EP0077932A1

EP0077932A1 - Apparatus for making a riveted joint of metal sheets

Info

Publication number: EP0077932A1
Application number: EP82109043A
Authority: EP
Inventors: Gerd-Jürgen Eckold; Hans Maass
Original assignee: Walter Eckold & Co KG Vorrichtungs- und Geratebau GmbH
Current assignee: Walter Eckold & Co KG Vorrichtungs- und Geratebau GmbH
Priority date: 1981-10-28
Filing date: 1982-09-30
Publication date: 1983-05-04
Also published as: ES279143Y; HK82486A; US4614017A; ES276168Y; CA1182665A; ES276168U; CA1182665A1; SU1160925A3; ES279143U; SG24986G; EP0077932B1; DE3261709D1

Abstract

In a device for rivet-like joining of sheets by pushing through material and its extrusion behind the incision edges, the countercuts of the die, which cooperates with the cutting punch (12) and have an anvil (14) set back behind these countercuts, are clamped on one side by free end edges, leaf springs (16) extending parallel to the cutting punch or male movement. The leaf springs can have different longitudinal contours and cross-sectional shapes; they can taper towards the end and can be designed in one or more parts in a different geometric arrangement. A chip collection and removal space can be formed between the anvil (14) and the leaf springs (16). One embodiment sees the multiple arrangement of male-female combinations in an upper or Lower die in front, where appropriate the leaf springs sit on cylindrical bases.

Description

The invention relates to a device for rivet-like connection of sheets with the features mentioned in the preamble of claim 1.
Such a device is known from DE-OS 31 06 313. It has two levers next to the anvil of the die, which have the counter cutting edges. The levers are pivotable about axes extending transversely to the direction of the press stroke, and a helical compression spring acts on the two levers in such a way that they are pretensioned in the cutting position in which they rest on the anvil. The linear distance between the two lever swivel axes is greater than the distance between the two punch cutting edges.
A device of the same type is also known from US Pat. No. 2,288,308. Here, the die comprises a plurality of components: an anvil, which tapers towards the free end, extends from a base; The counter-cutting elements in the form of pierced steel plates are supported on the base on the oblique side surfaces of the anvil. By the bore is guided by a bolt on which spring washers also act on the outside of these plates. - The distance between the plate edges with which they are supported on the base and by which they tilt when evading laterally is therefore greater than the distance between the cutting edges and counter-cutting edges in the cutting position.
The same applies to the embodiment according to US Pat. No. 2,254,558; In the embodiment shown there, the cutter body and the restoring leaf spring are formed in one piece, angled or bent, and the cutter bodies are supported by the anvil.
In the known constructions described it follows that during the cutting of the two sheets onto the components provided with the counter cutting edges - that is to say the levers or plates - an inward force component directed towards the anvil occurs, thereby ensuring that the counter cutting edges during the Do not dodge the cutting phase laterally.
On the other hand, this means that in the second phase of extrusion, the shearbars not only deflect laterally, but also have a component directed towards the punch during their evasive movement, which tends not to make the connection so solid, would be possible as actually under otherwise identical conditions .. in addition, chips from the cutting parts and the supporting parts they can get the anvil, thereby providing the usefulness of the entire device in question. - It would be more desirable that the elements provided with the counter cutting edges would be moved exactly to the side.
This could possibly be achieved constructively by a corresponding slide bearing of the components provided with counter-cutting edges and springs acting perpendicular to the direction of the press stroke. This would not only result in an expensive and complicated structure, but also in an even larger lateral projection of the die than would appear to be unavoidable with the most modern known construction according to the aforementioned DE-OS.
The object of the invention is to provide a device of the same type, in which an optimal connection is created, in which a simple structure also allows inexpensive mass production, and which can finally have minimal dimensions in the direction transverse to the press stroke.
This object is achieved according to the invention in that the countercuts are formed by free end edges of leaf springs clamped on one side and extending parallel to the male movement.
This has the following advantages:
The leaf springs are simple stamped parts, and since they extend parallel to the press stroke, the anvil can also be a simple stamped part made of sheet metal. The leaf springs perform three functions at the same time: they represent the shearbars, they transmit the cutting forces to a base, and they provide the restoring force after lateral evasion. This swiveling takes place around an axis that lies almost exactly under the respective shear bar because the leaf springs used can be relatively thin. It has been shown that the risk of lateral deflection of the counter cutting edges during the cutting phase is quite low even with fairly thin leaf springs. The leaf springs penetrate not only with their counter blades, but - even if only to a very small extent - with their entire surface facing the stamp into the sheet metal facing them and are therefore supported by the sheet metal itself against evasion.
However, since the leaf springs can, as already mentioned, be relatively thin, there is only a minimal projection in the direction transverse to the press stroke.
In the subclaims, expedient and advantageous developments of the subject matter of the invention are defined, the resulting advantage being mentioned in the following explanation of exemplary embodiments. Reference is made to the accompanying drawings.

