Tissue Machine Roll Doctors
A doctor is a mechanical device designed to maintain a blade in a fixed position under uniform pressure against a roll surface. Doctors are used in all sections of a tissue machine to remove excess water and contaminants from roll surfaces, and in some applications, to remove the sheet from roll surfaces on sheet breaks or during sheet threading. Most tissue machines also have creping doctors to remove the sheet from the Yankee dryer.
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Course Details
Learning Objectives
• Identify the two main functions of tissue machine roll doctors
• Identify the components of a doctor
• Identify the purpose of the doctor components
• Distinguish between mechanically-adjusted and self-conforming blade holders
• Identify where roll doctors are typically installed on tissue machines
• State why doctors and doctor blades should be regularly inspected
Specs
Frequently Asked Questions
Why are flexible, self-conforming doctor blade holders used on some rolls?
Why should you avoid increasing the load on a used doctor blade?
Why is it important to change doctor blades on a regular basis?
Where are air doctors used?
Why do doctor blades oscillate?
Sample Video Transcript
On tissue machines, doctors are typically installed on the breast roll, forming roll, and various wire rolls in the forming section, on the suction pressure roll and felt rolls, or on rolls in the through air drying section, on the Yankee, and on the reel drum. In the forming and press sections, doctors are often accompanied by roll showers to provide lubrication and help clean the roll surfaces. Deflectors and saveall trays are often installed to help direct the white water and any contaminants removed from the rolls away from the sheet and fabrics.
