Patent Application
20130061437
The present invention relates to a method for manufacturing a method for manufacturing a motor vehicle door hinge from a steel plate blank having predetermined thickness, width, and height using cold heading or punching and, in particular, to a technology relating to a method for manufacturing a motor vehicle door hinge having a sufficient strength at low manufacturing cost by forming, at one end of the blank in the width direction, a cylindrical bulging portion having a horizontal cross section of a circular or elliptical shape and extending in the height direction by cold heading and forming, in the cylindrical bulging portion, a shaft hole along the center axis of the cylindrical bulging portion, where the shaft hole allows a hinge pin to be inserted thereinto using a special die and a special punch so that the height of the shaft hole is twice or more the diameter of the shaft hole.
Existing motor vehicle door hinges are manufactured from a sheet metal since motor vehicle door hinges can be manufactured by using, for example, press forming at low cost (refer to, for example, PTL 1).
Alternatively, since the strength of existing motor vehicle door hinges formed from a sheet metal is low, door hinges of full-sized cars and high-end cars are manufactured from a mold steel. At that time, a mold steel formed through an extrusion process is used and is cut into pieces each having a desired length. The piece is formed into a desired shape through a cutting work (refer to, for example, PTL 2).
The sheet metal motor vehicle door hinge described in PTL 1 has a bend portion with a small thickness. In addition, a large bending moment acts on the bend portion. Accordingly, damage of the door hinge easily occurs due to an impact caused by opening and closing of the door.
Furthermore, since a hinge shaft that connects a door-side door hinge to a chassis-side door hinge is disposed so as to be exposed to the outside, the hinge shaft is mostly stressed when the door is rotated and, therefore, damage of the door hinge easily occurs.
As described above, although a sheet metal motor vehicle door hinge is manufactured at low cost, the strength is low, which is problematic.
In addition, the motor vehicle door hinge formed through a cutting work described in PTL 2 has a sufficient strength. However, the manufacturing cost of the mold steel formed through an extrusion process is high. In addition, the cost of the cutting process is high. Therefore, the total cost is high, which is problematic.
Accordingly, the present invention is intended to solve such problems arising in the existing structure. An object of the present invention is to provide a method for manufacturing a motor vehicle door hinge having a sufficient strength from a steel plate blank by, for example, cold heading and punching at low manufacturing cost.
According to Claim 1 of the present invention, a method for manufacturing a motor vehicle door hinge from a steel plate blank having predetermined thickness, width, and height using processes including cold heading and punching is provided.
The method includes a cold heading step of forming, at one end of the blank in the width direction, a cylindrical bulging portion having a cylindrical bulging shape bulging in the thickness direction so as to have a horizontal cross section of a circular shape or an elliptical shape and extending in the height direction by cold heading,
a shaft hole forming step of forming a shaft hole that passes through the cylindrical bulging portion along the shaft axis using a first punch and a first die, the shaft hole allowing a hinge pin to pass therethrough, and
a shaft hole finishing step of punching the shaft hole formed in the shaft hole forming step from the end at which machining of the first punch ends using a second punch and a second die.
A height of the cylindrical bulging portion of the shaft hole formed in the shaft hole forming step is twice or more a diameter of the shaft hole.
The first punch used in the shaft hole forming step has a top end having a shape of a cone with a cone angle in the range from 70° to 120°.
The first die has an inner wall having a gap relative to an outer circumferential surface of the cylindrical bulging portion of the blank, and the size of a gap volume formed by the outer circumferential surface of the cylindrical bulging portion and the inner wall is set so that when the first punch punches the cylindrical bulging portion of the blank, a hole portion formed from the end at which machining of the first punch starts to a predetermined length position does not produce a punched slug, the cylindrical bulging portion bulges outward, and a hole portion from the predetermined length position to the end at which the machining of the first punch ends produces a punched slug to be ejected.
The second die has a shape substantially the same as the shape of the first die.
The second punch has a top end having a shape of a truncated cone or a cone with a cone angle in the range from 70° to 120° and the largest diameter that is larger than that of the first punch by 0.1 mm to 0.3 mm.
According to Claim 2 of the present invention, a method for manufacturing a motor vehicle door hinge from a steel plate blank having predetermined thickness, width, and height using processes including cold heading and punching is provided.
The method includes a cold heading step of forming, at one end of the blank in the width direction, a protrusion attached cylindrical bulging portion having a protrusion attached cylindrical bulging shape that bulges in the thickness direction so as to have a horizontal cross section of a circular shape or an elliptical shape and that extends in the height direction and having a protrusion on the top end of the circular shape by cold heading, where the protrusion serves as a door stopper,
a shaft hole forming step of forming a shaft hole that passes through the cylindrical bulging portion along the shaft axis using a first punch and a first die, where the shaft hole allows a hinge pin to pass therethrough, and
a shaft hole finishing step of punching the shaft hole formed in the shaft hole forming step from the end at which machining of the first punch ends using a second punch and a second die.
The first punch used in the shaft hole forming step has a top end having a shape of a cone with a cone angle in the range from 70° to 120°.
The height of the protrusion attached cylindrical bulging portion of the shaft hole formed in the shaft hole forming step is twice or more a diameter of the shaft hole.
The first die has an inner wall having a gap relative to an outer circumferential surface of the protrusion attached cylindrical bulging portion of the blank. The size of a gap volume formed by the outer circumferential surface of the protrusion attached cylindrical bulging portion and the inner wall is set so that when the first punch punches the protrusion attached cylindrical bulging portion of the blank, a hole portion formed from an end at which machining of the first punch starts to a predetermined length position does not produce a punched slug and the protrusion attached cylindrical bulging portion bulges outward and a hole portion from the predetermined length position to the end at which the machining of the first punch ends produces a punched slug to be ejected.
The second die has a shape substantially the same as the shape of the first die, and
the second punch has a top end having a shape of a truncated cone or a cone with a cone angle in the range from 70° to 120° and the largest diameter that is larger than that of the first punch by 0.1 mm to 0.3 mm.
According to Claim 3 of the present invention, in addition to the configuration according to Claim 1 or 2 of the present invention, the method for manufacturing a motor vehicle door hinge includes an annealing step of performing one of spheroidizing annealing and soft annealing on the blank after the cold heading step and before the shaft hole forming step.
The shaft hole forming step is performed by cold working.
According to Claim 4 of the present invention, in addition to the configuration according to Claim 1 or 2 of the present invention, in the shaft hole forming step of the method for manufacturing a motor vehicle door hinge, one of the cylindrical bulging portion and the protrusion attached cylindrical bulging portion is subjected to warm working at a temperature in the range from 450° C. to 900° C.
