JP2018094655A - Multiple spindle screw fastening device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-axis screw tightening device capable of individually controlling a chuck base and a screw tightening tool base. SOLUTION: A screw tightening tool 10 having a bit B, a screw tightening tool base 20 having a plurality of screw tightening tools 10 mounted and reciprocally movable, and a screw tightening tool base 20 which can be reciprocated and inserted in parallel with the screw tightening tool base 20 It is composed of a chuck base 30 provided with a chuck 40. The screw tightening tool base 20 rotatably supports the first screw nut 22 screwed to the first ball screw shaft 21 extending in the moving direction thereof, and the first servo connected to the first ball screw shaft 21. A motor 23 is provided. Further, the chuck base 30 rotatably supports the second screw nut 32 screwed into the second ball screw shaft 31 extending along the reciprocating movement direction thereof, and is connected to the second ball screw shaft 31. A servomotor 33 is provided. Therefore, since the drive control of the screw tightening tool base 20 and the chuck base 30 can be performed individually, it is possible to handle work Ws having different tightening heights h. [Selection diagram] Fig. 1

Description

  The present invention relates to a multi-axis screw fastening device that lifts and lowers a plurality of bits and a chuck to fasten a screw to a workpiece.

  As shown in Patent Document 1 and Patent Document 2, a conventional multi-axis screw tightening device includes a screw tightening tool including a bit that can be rotated by being fitted to a screw to be fastened to a workpiece, and a plurality of the screw tightening tools. It is comprised from the raising / lowering unit which makes it raise / lower freely.

  The screw tightening tool disclosed in Patent Document 1 is provided with one bit rotating motor for each bit, and the bits are respectively inserted and arranged in chucks that hold a screw temporarily. Yes.

  On the other hand, the screw tightening tool disclosed in Patent Document 2 includes a bit rotation motor that imparts rotation to each of a plurality of bits, and a coil spring that is disposed at the tip of the bit. A taper hole that contacts the screw is formed.

  In addition, an elevating unit disclosed in Patent Document 1 includes an elevating cylinder that can be moved up and down in a bit extending direction, a screw tightening tool base that moves up and down in response to the operation of the elevating cylinder, and a chuck base to which the chuck is attached. And a stopper that is brought into contact with the lower surface of the chuck base and stops only the chuck base from descending and does not prevent the screw tightening tool base from descending. Thus, after the screw tightening tool base and the chuck base are integrally lowered toward the workpiece, if the tip of the chuck is lowered to a height located on the surface of the workpiece, the lowering of the chuck base is stopped by the stopper. Only the screw tightening tool base continues to descend. Therefore, the bit opens the tip of the chuck and screws the screw held in the chuck into the workpiece.

  On the other hand, the elevating unit disclosed in Patent Document 2 imparts rotation to the ball screw shaft disposed along the extending direction of the bit, a screw nut that is screwed to the ball screw shaft, and the ball screw shaft. It consists of a lifting motor. In addition, the screw nut is rotatably arranged on a fixed plate through which the bit is slidably inserted, so that the ball screw shaft and the bit are moved up and down simultaneously by forward and reverse rotation of the lift motor. be able to.

  The conventional multi-axis screw tightening device configured as described above has a coil spring disposed at the tip of the bit and a tapered hole in the fitting portion, so that the screw temporarily tightened on the workpiece is slightly positioned. Even if they are misaligned, there is a feature that the tip end portion of the bit changes its position along the axis of the screw by the deformation of the coil spring and self-alignment is performed.

JP 59-134628 Japanese Utility Model Publication No. 02-039835

  However, since the conventional multi-axis screw fastening device has the coil spring disposed at the tip of the bit, there is a problem that it is not only eccentric about the axis but also bent in the up-and-down direction. As a result, even if the lifting motor is replaced with an AC servo motor capable of position control, the exact bit height cannot be detected. Therefore, the conventional multi-axis screw tightening device cannot determine the exact height position of the bit at the time of tightening the screw with a predetermined torque from the command value of the AC servo motor, etc. could not. Further, even if the above-described lifting cylinder of Patent Document 1 described above is replaced with an AC servo motor and further changed to a lifting unit having a ball screw shaft and a screw nut, the position of the stopper cannot be changed immediately. The stop position of the chuck base cannot be easily changed. That is, the conventional multi-axis screw fastening device has a problem that it cannot cope with workpieces having different fastening heights.

