JP2024099115A - Parts feeder - Google Patents

Abstract

To realize a parts feeder capable of smoothly transporting parts along a guide groove of a stage.
[Solution] The control unit 50 of the parts feeder 100 feedback controls the drive of the piezoelectric element 30 so that the waveform of the displacement of the stage 10 detected by the displacement sensor 40 exhibits a sawtooth shape, with a steep slope at the time when the movement of the stage 10 switches from one direction to the other direction and a gradual slope before and after the time when the movement of the stage 10 switches from the other direction to the one direction, thereby making it possible to transport the part P by sliding it in one direction along the guide groove 10a of the stage 10.
[Selected figure] Figure 2

Description

The present invention relates to a piezoelectric parts feeder.

2. Description of the Related Art Conventionally, there has been known a parts feeder that utilizes a piezoelectric element to transport an object such as an electronic component (see, for example, Japanese Patent Application Laid-Open No. 2003-233636).
This parts feeder vibrates a stage by driving a bimorph type piezoelectric element, thereby transporting electronic parts on the stage.

JP 2004-67360 A

However, in the case of the parts feeder of Patent Document 1, the vibration direction of the bimorph-type piezoelectric element is parabolic and the stage moves in an elliptical orbit, so that electronic components may bounce or rotate on the stage while being transported, which may result in damage to or cracks in the electronic components.
In particular, when the object to be transported is a micro component, there is a problem in that the micro component may adhere to the stage and become unable to move, or the micro component may gather together and clog the transport path.

The object of the present invention is to provide a parts feeder that can smoothly transport objects such as parts.

In order to achieve the above object, the present invention provides a parts feeder, comprising:
a stage having a guide groove on an upper surface thereof aligned along a predetermined direction in which the component is transported, the stage being elastically supported on a support base by an elastic member so as to be movable in the extending direction of the guide groove;
a piezoelectric element disposed in contact with the stage and configured to move the stage along the predetermined direction;
a displacement sensor that detects a displacement of the stage moving along the predetermined direction;
Equipped with
the piezoelectric element is configured to be capable of driving the stage to move at least in one direction along the predetermined direction at one speed, and to drive the stage to move at least in another direction along the predetermined direction at another speed faster than the one speed,
A control unit is provided which feedback controls the drive of the piezoelectric element (expansion and contraction of the piezoelectric element) so that the waveform of the displacement of the stage detected by the displacement sensor has a sawtooth shape, with a steep slope at the timing when the movement of the stage switches from the one direction to the other direction and a gradual slope before and after the timing when the movement of the stage switches from the other direction to the one direction.

In a parts feeder having such a configuration, when the stage is moved in one direction at a relatively slow speed, a static friction force acts between the guide groove of the stage and the part, causing the part to adhere to the stage and move integrally with the stage (static friction mode; adhesion mode).
On the other hand, when the stage is moved in another direction at a relatively high speed, a dynamic friction force acts between the guide groove of the stage and the part, and the part slides in the guide groove due to inertia so as to maintain its relative position in the part feeder, and moves relatively in one direction on the stage (dynamic friction mode; sliding mode).
By repeating such static friction mode (adhesion mode) and dynamic friction mode (sliding mode), the part is transported so as to slide in one direction along the guide groove of the stage.
In particular, by feedback controlling the drive of the piezoelectric element so that the waveform of the stage displacement detected by the displacement sensor exhibits a sawtooth shape, with a steep slope at the time when the stage movement switches from one direction to the other and a gradual slope before and after the time when the stage movement switches from the other direction to the one direction, the part can slide more smoothly along the guide groove of the stage, and the part can be transported smoothly.

Also preferably,
The elastic member is configured to have a restoring force generated when it is restored to its original shape after being elastically deformed as the stage is moved in the one direction, and this restoring force serves as a driving force for moving the stage in the other direction.
With this arrangement, it becomes possible to move the stage in other directions more quickly.

