JP2005196363A - Positioning device and component mounting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positioning device capable of moving a mobile element to a desired position at high speed regardless of the distance traveled by the mobile element, relating to a positioning technique for positioning the mobile element in an industrial machine tool. <P>SOLUTION: The positioning device is provided having a position command means for issuing a command to move the mobile element 20 to a desired position, and first position control means 17, 18, 19 for moving the mobile element from its current position to the desired position according to the position command means and stopping it at the desired position. The positioning device further includes second position control means 15, 12, 23 that, while comparing the position of the mobile element with the desired position as the mobile element moves according to the first position control means, help control the movement of the mobile element so that the mobile element reaches and stops at the desired position earlier than if the mobile element is moved to the desired position by the first position control means alone. A component mounting device is also provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a positioning technique for positioning a moving body in an industrial machine tool, and more particularly to a technique for positioning the moving body at high speed.

Conventionally, there is a positioning device as a device for moving a moving body to a predetermined position.
This positioning device uses a servo motor as a drive source and performs positioning of the moving body by linearly moving the moving body with a ball screw joined through a coupling (Japanese Patent Laid-Open No. 3-203294). Or a mode in which a linear motor and a linear scale are combined, the position of the moving body is read with the linear scale, and the moving body is positioned by driving the linear motor based on the read value. Known to. Such a positioning device can move the moving body at low cost and with high accuracy.
JP-A-3-203294

However, in general, for servo motors, the rise time until the rotation output reaches the maximum value after the voltage is applied, and the fall time until the rotation output becomes 0 after the applied voltage is cut off are very long. Long.
And if it is a positioning device mainly for long-distance movement that can maintain the rotation output at the maximum value for a long time, the delay of movement of the moving body due to its rise time and fall time is not a problem. When the main body is moved by a short distance (for example, 1 mm), or when the long distance movement and the short distance movement are mixed frequently, the delay of the movement of the moving body in the short distance movement becomes remarkable. Appears and becomes a problem.

  In particular, in a positioning device applied to an industrial machine tool, it becomes a serious factor that lowers the production efficiency. For example, in the case of a component mounting apparatus that mounts electronic components on a printed circuit board, due to the recent increase in the degree of integration of electronic components on the printed circuit board, a moving body (one for mounting each electronic component on the printed circuit board) In this case, the movement distance between the mounting positions to which the working head is moved is shortened. For this reason, the response speed of the servo motor has directly influenced the efficiency of mounting electronic components on a printed circuit board.

  Therefore, an object of the present invention is to provide a positioning device and a component mounting device that can move a moving body to a desired position at a high speed regardless of the moving distance of the moving body.

In order to solve the above problems, the present invention is configured as follows.
One aspect of the positioning device of the present invention is a position command means for issuing a command to move the moving body to a target position, and the moving body is moved from the current position of the moving body to the target position based on the position command means. And the first position control means for stopping the moving body at the target position, and comparing the position of the moving body moving based on the first position control means and the target position. However, the moving body can reach the target position earlier than the case where the moving body is moved to the target position by only the first position control means, and the moving body can be stopped at the target position. And a second position control means for assisting in controlling the movement of the moving body.

  The second position control means moves the moving body by a moving distance of the moving body based on a command of the position command means or a predetermined distance within the moving distance along with the start of movement of the moving body. After the body reaches the target position, the moving position of the moving body by the second position control means or the movement of the predetermined distance on the moving system of the first position control means is not set to the target position. The moving body that is determined to have reached and continues to move by the first position control means may be configured to perform auxiliary control so as to move in a direction opposite to the traveling direction of the moving body.

Further, the second position control means advances or retracts a part or the whole of the moving system by the first position control means in the moving direction of the moving body by expansion or contraction of at least one piezoelectric element. You may comprise as follows.
In each of the above aspects, the first position control means may be a combination of a motor that is slow in response speed but capable of high-speed rotation and a ball screw that changes the rotational power of the motor into the linear movement force of the moving body. The position of the moving body may be controlled based on the rotation angle of the motor, and the second position control means may control the position of the moving body based on the absolute position of the moving body. .

  One aspect of the component mounting apparatus of the present invention is a process for mounting a plurality of electronic components on a printed circuit board by adsorbing and holding the electronic components on the work head based on horizontal movement and elevation movement of the work head. The position command means for issuing a command to move the work head to the target position, and based on the position command means, the work head is moved horizontally from the current position of the work head to the target position. The first position control means for stopping the work head at the target position and the position of the work head horizontally moving based on the first position control means and the target position are compared with each other. The work head is caused to reach the target position earlier than when the work head is horizontally moved to the target position by only the position control means, and the work head is moved to the target position. In assisting controls the horizontal movement of the work head to be stopped, and configured to have a second position control means.

