Current status and development direction of engineering machinery painting technology in China

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The coating of engineering machinery products is the first step in the competition of products. Everyone attaches great importance to it; in order to adapt to the city, it can adopt the baking process.

(3) Adhesion. Coating adhesion is an important indicator of mechanical strength. The key to good adhesion is pretreatment, and the most reliable pretreatment process is shot blasting. Therefore, structural parts of construction machinery products generally adopt shot blasting methods.

(4) Weather resistance. Construction machinery generally works in an outdoor environment and requires a weather-resistant coating material.

(5) Gloss. The gloss of the coating film depends on the fineness of the atomization of the spraying equipment. The finer the atomization, the better the gloss. The airless spraying with better atomization should be used as much as possible.

2. Painting process

The characteristics of engineering machinery products are variety, specifications, volume, weight, different production characteristics and different use environments, different production programs, and various coating processes. Since the production machinery of the construction machinery was small before the 1990s; the typical process flow is:

Structural parts: shot blasting (or shot peening) → cleaning → spray primer → drying → scraping putty → drying → assembly.

Machine: cleaning → water drying → scraping putty → drying → polishing and cleaning → surface coating 1 → drying → top coating 2 → drying → finished product. (Water drying and putty drying are mostly done in a dry manner.)

The development of engineering machinery has evolved to the present, and its typical process flow has undergone major changes. The typical process flow is:

Structure:

(1) Commonly used processes: shot blasting → cleaning → spray primer → drying → scraping putty → sanding and polishing → medium coating → drying → top coating → drying → assembly.

(2) The latest technology: shot blasting → cleaning → (degreasing, phosphating, pure water washing and spraying) → moisture drying → primer coating → volatile leveling → surface coating → leveling → drying → assembly.

Machine: cleaning → water drying → repair putty finishing and bottom spraying → drying → finished product

3. Painting materials

The surface paint for construction machinery generally adopts self-drying paint which can be dried at low temperature. The varieties mainly include modified alkyd enamel, acrylic engineering mechanical enamel, polyurethane enamel, etc., which meet the requirements of different customers.

The coating uses a low-temperature drying process to improve its adhesion and hardness. Topcoats must be matched with primers, putties and intermediate coating systems. Topcoat materials are the main factors for the difference in the quality of coatings at home and abroad. It is waiting for domestic coatings manufacturers to develop high quality and low price products to meet the needs of the domestic market.

4. Process layout

The construction machinery structural parts and the whole machine coating production line are mainly composed of structural parts shot blasting room, machine cleaning room, moisture drying room, grinding room, painting room, paint film drying room, finishing room and conveying equipment.

The layout of the process equipment is closely related to the product characteristics and the coating process used. Whether the product is wheeled or crawler type, which kind of putty is scraped, whether the middle coating process or the like affects the whole process layout.

The layout of the process is closely related to the conveying mode of the production line. At present, the domestic structural parts are generally coated with self-hoisting with the function of accumulation; there are three main ways of coating production lines: double-plate chain transportation, transfer vehicle transportation and self-propelled mode. The two methods are arranged in a pipeline, and each process is completed in a separate chamber.

5. Painting equipment

5.1 structural parts shot blasting room

The surface of the structural parts is treated by automatic shot blasting. The shot blasting process is to shoot the abrasive at a certain speed on the surface of the steel to be treated. The impact and grinding effect of the abrasive on the surface of the steel will cause the scale and corrosion of the surface of the steel. A highly efficient surface treatment for the removal of products and other contaminants. The through-polishing (spraying) pill cleaning chamber is composed of a cleaning chamber body, a blasting machine, a shot blasting cylinder, a spray gun, a projectile circulation system, a ventilation dust removal system, a bottom structure, an electrical control system and the like.

