JP2016007561A - Coating method of vehicle welded part and structure of vehicle welded part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating method of a vehicle welded part and a structure of the vehicle welded part which reliably prevents cracking of a lower layer due to a stress applied onto the welded part from attaining to a coated film and, thereby, can prevent the generation of rust of the welded part beforehand when the coated film is formed on the welded part formed by arc welding.SOLUTION: A soft chip primer layer 4 is formed on the surface of an undercoat coated film 3 on a welded part 2 formed by arc welding, a coated film 5 is formed on the soft chip primer layer, therefore, slag (oxidized film) can be enclosed by the soft chip primer layer 4 even when the slug is produced on the surface of the welded part 2 by the arc welding, a stress is applied onto the welded part 2, thereby, even when cracking occurs on a brittle slag, the cracking is absorbed by the soft chip primer 4 and the cracking can be reliably prevented from further attaining to the coated film 5 of an upper layer.

Description

  The present invention relates to a coating method for a vehicle welded portion and a vehicle welded portion structure for coating a welded portion formed by arc welding metal members constituting a vehicle.

  Conventionally, as shown in FIG. 2, in a vehicle 51 with a loading platform such as a truck having a loading platform 50 at the rear of the vehicle for transporting cargo, the loading platform 50 is provided with three shrouds called gates 52. Each of the gates 52 is attached to the cargo bed 50 by a plurality of hinges 53 so that the gate 52 can be raised and lowered, and is fixed in a state where the gates 52 are raised by the hooks 54 at the time of transportation. Falling is prevented, and when loading or unloading a load, one of the gates 52 is unfixed, the gate 52 is tilted downward, and a part of the enclosure of the loading platform 50 is removed (see Patent Document 1). ).

  At this time, the hinge 53 and the hook 54 are usually fixed by welding, and are painted after welding. The detailed structure of the welded portion is, for example, as shown in the cross-sectional view of FIG. That is, as shown in FIG. 3, a welded portion 56 is formed by arc welding a steel plate 55a which is a material of the hinge 53 and the hook 54 and a steel plate 55b which is a material of the gate 52 and the like to which the hinge is to be attached. Further, an undercoat film 57 is formed by electrodeposition coating for preventing rust, and an intermediate coat film 58a and an upper coat film 58b are sequentially formed.

No. 61-41313 (CD-ROM of Japanese Utility Model Publication No. 62-151186) (refer to page 2, column 3, line 23 to column 4, line 212 and FIGS. 2 to 6)

  However, a large stress is applied to the fixing portion of the hinge 53 and the hook 54 under the usage environment such as raising and lowering of the gate 52, and particularly when it is fixed by arc welding, a slag (oxide film) formed by arc welding. Since 58 is formed in the welded portion and the slag 58 is brittle, there is a problem that the slag 58 is cracked due to stress and reaches the coating, resulting in rust due to intrusion of rainwater from the outside. In order to solve such a problem, coating is performed after the slag 58 on the surface of the welded portion is removed by a grinder or the like. However, a new problem that causes an increase in work man-hours arises.

  In the present invention, when a coating film is formed on a welded part by arc welding, it is possible to reliably prevent cracks in the lower layer due to stress applied to the welded part from reaching the coating film and to prevent the occurrence of rust in the welded part. It aims to be able to prevent.

  In order to achieve the above-described object, a method for painting a vehicle welded portion according to the present invention is a method for painting a vehicle welded portion in which a welded portion formed by arc welding metal members constituting a vehicle is coated. It is characterized by comprising a step of applying a soft tip primer on the surface of the welded spot welded or the surface of the electrodeposition layer thereon, and a step of forming a coating film on the application surface of the soft tip primer ( Claim 1).

  Further, the vehicle welded portion structure of the present invention is a vehicle welded portion structure in which the metal members constituting the vehicle are arc welded and then painted, and the surface of the arc welded portion or the electrodeposited layer thereon is provided. A soft chip primer layer formed on the surface and a coating film formed on the soft chip primer layer are provided (claim 2).

