US3839958A - Removal of flexible sheets from rotary drums - Google Patents

Removal of flexible sheets from rotary drums Download PDF

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Publication number
US3839958A
US3839958A US00404686A US40468673A US3839958A US 3839958 A US3839958 A US 3839958A US 00404686 A US00404686 A US 00404686A US 40468673 A US40468673 A US 40468673A US 3839958 A US3839958 A US 3839958A
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United States
Prior art keywords
drum
sheet
cam
separating member
clamp
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00404686A
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English (en)
Inventor
A Kent
Riley K O
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Vickers Ltd
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Vickers Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41L—APPARATUS OR DEVICES FOR MANIFOLDING, DUPLICATING OR PRINTING FOR OFFICE OR OTHER COMMERCIAL PURPOSES; ADDRESSING MACHINES OR LIKE SERIES-PRINTING MACHINES
    • B41L31/00—Devices for removing flexible printing formes from forme cylinders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41L—APPARATUS OR DEVICES FOR MANIFOLDING, DUPLICATING OR PRINTING FOR OFFICE OR OTHER COMMERCIAL PURPOSES; ADDRESSING MACHINES OR LIKE SERIES-PRINTING MACHINES
    • B41L29/00—Devices for attaching printing elements or formes to supports
    • B41L29/12—Devices for attaching printing elements or formes to supports for attaching flexible printing formes
    • B41L29/14—Clamping devices

