Cross wedge rolling (Transverse Rolling Mill) is a new rolling technology which appeared in 1961. It is suitable for rolling rotating body with variable section.

Two rolls with wedge-shaped pass rotate in the same direction along the forward direction of the wedge to gradually roll the billet into a rotating body with variable section.

The wedge hole is composed of wedging, forming and finishing three sections.

After finishing the section is equipped with a cutting knife, the roll can be rolled one piece or a pair of each turn.

The function of the cutter is to cut off the feed head or to separate a pair of rolled pieces into two pieces

History

As early as in the 19th century, people discussed the use of cross wedge rolling to produce shaft parts.

Czechoslovakia first used this process and equipment in industrial production in 1961.

In 1967, the GDR exhibited their plate wedge rolling technique at the International Fair in Leipzig and won the prize.

Since 1960s, a lot of research work has been done on this process and equipment in China, and the cross wedge rolling technology has been applied to the production of tools such as wrenches and shaft parts.

Many countries in the world use cross wedge rolling technology to produce hundreds of shaft parts and their blanks.

In the middle of 1960s, after the advent of two-roll cross wedge rolling, many countries have carried out a more extensive research work on three-roll cross wedge rolling.

In the 1970s, the three-high cross wedge rolling mill and its products appeared.

Since the early 1970s, China has studied the technology of three-high cross wedge rolling, and successfully rolled the hollow solid shaft parts such as railway wagon axle and motor shaft, and designed the large, medium and small three-high cross wedge rolling mill, and won the Eureka International Gold Award for invention in 1987.

Principle

A metal process in which variable section stepped shafts or blanks are produced by cross rolling on equipment (rolling mills) with wedge-shaped die rolls.

There are three types of cross wedge rolling (Figure 1) : flat wedge rolling is to achieve deformation between two identical and parallel flat surfaces moving in a straight line;

Roller cross wedge rolling is to realize deformation between two or three parallel roller surfaces, which have the same diameters and rotate in the same direction at the same speed.

Deformation is achieved between the surfaces of the single roll round rolls.

Under the rolling of the wedge die (deformation wedge), the blank of the round bar rotates and deforms at the same time. The diameter decreases while the length increases, and the blank is processed into a stepped shaft with variable section.

One or more products can be produced for each cycle of tool action.

Cross wedge rolling of shaft parts can be single rolling, or continuous rolling of long blank.

Continuous rolling, when a product is rolled, it can be cut off and thrown out by the shear wedge or blade installed after the deformation wedge, and then continuously sent into the blank to roll the next product.

Cross wedge rolling can be hot rolling can also be cold rolling, but mostly hot rolling, small diameter shaft parts can achieve cold rolling.

Cross wedge rolling can produce a variety of solid or hollow stepped shaft parts.

The step part can be cylindrical, conical or spherical, can be single step, multi-step and vertical step, and can roll out transverse groove, knurling, etc.

This process can not only produce rough parts, but also supply the blank for further plastic processing, and can realize the finish machining with little or no chip.

Cross wedge rolling features:

Compared with traditional forging or cutting processes, cross wedge rolling has the following advantages:

High production efficiency, usually 5-20 times of other processes.

If the geometry of the product is not too complex, a pair of parts can be machinedat a time using a symmetric die.

In practice, the roll speed is usually 10-30rpm, so at least 10-30 pieces can be rolled per minute.

High material utilization rate.

Typically, about 40% of the material is wasted in the form of chips in conventional machining (e.g. cutting), while 10% to 30% of the material is wasted in cross wedge rolling depending on the shape of the product.

The quality of the products is good.

The metal fiber streamline of cross wedge rolled piece is continuously distributed along the shape of the product, and the grain is further refined, so its comprehensive mechanical properties are better and the product accuracy is also high.

The working environment has been improved.

Because the cross wedge rolling process has no impact, low noise, and does not need the use of coolant, so the working environment has been greatly improved.

High degree of automation.

Rolled pieces from forming, surface finishing to the final product are automatically completed by the machine, the operator is less required.

limitations

The versatility is poor, can only produce circular section of shaft parts, need special equipment and mold;

Mold design, manufacturing, and production process adjustment is more complex, and the mold size is large.

Therefore, this process is suitable for mass production of shaft parts, but not suitable for small batch production.

In addition, large pieces cannot be rolled, and the length of rolled bars is limited.

Therefore, PR needs to innovate and improve the design method, expａnd the application range of cross wedge rolling, and give full play to the capacity of the existing rolling mills