This Application is a 371, of PCT/FR00/00469, filed on Feb. 25, 2000; and French Application Serial Number 99/02476, filed on Feb. 26, 1999.
The present invention relates to a method of manufacturing a swaging ring which comprises a metal strip rolled into a hoop with its ends connected together by a connection element having at least one anchor edge.
Document EP-0 610 108 discloses a swaging ring made from a metal strip whose ends are of a thickness close to half the thickness of the strip and presenting, for example, fixing studs. To connect those ends together, a fixing plate, e.g. having holes, is put into place in such a manner that a stud is engaged in each hole. Thereafter, the free ends of the studs are riveted to the plate.
That method of manufacture and the ring it provides generally give satisfaction. Nevertheless, the method requires a first step which consists in reducing the thickness of the ends of the strip by half while simultaneously-forming fixing studs. The zones of reduced thickness and their studs then need to be dimensioned accurately so as to enable the fixing plate to be put and held in place, and the plate also needs to be made with great accuracy. Furthermore, a small amount of clearance is necessary between the plate and the strip and between the two ends of the strip in order to compensate for tolerances when positioning the studs in the holes of the plate. This clearance runs the risk of weakening the final connection.
In short, in that method, it is necessary to form the studs at the ends of the strip, to shape the plate, to put the plate into position while engaging the studs in the holes therein, to rivet the studs, and also to perform finishing operations (removing excess material, . . . ). That succession of operations turns out to be relatively lengthy and expensive.
The invention seeks to improve the above-mentioned method so as to overcome the drawbacks mentioned above.
This object is achieved by the fact that to connect said connection element to one end of the strip the connection element is placed against said end in such a manner that said anchor edge of the connection element is in register with said end, and pressure is exerted on the connection element in such a manner as to upset the material of said end of the strip lying beneath the connection element while providing a fixing member in said end suitable for co-operating with said anchor edge to hold the connection element and said end of the strip relative to each other in such a manner that the thickness of the ring in the region of the connection element is substantially equal to the thickness of strip.
As explained below, depending on which implementation is under consideration, the anchor edge(s) can be constituted by the edges of a hole formed in the connection element, or by an appropriate shape (indentations, angular cutouts, . . . ) in the outline or in one of the faces of the connection element.
The connection element is thus connected to the ends of the strip by a simple mechanical action of applying pressure which displaces the material situated beneath the connection element (cutting it or upsetting it). The connection element is integrated in the thickness of the strip, with the connection giving rise to no significant increase in thickness and the ring obtained in this way is cylindrical in shape, with inside and outside cylindrical surfaces that are smooth.
Once the connection element has been placed against the end of the strip, pressure is exerted on all or substantially all of the surface of the connection element which covers said end, thereby making it possible to integrate the connection element in the thickness of said end.
Once the connection element has been properly shaped with its anchor edge(s), it then suffices to perform a step of applying pressure so as to put said element into place and so as to provide connection by forming the fixing member(s) without there being any need to pre-form said fixing members. The connection element serves as a shaping tool and it remains in place in the ring to provide connection.
The connection element can be constituted by a connection piece that is separate from the strip, this piece having at least two anchor edges. Using such a piece, at least one fixing member is formed in each of the two ends of the strip, said fixing members being suitable for co-operating respectively with each of said anchor edges so as to unite the connection piece to both ends of the strip.
The overall shape of the connection piece can be that of a plate. It can also be of a different shape, possessing portions in relief, as explained below.
Thus, in the method of the invention, the connection piece is used directly as a tool for shaping the ends of the strip and is embedded in the two ends of the strip, and thus in the ring which it serves to connect together. Shaping is thus simplified and is obtained directly while the piece is being put into place. Furthermore, the connection between the piece and the ends of the strip is clearly achieved without clearance. As a result, any manufacturing tolerances concerning the piece or any inaccuracy in positioning it on the strip prior to applying pressure have no effect on the quality of the connection that is finally obtained.
In some cases, the connection element can also be made in a first end of the strip during a shaping step, and then in order to unite the two ends of the strip, the shaped first end is superposed on the second end of the strip and said pressure is exerted.
In this case, it is the first end of the strip which directly constitutes the connection element and which serves as the tool for shaping the second end of the strip in which it is embedded. The connection is finally obtained without any additional piece and without clearance.
In a first implementation, the connection element is used as a tool which serves both to flatten the end of the strip on which it is placed until the thickness of the ring in the region of the connection element is substantially equal to the thickness of the remainder of the strip, and to cause the material of said end to be upset, thereby leading to the formation of at least one fixing member against the anchor edge of the connection element. The connection element is embedded in the strip and remains embedded in the ring.
