JPS6243751B2 - - Google Patents

Description

Detailed Description of the Invention Technical Field The present invention relates to a device for adjusting the temperature of paint, particularly in a painting line having a plurality of paint tanks, which reduces variations in temperature between paint tanks and reduces fluctuations in paint discharge amount. Concerning the technology of forcing.

Prior Art In the painting process, controlling the amount of paint discharged is one of the most important things. If the discharge rate fluctuates, paint film defects such as so-called "wallpaper" (paint film is too thin) or "sag" (too much paint drips down) will occur, requiring post-treatment processes such as repairs. become. Changes in paint viscosity are one of the major factors that cause variations in the discharge amount, and changes in paint temperature have the greatest effect on changes in viscosity.
Therefore, in order to reduce the fluctuation in the discharge amount, it is sufficient to reduce the fluctuation in the paint temperature.

Incidentally, fluctuations in the amount of paint discharged become a particularly serious problem in paint lines having a plurality of paint tanks. That is, if the discharge amount of paint differs between paint tanks, the quality of the object to be painted (for example, an automobile body) will not be constant, and the rate of product failure will increase. Therefore, today, as coatings are becoming more diverse,
Controlling the temperature of the paint is extremely important in efficiently applying multi-colored paint, reducing variations between paint tanks, and forming a uniform paint film.

For this reason, conventional approaches have been to insulate the paint tank and paint circulation piping system to minimize the effects of fluctuations due to outside temperature, or to build the paint tank into a double tank structure and pour hot or cold water around the inner paint tank to maintain the paint temperature. Although adjustments were made, satisfactory results were not obtained.

FIG. 1 shows a paint temperature regulating device for a paint line according to the latest prior art. In the figure, 10 paint tanks _10-1 , _10-2 ,...10
- Assume that ₁₀ temperature adjustments are to be made (only 3 tanks shown). Circulation pumps _11-1 , _11-2 ,... _11-10 are provided in the tanks _10-1 to _10-10 , and paint pipes _13-1 , _13-2 ,...13-
₁₀ sends the paint to the paint booth (not shown);
The paint is returned to each tank _10-1 to 10-10 again by paint return pipes _{15-1 , 15-2} , . . . _15-10 . Each paint tank is an outer tank 17
_-1 , _17-2 ,... _17-10 , and has a double tank structure. Outer tank 17-1 _~ 10
- ₁₀ includes a pump 2 from a water tank 20 in order to adjust the temperature of the paint in the inner tanks _10-1 to _10-10 .
1, the main pipe 23, branch pipes _25-1 , _25-2 ,
... _25-10 , hot water or cold water is circulated and supplied. The hot or cold water for temperature adjustment in the outer tanks _17-1 to _17-10 is transferred to the inner tanks _10-1 to _10-10.
After exchanging heat with the paint inside, each return branch pipe 27-
₁ , _27-2 , ... _27-10 , and is returned to the water tank 20 via the main return pipe 39 . Note that 24 is a two-way valve that adjusts the flow rate of hot water or cold water for temperature adjustment. Hot water or cold water is stored in the water tank 6 depending on the season, and its temperature is controlled to a constant set temperature by an appropriate thermostatic heating device or cooling device (not shown).

In the above-described painting line, correction for changes in paint temperature due to changes in outside temperature is performed as follows. That is, for example, the paint pipes _13-1 , _13- of the first and last paint tanks _10-1 , 10-10
The average value of the temperatures measured by the temperature measuring devices _29-1 and _29-10 provided in _{the 10} is calculated by the average temperature calculator 26, and the output is inputted to the temperature controller 28, which sends an electric signal to the flow rate regulating valve 24. give. In this way, by changing the circulating flow rate of the temperature control fluid (hot water or cold water), the paint temperature is kept constant. However, this conventional method has the following drawbacks.

1. Since the paint temperature is controlled by changing the flow rate of the temperature control fluid, the amount flowing into the outer tank increases in the outer tank closer to the pump 21, and decreases as the distance moves away. You can't expect temperature control.

2. If the difference in outside temperature between daytime and nighttime is very large, it is practically impossible to control the paint temperature by changing the flow rate of the temperature control fluid (also, it requires a considerable amount of pump power, so it is difficult to (also not desirable). Therefore, the paint temperature cannot be maintained at the desired temperature.

OBJECT OF THE INVENTION The object of the present invention is to solve the above-mentioned drawbacks, and to maintain a substantially constant paint temperature throughout the year without any variation in paint temperature between paint tanks and without being affected by changes in outside temperature. Another object of the present invention is to provide an adjustment device.

