JPH0691450A - Thread fastening equipment - Google Patents

Abstract

PURPOSE:To reduce bolt fastening work time for one work by providing a handling means having a hand for holding nut runners and for traveling the nut runners corresponding to a thread fastening work site for thread fastening work between many positioning reference parts. CONSTITUTION:A fixture plate 6 is provided above a work W. Two nut runners 8A, 8B are detachably mounted on the fixture plate 6 by the engagement of locating pins with locating holes 18a, 18b-31a, 31b. While one nut runner 8A is in bolt fastening work, the other nut runner 8B is moved to the next bolt fastening work site by means of a handling robot 13. This action is alternately repeated to each nut runner 8A, 8B. The result reduces cycle time until the whole work has been completed for one work W.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw tightening device for performing a screw tightening operation on a large number of screw tightening operation parts on the same plane of a work to be screwed.

[0002]

2. Description of the Related Art For example, as shown in FIG. 7, a bolting operation by a robot has been tried as a part of automatic assembly of a transaxle case of an automobile. In this, the nut runner 53 is supported on the tip of the arm 52 of the articulated robot 51, and the bolt B is supplied from the parts feeder 54 through the hose 55 to the nut runner 53 and is conveyed by the conveyor 56. With respect to the transaxle case (work) W, ten or more bolts are automatically tightened around the entire circumference of the joint between the case body M and the cover S. The transaxle case W is fixed to the pallet 57 in advance.

[0003]

However, in the conventional screw tightening device as described above, a single nut runner 53 is used to tighten ten or more bolts B one by one. It takes a long time to complete all the bolt tightening for one work W, which is not preferable because the cycle time of the assembly line becomes long.

Further, since the arm 52, 58 of the robot 51 receives the reaction force in the rotation direction due to the tightening of the bolt B, the tightening torque of the bolt B is increased in consideration of the rigidity of the robot 51 itself. However, the tightening torque itself is restricted.

Further, as shown in FIG. 7, when bolts are tightened with a single nut runner 53 on the entire circumference of the cover S, the circle of the nut runner 53 is centered on the axial center of the nut runner 53. If the posture in the circumferential direction is constant, the root portion of the hose 55 for supplying bolts connecting the nut runner 53 and the parts feeder 54 to the nut runner 53 side may be the cover S depending on the bolt tightening work site. Interference may cause difficulty in automatic supply of the bolt B. In order to avoid such troubles, it is necessary to provide an actuator for changing the posture of the nut runner 53 in the circumferential direction according to the bolt tightening work site, which complicates the screw tightening equipment. This results in higher costs.

The present invention has been made in view of the above problems, and shortens the time required for screw tightening of a large number of screw tightening work parts and eliminates the restriction of tightening torque.
At the same time, an object of the present invention is to provide a screw tightening device that avoids interference between the screw supply hose and the work.

[0007]

According to the present invention, in an apparatus for performing a screw tightening operation on each of a large number of screw tightening operation parts, a fixture plate fixedly arranged above the work, and the fixture plate is provided with the above-mentioned fixture plate. A plurality of positioning reference parts individually formed for each screw tightening work part, and a positioning fitting part that can be fitted to the positioning reference part are provided. By having a plurality of nut runners that are detachably attached to the fixture plate by fitting the positioning fitting part to one of the positioning reference parts, and a hand that grips the nut runner, screw tightening work can be performed. According to the screw tightening work site to be performed, the nut runner is configured to be moved between a large number of positioning reference parts. It is.

[0008] Then, the screw tightening work site which each nut runner should take charge of is specified in advance for each nut runner. For example, in the example of the transaxle case illustrated above, when two nut runners are used to tighten the bolts around the joint between the case body and the cover, one nut is used to tighten the bolts around the circumference of the cover. Let the runner do the bolt tightening work for the other half turn on the other nut runner.

[0009]

According to this structure, during the screw tightening work of the specific nut runner, another nut runner is moved from the screw tightening work site where the screw tightening work is completed to the next screw tightening work site by the handling means. The same operation is repeated for each nut runner. As a result, it is possible to perform the screw tightening work of a specific nut runner and the moving operation of another nut runner in parallel, and it is possible to shorten the cycle time until all the screw tightening works for one work are completed. become able to.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1, 2 and 3 are views showing an embodiment of the present invention, and show an example of a screw tightening device in which a transaxle case of an automobile is a work to be screwed, as in FIG.

