Methods and apparatus for computer-controlled monitoring of bolt tightening processes using a tightening system.

Abstract

A method for computer-implemented supervision of a bolt tightening (100) process using a tightening system, the tightening system comprising: a manually operated tightening tool (10) including an actuator (11) for rotating the bolt, the manually operated tightening tool (10) being configured to switch between a first operating mode and a second operating mode, wherein in the first operating mode the actuator (11) of the tightening tool (10) can operate according to at least one tightening sequence, and in the second operating mode the actuator (11) of the tightening tool (10) can operate according to a loosening sequence, each tightening sequence and loosening sequence including predetermined operating parameters for the actuator (11) of the tightening tool (10), and the tightening tool (10) further comprising a sensor unit (12) for determining at least one parameter (P1, P2) of the bolt connection during and / or after the completion of the tightening sequence, wherein each of the at least one parameter (P1, P2) represents a quality metric of the bolt connection; wherein the tightening system further comprises: a processing unit (20) for processing data from the sensor unit. The method includes the following steps: receiving at least one parameter (P1, P2) from the tightening tool (10) via the interface (21) in a first operating mode, during and / or after the completion of a tightening sequence; determining the state (ST) of the bolt connection based on at least one parameter (P1, P2), wherein the state (ST) includes a first state indicating a correct bolt connection and a second state indicating a faulty bolt connection; and a user interface (30) for outputting connection information about the bolt connection; the method includes the following steps: receiving at least one parameter (P1, P2) of the bolt connection from the tightening tool (10) via the interface (21) in a first operating mode; determining the state (ST) of the bolt connection when and / or after the completion of the bolt connection; switching the actuator (11) of the tightening tool (10) from the first operating mode to the second operating mode if the state (ST) corresponds to the second state; and switching the tightening tool (10) from the second operating mode to the first tightening sequence in at least one tightening sequence of the first operating mode to re-tighten the bolt (51, 52, 53).

Description

Technical Field

[0001] This invention relates to a method and apparatus for computer-controlled monitoring of the bolt tightening process using a tightening system. Background Technology

[0002] In large factory structures, components such as wind turbines are connected using bolts. Bolts are a key indicator of quality because they must withstand harsh conditions for over 25 years. If a bolt connection fails, the entire structure can collapse. Therefore, quality control of the bolt tightening process is crucial. For archiving purposes, each step of the bolt tightening process must be monitored and stored in a monitoring system.

[0003] Currently, information regarding tightening procedures must be manually verified by workers. Information regarding technical parameters must be verified across different software systems, which is time-consuming and only allows for manual quality control afterwards.

[0004] Existing software tools exist for monitoring the bolt tightening process and are used in the automotive industry. They guide workers through the tightening process. Sometimes, such software tools are combined with positioning systems, which check whether workers are performing process steps in the correct positions. Assembly line production ensures that products always arrive at the same point in the workstation. Therefore, it is easy to predefine the position of the bolts on the product, making it easy to integrate positioning systems for quality control.

[0005] Due to the different working environment, these existing software tools cannot be used in large factory structures. In large factory structures, products or workpieces are moved or hoisted from one workstation to another, meaning that products or workpieces are not always in the same location within the workstation. After a product enters a workstation, many workers spend long periods of time working around the product, making it difficult to utilize existing software tools from the automotive industry. Summary of the Invention

[0006] The purpose of this invention is to provide a simple method for monitoring the tightening process of bolts using a tightening system.

[0007] The independent claims of this patent address this problem. The dependent claims define preferred embodiments of the invention.

[0008] This invention provides a method for computer-controlled supervision of the bolt tightening process using a tightening system.

[0009] The tightening system includes a manually operated tightening tool comprising an actuator for rotating the bolt. The manually operated tightening tool is configured to switch between a first operating mode and a second operating mode. In the first operating mode, the actuator of the tightening tool can operate according to at least one tightening sequence, and in the second operating mode, the actuator of the tightening tool can operate according to a loosening sequence. Each of the tightening and loosening sequences includes predetermined operating parameters for the actuator of the tightening tool. Furthermore, the tightening tool has a sensor unit for determining at least one parameter of the bolted connection during and / or after the completion of the tightening sequence. Each of the at least one parameter represents a quality measure of the bolted connection.

