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Product description
Doctors are used for cleaning of rolls and cylinders in paper machines. They are usually supplied with blade holders BONETTI, designed for blades 75 mm wide. The blades widths are not to be applied to holders intended for creping doctors of drying and glazing cylinders where the holders are installed with special design for more frequent replacements of blades. In addition to standard blade holders, type BONFIRM K 35 A, doctors are installed in some PM places also together with highly flexible holders, type MAXIFLEX or BONFIFLEX. Optionally, doctors can be supplied with other types of holders or with holders from other manufacturers.
Design
Every doctor is designed only for a special application and PM modification and therefore it is not possible to displace it from one position in the other due to changed structural criteria of the given doctor beam. To improve their scraping efficiency these doctors can be equipped with oscillating equipment. Their shifting is provided with an electric geared motor.
A doctor consists of welded consoles mounted in a relevant place of the paper machine. On these consoles there is a beam fitted with bearing housings that allow free pivoting of beam and in case of swinging doctors also its axial displacement of 19 mm at least. On the beam there is an own blade holder in which a doctor blade is fixed. The blade beam can be equipped with a wide assortment of bearings that differ from each other in design according to type and size of doctor.
Machine design and work safety are in compliance with EU standards.
Main parts
- supporting consoles (1)
- beam with bearings (2)
- blade holder (3)
- blade (4)
Accessories
- pneumatic control
Scope of delivery
- machine according to main parts description
- accessories optionally
Material
All parts, except of beam, are made of stainless steel 1.4404 or 1.4435. Doctor beam is made of structural steel St 37 and coated with stainless plates, or it can be made only of stainless steel 1.4404 or 1.4435. In case of electromechanical oscillation is electric motor provided with protection rate IP 55 and corrosion prevention KS 1.
For PM dry part:
All parts are made of structural steel St 37 protected with coating. Jointing elements are supplied with anticorrosive coating (usually zinc plating). In case of the electromechanical oscillation for PM drying part is electric motor provided with protection rate IP 54, with thermal protection H and motor winding protection against moisture and acid vapours.
Control of doctors
Doctors are supplied with down-pressure of blade by own weight and manual control or with down-pressure and shifting by means of pneumatic cylinders. In case of doctors with holders, type MAXIFLEX or BONFIFLEX, their down-pressure and shifting are induced by means of air distribution hoses along the whole blade length. These hoses are an integral part of every doctor supply. Doctors with down-pressure and shifting by means of pneumatic cylinders or doctors with holders, type MAXIFLEX or BONFIFLEX, are coupled with a control box or a control board of the paper machine. The own control is to be done manually by means of a pneumatic distributor and setting of required pressure value by a governor valve in accordance with data shown in a chart on the control box.
Advantages
- efficient and economic scraping function
- elimination of contingent damage of roll surface
- longer intervals for regrinding of roll surface
Technical parameters
Oscilating doctor with pneumatic down-presure and tilting of bottom and top drying cylinder with diameter of 1500mmExample of doctors installation in paper machine
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