Tool position detection device and tool position detection system

Abstract

To provide a tool position detection device that allows the area around the device to be effectively utilized, can efficiently detect a deviation amount of a tool and is low cost.SOLUTION: A tool position detection device 3 comprises: a photoelectric sensor 7 capable of detecting a timing of interrupting an optical path L by a wire 10b of a welding torch 10; a support frame 8 that supports the photoelectric sensor 7; a rotary actuator 12 that rotates the support frame 8 forward and backward by 90° around a rotation axis C1 orthogonal to the optical path L; and a control unit 6 that controls the forward and backward rotation operations of the rotary actuator 12. The control unit 6 includes a deviation amount calculation section 6a that calculates a position deviation amount ΔS=V×Δt of the wire 10b on the basis of a movement speed V of the wire 10b and a difference Δt between a reference value t1 and an actual measured value t2 of the timing of interrupting the optical path L by the wire 10b.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a tool position detection device and a tool position detection system for detecting the position of a tool attached to the end of an arm of an industrial robot. [Background technology]

[0002] In recent years, many production lines in factories have been using a large number of industrial robots to efficiently carry out production. Various tools required for work are attached to the ends of the arms of these industrial robots, and productivity is increased by having them perform tasks repeatedly using these tools. However, a tool attached to an industrial robot such as the one described above may unexpectedly come into contact with a surrounding object during use, or may be deviated from a predetermined standard state due to maintenance or other reasons, which may cause subsequent production to be hindered.

[0003] To address this issue, devices that detect whether the position of a tool is deviated from a reference state are commonly known. For example, a tool position detection device disclosed in Patent Document 1 is capable of detecting the position of a tool attached to the end of an arm of an industrial robot, and includes two sets of photoelectric sensors each having a light-projecting unit that projects light and a light-receiving unit that receives the light projected from the light-projecting unit, and a support frame that supports the two sets of photoelectric sensors. The support frame is approximately U-shaped in plan view and is composed of a first frame extending horizontally and a pair of second frames extending horizontally in the same direction from each end of the first frame. The light-emitting unit of one photoelectric sensor is provided on the tip side of one second frame, while the light-receiving unit of one photoelectric sensor is provided on the base end side of the other second frame, and the light-emitting unit of the other photoelectric sensor is provided on the base end side of one second frame, while the light-receiving unit of the other photoelectric sensor is provided on the tip side of the other second frame, and a first optical path formed by the light projected by one photoelectric sensor and a second optical path formed by the light projected by the other photoelectric sensor intersect at a predetermined position. Each photoelectric sensor is capable of detecting the timing at which the tool interrupts the first optical path or the second optical path. After controlling the industrial robot so that the tool crosses and interrupts the first optical path and the second optical path, the difference between a reference value and an actual value for the timing at which the tool interrupts the first optical path or the second optical path is calculated to detect the amount of positional deviation of the tool from a reference position in two directions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent No. 1722935 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the tool position detection device of Patent Document 1, two sets of photoelectric sensors are arranged so that the first optical path and the second optical path intersect in a plan view, and therefore the support frame supporting each of the photoelectric sensors has a wide horizontal structure. This limits the area in which the tool can move around the device, restricting the operation of the industrial robot or making the teaching of tool operation complicated. Another problem is that two sets of photoelectric sensors are required to detect the amount of misalignment of the tool in two directions, which increases costs.

[0006] To avoid this, one possible method is to use a single photoelectric sensor and use an industrial robot to change the orientation of the tool relative to the optical path of the photoelectric sensor in two ways, crossing and blocking the optical path in each direction, thereby detecting the amount of positional deviation of the tool in two directions.

[0007] However, in the case of articulated industrial robots, which are often used on production lines, changing the tool orientation between two different positions requires complex rotation of the axes of all of the joints on the arm, which takes time to change the tool orientation and increases the time required to detect the amount of misalignment.

[0008] The present invention has been made in view of the above points, and an object of the present invention is to provide a low-cost tool position detection device and a tool position detection system including the same, which allows for wide and effective use of the space around the device, and is capable of efficiently detecting the amount of tool misalignment. [Means for solving the problem]

[0009] In order to achieve the above object, the present invention is characterized in that a mechanism is provided that can change the optical path of one photoelectric sensor in two directions.

[0010] Specifically, the target is a tool position detection device that detects the position of a tool attached to the end of an arm of an industrial robot, and the following measures have been taken.

