JP2010149251A - Impact type screwing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an impact type screwing device that is made compact and light-weight by efficiently arranging circuit boards in a limited space. <P>SOLUTION: In the impact type screwing device including a motor 3, a rotation control circuit 7a controlling rotation of the motor 3, an impact unit 4 driven by the motor, an output shaft 5 mounted with a tip tool, and a housing to accommodate them, the housing includes a body part 6a accommodating the motor and the impact unit, a grip part 6b extending in generally vertical direction from the body part 6a to be grasped by a worker, and a circuit board accommodating part 6c arranged at the tip of the grip part 6b, and a plurality of the circuit boards are arranged in the circuit board accommodating part side by side in the vertical direction with respect to a split plane. Holding parts 21a-21c holding the circuit boards are formed on each side of the housing split. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an impact-type screw tightening device that is driven to rotate by a motor and tightens a fastening member such as a screw by using an intermittent striking force generated by a striking means.

  As an impact-type screw tightening device for tightening screws, bolts, etc., a device using an oil pulse unit that generates an impact force using hydraulic pressure is known. A tool using an oil pulse unit has a feature that operation noise is low because there is no collision between metals. As an example of such a device, there is, for example, Patent Document 1, an air motor or a DC motor is used as power for driving the oil pulse unit, and the output shaft of the motor is directly connected to the oil pulse unit. Pulling the trigger switch to activate the device drives the motor. Then, an external control box (external connection device) detects whether the tightening has been performed with a predetermined tightening torque, and stops the rotation of the motor when the predetermined tightening value is reached.

Japanese Patent Laid-Open No. 2007-30056

  In recent years, a brushless DC motor has been used as a drive source of a portable impact type screw fastening device. A brushless DC motor has the advantages of being able to control rotation with high accuracy, maintenance-free, long life, low loss, and increased workload. A brushless DC motor is a DC motor without a brush (rectifying brush), which uses a winding on the stator side and a permanent magnet on the rotor side, and sequentially energizes a predetermined coil with power driven by an inverter. To rotate the rotor. In an electric tool using a brushless DC motor, for example, a switching element for turning on and off energization of a stator winding and a control circuit for generating a control signal for turning on and off the switching element are provided in the housing. Must be mounted on a circuit board provided in

  On the other hand, in the method of sending the output of the torque detection means to a control box provided outside as in Patent Document 1, a weak output signal from the detector is sent via a cable, so that it is attenuated or exposed to noise. For this reason, there is a limit to the length of the cable that can be provided, for example, about 3 m is the limit. Therefore, in order to eliminate the cable length limitation, there has been a demand for processing the output of the torque detecting means inside the impact type screw fastening device and sending the detection result to an external device.

  In order to realize such a demand with an impact screw tightening device using a brushless DC motor, in addition to a circuit for processing the output from the torque detection means, a circuit equipped with a rotation control circuit for controlling the rotation of the motor The problem is where and how the substrate is placed.

  The present invention has been made in view of the above background, and an object of the present invention is to provide an impact-type screw fastening device in which a circuit board is efficiently arranged in a limited space, and is reduced in size and weight.

  Another object of the present invention is to provide an impact type screw tightening device that reduces the restriction on the transmission distance to the external device by converting the output signal from the torque detection means within the device and transmitting it to the external device. It is in.

  Still another object of the present invention is to provide an impact-type screw tightening device that detects a tightening torque and can determine in a tool body whether tightening has been performed as specified.

  Of the inventions disclosed in the present application, typical features will be described as follows.

