JP6154689B2 - Automatic screwing machine - Google Patents

Description

  The present invention relates to an automatic screw tightening machine for fastening a screw to a workpiece.

  As shown in Patent Document 1, a conventional automatic screw tightener includes a bit that is rotated by being driven by a rotational drive source, a reciprocating drive unit that can reciprocate the bit in parallel with its axial direction, and the reciprocating drive unit. And a control device that controls the driving of the motor. The reciprocating drive unit is configured to be able to detect a load corresponding to a thrust applied to the bit during the reciprocating drive, and a thrust applied to the bit when a screw is screwed into the workpiece by the control device. There is a feature that is appropriately set according to the material of the workpiece. As a result, the conventional automatic screw tightening machine can set the thrust of the screw to be screwed into the bit, so that it does not hold down the work strongly, and can be controlled so as not to be damaged even if the work is low in strength, for example. .

  Further, the conventional automatic screw tightening machine capable of controlling the thrust of the bit described above often includes a screw guide for sucking a screw before screwing shown in Patent Document 2. In this case, when the screw is screwed in, the work fastening surface and the tip of the screw guide come into contact with each other, and there is a problem that the work fastening surface is easily damaged.

  Therefore, Patent Document 2 discloses a device devised to solve the above-described problem. This conventional automatic screw tightening machine includes a bit that rotates under the drive of a rotational drive source, a cylindrical screw guide that always contains the bit, and an air suction means that can suck air from the tip of the screw guide. And a chuck unit having two claws urged in a normally closing direction, and a reciprocating drive unit capable of reciprocating the bit in the axial direction thereof. In addition, since a compression spring is disposed behind the screw guide so as to include the bit, the screw guide is always urged forward. Accordingly, when an external force is applied to the screw guide, the compression spring is bent, so that the bit protrudes from the screw guide. Further, a locking member is fixed to the outer periphery of the screw guide, and stopper means capable of coming into contact with the locking member is disposed on a moving path of the locking member.

  Next, the operation of the conventional automatic screw tightener will be described. The bit is rotated by driving the rotary drive source, and both the bit and the screw guide are lowered by driving the reciprocating drive unit. At this time, a screw to be screwed into the workpiece is appropriately supplied into the chuck unit and held by the two claws, and the screw supplied by the operation of the air suction means is inserted into the screw guide from its head. Sucked. Further, the screw guide protrudes from the chuck unit by abutting the claws and swinging the two claws.

  After that, the screw guide continues to suck the screw and continues to descend, and the stopper means operates immediately before the tip of the screw guide comes into contact with the surface of the workpiece (hereinafter referred to as a fastening surface). As a result, the stopper means and the locking member come into contact with each other, so that the compression spring bends and the screw guide moves with a slight gap between the tip of the screw guide and the fastening surface. Stop. At this time, since the rotation drive source and the reciprocating unit are continuously driven, the bit moves in a direction protruding from the tip of the screw guide, and the screw is rotated by the rotating bit. Is screwed into the workpiece. Therefore, the conventional automatic screw tightening machine can stop the movement of the screw guide by driving the stopper means and set the tip of the screw guide so that it does not come into contact with the fastening surface. There is a feature that can be screwed without attaching.

JP 2002-254345 JP JP 2000-190142 A

  However, the conventional automatic screw tightening machine cannot flexibly cope with workpieces having different fastening surface heights or different types of workpieces for different types of workpieces. Specifically, in order to cope with many fastening surface heights, it is necessary to arrange a large number of the stopper means in accordance with the number of corresponding fastening surface heights. Therefore, it is necessary to secure a wide space for arranging the stopper means, which causes a problem that the automatic screw tightening machine becomes large. Further, since the stopper means arranged in this way are independent drive sources, there is a problem that the drive control becomes complicated. Further, when the claw closed by the movement of the screw guide is expanded, the compression spring may be bent by this resistance. For this reason, the screw sucked into the screw guide is pushed out by the bit substantially above the fastening surface of the workpiece and protrudes from the tip of the screw guide. As a result, there has been a problem in that the screw is released from being sucked and dropped onto the work and is not screwed into the work.