Structure of the Invention According to the present invention, in order to achieve the above-mentioned object,
In a paint temperature control device having a double tank structure in which a paint temperature control fluid can be circulated around a plurality of paint tanks, a plurality of paint temperature control fluids containing a plurality of temperature control fluids having different set temperatures are used. a fluid tank; a plurality of independent piping systems connecting the fluid tank and an outer tank of each of the paint tanks;
A plurality of pumps are installed in each piping system to suck and exhaust the temperature regulating fluid in each fluid tank, and valves on the sending and return sides are installed in each piping system, and the pumps are installed in the respective piping systems to adjust the temperature of the paint. According to the above pump,
A paint temperature control device is provided that includes a switching drive device that selectively operates a feed-side shutoff valve and a return-side shutoff valve to switch a piping system.

According to yet another aspect of the present invention, in addition to the above-described configuration, a paint temperature control device is provided with a delay means for delaying the switching signal from the switching drive device to each return side or valve disconnection for a predetermined period of time. Equipment is provided.

EXAMPLE Hereinafter, an example (FIG. 2) of the present invention will be described in detail. In FIG. 2, parts that are the same as those in FIG. 1 are indicated by the same numbers, and the designation will be omitted. The main difference between the present invention and FIG. 1 is that hot water for temperature control and cold water (generally temperature control fluids with different set temperatures) are stored in separate water tanks 20A and 20B, respectively. The cold water tank 20A is connected to a main supply pipe 23 of hot water or cold water for temperature adjustment via a branch pipe 23A, and the hot water tank 20B is connected to a main water supply pipe 23 via a branch pipe 23B. A cold water pump 2 is installed in each of the branch pipes 23A and 23B.
1A and a hot water pump 21B are provided. Three-way valves 24A and 24B are arranged in the piping system between the cold water pump 21A and the cold water tank 20A and between the hot water pump 21B and the hot water tank 20B, respectively. The third port of each three-way valve 24A, 24B connects to the respective tank 20 via an overflow return pipe 41A, 41B.
Connected to A and 20B. Also, cold water pump 21
A. A feeder and valves 43A and 43B are provided on the discharge side of the hot water pump 21B. Further, branch pipes 39A and 39B of the cold water or hot water return pipe 39 are also provided with return valves 45A and 45B.

Furthermore, in the present invention, hot/cold water switching control drive (circuit) devices 51A, 51B are provided, which operate based on the output signal from the average temperature calculator 26,
Switch the circulation system. That is, when the measured value is above the set value, the hot water system drive device 51B is operated, and when it is below the set value, the cold water system drive device 51A is operated. Both drive devices 51A and 51B are connected via an inverter 56, for example, so that one of them is always in operation. The switching signals from the drive devices 51A, 51B are sent to the pumps 21A, 21B, feeder and valve 43.
A, 43B and the return valves 45A, 45B, respectively, but eventually the return valves 45
A, 45B are transmitted via delay timers 53A, 53B. All of the various shear valves and switching valves used in the present invention may be, for example, electromagnetic valves.

The apparatus of the present invention constructed as described above operates as follows.

1 When operating the hot water pump 21B (in the case of hot water operation) When the paint temperature is lower than the set temperature, the hot water system drive device 51B is activated, and the hot water pump 21B pumps the outer tank _17-1 of each paint tank from the hot water tank 20B. ~ _17-10 Hot water is circulated and supplied. Sending valve 43B, return valve 45
B is in the open position. At this time, the cold water pump 21
A does not work. Further, the feed valve 43A and the return valve 45A are closed. pump 21
A, 21B operation, non-operation, feeder and valve disconnection 4
3A, 43B and return valve 45A, 45B
The opening and closing of is controlled by signals from drive devices 51A and 51B.

2 When operating the cold water pump 21A (in the case of cold water operation) When the paint temperature is higher than the set temperature, the drive device 51A is activated, and contrary to the case 1) above, the cold water pump 21A moves from the cold water tank 20A to the outer tank. Chilled water is supplied in circulation. The feed valve 43A and the return valve 45A are in the open position. At this time, naturally the hot water pump 21
B is inactive, and its feed valve 43B and return valve 45B are both in the closed position.

Incidentally, the fluids in the hot water tank 20B and the cold water tank 20A are maintained at a predetermined set temperature by a thermostatic heating device or a cooling device, as in the case of FIG.

As described above, according to the present invention, by selectively using two types of temperature control fluids with different set temperatures, the paint temperature can be maintained at the set temperature substantially all the time while the amount of water supplied by the pump is constant. Furthermore, since the temperature of the paint is controlled by varying the temperature instead of changing the flow rate of the temperature regulating fluid, the drawbacks of the prior art described at the beginning are overcome.

Another major feature of the present invention is the control when switching from hot water to cold water or vice versa from cold water to hot water. That is, for example, when switching from hot water operation to cold water operation, the closing time of the hot water system return and shutoff valve 45B and the opening time of the cold water system return and shutoff valve 45A can be delayed by a predetermined time t by the delay timers 53A and 53B. . This prevents hot water from flowing into the cold water tank 20A and raising the temperature of the cold water tank 20A, for example, when switching from hot water to cold water. In addition, in the case of switching from cold water to hot water, in exactly the same manner, the timing of returning the cold water system and closing the shutoff valve 45A and the timing of returning the hot water system and opening the shutoff valve 45B are delayed by t. This relationship is shown in FIG. In the figure, a cold water system and a hot water system are shown, and t represents the above-mentioned delay time.