[0011] That is, a tool position detection device according to a first aspect of the present invention comprises a photoelectric sensor configured to project light to form an optical path and capable of detecting the timing at which the optical path is blocked by the tool, a support frame that supports the photoelectric sensor, an optical path switching mechanism that can switch the direction of the optical path by rotating the support frame forward and backward at a predetermined angle around a rotation axis perpendicular to the optical path, and a control unit that is connected to the photoelectric sensor and the optical path switching mechanism and controls the forward and reverse rotation operation of the optical path switching mechanism, wherein the control unit is characterized by comprising a deviation amount calculation unit that calculates the amount of position deviation of the tool based on the moving speed of the tool and the difference between a reference value and an actual value of the timing at which the optical path is blocked by the tool. The tool position detection device configured in this way acts to consolidate the number of photoelectric sensors included in the device. It also acts to increase the area in which the tool can move around the device, thereby reducing restrictions on the operation of the industrial robot. Furthermore, the rotation of one axis of the optical path switching mechanism acts to change the orientation of the tool relative to the optical path of the photoelectric sensor.

[0012] A tool position detection device according to a second invention is the tool position detection device of the first invention, characterized in that the support frame includes a first frame extending horizontally and having the rotation axis extending vertically at the center, and a pair of second frames extending upward from each end of the first frame, and the photoelectric sensor includes a light-projecting unit provided on one of the second frames and projecting the light, and a light-receiving unit provided on the other second frame and receiving the light from the light-projecting unit, and the light-projecting unit and the light-receiving unit are opposite each other in the horizontal direction. The tool position detection device configured in this manner acts to make it easier for the tool to access the optical path of the photoelectric sensor not only from the side but also from above.

[0013] A tool position detection device according to a third aspect of the present invention is the tool position detection device of the second aspect, characterized in that a continuous hollow portion is formed inside the first frame and the second frame, and a communication hole that communicates with the hollow portion is formed in a lower central portion of the first frame, and a pair of signal lines are arranged in the hollow portion, one end of which is connected to the light-emitting unit and the light-receiving unit, and the other end of which is extended outside the first frame via the communication hole and connected to the control unit. The tool position detection device configured in this manner prevents the signal wires connected to the photoelectric sensor from being exposed around the device, and also functions so that the signal wires are gathered at the rotation center of the support frame and are routed to the outside of the support frame.

[0014] A tool position detection device according to a fourth invention is any one of the first to third inventions, wherein the optical path switching mechanism is a rotary actuator driven by compressed air supplied and exhausted via an electromagnetic valve. The tool position detection device configured in this manner functions to enable quick forward and reverse rotation of the support frame.

[0015] The present invention also targets a tool position detection system, and provides the following solution. That is, a tool position detection system according to a fifth aspect of the present invention comprises any one of the first to third tool position detection devices and the industrial robot connected to the control unit, wherein the control unit controls the optical path switching mechanism to rotate forward so that the optical path is in a first direction, and controls the industrial robot to move the tool horizontally from a predetermined first reference position at a constant speed, thereby causing the tool to block the optical path, and then controls the optical path switching mechanism to rotate in reverse so that the optical path is in a second direction different from the first direction, and controls the industrial robot to move the tool horizontally from a predetermined second reference position at a constant speed, thereby causing the tool to block the optical path, and the deviation amount calculation unit is configured to calculate a first position deviation amount of the tool when the optical path is in the first direction and a second position deviation amount of the tool when the optical path is in the second direction, respectively. The tool position detection system configured in this manner operates to detect the amount of deviation in two directions while minimizing the movement of the tool. [Effects of the Invention]

[0016] The tool position detection device of the first invention includes only one photoelectric sensor, resulting in a compact structure in a predetermined horizontal direction. This allows for more efficient use of the area around the device. Furthermore, the compact structure of the device in a predetermined horizontal direction increases the tool's movable area around the device. This reduces restrictions on the operation of the industrial robot and allows for more efficient teaching of tool operation. Furthermore, since only one photoelectric sensor is required for the device, the manufacturing cost of the device can be reduced. In addition, instead of changing the tool orientation relative to the optical path of the photoelectric sensor by rotating multiple axes of the industrial robot, the tool orientation relative to the optical path of the photoelectric sensor is changed by rotating a single axis of the optical path switching mechanism, thereby enabling detection of tool misalignment in two directions in a short time.

