Method of manufacturing a motor vehicle frame assembly

A method of manufacturing a frame assembly for a motor vehicle, comprising the steps of

• (A) forming from a sheet of metallic material a rearward frame module having a pair of laterally spaced, longitudinally extending rear frame siderails, each of said rear frame siderails having a generally U-shaped transverse cross section including a rear siderail base portion and a pair of rear siderail leg portions extending in generally parallel relation to one another from opposite transverse ends of said rear siderail base portion, the rear siderail base portion having a greater length between said transverse ends at a forward portion thereof relative to the length between said transverse ends at a rearward portion thereof, said rear frame siderails each being formed by
• i) placing said sheet of metallic material between cooperative stamping dies, and
• ii) compressively engaging opposite sides of said sheet with said stamping dies so as to provide said sheet with said U-shaped transverse cross section;
• B) forming from a sheet of metallic material a central frame module having a pair of laterally spaced, longitudinally extending central frame siderails, each of said central frame siderails having a generally U-shaped transverse cross section including a central siderail base portion and a pair of central siderail leg portions extending in generally parallel relation to one another from opposite transverse ends of said central siderail base portion, each of said central frame siderails being formed by
• i) forming said sheet of metallic material into a longitudinal member having a generally U-shaped transverse cross section including said base portion and said pair of leg portions extending in generally parallel relation to one another from opposite transverse ends of said base portion,
• ii) engaging opposite longitudinal ends of said longitudinal member and pulling said longitudinal ends in opposite directions with respect to the longitudinal extent of said longitudinal member in order to stretch said longitudinal member longitudinally so that the metallic material forming the longitudinal member reaches its yield state, and
• iii) bending said longitudinal member having said U-shaped cross-section at two longitudinally spaced locations so that
• 1) at a first of said locations
• a) said base portion is bent generally within its plane,
• b) one of said leg portions extending from one end of said base portion is stretched, and
• c) an opposite one of said leg portions extending from an opposite end of said base portion is compressed, and so that
• 2) at a second of said locations
• a) said base portion is bent generally within its plane,
• b) said one of the leg portions extending from one end of said base portion is compressed, and
• c) said opposite one of said leg portions extending from an opposite end of said base portion is stretched;
• said longitudinal member thus being bent to conform to the desired configuration of one of said central frame siderails;
• C) forming from a metallic tubular member said forward frame module having a pair of laterally spaced, longitudinally extending tubular forward frame siderails, each of said forward frame siderails being formed by:
• i) placing a metallic tubular member into a cavity of a die mold, said die mold having an interior surface defining a shape of said cavity,
• ii) providing a fluid interiorly to said metallic tubular member with sufficient pressure so as to expand said tubular member outwardly into peripheral engagement with said interior surface of said die mold to substantially conform said tubular member to the shape of said cavity,
• iii) applying force to opposite ends of said tubular member so as to cause said ends to be moved generally inwardly towards an intermediate portion of said tubular member while said tubular member is being expanded so as to maintain a wall thickness of said tubular member within a specified range;
• and
• D) rigidly securing said rearward frame module and said forward frame module to opposite respective ends of said central frame module by
• i) securing rearward portions of said forward frame siderails to forward portions of said central frame siderails, and
• ii) securing said forward portions of the rearward frame siderails, each having said base portion with said relatively greater length between transverse ends, to rearward portions of said central frame siderails.

A method of manufacturing a frame assembly for a motor vehicle, comprising the steps of:

• forming a rearward frame module having a pair of laterally spaced elongated rearward frame siderails extending in the fore-aft direction;
• forming a forward frame module having a pair of laterally spaced elongated forward frame siderails extending in the fore-aft direction of the frame assembly;
• forming a central frame module comprising a pair of longitudinal central frame siderails, each of said central frame siderails being constructed by
• i) bending an elongate planar sheet of metallic material transversely within its plane
• ii) placing said planar sheet of metallic material between cooperative stamping dies after is has been bent within its plane;
• iii) compressively engaging opposite sides of said planar sheet with said stamping dies so as to form said sheet into a longitudinal member having a generally U-shaped transverse cross section;
• and
• rigidly securing said forward frame module and said rearward frame module to opposite ends of said central frame module by
• 1) securing a forward end of each of said central frame siderails with a rear end of a respective one of said forward frame siderails;
• and
• 2) securing a rearward end of each of said central frame siderails with a front end of a respective one of said rear frame siderails.

