Continuous casting and forging production of high strength deformed aluminum alloy blank
Abstract: Extrusion die-casting die forging is a kind of continuous casting and forging technology. This paper introduces the technical realization principle of the multi-directional extrusion die-casting die forging process and equipment and mold. It points out the shortcomings of the one-way extrusion die-casting die forging process, and the problems of the traditional casting device clamping force resistance mechanism, especially for large forging. The development of equipment with pressure and high clamping force proposes a recommendation. The development trend of multi-directional extrusion die-casting die forging technology is introduced. It is believed that the continuous casting and forging process and equipment technology represented by extrusion die-casting die forging is die casting, low pressure (differential pressure, gravity) casting and semi-solid processing technology. The complex is an effective expression of the "mechanical foundation final forming process". Extrusion die-casting forging processes not only produce a variety of meltable metals, but have actually brought semi-solid processing from the laboratory technology to the forefront of industrial applications. The characteristics of semi-solid extrusion die-casting forging process of flame-retardant magnesium alloy were introduced, and the advantages of industrial economy were analyzed. The prospect of promoting the development of magnesium alloy casting and forging industry in China was predicted.
Because the tensile strength of ordinary hard aluminum alloy is between 380-450Mpa, it is almost double the tensile strength of ordinary cast aluminum alloy, and the strength of super-hard aluminum alloy can reach 600Mpa. Although the unit price of the deformed aluminum alloy is higher than that of the cast aluminum alloy, the forming cost is higher than that of the casting process, but since the product structure size can be significantly reduced, and further heat treatment strengthening, welding and surface anodizing treatment can be performed, the latter The cost performance is significantly higher than the former, so more and more occasions, I hope to use or change the production parts of deformed aluminum alloy. For the use of sports parts, such as airplanes, ships, automobiles and motorcycles, sports bicycles, etc., to reduce the energy saving efficiency and speed efficiency brought by the weight, the deformed aluminum alloy has an irreplaceable advantage.
Due to the remarkable progress of continuous casting and forging technology, the deformed aluminum alloy blank which is as complex as the structure of the die casting can be produced very easily and smoothly with similar workshop cost. Therefore, the use of deformed aluminum alloy instead of the traditional cast aluminum alloy production Rough, not only has an economic advantage, but has become a trend and trend.
1 Basic situation and performance comparison between cast aluminum alloy and deformed aluminum alloy
1.1 Industrial aluminum ingots are divided into two categories: cast aluminum alloys and deformed aluminum alloys. In general, cast aluminum alloys are suitable for producing aluminum castings by casting, while deformed aluminum alloys are suitable for producing aluminum products by pressure processing (extrusion and forging).
1.2 Deformed aluminum alloys include: rust-proof aluminum (LF), hard aluminum (LY), super-hard aluminum (LC), wrought aluminum (LD) and special aluminum (LT). Since the average comprehensive mechanical properties of deformed aluminum alloys are always higher than that of cast aluminum alloys (the forged properties of cast aluminum alloys are on average more than a few percent higher than their as-cast properties), many grades of deformed aluminum alloys can also pass quenching and aging. Other heat treatment methods are used to improve the mechanical properties. Therefore, industrial design is expected to apply more deformed aluminum alloys to meet the requirements of use.
1.3 Two factors limit the application of forged aluminum alloys or weaken its industrial economy:
First, the casting properties of the deformed aluminum alloy are very poor, and the liquid fluidity is generally only one-third of that of the cast aluminum alloy. It is difficult to produce a complicated structure blank by the conventional casting method.
Second, even if the deformed aluminum alloy blank is produced by the casting method, if the shrinkage shrinkage and the pore pinhole defects which are common in the casting process cannot be solved, the subsequent heat treatment and surface anodizing process cannot be continued.
The most fundamental reason is that the as-cast deformed aluminum alloy blank, even if its internal defects are eliminated, but the metallurgical grains are coarse and always dendritic, the performance after heat treatment is greatly reduced, or only similar to the performance of ordinary cast aluminum alloy. The use of this relatively expensive material variety has lost its economic significance. However, the emergence of continuous casting and forging technology has effectively changed this situation.
2 Introduction to continuous casting and forging technology
Continuous casting and forging technology, it refers to the same set of molds in the same equipment, continuous filling and forging production of the blank, its essence is a process technology realized by the function of equipment. Therefore, different continuous casting and forging equipment have different continuous casting and forging subdivision processes.
2.1 Continuous casting and forging equipment, according to the way of equipment placement, can be divided into horizontal and vertical, according to casting to soup, it is divided into cold chamber and hot chamber. Continuous casting and forging process, according to the number of forging pressure cylinders installed by equipment, can be divided into one-way continuous casting and forging and multi-directional continuous casting and forging two categories.
2.2 Two typical continuous casting and forging processes and equipment: one is invented by the Soviets, using liquid metal to complete the "liquid metal forging" (or "melting forging"), and the other is the use of China The "pressure casting die forging" (or "extrusion die casting die forging" - referred to as "die casting die forging" realized by the invention patent technology.
2.2.1 "Liquid metal die forging" process and equipment technology For the "liquid metal die forging" process, although we can not clearly see its obvious "casting" - "forging" separate process, but this is done with a hydraulic press The nature of the process can still be classified as one of the continuous casting and forging processes. It is also a kind of one-way continuous casting and forging process.
The "liquid metal forging" process completed by a hydraulic press can produce blanks that are not very complicated in structure and that do not require high axial dimensional accuracy of the blank.
Since the hydraulic press is a versatile universal device, even with a double-motion beam hydraulic press, it still has only three power heads. Therefore, it is difficult to complete a multi-power head and a continuous composite sporting attitude. Casting and forging process. In addition, it has no filling mechanism, and complex blanks cannot be produced at all.
In the production practice, the process completed with this equipment has low production efficiency and poor industrial economy. Due to the lack of technological means, workers need to operate close to the high temperature molds and blanks at close range, which not only has high labor intensity, but also does not meet the requirements of modern industrial safety and civilized production. The insufficiency of the process means that this production process relies too much on the operator's skills, making the process repeatability and reliability low, and it can no longer meet the advancement requirements of industrial production.
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