[0010] Furthermore, the tightening system includes a processing unit for processing at least one parameter received from the sensor unit, wherein the processing unit is configured to determine the state of the bolt connection based on the at least one parameter, wherein the state includes a first state indicating a correct bolt connection and a second state indicating a faulty bolt connection.

[0011] In addition, the tightening system includes a user interface for outputting connection information about the bolt connection. This output connection information can be used to guide the worker through the tightening process or to provide feedback to the worker.

[0012] According to the method of the present invention, the following steps are performed during the operation of the tightening system.

[0013] In step a), in the first operating mode, during and / or after the completion of the tightening sequence, at least one parameter of the bolt connection is received from the tightening tool via an interface.

[0014] In step b), the state of the bolted connection is determined when and / or after the bolted connection is completed.

[0015] In step c), if the state of the bolted connection corresponds to the second state, i.e., indicating a faulty bolted connection, the actuator of the tightening tool is switched from the first operating mode to the second operating mode.

[0016] In step d), the tightening tool is switched from the second operating mode to the first tightening sequence in at least one tightening sequence of the first operating mode to retighten the bolt.

[0017] The method of this invention provides a simple and direct way to automatically monitor the bolt tightening process using a tightening system. Specifically, the operator of the tightening tool does not need to manually input any information into the software tool used for quality monitoring. Furthermore, in the case of a faulty bolt connection, there is no need to manually switch the operating mode of the tightening tool. When the processing unit determines that a bolt connection is faulty, the faulty bolt connection can be loosened automatically without manually switching the tightening tool. After loosening the faulty bolt connection, the operating mode of the tightening tool is switched again to allow for retightening of the bolt without manual switching. As another advantage, in cases where multiple tightening sequences are required to tighten the bolts, it ensures that retightening begins with the first tightening sequence.

[0018] According to another preferred embodiment, the method includes a further step e): controlling the actuator of the tightening tool from the first tightening sequence to at least one subsequent tightening sequence of the first operating mode to retighten the bolt according to a predetermined order of the tightening sequence. According to this embodiment, it can be ensured that the worker operating the tightening tool will perform the full number of tightening sequences, regardless of which of the multiple tightening sequences is erroneous.

[0019] According to another preferred embodiment, the step of switching the tightening tool from the first operating mode to the second operating mode and / or switching the tightening tool from the second operating mode to the first operating mode in a first tightening sequence or a subsequent tightening sequence is performed under the automatic control of the processing unit. Therefore, the worker does not need to perform any manual steps to control the tightening tool.

[0020] According to another preferred embodiment, the user interface outputs the status of the bolted connection and / or at least one parameter representing a quality metric of the bolted connection as connection information on a display. Displaying the connection information on the display allows the operator of the tightening equipment to confirm whether the bolted connection is correct (OK) or faulty (NOK). This is further preferred if the connection information is output in real time.

[0021] According to another preferred embodiment, step d is initiated after the following steps have been performed: In step c1), in a second operating mode, during and / or after the completion of the loosening sequence, at least one parameter of the bolted connection is received from the tightening tool. In step c2), it is determined whether the bolted connection is completely loosened. Therefore, it can be ensured that the bolted connection is completely loosened before retightening the bolts in a predetermined number of tightening sequences begins.

[0022] The status of the connection information is updated each time a worker works on the bolt. Therefore, it is preferable that the user interface immediately prevents the display of the bolt connection after step c2) is completed.