  The present invention has been created in view of the above problems, and even when fastening screws to a workpiece having a large number of fastening surfaces, the screw guide stop position can be easily adjusted in accordance with the height of each fastening surface. The purpose is to provide an automatic screwing machine that can be changed.

In order to achieve this object, an automatic screw tightening machine according to the present invention rotates by receiving a drive from a rotary drive source and is slidable in the extending direction of the rotary drive source, and a bit connected to the rotary member. A screw tightening tool comprising: a bit reciprocating means that rotatably supports the rotating member and reciprocates the rotating member in a direction in which the bit extends; and a screw that encloses the bit and sucks the screw An automatic screw tightening machine comprising a guide and comprising a screw reciprocating means reciprocally movable in the direction in which the bit extends in the direction in which the bit reciprocates , and the reciprocating means includes a screw guide relative to the bit. The bit reciprocating means is fixed so as to reciprocate integrally with the bit without being moved. Characterized by being configured to be allowed to move relative to the slide guides. The reciprocating means preferably includes an AC servomotor, a ball screw connected to the AC servomotor, and a movable nut that reciprocates by rotation of the ball screw. The bit reciprocating means preferably includes an AC servomotor, a ball screw connected to the AC servomotor, and a movable nut that reciprocates by rotation of the ball screw.

  In the automatic screw tightening machine 1 according to the present invention, the screw guide is moved by driving the reciprocating means and the bit can be moved by driving the bit reciprocating means. The position can be arbitrarily set, and the movement of only the bit can be controlled from the stopped state of the screw guide. That is, since the conventional stopper means is not required, there is an advantage that the automatic screw tightening machine can be configured compactly. In addition, since the automatic screw tightening machine 1 of the present invention only needs to manage the setting of the stop position of the screw guide only for the stop position of the reciprocating means, the advantage is that drive control can be easily performed compared to the drive control of a large number of conventional stopper means. There is also. Furthermore, in the automatic screw tightening machine 1 of the present invention, the screw guide does not move relative to the bit unless the bit reciprocating means is driven. Therefore, the screw guide does not move relative to the bit even when an external force is applied to the screw guide as in the prior art. For this reason, even if the screw guide passes through the chuck unit and receives the urging force (resistance) of the claw, there is an advantage that the screw sucked in the screw guide is pushed out by the bit and does not fall on the workpiece. is there.

It is a partially cutaway sectional view showing an embodiment of an automatic screw tightening machine according to the present invention. FIG. 2 is a partially cutaway cross-sectional view showing a state where a screw tightening operation has progressed from the state of FIG. 1. FIG. 3 is a partially cutaway cross-sectional view showing a state in which a screw tightening operation has progressed from the state of FIG. 2. It is explanatory drawing which shows one Embodiment of the screwing robot carrying the automatic screwing machine which concerns on this invention. It is a partially cutaway sectional view showing another embodiment according to the present invention.

  An embodiment of the automatic screw tightening machine of the present invention will be described below with reference to FIGS. The automatic screw tightening machine 1 of the present invention includes a screw tightening tool 10 provided with a bit 3 that can be engaged with a screw S, a bit reciprocating means 30 that can rotate and reciprocate the bit 3, and the screw. The fastening tool 10 and the bit reciprocating means 30 are provided with a reciprocating means 20 capable of reciprocating.

  The screw tightening tool 10 rotates integrally with an AC servo motor (hereinafter referred to as a bit rotation motor 4) that is an example of a rotation drive source and a drive shaft 4a of the bit rotation motor 4, and slides along the drive shaft 4a. The rotary member 2 is movable, and the bit 3 is connected to the rotary member 2. The bit rotation motor 4 includes an encoder that detects the rotation angle of the drive shaft 4a.

