Prefabricated Carbide Tips Handling

Prefabricated Carbide Tips Handling D. Milutinovic, M. Pilipovic, Mechanical Engineering Faculty, University of Beograd/Yugoslavia Submitted by M.Kalajdiic (1) Received on January 16,1991

The solving of the problem of automated handling of pre-fabricated carbide tips aimed at improving and maintaining the quality, productivity and humanization of work is a very complex engineering task. The complexity of the problem of automated handling primarily relates to the possibility of easy damageability of pre-fabricated tips very limited space and short time cycle for their taking out of the press. The paper in detail analyses this problem and presents a developed concept of a manipulation modular-based'system. In comparison with the existing systems the basicadvantage was achieved i.e. the flexibility and sophisticated control. This developed system solves the problem of the handling of pre-fabricated tips in small companies. Summry:

Keywords: Handling, carbide inserts, manipulation system.

1. INTRODUCTION

The automated manipulation of carbide inserts during all production phases is essential for increasing of the productivity, raising and maintaining of the constant level of the quality of the product and the humanization of work.

ing batches and limited number of presses. Under such conditions in addition to the above requirements the problem of automatized manipulation gets even more complicated because of the added high flexibility requirement.

The manipulation of compacts during their green state is a complex task including their picking and taking out of tools, transporting to the pallets (sinterring trays) and their stacking and optimum packing. Here several strict restrictions should be borne in mind such as easy damageability of compacts, limited number of small surfaces for their taking and placing, restricted available space and short cycle time for picking and taking of compact from the tools, as well as high accuracy required for the positioning and orientation during their placing and packing.

In the workshope for which the attempt was made to solve the problem of automatic compact manipulation a detailed analysis of the technological task for the manipulation system in question was first made which included: - the classification of the production program according to the shape, dimension and mass.The representative examples are shown in the central part of Figure 1, - the definition of the type of the gripper, modeof picking subject to the shape of compacts, their position in the tools and subject to possible picking surfaces- left part of Figure 1, - the definition of the placing mode in relation to the picking mode, and possible placing surfaces, - the optimum packing distribution in view ofcompact shapes and possible placing surfaces-the right part of Figure 1 , - the analysis the cycle time of the press and the time available for picking and taking out of compacts from the tools, and their placing an sinterring trays and further packing, and - the analysis of all other requirements and restrictions related to the process, press, tools, and the like.

The solving of the problem of automatic manipulation of compacts was paralelly undertaken by the producers of power presses for this purpose, as well as by the producers of inserts. This has led to the development of several systems with very different concepts. The start was made with the system where compactsweretaken from a small conveyor where they were placed by some simple mechanism activated by the press. This concept was abandoned because of great damageability of compacts, and the lack of universality as a large number of campact types could not be so easily placed on the conveyer because of their specific shape and the position in tools. There are today only several manipulation systems in which the compacts are directly taken out of the tools. All these solutions consisted from a manipulator and the table with the sinterring tray on which compacts were packed. If the manipulator had a more complex kinematics the table had a simpler one, and vice versa. Although one deals here with principally universal systems, because of physical intervention during the change of compacts their use is suitable for mass production only. Their price is, however, very high. All the above and the need for a flexible solution of the manipulation and packing problem in small companies with a wide assortment of compacts produced in small batches have led to the undertaking of the research [l] the results of which are partly described in this paper. The starting point was the principles and the methods of analysis of work places for the purpose of robotization, as well as the principles and methods of technological task based robot designing [2, 31. With a detailed analysis of the processes machines, tools and objects these general methods were applied to the class of manipulation tasks with carbide compacts. This, together with developed sophisticated manipulation system represents a step forward towards the general solution of the manipulation problems with small and intricate compacts made from iron powder, ceramic materials, carbides, ferrites and similar materials. 2. PROBLEM ANALYSIS