Also preferably,
When the stage is viewed in cross section along a plane perpendicular to the predetermined direction, the guide groove is formed so that its side surface opens upward.
If the guide groove has a side surface that opens upward, the parts moving along the guide groove will not rub against the side surface, and the parts will move more smoothly.

Also preferably,
A ground is provided on the stage, and at least the guide groove is configured to be prevented from becoming charged.
Also preferably,
A demagnetizer is installed on the stage, and is configured so that at least the guide groove is not magnetized.
Also preferably,
A heater is provided on the stage so that at least the guide groove is kept dry (at least no condensation occurs in the guide groove).
With a stage configured in this way, the parts can move smoothly along the guide grooves.

According to the present invention, parts can be transported smoothly along the guide grooves of the stage.

FIG. 2 is a schematic top view showing the part feeder of the present embodiment. FIG. 2 is a schematic side view showing the part feeder of the present embodiment. 11 is an explanatory cross-sectional view of a guide groove provided in a stage. FIG. FIG. 1A is an example of a control signal input to a piezoelectric element by a control unit of a parts feeder, and FIG. 1B is an explanatory diagram of the movement of a stage and the transportation of parts in response to the control signal. 5 is an explanatory diagram relating to a control signal for driving a piezoelectric element and a response of a stage. FIG. 1A shows a waveform of a stage displacement in the parts feeder of this embodiment, and FIG. 1B shows a waveform of a velocity corresponding to the displacement waveform, and FIG. 1C shows a waveform of an acceleration corresponding to the displacement waveform.

The following describes in detail an embodiment of a parts feeder according to the present invention with reference to the drawings. However, the embodiment described below has various limitations that are technically preferable for implementing the present invention, but the scope of the present invention is not limited to the following embodiment and illustrated example.

As shown in Figures 1 and 2, the parts feeder 100 of this embodiment includes a stage 10 having a guide groove 10a on its upper surface that is aligned with a predetermined direction in which parts P are transported, an elastic member 20 that elastically supports the stage 10 on a support base B so that the stage 10 can be moved in the extension direction of the guide groove 10a, a piezoelectric element 30 that moves the stage 10 along the predetermined direction, a displacement sensor 40 that detects the displacement of the stage 10 moving along the predetermined direction, and a control unit 50 that feedback controls the drive of the piezoelectric element 30 in response to the displacement of the stage 10 detected by the displacement sensor 40.
The parts P conveyed by the parts feeder 100 are, for example, minute parts measuring 0.2 mm square and 0.4 mm long (04×02), or 0.1 mm square and 0.2 mm long (02×01).

The stage 10 is, for example, a flat metal member, and has a guide groove 10a formed on the upper surface thereof along a predetermined direction.
When the stage 10 is viewed in cross section along a plane perpendicular to a predetermined direction, the guide groove 10a is formed so that the side surface of the guide groove 10a opens upward, as shown in FIG.
If the side surface of the guide groove 10a opens upward, the part P moving along the guide groove 10a will not rub against the side surface, and the part will move more smoothly.

The elastic members 20 are, for example, leaf springs that are substantially L-shaped when viewed from above, and are provided at the four corners of the stage 10 .
One end of a generally L-shaped elastic member 20 is fixed to the stage 10, and the other end is fixed to the support base B. The one end of the elastic member 20 is the portion that undergoes elastic deformation.
The elastic member 20 elastically supports the stage 10 on the support base B so that the stage 10 is movable in a substantially horizontal direction.

The piezoelectric element 30 is fixed onto a support base B, and a drive portion of the piezoelectric element 30 is disposed in contact with one side surface of the stage 10 (the left side surface in the drawing).
Lead wires for applying a voltage are connected to the piezoelectric element 30, and the piezoelectric element 30 expands when a voltage is applied to the piezoelectric element 30.
The expanded piezoelectric element 30 moves the stage 10 in one direction (to the right in the figure) as if pushing it out, and the contracted piezoelectric element 30 moves the stage 10 in the other direction (to the left in the figure) as if pulling it back.
This piezoelectric element 30 is configured to be capable of driving the stage 10 to move in one direction along a predetermined direction (to the right in the figure) at one speed, and to move the stage 10 in another direction along the predetermined direction (to the left in the figure) at another speed faster than the first speed.

