Andron4000 HW crusher build

[Andron4000]

Hello Roboteers,

We are a team of engineers planning to build a crushing robot for Robot wars 2017.
We originally intended to build for this season, but due to the time constraints this was not possible, so we started work on next year.

Since we have started we have decided on the main concept of the robot, a two stage piercing arm.
We have done some testing with a manual hydraulic press to get an idea of some forces, and hope to generate 6 tons at the tip of our weapon.

There will be a typical hydraulic piercing arm set up mounted on a pivot, driven by an electric motor.
The First stage will be an electric driven jaw like arm, with a vertical piercing spike.
The idea being that this will act as an axe, (and double as a self-righting mechanism) so that the second, slow and powerful stage can act.
The hydraulic cylinder mounted on the electric arm will have a shot bolt to lock the hydraulic movement from overpowering the electric motor.

Our drive motors will be placed on order at the end of this week, and the plan is to mock up a chassis to figure out the drive system and identify any problems before the full design is finalised.

For the drive system, we are going for the NPC-T64, planning to run at 33-36V
http://hobby.npcrobotics.com/store/npc-t64/

Controlled by the Ampflow Dual motor speed controller, rated at 160A per channel
http://www.ampflow.com/motor_controller.htm

We are currently planning on running the weapon system at a higher voltage than the drive.
For the electric motor arm, we were planning on ordering the Ampflow A28-400-F48-G, the fan cooled 48V motor and gearbox controlled by the Ampflow VEX speed controller. This will have to be geared down further for use on the ‘axe’ arm.
http://www.ampflow.com/ampflow_gearmotors.htm
http://www.ampflow.com/vex_motor_speed_controller.htm

We are only purchasing a single Ampflow A28-400-F48-G initially, and are hoping that the motor can be used for the hydraulic pump, which we have not yet been able to find.

The next components (we think) we need to get the rolling chassis working are the RC transmitter/ receiver and batteries.
I currently think that LiPo are probably the best option?

Can anybody recommend any makes/ models and UK suppliers?

Any thought are greatly appreciated, as we are the first to admit that we are not quite sure what we are doing.

Thank you!

Tom

[joey_picus]

Well, you certainly seem serious about it, so good luck and gods bless all who sail in you

I'd guess that about 90% if not more of UK machines using lipos get them from one of two places; OptiPower through the FRA's discount scheme, for high-end proven performance that you get what you pay for, or Hobbyking for the rest of us plebeians - both can deliver in the UK. Treated well and specced properly I'd imagine the cheaper batteries will do just as well, but I'll let everyone else weigh in!

I think I can visualise the weapon (I'm thinking The Kraken from series 7 but with the extra claw mounted directly to the first one?) but a sketch or drawing or CAD always helps with these things.

[jonophilpott]

I have a hydraulic set up here off a tail lift if any interest maybe?

[maddox10]

LiPo batteries are probably all made in China atm.
Rebatched and upmarketed in the UK, yes, that is possible.
But team RCC is using the "cheaper" Hobbyking Zippy and Turnigy brands for years now. And we're still not disappointed.

[daveimi]

If you're not 100% sure of how a heavyweight hydraulic crusher goes together, you maybe better starting with something simpler and working up to it. What you're attempting is about as complicated as it gets.

[Andron4000]

Hello,

I agree it's a pretty ambitious concept
We have the support of our engineering company, and we specialise in machinery, so are confident on the mechanical aspects. As for the electronics and hydraulics we are not so familiar, but are all willing to learn and hope you guys can help us

IMG_7261.jpg
This is a quick sketch of the 2 stage concept, the red part being the electric motor, and the green square the shot bolt
I am thinking the hydraulics can possibly run a small cylinder for the shot bolt.
We have contacted a few companies regarding specs for the pump and are waiting to hear back

The motors and speed controllers went on order yesterday, so in the month lead time we hope to purchase the batteries and RC unit so we can get a test chassis up and running.
The OptiPower discount looks like an awesome deal, so will probably go through them.

Is there anything we are missing in terms of having a working test chassis?

LZYM3835.JPG RGAX9006.JPG
These are some of the test pieces we have experimented with to get to grips with some of the forces we need to work with.
The claw was a test laser cut piece to fit in the manual press to try a pierce then slice type of approach, but it failed pretty quickly.
primary arm.JPG
We modelled up an arm to FEA and get an idea of weight and managed to get down to 18kg with an 8tonne force at the tip and 40mm alu.
The distance from pivot to tip is 500mm and that is a m20 nut on the top for scale.

[epicentre]

How is the arm going to lock in place if the shot bolt doesn't line up with any of the holes (which it is likely not to)? Also, that bolt is going to be under enormous shear force, especially being that close to the centre of rotation. I really like the idea of a two stage axe/crusher, but think you need a different way of locking the rear arm to the chassis that is both far stronger and will work no matter what position it's in.

[Andron4000]

The cylinder can be mounted on the chassis and can be used to articulate a larger bore shaft capable of taking the load in its own housing so that the cylinder does not take any side loading.
In regards to the alignment with holes, as long as it is acting while the large cylinder is pushing, the arm will overpower the electric system and the the shotbolt will locate into the next hole.

[jonophilpott]

image.jpgimage.jpg

Any good?

[maddox10]

That looks like an Iskra motor on a double direction pump and a spring operated directional bleed valve to relieve the pressure on the pump seals. In short, a customised lorry setup.

Easy to use, easy to find, not idiotic in expensive, even new. But limited in pressure. Most of those units have a limit on 175 bar.
And weight is another issue there. That Iskra is a very tough motor, but is heavy compared to the current brushless motors on power output.