Week 7:- Base Unit Design Challenges 1
Base unit.
Base unit is unit used for locating clamp units ,pin units and rest units on it so that they can easily support the welding assembly properly.
the base unit also has the other miscellaneous units on it like trunking cable unit,Pneumatic valve unit,etc on the base unit.
the different parts of base unit are as follows.
The different parts of base units are.
1.Base plate.
it is generally a 25 to 40 mm plate made of SS or aluminium to support the units of fixture and to give a proper base.
2.pedestal.
A pedestal is part which connects base plate to the floor and properly transmit its load downwards properly.
3.Trunking Channel.
It is generally used to guide the various cables of biw units and the sensor cable into it.
4.Valve Box.
it is unit where pneumatic valves are kept a specified location is given for it.
5.Eye Bolt.
Eye bolt is generally used for fork lifting of the unit or the assembly properly so that it can be lifted properly.
6.Floor Plate.
floor plate are joined to pedestal so properly balanced it by increasing the surface area.
2.Points to be taken into account for design of base unit.
Working Height.
It depends on the nature of robotic operation. for manual fixture we need to carry out welding operation at welding height of 850-1100mm.
1.In these case we provide additional leg structure which may be top plate welded on it.
2 As designer we should know how big the plate or bigger base welded structure be handled.
3.A base plate can be designed with B.C.S system.
4.A base plate size should come all the unit its outer peripheryincluding operation.
5.A base plate is designed measuring holes with pitch of 1000mm in general.
6.number of datum holes depends on size of plate.
7.datum holes should be drilled at 1000 mm pitch.
8.datum holes should be covered with cover plates.
2)Dump unit.
dump unit is where you have to assemble component if you have certain constraint.here you will have cost constraint and space constraint and you cannot assemble in normal way.dump unit assembles it in different way.it consists of dump cylinder to perform the operation of clamping and unclamping in different way .The first dump cylinder is clamp ,myler and pin to perform the operation.
functions of dump unit.
1.to ensure proper resting of the panels and restrict its motion.
2.to ensure that there is no rotation of the panel and to fix it either way.
3.to ensure that it has enough clamping force.
4.dump unit should be correct shimming.
5.the dump unit can have slide cylinder and clamp cylinder.
6.calculaton are done force exerted by cylinder is checked.
3)slide units are used for positioning the fixture ,weld guns and robots into a position properly
robots into the positions as foloows.
1.hardened guide ways.
2.LM guide ways.
Slide movement prime mover.
1.Manual Slide.
2.Hydraulic slide.
3.Pneumatic Slide.
According to angular position.
1.Horizontal.
2.Vertical.
3.Angular.
Points to be considered while designing slide units.
1.L.M guideways are preferred over hardened guideways,due to least friction.
2.slide units essental of LM guides,front and rear end
3.centre trunion,rear clevis cylinder.
4.reverse stroke.
5.LM guides.
6.shock absorbtion.