JPH0626710B2 - Discharge rate control method for multi-liquid coating equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is a coating apparatus for mixing a plurality of coating liquids and discharging the coating liquids toward an object to be coated, by measuring the flow rate of each of the coating liquids discharged. The present invention relates to a discharge amount control method for a multi-liquid coating apparatus, which controls the rotation speed of a coating liquid delivery gear pump.

(Prior Art) When a plurality of coating liquids are mixed and coating is performed, for example, in order to mix and discharge a main agent such as a polyol and a curing agent such as an isocyanate, as shown in FIG. 2 and the main agent supplied through the pipe 2a by the hardener Kunk 3 and the pipe 4 by the gear pump 4.
The curing agent supplied through a is mixed in the mixer 5 and discharged from the spray gun 6. At this time, on the premise that the flow rate of the coating liquid supplied through the gear pumps 2 and 4 is uniquely determined by the rotation speed of the gear pump, the method of controlling the rotation speed of the gear pump to a required value, The discharge rate was controlled.

Further, as shown in FIG. 7, the main agent is supplied from the pipe 7 by a plunger pump (not shown) or by pressure feeding, the supply amount is detected by the flow meter 7a, and the detected value is controlled by the controller 8. There is a method in which the amount of the curing agent required to keep the mixing ratio constant is calculated and the rotation speed of the gear pump 9 is controlled to keep the mixing ratio constant (Japanese Patent Laid-Open No. 52-2).
See No. 761).

(Problems to be solved by the invention) In the method shown in FIG. 6, however, the discharge amounts of the gear pumps 2 and 4 are the viscosity after coating and the inlet side of the gear pump even when the rotation speed of the gear pump is constant. And the pressure difference on the outlet side. The rate of change varies depending on the type of gear pump, but even if the number of rotations of the gear pump is constant, the fluctuation of the discharge amount is 5 to 20 compared to the initial value.
It was confirmed that it could reach cc / min.

When the control method shown in FIG. 7 is used, the gear pump 9
Even if the number of revolutions is in accordance with the command, it is not possible to ensure the quantitativeness of the amount of discharge with respect to the number of revolutions of the pump, so that the total amount of discharge fluctuates. Further, the main agent sent from the pipe 7 is detected by the flow meter 7a, and when the control device 8 controls the rotation speed of the gear pump 9, the control time delay causes an abnormality in the mixing ratio. Generally, the discharge amounts of the gear pumps 2, 4 and 9 vary depending on the differential pressure, the viscosity, etc. even if the rotation speed is the same, but the state of change of the discharge amount is shown in FIG. In addition, in FIG. 8, the fluctuation range is shown between the lines.

If a change in the discharge amount occurs in this way, dripping, sinking,
If a coating failure such as occurs and the mixing ratio becomes abnormal, delamination occurs, and a good coated surface cannot be obtained. The present invention has been made to solve these problems so that a predetermined discharge amount can always be obtained with a predetermined mixing ratio.

(Means for Solving the Problems) As a means for solving the above problems, the present invention is a multi-liquid coating apparatus supplied by a gear pump, in which a gear pump is rotated at two preset levels before coating. The discharge amount of the gear pump is detected, the rotation number of the gear pump for obtaining the target discharge amount is calculated based on the measured discharge amount, this is stored as a set value, and the gear pump is rotated according to the set value. It is the one.

(Operation) As a result, the discharge amount from the gear pump is based on the actually measured value, and therefore no error occurs. In addition, using the measured values at the preset two levels of rotation speed,
For other rotation speeds, the gear pump rotation speed for the required discharge amount is calculated by the interpolation method, etc., and the gear pump is driven at this rotation speed. It is possible to prevent the occurrence of coating defects such as peeling.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the relationship between the rotational speed and the flow rate of the gear pump of FIG. 2 in the present invention. FIG. 2 shows the multi-liquid coating apparatus of FIG. 6 to which the apparatus used in the present invention is added, and the same members as in FIG. 6 are designated by the same reference numerals. In FIG. 2,
The mass flowmeter 10 is inserted between the gear pump 2 and the mixer 5, and the electric wire 11 is connected to the inverter 12 by the mass flowmeter 10.
It is connected to the. The inverter 12 has a function of storing and calculating the relationship between the number of rotations of the gear pump and the discharge amount, etc., as described later, calculates the signal from the mass flowmeter 10, and uses the conductor 13 to set the next electric motor 14 to a predetermined value. Drive to rotate at the number of rotations. Further, a mass flowmeter 15 is inserted between the gear pump 4 and the mixer 5, and an electric wire 16, an inverter 17, a conductor 18, and an electric motor 19 are connected to perform the same function. Then, the electric motors 14 and 19 rotate the gear pumps 2 and 4, and the coating liquid is sent to the mixer 5.

