PUNCHING UNIT

Abstract: A punching unit is included in a machine for manufacturing blanks, in particular corrugated fibreboard or paperboard. The unit comprises means (16) for feeding blanks (15) between two rotatable rolls, one of which (2) is provided with punching tools whereas the other (6) serves as a punching die. The tool roll is provided with means (3) which allow the punching tools to be mounted in desired positions on the roll. The punching unit comprises at least two tool rolls (1, 2) and means (11, 7, 8) for making an optional roll take a working position adjacent to the die roll (6) while at the same time the other takes a ready position, in which it is accessible to mounting of punching tools. Moreover, means (20) are included for temporary locking of the tool rolls in the positions taken, which locking is easily releasable for changing the positions of the rolls.

Description: PUNCHING UNIT The present invention relates to a punching unit included in a machine for manufacturing blanks, in particular corrugated fibreboard or paperboard, said unit comprising means for feeding blanks between two rotatable rolls, one of which is provided with punching tools whereas the other serves as a punching die, the tool roll being provided with means which allow the punching tools to be mounted in desired positions on the roll. A drawback of prior-art punching units of this kind, which are usable for punching holes, slots and the like, is that the machine must be stopped when punching tools need to be replaced or the punching pattern is to be changed. This results in expensive downtime periods, which are particularly consequential when changing between short series. Also in long series, worn-out tools may need to be replaced with reground ones, which today makes it necessary to stop the machine and keep it idle when the work is carried out. The main object of the present invention is to pro- vide a punching unit in which the downtime when changing or moving the punching tools can be reduced to a minimum to allow substantially continuous operation. The invention is based on the knowledge that this can be achieved by using at least two tool rolls, so that one roll can always be located in a working position at the same time as another roll is accessible to replacing of the punching tools or changing of the positions of the tools on the roll. What is particularly characteristic of a punching unit of the kind mentioned in the introductory part is that the punching unit comprises at least two tool rolls, means for making an optional roll take a working position adjacent to the die roll while at the same time the other takes a ready position, in which it is accessible to mounting of punching tools, and means for temporary locking of the rolls in the positions taken, which locking is easily releasable for changing the positions of the rolls. When using a punching unit of this kind, the downtime when changing the punching tools can be reduced to the time required for changing the positions of the two tool rolls, which can be done very quickly, whereby the punching unit can be in substantially continuous opera- tion. It is preferable that the rolls are rotatably mounted in bearings in a common revolver disk at each end and that means are arranged for synchronous turning of the two revolver disks when changing between the posi- tions of the rolls. The revolver disks are suitably arranged to interact with locking means, which lock the disks temporarily in the positions in which a tool roll is located in a working position adjacent to the die roll. Additional features of the invention are stated in the claims. The invention will be described in more detail below with reference to the embodiment which is shown as an example in the accompanying drawing. Fig. 1 is a schematic perspective view of a punching unit according to the invention. Fig. 2 is a cross-sectional view of the unit according to Fig. 1. In the drawing, 1 and 2, respectively, designate the two tool rolls, which are provided with holes 3 or other means for attaching punching tools in desired positions on the roll. The punching tools (not shown) are usually mounted on the cylindrical surface area 4 of bent panels 5 of plywood or like material. A die roll is designated 6 and is usually provided with a rubber coating, which constitutes a punching die for the tools on the tool roll which is located in the working position adjacent to the die roll. In the shown embodiment, the two tool rolls 1 and 2 are mounted in bearings at each end of a common revolver disk 7 and 8, respectively, suitably in such manner that they can be somewhat displaced for fine adjustment transversely of the feeding direction of the blanks. The tool rolls are each driven by a servomotor 9 and 10, respectively, mounted on the revolver disk 7. The revolver disk 7 is driven by a motor 11 by means of a chain 12 and a gear wheel 13, and the disk 8 is driven in synchronisation with the same by means of the shaft of the motor 11. The die roll 6 is driven by a servomotor 15 mounted on one of the end supports 14. The punching unit is adapted to punch blanks 15, which are fed by a conveyor 16 to the nip between the tool roll 2, which is in working position, and the die roll 6. A piece of sheet-metal is designated 17 and prevents tools, when being mounted on the upper tool roll 1, from falling down onto blanks which are being punched. Reference numeral 18 refers to a bridge, on which the operator can stand when mounting the tools on the tool roll 1 in the ready position. In this embodiment, the revolver disks 7 and 8 are provided with a circumferential slide bearing coating 19, which interacts with a corresponding coating in the side supports. The revolver disks can be locked in predetermined positions with the aid of locking means 20, which are pressed into recesses in the revolver disks 7, 8. The locking means can be operated by means of, for instance, air cylinders 21. Moreover, the device suitably comprises means which in the locking positions exert a force on the revolver disks, which eliminates any possible play in their bearings. This also prolongs the service life of the bearings and ameliorates the precision of the punching. The function of the described punching unit is as follows . In the position shown in the figures, the blanks 15 as fed are punched by means of the tool roll 2 and the die roll β. During this operation, the second tool roll 1 can be prepared for a subsequent punching operation by punching tools being mounted in desired positions on the same. When the punching of the current series of blanks 15 is finished and the punching of the next series is to begin, the locking means 20 are released and the revolver disks 7 and 8 are turned through 180° by means of the motor 11, whereupon they are locked in the new positions with the aid of the locking means 20 and the associated recesses in the revolver disks 7 and 8. After this, the punching of the new series of blanks can be initiated. This method allows a substantially continuous punching with very short stoppages for the change between different series of blanks. This is especially advantageous when punching short series, but it is also advantageous in long series, for instance, when worn-out tools need to be replaced with reground ones. The mounting of tools on the tool roll in the ready position can also be done without having to work under pressure, which reduces the risks of making mistakes. The punching unit according to the invention can also be supplemented with a feed roll which is mounted in bearings in the revolver disks 7 and 8 and which can interact with the die roll 6 in a turning position to let blanks pass through the unit without any machining of the same. The two tool rolls are then idle. The locking means 20 are suitably arranged to lock the revolver disks in such a position that the cutting means cuts through the blank at a point where it is supported by the die roll. Above, the invention has been described in connection with the embodiment shown in the drawing. It can, however, be modified in many ways within the scope of the claims. Thus the tool rolls 1 and 2 can be mounted in another mechanism, which allows them to change between a working position adjacent to the die roll and a ready position, in which they are accessible to mounting of punching tools. Furthermore, the turning, locking and mounting of the shown revolver disks can be varied as desired. Besides being mounted in a slide bearing, the revolver disks can thus, as an alternative, be mounted by means of roller bearings, needle bearings or the like.

