JP2003003270A - Posttreatment system in zinc plating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To selectively perform four stages generated from the presence of baking treatment, no presence thereof, hexavalent chromium film treatment, the presence of hexavalent chromium free film treatment and no presence thereof on one line. SOLUTION: The system is provided with a stage A where zinc plating and treatment annexed thereto are performed; a stage B where baking treatment is performed to a work subjected to the zinc plating stage A; a stage C where hexavalent chromium film treatment is performed to the work subjected to the zinc plating stage A; and a stage D where hexavalent chromium free film treatment is performed to the work subjected to the zinc plating stage A. Also, the stage A, the stage B and the stage D are contacted by a carrying means E, and four kinds of posttreatments generated from the presence of the baking treatment stage B, no presence thereof, the hexavalent chromium film treatment D, the presence of the hexavalent chromium free film treatment C and no presence thereof are practiced.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a post-treatment system for zinc plating capable of performing zinc plating, baking treatment, and hexavalent chromium film treatment. [0002] Zinc plating is widely used as an inexpensive and highly reliable surface treatment. Further, by applying hexavalent chromium film treatment on zinc plating, the appearance is beautiful and the corrosion resistance is remarkably improved. Can be enhanced. Further, hydrogen gas generated during plating and confined in the plating layer is treated by baking, but such matters are treated as points to be improved until recently. No. 131764, JP-A-5-78859
Can be seen in the invention of the issue. On the other hand, the problem of environmental pollution has become apparent, and the movement to eliminate hexavalent chromium contained in a rust preventive film applied on zinc plating has been clarified, and alternative treatment techniques for chromate have been developed. Rust-preventive coatings that do not contain hexavalent chromium include those using trivalent chromium, phosphorus / molybdate coatings, silane coatings, titanium coatings, etc. The problem remains in that it is difficult to change to 100% and it is impossible to find a technology that can be replaced by 100%. [0006] However, hexavalent chromium-free has not been completely implemented immediately, but has been partially implemented since 2003. If both hexavalent and trivalent chromate solutions are present,
There is no problem in entering a valent chromate solution, but conversely, a hexavalent chromate solution cannot enter a trivalent chromate solution. Therefore, there is a problem in adding a trivalent chromate treatment step to the current hexavalent chromate treatment line, and it is necessary to form a separate line for hexavalent chromate treatment and trivalent chromate treatment. SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object a baking treatment and a baking treatment pass, as well as a hexavalent chromium film treatment,
The present invention is characterized in that four steps generated depending on the presence or absence of hexavalent chromium-free film processing can be selectively performed on one line. SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a zinc plating, a step A of performing zinc plating and a process accompanying the zinc plating, and a work which has passed through the zinc plating step A. B for performing a baking process, a process C for performing a hexavalent chromium film treatment on the work having undergone the zinc plating process A, and a process D for performing a hexavalent chromium-free film treatment for the work having undergone the zinc plating process A And
In order to move the work, the process A, the process B, and the process D
1) baking treatment step B, hexavalent chromium coating treatment step C, 2) baking treatment step B, hexavalent chromium-free coating treatment step D, 3) baking treatment step B , A hexavalent chromium film processing step C, 4) a baking processing step B, and a hexavalent chromium-free film processing step D. [0007] A post-processing system according to the present invention comprises:
It is applied to zinc plating which can perform zinc plating, baking treatment and hexavalent chromium film treatment. Zinc plating can be defined as mainly attaching zinc to the surface of iron or steel, but the zinc plating step A includes pretreatment such as alkali degreasing, pickling, and water washing.
Usually, washing is performed after plating. In the zinc plating step A, since the hydrogen gas generated during plating remains in the plating layer without being escaped, baking is often performed to remove the hydrogen gas. For this purpose, a baking step B is provided in parallel with the galvanizing step. However, the baking step B may not be performed. The hexavalent chromium film processing step C is a step of performing hexavalent chromium film processing on the zinc-plated work through the zinc plating step A. The work has been galvanized, and a chromate film is formed thereon using a chromate compound or the like. Hexavalent chromium in the film is soluble, and even if the film is destroyed, hexavalent chromium reacts with zinc to exhibit a regenerating property that forms a chromate film again, and therefore cannot be compensated for by other alternative treatments. The point is as mentioned above. However, it is a common recognition that the strong oxidizing power of hexavalent chromium causes various harms to the human body, and a hexavalent chromium-free film treatment has been proposed as an alternative treatment. [0010] That is, in the hexavalent chromium-free film treatment step D, a film formation treatment without using hexavalent chromium is performed. Applicable hexavalent chromium-free coating treatments include treatment using trivalent chromium (including chromium only and those added with silicic acid, etc.), phosphorus / molybdate coating, silane coating, titanium coating, etc. Has already been mentioned. In the present invention, these hexavalent chromium-free film treatments can be applied. The zinc plating step A, the baking step B, and the hexavalent chromium coating step C are carried by a transport means E
And a situation where the work can be sequentially transported is prepared. Therefore, the above-described steps A, B, C and D are arranged in a predetermined arrangement so that the route and distance of the conveying means E are not complicated and long. [0012] The following four items are realized by such a processing apparatus as a whole.
