JPH02174971A - Painting method - Google Patents

Abstract

PURPOSE:To prevent defective painting by decreasing a paint discharge rate to the rate at which a prescribed coated film thickness is attained during the time after the point of the time when a painting machine moving back and forth in the direction orthogonal with a transporting path approaches an inverting position and begins to decelerate before the machine is inverted again and restores the initial speed. CONSTITUTION:The painting machine 1 is mounted to a slider 4 which is moved back and forth by an endless chain 3 put on sprockets 2A, 2B and a work W is coated in forward and backward moving directions by the forward and backward movements of the machine. The moving speed of the painting machine 1 attains the specified speed in the distance (x) between the central lines x1 and x2 of the sprockets 2A, 2B and is once decelerated and is then increased to the initial speed between the inverting positions y1 and y2 of the sprockets 2A, 2B. Limit switches S1, S2 are disposed at the inversion starting point of the painting machine 1. The point of the time when the inversion starts and the point of the time when the inversion ends are detected by these switches. The flow rate of the paint between these points is controlled by the signal output to a flow rate control valve 7 and is decreased to a prescribed flow rate. The specified thickness of the coated film on the work W is thus obtd.

Description

[Detailed description of the invention] [Industrial application field].

The present invention relates to a coating method in which a coating machine is reciprocated in a direction perpendicular to a conveyance path of an object to be coated.

[Prior art]

When painting an object to be coated that has a fixed coating width, such as the body of an automatic tank or rolled steel plate, the object to be coated is transported at a constant speed, and one or a designated Generally, a reciprocating coating method is used, in which a plurality of spray machines installed at intervals are reciprocated and the coating is performed while spraying a constant amount of paint.

As a means for reciprocating the paint sprayer, for example, an engaging element is attached to an endless chain that is passed between two sprockets arranged at an interval approximately equal to the painting width and is driven to travel in one direction. A coating machine is mounted on a slider that is reciprocated through a slider.
(see publication).

Also known is a system in which a crank mechanism is used to convert rotational motion into reciprocating linear motion, and a coating machine is attached to this linearly moving part (slider).
(See Publication No. 1).

[Problem that the invention attempts to solve]

By the way, sprockets 2A and 2B as shown in FIG.
In a reciprocating coating device using a chain 3, the slider 4 moves linearly in the vertical direction by the action of the engager 5 attached to the chain 3 by rotating the sprockets 2A and 2B at a constant rate. Speed 2v is horizontal &% passing through the center of sprockets 2A and 2B
With H, , H2 as the border, it changes as shown in FIG. 2.

In other words, it moves up and down at a constant speed in the region X between the horizontal lines 1 (, , H), but gradually decelerates in the regions Y and Y2 closer to the inversion position from the horizontal vAni, Hz, and at the inversion position. It instantaneously becomes 0, then is reversed and accelerated, and then returns to its original constant speed, which is repeated.

Therefore, in areas Y and Y2, slider 4
Even if a fixed amount of paint is discharged from the paint sprayer 1 attached to the paint, a uniform paint film cannot be obtained.

Therefore, these areas Yl and Y2 were unavoidably considered to be play areas that were not to be painted.

Therefore, when designing and manufacturing a reciprocating coating device, it is necessary to set the area X to be higher than the height or axis of the object W to be coated, which causes the problem that the device becomes larger and heavier.

On the other hand, in a reciprocating coating device using a crank mechanism 10 as shown in Fig. 3, the linear speed V' is constantly changing as shown in Fig. 4, so the influence of speed changes is avoided. This is more serious than reciprocating painting equipment that uses sprockets and chains.

In particular, when reciprocally painting the surface of an automobile body W'' using a plurality of bell-shaped electrostatic atomizers IA and IB installed at predetermined intervals, thick coating is applied in the overlapped areas P between each atomizer. As a result, there is a risk that coating defects such as poor drying and poor coating film smoothness may occur, and countermeasures are urgently needed.

Therefore, the present invention provides a method for painting by reciprocating the paint sprayer while continuously discharging paint, even if the reciprocating speed of the paint sprayer changes near the reversal position, regardless of the speed change. The objective is to form a uniform coating film on the object to be painted.

[Means to solve the problem]

In order to solve this problem, the present invention provides a coating method in which the coating machine is reciprocated in a direction perpendicular to the conveyance path of the object to be coated, and when the coating machine approaches the reversal position, it begins to decelerate. The present invention is characterized in that the discharge amount of the sprayer is temporarily reduced to an amount that allows a predetermined coating thickness to be obtained from the time when the sprayer is reversed and returns to the predetermined speed again.

(Operation) When the sprayer approaches the reversal position, the speed of the sprayer begins to gradually decelerate, instantaneously reaches 0 at the reversal position, and then begins to accelerate in the opposite direction, returning to the predetermined speed again. .

Therefore, near the reversal position, the paint sprayer is moving at an extremely slow speed compared to the normal speed, so if a fixed amount of paint is supplied from the paint sprayer, a thick coating will be produced, but in the method of the present invention, the spray paint During the reversal, the amount of paint discharged is temporarily reduced, so a coating film with a uniform thickness can be obtained without thick coating at both ends of the coating width. Painting defects due to poor drying or poor smoothness do not occur.

[Example ■]

The method of the present invention will be explained below based on 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 film thickness.

In the figure, 1 is a coating machine that is driven back and forth while continuously discharging coating materials such as paint or lubricant, and is applied to two subtubes L7 2A and 2B that are arranged above and below at an interval of the painting width. It is attached to a slider 4 that is reciprocated by an endless chain 3 that is hung in parallel.

