Surashov Nurgali
Tolymbekovich, Academician of NANS of Republic Kazakhstan, Doctor of technical sciences,
Professor;
Ahmetova Sholpan Dauletovna, Candidate of technical sciences, Associate
Professor
Kazakh National Technical
University after K.I.Satpaev (KazNTU)
Republic Kazakhstan
Determination
of optimal parameters formulated by dump of bulldozer taking
into account the prism of drawing
Special place at improvement of technology and mechanization of
construction production is occupied earthmoving machines for interlaminar
development of soil. In spite of the fast growth of new methods of development
of soil, a mechanical way of digging and moving by working body (WB) of
landslip type remains the most effective method of carrying out of earthwork in
the near future.
The branch of digging equipment in
the countries of CIS is developed in Russia and Ukraine, and Kazakhstan is the
consumer of these cars. There are Kentau Excavator plant, Pavlodarsky Tractor
plant, Kalkamansky plant of working organs and some other repair plants in the
Republic of Kazakhstan which produce repair equipment for building and road
cars.
That is why at the initial
phase of innovational and industrial
politics of the country should be directed to produce the whole army of working
multipurpose equipment which you can buy at leading firms because at present
there is no any opportunity to produce them in Kazakhstan. Existing repair
plants of the former «Sredmash» can produce repair equipment cars.
One of the important site of earthmoving machines are working bodies which have great technical
opportunities, which gives you to use energetic, labor
and material recourses.
The general requirement to dumps of earthmoving machines is providing the set productivity at
physical and mechanical properties of moved soil from which depend the form and
dump parameters.
The main parameters (picture 1) are: B
and Í – respectively are width and
height of a dump, m; Hk – height of a peak, m; R
– radius of curvature of a dump, m; l –
length of an arch of a dump, m; φ –
the central corner of a dump’s curvature, grade, â' – distance from the dump bottom p to a contact point on
height with soil, m; P – perimeter
of interaction contour of moved soil with a dump, m; C –
height of a prism part of the drawing, towering over a peak, m; a' –
width of the side roller ,m.
Picture 1 –
The scheme of dump interaction with soil at the maximum prism of drawing
a - the scheme of front
surface interaction of a dump with a drawing prism;
á-
longitudinal section of a dump and a drawing prism
The main operational parameters are: V gr – speed of moving with soil of bulldozer’s dump, km/h; p – a corner of an internal friction of soil in rest, grade; ε
– angle of the dump’s blade, grade; P – operational performance
of the bulldozer, m3/h.
To increase the efficiency of
bulldozer dumps use and also its
technical and operational
productivity, reduction of metal consumption and bulldozer’s power
consumption at the beginning it is necessary to review various constructive
forms accounting of a drawing prism set
and then to determine their optimum design data on the basis of a dump’s
rational form.
It is known that the bulldozers dumps
which are now in exploitation
in its constructive form don't answer to modern requirements from the point of
view of efficiency of their use on the interaction area with moved soil that,
in turn, conducts to a metal consumption increase and of course bulldozers
power consumption.
The analysis of interaction process
of the bulldozer working body with various category of soil allowed to develop
essentially new designs of dumps with top side bevel and knifes expanders that, caused preservation
of the maximum prism of drawing at its transportation (picture 2).
Picture 2 –-
Rational form of bulldozers dumps
Constructive key
parameters of new designs of dumps should be determine with account of a corner
of a natural slope p and perimeter P on which moved soil concerns with a dump.
The area of transverse section
of soil cooperating with a dump (see ðicture 1) determined from the
sum
(1)
where 
– the area of a rectangle of abcd; 
– the trapeze area (àâæå); 
– the trapeze area (àáæñ); 
– the segment area (êëì); 
– the area of triangles (side rollers): (adí) and (âñç).
It is possible to determine the area of a rectangle abcd by the following
formula
(2)
It is necessary to determine the trapeze area (àâæå) by the following expression
(3)
The area of a trapeze it is defined from the following expression
(4)
The segment area (êëì) is equal
(5)
The area of triangles (àdí) and (âñç) is possible
to determine by the following dependence
(
)
(6)
Summarizing all areas, formulas
(2)... (6), we will define the area of frontal section of moved soil
cooperating with a dump.
(7)
This
expression represents function of the area of frontal section of the moved soil
cooperating with a surface of a dump, depending on design data of a bulldozer’s
dump (B,H, Hê, â', a').
Consider in each
case constant height of a
dump and a corner of a natural slope, we will find optimum values of constructive parameters: distances
from the ground dump to a
contact point on height with soil, â'.
For this purpose we’ll differentiate the right part of
expression (7) on â'
(8)
Equating a derivative to zero and
having made the appropriate conversion, we will receive the following equation
(9)
which
expresses optimum values â' for concrete values B,H
and Hk and solving it relatively â' we will receive
(10)
Constructive optimal parameters of new constructive
dumps determined by research of the areas of transverse section of the soil interacting with working
bodies it is possible to present as
follows:
1.
Height of a dump, H
(11)
2.
Height of a peak, Hk
(12)
3.
Width of a dump, B
(13)
4.
Distance from the dump basis to a contact point
on height with soil, â'
(14)
5.
Width of a peak of a dump, Bk
(15)
6.
Perimeter of a dump, Ð
(16)
7.
Additional width of a knife expander, a
(17)
where a' = â' · tgp – width of the side roller
of soil, m; káâ – ratio of
width of a knife expander; we accept structurally: káâ = 0,4 – for
cohesive soils; káâ = 0,6 – for disconnected soil.
Then the height of an additional
knife expander is equal:
(18)
where 
– ratio of height of a knife expander (we accept structurally);
= 1,2 – for
cohesive soil; 
= 1,3 – for disconnected soil.