JPS643612B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves moving the tip of a chuck unit in an automatic screw tightening machine to a mark or hole that is eccentric within a predetermined range from a predetermined working position, and then moving the X-θ table. This invention relates to an automatic screw tightening machine that aligns the tip of a chuck unit with the center of a positioning hole.

Conventionally, automatic screw tightening machines equipped with this type of alignment sensor use a combination of a camera, an image sensor, and a computer to detect a screw tightening point, which is a predetermined working position on a work surface, and then,
Using a precision positioning table such as an XY table, move the chuck unit to that position,
He was doing that adjustment. However, while this method is highly versatile, it has the disadvantage that the control circuit and drive circuit must be sophisticated in order to increase the alignment accuracy, resulting in a very expensive product. . Therefore, there is a need for a low-cost control device that is significantly simplified and does not require high accuracy for controlling the positioning table to reach the detection range of a predetermined work position.

The present invention aims to meet the above-mentioned demands, and embodiments will be described below based on the drawings.

In FIGS. 1, 2, and 4, reference numeral 1 denotes an automatic screw tightening machine, which is comprised of a self-aligning device 2, a check unit 3, and an alignment sensor 4. The self-aligning device 2 has an arm 5 and a movable table 6, and the arm 5 is integrally fixed onto the movable table 6 and is rotatably attached. The moving table 6 is configured to move in the X-axis direction by an X-axis motor 7 made of a pulse motor, and the arm 5 is configured to move in an arc in the θ-axis direction by a θ-axis motor 8 made of a pulse motor. There is. Bracket 24 of the movable table 6
An origin sensor 10a is provided for detecting the origin (X0) of the moving table 6 in the X-axis direction. Further, the housing 25 on the movable table 6 is provided with an origin sensor 10b for detecting the origin (θ 0) of the arm 5 in the θ-axis direction.

A screw tightening unit 26 is provided at the tip of the arm 5.
is retained. A chuck unit 3 is attached to the tip of the screw tightening unit 26, and inside the chuck unit 3 there is a structure configured such that it can be rotated freely by a drive source and can be raised and lowered by an air cylinder inserted in the screw tightening unit 26. A driver bit (not shown) is located.

A joint base 14 is attached to the chuck body 9 of the chuck unit 3, as shown in FIGS. 1 and 3. A sensor holder 13 is attached to the joint base 14 by a joint pin 15a, and the sensor holder 1
3 is rotatably held by a joint base 14. An alignment sensor 4 is attached to the sensor holder 13 at the tip of the check unit 3.

The sensor holder 13 is provided with a protrusion. The protrusion is rotatably held by a joint 18, which will be described later. On the other hand, a bracket 19 is integrally attached to the body of the chuck unit 3, and an air cylinder 16 is rotatably attached to the bracket 19. A joint 18 is attached to the tip of the rod 17 of the air cylinder 16 by a joint pin 15b,
The alignment sensor 4 is configured to be separated from the tip of the check unit 3 by the air cylinder 16.

The alignment sensor 4, as shown in FIGS. 3 and 5, is a projection type sensor and consists of a light projector 11 and a light receiver 12. The projector 11 is arranged so that the projection point P on the surface of the workpiece 20 is always located below the tip of a driver bit (not shown). On the other hand, the light receiver 12 is placed at a position relative to the reflected light from the projection point P, and is arranged in the X(+), X(-), θ(+), and θ(-) directions in the locus 21 of the projection point P. It is configured to convert the state of one side into an on/off signal and detect the positioning hole 22 on the surface of the workpiece 20.

The automatic screw tightening machine configured as described above has a control device (not shown), and the control device controls rotation by supplying a predetermined number of pulses to the X-axis motor 7 and the θ-axis motor 8. is configured to do so. The X-axis motor 7 and the θ-axis motor 8
As shown in Figures 5 and 6, the number of supplied pulses (XN, θN) is set as the initial condition to O pulse (XN
=O, θN=O), and X(+) and θ(+)
The amount of movement (NX, Nθ) on one side in the direction is set to one pulse (NX = 1, Nθ = 1).

