Titanium alloy pump body investment casting

Titanium alloy pump body investment casting

Titanium and titanium alloy investment casting parameters

Due to the poor casting performance of titanium, the cast channel setting of the titanium investment mold is particularly important. If the cast channel is vertically cast according to the method of casting cobalt-chromium alloy and stainless steel, incomplete casting will often occur. The surface treatment of titanium castings is very important. Due to the special physical properties of titanium, such as titanium's small thermal conductivity, surface hardness, low elastic modulus, high viscosity, low electrical conductivity, easy oxidation, etc., these are very important for the surface treatment of titanium. This brings great difficulty. Conventional surface treatment methods are difficult to achieve the desired effect, and special processing methods and operating methods must be used. The cast channel for titanium investment mold has the following requirements:

The diameter of the cast channel should be thick (not less than 4mm) and short to ensure that a sufficient amount of titanium liquid is injected into the casting cavity through the shortest way; the connection between the cast channel and the investment mold should be appropriately thickened; the number of cast channels should be 3~ 4 pieces; can be inserted parallelly or sideways; avoid forming right angles. 2. Effect of casting mold temperature on surface properties of titanium castings. The contamination of the titanium liquid by the investment material is not only related to the vacuum degree of the casting chamber and the composition of the investment material, but also related to the temperature of the casting mold. When the casting mold temperature is high, the titanium liquid easily reacts with the investment. Elements such as Zr, Al, and Si can easily diffuse into the titanium matrix and become interstitial elements, forming a thicker hardened layer, thereby reducing the tensile strength and yield of the casting. Strength increases, ductility decreases, and brittleness increases. Among them, the increase in oxygen content has the most obvious change in the mechanical properties of castings. The hardened layer also becomes thinner when the mold temperature is low. However, low mold temperature will affect the casting flow rate, so the mold temperature must be appropriately selected, and sometimes the mold temperature must be determined according to different purposes.

Titanium pump body casting process

In China, due to the limited melting capacity of the vacuum solidifying furnace, knot casting has brought difficulties. In order to save liquid metal titanium, the top injection process is adopted.

① Model process design: The casting mold is machined graphite type and consists of 12 pieces. The casting structure design is relatively reasonable and achieves the expected goals.

②Pouring and melting process: Although the casting mold has been vacuum degassed, due to the large size of the casting mold and core, gas will still be released after pouring. If the gas cannot be discharged from the mold cavity in time, pore defects will occur in the casting. . In order to solve this problem.

③ Liquid flow dividing ribs are designed in the volute of the pump body to balance the radial force, which is especially necessary for large flow and high lift pumps. However, due to its existence, the design and manufacture of the knot core brings great difficulties. In order to prevent breakage during future degassing and pouring processes, reinforcement measures should be taken.

The post-surface treatment of the titanium pump body is not only to obtain a smooth surface, reduce the accumulation and adhesion of food and plaque, maintain the patient's normal oral microecological balance, but also increase the aesthetics of the denture; more importantly, Through these surface treatment and modification processes, the surface properties and adaptability of titanium castings are improved, and the wear resistance, corrosion resistance, stress fatigue resistance and other physical and chemical properties of dentures are improved.