EP1604751B1 - Punching device and punch therefor - Google Patents

Description

The invention relates to a stamping device and its punch according to the preamble of claim 1 (see for example EP-A-1 005 963). In particular, the invention relates to a punching device and a punch for unfired planar ceramic substrates, in particular so-called green sheets.

As a rule, green sheets must be provided with a number of small holes during their production, which later serve, for example, for the through-connection of conductors which are applied to the ceramic substrates. These are relatively small holes of significantly less than a millimeter in diameter, such holes are to be attached in large numbers. The punching device has a corresponding large number of punches on. The punches are provided with heads which are held in a holding device, for example a holding plate, in order to be moved up and down with it in the longitudinal direction of the shank, ie for example.

A similar punching device is known, for example, from EP 0 354 152 B1. The punches are moved here by magnetic drives. These punches are each provided with a head which is attached to the elongated shaft of the punch.

The punches are exposed in their activity a high abrasive load. They must therefore be made of a suitably wear-resistant hard material. They are therefore formed from an elongated needle-like body to which the usually made of other material head is recognized later to approach the top plate or other drives.

As known for example from US Pat. No. 3,974,728, the working part of a punch can also be inserted into a headed body and fastened to it by adhesive, for example. However, this requires a relatively complex production. After punch punches are to be regarded as wear parts, it is therefore desirable to be able to produce these as quickly as possible, simple and inexpensive, the quality must not suffer any loss. However, the quality is significantly determined by the straightness, ie the precision of the punch. Splices between a cylindrical drive body and a cylindrical working part are critical here.

From US-PS 4,700,601 it is also known to provide punches intended for punching paper with a plastic head. For this purpose, the punch made of metal has an annular groove. The area provided with the annular groove is then encapsulated with a cylindrical plastic body, wherein the plastic partially flows into the annular groove and thus produces a positive connection between the head and the punch.

The stamps for green sheets can not usually be provided with artificial heads. Due to the small diameter of the shanks of the punches are usually no sufficient permanent positive connections between a plastic head and the punch.

On this basis, it is an object of the invention to provide a punch for a green-sheet punching device and a corresponding punching device, the punch to be simple and inexpensive to manufacture and thereby meet high quality standards.

This object is achieved with the punch of claim 1 and the punching device according to claim 20:

The punch according to the invention has a punch shaft which has a head at one end and a working part at the opposite end. At the head of the stamp shaft is provided on its lateral surface with at least one recess. In the region of the recess sits an annular head, the one in the recess and cross The head thereby positively locking on the shaft locking projection. This projection is created by plastic deformation of the head. This usually has the consequence that the material of the head rests against the shaft under a certain bias. This is especially true when the head is made of a suitable metal such as steel, brass or aluminum. Unlike a Kunststoffumspritzung, which can be solved as a result of natural shrinkage or shrinkage of the plastic something, a tight fit is secured here.

The production of the punch is possible with very short cycle times. It is only necessary to push a head blank over the shaft and then secure it to the shaft by means of a suitable deformation method for plastically deforming the head. The production methods with which this can be realized, for example, embossing, pressing, rolling, hammering or other methods for chipless shaping. If the head is made of a low-melting metal, it could if necessary also be produced in a casting process, for example in a die-casting process. However, this is considered less advantageous because the overhead involved is higher.

As mentioned, the projection securing the head to the shaft is preferably produced by plastic deformation of the head blank. For this purpose, a depression is formed on the head during manufacture. Preferably, the shape of the recess corresponds to the shape of the recess provided on the shaft. If this is, for example, an annular bead, an annular recess is preferably formed on the otherwise cylindrical outer peripheral surface of the head. This will the required plastic deformation of the head is kept to a minimum. However, it is also possible to supplementarily form an antagonistic or deforming pressure, for example in the axial direction on the head, in order to promote the radially inwardly directed inflow of the head material into the recess of the shaft.