Next, after the X-axis motor 7 and the θ-axis motor 8 operate under the initial conditions, the
The specified number of pulses (XN+αX, θN+
αθ) is supplied, and the movement amount (αX, αθ) of one side in the X(-) and θ(-) directions can be obtained. The amount of movement of one side in the X(-) and θ(-) directions is set to increase by αX and αθ (NX←NX+αX, Nθ←Nθ+αθ) from the movement amount under the initial condition. Thereafter, the amount of movement of one side in the X(+) and θ(+) directions is increased by αX and αθ from the amount of movement of one side in the X(-) and θ(-) directions.
←NX+αX, Nθ←Nθ+αθ), moving table 6 in the X direction and arm 5 in θ
The chuck unit 3 is configured to move approximately spirally while being moved alternately in the directions.
Further, the increasing movement amount of one side (αX, αθ) is set smaller than the diameter of the positioning hole 22.

Next, a mechanism for controlling the positioning of the positioning hole 22 to the center point O, which is a main part of the present invention, will be explained.

The alignment sensor 4 is again shown in FIGS. 7 and 8.
As shown in the figure, X in the locus 21 of the projection point P
The state of each side in the (+), It is configured.

Therefore, the positioning control mechanism first sets the number of pulses (XN) supplied to the X-axis motor 7 to O pulses (XN←O), and then rotates the movable table 6 for each pulse to move the movable table 6 from the predetermined working position 23. X(+)
It is configured to move in the direction up to point A1.

Next, after the initial operation of the X-axis motor 7,
The number of pulses (XN) is supplied to the X-axis motor 7,
Move the moving table 6 from the above point A1 in the X (-) direction.
It is configured to move to point A2 (XN+1). Furthermore, the number of pulses that is 1/2 of the number of pulses (XN) is supplied to the X-axis motor 7 again, and the moving table 6 is moved from point A2 to point B in the X (+) direction by 1/2 of the amount of movement. 2. Configured to move.

On the other hand, the θ-axis motor 8 changes the number of supplied pulses (θN) to 0 pulses (θN←O), as shown in FIG.
After that, the arm 5 is rotated every pulse and the arm 5 is
It is configured to move from the point to the C1 point in the θ (-) direction.

Next, after the θ-axis motor 8 initially operates,
The number of pulses (θN) is supplied to the θ-axis motor 8,
The arm 5 is configured to move from the C1 point to the C2 point (θN+1) in the θ(+) direction. Furthermore, the number of pulses (θN) is applied to the θ-axis motor 8 again.
1/2 of the number of pulses is supplied, and arm 5 is connected to the C2
1/2 of the above movement amount from the point to the O1 point in the θ (-) direction
Configured to move.

As shown in FIGS. 7 and 8, the movable table 6 and the arm 5 having the amount of movement configured in this way are moved in a substantially cross shape so as to move closer to point O, which is the center point of the positioning hole 22. Move on the trajectory 21 multiple times and convert the number of times (N) to a predetermined number of times (NO=
2), and is configured to stop after a predetermined number of times. Therefore, first, the X-axis motor 7 changes the number of supplied pulses (XN) to O pulses (XN←O), and then rotates every pulse to move the moving table 6 from the predetermined working position 23 in the X (+) direction. is configured to move to point D1.

Next, after the initial operation of the X-axis motor 7,
The number of pulses (XN) is supplied to the X-axis motor 7,
Move the moving table 6 from the D1 point in the X (-) direction.
It is configured to move to point D2 (XN+1). Furthermore, the X-axis motor 7 is again supplied with a pulse number that is 1/2 of the number of pulses (XN), and the moving table 6 is moved from the D2 point to the O2 point in the X (+) direction by 1/1 of the amount of movement. 2. Configured to move.

When performing alignment work using the automatic screw tightening machine 1 that combines the above-mentioned self-aligning device 2, chuck unit 3, and alignment sensor 4, as shown in Fig. 1, Fig. 2, Fig. 4, and Fig. 5. , the X-axis origin (X 0) of the moving table 6 and the θ-axis origin (θ
0) is confirmed by each origin sensor 10a, 10b, the X-axis motor 7 and the θ-axis motor 8 are driven, and the check unit 3 and the arm 5 are integrally moved to the
The driver bit (not shown) is moved in the axial direction and the θ-axis direction to position the driver bit (not shown) at a predetermined working position 23 on the surface of the workpiece 20.

Therefore, as shown in FIGS. 5 and 6, when the alignment sensor 4 is started and the positioning hole 22 cannot be confirmed at the predetermined working position 23,
Apply one pulse to the X-axis motor 7 to move the check unit 3 and alignment sensor 4 to a predetermined working position 23.
Move the surrounding area by a predetermined amount in the X (+) direction. Therefore,
There is a positioning hole 22 on the locus 21 of the projection point P that has moved a predetermined amount in the
When the positioning hole 22 is turned on), the alignment with the positioning hole 22 is completed.