  The drive shaft 4a is formed by connecting a connecting shaft 4b to the tip, and a pin 4c orthogonal to the axis is press-fitted into the connecting shaft 4b.

  The rotating member 2 includes an insertion hole through which the drive shaft 4a and the connection shaft 4b can be inserted, and a groove 2a provided along the direction in which the insertion hole extends is formed in the insertion hole. Since the pin 4c is always in contact with the groove 2a, the rotating member 2 is configured to slide along the drive shaft 4a and rotate integrally with the drive shaft 4a.

  The bit 3 has one end connected to the rotating member 2 and the other end formed to engage with a drive hole (not shown) of the screw S. Therefore, the bit 3 is rotated by driving the bit rotation motor 4.

  The bit reciprocating means 30 includes a motor fixing plate 31 that fixes the bit rotating motor 4, and an AC servo motor that is an example of a rotation driving source that is fixed to the motor fixing plate 31 and arranged side by side with the bit rotating motor 4. (Hereinafter referred to as a first lifting motor 32), a ball screw 33 connected to the first lifting motor 32, and a threaded engagement with the ball screw 33 to reciprocate in accordance with the rotational drive of the first lifting motor 32. The movable nut 34 includes a movable nut 34 and a connecting member 35 that is fixed to the movable nut 34 and reciprocates together with the movable nut 34. The first elevating motor 32 includes an encoder capable of detecting its own rotation angle, and can drive the elevating position of the connecting member 35 to a predetermined position. Further, the motor fixing plate 31 and a lift plate 24 to be described later are connected by a post (not shown).

  The reciprocating means 20 includes an AC servo motor (hereinafter referred to as a second lifting / lowering motor 23) that is an example of a rotational drive source, a ball screw 21 connected to the second lifting / lowering motor 23, and a threaded engagement with the ball screw 21. A movable nut 22 that reciprocates in accordance with the rotational drive of the second elevating motor 23, a shaft 25 that extends parallel to the ball screw 21, and a slide bush that is inserted through the shaft 25 and is slidable along the shaft 25. 26, an elevating plate 24 fixed to the movable nut 22 and the slide bush 26, and a base plate 27 disposed along the extending direction of the shaft 25. The second lifting / lowering motor 23 includes an encoder capable of detecting its own rotation angle, and is driven and controlled based on a signal from the encoder, so that the lifting / lowering plate 24 can be moved to a predetermined height.

  The elevating plate 24 includes a passage hole through which the rotating member 2 can pass while rotatably supporting one end of the ball screw 33. Accordingly, the screw tightening tool 10 and the bit reciprocating means 30 are moved up and down by driving the second lifting motor 23, while the bit 3 is moved up and down together with the rotating member 2 by driving the first lifting motor 32. A screw guide 5 that includes the bit 3 so as to be freely inserted and a joint 6 that is connected to a suction path that is a gap between the screw guide 5 and the bit 3 are disposed at the lower portion of the elevating plate 24. The joint 6 is connected to an air suction means 40 for sucking air. Therefore, when the air suction means 40 is activated, air is sucked from the tip of the screw guide 5.

  Further, a chuck unit 13 capable of temporarily holding the screw S is disposed at the lower end of the reciprocating means 20, and the chuck unit 13 includes a pair of guide grooves that can hold the screw S. The swing claw 11 includes a swing pipe 12 connected to the guide groove of the swing claw 11.

  The swinging claw 11 is normally urged in a closing direction by a spring (not shown), and when the screw guide 5 is lowered, it comes into contact with the tip and outer periphery of the screw guide 5. Expand. Further, the guide groove in the closed state is formed such that the upper portion thereof can pass through the head of the screw S, and the lower portion communicating with the guide groove is gradually narrowed downward, and the shaft portion of the screw S is inserted. Configured to be possible. Therefore, when the swing claw 11 is in the closed state, the screw S can be suspended and held as shown in FIG.