According to Claim 5 of the present invention, in addition to the configuration according to any one of Claims 1 to 4 of the present invention, the method for manufacturing a motor vehicle door hinge further includes a wall thickness increasing step of sandwiching one of the cylindrical bulging portion and the protrusion attached cylindrical bulging portion formed at one end of the blank by a split mold die having a back clearance that allows the middle portion of the blank to bulge in the thickness direction so that the other end protrudes from the split mold die and increasing a wall thickness of the middle portion of the blank by pressing the other end of the blank using a punch and
a bending step of bending a thick-wall portion of the blank formed in the wall thickness increasing step into an L shape using press working. The shaft hole forming step and the shaft hole finishing step are performed after the wall thickness increasing step is performed. After the shaft hole finishing step is performed, the bending step is performed.
According to Claim 6 of the present invention, in addition to the configuration according to any one of Claims 1 to 5 of the present invention, the method for manufacturing a motor vehicle door hinge further includes a bending step of bending the middle portion of the blank into an L shape after the shaft hole finishing step is performed and
a hole forming step of forming a hole in a flat portion of the blank without having the shaft hole formed therein by punching after the bending step is performed. The hole is used for attaching the motor vehicle door hinge to one of a vehicle body and a door.
According to Claim 7 of the present invention, a method for manufacturing a motor vehicle door hinge includes assembling the chassis-side door hinge that is to be attached to a vehicle body and that is manufactured by the method according to Claim 6 and the door-side door hinge that is to be attached to a door and that is manufactured by the method according to Claim 6 into a pair of motor vehicle door hinges by inserting a tubular plastic shock-absorbing member into the shaft hole of each of the door hinges, inserting a head hinge pin into the two tubular plastic shock-absorbing members and a washer so that the hinge pin penetrates the tubular plastic shock-absorbing members and the washer, and caulking an end of the head hinge pin.
According to Claim 8 of the present invention, a method for manufacturing a motor vehicle door hinge by manufacturing a first member from a first steel plate blank having predetermined thickness, width, and height by processes including cold heading and punching, manufacturing a second member having a polygonal plate shape with a size in the height direction larger than the height of the first blank from a second steel plate blank by punching, and integrating the first member with the second member is provided.
The method includes a cold heading step of forming, at one end of the first blank in the width direction, a protrusion attached cylindrical bulging portion having a protrusion attached cylindrical bulging shape that bulges in the thickness direction so as to have a horizontal cross section of a circular shape or an elliptical shape and that extends in the height direction and having a protrusion on the top end of the circular shape or the elliptical shape by cold heading, where the protrusion serves as a door stopper,
a shaft hole forming step of forming a shaft hole that passes through the protrusion attached cylindrical bulging portion along the shaft axis using a first punch and a first die, where the shaft hole allows a hinge pin to pass therethrough,
a shaft hole finishing step of punching the shaft hole formed in the shaft hole forming step from the end at which machining of the first punch ends using a second punch and a second die so that the first member is manufactured,
forming, in the second blank, a quadrilateral hole for receiving an end of the first member opposite to the shaft hole and two holes used for attaching the motor vehicle door hinge to a vehicle body by punching and locating one of the two hole at a horizontal position that is the same as a horizontal position of the quadrilateral hole and the other hole below or above the quadrilateral hole so that the second member is manufactured, and
assembling the first member and the second member into a chassis-side door hinge to be attached to the vehicle body by inserting the end of the first member opposite to the shaft hole into the quadrilateral hole of the second member and caulking the end.
The first punch used in the shaft hole forming step has a top end having a shape of a cone with a cone angle in the range from 70° to 120°. A height of the protrusion attached cylindrical bulging portion of the shaft hole formed in the shaft hole forming step is twice or more a diameter of the shaft hole. The first die has an inner wall having a gap relative to an outer circumferential surface of the protrusion attached cylindrical bulging portion of the blank. The size of a gap volume formed by the outer circumferential surface of the protrusion attached cylindrical bulging portion and the inner wall is set so that when the first punch punches the protrusion attached cylindrical bulging portion of the blank, a hole portion formed from an end at which machining of the first punch starts to a predetermined length position does not produce a punched slug and the protrusion attached cylindrical bulging portion bulges outward and a hole portion from the predetermined length position to the end at which the machining of the first punch ends produces a punched slug to be ejected. The second die has a shape substantially the same as the shape of the first die. The second punch has a top end having a shape of a truncated cone or a cone with a cone angle in the range from 70° to 120° and the largest diameter that is larger than that of the first punch by 0.1 mm to 0.3 mm.
According to Claim 9 of the present invention, in addition to the configuration according to Claim 8 of the present invention, the method for manufacturing a motor vehicle door hinge further includes forming a stepped portion having a small horizontal cross section at the end of the first member opposite to the shaft hole so as to have a size that is longer than the thickness of the second member by a predetermined value,
forming the quadrilateral hole of the second member so that the quadrilateral hole on an insertion side has a shape that mates with the stepped portion of the first member and the quadrilateral hole on the vehicle body side has a taper that flares outward, and
integrating the first member with the second member by inserting the stepped portion of the first member into the quadrilateral hole and performing a caulking process so that an end surface of the stepped portion is flush with a surface of the second member on the vehicle body side.
According to Claim 10 of the present invention, a method for manufacturing a motor vehicle door hinge includes assembling the door-side door hinge that is to be attached to a door and that is manufactured by the method according to Claim 6 and the chassis-side door hinge that is to be attached to a vehicle body and that is manufactured by the method according to Claim 9 into a pair of motor vehicle door hinges by inserting a tubular plastic shock-absorbing member into the shaft hole of each of the door hinges, inserting a head hinge pin into the two tubular plastic shock-absorbing members and a washer so that the hinge pin penetrates the tubular plastic shock-absorbing members and the washer, and caulking an end of the head hinge pin.
According to Claim 1 of the present invention, the method for manufacturing a motor vehicle door hinge includes a cold heading step of forming, at one end of the blank in the width direction, a cylindrical bulging portion having a cylindrical bulging shape bulging in the thickness direction so as to have a horizontal cross section of a circular shape or an elliptical shape and extending in the height direction by cold heading, a shaft hole forming step of forming a shaft hole that passes through the cylindrical bulging portion along the shaft axis using a first punch and a first die, where the shaft hole allows a hinge pin to pass therethrough, and a shaft hole finishing step of punching the shaft hole formed in the shaft hole forming step from the end at which machining of the first punch ends using a second punch and a second die. In particular, the first punch used in the shaft hole forming step has a top end having a shape of a cone with a cone angle in the range from 70° to 120°. The first die has an inner wall having a gap relative to an outer circumferential surface of the cylindrical bulging portion of the blank, and the size of a gap volume formed by the outer circumferential surface of the cylindrical bulging portion and the inner wall is set so that when the first punch punches the cylindrical bulging portion of the blank, a hole portion formed from the end at which machining of the first punch starts to a predetermined length position does not produce a punched slug, the cylindrical bulging portion bulges outward, and a hole portion from the predetermined length position to the end at which the machining of the first punch ends produces a punched slug to be ejected. Accordingly, an advantage that the shaft hole having a height that is twice or more the diameter of the shaft hole can be processed by punching is provided. Thus, by performing, for example, cold heading and punching on a steel plate blank, a motor vehicle door hinge having a sufficient strength can be manufactured at low cost.
