JP4548030B2 - Liquid dispensing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed amount of liquid ejecting apparatus which can eject fixed amount of liquid with good accuracy and can prevent liquid sagging and stringiness. <P>SOLUTION: The fixed amount of liquid ejecting apparatus is provided with a housing chamber 11 for housing liquid, an extrusion piston 15 for extruding liquid housed in the housing chamber to an exhaust port by every predetermined volume, a 1st passage 21 having an ejection nozzle 26 for ejecting the liquid at one end and an opening 25 at a flank, a 2nd passage 19 which connects the opening of the 1st passage with the exhaust port of the housing chamber, an ejection piston 22 which reciprocates in the 1st passage with freely sliding to open/close the opening 25 and to eject whole amount of the liquid in the 1st passage 21 from the ejection nozzle 26 and an ultrasonic wave application means 23 which applies ultrasonic vibration to the ejection nozzle 26 to heighten discreteness of the liquid from the ejection nozzle. Since the ejection piston 22 plays a role of a valve for preventing spillover of the liquid in the housing chamber 11, whole amount of the liquid in the 1st passage 21 can be ejected with accuracy without being influenced by residual amount and viscosity change of the liquid in the housing chamber 11. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

The present invention relates to a liquid dispensing apparatus suitable for dispensing a viscous liquid such as a conductive paste, an adhesive, and a solder paste intermittently in a constant amount.

2. Description of the Related Art Conventionally, a quantitative discharge device as described in Patent Document 1 is known as a device that accurately discharges a predetermined amount of liquid such as liquid resin or adhesive onto the surface of an electronic component or the like.
As shown in FIG. 3, the fixed volume discharge device is configured to discharge a predetermined amount of the liquid 50 in the syringe 52 by filling the syringe 52 with the liquid 50 and pushing the piston 54. The piston 54 is driven by a stepping motor 56 and a ball screw 58, for example. By rotating the stepping motor 56 by the number of steps corresponding to the required supply amount of the liquid 50, the piston 54 is moved downward in the figure, and the liquid 50 is discharged from the tip of the discharge nozzle 53.
Japanese Patent Laid-Open No. 5-34184

In the case of such a quantitative discharge device, even if a fixed amount of liquid is pushed out by the piston 54, the amount of liquid actually applied is not constant due to the influence of various conditions. That is, since the liquid remains in the discharge nozzle 53 due to the viscosity, surface tension, etc. of the liquid, the amount actually applied to the object to be coated is subtracted from the amount pushed out by the piston 54 that remains in the discharge nozzle 53. Amount. The portion remaining in the discharge nozzle 53 is not constant, and application variation occurs. Further, due to the residual pressure of the liquid existing in the syringe 52, the liquid continues to flow out even when the piston 54 is stopped, and a certain amount of time is required until the liquid outflow is completed. Therefore, if the discharge nozzle 53 is lifted immediately after the piston 54 is stopped, the actual application amount becomes smaller than the target application amount, and a problem of dripping or stringing occurs from the raised nozzle 53 occurs.

Further, as another quantitative discharge device, Patent Document 2 proposes a device for applying an adhesive at a predetermined position on an electronic circuit board. In this apparatus, an ultrasonic vibrator 61 is attached in the vicinity of the discharge nozzle 60 as shown in FIG. 4, and the ultrasonic wave emitted from the ultrasonic vibrator 61 is applied to the substrate 64 while reducing the viscosity of the adhesive 62. By applying, application variation due to stringing is eliminated.
JP-A-5-220433

By applying the adhesive 62 while reducing the viscosity of the adhesive 62, the stringing property is reduced. However, since the passage connecting the container 63 containing the adhesive 62 and the discharge nozzle 60 is always open, the viscosity of the adhesive 62 is reduced. There is a problem that the discharge amount greatly varies under the influence of the change and the remaining amount of adhesive in the container 63. Further, since the ultrasonic vibration propagates not only to the discharge nozzle 60 but also to the container 63, the viscosity of the adhesive in the container 63 is also reduced, which causes deterioration of the discharge accuracy. As a result, quantitativeness cannot be guaranteed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid dispensing apparatus that can discharge liquid with a certain amount of accuracy and can prevent dripping and stringing.

