Research and Application of Camouflage Pattern Painting Process

LIU Ming-xing1, HU Zhang-zhi2, TIAN Zheng-qiao1
(1. Wuhan Hankou Machine Tool Factory, Wuhan 430050, Hubei, China; 2. First Design and Research Institute MI China Co., Ltd., Hefei 230601, Anhui, China)

Abstract: In order to improve the painting quality of deformation camouflage and digital camouflage patterns, this paper studies the camouflage pattern painting process including the selection of template materials, the making of templates, the pasting of the templates, the painting of camouflage patterns, etc.

0 Introduction
Modern In war, camouflage is an important part of operational support. Correct implementation of camouflage can not only conceal combat intentions and achieve the suddenness of combat operations, but also reduce the enemy’s killing rate of weapons, reduce damage to its own personnel, fortifications, and weapons, improve the survivability of the army, and fight for initiative on the battlefield. .
Camouflage camouflage, as an important means of concealing the truth of soldiers, has become one of the camouflage techniques developed by various countries. The development and application of traditional deformed camouflage has experienced nearly a century since World War II, and has played a huge role in protecting military bases and important strategic objectives. Traditional deformed camouflage is mainly composed of spots or stripes, with large spots, smooth edges, and strong visual discrimination. It is suitable for combating near-range, low-resolution optical reconnaissance and near-infrared reconnaissance. The detection methods of modern warfare present an important trend of multi-dimensional, intelligent, and fine-grained resolution capabilities. The ability to extract specific “graphics” from the “background” is getting stronger and stronger, and the traditional deformed camouflage camouflage has been difficult to deal with high-resolution aviation. And satellite imaging reconnaissance.

Digital camouflage is very different from traditional anamorphic camouflage. It uses the imaging principle of pixel lattice and the characteristics of human visual perception. The digital “dot matrix” makes the camouflage pattern overlap irregularly, and the edges between different colors are blurred and broken. It is very easy to simulate the natural background. In realistic jungle or desert conditions, the irregular contours of leaves, gravel, or fine sand exactly match the characteristics of the digital dot matrix, which easily creates an “optical illusion” for the observer, allowing the observer to extract from the “background” The special “graphics” are extremely difficult, thus achieving a good deformation and camouflage effect, which can effectively deal with high-resolution aerospace and aerospace optical reconnaissance.
Due to the excellent characteristics of digital camouflage, digital camouflage has gradually begun to replace traditional deformed camouflage. During the painting process of camouflage camouflage patterns, improve the clarity of the camouflage pattern, ensure that the camouflage pattern after painting is consistent with the design drawing, and ensure the quality of the coating film (no sagging, underbite, whitening, missing coating, Defects such as color mispainting), effectively reducing the self-repair rate, reducing the production cost during the production of camouflage templates, and increasing the repeated utilization of templates are the issues that engineering and technical personnel are most concerned about.

1 Deformation camouflage pattern spraying method
1.1 Deformation camouflage pattern spraying method
According to the requirements of design drawings, outline the car body with chalk and mark the color distribution (see Figure 1); then use color separation tape to paste along the outline of the chalk (see Figure 2); then spray the entire pattern. The tri-color camouflage of some vehicle bodies is not sprayed with the template method, because the surface area of ​​the car body is large, and there are more convex and concave surfaces. The camouflage patches of the tri-color camouflage have a large area and irregular shapes. Unable to cover the surface of the car body.

Fig. 1 Traditional Method of Painting Camouflage Patterns on Vehicles
Fig. 2 Traditional Method of Pasting Camouflage Patterns on Vehicles

1.2 Spraying method of
tarpaulin deformation camouflage The spraying of tarpaulin deformation camouflage uses transparent PVC soft glass rubber sheet (as shown in Figures 3 and 4) combined with horse dung paper to make a template. The template is positioned at the corresponding position on the tarpaulin for spraying according to the design requirements of the drawing. Compared with the traditional manual drawing method, using the template method for the camouflage camouflage spraying on the poncho not only reduces the labor intensity of the operator, but also improves the labor efficiency, ensures the production progress, and improves the consistency, clarity and quality of the camouflage pattern. , Saving raw materials and reducing production costs. Although there is a certain cost for the material used to make the template, the template can be reused, and the template can be numbered and classified and used on the tarpaulin of other models of vehicles.

Fig. 3 PVC Soft Glass Glue Board
Fig. 4 Tarpaulin Deformation Camouflage Template

2 Digital camouflage pattern spraying method
2.1 Digital camouflage spot coating procedure
(1) First, according to the specific shape of the equipment and the requirements of GJB 7929-2012, draw a batch of digital camouflage spot template drawings and number them (see Figure 5), choose 2 A thickness of PC endurance board with a thickness of mm was carved with a batch of templates [see Fig. 6 (a), (b)]. In addition, the middle part of the template was cut and left for use [see Fig. 6 (c)].

Camouflage Template Drawing
Camouflage Template

(2) According to the working environment of the equipment, according to the requirements of GJB 7929-2012, use the existing camouflage spot template to design the camouflage construction drawing of the equipment (see Figure 7), determine the color of the camouflage spots, and the area percentage and distribution of each colored spot. Happening.

Digital Camouflage Painting

(3) Apply camouflage coating on the product, first apply the protective color, and then the builder uses the pen and ruler to locate the car body according to the construction drawing, draw a reference line, and indicate the color separation here You need the template number and color (see Figure 8), and use this method to locate the template of the entire vehicle.

 Fig. 8 Distribution of the Vehicle Body's Reference Lines

(4) Position the corresponding template [as shown in Figure 6 (a), Figure 6 (b)] to the corresponding position of the car body according to the baseline. One worker presses the template and the other sprays it. In order to prevent the paint from splashing onto the adjacent patches of different colors, the effect of this method after spraying is shown in Figure 9.

