mechanism 17 decelerates the rotation of the electric drill motor 12 and changes the direction of the axis of rotation by 90° so that the main shaft 18 has a rotation axis extending in the vertical direction rotated by 90° from the direction of the axis of rotation of the motor 12 .

Main shaft 18 includes a proximal rotational shaft 22 , an intermediate rotational shaft 24 , a distal rotational shaft 26 and a retaining cylinder 28 . The proximal rotation shaft 22 is installed on the main body 14 so as to rotate about a vertical central axis and is connected with the spur gear 17 e of the reduction mechanism 17 . The intermediate rotational shaft 24 is telescopically mounted on the proximal rotational shaft 22 by a splined connection and is movable between an extended position (not shown) and a retracted position (shown in FIG. 3 ). The intermediate shaft 24 slightly overlaps the proximal rotational axis 22 in the axial direction in the extended position, and largely overlaps the proximal rotational axis 22 in the axial direction in the retracted position, and they overlap the proximal rotational axis 22 in the axial direction. The rotating shaft 22 rotates together. The distal rotating shaft 26 is telescopically mounted on the intermediate rotating shaft 24 by a splined connection, and is movable between an extended position (not shown) and a retracted position (as shown in FIG. 3 ), in which, The distal axis of rotation 26 slightly overlaps the intermediate axis of rotation 24 in the axial direction, and in the retracted position the distal axis of rotation 26 largely overlaps the intermediate axis of rotation 24 in the axial direction. The distal rotation shaft 26 rotates together with the intermediate rotation shaft 24 . The holding cylinder 28 rotatably holds the distal rotating shaft 26 and is mounted on the main body 14 so as to move together with the distal rotating shaft 26 in the axial direction. The holding cylinder 28 is supported axially movable while being prevented from rotating by means of a guide cylinder 29 fixed in the main body 14 .

A needle bearing 30 is interposed between the distal rotating shaft 26 and the holding cylinder 28 . A locking ball (locking member) 26 a is installed at the front end of the distal rotating shaft 26 for holding the annular cutter t inserted into the leading end of the distal rotating shaft 26 . A rotary operation sleeve 26b for operating the locking ball 26a is also provided.

As shown in Figure 3, the feed mechanism 20 includes: a movable rack 31, which is installed on the outer surface of the holding cylinder 28 and extends parallel to the axis of the main shaft 18; a fixed rack 32, which is connected to the movable rack 31 are fixed on the main body 14 in parallel and spaced apart; and a pinion 34 which is arranged between the two racks 31, 32 and meshes with them.

When no drilling operation is in progress, the elements of the spindle 18 remain in the retracted position, as shown in FIG. 3 . Then, in performing the drilling operation, when the electric drill motor 12 rotates the annular cutter t through the reduction mechanism 17 and the proximal rotation shaft 22, the intermediate rotation shaft 24, and the distal rotation shaft 26, the operation lever 39 is manipulated, thereby making the small The gear 34 rotates and advances downward on the fixed rack 32 to move the movable rack 31 downward relative to the pinion 34 . Thus, the intermediate rotation shaft 24 and the distal rotation shaft 26 are set in an extended state, so that the main shaft 18 is brought into the extended state, so that the annular tool t mounted on the front end of the distal rotation shaft 26 advances toward the workpiece.

The feed motor of the electric drill can be arranged such that the motor is drivingly connected to the feed mechanism 20 through a clutch so as to extend or retract the main shaft 18 . In this way, it is possible to choose whether to disengage the clutch to move the annular cutter t manually or automatically.

As shown in FIG. 1, a plurality of cutting teeth t2, each formed of a carbide tip, are fixed at positions respectively facing chip flutes t1. By fastening the cutting tooth t2, which consists of a carbide tip, to the cutting edge of the ring tool t, it is possible to increase the rotational speed without causing chipping of the cutting edge. This is in contrast to ring knives made of high speed steel. Therefore, cutting resistance can be reduced, and cutting speed can be increased.

Therefore, the electric drilling apparatus employing the annular cutter having the carbide tip as in the present invention can increase the drilling feed rate; and thus obtain improved productivity of the drilling operation.

In "How to Select and Use Tools" page 16 (First Edition, published by Kabushiki Kaisha Taiga Shuppan) the cutting speeds for ring tools with carbide tips and for ring tools made of high speed steel are described cutting speed.

