JP4359774B2 - Screw tightening device and screw tightening method - Google Patents

Description

  The present invention relates to a screw fastening device and a screw fastening method when fastening a male screw and a female screw.

As a conventional example of a screw fastening device and a screw fastening method for fastening a male screw and a female screw, Patent Literature 1 discloses a fastening method and device for screw parts.
The screw component fastening device disclosed in Patent Document 1 includes a pressing unit that presses screw components together, a reverse driving unit that reversely drives one of the screw components in a pressed state, and screwing of each screw component in a reverse driving state. A screwing position detecting means for detecting the position; and a forward rotation driving means for driving the screw component to rotate forward by detecting the screwing position by the screwing position detecting means. Each screw component is composed of sensors, and in the state where the screw components are pressed against each other and one screw component is driven in reverse, the displacement change rate of one screw component relative to the other screw component is detected by the light emitting / receiving sensor. When screwing is started, that is, when the displacement change rate reaches the maximum, the reverse rotation driving of one screw component is stopped and the normal rotation driving is performed, so that each screw component is screwed.
JP-A-2-224934

As described above, in the invention of Patent Document 1, when the screw parts are pressed against each other and one screw part is driven in reverse, the displacement change rate of one screw part with respect to the other screw part is maximized. Paying attention to the screwing start position of each screw part, a light projecting / receiving sensor is employed as the screwing position detecting means to detect the displacement change rate, and this displacement change rate is equal to one pitch of the screw part. It is extremely small as follows, and it is impossible to accurately measure the displacement change rate due to deflection or backlash of parts constituting the apparatus.
Moreover, the invention of Patent Document 1 is effective when the pitch of the threaded portion is relatively large and the screw tightening operation is repeated at a predetermined location. When performing screw tightening work in a location, the displacement change rate becomes extremely small, and furthermore, since the installation conditions of the device are changed each time, it becomes difficult to accurately measure the displacement change rate. Poor versatility.

  The present invention has been made in view of the above points, and by detecting the screwing start position of the male screw and the female screw with high accuracy, the screwing start of the male screw and the female screw is made smooth, and the both are engaged. An object of the present invention is to provide a screw tightening device and a screw tightening method capable of preventing the above.

According to the present invention, as a means for solving the above-mentioned problems, the invention of the screw tightening device according to claim 1 is a screw tightening device for tightening the male screw and the female screw, and pressing means for pressing the male screw and the female screw. If, when one causes driven forward in the direction of tightening of the male thread or the female screw, driving means for also reverse driven in the direction of loosening, said and said external thread internal thread has reached the engaged position, the external thread and a vibration sensor for detecting vibration when the thread of the female screw has collided, the external thread or in the state of being driven in reverse by the driving means either of the female screw, by the vibration sensor of said external thread and said internal thread when the vibration due to collision of each thread is detected, it is normally driven by said driving means either the male thread or the female screw It is characterized in that it comprises a control means.
According to a second aspect of the present invention, there is provided the screw tightening device according to the first aspect of the present invention, wherein, in the control unit, the control means is configured to determine the male screw and the male screw based on a vibration maximum value detected for each rotation of the male screw. The screwing position with the female screw is determined .

Furthermore, in order to solve the above-described problem, the invention of the screw tightening method according to claim 3 is the screw tightening method for tightening the male screw and the female screw, while pressing the male screw and the female screw while pressing the male screw or the female screw. When the male screw and the female screw reach the screwing position in a state in which one of the female screws is driven in the direction of loosening, and vibrations are detected when the male screw and the female screw collide with each other. Then, either the male screw or the female screw that has been driven to rotate backward is stopped, and is driven to rotate forward in the tightening direction.

Therefore, in the invention of the screw tightening device according to the first aspect, the male screw and the female screw are reversely driven in the direction of loosening the male screw or the female screw by the driving means while the male screw and the female screw are pressed by the pressing means. The vibration when the female screw reaches the screwing position and the respective screw threads collide is detected by the vibration sensor , and the signal is input to the driving means via the control means. Then, either the male screw or the female screw that has been reversely driven by the driving means is stopped, and the normal screw is driven in the tightening direction to start tightening the male screw and the female screw.
In the invention of the screw tightening device described in claim 2, the screwing position of the male screw and the female screw is determined based on the maximum vibration value detected every rotation of the male screw .

