Electric driver system and driver control device

Abstract

To provide an electric driver system and a driver control device which can properly control operation of an electric driver.SOLUTION: The electric driver system comprises an electric driver 2 and a driver control device 3. The electric driver 2 has a motor 21, and consumption current value detecting means 12 that detects, as a consumption current value, a current value of the motor 21. The driver control device 3 has: current value obtaining means 33 that obtains a consumption current value transmitted from the electric driver 2; screw- fastening state determining means 33 that determines a screw-fastening state by the electric driver 2, on the basis of the consumption current value; and memorizing means 32 that memorizes a correction value set on the basis of the consumption current value of the electric driver and a torque value which are sampled and a determination value set on the basis of the sampled torque value. The screw-fastening state determining means 33 determines the screw-fastening state, by comparing a torque value calculated based on the consumption current value and the correction value with the determination value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an electric screwdriver system and a driver control device. [Background technology]

[0002] Various electric screwdrivers have been proposed for efficiently tightening screws, etc. In these types of electric screwdrivers, a mechanical or electromagnetic clutch mechanism is provided between the motor and a driver chuck, which is fitted with a driver bit for tightening the screw, and when the screw is tightened and the screw seating surface is seated and the screw tightening torque reaches a set value or more, the motor drive is stopped or the motor drive is interrupted, enabling more precise tightening (for example, Patent Documents 1 and 2).

[0003] Also, an electric screwdriver system has been proposed that determines defects such as insufficient or excessive screw tightening, screw puncture, galling, and head stripping by taking into account the screw tightening time in addition to the rotational torque of the motor (for example, Patent Document 3).Furthermore, an electric screwdriver system has been proposed that diagnoses whether a screw has been tightened correctly based on the pressing force generated by the electric screwdriver pressing against the screw in addition to the rotational torque and screw tightening time of the electric screwdriver (for example, Patent Document 4).

[0004] However, in the electric screwdriver systems described in Patent Documents 3 and 4, a torque sensor is mounted on the electric screwdriver, the rotational torque of the motor is detected by the torque sensor, and the screw tightening state is determined based on the detected rotational torque. However, torque sensors are expensive, and there is a problem in that such an expensive torque sensor needs to be mounted on each electric screwdriver.

[0005] Therefore, there is a demand for an electric screwdriver system that can properly determine the screw tightening state even in an electric screwdriver that does not have a torque sensor. Patent document 5 discloses a configuration in which the current generated in the AC power supply of the slave station is obtained as a motor current I, this motor current I is converted into a torque value using a pre-stored I / T conversion coefficient K, and the converted torque value is used to detect operational abnormalities of the electric screwdriver.

[0006] However, in Patent Document 5, the current supplied from the driver control device to the electric screwdriver is designated as motor current I, and the torque value is calculated based on this motor current I, but the current value of this motor current I does not necessarily match the current value of the current actually consumed by the motor of the electric screwdriver (hereinafter referred to as current consumption value), resulting in the problem that the torque value of the electric screwdriver cannot be calculated with high accuracy. Specifically, even if the current value of the current supplied from the driver control device to the electric screwdriver is constant, the current consumption value actually consumed by the motor of the electric screwdriver changes depending on the influence of noise generated by the motor of the electric screwdriver, the type of screw (screw diameter size, screw material, etc.), the condition of the mounting member to which the screw is attached (hole size of the mounting member, material of the mounting member, etc.), the condition of the electric screwdriver 2 (model of the electric screwdriver 2, type of motor 21 of the electric screwdriver 2, deterioration state of the electric screwdriver 2 over time, wear state of each part of the electric screwdriver 2), etc., resulting in the problem that the torque value cannot be calculated appropriately. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 3663638 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-238418 [Patent Document 3] Patent No. 4295063 [Patent Document 4] Japanese Patent Application Laid-Open No. 2011-173233 [Patent Document 5] Patent No. 6038397 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention was created in view of the above circumstances, and aims to provide an electric screwdriver system and a driver control device that can control the operation of an electric screwdriver with high precision. [Means for solving the problem]

[0009] An electric driver system according to a first aspect of the present invention is an electric driver system having an electric driver and a driver control device that controls the operation of the electric driver, wherein the electric driver has a motor, a current consumption value detection means that detects a current value of the motor as a current consumption value, and a transmission means that transmits the current consumption value to the driver control device, and the driver control device has a current value acquisition means that repeatedly acquires the current consumption values ​​transmitted from the electric driver by the transmission means in a chronological order, and a screw tightening state determination means that determines the state of screw tightening by the electric driver based on the current consumption value acquired by the current value acquisition means, The device has an output means for announcing or externally outputting the judgment result by the screw tightening state judgment means, and a memory means for storing a correction value for converting the current consumption value into a torque value, which is set based on the current consumption value and torque value of the electric screwdriver sampled during normal screw tightening work, and for storing a torque value for determining that screw tightening is complete, which is set based on the sampled torque value, as a judgment value.The screw tightening state judgment means judges the screw tightening state by comparing the torque value calculated based on the current consumption value and the correction value acquired by the current value acquisition means with the judgment value stored in the memory means. In the above electric screwdriver system, the correction value is not a uniform numerical value, but a numerical value set for each current consumption value based on the sampled current consumption value and torque value of the electric screwdriver, the memory means stores the correction value for each current consumption value, and the screw tightening state determination means can be configured to convert the current consumption value to the torque value using the correction value corresponding to the current consumption value. An electric driver system according to a second aspect of the present invention is an electric driver system having an electric driver and a driver control device that controls the operation of the electric driver, wherein the electric driver has a motor, a current consumption value detection means that detects the current value of the motor as a current consumption value, and a transmission means that transmits the current consumption value to the driver control device, and the driver control device has a current value acquisition means that repeatedly acquires the current consumption values ​​of the electric driver transmitted from the electric driver by the transmission means in a chronological order, a screw tightening state determination means that determines the state of screw tightening by the electric driver based on the current consumption values ​​acquired by the current value acquisition means, an output means that notifies or externally outputs the result of the determination by the screw tightening state determination means, and a memory means that stores a current consumption value for determining that screw tightening is complete as a determination value, the current consumption value being set based on the electric driver's current consumption values ​​sampled during normal screw tightening work, and the screw tightening state determination means determines the state of screw tightening by comparing the current consumption value acquired by the current value acquisition means with the determination value stored in the memory means. In the above electric screwdriver system, when two or more torque values ​​are required in a series of work processes for tightening multiple screws, the memory means stores two or more judgment values ​​corresponding to the two or more required torque values ​​for each task in the series of work processes, and the screw tightening state judgment means can be configured to convert the current consumption value of the electric screwdriver into the torque value and compare the converted torque value with the judgment value for each task in the series of work processes to judge the screw tightening state. In the above electric screwdriver system, the memory means has a function of updating the correction value when the sampling is newly performed, and the screw tightening state determination means can be configured to convert the torque value using the updated correction value when the correction value is updated, and determine the screw tightening state. In the above electric screwdriver system, the memory means stores the judgment value for each screw tightening condition by sampling the current consumption value and / or torque value of the electric screwdriver for each screw tightening condition consisting of a combination of at least the type of screw and / or the type of mounting member to which the screw is attached, and the screw tightening state judgment means can be configured to acquire information on the screw tightening conditions under which the screw is to be tightened, and judge the screw tightening state using the judgment value corresponding to the acquired screw tightening condition. In the above electric screwdriver system, the memory means stores, during the sampling, a time period including the time from when the screw tightening starts until a peak in the torque value or current consumption value is formed as the seating surface of the screw collides with the opening of the screw hole as a normal judgment time period, and the screw tightening state judgment means calculates, based on the current consumption value of the electric screwdriver, the time from when the screw tightening starts until a peak in the current consumption value or torque value is formed as the seating surface of the screw collides with the opening of the screw hole, and can be configured to judge that there is an abnormality in the screw tightening operation if the calculated time falls outside the normal judgment time period. A driver control device according to a first aspect of the present invention is a driver control device that has a motor and is electrically connected to an electric screwdriver that detects the current value of the motor as a current consumption value, and controls the operation of the electric screwdriver, and includes: a current value acquisition means that repeatedly acquires the current consumption value of the electric screwdriver in a chronological order from the electric screwdriver; a screw tightening state determination means that determines the state of screw tightening by the electric screwdriver based on the current consumption value acquired by the current value acquisition means; an output means that notifies or externally outputs the determination result of the screw tightening state determination means; and a memory means that stores a correction value for converting the current consumption value into a torque value, which is set based on the current consumption value and torque value of the electric screwdriver sampled during normal screw tightening work, and stores a torque value for determining that screw tightening is complete, which is set based on the sampled torque value, as a determination value, and the screw tightening state determination means determines the state of screw tightening by comparing the torque value calculated based on the current consumption value and the correction value acquired by the current value acquisition means with the determination value stored in the memory means. A driver control device according to a second aspect of the present invention is a driver control device that has a motor, is electrically connected to an electric screwdriver that detects the current value of the motor as a current consumption value, and controls the operation of the electric screwdriver, and has: a current value acquisition means that repeatedly acquires the current consumption value of the electric screwdriver in a chronological order from the electric screwdriver; a screw tightening state determination means that determines the screw tightening state of the electric screwdriver based on the current consumption value acquired by the current value acquisition means; an output means that notifies or externally outputs the determination result of the screw tightening state determination means; and a memory means that stores a current consumption value for determining that screw tightening is complete as a determination value, which is set based on the current consumption value of the electric screwdriver sampled during normal screw tightening work, and the screw tightening state determination means determines the screw tightening state by comparing the current consumption value acquired by the current value acquisition means with the determination value stored in the memory means. [Effects of the Invention]