Fig. 9 Effect of Template Spray Painting

(5) For some special-shaped surface templates that are difficult to cover, use the corresponding template middle part [see Figure 6 (c)] to draw digital camouflage spots at the corresponding positions with color separation bands (see Figure 10), and then use half Transparent paper or newspaper isolates unpainted areas (see Figure 11). The effect of this method after spraying is shown in Figure 12.

Fig. 10 Camouflage Spots Outlined with Color Distinguishing Ribbons
Fig. 12 Effect of Spray Painting

2.2 Composition of
camouflage paint for protective colors and camouflage spots The raw materials of camouflage paint are composed of base material, pigment and auxiliary materials.
Binder: Commonly used are butyl rubber, neoprene, butyl rubber, polyisobutylene, polyvinyl chloride, polyurethane, etc.
Pigments: ferromagnetic materials composed of metal oxides such as MgO, FeO, Fe2O3, ZnO, conductive materials such as smoke black, graphite, carbon black, scaly aluminum powder, hair, animal hair, ceramics, etc. It is composed of camouflage paint The core part.
Auxiliary materials: The use of auxiliary materials is to improve and improve the physical and mechanical properties, construction properties, and surface conditions of the coating.

2.3 Performance requirements of
camouflage paint Camouflage paint should have good camouflage performance and protection. Camouflage performance usually refers to spectral reflectance and gloss. Anti-visible, near-infrared solvent-based camouflage paint is composed of natural and synthetic resins, special pigments, plasticizers, etc. It should meet the following requirements:
(1) It has reconnaissance capability against visible light and near-infrared (working band 380 ~ 1 100nm).
(2) The color and appearance quality of the coating film shall conform to the standard samples provided by the military.
(3) viscosity (coated 4 cups) 80 ~ 150 s.
(4) Fineness ≤50 nm.
(5) Solid content ≥30%.
(6) Drying time: quick-drying: surface drying <10 min, hard-drying <120 min; slow-drying: surface dry <2 h, hard-drying <24 h.
(7) Flexibility ≤3 mm.
(8) Impact resistance ≥50 kg · cm.
(9) Adhesion ≤ 2 grade.
(10) Gloss: 20% to 40%.
(11) Resistant to 3% salt water immersion for 24 hours, the coating film does not foam, wrinkle, and does not change color.
(12) Resistance to 75 # aviation gasoline soaked at room temperature for 2 hours, the coating film does not foam, wrinkle, and does not fall off.
(13) The color fastness of the coating film to 200 h should be ≥ 5 grade.
(14) The mold resistance of the coating film for 7 days should be ≤ 2 grade.
(15) The salt spray resistance of coating film for 7 days shall be ≤ 2 grade.
(16) Moisture and heat resistance of coating film 7 d should be ≤ 2 grade.

2.4 Spraying process details
(1) Manual rust removal: The residual rust on the surface of the entire vehicle is cleaned by manual grinding.
(2) Grinding feather edges: Use a sander and 120 # sandpaper to grind feather edges.
(3) Dedusting: Use air compressor to blow away the dust on the corners, convexities and depressions of the entire vehicle, and the floating dust on the surface of the vehicle.
(4) Cleaning and degreasing: Clean the degreasing with a non-woven cloth moistened with 120 # gasoline.
(5) Protection before painting: All non-painting parts on the finished car are coated with oil-in-paper to prevent pollution by paint mist.
(6) Spot atomic ash: Spot the atomic ash where there are serious defects in the coating. After drying, polish and flatten, and blow the surface of the workpiece with compressed air.
(7) Spray protection color: Use spray gun to spray the surface of the finished car with acrylic-polyurethane magnetic paint by air spraying. The distance between the spray gun and the workpiece (300 ~ 500 mm) and the running speed (300 ~ 500 mm / s). The principle of painting: Spray evenly from top to bottom, from inside and outside. Construction viscosity: 20 ~ 26s, construction relative humidity ≤85%, construction temperature: room temperature.
(8) Spray camouflage spots: According to the designed equipment camouflage construction drawings, spray camouflage spots from light to deep.
(9) Inspection.

2.5 Precautions for digital camouflage spraying
(1) Special pencils should be used for camouflage spots to avoid scratches and corrosion on the paint surface.
(2) The number and color of the spot template should be marked in time when positioning to avoid confusion.
(3) Pay attention to the selection of the template material. The material should not be too thick, otherwise the transition between the spot and the entire paint surface is clear, and you will feel obvious steps when you touch it with the hand. In addition, the material should be soft and moderate, and too hard to be comfortable. Soft is easy to deform and cannot be reused.
(4) When implementing digital camouflage spraying, first spray the background color, and then spray the camouflage spots one by one from light to deep. When spraying a spot of one color, pay attention to isolating the parts that do not need to be sprayed. The border between the two colors should be prevented from mixing.
(5) When spraying spots, adjust the amount of paint from the spray gun to the minimum. First outline the spots, and then spray the entire spot. After each digital spot is sprayed, spray a certain amount on the spot and its surroundings as soon as possible. Thinner to eliminate strip marks and uneven wet and dry phenomena during spraying, make the paint surface more flat, uniform and delicate, and then spray the remaining spots until the vehicle is complete.

3 Conclusion
After the production and construction in accordance with the above methods, the spray effect of the car body and camouflage camouflage has been significantly improved. In addition, the technical level of construction personnel spraying car body and tarpaulin camouflage spots has also been significantly improved, ensuring that the camouflage camouflage spraying of products is carried out smoothly.

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