Work assembly system, work assembly method, and work assembly quality inspection method

Abstract

This invention provides a workpiece assembly system, a workpiece assembly method, and a workpiece assembly quality inspection method that enable high-precision clamping of workpieces. [Solution] The system comprises a hinge gripping robot 2, a screw tightening robot 3, a tightening hole image sensor 4 that detects the three-dimensional coordinates of the tightening hole and the rotation angle of the heat-insulating box 10, a screw hole image sensor 5 that detects the three-dimensional coordinates of the screw hole, a driver bit detection sensor 6 that detects the two-dimensional coordinates of the driver bit attached to the screw tightening robot 3, and a control device 8 that controls the hinge gripping robot 2 and the screw tightening robot 3. The control device 8 controls the hinge gripping robot 2 and the screw tightening robot 3 so that the axial direction of the tightening hole detected by the tightening hole image sensor 4, the axial direction of the screw hole detected by the screw hole image sensor 5, and the axial direction of the driver bit detected by the driver bit detection sensor 6 are aligned in a straight line.

Description

Technical Field

[0001] The present invention relates to a work assembly system, a work assembly method, and a work assembly quality inspection method.

Background Art

[0002] Patent Document 1 describes using a system of a robot and an imaging device, arranging a driver on the arm of the robot, and automatically performing screw tightening in accordance with the captured image.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the system described in Patent Document 1 has a problem that it cannot tighten with high precision because it does not detect the postures of the thing to be screwed (the first object), the thing screwing (the second object), and the tightening tool (the driver).

Means for Solving the Problems

[0005] The present invention relates to a workpiece assembly system for assembling a workpiece having a screw hole through which a screw is inserted to a part to be assembled having a fastening hole formed to correspond to the screw hole, comprising: a workpiece gripping robot for gripping the workpiece; a screw fastening robot for fastening the screw; a first image sensor for detecting the three-dimensional coordinates of the fastening hole and the rotation angle of the part to be assembled; a second image sensor for detecting the three-dimensional coordinates of the screw hole; a driver bit detection sensor for detecting the two-dimensional coordinates of a driver bit attached to the screw fastening robot; and control means for controlling the workpiece gripping robot and the screw fastening robot, wherein the control means controls the workpiece gripping robot and the screw fastening robot so that the axial direction of the fastening hole detected by the first image sensor, the axial direction of the screw hole detected by the second image sensor, and the axial direction of the driver bit detected by the driver bit detection sensor are aligned in a straight line. [Brief explanation of the drawing]

[0006] [Figure 1] This is a top view showing a hinge assembly system according to an embodiment of the present invention. [Figure 2] This is a side view showing a hinge assembly system according to an embodiment of the present invention. [Figure 3] This is a perspective view showing an example of a refrigerator to which a hinge assembly system is applied. [Figure 4] This is a perspective view showing the state in which the fastening hole is detected by the image sensor for fastening holes. [Figure 5] This is a perspective view showing the state in which a screw hole is detected by a screw hole image sensor. [Figure 6] This is a perspective view of the driver bit detection sensor. [Figure 7] This is a perspective view showing the state just before tightening the screws. [Figure 8] Figure 7 is an enlarged view of the main part. [Figure 9] This is a diagram showing the layout of the image and laser displacement sensors. [Figure 10] This is a perspective view showing the hinge in its assembled state. [Figure 11] This is a side view showing the screw tightening state when a good result is obtained. [Figure 12A] This is a side view showing the screw tightening state when a negative result is detected. [Figure 12B] This diagram shows the case where there are multiple detection locations for screws. [Figure 12C] This diagram shows the case where there is only one screw detection position. [Figure 13] This is a side view showing the screw tightening state when a negative result is detected. [Figure 14] This is a computer block diagram that makes up the control system. [Modes for carrying out the invention]

[0007] Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 is a top view showing a workpiece assembly system according to an embodiment of the present invention, Figure 2 is a side view showing a hinge assembly system according to an embodiment of the present invention, and Figure 3 is a perspective view showing an example of a refrigerator to which the hinge assembly system according to an embodiment of the present invention is applied. As shown in Figures 1 and 2, the system comprises a hinge assembly system 1 (a system for performing a workpiece assembly system / workpiece assembly method), a hinge gripping robot 2, a screw tightening robot 3, a tightening hole image sensor 4 (first image sensor, see Figure 2), a screw hole image sensor 5 (second image sensor), a driver bit detection sensor 6 (see Figure 2), an image / laser displacement sensor 7 (see Figure 2), and a control device 8 (control means). In the following explanation, as shown in Figure 3, the case in which a hinge 50 (see Figure 5) supporting the lower side of the refrigerator compartment door 13 (rotating door) of a refrigerator 100 is fixed by screw tightening will be used as an example.