The motor 12 is selected to rotate at high speeds (eg, four times higher than prior art examples) and is suitable for cutting operations with annular cutters having carbide inserts.

Next, the structure and operation of the electric drill motor controller for driving/stopping the motor 12 of the electric drill apparatus shown in FIGS. 1-3 will be described with reference to FIG. 4 .

In FIG. 4 , reference numeral 50 denotes an external AC power supply, 51 is a full-wave rectification circuit, and 52 is an AC/DC converter. The full-wave rectification circuit 51 applies electric power to the electromagnet 53 contained in the electromagnetic base 51 . When the power switch SWPW connected between the external AC power source 50 and the AC/DC converter 52 is turned on, the full-wave rectification circuit 51 rectifies the voltage from the external AC power source 50 and supplies the rectified voltage to the electromagnet 53, thereby passing The magnetic force holds the electric drilling equipment to the target object. The AC/DC converter 52 converts the voltage from the external AC power source 50 into a fixed DC voltage (eg, 24 volts) supplied to a control unit for controlling the drive of the electric drill motor 12 .

The triac BCR is provided as a main switching element for turning on/off the electric drill motor 12 from the external AC power source 50 . The opto-triac PHout is connected between the gate terminal and the anode (or cathode) terminal of the triac BCR. A resistor (current detection resistor) R0 is connected in series with the triac BCR to detect the load current flowing through the electric drill motor 12 and the triac BCR.

The control unit to which the DC voltage is applied from the AC/DC converter 52 includes: an on/off control circuit 71, an amplification circuit 72, a smoothing circuit 73, an overload determination circuit 74, an automatic stop/redrive control circuit 75 and a load condition indicating circuit 76.

On/off control circuit 71, the output of which is used to switch the triac BCR ON/OFF control signal.

The amplifier circuit 72 amplifies the voltage across the resistor R0 and outputs the resulting voltage to the smoothing circuit 73 . This amplifier circuit 72 has a small output impedance (substantially zero), and when the voltage across the resistor R0 drops to zero level, it can quickly discharge the capacitor C73 accumulated in the smoothing circuit 73 through the resistor R73. charge. The amplifier circuit 72 has a gain equal to or greater than 1.

The overload determining circuit 74 determines whether the output VL1 of the smoothing circuit 73 exceeds a predetermined reference voltage Vref1 to judge whether the electric drill motor 12 is operating under such a severe overload condition that it may be damaged.

The automatic stop/redrive control circuit 75 uses its output to control the on/off control circuit 71 to automatically stop the power of the electric drill motor 12 when the output VL1 of the overload determination circuit 74 indicates a severe overload condition (or Vref1>VL1). drive, and after a predetermined time elapses from the moment when the drive of the electric drill motor 12 is automatically stopped, the electric drill motor 12 is automatically re-driven.

The load condition indication circuit 76 determines whether the output VL1 of the smoothing circuit 73 exceeds a predetermined reference voltage Vref2 to indicate the load condition of the electric drill motor 1 through LED1 and LED2 . The reference voltage Vref2, which is lower than the reference voltage Vref1 in the overload determining circuit 74, is set so as to invert the output of the comparator OP76 and not be damaged when the electric drill motor 12 is slightly overloaded. LED1 (eg, blue) is on during normal load conditions, while LED2 (eg, red) is on during mild or greater overload conditions. Instead of LED2, two LEDs can be provided to indicate light and severe overload conditions respectively.

In the circuit as described above, the on/off The base current of the transistor Q71 of the ON control circuit 71 flows from the AC/DC converter 52 through the starter switch SWON, whereby the transistor Q71 is turned on, and therefore, the current flows through the photodiode PH21N to turn on the photodiode PH21N. Optically coupled photorelay PH20UT, thereby forming a self-holding circuit for transistor Q71.

When transistor Q71 is turned on, current also flows through photodiode PH1IN connected in series with transistor Q71, turning on phototriac PH1OUT optically coupled to photodiode PH1IN. By turning on the triac BCR, the AC power source 50 is connected to the electric drill motor 12 to be driven. Therefore, the rotation of the electric drill motor 12 is transmitted to the main shaft 18 through the reduction gear mechanism 17, thereby rotating the annular cutter t (see FIGS. 1 and 3).

In this state, when the operator manually operates the handle 39 (see FIG. 1 ) to drive the feed mechanism 20, the annular cutter t moves toward the target while it rotates to form a through hole therethrough.

