Swivel lock feature which allows blades on shears to separate

Question

Swivel lock feature which allows blades on shears to separate

recon1811 (Mechanical)

(OP)

7 Jan 21 18:59

Hello,

I am designing a trauma shear for the company that I work for and we are wanting to utilize a swivel lock to allow the blades to separate for cleaning.
i.e. https://shun.kaiusa.com/shun-kitchen-shears.html ; https://www.cutco.com/products/product.jsp?item=su...

I have been working with a factory in China to design and manufacture this component but they have been able to provide me with a quality prototype.
I am pretty savy in SolidWorks so I have take the initiative to design it myself. I am basing the design off the Shun kitchen shear. I have completed the shank of the swivel lock as well as the locking interface on the blade (see picture 1 below). And now I am trying to figure out how I will secure the shank to the blade. I do not understand hardware used on the Shun. Can anyone provide insight based on the 2nd picture below?

The Shun swivel lock shank and locking interface

Shank secure hardware

hydtools (Mechanical) · Answer 1 · 2021-01-07 19:06:39

Look at Cutco shears. The shank is pressfit to the blade. The nut is used to adjust the blade-to-blade tightness or clearance.

Ted

rb1957 (Aerospace) · Answer 2 · 2021-01-07 19:29:16

so the tang and the slot allow the two blades to come apart.
and the view with the nut is a different type where the tang has a thread on it, for the nut, as hydtools says to tighten the blades.

you might get teh same result with an internally threaded hole in the tang.

buy the second pic and have a look.

another day in paradise, or is paradise one day closer ?

IRstuff (Aerospace) · Answer 3 · 2021-01-07 19:48:26

I think it's the other side of the same shear

TTFN (ta ta for now)
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rb1957 (Aerospace) · Answer 4 · 2021-01-07 20:39:38

no they're two different types ... first shun, then cutco (from the links posted).

the 2nd (cutco) one may not have a tang, but just an externally threaded post, with some seat to locate the 2nd shear.

another day in paradise, or is paradise one day closer ?

IRstuff (Aerospace) · Answer 5 · 2021-01-07 21:53:24

Quote:
and the view with the nut is a different type where the tang has a thread on it,

that's the backside of the Shun

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

TugboatEng (Marine/Ocean) · Answer 6 · 2021-01-08 00:16:43

I'm not a fan of the serrated locking washer for sterile applications. There are many places for things to collect. I would suggest avoiding that design.

MintJulep (Mechanical) · Answer 7 · 2021-01-08 00:43:26

If your material has good weldability this looks like a perfect application for friction stir welding.

3DDave (Aerospace) · Answer 8 · 2021-01-08 23:25:30

The serrations are the least of the disinfection worries - the large area between the plastic grip and the metal is an extremely difficult dead-end pocket to clean properly. The plastic never bonds to the metal well enough to exclude bacteria and viruses. If they are autoclaved well enough to sterilize that area, the serrations will also be dealt with. However, there are some places that use toxic gases for dealing with plastics that cannot handle an autoclave and those might not penetrate far enough into the gap. This is one reason so much is now single use.

SwinnyGG (Mechanical) · Answer 9 · 2021-01-12 13:04:52

I own the exact pair of stainless Shun shears in the first post.

The T-post is press fit into the blade, and also threaded on the bit that protrudes. The nut is there so that as the pocket in the female blade wears over time, you can turn the nut to pull the T-post through the blade a little at a time and re-tighten the fit when it becomes loose.

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Swivel lock feature which allows blades on shears to separate