WO2021039186A1

WO2021039186A1 - Portable machining tool

Info

Publication number: WO2021039186A1
Application number: PCT/JP2020/027865
Authority: WO
Inventors: 淳井戸田
Original assignee: 日東工器株式会社
Priority date: 2019-08-28
Filing date: 2020-07-17
Publication date: 2021-03-04
Also published as: JP7182721B2; AU2020338309B2; JPWO2021039186A1; DE112020004086T5; CN114080297A; AU2020338309A1; GB2600572B; GB2600572A

Abstract

[Problem] To provide a portable machining tool with which it is possible to detect floating of an electromagnet more appropriately even when the thickness of a workpiece to be magnetically attracted by the electromagnet is different. [Solution] A portable machining tool 1 is provided with: an electromagnet 12 for fixing a machining tool body 10 with respect to a workpiece; a magnetic sensor 42 arranged around the electromagnet; an electric motor 20 for rotationally driving an annular cutter 16; and a control unit 48 for controlling the electromagnet 12 and the electric motor 20. The control unit 48 sets a normal operation range on the basis of an output value from the magnetic sensor 42 during operation of the electromagnet 12 and before driving the electric motor 20 to start a machining task with the annular cutter 16. Furthermore, when the output value from the magnetic sensor 42 after the start of the machining task is out of the normal operation range, the control unit 48 determines that the electromagnet 12 has floated from the workpiece and stops driving of the electric motor 20.

Description

Portable machine tool

The present invention relates to a portable machine tool, and more specifically, to a portable machine tool in which a machine tool body is fixed to an object to be machined by an electromagnet.

There is a portable machine tool such as a drilling machine that is carried to the work site to process the work piece. Such a portable machine tool is fixed to the work piece by various methods, but in consideration of ease of handling and convenience, it is fixed to the work piece by magnetic adsorption by an electromagnet. There is something that I did. (Patent Documents 1 and 2)

Magnetic attraction by an electromagnet is usually designed to be a sufficiently large force, but the reaction force received during machining work and other external forces applied to the machine tool body cause the machine tool body to lift from the work piece. There is. Then, a gap is created between the electromagnet and the work piece, and the magnetic attraction force of the electromagnet sharply decreases, making it impossible to fix the portable machine tool to the work piece, causing the portable machine tool to fall or fall. There is a risk of This is especially dangerous if the portable machine tool falls while a machining tool such as a drill or an annular cutter is being rotationally driven. Therefore, in the drill device shown in Patent Document 2, a Hall element for measuring the magnetic flux generated from the electromagnet is provided, and it is determined that floating occurs when the output voltage V of the Hall element exceeds a predetermined threshold value Va. The rotation of the drill motor and feed motor is stopped.

Japanese Unexamined Patent Publication No. 2014-231129 Jikkenhei 3-126512

However, the magnitude of the magnetic flux density around the electromagnet when the electromagnet is magnetically attracted to the work piece changes depending on the thickness and material of the work piece. Therefore, when the predetermined threshold value is set to a relatively large value based on the case where the workpiece is relatively thick or the material has relatively strong magnetism, it is relatively thin or compared. When the work piece is magnetically attracted to a work piece having weak magnetism, it becomes impossible to properly detect the floating, and conversely, it is based on the case where the work piece is relatively thin or the material has relatively weak magnetism. If a predetermined threshold value is set to a relatively small value, it may not be possible to properly detect the floating when magnetically attracted to a work piece having a relatively thick or relatively strong magnetism. There is.

Therefore, an object of the present invention is to provide a portable machine tool capable of appropriately detecting the lifting of an electromagnet even if the plate thickness and material of the work piece magnetically attracted by the electromagnet are different.

