JP2003340619A - Electric drilling apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-contact depth detecting method of a drilled hole suitable for an electric hand drilling apparatus. <P>SOLUTION: Whether or not a drill bit has been pressed against a workpiece is detected by a position sensor 8 which detects the displacement of a spindle 6. An ultrasonic distance sensor 11 installed in a housing 2 radiates ultrasonic waves toward the workpiece and receives reflected waves of the ultrasonic waves in order to measure the distance to the workpiece. The distance measured at the start of machining by the drill bit (datum position) is memorized. The distance measured during machining (current position) is compared with a datum position to detect a feed distance that is a drilled depth. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric drill for drilling a work, and more particularly to a technique for keeping a constant drilling depth.

[0002]

2. Description of the Related Art There is known a technique in which a depth stopper is attached to an electric drill to facilitate drilling of a predetermined depth (for example, JP-A-63-848).
No. 06 publication). With this technology, an arm (depth stopper) attached to the side of the power tool body parallel to the drill bit
Equipped with. The mounting position of the arm on the power tool body can be adjusted. The mounting position of the arm is adjusted before drilling. As a result, the arm protrusion length from the front surface of the power tool body (drill bit mounting surface) is adjusted to a desired length. As the drilling process progresses, the tip of the arm comes into contact with the workpiece, and the drill bit is prevented from being fed further. Therefore, a hole having a determined depth can be processed. Further, Japanese Patent Laid-Open No. 1-502412 discloses a method of optically measuring the depth of a drill hole.
In this technique, a light source that projects light onto the surface of the work and a light receiver that receives the reflected light from the surface of the work are provided on the main body of the electric tool. When the distance between the power tool body and the work changes, the position of the reflected light observed by the light receiver changes. The distance between the power tool main body and the work can be obtained from the change in the position of the reflected light. When the distance between the electric tool and the work is obtained, the depth of the drill hole is known. Therefore, it is possible to machine a hole having a predetermined depth by stopping the machining based on the measured distance.

[0003]

However, since a large vibration is generated in the electric drill during drilling, the technique using the depth stopper causes problems such as breakage of the arm and durability of the sliding portion. On the other hand, the method of optically measuring the depth of the drill hole requires high assembly accuracy, and
The device itself has the drawback of being expensive. Furthermore, since dust or the like is generated during the drilling process, the optical system such as a lens may become dirty and the distance may not be measured.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to have a simple structure and to have a depth that is stably determined even when vibration or dust occurs. It is to provide an electric drill capable of processing a hole.

[0005]

[Means for Solving the Problem, Action and Effect] In order to solve the above problems, the electric drill according to claim 1 presses the tip of a drill bit attached to the power tool body against the work to mount the power tool body on the work. An electric drill for making a hole in a work by moving in the direction of, a means for driving a drill bit, a means for irradiating a sound wave toward the work, and a means for receiving a sound wave reflected on the work surface. Between the means for measuring the time from the irradiation of the sound wave by the sound wave irradiation means to the reception of the sound wave by the sound wave reception means and between the power tool body and the work when the tip of the drill bit is pressed against the work surface. A means for storing the distance, a means for intermittently operating the sound wave emitting means while the drill bit is being driven, and a timekeeping device based on the distance stored in the storage means. And a means for stopping the machining by the drill bit when the value obtained by subtracting the distance between the power tool body and the work, which is determined from the time counted by the step, reaches the set value. The “distance” referred to here does not have to be the distance itself, but may be a physical quantity capable of obtaining the distance between the power tool main body and the work. For example, it may be the time from the irradiation of the sound wave by the sound wave irradiation means to the reception of the sound wave by the sound wave reception means. The term "stop machining" as used herein means a state in which drilling with a drill bit is not substantially performed. For example, turning off the power to the driving means or shutting off the torque output from the driving means. Equivalent to. When the drive means is an electric motor, the electric motor may be rotated at a slow speed. This is preferable because the reason why the processing is stopped (that is, the hole has reached a predetermined depth) is clearly transmitted to the operator.

In the electric drill having such a structure, the sound wave emitting means is intermittently operated while the drill bit is driven. Therefore, at the time of drilling, the sound wave emitting means intermittently emits the sound wave, and the time counting means measures the time each time the sound wave is emitted. Then, when the value obtained by subtracting the distance between the power tool body and the workpiece, which is determined from the time measured from the distance stored in the storage means (that is, the drilling depth) reaches the set value, the machining with the drill bit is stopped. Therefore, it is possible to automatically machine a hole having a determined depth. Further, since the sound wave is used to measure the distance between the work and the power tool main body, high accuracy is not required in the assembling position of the sound wave irradiating means and the sound wave receiving means. Further, since the sound wave is strong against vibration and the distance can be stably measured even at the site where dust or the like is generated, it is possible to machine a hole having a stably determined depth.

