Working machine and punching method

Abstract

The present invention provides an operating machine and a punching method capable of improving workability. The operating machine (1) includes a motor (6), a trigger switch (7) for indicating the drive of the motor (6), and a microcomputer (40) for controlling the drive of the motor (6). If the microcomputer (40) detects a sharp rise in the motor current, it stops the motor (6) without switching to the retry mode. When the microcomputer (40) detects an overload without a sharp rise in the motor current, it switches to the retry mode. In the retry mode, the motor (6) is repeatedly started and stopped. When the load applied to the front end tool (31) is removed during the execution of the retry mode, the microcomputer (40) returns to the normal mode while the trigger switch (7) remains on.

Description

Technical Field

[0001] The present invention relates to a working machine such as a vibration drill and a drilling method using the working machine. Background Art

[0002] Patent Document 1 below discloses a drilling tool equipped with a lock release mode for releasing the locked state if the tool end and the workpiece become locked during operation. Patent Document 2 below discloses a power tool that, when detecting that the tool end is about to be locked by a hard object such as a stone during operation, increases output to eliminate the cause.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: International Publication No. 2015 / 029660

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 9-277195 Summary of the Invention

[0007] Problems to be solved by the invention

[0008] In the piercing tool of Patent Document 1, if the piercing tool enters a locked state, the operator must release the lock and restart the work. During this operation, the operator must release the trigger and pull the trigger again at least once. Together with the trigger operation before entering the locked state, the operator must operate the trigger at least twice, resulting in poor workability.

[0009] In the power tool disclosed in Patent Document 2, if the tool tip is detected as being locked, the output is increased to eliminate the cause, resulting in a high torque acting on the hand. Furthermore, if locking is performed with the output increased, there is a greater risk of backlash than before. Furthermore, reactivating the motor after it has stopped due to locking requires re-operation of the trigger.

[0010] The present invention has been made in recognition of such a situation, and an object of the present invention is to provide a working machine and a drilling method capable of improving workability.

[0011] Means for solving problems

[0012] One embodiment of the present invention is a work machine. The work machine has:

[0013] motor;

[0014] a working unit configured to be driven by the motor and capable of performing a predetermined work;

[0015] a control unit configured to control the motor; and

[0016] an operating unit configured to instruct the control unit to drive the motor,

[0017] It is characterized by:

[0018] The control unit is configured as follows:

[0019] When the operating unit is operated, a normal mode of continuously driving the motor is executed.

[0020] When the normal mode is executed, if the torque applied to the motor satisfies a first condition, a retry mode is executed, wherein the retry mode alternately repeats a stop control for stopping the motor and a retry control for driving the motor with a torque smaller than the torque when the first condition is satisfied.

[0021] When the retry mode is executed, if the torque applied to the motor satisfies a second condition, the retry mode is terminated and the motor is continuously driven.

[0022] The control unit may be configured to determine that the first condition is satisfied when the torque applied to the motor increases in a predetermined manner and / or the rotation speed of the motor decreases in a predetermined manner.

[0023] The control unit may be configured to determine that the first condition is satisfied when the torque applied to the motor reaches a first threshold value.

[0024] The control unit may be configured to execute the retry control until the torque applied to the motor reaches a second threshold value in the retry mode, and execute the stop control when the torque applied to the motor reaches the second threshold value.

[0025] The second threshold value may be configured to be a value smaller than the first threshold value.

[0026] The control unit may be configured to determine that the second condition is satisfied when a predetermined time has passed in a state where the torque applied to the motor has not reached the second threshold value.

[0027] The control unit may continue the stop control when the retry control is repeated a predetermined number of times.

[0028] Another embodiment of the present invention is a punching method using a work machine. This method is a punching method using a work machine, and the work machine has:

[0029] a motor; a front end tool configured to be driven by the motor to open a hole in a component;

[0030] a control unit configured to control the motor; and

[0031] an operating unit configured to instruct the control unit to drive the motor,

[0032] It is characterized by:

[0033] The perforation method has the following features:

[0034] In a first step, an operator operates the operating unit, and the control unit continuously drives the motor to rotate the tip tool to drill a hole in a component.

[0035] In a second step, the front end tool stops in the hole due to overload;

[0036] In a third step, the control unit executes a retry mode that alternately repeats a stop control for stopping the motor and a retry control for driving the motor;

[0037] In a fourth step, the operator removes the load applied to the front end tool; and

[0038] In the fifth step, the control unit terminates the retry mode and continuously drives the motor to rotate the tip tool to drill a hole in the component again.

[0039] The retry control in the third step may drive the motor with a torque smaller than that of driving the motor in the first step.