  The multi-axis screw tightening device of the present invention has been created in view of the above problems, and is equipped with a bit that can be engaged with a screw that is screwed into a workpiece and a bit rotation motor that provides rotation to the bit. A tool, a screw tightening tool base on which a plurality of the screw tightening tools are mounted and reciprocally mounted in the extending direction of the bit, and a chuck capable of reciprocating in parallel with the screw tightening tool base and allowing the bit to be inserted. In the multi-axis screw tightening device including the chuck base, the screw tightening tool base rotatably supports a first screw nut that is screwed to a first ball screw shaft extending along the reciprocating direction. And a first servo motor connected to the first ball screw shaft, wherein the chuck base is screwed into a second ball screw shaft extending along a moving direction thereof. And a second servo motor connected to the second ball screw shaft, wherein the first servo motor and the second servo motor have a drive command value consisting of the respective rotation speed and rotation angle. It is characterized in that it is connected to a control means comprising a storage unit that stores in advance and a control unit that controls each rotational drive based on the drive command value of the storage unit.

  The multi-axis screw tightening device according to the present invention includes a storage unit that stores the drive command values of the first servo motor and the second servo motor, respectively, and the first servo motor and the second servo motor based on the drive command values. Since the control means is provided with a control section that controls the driving of the screw tightening tool, the moving distance of the screw tightening tool base and the chuck base can be individually set. Therefore, even when the lowering chuck stop position has to be changed in the vertical direction, such as when the workpiece type is changed, the screw tightening operation according to the workpiece type can be performed by changing the drive command value. There is an advantage that can be easily performed. Also, by setting the drive command value to be set in the storage unit in advance according to the type of workpiece, many types of workpieces to be produced frequently change the type of workpiece, so-called high-mix low-volume production screw tightening work. There is also an advantage that it can be done efficiently.

It is a schematic explanatory drawing showing one embodiment concerning the present invention. FIG. 2 is a partially cutaway cross-sectional explanatory view showing a main part viewed from the right side of FIG. 1.

  A multi-axis screw fastening device 1 according to the present invention will be described with reference to FIGS. 1 and 2. The multi-axis screw tightening device 1 of the present invention includes a plurality of screw tightening tools 10 configured to freely rotate a bit B engageable with a screw (not shown), and these screw tightening tools 10 and 10 are simultaneously moved toward a workpiece W. A screw tightening tool base 20 that can be moved up and down, a chuck base 30 that is attached with chucks 40 and 40 for inserting the bit B and temporarily holding the screw supplied from the outside, the screw tightening tool base 20 and the chuck It is comprised from the control means 50 which can control the position of the stand 30 separately.

  The screw tightening tool 10 includes a bit rotation motor BM disposed on the screw tightening tool base 20 and a bit B that rotates by receiving the rotational drive of the bit rotation motor BM. The bit B has an engaging portion at the tip thereof, and the engaging portion is formed to engage with an engaging hole formed in the head portion of the screw. The bit rotation motors BM and BM are connected to a controller (not shown), respectively, and are configured such that the rotation of the bits B and B can be individually controlled until a tightening set torque preset in the controller is reached. .

  The screw tightening tool base 20 and the chuck base 30 are individually slidably disposed on a frame F standing from a base surface. The frame F includes a bottom plate 61 fixed to the base surface, side plates 62 and 63 which are welded to the upper surface of the bottom plate 61 and extend upward with a predetermined interval therebetween, and the side plates 62 and 63, respectively. A welded base plate 64, rails R, R fixed to the base plate 64 and arranged in parallel at a predetermined interval, and sliding along a direction in which the rail R extends by engaging with the rails R, R. It is composed of a movable sliding block M.

  Four sliding blocks M are arranged for one rail R, and eight sliding blocks M are arranged in the present embodiment. In addition, as shown in FIG. 2, these sliding blocks M can be divided into four pieces located in the upper part and four pieces located in the lower part. 20 is attached, and the chuck base 30 is attached to the lower four sliding blocks M. As a result, the screw tightening tool base 20 and the chuck base 30 can be individually slid in the direction approaching or separating from the workpiece W.

