JPH0112928Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is based on a multi-axis nut runner mechanism in which a plurality of nut runners for tightening nuts are rotatable and protrude in parallel. The present invention relates to a multi-axis nut runner device with a rotary indexing mechanism, which includes a rotary indexing mechanism section that integrally rotates the plurality of nut runners to index the position of each nut runner.

(Prior art) On assembly lines for mass-produced products, multi-shaft nut runners are used to tighten multiple nuts at the same time in order to streamline the tightening work of nuts. When tightening six bolts that occupy equally spaced positions, if the six bolts are placed close to each other, the six nut runners must be connected to a common support member to tighten them simultaneously. A situation arises in which it becomes difficult to use a six-axis nut runner device that protrudes from the base due to space limitations.

In such a case, for example, a two-shaft or three-shaft nut runner device equipped with two or three nut runners may be used to perform the tightening work of six bolts in two or three times. Measures will be taken. For example, when tightening six bolts in this way, as shown in Fig. 1, each nut runner A, B, and C of the three-axis nut runner device first tightens every other bolt out of the six bolts. Tighten the bolts for the first time. Next, when the tightening work for these three bolts is completed, in order to perform the second tightening work for the remaining three bolts, the nut runners A, B, and C are rotated together, for example, in the direction of the arrow p in the figure. Let me,
Position indexing is performed to move nut runners A, B, and C to the respective positions of the remaining three bolts. The position index for tightening the remaining three bolts can be determined by, for example, locking pieces provided on the common support member for nut runners A, B, and C being placed at predetermined positions on the fixed part of the three-axis nut runner device. This is done by being locked to a stopper. After that, the remaining three bolts are tightened a second time, and all six bolts are tightened.

In such a case, the position indexing performed before the second tightening would ideally allow the nutrunner A,
B and C are 3 to be tightened as shown in Figure 2 at the beginning of the second tightening operation.
For example, if the workpiece to which six bolts are to be tightened is rotatably supported, such as an automobile engine flywheel. Even if proper position indexing is performed, the positions of nut runners A, B, and C are misaligned with respect to each of the remaining three bolts to be tightened, and when the second tightening operation is started, , the nut runners A, B, and C may not properly engage each of the three bolts. The cause of this is
Acting integrally on the nut runners A, B and C during the first tightening operation, e.g. along the individual rotation directions of the nut runners A, B and C, opposite to arrow p in FIG. It is in the torsion couple of. Due to the action of this torsional couple, the positions of the tips of the nut runners A, B, and C that engage with the respective bolts are slightly moved in the direction opposite to the arrow p in FIG. At this time, since the workpiece to which the bolt is tightened is rotatable, the nut runners A, B, and C that receive this torsional couple rotate slightly in the direction opposite to the arrow p in Figure 1. do. When the first tightening is completed, the nut runners A, B, and C are disengaged from the three bolts. Due to the torsional stress accumulated by the torsional couple received therein, it suddenly returns to the direction of the arrow p in FIG. however,
At this time, the workpiece to which the bolt is tightened remains in the same state as it was at the end of the first tightening operation, so after the nut runners A, B, and C are rotated together and position indexing is performed, At the start of the second tightening work, nut runners A and B
and C will result in a relative positional shift with respect to the bolt to be tightened, resulting in a position as shown by the two-dot chain line in FIGS. 1 and 2.

One of the causes of the generation of torsional stress acting on the nut runners A, B, and C is that the tightening torque and tightening completion time of each of the nut runners A, B, and C do not match.
That is, if the bolt tightening process by each nut runner A, B, and C is expressed by taking the torque T on the vertical axis and the tightening time t on the horizontal axis, for example, the third
As shown by broken lines A', B' and C' in the figure, the respective processes are different. here the torque
The distance between Ta and Tb is set as the standard tightening torque for bolts by nut runners A, B and C, and nut runners A, B and C calculate the difference between ΔT ₁ , ΔT ₂ and ΔT ₃ in the final tightening torque. This also causes a difference between Δt ₁ , Δt ₂ and Δt ₃ in the tightening completion time. Due to these mutual differences, the torque components of one or two of the nut runners A, B, and C become a torsional couple that acts integrally on the nut runners A, B, and C. and causes torsional stress to be accumulated in C.