[0010] According to the present invention, the operation of the drive driver can be controlled with high precision. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram of an electric screwdriver system according to an embodiment of the present invention. [Figure 2] 1 is a functional block diagram of an electric screwdriver system according to an embodiment of the present invention. [Figure 3] 1 is a graph showing an example of IT characteristics under a constant voltage. [Figure 4] 10 is a graph showing the relationship between the tightening state of a screw and the torque and current consumption value of an electric screwdriver during normal screw tightening work. [Figure 5] 10A and 10B are diagrams for explaining a method for diagnosing an abnormality in a screw tightening operation. [Figure 6] FIG. 10 is a configuration diagram of an electric screwdriver system according to another embodiment. [Figure 7] 10 is an example of a setting unit, a display unit, and a notification unit of an electric screwdriver system according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of an electric screwdriver system according to the present invention will be described below with reference to the drawings. Fig. 1 is a configuration diagram of an electric screwdriver system 1 according to this embodiment. As shown in Fig. 1, the electric screwdriver system 1 according to this embodiment has an electric screwdriver 2 and a driver control device 3, and the electric screwdriver 2 and the driver control device 3 are electrically connected via a power cord 4 and a signal cord 5.

[0013] The electric screwdriver system 1 according to this embodiment is a system characterized in that a driver control device 3 controls the operation of the electric screwdriver 2 based on the current consumption value of the electric screwdriver 2. The inventor has conducted extensive research over many years in order to use the current consumption value of the electric screwdriver 2 to control the operation of the electric screwdriver 2 and diagnose abnormalities, and has invented a method of judging the screw tightening state based on the rotational torque by incorporating a torque sensor in the electric screwdriver and using the torque sensor to detect the rotational torque of the motor 21 (see, for example, Patent Document 4). However, the method using a torque sensor requires a torque sensor in each electric screwdriver, which causes problems such as a complex configuration of the electric screwdriver and an increase in the price of the entire system.

[0014] In response to these problems, the inventors conducted further research and came up with the idea of ​​calculating a torque value based on the current consumption value of the electric screwdriver 2 and controlling the operation of the electric screwdriver 2 based on the calculated torque value. Specifically, because there is a proportional relationship between the current consumption value and torque value of the motor 21, known as the IT characteristic, the inventors conceived the idea of ​​calculating a torque value by multiplying the current consumption value by a uniform correction value and controlling the operation of the electric screwdriver based on this torque, and created a testing machine. However, when the operation of the electric screwdriver using the testing machine was confirmed, it was found that due to the influence of noise generated by the motor 21, the current consumption value and torque were not accurately proportional to each other, and the torque calculated based on the current consumption value deviated from the actual torque value by an average of about 20%. At a practical level, an error of several percent to 5% is required, and it was found that this method could not be used in practice as it was.

[0015] Therefore, the inventors created a configuration in which the current consumption value of the electric screwdriver is sampled, the current consumption value when screw tightening is completed normally is set as a current judgment value, and when the current consumption value of the electric screwdriver 2 during actual screw tightening work reaches the current judgment value, it is judged that the screw tightening work is completed. In this way, by sampling the current consumption value of the electric screwdriver 2 and setting the current judgment value, it has become possible to appropriately judge the screw tightening state based on the current consumption value of the electric screwdriver 2 without being affected by noise from the motor 21.

[0016] On the other hand, the required specifications for screw tightening work may instruct that screws be tightened at a specified torque value, such as 5 Nm, and in the above configuration, which simply determines whether the screw tightening work has been completed based on the current consumption value, there is a problem in that the torque value is not associated with the current consumption value, and it is not possible to determine whether the screw has been tightened at the specified torque value.

[0017] Therefore, in this embodiment, an electric screwdriver and a torque tester are used. The conditions of the actual screw tightening operation (the type of screw and the mounting material used in the actual screw tightening operation) are reproduced on the torque tester, and the electric screwdriver 2 used in the actual screw tightening operation is sampled to acquire the torque value during screw tightening from the torque tester. Then, for each electric screwdriver 2 consumption value, a correction value for converting the electric screwdriver 2 consumption value to a torque value is calculated, and the correction value for each electric screw consumption value is stored in the driver control device 3. Thus, simply by acquiring the electric screwdriver 2 consumption value during screw tightening, the driver control device 3 can appropriately calculate the torque value of the electric screwdriver 2 based on the acquired current consumption value, and determine whether the screw was tightened at a predetermined torque value. In this way, by calculating the torque value using the correction value set for each current consumption value for the electric screwdriver 2 consumption value, it is possible to keep the error in the torque value to 5% or less. The configuration of the electric screwdriver system according to this embodiment is described below.

[0018] Fig. 2 is a functional block diagram of the electric screwdriver 2 and the driver control device 3. As shown in Fig. 2, the electric screwdriver 2 mainly has a control unit 10 and a drive unit 20. The control unit 10 and the drive unit 20 are integrally housed within a housing 30 of the electric screwdriver 2. Details of each component of the electric screwdriver 2 will be explained below.

[0019] First, we will explain the control unit 10. The control unit 10 has a function of controlling the operation of the motor 21, and as shown in Fig. 2, it mainly has a motor drive control unit 11, a current consumption value measurement unit 12, a lever switch 13, and a push switch 14.

[0020] The motor drive control unit 11 controls the driving of the motor 21. In this embodiment, the motor drive control unit 11 drives the motor 21 by applying an electric current supplied from the driver control device 3 to the motor 21 while receiving switch-on signals for driving the motor 21 from the lever switch 13 and the push switch 14. The lever switch 13 is a switch that the user can press to operate the electric screwdriver 2, and when the user presses the lever switch 13, it transmits a switch-on signal to the motor drive control unit 11. The push switch 14 is turned on when the user presses the driver bit 26 against a screw, and when turned on, it transmits a switch-on signal to the motor drive control unit 11.