  The rocking pipe 12 is provided with a pipe spring that urges the rocking movement, and is always in communication with the guide groove of the rocking claw 11. When the screw guide 5 is lowered, the tip of the screw guide 5 is moved. Further, since it comes into contact with the outer periphery, it swings against the aforementioned urging.

  The rocking pipe 12 is connected to a screw feeder (not shown) for supplying the screw S, and the screws S are supplied one by one from the screw feeder. Therefore, the screw S supplied from the screw feeder passes through the swing pipe 12 and is supplied to the guide groove of the swing claw 11 and is suspended and held by the swing claw 11.

  Furthermore, the automatic screw tightening machine 1 of the present invention includes a control device (not shown) that can drive and control the bit rotation motor 4, the second lifting / lowering motor 23, and the first lifting / lowering motor 32. This control device is configured to be able to calculate the rotational speed of the bit 3 and the torque applied to the bit 3 from the load current of the bit rotating motor 4. Thereby, the bit 3 can be controlled to rotate based on the preset rotation speed and the calculated torque.

  Since the control device is configured to be able to set the number of rotations to be applied to the ball screws 21 and 33, it can control the speed when the bit 3 and the screw guide 5 are reciprocated. Further, since the control device is configured to be able to calculate the torque applied to the ball screw 33 from the load current of the first lifting / lowering motor 32, it is possible to obtain the thrust during the reciprocating movement of the bit 3. . That is, the control device drives and controls the first elevating motor 32 while checking whether or not the thrust when the bit 3 is lowered exhibits a preset thrust. Thereby, a predetermined thrust is applied when the bit 3 is lowered. The control device is also configured to be able to detect the positions (heights) of the bit 3 and the screw guide 5. This is because, as described above, the detection signals from the respective encoders of the first lifting motor 32 and the second lifting motor 23 and the movable nuts 22 and 34 per one rotation of the ball screws 21 and 33 are advanced. This is because the positions of the movable nuts 22 and 34 are calculated from the distance.

  The automatic screw tightening machine 1 configured as described above is supported by a robot 50 as shown in FIG. The robot 50 includes a slide unit 52 that is disposed above the column 51 and is movable in the front-rear direction, and a turning unit 54 that is fixed to the slide unit 52 and supports an arm 53 so as to be turnable. A connecting plate 55 to which the air suction means 40 is fixed is fixed to the tip of the arm 53, and the base plate is fixed to the connecting plate 55. Thereby, the robot 50 can move the automatic screw tightening machine 1 to a predetermined position above the workpiece.

  Next, the operation of the automatic screw tightening machine 1 of the present invention will be described. The robot 50 operates the slide unit 52 and the turning unit 54 in response to a command from the control device, and moves the automatic screw tightening machine 1 to a predetermined position. As a result, the bit 3 is positioned above the screw P for being placed on the workpiece as shown in FIG.

  When the screw S is supplied from the screw feeder to the chuck unit 13, the control device gives drive commands to the air suction means 40, the bit rotation motor 4 and the second lifting motor 23, respectively. Air is sucked from the tip of the screw guide 5 and the elevating plate 24 is lowered while rotating the bit 3. As a result, the bit 3 is lowered together with the screw guide 5, so that the screw guide 5 is pressed against the swing pipe 12. Since the screw guide 5 that continues to descend reaches the guide groove of the closed swinging claw 11, the screw S held by the swinging claw 11 is sucked into the screw guide 5 and contacts the tip of the bit 3. To do. Further, the screw guide 5 descends and expands the swinging claw 11 that is closed by contacting the guide groove of the swinging claw 11, and the tip of the screw guide 5 reaches a height that does not contact the fastening surface of the workpiece. When descending, the rotation of the second elevating motor 23 stops.

  In the present embodiment, the tip of the screw guide 5 is set to a height that does not contact the fastening surface as described above, and for each workpiece having a step as shown in FIG. Settings are made in advance according to the surface height.

  As described above, when the lowering of the screw guide 5 stops at the position shown in FIG. 2, the control device sends a drive command to the first elevating motor 32, so that the rotating bit 3 is stopped. 5 is lowered to the front end side and securely engaged with the sucked screw S.