[0023] According to another preferred embodiment, the tightening system further includes a positioning unit configured to determine the position of the tightening tool relative to a reference point of the product or workpiece to be bolted during the tightening or loosening process of the bolt. The processing unit is configured to perform the following steps: in step e1), determining the position of the tightening tool during the tightening process of the bolt; in step e2), storing the position of the tightening tool as a first position if the state of the bolt connection corresponds to the second state; and in step e3), releasing the tightening tool to loosen the bolt associated with the second state only if the current position of the tightening tool corresponds to the first position. Therefore, two positions of the tightening tool are compared, wherein the first position corresponds to the working position of the bolt marked as faulty, and the second position of the tightening tool corresponds to the working position of the bolt to be loosened. If the two positions match, the tightening tool is released (i.e., its actuator can be controlled to start rotating), and the loosening process can begin. If the positions do not match, the tightening tool is not released. Therefore, the worker cannot control the tightening tool to turn its actuator. Consequently, the worker receives instant tactile feedback on whether he is working on the correct bolt. This allows errors to be minimized or even avoided.

[0024] According to another preferred embodiment, if the state of the bolted connection corresponds to the second state, a counter associated with the corresponding bolted connection is incremented by 1. This counter starts from a predetermined initial value if the bolted connection's state first corresponds to the second state, and starts from the last stored value if the bolted connection's state subsequently corresponds to the second state every time. Preferably, if the actual value of the counter exceeds a predetermined threshold, an instruction to use a new bolt is output on the user interface. This particular embodiment can be combined with a storage system built using KANBAN logic, which enables monitoring to ensure that the worker has actually removed the new bolt.

[0025] In addition to the methods described above, the present invention also relates to an apparatus for computer-implemented supervision of the bolt tightening process using a tightening system, wherein the apparatus is configured to perform the method according to the invention or one or more preferred embodiments thereof.

[0026] Furthermore, the present invention relates to a computer program product having program code stored on a non-transitory machine-readable medium for performing the method according to the invention or one or more preferred embodiments thereof when the program code is executed on a computer.

[0027] Furthermore, the present invention relates to a computer program having program code for performing the method according to the invention or one or more preferred embodiments thereof when the program code is executed on a computer. Attached Figure Description

[0028] Embodiments of the invention will now be described in detail with reference to the accompanying drawings.

[0029] Figure 1 A schematic diagram of a tightening system according to the present invention for computer-implemented supervision of the bolt tightening process is shown.

[0030] Figure 2 The flowcharts illustrating different steps of the method according to the present invention are shown based on a basic embodiment.

[0031] Figures 3 to 11 The diagrams show workpieces to be bolted together using three bolts, and a display screen on the user interface indicating the process of a worker operating a tightening tool according to the tightening system of the present invention to bolt together the workpieces. Detailed Implementation

[0032] Figure 1 A schematic diagram of a tightening system 100 according to the invention for computer-controlled supervision of the bolt tightening process is shown. By way of example only, the tightening system 100 is used to tighten three bolts 51, 52, and 53 of a workpiece 50 (e.g., a wind turbine). However, the workpiece 50 can be any product of a large factory construction to be mounted onto another product.

[0033] The tightening system 100 includes a manually operated tightening tool 10, a processing unit 20, and a user interface 30. The tightening system 100 may also optionally include a positioning unit 40.

[0034] The tightening tool 10 includes an actuator 11, a sensor unit 12, and a processor 13. The actuator 11 may be a motor connected to a tool holder for subsequently rotating bolts 51, 52, and 53. The tightening tool 10 is configured to switch between a first operating mode and a second operating mode. Switching between the first and second operating modes is performed under the control of the processor 13. In the first operating mode, the actuator 11 rotates in a first rotational direction (forward direction) to tighten bolts 51, 52, and 53. In the second operating mode, the actuator rotates in a second rotational direction (reverse direction) opposite to the first rotational direction to loosen bolts 51, 52, and 53.

[0035] In the first operating mode, the actuator 11 of the tightening tool 10 can operate according to one or more tightening sequences. The corresponding tightening sequence includes predetermined control parameters for the actuator 11 of the tightening tool 10, such as rotational speed and / or torque, to achieve one or more predetermined parameters of the bolted connection, such as torque and / or angle, during and / or after the tightening process. These predetermined parameters P1, P2 represent quality measures of the bolted connection (see below). Figures 3 to 11 (The display screen in the middle).

