JP2015030063A - Electric tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric tool which can reliably performs fastening work of a stopper.SOLUTION: An electric tool, which can fasten a stopper, comprises a motor which is capable of normal rotation or reverse rotation, a hammer rotated by the motor, an anvil which is intermittently struck by a first striking force with the hammer, current detection means which detects a first reverse curent value flown to the motor at each time of reverse rotation of the motor, and control means which controls rotation of the motor. When the first reverse current value is equal to or lower than a predetermined value, the control means discriminates whether or not also a second reverse current value, which is detected with the current detection means by next reverse rotation of the motor, is substantially same as the predetermined value.

Description

  The present invention relates to an electric tool, and more particularly to an electronic pulse driver that outputs a rotational driving force.

  A conventional electronic pulse driver as an electronic tool has a motor, a hammer driven by the motor, and an anvil on which the tip tool is detachable and is hit by the hammer. The motor can rotate in both directions, the motor rotates forward and the hammer strikes the anvil, the motor rotates backward and the hammer moves away from the anvil, and the motor rotates forward again and the hammer strikes the anvil. To do. By repeating this operation, the fastener can be fastened to the processing member with the tip tool.

JP 2011-031314 A

  In such an electronic pulse driver, when the current during forward rotation exceeds a predetermined value, it is determined that the stopper is seated on the workpiece, and the motor is stopped. However, the current may momentarily exceed a predetermined value due to galling between the stopper and the end tool, and there is a problem that the operation is stopped during the tightening operation. As a means for accurately determining the tightening torque, it is conceivable to newly provide a torque sensor. However, since the manufacturing cost increases, another control method has been desired.

  Then, an object of this invention is to provide the electric tool which can perform the fastening operation | work of a fastener reliably, without using a torque sensor.

  In order to achieve the above object, an electric tool according to the present invention is an electric tool capable of tightening a fastener, a motor capable of normal rotation or reverse rotation, a hammer rotated by the motor, and intermittent by the hammer. An anvil that is struck with a first striking force, current detecting means for detecting a first reverse current value that flows through the motor each time the motor reverses, and control means for controlling the rotation of the motor. The control means includes a second reverse current value detected by the current detection means by the next reverse rotation of the motor when the first reverse current value becomes equal to or less than a predetermined value. It is determined whether or not they are the same.

  With the above configuration, it is possible to confirm whether or not the fastening work for the processing member of the fastener has been performed reliably. In addition, by determining whether or not the reverse current values due to two consecutive strikes are below a predetermined value, an erroneous determination of the completion of the tightening operation due to a sudden increase in load during the tightening operation Can be avoided. Therefore, the fastener can be securely tightened.

  Preferably, the control means determines whether or not the second reverse current value is equal to or less than the predetermined value. When the second reverse current value is also equal to or lower than the predetermined value, that is, since the reverse current value is continuously equal to or lower than the predetermined value, it can be determined that the tightening operation has been completed. Therefore, the fastener can be securely tightened.

  Preferably, the predetermined value is a first threshold value corresponding to completion of fastening of the fastener by the first striking force, and the control means is configured such that the second reverse current value is the first threshold value. When it is determined that the following will occur, the driving of the motor is stopped.

  According to the above configuration, by confirming that the reverse rotation current value due to two consecutive hits becomes the same value, it can be detected that the fastening work of the fastener has been performed reliably, and the reliable fastening work It can be performed.

  Preferably, the predetermined value is a first threshold value corresponding to completion of fastening of the fastener by the first striking force, and the control means is configured such that the second reverse current value is the first threshold value. If it is determined that the value exceeds the value, the hammer hits the anvil with the hammer.

  According to the above configuration, it is possible to know that the fastening of the fastener is incomplete when the reverse rotation current value becomes the first threshold value, and the fastening operation by the second striking force is continued and reliably stopped. The tool can be fastened to the workpiece.

  Preferably, when the control means determines that the second reverse current value is lower than the first threshold value, the control means replaces the first striking force with a second smaller than the first striking force. Continue to hit the anvil with a striking force. According to the above configuration, after the end of the tightening work by the first striking force is estimated, the striking is continued with the second striking force smaller than the first striking force. Excess can be prevented.

  Preferably, the control means determines whether a third reverse current value resulting from the second striking force is equal to or less than a second threshold value corresponding to completion of fastening of the fastener by the second striking force. Determine whether or not. According to the said structure, it can be discriminate | determined whether the fastening operation | work with respect to the processed member of a fastener was performed reliably.

  Preferably, the control means stops driving the motor when the third reverse current value is equal to or less than the second threshold value. According to the said structure, it can be confirmed whether the fastening operation | work with respect to the process member of a fastener was performed reliably, and the interruption in the middle of a fastening operation | work can be prevented.

  Preferably, when the third reverse current value is larger than the second threshold value, the control means replaces the second striking force with a third striking force larger than the second striking force. Then continue to hit the anvil. According to the above configuration, the batting operation is continued with a large batting force, so that the batting operation can be completed in a short time.