According to one aspect of the present invention, a motor, a rotation control circuit for controlling the rotation of the motor, an impact unit driven by the motor, an output shaft connected to the shaft of the impact unit and mounted with a tip tool, In the impact-type screw tightening device having a housing that accommodates these, the housing includes a body portion that houses the motor and the impact unit, a grip portion that extends from the body portion in a substantially vertical direction and is gripped by an operator, It has a circuit board storage part provided at the tip of the grip part, and is configured to be separable on a surface passing through the body part, the grip part, and the circuit board storage part, and a plurality of circuit boards in the vertical direction with respect to the division surface of the circuit board storage part Are arranged side by side. In addition, a holding portion for holding the circuit board is provided on each side of the divided housing.
further,

  According to another feature of the present invention, there is provided torque detecting means for detecting the occurrence of tightening torque in the output shaft, and the detection circuit for detecting the detection signal of the torque detecting means and the rotation control circuit are provided separately in the circuit board housing portion. Mounted on the circuit board. Furthermore, a tightening torque value is calculated using a signal detected by the detection circuit, and a microcomputer for controlling the rotation of the motor using the tightening torque value is provided, and the microcomputer is provided on a circuit board different from the detection circuit. It was configured to be installed. The rotation control circuit is preferably arranged on a circuit board on the side close to the grip part in the circuit board housing part, and the detection circuit is preferably arranged on the circuit board opposite to the grip part with respect to the rotation control circuit.

  According to still another feature of the present invention, a transmission / reception circuit for transmitting / receiving data to / from an external device via a communication path is provided, and a tightening torque value calculated via the transmission / reception circuit is transmitted to the external device. In the circuit board housing part, from the side close to the grip part, the circuit board on which the rotation control circuit is mounted, the circuit board on which the detection circuit is mounted, and the circuit board on which the transmission / reception circuit is mounted are substantially perpendicular to the divided plane. Placed in parallel.

  According to the first aspect of the present invention, the housing is configured to be separable on a surface passing through the body portion, the grip portion, and the circuit board housing portion, and a plurality of circuit boards are arranged side by side in the vertical direction with respect to the dividing surface of the circuit board housing portion. Therefore, a plurality of circuit boards can be efficiently arranged in a limited space in the circuit board housing portion. Further, the position of the center of gravity can be optimized, and a screw tightening device that is easy for the operator to use can be realized.

  According to the invention of claim 2, since the holding portion for holding the circuit board is provided on each side of the divided housing, it is placed on the work table so that the inner surface of the housing on one side faces upward during assembly. Thus, the circuit board can be fixed by the holding part of the other housing simply by inserting the plurality of circuit boards into the holding part of the housing on one side and overlapping the other housing, so that the assembly of the circuit board part is improved.

  According to the invention of claim 3, the torque detection means for detecting the generation of the tightening torque in the output shaft is provided, and the detection circuit for detecting the detection signal of the torque detection means and the rotation control circuit are provided in the circuit board housing portion. Since it is mounted on the circuit board, it can avoid the problem of noise that occurs when the detection circuit that detects the detection signal of the torque detection means is combined with other circuit boards, so it is highly accurate torque detection without being affected by noise Can be realized.

  According to the invention of claim 4, there is provided a microcomputer for calculating the tightening torque value using the signal detected by the detection circuit and controlling the rotation of the motor using the tightening torque value. Therefore, the tightening torque value can be calculated inside the screw tightening device without disturbing the detection by the detection circuit due to the influence of noise.

  According to the invention of claim 5, the rotation control circuit is disposed on the circuit board on the side close to the grip part in the circuit board housing part, and the detection circuit is provided on the circuit board on the side opposite to the grip part with respect to the rotation control circuit. Since they are arranged, the wiring from the rotation control circuit to the motor and the wiring from the detection circuit to the external device can be wired at the shortest distance, and since they do not cross each other, it is possible to realize a favorable arrangement structure in terms of noise.

  According to the sixth aspect of the present invention, the transmission / reception circuit for transmitting / receiving to / from the external device via the communication path is provided, and the tightening torque value calculated via the transmission / reception circuit is transmitted to the external device. Therefore, the restriction on the length of the communication path is moderate, and an extremely long communication path can be realized as compared with the system in which the output from the torque detection means is sent to the external device as it is.

