Need Ideas on cutting wood

[clawmute]

Ok here is the problem. This description is longer than I like, but I don't know how to shorten it and be clear. I have to design a saw system to cut wood "scrim". This is southern pine blocks (logs) from 4" - say 10" in diameter that has been crushed into "scrim", making a mat of interconnected fibers of various sizes - please see the attached photos. I can't say much about the process because of nondisclosure agreements, but this mass will be pressed into structural wood beams similar to "paralam".

These mats are "laid up" so that they form a cross section that is roughly 48" x 48" x continuous. The sides are contained by steel plates and the bottom rests on a conveyor which is carrying this continuous mass of scrim. In an attempt to keep this mass together it has been wrapped with a "birdnetting" material (similar to mosquito netting). The cutting will be done on the fly. (conveyor is moving) The cut (top to bottom on one cut, bottom to top on the next) must be made as quickly as possible - preferably 5 seconds or less.

1. I am looking at using a special saw chain and tooth design, but it will have to be so that a minimum of short fibers are pulled out by the sawing action, and so that the netting (made by DuPont or similar) doesn't get clogged up in the saw. Programmable electric actuators will control both the downstroke of the cutting part of the system and the horizontal tracking that matches the conveyor speed.

2. I've even considered a derivation of the special diamond chains or cables used to cut through concrete structures, but am guessing that the friction + combustable wood = fire hazard. No water can be used since the whole mess has been dried.

3. Circle saws and band saw systems would be too massive to be really practical. A bar guided cutting chain of some sort is still my best first shot.

4. Pneumatic hold down shoes will help firm up the bundle to some extent while the cut is being made.

5. Have you ever looked at the special chains that are used for cuttin hay bales? I'm not convinced that they would cut this scrim since some of the pieces may be as large as say 3/4" or so, roughly round.

Trial and error with different chain/tooth designs is all I know to do. Setting up cross sections of the material (wrapped loosely with the netting) and trying to cut it. If a suitable chain design is found, it will have a bar that is guided on each end by ball bushing sleeves (like Thompson).

Any ideas? I always start with as far out of a brainstorm as my tired old cranium can dream up, and many times the most far out ends up being the most practical.

I know there are some good thinkers out there & thanks a whole lot for any responses.

Frank

Cuts will be across the grain. Individual mats are stacked on an angle to the horizontal forming a continuous mass that is about 48" square. Just imagine that what you see here is actually 4ft. wide X 4ft. deep with the individual mats at say 20 degrees to the horizontal.

Here's a little wad of the "scrim" coming down a conveyor

 

[savageactor7]

I suppose as a last resort you could fasten a sacrifical piece of 1"x (whatever) over the scrim and it would cut clean.

Then if you a big enough circular saw you could cast a chaulk line then cut it with a formica cutting blade.

 

[clawmute]

I suppose as a last resort you could fasten a sacrifical piece of 1"x (whatever) over the scrim and it would cut clean.

Then if you a big enough circular saw you could cast a chaulk line then cut it with a formica cutting blade.

With a circular saw you have a saw collar, and even if you used two (one above the 48" depth and one below) you'd still be talking about a minimum of 60" diameter saw for each. Too big considering a say 50-60hp motor for each with a frame and tracking mechanism. The whole footprint gets out of hand pretty fast!

 

[Zodiac45]

That's a tough one Frank. I'm not sure that a chain is gonna work for you due too exactly what you've already described happening with the netting etc.. Just not sure a tooth profile change will make an appreciable differance. Are you cutting for the manufacturing process or too use in some other way (such as burning). Why would you crush it in the first place unless it's structurally quite a bit stronger done that way? Anyway, I envision a circular blade myself unless there was a way too shear it? ( ie. the chomper type hydr. shear).

 

[clawmute]

That's a tough one Frank. I'm not sure that a chain is gonna work for you due too exactly what you've already described happening with the netting etc.. Just not sure a tooth profile change will make an appreciable differance. Are you cutting for the manufacturing process or too use in some other way (such as burning). Why would you crush it in the first place unless it's structurally quite a bit stronger done that way? Anyway, I envision a circular blade myself unless there was a way too shear it? ( ie. the chomper type hydr. shear).

This is a mfg process and crushing the wood allows you to reform the compiled wood into a rectangular shape. Shearing is OK for small thicknesses but 48" is way too much.

A band saw blade would have to be twisted (doable) but the enormity of a bandsaw that size is formidable and a total last resort. Circle saws are VERY large.

Trying to drag anything across that netting is like trying to drag a trotline across a brush pile and not get hung up. We may be able to leave a "free" zone where we skip wrapping at points of cut (which are about 50ft. apart)

R & D with different chains (I'm not certain what the real limitations of a cutting chain is - FPM wise - saws run up to say 15,000 rpm with chains from 5000 to 7000 FPM. Faster may be possible - don't know. There are limitations when you start looking at lubrication, friction heat, etc.

