EP0155619A2 - Method for connecting metal sheets together - Google Patents

Abstract

Push-through method in which, thanks to the special design of the male and female molds, only one of the sheets is provided with incisions, resulting in a high-strength connection.

Description

The invention relates to a clinching method in which two sheets lying flat on top of one another are connected to one another by cutting, pressing through sheet metal material and extruding the pressed material behind the incisions. Regarding the term "enforcement", DIN 8593, Part 5, Section 4.5.2.11. to refer.

The invention further relates to a clinching device with which the method can be carried out.

A clinching device for joining sheet metal lying flat on top of one another, comprising a die with a central anvil part and with support parts projecting over an anvil work surface, resiliently arranged with respect to the anvil and provided with cutting edges at its free end, and a punch which passes through the die relative to the die Sheets can be moved towards the anvil work surface is disclosed in EP-B-00 77 932; with it, for example, the joint connection can be made in accordance with the aforementioned DIN sheet.

In the known device, the stamp or the stamps have a counter cutting edge for each die cutting edge, in the preferred case two parallel cutting edges and two counter cutting edges. The stamp cuts through both sheets along congruent lines, and the material pressed through on the die side is squeezed. - This known device has the advantage of very small dimensions relative to the thickness of the sheets to be connected, and both the punch and the die are very easy to manufacture.

Although, as practice has shown, the strength of the "joining point" created with the known device is by far sufficient in most cases, there was nevertheless a need to increase the skill of the connection and the object of the present invention is a clinching method and to provide a device suitable for its implementation, in which or in which the joining strength is increased compared to the values achievable with the known device.

To achieve this object, the method according to the invention is characterized in that only one of the sheets is provided with incisions and the pressed material is extruded on the side of the cut sheet facing away from the other sheet.

The device according to the invention is characterized in that the punch, at least in the area of its working surface facing the anvil, is narrower than the push-through area defined by the distance between the cutting edges.

In comparative measurements, it has been shown in a highly surprising manner that the strength of a joining point produced according to the invention exceeds that of joining points which were produced with the known device under otherwise identical conditions by at least 50% and up to 75%; the joint connection was subjected to shear loads parallel to the sheet surface and tensile loads perpendicular to it.

When using the invention, there is the further advantage that the non-cut sheet remains fluid-tight at the joint and that coatings such as galvanizing or plating are not cut through, so that generally a desired corrosion protection is retained.

Joining processes in which the joining point remains tight are known from DE-A-31 06 313. According to the teaching of this document, two sheets lying flat on top of one another are connected to one another in that a limited section of one sheet is pressed by means of a blunt stamp through the other sheet, which is also supported by a blunt die, after which both sheets pressed through are behind the first sheet facing away from the first Side of the second sheet are extruded laterally. For this purpose, two parts of the die can extend laterally. The pressed-through and extruded material portion of the sheet facing the die does not contribute to the joining strength; on the contrary, the material of this sheet hinders the extrusion of the material pushed through by the stamp-side sheet, so that poorer strength is to be expected. In addition, the jointed surfaces of the joint are all rounded, which should further deteriorate the strength under both shear and tensile loads. These considerations, based on the subject matter of the invention and the prior art, are of course based on the assumption of otherwise identical conditions (material quality and thickness, dimension of the joint, working pressure and working stroke).

In the device according to the invention, it has proven to be advantageous to form the edges delimiting the working surface of the stamp in a deliberately blunt manner by selecting an edge angle of more than 90 ° and / or rounding the edges. On the other hand, it must also be ensured that the sheet on the die side is really cut, and that the process of extrusion is also carried out in the desired manner. For the most important applications, it has turned out to be a useful compromise to design the stamp - starting from its working surface - in the shape of a truncated cone or pyramid (depending on the shape of the cutting edges) with a cone or pyramid tip angle of 30..50 ⁰ , whereby the determination is determined by the thickness and quality of the material of the sheets. An angle of 40 ° has proven itself for steel sheets of the same thickness.