In order to achieve the above object, the present invention includes a storage chamber for storing a liquid and having a discharge port for the liquid , and a reciprocating slidable movement in the storage chamber to discharge the liquid stored in the storage chamber. An extrusion piston that extrudes a predetermined amount at a time, a discharge nozzle that discharges liquid at one end, a first passage having an opening on a side surface, an opening of the first passage, and a discharge port of the storage chamber The second passage to be connected and the inside of the first passage are slidably reciprocated, the opening is opened at the retracted position, the opening is closed at the advanced position, and the liquid in the first passage is closed. A discharge piston that discharges the entire amount from the discharge nozzle; a drive unit that drives the discharge piston to reciprocate; and an ultrasonic application unit that applies ultrasonic vibration to the discharge nozzle to improve the separation of the liquid from the discharge nozzle. Liquid characteristics characterized by To provide a discharge device.

In the present invention, first, with the discharge piston retracted, the liquid is pushed out from the storage chamber by a predetermined amount by the push-out piston . The extruded liquid flows through the second passage from the opening of the first passage into the first passage. Next, when the discharge piston is advanced, the opening is closed by the discharge piston, and the liquid flowing into the first passage is separated from the second passage and forcibly discharged from the discharge nozzle. In other words, since the discharge piston serves as a valve that prevents the liquid from flowing out of the storage chamber, the total amount of the liquid in the first passage can be accurately measured without being affected by the remaining amount of the liquid in the storage chamber or a change in viscosity. Can be discharged from the discharge nozzle.
Further, the entire amount of the liquid in the first passage is discharged by the discharge piston, but there is a possibility that the liquid may remain on the front end surface or the side surface of the discharge nozzle, or dripping or stringing may occur. However, since an ultrasonic application means for applying ultrasonic vibration to the discharge nozzle is provided, it is easy to separate the liquid from the discharge nozzle, and it is possible to prevent the liquid from remaining and also prevent the occurrence of dripping and stringing. it can.
The ultrasonic vibration may propagate not only to the discharge nozzle but also to the second passage and the storage chamber. Even in that case, since the discharge piston closes the opening of the first passage, the liquid is prevented from flowing out from the second passage to the first passage, and the discharge accuracy is not lowered.
From the above, liquid can be ejected with a certain amount of accuracy, and dripping and stringing can be prevented.

Vibration suppression means comprising an elastic body that suppresses propagation of ultrasonic vibration generated by the ultrasonic wave application means to the accommodating chamber between the member constituting the second passage and the member constituting the first passage. The member constituting the second passage may be formed of a soft material that suppresses propagation of ultrasonic vibration generated by the ultrasonic wave application means to the storage chamber.
As described above, since the discharge piston closes the opening of the first passage, the liquid does not flow into the first passage even if the ultrasonic vibration propagates to the storage chamber. When the viscosity changes and the liquid in the storage chamber is pushed out to the first passage by the pushing means, there is a possibility that the inflow amount is affected.
This problem can be solved by providing vibration suppression means for suppressing propagation of ultrasonic vibration in the second passage.
The vibration suppressing means can be configured, for example, by interposing an elastic means such as an O-ring between a member constituting the first passage and a member constituting the second passage. It is effective to arrange the O-ring in a direction perpendicular to the direction of ultrasonic vibration. In addition, the propagation of ultrasonic vibration can be suppressed by forming the member constituting the second passage with a soft material such as a resin material.

A liquid storage container for storing the liquid is provided, and a pressurizing means for applying and pushing a predetermined pressure to the liquid in the liquid storage container is provided, and the liquid pushed out of the liquid storage container by the pressurizing means is guided to the storage chamber. the passageway is provided, the extrusion piston to push through the discharge port by a predetermined amount of liquid accommodating chamber each time advances one step, the controllable drive means the amount of movement of the extrusion piston is provided, in the middle of the third passageway The storage chamber may be provided with opening / closing means that is opened only when the liquid is replenished from the liquid storage container.
By providing a liquid storage container upstream of the storage chamber and connecting the liquid storage container and the storage chamber via the third passage, when the liquid in the storage chamber becomes empty, the liquid storage container is replenished. This makes it possible to continuously perform liquid discharge a large number of times. In addition, since it is not necessary to store a large amount of liquid in the storage chamber, the volume can be limited to a volume that is less affected by the compressibility of the liquid and the remaining amount. For example, if the volume of the storage chamber is set to several times to several hundred times the discharge amount at one time, the influence of the liquid compressibility and the remaining amount can be reduced. Since the third passage connecting the liquid storage container and the storage chamber is provided with an opening / closing means, when operating the extrusion piston, the liquid does not flow back to the liquid storage container side, and the pressure in the storage chamber is reduced. It is not affected by the amount of liquid remaining or the liquid pressure in the liquid storage container.
When the push-out piston is advanced, the discharge piston is set in the retracted position, so that the liquid in the storage chamber flows into the first passage through the second passage without resistance. Since the amount of liquid flowing into the first passage is determined by the amount of one advancement of the extrusion piston, the amount of one discharge can be accurately set by controlling the amount of one advancement of the extrusion piston with high accuracy. it can.

