DE102008062989B4 - Method for joining two functional components and worm wheel - Google Patents

Abstract

Method for joining two functional components (1, 2), wherein one of the two functional components (1; 2) consists of a cast material, in particular a cast iron material, and the other functional component (2; 1) consists of a CuZn alloy,
wherein a material bridge (3) made of stainless steel between the first functional component (1) and the second functional component (2) is inserted and
wherein the first functional component (1) and the second functional component (2) are welded together via the material bridge (3).

Description

The invention relates to a method for joining two functional components of any shape. Preferably, a first functional component is a basic body which is of rotationally symmetrical design, while the second functional component is designed as a ring which is provided in the region of the peripheral edge surface of the basic body. The rotationally symmetrical basic body is, for example, a hub, a shaft or an axis. The wreath is then preferably designed as a worm wheel rim, as a gear wheel or generally as a component to be toothed. While one of the two functional components is preferably made of a cast material, in particular of a cast iron material such as gray cast iron or nodular cast iron, the other component preferably consists of a CuZn alloy, such as bronze or brass. Thus, for example, the main body can be made of a cast material, whereas the wreath is designed as a brass or bronze wreath. In particular, a worm wheel for a worm drive shows the last-mentioned construction.

It is common to pair steel screws with worm wheels made of a copper-tin alloy. Corresponding drives are manufactured and sold by the applicant. By the combination of bronze and steel, on the one hand, the service life of the transmission can be increased, on the other hand, the efficiency of the transmission is considerably improved. The disadvantage is, however, that bronze is relatively expensive. To minimize the material costs, usually only the outer functional component, so the wreath, made of bronze. The internal component is made of a less expensive material, such. As cast iron, made.

In order to permanently connect the two functional components, which consist of different, not or only partially weldable materials, it is known to fuse the external bronze component to the internal cast iron or gray cast iron component. Alternatively, the bronze material is spun onto the internal component. Both known manufacturing processes are time-consuming and associated with high costs.

From the JP 04 075 789 A For example, a welding method has been known in which a first base metal is welded to a second base metal by inserting a metal insert between the two base metals. Subsequently, the welding takes place by electron beam or laser welding. As a result, the susceptibility to cracking of the two base metals is reduced.

The invention has for its object to provide a cost-effective method, with the two functional components of non or only partially weldable materials are permanently connected to each other.

The object is achieved in that a material bridge made of stainless steel between the first functional component and the second functional component is inserted and that the first functional component and the second functional component are welded together via the material bridge. Here, the material bridge is shaped so that it is adapted to the corresponding shapes of the two functional components to be connected. By way of example, the material bridge is designed annularly if a rotationally symmetrical functional component is to be connected to a coronal functional component. The material bridge is made of a material that can be well welded to the materials of the two functional components. Preferably, the material bridge consists of stainless steel, for. From X5CrNi 18-10. Depending on the dimensions of the functional components to be joined, the material bridge usually has a thickness of 0.2 to 0.5 mm.

According to a development of the method according to the invention, the material bridge is applied to the circumferential outer surface of the base body. Based on the special case of the worm wheel described above, the annular material bridge is applied to the base body via a shrinking process. Alternatively, a rolled intermediate ring is placed on the circumferential outer surface. Subsequently, the ring is shrunk in the region of the peripheral outer surface of the annular material bridge on the base body with the annular material bridge.

An advantageous embodiment of the method according to the invention provides that the material bridge with the first functional component and the second functional component or with the base body and the rim over at least one welding process, which is preferably a laser welding process, is connected. Preferably, a solid-state laser is used. By means of a solid-state laser, a very good focusing of the laser beam can be achieved, which is essential for a sufficient welding depth and thus for a permanent assembly of the individual functional components. For processing, however, alternative laser sources known to the person skilled in the art can also be used. The welding depth is dependent on the dimensions of the components to be welded and is usually on the order of a few millimeters for worm gears for power transmissions.

Depending on the thickness of the material bridge and on the dimensions of the functional components, a one-sided welding process may already be sufficient to join the components together. If a single welding process is insufficient, the base body is welded successively in a first welding process with the material bridge and in a second welding process, the material bridge with the ring.

This welding process or the two welding processes are preferably carried out on one side. If it proves necessary, the welding takes place via a welding process or via two welding processes from both sides. This allows the stability of the welded joint to be optimized. The welding processes can be carried out both one after the other, ie first from one side and then from the opposite side, as well as from both sides at the same time.

In connection with the welding, it is considered to be very advantageous if an additional material is used for the purpose of regulating the quality of the molten bath. The additional material improves the connection of the base body and material bridge or of the material bridge and crown. The filler material is preferably formed wire-shaped and consists for example of CuSi3Mn. By choosing a suitable filler material, welding can be realized at the expense of process reliability even without a metal bridge.

It is considered to be particularly favorable if, during the welding process, the laser beam of the laser used for welding is displaced by the impact of the two functional components in the direction of the rim, or generally speaking, in the direction of the functional components made of the CuZn alloy. Preferably, the offset is on the order of 0.05 mm to 0.25 mm. This offset proves to be advantageous if no filler material is used in the weld. If a filler material is used, the offset is not required.

It is further provided that in a last method step, the outer edge of the ring is milled, or it is generated or refinished by alternative processes, the final contour of the ring.

As already mentioned, a worm wheel is preferably produced-but without any limitation-by the method described above. In this case, the main body is preferably made of cast iron or ductile iron. The material bridge is preferably a stainless steel insert, while the ring is made of a CuZn alloy, in particular of brass or bronze.