The load current flowing through the electric drill motor 12 is sensed when the voltage drops across the current sense resistor R0. Then, a voltage proportional to the load current is amplified by the amplifier circuit 72 and supplied to the smoothing circuit 73 . Since the reference voltage Vref1 of the overload determination circuit 74 is set higher than the output voltage VL1 of the smoothing circuit 73 in a normal case where the electric drill motor 12 is not overloaded, the comparator (operational amplifier) OP74 of the overload determination circuit 74 outputs a low level. Therefore, in normal conditions, a low voltage is charged on the capacitor C75 of the auto stop/redrive control circuit 75, so that the base current of the transistor Q75 does not flow and thus remains in the "off" state.

In this state, since the current continuously flows into the photodiode PH1IN of the ON/OFF control circuit 71 through the transistor Q71, the phototriac PH1OUT is kept in the "OFF" state, thereby allowing the triac The thyristor switching element BCR remains in the "on" state.

The reference voltage Vref2 set in the load condition indicating circuit 76 is normally higher than the output VL1 of the smoothing circuit 73, so that the output of the comparator (operational amplifier) OP76 is at a high level. Thus, transistor Q761 and thus LED1 is turned on, while transistor Q762 and thus LED2 is turned off. From the lit LED1 and unlit LED2, the operator can know that the electric drill motor 12 is in a normal state.

On the other hand, when the electric drill motor 12 is overloaded, the load current is increased, so that the voltage across the current detection resistor R0 is increased, thereby increasing the output VL1 of the smoothing circuit 73 . When the output VL1 increases to the reference voltage Vref2 of the load condition indicating circuit 76, the output of the comparator OP76 transitions from high level to low level. This turns transistor Q761 off and turns transistor Q762 on, so that LED1 is off and LED2 is on. With LED1 off and LED2 on, the operator can determine that the drill motor 12 is slightly overloaded, and can therefore adjust the force applied to the operating rod 39 if necessary.

When the electric drill motor 12 is further loaded into a severe overload situation where the electric drill motor 12 may be damaged, the output VL1 of the smoothing circuit 73 increases and the reference voltage Vref1 of the overload determining circuit 74 is higher or higher. At this time, the comparator OP74 of the overload determination circuit 74 outputs a high level, which instantly charges the capacitor C75 through the diode D75 and the resistor R751 (with a small resistance) in the automatic stop/re-drive control circuit 75, thereby making Current flows through resistor R752 and the base emitter of transistor Q75. When transistor Q75 is turned on, the current flowing through photodiode PH1IN of on/off control circuit 71 is shunted to thereby turn off phototriac PH1OUT. When the current of the triac BCR decreases to its holding current or less, it is turned off to cut off the current flowing to the electric drill motor 12 .

When a severe overload condition causes the auto-stop/redrive control circuit 75 to turn off the triac BCR, the voltage drop in the current sense transistor R0 is reduced to zero to reduce the output VL1 of the smoothing circuit 73, thereby The output of the comparator OP74 in the overload determination circuit 74 transitions from high level to low level. Therefore, in the automatic stop/redrive control circuit 75, the base current of the transistor Q75 consists only of the discharge current from the capacitor C75 through the resistor R752. Then, the base current dissipates after a time determined by the discharge time constant, turning off transistor Q75.

In this case, since the self-holding circuit for the transistor Q71 is still formed by the photodiode PH2IN and the photorelay PH2OUT in the on/off control circuit 71, the transistor Q71 is kept in the "on" state. Therefore, when the transistor Q75 is turned off after a predetermined time elapses from the transition of the output from the overload determination circuit 74, the current flows into the photodiode PH1IN through the transistor Q71 again, so that the phototriac PH1OUT is turned on again, And finally the triac BCR is turned on. In this way, power is again supplied to the electric drill motor 12 to rotate the annular cutter t. The discharge time constant of the automatic stop/redrive control circuit 75 is preferably set approximately within a range of, for example, 0.3 to 0.5 seconds. Therefore, after the electric drill motor 12 is overloaded and the current flowing through it is automatically cut off, the power supply to the electric drill motor 12 can be automatically restored in a short time.

Also, since the output VL1 of the smoothing circuit 73 decreases when the electric drill motor 12 removes the overload condition, the output of the comparator OP76 in the load condition indicating circuit 76 changes from a low level to a high level, so that the LED1 is turned on and the LED2 is turned off. open. In this way, the operator can know without mistake that the electric drill motor 12 has released the overload condition, and can therefore operate the operating lever 39 to move the annular cutter t downward again to resume forming a hole through the object.