[0008] As shown in Figure 3, the refrigerator 100 is a device for storing food and other items at low temperatures, and has an opening at the front (front side in the illustration), and is equipped with an insulated box body 10 (refrigerator body) in which an insulating material such as vacuum insulation material or foamed urethane (not shown) is filled between a steel plate outer box 11 and a resin inner box 12. The insulated box body 10 is fitted with a rotating refrigerator door 13 (only the left side is shown by a dashed line) for opening and closing the upper refrigerator compartment 21, an ice maker compartment 22 located below the refrigerator compartment 21, a pull-out freezer door (not shown) for opening and closing the upper freezer compartment 23 and the lower freezer compartment 24, and a pull-out vegetable compartment door (not shown) for opening and closing the vegetable compartment 25 located at the bottom.

[0009] Furthermore, the insulated box body 10 is equipped with an insulating partition member 26 that insulates the refrigerator compartment 21, the ice-making compartment 22, and the upper freezer compartment 23. The insulating partition member 26 has fastening holes 27 into which a hinge 50 (see Figure 5) is attached by screw fastening.

[0010] Furthermore, although not shown in the diagram, the refrigerator 100 is equipped with a compressor, a heat exchanger (condenser), a capillary tube (throttling mechanism), and a cooler (evaporator). The refrigerant circulates sequentially through the compressor, heat exchanger, capillary tube, and cooler, and the air in the refrigerator compartment 21, ice maker compartment 22, upper freezer compartment 23, lower freezer compartment 24, and vegetable compartment 25 is cooled by heat exchange with the refrigerant flowing through the cooler.

[0011] A metal hinge 50 (see Figure 5) is provided at the bottom of the insulated box 10. This hinge 50 has a screw hole 51 (see Figure 5) through which a flanged screw 60 (see Figure 10) is inserted when the hinge is tightened. This screw hole 51 is formed to correspond to the aforementioned fastening hole 27.

[0012] Further, the hinge 50 (see FIG. 5) has a bracket 52a (see FIG. 7) fixed to the heat-insulating box body 10, a hinge shaft 52b (see FIG. 7) protruding upward from the bracket 52a, and a cam portion 52c (see FIG. 7) formed to protrude from the bracket 52a. In the refrigerator 100, since the refrigerator compartment doors 13 that open both to the left and right are provided, the hinges 50 are attached to both the left and right sides of the heat-insulating partition member 26. Note that the present invention is not limited to the refrigerator 100 provided with the refrigerator compartment doors 13 that open both to the left and right, and may be applied to a refrigerator provided with a refrigerator compartment door provided with a hinge on only one of the left and right sides, and can be appropriately changed according to the type of refrigerator.

[0013] Returning to FIG. 1, the hinge assembly system 1 includes a conveyor 9 that conveys the refrigerator 100 to the screw tightening position of the hinge 50. The heat-insulating box body 10 conveyed by the conveyor 9 is in a state where none of the refrigerator compartment doors 13 (see FIG. 3), the ice making compartment door, the upper freezer compartment door, the lower freezer compartment door, and the vegetable compartment door are attached. Further, hereinafter, the hinge 50 that supports the left refrigerator compartment door 13 (see FIG. 3) will be described as an example, and the description of the hinge that supports the right refrigerator compartment door will be omitted.

[0014] The hinge gripping robots 2 each have a gripping portion 71 (see FIG. 5) that grips the hinge 50, and a pair of them are provided on the left and right. The left hinge gripping robot 2 grips the hinge 50 that supports the left refrigerator compartment door 13 (see FIG. 3) from the supply position and moves it to a predetermined position.