[0017] In the tool position detection device of the second invention, the tool can easily access the optical path of the photoelectric sensor not only from the side but also from above, which eliminates unnecessary movement in the tool operation controlled by the industrial robot when the tool crosses and blocks the optical path, making it possible to efficiently detect the amount of deviation of the tool in two directions.

[0018] In the tool position detection device of the third aspect of the invention, the signal wires connected to the photoelectric sensors are not exposed around the device, so that the signal wires connected to the photoelectric sensors can be prevented from coming into contact with objects around the device when the support frame is rotating. This prevents device failure due to signal wire breakage. Furthermore, because the signal wires are gathered at the rotation center of the support frame and extended outside the support frame, the two signal wires do not become intricately entangled when the support frame is rotating, and this reliably prevents signal wire breakage.

[0019] In the tool position detecting device of the fourth aspect of the invention, the support frame can be quickly rotated forward and backward, so that the amount of deviation of the tool in two directions can be detected efficiently.

[0020] The tool position detection system of the fifth aspect of the invention can detect misalignment in two directions while minimizing tool movement, thereby reliably reducing the time required for misalignment detection and enabling efficient tool misalignment detection work. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a perspective view showing a tool position detection system according to an embodiment of the present invention; [Figure 2] FIG. 2 is a view equivalent to FIG. 1, with the sensor unit rotated 90°. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] 10A and 10B are diagrams illustrating a method for detecting the amount of deviation of a tool and illustrating calculation formulas. [Figure 5]10 is a first half of a flowchart showing a procedure for detecting a deviation amount of a tool by a tool position detection system according to an embodiment of the present invention. [Figure 6] 10 is a second half of a flowchart showing a procedure for detecting the amount of deviation of a tool by the tool position detection system according to the embodiment of the present invention. [Figure 7] 6 is a perspective view showing a tool position detecting device according to an embodiment of the present invention, illustrating in detail the operation of the tool position detecting device carried out in steps S1 to S5 of FIG. 5. [Figure 8] 6 is a perspective view showing a tool position detecting device according to an embodiment of the present invention, and shows details of the operation of the tool position detecting device carried out in steps S6 to S8 of FIG. 5. FIG. [Figure 9] 7 is a perspective view showing a tool position detecting device according to an embodiment of the present invention, and shows details of the operation of the tool position detecting device performed in steps S9 to S13 in FIGS. 5 and 6. FIG. [Figure 10] 7 is a perspective view showing a tool position detecting device according to an embodiment of the present invention, illustrating in detail the operation of the tool position detecting device carried out in steps S14 to S18 of FIG. 6. FIG. [Figure 11] 7 is a perspective view showing a tool position detecting device according to an embodiment of the present invention, and shows details of the operation of the tool position detecting device carried out in steps S19 to S23 of FIG. 6. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description of the preferred embodiment of the present invention is merely exemplary in nature.

[0023] 1 and 2 show a tool position detection system 1 according to an embodiment of the present invention. This tool position detection system 1 is composed of a six-axis articulated industrial robot 2 having a welding torch 10 (tool) for arc welding attached to the end of its arm, and a tool position detection device 3 capable of detecting the position of a wire 10b being paid out from the end of a contact tip 10a attached to the welding torch 10.

[0024] The tool position detection device 3 includes a sensor unit 4 that is approximately U-shaped and opens upward when viewed from the side, a device main body 5 that supports the sensor unit 4, and a control unit 6 that is connected to the sensor unit 4 and the device main body 5.

[0025] As shown in Figures 1 to 3, the sensor unit 4 includes a photoelectric sensor 7 having a light-projecting portion 7a that projects light and a light-receiving portion 7b that receives the light projected from the light-projecting portion 7a, and a support frame 8 that supports the photoelectric sensor 7.

[0026] The support frame 8 comprises a first frame 8a extending horizontally and having a plate-like shape with some thickness, and a pair of second frames 8b extending upward from each end of the first frame 8a and having a plate-like shape with some thickness, and the central portion of the first frame 8a has a bow-shaped shape in plan view that protrudes on both sides in the horizontal direction perpendicular to the longitudinal direction of the first frame 8a.

[0027] As shown in Figure 3, the upper part (tip) of each second frame 8b has a groove portion 8c extending vertically, which opens continuously from the upper end surface to the outer surface, and on the opposing surfaces of the upper part of each second frame 8b, a light guide hole 8d communicating with the corresponding groove portion 8c is formed so as to extend along the direction in which both second frames 8b are arranged side by side.