[0040] The driving of the motor in the fifth step may be performed by driving the motor with a torque greater than that in the driving of the motor in the third step.

[0041] The stop control may be continued if the retry control in the third step is repeated a predetermined number of times.

[0042] If the increase in the load per unit time in the second step is abrupt, the driving of the motor may be stopped without transitioning to the third step.

[0043] The tip tool may continue to be stopped from the time it stops in the second step until it rotates in the fifth step.

[0044] Furthermore, any combination of the above-described constituent elements or any conversion of the description of the present invention between devices or systems may also be effective as additional modes of the present invention.

[0045] Effects of the Invention

[0046] According to the present invention, a working machine and a drilling method capable of improving workability can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a side view of the working machine 1 according to the embodiment of the present invention.

[0048] Figure 2 It is a top view of the working machine 1.

[0049] Figure 3 It is an upper front view of the working machine 1.

[0050] Figure 4 It is a side sectional view of the working machine 1 .

[0051] Figure 5 1 is a circuit block diagram of the working machine 1.

[0052] Figure 6 This is a control flow chart of the working machine 1.

[0053] Figure 7 This is a graph showing an example of changes in the current flowing through the motor 6 in the working machine 1 , the rotation speed of the motor 6 , and the duty ratio of the rotation control of the motor 6 .

[0054] Figure 8 This is a waveform diagram showing the actual measurement of the rotation speed of the motor 6 and the current flowing through the motor 6 during the no-load operation of the working machine 1 .

[0055] Figure 9 This is a waveform diagram showing the actual measurement of the rotation speed of the motor 6 and the current flowing through the motor 6 during normal drilling of the working machine 1 .

[0056] Figure 10 This is a measured waveform diagram of the rotation speed of the motor 6 and the current flowing through the motor 6 when the operation of the motor 6 is stopped due to failure to return to normal control after the working machine 1 shifts to the retry mode.

[0057] Figure 11 This is a waveform diagram of the actually measured rotation speed of the motor 6 and the current flowing through the motor 6 when the working machine 1 repeats the operation of the normal mode and the retry mode.

[0058] Figure 12 This is a waveform diagram of the actually measured rotation speed of the motor 6 and the current flowing through the motor 6 when the motor 6 is stopped due to overload during normal control in the working machine 1 . DETAILED DESCRIPTION

[0059] Hereinafter, the same or equivalent structural elements, components, etc. shown in the various drawings are marked with the same reference numerals, and repeated descriptions are omitted as appropriate. The embodiments do not limit the invention but are illustrative. All features and combinations thereof described in the embodiments are not necessarily limited to the essential contents of the invention.

[0060] This embodiment relates to a working machine 1. The working machine 1 is a vibration drill. Figures 1 to 4 The mechanical structure of the working machine 1 will be described. Figure 1 and Figure 3 The front-back, top-bottom, and left-right directions that are orthogonal to each other in the working machine 1 are defined. Figure 4 In order to show the meshing structure of the reduction gear mechanism, the Figure 3 A partial cross-sectional view of the cross section was obtained at AOBCD.

[0061] The working machine 1 includes a housing 3. The housing 3 includes a motor housing 3a, a handle 3b, a fan guide 3c, an intermediate cover 3d, and a gear cover 3e. The handle 3b extends from the rear of the motor housing 3a. The handle 3b has a D-shape when viewed from the side. The intermediate cover 3d is connected and fixed to the front of the motor housing 3a via the fan guide 3c. The gear cover 3e is connected and fixed to the front of the intermediate cover 3d.

[0062] The handle 3b is provided with a forward / reverse switch 5 and a trigger switch 7. The trigger switch 7 is an operating unit for the operator to switch the drive and stop of the motor 6. Figure 5 The microcomputer 40 instructs the operating unit of the motor 6 to drive. If the operator pulls the trigger switch 7 (performs the on operation), the motor 6 is driven, and if the operator releases the operation of the trigger switch 7 (performs the off operation), the motor 6 stops. The forward and reverse switching switch 5 is configured to switch the rotation direction of the motor 6 when the trigger switch 7 is operated. Figure 4 As shown, a control board 26 is housed in the lower portion of the handle 3b. Switch elements 27 and the like are provided on the control board 26. A battery pack 4 serving as a power source for the working machine 1 is detachably connected to the lower end of the handle 3b.

[0063] like Figure 4 As shown, the motor housing 3a houses the motor 6. The central axis of the rotating shaft 6a of the motor 6 is parallel to the front-to-back direction. The rear portion of the rotating shaft 6a is supported by a bearing 11. The front portion of the rotating shaft 6a of the motor 6 is supported by a bearing 12. Bearings 11 and 12 are, for example, ball bearings. A fan 10 is mounted behind the bearing 12, in front of the rotating shaft 6a. The fan 10 is surrounded by a fan guide 3c. The fan 10 rotates integrally with the motor 6, generating airflow to cool the motor 6 and other components.