In addition, the piezoelectric element 30 is configured so that the restoring force of the elastic member 30, which is elastically deformed when the stage 10 is moved in one direction by the piezoelectric element 30, acts as a driving force to move the stage 10 in the other direction (leftward in the figure).

The stage 10 is designed so that its center of gravity is on a line of action L along which the piezoelectric element 30 exerts a driving force to move the stage 10 . The piezoelectric element 30 and the stage 10 are placed on a support base B.
With this structure, the movement of the stage 10 can be stabilized.

The displacement sensor 40 is fixed onto a support base B, and is disposed on the other side (the right side in the figure) of the stage 10 at a position spaced apart from the stage 10 .
In other words, the piezoelectric element 30 and the displacement sensor 40 are disposed opposite to each other with the stage 10 interposed therebetween.
The displacement sensor 40 is, for example, a capacitance type displacement sensor, and detects the displacement of the stage 10 which moves in the horizontal direction as a result of being driven by the piezoelectric element 30 .
The displacement sensor 40 here detects the displacement of the stage 10 moving toward and away from the displacement sensor 40 .

The control unit 50 has, for example, a CPU, a ROM, a RAM, etc., and is a controller that generally controls each unit through cooperation between the CPU and program data stored in the ROM expanded in the working area of the RAM.
2, the control unit 50 is connected to the displacement sensor 40 via a displacement sensor amplifier 41. The control unit 50 is also connected to the piezoelectric element 30 via a piezo driver 31.
As described below, the control unit 50 of the parts feeder 100 of this embodiment is configured to feedback control the drive of the piezoelectric element 30 so that the waveform of the displacement of the stage 10 detected by the displacement sensor 40 exhibits a sawtooth shape, with a steep slope at the time when the movement of the stage 10 switches from one direction to the other direction, and a gradual slope before and after the time when the movement of the stage 10 switches from the other direction to the one direction.

Next, we will explain how the part feeder 100 of this embodiment transports the part P.

For example, based on a command from an external higher-level control device, a control signal having the waveform shown in FIG. 4( a) is input to the control unit 50, and a voltage according to the command value of the control signal is applied to the piezoelectric element 30 via the piezo driver 31.
As shown in FIG. 4( b ), the piezoelectric element 30 to which a voltage corresponding to this control signal has been applied moves the stage 10 in one direction (to the right in the figure) at one speed ((1)-(2)), then moves the stage 10 in the other direction (to the left in the figure) at another speed faster than the first speed ((2)-(3)), and then moves the stage 10 in the one direction at the one speed ((3)-(4)), and then moves the stage 10 in the other direction at another speed faster than the first speed ((4)-(5)).

When the stage 10 moves in one direction (to the right in the figure) at a relatively slow speed ((1)-(2), (3)-(4)), a static friction force acts between the guide groove 10a of the stage 10 and the part P, causing the part P to move integrally with the stage 10 (static friction mode; adhesion mode).
On the other hand, when the stage 10 moves in another direction (leftward in the figure) at a relatively high speed ((2)-(3), (4)-(5)), a kinetic friction force acts between the guide groove 10a of the stage 10 and the part P, and the part P slides in the guide groove 10a due to inertia so as to maintain its relative position in the part feeder 100, and moves in one direction relatively on the stage 10 (kinetic friction mode; sliding mode).
In other words, by inputting a control signal having this waveform ( FIG. 4( a )) to the control unit 50 and driving the piezoelectric element 30 to expand and contract, a static friction mode (adhesion mode) in which the stage 10 is moved in one direction at one speed (low speed) where a static friction force acts between the guide groove 10 a of the stage 10 and the part P, and a kinetic friction mode (sliding mode) in which the stage 10 is moved in the other direction at another speed (high speed) where a kinetic friction force acts between the guide groove 10 a of the stage 10 and the part P are repeated.
By repeating the static friction mode and the dynamic friction mode, the part P is transported so as to slide in one direction (to the right in the figure) along the guide groove 10a on the stage 10.

