TECHNICAL FIELD

The present invention relates to a method of producing an arm of a suspension for a light commercial vehicle and the arm produced using said method.

BACKGROUND ART

Generally, arms of suspensions for commercial vehicles are made of steel via a forging process, or else via a process of casting of metallic material. Alternatively, the arms of the suspensions are produced by welding together sheared metal sheets .

The methods mentioned present the drawback of being very costly and requiring specific equipment. The arms obtained with the methods referred to above are at times unable to guarantee the requirements of sturdiness necessary for given applications. Furthermore, the arm obtained with the casting process is very heavy, and this causes an increase in the consumption of fuel and carbon-dioxide emissions.

DISCLOSURE OF INVENTION

The aim of the present invention is to provide a method of producing an arm of a suspension for a light commercial vehicle that will reduce at least one of the drawbacks of the known art .

According to the above aim, a method of producing an arm of a suspension for a light commercial vehicle is provided according to claims 1 to 10.

Another aim of the present invention is to produce an arm of a suspension for a light commercial vehicle that will reduce at least one of the drawbacks of the known art.

According to the above aim, an arm is provided according to claim 11.

Thanks to the present invention, an arm produced through an extrusion step is provided, which is inexpensive, light, and strong. The arm, given its lower weight, enables a reduction of pollutant emissions of the light commercial vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the present invention will emerge clearly from the ensuing description of a non-limiting example of embodiment thereof, with reference to the annexed drawings, wherein:

- Figure 1 is a top plan view of an arm for a suspension obtained according to a first embodiment of the present invention;

- Figure 2 is a side view of the arm of Figure 1 and of an extrusion die assembly of the arm of Figure 1 ;

- Figure 3 is a top plan view of an arm for a suspension obtained according to a second embodiment of the present invention;

- Figure 4 is a side view of the arm of Figure 3 and of die assemblies for extrusion of portions of the arm of Figure 3;

- Figure 5 is a top plan view of an arm for a suspension obtained according to a third embodiment of the present invention and of a die assembly for extrusion of a portion of the arm of Figure 5;

- Figure 6 is a side view of the arm of Figure 5 and of other die assemblies for extrusion of other portions of the arm of Figure 5;

- Figure 7 is a schematic view of the method of producing the arm of Figures 1 and 2. BEST MODE FOR CARRYING OUT THE INVENTION

With reference to Figures 1 and 2, designated by the number 1 is an arm of a suspension for a light commercial vehicle. The arm 1 extends substantially in a plane PI and, in use, is set between a hub assembly and a frame of a vehicle or a subframe of an axle assembly of a vehicle (not illustrated in the attached figures) . Preferably, the arm 1 is the upper arm of a suspension. In a preferred embodiment, the arm 1 extends in the plane PI .

In particular, the arm 1 comprises: a central body 2; a front branch 3; and a rear branch 4. The central body 2 comprises a vertex portion 20, which is constituted by a preferably cylindrical hollow element 10 and has a connection opening 9 that extends along an axis Al and is configured for housing a ball joint (not illustrated in the attached figures) designed to couple the arm 1 to the hub assembly (not illustrated in the attached figures) . In the case in point, the connection opening 9 is a hole of axis Al .

The front branch 3 comprises an end 5 facing the central body 2 and an end 6 facing, on the opposite side, the subframe (not illustrated in the attached figures) . The rear branch 4 comprises an end 7 facing the central body 2 and an end 8 facing the subframe (not illustrated in the attached figures) .

The branches 3 and 4 join up in the central body 2, in particular in a region corresponding to the hollow element 10. The branches 3 and 4 diverge at the ends 6 and 8. In particular, the branches 3 and 4 diverge on the side opposite to the central body 2. In particular, the branches 3 and 4 diverge on the side opposite to the connection opening 9.

