Apparatuses of the type concerned in the invention are used for stacking sheet substacks at least one sheet thick into higher stacks. From the prior art are known embodiments utilizing a carrier means similar to a con- veyor band as an intermediate support member at a stacking station. These conventional arrangements are hampered by a number of drawbacks including, among others, an inferior resistance of the material used in their intermediate support member to pointed/edged mechanical stress, which tends to cause tearing and cutting of the support means surface. Moreover, the conveyor material has in certain situation been able to mar the sheet material being stacked.

It is an object of the present invention to provide an apparatus capable of overcoming the disadvantages of the above-described prior-art embodiments.

The embodiment of the invention is characterized by what is stated in the appended claims.

An apparatus according to the invention offers a number of significant benefits. The structure of the inter- mediate support member used in the apparatus provides an extremely durable construction. The multilayer structure of the intermediate support member has a very good wear resistance. It is also resistant against cutting. Its soft outer layers are incapable of marring the sheets being stacked. Furthermore, its the felt-like surface texture complies to the small surface irregularities of the stacked sheets. Moreover, the apparatus is capable of making extremely neat stacks. The stack edges become straight as the intermediate support member can push the

transferred stacks of sheets very reliably against a back gage.

In the following the invention will be examined in greater detail with reference to the appended drawings, in which Figure 1 shows an apparatus according to the invention in a side view; Figure 2 shows an apparatus according to the invention in an end view; Figure 3 shows an apparatus according to the invention in a top view; and Figure 4 shows the structure of the intermediate support member used in the apparatus according to the invention schematically in sectional view.

Referring to the diagrams, the apparatus according to the invention shown therein comprises a framework 10 having a vertically movable platform 1 adapted thereto. The appa- ratus includes an intermediate support member 2 adapted to be movable into a position above the stacking platform 1 or above a stack of at least one sheet placed on said platform. The width of the intermediate support member 2 is advantageously made essentially equal to the width of the stacking platform 1. The next sheet or substack of sheets is brought on the intermediate support member 2 by means of, e. g., a pusher 4. The function of the inter- mediate support member is to make the transfer of sheets onto the underlying stack of sheets easier and to protect the substacks of sheets from marring each other. When the intermediate support member 2 is removed from between the stacked sheets, the sheets are allowed to rest on each other simultaneously as they are pushed at least by their

one edges against a back gage 3,4. The pusher 4 can act as a back gage during the retraction of the intermediate support member. The apparatus also includes means 5,6, 7,8 for moving the intermediate support member to above the stacking platform 2 and retracting the same from between the sheets. The intermediate support member 2 is connected by its one end to a support roller element 5, whose driven rotation by a drive means 6 forces the intermediate support member 2 to retract in a winding manner from the stacking area of the sheets. The appara- tus further includes guides 7 along which the movable intermediate support member is adapted to run. The guides serve to support carriages 8 to which the intermediate support member 2 is connected, e. g., by its edges.

The sheets or sheet substacks to be stacked are fed from the direction of arrow 9 marked in Fig. 2 by means of the pusher 4 onto the stacking platform 1or an intermediate support member 2 driven over the stack of sheets already stacked on the platform. When the new substack of sheets is fully pushed home in the stacking station, the inter- mediate support member 2 is removed from the gap remain- ing between the stacked sheets by actuating the roller element 5 to wind the intermediate support member away via the slot between the pusher 4 and the back gage 3.

Then, the upper part of the lower substack is supported by the back gage 3, while at least the lower part of the upper substack is supported by the pusher 4 which is located in essentially the same plane with the back gage.

Next, the platform 1 is lowered and the intermediate support member 2 is driven above the sheet stack resting in the stacking area, whereby a new sheet substack can be transferred onto the intermediate support member.

The intermediate support member 2 is made from a multi- layer material having at least one layer 2m of a material having a substantially high tear resistance. Furthermore,

at least one surface layer 2s of the member is made from a soft material.

The surface layer 2s of the intermediate support member 2 may be made from, e. g., a felt-like material. At least one inner layer 2m of the intermediate support member 2 is made from a fabric of substantially high tear resis- tance such as a metallic fabric. One advantageous choice for the middle layer is a metal wire fabric.

The intermediate support member 2 typically comprises two surface layers 2s and one inner layer 2m. The surface layer 2s is of a felted-surface polymer fabric such as a polyester-resin-bonded fabric.

Advantageously, the intermediate support member 2 is made from a flexible material, whereby it can be rolled about the support roller element.

The layers 2s, 2m are bonded to each other by glueing.

Also other similar bonding methods may be used.

In a typical application, the dimensions of the inter- mediate support member over the stacking area are about 2-4 m wide by 5-9 m long. The thickness of the layers in the intermediate support member are determined by the material used. The surface layers may have a thickness in the order of 2-3 mm, while the middle layer is typical- ly not thicker than 1 mm. Obviously, the dimensions of the intermediate support member may depending on the application vary even in a wide range from the above- cited typical figures.

The invention also concerns an intermediate support member alone particularly suited for use in a stacking apparatus of the type described above. Then, the inter- mediate support member 2 is made from a multilayer mate-

rial in which at least one surface layer 2s is made from a soft material and at least one second layer 2m of a material having a high tear resistance.

The apparatus and intermediate support member according to the invention may be used in applications related to the sheet-manufacturing industry in conjunction with, e. g., a trim-sawing line of sheets.

To those versed in the art it is obvious that the inven- tion is not limited by the exemplifying embodiments described above.