JP2006326624A - Production method of square pipe using press apparatus and press apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a square pipe exhibiting a deformed section, such as a rectangular shape in section by using a press apparatus having versatility without restrictions on the size of a steel pipe with high quality at a low cost with a smaller man-hour for working. <P>SOLUTION: In a first process, an upper die 11 and a lower die 12 of a V shape in section recessed with respect to a round steel pipe 30 are installed to the press apparatus. The upper die 11 is moved downward toward the lower die 12 side and in synchronization with the downward movement, a side die 14 moves downward at a descending speed slower than the descending speed of the upper die. As a result, the sectional round shape of the steel pipe 30 is formed to a shape having a long side of a V-shape corresponding to the shape of the sectional shape of the upper die 11 and the lower die 12 and having a square R section, finally. In a second process, the vertex portion of the sectional V shape of the square steel pipe 30 is restruck by the upper die and lower die for forming the flat long side, thereby forming the flat long side and producing the square steel pipe 30 of the rectangular shape in section. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a square tube using a press device and a press device for manufacturing a square tube by pressing.

  When manufacturing a frame structure such as a vehicle, a square steel pipe (hollow pipe) having a square cross-sectional shape may be used. For example, when the cab of a hydraulic excavator is configured with a frame structure, square steel pipes with a rectangular cross section are used for the pillars that configure the frame structure in order to ensure strength without damaging the internal space of the cab. The

  As a method for manufacturing a square steel pipe, a roll forming method has been widely known. For example, Patent Document 1 described later describes a method of manufacturing a square steel pipe by a roll forming method.

  In the roll forming method, commercially available round steel pipes are sequentially pushed into the multi-stage roll stands constituting the roll forming machine, and the cross section of the steel pipe is gradually deformed from a round shape to a square shape each time it passes through each roll stand. This is a method of forming a square steel pipe. In addition, a round steel pipe is manufactured by winding a steel plate and welding end surfaces.

  On the other hand, a method of forming a round steel pipe into a square steel pipe using a press device is disclosed in Patent Document 2 described later.

In Patent Document 2, as shown in FIG. 13, a process of pressing a round steel pipe and deforming a cross section of the round steel pipe by a rectangular upper and lower die having an isosceles base angle, and rotating the round steel pipe 90 ° around the axis The invention of forming into a square steel pipe having a square cross-section by repeating the step of forming is described.
JP-A-6-172856 JP-A-3-285713

  However, in the roll forming method described in Patent Document 1, there is a restriction on the size of the square steel pipe that can be formed. The above-described square steel pipe for a driver's cab pillar is large in size, and the roll forming method makes it difficult to form and increases the number of processing steps.

  In addition, the roll forming machine is a processing machine dedicated to square steel pipes, and has no application other than manufacturing square steel pipes and lacks versatility. In addition, there is an aspect that the capital investment is costly.

  Also, the roll forming method has a quality problem that the circumference of the tube contracts during the molding process.

  On the other hand, since the molding method described in Patent Document 2 uses a press device, it is rich in versatility and has the advantage that it does not cost equipment investment (existing equipment can be used).

  However, in the forming method described in Patent Document 2, a square steel pipe having a square cross section such as a rectangular cross section, such as the square steel pipe for a driver's cab pillar described above, can be manufactured even if a square steel pipe having a square cross section can be manufactured. Can not be manufactured.

  The present invention has been made in view of such a situation, and without any restriction on the size of the steel pipe, a square steel pipe exhibiting a deformed cross section such as a rectangular cross section can be obtained with high quality using a versatile press device, and Therefore, it is an object of the present invention to make it possible to manufacture at a low cost and with a small number of processing steps.

The first invention is
A method of manufacturing a square tube, in which a round tube is set between an upper die and a lower die of a press device, and the round tube is formed into a square tube,
The upper mold and the lower mold having a V-shaped cross section recessed with respect to the pipe are installed in the press device,
While moving one of the upper mold and the lower mold toward the other mold side, the side mold is moved to the other mold so that the contact point where the side mold contacts the pipe moves in synchronization with this movement. Move it at a speed slower than the mold speed,
The cross section of the tube is formed into a shape having a corner R portion.

