DE3208304A1 - METHOD FOR CONNECTING SEVERAL ITEMS USING A RIVET - Google Patents

Description

■ G2Ü8-304

■ -.- '· 8.' March 1982

PATENT ADVOCATE \ .-. ' · DE

OR-RiCHARDKNEISSL '; '"'

V / icii .-. Mayerstr. 46

D-8000 MUNICH Tel. 089/295125

United Technologies Corp., Hartford, Ct./V.St.A.

Method for connecting several individual parts with the help of a rivet

description

The invention relates to a method for connecting several individual parts by riveting and in particular to a .s such a method in which a free play both in the longitudinal direction and in the transverse direction to the rivet shank to a large extent is prevented. '·

In the manufacture of precision devices such. B. Fuel regulators for gas turbines, riveted connections are required between moving parts. With fuel regulators For gas turbines, such items consist, for example, of levers, links and the like. Depending on the power requirement and perform a swivel movement from the operating status of the machine. The accuracy of the machine Fuel flow supplied by the regulator depends in large part Extents on the accuracy of the movement of such pivotable components. ■ ',

Typically, commercially available rivets made in such connections are used, a first head with a flat inner surface and a straight shaft, the perpendicularly protruding from the inner surface, wherein at the junction between the first head and the shaft a Rounding is present. The connection is established by that first the rivet shaft is inserted through holes aligned with one another in the individual parts and then the end of the shaft is molded into a second head is so that the items are held between the two rivet heads. The quality of the riveted joint (that The lack of free play) depends on the accuracy with which the holes in the individual parts are carried out by the Shank to be filled, and the accuracy with which the rivet heads on the surfaces of the outer individual parts

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issue. It turned out that there were deviations in the Shank diameters of commercially available rivets, in the shape of the head, in the geometry of the. Fillets at the transition from Head to shaft and in the eccentricity between head and ■ Shank in the known riveting techniques make the production more even Making swivel connections difficult if not impossible without undesirable free play. '·

Another problem associated with the rivet connections made by known techniques is that fatigue and permanent elongation of the rivets can occur when the connection is heated, for example to cure an adhesive used elsewhere in the device, or when the connection is used in a hot environment, which further contributes to the free play of the connection . . '■ .- ■ "-.-- ■" ^:

The invention was based on the object of a method for To create the joining of several individual parts by riveting, whereby the free play in the riveted connection is reduced and temperature changes being the 'free play in the connection do not enlarge. '■', ·

In the method according to the invention, the rivet head produced first formed so that the inner surface a Obtains concave shape and the cross-sectional area of the rounding is reduced to the seat between the head and an adjacent one Improve item. The rivet shaft is then inserted through aligned holes in the individual parts, and then the individual parts are pressed against the head, whereby 'the inner surface of the head by abutment is flattened to the adjacent item. While the individual parts are pressed against the first head, a second head at the free end of the shaft in a counterbore formed, which is formed in one of the bores so that

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Connection and the elastic elongation of the rivet is significantly reduced when the length of the rivet is shortened, which is made possible by the counter bore 65. The conical surface 70 improves the flow of the material of the shaft when its end part is formed into a second head.

In order to eliminate gaps between the individual parts and between the individual part 55 and the first head 15, the Items between the stamp. 47 and a hollow punch 75 pressed together. This is not just about the spaces in between but it also flattens the concave inner surface 20, thereby reducing the radially outer parts of the Rivet head are biased, .in such a way that when reshaping the shaft in a second head, the items between the Heads of the rivets are squeezed together.

While the individual parts by the 'hollow punch 75 firmly against'. The first head 15 is pressed, the end of the shaft 25 is reshaped into a second head 80 by the rivet along its longitudinal axis between the punch 47 and a full punch 85 is compressed, the riveted connection being finished is placed (Fig. · '4).

As already explained in more detail above, the manufacturing tolerances are of commercially available rivets in such a way that the diameter of the shaft and the geometry of the head and the fillet vary considerably, which also ■ for the eccentricity between Head and shaft applies. So that they can accommodate shafts of different diameters, the holes in the Individual parts 55 and 60 must be slightly larger than the maximum shaft diameter for commercially available rivets given specification is encountered. So it can be seen from Fig. 3 that the shaft and the shaft receiving Bores define an interspace which, if left in place, gives the finished connection considerable free play

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granted. If the item 60 had no counterbore, which, a reduction in the length of the shaft would then exist in the formation of the second head by known techniques, there is a risk of deformation of the shaft. Kink within the shaft-receiving bores. "If so the much shorter shaft .25 in production, of the head 80 is pressed together, then the above-described kinking which occurs during the production of a head according to FIG. known practice, avoided. Rather, the formation of the head 80 results in a upsetting or expansion of the Shaft, so that the shaft exactly fills the bores in the individual parts, which further reduces the free play in the connection. '

It is "thus evident that" by the "inventive method" drive the entire free play in a riveted connection .reduced will. The increase in diameter: the shank "provides a near-perfect fit between the shank and the holes in the individual parts The rivet head reduces the gaps caused by the well-known fillets and adapts the inner head surface firmly to the adjacent individual part. The maintenance a pressure of the individual parts on the first head during the formation of the second head reduces this Risk of a gap occurring between the individual parts itself or the individual parts and the first head. The formation of a counterbore reduces the length of the rivet shank and with it the thermal growth of the rivets and thus the free play of the connection. · '.

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Claims (5)

Claims [I.) Method for connecting several individual parts by means of a rivet, which has a first head with a flat inner surface and a shaft which extends perpendicularly away from the inner surface, with a fillet being present at the transition between head and shaft , in which method aligned.e bores are provided in the individual parts for receiving the rivet shank, the shank is inserted into the bores and the free end of the shank is formed into a second head, characterized in that before the formation of the second head a) the inner surface made into a concave shape is and at the same time, the cross-sectional area of the fillet is reduced by the head with its inner Surface is pressed against a die with a convex 'forming surface, and ·. . · b) the individual parts are pressed against the first head, to reduce gaps between the components and between the first head and the adjacent component. 2. The method according to claim 1, characterized in that that the pressing of the individual parts against the first head during the formation of the second head is maintained. 3. The method according to claim 1, characterized in that the first head during the deformation of the shaft in the recess of a stamp is located, whereby the pressing ' of the individual parts on the first head and during the training of the second head is maintained. 4. The method according to claim 3, characterized in that that the recess in the punch has a generally conical shape having. . 5. The method according to claim 1, characterized in that in the bore of the item which is to be trained second head is adjacent, a counterbore is provided. 6: The method according to claim 1, characterized in that in the bore of the individual part that is to be trained second head is adjacent, a counterbore is provided, wherein the second head is formed in the counterbore , whereby the required length of the rivet is reduced, resulting in a reduction in the plastic elongation of the Rivets due to thermal expansion as well as the elastic expansion of the rivet.