JP2008036459A - Apparatus for supplying powdered paint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus which enables a further stable supply as a positive displacement pump enabling a fixed quantity supply for a powder supply, and can control easily the supply rate as required, and to improve a workability in changing powdered paints since cleaning of the supply apparatus is easy in case of using particularly various kinds of and many colors of the powdered paints. <P>SOLUTION: In the positive displacement powder pump carrying out a suction and discharge by changes in pressure reduction and pressurization of the internal volume, inlet and outlet paths of the powder are connected to a pump chamber controlled by a moving body and maintaining a quantitative volume, and a pumping passage and an air intake passage communicated with the pump chamber are connected to the moving body through a filter portion. The circulation is controlled by valve means opening and closing alternately respectively, the pumping passage is closed when the outlet path is closed, and the air intake passage is closed when the inlet path is closed. Thus, the opening and closing control is carried out. The moving body moves in the chamber using an advancing and retracting means such as a screw member and can change and regulate optionally the internal volume. Further, a cleaning airflow port is provided on the pumping passage to aim a simplification of the cleaning. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a quantitative supply device for supplying powder paint in a powder coating to a coating gun, and more particularly to a device for stably supplying powder quantitatively set by a cylinder-type pump.

Compared to coating with a liquid paint that uses a solvent and forms a coating film by drying, powder coating does not use a solvent, so it can save resources and prevent the discharge of volatile organic compounds. There are advantages such as excellent strength. Furthermore, it is known as a coating method that can easily collect and reuse a paint that has not been applied to an object to be coated, and is excellent in effective use of resources.

In powder coating, there are several methods for attaching or applying a paint to an object to be coated. Of various powder coating methods, the powder paint is sprayed with a spray gun and the object is coated by electrostatic force. The method of fusing by heating after adhering to the coating is a versatile coating method that can handle a wide range of objects to be coated, and is widely applicable in many fields compared to other powder coating methods. ing. In this case, a powder supply device for supplying powder in a fluidized state together with compressed air and an electrostatic powder spray gun that is generally used as a spray gun for spraying toward the object to be coated function. The effect can be achieved by being used in combination.

The stable supply of powder has a great influence on the quality of the coating film in the end, and is an important issue not only for improving the quality but also for improving the productivity. Many proposals for improvement have been made so far. In general, a pump used for supplying powder is an injector pump that uses a negative pressure associated with the flow of compressed air and sucks it together with the compressed air, or a cylinder pump that uses a reciprocating piston.

In the case of the injector method, the supply amount depends on the pressure of the compressed air that generates the suction force, and also depends on the resistance of the supply path, etc., making it difficult to stably supply the fixed amount. Therefore, complicated control such as adjusting the compressed air by using feedback or using an adjusting valve is required. This injector system is characterized by a large amount of compressed air when it is supplied. Especially in powder coating, compressed air is ejected more than necessary when spraying on the object to be coated, and the coating quality and coating performance are adversely affected. There was a problem of giving.

On the other hand, the cylinder system is a positive displacement pump, which is superior to other systems in terms of quantitativeness, and has a feature that stable supply is possible. In addition, the compressed air for transport is extremely small compared to the above-mentioned injector system, and there are advantages such as the ability to supply a wide range of stable powder from small to large quantities. It has been evaluated as a powder coating supply device that can cope with various coating conditions.

However, even in the positive displacement type, the cylinder type having the configuration of FIG. 3 that operates the piston has an operation part P that slides inside, and the powder is slid by this or enters into the gap and is damaged. As a result, the properties of the powder coating material may be changed to impair the life of the powder coating material and cause damage to the pump itself. For this reason, a technique has been proposed in which a measuring chamber having a constant volume is provided, powder is sucked into the measuring chamber by a suction pump or the like, and the powder is repeatedly supplied by a discharge method using pressurized air.