  The second position control means moves the work head by a movement distance of the work head based on a command of the position command means or a predetermined distance within the movement distance at the same time as the movement of the work head starts. After the head reaches the target position, the moving position of the working head by the second position control means or the movement of the predetermined distance is not set to the target position by the moving system of the first position control means. The working head that is determined to have reached and continues to move by the first position control means may be configured to be auxiliary-controlled so as to move in the direction opposite to the traveling direction of the working head.

  Further, the first position control means has a rotation angle of the servo motor configured in the servo motor in a combination of the servo motor and a ball screw that changes the rotational power of the servo motor into the linear movement force of the work head. And the second position control means detects the absolute position of the work head with a linear scale, and a part or the whole of the moving system by the first position control means is controlled by the second position control means. The at least one piezoelectric element may be advanced or retracted in the moving direction of the working head by expansion or contraction.

In the present invention, when the movement control of the moving body to the target position by the first position control means is performed, the second position control means is connected to the moving body so as to advance the arrival time of the moving body to the target position. It is possible to act on the movement to the target position.
Particularly, since the second position control means acts on the movement of the moving body to the target position when the moving body starts moving, the moving body can reach the target position quickly. Then, the moving body that is moved to the first position control means immediately after the moving body reaches the target position as a result of the moving body having reached the target position quickly, is the second position control means. Can be stopped at the target position by moving in the direction opposite to the moving direction of the moving body.

In the present invention, by applying the above aspect to a component mounting apparatus, the work head can be moved horizontally at a high speed with respect to a predetermined position such as an electronic component suction position or an electronic component mounting position.
Then, the work head is moved by the first position control means after the work head has moved at a high speed to the predetermined position, and the work head is moved by the second position control means in a direction opposite to the movement. The time required for the operation can be, for example, within the time of the lifting and lowering operation of the work head.

  As described above, according to the positioning device of the present invention, the range in which the response speed is slow with respect to the movement of the moving body by the first position control means is compensated by the second position control means having a high response speed. A wide range of movement and a short positioning time (especially shortening the time required for deceleration and stopping at the end of positioning operation) can be achieved, and the moving body can be moved to a desired position at high speed regardless of the moving distance of the moving body. It becomes possible.

  Further, according to the component mounting apparatus of the present invention, the work head can be moved to a desired position at a high speed, so that the production efficiency is greatly increased.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings.
FIG. 1 is an example of a positioning device which is the best mode for carrying out the present invention.
This positioning device is a positioning device in a form in which a moving body is moved by the rotation of a ball screw, and this figure shows a side view of the positioning device.

  The positioning device 10 in FIG. 1 includes a first frame 11, a linear scale 12, a guide rail 13, a second frame 14, a laminated piezoelectric element 15, a ball screw holding member 16, a ball screw 17, a servo motor 18, a coupling 19, a nut 21, and The moving table 20 includes a bearing 22 and a detector 23.

The first frame 11 extends horizontally, a linear scale 12 is formed on a side surface thereof, and a guide rail 13 is formed on the lower side thereof along the first frame 11. A second frame 14 extending downward is joined below the left end of the first frame 11.
The second frame 14 has a through hole at the center thereof, and a laminated piezoelectric element 15 and a ball screw holding member 16 having a through hole having the same central axis as the central axis of the through hole are configured in this order on the right side. Yes.

  The ball screw 17 is held by the ball screw holding member 16 from the left end, and is connected to the servo motor 18 through the ball screw holding member 16, the laminated piezoelectric element 15, and a through hole formed in the second frame 14. However, the servo motor 18 and the ball screw 17 are joined via a coupling 19.

On the other hand, the right end of the ball screw 17 is slidably held in the direction of the rotation axis of the ball screw 17 (left and right direction in the figure) by other ball screw holding members (not shown in the figure). It is configured to be parallel to the first frame 11.
The moving table 20 has a through hole formed from the left end to the right end in the figure, and a nut 21 is further formed at the left end.

Then, the moving table 20 is moved so that the through-hole is slidable with respect to the rotation of the ball screw 17 and is further moved linearly on the ball screw 17 by the nut 21 along with the rotation of the ball screw 17. Are fitted.
Further, a bearing 22 is formed on the upper surface of the moving table 20, and the bearing 22 extends along the guide rail 13 so that the moving table 20 can move along the guide rail 13 fixed to the first frame 11. And are slidably engaged.