The recess of the shaft preferably has a waisted shape. Sharp edges are avoided in order not to favor breaking off of the slender shaft in the region of the recess. Preferably, the recess is bounded by an annular concavely curved annular surface, which is formed without edges and without heels. The recess then has an adapted shape.

The head is preferably located at the end of the shaft, which is opposite the working part. He preferably sits at the end of the shaft, so that the shaft end terminates with the head or slightly protrudes from the head. It has proven to be advantageous to arrange the recess and corresponding to the recess in the recess projection of the head close to the shaft end. Thus, the passage of the head on the side remote from the shaft end has a cylindrical guide section which transmits or supports tilting moments acting on the head to the shaft, without stressing the zone of the shaft weakened by the recess. This is especially true when the recess of the shaft, as is preferably the case, at the upper, the shaft end facing the plan surface of the head closes.

The head preferably has, prior to its plastic deformation, a through-hole whose width is slightly greater than that of the shaft, so that the shaft can be inserted into the head with little play. After the plastic deformation of the head sits on the shaft without play. Preferably, the through hole of the head has been narrowed to the full length so far that the head sits gap-free on the shaft.

In addition to the positive locking of the head on the shaft, a cohesive connection can be provided. This can be, for example, an adhesive connection. The advantage of this measure is, for example, the easy introduction of the adhesive, which can be accommodated in the recess of the shaft before the plastic deformation process.

It is also possible that the adhesive for positive locking of the head on the shaft after the plastic deformation of the head is introduced by pulling by capillary action after application between the shaft and head.

Notwithstanding the embodiments described above, a plurality of recesses may be provided instead of a recess, in which case the above statements apply accordingly. The recesses may extend around the entire circumference of the shaft or only over part of it, and may be axially spaced or at the same height.

Further advantageous details of embodiments of the invention are the subject of the drawing, the description and / or claims.

Figur 1

eine Stanzeinrichtung für Green Sheets in einer schematisierten perspektivischen Prinzipdarstellung,

Figur 2

die Stanzeinrichtung nach Figur 1 in einer längs geschnittenen ausschnittsweisen schematisierten Darstellung,

Figur 3

einen Stempel vor Befestigung seines Kopfs an seinem Schaft in längs geschnittener Prinzipdarstellung,

Figur 4

den Stempel mit fest auf seinem Schaft sitzenden Kopf,

Figur 5 und 6

einen Stempel jeweils vor und nach der Befestigung seines Kopfs auf dem Schaft in einer alternativen Ausführungsform in längs geschnittener Darstellung,

Figur 7 und 8

einen Stempel jeweils vor und nach der Befestigung seines Kopfs auf dem Schaft in einer alternativen weiteren Ausführungsform in längs geschnittener Darstellung und

Figur 9 und 10

einen Stanzstempel jeweils vor und nach der Befestigung seines Kopfs auf dem Schaft in einer alternativen fortentwickelten Ausführungsform in längs geschnittener Darstellung.

In the drawings, embodiments of the invention are illustrated. Show it:

FIG. 1

a punching device for green sheets in a schematic perspective schematic representation,

FIG. 2

1 shows the punching device according to FIG. 1 in a longitudinal sectioned schematized representation,

FIG. 3

a stamp before attachment of his head to his shaft in longitudinally cut schematic diagram,

FIG. 4

the stamp with his head firmly seated on his shaft,

FIGS. 5 and 6

a punch in each case before and after the attachment of its head on the shaft in an alternative embodiment in longitudinal section,

FIGS. 7 and 8

a punch in each case before and after the attachment of his head on the shaft in an alternative further embodiment in longitudinal sectional view and

FIGS. 9 and 10

a punch in each case before and after the attachment of his head on the shaft in an alternative developed embodiment in longitudinal section.