Furthermore, in the invention of the screw tightening method according to claim 3, the male screw and the female screw are engaged with each other as a state where the male screw and the female screw are pressed in the reverse direction in the direction of loosening either the male screw or the female screw. When the vibration at the moment when each screw thread hits is detected, either the male screw or the female screw that has been driven in reverse is stopped, and the male screw and the female screw are driven forward in the tightening direction. Tightening is started.

  According to the present invention, the screw tightening device that can smoothly start the screwing of the male screw and the female screw and prevent the biting of both by detecting the screwing start position of the male screw and the female screw with high accuracy. And a screw tightening method can be provided.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to FIGS.
A screw fastening device 1 according to an embodiment of the present invention is a device for fastening a bolt (male screw) 2 having a head 3 to a screw hole (female screw) 5 provided in a body 4 or the like, as shown in FIG. The cylinder (pressing means) 6 that presses the tip of the bolt 2 against the opening end surface of the screw hole 5 and the head 3 of the bolt 2 are gripped via the socket 7 and are driven to rotate forward in the direction in which the bolt 2 is tightened. The nut runner (driving means) 8 that is reversely driven in the loosening direction, the tip of the bolt 2 and the opening end surface of the screw hole 5 reach the screwing position, and the thread 2a located at the tip of the bolt 2 (see FIG. 3). ) And the screw thread 5a (see FIG. 3) located on the opening end face of the screw hole 5, and the vibration sensor 9 for detecting the vibration and the drive shaft 8a of the nut runner 8 are driven in the reverse direction. Sensor 9 A controller that drives the drive shaft 8a of the nut runner 8 to rotate forward when a vibration is detected when the screw thread 2a positioned at the tip of the screw 2 and the screw thread 5a positioned at the opening end surface of the screw hole 5 collide with each other. Control means) 10.

Reference numeral 11 in FIG. 1 indicates a slide unit. The slide unit 11 includes a substantially U-shaped frame body 12, a distal end portion of the upper plate portion 12 a and a distal end portion of the lower plate portion 12 b of the frame body 12. And a slider 14 slidably connected to a guide shaft 13 extending in the vertical direction.
The slider 14 is formed of a cylindrical body and is slidable in the vertical direction along the guide shaft 13. A fixing plate 16 to which the nut runner 8 is fixed is extended from one side surface opposite to the frame body 12 at the upper portion of the slider 14. The fixing plate 16 is formed with an insertion hole 16a through which a drive shaft 8a protruding from the nut runner 8 is inserted. Further, a vibration sensor 9 is attached in the vicinity of the nut runner 8 on the bottom surface of the front end portion of the fixed plate 16.
In addition, a cylinder 6 is placed on the lower plate portion 12 b inside the frame body 12, and an upper end of a cylinder rod 6 a that expands and contracts by driving of the cylinder 6 is connected via a connecting member 20 provided horizontally. It is connected to the other side of the slider 14.

As shown in FIG. 1, the nut runner 8 is fixed to the bottom surface of the fixed plate 16 of the slide unit 11, and the drive shaft 8 a of the nut runner 8 is inserted through the insertion hole 16 a of the fixed plate 16 to fix the fixed plate 16. It protrudes upward from. One end of the socket 7 is attached to the tip of the drive shaft 8a. The head 3 of the bolt 2 is detachably held at the other end of the socket 7.
The nut runner 8 has a drive shaft 8a that can be driven to rotate in the forward and reverse directions, and is driven by the controller 10 with its rotational drive direction, rotational speed, rotational angle, and rotational torque controlled.

As shown in FIG. 1, the controller 10 is electrically connected to each of the vibration sensor 9, the nut runner 8, and the cylinder 6.
The controller 10 controls the rotational drive direction, rotational speed, rotational angle, and the like of the drive shaft 8a of the nut runner 8, and selectively selects the rotational drive direction of the drive shaft 8a based on a signal from the vibration sensor 9. It can be controlled. Further, the controller 10 also controls a tightening torque for managing a tightening state of the bolt 2 in the screw hole 5.
Further, the controller 10 also controls the driving of the cylinder 6 and controls the raising / lowering of the cylinder rod 6 a and the pressing force applied to the opening end surface of the screw hole 5 by the tip of the bolt 2.