Further, the moving table 20 is a detector from the moving table 20 toward the linear scale 12 so that the current position of the moving table 20 indicated by the linear scale 12 fixed to the first frame 11 can be accurately detected. 23 is projected.
As described above, the positioning device 10 of the present example is configured such that the ball screw 17, the guide rail 13, and the linear scale 12 are parallel, and the detector 23 protrudes from the moving table 20 in a direction orthogonal to them.

  In the positioning device 10 having the above-described configuration, the servo motor 18 is rotated based on a position control signal from a control unit (not shown), and the rotational power is transmitted to the ball screw 17 through the coupling 19. The thickness of the laminated piezoelectric element 15 is changed based on voltage control from the control unit. In the laminated piezoelectric element 15, by applying a predetermined voltage value and expanding it by a predetermined amount as a reference thickness, the reference thickness can be reduced by controlling the voltage. Can do. The reason why the laminated piezoelectric element 15 is expanded by a predetermined amount in this manner will be described in detail later, but the influence of the overshoot of the moving table 20 based on the servo motor 18 is absorbed by the expansion / contraction action of the laminated piezoelectric element. Because.

  Thus, the rotational power transmitted from the servo motor 18 to the ball screw 17 acts as a force that linearly moves the moving table 20 in the horizontal direction (left-right direction in the figure) via the nut 21 formed at the left end of the moving table 20. At the same time, the change in the thickness of the laminated piezoelectric element 15 acts to move the ball screw 17 in the direction of the rotation axis of the ball screw 17 (the left-right direction in the figure).

As a result, the absolute position of the moving table 20 can be moved by moving the ball screw 17 in the direction of the rotation axis and moving the moving table 20 on the ball screw 17.
FIG. 2 is a control block diagram for controlling the position of the moving table 20 in the positioning device 10.

FIG. 2A is a control block diagram for controlling the position of the moving table 20 with respect to the ball screw 17 by driving the servo motor 18.
A control block diagram 30 shown in FIG. 3A includes a position command unit 31, a control unit 32, and an optical encoder 33.

  The position command unit 31 provides the control unit 32 with information on the position at which the movement table 20 is moved (also referred to as destination position information or target position information in this specification). This destination position information is given to the control unit 32 at a predetermined timing, for example, when a program for controlling the movement of the movement table 20 read into the storage unit is executed by the CPU.

  The control unit 32 receives the destination position information given from the position command unit 31, the current position information of the movement table 20 stored in advance, and the initial position information (rotation) of the movement table 20 fed back from the optical encoder 34 described later. The movement amount information (power information and the like) for moving the movement table 20 to the movement destination is output to the servo motor 33 based on the angle.

The servo motor 33 changes the movement amount information output from the control unit 32 into rotational power. Then, the rotational power of the servo motor 33 is transmitted to the ball screw 17 to move the moving table 20.
The optical encoder 34 detects the rotation angle of the servo motor 33 at a predetermined timing, and the control unit 32 detects the value of the detected rotation angle (this value follows the amount of movement of the moving table 20 on the ball screw 17). To give feedback.

As described above, in the control system (first position control means) shown in FIG. 5A, the position of the moving table 20 as viewed from the ball screw 17 is detected in real time from the rotation angle of the servomotor 18, and the servomotor. The amount of rotation of 18 is sequentially controlled.
On the other hand, FIG. 4B is a control block diagram for controlling the absolute position of the moving table 20 (the position of the moving table 20 as viewed from the first frame) by changing the thickness of the laminated piezoelectric element 15.

A control block diagram 40 shown in FIG. 4B includes a position command unit 41, a control unit 42, an actuator 43 and a detection unit 44.
The position command unit 41 gives the control unit 42 information on the position where the movement table 20 is moved (also referred to as destination position information or target position information in this specification). The destination position information is given to the control unit 42 at a predetermined timing, for example, when a program for controlling the movement of the movement table 20 read into the storage unit is executed by the CPU.

  The control unit 42 receives the movement destination position information given from the position command unit 41 and the initial position information (absolute position) of the movement table 20 stored in advance and the current position of the movement table 20 fed back from the detection unit 44 described later. The voltage applied to the actuator 43 is controlled based on the position information (absolute position).