  According to the invention of claim 7, the circuit board on which the rotation control circuit is mounted, the circuit board on which the detection circuit is mounted, and the circuit board on which the transmission / reception circuit is mounted are arranged in parallel from the side close to the grip portion in the circuit board housing portion. Therefore, a plurality of circuit boards can be efficiently arranged in a limited space in the circuit board housing portion.

  The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the present specification, the vertical direction and the front-rear direction of the impact type screw fastening device 1 will be described as the directions shown in FIG. FIG. 1 is a diagram showing the entirety of an impact-type screw fastening device 1 according to an embodiment of the present invention, a power supply box 30 connected thereto, and an external connection device 40. The impact-type screw fastening device 1 is a cross-sectional view.

  The impact type screw tightening device 1 drives a motor 3 using electric power supplied from a power supply box 30 by a cable 2, drives an oil pulse unit 4 by the motor 3, and an output shaft connected to the oil pulse unit 4. By applying a rotational force and a striking force to 5, the rotational striking force is transmitted continuously or intermittently to a tip tool (not shown) such as a hexagon socket to perform operations such as nut tightening and bolt tightening.

  The power supplied by the cable 2 is, for example, DC 140V, and this DC power is generated from a commercial power supply 29 such as AC 100V in a power supply box 30 provided outside the tool body. In the power supply box 30, a DC 12 V power supply that is further insulated for the control system power supply is generated from the commercial power supply 29 and supplied to the impact screw fastening device 1 via the cable 2. Although not shown, the cable 2 includes a power cord for DC 140V and a power cord for DC 12V, and the cable 2, the impact type screw fastening device 1 and / or the power box 30 are not shown. It may be configured to be detachable using a connector, or may be configured to be detachable.

  The motor 3 is a brushless DC motor including a rotor 3b having a permanent magnet on the inner peripheral side and a stator 3a having a winding wound around an iron core on the outer peripheral side, and includes two bearings 10a and 10b. Thus, the rotary shaft 20 is fixed and accommodated in the cylindrical body 6a of the housing. The housing is composed of three parts, a body part 6a, a grip part 6b, and a circuit board housing part 6c, and is integrally manufactured from plastic or the like as an insulator. Further, the housing can be divided into left and right on the plane including the longitudinal axis of the body portion 6a and the longitudinal axis of the grip portion 6b, that is, the cross-sectional portion of FIG. Is done. A drive circuit board 7b for driving the motor 3 is disposed on the rear side of the motor 3, and an inverter circuit composed of a semiconductor element such as an FET and the rotation position of the rotor 3b are arranged on the circuit board. A rotational position detecting element 42 for detecting is mounted. As the rotational position detection element 42, for example, a Hall element or a Hall IC can be used. A cooling fan 17 for cooling the motor 3 and the oil pulse unit 4 is provided at the rearmost end inside the body portion 6a of the housing.

  A trigger switch 14a is disposed in the vicinity of the attachment portion of the grip portion 6b extending downward at a substantially right angle from the body portion 6a of the housing, and is proportional to the amount of the trigger switch 14a pulled by the switch circuit board 14b provided immediately below the trigger switch 14a. The signal is transmitted to the motor control board 7a. Inside the circuit board housing part 6c on the lower side of the grip part 6b, the three circuit boards of the motor control board 7a, the sensor board 8 and the communication board 9 are arranged in a direction substantially perpendicular to the dividing surface of the housing. Arranged in parallel. Guide grooves 21a, 21b, and 21c serving as portions for holding the circuit board are formed on the inner wall of the circuit board housing portion 6c of the housing. These guide grooves 21a, 21b, and 21c are similarly formed on the other side of the housing that can be divided. When assembling, the guide grooves 21a, 21b, and 21c are placed on the work table so that the inner surface of the housing on one side faces up. The three circuit boards can be easily fixed simply by inserting them into the guide grooves 21a, 21b, 21c of the housing and overlaying the other housing so that the three circuit boards are fitted into the guide grooves of the other housing.

