What Is Tube Swaging?

Die forging refers to a forging method in which a blank is formed by using a die on a special die forging equipment. Forgings produced by this method are accurate in size, have small machining allowances, and have complex structures and high productivity.

Used on a forging hammer or press

According to different equipment, die forging is divided into hammer forging,

For forging

HXN5 locomotive is a high-power diesel locomotive developed by a locomotive company and the United States GE Company. As one of the key parts of diesel engines, the connecting rods are imported and expensive. In 2012, the company introduced the PZS series 22,000-ton electric screw press produced by the German Miller-Vandikaden company, and localized the HXN5 locomotive diesel engine connecting rod. Part solid diagram, as shown in Figure 1. ^[3]

As a pipe joint, flange parts are widely used in construction, chemical industry, water supply and drainage, petroleum, fire protection, plumbing, shipbuilding and other fields because of their advantages such as flexible disassembly and assembly. The closed die forging process is used to precisely form small and medium-sized flange parts, which can save materials and have good forging performance. In mass production, it has the advantage of "more refined, cleaner, and more economical."

A type of 1Cr18Ni9 stainless steel flange parts for chemical pipelines used for conveying low-pressure gas. After comprehensive analysis of factors such as product structure, quality requirements, production batches, and forming characteristics, a closed die forging process is proposed to form this flange. Forgings to obtain better economic and social benefits, and enhance the market competitiveness of enterprises.

1 process analysis

The flange part diagram is shown in Figure 1. The maximum diameter of the flange part is 140mm, the total height is 55mm, and the center hole diameter is 50mm. The calculated part volume is 287950mm ³ and the mass is 2.25kg. For example, if 145mm × 60mm bar material is used for direct cutting, the material utilization rate is only 29.1%, and the processing volume is large. Due to the large production batches, in order to reduce production costs, it is a better manufacturing process to use die forging + cutting to produce the part. Considering the small part size, closed die forging technology can be adopted, and flange forgings can be precisely formed on the friction screw press of commonly used forging equipment, which can further reduce production costs.

The production process flow of this flange part is: blanking blank cleaning heating closed die forging punching skin pre-heat treatment machining final heat treatment. ^[1]

2 Formulation of closed die forging process

Drawing forgings

Eight 14 holes evenly distributed on the flange and 6mm × 4mm annular seal groove at the lower end. Due to the small size, it cannot be forged. It is filled with the remaining blocks and obtained in the later cutting process. Machining allowance, the lower end is 5mm in height. The parting surface is taken on the upper surface of the flange. After considering the machining allowances, forging tolerances, punching and skinning, the cold forged part shown in Figure 2 is drawn, and its volume is calculated to be 371951mm ³ .

Based on the size of the cold forging drawing and the shrinkage rate, a hot forging drawing is formed for the calculation of the tonnage of the equipment, the design of the forging die, and the manufacturing. ^[1]

3 mold working principle

The closed mold structure of the flange forging is shown in Figure 3. The mold frame uses the standard mold frame of a 1600t friction screw press. The lower mold 2 and the back baffle 7 and the inclined plate 5 are assembled on the inclined surface with a 15 ° inclination. The elbow wedge of the inclined plate is matched with the inclined groove of the lower die base 6 (inclination is 10 °). By tightening the screws 4, the lower die is fixed on the lower die base.

The side wall plate 9 and the screws 10 are used for lateral fastening and adjustment of the lower mold. The fixing method of the upper mold 1 and the upper mold seat is the same as above. The upper and lower die holders are fastened to the slide and work surface of the press with bolts, respectively. The guide post and guide sleeve are guiding and positioning devices, which guide the center of the upper mold and the lower mold to align. During closed die forging, the blank is placed in the lower die cavity, and the upper die applies pressure to the blank as the slide of the press moves down. In time, the blank just fills the mold cavity. The die forging is ejected by the ejector pin 8 and the forging process ends. ^[1]