Various steps can be performed. 1) Baking treatment step B, hexavalent chromium coating treatment step C, 2) Baking treatment step B, hexavalent chromium free coating treatment step D, 3) Baking treatment step B pass, hexavalent chromium coating treatment step C, 4 B) Baking treatment process B pass, hexavalent chromium-free film treatment process D. In the above, the baking process step B pass means not passing (passing) the baking process step B. The conveying means E includes a zinc plating step A, a baking step B, and a hexavalent chromium-free coating step D.
Contact The hexavalent chromium film processing step C is arranged at a position deviated from the transporting means E, so that the work that has gone through the galvanizing step A and the baking processing step B is not brought directly through the transporting means E. It is set. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail with reference to the illustrated embodiments. FIG. 1 shows an entire apparatus for performing a zinc plating process using a barrel and a post-processing process according to the present invention, and includes a zinc plating process A, a baking process B, and a hexavalent chromium coating process. C, a transporting means E which communicates a hexavalent chromium-free coating treatment step D, a zinc plating step A, a baking step B, and a hexavalent chromium-free treatment step D. The galvanizing step A has a circling line indicated by A-A ', and the starting end and the ending are extremely close to the conveying means E so that the work can be transferred. The zinc plating step A includes process elements such as alkali degreasing 11, pickling 12, acid electrolysis 13, electrolytic degreasing 14, activation 15, galvanizing 16, and the like. Provided. The baking process B has a line indicated by BB ', which is arranged in parallel with the zinc plating process AA' of the elongated peripheral line. The baking process B is disposed very close to the transporting means E so that the work can be delivered at the start end. The baking treatment step B includes a dehydrator 21, a barrel stacker 22, a baking furnace 23, and a necessary rinsing section 24. At the rear end, the barrel-containing work transfer means e1, which is referred to as "separation", is next to the baking furnace B1. Contact the next line. The transfer means e1 for barrel-containing work includes lifters 25 and 26 (elevators) provided on each line, and a transport section 27 for connecting both lifters. A hexavalent chromium-free coating processing step D is provided on the line following the baking processing step B, with the starting end located very close to the conveying means E. By arranging the hexavalent chromium-free film treatment step D before the hexavalent chromium film treatment step C, the hexavalent chromate liquid is not mixed into the trivalent chromate liquid. This connecting line is provided with the above-mentioned barrel so that the hexavalent chromium-free film processing step D can be directly connected to the zinc plating step A through the conveying means E and can be connected to the baking step B from the terminal side. It is connected to the work transfer means e1. The hexavalent chromium-free coating treatment step D comprises the steps of:
The treatment line is divided into a treatment line indicated by D 'and a pickling line indicated by D'-D ". The treatment line includes a pickling treatment 31 with nitric acid or the like, a rinse 32, and a hexavalent chromium free coating treatment 33. And a necessary washing section 34. The pickling line is provided with a cooling section 35, an acid washing 36 with nitric acid, etc., and a necessary washing section 37. Further, in the hexavalent chromium-free film processing step D, Transfer means e2, e3, e4 for transferring the work containing the barrel, moving the barrel, etc. are provided at a total of three places before and after the starting line and the processing line, respectively. In each of the lines G, G, the work is moved by the transfer means provided in each line, and the transfer means e3 converts the work having undergone the hexavalent chromium-free film treatment step D into a hexavalent chromium-free film treatment 33.
It is provided for transferring to a subsequent drying step G. The drying step G includes a dehydrator 41, and further includes a finished product unloader 42 and an empty can return unit 43. As the transfer means e2, for example, a conveyor for returning a car between the lines G and D is appropriate. These transfer units e1, e2, e3, and e4 may be treated as having the same purpose as the transfer unit E in that they have a purpose of carrying a work. Convey means,
Conveyors are used for the transfer means, and various types are used according to differences in installation locations, transport, and transfer modes. The line of the hexavalent chromium film processing step C is 6
It is provided in parallel outside the line of the valent chromium-free film processing step D. Hexavalent chromium coating process C is C-
It has a processing line indicated by C '. The work is connected to the front line (D) by the transfer means e4,
Wash, black, rinse, wash, green, wash, wash, yellow,
Hexavalent chromium film processing unit 5 consisting of water washing, water washing, white color, etc.