According to Claim 2 of the present invention, the method for manufacturing a motor vehicle door hinge includes a cold heading step of forming, at one end of the blank in the width direction, a protrusion attached cylindrical bulging portion having a protrusion attached cylindrical bulging shape that bulges in the thickness direction so as to have a horizontal cross section of a circular shape or an elliptical shape and that extends in the height direction and having a protrusion on the top end of the circular shape by cold heading, where the protrusion serves as a door stopper, a shaft hole forming step of forming a shaft hole that passes through the cylindrical bulging portion along the shaft axis using a first punch and a first die, where the shaft hole allows a hinge pin to pass therethrough, and a shaft hole finishing step of punching the shaft hole formed in the shaft hole forming step from the end at which machining of the first punch ends using a second punch and a second die. In particular, the first punch used in the shaft hole forming step has a top end having a shape of a cone with a cone angle in the range from 70° to 120°. The first die has an inner wall having a gap relative to an outer circumferential surface of the protrusion attached cylindrical bulging portion of the blank. The size of a gap volume formed by the outer circumferential surface of the protrusion attached cylindrical bulging portion and the inner wall is set so that when the first punch punches the protrusion attached cylindrical bulging portion of the blank, a hole portion formed from an end at which machining of the first punch starts to a predetermined length position does not produce a punched slug and the protrusion attached cylindrical bulging portion bulges outward and a hole portion from the predetermined length position to the end at which the machining of the first punch ends produces a punched slug to be ejected. Accordingly, the shaft hole having a height that is twice or more the diameter of the shaft hole can be processed by punching is provided. Thus, an advantage that by performing, for example, cold heading and punching on a steel plate blank, a motor vehicle door hinge having a sufficient strength can be manufactured at low cost is provided.
According to Claim 3 of the present invention, the method for manufacturing a motor vehicle door hinge includes an annealing step of performing one of spheroidizing annealing and soft annealing on the blank after the cold heading step and before the shaft hole forming step. The shaft hole forming step is performed by cold working. Accordingly, an advantage that a shaft hole can be highly accurately formed is provided in addition to the advantage of Claim 1 or 2 of the present invention.
According to Claim 4 of the present invention, in the shaft hole forming step of the method for manufacturing a motor vehicle door hinge, one of the cylindrical bulging portion and the protrusion attached cylindrical bulging portion is subjected to warm working at a temperature in the range from 450° C. to 900° C. Accordingly, an advantage that the size of the process machinery, such as a press machine, can be reduced is provided in addition to the advantage of Claim 1 or 2 of the present invention. Furthermore, the lifetime of the tool can be increased.
According to Claim 5 of the present invention, the method for manufacturing a motor vehicle door hinge further includes a wall thickness increasing step of sandwiching one of the cylindrical bulging portion and the protrusion attached cylindrical bulging portion formed at one end of the blank by a split mold die having a back clearance that allows the middle portion of the blank to bulge in the thickness direction so that the other end protrudes from the split mold die and increasing a wall thickness of the middle portion of the blank by pressing the other end of the blank using a punch and a bending step of bending a thick-wall portion of the blank formed in the wall thickness increasing step into an L shape using press working. The shaft hole forming step and the shaft hole finishing step are performed after the wall thickness increasing step is performed. After the shaft hole finishing step is performed, the bending step of bending the thick-wall portion of the blank formed in the wall thickness increasing step into an L shape by press working is performed. Accordingly, since the bending portion is formed as a thick-wall portion in the wall thickness increasing step, an advantage that the strength of the bending portion can be increased is provided in addition to the advantage of any one of Claims 1 to 4 of the present invention.
According to Claim 6 of the present invention, the method for manufacturing a motor vehicle door hinge further include a bending step of bending the middle portion of the blank into an L shape after the shaft hole finishing step is performed and a hole forming step of forming a hole in a flat portion of the blank without having the shaft hole formed therein by punching after the bending step is performed. The hole is used for attaching the motor vehicle door hinge to one of a vehicle body and a door. Accordingly, an advantage that a bending portion and a hole can be efficiently formed is provided in addition to the advantage of any one of Claims 1 to 5 of the present invention.
According to Claim 7 of the present invention, the method for manufacturing a motor vehicle door hinge includes assembling the chassis-side door hinge that is to be attached to a vehicle body and that is manufactured by the method according to Claim 6 and the door-side door hinge that is to be attached to a door and that is manufactured by the method according to Claim 6 into a pair of motor vehicle door hinges by inserting a tubular plastic shock-absorbing member into the shaft hole of each of the door hinges, inserting a head hinge pin into the two tubular plastic shock-absorbing members and a washer so that the hinge pin penetrates the tubular plastic shock-absorbing members and the washer, and caulking an end of the head hinge pin. Accordingly, an advantage that a pair of motor vehicle door hinges can be simply manufactured is provided in addition to the advantage of Claim 6 of the present invention.
According to Claim 8 of the present invention, the method for manufacturing a motor vehicle door hinge by manufacturing a first member from a first steel plate blank having predetermined thickness, width, and height by processes including cold heading and punching, manufacturing a second member having a polygonal plate shape with a size in the height direction larger than the height of the first blank from a second steel plate blank by punching, and integrating the first member with the second member is provided. The method includes a cold heading step of forming, at one end of the first blank in the width direction, a protrusion attached cylindrical bulging portion having a protrusion attached cylindrical bulging shape that bulges in the thickness direction so as to have a horizontal cross section of a circular shape or an elliptical shape and that extends in the height direction and having a protrusion on the top end of the circular shape or the elliptical shape by cold heading, where the protrusion serves as a door stopper, a shaft hole forming step of forming a shaft hole that passes through the protrusion attached cylindrical bulging portion along the shaft axis using a first punch and a first die, where the shaft hole allows a hinge pin to pass therethrough, a shaft hole finishing step of punching the shaft hole formed in the shaft hole forming step from the end at which machining of the first punch ends using a second punch and a second die. In this way, the first member is manufactured. In particular, the first punch used in the shaft hole forming step has a top end having a shape of a cone with a cone angle in the range from 70° to 120°. The first die has an inner wall having a gap relative to an outer circumferential surface of the protrusion attached cylindrical bulging portion of the blank. The size of a gap volume formed by the outer circumferential surface of the protrusion attached cylindrical bulging portion and the inner wall is set so that when the first punch punches the protrusion attached cylindrical bulging portion of the blank, a hole portion formed from an end at which machining of the first punch starts to a predetermined length position does not produce a punched slug and the protrusion attached cylindrical bulging portion bulges outward and a hole portion from the predetermined length position to the end at which the machining of the first punch ends produces a punched slug to be ejected. Furthermore, in the second blank, a quadrilateral hole for receiving an end of the first member opposite to the shaft hole and two holes used for attaching the motor vehicle door hinge to a vehicle body are formed by punching. One of the two holes is disposed at a horizontal position that is the same as a horizontal position of the quadrilateral hole, and the other hole is disposed below or above the quadrilateral hole. In this way, the second member is manufactured. Thereafter, the first member and the second member are assembled into a chassis-side door hinge to be attached to the vehicle body by inserting the end of the first member opposite to the shaft hole into the quadrilateral hole of the second member and caulking the end. Accordingly, even when an attaching portion of the vehicle body is narrow in the horizontal direction, the second unit can be integrated with the first member by caulking. Therefore, an advantage that the chassis-side door hinge having a complicated structure can be manufactured at low cost is provided.
