Presenting a Railbound Forging Manipulator

8/10/2019 Presenting a Railbound Forging Manipulator

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Presenting a Railbound Forging Manipulator

PETRESCU Florian Ion1, a *,PETRESCU Relly Victoria

2,b

1Polytechnic University of Bucharest, Theory of Mechanisms and Robots department, Bucharest,

RO

2Polytechnic University of Bucharest, Transport, Traffic and Logistics department, Bucharest, RO

[email protected],

[email protected]

* The corresponding author

Keywords:Railbound forging manipulator, heavy load, control, reliability, manipulate objects to beforged, moving on a railway, precision, stability, geometry, structure, cinematic, forces.

Abstract.Heavy payload forging manipulators are mainly characterized by large load output and

large capacitive load input. The relationships between outputs and inputs have greatly influence

about the control and the reliability. Forging manipulators have become more prevalent in theindustry 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 one presents the general aspects of a

railbound forging manipulator, like geometry, structure, general kinematics and forces 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. An idea

of establishing the incidence relationship between output characteristics and actuator inputs is

proposed.

Introduction

A railbound forging manipulator is presented in the fig. 1.

Fig. 1.Photo of a railbound forging manipulator


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The kinematic chain plan (the kinematic diagram) of the main mechanism, which fall within a

single plane or in one or more of the other plane parallel to each other, is presented in the fig. 2 [1-

5].

Fig. 2.Cinematic schema of a forging manipulator main mechanism

Nomenclature

c1 - lifting hydraulic cylinder; c2 -the buffer hydraulic cylinder;

c3 -leaning hydraulic cylinder; l1, l2, l3variable lengths;

A-L linkages; A, B, K, F fixed linkages; 1, 3, 6, 8, 10 - variable angles; a-g constant

lengths; xB, yB, xA, yA, xK, yK, xF, yF

constant coordinates; , , 4

constant angles; - an anglewhich must be maintained constant (=-) to keep permanently the segment GM horizontally.

Fm1, Fm2, Fm3the driving forces of the mechanism.

Mechanism structure

Then can be determined easily and the structural schema (see the fig. 3).

Fig. 3.Structural schema of a forging manipulator main mechanism


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Applied Mechanics and Materials Vol.

The structural formula can be determined from the structural diagram (relationship 1).

)11,10,6(1)9,8,5(1)4,3(0)7,2,1(1)0( DMDMDMDMEF (1)

It is obtained: three motor dyads, one classic dyad, and a fundamental item 0 [1-5].

The mobility of the mechanism is determined with the formula (2).

33033015211323 453 CCmM (2)

It follows three degrees of freedom corresponding to the three actuators (motors) linear.

The wiring diagram can be determined now using the structural formula (see the fig. 4).

Fig. 4.Wiring diagram of a forging manipulator main mechanism

Mechanism kinematics

Permanently one knows the constant lengths (a-g) and the coordinates (xB, yB, xA, yA, xK, yK, xF,

yF), and the angle who must to be maintained constant [1-5].

In direct kinematics one knows l1, l2and must be determined: intermediary (with systems I, II,

III) l3, 1, 3, 6, 8, 10and finaly (with system IV) xM, yM[1-5].

In inverse kinematics one knows xM, yMand must be determined 1, 3, 6, 8, 10, l1, l2, l3with

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].

813

813

sin)sin()(

cos)cos()(

lgyy

lgxx

FK

FK (I)

36102

36102

sinsinsin)(

coscoscos)(

ealyy

ealxx

KA

KA (III)

613

613

sin2sinsin

cos2coscos

alby

albx

K

K (II)

6103

6103

sin)sin(sin)(

cos)cos(cos)(

aflyy

aflxx

MA

MA (IV)

Inverse kinematics relationships computing

Then can be determined easily the parameters 1, 3, 6, 8, 10, l1, l2, l3solving the four systemsI, II, III, IV. Following relationships are obtained (systems 3 and 4) [1-5].


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)arccos(cos)(sin)sin(sin

sin

)cos(coscos

)arccos(cos)(sinsinsin2

sin

coscos2cos

];sin)sin(cos)cos[(4)sin()cos(4

);arccos(coscos

101010

3

610

3

610

111

3

61

3

61

03

66

222

0

22

442662

3

2

2

2

1

2

3

2

2321

6

sign

l

yyfa

l

xxfa

sign

l

bya

l

bxa

Al

bybxabybxaA

eAAlAA

AAAAAA

AM

AM

K

K

KKKK

(3)