The teaching of the invention is also applicable to devices in which a die has a stamp with several working surfaces, e.g. a double stamp is assigned. The invention can also be implemented with matrices in which the support parts can be exchanged to adapt to different material qualities and / or material thicknesses.

A particularly simple embodiment of the device is obtained if the die has only two support parts with cutting edges that are parallel to one another. In addition, this embodiment has the advantage that the alignment of the die and punch in the press used only has to be carried out with a high degree of accuracy in the direction perpendicular to the cutting edges, while the alignment across is less critical.

• Fig. 1 zeigt in Teilseitenansicht eine erste Ausführungsform, während die zu verbindenden Bleche im Schnitt gezeichnet sind,
• Fig. 2 stellt analog zu Fig. 1 die Teile nach Beendigung des Fügevorgangs dar,
• Fig. 3 zeigt perspektivisch im Teilschnitt eine mit der Vorrichtung nach Fig. 1 und 2 gefügte Verbindung, Fig. 4 ist eine Darstellung analog Fig. 3, jedoch in Richtung der Pfeile 4-4 in Fig. 3 gesehen,
• Fig. 5 ist eine Draufsicht auf die Fügestelle nach Fig. 3,4,
• Fig. 6, 7 und 8 zeigen Draufsichten auf die Matrizen weiterer Ausführungsformen von Vorrichtungen,
• Fig. 9 stellt in Seitenansicht einen Stempel einer weiteren Ausführungsform dar,
• Fig. 10 zeigt in zu Fig. 1 analoger Darstellung eine Matrize abweichender Konstruktion, und
• Fig. 11 ist eine Ansicht auf die Matrize nach Fig. 10 in Richtung des Pfeiles 11.

Embodiments of devices according to the invention are explained in detail below with reference to the accompanying drawings. The drawings are largely schematic and limited to the essentials; with regard to the structure in detail, reference is made to the EP-PS mentioned at the beginning.

• Fig. 1 shows a partial side view of a first embodiment, while the sheets to be connected are drawn in section,
• 2 shows, analogously to FIG. 1, the parts after the joining process has ended,
• 3 shows a perspective partial section of a connection made with the device according to FIGS. 1 and 2, FIG. 4 is an illustration analogous to FIG. 3, but seen in the direction of arrows 4-4 in FIG. 3,
• 5 is a top view of the joint of FIG. 3, 4,
• 6, 7 and 8 show top views of the matrices of further embodiments of devices,
• 9 shows a side view of a stamp of a further embodiment,
• FIG. 10 shows, in a representation analogous to FIG. 1, a die of a different construction, and
• 11 is a view of the die of FIG. 10 in the direction of arrow 11.

The press or press arrangement, in which the respectively associated and interacting parts - punch on the one hand, die on the other hand - are installed in alignment with one another, are not shown in the drawings. The direction of action of the press results from the summary of FIGS. 1 and 2, which show the two possible relative positions of the punch and die at the beginning and at the end of the press stroke.

First, reference is made to FIGS. 1 to 5.

The die comprises a stationary anvil 10 supported on its underside in the press with an essentially elongated, rectangular plan; Fig. 1 shows the side view on the narrow side. Support parts 12 extend along the broad sides of the anvil and can extend laterally (FIG. 2) and whose free edges facing the anvil are designed as cutting edges. The plane defined by the two cutting edges is one dimension higher than the somewhat convexly curved working surface 16 of the anvil, which is smaller than the sum of the thickness of both sheets 18, 20, but greater than the thickness of the sheet 18 facing it.