When the waveform of the control signal is a sawtooth waveform as shown in FIG. 4(a), the waveform of the displacement of the stage 10 moved by the piezoelectric element 30 to which a voltage corresponding to the command value of the control signal is applied is detected by the displacement sensor 40 as a sawtooth waveform similar to the waveform of the control signal.

Incidentally, when the stage 10 is moved in one direction by the piezoelectric element 30 to which a voltage corresponding to the command value of the control signal has been applied, if the speed (acceleration) at which the piezoelectric element 30 expands is large, this can result in an impact that causes natural vibration of the stage 10 (see the upper part of Figure 5).
If such natural vibration occurs, the component P may bounce off the stage 10, making it impossible for the component P and the stage 10 to move together.
For example, if such natural vibration occurs, the movement of the stage 10 will deviate from that based on the control signal, and the transportation of the part P will become uneven. Therefore, the generation of natural vibration of the stage 10 is suppressed by feedback controlling the drive of the piezoelectric element 30 (see the lower part of Figure 5).
In particular, when the stage 10 is moved in one direction after having been moved in another direction, the sudden change in the direction of movement is likely to cause an impact, resulting in natural vibration of the stage 10. Therefore, the generation of natural vibration of the stage 10 is suppressed by feedback controlling the drive of the piezoelectric element 30.
Furthermore, the control unit 50 may be provided with a notch filter circuit, and the natural vibration of the stage 10 may also be suppressed by waveform control using the notch filter.

Next, regarding the conveyance of the parts P by the parts feeder 100 of this embodiment, feedback control of the drive of the piezoelectric element 30 will be described with reference to FIG.
In FIG. 6A, one of the sawtooth waveforms is shown as the waveform of the displacement of the stage 10, but this waveform is repeated to form the sawtooth waveform.

As mentioned above, when the stage 10 is moved in one direction by the piezoelectric element 30 to which voltage is applied, if the speed (acceleration) at which the piezoelectric element 30 expands is large, this can cause an impact and result in natural vibration of the stage 10.
In order to prevent this inherent vibration from occurring, it is preferable to reduce the magnitude of the acceleration of the stage 10 before and after the timing at which the stage 10 switches from a kinetic friction mode, in which the stage 10 moves in the other direction, to a static friction mode, in which the stage 10 moves in one direction (for example, the acceleration at the timings (d) and (b) in Figure 6).
Therefore, in this embodiment, the driving of the piezoelectric element 30 is controlled so that the stage 10 moves relatively slowly at the timing when the dynamic friction mode ends (timing (d)-(e) in FIG. 6(a)) and the timing when the static friction mode starts (timing (a)-(b) in FIG. 6(a)).
Specifically, a function for editing the control waveform so as to reduce the magnitude of the acceleration of the stage 10 is added to the control unit 50 .

To achieve this, the control unit 50 feedback-controls the drive of the piezoelectric element 30 so that the slope of the displacement waveform when the movement of the stage 10 switches from another direction (dynamic friction mode) to one direction (static friction mode) becomes gentle ((iv)-(e), (a)-(b) in FIG. 6(a)).
Specifically, the control waveform is edited and the drive of the piezoelectric element 30 is feedback-controlled so that the slope of the displacement waveform in the latter half of the kinetic friction mode ((D)-(E) in FIG. 6(a)) is gentler than the slope of the displacement waveform in the first half of the kinetic friction mode ((C)-(D) in FIG. 6(a)) and the slope of the displacement waveform at the beginning of the static friction mode ((A)-(B) in FIG. 6(a)) is gentler than the slope of the displacement waveform in the subsequent static friction mode ((B)-(C) in FIG. 6(a)).

