JP5270909B2 - Cylinder pump device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve stability in quality of coating to enable spraying under the same conditions by preventing fluctuation in an initial discharge of supply coating by a cylinder pump. <P>SOLUTION: In the cylinder pump, a stroke of the pump is controlled by a servomotor, the filling side is connected to the supply means via. the switching valve, and the discharge side is connected to a spray gun via. a supply hose. The discharge side of the cylinder pump is provided with a pressure sensor, the servomotor is driven by a control means according to the output of the pressure sensor, and the pressure inside the supply passage before starting spraying is adjusted at the pressure at normal continuous discharge. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

The present invention relates to a cylinder pump device that improves the accuracy of supply of a paint to a spray gun and stabilizes it in spray coating, and particularly relates to a technique that is applied to a region of a low supply amount with a low-viscosity paint.

In the field of spray coating, high-function, high-quality thin-film coating is required for the coating of electronic equipment and precision equipment typified by mobile phones and digital cameras, and it is important to stably supply a small amount of paint with high accuracy. ing. Many of these are represented by plastic coating, and a stable supply of trace amounts is an indispensable prerequisite.
In addition, for multi-component reaction type paints, there is an increasing demand for a stable supply of a small amount of paint, as the accuracy of the mixing ratio is an absolute requirement for ensuring the quality of the coating film.

On the other hand, in the supply of paints, with water-based paints with thixotropy, the viscosity of the paint changes due to the stirring state, and generally the fluidity varies depending on the viscosity change due to the environmental temperature. Instability is a problem. For this reason, in order to prevent the occurrence of defective products and maintain the coating quality, the result is that the operator and the production manager are burdened with frequent monitoring and adjustment of the discharge amount for coating management.

In such a situation, many improvements have been proposed, and one of them is quantitative discharge by a positive displacement pump. Of these, gear pumps are used as typical ones, and positive displacement gear pumps are more stable than pressure type pumps. However, they are used when considering internal fixation in UV paints and reactive multi-liquid paints. It is difficult, and the theoretical discharge amount and the actual discharge amount do not match exactly due to the paint leak in the gear, and this depends on the type and conditions of the paint used. However, it is not always sufficient in terms of industrial productivity.

In addition, a paint supply apparatus using a cylinder pump composed of a cylinder and a piston as a positive displacement pump has been proposed. This is due to the configuration of the syringe pump described in Japanese Patent Application Laid-Open No. 2002-159907 and Japanese Patent Application Laid-Open No. 2002-361124, and enables the discharge of a volume corresponding to the stroke by a piston reciprocated in the cylinder. Is. The piston is controlled by the drive of a servo motor to perform accurate discharge.

However, even in this case, the amount of paint discharged from the spray gun is unstable due to the pressure of the paint filled in the cylinder. There are problems such as being unable to use.

That is, in the case of this type of pump, the paint is filled into the cylinder while the cylinder is pulled and the paint is fed into the cylinder by another paint supply means. At this time, the spray gun connected to the inside of the cylinder and connected via the supply pipe line is closed, and at the time of filling, it is performed while balancing the increased volume in the cylinder during the pulling operation and the amount of filling liquid, and the stop is also synchronized. Has been. However, the pressure in the spray gun supply path at the end of filling is not always stable due to subtle timing differences and filling side pressure.

During discharge, the pressure in the supply path is usually connected by a resin paint hose, and the accumulated paint in the expanded hose is discharged at a pressure higher than a predetermined pressure until it stabilizes. In the initial stage of spraying, a discharge amount more than usual is ejected. Conversely, when filling from the supply means is stopped in a state where the pressure in the supply path does not reach the predetermined pressure, the initial discharge is small and it takes time to reach the predetermined amount.

In automatic painting, especially robot painting, a slight loss time reduces productivity, so it is necessary to be able to paint immediately under normal conditions. Therefore, it is required to reduce the wasted time at the initial stage of spray coating as much as possible. Furthermore, spraying with an inappropriate discharge amount at the initial stage of spraying cannot be used for actual coating, and wasteful paint is wasted as throwing away, which is not preferable in terms of economy and resources.

As described above, the paint filling to the cylinder pump is performed by keeping the balance between the pump filling operation and the supply operation on the supply side in a balanced manner. do not do. For this reason, the pressure in the supply path on the gun side changes, the spraying conditions at the beginning of spraying change, and the coating quality varies.