As an example of this, Japanese Patent Laid-Open No. 2001-199544 can be cited, but in the case of the technology of the present invention, the measuring chamber has a constant volume, and the amount of powder supplied is determined by the number of operations per hour, Although it can be applied, fine adjustment is difficult in powder coating in which it is necessary to control the powder supply amount in response to the coating conditions, and there is still room for improvement. In other words, since the number of operations per hour includes the time condition for introducing into the measurement chamber by suction and the condition for discharging and supplying, the operation time per hour can be adjusted by simply adjusting the operation time of each control valve. The correct supply cannot be obtained. In addition, since the filter connected to the weighing chamber is provided in the passage, the flow area is not large, and therefore the frequency of cleaning is increased, and the maintenance itself takes time. There are still problems to be solved.
JP 2001-199544 A

Quantitative stability of powder supply in powder coating is an important issue for improving coating quality and increasing industrial productivity, and several developments have been made so far. There are basically several methods of supply, but as a recent supply method that emphasizes stable supply, a positive displacement pump that discharges aspirated powder into a room with a constant volume controls spraying. Utilization is increasing from the nature.

Among them, the suction method to the fixed volume chamber by the air flow and the discharge method by the pressurized air can be highly evaluated for the stabilization of the supply amount required for powder coating. Although it is suitable for simple supply, there are places where it is not enough to enable easy adjustment of the supply amount according to changes in conditions, such as powder coating.

An object of the present invention is to use a positive displacement pump capable of stable and quantitative supply for powder supply, to enable even more stable supply of the supply amount, and to easily adjust the supply amount as necessary. A supply device is provided.
In addition, when this type of supply device is used for a wide variety of powder paints, it is easy to clean the supply device, and the industrial productivity of powder coating as a supply device that enables efficient paint replacement. It aims to improve and produce economic and resource effects.

The present invention relates to a powder pump device that sucks and discharges by depressurization and pressurization, wherein a part of the wall of the pump chamber is constituted by a moving body, and the powder is adjusted in the pump chamber that is adjusted by the moving body to maintain a fixed volume. An inlet passage and an outlet passage of the body are connected, and the moving body connects an intake passage and a pressure feed passage that lead to the pump chamber through a filter portion. The inlet passage, the outlet passage, and the intake passage and the pressure feed passage are controlled to flow by valve means that open and close alternately, the pressure feed passage is closed when the outlet passage is closed, and the intake passage when the inlet passage is closed. Is controlled to open and close.

The moving body is configured to be able to move and move inside the room using an advancing / retreating means such as a screw member and arbitrarily change and adjust the internal volume.
Further, the moving body is constituted by an air chamber in which a porous plate is disposed on the chamber side and the opposite side is connected to the pressure-feed passage and the intake passage. Further, a plurality of pump bodies are provided side by side, and a phase difference is provided in the valve operation of each pump so that the pumps are sequentially and repeatedly discharged and continuously supplied.

The valve means for opening and closing the inlet passage and the outlet passage uses a pinch valve.
A cleaning airflow port is provided between the pressure feed passage and the air chamber to connect to a compressed air supply source, a discharge port is provided in the pump chamber, fresh air is sent to the filter through the air chamber, and excess air is Exhaust from the outlet.

In the pump of the present invention, the pump chamber in which powder is repeatedly flown in and out during operation is adjusted by the moving body to maintain a constant volume, and there is no sliding part, so that the operation is unstable and the powder paint There is no damage or alteration, the life of the powder coating can be maintained for a long time, and a stable supply can be continued. The moving body partitions the pump chamber by a filter and variably adjusts the volume thereof, and is connected to the intake passage and the pressure feed passage. Therefore, the pump volume is set as necessary, and the volume is maintained constant. Stable supply is possible by repeating continuous operation.

The pump chamber configuration itself is a simple configuration with no moving parts during operation, so it is easy to reduce the size of the device itself. In addition, a highly accurate supply over a wide supply range as a device combining multiple pump chambers. A device can be configured.

The movable body makes the effective internal volume of the pump chamber variable, and is configured to advance and retreat using means such as screws, and its position can be easily adjusted from the outside, so depending on the coating conditions of powder coating It is possible to set and appropriately set the supply amount according to the required conditions. As a result, it is possible to improve and maintain the coating quality and to efficiently use the paint.

As described above, the pump chamber according to the present invention has a simple structure, and the flow path as an internal action has a simple shape, so that accumulation and adhesion of powder paint are prevented. Since the cleaning airflow port through which fresh air flows is provided, the powder adhering to the filter can be wiped off and dropped into the pump chamber, and the filter can be easily cleaned to maintain a stable function. The discharge port provided in the pump chamber has the function of expelling the cleaning air introduced separately from the powder supply when cleaning, and facilitates color change etc. periodically. be able to.

