JP2531769B2 - Painting method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a coating method in which a coating machine is reciprocated in a direction orthogonal to a transport path of an object to be coated.

[Prior art]

When painting on an object to be coated that has a constant coating width, such as an automobile body or rolled steel sheet, the object to be coated is transported at a constant speed and one unit or at a predetermined interval in the direction orthogonal to the transport direction. Generally, a reciprocating coating method is used in which a plurality of coating machines provided in 1 are reciprocally moved to spray the coating material at a constant discharge amount.

As a means for reciprocating the coating machine, for example, an engaging element is attached to an endless chain that is run between two sprockets arranged at intervals substantially equal to the coating width and is driven in one direction. It is known that a slider is reciprocated through a coating machine attached to a slider (see JP-A-56-136675 and JP-A-63-41088).

It is also known that a rotary motion is converted into a reciprocating linear motion by using a crank mechanism, and a coating machine is attached to the linear motion portion (slider) (see JP-A-62-45371).

[Problems to be Solved by the Invention]

By the way, in the reciprocating coating apparatus using the sprockets 2A, 2B and the chain 3 as shown in FIG. 1, the slider 4 is moved up and down by the action of the engaging element 5 attached to the chain 3 by rotating the sprockets 2A, 2B at a constant speed. Although it reciprocates linearly in the direction, the vertical velocity V in the vertical direction
Changes with respect to horizontal lines X ₁ and X ₂ passing through the centers of the sprockets 2A and 2B as shown in FIG.

That is, the region X sandwiched between the horizontal lines X ₁ and X ₂ moves up and down at a constant speed, but the regions Y ₁ and Y ₂ closer to the reversal position from the horizontal lines X ₁ and X ₂ are gradually decelerated to cause the reversal. At the position, it becomes 0 instantaneously, then reverse acceleration is performed, and it returns to the original constant speed again.

Accordingly, in the region Y ₁ and Y _2, since the coating material from the coating machine 1 mounted on the slider 4 can not be obtained a uniform coating film even by dispensing, Eze and these regions Y ₁ and ceased Y ₂ was considered a play area without painting.

Therefore, when designing and manufacturing a reciprocating coating device,
It is necessary to set the region X to be equal to or higher than the height or width of the object W to be coated, which causes a problem that the device becomes large and the weight increases.

On the other hand, in the reciprocating coating apparatus using the crank mechanism 10 as shown in FIG. 3, the linear velocity V '
Since it constantly changes as shown in FIG. 4, the influence of speed change cannot be avoided, and is more serious than the reciprocating coating device using a sprocket and a chain.

In particular, when reciprocating the surface of the automobile body W'using a plurality of bell-type electrostatic coating machines 1A and 1B provided at predetermined intervals, a thick coating is applied at the coating overlap portion P between the coating machines. There is a possibility that a state may occur and a coating failure such as poor drying or poor coating smoothness may occur, and countermeasures against it have been urgently requested.

Therefore, the present invention, when performing coating by reciprocating the coating machine while continuously discharging the coating material, near the inversion position,
Even if the reciprocating speed of the coating machine changes, it is an object to form a uniform coating film on the object to be coated regardless of the change in speed.

[Means for solving the problem]

In order to solve this problem, the present invention is a coating method in which a coating machine is reciprocated in a direction orthogonal to a conveyance path of an object to be coated, and the coating machine approaches a reversal position and starts decelerating. It is characterized in that the discharge amount of the coating machine is temporarily reduced to an amount at which a predetermined coating film thickness is obtained from the point of time when the coating machine is reversed and returns to the predetermined speed again.

[Action]

As the applicator approaches the reversal position, the applicator speed gradually begins to decelerate to a momentary zero at the reversal position, this time accelerating in the opposite direction and back to the predetermined speed.

Therefore, in the vicinity of the reversal position, the coating machine is moving at an extremely slow speed as compared with the normal speed, so if a large amount of a constant amount is supplied from the coating machine, thick coating is performed during that time. Since the discharge amount of the paint is temporarily reduced during the reversal, it is possible to obtain a coating film with a uniform coating thickness without thick coating on both ends of the coating width, and to dry it. No coating defects due to defects or poor smoothness will occur.

[Example I]

The method of the present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 1 is a block diagram showing a coating apparatus to which the method of the present invention is applied, and FIG. 2 is a graph showing the relationship between the position of the coating machine and the coating thickness.

In the figure, 1 is an applicator that is reciprocally driven while continuously ejecting a coating material such as a paint or an oil coating agent. It is parallelly hung on two sprockets 2A and 2B arranged vertically at a coating width interval. It is attached to a slider 4 which is reciprocally moved by an endless chain 3 which is formed.

The slider 4 is engaged with the engaging element 5 attached to the endless chain 3 through the long hole 4a, and is reciprocated up and down as the engaging element travels.

In this case, when the sprocket 2B is rotationally driven at a constant rotational speed (angular velocity ω) and the engaging element 5 is run, the vertical moving speed of the engaging element 5 is constant in the area X (V = rω), and in the regions Y ₁ and Y ₂ are decelerated until reaching the reversal position, momentarily become 0 at the reversal position, and then reversal acceleration is performed to return to the original speed V = rω × The slider 4 and the coating machine 1 attached thereto are reciprocated up and down by being moved at a speed of cos θ.

S ₁ and S ₂ are limit switches that detect when the coating machine 1 starts decelerating (starting reversal) and when the coating machine 1 reverses and accelerates to return to a predetermined speed (end of reversal). Therefore, it is provided at the point where the coating machine 1 starts deceleration, that is, at the height of the horizontal lines x ₁ and x ₂ .