[0015] The screw tightening robot 3 is an orthogonal robot disposed in front of the refrigerator 100 and having a driver bit 31 attached to its tip. Further, the screw tightening robot 3 fixes the hinge 50 to the heat-insulating box body 10 (refrigerator 100) by screw tightening the hinge 50 to the heat-insulating partition member 26. Note that the screw tightening robot 3 is not limited to an orthogonal robot, and may be applied to a vertical articulated robot or a horizontal articulated robot, and can be appropriately changed.

[0016] FIG. 4 is a perspective view showing a state where the tightening hole is detected by the tightening hole image sensor. As shown in Figure 4, the image sensor 4 for the fastening holes is configured to include an imaging unit 41 and an illumination unit 42. The image sensor 4 for the fastening holes illuminates the fastening holes 27 with the illumination unit 42, processes the image captured by the camera (imaging unit 41) to detect the three-dimensional position (three-dimensional coordinates X, Y, Z) of the fastening holes 27, and also detects the rotation angle θ (direction of rotation) of the insulated box 10. Note that the orientation of the refrigerator 100, which is transported by the conveyor belt 9, is not always constant, but flows with a certain degree of tilt. Therefore, the position of the fastening holes 27 is detected by considering not only the three-dimensional position of the fastening holes 27, but also the rotation angle θx around the X axis (see Figure 3), the rotation angle θy around the Y axis (see Figure 3), and the rotation angle θz around the Z axis (see Figure 3) of the refrigerator 100. Note that the rotation angle θx refers to the direction in which the insulated box 10 tilts forward or backward when viewed from the front. The rotation angle θy represents the direction in which the refrigerator 100 tilts to the left or right when viewed from the front. The rotation angle θz represents the direction in which the refrigerator 100 rotates around the vertical axis when viewed from above.

[0017] Figure 5 is a perspective view showing the detection of screw holes using an image sensor for screw holes. As shown in Figure 5, the screw hole image sensor 5 processes images captured by the camera to detect the three-dimensional position (three-dimensional coordinates X, Y, Z) of the screw hole 51 formed in the hinge 50. This detection is performed while the hinge 50 is being held by the hinge gripping robot 2. The hinge gripping robot 2 is also controlled so that the axial direction of the screw hole 51 of the hinge 50 faces the screw hole image sensor 5.

[0018] Figure 6 is a perspective view of the driver bit detection sensor. Note that the tip of the driver bit 31 is a consumable part and wears down daily. When it wears down too much, the bit needs to be replaced. This can lead to problems where the bit cannot be assembled in the same position. Therefore, a system is needed to detect the position of the driver bit tip.

[0019] As shown in Figure 6, the driver bit detection sensor 6 detects the two-dimensional position (two-dimensional coordinates) of the tip of the driver bit 31. The driver bit detection sensor 6 also includes an X-axis direction detection unit 6a and a Z-axis direction detection unit 6b. The X-axis direction detection unit 6a detects the position of the driver bit 31 in the X-axis direction and includes a light-emitting unit 6a1 at the top that emits light and a light-receiving unit 6a2 at the bottom that receives light. The Z-axis direction detection unit 6b detects the position of the driver bit 31 in the Z-axis direction and has a light-emitting unit 6b1 on one side in the left-right direction and a light-receiving unit 6b2 on the other side. In Figure 6, the line indicated by the code X1 shows the optical axis detected by the X-axis direction detection unit 6a, and the line indicated by the code Z1 shows the optical axis detected by the Z-axis direction detection unit 6b.

[0020] As shown in Figure 6, the position (coordinates) of the driver bit 31 in the X direction is detected when the tip of the driver bit 31 coincides with the optical axis X1 and the light is blocked. Then, the position (coordinates) of the driver bit 31 in the Z direction is detected when the tip of the driver bit 31 coincides with the optical axis Z1 and the light is blocked. Note that the driver bit detection sensor 6 is not limited to the system described in Figure 6, and position detection using an image sensor may also be applied, and can be changed as appropriate.