In the embodiment of the present invention, a single pump 1 shown schematically in FIG. 1 is used as a single element, and a plurality of these are practically used as a supply device. A single pump 1 sucks and discharges powder, and a cylinder 2 serving as a container for discharging and discharging forms a pump chamber 3 and has a bottom 31 that is easy to flow downward, followed by a powder inlet 4 and an outlet 5 respectively. The powder inlet 4 is connected to the powder container 6, and the powder outlet 5 is connected to the spray spray gun 7 via passage opening / closing means 10 and 11, respectively.

Here, the passage opening and closing means 10 and 11 control the flow of the powder by blocking or opening the powder flow conduit 13. As suitable for this kind of control, the passage is closed and the cross section of the passage is closed. A pinch valve type is applied. In this case, there is no level difference in the cross section of the passage, and local operations such as cleaning can be easily performed without causing local accumulation of powder.

A moving body 12 is fitted to the upper portion of the pump chamber 3 so as to be moved up and down in a confidential state by a sealing material. In the embodiment, packings 15 that are kept secret from the inner wall 32 of the pump chamber 3 and can be moved up and down are provided on the outer periphery of the moving body 12 at the upper and lower portions. The seal material itself is not particularly new and can be used for O-rings that have been known so far, so as to maintain stability by arranging it vertically as shown in the figure depending on the size and width of the moving body. It is also necessary to consider.

The structure of the moving body 12 is provided with a porous filter 16 on the pump chamber 3 side to partition the upper air chamber 33 so that the powder in the pump chamber 3 does not flow into the air chamber 33 side. As the filter 16 itself, a filter having a pore size of several micrometers or less is often used so as to block fine particles contained in the powder. These are selected according to the properties of the powder used, and are not limited in a fixed manner.

In the air chamber 33 of the moving body 12, pressurized air is supplied to the pump chamber 3 through the filter 16 and the internal powder is discharged from the outlet 5 and supplied to the spray spray gun 7. In addition, an intake passage 18 for sucking powder into the pump chamber 3 from the inlet 4 with the pump chamber 3 set to a negative pressure is connected.

The moving body 12 itself is provided with an adjusting shaft 20 for adjusting the position by sliding the inner wall 32 of the pump chamber 3 up and down, a lid 21 which is substantially isolated and fixed in the pump chamber, and a screw portion. The relative position can be changed by 22. There are several possible configurations for changing the position of the movable body 12 by moving the movable body 12 up and down by the rotation of the adjustment shaft 20, but here the adjustment shaft 20 that idles from the movable body 12 is considered. It is configured to move up and down together with the moving body 12 by being screwed into the threaded portion of the lid 21 and rotating the knob 23 on the head.

The moving body 12 can change the volume in the pump chamber 3 by its vertical movement, and can change the powder supply amount per one time by suction and discharge. The pressure feeding passage 17 and the intake passage 18 of the moving body are connected to a pressurized air source and an intake means through a control valve 25, respectively. The intake means is means for sucking the atmosphere to obtain a negative pressure state, and is generally connected to the suction side of a blower or a vacuum pump.

The passage opening and closing means 10 and 11 and the control valve 25 provided in the pressure feeding passage 17 and the intake passage 18 and the inlet passage 13 and the outlet passage 14 are controlled to open and close in order to smoothly supply powder. That is, when the pinch valve 10 of the inlet passage is open, the outlet passage 11 is closed, the pressure feeding passage 17 is shut off and the intake passage 18 is opened, so that the intake means makes the internal pressure of the pump chamber 3 negative and the powder paint Is sucked into the pump chamber 3. The sucked powder is spray-sprayed from the outlet passage 5 through the passage opening / closing means 11 by the pressurized air fed from the pressure feeding passage 17 through the control valve 25 (B) by switching each valve operation. It will be supplied to the gun 7.

The passage opening / closing means 10 and 11 and the control valve 25 provided here are individually formed and controlled to be opened and closed by the control device 29. However, the control valve structure is an integrated configuration. A switching valve structure may be adopted, and an existing control valve structure can be adopted according to the configuration and specifications of the apparatus.

The powder supplied here is sucked into the pump chamber 3 from the powder container 6 while being fluidized by a small amount of air, and is supplied by pressurized air. When the conditions of intake and pressurization are not changed, the powder supply amount per one time maintains a fixed amount, and the capacity of the pump chamber 3 specifies the supply amount. As can be understood from the principle of operation, in the case of such a pump, supply is intermittent because suction and discharge are repeated. Therefore, normally, at least a plurality of pumps are provided together so that suction and discharge are alternately repeated.

