JP2014124765A - Automatic thread fastening device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic thread fastening device capable of teaching a thread fastening point effectively.SOLUTION: An automatic thread fastening device comprises a driver tool 3 having a bit 34 engaged with a screw, a CCD camera 4 arranged side by side with the driver tool 3, a transfer unit 2 for transferring the driver tool 3 and the CCD camera 4 to a predetermined coordinate, and control means for controlling the drive of the driver tool 3 and the transfer unit 2 and the operation of the CCD camera 4. The CCD camera 4 is configured to determine a deviation coordinate from a deviation between a predetermined coordinate in an imaging area 4S in which one thread fastening point Pa is photographed and a central coordinate of a photographing object. The control means is configured to correct the transfer position of the driver tool 3 based on the deviation coordinate and rotate the bit 34 rotationally. Thus, the position of the bit 34 is surely matched to the position of the thread fastening point Pa every time the thread is fastened.

Description

  According to the present invention, a screw tightening point that is a position to screw a screw can be set in advance in a wide shooting area, and an automatic screw tightening that can determine an actual screw tightening point from an image of the screw tightening point photographed in this shooting area. Relates to the device.

  As shown in Patent Document 1 and FIG. 2, the conventional automatic screw tightening apparatus screws screws (not shown) into screw tightening points Pm1, Pm2, Pa. This screw is tightened with a predetermined tightening torque. This conventional automatic screw tightening apparatus 101 includes a driver tool 3 having a bit 34 engageable with the screw, which can be rotated and raised at a predetermined speed, and a transfer tool for transferring the driver tool 3 in the front-rear and left-right directions. It is comprised from the mounting unit 2, and the control means (not shown) which drives and controls the said driver tool 3 and the said transfer unit 2, respectively.

  The driver tool 3 includes a motor 33 that is an example of a rotational drive source that imparts rotation to the bit 34, and the motor 33 is directly connected to the bit 34. The motor 33 is configured to be movable up and down integrally with the bit 34 by receiving an operation of an air cylinder 32 that can be expanded and contracted by supplying compressed air.

  The transfer unit 2 includes a first transfer means 23 fixed to the driver tool 3 and configured to reciprocate in the X direction of FIG. 2, and a second transfer unit configured to reciprocate in the Y direction of FIG. The first transfer means 23 is loaded on the second transfer means 22. Further, the first transfer means 23 is provided with a movable table 21 that can reciprocate in the X direction, and imaging means for photographing the driver tool 3 and the entire work W are fixed to the movable table 21, respectively. Has been. Accordingly, the driver tool 3 and the CCD camera 140 as an example of the photographing unit can be moved over the workpiece W by the first transfer unit 23 and the second transfer unit 22. Further, the first transfer means 23 and the second transfer means 22 are each provided with a ball screw and an AC servo motor (not shown) inside, and the driver is controlled by driving the AC servo motor. The tool 3 and the CCD camera 140 are transferred to arbitrary coordinates.

  The CCD camera 140 can photograph the entire workpiece W having a plurality of screw tightening points as shown in FIG. 2B, and can recognize the coordinates of the photographed screw tightening points Pm1 and Pm2. . The CCD camera 140 is configured to be able to detect the shooting center coordinates that are the center positions of the screwing points Pm1 and Pm2 that have been shot, and to be able to transmit the detected shooting center coordinates to the control means. Has been.

  When the photographing center coordinates of the screw tightening points Pm1 and Pm2 are input from the CCD camera 140, the control unit performs other operations according to the coordinate information of other screw tightening points set in advance with reference to the photographing center coordinates. Are configured to obtain the coordinates of the screw tightening points Pa. Therefore, the control means recognizes the deviation of the actual position of the workpiece W before the screw tightening, obtains the deviation that is shifted, and this deviation is set at each of the other screw tightening points Pa. It is configured to be able to correct the position by reflecting.

  Further, as can be seen from the above, the control means matches the target coordinates that coincide with the centers of the regular screw tightening points Pm1, Pm2, Pa... Are set in advance. These plural target coordinates are the coordinate information described above. The setting of the target coordinates is generally referred to as teaching. This teaching is performed in advance for each type of work, and if there are a plurality of screw tightening points, the screw tightening points are set. Is performed multiple times.

