Control device and method for controlling a plurality of fastening tools arranged together in a fixture

Abstract

The present description relates to a control device (2) for controlling a plurality of fastening tools (4) arranged together in a fixture (3). Each tool comprises a motor (7) for driving a fastening operation and a transmission (8) connected to the motor (7). The control device is configured to: acquire parameters for each tool indicating the efficiency of the transmission of the tool in conjunction with the fastening operations performed simultaneously by the tools; and to issue a notification to a user in response to the acquired parameters of any one tool deviating to a certain extent from at least some of the acquired parameters of the other tools. The tools can then be maintained based on actual need rather than according to a predetermined scheme. The risk of performing maintenance earlier or later than actually required is reduced, which in turn improves manufacturing efficiency and reduces costs.

Description

Technical Field

[0001] The present invention generally relates to the field of controlling fastening tools arranged together in a fixture and configured to perform simultaneous fastening operations. Background Art

[0002] In manufacturing, a group of tightening tools arranged together in a fixture are used to perform simultaneous tightening operations on similar types of joints. An example is the assembly of a vehicle, where such fixed tools are used to tighten the wheel bolts simultaneously when the wheel is mounted to the hub. Each tool in the fixture typically includes a motor and a gear set for transmitting torque from the motor to the output shaft of the tool. Over time, dust and particles may collect in the gears and lubrication may gradually deteriorate. Therefore, in order to avoid becoming too inefficient over time and to reduce the risk of gear failure, the gears require regular maintenance, which may cause the assembly process to stop. If a gear breaks, it may be difficult to replace due to the nature of the fixed tool. Maintenance is usually carried out according to a schedule. The disadvantage of this is that there is a risk that maintenance may be carried out earlier or later than it is actually necessary, which in turn may reduce manufacturing efficiency and increase costs. Summary of the invention

[0003] It would be advantageous to achieve a solution that overcomes or at least mitigates the above disadvantages. In particular, it would be desirable to be able to achieve a control device and method that can improve the maintenance of fixed fastening tools.

[0004] In order to better solve one or more of these problems, a control device and a method are provided having the features defined in the independent claims. Preferred embodiments are defined in the dependent claims.

[0005] Thus, according to a first aspect, there is provided a control device configured to control a plurality of fastening tools arranged together in a fixture. Each tool comprises a motor for driving a fastening operation and a transmission connected to the motor. The control device is configured to: acquire a parameter for each tool indicative of the efficiency of the transmission of the tool in conjunction with the fastening operations simultaneously performed by the tools; and issue a notification to a user in response to the acquired parameters of any one tool deviating to some extent from at least some of the acquired parameters of the other tools.

[0006] According to a second aspect, a method is provided for controlling a plurality of fastening tools arranged together in a fixture. Each tool comprises a motor for driving a fastening operation and a transmission connected to the motor. The method comprises: acquiring a parameter for each tool indicative of the efficiency of the transmission of the tool in conjunction with the fastening operations simultaneously performed by the tools; and in response to the acquired parameters of any one tool deviating to some extent from at least some of the acquired parameters of the other tools, issuing a notification to a user.

[0007] The inventors have realized that in a fixed tool, the fact that the tool is multiple and performs the same type of simultaneous tightening operation in the same environment can be used to detect abnormal performance of one of the tools. Tools with normal performance can be used as a comparison for tools that detect performance abnormalities (which may indicate the need for maintenance). This can be achieved by observing the parameters of each tool that indicate the efficiency of the transmission device of the tool. Reduced efficiency of the transmission device may indicate that maintenance may be required. Therefore, if the acquired parameters of one tool deviate from at least some of the acquired parameters of other tools to some extent, a notification can be issued so that the user / operator can check the tool and maintain the tool if necessary. Then, the tool can be maintained based on actual needs rather than according to a predetermined scheme. Therefore, the risk of performing maintenance earlier or later than actually required is reduced, which in turn improves manufacturing efficiency and reduces costs.

[0008] According to an embodiment, the acquired parameters for each tool may be indicative of one or more of: temperature at or near the motor; and motor current.

[0009] Over time, the efficiency of the gears gradually decreases, which will gradually increase the load on the tool's motor. The increased load on the motor will cause the temperature of the motor to increase, and the motor will require a higher current to produce the required torque. Therefore, in order to detect abnormal performance of the tool, any one of these parameters may be suitable for observation. However, it should be understood that any parameter that indicates the efficiency of the transmission can be utilized, for example, any parameter that can be measured and is affected by the degree of gear efficiency.