As a driving means for reciprocatingly driving the discharge piston and the extrusion piston, various direct acting actuators such as a combination of an electric motor and a ball screw, a fluid pressure cylinder, and a voice coil motor can be used.
Of these, it is desirable to use a voice coil motor as the driving means for driving the extrusion piston. For the control of the push-out piston, it is desirable to perform not only the position control but also the speed control and the thrust control at the same time, because such a control can be easily performed with a boil coil motor.

As described above, according to the present invention, by moving the discharge piston forward, the opening is closed and the liquid flowing into the first passage is separated from the second passage. Only the liquid in the first passage is discharged from the discharge nozzle without being affected by the change in the viscosity of the liquid. In addition, since the entire amount of the liquid in the first passage is discharged by the stroke of the discharge piston, it is possible to always maintain a certain amount of discharge accuracy.
In addition, since ultrasonic application means for applying ultrasonic vibration to the discharge nozzle is provided, it is possible to improve the separation of the liquid from the discharge nozzle, prevent the liquid from remaining in the discharge nozzle, Generation of whispering can also be prevented.
Further, even if ultrasonic vibration propagates to the storage chamber, the discharge piston is closed between the first passage and the second passage, so that liquid outflow from the storage chamber is prevented and discharge accuracy is reduced. There is nothing.

Embodiments of the present invention will be described below with reference to examples.

FIG. 1 shows an example of a liquid dispensing apparatus according to the present invention.
This fixed quantity discharge device is composed of a storage part A, a metering part B, and a discharge part C, and is attached to a movable part of a robot. By operating the robot in the X, Y, and Z directions, a discharge nozzle 26 (to be described later) can be moved directly above the application target W.

The storage part A includes a liquid storage container 1 called a syringe that stores the liquid L, a piston 2 that pushes out the liquid L, and a pressurizing means 3 such as an air cylinder. The pressurizing means 3 applies a constant pressure in the pushing direction to the piston 2 to push out the liquid L from the liquid storage container 1 at a constant pressure. The outlet part 4 of the liquid storage container 1 is connected to the measuring part B via the third passage 5.

The measuring unit main body 10 constituting the measuring unit B is provided with a tubular measuring chamber (accommodating chamber) 11 in the vertical direction, and the third passage 5 is connected to the measuring chamber 11 from the lateral direction. A connecting portion between the measuring chamber 11 and the passage 5 is an inflow port 12, and a lower end portion of the measuring chamber 11 is an outlet 13. The inlet 12 is preferably provided below the bottom dead center of the extrusion piston 15. The cross-sectional area of the measuring chamber 11 is set to be larger than that of the first passage 21 to be described later so that the measuring chamber 11 has a volume that is several times to several hundred times as large as one discharge amount. In the middle of the third passage 5, there is provided an opening / closing valve 14 that is opened only when the liquid L is replenished from the reservoir A to the measuring chamber 11. The on-off valve 14 of this embodiment is a rotary valve. However, as long as the valve can be switched between the open position and the closed position, a spool valve that moves in the axial direction to open and close the passage and other valves can be used. Good.

An extrusion piston 15 is inserted into the measuring chamber 11 so as to be slidable in the vertical direction. The head of the extrusion piston 15 is connected to a drive device 17 via an operating arm 16. In this embodiment, a voice coil motor that can accurately control the movement amount of the extrusion piston 15 and can freely control the movement speed of the extrusion piston 15 is used as the driving device 17. The amount of movement of the extrusion piston 15 for one time determines the single discharge amount of the liquid L. The amount of movement of the extrusion piston 15 is detected and fed back by a displacement sensor such as a linear encoder attached to the voice coil motor 16. The discharge port 13 of the measuring chamber 11 is connected to the discharge part C via a second passage 19 provided in the connecting member 18. As the extrusion piston 15 descends, the liquid in the measuring chamber 11 is pushed out from the discharge port 13 to the second passage 19. As the connecting member 18, a resin material such as a fluororesin may be used in order to suppress the propagation of ultrasonic vibration from an ejection head 20 described later.