  The communication board 9 is provided with a plurality of light emitting diodes (LEDs) 18, and the light from the light emitting diodes 18 is arranged so that it can be identified from the outside through a transmission window of a housing (not shown) or through a through hole. The light emitting diode 18 is turned on when the normal tightening is completed and the motor 3 is stopped, flashed as an alarm when it is determined that the tightening is abnormal, or turned on when a communication abnormality occurs.

  As the oil pulse unit 4 built in the body 6a of the housing, a known unit can be used. The oil pulse unit 4 is mainly synchronized with the drive portion that rotates in synchronization with the motor 3 and the output shaft 5 to which the tip tool is attached. Thus, the output part is composed of two parts that rotate. The drive portion that rotates in synchronization with the motor 3 includes a liner plate 23 that is directly connected to the rotary shaft 20 of the motor 3 and a liner 22 that has a substantially cylindrical outer diameter that is fixed so as to extend forward on the outer peripheral side thereof. . The output portion that rotates in synchronization with the output shaft 5 includes a main shaft 24 and a blade (not shown) that is attached to a groove formed 180 degrees apart on the outer peripheral side of the main shaft 24 via a spring. Is done. The main shaft 24 is penetrated by the integrally molded liner 22 and is held so as to be able to rotate in a closed space formed by the liner 22 and the liner plate 23, and oil for generating torque is generated in the closed space. (Hydraulic oil) is filled.

  When the trigger switch 14 a is pulled to start the motor 3, the rotational force of the motor 3 is transmitted to the oil pulse unit 4. When the oil pulse unit 4 is filled with oil and no load is applied to the output shaft 5 or when the load is small, the output shaft 5 is nearly rotated by the motor 3 only by the resistance of the oil. Rotate synchronously. When a strong load is applied to the output shaft 5, the rotation of the output shaft 5 and the main shaft 24 stops, and only the liner 22 on the outer peripheral side of the oil pulse unit 4 continues to rotate. The oil pressure rapidly rises to generate a shock pulse, and the main shaft 24 is rotated by a strong spire-like torque, and a large tightening torque is transmitted to the output shaft 5. Thereafter, the same striking operation is repeated several times, and the fastening target is tightened with the set torque. The output shaft 5 is held at the rear end by the bearing 10 c and the front is held by the case 15 by the metal 16.

  The diameter of the output shaft 5 is thin on the front side of the bearing 10c, and a strain gauge 12 as a torque detection sensor is attached to the thinned portion. On the front side of the location where the strain gauge 12 is attached, the diameter of the output shaft 15 is thick, and the input transformer 11a for supplying voltage to the strain gauge 12 at that location and the output from the strain gauge 12 are transmitted. An output transformer 11b is provided. The input transformer 11a and the output transformer 11b include coils disposed on the inner peripheral side and the outer peripheral side, respectively. The inner peripheral side coil is fixed to the output shaft 5, and the outer peripheral side coil is fixed to the case 15. Input / output voltages to the input transformer 11a and the output transformer 11b are transmitted to the sensor substrate 8 via the connector 11c. Each part mentioned above attached to the output shaft 5 is integrated in the cylindrical case 15, and the case 15 is attached to the front side of the trunk | drum 6a of a housing. In addition, a wiring cover 19 for covering connection wiring and the like is provided at the lower portion of the case 15.

  Next, the mounting structure of the rotational position detection sensor and the torque detection sensor will be described with reference to FIG. FIG. 2 is a cross-sectional view taken along a line AA in FIG. The wiring cover 19 is a cover for forming a space through which a wiring (not shown) for the torque detection sensor passes. Here, as can be understood from FIG. 2, only the position where the strain gauge 12 is attached to the cylindrical output shaft 5 has a small diameter and a substantially square cross section. And the strain gauge 12 was provided in each of the four planes located in the outer periphery of a cross section. Thereby, the detection accuracy of torque can be improved.