The manipulation with compacts in the production of carbide inserts in their green state includes picking of compacts out of the tools and their placing to sinterring trays where they have to be accurately positioned and oriented to be optimally packed. Here one must take into consideration the following two groups of very strict requirements: - due to the low level of hardness and very complex and sensitive geometry there exists a great possibility to domage the compacts so they have to be reliably and precisely picked and placed according to specific surfaces, and - due to the complex motion of tools, the available space for picking of compacts is very small and the time allowed for picking and taking out of tools very short because of the short time cycle of presses. The existing manipulation systems cannot be efficiently applied in companieswithwideassortment production programs and small launch-

Annals of the CIRP, Vol. 40/1/1991

Such an analysis set up and carried out in detail of compacts manipulation tasks has shown that we deal here with a very complex problem and that the manipulation system has to fulfill the following complex requirements: - very short cycle times (2-6 seconds subject to the type of the press and type of the press and type of compact), - high positioning accuracy ( C 0.2 mm), - complex kinematic configuration on modular principle, - very limited dimensions of hand and gripper modules, - easy exchange of hand and gripper modules, - complex control system, - flexible and easy programming with a self set-up system according to the set task, - easy removal of the system enabling access to the tools, as well as for the cleaning, exchanges, and - high reliability. In order to illustrate the level of complexity, the available space and the time allowed for the entrance of the gripper into a tool (several last mm of the undertaken hand movement), its lowering and picking of compacts for one of critical representative parts are more detailly state. In principle the tools consist from three parts for this type of compacts. These include the upper movable holder, movable die and the lower fixed holder. The motions of the upper movable holder and the die are very complex and are represented with trajec tories 1 and 2, obtained by measurements in Figure 2. For one cycle of 2 2 , with corresponding cycle time of, for instance, tc 6 s, the die rests in its position underneath the compact during the interval of th :0.6 s. As the minimum height required for the entrance of the gripper (vacuum o r expanding arbor) into the tool is h :25 m, the time available for the entrance of the gripper into a tool (several last m of undertaken movement of the hand), its lowering and picking of the compact amounts to thl Z 0,5 s. Taking out of the compact outside the reach of the die in the worst case may begin at the same time with the raising of the die, at a greater speed, of course.

5

I

G=

The a n a l y s i s of t h e technological task

Fig. 1.

w

3. SYSTEM CONFIGURATION 110

tc

I

On t h e b s s i s of a d e t a i l analysis of the techco:ogics? t a s % , spec i f i c r e q u i r m e n t s and r r s t r i c t i m s ; tne problem was divided i n t o sevclral parts:

50

- t h e seiectlon of

30

- the

:he ooncept and d e s i g parame';ers ccnfiguraitton systev.

-

'

OOO&J 0

21 (mm) 20

do

90

'

2f0

3$0

I

'

do

5A3

440

7io

o T - ; " r , T l l ~ i I l l l l l i

Gripper i i

( 1 ,

O?

82 1 i l

1

IV,

0 1 x2 (mm) 100

07 I 12 (rnrn) 20

1

I

t

T'rg

I

I

,

I

I

I

I

L

I

,

I

I

I

, ,"

I

I

I

I

I

I

I

I

I

,

I

I

,

I

I

r

,

I

I

I

I

,

I I'

I

I

1

I

I

I

I

r

0 1

i

t

i

r

1

I

I

I

t

I

I

I

I

I

I

I

I

I

I

I

1

t

I

I

I

7

i

I

I

I

G

IYI

I

1

Gripper 2

1

0 1 ,

l

l

1

'

1

oz2

ez

1 0

I ,

1801 0 1 Table

A0

I

90

T

7

180

270

360

,

450

I

1

-

540

Fig. 2. System's tact dlagrm

6

:hoke of
- t?.e w i l d i n g ?f - t h e tes5ir.g.

imm) 3ur

1

I

I

1

630

720

3f t c e

a ?mr,ocyoe, acd

The numher of necessary degrees of freedom, short cycle time, the a v a i l a b l e space Tor picking of c c m p c t s out o f tools, accurate p o s i t i o n i n g , necessary bjpes and dimensiorn of g r i p p e r s defined t h e configuration concept of the system w i t h twin-hand mni?iAl a t o r and coordinate table, Figure 3. The cocrdinate t a b l e enables with its kinematics packirig of compacts on t h e s i n t e r r i n g trsy, thus simplifying the construction pr?perties of t h e manipulator because picking and placing posit i o n s o f compacts are fixed. i n additior, :his 8:lsws for t h e w e r iapping of gacking time wi:h other aanigulative st9ps. Together w i t h two oavic d e g e e s of freedom drivsn by s t e p mtors. the t a b l e musc have a d d i t i o n a l j rlegrees of freedom f?r the exchanqe of t r a y s , strengthened 3y p r e i m t i c cylinders.

