How to remove the screws

Abstract

To provide a machine screw removal method which prevents a machine screw from being left in a female screw hole of an engagement part in machine screw removal work by robot to achieve reduction of the working time and increase of the efficiency.SOLUTION: A machine screw removal method includes: a machine screw loosening operation for rotating a machine screw 5 in a loosening direction in a state where a driving part 5b of the machine screw and a bit tip come into contact with each other to loose the machine screw and take out the machine screw from a female screw hole 3a of an engagement part 3; and a machine screw drawing operation for drawing the machine screw with a machine screw head 5a held by a collet chuck 41.SELECTED DRAWING: Figure 4A

Description

[Technical field]

[0001] The present invention relates to a screw removal method for removing a screw that has been tightened using a screw loosening tool held by a robot arm, in which the threads of the screw (e.g., male threads) become caught on the threads of the component being tightened (e.g., female threads) or the screw cannot be removed by simply turning it in the loosening direction and remains in the female threaded hole of the component being tightened. [Background technology]

[0002] The task of loosening and removing screws is a task that is frequently performed in assembly and disassembly work, and automation using robots is becoming more common in order to make the work more efficient and faster.

[0003] A common method for loosening screws using a robot is to have a screw loosening tool such as an electric screwdriver or air impact driver held by a robot arm, calculate position information from image information captured by an image recognition camera, or align the screw by teaching the screw's position information, and then rotate the screw in the loosening direction to loosen it.

[0004] Fig. 7A is a diagram showing a state in which a plate-like member 102 is fastened to a fixed part 103 by a screw 101 having a male thread portion 101c with a constant diameter. Fig. 7B is a diagram showing a state in which a driver 104 is inserted into a driving portion (e.g., a Phillips-shaped groove) 101b machined into the head 101a of the screw 101 and rotated in the loosening direction, causing the screw 101 to come out of the female thread 103b of the fixed part 103. Fig. 7C is a diagram showing a state in which the screw 101 has come out of the fixed part 103 and fallen over without being able to stand on its own, causing the screw 101 to come off.

[0005] In the case of a screw 101 having a constant diameter of the male thread portion 101c, the threads of the female thread 103b of the fixed portion 103 and the threads of the male thread portion 101c of the screw 101 remain engaged with each other until the screw 101 comes out of the fixed portion 103, so the screw 101 comes out only by the amount that it is rotated in the loosening direction.

[0006] 8A is a diagram showing a state in which plate-shaped member 102 is fastened to fixing portion 103 by tapping screw 105, the diameter of male thread portion 105c of which becomes smaller toward the tip. Tapping screw 105 is used to fasten a housing or an exterior cover made of a thin metal plate material.

[0007] 8B shows the state in which the driver 104 is inserted into the drive portion 105b of the tapping screw 105 and rotated in the loosening direction, causing the tapping screw 105 to come out of the fixed portion 103. At this time, in order to prevent the tip of the driver 104 from coming off the drive portion 105b of the tapping screw 105 and causing the tapping screw 105 to spin freely, it is necessary to rotate the driver 104 in the loosening direction while it is in close contact with the drive portion 105b of the tapping screw 105 by the pressing force 106.

[0008] The thread meshing portion 107 indicates a portion where the threads of the male thread portion 105c of the tapping screw 105 mesh with the threads of the female thread portion 103b of the fixing portion 3. Since there are a sufficient number of meshed threads in the initial stage of loosening, even if the tapping screw 105 is pressed with a pressing force 106, the tapping screw 105 will come out by rotating in the loosening direction, but as shown in Fig. 8C, the thread meshing portion 107 also decreases in proportion to the amount of the tapping screw 105 coming out. In addition, since the tapping screw 105 has a shape in which the diameter becomes smaller toward the tip, at a certain point, the force 108 that comes out due to the meshing of the threads becomes smaller than the pressing force 106 of the driver 104, and even if the tapping screw 105 is rotated in the loosening direction, the tapping screw 105 does not come out but is pushed back, causing it to spin freely.

[0009] 8C is a diagram showing a state in which the tapping screw 105 spins freely and cannot be removed, remaining in the female screw hole 103b of the fixed part 103. Even if the fastened state between the plate-shaped member 102 and the fixed part 103 is released, with the tapping screw 105 remaining in the female screw portion 103b of the fixed part 103, the plate-shaped member 102 and the fixed part 103 cannot be separated from each other.

