Finnish patent 94042 discloses a device for packaging envelopes, in which device envelopes, placed in a stack on a belt conveyor operating as a transfer device, are transferred in an upright position by means of the belt of the belt conveyor to separating means. Thus, the envelopes in the stack are transferred forward in the stack, in a transverse orientation with respect to their transfer direction. In this device, the length of the stack varies when a stopper, which forms a part of the packaging means, moves, wherein the foremost portion of the envelopes is always separated by pushing it aside for packaging by means of a pusher. New envelopes are constantly fed to the stack from the other end of the stack by means of a feeding device, known as such, and located in the end of an apparatus for producing envelopes.

The envelopes in the stack remain in a vertical position by resting against the adjacent envelopes.

Typically, flat articles in stacks, such as envelopes, are located in a stack substantially parallel to each other and in identical positions. If the flat articles in the stack are simultaneously placed also in an upright position, as in the above-described device, they have to rest against each other, and a stopper advancing with the stack has to be placed in the foremost end of the stack to support the envelopes in parallel within the stack. However, there are some flat articles which have such a structure that their thickness varies in different parts of the article. Such articles include, for example, envelopes and mailing bags which are filled from the short end, and in which the thickest part can be formed at a glued edge flap, the uplifted closing flap forming the thinnest part.

Furthermore, the envelopes can comprise stick-on labels or the like, wherein the thickness of the envelopes is increased in their area. When the envelopes or mailing bags in a stack rest against each other, elastic bending occurs in the envelopes and thus in the stack as well.

Especially when the length of the stack increases, the elastic bending and the variations in the thickness result in that the envelopes lean, or in the worst case, even fall forward or backward in the transfer

direction. In the above-described device, the elastic bending is intensified by a moving stopper arranged in the packaging device, against which the transfer device pushes the envelopes in the stack.

With reference to the facts described above, it is obvious that the leaning of the vertically directed flat articles in a stack complicates separating them in stacks of fixed size, and falling of the stack causes breaks in the operation of the transfer device.

U. S. patent 5,310,043 discloses a screw conveyor type auxiliary conveyor, which supports from above the stack to be transferred. The transfer effect is based on the rotation of the screw. The screw pitch defines the spaces which support the articles on the conveyor from the side.

The purpose of the transfer device according to this invention is to provide an improvement in the support conveyors according to prior art in the fieid. To attain this purpose, the transfer device according to the invention is primarily characterized in what will be presented in the characterizing part of the appended claim 1. A support conveyor following the movement of the actual conveyor forms a loop or a circle, by means of which articles can be supported in a controlled way at locations in which they would otherwise tend to assume an inclined position. The other embodiments of the invention are primarily characterized in what will be presented in the other claims.

The most important advantages of the transfer device according to the invention that could be mentioned are its simple structure and low expenses. By means of the invention, the transfer of flat articles in a stack can be performed in a controlled way, wherein breaks in the operation of the transfer device are avoided. A further advantage is that when flat articles are retained in the stack substantially parallel to each other, damaging of the articles due to mutual attrition of the articles is avoided, wherein the number of flawless products is increased when compared with prior art. Moreover, one advantage is that the length of the stack can be increased when compared with prior art, wherein the buffering capacity of the transfer device is increased. Furthermore, the device feeding the articles into the stack can be located further away

from e. g. a packaging device, because it is possible to increase the length of the stack, wherein the devices can be placed more freely respective to each other. With the transfer device according to the invention, flat articles can be easily transferred in upright position even longer distances.

In the following specification, the invention will be illustrated in more detail with reference to the appended drawings, in which Fig. 1 shows a preferred embodiment of the invention in a perspective view, and Fig. 2 shows a second preferred embodiment of the invention in a perspective view.

Fig. 1 shows a preferred embodiment of the invention in a perspective view. Articles E, in this case envelopes, are fed into a transfer device with a feeding device F, which comprises means, known as such, for guiding the articles upright into a stack advancing in the transfer device, and a counter and other control means belonging to the feed control system. With the control means, it is possible to adjust the feed rate of the articles E and the speed of a transfer means to be described below to be suitable with respect to each other. Furthermore, in the feeding device one article E is transferred at fixed intervals slightly aside as a marker article M, which defines the size of the stack portions to be separated later (the distance D between successive marker articles).

