paper machine press section – Paper machinery-paper making machine,paper manufacturing machinery

Vacuum Roll

webadmin — Mon, 17 Nov 2025 13:11:43 +0000

It includes Vacuum Press Roll, Vacuum Pickup Roll, and Vacuum Couch Roll,etc.

The vacuum roll is a key dewatering and sheet-handling component used in the forming and press sections of the paper machine. It is designed with a precision-drilled stainless steel or nickel-alloy shell, featuring thousands of uniform suction holes and an internal vacuum box system. The roll operates under controlled vacuum pressure to enhance water removal, sheet transfer, and web stability at high speeds.

Vacuum Press Roll

The vacuum press roll is used in the press section to increase sheet dryness before entering the drying section. By applying vacuum inside the roll shell, water is extracted more efficiently during the nip, improving dryness, reducing rewetting, and lowering steam consumption. The roll is equipped with a heavy-duty bearing system and is dynamically balanced for smooth operation.

Vacuum Pickup Roll

The vacuum pickup roll is located at the end of the forming section and plays a critical role in transferring the wet sheet from the forming fabric to the press felt. The vacuum zone ensures stable sheet pickup without sheet breaks, even at high machine speeds. The roll’s suction area and hole pattern are optimized to minimize marking and improve sheet formation.

Vacuum Couch Roll

The vacuum couch roll is positioned in the latter part of the forming section, where it provides final dewatering before the sheet leaves the wire section. High vacuum levels remove additional water from the web, improving sheet dryness and formation uniformity. The shell is engineered with corrosion-resistant materials and precise hole geometry to ensure long-term stability and consistent vacuum performance.

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Press Roll

webadmin — Mon, 17 Nov 2025 12:28:46 +0000

The press roll is a key component of the press section, designed to remove water from the wet paper web through mechanical pressure. It consists of a high-strength forged steel shell with optimized crown design to ensure uniform nip pressure across the full machine width. The roll surface is precision-ground to achieve excellent smoothness and dimensional accuracy, ensuring stable operation at high machine speeds.

The internal structure includes a high-efficiency water removal system, such as drilled blind holes or suction chambers (depending on roll type), which enhances dewatering performance and reduces sheet rewetting. Heavy-duty spherical roller bearings and a robust shaft design ensure long service life under continuous load. Dynamic balancing is performed according to G1.6 (or G2.5) standards to guarantee vibration-free running at operating speeds.

The press roll provides consistent nip loading, improved sheet dryness, and contributes to energy savings in the drying section, making it a critical component for high-quality paper production.

Press Section

webadmin — Wed, 17 Oct 2018 19:24:47 +0000

The task of the press section is to continue to remove water from the pulp fibers and to smooth the surface characteristics of the felt and wire sides ( top and bottom sides ) of the paper web running the length of the machine. Various types of press section can be made based on the requirement.

Jumbo press: roll diameter up to 1500mm

Shoe press

Four-roll & Three-nip Press

Pressure: up to 1300kg/cm

Press section of paper machine

webadmin — Sun, 10 Jun 2018 04:56:50 +0000

The second section of the paper machine is the press section, which removes the much of the remaining water via a system of nips formed by rolls pressing against each other aided by press felts that support the sheet and absorb the pressed water. The paper web consistency leaving the pres section can be above 40%.
Pressing is the most efficient method of dewatering the sheet as only mechanical action is required. Press felts historically were made from wool. However, today they are nearly 100% synthetic. They are made up of a polyamid woven fabric with thick batt applied in a specific design to maximise water absorption.
Paper machine Presses can be single or double felted. A single felted press has a felt on one side and a smooth roll on the other. A double felted press has both sides of the sheet in contact with a press felt. Single felted nips are useful when mated against a smooth roll (usually in the top position), which adds a two-sidedness making the top side appear smoother than the bottom. Double felted nips impart roughness on both sides of the sheet. Double felted presses are desirable for the first press section of heavy paperboard.
Conventional roll presses are configured with one of the press rolls is in a fixed position, with a mating roll being loaded against this fixed roll. The felts run through the nips of the press rolls and continues around a felt run, normally consisting of several felt rolls. During the dwell time in the nip, the moisture from the sheet is transferred to the press felt. When the press felt exits the nip and continues around, a vacuum box known as an Uhle Box applies vacuum (normally -60 kPa) to the press felt to remove the moisture so that when the felt returns to the nip on the next cycle, it does not add moisture to the sheet.
Some grades of paper use suction pick up rolls that use vacuum to transfer the sheet from the couch to a lead in felt on the first press or between press sections. Pickup roll presses normally have a vacuum box that has two vacuum zones (low vacuum and high vacuum). These rolls have a large number of drilled holes in the cover to allow the vacuum to pass from the stationary vacuum box through the rotating roll covering. The low vacuum zone picks up the sheet and transfers, while the high vacuum zone attempts to remove moisture. Unfortunately, at high enough speed centrifugal force flings out vacuumed water, making this less effective for dewatering. Pickup presses also have standard felt runs with Uhle boxes. However, pickup press design is quite different, as air movement is important for the pickup and dewatering facets of its role.
Crown Controlled Rolls (also known as CC Rolls) are usually the mating roll in a press arrangement. They have hydraulic cylinders in the press rolls that ensure that the roll does not bow. The cylinders connect to a shoe or multiple shoes to keep the crown on the roll flat, to counteract the natural “bend” in the roll shape due to applying load to the edges.
Extended Nip Presses (or ENP) are a relatively modern alternative to conventional roll presses. Paper machine top roll is usually a standard roll, while the bottom roll is actually a large CC roll with an extended shoe curved to the shape of the top roll, surrounded by a rotating rubber belt rather than a standard roll cover. The goal of the ENP is to extend the dwell time of the sheet between the two rolls thereby maximising the dewatering. Compared to a standard roll press that achieves up to 35% solids after pressing, an ENP brings this up to 45% and higher delivering significant steam savings or speed increases. ENPs densify the sheet, thus increasing tensile strength and some other physical properties.

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