[0010] According to an embodiment, parameters of each tool may be acquired at one or more of the following points in time: at the start of (simultaneous) the tightening operation; during the tightening operation; at the end of the tightening operation; and a predetermined period of time, e.g., a few seconds, after the tightening operation is terminated.

[0011] During repeated use of a stationary tool, the motor temperature will gradually increase, especially in tools that require maintenance. Since the temperature changes relatively slowly, the motor temperature can be sampled at any time in conjunction with the simultaneous tightening operation, for example, some time after the simultaneous tightening operation has terminated. On the other hand, if the parameter being monitored is the motor current, it is best to sample the parameter at some time during the tightening operation when the motor is running.

[0012] Determining when the acquired parameters of any one tool deviate to a certain extent from at least some of the acquired parameters of the other tools can be accomplished in different ways.

[0013] For example, the control device may be further configured to: determine a comparison value based on the acquired parameters of the tool; compare each acquired parameter to the comparison value; and issue a notification in response to any one of the acquired parameters deviating from the comparison value by a predetermined degree or more. For example, each acquired parameter value may be compared to the comparison value, and a notification may be issued if it deviates from the comparison value by more than a predetermined amount. An advantage of this embodiment is that it requires relatively little computing power because each acquired parameter only needs to be compared to a single value (the comparison value).

[0014] For example, the comparison value may be a statistical parameter based on the acquired parameter, such as a mean or median of the acquired parameter, or a value provided by any other type of suitable statistical function.

[0015] Alternatively (or in addition), the control device can be configured to: compare each acquired parameter with each of the other acquired parameters; based on the comparison results, determine the average deviation of the parameters of each tool from the acquired parameters of the other tools; and issue a notification in response to any one of the determined average deviations being greater than a predetermined value.

[0016] According to an embodiment, the control device may be further configured to: for a continuous array of simultaneous tightening operations, repeatedly obtain the parameters of each tool, and for multiple continuous arrays of simultaneous tightening operations, only notify the user in response to the obtained parameters of any one tool deviating to a certain extent from at least some of the obtained parameters of other tightening tools. The advantage of this embodiment is that it provides a more robust alarm system for abnormal performance.

[0017] According to an embodiment, the control device may be further configured to: obtain tracking data of the tightening operation; and before issuing a notification to the user, consider the tracking data when determining to what extent each obtained parameter is allowed to deviate from at least some of the other obtained parameters. The tracking data may be data indicating the tightening parameters changing over time. The tracking data may include, for example, the tightening torque and the angle of the tightening operation changing over time. Therefore, the allowed deviation may increase with increasing angle / torque.

[0018] According to an embodiment, the degree to which the acquired parameters of each tool are allowed to deviate from the other acquired parameters may be pre-set or determined simply through machine learning.

[0019] According to an embodiment, a system is provided. The system comprises a plurality of fastening tools arranged together in a fixture and a control device according to any of the above embodiments, wherein each tool comprises a motor for driving a fastening operation and a transmission connected to the motor.

[0020] According to an embodiment, there is provided a computer program product comprising instructions which, when executed by a computer (eg a control device), cause the computer to perform the method according to the second aspect.

[0021] According to an embodiment, there is provided a computer readable medium comprising instructions which, when executed by a computer (eg a control device), cause the computer to perform the method according to the second aspect.

[0022] It should be noted that the embodiments of the present invention relate to all possible combinations of features described in the claims. In addition, it should be understood that the various embodiments described for the control device can be combined with the method defined according to the second aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] These and other aspects will now be described in more detail in the following illustrative and non-limiting detailed description of embodiments, with reference to the accompanying drawings.

[0024] Figure 1 A system according to an embodiment is shown.

[0025] Figure 2 A tool according to an embodiment is shown.

[0026] Figure 3 A method according to an embodiment is shown.

