Device for slotting and creasing a sheet cardboard material

Abstract: The invention relates to a device for slitting and creasing sheet cardboard material, the device including a plurality of sheet cardboard material slitting and driving assemblies, including a plurality of slitting heads (7,9,7',9') and driving heads (5). The main feature of the invention is that the slitting heads (7,9,7',9') can be disconnected from the driving heads (5), to be driven independently from the driving heads (5), and that the cardboard sheet slitting and driving assemblies are supported by a supporting carriage for adjusting the spacing of parallel slitting heads (7,9,7',9').

Description: BACKGROUND OF THE INVENTION The present invention relates to a device for slotting and creasing sheet cardboard material. Prior cardboard processing machines which are specifically designed for processing sheets of cardboard, provide the cardboard sheets with suitable cross slots and creasing, for allowing the cardboard sheet to be easily folded in order to form a cardboard box or other like packaging article. A first type of said prior cardboard material slotting and creasing machines comprises a supporting shaft supporting a plurality of slitting heads, including a plurality of slitting blades which are caused to quickly turn by their turning supporting shaft. The slotting heads, in particular, are coupled to suitable counter-slotting elements, so that the slotting blades can cut through the cardboard sheet fed thereunder, to provide the mentioned throughgoing slots. A second type of prior machines comprises a first supporting shaft supporting a plurality of creasing heads and, downstream of said first shaft, a second supporting shaft supporting a corresponding plurality of slitting heads aligned with the creasing heads. The above mentioned machines can also operate with cardboard sheets having a pitch greater than the diameter of the slitting head. However, in such a case, it would be necessary to rise the slotting head from the cardboard sheet and stop the rotary movement of the machine for a time necessary for allowing the cardboard sheet to be fed to an operating position thereat it can be properly cut through by the slotting blade. In such an operation, however, the cardboard sheet is not perfectly held and guided, and, accordingly, it is not possible to provide a very accurate position of the cardboard sheet being processed. A further drawback of this second type of cardboard sheet processing machine is that the stopping and driving again of the shaft supporting the slotting heads would require a very great amount of power, because of the comparatively large mass of the mentioned shafts to be turned, which power consumption would negatively affect the cost of the finished cardboard article. Moreover, because of the mentioned large mass of the slitting head supporting shaft, the mentioned prior machines do not allow to obtain a great yield. Document EP-A-0 752 299, on which the preamble of claim 1 is based, discloses a slotting device having independently driven knives. SUMMARY OF THE INVENTION Accordingly, the aim of the present invention is to provide such a cardboard sheet material slotting and creasing device having a very high yield, while requiring a comparatively low operation cost. Within the scope of the above mentioned aim, a main object of the present invention is to provide such a cardboard sheet material slotting and creasing device which can be used for a very broad range of cross and longitudinal sizes of the cardboard sheets to be processed, without the need of performing very complex and long adjustments. According to one aspect of the present invention, the above mentioned aim and objects, as well as yet other objects, which will become more apparent hereinafter, are achieved by a device for slotting and creasing a cardboard sheet according to claim 1. According to a preferred embodiment of the present invention, said slitting heads have a diameter corresponding to a sub-multiple of the cardboard sheet feeding pitch. Moreover, the first and second shafts are driven by the main driving assembly of the slitting machine through a toothed pulley thereon a toothed belt is engaged. According to another preferred embodiment of the present invention, the fist and second shafts, supporting said slitting heads, are driven by brushless motors and comprise broached shafts. According to a further preferred embodiment of the present invention, the adjusting carriage is driven by a gear-motor unit allowing said carriage to slide in a direction substantially perpendicular to the cardboard sheet feeding direction in order to locate said slotting heads at a desired slotting point, depending on the size of the cardboard sheet being processed. Finally, to the cardboard sheet slitting and driving assemblies a plurality of counter-slotting heads and creasing heads mounted on a carriage which can be driven together with the adjusting carriage are coupled. The invention provides the following advantages with respect to the prior art. At first, very important advantage of the invention, is that the slotting heads can be driven independently from the driving heads and that said slotting heads are supported by the mentioned adjusting carriage and not by the turning shaft thereof. This means that, as the length of the cardboard sheet is larger than the extension of the slitting heads, and it would be accordingly necessary to stop and then recover again the turning movements of