Pick-n-place thread in DIY-CNC group archive was Re: Robotic Arm

Hello,

About mid last year (AIRC) we had a YERY detailed, actively
attended, and thorough discussion of the coarse and fine points of
PNP design and implementation over at the DIY CNC yahoo group. Many
of the experts of various CNC-related forums chimed in. It was a
pretty good thread...

Might be worth a look?

http://groups.yahoo.com/group/DIY-CNC

Ballendo


-- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mark Vaughan" <mark@...>
wrote:

>
> I haven't built one, but I have just bought one for smt pick n

place.

>
> Perhaps a description might help some of you.
>
> It has four axes and lots of fiddly bit.
>
> On the right hand side of the machine is a long linear carousel

that holds

> all the parts on reels. The carousel moves along the Y direction

of a mill.

> As each part is moved past the pickup point, a pneumatic plunger

can be

> raised to advance that part. The reels have tapes holding the

parts, the

> sides of the tape are punched like photographic film, and an

adjustable

> ratchet mechanism advances each part if it actuation lever is hit

by the

> plunger.
>
> The PCB table sites to the left of the parts carousel, it also

only moves in

> the Y direction. It is independent of the carousel so both can be
> positioning themselves at the same time, but for a slower machine

they could

> be allowed to move together.
>
> The pickup head moves in the X, and Z direction. It holds the part

with

> vacuum, on a nozzle, a bank of nozzles are mounted on the back of

the PCB

> table, and it can automatically select the correct nozzle for the

component.

> Two pairs of tweezers at 90 degrees to each other also meet with

the part to

> position it. The tweezers are cut with steps in them and can be

moved in the

> Z direction to decide what part they are going to grip with.
>
> For all parts the vacuum pressure is adjustable, the pressure the

head

> places down on the part to pick it up, the pressure it presses it

down onto

> the PCB.
>
> There are also syringes for glue and solder paste that are

operated by a

> controlled plunger on the head.
>
> Theres are also cameras, and error checking software that checks

the place

> part matches with the picture in memory.
>
> The pickup vacuum has a sensor to check whether it has actually

grabbed a

> part.
>
> IC chip parts holders have the chips in alloy channels with

vibrators to

> rattle them down to position.
>
>
>
> I think that about it. My machine is a 90's model so not new, but

low

> mileage and came at a good price. The manufacturer claims 4000 to

4500 parts

> per hour, but 3000 is more like it.
>
> It's quite quick, though positional accuracy is about a thou, now

where near

> as accurate as a mill, and if you get it that close, the part will

normally

> float to position by the surface tension of the solder paste when

molten in

> the oven
>
> Newer machines will to 15000 plus parts per hour, many have

multiple heads

> to achieve this so they put several parts down at the same time.

They also

> have much better photographic recognition.
>
>
>
> Now I have one, I realise it is quite a task to build one, not

difficult,

> but there's one hell of a lot of work for a one off. Just the

parts holders

> are complex enough.
>
> Anyhow that should give you something to think about.
>
>
>
> Dr. Mark Vaughan Ph'D. B.Eng. M0VAU
>
> Managing Director
>
> Vaughan Industries Ltd, reg in UK no 2561068
>
> Water Care Technology Ltd, reg in UK no 4129351
>
> Addr Unit3, Sydney House, Blackwater, Truro, Cornwall, TR4 8HH, UK.
> Phone/Fax 44 1872 561288
>
> RSGB DRM111(Cornwall)
>
> _____
>
> From: CAD_CAM_EDM_DRO@yahoogroups.com
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of roboticscnc
> Sent: 25 March 2007 21:38
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Robotic Arm
>
>
>
> Hi Group,
> Has anyone built a robotic arm for pick & place ?
> Is it possible to teach ( digitize ? ) Mach 3 to control one ?
> Could a conversion ( Macro ? ) be used to generate X,Y,Z positions
> from X,Y,Z co-ordinates in G Code ?
> I've looked around for different software ( EMC, etc. ) but can't

find

> much info for home built machines. I've been using Mach 3 for a

while

> so this helps with the learning curve but eventually it will be

asked

> to do a routine from a PLC, in which case linux may be a better

choice ?

> Thanks,
> Glen.
>
>
>
>
>
> [Non-text portions of this message have been removed]
>