JPH085413B2 - How to assemble parts - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method of assembling two parts, such as an automobile engine and a transmission, for example.

2. Description of the Related Art As a method of assembling an engine and a transmission mounted on an automobile to each other, there is a method in which an operator changes the position of the transmission with respect to a positioned engine. There is one disclosed in Japanese Patent No. 73374.

In the former method, the worker finds the optimum mounting position by changing the posture of the transmission while repeating trial and error, and thus requires skill to perform the work.
The working time is extremely long.

On the other hand, in the latter method, since the rotating members of both the engine and the transmission are phase-matched by the contact-type phase-matching member, it is possible to save labor, but it takes a long time to complete the phase-matching.

In addition, the latter method is only concerned with rotational alignment, so it is premised that the axes of the engine and transmission are aligned with each other, and therefore the positioning of the engine and transmission prior to phase alignment is In addition to requiring high accuracy, a slight misalignment will cause trouble.

Means for Solving the Problems The present invention is intended to solve the above problems, and as shown in the embodiments, two parts supported by individual supporting means are made to face each other with their respective mounting surfaces facing each other. In the method, the two mounting means are assembled by bringing them closer to each other and joining the two mounting surfaces to each other, wherein the two supporting means are necessary to correct the relative position error between the two parts. As a total sum of the degrees of freedom of the two parts, there are three orthogonal degrees of freedom including the approaching direction of the two parts in one axis and rotational freedom in the rotation direction with the approaching direction as the center of rotation. A step of individually photographing the assembly reference positions which are provided in each assembly surface and are paired with each other by two cameras which are arranged inside and opposite to each other on the same axis; Assembling reference position that forms a pair from the image captured by the camera And a position correction command corresponding to the calculated relative position error is given to at least one of the supporting means as a position correction command for the component. A step of making the two assembly reference positions coincide with each other, withdrawing the two cameras from the facing gap of the two parts, and then bringing the two parts closer to each other to join the two assembly surfaces to each other Includes and.

The above-mentioned assembly reference position includes bolt holes, bolts and bolt holes, positioning pins and positioning holes, and the like.

Embodiment FIG. 6 to FIG. 8 are views showing an example of an assembling apparatus to which the method of the present invention is applied, and exemplify a case where the aforementioned engine and transmission are assembled.

As shown in FIGS. 6 to 8, in the engine E conveyed by the overhead conveyor 1, the lifter 2 as a supporting means moves upward to move the lifter 2
It is transferred onto the lifter table 3 of. A drive unit 32 having an air cylinder 35 for pressing the engine E toward the transmission M and a socket 33 for rotating the crankshaft of the engine E at a slow speed is mounted on the lifter table 3.

The lifter table 3 moves up and down by moving the lower end of one of the links 4 and 5 in the X-shape in the horizontal direction by the motor 6.

Similarly, the transmission M conveyed by the conveyor 7 is transferred onto the lifter table 9 of the lifter 8 as a supporting means by a transfer lifter (not shown).

The lifter table 9 has a link as shown in FIG.
The lower end of 10 is moved horizontally by a motor 11 to move up and down. When the lower end of the link 10 is moved in the X ₁ direction, for example, the lower end of the other link 31 is simultaneously moved in the X ₁ direction by the motor 12 to move the lifter table 9 itself in the horizontal direction. be able to. Further, the lifter table 9 can change its inclination in the θ direction by operating the motor 13 and the Y direction position by operating the motor 40.

That is, the lifter table 3 can move up and down in the Z direction, while the lifter table 9 can move in the Z direction, the X direction, and the θ direction, respectively.

A slide table 14 is provided on the lifter table 9, and the slide table 14 slides in the Y direction by the operation of the air cylinder 15.

Reference numeral 16 denotes an articulated industrial robot (hereinafter, simply referred to as a robot). A hand 19 of the robot 16 has two CCD cameras (hereinafter, simply referred to as camera) which are opposite to each other as shown in FIG. 9 and FIG. 17, 18) are arranged on the same axis. The robot 16 also functions as a robot for bolting work, as will be described later. Therefore, the hand 19 is provided with a pair of nut runners 20 and 21 in addition to the cameras 17 and 18. 22 is a light source for illumination.