[0021] In this embodiment, the applied current applied from the driver control device 3 to the electric screwdriver 2 is limited, and the motor drive control unit 11 drives the motor 21 based on the limited applied current value, thereby preventing the torque of the electric screwdriver 2 from exceeding the torque limit range. Also, the driver control device 3 can stop the application of the applied current to the electric screwdriver 2, thereby stopping the driving of the motor 21 by the motor drive control unit 11.

[0022] The current consumption value measuring unit 12 has a circuit for measuring the current actually consumed by the motor 21 of the electric screwdriver 2, and repeatedly measures the value of the current consumed by the motor 21 of the electric screwdriver 2 as the current consumption value of the electric screwdriver 2. In addition, the current consumption value measuring unit 12 transmits the measured current consumption value of the electric screwdriver 2 to the driver control device 3 via the signal code 5 as needed.

[0023] Here, the applied current value, which is the value of the current applied by the driver control device 3 to the electric screwdriver 2, and the consumed current value, which is the value of the current actually flowing through the motor 21 of the electric screwdriver 2 based on the applied current applied by the driver control device 3, do not necessarily match. Even if the applied current value is constant, the transmission efficiency may change depending on the influence of noise generated by the motor 21 of the electric screwdriver 2, the screw tightening conditions, and the like, and the consumed current value actually consumed by the motor 21 may change. In this embodiment, the torque value of the electric screwdriver 2 can be calculated with high accuracy by calculating the torque value based on the consumed current value actually consumed by the motor 21 of the electric screwdriver 2. Note that in this embodiment, examples of screw tightening conditions include the type of screw (screw diameter, length, material of the screw, etc.), the type of mounting member to which the screw is attached (diameter of the hole drilled in the mounting member, material of the mounting member, etc.), and the condition of the electric screwdriver 2 (model of the electric screwdriver 2, type of motor 21 of the electric screwdriver 2, deterioration over time of the electric screwdriver 2, wear of each part of the electric screwdriver 2, etc.).

[0024] In this embodiment, the current measurement circuit of the current consumption measurement unit 12 can be configured to incorporate a filter circuit to reduce measurement errors in the current consumption value due to voltage noise or current noise. The filter circuit is not particularly limited, but a circuit incorporating a CR wrench circuit at the input of an operational amplifier can be used. This allows the current consumption measurement unit 12 to more accurately measure the current consumption value of the electric screwdriver 2. However, using such a filter circuit alone cannot sufficiently eliminate the error between the motor's rotational torque and the current consumption value. Therefore, in this embodiment, as described below, a correction value for converting the current consumption value to a torque value is calculated based on the current consumption value and torque value sampled during actual screw tightening work. This allows the torque value to be accurately calculated from the current consumption value of the electric screwdriver 2 even when there is noise, and the screw tightening state can be accurately determined based on the calculated torque value.

[0025] Next, we will explain the drive unit 20. As shown in Fig. 2, the drive unit 20 has a motor 21, a reducer 22, a bit holder 24, a chuck 25, and a driver bit 26, and drives the motor 21 based on the control of the control unit 10, thereby rotating the driver bit 26.

[0026] The motor 21 is driven to rotate under the control of the motor drive control unit 11. In this embodiment, a DC motor is used as the motor 21, and a driver bit 26 provided at the tip of the electric screwdriver 2 is rotated by the rotation of the motor 21. In addition, a reducer 22 made of a planetary gear that reduces the rotation speed of the motor 21 is provided between the motor 21 and the driver bit 26, and the driver bit 26 is attached to the reducer 22 via a bit holder 24 and a chuck 25.

[0027] Next, the driver control device 3 according to this embodiment will be described. The driver control device 3 is a device for controlling the operation of the electric screwdriver 2. In this embodiment, the driver control device 3 controls the operation of the electric screwdriver 2 by controlling the current applied to the electric screwdriver 2. The driver control device 3 will be described in detail below.

[0028] As shown in Fig. 2, the driver control device 3 mainly includes a power supply unit 31, a memory unit 32, a driver control unit 33, a setting unit 34, a display unit 35, and a notification unit 36. Note that, although the example shown in Figs. 1 and 2 illustrates a configuration in which one electric screwdriver 2 is connected to one driver control device 3, the configuration is not limited to this, and multiple electric screwdrivers 2 can be connected to one driver control device 3.

[0029] The power supply unit 31 is connected to a commercial power source to obtain power for operating the driver control device 3, and supplies power for operating the electric screwdriver 2 to the electric screwdriver 2 via the power cord 4. The supply of power from the power supply unit 31 to the electric screwdriver 2 is controlled by a driver control unit 33.

[0030] Next, we will explain the driver control unit 33. The driver control unit 33 controls the screw tightening operation of the electric screwdriver 2 by controlling the current applied to the electric screwdriver 2. Specifically, the driver control unit 33 mainly has the following eight functions. (1) A driver driving function that drives the electric screwdriver 2 by applying an electric current to the electric screwdriver 2. (2) A current consumption value acquisition function that acquires the current consumption value of the motor 21 from the electric driver 2. (3) A torque conversion function that converts the current consumption value obtained from the electric screwdriver 2 into the torque of the electric screwdriver 2. (4) A torque limiting function that limits the torque of the electric screwdriver 2 by limiting the current applied to the electric screwdriver 2, regardless of whether the electric screwdriver 2 has a torque adjustment mechanism. (5) A screw tightening status determination function that determines whether screw tightening is complete based on the current consumption value of the electric screwdriver 2. (6) A screw tightening diagnosis function that diagnoses whether the screw tightening operation was performed correctly based on the current consumption value of the electric screwdriver 2. (7) A driver stop function that stops the application of current to the electric screwdriver 2 in order to stop the driving of the electric screwdriver 2 (motor 21). (8) A setting function for setting screw tightening conditions, etc. based on setting signals received from an external device. Each function of the driver control unit 33 will be described below.

[0031] The driver driving function of the driver control unit 33 drives the electric screwdriver 2 by applying an applied current supplied from the power supply unit 31 to the electric screwdriver 2. The driver driving function can also appropriately change the magnitude of the applied current to the electric screwdriver 2, thereby limiting the torque of the electric screwdriver 2. In particular, in this embodiment, a user or administrator operates the setting unit 34 to store an upper limit of torque allowable in screw tightening work as a torque limit value Trl in the memory unit 32, and the driver driving function, in cooperation with a torque limiting function (described later), applies an applied current to the electric screwdriver 2 such that the torque of the electric screwdriver 2 is equal to or less than the torque limit value Trl, thereby limiting the torque of the electric screwdriver 2 to equal to or less than the torque limit value Trl.

[0032] The current consumption value acquisition function of the driver control unit 33 acquires the current consumption value from the electric screwdriver 2. The current consumption value of the electric screwdriver 2 acquired by the current consumption value acquisition function is the value of the current actually consumed by the motor 21 of the electric screwdriver 2, and even if the applied current applied by the driver drive function is constant, it will change depending on the influence of noise generated by the motor 21 of the electric screwdriver 2 and the screw tightening conditions. In this way, the current consumption value acquisition function acquires the current consumption value of the current actually consumed by the electric screwdriver 2, rather than the applied current value of the current applied to the electric screwdriver 2 from the driver control device 3, and thereby makes it possible to calculate the torque value of the electric screwdriver 2 with high accuracy using the torque conversion function, which will be described later.

[0033] The torque conversion function of the driver control unit 33 converts the current consumption value transmitted from the electric screwdriver 2 into the torque value of the electric screwdriver 2. In this embodiment, a correction value for converting the current consumption value of the electric screwdriver 2 into the torque value of the electric screwdriver 2 is pre-stored in the storage unit 32, and the torque conversion function converts the current consumption value of the electric screwdriver 2 into the torque value of the electric screwdriver 2 using this correction value.