In the above electric drill, a means for detecting that the drill bit is pressed against the work, and a sound wave irradiating means that is activated when the detection means detects that the drill bit is pressed against the work, are used to measure the time. It is preferable to further include a unit for writing the distance between the work and the power tool body, which is determined from the time counted by the unit, in the storage unit. With such a configuration, when the detection unit detects that the drill bit is pressed against the work, the sound wave irradiation unit is activated, the distance between the work and the electric tool body at that time is measured, and the measured distance is measured. Is written in the storage means. Therefore, the position where the drill bit is pressed against the work (that is, the machining start point) is automatically written in the storage means. Therefore, it is not necessary to adjust the machining start point even when the drill bit is replaced.

Further, in the above electric drill, a switch is operated by a person to activate the driving means, and a switch capable of changing the operating speed of the driving means in accordance with the operation amount, and the switch being operated within a predetermined operation amount or less. While operating the sound wave irradiation means intermittently during the operation, means for calculating the moving speed of the power tool body from the time measured by the time measuring means for each irradiation of the sound wave, and the calculated moving speed is smaller than a predetermined value, and It is preferable to further include a unit for writing the distance between the work and the electric tool main body at that time in the storage unit when the operating speed of the drive unit is switched to the full speed. With such a configuration, the operator brings the drill bit close to the work while the switch is slightly pulled (that is, the driving means is in the slow speed operation), and the switch is completely pushed after the drill bit is pressed against the work. When the boring is started by pulling (that is, when the driving means is in the full-speed operation state), the distance between the work and the electric tool main body (machining start point) at that time is stored in the storage means. That is, when performing the drilling process, the operator usually moves the drill bit (that is, the power tool body) toward the processing position.
When the drill bit is pressed against the work, the movement of the power tool body stops. After the tip of the drill bit is pressed against the work, the driving means is operated at full speed to start drilling. Therefore, when the moving speed of the electric tool main body becomes smaller than the predetermined value and the operating speed of the drive means shifts from the slow speed operation to the full speed operation, it is determined that the tip of the drill bit is pressed against the work surface. be able to. The power tool utilizes this fact to automatically store the position of the machining start point in the storage means.

Further, in the above electric drill, a switch operated by a person and a sound wave irradiation means are operated when the switch is operated, and the distance between the work and the electric tool main body determined by the time counted by the time measuring means is set. Means for writing to the storage means may be further provided. In such a configuration, when the operator presses the drill bit against the work and operates the switch, the distance (working start point) between the work and the power tool body when the drill bit is pressed against the work is stored in the storage means. It Therefore, it is possible to easily readjust the machining start point when exchanging the drill bit.

In this case, it is preferable that the switch is a switch for activating the driving means, and the writing means is activated only when the first switch operation is performed after the power is turned on. With this configuration, the switch for adjusting the machining start point and the switch for activating the drive means can be made common.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The technique of the present invention can be suitably implemented in the modes described below. (Mode 1) In the above electric drill, the sound wave emitting means emits ultrasonic waves and the sound wave receiving means receives ultrasonic waves. This is because the ultrasonic distance sensor is not easily affected by dust or the like, has a simple structure, and has high reliability against vibration. (Mode 2) In the electric drill, a switch for setting a set value is added. By operating the setting switch, it becomes possible to machine a hole having a desired depth. (Mode 3) In the above electric drill, the set value is set by the manufacturer. Processing has started and the depth of the hole is first
When the setting value becomes, the drilling process is stopped and the driving means is operated at a very low speed. When the switch for driving the driving means is operated within a predetermined time after the slow speed operation, drilling is restarted by the second set value set by the manufacturer. (Mode 4) In the electric drill according to claim 2, the drill bit is attached to the electric tool main body so as to be able to move back and forth in the axial direction, and the detection means detects that the drill bit has retreated in the axial direction. It is a sensor for detecting. This sensor includes a position sensor (proximity sensor) that detects displacement,
A force sensor that detects the reaction force can be used. (Mode 5) In the above electric drill, when a value obtained by subtracting the distance between the electric tool main body and the workpiece determined from the time measured by the time measuring means from the distance stored in the storage means reaches a set value, A display device that displays the depth of the hole, or an alarm device that alerts when the depth of the hole reaches a predetermined value by sound or light is provided. In such a configuration, the operator can know that the depth of the hole has reached the predetermined value by the display of the display device or the alarm of the alarm device, and can decide whether or not to continue the drilling process. In addition, the display device and the alarm device may be replaced with the processing stopping means, or
It can be provided in combination with the processing stopping means.