Maybe the diamond faced teeth of a chain similar to those used in dismantling/deconstructing concrete would be worth investigating. Perhaps a saw chain that has links with a saw toothed top, with alternate links pitched right and left. (like short saw blades) - sort of reminds me of a multi-pitch metal cutting bandsaw blade that has maybe an inch at one tooth pitch and the next inch at another.

The diamond cable cutting systems might be worth looking at. I've seen one that Husqvarna makes but have made no contact with them though. (Husqvarna CS 2512, http://uk.husqvarnacp.com/node1552.aspx?nid=80664&pid=9380)

Right now I'm just juggling options. Sooner or later we'll have to try it out in the shop when we get a few reasonable ways to go.

Simple = GOOD!

A small piece of finished product after it has been pressed is shown in photo below.

 

[carvinmark]

That's a tough one. Is it possible to ruff cut it larger than needed so you don't pull out the fibers and then do a clean up or finish cut after the product is all cured up?
Looks like those lambeams.

 

[RON58]

If you had a steel plate with a saw kerf in it to press down and hold pressure on the mat while cutting. The blade of the saw would have to follow the kerf in the plate. Might be hard to position? But if you try it and it cuts for ya it might not be too bad with a fixture on the thompson shafts.

 

[drmiller100]

use a shear. sheer? hydraulic knife. go look in a sheet metal shop how they work.

might consider a water jet.

 

[sawinredneck]

As others have said, either press it on both sides of the cut, and use a circular blade as a chain will "pull it" way too much.
Or shear it. Shearing is about as quick and esy as it gets for this proccess. Press one side, allow just enough clearnace for the blade, then feed in the next section.
Think K. I. S. S.!!

The only other option I can see would be to form the "beams" in a continous manner then cut them to length. Laugh, but it's been done before.

 

[Engineeringnerd]

If shearing doesn't work, consider a bandsaw action.

If you have some money, use a water knife. I know the big industrial ones can set you back $100K plus, but perhaps there is a more limited version that's a lot less. You may even be able to rent one.

 

[KsWoodsMan]

OKaaaaay ! you said far fetched ideas accepted.


A 6 1/2 foot hedge trimmer blade on a robotic arm, cutting from top to bottom. When it gets to the bottom there is a loop in the belt that drops down to form a void, for the arm to retract out of the scrim. Or just the end of one conveyer and the start of another. The arm could come out under the table.

Being on an arm the teeth will have to be curved inward, instead of straight. So it doesnt drag scrim out with it as it pulls back and down in sync with the conveyer.

Instead of a $50,000 arm , it could be built on a track above the conveyor that moved along with it and returned within 25 feet to be ready for the next cut. At the point where it finished the cut there there could be a nother conveyer that was moving 1% - 2% faster than the first to pull the 2 sections apart slightly, allowing room for the blade to retact. Or most of the time they were synced and the last 4-5 feet the next conveyor stepped up a touch to allow more room.
Or, the conveyors could come up to a peak at the point the blade/arm was to retract. It wouldn't take much just 4-5 inches over a 20ft span would give a 1" opening for a few seconds.

 

[Orange Hill]

What about a scroll saw? You can use a section of blade marginally longer then the 48" that is tensioned and reciprocates up and down as the material is fed through it.

 

[Scooterbum]

Water Jet or Laser.

 

[treeslayer]

A laser, they use them in candle manufacturing.

 

[Dan_IN_MN]

#2 No water...material has been dried

If shearing doesn't work, consider a bandsaw action.

If you have some money, use a water knife. I know the big industrial ones can set you back $100K plus, but perhaps there is a more limited version that's a lot less. You may even be able to rent one.

2. I've even considered a derivation of the special diamond chains or cables used to cut through concrete structures, but am guessing that the friction + combustable wood = fire hazard. No water can be used since the whole mess has been dried.

 

[Engineeringnerd]

A water jet would add almost zero water to the material. It's pumped through at about 1.5 buzzillion psi in a stream about the size of a hair.

 

[Dan_IN_MN]

That thought crossed my mind..

A water jet would add almost zero water to the material. It's pumped through at about 1.5 buzzillion psi in a stream about the size of a hair.

That thought crossed my mind.. I was wondering about that....

BTW....how much is a buzzillion? :greenchainsaw:

Dan

 

[Engineeringnerd]

Let me research that a little.

 

[Engineeringnerd]

After considerable research I find that a buzzillion is about twice as much as a "heap-a-lotta". Some people prefer metric, so I stuck with buzzillion units of measure.

 

[Orange Hill]

Water jets are awesome. I have seen them at work on meat, vegitables, metal, and marine plywood, but 48" might be beyond a water jets capacity. I would think the stream would decompose at this distance even at multi 100k pressures.