Don't know how reliable the sources are and don't know anything about stamping, but FWIW:

http://blogs.yahoo.co.jp/metal_stamping_basics/MYBLOG/yblog....
大きなクリアランス　Excessive clearance (Large clearance)

大きなクリアランスの結果としてダレが大きくなり、セン断面が短くなり、バリが大きくなります。また、ストリッピング 力（カス取り力）や、パンチ磨耗を低減します。
Large clearance result in large rollover, short burnish band, and large burr. It may reduce the stripping force
and punch wear.

パンチがダレると穴端面側のダレ、セン断面深さが増加し、抜きカス又はブランク側のバリ高さが増加します。
Dulling of the punch increase the rollover and the burnish depth on the hole edge, and increase the burr
height on the slug.

http://blogs.yahoo.co.jp/metal_stamping_basics/10503307.html
A : ダレ　Rollover　
　　角部分の小さな丸みは材料の厚みや硬さ、パンチとダイのクリアランスによってサイズが変わる。
過大なクリアランスは大きなダレをまねきます。
　　The size of this small edge radius depends upon the stock thickness, hardness, and the clearance
between punch and die. Excessive clearance allows a large rollover.


--------------------------------------------------
Note added at 11 mins (2011-01-17 02:22:01 GMT)
--------------------------------------------------

Alternatively, some sites have it as "roll-off."
http://gjiten.sourceforge.net/dictfiles/engscidic

--------------------------------------------------
Note added at 1 day4 hrs (2011-01-18 06:15:32 GMT)
--------------------------------------------------

"Rollover" and "shear drop" seem to be interchangeable:

http://www.nec-eng.co.jp/pro/document/word/word/wrd_j_ta.htm...
だれ roll over, shear droop

FWIW, "rollover" seems to be associated with stamping in all countries, whereas the "shear droop" Google hits seem to be associated mostly with Japanese companies and/or patents, in case that matters. (If you want to replicate my results, google ["rollover" "punch side"] and ["shear droop" "punch side"].

e.g. American inventors: http://www.patentgenius.com/patent/4144785.html
As the punch cooperates with the opposed die to shear material from the workpiece, the upper edge of the workpiece in the area of the removed material slot exhibits an edge depression known as rollover. This rollover, when associated with narrowelongated punches, is a phenomenon particularly associated with the longitudinal edges of the slot in the central regions of the slot. Thus rollover is minimized at the short side ends of the slot and maximized adjacent the center of the major dimensionof the slot.

When an elongated punch is used in a nibbling mode with slightly overlapping punch contacts, the differences in rollover between the central portion of the slot major dimension edge and the end portion produces a series of spaced burrs or tips. These burrs can be quite evident along the edge of material parted by this nibbling technique. Such burrs are objectionable.

e.g. Japanese inventors:
http://www.patentgenius.com/patent/5377572.html
Both cutting edges of the moving blade and the receiving blade are formed with a plastically deformed portion formed by press cutting. By ensuring that each second shear droop region formed in the plastically deformed portion of each cutting edge contacts the other second shear droop region of the other cutting edge, a roll-type paper inserted between the cutting edges can be easily cut.