At this time, however, a storage device equivalent to the graph showing the relationship between the rotation speed of the gear pump and the discharge amount (flow rate) of the gear pump as shown in FIG. 1 is installed in the arithmetic unit in the inverters 12, 17. ing. The inverter 12 stores the data related to the gear pump 2 and is stored in the high rotation speed range.
The theoretical value of the flow rate V _{10 at} the rotation speed R ₁₀ (for example, 200 rpm) is initially stored as the set value. Then, the mass flowmeter 10 measures the flow rate at a rotation speed of R ₁₀ (200 rpm) and stores the measured value of Vr _{1 in} a storage device corresponding to a graph (FIG. 1). Further, the value of the flow rate V ₁₁ based on the theoretical value in the low rotation speed range R ₁₁ (for example, 80 rpm) is stored as a set value, and the mass flow meter 10 rotates the rotation speed R ₁₁ (80 rpm).
The flow rate is measured and the measured value Vr ₂ is stored in a storage device corresponding to the graph (FIG. 1). According to the theoretical value V ₁₀ V ₁₁ , the discharge rate should be 300 g / min and 120 g / min for the rotation speed of 200 r.pm 80 r.pm, but the viscosity of the coating liquid and the gear pump 2 Due to the pressure difference between the inlet and outlet sides, the actual flow rates Vr ₁ and Vr ₂ are theoretical flow rates V ₁₀ and Vr.
Different from ₁₁ . At this point, the actual flow rate Vr ₁ in the high speed range R ₁₀ and the theoretical flow rate V ₁₀ and the actual flow rate in the low speed range R ₁₁
Vr ₂ is compared with the theoretical flow rate V ₁₁ . In this case V ₁₀ and V
If either the difference between r ₁ or the difference between V ₁₁ and Vr ₂ is larger than T% (for example, 15%) of the theoretical flow rates V ₁₀ and V ₁₁ , the pipe system may be ruptured or blocked. It is judged as an abnormality due to and the coating equipment is stopped. The difference between V ₁₀ and Vr ₁ , and
If both of the differences between V ₁₁ and Vr ₂ are equal to or less than T% of the theoretical flow rate, the rotation speed of the gear pump is set based on the measured values Vr ₁ and Vr ₂ . Specifically, the measured values Vr ₁ Vr _{2 in} Fig. ₁
Draw a straight line that connects to and use the value on the straight line as the standard for setting the gear pump rotation speed for the required flow rate. That is, in order to set the rotation speed of the gear pump 2 for obtaining the first target flow rate V ₁₂ , a straight line Wa is drawn from the flow rate V _{12 on the} vertical axis in the horizontal direction, and the line Wa is directed downward at the intersection with the straight line Y. Draw a straight line Wb. This first object flow V ₁₂ rpm R ₁₂ in which gear pump 2 corresponding to the are set. The rotation speed of the gear pump 2 for the second target flow rate V ₁₃ is also set to R ₁₃ by the straight lines Wc and Wd.

Although the gear pump 2 has been described above, the rotation speed for the target flow rate is similarly set for the gear pump 4 by similarly storing it in the inverter 17. Due to the difference in flow rate, the rotation speed in the high speed range is 200r.
For example, 100r.pm instead of pm, 8 at low rpm
For example, 40r.pm is used instead of 0r.pm, and the flow rate is different from 300g / min to 50g / min, but the idea is exactly the same, and a storage device equivalent to that in FIG.
It is installed in the inverter 17 and has a similar function.

In this way, the rotation speed for each target flow rate is set for each gear pump, the multi-liquid paint coating preparation consisting of the main agent and the curing agent is completed, and if this is operated, the gear pump 2,
4 rotates at a rotational speed capable of discharging the respective target flow rates, and supplies the paint to the mixer 5. After being sufficiently mixed by the mixer 9, it is sprayed from a spray gun 10 toward an object to be coated (not shown). FIG. 3 is a flowchart showing this process.