  Further, as shown in FIG. 2, the frame F is provided with the rails R, R at both ends of the base plate 64, and is arranged so as to be sandwiched between the two rails R, R and fixed to the upper portion of the frame F. The upper block 65 and the lower block 66 fixed to the lower part of the frame F are provided. The upper block 65 and the lower block 66 are configured to rotatably support a first ball screw shaft 21 and a second ball screw shaft 31 that are two ball screw shafts.

  Each of the first ball screw shaft 21 and the second ball screw shaft 31 is configured to be individually rotatable, and a first servo motor that applies rotation to the first ball screw shaft 21; The two-ball screw shaft 31 is connected to a second servo motor 33 that imparts rotation. The rotation transmission of the first ball screw shaft 21 and the second ball screw shaft 31 is fixed to the drive pulley and the second ball screw shaft 31 in which the timing belt T is fixed to the second servomotor 33 as shown in FIG. It can be wound around a driven pulley. The rotation transmission configuration of the first ball screw shaft 21 (not shown) is the same as described above.

  The first servo motor and the second servo motor 33 are both AC servo motors, each having an encoder capable of detecting its own rotation angle, and transmitting each of these rotation angles to the control means 50. Become.

  The control means 50 includes a control unit 52 that transmits a drive command to the first servo motor and the second servo motor 33, and a storage unit 51 that can store a plurality of drive command values including specific numerical values of the drive command. The moving speed and moving distance of the screw tightening tool base 20 and the chuck base 30 can be calculated based on the rotation angle emitted from the encoder, the lead angles of the first and second ball screw shafts, and the time of the built-in timer. The calculation part 53 is provided.

  The control unit 52 uses the drive command value stored in advance in the storage unit 51, the moving speed calculated by the calculating unit 53 (hereinafter referred to as a calculated moving speed), and the calculated moving distance (hereinafter referred to as a calculated moving distance). In addition, the first servo motor and the second servo motor 33 are configured to be drive-controlled so that the calculated moving speed and the calculated moving distance match if they do not match the drive command value.

  The storage unit 51 is configured to be able to store the lead angle of the first ball screw shaft 21 and the second ball screw shaft 31, the stop height of the chuck base 30, and the target moving height of the screw tightening tool base 20. Has been. The drive command value includes the target moving height of the screw tightening tool base 20 in addition to the stop height of the chuck base 30 described above.

  The calculation unit 53 is configured to be able to calculate a numerical value, reads the lead angle of each ball screw shaft (21, 31) stored in the storage unit 51, and uses this as a pulse signal emitted from the encoder. Based on this, the moving distances of the screw tightening tool base 20 and the chuck base 30 can be calculated. Similarly, the calculation unit 53 derives the calculated moving speed from the pulse signal, the transmission time, and the lead angle, and transmits this to the control unit 52 each time.

  The chuck 40 is attached to the chuck base 30, and is configured to be able to rotate and insert the bit B, and normally includes the bit B therein. The chuck 40 is configured not only to contain the bit B, but also to be able to temporarily hold a screw supplied from the outside at the tip. A pair of chuck claws urged in a closing direction by a spring (not shown) is arranged at the tip of the chuck 40, and the screw is held by the closed chuck claws. The bit B contained in the chuck 40 is located above the screw held by the chuck claw, and the bit B moves relative to the chuck 40 downward so that the bit B holds the screw. The screw and the bit B can be protruded from the chuck 40 by pushing downward and swinging in the direction in which the chuck claw opens on the head of the screw.

  Next, the operation of the multi-axis screw fastening device 1 according to the present invention will be described. An operator (not shown) sets the workpiece W on the base surface as shown in FIG. As a result, a predetermined distance is created between the upper surface of the workpiece W and the tip of the chuck 40, and this distance becomes the tightening height h. In addition, a plurality of screws are arranged on the workpiece W so as to extend downward from the upper surface thereof, and the female screws are formed so as to be screwable with the screws.

  The multi-axis screw tightening device 1 receives a screw tightening start signal from a device such as a start switch (not shown) attached to the control means 50 by the control unit 52. Thereby, the control unit 52 reads the stop position of the chuck base 30 and the target moving height of the screw tightening tool base 20 and the moving speeds of the chuck base 30 and the screw tightening tool base 20 from the storage unit 51, and the first servo The motor and the second servomotor 33 are rotationally driven and controlled.