The arm 1, then, is Y-shaped and has a free space 11 between the branches 3 and 4. Moreover, the central body 2 comprises a ribbing 12 that connects the branches 3 and 4. The arm 1 comprises a lightening opening 14 between the ribbing 12 and the hollow element 10. With reference to Figures 1 and 2, the arm 1 comprises a connection opening 15, which is made in the branch 3 and develops about an axis A2, and a connection opening 16 made in the branch 4 that develops about an axis A3. In greater detail, the connection opening 15 is provided at the end 6 of the branch 3, and the connection opening 16 is provided at the end 8 of the branch 4. In a preferred but non- limiting embodiment, the axis A2 and the axis A3 coincide.

The connection openings 15 and 16 are configured for connecting the arm 1 to the subframe (not illustrated in the attached figures) through sleeves (not illustrated in the attached figures) .

The axes A2 and A3 develop in a direction transverse to the direction of the axis Al . In particular, the axes A2 and A3 develop in a direction perpendicular to the direction of the axis Al . The axes A2 and A3 are parallel to the plane PI or lie in the plane PI.

In addition, the arm 1 extends in length in a direction oblique with respect to the axis Al and perpendicular to the axes A2 and A3.

With reference to Figures 2 and 7, the arm 1 or a plurality of arms 1 is obtained via a process that comprises: a step of extrusion along an axis AE1 to obtain an extruded profile 48; and a step of cutting the extruded profile 48 along cutting planes PT1 oblique with respect to the axis AE1 to obtain the arm 1 or plurality of arms 1. The axis AE1 is parallel to the axis Al . The axis AE1 is oblique with respect to the plane PI. The axis AE1 is perpendicular to the axes A2 and A3. In a preferred embodiment of the present invention, the arm 1 is made of an aluminium alloy, preferably series 6000 aluminium, in particular EN AW 6005A, or an alloy of the same family. The extrusion step is carried out with an extrusion die assembly 91. The die assembly 91 is a closed porthole die. The die assembly 91 comprises a mandrel and a die connected together (not illustrated in the attached figures) .

With reference to Figures 2 and 7, the die assembly 91 extends in a plane PP1 perpendicular to the axis Al . The plane PP1 is perpendicular to the extrusion axis AE1.

The die assembly 91 is a die that has a profile coinciding with the projection in the plane PP1 of the profile of the arm

I in the plane PI. The die assembly 91 has a profile coinciding with the projection in the plane PP1 of the profile of the connection opening 9 in the plane PI. The die assembly 91 has a profile coinciding with the projection in the plane PP1 of the profile of the lightening opening 14 in the plane PI. The die assembly 91 has a profile coinciding with the projection in the plane PP1 of the profile of the free space

II in the plane PI. The die assembly 91 has a profile coinciding with the projection in the plane PP1 of the profile of the central body 20 in the plane PI. The die assembly 91 has a profile coinciding with the projection in the plane PP1 of the profile of the branches 3 and 4 in the plane PI. Thanks to the die assembly 91 thus obtained, the production process is simplified as compared to the known art because, after the extrusion step and the step of cutting of the extruded profile 48, the shape of the arm 1 is complete, but for of the openings 15 and 16, obtained in subsequent perforating steps. The die assembly 91 is just one for the arm 1. Consequently, the production process enables production of a plurality of arms 1 in a given time interval.

In other embodiments of the present invention, the arm 1 is made of other metal alloys. In particular, with reference to Figure 7, the method envisages extrusion of a billet of metallic material 47 through the die assembly 91 along the axis AE1 to obtain the extruded profile 48, which is subsequently cut along cutting planes PTl oblique with respect to the axis AE1, to obtain a plurality of arms 1. Consequently, the planes PI are parallel to the cutting planes PTl. Furthermore, the cutting planes PTl are oblique with respect to the plane PP1. The extruded profile 48, prior to the cutting step, is heat treated by means of a solubilization step, a hardening step, and an artificial-ageing step. The solubilization step, which envisages bringing the metal to a temperature designed to trigger solubilization thereof, may be performed at the same time as the extrusion step or subsequently. In other words, if the temperature at which the extrusion step is carried out is suited to triggering the solubilization step, then the extruded profile 48 is hardened directly as it comes out of the extrusion mouth and subsequently undergoes a step of artificial ageing. If, instead, the extrusion step is carried out at temperatures lower than the solubilization temperatures, the extruded profile 48 is heated to trigger the solubilization step, is subsequently hardened, and finally undergoes artificial aging. The step of thermal treatment may not envisage the artificial-ageing step.