[0012]

Embodiment An embodiment of the present invention will be described with reference to FIGS. 1 is a partial cross-sectional side view of a hand-held power drill 1 embodying the power tool of the present invention, FIG. 2 is a plan view of the drill, FIG. 3 is a partial front view of the drill, and FIG. 4 is a part of the drill. FIG. Reference numeral 2 in FIGS. 1 to 3 denotes a housing in which a motor 3 as a drive source is housed and fixed. A pinion gear 3b is formed on a shaft 3a of the motor 3 (supported by bearings 4a and 4b), and gear trains 5a and 5b mesh with the pinion gear 3b. The gear trains 5a and 5b constitute a speed reduction mechanism and are connected to a speed change / vibration mechanism (not shown) so that the spindle 6 is finally driven. Shaft 3a
A spindle 6 (also referred to as a main shaft) pivotally supported by the bearings 4c and 4d at a position parallel to is provided with a chuck 6a for holding a drill bit (not shown) at its tip. The spindle 6 is supported so as to be slightly movable in the axial direction, and a spring (disc spring) 7 urges the spindle 6 in a direction in which the chuck 6a and the drill bit are projected. A magnet (not shown) is arranged on the rear surface (on the side of the motor 3) of the gear 5b mounted on the spindle 6. A position sensor 8 for detecting displacement of the spindle 6 in the axial direction is arranged at a position facing the back surface of the gear 5b. The position sensor 8 is a magnetic sensor using a Hall element. When the spindle 6 is pressed from the chuck 6a side to the motor 3 side and moves in the axial direction, the gear 5b approaches the position sensor 8. Therefore, the position sensor 8 detects the magnetic field of the magnet arranged in the gear 5b and changes its output signal. As a result, movement of the spindle 6 in the axial direction is detected.
The position sensor 8 is shown in FIG. 4 (in this figure, the spring 7 is bent by an external force in the direction of the arrow).
As is well shown in FIG. 3, it is supported at an optimum position (a position close to the gear 5b mounted on the spindle 6 in this example) by a mounting member 8a mounted on the housing 2.

The housing 2 is integrally formed with a handle portion 2a. The handle portion 2a is provided with a main switch 8 for turning on / off power supply to the motor 3. The main switch 8 is a switch with a shift function that shifts the number of rotations of the motor 3 according to the amount of operation by the operator (the amount by which the switch is pulled). Therefore, when the operator aligns the drill bit, it is possible to reduce the amount of operation of the main switch 8 and bring the drill bit closer to the work while rotating the drill bit at a very low speed. A power cable extends downward from the lower end of the handle portion 2a. A control device 10 is attached to the upper portion of the housing 2. Electronic components such as a microcomputer and a drive circuit are mounted on the control board 10a of the control device 10. At the upper position of the housing 2, a transmitter (speaker) that emits ultrasonic waves toward the work located in front of the chuck 6a and a receiver (microphone) that receives the reflected wave from the work are further provided. The ultrasonic distance sensor 11 is attached. The control device 10 takes in the output of the ultrasonic distance sensor 11 and measures the propagation time of the ultrasonic waves to calculate the distance to the work, and further takes in the output of the position sensor 8 to detect the displacement of the spindle 6. Determine whether the drill bit has been pressed against the workpiece. Also,
A known rotation sensor 12 such as a rotary encoder connected to the control device 10 is installed on the opposite output side of the motor 3, and the rotation speed is detected via the rotation sensor 12.

Next, the circuit configuration of the electric drill 1 will be described with reference to FIG. A motor 3 connected to an output stage (deceleration mechanism, vibration mechanism, and spindle) 13 of the electric drill 1 is connected to a drive circuit 14. The drive circuit 14 is the control device 10.
The power supply control of the motor 3 is performed by the phase control method. The control device 10 further includes a rotation sensor 1
2, the position sensor 8 and the ultrasonic distance sensor 11 are connected to each other so that the rotational speed of the motor 3, the axial displacement of the spindle 6, and the distance to the work can be detected. Electric power is supplied to the control device 10 and the drive circuit 14 from the outside through the power supply circuit 15. The microcomputer mounted on the control board of the control device 10 is a microcomputer in which CPU, ROM, RAM and I / O are integrated into one chip. In the ROM of this microcomputer, the displacement of the spindle 6 in the axial direction is detected, the distance from the housing 2 to the work is measured, and further, the drive circuit 14 is operated according to the set operating conditions.
A control program for controlling the operation of the motor 3 via the is stored.