)sin(sin)cos(cos

)]sin([2)sin(4

)]cos([2)cos(4)]sin([)]cos([)sin()cos(3

)arccos(cos)(sin)sin(

sin

)cos(cos

)]sin([)]cos([

)arccos(cos)(sinsinsin

sin

coscoscos

6106104

3

2

22222

1

888

1

38

1

38

2

3

2

31

333

61023

61023

KAKA

AMK

AMK

AMAMKK

FK

FK

FKFK

KA

KA

yyaxxaA

fyyabyaA

fxxabxaAfyyfxxbybxaA

sign

l

gyy

l

gxx

gyygxxl

sign

e

alyye

alxx

(4)

Determining driving forces of the main mechanism

RELATIONSHIPS COMPUTING

In step 1 (starting from system 5) it calculated the all external forces from the mechanism (The

inertia forces, gravitational forces and the force of the weight of the cast part).

1010

11,1011,10

11,10

88

8989

89

7

77

7

35

55

5

44

44

4

66

66

66

33

33

3

11

1212

12

11,10

1010

1010

8

88

88

7

77

77

5

55

55

4

44

44

6

66

3

33

33

1

11

11

0

G

i

G

iy

G

G

ix

G

G

i

G

iy

G

G

ix

G

M

i

M

M

iy

M

M

ix

G

i

G

iy

G

G

ix

G

G

i

G

iy

G

G

ix

G

G

i

G

iy

G

G

ix

G

H

i

H

iy

G

HGixG

G

i

G

iy

G

GixG

G

i

G

iy

G

GixG

JM

gmymF

xmF

JM

gmymF

xmF

JM

gMyMF

xMF

JM

gmymF

xmF

JM

gmymF

xmF

JM

gmymF

xmF

JM

gmymF

xmxmF

JM

gmymF

xmF

JM

gmymF

xmF

M

(5)

Is then calculated all the forces from couplers. In the end we can determine and (three) driving

forces [1-5]. In figure 5 can be monitored engine element c1 composed of kinematic elements 8-9.


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Applied Mechanics and Materials Vol.

Determine motive power Fm1with relations of the system 6; being two relations of calculation may

be carried out a check.

8

8

)8(

8

8

)8(

sin0sin0

cos0cos0

8

181

8

181

y

L

iy

G

m

y

L

iy

Gmy

x

L

ix

G

m

x

L

ix

Gmx

RF

FRFFF

RFFRFFF

(6)

Fig. 5.Kinematics schema of the motor mechanism c1

In figure 6 can be monitored engine element c2 composed of kinematic elements 10-11, and

determine motive power Fm2with relations of the system 7 [1-5].


10

10

)10(

10

10

)10(

sin0sin0

cos

0cos0

10

2102

10

2102

y

H

iy

G

m

y

H

iy

Gmy

x

H

ix

G

m

x

H

ix

Gmx

RFFRFFF

RFFRFFF

(7)


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In figure 7 can be monitored engine element c3 composed of kinematic elements 1-2, and

determine motive power Fm3with relations of the system 8 [1-5].


1

1

)1(

1

1

)1(

sin0sin0

cos

0cos0

1

313

1

313

y

E

iy

G

m

y

E

iy

Gmy

x

E

ix

G

m

x

E

ix

Gmx

RFFRFFF

RFFRFFF

(8)

Conclusions

Forging manipulators themselves have become more prevalent in the industry today.

An idea of establishing the incidence relationship between output characteristics and actuator

inputs is proposed (see the relations from systems 3 and 4).The main problems are solving positions, speeds and motor forces of the main mechanism. In

the end we can determine and (three) driving forces (the relations from systems 6-8).

References

[1]F. Gao, W. Z. Guo, Q. Y. Song, F. S. Du, Current Development of Heavy-duty Manufacturing

Equipment, Journal of Mechanical Engineering, Vol. 46, No. 19, 2010, p. 92-107.

[2]H. Ge, F. Gao, Type Design for Heavy-payload Forging Manipulators, Chinese Journal of

Mechanical Engineering, Vol. 25, No. 2, 2012, p. 197-205.

[3]G. Li, D.S. Liu, Dynamic Behavior of the Forging Manipulator under Large Amplitude

Compliance Motion, Journal of Mechanical Engineering, Vol. 46, No. 11, 2010, p. 21-28.

[4]C. Yan, F. Gao, W. Guo, Coordinated kinematic modeling for motion planning of heavy-duty

manipulators in an integrated open-die forging center, Journal of Engineering Manufacture,

Vol. 223, No. 10, 2009, p. 1299-1313.

[5]K. Zhao, H. Wang, G. L. Chen, Z. Q. Lin, Y. B. He, Compliance Process Analysis for Forging

Manipulator, Journal of Mechanical Engineering, Vol. 46, No. 4, 2010, p. 27-34.

Presenting a Railbound Forging Manipulator

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