  The actuator 43 is the laminated piezoelectric element 15 shown in FIG. 1 in this example, and when a voltage is applied, the actuator 43 expands in the right direction in FIG. 1 contracts to the left and returns to its original thickness when the voltage is turned off. In this example, since a voltage of a predetermined value determined in advance is applied to the laminated piezoelectric element 15 and the laminated piezoelectric element 15 is expanded by a predetermined amount as a reference thickness, the applied voltage is returned to the predetermined value. Thus, the multilayer piezoelectric element can be returned to the original reference thickness, and the multilayer piezoelectric element can be made thinner than the original reference thickness by lowering the voltage.

  In this example, the detection unit 44 includes the linear scale 12 and the detector 23 shown in FIG. 1, and detects the position of the moving table 20 that changes according to the expansion or contraction of the actuator 43 shown on the linear scale 12. Detect by. Then, the detected position information of the moving table 20 is fed back to the control unit 42.

Thus, in the control system (second position control means) shown in FIG. 5B, the absolute position of the moving table 20 indicated by the linear scale is detected in real time by the detector 23, and the voltage applied to the actuator is determined. Sequential control.
The two control systems shown in FIGS. 2A and 2B described above can operate independently without depending on each other.

Further, the position command units 31 and 41 can be made common. Further, the two control systems can be configured to depend on each other.
In the following description, only the position command unit 31 and the position command unit 41 are common, and the two control systems operate independently without depending on each other.

FIG. 3 is a graph showing the relationship between the position of the moving table 20 and the time at that position when the moving table 20 is moved in each control system.
FIG. 3A is a graph showing a case where the moving table 20 that moves based on the rotational power of the servo motor 18 decelerates near the target position and stops accurately at the target position.

FIG. 3B is a graph showing a case where the moving table 20 that moves based on the rotational power of the servomotor 18 overshoots at the target position.
The vertical axis in both figures is the distance (X) in the moving direction, and the horizontal axis in both figures is the moving time (t).
On the X axis in both figures, the movement destination (target position: Xp) of the moving table 20 and the maximum displacement (ΔX) that can be displaced in the X axis direction from the reference thickness when the laminated piezoelectric element 15 expands are shown. Has been.

Both figures now show three types of graphs.
Graphs L1 and L2 indicated by broken lines are graphs showing the relationship between the movement position of the movement table 20 that moves in the X-axis direction from the predetermined reference position on the servomotor 18 by the rotational power of the servomotor 18 and the movement time. . In this example, on the rotation axis of the ball screw 17 in FIG. 1, the position shown at the left end of the ball screw 17 viewed from the ball screw 17 (the position of the ball screw holding member 16 in the same figure) is X = 0, and the ball screw A predetermined position in the right direction of the figure as viewed from 17 is set as a target position, X = Xp.

  Graphs M 1 and M 2 indicated by alternate long and short dash lines are graphs showing the relationship between the movement position and the movement time of the ball screw 17 that moves in the X-axis direction due to expansion / contraction of the laminated piezoelectric element 15. That is, it is a graph showing a time change based on the expansion of the laminated piezoelectric element 15 at the position (reference point X = 0 in the graphs L1 and L2) shown at the left end of the ball screw 17 in FIG.

Graphs N1 and N2 indicated by solid lines are graphs showing temporal changes in the absolute position of the moving table when the graph L1 and graph M1, and the graph L2 and graph M2 interact with each other at each time, respectively.
In the graphs N1 and N2, a voltage of a predetermined value is applied to the laminated piezoelectric element 15, and the position of the left end of the ball screw in the state where the laminated piezoelectric element 15 has a reference thickness is defined as a reference position X = 0. Yes.

First, the graph of FIG. 3A will be described.
Referring to the graph L1 in FIG. 6A, the moving table 20 that moves on the ball screw 17 based on the rotation of the servo motor 18 slowly takes time from the movement start time (t = 0) to a predetermined time. Accelerating. Then, the moving table 20 whose speed has increased in this way starts to decelerate when approaching the target position Xp, approaches slowly to the target position Xp, and stops at the target position Xp.

Therefore, in this example, the voltage applied to the laminated piezoelectric element 15 is increased or decreased in the vicinity of the start of movement and the end of movement when the movement table 20 is moved at a low speed by the rotation of the servo motor 18.
As shown in the graph M1 in FIG. 5A, the laminated piezoelectric element 15 rapidly expands from time t = 0 to t = t2, and the expansion amount reaches the maximum (thickness ΔX) at time t = t2. Within this period, a high voltage is suddenly applied to the laminated piezoelectric element 15, and a large amount of charge is injected into the laminated piezoelectric element. Therefore, the laminated piezoelectric element 15 can expand at a speed much faster than the moving speed of the moving table 20 by the servomotor 18 and can move the moving table 20 together with the ball screw 17 in the moving direction of the moving table 20. This phenomenon is shown in the graph N1 in FIG. 5A, and it can be seen that the position of the moving table 20 viewed from the absolute position is moved by ΔX in the moving direction of the moving table 20 at time t = t2.