In other words, each arm 1 is obtained from a profile extruded along the axis AE1. The extruded profile is heat treated and subsequently cut along cutting planes PTl oblique with respect to the axis AE1 to obtain a plurality of arms 1. The connection opening 9 is obtained via the extrusion step. The lightening opening 14 is also obtained via the extrusion step.

The connection openings 15 and 16 of each arm 1 are obtained via a perforating step following upon the extrusion step. The extrusion step defines the shape of the branches 3 and 4 in the plane PI. In practice, the shape of the entire arm 1 is totally obtained via the extrusion step but for the connection openings 15 and 16. Thanks to the cuts along cutting planes PT1 oblique with respect to the axis AE1 arms 1 of length greater than the diameter of the mouth of the extruder are obtained. The arm 1 is a single body; in other words, the arm 1 is provided in a one-piece.

With reference to Figures 3 and 4, designated by the number

101 is an arm according to an alternative embodiment of the arm 1 illustrated in Figures 1 and 2. The arm 101 extends in a plane Pll and comprises a central body 102 and a front branch 103 and a rear branch 104, both removably connected to the central body 102 through fixing means 170, 171, 172, and 173. The central body 102 is substantially Y-shaped and has a vertex portion 120 and two lateral portions 121 and 122 that on one side are joined to the vertex portion 120 and on the other side diverge from one another. The vertex portion 120 comprises a preferably cylindrical hollow element 110 having a connection opening 109 that develops along an axis All and is configured for receiving a ball joint (not illustrated in the attached figures) . The vertex portion 120 further comprises lightening openings 114. Each lateral portion 121 and 122 comprises, respectively, an inner surface 130 and an inner surface 131 facing one another. In addition, the central body

102 comprises a stiffening ribbing 112 that connects the two lateral portions 121 and 122. Furthermore, the lateral portion 121 comprises an outer surface 132 opposite to the inner surface 130, and the lateral portion 122 comprises an outer surface 133 opposite to the inner surface 131. The outer surfaces 132 and 133 comprise an engagement portion 134 and an engagement portion 135, respectively.

The central body 102 has an opening 118 defined by the ribbing 112, the lateral portions 121 and 122, and the vertex portion 120. The branch 103 extends from an end 105 to an end 106. The branch 103 is connected to the central body 102, in particular to the lateral portion 121 at the end 105. The branch 103 comprises a connection surface 180 at the end 105. The connection surface 180 comprises an engagement portion 136 that is defined in a way complementary to the engagement portion 134 of the lateral portion 121. In use, the connection surface 180 faces and in part bears upon the outer surface

132.

The branch 104 extends from an end 107 to an end 108. The branch 104 is connected to the central body 102, in particular to the lateral portion 122, at the end 107. The branch 104 comprises a connection surface 181 at the end 107. The connection surface 181 comprises an engagement portion 137 that is defined in a way complementary to the engagement portion 135 of the lateral portion 122. In use, the connection surface 181 faces and in part bears upon the outer surface

133.

In particular, the engagement portions 134, 135, 136 and 137 are indented, or knurled, or grooved. In addition, the engagement portions 134 and 136 and the engagement portions 135 and 137 mate together so as to block the relative movement of the lateral portions 121 and 122 and of the branches 103 and 104 at least in one direction, preferably said direction being parallel to the plane Pll. In other words, the engagement portions 134, 135, 136, and 137 are indented, knurled, or grooved to enable a coupling without any relative sliding between the lateral portions 120 and 121 and the branches 103 and 104.