That is, the present invention
Machine tool body and
An electromagnet attached to the machine tool body and fixing the machine tool body to the work piece,
A magnetic sensor arranged around the electromagnet and
A control unit designed to control the operation of the electromagnet,
A drive unit for driving a machining tool attached to the machine tool body so as to perform machining work on the workpiece.
With
The magnetic sensor after the control unit sets the normal operating range based on the output value of the magnetic sensor while the electromagnet is operating and before the machining work by the drive unit is started, and after the machining work is started. Provided is a portable machine tool in which it is determined that the electromagnet is lifted from the workpiece when the output value of is out of the normal operating range.

In the portable machine, the normal operating range is set based on the output value of the magnetic sensor measured before the electromagnet is operating and the electric motor is driven to start the machining work. An appropriate normal operating range can be set according to the thickness and material of the work piece to which the electromagnet magnetically attracts. As a result, it is possible to appropriately detect the determination of the lift of the electromagnet even if the plate thickness and material of the workpiece are different.

Specifically, the magnetic sensor is adapted to detect the magnetic flux density in the magnetic circuit of the electromagnet formed through the workpiece, and the output value is a value indicating the magnitude of the magnetic flux density. Can be done.

Also,
The normal operating range is a range in which the floating determination reference value determined based on the magnitude of the output value is set as the lower limit value.
When the output value of the magnetic sensor after starting the machining work becomes less than the lift determination reference value, the control unit can determine that the electromagnet has lifted from the workpiece.

Also,
The control unit is designed to detect the supply voltage to the electromagnet.
The control unit can set the normal operating range based on the output value of the magnetic sensor and the supply voltage before the processing work by the driving unit is started while the electromagnet is operating. ..

In this case, when the supply voltage changes during the machining operation, the control unit can reset the normal operating range based on the magnitude of the supply voltage.

This makes it possible to reduce the influence of changes in the magnetic flux density due to changes in the power supply voltage and to make the electromagnets lift more stably.

Also,
When the output value of the magnetic sensor is equal to or higher than a predetermined first threshold value while the electromagnet is operating and before the processing work by the driving unit is started, the control unit raises the normal operating range by a predetermined first floating. Set the judgment reference value to the lower limit and set it to the lower limit.
When the output value is less than the first threshold value and greater than or equal to a predetermined second threshold value smaller than the first threshold value, the control unit sets the normal operating range smaller than the first floating determination reference value. It is possible to set a predetermined second lift determination reference value in a range set as a lower limit value.

In this case, when the output value of the magnetic sensor is less than the second threshold value while the electromagnet is operating and before the processing work by the driving unit is started, the driving of the driving unit cannot be started. can do.

Also,
It also has a display unit that displays the status of the portable machine tool.
When the output value of the magnetic sensor is equal to or higher than the first threshold value while the electromagnet is operating and before the processing work by the driving unit is started, and when it is less than the first threshold value and equal to or higher than the second threshold value. And when it is less than the second threshold value, it is possible to display differently.

Hereinafter, embodiments of the portable machine tool according to the present invention will be described with reference to the attached drawings.

It is a side view of the portable machine tool which concerns on one Embodiment of this invention. It is sectional drawing of the portable machine tool of FIG. It is a functional block diagram of the portable machine tool of FIG. It is a 1st flowchart which shows the operation of the portable machine tool which concerns on one Embodiment of this invention. It is a 2nd flowchart which shows the operation of the portable machine tool which concerns on one Embodiment of this invention. It is a 3rd flowchart which shows the operation of the portable machine tool which concerns on one Embodiment of this invention. It is a flowchart which shows the operation concerning the threshold reset among the operations of the portable machine tool which concerns on another Embodiment of this invention.