The second invention is
A method of manufacturing a square tube, in which a round tube is set between an upper die and a lower die of a press device, and the round tube is formed into a square tube,
In the first step,
The upper mold and the lower mold having a V-shaped cross section recessed with respect to the pipe are installed in the press device,
While moving one of the upper mold and the lower mold toward the other mold side, the side mold is moved to the other mold so that the contact point where the side mold contacts the pipe moves in synchronization with this movement. Move it at a speed slower than the mold speed,
The cross section of the tube is shaped into a shape having a V-shaped long side corresponding to the cross-sectional shape of the upper die and the lower die, and having a corner R portion,
In the second step,
Lisk-like the top of the V-shaped section of the tube, and install the upper and lower molds to form a flat long side in the press device,
Move one of the upper and lower molds toward the other mold,
The cross section of the tube is formed into a rectangular shape.

The third invention is the second invention,
In the second step, the upper mold and the lower mold installed in the press machine are
It has a cross-sectional shape in which a portion facing the corner R portion of the tube is recessed.

A fourth invention is the second invention,
In the second step, one of the upper mold and the lower mold is moved toward the other mold side, and in synchronization with this movement, the contact point where the side mold contacts the pipe moves. The side mold is moved at a speed slower than the speed of the one mold.

5th invention is 1st invention-4th invention,
Synchronize the side mold with one of the upper and lower molds facing the other mold so that the contact point where the side mold contacts the pipe is maintained at the midpoint between the upper and lower molds. It is characterized by moving.

A sixth invention is the first invention to the fifth invention,
It is characterized in that the side mold is moved at a speed that is 1/2 of the speed at which either the upper mold or the lower mold moves.

The seventh invention
A pressing device that performs a pressing process for setting a round tube between an upper die and a lower die and forming the round tube into a square tube,
An upper die and a lower die having a concave V-shaped cross section with respect to the tube;
Side molds arranged on the sides of these upper mold and lower mold,
In synchronization with the movement of one of the upper mold and the lower mold toward the other mold side, the side mold is moved faster than the speed of the one mold so that the contact point where the side mold contacts the pipe moves. And a synchronization mechanism that moves at a slow speed.

In an eighth aspect based on the seventh aspect,
A press device for forming a round tube into a square tube through a first step and a second step subsequent thereto,
In the first step,
An upper die and a lower die having a concave V-shaped cross section are installed in the press device with respect to the pipe,
The cross section of the tube has a V-shaped long side corresponding to the cross-sectional shapes of the upper mold and the lower mold, and is molded into a shape having a corner R portion,
In the second step,
An upper die and a lower die for forming a flat long side by re-slicing the apex of the V-shaped section of the tube formed by the first step are installed in the press device,
The cross section of the tube is formed into a rectangular shape.

A ninth invention is the eighth invention,
In the second step, the upper mold and the lower mold installed in the press machine are
It has a cross-sectional shape in which a portion facing the corner R portion of the tube is recessed.

The tenth invention is the seventh invention to the ninth invention,
The synchronization mechanism is
Synchronize the side mold with one of the upper and lower molds facing the other mold so that the contact point where the side mold contacts the pipe is maintained at the midpoint between the upper and lower molds. It is a mechanism that moves it.

The eleventh invention is the seventh invention to the tenth invention,
The synchronization mechanism is
It is a mechanism that moves the side mold at a speed that is 1/2 of the speed at which either the upper mold or the lower mold moves.

In the second invention and the eighth invention, the first step and the second step are performed using the press device 10.
That is, in the first step, as shown in FIG. 1 and FIGS. 2 (a) and 2 (b), the upper die 11 and the lower die 12 having a concave V-shaped cross section with respect to the round steel pipe 30 are pressed. 10 is installed.

  Then, the upper mold 10 is moved downward toward the lower mold 11, and the side molds 13 and 14 are moved downward at a lower movement speed slower than the lower movement speed of the upper mold 10 in synchronization with the lower movement. .

  As a result, as shown in FIGS. 4A, 4B, and 4C, the round sectional shape of the steel pipe 30 (FIG. 4A) is finally changed to the sectional shapes of the upper die 11 and the lower die 12. It has a corresponding V-shaped long side and is formed into a shape having a corner R (FIG. 4C). The long side of the square steel pipe 30 'does not buckle or swell greatly, and the shape of the square steel pipe 30' is uniform at the top and bottom, and the same corner R portion is formed above and below the square steel pipe 30 '. (FIG. 4C).