  In the control system using the servo motor 18, since it is not detected that the ball screw 17 and the moving table 20 are displaced in the moving direction of the moving table 20 from the time t = 0 including this time point to the time t = t 1, the servo motor 18 is not detected. The moving table 20 is controlled to move to a predetermined moving position (position on the ball screw 17) while looking at the rotation angle.

Until the time t = t3, as shown in the graph M1, the laminated piezoelectric element 15 is continuously applied with the same voltage and kept in its thickness state.
Subsequently, when time t = t3 is reached, it can be seen that the position of the movement table 20 as viewed from the absolute position has already reached the target position X = Xp as shown in the graph N1.

  At this time, in the control system that moves the moving table 20 by the rotational drive of the servo motor 18, the control is performed based on the position of the moving table 20 viewed from the ball screw 17, so the position of the moving table 20 is the target at the absolute position. It cannot be detected that the position Xp has been reached. Therefore, even after the position of the moving table 20 reaches the target position Xp in the absolute position, the control system continues to control the moving table 20 to move toward the target position Xp on the ball screw 17 (a ) As shown in the graph L1 after time t = t3.

  On the other hand, after the time t = t3, the control system for changing the thickness of the laminated piezoelectric element 15 apparently stops the movement of the moving table 20 that moves on the ball screw 17 by the rotation operation of the servo motor 18 from the absolute position. Then, the voltage applied to the laminated piezoelectric element 15 is controlled so as to draw a vertically symmetrical curve in the curve shown after time t = t3 in the graph L1, and the laminated piezoelectric element 15 that has expanded to the maximum is contracted. At time t = t1 when the rotational drive of the servo motor 18 stops, the voltage applied to the laminated piezoelectric element 15 is returned to the original voltage value, and the laminated piezoelectric element 15 is returned to the reference thickness.

  As described above, by controlling the rotation of the servo motor 18 and the expansion / contraction of the multilayer piezoelectric element 15 as described above after the time t = t3 when the movement of the moving table 20 stops apparently from the absolute position, the same is achieved. As shown in the graph N1 in FIG. 5A, the moving table can continue to stop at the target position Xp reached at time t = t3.

  Therefore, the stacking speed of expansion / contraction is higher than when the moving table 20 is moved to the target position Xp only by the control system that moves the moving table 20 by the rotation operation of the servo motor 18 (arrival time t = t1). The combination of the control system using the piezoelectric element 15 makes it possible to move the moving table to the target position Xp much earlier (arrival time t = t3).

Next, the graph of FIG. 3B will be described.
However, until the time t = t3 in FIG. 3B, each graph draws the same curve as in FIG. 3A, and the description thereof is a repetition of the description of FIG. In the following, description after time t = t3 will be given.

  The graph L2 has reached the target position Xp at time t = t4, but after that overshoot occurs and finally stops at the target position Xp at time t = t1. ing. That is, after time t = t4 when the movement table 20 reaches the target position Xp, the movement table 20 exceeds the target position Xp and feeds back the rotation angle of the servo motor detected by the optical encoder to return to the target position Xp. Although the servo motor is controlled, as shown in the graph L2 after time t = t5, the position of the moving table 20 returns too much, and the servo motor rotation angle detected by the optical encoder is fed back to the target position Xp again. By controlling the servo motor in the returning direction, the moving table 20 is stopped at the target position Xp at time t = t1. At this time, as shown in the figure, the moving table 20 reaches the position Xp + Xq at the maximum exceeding the target position Xp.

  On the other hand, after the time t = t3, the control system for changing the thickness of the laminated piezoelectric element 15 apparently stops the movement of the moving table 20 that moves on the ball screw 17 by the rotation operation of the servo motor 18 from the absolute position. Further, the voltage applied to the laminated piezoelectric element 15 is controlled so as to draw a vertically symmetrical curve on the curve shown after time t = t3 of the graph L2, and the laminated piezoelectric element 15 that has expanded to the maximum is contracted. The contracted laminated piezoelectric element 15 is expanded again.

  Referring to the graph M2 in FIG. 5B, a curve that is vertically symmetric with respect to the curve shown after time t = t3 of the graph L2 is shown with the position shown in the graph M2 at time t = t3 as a base point. You can see how they are. And from time t = t4 to t5, the position X shows a negative value.