[0010] When a human being performs an operation to separate members fastened by such a tapping screw 105, the human being can easily move on to the next operation by picking up the left-behind tapping screw 105 with his / her fingertips and removing it. However, when a robot is used to perform the operation, in order to remove the left-behind tapping screw 105, an additional operation is required to change to a tool capable of picking up the head 105a of the tapping screw 105 and continue the operation after capturing an image of the state of the tapping screw 105 with an image recognition camera and acquiring position information. In addition, when the head 105a of the tapping screw 105 is picked up and pulled out, even if the tapping screw 105 is pulled out linearly in the axial direction, the thread of the male screw portion 105c of the tapping screw 105 and the thread of the female screw portion 103b of the fixing portion 103 interfere with each other and become caught. Therefore, it is necessary to program a complex robot operation such as swinging the tapping screw 105 left and right and pushing and pulling it in the axial direction while holding it, which is an issue in reducing the operation time in automation.

[0011] Patent Document 1 describes a fixed member dismantling system that uses a robot and a camera to detect screws and automatically loosen them. However, this system was developed for screws 101 with a constant diameter of the male thread portion as explained in Fig. 7A, and does not have a solution to the problem of tapping screws 105 being left behind as shown in Fig. 8C. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Patent No. 6051501 Summary of the Invention [Problem to be solved by the invention]

[0013] Although it is possible to automate the screw removal work using a robot by applying the method described in Patent Document 1, in order to remove the tapping screw 105 remaining in the female screw hole, an additional process is required, such as replacing the tool held by the robot or having an operator remove it in a subsequent process, and therefore there remain challenges in reducing the work time in automation.

[0014] Therefore, an object of the present invention is to provide a screw removal method that enables a screw that has come loose to be grasped and pulled out without changing tools, shortens the time required for screw removal work using a robot, and enables labor savings and improved work efficiency when introducing robots. [Means for solving the problem]

[0015] That is, a screw removal method according to one aspect of the present invention includes the following steps: The tip of the bit is brought into contact with the driving portion of the head of the screw screwed into the female screw hole of the engagement portion, and the bit is rotated in a direction to loosen the screw, The head of the screw coming out of the female screw hole of the engagement portion is gripped by a collet chuck, With the driving portion of the head of the screw and the tip of the bit in contact with each other, the collet chuck is operated to loosen the screw held by the collet chuck, and the collet chuck is pulled out and removed from the female screw hole of the engagement portion. , In the screw removal method, The bit and the collet chuck are attached to the tip of a robot arm, and the head of the screw is held by the collet chuck. When pulling out the screw, the robot arm repeatedly swings the collet chuck in the direction in which the screw is pulled out and moves it forward and backward in the axial direction relative to the direction in which the screw is pulled out, thereby pulling out the screw. A screw removal method according to another aspect of the present invention includes the steps of: The tip of the bit is brought into contact with the driving portion of the head of the screw screwed into the female screw hole of the engagement portion, and the bit is rotated in a direction to loosen the screw, The head of the screw coming out of the female screw hole of the engagement portion is gripped by a collet chuck, A screw removal method, comprising the steps of: loosening the screw held by the collet chuck while the driving portion of the head of the screw and the tip of the bit are in contact with each other; and removing the screw held by the collet chuck from the female thread hole of the engagement portion. the bit and the collet chuck are attached to a tip of a robot arm, and the head of the screw is gripped by the collet chuck. When the screw is pulled out, a pull-out resistance force generated by the male thread of the screw and the female thread of the engagement portion getting caught is measured by a sensor; The robot arm repeats swinging and forward / backward movements of the tip in the direction of pulling out the screw within a range of resistance below a specified value, and pulls out the screw to a specified position. . Effect of the Invention

