Method and device for decelerating or accelerating and/or for deflecting conveyed printed products

For decelerating, accelerating and/or deflecting conveyed printed products (3), pressing elements (1, 2) act on the printed products (3) with normal forces (F.sub.N). The action is carried out in a resilient manner by contact elements (4) fixed to spring elements (5) such that the time of the action on the printed product (3) is made longer. Thus an improved deceleration or acceleration effect is achieved by means of friction forces and/or a deflecting effect is achieved by means of a momentum.

FIELD OF THE INVENTION 
The invention lies in the field of conveyance of printed products and 
concerns a method for decelerating, accelerating and/or deflecting printed 
products conveyed as a stream of printed products in a conveying direction 
and a device for carrying out the method. Method and device are designed 
for decelerating or accelerating and/or for deflecting printed products 
which are conveyed in a conveying stream. 
BACKGROUND OF THE INVENTION 
When processing printed products it is sometimes necessary to change the 
conveying speed of the printed products between different processing 
steps. Thus e.g. the printed products leaving in succession the folding 
apparatus of a rotary printing machine at a high speed of e.g. 10 m/s must 
be decelerated to a lower speed of e.g. 1 m/s for forming a scaled stream. 
The scaled stream is basically formed by means of a feeding spider wheel 
synchronized with the folding apparatus. The printed products arriving at 
high speed impinge on the bottom of the compartments of the feeding spider 
wheel which runs at a lower speed. Without suitable means for controlling 
the impingement, the position of the printed product in the compartment of 
the feeding spider wheel is uncontrolled and/or at a slant angle. The 
impingement can also lead to damaging the printed product: the forward 
facing part of a printed product can be damaged directly by the 
impingement, while the backward facing part can be damaged by crushing due 
to the impingement. There are known methods and devices having the object 
to control the impingement, e.g. to reduce the impingement speed or to 
deflect the printed products. 
A method and a device for reducing the speed of impingement of a stream of 
printed products is e.g. described in the publication DE-34 06 069. Herein 
the printed products are gripped for a short time in the area of their 
upstream end, are decelerated and then are released. The decelerating 
device substantially consists of cam wheels running with reduced 
circumferential speed and functionally coupled with cooperating rings 
driven in the opposite direction. A similar device allowing simple 
adjustment to different format lengths of printed products while the 
machine is running is described in the patent application EP-0 390 736. 
These two mentioned inventions have the disadvantage that they only act on 
the printed products for a very short time and therefore the decelerating 
effect is accordingly small. 
Further devices for decelerating a stream of printed products are known 
from publication DE-43 16 051 and from patent application EP-0 484 653. 
Herein the printed products are decelerated by brushes. Both devices act 
on downstream ends of the products; therefore, the danger of damaging the 
printed products and of smudging the printing ink in areas of friction is 
considerable. 
None of the known methods and devices allow a selectable deceleration or 
acceleration and/or deflection of the printed products. 
SUMMARY OF THE INVENTION 
An object of the present invention is to show a method and to create a 
device which allow to selectably decelerate or accelerate and/or deflect 
printed products, whereby only one end of the printed products is acted on 
and nonetheless the method and device achieve an optimal deceleration, 
acceleration and/or deflecting effect. 
The basic idea of the inventive method consists in acting on the printed 
products with a pressing element and a counter element exerting periodical 
normal forces onto a stream of conveyed printed products whereby the parts 
contacting the printed products of at least the pressing element are 
resilient such that the acting time is increased. The pressing elements 
can e.g. be tappets fixed to spring elements which are fitted to a 
rotating cylinder. Due to the rotation of the cylinder, the contact 
elements periodically act on the stream of products by means of controlled 
impingement at the right moment. Due to the spring elements, the contact 
elements have contact with the printed products over a longer distance or 
for a longer time respectively and thus an improved effect is achieved. 
If the forces act on the two main surface of a printed product in the form 
of a pair of forces acting perpendicular to the main surfaces, directed 
against each other and aligned with each other mainly friction is caused. 
With this friction the printed product can be decelerated or accelerated 
selectably. Normal forces acting on the two main surfaces of the printed 
products as pairs of forces which are not aligned they cause a momentum 
acting on the printed product. With this momentum the printed product can 
be deflected. The deceleration or acceleration and the deflecting 
respectively can also be carried out with one single method and one single 
device.

DESCRIPTION OF PREFERRED EMBODIMENTS 
FIG. 1 shows a cross section of an embodiment of the inventive device. A 
first pressing element 1 and a second pressing element 2 are arranged 
substantially stationary such that a printed product 3 can be clamped 
between them. 
