Patent Application
20080307940
The present invention relates to a table for a chopper folding device, of the type comprising
a surface for application of products to be folded, the application surface extending along an application plane,
a folding opening suitable for the passage of the products to be folded,
at least one first guide portion disposed adjacent to the folding opening and comprising a first guide surface inclined with respect to the application plane.
Chopper folding devices used in printing presses are known in the art. Such a chopper folding device is for example known from the document FR-A-2 546 818. These chopper folding devices include a folding table provided with a longitudinal slot through which signatures or leaflets are pushed during the folding by means of a folding blade.
The folding table includes an application surface on which the signatures to be folded are applied. The application surface is provided with a plurality of suction holes which serve to hold the signature against the table.
It has been found that the known chopper folding device leads to folding defects, particularly on the outer edges of the signatures when the folding speed is considerable.
These defects appear predominantly, but not exclusively, when the gsm weight of the paper used for the signatures is low.
The object of the invention is to enhance the quality of folding of the signatures, particularly at high folding speeds and with a low gsm weight of the paper.
To that end, the invention relates to a table for a chopper folding device of the type indicated, wherein the table comprises guiding means which are suitable for urging the product to be folded towards the first guide surface and which are provided with a first main suction hole which opens on the first guide surface.
According to particular embodiments, the table according to the invention includes one or several of the following features:
the table comprises a second guide portion disposed adjacent to the folding opening and facing the first guide portion, this second guide portion comprising a second guide surface inclined with respect to application plane, and the table comprises a second main suction hole which opens on the second guide surface;
the table defines a front part and a rear part according to a direction of displacement of a product to be folded on the table, and the or each main suction hole is disposed in a front half of the associated guide portion;
the or each guide portion comprises an auxiliary suction hole, and this auxiliary suction hole is offset from the main suction hole;
the or each auxiliary suction hole has a length less than the length of the associated main suction hole;
the table comprises, for each main suction hole, a main air duct which opens in the associated main suction hole and an auxiliary air duct which opens in the associated auxiliary suction hole, and the locations of the mouths of the main and auxiliary air ducts are disposed at ends of the main and auxiliary suction holes which are directed towards one another;
the or each main suction hole or, as the case may be, each auxiliary suction hole is situated at a location of the associated guide surface having an inclination of less than 45° relative to the application surface;
the or each guide surface has a curved cross-section, particularly in the shape of an arc of a circle;
the application surface has two halves separated by a plane of separation, and the table has a first group of suction and application holes extending over a first zone of the application surface and a second group of suction and application holes extending over a second zone of the application surface, the second zone is disposed on the same half of the application surface as the first zone, and each group of application holes is provided with an individual suction connector;
each group of application holes includes a vacuum chamber in which the application holes of the associated group of holes open and in which the associated suction connector opens;
the first and the second zones are offset from one another in the longitudinal direction;
the first and the second zones are offset from one another in the transverse direction;
the table includes a vacuum device connected to one or each of the main and/or auxiliary suction holes; and
an application vacuum device is connected to the holes of each of the groups of holes.
The invention further relates to a chopper folding device of the type comprising
a chopper folding blade,
two folding rollers, and
a chopper folding table,
wherein the chopper folding table is a table as defined above.
The present invention will be better understood by reading the following description, which is given solely by way of example and with reference to the appended drawings, in which:
The chopper folding device 2 bears a chopper folding blade 4, two folding rollers 6, 8 and a chopper folding table 10. The chopper folding device 2 also includes a plurality of conveyor belts 12.
The chopper folding blade 4 extends along a blade plane PL and it is movable along this blade plane PL alternately between a signature passing position and a signature folding position.
The folding rollers 6, 8 are disposed so as to be movable in rotation about two respective axes X-X. The two axes X-X are parallel, such that the folding rollers 6, 8 define a signature folding gap 14 between them.
The conveyor belts 12 are disposed in two rows parallel alongside one another and the two rows define a transport gap 16 between them. The conveyor belts 12 guide signatures 17 to be folded into this gap 16 (see
The signatures 17 are guided by the belts 12 in a conveying direction S. The conveyor belts 12 are suitable for guiding the signatures 17 to a folding position.