[0036] If bolts 51, 52, and 53 must be tightened in multiple sequences, the tightening process is performed in multiple steps. For example, in the first step, bolts 51, 52, and 53 are tightened up to 75% of the final torque. After completing the first step, bolts 51, 52, and 53 must be allowed to settle. After a short rest, the tightening process is completed by tightening the final 25% to achieve the final torque.

[0037] In the second operating mode, the actuator 11 of the tightening tool 10 can operate in a loosening sequence. In the loosening sequence, the actuator 11 of the tightening tool 10 is controlled to rotate in a second rotation direction to completely loosen bolts 51, 52, and 53.

[0038] Sensor unit 12 includes one or more sensors, such as torque sensors and / or speed sensors and / or force sensors. Sensor unit 12 is adapted to determine one or more parameters P1, P2 of the bolted connection during and / or after the completion of the tightening and loosening sequences, respectively.

[0039] The processing unit 20 includes a first interface 21, a second interface 22, an optional third interface 23, and a processor 24.

[0040] The processing unit 20 is connected to the tightening tool 10 via the first interface 21 to provide corresponding control data to switch the tightening tool 10 between the first operating mode and the second operating mode, and to apply the correct control data for the corresponding tightening sequence in the first operating mode.

[0041] Furthermore, the processing unit 20 receives one or more parameters P1, P2 acquired by the sensor unit 12 via the first interface 21, in order to determine the state ST of each bolt connection based on one or more parameters of the sensor unit 12 (see...). Figures 3 to 11 (The display screen in the middle). The status ST of the bolted connection includes a first status (“OK”) indicating a correct bolted connection and a second status (“NOK”) indicating a faulty bolted connection.

[0042] User interface 30 includes a display 31 and an input device 32. The display 31 and input device 32 can be combined into a single user interface (such as a touchscreen). Display 31 displays information about the bolt connection, such as one or more parameters P1, P2, the success or failure of the bolt connection (i.e., status "OK" or status "NOK"), etc. The information output via display 31 can guide the worker during the tightening of multiple bolts 51, 52, 53. (This will be mentioned later.) Figures 3 to 11 The illustration shows an example of such a display screen.

[0043] User interface 30 is connected to processing unit 20 via second interface 22. The information to be displayed on display 31 is determined by processor 24 of processing unit 20 based on sensor data received from tightening tool 10 and optionally output via second interface 22.

[0044] The positioning unit 40 includes a sensor unit 41 and a processor 42. The sensor unit 41 includes one or more sensors, such as one or more cameras, one or more proximity sensors, one or more radar sensors, etc. The processor 42 is adapted to determine the position of the tightening tool 10 relative to a reference point (not shown) of the product 52 to be bolted, based on sensor data received from the sensor unit 41 when performing the tightening or loosening process of the corresponding bolts 51, 52, 53.

[0045] Figure 2 A flowchart illustrating different steps of the method according to the invention based on a basic embodiment is shown. This method is based on the consideration that monitoring the tightening process by the processing unit 20 and controlling the tightening tool 10 ensures that the worker will complete the process in the correct sequence even if problems occur. Monitoring and supervision by the processing unit 20 makes the entire tightening process easier. In case of problems, the tightening tool 10 is controlled to proceed to the correct next step, which is also output via the user interface 30.

[0046] In the first step S1, in the first operating mode, during and / or after the completion of the tightening sequence, the bolt connection parameters P1 and P2 are received from the tightening tool 10. Next, the processing unit 20 determines the state (ST) of the bolt connection when and / or after the bolt connection is completed (step S2). If state ST corresponds to the second state NOK (i.e., ST=NOK), the tightening tool 10 switches from the first operating mode to the second operating mode (step S3). In the final step S4, the tightening tool 10 switches from the second operating mode to the first tightening sequence in at least one tightening sequence of the first operating mode to re-tighten the bolts 51, 52, and 53 associated with the second state NOK.

