GB2112359A

GB2112359A - Spiked grippers transporting sheets through a platen press

Info

Publication number: GB2112359A
Application number: GB08139021A
Authority: GB
Inventors: Robert William Jardine; Kenneth Hamilton Mcmurray
Original assignee: Simon Container Machinery Ltd
Current assignee: Simon Container Machinery Ltd
Priority date: 1981-12-30
Filing date: 1981-12-30
Publication date: 1983-07-20

Abstract

Gripper bars (18) for carrying sheets through a platen press comprise spiked gripper bars (18) upon which a sheet is impaled, and a plurality of spring-loaded sheet- retaining plates (22). The plates (22) can be moved away from the spikes (20) by a pawl and cam mechanism (23, 24) but returned under spring pressure to retain the sheet on the spikes until positively removed therefrom by means at the delivery station. In an alternative arrangement (Fig. 5), the sheets are retained by swinging arms (40) moving around a vertical axis. Plates can be arranged at the sheet delivery station to grip the sheet edge on the spiked gripper bars whilst the remainder of the sheet is removed therefrom. <IMAGE>

Description

SPECIFICATION A sheet transport system for a platen press This invention concerns a sheet transport system for a platen press of the kind used for cutting, creasing or embossing individual sheets of card or cardboard passed therethrough, where the sheets are carried through the press successively by gripper bars spaced around a pair of parallel endless chains.

Many types of transport system have been proposed for gripping the sheets as they pass through the press, some such mechanisms consisting of pairs of fingers on the gripper bars, which grip the edge of a sheet and cause it to advance. Other types of gripper consist of leaf springs attached to the gripper bars.

When transporting sheets of corrugated board it is important to avoid damaging the gripped edge region of the board, especially in cases where it is to form part of a finished box. To overcome this problem a system was devised wherein each gripper bar carries a plurality of pins upon which a sheet to be transported is impaled at the sheet feed station. Whilst the pins maintain the board in a fixed registered position, there is the disadvantage that heavy board can fall off the pins during transport, particularly if the board is warped, or the pins can become loose in their holes when pulling heavy sheets. The untimely removal of sheets from the transport system can cause considerable damage to the machine when operating at normal working speeds.

An object of the present invention is to provide a sheet transport system for a platen press incorporating pinned gripper bars, but avoiding the risk of premature removal of the sheets.

According to the present invention there is provided a sheet transport system for a platen press comprising a pair of driven parallel endless chains carrying between them a series of equidistant gripper bars adapted to advance sheets successively through the press from a feed station to a delivery station as the chains are advanced, each gripper bar having thereon a plurality of spikes upon which a sheet to be transported is imparted and, for at least some of said spikes, sheet retaining members which prevent removal of the impaled sheet, there being means at the feed station for temporarily withdrawing said retaining members to permit a sheet to be impaled, and means at the delivery station for permitting removal of at least part of the sheet from the gripper bar.

The invention will be described further, by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a schematic side elevation of a platen press incorporating a sheet transport system constructed in accordance with the invention; Fig. 2 is an enlarged detailed, part-sectional view of part of the transport system adjacent the feed station of the press; Fig. 3 is an enlarged detailed, part-sectional view of another part of the transport system adjacent the delivery station of the press; Figs. 4 is an enlarged, part-sectional view of a still further part of the transport system; and Fig. 5 is a part-sectional plan view of an alternative form of part of a transport system constructed in accordance with the invention.

Referring now to the drawings, the platen press comprises a pair of driven parallel endless chains one of which is illustrated at 10, which by passing around driven chains wheels 11 and 12 and guides for sprockets 1 3 serves, as will be described, to transport sheets successively between the platens 14 of the press and onwards through a stripping mechanism 15, to a delivery station where the sheets are stacked on a descending table 1 6. Upstream of the press the sheets are supplied by a feeder 1 7 which advances them one at a time towards the moving chains.

Spaced equidistant around the chains is a series of gripper bars 1 8 each of which carries along its length a plurality of leaves 19 each carrying a gripper spike 20 as can be seen from Fig. 2. Mounted for rotation on each gripper bar 1 8 is a spindle 21 which carries for rotation therethrough a series of sheet retaining plates 22, one below each leaf 19, and having apertures through which the pins 20 pass when the spindle 21 rotates in an anti-clockwise direction as viewed in Fig. 2 to elevate the plates 22 to the level of the spikes. Mounted on one end of the spindle 21 is a pawl 23, and the spindle with its associated plates 22 and pawl 23 is spring loaded to rotate in an anti-clockwise direction as viewed in Fig. 2. The chain wheel 11 carries a cam 24 close to the periphery which as can be seen in Fig.