the slotting heads, said slotting heads can be driven by a power much less than that which would be necessary in prior machines, in which the slotting heads are mounted on shafts which also operate for supporting said heads. Moreover, it should be apparent that, in the machine according to the invention, the feeding and proper locating of the cardboard sheet are assured by the provision, downstream of the first driving head assembly, of the second driving head assembly, and by the fact that the toothed belt associated therewith is always held in contact with the cardboard sheet material. A further advantage of the present invention is that the diameter of the slotting heads corresponds to a half of the feeding pitch of the cardboard sheet; thus, the brushless motors can be operated with the same operation speed as the machine, as the length of the cardboard sheet being processed is not larger than the extension of the slotting heads, thereby providing a high operation performance for given lengths of the cardboard sheets to be processed. BRIEF DESCRIPTION OF THE DRAWINGS Further advantages and characteristics of the present invention will become more apparent hereinafter from the following detailed disclosure, given by way of an illustrative but not limitative example, with reference to the accompanying drawings, where: Figure 1 is a partially cross-sectioned view, cross-sectioned according to a plane parallel to the cardboard sheet feeding direction, of the device according to the invention; and Figure 2 is a cross-sectional view, as cross-section according to the broken line A-A, of the slotting and creasing device according to the invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following disclosure reference will be made to some preferred embodiments of the present invention, which are illustrated by way of a not limitative example of several possible variations of the invention. Figure 1 shows the slotting and creasing device according to the invention. The device comprises a supporting carriage 18, sliding on rails 25, supporting a plurality of slotting and creasing assemblies, of which the slotting and creasing assembly shown in Figure 1 comprises a first assembly or set of slotting heads 7 and 9 and a second assembly or set of slotting heads 7' and 9', and comprising moreover toothed pulleys 2 and 3. The slotting heads 7, 9 and 7', 9' are respectively mounted on a first and second broached shafts 6 and 6', which are arranged at a position substantially parallel and so that the slotting heads 7, 9 and 7' and 9' will operate on a same plane; moreover, between the heads 7, 9 and 7', 9' counter-creasing wheels 32 are provided. Each said slotting head is provided with slotting blades 8 which, as rotatively driven by the rotary broached shafts 6, 6', will operate on the cardboard sheet 14 in order to provide suitable slots therethrough. The slotting and creasing assembly comprises moreover toothed pulleys 2 and 3, which are mounted on a broached shaft 1, which is driven by the main driving assembly of the machine. Said elements included in said slotting and creasing assembly of Figure 1, are coupled by a belt transmission, including a toothed belt 4 associated with suitable belt tension elements 27. The belt 4, in cooperation with a first counter-slotting head 12, 13 assembly and a second counter-slotting head 12', 13' assembly, as well as with creasing heads 31, will define a space therethrough the cardboard sheet 14 being processed is entrained. The slotting heads 7, 9 and 7', 9' have an extension corresponding to a sub-multiple of the feeding pitch of the cardboard sheet 14. More specifically, said counter-slotting heads 12, 13 and 12', 13' are mounted on expanding shafts 11 whereas the creasing heads 31 are mounted on an expanding shaft 30. Each said counter-slotting head is provided with counter-blades 16, 17 cooperating with the slitting blades 8 in order to provide the cardboard sheet 14 with a plurality of throughgoing slots. The assembly of said counter-slotting and creasing elements can slide on axes 29, to which said assembly is coupled by coupling elements 28, through a carriage 33 which is driven jointly with the mentioned carriage 18. More specifically, the carriage 18 is driven by a geared motor unit 23 allowing said carriage to slide on shafts 20 in turn coupled, by coupling elements 22, to the support 26 supporting the rails 25. Figure 2 is a cross-sectioned view, taken substantially along the broken section line A-A, showing the slotting and creasing device according to the present invention. More specifically, the slotting heads 7, which are mounted on said broached shaft 6, can be disconnected from the driving heads 5, thereby allowing said slotting heads to be driven independently from the driving heads 5, in order to provide through the cardboard sheet 14 the mentioned throughgoing slots, by the slotting blades 8, at any desired time. The same disclosure made about the slotting heads 7 could be also made with respect to the slotting heads 9. The slotting and creasing device according to the invention will operate as follows. The broached shaft 1 is driven by the main driving unit of the machine, and in turn said shaft will rotatively drive the toothed pulleys 2, 3 which will in turn rotatively drive the toothed pulleys 5 through the toothed belt 4. In this connection it should be pointed out that the pulleys 5 and toothed belt 4 would also operate, as stated, as driving heads, thereby they will be driven