[0064] A first pinion 14 is formed in the portion of the rotating shaft 6a forward of the bearing 12. The first pinion 14 meshes with a first gear 15. The first gear 15 is provided at the rear of the intermediate shaft 16 and rotates integrally with the intermediate shaft 16. The central axis of the intermediate shaft 16 is parallel to the front-to-back direction. The rear end of the intermediate shaft 16 is supported by a bearing 28. The front end of the intermediate shaft 16 is supported by a bearing 29. Bearings 28 and 29 are, for example, needle roller bearings.

[0065] In front of the first gear 15, a second pinion 17 is provided on the intermediate shaft 16. The second pinion 17 is meshed with the second gear 18. The second gear 18 is provided at the rear of the main shaft 19 and rotates integrally with the main shaft 19. The center axis of the main shaft 19 is parallel to the front-to-back direction. Since the second gear 18 is spline-engaged with the second pinion 17 in a manner that allows it to slide back and forth, the main shaft 19 can move back and forth relative to the housing 3. The first pinion 14 and the first gear 15, as well as the second pinion 17 and the second gear 18 constitute a reduction mechanism (rotation transmission mechanism). The reduction mechanism is housed inside the intermediate cover 3d and the gear cover 3e. The rotation of the motor 6 is reduced in two stages by the reduction mechanism and transmitted to the main shaft 19 and the front end tool 31.

[0066] The rear end of the main shaft 19 is supported by a bearing 30. The bearing 30 is, for example, a needle bearing. A steel ball (spherical body) 20 is provided at the rear end of the main shaft 19. Behind the steel ball 20, the switching shaft 13 is supported on the intermediate cover 3d in a rotatable manner. The switching shaft 13 is cylindrical with a center axis perpendicular to the front-to-back direction, and has a partially cut-out recess on the outer peripheral surface of the middle portion. When the recess of the switching shaft 13 is opposite to the steel ball 20, it is in vibration drilling mode, and when the outer peripheral surface of the switching shaft 13 other than the recess is opposite to the steel ball 20, it is in drilling mode. The mode switching lever 8 provided on the intermediate cover 3d is an operating part for mode switching, which is used to rotate the switching shaft 13 around its own center axis. The operator can switch between the vibration drilling mode and the drilling mode by operating the mode switching lever 8 in the left and right directions.

[0067] In front of the second gear 18, a first ratchet 21 is provided around the main shaft 19. The first ratchet 21 is fixed to the gear cover 3e and does not rotate with the main shaft 19. A spring 22 is provided around the main shaft 19 to apply force to the main shaft 19 forward with respect to the first ratchet 21. In front of the first ratchet 21, a second ratchet 23 is provided around the main shaft 19. The second ratchet 23 is fixed to the main shaft 19 and rotates with the main shaft 19. The front surface of the first ratchet 21 is opposite to the rear surface of the second ratchet 23. Pawls are provided on the front surface of the first ratchet 21 and the rear surface of the second ratchet 23, respectively. The main shaft 19 is supported by a bearing 24 in front of the second ratchet 23. The bearing 24 is, for example, a ball bearing. A chuck (drill chuck) 9 is mounted on the front end portion of the main shaft 19 that protrudes forward from the gear cover 3e. As Figure 1 As shown in FIG. 1 , a drill 31 serving as a working unit is detachably mounted on the chuck 9 .

[0068] In drill mode, the outer circumference (cylindrical outer circumference) of the switching shaft 13, excluding the recessed portion, contacts the steel ball 20. Consequently, the spindle 19 cannot move in the front-to-back direction relative to the housing 3, and the front surface of the first ratchet 21 and the rear surface of the second ratchet 23 remain separated. Consequently, the spindle 19 continues to rotate without vibration, allowing the drill bit mounted on the chuck 9 to drill a hole in the workpiece (member).

[0069] In vibration drilling mode, the recessed portion of the switching shaft 13 faces the steel ball 20. Consequently, the spindle 19 can be retracted relative to the housing 3 by the depth of the recessed portion. Consequently, when the drill bit mounted on the chuck 9 is pressed against the workpiece, the spindle 19 retreats relative to the housing 3, overcoming the bias of the spring 22. The front surface of the first ratchet 21 comes into contact with the rear surface of the second ratchet 23. Consequently, the engagement of the pawl on the front surface of the first ratchet 21 with the pawl on the rear surface of the second ratchet 23 imparts vibration to the spindle 19. The drill bit mounted on the chuck 9 is simultaneously vibrated as it rotates, effectively drilling the workpiece.

