controllable single blow kinyon and KA75ish hammer

[youngdylan]

Hi All

I'm starting to play around with a pneumatic impulse generator (monostable???) to get a repeatable single blow from my Kinyon and KA75ish hammers.

Basically it gives a presettable air pulse from milliseconds to seconds in length. I use a 3 way tap to swith it into the pilot circuit. It's in series with a second pilot valve that only triggers when the treadle is fully depressed (therefore throttle fully open).

It means I stomp on the treadle, the pilot gives a controllable length air pulse and tup will return to top after the blow even with foot still on treadle. Whilst it would be useful to have a blow proportional to the strength of hitting the treadle, it's also useful when doing "stamped" designs to have a constant repeatable strength blow that doesn't rely on trying to control the hit to the treadle.

Still experimenting but looking promising.

Thoughts anyone? Grant?

[nonjic]

This is a very neat setup,. I went and had a nosey today at 'young mr dylans' forge,. and whilst I cant begin to understand the air schematics I fully understand the benefits of a nice solid single repeatble blow. !

The 'KA' style hammer Davids built is also very nice, and with the 'auto cycle' feature a much more versatile forging hammer than 'one tap / one blow'. It also looks like it wants to be 'fed' hot metal, as some hammers occasionally do ! :D

[Nakedanvil - Grant Sarver]

I've played with pneumatic oscillators and with electric timers on test hammers. If you think about it, self-contained hammers work that way, controlled pulses of air. Steam hammers and Kinyon-style hammers use a feed back loop making them closed-loop servo systems. Self-contained are open-loop servos. Open loop requires some means to stop the ram at the top. I believe all self-contained hammers have some sort of cushion at the top. How are you arresting yours at the top? Sounds like you have what you need. Digital electric timers are much more repeatable in their settings and can be made to reset after each blow, how are you doing that?

Kool looking little KA-ish hammer.

[youngdylan]

Hi John

Thanks for the compliment re the hammers. The single blow circuit is probably more simple than I've made it sound and the the plumbing around the top of the hammer makes it look like something out of an Alien movie. There's probably way too much going on up there; tapping for blow off gun, warning light to tell me when there is pressure in the cylinders, clamping switch, single/repeat blow switch, a switchable balancing circuit/ regulator (and a very usecful arrangement to progressively switch it out as the treadle is pressed, will try to start a new thread about this) ..... could really do with some KISS treatment. Actually, of all the features, it's the clamp I find I use the least.

Grant, I'll try to run through the single shot gubbins in more detail this evening. Guess pictures and diagrams are in order, I do have a tendancy to excess verbiage! Have thought (and will probably continue to do so) about electrical control/ solenoid valves but it means both an air and an electric connection ... more to go wrong.

[NeatGuy]

I tried similar system for a pneumatic treadle hammer. A rotary optical encoder in the foot peddle sensed the velocity of the foot peddle and a plc controlled a pneumatic proportional valve which controlled the blow of the hammer. The plc converted the input from the encoder to a voltage (0-10v for my proportional valve). This system did not work as I wanted and I have since abandoned this idea.


brad

[youngdylan]

I tried similar system for a pneumatic treadle hammer. A rotary optical encoder in the foot peddle sensed the velocity of the foot peddle and a plc controlled a pneumatic proportional valve which controlled the blow of the hammer. The plc converted the input from the encoder to a voltage (0-10v for my proportional valve). This system did not work as I wanted and I have since abandoned this idea.


brad

Brad

Thanks for the input. I've also thought about going down the electrical control route but like the simplicity of the pneumatic pulse generator. The blow given is NOT in anyway controlled by the strength of the hit to the treadle (throttle) other than the treadle behaves as an on off switch that signals the pulse generator to send a short duration pilot signal to the main valve. The length of this pulse is independant of the time and strength of the hit to the treadle. At the start of the pulse, the main valve then switches over so that the tup is forced down for a short duration (dead blow) and when the pulse is "over" it switches over again and returns the tup to the top of it's stroke. The strength of the blow is "dialled in" before hand by the preset length of the pulse (fractions of seconds) or the supply air pressure.

As Grant pointed out (I think), the weakness of the design is that the tup returns to the top of it's stroke at full force if the treadle is still depressed when the pulse is over. The advantage of the design is that the blow is a dead one, no half blows, bouncy or double blows, and the blow strength is always exactly repeatable (as long as the workpiece it hits is a similar height).

The devices are relatively expensive compared to decent flow rated main valves; they probably cost about the same as a good quality roller lever operated pilot valve. NOTE, THEY ARE NOT TIME DELAY VALVES. They are only two port devices so there's a minimum of extra inexpensive pilot plumbing. However, t I haven't fully worked out the best system re the rebound bit. I can see mileage in it as a pneumatic oliver - powerhammer and am hoping for input from the many people more experienced than me. John Larson, you about anywhere?

Diagrams speak a thousand words so I'll do later.

