Providing interlocking recesses in the tubular shaft body of the axle

Abstract

A method for manufacturing a wheel axle for a utility vehicle such as a trailer, semitrailer, or truck, wherein the wheel axle comprises a hollow axle body having a steel tubular wall of thickness t and a clamping region adapted to be clamped between clamping components of a vehicle suspension by means of a tensioning device during use. An interlocking recess is formed in the clamping region. The interlocking recess is formed by a forming process in which a die member is pressed into the outer surface of the tubular wall to form a recess. The die dimensions and pressing force are such that the surface pressure on the stamping surface portion of the tubular wall locally exceeds the yield point to form the recess, and the pressing force causes the tubular wall portion adjacent to the interlocking recess to plastically recess inward by a distance that corresponds at most to the thickness t of the tubular wall. Preferably, the inward recess distance is in the range of 0 to 0.5 times the thickness t of the tubular wall. In an alternative method, the interlocking recess is formed by friction drilling a blind hole in the tubular wall of the axle body.

Description

Technical Field

[0001] The invention relates to a method for producing a wheel axle for a utility vehicle such as a trailer, semitrailer or truck, the wheel axle comprising an axle body comprising a steel tubular wall and having a clamping region adapted to be clamped between clamping parts of a vehicle suspension by means of a tensioning device, in use, wherein an interlocking recess is formed in the clamping region. Background Art

[0002] As a rough indication of the size of such a component only, it should be noted that in practice, a tubular axle body for a wheel axle of a utility vehicle may typically have an outer diameter of 146 mm and a wall thickness of approximately 8-15 mm. However, it should be noted that other dimensions are possible.

[0003] In the field of axle suspensions for utility vehicles, the axle body is typically a hollow, tubular body with a circular cross-section. The axle body is rigidly attached to the trailing arm via a clamping structure, which typically includes bolts or U-bolts that clamp the axle body to the trailing arm or to an intermediate component (such as an axle pad). Due to the axle body's circular shape, it is better able to withstand torsional loads than, for example, square axles. Torsional loads are primarily generated by the vehicle's rolling motion, which is transmitted to the axle body via the clamping device. However, the axle body's circular shape also has the disadvantage of making it more difficult to rotationally lock the axle body relative to other components (e.g., axles with a square cross-section). Over the years, many solutions for rotationally interlocking axles have been disclosed. One solution involves providing a recess in the axle body and a protrusion on one of the clamping components (e.g., the axle seat of the trailing arm or the axle seat of the axle pad). In particular, one solution provides the recess by deforming the axle body, thus eliminating the need for machining.

[0004] EP1334848 discloses an example in which a shaft is provided with interlocking recesses by pressing a spherical segment into the outer surface of a tubular shaft. A disadvantage of this known method of forming an interlocking recess is that it requires a counter-shape that is introduced into the tubular shaft and acts as a backing for the shaft wall in order to prevent deformation of the circular shape other than the desired recess.

[0005] Another example is known from EP2499009, in which an elongated notch with a circular cross-sectional shape is formed in the outer surface of a tubular shaft to provide an interlocking recess. In practice, this method is performed without a backing member for supporting the interior of the shaft during the formation of the notch. However, this requires heating the shaft.

[0006] Providing a backing member in the axle body or heating the axle body both results in the interlocking recesses having to be formed at an early stage in the axle manufacturing process, in particular before the axle stub is welded to the end of the axle body and / or the axle body is coated with a (corrosion protection) coating. In practice, this means that the axle manufacturer must provide the interlocking recesses, which may have different configurations for different customers, who are typically vehicle (e.g., (semi-)trailer) manufacturers or vehicle suspension manufacturers. It would be more advantageous to provide the interlocking recesses after the axle is manufactured and thus after the axle has been provided with the axle stub and coated. Summary of the Invention

[0007] The object of the present invention is to provide a method for manufacturing a wheel axle, wherein interlocking recesses can be formed in the axle body at the end of the axle manufacturing process.

[0008] This object is achieved by a method for manufacturing a wheel axle for a utility vehicle such as a trailer, semitrailer or truck, the wheel axle comprising a hollow axle body including a steel tubular wall of thickness t and having a clamping region adapted to be clamped between clamping members of a vehicle suspension by means of a tensioning device during use, wherein an interlocking recess is formed in the clamping region. The interlocking recess is formed by a forming process in which a die member is pressed into the outer surface of the tubular wall to form a recess, wherein the die is dimensioned and the pressing force is such that the surface pressure on the stamped surface portion of the tubular wall locally exceeds the yield point to form the recess, and the pressing force causes the tubular wall portion adjacent to the interlocking recess to plastically recess inwardly by a distance that corresponds at most to the thickness t of the tubular wall, preferably in the range of 0 to 0.5 times the thickness t of the tubular wall.