For e a s i e r achievement of ti;e s h o r t manipulation cycle twin-hand manipulator s t r u c t u r e with f i v e clesrees of freedom m3 adopted. As thr picking and placing posit1on.s of conpacts a r e f i x e d , tken p n e ? m t i c cylinders wer? adopted a s t h o d r i v i n g power for axes X,, X2 and 0,. As the pi-king and placing l e v e l s d i f f e r wher. the t o o l s a r e ex*hanged, h o t n hands have the p o s s i b i l i t y of v e r t i c a l movement: i, and Z2 which a r e achieved w i t h %he aid of s:ep motors. T3e required p i c k i w , placing ail2 pecking Kinematics of sL1 types of compacts 1s f u l l y covered wich four e a s i l y exchangeable band aoduies M I t o M4. Compacr. shapes, t h e i r position i n twjls, possible picking and placing position surfaces d e f i n e t h r e e types of g r i a p e r !tong, Vaouum ant expar.dirg arbor! of d i f f = r s n t shape and dimensions imich a r e very e a s i l y exchangeable. 4. PtANNIhlG OF TASK AND SLSTM CoElTROL "ne planriirg of tasks 3nd system concroi a r a t e systems !Fig. 9).

:s achieved through sep-

-&sic

manipulotor structure

SlL c-

Zltzz

m&l M1

HAND modul M2

I

I

FlIl

modul MI,

3 o e zi(ez2)

I

possible

Grippers

MODULES modul M 3

manipulator's

configurations

I

vacuum

Coordinate tabk

A iY Fig. 3. System configuration

Task planning Control algorithm depends on: types of compacts and their geometrical characteristics, qeanetric characteristics of pressing tools, configuration of the nanipulatsr zype oi gripper and hand modules, and type of sinterring trays for placirq and fie node of packing. The work station sr ?C cmputer w e used for t a s k piannirq, with the prior calculation of mordi.nates and other parameters r e q u i r d for the work x" the mtn control progrun. A t present off-iine connection with the control system was envisaged wifh the aid of EPRCM integrated curcuit o r o g r m e d o n t h e w o r k s t a t i o n . ~ k e integral cirouit may contain up to 107differentprograms tasks. If greater flexibility and faster exchawe of tasks will be required during the next phase of the project, direct comnunioation connection with control system for program loading is envisaged.

-

-

-

INPUT:

OUTPUT:

-CblARACTERISTICS OF INSERTS -MANRILAlOR CONFXjLIRATICNS -CNAfWTERISTlCS OF TOOLS

-MLrNIPULAT~ C W L PROGRAM

HI

B

-

I

system control

In view of the structure of the manipulator (twin-hand manipu

-

lator and the coordinate tabla), critical time f o r the execution of certain functions (Pig. 2 ) , different actuators !electricai step motors and pneumatic cylinders), as we21 as a wide spectrum cf different sensors and pick-ups (microswitches, inductive and optical switches) the hierarchical structure of the microprocessing control system was defined (Fig. 4).

-

The control is mainly provided by: operator interface through the touch panel (referent position of the system, system set-up, choise of program, setting up of parameters subject of the toois and press, check -up of parameters and simulation of the work of the meipulator, program activition during semi-automatic or automtic rode of work), control of the manipulator (control of pneumatic cylinlers and corresponding pick ups as well as s!pchronizing of work of all other microprocessors~. The control of tne coc-rdinate table is achieved through two microprocessors one for each of the axis electrical step motors and corresponding pick ups and switches.