Definitions

  • rotary apparatus of the kind comprising a rotatably mounted drum provided with sheet clamping means for releasably clamping one end of a flexible sheet to the drum while the drum is rotated by drive means of the apparatus, it has hitherto been common, for example in the case of rotary duplicating machines, to remove the sheet from the drum manually after use. It is an object of the present invention to provide means whereby such sheet removal can be effected in simple manner without the need for manual operation.
  • rotary apparatus of the kind comprising a rotatably mounted drum having a circumferential surface and provided with sheet-clamping means for clamping at a predetermined location on the circumferential surface a leading edge portion of a flexible sheet whichextends around that surface, from said leading edge portion, in a given direction; said apparatus including:
  • reversible drive means coupled to' said drum and changeable between a forward-drive condition, rotating said drum in the direction opposite to said given direction, and in a reverse-drive unloading condition rotating said drum in said given direction;
  • a separating member for removing the sheet from said circumferential surface
  • a positioning mechanism supporting said separating member, movable between a non-operative disposition, for holding the separating member away from said drum, and an operative position for interposing said separating member between said circumferential surface and said sheet when said drum means are in said unloading condition; and I clamp-release means, defining a sheet-end release position for the drum, arranged to de-actuate said sheet-clamping means whensaid drive means rotating the drum in said given direction bring the drum into said sheet-end release'position.
  • the invention is applicable to the unloading of a flexible stencil sheet from the duplicator drum of a rotary duplicating machine such as disclosed in British Patent Application No. 57786/72.
  • the duplicator drum is provided with sheet clamping means adapted to grip a leading edge portion of the stencil sheet so that as the duplicator drum rorates the rest of the stencil sheet is entrained around the surface of the drum.
  • the sheet clamping means are operated so as to release the gripped edge portion of the stencil sheet before that edge portion reaches the separating member, the sheet will be drawn off the drum cornpletely. Generally, most of the drum surface will be inked for the purpose of reproducing the stencil wound around the drum. Because of the tackiness of the ink employed at the drum surface, any tendency for the inertia of the trailing edge portion of the stencil sheet to the drum surface is prevented during duplicating. So that the trailing edge portion of the stencil sheet does not itself become attached to the drum surface, a noninked, preferably metal portion of the drum surface is provided in the vicinity of the trailing edge portion of the stencil sheet. In this way subsequent separation of the stencil sheet from the drum surface upon rotating the drum in reverse is not impeded.
  • Rotary apparatus embodying the invention may also take the form of a rotary printing machine.
  • one end of a flexible sheet form printing plate is clamped by the sheet clamping means so that as the rotary drum of the apparatus is rotated the rest of the plate is entrained around the circumferential "surface of the drum and, in combination therewith, serves as a printing cylinder in the machine.
  • the plate may for example be an electrostatic or other paper-master for lithographic reproduction.
  • the separating member employed in apparatus embodying the invention can take various forms. Where the separation of a stencil sheet from a tacky inked surcause lifting of the remainder of the stencil sheet from face is concerned, however, the area of the separating member coming in contact with the inky undersurface of the 'stencilsheet should be kept me minimum since otherwise the sheet may adhere to the separating member so strongly during separation that the portion of the, sheet between the drum and the separating member may buckle or that the sheet may be unable to fall away from the separating member under the action of gravity following release of the sheet from the claniping fneans.
  • the separating member preferably comprises an elongate member arranged'to extend substatitially parallel to the axis of rotation of the drum.
  • this elongate member is a length of filamentary material, for example a metal or plastics filament, which, at least when brought up adjacent to the drum surface, extends more or less parallel to the druiii axis.
  • the elongate member may be a length of tape, preferably narrow tape, ora knife-edged member. Where a tape or filament. is involved,- it should be suitably tensioned to carry out; its function.
  • separating member employed in an apparatus embodying the invention is preferably supported by the positioning mechanism for pivotal movement about an axis substantially parallel to the axis of rotation of the rotary drum.
  • the exact timing of the commencement of reverse rotation of the drum relative to the bringing of the separating member into its operative position adjacent to the drum is not critical.
  • the separating member should however be in position by the time that the trailing edge of the sheet reaches the separating location in the course of the reverse rotation of the drum.
  • clamp-release means For automatic control of sheet release, there may be provided clamp-release means arranged to bring about release of the previously clamped end of a flexible sheet by the clamping means when, in the course of reverse rotation, the drum reaches the predetermined sheet-end release position.
  • the clamp-release means may for example be provided with a solenoid for controlling operation of the clamp-release means.
  • the clamp-release means may for example include a clamp control cam with which the solenoid is coupled to control the cam so that when brought by the action of the solenoid from a non-operational position into an operational position in the path of rotation of a cam follower which is mounted, movably relative to the drum, for rotation in synchrony with the drum and is controllingly coupled with the sheet clamping means, the cam moves the cam follower into a clamp-release disposition when, in the course of reverse rotation, the drum reaches the predetermined sheet-end release position.