The transfer device comprises a base 1 and a transfer means 2 arranged to move with respect to the base 1 at a particular operating rate (arrow N1). The transfer means 2 is a belt moving in the plane of the base 1 and arranged to run for example through openings in the base 1, and this belt, preferably made of rubber, is most advantageously formed in the shape of a continuous loop, which is moved with a power source 11, such as an electromotor, which rotates drive wheel 12 of the belt via a suitable power transmission system.

The transfer means 2 is arranged to move flat articles E arranged in a stack P and placed on the transfer means 2, for example envelopes, in their transfer direction S. The articles E are moved forward in the stack

P on the transfer means 2, and at the same time, the articles E rest against each other. After the belt, the base 1 continues as a parallel table on which the articles are pushed and above which there are separating means, known as such, separating a portion of a particular size from the stack and pushing it from the side to further handling.

The articles E are preferably arranged transverse with respect to the transfer direction S, and substantially parallel to each other.

Consequently, the flat front surface EP, or the rear surface TP of the articles is located transversely with respect to the transfer direction S.

In the presented advantageous embodiment, the articles E are upright, and their transfer direction S coincides with the direction of the operating rate N1 of the transfer means 2. The base 1 and the transfer means 2 can also be arranged in a sloped position slightly deviating from the horizontal position, wherein articles E are transferred in the stack P in the transfer direction S slopingly downwards or upwards.

The stack P contains a bottom plane S4 resting on the transfer means, and free planes S1, S2, S3 formed of the other edges of the articles not resting on the transfer means 2.

In the presented advantageous embodiment, the transfer device comprises a follower device 3 comprising at least one support conveyor 4. The support conveyor 4 is formed for example in the shape of a cylindrical coil spring made of metal or plastic and arranged as a closed loop in its longitudinal direction. Thus, the support conveyor 4 circulates as a continuous loop controlled by two or more reversing wheels 6.

These reversing wheels 6 are coupled to a power source 10, e. g. an electromotor, by means of a belt or chain traction 8 and a gear 9 in a power transmission system 7. If the motors have constant rotation speeds, the power transmission system 7 can be controlled to adjust the ratio between the operating rates N1 and N2 of the transfer means 2 and the support conveyor 4, respectively. The rotation speeds of the adjustable motors functioning as power sources 10,11, can be synchronized for the same purpose.

In the presented embodiment, the coil spring, arranged in the shape of a ring and functioning as the support conveyor 4, is at least partly

arranged to move in the direction of a straight line X1 substantially parallel with respect to any free plane S1, S2, S3 of the stack P at a given operating rate (arrow N2). Most advantageously, this straight line X1 is parallel to the transfer direction S. The support conveyor 4 is located within a substantially constant distance from the transfer means 2, above the stack P. The part of the support conveyor 4, which is stretched between the reversing wheels 6 to be substantially horizontal in connection with the stack P, is parallel to the straight line X1. Thus, also the operating rate N1 of the transfer means 2, and the operating rate N2 of the support conveyor 4 are substantially equal.

The support conveyor 4 comprises preferably several contact means 5, which are arranged to support a portion PO of the stack P, moving in the transfer direction S and formed of one or more flat articles E, when the support conveyor 4 and the transfer means 2 are moving. The support takes place in such a way that viewed from the transfer direction S, the front surface SE or the rear surface ST of the portion PO of the stack rest at least partly against the contact means 5, to retain the articles of the portion PO of the stack substantially parallel to each other. The contact means 5 are formed of spiral parts of the coil spring, functioning as the support conveyor 4 in the presented embodiment, against which spiral parts the articles E rest. The function of the transfer means 2 is to transfer the articles E placed on top of it in the transfer direction S by means of a frictional force between an article E and the belt of the transfer means 2. The function of the contact means 5 of the support conveyor 4 is to follow the article E at the operating rate N2 of the support conveyor and to provide support when the articles E tend to lean, to prevent falling and/or leaning. When the direction of the operating rate N2 of the support part 4 deviates from the transfer direction S and is, however, parallel to any of the free planes S1-S3 of the stack, sliding of the contact means 5 along the edge of the article E occurs when the article E is resting against the contact means 5. Consequently, the operating rate N2 of the support part 4 has to be adjusted in such a way that the speed component of the operating rate N2 corresponding to the direction of the operating rate N1 of its transfer means 2 is equal to the operating rate N1.

The material of the coil spring can be flexible to such an extent that the contact means can accommodate to and bend by the effect of articles entering between two successive contact means.