The example of FIG. 2 shows an example in which three pump units 1 are operated with the same phase difference and used as one set of pumps, and four further examples are connected. In this case, although not shown, the timing of opening and closing the control valves and passage opening / closing means (pinch valves) of each of the three pumps is controlled based on the above operation. Depending on the number of spray spray guns to be supplied and the supply amount, a plurality of pump sets may be prepared, and the supply of each may be controlled.

Further features of the present invention are described below. Each pump chamber 3 is provided with an exhaust port 26 different from the outlet passage 11. The exhaust port 26 is preferably provided at a position above the pump chamber and not closed by the lowermost position of the movable body in the previous period. The exhaust port 26 is used not when the normal supply operation is performed but when the operation is interrupted and the inside of the pump chamber 3 is cleaned when the powder coating material supply system is cleaned or when the color / paint is changed. That is, if the use time is prolonged, the filter 16 such as the porous plate of the moving body 12 is clogged, and it is difficult to supply and transport an appropriate powder. Therefore, periodic cleaning is a necessary condition, and it is required to reliably clean in a short time.

For cleaning, after stopping the flow of powder, a cleaning air flow port 27 is connected to the pressure feed passage 17, compressed air is blown from the filter 16 into the paint pump chamber 3, and the powder deposited and deposited on the filter 16 is blown off. Is done by. At this time, excess gas and powder can be discharged from the exhaust port 26 of the pump chamber 3 and / or from the outlet passage 11. Generally, a large amount of air is required for cleaning, and at this time, the exhaust port 26 works effectively. In addition, it is possible to introduce from the pressure feed passage 17 at the time of cleaning, but considering the complicated setting change and adjustment of the control valve, the cleaning air controlled by the valve 28 by another circuit is sent from the cleaning air flow port 27 to the pressure feed passage. 17 is preferably introduced.

It is a structure explanatory view of a pump room showing the outline of the present invention. FIG. 3 is a configuration diagram when the pump used in one embodiment of the present invention is provided and used as a stable supply device. It is a section schematic diagram showing an example of the conventional piston type positive displacement feed pump structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pump single unit 3 Pump chamber 4 Inlet 5 Outlet 7 Spray spray guns 10 and 11 Passage opening and closing means 12 Moving body 16 Filter 17 Pressure feed passage 18 Intake passage 20 Adjustment shaft 21 Lid 22 Screw part 23 Knob 25 Control valve 26 Exhaust port 27 Cleaning airflow mouth

Claims (6)

In the supply device for powder that sucks and discharges the pressure in the fixed volume by reducing the pressure in the intake air, sucks the powder, and discharges it by introducing compressed air, the fixed volume is adjusted by the moving body that forms part of the inner wall A powder chamber is connected to an inlet passage and an outlet passage of the powder, the moving body is provided with a filter portion, and an intake passage and a pressure feed passage are connected to the pump chamber through the filter portion. The flow of the passage and the outlet passage and the intake passage and the pressure feeding passage are controlled by valve means that open and close alternately, the pressure feeding passage is closed when the outlet passage is closed, and the intake passage is closed when the inlet passage is closed. A device for supplying powder paint that is controlled to open and close. 2. The powder coating material supply apparatus according to claim 1, wherein the movable body is configured to move in the pump chamber using advancing and retracting means such as a screw member, and to arbitrarily change and adjust the pump chamber volume. 2. The powder coating material supply apparatus according to claim 1, wherein the movable body includes a porous plate disposed on the pump chamber side, and an air chamber in which a pressure-feed passage and an intake passage are connected on the opposite side. 2. The powder coating material supply apparatus according to claim 1, wherein a plurality of pump chambers are provided, and the operation of the valve means in each pump chamber is provided with a phase difference, repeatedly discharged sequentially, and continuously supplied. 4. The powder coating material supply device according to claim 1, wherein the valve means for opening and closing the inlet passage and the outlet passage is a pinch valve. 4. The apparatus for supplying powder coating material according to claim 1, wherein a cleaning airflow port is provided in the pressure feed passage and connected to a supply source of compressed air, and a discharge port is provided in the pump chamber.

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