In order to clearly switch from the static friction mode to the kinetic friction mode, it is preferable to move the stage 10 with a sudden speed change in the opposite direction. In other words, it is preferable to move the stage 10 with a large acceleration that instantaneously changes the direction in the opposite direction.
Therefore, in this embodiment, at the timing when the static friction mode is switched to the dynamic friction mode (timing (c) in FIG. 6(a)), the driving of the piezoelectric element 30 is controlled so that the stage 10 suddenly changes direction from one direction to the other and moves at high speed.

To achieve this, the control unit 50 feedback-controls the drive of the piezoelectric element 30 so that the slope of the displacement waveform becomes steep when the movement of the stage 10 switches from one direction (static friction mode) to the other direction (kinetic friction mode) ((c) in FIG. 6(a)).
Specifically, the control waveform is edited so that the slope of the waveform of the initial displacement in the dynamic friction mode ((c) in FIG. 6(a)) becomes approximately vertical, and the drive of the piezoelectric element 30 is feedback-controlled.
More specifically, the control waveform is adjusted so that the slope of the displacement waveform becomes steeper (acceleration becomes large) when the movement of the stage 10 switches from one direction (static friction mode) to the other direction (kinetic friction mode) (FIG. 6(a)(c)). At that time, the control waveform is edited while referring to the magnitude of the acceleration signal of the stage. The acceleration signal is generated by processing the displacement sensor signal.
Here, the control waveform is edited so that the slope of the waveform of the initial displacement in the dynamic friction mode ((c) in FIG. 6(a)) becomes approximately vertical.

In other words, in this embodiment, feedback control is performed using the displacement sensor 40 so that the stage 10 moves according to the control signal, and the control signal is edited while referring to the acceleration signal of the stage 10 in order to preferably switch between the static friction mode (adhesion mode) and the kinetic friction mode (slip mode).

Then, by feedback controlling the drive of the piezoelectric element 30 so that the waveform of the displacement of the stage 10 detected by the displacement sensor 40 exhibits the waveform of the solid line shown in Fig. 6(a), it is possible to suitably switch between the static friction mode and the dynamic friction mode, and the part P can be suitably transported along the guide groove 10a of the stage 10. (The waveform of the dashed line in Fig. 6(a) is similar to the model waveform shown in Fig. 4(a).)
In addition, when the drive of the piezoelectric element 30 is feedback-controlled so that the waveform of the displacement of the stage 10 detected by the displacement sensor 40 exhibits the solid line waveform shown in FIG. 6(a), it can be said that an external higher-level control device inputs a control signal similar to the solid line waveform shown in FIG. 6(a) to the control unit 50 and applies a voltage corresponding to the command value of the control signal to the piezoelectric element 30 via the piezo driver 31, thereby moving the stage 10.
In addition, the control unit 50 may internally hold multiple pieces of control signal waveform pattern information similar to the solid line waveform shown in Figure 6 (a), and an external higher-level control device may select the waveform pattern and switch the waveform output ON/OFF, and output a waveform output timing signal (repetition frequency), thereby moving the stage 10.

In this way, by feedback controlling the drive of the piezoelectric element 30 so that the waveform of the displacement of the stage 10 detected by the displacement sensor 40 is not a simple sawtooth waveform (the dashed line waveform in FIG. 6(a)) but rather the solid line waveform shown in FIG. 6(a), the part P can be transported by sliding it in one direction (to the right in the figure) along the guide groove 10a on the stage 10.
In other words, the component P on the stage 10 is not transported in a bouncing manner, and therefore the component P being transported is not damaged or otherwise defective.
In particular, if the part P being transported by the part feeder 100 is a very small part, even slight vibrations can cause the part P to bounce. However, the part feeder 100 of this embodiment can appropriately switch between static friction mode and dynamic friction mode, allowing even the smallest part P to be transported by sliding it across the stage 10.

