Technical Field

The invention relates to an apparatus for mounting a strengthening material on a sheet of material and punching a hole in both the strengthening material and the sheet of material, comprising a mechanism for feeding the strength¬ ening material which is coiled on a supply spool mounted in the apparatus and a number of punching tools actuated by a lever arm for mounting the strengthening material on the sheet of material and punching the hole and cutting means mounted in connection with the punching tools for cutting off the strengthening m'aterial.

Background Art

An apparatus of the above kind is known, which apparatus provides a strengthened area around two at an interval provided holes. In this known apparatus the strengthening material is fed from two separate supply spools below each tool in a direction which substantially is at right angles to the connecting line of the two tools. This appa¬ ratus shows the drawback that two supply spools on the apparatus have to be replaced when the strengthening ma¬ terial wound on the supply spools has been used. Further¬ more is it by means of the apparatus only possible to provide rectangular strengthening areas around the provided holes which from an appearance view is not fully satis¬ factory.

Description of the Invention

The object of the invention is to provede an apparatus of the above kind by means of which it is possible to provide annular strengthening areas around the provided holes and

in which the s trengthening material is fed from one s ingle supply spool .

The apparatus according to the invention is characterised in that at least two punching tools are supplied with strengthening material from the same supply spool and that each punching tool comprises a patrix and a matrix, said patrix comprising an inner piston actuated by the lever arm for punching the hole and an outer piston guided in a guide plate for punching a roundel of the strengthen- ing material, in which outer piston the inner piston is slidably mounted, and said matrix comprising an upper die block formed to punch the roundel of the strengthening material cooperatively with the outer piston, which strengthening material is fed between the upper die block and the guide plate, and to transfer the roundel to the surface of the sheet of material, and that the matrix furthermore comprises a lower die block mounted at a dis¬ tance below the upper die block and formed to punch the hole in the roundel and the sheet of material cooperatively with the inner piston which sheet of material is placed between the upper die block and the lower die block before activating the apparatus. In this way an apparatus is achieved by means of which a strengthening material, which is supplied from a single supply spool can provide annular strengthening areas around holes also provided by the apparatus.

According to the invention the inner piston can be spring- loaded, preferably by means of cup springs in a direction towards its starting position in which its cutting edge is situated inside the bottom face of the outer piston.

This provides a particularly advantageous and simple con- figuration of the patrix.

Furthermore according to the invention, the strengthening material can be fed a length in connection with each acti-

vating of the apparatus which length is a little longer than the diameter of the punched roundel by means of a feeding mechanism and the part of the strengthening ma¬ terial in which there has been punched roundels is wound onto a wind-up spool also mounted on the apparatus. This provides an appropriate transport of the strengthening material through the apparatus.

Furthermore according to the invention, the strengthening material can be fed parallel to the connecting line of the punching tools.

Furthermore according to the invention, the strengthening material can be led obliguely through the punching tools in relation to the connecting line of the punching tools so that two parallel rows of holes are punched in the strengthening material. In this way the shortest possible fed of the strengthening material between each punching is achieved.

Finally according to the invention the supply spool and the wind-up spool can be mounted in a cassette. This means that the replacement of spent strengthening material can be done very easily.

Brief Description of the Drawing

The invention is explained in the following with reference to the accompanying drawing, in which

Fig. 1 is a first embodiment of the apparatus according to the invention and a cassette with a supply and a wind- up spoole shown from ahead,

Fig. 2 is the same from the top as the housing of the cas¬ sette has been omitted,

Fig. 3 is on a larger scale a sectional view of the appa¬ ratus taken along the line III-III of Fig. 2 as the housing of the cassette has been omitted, and

Fig. 4 is another embodiment of the apparatus according to the invention in the same scale as in Fig. 2 in which the strengthening material is fed obliquely through the apparatus .

Description of the Preferred Embodiments of the Invention

Figs . 1 - 3 show a first embodiment of an apparatus accord- ing to the invention for mounting a strengthening material, eg. a plastic adhesive tape or a similar adhesive band- shaped material on a sheet of material and punching a hole in both the strengthening material and the sheet of material. The apparatus comprises a lower portion 1 and a lever arm 2 pivotally mounted in relation thereto on an axle 3 and adapted to simultaneously actuate two punching tools , 4' .