  In the second step, as shown in FIGS. 3A and 3B, the apex portion of the V-shaped section of the square steel pipe 30 'formed in the first step is reshaped and formed into a flat long side. The upper mold 11 and the lower mold 12 are installed on the press device 10.

  Then, the upper mold 10 is moved downward toward the lower mold 11 side.

  As a result, the vertex of the V-shaped cross section of the square steel pipe 30 'is re-sliced and formed into a flat long side to produce a square steel pipe 30 "having a rectangular cross section.

  If the present invention is contrasted with the prior art, a square steel pipe 30 ″ having an irregular cross section such as a rectangular cross section without restriction on the size of the steel pipe 30 can be obtained with a high quality by using a versatile press device 10 and The effect that it can manufacture at low cost and with a small processing man-hour is acquired.

  In the third and ninth inventions, as shown in FIGS. 3 (a), 3 (b) and 11 (a), as the upper mold 11 and the lower mold 12 used in the second process, What has the cross-sectional shape in which the site | part facing a corner | angular R part is dented is used.

  In the fourth invention, in the second step, as in the first step, the upper mold 11 is moved downward toward the lower mold 12 side, and the side molds 13, 14 are moved in synchronization with the lowering movement. The mold 11 moves downward at a speed slower than the downward movement speed of the mold 11.

  As a result, in the second step, the upper and lower corners R of the square steel pipe 30 ″ are uniformly formed, and the square steel pipe 30 ″ is formed in a uniform shape.

  In the fifth and tenth inventions, as shown in FIGS. 9A, 9B, and 9C, the side contact point P3 moves to the lower side in accordance with the lowering movement of the upper mold 11, and contacts The point P3 always moves so as to be maintained at the intermediate point between the upper die 11 and the lower die 12, that is, the center point in the vertical direction of the steel pipe 30.

  In the sixth and eleventh inventions, the side molds 13 and 14 move downward at a speed that is 1/2 of the speed at which the upper mold 11 moves downward (including a range of approximately 1/2 speed).

  Therefore, according to the fifth, sixth, tenth, and eleventh inventions, as shown in FIGS. 9 (a), (b), and (c), as the deformation of the steel pipe 30 progresses, the upper contact occurs. Between the point P1 and the side contact point P3, and between the lower contact point P2 and the side contact point P are almost evenly narrowed. Between these contact points P1 and P3, the contact points P2 and P3. The upper and lower corners R are formed substantially evenly.

  For this reason, the shape of the square steel pipe 30 'is uniform in the vertical direction, and the upper and lower corner R portions of the square steel pipe 30' have the same shape.

  The first and seventh inventions are inventions excluding the second step in the second and eighth inventions.

  That is, even when the second step is omitted and the first step is performed, the square steel pipe 30 ′ having at least the corner R portion can be reliably manufactured. Depending on the specifications of the product of the square steel pipe, the square steel pipe 30 'after the first step may be sufficient. In addition, due to future technological advancement or the like, the swelling LD at the apex of the square steel pipe 30 '(see FIG. 10A) may fall within the allowable range only by the first step due to other solutions.

  In such a case, the first and seventh inventions in which the second step is omitted and only the first step is performed are applied.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing the configuration of the press apparatus 10 according to the embodiment.

  The press apparatus 10 according to the embodiment includes an upper mold (upper mold) 11 and a lower mold (lower mold) 12, and side molds 13 and 14 disposed on the left and right sides of the upper and lower molds 11 and 12. Yes. The side molds 13 and 14 are arranged on the side surfaces of the upper mold 11 and the lower mold 12 so as to be substantially in contact with each other.

  The upper mold 11 is attached to the lower part of the slide 15. The lower mold 12 is attached to the upper part of the bed 16.

  Power is transmitted to the slide 15 from a drive source such as a hydraulic cylinder or an electric motor (not shown) via a flywheel, a clutch mechanism, or the like as necessary, so that the slide 15 moves in the downward direction or the upward direction. As the slide 15 moves up or down, the upper mold 11 moves up or down.