  Preferably, the anvil is hit with a hitting force larger than the first hitting force. With the above configuration, the tightening operation can be completed in a short time.

  Preferably, the reverse current value is a peak value.

  Furthermore, the electric tool of the present invention is an electric tool capable of tightening a stopper, and is a motor that can be rotated forward or backward, a hammer that is rotated by the motor, and an anvil that is intermittently hit by the hammer. And a current detection means for detecting a reverse current value that flows through the motor when the motor rotates in reverse, and a control means for controlling the rotation of the motor, wherein the control means has the reverse current value not more than a predetermined value. When the reverse electric current value at the time of the next reverse rotation of the motor becomes equal to or less than the predetermined value, the motor is stopped.

  According to the above configuration, since the reverse rotation current value due to two consecutive hits continuously becomes a predetermined value or less, it can be confirmed that the fastening work of the fastener has been performed reliably. It is possible to avoid erroneous determination of the completion of the tightening operation due to the steep increase in load.

  Preferably, the control means controls the motor so that the hammer strikes the anvil with a first striking force, and the control means, after the reverse current value becomes equal to or less than the predetermined value, The motor is controlled so that the hammer striking force is a second striking force smaller than the first striking force. When the reverse rotation current value becomes a predetermined value or less, by continuing the hitting with the second hitting force smaller than the first hitting force, it is possible to reliably complete the fastening operation of the fastener, and excessively Tightening can be prevented.

  Preferably, after the reverse rotation current value becomes equal to or less than the predetermined value, the control means, when the reverse electric current value at the time of the next reverse rotation of the motor exceeds the predetermined value, the hammer impact force Controls the motor so that the third impact force is greater than the second impact force. If the reverse current value exceeds a predetermined value, it means that the tightening operation is in progress, so the striking force is increased to speed up the progress of the tightening operation. Therefore, the time required for the tightening operation can be shortened.

  Furthermore, the electric tool of the present invention is an electric tool capable of tightening a stopper, and is a motor that can be rotated forward or backward, a hammer that is rotated by the motor, and an anvil that is intermittently hit by the hammer. And a current detecting means for detecting a first reverse current value flowing through the motor when the motor rotates in reverse, and a control means for controlling the rotation of the motor, wherein the control means comprises the first reverse rotation. The motor is stopped when the fluctuation between the current value and the second reverse current value detected by the current detection means due to the next reverse rotation of the motor is equal to or less than a predetermined value.

  With the above configuration, it can be confirmed that the fastening operation of the fastener has been completed, and an erroneous determination of the completion of the fastening operation due to a sudden increase in load during the fastening operation can be avoided.

  Preferably, the apparatus has a trigger for operating start and stop of the motor, and the control unit performs the control when the operation amount of the trigger is maximum. If the amount of operation of the trigger is small, the amount of current supplied to the motor is also small, so it is difficult to think that the tightening operation is completed. Therefore, when the operation amount of the trigger is the maximum, the completion of the tightening work is determined by comparing the reverse current value, thereby improving the work efficiency.

  Preferably, the motor has a stop section between forward rotation and reverse rotation, and the reverse current value is detected in the stop section. In the stop period, since there is no fluctuation in the voltage value to the motor due to the load fluctuation, an accurate voltage value can be detected. As a result, an accurate reverse current value can be detected, and the completion of the fastening operation of the fastener can be determined more accurately.

  According to the electric tool of the present invention, even when the reverse rotation current value becomes a predetermined value or less due to a temporary and sudden load increase during the tightening operation, the tightening failure of the fastener is prevented. A reliable tightening operation can be performed.

It is sectional drawing of the electronic pulse driver which concerns on embodiment of this invention. It is a block diagram of the electronic pulse driver concerning an embodiment of the invention. It is a graph showing the electric current of the electronic pulse driver which concerns on embodiment of this invention, tightening torque, and load. It is a graph showing the electric current of the electronic pulse driver which concerns on embodiment of this invention, tightening torque, and load. It is a flowchart showing control in the pulse mode of the electronic pulse driver which concerns on embodiment of this invention. It is a flowchart which shows the striking operation / tightening torque determination process in FIG. It is a graph showing the relationship between the battery voltage of the electronic pulse driver which concerns on embodiment of this invention, an electric current threshold value, and impact power. It is a graph showing the electric current of the electronic pulse driver which concerns on other embodiment of this invention, tightening torque, and load. It is a flowchart which shows the other example of a striking operation / tightening torque determination process.

  Hereinafter, the configuration of the electronic pulse driver 1 according to the embodiment of the electric power tool of the present invention will be described with reference to FIGS. 1 to 4.

  As shown in FIG. 1, an electronic pulse driver 1, which is an example of an electric tool, mainly includes a housing 2, a motor 3, a hammer part 4, an anvil part 5, and a control part 6. The housing 2 is made of resin and forms an outer shell of the electronic pulse driver 1, and is mainly composed of a substantially cylindrical body portion 21 and a handle portion 22 extending from the body portion 21.

