HammerMonkey Posted February 6, 2018 Share Posted February 6, 2018 Yesterday I was gifted a brand new 4" bore, USA made hydraulic cylinder, by a friend. it has a 2" dia rod and a 28" stroke. it is rated for 3000 or 3500 psi (my CRS is kicking in). A 28" stroke is longer than one on any other press I could find. Someday I think I'd like to build a H frame hydraulic forging press for making hammers & Damascus billets, etc. I have been researching on the web, but there is not a lot about the maximum length of stoke. However, I did learn that the longer stroke should not reduce the power, or speed (IPS), other than it takes longer to travel the full stroke. Then there is the size consideration too as the height of the H frame would have to accommodate the longer stroke (so I wouldn't have my lower die positioned at knee level...). And I am sure that a taller press frame would need to be extra stout to resist flexing. If I were to use this ram with a 15 GPM pump I calculate that my extend speed should be about 4.6 in/sec and retract speed 6.1 in/sec. And a 11 GPM pump would net me 3.4 and 4.5 in/sec respectively. At 3000 PSI the pressing force would be a little shy of 19 tons. After a lot of digging, I could not find some answers though. 1. Does a hydraulic cylinder have to cycle fully each time it changes direction? A fast ram speed would be wasted if it had to go all the way in and out each time I pressed on something... 2. If so, could this be alleviated with plumbing design (switches/valves/etc?) 3. Does the longer extension dimension pose a greater danger of catastrophic failure of the shaft or other components under load? I would think that if I didn't exceed the PSI rating, the ram would operate within its design capacity, but... it does seem a little scary! 4. Are there any other considerations I am missing? I am thinking that this ram may work out if I can design & build a suitable frame for it. Any thoughts and opinions are welcome. Thanks Quote Link to comment Share on other sites More sharing options...
genesaika Posted February 6, 2018 Share Posted February 6, 2018 I spent roughly 10 years as a heavy equipment mechanic specializing in all forms of cranes. While I can't help much with the design, I can answer your questions. 1) No it does not, infact fully extending them can cause damage to the seals. The design of your cylinder with determine it's effectiveness though. They have 2 common designs; one that releases pressure by draining the tube, and one that uses reverse pressure to push the fluid out, ideally you would want the later. 2) see the first answer 3) so long as you stay within the specs you should be fine. I have worked cylinders out of specifications and never seen one break, the specs usually allow for 10-25% overload. That being said a shorter stroke will allow for higher output. 4) I would have to agree with you. My suggestion would be to go over the seals, or have someone do it, and maybe add a guard to the side you will be on. As a side thought for you or anyone more knowledgeable, would it be possible to put the cylinder on the bottom? The anvil would have to be over-engineered and the whole frame would have to be well secured. Quote Link to comment Share on other sites More sharing options...
HammerMonkey Posted February 7, 2018 Author Share Posted February 7, 2018 I believe this is a dual action cylinder. It has a port at each end (to drive the shaft out and in?). Yes indeed, I intend to build it with guards to protect me from high pressure failures. I work around hydraulic systems on large commercial aircraft and have seen the damage a pinhole leak in a high pressure hydraulic system will do to human flesh... The ram is brand new. Do you think it needs servicing or inspection? It looks pristine on the outside. Many hydraulic presses are designed with the cylinder/s on the bottom, to press upwards as you suggest. I personally have never cared for that design. I’d rather have my work resting on a stable, unmoving anvil, with the ram moving downward to make contact with the work. Thank you for your insight! Quote Link to comment Share on other sites More sharing options...
BeaverNZ Posted February 7, 2018 Share Posted February 7, 2018 When a hyd rams design pressure is exceeded with a well sourced component, modern design ram usually the worst that happens is the internal piston seal is extruded past the piston and this can happen on just one side which loads the piston against the cylinder wall and causes scoring. Its best to have excess stroke and not use the full stroke extenstion as this helps support the ram shaft from getting kicked out and bent Cheers Beaver Quote Link to comment Share on other sites More sharing options...
genesaika Posted February 7, 2018 Share Posted February 7, 2018 If it has sat idle for any extended period of time the seals can also be bad. Unless you can get a history on it I would get it inspected before putting it into use. Edit: if it has a port on either side then yes it is dual action. Usually they will have valves and plumbing between the ports. Quote Link to comment Share on other sites More sharing options...
HammerMonkey Posted February 7, 2018 Author Share Posted February 7, 2018 1 hour ago, genesaika said: ...Usually they will have valves and plumbing between the ports. Internally?, or are you talking about on the exterior of the ram? ‘This cylinder has nothing attached to the ports at this time. Quote Link to comment Share on other sites More sharing options...
genesaika Posted February 7, 2018 Share Posted February 7, 2018 The parts im talking about are external. Can you possibly provide a picture? I might be able to tell you more. Quote Link to comment Share on other sites More sharing options...
HammerMonkey Posted February 7, 2018 Author Share Posted February 7, 2018 I will try to get a picture tomorrow. Thanks Quote Link to comment Share on other sites More sharing options...