The object of the present invention is to take advantage of the characteristics of a cylinder pump capable of discharging at a constant volume, and to adjust the pressure fluctuation in the paint supply path caused by a subtle timing shift in operation, etc., thereby preventing fluctuations in initial discharge. Therefore, spraying is possible under the same conditions.

The stroke of the cylinder pump is controlled by a servo motor, the cylinder pump filling side is connected to the paint supply means via the switching valve, and the discharge side of the cylinder pump connected to the spray gun via the supply hose. Servo that adjusts the internal pressure of the supply path by changing the internal volume of the cylinder pump according to the difference between the pressure detected by the pressure sensor at the end of paint filling and the continuous discharge pressure during normal painting A control device for outputting a control signal for driving the motor is provided.

When the discharge side pressure is higher than the continuous discharge pressure during normal painting , the servo motor is driven in the direction of expanding the stroke volume of the cylinder pump, and when the discharge side pressure is lower than the continuous discharge pressure during normal painting, Then, the servo motor is driven in the direction of reducing the stroke volume of the cylinder pump to bring the filling pressure closer to the continuous discharge pressure. The servomotor takes the tuning and detecting the pressure in the discharge side, the row Nau drive that matches the predetermined pressure.

According to the above configuration, the paint filled in the cylinder pump is caused by a slight timing shift between the drive control of the paint supply means to be filled and the servo motor drive on the cylinder pump side, the difference in conditions at the time of paint supply, etc. Even if there is a fluctuation in the filling pressure, the cylinder volume is adjusted and driven according to the result of immediate pressure detection, the pressure at the start of spraying of the spray gun can be kept constant, It is possible to keep the coating quality constant as it is the same as continuous and out.

In addition, it can be applied to the actual object to be coated from the beginning of spraying, can eliminate coating time loss and waste of paint due to throwing away, and can improve productivity, resource efficiency, and other economics.

Details of the embodiment of the present invention will be described with reference to the schematic configuration diagram of FIG. The cylinder pump 1 is a pump having a structure in which the stroke internal volume of the cylinder 11 is changed by a piston 12 provided in the cylinder 11 and reciprocating, and the filled paint is sent out by repeating filling and discharging. The piston 12 is reciprocated by a connecting rod 14 fixed to a rod 13, and the connecting rod 14 is reciprocated by being screwed with a screw 17 screwed on a rotating shaft 16 rotated by a servo motor 15. It has a configuration. A detailed configuration such as ensuring the airtightness of the cylinder pump 1 is known as an existing technology, and is omitted here.

The discharge side of the cylinder pump 1 is connected to a spray gun 4 via a supply line 3. Usually, the spray gun is mostly moved during painting, and the supply line 3 is mostly formed of a flexible resin paint hose. The spray gun 4 is generally called an automatic spray gun, and its operation is controlled by air or the like, and has a configuration in which a paint valve provided at the tip is controlled to open and close from the outside.
In the configuration according to the present invention, a pressure sensor 5 is provided in the discharge side supply pipe 3, and the pressure in the pipe is detected and output to the control device 6.

On the other hand, another paint supply means 8 is connected to the inlet side of the cylinder pump 1 via a switching valve 7, and the switching valve 7 is operated by a signal from the control device 6 so that the paint supply means 8 supplies the cylinder pump 1 to the cylinder pump 1. In this configuration, paint is fed. The paint supply means 8 is not particularly limited as long as it supplies the paint by pressure supply, and a known paint pump is used. The cylinder pump 1 is filled by the command of the control device 6 so that the servo motor 15 rotates in the direction of lowering the piston and the stroke volume in the cylinder 11 is increased. At the same time, the switching valve 7 is opened and the paint is fed and filled. . This series of operations is performed in synchronization with the control device when the spray gun 4 is operated, that is, when spraying is stopped.

During spray coating, the servo motor 15 is driven simultaneously with the paint valve opening of the spray gun 4, and the paint is pushed out while being controlled at a stable appropriate amount and discharged from the spray gun 4. At the same time, the controller 6 is synchronized so that the servo motor 15 stops. In this embodiment, the amount that can be controlled and discharged by the pulse signal from the servomotor is 0.001 ml per pulse, and high accuracy can be maintained.

In the present invention, in the operation of the cylinder pump 1 configured as described above, the pressure in the supply pipe line after filling is detected by the pressure sensor 5, and the detected value is higher than the reference value when continuous discharge is performed in normal coating. In this case, the servo motor 15 is driven in a direction to increase the stroke internal volume of the cylinder 11, and a signal is sent from the control device 6 so that the pressure becomes the reference value.