[0016] By using the screw removal method according to the above aspect of the present invention, it is possible to remove screws that are left partially loose in the female threads because the threads of the screws are caught and cannot be separated, even though there is no fastening force to fasten the members together, without replacing the robot hand. As a result, it is possible to shorten the screw removal work time, and to realize labor saving and improvement of work efficiency when introducing robots. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram of a screw removal mechanism according to an embodiment of the present invention. [Figure 2A] FIG. 1 is a diagram showing a collet chuck in an open state according to an embodiment of the present invention; [Figure 2B] FIG. 1 is a diagram showing a collet chuck in a closed state according to an embodiment of the present invention. [Diagram 3] FIG. 1 is a diagram of a screw removal device according to an embodiment of the present invention. [Figure 4A] FIG. 1 shows a state after bit alignment according to an embodiment of the present invention. [Figure 4B] FIG. 1 is a diagram showing a state in which a bit and a driving part of a tapping screw are in contact with each other in an embodiment of the present invention. [Figure 4C] FIG. 1 is a diagram showing a state in which a tapping screw is being loosened according to an embodiment of the present invention. [Figure 5A] FIG. 1 is a diagram showing a state in which a collet chuck is being advanced in an embodiment of the present invention. [Figure 5B] FIG. 1 is a diagram showing a state in which the collet chuck grips the head of a tapping screw in an embodiment of the present invention. [Figure 5C] FIG. 1 is a diagram showing a state in which a tapping screw is being pulled out in the embodiment of the present invention. [Figure 5D] FIG. 1 is a diagram showing a state in which the collet chuck releases the grip on the head of the tapping screw in the embodiment of the present invention. [Figure 6] Flowchart of a screw removal method according to an embodiment of the present invention [Figure 7A] Diagram of components fastened using screws with a constant diameter male thread [Figure 7B]Diagram of a screw with a constant diameter male thread being loosened [Figure 7C] Diagram of a screw with a constant diameter male thread that has been pulled out [Figure 8A] Diagram of parts fastened with tapping screws [Figure 8B] Diagram of tapping screws being loosened [Figure 8C] Diagram of the tapping screw left behind in the fixing part DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] FIG. 1 is a diagram of a screw removing mechanism 40 capable of carrying out a screw removing method according to an embodiment of the present invention.

[0020] The screw removal mechanism 40 is attached to the force sensor 21 attached to the tip of the robot arm 9 via a robot arm shock absorbing mechanism 10. As an example, the robot arm shock absorbing mechanism 10 includes a guide shaft 10a that guides the axial movement of the screw removal mechanism 40, and a spring 10b that is disposed around the guide shaft 10a and has an upper end fixed to the force sensor 21 and a lower end fixed to a screw removal mechanism connecting member 11 described below.

[0021] The screw removing mechanism 40 includes at least a screw rotation drive device for rotating the screw 5, such as an air impact driver 12, a bit 13, a collet chuck 41, and an air cylinder 19 for the collet chuck.

[0022] More specifically, the upper end of the screw removal mechanism 40 is equipped with a screw removal mechanism connecting member 11, which is a plate-shaped member with an upside-down L-shaped side, and the upper surface of the horizontal plate of this screw removal mechanism connecting member 11 is connected to the spring 10b of the robot arm shock absorber mechanism 10.

[0023] The upper end of an air impact driver 12 is attached to the underside of the horizontal plate of the screw removal mechanism connecting member 11 as a tool for loosening the screws 5. In the embodiment of the present invention, an air impact driver 12 powered by compressed air is used as an example of a screw rotation drive device, but if it is necessary to finely adjust the rotation speed of the bit 13 when loosening, an electric driver powered by a servo motor may be used instead of the air impact driver 12.

[0024] The base end of a bit 13, for example, having a Phillips convex shape (i.e., a Phillips screwdriver shape) that matches the shape of the drive part 5b of the head 5a of the screw 5, is inserted into the lower end of the air impact driver 12. Since the bit 13 is subject to breakage during use or wear due to contact between the screw head 5a and the drive part 5b over long periods of use, it is desirable for the bit 13 to be attached in a way that allows it to be easily replaced relative to the tip of the air impact driver 12.

[0025] At the tip of the bit 13, a collet chuck 41 for gripping the head 5a of the screw 5 is provided, which comprises a collet 16 in the form of a conical tube member made up of multiple joined claw members and a flange body 15 in the form of a cylindrical member partially overlapping the outside of the collet 16, which are arranged coaxially around the periphery of the bit 13 and can move in the axial direction. The procedure by which the collet chuck 41 grips the head 5a of the screw 5 will be described later.

[0026] FIG. 2A is a diagram showing a collet chuck 41, which is composed of a flange body 15 and a collet 16, in an open state.

[0027] The flange body 15 has a central opening 15c on the upper surface of the bottom of the cylindrical member (e.g., the upper end surface in Figure 2A), through which the bit 13 passes so as to be able to move forward and backward in the axial direction, and on the inside of the tip opening edge (e.g., the lower end opening edge in Figure 2A), there is a ring-shaped protrusion 15b on which a conical inclined surface 15a is formed that narrows from the outer edge along the axial direction toward the inside.

