JP5487773B2 - Method and apparatus for controlling spray amount of coating apparatus - Google Patents

Description

  The present invention relates to an injection amount control method and apparatus for a coating apparatus that can accurately adjust the spray amount of paint sprayed by a spray gun.

  For example, when painting to form a heat-resistant coating film on the shaft, a paint film mixed with metal powder such as aluminum is sprayed onto the shaft to form a paint film, and then baked to form the paint film. It is integrated with the shaft. This type of paint includes water-based and solvent-based ones in which metal powder is mixed in various solvents depending on the purpose. For example, there are high-concentration paints containing several tens of percent of metal powder by weight.

  When painting a shaft using a paint mixed with metal powder as described above, a thin and uniform coating film should be formed so that the coating film does not cause problems such as cracks during baking after painting. Is strictly demanded.

  However, the coating material in which metal powder is mixed has a problem that the powder is likely to precipitate and separate, and therefore clogging is likely to occur. Further, particularly in the case of water-based paints, dripping tends to occur when applied, and for this purpose, it is necessary to form a thin coating film by spraying little by little. For this reason, when coating the shaft, after coating and drying so as to have a thin and uniform thickness of about 10 μm or less, this coating and drying operation is repeated, for example, 6 to 7 times. As a result, a coating film of about 50 to 60 μm is formed.

  As described above, in order to uniformly form a coating film having a thin thickness of about 10 μm or less, a coating apparatus that can stably spray a very small flow rate of paint is required.

  As a coating apparatus for coating using a paint in which powder is mixed in a solvent, a powder is prevented from being precipitated by circulatingly supplying the paint (Patent Document 1), or a powder and a solvent are used. There is one that is mixed immediately before injection (Patent Document 2). In addition, when circulating the paint to be supplied to the spray gun, there is a system in which the flow rate of the paint to the spray gun is adjusted by providing a bypass path and reducing the flow rate of the bypass path (Patent Document 3). .

  However, since all of the above Patent Documents 1 to 3 supply the paint to the spray gun by the supply pump, it is inevitable that the supply of paint pulsates. It is difficult to discharge stably from a spray gun.

  On the other hand, FIG. 3 shows an example of an initial coating apparatus implemented by the present inventors, and the pressure supply air 3 from the pressure supply air supply apparatus 2 is supplied to the paint supply tank 1 charged with the paint a. It is supplied via a supply-side pressure setting device 4 such as an electropneumatic regulator, and the paint a in the paint supply tank 1 is supplied to the spray gun 5 via the supply pipe 6 by the pressure of the air 3 for pressure feeding. Part of the paint a supplied to the spray gun 5 is discharged to the spray gun 5 by an opening / closing means 15 such as a needle valve provided in the spray gun 5, and the discharged paint is supplied from the atomizing air supply device 13. It is atomized by the atomizing air 14 and sprayed from the tip 5 a of the spray gun 5. On the other hand, the remaining paint a ′ that has not been discharged to the spray gun 5 is collected in the paint collection tank 8 by the return pipe 7. The upper part of the paint recovery tank 8 is opened to the atmosphere through an opening 9.

  The paint powder is precipitated in the paint supply tank 1 and the paint recovery tank 8 by stirring the paint a by the stirring air 12 from the stirring air supply device 11 or by being electrically rotated. A stirrer 10 is provided to prevent the above.

  As described above, Japanese Patent Application Laid-Open No. H10-228688 discloses a technique in which air for pressure feeding is supplied to a paint supply tank and paint is supplied to a spray gun by air pressure. Further, there is Patent Document 5 as a circulation type spray gun in which the circulation channel is passed to the inside of the spray gun.

  According to the apparatus shown in FIG. 3 and Patent Documents 4 and 5, the amount of paint sprayed from the spray gun can be stabilized as compared with Patent Documents 1 to 3.

JP 2004-330119 A JP 2003-033681 A Japanese Patent Laid-Open No. 06-047330 JP 2000-325837 A JP 2006-055736 A

  In the apparatus shown in FIG. 3 and Patent Documents 4 and 5, when the paint a in the paint supply tank 1 is supplied to the spray gun 5 by the air pressure of the pressure feeding air 3 and sprayed, the solid line is shown in FIG. In addition, when the pressure of the paint a at the supply pressure P1 (correlated with the paint circulation speed) in the paint supply tank 1 drops through the supply pipe 6 and the return pipe 7 and is recovered in the paint recovery tank 8. Atmospheric pressure P0. A part of the paint is discharged from the spray gun 5 at a relatively high discharge pressure P2 between the supply pressure P1 of the paint supply tank 1 and the atmospheric pressure P0. This discharge pressure P2 has a correlation with the discharge speed (flow rate) of the paint discharged from the spray gun 5. Here, in order to control the spray amount of the paint by the spray gun 5, it is necessary to accurately control the discharge pressure of the paint to the spray gun 5.

