KINEMATICS AT THE MAIN MECHANISM OF A RAILBOUND FORGING MANIPULATOR
Florian Ion Tiberiu Petrescu
Bucharest Polytechnic University, Romania
E-mail: petrescuflorian@yahoo.com
Relly Victoria Virgil Petrescu
Bucharest Polytechnic University, Romania
E-mail: petrescuvictoria@yahoo.com
Submission: 26/05/2014
Revision: 14/08/2014
Accept: 26/03/2015
ABSTRACT
Heavy payload forging manipulators are mainly characterized by large
load output and large capacitive load input. The relationship between outputs
and inputs will greatly influence the control and the reliability. Forging
manipulators have become more prevalent in the industry today. They are used to
manipulate objects to be forged. The most common forging manipulators are
moving on a railway to have a greater precision and stability. They have been
called the rail bound forging manipulators. In this paper we analyse general
kinematics of the main mechanism from such manipulator. Kinematic scheme shows
a typical forging manipulator, with the basic motions in operation process:
walking, motion of the tong and buffering. The lifting mechanism consists of
several parts including linkages, hydraulic drives and motion pairs. The
principle of type design from the viewpoints of the relationship between output
characteristics and actuator inputs is discussed. An idea of establishing the
incidence relationship between output characteristics and actuator inputs is
proposed. These novel forging manipulators which satisfy certain functional
requirements provide an effective help for the design of forging manipulators.
Keywords: Mechatronics,
Robotics, Heavy payload
forging manipulators, Rail
bound forging manipulator, Kinematics
1. INTRODUCTION
Heavy payload forging manipulators are mainly
characterized by large load output and large capacitive load input. The
relationship between outputs and inputs, which will greatly influence the
control and the reliability, is the key issue in type design for heavy payload
forging manipulators. Forging manipulators have become more prevalent in the
industry today. They are used to manipulate objects to be forged [1-3].
The most common forging manipulators are moving on a
railway to have a greater precision and stability. They have been called the
railbound forging manipulators. In this paper we analyse the general kinematics
of the main mechanism from such manipulator [1-5].
Kinematic scheme shows a typical forging manipulator,
with the basic motions in operation process: walking, motion of the tong and
buffering. The lifting mechanism consists of several parts including linkages,
hydraulic drives and motion pairs. Hydraulic drives are with the lifting
hydraulic cylinder, the buffer hydraulic cylinder and the leaning hydraulic
cylinder, which are individually denoted by c1, c2 and c3. In lifting process,
the cylinder c1 controls the vertical movement of work piece through inputting
lifting signal. At the same time, the cylinders c2 and c3 are perfectly closed.
While c1 and c3 are closed cylinders, cylinder c2 performs horizontal movement.
While, the cylinders c1and c2 are closed the cylinder c3 realizes leaning
movement by inputting leaning signal in leaning condition.
In direct kinematics one knows l1, l2 and must be
determined: intermediary l3, FI1, FI3, FI6, FI8, FI10 and finally xM, yM. In
inverse kinematics one knows xM, yM (imposed) and must be determined FI1, FI3,
FI6, FI8, FI10, l1, l2, l3 so that the FI angle keeps its constant value
(FI=PI-TETA) to maintain permanently the segment GM horizontally [6-11].
In this work we are solving positions (in inverse
kinematics) with systems V, VI. When we know all these parameters (angles and
lengths) one may determine all kinematics parameters. The concept of modelling
method based on the outputs tasks is defined and investigated. The principle of
type design from the viewpoints of the relationship between output
characteristics and actuator inputs is discussed. An idea of establishing the
incidence relationship between output characteristics and actuator inputs is
proposed. These novel forging manipulators which satisfy certain functional
requirements provide an effective help for the design of forging manipulators
[1-5].
In the next 14 photos one can see
some forging manipulators (independent or on rail) at work [1-5, 11-12].
Figure 1: Forging Manipulator (Rail Mobile)
Source: Dango & Dienenthal
Figure 2: Forging Manipulator (Rail Mobile)
Source: Dango & Dienenthal
Figure 3: Forging Manipulator (Rail Mobile)
Source: Dango & Dienenthal
Figure 4: Forging Manipulator (Rail Mobile)
Source: Dango & Dienenthal
Figure 5: Forging Manipulator (Mobile)
Source: Dango & Dienenthal
Figure 6: Forging Manipulator (Rail Mobile)
Source: Dango & Dienenthal
Figure 7: Forging Manipulator (Independent Mobile)
Source: Dango & Dienenthal
Figure 8: Forging Manipulator (Independent Mobile)
Source: Dango & Dienenthal
Figure 9: Forging Manipulator (Independent Mobile)
Source: Dango & Dienenthal
Figure 10: Forging Manipulator (Independent Mobile)
Source: Dango & Dienenthal
Figure 11: Forging Manipulator (Independent Mobile)
Source: Dango & Dienenthal
Figure 12: Forging Manipulator (Rail Mobile)
Source: Dango & Dienenthal
Figure 13: Forging Manipulator (Rail Mobile)
Source: Dango & Dienenthal
Figure 14: Workstation SSM120 equipment
Source: Dango & Dienenthal
1.1.
Nomenclature
c1 - lifting hydraulic cylinder; c2 -
the buffer hydraulic cylinder;
c3 - leaning hydraulic cylinder; l1,
l2, l3 – variable lengths;
A-L – linkages; A, B, K, F – fixed linkages; j1, j3, j6, j8, j10 -
variable angles; a-g – constant lengths; xB, yB, xA,
yA, xK, yK, xF, yF –
constant coordinates; b, q, j4 – constant angles; j - an angle which must be maintained constant (j=p-q) to keep permanently the segment GM horizontally (as shown in Figure 15).
