DST Holder

A high performance holder providing precise doctoring with consistent and uniform distribution of blade loading.

Features/Benefits

Precise blade-to-roll fit from pneumatic pressure results in longer blade life.
Significantly reduces downtime for blade or roll maintenance.
Separate loading fingers for even distribution of loading pressure across the roll face–provides improved doctoring.
Fingers are of cast stainless steel for better corrosion resistance and retainment of shape.

Flexibility with Control

The Kadant Web Systems range of DST holders is designed for high performance doctoring in a variety of paper machine roll positions, with a remarkably low rate of blade consumption. Pneumatic pressure provides balanced blade pressure across the roll face at all times during operation. By balancing blade-to-roll pressure and assuring a precise fit, the DST Doctor affords longer blade life, which reduces downtime necessary for blade and roll maintenance. To maintain optimum doctoring during changes in machine operating conditions, loading pressures can be adjusted through the pressure-regulating panel. Air Loading cylinders are an available option to open the doctor from the roll.

Holder Construction

Kadant Web Systems' DST holders are constructed of stainless steel with either graphite or stainless loading plates, and are ruggedly built to give dependable operation under a range of difficult conditions. On applications such as breast rolls, press rolls, breaker stack rolls, first and last dryers, sweat dryers, bottom, intermediate and top calender rolls and reel drums, DST holders have compiled an impressive record for economical operation. Loading fingers, constructed of cast stainless steel for better corrosion resistance, are manufactured with blade retaining grooves. Blade tabs facilitate either front or end removal.

Precision Blade Pressure Conti

Two pneumatic pressure tubes run the full length of the holder–the load tube which provides precise, uniform and adjustable control to the blade, and the unload tube which is used to lift the holder for blade changing. The tubes rest against loading fingers, mounted on 2-inch centers on a pivot rod. A flexible stainless steel or graphite loading plate connects all fingers in the holder. The doctor blade is inserted between the loading plate and stainless steel fingers. During operation, pneumatic pressure is applied to the loading tube, which actuates the fingers and transfers pressure to the blade tip. With the inherent flexibility of the top plate supported by separate loading fingers, the loading pressure is distributed evenly across the roll face through the doctor blade, which conforms exactly with the roll surface. This results in greatly improved doctoring over conventional holders where the surface to be doctored may be irregular or subject to variable crowns. To lift the blade from the roll, pneumatic pressure is released from the loading tube into the unloading tube, pivoting the top plate assembly away from the roll face.

Converting Existing Doctors

Kadant DST blade holders can be supplied with an adapter assembly to convert existing doctors. We recommend an evaluation of each conversion, since doctor stability is crucial. THE SMART DST DOCTOR® Provision for monitoring blade load (PLI) is provided by fitting load cells under the base of the turnbuckles or air cylinders. A separate instrument panel will show a digital readout of blade loading.

The Smart DST Doctor®

Provision for monitoring blade load (PLI) is provided by fitting load cells under the base of the turnbuckles or air cylinders. A separate instrument panel will show a digital readout of blade loading.

Pneumatic Circuitry

The pneumatic circuitry for operating DST holders directs filtered mill air through a four-way valve providing regulated air to the rear tube to load the blade to the roll. By turning the valve, air is directed to the front unloading tube. A control panel, which can be supplied separately, incorporates a special setup feature to simplify and reduce installation time. When the air is directed to the load tube, a second valve, located inside the panel, directs air simultaneously to the unload tube. This insures that the holder top plate is set parallel during set-up and alignment.