  • a clamp control cam with which the solenoid is coupled to control the cam so that when brought by the action of the solenoid from a non-operational position into an operational position in the path of rotation of a cam follower which is mounted, movably relative to the drum, for rotation in synchrony with the drum and is controllingly coupled with the sheet clamping means, the cam moves the cam follower into a clamp-release disposition when, in the course of reverse rotation, the drum reaches the predetermined sheet-end release position.
  • the positioning mechanism arranged to bring the separating member into its operative position adjacent the drum so as to come between the circumferential surface thereof and the free end portion of a clamped sheet when the drum is rotated in reverse may be provided with a solenoid arranged to control movement of the positioning mechanism between its operative and non-operative dispositions.
  • Switch means may be provided to control energization of either solenoid in dependence upon the rotary position of the drum. 7
  • FIGS. 1, 2 and 3 are respective like schematic sectional views of rotary duplicating apparatus embodying FIG. 4 is an end view of part of the apparatus, and
  • FIG. is a fragmented perspective view of part of the apparatus.
  • the illustrated apparatus comprises a duplicator drum 1 arranged so that it can be rotated about its rotary axis both in a particular direction for the purposes of duplicating,-and in reverse.
  • the drum 1 is provided with stencilsheet clamping means comprising a fixed clamping jaw 2, which extends axially of the drum at a circumferential location thereon, and a cooperating movable clamping jaw 3 which also extends'axially of the drum.
  • the movable clamping jaw 3 is movable from a first position, for which the sheet clamping means are in an open condition allowing an end portion of a sheet to be inserted between the clamping jaws 2 and 3, and a second position for which the clamping means are in a closed condition in which the clamping jaws 2 and 3 will grip between them any such end portion inserted therebetween while the clamping means were in the open condition.
  • FIG. 1 One end portion of a stencil sheet 4 is shown in FIG. 1 gripped between the closed clamping jaws 2 and 3 while the rest of the sheet extends around the external surface of the drum. Most of the'stencil sheet extends adjacent to an inked surface portion 5 of the drum to which the sheet thus adheres on account of the tackiness of the ink.
  • the sheet 4 has a trailing edge portion 6, however, which is adjacent to a non-inked metal circumferential surface portion 7 of the drum 1.
  • the drum 1 rotates in the opposite direction to that indicated by the arrow A.
  • the drum is rotated in the direction of the arrow and a pair of parallel arms 8 (only one visible in FIGS. 1 to 3 and neither visible in FIG. 4) supporting a metal the invention at three stages in the operation thereof,
  • filament 9 extending parallel to the axis of the drum 1 is pivoted, from the position indicated in FIG. 1 remote from the drum, to the position indicated in FIG. 2 adjacent to the drum.
  • the filament 9 thus comes between the end portion 6 of the sheet 4 and the adjacent surface portion of the drum 1 as the drum is rotated in the arrowed direction. Consequently, the remaining part 10 of the sheet 4 is progressively lifted from the surface of the drum 1 as the drum rotates, as shown in FIG. 2.
  • the sheet clamping means Prior to arrival of the clamping jaws 2 and 3 at the separating location as the drum 1 continues to rotate, the sheet clamping means are opened. This allows the previously gripped end portion of the sheet 4 to fall away from between the clamping jaws 2 and 3 so that the sheet can be completely separated from the drum.
  • the operation of the clamping jaw 3 is controlled with the aid of a clamp control solenoid S, which when energized causes a clamp control cam 11 pivotable about an axis fixed to the apparatus (see FIG. 4) to be brought into an operational position in the path of rotation of a cam follower 12 which rotates in synchrony with the duplicator drum 1, this cam follower serving to control the clamping means.
  • a clamp control solenoid S which when energized causes a clamp control cam 11 pivotable about an axis fixed to the apparatus (see FIG. 4) to be brought into an operational position in the path of rotation of a cam follower 12 which rotates in synchrony with the duplicator drum 1, this cam follower serving to control the clamping means.
  • the cam follower 12 is cammed for part of each rotation of the drum so as to cause the clamping jaw 3 to be held apart from the clamping jaw' 2 for that part of the rotation.
  • Rotation of the drum is controlled with the aid of a microswitch 13 which is arranged to cooperate with a cam 14 that rotates in synchrony with the drum 1.
  • the microswitch 13 When cammed, the microswitch 13 is in an open condition in which, normally, drum rotation is prevented. Since, when the apparatus is in the ready-for-unloading condition illustrated in FIG. 1, the microswitch 13 is cammed open by the cam 14, to start rotation of the drum 1 the microswitch 13 must be overriden by a start button (not shown).
  • Bringing-up of the separating filament 9 supported between the arms 8 is controlledwith the aidof a microswitch 15 arranged to cooperate with a cam 16 which, like the cam-l2, also rotates in synchrony with the drum 1.
  • a microswitch 15 arranged to cooperate with a cam 16 which, like the cam-l2, also rotates in synchrony with the drum 1.
  • the microswitch 15 brings about energization of a solenoid S which, when energized, causes the separating filament 9 to be moved to and held at the separating location adjacent to the surface. of the drum 1 for the duration of the energization.
  • Camming of the microswitch 15 into its open condition by the cam 16 is also arranged to bring aboutenergization of the clamp control solenoid S,, so that while the microswitch 15 remains cammed in its closed condition the clamp control cam llis held in the path of rotation of the cam follower 12 for operating the clamping means.
