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MINISTRY OF EDUCATION AND TRAINING MINISTRY OF AGRICULTURE AND RURAL DEVELOPMENT
VIETNAM NATIONAL UNIVERSITY OF FORESTRY
NGUYEN THI LUC
DETERMINING OPTIMAL PARAMETERS OF VERTICAL
BAND SAW IN AUTOMATIC WOOD CHAINSAW
Speciality: Mechanical Engineering
Code: 9520103
SUMMARY OF THESIS DOCTOR OF TECHNICAL
HANOI - 2021
Thesis is completed at: VIETNAM NATIONAL UNIVERSITY OF FORESTRY
The Doctoral Advisers: PGS.TS Duong Van Tai
Reviewer 1:
Reviewer 2:
Reviewer 3:
The thesis will be defended at the School-level Thesis Judging Committee at:
Vietnam National University of Forestry
At ……hour............day............month............year 2021
The thesis can be found at the library: National Library of Vietnam
Vietnam National University of Forestry Library
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PREAMBLE
1. Urgency of the research problem
In 2016, the Ministry of Science and Technology assigned the Forestry
University to lead a state-level project on "Research, design and manufacture
automatic wood sawing equipment lines with a productivity of 3 -4 m3/h of wood has
finished products” code ĐTĐL.CN-10/16. The project has designed and manufactured
an automatic wood sawing line, but the project has only stopped at the design,
manufacturing and testing part of an automatic wood sawing line model. Has not reseach
the dynamics of vertical band saw in cutting process and optimize the parameters of the
equipment in the system.
In the automatic wood sawing line, the vertical circular saw is an important
device that greatly affects the ability and working efficiency of the line. It is very
necessary to research and optimize the technical parameters of vertical circular saws in
order to improve productivity and product quality.
Stemming from the above issues, I choose and carry out the thesis topic: "
Determining optimal parameters of vertical band saw in automatic wood chainsaw ".
2. Research objective
Building models, setting up dynamic equations, vibration equations of vertical
band saw blades, surveying dynamic equations, determining some optimal parameters of
vertical band saws in automatic sawing lines, to improve productivity and product
quality.
3. New contributions of the thesis
- Built a dynamic model of vertical band saw, established and investigated the
system of differential equations of motion and the vibration equation of the saw blade.
The survey results have determined the values of some geometrical, kinetic and dynamic
parameters as the basis for the design and manufacture of vertical band saws.
- Has been built a theoretical basis for setting up and solving multi-objective
optimization problems with many influencing parameters, which can be used for similar
problems. For vertical circular saws, has been 6 control parameters of the optimization
problem have been selected with 2 objectives, in which using the similarity and
dimensional methods to build the correlation function. According to this method, the
number of basic experiments has been reduced by more than 4 times, thus reducing the
experimental, while still ensuring all 6 parameters change at the necessary levels.
- Has been built a dynamic experimental research model, some dynamic
parameters of vertical band saws have been determined to serve the survey problem and
verify the established theoretical computational model.
- By empirical research, the thesis has determined the values of the parameters
when sawing for Ash wood (Fraxinus) are: initial tension S0= 1876(N); cutting speed v =
55 m/s; pushing speed uc = 0,123 m/s; saw blade cutting angle δ = 580, wood diameter d
2
= 62 cm. With these above parameters, the specific energy cost Ar min = 1,72 kWh/m2 and
the surface roughness of sawn board Ramin =0,173 mm, then the average sawn yield was
calculated Πv= 3,12 (m3/h) ˃ [Πv] = 3(m3/h).
4. Scientific significance of the research results of the thesis topic
- From the system of kinematic equations set up, survey the graph of velocity
and acceleration, determine the nonuniform coefficient (ψ) of angular velocity, the
dynamic coefficient (kđ). Investigate the influence of the flywheel moment of inertia (Ibđ)
on the non-uniformity coefficient, the dynamic coefficient. Investigate the effect of saw
blade tension (S0) on specific energy cost and sawn circuit quality. The survey results
have built the correlation chart between Ibđ and ψ, and the table S0 with the shear force
resistance of each type of wood (kc). That is the scientific basis for determining
reasonable values of some parameters of vertical band saws.
- From the vibration equation of the saw blade, survey the graph, determine the
horizontal vibration amplitude of the blade as a basis for assessing the quality of the
sawn board surface.
- Applying the theory of similarity and dimensions in experimental research has
built a general method to set up and solve the problem of optimizing the parameters of
vertical band saws. This method can be used for problems with many similar influencing
parameters in engineering.
5. The practical significance of the thesis topic
- The research results of the thesis are used for the design, manufacture and
completion of vertical band saw in automatic wood sawing lines by the state-level
project code ĐTĐL.CN-10/16design and manufacture.
- The results of the thesis can be used as a reference for research units and vertical
band saw manufacturers.
Chapter 1
OVERVIEW OF RESEARCH ISSUES
1.1. Overview of research works on optimization of vertical band saws in Vietnam
and around the world
The research on vertical band saw in Vietnam is still very little, especially on
optimization issues, there are almost no works that fully consider the objectives with
many influencing parameters, for the sawing object wood from Vietnam.
In the world, there are many types of vertical band saws in automatic wood
sawing lines that have been applied in practice, but the announcements about the optimal
calculation results of vertical band saws are still limited.
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1.2. The subject of the thesis research
1.2.1. Research equipment
Vertical band saw in automatic wood sawing line designed and manufactured by
the state-level project code ĐTĐL.CN-10/16. The structure diagram of the vertical band
saw is shown in Figure 1.1.
1- Saw blade;
2- Active flywheel;
3- Passive flywheel;
4- Hydraulic saw blade tensioning
mechanism;
5- Saw blade stabilizing mechanism;
6- Saw blade stabilizing mechanism;
7- Saw blade stabilizing mechanism;
8- Flywheel cleaning mechanism;
9- A woode rickshaw;
10 - Electric motor;
11- Bracket system;
12 - Passive pulley;
13 - Active pulley.
Figure 1.1: Structure diagram of vertical
band saw
1.2.2. Materials put into sawing
According to the material design of the automatic sawing line, designed and
manufactured by the state-level project, are imported or domestic plantation timbers with
diameter from 30cm to 80cm, log length ≤ 4m, wood group from group 2 to group 6.
Based on the test results usage needs, the most suitable type of wood for the
automatic sawing line is Ash wood (Fraxinus) imported from Europe with a diameter of
30÷80cm, this is a type of wood with high density medium hardness.
1.3. Research content
In order to achieve the objectives set out, the thesis proposes the following
research contents:
1.3.1. Determination of basic parameters of vertical band saw according to working
conditions
- Build and investigate the dynamic model of vertical band saw. Based on safety
and stability conditions to determine some structural and technical parameters;
- Build and survey the horizontal vibration model of the saw blade to find out
the causes affecting the surface quality of sawn boards. From there, a solution to reduce
the horizontal vibration of the saw blade is proposed.
1.3.2. Determine the optimal value of some parameters according to the criteria to
evaluate the efficiency and quality of the sawing process