The discharge section C includes a discharge head 20 that is slidably supported in the vertical direction in the support hole 18a of the connecting member 18, a first passage 21 that is formed through the central portion of the discharge head 20 in the vertical direction, and a first passage 21. The discharge piston 22 is slidably inserted into the passage 21, a donut-shaped ultrasonic vibrator 23 fixed to the upper end of the discharge head 20, and a drive device 24 that strokes the discharge piston 22 up and down. ing. The upper end portion of the discharge piston 22 passes through the ultrasonic vibrator 23 and is connected to the drive device 24. As the driving device 24, various actuators such as a combination of an electric motor and a ball screw, a fluid pressure cylinder, and a voice coil motor can be used. Here, an air cylinder is used. In the middle of the first passage 21, an opening 25 that opens in the lateral direction is provided, and the second passage 19 is connected to the opening 25. The opening 25 is closed when the discharge piston 22 is in the forward position (bottom dead center), and the opening 25 is opened when the discharge piston 22 is in the backward position (top dead center). In particular, the opening 25 is preferably provided in the vicinity of the top dead center of the discharge piston 22. An integrated or separate discharge nozzle 26 is provided at the lower end of the discharge head 20, and when the discharge piston 22 is at the bottom dead center, the tip of the discharge piston 22 is positioned substantially at the same position as the tip of the discharge nozzle 26. It has been adjusted to be. The ejection head 20 also serves as an ultrasonic horn that expands the amplitude of the ultrasonic vibration generated by the ultrasonic transducer 23 and transmits it to the ejection nozzle 26.

The discharge head 20 is fitted in a support hole 18 a provided in the connecting member 18 so as to be movable up and down, and an O-ring 27 for preventing liquid leakage is provided between the discharge head 20 and the connecting member 18. ing. The O-ring 27 is disposed in a direction that allows the displacement in the vibration direction of the ultrasonic transducer 23 to be suppressed, and the ultrasonic vibration is prevented from propagating from the ejection head 20 to the measuring unit B via the connecting member 18. Also plays a role.
Here, an example in which the direction of ultrasonic vibration is the vertical direction is shown, but it may be a horizontal direction.

Next, the operation of the liquid dispensing apparatus will be described with reference to FIG.
First, as shown in FIG. 2A, the discharge piston 22 is set to the bottom dead center position, the opening 25 is closed, the push piston 15 is raised to the top dead center, and the open / close valve 14 is opened. Therefore, the liquid L pushed out from the liquid storage container 1 at a constant pressure passes through the third passage 5 and is introduced into the measuring chamber 11 from the inlet 12. At this time, by reducing the product of the rising speed of the extrusion piston 15 and the cross-sectional area of the piston 15 compared to the flow rate supplied from the liquid storage container 1, it is possible to prevent the inside of the measuring chamber 11 from becoming negative pressure, Generation of bubbles can be prevented. Thus, the measuring chamber 11 is filled with the liquid L.

Next, as shown in FIG. 2B, the open / close valve 14 is closed, and the measuring chamber 11 is sealed. Thereafter, the discharge piston 22 is raised, and the opening 25 of the first passage 21 is opened. Since the opening / closing valve 14 is already closed when the opening 25 is opened, the pressure in the third passage 5 does not act on the measuring chamber 11 and the second passage 19, and from the opening 25 to the first passage 21. The liquid L hardly flows in. By opening the opening 25, the flow path is connected from the measuring chamber 11 to the discharge nozzle 26.

Next, as shown in FIG. 2C, the extrusion piston 15 is lowered by an amount corresponding to the single discharge amount of the liquid L. At this time, if the liquid L is lowered at a low speed that is not affected by the compressibility of the liquid L, the volume corresponding to the piston stroke is pushed out as it is, so that the target discharge amount can be controlled with high accuracy. As the extrusion piston 15 is lowered, the liquid in the measuring chamber 11 is introduced into the first passage 21 through the second passage 19 and the opening 25. FIG. 2C shows an example in which the liquid L is not discharged from the discharge nozzle 26 when the extrusion piston 15 is moved forward by one time. However, the discharge amount per time is larger than the volume of the first passage 21. Even in this case, a part of the liquid L is ejected from the ejection nozzle 26, but the target ejection amount can be controlled with high accuracy.

Next, as shown in FIG. 2D, the ultrasonic transducer 23 is operated, the amplitude is amplified by the discharge head 20 and transmitted to the discharge nozzle 26, and at the same time, the discharge piston 22 is lowered, and the first passage 21. The entire amount of the liquid inside is discharged from the discharge nozzle 26. When the discharge piston 22 descends, the opening 25 is immediately closed, so that the liquid in the first passage 21 and the liquid in the second passage 19 are separated. Since the discharge piston 22 serves as a valve that prevents the liquid from flowing into the measuring chamber 11, only the liquid in the first passage 21 is discharged. Further, the effect of ultrasonic vibration prevents the liquid from remaining on the tip and side surfaces of the discharge nozzle 26 and the stringing phenomenon of the liquid, and a certain amount of the liquid L is reliably applied to the application object W.