[0047] Figures 3 to 11 The left side shows a schematic diagram of workpiece 50, where three bolts 51, 52, and 53 must be tightened by a worker using tightening tool 10. The right side shows an exemplary display screen indicating the bolting process. The display screen outputs information and guidance to the worker on the monitor 31.

[0048] As an example only, bolts 51, 52, and 53 must be tightened in two sequences: a first tightening sequence requiring, for example, a torque of 32 Nm, and a second tightening sequence requiring, for example, a final torque of 40 Nm. It is assumed that both tightening sequences are used for coupling. Figure 1 The same tightening tool 10 as described above is used. As mentioned above, the tightening tool 10 is controlled and monitored by means of the processing unit 20 with respect to necessary parameters (actuator speed, torque, etc.).

[0049] According to the work specifications, bolts 51, 52, and 53 will be tightened one after another in the first tightening sequence, followed by the second tightening sequence. The tightening process will be displayed on the screen. Figures 3 to 11 On the right side of each of them on the display screen.

[0050] Figures 3 to 5 The diagram shows the tightening of bolts 51, 52, and 53 after the first tightening sequence. A successful bolted connection after the first tightening sequence is indicated by the reference numerals 51, 52, and 53 for each bolt, their suffix " / 1," and a shading line from the lower left to the upper right.

[0051] Information about each bolt connection is displayed on the screen. The screen shows the process number PN of the current bolt connection process, along with the status ST of the result of the bolt connection process, parameters P1 and P2 acquired by the sensor unit 12 of the tightening tool 10, and the position information POS acquired by the positioning unit 40. The first parameter P1 represents, for example, the torque of the tightening process, where the torque to be achieved must be within a predetermined range. The second parameter P2 represents, for example, the angle, where the angle to be achieved must be within a predetermined range. The coordinates x / y / z of the position POS are indicated relative to a given reference point (not shown) of the workpiece 50. Any suitable coordinate system can be used.

[0052] Figure 3 The display shows that the first (left) bolt 51 has been tightened according to the first tightening sequence. Its process number on the display is PN=1. The acquired parameters P1, P2, and position POS are indicated as P1=32, P2=10, and POS=10 / 20 / 30. The processing unit 20 determines, based on the acquired parameters P1 and P2, that the status ST of bolt connection 51 / 1 is correct, i.e., ST=OK.

[0053] Figure 4 This shows that the second (intermediate) bolt 52 has been tightened according to the first tightening sequence. The process number on the display is PN=2. The acquired parameters P1, P2, and position POS are indicated as P1=32, P2=9, and POS=10 / 20 / 32. The processing unit 20 determines, based on the acquired parameters P1 and P2, that the status ST of bolt connection 52 / 1 is correct, i.e., ST=OK.

[0054] Figure 5 The display shows that the third (right) bolt 53 has been tightened according to the first tightening sequence. Its process number on the display is PN=3. The acquired parameters P1, P2, and position POS are indicated as P1=32, P2=11, and POS=10 / 20 / 34. The processing unit 20 determines, based on the acquired parameters P1 and P2, that the status ST of bolt connection 53 / 1 is correct, i.e., ST=OK.

[0055] Figures 6 to 8 The diagram shows the tightening of bolts 51, 52, and 53 after the second tightening sequence. Successful bolted connections after the second tightening sequence are indicated by the reference numerals 51, 52, and 53 for each bolt, their suffix " / 2," and crosshairs.

[0056] Figure 6This shows that the first (left) bolt 51 has been tightened according to the second tightening sequence. The process number on the display is PN=4. Alternatively, the display option line PN=1 can be overridden. The acquired parameters P1, P2, and position POS are indicated as P1=40, P2=15, and POS=10 / 20 / 30. The processing unit 20 determines, based on the acquired parameters P1 and P2, that the status ST of the bolt connection 51 / 2 is correct, i.e., ST=OK.