  In the body portion 21, the motor 3 is arranged so that the longitudinal direction thereof coincides with the axial direction of the motor 3, and the hammer portion 4 and the anvil portion 5 are arranged side by side toward one end side in the axial direction of the motor 3. Has been. In the following description, the anvil portion 5 side is defined as the front side, the motor 3 side is defined as the rear side, and a direction parallel to the axial direction of the motor 3 is defined as the front-rear direction. Further, the body part 21 side is defined as the upper side, the handle part 22 side is defined as the lower side, and the direction in which the handle part 22 extends from the body part 21 is defined as the vertical direction. Further, a direction orthogonal to the front-rear direction and the up-down direction is defined as the left-right direction.

  A metal hammer case 23 in which the hammer part 4 and the anvil part 5 are incorporated is arranged at a front side position in the body part 21. The hammer case 23 has a substantially funnel shape in which the diameter gradually decreases toward the front. In the hammer case 23, an opening 23a is formed at a front end portion, and a metal 23A is provided on an inner wall that defines the opening 23a. The metal 23A supports the anvil portion 5 so as to be rotatable.

  A light 2 </ b> A for irradiating a tip tool (not shown) mounted on a tip tool mounting portion 51, which will be described later, is disposed near the opening 23 a and below the hammer case 23. A dial 2B for switching the control mode and setting a tightening torque is disposed below the light 2A so as to be rotatable. The light 2 </ b> A and the dial 2 </ b> B are disposed at substantially the center position of the body portion 21 in the left-right direction. The body portion 21 is formed with an inlet and an exhaust port (not shown) through which outside air is sucked and discharged into the body portion 21 by a fan 32 described later. Further, a display unit 26 that displays which control mode is selected is disposed on the upper side and the rear side of the body unit 21. Further, the display unit 26 is provided with an LED 28. The LED 28 blinks when the tightening operation is completed without reaching the preset tightening torque, and warns the operator that the fastener is not fastened with the tightening torque.

  The handle portion 22 extends downward from a substantially central position in the front-rear direction of the body portion 21 and is configured integrally with the body portion 21. Inside the handle portion 22, the switch mechanism 7 is built, and a battery 24 for supplying power to the motor 3 and the like is detachably mounted at the lower end position thereof. A trigger 25 is provided above the handle portion 22 and at the front side position. A forward / reverse switching lever 27 for switching the rotation direction of the motor 3 is provided in the vicinity of the trigger 25 (FIG. 2).

  As shown in FIG. 1, the motor 3 is a brushless motor mainly composed of a rotor 3 </ b> A having an output shaft 31 and a stator 3 </ b> B disposed to face the rotor 3 </ b> A, and the axial direction of the output shaft 31 is the front-rear direction. Is arranged in the body part 21 so as to coincide with the above. The output shaft 31 protrudes forward and backward of the rotor 3A, and is rotatably supported on the body portion 21 by a bearing at the protruding portion. A fan 32 that rotates coaxially with the output shaft 31 is provided at a location protruding to the front side of the output shaft 31, and a pinion gear 31A rotates coaxially with the output shaft 31 at the foremost position of the location. It is provided to do. An inverter board 8 extending in a direction orthogonal to the output shaft 31 is provided behind the motor 3.

  The hammer part 4 is mainly composed of a gear mechanism 41 and a hammer 42, and is built in the front side of the motor 3 in the hammer case 23. The gear mechanism 41 is a two-stage planetary gear mechanism, and includes outer gears 41A and 41B, three planetary gears 41C and 41D, and a carrier 41E. The outer gears 41 </ b> A and 41 </ b> B are fixed in the hammer case 23.

  The first stage planetary gear mechanism will be described. The three planetary gears 41C are arranged around the pinion gear 31A as a sun gear so as to mesh with the pinion gear 31A, and are arranged inside the outer gear 41A so as to mesh with the outer gear 41A. The three planetary gears 41C are fixed to a carrier 41E having a sun gear. With such a configuration, as the pinion gear 31A rotates, the three planetary gears 41B revolve around the pinion gear 31A, and the rotation reduced by the revolution is transmitted to the sun gear of the carrier 41E. Similarly, in the second stage planetary gear mechanism, the rotation of the motor 3 is decelerated and transmitted to the hammer 42.

  The hammer 42 is disposed on the front side of the gear mechanism 41, and has a first engagement protrusion 42A and a second engagement protrusion 42B that are disposed opposite to the rotation shaft and project toward the front side.

  The anvil portion 5 is disposed in front of the hammer portion 4 and mainly includes a tip tool mounting portion 51 and an anvil 52. The tip tool mounting portion 51 is formed in a cylindrical shape and is rotatably supported in the opening 23a of the hammer case 23 via a metal 23A. The tip tool mounting portion 51 is provided with a perforation 51a into which a tip tool (not shown) is inserted in the front-rear direction, and a chuck 51A for holding the tip tool (not shown) is provided at the front end portion.