synchronously with the machine. The broached shaft 6 is driven by a geared motor unit including brushless motors, provided for causing the heads 7 to perform a revolution for each passage of the cardboard sheet, while stopping waiting for a following cardboard sheet. The slotting blades 8, mounted on the slotting heads 7 and 9, will successively cut through the cardboard sheet 14 to provide the mentioned slots therethrough. Since the slotting heads 7, 9 are supported by their supporting carriage 18, and not by the driving shaft therefor, as it occurs in prior machines, said slotting heads can be stopped and turned again in a very easy manner and with a very reduced power consumption. Actually, the expanding shafts 11 and 30 will be rotatively driven by the main driving unit of the machine, thereby driving in turn the counter-slotting heads 12, 13 and 12', 13' as well as the creasing heads 31. Since th counter-slotting heads 12, 13 and 12', 13' and the creasing heads 31 will also operate as driving heads, they will always operate synchronously with the machine. The carriage 18 can be cross driven along the machine in order to locate the heads at a desired slotting point, depending on the size of the cardboard sheet being processed, in which the slotting blades 8 will be engaged between the counter-blades 16 and 17. In such a case, the expanding shafts 11 and 30 will release the counter-slotting heads 12 and 13 as well as the creasing heads 31. At this time, the carriage 18, during its movement, will entrain the counter-slotting heads 12, 13 and 12', 13' and the counter-slotting heads 12, 13 and 12', 13' associated with the carriage 33 sliding on the axes 29, thereby entraining the creasing head 31. Then, the supporting carriage 18 will be driven along the rails 25 by the geared motor unit 23. With the carriages all located in their set positions, the expanding shafts will lock again the counter-slotting heads 12, 13 and 12', 13' as well as the creasing heads 31. In this connection it should be moreover pointed out that the slotting heads can be designed, depending on several possible constructional variations of the inventive device, with a diameter corresponding to a sub-multiple of the cardboard sheet feeding pitch, and a diameter corresponding to a half of the cardboard sheet feeding pitch, or also with a diameter corresponding to the feeding pitch of the cardboard sheet. The transmission system for transmitting the driving motion from the pulleys 2 and 3 to the driving heads, can comprise, in addition to the toothed belt 4, other mechanical equivalent means, for example a trapezoidal belt, a driving chain or a gear system. While the invention has been disclosed with reference to a preferred embodiments thereof, it should be apparent that the disclosed embodiments are susceptible to several modifications and variations all of which will come within the scope of the accompanying claims.

Claims: A device for slotting and creasing a cardboard sheet (14), comprising a plurality of cardboard sheet slotting and driving assemblies, each said slotting and driving assembly including a first and a second plurality of slotting heads (7, 9; 7', 9') and driving heads (5), said driving heads (5) being designed for feeding said cardboard sheet (14) to be slotted, characterized in that said first and seccond plurality of slotting heads and driving heads are removably coupled and independently drivable said slotting heads (7, 9 and 7', 9') being respectively mounted on a first and a second parallel shafts (6, 6'), said cardboard sheet slotting and driving assemblies are supported by a same supporting carriage (18) for adjusting the spacing between parallel slotting heads, and that said shafts (6, 6') are broached. A device according to Claim 1, characterized in that said first and second plurality of slotting heads (7, 9; 7', 9'), have a diameter corresponding to a sub-multiple of the cardboard sheet (14) feeding pitch. A device according to Claim 1, characterized in that said first and second broached shafts (6, 6') are rotatively driven by a main driving unit of the slotting machine through toothed pulleys (2, 3) on which a toothed belt (4) is entrained. A device according to one or more of the preceding claims, characterized in that for each said slotting and driving assembly a plurality of counter-creasing wheels (12, 13; 12', 13'), arranged between said slotting heads, are provided. A device according to one or more of the preceding claims, characterized in that said slotting head-supporting first and second broached shafts (6, 6') are driven by brushless motors. A device according to one or more of the preceding claims, characterized in that said carriage (18) is driven by a geared-motor unit (23) causing said carriage to slide in a direction substantially perpendicular to the feeding direction of said cardboard sheet (14) in order to locate said slotting heads at a set slotting point, depending on the size of the cardboard sheet (14) being processed. A device according to one or more of the preceding claims, characterized in that to said cardboard sheet material slotting and driving assemblies are coupled a plurality of counter-slotting heads and creasing heads (12,13;12',13') which are mounted on a supporting carriage (33) which can be driven together with said first-mentioned carriage (18).

Inventors: BENZONI RINALDO, BENZONI, RINALDO
Applicants: ENGICO S R L, ENGICO S.R.L.
Application year: 1999
Main classification: B31B1
IPC codes: B26D3, B26D7, B31B1