[0009] The present invention is based on the insight that if the outer surface area of the shaft body pressed inward by the die is small relative to the shaft body's diameter and wall thickness, the resistance of the shaft body material to the inward pressure is less than the bending resistance of the tubular wall. The total pressing force can be kept sufficiently low so that the shaft body does not deform as a whole, but rather the surface of the shaft body is locally subjected to sufficiently high pressure to induce plastic deformation. Thus, using the method of the present invention, very localized deformation is possible, and thus, very localized notches with well-defined edges are formed. Consequently, the inner side of the shaft body does not need to be supported by a backing member to maintain the shaft body's circular shape.

[0010] Furthermore, the method according to the invention can be performed using a cold forming process, which is advantageous because heating the shaft body is less detrimental to the material properties of the shaft body and the protective coating. Furthermore, the corrosion protection coating, which may be a cathodic dip lacquer (KTL) coating (which may be reheated for warm forming), can generate harmful fumes. The method according to the invention avoids this formation of fumes.

[0011] A further advantage of the method according to the invention is that it allows the suspension manufacturer to determine the distance between the axle clamping areas and thereby the width between the trailing arms that is deemed suitable for a particular suspension.

[0012] Preferably, the forming process is therefore a cold forming process. However, it is conceivable to preheat the surface of the shaft body very locally (for example by induction heating) before pressing the die onto the surface in order to locally lower the yield point.

[0013] As a result of the method of the present invention, the recess has relatively sharp edges and contours because the surrounding wall adjacent to the recess is not plastically deformed by the pressure, or at least is plastically deformed only to a small extent. At the same time, the shaft retains its strength in the recess. This is in contrast to manufacturing the recess by machining operations (e.g., milling), which results in a recess with sharp, well-defined edges but also leads to significant weakening of the shaft.

[0014] Preferably, the axle includes an axle end that is attached to each of the ends of the tubular axle body before the interlocking recesses are formed in the axle body. In this way, the axle manufacturer does not necessarily have to provide the interlocking recesses, but can be done by the suspension manufacturer or vehicle manufacturer as required.

[0015] Preferably, the axle body is provided with an outer surface coating before the interlocking recesses are formed in the axle body. This has the advantage, among other things, that the axle manufacturer can provide all necessary measures for the axle and the specific interlocking recess configuration can be manufactured on site at the suspension or vehicle manufacturer only according to its specifications.

[0016] Although the method according to the invention can be carried out on a tubular shaft body having any desired shape, it is in practice most useful when manufacturing shafts having a shaft body that is formed with a substantially circular cross section, at least in the clamping area, since such a circular cross section actually requires an interlocking device to prevent the shaft body from rotating in the clamping device.

[0017] In a possible embodiment of the method of the present invention, each time between two pressing movements, the die is shifted back and forth in the longitudinal direction so that a notch is formed during each pressing movement, wherein the notches abut each other and together form an interlocking recess. This particular method provides the possibility of manufacturing interlocking recesses that are larger than the notches that constitute them. Without wishing to be constrained by size, when the wall of the shaft body has a thickness of 8mm-15mm, the entire recess in a practical example can have a length of 30mm, a width of 10mm, and a depth of 6mm. In practice, the tubular shaft body typically has an outer diameter of 146mm, but other diameters are also used. In practice, at least two or three notches forming the recess are necessary to provide a sufficiently strong interlocking of the protrusion in the recess. However, it is also conceivable to provide a longer recess, for example having a length of 90mm, rather than three aligned recesses separated by a bridge.

[0018] Interlocking recesses are formed in the axle body to enable locking of the axle in the circumferential direction relative to other clamping components (such as the axle seat of the trailing arm, the axle pad or other clamping components). In particular, such clamping components will have associated protrusions, for example, elongated key-like protrusions integrally formed on the clamping component, or separate keys accommodated in the interlocking recesses in the axle body and in the interlocking recesses in the clamping component.

[0019] Preferably, the interlocking recess is formed to have an elongated shape having a longitudinal axis extending in the axial direction of the shaft body.

[0020] In one possible method according to the present invention, a plurality of interlocking recesses are formed in the clamping region of the shaft. These interlocking recesses can be formed in a staggered pattern. Alternatively, the recesses can be formed in a straight line. In a staggered or aligned pattern, the elongated recesses all extend parallel to the axial direction of the shaft.

[0021] Preferably, the recesses are formed with intermediate bridges between the longitudinal ends of consecutive recesses in the recess. The intermediate bridges provide rigidity to the tubular wall. However, there may be embodiments in which the bridges are omitted and the recesses are merged to form one large recess.

[0022] Preferably, the recess is formed with a tapered sidewall, wherein the depth of the tapered sidewall is less than the thickness of the tubular wall. By forming the recess in this manner, the force caused by the torsional load in the circumferential / tangential direction of the shaft body, applied by the interlocking protrusion received in the interlocking recess, is applied only to the wall of the tube, rather than radially inward from the wall of the tube. As a result, this force is optimally absorbed by the shaft body.