The punch 22 has a working surface 24 which - as can be clearly seen in FIG. 1 - is narrower than the distance between the two cutting edges: Jen corresponds to the die. Starting from this working surface, the cross section of the stamp increases, so that the area penetrating into the sheets has the shape of a truncated pyramid with a rectangular base, the angle of inclination of the pyramid sides relative to the stamp axis being approximately 20 ^c ; this corresponds to a tip angle of 40 °. The amount by which the work surface 24 is narrower than that The distance between the cutting edges depends on the thickness of the sheets, in particular on the thickness of the sheet 20 facing them, and is preferably dimensioned (for which a few attempts are sufficient) that this sheet 20 is no longer cut through when joining. The edge delimiting the working surface 24 is rounded, in the example with a radius of the order of 0.5 mm, and polished. The side faces of the truncated pyramid-shaped stamp section are designated by 26. The contour of the stamp on the sides extending perpendicular to the cutting edges is not shown in FIGS. 1 and 2, but can be seen in FIG. 9, which shows a stamp "that is different on the right than a doubling of the stamp from FIG. 1 une 2. It should be noted that here too the contour has approximately the same apex angle of the truncated pyramid as on the sides parallel to the cutting edge.

• Das Blech 18 ist längs der Schneiden 14, die sich ja senkrecht zur Zeichnungsebene erstrecken, durch das ZusammenwirKen derselben mit dem Stempel 22 eingeschnitten worden, und der zwischen den Einschnitten stehengebliebene Steg 30 ist bis zur Arbeitsfläche 16 des Amboß' durchgedrückt worden. Durch weiteren Druck (und damit Hub) des Stempels 22 ist der durchgedrückte Bereich 32 des Blechs 20, das nicht eingeschnitten worden ist, derart fließverpreßt, daß sein Material hinter die freigeschnittenen Kanten 34 unter fester Verankerung an diesen plastisch verformt ist. Der durchaedrückte Steg 30 bleibt mit seinen Enden 36 am Blech hänger, da cort Kein Einschnitt erfolgt ist. Die Fig. 3 bis 5 lassen die so erzeugte Fügung erkennen.

While Fig. 1 shows the state before joining, Fig. 2 shows the result that is present at the end of the press stroke (it should be noted that either the press pressure or the press stroke is specified):

• The sheet 18 has been cut along the cutting edges 14, which extend perpendicular to the plane of the drawing, by the interaction of the same with the stamp 22, and the web 30 which has remained between the cuts has been pushed through to the working surface 16 of the anvil. By further pressure (and thus stroke) of the punch 22, the pressed-through area 32 of the sheet 20, which has not been cut, is extruded so that its material is plastically deformed behind the cut edges 34 with firm anchoring to them. The pressed-through web 30 remains with its ends 36 on the sheet metal, because cort no incision has been made. 3 to 5 show the addition generated in this way.

In the first embodiment described so far, two parallel incisions were made in the sheet 18; the die and the stamp are very simple, inexpensive adjustable shape. If special requirements are placed on the appearance of the joining points, that is to say they are visible, for example, in everyday objects, an embodiment of the device as indicated in FIGS. 6 to 8 can be preferred. These embodiments are only shown as a top view of the die. The anvil 10 '(FIG. 6) or 10 "(FIG. 7) has the shape of a cylinder, and the support parts 12' or 12" have cutting edges which extend the sheet metal facing them along four (FIG. 6) or Cut three (Fig. 7) arcs with the same radius and common center. Between each of the incisions there remains a web which has the function of the webs 36 from FIG. 3. The working surface of the associated punches is indicated by 24 'or 24 "; the contour of these punches is then frustoconical with a tip angle of preferably 40, analogous to FIG. 1.

Finally, in the embodiment according to FIG. 8, four supporting parts 12 "'are arranged around an anvil 10"', which has a square outline; the webs then remain in the corner area. It should be noted that under certain circumstances it is also possible to dispense with standing webs. This would result in a closed circular incision shape in FIGS. 6 and 7, in FIG. 8 a closed square incision shape, with the result that a plate with a corresponding outline would be punched out of the sheet metal facing the die. The appearance of the joint would be very similar to a rivet head, but care would have to be taken to ensure that the die-cut plate is ejected from the die after each operation.

The stamp according to FIG. 9 is designed as a double stamp, in that two stamps according to FIG. 1 are arranged side by side and are made in one piece. One can see the two working surfaces 24a, 24b and the respectively assigned flanks 28, which extend perpendicular to the cutting edges and also define an apex angle of 40 °. The edges of the associated matrices are simply designed to be correspondingly longer, so that two adjacent joints are produced with one press stroke.