In this way, when a conventional multi-axis nut runner device performs position indexing and tightens a large number of nuts in multiple steps, it is difficult to There is an inconvenience that a positional shift may occur between the nut runner and the nut runner.

(Purpose of the invention) In view of the above, the present invention provides a multi-axis nut runner mechanism having a plurality of nut runners and a rotary indexing mechanism that rotates the plurality of nut runners integrally to index the position of each nut runner. Equipped with a
For example, if the number of nuts placed on a rotatably supported workpiece is greater than the number of nut runners,
Even when the position of the nut runner is determined and the tightening work is performed in multiple steps, proper tightening can be performed without any positional deviation between the nuts and the nut runner at each tightening work stage. It is an object of the present invention to provide a multi-shaft nut runner device with a rotary indexing mechanism.

(Structure of the invention) The multi-shaft nut runner device with a rotary indexing mechanism according to the invention includes a plurality of nut runners each having a rod-like shape and having an engaging portion that engages with a nut member at the tip. A multi-shaft nut runner mechanism part that rotatably protrudes from the member so as to occupy mutual positions arranged at equal pitches on the circumference, a nut runner drive part that rotates each of the nut runners, and a multi-shaft nut runner mechanism. A rotary indexing mechanism section that indexes the positions of a plurality of nut runners by rotating a supporting member of the section in a direction perpendicular to the protruding direction of each nut runner, and a rotary indexing mechanism section that indexes the positions of the plurality of nut runners, and a rotary indexing mechanism section that indexes the positions of the plurality of nut runners by rotating a supporting member of the section in a direction perpendicular to the protruding direction of each nut runner. The structure includes an approaching/separating drive unit that relatively approaches and separates the nut runners from the workpiece, and a control unit that controls the operation of the rotation indexing mechanism unit described above. After each nut runner engages the engaging portion with the nut member of the workpiece and tightens the nut member of the workpiece, the nut runner rotates while the engaging portion is engaged with the nut member of the workpiece. The indexing mechanism section rotates the support section of the multi-axis nut runner mechanism section in a first direction that eliminates torsional stress in each nut runner to a predetermined position, and then rotates the supporting section of the multi-axis nut runner mechanism section again in a second direction opposite to the first direction. Then, while the plurality of nut runners are spaced apart from each other relative to the workpiece, the plurality of nut runners are rotated to a predetermined position in the first or second direction to adjust the position of the plurality of nut runners. It is assumed that an action for performing indexing is performed.

With this configuration, when a plurality of nut members of a rotatably supported workpiece are tightened in multiple steps by indexing the position of the nut runner, the position of the nut runner is tightened after the position of the nut runner is determined. It is possible to correctly correspond to the position of the nut member to be used, and proper tightening can be performed at each tightening work stage.

(Example) Hereinafter, an example of the present invention will be described with reference to FIG. 4 and subsequent drawings.

4 and 5 show the structure of a tightening unit forming an example of a multi-axis nut runner device with a rotary indexing mechanism according to the present invention, together with a work to be tightened by this tightening unit, and FIG. The figure is a side view, and FIG. 5 is a front view.
In FIGS. 4 and 5, 1 is a workpiece mounting table, and 2 is a workpiece lifter that raises and lowers the workpiece mounting table 1. As shown in FIG. An engine E is mounted and fixed on the workpiece mounting table 1, and a flyhole F is connected to the crankshaft S of the engine E.
Six bolts V for tightening are temporarily tightened at positions arranged at equal pitches on a common circumference. In this case, the flyhole F and the crankshaft S are indexed in advance so that a specific cylinder is at the top dead center position, and are rotatably supported. And fly hole F
A tightening unit 3 is arranged on the base 5 so as to face the tightening unit 3.
has three nut runners 4A, 4B, and 4C, each of which can perform tightening work independently.

A guide rail 6 is provided on the base 5, and a slide table 7 can slide on this guide rail 6 in the left-right direction in FIG.
In addition, the base 5 is located at the rear of the tightening unit 3.
A cylinder 9 for advancing and retracting the tightening unit 3 is held by a bracket 8 fixed to the bracket 8 . A piston rod 9a extends from the reciprocating cylinder 9, and the tip of the piston rod 9a is connected to a block 10 fixed to the slide table 7. The advancing/retracting cylinder 9, the piston rod 9a, etc. form a contact/separation driving section.