[0027] All the drawings are schematic, not necessarily to scale, and generally show only those parts which are necessary for explaining the embodiments, wherein other parts may be omitted. Throughout the specification, like reference numerals denote like elements. DETAILED DESCRIPTION

[0028] Will refer to Figure 1A system 1 according to an embodiment is described. The system 1 includes a set of fastening tools 4 arranged together in a fixture 3. Thus, the tools 4 are arranged in a fixed relationship to each other so that simultaneous fastening operations can be performed. In this example, a set of three tools 4 are arranged in the fixture 3. However, any other number of tools can also be envisioned. The tool 4 can be, for example, a screwdriver or a nut wrench. Each tool 4 can include an output shaft 5, to which a socket can be attached, for example. The fixture 3 can be manipulated by an operator via a handle 6. The fixed tool 4 can communicate with the control device 2. The control device 2 is configured to control the fixed tool 4. For example, the control device 2 can be configured to provide a fastening program for performing a fastening operation to the tool 4. In addition, the control device 2 can be configured to collect tracking data from the fixed tool 4, for example, torque and angle, temperature readings and current of the fastening operation performed. In this example, the control device 2 is a centralized control device arranged separately from the fixed tool 4. The centralized control device 2 can optionally be configured to control several tool fixtures 3. Alternatively (not shown), the control device can be arranged in the tool fixture 3 itself.

[0029] The control device 2 includes a processing circuit. The control device 2 may be, for example, a computer. The processing circuit may be configured to execute steps to perform the method disclosed herein. The processing circuit may, for example, utilize any combination of one or more of a suitable central processing unit (CPU), a multiprocessor, a microcontroller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), etc.

[0030] The control device 2 may include a storage medium, which includes a computer program, which, when executed by a processing circuit, performs the steps of the method disclosed herein. The storage medium may be embodied as a memory, for example.

[0031] The control device 2 may further include a communication module configured to perform data communication with the tool 4 .

[0032] Now go to Figure 2 , these tools will be described in more detail. Each tool 4 comprises a motor 7 and a gear set 8 arranged to transmit the torque generated by the motor 7 to an output shaft 5. Each tool 4 may be provided with a temperature sensor 10 arranged to sense the temperature in or near the motor 7. The temperature sensor 10 may be in communication with the control device 2.

[0033] Go to again Figure 1, the function of the system 1 will now be described. The control device 2 is configured to acquire (determine) a parameter for each tool 4 indicating the efficiency of the transmission device of the tool 4 in conjunction with the tightening operations performed simultaneously by the tools 4. The parameter may be, for example, the motor current applied during the tightening operation and / or the temperature sensed by the temperature sensor 10, or any other parameter indicating the efficiency of the transmission device of the tool 4. The parameter may be acquired, for example, by the tool 4 transmitting data indicating the motor current and / or the motor temperature to the control device 2.

[0034] The parameter indicative of the efficiency of the transmission of the tool 4 may be acquired (determined) for example at the beginning, sometime during, at the end or some time after the simultaneous start operation. In the case where the parameter is the motor current, it may be sampled at any time while the motor is running.

[0035] During the simultaneous tightening operation, the temperature will increase in the motor 7. Taking into account the current state of efficiency of the gears 8 of each tool, a certain current will be required to operate the motor 7. During repeated simultaneous tightening operations, the temperature of each set of simultaneous tightening will increase.

[0036] The control device 2 is further configured to issue a notification to the user / operator in response to the acquired parameters of any one tool 4 deviating to some extent from at least some of the acquired parameters of the other tools 4 (e.g., deviating from all other tools in the fixture participating in the simultaneous tightening operation). The notification can be, for example, a visual and / or audio message on a display connected to the control device 2. The user can then understand that a performance anomaly of the tool 4 needs to be checked and possibly maintained.

[0037] It should be understood that not all tools 4 in the fixture 3 must be operated simultaneously. For example, only three out of five tools may be used during a particular tightening operation. Parameter comparisons can then be made only between the tools that were active during the tightening operation.

[0038] In order to detect abnormal performance of any one of the tools 4, the control device 2 may be configured to determine a comparison value based on the acquired parameters of the tools 4. The comparison value may be, for example, a statistical parameter based on the acquired parameters, such as an average or median value of the acquired parameters. As an example, if the temperature of two of the three tools 4 is 60°C and the temperature of the third is 70°C, the comparison value may be determined as (60+60+70) / 3=63°C. The control device 2 may be further configured to compare each acquired parameter with the comparison value. Thus, in this example, each of the determined parameters 60°C, 60°C and 70°C is compared with the comparison value of 63°C, respectively. The control device 2 may be further configured to issue a notification in response to any one of the acquired parameters deviating from the comparison value to a predetermined degree or more. In this example, the allowable deviation from the comparison value may have been preset to, for example, 5°C. The two 60°C parameters deviate from the comparison value of 63°C by -3°C each, while the 70°C parameter deviates from the comparison value of 63°C by 7°C. Since one of the deviations exceeds the threshold of 5° C., a notification will be issued to the user that this tool of the tool 4 needs to be checked.