[0023] Furthermore, the tapered sidewalls of the recess allow the interlocking protrusions to be installed within greater dimensional tolerances. Furthermore, when the protrusions are slightly larger than the recesses, less shear load is applied to the tubular wall. Another advantage of the tapered sidewalls is that the die components are less susceptible to wear.

[0024] The objects of the present invention are also achieved according to a second aspect of the present invention. This aspect relates to a method for manufacturing a wheel axle for a utility vehicle such as a trailer, semitrailer or truck, the wheel axle comprising an axle body comprising a steel tubular wall and having a clamping region adapted to be clamped, in use, between clamping parts of a vehicle suspension by means of a tensioning device, wherein an interlocking recess is formed in the clamping region, wherein the interlocking recess is formed by friction drilling a blind hole in the tubular wall of the axle body.

[0025] During friction drilling, a hard metal, heat-resistant tool is rotated at high speed and pressed into the surface of the tubular wall of the shaft body. Due to the frictional heat, the tubular wall is locally heated and becomes flowable. In the method according to this aspect of the invention, the tool is not pushed completely through the tubular wall, so that a blind hole is formed in the shaft body. This blind hole can be used as an interlocking recess for an interlocking protrusion formed on a trailing arm, axle pad or other clamping member that engages the shaft body. The advantage of a blind hole is that it does not compromise the structural integrity of the shaft body and maintains the strength of the shaft tube as much as possible. Friction drilling can be done from the outside without the need for a backing member inside the tubular shaft body. In addition, the frictional heat is very localized, thereby eliminating possible damage to the surface coating of the shaft body only at the precise location of the recess.

[0026] The axle may already include an axle end that is attached to each of the ends of the tubular axle body before the interlocking recesses are formed in the axle body. In this way, the axle manufacturer does not necessarily have to provide the interlocking recesses, but rather can be done by the suspension manufacturer or vehicle manufacturer as needed.

[0027] Furthermore, the axle body can already be provided with an outer surface coating before the interlocking recesses are formed in the axle body. This has the advantage that the axle manufacturer can provide all necessary measures for the axle and the specific interlocking recess configuration can be manufactured on site at the suspension or vehicle manufacturer only according to their specifications.

[0028] Friction welding forms a collar on the outer surface of the tubular wall that surrounds the hole. The collar can be left there, but it can also be cut away.

[0029] As described above, a plurality of interlocking recesses may be formed in the clamping region of the shaft body by friction drilling. The interlocking recesses may be formed in a staggered pattern, but may alternatively be formed in a straight line.

[0030] In a possible embodiment of the method, a clamping member such as a trailing arm, axle washer, or other clamping component is placed against the clamping region of the axle body, and the interlocking recess is formed by means of friction drilling through the clamping member and into the axle body. Thus, according to this method, the blind hole is not formed directly in the axle body, but rather the hole is formed in the clamping member from the side facing away from the axle body.

[0031] In a particular embodiment, the clamping member has a through hole through which the friction drilling tool passes to drill into the tubular wall of the shaft body.

[0032] In a possible variant of the method, the friction drilling tool is held in a hole in the holding component and in a recess formed in the shaft body. The friction drilling tool is fixed when the holding component and the shaft body cool.

[0033] In a possible variant of the method, the drilling tool forms a recess in the holding part and a recess in the shaft body, wherein the material of the shaft body and the holding part melt / bonds together. Preferably, the drilling tool is held in both recesses.

[0034] The methods according to both aspects of the present invention, whether performed by cold forming or friction drilling, do not require supporting the tubular shaft wall from the inside during the production of the recesses. Instead, the shaft wall can be supported from the outside, preferably over as much of its circumference as possible. This helps prevent plastic deformation of the shaft body due to the formation of the interlocking recesses.

[0035] It should be noted that the interlocking recesses formed in the axle body offer the greatest advantages in the case of axle bodies having a circular shape (in particular a circular outer contour) which tend to loosen and rotate relative to the clamping device due to torsional loads. However, it is also conceivable to use the method according to the invention to provide interlocking recesses in axle bodies having other outer contours (for example a rectangular, in particular a square outer contour), which are also frequently used in air spring axle suspensions. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention is further explained in the following detailed description with reference to the accompanying drawings, in which:

[0037] Figure 1 schematically shows a side view of an embodiment of an air spring axle suspension comprising an axle body produced by the method according to the invention,

[0038] Figure 2 Show Figure 1 Longitudinal section of the axle clamping device of the wheel axle suspension,

[0039] Figure 3 Schematically shows a side view of another embodiment of an air spring wheel axle suspension comprising an axle body produced by the method according to the invention,

[0040] Figure 4 Show Figure 3 Longitudinal section of the axle clamping device of the wheel axle suspension,

