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Method for applying fluctuating pressure in low-pressure casting process

A low-pressure casting and pressure technology, which is applied in the field of special forming of non-ferrous alloys, can solve problems such as shrinkage cavities and porosity, and achieve the effects of improving feeding capacity, promoting feeding range, and eliminating shrinkage cavities and porosity defects

Inactive Publication Date: 2016-02-24
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The present invention aims to solve the problem of shrinkage cavities and porosity defects in the existing large-scale aluminum-copper alloy castings during the low-pressure solidification process, and provides a method for applying fluctuating pressure during the low-pressure casting process

Method used

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  • Method for applying fluctuating pressure in low-pressure casting process
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  • Method for applying fluctuating pressure in low-pressure casting process

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specific Embodiment approach 1

[0011] Specific implementation mode 1: The method for applying fluctuating pressure in the low pressure casting process of this embodiment is carried out according to the following steps:

[0012] When low-pressure casting is performed on alloy castings, when the alloy castings complete the lifting phase, filling phase, and pressurization phase, enter the pressure holding phase to apply fluctuating pressure to maintain the pressure. After the pressure is maintained until the casting is completely solidified, the fluctuating pressure is unloaded to complete the low pressure Casting.

[0013] The fluctuating pressure described in this embodiment controls the pressure during the holding and solidification period by controlling the pressure increase valve and the pressure relief valve.

specific Embodiment approach 2

[0014] Specific embodiment two: this embodiment is different from specific embodiment one in that: the method of applying fluctuating pressure is: the frequency f of applying fluctuating pressure is 1Hz-50Hz, and the fluctuating pressure range of the pressure holding stage is p~y, so The p is the lower limit of the fluctuating pressure, which is the filling pressure at the end of the filling, and the p is calculated according to the formula p=Hρgμ, where H is from the liquid level in the crucible in the sealed pot after pouring to the highest point of the mold cavity of vertical Height, ρ is the density of alloy liquid, and the unit of ρ is kg / m 3 , Μ is the drag coefficient, g is the acceleration of gravity; the y is the upper limit of the fluctuating pressure, and its value is 0.05 MPa ~ 0.3 MPa. The upper and lower limits of the control fluctuating pressure remain unchanged, and the fluctuating pressure is applied until the end of the pressure holding stage, and the fluctua...

specific Embodiment approach 3

[0015] Specific embodiment three: This embodiment is different from specific embodiment one or two in that the method of applying fluctuating pressure is: the frequency f of applying fluctuating pressure is 1Hz-50Hz, and the fluctuating pressure range of the pressure holding stage is p~y ; The p is the lower limit of the fluctuating pressure, which is the filling pressure at the end of the filling, the p is calculated according to the formula p=Hρgμ, where H is from the liquid level in the crucible in the sealed tank to the mold cavity after pouring The vertical height of the highest point, ρ is the density of the alloy liquid, and the unit of ρ is kg / m 3 , Μ is the drag coefficient, g is the acceleration of gravity; the y is the upper limit of the fluctuating pressure, and its value is 0.05 MPa ~ 0.3 MPa; then the upper and lower limits of the applied fluctuating pressure are controlled, and as the number of cycles n increases, the fluctuating pressure The difference between th...

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Abstract

The invention relates to the technical field of special formation of non-ferrous alloy, particularly relates to a method for applying fluctuating pressure in a low-pressure casting process and aims at solving the problem that the existing large aluminum copper alloy casting forms shrinkage cavity and porosity defects in the low-pressure solidification process. The method comprises the steps of applying the fluctuating pressure to carry out a pressure maintaining stage after an alloy casting finishes a liquid lifting stage, a mold filling stage and a pressurizing stage when the alloy casting is subjected to low-pressure casting, and unloading the fluctuating pressure after the casting is completely solidified to finish low-pressure casting, wherein the time of the pressure maintaining stage is t, and the pressure maintaining time t ranges from pressure maintaining starting to complete casting solidification. The method is used for low-pressure casting.

Description

Technical field [0001] The invention relates to the technical field of special forming of non-ferrous alloys, in particular to a method for applying fluctuating pressure in a low-pressure casting process. Background technique [0002] Aluminum-copper alloys are widely used in aerospace, automotive, and mechanical industries because of their excellent mechanical properties at room temperature and high temperature. The wide crystallization range, greater wall thickness sensitivity, and poor casting performance of the alloy make large castings formed by low-pressure aluminum-copper alloy castings often prone to shrinkage porosity, shrinkage cavities, segregation and thermal cracking during the production process. Other casting defects have severely affected the development and application of this alloy. At the same time, large castings are often large in size and complex in structure, and are subjected to huge static loads and impact loads during work. This requires materials with ...

Claims

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Application Information

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IPC IPC(8): B22D18/04
CPCB22D18/04
Inventor 吴士平王晔陈伟王汝佳肖文峰蒋清张建兵
Owner HARBIN INST OF TECH
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