[0070] Figure 5 1 is a circuit block diagram of the working machine 1. Figure 5 The inverter circuit 53 and the control circuit unit 60 shown are provided in Figure 4 The control substrate 26 is provided. The inverter circuit 53 may be provided on a substrate different from the control circuit unit 60. The inverter circuit 53 includes six switching elements Q1 to Q6 such as FETs and IGBTs connected in a three-phase bridge configuration. Figure 4 The switching element 27 shown is connected to Figure 5 The switching elements Q1 to Q6 are turned on and off according to the control of the microcomputer 40 , for example, PWM control (duty cycle control), and convert the DC power supplied from the battery pack 4 into AC power for driving the motor 6 and supply the AC power to the motor 6 .

[0071] The control circuit unit 60 includes a microcomputer (microcontroller) 40 serving as a control unit, a step-down circuit 41, a control system power supply circuit 42, a communication circuit 43, a battery temperature detection circuit 44, an overdischarge detection circuit 45, a current detection circuit 46, a control signal output circuit 47, a rotor position detection circuit 48, a FET temperature detection circuit 49, a battery voltage detection circuit 50, and an LED control circuit 51. The step-down circuit 41 steps down the output voltage of the battery pack 4. The control system power supply circuit 42 converts the output voltage of the step-down circuit 41 into a power supply voltage for the microcomputer 40 and supplies it to the microcomputer 40. The communication circuit 43 is a circuit for communication between the microcomputer 40 and the battery pack 4. The battery temperature detection circuit 44 detects the temperature of the battery pack 4 based on a temperature detection signal from the battery pack 4 and transmits it to the microcomputer 40. The overdischarge detection circuit 45 detects overdischarge of the battery pack 4 based on an overdischarge detection signal from the battery pack 4 and transmits it to the microcomputer 40.

[0072] The current detection circuit 46 detects the motor current (hereinafter also referred to as "motor current") based on the voltage across a resistor R provided in the path of the motor 6 current and transmits the detected motor current to the microcomputer 40. The control signal output circuit 47 applies control signals to the control terminals (gates) of the switching elements Q1 to Q6 in accordance with the control of the microcomputer 40. The rotor position detection circuit 48 detects the rotational position of the motor 6 based on the output signals of three magnetic sensors 52 (e.g., Hall effect ICs) provided near the motor 6 and transmits the detected signals to the microcomputer 40. The FET temperature detection circuit 49 detects the temperature of the switching elements Q1 to Q6 based on the output signals of unillustrated temperature sensors (e.g., thermistors) provided near the switching elements Q1 to Q6 and transmits the detected signals to the microcomputer 40. The battery voltage detection circuit 50 detects the output voltage of the battery pack 4 and transmits the detected signals to the microcomputer 40. The LED control circuit 51 controls the lighting of the unillustrated LEDs in accordance with the control of the microcomputer 40.

[0073] The microcomputer 40 operates by controlling the output voltage of the system power supply circuit 42. According to the operation of the trigger switch 7, the microcomputer 40 controls the switching elements Q1 to Q6 via the control signal output circuit 47 to control the drive of the motor 6 (the current supply to the motor 6). When the microcomputer 40 stops the motor 6, it stops the current supply to the motor 6. At this time, the microcomputer 40 can also perform braking control. The microcomputer 40 has an overload protection function. Overload protection is a protection when the load (torque) of the motor 6 becomes too large, and includes short-circuit current protection (SD), overcurrent protection, and motor lock protection. The microcomputer 40 monitors the load of the motor 6 through the motor current.

[0074] Short-circuit current protection stops the motor 6 when the motor current meets the short-circuit condition. The short-circuit condition is that the motor current is detected to be above the short-circuit threshold value (e.g. 187A) within the short-circuit determination time (e.g. 10μS). Overcurrent protection stops the motor 6 when the motor current meets the first or second overcurrent condition. The first overcurrent condition is that the motor current is detected to be above the first overcurrent threshold value (e.g. 160A) within the first determination time (e.g. 1msec). The second overcurrent condition is that the motor current is detected to be above the second overcurrent threshold value (e.g. 60A) within the second determination time (e.g. 100msec). The second overcurrent threshold value corresponds to Figure 7 The second overcurrent threshold is an example of the first threshold of the present invention. The motor lock protection stops the motor 6 when the rotation speed of the motor 6 (hereinafter also referred to as "motor rotation speed") becomes less than the threshold.

