# Patent

## Title
Axle housing assembly and method

## Abstract

A method of forming a joint includes providing a first member made of cast iron having an exterior surface and a first end. A pocket is formed in the exterior surface of the first end. An insert made of steel is connected to the pocket. A second member made of cast iron is provided with an aperture. The method includes positioning the first end of the first member within the aperture and positioning a plug made of steel in the second member proximate the aperture. The plug is fixedly connected to the insert.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation of U.S. patent application Ser. No. 11/032,348 filed on Jan. 10, 2005. The disclosure of the above application is incorporated herein by reference.


FIELD OF THE INVENTION
The present disclosure relates to an axle housing assembly and more particularly relates to a device and a method for coupling a cast iron tube assembly to a cast iron carrier assembly.
BACKGROUND OF THE INVENTION
An axle housing assembly can include the carrier assembly and two tube assemblies that can be press-fit into the carrier assembly. The carrier assembly can hold a differential gear set and each of the tube assemblies can hold an axle shaft that can connect the differential gear set to each of a pair of wheels. Traditionally, the carrier assembly is made of cast iron and the tube assemblies are made of steel. Multiple components made from steel can be formed from or welded to each of the steel tube assemblies, for example steering knuckles, suspension brackets and/or hydraulic connectors.
In addition to coupling each of the tube assemblies to the carrier assembly with the press-fit, each of the tube assemblies can be slug-welded to the carrier assembly. Slug-welding, for example, can include forming a plurality of holes at two locations where each of the tube assemblies couples to the carrier assembly. Steel plugs can be inserted into the plurality of holes and contact each of the steel tube assemblies. The steel plugs can then be welded to each of the tube assemblies to further secure each of the tube assemblies to the cast iron carrier assembly.
In another example, each of the tube assemblies can be made from cast iron. Forming the tube assemblies from cast iron can reduce complexity and therefore save cost, but renders the connection of steel plugs to the tube assemblies somewhat more complex.
SUMMARY
The present disclosure relates to an axle housing assembly including a cast iron tube having a pocket. The pocket is formed proximate a first end of the cast iron tube. The pocket is also disposed generally transverse to a longitudinal axis of the cast iron tube. The axle housing assembly also includes an insert made of steel connected to the pocket.
A method of forming a joint includes providing a first member made of cast iron having an exterior surface and a first end. A pocket is formed in the exterior surface of the first end. An insert made of steel is connected to the pocket. A second member made of cast iron is provided with an aperture. The method includes positioning the first end of the first member within the aperture and positioning a plug made of steel in the second member proximate the aperture. The plug is fixedly connected to the insert.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It will be understood that the detailed description and specific examples, while indicating the various embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.



BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will become more fully understood from the detailed description, the appended claims and the accompanying drawings, wherein:
FIG. 1 is a top view of an exemplary vehicle showing an axle assembly housing constructed in accordance with the various embodiments of the present invention;
FIG. 2 is a perspective view of a carrier assembly and a tube assembly constructed in accordance with the various embodiments of the present invention;
FIG. 2A is a fragmentary perspective view showing another tube and insert configuration;
FIGS. 3A-3F are cross-sectional views showing various embodiments of a steel insert positioned in the tube assembly constructed in accordance with the various embodiments of the present invention;
FIG. 4 is a perspective view of the tube assembly showing an annular member made of steel disposed in an annular depression formed on the tube assembly constructed in accordance with the various embodiments of the present invention;
FIG. 5 is a cross-sectional view of FIG. 4 showing positions of the annular member with respect to a first end of the tube assembly; and
FIG. 6 is similar to FIG. 2 and shows the tube assembly coupled to the carrier assembly.



DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS
The following description of the various embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application or uses.
With reference to FIG. 1, an exemplary vehicle 10 is shown with an axle assembly 12 constructed in accordance with the teachings of the present invention. The exemplary vehicle 10 can include an engine 14, a frame 16, a transmission 18, a driveshaft 20, a pair of driven wheels 22 and a pair of optionally-driven wheels 24. The engine 14 produces an output having a torque component in a manner known in the art and transmits the output to the transmission 18. The transmission 18 can reduce the speed and increase the torque of the output produced by the engine 14 and transmit a torque to the axle assembly 12 through the driveshaft 20. The axle assembly 12 can transmit the torque to the pair of driven wheels 22 to propel the vehicle 10. It will be appreciated that the optionally-driven wheels 24 can connect to the transmission 18 in a manner known in the art (e.g., a four-wheel drive configuration).
With reference to FIGS. 2 and 6, the axle assembly 12 can include a carrier assembly 26 and two tube assemblies 28. The carrier assembly 26 can include a carrier housing 30 and a carrier housing cover 32 that is removably connected to the carrier housing 30 with a plurality of fasteners 34. The carrier housing 30 can define a carrier cavity 36 in which a differential gear set 38 can reside. The carrier housing 30 can be configured to include one or more suspension brackets 40, a pair of tube assembly apertures 42 and/or a pinion aperture 44. The suspension brackets 40 can connect to an exemplary suspension system in a manner that is well known in the art. The carrier housing 30 can be made of cast iron.
Each of the tube assemblies 28 can include a tube member 46 having a first end 48 that can be configured to connect with the carrier assembly 26 and a second end 50 that can connect with either one of the driven wheels 22 (FIG. 1). The tube assemblies 28 can include suspension brackets 52, steering knuckles 54, and/or a coil spring holder 56 if appropriate. An axle shaft 58 can be disposed in each tube member 46 and can be coupled for rotation with the differential gear set 38 and to one of the driven wheels 22 (FIG. 1) in a manner known in the art. Each of the axle shafts 58 can be journally supported for rotation by one or more axle shaft bearings (not shown) that can be housed in the tube member 46. The differential gear set 38 can be configured to transfer power received from the driveshaft 20 to the axle shafts 58.
Each of the tube assemblies 28 and the carrier housing 30 can be substantially made from cast iron and can be made from respective castings. It will be appreciated that the suspension brackets 40, 52, the coil spring holder 56, the pair of tube assembly apertures 42, the pinion aperture 44 and/or the steering knuckles 54 can be formed during the casting process. One exemplary type of casting process is commonly referred to as Lost Foam casting. The Lost Foam casting process and other exemplary suitable casting processes are disclosed in greater detail in commonly assigned U.S. Pat. No. 6,189,413 B1, entitled Captive Molding With Dissimilar Material Inserts, issued Feb. 20, 2001, which is hereby incorporated by reference as if fully set forth herein.
Each of the tube assembly apertures 42 on the carrier housing 30 can include a collar 60 that can be configured so that the tube assembly 28 can be press-fit therein. The collar 60 can include an outer annular surface 62 in which a plurality of holes 64 can be formed therethrough. The collar 60 can have a dimension that defines a thickness 66. A plurality of pins or plugs 68, which can be formed of steel, can be inserted into the respective holes 64 formed in the collar 60 and into contact with the tube assembly 28. It will be appreciated that the plurality of holes 64 can be formed in the collar 60 by various suitable forming processes, for example, machining the holes 64 into the collar 60 or forming the holes 64 in the collar 60 during an exemplary casting process. It will also be appreciated that the plugs 68 can be cast in place when the cast iron carrier housing 30 is formed in accordance with the methodology described in the above-referenced U.S. Pat. No. 6,189,413 B1.
With reference to FIGS. 2 and 3A-3F, the first end 48 of the tube assembly 28 can include one or more pockets 70. An insert 72 that can be made of steel can be disposed in the pocket 70. The pocket 70 can be formed in the first end 48 with various suitable methods, such as machining the pocket 70 in the first end 48. It will be appreciated that the pocket 70 can be formed during the casting process with the insert 72 disposed in and secured to the pocket 70. In the Lost Foam casting process, for example, the insert 72 can be placed in a foam mold (not shown) used in the Lost Foam process such that when molten iron is poured into the foam mold the finished casting will include the insert 72 fixedly attached to the pocket 70.
