Method of contact spot welding of rivet with plate of titanium alloys

FIELD: technological processes.

SUBSTANCE: opening with diameter of D0=(1.05-1.2)d is made in plate, where d- diameter of rivet rod. In top electrode insulating bushing is installed with external diameter of D1=(1.7-2.5)d, in which rivet rod is loosely fit. From the side of rivet head electrode is installed with flat working surface. Value of pulse current is set as equal to value of pulse at welding of packet from two sheets with the thickness of every one equal to the thickness of plate, with duration of pulse of 0.18-0.25 from duration of pulse during welding of package from sheets.

EFFECT: as a result, high quality joint is produced with high strength characteristics.

1 tbl, 7 dwg


The invention relates to the field of technology resistance spot welding and can be used in the manufacture of plate parts Osipovna.

There is a method of resistance spot welding rivets with plate (see Kochergin K.A. welding. - Leningrad: Mashinostroenie, Leningrad branch, 1987. - 240 S. Il. P.109, RIS). With this method of resistance welding in the upper electrode contact machines are doing the hole in which the rod set rivet. Regulate the height of the protrusion of the rivet head relative to the working surface of the upper electrode. Side plate place the electrode with a flat working surface. Then the electrodes are brought together to touch the rivet head surface plate, let the impulse of welding current and include upsetting effort.

Due to the current flow is heated parts in the contact zone of the rivet head with a plate formed of the liquid metal interlayer, crystallization of which is formed the connection.

The disadvantage of this method of welding rivet plate is the frequent formation of splash when forming compounds. This reduces the quality of the connection, which is unacceptable in the manufacture of critical parts, such as bushings mounting the radio waves of the cone of the aircraft from composite mother is La. In addition, the implementation of this method requires an additional device for the exact positioning of the rivet relative to each other (persistence step welding rivets).

The closest to the technical nature of the claimed method is a method of resistance welding rivets with countersunk head plate (Technology and equipment of welding. The tutorial. Edited by Orlov, D. - M.: Mashinostroenie, 1975. 536 S. Il. Page 172, RISS). With this method in the plate perform the hole, which creates a variant of the contact "sharp side". The high current density supported by the small area of contact between the sharp edges of the hole with an inclined surface of the rivet head.

The disadvantage of the prototype is the formation of compounds without the formation of liquid phase, which makes it not controlprogram. In addition, this variant form of connection is characterized by a great variation of strength (breaking stress).

The proposed method of contact welding rivets with plate ensures the formation of a liquid phase in the contact between the rivet and the plate and, as a consequence, stabilization of the strength properties of the obtained compounds.

The technical result, which directed this invention, is provided by performing in the plate hole the participation of diameter D o=(1,05-1,2)d, where d is the diameter of the shank of the rivet locations in the upper electrode insulating sleeve with an outer diameter of D1=(1,7-2,5)d, the position of the side plate electrode with a flat work surface, with the magnitude of the current pulse is set equal to the magnitude of the impulse welding package of two sheets, the total thickness is equal to the thickness of the plate, when the pulse width of 0.18 to 0.25 from pulse welding package of two sheets.

Read more the essence of the proposed method is illustrated by drawings:

1 shows a diagram of the Assembly of the rivet connection plate for welding in accordance with the inventive method;

figure 2 presents the microcracks on the surface of the rivet when forming connections with the diameter of the hole in the plate 1 less than 1,05d;

figure 3 presents the macrostructure of the connection diameter of the holes in the plate 1 over 1,2d;

figure 4 shows a diagram of the flow of welding current in the pulse period;

figure 5 presents the macrostructure connection with pulse duration less than 0.18 from pulse welding package of two sheets;

figure 6 presents the macrostructure connection with pulse duration from 0.25 pulse welding package of two sheets;

7 showing the macrostructure of the rivet connection with a plate of the Plava VTS, obtained in accordance with the inventive method to the optimal mode.

The proposed method of contact welding rivets with a plate of titanium alloys is carried out as follows. In plate 1 (figure 1) is a through hole with a diameter of Do=(1,05-1,2)d, where d is the diameter of the shank of the rivet 2. From the side of the rivet head 2 has the electrode 3 with a flat working surface. Rod side of the rivet 2 have upper electrode 4, which has an insulating sleeve 5. The inner diameter of the sleeve 5 is selected based on the installation software of the terminal rivet 2 in the sleeve on the free landing. The external diameter of the sleeve 5 is set by the ratio of D1=(1,7-2,5)d.

When the diameter of the hole in the plate is less than 1,05d is the contact edges of the hole with the rivet body 2 at the time of filing of the upsetting. In this part of the welding current passes from the electrode 4 through the plate 1 in the body of the rivet 2 and the electrode 3. As in this case, increasing the contact area between the plate 1 and the rivet 2, there is a decrease in current density and intensity of heating of the plate 1 in the connection zone. At upsetting the rivet 2 is pressed in enough of the heated metal plate, which causes the formation of micro-cracks on its surface (figure 2).

When the diameter of the hole in the plate more than 1,2d welding process has the t to a deep indentation of the rivet head 2 in the plate 1 with the formation of dents on the part of the rivet head and the bucket rod side of the rivet (3). Therefore, the optimum range of diameters of the holes in the plate 1 Do=(1,05-1,2)d, where d is the diameter of the shank of the rivet 2.