  Therefore, in order to discharge a small amount of paint from the spray gun 5, the supply pressure P1 of the paint supply tank 1 is set low as shown by the broken line A, and the discharge pressure P2 of the spray gun 5 is adjusted low. However, if the supply pressure P1 is adjusted to be low in this way, the flow rate of the paint discharge portion in the spray gun 5 becomes small, so that the discharge pressure of the paint in the spray gun 5 becomes unstable. That is, when the flow rate is reduced, the powder is easily separated, and the supply pressure P1 is low, so that the pressure is easily changed due to the flow resistance of the supply pipe 6 and the discharge of the paint becomes unstable. There is a problem that this phenomenon becomes more remarkable when discharging the ink.

  As described above, it is difficult to form a thin uniform coating film with high accuracy by spraying a small flow rate of paint from the spray gun 5 because stable discharge cannot be performed when a small flow rate of paint is discharged to the spray gun 5. Met.

  The present invention has been made in view of the above circumstances, and provides an injection amount control method and apparatus for a coating apparatus capable of stabilizing a flow rate of a paint discharged to a spray gun and accurately discharging a small flow of paint. It is something to try.

The present invention provides a paint supply tank that can be moved up and down, and adjusts the paint supply tank to a position higher than the spray gun so that the paint in the paint supply tank is supplied to the spray gun by gravity, and a part of the paint is supplied. Paint that is discharged from a spray gun and sprayed with atomizing air, and paint that is not discharged from the spray gun is collected in a collection tank by a collection pipe , and pressurized air is supplied to the paint supply tank to be supplied to the spray gun. The spraying amount control method of the coating apparatus is characterized by increasing the supply pressure of the coating apparatus.

  In the spray amount control method for the coating apparatus, when the height of the paint supply tank is changed variously, the discharge amount of the paint discharged from the spray gun is measured by the discharge amount detection device, so that the height of the paint supply tank is increased. The relationship between the position and the amount of paint discharged by the spray gun is obtained in advance, and the height is adjusted by raising and lowering the paint supply tank so that the target discharge amount by the spray gun is maintained based on the obtained relationship. Is preferred.

  In the spray amount control method of the coating apparatus, it is preferable that the paint in the paint recovery tank is returned to the paint supply tank and circulated for use.

The present invention comprises a paint supply tank for containing paint,
A spray gun connected to the paint supply tank via the paint supply pipe and discharging a part of the paint from the paint supply tank;
A tank lifting device that feeds the paint in the paint supply tank to the spray gun by gravity by raising and lowering the paint supply tank and adjusting it to a position higher than the spray gun;
A collection tank for collecting paint that is not discharged from the spray gun;
The present invention relates to a spraying amount control device for a coating apparatus, characterized by comprising pressurized air supply means for supplying pressurized air to the paint supply tank and pressurizing it.

  In the spray amount control device of the coating apparatus, a discharge amount detection device for detecting a discharge amount of the paint discharged from the spray gun, and a paint discharge from the spray gun when the height of the paint supply tank is variously changed. By detecting and inputting the discharge amount with the discharge amount detection device, the relationship between the height position of the paint supply tank and the discharge amount of the paint by the spray gun is obtained in advance, and a command signal for the target discharge amount by the spray gun It is preferable to provide a controller that issues a control signal to the tank lifting device to adjust the height of the paint supply tank so that a target discharge amount of paint is discharged from the spray gun.

  In the spray amount control device of the coating apparatus, it is preferable to have a circulation pipe for returning the paint in the paint recovery tank to the paint supply tank.

  According to the spray amount control method and apparatus for a coating apparatus of the present invention, the paint supply tank is adjusted to a position higher than the spray gun, the paint in the paint supply tank is supplied to the spray gun by gravity, and a part of the paint is supplied. The paint that is discharged from the spray gun and sprayed by the atomizing air and the paint that is not discharged from the spray gun are collected in the collection tank, so that the paint supplied by gravity is stable without causing fluctuations in the flow rate. It is possible to prevent the problem of powder precipitation and to achieve excellent effects that the discharge of the paint by the spray gun is stabilized.