With reference to FIG. 3A, one embodiment of the present invention includes a bottom 74 of the pocket 70 that can have a curvature 76, which approximates a curvature of the tube assembly 28. A pair of walls 80 of the pocket 70 can be about parallel to each other. The pair of walls 80 of the pocket 70 can be formed such that the walls 80 would completely or partially converge, as indicated by reference number 82 and shown in FIG. 3E, or diverge as indicated by reference number 84 and shown in FIGS. 3C, 3D and 3F. It will be appreciated that a pair of sides 86 and a bottom 88 of the insert 72 can have a shape that is complimentary to the pocket 70. It will also be appreciated that the insert 72 and the pocket 70 need not be rectangular in shape but may be circular, oval or other suitable shapes. As such, a circular insert 72a received in a circular pocket 70a is shown in FIG. 2. Moreover, the various below described configurations of the pair of sides 86 of the insert 72 and the pair of walls 80 of the pocket 70 may be applicable to the circular insert 72a and the circular pocket 70a. 
With reference to FIG. 3B, one embodiment of the present invention can include the insert 72 that can have serrated or dovetail walls 89. The pocket 70 can have walls with a complementary shape, generally indicated by reference number 90, to further secure the insert 72 into the pocket 70. With reference to FIG. 3C, one embodiment of the present invention can include a mechanical fastener 92 that can be used to secure the insert 72 into the pocket 70. By way of example, the fastener 92 can be threaded through the insert 72 and the pocket 70 formed into the tube assembly 28. With reference to FIG. 3D, one embodiment of the present invention can include the insert 72 that can include a post 94 extending from the insert 72 into the pocket 70 formed in the tube assembly 28. The post 94 can extend in a direction toward a center 96 (FIG. 4) of the tube assembly 28. By way of example, an aperture 98 can be formed in the pocket 70 and be configured to accept the post 94, for example, with a taper-lock or an interference fit.
With reference to FIG. 3F, one embodiment of the present invention can include the insert 72 that can be placed in the pocket 70 and secured with a suitable adhesive 100. The adhesive 100 placed between the insert 72 and the pocket 70 can include various suitable acrylics or epoxies. Suitable adhesives for use in accordance with the present invention may include, for example, an acrylic adhesive comprising a urethane methacrylate. By way of example, one suitable acrylic adhesive is Loctite® 648, commercially available from Henkel Loctite Corp. of Auburn Hills, Mich.
With reference to FIGS. 4 and 5, one embodiment of the present invention can include an annular member 102 made of steel can be used in lieu of the above-mentioned inserts 72. By way of example, the annular member 102 can be placed in the foam mold (not shown) of the tube assembly 28 such that when the final casting is made, the annular member 102 can be positioned in an annular depression 104 adjacent to the first end 48. The annular member 102 in the annular depression 104 can be flush to an exterior surface 106 of the tube assembly 28. It will be appreciated that the annular member 102 can be located a predetermined distance from a terminus 108 of the first end 48 or flush with the terminus 108, as shown in FIG. 5. It will also be appreciated that the annular member 102 can be a complete ring or a partial ring and, to that end, the annular depression 104 can have a complementary shape (i.e., a partial or a full ring). It will further be appreciated that the distance at which the inserts 72, the pockets 70 and/or the annular member 102 is located from the terminus 108 of the first end 48 can be specific to each model of the axle assembly 12.
With reference to FIG. 6, the first end of the tube assembly 28 is inserted into the collar 60 on the carrier housing 30. The collar 60 can include a stop (not shown) to facilitate placement of the tube assembly 28 in the carrier housing 30 at a desired depth. The inserts 72 made of steel can be aligned to the plugs 68 and the plugs 68 can be welded to the inserts 72, for example, using a slug-welding process to thereby fixedly couple the tube assembly 28 to the carrier housing 30. The slug-welding process briefly includes, for example, heating the plugs 68 to a sufficient temperature whereby both the inserts 72 and the plugs 68 partially liquefy and then cool to form a single unit. By connecting the plugs 68, which are connected to the carrier housing 30, to the inserts 72, which are connected to the tube assembly 28, a steel-to-steel weld is formed. It will be appreciated that when the tube assembly 28 is slug-welded to the carrier assembly 26 both the slug-weld and the press-fit provide a robust connection to form the axle assembly 12.
Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, the specification and the following claims.