As shown in FIG. 1, the portable machine tool 1 according to the embodiment of the present invention includes a machine tool main body 10 and an electromagnet 12 attached to the lower side of the machine tool main body 10. A battery 14 serving as a main power source for the portable machine tool 1 is detachably attached to the rear of the machine tool main body 10. As shown in FIG. 2, the machine tool main body 10 includes a machining tool mounting portion 18 to which an annular cutter 16 (machining tool) can be detachably attached, and the machining tool mounting portion 18 is rotationally driven in the machine tool main body 10. An electric motor 20 (driving unit) for the purpose is provided. The machining tool mounting portion 18 and the electric motor 20 are drive-connected via a gear mechanism 22 composed of a plurality of gears. As shown in FIG. 1, a lever 24 is attached to the machine tool main body 10, and by pivoting the lever 24, the machining tool attachment portion 18 is moved up and down together with the annular cutter 16. As shown in FIG. 2, the electromagnet 12 has a ring-shaped second coil 30 as well as a ring-shaped first coil 26. When the portable machine 1 is placed on the magnetic material and the power from the battery 14 is supplied to the first coil 26 and the second coil 30, the magnetic attraction generated by the electromagnet 12 causes the machine main body. 10 is fixed to a work piece which is a magnetic material. The portable machine tool 1 is processed by pressing an annular cutter 16 rotationally driven by an electric motor 20 against the workpiece while the machine tool body 10 is fixed to the workpiece by an electromagnet 12. It is a drilling machine designed to perform processing work on objects.

As shown in FIG. 1, on the side surface of the machine tool main body 10, a motor drive switch 34 for starting the drive of the electric motor 20, a motor stop switch 36 for stopping the drive of the electric motor 20, and an electromagnet 12 An electromagnet switch 38 for starting and stopping the operation of the motor is arranged. A lighting switch 40 is also arranged on the side surface of the machine tool main body 10. The lighting switch 40 is used to turn on and off a lighting device (not shown) arranged on the front lower surface of the machine tool main body 10. All of these

switches

34, 36, 38, and 40 are push-button momentary switches that turn on only while they are pressed and return to the off state when they are released. The machine tool main body 10 is further provided with an LED display unit 41 for indicating the state of the portable machine tool 1 to an operator.

As shown in FIG. 2, a magnetic sensor 42 is attached to the electromagnet 12. The magnetic sensor 42 measures the magnitude of the magnetic flux density in the magnetic circuit of the electromagnet 12 formed around the electromagnet 12 through the workpiece.

The portable machine tool 1 has a control circuit board 46 in the machine tool main body 10, and the control circuit board 46 is provided with a control unit 48 (FIG. 3) for controlling an electric motor 20, an electromagnet 12, and the like. ing. When the battery 14 is attached to the machine tool main body 10, electric power is supplied from the battery 14 to the control unit 48 via the control power supply circuit 50 to start the control unit 48. The control unit 48 drives the electric motor 20 and operates the electromagnet 12 according to the operating state of the motor drive switch 34, the motor stop switch 36, and the electromagnet switch 38, and the operating state of the portable machine tool 1 at that time. Control. When the electric motor 20 is being driven, the control unit 48 transmits a control signal to the motor control unit 52 to control the rotation speed of the electric motor 20. At this time, the control unit 48 detects the amount of current flowing through the electric motor 20 by the motor current detection unit 54 and monitors the load status of the electric motor 20. When the electromagnet 12 is being operated, the control unit 48 controls the electric power supplied to the first coil 26 and the second coil 30 via the coil control circuit 56. Since the first coil 26 and the second coil 30 are connected in series, the electric power supplied to the first coil 26 and the second coil 30 is usually the same. The coil disconnection detection circuit 58 detects the disconnection of the first coil 26 and the second coil 30 by detecting the current flowing through the first coil 26 and the second coil 30. When a disconnection of the first coil 26 or the second coil 30 is detected, the control unit 48 stops the control and lights the LED display unit 41 to notify the user that the

coils

26 and 30 are disconnected. Further, the control unit 48 remembers that the

coils

26 and 30 are disconnected, and turns on the LED display unit 41 when the battery 14 is once disconnected and then reconnected and the control of the control unit 48 is resumed. It is also designed to notify the user that the

coils

26 and 30 are broken.

