FI78637C - STICKTAPPARS FAESTANORDNING FOER EN PAPPERSBLANKETTERS PERFORERINGSENHET. - Google Patents

Description

1 78637

Pin attachment device for paper form punching unit. - Sticktappars fästanordning för en pappersblan-ketters perforeringsenhet.

The invention relates to a pin fixing device for a paper form perforating unit comprising at least two rotating discs, namely a cushion disc with a circumferential row of circumferential holes and a discs with a circumferential row of dowel pins attached to the circumference of the coulter the dowel pins being embedded in radial holes in the circumference of the dowel disc, where they are retained by retaining members transverse to the holes, for which the receiving holes of the pin-like retaining members partially coincide with the mounting holes of the dowel pins and the dowel pins have a thinning at said holes.

Such perforating units are used in printing and laminating machines that produce paper forms with rows of holes for tractor printing of computer printers.

In known perforating units (U.S. Pat. No. 4,434,690), the pin pins are fixed to the pin disc with hexagon socket screws which are tightened against the side surface of the pin pin by turning with a wrench. The piercing pin of the dowel pin must be of a relatively soft material, since a small-pointed star pattern is formed on its cutting edge by means of a hole in the cushion part. This is done by rotating the needle disc and pad disc once after the new needle pins are installed. The edges of the hole in the cushion part, on the other hand, are made of hard, wear-resistant material.

The cutting edges of the dowel pin wear out and become dull quickly, with the result that all the dowel pins on the dowel disc must be replaced at least every few days. One perforation unit may have, for example, four pin rings, each of which may have almost one hundred pin pins. As a result, the daily working time for changing the plug-pins can be as much as 2,78637 pa two hours, during which time the entire production machine has to stand still.

In order to speed up the replacement of the pins, it has been proposed (U.S. Pat. No. 4,604,931) to use a spring-loaded detent pin with a rounded end for thinning the pin. Here a compromise has had to be made between the fastening strength of the pin and the ease of replacement, as the pin must be forcibly removed with a tool against the holding force. However, the retained force must be large enough so that the plug pins do not come loose after fastening in the first round, so that the plug pins are subjected to a large tearing force when the edge cover of the plug ends is cut with a cushion disc. The retaining force must be large enough to prevent the pin from rotating during use. If these requirements are met, the clamping force of the retaining pin becomes so great that it is not possible to replace the retaining pins without difficulty. If the replacement is done by removing the common base plate of the retaining pin springs, the retaining pins must also be removed and replaced after inserting the retaining pins. After this, the base plate must be tightened in place with a fairly large force. In practice, there is always a certain risk of damage to such a spring fastening, in which the plug pins can be removed by pulling. As a result of higher speeds and centrifugal forces, the pin may detach and fly out of the pin disc.

The object of the invention is to provide a plug fastening device of the type mentioned at the beginning, which enables quick change of plug pins and secure fastening.

This object is achieved on the basis of the features of the invention set out in the appended claims.

In the following, some embodiments of the invention will be described in more detail with reference to the accompanying drawings, in which Fig. 3 78637 shows a side view of the circumferential parts cooperating with a needle disc and a pad disc.

Figure la shows on a larger scale a piercing pin as seen Lavis-tinpään side of the arrow a in Figure 1 Ά direction.

Figure 2 shows a side view of the plug.

Figure 3 shows in more detail and on an enlarged scale a section of the fastening device according to the invention taken along the line III-III in Figure 1.

Fig. 4 shows a fastening device according to a second embodiment of the invention in a manner corresponding to Fig. 3.

The perforating unit comprises one or more plug discs 1 and a pad disc 2, which rotate the circumferential surfaces against each other or at a small distance from each other. The tearable paper web 5 is guided between the discs 1 and 2. Insertion pins 3 are placed in the holes 7 in the circumference of the disc 1, which are locked in place by retaining pins 6 inserted in the holes 8 perpendicular to the plane of the disc 1. The cushion disc 2 has holes 4 with a distance corresponding to the distance of the insertion pins 3. The edges of the pad holes 4 have dense toothing, the corresponding tooth pattern of which intersects the edge of the insertion head 13 when the discs 1 and 2 rotate for the first time. The edge of the pad hole 4 is made of a hard, wear-resistant material, while the plug end 13 of the plug pin 3 is of a relatively soft material. As shown in Fig. 2, a thinning 10 is made in the pin 3. When the pin 3 is inserted in the hole 7 of the disc 1, the thinning 10 hits the retaining pin 6.