[0028] The light-emitting portion 7a of the photoelectric sensor 7 is disposed in one groove portion 8c, while the light-receiving portion 7b of the photoelectric sensor 7 is disposed in the other groove portion 8c, with the light-emitting portion 7a and the light-receiving portion 7b arranged opposite each other in the horizontal direction.

[0029] The light projected from the light-projecting unit 7a passes through a light guide hole 8d formed in one of the second frames 8b, and then passes through a light guide hole 8d formed in the other of the second frames 8b to be received by the light-receiving unit 7b. That is, an optical path L is formed between the light-projecting unit 7a and the light-receiving unit 7b, and the photoelectric sensor 7 can detect the timing when the optical path L is interrupted by the wire 10b of the welding torch 10.

[0030] A hollow portion S1 is formed between the inside of the first frame 8a and the inside of each second frame 8b from the middle to the bottom.

[0031] A first communication hole 8e is formed in the upper part of each second frame 8b, connecting the groove portion 8c to the hollow portion S1, and a second communication hole 8f is formed in the lower center of the first frame 8a, connecting to the hollow portion S1.

[0032] A pair of signal lines 9 are arranged in the hollow section S1, one end of which is connected to the light-emitting section 7a and the light-receiving section 7b via each of the first communication holes 8e, and the other end of each signal line 9 is extended to the outside of the first frame 8a via the second communication hole 8f.

[0033] The device main body 5 comprises a main body case 11 having the shape of an approximately rectangular parallelepiped block extending horizontally, and a rotary actuator 12 (optical path switching mechanism) and an electromagnetic valve 13 housed in the internal space S2 of the main body case 11, with the rotary actuator 12 and the electromagnetic valve 13 being arranged in order from top to bottom in the internal space S2.

[0034] An upper surface through-hole 11a communicating with the internal space S2 is formed in the center of the top surface of the main body case 11. Furthermore, a side surface through-hole 11b communicating with the internal space S2 is formed in the approximate center of one longitudinal end surface of the main body case 11, and a rubber wiring hole cap 11c is fitted into the side surface through-hole 11b.

[0035] The rotary actuator 12 is driven by compressed air supplied and exhausted via an electromagnetic valve 13, and comprises a thick, plate-shaped actuator body 12a, and a disk-shaped rotary table 12b provided at the center of the upper surface of the actuator body 12a and rotatable around a rotation axis C1 extending vertically.

[0036] The rotary table 12b is disposed so as to face the outside of the actuator body 12a via the upper surface through-hole 11a, and the first frame 8a is fixed to the upper surface of the rotary table 12b so that the rotation axis C1 is located at the center of the first frame 8a.

[0037] The rotary actuator 12 is capable of rotating the rotary table 12b forward and backward at an angle of 90° around the rotation axis C1, and this rotational movement switches the support frame 8 between a first state in which the parallel arrangement direction of both second frames 8b coincides with the horizontal direction perpendicular to the longitudinal direction of the main body case 11, and a second state in which the parallel arrangement direction coincides with the longitudinal direction of the main body case 11, as shown in Figures 1 and 2, thereby switching the direction of the optical path L between the first direction d1 and the second direction d2, respectively.

[0038] As shown in FIG. 3, a central hole 12c that penetrates vertically is formed in the center of the actuator body 12a and the rotary table 12b, and the other ends of both signal lines 9 pass through the central hole 12c and the side through-hole 11b of the main body case 11 in that order, and are connected to the control unit 6 located outside the main body case 11.

[0039] The control unit 6 controls the forward and reverse rotation of the rotary actuator 12. As shown in Fig. 4, the control unit 6 is equipped with a deviation amount calculation unit 6a that calculates a positional deviation amount ΔS = V × Δt of the wire 10b based on the moving speed of the wire 10b, i.e., the moving speed V of the industrial robot 2, and the difference Δt between a reference value (time t1) and an actual measured value (time t2) of the timing at which the light path L is blocked by the wire 10b, and a display unit 6b that displays the results calculated by the deviation amount calculation unit 6a.

[0040] For example, as shown in Figure 4, after the wire 10b is moved to a predetermined position and measurement is started at the same time, the time t until the timing at which the light path L is blocked is t = 3 seconds when there is no positional misalignment of the wire 10b, but t = 3.2 seconds when there is a positional misalignment of the wire 10b.In this case, if the timing at which the wire 10b blocks the light path L is off by 0.2 seconds and the robot movement speed V is 20 mm / s, the positional misalignment amount ΔS is 20 × 0.2 = 4 mm.

