EP0269050A2

EP0269050A2 - Fastening assembly for piercing pins in a paper blanks perforating unit

Info

Publication number: EP0269050A2
Application number: EP87117241A
Authority: EP
Inventors: Lasse Sandgren
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-11-24
Filing date: 1987-11-23
Publication date: 1988-06-01
Also published as: FI78637B; SU1639424A3; FI864768A; EP0269050A3; FI864768A0; FI78637C; JPS63200996A

Abstract

The invention relates to a fastening assembly for piercing pins in a paper blanks perforating unit, comprising at least two rotating discs, namely a padded disc (2) whose periphery is provided with a circumferential array of holes (4) and a piercing disc (1) whose periphery is fitted with a circumferential array of piercing pins (3) which, as the discs are rotating, find their way into the holes (4) of said padded disc for piercing a paper pass ing therebetween, said piercing pins (3) being embedded in radially directed holes (7) in the rim of said piercing disc (1) and retained therein by means of retaining members (6) which are transverse relative to said holes.

Description

The present invention relates to a fastening assembly for piercing pins in a paper blanks perforating unit, comprising at least two rotating discs, namely a padded disc whose periphery is provided with a circumferential array of holes and a piercing disc whose periphery is fitted with a circumferential array of piercing pins which, as the discs are rotating, find their way into the holes of said padded disc for piercing a paper passing therebetween, said piercing pins being embedded in radially directed holes in the rim of said piercing disc and retained therein by means of retaining members which are transverse relative to said holes.
This type of perforating units are used in printing machines and laminating machines for producing paper blanks provided with arrays of perforations for the traction of computer printers.
In the prior art perforating units, the piercing pins are fastened to the piercing disc by means of hexagonal screws, which are tightened against the side face of a piercing pin by turning a key. The punching point of a piercing pin must be made of a relatively soft material, since a small-armed star figure is formed in its cutting edge by means of the hole in a padded element. This is done by rotating a piercing disc and a padded disc once around after setting the new piercing pins in position. On the other hand, the edges of the hole in said padded element are made of a hard, wear-resistant material.
The edges of a piercing pin become quickly worn and dull,. which is why all piercing pins of a piercing disc must be replaced at least every few days. A single perforating unit may carry e.g. four piercing pin wheels, each having possibly nearly a hundred piercing pins. A result of this is that the daily working time spent for the replacement of piercing pins may be as much as two hours, the entire production machine having to be stopped for that period of time.
An object of the invention is to provide a fastening assembly of the above-mentioned type for piercing pins, whereby a rapid replacement of piercing pins becomes possible.
This object is achieved on the basis of the inventive features set forth in the annexed claims.
A few embodiments of the invention will now be described in more detail with reference made to the accompanying drawings, in which

fig. 1 is a side view of the co-operating rim portions of a piercing disc and a padded disc.
Fig. 1a shows in a larger scale a piercing pin as seen towards its punching head or in the direction of arrow A in fig. 1.
Fig. 2 is a side view of a piercing pin.
Fig. 3 is a more detailed and larger scale view of a fastening assembly of the invention in a section along a line III-III in fig. 1.
Fig. 4 is a view similar to fig. 3 but showing a fastening assembly according to a second embodiment of the invention.

A perforating unit comprises one or several piercing discs 1 and a padded disc 2, which are rotating with their peripheral surfaces touching or spaced a little from each other. A paper web 5 to be perforated is run between discs 1 and 2. The rim of disc 1 is provided with holes 7, in which are inserted piercing pins 3 clamped in position by means of retainer rods 6 driven into holes 8 which are perpendicular to the plane of disc 1. The rim of padded disc 2 is provided with holes 4, whose mutual distance matches that of piercing pins 3. The edges of pad holes 4 is provided with a dense toothing and the corresponding toothing pattern is cut in the edge of a punching head 13 as soon as discs 1 and 2 do their first rotation. The edge of pad hole 4 is made of a hard, wear-resistant material while said punching head 13 of piercing pin 3 is made of a relatively soft material. As shown in fig. 2, said piercing pin 3 is provided with a reduced portion 10. When piercing pin 3 is properly positioned in a hole 7 in disc 1, said reduced portion 10 will be registered with retainer rod 6.
The retainer rod 6 is provided with a recess 11 and an associated wedge surface 12, the latter rising from recess 11 towards the inner end of rod 6. A spring 9 acting against the inner end of rod 6 urges said rod 6 outwards, whereby said wedge surface 12 is keyed against the bottom of recess 10. Thus, the piercing pin 3 is locked in position. When an inward push is applied to the projecting end of retainer rod 6, said recess 11 shifts into alignment with pin 3 and said pin 3 can be pulled out of its hole and replaced with a new one.
In the case of fig. 3, disc 1 is provided with two parallel arrays of piercing pins 3. The holes 8 intended for retainer rods 6 of adjacent piercing pins 3 unite to form a hole extending through piercing disc 1. Thus, between rods 6 it is possible to employ a single common power unit. The present embodiment comprises two springs 9 as an extension of each other. When used alone, the same springs 9 are suitable for a single-array piercing disc.
The embodiment shown in fig. 4 differs from the preceding one in that the wedge surface 12 is designed as a conical surface and said recess 11 is annular. The bottom of the reduced portion of piercing pin 3 consists of flat surfaces 10ʹ, which decline in a wedge-like fashion towards each other when proceeding to wards the punching head of a piercing pin (upwards in fig. 4). Thus, the piercing pin 3 is also keyed downwards against the bottom of hole 7.
The inner end of retainer rod 6 is fitted with a sealing ring 14. A cylinder space 8ʹ is supplied with hydraulic fluid through a conduit 15. The hydraulic pressure urges rod 6 outwards so as to lock piercing pin 3 in position. When the hydraulic pressure is released, said rod 6 can be pushed inwards for the removal and replacement of piercing pin 3. By creating a negative pressure in space 8ʹ, all retainer rodes 6 can be pulled inwards automatically and simultaneously for the replacement of piercing pins 3.
Preliminary practical tests have shown the surprising observation that the use of a fastening assembly of the invention has substantially reduced the wearing of the punching head cutting edges of piercing pins and thus decreased the need of replacing said piercing pins. This phenomenon is probably due to the fact that the mounting or fastening of piercing pins 3 according to the invention is not absolutely rigid, whereby on each punching stroke said piercing pin is capable of sort of centering its position relative to pad hole 4, so that the shearing forces are uniformly distributed over the entire circumference of a cutting edge.

