January 30, 201610 yr the peices tend to bend when they are produced by drop forging under hammers after the ends are heated. any way the bending can be avoided ?
January 30, 201610 yr What alloy of steel are they? How big, and what method is being used to make them?
February 3, 201610 yr When working in the Auto Parts Business, that was an ever-present problem, with forging Automotive valves. Rather than fight that losing battle, ... we just straightened them afterwards, ... by rolling them between flat plates, in a reciprocating "Thread Rolling" machine. That process can be as simple, ... or complex, ... as you choose to make it. If you GOOGLE "thread rolling" videos, you can get a perspective on how this might work. Good Luck. .
February 5, 201610 yr Author On 1/30/2016 at 5:02 AM, BIGGUNDOCTOR said: What alloy of steel are they? How big, and what method is being used to make them? we use EN8D and even chrome vanadium . The size ranges from 14" - 17" in length and 14 mm - 26 mm in diameter w.r.t. the length. And we use closed dies under drop forging hammers.(the mouth or the ends of the steel rods are pre-heated).We place the rods vertically under the hammer. On 2/3/2016 at 7:50 PM, SmoothBore said: When working in the Auto Parts Business, that was an ever-present problem, with forging Automotive valves. Rather than fight that losing battle, ... we just straightened them afterwards, ... by rolling them between flat plates, in a reciprocating "Thread Rolling" machine. That process can be as simple, ... or complex, ... as you choose to make it. If you GOOGLE "thread rolling" videos, you can get a perspective on how this might work. Good Luck. . Thank you very much sir. But the bend occurs after the forging. So basically i have to straighten out a rod with variable diameters . I understood the process but can you point me out to something that can straighten a piece with different diameters? THANK YOU .
February 5, 201610 yr D33PAM, what you want is a machine that does this, but with smooth rollers. Commercial thread forming machines are available. Whether you make it yourself, or buy it is up to you.
February 5, 201610 yr 9 hours ago, D33PAM said: So basically i have to straighten out a rod with variable diameters . I understood the process but can you point me out to something that can straighten a piece with different diameters? I thought I did, ... but apparently my poor communication skills have again raised their ugly head. An Intake valve, in an internal combustion engine, is a fairly extreme example, of a part with widely disparate diameters, ... and the distortion of the valve stem, also occurs after forging, ... during the annealing process. The photo posted above, ... by John McPherson ... is NOT the type of Thread Roller I was referencing. A RECIPROCATING, FLAT DIE Thread Roller, presses the part between 2 FLAT PLATES ... ( not rollers ) ... that are moving in opposite directions. When actually rolling threads, the flat dies have a series of "Vee" shaped grooves, that form the threads, ... but when used as a "straightener", the dies are smooth, ... with one very shallow diagonal groove. The shallow diagonal groove serves to "pull" the part down into the die, as it rolls the small diameter between the dies. This downward force causes the larger diameter of the part to be drawn down against the top of the dies, ... which "squares" it, in relation to the smaller diameter. Hopefully, that's a little clearer, ... but again, a look at a video of the process, would be useful. .
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