[0041] For convenience, the longitudinal direction of the main body case 11 is defined as the X direction, the horizontal direction perpendicular to the longitudinal direction of the main body case 11 as the Y direction, and the vertical direction as the Z direction.

[0042] As shown in Figure 7, the control unit 6 controls the industrial robot 2 so that the tip of the wire 10b moves at a constant speed in the Z direction from a predetermined reference position P1 located on the rotation axis C1 to a reference position P2 located directly below this reference position P1, thereby blocking the light path L with the wire 10b.

[0043] At this time, the deviation amount calculation unit 6a calculates the amount of positional deviation H of the wire 10b in the up-down direction.

[0044] The control unit 6 controls the rotary actuator 12 to rotate in the forward direction so that the optical path L is in a first direction d1 along the Y direction, and controls the industrial robot 2 so that the wire 10b moves in the X direction from a predetermined reference position P3 (first reference position) at a constant speed as shown in FIG. 8, thereby blocking the optical path L with the wire 10b, or controls the industrial robot 2 so that the wire 10b moves in the X direction from a predetermined reference position P5 (first reference position) at a constant speed as shown in FIG. 9, thereby blocking the optical path L with the wire 10b, and then controls the industrial robot 2 to move in the X direction from a predetermined reference position P5 (first reference position) at a constant speed as shown in FIG. 10. As shown in FIG. 11, the rotary actuator 12 is reversely controlled so that the optical path L is in a second direction d2 along the X direction different from the first direction d1, and the industrial robot 2 is controlled so that the wire 10b moves in the Y direction from a predetermined reference position P8 (second reference position) at a constant speed, thereby blocking the optical path L with the wire 10b. Alternatively, as shown in FIG. 11, the industrial robot 2 is controlled so that the wire 10b moves in the Y direction from a predetermined reference position P10 (second reference position) at a constant speed, thereby blocking the optical path L with the wire 10b.

[0045] At this time, the deviation amount calculation unit 6a is configured to calculate a first positional deviation amount D1 (first positional deviation amount D1') of the wire 10b when the optical path L is in the first direction d1, and a second positional deviation amount D2 (first positional deviation amount D2') of the wire 10b when the optical path L is in the second direction d2.

[0046] Next, a detailed description will be given of a procedure for detecting the amount of misalignment in two directions of the wire 10b of the welding torch 10 by the tool position detection system 1. The misalignment detection operation is started in a state in which the control unit 6 controls the rotary actuator 12 to rotate forward so that the light path L is in the first direction d1.

[0047] As shown in FIG. 5, first, in step S1, the control unit 6 controls the industrial robot 2 to move the arm so that the tip of the wire 10b of the welding torch 10 reaches a position P1 located on the rotation axis C1 (see FIG. 7).

[0048] Next, in step S2, the control unit 6 controls the industrial robot 2 to start moving the arm along the Z direction so that the tip of the wire 10b of the welding torch 10 reaches position P2 located on the rotation axis C1, and receives a measurement start signal from the industrial robot 2, and proceeds to step S3.

[0049] In step S3, it is determined whether or not the optical path L is interrupted before the wire 10b reaches position P2, i.e., whether or not the control unit 6 has received an interruption timing signal from the photoelectric sensor 7. If the determination in step S3 is YES, i.e., if the wire 10b has interrupted the optical path L, the process proceeds to step S4, where the deviation amount calculation unit 6a calculates the positional deviation amount H in the Z direction, and then the process proceeds to step S5.

[0050] On the other hand, if the determination in step S3 is NO, that is, if the wire 10b does not block the light path L, it is determined that the position of the wire 10b is significantly deviated from the normal state, and the detection of the amount of deviation is terminated.

[0051] In step S5, the control unit 6 controls the industrial robot 2 to move the arm, thereby causing the tip of the wire 10b of the welding torch 10 to reach a position P3 that is significantly away from the optical path L to one side in the X direction, and then proceeds to step S6.

[0052] In step S6, the control unit 6 controls the industrial robot 2 to start moving the arm along the X direction so that the tip of the wire 10b of the welding torch 10 reaches position P4 located on the other side of the X direction, and then receives a measurement start signal from the industrial robot 2 and proceeds to step S7 (see FIG. 8).