According to Claim 9 of the present invention, the method for manufacturing a motor vehicle door hinge further includes forming a stepped portion having a small horizontal cross section at the end of the first member opposite to the shaft hole so as to have a size that is longer than the thickness of the second member by a predetermined value, forming the quadrilateral hole of the second member so that the quadrilateral hole on an insertion side has a shape that mates with the stepped portion of the first member and the quadrilateral hole on the vehicle body side has a taper that flares outward, and integrating the first member with the second member by inserting the stepped portion of the first member into the quadrilateral hole and performing a caulking process so that an end surface of the stepped portion is flush with a surface of the second member on the vehicle body side. Accordingly, an advantage that the first member and the second member can be firmly integrated into one body is provided in addition to the advantage of Claim 8 of the present invention.
According to Claim 10 of the present invention, the method for manufacturing a motor vehicle door hinge includes assembling the door-side door hinge that is to be attached to a door and that is manufactured by the method according to Claim 6 and the chassis-side door hinge that is to be attached to a vehicle body and that is manufactured by the method according to Claim 9 into a pair of motor vehicle door hinges by inserting a tubular plastic shock-absorbing member into the shaft hole of each of the door hinges, inserting a head hinge pin into the two tubular plastic shock-absorbing members and a washer so that the hinge pin penetrates the tubular plastic shock-absorbing members and the washer, and caulking an end of the head hinge pin. Accordingly, an advantage that a pair of motor vehicle door hinges can be simply manufactured is provided in addition to the advantages of Claims 6 and 9 of the present invention.
Embodiments of the present invention are described in detail below with reference to the accompanying drawings.
A method for manufacturing a motor vehicle door hinge according to a first embodiment of the present invention is described next with reference to
The processes of the method for manufacturing a motor vehicle door hinge according to a first embodiment is schematically described with reference to a block diagram illustrated in
The processes of the method for manufacturing a motor vehicle door hinge according to a first embodiment include a planarization cutting process 20, a cold heading process 30, a wall thickness increasing process 40, a thin-wall forming process 50, a shape reforming process 60, an annealing process 65, a shaft hole forming process 70, a shaft hole finishing process 80, a bending process 90, and a hole forming process 100.
As illustrated in
The above-described processes 20 to 100 for producing the chassis-side door hinge 1a are described below with reference to
As illustrated in
Subsequently, as illustrated in
The double header machine 31 causes one end of the steel blank 2a in the width direction to bulge outward. As illustrated in a plan view of
The double header machine 31 includes the cold heading die 32 illustrated in
In a first process 30b of the cold heading process 30 performed by the double header machine 31, as illustrated in
Subsequently, in a second process 30c of the cold heading process 30 performed by the double header machine 31, as illustrated in
Thereafter, in a third process 30d of the cold heading process 30, as illustrated in
The cold heading punch 34 applies a pressing force to the cutting surface of the blank 2a such that the cold heading punch 34 is not brought into contact with the cold heading die 32 and performs a cold heading process. As indicated by a perspective view of
Note that since the circumferential direction of the protrusion attached cylindrical bulging portion 4 is the bulging direction of the protrusion portion attached cylindrical bulging portion 4, a burr is negligibly formed.
Subsequently, the wall thickness increasing process 40, the thin-wall forming process 50, the shape reforming process 60, the shaft hole forming process 70, the shaft hole finishing process 80, the bending process 90, and the hole forming process 100 are performed using a 500-ton transfer press machine.
As illustrated in
Through the wall thickness increasing process 40, a thick-wall portion 7 is formed in the middle of the blank 2a. Subsequently, in the bending process 90 (described in more detail below), the thick-wall portion 7 is bent into an L shape.
Thereafter, in the thin-wall forming process 50 illustrated in
In the shape reforming process 60 illustrated in
Before forming a shaft hole 10 that allows a hinge pin to be inserted thereinto along the center axis of the shaft hole 10 in the shaft hole forming process 70, the annealing process 65 (refer to
To perform the annealing process 65, a plurality of the blanks 2a subjected to the shape reforming process 60 are temporarily reserved. If the number of the stored blanks 2a reaches a predetermined value, the blanks 2a are put into a furnace and kept at an annealing temperature immediately above the transformation point. Thereafter, the blanks 2a are slowly-cooled in the furnace.
The shaft hole forming process 70 is described next with reference to
In the shaft hole forming process 70, the shaft hole 10 is formed using a first punch 71 and a first die 72 so as to allow a hinge pin to pass therethrough along the center axis of the protrusion attached cylindrical bulging portion 4 of the blank 2a subjected to the annealing process 65.
The first punch 71 illustrated in
In addition, as illustrated in
In addition, the first die 72 has a positioning portion 72c formed therein. The top end of the protrusion attached cylindrical bulging portion 4 of the blank 2a is brought into contact with the positioning portion 72c. Thus, the outer circumferential surface of the blank 2a is inserted into an inner wall 72d other than a portion that the protrusion attached cylindrical bulging portion 4 faces without any gap therebetween.
Note that
By using the first punch 71, the first die 72, and the 500-ton transfer press machine, the shaft hole 10 is formed along the shaft axis of the protrusion attached cylindrical bulging portion 4.
As illustrated in
Thereafter, the blank 2a is inserted into the first die 72. The upper die set 73 is lowered so that the stripper 73e of the upper die set 73 is brought into contact with the first die 72. Thereafter, the blank 2a except for a portion of the shaft hole 10 formed in the blank 2a is fixed between the stripper 73e and the die folder 74a in the up and down direction by the spring 73f. Thereafter, the first punch 71 is lowered. Thus, the shaft hole 10 is formed. At that time, a hole portion formed from the end at which machining of the first punch 71 starts to ⅘ the length of the blank 2a does not produce a punched slug and the protrusion attached cylindrical bulging portion 4 bulges outward and, thus, the gap volume 72b of the first die 72 is filled with the bulging portion. Thereafter, the hole portion formed from ⅘ the length of the blank 2a to the end at which the machining of the first punch 71 ends produces a punched slug, and the slug is ejected to the outside through a slug ejection port 74d.