As described above, according to the electric drill apparatus of the present invention, since the ring cutter having the carbide tip fixed to the cutting edge thereof is used, and the motor capable of rotating the ring cutter at high speed, cutting resistance can be reduced. Therefore, the following operational benefits can be obtained.

(a) The speed reduction mechanism provided between the motor and the main shaft can be designed to use low torque, so that the weight and size of the speed reduction mechanism can be reduced.

(b) The electric drilling device can be fixed to the work piece with less attractive force, thereby reducing the size and weight of the magnetic base which contains the considerable volume and weight of the electric drilling device, thus significantly contributing to the overall size of the electric drilling device and weight reduction.

As will be appreciated from the foregoing, the present invention permits secure fixing of electric drilling equipment to a workpiece while achieving an overall reduction in size and weight of the equipment.

Also, since the automatic motor stop/re-drive device can automatically cut off the current to the motor in an overload situation and automatically re-drive the motor after a predetermined time, the operator does not have to operate a switch for re-driving the motor, thus improving work performance.

In addition, when the drill motor is normally re-driven, the operator can be notified of this, so that the operator can easily know when he can start manipulating the operating rod to feed the drill down.

In addition, since the small-sized electric drill device according to the present invention can increase the rotation speed of the electric drill motor to reduce cutting resistance through the cemented carbide tip fixed on the cutting edge, the electric drill motor can rotate at a high speed, thereby allowing the operator to improve the cutting resistance. Give the amount. Although the motor may be overloaded due to increased feed, an automatic motor stop/re-drive device provided in the drill apparatus prevents the drill motor and ring cutter from being damaged or destroyed due to overload.

Although the electric drilling apparatus according to the present invention has been described with reference to one embodiment, it will be apparent to those skilled in the art that various modifications and substitutions can be made to the present invention.

For example, the control circuit shown in FIG. 4 can be applied to any electric drill apparatus including a vertical arrangement type similar to the small-sized electric drill apparatus shown in FIGS. 1-3.

Also, in the control circuit, instead of an optocoupler, an optional electronic switching device or a mechanical relay device can be employed. Also, instead of the current detection resistor R0 connected in series with the electric drill motor 12, a current transformer may be used to detect the current flowing through the electric drill motor 12. Instead of the triac BCR, a photorelay or a mechanical relay may be used. Any time measuring device, such as a pulse counter, may be used in place of the RC time constant circuit in the auto stop/redrive control circuit 75. In addition, the electric drill motor 12 may be realized by a DC motor, and an SCR, a transistor, or a FET may be used instead of a triac.

Although specific embodiments of the electric drill according to the invention have been described, it is to be understood that the invention is not limited to the illustrated details of these embodiments, but the invention is broadly defined within its spirit and scope as set forth in the appended claims. explain.

Claims (12)

1. electric drilling device with less profile, this equipment comprises:

Main body;

Be installed in the motor on the main body;

Main shaft, it has axis and is used for keeping the annular cutter coaxial with described axis, and this annular cutter has a plurality of teeth of being made by the cemented carbide tip that is fixed on its lower end, so that this annular cutter is cut with high rotating speed;

Reducing gear, it is arranged between motor and the main shaft, is used for by main shaft the driving force of motor being passed to annular cutter;

Feed mechanism, it is used for making main shaft along its axial-movement in response to the operation of manual lever, so that the annular cutter that is installed on the main shaft is advanced with respect to workpiece or bounce back; And

Adhesion base, this adhesion base remains on the bottom of main body, is used for electric drilling device is fixed on workpiece;

Described motor can make annular cutter with suitable high speed rotating, so that carry out the high-speed cutting operation by the annular cutter with cemented carbide tip;

The axis of described main shaft extends along passing to the different direction of the direction of axis of motor axis of rotation of reducing gear with driving force with motor; And

Automatic motor stops/driving mechanism again, and this mechanism comprises:

Main switch element, it is connected in series between motor and the power supply;

Current detector is used to detect the load current of motor of flowing through;

Determining unit is used for determining whether surpass first predetermined reference value by the detected load current of current detector; And

Control module, be used to control the on/off of main switch element, wherein, when determining unit determines that load current surpasses first reference value, control module disconnects main switch element with the flow through electric current of motor of cut-out, and when determining unit determined that load current is reduced to less than first reference value, the predetermined instant of this control module after determining connected main switch element, so that provide electric current from power supply to motor subsequently.

