DE3613706C1 - Method of welding a stud to a metallic parent body, apparatus for carrying out the method, and stud for use during the method - Google Patents

Abstract

In a method of welding a stud (13) to a metallic parent body (8) by means of at least one arc (9; 10), at which a molten pool (S) is produced at the weld point and the stud is plunged into the molten pool, provision is made according to the invention first of all for the weld pool (S) to be produced in the region of the weld point (S) by means of at least one TIG torch (3, 4) or a torch derived therefrom with an arc (9;10) orientated in a fashion inclined to the surface of the parent body, and then for the stud (13) to be plunged through the arc, while being melted, into the weld pool at a predetermined speed down to a predetermined depth of immersion. <IMAGE>

Description

The invention first relates to a method for Welding a stud onto a metallic one Base body by means of at least one arc, in which a weld pool is created at the weld and the stud is immersed in the weld pool.

Such a method is known (cyc-arc method), by lifting off the stud at the welding point open circuit at the same time Arc is ignited. Thereby the Bolt at its tip becomes molten and forms the weld from the weld pool. After one the stud is set to the specified arc burning time immersed in the melt pool below and then the current switched off. The weld pool solidifies immediately afterwards. This welding process takes place in a split second and has due to the rapid solidification of the melt pool to have certain disadvantages, in particular can Pore inclusions and binding errors occur. Furthermore can in the known methods, the welding process only with great technical effort and only incomplete be reproduced. (see F. Eichhorn and A. R. Shaheeb: "Studies on arc stud welding from  high-alloy, scale-resistant steel pins; in Notices of VGB 50, number 6, pp. 504-516, in particular P. 507, No. 4.3.1.2.).

It is the object of the present invention Specify the method in which pore inclusions and Binding errors are largely avoided, and the Reproducibility of the welding process is improved.

This problem is solved by first in the area the welding point using at least one TIG torch or burner derived therefrom to the surface of the Base body inclined arc that Weld pool is generated and then the bolt underneath Melting through the arc with a predetermined Speed up to a specified immersion depth in the weld pool is immersed.

Regarding the details of tungsten inert gas welding (TIG welding, in the English-speaking world TIG welding) for example, the applicant refers to Ullmanns Encyclopedia of Industrial Chemistry (1981) Volume 20, pages 702, 701 and volume 21, pages 185-187. From this Literature also shows that one of the TIG welding derived welding process that Is plasma welding, and that both welding processes with or can be carried out without filler material.

When carrying out the method according to the invention, a homogeneous connection attaining one 100 percent seam connection achieved, and it was found that reproducible welding parameters can be met. It is believed that this is achieved in that first on the surface of the Basic body is a weld pool that is attached to the Cross-sectional geometry of the bolt is adjusted and then the bolt at such a speed and at one  such depth is introduced into the weld pool that on the one hand no pore inclusions and on the other hand none Binding errors can occur.

In the present application and in the claims under bolts not only round bolts but rod-shaped Components with any cross-sectional configuration Roger that. This can be particularly advantageous inventive method z. B. when welding on Head dowel bolts of larger diameter are used, the as fasteners of containers or the like. in Concrete or serve as holding elements for applied Insulation.

A particularly good adaptation of the weld pool to the Bolt cross section is achieved when multiple TIG torches in an even circumferential distribution on the welding point are aligned.

Furthermore, it is useful if the bolt when lowering into and through the area of the arc through and possibly also when immersing its axis is rotated.

For melting the bolt it is still from Advantage if a sharpened in a conventional manner Bolt is used.

Depending on the materials of bolts and / or Basic bodies and depending on the bolt cross section it may still be useful if the Stud welded connection by means of at least one Sweat filling is filled up. Such a filler weld also leads to heat treatment of the TIG welded connection, whereby this continues to be tempered becomes. The welding is preferably carried out in the Construction site technology.  

Finally, grinding the TIG welded connections or filler welding.

The invention is also directed to a device for Implementation of the method and goes a device with at least one burner and a bolt holder movable along its axis, which are held together in a device frame.

According to the invention, the torch is a TIG torch or a burner derived therefrom, which is vertical in the frame is arranged inclined to the axis of the bolt holder.