In the presented embodiment, the follower device 3 is arranged movable with respect to the base 1, wherein the distance from the support conveyor 4 to the stack P can be adjusted. Consequently, also the distance of the support conveyor 4 to the base 1 can be adjusted, wherein it is possible to handle stacks P whose dimensions vary in the vertical direction.

Fig. 2 presents another alternative for the follower device 3, in which the support conveyor 4 is a continuous conveyor loop according to the principle of Fig. 1. Structurally, the contact means 5 are here formed of strips, spikes, or the like, directed outwards from the strap-like or belt- like material of the loop and forming a compartmented or comb-like conveyor structure. The operating principe is the same as that in Fig. 1.

If broad strips are used as contact means, they are placed advantageously parallel to the planes of the flat articles, perpendicular to the transfer direction.

In all the aforementioned alternatives, the contact means 5 can be arranged at fixed distances along the conveyor track formed by the support conveyor 4. Thus, it is possible to make a stack portion PO of a fixed size to enter a gap formed by two successive contact means 5, depending on the rate of feeding the articles to the transfer means 2 and on the speed of the transfer means.--In some cases, the stack portion PO can consist of only one article E. With reference to Fig. 1, for example, the up-lifted closing flaps of the envelopes, being thin parts, fit one by one in the spaces between the densely spaced contact means 5. Consequently, it is possible to use the contact means 5 located at fixed intervals to arrange the articles in closely defined mutual compartments in the stack P.

The contact means 5 can be flexible to such an extent that the size of the compartments is not predetermined. For example, the broad strips can be arranged flexible in the transfer direction. Similarly, the alternative presented in Fig. 2, can be modified in such a way that the

outwards directed contact means 5 are densely spaced flexible spikes or bristles, i. e. the means form a brush-like support. Consequently, the articles E are located in more random positions with respect to each other when they become supported by the support conveyor 4, but with this the primary purpose of the invention is achieved, i. e. the entire stack is held straight.

The range of action of the support conveyor 4 can vary in the direction of transfer of the stack. As presented in Fig. 1, the articles E come into contact with the support conveyor after the feeding device, after travelling some distance on the transfer means 2. The effect of the support conveyor can cease before the range of action of the separating means.

The support conveyor 4 is advantageously located in such a way that it travels at the upper free plane S2 of the stack P, i. e. directly above the path of the stack P. Thus, the contact means 5 support the articles E at their upper edges. However, it is also possible to arrange the support conveyor 4 at another free plane S1, S3, i. e. to support the stack from the side. In that case, however, it may be necessary to arrange a fixed guide on the opposite side to ensure that the stack remains in connection with the support conveyor 4. If the stack contains marker articles M protruding in one free plane S3, as in Fig. 1, they have to be taken into account in the structure of the support conveyor 4, if it is desired to place the support conveyor at this plane.

Furthermore, it is advantageous to provide the follower device 3 with several support conveyors 4, advantageously two parallel ones coupled to the same power source 10, as in Fig. 1, wherein they can be located symmetrically with respect to the central line of the transfer means 2, above the stack P. In this way, itis possible to support the articles E at two different points.

The invention is not restricted to the envelope type presented in the figures, in which the closing flap at the short end is lifted up and supporting takes place precisely at the closing flap, but it can also be used to support such envelopes in which the the closing flap is folded against the envelope. Furthermore, it can also be used in such transfer

devices in which the long sides of the envelopes are horizontally directed, even though stacks where the long sides are upright, as in Fig. 1, are more liable to lean or fall.

Moreover, the structure of the support conveyor 4 can be different from the ones presented in the figures. A loop-like support conveyor does not necessarily have to contain protruding structural parts, but its entire outer surface can be against the stack, wherein, in this case, it can be made of a suitable material, such as rubber or plastic. The material of the outer surface i. e. the contact surface of the loop can also be selected to be such that it can yield according to the external form of the stack, wherein the material can be such that in a contact occurring at a fixed pressure on the surface of the stack, such as on the edges of the envelopes, it thrusts faintly in the spaces between the articles.

Furthermore, the support conveyor does not need to be continuous, but it can consist of separate successive sections supporting the stack from a suitable direction. One alternative is to arrange the contact means 5 one after the other in a circular structure, such as the periphery of a rotary wheel or roll which is in contact with the stack in a particular sector. Thus, it is possible to provide the support conveyor with several means one after the other, such as wheels, rolls, or the like, arranged to rotate around an axis transverse to the transfer direction S of the stack and equipped with protruding contact means, wherein these rotating means have contact with the stack P via the contact means at regular intervals.