Reference numeral 6 denotes a control device that determines the position of the coating machine 1 based on the detection signals of the limit switches S ₁ and S ₂ and adjusts the paint flow control valve 7 according to the position.
During the period from the start of the reversing to the end of the reversing, a predetermined control signal is output to the flow rate control valve 7 that adjusts the flow rate of the paint supplied to the coating machine 1 to reduce the flow rate of the paint.

Incidentally, the amount of decrease in the paint flow, the coating thickness t _X in the region X in the case of dispensing the coating material, and the coating thickness t _Y in the region Y ₁ and Y _2, according to the speed variation of the coating machine 1 Will be decided.

In the normal case, the coating thickness t _Y in the regions Y ₁ and Y ₂ is maximum at the inversion position, and for example, the coating thickness t _{X in} the region X is
If it is 1.7 times, the paint supply amount M in the regions Y ₁ and Y ₂ is determined by, for example, the formula (1) and set in the control device 6.

M = M ₀ × (1.7−0.7sin θ) /1.7 M ₀ : Paint supply amount in region X θ: Rotation angle of sprockets 2A and 2B from the start of reversal According to this formula, paint in regions Y ₁ and Y ₂ When the supply amount is gradually reduced from the start of reversal (θ = 0 °) and reaches the opposite position (θ = 90 °), it is reduced to 1 / 1.7 of the flow rate of the paint supplied in the area X, and the reversal position After reversing, it is accelerated and gradually increased until the end of reversal (θ = 180 °), and at the end of reversal, the basic supply amount M ₀ is restored.

The coating film thickness in each of the regions X, Y ₁ and Y ₂ may be obtained in advance experimentally or by simulation calculation.

In addition, the control of the paint supply amount M is not limited to the above-described calculation formula, but may be based on the numerical values and experimental formulas obtained experimentally and numerically so as to obtain a uniform coating film thickness. It may be.

And when painting with this painting device, first,
In the region X, while the coater 1 is traveling in the region X, the coater 1 is traveling at a constant speed, so that if the coating material is supplied to the coater in a fixed amount, the coating film thickness is also constant.

Then, coating machine 1 is lowered or elevated, reaching the horizontal line x ₁ or x _2, enters the region Y ₁ and Y _2, the control device 6 to the detection signal outputs the limit switch S ₁ and S ₂ As a result, the flow control valve 7 is throttled, and the flow rate is reduced according to the preset paint supply amount.

Therefore, if the discharge amount is constant, thick coating is produced in the vicinity of the inversion position in the regions Y ₁ and Y ₂ , but the discharge amount is reduced by the method of the present invention, as shown by the solid line in FIG. Since the coating film can be applied with the same coating thickness as that of the area X, the entire area of the areas X, Y ₁ and Y ₂ can be used for the coating, and the entire coating apparatus can be downsized, and at the same time, poor drying,
No coating failure due to poor smoothness will occur.

Example II

3 and 4 show the method of the present invention applied to a reciprocating coating device using a crank mechanism as a drive source.

When the coating machines 1A and 1B are reciprocally moved by the crank mechanism 10, the linear velocity thereof is constantly changing, so that it is difficult to determine the reversal start time point and the reversal end time point.

Therefore, in this case, the limit speed v ₀ that causes thick coating in the vicinity of the reversal position is experimentally or numerically determined in advance, and the speed is set as the reference speed, and the reversal start is started at the time when the speed is reduced to the reference speed or less. At the time, the time when the coating machines 1A and 1B are reversed and accelerated to reach the reference speed may be set as the end time of the reversal.

Also, limit switches are used to detect the position of coating machines 1A and 1B.
Not limited to S ₁ and S ₂ , any position detection sensor,
Arbitrary position detection means can be adopted.

In particular, in the case of using the crank mechanism, the position and speed of the coating machines 1A and 1B can be detected from the rotation speed and the rotation angle of the drive shaft of the crank, so that the position can be detected at a position away from the coating machine 1.

Further, the discharge amount of the paint is not limited to the case where the flow rate control valve is used for control, and any other means such as the case where the rotation speed of the pressure feed pump 8 is variably controlled as in this example can be adopted.

Furthermore, in the above-described embodiment, the case where the paint supply amount is variably controlled according to the speed change of the coating machine has been described, but it may be a case where the amount is decreased by a constant amount from the reversal start time to the reversal end time. .

〔The invention's effect〕

As described above, according to the present invention, the amount of paint discharged is reduced from the time the coating machine approaches the reversal position and is decelerated until the time it is reversed and returns to the predetermined speed. Since it is possible to form a coating film having a constant film thickness over the entire range that can be coated by a reciprocating coating machine, it is possible to prevent coating defects due to poor drying and poor smoothness. .

[Brief description of drawings]

FIG. 1 is a flow sheet showing a coating apparatus to which the method of the present invention is applied, FIG. 2 is a graph showing speed change of the coating machine, FIG. 3 is a flow sheet showing another embodiment, and FIG. 4 is the coating machine. 5 is a graph showing the speed change of the. Explanation of symbols 1,1A, 1B …… Coating machine, 2A, 2B …… Sprocket, 3 …… Chain, 4 …… Slider, S ₁ , S ₂ …… Limit switch, 6 …… Control device, 7 …… Flow rate Control valve.

Claims (1)

(57) [Claims] 1. A coating method for performing coating by reciprocating a coating machine in a direction orthogonal to a conveyance path of an object to be coated,
From the time when the coating machine approaches the reversing position and starts decelerating until the coating machine reverses and returns to the predetermined speed again, the discharge amount of the coating machine to the amount that can obtain the predetermined coating film thickness. A coating method characterized by a temporary reduction.