  The anvil 52 is configured to be integrated with the tip tool mounting portion 51 in the hammer case 23 at the rear of the tip tool mounting portion 51, and disposed opposite to the rotation center of the tip tool mounting portion 51. It has the 1st to-be-engaged protrusion 52A and the 2nd to-be-engaged protrusion 52B which protruded toward. When the hammer 42 rotates, the first engaging protrusion 42A and the first engaged protrusion 52A collide with each other, and at the same time, the second engaging protrusion 42B and the second engaged protrusion 52B collide with each other. Is transmitted to the anvil 52.

  Next, the configuration of the drive control system of the motor 3 will be described with reference to FIG. In the present embodiment, the motor 3 is a three-phase brushless DC motor, and the rotor 3A has a permanent magnet 3C including a plurality of sets (two sets in the present embodiment) N poles and S poles, and a stator 3B. Are star-connected three-phase stator windings U, V, and W.

  As shown in FIG. 2, the inverter substrate 8 is provided with six switching elements Q1 to Q6 such as FETs connected in a three-phase bridge form and three rotational position detecting elements 9. The rotational position detecting element 9 is provided at a position facing the permanent magnet 3C of the rotor 3A, and is arranged at predetermined intervals (for example, every angle of 60 °) in the circumferential direction of the rotor 3A.

  The control unit 6 is mounted as a control unit on a substrate disposed near the battery 24 in the handle unit 22, and is connected to the battery 24 and is connected to the display unit 26, the trigger 25 (switch mechanism 7), and the corrector. The reverse switching lever 27 is connected. Further, the control unit 6 includes a current detection circuit 61A, a voltage detection circuit 61B, a switch operation detection circuit 62, an applied voltage setting circuit 63, a rotation direction setting circuit 64, a rotor position detection circuit 65, and a rotation speed. A detection circuit 66, a calculation unit 68, and a control signal output circuit 69 are provided.

  The gates of the switching elements Q1 to Q6 of the inverter substrate 8 are connected to the control signal output circuit 69 of the control unit 6, and the drains or sources of the switching elements Q1 to Q6 are the stator windings U, V, Connected to W. The six switching elements Q1 to Q6 perform a switching operation according to the switching element drive signal input from the control signal output circuit 69, and the DC voltage of the battery 24 applied to the inverter board 8 is three-phase (U-phase, V-phase). And W phase) Electric power is supplied to the stator windings U, V, W as voltages Vu, Vv, Vw. Specifically, the stator windings U, V, and W that are energized by the output switching signals H1, H2, and H3 input from the control signal output circuit 69 to the positive power supply side switching elements Q1, Q2, and Q3, that is, the rotor The direction of rotation of 3A is controlled. Further, power is supplied to the stator windings U, V, and W by pulse width modulation signals (PWM signals) H4, H5, and H6 that are input from the control signal output circuit 69 to the negative power supply side switching elements Q4, Q5, and Q6. The amount, that is, the rotational speed of the rotor 3A is controlled.

  The current detection circuit 61 </ b> A detects a current supplied to the motor 3 as a current detection unit and outputs it to the calculation unit 68. The voltage detection circuit 61 </ b> B detects the voltage of the battery 24 and outputs it to the calculation unit 68. The switch operation detection circuit 62 detects the presence or absence of the operation of the trigger 25 and outputs it to the calculation unit 68. The applied voltage setting circuit 63 outputs a signal corresponding to the operation amount of the trigger 25 to the calculation unit 68.

  When detecting the switching of the forward / reverse switching lever 27, the rotation direction setting circuit 64 transmits a signal for switching the rotation direction of the motor 3 to the calculation unit 68.

  The rotor position detection circuit 65 detects the rotational position of the rotor 3 </ b> A based on the signal from the rotational position detection element 9 and outputs it to the computing unit 68. The rotation speed detection circuit 66 detects the rotation speed of the rotor 3 </ b> A based on the signal from the rotation position detection element 9 and outputs it to the calculation unit 68.

  The computing unit 68 includes a central processing unit (CPU) (not shown) for outputting a drive signal based on the processing program and data, and a storage unit 68A for storing the processing program and control data. The storage unit 68A stores a graph showing the relationship between the voltage of the battery 24 and the current threshold as shown in FIG. 4, a hitting start current threshold described later, and the like. The calculation unit 68 outputs the output switching signals H1, H2, and H3 based on the signals from the rotation direction setting circuit 64 and the rotor position detection circuit 65, and the pulse width modulation signal (PWM signal) based on the signal from the applied voltage setting circuit 63. ) H4, H5, and H6 are generated and output to the control signal output circuit 69. The PWM signal may be output to the positive power supply side switching elements Q1 to Q3, and the output switching signal may be output to the negative power supply side switching elements Q4 to Q6.

  Next, the control mode in the electronic pulse driver 1 will be described with reference to FIGS. The electronic pulse driver according to the present embodiment has three control modes of a drill mode, a clutch mode, and a pulse mode, and the mode can be switched by operating the dial 2B.

  The drill mode is a mode in which the hammer 42 and the anvil 52 are integrally rotated, and is mainly used when a wood screw is fastened to a processed member. The clutch mode is a mode in which the driving of the motor 3 is stopped when the current flowing through the motor 3 increases to a target value while the hammer 42 and the anvil 52 are integrally rotated. Used when fastening fasteners that appear on the exterior.