FIG. 1 illustrates a stamping tool 1 to which a lower tool 2 and an upper tool 3 belong. The upper tool 3 is by means of two guides 4, 5 on the lower tool 2 back and away linearly reciprocally movable. The lower tool 2 includes a support plate or receiving device 6, in which punched holes 7 are formed. The punching holes 7 are numerous in the support plate 6 and formed at those locations where holes are to be punched in a laid on the support plate 6 Green Sheet (unfired ceramic substrate). For this purpose, stamps 8 are arranged on the upper tool 3, which point towards the lower tool 2 and end above the support plate 6. The punches 8 can dip into the punch holes 7 as they are moved down. Above the platen 6 is a hold-down plate 9 is arranged to guide the punch 8 and to hold down the lying on the platen green sheet 9, which has been left in Figure 1 away to give the view of the punch 8 and the receiving device 6 free.

The upper tool 3 together with hold-down plate 9 are shown in FIG. The hold-down plate 9 is arranged vertically above the support plate 6 independently of the punching movement of the punch 8 and defines with this a gap 11 for receiving a green sheet, not shown. The hold-down plate 9 is connected to the upper tool 3 or part thereof and movable therewith. An arrow 12 indicates the direction of movement of the upper tool 3.

The punch 8 is axially guided in the hold-down plate 9 by at least one guide bush 13 and possibly another provided on the hold-down plate 9 guide bushing 14. In this case, the punch 8 preferably has a multi-stepped profile and a slim working part 15 at its lower part projecting into the guide bush 14. This is associated with the punched hole 7, which is formed in a sleeve 16 held on the receiving device 6.

The punch 8 is held axially immovable in an upper holding device 17, which serves to give the punch 8 its axial movement. The holding device 17 belongs to the upper tool 3. It can basically be designed in different ways. It is essential that it has a drive element 18, which is formed in the present embodiment as a plate and serves to move the punch 8 down. Next to the holding device 17 includes a return element 19, which is formed in the present embodiment as a plate and serves to the punch 8 against its punching direction, i. to move away from the receiving device 6 away. The plates forming the drive element 18 and the return element 19 can, as shown, be fixedly attached to one another or else movable relative to one another. They can be stretched by spring means against each other and clamp the punch 8 between each other. It may also not illustrated spring means between the punch 8 and the holding device 17 may be provided.

The punch 8 has at least one preferably cylindrical elongated shaft 21 and a preferably also substantially cylindrical head 22, which are positively connected with each other. In this case, the shaft 21 and the head 22 are preferably made of different metals. The shaft 21 is in terms of its Stan properties optimized. In particular, at his working part 15 us he is subject to considerable wear, especially in the field of cutting edges. This is countered by a suitable choice of materials. The shaft 21 is thus made of a suitable steel. The head 22, however, serves only to initiate the required driving forces in the punch 8. Oversized hardness or wear resistance is not important. It is thus formed as a separate part of a suitable metal, such as a good deformable steel or other metals, and attached to the shaft 21. This is illustrated in detail in FIGS. 3 and 4. The shaft 21 has for attachment of the head 22 has a recess 23, for example in the form of a shank 21 surrounding flat annular bead. This has, as Figure 3 illustrates, a waisted shape. The limiting annular surface 24 is formed without edges and without heels. The axial length of the annular surface 24 exceeds the depth of the recess 23 by far. The axial length of the annular surface 24 also exceeds the largest diameter of the annular surface 24 by far. Further, it has been found to be advantageous if the axial length also exceeds the circumference of the annular surface 24, as it is to be measured at the point with the smallest diameter of the annular surface 24.