[0041] Figure 5schematically shows a side view of a further embodiment of an air spring axle suspension comprising an axle body produced by the method according to the invention,

[0042] Figure 6 Show Figure 5 Longitudinal section of the axle clamping device of the wheel axle suspension,

[0043] Figure 7 and Figure 8 The method according to the first aspect of the invention is shown in perspective and in cross-section, respectively,

[0044] Figure 9 and Figure 10 Shown respectively by Figure 7 and Figure 8 The longitudinal section and the cross section of a portion of the shaft wall obtained by the method shown,

[0045] Figure 10A and Figure 10B A cross-sectional view of a portion of the shaft body showing interlocking recesses of different shapes,

[0046] Figure 11 and Figure 12 Shown respectively by Figure 7 and Figure 8 The longitudinal section and the cross section of a part of the shaft body wall and the shaft pad obtained by the method shown are as follows,

[0047] Figure 13 Show Figure 11 and Figure 12 An isometric view of a portion of the shaft pad is shown in

[0048] Figures 14A-14B showing cross sections of shaft bodies with varying amounts of plastic inward deformation on the side where the notch is formed,

[0049] Figure 15-18 shows isometric views of axle bodies made by the method according to the present invention, the axle bodies having interlocking recesses formed therein in different configurations,

[0050] Figure 19 Show Figure 17 A longitudinal cross section of a portion of the shaft wall of the shaft body combined with the shaft pad,

[0051] Figure 20-23 The method according to the second aspect of the present invention is shown in a front view, a perspective view and a cross-sectional view, respectively,

[0052] Figure 24-26 Shown respectively by Figure 20-23 The cross-sectional and longitudinal sections of a portion of the shaft wall and the shaft pad obtained by the method shown,

[0053] Figure 27 Show Figure 26 A portion of the shaft pad is shown in

[0054] Figure 28 shows isometric views of axle bodies made by the method according to the present invention, the axle bodies having interlocking recesses formed therein in different configurations,

[0055] Figure 29 An isometric view of an axle body produced by the method according to the invention is shown, the axle body having Figure 21 The same configuration with the ridge removed,

[0056] Figure 30 Show the use Figure 20-23 The cross section of a portion of the shaft body made by the method shown,

[0057] Figures 31A-31D Showing an alternative method according to the second aspect of the invention,

[0058] Figures 32A-32C Shows alternative approaches, and

[0059] Figures 33A-33C Another method according to the second aspect of the invention is shown. DETAILED DESCRIPTION

[0060] The present invention relates to a method for manufacturing a wheel axle for a utility vehicle such as a trailer, semitrailer or truck. Figure 1 A pneumatic spring wheel axle suspension 1 is shown, in which the axle body is produced by the method according to the invention.

[0061] The wheel axle comprises a tubular shaft body 2 extending in the transverse direction of the vehicle. The shaft body 2 is hollow and has a thickness t (see Figure 2 ) and has a steel tubular wall with a circular profile.

[0062] In practice, a typical tubular shaft body 2 has an outer diameter of 146 mm, but other sizes are possible. For example, shaft bodies with an outer diameter of 127 mm are also known. The thickness t may be somewhere in the range of 8 mm to 15 mm, for example 10 mm.

[0063] The suspension 1 further comprises a trailing arm 3 on either lateral side of the vehicle chassis, the trailing arm 3 being attached to the axle body 2 and extending in the longitudinal direction of the vehicle. The trailing arm 3 has an integrally formed eyelet 31 at its front end and an axle seat 32 at its rear end. In the particular embodiment shown, the trailing arm is made of spring steel and has a spring portion 33 between the eyelet 31 and the axle seat 32. The spring portion 33 is formed as a leaf spring and is designed to elastically deform during vehicle use so that the assembly of two parallel trailing arms and the axle body attached thereto can stabilize the vehicle by counteracting the vehicle's rolling motion. The eyelet 31 is adapted to pivotally couple the front end of the trailing arm 3 to a bearing bracket attached to the vehicle chassis by means of a pivot pin (e.g., a pivot bolt).

[0064] Associated with each of the trailing arms 3 is a corresponding rear arm 4. The rear arm 4 includes an axle seat portion 42 and a support arm 41 for the air spring 5. The support arm 41 extends from the axle seat portion 42 toward the rear. Figure 1 The air spring 5 is shown with its lower end mounted on a support arm 41. The upper end of the air spring 5 is attached to the vehicle chassis.

[0065] The axle body 2 is attached to the trailing arm 3 by a clamping device, Figure 2 The clamping device is further described.

