CN101516751A

CN101516751A - Auxiliary drive for conveying sheets on the feed table of a die-cutting press

Info

Publication number: CN101516751A
Application number: CNA2007800340302A
Authority: CN
Inventors: 让-克劳德·丽贝艾德
Original assignee: Bobst SA
Current assignee: Bobst Mex SA
Priority date: 2006-07-17
Filing date: 2007-07-16
Publication date: 2009-08-26
Also published as: BRPI0714836A2; WO2008009402A1; KR20090028837A; EP2041009A1; US20090243208A1; JP2009543701A

Abstract

The present invention provides an auxiliary drive for a machine that processes plate elements of the type comprising a feed table provided with at least one lower drive belt (11) for conveying a sheet (3) of plate elements. The drive comprises a frame intended to be positioned above the feed table of the processing machine. According to the invention, the frame supports-at least one upper drive belt(15) capable of co-operating with the lower drive belt(s)(11) for conveying said sheet (3) of plate elements by exerting pressure and driving force on the upper surface of the sheet (3), and-a drive mechanism of the upper belt(s)(15), capable of driving the upper drive belt(s)synchronously with the lower drive belt(s)(11). The invention further relates to a processing machine for plate elements of the type comprising a feed table provided with at least one lower drive belt (11) for conveying a sheet (3) of plate elements comprising said auxiliary drive.

Description

Auxiliary driving device for conveying sheets on feeding table of cutting press

The invention relates to an auxiliary drive for the transport of sheets or boards arranged in layers on the feed table of a cutting press.

In the hitherto known cutting presses, an example of which is shown in figure 1, the sheet to be processed is taken from the top of a stack of sheets 1, arranged in layers 3 and then transferred to a feed table before being introduced into the gripper 4 of the transport element 5 of the cutting and pressing station. Thus, EP1170228 describes an example of a single sheet feeder in which sheets are arranged in layers; and EP0680906 describes an example of a transport of a slitting and pressing station using a gripper bar.

Fig. 2 and 3 show in more detail the arrangement of the sheets in layers and the means for feeding the layers. A stack of sheets 1 is fed with the layer of sheets 3 by means of the suction unit 2, the top of the stack of sheets 1 being maintained at a constant height due to the elevation of the stack of sheets support plate 6 driven by the motor 7. The sheet 8 at the top of the stack 1 is clamped at the rear and then pushed forward by the suction unit 2 to form the layer 3, sliding the front of the sheet 8 under the previous sheet 10.

Obviously, the sheets of layer 3 are accurately positioned in the longitudinal and transverse directions by positioning means (not shown). EP0669274, EP1044908 and EP1151833 describe examples of positioning means for forming the sheets in the layer 3. As described in these documents, this positioning operation is performed on one of the ends of the supply table and can be achieved by: by means of front and side stops, the edge of the sheet introduced into the slitting station is made to rest against these stops, or a more complex system is used which does not require stopping of the sheet.

The feed table known hitherto usually comprises an inclined plate 12, which may be, for example, a metal or wooden plate, which serves as a support for the upper run of at least one drive belt 11. If there are several belts 11, these belts are arranged side by side over the width of the ramp surface 12, so that this ramp surface supports the upper run of each belt 11.

In order to transfer the sheet of layer 3 onto the supply table 12, at least one upper auxiliary presser 13 is often used. The upper auxiliary presser 13 is mounted on the frame so as to be positionally adjustable on the upper section of the or each belt 11. These auxiliary pressure elements 13 are most often designed in the following form: slides, rollers or small belt conveyors, whose pressure on the layer to be conveyed can sometimes be adjusted. An example of an upper auxiliary presser 13 is described in EP 0684201. When positioned with the contacts resting on the stop, rotating brushes are often used, said brushes being positioned such that the bristles thereof are set back when the leading edge of the first sheet in the layer comes into contact with the stop, thus avoiding accidental damage to the edges of the sheets by the feeding action of the conveyor.

In the known device, the auxiliary presser 13 has only the function of pressing against the layer 3, so that it lies flat against the upper run of the or each belt 11.

The decisive parameter for the driving force of the layer 3 is the friction force. Furthermore, the upper section of the or each sheet conveyor belt 11 projects only slightly above the surface of the sloping plate 12 to ensure proper conveyance of the low-weight paper.