[0075] The microcomputer 40 has an emergency stop function for the motor 6. The emergency stop function is a function that stops the motor 6 when a sharp rise in motor current (steep current slope) is detected. A sharp rise in motor current is when the motor current rises from a first emergency stop threshold (first RFC threshold) (e.g., 40A) to a second emergency stop threshold (second RFC threshold) (e.g., 60A) within a sharp rise determination time (e.g., 10 msec). Regardless of the strength of the pressure applied by the tip tool 31 against the workpiece, a sharp rise in motor current will occur when the tip tool 31 is accidentally locked in the hole of the workpiece. As an example, accidental locking occurs when the tip tool 31 accidentally hits a harder portion of a part of the workpiece during a drilling operation. On the other hand, when the tip tool 31 is locked in the hole of the workpiece due to excessive pressure applied by the tip tool 31 against the workpiece, the rise in motor current is relatively gradual. As described later, in this embodiment, different controls are implemented depending on whether the rise in motor current is sharp when the motor current exceeds the second overcurrent threshold.

[0076] In the working machine 1 , there are the following four states as control states (control modes) of the motor 6 by the microcomputer 40 .

[0077] 1. Stop State The stop state is a state in which the motor 6 is stopped, and the drive control of the motor 6 by the microcomputer 40 is not performed.

[0078] 2. Startup State (Startup Mode) ... The startup state is the state that occurs after the microcomputer 40 starts the motor 6 and before a first predetermined time, for example, 300 msec, has passed. In the startup state, the microcomputer 40 stops the motor 6 if it detects a sudden increase in motor current or an overload. If the motor 6 stops in the startup state, the retry control described below is not performed. The microcomputer 40 transitions to the next operating state after the first predetermined time has passed while the motor 6 is being driven since it was started.

[0079] 3. Operating state (normal mode)... In the operating state, the control performed by the microcomputer 40 is different when a sudden increase in motor current is detected and when an overload is detected. When the microcomputer 40 detects a sudden increase in motor current, it determines that an impact is applied to the main body (recoil occurs) due to the sudden locking of the motor 6, and stops the motor 6. In this way, the recoil can be suppressed, and the failure of the working machine 1 can be suppressed by suppressing heat. The operator eliminates the error caused by the sudden increase in motor current by turning off the trigger switch 7 (releasing the operation of the trigger switch 7) (if the trigger switch 7 is pressed, the motor 6 becomes capable of being driven). When an overload is detected without detecting a sudden increase in motor current, the microcomputer 40 stops the motor 6 and transitions to the next retry state. The case where an overload is detected without detecting a sudden increase in motor current in the operating state is an example of the torque of the motor 6 increasing in a predetermined manner, and is an example of satisfying the first condition of the present invention.

[0080] 4. Retry state (retry mode) ... In the retry state, the microcomputer 40 stops the motor 6 (performs stop control) as an overcurrent protection even if the third overcurrent condition is satisfied. The third overcurrent condition is that the motor current is detected to be higher than the third overcurrent threshold value (e.g., 30A) which is lower than that in the start state and the operation state within a third determination time (e.g., 1msec). The third overcurrent threshold value corresponds to Figure 7 The second clutch threshold value of the present invention. The third overcurrent threshold value is an example of the second threshold value of the present invention. The purpose of adding the third overcurrent condition is to reduce the backlash caused by the retry. In the retry state, when the microcomputer 40 detects a sharp rise in motor current or overload within a second predetermined time from the start of the motor 6, for example, within 500msec, the motor 6 stops and immediately restarts (retry). When the second predetermined time has passed since the start of the motor 6 while the motor 6 is kept driven, the microcomputer 40 changes to the above-mentioned operating state. The case where the second predetermined time has passed since the start of the motor 6 while the motor 6 is kept driven is an example of satisfying the second condition of the present invention. When the microcomputer 40 restarts (retry control) after repeating the stop control of the motor 6 a predetermined number of times (for example, 10 times), no further retry control is performed and the motor 6 is maintained in the stopped state.

[0081] Figure 6 This is a control flow chart for the working machine 1. When the trigger switch 7 is turned on (S2) in the stop state (S1) as the initial state, the microcomputer 40 starts the motor 6 (S3), and the motor 6 enters the start state (S4). Before 300 msec has passed since the start of the motor 6 ("No" in S5), if the microcomputer 40 detects a sudden increase in motor current or an overload ("Yes" in S6 or "Yes" in S7), the motor 6 stops (S8). Thereafter, even if the trigger switch 7 continues to be turned on, the microcomputer 40 does not start the motor 6 ("Yes" in S9). If the trigger switch 7 is turned off ("No" in S9), the microcomputer 40 returns to S1. If 300 msec has passed since the start of the motor 6 ("Yes" in S5) without detecting a sudden increase in motor current or an overload ("No" in S6 or "No" in S7), the microcomputer 40 transitions to the operating state of the motor 6 (S10).

