JPH04305277A - Drying method for coating - Google Patents

Abstract

PURPOSE:To simplify drying furnaces while corresponding to the differences in coating conditions to works W. CONSTITUTION:Plural coating lines CL1 to CL6 respectively have predrying furnaces PB1 to PB6 in addition to coating zones SP1 to SP6 for coating the works W with coating materials. One common normal drying furnace MB is provided for the above-mentioned plural coating lines CL1 to CL6. One or >=2 of the required coating lines are selected from the plural coating lines CL1 to CL6 according to the coating conditions required for the works W; for example, the requirements for metallic coating or solid coating or water- based coating. The selection of the coating lines is executed by transfer and reception of the works W to and from a transporting line ML continuous with the normal drying furnace MB by utilizing, for example, transfer devices J1 to J6. The drying in the normal drying furnace MB is executed only after the predrying in the coating line to be the final stage among the selected coating lines ends.

Description

[Detailed description of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for drying paint.

0003

2. Description of the Related Art A painting line for painting workpieces is equipped with a series of equipment from applying paint to the workpiece to completing drying of the applied paint. That is, for one painting line, there is a coating zone where paint is applied, and a setting zone where the applied paint is maintained at a low temperature such as room temperature and volatile components in the paint are evaporated.
and a drying oven for baking the work after passing through the setting zone.

[0004] In the drying oven where baking is carried out, a workpiece is used to prevent the formation of pinholes due to rapid volatilization of volatile components in the paint.
The temperature of the workpiece is raised slowly over a fairly long period of time, and then the workpiece is held in an atmosphere at a temperature of, for example, about 140 degrees Celsius for a predetermined period of time to perform baking.

JP-A-61-143684 discloses that in a drying oven where baking is performed, in the area where the temperature of the workpiece is raised, the temperature on the side closer to the drying oven inlet is lower than the temperature on the side far from the inlet. A method is disclosed in which the temperature is set low to prevent a rapid temperature rise of the workpiece.

[Problems to be Solved by the Invention] Recently, when painting a workpiece such as an automobile body, there has been a tendency for the types of required coating conditions, such as the types of paints used, to increase. As described above, when coating conditions vary, a single coating line cannot handle the situation, and it is necessary to prepare multiple coating lines. But then,
Providing a drying oven for each of the plurality of coating lines requires some kind of countermeasure in this respect, considering that the drying oven is large and expensive.

[0008] Accordingly, an object of the present invention is to provide a coating drying method that can perform coating appropriately in response to different required coating conditions while simplifying the drying oven as much as possible.

In order to achieve the above object, the present invention basically has the following configuration. In other words, there is a coating zone where paint is applied to the workpiece, and a coating zone.
a plurality of painting lines equipped with a pre-drying oven for preliminary drying of the paint applied in the process, and one main drying oven set as a common use for the plurality of coating lines, After selecting a necessary painting line from among the plurality of painting lines according to the painting conditions required for the workpiece and completing all paint application and pre-drying on the selected painting line. The main drying oven is configured such that the main drying oven is performed in the main drying oven.

[0012] In the present invention, since only one main drying oven for finally drying the paint is required for a plurality of painting lines, the drying oven for drying the paint to the final stage is required for each painting line. The drying furnace as a whole can be made simpler than when a furnace is provided. In addition, since the volatile matter in the paint has already been volatilized to a considerable extent by the time it passes through the pre-drying oven, this drying oven can quickly dry the workpiece to a specified level with little or no consideration of countermeasures such as pinhole formation. This is preferable in terms of shortening the length of the drying oven itself and suppressing installation costs.

[0013] Since the paint is pre-dried in advance on the painting line, it may be necessary to move the workpiece a considerable distance after leaving the painting line to reach the main drying oven. Since the coating is pre-dried in advance using a pre-drying oven, it is possible to reliably avoid the possibility that dust will adhere to the coated surface before it reaches the main drying oven.

[0014] Similarly, even when selecting a plurality of painting lines and proceeding with painting in sequence, the above-mentioned problems should be avoided before moving from one painting line to another. Moreover, when applying the paint for the second time, since the coated surface formed in the previous step has already been pre-dried, it is possible to perform multiple coats well.

As mentioned above, since problems such as dust adhesion to the painted surface are solved by pre-drying, there is a great deal of freedom in how to layout the multiple main drying ovens and multiple painting lines. It will be expensive. Preferred embodiments and advantages of the invention will become apparent from the following description of the examples.

Embodiments of the present invention will be described below with reference to the accompanying drawings. In Figure 1, A is the first painting area, B
is the second painting area, and C is the third painting area. The first painting area A has two painting lines CL1, the first and second painting lines.
, CL2 are formed. In the second painting area B, two third and fourth painting lines CL3 and CL4 are formed. In the third painting area C, two fifth and sixth painting lines CL5 and CL6 are formed.

Two painting lines C in painting area A
The upstream portions of L1 and CL2 are connected to each other at the branching portion X1, and the downstream portions thereof are connected to each other at the merging portion Y1. These portions X1 and Y1 are connected by a common line KL1.

The first painting line CL1 has a painting zone SP1, a setting zone, and a setting zone sequentially from its upstream side to its downstream side.
zone ST1 and pre-drying zone PB1. In the painting zone SP1, paint is applied to the workpiece W, for example, electrostatic painting is performed. In setting zone ST1,
Volatilization in the applied paint is evaporated, for example, in a low temperature atmosphere such as room temperature.