  • the illustrated apparatus operates as follows: Initially the apparatus is in the ready-for-unloading condition illustrated in FIG. 1, in which the microswitch 13 is held open by the cam 14, thereby preventing rotation of the drum 1. To start rotation, the abovementioned start button is pressed, thereby overriding the microswitch 13. With the pressing of the start button the drum 1 begins to rotate in the direction of the arrow A. After the drum has rotated through a small angle, say 3 or so, the cam 14 has rotated sufficiently to allow the mirwitch 13 to return to its closed condition; once the microswitch 13 is in its closed condition, rotation of the drum will thus continue whether or not the start button remains depressed.
  • the microswitch is cammed by the cam 16 into its closed condition, thereby energizing the clamp control solenoid S and the solenoid S controlling the position of the separating filament 9. Accordingly, the clamp control cam 11 is brought into its operational position in the path of rotation of the cam follower 12 for controlling the clamping means, and the supporting arms 8 are pivoted to a position in which the separating filament 9 is at the separating location adjacent to the drum surface.
  • FIG. 3 illustrates the apparatus when the clamping means have been opened to allow release of the previously gripped edge portion of the sheet 4.
  • the control of drum rotation by the microswitch 13 may be effected by employing the microswitch to control an electromagnetic clutch (not shown) between drum gearing and drive means for the drum.
  • FIG. 4 Clamp-release means for effecting release of the sheet clamping means are illustrated in FIG. 4. From FIG. 4, it can be seen that the position of the clamping jaw 3, which is mounted on the drum 1 so as to be pivotable about an axis parallel to the rotary axis of the drum, is controlled by an abutting cam actuating lever 17 also mounted on the drum so as to be pivotable about an axis parallel to the rotary axis of the drum. At an end portion thereof remote from the clamping jaw 3 the above-mentioned cam folllower 12 is pivotally mounted on the clamp actuating lever 17.
  • the cam 11 with which the cam follower 12 is adapted to cooperate is supported on a cam support arm 18 which is pivotally mounted about an axis parallel to the axis of the drum but fast with respect to the apparatus as a whole.
  • the position of the cam 11 is controlled by a cam actuating lever 19 which is pivotally connected at one end thereof to the cam 11.
  • the other end of the cam actuating lever 19 is pivotally connected to a sole noid arm 20 whose position is controlled in dependence upon energization of the solenoid 8,.
  • the-cam l is moved from a non-operational position away from the path of rotation of the cam follower 12 into an operational position in that path of rotation.
  • the solenoid 8 remains energized, the cam follower 12 will be cammed for part of every revolution of the drum into a clamp-release disposition in which the clamp actuating lever l7 is caused to hold the clamping jaw 3 apart from the clamping jaw 2 fixed relative to the drum.
  • the solenoid S is unenergized
  • FIG. 5 The positioning mechanism for bringing the separating filament 9 into its operative position adjacent to the surface of the drum 1 is illustrated in FIG. 5.
  • the parallel arms 8 between which the separating filament 9 is supported in tension extend from a common support shaft 21 which is aligned along an axis parallel to the axis of rotation of the drum 1.
  • An actuating arm 22 extending from the support shaft 21 is coupled to the solenoid S sothat, when energized, the solenoid pulls the actuating arm downwards as seen in FIG. 5, thereby causing the support shaft 21 to be rotated about its longitudinal axis by a certain amount.
  • said-apparatus including:
  • reversible drive means coupled to said drum and changeable between a forward-drive condition, rotating said drum in the direction opposite to said given direction, and in a reverse-drive unloading condition rotating said drum in said given direction; separating member for removing the sheet from said circumferential surface; positioning mechanism supporting said separating member, movable between a non-operative disposition, for holding the separating member away from said drum, and an operative position for interposing said separating member between said circumferential surface and said sheet when said drum means are in said unloading condition; and clamp-release means, defining a sheet-end release position for the drum, arranged to de-actuate said sheet-clamping means when said drive means rotating the drum in said given direction bring the drum into said sheet-end release position.
  • said separating member comprises an elongate member held extending substantially parallel to the axis of rotation of said drum.
  • clamp-release means are provided with a solenoid ar- 8 ranged to control operation of said clamp-release means.
  • a clamp control cam movable between an operational position and a non-operational position, said solenoid being controllingly coupled with said cam for bringing about movement of said cam between said operational and non-operational positions;
  • cam follower mounted, movably relative to said drum, for rotation in synchrony with said drum along a given path of rotation in which said operational position is located, said cam follower being controllingly coupled with said sheet-clamping means for de-actuating said sheetclamping means when said cam follower is moved into a clamprelease disposition; said cam co-operating with said cam follower, when with said cam in said operational position said drum is rotated in said given direction into said sheet-end release position, to cam said cam follower into'said clamp-release disposition.
  • Apparatus as claimed in claim 8 including switch means arranged for controlling energization of said solenoid in dependence upon'the rotary position of said drum.
  • Apparatus as claimed in claim 9, including switch means arranged for controlling energization of said solenoid in dependence upon the rotary position of said drum.
  • Apparatus as claimed in claim 1 said apparatus constituting a rotary printing machine in which said drum is a support drum for supporting a flexible sheetform printing plate.