  Therefore, the conventional automatic screw tightening apparatus 101 recognizes the shift of the positions of all the screw tightening points before the screw tightening, and can collectively correct the position based on the deviation obtained from the shift of the positions. The bit 34 can be transferred so that the center of the bit 34 is located at the center of the screw tightening point which is shifted.

JP2003-225837

  As described above, the conventional automatic screw tightening apparatus 101 photographs the entire work W before the screw tightening by the photographing means, and shifts all screw tightening points arranged on the work W from this one photographing. Correct all at once. Further, since the post-screw tightening is performed sequentially after the collective correction, the workpiece W may be larger than the initial position due to the torque generated at the time of the screw tightening. In other words, the conventional automatic screw tightening apparatus 101 sequentially performs screw tightening without performing correction after performing the above-described collective correction before screw tightening, so it can be determined whether the position is shifted due to screw tightening, It is not possible to calculate whether the position is misaligned. Therefore, if the position of the workpiece W is displaced due to screw tightening, the position of the actual screw tightening point and the bit 34 does not completely coincide with each other after this position misalignment, so that the screw is securely screwed to the screw tightening point. There was a problem that could not be entered. In addition, the conventional automatic screw tightening apparatus 101 has a problem that it takes time to teach because the target coordinates of each screw tightening point must be accurately taught. The reason is that if the taught target coordinates are set incorrectly, the corrected position of the bit 34 is corrected based on the incorrectly taught target coordinates, and the actual screw tightening is performed. It is clear from the fact that the points do not match. Further, the conventional automatic screw tightening apparatus 101 cannot adjust the height from the surface of the workpiece W to the CCD camera 4 because the CCD camera 4 is fixed to the transfer unit 2. Therefore, for example, if the work has a step (not shown) in which a number of screw tightening points having different heights are arranged, the screw tightening point of one height is not focused on the captured image. The conventional screw tightening apparatus 101 has a problem that it can deal only with a work at a screw tightening point having the same height.

  The present invention has been made in view of the above problems, and an object thereof is to provide an automatic screw tightening device that can efficiently teach a screw tightening point. In order to achieve this object, a screwdriver tool that is fitted with a screw and has a rotatable bit and can be screwed into a screw fastening point provided on a work, and a driver tool that is arranged in line with the screwdriver tool and that Imaging means capable of imaging the screw tightening point, transfer unit for transferring the imaging means and the driver tool to desired positions, and control means capable of controlling the transfer unit, the driver tool, and the imaging means, respectively. In the automatic screw tightening apparatus that corrects the transfer position of the driver tool from the photographed screw tightening point image and tightens the screw, the photographing means has a predetermined photographing area including one screw tightening point. In addition to shooting, the center of the screw tightening point shot in this shooting area and the shooting preset in the shooting area. While the configuration is such that the deviation coordinates are obtained from the deviation from the reference coordinates, the control means moves the driver tool based on the preset offset coordinates and the deviation coordinates that do not always change between the bit and the photographing means. The bit is configured to be rotationally driven and controlled. The photographing means is loaded on a reciprocating means that can reciprocate in a direction approaching or separating from the screw tightening point, the reciprocating means is fixed to the transfer unit, and the reciprocating means is controlled by the control means. The drive control may be performed to adjust the distance from the surface of the screw tightening point to the photographing means. Furthermore, the control unit may be configured to drive and control the transfer unit so as to photograph the periphery of the photographing area when the screwing point cannot be recognized by the photographing unit.

  The automatic screw tightening device 1 of the present invention images the screw tightening point Pa where the screw tightening is performed before screw tightening, and recognizes the situation such as the position and shape of the photographed screw tightening point Pa. For this reason, for example, it is possible to detect deformation of the screw tightening point Pa, clogging of foreign matter, and the like, and even if the workpiece W is displaced from the normal position by screw tightening, the position of the driver tool 3 is tightened each time. There is an advantage that can be corrected before. Further, the automatic screw tightening device 1 of the present invention photographs one screw tightening point Pa in the photographing area 4S, and based on the information of the image photographed in the photographing area 4S, the driver tool 3 is actually screwed point. The position is corrected so as to meet Pa. As a result, the teaching of the screw tightening point Pa in the present invention may be performed over a wide range so that the regular screw tightening point can be accommodated in the photographing area 4S. It is not necessary to set the target coordinates that coincide with. Therefore, since the automatic screw tightening apparatus 1 of the present invention can perform rough teaching using the CCD camera 4, there is an advantage that the teaching time for one workpiece W can be greatly shortened as compared with the prior art. Furthermore, since the automatic screw tightening device 1 of the present invention can transfer the photographing means in a direction approaching or moving away from the screw tightening point Pa, for example, even at screw tightening points having different heights such as steps, The image of the screw tightening point can be reliably focused. Therefore, there is also an advantage that the screw tightening point in the photographing area 4S can be reliably detected even if the screw tightening point has a different height. Furthermore, the automatic screw tightening device 1 of the present invention can sequentially photograph the periphery of the photographing area 4S once photographed when the screw tightening point is out of the photographing area 4S and cannot be recognized, such as when the work W is deviated from the normal position. Therefore, the automatic screw tightening device 1 of the present invention moves the photographing means so as to find the screw tightening point Pa that has been shifted a predetermined number of times even when the work W has shifted more than the normal position. There is also an advantage that can be.