[0028] The collet 16 is configured such that the bit 13 penetrates the center of a conical cylindrical member in a relatively movable manner in the axial direction. The conical cylindrical member is provided with a plurality of notches 16e in the radial direction with respect to the circumferential direction, and is divided into a plurality of claw members 16a in the circumferential direction (for example, three in FIG. 2A). At the inner tip (for example, the lower end in FIG. 2A) of each claw member 16a, there is a claw portion 16b that protrudes radially inward in a partially annular shape. The claw portions 16b have inner peripheral surfaces that are curved along the axial direction, and are arranged to face each other toward the center, so that they can grip the side of the head 5a of the screw 5, as described later. The outer peripheral surface of each claw member 16a has a conical inclined surface 16c on which the conical inclined surface 15a of the flange body 15 can slide and which approaches the center as it moves from the lower end to the upper end along the axial direction. A base end portion (eg, an upper end portion in FIG. 2A) of each of the claw members 16a is separated from the bit 13 so as not to come into contact with the bit 13, and each of the claw members 16a is movable axially relative to the bit 13.

[0029] A coil spring 14 for the flange body is disposed between the inner peripheral surface of the central opening 15c of the flange body 15 and the upper end of the claw member 16a of the collet 16, and around the bit 13. When the flange body 15 descends relative to the bit 13, a downward force is elastically applied to the collet 16 via the flange body spring 14.

[0030] Additionally, a coil spring for collet 17 is disposed around bit 13, between a ring-shaped stopper 18 near the tip of bit 13 and the upper end of claw member 16a of collet 16. When collet 16 descends relative to bit 13, collet spring 17 contracts, but when the downward force is no longer acting, the collet spring 17 is capable of returning to its original position by its biasing force.

[0031] In order to slide the collet 16 and flange body 15 coaxially with the bit 13 in the forward and backward directions relative to the screw 5, an air cylinder 19 for a collet chuck is installed on the outer surface of the vertical plate of the screw removal mechanism connecting member 11. That is, the air cylinder 19 for the collet chuck has a piston rod 19a whose tip is connected to the bottom of the upper end of the flange body 15 via a plate-shaped collet chuck connecting member 20, and in FIG. 1, when the piston rod 19a descends, the flange body 15 descends relative to the collet 16 and comes into contact with the collet 16, and the flange body 15 and the collet 16 also descend.

[0032] By moving the flange body 15 toward the tip end in the axial direction, i.e., by lowering it in Fig. 1, the notch 16e of the collet 16 closes toward the center, making it possible to firmly grip an object (such as a screw) inside the notch 16e. Fig. 2B is a diagram showing the collet chuck 41 in a closed state.

[0033] Fig. 3 is a diagram of a screw removal device 50 in an embodiment of the present invention. The screw removal device 50 includes the screw removal mechanism 40 described in Fig. 1 and a robot arm 9. The screw removal mechanism 40 is attached to the tip of the robot arm 9. A robot having vertical articulated joints is used as the robot arm 9 in order to remove the screws 5 arranged on the front, side, and top surface of the workpiece 23.

[0034] In addition, since the workpiece 23 is fixed onto the workpiece mounting table 24 having a rotation mechanism, by changing the orientation of the workpiece 23 so that the side with the screws 5 faces the robot arm 9, it is possible to remove the screws 5 on the right side, left side, and back.

[0035] When performing a screw loosening operation, it is necessary to align the center of the drive part 5b of the screw 5 with the center of the bit 13 of the screw removal mechanism 40. To do this, the workpiece 23 is rotated 90 degrees at a time, and the front, left and right side faces, back face, and top plane are each imaged by the screw position recognition camera 22. The screw position recognition camera 22 is disposed at the tip of the robot arm 9. The position of each screw 5 can be determined by the control unit 60 processing the coordinates of the screws 5 from the image information captured by the screw position recognition camera 22. For example, in the case where the workpiece 23 has a housing structure made of a thin sheet metal member, the rigidity of the housing decreases as the screws 5 are removed, and the shape of the housing changes due to the impact or vibration during removal, so that the position of the screw 5 may change from the position when it was imaged by the screw position recognition camera 22. For this reason, it is desirable to appropriately perform screw position confirmation imaging in accordance with the change in the shape of the housing (for example, at the timing before (just before) removing the screws on each side, or after the rotation operation when rotating the workpiece 23 by 90 degrees).

