Grinding system

Abstract

To provide a grinding system capable of increasing productivity while maintaining grinding quality.SOLUTION: A grinding system 1 comprises: a grinding tool 3 fitted to the tip of a manipulator to grind a weld bead; a laser sensor 4 that acquires surface shape data of the weld bead periphery on the rear side of the grinding tool 3 in the moving direction of the grinding tool 3 during grinding; a correction unit 52 that corrects a moving path of the grinding tool 3 on the basis of the surface shape data acquired by the laser sensor 4; a calculation unit 53 that calculates a grinding condition of the grinding tool 3 on the basis of the surface shape data; and a control unit 51 and a control unit 21 that cause the grinding tool 3 to grind the weld bead on the basis of the grinding path and the grinding condition of the grinding tool 3. The laser sensor 4 acquires the surface shape data before execution of the grinding work on the weld bead and during the execution of the grinding work on the weld bead.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a grinding system. [Background technology]

[0002] Patent Document 1 below discloses a system that determines the amount of grinding work based on three-dimensional data obtained by three-dimensional measurement of the periphery of a weld bead and then performs grinding.Patent Document 2 below also discloses a grinding system that grinds the same location on a workpiece multiple times along the same trajectory based on a torque command value that is the pressing reaction force of the grinding tool during grinding, and corrects the grinding point based on the difference between the torque command values ​​obtained in different repetitions, in order to prevent deterioration in grinding quality due to wear of the grinding wheel attached to the grinding tool. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-35307 [Patent Document 2] Patent No. 7294448 Summary of the Invention [Problem to be solved by the invention]

[0004] In grinding processes, the quality of the grinding process is generally evaluated based on the post-grinding finish. However, using a separate three-dimensional measuring device, as described in Patent Document 1, to inspect the post-grinding finish increases costs. Furthermore, such inspection of the finish is performed as a post-grinding process. Therefore, if the inspection results in poor grinding quality, other workpieces being ground in parallel during the inspection may also be of poor quality because they were ground under the same grinding conditions. To avoid this situation, it is possible to perform grinding operations while changing the grinding conditions, as described in Patent Document 2. However, even in this case, learning is not completed until the inspection is complete, and the machine must continue working under inappropriate grinding conditions or wait for the learning process to be completed, which reduces productivity.

[0005] Therefore, an object of the present invention is to provide a grinding system that can increase productivity while maintaining grinding quality. [Means for solving the problem]

[0006] A grinding system according to one aspect of the present invention includes a grinding tool attached to the tip of a manipulator for grinding a weld bead; a sensor unit that acquires surface shape data around the weld bead behind the grinding tool in the direction of movement of the grinding tool during grinding; a correction unit that corrects the movement path of the grinding tool based on the surface shape data acquired by the sensor unit; a calculation unit that calculates grinding conditions for the grinding tool based on the surface shape data acquired by the sensor unit; and a control unit that causes the grinding tool to grind the weld bead based on the movement path of the grinding tool corrected by the correction unit and the grinding conditions calculated by the calculation unit, wherein the sensor unit acquires the surface shape data before and during the grinding operation on the weld bead.

[0007] According to this aspect, surface shape data of the area around the weld bead is acquired behind the grinding tool before and during the grinding operation, and based on the surface shape data, the movement path of the grinding tool is corrected and the grinding conditions for the grinding tool are calculated, and the grinding tool is caused to grind the weld bead based on the corrected movement path and the calculated grinding conditions.

[0008] This allows the worker to proceed with the grinding work while evaluating the grinding condition based on the surface shape data around the weld bead obtained behind the grinding tool before and during the grinding work.

[0009] In the above aspect, the correction unit may calculate a correction amount for the movement path of the grinding tool based on the difference between a reference position of the weld bead that has been taught in advance and the position of the weld bead that is identified based on the surface shape data acquired by the sensor unit, and correct the movement path of the grinding tool by adding the calculated correction amount to the movement path of the grinding tool.