[0066] The axle seat portion 32 of the trailing arm 3 and the axle seat portion 42 of the rear arm 4 each have a concavely formed axle engagement surface 35 and 45, respectively. The axle body 2 has a clamping area that is adapted to be clamped between the concavely formed axle engagement surfaces 35, 35 of the two axle seats 32, 42 during use. The axle seats 32 and 42 form a clamping member that is clamped around the clamping area of the axle body 2 by means of a tensioning device, in particular a tensioning bolt. Figure 1 and Figure 2 In the embodiment shown in FIG, the front end of the clamping device is tensioned by a U-bolt 7. This U-bolt 7 extends with its U-shaped bend over the nose 46 of the axle seat 42 of the trailing arm 4, and with its two legs extending through a counterplate 6 extending laterally on the top side of the trailing arm 3. Nuts 10 screwed onto the legs of the U-bolt 7 secure the front end of the clamping device. At the rear end of the clamping device, the axle seats are fastened toward each other by bolts 8 and nuts 9. Bolts 8 extend through holes in the respective rear ends of the axle seats 32 and 42. In alternative embodiments, the rear ends of the axle seats can also be clamped together by multiple bolts or U-bolts.

[0067] The interlocking recess 11 is formed in the clamping area of the shaft body 2. The interlocking recess 11 cooperates with the interlocking protrusion 47. Figure 1 and Figure 2In a particular embodiment of the invention, the interlocking protrusion 47 is integrally formed on the axle seat portion 42 of the rear arm 4 and, in particular, extends from the concave engagement surface 45 of the axle seat portion 42 of the rear arm 4. The axle seats 32 and 42 are rigidly clamped on the clamping area of the axle body 2. However, in practice, the clamping force alone is not sufficient to prevent relative movement between the circular axle body and the clamping parts 32, 42 in the rotational direction (tangential direction). Therefore, an interlock between the interlocking recess 11 and the interlocking protrusion 47 is provided. Therefore, torsional loads on the clamping device (in particular torsional loads caused by the rolling movement of the vehicle) will not lead to relative movement between the axle body 2 and the clamping parts 32, 42 and eventual possible loosening of the clamping device that could lead to failure of the suspension 1.

[0068] exist Figure 3 and Figure 4 , a wheel axle suspension is shown in FIG. , in which the trailing arm is a one-piece, integrally formed trailing arm 103. Trailing arm 103 is made of spring steel. Trailing arm 103 has an eyelet 131, an axle seat 132, and a spring portion 133 between the eyelet 131 and the axle seat 132. Trailing arm 103 has an integral support arm 141 for the air spring, integrally formed at the rear end of the axle seat. The axle body is clamped in axle seat 132 against a concavely formed axle engagement surface 135 by means of a U-bolt 107. The U-bolt 107 extends around the axle body with its curved portion 107A. One leg 107B extends upward from the front side of the axle body and along the lateral side of the trailing arm, while the other leg 107C extends upward from the rear side of the axle body and along the lateral side of the trailing arm 103. The strap 106 engages the upper side of the trailing arm 103 and contains holes through which the legs 107B and 107C of the U-bolt 107 pass. The U-bolt 107 is secured relative to the strap 106 by a nut 110.

[0069] The shaft body 2 includes an interlocking recess 11. The interlocking protrusion 147 is integrally formed on the shaft seat portion 132 of the trailing arm 103 and protrudes from the concave surface 135. Its function is the same as that of the above reference. Figure 1 and Figure 2 The functionality described is the same.

[0070] Figure 5 and Figure 6 A further embodiment of a wheel axle suspension is shown in . Unlike the embodiment of the previous figures, the axle body 2 in this embodiment does not rest directly against the trailing arm, but an intermediate component, a so-called axle washer, is arranged against the trailing arm, which axle washer forms the axle seat.

[0071] The trailing arm 203 is a one-piece, integrally formed trailing arm. It is made of spring steel. It has an eyelet 131 and a spring portion 133 extending from the eyelet toward the rear. The trailing arm 203 has an integral support arm 241 for the air spring, integrally formed on the rear portion. Between the spring arm and the support arm 241 lies an intermediate portion 232, where the axle body 2 is attached to the trailing arm 203. Axle washers 301 and 701 are located on the underside of the intermediate portion 232. Axle body 2 is clamped onto the concave axle engagement surface 335 of axle pad 301, 701 by means of a U-bolt 107. U-bolt 107 extends around axle body 2 with its curved portion 107A. One of its legs, 107B, extends upward from the front of axle body 2 and along the lateral side of trailing arm 203, while the other, 107C, extends upward from the rear of axle body 2 and along the lateral side of trailing arm 103. A strap 106 engages the upper side of trailing arm 103 and includes a hole through which legs 107B and 107C of U-bolt 107 pass. U-bolt 107 is secured relative to strap 106 by a nut 110. Thus, axle pad 301, 701 is clamped between axle body 2 and trailing arm 203.

[0072] The shaft body 2 includes an interlocking recess 11. The interlocking protrusions 347, 747 are integrally formed on the shaft seat portion of the shaft pad 301, 701 and protrude from the concave engagement surface 335. Their functions are the same as those described above with reference to Figure 1 and Figure 2 The functionality described is the same.