[0036] The control unit 60 is provided to control the screw removal operation, and controls the operation of the robot arm 9, the air cylinder 19 for the collet chuck, and the air impact driver 12 based on input information from the force sensor 21, the screw position recognition camera 22, the robot arm 9, the air impact driver 12, etc.

[0037] Next, the procedure for removing the screws will be described with reference to the drawings.

[0038] FIG. 4A is a diagram after the bit 13 and the driving part 5b of the tapping screw 5 are aligned in the embodiment of the present invention. FIG. 4A is a diagram showing a state in which a plate-shaped member 2 is fastened to a fixing part 3, which is an example of an engagement part of an object to be assembled or disassembled, by a tapping screw 5 in which the diameter of the male screw part 5c becomes smaller toward the tip. The tapping screw 5 is used, for example, to fix a housing or an exterior cover made of a thin metal plate material. Under the control of the control unit 60, the robot arm 9 is driven and controlled based on the image information captured by the screw position recognition camera 22 to match the center of the bit 13 with the center position of the driving part 5b of the tapping screw 5, and the bit 13 waits above the tapping screw 5. After that, the robot arm 9 is advanced (i.e., descended in FIG. 4A) to bring the tip of the bit 13 into contact with the driving part 5b of the tapping screw 5.

[0039] FIG. 4B is a diagram showing a state in which the tip of the bit 13 and the driving part 5b of the tapping screw 5 are in contact with each other in the embodiment of the present invention. FIG. 4C is a diagram showing a state in which the tapping screw 5 is being loosened in the embodiment of the present invention. When the tip of the bit 13 and the driving part 5b of the tapping screw 5 are in contact with each other, and air is supplied to the air impact driver 12 under the control of the control part 60 to rotate the bit 13 in a direction in which the tapping screw 5 is loosened, the tapping screw 5 comes out upward from the fixed part 3, which is an example of an engagement part, as shown in FIG. 4C. When the tapping screw 5 comes out, the entire screw removal mechanism 40 is pushed up, but the spring 10b of the robot arm buffer mechanism 10 is compressed by an amount equal to the pushing-up stroke, so that the robot arm 9 can hold the position before the screw 5 was loosened.

[0040] In the embodiment of the present invention, the spring 10b is used in the robot arm shock absorbing mechanism 10. However, instead of the spring 10b, an elastic body that generates a repulsive force while absorbing the upward stroke, such as a rubber material, may be used.

[0041] Next, the process of removing the tapping screw 5, which has come out of the fixed portion 3, from the female screw hole 3a of the fixed portion 3 will be described with reference to the drawings.

[0042] The tapping screw 5 will come out of the fixed part 3 when rotated in the loosening direction, but as mentioned above, if the force generating the force generating when the tapping screw 5 is loosened becomes smaller than the force that brings the bit 13 into close contact with the drive part 5b of the tapping screw 5 due to a reduction in the number of meshing threads between the male thread 5c of the tapping screw 5 and the female thread 3c of the fixed part 3, the screw 5 will not come out even when the tapping screw 5 is rotated in the loosening direction.

[0043] This state is detected by using the force sensor 21 installed between the robot arm 9 and the screw removal mechanism 40. The spring 10b of the robot arm shock absorber mechanism 10 is compressed in proportion to the amount of the tapping screw 5 that is removed, so the force sensor 21 detects the reaction force of the spring 10b, and the reaction force does not increase even though the bit 13 is rotating for a certain period of time. Alternatively, if the control unit 60 detects that the reaction force is decreasing as the tapping screw 5 is pushed back, the control unit 60 can determine that the tapping screw 5 is spinning freely without being removed.

[0044] When the control unit 60 detects such an idling state of the tapping screw 5, the air cylinder 19 for the collet chuck is driven under the control of the control unit 60 to move the collet chuck 41 forward (i.e., downward in FIG. 4C).

[0045] 5A is a diagram showing a state in which collet chuck 41 in the embodiment of the present invention is advanced (i.e., lowered in FIG. 5A). Cylinder rod 19a of collet chuck air cylinder 19 and flange body 15 are connected to collet chuck connecting member 20. In conjunction with the downward stroke of cylinder rod 19a of collet chuck air cylinder 19, flange body 15 descends toward tapping screw 5. Flange body 15 and collet 16 are separate parts, but flange body spring 14 incorporated inside flange body 15 is pressed by flange body 15, so that collet 16 also descends together with flange body 15.