2. THE STRUCTURE, GEOMETRY AND KINEMATICS OF A RAILBOUND
FORGING MANIPULATOR
In fig. 15 one
can see the kinematics schema of the main mechanism from a railbound forging
manipulator [11].
Figure 15: Cinematic schema of a forging manipulator
main mechanism
Permanently one knows the constant
lengths (a-g) (a to b)and the coordinates (xB, yB, xA,
yA, xK, yK, xF, yF),
(not identify the coordinated) and the j angle who must to be
maintained constant [1-5, 9-12]. (constant angle of 1 to 3 or 1 and 3)
In direct kinematics one knows l1,
l2 and must be determined: intermediary (with systems I, II, III) l3,
j1, j3, j6, j8, j10 and finaly (with system
IV) xM, yM [1-5, 9-12].
In inverse kinematics one knows xM,
yM and must be determined j1, j3, j6, j8, j10, l1, l2,
l3 with systems I, II, III, IV.
It takes four independent vector
contours (KLFK, KIGEDB, AHIK, AHGM) and one can write the below systems (I, II,
III, IV) [1-5, 9-12].
(I)
(II)
(III)
(IV)
2.1.
Inverse kinematics
relationships computing
Then can be determined easily the
parameters j1, j3, j6, j8, j10, l1, l2,
l3 solving the four systems I, II, III, IV. Following relationships (systems
V, VI) are obtained [1-5, 9-12].
(V)
(VI)
2.2.
General kinematics relationships computing
In the fig. 16 one can see the
general kinematics schema of a railbound forging manipulator main mechanism [11].
Figure 16: General cinematic schema of a forging
manipulator main mechanism
At the first step,
starting from the system I derived by time (in function of time), one
calculates the angular velocities in function of the linear velocity of the
engine c1, (see the system 1) [11].
(1)
At the step two,
starting from the system II derivated by time, one calculates the angular
velocities in function of linear velocities of engines c1, c2 (resulting the system 2). Solving every sytem is simple and direct; multiply at
the step a the first equation with a cosine and the second equation with a sine,
one add the two relations rezulted and one obtains an equation linear grade 1
with a single unknown. To the pass b one repeat the procedure but the multiply
of the two equations is different [1-4, 9-11].
(2)
At the step three, starting from the system III derivated
by time, it calculates the angular velocity in function of linear velocities of the engines (actuators) c1, c2 (result the system 3) [6-11].
(3)
At the step four we arrange the system IV and then one
derivated it by time and it obtains directly the scalar velocities of the endeffector
point M (system 4) [11].
(4)
For determining of accelerations must to derivate the
systems I-IV, but we take in consideration a method rapid and directly: we know
now the velocities and one derivate directly their relations; it obtains the
relations from the system 5 [11].
(5)
One determines now and the last kinematics parameters of
the mechanism, for to have a complete cinematic of the main mechanism, which is
necessary and in the kinetostatic and dynamic calculations (systems 6-21) [11].
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
(18)
(19)
(20)
(21)
3. ApplicationS
Presented system can be useful in
all forging oversized, and in particular to
the forging manipulators (independent or on the rail) [1-12]. Railbound forging
manipulators are used when is require an accuracy of positioning very high and
a greater stability.
4. CONCLUSIONS
Heavy payload forging manipulators are mainly
characterized by large load output and large capacitive load input. The
relationship between outputs and inputs, which will greatly influence the
control and the reliability, is the key issue in type design for heavy payload
forging manipulators. Forging manipulators have become more prevalent in the
industry today. They are used to manipulate objects to be forged.
The most common forging manipulators are moving on a
railway to have a greater precision and stability. They have been called the
railbound forging manipulators. In this paper we analyse the general kinematics
of the main mechanism from such manipulator.
Kinematic scheme shows a typical forging manipulator,
with the basic motions in operation process: walking, motion of the tong and
buffering. The lifting mechanism consists of several parts including linkages,
hydraulic drives and motion pairs. Hydraulic drives are with the lifting
hydraulic cylinder, the buffer hydraulic cylinder and the leaning hydraulic
cylinder, which are individually denoted by c1, c2 and c3. In lifting process,
the cylinder c1 controls the vertical movement of work piece through inputting
lifting signal. At the same time, the cylinders c2 and c3 are perfectly closed.
While c1 and c3 are closed cylinders, cylinder c2 performs horizontal movement.
While, the cylinders c1and c2 are closed the cylinder c3 realizes leaning movement
by inputting leaning signal in leaning condition.
In direct kinematics one knows l1, l2 and must be
determined: intermediary l3, FI1, FI3, FI6, FI8, FI10 and finally xM, yM. In
inverse kinematics one knows xM, yM (imposed) and must be determined FI1, FI3,
FI6, FI8, FI10, l1, l2, l3 so that the FI angle keeps its constant value
(FI=PI-TETA) to maintain permanently the segment GM horizontally.
In this work we are solving positions (in inverse
kinematics) with systems V, VI. When we know all these parameters (angles and
lengths) one may determine all kinematics parameters. The concept of modelling
method based on the outputs tasks is defined and investigated. The principle of
type design from the viewpoints of the relationship between output characteristics
and actuator inputs is discussed. An idea of establishing the incidence
relationship between output characteristics and actuator inputs is proposed.
These novel forging manipulators which satisfy certain functional requirements
provide an effective help for the design of forging manipulators.
Presented system can be useful in
all forging oversized, and in particular to
the forging manipulators (independent or on the rail). Railbound forging
manipulators are used when is require an accuracy of positioning very high and
a greater stability.
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