  In the pulse mode, as shown in FIG. 3, when the current flowing in the motor 3 increases to a predetermined value while the hammer 42 and the anvil 52 are integrally rotated, the forward rotation and the reverse rotation of the motor 3 are alternately performed. In this mode, the fastener is fastened by switching and hitting. The pulse mode is mainly used for fastening a long screw used in a place where it does not appear in the appearance. Thereby, a strong fastening force can be supplied, and at the same time, a repulsive force from the workpiece can be reduced.

  Next, the operation by the control unit 6 when the electronic pulse driver 1 performs the fastening operation in the pulse mode will be described with reference to FIGS.

  FIG. 3 is a graph showing the transition of current, tightening torque, and load acting on the electronic pulse driver 11 when fastening the fastener in the pulse mode. When the control mode is set to the pulse mode, when the trigger 25 is operated, the control unit 6 rotates the motor 3 to rotate the hammer 42 and the anvil 52 integrally. When the current exceeds a preset impact start current threshold at time t1, reverse rotation of the motor 3 is started at time t3 with a pause period from time t2 to time t3. Thereby, the hammer 42 and the anvil 52 are separated from each other in the rotation direction. The hitting start current threshold is a current value at which the hammer 42 starts hitting the anvil 52. The rest period refers to a period in which no current is applied to the motor 3. In the rest period from time t2 to time t3, the hammer 42 presses the anvil 52 in the rotational direction by inertial force.

After a pause period from time t4 to time t5, at time t5, the controller 6 causes the motor 3 to rotate forward. Thus, at time _{t D,} and the hammer 42 and the anvil 52 collide with each other. After a quiescent period from time t6 to time t7 has elapsed, at time t7, the controller 6 reversely rotates the motor 3 again. By repeating such control, the hammer 42 and the anvil 52 continuously collide, and a tightening torque is applied to the stopper. As the fastening of the fastener proceeds, the tightening torque increases and the repulsive force (load) after the hammer 42 strikes the anvil 52 increases. This is because when the fastening of the fastener proceeds, the rotational energy when the hammer 42 strikes the anvil 52 acts on the hammer 42 as a repulsive force without being used for the rotation of the anvil 52. Since the repulsive force acts in a direction to separate the hammer 42 from the anvil 52, the torque required to reverse the hammer 42 can be reduced. That is, since the reverse current flowing through the motor 3 can be reduced, the reverse current of the motor 3 gradually decreases as the tightening operation proceeds.

  At this time, the control unit 6 determines whether or not the reverse current value of the motor 3 detected for each impact is equal to or less than a predetermined current threshold value. When the reverse current value becomes equal to or less than the current threshold (20 [A] in the present embodiment) at time t10, the control unit 6 has reached the tightening torque of the target torque T (20 [Nm] in the present embodiment). Judge. Based on this determination, the control unit 6 performs the next hit as the determination hit, and compares the reverse current value flowing through the motor 3 at time t14 as a result of the determination hit with the current threshold value. If the reverse current value is equal to or less than the current threshold value, the control unit 6 determines that the fastening work of the fastener to the workpiece is completed and stops the motor 3. Judgment hitting is a second hitting force (target torque) that is weaker than the first hitting force (the hitting force before the hitting decision, 35 Nm) when the tightening operation is estimated from the reverse rotation current value. 20 Nm), and it is a hit for judging whether or not the fastening work of the fastener is reliably performed and completed. The tightening torque is a torque that acts on the stopper by the anvil 52 in an actual striking operation, that is, a striking force. The target torque is torque that acts on the electronic pulse driver 1 when the tightening operation is completed.

  On the other hand, as shown in FIG. 4, even if it is estimated that the reverse rotation current value at the time t20 is equal to or less than the current threshold value and the tightening operation is completed, the motor 3 is detected at the time t21 by the next determination hit. When the flowing reverse current value exceeds the current threshold value, the control unit 6 determines that the fastening operation of the fastener is still in progress and continues the hitting. Therefore, it is possible to prevent the fastening operation from being interrupted due to an unexpected increase in load, and to securely perform the fastening operation of the fastener.

  Next, the control flow of the electronic pulse driver 1 will be described with reference to FIGS.

  When the battery 24 is attached to the electronic pulse driver 1, the control unit 6 is activated and the flowchart starts. The control unit 6 determines whether or not the trigger 25 has been operated (S1). When the trigger 25 is not operated (S1: NO), S1 is looped. When the trigger 25 is operated (S1: YES), the control unit 6 rotates the motor 3 forward (S2). The controller 6 determines whether or not the current of the motor 3 has exceeded the impact start current threshold (S3). Specifically, the calculation unit 68 determines whether or not the current of the motor 3 exceeds the impact start current threshold value based on a signal from the current detection circuit 61A. When the current of the motor 3 is less than the impact start current threshold (S3: NO), the motor 3 is continuously rotated forward (S2). When the current of the motor 3 is equal to or greater than the impact start current threshold (S3: YES, t1 in FIG. 3), the process proceeds to the impact operation / tightening torque determination process (S4).