Each branch 103 and 104 comprises a respective connection opening 115 and 116 made along each end 106 and 108, respectively . The connection openings 115 and 116 develop along respective axes A12 and A13. In the non-limiting example represented in Figures 3 and 4 of the present invention, the axes A12 and A13 coincide. In particular, the axes A12 and A13 are parallel to or lie in the plane Pll. In particular, in the non-limiting example shown in Figures 3 and 4 of the present invention, the axes A12 and A13 lie in the plane Pll, which is in particular oblique with respect to the plane Pll.

In addition, the arm 101 develops in length transversely with respect to the axes A12 and A13, in particular perpendicular to the axes A12 and A13. Furthermore, the axis All develops in a direction transverse to the axes A12 and A13, in particular in a direction perpendicular to the direction of the axes A12 and A13. The axis All is transverse to the plane Pll.

The branch 103 comprises two connection holes 160 and 161 made in the end 105. The lateral portion 121 comprises two connection holes 162 and 163, which, in use, are aligned with the holes 160 and 161 for housing the respective fixing means 170 and 171 that connect together the branch 103 to the lateral portion 121. Furthermore, the holes 160 and 162 are made in regions corresponding to the engagement portions 134 and 136.

The branch 104 comprises two connection holes 164 and 165 made in the end 107. The lateral portion 122 comprises two connection holes 166 and 167, which, in use, are aligned with the connection holes 164 and 165 for housing the respective fixing means 172 and 173 that connect the branch 104 to the lateral portion 122. In addition, the holes 164 and 165 are made in regions corresponding to the engagement portions 135 and 137.

In particular, the fixing means 170, 171, 172, and 173 are screws, bolts, and bushings. The fixing means 170, 171, 172, and 173 have a structural function thanks to the presence of the bushings. In fact, the bushings are made of steel and constitute an internal reinforcement that withstands the loads .

With reference to Figure 4, the central body 102, the branches 103, and the branches 104 develop in the plane Pll.

The central portion 102 comprises connection holes 190. The holes 190 are obtained in the lateral portions 121 and 122 and in the vertex portion 120. The arm 101 comprises a plate 150, which is connected to the central portion 102 via the connection holes 190 and comprises a flange 151 for connecting one end of a shock absorber. The flange 151 has openings 152 made along the axis A16 parallel to the axes A12 and A13. In particular, the plate 150 has a rectangular shape and bears upon the ribbing 112 and upon the vertex portion 120 on two opposite sides and is in contact with the lateral portions 106 and 107 on the other two opposite sides. The plate 150 is configured to bestow greater stiffness upon the central portion 102.

The arm 101 is obtained via a process that comprises steps of extrusion along an axis AE11 of a billet of metallic material to obtain an extruded profile, and steps of cutting the extruded profile along cutting planes that are oblique with respect to the axis AE11. The axis AE11 is parallel to the axis All. The axis AE11 is oblique with respect to the plane Pll. In a preferred embodiment of the present invention, the arm 101 is made of aluminium alloy, preferably series 6000 aluminium, in particular EN AW 6005A, or an alloy of the same family. The arm 101 is obtained via three extrusion steps with respective three extrusion porthole-die assemblies 191, 192, and 193 for the central body 102, for the branch 103, and for the branch 104, respectively. The three porthole-die assemblies 191, 192 and 193 are represented in Figure 4 as being set on top of one another. In addition, the three porthole-die assemblies 191, 192, and 193 may comprise a mandrel and a die (not illustrated) like the die assembly 91.

The die assembly 191 is used to obtain an extruded profile, from which a plurality of central bodies 102 are obtained. The die assembly 191 extends in a plane PP11 that is perpendicular to the axis All and to the axis AE11.

