Heat treatment of Hinge 2

[Stezza]

I have a MS20001A-9 Hinge that is being used on a door in a galley. This is a "Piano" type hinge.

It is maunfactured from Extruded 7075-T73511.

I want to modify the hinge from the As Recieved condition by bending one leg of the hinge so the fasteners attaching it to the door are hidden from the passengers.

To make the bend at a small bend radius is it going to be possible heat treat to annealed condition, bend the leg and re-heat treat to T73.

I am concerned that the heat treatment process (expansion and contraction during heating and cooling) will affect the dimensions of the hinge at the hinge line.

For example the required concentricity of the pin hole is 0.005 inches and maybe after heat treatment it won't be possible to insert the pin into the hinge.

Anyone have any thoughts or experience about the effect of the heat treatment?

Thanks

 

[Stezza]

One clarification the hinge is going to be bent in the W condition not the annealed condition.

 

[bf109g]

Stezza -

I have some reservations about bending an extrusion parallel to the L direction, even if you have taken it to the W condition. I'd probably use a sheetmetal type MS20257 hinge if I wanted to bend a flange.

You may want to call the folks at Guden hinge and pose your question to them. They have provided decent tech support in the past.

 

[GBor]

You may pose this in the metallurgy forum as well. The materials types understand this probably better than we do.

As an alternative, you may be able to design a separate piece (plastic?) that can be attached behind your hinge and then fold over the fasteners...like the covers of toilet bolts.

 

[rerig]

Rather than bend the hinge (bad idea) you could install them as shown from a section of a Galley door drawing.
Or there are some Hidden hinges available as used in Business aircraft where the hinge is not visable at all.

 

[ornerynorsk]

Not good practice to bend parallel to the flow of the extrusion.

 

[Stezza]

Rerig, thanks for the picture, this was considered but we didn't have test data for the strength of inserts into the edge of the composite (only into the face of the composite).

I am aware its not preferable to bend an extrusion parallel to the L direction but the companies process spec for bending extrusions does not place any limits on the orientation of the extrusion when bending.

The problem I am wondering about is each tang of the hinge getting heated and cooled during heat treatment thus deflecting slightly from the initial position and then the holes in each tang for the hinge pin not being concentric anymore.

 

[berkshire]

Stezza
Distortion during heat treatment is quite common, so is specifying a hand straightening operation while the material is in the AQ condition.
B.E.

 

[WKTaylor]

Stezza...

Berkshire is correct... distortion resulting from HT will kill You.

What about...

Option A...
MS20001-9 [2024-T3511]. Cold or warm [300F] bend over a R0.19" radius... then age harden per AMS2770 to -T8511 [will provide post-bend stress relief and improve strength increase].

Option B...
Make hinge from a bulbed bar-type extrusion, such as Transtar metals "B04" profiles [Alloy per Your spec].
Make as follows...
Form in W temper (0.12BR for 0.050 thick) and straighten A/R. Age-harden to final temper [2024-T81 or 7075-T73].
Machine hinge nodes to match MS20001-9 pattern. Deburr.
Gun-drill 0.093"-Dia hinge-node holes. NOTE: will need to make (tool-steel) drill-guide for this operation.

Option C...
Machine Your hinge profile from bar-stock [alloy-full temper] Machine hinge nodes to match MS20001-9 pattern. deburr. Gun-drill 0.093"-Dia hinge-node holes. NOTE: will need to make (tool-steel) drill-guide for this operation.


Regards, Wil Taylor

 

[Stezza]

Berkshire and Wil thanks for the responses.
I am going to propose these other solutions to the designers.

 

[WKTaylor]

Stezza... Duhhhhh...

I had an incomplete statement/thought in option A... should have read as follows...

Option A...
MS20001-9 [2024-T3511]. Cold or warm [300F] bend over a R0.19" radius... then age harden per AMS2770 to -T8511 [will provide post-bend stress relief, increase strength and improve SCC resistance].


Regards, Wil Taylor