Claims

1. A fastening assembly for piercing pins in a paper blanks perforating unit, comprising at least two rotating discs, namely a padded disc (2) whose periphery is provided with a circumferential array of holes (4) and a piercing disc (1) whose periphery is fitted with a circumferential array of piercing pins (3) which, as discs (1, 2) are rotating, find their way into holes (4) of padded disc (2) for piercing a paper (5) traveling therebetween, said piercing pins (3) being embedded in radially directed holes (7) in the rim of piercing disc (1) and retained therein by means of retaining members (6) extending transversely to said holes, which is why holes (8) for receiving rod-shaped retaining members (6) are partially united with fastening holes (7) of piercing pins (3) and said piercing pins (3) are provided with a reduced portion (10) at said junction of holes (7, 8), characterized in that said retainer rod (6) is provided with a recess (11), whereby a piercing pin can be replaced when the deepest point of said recess is in register with piercing pin (3), said recess (11) being accompanied by a wedge surface (12) rising from recess (11) towards the inner end of retainer rod (6), a power unit (9, 15) being adapted to act on said inner end for pressing said wedge surface (12) against the wedge-shaped or conical surface of a piercing pin's reduced portion (10).

2. A fastening assembly as set forth in claim 1, characterized in that the rim of piercing disc (1) is provided with two adjacent arrays of piercing pins and said holes (8) intended for retainer rods (6) of adjacent piercing pins join to form holes or passages extending through piercing disc (1).

3. A fastening assembly as set forth in claim 2, characterized in that between the ends of axially aligned retainer rods (6) there is fitted a common power unit (9), adapted to urge retainer rods (6) away from each other.

4. A fastening assembly as set forth in any of claims 1 - 3, characterized in that the power unit is a spring (9) and the outer end of retainer rod (6) projects from the side of piercing disc (1) whereby, when retainer rod (6) is pressed against the load of spring (9), said recess (11) can be shifted into alignment with piercing pin (3) for the replacement of said piercing pin (3).

5. A fastening assembly as set forth in any of claims 1 - 3, characterized in that the power unit comprises pressurized fluid, whereby retainer rods (6) can be shifted into the release position of piercing pins (3) by depressurization or by creating a negative pressure.

6. A fastening assembly as set forth in any of claims 1 - 5, characterized in that the bottom of the reduced portion (10) of piercing pin (3) consists of flat surfaces (10ʹ).

7. A fastening assembly as set forth in claim 6, characterized in that said wedge surface (12) of retainer rod (6) is a conical surface.

8. A fastening assembly as set forth in claim 6, characterized in that said flat surfaces (10ʹ) forming the bottom of the reduced portion (10) of piercing pin (3) are in a wedge-like fashion declined towards each other when proceeding towards the punching head (13) of piercing pin (3).

9. A piercing pin for use in the fastening assembly according to claim 6 or 8, said piercing pin comprising a sharp-edged punching head (13) and a rod portion provided with a reduction, characterized in that the bottom of the reduction (10) of piercing pin (3) consists of flat surfaces (10ʹ).

10. A piercing pin as set forth in claim 9, characterized in that said flat surfaces (10ʹ) forming the bottom of the reduction (10) of piercing pin (3) are in a wedge-like fashion declined towards each other when proceeding towards the punching head (13) of piercing pin (3).