Casting flange has accurate blank shape and size, small processing volume and low cost, but has casting defects (pores, cracks and inclusions); The internal structure of the casting is less streamlined (if it is a cutting piece, the streamline is even worse); Forged flanges generally contain less carbon than cast flanges and are less prone to rusting. Forgings are streamlined and compact, and their mechanical properties are better than cast flanges. Improper forging process will also lead to large or uneven crystal grains, hardening cracks and higher forging cost than cast flanges.
Forgings can withstand higher shear and tensile forces than castings. The advantages of the casting are that it can produce a more complicated shape with lower cost. And has uniform internal structure and no harmful defects such as air holes, inclusions and the like of castings; Foundry flanges and forged flanges are distinguished from each other in terms of production process, for example, centrifugal flanges are one kind of casting flanges.
Centrifugal flange belongs to precision casting method. Compared with ordinary sand casting, this casting method has much finer structure and much higher quality, and is not prone to problems such as loose structure, porosity, trachoma, etc.
Production Process of Forging Flange
Selecting high-quality billet for blanking, heating, forming and cooling after forging. The forging process includes free forging, die forging and die forging. During production, different forging methods are selected according to the forging quality and production batch.
Basic process of free forging: during free forging, the forging shape is forged step by step through some basic deformation processes. The basic processes of free forging include upsetting, drawing, punching, bending and cutting.
Upsetting is an operation process of forging the original blank along the axial direction to reduce its height and increase its cross section. This process is often used for forging gear blanks and other disc-shaped forgings. Upsetting is divided into full upsetting and partial upsetting.
Pulling is a forging process that increases the length of the blank and reduces its cross section. It is usually used to produce shaft blanks, such as lathe spindles and connecting rods.
A forging process in which a punch is used to punch through holes or blind holes in a blank.
The forging process of bending the blank to a certain angle or shape.
A forging process in which one part of the blank is rotated by a certain angle relative to the other part by twisting.
Forging process of cutting and dividing blank or cutting material head.
Die forging is all called model forging, and the heated blank is placed in a forging die fixed on die forging equipment for forging and forming. Basic working procedures: blanking, heating, pre-forging, final forging, punching and connecting skins, trimming, tempering and shot peening. Common processes include upsetting, drawing, bending, punching and forming. Common die forging equipment Common die forging equipment include die forging hammer, hot die forging press, flat forging machine and friction press, etc. Generally speaking, forged flanges are of better quality and are generally produced by die forging. They have fine crystal structure and high strength. Of course, they are also more expensive.
The inner and outer diameter and thickness discs of the flange with processing capacity are directly cut out on the middle plate, and then bolt holes and waterlines are processed. The flange produced in this way is called cut flange, and the maximum diameter of such flange is limited to the width of the middle plate.
The process of cutting strips with a middle plate and then coiling them into circles is called coiling, and is mostly used in the production of some large flanges. After successful coiling, welding is carried out, then flattening is carried out, and then waterline and bolt hole processing is carried out.