Grinding machine and robot

Abstract

The system detects the worn condition of a grinding wheel tool. A grinding machine comprises: a grinding wheel tool configured to rotate around a rotating shaft; a force sensor configured to detect a torque around the rotating shaft, the torque acting on the grinding wheel tool; and a controller, the controller performing a detection process of recognizing a worn condition of the grinding wheel tool based on the torque received from the force sensor.

Description

Technical field

[0001] The present invention relates to a grinding machine and a robot. background

[0002] JP 2010-269396 discloses a disc grinding machine comprising a circular grinding wheel (hereinafter also referred to as the "disc tool") which is driven by a motor to rotate. The disc tool rotates around an output shaft through which the rotation of the motor is transmitted. Summary Technical Problem

[0003] The grinding wheel tool wears down through use. The worn grinding wheel tool must be replaced. However, in the grinding wheel machine disclosed in JP 2010-269396, there is no method for detecting a worn state of the grinding wheel tool, other than making a determination based on the operator's subjective opinion.

[0004] One objective of the present invention is to detect a worn state of a disc tool. Solution to the problem

[0005] To solve the above problem, a grinding machine according to one aspect of the present invention comprises: a disc tool configured to rotate about a rotating shaft; a force sensor configured to detect a torque about the rotating shaft, the torque acting on the disc tool; and a controller, the controller performing a detection process of sensing / detecting a worn condition of the disc tool based on the torque obtained from the force sensor. Advantageous effects of the invention

[0006] According to one aspect of the present invention, it is possible to detect a worn state of a disc tool. Brief description of the drawings Fig. Figure 1 is a schematic side view illustrating an embodiment of a grinding machine according to one embodiment of the present invention. Fig. Figure 2 is a schematic view to illustrate an example of a worn condition of a disc tool. Fig. Figure 3 is a block diagram illustrating an example of the internal design of a grinding machine. Fig. Figure 4 is a flowchart illustrating an example of a process procedure executed by a controller. Description of the embodiments [versions]

[0007] The following description will discuss in detail a grinding machine 1 according to an embodiment of the present invention. (Overview of the grinding machine)

[0008] With reference to Fig. The following section describes an overview of the grinding machine 1. Fig. Figure 1 is a schematic side view illustrating an embodiment of the grinding machine 1 according to one embodiment of the present invention. The grinding machine 1 comprises a grinding wheel 20, a force sensor 40, and a control unit 80. The grinding machine 1 may further comprise a main body 10, a drive motor 30, an inertial measurement unit (IMU) 50, and an input device 60 (see Figure 1). Fig. 3) and include an ad 70.

[0009] The main body 10 forms a main part of the grinding machine 1. For the main body 10, an x-axis direction (direction of an x-axis) is considered a longitudinal direction. The main body 10 has a first end part 11 and a second end part 12, which is arranged opposite the first end part 11. The first end part 11 is an end part arranged on a negative side in the x-axis direction. The second end part 12 is an end part arranged on a positive side in the x-axis direction.

[0010] A gripping element 13 is provided on one side closer to the first end part 11 of the main body 10. The gripping element 13 is designed to have a small diameter, which facilitates easier gripping by an operator. The gripping element 13 can accommodate the IMU 50 and the controller 80 within it. A power source button 61, located in the input device 60 (see Fig. 3) is included, can be provided on the negative direction side in the z-axis direction of the gripping part 13.

[0011] The disc tool 20 is attached on one side closer to the second end part 12 of the main body 10. More precisely, the disc tool 20 is attached to a negative directional side in a z-axis direction of a gear mounting part 14, which is located on the side closer to the second end part 12 of the main body 10. The gear mounting part 14 can accommodate the drive motor 30 and the force sensor 40. A side handle can be attached to the gear mounting part 14 for use by an operator.

[0012] The disc tool 20 is a tool for machining, such as polishing, a workpiece 2. Examples of disc tools 20 include a grinding wheel. The disc tool 20 is attached to a spindle 32 using, for example, nuts. The disc tool 20 rotates around the spindle 32. The spindle 32 serves as a rotating shaft for the disc tool 20.

[0013] The drive motor 30 is a motor configured to rotate the spindle 32. The spindle 32 is connected to an output shaft 31 of the drive motor 30.