[0082] In the operating state, the microcomputer 40 continues to drive the motor 6 as long as the trigger switch 7 is on (YES in S13) unless a sudden increase in current or an overload is detected (No in S11, No in S12). If the trigger switch 7 is off (No in S13), the microcomputer 40 stops the motor 6 (S14) and returns to S1. If the microcomputer 40 detects a sudden increase in motor current (YES in S11), the microcomputer 40 stops the motor 6 (S15). Thereafter, even if the trigger switch 7 remains on, the microcomputer 40 does not start the motor 6 (YES in S16). If the trigger switch 7 is off (No in S16), the microcomputer 40 returns to S1. If an overload is detected (YES in S12) without detecting a sudden increase in motor current (No in S11), the microcomputer 40 stops the motor 6 (S17) and transitions to the retry state (S20).

[0083] In the retry state, the microcomputer 40 adds a retry threshold for overload protection (S21). The addition of the retry threshold corresponds to the addition of the third overcurrent condition (30A×1msec) described above. When the trigger switch 7 is off ("YES" in S22), the microcomputer 40 stops the motor 6 and then returns to S1. When the trigger switch 7 is on ("NO" in S22), if the motor 6 stops ("YES" in S23), the microcomputer 40 starts the motor 6 (S24). If the motor 6 does not stop ("NO" in S23), the microcomputer 40 stops the motor 6 (S28) if a sudden increase in motor current or an overload is detected ("YES" in S26 or "YES" in S27) before 500msec has passed since the motor 6 was started ("NO" in S25). If the number of retries, i.e., the number of times the motor 6 has been started in S24, is less than 10 times (No in S29), the microcomputer 40 returns to S22. If the number of retries reaches 10 times (Yes in S29), the microcomputer 40 does not start the motor 6 even if the trigger switch 7 remains on (Yes in S30). If the trigger switch 7 remains off (No in S30), the microcomputer 40 returns to S1. If the microcomputer 40 does not detect a sudden increase in motor current or overload while the trigger switch 7 remains on (No in S22, No in S23, No in S26, No in S27), and if 500 msec has passed since the motor 6 was started (Yes in S25), the microcomputer 40 returns from the retry state to the operating state (S31). The retry threshold (30 A x 1 msec) added in S21 is cleared when the retry state ends.

[0084] Figure 7 : is a graph showing an example of changes in the motor current, the motor speed, and the duty ratio (hereinafter also simply referred to as "duty ratio") of the rotation control of the motor 6 in the working machine 1. Figure 7 There are two cases recorded together. The solid lines of the current curve and the speed curve correspond to the first case, and the single-point dashed line corresponds to the second case. In addition, the duty cycle is represented by the dotted line only in the first case. Figure 7 In the figure, during the period from time t2 to time t3, the time axis on the horizontal axis and the duty ratio on the vertical axis are magnified for easy viewing.

[0085] First, the first case is described. At time t0, the microcomputer 40 starts the motor 6. At this time, the front end tool 31 is not in contact with the material to be cut, but is in a no-load state. In the start-up control of the motor 6, the microcomputer 40 uses soft start control to slowly increase the duty cycle to the target value, so that the motor current and the motor speed slowly increase. At time t1, the front end tool 31 is pressed against the material to be cut, and the hole-cutting operation begins. Then, as the load increases, the motor current increases and the motor speed decreases. At time t2, when the front end tool 31 is locked (stopped) in the hole of the material to be cut due to the load and the motor current becomes 60A, the microcomputer 40 reduces the duty cycle to 0. As a result, the motor current becomes 0 and the motor 6 stops.

[0086] The microcomputer 40 executes the retry mode after time t2. Specifically, the microcomputer 40 repeatedly performs the following control: after stopping the motor 6, the motor 6 is restarted, and the motor 6 is stopped when the motor current reaches 30A. Soft start control is also performed when the motor 6 is started during the retry control. During the period from time t2 to t3, the tip tool 31 is locked, and even if the motor 6 is started, the tip tool 31 does not rotate. During this period, even if the motor 6 is started, the motor 6 only rotates slightly to an extent equivalent to the clearance of the gear meshing. The time from restarting the motor 6 to stopping when the tip tool 31 is locked is, for example, approximately 100 msec. In addition, in this case, the duty cycle just before the motor 6 stops is, for example, approximately 20%. At time t3, if the operator pulls the tip tool 31 out of the hole in the workpiece (removing the load applied to the tip tool 31), during the subsequent starting of the motor 6, even at time t4, 500 msec after starting, the motor current does not exceed 30A. Thus, the microcomputer 40 ends the retry mode and returns to the normal control of continuously driving the motor 6 ( Figure 6 The operator can perform the drilling operation on the workpiece again while turning on the trigger switch 7.