Next, the coating device is actually operated, and the state of change in the mixing ratio when the paints are mixed is measured. FIG. 4 is a result of investigation over 7 days by setting the rotation speed of the gear pump according to the embodiment of the present invention, and shows that the mixing ratio is ± 2% or less, which is excellent for an allowable width of 10%. When coating was performed at this mixing ratio, no coating defects such as delamination, dripping, or sinking occurred in any of the coatings. Using a coating apparatus similar to that of this example, the mixing ratio was investigated over a period of 7 days with the rotation speeds of the gear pumps 2 and 4 fixed. As shown in FIG. The width changed to 5 times when the mixing ratio deviated from the permissible width of ± 10%. When this mixed paint was applied to the article to be coated, delamination was observed during the painting.

(Advantages of the Invention) Since the present invention has the above-described configurations and operations, it is possible to supply paints of a plurality of discharge amount levels with high accuracy without control delay, and thus to achieve predetermined accuracy. A mixed liquid having a high mixing ratio can be obtained. Therefore, there is an effect that it is possible to prevent coating defects such as delamination, dripping, and sinkage after coating.

Further, when the method of the present invention is used, even if there is a slight flow rate fluctuation due to wear of the gear pump, the supply amount is corrected if it is below a certain value, so that the period of use of the gear pump can be extended. Further, since the flow rate is corrected even if the viscosity of the coating liquid is slightly different, it is not necessary to strictly control the temperature of the coating liquid as in the conventional case, which can contribute to the cost reduction of the coating process. Further, since the abnormality of the device is detected and stopped at an early stage, the safety is improved.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the discharge amount of the gear pump and the number of revolutions and its set value, which is the main part of the present invention, FIG. 2 is a block diagram showing the configuration of the coating apparatus of the present invention, and FIG. FIG. 4 is a flow chart of the method of the present invention, FIG. 4 is a graph showing the mixing ratio when the coating liquids are mixed according to the embodiment of the present invention, and FIG.
The figure is a graph of the same method as that of FIG. 4 performed by the conventional method, FIGS. 6 and 7 are block diagrams showing the configuration of the conventional coating method, and FIG. It is a graph showing the state in which the discharge amount changes. 2,4 ...... Gear pump 10,15 …… Mass flowmeter 12,17 …… Inverter Vr ₁ …… High speed measurement flow rate Vr ₂ …… Low rotation range measurement flow rate

Claims (8)

[Claims] 1. A gear pump which has been preset before painting.
Detects the discharge rate at a standard number of rotations, calculates the rotation rate of the gear pump to obtain the target discharge rate based on the measured discharge rate, stores this as a set value, and stores the gear pump according to the set value. A method for controlling a discharge amount of a multi-liquid coating device, which is characterized by rotating. 2. The method according to claim 1, wherein in measuring the discharge amount of the gear pump, each liquid is actually discharged at the same time, and the discharge amount of each liquid is detected in this state. Discharge rate control method for liquid coating equipment. 3. A target discharge amount is calculated from a intercept and a slope of a linear expression represented by the straight line, by connecting a detected value of the discharge amount at the two levels of rotation speed.
A discharge amount control method for a multi-liquid coating apparatus according to claim 1. 4. The multi-speed gear pump according to claim 1, wherein the two levels of gear pump rotation speed are rotation speeds for obtaining discharge amounts close to the maximum discharge amount and the minimum discharge amount of each liquid used during normal painting. Discharge rate control method for liquid coating equipment. 5. The number of revolutions of the gear pump of the two levels,
The discharge amount control method for a multi-liquid coating apparatus according to claim 1, wherein the number of revolutions of each liquid is set so as to be close to a desired mixing ratio. 6. The method for controlling the discharge amount of a multi-liquid coating apparatus according to claim 1, wherein the discharge amount of the gear pump is detected by a mass flow meter provided upstream or downstream of the gear pump of each liquid. 7. The method for controlling the discharge amount of a multi-liquid coating apparatus according to claim 1, wherein the discharge amount of the gear pump is measured at the time of color change before coating or when spraying. 8. When measuring the discharge amount of the gear pump, the measured value is compared with a theoretical flow rate value, and if the difference exceeds a certain value, it is judged that the gear pump or the piping system is abnormal, and the control system is automatically stopped. Claim 1 characterized by
A method for controlling a discharge amount of a multi-liquid coating device according to the item.