For the reasons of admission already mentioned, is preferably provided that at least in the frame two, preferably three TIG torches in uniform Distribution around the axis of the bolt holder are arranged.

It is also useful to the bolt holder in To mount the device frame rotatable about its axis.

In order to be able to set the thermal exposure to the welding point and to be able to use the method according to the invention in a wide variety of welding positions (Ü, S, W, Q) , it is advantageous if at least one torch is circumferential and / or with respect to the axis of the stud holder is adjustable radially to the axis of the bolt holder.

The device has for applying the filling layers preferably one around the axis of the stud holder orbital welding head.

The specified immersion depth can be maintained manually be, but it is more convenient if that Device rack a stop for limiting the Movement of the bolt holder toward the base body.  

The invention is also directed to a bolt which is in preferably when performing the method can be used. This bolt is in accordance with the invention characterized in that he is at his with the Base body to be welded at least one end conical tip and a subsequent im Reduced diameter compared to the bolt shank has cylindrical portion.

In a further preferred embodiment, the im Diameter reduced section a conical Transition section.

The invention will now be described with reference to the accompanying figures are explained in more detail. It shows

Fig. 1 is a schematic side view with two oppositely arranged TIG torches,

Fig. 2 shows a section through a finished weld joint,

Fig. 3 is a schematic representation of the welding device according to the invention in supervision with three TIG torches offset by 120 ° and

Fig. 4 is a partial side view of another embodiment of the bolt.

Referring to FIG. 1, the welding device (2) has two diametrically oppositely arranged TIG torch (3) and (4), each having a burner head (5) and a flexible connection (6). The electrodes ( 7 ) are aligned on a common center point (M) , which in the illustration according to FIG. 1 lies somewhat above the surface of the metallic base body ( 8 ) in order to make the illustration clearer.

However, it is also possible for the center point (M) to lie in the surface of the base body or by a predetermined amount in the base body ( 8 ) itself. The electrodes ( 7 ) are at a predetermined distance from the surface of the base body ( 8 ). The burners ( 3 ) and ( 4 ) are connected to one another and are simultaneously ignited by the operator by means of a one-button operation and are simultaneously switched off under the control of a timer.

When the arc is ignited, the arcs ( 9 ) and ( 10 ) of the burners ( 3 ) and ( 4 ) at a predetermined angle to the surface of the base body ( 8 ) cause a molten bath (S) on the component ( 8 ) .

The burners ( 3 ) and ( 4 ) are held in a device frame ( 11 ). In a preferred embodiment, they are arranged on a support ring ( 11 a) which is supported on the surface of the base body by means of support feet ( 11 b) . The conical inner surface of the support ring ( 11 a) determines the angle of inclination of the burner. The burner heads ( 5 ) are adjustable in a manner not shown by a slide guide in the radial direction and in the circumferential direction on the support ring ( 11 a) . The construction of such slide guides is in the area of expert skill and is therefore not described in detail. By suitable connecting elements (11 c) is connected to a guide and stop member (11 d) with the support ring (11 a). A bolt holder ( 12 ) is mounted axially in the direction of arrow (A) in the guide and stop component. The lowering of the bolt holder ( 12 ) and the rotation can be done manually. However, it is also possible to provide appropriate drives for this. The formation of such drives is also part of the professional ability.

A bolt ( 13 ) is held in the bolt holder ( 12 ), which consists of a conical tip ( 13 a) with a preferred cone angle of 150 °, a reduced diameter cylindrical section ( 13 b), a conical transition section ( 13 c) and the actual one Bolt section ( 13 d) . The cylindrical section ( 13 b) has a diameter of 10 mm, for example, while the section ( 13 d) has a diameter of 20 mm. The transition angle in the transition section ( 13 c) is designed so that the transition to the larger diameter of the bolt takes place at an angle of approximately 40 °.

After the build-up of the weld pool (S) on the component, the bolt ( 13 ) is slowly immersed into the weld pool from above while rotating, first preheating and melting the stud surface on the arcs ( 9 ) and ( 10 ) Flank angles of the machined conical bolt take place before the section ( 13 a) and part of the section ( 13 b ) dip into the weld pool (S) and form a homogeneous connection.