[0073] The above-described embodiments of the wheel axle suspension are to be regarded merely as non-limiting examples. However, many variations are conceivable.

[0074] According to the present invention, the interlocking recess 11 is formed in the shaft body 2 by a forming process that presses a die member into the outer surface of the tubular wall to form a recess. When forming the recess, the inside of the tubular wall does not have to be supported to prevent the shaft body from deforming too much around the recess.

[0075] exist Figure 7 and Figure 8, a shaft body 2 is shown in which three interlocking recesses 11 are aligned with each other in the longitudinal direction of the shaft body 2. A die member 501 is pressed into the outer surface 2A of the shaft body and forms a recess. The die member 501 has a tip 502 adapted to engage the surface in which the recess must be formed. The dimensions of the die 502, in particular the tip 502, are small enough so that the surface pressure on the stamped surface portion of the tubular wall locally exceeds the yield point to form the recess. The pressing force required to form the recess using the relatively small die 502 is very low so that the tubular wall portion adjacent to the interlocking recess 11 does not plastically deform in the radially inward direction, which deformation is sometimes referred to as "recessing", or at most recesses to a distance corresponding to the thickness t of the tubular wall. In practice, the recess is preferably maintained in the range of 0 to 0.5 times the thickness t of the tubular wall.

[0076] Figure 14A , the wall surrounding the recess 11 is shown without deformation, resulting in a sharp, well-defined edge for the recess 11. An advantage of having little or no inward deformation of the surrounding area 12 of the interlocking recess 11 is that the interlocking protrusions 47, 147, 347 are less likely to disengage or "roll out" of the interlocking recess 11. The less deformation in area 12, the more securely the protrusions can be held in the recess 11. Figure 14B , a situation is shown in which the surrounding area, in particular the area 12 along the longitudinal edge of the interlocking recess 11, is deformed inwards and thus deviates from the original circular shape. Figure 14B In the state shown in FIG, the adjacent wall portion at the edge of the recess 11 moves inwardly by a distance corresponding to the thickness t of the tubular wall of the shaft body. In practice, the thickness t may be about 10 mm, and the inward deformation will be in the range of 0 to 0.5 times the thickness t.

[0077] In a practical embodiment, Figure 7 and Figure 8 The recess 11 shown in FIG may have a longitudinal length of about 30 mm, a width of 10 mm, and a depth of 6 mm. The longitudinal length of the tip 502 of the die 501 may be quite small, for example, 10 mm to 15 mm, and the recess 11 may be made by pressing the recess, then retracting and translating the die several times and pressing overlapping recesses to form the entire recess 11. One or more recesses may be formed in the outer surface 2A of the shaft body 2 like this. For example, three recesses 11 may be in a straight line in the longitudinal direction of the shaft body 2, as shown in FIG. Figure 7-Figure 9 As shown. Figures 11 to 12 It can be seen that there are three protrusions 374 (see Figure 13 ) of the shaft pad 301 is received in the three recesses 11. In this way, the interlocking interface between the protrusion 374 and the recess 11 is provided with sufficient surface to prevent deformation due to torsional loads on the clamping device of the shaft body.

[0078] Using the method of the present invention, different recess patterns can be manufactured. Thus, the surface area of the interlocking interface between the recess and the protrusion can be varied, and the surface pressure can be varied and maintained between safe limits. Figures 15 to 18 Non-limiting examples of recessed patterns are shown in .

[0079] exist Figure 15 In the embodiment, the clamping area of the shaft body 2 may have two interlocking recesses 11 in a straight line with a considerable distance between the two interlocking recesses 11 .

[0080] exist Figure 16 , the clamping area of the shaft body 2 is shown to have an elongated recess 11A.

[0081] exist Figure 17 In FIG, the clamping area of the shaft body 2 is shown to have two parallel long recesses 11B. Figure 19 As shown in Figure 17 A cross section of the shaft body 2 is shown, wherein a shaft washer 301B having two parallel protrusions 374B is received in a parallel recess 11B formed in the shaft body 2 .

[0082] exist Figure 18 In FIG, the clamping region of the shaft body 2 is shown to have three recesses 11 , 11 ′, 11 ″, wherein the middle recess 11 ′ is offset from the other two aligned recesses 11 , 11 ″.

[0083] The cross section of the recess 11 can have different shapes. It can be a V-shaped groove, such as Figure 10A As shown, the side walls extend at an angle α (e.g. 45°) relative to the radius R at the center of the recess 11. It can also be a recess 11 with vertical side walls, such as Figure 10B As shown, the vertical sidewall is parallel to the radius R of the recess. Figure 10A The shape and Figure 10B There can be many cross-sectional concave shapes within the range between the shapes of Figure 10 In FIG, a practical embodiment is shown in which the side wall extends at an angle of approximately 10° relative to the radius R at the recess 11. This side wall bears against the side wall of the projection which is received in use in the recess.