[0014] The force sensor 40 detects a torque around the spindle 32, with the torque acting on the disc tool 20. The force sensor 40 outputs a signal to the controller 80 indicating the detected torque. The force sensor 40 can also detect forces acting on the disc tool 20. In this case, the force sensor 40 outputs a signal to the controller 80 indicating the detected force.

[0015] The force sensor 40 can be mounted on a flange part 35 that projects from an outer circumferential part of the drive motor 30. A through-hole 41 is formed in a central part of the force sensor 40, through which the output shaft 31 of the drive motor 30 and the spindle 32 are inserted.

[0016] In the present embodiment, a six-axis force sensor is used as the force sensor 40. The force sensor 40 detects a force Fx in an x-axis direction, a force Fy in a y-axis direction, a force Fz in a z-axis direction, a moment Mx about an x-axis, a moment My about a y-axis, and a moment Mz about a z-axis acting on the disc tool 20. Here, the x-axis direction is a direction from the first end part 11 to the second end part 12 of the main body 10. The z-axis direction is a direction parallel to an axis of the spindle 32 of the disc tool 20, being orthogonal to the x-axis. The y-axis direction is a direction orthogonal to both the x-axis and the z-axis. The x-axis direction and the y-axis direction are directions parallel to a radial direction of the disc tool 20.

[0017] The IMU 50 is an inertial measurement device designed to detect the angular velocities and accelerations of the main body 10. Specifically, the IMU 50 can detect angular velocities about the x-axis, y-axis, and z-axis of the main body 10. The IMU 50 can also detect accelerations along the x-axis, y-axis, and z-axis of the main body 10. The position (pose, orientation) of the main body 10 can be detected using the IMU 50. The IMU 50 outputs a signal to the controller 80 indicating the detected angular velocity and another indicating the detected acceleration.

[0018] The display 70 shows an image indicating the position of the disc tool 20 relative to the workpiece 2. Examples of the display 70 include a display field. The display 70 is provided on the main body 10. In the present embodiment, the display 70 is provided on the gripping part 13. The display 70 is provided in a position visible to an operator gripping the gripping part 13.

[0019] Control unit 80 controls the parts of grinding machine 1. (Internal design of the grinding machine) With reference to Fig. Section 3 below describes an example of an internal design of the grinding machine 1. Fig. Figure 3 is a block diagram illustrating an example of an internal design of the grinding machine 1.

[0020] The controller 80 includes a processor 81, a primary memory 82, a secondary memory 83, and an input / output interface (IF) 84, as shown in Fig. Figure 3 illustrates this. The processor 81, the primary memory 82, the secondary memory 83, and the input / output IF 84 are interconnected via a bus. Examples of a device that can be used as the controller 80 include a workstation.

[0021] The secondary memory 83 stores a control program P. The processor 81 loads the control program P stored in the secondary memory 83 into the primary memory 82. The processor 81 then executes processes contained in a process procedure M1 (described later) according to instructions contained in the control program P loaded into the primary memory 82.

[0022] Examples of a device that can be used as the processor 81 include a central processing unit (CPU). Examples of a device that can be used as the primary memory 82 include semiconductor random-access memory (RAM). Examples of a device that can be used as the secondary memory 83 include a hard disk drive (HDD).

[0023] The input / output interface 84 is an interface for communicating with the force sensor 40, the IMU 50, the input device 60, the display 70, and an inverter 90. Examples of interfaces for the input / output interface 84 include a Universal Serial Bus (USB), an Advanced Technology Attachment (ATA), a Small Computer System Interface (SCSI), serial communication, and the like.

[0024] The input device 60 is a device that can receive input from the operator. The input device 60 can be, for example, a button, a switch, a touch panel, or the like. In the present embodiment, the input device 60 comprises the power source button 61 and a selection button 62. The selection button 62 is a button for entering tool information for the grinding wheel tool 20. Pressing the selection button 62 by the operator causes the tool information for a new grinding wheel tool 20, which is mounted on the grinding machine 1, to be entered. The tool information includes outside diameter information for an unworn grinding wheel tool 20 that has not been used and / or type information for the grinding wheel tool 20.