  The first servo motor and the second servo motor 33 start rotating at a rotational speed corresponding to the moving speed, rotate the first ball screw shaft 21 and the second ball screw shaft 31, respectively, and from the encoder Transmitting pulse signals to the control unit 52 as needed.

  The first screwing nut 22 and the second screwing nut 32 are moved down along the first ball screw shaft 21 and the second ball screw shaft 31 in a direction approaching the workpiece W. Therefore, the screw tightening tool base 20 and the chuck base 30 are lowered simultaneously while maintaining the same speed.

  Further, the control unit 52 that has received the screw tightening start signal drives and controls the controller to rotate the bit rotation motor BM of the screw tightening tool 10 corresponding thereto in order to send a tool operation command to the controller.

  As a result, the bits B and B are rotated, and the screw tightening tool base 20 and the chuck base 30 are simultaneously lowered, so that the tightening height h shown in FIG. 1 is gradually reduced.

  The control unit 52 constantly monitors the pulse signal generated from the second servo motor 33, calculates the travel distance from the start of lowering of the chuck base 30 to the time point, and the stop height set in the storage unit 53 in advance. And the second servo motor 33 is stopped when the calculated movement distance matches the stop height.

  The stop height is a height at which the tip of the chuck 40 is located several millimeters above the surface of the workpiece W and does not come into contact with the workpiece W when the chuck pawl swings in the opening direction. Corresponding numerical values are preset in the storage unit 53.

  Therefore, when the chuck base 30 reaches the stop height, the lowering operation is stopped, and the screw tightening tool base 20 that continues to descend starts to move relative to the chuck base 30. Therefore, the bits B and B are rotated while pushing the chuck claws from the inside of the chucks 40 and 40 and screwing the screws temporarily held in the chucks 40 and 40 into the workpiece W.

  The bit rotation motor BM gradually increases the load in the rotational direction by the screw seating on the workpiece W, and sends this rotational torque to the controller as needed. Thus, the controller compares this actual actual torque with a preset tightening set torque, and stops the bit rotation motor BM when the actual torque reaches the tightening set torque.

  The control unit 52 stops the rotation of the first servo motor when receiving a stop signal of the bit rotation motor BM issued from the controller and confirming that all the bits have reached a predetermined tightening set torque. As a result, the multi-axis screw tightening device 1 completes the screw tightening work on the workpiece, and rotates the first servo motor and the second servo motor 33 in the opposite direction. As a result, the screw tightening tool base 20 and the chuck base 30 rise all at once and return to their original height positions.

  Further, even if the type of the workpiece W is changed and the tightening height h is different from the previous one, a plurality of the stop height and the target height set in advance in the storage unit are set in accordance with the type of the workpiece W. Thus, the stop height of the chuck base 30 can be set so that the tip end portion of the chuck 40 described above does not come into contact with the workpiece W and the chuck pawl is at a height position where the chuck pawl is opened. Therefore, even if the workpieces W have different tightening heights h, the screw tightening operation can be performed flexibly.

DESCRIPTION OF SYMBOLS 1 Multi-axis screw fastening apparatus 10 Screw tightening tool 20 Screw tightening tool base 21 1st ball screw shaft 22 1st screwing nut 23 1st servomotor 30 Chuck stand 31 2nd ball screw shaft 32 2nd screwing nut 40 Chuck 50 Control means B bit BM bit rotary motor W Workpiece

Claims (1)

A screw tightening tool having a bit engageable with a screw to be screwed into a workpiece and a bit rotating motor for imparting rotation to the bit, and a plurality of the screw tightening tools are mounted and reciprocally movable in the extending direction of the bit In a multi-axis screw tightening device comprising: a mounted screw tightening tool base; and a chuck base including a chuck that can reciprocate in parallel with the screw tightening tool base and pass the bit.
The screw tightening tool base rotatably supports a first screwing nut screwed to a first ball screw shaft extending along the reciprocating direction, and a first servo coupled to the first ball screw shaft. Equipped with a motor,
The chuck base includes a second servo motor that rotatably supports a second threaded nut that is threadedly engaged with a second ball screw shaft that extends in the moving direction, and that is coupled to the second ball screw shaft. ,
The first servo motor and the second servo motor each store a drive command value including a rotation speed and a rotation angle in advance, and control for controlling each rotation drive based on the drive command value of the storage unit. And a multi-axis screw fastening device connected to a control means having a section.

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