As described above, since the laminated piezoelectric element 15 has a reference thickness when a predetermined voltage is applied at X = 0 in FIG. 5B, the laminated piezoelectric element 15 is laminated by further lowering the predetermined applied voltage. The thickness of the piezoelectric element 15 can be further reduced from the reference thickness.
Therefore, the negative X value shown from time t = t4 to t5 in FIG. 4B is achieved by further lowering the predetermined applied voltage. In this example, the thickness of the laminated piezoelectric element 15 is less than the reference thickness. Thinned to -Xq.

  As described above, by controlling the rotation of the servo motor 18 and the expansion / contraction of the multilayer piezoelectric element 15 as described above after the time t = t3 when the movement of the moving table 20 stops apparently from the absolute position, the same is achieved. As shown in the graph N2 in FIG. 5B, the overshoot by the servo motor 18 is absorbed, and the moving table 20 can continue to stop at the target position Xp reached at time t = t3.

  Therefore, the stacking speed of expansion / contraction is higher than when the moving table 20 is moved to the target position Xp only by the control system that moves the moving table 20 by the rotation operation of the servo motor 18 (arrival time t = t1). The combination of the control system using the piezoelectric element 15 makes it possible to move the moving table to the target position Xp much earlier (arrival time t = t3).

  As described above, by applying a voltage of a predetermined value to the laminated piezoelectric element 15 and setting the thickness of the laminated piezoelectric element at that time as a reference thickness, the two types of patterns (slow approach to the target position Xp) are obtained. However, if only low-speed approach to the target position Xp becomes a problem, for example, the pattern shown in FIG. A layer having a minimum thickness that does not apply a voltage to the laminated piezoelectric element 15 at X = 0 may be applied.

Next, an example of an industrial machine tool provided with a positioning device that controls the position of the moving table by the rotation of the servo motor and the expansion / contraction of the laminated piezoelectric element will be described.
Various types of industrial machine tools exist, and a component mounting apparatus used for automatically mounting electronic components on a printed circuit board will be described below with reference to the drawings.

FIG. 4 shows a perspective view of the component mounting apparatus.
FIG. 4A is a perspective view of the component mounting apparatus in which the internal mechanism is shown by a solid line, and FIG. 2B shows the internal mechanism of FIG. .
A fixed and movable pair of parallel board guide rails 404 are transported on the base 402 configured at the lower part of the component mounting apparatus 400 in FIG. It extends horizontally in the direction (X-axis direction, diagonally lower left to diagonally upper right). A loop-shaped conveyance belt (conveyor belt) that is not visible in the drawing is disposed so as to be in contact with the lower portion of the substrate guide rail 404.

  The conveyor belt is driven by a belt drive motor (not shown) with the side of the belt of several millimeters in width looking into the substrate conveyance path from below the substrate guide rail 404, and travels in the conveyance direction. While supporting both sides from below, the printed circuit board 406 before the electronic components are mounted is carried into the apparatus main body 400 from the upstream side of the line, and the printed circuit boards 406 having been mounted with the electronic components are sequentially carried out to the downstream side of the line. To do.

  Two printed circuit boards 406 are always carried into the component mounting device 400 and positioned by a printed circuit board positioning mechanism configured in the base 402, and the printed circuit board is fixed between the two circuit board guide rails 404. The printed circuit board is fixed at the position until the mounting of the electronic component is finished by the board fixing mechanism configured in the base 402.

  Although not shown in the figure inside the base 402, a positioning mechanism for determining the position of the printed board 406, a board fixing mechanism for fixing the printed board 406 between a pair of board guide rails 404, for example, A control device for controlling each part such as a ball screw and a laminated piezoelectric element to be described later, arithmetic processing, and the like are provided.

  A component supply table 408 is formed in front of and behind the base 402, respectively (the rear component supply table 408 in the diagonally upper left direction in the figure is hidden behind and cannot be seen. In FIG. (B), the rear part supply base 408 is not shown). A large number of tape cassette type component supply devices 410 (generally simply referred to as a tape feeder, a cassette type, or a tape component supply device) are arranged on the component supply base 408 as many as 50 to 70 pieces. The electronic components are sent out from the tape cassette type component supply device 410 to the component supply position.

  Above the base 402, a pair of left and right fixed rails (Y-axis rails) 412 extending in parallel to a direction (front-rear direction) perpendicular to the substrate transport direction is disposed. Moving rails (X-axis rails) 414 are slidably engaged along the Y-axis rails 412 before and after these Y-axis rails 412, and work head support towers 416 are aligned with the X-axis rails 114 along the X-axis rails 414. It is suspended slidably. That is, a total of four work head support towers 416 are disposed in the component mounting apparatus 400 shown here.

