阅读说明：本技术 镍磷合金铸件低压铸造工艺 (Low-pressure casting process of nickel-phosphorus alloy casting ) 是由 邹彩花 于 2019-11-14 设计创作，主要内容包括：本发明公开一种镍磷合金铸件低压铸造工艺,先将有色金属在一定的温度下浇注成金属液,待金属液凝固冷却后,形成型板,将烘烤呈塑性状态的塑料薄膜覆盖在型板上加热,控制温度,同时真空泵抽气使薄膜密贴在型板上成型；将带有过滤抽气管的砂箱放在已覆好塑料薄膜的型板上；向砂箱内充填干石英砂,借微震使砂紧实,刮平,放上密封薄膜、通过过滤抽气管抽去箱内空气,达到一定压力后,解除箱内的真空,制成成品,本发明提供一种镍磷合金铸件低压铸造工艺,具有提高了铸件精度,减少了机械加工工作,降低了成本,节省能耗,延长了使用寿命,方便使用优点。(The invention discloses a low-pressure casting process of a nickel-phosphorus alloy casting, which comprises the steps of firstly, pouring nonferrous metal into molten metal at a certain temperature, forming a template after the molten metal is solidified and cooled, covering a plastic film which is baked in a plastic state on the template for heating, controlling the temperature, and simultaneously, exhausting air by a vacuum pump to enable the film to be tightly attached to the template for molding; placing a sand box with a filtering and air extracting pipe on a template coated with a plastic film; the invention provides a low-pressure casting process for a nickel-phosphorus alloy casting, which has the advantages of improving the casting precision, reducing machining work, reducing cost, saving energy consumption, prolonging service life and being convenient to use.)

1. A low-pressure casting process of a nickel-phosphorus alloy casting is characterized by comprising the following steps: the low-pressure casting process of the nickel-phosphorus alloy casting comprises the steps of preheating a blank to form molten metal, filling the molten metal into a sealed container with a casting cavity, introducing dry compressed air to act on the molten metal level which keeps a certain casting temperature, forming a certain pressure, crystallizing and solidifying the molten metal in the casting cavity under the action of higher pressure, and then removing the pressure in the sealed container to obtain the casting.

2. A low-pressure casting process for nickel phosphorous alloy castings according to claim 1, characterized in that: the certain pressure is 0.01-0.05 MPa.

3. A low-pressure casting process for nickel phosphorous alloy castings according to claim 1, characterized in that: the preheating temperature is 100-150 ℃.

4. A low-pressure casting process for nickel phosphorous alloy castings according to claim 1, characterized in that: and keeping a certain pouring temperature at 80-120 ℃.

5. A low-pressure casting process for nickel phosphorous alloy castings according to claim 1, characterized in that: the blank is nickel-phosphorus alloy or aluminum alloy or steel alloy.

6. A low-pressure casting process for nickel phosphorous alloy castings according to claim 1, characterized in that: the higher pressure is 0.5-1 MPa.

Technical Field

The invention relates to a low-pressure casting process of a nickel-phosphorus alloy casting.

Background

The cast nickel-phosphorus alloy is obtained by filling molten metal into a casting mold to obtain aluminum alloys of parts blanks in various shapes. The high-strength high-corrosion-resistance high-strength. The method is also used for manufacturing parts such as a cylinder cover, a gearbox and a piston of an automobile, a shell of an instrument, a booster pump body and the like. The cast nickel-phosphorus alloy has good casting performance and can be made into parts with complex shapes; no bulky additional equipment is required; the casting process has the advantages of saving metal, reducing cost, reducing working hours and the like, but when the traditional nickel-phosphorus alloy casting is cast, the problems of air hole bubbles, shrinkage porosity, cracks and the like can be generated, so that the surface is not smooth, the casting structure is loose and the like, and the performance and the service life of the casting are influenced.

Disclosure of Invention

The invention aims to provide a low-pressure casting process for a nickel-phosphorus alloy casting, which has the advantages of improving the casting precision, reducing machining work, reducing cost, saving energy consumption, prolonging service life and being convenient to use.

The technical scheme of the invention is as follows: a low-pressure casting process for the Ni-P alloy cast includes such steps as preheating the raw material to form molten metal, loading it in a sealed container with mould cavity, introducing dry compressed air, acting on the molten metal at a certain temp, generating a certain pressure, crystallizing and solidifying the molten metal in the mould cavity under higher pressure, and removing the pressure in the sealed container.

In a preferred embodiment of the invention, said certain pressure is between 0.01 and 0.05 MPa.

In a preferred embodiment of the present invention, the temperature of the preheating is 100-150 ℃.

In a preferred embodiment of the invention, the certain casting temperature is maintained at 80-120 ℃.

In a preferred embodiment of the invention, the blank is a nickel-phosphorus alloy or an aluminum alloy or a steel alloy.

In a preferred embodiment of the invention, the higher pressure is between 0.5 and 1 MPa.

The low-pressure casting process of the nickel-phosphorus alloy casting has the advantages of improving the casting precision, reducing machining work, reducing cost, saving energy consumption, prolonging service life and being convenient to use.

Detailed Description

The following detailed description of the preferred embodiments of the present invention is provided to enable those skilled in the art to more readily understand the advantages and features of the present invention, and to clearly and unequivocally define the scope of the present invention.