In the pre-drying zone PB1, the paint is pre-dried using, for example, a far-infrared or hot-air pre-drying oven. The drying temperature in this pre-drying oven is lower than the drying temperature in the main drying oven, which will be described later, and drying is carried out until the paint is cured to a state where it loses its viscosity. This prevents dust from adhering (viscous adhesion) to the coated surface after passing through the pre-drying zone PB1, and also prevents deterioration of the coated surface simply by applying an external force equivalent to the touch with a finger.

[0024] The second painting line CL2 is also the same as the first painting line C.
It is configured similarly to L1. Therefore, the reference numeral "2" is used instead of the reference numeral "1" for the same components as those in the first painting line CL1, thereby omitting the redundant explanation thereof. Further, the other painting areas B and C are configured in the same manner as the painting area A. Therefore, for the same component as the component in painting area A, "
By assigning the numeral ``3'', ``4'', ``5'', or ``6'' instead of the numeral ``1'', the repeated explanation will be omitted. However, in painting lines where water-based paint is used, the setting zone is a preheat zone.
It is said that

A common transport line ML is provided for each of the painting areas A, B, and C. For the common line KL1 of painting area A, workpiece transfer device J
1, the workpiece W is transferred to and from the transport line ML via J2. In other words, the work W from line ML
is transferred to the common line KL1 by the transfer device J1,
The workpiece W transferred to this common line KL is transferred to the branch section X1.
The paint is then flowed to the first painting line CL1 or the second painting line CL2. Workpieces W from each painting line CL1, CL2 flow through the common line KL from the confluence section Y1, and are again transferred to the transport line ML by the transfer device J2. The above also applies to the relationship between painting area B and transport line ML (the transfer devices are J3 and J4), and the relationship between painting area C and transport line ML (the transfer devices are J5 and J6) However, transfer devices J1, J2, J3, J4, and J
5 and J6.

One main drying furnace MB is provided in the downstream portion of the transfer line ML from the transfer devices J1 to J6. The main drying furnaces MB1 to MB3 are of a far-infrared type or a hot air type, but the main drying furnace may be a combination of a far-infrared type and a hot air type.

[0032] The work W from the transport line ML is coated in an appropriate number of coating lines from among the six coating lines CL1 to CL6 according to the coating conditions in the order according to the coating conditions. will be carried out. At this time, the main drying in the main drying oven MB is not performed until the pre-drying oven in the selected coating line at the final coating stage is completed.

An example of how the workpiece flows depending on the coating conditions for the workpiece W is shown in Table 1 below.

[0036]

[Table 1]

In Table 1, for both painting areas A and B, one of the two painting lines is used, and for painting area C, two painting lines L5 and SL6 are used. Of course, painting area A,
Works are transferred between multiple painting lines between B and C using the transport line ML and the common line KL (KL1 to KL1 to KL).
L3).

Next, selection of a coating line will be further explained using some typical coating conditions as examples. However, it is assumed that the undercoating for the work W has been completed. (1) When performing 4 coats of intermediate W (double) coats, the order is CL1 (first intermediate coat) → CL2 (second intermediate coat) → CL3 (top coat) → MB. (2) When performing 4 coats with overcoat CL1
The order is (intermediate coating) → CL3 (first top coat) → CL6 (second top coat) → MB. (3) When applying aqueous base coat (3 coats) CL
1 (intermediate coating) → CL3 (water-based paint) →, CL4 (
clear paint) → MB. (4) When using 2 base colors with 3 coats. CL1 (intermediate coating) → CL3 (solid paint) → CL4 (
Metallic) → MB. (5) When using two-tone color coding. CL1 (intermediate color) → CL3 (first color) → CL5 (second color)
color) → MB. Note that the painting conditions performed in one painting line may be always the same and the painting conditions may be changed only between painting lines, or the painting conditions may be changed in one painting line.

[Brief explanation of the drawing]

FIG. 1 is a simplified plan view showing one embodiment of the present invention.

[Explanation of symbols]

CL1-CL6 Painting line SP1-SP6 Painting zone PB1-PB6 Pre-drying zone (pre-drying oven) J1
~J6 Transfer device X1-X3 Branching section Y1-Y3 Merging section KL1-KL3 Common line ML Transport line MB Main drying zone (main drying oven)

Claims (4)

[Claims] 1. A plurality of painting lines each comprising a painting zone for applying paint to a workpiece and a pre-drying oven for preliminary drying the paint applied in the painting zone;
And one main drying oven is provided which is set as a common use for the plurality of painting lines, and among the plurality of painting lines, a necessary painting line is installed according to the painting conditions required for the workpiece. A method for drying a paint, characterized in that after all paint application and preliminary drying are completed in the selected painting line, the main drying oven is performed in the main drying oven. 2. In claim 1, there is provided one conveyance line connected to the main drying oven, and the selection of the painting line according to the required coating conditions is based on the selection of the plurality of painting lines and the conveyance line. Something that is done by giving and receiving work between people. 3. In claim 2, a position where workpieces are delivered and received between each of the painting lines and the conveyance line,
Those placed in series with the conveyance line. 4. The method according to claim 1, wherein a plurality of coating lines are selected according to the coating conditions.