ISSN: 1693-6930
TELKOMNIKA Vol. 14, No. 3A, September 2016 : 194 – 201
195 movement drives. In addition, 4 degrees of freedom owned to the simulation model where A, B,
C, D, E, F, G, H, I, J, K and M were hinge points for each rigid bodies.
Table 1. Hydraulic cylinder parameters of working device mm
Device Minimum length
Maximum length Cylinder stroke
movable arm cylinder
1760 3000
1240 Bucket rod
cylinder 1450
3400 1470
Bucket Cylinder 1635
2700 1065
1-bucket; 2-bucket rod; 3-movable arm; 4-rotary platform; 5-arm hydraulic cylinder; 6- piston rod of movable arm hydraulic cylinder; 7-linkage; 8-bucket linkage; 9- hydraulic cylinder piston rod of bucket; 10-bucket hydraulic cylinder;
11-bucket rod hydraulic cylinder; 12- piston rod of bucket rod hydraulic cylinder.
Figure 1. Simulation Model of working device
3. Theoretical Load Calculation Hydraulic Excavator
When in use
，
the loads types and its distribution is very complex for hydraulic excavator. Digging load was mainly composed of mining resistance, material weight and
working devices own weight. Due to the influence of excavation resistance on the reliability and excavating ability of the working device is significant, so the digging resistance force must be
analyzed and calculated. The digging resistance force is usually generated by the combination of the frictional force from bucket cutting soil as well as the cutting and pushing resistance
forces from soil [5]. According to the tangential and normal direction from digging trajectory, digging resistance force could be decomposed into tangential and normal direction.
Furthermore, it could be approximated to that apply on the bucket tooth tip, the experience formula as [6]:
Tangential digging resistance force:
max max
t t
W K bh
1 Normal digging resistance force:
max max
n t
W W
2 where:
is the coefficient of digging specific resistance force Nmm
2
, which refers to the resistance force that soil to overcome when dug a unit area of soil. It is a comprehensive
reflection of the bucket digging resistance combined. is the bucket width or digging width mm.
max t
h
is the digging depth, generally take 0.1~0.33 b mm. is the coefficient of digging resistance force.
K
b
TELKOMNIKA ISSN: 1693-6930
Dynamic Simulation Analysis of Working Device for Hydraulic Excavator … Guiju Zhang 196
According to literature [7, 8], the soil type was selected as grade Ⅲ and
2
cm N
19.5 K
, b=120cm,
. ,
=0.42. The results after calculating are: the tangential and normal digging resistance forces
respectively are equal to 56.16KN and 23.59 KN. In practical operation, the digging resistance force not only related to bucket’s shape, friction resistance force between bucket and soil and
soil’s cutting resistance force, but also related with the position of hydraulic excavator, the system’s working pressure and the working area of digging hydraulic cylinder piston. So the
digging resistance force by 1.5 times was used to check in calculation of the excavating resistance. i.e.
max t
W
=1.5×56.16KN=84.24 KN
3
n max
W
=1.5×23.59 KN=35.385
KN 4
The formula for calculating the gravity of the excavated material is:
5 Where,
is the density of soil with value . x
‐6
kgm ; is the volume of bucket with value 1.05m
3
; g is the acceleration of gravity with value . x
mms . Finally the result of G is equal to 18.5 KN after calculating.
4. Control for Function