  Next, the configuration and operation of the drive control system of the motor 3 will be described with reference to FIG. FIG. 3 is a block diagram showing a circuit configuration of the drive control system of the motor 3. In the present embodiment, the motor 3 is a three-phase brushless DC motor. This brushless DC motor is a so-called inner rotor type, and includes a rotor (rotor) 3b including a plurality of sets of permanent magnets (magnets) including N and S poles, and a star-connected three-phase motor. In order to detect the rotational position of the stator 3a (stator) composed of the stator windings U, V, and W and the rotor 3b, three rotations arranged at predetermined intervals in the circumferential direction, for example, at an angle of 60 ° A position detection element 42 is provided. Based on the position detection signals from these rotational position detection elements 42, the energization direction and time to the stator windings U, V, W are controlled, and the motor 3 rotates.

  The drive circuit substrate 7b is configured to include an inverter circuit including six switching elements Q1 to Q6 such as FETs (Field Effect Transistors) connected in a three-phase bridge form. The gates of the six switching elements Q1 to Q6 that are bridge-connected are connected to the rotation control circuit 51, and the drains or sources of the six switching elements Q1 to Q6 are star-connected stator windings U. , V, W. As a result, the six switching elements Q1 to Q6 perform a switching operation according to the switching element drive signals (drive signals H1 to H6) input from the rotation control circuit 51, and the 140V DC applied to the inverter circuit is three-phased. (U phase, V phase and W phase) Electric power is supplied to the stator windings U, V and W as voltages Vu, Vv and Vw.

  Of the switching element drive signals (three-phase signals) for driving the gates of the six switching elements Q1 to Q6, the three negative power supply side switching elements Q4, Q5, Q6 are converted into pulse width modulation signals (PWM signals) H4, The operation amount (stroke) of the trigger switch 14a is detected by the applied voltage setting circuit 49, and a setting signal based on the operation amount is output to the first microcomputer 50 for motor control. The microcomputer 50 adjusts the amount of power supplied to the motor 3 by changing the pulse width (duty ratio) of a PWM (Pulse Width Modulation) signal, and controls the start / stop of the motor 3 and the rotation speed.

  Here, the PWM signal is supplied to any one of the positive power supply side switching elements Q1 to Q3 or the negative power supply side switching elements Q4 to Q6 of the inverter circuit, and the switching elements Q1 to Q3 or the switching elements Q4 to Q6 are switched at high speed. As a result, the power supplied to each stator winding U, V, W is controlled by 140V DC. In this embodiment, since the PWM signal is supplied to the negative power supply side switching elements Q4 to Q6, the electric power supplied to the stator windings U, V, W by controlling the pulse width of the PWM signal. Can be adjusted to control the rotation speed of the motor 3.

  Although not shown, the microcomputer 50 has a central processing unit (CPU) for outputting a drive signal based on the processing program and data, a ROM for storing the processing program and control data, and a temporary storage for data. It includes a RAM, a timer having a clock function, and the like. Although details will be described later, 140 V direct current that is not insulated is supplied directly or after being stepped down to the circuit shown in FIG.

  Next, the overall configuration of the circuit of the impact type screw fastening device 1 according to the embodiment of the present invention will be described with reference to FIG. In the impact type screw tightening device 1 according to the present embodiment, the motor system power source is divided into two systems, that is, a motor system power source serving as a power source for the motor 3 and the motor control circuit, and a control power source for other control devices. Thus, the control system power supply is driven by an insulated power supply.