  As shown in FIG. 6, in the striking operation / tightening torque determination process, first, it is determined whether or not a hit with the first striking force to be performed is a determination hit (S11). Since the first impact performed in the fastening operation is not a determination impact (S11: NO), the process proceeds to S12. First, for example, the motor 3 is stopped during a pause period from time t4 to t5 (S12), and then the motor 3 is rotated forward from time t5 to t6 to perform impact (S13). During the rest period (S14) of the motor 3 from time t6 to time t7, the voltage value of the battery 24 is detected by the voltage detection circuit 61B, and a first current threshold value corresponding to the target torque is calculated (S15). Based on the signal from the voltage detection circuit 61B, the calculation unit 68 of the control unit 6 determines the first current threshold by referring to the graph shown in FIG. 7 stored in the storage unit 68A (S15). The first current threshold is a value set based on the battery voltage of the battery 24 and the set tightening torque. In the present embodiment, in order to perform the tightening operation in a short time, the first impact force is set to 35 Nm with respect to the target tightening torque of 20 Nm. FIG. 7 shows respective current threshold values when the tightening torque is 35 Nm and 20 Nm. The reason why the voltage value of the battery 24 is detected during the suspension period of the motor 3 is that an accurate voltage value can be detected because the voltage value does not fluctuate due to load fluctuations.

  The controller 6 reversely rotates the motor 3 from time t7 to time t8 (S16), and determines whether or not the operation amount of the trigger 25 is the maximum (S17). Specifically, the calculation unit 68 of the control unit 6 determines whether the operation amount of the trigger 25 is the maximum based on the signal from the applied voltage setting circuit 63. The electronic pulse driver 1 controls the current supplied to the motor 3 according to the operation amount of the trigger 25. That is, if the operation amount of the trigger 25 is small, the current supplied to the motor 3 is also small. Therefore, in order to fasten the fastener with the target torque T, the operation amount of the trigger 25 needs to be maximum.

  When the operation amount of the trigger 25 is maximum (S17: YES), the control unit 6 detects the reverse current of the motor 3 (S18), and the reverse current detected between time t7 and time t8 is S15. It is determined whether it is smaller than the calculated first current threshold value (S19). The reverse current is determined by the peak value. Specifically, the computing unit 68 compares the reverse current of the motor 3 with the first current threshold value based on a signal from the current detection circuit 61A. Usually, the first and second strikes have just started the tightening operation, and the amount of displacement of the stopper with respect to the processed member is large, so the amount of reverse current for reverse rotation of the motor 3 thereafter is large, It does not fall below the first current threshold (S19: NO).

  When it is determined that the operation amount of the trigger 25 is not the maximum (S17: NO), or when the reverse current of the motor 3 exceeds the first current threshold (S19: NO), the control unit 6 is engaged with the target torque T. It is presumed that it has not been made, and it is judged as judgment NG (S30). Then, the control unit 6 ends the striking operation / tightening torque determination process. If the reverse current of the motor 3 is equal to or less than the first current threshold value (S19: YES), the process proceeds to S20, and a determination blow described in detail later is started.

  The control unit 6 determines that the determination is NG (S30), and after finishing the striking operation / tightening torque determination process, returns to the control flow of FIG. 5 and determines whether the determination is OK or NG (S5). ). That is, the control unit 6 determines whether or not the fastener is fastened with the target torque T. In this case, the determination is NG (S5: NO), and it is next determined whether or not the trigger 25 is operated (S6). When the trigger 25 is continuously operated (S6: YES), the striking operation / tightening torque determination process (S4) is performed again. When the trigger 25 is not operated (S6: NO), the motor 3 is stopped (S7). At this time, since the determination is NG, the fastener is not fastened with the predetermined torque T. Therefore, the control unit 6 blinks the LED 28 to notify the operator that the fastener is not fastened with the predetermined torque T (S8).

  In the second batting operation / tightening torque determination process (S4) after time t8, since the next batting is not the batting (S11: NO), the control unit 6 determines that the reverse current value is equal to or less than the first threshold value. Until it becomes, the loop process consisting of S12 to S18, S19: NO, S30, S5: NO, S6: YES is repeatedly executed. Generally, as tightening proceeds, the load acting on the electronic pulse driver 1 increases, and the reverse current value of the motor 3 decreases as the load increases.

  After repeating the loop process, if the control unit 6 determines that the reverse current value detected at time t10 is equal to or less than the first threshold value (S19: YES), the fastener is fastened at the target torque T. It estimates and progresses to S20, and a judgment hit is started.