[0087] Next, the second scenario will be described. In the second scenario, shortly before time t2, the tip tool 31 suddenly locks from a no-load state. Consequently, the motor current rapidly increases from 40A to 60A within 10 msec. In this case, the microcomputer 40 reduces the duty cycle to 0, stopping the motor 6. When the microcomputer 40 stops the motor 6 due to a sudden increase in motor current, the retry mode described above is not performed.

[0088] Figure 8 This is a measured waveform diagram of the motor speed and motor current during no-load operation of the working machine 1. Figure 8 In the figure, the upper part indicates the motor speed and the lower part indicates the motor current. Figures 9 to 12 The same is true in . Figure 8The waveform is executed without making the front end tool 31 contact with the cut material. Figure 6 This corresponds to the situations of S1 to S14. Figure 9 The waveform diagram is a diagram showing the rotation speed of the motor 6 and the current flowing through the motor 6 during normal drilling of the working machine 1. The waveform diagram is a diagram showing the rotation speed of the motor 6 and the current flowing through the motor 6 during normal drilling of the working machine 1. Figure 6 This corresponds to the situations of S1 to S14.

[0089] Figure 10 The waveform diagram of the motor speed and motor current is shown in FIG. 1 , which is a waveform diagram of the motor speed and motor current measured when the motor 6 stops operating after the working machine 1 switches to the retry mode and cannot be restored to the normal control. Figure 6 This corresponds to the situations of S1 to S13, S11, S12, S17, and S20 to S30.

[0090] Figure 11 The waveform diagram is a measured waveform diagram of the rotation speed of the motor 6 and the current flowing in the motor 6 when the normal mode and the retry mode are repeatedly performed in the working machine 1. This waveform diagram is the same as the waveform diagram when the tip tool 31 is repeatedly performed in contact with the workpiece. Figure 6 It corresponds to the situations of S1~S13, S11, S12, S17, S20~S29, S22~S25, and S31.

[0091] Figure 12 The waveform diagram of the motor speed and motor current is shown in FIG. 1 , which is a waveform diagram of the motor speed and motor current measured when the motor 6 is stopped due to overload during normal control of the working machine 1. Figure 6 The corresponding S1~S13, S11, S15. In addition, Figures 9 to 12 The waveform is a result of using a core drill with a diameter of 120 mm as the front end tool 31.

[0092] According to this embodiment, the following effects can be obtained.

[0093] (1) The microcomputer 40 executes a retry mode for locking the tip tool 31 when the force pressing the tip tool 31 against the workpiece (hereinafter referred to as "pressing force") is too strong. If the pressing force of the tip tool 31 is reduced during the execution of the retry mode, the microcomputer 40 returns to the normal mode even if the trigger switch 7 remains on. Therefore, after locking the tip tool 31, the operator does not need to operate the trigger switch 7 again, thereby improving workability.

[0094] (2) In the retry mode, the microcomputer 40 repeatedly stops and restarts the motor. This notifies the operator that the pressing force is too strong, prompting the operator to reduce the pressing force. In other words, the retry mode allows the operator to be informed that the pressing force is too strong and provides an opportunity to reduce the pressing force, thereby improving workability.

[0095] (3) If the microcomputer 40 detects a sudden increase in the motor current, it stops the motor 6 without switching to the retry mode. On the other hand, if the microcomputer 40 detects an overload without a sudden increase in the motor current, it switches to the retry mode. This can suppress the backlash that would cause the housing 3 to swing if the tip tool 31 were accidentally locked. Furthermore, the execution of the retry mode can improve workability as described above in the event that the tip tool 31 is locked due to excessive pressing force.

[0096] (4) The microcomputer 40 adds a stop condition (30 A x 1 msec) based on a motor current lower than that in the normal mode in the retry mode. Therefore, the torque (burden) applied to the operator's hand in the retry mode is reduced, and workability is improved.

[0097] While the present invention has been described above using embodiments as examples, those skilled in the art will appreciate that various modifications may be made to the various structural elements and processing steps of the embodiments within the scope of the claimed patent protection.