[0053] In step S7, it is determined whether or not the optical path L is interrupted before the wire 10b reaches position P4, i.e., whether or not the control unit 6 has received an interruption timing signal from the photoelectric sensor 7. If the determination in step S7 is YES, i.e., if the wire 10b has interrupted the optical path L, the process proceeds to step S8, where the deviation amount calculation unit 6a calculates a first positional deviation amount D1 in the X direction on the base end side of the wire 10b, and then the process proceeds to step S9.

[0054] On the other hand, if the determination in step S7 is NO, that is, if the wire 10b does not block the light path L, it is determined that the position of the wire 10b is significantly deviated from the normal state, and the detection of the amount of deviation is terminated.

[0055] In step S9, the control unit 6 controls the industrial robot 2 to move the arm, thereby causing the tip of the wire 10b of the welding torch 10 to reach position P5, which is located directly above position P4 and spaced a predetermined distance from position P4, and then proceeds to step S10 (see Figure 9).

[0056] In step S10, the control unit 6 controls the industrial robot 2 to start moving the arm along the X direction so that the tip of the wire 10b of the welding torch 10 reaches position P6 located on one side of the X direction, and then receives a measurement start signal from the industrial robot 2 and proceeds to step S11.

[0057] In step S11, it is determined whether or not the optical path L is interrupted before the wire 10b reaches position P6, i.e., whether or not the control unit 6 has received an interruption timing signal from the photoelectric sensor 7. If the determination in step S11 is YES, i.e., if the wire 10b has interrupted the optical path L, the process proceeds to step S12, where the deviation amount calculation unit 6a calculates a first positional deviation amount D1' in the X direction on the tip side of the wire 10b, and then the process proceeds to step S13 as shown in FIG.

[0058] In step S13, the control unit 6 controls the industrial robot 2 to move the arm, thereby causing the tip of the wire 10b of the welding torch 10 to reach position P7, which is significantly away from the light path L to one side in the Y direction, and then proceeds to step S14.

[0059] In step S14, the industrial robot 2 outputs an optical path switching signal to the control unit 6. Then, the control unit 6 controls the rotary actuator 12 to rotate in the reverse direction so that the optical path L is switched to the second direction d2, and then the process proceeds to step S15 (see FIG. 10).

[0060] In step S15, it is determined whether the optical path L has switched to the second direction d2, i.e., whether the rotary table 12b of the rotary actuator 12 has rotated 90° backward. If the determination in step S15 is YES, i.e., if the optical path L has switched to the second direction d2, the process proceeds to step S16.

[0061] In step S16, the control unit 6 controls the industrial robot 2 to start moving the arm along the Y direction so that the tip of the wire 10b of the welding torch 10 reaches position P8 located on the other side of the Y direction, and receives a measurement start signal from the industrial robot 2, and proceeds to step S17.

[0062] In step S17, it is determined whether or not the optical path L is interrupted before the wire 10b reaches position P8, i.e., whether or not the control unit 6 has received an interruption timing signal from the photoelectric sensor 7. If the determination in step S17 is YES, i.e., if the wire 10b has interrupted the optical path L, the process proceeds to step S18, where the deviation amount calculation unit 6a calculates a second positional deviation amount D2 in the Y direction on the base end side of the wire 10b, and then the process proceeds to step S19.

[0063] On the other hand, if the determination in step S17 is NO, that is, if the wire 10b does not block the light path L, it is determined that the position of the wire 10b is significantly deviated from the normal state, and the detection of the amount of deviation is terminated.

[0064] In step S19, the control unit 6 controls the industrial robot 2 to move the arm, thereby causing the tip of the wire 10b of the welding torch 10 to reach position P9, which is located directly above position P8 and spaced a predetermined distance from position P8, and then proceeds to step S20 (see Figure 11).

[0065] In step S20, the control unit 6 controls the industrial robot 2 to start moving the arm along the Y direction so that the tip of the wire 10b of the welding torch 10 reaches position P10 located on one side of the Y direction, and receives a measurement start signal from the industrial robot 2, and proceeds to step S21.

[0066] In step S21, it is determined whether or not the optical path L is interrupted before the wire 10b reaches position P10, i.e., whether or not the control unit 6 has received an interruption timing signal from the photoelectric sensor 7. If the determination in step S21 is YES, i.e., if the wire 10b has interrupted the optical path L, the process proceeds to step S22, where the deviation amount calculation unit 6a calculates a second positional deviation amount D2' in the Y direction at the tip side of the wire 10b, and then the process proceeds to step S23.