  Two direct currents are supplied from the power supply box 30 provided outside to the entire circuit 1 </ b> A incorporated in the impact-type screw fastening device via the cable 2. One is a 140 V DC that is not insulated from the AC power supply 29 and a 12 V DC that is insulated from the AC power supply 29. The 140 V direct current is generated by the full-wave rectifying / smoothing circuit 31 in the power supply box 30. The full-wave rectifying / smoothing circuit 31 is, for example, a combination of a rectifying circuit in which four rectifying elements are connected in a bridge shape and a smoothing circuit using a capacitor. In this embodiment, a transformer is not used. Insulated state. The 12V direct current is generated by an AC / DC converter 32 arranged in the power supply box 30. In this embodiment, the AC / DC converter 32 uses a known device whose output is insulated.

  In the circuit 1A, 140V direct current is supplied to the drive circuit board 7b of the motor 3. Drive power is supplied to a stator winding of a predetermined motor 3 by an inverter circuit mounted on the drive circuit board 7b. The 140V direct current is also supplied to the 18V constant voltage circuit 53. The 18V constant voltage circuit 53 is not insulated and generates a DC voltage of 18V from a DC power supply of 140V, and may be constituted by a known chopper circuit or a known constant voltage combining a Zener diode and a transistor. You may comprise with a circuit. Next, the non-insulated 18V direct current output from the 18V constant voltage circuit 53 is input to the second constant voltage circuit 52, and the second constant voltage circuit 52 operates the operation voltage Vcc for operating the microcomputer 50, for example, 5V DC and 3.3V DC are generated. As is apparent from FIG. 4, the motor 3 and the motor control circuit are all driven using a non-insulated DC 140V.

  The insulated 12V DC power generated by the power supply box 30 is input to a portion other than the control circuit for the motor 3. First, the 12V DC power supply is input to the constant voltage circuit 64, where a voltage for operating the microcomputer 60, for example, 5V, 3.3V is generated and input to the microcomputer 60. Also. Input to ± 12 V power supply 71. The ± 12V power supply 71 generates a voltage of −12V in addition to + 12V. −12V is used for driving the strain gauge 12. Note that the power supply line from the ± 12 V power supply 71 to the strain gauge 12 is not shown.

  The 12 V direct current is also supplied to the cooling fan 17. The cooling fan 17 is ON / OFF controlled by the drive circuit 72 under the control of the microcomputer 60. Here, the reason why the cooling fan 17 is driven by the insulated 12 V direct current is that the microcomputer 60 for controlling the cooling fan 17 is driven by the insulated power source. In addition, if the cooling fan 17 is controlled by the microcomputer 50, the power source of the non-insulated constant voltage circuit 53 can be used. However, the cooling fan 17 is formed with an air inflow port, an air outflow port, and the like, and dust and dust may enter inside. In addition, since the mounting position of the cooling fan 17 is located at the rear end of the main body 6a of the housing 6, the cooling fan 17 is driven by an insulated power source in order to minimize the possibility of accidental touching. Is preferred.

  A transmission signal from the transmission circuit 70a of the torque detection circuit 70 is supplied to the strain gauge 12 via the input transformer 11a. At the same time, the reference amplitude from the transmission circuit 70a is also sent to the microcomputer 2. This is because the microcomputer 2 cannot detect distortion from the torque waveform without inputting the reference amplitude. When tightening torque is generated by the oil pulse unit 4 on the output shaft 5, the resistance value of the strain gauge 12 changes, and the reference amplitude signal changed by the change in resistance value is transmitted to the detection circuit 70b via the output transformer 11b. It is detected. Since a signal for offset adjustment is sent from the microcomputer 60 to the detection circuit 70b, the detection signal corrected for offset is output to the microcomputer 60. In the conventional device, the detection circuit 70b is provided in the external connection device 40. However, in the present embodiment, the torque detection circuit 70 including the detection circuit 70b is provided inside the impact type screw fastening device 1.

