JP7304267B2 - Portable machine tool - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable machine tool, and more particularly to a portable machine tool in which machining is performed while a machine tool body is fixed to a workpiece by electromagnets.

2. Description of the Related Art Among machine tools such as drilling machines, there are portable machine tools that can be carried to a work site to perform machining work on a workpiece. Such a portable machine tool can be fixed to the work piece by various methods, but in consideration of ease of handling and convenience, the machine tool is fixed to the work piece by magnetic attraction using an electromagnet. there is something (Patent Document 1)

In such a portable machine tool, a microcomputer is usually used to control the driving of the electric motor and the operation of the electromagnet. When power is supplied to the microcomputer by connecting the portable machine tool or turning on the power switch, the microcomputer automatically starts control.

JP 2014-231129 A

Portable machine tools are used in various places, and sometimes in places where there is a lot of electromagnetic noise or where the voltage of an external power source is unstable. Then, noise from the outside may cause the microcomputer to malfunction and be reset. In addition, the microcomputer may malfunction and be reset due to noise from a control circuit including the microcomputer, an electric motor, or the like. In a portable machine tool equipped with an electromagnet, the microcomputer controls the electromagnet to stop immediately after the start-up, as it may be dangerous if the electromagnet suddenly activates when power supply is started. On the other hand, if the microcomputer is reset for some reason while the portable machine tool is fixed with an electromagnet, the microcomputer will abruptly stop the operation of the electromagnet, causing the portable machine tool to topple over. There is a risk of falling.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a portable machine tool capable of preventing the electromagnet from being stopped unexpectedly when the microcomputer is reset while the electromagnet is operating. .

That is, the present invention
machine tool body;
an electromagnet attached to the machine tool body for fixing the machine tool body to a workpiece;
a microcomputer that controls the electromagnet;
a non-volatile memory that stores operating state data indicating the operating state of the electromagnet;
with
The microcomputer rewrites the operating state data to a value indicating operating when the electromagnet is started to operate, and rewrites the operating state data to a value indicating stopped when the electromagnet stops operating. and
When the control by the microcomputer is started, the microcomputer reads out the operation state data stored in the nonvolatile memory, and if the operation state data is a value indicating that the operation is in progress, the To provide a portable machine tool in which an electromagnet is in an activated state, and the electromagnet is in a stopped state when the operating state data is a value indicating that the electromagnet is stopped.

In the portable machine tool, the operating state of the electromagnet is written as operating state data in the nonvolatile memory, and the microcomputer reads out the operating state data stored in the nonvolatile memory when control is started. The operation of the electromagnet is controlled according to the value indicated by the operating state data. Therefore, when the microcomputer is temporarily stopped due to noise or the like and the control is resumed immediately after being reset, the operating state of the electromagnet before resetting can be maintained. Therefore, when the microcomputer is reset while the electromagnet is operating, it is possible to prevent the electromagnet from being stopped unexpectedly.

again,
further comprising a voltage monitoring unit that monitors the voltage supplied to the portable machine tool,
The microcomputer stops the operation state data while continuing the operation of the electromagnet when the voltage detected by the voltage monitoring unit drops below a predetermined reference voltage value while the electromagnet is operating. It can be rewritten to a value indicating medium.

If the voltage drops below a predetermined reference voltage value, there is a risk that the power supply will stop. As described above, when the voltage drops below the reference voltage value while the electromagnet is operating, by rewriting the operating state data to a value indicating that it is stopped, the power supply is restarted and the microcomputer It is possible to prevent the electromagnet from suddenly starting to operate when the control by is started.

Further, after the voltage detected by the voltage monitoring unit drops below a predetermined reference voltage value while the electromagnet is operating, the voltage monitoring unit detects When the applied voltage rises to a predetermined reference voltage value or higher, the microcomputer can rewrite the operating state data to a value indicating that the device is operating.

If the voltage drops below the reference voltage and then rises above the reference voltage while microcomputer control continues, it can be said that the power supply was stopped for an extremely short time. Then, the operating state data can be matched with the operating state of the electromagnet by returning the operating state data to a value indicating that the electromagnet is in operation. By doing so, it is possible to prevent the operation of the electromagnet from stopping when the microcomputer is reset later.

Further comprising a power storage member connected to the microcomputer,
When power supply to the portable machine tool is stopped, power stored in the power storage member can be supplied to the microcomputer to continue control of the microcomputer.

An embodiment of a portable machine tool according to the present invention will be described below with reference to the accompanying drawings.