On the formation of connections in addition to the magnitude of the current pulse is greatly influenced by the external diameter of D1insulating sleeve 5 in the electrode 4. When the outer diameter D1less than 1,7d there is a small length of the zone of heating of the metal plate 1 near the hole. This causes great efforts during indentation of the rivet head in the plate 1. The molding compound becomes unstable and marked protrusion of the rivet head above the surface of the plate.

When the outer diameter D1more than 2,5d in the formation of seals observed deformation in the form of a trough in the welding zone plate 1 rivet 2 due to the low rigidity of the insulating sleeve 5 in the upper electrode 4.

Therefore, the optimal is the outer diameter of the insulating sleeve in the range of D1=(1,7-2,5)d, which provides the necessary heating of the plate 1 near holes and no residual deformation of the plate 1 in the connection zone after welding. The flow of current in this case is in the process of heating the compound shown by the arrows in figure 4.

The magnitude of the current pulse, which determines the temperature of the heating plate 1 and rivets 2 in the welding process, set equal to the current value when SV is the REC package of two sheets, the total thickness equal to the thickness of the plate. A more subtle regulation of the heat input into the connecting parts are produced by varying the pulse duration. The duration of the current pulse less, 0,18 from pulse welding package of two sheets, there is uneven heating of the plate 1 by the thickness and lack of education of the liquid core (figure 5). At pulse duration of more than 0.25 from the pulse current when welding package of two sheets with a total thickness equal to the thickness of the plate, there is excessive heating of the connected parts and the formation of a solid nucleus in the head of the rivet (6). This reduces the mechanical properties of the connection.

When the pulse width, 2.0-2.5 times greater than the duration of the current pulse welding package of two plates, there is the formation of a liquid ring core (7), providing the required strength of the connection.

Experiments were carried out by resistance welding plates of alloy VTS thickness of 2 mm rivet, alloy W 16 with a diameter of 2.5 mm Rivet had countersunk head. The length of the rivet head was 7 mm Before welding in a plate and carried out the hole diameter is varied in the range of 2.50-3,25 mm

For welding rivets with plate has been used machine for resistance spot welding brand MT-2023, virginialottery which was inserted sleeve from caprolactone. The external diameter of the sleeve was changed in the range of 4-6,5 mm. Internal diameter of the sleeve was 2.5+0.1 mm for the free occurrences of the stem of the rivet into the sleeve.

As welding mode mode has been selected for the formation of the welding spot diameter of 6.9-7.1 mm at the connection package of two sheets of alloy VTS thickness of 2+2 mm: the current pulse from 9.0 to 9.2 kA, pulse duration of 0.32, the compressing force of the electrodes 4,4-4,9 kN.

The results are shown in the table.

No. p.pThe diameter of the hole in the plate DoThe outer diameter of the insulating sleeve D1The current pulse, kAThe gain compression of the electrodes, HPulse width,Peculiarities of formation of connectionsDestructive force, kN
112,52,1the 5.259,13,20,07 The formation of cracks on the body of the rivet-
21,052,632,1the 5.25No cracks on the body of the rivet and forming connections flush with the plate surface-
31,12,752,1the 5.25
41,23,02,1the 5.25
51,33,252,1the 5.25The formation of dents in the plate by the rivet head-
61,12,751,64,09,13,20,07A small length of the zone of the heating plates and a large force compression of electrodes for forming connections-
71,12,751,74,25Does not require increasing the compression force of the electrodes when forming connections and no deformation of the plate in the connection zone-
81,12,752,1the 5.25
101,12,752,66,5The deflection of the plate due to the low stiffness of the upper electrode in the connection zone-
111,12,752,1the 5.250,05Molten core is missing or is present in some parts of the contact plate with rivet.5,5-6,4
121,12,752,1the 5.250,06Molten core is present throughout14,1 and 15.3
131,12,752,1the 5.259,13,20,77the surface of the rivet head on the perimeter of its contact with the plateof 15.5 and 16.2
141,12,752,1the 5.250,08The increase in the size of the cast core connection15,2-16,1
151,12,752,1the 5.250,10The formation of a solid nucleus in the head of the rivet and the reduction ol chestnykh characteristics of connections of 10.4 to 11.3

This shows that using the proposed method resistance spot welding rivets with a plate of titanium alloy provides a high quality connection with high strength properties. Application of the method is possible in the manufacture of needle bushing mounting radiotransparent cone made of composite material to the forward fuselage of the aircraft.

The method of resistance spot welding rivets with countersunk head with a plate of titanium alloys, in which the plate perform a through hole, into the hole installing rivet, the assembled connection feature between the electrodes contact the car, then through the electrodes pass a current pulse and implement draught, characterized in that the hole in the plate do with a diameter of Do=(1,05-1,2)d, where d is the diameter of the shank of the rivet, the upper electrode installing insulating sleeve with an outer diameter of D1=(1,7-2,5)d, which have a free landing rod rivet, side head rivet set the electrode with a flat working surface, and the magnitude of the current pulse is set equal to the magnitude of the impulse welding package of two sheets with the thickness of each equal to the thickness of the plate, and the pulse duration - (0,18-0,25) from long is eljnosti pulse welding package of sheets.


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