  The microcomputer 60 uses the output value of the strain gauge 12 to calculate how much torque value has been tightened (tightening torque), so that the tightening torque value is calculated inside the impact type screw tightening device 1. Can do. Usually, the reference amplitude signal deformed by the change in the resistance value of the strain gauge 12 has a very small signal level and is easily influenced by external noise. In the present embodiment, since the distance from the strain gauge 12 to the detection circuit 70b can be short, detection can be performed while suppressing the influence of noise as much as possible. Furthermore, since the detection circuit 70 is mounted on a circuit board different from the microcomputers 50 and 60, the influence of noise can be further reduced.

  The first microcomputer 50 and the second microcomputer 60 are connected via a signal line to exchange data between them, but the signal line is connected via a photocoupler 65 in order to maintain the insulation relationship between the two. . Signals sent from the second microcomputer 60 to the first microcomputer 50 are a signal 68 for setting the rotational driving force of the motor 3 and an ON / OFF control signal 69 for turning off the rotation of the motor 3. The data sent from the first microcomputer 50 to the second microcomputer 60 is a signal 66 indicating whether or not the trigger 8 is turned on and an Acknowledge signal 67 for the signal 68 for setting the rotational driving force of the motor 3. Of course, the type of signal is not limited to this, and the exchange of other signals is arbitrary.

  Next, the operation | movement at the time of bolt fastening using the impact type screw fastening apparatus 1 of this embodiment is demonstrated. First, the operator operates an operation button (not shown) of the main body, and an operator who sets a tightening torque value sets a bolt or the like on the tip tool and positions the material to be fastened, and then pulls the trigger switch 14a. The microcomputer 50 controls the motor 3 to rotate in accordance with the drawn stroke. At this time, the microcomputer 60 may limit the rotation speed of the motor 3 according to the set tightening torque. For example, when the tightening torque is low, the microcomputer 60 corresponds to the microcomputer 50 with a low tightening torque. The maximum rotation number of the motor 3 is instructed. When the rotation speed of the motor 3 is limited as described above, the microcomputer 50 is instructed to rotate the motor 3 even when the stroke of the trigger switch 14a corresponds to a higher rotation speed. Control to be kept at.

  Next, the microcomputer 60 monitors the output of the strain gauge 12 to monitor whether the tightening has been performed with a predetermined tightening torque. If the microcomputer 60 determines that the tightening has been normally completed with the set tightening torque value, the microcomputer 60 sends a signal for turning off the motor 3 to the microcomputer 50 via the signal line 69. When the microcomputer 50 receives the instruction to turn off the motor, the microcomputer 50 stops the rotation of the motor 3 even though the trigger switch is turned on. The operator can recognize that the work is completed by the automatic stop of the motor 3.

  The microcomputer 60 can exchange various data with the external connection device 40 via the transceiver 61. In this case, the transceiver 61 and the external connection device 40 are connected using the signal line 44. The cable 2 including the signal line 44 is detachably connected by the connector 43 and is connected to the power supply box 30 and the external connection device 40. The communication using the signal line 44 may use a known wireless communication system instead of a wired communication system.

  In the overall circuit 1A described above, in the present embodiment, the sensor board 8 for torque sensor to which a minute signal is inputted and processed is replaced with another circuit board (a motor control board 7a, a drive circuit board 7b, a communication board). Since it is mounted on a circuit board different from the board 9), it is possible to effectively prevent the disadvantage of the torque sensor that noise is increased and malfunction is likely to occur. Moreover, since this circuit board is used as a separate board and separately mounted on the housing separately from the other circuit boards, a plurality of circuit boards can be efficiently arranged in a limited space.

  As mentioned above, although demonstrated based on embodiment which shows this invention, this invention is not limited to the above-mentioned form, A various change is possible within the range which does not deviate from the meaning. For example, if the problem of noise can be cleared, the sensor substrate 8 may be realized on the same circuit board as other circuit boards. The present invention can also be applied to a screw tightening device using a secondary battery as a power source. In that case, a plurality of circuit boards are divided and arranged in the information of the circuit board housing portion 6c, and a secondary battery is provided below the circuit board. A battery pack may be attached.