2 engages the pawl 23 to part the plates 22 from the spikes 20 thus to enable a sheet to become impaled on the spikes.

Adjacent the feed station on the press is a stop member 25 known as a front lay and a pusher plate 26 which together with the member 25 can be raised and lowered in sequence with the operation of the press as will be described. It will be seen from Fig. 2 that when the gripper bar has advanced with the chains in the direction of transport, the cam 24 released the pawl 23 to enable the plates 22 to close on the spikes 20 thus preventing removal of the impaled sheet.

Referring now to Fig. 3 there is illustrated a device for removing at least a part of the sheet from the gripper bar for stacking on the table 1 6.

The device comprises a vertically movable pusher plate 27 above the level of transport of the sheets, and another vertically movable pusher plate 28 positioned below the sheets and slightly ahead of the pusher plate 27. It is common practice to retain a so-called grip edge (indicated in Fig. 3 by the letter a) on the gripper bar and to cause the remainder of the sheet, (indicated at b) to be severed therefrom. During the cutting process the platens 14 perforate the sheet as indicated at c, to permit separation. In some cases, however, it is desirable to remove the whole of the sheet from the gripper bar, and in this case the pusher plate 28 is omitted, and the pusher plate 27 removes the sheet by forcing it off the pins 20 against the action of the springs which normally hold the plates 22 against the underside of the sheet.The resilience of the springs is selected accordingly to permit the sheet to be removed without damaging the gripper mechanism.

Referring now to Fig. 4, assuming that the grip edge illustrated at a in Fig. 3 has been retained on the gripper spikes 20 then it is necessary for this to be removed before the gripper bar returns to the feed station to pick up a further sheet. For this purpose, downstream of the first idler sprocket 13 there is provided below the path of travel of the gripper bars a series of fingers 29 disposed in spaced relationship along a rotatable spindle 30 journalled in the machine frame. Above the path of the gripper bars there is a similar series of fingers 31 disposed along a similar rotatable spindle 32. It will be appreciated that the fingers 29 and 31 are arranged in vertical planes which pass between the leaves 1 9 and plates 22.Thus, as illustrated in Fig. 3 by simultaneous clockwise and anti-clockwise rotation respectively of the spindles 30 and 32, the corresponding fingers 29 and 31 move together to grip the remaining grip edge a of the sheet thus to remove same from the gripper pins 20. After the pins and gripper bar have passed, the grip edge is released from the fingers by reverse movement of the spindles 30 and 32, and is deposited on to a transverse conveyor 33 passing therebeneath which carries the discarded grip edges to a collection point outside the press.

Referring now to Fig. 5, in an alternative embodiment, the downwardly moving plates 22 as illustrated in Fig. 2 are replaced by winging arms 40 which rotate about a vertical axis 41 thus to swing in a horizontal plane with respect to the pins 20. This swinging movement is effected by a rod 43 which extends along the gripper bar 1 8 and is operated by a fixed cam (not shown) on the machine frame thus to remove the swinging arms 40 from the pins at the feed and delivery stations to permit attachment and removal respectively of a sheet. Preferably, the rod 43 is spring loaded normally to cause the arms to engage the underside of the sheet to prevent its removal from the pins until the sheet arrives at the delivery station.

Claims (Filed on 21/12/82) 1. A sheet transport system for a platen press comprising a pair of driven parallel endless chains carrying between them a series of equidistant gripper bars adapted to advance sheets successively through the press from a feed station to a delivery station as the chains are advanced, each gripper bar having thereon a plurality of spikes upon which a sheet to be transported is impaled, and, for at least some of said spikes, sheet retaining members which prevent removal of the impaled sheet, there being means at the feed station for temporarily withdrawing said retaining members to permit a sheet to be impaled, and means at the delivery station for permitting removal of at least a part of the sheet from the gripper bar.

2. A system according to Claim 1, wherein each said retaining member comprises a pivotable member adapted to bear against said impaled sheet, said withdrawing means acting to cause said member to pivot away from the associated spikes.