The die assembly 191 is a die that has a profile coinciding with the projection in the plane PP11 of the profile of the central body 102 in the plane Pll. The die assembly 191 has a profile coinciding with the projection in the plane PP11 of the profile of the opening 109 in the plane Pll. The die assembly 191 has a profile coinciding with the projection in the plane PP11 of the profile of the lightening opening 114 in the plane Pll. The die assembly 191 has a profile coinciding with the projection in the plane PP11 of the profile of the lateral portions 121 and 122 in the plane Pll. The die assembly 191 has a profile coinciding with the projection in the plane PP11 of the profile of the ribbing 112 in the plane Pll. The die assembly 191 has a profile coinciding with the projection in the plane PP11 of the profile of the engagement portions 134 and 135 in the plane Pll. The die assembly 191 has a profile coinciding with the projection in the plane PP11 of the profile of the opening 118 in the plane Pll.

The die assembly 191 has a profile coinciding with the projection in the plane PP11 of the profile of the outer surfaces 132 and 133 and of the inner surfaces 130 and 131 in the plane Pll.

The die assembly 192 is used to obtain an extruded profile, from which a plurality of branches 103 are obtained.

The die assembly 192 has a profile coinciding with the projection in the plane PP11 of the profile of the branch 103 in the plane Pll.

The die assembly 192 has a profile coinciding with the projection in the plane PP11 of the profile of the contact surface 180 in the plane Pll. The die assembly 192 has a profile coinciding with the projection in the plane PP11 of the profile of the engagement portion 136 in the plane Pll. The die assembly 192 has a profile coinciding with the projection in the plane PP11 of the profile of the ends 105 and 106 in the plane Pll.

The die assembly 193 is used to obtain an extruded profile, from which a plurality of branches 104 are obtained.

The die assembly 193 has a profile coinciding with the projection in the plane PP11 of the profile of the branch 104 in the plane Pll.

The die assembly 193 has a profile coinciding with the projection in the plane PP11 of the profile of the contact surface 181 in the plane Pll. The die assembly 193 has a profile coinciding with the projection in the plane PP11 of the profile of the engagement portion 137 in the plane Pll. The die assembly 193 has a profile coinciding with the projection in the plane PP11 of the profile of the ends 107 and 108 in the plane Pll.

The plane Pll is the plane along which the branch 103 extends. The plane PP11 is parallel to the axis A12. The axis AE11 is perpendicular to the axis A12.

In particular, the arm 101 is extruded along the axis AE11 parallel to the axis All and then cut along cutting planes that are oblique with respect to the axis All. The cutting planes are parallel to the plane Pll. Between the extrusion step and the cutting step, a step of thermal treatment is carried out, as described above for the arm 1.

In greater detail, the central body 102, the branch 103, and the branch 104 are obtained with separate extrusions and then joined together via the fixing means 170, 171, 172, and 173.

The central body 102 is obtained via a step of extrusion along the axis AE11 to obtain an extruded profile, which is subsequently cut along cutting planes that are oblique with respect to the axis AE11. The connection opening 109 is obtained via extrusion. The lightening openings 114 are obtained via extrusion.

The branch 103 is obtained via a step of extrusion along the axis AE11, preferably perpendicular to the axis A12, to obtain an extruded profile, which is subsequently cut in planes that are oblique with respect to the extrusion axis AE11.

The branch 104 is obtained via a step of extrusion along the axis AE11, preferably perpendicular to the axis A13, to obtain an extruded profile, which is subsequently cut along cutting planes that are oblique with respect to the extrusion axis AE11.

Between the extrusion steps and the cutting steps, the extruded profiles are heat treated, as described above for the arm 1.

The connection openings 115 and 116 are obtained via a perforating step following upon the extrusion step.

Thanks to cutting in planes that are oblique with respect to the axis AE11 a central portion 102 having a length greater than the diameter of the mouth of the extruder can be obtained. In particular, the arm 101 is used as lower arm of the suspension. The opening 118 is obtained via extrusion. The connection holes 160, 161, 162, and 163 are obtained via a step of perforating following upon the extrusion step.