When one discharge is completed, the application object W is moved or the quantitative application device is moved to another position, and the operation of (c) to (d) in FIG. Is repeated until the liquid in the measuring chamber 11 is exhausted. After the extrusion piston 15 reaches the bottom dead center, the state returns to the state of FIG. 2A again, and thereafter the same operation is repeated.

The fixed amount dispensing apparatus according to the present invention is not limited to the above-described embodiment.
In the above embodiment, the syringe 1 is provided on the upstream side of the measuring chamber (accommodating chamber) 11, and when the push piston 15 reaches the bottom dead center (when the measuring chamber is emptied), the liquid is supplied from the syringe 1. However, the measuring chamber 11 may be a single-use sealed structure such as a syringe, and the upstream syringe 1 may be omitted.
Moreover, although the example which provided the 2nd channel | path 19 in the connection member 18 which connects the discharge head 20 and the measurement chamber main body 10 was shown, you may comprise a 2nd channel | path with a resin flexible hose or a metal pipe. You can also. In particular, in the case of a flexible hose, a vibration suppressing effect that suppresses propagation of ultrasonic vibration to the storage chamber 11 is high.
The liquid used in the present invention is not limited to liquids at room temperature such as conductive adhesives, sealing resins, insulating adhesives, solder pastes, silicone oils, and ceramic slurries, but is solid at room temperature. Alternatively, it may be liquid (for example, wax) that becomes liquid upon heating.

It is a block diagram of an example of the fixed-quantity discharge apparatus concerning this invention. It is operation | movement explanatory drawing of the fixed quantity discharge apparatus of this invention. It is sectional drawing of an example of the conventional fixed volume discharge apparatus. It is a fragmentary sectional view of the other example of the conventional quantitative discharge apparatus.

Explanation of symbols

A storage part B measuring part C discharge part L liquid 1 liquid storage container (syringe)
3 Pressurizing means 5 Third passage 11 Weighing chamber (accommodating chamber)
12 Inlet 13 Discharge 14 Open / close valve (open / close means)
15 Extrusion piston 17 Voice coil motor (drive means)
18 connecting member 19 second passage 20 discharge head 21 first passage 22 discharge piston 23 ultrasonic transducer 24 air cylinder (driving means)
25 Opening 26 Discharge nozzle

Claims (5)

A storage chamber for storing a liquid and having a discharge port for the liquid;
An extruding piston that slidably reciprocates in the storage chamber, and extrudes the liquid stored in the storage chamber by a predetermined amount from the discharge port;
A first passage having a discharge nozzle for discharging liquid at one end and an opening on a side surface;
A second passage connecting the opening of the first passage and the outlet of the storage chamber;
A discharge that slidably reciprocates in the first passage, opens the opening in the retracted position, closes the opening in the forward position, and discharges the entire amount of the liquid in the first passage from the discharge nozzle. A piston,
Drive means for reciprocating the discharge piston;
An apparatus for quantitatively dispensing liquid, comprising: an ultrasonic wave application unit that applies ultrasonic vibration to the discharge nozzle to improve the separation of the liquid from the discharge nozzle. Between the member constituting the second passage and the member constituting the first passage, an elastic body that suppresses propagation of ultrasonic vibration generated by the ultrasonic application means to the storage chamber is formed. 2. The liquid dispensing apparatus according to claim 1, further comprising vibration suppressing means. The member constituting the second passage is formed of a soft material that suppresses propagation of ultrasonic vibration generated by the ultrasonic wave application means to the storage chamber. Liquid dispensing device. A liquid storage container for storing the liquid is provided;
Pressurizing means for applying a predetermined pressure to the liquid in the liquid storage container and pushing it out is provided,
A third passage is provided for guiding the liquid pushed out of the liquid storage container by the pressurizing means to the storage chamber;
To push the liquid in the storage chamber each time the extruding piston is advanced by one step from a predetermined amount by the discharge port, the controllable drive means is provided a moving amount of the extrusion piston,
The liquid according to any one of claims 1 to 3, wherein an opening / closing means that is opened only when the liquid is replenished from the liquid storage container to the storage chamber is provided in the middle of the third passage. Constant discharge device. The liquid dispensing apparatus according to claim 4 , wherein the driving means for driving the extrusion piston is a voice coil motor.

Images