Since the pitches of bolt holes, which will be described later, differ depending on the type of the engine E or the transmission M, the pitches of the nut runners 20 and 21 are variable due to the action of the motor 23.

FIG. 1 schematically shows the state of FIG. 6, and FIG.
As shown in the figure, first, when the engine E and the transmission M are positioned on the respective lifters 2 and 8, the type information of the engine E and the transmission M is given from the higher order production instruction computer. Transmission M is a motor
By 40, the vehicle advances toward the engine E by a predetermined amount and enters the imageable area of the camera, which will be described later. Next, the robot 16 positions the cameras 17 and 18 at the first image capturing point P ₁ in the facing gap between the engine E and the transmission M by the position command based on the vehicle type information. Then, the first mounting reference position on each mounting surface F of the engine E and the transmission M, for example, the bolt holes B ₁ and B ₁₁ paired with each other are set to the first mounting reference position.
As shown in Figs. 3 and 4, the images are captured at the same time, the image is analyzed by a processing device (not shown), and as shown in Fig. 5, the coordinates (X _m1 , Z of each bolt hole B ₁ , B ₁₁ ) _m1 ), (X _e1 , Z _e1 )
Is calculated and stored. More specifically, the circles of the outlines of the bolt holes B ₁ and B ₁₁ are extracted from the above camera image, the center position of the circles is calculated, and the coordinates of (X _m1 , Z _m1 ) and (X _e1 , Z _e1 ) are calculated. The value.

Here, in this embodiment, the coordinate origin is unified in advance in order to perform the robot operation and the visual correction, and therefore, two cameras located on the same axis line are set.
Assuming that the origin positions of 17, 18 match, the coordinates (X
_m1 , Z _m1 ) and (X _e1 , Z _e1 ) are coordinate values based on the above coordinate origin.

Next, the robot 16 positions the cameras 17 and 18 at the second image capturing point P ₂ and captures the images of the bolt holes B ₂ and B ₁₂ which are the second reference positions in the same manner as described above. As shown, the coordinates (X _m2 , Z _m2 ), (X _e2 , Z of each bolt hole B ₂ , B _12
e2 ) is calculated and stored.

After the above-described image capturing is completed, the robot 16 withdraws the cameras 17 and 18 from the facing gap between the engine E and the transmission M and waits at the bolt tightening position, while in the processing device, the coordinates (X _m1 , Z). _m1 ), (X _e1 , Z _e1 )
And bolt holes based on (X _m2 , Z _m2 ), (X _e2 , Z _e2 ).
Calculate B ₁ , B ₁₁ and B ₂ , B ₁₂ relative position error (deviation amount).

That is, as shown in FIG. 5, the line connecting the coordinates of the two bolt holes B ₁₁ and B ₁₂ on the engine E side is defined as e, and the line connecting the coordinates of the two bolt holes B ₁ and B ₂ on the transmission M side. Is m, it is necessary to superimpose line m on line e.
The correction amounts ΔX, ΔZ, Δθ in the X, Z and θ directions are calculated.

Further, on the side of the robot 16, reference bolt hole positions B ₂₁ and B ₂₂ are pre-teached in order to perform bolting work on the above bolt holes B ₁ , B ₁₁ and B ₂ , B ₁₂ . Therefore, in addition to the above correction amount, the correction amounts ΔX ₁ , ΔZ ₁ , Δθ ₁ required to match the coordinates of the bolt holes B ₁₁ , B ₂₂ on the engine E side with the reference bolt hole positions B ₂₁ , B _22. To calculate.

Next, the correction amounts ΔX, ΔZ, and Δθ are given to the control system of the lifter 8 as correction commands. This correction command is given as deviation data of position data given in advance, the position of the transmission M in the X direction is corrected by the action of the motors 11 and 12, and similarly, the position in the Z direction is changed by the action of the motor 11. The position in the θ direction is corrected by the action of 13 so that the positions of the bolt holes B ₁ , B ₁₁ and B ₂ , B ₁₂ on the engine E side and the transmission M side coincide with each other.