The engagement portions 134, 135, 136, and 137 are obtained via the extrusion step.

The connection holes 190 are obtained following upon the extrusion step.

With reference to Figures 5 and 6, designated by the number 201 is an arm obtained according to an embodiment alternative to the arm 101 illustrated in Figures 3 and 4. The arm 201 comprises a central body 202 and a front branch 203 and a rear branch 204, both removably connected to the central body 202 through fixing means 270 and 271. The central body 202 extends in a plane P21. The branches 203 and 204 extend in a plane P22. The central body 202 has one end 220 and comprises a preferably cylindrical hollow element 210, having a connection opening 209 that develops along an axis A21 and is configured for receiving a ball joint (not illustrated in the attached figures) . The central body 202 comprises two outer surfaces 232 and 233. The outer surfaces 232 and 233 are smooth.

The branch 203 extends from an end 205 to an end 206. The branch 203 is connected to the central body 202 at the end 205. The branch 203 comprises a connection surface 280 at the end 205. The connection surface 280 is smooth so that it can be coupled to the outer surface 232 of the central body 202.

The branch 204 extends from an end 207 to an end 208. The branch 204 is connected to the central body 202 at the end 207. The branch 204 comprises a connection surface 281 at the end 207. The connection surface 281 is smooth so that it can be coupled to the outer surface 233 of the central body 202. Each branch 203 and 204 comprises a respective connection opening 215 and 216 obtained along each end 206 and 208, respectively .

The connection openings 215 and 216 develop along respective axes A22 and A23. In the non-limiting example represented in Figures 5 and 6 of the present invention, the axes A22 and A23 coincide. The axes A22 and A23 are parallel to the plane P22 or lie in the plane P22. In particular, in the non-limiting example shown in Figures 5 and 6 of the present invention, the axes A22 and A23 lie in the plane P22.

Furthermore, the branches 203 and 204 develop in length transversely with respect to the axes A22 and A23, in particular perpendicular to the axes A22 and A23. Furthermore, the axis A21 develops in a direction transverse to the axes A22 and A23, in particular in a direction perpendicular to the direction of the axes A22 and A23. The axis A21 is transverse to the plane P22 when the branches 203 and 204 are connected to the central body 202.

The branch 203 comprises two connection holes 260 and 261 made in the end 205. The branch 204 comprises two connection holes 264 and 265 made in the end 207. The central body 202 comprises two holes 262 and 263 along respective axes A24 and A25 that, in use, are aligned with the holes 260, 264 and 264, 261, respectively, for housing the respective fixing means 270 and 271, which connect the branch 203, the central body 202, and the branch 204 together.

In particular, the fixing means 270, 271 are screws or bolts.

With reference to Figure 6, the branch 203 and the branch 204 develop in the plane P22. The plane P22 comprises the axes A22 and A23 and is transverse to the axis A21. The central portion 202 comprises a flange 251 for connecting one end of a shock absorber. The flange 251 extends in part in a direction parallel to the axis A21. The flange 251 comprises an opening 252 along an axis A26 parallel to the axes A24 and A25.

The arm 201 is obtained via a process that comprises various steps of extrusion along the axis AE21 and the axis AE22 and steps of cutting of the extruded materials along cutting planes perpendicular to the axes AE21 and AE22. The axis AE21 is parallel to the axes A24, A25 and A26. The axis AE22 is perpendicular to the plane P22. In a preferred embodiment of the present invention, the arm 201 is made of aluminium. In other embodiments of the present invention, the arm 201 is made of other metal alloys. In a preferred embodiment of the present invention, the arm 201 is made of aluminium alloy, preferably series 6000 aluminium, in particular EN AW 6005A, or an alloy of the same family. The arm 201 is obtained via three extrusion steps with respective three porthole-die assemblies 291, 292 and 293, for the central body 202, the branch 203, and the branch 204, respectively. The die assembly

291 is illustrated in Figure 5. The porthole-die assemblies

292 and 293 are represented in Figure 6 set on top of one another. Furthermore, the three porthole-die assemblies 291, 292, and 293 may comprise generically a mandrel and a die (not illustrated) like the die assembly 91.