The invention will be explained in more detail with reference to the following figures. It shows:

1 : A plan view of an inventive worm wheel before the welding process and

2 : A plan view of an inventive worm wheel after the welding process.

1 shows a plan view of an inventive worm wheel before the welding process. The worm wheel 6 consists of a hub, which is the rotationally symmetric body 1 forms, a material bridge 3 and a wreath 2 , Around the base body consisting of cast iron material 1 with the wreath 2 To be able to weld from a CuZn alloy, is between the two functional components 1 . 2 according to the invention, the material bridge 3 inserted from a weldable material. For example, the material bridge exists 3 made of stainless steel.

According to a preferred embodiment of the method according to the invention, in a first method step, the annular material bridge 3 on the circumferential outer surface 4 of the basic body 1 applied. Either the material bridge becomes 3 if it is z. B. is a rolled stainless steel intermediate ring, simply hung up, or the material bridge 3 gets on the body 1 shrunk. For shrinking the aufzuschrumpfende component is heated to a temperature of about 80 ° C. In a second process step, the wreath 2 in the area of the peripheral outer surface 4 of the basic body 1 with applied or shrunk material bridge 3 on the main body 1 shrunk.

Subsequently, the material bridge 3 with the main body 1 and the wreath 2 permanently connected via at least one welding process. You can see it in 2 two welds 7 , The welding process is preferably a laser welding process which is carried out by means of a solid-state laser. By means of a solid-state laser, a very good focus of the laser beam can be achieved, what for a sufficient welding depth and thus for a permanent assembly of the individual functional components 1 . 2 . 3 is essential. The welding depth is on the order of a few millimeters and depends essentially on what loads the weld is subsequently exposed.

Depending on the thickness of the material bridge 3 and depending on the dimensioning of the functional components 1 . 2 Already a one-sided welding process can be sufficient for the functional components 1 . 2 to connect with each other. This embodiment is in 2 shown. If a single welding process is insufficient, then two welding processes can take place - one from each side. Should this be for a permanent connection of the functional components 1 . 2 . 3 not sufficient, it is intended to use two welding processes on both sides: In a first welding process, the main body 1 with the material bridge 3 and in a second welding process, the material bridge 3 with the wreath 2 welded.

It has proven to be advantageous if, before the welding process, first the joint between the body 1 and the material bridge 3 and the joint between the material bridge 3 and the wreath 2 be stapled. When stitching, the welding depth is much smaller than during the subsequent welding process. Without limitation, the following example is given: At a welding depth of 8 mm, the welding depth during stapling is preferably between 1-2 mm.

LIST OF REFERENCE NUMBERS

1

Main body, hub

2

wreath

3

material bridge

4

Outer edge of the main body

5

Outer edge of the wreath

6

worm

7

Weld

Claims (13)

Method for joining two functional components ( 1 . 2 ), one of the two functional components ( 1 ; 2 ) of a cast material, in particular a cast iron material, and the other functional component ( 2 ; 1 ) consists of a CuZn alloy, wherein a material bridge ( 3 ) made of stainless steel between the first functional component ( 1 ) and the second functional component ( 2 ) and wherein the first functional component ( 1 ) and the second functional component ( 2 ) over the material bridge ( 3 ) are welded together. Method according to claim 1, wherein the material bridge ( 3 ) on the circumferential outer surface ( 4 ) of the first functional component ( 1 ) is placed and / or stapled. Method according to claim 1 or 2, wherein the material bridge ( 3 ) with the first functional component ( 1 ) and the second functional component ( 2 ) is welded via at least one laser welding process. Method according to one of claims 1-3, wherein depending on the dimensions of the functional components ( 1 . 2 ) the material bridge ( 3 ) and the first functional component ( 1 ) or the material bridge ( 3 ) and the second functional component ( 2 ) are simultaneously connected together in a welding process, or wherein the first functional component ( 1 ) with the material bridge ( 3 ) in a first welding process and the material bridge ( 3 ) with the second functional component ( 2 ) are welded together in a second welding process. Method according to one of claims 1-4, wherein the welding is performed on one side or on both sides. Method according to one of claims 1-5, wherein for regulating the quality of the molten bath and for improving the connection of the first functional component ( 1 ) and the material bridge ( 3 ) or from the material bridge ( 3 ) and the second functional component ( 2 ) a filler material is used. Method according to one of claims 1-6, wherein the laser beam of the laser used for welding from the joint of the functional components ( 1 . 2 ) in the direction of the second functional component ( 2 ) is offset by an offset (V). The method of claim 7, wherein the offset (V) is on the order of 0.05 mm to 0.25 mm. A method according to claim 1 or any one of claims 3-8, wherein in the first functional component ( 1 ) around a rotationally symmetrical basic body and in the case of the second functional component ( 2 ) is a wreath and wherein an annular material bridge ( 3 ) on the circumferential outer surface ( 4 ) of the body is placed or shrunk. The method of claim 9, wherein the garland ( 2 ) in the area of the laid or shrunk material bridge ( 3 ) on the rotationally symmetrical basic body ( 1 ) is shrunk. Worm wheel for a drive, wherein the worm wheel ( 6 ) is manufactured by means of a method according to one of claims 9 or 10, wherein the base body ( 1 ) consists of cast iron, the material bridge ( 3 ) is a stainless steel insert, and where the wreath ( 2 ) is made of a CuZn alloy, in particular of brass or bronze. Worm wheel according to claim 11, wherein the material bridge ( 3 ) has a thickness of 0.2 to 0.5 mm. Worm wheel according to claim 10 or 11, wherein an outer edge ( 5 ) of the wreath ( 2 ) is milled.

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