CMS3900 Posted February 7, 2018 Share Posted February 7, 2018 1. The cylinder doesn't have to fully retract each time you want to stop applying power. It's really dependent on how you plumb the system. 2. The simplest way to plumb it so it won't have to retract all the way is to use a regular hydraulic valve. You pull the lever, it comes down (or up if the cylinders on the bottom), squish, and then pull the lever till it's backed off enough to move the part and then repeat. There are other ways with limit switches ect.. to set the retraction height as well but that gets into more money. 3. Having a longer cylinder is a advantage over many presses, not a disadvantage. You can keep more of the rod inside the cylinder which makes the rod less likely to bend or flex during side loading, which can occur depending on your press design or where on the dies you are pressing. I think my cylinders are 24" long, and I plan on making my "press zone" about half of that, so half of the rod will always remain in the cylinder. 4. Consider that you want your work at a comfortable height, and design the press to accommodate it. Check out Randy McDaniels Press on youtube, and if you can get your hands on his book it goes over a lot of the basics. Also, look at a bunch of presses and find a good interchangeable die system you can fabricate. Quote Link to comment Share on other sites More sharing options...
HammerMonkey Posted February 7, 2018 Author Share Posted February 7, 2018 Thanks CMS, that’s the info I was looking for (and what I hoped to hear). Quote Link to comment Share on other sites More sharing options...
HammerMonkey Posted February 9, 2018 Author Share Posted February 9, 2018 This is it... Quote Link to comment Share on other sites More sharing options...
genesaika Posted February 9, 2018 Share Posted February 9, 2018 Yup, you will need a valve some plumbing and a control for it. On the plus side it looks to be in great shape and the wipper seal looks to be in good shape. Have you seen the ram? If not you can pull the plugs, pin the bottle side to something heavy, and pull out the ram. Look for any rust or dings, the entire ram should be clean and shiny or it will destroy the seals inside. Beyond that I would have to open it up to tell you more. If it were me I'd look at swapping that clevis for the bar side, because I prefer it that way, but it shouldn't make too much difference. Quote Link to comment Share on other sites More sharing options...
HammerMonkey Posted February 9, 2018 Author Share Posted February 9, 2018 Yes, the paint is scuffed up a bit from transport, but it is newly manufactured and never used. A local heavy equipment manufacturer buys sone type of component that comes with this cylinder attached. They remove and replace them with a different sized cylinder before attaching the component to the machine they are fabricating. I guess they get several of these in each year. My fried works there and offered me one when I told him what I’d like to do. Pretty good deal as this ram retails for about $400. the specs say: 3000 PSI 4” bore 2” rod 28” stroke Skived, honed tubing Heavy duty welded construction Chromed, ground and polished piston rod will operate at full pressure through 16 inch stroke Cast iron piston, cast steel butt, gland and clevis Loaded u-seal and urethane wiper gland, u-seal piston Stroke control may be installed on 8 inch strokes i am not sure what that all means. Does the 16” stroke comment mean that after the first 16” of extension, the power of the ram is reduced?file Quote Link to comment Share on other sites More sharing options...
genesaika Posted February 9, 2018 Share Posted February 9, 2018 I would say yes, the optimal stroke is between 16 inches. Once you get past that the pressure will reduce, but it's not a huge decrease, I would say that your cylinder might get to 2500 psi at full stroke. As mentioned earlier though, it would be ideal to keep it below half stroke. Quote Link to comment Share on other sites More sharing options...
HammerMonkey Posted February 9, 2018 Author Share Posted February 9, 2018 Thanks, then that actually allows 14” of stroke which is not bad for handled tooling and big stock.. Quote Link to comment Share on other sites More sharing options...
BeaverNZ Posted February 9, 2018 Share Posted February 9, 2018 1 hour ago, genesaika said: I would say yes, the optimal stroke is between 16 inches. Once you get past that the pressure will reduce, but it's not a huge decrease, I would say that your cylinder might get to 2500 psi at full stroke. As mentioned earlier though, it would be ideal to keep it below half stroke. Stroke length has nothing to do with the tonnage produced Quote Link to comment Share on other sites More sharing options...
HammerMonkey Posted February 9, 2018 Author Share Posted February 9, 2018 17 minutes ago, BeaverNZ said: Stroke length has nothing to do with the tonnage produced 1 hour ago, Shady McGrady said: the specs for this cylinder read: “Chromed, ground and polished piston rod will operate at full pressure through 16 inch stroke” Wouldn’t the comment from the spec for this cylinder (above) imply that pressure is reduced by some amount after the first 16” of stroke? If this is so, wouldn’t the tonnage produced be reduced as well? Albeit, the reduction may be insignificant, as genesaika suggests. Quote Link to comment Share on other sites More sharing options...
BeaverNZ Posted February 9, 2018 Share Posted February 9, 2018 The tonnage produced is dirrectly related to the pressure put into the ram, For the pressure to accumulate there has to be a resistance to the rams movement. What the above statement MAY be refering to is if the ram is used unsuported in like a press then to prevent kickout of the ram shaft getting bent the pressure needs to be reduced but Im only guessing there, I susspect that that statment is for a ram constructed to have a 16 inch stroke total. As long as the ram pivot or mounting points are in line with the centre line of the ram and free to move a ram with a 28 inch stroke should be ableto be used to its full design pressure for the full stroke. All this info should be freely available online if you look Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.