[0010] According to this aspect, the movement path of the grinding tool can be corrected according to the difference between the position of the weld bead identified by the acquired surface shape data around the weld bead and the taught reference position, thereby improving the accuracy of the grinding work.

[0011] In the above aspect, the grinding conditions may include a rotation speed of the grinding tool, a pressing force with which the grinding tool is pressed against the weld bead, and a moving speed of the grinding tool.

[0012] According to this aspect, it is possible to press the grinding portion of the grinding tool, which rotates at a set rotational speed, against the weld bead with a set pressing force while moving at a set moving speed.

[0013] In the above aspect, the calculation unit may calculate the grinding conditions using the volume of the grinding area to be ground from the weld bead, which is identified based on the surface shape data acquired by the sensor unit, and the grinding capacity of the grinding tool.

[0014] According to this aspect, grinding can be performed under grinding conditions calculated based on the grinding capacity of the grinding tool so that all of the grinding area of ​​the weld bead can be ground, thereby improving the accuracy of the grinding work.

[0015] In the above aspect, the calculation unit may calculate the grinding capacity of the grinding tool based on the grinding amount per unit time of the grinding tool and the degree of wear of a grinding part included in the grinding tool.

[0016] According to this aspect, when calculating the grinding capacity of the grinding tool, it is possible to take into account not only the grinding amount per unit time of the grinding tool but also the reduction in grinding amount due to the wear state of the grinding part.

[0017] In the above aspect, the calculation unit may calculate the degree of wear of the grinding part to be used when calculating the grinding capacity of the grinding tool for the next grinding operation based on the difference between the grinding amount determined using the surface shape data acquired by the sensor unit during the grinding operation of the weld bead and the grinding amount expected based on the grinding capacity of the grinding tool during the grinding operation.

[0018] According to this aspect, when calculating the grinding capacity for the next grinding, it is possible to use the degree of wear of the grinding part calculated based on the difference between the amount of grinding currently expected based on the grinding capacity of the grinding tool and the amount of grinding currently performed.

[0019] In the above aspect, the welding machine may further include a determination unit that determines a poor welding connection based on surface shape data acquired by the sensor unit during the grinding operation of the weld bead.

[0020] According to this aspect, it is possible to proceed with the grinding work while checking for the presence or absence of poor welding joints using the surface shape data around the weld bead acquired during the grinding work. [Effects of the Invention]

[0021] According to the present invention, it is possible to provide a grinding system that can increase productivity while maintaining grinding quality. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a diagram showing a schematic external configuration of a grinding system according to an embodiment; [Figure 2] FIG. 2 is a diagram illustrating a functional configuration of a grinding system according to an embodiment. [Figure 3] FIG. 10 is a schematic diagram showing how the surface shape around the weld bead is measured with a laser sensor while the weld bead is ground with a grinding tool. DETAILED DESCRIPTION OF THE INVENTION

[0023] A preferred embodiment of the present invention will be described with reference to the accompanying drawings. In each drawing, components with the same reference numerals have the same or similar configurations. Furthermore, since the drawings are schematic, the dimensions and proportions of each component may differ from those of the actual components.

[0024] [Grinding system configuration] Fig. 1 is a diagram illustrating a schematic external configuration of a grinding system 1 according to an embodiment. Fig. 2 is a diagram illustrating a functional configuration of the grinding system 1 according to an embodiment. Fig. 3 is a schematic diagram illustrating a state in which a laser sensor (sensor unit) 4 measures the surface shape around a weld bead WB while the weld bead WB is ground by a grinding tool 3.

[0025] The grinding system 1 includes, for example, a grinding tool control device 2, a grinding tool 3, a laser sensor 4, a robot control device 5, and a robot 6.

[0026] 2 is a control unit that controls the operation of the grinding tool 3. The grinding tool control device 2 has, as functional components, a control unit 21 and a storage unit 22, for example.