Subsequently, the upper die set 73 is raised to the original position, and the blank 2a having the shaft hole 10 formed therein is pushed upward out of the first die 72 by a hydraulic power unit (not illustrated). In this way, the shaft hole forming process 70 is completed.
The blank 2a subjected to the shaft hole forming process 70 in this manner has a protrusion attached tubular bulging portion 4a transformed from the protrusion attached cylindrical bulging portion 4 prior to the shaft hole forming process 70.
The blank 2a subjected to the shaft hole forming process 70 is upset by the transfer press machine, and the shaft hole 10 formed in the protrusion attached tubular bulging portion 4a is finished in the shaft hole finishing process 80.
As illustrated in
The second punch 81 illustrated in
In addition, as illustrated in
Note that since the blank 2a is upset and is inserted into the first die 72 and the second die 82, the first die 72 and the second die 82 in
Note that the protrusion portion 3 is formed so as to occupy ⅓ the height of the blank 2a from the top. However, since the blank 2a is upset and is inserted into the second die 82, a depression 82b that allows the outer circumferential surface of the other ⅔ of the blank 2a that does not have the protrusion portion 3 of the material 2a to be inserted thereinto needs to be formed in the second die 82. Thus, the depression 82b is formed throughout the second die 82 in the up and down direction.
Thereafter, in the shaft hole finishing process 80, as illustrated in
In addition, in the shaft hole finishing process 80, the largest diameter of the second punch 81 is larger than that of the first punch 71 used in the shaft hole forming process 70 by 0.2 mm. However, the blank 2a cannot bulge outward due to the presence of the stripper 83e and the die folder 74a in the up and down direction and the second die 82 in the outer circumferential direction. Accordingly, although in the shaft hole finishing process 80, the shaft hole 10 is increased by only 0.2 mm, the excess thickness is not made into a punched slug. Instead, as illustrated in
Thereafter, by using the second punch 81, the second die 82, and a 500-ton transfer press machine, the shaft hole 10 that has a diameter of about 8.8 mm and that is formed in the protrusion attached tubular bulging portion 4a is finished into the shaft hole 10 that has a diameter of 9.0 mm.
The shaft hole finishing process is described with reference to
Thereafter, the blank 2a is upset and is inserted into the second die 82. The upper die set 73 is lowered. The stripper 83e of the upper die set 73 is brought into contact with the second die 82 so that the protrusion 83g of the stripper 83e mates with the depression 82b of the second die 82. Subsequently, the blank 2a other than a portion of the shaft hole 10 formed in the blank 2a is fixed between the stripper 83e and the die folder 74a in the up and down direction by the spring 73f. Thereafter, the second punch 81 is lowered. Thus, the shaft hole 10 is finished.
Subsequently, the upper die set 73 is raised to the original position, and the blank 2a having the finished shaft hole 10 formed therein is pushed upward out of the second die 82 by a hydraulic power unit (not illustrated). In this way, the shaft hole finishing process 80 is completed.
As illustrated in
As illustrated in
The blank 2a is fixed to the bending die 92, and the bending punch 91 is lowered. Thus, the blank 2a is bent into an L shape so that the thick-wall portion 7 of the blank 2a is located on the inward side. In this manner, the bending process 90 is completed.
As illustrated in
Note that a hole punch 101 used in the hole forming process 100 has two cylindrical portions 101a each having an external diameter of 14 mm. A hole die 102 has two hole portions 102a each having a diameter of 14 mm.
When the hole forming process 100 is completed, the method for manufacturing the chassis-side door hinge 1a according to the first embodiment is completed.
While the above-described manufacturing method according to the first embodiment includes the planarization cutting process 20, the cold heading process 30, the wall thickness increasing process 40, the thin-wall forming process 50, the shape reforming process 60, the annealing process 65, the shaft hole forming process 70, the shaft hole finishing process 80, the bending process 90, and the hole forming process 100, the present invention is characterized by the cold heading process, the shaft hole forming process, and the shaft hole finishing process. Accordingly, the planarization cutting process, the wall thickness increasing process, the thin-wall forming process, the shape reforming process, the annealing process, the bending process, and the hole forming process may be removed or may be performed in another process.
A method for manufacturing a motor vehicle door hinge according to a second embodiment of the present invention is described next with reference to
The method for manufacturing a motor vehicle door hinge according to the first embodiment is related to a chassis-side door hinge. In contrast, the method for manufacturing a motor vehicle door hinge according to the second embodiment is related to a door-side door hinge to be attached to a door.
The structure of a door-side door hinge according to the second embodiment differs from that of the chassis-side door hinge according to the first embodiment in that while the chassis-side door hinge includes the protrusion serving as a door stopper, the door-side door hinge has a contact portion that is brought into contact with the protrusion. In addition, the door-side door hinge is smaller than the chassis-side door hinge due to restriction imposed on a mounting area.
The same numbering will be used in referring to a manufacturing process as is utilized above in describing the first embodiment and, therefore, description of a similar manufacturing process is not repeated or is briefly made.
As illustrated in
A motor vehicle door hinge 1b in
The above-described processes 20 to 100 for the motor vehicle door hinge 1b are sequentially described next with reference to
In a planarization process 20a illustrated in
Subsequently, as illustrated in
As illustrated in a plan view of
The double header machine 31 includes a cold heading die 32b illustrated in
In a first process 30b of the cold heading process 30 performed by the double header machine 31, as illustrated in
Subsequently, in a second process 30c of the cold heading process 30 performed by the double header machine 31, as illustrated in
Thereafter, in a third process 30d of the cold heading process 30, as illustrated in
The cold heading punch 34b applies a pressing force to the cutting surface of the blank 2b such that the cold heading punch 34b is not brought into contact with the cold heading die 32b and performs the cold heading process. As illustrated in
Note that since the blank 2b bulges in the circumferential direction of the cylindrical bulging portion 4b, a burr is negligibly formed in the circumferential direction.
Subsequently, the wall thickness increasing process 40, the shape reforming process 60, the shaft hole forming process 70, the shaft hole finishing process 80, the bending process 90, and the hole forming process 100 are performed using a 500-ton transfer press machine.
As illustrated in
In the wall thickness increasing process 40, a thick-wall portion 7b is formed in the middle of the blank 2b. Subsequently, in the bending process 90 (described in more detail below), the thick-wall portion 7b is bent into an L shape.
Thereafter, in the shape reforming process 60 illustrated in
The annealing process 65 is the same as that of the first embodiment and, therefore, description of the annealing process 65 is not repeated.