[0034] It is known that the current consumption value of the electric screwdriver 2 and the torque value of the electric screwdriver 2 generally have a proportional relationship known as the IT characteristic. Therefore, in theory, the torque value can be calculated by multiplying the current consumption value by a certain coefficient corresponding to this proportional relationship. However, in practice, it has been found that an error of about 20% occurs between the torque of the electric screwdriver 2 measured by the torque sensor when the electric screwdriver is equipped with a torque sensor and a current sensor, and the torque calculated based on the IT characteristic from the current consumption value of the electric screwdriver 2 measured by the current sensor. This error is thought to be caused by voltage noise and current noise generated by the motor 21 and the screw tightening conditions.

[0035] Therefore, in this embodiment, a correction value for calculating the torque value of the electric screwdriver 2 for each current consumption value of the electric screwdriver 2 is stored in the storage unit 32, and the torque conversion function uses this correction value to calculate the torque value of the electric screwdriver 2 using the correction value corresponding to the current consumption value of the electric screwdriver 2. Note that the above correction value can be obtained by having the user or administrator perform normal screw tightening work in advance using the electric screwdriver 2 and a torque tester, sampling the current consumption value output by the electric screwdriver 2 and the torque value detected by the torque tester, and calculating the correction value for each current consumption value based on the sampled torque value and current consumption value of the electric screwdriver.

[0036] FIG. 3 is a graph showing an example of IT characteristics under a constant voltage. In the example shown in FIG. 3, it can be seen that when tightening a screw with a torque of 0.2 Nm, an applied current of approximately 2 A should be input to the motor 21. Therefore, the driver control unit 33 stores such an IT characteristics graph, and the driver drive function calculates an applied current value of 2 A as a reference current value to be applied to the electric screwdriver 2 when tightening a screw with a torque of 0.2 Nm. Furthermore, the driver drive function multiplies the reference current value by a correction value corresponding to the magnitude of the reference current value to calculate the applied current value actually applied to the electric screwdriver 2. Note that when a planetary gear with a gear ratio of 1 / 32 is used as the reducer 22, applying an applied current of 2 A and outputting a torque of 0.2 Nm allows tightening a screw with a torque of 0.2 Nm × 32 = 6.4 Nm.

[0037] Here, a specific method for calculating the correction value used in the torque conversion function will be described. In this embodiment, as described above, the electric screwdriver 2 used in the actual screw tightening operation is used in advance, and the conditions of the actual screw tightening operation (the type of screw and mounting material used in the actual screw tightening operation) are reproduced on a torque tester, and the screw is tightened. This allows sampling to be performed, in which the current consumption value of the electric screwdriver when tightening the screw is obtained from the electric screwdriver, while the torque value when tightening the screw is obtained from the torque tester. Then, a correction value for converting the current consumption value to a torque value for each current consumption value is calculated based on the relationship between the current consumption value and the torque value at the same time. Note that the calculation of the correction value may be performed by the driver control device 3, which obtains the torque value and the current consumption value from the torque tester and the electric screwdriver 2, respectively. Alternatively, an external device (such as a personal computer) may obtain the torque value and the current consumption value from the torque tester and the electric screwdriver 2, calculate the correction value, and then send it to the driver control device 3.

[0038] In this embodiment, in addition to calculating a correction value for each current consumption value, a correction value can also be calculated for each screw tightening condition. Even if the same electric screwdriver 2 is used, and the type of screw and mounting member are the same, the transmission efficiency at which the motor 21 converts current into torque may change due to aging and wear of the electric screwdriver 2. Therefore, it is preferable to periodically sample the current consumption value and torque value in accordance with maintenance, etc., calculate new correction values, and update the existing correction values ​​stored in the memory unit 32 with the newly calculated correction values. In this manner, using the latest correction values ​​allows for continuous, highly accurate calculation of torque values. In this embodiment, screw tightening conditions include, as described above, the type of screw, the type of mounting member, and the state of the electric screwdriver 2. However, other conditions may also be used as long as the torque value fluctuates relative to the current consumption value of the motor 21 of the electric screwdriver 2. By calculating a correction value for each screw tightening condition, the torque value can be calculated with high accuracy from the current consumption value of the motor 21 of the electric screwdriver 2.

[0039] The torque limiting function of the driver control unit 33 limits the torque of the electric screwdriver 2 by limiting the magnitude of the current applied to the electric screwdriver 2 by the driver drive function. For example, the required specifications for a screw tightening operation may specify that a screw be tightened at a predetermined torque value, such as 5 Nm. In this case, the torque limiting function can limit the torque value of the electric screwdriver 2 to 5 Nm so that the screw is not tightened at a torque value greater than the required torque value. Specifically, a torque limit value Trl is stored in the memory unit 32, and the torque limiting function limits the current applied to the electric screwdriver 2 so that the torque value calculated by the torque conversion function does not exceed the torque limit value Trl. More specifically, the torque control function compares the torque value calculated based on the current consumption value acquired from the electric screwdriver 2 with the torque limit value Trl. If the calculated torque value exceeds the torque limit value Trl, the driver stop function (described later) sends a drive stop signal from the driver control unit 3 to the electric screwdriver 2, causing the electric screwdriver 2 to stop driving the motor 21. The driver control device 3 can be configured to have a current limiting circuit, thereby executing a torque limiting function that limits the current so that the torque does not exceed a set torque value.

[0040] Furthermore, depending on the required specifications, a series of screw tightening work steps for tightening multiple screws may require that screws be tightened at multiple torque values. For example, a series of screw tightening work steps may be required in which five screws are tightened at 5 Nm, three screws are tightened at 1 Nm, and then ten screws are tightened at 3 Nm. To accommodate such requirements, the memory unit 32 can store multiple torque limit values ​​Trl corresponding to each task in the series of work steps, and the torque limit function can be configured to limit the torque of the screw tightening using the torque limit value Trl used for the current screw tightening task from among the multiple torque limit values ​​Trl. For example, by storing a plurality of torque limit values ​​Trl in advance in the memory unit 32 in the order of the screw tightening work steps, or by storing each torque limit value Trl in the memory unit 32 in association with each screw tightening work step, the torque limit function can be configured so that, in the above-mentioned series of screw tightening work steps, first, five screw tightening work steps are performed with the torque limit value Trl set to 5 Nm, then three screw tightening work steps are performed with the torque limit value Trl set to 1 Nm, and then ten screw tightening work steps are performed with the torque limit value Trl set to 3 Nm.

[0041] Next, the screw tightening state determination function of the driver control unit 33 will be described. The screw tightening state determination function determines whether the electric screwdriver 2 has completed screw tightening based on the current consumption value of the electric screwdriver 2. Specifically, the screw tightening state determination function determines whether the torque value calculated by the torque conversion function has reached the torque determination value Trt stored in the memory unit 32. The torque determination value Trt is a torque value at which it can be determined that screw tightening has been completed. A user or administrator can use the electric screwdriver 2 and a torque tester to sample the torque of the electric screwdriver in a normal screw tightening operation in chronological order in advance, and set the torque value at the timing when screw tightening is completed as the torque determination value Trt and store it in the memory unit 32.

[0042] The screw tightening state determination function determines that screw tightening is complete when the torque value calculated by the torque conversion function reaches the torque determination value Trt, and outputs to the notification unit 36 ​​or the display unit 35 a sound such as a buzzer, a light such as a flashing light, or text information that the torque value of the electric screwdriver 2 has reached the torque determination value (that screw tightening is complete), thereby notifying the user that screw tightening is complete.

[0043] Here, a method for setting the torque judgment value Trt will be described. Fig. 4 is a graph showing the relationship between the tightening state of a screw and the torque value and current consumption value of the electric screwdriver 2 during normal screw tightening work. In Fig. 4, the torque value and current consumption value of the electric screwdriver 2 are shown by the same line, assuming that they are proportional to each other. In Fig. 4, the upper part shows the tightening state of the screw, and the lower part shows an example of time-series data of the torque or current consumption value of the electric screwdriver 2 for each of the tightening states shown in the upper part.