As shown in FIG. 1, a transaxle case (work) W, which is fixed to a pallet 1 in advance, is conveyed to a screw tightening work station S _T by a conveyor 2 and is temporarily stopped. At the tightening work station S _T , a large number (here, 14 places) of bolting work parts P _{1 to} P ₁₄ around the entire joint of the case body M and the cover S of the work W are bolted. It

A pedestal 3 and a parts feeder 4 are arranged side by side on the side of the conveyor 2, and from the pedestal 3 to the conveyor 2
A fixture plate 6 located right above the cover S is detachably fixed to the arm portion 5 extending to the side by a bolt 7. Then, two nut runners 8A and 8B are detachably attached to the fixture plate 6, and each nut runner 8 is attached.
A predetermined bolt B is supplied to A and 8B from the parts feeder 4 through a hose 9 for supplying a bolt.

On the other hand, as shown in FIG. 3, a pair of locate pins 11 are provided as a positioning fitting portion on the upper flange portion 10 of each nut runner 8A, 8B so as to project downward, and each nut runner 8A is also provided. , 8B has a flat surface 12 formed by cutting a part thereof.

On the gantry 3, a Cartesian coordinate type handling robot 13 is provided as a handling means. Arm 1 of this handling robot 13
At the tip of No. 4, each nut runner 8
A hand 16 is provided for gripping the neck portions 15 of A and 8B, and the handling robot 13 moves the nut runners 8A and 8B on the fixture plate 6 in accordance with the portion to be bolted. It has a function.

As shown in FIG. 2, the fixture plate 6 is in the form of a plate cam having a handle portion 17 formed integrally therewith, and the contour shape of the fixture plate 6 is a large number of bolt tightening operations in plan view of the work W. The shape is similar to the shape formed when the centers of the parts P _{1 to} P ₁₄ are connected by straight lines.

Further, the fixture plate 6 includes
For each of a number of bolting worksite P ₁ to P ₁₄ at a rate of two pair, the nut runner 8A, a number of locating holes 18a as a positioning reference portion corresponding-fitting the locating pin 11 of the 8B side, 18B～ 31a, 31b
Are formed. These locate holes 18a, 18b
～31A, bolts 31b, the nut runner 8A, when mated with the locating pin 11 of the 8B side, also applicable to the axis of the nut runner 8A or 8B in any bolting worksite P ₁ to P ₁₄ It is set so that the center of the tightening work portion coincides with each other, and the flat surface 12 of the body portion of the nut runners 8A, 8B contacts the outer peripheral surface of the fixture plate 6.

In the screw tightening device having such a structure, for example, as shown in FIG. 2, when the bolt tightening work is carried out at 14 places around the entire circumference of the joint part of the case W with the cover S of the case body M. , half of the bolts fastening the bolt tightening work site P ₁ to P ₇ was borne on one of the nut runner 8A, the other half bolting worksite P ₈ to P ₁₄
The movement locus and the like of the handling robot 13 is set in advance so that the other nut runner 8B is responsible for tightening the bolt.

When the work W conveyed by the conveyor 2 is positioned at the bolting work station S _T , the necks 15 of the nut runners 8A and 8B at the standby position (not shown) are connected to the hand 16 of the handling robot 13. It is grasped by and positioned on the fixture plate 6 in order. That is, one nut runner 8A is bolted by the handling robot 13 to the work portion P ₁
The nut pin 8A is moved to a position where the locate pin 11 is fitted into the corresponding locate holes 18a and 18b and positioned, and then the one nut runner 8A is released from the hand 16. Likewise moving the other of the nut runner 8B until bolting worksite P ₈ for positioning.

Thus, the bolt tightening work parts P ₁ , P ₈
To the nut runner 8A or 8B is positioned, the nut runner 8A, 8B to the supplied predetermined bolt B from the parts feeder 4 shown in FIG. 1, parallel in both bolting work site P _1, P ₈ Then bolting work is performed. At this time, each nut runner 8A, 8B
The reaction force in the rotation direction due to the tightening of the bolt B by the bolt B is transmitted to the fixture plate 6 through the locate pin 11 and is received by the stationary fixed fixture plate 6 and the pedestal 3. The tightening torque of is not particularly limited.