The shaft hole forming process 70 is described next with reference to
The first punch 71 is similar to that of the first embodiment and, therefore, description of the first punch 71 is not repeated. In addition, as illustrated in
In addition, the first die 172 has a positioning portion 172c formed therein. The top end of the cylindrical bulging portion 4b of the blank 2b is brought into contact with the positioning portion 172c. Thus, the outer circumferential surface of the blank 2b is inserted into an inner wall 172d so that any gap is not formed therebetween except for a portion that the cylindrical bulging portion 4b faces.
In addition, a portion of the first die 172 in which one of the cut-out portions 6c in the other end corner of the blank 2b (the upper cut-out portion 6c) is located functions as an empty portion 172e (refer to
Note that
The shaft hole 10 is formed in the shaft center of the cylindrical bulging portion 4b using the first punch 71, the first die 172, and the 500-ton transfer press machine.
As illustrated in
The stripper 173e has a hollow cylindrical portion 173f that mates with the upper 6-mm part of the cylindrical bulging portion 4b and a protruding portion 173g that mates with the empty portion 172e of the first die 172. The die folder 174a has a hollow cylindrical portion 174e that mates with the lower 6-mm part of the cylindrical bulging portion 4b.
The blank 2b is inserted into the first die 172. The upper die set 73 is lowered so that the stripper 173e of the upper die set 73 is brought into contact with the first die 172. Thereafter, the upper and lower surfaces of a portion of the blank 2b other than a portion of the shaft hole 10 formed in the blank 2b is fixed between the stripper 173e and the die folder 174a by the spring 73f. Subsequently, the first punch 71 is lowered. Thus, the shaft hole 10 is formed. At that time, a hole portion formed from the end at which machining of the first punch 71 starts to ⅘ the length of the shaft hole 10 does not produce a punched slug, and the cylindrical bulging portion 4b bulges outward and, thus, the gap volume 172b of the first die 172 is fully filled with the bulging portion. Thereafter, a hole portion formed from ⅘ the length of the shaft hole 10 to the end at which the machining of the first punch 71 ends produces a punched slug, and the punched slug is ejected to the outside through a slug ejection port 74d.
Subsequently, the upper die set 73 is raised to the original position, and the blank 2b having the shaft hole 10 formed therein is pushed upward out of the first die 172 by a hydraulic power unit (not illustrated). In this way, the shaft hole forming process 70 is completed.
As described above, the blank 2b subjected to the shaft hole forming process 70 has a tubular bulging portion 4c transformed from the cylindrical bulging portion 4b prior to the shaft hole forming process 70.
The blank 2b subjected to the shaft hole forming process 70 is upset by the transfer press machine, and the shaft hole 10 formed in the tubular bulging portion 4c is finished in the shaft hole finishing process 80.
Like the first embodiment, in the shaft hole finishing process 80, the shaft hole 10 formed in the tubular bulging portion 4c of the blank 2b through the shaft hole forming process 70 is accurately finished using a second punch and a second die (not illustrated).
The second punch is similar to the second punch 81 according to the first embodiment and, therefore, illustration and description of the second punch are not repeated.
In addition, since the blank 2b is upset from the position in the first die 172 and is inserted into the second die, the blank 2b is disposed symmetrically in the up and down direction with respect to the first die 172 illustrated in
As in the first embodiment, in the shaft hole finishing process 80, the transfer press machine that is used in the shaft hole forming process 70 is also used. The second punch is attached to the upper die set 73, and the second die is fixed to the lower die set 74. As in the shaft hole forming process 70, the upper die set 73 of the transfer press machine is moved up and down. Thus, as in the first embodiment, the shaft hole 10 is finished (not illustrated).
In addition, in the shaft hole finishing process 80, the largest diameter of the second punch 81 is larger than that of the first punch 71 used in the shaft hole forming process 70 by 0.2 mm, as in the first embodiment. However, the blank 2b cannot bulge outward due to the presence of the stripper 173e and the die folder 172 in the up and down direction and the second die 172 in the outer circumferential direction. Accordingly, although in the shaft hole finishing process 80, the shaft hole 10 is increased by only 0.2 mm, the excess thickness does not produce a punched slug. Instead, as illustrated in
Thereafter, as illustrated in
As in the first embodiment, in the bending process 90 illustrated in
Thereafter, the blank 2b is fixed to the bending die 92, and the bending punch 91 is lowered. Thus, the blank 2b is bent into an L shape so that the thick-wall portion 7b of the blank 2b is located on the inward side. In this manner, the bending process 90 is completed.
As illustrated in
Note that a hole punch 101b used in the hole forming process 100 has a cylindrical portion 101c with an external diameter of 14 mm, and a hole die 102b has a hole portion 102c with a diameter of 14 mm.
When the hole forming process 100 is completed, the method for manufacturing the motor vehicle door hinge 1b according to the second embodiment illustrated in
While the above-described manufacturing method according to the second embodiment includes the planarization cutting process 20, the cold heading process 30, the wall thickness increasing process 40, the shape reforming process 60, the annealing process 65, the shaft hole forming process 70, the shaft hole finishing process 80, the bending process 90, and the hole forming process 100, the present invention is characterized by the cold heading process, the shaft hole forming process, and the shaft hole finishing process. Thus, the planarization cutting process, the wall thickness increasing process, the shape reforming process, the annealing process, the bending process, and the hole forming process may be removed or may be performed in another process.
While the above first to second embodiments have been described with reference to the planarization cutting process 20 in which the steel coil stock 21 is cut into blanks each having a predetermined width by the cutting machine 22, the motor vehicle door hinge may be manufactured from a blank having a predetermined size in advance. In such a case, the need for the planarization cutting process 20 and the first process of the cold heading process 30 can be eliminated.
A method for manufacturing a motor vehicle door hinge according to a third embodiment of the present invention is described next with reference to
Like the first embodiment, the method for manufacturing a motor vehicle door hinge according to the third embodiment is related to a chassis-side door hinge.
In the first embodiment, the method for manufacturing a motor vehicle door hinge from a single blank 2a. However, according to the third embodiment, the first member 2e and the second member 2f are manufactured from a first blank 2c and a second blank 2d, respectively. Thereafter, the manufactured first member 2e and second member 2f are integrated into one body. In this manner, the chassis-side motor vehicle door hinge 1c is manufactured.
A method for manufacturing the first member 2e from the first blank 2c, a method for manufacturing the second member 2f from the second blank 2d, and a method for integrating the first member 2e with the second member 2f to manufacture the chassis-side motor vehicle door hinge 1c according to the third embodiment are described below.
The method for manufacturing the first member 2e according to the third embodiment includes some of the manufacturing processes that are the same as those of the method for manufacturing the chassis-side door hinge 1a according to the first embodiment. The same numbering will be used in referring to a manufacturing process as is utilized above in describing the first embodiment and, therefore, description of the manufacturing process is not repeated or is briefly made.
