1. Casting:
1. Casting: The metal is smelted into a liquid that meets certain requirements and poured into the mold. After cooling, solidification, and cleaning, the predetermined shape is obtained. The process of shaping castings (parts or blanks) in terms of shape, size and performance. The basic technology of modern machinery manufacturing industry.
2. The cost of the blank produced by casting is low, and it can show its economy even more for parts with complex shapes, especially those with complex inner cavities; at the same time, it has wide adaptability and good performance. comprehensive mechanical properties.
3. However, the materials (such as metal, wood, fuel, modeling materials, etc.) and equipment (such as metallurgical furnaces, sand mixers, molding machines, core making machines, shakeout machines, etc.) required for casting production There are many shot blasting machines, cast iron flat plates, etc.), and they will produce dust, harmful gases and noise and pollute the environment.
4. Casting is the earliest metal thermal processing technology mastered by humans, with a history of about 6,000 years. In 3200 BC, copper frog castings appeared in Mesopotamia. Between the 13th and 10th centuries BC, China has entered the heyday of bronze castings, and the craftsmanship has reached a very high level, such as the 875-kilogram Simuwu Square Ding from the Shang Dynasty, Zeng Hou Yizun Pan from the Warring States Period, and the Western Han Dynasty's Translucent mirrors are all representative products of ancient casting. Early casting was greatly influenced by pottery. Most of the castings were tools or utensils for agricultural production, religion, life, etc., with strong artistic color. In 513 BC, China produced the earliest iron casting in the world recorded in writing - the Jin Dynasty cast tripod (approximately 270 kilograms in weight). Around the 8th century AD, Europe began to produce cast iron parts. After the Industrial Revolution in the 18th century, castings entered a new era of serving large industry. In the 20th century, casting developed rapidly. Ductile cast iron, malleable cast iron, ultra-low carbon stainless steel, aluminum-copper, aluminum-silicon, aluminum-magnesium alloy, titanium-based, nickel-based alloy and other cast metal materials were developed, and the invention of gray A new process for inoculating cast iron. After the 1950s, new processes such as wet sand high-pressure molding, chemically hardened sand molding and core making, negative pressure molding, and other special castings and shot blasting appeared.
5. There are many types of castings, which are customarily divided according to the modeling method: ① Ordinary sand casting, including green sand molds, dry sand molds and chemically hardened sand molds. ②Special casting, according to the modeling materials, can be divided into special castings with natural mineral sand and gravel as the main modeling materials (such as investment casting, mud casting, foundry workshop shell casting, negative pressure casting, solid casting, ceramic mold casting etc.) and special castings with metal as the main casting material (such as metal mold casting, pressure casting, continuous casting, low pressure casting, centrifugal casting, etc.).
6. The casting process usually includes: ①Preparation of casting molds (containers that turn liquid metal into solid castings). Casting molds can be divided into sand molds, metal molds, ceramic molds, clay molds, and graphite molds according to the materials used. etc., can be divided into disposable type, semi-permanent type and permanent type according to the number of uses. The quality of mold preparation is the main factor affecting the quality of castings; ② The melting and pouring of cast metals. Cast metals (cast alloys) mainly include cast iron, Cast steel and cast non-ferrous alloys; ③ Casting processing and inspection. Casting processing includes removing foreign matter on the surface of the core and castings, removing pouring risers, shoveling burrs and seams and other protrusions, as well as heat treatment, shaping, anti-rust treatment and rough machining wait. Imported pump valves
2. Forging:
1. Forging: It uses forging machinery to exert pressure on metal blanks to cause plastic deformation to obtain certain mechanical properties and a certain shape. and processing methods for dimensional forgings.
2. One of the two major components of forging. Through forging, the as-cast metal looseness and welding holes can be eliminated. The mechanical properties of forgings are generally better than castings of the same material. For important parts in machinery with high loads and severe working conditions, forgings are mostly used, except for simple shapes that can be rolled plates, profiles or welded parts.
3. Forging can be divided according to the forming method: ①Open forging (free forging). Impact force or pressure is used to deform the metal between the upper and lower anvils (anvils) to obtain the required forgings. There are two main types of manual forging and mechanical forging. ② Closed mode forging. The metal blank is compressed and deformed in a forging die chamber with a certain shape to obtain forgings, which can be divided into die forging, cold heading, rotary forging, extrusion, etc. According to the deformation temperature, forging can be divided into hot forging (the processing temperature is higher than the recrystallization temperature of the blank metal), warm forging (lower than the recrystallization temperature) and cold forging (normal temperature).
4. The forging materials are mainly carbon steel and alloy steel of various components, followed by aluminum, magnesium, titanium, copper, etc. and their alloys. The original states of materials include bar stock, ingot, metal powder and liquid metal, etc. The ratio of the cross-sectional area of ??the metal before deformation to the die cross-sectional area after deformation is called the forging ratio. The correct choice of forging ratio has a lot to do with improving product quality and reducing costs.