1 shows, in perspective, partially in section, a tool set consisting of male die and male die, which together with the press forms a device according to the invention,
2 shows a side view of each half of the symmetrically formed cutting parts for a die in embodiments a, b and c,
3 shows in vertical section half matrices in three embodiments a, b and c, respectively, modified from FIG. 1,
Fig. 4 shows special forms of matrices or patrices in versions a, b, c, d, e
5a shows, in perspective, partially in section, a further embodiment of the male and female mold,
5b shows a die similar to that of FIG. 5a,
6 serves to explain a preferred application of the device,
7 shows an overall device including a possible embodiment of the press,
8 shows a partial view of a device in which dies and dies are attached to rotating disks,
9a and 9b represent connections in longitudinal or cross-section of two sheets, in which an insert is provided in the manner of a rivet, and
10 shows in section, largely schematized, a device for establishing the connection according to FIGS. 9a, 9b.

1 shows the male part 10 with its stamp 12, which here has a rectangular cross section with a cutter 11 and can have a flat or somewhat spherical end face; its contour is preferably trapezoidal. - The die comprises the anvil 14 and two cutting parts 16, which are identical to one another. Anvil and cutting parts are captively connected, for example by a rivet 18. In In the area of this connection, the three components lie flat against one another, likewise in the end area facing the punch 12. In between, the anvil is so 'excluded on the sides facing the cutting parts that it has an approximately rhombic cross-section; the free spaces thus created allow chips that fall into it to be discharged to the outside without hindering the springing back of the cutting parts. In operation, the side of the cutting parts facing the anvil surfaces is supported in the foot region, where the rivet 18 is also seated, for example by means of a screw (not shown) which extends through the rivet and fastens the die to a holder which also holds it on the supports the side facing away from the stamp 12. The cutting parts can rebound in the area of their free end.
While the shape of the anvil and the stamp are shown in FIG. 1 roughly in accordance with reality, the shape of the cutting parts drawn there is not the cheapest. 2 and 3 show better shapes.
Experiments have shown that the stability of the device is essentially determined by the alternating stress on the cutting parts deflected in each work step. It is therefore preferred to design it in such a way that the deformation is distributed as evenly as possible over the free length - corresponding to the deflection of a beam clamped on one side under end loading - resulting approximately in the profile shown in Fig. 2a. In a simplified form according to FIG. 2b, the flanks of the cutting parts are semicircular, or one can - as shown in Fig. 2c - provide slot-like recesses 20 at the edge or slot-like openings 22 in the solid part of the cutting parts. Such different contours with the same cutting part thickness result in different spring characteristics, and this is necessary in order to adapt to different sheet qualities: With the same sheet thickness, the cutting parts for stainless steel should be much stiffer than for aluminum, for example.
It should be noted here that provision must also be made for different thicknesses of the sheets to be joined, in that the "depth" of the die, that is, the dimension between the counter cutting edges and the highest point of the anvil, is approximately the sum of the thicknesses of both sheets , reduced by an amount between 10% and 60%, preferably 30%. It can be seen that only the anvil parts have to be exchanged with the same cutting parts in order to obtain tool sets for other sheet thicknesses. The most favorable depth can be specified reproducibly either by limiting the press stroke or, and this is often the simpler solution, by limiting the force exerted by the presses.
Instead of the contour, you can also vary the shape of the spring longitudinal section. 3a, instead of a solid cutting part, leaf spring assemblies can be used, e.g. are interchangeable; as can be seen, only the innermost leaf springs 24 are riveted to the anvil and form the actual cutting part, while the rest are interchangeable and the whole package is inserted into a holding block 26.
As shown in FIG. 3b, it is also possible to form, in both cutting parts, together with a foot 28 as a one-piece component cut to length from a strand, in the U-shaped profile of which the anvil is inserted.
The cutting part cross-section was adapted to the cheapest deformation characteristic curve according to FIGS. 2a-2c by variable width of the cutting parts. However, the thickness of the cutting parts according to FIG. 3c can also be varied, with approximately the same characteristic being achieved as with the spring assemblies according to FIG. 3a.
The anvil part 30 according to FIG. 4a does not have the rhombus-shaped cross section as indicated in FIG. 1, but has a simple rectangular cross section in the central area. For this purpose, however, a roof-like slope 32 is provided on the foot side, along which the chips are conveyed to the outside.
As indicated in Fig. 4b, the two cutting parts need not be parallel; they can also lie over a corner and form the die with a "corner anvil" 36; the stamp cross-section 38 then has the shape of an equilateral, right-angled triangle.
Another variant, not shown, for the die has parallel cutting edges, but these are not located on the edge opposite the clamping or support point, but on a side edge running perpendicular to it. This means that the clamping point of the springs is not, as in all other embodiments, essentially under the patrix, but laterally therefrom, and accordingly the space under the patrix can be quite narrow. The fact that the conditions in the longitudinal direction of the cuts change because the die springs open to different degrees at both ends has not proven to be a problem.
According to FIG. 4c, two punches 12 'with a common die 40 can also work together in a press; two connection points are then obtained with each stroke, the connection being more secure than a single connection with a correspondingly enlarged cross-section.
It is even possible, as indicated in FIG. 4d, to cut both a male strip 42 and anvil and cutting partial strips 44 of any length from appropriately profiled primary material and then insert them into corresponding holding webs with which conventional presses - such as press brakes - can be fitted.