[0044] In Figure 4, timing (a) shows the state immediately after a switch-on signal is output and screw tightening begins, and timing (b) shows the state in which the screw is rotated from the state shown in (a) and inserted into the screw hole. By driving motor 21 to rotate the screw from the state shown in (a), at timing (b) the screw is inserted into the hole while forming a groove on the side of the screw hole. In this case, the screw is not simply rotated, but a load is also applied to form the groove in the screw hole, so the torque and current consumption of electric screwdriver 2 increase, as shown in the graph at the bottom.

[0045] At the times shown in (c) and (d), the tip of the screw penetrates the screw hole, and no new grooves are formed in the screw hole. In this case, the screw is inserted along the already formed groove (no new grooves are formed), so the load required to tighten the screw is smaller than in the case shown in (b). As a result, the driver bit 26 rotates smoothly, and the torque and current consumption of the electric screwdriver 2 remain low, as shown in the graph at the bottom.

[0046] On the other hand, as shown in (e), when the seating surface of the screw head seats on the opening of the screw hole, the torque rises instantaneously due to collision between the screw head and the screw opening, and a peak (collision peak) of the torque and current consumption value appears. In this embodiment, as shown in (e) of Figure 4, the timing when the seating surface of the screw head seats on the opening of the screw hole and the collision between the screw head and the screw opening forms a collision peak of the torque value is set to the screw tightening completion timing, and the torque value of the electric screwdriver 2 at this screw tightening completion timing can be stored in the memory unit 32 as the torque judgment value Trt.

[0047] If the screw is further tightened, the torque and current consumption increase as the screw presses against the mounting member while being inserted. Then, at the timing shown in (f), when the rotational torque reaches a torque limit value Trl (described later) and the driving of the motor 21 stops, or when the female thread breaks and the screw starts to spin freely, the torque and current consumption of the electric screwdriver 2 drop sharply.

[0048] The screw tightening diagnosis function of the driver control unit 33 diagnoses abnormalities in the screw tightening operation of the electric screwdriver 2. Specifically, the screw tightening diagnosis function measures the screw tightening time from when screw tightening starts until the screw tightening state determination function determines that the screw tightening is complete, and if the measured screw tightening time is within a predetermined normal determination time period Tmt, it diagnoses that the screw tightening operation has been performed normally, and if it is outside the predetermined normal determination time period Tmt, it diagnoses that there has been an abnormality in the screw tightening operation.

[0049] FIG. 5 is a graph illustrating abnormality diagnosis of a screw tightening operation. In this embodiment, as shown in FIG. 5, a time period including the screw tightening time during normal screw tightening operation is stored in the memory unit 32 as the normal determination time period Tmt. The screw tightening time typically varies depending on screw tightening conditions such as the length of the screw and the material of the mounting member. However, if the screw tightening conditions are the same, normal screw tightening operation can be performed within a certain time range from the start of screw tightening to the completion of screw tightening. Therefore, in this embodiment, the screw tightening time during normal screw tightening operation is sampled for each screw tightening condition, and a certain range of time period including the time when the screw tightening is completed is set as the normal determination time period Tmt and stored in the memory unit 32. As described above, the normal determination time period Tmt can be set according to the screw tightening conditions, such as the type of screw, the type of mounting member, and the state of the electric screwdriver 2, in addition to the length of the screw and the material of the mounting member.

[0050] Specifically, a user or administrator can use a torque tester and the electric screwdriver 2 to sample the torque and current values ​​of the electric screwdriver 2 during normal screw tightening operations under each screw tightening condition. The user or administrator can then calculate the time (reference time Tms) from the time the starting current of the electric screwdriver 2 (motor) is detected to the time when the bearing surface of the screw head collides with the opening of the screw hole, resulting in a collision peak of the torque value of the electric screwdriver 2 (timing (f) in FIG. 4 ). The user or administrator can then store the time period including the reference time Tms as the normality determination time period Tmt in the memory unit 32. For example, if the time it takes to complete normal screw tightening (reference time Tms) is 1 second, the normality determination time period Tmt can be set as a time period from 0.5 seconds before and after the reference time Tms, ranging from 0.5 seconds to 1.5 seconds. The starting current of the electric screwdriver 2 (motor 21) generally peaks approximately 1 to 5 ms after the motor 21 starts operating. This current can be detected by measuring the current consumption value in the electric screwdriver 2 or by measuring the applied current value in the driver control device 3. Therefore, during sampling, the starting current of the motor 21 is detected by the current consumption value measuring unit 12 of the electric screwdriver 2, and when actually diagnosing screw tightening using the electric screwdriver 2, the starting current of the electric screwdriver 2 (motor 21) can also be detected in the driver control device 3.

[0051] In the example shown in FIG. 5, in the time-series data 1 of torque values ​​based on the current consumption value of the electric screwdriver 2, the time (A) from the start of the screw tightening operation to the detection of the collision peak falls within the normal judgment time period Tmt. In this case, the screw tightening diagnosis function can diagnose that the screw tightening operation was performed normally. On the other hand, in the example shown in FIG. 5, in the time-series data 2 of torque values ​​based on the current consumption value of the electric screwdriver 2, the time (B) until the screw tightening is completed falls earlier than the normal judgment time period Tmt. In this case, the screw tightening diagnosis function can diagnose that there is an abnormality, such as the screw diameter being too large compared to the diameter of the screw hole. Also, in the example shown in FIG. 5, in the time-series data 3 of torque values ​​based on the current consumption value of the electric screwdriver 2, the time (C) until the screw tightening is completed falls later than the normal judgment time period Tmt. In this case, the screw tightening diagnosis function can diagnose that there is an abnormality, such as the screw diameter being too small compared to the diameter of the screw hole, slippage of the screw, galling, or stripping of the screw head.

[0052] The screw tightening diagnosis function can also be configured to diagnose an abnormality such as the screw diameter being too small compared to the diameter of the screw hole, the screw spinning, galling, or stripped screw head if a certain time has passed without the torque of the electric screwdriver 2 reaching the torque judgment value Trt. This is because if the screw spins freely, the rotational torque may not increase and the torque may not reach the torque judgment value Trt. The certain time can be set for each screw tightening condition using the setting function. This is because the time it takes for the torque of the electric screwdriver 2 to reach the torque judgment value Trt during screw tightening work varies depending on the screw tightening conditions.

[0053] The driver stop function of the driver control unit 33 stops the drive of the electric screwdriver 2 by stopping the application of current to the electric screwdriver 2. In this embodiment, the driver stop function can be configured to stop the drive of the electric screwdriver 2 by sending a drive stop signal to the electric screwdriver 2 when the screw tightening state determination function determines that screw tightening is complete when the torque of the electric screwdriver 2 reaches a torque determination value Trt and / or when the torque value of the electric screwdriver 2 reaches a torque limit value Trl and is limited by the torque limit function. In particular, the driver stop function can protect the attachment member to which the screw is being attached by stopping the drive of the electric screwdriver 2 when the torque of the electric screwdriver 2 reaches the torque determination value Trt or the torque limit value Trl, even before a certain time has elapsed. Furthermore, the driver stop function can be configured to stop the drive of the electric screwdriver 2 when a certain time has elapsed, even before the torque of the electric screwdriver 2 reaches the torque determination value Trt or the torque limit value Trl. In this case, the attachment member can be protected.