[0025] The grinding machine 1 can further include the inverter 90. The inverter 90 controls the speed of the drive motor 30. The inverter 90 is an example of a speed control device. The controller 80 performs pulse-width modulation (PWM) control via the inverter 90. In particular, the controller 80 sets a duty cycle and outputs a PWM signal, generated based on the set duty cycle, to the inverter 90 via the input / output interface 84. The inverter 90 controls a current supplied to the drive motor 30 by applying a voltage to the drive motor 30, generated based on the input PWM signal. The voltage applied by the inverter 90 is controlled, thereby controlling the speed of the drive motor 30. (Process flow through the control system)

[0026] Next, with reference to Fig. 4 The following describes an example of a process procedure M1 executed by the control unit 80. Fig. Figure 4 is a flowchart illustrating an example of process procedure M1 executed by control unit 80.

[0027] First, processor 81 executes a receive process S1. In the receive process S1, processor 81 receives an output signal via input / output interface 84, which is output by force sensor 40.

[0028] The processor 81 then executes a data acquisition process S2. In data acquisition process S2, the processor 81 detects the worn state of the disc tool 20 based on the torque Mz obtained from the force sensor 40. In data acquisition process S2, the processor 81 calculates the outer diameter of the disc tool 20 as the worn state of the disc tool 20. In data acquisition process S2, the processor 81 can also calculate the thickness of the disc tool 20 as the worn state of the disc tool 20.

[0029] With reference to Fig. 2 below describes an example of recording a worn condition of the disc tool 20. Fig. Figure 2 is a schematic view to illustrate an example of a worn condition of the disc tool 20. Fig. Figure 2 is a view of the disc tool 20 seen from an axial direction of the spindle 32. The outer diameter D1 of the disc tool 20, which is indicated by the reference numeral 100 in Figure 2, is shown in Figure 2. Fig. 2 is illustrated, is larger than the outer diameter D2 of the disc tool 20, which is indicated by the reference numeral 101 in Fig. Figure 2 illustrates this. When the disc tool 20 is used, the disc tool 20 will wear down. For example, when the disc tool 20 is used, the outer diameter of the disc tool 20 can be reduced.

[0030] The torque Mz acting on the disc tool 20 is proportional to the size of the outer diameter of the disc tool 20. A smaller outer diameter of the disc tool 20 results in a smaller torque Mz acting on the disc tool 20. For example, the torque Mz acting on the disc tool 20, which is indicated by reference numeral 101 in Fig. 2 is illustrated, smaller than the moment Mz acting on the disk tool 20, which is indicated by the reference numeral 100 in Fig. Figure 2 illustrates this. The processor 81 detects a worn state of the disc tool 20 by calculating an outer diameter of the disc tool 20 based on the torque Mz.

[0031] The processor 81 then executes a speed control process S3. In the speed control process S3, the processor 81 controls the inverter 90 based on the torque Mz obtained from the force sensor 40, so that the speed of the drive motor 30 becomes a target value corresponding to the outer diameter of the disc tool 20.

[0032] In speed control process S3, processor 81 can control inverter 90 to maintain a constant peripheral speed of the disc tool 20. Specifically, in speed control process S3, processor 81 controls inverter 90 to prevent the peripheral speed of the disc tool 20 from exceeding a limit speed (hereinafter referred to as the "maximum operating peripheral speed") within which the disc tool 20 can be used safely. The maximum operating peripheral speed is set, for example, by an industrial safety and health regulation.

[0033] Next, processor 81 executes a notification process S4. In notification process S4, processor 81 sends a notification to the operator to replace the disc tool 20 if the torque Mz received from force sensor 40 falls below a threshold value. In notification process S4, processor 81 delivers the notification to the operator, for example, by causing display 70 to show a screen indicating that the disc tool 20 needs to be replaced. In this case, processor 81 generates a screen to be displayed on display 70. In notification process S4, processor 81 can be configured to deliver the notification to the operator by, for example, emitting a warning tone or a voice message using an output device such as a loudspeaker.

[0034] The threshold used in the notification process S4 is a value determined in advance based on a factor such as the type, outer diameter, or circumferential speed of the disc tool 20. The threshold can be a value set according to the tool information for the disc tool 20 entered via selection button 62 of the input device 60. That is, the threshold can be set according to the outer diameter information and / or the type information of the disc tool 20 entered using selection button 62 of the input device 60.

[0035] The notification that triggers a change of the disc tool 20 is not limited to an embodiment in which a display screen is shown on the display 70. For example, in notification process S4, processor 81 can execute the notification to the operator by sounding an alarm. In notification process S4, processor 81 only needs to be configured to execute the notification to the operator acoustically and / or visually.