If the sheet is not made of flexible material, such as low basis weight paper or cardboard, but also has a very slippery surface, the contact between the layer 3 and the upper section of the conveyor belt 11 will no longer be sufficient to ensure an accurate and uniform speed transfer of the layer 3, a device comprising two conveyor belts 11 being shown in fig. 5. This may occur in particular with corrugated cardboard that is glued together. It is therefore necessary to greatly increase the pressure Fv of the upper auxiliary presser 13, which in some cases may lead to a partial flattening of the corrugated cardboard, which is unacceptable nowadays.

The object of the present invention is to overcome the aforementioned drawbacks so that the transport of the sheet material is carried out correctly, without damaging it, whatever the material from which it is made.

To this end, the invention relates to an auxiliary drive of a machine for processing sheets according to claim 1 and to a cutting press for sheets according to claim 7. Claims 2 to 6 define preferred embodiments of the invention.

The invention will be better understood with reference to the preferred embodiments, provided by way of non-limiting example, and illustrated in the accompanying drawings. Wherein,

FIG. 1 is a schematic view of a conventional cutting press;

FIG. 2 is a schematic diagram showing different stations of a conventional cutting press;

figures 3 and 4 show a schematic view of a prior art apparatus in which sheets are arranged in layers and the layers are fed;

FIG. 5 is a schematic illustration of the problem posed by the high-volume sheets of the prior art device in some cases;

figures 6, 7 and 8 show different schematic views of the device according to the invention; and

fig. 9 shows a view of an embodiment of the transmission mechanism of the device according to the invention.

From the perspective of terminology, to avoid any confusion in the following description, the terms "upstream" and "downstream" will be defined relative to the direction of displacement of the layered sheet. The layer moves from upstream to downstream along the principal axis of the machine. The terms "longitudinal" and "transverse" will also be defined with respect to the main axis of the machine, the expression "sheet" being considered equivalent to the expression "paper or cardboard", so as to avoid complicating the description by referring to constructional details not directly related to the invention and well known to a person skilled in the art.

The present invention thus relates to a sheet processing machine of the type comprising a feed table equipped with at least one lower conveyor belt 11 to convey a layer 3 of sheets, such as the cutting press shown in figure 1 and described above. When these machines are equipped with a hybrid positioning device that does not require sheet stopping, the range of output speeds can be: 8000 tablets per hour to 12000 tablets per hour.

Fig. 6 shows an auxiliary drive according to the invention. According to the invention, the apparatus comprises a frame intended to be arranged on top of a supply table of a processing machine. According to the invention, the frame supports at least one upper conveyor belt 15. If desired in the embodiment of the invention shown in fig. 6, it may support two upper drive belts. These upper belts 15 are driven synchronously with the lower belts 11 by means of shafts 16.

In the embodiment of the invention shown in fig. 6, the device comprises two movable carriages slidable on two guide bars 26. Advantageously, as shown in fig. 6, one of the carriages is a normalized movable carriage 17 which allows the or each upper belt 15 to be shifted so that it does not rest on top of the layer 3, and it pushes only the latter until the sheet 14 furthest downstream of the layer 3 is taken up by the positioning means and then by the gripper bars 4 of the transport element 5. Therefore, the normalized movable carriage 17 can optimize conveyance of the layer 3 regardless of the manner in which the sheet is formed. In the embodiment shown in fig. 6, the normalized movable carriage 17 is the carriage located most downstream.

As shown in fig. 7, the movable carriage comprises at least one transmission pulley 21 that can form an endless belt 15, and at least one roller 29 pushed by an elastic member 22 to ensure the tension of the belt 15.

Alternatively, the auxiliary device according to the invention can be raised by rotating the frame about an axis 25 located near one end thereof. In fig. 6 the shaft 25 is located close to the downstream end of the frame, but it is also fully feasible to implement the invention by arranging the shaft close to the upstream end of the frame. When the device is raised, the operator of the treatment machine can easily remove any sheets that are not properly divided in the layer 3 or that may not be evenly spaced.

The device preferably comprises one or more pressure pulleys 20 which exert a pressure on the belt 15 and which are movable in a direction perpendicular to the surface of the belt 15 so as to be able to adapt to the thickness of the layer 3 and to maximize the surface area of the layer 3 subjected to the pressure and the driving force of the belt 15.