However, if there is no positioning hole 22 on the trajectory 21 in the X (+) direction, after checking whether the number of pulses on the trajectory 21 is 1 pulse, θ
One pulse is applied to the shaft motor 8 to further move the check unit 3 and alignment sensor 4 by a predetermined amount in the θ (+) direction. Therefore, there is a positioning hole 22 on the locus 21 of the projection point P that has moved in the θ(+) direction, and when the positioning hole 22 is detected, alignment with the positioning hole 22 is completed.

However, if there is no positioning hole 22 on the trajectory 21 in the θ (+) direction, after checking whether the number of pulses on the trajectory 21 is 1 pulse, the is added, and the alignment sensor 4 is moved by a predetermined amount in the X (-) direction.
Therefore, the locus 21 of the projection point P in the X(-) direction
There is a positioning hole 22 on the top, and the positioning hole 22
When detected, alignment with the positioning hole 22 is completed.

However, if there is no positioning hole 22 on the trajectory 21 in the and a predetermined number of pulses are applied to move the alignment sensor 4 by a predetermined amount in the θ (-) direction. Therefore, there is a positioning hole 22 on the locus 21 of the projection point P that has moved in the θ (-) direction, and when the positioning hole 22 is detected, alignment with the positioning hole 22 is completed.

However, if there is no positioning hole 22 on the trajectory 21 in the θ (-) direction, after confirming that the number of pulses on the trajectory 21 is 1 pulse and the predetermined number of pulses, the A predetermined number of pulses are applied, and the alignment sensor 4 is again moved by a predetermined amount in the X (+) direction to continue alignment with the positioning hole 22.

In this way, since alignment is performed by moving the chuck unit 3 and the alignment sensor 4 in a substantially spiral manner and making the amount of movement smaller than the diameter of the positioning hole 22, the positioning hole 22 is always detected. . However, the detected positioning hole 22
The detected position does not coincide with the center point O of the positioning hole 22.

Therefore, as shown in FIGS. 7 and 8, one pulse is applied to the X-axis motor 7 again to move the check unit 3 and alignment sensor 4 into the positioning hole 2
X(+) from a predetermined working position 23 within the circumference of
direction, one pulse at a time. Therefore, the alignment sensor 4 is turned on inside the circumference of the positioning hole 22 and turned off outside the circumference, and
Detect point A1 on the intersection with the axis (phs: off),
Place the tip of the chuck unit 3 at a predetermined working position 23.
Position it from point A1.

Next, after check unit 3 reaches point A1,
A pulse number is applied to the X-axis motor 7 to move the alignment sensor 4 by a predetermined amount in the X (-) direction. Therefore,
The alignment sensor 4 detects point A2 on the intersection point (PHS: OFF) and aligns the tip of the check unit 3.
Position it from point A1 to point A2. Furthermore, after the chuck unit 3 reaches point A2 on the intersection point,
A predetermined number of pulses are applied to the X-axis motor 7, and the alignment sensor 4 is moved by 1/2 of the predetermined movement amount in the X (+) direction. Therefore, the alignment sensor 4 is placed on the straight line A1A2 between the intersection points A1 and A2, and the centering sensor 4
Detect the point and position the tip of the chuck unit 3 from point A2 to point B.

On the other hand, the chuck unit 3
After reaching point B, which is the midpoint of A1A2, one pulse is applied to the θ-axis motor 8, and the check unit 3 and alignment sensor 4 are moved in the θ (-) direction every pulse. Therefore, the alignment sensor 4 detects point C1 (phs: off) on the intersection of the circumference of the positioning hole 22 and the arc of the θ axis, and positions the tip of the check unit 3 from point B to point C1.

Next, after the chuck unit 3 reaches the point C1 on the intersection point, a number of pulses are applied to the θ-axis motor 8 to move the alignment sensor 4 by a predetermined amount in the θ(+) direction. Therefore, the alignment sensor 4 detects the C2 point on the intersection point (PHS: OFF), and positions the tip of the check unit 3 from the C1 point to the C2 point.
Furthermore, the chuck unit 3 is located on the intersection point.
After reaching point C2, a predetermined number of pulses are applied to the θ-axis motor 8, and the alignment sensor 4 is moved by 1/2 of the predetermined movement amount in the θ(-) direction. Therefore, the alignment sensor 4 is placed on the arc C1C2 of the intersection points C1 and C2,
Point O1, which is the intermediate point, is detected, and the tip of check unit 3 is positioned from point C2 to point O1.