That is, in general, the supply pressure from the coating material supply means is higher than the pressure at the time of discharge and the filling is performed quickly, so that the pressure in the supply line is also high at the end of the filling (when stopped). Therefore, as described above, the discharge pressure at the initial stage of spraying is high and the discharge amount increases. The internal pressure of the supply line is composed of a flexible resin paint hose. The higher the pressure, the higher the internal volume. By expanding the internal stroke volume of the cylinder, the accumulated pressure is absorbed, The pressure value can be adjusted.

If the detected pressure after filling is lower than the reference pressure due to another cause, the piston 12 is pushed up so that the pressure corresponding to the difference from the detected value increases, and the internal volume of the stroke is reduced. The pressure rises. In any case, the control device is programmed to move the position of the piston 12 in a direction approaching the set pressure.

2 to 4 show respective pressures when the pressure (residual pressure) applied to the spray gun 4 on the discharge side of the cylinder pump 1 is higher than the normal continuous discharge pressure, when it is low, and when adjusted according to the present invention. And a graph showing the fluctuation state of the discharge amount over time. In FIG. 2, when the discharge flow rate is set to 120 ml / min, if the residual pressure is approximately equal to the supply pump pressure as the paint supply means, spraying is started and 0.5% is maintained until the discharge amount stabilizes at the set value.
Nearly sec, it takes about twice as long as when spraying is started from the adjusted residual pressure in FIG.

In the meantime, in the case of FIG. 2, the initial ejection amount is twice the set value, and painting on the object to be painted is impossible. I can't start. Further, as shown in FIG. 3, in the test in which the residual pressure at the initial stage of spraying is set low (in this case, zero), it takes time to rise and further time is required to stabilize. Therefore, in this case as well, lost time and waste of paint discharge are eliminated, stable spraying cannot be performed quickly, and high-quality and high-quality coating cannot be performed.

The pressure for adjusting the filling pressure in the cylinder varies depending on various conditions sprayed by the spray gun, and these are confirmed in advance in the test. That is, the amount of spraying varies depending on the coating / painting conditions, and a standard discharge amount serving as a reference is determined, whereby the discharge pressure related to the specifications of the spray gun to be used is set. These set values are input to the control device and output as respective control signals.

As described above, the present invention uses an automatic spray gun equipped with a paint valve, performs painting quickly on an object to be painted by a painting robot, etc. A very effective supply device can be obtained when a coating apparatus is required. In addition, it is possible to bring about a great effect in the field of automatic painting, such as eliminating the need for abandonment at the beginning of spraying, reducing waste of paint and improving economy.

1 is a schematic diagram illustrating a configuration of the present invention. The graph which shows the change state of the discharge pressure and flow volume at the time of spraying in the state where the residual pressure in a cylinder pump is high. The graph which shows the change state of the discharge pressure and flow volume at the time of spraying in the state where the residual pressure in a cylinder pump is low. The graph which shows the change state of the discharge pressure and flow volume at the time of spraying in the state which adjusted the residual pressure in a cylinder pump.

Explanation of symbols

1. Cylinder pump 3, supply line 4, spray gun 5, pressure sensor 6, control device 7, switching valve 8, paint supply means 11, cylinder 12, piston 13, rod 14, connecting rod 15, servo motor 16, rotation Shaft 17, screw

Claims (2)

The stroke of the cylinder pump is controlled by a servo motor, the cylinder pump filling side is connected to the supply means via a switching valve, and the discharge side is a cylinder connected to a spray gun equipped with a paint valve via a supply hose A pressure sensor is provided on the discharge side of the pump and the cylinder pump, and the stroke volume of the cylinder pump is changed according to the difference between the detected pressure of the pressure sensor at the end of paint filling and the continuous discharge pressure at the time of normal painting A cylinder pump device comprising a control device for outputting a control signal for driving a servo motor for adjusting an internal pressure. When the discharge side pressure is higher than the continuous discharge pressure during normal painting , the servo motor is driven in the direction of expanding the stroke volume of the cylinder pump, and when the discharge side pressure is lower than the continuous discharge pressure during normal painting, The cylinder pump device according to claim 1, wherein the servo motor is driven in a direction to reduce the stroke volume of the cylinder pump.

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