It is a schematic explanatory drawing which shows one Example of the automatic screw fastening apparatus which concerns on this invention. Further, (a) is a perspective view, and (b) is an explanatory diagram of an image photographed by photographing means. It is a schematic explanatory drawing which shows one conventional example. Further, (a) is a perspective view, and (b) is an explanatory diagram of an image photographed by photographing means.

  As shown in Patent Document 1 and FIG. 1, the automatic screw tightening device of the present invention screws a screw (not shown) into a plurality of screw tightening points Pa... It is tightened with a predetermined tightening torque. The automatic screw tightening device 1 includes a driver tool 3 provided with a bit 34 engageable with the screw so that the bit 34 can be rotated and moved up and down at a predetermined speed, and a transfer unit that transfers the driver tool 3 in the front, rear, left, and right directions 2 and control means (not shown) for driving and controlling the driver tool 3 and the transfer unit 2 respectively.

  The driver tool 3 includes a motor 33 that is an example of a rotational drive source that imparts rotation to the bit 34, and the motor 33 is directly connected to the bit 34. The motor 33 is configured to be movable up and down integrally with the bit 34 by receiving an operation of an air cylinder 32 that can be expanded and contracted by supplying compressed air. Instead of the air cylinder 32, a ball screw (not shown) may be arranged in parallel to the extending direction of the bit 34, and this ball screw may be replaced with an elevating means configured to be directly connected to an AC servo motor (not shown). . Since the configuration of the driver tool including the ball screw and the AC servo motor has already been disclosed in Japanese Patent No. 3797598, the detailed description thereof is omitted here.

  The transfer unit 2 is capable of reciprocating in the Y direction in FIG. 1A and the first transfer means 23 fixed to the driver tool 3 and configured to reciprocate in the X direction in FIG. The first transfer means 23 is stacked on the second transfer means 22. The first transfer means 23 is provided with a movable table 21 that can reciprocate in the X direction. On the movable table 21, photographing means capable of photographing the driver tool 3 and the screw tightening point are respectively provided. It is fixed. Accordingly, the driver tool 3 and the CCD camera 4 as an example of the photographing unit can be moved over the work W by the first transfer unit 23 and the second transfer unit 22. Further, the first transfer means 23 and the second transfer means 22 are each provided with a ball screw and an AC servo motor (not shown) inside, and the driver is controlled by driving the AC servo motor. The tool 3 and the CCD camera 4 are transferred to arbitrary coordinates. Further, a third transfer means 24 is interposed between the movable table 21 and the CCD camera 4, and the third transfer means 24 can reciprocate in the Z direction of FIG. It is configured. Therefore, the CCD camera 4 is movable in the Z direction approaching or leaving the screw tightening point Pa. The third transfer means 24 may not be arranged by constituting the driver tool in which the air cylinder 32 is replaced with an AC servo motor and a ball screw as described above. In this case, the CCD camera 4 is directly fixed to a member (not shown) attached to the motor 33 and can be moved up and down together with the bit 34.