[0054] The setting function of the driver control unit 33 can receive a setting signal from an external device such as a personal computer or a smartphone, and set a correction value, torque determination value Trt, torque limit value Trl, and / or normal determination time zone Tmt according to the screw tightening conditions based on the received setting signal. That is, in this embodiment, a user or administrator can use an external device to input the correction value, torque determination value Trt, torque limit value Trl, and / or normal determination time zone Tmt for each screw tightening condition, and by transmitting the correction value, torque determination value Trt, torque limit value Trl, and / or normal determination time zone Tmt input by the external device to the driver control unit 33, the setting function can store the correction value, torque determination value Trt, torque limit value Trl, and / or normal determination time zone Tmt in the memory unit 32.

[0055] The setting function also acquires information about screw tightening conditions input by a user or administrator via the setting unit 34, and stores a correction value, torque judgment value Trt, torque limit value Trl, and / or normal judgment time period Tmt corresponding to the screw tightening conditions in the storage unit 32. This allows the driver control unit 33 to perform torque conversion, judgment of the screw tightening state, torque limitation, screw tightening diagnosis, etc., using the set correction value, torque judgment value Trt, and torque limit value Trl. The driver control device 3 can exchange information with external devices by connecting to them via wire or wirelessly.

[0056] Furthermore, the setting function allows the user to operate the setting unit 34 of the driver control device 3 to set the screw tightening state determination function, the torque limiting function, and / or the screw tightening diagnosis function to ON / OFF.

[0057] Furthermore, in this embodiment, screws are actually tightened for each screw tightening condition, and the current consumption value and torque value of the electric screwdriver 2 during normal screw tightening work are sampled in chronological order for each screw tightening condition, so that the correction value, torque determination value Trt, and normal determination time period Tmt for each screw tightening condition can be stored in the storage unit 32. In this case, too, a user or administrator can use an external device to input the correction value, torque determination value Trt, and normal determination time period Tmt for each screw tightening condition to the driver control device 3, and the setting function can store the correction value, torque determination value Trt, and normal determination time period Tmt for each input screw tightening condition in the storage unit 32. Note that types of screws can be classified, for example, according to the thickness and length of the screw, and types of mounting members can be classified, for example, according to the material and hardness of the mounting member.

[0058] Furthermore, in this embodiment, the setting function can be configured to store multiple torque determination values ​​Trt and / or multiple torque limit values ​​Trl in the memory unit 32 according to a series of screw tightening work steps for tightening multiple screws, and the driver control unit 33 can be configured to determine the screw tightening state and limit the torque using the torque determination value Trt and / or the torque limit value Trl corresponding to each screw tightening work in the series of screw tightening work steps. For example, if a user needs to repeat a series of screw tightening work steps in which five screws are tightened with 5 Nm, three screws are tightened with 1 Nm, and then ten screws are tightened with 3 Nm, the driver control unit 33 can determine whether the user first tightens five screws with the torque determination value Trt set to 5 Nm and the torque limit value Trl set to 5+αNm, then tightens three screws with the torque determination value Trt set to 1 Nm and the torque limit value Trl set to 1+αNm, and then tightens ten screws with the torque determination value Trt set to 3 Nm and the torque limit value Trl set to 3+αNm.

[0059] This allows a series of screw tightening steps to be performed with a single electric screwdriver 2, something that could not be achieved with conventional electric screwdrivers. Conventionally, to tighten screws with an electric screwdriver at a constant torque value, an electric screwdriver is provided with a clutch mechanism that mechanically cuts off torque transmission when the torque of the electric screwdriver reaches a certain torque value. However, the torque value for cutting off torque transmission can be adjusted by adjusting the expansion and contraction of the spring in the clutch mechanism. Therefore, for example, if a series of work steps is repeated in which five screws are tightened at 5 Nm, three screws are tightened at 1 Nm, and then ten screws are tightened at 3 Nm, it is necessary to either adjust the expansion of the spring to change the torque cutoff value each time the torque value for tightening the screws changes, or to prepare and use three electric screwdrivers with different torque cutoff values. In contrast to this, in this embodiment, the driver control unit 33 can freely change the torque judgment value Trt and the torque limit value Trl, so torque control can be easily performed without using a conventional clutch mechanism, and as a result, it is possible to perform screw tightening work in succession according to various torques with a single electric screwdriver 2.

[0060] Here, a more specific example of a series of screw tightening operations will be described. In this embodiment, the setting function can set 12 types of screw tightening operations in the memory unit 32, for example: (1) 300 ms with a torque of 5 Nm, (2) 600 ms with a torque of 3 Nm, (3) 200 ms with a torque of 10 Nm, (4) 800 ms with a torque of 1 Nm, (5) 400 ms with a torque of 2 Nm, (6) 500 ms with a torque of 4 Nm, (7) 300 ms with a torque of 6 Nm, (8) 500 ms with a torque of 7 Nm, (9) 300 ms with a torque of 9 Nm, (10) 400 ms with a torque of 11 Nm, (11) 200 ms with a torque of 10 Nm, and (12) 500 ms with a torque of 12 Nm. Furthermore, in this case, the setting function can set a registration example 1 of a series of screw tightening operations to repeatedly tighten screws in the order of the above conditions (3), (10), and (4); a registration example 2 of a series of screw tightening operations to repeatedly tighten screws in the order of the above conditions (5), (8), and (2); and a registration example 3 of a series of screw tightening operations to repeatedly tighten screws in the order of the above conditions (9), (3), and (6).

[0061] By setting screw tightening conditions in advance, such as the screw tightening conditions (1) to (12) above, and setting combinations of these conditions as screw tightening conditions for a series of screw tightening tasks, the driver control unit 33 can perform multiple screw tightening operations with a single electric screwdriver 2, reducing the number of electric screwdrivers required for a series of screw tightening tasks. Furthermore, since a series of screw tightening tasks can be set by combining pre-registered screw tightening conditions, the work scene setting (setting of a series of screw tightening tasks) itself can be simplified. Such settings can be set by the worker operating the setting unit 34, or by receiving an external signal from an external device (e.g., a personal computer). Furthermore, by displaying the details of the screw tightening conditions for the series of screw tightening tasks that have been set on the display unit 35 of the driver control device 3, the worker and manager can understand the details of the screw tightening tasks to be performed by the electric screwdriver 2.

[0062] In this embodiment, the user can select, by operating the setting unit 34, a mode in which the torque value determined by sampling at the timing when screw tightening is completed is used as the torque judgment value Trt, or a mode in which multiple torque values ​​required by specifications are used as the torque judgment value, and the setting function can be configured to set the torque judgment value Trt according to the selected mode. Also, the setting function can be configured to set a predetermined torque Nm as the torque judgment value Trt to determine whether the screw tightening operation was performed with a predetermined torque (Nm).

[0063] Furthermore, the setting function can be configured to automatically store the current consumption value and torque value sampled by the user or administrator, and can also be configured to automatically set the correction value, torque determination value Trt, and / or normal determination time period Tmt from the sampled current consumption value and torque value data.

[0064] As described above, in the electric screwdriver system 1 according to this embodiment, the driver control device 3 repeatedly acquires the current consumption value of the electric screwdriver 2 in chronological order and determines the state of screw tightening by the electric screwdriver 2 based on the acquired current consumption value. Specifically, the driver control device 3 stores a correction value for converting the current consumption value into a torque value, which is set based on the sampled current consumption value of the electric screwdriver 2 during normal screw tightening work, and stores a torque value for determining whether screw tightening is complete, which is set based on the sampled torque value, as a torque determination value Trt. The driver control device 3 then acquires the current consumption value of the electric screwdriver 2 detected by the electric screwdriver 2, multiplies the calculated torque value by a correction value corresponding to the current consumption value, and determines that screw tightening is complete when the calculated torque value reaches the pre-stored torque determination value Trt. As described above, in the electric screwdriver system 1 according to this embodiment, the electric screwdriver 2 does not need to have a torque sensor, allowing the electric screwdriver 2 to have a simple configuration. Furthermore, since the driver control device 3 can be configured simply by changing the program, without requiring any changes to the existing configuration, the electric screwdriver system 1 can be provided at low cost.