[0084] In addition to the above-described method of forming one or more interlocking recesses in the shaft body by cold forming, there is another suitable method that does not require supporting the shaft body from the inside. This method includes forming one or more recesses in the shaft body by means of friction drilling.

[0085] exist Figure 20-23A specific method is shown in FIG, wherein a blind hole is formed in the shaft body 2. During friction drilling, a pointed hard metal heat-resistant tool 600 is rotated at high speed around its rotation axis and pressed into the outer surface 2A of the tubular wall of the shaft body 2. Due to the friction heat, the tubular wall is locally heated and becomes flowable. In the method according to this aspect of the invention, the pointed tool 600 is not pushed completely through the tubular wall, so that a blind hole 611 is formed in the shaft body 2. The blind hole can be used as an interlocking recess 11, which is used to form an interlocking protrusion on a trailing arm, axle pad or other clamping member that engages the shaft body 2, just like Figures 1 to 6 As shown. Friction drilling can be done from the outside without the need for a backing member inside the tubular shaft body 2. Furthermore, the friction heat is very localized, thereby eliminating any damage to the surface coating of the shaft body 2 only at the precise location of the recess 11.

[0086] When the blind hole 611 is formed, an annular ridge 612 is formed on the outer surface 2A of the shaft body 2. The annular ridge 612 surrounds the blind hole and protrudes from the outer surface 2A.

[0087] like Figure 21 As shown, a pattern of blind holes 611 can be formed in the shaft body 2, and in this particular example, three blind holes 611 are aligned in the longitudinal direction of the shaft body 2. Figure 27 , a portion of the shaft pad 701 is shown, which has three interlocking protrusions 774 that fit into the interlocking recesses 11 formed by the blind holes 611 in the shaft body 2. Figure 24 and Figure 26 , the interlocking projection 774 is shown in cross-section and longitudinal section, respectively, as being received in the interlocking recess 11 formed by the blind hole 611. As can be seen, there is an empty space between the bottom 611A of the hole 611 and the bottom surface 774A of the projection 774. Thus, the interface between the projection 774 and the hole 611 is formed by the circumferential surfaces of the projection 774 and the hole 611 engaging with each other. The projection 774 and the hole 611 preferably have conical circumferential surfaces so that the interface therebetween forms a support for the shaft body in the shaft pad.

[0088] exist Figure 25 In FIG. 5 , the force F at the interface is shown when the shaft pad and the shaft body are clamped together and the shaft clamping device is subjected to a torsional load. The bottom 611A of the blind hole 611 may be within the level of the undeformed tubular wall, as shown in FIG. Figure 24 As shown. Then, the force F caused by the torsional load will definitely be transmitted within the wall thickness t of the shaft body. Figure 25 In FIG, the depth H of the hole 611 is shown to be greater than the thickness t of the tubular wall. In this case, it is desirable that the protrusion 774 does not extend beyond the thickness t of the tubular wall so that the force F is absorbed directly in the wall thickness of the undeformed portion of the shaft body 2.

[0089] The shaft pad 701 has an annular groove 775 around the protrusion 774 (see Figure 27 ), the groove 775 is adapted to receive the annular ridge 612 surrounding the blind hole 611.

[0090] During friction drilling, the heated metal is partially pushed out of the recess formed. Tool 60 has Figure 20-23 The annular ridge 61 shown in FIG, below which an annular ridge 612 surrounding the blind hole 611 is formed by the heated metal being pushed upward. The tool annular ridge 61 is not suitable for removing material. However, the annular ridge 612 can be removed with the aid of the annular ridge 61 on the tool 60 that is suitable for removing material. Another option is to use a different tool to remove the annular ridge 612. The result is Figure 29 , in which the annular ridge 612 is removed from the outer surface of the shaft body 2 .

[0091] Figure 28 Different patterns of blind holes 611 and interlocking recesses 11 are shown.

[0092] exist Figure 30 In FIG. 1 , a practical embodiment of an axle body with a blind hole produced by friction drilling is shown, the axle body having a thickness t of, for example, 10 mm. The hole has an insertion depth H of 10 mm. i , that is, the depth of the receiving protrusion. The diameter D of the hole at the outer surface of the shaft body 2 h The outer diameter D of the shaft is 146 mm. The angle θ of the conical circumferential wall of the hole is about 20°.

