A riser pipe for low-pressure cast steel and its preparation method

Abstract

The invention belongs to the technical field of low-pressure casting and particularly relates to a riser pipe for low-pressure steel casting and a manufacturing method thereof. The riser pipe for low-pressure steel casing is provided with an outer pipe body (2) made of heat-resistant steel and an inner pipe body (4) made of heat-resistant steel, wherein an annular gap exists between the outer pipe body (2) and the inner pipe body (4). Multiple layers of hollow rivets (5) are welded to the outer wall surface of the outer pipe body (2) in the vertical direction, and multiple layers of hollow rivets (5) are welded to the inner wall surface of the inner pipe body (4) in the vertical direction. Fused silica castable materials are arranged on the outer wall surface of the outer pipe body (2), the inner wall surface of the inner pipe body (4) and the inner wall surface of a through hole in a heat-resistant steel disc (1) in a combining mode to serve as refractory materials (1). An opening in the lower end of the annular gap between the outer pipe body (2) and the inner pipe body (4) is sealed through a plug (7). According to the riser pipe for low-pressure steel casting and the manufacturing method thereof, the problem that the refractory materials on the inner wall and the outer wall crack due to heat expansion is solved, and the heat preservation performance and the thermal shock resistance of the riser pipe are improved.

Description

Technical field [0001] The invention belongs to the technical field of low pressure casting, and specifically relates to a riser tube for low pressure cast steel and a preparation method thereof. Background technique [0002] Low-pressure casting is a casting method between gravity casting and pressure casting. Its purpose is to solve the contradiction between filling and feeding of the gating system in gravity casting. In the gravity casting, in order to fill the mold smoothly and avoid air holes and slag inclusion, the bottom injection type is generally used, and the temperature field distribution in the mold is not conducive to feeder feeding. Low-pressure casting has absorbed the advantages of the smooth filling of the bottom in the gravity casting and the crystallization and solidification of the casting under pressure in the pressure casting. It cleverly uses the air pressure in the crucible to fill the mold from the bottom up with the molten metal and maintain the runner u...

AI Technical Summary

Problems solved by technology

[0004] Patent CN1039984A relates to an integrally poured composite riser. Its structural feature is that the steel pipe is used as the framework for load-bearing and gas leakage prevention. The inside and outside of the steel pipe is poured with high-aluminum cement combined with refractory castables; It is delivered to use after drying at medium temperature; before use, it needs to be heated and baked, and after use, it needs to be cooled and baked; the riser is not only suitable for low-pressure casting of ferrous metals such as cast iron and cast steel, but also for non-ferrous metals such as cast aluminum and cast copper. Low-pressure casting of metals; however, in this patent, the high-alumina cement-bonded refractory castables inside and outside the steel pipe are casted, and the porosity is ≥ 17%. Gas can easily pass through the interface between the steel material and the high-alumina cement-bonded refractory castable when pressurized Into the inner wall of the riser or into the mold; due to the mismatch between the thermal expansion properties of the steel material and the high-alumina cement-bonded refractory castable, it is easy to cause the high-alumina cement-bonded refractory castable to crack when heated at high temperature; at the same time, due to the high-alumina cement Cement-bonded refractory castables have poor heat resistance, high bulk density, and poor thermal insulation performance. Therefore, the composite riser needs to be baked at 400 ° C to 500 ° C during the preparation process, and it needs to be pre-baked before die-casting. It needs cooling and baking, which makes the process relatively complicated

Images