JP3583196B2 - Paint supply device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a paint supply device that quantitatively supplies paint to a coating machine by an air operated regulator disposed upstream of a paint supply pipe and a gear pump disposed downstream thereof.
[0002]
[Prior art]
In coatings that require strict uniformity of coating quality, such as automotive coatings, air-operated regulators and gear pumps are used in combination with coating machines to maintain a constant flow rate of coating sprayed from the coating machine. There has been proposed a coating material which strictly supplies a constant amount of paint (see JP-A-6-134359, JP-A-170284 and JP-A-254449).
[0003]
FIG. 2 shows such a conventional paint supply device, in which a color change device 51 having a large number of color change valves for selectively selecting paint of an arbitrary color from multicolor paints and a coating machine 52 are provided with a paint supply pipe 53. The paint supply pipe 53 is provided with an air operated regulator 54 for adjusting the supply pressure of the paint on the upstream side, and a gear pump 55 for adjusting the supply flow rate of the paint on the downstream side. ing.
[0004]
Here, if the gear pump 55 is rotated at a constant speed, the paint can be supplied at a constant flow rate because the gear pump 55 is excellent in quantitative performance. However, if the pressure of the paint flowing into the gear pump 55 fluctuates at this time, the gear pump 55 is rotated. The flow rate of the paint discharged from the nozzle 55 also slightly varies. For this reason, conventionally, the pressure of the paint flowing into the gear pump 55 is kept constant by the air operated regulator 54 installed on the upstream side of the gear pump 55, thereby preventing the fluctuation of the paint flow rate discharged from the gear pump 55. I have.
[0005]
[Problems to be solved by the invention]
However, when the paint supplied in a fixed amount by the gear pump 55 in this way was strictly measured, it was found that the paint was not supplied at a flow rate corresponding to the rotation speed. Thus, the present inventors have conducted intensive studies in pursuit of the cause. As a result, even if the pressure Pin on the inlet side of the gear pump 55 is kept constant by the air operated regulator 54, the pressure Pout on the discharge port side is maintained. And the pressure difference caused an error in the supply flow rate.
[0006]
FIG. 3 is a graph showing the relationship among the rotation speed of the gear pump 55, the pressure on the discharge port side, the pressure on the inlet port (set pressure of the air operated regulator 54), the set flow rate, and the discharge flow rate. It can be seen that the pressure Pin on the inflow port side of the gear pump 55 is maintained constant by the air operated regulator 54, and the pressure Pout on the discharge port side of the gear pump 55 increases as the number of rotations increases. Therefore, at the point where the pressure Pin on the inlet side and the pressure Pout on the discharge port overlap, a relationship of Pin> Pout occurs at a portion where the rotation speed is lower, and a relationship of Pin <Pout at a portion where the rotation speed is higher than that. Create a relationship.
[0007]
As the pressure difference between the inlet side and the discharge side of the gear pump 55 increases, the paint leaks from the high pressure side to the low pressure side through a small gap between the casing and the gear of the gear pump 55, and pressure paint is supplied with paint leaks set flow rate Q ₀ or more flow Qout to the discharge port side from the inflow port side at high speed rotation range, the flow from the discharge port side in the pressure at the discharge port side is high speed rotation range There is a problem that the paint flows backward to the inlet side and the paint is supplied at a flow rate equal to or less than the set flow rate. Particularly in recent years, the diameter of the paint supply pipe 53 has been reduced in order to reduce the amount of residual paint to be discarded when performing color change in the color change apparatus 51. Since the pressure in 53 greatly fluctuates, when the paint flow rate is frequently changed, the pressure fluctuation cannot be ignored.
[0008]
When the gear pump 55 is rotated at a constant speed and the pressure Pout on the discharge port side rises for some reason, the paint is prevented from being supplied at a flow rate higher than the set flow rate. There has also been proposed a paint supply apparatus that maintains the paint at a set flow rate by adjusting the valve opening of the air operated regulator 54 so as to reduce the pressure Pin on the side (see Japanese Patent Application Laid-Open No. 6-134359).