As illustrated in
In the planarization cutting process 20, an SS400 steel coil stock 21 having a thickness of 9 mm and a height of 25 mm, which extends in the up and down direction when the first member 2e is used as a door hinge, is planarized by a feed roll (not illustrated). Thereafter, the steel coil stock 21 is cut into pieces each having a width of 55 mm by a cutting machine 22. In this way, the first steel blank 2c having a thickness of 9 mm, a width of 55 mm, and height of 25 mm is formed (refer to
Since the cold heading process 30 is the same as that of the first embodiment and, therefore, description of the cold heading process 30 is not repeated.
Thereafter, the subsequent shape reforming process 60, shaft hole forming process 70, and shaft hole finishing process 80 are performed using a 500-ton transfer press machine.
In the shape reforming process 60 illustrated in
The first blank 2c that is processed before this point in time has been subjected to the annealing process 65, the shaft hole forming process 70, and the shaft hole finishing process 80. Since the processes 65, 70, and 80 are the same as those of the first embodiment, descriptions of the processes 65, 70, and 80 are not repeated.
Note that the width of the first blank 2c and the presence of the stepped portion 6d on the other side according to the third embodiment differ from those of the blank 2a according to the first embodiment. Accordingly, the upper die set and the lower die set that are suitable for the first blank 2c are used in the shaft hole forming process 70 and the shaft hole finishing process 80.
While the above-described method for manufacturing the first member 2e according to the third embodiment includes the planarization cutting process 20, the cold heading process 30, the shape reforming process 60, the annealing process 65, the shaft hole forming process 70, and the shaft hole finishing process 80, the present invention is characterized by the cold heading process, the shaft hole forming process, and the shaft hole finishing process. Thus, the planarization cutting process, the shape reforming process, and the annealing process may be removed or may be performed in another process.
A method for manufacturing the second member 2f according to the third embodiment is described next with reference to
As illustrated in
The second member 2f is a plate-like member having a polygonal shape, that is, a shape of a substantially right triangle when viewed from the front as the second member 2f is in use. The size of the second member 2f in the height direction is larger than the height of the first member 2e (the first blank 2c). One of the sides that form the right angle extends horizontally, and the other side extends vertically. The second member 2f has a quadrilateral hole 13 that mates with the stepped portion 6d of the first member 2e and mounting holes 14e and 14f used when the second member 2f is mounted on the vehicle body.
As illustrated in
A die and the processed shapes according to a method for manufacturing the second member 2f from the second blank 2d formed by planarizing the coil stock through the transfer press molding process 110 are described.
Dice separated into an upper die and a lower die are mounted on the 500-ton transfer press machine. An SS400 steel second blank 2d having a thickness of 9 mm and a height of 120 mm is placed between the upper die and the lower die and is pressed by the upper die and the lower die. In this way, the second blanks 2d are sequentially pressed into a shape. First process 111 to seventh process 117 described below are disposed on a single die surface at an even pitch. Each time a press operation or a punch operation of the press machine is performed, the second blank 2d is fed to the subsequent process by a feeding apparatus 118. Thus, a forming process is performed.
As indicated by a dashed line 14a illustrated in
In the second process 112, a portion indicated as a slant line portion 14c is reformed by the die so that the thickness of the slant line portion 14c on the back of the plane of the drawing is decreased. Thus, the thickness is decreased from 9 mm to 6 mm.
In the third process 113, a portion 14d expanded over the outer circumferential surface in the second process 112 is cut off by the punch, and the mounting holes 14e and 14f used for mounting the second member 2f on the vehicle body are formed in the acute angle portions of the substantially right triangle portion.
In the fourth process 114, in order to form the quadrilateral hole 13, a quadrilateral hole 13a having a height and a width that are smaller than those of the stepped portion 6d of the first member 2e by 1 mm (i.e., a height of 20 mm and a width of 4 mm) is punched out.
In the fifth process 115, the quadrilateral hole 13a formed in the fourth process 114 is subjected to chamfering by pressing a punch in the shape of truncated pyramid into the quadrilateral hole 13a so that a taper surface 13b (refer to
In the sixth process 116, in order to form the quadrilateral hole 13 that mates with the stepped portion 6d of the first member 2e, the quadrilateral hole 13c having the taper surface 13b formed through the fifth process 115 is punched using a punch having a height and a width that are larger than those of the punch used in the fourth process 114 by 1 mm (i.e., the quadrilateral hole 13 with a height of 21 mm and a width of 5 mm). In addition, the excess thickness generated in the fifth process 115 is made into a punched slug.
In the seventh process 117, the partially connected portion of the second member 2f is punched off. Thus, manufacturing of the second member 2f illustrated in
In addition, as indicated by the partial enlarged cross-sectional view of
A method for integrating the first member 2e with the second member 2f and manufacturing the chassis-side motor vehicle door hinge 1c through an integration process 120 according to the third embodiment is described next.
As illustrated in
In this way, the end part of the stepped portion 6d of the first member 2e protrudes outwardly from the attaching surface 13d on the side of the taper surface 13b of the quadrilateral hole 13 by 1.5 mm as a protrusion portion 15.
The protrusion portion 15 of the first member 2e is subjected to a caulking process using a punch 122. Thus, the protrusion portion 15 is crushed into a space formed between the taper surface 13b of the quadrilateral hole 13 and the stepped portion 6d so that a caulked portion is flush with the attaching surface 13d.
Through such an integration process 120, the first member 2e is firmly integrated with the second member 2f. Thus, the chassis-side motor vehicle door hinge 1c is manufactured.
While the above third embodiment has been described with reference to the second member 2f produced through the transfer press molding process 110, the second member 2f can be press-formed using an individual die. In addition, the second member 2f is formed so as to have a shape of a right triangle when viewed from the front during use. However, the shape may be a rectangular shape.
In addition, while the above third embodiment has been described with reference to a process in which the taper surface 13b is provided in the quadrilateral hole 13 of the second member 2f and, thereafter, the first member 2e is integrated with the second member 2f using a caulking process, the first member 2e can be integrated with the second member 2f by a caulking process without providing the taper surface 13b.
Furthermore, while the above third embodiment has been described with reference to the taper surface 13b provided in the quadrilateral hole 13 of the second member 2f as illustrated in
In such a case, the taper surface 13e can be formed using, instead of the fourth process 114, the fifth process 115, and the sixth process 116, a taper surface forming process 130 illustrated in
In addition, a quadrilateral hole 132a having a size of 23 mm×7 mm is formed in a die 132. By forming the taper surface 13e of the quadrilateral hole 13 in this manner, the manufacturing processes and production of the dice can be simplified.
While the above first and third embodiments have been described with reference to a method for manufacturing a chassis-side door hinge having the vehicle door stopper protrusion portion 3, the need for the door stopper protrusion portion 3 can be eliminated.