[0065] Furthermore, in this embodiment, a normal screw tightening operation is actually reproduced, and time-series data of the current consumption value and torque value of the electric screwdriver 2 during normal screw tightening operation is sampled. This makes it possible to identify the relationship between the current consumption value and the torque value in a noisy environment. This makes it possible to appropriately calculate the torque value of the electric screwdriver 2 based on the current consumption value of the electric screwdriver 2, even in a noisy environment. In particular, in this embodiment, the current actually consumed by the motor 21 of the electric screwdriver 2 is measured as the current consumption value, and the torque value is calculated based on the current consumption value transmitted from the electric screwdriver 2 to the driver control device 3. This makes it possible to calculate the torque value of the electric screwdriver 2 with higher accuracy than when the torque value is calculated based on the applied current applied to the electric screwdriver 2 by the driver control device 3. As a result, even when there is a discrepancy between the applied current value of the current applied to the electric screwdriver 2 by the driver control device 3 and the amount of current actually consumed by the motor 21 of the electric screwdriver 2 due to noise or screw tightening conditions, it becomes possible to appropriately determine whether the torque of the electric screwdriver 2 has reached the torque determination value Trt.

[0066] Furthermore, in this embodiment, the screw tightening conditions include not only the type of screw (screw diameter, screw length, screw material, etc.) and the type of mounting member to which the screw is attached (diameter of the hole drilled in the mounting member, material of the mounting member, etc.), but also the state of the electric screwdriver 2 (model of the electric screwdriver 2, type of motor 21 of the electric screwdriver 2, deterioration over time of the electric screwdriver 2, wear of each component of the electric screwdriver 2, etc.), and a correction value is set for each screw tightening condition. In particular, by setting a correction value according to the deterioration over time of the electric screwdriver 2 and the wear of each component of the electric screwdriver 2, it is possible to properly calculate torque based on the current consumption even when the electric screwdriver 2 has deteriorated over time or worn out, reducing the efficiency of transmission of current to torque in the motor 21.

[0067] Furthermore, in the electric screwdriver system 1 according to this embodiment, for example, when a series of work steps is repeated, such as tightening five screws at 5 Nm, tightening three screws at 1 Nm, and then tightening ten screws at 3 Nm, the program sets the respective target torque values ​​(5 Nm, 1 Nm, 3 Nm) as first to third torque judgment values. The program then determines whether the torque value based on the current consumption value of the electric screwdriver 2 reaches these torque judgment values, thereby determining whether each torque value in the series of work steps meets the required specifications. In particular, in conventional electric screwdrivers, the upper limit of torque output is set by adjusting the extension of the spring 27. Therefore, if the torque value required for screw tightening changes as described above, it is necessary to use three electric screwdrivers with different torques or adjust the extension of the spring 27 according to the change in the specified torque for screw tightening. In contrast, in this embodiment, by setting multiple torque judgment values ​​in the driver control device 3, the driver control unit 33 can determine whether the torque value meets the required specifications based on the current consumption value of the electric screwdriver 2, without changing the electric screwdriver 2.

[0068] Although the preferred embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the above-described embodiments. Various modifications and improvements can be made to the above-described embodiments, and such modifications and improvements are also included in the technical scope of the present invention.

[0069] For example, in the above-described embodiment, a configuration was exemplified in which the driver control device 3 determines the screw tightening state by comparing the torque judgment value Trt stored in the memory unit 32 with the torque value calculated based on the current consumption value of the electric screwdriver 2, but this configuration is not limited to this. The memory unit 32 can store the current consumption value when screw tightening is completed successfully from the sampling data as a current judgment value, and determine the screw tightening state by comparing the current judgment value with the current consumption value obtained from the electric screwdriver 2.

[0070] Furthermore, in the above-described embodiment, the electric screwdriver system 1 includes the electric screwdriver 2 and the driver control device 3. However, the present invention is not limited to this configuration. As shown in FIG. 6, the driver control device 3 can be integrated into the housing 30 of the electric screwdriver 2. FIG. 6 is a configuration diagram showing an electric screwdriver system 1a according to another embodiment. In addition to the configuration of the electric screwdriver system 1 described above, the electric screwdriver system 1a shown in FIG. 6 also includes a forward / reverse rotation control switch 41 and a battery 42. The forward / reverse rotation control switch 41 is operated by an operator and can change the rotation direction of the motor 21. The battery 42 is a rechargeable secondary battery that supplies power to the motor 21 via the driver control unit 33. This configuration allows the electric screwdriver 2 to be portable and operable without being plugged into a commercial power source. This allows the electric screwdriver system 1 to be provided inexpensively as a tool for DIY projects or carpentry, for example.

[0071] FIG. 7 is a diagram showing the setting unit 34, display unit 35, and notification unit 36 ​​of the electric screwdriver system 1a shown in FIG. 6. By operating the setting unit 34, the operator can numerically input the torque value to be used when tightening a screw, and the driver control unit 33 can tighten the screw at the set torque value. Furthermore, the display unit 35 can display the torque value at the completion of screw tightening when the screw tightening is complete. In this way, like the electric screwdriver system 1, the electric screwdriver system 1a shown in FIG. 6 can also control the screw tightening operation without using a torque setting mechanism of a conventional electric screwdriver (a cam mechanism using a torque adjustment spring for tightening setting) or a torque monitoring mechanism using a torque sensor.

[0072] Furthermore, in the electric screwdriver system 1a shown in FIG. 6, the driver control unit 33 can also change the number of rotations during screw tightening by controlling the voltage. For example, in the past, even if an 8 mm long screw was tightened for 10 mm, causing a collision between the mounting part and the screw and breaking the mounting part or the screw, it may have been determined to be a normal operation if the abnormality was determined based solely on the torque during the screw tightening operation. In contrast, in this embodiment, by monitoring the screw tightening length (number of rotations), the electric screwdriver can be stopped at a length of 8 mm, preventing the screw from colliding with the mounting part. Furthermore, if the tightening length of the screw is longer than the screw length, it is determined to be an NG operation, and the operation of the electric screwdriver can be stopped and the operator can be notified by the notification unit 36 ​​(for example, an NG buzzer or NG lamp).

[0073] Additionally, in the above-described embodiment, the electric screwdriver 2 is driven using power supplied from the driver control device 3, but the electric screwdriver 2 may have a battery, as in small electric screwdrivers used in medical or dental treatment. In this case, the driver control device 3 may also acquire a current consumption value from the electric screwdriver 2, and control the value of the current applied to the electric screwdriver 2 based on a torque value calculated based on the acquired current consumption value.

[0074] Furthermore, in the above-described embodiment, the driver control device 3 is configured to send a drive stop signal to stop the drive of the electric screwdriver 2 when the torque value calculated based on the current consumption value of the electric screwdriver 2 reaches the torque limit value Trl, but this configuration is not limited to this, and the configuration can also be such that when the torque value reaches the torque limit value Trl, the current applied from the driver control device 3 to the electric screwdriver 2 is limited so that the torque value does not exceed the torque limit value Trl, and the drive of the electric screwdriver 2 is not stopped.

[0075] In addition, in the above-described embodiment, a configuration has been exemplified in which the memory unit 32 stores a torque judgment value Trt for determining whether screw tightening has been completed and a normal judgment time period Tmt for diagnosing whether screw tightening has been performed normally, but this configuration is not limited to this. The memory unit 32 may also be configured to store time series data of the current consumption value of the electric screwdriver 2 during normal screw tightening work, and the driver control unit 33 may calculate the torque judgment value Trt and the normal judgment time period Tmt based on the time series data of the current consumption value obtained from the memory unit 32.