  In the determination hit, the motor 3 is stopped during a stop period from time t11 to t12 (S21), and then the motor 3 is rotated forward from time t12 to t13 for hitting (S22). The hitting at this time is performed with the second hitting force weaker than the first hitting force. During the rest period (S23) of the motor 3 from time t13 to time t14, the voltage value of the battery 24 is detected by the voltage detection circuit 61B, and the second current threshold value is calculated (S24). Based on the signal from the voltage detection circuit 61B, the calculation unit 68 of the control unit 6 refers to the graph shown in FIG. 7 stored in the storage unit 68A, so that the second current corresponding to the second impact force is obtained. A threshold value is determined (S24).

  The controller 6 reversely rotates the motor 3 from time t14 to time t15 (S25), and determines whether or not the operation amount of the trigger 25 is maximum (S26) as in S17.

  When the operation amount of the trigger 25 is maximum (S26: YES), the control unit 6 detects the reverse current of the motor 3 (S27), and the reverse current detected between time t14 and time t15 is S24. It is determined whether or not it is smaller than the calculated second current threshold value (S28). Specifically, the calculation unit 68 compares the reverse current of the motor 3 with the second current threshold value based on a signal from the current detection circuit 61A.

  As shown in FIG. 3, when the reverse current value detected between time t14 and time t15 of the motor 3 is equal to or smaller than the second threshold value (S28: YES), the control unit 6 determines that the stopper has a predetermined torque. It is determined that it is fastened at T, and it is determined that the determination is OK (S29). Then, the striking operation / tightening torque determination process is terminated. After the completion of the striking operation / tightening torque determination process, the control unit 6 returns to FIG. 5 and stops the motor 3 regardless of the operation of the trigger 25 (S9) because the determination is OK (S5: YES).

  On the other hand, as shown in FIG. 4, even when the reverse current value at time t20 is equal to or lower than the first threshold value, the reverse current value of the motor 3 detected at the subsequent time t21 is the second threshold value. Is exceeded (S28: NO), the control unit 6 determines that the fastener is not fastened with the target torque T, and determines that the determination is NG (S30). In this case, since the control unit 6 returns to the control flow of FIG. 5 and the determination is NG (S5: NO), when the trigger 25 is continuously operated (S6: YES), the batting operation / tightening is performed again. Torque determination processing (S4) is performed.

  When the striking operation / tightening torque determination process (S4) is performed again, since the determination striking has already started after time t20 (S11: YES), the control unit 6 proceeds to S20, and the above S20 to S27, S28. : NO, S30, and S4 to S6 in FIG. 5 are executed until the detected reverse current value becomes equal to or smaller than the second threshold value. Thereafter, for example, when the reverse current value at time t22 in FIG. 4 is equal to or smaller than the second threshold value, the control unit 6 determines that the determination is OK because S28 is YES (S29), and the striking operation / tightening is performed. The torque determination process is terminated. Then, the control unit 6 returns to the control flow of FIG. 5, and the determination is OK in S5 (S5: YES), so the motor 3 is stopped regardless of the operation of the trigger 25 (S9).

  Therefore, even if the tightening work is estimated to have been performed at the target torque due to momentary load fluctuations from the workpiece and the tightening work is interrupted in the middle, the fastener tightening work It is possible to avoid the interruption of the tightening work and complete the fastening work of the fastener by performing the determination hit after estimating that the work has been completed.

  According to the above configuration, when the control unit 6 first determines that the fastening work of the fastener to the workpiece has been completed, the reverse current value that flows through the motor 3 and the reverse current value of the motor 3 due to the next impact are determined. Are determined to be substantially the same (that is, when any of the reverse current values is equal to or less than the threshold value), it can be determined that the tightening operation has been performed reliably. Therefore, it is possible to reliably perform the tightening work by avoiding a stop in the middle of the tightening work due to a sudden load increase.

  According to the said structure, when the control part 6 becomes below the 1st threshold value corresponding to the completion of the fastening operation | work to the process member of a fastener by the reverse current resulting from the 1st striking force of the hammer 42 Since it is confirmed that the reversal current value that flows to the motor 3 by the next impact is equal to or less than the second threshold value, erroneous determination of the completion of the tightening operation due to an instantaneous load increase is prevented. Thus, a reliable tightening operation can be performed.

  According to the above configuration, since the hammer 42 is continuously struck with a striking force smaller than the initial striking force in the determination striking, it is possible to prevent over tightening of the fastener on the processed member.

  According to the above configuration, since the tightening operation is performed using a tightening torque larger than the target torque, the tightening operation can be completed in a short time.

  In the above embodiment, after the start of the determination hit shown in FIG. 6 (S20), the hammer 42 has a smaller hitting force than the initial hitting force. Without being hit by the hammer 42. In this case, the same value as the first threshold value can be used as the second threshold value, and the reliable completion of the tightening operation can be easily confirmed.

