Energy-saving press roll
HIDEMASA IIJIMA* 1
TOSHIYUKI NOBUMOTO* 1
SETSUO SUZUKI* 1KOSHI TANIMOTO* 2
MOTOYUKI FUJII* 2
HIDEO NOGAMI* 2

With environmental problems including CO2 emission becoming more serious day by day, all autonomous bodies
and industrial organizations are implementing countermeasures. Mitsubishi Heavy Industries Ltd. (MHI) has recently developed a new press roll, reported in this paper, which is effective for power saving. This press roll isdesigned to greatly reduce power loss from oil agitation by efficiently collecting and scavenging the lubrication oil
inside the roll. This system roll has also been shown to be effective in reducing the temperature of the scavenged oil.
So far, seven units of rolls of this type have been delivered to users.

1. Introduction
Global environment problems such as global warming due to CO 2 emission are becoming more serious day
by day, and all autonomous bodies and industrial organizations are seriously engaged in countermeasures.
Factors such as soaring oil prices have also been worsening the situation recently, and the paper industry has
been taking various countermeasures including powersaving.
Meanwhile, in many recent cases, the need for faster
operation of paper making machines is being traded forpower saving: the faster the machine operation, thegreater the power saving effect. MHI has long been promoting such countermeasures and has developed a pressroll that saves power effectively in the area of press parts
which reportedly occupy a high percentage of power consumption in the paper making process. This paper
reports on the details of this development work.

MH Shoe Press
C RollMulti-hybrid shoes

2. Structure of the MHI paper machine pressCenter shaft

Fig. 1 shows the structure of the MHI paper machinepress roll. In this paper, the case of MH Shoe Press CRoll is shown as a representative example. In order tosupport the large load from the shoe module, whichamounts to approximately 1 000 kN/m, many shoes arearranged on the center shaft of the Press C Roll and support the inner surface of the roll shell through oil film.
Fig. 2 shows the power saving concept. In the Press
C Roll, an ideal lubrication oil film is formed between
the multi-hybrid shoes and the shell's inner surface toresist the load from the shoe module(1). For this purpose,
it is necessary to supply enough oil to the leading edgeof the shoes.
At this time, when there is no scavenging oil pan,the excess oil at the shoes' leading edge is scraped off.
*1 Paper & Printing Machinery Division*2 Hiroshima Research & Development Center, Technical Headquarters

Fig. 1 Structure of MHI paper machine press
Shoe module and Press C Roll configurations are shown.

Accordingly, when the oil circulates inside the roll, ittends to power loss from oil agitation when coming into
contact with various points. This is a particularly serious problem in the case of the latest high-speed papermachines.
However, with the newly developed scavenging oil pansystem, enough oil is supplied to the leading edge of theshoes and only the excess oil is immediately recovered,drastically reducing the power loss from oil agitation.
This reduction of power loss from oil agitation is the main
point of the power saving.
Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 43 No. 3 (Sep. 2006)

1Multi hybrid shoe

Scavenging oil pan

Excess oil(a) In case of no scavenging oil pan(b) In case of scavenging oil pan in place

Fig. 2 Power saving concept
Conceptual drawing of reduction of agitating power by adoption of scavenging oil pan. Excess contactof oil against shoes will be eliminated immediately.
1.05

Power ratio (P/P0)

Meanwhile, the circulating lubrication oil also takeson the role of cooling the roll itself and the reduced power
consumption also contributes greatly to reducing the temperature of the lubrication oil. In other words, thescavenging oil temperature is lower on exit from the roll.
These effects allow us to anticipate a thicker lubrication
oil film, better protection of the roll cover, prevention oflubrication oil deterioration and other benefits.

3. Machine operating results

1.00

0.95

7 - 9%
reduction

0.90

0.85
Speed (V)(a) Record of power saving performance

MHI has already delivered seven units of the scavenging oil pan system rolls including other types to bedescribed below, and the effectiveness of each unit has
been proven. This paper reports on the performancerecord of one that was delivered to a user company.
Fig. 3 shows the performance record of power savingand scavenging oil temperature reduction of the machineat the said user company. This record is just one exampleof the reduction effects, which may differ depending on
individual operating conditions and machine configuration. It should also be noted that (a) in said Fig. 3 shows
power saving at a certain speed as normalized with power
before application of the scavenging oil pan.
It can be understood from this data that the reduced
power consumption effect involving the power of the press
as a whole is 7 to 9% and the scavenging oil temperature
reduction effect is 5 to 6 oC. Regarding the reduced power
consumption, approximately 8 million yen may be saved
when the effect is converted to the machine of MHI's standard press type, size and speed. In addition, if thescavenging oil temperature can be lowered by about 5oC,
this will be very effective in eliminating the problem
encountered when the machine speed is increased.

Scavenging oiltemperature

Data before applicationof scavenging oil pan

Data after applicationof scavenging oil pano5-6 Creduction(b) Performance record of scavenging oil temperature reduction
Fig. 3 Record of effects of scavenging oil pan application
Record of power reduction and scavenging oil temperature reduction(example at a user company). Power is normalized with power of thepress as a whole at a certain speed before application of scavenging
oil pan.

the roll. Fig. 4 shows the appearance of the model testroll and the behavior of the working fluid.
By means of this test roll operation, it was found thatwhen there is no scavenging oil pan, the excess working
fluid that comes in contact with the shoes changes its
direction, falls, and is then brought up again to the rotating inner shell surface where it is again pushed
against the shoes, repeating the cascading phenomenon.
When the scavenging oil pan is installed, however,most of the scavenging oil is recovered immediately by
the pan and no disturbance of the fluid on the shoes'
leading edge is observed. This fact thus seems to contribute greatly to reducing the agitating power.