[0057] Figure 7 This shows that the second (intermediate) bolt 52 has been tightened according to the second tightening sequence. Its process number on the display is PN=5. Alternatively, the display option line PN=2 can be overridden. The acquired parameters P1, P2, and position POS are indicated as P1=40, P2=16, and POS=10 / 20 / 32. The processing unit 20 determines, based on the acquired parameters P1 and P2, that the status ST of bolt connection 52 / 2 is correct, i.e., ST=OK.

[0058] Figure 8 This shows that the third (right) bolt 53 has been tightened according to the second tightening sequence. Its process number on the display is PN=6. Alternatively, the display option line PN=3 can be overridden. The acquired parameters P1, P2, and position POS are indicated as P1=40, P2=30, and POS=10 / 20 / 34. The processing unit 20 determines, based on the acquired parameters P1 and P2, that the status ST of bolt connection 53 / 2 is faulty, i.e., ST=NOK. This is indicated on the display by highlighting line PN=6. Furthermore, the bolt connection of bolt 53 is indicated by 53 / F and different shaded lines.

[0059] Due to the faulty bolt connection, bolt 53 must be loosened, and both the first and second tightening sequences must be repeated. Based on the determination that state ST corresponds to NOK (second state), the tightening tool 10 automatically switches from the first operating mode (for tightening bolts) to the second operating mode (for loosening bolts), even if its rotation direction is reversed. The switching from the first operating mode to the second operating mode is performed automatically under the control of the processing unit 20.

[0060] As the next step, the worker must loosen bolt 53. To prevent the worker from loosening one of the other two correctly tightened bolts 51 and 52, the positioning unit 40 is configured to release the tightening tool 10 only when it is in the correct position to loosen bolt 53. For this purpose, the tightening unit is configured to determine the position of the tightening tool 10 during the tightening process of bolts 51, 52, and 53. If the bolt connection state ST (here: 53 / F) corresponds to NOK, the position of the tightening tool (coordinates 10 / 20 / 34 in our example) is stored as a first position in a memory not shown. When the worker intends to loosen bolt 53 (or any of the bolts), the position of the tightening tool is determined again. If the current position of the tightening tool 10 (coordinates 10 / 20 / 34) corresponds to the stored first position, the tightening tool 10 is released, thus loosening bolt 53.

[0061] Figures 9 to 11 The loosening and retightening of bolt 53 are shown. Successful bolted connections after the first tightening sequence are again indicated by the bolt's reference numeral 53 and its suffix " / 1" and a shading line from the lower left to the upper right. Successful bolted connections after the second tightening sequence are indicated by the bolt's reference numeral 53 and its suffix " / 2" and a crosshair.

[0062] Figure 9 This shows that the third (right) bolt 53 has been loosened. On the display, successful loosening is visually apparent by blocking the display of lines PN=3 and PN=6. The other lines on the display remain unchanged.

[0063] Figure 10 This shows that the third (right) bolt 53 has been tightened according to the first tightening sequence. The process number on the display is now PN=3.1. The acquired parameters P1, P2, and position POS are indicated as P1=32, P2=11, and POS=10 / 20 / 34. The processing unit 20 determines, based on the acquired parameters P1 and P2, that the status ST of bolt connection 53 / 1 is correct, i.e., ST=OK.

[0064] Figure 11 The display shows that the third (right) bolt 53 has been tightened according to the second tightening sequence. Its process number on the display is PN=6.1. The acquired parameters P1, P2, and position POS are indicated as P1=40, P2=14, and POS=10 / 20 / 34. The processing unit 20 determines, based on the acquired parameters P1 and P2, that the status ST of bolt connection 53 / 2 is now correct, i.e., ST=OK.