This upsetting of the material gives rise to total contact between the anchor edges of the connection element and the fixing members formed by the upsetting. For example, the connection element can have holes, in which case the fixing members are formed by studs or the like which are upset into the holes of the connection element.
As mentioned above, the connection element can be a piece that is separate from the strip. Under such circumstances, even if the end edges of the strip do not touch exactly when the piece is placed against the strip, e.g. because of cutting tolerances, the operation of applying pressure gives rise to strip material being upset, thereby serving not only to form fixing members, but also to fill any gap that may exist between said end edges.
In a second implementation, the connection element is used as a cutting tool. Under such circumstances, pressure is exerted on the connection element in such a manner that the material displaced by said connection element is cut away from the strip until the element occupies the volume previously occupied by the displaced and cut-away material, and the displaced and cut-away material is removed. In this case also, the connection element is embedded in the ends of the strip which it nevertheless cuts through over the entire thickness thereof.
Thus, even if manufacturing tolerances affect the dimensions of the connection element, clearance between the connection element and the strip is eliminated since cutting always matches the dimensions of the connection element.
Preferably, in this second implementation, a connection element is used which is constituted by a solid connection piece (generally having the shape of a plate) that is separate from the strip, and whose outline defines the anchor and cutting edges.
The invention also provides a swaging ring comprising a metal strip whose ends are connected together by a connection element having at least one anchor edge.
The invention seeks to improve the swaging ring known from document EP-0 610 108, as mentioned above.
This object is achieved by the facts that: the connection element is connected to one end of the strip by a fixing member formed against the anchor edge by said connection element being put into place; the connection between the strip and the connection element has no clearance; and the thickness of the ring in the region of the connection element is substantially equal to the thickness of the strip.
In the swaging ring of the invention, the fixing member(s) is/are formed directly by upsetting the material against the anchor edge(s) of the connection element or by a portion of the strip remaining against the anchor edge after the strip has been cut by the connection element, which element remains in place in the cutout. The quality of the connection between the connection element and the strip is reinforced by the absence of clearance, such that the ring is very strong and the connection between its ends is better at withstanding the swaging operation which occurs when the ring is put into place on the object to be swaged. The connection element is embedded in the strip.
In an advantageous embodiment, the connection element is constituted by a piece that is separate from the strip, in which case the anchor edge(s) can be formed by the edges of at least one hole in the piece or by some appropriate shape (indentation, angular cutout, . . . ) in the surface of said piece, i.e. in at least one of its faces and/or in its perimeter.
In another advantageous embodiment, the connection element is constituted by a first end of the strip having at least one anchor edge. Advantageously, the anchor edge is formed by a hole, and the first and second ends of the strip are flattened against each other, a stud belonging to the second end then being formed in said hole.
The invention also provides an installation for manufacturing a swaging ring comprising means for moving together the ends of a metal strip and for connecting the ends of said strip together by a connection element having at least one anchor edge.
The invention seeks to provide an installation that is simple, capable of production at high rates of throughput so as to enable swaging rings to be manufactured reliably and with practically no clearance in the region of the connections between their ends.
This object is achieved by the fact that the installation of the invention further comprises means for placing the connection element against one end of the strip so that at least one anchor edge of said connection element is in register with said end, and a press tool for exerting pressure on the connection element in such a manner as to upset the material of said end of the strip that lies beneath the connection element while providing in said end a fixing member suitable for co-operating with said anchor edge in order to hold together the connection element and said end of the strip in such a manner that the thickness of the ring in the vicinity of the connection element is substantially equal to the thickness of the strip.
By way of example, means for placing the end edges of the strip so that they face each other can be fitted to a rolling station in which the strip is progressively rolled up until its end edges come tip to tip or practically tip to tip. Under such circumstances, the connection element can be constituted by a connection piece fed from a magazine, which can be put into place against the strip by means for handling, setting, and positioning the piece. By way of example the press tool operates like a punch driven back and forth between a rest position in which it allows a strip and a connection piece to be put into position in register with said tool, and a working position in which it performs the operation of applying pressure on the connection piece. At the same time, the strip can be held in a setting counter-tool.
The connection element can be constituted directly by a first end of the strip, in which case the installation advantageously includes means for shaping said end into a connection element with at least one anchor edge (hole, . . . ), and the rolling-up station places one of the two ends of the strip against the other.