The slider 4 is engaged with an engaging element 5 attached to the endless chain 3 through an elongated hole 4a, and is configured to reciprocate up and down as the retainer 5 travels.

In this case, when the retainer 2B is rotated at a constant rotational speed (angular velocity ω) and the engager 5 is moved, the vertical movement speed of the retainer 5 is a constant speed in the area X. (V=rω), and the area Y+ and yz
At this point, the speed is decelerated until it reaches the reversal position, and at the reversal position, the speed momentarily becomes O, and then the speed is reversed and accelerated to return to the original speed. The slider 4 and the paint sprayer 1 attached thereto are moved up and down at a speed of V=rωX CO3θ until the slider 4 moves up and down. .

Sl and S2 are limit switches that detect the time when the sprayer 1 starts to decelerate (the time when the reversal starts) and the time when the sprayer 1 reverses, accelerates, and returns to a predetermined speed (the time when the reversal ends). , are provided at the point where the coating machine 1 starts decelerating, that is, at the height of the horizontal line X and x2.

6 determines the position of the coating machine 1 based on the detection signals of the limit switches SL and S2, and depending on the position,
It is a control device that adjusts the paint flow rate control valve 7, and controls the amount of coating ml from when the coating machine 1 starts reversing to when it ends reversing.
A predetermined control signal is output to the flow rate control valve 7 that adjusts the flow rate of paint supplied to the paint flow rate to reduce the paint flow rate.

The amount of decrease in the paint flow rate is determined according to the paint film thickness tX in area X when a fixed amount of paint is supplied, the paint film thickness 1V in areas Y1 and Yz, and the speed change of the coating machine. .

In a normal case, if the coating film thickness tV in the regions Y and Yz is maximum at the inversion position, and is, for example, 1.7 times the coating film thickness t8 in the region X, then the paint supply amount in the regions Y and Yz For example, M is determined by equation (1) and set in the control device 6.

M=MoX(1,70,7stn θ)/1.7
Mo = Paint supply amount θ in area X: Sprocket 2A from the start of reversal.

Rotation angle of 2B According to this formula, the paint supply amount in areas Y1 and Yz is gradually decreased from the start of reversal (θ-0'), and when it reaches the reversal position (θ-90''), it becomes The flow rate of the supplied paint is reduced to 1/17, and after being turned over at the reversal position,
It is accelerated and gradually increased until it reaches the end of inversion (θ-180'), and returns to the original supply ff1M at the end of inversion.

Note that the coating film thickness in each region X, Y, , Y, may be determined in advance experimentally or by simulation calculation.

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

When painting with this coating device, first, in area If supplied, the coating film thickness will be constant.

When the coating machine 1 descends or ascends and reaches the horizontal line X or x2 and enters the areas Y and Yz, a detection signal is output to the control device 6 through the limit switches S1 and s2. , the flow rate control valve 7 is throttled and reduced according to a preset paint supply rate.

Therefore, if the discharge amount was constant, thick coating would occur near the reversal position in areas Y and Yz, but according to the method of the present invention, the discharge amount is reduced, and as shown by the solid line in FIG. Since it is possible to paint with a coating thickness equal to area There is no possibility of paint defects due to defects.

[Example ■]

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

When the paint sprayers IA and IB are reciprocated by the crank mechanism 10, their linear speeds are constantly changing.
It is difficult to determine when the reversal starts and when the reversal ends.

Therefore, in this case, the limit speed v0 that causes thick coating in the vicinity of the reversal position is determined experimentally or numerically in advance, and that speed is used as the reference speed, and the time when the speed is decelerated below the reference speed is the time at which reversal starts. , the time when the coating machines IA and IB are reversed, accelerated, and reach the reference speed may be determined as the time when the reversal ends.

Furthermore, the present invention is not limited to the position detection beams SI and S2 of the paint sprayers IA and IB, and any position detection sensor or any position detection means may be employed.

In particular, in the case of a crank mechanism, the position and speed of the atomizers IA and IB can be detected from the rotational speed and angle of rotation of the drive shaft of the crank, so they can be detected at a distance from the atomizer 1.

Furthermore, the amount of paint discharged is not limited to the case where the flow rate control valve is used to control the amount of paint, but any other arbitrary means can be adopted such as when the rotational speed of the pressure pump 8 is variably controlled as in this example.

Furthermore, in the above embodiment, a case has been described in which the paint supply amount is variably controlled in accordance with changes in the speed of the coating machine, but it may also be reduced by a constant amount from the start of reversal to the end of reversal. .

(Effects of the Invention) As described above, according to the present invention, the amount of paint discharged is reduced from when the paint sprayer approaches the reversal position and is decelerated until it is reversed and returns to a predetermined speed. It is possible to form a coating film with a constant thickness over the entire area that can be coated with a reciprocating coating machine, thereby preventing coating defects due to poor drying or poor smoothness. It has the excellent effect of being able to

[Brief explanation of the drawing]

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 changes in speed of the coating machine, Fig. 3 is a flow sheet showing another embodiment, and Fig. 4 is the coating machine. It is a graph showing the speed change of . Explanation of symbols 1, LA, IB--painting machine, 2A, 2B-sprocket, 3--chain, 4-slider, SL, S2 limit switch, 6-control device, 7-flow control No. 1 Fig. 2 Fig. 4 figure

Claims (1)

[Claims] In a coating method in which the coating machine is reciprocated in a direction perpendicular to the conveyance path of the object to be coated, when the coating machine approaches the reversal position and begins to decelerate, the coating machine reverses and restarts. A coating method characterized in that the discharge amount of the coating machine is temporarily reduced to an amount that allows a predetermined coating thickness to be obtained until the speed returns to a predetermined speed.