[0065] According to an embodiment not shown, if the state ST of a bolt connection corresponds to NOK, a counter associated with the corresponding bolt connection can be incremented by 1. This is wherein if the state ST of a bolt connection corresponds to NOK for the first time, the counter starts from a predetermined starting value (e.g., 0), and if the state ST of a bolt connection subsequently corresponds to NOK every time, the counter starts from the last stored value. Preferably, if the actual value of the counter exceeds a predetermined threshold, an indication to use a new bolt is output on the user interface. This particular embodiment can be combined with a storage system built using KANBAN logic, which enables monitoring whether a worker has actually removed a new bolt from the storage device.

[0066] In summary, the proposed method has many advantages:

[0067] It ensures the correct tightening sequence is performed even if problems arise. Furthermore, it simplifies the entire process of using the tightening system. If issues occur, it guides the worker through the process, thus preventing human error.

[0068] Because of the data connection between the tightening tool and the processing unit, potential malfunctions or worker deception are eliminated. Results of faulty connections are automatically deleted by the processing unit. Therefore, it is impossible for a worker to forget a faulty connection. Furthermore, archiving is clean for quality reasons.

[0069] With the functionality of the positioning unit, large factory structures can utilize it to ensure safe production.

[0070] Therefore, a novel worker guidance system is provided that can ensure zero-defect production in large-scale factory construction. This system can be used as the primary system for digital quality control in large-scale factory construction.

Claims

1. A method for computer-implemented supervision of a bolt tightening (100) process using a tightening system, said tightening system comprising: A manually operated tightening tool (10) includes an actuator (11) for rotating the bolt. The manually operated tightening tool (10) is configured to switch between a first operating mode and a second operating mode. In the first operating mode, the actuator (11) of the tightening tool (10) can operate in at least one tightening sequence, and in the second operating mode, the actuator (11) of the tightening tool (10) can operate in a loosening sequence. Each of the tightening sequence and the loosening sequence includes predetermined operating parameters for the actuator (11) of the tightening tool (10), and The tightening tool (10) also includes a sensor unit (12) for determining at least one parameter (P1, P2) of the bolt connection during and / or after the completion of the tightening sequence. Each of the at least one parameter (P1, P2) represents a quality measure of the bolted connection; The tightening system further includes: A processing unit (20) for processing at least one parameter (P1, P2) received from the sensor unit (12), wherein the processing unit (20) is configured to determine the state (ST) of the bolted connection based on the at least one parameter (P1, P2), wherein the state (ST) includes a first state indicating a correct bolted connection and a second state indicating a faulty bolted connection; and User interface (30) is used to output connection information about the bolted connection; The method includes the following steps: a) In the first operating mode, during and / or after the completion of the tightening sequence, at least one parameter (P1, P2) of the bolt connection is received from the tightening tool (10) via the interface (21). b) Determine the state (ST) of the bolted connection when and / or after it is completed; c) If the state (ST) corresponds to the second state, then switch the actuator (11) of the tightening tool (10) from the first operating mode to the second operating mode; and d) Switch the tightening tool (10) from the second operating mode to the first tightening sequence in at least one tightening sequence of the first operating mode to retighten the bolts (51, 52, 53). The tightening system further includes a positioning unit configured to determine the position of the tightening tool (10) relative to a reference point of the product to be bolted during the tightening or loosening process of the bolts (51, 52, 53), wherein the processing unit (20) is configured to perform the following steps: e1) During the tightening process of the bolts (51, 52, 53), determine the position of the tightening tool (10); e2) If the state of the bolt connection corresponds to the second state, then the position of the tightening tool (10) is stored as the first position; e3) Release the tightening tool (10) to loosen the bolts (51, 52, 53) associated with the second state only if the current position of the tightening tool (10) corresponds to the first position.

2. The method of claim 1, wherein, The method includes further steps: e) Control the actuator (11) of the tightening tool (10) from the first tightening sequence to at least one subsequent tightening sequence of the first operating mode to retighten the bolts (51, 52, 53) according to a predetermined order of the tightening sequence.

3. The method of claim 1 or 2, wherein, The step of switching the tightening tool (10) from the first operating mode to the second operating mode and / or switching the tightening tool (10) from the second operating mode to the first operating mode in the first tightening sequence or in a subsequent tightening sequence is performed under the automatic control of the processing unit (20).