The head 22 is formed from an initially hollow cylindrical blank 22 ', which has a central through-bore 25. The diameter of the through hole is preferably slightly larger than the shaft diameter, so that the blank 22 'can be pushed over the shaft 21 without difficulty. To fix the blank 22 'to the shaft 21 and thus to form the head 22, the blank 22' is deformed. This can be seen by comparing Figures 3 and 4. The head 22 is provided with a cylindrical recess 26 on its round circumferential recess 27, which is caused by a radially inwardly directed compression of the head 22. The recess 27 preferably corresponds in shape to the shape of the recess 23. The material of the head 22 flows into the recess 23 to form a radially inwardly directed rib-like projection 28. The head 22 thus lies flat against the annular surface 24, in particular in the region of the recess 23. In addition, the head 22 may be compressed radially inwardly in its remaining area, so that its through hole 25 rests without gaps and preferably with a certain bias on the shaft 21. The head 22 thus has an upper plane surface 29 serving for introducing force, a lower plane surface 31, which likewise serves to introduce force, and a cylindrical outer surface 26 which adjoins the lower plane surface 31 facing the working part 15 of the shaft 21. On the other hand, the recess 27 preferably adjoins the plane surface 29. Further preferably, the head 22 is arranged so that the plane surface 29 is substantially aligned with an upper edge 32, in which the cylindrical shaft 21 merges into the curved annular surface 24. On the other hand, the other edge 33, at which the annular surface 24 ends, preferably at about the middle height of the head 22nd

The presented configuration has the advantage that the head 22 can be attached to the shaft 21 in an axially desired and selected position. The precision of the position of the recess 23 does not matter. The position of the head 22 is set at the moment of crimping the head 22. Other manufacturing tolerances play no or only a very minor role. It can be thus easily produce punch 8 in high quality. In addition, very different embodiments can be produced in the simplest way, for example by combining differently shaped heads 22 with shafts 21 of one and the same type. Different axial head lengths or head diameters or head materials can be used. In addition, the heads 22 in different axial positions, in which the recess 23 is located within the through hole 25, are fixed. Furthermore, it is possible to attach the recesses 23 at different shaft positions. This is especially true when the recesses 23 are produced in a machining process, for example by grinding.

The stamping punch 8 described so far operates in the punching tool 1 as follows:

As illustrated in FIG. 2, the upper tool 3 is reciprocated in the direction of the arrow 12. The head 22 is held between the drive member 18 and the return member 19. Both attack on the flat surfaces 29, 31 of the head 22. The power transmission between the head 22 and the shaft 21 takes place by positive engagement between the projection 28 and the recess 23 (Figure 4). The power transmission is flat and uses the entire ring surface 24. It therefore comes neither to local stress peaks, nor shear effects. Even with fast work, the heads 22 do not detach from the punches 8. This is an essential advantage resulting from the fact that the projection 28 and the recess 23 are identical in shape or, strictly speaking, have completely complementary shapes to each other.

For the punch 8 according to FIGS. 5 and 6, the above statements apply correspondingly, with the following exceptions:

The recess 23 does not extend around the entire circumference of the shaft 21 but only over a part thereof. It can be presented as a rounded, for example, a cylindrical lateral surface notch following. Optionally, on the opposite side and at the same height or, as shown, axially offset, a further recess 35 may be provided which has a same or a modified shape. Accordingly, after deformation of the blank 22 ', the head 22 has a first upper recess 27 in the region of the upper recess 23 and a recess 36 in the region of the lower recess 35. The recesses 27, 36 are formed by radial compression and deformation of the blank 22 'and form dents or indentations in the lateral surface 26.

As FIGS. 7 and 8 illustrate, the head 22 may also extend upwards beyond the recess 23, so that the upper planar surface 29 is at an axial distance from the edge 32. Preferably, however, remains between the lower end face 31 of the head 22 and the lower edge 33 of the shaft 21, an axial distance which is at least as large as the axial length of the recess 23 and which is substantially greater than the diameter of the shaft 21. Thereby the head 22 held tilt-proof on the shaft 21.

Figures 9 and 10 illustrate a modified embodiment of the punch 8, in which the head 22 in addition is secured to the shank 21 cohesively for positive locking. In order to produce the connection, a suitable connecting means, for example an adhesive hardening by pressure or heat or intimate metal contact 37, is arranged in the recess 23. This is not stripped when gluing the blank 22 'and thus remains as a depot in the recess 23. In the subsequent plastic deformation of the blank 22' and the formation of the projection 28, which penetrates into the recess 23, the adhesive 37 is largely displaced, wherein it penetrates on both sides of the recess 23 in the gap formed between the head 22 and the shaft 21 and fills this to form a glued joint 38. The adhesive 27 may subsequently cure over time. In addition, it can be made to harden by heat. It is also possible to use adhesives which harden as soon as the glue joint falls below a minimum width, as is the case with some instant adhesives.

