US4402497A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for unstacking a pile of sheets
Assignee: WUFAG AG A CORP OF SWITZERLAND
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Filing: 1981-10-05
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Granted: 1983-09-06
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Expires: 2001-10-05
Abstract
Abstract An unstacking apparatus comprises one or more sheet-entraining drums each having a peripheral depression, lying behind a rising forward edge, onto which the first sheet of a confronting stack is pulled by suction cups during every drum revolution. A counterpressure roller osscillatable about the drum axis is then swung from a position downstream of the depression past its forward edge, against the sense of rotation of the drum, to engage the pulled-off sheet and deliver it to a conveyor. Each counterpressure roller is spring biased toward the associated drum but is prevented by a stop from reaching the bottom of the depression in the absence of an entrained sheet. A sensor on the drum shaft or on the roller shaft emits an alarm signal whenever the distance between these shafts deviates from a predetermined range limit.
Inventors
- 👤 Kurt Weibel
- 👤 Walter Wursch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:51
CPC Classifications
B; B65; B65H; B65H3/00; B65H3/08; B65H3/0808; B65H3/085; B65H3/0858; B65H3/0866
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
206 words
An apparatus for unstacking a pile of sheets, comprising: a drum on a first shaft rotatable about an axis, said drum having a generally circular peripheral outline with a depression bounded by a forward edge farther from said axis; stationary guide means for advancing a pile of sheets to be unstacked in a generally radial direction toward said drum; pick-up means synchronized with the rotation of said drum for detaching a sheet proximal to said drum from said pile and introducing a marginal portion of the detached sheet into said depression; a counterpressure roller confronting said drum on a second shaft parallel to said first shaft, said second shaft being movable relatively to said first shaft in both the radial and the peripheral direction of said drum; and operating means synchronized with said pick-up means and coupled with said second shaft for peripherally displacing said roller in the direction of rotation out of line with said pile prior to the detachment of a sheet by said pick-up means and thereupon displacing said roller in the opposite peripheral direction past said forward edge into a position overlying said marginal portion, said second shaft being provided with biasing means urging said roller toward the sheet portion overlain thereby.
Claim 2
Independent Claim
206 words
An apparatus for unstacking a pile of sheets, comprising: a drum on a first shaft rotatable about an axis, said drum having a generally circular peripheral outline with a depression bounded by a forward edge farther from said axis; stationary guide means for advancing a pile of sheets to be unstacked in a generally radial direction toward said drum; pick-up means synchronized with the rotation of said drum for detaching a sheet proximal to said drum from said pile and introducing a marginal portion of the detached sheet into said depression; a counterpressure roller confronting said drum on a second shaft parallel to said first shaft, said second shaft being movable relatively to said first shaft in both the radial and the peripheral direction of said drum; and operating means synchronized with said pick-up means and coupled with said second shaft for peripherally displacing said roller in the direction of rotation out of line with said pile prior to the detachment of a sheet by said pick-up means and thereupon displacing said roller in the opposite peripheral direction past said forward edge into a position overlying said marginal portion, said second shaft being provided with biasing means urging said roller toward the sheet portion overlain thereby.
Claim 3
Dependent Claim
35 words
An apparatus as defined in claim 1 wherein said second shaft is slidably mounted on a plurality of supporting arms fulcrumed on said first shaft, said biasing means comprising springs carried on said supporting arms.
Claim 4
Dependent Claim
44 words
An apparatus as defined in claim 2 wherein said supporting arms are provided with stops limiting the displacement of said second shaft toward said first shaft to a minimum distance at which said roller is radially spaced from the lowest point of said depression.
Claim 5
Dependent Claim
26 words
An apparatus as defined in claim 3 wherein said supporting arms have threaded portions traversing said second shaft, said stops being nuts engaging said threaded portions.
Claim 6
Dependent Claim
26 words
An apparatus as defined in claim 2, 3 or 4 wherein said operating means comprises a cam-controlled linkage articulated to free ends of said supporting arms.
Claim 7
Dependent Claim
32 words
An apparatus as defined in claim 2, 3 or 4 wherein said pick-up means comprises a plurality of cam-operated bars carrying suction cups, said bars being axially offset from said supporting arms.
Claim 8
Dependent Claim
28 words
An apparatus as defined in claim 1, 2 or 3 wherein said forward edge is part of a radial shoulder rising from a leading end of said depression.
Claim 9
Dependent Claim
29 words
An apparatus as defined in claim 1, 2 or 3 wherein said depression is a flattened zone of the drum periphery extending along a chord of said circular outline.
Claim 10
Dependent Claim
34 words
An apparatus as defined in claim 1, 2 or 3 wherein said shafts are horizontal, said guide means comprising a sloping shelf approaching a descending side of said drum near a horizontal midplane thereof.
Claim 11
Dependent Claim
45 words
An apparatus as defined in claim 1, 2 or 3, further comprising sensing means on one of said shafts for determining the proximity of the other of said shafts and emitting an alarm signal upon the separation of said shafts deviating from a predetermined range.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-09-05 | 1987-03-07 | 1987-09-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-05 | 1991-03-07 | 1991-09-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-05 | 1995-03-07 | 1995-09-06 | $7700.00 | Window Closed / Lapsed |