  Furthermore, since the flow rate of the paint supplied to the spray gun is adjusted by adjusting the height position of the paint supply tank, the discharge speed related to the discharge amount of the paint of the spray gun can be arbitrarily set, Therefore, it is possible to achieve an excellent effect that a thin and uniform coating film can be accurately formed by ejecting a small flow rate of paint from the spray gun stably and accurately.

It is a block diagram which shows the reference example of the coating device in this invention. Is a block diagram illustrating an embodiment of a coating apparatus in the present invention. It is a block diagram which shows an example of the initial stage coating apparatus which the present inventors implemented. It is a diagram which shows the relationship between the supply pressure of the coating material supply tank in the coating apparatus of FIG. 3, a coating material collection | recovery tank pressure, and discharge pressure.

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

FIG. 1 shows a reference example of a coating apparatus according to the present invention. In the figure, reference numeral 50 denotes a spray gun for spraying paint a to perform coating, and 51 denotes a spray gun 50 which supplies paint a through a paint supply pipe 52. The paint supply tank 51 is supported by a tank lifting / lowering device 53 so that its height position can be arbitrarily adjusted. The paint supply pipe 52 is constituted by a flexible pipe. When the height of the paint supply tank 51 is adjusted to a position higher than the spray gun 50 by the tank lifting / lowering device 53, the paint a in the paint supply tank 51 can be supplied to the spray gun 50 by gravity. The spray gun 50 is provided with opening / closing means such as a needle valve (not shown), and a part of the paint a supplied from the paint supply tank 51 through the paint supply pipe 52 is a spray gun 50 in which the needle valve is opened. And atomized by the atomizing air 55 from the atomizing air supply device 54 and sprayed from the tip 50 a of the spray gun 50.

  Further, most of the paint a ′ that is not discharged to the spray gun 50 is collected by a collection tank 57 provided in the lower part through a collection pipe 56. 58 is a level meter for measuring the level of the recovered paint a ′ in the recovery tank 57.

  Further, the paint a in the recovery tank 57 can be circulated and supplied to the paint supply tank 51 through a circulation pipe 60 provided with a circulation pump 59. 59a is a flow meter for detecting the flow rate of the paint a circulated by the circulation pipe 60. The paint supply tank 51 and the recovery tank 57 are provided with stirrers 51a and 57a for stirring the paint a inside.

  The tank lifting device 53 may be any device that can arbitrarily adjust the height position of the paint supply tank 51 such as an electric cylinder or a hydraulic cylinder, but an electric cylinder is preferably used.

  The spray gun 50 was discharged from the spray gun 50 in a state where the supply of the atomizing air 55 from the atomizing air supply device 54 was stopped to the lower part of the tip 50a for spraying the paint of the spray gun 50. An optical sensor 63 (discharge amount detection device) comprising a light projector 61 and a light receiver 62 is provided to detect the dropping of the coating liquid droplet X that sometimes drops. The dropping of the liquid droplet X detected by the optical sensor 63 is provided. The controller 63 measures the discharge amount of the paint discharged from the spray gun 50 from the signal 63a. Further, a pressure gauge 65 for detecting the pressure of the paint a supplied to the spray gun 50 is provided at the inlet of the spray gun 50, and a pressure signal 65 a detected by the pressure gauge 65 is input to the controller 64. Yes.

  Droplets dropped from the spray gun 50 when the supply pressure of the paint a detected by the pressure gauge 65 at the inlet of the spray gun 50 is changed by adjusting the height of the paint supply tank 51 by the tank lifting device 53. The relationship between the height position of the paint supply tank 51 and the discharge amount of the paint a by the spray gun 50 is determined in advance by measuring the X dropping interval by the optical sensor (discharge amount detection device) 63, and the relationship is controlled. When the command signal S for an arbitrary target discharge amount is input, the controller 64 issues a control signal S ′ to the tank lifting / lowering device 53 so that the target discharge amount is maintained. The height position of the supply tank 51 is automatically controlled.

  Further, in FIG. 1, in order to clean the paint supply tank 51, the spray gun 50, the recovery tank 57, and the pipes 52, 56, 60, the cleaning water is provided by a cleaning water passage 67 having an opening / closing valve 66 in the recovery tank 57. 68 and a cleaning drain pipe 70 is connected to the recovery pipe 56 via a three-way valve 69. Reference numeral 71 denotes a drainage tank.

  FIG. 1 shows a case where the spray gun 50, the paint supply tank 51, the tank lifting / lowering device 53, the recovery tank 57, the circulation pump 59, and the drainage tank 71 are provided in the explosion-proof booth 72. Therefore, explosion-proof specifications are used for the tank lifting device 53 and the circulation pump 59.