[0046] When the collet 16 descends, the collet spring 17 built into the collet 16 is compressed in conjunction with the downward stroke of the collet 16. Because a stopper 18 is attached to the collet spring 17 near the tip of the bit 13, the collet spring 17 does not fall off the bit 13 when the collet 16 descends, and by holding the position of the downward end, the collet 16 stops at a predetermined downward position.

[0047] The lowering position of the collet 16 is adjusted by changing the thickness of the stopper 18 or the length of the collet spring 17 so that the collet 16 can be stopped in a position below the tip of the bit 13 and at a position where it can grip the head 5a of the tapping screw 5 when the collet 16 is closed.

[0048] When the collet 16 has been lowered to a position where it grips the head 5a of the tapping screw 5, the flange body 15 is further lowered, whereby the notch 16e of the collet 16 closes and the collet 16 grips the head 5a of the tapping screw 5.

[0049] 5B is a diagram showing a state in which collet chuck 41 in the embodiment of the present invention grips head 5a of tapping screw 5. Collet 16 grips head 5a of tapping screw 5 with drive portion 5b of tapping screw 5 and the tip of bit 13 in a state of tight contact. Therefore, even if there is a discrepancy in the timing at which each of multiple notches 16e of collet 16 closes to grip head 5a of tapping screw 5 with claw member 16a, tapping screw 5 can be securely gripped without causing a phenomenon such as flying off.

[0050] Next, while the head 5a of the tapping screw 5 is still held by the collet 16, the tip of the robot arm 9 is moved backward in the direction of removal (i.e., upward in FIG. 5B). At this time, the male thread 5c of the tapping screw 5 may get caught on the female thread 3c of the fixed part 3, or the male thread 5c of the tapping screw 5 may get caught on the plate-like member 2, and a catch resistance may be generated when the tapping screw 5 is pulled straight upward. If such a catch occurs, if the tip of the robot arm 9 is moved backward (i.e., upward in FIG. 5B) by force, the entire screw removal device may be overloaded and may report an error and stop, or the plate-like member 2 and the tapping screw 5 may be lifted together in a caught state, or the screw removal mechanism 40 may be damaged. For this reason, the force sensor 21 detects the pull-out resistance when the tip of the robot arm 9 is moved backward (i.e., moved upward in FIG. 5B), and if the control unit 60 detects that the pull-out resistance is equal to or greater than a specified value, the control unit 60 controls the robot arm 9 to temporarily stop moving backward (i.e., moving upward in FIG. 5B) the tip of the robot arm 9, under the control of the control unit 60, and moves backward (i.e., moved upward in FIG. 5B) while swinging the tip of the robot arm 9 left and right in small increments relative to the direction in which the screw 5 is pulled out. Alternatively, the robot arm 9 moves backward (i.e., moved upward in FIG. 5B) little by little while repeatedly pulling out and advancing (i.e., moving downward in FIG. 5B). In this case, the force sensor 21 continues to measure the pull-out resistance, and if the control unit 60 detects that the pull-out resistance tends to increase relative to the amount of pulling out, the left and right swinging and / or forward and backward movements (i.e., moving downward or upward in FIG. 5B) are further repeated, and the tapping screw 5 is pulled out while releasing the hook between the tapping screw 5 and the fixing part 3 or the plate-like member 2. FIG. 5C is a diagram showing a state in which the tapping screw 5 is being pulled out in the embodiment of the present invention.

[0051] Next, when the withdrawal of the tapping screw 5 is completed and the tip of the robot arm 9 can be returned to the standby position shown in Fig. 5D (an example of a predetermined position during the withdrawal operation), the collet chuck air cylinder 19 is operated to pull the flange body 15 back to its original position, which opens the notch 16e of the collet 16, releases the grip on the tapping screw 5, and the tapping screw 5 falls out, completing the removal of the tapping screw 5. Furthermore, by operating the collet chuck air cylinder 19 to pull the flange body 15 back, the compression of the collet spring 17 is released and the collet 16 is pushed back to its original position.