[0067] On the other hand, if the determination in step S21 is NO, that is, if the wire 10b does not block the optical path L, it is determined that the position of the wire 10b is significantly deviated from the normal state, and the detection of the amount of deviation is terminated.

[0068] In step S23, the industrial robot 2 outputs an optical path switching signal to the control unit 6. Then, the control unit 6 rotates the rotary actuator 12 forward so that the optical path L is switched to the first direction d1, and returns the sensor unit 4 to its original position, thereby completing the misalignment amount detection operation.

[0069] As described above, according to the embodiment of the present invention, the tool position detecting device 3 includes only one photoelectric sensor 7, so that the tool position detecting device 3 has a compact structure in a predetermined horizontal direction. Therefore, the area around the tool position detecting device 3 can be used widely and effectively.

[0070] Furthermore, tool position detection device 3 has a compact structure in a predetermined horizontal direction, which increases the movable area of ​​wire 10b of welding torch 10 around tool position detection device 3. This reduces restrictions on the operation of industrial robot 2 and enables efficient teaching of the operation of wire 10b of welding torch 10.

[0071] Furthermore, only one photoelectric sensor 7 is required for tool position detection device 3, which reduces the manufacturing cost of tool position detection device 3. In addition, instead of changing the orientation of wire 10b of welding torch 10 with respect to optical path L of photoelectric sensor 7 by rotating multiple axes of industrial robot 2, the orientation of wire 10b of welding torch 10 with respect to optical path L of photoelectric sensor 7 is changed by rotating one axis of rotary actuator 12, so that the amount of misalignment of wire 10b of welding torch 10 in two directions can be detected in a short time.

[0072] Furthermore, because support frame 8 has a generally U-shape that opens upward in side view, wire 10b of welding torch 10 can easily access optical path L of photoelectric sensor 7 not only from the side but also from above. Therefore, when wire 10b of welding torch 10 crosses optical path L of photoelectric sensor 7 and breaks it, unnecessary movement can be eliminated in the movement of wire 10b of welding torch 10 controlled by industrial robot 2, and the amount of misalignment of wire 10b of welding torch 10 in two directions can be efficiently detected.

[0073] Furthermore, since the signal wire 9 connected to the photoelectric sensor 7 is not exposed around the tool position detection device 3, it is possible to prevent the signal wire 9 connected to the photoelectric sensor 7 from coming into contact with objects around the tool position detection device 3 when the support frame 8 is rotating. This makes it possible to prevent malfunctions of the tool position detection device 3 due to breakage of the signal wire 9. Furthermore, since the signal wires 9 are gathered at the rotation center of the support frame 8 and extended to the outside of the support frame 8, the two signal wires 9 do not become intricately entangled when the support frame 8 is rotating, and breakage of the signal wire 9 can be reliably prevented.

[0074] In addition, the optical path L is switched by a rotary actuator 12 driven by compressed air, which enables the support frame 8 to rotate quickly in both forward and reverse directions, thereby efficiently detecting the amount of misalignment of the wire 10b of the welding torch 10 in two directions.

[0075] Furthermore, because the direction of optical path L of photoelectric sensor 7 can be switched between two directions by rotary actuator 12, it becomes possible to detect the amount of misalignment in two directions while minimizing the movement of wire 10b of welding torch 10. Therefore, the time required for detecting the amount of misalignment can be reliably reduced, and the work of detecting the amount of misalignment of wire 10b of welding torch 10 can be performed efficiently.

[0076] In the embodiment of the present invention, the light-projecting unit 7a is arranged on one of the second frames 8b, while the light-receiving unit 7b is arranged on the other second frame 8b, thereby forming the optical path L; however, this is not limited to this. For example, it is also possible to arrange both the light-projecting unit 7a and the light-receiving unit 7b on one of the second frames 8b, while placing a reflector on the other second frame 8b, so that the light projected from the light-projecting unit 7a and reflected back by the reflector is received by the light-receiving unit 7b, thereby forming the optical path L between the two second frames 8b.

[0077] Furthermore, in the embodiment of the present invention, the sensor unit 4 is configured to rotate forward and backward by 90° around the rotation axis C1, but the rotation angle does not have to be 90°. For example, the sensor unit 4 may be configured to rotate forward and backward by 45° around the rotation axis C1, or may be configured to rotate forward and backward by 135°.