[0093] exist Figures 31A-31C In FIG. 1 , a shaft seat portion 42 for connecting the shaft body 2 and the rear arm in this example is shown (see FIG. Figure 1 and Figure 2 ) between the interlocking engagement. In this method, the interlocking recess is formed in the shaft body through the shaft seat 42. In addition, the shaft seat 42 is provided with an initial blind recess 43 on the outside, such as Figure 31A As shown. The shaft seat portion 42 is positioned against the shaft body 2. Next, the friction drilling tool 62 is inserted into the initial blind recess 43 (see Figure 31B ) and operates to form a deeper recess by friction drilling. In this process, the material of the shaft body 2 is also deformed, thereby forming the interlocking recess 11 in the shaft body and the interlocking protrusion 47 in the shaft seat portion 42 in one step, as shown in FIG. Figure 31C As shown. Figure 31C Alternatively, the drilling tool or a portion thereof may fuse with the metal of the holding member 42 and remain in the hole, as in Figure 31D As shown, a stronger rotational interlocking connection is formed between the shaft body 2 and the shaft seat portion 42.

[0094] exist Figures 33A-33C, a variation of this method is shown in which the clamping member has an initial through-hole 44 into which a friction drilling tool 62 is inserted. The friction drilling tool 62 forms a blind hole or recess 11 in the shaft body 2 and fuses with the metal of the shaft body 2, which is locally flowable due to frictional heating. Thus, the tool 62 remains in the hole and forms an interlocking protrusion.

[0095] exist Figures 32A-32C In this method, the drilling tool 62 penetrates the shaft clamping member 42 and also penetrates the tubular wall of the shaft body 2, as shown in FIG. Figure 32C As shown. In this respect, this alternative method does not fall within the claimed invention. Due to frictional heat, the locally heated tubular wall becomes flowable, whereby the drilling tool 62 can fuse with the metal of the shaft body 2 and / or the metal of the clamping part 42 and remain in the hole.

[0096] like Figures 31A-31D 、 Figures 32A-32C and Figures 33A-33C The method shown allows for interlocking the axle body 2 with at least one axle clamping member 42 after the axle clamping members 32 and 42 are mounted to the axle body 2. Thus, the formation of the interlocking recesses and protrusions is a late step in the process of attaching the axle body to the trailing arm.

Claims

1. A method for manufacturing a wheel axle for a utility vehicle, the wheel axle comprising a hollow axle body comprising a steel tubular wall of thickness t and having a clamping area adapted to be clamped between clamping parts of a vehicle suspension by means of a tensioning device in use, wherein an interlocking recess is formed in the clamping area, wherein the wheel axle comprises an axle end which is attached to each of the ends of the tubular axle body before the interlocking recess is formed in the axle body, and wherein the interlocking recess is formed by a cold forming process in which a die member is pressed into the outer surface of the tubular wall to form a recess, wherein the size of the die and the pressing force are such that the surface pressure on the stamped surface portion of the tubular wall locally exceeds the yield point to form the recess, and the pressing force causes the tubular wall portion adjacent to the interlocking recess to plastically recess inwardly a distance corresponding at most to the thickness t of the tubular wall. 2 . The method according to claim 1 , wherein the pressing force causes the tubular wall portion adjacent to the interlocking recess to be plastically recessed inwardly by a distance in the range of 0 to 0.5 times the thickness t of the tubular wall. 3 . The method of claim 1 , wherein the shaft body is provided with an outer surface coating before the interlocking recesses are formed in the shaft body. 4 . The method according to claim 1 , wherein the shaft body is formed to have a circular cross section at least at the clamping region.

5. The method according to claim 1, wherein Each time between two pressing movements, the pressing die is displaced back and forth in the longitudinal direction, so that during each pressing movement recesses are formed, wherein the recesses abut one another and together form an interlocking recess. 6 . The method of claim 1 , wherein the interlocking recess is formed to have an elongated shape having a longitudinal axis extending in an axial direction of the shaft body.

7. The method of claim 1, wherein a plurality of interlocking recesses are formed in the clamping area of the shaft body. The method of claim 7 , wherein the interlocking recesses are formed in a staggered pattern.

9. The method of claim 7, wherein the interlocking recesses are formed in a straight line.

10. The method of claim 9, wherein the interlocking recesses are formed with intermediate bridges between longitudinal ends of consecutive interlocking recesses in the interlocking recesses.

11. The method of claim 1 , wherein the interlocking recess is formed with a tapered sidewall, wherein a depth of the tapered sidewall is less than a wall thickness of the tubular wall.

12. The method of claim 1, wherein the interlocking recess is formed with a tapered sidewall having an inclination relative to a radial line passing through a center of the interlocking recess, wherein the inclination angle of the tapered sidewall is in the range of 0°-45°.

13. The method of claim 1, wherein the utility vehicle is a trailer, a semi-trailer, or a truck. The method according to claim 12 , wherein the inclination angle of the tapered sidewall is in the range of 5°-20°.

15. A wheel axle for a utility vehicle, the wheel axle being manufactured by the method according to claim 1.

16. The axle according to claim 15, wherein the utility vehicle is a trailer, a semi-trailer or a truck.

17. An air spring vehicle suspension comprising the axle of claim 15 and further comprising a pair of trailing arms pivotally attached to a vehicle chassis and clamped against a clamping area of the axle body and an air spring operating between the axle and the vehicle chassis.

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