(1) Clean the room body in the best position to install the blasting machine (the quantity is determined according to the shot blasting amount), and the blasting machine is arranged obliquely to ensure that every part of the workpiece can be cleaned up, that is, the longest piece is considered, and at the same time Take care of the widest and highest pieces. When the workpiece is thrown in the shot blasting area, it must have a uniform speed movement. At the same time, the chamber door must be closed to ensure that the pellet does not fly out of the room. The lining guard in the shot blasting chamber is made of high manganese cast steel guard plate, which is versatile and mutual. Good changeability and long wear life.

(2) A shot blasting tank is provided at the outlet end of the shot blasting chamber, equipped with two spray guns, and the inner wall is protected by wear-resistant rubber sheets, which not only ensures the reliability of the equipment, but also reduces the cost of the equipment. There are electric gates in the inlet and outlet of the chamber, which can be controlled automatically or manually.

5.2 water spin spray booth

The spray booth consists of a chamber body, a delivery and exhaust system, a lighting system, a paint mist treatment system, a control system, and a flammable gas concentration alarm device.

(1) A static pressure chamber is arranged on the upper part of the chamber body, and is designed integrally with the spray booth skeleton. The high-pressure filtering non-woven fabric is arranged in the static pressure chamber, so that the clean air sent into the chamber body is pressed down along the top of the chamber body in a laminar flow state, thereby effectively controlling the diffusion of the paint mist.

(2) The air supply system needs to set the initial and intermediate effect filter section and the heating section (the heat source is steam, and the indoor indoor hot air is ≥15 °C). The air supply requires uniform wind speed at each section to avoid paint mist.

(3) The paint mist purification efficiency requirement is above 99%; the air exhaust system is provided with a gas-water separation device, which is discharged into the atmosphere after being treated.

(4) Organic waste gas treatment meets the national comprehensive emission standards for air pollution. The exhaust gas monitoring and alarming device monitors the concentration of indoor combustible gas at any time. When the solvent concentration reaches 25% of the lower explosion limit, it will immediately alarm.

5.3 bottom (face) paint drying room

The drying chamber adopts a forced hot air convection circulation mode. The energy of the drying room mainly includes steam, electricity, liquefied gas, light diesel oil, etc. The equipment is mainly composed of a chamber body, a hot air circulation system and an exhaust gas purification device. The hot air circulation system now uses a quaternary heating furnace (inserted fan, fuel heating system, high temperature filter, exhaust gas treatment integrated structure). The heating rate is fast, the indoor temperature is uniform, and the temperature difference is <+5O °C.

Product name         Aluminium tripolyphosphate/Aluminum Tripolyphosphate Hydrate

CAS No              13939-25-8

EC No                237-714-9

Chemical formula      Al5.(P3O10)3

Appearance           White Powder

Storage               Keep the product in a tightly closed container ,Isolate form any source of heat or ignition and moisture

Packing unit          25kg Poly Propylene bag & 500kg Poly Propylene bag,

Any size customers want.

Application           Material for anti-corrosion paint used in container,

Ship and steel structures .Electronic materials

Goods characteristics   White Powder.

Soluble in acid or alkali solution ,insoluble in water or alcohol.

 

CHEMICAL ANALYSIS

 

TEST ITEM

UNIT

REQUIREMENT

Whiteness

%

80-90

Al2O3

wt.%

20±5

P2O5

wt.%

35-40

SiO2   %

 

wt.%

8-12

Moisture

wt.%

Max1.0

Oil absorption

ml/100g

25-35

The PH Value

-

5.5-7.0

Residue on sieve (325mesh)

wt.%

Max0.5

Mean Particle Size

μm

44

Aluminum tripolyphosphate

Aluminum Tripolyphosphate Powder,Aluminum Tripolyphosphate,Aluminum Tripolyphosphate Pigment,Anti-Corrosive Aluminum Tripolyphosphate,Aluminum Tripolyphosphate Hydrate

shijiazhuang city xinsheng chemical co.,ltd , http://www.xsphos.com