The control circuit board 46 is further provided with a power supply voltage detection circuit 60 for detecting the voltage (power supply voltage) of the battery 14 connected to the machine tool main body 10.

The operation of the portable machine tool 1 will be described below based on the flowcharts of FIGS. 4 to 6. As shown in FIG. 4, when the battery 14 is attached to the machine tool main body 10 and power is supplied to the control unit 48, the control by the control unit 48 is started (S10). First, the control unit 48 determines whether or not the electromagnet switch 38 is not pressed and is in the OFF state (S12). In the case of the OFF state, when the electromagnet switch 38 is pressed to change from the OFF state to the ON state (S18), the control unit 48 starts the operation of the electromagnet 12 (S20). When the electromagnet 12 is activated, the portable machine tool 1 is fixed to the workpiece by the magnetic attraction force of the electromagnet 12.

When the electromagnet switch 38 is not in the OFF state when the control is started, that is, when the electromagnet switch 38 is pressed and is in the ON state (S12), the control unit 48 does not start the operation of the electromagnet 12, and the operation of the electromagnet 12 is not started. When the state continues for 5 seconds (S14), the LED display unit 41 is blinked to display a warning (S16). As a result, when the battery 14 is installed while the operator accidentally presses the electromagnet switch 38, the operation of the electromagnet 12 is started at the same time as the control is started to prevent unexpected magnetic attraction. .. When the operator releases the electromagnet switch 38 and the electromagnet switch 38 is turned off, the warning display on the LED display unit 41 is canceled and the control proceeds to step S18. Even if the motor drive switch 34 is turned on before the operation of the electromagnet 12 is started, the control unit 48 does not start driving the electric motor 20.

When the electromagnet 12 is activated, as shown in FIG. 5, the control unit 48 measures the magnetic flux density around the electromagnet 12 by the magnetic sensor 42 (S22). When the output value of the magnetic sensor 42 indicating the magnitude of the measured magnetic flux density is equal to or higher than the predetermined first threshold value X [V] (S24), the control unit 48 is a member of the member to which the electromagnet 12 is magnetically attracted. It is determined that the plate thickness is α [mm] or more (S26), and the blue color of the LED display unit 41 is used to show the operator that the plate thickness is sufficient and the magnetic attraction force of the electromagnet 12 is sufficient. The LED is turned on (S28). When the output value of the magnetic sensor 42 is less than X [V] (S24) and greater than or equal to a predetermined second threshold value Y [V] smaller than X (S30), the control unit 48 has a plate thickness of α [mm]. ] And β [mm] or more (S32), and the LED display unit 41 is used to show the operator that the plate thickness is slightly thin and the magnetic attraction force of the electromagnet 12 is slightly small, although it is within the safe operating range. Turn on the yellow LED (S34). Here, the safe operating range refers to the range of the magnetic flux density at which a magnetic attraction force having a magnitude that allows the processing work by the portable machine tool 1 to be performed without danger is generated. In the state where the blue LED or the yellow LED is lit, when the motor drive switch 34 is pressed to turn on (S38), the control unit 48 starts driving the electric motor 20 (S40).

When the output value of the magnetic sensor 42 is less than Y [V] and is not within the safe operating range (S30), the control unit 48 indicates that the plate thickness is too thin to obtain a sufficient magnetic attraction force. A red LED is lit on the LED display unit 41 to indicate the above (S36). In this state, even if the motor drive switch 34 is pressed to turn on, the control unit 48 does not start driving the electric motor 20.

While the electromagnet 12 is operating but the electric motor 20 is not driving, press and hold the electromagnet switch 34 to maintain the ON state for 2 seconds or longer (S42, S44), and then stop pressing and holding the electromagnet switch 34 to stop the electromagnet. When the switch 34 is turned off (S46), the control unit 48 stops the operation of the electromagnet 12 (S48). As a result, a series of controls is completed (S50).