Next, the operation of the electric drill 1 will be described with reference to the flowcharts shown in FIGS. 6 and 7. It is assumed that an appropriate drill bit is attached to the chuck 6a of the electric drill 1. Now, when the operator turns on the main switch 8 that is a trigger, the control program of the control device 10 is activated. When the trigger-on is recognized, the counter and the memory are initialized, and the previously selected / input drilling depth (for example, 10 cm) is set as the set value D1 (step S1). Set value D1
May be preset by the manufacturer, or may be set by the user using a separately provided setting switch or the like. Then, the supply of electric power to the motor 3 is started to rotate the motor 3 (step S2).

Next, referring to the output of the position sensor 8, it is judged whether or not the spindle 6 is retracted in the axial direction, that is, whether or not the drill bit is pressed against the work. The determination processing is looped and waits (step S3). In the case of Yes in which it is determined that the drill bit is pressed against the work in step S3 and is positioned at the machining start point, the process proceeds to the next step, and the distance to the work is measured via the ultrasonic distance sensor 11 ( Step S4). This distance measurement is performed by the ultrasonic distance sensor 11
It measures the propagation time until the ultrasonic pulse emitted from the device propagates in the air, is reflected on the surface of the work, and is received by the sensor again. Then, the obtained value is converted into a distance, and the origin position (processing start point) D2 is stored in the memory (step S5).

After steps S4 and S5, the tip of the drill bit is pressed against the work and the drilling is started. At any time during the drilling process, the ultrasonic distance sensor 11
To the workpiece is measured (step S7). Then, the obtained value is converted into a distance, and the current position D3 is detected (step S8). Current position D3 detected at this time
And the origin position D2 are compared, and it is judged whether or not the distance between the two, that is, the moving distance of the bit (depth of the hole) has reached the set value D1 (step S9), and if not reached, drilling is continued. , The process returns to step S7. Step S
In 9 it is judged that the depth of the hole has reached the set value D1 Yes
In this case, since the bit has reached the required cutting distance and the machining has been completed, the output of the motor 3 is reduced to make the motor run at a slow speed (step S10), and the process proceeds to the continuation / end process described below.

Next, the continuation / end processing will be described with reference to the flowchart of FIG. The purpose of this process is to facilitate the continuation of drilling by switching the set value to a small value based on the trigger operation when the drilling of the depth set in step S1 is completed. In addition, it is possible to avoid a decrease in work efficiency associated with motor stop / restart by determining whether or not additional machining for deepening the hole is required while the motor 3 is operating at a slow speed. One purpose. First, in step S11, it is determined whether the trigger state is OFF, and if the trigger is ON, N
In the case of o, the slow speed operation of the motor 3 is continued, and this determination processing is looped to stand by. On the other hand, if the trigger is off and Yes, the power of the motor 3 is turned off (step S
12), the timer is started (step S13). It is determined whether or not the timer has reached a predetermined time (for example, 1 second) (step S14). If the trigger-off state is No for more than 1 second, all the processing is terminated as it is.

On the other hand, if it is less than 1 second, the trigger is continuously monitored and it is judged whether or not the trigger is turned on (step S15). When the trigger is turned on, the process goes to the hole machining addition mode, the origin position (machining start point) D2 is replaced with the current position D3, and a new drilling depth (for example, 1 cm) is set as the set value D1 (step S16). Then, after the power of the motor 3 is turned on (step S17), the process is returned to step S7. Hereinafter, the above steps are repeated. In this way, the holes can be machined gradually deeper in steps of 1 cm.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. For example, in the above-described embodiment, the origin position (machining start point) is stored in the memory by detecting that the spindle 6 has retracted in the axial direction by the position sensor 8. However, the origin position storage method is as follows. It is not limited to the method. For example, the origin position can be stored in the memory by the procedure shown in FIG. That is, when the trigger is turned on, first, the distance is measured (step S18), and the rotation speed of the motor is equal to or lower than a predetermined value (that is, the motor is rotating at a very low speed).
It is determined whether or not (step S19). When the number of rotations of the motor exceeds the predetermined value [NO in step S19], it is determined that it is not necessary to store the processing start point, and the processes of steps S20 to S22 are skipped. If the rotation speed of the motor does not exceed the predetermined value [YES in step S19], it is determined whether the moving speed of the electric drill body is less than the predetermined value (step S20). The moving speed of the electric drill main body is calculated by the time interval at which the distance measurement in step S18 is performed and the change in the distance measured by each distance measurement. Since the moving speed of the electric drill main body cannot be calculated at the stage when the first distance measurement is performed, the determination in step S20 is programmed to be always NO. When the moving speed of the electric drill body exceeds a predetermined value [NO in step S20],
If it is judged that the drill bit is not pressed against the work and the movement of the electric drill body has not stopped, step S
Return to 18. On the other hand, when the moving speed of the electric drill body is less than the predetermined value [YES in step S20],
When it is determined that the drill bit has been pressed against the work and the movement of the electric drill body has stopped, the process proceeds to step S21.
In step S21, it is determined whether or not the motor rotation speed has changed to full speed rotation. If the motor has not changed to full-speed rotation [NO in step S21], it is determined that drilling has not started, that is, the drill bit has not been pressed against the work, and the process returns to step S18. On the other hand, when the motor speed is full speed [YES in step S21], it is determined that drilling has been started, that is, the drill bit is pressed against the workpiece, and distance measurement is performed. The measurement result is stored in the memory as the origin position (step S22). In this way, the origin position can be stored in the memory without a position sensor for detecting the displacement of the spindle by bringing the drill bit closer to the work while being rotated at a very low speed.