1 and a dehydrator 52, and further includes a finished product unloader 53 and an empty can return unit 54. In the present invention having such an apparatus configuration, the four types of presence / absence of a baking step and presence / absence of a hexavalent chromium film treatment step will be described for each case. In the galvanizing step A, the work that has been subjected to the pretreatment and the galvanizing step is replaced with a basket for processing at the intersection of the A-E line. 1) In the case of the baking treatment step B and the hexavalent chromium film treatment C, the work is transported from the intersection of the A-E line to the intersection of the BE line, carried by the treatment basket and the carrier, and washed with water during that time. Dehydration and drying, stacking, continuous baking with a continuous baking furnace, and step-separation are performed. Transfer means e
1. Cooled while moving from the end of the D ″ line toward D ′, and subjected to water washing, nitric acid washing, and water washing. In the transfer means e4, the work is transferred to a basket dedicated to hexavalent chromium film processing (empty basket). Is returned to the intersection of the DE line by a cart.) The carriage of e4 is transferred to the intersection of C-e4 and 6
Hexavalent chromium film processing is performed in the chromium (VI) film processing step C, and after the processing, the work is opened in the container by the reversing machine in the line CC ′ and the process is completed. The empty basket is returned to the line e4 and waits at the process D side. 2) In the case of the baking treatment step B and the hexavalent chromium-free film treatment step D, the work is transported from the intersection of the A-E line to the intersection of the BE line, and is continuously carried out in the same manner as in 1). After being baked in a baking furnace, it further moves via a transfer means e1 while being cooled from the end of D ″ toward D ′, and after being washed with water, nitric acid and water, undergoes a hexavalent chromium-free film treatment. After processing, transfer means e3 and line D
The work is placed on the processing basket at the intersection with the above, and transported to the Ge-e3 intersection by the transfer means e3. The work is dehydrated and dried in the G line, the work is easily opened by the reversing machine, and the process is completed. 3) In the case of the baking treatment process B pass and the hexavalent chromium film treatment process C, the work is moved to the intersection of the DE line by the transport means E, transported by the carrier together with the processing basket, and washed with nitric acid and water. Then, the processing basket is inverted at the intersection of De-e4, and the work is transferred to a basket dedicated to hexavalent chromium film processing (the empty basket is returned to the position of D by a cart). It is transferred to the intersection of Ce4 by the carriage of the transfer means e4, hexavalent chromium film processing is performed on the line C, and after the processing, the work is opened in the container by the reversing machine of the line CC 'and the process is completed. After that, it is the same as 1). 4) In the case of the baking process B pass and the hexavalent chromium-free film processing process D, the workpiece is moved to the intersection of the DE line by the transport means E, carried by the carrier together with the processing basket, washed with nitric acid, washed with water, After each process of hexavalent chromium-free film treatment, water washing, water washing, and rinsing, it is transferred to the moving means e3, and G-e3
It is transported to the intersection. In the line G, the work is easily opened by dehydration and drying and a reversing machine, and the process is completed. Since the present invention is constructed and operates as described above, it is generated by the hexavalent chromium film treatment and the hexavalent chromium free film treatment, and the presence or absence of the baking treatment and the baking treatment pass. The four steps can be selectively performed on one line, and it is suitable for realizing hexavalent chromium-free while maintaining the hexavalent chromium film processing step within an allowable range. Since there is no danger of the liquid being mixed into the hexavalent chromium-free side, remarkable effects are exhibited, such as high safety and improvement in capital investment effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing an embodiment of a post-processing system for galvanizing according to the present invention.

Claims (1)

Claims: 1. A step A in which zinc plating and baking treatment and hexavalent chromium film treatment can be performed, wherein zinc plating and a treatment accompanying the zinc plating are performed;
Step B of performing a baking treatment on the work that has passed through the zinc plating step A, Step C of performing a hexavalent chromium film treatment on the work that has passed through the zinc plating step A, and 6 A process D for performing a chromium-free coating process, and the process A, the process B, and the process D are communicated by the transport means E for the movement of the work, and 1) a baking process B and a hexavalent process. Chromium coating process C, 2) Baking process B, hexavalent chromium-free coating process D, 3) Baking process B pass, hexavalent chromium coating process C, 4) Baking process B pass, hexavalent chromium A post-treatment system for zinc plating, wherein four types of post-treatments of a free film treatment step D are executable.