Next, a screw tightening method using the screw tightening device 1 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 3 and also to a control flowchart of the controller 10 shown in FIG. While explaining.
First, the present invention is set at a predetermined position so that the axis of the bolt 2 held by the nut runner 8 via the socket 7 is aligned with the axis of the screw hole 5 provided in the body 4. The screw fastening device 1 according to the embodiment is arranged.
Next, the screw tightening device 1 according to the embodiment of the present invention is operated, and a signal is input from the controller 10 to the cylinder 6. Then, the cylinder rod 6a is extended, and the slider 14 is lifted, and the tip of the bolt 2 is pressed against the opening end surface of the screw hole 5 (corresponding to S1 in FIG. 4).
Next, a signal is input from the controller 10 to the nut runner 8, and the drive shaft 8a of the nut runner 8 is reversely driven in a loosening direction, and the bolt 2 rotates in the same direction (corresponding to S2 in FIG. 4).

In the state described above, the vibration value detected by the vibration sensor 9 is always input to the controller 10. At this time, the vibration waveform detected by the vibration sensor 9 is as shown in FIG. 2, and the vibration value becomes maximum every rotation (360 °). As shown in FIG. 3 (b), the maximum vibration value is a screw thread located at the tip of the bolt 2, as shown in FIG. 3 (b). The vibration at the time when one side surface of the raised portion 2a collides with one side surface of the screw thread 5a located on the opening end surface of the screw hole 5 is detected. Thus, when the vibration value detected by the vibration sensor 9 is maximized, the tip of the bolt 2 is in a position where it is screwed into the opening end surface of the screw hole 5.
Then, the controller 10 determines whether or not the vibration value input from the vibration sensor 9 is larger than a predetermined vibration value (reference value) (corresponding to S3 in FIG. 4). When it is determined (corresponding to Yes in S3 in FIG. 4), the signal is output to the nut runner 8, and the drive shaft 8a that has been driven in reverse is stopped (corresponding to S4 in FIG. 4) and tightening direction. Is rotated forward (corresponding to S5 in FIG. 4), and tightening of the bolt 2 into the screw hole 5 is started.
When the controller 10 determines that the vibration value input from the vibration sensor 9 is smaller than the predetermined vibration value (corresponding to No in S3 in FIG. 4), the drive shaft 8a of the nut runner 8 is The state of reverse driving is maintained.

Next, after the front end of the bolt 2 is smoothly screwed into the opening end surface of the screw hole 5, the drive shaft 8a of the nut runner 8 is controlled to a predetermined rotational speed by the controller 10 and is driven to rotate forward. 6 is also maintained, the cylinder rod 6a is raised, and the bolt 2 is tightened in the screw hole 5. At this time, the controller 10 determines whether or not the drive shaft 8a of the nut runner 8 is tightened within a predetermined torque range (corresponding to S6 in FIG. 4), and is tightened within the predetermined torque range. When the time (corresponding to Yes in S6 in FIG. 4), the process proceeds to the determination of whether or not the predetermined tightening rotation range in the next step has been reached (corresponding to S8 in FIG. 4), and tightening within the predetermined torque range If not (corresponding to No in S6 in FIG. 4), the process proceeds from the next step of tightening NG (corresponding to S9 in FIG. 4) to the completion of tightening (corresponding to S14 in FIG. 4) and ends. Further, the controller 10 determines whether or not a predetermined time range has been entered (corresponding to S7 in FIG. 4). If the controller 10 has entered the predetermined time range (corresponding to Yes in S7 in FIG. 4), The process proceeds to the next step for determining whether or not the predetermined tightening rotation range has been reached (corresponding to S8 in FIG. 4), and when it does not fall within the predetermined time range (corresponding to No in S7 in FIG. 4). Then, the process proceeds from the next step of tightening NG (corresponding to S13 in FIG. 4) to the completion of tightening (corresponding to S14 in FIG. 4) and ends.
When the determination of whether or not the predetermined torque range has been reached (corresponding to S6 in FIG. 4) and the determination of whether or not the predetermined time range (corresponding to S7 in FIG. 4) is Yes, predetermined tightening Proceeding to the determination of whether or not the rotation range has been reached (corresponding to S8 in FIG. 4), and entering the predetermined tightening rotation range (corresponding to Yes in S8 in FIG. 4), tightening in the next step The process proceeds from OK (corresponding to S11 in FIG. 4) to completion of tightening (corresponding to S14 in FIG. 4) and ends. On the other hand, when it does not enter the predetermined tightening rotation range (corresponding to No in S8 in FIG. 4), tightening is completed from the next step of tightening NG (corresponding to S12 in FIG. 4) (S14 in FIG. 4). To the end).