By the way, the position of the tip of the chuck unit 3 is determined from the point O1 and further from the center point O of the positioning hole 22.
1 pulse is applied to the X-axis motor 7 to bring it closer to the
is moved from the O1 point in the X (+) direction every pulse. Therefore, the alignment sensor 4 is inserted into the positioning hole 22.
Detect point D1 on the intersection of the circumference and the X axis (phs:
off), and then connect the tip of chuck unit 3 to the O1
Position from point to point D1.

Next, after check unit 3 reaches point D1,
A pulse number is applied to the X-axis motor 7 to move the alignment sensor 4 by a predetermined amount in the X (-) direction. Therefore,
The alignment sensor 4 detects point D2 on the intersection point (PHS: OFF), and aligns the tip of the check unit 3.
Position from point D1 to point D2. Furthermore, after the chuck unit 3 reaches point D2 on the intersection point,
A predetermined number of pulses are applied to the X-axis motor 7, and the alignment sensor 4 is moved by 1/2 of the predetermined movement amount in the X (+) direction. Therefore, the alignment sensor 4 is placed on the straight line D1D2 between the intersection points D1 and D2 at the midpoint thereof.
Detect the O2 point and move the tip of the chuck unit 3 to D2.
from the point to the O2 point, and continue aligning while approaching the center point O of the positioning hole 22.

Since the moving amounts of the moving table 6 and the arm 5 are configured as described above, by repeating the required number of times along the substantially cross-shaped locus 21, the tip of the chuck unit can be moved to the center point O of the positioning hole 22. This allows for high precision alignment without adding any supplementary mechanism.

As explained above, the present invention provides an alignment sensor that is removably held at the tip of a chuck unit attached to a self-aligning device consisting of an X-θ table. Since it is configured to move in a substantially cross-like pattern and repeat this substantially cross-like movement until it detects the center point of the positioning hole, a highly accurate check unit and positioning hole can be created by simply giving certain instructions to the control device. Alignment with the center point is possible, and as a result, control is simplified and the control device is inexpensive.

[Brief explanation of the drawing]

Figure 1 is a side view of an automatic screw tightening machine according to the present invention, Figure 2 is a plan view of the main parts of Figure 1, and Figure 3 is a
An enlarged view of the chuck unit with an alignment sensor seen from the line A-A in the figure, Fig. 4 is a diagram showing the movement range of the chuck unit, Fig. 5 is a locus diagram of the projection point on the work surface, and Fig. 6 is a diagram showing the movement range of the chuck unit. 5 shows a flowchart, FIG. 7 shows a locus of the projection point within the circumference of the positioning hole, and FIG. 8 shows a flowchart of the present invention. 1... Automatic screw tightening machine, 2... Self-aligning device,
3...Chuck unit, 4...Alignment sensor,
5...Arm, 6...Movement table, 7...X-axis motor, 8...θ-axis motor, 9...Chuck body, 10a, 10b...Origin sensor, 11...
Emitter, 12... Light receiver, 13... Sensor holder, 14... Joint base, 15a, 15b
...Joint pin, 16...Air cylinder,
17...rod, 18...joint, 19...
Bracket, 20...Work, 21...Trajectory, 2
2...Positioning hole, 23...Predetermined working position, 2
4...Bracket, 25...Housing, 26...
...Screw tightening unit.

Claims (1)

[Claims] 1. A self-aligning device 2 consisting of a moving table 6 that moves in the X direction by a pulse motor and an arm 5 that moves in the θ direction, a chuck unit 3 attached to the tip of the arm 5, and the chuck unit. In an automatic screw tightening machine for aligning the tip of the chuck unit 3 with the positioning hole 22, the chuck unit 3 is provided with an alignment sensor 4 which is detachably held at the tip position of the chuck unit 3. Move to
After moving the tip of the chuck unit 3 onto the positioning hole 22, the alignment sensor 4 again detects two intersection points where the circumference of the positioning hole 22 intersects with the X-axis, and moves the table to an intermediate position between the two intersection points. 6, detect two intersection points where the circumference of the positioning hole 22 intersects with the arc of the θ axis, move the arm 5 to a position intermediate between the two intersection points, and continuously move the chuck unit 3 in a substantially cross shape. An automatic screw tightening machine characterized in that the automatic screw tightening machine is configured to repeat the movement a necessary number of times.