The retaining pin 6 has a recess 11 with a wedge surface 12 which rises from the recess 11 towards the inner end of the pin 6. A spring 9 resting on the inner end of the pin 6 pushes the pin 6 outwards, whereby the wedge surface 12 wedges against the bottom of the recess 10. In this case, the plug 3 locks in place. When the retaining pin 6

Claims (10)

A pin attachment device for a paper form punching unit comprising at least two rotating discs, namely a pad disc (2) having a circumferential row of circumferential holes (4) and a disc disc (1) having a circumferential row of pin pins (3) attached thereto. which, as the discs (lr 2) rotate, hit the holes (4) of the cushion disc (2) by piercing the intermediate paper (5), the plug pins (3) being embedded in the radial holes (7) r in the circumference of the plug disc (1) where they are retained transverse to the holes retaining members (6) for which the receiving holes (8) of the pin-like retaining members (6) partially coincide with the mounting holes (7) of the plug pins (3) and the pin pins (3) have a thinning (10) at said junction of the holes (7, 8) the retaining pin (6) has a recess (11), the deepest point of which is located at the pointing pin (3), the pointing pin is replaceable, and the recess (11) is associated with a wedge surface (12) which rises towards the inner end of the retaining pin (6), on which the power device (9, 15) is arranged to act to press the wedge surface (12) against the wedge-shaped or conical surface of the thinned part (10) of the pin. Fastening device according to Claim 1, characterized in that the circumference of the plug disc (1) has two adjacent rows of plug pins and the holes (8) for the retaining pins (6) of the adjacent plug pins merge into through holes in the plug disc (1). Fastening device according to Claim 2, characterized in that there is a common force device (9) between the ends of the axially co-located retaining pins (6), which is arranged to push the retaining pins (6) away from one another. Fastening device according to one of Claims 1 to 3, characterized in that the power device is a spring (9) 6 78637 and the outer end of the retaining pin (6) protrudes from the side of the connecting disc (1), pushing the retaining pin (6) against the force of the spring (9). 6) the recess (11) is movable at the plug (3) for replacement of the plug (3). 4 78637 of the end is pushed inwards, the recess 11 moves to the pin 3, whereby the pin 3 can be pulled out of its hole and replaced with a new one. In the case of Figure 3, the disc 1 has two parallel rows of pin pins. The holes 8 for the retaining pins 6 of the adjacent plug pins 3 coincide with the through hole of the plug disc 1. In this case, one common power unit can be used between the pins 6. In the case shown, the two springs 9 are set as an extension of each other. The same springs 9 used alone are suitable for a single-row plug disc. The embodiment of Figure 4 differs from the previous one in that the wedge surface 12 is formed as a conical surface and the recess 11 is annular. The bottom of the thinning of the pin 3 is formed by planar surfaces 10 'which wedge wedge towards each other as they move the piercing end of the pin (in Fig. 4 upwards). In this case, the plug pin 3 also wedges downwards against the bottom of the hole 7. The inner end of the retaining pin 6 is provided with a sealing ring 14. Hydraulic fluid is introduced into the cylinder space 8 'through the channel 15. The fluid pressure pushes the pin 6 outwards, locking the plug-pin 3 in place. When the liquid pressure is removed, the pin 6 can be pushed inwards to release and replace the plug pin 3. By creating a vacuum in the space 8 ', all the retaining pins 6 can be pulled in automatically and simultaneously, whereby the retaining pins 3 can be replaced. In the preliminary practical tests, the surprising finding has been made that when using the fastening device according to the invention, the wear of the cutting edges of the piercing ends of the puncture pins is also substantially reduced and the need to replace the pins is thus reduced. This phenomenon is probably due to the fact that the fastening of the pins 3 according to the invention is not completely rigid, whereby with each punching stroke the pin can find its position with respect to the pad hole 4 so that the cutting forces are evenly distributed over the entire circumference of the cutting edge. 5,78637 Fastening device according to one of Claims 1 to 3, characterized in that the power unit is a pressurized medium, in which the retaining pins (6) can be moved to the disengagement position of the plug pins (3) by relieving the pressure or creating a vacuum. Fastening device according to one of Claims 1 to 5, characterized in that the base of the thinner (10) of the plug (3) is formed by planar surfaces (10 '). Fastening device according to Claim 6, characterized in that the wedge surface (12) of the retaining pin (6) is a conical surface. Fastening device according to Claim 6, characterized in that the planar surfaces (10 ') forming the bottom of the thinning (10) of the plug (3) extend wedge-like towards each other as they move towards the punch (13) of the plug (3). Plug for use in a fastening device according to claim 6 or 8, the plug comprising a blade-edged plug head (13) and a shank part with a thinner, characterized in that the bottom of the thinner (10) of the plug (3) consists of planar surfaces (10 '). Pin according to Claim 9, characterized in that the planar surfaces (10 ') forming the bottom of the thinning (10) of the pin (3) extend wedge-like towards each other as they move towards the puncture pin (13) of the pin (3).