[0052] 5D is a diagram showing a state in which the collet chuck 41 in the embodiment of the present invention releases the grip of the head 5a of the tapping screw 5. It is assumed that in most cases, the tapping screw 5 falls downward as soon as the head 5a of the tapping screw 5 is released from the collet 16. However, if the tip of the bit 13 is worn unevenly or foreign matter adheres to the plus slot of the drive part 5b of the tapping screw 5, causing the tip of the bit 13 and the drive part 5b of the tapping screw 5 to be caught in each other, the tapping screw 5 will not fall off even if the collet 16 is released from the grip. In this way, if the tapping screw 5 remains attached to the tip of the bit 13, it is not possible to remove the tapping screw 5 at another position. Therefore, the vicinity of the tip of the bit 13 is imaged by the screw position recognition camera 22, and the control unit 60 checks whether or not there is a screw at the tip of the bit 13 by a known method such as pattern matching based on the image information from the screw position recognition camera 22. An example of pattern matching here is to determine the imaging position or angle, take an image in advance at that position with and without the screw, and compare that image data to determine whether or not there is a screw remaining. If the control unit 60 determines that there is a screw, the air impact driver 12 is operated under the control of the control unit 60 to rotate the bit 13 and shake off the tapping screw 5. An additional screw recovery operation is performed by placing a magnet for screw recovery (not shown) near the work setting table 24 and bringing the tapping screw 5 close to it and recovering it by magnetic attraction.

[0053] Next, the steps of the screw removal method according to the embodiment of the present invention will be described with reference to a flowchart.

[0054] 6 is a flowchart of a screw removing method according to an embodiment of the present invention. The screw removing method can be performed under the control of the control unit 60.

[0055] First, in step S1, the tip of the robot arm 9 is moved to move the screw position recognition camera 22 attached to the tip of the robot arm 9 to the opposing surface of the workpiece 23 to capture an image, and position information of the screw 5 is obtained.

[0056] Next, in step S2, the tip of the robot arm 9 is moved to align the center of the tip of the bit 13 inserted into the air impact driver 12 with the center of the drive portion 5b of the tapping screw 5.

[0057] Next, in step S3, the robot arm 9 is moved forward (i.e., lowered in FIG. 4A) to insert the tip of the bit 13 into the drive portion 5b of the tapping screw 5, and then the air impact driver 12 is operated to rotate the bit 13 for a predetermined time to loosen the tapping screw 5.

[0058] Next, in step S4, the vicinity of the tip of the bit 13 is imaged by the screw position recognition camera 22, and the control unit 60 confirms the presence or absence of a screw at the tip of the bit 13 by a known method such as pattern matching based on the image information from the screw position recognition camera 22. If a remaining screw is confirmed when checking for a remaining screw, an additional step such as changing the hand was required in the past. However, in the embodiment of the present invention, since the screw removal mechanism 40 having both the function of loosening the screw 5 and the function of pinching and pulling out the screw 5 is attached to the robot arm 9, the cylinder rod 19a of the collet chuck air cylinder 19 is lowered, and the collet 16 is advanced, i.e., lowered, together with the flange body 15, via the flange body spring 14 in order to grip the head 5a of the tapping screw 5 in step S5 without replacing the hand. As a result, the head 5a of the tapping screw 5 is gripped by the collet 16.

[0059] Next, in step S6, while the head 5a of the tapping screw 5 is still held by the collet 16, the operation of pulling out the screw 5 in step S7 is performed. The pull-out resistance force at this time is measured in real time by the force sensor 21. If the control unit 60 detects that the resistance force during the pull-out is equal to or less than the specified value X Newtons, the control unit 60 determines that the male thread 5c of the tapping screw 5 is not caught, and moves the robot arm 9 upward to the pull-out completion point in step S9. If the control unit 60 detects that the resistance force during the pull-out exceeds a specified value X Newtons, the control unit 60 determines that the male thread 5c of the tapping screw 5 is caught on the female thread 3c of the fixed part 3 of the workpiece 23 or the plate-like member 2, and under the control of the control unit 60, in step S8, the screw head 5a is held by the collet 16, and the screw removal mechanism 40 is swung left and right or advanced and retreated by the robot arm 9, or the bit 13 is rotated in a direction to loosen the screw 5, to perform the pull-out operation. In parallel with the amount of pull-out, the force sensor 21 continuously measures the pull-out resistance force, and if the control unit 60 determines that the pull-out resistance force has a tendency to increase, the pull-out operation is temporarily stopped under the control of the control unit 60, and the left and right swing and advanced and retreated movements are repeated in small increments to release the threads 3c, 5c from being caught by each other, and the pull-out operation is completed in step S9.