[0036] As described above, the fact that the grinding machine 1 includes the force sensor 40 enables the detection of the torque Mz around a rotating shaft of the spindle 32 of the disc tool 20. This allows the detection of a worn condition of the disc tool 20.

[0037] Typically, a smaller outer diameter of the disc tool 20 results in a lower peripheral speed of the disc tool 20. The controller 80, which performs the speed control process S3, allows the speed of the drive motor 30 to be controlled according to the wear condition of the disc tool 20, which is detected using the torque Mz obtained from the force sensor 40. This makes it possible to keep the peripheral speed of the disc tool 20 constant. It is also possible to implement a control to prevent the peripheral speed of the disc tool 20 from exceeding the maximum operating peripheral speed.

[0038] The control unit 80, which executes the notification process S4, allows the operator to identify a time to replace the disc tool 20. This also allows the operator to set the replacement time, corresponding to the outer diameter information and / or the type information of the disc tool 20, by entering the tool information of the disc tool 20 by pressing the selection button 62. This enables the disc tool 20 to be replaced at the replacement time that corresponds to the outer diameter and / or the type of the disc tool 20. [Other embodiments]

[0039] In the embodiment described above, the output shaft 31 of the drive motor 30 and the spindle 32, which serves as a rotating shaft for the disc tool 20, are arranged as parallel shafts, but this configuration should not be considered a limitation. The output shaft 31 and the spindle 32 can be intersecting shafts. In this case, the force sensor 40 can be attached to a retaining element that holds the spindle 32. Furthermore, the drive motor 30 can be arranged inside the gripping part 13.

[0040] In the embodiment described above, the grinding machine 1 is configured to include the IMU 50, but this configuration should not be interpreted as a limitation. The grinding machine 1 may include an angular velocity sensor capable of detecting at least one of the angular velocities about the x-axis, the y-axis, and the z-axis. The grinding machine 1 may also include an accelerometer capable of detecting at least one of the accelerations in the x-axis, y-axis, and z-axis directions.

[0041] In the embodiment described above, the grinding machine 1 is configured to include the display 70, but this configuration should not be interpreted as a limitation. The main body 10 of the grinding machine 1 can be equipped with a display, such as an LED array or the like. In this case, the processor 81 can illuminate the display in the notification process S4 to prompt the operator to replace the grinding wheel 20. An embodiment is also possible in which an external display is connected to the grinding machine 1. In this case, the processor 81 can output a visual signal, indicating a generated display image, to the external display in the notification process S4, causing the display to show the image that prompts a replacement of the grinding wheel 20.

[0042] In the embodiment described above, the input device 60 is configured to include the selection button 62, but this configuration should not be interpreted as a limitation. The input device 60 can include an initialization button instead of the selection button 62. An embodiment is possible in which, when the disc tool 20 is replaced with a new one, the operator presses the initialization button, thus initializing the rotational speed of the drive motor 30. In this case, the threshold used in the notification process S4 can be a value obtained by reducing a predetermined percentage of the torque Mz value, which is detected in the initial processing after pressing the initialization button.

[0043] In the embodiment described above, an configuration is used in which the inverter 90 is used to control the speed of the drive motor 30, but this configuration should not be considered a limitation. A device comprising a triac element can be used as the speed control device configured to control the speed of the drive motor 30. In this case, the speed control device is phase-controlled. The speed control device can apply a voltage generated based on phase control to the drive motor 30.

[0044] In the embodiment described above, the grinding machine 1 is described as a grinding machine operated by a human operator, but this should not be interpreted as a limitation. The grinding machine 1 described above can be mounted on a robot. In this case, the controller 80 functions as a device configured to control the operation of a robot that incorporates the grinding machine 1. The controller 80, which controls the robot, can execute an exchange process, causing the robot to replace the grinding wheel 20, based on the detection of the worn condition of the grinding wheel 20.In particular, if the controller 80 determines that the worn condition of the disc tool 20, as detected in the detection process S2, indicates that the disc tool 20 is worn to the point where it needs to be replaced, the controller 80 initiates the replacement process. During the replacement process, the controller 80 causes the robot to replace the disc tool 20. According to this embodiment, if the controller 80 detects that the disc tool 20 has worn to the point where replacement is necessary, the controller 80 causes the robot to automatically replace the disc tool 20. This reduces the operator's working time by the amount required to replace the disc tool 20.