The invention relates to a low-pressure casting process of a nickel-phosphorus alloy casting, which comprises the steps of preheating a blank to form molten metal, filling the molten metal into a sealed container with a casting cavity, introducing dry compressed air to act on the molten metal surface which keeps a certain pouring temperature, forming a certain pressure, crystallizing and solidifying the molten metal in the casting cavity under the action of higher pressure, and then removing the pressure in the sealed container to obtain the casting.

Further, the certain pressure is 0.01-0.05MPa, the preheating temperature is 100-150 ℃, the certain pouring temperature is 80-120 ℃, the blank is nickel-phosphorus alloy or aluminum alloy or steel alloy, and the higher pressure is 0.5-1 MPa.

Further, the pouring temperature is too high, the shrinkage is large, so that the casting is easy to crack, the grain size is large, and the sticking can be caused; the casting temperature is too low, and the defects of cold shut, surface patterns, insufficient casting and the like are easy to generate. The casting temperature should therefore be taken into consideration simultaneously with the pressure, the die casting temperature and the filling rate. The temperature of the die casting mold is preheated to a certain temperature before use, and generally, gas, a blast lamp, an electric appliance or induction heating is used for multiple purposes. In continuous production, die casting temperature tends to rise, particularly rapidly for die casting high melting point alloys. When the temperature is too high, the liquid metal is sticky, and the casting is slowly cooled, so that the crystal grains are coarse. Therefore, when the die casting temperature is too high, cooling measures should be taken. Cooling is usually performed with compressed air, water or a chemical medium. Filling, pressure maintaining and opening time 1) the filling time is from the beginning of the liquid metal entering the cavity to the end of the filling of the cavity, and the required time is called the filling time. The length of the filling time depends on the size and complexity of the volume of the casting. For large and simple castings, the filling time is relatively long, and for complex and thin-walled castings, the filling time is short. The filling time is closely related to the sectional area of the ingate or the width and thickness of the ingate, and must be determined correctly. 2) The duration of the hold pressure and open time from the time the liquid metal fills the cavity until the gate is fully solidified, and continuing under the action of the injection punch, is referred to as the hold pressure time. The length of the holding pressure time depends on the material and the wall thickness of the casting. And opening the mold after holding and pressing to take out the casting. The time from the end of injection to the opening of die casting is called opening time, and the opening time is controlled accurately. The opening time is too short, and the alloy strength is still low, so that deformation can be caused when a casting is ejected out and a self-pressing casting mold falls; however, if the mold opening time is too long, the temperature of the casting is too low, the shrinkage is large, and the resistance to core pulling and casting ejection is also large. The open time is generally calculated according to the requirement of 3 seconds for the wall thickness of the casting to be 1 mm, and then the open time is adjusted by trial and error. In the die-casting process of the die-casting coating, in order to avoid welding of the casting and the die-casting mold, the friction resistance of the ejection of the casting is reduced, and the die-casting mold is prevented from being excessively heated and is coated. The requirements for the coating are as follows: 1) at high temperature, the lubricating agent has good lubricity; 2) the volatilization point is low, and the diluent can be volatilized quickly at 100-150 ℃; 3) no corrosion to die casting and die casting; 4) the performance is stable, and the thinner in the air can not be thickened due to excessive volatilization; 5) no harmful gas is separated out at high temperature; 6) no scale is produced on the surface of the die-casting cavity. The cleaning of the casting is heavy work, and the workload of the cleaning is usually 10-15 times of that of the die casting. Therefore, it is important to mechanize and automate the casting cleaning operation as the productivity of the die casting machine increases and the throughput increases. Pressure casting usually has two forms, one is that a die casting machine injects metal into a die by means of a piston to mold and crystallize, which is called die casting for short. The method can produce various small castings with accurate size, compact crystallization, small machining allowance, smooth surface and higher mechanical property than common die castings. It is suitable for non-ferrous metal, carbon steel, low alloy steel and high alloy steel die castings. In the former Soviet Union, billets weighing 80kg were produced by this method. Another type is a casting process which uses gas (such as compressed air, etc.) to pressurize on the metal liquid surface, so that the metal liquid enters the mold through a riser tube to be crystallized into a blank (or a casting). Low-pressure casting is also known because of the low pressures used. The low-pressure casting process includes the steps of putting the molten iron (steel) ladle in a sealed pressure tank, and then covering the pressure tank with a cover with a liquid-lifting tube (which may be also arranged at the lower part of the pressure tank), pressing and sealing. Then compressed air is introduced into the pressure tank, and the pressure tank is quickly pressurized, so that the molten metal stably rises through the liquid lifting pipe and enters the die cavity. The mold generally forms an angle of 120 to 400 degrees with the horizontal. The low-pressure casting is mainly used for aluminum alloy and copper alloy castings. The copper alloy ship rudder, the large copper alloy propeller (with the weight of 30t) and the nodular cast iron crankshaft and the cast steel crank throw for the large diesel engine in the large continuous shipbuilding factory in China are all cast by low pressure, and the quality is good. The invention provides a low-pressure casting process of a nickel-phosphorus alloy casting, which has the advantages of improving the casting precision, reducing machining work, reducing cost, saving energy consumption, prolonging the service life and being convenient to use.

The scope of the present invention is not limited to the specific embodiments of the present invention, and any changes or substitutions that may be made by one skilled in the art without departing from the spirit of the present invention are intended to be included within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope defined by the claims.