1. Cooling unit. The function of the cooling unit is to cool the shaped tubing to room temperature or near room temperature, thereby maintaining its set shape. There are two cooling methods: one is the immersion type, commonly used for small-diameter tubing; the other is the spray or mist type, typically employed for large-diameter tubing.

(1) Immersion-type cooling system. The immersion-type cooling system consists of a water tank, a support frame, inlet and outlet pipes, partitions, and sealing rubber rings. To create a temperature gradient along the pipe’s direction of travel, the water tank is divided into several compartments by partitions. The water level in the cooling tank is maintained, and circulating water helps to keep the water temperature stable. Both ends of the tank are sealed with rubber rings; each ring has a central opening that allows the pipe to pass through while preventing water from leaking out.

(2) Spray‑type and mist‑type cooling systems primarily consist of a water tank, spray nozzles, a support frame, and a tank cover. Their structure is similar to that of immersion‑type systems; the main difference is the inclusion of spray nozzles evenly distributed around the circumference of the pipe within the tank, which deliver water or water mist to cool the pipe. Compared with water spraying, mist cooling offers superior performance, as the mist nozzles atomize water into fine droplets that evaporate upon contact with the pipe surface, carrying away substantial amounts of heat and thereby significantly enhancing both the cooling efficiency and uniformity.

2. Pulling device. Its primary function is to overcome the various frictional resistances encountered by the pipe during cooling and sizing processes, advancing the pipe at a uniform speed and adjusting the pulling speed to accommodate pipes of different wall thicknesses. To this end, the drive system of the pulling device should be capable of variable-speed operation with a wide speed range. Currently, the three most common types of pulling devices are as follows:

(1) Roller-type traction device. It mainly consists of rollers, a frame, a roller‑spacing adjustment mechanism, and a transmission system. Typically, such a device includes 2 to 5 sets of traction rollers; the lower rollers are usually driven, while the upper rollers are idler rollers. To enhance traction friction, the lower drive rollers may also be rubber‑covered. The upper rollers can be adjusted vertically via the spacing‑adjustment mechanism to accommodate pipes of different diameters. They are pressed against the pipe being pulled with a specified force, and the roller diameter ranges from 50 to 150 mm, with adjustable traction speed. This type of traction device features a simple structure and convenient operation; however, due to the small contact area between the rollers and the pipe, its traction force is relatively limited, making it suitable only for pipes with diameters of 100 mm or less.

(2) Track-type traction device. It mainly consists of an adjustment handwheel, tracks, a frame, and a transmission system. Each track is fitted with sprockets at both ends; the right‑hand sprocket is driven by an electric motor. Traction on the pipe is achieved via the transmission mechanism. For pipes of different diameters, traction and clamping are adjusted by means of the upper handwheel and its associated transmission, which regulate the track tension. This device features a simple structure and convenient adjustment; however, its manual clamping force is relatively low, making it suitable primarily for small‑diameter pipes. For large‑diameter pipes, four or more tracks are typically employed, with the lower tracks capable of radial movement—either manually or mechanically—to accommodate various pipe sizes. Once properly adjusted, these lower tracks remain fixed. Meanwhile, the upper tracks are moved radially either manually or by pneumatic cylinders, and the clamping force is regulated by adjusting air pressure to secure or release the pipe.

Currently, most crawler-type traction devices are equipped with two tracks. The number of tracks depends on the diameter and wall thickness of the material being pulled. Some traction units may feature a greater number of tracks; in such cases, one selects only a few or all of them based on the pipe’s diameter and wall thickness. Typically, the tracks are fitted with a specified number of rubber clamping blocks, shaped as inward‑curving arcs to increase the contact area with the pipe. Clamping is usually accomplished by pneumatic or hydraulic cylinders. These traction devices can generate pulling forces ranging from 750 to 7500 N or even higher; their large contact area helps prevent deformation and slippage of the pipe, making them suitable for handling a wide variety of pipe materials and well‑suited for both thin‑walled and large‑diameter pipes.

3. Rubber‑belt traction device. The rubber‑belt traction device consists primarily of a rubber belt and its drive mechanism. It integrates cooling and traction functions, making it suitable for the traction and cooling of rigid or flexible tubes with diameters less than 25 mm. The tube is clamped between the rubber belt and a pressure roller, and the belt, driven by the transmission system, pulls the tube forward. This type of traction device generates relatively low pulling force; in some cases, two rubber belts—one above and one below—are employed to increase traction, but even then it remains applicable only to small‑diameter, thin‑walled tubing.