[0021] As shown in Figure 14 below, the control device 8 is composed of a computer equipped with a CPU (Central Processing Unit), memory, interface circuits, etc., and controls the hinge gripping robot 2 and the screw tightening robot 3 according to the control program stored in the memory (ROM). The control device 8 also acquires three-dimensional coordinates (X,Y,Z) and rotation angle θ from the image sensor 4 for the tightening hole, three-dimensional coordinates (X,Y,Z) from the image sensor 5 for the screw hole, and two-dimensional coordinates (X,Z) from the driver bit detection sensor 6.

[0022] Figure 7 is a perspective view showing the state immediately before tightening the screws. As shown in Figure 7, the hinge gripping robot 2 is controlled so that the screw hole 51 of the hinge 50 is positioned in front of the fastening hole 27 of the refrigerator 100 (in the negative Y direction), and the screw tightening robot 3 is controlled so that the driver bit 31 is positioned in front of the hinge 50 (in the negative Y direction).

[0023] Figure 8 is an enlarged view of the main part of Figure 7. As shown in Figure 8, the three axes—the axial direction of the fastening hole 27, the axial direction of the screw hole 51, and the axial direction of the driver bit 31—are aligned. In other words, the three axes—the axial direction of the fastening hole 27, the axial direction of the screw hole 51, and the axial direction of the driver bit 31—are corrected to be in a straight line. Although not shown, a flanged screw 60 is supplied to the tip of the driver bit 31. Then, the screw tightening robot 3 operates, inserting the flanged screw 60 into the screw hole 51 of the hinge 50 and screwing it into the fastening hole 27, thereby fixing the hinge 50 to the heat insulating partition member 26 (heat insulating box body 10). After the hinge 50 is fixed, the driver bit 31 retracts in the negative Y direction, and the hinge gripping robot 2 releases its grip on the hinge 50. Although not explained here, the other screw hole 51 formed in the hinge 50 is also assembled by screwing in the same manner as described above.

[0024] As described above, this embodiment is a hinge assembly system 1 for screwing a hinge 50 (workpiece) to an insulated box body 10 (assembly part), wherein the insulated box body 10 has a fastening hole 27 into which the hinge 50 is assembled, and the hinge 50 has a screw hole 51 through which a flanged screw 60 is inserted. Furthermore, the hinge assembly system 1 includes a hinge gripping robot 2 (workpiece gripping robot) that grips the hinge 50, a screw tightening robot 3 that tightens the flanged screw 60, a tightening hole image sensor 4 (first image sensor) that detects the three-dimensional coordinates (X,Y,Z) of the tightening hole 27 and the rotation angle θ of the heat-insulating box 10, a screw hole image sensor 5 (second image sensor) that detects the three-dimensional coordinates (X,Y,Z) of the screw hole 51, a driver bit detection sensor 6 that detects the two-dimensional coordinates (X,Z) of the driver bit 31, and a control device 8 (control means) that controls the hinge gripping robot 2 and the screw tightening robot 3. The control device 8 controls the axial direction of the tightening hole 27 detected by the tightening hole image sensor 4, the axial direction of the screw hole 51 detected by the screw hole image sensor 5, and the axial direction of the driver bit 31 detected by the driver bit detection sensor 6 to be aligned in a straight line (see Figure 8). This significantly improves the accuracy of screw tightening.

[0025] Furthermore, in this embodiment, the part to be assembled is the insulated box body 10 of the refrigerator 100, and the workpiece is a hinge 50 that supports the refrigerator door 13 for opening and closing the refrigerator compartment 21 (storage compartment) of the refrigerator 100. The hinge 50 is screwed through a screw hole 51 into a fastening hole 27 formed in the insulated box body 10 (see Figures 3 and 7). This makes it possible to attach hinges to the refrigerator 100 that require high screw fastening precision.

[0026] Furthermore, in this embodiment, the rotation angle θ includes the rotation angle θx around the X-axis in the left-right direction of the insulated box 10, the rotation angle θy around the Y-axis in the front-back direction of the insulated box 10, and the rotation angle θz around the Z-axis in the up-down direction of the insulated box 10 (see Figure 7). With this, by considering the rotation angles θx, θy, and θz of the insulated box 10, it becomes possible to screw the hinge 50 to the insulated box 10 with precision.