As described above, according to the embodiment of the present invention, the bolt 2 is gripped on the drive shaft 8a of the nut runner 8 through the socket 7 and pressed against the screw hole 5 while being reversely driven in the loosening direction. The vibration sensor 9 detects vibration when one side surface of the screw thread 2a located at the tip of the bolt 2 collides with one side surface of the screw thread 5a located at the opening end surface of the screw hole 5. The screwing start position between the tip of the bolt 2 and the opening end surface of the screw hole 5 is detected.
Thus, the screwing start position can be detected with higher accuracy and more accurately than in the conventional configuration in which the displacement amount of the bolt 2 is detected and the screwing start position of the bolt 2 and the screw hole 5 is detected. If the tightening of the bolt 2 is started, the engagement between the bolt 2 and the screw hole 5 is prevented, and the bolt 3 is normally tightened into the screw hole 5.

Further, according to the embodiment of the present invention, even if the axial center of the bolt 2 is arranged with a slight inclination (about 2.5 degrees at the maximum) with respect to the axial center of the screw hole 5, the bolt 2 The screwing start position between the front end of the screw and the opening end surface of the screw hole 5 is reliably detected, and the bolt 2 is normally tightened to the screw hole 5.
Moreover, the screw tightening device 1 according to the embodiment of the present invention has a simplified configuration, and detects vibration when the screw thread 2a of the bolt 2 and the screw thread 5a of the screw hole 5 collide. Thus, since the screwing start position of the bolt 2 and the screw hole 5 is detected, the pitch of the screw portion is small, and the present screw tightening device 1 is installed in various places, and the installation conditions are changed each time. Even in this case, the detection of the screwing start position between the bolt 2 and the screw hole 5 does not become difficult, and versatility is enhanced. Further, the present screw tightening device 1 can be operated by being incorporated in a robot working in a vehicle assembly process, for example.
The screwing start position may change depending on the type of screw (shape). However, according to the embodiment of the present invention, the vibration sensor 9 causes the tip of the bolt 2 and the opening end surface of the screw hole 5 to be changed. Is detected, the rotation of the bolt 2 in the reverse rotation direction is stopped, the rotation is stopped at an angle A in the reverse rotation direction (loosening direction) from that position, and the forward rotation direction (tightening direction) from that position is stopped. Tightening can be started by rotating. The above-described angle A may be determined in advance by experiment for each type of screw.

  Moreover, in the screw fastening apparatus 1 which concerns on embodiment of this invention, although the form which fastens the volt | bolt 2 to the screw hole 5 provided in the body 4 was demonstrated, when screw parts, such as the volt | bolt 2 and a nut, are fastened. Can also be used.

FIG. 1 is a side view showing a screw fastening device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a vibration waveform detected by a vibration sensor which is a configuration of the screw tightening device according to the embodiment of the present invention. 3 is an enlarged view of part A in FIG. 1, (a) shows immediately before the screw thread at the tip of the bolt collides with the screw thread at the open end face of the screw hole, and (b) shows the moment when the collision occurs. It is sectional drawing. FIG. 4 is a control flow diagram of the controller which is the configuration of the screw tightening device according to the embodiment of the present invention.

Explanation of symbols

1 Screw tightening device, 2 bolt (male screw), 2a thread, 5 screw hole (female thread), 5a thread, 6 cylinder (pressing means), 8 nut runner (driving means), 8a drive shaft, 9 vibration sensor , 10 Controller (control means)

Claims (3)

In the screw tightening device that tightens the male screw and the female screw,
A pressing means for pressing the male screw and the female screw;
A driving means for driving the male screw or the female screw to rotate in the forward direction in the direction of tightening, and to drive in the reverse direction in the direction of loosening;
A vibration sensor and the said external thread internal thread when it reaches the engaged position, detects the vibration at the time of the thread of the male screw and the female screw has collided,
When either the male screw or the female screw is driven in reverse by the driving means, and the vibration sensor detects a vibration due to a collision of each thread of the male screw and the female screw, the male screw or the female screw Control means for driving one of the above in the normal direction by the drive means;
A screw fastening device comprising: The screw tightening device according to claim 1, wherein the control means determines a screwing position of the male screw and the female screw based on a maximum vibration value detected every rotation of the male screw. . In the screw tightening method of tightening the male screw and the female screw,
While the male screw and the female screw are pressed, the male screw and the female screw reach a screwing position in a state where the male screw and the female screw are reversely driven in a loosening direction, and the male screw and the female screw A screw tightening method comprising: stopping at least one of the male screw or the female screw that has been reversely driven at the time of detecting vibration when each screw thread collides, and forwardly driving in a tightening direction.

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