  73 is an air panel provided outside the explosion-proof booth 72. A part of the air 74 ′ after the factory air 74 is taken into the air panel 73 and passed through a purifier 75 such as a dryer, an air filter, and a mist separator. Is supplied to the spray gun 50 as atomizing air 55 via the atomizing air supply device 54 having a pressure setting device 76, a switching valve 77, a flow meter 78, and the like. A part of the air 74 ′ from the purifier 75 is supplied to the spray gun 50 as cylinder drive air 79 via the pressure setting device 76 and the switching valve 77 to open and close a needle valve (not shown) of the spray gun 50. It comes to control.

  Further, a part of the air 74 ′ from the purifier 75 is supplied to the on-off valve 66 and the three-way valve 69 as valve operating air 80 via the pressure setter 76 and the switching valves 77 a and 7 b to switch the valves. Is supposed to do.

  In addition, an on-off valve 81 is provided upstream of the pressure gauge 65 in the paint supply pipe 52, and a part of the air 74 ′ from the purifier 75 passes through the pressure setter 76 and the switching valve 77 to operate the valve operation air. 82 is supplied to the on-off valve 81 to switch the valve.

  On the other hand, the air 74 ′ that has taken in the factory air 74 and passed through the purifier 75 ′ and the like passes through the pressure setting device 76 and the changeover valve 77, and serves as the stirring air 83 and the stirrer 51 a provided in the paint supply tank 51 and the recovery tank 57. , 57a are driven.

The operation of the reference example of FIG. 1 will be described below.

  When the on-off valve 81 is opened by the valve operating air 82 in a state where the paint supply tank 51 containing the paint a is held at a position higher than the spray gun 50 by driving the tank lifting / lowering device 53, the inside of the paint supply tank 51 The paint a is supplied to the spray gun 50 through the paint supply pipe 52 by gravity, and a part of the paint a is discharged from the spray gun 50.

  Further, the remaining paint a ′ that has not been discharged by the spray gun 50 is collected in a collection tank 57 by a collection pipe 56.

  At this time, when the supply pressure of the paint a detected by the pressure gauge 65 at the inlet of the spray gun 50 is variously changed by adjusting the height of the paint supply tank 51 by the tank lifting / lowering device 53, it is dropped from the spray gun 50. The drop interval of the droplet X to be measured is measured by an optical sensor (discharge amount detection device) 63, and the relationship between the height position of the paint supply tank 51 and the discharge amount of the paint a from the spray gun 50 is obtained in advance. 64, when the command signal S for the target discharge amount is input to the controller 64, the controller 64 causes the tank lifting device to be at the height position of the paint supply tank 51 where the target discharge amount is held. 53 is automatically controlled.

  As described above, when the atomizing air 55 from the atomizing air supply device 54 is supplied to the spray gun 50 in a state where the target amount of the paint a is discharged from the spray gun 50, the discharged paint is atomized. And sprayed from the tip 50a of the spray gun 50. The coating is performed in a state where the paint is stably sprayed from the spray gun 50.

  As described above, since the paint a in the paint supply tank 51 is supplied to the spray gun 50 by gravity, problems of pulsation due to paint precipitation and flow path resistance can be reduced. Since the flow of the paint a is stabilized, the coating quality in the case where a thin paint film is repeatedly applied by spraying a small flow rate of paint from the spray gun 50 can be greatly improved.

  Further, a part of the paint a supplied to the spray gun 50 by the paint supply tank 51 is discharged from the spray gun 50, and most of the paint a 'not discharged by the spray gun 50 is guided to the collection tank 57, whereby the spray gun Although the flow of the paint a with respect to 50 can be stabilized, the paint a in the paint supply tank 51 decreases in a short time. Therefore, the paint can be continuously applied by driving the circulation pump 59 and circulatingly supplying the paint a in the recovery tank 57 to the paint supply tank 51. The circulation pump 59 may be operated continuously, or may be operated when the paint level detected by the level meter 58 of the recovery tank 57 reaches a predetermined value.

  When the paint a in the recovery tank 57 is circulated and supplied to the paint supply tank 51 by the operation of the circulation pump 59, the amount of the paint a in the paint supply tank 51 increases, so the supply pressure of the paint a through the paint supply pipe 52 increases. Therefore, based on the pressure detected by the pressure gauge 65, the height position of the paint supply tank 51 can be corrected by the controller 64.

  Even when the painting operation is interrupted, the circulation pump 59 is operated to circulate the paint a through the paint supply tank 51 and the spray gun 50, thereby preventing the powder of the paint a from being precipitated.