3. A system according to Claim 2, wherein said retaining members are mounted for pivotal movement about a common horizontal axis.

4. A system according to Claim 2, wherein said retaining members are individually mounted for pivotal movement relative to the gripper bar about a plurality of vertical axes.

5. A system according to any preceding claim, wherein said retaining members are biased against the pressure of a spring such as to prevent removal of the impaled sheet, the means at the delivery station for permitting removal of at least part of the sheet from the gripper bar acting against said spring to cause the retaining members to pivot away from their associated spikes.

6. A system according to Claim 1, wherein said means at the delivery station for permitting removal of at least part of the sheet from the gripper bar comprises a pair of pusher plates disposed respectively above and below the impaled sheet and acting together to retain a grip edge on its associated gripper bar spikes whilst removing the remainder of a sheet therefrom.

7. A system according to Claim 6, including means downstream of the delivery station with respect to the direction of travel of the chains, and movable to release said grip edge from its associated gripper bar.

8. A system according to Claim 6, wherein said release means comprises at least one pair of cooperating fingers simuitaneously rotatable to grip and subsequently release said grip edge, there being means disposed below said fingers to carry the released grip edges away for collection.

9. A system according to any one of Claims 1 to 3, including a pawl rotatable on said pivotable axis with said retaining members and actuated, as the associated gripper bars passes through the feed station, by a cam disposed at said feed station.

10. A system according to Claim 1 or Claim 4, wherein said retaining members comprise a plurality of swinging arms which are rotated about said vertical axes by a common member extending along the gripper bar and operated by a fixed cam.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. this case the pusher plate 28 is omitted, and the pusher plate 27 removes the sheet by forcing it off the pins 20 against the action of the springs which normally hold the plates 22 against the underside of the sheet. The resilience of the springs is selected accordingly to permit the sheet to be removed without damaging the gripper mechanism. Referring now to Fig. 4, assuming that the grip edge illustrated at a in Fig. 3 has been retained on the gripper spikes 20 then it is necessary for this to be removed before the gripper bar returns to the feed station to pick up a further sheet. For this purpose, downstream of the first idler sprocket 13 there is provided below the path of travel of the gripper bars a series of fingers 29 disposed in spaced relationship along a rotatable spindle 30 journalled in the machine frame. Above the path of the gripper bars there is a similar series of fingers 31 disposed along a similar rotatable spindle 32. It will be appreciated that the fingers 29 and 31 are arranged in vertical planes which pass between the leaves 1 9 and plates 22.Thus, as illustrated in Fig. 3 by simultaneous clockwise and anti-clockwise rotation respectively of the spindles 30 and 32, the corresponding fingers 29 and 31 move together to grip the remaining grip edge a of the sheet thus to remove same from the gripper pins 20. After the pins and gripper bar have passed, the grip edge is released from the fingers by reverse movement of the spindles 30 and 32, and is deposited on to a transverse conveyor 33 passing therebeneath which carries the discarded grip edges to a collection point outside the press. Referring now to Fig. 5, in an alternative embodiment, the downwardly moving plates 22 as illustrated in Fig. 2 are replaced by winging arms 40 which rotate about a vertical axis 41 thus to swing in a horizontal plane with respect to the pins 20. This swinging movement is effected by a rod 43 which extends along the gripper bar 1 8 and is operated by a fixed cam (not shown) on the machine frame thus to remove the swinging arms 40 from the pins at the feed and delivery stations to permit attachment and removal respectively of a sheet. Preferably, the rod 43 is spring loaded normally to cause the arms to engage the underside of the sheet to prevent its removal from the pins until the sheet arrives at the delivery station. Claims (Filed on 21/12/82)

1. A sheet transport system for a platen press comprising a pair of driven parallel endless chains carrying between them a series of equidistant gripper bars adapted to advance sheets successively through the press from a feed station to a delivery station as the chains are advanced, each gripper bar having thereon a plurality of spikes upon which a sheet to be transported is impaled, and, for at least some of said spikes, sheet retaining members which prevent removal of the impaled sheet, there being means at the feed station for temporarily withdrawing said retaining members to permit a sheet to be impaled, and means at the delivery station for permitting removal of at least a part of the sheet from the gripper bar.

11. A sheet transport system for a platen press,

substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 4 or Figure 5 of the accompanying drawings.