4. The method according to claim 1, wherein, The user interface (30) outputs the status (ST) of the bolted connection and / or at least one parameter (P1, P2) representing the quality measure of the bolted connection as connection information on the display (31).

5. The method according to claim 4, wherein, The connection information is output in real time.

6. The method according to claim 1, wherein, Step d) is initiated after the following steps have been performed. cl) In the second operating mode, during and / or after the completion of the loosening sequence, at least one parameter of the bolt connection is received from the tightening tool (10); and c2) Determine whether the bolted connection has been completely loosened.

7. The method according to claim 6, wherein, The user interface (30) immediately prevents the display of the bolted connection after step c2) is completed.

8. The method according to claim 1, wherein, If the state of the bolted connection corresponds to the second state, the counter associated with the corresponding bolted connection is incremented by 1, wherein if the state of the bolted connection corresponds to the second state for the first time, the counter starts from a predetermined starting value, and if the state of the bolted connection corresponds to the second state every time thereafter, the counter starts from the last stored value.

9. The method according to claim 8, wherein, If the actual value of the counter exceeds a predetermined threshold, an instruction to use new bolts (51, 52, 53) is output on the user interface (30).

10. An apparatus for computer-controlled monitoring of the tightening process of bolts (51, 52, 53) using a tightening system, comprising: A manually operated tightening tool (10) comprising: an actuator (11) for rotating the bolt, the manually operated tightening tool (10) being configured to switch between a first operating mode and a second operating mode, wherein in the first operating mode the actuator (11) of the tightening tool (10) can operate according to at least one tightening sequence, and in the second operating mode the actuator (11) of the tightening tool (10) can operate according to a loosening sequence, each of the tightening sequence and the loosening sequence comprising predetermined operating parameters for the actuator (11) of the tightening tool (10); and a sensor unit for determining at least one parameter of the bolt connection during and / or after the completion of the tightening sequence, each of the at least one parameter representing a quality measure of the bolt connection; A processing unit (20) for processing at least one parameter received from the sensor unit, wherein the processing unit (20) is configured to determine the state of the bolted connection based on the at least one parameter, the state including a first state indicating a correct bolted connection and a second state indicating a faulty bolted connection; and User interface (30) is used to output connection information about the bolted connection; The processing unit (20) is configured to perform the following steps: a) In the first operating mode, during and / or after the completion of the tightening sequence, at least one parameter of the bolt connection is received from the tightening tool (10); b) Determine the state of the bolted connection when and / or after it is completed; c) If the state corresponds to the second state, then switch the actuator (11) of the tightening tool (10) from the first operating mode to the second operating mode; d) Switch the tightening tool (10) from the second operating mode to the first tightening sequence in at least one tightening sequence of the first operating mode to retighten the bolts (51, 52, 53). The tightening system further includes a positioning unit configured to determine the position of the tightening tool (10) relative to a reference point of the product to be bolted during the tightening or loosening process of the bolts (51, 52, 53), wherein the processing unit (20) is configured to perform the following steps: e1) During the tightening process of the bolts (51, 52, 53), determine the position of the tightening tool (10); e2) If the state of the bolt connection corresponds to the second state, then the position of the tightening tool (10) is stored as the first position; e3) Release the tightening tool (10) to loosen the bolts (51, 52, 53) associated with the second state only if the current position of the tightening tool (10) corresponds to the first position.

11. The apparatus according to claim 10, wherein, The apparatus is configured to perform the method according to any one of claims 2 to 9.

12. A computer program product having program code stored on a non-transitory machine-readable medium for performing the method according to any one of claims 1 to 9 when the program code is executed on a computer.

13. A wind turbine comprising a bolted connection including at least three bolts (51, 52, 53) and the device according to claim 10 or 11, or comprising a bolted connection including at least three bolts (51, 52, 53), wherein, The bolts (51, 52, 53) are tightened by performing the method according to any one of claims 1 to 9.

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