The pressing element 1 in this example comprises two contact elements 5 
which are arranged on spring elements 5. The spring elements 5 again are 
fitted to a drive element 6 for moving the contact elements. In the 
example shown in FIG. 1, the contact elements 4 are designed as tappets. 
They act periodically and in a synchronized manner on the stream of 
printed products 3. The spring elements 5 are e.g. flection springs 
(pieces of band or spiral spring); they are adjusted such that they are 
tensioned when the corresponding contact element 4 is in contact with a 
printed product 3. Near the pressing element 1 a template 7 is provide 
which influences the course of movement of the contact elements 4 e.g. by 
first tensioning the spring elements 5 and then letting the contact 
elements 4 impinge in a controlled manner onto a printed product 3 at 
exactly the right moment. The controlled, abrupt impingement of the 
contact element 4 onto a printed product 3 results in a sudden controlled 
clamping of the printed product 3 between pressing and counter element 1 
and 2. The pressing element 1 can comprise one contact element 4 only or 
more than two contact elements 4 and a corresponding number of spring 
elements 5. 
The counter element 2 is e.g. designed as a roller pressing with its 
surface 8 directly on one of the main surfaces 9 of the printed product. A 
feeding spider wheel, not belonging to the invention, which comprises 
compartments 11 for taking over printed products 3 is also shown. 
The inventive method is explained in connection with the examples according 
to FIGS. 2 and 3. In these Figures, as in FIG. 1, a pressing element 1 and 
a counter element 2 as well as a printed product 3 is shown 
diagrammatically. Pressing and counter element 1 and 2 rotate in opposite 
directions and the printed product 3 is conveyed between pressing and 
counter element 1 and 2 in a conveying direction indicated by arrow 12. In 
order to simplify the drawing, only one contact element is shown on 
pressing element 1. It is shown in three positions: in a waiting position 
4.1 (broken lines) and in a decelerating or accelerating position 4.2 in 
FIG. 2, as well as in a deflecting position 4.3 in FIG. 3. Due to the 
rotation of the drive element 6, the contact element is moved through the 
three positions in succession. In the waiting position the template 7 
keeps the contact element 4.1 at a distance from the printed product 3 by 
tensioning the spring element 5.1 and by pressing the contact element 4.1 
closer to the drive element 6. As soon as the contact element is moved out 
of the influence of the template 7 the spring element 5 is released partly 
and the contact element 4 impinges onto the upstream part of the printed 
product 3. This has the advantage that the downstream end is not affected 
and not damaged and that the printed product 3 is not crushed. 
Pressing and counter element 1 and 2 act on the printed product 3 
substantially with normal forces F.sub.N, i.e. forces which are orientated 
substantially perpendicular to the main surfaces 9, 9' of the printed 
product 3. Regarding the normal forces F.sub.N, two cases are to be 
distinguished. 
In a first case, which is shown in FIG. 2, the two normal forces F.sub.N 
act opposite to each other (are aligned to each other). In this case 
mainly friction forces act on the printed product 3 which friction forces 
can be exploited for decelerating and accelerating the printed product 3. 
The printed product 3 is decelerated if pressing and counter element 1 and 
2 which are in contact with it have a lower speed than the printed product 
or if they move in the opposite direction to the printed product. If a 
printed product 3 with a mass m is supplied with an initial speed v.sub.1, 
the pressing and the counter element 1 and 2 press the printed product 3 
with normal forces F.sub.N on both sides and the sliding friction 
coefficient between the main surfaces 9, 9' of the printed product 3 and 
the pressing elements 1 and 2 is .mu..sub.G, the end speed v.sub.2 of the 
printed product 3 after a decelerating distance s is: 
EQU v.sub.2 =(v.sub.1 -4.mu..sub.G F.sub.N s/m).sup.1/2. 
The printed product 3 is accelerated if the parts of the pressing and the 
counter element 1 and 2 which are in contact with the printed product 3 
have higher speeds than the printed product 3. For the end speed v.sub.2 
of printed product 3, the above formula is valid, whereby the minus sign 
must be replaced with a plus sign. Instead of the sliding friction the 
static friction can be exploited for decelerating or accelerating printed 
products 3 also. 
In a second case, which is shown in FIG. 3, two normal forces F.sub.N act 
on the printed product 3 in a not-aligned manner. In this case mainly a 
momentum acts on the printed product 3 which momentum can be exploited for 
deflecting the printed product 3. Deflecting printed products 3 can e.g. 
be necessary for bringing them precisely into the compartment 11 of the 
feeding spider wheel 10 shown in FIG. 1 or for pressing them against an 
area 13 inside such a compartment 11 for achieving a decelerating effect. 
The first case, described above, and the second case can also be carried 
out in the same one method and by the same one device. 