The side plates 30 arranged on the movable carriage shown in fig. 8 support all the different transmission and pressure pulleys (20, 21, 31, 32). Thus, the combination of the set of pulleys, the side plates 30 and the belt 15 constitutes a bogie.

The device preferably comprises means 23 for adjusting the pressure exerted by the upper belt 15 on the layer 3. These means 23 for adjusting the pressure reduce the weight of the device or, on the contrary, in addition to the weight of the device itself, even press tightly on the layer 3. In the embodiment shown in fig. 8, the pressure-adjusting means 23 consist of a pneumatic jack, the pressure of which can be adjusted. Thus, in this embodiment of the invention, the bogie is movable. The operating position of the bogie is defined by two arms 28, one of which is articulated by an extension 27 of the movable carriage 17 and the other of which is articulated on a shaft, about which the bogie assembly can also be rotated so as to press against the surface of the layer 3 in the best possible manner.

The drive mechanism for the upper drive belt 15 may take different forms, including in particular the form of a mechanical connection of the drive shaft 19 of the lower drive belt 11 with the drive shaft 16 of the upper drive belt 15. Fig. 9 shows an embodiment in which two friction wheels 24 realize such a mechanical connection.

The upper conveyor belt 15 of the device according to the invention exerts a driving force on top of the layer 3 to ensure the correct conveyance of the latter, whatever the material of the sheet, and without applying excessive pressure. It is thus possible to use a small number of upper belts 15 and even to reduce the number of lower belts 11 on the feed table of the cutting press.

Furthermore, the device according to the invention allows to identify and solve other technical problems. In the systems for conveying a layer of sheets at the supply station of existing machines, it is noted that the speed increases slightly during the conveyance of the sheets and that these sheets have a speed difference, which depends on the thickness of the layer and on the number of laminations. This is due to the effect of the side rim effect (effect of a side rim) of the pulleys that guide the sheets on the supply table. The web is thus slightly accelerated because it slides under and at the end of the layer 3 so that it is fed at a slightly faster speed than the lower belt 11. Furthermore, the speed difference between the layer 3 and the belt 11 depends on the number of sheets stacked within the layer thickness, and therefore the speed difference between the two varies between the first sheet in the layer and the economical speed.

The device according to the invention, thanks to the synchronous drive of the upper belt 15 with the lower belt 11, ensures a more precise transport than the systems of the prior art. In this way, the sheets are easily manipulated by the positioning device, so as to be able to better assess the position of each sheet within the layer 3 and the moment when the positioning device needs to take them out.

This problem does not constitute a prior problem to the solution proposed by the present invention, but the solution of this problem constitutes an additional undeniable advantage of the device according to the present invention compared to the existing devices.

Claims

1. An auxiliary drive of a sheet processing machine of the type comprising a feed table provided with at least one lower conveyor belt (11) for conveying a layer (3) of sheets, said device comprising a frame intended to be arranged above said feed table of said processing machine, characterized in that said frame supports:

-at least an upper conveyor belt (15) designed to cooperate with the lower conveyor belt (11) conveying the layer (3) of sheets by exerting pressure and driving force on the upper surface of the layer (3); and

-a drive mechanism of the upper conveyor belt (15), said mechanism being designed to drive the upper conveyor belt (15) synchronously with the lower conveyor belt (11).

2. An auxiliary drive as claimed in claim 1, characterized in that said means comprise a movable carriage (17) for arranging the or each upper belt (15) in a predetermined smooth manner.

3. Auxiliary drive as claimed in claim 1 or 2, characterized in that said means comprise a transmission and pressure pulley (20) movable in a direction perpendicular to the surface of the or each upper drive belt (15).

4. Auxiliary drive as claimed in any one of the foregoing claims, characterized in that said means comprise means for adjusting the pressure exerted by said upper belt (15) on said layer (3).

5. An auxiliary drive as claimed in claim 4, wherein said pressure adjustment means comprises a pneumatic jack.

6. Auxiliary drive as claimed in any of the foregoing claims, characterized in that the device is raisable by rotating the frame about an axis (25).

7. A sheet processing machine of the type comprising a supply station provided with at least one lower conveyor belt (11) for conveying a layer (3) of sheets, characterized in that it comprises an auxiliary drive according to any one of the preceding claims.