  Further, since the bit 3 is lowered, the screw S sucked into the screw guide 5 is pushed out of the screw guide 5 by the bit 3. As a result, the screw S reaches the female screw P, receives the rotation of the bit 3, and is screwed into the female screw P. When the screw S begins to be screwed into the female screw P, the control device sends a signal to the air suction means 40 to stop air suction, and the tightening torque of the screw S reaches a predetermined value. Until then, the bit rotation motor 4 and the first lifting / lowering motor 32 are continuously driven. Therefore, since the bit 3 is lowered and rotated while being applied with the above-described thrust, the screw S can be securely fastened to the workpiece.

  As described above, the automatic screw tightening machine 1 of the present invention reciprocates the screw guide 5 and the bit 3 by driving different driving sources (the second lifting motor 23 and the first lifting motor 32). Since it is a structure to be made, the downward position of the screw guide 5 and the bit 3 can be managed individually. Furthermore, the automatic screw tightening machine 1 according to the present invention can be applied to the screw guide 5 as in the prior art even when the urging force of the swinging claw 11 or the swinging pipe 12 is lowered as described above. Will not be hindered. This is because the screw guide 5 is not provided with a conventional compression spring. Therefore, even if an external force that prevents the screw guide 5 from descending occurs, the screw guide 5 does not move relative to the bit 3, so that the screw S sucked by the screw guide 5 is applied to the bit 3 while the screw guide 5 is descending. There is no problem of being pushed out and falling onto the workpiece.

  In the present embodiment, the thrust when the bit 34 is lowered is controlled. However, the present invention is not limited to this. For example, the torque applied to the ball screw 21 is applied to the second lifting motor 23. May be calculated from the load current and converted as the thrust of the screw guide 5. As a result, even if an abnormal load occurs when the swing pipe 12 swings or the swing claw 11 expands, and the swing of the swing guide 12 is difficult to swing or expand, the thrust of the screw guide 5 is When the set thrust of the set screw guide 5 is exceeded, the driving of the second elevating motor 23 can be stopped at this point. Therefore, it is determined that the thrust of the screw guide 5 that contacts the rocking pipe 12 or the rocking claw 11 is abnormally loaded, and the descent of the screw guide 5 can be interrupted at this time, so that the screw guide 5 or the like is damaged. Can be prevented.

DESCRIPTION OF SYMBOLS 1 Automatic screwing machine 2 Rotating member 2a Groove 3 Bit 4 Bit rotating motor 4a Drive shaft 4b Connecting shaft 4c Pin 5 Screw guide 11 Oscillating claw 13 Chuck unit 20 Reciprocating means 24 Lifting plate 30 Bit reciprocating means 35 Connecting member S Screw P Female thread

Claims (3)

A screw tightening tool comprising: a rotary member that rotates in response to the drive of the rotary drive source and is slidable in a direction in which the rotary drive source extends; and a bit connected to the rotary member;
A bit reciprocating means for rotatably supporting the rotating member and reciprocatingly moving the rotating member in the extending direction of the bit;
In an automatic screw tightening machine comprising a screw guide that encloses the bit and sucks a screw, the screw tightening tool and a reciprocating means that can reciprocate the bit reciprocating means in the extending direction of the bit ,
The reciprocating means is fixed to reciprocate integrally with the bit without moving the screw guide relative to the bit,
2. The automatic screwing machine according to claim 1, wherein the bit reciprocating means is configured to move the bit relative to the screw guide .   2. The automatic screw tightening according to claim 1, wherein the reciprocating means comprises an AC servo motor, a ball screw connected to the AC servo motor, and a movable nut that reciprocates by rotation of the ball screw. Machine.   3. The bit reciprocating means comprises an AC servo motor, a ball screw connected to the AC servo motor, and a movable nut that reciprocates by rotation of the ball screw. Automatic screw tightening machine as described.

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