[0045] Aspects of the present invention can also be expressed as follows: A grinding machine according to aspect 1 of the present invention comprises: a disc tool configured to rotate about a rotating shaft (axis of rotation); a force sensor configured to detect a torque about the rotating shaft, wherein the torque acts on the disc tool; and a control system, wherein the control system performs a detection process of detecting a worn condition of the disc tool based on the torque obtained from the force sensor.

[0046] According to the design of aspect 1, the fact that the grinding machine includes the force sensor enables the detection of a torque around a rotating shaft of the grinding wheel tool. This allows the detection of a worn condition of the grinding wheel tool.

[0047] A grinding machine according to aspect 2 of the present invention can be configured in aspect 1 above such that, in a case where the torque obtained from the force sensor becomes less than a threshold value, the control system executes a notification process to prompt an operator to replace the grinding wheel tool.

[0048] The design of aspect 2 allows the operator to recognize when it is time to change the disc tool.

[0049] A grinding machine according to aspect 3 of the present invention can be set up in aspect 2 above, further comprising an input device that enables the input of tool information, which includes outside diameter information of the disc tool and / or type information of the disc tool, wherein the threshold is a value that is set according to the tool information entered using the input device.

[0050] The design of aspect 3 allows for setting a replacement time that corresponds to the outer diameter information and / or the type information of the disc tool. This enables the disc tool to be replaced at a time that corresponds to the outer diameter and / or the type of disc tool.

[0051] A grinding machine according to aspect 4 of the present invention can be configured in any of the above aspects 1 to 3, further comprising: a drive motor configured to drive the rotating shaft; and an inverter configured to control a speed of the drive motor, wherein the control performs a speed control process of controlling the inverter based on the torque obtained from the force sensor, such that the speed of the drive motor becomes a target value corresponding to an outside diameter of the disc tool.

[0052] The design of aspect 4 enables the speed of the drive motor to be controlled according to the wear condition of the disc tool, which is detected using the torque obtained from the force sensor. This makes it possible to keep the peripheral speed of the disc tool constant.

[0053] A robot according to aspect 5 of the present invention is a robot comprising the grinding machine according to any one of aspects 1 to 4, which may be configured such that the control is a device configured to control the operation of the robot, and the control can perform an exchange process of causing the robot to exchange the disc tool, based on the detection of the worn condition of the disc tool.

[0054] According to the design of aspect 5, if the controller detects that the disc tool has worn down to the point where replacement is necessary, the controller causes the robot to automatically replace the disc tool. This reduces the operator's working time by the amount required to replace the disc tool.

[0055] The present invention is not limited to the embodiments mentioned, but can be modified by a person skilled in the art within the scope of the claims. The present invention also encompasses, within its technical scope, any embodiment derived by combining technical means disclosed in different embodiments. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2010-269396 [0002, 0003]

Claims

[1] Grinding machine, comprising: - a disc tool designed to rotate around a rotating shaft; - a force sensor configured to detect a torque around the rotating shaft, with the torque acting on the disc tool; and - a control system, - wherein the control system performs a detection process of recognizing a worn state of the disc tool based on the torque obtained from the force sensor. [2] Grinding machine according to claim 1, wherein in a case where the torque obtained from the force sensor becomes less than a threshold value, the control performs a notification process of executing a notification to prompt an operator to replace the disc tool. [3] Grinding machine according to claim 2, further comprising an input device that enables the input of tool information, which includes outside diameter information of the disc tool and / or type information of the disc tool, - where the threshold is a value set according to the tool information entered using the input device. [4] Grinding machine according to one of claims 1 to 3, further comprising: - a drive motor configured to drive the rotating shaft; and - a speed control device designed to control the speed of the drive motor, - wherein the control performs a speed control process of controlling the speed control device based on the torque obtained from the force sensor, so that the speed of the drive motor becomes a target value corresponding to an outer diameter of the disc tool. [5] Robot comprising the grinding machine according to claim 1, wherein the control is a device configured to control the operation of the robot, - wherein the control system performs an exchange process of causing the robot to exchange the disc tool, based on the detection of the worn condition of the disc tool.

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