The chopper folding table 10 includes a base plate 18 provided with an application surface 20 on which the signatures 17 to be folded are applied. This application surface 20 defines an application plane PA extending perpendicular to the blade plane PL. The base plate 18 delimits a folding opening 22 extending parallel to the conveying direction S. The length of the folding opening 22, measured in the conveying direction S, is at least equal to the length of the signatures 17. The folding table 10 also defines a front part 24 and a rear part 26 according to the conveying direction S.
The application surface 20 is divided into two surface halves 20A, 20B which are separated by a plane of separation formed by the blade plane PL.
The chopper folding table 10 is also provided with a first guide portion 28 and a second guide portion 30. The guide portions 28, 30 are disposed adjacent to the folding opening 22 and delimit the latter. The first guide portion 28 includes a first guide surface 32, whilst the second guide portion 30 includes a second guide surface 34. Each of the guide surfaces 32, 34 is inclined with respect to the application plane PA. In this case each of the first 32 and second 34 guide surfaces has a curved cross-section, particularly in the shape of an arc of a circle.
The chopper folding table 10 includes guiding means suitable for urging the signature 17 during folding on the one hand towards the first guide surface 32 and on the other hand towards the second guide surface 34.
To that end, the chopper folding table 10 includes a first main suction hole 36 (
The chopper folding table 10 is also provided with a first main air duct 40 and a second main air duct 42 which opens in the associated main suction hole 36, 38.
The first guide portion 28 comprises a first auxiliary suction hole 44 and the second guide portion 30 includes a second auxiliary suction hole 46. Each auxiliary suction hole 44, 46 is offset, upstream in the conveying direction S, from the associated main suction hole 36, 38. In this case each auxiliary suction hole 44, 46 is disposed in an upstream half of the associated guide portion 28, 30.
Each auxiliary suction hole 44, 46 has a length L2 measured in the conveying direction S. This length L2 is less than the length L1. Due to this characteristic, the signature is better guided in a head zone than in the region of a tail zone. Moreover, since the length of the signature may vary from one series of signatures to another, the auxiliary suction holes 44, 46 are always entirely covered by a signature irrespective of its length.
Also the folding rollers 6, 8 may have grooves for local release of the signature. In this case the main holes 36, 38 and the auxiliary holes 44, 46 are aligned in the direction S with the local release grooves.
The chopper folding table 10 also has two auxiliary air ducts 48, each of these ducts opening in the associated auxiliary suction hole 44, 46, as can be seen in
The main suction holes 36, 38 and the auxiliary suction holes 44, 46 are disposed at locations of the associated guide portion 28, 30 having an inclination of less than 45° relative to the application surface 20.
The chopper folding table 10 also has suction and application holes 50 which open on the application surface 20. The suction and application holes 50 are combined in a plurality of groups of holes G1, G2, G3, G4 which are illustrated in
The vacuum box 54 also delimits a vacuum chamber 53 in which the main suction ducts 40, 42 and auxiliary suction ducts 48 open.
Each vacuum chamber 52 is provided with an individual suction connector 56 separate from the suction connector 56 of the other vacuum chambers 52. As can be seen in
The chopper folding table 10 is also provided with a vacuum device (see
The device according to the invention functions in the following manner.
The signatures to be folded 17 are conveyed in the conveying direction S by the conveyor belts 12. As soon as the signature 17 covers the holes 50 it is urged against the application surface 20 of the base plate 18. Then the chopper folding blade 4 is brought into its folding position and pushes the central part of the signature 17 through the folding opening 22. The central part of the signature 17 is gripped by the folding rollers 6, 8 and is driven downwards. During this operation the central part of the signature 17 is held against the guide surfaces 32, 34. The signature 17 is held flat against the guide portions 28, 30 until side edges of the signature 17 clear the main holes 36, 38 and auxiliary holes 44, 46.
Therefore the side edges of the signature 17 are not released abruptly and therefore do not “whiplash” just before they pass between the rollers 6, 8.
It will be understood that due to the suction holes 36, 38, 44, 46 the folding rate can be high without causing damage to the signatures 17, even if these signatures 17 comprise paper of a low gsm weight.
| Number | Date | Country | Kind |
|---|---|---|---|
| 07 55684 | Jun 2007 | FR | national |
