Thermal plastic spraying forming method of cast composite coating

Abstract

The invention discloses a thermal plastic spraying forming method of a cast composite coating, which comprises the following steps: uniformly mixing a high polymer material and aggregate to obtain a premix; adding the mixture into a material making machine for material making to obtain prefabricated granules; and the prefabricated granules are added into an injection heating device and heated to the melting temperature for plasticizing treatment, and the granules subjected to plasticizing treatment are sprayed to the surface of a casting mold under the pressurization condition. According to the method for directly spraying the coating on the surface of the casting mold in the injection molding spraying process, molten metal casting forming can be conducted without curing treatment after the inner surface of the casting mold is sprayed, the coating can be sprayed to the surface of the casting mold at a time, and the casting mold composite coating in casting can be prepared without cooperation of multiple additional working procedures; the method has the advantages of high efficiency, environmental protection, low carbon and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of material processing, and particularly relates to a hot spraying and plastic forming method for a casting composite coating. Background Art

[0002] In the casting industry, the surface of the casting mold plays roles such as high-temperature resistance, anti-permeation, anti-impact, and reduction of sand sticking through the coating. The traditional method is to mix high-temperature-resistant aggregates with various solvents and binders and manually apply them on the surface of the casting mold, and then use methods such as high temperature and combustion to remove the moisture in the coating. However, the disadvantages of this traditional process are that the coating needs to add some chemically reagents or ethanol with certain pollution, and the manual operation efficiency is low. Therefore, it is necessary to develop a new high-efficiency, environmentally friendly and green casting mold coating process method.

[0003] The casting mold coating requires sticking high-temperature-resistant aggregates on the surface of the casting mold. If the binder can be pre-plasticized and evenly mixed with the aggregates in advance, these coatings can be sprayed on the surface of the casting mold. Generally speaking, the plasticization temperature range of the high-temperature-resistant thermoplastic binder is relatively narrow, only about 60 °C. When the temperature is too high, the binder will crack, and when the temperature is too low, the fluidity of the binder will disappear. This characteristic also enables the heated thermoplastic to quickly solidify after spraying. Compared with the manual brushing and electrostatic cold spraying and plasticizing technology, the hot spraying and plasticizing method can achieve one-time forming of the casting mold coating without reheating after spraying. Summary of the Invention

[0004] The main purpose of the present invention is to provide a hot spraying and plastic forming method for a casting composite coating, which wraps high-temperature-resistant aggregates in a polymer binder and sprays them on the surface of the casting mold in an injection spraying manner to achieve one-time forming of the casting mold coating.

[0005] The above object of the present invention can be achieved by the following technical solutions:

[0006] The present invention provides a hot spraying and plastic forming method for a casting composite coating, including the following steps:

[0007] Step 1: Uniformly mix the polymer material and the aggregates to obtain a premix; then add it to a material making machine for material making to obtain prefabricated pellets;

[0008] Step 2: Add the prefabricated pellets to an injection heating device;

[0009] Step 3: Heat the prefabricated pellets to the melting temperature for plasticization treatment;

[0010] Step 4: Under the condition of pressure, spray the plasticized pellets onto the surface of the casting mold.

[0011] Preferably, in Step 1, the casting composite coating is a casting polypropylene and chromium iron powder composite coating.

[0012] Preferably, the polymer material is polypropylene pellets, and the aggregate is 320-mesh chromium iron powder, with a mass ratio of 1:8-12.

[0013] More preferably, the polymer material is polypropylene pellets, and the aggregate is 320-mesh chromium iron powder, with a mass ratio of 1:10.

[0014] Preferably, in step 3, the melting temperature is 220-280 °C, preferably 250 °C.

[0015] More preferably, in step 3, the melting temperature is 250 °C.

[0016] Preferably, in step 4, the pressurization condition is pneumatic atomization.

[0017] Compared with the prior art, the present invention proposes a method for directly spraying a coating on the surface of a mold during the injection molding process. After the inner surface of the mold is sprayed, no further curing treatment is required, and the mold coating can be formed in one step, and then the molten metal can be cast. The beneficial effects are as follows: By adopting the heating method of the injection mechanism, while the screw is stirring, the screw rotates to push the pellets into the heating area, and the material temperature is relatively uniform. Considering that the viscosity of the polymer binder is relatively large, the liquid-solid aggregate is sprayed out by a large pressure method, and the coating can be sprayed onto the mold surface at one time, and the preparation of the mold coating in casting can be realized without the cooperation of multiple additional processes, which has the advantages of high efficiency, environmental protection and low carbon. Specific Embodiments

[0018] The present invention will be further described below in conjunction with embodiments.

[0019] The present invention realizes the formation of a composite mold coating by injecting and heating and spraying a composite coating onto the surface of the mold.

[0020] Example 1

[0021] This example prepares a polypropylene and chromium iron powder composite mold coating, and the steps are as follows:

[0022] Step 1: Prepare polypropylene pellets and 320-mesh chromium iron powder, with a mass ratio of 1:10.

[0023] Step 2: Add the powder and pellet materials prepared in Step 1 to a material preparation machine for material preparation.

[0024] Step 3: Add the prepared composite pellets to an injection device and heat to 250 °C for plasticization treatment.

[0025] Step 4: The plasticized pellets are sprayed onto the surface of the mold by pneumatic atomization.

[0026] After the inner surface of the mold is sprayed, there is no need for further curing treatment, and the molten metal can be cast immediately, with high efficiency.

[0027] Comparative Example 1

[0028] Using the commonly used manual brushing at home and abroad, the coating contains a variety of chemical reagents, which pollute the environment to a certain extent and increase carbon. After coating, it needs to be heated and cured or dried for a long time.

[0029] In summary, the mold coating is required to be heat-resistant and not pollute the casting. The main component of the coating is heat-resistant aggregate, and the polymer binder is an auxiliary component. The polymer material as the binder and the heat-resistant aggregate are mixed to make a material, and then heated in an injection device. The binder is completely plasticized into a liquid phase, and then sprayed onto the mold under high pressure. Since the liquid phase temperature range of this type of binder is narrow, it is immediately cured into a coating on the mold, which is environmentally friendly and efficient.

[0030] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the present invention is not limited to the above embodiments, and all improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A method for thermal spraying a casting composite coating, characterized in that: The following steps are involved: Step 1, uniformly mix the polymer material and the aggregate to obtain a premix; then add the premix to a material making machine for making the material to obtain prefabricated pellets; Step 2, adding the prefabricated pellets into an injection heating device; Step 3, heating the prefabricated pellets to a melting temperature for plasticization; Step 4: spray the plasticized pellets onto the surface of the mold under pressure.