When the drive of the electric motor 20 is started in step S40, the control unit 48 controls the control shown in FIG. 6 for detecting the lifting of the portable machine tool 1 during the machining work and the change in the plate thickness of the workpiece. To execute. First, the control unit 48 confirms whether the plate thickness of the work piece is determined to be α [mm] or more (S52). When it is determined that the plate thickness is α [mm] or more, the control unit 48 compares the output value of the magnetic sensor 42 with the predetermined first lift determination reference value A [V] (S54). The first lift determination reference value A [V] is a lower limit value of the normal operation range set when the plate thickness is α [mm] or more, and is smaller than the first threshold value X [V]. Here, the normal operating range is a range of magnetic flux densities that can be regarded as the portable machine tool 1 not being lifted from the work piece and being properly fixed to the work piece during the machining work. When the output value of the magnetic sensor 42 is less than the first lift determination reference value (A [V]), that is, it is out of the normal operating range, the control unit 48 determines that the electromagnet 12 has lifted from the workpiece. In order to show this to the operator, the red LED of the LED display unit 41 is turned on (S56), and the driving of the electric motor 20 is stopped (S58). After the electric motor 20 is stopped, the control by the control unit 48 returns to the above step 22.

In step S54, when the output value of the magnetic sensor 42 is equal to or higher than the first lift determination reference value (A [V]), that is, within the normal operating range, the control unit 48 has not lifted the electromagnet 12 from the workpiece. Judging, the driving of the electric motor 20 is continued. When the motor stop switch 36 is pressed to turn on (S66) or the electromagnet switch 38 is pressed to turn on (S68) while the electric motor 20 continues to be driven, the control unit 48 The drive of the electric motor 20 is stopped (S58), and the control returns to the control in step S22. When both the motor stop switch 36 and the electromagnet switch 38 are not pressed and are in the OFF state, the magnetic flux density around the electromagnet 12 is measured again by the magnetic sensor 24 (S70), and the control returns to the control in step S52.

When it is determined that the plate thickness is not α [mm] or more, that is, less than α [mm] and β [mm] or more (S52), the output value of the magnetic sensor 42 is determined to be a predetermined second floating determination. Compare with the reference value B [V] (S60). The second lift determination reference value B [V] is the lower limit value of the normal operation range when the plate thickness is less than α [mm] and β [mm] or more, and is the second threshold value Y [V] and the first lift. It is a value smaller than the judgment reference value A [V]. When the output value of the magnetic sensor 42 is less than the second lift determination reference value (B [V]), that is, outside the normal operating range (S60), the control unit 48 determines that the electromagnet 12 has lifted from the workpiece. In order to show it to the operator, the red LED of the LED display unit 41 is turned on (S56), and the driving of the electric motor 20 is stopped (S58). When the output value of the magnetic sensor 42 is B [V] or more (S60), the control unit 48 compares the output value of the magnetic sensor 12 with the first threshold value X [V] (S62). When the output value of the magnetic sensor 42 is X [V] or more, it is determined that the plate thickness has increased to α [mm] or more (S64). This is because the plate thickness was initially less than α [mm], but it seems that the overall plate thickness has increased to α [mm] or more by attaching another plate under the work piece in the middle. I assume the case. After that, the process proceeds to step 66, and the above-mentioned control is performed.

In this way, in the portable machine tool 1, the normal operating range is set based on the output value of the magnetic sensor 42 while the electromagnet 12 is operating and before the machining work by the electric motor 20 is started. .. Therefore, an appropriate normal operating range can be set according to the plate thickness of the work piece to which the electromagnet 12 magnetically attracts, and it becomes possible to more stably and appropriately determine whether the electromagnet 12 is lifted. In addition, when the electromagnet 12 slides sideways without lifting from the work piece, the output value of the magnetic sensor 42 also decreases when the electromagnet 12 moves from a relatively thick portion to a relatively thin portion. However, even if the output value of the magnetic sensor 42 deviates from the normal operating range, the control unit 48 determines that the electromagnet 12 has been lifted. That is, the determination that the surface has floated in the present application may include the determination that the skidding has occurred as described above.

