High-temp Material Handling Challenge

[eaglewood]

The objective: Reach about 10’ horizontally into a 1300F furnace, and pick up a 140lb rectangular container, then pull the container back out of the furnace and place it on the ground, about 2’ down.

It might help to picture a pizza oven. Reach into that hot environment, retrieve a pizza (only it’s rectangular, 140lb, and 20” tall), and place it on the counter.

I’ve already got mechanical designs that are functioning fine. But the idea here is to improve it and set it up for a possible automation project it in the future.
A sort of robot arm that can withstand high temps is the current interest. But I’ve not worked with robot arms before, and also there may be some other ways to achieve the design objective.

 

[A_G]

I saw something like this at a customer site once. They had a PLC controlled loading cart or trolley. There was an operator pushbutton station. They would press a button and the cart would move into position. I don't remember the details.

Maybe you can split the functionality up into several pieces. Press a button to move the load cart horizontally to the furnace until it sees a limit switch. Press another button to have it move vertically downwards or upwards. Press another to have it move inside the furnace and slide under the load. Then do everything in reverse.

 

[A_G]

I forgot to say that this customer had load cart running on rails on the floor

 

[lfe]

A mechanical engineer should carefully examine and calculate this. Supporting 140 pounds at a distance of 3 meters at that temperature is not easy at all. That arm should be robust.

Temperature lowers the resistance of metals and temperature differences between parts of the piece generate stresses that can cause permanent deformations.
Although they are small deformations, due they are repetitive cycles, they can ultimately create a large deformation.

Even more so taking into account that stainless steel will surely be used, which expands a lot with temperature.

If I were the designer of the oven I would study the use of a conveyor belt, there are belts that can withstand that temperature perfectly.

Also those carts, modified, can pass directly inside the kiln, many kilns work this way, perhaps handling would be much simplified

... I spent 20 years working on kiln design...

 

[Ron Beaufort]

many years ago, I heard a joke (but then again, maybe it wasn't a joke) about a project like this ... the gripper on the robot arm kept getting soft from repeated trips into the furnace ... eventually it got too soft and would start dropping the hot ingots ...

the engineers in charge went away to huddle and tried to come up with some new type of bamboosium alloy that could withstand the intense heat ...

while they were away, the maintenance mechanic installed a large galvanized tub of water next to the robot ... he changed the program so that after every cycle the robot would stick its hand into the tub for a quick cool-down ... problem solved ...

probably just a joke – but then again, maybe not ...

peace to all ...

 

[drbitboy]

many years ago, I heard a joke (but then again, maybe it wasn't a joke) about a project like this ... the gripper on the robot arm kept getting soft ... bucket of water ...

Doesn't sound like a joke to me.

 

[eaglewood]

A mechanical engineer should carefully examine and calculate this. Supporting 140 pounds at a distance of 3 meters at that temperature is not easy at all. That arm should be robust.

Temperature lowers the resistance of metals and temperature differences between parts of the piece generate stresses that can cause permanent deformations.
Although they are small deformations, due they are repetitive cycles, they can ultimately create a large deformation.

Even more so taking into account that stainless steel will surely be used, which expands a lot with temperature.

If I were the designer of the oven I would study the use of a conveyor belt, there are belts that can withstand that temperature perfectly.

Also those carts, modified, can pass directly inside the kiln, many kilns work this way, perhaps handling would be much simplified

... I spent 20 years working on kiln design...

Thanks for this Ife, I hadn't considered the deformations possible with repeated exposure to those temps. We've got a pretty robust lever arm constructed of cut 1/2" steel plate, reinforced with plenty of gussets. So far, so good. But for how long?

Also, I'll look into high-temp conveyors. Bringing the containers out to the edge of the furnace would eliminate or at least minimize the need to reach deep into the furnace to grab that container.

 

[lfe]

Thanks for this Ife, I hadn't considered the deformations possible with repeated exposure to those temps. We've got a pretty robust lever arm constructed of cut 1/2" steel plate, reinforced with plenty of gussets. So far, so good. But for how long?

Also, I'll look into high-temp conveyors. Bringing the containers out to the edge of the furnace would eliminate or at least minimize the need to reach deep into the furnace to grab that container.

Many gussets with many welds that generate tensions, which can be released and deform the structure when heated.

It seems to me that it would be more appropriate to use forks like those of a forklift, thick and solid enough.

 

[drbitboy]

Adding cooling to the lever, e.g. water flowing through tubing/piping in contact with, or through channels within, the structural parts when it's in the furnace, would lessen the effects of thermal cycling.

Actually, that may be too complex; some thickness of refractory insulation might be as effective if the time in the furnace is short enough.

 

[lfe]

Another system widely used in kilns, when the load goes in a standard-sized container, is that the containers push each other, with a pusher at the entrance, and sliding on guides on the floor of the kiln tunnel.

This can greatly increase production capacity

 

[johnd_125]

You didn't say how often you must reach in to get the container? That will determine how hot your retrieval arm gets and whether you need to do something with alloy steel or extra cooling.

In the interest of keeping it simple, is your arm just a fork type device that goes in and gets the container, lifts it slightly and pulls back out? You would only have one axis of motion, up and down.

Or must a gripper be involved? Obviously the fewer motions and linkages involved the better. I've seen robots with a ladle, dipping 1300°F molten aluminum, all day long. They hover over the molten aluminum when not in action so they get hot. Their tooling allows the motion actuators to be back a bit from the heat and I believe they have some forced air cooling routed to heat sensitive areas.

The 140 lbs at 10' is putting about 1400 lbs of torque on your base. Thats not counting the weight of your arm. Overall thats not much of a load. A small fork truck can handle that.

Let us know what you come up with!

 

[ndzied1]

Might be overkill for what you’re doing but the forging people use something like this.

https://www.cascorp.com/americas/en/forgingmanipulator#ath

 

[jstolaruk]

I was involved with the automation to handle monster ingots of just-melted copper, every component had to be capable of plant supplied chilled water cooling.

 

[eaglewood]

Another system widely used in kilns, when the load goes in a standard-sized container, is that the containers push each other, with a pusher at the entrance, and sliding on guides on the floor of the kiln tunnel.

This can greatly increase production capacity

Yes, they are standardized containers. Guides to control and route production inventory is a good idea. Right now the throughput volume is not high, but still even a small track or, if there is such a thing, a high-temp turntable would be useful.

 

[eaglewood]

Might be overkill for what you’re doing but the forging people use something like this.

https://www.cascorp.com/americas/en/forgingmanipulator#ath

This would be perfect if it was about 1/10th the size.