[0027] The control unit 21 is physically a processor, and controls the grinding operation by the grinding tool 3 based on the grinding conditions stored in the memory unit 22. The grinding conditions may include, for example, the rotation speed of the grinding tool 3, the pressing force with which the grinding tool 3 is pressed against the weld bead WB, and the movement speed of the grinding tool 3.

[0028] The grinding tool 3 is a tool that grinds a weld bead WB of a welded base metal PM. As shown in Fig. 3, the grinding tool 3 includes, for example, a spindle motor 31, a pressing control device 32, and a grinding unit 33.

[0029] Spindle motor 31 is a motor that rotates grinding unit 33. Pressing force control device 32 is a device that controls the pressing force that presses grinding unit 33 against weld bead WB. Grinding unit 33 is, for example, a grinding wheel, and is a member that grinds weld bead WB.

[0030] Laser sensor 4 is a sensor that irradiates a line of laser light LB and measures the surface shape of an object based on the reflected light. As shown in FIG. 3, laser sensor 4 is disposed behind grinding tool 3 in the grinding direction (the direction of movement during grinding). This allows laser sensor 4 to measure the surface shape around weld bead WB on the base metal PM behind grinding tool 3 as it moves over weld bead WB, and acquire surface shape data. Therefore, surface shape data around weld bead WB after grinding by grinding tool 3 can be acquired by laser sensor 4 while grinding is being performed by grinding tool 3.

[0031] In this embodiment, laser sensor 4 measures the surface shape around the weld bead WB both before grinding is performed on the weld bead WB and while grinding is being performed on the weld bead WB, and acquires surface shape data. In the measurement before grinding is performed, grinding tool 3 and laser sensor 4 are moved without grinding the weld bead WB, and the surface shape around the weld bead WB is measured.

[0032] 2 is a control unit that controls the operation of the robot 6. The robot control device 5 includes, as functional components, a control unit 51, a correction unit 52, a calculation unit 53, a determination unit 54, and a storage unit 55, for example.

[0033] The control unit 51 is physically a processor, and controls the operation of the robot 6 by executing a teaching program stored in the storage unit 55.

[0034] The robot 6 is an industrial robot, and includes an articulated arm (manipulator) mounted on a base member fixed to, for example, the floor of a factory. A grinding tool 3 and a laser sensor 4 are attached to the tip of the articulated arm. A welding torch, a robot hand, or the like can also be attached to the tip of the articulated arm depending on the work to be performed by the robot 6.

[0035] The control unit 51 of the robot control device 5 moves the grinding tool 3 attached to the tip of the articulated arm along a movement path that has been taught in advance, for example, in accordance with a teaching program that has been taught in advance.

[0036] Before performing the grinding operation, the worker instructs the robot 6 equipped with the grinding tool 3 on the movement path during the grinding operation. For example, the worker instructs the operation of the articulated arm so that the grinding part 33 of the grinding tool 3 moves along the longitudinal direction of the weld bead WB to be ground.

[0037] When grinding work is performed on the grinding portion 33 of the grinding tool 3, the abrasive of the grinding portion 33 is worn away. When the abrasive wears away, the amount of the weld bead WB ground away decreases according to the degree of wear. Therefore, it is preferable to correct the movement path of the grinding tool 3 and calculate the grinding conditions for the grinding tool 3 based on the degree of wear and the amount of grinding of the abrasive. Below, the correction of the movement path and the calculation of the grinding conditions will be described in order.

[0038] [Correction of movement path] The correction unit 52 of the robot control device 5 shown in Fig. 2 corrects the movement path of the grinding tool 3 based on the surface shape data acquired by the laser sensor 4. Before the first grinding operation, the surface shape data used is data acquired without grinding the weld bead, and before the second or subsequent grinding operation, the surface shape data used is data acquired during the previous grinding operation. An example of the procedure for correcting the movement path will be described below.

[0039] First, the correction unit 52 calculates the correction amount for the movement path of the grinding tool 3 based on the difference between a reference position, which is the position of the weld bead WB that has been taught in advance, and the position of the weld bead WB that is identified based on the surface shape data acquired by the laser sensor 4.