[0027] Next, the inspection method for the hinge 50 assembled to the insulated box 10 will be described. The items to be inspected are the presence or absence of the hinge 50 as the target part, the presence or absence of the flanged screw 60, and any looseness of the flanged screw 60. Figure 9 is a layout diagram of the image / laser displacement sensor, and Figure 10 is a perspective view showing the hinge in a screwed-down state. The screw used when screwing down the hinge 50 is the flanged screw 60. As shown in Figure 9, the hinge assembly system 1 is equipped with an image / laser displacement sensor 7. This image / laser displacement sensor 7 is a combination of an image sensor and a laser displacement sensor and is positioned lower than the height of the hinge 50, which is assembled by flanged screws 60. The image / laser displacement sensor 7 is also connected to a control device 8, and the image information detected by the image sensor and the position information detected by the laser displacement sensor are sent to the control device 8.

[0028] As shown in Figure 10, the image sensor of the image / laser displacement sensor 7 captures images and detects the positions S1 of the fastening hole 27, S2 of the hinge 50, and S3 of the flange of the flanged screw 60. Position S1 is the surface (reference surface M1) to which the back surface (back) of the hinge 50 makes contact. Position S2 is the surface (screw hole surface M2) on which the flanged screw 60 sits. Position S3 is the surface (flange surface) of the flange of the flanged screw 60. Note that the positions S1 and S2 indicated by circles in Figure 10 are not actual positions, but indicate points that the sensor observes. The laser displacement sensor of the image / laser displacement sensor 7 then measures the distance (height) from position S1 of the fastening hole 27 to position S2 (hinge surface) of the hinge 50 and the distance (height) from position S3 (flange surface) of the flanged screw 60, respectively. In this way, it is determined whether the tightening of the flanged screw 60 is good (OK) or bad (NG).

[0029] Figure 11 is a side view showing the screw tightening state when a good result is obtained. As shown in Figure 11, when the front of the refrigerator 100 (the front of the insulating partition member 26) is used as the reference plane M1, the determination is made based on the distance (height H1) from this reference plane M1 to the flange surface M3 of the flanged screw 60. If this distance (height H1) is a preset value (thickness of hinge 50 + thickness of flange 60a), the inspection is determined to be successful.

[0030] Figure 12A is a side view showing the screw tightening state when a negative result is detected, Figure 12B shows the case where there are multiple screw detection positions, and Figure 12C shows the case where there is a single screw detection position. As shown in Figure 12A, if screw loosening occurs, the distance from the reference surface M1 (height H10) will significantly exceed the value (predetermined value) which is the sum of the thickness of the hinge 50 and the thickness of the flange 60a. Also, as shown in Figure 12B, if the heights of three points P1, P2, and P3 are detected relative to the flange 60a, the inclination of the flanged screw 60 can also be detected. These three points are the lower center end (center lower end) and both ends in the left and right directions of the flange 60a when the flanged screw 60 is viewed from the front. Note that Figure 12A shows two points, P1 and P2, when viewed from the side. Incidentally, as shown in Figure 12C, if only one point at the bottom end of the flanged screw 60 is measured, the inclination of the flanged screw 60 may not be detected depending on the direction of the inclination, and a "NG" (Not Good) will be judged as a normal product. Note that Figure 12C shows the case where only the lower center end of the flange 60a is detected, and a "NG" is judged as a normal product.

[0031] Figure 13 is a side view showing the screw tightening state when the result is negative. As shown in Figure 13, if the hinge 50 is not installed and the flanged screw 60 is directly attached to the fastening hole 27 of the refrigerator 100, the height of the flange surface M3 relative to the reference surface M1 will be significantly lower (smaller than the predetermined value) than in the case of a good judgment (see Figure 11), so the judgment will be negative (NG). Note that in Figure 13, the screw hole surface M2 is shown with a dashed line together with the reference surface M1.