-

USERNTERFPCE

ODD 000 TOUCH PANEL

-

-

-

The control of the mnipuiator is achieved with two microprxessors one for each Sand - corresponding electrical step motor, pick ups and cylinders.

-

CONTROL' I' _T A_6 _L E_ _C_O N_T _R 0_L'J 'MANIPULATOR L_ _ _ _ _ _ _ _i i

Fig. 4. Task planning and system control

7

5. PROTOTYPE DEVELOPMENT

Star:Lng from t h e adooted concept... proje-t. p a r a m e t e r s arid re s t r i c t i o n s c o n n e c t e d w i t h t h e e n s t i n g s t a t e of t h e p r o c e s s , ? r e s ses and tocls, t h e p r o t a t y p e o? t h e i'iexible m a n i p u l a t i o n s y s t e m , F i i j . 5 , was d e s l s r . ~ dand developed. The c o m p l e t e s y s t e m , t h e m a n i p u l a t o r and t h e t a b l e have a compact s t r u c t u r ? b u i l t 3n 2 o x t s u p p o r t , v h i c h m y be i m t a l l e d on d i f i e r e r , t t y 3 e s 3f ? r e s s e s . The orotot:ipe x a s T e s t e d h c c h ' m d e r ;war tar'y and uorking ,:ondi>ids. -n t h i s phase af ievelopment :he s stem a c h i e v e s t h e prol u c t i v i c ; . ?? :he ~ o e r a 6 a rf a r '.ne most 3r 5 ~ t p1e s sf compacts and e n a b l e s ';he p r a s s t o uork w i t h lo-': c y c l e s p e r minute. I n r l s o n : c t n a i r p a d y developed systems a 'iery n i g h i e - i e i 3f /:ib uas achievec m t n ir. :he ?-spec- 3f iis mechanical q r a E i o n and The c c n t r o i and ;rcqnmming. 3s i t ias ?roved under ;lorking c o n d i c i c n s . & _ ^

6 . CONCLUSION Y e p a c e r d i s c u s s e s t h e comolex ?robiem 91' a u t o m a t i c n a n d l i n q of ccmuac5s d u r h g che g r d u c t i o n or' c a r b i d e i n s e r t s . Through t h e d e t a l ? r d a c a l y s x of Tne = c h i n e and t o o l p r a c e s s e s t h e c o r c e p t o f f?exiS:e s o p h i s t i c a t e d !nanipl;laticn s y s t e m was developed as xel: a s i t s p r o t o t y j e . The m e t h o d c l o g i c a ? approach t o t h s problem a s well as t h e 501u t i o n r e p r e s e n t 2 s t e p x w a r d s a g e n e r a l s o l u t i o n c f Che h a n d l i n g p r ? b l e n -f s n a i l a r d x t r i c a t e c m p a c t s m d e f r o m i r o n powder, c e r a m i c . n a t e r i a l s , ? a r o i d e s , t e r r i t e s and s i m i l a r n a t e r i a l s . REFERENCES 11

I

H i l u t i n o v i b , D., P i l i p o v i b , Y . , F r o h i e , P I . , Tapalovi'!, D., 3 r n d a r e v i d , k!. , Jevti:, M., 1 9 9 0 , F l e x r c ~ en a n i p u l a t l o n sysCem f o r c a r b i d e i n s e r t s , P r o j e c t 3 e p o r t I6 6;-9566111 ?PK15-59 juec?.ani:l: Zngineer-nq F x u i t y , Beograd

121 S i . L n . E . , New Ycru

/ ? I 'darnecke, design

331

19%.

!!echanical

k s i m o f b b o t s , PcCraw-Hill,

H.G., S c n a u f t , R.D.. 'danner, ?4,C., 1985. Mechanical t h e r o b o t system. kkndbock 3f Industrial Zobots.

kf, s., ;ohn Yiley, New York

F i g . 5. h a n d l i n g s y s t e m p r o t o t y p e

8

Acknouledgement: W e would l i l t 2 t a e x p r e s s o u r gratitude t o t h e f a c t a r y " P r n Partizan", Titovo U t r c e f o r t h e i r sLpport of t h i s work