[0040] Next, the correction unit 52 corrects the movement path of the grinding tool 3 by adding the calculated correction amount to the current movement path of the grinding tool 3.

[0041] The control unit 51 of the robot control device 5 moves the grinding tool 3 attached to the tip of the articulated arm along the corrected movement path.

[0042] [Calculation of grinding conditions] 2 calculates grinding conditions for the grinding tool 3 based on the surface shape data acquired by the laser sensor 4. An example of a procedure for calculating the grinding conditions will be described below.

[0043] First, calculation unit 53 identifies the weld bead WB based on the surface shape data acquired by laser sensor 4 before the first grinding operation is performed, and calculates the volume of the grinding area that will be the area to be ground from the identified weld bead WB. Note that when performing the second or subsequent grinding operation, it is preferable to calculate the volume of the grinding area using the surface shape data acquired during the previous grinding operation.

[0044] Next, the calculation unit 53 calculates the grinding capacity of the grinding tool 3 by multiplying the grinding amount per unit time of the grinding tool 3 by the degree of wear of the grinding part 33, which will be described later.

[0045] Next, the calculation unit 53 calculates grinding conditions based on the calculated volume of the grinding region and the calculated grinding capacity of the grinding tool 3 so that the entire grinding region can be ground.

[0046] It is preferable to set the degree of wear when the first grinding operation is performed as 0%, and to calculate the degree of wear from the second time onwards according to the following procedure.

[0047] First, calculation unit 53 identifies the actual grinding amount, which is the amount of grinding removed from weld bead WB during the previous grinding operation, based on the surface shape data acquired by laser sensor 4 during the previous and previous-previous grinding operations. When performing a second grinding operation, it is preferable to use the surface shape data acquired before performing the first grinding operation as the surface shape data acquired during the previous-previous grinding operation.

[0048] Next, the calculation unit 53 identifies the expected grinding amount, which is the grinding amount expected based on the grinding capability of the grinding tool 3 during the previous grinding operation.

[0049] Next, the calculation unit 53 calculates the degree of wear of the grinding unit 33 based on the difference between the identified actual grinding amount and the identified expected grinding amount.

[0050] Here, as the difference between the actual grinding amount and the expected grinding amount increases, the degree of wear increases (increases from 0% at the initial stage), and the grinding ability of the grinding tool 3 decreases.

[0051] The control unit 21 of the grinding tool control device 2 operates the grinding tool 3 in accordance with the grinding conditions calculated by the calculation unit 53, and causes the grinding tool 3 to grind the weld bead WB.

[0052] [Determining welding joint defects] 2 determines whether there is a poor joint in the weld based on the surface shape data acquired by laser sensor 4 when grinding the weld bead WB. For example, when determining that there is a dent in the weld bead WB, determination unit 54 determines that there is a poor joint, and when determining that there is no dent in the weld bead WB, determination unit 54 determines that there is no poor joint.

[0053] By providing the judgment unit 54, it is possible to check the finish state after grinding with the grinding tool 3 based on the surface shape data acquired by the laser sensor 4 while grinding with the grinding tool 3.

[0054] As described above, according to the grinding system 1 of the embodiment, surface shape data of the area around the weld bead behind the grinding tool 3 is acquired before and during the grinding operation, and based on the surface shape data, the movement path of the grinding tool 3 is corrected and the grinding conditions by the grinding tool 3 are calculated, and the grinding tool 3 can be made to grind the weld bead based on the corrected movement path and the calculated grinding conditions.

[0055] This allows the worker to proceed with the grinding work while evaluating the grinding state based on the surface shape data around the weld bead WB acquired before and during the grinding work on the rear side of the grinding tool 3. Therefore, with the grinding system 1 according to the embodiment, the finish condition of the grinding work can be checked immediately after the grinding work, which makes it possible to improve productivity while maintaining grinding quality.