  According to the first and second aspects of the present invention, arc welding is performed in order to form the soft tip primer layer on the surface of the arc welded portion or the surface of the electrodeposition layer thereon and to form the coating film thereon. The slag (oxide film) generated on the surface of the welded part can be covered with a soft tip primer layer, and even if a crack occurs in the brittle slag due to stress applied to the welded part, this crack has a soft elongation It can be absorbed by the soft tip primer layer and reliably prevent cracking of the upper layer coating film, preventing cracking of the coating film without removing slag and generating rust on the weld. It can be prevented in advance.

  The soft chip primer layer can be formed by spraying, for example, urethane or polyolefin, and can be formed by a simple process.

It is sectional drawing which shows the coating procedure of the vehicle welding part in one Embodiment of this invention. It is a perspective view of a general truck (vehicle with a loading platform). It is sectional drawing of the welding part in the track | truck of FIG.

  An embodiment of the present invention will be described in detail with reference to FIG. In the following description, FIG. 2 is also referred to.

  The present embodiment is an example in which the present invention is applied to a welded portion of a hinge 53 and a hook 54 in a loading platform 52 of a vehicle (truck) 51 with a loading platform shown in FIG. As shown in FIG. 1, the steel plate 1a that is the material (metal member) of the hinge 53 and the hook 54 and the steel plate 1b that is the material (metal member) of the gate 52 and the like to which this is to be attached are arc-welded. Then, the weld 2 is formed, and an undercoat film 3 is formed on the undercoat film 3 by electrodeposition coating for rust prevention, and a soft chip primer layer 4 is formed on the undercoat film 3 by, for example, spraying urethane, The intermediate coating film 5a and the top coating film 5b are sequentially laminated to form the coating film 5.

  At this time, in order to form the soft tip primer layer 4 on the surface of the welded portion 2 formed by arc welding and to form the coating film 5 thereon, a slag (oxide film) S is formed on the surface of the welded portion 2 by arc welding. Even when the slag S is generated, the slag S is encapsulated by the soft chip primer layer 4 so that the crack of the slag S caused by the stress can be absorbed by the soft chip primer layer 4 having a soft elongation.

  Therefore, according to the above-described embodiment, even when a crack is generated in the fragile slag S due to the stress applied to the welded portion 2, the crack can be absorbed by the soft soft tip primer layer 4, and further, It is possible to reliably prevent the coating film 5 from cracking, to prevent the welded portion 2 from being rusted, and to improve the reliability of the welded portion 2.

  Further, since the slag is covered by the soft chip primer layer 4 and the cracks of the slag S can be absorbed, it is not necessary to remove the slag and the work man-hour is not increased. Further, the soft chip primer layer 4 can be formed by spraying urethane or the like, for example, and can be formed by a simple process.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the case where the soft chip primer layer 4 is formed by spraying urethane has been described, but polyolefin may be used in addition to urethane.

  In the above-described embodiment, the soft tip primer layer 4 is formed on the undercoat film 3 by electrodeposition coating, but there is no undercoat film by electrodeposition coating, and the soft tip primer layer 4 is formed on the surface of the weld 2. Even if it is formed, the present invention can be carried out in the same manner, and the same effect as the above-described embodiment can be obtained.

  In the above-described embodiment, the case where the present invention is applied to the vehicle (truck) 51 with a loading platform has been described, but it goes without saying that the present invention can also be applied to a welded portion by arc welding of other vehicles.

DESCRIPTION OF SYMBOLS 1a, 1b ... Steel plate 2 ... Welded part 4 ... Soft tip primer layer 5 ... Coating film 5a ... Intermediate coating film 5b ... Top coating film

Claims (2)

In the coating method of the vehicle welded portion, which coats the welded portion formed by arc welding metal members constituting the vehicle,
Applying a soft tip primer to the surface of the arc welded portion or the electrodeposition layer thereon;
And a step of forming a coating film on the coated surface of the soft chip primer. In the vehicle welded part structure in which the metal members constituting the vehicle are arc welded and then painted,
A soft tip primer layer formed on the surface of the arc welded portion or the electrodeposition layer thereon,
A vehicle welded structure comprising: a coating film formed on the soft tip primer layer.

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