Two characteristics are substantial for the inventive method. Firstly, the 
acting elements 1 and 2 press periodically in a predetermined moment onto 
the stream of printed products such that they e.g. only affect the 
upstream part of printed products 3 and do not damage the downstream part. 
Secondly, pressing and counter element 1 and 2 act on the printed products 
3 over a longer time or over a longer distance respectively by which an 
improved decelerating, accelerating and/or deflecting effect is achieved. 
FIG. 4 shows a variant of the inventive method in which the counter element 
2 consists of two rollers 14.1, 14.2 and a belt 15 running on these 
rollers. The belt 15 can, at least on the side facing the printed product 
3, be supported by a supporting element 16. In this arrangement, two 
normal forces F.sub.N act on the printed product 3 over a longer distance; 
in other words: the deceleration or acceleration position respectively is 
maintained over a longer time while a deflecting position never occurs. 
This variant is especially suited for decelerating or accelerating printed 
products 3. 
In the method variant according to FIG. 5, the counter element 2 is a 
stationary, fixed wall. This arrangement is suited for decelerating 
printed products 3. The wall 2, in analogy to the belt 15 in FIG. 4, 
guarantees a longer decelerating phase. 
A longer decelerating or accelerating phase can also be achieved with the 
method variant shown in FIG. 6. Here pressing and counter element 1 and 1' 
are both designed as pressing elements according to the preceding figures, 
i.e. they are both equipped with spring elements 4, 4' and contact 
elements 5, 5'. The arrangement is symmetrical regarding the two main 
surfaces 9 and 9' of the printed product 3 and acts substantially 
symmetrically on the printed product 3. 
FIG. 7 shows a method variant in analogy to FIG. 2 for which the spring 
elements 5 are designed differently. Instead of flection springs, 
compression springs or coil springs are used for fitting the contact 
elements 4 to the drive element, which coil springs 5 can e.g. be guided 
in cylinders 17. These spring elements have a substantially identical 
effect as the spring elements according to FIGS. 1 to 6. 
A totally different pressing element is shown in FIG. 8. The drive element 
6 is substantially a hollow cylinder on which a sticking out spring 
element 5 is provided, which spring element carries a contact element 4. 
The hollow cylinder is mounted slewably around a stationary axis 19 such 
that during an acting phase it is driven by the products in conveying 
direction 12 and it is returned in the opposite direction during a waiting 
phase by a second spring element 18, e.g. a coil spring. Contact element 4 
is, in analogy to FIG. 7, e.g. fitted to the drive element 6 by a coil 
spring 5. Thus, a longer action of the pressing elements 1 and 2 on the 
printed products 3 is made possible. The stationary axis 19 is orientated 
perpendicular to the conveying direction 12. 
Obviously, combinations of the characteristics described above are also 
included in the teaching of the present invention. As an example for such 
a combination, FIG. 9 shows a first pressing element 1 according to FIG. 8 
and a second pressing element 2 according to FIG. 4. 
FIG. 10 shows diagrammatically the application of the inventive method for 
decelerating printed products 3 supplied in a linear manner. The printed 
products 3 are supplied with a small spatial density and with a high speed 
v.sub.1 in form of a non-scaled stream. They are decelerated according to 
the inventive method and are conveyed away with an increased spatial 
density and with a lower speed v.sub.2 &lt;v.sub.1. Pressing and counter 
element 1, 2 are advantageously applied to the upstream product ends in 
order to prevent the printed products 3 from being crushed. 
FIG. 11 shows diagrammatically the application of the inventive method for 
accelerating printed products 3 supplied in a linear manner. The printed 
products 3 are supplied with a large spatial density and with a low speed 
v.sub.1 in the form of a scaled stream. They are accelerated according to 
the inventive method and conveyed away with a smaller spatial density and 
with an increased speed v.sub.2 &gt;v.sub.1. Pressing and counter element 1 
and 2 are advantageously applied to the downstream product ends in order 
to prevent the printed products 3 from being crushed. 
Summarizing it can be said, that in the method for decelerating or 
accelerating and/or for deflecting conveyed printed products 3, at least 
one pressing element 1 and at least one counter element 2 periodically act 
on a stream of conveyed printed products 3 by applying forces F.sub.N 
either only to the downstream ends or only to the upstream ends of the 
printed products 3 which forces are orientated substantially perpendicular 
to the main surfaces 9, 9' of the printed products 3. As the forces are 
applied by springy members the acting time becomes longer. 
The device for carrying out the method has at least one pressing element 1 
and at least one counter element 2. With the help of the pressing and 
counter elements forces F.sub.N are applied substantially perpendicular to 
the main surfaces 9, 9' of the printed products 3. The at least one 
pressing element 1 comprises contact elements 4 fitted to a drive element 
6 via a spring element 5.