The origin position may be measured by first turning on the main switch 8 after inserting the power plug into the outlet. That is, the microcomputer of the control device 10 is programmed to operate the ultrasonic distance sensor 11 to perform distance measurement when the main switch is first turned on after the power is turned on. Therefore, with this method, plug the power plug into the outlet, press the drill bit against the work or wall,
The origin position is measured and stored by simply turning on the main switch. In this method, when the main switch is turned on for the second time, the normal position (that is, the drilling process) is performed without initializing the origin position.

The technical elements described in the present specification or the drawings exert technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Further, the technique illustrated in the present specification or the drawings achieves a plurality of purposes at the same time, and achieving the one purpose among them has technical utility.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional side view of an electric drill according to this embodiment.

FIG. 2 is a plan view of the electric drill.

FIG. 3 is a partial front view of the electric drill.

FIG. 4 is a partially enlarged view of the electric drill.

FIG. 5 is a block diagram explaining a circuit configuration of the electric drill.

FIG. 6 is a flow chart for explaining a drilling depth detection operation of the same.

FIG. 7 is a flow chart for explaining a drilling depth detection operation of the same.

FIG. 8 is a flowchart illustrating another method for storing the origin position.

[Explanation of symbols]

1: Electric drill (power tool) 2: Housing 3: Motor 8: Position sensor 10: Control device 11: Ultrasonic distance sensor 12: Rotation sensor

Claims (5)

[Claims] 1. An electric drill for punching a work by pressing the tip of a drill bit attached to a power tool body against a work and moving the power tool body in the direction of the work. The power drill drives the drill bit. Means, a means for radiating a sound wave toward the work, a means for receiving the sound wave reflected on the work surface, and a time period from the sound wave being irradiated by the sound wave irradiating means to the sound wave being received by the sound wave receiving means. Means for measuring the time, means for storing the distance between the power tool body and the work when the tip of the drill bit is pressed against the work surface, and intermittent operation of the sound wave irradiation means while the drill bit is driven And the distance stored in the storage means, the distance between the power tool body and the workpiece determined by the time measured by the time measuring means is subtracted. Electric drill, characterized in that it and a means for stopping the processing by the drill bit when the value reaches a set value. 2. A means for detecting that the drill bit has been pressed against a work, and a sound wave irradiating means that is activated when the detection means detects that the drill bit has been pressed against the work, and the time measuring means measures the time. The electric drill according to claim 1, further comprising: a unit that writes a distance between the work and the power tool body, which is determined by the time taken, in a storage unit. 3. A switch which is operated by a person to activate the drive means and which can change the operating speed of the drive means in accordance with the operation amount, and intermittently while the switch is operated at a predetermined operation amount or less. The means for activating the sound wave irradiation means to calculate the moving speed of the power tool body from the time measured by the time measuring means for each irradiation of the sound wave, and the calculated moving speed is smaller than the predetermined value and the driving means is operated. The electric drill according to claim 1, further comprising: a unit that, when the speed is switched to the full speed, writes the distance between the work and the power tool body at that time in the storage unit. 4. A switch operated by a person and a sound wave irradiation means is operated when the switch is operated, and a distance between a work and a power tool main body, which is determined by a time measured by the time measuring means, is written in a storage means. The electric drill according to claim 1, further comprising means. 5. The switch is a switch for activating a driving means, and the writing means is a switch after the power is turned on.
The electric drill according to claim 4, wherein the electric drill is activated only when a switch operation is performed a second time.