[0076] In addition, in the above-described embodiment, a configuration was exemplified in which the driver control device 3 has a current limiting circuit, and the driver drive function limits the magnitude of the current applied to the electric driver 2, thereby limiting the torque of the electric driver 2. However, this configuration is not limited to this, and a configuration may also be adopted in which the electric driver 2 has a current limiting circuit that limits the current applied to the motor 21, and by limiting the current in the electric driver 2, the torque of the electric driver 2 is prevented from exceeding the torque limit value.

[0077] Furthermore, in the above-described embodiment, the driver control device 3 is configured to issue a notification via the notification unit 36 ​​when it determines that screw tightening is complete, but this is not limiting, and the determination result of the screw tightening state can also be output to an external device. Also, the driver control device 3 can be configured to output data on the correction value and the torque determination value Trt and / or torque limit value Trl set by the user or administrator to an external device. Furthermore, the driver control device 3 can be configured to output time-series data on the current consumption value or torque value of the electric screwdriver 2 during screw tightening work, and the work history of the screw tightening work (such as a history of how many times the screw tightening work was performed at how many Nm) to an external device.

[0078] In addition, in the above-described embodiment, a configuration has been exemplified in which a correction value is calculated based on the current consumption value obtained from the electric screwdriver 2 and the torque value obtained from the torque tester when a screw tightening operation is actually performed using the electric screwdriver 2 and a torque tester, but this configuration is not limited to this, and a configuration may also be used in which a sampling electric screwdriver equipped with a torque sensor is used, and the current consumption value and torque value are obtained from this setting electric screwdriver to calculate the correction value. In this case, it is preferable to use an electric screwdriver for sampling that matches the model, motor type, age of use, etc. of the electric screwdriver 2 that will actually be used. [Explanation of symbols]

[0079] 1,1a...Electric driver system 2...Electric screwdriver 10...Control unit 11...Motor drive control unit 12...Current consumption measurement unit 13...Lever switch 14...Press switch 20...Drive unit 21...Motor 22...Reducer 24...Bit Folder 25…Chuck 26...Driver bit 27...Spring 28...Lever gear 29...Torque clutch limit switch 30…Case 3...Driver control device 32...Storage section 33...Driver control unit 34...Settings section 35...Display section 36…Information Department 37...Power supply section 41...Forward / reverse control switch 42...Battery 4...Power cord 5...Signal code

Claims

1. An electric screwdriver system having an electric screwdriver and a driver control device that controls the operation of the electric screwdriver, The electric screwdriver is A motor and a current consumption value detection means for detecting a current value of the motor as a current consumption value; a transmitting means for transmitting the current consumption value to the driver control device, The driver control device a current value acquiring means for acquiring the current consumption value transmitted from the electric screwdriver by the transmitting means; a screw tightening state determination means for determining a state of screw tightening by the electric screwdriver based on the consumed current value acquired by the current value acquisition means; an output means for notifying or externally outputting the result of the determination by the screw fastening state determination means; a storage means for storing a correction value for converting the current consumption value into the torque value, the correction value being set based on the current consumption value and torque value of the electric screwdriver sampled during normal screw tightening work, and for storing a torque value for determining that screw tightening is complete, the torque value being set based on the sampled torque value, as a determination value; The screw tightening state determination means determines the screw tightening state by comparing a torque value calculated based on the current consumption value acquired by the current value acquisition means and the correction value with the determination value stored in the memory means.

2. the correction value is not a uniform value but a value set for each current consumption value based on the sampled current consumption value and torque value of the electric screwdriver, the storage means stores the correction value for each of the current consumption values; 2. The electric screwdriver system according to claim 1, wherein the screw tightening state determining means converts the current consumption value into the torque value using the correction value corresponding to the current consumption value.

3. An electric screwdriver system having an electric screwdriver and a driver control device that controls the operation of the electric screwdriver, The electric screwdriver is A motor and a current consumption value detection means for detecting a current value of the motor as a current consumption value; a transmitting means for transmitting the current consumption value to the driver control device, The driver control device a current value acquiring means for repeatedly acquiring the current consumption value transmitted from the electric screwdriver by the transmitting means in a time series manner; a screw tightening state determination means for determining a state of screw tightening by the electric screwdriver based on the consumed current value acquired by the current value acquisition means; an output means for notifying or externally outputting the result of the determination by the screw fastening state determination means; and a storage means for storing a current consumption value for determining that screw tightening is complete as a determination value, the current consumption value being set based on the current consumption value of the electric screwdriver sampled during normal screw tightening work, The screw tightening state determination means determines the screw tightening state by comparing the current consumption value acquired by the current value acquisition means with the determination value stored in the storage means.

4. When two or more torque values ​​are required in a series of work steps for tightening a plurality of screws, the storage means stores two or more judgment values ​​corresponding to the two or more required torque values ​​for each work step in the series of work steps, 2. The electric screwdriver system according to claim 1, wherein the screw tightening state determination means converts a current consumption value of the electric screwdriver into the torque value, and determines the screw tightening state by comparing the converted torque value with the determination value for each task in the series of work processes.

5. the storage means has a function of updating the correction value when the sampling is newly performed, The electric screwdriver system according to claim 1 , wherein when the correction value is updated, the screw tightening state determination means converts the torque value using the updated correction value to determine the screw tightening state.

6. the storage means stores the judgment value for each screw tightening condition based on the current consumption value and / or torque value of the electric screwdriver sampled for each screw tightening condition consisting of a combination of at least the type of screw and / or the type of mounting member to which the screw is attached, The electric screwdriver system according to claim 1 or 3, wherein the screw tightening state determination means acquires information on the screw tightening conditions for which the screw is to be tightened, and determines the screw tightening state using the determination value corresponding to the acquired screw tightening conditions.

7. the storage means stores, in the sampling, a time period including a time from when the screw tightening starts until a peak in the torque value or the current consumption value is formed as a result of the bearing surface of the screw hitting the opening of the screw hole, as a normal determination time period; The electric screwdriver system according to claim 1 or 3, wherein the screw tightening state determination means calculates the time from when the screw tightening starts until a peak in the current consumption value or torque value is formed due to the screw seat colliding with the opening of the screw hole, based on the current consumption value of the electric screwdriver, and determines that there is an abnormality in the screw tightening operation if the calculated time falls outside the normal determination time period.

8. A driver control device electrically connected to an electric driver having a motor and detecting a current value of the motor as a current consumption value, and controlling the operation of the electric driver, a current value acquiring means for repeatedly acquiring a current consumption value of the electric screwdriver in chronological order from the electric screwdriver; a screw tightening state determination means for determining a state of screw tightening by the electric screwdriver based on the consumed current value acquired by the current value acquisition means; an output means for notifying or externally outputting the result of the determination by the screw fastening state determination means; a storage means for storing a correction value for converting the current consumption value into the torque value, the correction value being set based on the current consumption value and torque value of the electric screwdriver sampled during normal screw tightening work, and for storing a torque value for determining that screw tightening is complete, the torque value being set based on the sampled torque value, as a determination value; The screw tightening state determination means determines the screw tightening state by comparing a torque value calculated based on the current consumption value acquired by the current value acquisition means and the correction value with the determination value stored in the memory means.

9. A driver control device electrically connected to an electric driver having a motor and detecting a current value of the motor as a current consumption value, and controlling the operation of the electric driver, a current value acquiring means for repeatedly acquiring a current consumption value of the electric screwdriver in chronological order from the electric screwdriver; a screw tightening state determination means for determining a state of screw tightening by the electric screwdriver based on the consumed current value acquired by the current value acquisition means; an output means for notifying or externally outputting the result of the determination by the screw fastening state determination means; a storage means for storing a current consumption value for determining that screw tightening is complete as a determination value, the current consumption value being set based on the sampled current consumption value of the electric screwdriver during normal screw tightening work; The screw fastening state determination means determines the screw fastening state by comparing the current consumption value acquired by the current value acquisition means with the determination value stored in the storage means.

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