[0009]
However, this is to eliminate the disturbance of quantitativeness caused by the pressure fluctuation when the gear pump 55 is rotated at a constant rotation speed, and to reduce the flow rate caused by the pressure fluctuation when the rotation speed of the gear pump 55 is changed. Errors cannot be offset. For example, when the rotation speed is increased to increase the discharge flow rate of the gear pump 55, the pressure Pout on the discharge port side gradually increases, and accordingly, the pressure Pin on the inlet port adjusted by the air operated regulator 54 becomes Conversely, the pressure is controlled so as to decrease, and the pressure difference between the two increases, so that the paint leaks from the discharge port side to the inflow port side, and an error from the set flow rate increases.
In view of the above, the present invention provides a technology that enables a paint to be supplied accurately and quantitatively at a set flow rate according to the rotation speed of the gear pump without leaking the paint through a small gap between the casing of the gear pump and the gear. Is a subject.
[0010]
[Means for Solving the Problems]
In order to solve this problem, the present invention provides an air-operated regulator that regulates the supply pressure of paint on the upstream side of a paint supply pipe that supplies paint to a coating machine, and supplies a supply flow rate of paint on the downstream side. In a paint supply device in which a gear pump for adjusting
And a drive control device for rotating the gear pump at a rotational speed corresponding to the set flow rate of the paint to be supplied to the coating machine, the gear pump in accordance with the set flow rate or flow rate of the paint to be output as the drive control device or et flow amount data and a set rotational speed pressure control device for variably controlling the set pressure of the air operated regulator based on, the pressure control device, the pressure at the discharge port side of the gear pump when operating the gear pump at the desired set flow rate, A flow data-set pressure conversion table stored in association with the flow data output from the drive control device, and a setting corresponding to the flow data by referring to the conversion table when the flow data is output from the drive control device. A pressure setting device for outputting pressure is provided.
[0011]
According to the present invention, since the set pressure of the air operated regulator is directly determined from the flow rate data such as the set flow rate of the paint and the set rotation speed of the gear pump, the pressure on the discharge side of the gear pump or the flow rate is detected one by one. It is possible to adjust the valve opening of the air operated regulator from the beginning of the operation at an optimum set pressure according to the set flow rate of the paint without the need to compare with the set pressure of the air operated regulator.
Therefore, the paint does not leak between the inflow port side and the discharge port side of the gear pump, and the paint can be quantitatively supplied to the coating machine at a set flow rate of the gear pump with extremely high accuracy.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. FIG. 1 is a flow sheet showing a paint supply device according to the present invention, FIG. 2 is a flow sheet showing another embodiment, and FIG. 3 is a flow sheet showing another paint supply device according to the present invention.
[0013]
In the drawing, reference numeral 1 denotes a paint supply device which supplies each paint selectively selected by a color changing device 3 having color changing valves 2, 2,... To a coating machine 4, and includes a color changing device 3 and a coating machine. An air-operated regulator 6 for adjusting the supply pressure of the paint and a gear pump 7 for adjusting the supply flow rate of the paint are interposed in a paint supply pipe 5 connecting the feed pump 4 with the air-operated regulator 6 on the upstream side and the gear pump 7 on the downstream side. It is installed in.
[0014]
The gear pump 7 includes a pump body 8 and a drive motor 9, and is driven by the drive control device 10 at a rotation speed according to the set flow rate when the flow rate of the paint to be supplied to the coating machine 4 is set.
The drive control device 10 stores in advance a set flow rate / rotation speed conversion table in which the number of rotations is set according to the set flow rate. The rotation speed of the gear pump 7 according to the flow rate is read out with reference to the driving motor 9 to drive the pump body 8.
[0015]
The set pressure of the air operated regulator 6 can be adjusted without feedback control or comparison with the pressure on the discharge port 7out side, such as the set flow rate output from the drive control device 10 or the set rotational speed corresponding thereto. Open loop control is performed by the pressure control device 31 based on the flow rate data, and the pressure of the air pressure-fed from the operated air supply source 17 to the air operated regulator 6 is adjusted by the electro-pneumatic converter 18. .
