Tl1 Conversion To Tube Cut-off Machine

[Geof]

Background To The Project

We process several thousand feet per year of stainless steel tube, cutting 16" to 30" lengths from 24' stock, facing and chamfering the ends on the ID and OD and then polishing off any final roughness with emery . Up to now the procedure was; cut with friction blade in chop saw, de-burr both ends on belt sander so tube will fit in collet, face, chamfer and polish both ends in a manual Hardinge for a total of five steps. The noisiest, most unpleasant and tedious job in our whole operation.

The decision was made to invest in a basic TL1 and use this as the platform to automate the tube processing as much as possible. The plan being to have a 20' long rotating tube carrier, an air operated collet chuck, and a bar puller able to do up to 30 inches of pull in one operation and make double pulls for greater lengths. This system will take a full 24' length, face, radius ID and OD, and part off the required lengths into a parts catcher with the second facing and radiusing operation done by manually loading the parted-off semi-finished tubes in a second operation.

[Geof]

Haas do not offer any power chuck options for the TL1 let alone bar feeds so everything is being designed and made in-house. At this time the Spring Closed Air Opened Collet Chuck shown in the pictures is in use with manual valve control.

The Hardinge website gives 1800 lbs as the optimum drawbar force for a 5C collet and this force comes from compression springs acting on one side of an air piston. It was estimated that compressing the springs to release the collet would require a force of up to 2300 lbs and with an air supply of 85 psi this would require a piston area of approximately 27 square inches. The air cylinder is an annulus to allow the tube to feed through a hollow piston carrier and 27 square inches is obtained with a inner diameter of 2.250 inches and an outer diameter of 6.500 inches. This allows the piston carrier to be small enough to enter the spindle bore slightly and for the overall cylinder outer diameter of slightly less than 8 inches to fit snug up to the spindle drive pulley in an enlarged hole in the cover plate with standard sized O-rings being used for the piston and piston carrier.

A visit to a local spring maker and a few iterations of their design program resulted in a spring design with a constant of 200 lbs per inch, a maximum compression of about 1.3 inches, a free length of 3-7/8" and an outer diameter of 1.07 inches. Ten springs could be fitted within the annulus leaving substantial webs between each spring hole in the spring carrier and allowing both the cylinder and spring carrier to be machined out of two scraps of 2-1/2 inch 6061 plate conveniently available from a local scrap dealer. As shown in the pictures the springs are pocketed in both the piston and the spring carrier to maximize the possible spring length thus reducing the piston force needed to release the collet and keeping the entire cylinder unit as short at possible.

Air supply to the cylinder is provided by a retracting air injector. The injector approach was taken to avoid designing a large annular rotating seal. The air injector is a small cylinder with a hollow piston rod and a return spring. The end of the piston rod has a trapped O-ring which protrudes approximately 0.02" and forms a seal against a brass port screwed into the cylinder. The close up picture of the cylinder assembly shows this moved away from the operating position for a clear view. When the injector is pressurized the piston moves forward, forms the seal and then pressurizes the collet release cylinder. The piston travel is limited to what is needed to form the O-ring seal so if this piston should stick while the spindle starts the only damage will be to the O-ring and possibly the brass port. The injector piston and the cylinder injection port are aligned with spindle orientation.

The 5C spindle nose is a cosmetically damaged one from a Haas Mini Lathe that the local Haas Dealer gave us which saved some machining. The air cylinder/spring holder is aluminum alloy 6061 as mentioned, the draw tube 1.50" O.D., 1/8 wall DOM tube, the piston hot rolled C1018 and all the other parts C12L14. The draw tube is lined with Delrin plastic sleeves to protect the finish on the stainless tube which is a 600 grit polish. The overall design is based loosely on the air chuck on our HL1 and has adjustment for piston stroke during release, spring compression for draw tube force adjustment and adjustable free travel on the release stroke to get an impact to assist with breaking the collet loose.

[Shotout]

Originally Posted by Geof Background To The Project We process several thousand feet per year of stainless steel tube, cutting 16" to 30" lengths from 24' stock, facing and chamfering the ends on the ID and OD and then polishing off any final roughness with emery . Up to now the procedure was; cut with friction blade in chop saw, de-burr both ends on belt sander so tube will fit in collet, face, chamfer and polish both ends in a manual Hardinge for a total of five steps. The noisiest, most unpleasant and tedious job in our whole operation.

Wicked cool. This ought to save a bit of money while freeing up some people to make more.

[Vern Smith]

That is some very nice and efficient engineering, I'm sure the design and machine work for you was a breeze.

Vern

[Kool Parts]

Nice,
Put that together in a kit, with a video of it working...then send one to some of the HFO's and watch the orders roll in

[Al_The_Man]

I just finished converting an older semi automatic Modern tube cutoff machine to CNC.
http://www.modernmachinetool.com/
The tube is loaded and measured at the trim cut and the tube is calculated to get as many pieces as possible with the remainder divided up and processed into useable short lengths to minimize waste.
A PC & Galil motion card was used for the control.
Al.

[Geof]

Originally Posted by Kool Parts Nice, Put that together in a kit, with a video of it working...then send one to some of the HFO's and watch the orders roll in

Give it three or four years so this one has accumulated several thousand operations and then we will see.

[Kool Parts]

No...no..you need to think like the big three. Come out with a product and sell it immediately..then let the motoring public do your R&D

[thkoutsidthebox]

WoW!

[handlewanker]

Hi, finally worked out how the air injector works, saves on a rotating seal for sure.
Could have done with something like this back in '98 when I had to push the hand lever 500 times in one night to clamp 1-1/4" steel bar in my 1-1/4" Taylor manual capstan lathe, makes big muscles.
In the workshop where I used to work they had the same lathe but the hand lever had a 3" diam air cylinder forcing it.
Ian.

[gizmo_454]

This all sounds like a great idea. Except, my question is, why not use the Hardinge for parting the tubes off in the first place? We have a couple of jobs where we do this. We have a split bed DSM-59 that we setup with a 20 foot, stationary, stock tube. The stock tube was then lined with two 10' pieces of PVC pipe connected together to keep the outside of the material from being damaged.

Basically, my bottom line here is this:

$20k+ Haas TL-1 and an elaborate/expensive air collet and rotating stock tube

vs.

$1k 1930's DSM-59 with at most, $100 stock tube setup

All our second op is chf the ID of the finished tubes. The OD is chf on front and back of the tubes is done in one op on the Hardinge, along with cutoff. Can hold +/-.010 OAL with rookie operator. +/-.005 all day with experienced operator.

Don't get me wrong, it's a good idea. It just doesn't sound all that cost effective to me. Just my $0.02.

Have fun with that air collet! I always wanted one for our DSM-59. Just cost too much money for our small shop.

[alain aleman]

Nice work GEOF, how cost the transformation?