It should be noted that by using a control signal having an inverted control waveform of the control signal shown in FIG. 6A, the transport direction of the part P being moved on the stage 10 can be reversed.
For example, by moving the stage 10 in another direction (leftward in the figure) at a relatively slow speed (static friction mode; adhesion mode), and then moving the stage 10 in one direction (rightward in the figure) at a relatively high speed (dynamic friction mode; sliding mode), the transport direction can be switched so that the part P on the stage 10 is moved in the other direction.
If the transport direction of the parts P could be switched to the opposite direction, when multiple parts P become clogged in the guide groove 10a, the control signal (control waveform) could be switched to temporarily reverse the transport direction of the parts P, thereby clearing the clog.

The present invention is not limited to the above-described embodiment.
For example, a ground (not shown) may be provided on the stage 10 .
If the guide groove 10a is configured so that it is not charged by the ground, this is preferable because it allows the component P to move smoothly along the guide groove 10a.

In addition, a demagnetizer (not shown) may be installed on the stage 10.
If the guide groove 10a is configured so as not to become magnetized by the demagnetizer, this is preferable because it allows the part P to move smoothly along the guide groove 10a.

In addition, a heater (not shown) may be installed on the stage 10 .
It is preferable to use the heater to warm the guide groove 10a (stage 10) and evaporate moisture from the surface of the guide groove 10a so that the guide groove 10a is kept dry, as this allows the part P to move smoothly along the guide groove 10a.
In addition, if the heater is configured to make the temperature of the guide groove 10a approximately the same as the temperature in the room in which the parts feeder 100 is installed, thereby preventing condensation from forming in the guide groove 10a, this is preferable as it allows the parts P to move smoothly along the guide groove 10a.

In addition, to prevent charging, static electricity, and magnetism, the stage 10 may be made of a non-magnetic material such as ceramics.

The application of the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

REFERENCE SIGNS LIST 10 stage 10a guide groove 20 elastic member 30 piezoelectric element 40 displacement sensor 50 control unit 100 parts feeder B support base P part L line of action

Claims (6)

a stage having a guide groove on an upper surface thereof aligned along a predetermined direction in which the component is transported, the stage being elastically supported on a support base by an elastic member so as to be movable in the extending direction of the guide groove;
a piezoelectric element disposed in contact with the stage and configured to move the stage along the predetermined direction;
a displacement sensor that detects a displacement of the stage moving along the predetermined direction;
Equipped with
the piezoelectric element is configured to be capable of driving the stage to move at least in one direction along the predetermined direction at one speed, and to drive the stage to move at least in another direction along the predetermined direction at another speed faster than the one speed,
a control unit that feedback controls the drive of the piezoelectric element so that the waveform of the displacement of the stage detected by the displacement sensor has a sawtooth shape, with a steep slope at the timing when the movement of the stage switches from the one direction to the other direction and a gradual slope before and after the timing when the movement of the stage switches from the other direction to the one direction. The parts feeder according to claim 1, characterized in that the restoring force of the elastic member, which is elastically deformed as the stage is moved in the one direction, becomes a driving force for moving the stage in the other direction. The parts feeder according to claim 1 or 2, characterized in that, when the stage is viewed in cross section on a plane perpendicular to the predetermined direction, the guide groove is formed so that its side surface opens upward. The parts feeder according to claim 1 or 2, characterized in that a ground is provided on the stage, and at least the guide groove is configured to prevent charging. The parts feeder according to claim 1 or 2, characterized in that a demagnetizer is installed on the stage, and at least the guide groove is configured to be demagnetized. The parts feeder according to claim 1 or 2, characterized in that a heater is installed on the stage, and at least the guide groove is configured to be dry.

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