A fixed base plate 11 that stands up vertically is fixed to the slide table 7, and guide rails 12 are vertically disposed at both ends of the front surface of the fixed base plate 11.
and guides vertical movement of the movable substrate 13. The movable base plate 13 has a protruding piece 15, to which the tip of a piston rod 16a extending from an elevating cylinder 16 whose rear end is fixed to the slide table 7 is connected. Pin 1 is attached to the movable board 13 at three locations.
9 is planted, and a roller 20 is attached to this pin 19.
is rotatably attached, and the rotating board 21
I support 3 points. In addition, the guide plate 22
is fixed to the movable base plate 13 with screws 23, and the position of the rotary base plate 21 in the horizontal direction is regulated by the guide plate 22.

Further, a position indexing cylinder 28 is attached to the movable base plate 13 by a support pin 26 , and the tip end of the position indexing cylinder 28 connects to a pin 27 that protrudes from the rotary base plate 21 . A pivoted piston rod 28a protrudes. The rotation base plate 21 is guided by the rollers 20 and rotated by the expansion and contraction of the piston rod 28a. The position indexing cylinder 28, piston rod 28a, etc. form a rotation indexing mechanism.

The rotating base plate 21 has an overall rod shape that protrudes from one surface thereof so as to be rotatable at positions arranged at equal pitches on the circumference around the center of rotation. 3 Natsutranna 4A, 4B
and 4C, and three drive units 30A, 30B and 4C protrude from the other side, occupying positions equally spaced on the circumference around the rotation center. We support each of the 30C. Therefore, nutrunner 4A, 4
B and 4C, and drive units 30A and 30B
and 30C are both configured to rotate around the center of rotation of the rotary base plate 21 as the rotary base plate 21 rotates.

The drive units 30A, 30B and 30C are
The respective tightening rods 31 of the nut runners 4A, 4B and 4C are rotationally driven. In addition, the nut runners 4A, 4B and 4C are connected to the socket 32.
A, 32B, and 32C are provided, and each of these sockets 32A, 32B, and 32C is formed with an engaging portion 33 that fits into the head of the bolt V at its tip. Then, the rear ends of the sockets 32A, 32B and 32C are engaged with the tightening rod 31 via the pin 34,
The sockets 32A, 32B and 32C are rotatably driven by the rotation of the respective tightening rods 31. The pin 34 is fitted at the tip of the tightening rod 31 so as to be able to slide in the axial direction thereof.
B and 32C are movable in their axial directions, and a coil spring 31a surrounding the tightening rod 31 moves the sockets 32A and 32C.
The sockets 32A, 32B, and 32C are compressed at the rear end portions of the sockets 2B and 32C, and bias the sockets 32A, 32B, and 32C toward their tips.

Further, a bottomed cylindrical support frame 35 is provided, and a base plate 35a and a support plate 35b are fixed to both ends of the support frame 35. This base plate 35a is attached to the rotating board 21 with bolts 36.
The support plate 35b is fixed to the sockets 32A, 32B and 3 through the bush 37.
It is configured to support 2C. These support frame 35, rotating board 21 and nut runner 4
A, 4B, 4C, etc. form a multi-shaft nut runner mechanism section. An engaging piece 41 is fixed on the rotary base plate 21, and is attached at an angle of approximately 60° on the circumference of the movable base plate 13 around the center of rotation of the rotary base plate 21. At separated positions, stoppers 42 and 4 have adjustment bolts 42a and 43a whose heads abut against the engagement piece 41.
3 is installed protrudingly.

The tightening unit 3, which forms an example of the multi-shaft nut runner device with a rotary indexing mechanism according to the present invention and configured as described above, is controlled by a control system provided therewith.