The die assembly 291 is used to obtain an extruded profile, from which a plurality of central bodies 202 are obtained.

The die assembly 291 extends in a plane PP21 perpendicular to the axes A24, A25 and A26.

The die assembly 291 is a die that has a profile coinciding with the projection in the plane PP21 of the profile of the central body 202 in the plane P21. The die assembly 291 has a profile coinciding with the projection in the plane PP21 of the profile of the outer surfaces 232 and 233 in the plane P21.

The die assembly 291 has a profile coinciding with the projection in the plane PP21 of the profile of the connection holes 262 and 263 in the plane P21.

The die assembly 292 is used to obtain an extruded profile, from which a plurality of branches 203 are obtained.

With reference to Figure 6, designated by PP22 is a plane of extension of the die assembly 292 and 293. The plane PP22 is parallel to the plane P22.

The die assembly 292 has a profile coinciding with the projection in the plane PP22 of the profile of the branch 203 in the plane P22.

The die assembly 292 has a profile coinciding with the projection in the plane PP22 of the profile of the contact surface 280 in the plane P22. The die assembly 292 has a profile coinciding with the projection in the plane PP22 of the profile of the ends 205 and 206 in the plane P22.

The die assembly 293 is used to obtain an extruded profile, from which a plurality of branches 204 are obtained.

The die assembly 293 has a profile coinciding with the projection in the plane PP22 of the profile of the branch 204 in the plane P22.

The die assembly 293 has a profile coinciding with the projection in the plane PP22 of the profile of the contact surface 281 in the plane P22. The die assembly 293 has a profile coinciding with the projection in the plane PP22 of the profile of the ends 207 and 208 in the plane P22.

In particular, the central body 202 is extruded along an axis AE21 of extrusion that is perpendicular to the axis A21. In greater detail, the central body 202 is produced via a step of extrusion along the axis AE21 that is parallel to the axes A24, A25, and A26. The plane PP21 is perpendicular to the extrusion axis AE21. The central body 202 has a curved shape with respect to the plane P22 when it is connected to the branches 203 and 204. The curved shape is obtained thanks to the extrusion obtained along the axis AE21.

The connection opening 209 is obtained via a perforating step following upon the extrusion step. In addition, the branch 203 is obtained via a step of extrusion along an axis AE22 of extrusion that is perpendicular to the axis A22. The plane PP22 is perpendicular to the axis AE22. In addition, the axes AE22 and A22 are perpendicular to one another. Moreover, the axes AE22 and AE23 are perpendicular to one another. Furthermore, the branch 204 is obtained via an extrusion step with the axis AE22 of extrusion perpendicular to the axis A23.

The process envisages a step of cutting, following upon the extrusion step, of the respective extruded profile of the central body 202, the branch 203, and the branch 204 along cutting planes perpendicular to the respective extrusion axes AE21 and AE22.

The production process envisages obtaining the central body 202, the branch 203, and the branch 204 through three extrusion steps and subsequent distinct cutting steps, as illustrated above, followed by connection together thereof using the fixing means 270 and 271. The production process envisages the step of heat treating each extruded profile after the extrusion step and prior to the cutting step, as illustrated above for the arm 1. In particular, the arm 201 is used as lower arm of the suspension. The connection holes 262 and 263 are obtained via extrusion .

The sphere of protection of the present invention extends to a method of producing a suspension comprising an arm according to any one of the foregoing embodiments and to the suspension comprising an arm according to any one of the foregoing embodiments .

Finally, it is evident that modifications and variations may be made to the method and to the arm described herein according to various embodiments, without thereby departing from the scope of the annexed claims.