It is sectional drawing which shows the whole impact type screw fastening apparatus which concerns on embodiment of this invention. It is sectional drawing of the AA part of FIG. 3 is a block diagram showing a circuit configuration of a drive control system of a motor 3. FIG. It is a figure which shows the whole circuit structure of the impact type screw fastening apparatus 1 which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Impact type screw fastening apparatus 1A Overall circuit 2 (built in) 2 Cable 3 Motor 3a Motor stator 3b Motor rotor 4 Oil pulse unit 5 Output shaft 6a (Housing) Body part 6b (Housing) grip part
6c (Housing) circuit board housing portion 7a Motor control board 7b Drive circuit board 8 Sensor board 9 Communication board
10a, 10b, 10c Bearing
11a Input transformer 11b Output transformer 11c Connector 12 Strain gauge 14a Trigger switch 14b Switch circuit board 15 Case 16 Metal 17 Cooling fan
DESCRIPTION OF SYMBOLS 18 Light emitting diode 19 Wiring cover 20 Rotating shaft 21a, 21b, 21c Guide groove 22 Liner 23 Liner plate 24 Main shaft 29 Commercial power supply 30 Power supply box 31 Full wave rectification smoothing circuit 32 AC / DC converter 40 External connection apparatus 42 Rotation position detection element 43 Connector 47 Inverter circuit 49 Applied voltage setting circuit 50 Microcomputer 51 Rotation control circuit 52 Constant voltage circuit 53 18V constant voltage circuit 60 Microcomputer 61 Transceiver 64 Constant voltage circuit 65 Photocoupler 66, 67, 68, 69 Signal line 70 Torque detection circuit 70a Transmission circuit 70b (within the torque detection circuit) Detection circuit 71 (within the torque detection circuit) 71 ± 12V power supply

Claims (7)

A motor, a rotation control circuit for controlling the rotation of the motor, an impact unit driven by the motor, an output shaft connected to a shaft of the impact unit and mounted with a tip tool, and a housing for housing them; In impact type screw tightening device,
The housing includes a body portion that houses the motor and the impact unit, a grip portion that extends in a substantially vertical direction from the body portion and is gripped by an operator, and a circuit board housing that is provided at the tip of the grip portion. Part
The housing is configured to be separable on a surface passing through the body portion, the grip portion, and the circuit board housing portion,
An impact-type screw fastening device, wherein a plurality of circuit boards are arranged side by side in the vertical direction with respect to the surface of the circuit board housing portion.   The impact type screw tightening device according to claim 1, wherein a holding portion for holding the circuit board is provided on each side of the divided housing. Providing a torque detection means for detecting the generation of tightening torque in the output shaft;
The impact type screw tightening according to claim 1 or 2, wherein the detection circuit for detecting the detection signal of the torque detection means and the rotation control circuit are mounted on another circuit board in the circuit board housing portion. apparatus. A tightening torque value is calculated using the signal detected by the detection circuit, and a microcomputer for controlling the rotation of the motor using the tightening torque value is provided,
4. The impact type screw tightening device according to claim 3, wherein the microcomputer is mounted on a circuit board different from the detection circuit. The rotation control circuit is disposed on a circuit board on the side close to the grip part in the circuit board housing part,
The impact type screw tightening device according to claim 4, wherein the detection circuit is arranged on a circuit board opposite to the grip portion with respect to the rotation control circuit.   6. The impact type screw tightening according to claim 5, wherein a transmission / reception circuit for transmitting / receiving to / from an external device via a communication path is provided, and the tightening torque value calculated via the transmission / reception circuit is transmitted to the external device. apparatus.   A circuit board on which the rotation control circuit is mounted, a circuit board on which the detection circuit is mounted, and a circuit board on which the transmission / reception circuit is mounted are arranged in parallel from the side close to the grip section in the circuit board storage section. The impact type screw fastening apparatus according to claim 6.

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