FIG. 6 is a block diagram equivalently showing an example of the control system of the tightening unit 3, and this control system is
The above-mentioned lifting cylinder 16, advancing and retreating cylinder 9,
Position indexing cylinder 28 and drive unit 30
A, 30B, and 30C send out control signals for performing necessary operations, and further send out control signals to control the above-mentioned work lifter 2,
Controller 50 that obtains information from work lifter 2
It is formed with

When the tightening unit 3 tightens the six bolts V for fixing the flyhole F to the crankshaft S of the engine E, the engine E is first transported to the workpiece mounting table 1 by a transport means (not shown). When the work lifter 2 is loaded and placed, the controller 50 supplies the work lift signal Sa to the work lifter 2 to operate the work lifter 2, raise the engine E, and stop it at a predetermined tightening work position. On the other hand, a height detection signal Sb representing the height of the engine E at that time is sent from the work lifter 2 to the controller 50, and based on this height detection signal Sb, the vertical shift position of the tightening unit 3 is determined. The controller 50 supplies the lifting cylinder 16 with an lifting control signal Cd corresponding to the determined vertical shift position. As a result, when the position of the multi-axis nut runner mechanism of the tightening unit 3 is lower than the normal tightening position of the bolt V, the lifting cylinder 16 protrudes the piston rod 16a, raises the movable base plate 13, and tightens the nut runner. If the position of the multi-axis nut runner mechanism of the unit 3 is higher than the normal tightening position of the bolt V, the piston rod 16a is pulled back and the movable base plate 13 is lowered.

In this way, the vertical tightening unit 3
Once the shift position is set, the controller 50 then supplies an advance/retreat control signal Ce to the advance/retreat cylinder 9 in order to gradually advance the tightening unit 3 toward the engine E in order to perform the first tightening operation. As a result, the advancing/retracting cylinder 9 operates to project the piston rod 9a, the slide table 7 slides on the guide rail 6, and the tightening unit 3 moves forward. At this time, tightening unit 3
The engagement piece 41 is in contact with the stopper 42, and the nut runners 4A, 4B, and 4C are in the tightening position with respect to the bolt V, and the sockets 32A, 32B, and 32C of the nut runners 4A, 4B, and 4C are in a state where they are in a tightening position with respect to the bolt V. The engaging portions 33 fit into the corresponding bolts V, respectively. In this state, the controller 50 controls the drive units 30A, 30B, and 3.
At the same time, nut runner drive signal to each of 0C
Ca, Cb and Cc are supplied to the drive unit 30.
A, 30B and 30C are activated and the socket 32
A, 32B and 32C are rotated, for example, in the right direction, through the corresponding tightening rods 31 to tighten the bolts V. After the bolt V is tightened to the specified tightening torque,
The operation of drive units 30A, 30B and 30C is stopped.

In the tightening work of the bolts V by the nut runners 4A, 4B and 4C, there are mutual differences in the final tightening torque and tightening completion time for each bolt V of the nut runners 4A, 4B and 4C. As a result, Natsutranna 4A,
The tips of 4B and 4C, that is, the sockets 32A,
The engaging portions 33 of 32B and 32C are connected to the rotating base plate 21.
twist against the side, at this time the sockets 32A, 32
Since B and 32C and the bolt V are in a fitted state, they shift from their normal positions along with the bolt V, and torsional stress is accumulated at the tips of the nut runners 4A, 4B and 4C. This nut runner 4A, 4B and 4C
An indexing control signal Cf is supplied from the controller 50 to the position indexing cylinder 28 in order to release the torsional stress accumulated at the tip of the cylinder 28 . As a result, the piston rod 28a of the position indexing cylinder 28 is retracted from the state shown in FIG. The engagement piece 41 is brought into contact with the adjustment bolt 43a of the stopper 43 as shown by the chain line. As a result, Natsutranna 4A, 4B
and 4C is also rotated in the left direction, which is the direction in which the torsional stress accumulated at the tip thereof is released, and the torsional stress is eliminated. Next, the controller 50 sends an index control signal Cf to return the bolt V to the home position.
is supplied to the position indexing cylinder 28, the piston rod 28a is projected, and the rotating base plate 21 is rotated to the right (counterclockwise in FIG. 5).

Thereafter, in order to cause the tightening unit 3 to perform the second tightening operation, the controller 50 supplies the advance/retreat control signal Ce to the advance/retreat cylinder 9, moves the tightening unit 3 backward, and tightens the bolts V and sockets 32A, 32B, and 32C. Unmating. Next, in order to move the nut runners 4A, 4B and 4C to the tightening positions of the remaining three bolts V,
The indexing control signal Cf is sent to the position indexing cylinder 28.
supply to. As a result, the position indexing cylinder 2
8, the rotating base plate 21 is connected to the stopper 4 by the engaging piece 41.
Rotate it until it touches the adjustment bolt 43a of No. 3,
The positions of the nut runners 4A, 4B, and 4C are determined for the second tightening operation.