1 is a side view of a portable machine tool according to an embodiment of the present invention; FIG. FIG. 2 is a sectional view of the portable machine tool of FIG. 1; FIG. 2 is a functional block diagram of the portable machine tool of FIG. 1; 4 is a first flow chart showing the operation of the portable machine tool of the present invention; 4 is a second flow chart showing the operation of the portable machine tool of the present invention;

A portable machine tool 1 according to one 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, as shown in FIG. A battery 14 that serves as a power source for the portable machine tool 1 is detachably attached to the rear of the machine tool body 10 . As shown in FIG. 2, the machine tool main body 10 includes a working tool mounting portion 18 to which an annular cutter 16 is detachably mounted. 20 are provided. The machining tool mounting portion 18 and the electric motor 20 are drivingly connected via a gear mechanism 22 comprising a plurality of gears. As shown in FIG. 1 , a lever 24 is attached to the machine tool 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 first coil 26 and a ring-shaped second coil 30 as well. When power is supplied from the battery 14 to the first coil 26 and the second coil 30 while the portable machine tool 1 is placed on a magnetic material, the machine tool main body is moved by the magnetic attraction force generated by the electromagnet 12. 10 is fixed with respect to the workpiece, which is a magnetic material. The portable machine tool 1 presses an annular cutter 16 rotationally driven by an electric motor 20 against the workpiece while the machine tool main body 10 is fixed to the workpiece by the electromagnet 12 . It is a drilling machine designed to perform processing operations on objects.

As shown in FIG. 1, a motor drive switch 34 for starting driving the electric motor 20, a motor stop switch 36 for stopping driving the electric motor 20, and an electromagnet 12 are provided on the side of the machine tool body 10. An electromagnet switch 38 is provided for starting and stopping the operation of the. 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 lower front surface of the machine tool body 10 . These switches 34, 36, 38, and 40 are all momentary switches that are ON only while being pressed and return OFF when released. The machine tool main body 10 is further provided with an LED display section 41 for indicating the state of the portable machine tool 1 to the operator.

As shown in FIG. 2, a magnetic sensor 42 is attached to the electromagnet 12 . The magnetic sensor 42 is adapted to measure the magnitude of 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 microcomputer 48 (FIG. 3) for controlling the electric motor 20, the electromagnet 12, and the like. ing. When the battery 14 is attached to the machine tool main body 10, power is supplied from the battery 14 to the microcomputer 48 via the control power supply circuit 50, and the microcomputer 48 is activated. The microcomputer 48 controls driving of the electric motor 20 according to the operating states of the motor drive switch 34 and the motor stop switch 36 . Specifically, when the motor drive switch 34 is pressed to turn on, the electric motor 20 starts to be driven, and when the motor stop switch 36 is pressed to turn on, the electric motor 20 stops driving. The microcomputer 48 controls the rotational speed of the electric motor 20 by sending a control signal to the motor control section 52 . Further, the microcomputer 48 monitors the load condition of the electric motor 20 by detecting the amount of current flowing through the electric motor 20 with the motor current detector 54 . The microcomputer 48 starts operating the electromagnet 12 when the electromagnet switch 38 is pressed to turn it on while the electromagnet 12 is not operating, and turns it on when the electromagnet switch 38 is pressed while the electromagnet 12 is operating. When the state is reached, the operation of the electromagnet 12 is stopped. Microcomputer 48 controls power supplied to first coil 26 and second coil 30 via coil control circuit 56 . Since the first coil 26 and the second coil 30 are connected in series, the power supplied to the first coil 26 and the second coil 30 will generally be the same. The coil disconnection detection circuit 58 detects currents flowing through the first coil 26 and the second coil 30 to detect disconnection of the first coil 26 and the second coil 30 . When disconnection of the first coil 26 or the second coil 30 is detected, the microcomputer 48 stops control and turns on the LED display section 41 to inform the user that the coils 26, 30 are disconnected. Further, the microcomputer 48 memorizes that the coils 26 and 30 are disconnected, and lights up the LED display section 41 when the battery 14 is once disconnected and reconnected and the control of the microcomputer 48 is resumed. It also informs the user that the coils 26, 30 are disconnected.