2. electric drilling device as claimed in claim 1 is characterized in that described adhesion base comprises the magnetic bases with magnet.

3. electric drilling device as claimed in claim 1 is characterized in that, the axis perpendicular of the axis of described main shaft and the rotating shaft of motor.

4. electric drilling device comprises:

Motor is used to make annular cutter to rotate;

Main switch element, it is connected in series between motor and the power supply;

Current detector is used to detect the load current of motor of flowing through;

First determining unit is used for determining whether surpass first predetermined reference value by the detected load current of current detector; And

Control module, be used to control the on/off of main switch element, wherein, when determining unit determines that load current surpasses first reference value, control module disconnects main switch element with the flow through electric current of motor of cut-out, and when determining unit determined that load current is reduced to less than first reference value, the predetermined instant of this control module after determining connected main switch element, so that provide electric current from power supply to motor subsequently.

5. electric drilling device as claimed in claim 4 is characterized in that, also comprises:

Main shaft, this main shaft has axis, and the annular cutter axis that the direction different with the direction of the axis of motor axis of rotation extended round the edge that is installed in its front end is rotated.

6. electric drilling device as claimed in claim 5 is characterized in that, the axis perpendicular of the axis of described main shaft and motor axis of rotation.

7. electric drilling device as claimed in claim 4 is characterized in that, described annular cutter comprises by being fixed on its lower end and being fixed on respectively the cutting teeth of making facing to the carbide chip of the position of a plurality of chip areas.

8. electric drilling device as claimed in claim 4 is characterized in that, also comprises:

Second determining unit is used for determining whether surpass second reference value littler than first reference value by the detected load current of current detector; And

The loading condition indicating member is used for indication normal load condition when second determining unit determines that load current does not surpass second reference value, and indicates overload situations when second determining unit is determined load current above second reference value.

9. electric drilling device as claimed in claim 4, wherein:

Described current detector is the fixed resister that is connected in series with motor and main switch element, is used for exporting the voltage of on resistor the corresponding acquisition corresponding with load current; And

First determining unit is used for receiving the voltage corresponding with load current, and with this voltage with and corresponding first reference voltage of first reference value compare whether surpass first reference value so that determine this load current.

10. electric drilling device as claimed in claim 8 is characterized in that,

Described current detector is the fixed resister that is connected in series with motor and main switch element, is used for exporting the voltage that on resistor obtains corresponding with load current; And

Described second determining unit is used for receiving the voltage corresponding with load current, and with this voltage and the second reference voltage comparison corresponding with second reference value, whether surpasses second reference value to determine this load current.

11. electric drilling device as claimed in claim 4 is characterized in that, described control module comprises:

" connection " state self-sustaining unit, it comprises first switch element, is used for when start switch first switch element remained on " connection " state;

Control signal provides the unit, is used to provide " connection " control signal, so that connect main switch element when first switch element is in " connection " state;

The second switch element, it is connected when first determining unit determines that load current surpasses first reference value, so that prevent that control signal from providing the unit and first switch element to be in and irrespectively producing " connection " control signal in " connection " state; And

To determining that by first determining unit load current is reduced to the unit that responds less than first reference value after load current surpasses first reference value, the predetermined instant that is used for after determining disconnects the second switch element.

12. electric drilling device as claimed in claim 4 is characterized in that, described main switch element is a TRIAC, and control module comprises:

" connection " state self-sustaining unit, it comprises first switching transistor, is used for when start switch first switching transistor remained on " connection " state;

Photodiode is used for when first switching transistor is in " connection " state luminous by being provided electric current;

The photoelectricity TRIAC, it is connected between the grid and male or female of TRIAC, and with the photodiode optically-coupled, thereby connect the photoelectricity TRIAC by the light that sends by photodiode, to provide gate current to TRIAC;

The second switch transistor to being determined that by first determining unit load current surpasses first reference value and responds, makes the electric current bypass of photodiode, irrespectively extinguishes this photodiode to be in " connection " state with first switching transistor;

To determining that by first determining unit load current is reduced to the unit that responds less than first reference value after load current surpasses first reference value, the predetermined instant that is used for after determining disconnects the second switch transistor.

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