As described above, the bolt tightening work parts P ₁ , P ₈
While the bolts are being tightened by the handling robot 13, the handling robot 13 bolts the hand 16 to the bolting action portion P ₁
The nut runner 8A, which is tightening the bolt, is moved to a position above the nut runner 8A to stand by.

When the bolt tightening at the bolting work portions P ₁ and P ₈ is completed, the handling robot 13 grips one nut runner 8A that has been bolted at the bolt tightening work portion P ₁ and adjoins it. It is moved to the bolting work site P ₂ and positioned. Thus, when one of the nut runner 8A to the next bolt tightening operation site P ₂ is positioned, similarly bolting work and the supplied bolts B from the parts feeder 4 to the nut runner 8A is performed.

While one of the nut runners 8A is bolting at the bolting work site P ₂ , the handling robot 13 is the other nut runner of the bolting work site P _{8 where} the bolting work has been completed first. 8B is gripped and moved to the bolting work site P ₉ adjacent to it, and positioned. Then, as soon as the other nut runner 8B is positioned, the bolt B is removed from the parts feeder 4 immediately.
Is supplied, and the other nut runner 8B similarly performs bolting.

Thus, the two nut runners 8A,
8A, 8B, while one of the nut runners is performing the bolt tightening work, the other nut runner is moved from the position where the bolt tightening is completed to the next bolt tightening work site for each nut runner 8A, 8B. By alternately repeating the above, the one nut runner 8A bolts from the bolt tightening work portion P ₁ to the bolt tightening work portion P ₇ , and similarly, the other nut runner 8B.
Is from the bolting work portion P ₈ to the bolting work portion P ₁₄
Will be tightened up to the bolt.

Then, the respective bolt tightening work parts P _{1 to} P ₁₄
When tightening the bolts with the nut runners 8A and 8B, as shown in FIGS.
Side bolt supply port 3 at the root of the hose 9 for supplying bolts
By setting the postures of the nut runners 8A and 8B in advance so that 2 always points out of the fixture plate 6, the hose 9 for supplying the bolt and the work W are provided.
It is possible to avoid interference with.

As described above, the nut runner 8A,
When moving 8B, the nut runners 8A and 8B
Of the outer peripheral end surface 10 of the fixture plate 6
By moving the nut runners 8A and 8B while sliding them in contact with 0 (see FIG. 3), the nut runners 8A and 8B are prevented from tilting or rotating around the vertical axis, and the posture thereof is regulated to the optimum posture. can do. As a result, the hose 9 for supplying the bolt can be controlled so as to be directed in a specific direction to prevent the hose 9 from interfering with the work W or twisting, and also locate pin 11 and locate hole 1.
8a, 18b-31a, 31b can be easily inserted and fitted.

As described above, the bolt tightening work parts P _{1 to} P
_When the bolt tightening for all of ₁₄ is completed, the nut runners 8A and 8B are returned to the origin position (not shown) by the handling robot 13, and the work W is exchanged at the bolt tightening work station S _T during that time.

As described above, according to this embodiment, one handling robot 13 is used to handle a plurality of nut runners 8A,
By performing bolting work while moving 8B,
A large number of bolt tightening operations can be performed efficiently.

Here, when the work (transaxle case) W to be bolted is changed to another specification, the fixture robot is changed along with the trajectory data of the handling robot 13. This is dealt with by replacing the chaplate 6. In addition, in the present embodiment, an example in which a plurality of bolt positions to be tightened are all on the same plane has been described, but the present invention is not necessarily limited to this, and bolts The same can be applied to the case where is slightly offset in the vertical direction.

The work (transaxle case) W, which is bolted to the case body M and the cover S as described above, is mated with the joint surface 33 (see FIG. 7) in the subsequent step as shown in FIG. After being abutted with the side part C, it is fastened and integrated with the counterpart part C by the four bolts 35 inserted from the bolt receiving part 34 (see FIG. 7). Since the space of the portion 34 is small, it becomes a narrow space work and the bolt tightening work by the commercially available air-driven ratchet wrench W _R is troublesome, so the bolt tightening is performed by using the automatic tightening device as shown in FIGS. Work shall be performed.

That is, in the automatic tightening device, the four frames 38 are radially fixed to the substantially bow-shaped fixture 36 via the locate pins 37, and the commercially available ratchet wrench W _R and rodless type are mounted on each frame 38. And the ratchet wrench W _R of the air cylinder 39 is provided separately.
Are linked to. And each ratchet wrench W
_{The R} can rotate while being guided by the guide roller 42 and the guide groove 43 with the fulcrum of the ratchet gear 41 as the center of rotation. The ratchet wrench W _R runs idle in the direction of arrow a, and the predetermined tightening work is performed only when rotating in the direction of arrow b.