[0039] As an alternative (or in addition), the control device 2 can be configured to compare each acquired parameter with each of the other acquired parameters and determine the average deviation of the parameters of each tool 4 from the acquired parameters of the other tools 4 based on the comparison results. When applied to the current temperature example, the average deviation of a tool with a temperature of 60°C from the other tools (temperatures of 60°C and 70°C) will be ((60-60)+(60-70)) / 2=-5°C, while the average deviation of a tool with a temperature of 70°C will be ((70-60)+(70-60) / 2=10°C. The control device 2 can be further configured to issue a notification in response to any determined average deviation being greater than a predetermined value. In this example, if the maximum allowable deviation is, for example, 7°C, a notification will be issued.

[0040] According to an embodiment, a notification is issued only if the deviation of one of the determined parameters exceeds a range allowed for several repeated tightening operations.

[0041] According to an embodiment, the control device 2 may also take into account the tracking data of the tightening operation when determining the extent to which each acquired parameter is allowed to deviate, before issuing a notification to the user.

[0042] exist Figure 3 , a method 100 according to an embodiment is shown. The method 100 includes: acquiring 101 parameters for each tool indicating the efficiency of the transmission device of the tool in conjunction with the tightening operations performed simultaneously by the tools; and in response to the acquired parameters of any one tightening tool deviating to some extent from at least some of the acquired parameters of the other tools, issuing 102 a notification to a user.

[0043] It should be understood that the method 100 may further include any one of the above steps that the control device 2 may be configured to perform.

[0044] It will be appreciated by those skilled in the art that the present invention is by no means limited to the embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims.

[0045] Moreover, variations to the disclosed embodiments may be understood and effected by a skilled person practicing the claimed invention through a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. A control device (2) configured to control a plurality of fastening tools (4) arranged together in a fixture (3), in, Each tool comprises a motor (7) for driving the tightening operation and a transmission (8) connected to the motor (7), The control device is configured as follows: obtaining, in connection with each of a continuous array of fastening operations simultaneously performed by the tool, a parameter for each tool indicative of an efficiency of a transmission of the tool; For multiple consecutive arrays of simultaneous tightening operations, notification is only issued to the user in response to the acquired parameters of any one tool deviating to some extent from at least some of the acquired parameters of the other tools.

2. The control device according to claim 1, wherein: The parameters indicate one or more of the following: The temperature at or near the motor; and Motor current.

3. The control device according to claim 1 or 2, wherein: Get the parameters for each tool at one or more of the following points in time: At the start of the tightening operation; During tightening operations; At the end of the tightening operation; as well as A predetermined period of time, for example, a few seconds, after the tightening operation is terminated.

4. The control device according to any one of the preceding claims, further configured to: determining a comparison value based on the acquired parameters of the tool; Compare each obtained parameter with a comparison value; In response to any one of the acquired parameters deviating from the comparison value by a predetermined degree or more, a notification is issued.

5. The control device according to claim 4, wherein: The comparison value is based on a statistical parameter of the acquired parameter, for example, a mean value or a median value of the acquired parameter.

6. The control device according to any one of the preceding claims, further configured to: Compare each acquired parameter with each of the other acquired parameters; Based on the comparison results, determining the average deviation of the parameters of each tool from the parameters obtained by the other tools; In response to any of the determined average deviations being greater than a predetermined value, a notification is issued.

7. The control device according to any one of the preceding claims, further configured to: Obtain tracking data on fastening operations; The tracking data is considered in determining how much each acquired parameter is allowed to deviate from at least some of the other acquired parameters before issuing a notification to the user.

8. A system (1), comprising: a plurality of fastening tools (4) arranged together in a fixture (3), Each tool comprises a motor (7) for driving the tightening operation and a transmission device (8) connected to the motor (7), and A control device (2) according to any one of the preceding claims.

9. A method (100) for controlling a plurality of fastening tools arranged together in a fixture, in, Each tool includes a motor for driving the tightening operation and a transmission connected to the motor, The method comprises: acquiring (101) for each tool a parameter indicative of the efficiency of a transmission of the tool in connection with each of a continuous array of tightening operations simultaneously performed by the tool; For multiple consecutive arrays of simultaneous tightening operations, notification is issued (102) to the user only in response to the acquired parameters of any one tool deviating to some extent from at least some of the acquired parameters of the other tools.

10. A computer program product comprising instructions which, when executed by a computer, cause the computer to perform the method of claim 9.

11. A computer readable medium comprising instructions which, when executed by a computer, cause the computer to perform the method of claim 9.

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