Metal working – Method of mechanical manufacture – Roller making
Patent
1996-11-27
1999-08-24
Young, Lee W.
Metal working
Method of mechanical manufacture
Roller making
298953, B23C 302, B23C 328, B23D 100
Patent
active
059409690
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. FIELD OF THE INVENTION
The present invention is in the field of improving rotation of a rotating roll body.
2. DESCRIPTION OF THE BACKGROUND ART
It is prior known that the elastic asymmetry of a roll is caused by axially extending grooves, material variations, wall thickness variations in a tubular-bodied roll or ellipticity of a roll.
It is prior known to reduce the imbalance and dynamic deflection of a roll by the addition of material: by securing weights or mass to the ends or in the middle of a roll, by injecting material to the light side of the inner periphery of a tubular roll.
It is prior known to reduce the imbalance and dynamic deflection of a roll by the removal of material: by drilling holes in the jacket of a roll, by internally turning a roll to a constant wall thickness or by aligning a roll in the turning of an outer surface according to the centre axis of a bore.
The rolls may be coated. The coated roll consists of an axle and a coating element which can be made of a paper or fabric fiber or a synthetic material or a combination thereof. The coated rolls are used in paper industry for example as calender glazing rolls and as various guide rolls. It is prior known to secure the positive attachment of a coating by providing the fiber-coated calender glazing rolls with one or two grooves (as an adhesive injection duct) or with a spline.
SUMMARY OF THE INVENTION
The present invention relates to a method for reducing the elastic asymmetry and imbalance of a flexible rotor, such as a roll, by machining material off the outer surface or inner surface of the roll by means of axially extending grooves or pockets, as well as to an apparatus for internal machining according to the method.
As for the alignment of rolls, it has been found out e.g. by the Applicants that the rolls are generally elliptical even after a successful alignment. The ellipticity is at its peak in the mid-section of a roll, reducing towards the ends of a roll in proportion to the sag of a roll. The calender glazing rolls, which are provided with diametrally located, axially extending adhesive injection grooves, have typically a measurable, distinct, elliptical circularity profile, having a size of 15-30 .mu.m and an angle of 45.degree. relative to the grooves included in the axle. The grooves cause elastic asymmetry which appears in the motion of the rotational centre axis of a roll in the form of two rotations as the roll does a single rotation. In machining, this results in an elliptical circularity profile as the turning tool remains stationary. In a calender, the elliptical rolls subject the calender to vibration and periodical nip pressure variation which is reproduced on a paper to be glazed. The elastic asymmetry is also known to be a significant source of known half-critical vibration, which appears when the roll has a rotating frequency which is half of the natural frequency of the transverse vibration of the roll.
An object of the invention is to provide a method capable of extending the service life of rolls and bearings included therein, increasing the running properties and running speed of a paper making machine or a calender, as well as improving the quality of paper by reducing the elastic asymmetry and imbalance of a roll. The measured elastic asymmetry or imbalance is compensated for by making grooves or pockets or by adjusting the size of previously machined grooves or pockets. According to a method of the invention, the grooves or pockets required in a roll due to the functional requirements of the roll are disposed at least in such a manner that, in any case, the grooves or pockets as such do not cause more elastic asymmetry or imbalance in the roll.
BRIEF DESCRIPTION OF THE DRAWINGS
A few exemplary embodiments of the invention will now be described in more detail with reference made to the accompanying drawings, in which
FIG. 1 shows schematically in cross-section a calender fiber roll, including a) a current (prior art) generally used system, b) an improved system of
REFERENCES:
patent: 3755646 (1973-08-01), Muller
patent: 4545021 (1985-10-01), Suzuki et al.
patent: 4826369 (1989-05-01), Bennett
patent: 5331737 (1994-07-01), Jarvela
Patent Abstracts of Japan, vol. 9, No. 272, M-425, abstract of JP, A, 60-116945 (Yasukawa Denki Seisakusho K.K.), Jun. 24 1985 (06.24.85).
Patent Abstracts of Japan, vol. 5, No. 90, M-73, abstract of JP, A, 56-35836 (Hitachi Seisakusho K.K.), Apr. 8, 1981 (04.08.81).
Kuosmanen Petri Olavi
Vaananen Pekka Tapio
Rushing, Jr. Bobby
Valmet Corporation
Young Lee W.
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