  The X-axis rail 414 shown here is engaged with a ball screw 417 inside the Y-axis rail 412 shown at a position where a part of the Y-axis rail 412 shown in FIG. Yes. A laminated piezoelectric element (not shown) is formed at the end of the ball screw 417 on the servo motor side (not shown). Further, a linear scale (not shown) is fixed to the frame of the Y-axis rail 412 so as to be parallel to the ball screw 412, and the position of the X-axis rail 412 indicated by the linear scale can be detected. From 414, a detector (not shown) is movably mounted on the linear scale.

That is, the X-axis rail 414 corresponds to the moving table 20 of FIG. 1, the ball screw 417 corresponds to the ball screw 17 of FIG. 1, and the positioning mechanism of the X-axis rail 414 is shown as an example in FIG. It is constituted by a positioning mechanism.
The control of the X-axis rail in this positioning mechanism takes the control described in detail with reference to FIG. 2, and the X-axis rail 414 is controlled by the rotation of the servo motor under the control of the control device housed in the base 402. In conjunction with the rotational drive of the ball screw 417, the ball screw 417 moves along the Y-axis rail 412 via the nut, and the ball screw 417 moves along the Y-axis rail 412 by the expansion / contraction of the laminated piezoelectric element. Move by the amount moved.

  Similar to the positioning mechanism for the X-axis rail 414, the positioning mechanism for the ball screw and the laminated piezoelectric element and the control method are also used for positioning the work head support tower 416 with respect to the X-axis rail 414. Therefore, the work head support tower 416 can move along the X-axis rail based on the rotation of a ball screw (not shown) accommodated in the X-axis rail 414 and the expansion / contraction of the laminated piezoelectric element.

In each work head support tower 416 in the figure, in the example shown in the figure, two work heads 418 are arranged so as to be movable up and down (Z direction) and rotatable in a 360 degree direction. A total of eight work heads 418 are arranged in the component mounting apparatus 400 of this example.
Each work head 418 moves the X-axis rail 414 horizontally in the Y-axis direction, horizontally moves the work head support tower 416 in the X-axis direction, and moves up and down in the Z-axis direction by the work head 418 itself. By rotating around the center, it is possible to freely change the position of the component supply position with respect to the front, rear, left, right, up and down between the printed circuit boards and the direction in the 360 degree direction in the horizontal plane.

Further, a suction nozzle for directly sucking the electronic component is attached to the tip of the work head 418, and the suction and release of the electronic component is directly performed at the tip of the suction nozzle.
In the electronic component mounting apparatus 400 configured as described above, the horizontal movement speed of the work head 418 by the rotation control of the ball screw is assisted by the thickness control of the laminated piezoelectric element, and the work head 418 is moved at high speed by computer control. The work head 418 is moved up and down during the time required to maintain the stopped state after the work head 418 is moved to the target position at high speed, and the electronic components are picked up from the parts supply position, It is possible to mount a component at a component mounting position on a printed circuit board.

  Further, the electronic component is picked up at the picked-up position, the picking state of the electronic component is picked up by the photographing camera 420 shown in FIG. 4, the image analysis is performed based on the picked up picked-up state, and the electronic component is picked up according to the analysis result. The component mounting procedure, such as correcting the position and angle and mounting the sucked electronic component on the printed circuit board, proceeds serially with respect to one electronic component, so that the high-speed operation of the work head 418 is realized as described above. By doing so, the processing between each procedure is shortened, in particular, the time from the image analysis to the mounting of the electronic component is shortened, and the production efficiency can be increased.

  Furthermore, since the work head 418 can reach the component supply position in a short time during component suction, the posture of the electronic component at the component supply position is photographed, and the position of the work head 418 is corrected until the electronic component is sucked by the suction nozzle. Thus, it is possible to accurately attract the center of a small electronic component.

  In addition, the accuracy of the electronic component suction at the component supply position and the mounting of the electronic component at the component mounting position on the printed board is improved. Various high-frequency vibrations are generated from the component devices of the component mounting device. For example, this applies when the X-axis rail 414 moves, when the work head support tower 416 moves, or when the work head moves up and down. The high-frequency vibration particularly acts on the tip of the suction nozzle, and causes a positional shift when the electronic component is sucked or mounted. Therefore, by constructing a displacement adjusting member such as the laminated piezoelectric element having a high response speed to weaken the feedback of the high frequency component, the high frequency vibration is absorbed by the displacement adjusting member so that highly accurate positioning can be realized. Become.