In another embodiment of the present invention, after the measurement of the magnetic flux density by the magnetic sensor 42 of S22 of FIG. 5 and S70 of FIG. 6, the resetting of the threshold value based on the power supply voltage shown in FIG. 7 is executed. ing. Other controls are the same as in the above embodiment.

In resetting the threshold value based on the power supply voltage, first, the supply voltage to the electromagnet 12, that is, the voltage of the battery 14 (power supply voltage) is measured (S100), and the measured power supply voltage is compared with the predetermined threshold value Z [V]. (S102). When the power supply voltage is larger than Z [V], each threshold value or reference value (X, Y, Z, A, B) is increased by a predetermined increase / decrease value (a, b, c, d, e). Change (S104). That is, a is added to X, b is added to Y, c is added to Z, d is added to A, and e is added to B. Then, the measured power supply voltage is compared with the changed Z [V] (S106), and when the power supply voltage is Z [V] or more, each threshold value or reference value (X, Y, Z, A, B) is set. The value is changed to a larger value by a predetermined increase / decrease value (a, b, c, d, e) (S104). This is performed until the measured power supply voltage becomes less than the changed Z [V]. When the power supply voltage is Z [v] or less in S102, each threshold value or reference value (X, Y, Z, A, B) is reduced by a predetermined increase / decrease value (a, b, c, d, e). Change (S108). That is, a is subtracted from X, b is subtracted from Y, c is subtracted from Z, d is subtracted from A, and e is subtracted from B. Then, the measured power supply voltage is compared with the changed Z [V] (S110), and when the measured power supply voltage is Z [V] or less, each threshold value or reference value (X, Y, Z, A, B) ) Is changed to a smaller value by a predetermined increase / decrease value (a, b, c, d, e) (S108). This is done until the power supply voltage becomes larger than the changed Z [V]. For example, when the measured power supply voltage is 19.5 V, the initial threshold value Z [V] is 18 V, and the increase / decrease value c is 1 V, the power supply voltage (19.5 V) is larger than 18 V (S102). Is reset to 19V, which is 1V higher (S104). Since the power supply voltage (19.5V) is not less than the modified Z (19V) (S106), Z is reset to 20V, which is 1V higher (S104). Then, since the power supply voltage (19.5V) becomes less than the changed Z (20V), the resetting of the threshold value in FIG. 7 is completed. During this period, other threshold values and reference values (X, Y, A, B) are also reset to larger values according to the corresponding increase / decrease values (a, b, d, e).

The above-mentioned resetting of the threshold value based on the power supply voltage is performed before the electric motor 20 is driven to start the machining work (after S22 in FIG. 5) and before the electric motor 20 is driven to start the machining work. It is supposed to be performed in the middle (after S70 in FIG. 6).

In particular, when the battery 14 is used as the power source, the power supply voltage decreases as the remaining battery level decreases, and the voltage supplied to the electromagnet 12 also decreases. Then, the magnetic flux density generated around the electromagnet 12 becomes small. That is, the magnitude of the magnetic flux density generated around the electromagnet 12 depends not only on the plate thickness of the workpiece but also on the magnitude of the power supply voltage. In the above embodiment, since the magnitude of each threshold value and the reference value is changed according to the magnitude of the power supply voltage to reset the normal operating range, the change in the magnetic flux density due to the change in the power supply voltage is judged to be lifted. By reducing the effect, it is possible to detect the floating of the electromagnet 12 more stably.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, it may be a machine tool to which other processing tools such as a drill can be attached instead of the annular cutter. Further, although the battery is used as the main power source in the above embodiment, an external power source such as an AC power source may be used as the main power source. Further, although the electric motor is used as the drive unit, another device such as an air motor may be used as the drive unit. In the above embodiment, the plate thickness is determined in three stages of α [mm] or more, less than α [mm] β [mm] or more, and less than β [mm] to set the normal operating range. The plate thickness may be determined steplessly to set the normal operating range. The magnitude of the magnetic flux density generated around the electromagnet also changes depending on the material of the work piece to which the electromagnet is magnetically attracted. Therefore, when the portable machine tool is used for workpieces of different materials, it is not always necessary to judge the plate thickness, and it is based on the output value of the magnetic sensor before the machining work. The normal operating range may be set directly.