10 and 11 show a die in which the support parts are interchangeable.

The die includes a base 118 with a flat, one; Press table (not shown) parallel support surface 120 and a flat clamping surface 122 extending perpendicular thereto. A threaded bore 124 is machined into the base perpendicular to the clamping surface 122.

The support members 126, 128 and anvil 130 are separately manufactured components. The anvil 130 is an embossed steel part, and the support parts are stamped and erroneous, the area of their cutting edges 132 - both on their side facing the anvil and on its side facing the support parts are provided with a cutting edge - specially hardened or hard-coated and ground. The anvil and support parts have through holes which, when assembled, are in alignment with the threaded bore 124, the forces acting on the joining being transmitted to the base in that the support parts and anvil are supported on the support surface 120.

On the side facing away from the clamping surface 122 of the support part 126, a clamping plate 134 is provided, also provided with an aligned through hole. The entire assembly is held together by a clamping screw 136. In Fig. 10 the clamping screw is not yet tightened so that you can see that it is convexly curved outwards and thus acts as a spring washer. With its lower edge, it also lies on the support surface 120.

This embodiment has the advantage that the support parts can first be turned over when their cutting edges wear and, if the second pair of cutting edges is blunt, can be replaced. The anvil can also be replaced. Experience has shown that there is no wear on the anvil, but this enables the joining of sheets of different thickness, which in turn requires a change in the distance of the cutting edges 132 from the anvil working surface 138.

The upper edge 140 of the clamping washer is at the same height as the upper edge 142 of the clamping surface 122, so that the same clamping conditions are present for both support parts.

As can be seen from FIG. 11, the support parts have a contour with lateral cutouts, so that the bending stress during lateral rebound is distributed as uniformly as possible over the length of the support parts.

Claims (13)

1) clinching method, in which two sheets lying flat on top of each other by cutting, pushing through sheet material and extrusion of the pressed material behind the incisions are connected to each other, characterized in that only one of the sheets is provided with cuts and the pressed material on the other facing away from the other sheet Side of the cut sheet is extruded. 2) Method according to claim 1, characterized in that the one sheet is provided with two parallel incisions parallel to each other. 3) clinching device for joining sheet metal lying flat on top of one another, comprising a die with a central anvil part and with support parts projecting beyond an anvil working surface, which are resiliently arranged with respect to the anvil and provided with cutting edges at their free end, and a punch which is relative to the die can be moved through the sheets towards the anvil work surface, characterized in that the punch is narrower than the push-through region defined by the spacing of the cutting edges, at least in the region of its work surface facing the anvil. 4) clinching device according to claim 3, characterized in that the stamp has a truncated cone or truncated pyramid shape starting from its working surface. 5) clinching device according to claim 4, characterized in that the apex angle of the truncated cone or truncated pyramid is between ₃₀ ° and 50 °, preferably 40 °. 6) clinching device according to claim 4 or 5, characterized in that the edge delimiting the stamp work surface is rounded. 7) clinching device according to claim 6 for sheets up to a thickness of 2 mm, characterized in that the rounding radius is of the order of 0.5 mm. 8) clinching device according to one of claims 3 to 7, characterized by supporting parts each having a straight cutting edge, which two cutting edges are parallel to each other. 9) clinching device according to one of claims 3 to 7, characterized in that the cutting of all support parts lie on circular arcs with the same radius and a common center. 10) clinching device according to one of claims 3 to 7, characterized by supporting parts with two pairs of mutually perpendicular cutting edges. 11) clinching device according to claim 8, characterized in that a die is assigned a double punch with two adjacent work surfaces in the direction of the cutting edge extension. 12) Durchsetzfjgevorrichtung according to claim 8 or 11, characterized in that the support parts of the die are interchangeable. 13) Durchsetzfjugung two sheets lying flat on top of each other, in which only one of the sheets has incisions, between which material of the other sheet is pressed and is extruded behind the incision cans on the side of the sheet provided with incisions facing away from it.

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