  In the above embodiment, after the start of the determination hitting, the hitting force is reduced and hitting with the hammer 42 is performed. However, if the hitting force is reduced, it takes time to complete the tightening operation. You can also For example, as shown in FIG. 8, after the reverse current value has decreased below the first threshold value at time t <b> 30, as shown in the control flow of FIG. 9, the judgment hit (20 Nm hit) starts at time t <b> 31 ( S20) When the reverse current value detected at time t32 is larger than the second threshold value due to the impact performed immediately after the start of the determination impact (S28: NO), the control unit 6 determines that the determination is NG ( S30). At this time, the control unit 6 performs the striking operation / tightening torque determination process 4 again through S5 and S6: YES in FIG. 5. When executing this process, the control unit 6 converts the striking force to the original strength at time t33. It is possible to return to the impact force (first impact force, 35 Nm impact) and perform the impact (FIG. 8, S11a). As a result, the time required for the tightening operation can be shortened. The reverse current value is compared with the current threshold value in steps S19 and S28. If the difference between the reverse current values detected in steps S18 and S27 is equal to or less than a predetermined value (that is, substantially the same), the determination is OK in step S29. It can also be.

  Further, instead of the battery 24, a commercial power source can be used as a power source.

DESCRIPTION OF SYMBOLS 1 Electronic pulse driver 3 Motor 4 Hammer part 5 Anvil part 6 Control part 42 Hammer 52 Anvil 61A Current detection circuit 61B Voltage detection circuit 62 Switch operation detection circuit 63 Applied voltage setting circuit 66 Rotation speed detection circuit

Claims (16)

An electric tool capable of tightening a stopper,
A forward or reverse motor,
A hammer rotated by the motor;
An anvil that is intermittently hit by the hammer with a first hitting force;
Current detecting means for detecting a first reverse current value flowing through the motor each time the motor rotates in reverse;
Control means for controlling the rotation of the motor,
The control means is configured such that when the first reverse current value becomes equal to or less than a predetermined value, the second reverse current value detected by the current detection means by the next reverse rotation of the motor is substantially the same as the predetermined value. A power tool characterized by determining whether or not.   The power tool according to claim 1, wherein the control means determines whether or not the second reverse current value is equal to or less than the predetermined value. The predetermined value is a first threshold value corresponding to completion of tightening of the stopper by the first striking force,
3. The electric tool according to claim 1, wherein the control unit stops driving the motor when it is determined that the second reverse current value is equal to or less than the first threshold value. The predetermined value is a first threshold value corresponding to completion of tightening of the stopper by the first striking force,
3. The electric tool according to claim 1, wherein when the control unit determines that the second reverse current value exceeds the first threshold value, the hammer continues to hit the anvil with the hammer. 4. .   When the control means determines that the second reverse current value is lower than the first threshold value, the control means uses a second striking force smaller than the first striking force instead of the first striking force. The power tool according to claim 4, wherein the anvil is continuously hit.   The control means determines whether or not a third reverse current value caused by the second impact force is equal to or less than a second threshold corresponding to completion of fastening of the fastener by the second impact force. The power tool according to claim 5, wherein the power tool is discriminated.   The electric power tool according to claim 6, wherein the control means stops the driving of the motor when the third reverse current value is equal to or less than the second threshold value.   When the third reverse current value is larger than the second threshold value, the control means replaces the second striking force with the third striking force larger than the second striking force and the anvil. The power tool according to claim 6, wherein the hammering is continued.   The power tool according to any one of claims 1 to 8, wherein the anvil is hit with a hitting force larger than the first hitting force.   The electric power tool according to any one of claims 1 to 8, wherein the reverse current value is a peak value. An electric tool capable of tightening a stopper,
A forward or reverse motor,
A hammer rotated by the motor;
An anvil that is intermittently hit by the hammer;
Current detection means for detecting a reverse current value flowing through the motor when the motor rotates in reverse;
Control means for controlling the rotation of the motor,
The control means stops the motor when the reverse current value at the next reverse rotation of the motor becomes equal to or less than the predetermined value after the reverse rotation current value becomes equal to or less than the predetermined value. tool. The control means controls the motor so that the hammer strikes the anvil with a first striking force;
The control means controls the motor so that a hammering force of the hammer becomes a second striking force smaller than the first striking force after the reverse rotation current value becomes equal to or less than the predetermined value. The power tool according to claim 11.   When the reverse current value at the time of the next reverse rotation of the motor exceeds the predetermined value after the reverse rotation current value becomes equal to or less than the predetermined value, the control means determines the hammering force of the hammer to the first value. The power tool according to claim 12, wherein the motor is controlled to have a third striking force larger than a second striking force. An electric tool capable of tightening a stopper,
A forward or reverse motor,
A hammer rotated by the motor;
An anvil that is intermittently hit by the hammer;
Current detecting means for detecting a first reverse current value flowing through the motor when the motor rotates in reverse;
Control means for controlling the rotation of the motor,
The control means controls the motor when a variation between the first reverse current value and a second reverse current value detected by the current detection means due to the next reverse rotation of the motor is equal to or less than a predetermined value. An electric tool characterized by stopping. A trigger for operating start and stop of the motor;
The said control part performs the said control when the operation amount of the said trigger is the maximum, The electric tool as described in any one of Claim 1-14 characterized by the above-mentioned. The motor has a stop section between forward rotation and reverse rotation,
The electric power tool according to any one of claims 1 to 15, wherein the reverse current value is detected in the stop section.

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