[0032] As described above, this embodiment provides a hinge assembly quality inspection method (work assembly quality inspection method) after screwing the hinge 50 into the insulated box body 10 of the refrigerator 100. Using the surface of the fastening hole 27 formed in the insulated box body 10 as a reference (reference surface M1), the height of the surface of the screw hole 51 formed in the hinge 50 (screw hole surface M2) and the height of the flange surface M3 of the flanged screw 60 are measured, respectively, to detect the presence or absence of the hinge 50, the presence or absence of the flanged screw 60, and any looseness of the flanged screw 60, thereby determining the quality of the hinge assembly (work assembly). With this method, if a product is determined to be defective, it can be removed from the production line, making it possible to prevent defective products from being passed on to subsequent processes.

[0033] Furthermore, in this embodiment, the height of the surface of the screw hole 51 (screw hole surface M2) and the height of the flange surface M3 of the flanged screw 60 are detected by an image / laser displacement sensor 7 equipped with an image sensor and a laser displacement sensor (see Figure 9). This allows for the detection of the position and height of the flanged screw 60, enabling accurate determination of the quality of the hinge assembly.

[0034] Furthermore, in this embodiment, if the height H1 (distance) from the reference surface M1, which is the surface of the fastening hole 27, to the flange surface M3 of the flanged screw 60 is a predetermined value obtained by adding the thickness of the hinge 50 to the thickness of the flange 60a, it is determined to be good (good) (see Figure 11). According to this, it can be determined that it is a normal product.

[0035] Furthermore, in this embodiment, the height is measured at three points on the flange surface: the left and right ends (P2, P3) and the central lower end (P1) (see Figure 12B). This allows for the detection of the inclination of the flanged screw 60 and reliable determination of screw loosening.

[0036] Furthermore, in this embodiment, if the height H10 from the reference surface M1, which is the surface of the fastening hole 27, to the flange surface M3 of the flanged screw 60 exceeds a predetermined value (a predetermined value for a normal product), it is determined to be a screw loosening and is therefore judged as NG (not good) (see Figure 12A). This allows for the determination of an NG product, and prevents NG products from being sent to subsequent processes.

[0037] Furthermore, in this embodiment, if the height from the reference surface M1, which is the surface of the fastening hole 27, to the flange surface M3 of the flanged screw 60 is lower than a predetermined value, the hinge 50 is deemed not to be assembled and is judged as NG. This allows for the identification of an NG product, preventing it from being sent to the next process.

[0038] Figure 14 is a computer block diagram that constitutes the control unit. The control device 8 is comprised of the computer 980 shown in Figure 14.

[0039] In Figure 14, the computer 980 constituting the control device 8 includes a CPU 981, a storage unit 982, a communication port 983, an input / output port 984, and a media port 985. Here, the storage unit 982 includes a RAM 982a, a ROM 982b, and an SSD (Solid State Drive) 982c.

[0040] The communication port 983 is connected to the communication circuit 986. The input / output port 984 is connected to the input / output device 987. The media port 985 reads and writes data to the recording medium 988. The ROM 982b stores the IPL (Initial Program Loader) and other programs executed by the CPU. The SSD 982c stores application programs and various data. The CPU 981 implements various functions by executing application programs and other data read from the SSD 982c into the RAM 982a.

[0041] It should be noted that the present invention is not limited to the embodiments described above, and various modifications and applications are also included within the scope of the technical concept of the present invention. For example, in this embodiment, a hinge attached to a refrigerator 100 was used as an example of the workpiece, but it is not limited to hinges and can be effectively used for anything that requires screw tightening precision. Also, in this embodiment, a flanged screw 60 was used as an example, but a screw without a flange and a washer may be used to fasten the hinge 50 to the insulated box 10. Furthermore, although the part to be assembled was described as a refrigerator, it can also be applied to any storage or refrigeration facility, such as a warming cabinet. [Explanation of symbols]

[0042] 1. Hinge Assembly System (Workpiece Assembly System) 2. Hinge gripping robot 3. Screw tightening robot 4. Image sensor for fastening holes (first image sensor) 5. Image sensor for screw holes (second image sensor) 6 Driver Bit Detection Sensor 7 Image / Laser Displacement Sensor 8. Control device (control means) 9. Conveyor 10. Insulated box body (assembled part) 13. Refrigerator door (revolving door) 21. Refrigerated room (storage room) 26. Insulated partition members 27 tightening holes 31 driver bits 41 Imaging Unit 42 Lighting Section 50 Hinge (Workpiece) 51 screw holes 60 Flanged Screws 60a flange 100 Refrigerator θx, θy, θz: Rotation angles