4e shows a perspective section of a complete tool, equipped with male parts P and female parts M. It can be seen that the upper tool 46 and lower tool 48 have both male parts and male parts; So that the metal sheets to be connected are not braced or even bent, the distance of the counter-cutting edges from the upper and lower tools is equal to the thickness of the two metal sheets to be connected when the tool is closed, ie in the deformation end position.
5a shows an embodiment in which the anvil 50 is designed as a circular cylinder, the height of which can be adjusted in the direction of the arrow relative to a base 52, for example by adjusting screws. The cutting parts 54 are in the form of hollow cylinder sectors or barrel staves which, apart from the separating slots between them, completely enclose the anvil. The separation slots can be designed in different numbers and different slot widths. On the base side, the cutting parts 54 are inserted or clamped in corresponding cutouts in the base 52. - The cutting parts can be made by slitting a sleeve or consist of individual segments.
There are two possibilities for the stamp 56 in the form of a simple circular cylinder. In the first case, the cross sections of anvil 50 and punch 56 are essentially congruent. In this case, as in the previously described embodiments, both sheets are cut through, and only in the area of the slits between the cutting parts do the pressed material slugs still hang on the surrounding sheet metal. The stamp can be in the area of the die slots Receive recesses so as not to constrict the remaining connecting webs.
In this respect, there is only a different outline shape of the connection compared to FIGS. 1 to 4a or 4b. However, if one chooses the stamp with cross-sectional dimensions 58, which are reduced by approximately twice the thickness of the sheet pressed through compared to the homologous dimensions of the anvil, the sheet is pressed through, but not cut, so that it is like a push button in the finished connection sits in the other sheet. Such a design enables the connection point to remain fluid-tight.
The circular cylindrical shape is of course in no way mandatory, and other polygonal outlines are also conceivable, for example square or hexagonal (cf. FIG. 5b for the matrix of a square connection point).
The production of complete tools according to FIG. 4e can be rationalized if one chooses a design according to FIG. 6.
In each case one die with ejectors 60 - for example in the form of spring-loaded pin - and one associated die with ejectors 60 are mounted on circular bases 62 of the same diameter. However, the ejectors can also be arranged in the area independently of the matrices or patrices. A male plate 64 and a female plate 66 are provided with column guides 68 and thus positioned in a reproducible manner relative to one another. Then both plates are drilled together at the corresponding points and inevitably drilled out Alignments bores 70 are then inserted into the base 62, which are rotated into a desired angular position and fixed in this. Damaged patrices or matrices can then be exchanged in a few simple steps.
Fig. 7 shows an example of a hand-held device equipped with a male 80 and a female 82. The male jaw 86 is articulated on the female jaw 84 by means of bearing bolts 88, and the cylinder body 90 of a high-pressure hydraulic cylinder is inserted into a recess of the female jaw Ram 92 actuates the male jaw in the sense of a press stroke. The provision is made by the tension spring 94.
Occasionally there will be a desire to close the depressions created by the joining process on the male side of the joined sheets. This can already take place in the course of the connection, and FIGS. 9a and 9b show a rivet-like insert N in two sections perpendicular to one another through such a connection. This insert to a certain extent represents the tip of the male part that remains in the connection.
Fig. 10 shows in section, largely schematic, a device with which such a connection can be made.
The die M is arranged in a conventional manner in a lower tool 100. A slot 102 is formed above it, into which the sheets 104, 106 to be connected fit with play. The lower tool has a guide channel 110 for the upper tool 108 above the die. A recess 112 extending transversely to it opens into this channel 110 and serves as a magazine for the rivets N. The means by which the stack of rivets is conveyed in the recess 112 are familiar to the person skilled in the art and are therefore not shown here.
Alternatively, a cut extruded profile can be inserted into the recess, from which the upper tool cuts off a rivet with each press stroke.
Such pliers-like design of the device have great advantages in that little space is required above and below the connection point and the connection can also be made in poorly accessible places. Surprisingly, the fact that the relative movement of the male and female dies no longer runs along a straight line, but along a circular arc, which may even have a relatively small radius, does not impair the usability of the device. Incidentally, the drive by a hydraulic cylinder is by no means mandatory; since straight guidance is not essential, a force-transmitting lever linkage can be provided, which even allows manually operated devices.
Fig. 8 shows an embodiment in which the male "P" and the female "M" are provided on the circumference of a disk 70 and 72, respectively, which are rotatable in the direction of the arrows. There is therefore no press in the usual sense of the word, but the two tool components are brought into operative connection with one another and with the plates 74, 76 by means of the rotary drive. In the left part of FIG. 8, the connection just established can be seen at 78.
The discs are located at the end of a floating shaft that is driven synchronously by a motor. The disks may be coated with a friction-enhancing material between the respective mating male-female combinations, e.g. have a soft rubber pad, or can also be corrugated.
It should be noted that the term "sheet metal" used above includes not only thin sheets (less than 2 mm thick) or middle sheets (less than 4 mm thick), but also heavy sheets, e.g. Aluminum 5 mm thick. It should also be noted that parts of extrusion or other profiles are to be understood as "sheet" in the sense of the invention. For example, a frame made of U-profiles can be connected to a sheet metal cladding with the aid of the subject matter of the invention. Finally, it should be noted that the two sheets to be joined (in the above sense) need not have the same thickness or may be made of different materials; so you can e.g. easily connect an aluminum sheet of 3 mm thickness with a stainless steel sheet of 1 mm thickness.