  The CCD camera 4 can photograph a predetermined area (hereinafter referred to as a photographing area 4S) including one of the screw tightening points from above the work W. The photographing area 4S is shown in FIG. Thus, in the present embodiment, the range is set to 5 mm × 5 mm. Further, the CCD camera 4 sets the photographing center coordinates that are the center of the screwing point Pa photographed in the photographing area 4S and the photographing reference coordinates that are the intersections of the two two-dot chain lines shown in FIG. It is configured to be able to recognize, and is configured to be able to calculate the deviation (that is, the amount of deviation) between the shooting center coordinates and the shooting reference coordinates. Further, the CCD camera 4 is configured such that a deviation coordinate is obtained from the calculated deviation, and the deviation coordinate can be transmitted to a control means described later. The deviation coordinates are X = + 1 mm and Y = + 1 mm in FIG. 1B in the present embodiment. The photographing area 4S can be set to a wide range or a narrow range by changing the lens attached to the tip of the CCD camera 4, and this selection is expected to be the diameter of the screw fastening point Pa to be photographed or expected. Needless to say, it is set in advance in consideration of the displacement of the workpiece position. Further, in this embodiment, the range of the photographing area 4s is 5 mm × 5 mm, but is not limited to this size, and may be changed each time by changing the lens as described above.

  In the control means, an offset amount which is a positional relationship between the bit 34 and the CCD camera 4 is set in advance, and the offset amount is deviated from the photographing reference coordinate with respect to the bit center coordinate of the bit 34. The offset coordinates indicate whether or not The offset coordinates in the present embodiment are X = -15 mm and Y = 0 mm. When the deviation coordinates (X = + 1 mm, Y = + 1 mm) sent from the CCD camera 4 are input to the control means, the transfer coordinates of the driver tool 3 are based on the deviation coordinates and the offset coordinates. Can be calculated. That is, the calculated transfer coordinates described above are X = -14 mm and Y = + 1 mm, and this information is set inside the control means. As a result, the control means controls the drive of the first transfer means 23 and the second transfer means 22 based on the transfer coordinates, so that the driver tool 3 is screwed at the center of the bit 34. Transferred so as to coincide with the center of the fastening point Pa.

  Next, the operation of the automatic screw tightening device 1 of the present invention will be described below. In the automatic screw tightening apparatus 1, the first transfer means 23 and the second transfer means 22 that have received a command from the control means move. As a result, the CCD camera 4 is transferred over the preset workpiece W, and a desired screwing point Pa is photographed at this position. At this time, as shown in FIG. 1B and as described above, if the deviation coordinates are X = + 1 mm and Y = + 1 mm, the deviation coordinates (+1 mm, Y = + 1 mm) and the offset coordinates (X = −15 mm, Y = 0 mm), the control means calculates and stores the transfer coordinates (−14 mm, Y = + 1 mm) of the driver tool 3. Thereafter, the control means drives and controls the first transfer means 23 and the second transfer means 22 based on the transfer coordinates, so that the driver tool 3 is transferred above the screw tightening point Pa. As a result, the center of the photographed screw fastening point Pa coincides with the center of the bit 34. Thereafter, the control means drives and controls the air cylinder 32 and the motor 33, respectively, so that the bit 34 rotates while descending. As a result, the screw engages with the tip of the bit 34 and is screwed into the screw fastening point Pa. When the screw reaches a predetermined tightening torque, the control means instructs the motor 33 to stop rotating and gives a return command to the air cylinder 32. As a result, the bit 34 rises to complete one point of screw tightening. In addition, in the screw tightening after the second point, the same processing as described above is repeated, and it corresponds to screw tightening to a large number of screw tightening points.

  Therefore, the automatic screw tightening apparatus 1 of the present invention performs a control to always photograph the target screw tightening point Pa before the screw tightening by the CCD camera 4 and transfer the driver tool 3 every time considering the deviation. Therefore, there is an advantage that the bit 34 can be reliably transferred to the center of the screw tightening point Pa where the image is taken. Further, since the screw tightening point Pa is enlarged and photographed as compared with the conventional case, there is an advantage that the state of the screw tightening point Pa can be grasped with higher accuracy. As a result, the teaching of the screw tightening point Pa in the present invention may be performed over a wide range so that the regular screw tightening point can be accommodated in the photographing area 4S. It is not necessary to set the target coordinates that coincide with. Therefore, since the automatic screw tightening apparatus 1 of the present invention can perform rough teaching using the CCD camera 4, there is an advantage that the teaching time for one workpiece W can be greatly shortened as compared with the prior art.