Claims

1. A workpiece assembly system for assembling a workpiece having a screw hole through which a screw is inserted to an assembly part having a fastening hole formed to correspond to the screw hole by screw fastening, A workpiece gripping robot that grips the aforementioned workpiece, A screw tightening robot for tightening the aforementioned screws, A first image sensor detects the three-dimensional coordinates of the fastening hole and the rotation angle of the assembled part, A second image sensor detects the three-dimensional coordinates of the screw hole, A driver bit detection sensor for detecting the two-dimensional coordinates of a driver bit attached to the screw tightening robot, The system comprises control means for controlling the workpiece gripping robot and the screw tightening robot, The control means controls the workpiece gripping robot and the screw tightening robot so that the axial direction of the fastening hole detected by the first image sensor, the axial direction of the screw hole detected by the second image sensor, and the axial direction of the driver bit detected by the driver bit detection sensor are aligned in a straight line.

2. A workpiece assembly system according to claim 1, The part to be assembled is the insulated casing of a refrigerator. The workpiece is a hinge that supports a revolving door for opening and closing the storage compartment of the refrigerator. A workpiece assembly system in which the hinge is screwed through the screw hole into the fastening hole formed in the heat-insulating box body.

3. A workpiece assembly system according to claim 2, The rotation angle includes the rotation angle θx of the heat-insulating box body around the X-axis in the left-right direction, the rotation angle θy of the heat-insulating box body around the Y-axis in the front-rear direction, and the rotation angle θz of the heat-insulating box body around the Z-axis in the up-down direction, in a work assembly system.

4. A workpiece assembly method comprising assembling a workpiece having a screw hole through which a screw is inserted to a part to be assembled having a fastening hole formed to correspond to the screw hole, The first image sensor detects the three-dimensional coordinates of the fastening hole and the rotation angle of the part to be assembled, The second image sensor detects the three-dimensional coordinates of the screw hole, The steps include: detecting the two-dimensional coordinates of the driver bit attached to the screw tightening robot that tightens the screw using a driver bit detection sensor; The control means controls a workpiece gripping robot and a screw tightening robot that grip the workpiece so that the axial direction of the fastening hole detected by the first image sensor, the axial direction of the screw hole detected by the second image sensor, and the axial direction of the driver bit detected by the driver bit detection sensor are aligned in a straight line. A workpiece assembly method comprising the following.

5. A method for inspecting the quality of workpiece assembly after screwing the workpiece to the assembly part, A workpiece assembly quality inspection method that determines the quality of workpiece assembly by measuring the height from the surface of the fastening hole formed in the part to be assembled to the surface of the screw hole formed in the workpiece and the height from the flange surface of the flanged screw, respectively, to detect the presence or absence of the workpiece, the presence or absence of the flanged screw, and any looseness of the flanged screw.

6. A method for inspecting the quality of workpiece assembly according to claim 5, A workpiece assembly quality inspection method in which the height of the screw hole surface and the height of the flange surface are detected by an image sensor and a laser displacement sensor.

7. A method for inspecting the quality of workpiece assembly according to claim 5, A workpiece assembly quality inspection method in which the height from the reference surface, which is the surface of the fastening hole, to the flange surface is determined to be good when the height is a predetermined value obtained by adding the thickness of the workpiece to the thickness of the flange of the flanged screw.

8. A method for inspecting the quality of workpiece assembly according to claim 7, The aforementioned height is determined by measuring three points on the flange surface: the left and right ends and the lower center end.

9. A method for inspecting the quality of workpiece assembly according to claim 8, A workpiece assembly quality inspection method in which, if the height from the reference surface, which is the surface of the fastening hole, to the flange surface exceeds the predetermined value, the assembly is judged to be defective as a loose screw.

10. A method for inspecting the quality of workpiece assembly according to claim 7, A workpiece assembly quality inspection method in which, if the height from the reference surface, which is the surface of the fastening hole, to the flange surface is lower than the predetermined value, the workpiece is judged to be defective as not being assembled.

Images