While the above first to third embodiments have been described with reference to the cold heading process 30 using the double header machine 31, a parts former machine or a bolt former machine can be used instead of a double header machine.
While the above first to third embodiments have been described with reference to the annealing process on the basis of a transformation temperature, soft annealing in which a temperature that is lower than or equal to the transformation temperature is maintained may be employed.
In the above-described first to third embodiments, each of the first punch 71 and the second punch 81 has a top end having a cone angle of 90°. It is desirable that the cone angle be in the range from 70° to 120°.
In particular, if the cone angle of the first punch 71 is smaller than 70°, the excess thickness of the shaft hole moves in the circumferential direction of the punch and, therefore, the stress of the punch is increased. Thus, the blank is easily damaged. Accordingly, that cone angle is not desirable.
In addition, if the cone angle of the first punch 71 is larger than 120°, a large pushing force is exerted on the front of the shaft hole and, therefore, a portion in the vicinity of the shaft hole is pulled in the penetrating direction, therefore, the stress of the punch is also increased. Thus, the blank is easily damaged. In addition, the shear droop formed at the end of the shaft hole at which machining of the punch starts is increased. Thus, the shear droop prevents a practical use. Accordingly, that cone angle is not desirable.
Note that the shape of the second punch 81 may be a truncated cone instead of a cone.
In addition, in the above-described first to third embodiments, for the first die 72 and the first die 172, the gap volume 72b is formed between the outer circumferential surface of the cylindrical bulging portion 4 and the inner wall 72a of the first die 72, and the gap volumes 172b is formed between the outer circumferential surface of the cylindrical bulging portion 4b and the inner wall 172a of the first die 172. At that time, the sizes of the gap volumes 72b and 172b are set so that when the first punch 71 punches the cylindrical bulging portions 4 and 4b of the blanks 2a, 2b, and 2c, a hole portion formed from the end at which machining of the first punch 71 starts to ⅘ the length of the cylindrical bulging portion 4 or 4b bulges outward without producing a punched slug and, in addition, a hole portion formed from ⅘ the length to the end at which the machining of the first punch 71 ends produces a punched slug which is ejected. However, the value set to ⅘ the length may be changed to a value in the range from ¾ to ⅚ the length.
If the value is set to a value less than ¾ the length, each of the cylindrical bulging portions 4 and 4b does not bulge outward into the lower portion of the gap volume. If the value is set to a value greater than ⅚ the length, the stress that acts on the first punch is excessively increased.
Furthermore, while the above first to third embodiments have been described with reference to the cylindrical bulging portions 4 and 4b having a horizontal cross section of an elliptic shape and formed through the cold heading process 30, a protrusion attached cylindrical bulging portion 4d or a cylindrical bulging portion 4e having a horizontal cross section of a circular shape illustrated in
Note that
Still furthermore, while the above first to third embodiments have been described with reference to the annealing process 65 performed after the shape reforming process 60 is completed and before the shaft hole forming process 70 is started in order to remove work hardening generated in the processes prior to the shaft hole forming process 70 as illustrated in
By performing the annealing process immediately after the cold heading process 30 is performed in this manner, all of the processes subsequent to the cold heading process 30 can be continuously performed using a transfer press machine. For example, in the first embodiment, the wall thickness increasing process 40, the thin-wall forming process 50, the shape reforming process 60, the shaft hole forming process 70, the shaft hole finishing process 80, the bending process 90, and the hole forming process 100 can be advantageously performed by one operation of the transfer press machine at the same time while feeding the blank 2a, 2b, or 2c to the next process each time the transfer press machine operates.
Yet still furthermore, while the above first to third embodiments have been described with reference to the shaft hole forming process 70 and the shaft hole finishing process 80 performed by cold working after the annealing process 65 is performed, the shaft hole forming process and the shaft hole finishing process can be performed by warm working.
If the shaft hole forming process and the shaft hole finishing process can be performed by warm working, the temperature of the protrusion attached cylindrical bulging portion is set to a temperature in the range from 450° to 900°. The protrusion attached cylindrical bulging portion is heated by a high-frequency heating apparatus attached to the transfer press machine.
It is desirable that the temperature of the protrusion attached cylindrical bulging portion be set to a temperature in the range from 600° to 800° and is more desirable that the temperature be set to a temperature in the range from 650° to 750°.
In such a case, the sizes of the first punch, the first die, the second punch, and the second die are determined while taking into account the thermal expansion of the blank occurring during warm working and the thermal expansion of the product occurring during use at a room temperature.
That is, since the punches and dice are made of a material having a low coefficient of thermal expansion, the sizes of the first punch, the first die, the second punch, and the second die are produced so as to be larger than the design values thereof for a room temperature while taking into account the differences of the coefficient of thermal expansion.
If cold working is employed, the stress that acts on the first punch and the first die in the shaft hole forming step is increased and, thus, the volume of the press machine is increased. However, the working accuracy is advantageously increased. In contrast, if warm working is employed, the need for the annealing process is eliminated and, thus, the volume of the press machine can be decreased. However, a high-frequency heating apparatus is disadvantageously required. In addition, the working accuracy is disadvantageously lower than that in cold working.
A method for manufacturing a motor vehicle door hinge according to a fourth embodiment of the present invention is described next with reference to
According to the fourth embodiment, a motor vehicle door hinge pair 1d and a motor vehicle door hinge pair 1e are manufactured using the door-side motor vehicle door hinge 1b produced by the method for manufacturing a motor vehicle door hinge according to the second embodiment and one of the chassis-side door hinge 1a produced by the method for manufacturing a motor vehicle door hinge according to the first embodiment and the chassis-side motor vehicle door hinge 1c produced by the method for manufacturing a motor vehicle door hinge according to the third embodiment.
a) and 41(b) illustrate the motor vehicle door hinge pair 1d produced from the chassis-side door hinge 1a manufactured in the first embodiment and to be attached to a vehicle body and the door-side door hinge 1b manufactured in the second embodiment. A tubular plastic shock-absorbing member (not illustrated) is inserted into each of the above-described shaft holes of the door hinges 1a and 1b. A head hinge pin 16 is inserted into the two plastic shock-absorbing members and a washer 17 so as to pass through the two plastic shock-absorbing members and the washer 17. Thereafter, the end portion 16a of the head hinge pin 16 is subjected to a caulking process. In this manner, the motor vehicle door hinge pair 1d is produced.
In addition,
While the above first to fourth embodiments have been described with reference to a method for manufacturing a motor vehicle door hinge suitable for large cars and high-class cars having a heavy-weight door, it is appreciated that the first to fourth embodiments are applicable to small cars and standard-sized cars having a light-weight door. For small cars and standard-sized cars, the exemplary sizes shown in the above-described embodiments are reduced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-067801 | Mar 2010 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2011/055321 | Mar 2011 | US |
| Child | 13618729 | US |