  Further, since the CCD camera 4 is mounted on the third transfer means 24, for example, even when the workpiece has a step and the screw tightening points have different heights, the screw tightening to be photographed is performed. The height of the surface of the point and the CCD camera 4 can be adjusted. Thereby, the automatic screw tightening device 1 of the present invention can optimally adjust the focus of an image to be photographed, and thus has an advantage that it can cope with screw tightening points having different heights.

  Further, if the screw tightening point Pa that is the subject of photographing does not fit in the photographing area 4S of the CCD camera 4, the control means cannot accurately recognize the screw tightening point Pa and can calculate the transfer coordinates. It is possible that it will disappear and fall into an error state. However, if the screw tightening point Pa cannot be recognized in the first shooting, the automatic screw tightening device 1 of the present invention transfers the CCD camera 4 to the coordinates where the periphery of the shot shooting area 4S can be shot. Will be retried. As a result, even when the workpiece is greatly displaced due to the screw tightening, the screw tightening point that could not be photographed by the first photographing is repeatedly photographed a predetermined number of times, so that the screw tightening work can be performed efficiently. There is also.

DESCRIPTION OF SYMBOLS 1 Automatic screw fastening apparatus 2 Transfer unit 3 Driver tool 4 CCD camera 21 Movable table 22 2nd transfer means 23 1st transfer means 24 3rd transfer means 34 Bit Pa Screw fastening point W Workpiece

As described above, the conventional automatic screw tightening apparatus 101 photographs the entire work W before the screw tightening by the photographing means, and shifts all screw tightening points arranged on the work W from this one photographing. Correct all at once. Further, since the post-screw tightening is performed sequentially after the collective correction, the workpiece W may be larger than the initial position due to the torque generated at the time of the screw tightening. In other words, the conventional automatic screw tightening apparatus 101 sequentially performs screw tightening without performing correction after performing the above-described collective correction before screw tightening, so it can be determined whether the position is shifted due to screw tightening, It is not possible to calculate whether the position is misaligned. Therefore, if the position of the workpiece W is displaced due to screw tightening, the position of the actual screw tightening point and the bit 34 does not completely coincide with each other after this position misalignment, so that the screw is securely screwed to the screw tightening point. There was a problem that could not be entered. In addition, the conventional automatic screw tightening apparatus 101 has a problem that it takes time to teach because the target coordinates of each screw tightening point must be accurately taught. The reason is that if the taught target coordinates are set incorrectly, the corrected position of the bit 34 is corrected based on the incorrectly taught target coordinates, and the actual screw tightening is performed. It is clear from the fact that the points do not match. Further, the conventional automatic screw tightening apparatus 101 cannot adjust the height from the surface of the workpiece W to the CCD camera 4 because the CCD camera 4 is fixed to the transfer unit 2. Therefore, for example, if the work has a step (not shown) in which a number of screw tightening points having different heights are arranged, the screw tightening point of one height is not focused on the captured image. The conventional automatic screw tightening apparatus 101 has a problem that it can cope only with a work at a screw tightening point having the same height.

Claims (3)

A screwdriver tool that is fitted with a screw and has a rotatable bit and can be screwed into the screw tightening point arranged on the workpiece, and the screw tightening point arranged in line with the driver tool can be photographed. The image capturing means, a transfer unit that transfers the image capturing means and the driver tool to a desired position, and a control means that can control the transfer unit, the driver tool, and the image capturing means, respectively. In the automatic screw tightening device that corrects the transfer position of the driver tool from the image of the screw tightening point and tightens the screw,
The photographing unit photographs a predetermined photographing area including one screw tightening point, the center of the screw tightening point photographed in the photographing area, and photographing reference coordinates preset in the photographing area. And is configured to obtain the deviation coordinates from the deviation of
The control means is configured to transfer the driver tool on the basis of preset offset coordinates and deviation coordinates that do not always change between the bit and the photographing means, and to control the rotational drive of the bit. Screw tightening device.   The photographing means is loaded on a reciprocating means capable of reciprocating in a direction approaching or separating from the screw fastening point, the reciprocating means is fixed to the transfer unit, and the reciprocating means is driven by the control means. The screw tightening device according to claim 1, wherein the screw tightening device is configured to control and adjust the distance from the surface of the screw tightening point to the photographing means.   The said control means is a structure which drives and controls the said transfer unit so that the circumference | surroundings of the said imaging area may be image | photographed, when the said screwing point cannot be recognized by the said imaging | photography means. The screw tightening apparatus as described in.

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