In the above example, the positioning mechanism is described as a mechanism having the X-axis rail 414 and the Y-axis rail 412. However, the positioning mechanism described above can be applied anywhere as long as the position is determined.
Further, the laminated piezoelectric element constituting the positioning mechanism is not limited to the position described above, and can be any position that can move the ball screw in the moving direction of the moving table (X-axis rail or work head support tower) when viewed from the absolute position. Any location can be appropriately configured.

Further, the absolute position of the moving table (X-axis rail or work head support tower) configured in the positioning mechanism can also be detected by configuring a small position detector that detects only the displacement of the laminated piezoelectric element.
In the above example, the laminated piezoelectric element having a high response speed is configured as the displacement adjusting member, but a voice coil motor, a pneumatic actuator, a stepping motor, or the like is also applied as a response speed is fast. The same effect as described above can be obtained.

It is an example of the positioning apparatus which is the best form for implementing this invention. FIG. 2 is a control block diagram for controlling the position of a moving table 20 in the positioning device 10 of FIG. 1. The graph shows the relationship between the position of the movement table 20 and the time at that position when the movement table 20 is moved. It is a perspective view of a component mounting apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Positioning device 11 First frame 12 Linear scale 13 Guide rail 14 Second frame 15 Multilayer piezoelectric element 16 Ball screw holding member 17 Ball screw 18 Servo motor 19 Coupling 20 Moving table 21 Nut 22 Bearing 23 Detector

Claims (7)

Position command means for issuing a command to move the moving body to the target position, and based on the position command means, the moving body is moved from the current position of the moving body to the target position, and the moving body is stopped at the target position. A positioning device having first position control means,
Comparing the position of the moving body that moves based on the first position control means and the target position, the moving body is moved to the target position only by the first position control means. A second position control means for assisting the movement of the moving body so that the moving body reaches the target position and the moving body is stopped at the target position;
A positioning device characterized by that. The second position control means moves the moving body by a moving distance of the moving body based on a command of the position command means or a predetermined distance within the moving distance when the moving body starts moving. After reaching the target position, the target position is not reached by the moving system of the first position control means based on the movement distance of the moving body or the movement of the predetermined distance by the second position control means. Auxiliary control is performed so that the moving body that is determined and continues to move by the first position control means moves in the direction opposite to the traveling direction of the moving body.
The positioning device according to claim 1. The second position control means advances or retracts a part or the whole of the moving system by the first position control means in the moving direction of the moving body by expansion or contraction of at least one piezoelectric element.
The positioning apparatus according to claim 1 or 2, wherein The first position control means is based on the rotation angle of the motor in a combination of a motor with a slow response speed but capable of high-speed rotation and a ball screw that changes the rotational power of the motor into a linear movement force of the moving body. To control the position of the moving body,
The second position control means controls the position of the moving body based on the absolute position of the moving body.
The positioning device according to any one of claims 1 to 3, wherein A component mounting apparatus that continuously performs a process of sucking and holding an electronic component on the work head and mounting the printed circuit board on a printed circuit board based on horizontal movement and up-and-down movement of the work head, targeting a plurality of electronic components,
Position command means for issuing a command to move the working head to a target position;
First position control means for horizontally moving the work head from the current position of the work head to the target position based on the position command means and stopping the work head at the target position;
Compared with the position of the working head that moves horizontally based on the first position control means and the target position, the work head is moved horizontally to the target position only by the first position control means. Second position control means for auxiliary control of horizontal movement of the work head so that the work head reaches the target position as soon as possible and the work head is stopped at the target position;
A component mounting apparatus characterized by comprising: The second position control means moves the work head by a movement distance of the work head based on a command of the position command means or a predetermined distance within the movement distance when the work head starts to move. After reaching the target position, the target position is not reached by the moving system of the first position control means based on the movement distance of the working head or the movement of the predetermined distance by the second position control means. Auxiliary control is performed so that the working head, which is judged and continues to move by the first position control means, moves in the direction opposite to the traveling direction of the working head.
The component mounting apparatus according to claim 5. The first position control means is based on a rotation angle of the servo motor configured in the servo motor in a combination of a servo motor and a ball screw that changes the rotational power of the servo motor into a linear movement force of the work head. To control the position of the working head,
The second position control means detects the absolute position of the working head with a linear scale, and a part or the whole of the moving system by the first position control means is expanded or contracted by at least one piezoelectric element. Moving forward or backward in the direction of movement of the working head,
The component mounting apparatus according to claim 5, wherein the component mounting apparatus is a component mounting apparatus.

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