[Nakedanvil - Grant Sarver]

Can you give me a link to information on the valve you are using, please? The ARO oscillator valve I tried was $300.00+!

A good cushion cylinder would probably have to be built custom. I'd probably use a top head with the "air in" as a center hole such that an extension of the rod could plug it and trap the needed cushion air. They make cylinders like that, but not with enough cushion for a hammer.

[youngdylan]

Can you give me a link to information on the valve you are using, please? The ARO oscillator valve I tried was $300.00+!

A good cushion cylinder would probably have to be built custom. I'd probably use a top head with the "air in" as a center hole such that an extension of the rod could plug it and trap the needed cushion air. They make cylinders like that, but not with enough cushion for a hammer.

My valve came from ebay. I'm out of the workshop now but I'll get the info I can from it later. It think its an SMC but I'm bound to be wrong.

Do you guys have RS over there. Here's a link to something that sounds similar.

http://uk.rs-online....ductNum=0725024

Looks a bit different to mine physically but seems to have the same function.

RE the rebound cushioning. It is the weak part of the design. My Kinyon was originally just conventionally plumbed but more by luck than judgement, the rebound spring I used seems suitably rated for the one shot mode.. a section of a motorcycle suspension spring.

My KA75ish is a different beastie, its is probably soemwhere around a KA50kg, but that's a whole nother thread on using the right rebound spring/ weight of tup/ available stroke. When autocycling it tops out on the top of the stroke if I let rip with it. The whole hammer can almost jump in the air (I've kinda "gas flowed" it in that I've bored out the exhaust ports on the cylinders and used the fattest/ shortest main plumbing I can). Pretty impressive given that anvil/base is getting on for 500kg. I had to increase the tup weight to slow it down, hence the strange composite design to the tup . Really am no expert on this stuff at all but I kinda think for my use I'd rather have a lighter tup run slightly faster. 1/2 m v squared and all that. As Grant says the built in cushioning in the cylinders ain't up to the job and the springs I used are too weak/short. They're sort of truck valve spring sized. Thing is my time to tinker/play is constrained by the need to use the workshop to pay the mortgage/ earn money to buy the toys to play with, so I've had to live with the springs first used.

Grant, when I built the KA75ish I looked at your design and more or less copied it (except both cylinders doing the up/down stuff). Why have you (and hence me) used two springs for the cushioning? I'm kinda wondering if I used just one for the up stroke rebound, I could have more space either use a longer beefier spring or be able to squeeze in longer stroke cylinders.

I'll try and sketch a diagram of the one shot circuit later. Why is there only 24 hours in a day?.

PS what I love about the KA school of thought is that all the mass is where its needed under the hammer blow. I wish people would wake up to the fact that the weight of a hammer frame thats not part of the anvil adds very little to the effectiveness of the blow. (makes it more stable re bouncing around the workshop though). It has made me giggle in the past with "Striker" devotees claiming it's a better hammer than Anyangs because the frame weighs more. Also really makes me snigger when people claim that "Striker" is an American and therefore better hammer than Anyang. Don't they realise they're both made in China (and there's nowt wrong quality wise with that if the quality control is there). Do they really think because the name "Striker"sounds less chinese than "Anyang" its a better hammer.

...oops, verbiage alert.

[youngdylan]

Brad

The devices are relatively expensive compared to decent flow rated main valves;

....oops (a word I use all too often). Just re read this post and where it says expensive it should say inexpensive. Silly me.

I got mine new from e bay for about a tenner but a quick look in the RS cataloque shows similar devices for around the £50 mark. 1/8 th port Norgren pilots are a lot more!

[youngdylan]

Can you give me a link to information on the valve you are using, please? The ARO oscillator valve I tried was $300.00+!

Grant

I hope this is of use

http://www.azpneumatica.com/azweb/ita/genimp.htm

Sorry it's in Italian but I'm sure it gives you the gist of things.

[Nakedanvil - Grant Sarver]

Well, if it took up on one spring, then when it released it would slam into what? There are also springs inside the cylinders to prevent crashing.

Thanks for the information, m8!

[youngdylan]

There are also springs inside the cylinders to prevent crashing.

Even when they were working, the air cushions in the cylinder weren't really up to the job. Plus which, I did way too much working cold steel (yeah i know, naughty boy me) and the shock waves must have travelled through the rods because the plastic sleeves that are part of the cushioning mechanism inside the cylinders eventually shattered.

I'm also expecting the cylinder rods to shear sooner or later where they neck down from 20mm dia to an M16 thread. This seems to be the Archilles heal of Kinyon base designs, happened a few time on my conventional Kinyon. I kinda regard the cylinders as consumables. That said I'm thinking of making a bespoke rod with no shouldering down; 20mm rod with an M20 thread on the end

I think I'll get some holes bored onto the base (130mm thick slab) that the springs can sit in. Allows longer springs/ cylinders to be used.