Doctor

Doctors are used for cleaning of rolls and cylinders in paper machines. Each doctor is specially constructed to fit an actual application in a PM so that it meets all given requirements - mainly the roll cleaning. Therefore it is not possible to relocate it to other positions, since its function would be violated which may lead even to a roll damage.

Doctor types:

• cleaning
• creping
• breaking

Design

Doctors are usually delivered with blades and blade holders from well-known producers or according to customer's request. The main emphasis is put on overall functionality and also on a final price.

The doctors are delivered with a blade loading:

• by their own weight and manual control
• using pneumatic cylinders
• using hose blade holders

To improve the scraping effect, the doctors are equipped with an oscillation device. The movement is usually created by an eccentric pin which is located in the electric motor with a gearing device. The device can be delivered with a lubrication tube as well.

Main parts

• doctor beam (1)
• blade holder (2)
• blade (3)
• pins + bedding (4)
• PM fixing consoles (5)

Material

• fully stainless steel version (the wet part of the machine)
• stainless steel parts + covered carrier
• common steel, including anticorrosive paint (the dry part of the machine).

The material quality depends on customer's request or is made in a standard way of stainless steel and common steel. An oscillating electric motor can be delivered with a protection up to IP 68, pneumatic control cylinders are made of standard aluminum or non-corroding steel.

Accessories

• frequency converter

Scope of delivery

• construction design + devices according to main parts description
• parts for overall control elements connection for the PM control
• independent control panel

Advantages

• efficient and economic scraping function
• elimination of damage roll surface
• longer intervals for regrinding of roll surface

Control of doctors

Doctors are supplied with a blade loading by their own weight and manual control or with a loading and shifting by pneumatic cylinders. In case of doctors with hose holders, their loading and shifting are induced by means of air distribution hoses along the whole blade length. These hoses are an integral part of every doctor construction. Doctors with down pressure and shifting by means of pneumatic cylinders or doctors with hose holders, are coupled with a control box or a control panel of the paper machine. The control is done manually by pneumatic distributor and the setting of required pressure control by a reduction valve in accordance with data chart on the control box.

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