[0056] Furthermore, according to the grinding system 1 according to the embodiment, the movement path of the grinding tool 3 can be corrected using, as a correction amount, the difference between a previously taught reference position of the weld bead WB and the position of the weld bead WB identified based on the surface shape data acquired by the laser sensor 4. This makes it possible to improve the accuracy of the grinding operation.

[0057] Furthermore, according to the grinding system 1 according to the embodiment, when calculating the grinding capacity of the grinding tool 3, it is possible to take into account not only the grinding amount per unit time of the grinding tool 3 but also the reduced grinding amount due to the wear state of the grinding part 33. This makes it possible to improve the accuracy of the grinding work.

[0058] Furthermore, with the grinding system 1 according to the embodiment, the grinding operation can be carried out while checking for the presence or absence of welding joint defects using the surface shape data around the weld bead WB acquired during the grinding operation, thereby improving the accuracy of the grinding operation.

[0059] [Variations] It should be noted that the present invention is not limited to the above-described embodiment, and can be embodied in various other forms without departing from the spirit of the present invention. Therefore, the above-described embodiment is merely illustrative in all respects and should not be interpreted as being limiting.

[0060] For example, in the above-described embodiment, the grinding tool control device 2 controls the operation of the grinding tool 3, and the robot control device 5 controls the operation of the robot 6, but the grinding tool control device 2 and the robot control device 5 may be integrated into a single control device, and the integrated control device may control the operations of the grinding tool 3 and the robot 6 together. [Explanation of symbols]

[0061] 1... Grinding system, 2... Grinding tool control device, 3... Grinding tool, 4... Laser sensor, 5... Robot control device, 6... Robot, 21... Control unit, 22... Memory unit, 31... Spindle motor, 32... Pressing force control device, 33... Grinding unit, 51... Control unit, 52... Correction unit, 53... Calculation unit, 54... Determination unit, 55... Memory unit

Claims

1. a grinding tool attached to the tip of the manipulator and configured to grind the weld bead; a sensor unit that acquires surface shape data around the weld bead, the sensor unit being located behind the grinding tool in the direction of movement of the grinding tool during grinding; a correction unit that corrects a movement path of the grinding tool based on the surface shape data acquired by the sensor unit; a calculation unit that calculates grinding conditions for the grinding tool based on the surface shape data acquired by the sensor unit; a control unit that causes the grinding tool to grind the weld bead based on the movement path of the grinding tool corrected by the correction unit and the grinding conditions calculated by the calculation unit; and Equipped with the sensor unit acquires the surface shape data before performing a grinding operation on the weld bead and while performing a grinding operation on the weld bead. Grinding system.

2. the correction unit calculates a correction amount for the movement path of the grinding tool based on a difference between a reference position of the weld bead that is taught in advance and a position of the weld bead that is specified based on the surface shape data acquired by the sensor unit, and corrects the movement path of the grinding tool by adding the calculated correction amount to the movement path of the grinding tool. The grinding system of claim 1 .

3. the grinding conditions include a rotation speed of the grinding tool, a pressing force that presses the grinding tool against the weld bead, and a moving speed of the grinding tool. The grinding system of claim 1 .

4. the calculation unit calculates the grinding conditions using a volume of a grinding area to be ground from the weld bead, which is identified based on the surface shape data acquired by the sensor unit, and a grinding capacity of the grinding tool. The grinding system of claim 1 .

5. the calculation unit calculates the grinding capacity of the grinding tool based on the grinding amount per unit time of the grinding tool and the wear degree of a grinding part included in the grinding tool. The grinding system of claim 4.

6. the calculation unit calculates a wear degree of the grinding part to be used when calculating the grinding capacity of the grinding tool for the next grinding operation based on a difference between a grinding amount specified using the surface shape data acquired by the sensor unit during the grinding operation of the weld bead and a grinding amount expected based on the grinding capacity of the grinding tool during the current grinding operation. The grinding system of claim 5.

7. a determination unit that determines a welding joint defect based on the surface shape data acquired by the sensor unit during the grinding operation of the weld bead, The grinding system of claim 1 .

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