A method of manufacturing a frame assembly for a motor vehicle, comprising the steps of

• (a) forming from an elongated sheet of metallic material a rearward frame module having a pair of laterally spaced, longitudinally extending rear frame siderails, each of said rear frame siderails having a generally U-shaped transverse cross section including a rear siderail base portion and a pair of rear siderail leg portions extending in generally parallel relation to one another from opposite transverse ends of said rear siderail base portion, the rear siderail base portion having a greater length between said transverse ends at a forward portion thereof relative to the length between said transverse ends at a rearward portion thereof, said rear frame siderails each being formed by
• (i) placing said sheet of metallic material between cooperative stamping dies;
• and
• ii) compressively engaging opposite sides of said sheet with said stamping dies so as to provide said sheet with said U-shaped transverse cross section;
• (b) forming from a planar sheet of metallic material a central frame module having a pair of laterally spaced, longitudinally extending central frame siderails, each of said central frame siderails having a generally U-shaped transverse cross section including a central siderail base portion and a pair of central siderail leg portions extending in generally parallel relation to one another from opposite transverse ends of said central siderail base portion, each of said central frame siderails being formed by
• (i) bending said elongated planar sheet of metallic material transversely within its plane
• (ii) placing said planar sheet of metallic material between cooperative stamping dies after is has been bent within its plane;
• (iii) compressively engaging opposite sides of said planar sheet with said stamping dies so as to form said sheet into a longitudinal member having a generally U-shaped transverse cross section;
• and
• (c) forming from a metallic tubular member a forward frame module having a pair of laterally spaced, longitudinally extending tubular forward frame siderails, each of said forward frame siderails being formed by:
• (i) placing said metallic tubular member into a cavity of a die mold, said die mold having an interior surface defining a shape of said cavity,
• (ii) providing a fluid interiorly to said metallic tubular member with sufficient pressure so as to expand said tubular member outwardly into peripheral engagement with said interior surface of said die mold to substantially conform said tubular member to the shape of said cavity,
• (iii) applying force to opposite ends of said tubular member so as to cause said ends to be moved generally inwardly towards an intermediate portion of said tubular member while said tubular member is being expanded so as to maintain a wall thickness of said tubular member within a specified range, and
• (d) rigidly securing said rearward frame module and said forward frame module to opposite respective ends of said central frame module by
• (i) securing rearward portions of said forward frame siderails to forward portions of said central frame siderails, and
• (ii) securing said forward portions of the rearward frame siderails, each having said base portion with said relatively greater length between transverse ends, to rearward portions of said central frame siderails.

A method of manufacturing a frame assembly for a motor vehicle, comprising the steps of

• (A) forming from a sheet of metallic material a rearward frame module having a pair of laterally spaced, longitudinally extending rear frame siderails, each of said rear frame siderails having a generally U-shaped transverse cross section including a rear siderail base portion and a pair of rear siderail leg portions extending in generally parallel relation to one another from opposite transverse ends of said rear siderail base portion, the rear siderail base portion having a greater length between said transverse ends at a forward portion thereof relative to the length between said transverse ends at a rearward portion thereof, said rear frame siderails each being formed by
• i) placing said sheet of metallic material between cooperative stamping dies, and
• ii) stamping said sheet with said stamping dies so as to provide said sheet with said U-shaped transverse cross section
• B) forming from a sheet of metallic material a central frame module having a pair of laterally spaced, longitudinally extending central frame siderails, each of said central frame siderails having a generally U-shaped transverse cross section including a central siderail base portion and a pair of central siderail leg portions extending in generally parallel relation to one another from opposite transverse ends of said central siderail base portion, each of said central frame siderails being formed by
• i) forming said sheet of metallic material into a longitudinal member having a generally U-shaped transverse cross section including said base portion and said pair of leg portions extending in generally parallel relation to one another from opposite transverse ends of said base portion,
• ii) bending said longitudinal member having said U-shaped cross-section at two longitudinally spaced locations so that
• 1) at a first of said locations
• a) said base portion is bent generally within its plane,
• b) one of said leg portions extending from one end of said base portion is provided with a concave exterior surface, and
• c) an opposite one of said leg portions extending from an opposite end of said base portion is provided with a convex exterior surface, and so that
• 2) at a second of said locations
• a) said base portion is bent generally within its plane,
• b) said one of the leg portions extending from one end of said base portion is provided with a convex exterior surface, and
• c) said opposite one of said leg portions extending from an opposite end of said base portion is provided with a concave exterior surface, said longitudinal member thus being bent to conform to the desired configuration of one of said central frame siderails;
• C) forming from a metallic tubular member said forward frame module having a pair of laterally spaced, longitudinally extending tubular forward frame siderails, each of said forward frame siderails being formed by:
• i) placing a metallic tubular member into a cavity of a die mold, said die mold having an interior surface defining a shape of said cavity,
• ii) providing a fluid interiorly to said metallic tubular member with sufficient pressure so as to expand said tubular member outwardly into peripheral engagement with said interior surface of said die mold to substantially conform said tubular member to the shape of said cavity,
• iii) applying force to opposite ends of said tubular member so as to cause said ends to be moved generally inwardly towards an intermediate portion of said tubular member while said tubular member is being expanded so as to maintain a wall thickness of said tubular member within a specified range;
• and
• D) rigidly securing said rearward frame module and said forward frame module to opposite respective ends of said central frame module by
• i) securing rearward portions of said forward frame siderails to forward portions of said central frame siderails, and
• ii) securing said forward portions of the rearward frame siderails, each having said base portion with said relatively greater length between transverse ends, to rearward portions of said central frame siderails.