4. Optimization of oil scavenging system
Before determining the scavenging oil pan structure,
MHI manufactured a small-scale model test roll to visually ascertain the behavior of the working fluid inside

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 43 No. 3 (Sep. 2006)

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Center shaft assimulated

Transparent shell

Before application ofscavenging oil pan

After application ofscavenging oil pan

Power (P): Others: Agitation: Shoe friction

Power loss
from oil agitation(a) Appearance of model test machine

Fig. 5 Component power and estimation of scavenged oil paneffects
Application of the scavenging oil pan greatly reduced the power loss
from oil agitation. The item "Others" includes pump power, etc.

Excess oil contacts

Estimation of these power losses and reduction effects
has been made by applying MHI's theoretical estimation method. A power loss and scavenging oil temperature
estimation system was created with heat balance taken
into consideration, and analyses were then made.
Fig. 5 shows the analytical results of the Shoe Press
C Roll power. The item "Others" in this figure includes
pump power, etc. This figure confirms that before application of the scavenging oil pan, the power loss from oilagitation occupied as large a portion as the shoe viscous
frictional power loss.
By contrast, it can be understood from Fig. 5 that after application of the scavenging oil pan, a large part ofthe power loss from oil agitation could be removed, contributing to power saving.
These simulation results have also shown that theanticipated reductions had for the most part been attained.

(b) Behavior of working fluid (without scavenging oil pan)

[Scavenging oil pan system]
Excess working fluid contacts with shoes
are immediately eliminated by the pan.

6. Application to other types
The preceding section dealt with Press C Roll of theso-called center roll type. In other cases, the scavenging oil pan was applied to the self loading type; thedynamic shoe type was treated for power saving; andvarious other measures were taken. In this section, anexample of application to the self loading type will beintroduced.
Fig. 6 shows a conceptual drawing of scavenging oil
pan installation in the case of the self loading type. In
the case of the self loading type, the space inside the rollis limited and the shoe stroke is long, so the center roll
type scavenger oil pan cannot be applied as is. Throughthe visualized test with the model machine describedabove, MHI has established a scavenging oil pan structure and layout that can be sufficiently effective evenunder such limited conditions. Some such products havealready been delivered to user companies.

(c) Behavior of working fluid (with scavenging oil pan in place)Fig. 4 Small-scale model test machine
The behavior of the working oil inside could be visually observed by
fast rotation of the test roll made of transparent shell.

5. Analysis of the effects
The various effects described in the preceding section
can generally be explained by numerical calculations. The
following section will present an estimation and theanalysis results of these effects.
The power loss generated inside the Press C Roll consists mainly of the following:(1) Shoe viscous frictional power loss
(2) Power loss from oil agitation inside the roll(3) Others

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 43 No. 3 (Sep. 2006)

3Power consumption reduction ofpress per unit width (kW/m)

Excess oil(a) In case scavenging oil pan is not installed

14121086420
1 200

1400

1 600

1 800

Reel speed (m/min)

Scavenging
oil panFig. 7 Estimation of effects on self loading type
Power reduction effect at various speeds as recorded
on a commercially operating press at a user company
is shown using curve fitting techniques.

as the machine speed increases. This effect has been estimated and analyzed by numerical simulation andtesting and also proven to be effective in reducing thescavenging oil temperature.
Seven rolls of this type of roller have so far been delivered to users including the one introduced herein, andthe effectiveness of this type of roller has been recognized by these users.
This innovation is applicable, though under some restricted conditions, to the shoe calender as well as to thepress part center roll type and self loading type dealt
with in this report. Many variations exist. MHI will continue to study power saving techniques to meet the needsof the customers.
As mentioned in this paper, the scavenging oil panstructure, the effect of power reduction, the scavenging
oil temperature reduction, etc. may differ depending on
the individual machine structure, speed, operating condition, etc. Please contact the business department ofMHI to ensure that your needs are met satisfactorily.

(b) In case scavenging oil pan is installed
Fig. 6 Application to self loading typeThin-type scavenging oil pan is applied to the self
loading type which has smaller space.

Fig. 7 shows the results thereof in which the power
reduction effect was estimated from the power record ofa user company using the estimation system describedin Section 5 above and shown as normalized with reference to wire width. This result has demonstrated thesame power saving effect on the self loading type as on
the center type.

7. Conclusion
A new type of press roll that is effective for powersaving has been developed. This development was accomplished by restricting the movement of oil inside theroll and effectively scavenging it for the main purpose ofreducing the power loss from agitation of the lubrication oil inside the roll, which becomes more significant

Hidemasa Iijima

Toshiyuki Nobumoto

Reference(1) Suzuki, S. et al., Multishoe Caliper Controlled Roll with Static
Bearing Technology, Mitsubishi Heavy Industries TechnicalReview Vol. 39 No.1 (2002)

Setsuo Suzuki

Koshi Tanimoto

Motoyuki Fujii

Hideo Nogami

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 43 No. 3 (Sep. 2006)

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