[0078] Furthermore, in the embodiment of the present invention, a rotary actuator 12 that operates by supplying or discharging compressed air is used to switch the direction of the optical path L, but this is not limited to this, and for example, a configuration in which forward and reverse rotation is performed by a motor with an encoder may also be used.

[0079] Furthermore, in the embodiment of the present invention, the sensor unit 4 is configured with a support frame 8 that is approximately U-shaped when viewed from the side, but this is not limited to this, and the sensor unit 4 may also be configured with a support frame 8 that is V-shaped when viewed from the side.

[0080] Furthermore, the tool position detection system 1 of the embodiment of the present invention detects the position of the wire 10b of the welding torch 10, but can also detect the position of other tools attached to the arm tip of the industrial robot 2. [Industrial Applicability]

[0081] The present invention is suitable for a tool position detection device that detects the position of a tool attached to the end of an arm of an industrial robot. [Explanation of symbols]

[0082] 1...Tool position detection system 2...Industrial robot 3...Tool position detection device 4...Sensor unit 5...Device body 6...Control unit 6a...Displacement amount calculation unit 6b...Display unit 7...Photoelectric sensor 7a...Light emitting unit 7b...Light receiving unit 8...Support frame 8a...First frame 8b...Second frame 8c...Groove portion 8d...Light guide hole 8e...First communication hole 8f...Second communication hole 9...Signal line 10...Welding torch 10a...Contact tip 10b...Wire 11...Body case 11a...Top surface through-hole 11b...Side surface through-hole 11c...Wiring hole cap 12...Rotary actuator (light path switching mechanism) 12a...Actuator body 12b...Rotary table 12c...Central hole 13...Solenoid valve d1...First direction d2...Second direction C1...Rotation axis D1, D1': First positional deviation amount D2, D2': Second positional deviation amount H: Positional deviation amount in Z direction L: Optical path S1: Hollow portion S2: Internal space V: Travel speed

Claims

1. A tool position detection device that detects the position of a tool attached to the end of an arm of an industrial robot, a photoelectric sensor configured to project light to form an optical path and capable of detecting a timing at which the optical path is interrupted by the tool; a support frame that supports the photoelectric sensor; an optical path switching mechanism that can switch the direction of the optical path by rotating the support frame forward and backward at a predetermined angle around a rotation axis that is perpendicular to the optical path; a control unit connected to the photoelectric sensor and the optical path switching mechanism and controlling the forward and reverse rotation operation of the optical path switching mechanism, The control unit is characterized in that it includes a deviation amount calculation unit that calculates the amount of position deviation of the tool based on the moving speed of the tool and the difference between a reference value and an actual value of the timing at which the tool blocks the optical path.

2. 2. The tool position detection device according to claim 1, the support frame includes a first frame extending horizontally and having the rotation axis extending vertically at the center, and a pair of second frames extending upward from each end of the first frame, the photoelectric sensor comprises a light-projecting unit provided on one of the second frames and projecting the light, and a light-receiving unit provided on the other second frame and receiving the light from the light-projecting unit, the light-projecting unit and the light-receiving unit facing each other in the horizontal direction.

3. 3. The tool position detection device according to claim 2, a continuous hollow portion is formed inside the first frame and the second frame, and a communication hole is formed in a central lower portion of the first frame, the communication hole communicating with the hollow portion; a pair of signal lines are arranged in the hollow portion, one end of the signal lines being connected to the light-emitting unit and the light-receiving unit, and the other end of the signal lines being brought out to the outside of the first frame through the communicating hole and connected to the control unit.

4. 4. The tool position detection device according to claim 1, The tool position detection device is characterized in that the optical path switching mechanism is a rotary actuator driven by compressed air supplied and exhausted via an electromagnetic valve.

5. 4. A tool position detection system comprising: the tool position detection device according to claim 1; and the industrial robot connected to the control unit, the control unit controls the optical path switching mechanism to rotate in a forward direction so that the optical path is in a first direction, and controls the industrial robot to move the tool at a constant speed in a horizontal direction from a predetermined first reference position, thereby blocking the optical path with the tool, and then controls the optical path switching mechanism to rotate in a reverse direction so that the optical path is in a second direction different from the first direction, and controls the industrial robot to move the tool at a constant speed in a horizontal direction from a predetermined second reference position, thereby blocking the optical path with the tool; The tool position detection system is characterized in that the deviation amount calculation unit is configured to calculate a first position deviation amount of the tool when the optical path is in the first direction and a second position deviation amount of the tool when the optical path is in the second direction.

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