[0016]
The pressure control device 31 stores the pressure at the discharge port 7out side of the gear pump 7 when the gear pump 7 is operated at a desired set flow rate in correspondence with the flow rate data output from the drive control device 10. A set pressure conversion table 32 and a pressure setter 33 that outputs a set pressure corresponding to a set flow rate with reference to the conversion table 32 are provided.
[0017]
Numeral 34 denotes a valve device which divides the paint supply pipe 5 into the color changing device 3 and the coating machine 4 before the coating machine 4 during the color changing cleaning. A dump valve 36 for discharging the cleaning solvent and the cleaning air that have cleaned the inside 5 to the collection tank 35, and cleaning valves 37 and 37 for supplying the cleaning solvent and the cleaning air for cleaning the coating machine 4 are provided.
Reference numeral 38 denotes a bypass passage that bypasses the gear pump 7 during color change cleaning and directly connects the paint supply pipes 5b and 5a. The cleaning solvent and the cleaning air supplied from the color change device 3 do not pass through the gear pump 7. Only the inside of the paint supply pipe 5 can be cleaned in a short time.
Further, a cleaning solvent is supplied into the pump main body 8 of the gear pump 7 through the shaft cleaning channel 39 so that the paint adhered to the gap between the gear and the casing, the gap between the rotating shaft and the gear, and the like is washed. It has been made.
[0018]
According to this, at the same time as the gear pump 7 is operated by the drive control device 10 at the number of revolutions corresponding to the set flow rate of the paint, for example, data of the set flow rate is output from the drive control device 10 as flow rate data.
Therefore, if the set pressure corresponding to the set flow rate is stored in the flow rate data-set pressure conversion table 32 of the pressure control device 31, the conversion table 32 is referred to when the drive control device 8 outputs the set flow rate. The set pressure of the air operated regulator 6 corresponding to the set flow rate is read out, and the pressure of the air operated regulator 6 is set by the pressure setting device 33.
[0019]
As a result, the valve opening of the air operated regulator 6 is adjusted, and the pressure at the inlet 7in of the gear pump 7 is controlled to be equal to the pressure at the outlet 7out. The paint does not leak between the outlets 7out, so that the paint can be supplied very accurately at a flow rate equal to the set flow rate.
In this case, in the case where the rotation speed is used as the flow data, if the set pressure corresponding to the rotation speed is stored in the flow data-set pressure conversion table 32, the rotation speed is output from the drive control device 10. Then, the set pressure of the air operated regulator 6 corresponding to the rotation speed is read out with reference to the conversion table 32, and the pressure of the air operated regulator 6 is set by the pressure setting device 33.
[0020]
【The invention's effect】
As described above, according to the present invention, the pressure on the inflow port side is previously set to be equal to the pressure on the discharge port side of the gear pump in accordance with the flow rate of the paint to be supplied. At the same time, there is a very excellent effect that the fixed amount can be supplied accurately at the set flow rate.
[Brief description of the drawings]
FIG. 1 is a flow sheet showing an example of a paint supply device according to the present invention.
FIG. 2 is a flow sheet showing a conventional apparatus.
FIG. 3 is a graph showing a relationship among rotation speed, pressure, and flow rate.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 paint supply device 4 paint machine 5 paint supply pipe 6 air operated regulator 7 gear pump 10 drive control device 31 pressure control device

Claims (1)

An air-operated regulator that adjusts the paint supply pressure is installed upstream of the paint supply pipe that supplies the paint to the coating machine, and a gear pump that adjusts the paint supply flow rate is installed downstream. In the device,
And a drive control device for rotating the gear pump at a rotational speed corresponding to the set flow rate of the paint to be supplied to the coating machine, the gear pump in accordance with the set flow rate or flow rate of the paint to be output as the drive control device or et flow amount data A pressure control device that variably controls a set pressure of the air operated regulator based on the set rotation speed ,
The pressure control device is a flow data-set pressure conversion table in which the pressure on the discharge port side of the gear pump when the gear pump is operated at a desired set flow rate is stored in correspondence with the flow data output from the drive control device. And a pressure setting device that outputs a set pressure corresponding to the flow rate data by referring to the conversion table when the flow rate data is output from the drive control device.

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