Claims

1) Device for rivet-like connection of sheets with a die and a patrix which can be moved by means of a press onto the die, between which the sheets to be joined lie flat one above the other, the patrix comprising a punch provided with cutting edges and the die counter-cutting edges and one behind the counter-cutting edges has set back anvil, on which the punch pressed through the material between the countercuts is extruded behind the incision edges, while the countercuts dodge laterally and are returned to their cutting position by spring preloading after the connection has been lifted out of the die, characterized in that the countercuts Leaf springs are clamped on one side by free end edges and extend parallel to the male movement.

2) Device according to claim 1, characterized in that the leaf springs have a rectangular cross section and are firmly connected to the anvil, which also has a rectangular cross section, in its clamping area.

3) Device according to claim 1, characterized in that the leaf springs have an annular sector cross-section and are firmly connected to the round cross-section having anvil in their clamping area.

4) Device according to claim 1, characterized in that the leaf springs have a cross-section tapering from their clamping area in the direction of the counter cutting edges.

5) Device according to claim 4, characterized in that the cross-sectional taper is set such that the bending stress is distributed at least approximately uniformly over the length of the leaf springs.

6) Device according to claim 4, characterized in that the leaf springs are formed by a layered package of individual lamellae.

7) Device according to claim 4, characterized in that the leaf springs have lateral recesses.

8) Device according to claim 4, characterized in that the leaf springs have openings.

9) Device according to claim 2, characterized in that a chip collection and discharge space is formed between the anvil and the leaf springs.

10) Device according to claim 9, characterized in that the chip collection and removal space is formed by undercuts of the anvil '.

11) Device according to claim 1, characterized in that the co-operating with the leaf spring counter-cutting on one between the incision edges remaining plug part are formed.

₁ 2) Device according to claim 11, characterized in that the stuffing part can be sheared off from a strand of material by means of an auxiliary cutting edge formed on the male part.

13) Device according to claim 1, characterized in that it has a plurality of male-female combinations in an upper or lower tool.

14) Device according to claim 13, characterized in that the upper and lower tools carry both male and female dies.

15) Device according to claim 14, characterized in that, in the position of maximum approximation of both tools, the counter cutting edges of the dies of both tools are at a distance from one another which is at least approximately equal to the thickness of the sheets to be connected.

16) Device according to claim 1, characterized in that it has elastic ejectors for releasing the sheets of male and female.

17) Device according to claim 16, characterized in that a die or a male with an ejector arranged together on a base forms an assembly assembly.

18) Device according to claim 13 and 17, characterized in that the bases are cylindrical and are inserted in bores of the upper or lower tool.

19) Apparatus according to claim 1, characterized in that the punch and die are each attached to the free end of a lever arm, which two lever arms are pivotable about a common pivot point in order to press the punch and die together.

20) Device according to claim 19, characterized in that a hydraulic working cylinder is provided for the pivot drive of the two lever arms relative to each other.