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  • Feeding Of Articles By Means Other Than Belts Or Rollers (AREA)
  • Handling Of Cut Paper (AREA)
US00404686A 1972-10-09 1973-10-09 Removal of flexible sheets from rotary drums Expired - Lifetime US3839958A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB4650572A GB1444913A (en) 1972-10-09 1972-10-09 Removal of flexible sheets from rotary drums

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US3839958A true US3839958A (en) 1974-10-08

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US (1) US3839958A (enrdf_load_stackoverflow)
BE (1) BE805737A (enrdf_load_stackoverflow)
CA (1) CA1009672A (enrdf_load_stackoverflow)
DE (1) DE2350671A1 (enrdf_load_stackoverflow)
FR (1) FR2202474A5 (enrdf_load_stackoverflow)
GB (1) GB1444913A (enrdf_load_stackoverflow)
IT (1) IT1004603B (enrdf_load_stackoverflow)
LU (1) LU68570A1 (enrdf_load_stackoverflow)
NL (1) NL7313849A (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4557474A (en) * 1984-06-21 1985-12-10 The Mead Corporation Duplex document copying machines
US5461980A (en) * 1992-07-31 1995-10-31 Komori Corporation Plate mounting apparatus for printing press
US20120067995A1 (en) * 2010-09-22 2012-03-22 E. I. Du Pont De Nemours And Company Method and apparatus for tensioning a printing form
US8459182B2 (en) 2010-09-17 2013-06-11 E I Du Pont De Nemours And Company Method and apparatus for securing printing forms on a mountable surface

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1596995A (en) * 1977-06-14 1981-09-03 Ibm Electroplating chromium and its alloys
GB1502522A (en) * 1976-11-25 1978-03-01 Gestetner Ltd Stencil ejector on a stencil duplicator
US4386771A (en) * 1981-05-08 1983-06-07 Xerox Corporation Method of removing a sheet from a drum

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2758539A (en) * 1951-08-08 1956-08-14 Ritzerfeld Wilhelm Sheet strippers for rotary duplicators
US2821910A (en) * 1954-05-10 1958-02-04 Dick Co Ab Master ejecting mechanism for duplicators
US3062135A (en) * 1960-06-13 1962-11-06 Eastman Kodak Co Photographic copying apparatus stripping mechanism
US3181459A (en) * 1962-08-13 1965-05-04 Ritzerfeld Wilhelm Stripper arrangement for a printing machine

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2758539A (en) * 1951-08-08 1956-08-14 Ritzerfeld Wilhelm Sheet strippers for rotary duplicators
US2821910A (en) * 1954-05-10 1958-02-04 Dick Co Ab Master ejecting mechanism for duplicators
US3062135A (en) * 1960-06-13 1962-11-06 Eastman Kodak Co Photographic copying apparatus stripping mechanism
US3181459A (en) * 1962-08-13 1965-05-04 Ritzerfeld Wilhelm Stripper arrangement for a printing machine

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4557474A (en) * 1984-06-21 1985-12-10 The Mead Corporation Duplex document copying machines
US5461980A (en) * 1992-07-31 1995-10-31 Komori Corporation Plate mounting apparatus for printing press
US8459182B2 (en) 2010-09-17 2013-06-11 E I Du Pont De Nemours And Company Method and apparatus for securing printing forms on a mountable surface
US20120067995A1 (en) * 2010-09-22 2012-03-22 E. I. Du Pont De Nemours And Company Method and apparatus for tensioning a printing form
US8397636B2 (en) * 2010-09-22 2013-03-19 E I Du Pont De Nemours And Company Method and apparatus for tensioning a printing form

Also Published As

Publication number Publication date
GB1444913A (en) 1976-08-04
CA1009672A (en) 1977-05-03
IT1004603B (it) 1976-07-20
LU68570A1 (enrdf_load_stackoverflow) 1973-12-14
DE2350671A1 (de) 1974-04-25
BE805737A (fr) 1974-02-01
FR2202474A5 (enrdf_load_stackoverflow) 1974-05-03
NL7313849A (enrdf_load_stackoverflow) 1974-04-11

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