  When the coating apparatus is cleaned after the painting operation is completed, the on-off valve 66 is opened by the valve operating air 80, the cleaning water 68 is supplied to the recovery tank 57 by the cleaning water passage 67, and then the circulation pump 59 is driven. Then, the cleaning water in the recovery tank 57 is guided to the paint supply tank 51 through the circulation pipe 60 and is further returned to the recovery tank 57 through the spray gun 50 through the paint supply pipe 52. Thereafter, the three-way valve 69 is switched by the valve operating air 80, the circulation pump 59 is driven, and the cleaning water in the recovery tank 57 is guided to the paint supply tank 51 through the circulation pipe 60. After passing through the gun 50 and the three-way valve 69, the water is drained to the drain tank 71 through the cleaning drain pipe 70.

FIG. 2 shows an embodiment of the coating apparatus according to the present invention. In FIG. 2, the coating material supply tank 51 shown in FIG. Pressure air supply means 86 for supplying a part of the air 74 ′ to the paint supply tank 51 through the pressure setting device 76 and the switching valve 77 as the pressurized air 85. Pressurization with pressurized air 85 is enabled.

  According to the embodiment of FIG. 2, in addition to adjusting the supply pressure of the paint a supplied to the spray gun 50 by changing the height position of the paint supply tank 51 by the tank lifting device 53, The supply pressure of the paint a can be further increased by the pressure of the pressurized air 85. Thus, the supply pressure of the paint a can be easily set to a high pressure by the pressure of the pressurized air 85.

  Therefore, the supply pressure of the coating material a can be increased even if the elevation height of the coating material supply tank 51 by the tank lifting device 53 is reduced, so that the tank lifting device 53 can be made small. At this time, the tank lifting / lowering device 53 can be used only for fine adjustment of the supply pressure.

  In addition, this invention is not limited only to the said form, Of course, a various change can be added in the range which does not deviate from the summary of this invention.

DESCRIPTION OF SYMBOLS 50 Spray gun 51 Paint supply tank 52 Paint supply piping 53 Tank raising / lowering device 55 Air for atomization 56 Recovery piping 57 Recovery tank 59 Circulation pump 60 Circulation piping 63 Optical sensor (discharge amount detection device)
64 Controller 65 Pressure gauge 85 Pressurized air 86 Pressurized air supply means a Paint

Claims (6)

A paint supply tank can be moved up and down, and the paint supply tank is adjusted to a position higher than the spray gun to supply the paint in the paint supply tank to the spray gun by gravity, and a part of the paint is discharged from the spray gun. The paint that is not discharged from the spray gun is collected in a collection tank by a collection pipe , pressurized air is supplied to the paint supply tank, and the supply pressure of the paint supplied to the spray gun is reduced. injection amount control method of the coating apparatus, characterized in that to increase.   When the height of the paint supply tank is variously changed, the amount of paint discharged from the spray gun is measured by the discharge amount detection device, so that the height position of the paint supply tank and the amount of paint discharged by the spray gun are measured. The height of the paint supply tank is adjusted by raising and lowering the paint supply tank so that the target discharge amount by the spray gun is maintained based on the obtained relationship. A spraying amount control method for a coating apparatus.   The spray amount control method for a coating apparatus according to claim 1 or 2, wherein the paint in the paint recovery tank is returned to the paint supply tank for circulation. A paint supply tank for containing paint;
A spray gun connected to the paint supply tank via the paint supply pipe and discharging a part of the paint from the paint supply tank;
A tank lifting device that feeds the paint in the paint supply tank to the spray gun by gravity by raising and lowering the paint supply tank and adjusting it to a position higher than the spray gun;
A collection tank for collecting paint that is not discharged from the spray gun;
An injection amount control device for a coating apparatus, comprising: pressurized air supply means for supplying pressurized air to the paint supply tank to pressurize the paint supply tank . A discharge amount detection device for detecting the discharge amount of the paint discharged from the spray gun, and a discharge amount detection device for detecting the discharge amount of the paint discharged from the spray gun when the height of the paint supply tank is variously changed. The relationship between the height of the paint supply tank and the amount of paint discharged by the spray gun is obtained in advance, and when the command signal for the target discharge amount by the spray gun is input, the target from the spray gun The spray amount of the coating apparatus according to claim 4 , further comprising: a controller that adjusts the height of the paint supply tank by issuing a control signal to the tank lifting device so that a discharge amount of the paint is discharged. Control device. The spray amount control device for a coating apparatus according to claim 4 or 5 , further comprising a circulation pipe for returning the paint in the paint recovery tank to the paint supply tank.

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