Claims: CLAIMS 1. A punching unit included in a machine for manu- facturing blanks, in particular corrugated fibreboard or paperboard, said unit comprising means (16) for feeding blanks (15) between two rotatable rolls, one (2) of which is provided with punching tools whereas the other (6) serves as a punching die, the tool roll being provided with means (3) which allow the punching tools to be mounted in desired positions on the roll, the punching unit comprising at least two tool rolls (1, 2), means (11-13, 7, 8) for making an optional tool roll take a working position adjacent to the die roll (6) while at the same time the other tool roll takes a ready position, in which it is accessible to mounting of punching tools, and means (20) for temporary locking of the tool rolls in the positions taken, which locking is easily releasable for changing the positions of the rolls, c h a r a c - t e r i s e d in that said locking means (20, 21) comprise blocking members (20) which are arranged to project into recesses in the peripheries of the revolver disks (7, 8), and that said locking means (20, 21) are arranged to allow a displacement of the position of the point of punching in relation to the feeding direction of the blanks (15) by adjustment of the locking positions of the revolver disks (7, 8). 2. A punching unit according to claim 1, c h a r a c t e r i s e d in that the tool rolls (1, 2) are rotatably mounted in bearings in a common revolver disk (7, 8) at each end, and that means (11) are arranged for synchronous turning of the two revolver disks when changing between the positions of the rolls. 3. A punching unit according to claim 2, ch a r - a c t e r i s e d in that, besides said tool rolls (1, 2) , it also comprises a feed roll which is mounted in bearings in the revolver disks (8, 9) and which in co- operation with the die roll (6) is arranged to let the blanks (15) pass through the unit when no punching is desired. 4. A punching unit according to claim 1 or 2, ch a r a c t e r i s e d in that the tool rolls (1, 2) are arranged to move along a common circular arc when changing between the two positions. 5. A punching unit according to any one of claims 1- 4, c h a r a c t e r i s e d in that the peripheral sur- face of the revolver disks (7, 8) is provided with a slide bearing coating (19) which is arranged to interact with a corresponding coating in a surrounding bearing housing. 6. A punching unit according to any one of the pre- ceding claims, cha r a ct e r i s e d in that the revolver disks (7, 8) are driven by means of gear wheels (13) or gear rims, which are arranged on the same and which are driven by a motor (11) by means of a respective chain (12) .

Inventors: ANDREN ERIK, ANDREN, ERIK
Applicants: ANDREN ERIK, EMBA MACHINERY AB, ANDREN, ERIK
Application year: 1999
Main classification: B26F1
IPC codes: B26D7, B26F1, B31B1