1 Portable machine tool 10 Machine body 12 Electromagnet 14 Battery 16 Ring cutter 18 Machining tool mounting part 20 Electric motor 22 Gear mechanism 24 Lever 26 1st coil 30 2nd coil 34 Motor drive switch 36 Motor stop switch 38 Electromagnet switch 40 Lighting Switch 41 LED display 42 Magnetic sensor 46 Control circuit board 48 Control unit 50 Control power supply circuit 52 Motor control unit 54 Motor current detection unit 56 Coil control circuit 58 Coil disconnection detection circuit 60 Power supply voltage detection circuit

Claims

Machine tool body and
An electromagnet attached to the machine tool body and fixing the machine tool body to the work piece,
A magnetic sensor arranged around the electromagnet and
A control unit designed to control the operation of the electromagnet,
A drive unit for driving a machining tool attached to the machine tool body so as to perform machining work on the workpiece.
With
The magnetic sensor after the control unit sets the normal operating range based on the output value of the magnetic sensor while the electromagnet is operating and before the machining work by the drive unit is started, and after the machining work is started. A portable machine tool in which it is determined that the electromagnet has floated from the workpiece when the output value of is out of the normal operating range.
The magnetic sensor is adapted to detect the magnetic flux density in the magnetic circuit of the electromagnet formed through the workpiece, and the output value is a value indicating the magnitude of the magnetic flux density, claim 1. Described portable machine.
The normal operating range is a range in which the floating determination reference value determined based on the magnitude of the output value is set as the lower limit value.
The control unit is made to determine that the electromagnet has floated from the workpiece when the output value of the magnetic sensor after starting the machining work becomes less than the lift determination reference value. Or the portable machine tool according to 2.
The control unit is designed to detect the supply voltage to the electromagnet.
The claim is made so that the control unit sets the normal operating range based on the output value of the magnetic sensor and the supply voltage before the processing work by the driving unit is started while the electromagnet is operating. The portable machine tool according to any one of items 1 to 3.
The portable machine tool according to claim 4, wherein the control unit resets the normal operating range based on the magnitude of the supply voltage when the supply voltage changes during the machining operation. ..
When the output value of the magnetic sensor is equal to or higher than a predetermined first threshold value while the electromagnet is operating and before the processing work by the driving unit is started, the control unit raises the normal operating range by a predetermined first floating. Set the judgment reference value to the lower limit and set it to the lower limit.
When the output value is less than the first threshold value and greater than or equal to a predetermined second threshold value smaller than the first threshold value, the control unit sets the normal operating range smaller than the first floating determination reference value. The portable machine tool according to any one of claims 1 to 5, which is set in a range in which a predetermined second lift determination reference value is set as a lower limit value.
The claim that the driving of the driving unit cannot be started when the output value of the magnetic sensor is less than the second threshold value while the electromagnet is operating and before the processing work by the driving unit is started. The portable machine tool according to 6.
It also has a display unit that displays the status of the portable machine tool.
When the output value of the magnetic sensor is equal to or higher than the first threshold value and when the output value of the magnetic sensor is less than the first threshold value and greater than or equal to the second threshold value while the electromagnet is operating and before the processing work by the driving unit is started. The portable machine tool according to any one of claims 1 to 7, wherein the display is different depending on whether the value is less than the second threshold value.