Then, the socket 3 is pressed against the engine E by the air cylinder 35 of the drive unit 32, and when the transmission M is a manual type, the output shaft of the engine E is spline-connected, so that the socket 33 is driven at a slow speed by a motor (not shown). Rotate. Next, when the transmission M is moved forward in the Y direction toward the engine E by the action of the motor 40, both the mounting surfaces F, F approach each other, and the air cylinder 15 pushes them strongly to establish a joined state.

In this state, the robot 16 is restarted, and the bolts previously inserted in the nut runners 20 and 21 of the hand 19 are tightened into the bolt holes B ₁ (B ₁₁ ), B ₂ (B ₁₂ ) and the engine E and The transmission M is integrally connected. At this time, when the bolt is tightened as described above, the robot 16 uses the correction amount Δ
The position is corrected by X ₁ , ΔZ ₁ , and Δθ ₁ .

Here, in the above system, the camera 1
When the positional displacement of the cameras 17 and 18 occurs due to improper mounting of the cameras 7 and 18, it is recognized as positional displacement on the side of the object to be detected, and normal work cannot be performed. Therefore, the above-mentioned first
Another check point is set before the image capture point, and at this check point, for example, a fixed object with a predetermined mark is image-processed. Then, while the coordinates of the mark at the time of the first image processing are stored, the image processing for the above mark is executed for each cycle of the robot, and each time, the coordinates are compared with the previously stored coordinates. audit.

Then, if the coordinates at the image capturing point of the detected object are corrected according to the amount of deviation, the camera
It is possible to avoid the influence of the displacement of 17,18.

EFFECTS OF THE INVENTION According to the present invention, the assembling reference positions provided on the assembling surfaces of the two parts and forming a pair with each other are recognized by the two cameras located on the same axis and the positions are corrected. Because
Compared with the conventional method, the cycle time can be greatly reduced and highly accurate assembly work can be performed.

Further, if the above-mentioned correction amount is also fed back to the bolt tightening device, it is possible to realize completely unmanned assembly work including bolt tightening.

[Brief description of drawings]

1 is an explanatory view schematically showing FIG. 6 showing an embodiment of the present invention, FIG. 2 is a flow chart of the operation system in FIG. 1, and FIG. 3 is a direction of FIG. FIG. 4 is a view in the direction of arrow b in FIG. 1, FIG. 5 is an explanatory view of an image processing system, FIG. 6 is a plan view of an assembly apparatus to which the present invention is applied, and FIG. FIG. 6 is a front explanatory view of FIG. 6, FIG. 8 is a view in the direction of arrow A of FIG. 7, FIG. 9 is a plan view of the robot hand, and FIG. 10 is a front view of FIG. 2,8 ... lifter as support means, 16 ... industrial robots, 17, 18 ... CCD camera, E ... Engine, M ... _{Transmission, B 1, B 2, B} 11, B 12 ... bolt as the assembly reference position Hole.

Claims (1)

[Claims] 1. A method of assembling two parts, which are supported by individual supporting means, by assembling surfaces of each of them facing each other and then approaching each other to join the two assembly surfaces together. The two support means are orthogonal three-axis degrees of freedom including the approaching direction of the two parts in one axis as a total of the degrees of freedom of the entire support means necessary to correct the relative position error between the two parts, and the approaching degrees thereof. Each camera has a degree of freedom of rotation in the direction of rotation with respect to the direction of rotation, and is mounted by two cameras in opposite gaps of two parts and arranged in opposite directions on the same axis. And the step of individually imaging the assembly reference positions that form a pair, and detecting the assembly reference positions that form a pair from the images captured by the two cameras, and comparing the assembly reference positions with each other. Of calculating the relative position error of the A position correction command corresponding to the placement error is given to at least one of the supporting means as a position correction command of the parts so that the assembly reference positions of both parts coincide with each other, and the two cameras are retracted from the facing gap between the two parts. After that, 2
And a step of assembling the parts by bringing them closer to each other and joining the two assembly surfaces to each other.