[0098] The microcomputer 40 may also monitor the load (torque) of the motor 6 using the motor speed. In this case, if the motor speed decreases slowly when it drops below the threshold speed, the microcomputer 40 switches to the retry mode. If the speed decreases rapidly, the microcomputer 40 may stop the motor 6 without switching to the retry mode. The working machine 1 is not limited to a vibration drill and may also be another drilling tool such as an impact drill, or may be a working machine other than a drilling tool whose tip tool can be locked.

[0099] Description of Reference Numerals

[0100] 1…Working machine, 3…Casing, 3a…Motor housing, 3b…Handle, 3c…Fan guide, 3d…Intermediate cover, 3e…Gear cover, 4…Battery pack, 5…Forward / reverse switch, 6…Motor (electric motor), 6a…Rotating shaft (output shaft), 7…Trigger switch, 8…Mode switching lever, 9…Chuck, 10…Fan, 11, 12…Bearings, 13…Switching shaft, 14…First pinion, 15…First gear, 16…Intermediate shaft, 17…Second pinion, 18…Second gear, 19…Main shaft, 20…Steel ball (sphere), 21…First ratchet, 22…Spring, 23…Second ratchet, 2 4…Bearing, 26…Control board, 27…Switching element, 28, 29…Bearing, 30…Bearing, 31…Front-end tool (drill bit), 40…Microcomputer (control unit), 41…Step-down circuit, 42…Control system power supply circuit, 43…Communication circuit, 44…Battery temperature detection circuit, 45…Overdischarge detection circuit, 46…Current detection circuit, 47…Control signal output circuit, 48…Rotor position detection circuit, 49…FET temperature detection circuit, 50…Battery voltage detection circuit, 51…LED control circuit, 52…Magnetic sensor (Hall IC), 53…Inverter circuit, 60…Control circuit unit.

Claims

1. A working machine comprising: motor; a working unit configured to be driven by the motor and capable of performing a predetermined work; a control unit configured to control the motor; and an operating unit configured to instruct the control unit to drive the motor, It is characterized in that The control unit is configured as follows: When the operating unit is operated, a normal mode of continuously driving the motor is executed. When the normal mode is executed, if a first condition is satisfied, a retry mode is executed, wherein the retry mode alternately repeats a stop control for stopping the motor and a retry control for driving the motor with a torque smaller than the first condition. When the retry mode is executed, if a second condition is satisfied, the retry mode is terminated and the motor is continuously driven.

2. The working machine according to claim 1, characterized in that The control unit is configured to determine that the first condition is satisfied when the torque applied to the motor increases in a predetermined manner and / or the rotation speed of the motor decreases in a predetermined manner.

3. The working machine according to claim 1, wherein: The control unit is configured to determine that the first condition is satisfied when the torque applied to the motor reaches a first threshold value.

4. The working machine according to claim 3, characterized in that: The control unit is configured to execute the retry control until the torque applied to the motor reaches a second threshold value in the retry mode, and to execute the stop control when the torque applied to the motor reaches the second threshold value.

5. The working machine according to claim 4, characterized in that: The second threshold is configured to be a value smaller than the first threshold.

6. The working machine according to claim 4, characterized in that The control unit is configured to determine that the second condition is satisfied when a predetermined time has passed in a state where the torque applied to the motor does not reach the second threshold.

7. The working machine according to claim 1, characterized in that The control unit continues the stop control when the retry control is repeated a predetermined number of times.

8. A control method using a working machine, the working machine having: motor; a front end tool configured to be driven by the motor and capable of performing a predetermined operation; a control unit configured to control the motor; and an operating unit configured to instruct the control unit to drive the motor, It is characterized in that The control method has the following features: In a first step, an operator operates the operating unit, and the control unit executes a normal mode of continuously driving the motor to rotate the tool tip to perform a predetermined operation. In a second step, when the control unit executes the normal mode, a first condition is satisfied and the tip tool stops due to a load; In a third step, the control unit executes a retry mode that alternately repeats a stop control for stopping the motor and a retry control for driving the motor at a torque smaller than the first condition; In a fourth step, the operator removes the load applied to the front end tool; and In the fifth step, the control unit terminates the retry mode and continuously drives the motor to rotate the tool tip to perform a predetermined operation.

9. The control method according to claim 8, characterized in that: The driving of the motor in the fifth step drives the motor with a torque greater than that in the driving of the motor in the third step.

10. The control method according to claim 8, characterized in that: If the retry control in the third step is repeated a predetermined number of times, the stop control is continued.

11. The control method according to claim 8, characterized in that: If the increase in the load per unit time in the second step is a sudden increase, the driving of the motor is stopped without transitioning to the third step.

12. The control method according to claim 8, characterized in that: The tip tool remains in a stopped state from the time it stops in the second step until it rotates in the fifth step.

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