The control circuit board 46 further includes a microcomputer capacitor (storage member) 60 connected to the microcomputer 48 and an electromagnet capacitor 62 connected to the electromagnet 12 . These microcomputer capacitor 60 and electromagnet capacitor 62 are charged with electric power supplied from the battery 14 when the battery 14 is connected. When the power supply from the battery 14 stops, the power stored in the microcomputer capacitor 60 continues the control of the microcomputer 48, and the power stored in the electromagnet capacitor 62 continues the operation of the electromagnet 12. It has become so. The control circuit board 46 further includes a voltage monitoring section 64 for monitoring the voltage supplied from the battery 14 connected to the machine tool body 10 .

Control circuit board 46 further includes non-volatile memory 66 . The nonvolatile memory 66 stores control programs, control parameters for controlling the electromagnet 12 and the electric motor 20, and the like. The nonvolatile memory 66 also stores operating state data indicating the operating state of the electromagnet 12 . When the operation of the electromagnet 12 is started, the microcomputer 48 rewrites the operation state data to a value indicating that the electromagnet 12 is "in operation", and when the operation of the electromagnet 12 is stopped, the operation state data is changed to a value indicating that the electromagnet is "in operation". Rewrite to a value indicating "stopping". In addition, the microcomputer 48 reads the operating state data stored in the nonvolatile memory 66 when control is started, and operates the electromagnet 12 when the operating state data is a value indicating "in operation". state, and when the operating state data is a value indicating "stopped", the electromagnet 12 is set to a stopped state. In this embodiment, the nonvolatile memory 66 is an EEPROM arranged on the control circuit board 46, but it may be built in the microcomputer 48 or externally attached to the control circuit board 46. may Other forms of memory may also be used.

Based on the flow chart of FIG. 4, the operation of the portable machine tool 1 will be described in more detail. When the battery 14 is attached to the machine tool main body 10 and power supply is started (S10), control by the microcomputer 48 is started (S12). The microcomputer 48 first reads the operating state data stored in the nonvolatile memory 66 (S14). If the read operating state data is a value indicating "stopped" (S16), the electromagnet 12 is not operated and the electromagnet switch 38 is on standby (S18). When the electromagnet switch 38 is pushed and turned on (S18), the microcomputer 48 starts operating the electromagnet 12 (S20). Also, the microcomputer 48 rewrites the operating state data stored in the nonvolatile memory 66 to a value indicating "in operation" (S22). On the other hand, if the read operation state data is a value indicating "in operation" (S16), the microcomputer 48 starts operating the electromagnet 12 (S24). When the motor drive switch 34 is pushed and turned on while the electromagnet 12 is operating (S26), the microcomputer 48 starts driving the electric motor 20 (S28). Then, when the motor stop switch 36 is pushed and turned on (S30), the microcomputer 48 stops driving the electric motor 20 (S32). When the electromagnet switch 38 is pressed to turn it ON while the electric motor 20 is stopped (S34), the microcomputer 48 stops the operation of the electromagnet 12 (S36). The data is rewritten to a value indicating "stopped" (S38). Thereafter, the microcomputer 48 returns to the standby state until the electromagnet switch 38 is operated (S18).

The microcomputer 48 also performs the controls shown in the flow chart of FIG. 5 when the electromagnet 12 is activated. Specifically, when the operation of the electromagnet 12 is started in S22 or S24 (S50), the voltage supplied from the battery 14 is measured by the voltage monitoring unit 64 (S52). If the measured voltage is less than the predetermined reference voltage value, the microcomputer 48 continues the operation of the electromagnet 12 and rewrites the operating state data to a value indicating "stopped" (S56). Here, the reference voltage value is a voltage value so low that the electric motor 20, the electromagnet 12, and the microcomputer 48 cannot operate normally. It is conceivable that the supply voltage becomes less than the reference voltage value when, for example, the battery 14 is temporarily removed and the power supply is stopped. Since the portable machine tool 1 is provided with the microcomputer capacitor 60 as described above, even if the supply voltage drops below the reference voltage value due to, for example, the power supply being stopped, the microcomputer capacitor 60 will continue to operate. By supplying the stored power to the microcomputer 48, the microcomputer 48 can continue control for a while. When the measured voltage is equal to or higher than the reference voltage value (S54), the operation state data is confirmed (S58), and when the operation state data is "stopped" (S58), the operation state data is changed to "operating medium" (S60). When the electromagnet 12 is in operation, the above control (S50-S60) is repeated, and when the operation of the electromagnet 12 stops, the control ends.