In this state, the controller 50 again supplies the advance/retreat control signal Ce to the advance/retreat cylinder 9 to advance the tightening unit 3 and tighten the sockets 32A, 32.
The engaging portions 33 of B and 32C are fitted to the remaining three bolts V, and the drive units 30A and 30B are assembled.
and 30C, respectively, to the nut runner drive signal Ca,
Supply Cb and Cc to sockets 32A, 32B
and 32C to tighten the remaining three bolts V. When the tightening work of these three bolts V is completed, the tightening work of the six bolts V is completed, so the multi-shaft nut runner mechanism section and the tightening unit 3 are returned to their original positions, that is, the first tightening work described above. Return to the position before the start.

The manner of control by the controller 50 that controls the operation of the tightening unit 3 as described above can be summarized as a flowchart as shown in FIG. Since the contents of each step in this flowchart are as described above, repeated explanation will be omitted.

(Effects of the Invention) As is clear from the above description, the multi-axis nut runner device with a rotary indexing mechanism according to the present invention allows the position indexing of the nut runner to move a plurality of nuts of a rotatably supported workpiece. When tightening the nuts in multiple stages, it is possible to prevent poor fitting due to misalignment between the nuts and the nut runner due to torsional stress generated in the multi-axis nut runner mechanism.
This problem can be effectively solved by using the rotary indexing mechanism used to index the position of the nut runner.
Therefore, there is an advantage that there is no need to provide a special work rotation prevention device, and there is no need to take measures to increase the structural strength of the multi-axis nut runner mechanism. Further, since the position of the nut runner after position indexing can be made to correspond correctly to the position of the nuts to be automatically tightened, automation in the assembly line of mass-produced products can be more effectively promoted.

[Brief explanation of the drawing]

Figures 1 to 3 are diagrams used to explain the misalignment between the nut runner and nuts when the nut runner tightens the nuts, and Figure 4 is an example of the multi-axis nut runner device with a rotary indexing mechanism according to the present invention. 5 is a front view of the tightening unit shown in FIG. 4, and FIG. 6 is a control system of the tightening unit shown in FIGS. 4 and 5. FIG. 7 is a flowchart summarizing the control mode by the controller shown in FIG. 6. In the figure, 3 is a tightening unit, 4A, 4B and 4C are nut runners, 9 is a cylinder for advancing and retracting, and 16
21 is a rotating board, 28 is a position indexing cylinder, 30A, 30B and 30C are drive units, 32A, 32B and 32C are sockets, 33 is an engaging portion, and 50 is a controller.

Claims (1)

[Scope of utility model registration request] A plurality of nut runners each having a rod-like shape and having an engaging portion that engages with the nut member are disposed at the tip.
a multi-shaft nut runner mechanism part rotatably protruding from a common support member so as to occupy mutually equidistant positions on the circumference; and a nut runner drive part for rotating each of the plurality of nut runners. a rotary indexing mechanism section that indexes the positions of the plurality of nut runners by rotating the support member in a direction perpendicular to the protruding direction of each of the plurality of nut runners; a approaching/separating drive unit that relatively approaches and separates from the workpiece supported by the workpiece; and the plurality of nut runners are brought relatively close to the workpiece, and each of the plurality of nutrunners moves the engagement part toward the workpiece. After the nut member of the workpiece is engaged with the nut member of the workpiece and the nut member of the workpiece is tightened, the support member is rotated to a predetermined position in a first direction that eliminates the torsional stress in each of the plurality of nut runners, and then rotated again in a second direction opposite to the first direction to return to the original position, and then , while the plurality of nut runners are spaced apart from each other relative to the workpiece, the supporting member is moved to the first or second nut runner.
A multi-axis nut runner device with a rotary indexing mechanism, comprising: a control means for rotating the plurality of nut runners to a predetermined position in the direction of , and performing an operation for position indexing the plurality of nut runners.