In order to perform the bolt tightening work using the automatic tightening device having the above-described structure, first, the handle 45 suspended by the wire 44 of the balancer (not shown) is pulled down to fix the fixture 36. The locating pin 47 is fitted to a fixed guide 48 while being lowered downward around a fulcrum portion 46 between the supporting body 45 and the support body 45.
The handle 45 is fixed to the fixture 36 in advance.

Then, the ratchet gear 41 of each ratchet wrench W _R is fitted to the head of the bolt 35 which is temporarily inserted in advance in the bolt receiving portion 34 shown in FIG. 4, so that they are completely fitted together. Ratchet wrench W _R
Drive slightly. At this time, each ratchet wrench W
_R is at the position shown by the phantom line in FIG. 6 with respect to the frame 38.

When the bolt 35 and the ratchet gear 41 are securely fitted to each other as described above, each ratchet wrench W
Drive _R simultaneously and tighten each bolt 35. After a lapse of a predetermined time from the start of tightening the bolts 35, the air cylinders 39 are activated to rotate the ratchet wrench W _R all at once from the virtual line position to the solid line position in FIG. As a result, the ratchet gear 41 of each ratchet wrench W _R tightens each bolt 35 to the specified torque. As a result, the tightening work of the bolt 35 and the tightening torque management thereof can be efficiently performed.

[0034]

As described above, according to the present invention, the screw tightening work is performed by using a plurality of nut runners even though there is only one handling means for moving the nut runner according to the screw tightening work site. The screw tightening time required for screw tightening of one work is short, and the cycle time can be shortened especially in an automated assembly line.

Further, the reaction force in the rotational direction generated by the screw tightening work by each nut runner is received by the fixed fixture plate having high rigidity, so that the screw tightening torque can be increased, The tightening torque is not limited as compared to the case where the nut runner attached to the robot is used to tighten the screw.

Furthermore, when performing screw tightening work on a large number of screw tightening work sites around the entire circumference of a work to be screw tightened, in the case where a screw member is supplied to the nut runner via a screw supply hose each time. However, by using multiple nut runners, the connection between the nut runners and the hose for screw supply can be directed to the outside of the work, so interference between the work and the hose for screw supply can be reasonably avoided. As a result, unlike the conventional art, an actuator for changing the posture of the nut runner in order to avoid the interference between the work and the screw supply hose is not required.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the present invention.

FIG. 2 is an enlarged plan view of the fixture plate shown in FIG.

FIG. 3 is an enlarged cross-sectional view of an essential part showing the relationship between the nut runner and the fixture plate shown in FIG.

FIG. 4A is an explanatory view showing a relationship between a work after completion of a screw tightening work and a counterpart component, and FIG. 4B is a plan explanatory view of FIG. 4A.

FIG. 5 is a structural explanatory view of an automatic assembling device that controls bolting between the work and the counterpart component shown in FIG. 4;

FIG. 6 is an enlarged view of a main part of FIG.

FIG. 7 is a structural explanatory view showing an example of a conventional screw tightening device.

[Explanation of symbols]

6 ... Fixture plate 8A, 8B ... Nut runner 11 ... Locate pin (positioning fitting part) 13 ... Handling robot (handling means) 16 ... Hand 18a, 18b to 31a, 31b ... Locate hole (positioning reference part) B ... Bolt P _{1 to} P ₁₄ … Bolt tightening work area (screw tightening work area) W… Transaxle case (workpiece)

Claims (1)

[Claims] 1. An apparatus for performing a screw tightening operation on each of a large number of screw tightening work parts, wherein a fixture plate fixedly arranged above the work and a plurality of the screw tightening work parts on the fixture plate are provided. It has a positioning reference part formed individually and a positioning fitting part capable of fitting with the positioning reference part, and either of the positioning fitting parts is selected depending on the screw tightening work site where the screw tightening work is to be performed. It has a plurality of nut runners that are detachably attached to the fixture plate by being fitted to the positioning reference part, and a hand that holds the nut runners, depending on the screw tightening work site where the screw tightening work is to be performed. And a handling means for moving the nut runner among a large number of positioning reference parts. Clamping device.