As can be seen from FIG. 2, a filling can be placed around the welded connection constructed according to the previous description of FIG. 1 by placing a number of fillings (FL) around the welded connection (V) . The stud weld connection can be filled mechanically with an orbital head or by hand with filler metal.

The build-up of the welded joint (V) can be carried out in less than ten seconds with an arc burning time without prior tacking to a diameter of e.g. B. 10 mm can be produced as a full seam connection. An intermediate test is not necessary. For larger diameters, however, it is advisable to apply fillings (FL) .

In the schematic representation according to FIG. 3, three TIG torches are arranged on the support ring ( 11 a) by means of slide guides ( 14 ), which need not be explained in detail, the needles of which are directed towards a center point. By means of the slide guides ( 14 ), the angular position and the radial position can be adjusted in order to adapt the welding process to different welding positions, e.g. B. to the S position, the effects of gravity on the weld pool can be compensated by the inert gas flows.

Fig. 4 shows an embodiment of a bolt that has no transition area ( 13 c) . In Figs. 1 and 3, the radial adjustability by the double arrows (R) and the adjustability in the circumferential direction by the double arrow (U) is indicated schematically

For holding the device frame (11) on the metallic base body (8), the feet may be formed (11 b) at their lower ends in a known manner as a magnetic feet or suction pads.

Claims (13)

1. A method for welding a stud onto a metallic base body by means of at least one arc, in which a weld pool is generated at the weld point and the stud is immersed in the weld pool, characterized in that first in the area of the weld site (S) by means of at least one TIG Torch ( 3, 4 ) or burner derived therefrom with arc ( 9; 10 ) inclined to the surface of the base body, the weld pool (S) is generated and then the bolt ( 13 ) is melted through the arc at a predetermined speed up to a predetermined rate Immersion depth is immersed in the weld pool. 2. The method according to claim 1, characterized in that several TIG torches ( 3, 4 ) are aligned in a uniform circumferential distribution on the welding point (S) . 3. The method according to claim 1 or 2, characterized in that the bolt ( 13 ) during lowering (A) into the area of the arc ( 9; 10 ) and through it and optionally also when immersed in the weld (S) is rotated about its axis (A) . 4. The method according to any one of claims 1 to 3, characterized in that a pointed bolt is used.   5. The method according to any one of claims 1 to 4, characterized in that the stud welding connection (V ) is filled up by means of at least one welding filler layer (FL) . 6. Device for carrying out the method according to one of claims 1 to 5 with at least one torch and a pin holder movable along its axis, which are held together in a device frame, characterized in that the torch is a TIG torch ( 3; 4 ) or is a burner derived therefrom, which is arranged in the frame ( 11 ) inclined perpendicular to the axis of the bolt holder ( 13 ). 7. The device according to claim 6, characterized in that in the frame ( 11 ) at least two, preferably three TIG torches are arranged in a uniform distribution around the axis of the bolt holder ( 12 ). 8. The device according to claim 6 or 7, characterized in that the bolt holder ( 12 ) in the device frame ( 11 ) is rotatably mounted about its axis (B) . 9. Device according to one of claims 6 to 8, characterized in that at least one burner is adjustable with respect to the axis of the bolt holder ( 12 ) in the circumferential direction (U) and / or radially (R) . 10. Device according to one of claims 6 to 9, characterized in that it has an orbital welding head rotating around the axis of the stud holder ( 12 ). 11. Device according to one of claims 6 to 10, characterized in that the device frame has a stop for limiting the movement of the bolt holder ( 12 ) to the base body ( 8 ). 12. Welding stud for use in carrying out the method according to one of claims 1 to 5, characterized in that it has at its end to be welded to the base body ( 8 ) at least one conical tip ( 13 a) and an adjoining one with respect to the diameter Bolt shaft ( 13 d) has a reduced cylindrical section ( 13 b) . 13. Welding stud according to claim 12, characterized in that on the reduced diameter section ( 13 b) is followed by a conical transition section ( 13 c) .