## Claims

1. A method of forming a joint, the method comprising:
providing a first member made of cast iron having an exterior surface and a first end;
forming a pocket in said exterior surface of said first end;
connecting an insert made of steel to said pocket;
providing a second member made of cast iron with an aperture;
positioning said first end of said first member within said aperture;
positioning a plug made of steel in said second member proximate said aperture; and
fixedly connecting said plug to said insert.

2. The method of claim 1 further including forming a through bore in said second member and aligning said insert with said through bore.

3. The method of claim 2 further including positioning said plug in said through bore.

4. The method of claim 1 further including aligning a top surface of said insert with said exterior surface.

5. The method of claim 1 wherein connecting said plug to said insert includes welding.

6. The method of claim 1 further including forming a serrated-structure on a pair of walls of said pockets, forming a complementary serrated-structure on said insert to said serrated-structure on said pair of walls, and connecting said serrated-structure on said pair of walls to said complementary serrated-structure on said insert.

7. The method of claim 1 wherein said pocket includes a pair of walls and a bottom portion having an angle between each of said pair of said walls and said bottom portion, and wherein said angle is one of an acute angle, an obtuse angle, and a right angle.

8. The method of claim 1 further including applying an adhesive between said pocket and said insert.

9. The method of claim 8 wherein said adhesive is an acrylic adhesive.

10. The method of claim 1 further including connecting said insert to said first member with a fastener.

11. The method of claim 1 wherein said insert is a ring and said pocket is an annular depression, said ring being connected to said annular depression.

12. A method of forming an axle assembly, the method comprising:
providing an axle tube made of cast iron having an exterior surface and a first end;
forming a pocket in said exterior surface of said first end;
positioning an insert made of steel within said pocket;
coupling said insert to said axle tube;
providing a carrier housing made of cast iron having an aperture;
positioning said first end of said axle tube within said aperture;
extending a plug made of steel through said carrier housing; and
fixedly connecting said plug to said insert.

13. The method of claim 12 wherein said pocket includes a recess extending inwardly from said exterior surface of said axle tube, said pocket extending a distance less than a thickness of said axle tube.

14. The method of claim 12 further including engaging a serrated wall of said pocket with a complementary serrated-structure of said insert.

15. The method of claim 12 further including positioning a top surface of said insert flush with said exterior surface of said axle tube.

16. The method of claim 12 further including welding said plug to said insert.

17. The method of claim 12 further including positioning a differential gear assembly within said carrier housing.

18. The method of claim 17 further including rotatably supporting an axle shaft driven by said differential assembly within said axle tube.

19. The method of claim 12 further including positioning another insert within another pocket formed in said axle tube, said inserts being circumferentially spaced apart from one another.

20. The method of claim 19 further including extending another steel plug through said carrier housing and fixing said another plug to said another insert.

21. A method of forming an axle housing assembly, the method comprising:
providing a cast iron tube with a first end;
forming a pocket proximate said first end of said cast iron tube;
coupling an insert made of steel to said cast iron tube, said insert being received in said pocket and a top surface of said insert being flush with an exterior surface of said tube;
providing a carrier housing at least partially made of cast iron, the carrier housing having a collar with an aperture; and
positioning said first end of said cast iron tube within said aperture.

22. The method of claim 21 further including fixedly connecting said plug to said insert.

23. The method of claim 22 wherein said plug is welded to said insert.

24. A method of forming an axle housing assembly, the method comprising:
forming a pocket in a cast iron tube, the pocket having a radially inner end wall that does not intersect an inside diametrical surface of the cast iron tube; and
coupling a steel insert to the cast iron tube, the steel insert being received in the pocket;
wherein a radially outer surface of the steel insert is flush with a radially outer surface of the cast iron tube.

25. The method of claim 24, wherein the pocket comprises a plurality of first side walls, wherein the steel insert comprises a plurality of second side walls and wherein at least a portion of one of the first side walls extends inwardly toward the steel insert to overlie at least a portion of one of the second side walls on a radially outer side of the at least the portion of the one of the second side walls to thereby resist removal of the steel insert from the pocket in a direction that is radially outwardly from the cast iron tube.

26. The method of claim 25, wherein a plurality of peaks and valleys are formed on the one of second side walls, the plurality of peaks and valleys being meshingly engaged to mating valleys and mating teeth, respectively, formed on the one of the first side walls.

27. The method of claim 25, wherein the at least the portion of the one of the first side walls extends over the at least the portion of the one of the second side walls in a circumferential direction along the cast iron tube.

28. The method of claim 24, wherein the steel insert at least partly forms the pocket as the cast iron tube is cast.

29. The method of claim 28, wherein the steel insert comprises a locking member into which molten cast iron material flows when the cast iron tube is cast, wherein solidification of the cast iron material received into the locking member inhibits withdrawal of the steel insert from the cast iron tube.

30. The method of claim 29, wherein the locking member comprises at least one inwardly extending surface on at least one side wall of the steel insert, the at least one inwardly extending surface extending in a circumferential direction along the cast iron tube, in an axial direction along the cast iron tube, or in both the circumferential direction and the axial direction.

31. The method of claim 24, wherein an aperture is formed in the pocket and wherein the steel insert comprises a post that is received in the aperture.

32. The method of claim 24, wherein the steel insert is bonded to the cast iron tube.

33. The method of claim 32, wherein an adhesive is employed to bond the steel insert to the cast iron tube.

34. The method of claim 24, wherein coupling the steel insert to the cast iron tube comprises securing a fastener to the cast iron tube.

35. The method of claim 34, wherein the fastener is thereadably engaged to the cast iron tube.