In this way, according to the present invention, there is no sudden temperature change in the liquid temperature in the hot water tank or cold water tank when switching from hot water to cold water or from cold water to hot water, and therefore the paint temperature can be easily maintained constant. Also, less energy is consumed to keep the temperature of the hot water tank or cold water tank constant. The delay time t is sufficient for the hot or cold water in the circulation system to be completely returned to the hot or cold water tank, respectively.

The capacities of the hot water tank 20B and the cold water tank 20A are preferably large enough to accommodate the amount of circulation in the main supply pipe 23 and the main return pipe 39.

Moreover, in the present invention, the three-way valves 24A, 24B
are controlled to open and close at the same time as the feeder and shutoff valves 43A and 43B by a signal from the temperature controller 28, but this is not to change the circulating amount of hot water or cold water as in the conventional case, but to switch from hot water to cold water or from cold water to hot water. To return the hot water or cold water upstream of the hot water pump or upstream of the cold water pump drawn by the hot water pump or cold water pump from the hot water tank or cold water tank to the hot water tank or cold water tank, respectively, through the overflow return pipes 41A and 41B when switching is performed. Helpful. If some hot water or cold water remains in the piping upstream of the hot water pump or cold water pump, it is susceptible to temperature changes in the outside air (as it is not subject to temperature regulation in the hot water tank or cold water tank). Therefore, when the hot water pump or cold water pump starts supplying hot or cold water again, the temperature of the hot water or cold water will temporarily deviate from the set value. In this sense, the three-way valve 24A,
24B is preferably provided as close as possible to the pumps 21A and 21B. The above explanation is based on the case where there are two temperature regulating fluid tanks, a hot water tank and a cold water tank, but even if there are three or more temperature regulating fluid tanks with different set temperatures, they can be appropriately switched. It is clear that exactly the same effect can be obtained by doing so.

Effects of the Invention As described above, according to the present invention, it is possible to uniformly and reliably control the paint temperature in a plurality of paint tanks in a simple manner, and it is possible to control the paint temperature in a plurality of paint tanks uniformly and reliably throughout the year, even in summer, winter, or the middle season where there is a large temperature change between day and night. A predetermined paint temperature can be maintained. Furthermore, since the temperature can be kept constant, the viscosity of the paint is also constant, and therefore there is no need to frequently change the set value of the paint discharge amount in response to changes in the viscosity of the paint.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a paint line of a paint temperature regulating device according to the prior art, FIG. 2 is a diagram showing a painting line of a paint temperature regulating device according to the present invention, and FIG. 3 is a diagram showing a painting line of a paint temperature regulating device according to the present invention. The figure which shows an example of control mode. _10-1 ~ _10-10 ...Paint tank, _17-1
~ _17-10 ...Outer tank, 20A...Cold water tank, 20B...Hot water tank, 21A...Cold water pump, 21B...Hot water pump, 24A, 24B...
Three-way valve, 43A, 43B... feeder valve, 45
A, 45B...Return or valve disconnection, 51A, 51B...
...Drive circuit.

Claims (1)

[Scope of Claims] 1. In a paint temperature control device having a double tank structure capable of circulating a paint temperature control fluid around a plurality of paint tanks, a plurality of paint temperature control devices with different set temperatures are provided. A plurality of fluid tanks containing fluid, a plurality of independent piping systems connecting the fluid tanks and the outer tanks of each of the paint tanks, and temperature control within each fluid tank provided within each piping system. A plurality of pumps for sucking and discharging the fluid, a stop valve on the sending side and a return side provided in each piping system, and a stop valve on the sending side and a stop valve on the return side according to the paint temperature. A paint temperature control device that has a switching drive device that selectively operates valves and valves to switch piping systems. 2. In a paint temperature control device having a double tank structure in which a paint temperature control fluid can be circulated around the outer circumference of a plurality of paint tanks, a plurality of paint temperature control fluids containing a plurality of temperature control fluids having different set temperatures are used. a fluid tank, a plurality of independent piping systems connecting the fluid tank and the outer tank of each of the paint tanks, and a plurality of independent piping systems provided in each piping system for sucking and discharging temperature regulating fluid in each fluid tank. A plurality of pumps, a stop valve on the sending side and a return side provided in each piping system, and depending on the temperature of the paint, the pump, the stop valve on the sending side, and the stop valve on the return side are set respectively. A paint temperature control device comprising a switching drive device that selectively operates to switch a piping system, and a delay means that delays a switching signal of inactivation from the switching drive device to each return side valve or valve for a predetermined period of time.