The punch according to the invention has a positively held head 22. The head 22 is held on the shaft 21 of the punch 8 by displacing material radially inward by plastic deformation, for example by radial application of pressure, so that a projection 28 is formed which rests flat against the wall of a recess 23. It ensures a safe and lasting power transfer.

LIST OF REFERENCE NUMBERS

1

punching tool

2

lower tool

3

upper tool

4, 5

guides

6

recording device

7

punch holes

8th

stamp

9

Down plate

11

gap

12

arrow

13, 14

guide bush

15

working part

16

Rifle

17

holder

18

driving element

19

return element

21

shaft

22

head

22 '

blank

23

recess

24

ring surface

25

Through Hole

26

lateral surface

27

deepening

28

head Start

29, 31

plane surfaces

32, 33

edge

35

recess

36

deepening

37

adhesive

38

bonded joint

Claims (20)

1. Punch (8) for a green-sheet die cutting system (1) with a shank (21) and a ring-shaped head (22), characterised in that the shank (21) is provided with at least one recess (23) at one end, and that the ring-shaped head (22) has a projection (28), which engages into the recess (23) and thus positively secures the head (22) to the shank (21) and which is generated by plastic deformation.
2. Punch according to Claim 1, characterised in that on the outer peripheral face (26) of the head (22) the projection (28) has an associated depression (27) configured during the production of the projection (28).
3. Punch according to Claim 1, characterised in that the recess (23) is an annular crimp.
4. Punch according to Claim 1, characterised in that several recesses (27, 35) arranged in a ring-shaped region of the shank (21) are configured thereon.
5. Punch according to Claim 1, characterised in that the recess (23) has a necked shape.
6. Punch according to Claim 1, characterised in that the recess (23) is defined by a ring-shaped concavely arched ring face (24).
7. Punch according to Claim 6, characterised in that the ring face (24) is configured without edges and shoulders.
8. Punch according to one of Claims 2 to 7, characterised in that the depression (27) has a shape adapted to the recess (23).
9. Punch according to one of Claims 2 to 7, characterised in that the depression (27) is formed in a non-cutting shaping process.
10. Punch according to one of Claims 2 to 7, characterised in that the recess (23) is arranged completely inside the head (22).
11. Punch according to Claim 1, characterised in that the head (22) is substantially cylindrical.
12. Punch according to Claim 1, characterised in that the head (22) has at least one substantially plane face (29, 31).
13. Punch according to Claim 12, characterised in that the face (29) adjoins the recess (23).
14. Punch according to Claim 1, characterised in that the head (22) has a continuous bore (25), which during assembly of the head (22) on the shank (21) was reduced in width by plastic deformation of the head (22) to such an extent that the shank (21) is held without play in the continuous bore (25) on the entire axial length of the head (22).
15. Punch according to Claim 1, characterised in that the head (22) has a continuous bore (25), which during assembly of the head (22) on the shank (21) was reduced in width by plastic deformation of the head (22) to such an extent that the shank (21) is held without gaps in the continuous bore (25) on the entire axial length of the head (22).
16. Punch according to Claim 1, characterised in that the head (22) is made of a metal.
17. Punch according to Claim 1, characterised in that the plastically deformed head (22) is positively and additionally integrally secured to the shank (21).
18. Punch according to Claim 17, characterised in that a deposit of adhesive (37) arranged in the recess (23) of the shank (21) before the plastic deformation of the head (22) serves to integrally secure the head (22).
19. Punch according to Claim 17, characterised in that adhesive (37) arranged in the recess (23) of the shank (21) after the plastic deformation of the head (22) serves to integrally secure the head (22).
20. Die cutting system (1) with a punch (8) according to one of the preceding claims.

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