Speaking of V method vacuum molding line modeling, is a physical modeling process. It means that no binder, water and other additives are added to the molding sand, thus reducing the workload of sand treatment and greatly reducing the amount of molding and casting sand removal. The reuse rate of old sand can reach 95%.

This casting process is a physical molding method that USES plastic film to seal the sand box and relies on the vacuum pump to extract the inner air of the mold, resulting in pressure difference between the inside and outside of the mold and compacting the dry sand to form the required cavity. Therefore, the vacuum sealing molding is also known as "negative pressure molding method", or vacuum sealing molding, which is collectively referred to as "V method molding casting process". Compared with the traditional sand mold casting process, the equipment investment can be reduced by about 30% by adopting the v-method molding. The molding USES wood as the template and welded steel plate to make the sand box. Therefore, the service life of the model and the sand box is long, the production cycle is short, the material utilization rate is high, the casting rejection rate is reduced, and the internal and external quality is improved, thus the casting cost is reduced. Vacuum V molding can be used to produce castings, steel castings and non-ferrous alloy castings, and even large thin-walled castings, depending on the shape of the castings.

V method vacuum molding line process are what

(1) models and templates: models and reception-plates with air extraction Chambers and air holes are manufactured. The model is fixed on the receptacle plate, and the edge and key parts of the model are provided with air holes, which are directly connected with the template cavity. When the cavity is under negative pressure, air is pumped through the air vent.

(2) laminating heating: a piece of plastic film about the size of the receiving plate is heated to the softening state, the film thickness is generally 0.08mm~0.2mm, and has good scalability and high plastic deformation rate.

(3) : vacuum membrane softening, immediately began to work, make a vacuum device to soften the membrane is sucked on the model, by vacuum suction air holes on the film, the film and the model of close together, with vacuum system after extraction effect of receiving plate and the model of the air, make the film clingy on receiving plate and the model, the formation of sand filling with receiving plate (called coated molding), to spray on quick drying coating on the model.

(4) placing the sand box: the vacuum suction continues to act on the model bearing plate, and the sand box with the filtration and extraction system is placed around the model and above the film. The sand box is a double-layer box wall structure, and a vacuum chamber is formed between the two layers of the box walls. Air holes are drilled on the inner wall of the sand box, and a metal screen is set between the two layers to prevent fine sand and dust from entering the vacuum chamber. The larger sand box can be equipped with a vacuum hose inside, and the hose is connected to the vacuum tank and connected to the vacuum pump.

(5) add sand to the sand box: fill dry quartz sand without binder or additives into the sand box, start the shaking table, vibrate the sand in the sand box and scrape the sand surface, place the shape of pouring riser, lay plastic film seal on the sand surface, open the suction valve, and extract the air from the sand, so that the pressure difference between the inside and outside of the mold is formed. Due to the effect of the pressure difference, the cast mold has a high hardness after molding, the hardness meter reading reaches 80~90, and the highest can reach 90~95.

(6) top surface of sand mold coated with film: the top of the sand mold is covered with a layer of plastic film, the film does not need to be heated and softened, only plays a sealing role, the same role as the lost foam casting used for sealing plastic film. Figure 6 shows that the upper mold is connected to the sprue runner by hand, and the lower mold only needs to scrape the sand flat before laminating.

(7) sand box vacuum pumping: vacuum the sand box, and the vacuum degree of the model bearing plate is released. Under the action of atmospheric pressure, the sand in the sand mold is compacted and maintains its original shape, and then the sand mold is separated from the model, that is, the mold is removed.

(8) closing casting: the upper and lower moulds are produced in the same way, and the upper moulds are placed on the top of the lower moulds, forming a whole cavity lined with plastic film, as shown in FIG. 8. Remove the vacuum in the mold plate, inject positive pressure into the mold plate, and then carry out the mold lifting. After that, the mold shall continue to be vacuumed, and then the core, box closing and casting shall be carried out.

(9) sand falling: after casting, after the metal liquid is gradually cooled and solidified, the negative pressure degree is gradually reduced. When the pressure inside the mold is close to or equal to atmospheric pressure, the pressure difference within the mold disappears and the sand mold breaks down on its own, as shown in FIG. 9. (note: the holding time shall be determined according to the thickness and size of the casting.) After cooling, remove the vacuum tube and drop the sand directly with the casting without vibration. After sand cooling, return to the system for recycling, and remove the casting into the cleaning department.