[0060] Then, in step S10, the control unit 60 checks whether any screws remain, as in step S4, and if there are no remaining screws, the control unit 60 determines that removal of the screws 5 is complete, and continues removing screws in other positions under the control of the control unit 60. If any remaining screws are confirmed in step S10, an error is issued in step S11 under the control of the control unit 60, an abnormality is detected, the screw removal device 50 is stopped, and measures such as the worker manually removing the screws 5 are taken.

[0061] According to the present invention, when removing screws using a robot, the threads 3c, 5c of the screw 5 get caught on each other and cannot be separated even though there is no fastening force to fasten the components together. Alternatively, it is possible to remove the screw 5 that is left partially loose in the female screw hole 3a without changing the hand of the robot arm 9, shortening the screw removal work time and realizing labor saving and improved work efficiency when introducing robots.

[0062] In addition, by appropriately combining any of the various embodiments or modifications described above, it is possible to achieve the effects of each of them. In addition, combinations of embodiments, combinations of examples, or combinations of embodiments and examples are possible, and combinations of features of different embodiments or examples are also possible. [Industrial Applicability]

[0063] The screw removal method according to the above aspect of the present invention is preferably used, for example, in a process of automatically dismantling housing covers, which are an example of objects to be dismantled, in the dismantling of collected discarded home appliances at home appliance recycling plants or the like. [Explanation of symbols]

[0064] 1 bis 2 Plate-shaped members 3 Fixed part 3c Female Thread 4 Driver 5 Tapping screws 5a head 5b Drive unit 5c male thread 6 Pressing force 7 Thread engagement 8. The Power to Come Out 9. Robot Arm 10 Robot arm shock absorber 10a Guide shaft 10b Spring 11 Screw removal mechanism connecting member 12 Air impact driver 13-bit 14 Spring for flange body 15 Flange body 15a Conical inclined surface 15b Center opening 16 Colette 16a Claw member 16b Claw part 16e Notch 17 Collet spring 18 Stopper 19 Air cylinder for collet chuck 19a Piston rod 20 Collet chuck connecting member 21 Force sensor 22 Screw position recognition camera 23 Work 24 Workpiece placement table 40 Screw removal mechanism 41 Collet chuck 50 Screw removal device

Claims

1. The tip of the bit is brought into contact with the driving portion of the head of the screw screwed into the female screw hole of the engagement portion, and the bit is rotated in a direction to loosen the screw, The head of the screw coming out of the female screw hole of the engagement portion is gripped by a collet chuck, A screw removal method, comprising the steps of: loosening the screw held by the collet chuck while the driving portion of the head of the screw and the tip of the bit are in contact with each other; and removing the screw held by the collet chuck from the female thread hole of the engagement portion. This screw removal method comprises the steps of: attaching the bit and the collet chuck to the tip of a robot arm; gripping the head of the screw with the collet chuck; and repeating a swinging motion of the collet chuck by the robot arm in the direction in which the screw is pulled out, and a forward and backward motion in the axial direction relative to the direction in which the screw is pulled out, to pull out the screw.

2. The tip of the bit is brought into contact with the driving portion of the head of the screw screwed into the female threaded hole of the engagement portion, and the bit is rotated in the direction to loosen the screw, The head of the screw coming out of the female screw hole of the engagement portion is gripped by a collet chuck, A screw removal method, comprising the steps of: loosening the screw held by the collet chuck while the driving portion of the head of the screw and the tip of the bit are in contact with each other; and removing the screw held by the collet chuck from the female thread hole of the engagement portion. the bit and the collet chuck are attached to a tip of a robot arm, and the head of the screw is gripped by the collet chuck. When the screw is pulled out, a pull-out resistance force generated by the male thread of the screw and the female thread of the engagement portion getting caught is measured by a sensor; A screw removal method comprising repeating swinging motion and forward and backward motion of the tip of the robot arm in the direction of pulling out the screw within a range of resistance force below a specified value, thereby pulling out the screw to a predetermined position.

3. a sensor is used to measure a pull-out resistance force generated when the male thread of the screw and the female thread of the engagement portion are caught when the screw is pulled out while the head of the screw is held by the collet chuck; 2. The screw removing method according to claim 1, further comprising repeating swinging and forward and backward movements of the tip of the robot arm in the screw pulling direction within a range of resistance force equal to or less than a specified value to pull out the screw to a predetermined position.

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