German EB company is a famous foundry enterprise in the foundry industry. It is a family factory with a history of 80 years. It is known as the most advanced technology, the lowest cost and the best quality in the world. EB produced 293000 tons of cylinder blocks in 2007, with an output value of 330 million euros, 1380 employees and 150 long-term temporary workers, with an annual per capita production of 192 tons of cylinder blocks. The company’s products are mainly four cylinder blocks, with an internal waste rate of about 3% and an external waste rate of less than 1%. The company improves the engine block blank for world high and middle-end automobile companies such as Mercedes Benz, BMW, Ford and Volkswagen. Its product quality is stable for a long time and has high brand value. The castings produced by the company basically have no casting defects such as porosity, sand inclusion, sand hole and sand sticking.
Sandbox size 1300 × nine hundred × 300/300mm，1180 × seven hundred and seventy × 300/300mm。 One molding line produces four different cylinder castings at the same time. Two sand systems: back sand system and surface sand system; Four 100 ton sand silos and one 100 ton standby sand silo.
The back sand system adopts 4 sets of sand mills with a capacity of 3 tons, with automatic weighing function, quantitative water and clay, intermittent mixed grinding, grinding 3 tons, taking 90 seconds; Process: used sand – magnetic separation – Screening – cooling – sand grinding – sent to the molding workshop. Different from that in China, EB’s cylinder block sand mold surface adopts one layer of sand, and the surface sand system adopts two 1-ton sand mills. The surface sand comes from the fine sand screened from the old sand and the new surface sand purchased separately. The surface sand is mixed and rolled only once for 4 minutes.
Sand temperature control, old sand temperature 30 ℃ – 35 ℃; During sand grinding, the molding sand temperature is 30 ℃ – 35 ℃, and the qualified molding sand temperature for molding is 25 ℃. Through bottom blowing and top spray boiling to reduce the sand temperature, the sand temperature control of EB plant is easier.
The cylinder block of dafalong King factory in Japan adopts ace static pressure molding line produced by Xindong company in Japan, and the size of sand box is 920 × seven hundred × 275/275mm。 The hardness of the sand mold is uniform, and no waste mold can be seen. The hardness at the center of the sand mold is 97, and the hardness at the edge of the sand mold is more than 90. The hardness standard is a hardness standard used in Japan. The effective bentonite content in the molding sand of the plant is 8.5-10%, and the total mud content is about 10-12%; Japan’s Xiaoshan factory has 5 cast iron molding lines, of which the latest cylinder block production line is the ace molding line produced by Japan’s Xindong company. The temperature of molding sand mixed from the sand mixer for molding is generally 20 ℃, and the maximum temperature in summer is 30 ℃. The temperature of used sand before entering the sand mixer is 40-45 ℃, and the moisture is 1.5-2%. The effective bentonite content of molding sand is 8.5-9%, the total mud content is 10.5-11%, and the moisture content of molding sand is 3.0-3.3%.
Xindong FengChuan production Institute puts forward a new theory for the quality control of molding sand, emphasizing that the newly added clay does not play any role before the first burning loss, and what really plays a role in the casting is a material called Colitics covered on the sand surface after burning loss; In the process of premixing, the newly added clay is always free outside the Colitics, and the water is also free outside the Colitics; Storing in the sand bin for 1.5-2.0 hours can play the role of water penetrating into the Colitics, but the new clay still does not really contact with the sand and play a role. As shown in the figure.