Each punching tool comprises as it most clearly appears from Fig. 3, a patrix 5 and a matrix 6. The patrix 5 com- prises an inner piston 7 formed to punch the hole and an outer piston 8 formed to punch a roundel of the strength¬ ening material and transfer this to the sheet of material. The inner piston 7 at its upper end communicates with an axle 9 mounted transversely in the lever arm 2, which axle 9 is parallel with the pivot shaft 3. This transverse axle 9 ensures a simultaneous actuating of the two punching tools 4, 4' . The inner piston 7 is guided by the outer piston 8 and preloaded in a direction towards its starting position by means of a spring 10. The outer piston 8 is guided by a guide plate 11 in the lower portion 1 and is preloaded in a direction towards its starting position by means of a spring 12 wound around the pivot shaft 3, as the free ends of said spring 12 engage the lower portion 1

and the lever arm 2, respectively, which lever arm 2 thus is also preloaded in a direction towards its starting position. The preloading of the outer piston 8 in a di¬ rection towards its starting position by means of the 5 preloading of the lever arm 2 is provided by means of a shoulder 15 provided on the inner piston 7 which abuts a surface 16 on the outer piston 8 and a uoke 17 connected to the upper end of the inner piston 7 which yoke 17 sur¬ rounds the transverse axle 9.

10 The matrix 6 comprises an upper die block 19 formed to punch the roundel of the strengthening material coopera¬ tively with the outer piston 8, and a lower die block 19 mounted below the upper die block 18 and formed to punch the hole in the roundel and the sheet of material coopera-

15 tively with the inner piston 7. A collecting chamber 20 for collecting the clippings from the punching is provided below the lower die block 19 in the lower portion 1. The collecting chamber 20 is closed at the bottom by means of a bottom plate 21.

20 The apparatus furthermore comprises a not shown feeding mechanism which feeds the strengthening material a length which is a little longer than the diameter of the punched roundel at each activating of the apparatus, i.e. of the lever arm 2. The strengthening material is, as it is most

25 clearly shown in Fig. 2, wound on a supply spool 22 and led through the punching tools 4, 4' between the guide plate 11 and the upper die block 18 whereafter it is led to a wind-up spool 23 upon which it, as the apparatus is activated and holes are being punched, is wound. It is

30 furthermore suggested in Fig. 2 that the supply spool 22 and the wind-up spool 23 can be mounted in a cassette 24 which is inserted into the apparatus. This is shown with a dot-and-dash line in Fig. 1. As it appears from Fig. 1, the strengthening material is fed through the apparatus

35 parallel to the connecting line of the two punching tools

(4, 4'). This feed entails that the length L of feed of the strengthening material between each punching of roundel and hole is chosen so that no roundel is punched at the same place of the strengthening material by the two suc¬ cessive punching tools 4, 4' . In order to avoid this when the apparatus comprises two punching tools, the length of feed can be calculated according the formula

2a

2 η + 1

wherein a - the distance between the centres of the punching tools, and η — the number of holes between holes punched in the same punching.

When using the formula, the diameter of the punched roundels naturally must be considered when determining η .

As an alternative to feeding the strengthening material through the apparatus parallel to the connecting line of the punching tools (4, 4'), the strengthening material can be fed obliguely through the apparatus, as shown in Fig. 4. In this way the length of feed between two punch- ings is reduced as two parallel rows of roundels are punch¬ ed in the strengthening material.

The appartus during use functions in the following way. The sheet of material is placed in the apparatus between the upper die block 18 and the lower die block 19 where¬ after the lever arm 2 is activated. In the first part of the travel of the lever arm 2, the feeding mechanism not shown will feed the strengthening material a length so that unused strengthening material is situated under both tools. This feed of the strengthening material is completed before the bottom face 25 of the outer piston 8 moves past the sub base 26 of the guide plate 11 when the lever

7 arm 2 is further activated. The bottom face 25 of the outer piston 8 hereafter conctacts the strengthening material and cooperatively with the upper die block 18 punches a roundel which is then pressed towards and mounted on the sheet of 5 material by the outer piston 8 as the bottom face 25 of the outer piston 8 presses against the lower die block 19. By a further pressing of the lever arm 2, the cutting edge 27 of the inner piston 7 passes the bottom face 25 of the outer piston 8 and travels into the lower die block 10 19 whereby the hole is punched and the clipping falls into the collecting chamber 20. Then the lever arm 2 is let go and this and the inner piston 7 and the outer piston 8 will return to their starting position because of their spring preloading by means of the springs 10 and 12.