At S58, the operating state data stored in the non-volatile memory 66 becomes a value indicating "stopped" when the operating state data is rewritten to "stopped" at S56. That is, after the measured voltage drops below the reference voltage value (S54) and the operating state data is rewritten to "stopped" (S56), the measured voltage rises above the reference voltage value (S54), and the This is the case where the status data has been confirmed (S58).

In the portable machine tool 1, the operating state of the electromagnet 12 is written as operating state data in the nonvolatile memory 66, and the microcomputer 48 reads the operating state data stored in the nonvolatile memory 66 when control is started. The data is read out, and the operation of the electromagnet 12 is controlled according to the value indicated by the read operation state data. Therefore, when the control is resumed immediately after the microcomputer 48 is temporarily stopped due to noise or the like and reset, the operating state of the electromagnet 12 before reset can be maintained. Therefore, for example, when the microcomputer 48 is reset while the electromagnet 12 is operating, it is possible to prevent the operation of the electromagnet 12 from being stopped unexpectedly. However, after the battery 14 is removed and the power supply is stopped and the control of the portable machine tool 1 is completely stopped, when the charged battery 14 is attached and the power supply is restarted, the electromagnet 12 will not operate. A sudden start can be dangerous. Therefore, in the portable machine tool 1, when the voltage measured by the voltage monitoring unit 64 is less than the predetermined reference voltage value, it is highly possible that the power supply has been stopped. to prevent the electromagnet 12 from suddenly starting to operate when the power supply is restarted. After the measured voltage drops below the reference voltage value, if the measured voltage rises above the reference voltage value while the control of the microcomputer 48 continues, the stoppage of the power supply will be extremely short. It is judged that it is time, and the operation state data is returned to "in operation" while the operation of the electromagnet 12 is continued. By doing so, it is possible to prevent the operation of the electromagnet 12 from suddenly stopping when the microcomputer 48 is reset while the operation of the electromagnet 12 is being continued.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, instead of the annular cutter, it may be a machine tool to which other working tools such as a drill can be attached. Further, although the battery is used as the power source in the above embodiment, an external power source such as an AC power source may be used. A primary battery or a secondary battery can be used instead of a capacitor as a power storage member for supplying power to the control unit and the electromagnet when the power supply is stopped.

1 Portable Machine Tool 10 Machine Tool Body 12 Electromagnet 14 Battery 16 Annular Cutter 18 Machining Tool Attachment 20 Electric Motor 22 Gear Mechanism 24 Lever 26 First Coil 30 Second Coil 34 Motor Drive Switch 36 Motor Stop Switch 38 Electromagnet Switch 40 Lighting Switch 41 LED display section 42 Magnetic sensor 46 Control circuit board 48 Microcomputer 50 Control power supply circuit 52 Motor control section 54 Motor current detection section 56 Coil control circuit 58 Coil disconnection detection circuit 60 Microcomputer capacitor (power storage member)
62 electromagnet capacitor 64 voltage monitoring unit 66 nonvolatile memory

Claims (4)

machine tool body;
an electromagnet attached to the machine tool body for fixing the machine tool body to a workpiece;
a microcomputer that controls the electromagnet;
a non-volatile memory that stores operating state data indicating the operating state of the electromagnet;
with
The microcomputer rewrites the operating state data to a value indicating operating when the electromagnet is started to operate, and rewrites the operating state data to a value indicating stopped when the electromagnet stops operating. and
When the control by the microcomputer is started, the microcomputer reads out the operation state data stored in the nonvolatile memory, and if the operation state data is a value indicating that the operation is in progress, the 1. A portable machine tool, wherein an electromagnet is in an activated state, and when the operating state data is a value indicating that the electromagnet is in a stopped state. further comprising a voltage monitoring unit that monitors the voltage supplied to the portable machine tool,
The microcomputer stops the operation state data while continuing the operation of the electromagnet when the voltage detected by the voltage monitoring unit drops below a predetermined reference voltage value while the electromagnet is operating. 2. The portable machine tool according to claim 1, which is rewritten to a value indicating medium. The voltage detected by the voltage monitoring unit while the microcomputer continues to control after the voltage detected by the voltage monitoring unit drops below a predetermined reference voltage value while the electromagnet is operating 3. The portable machine tool according to claim 2, wherein the microcomputer rewrites the operation state data to a value indicating that the operation is in operation when the voltage rises to a predetermined reference voltage value or higher. further comprising a power storage member connected to the microcomputer,
4. When power supply to said portable machine tool is stopped, power stored in said power storage member is supplied to said microcomputer to continue control of said microcomputer. The portable machine tool according to any one of 1.

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