  When the upper die 11 moves downward toward the lower die 12, the pressing device 10 moves the side dies 13, 14 in a downward movement speed slower than the downward movement speed of the upper die 11 in synchronization with the downward movement of the upper side 11. Is provided with a cam mechanism 20 as a synchronizing mechanism that moves downward.

  That is, the slide 15 is connected to the side molds 13 and 14 via the left and right cam mechanisms 20 in the drawing. The side molds 13 and 14 are formed with cam surfaces 23a, and the cam surfaces 23a have slip members 23b (hereinafter referred to as "slip members") that cause slip between the cam surfaces 23a and other cam surfaces. Used to mean a member that causes slippage between the two).

  The cam mechanism 20 includes a cam block 21, an intermediate cam block 22, a cam surface 23a of the side molds 13 and 14, and a sliding member 23b.

  The cam block 21 is connected to the slide 15 and has a cam surface 21a. The intermediate cam block 22 is interposed between the cam block 21 and the side molds 13 and 14, and is opposed to the cam surface 22 a facing the cam surface 21 a of the cam block 21 and the cam surface 23 a of the side molds 13 and 14. Cam surface 22c. A sliding member 22b is provided on the cam surface 22a.

  The inclination angles of the cam surface 21a (22a) and the cam surface 22c (23a) are 1/2 of the descending movement speed of the slide 15 (or approximately 1/2 speed), and the side molds 13 and 14 can move downward. It is set to such an angle.

  The side molds 13 and 14 are supported by springs 17.

  Between the upper mold | type 11 and the lower mold | type 12, the steel pipe 30 is set so that the direction perpendicular | vertical with respect to a paper surface may turn into the axial direction (longitudinal direction) of the steel pipe 30.

  When the slide 15 descends, the upper mold 11 moves downward toward the lower mold 12 side, and the cam mechanism 20 moves the upper mold 11, the steel pipe 30, and the lower mold 12 to the side mold in synchronism with this movement. 13 and 14 move. Thereby, the steel pipe 30 having a round cross section is formed into a steel pipe 30 'having a square cross section.

  FIG. 2A shows a state at the moment when the upper die 11 comes into contact with the steel pipe 30, and FIG. 2B shows a state where the press work is completed.

  The upper die 11 of the pressing device 10 in FIG. 1 descends from the upper side toward the lower die 12 in the order of FIGS. 1, 2A, and 2B.

  When the slide 15 moves downward, between the cam surface 21a of the cam block 21 and the sliding member 22b of the intermediate cam block 22, and between the cam surface 22c of the intermediate cam block 22 and the sliding member 23b of the side molds 13 and 14. Each slip occurs. In response to this, the cam block 21 moves downward in the direction indicated by the arrow A, the intermediate cam block 21 moves in the direction of the side molds 13 and 14 (inside) indicated by the arrow B, and the side molds 13 and 14 change to the arrow C. Move down in the direction shown.

  When the slide 15 is in the upper standby position, the side molds 13 and 14 are positioned at a predetermined position determined by the free length of the spring 17.

  When the slide 15 moves downward, the side molds 13 and 14 move downward against the spring force of the spring 17 via the cam mechanism 20.

  When the slide 15 moves upward, the side molds 13 and 14 are moved upward by the spring force of the spring 17 and positioned at a predetermined position determined by the free length of the spring 17.

(First embodiment)
Hereinafter, a method of forming a round steel pipe into a square steel pipe through the first step and the second step using the press device 10 described above will be described. In the following description, a steel pipe having a round cross section is referred to as a round steel pipe 30, a square steel pipe formed through the first process is referred to as 30 ', and a square steel pipe formed through the second process is referred to as 30 ". In this way, a dash “′” is given to the sign “30” to distinguish the cross-sectional shape of the steel pipe.

  FIG. 1 and FIGS. 2A and 2B show cross sections of the upper mold 11 and the lower mold 12 that are installed in the press apparatus 10 in the first step. FIG. 1 shows a state in which the upper mold 11 is in a standby position before the start of the first process, and FIG. 2A is a diagram showing a state in the first process, and the moment when the upper mold 11 contacts the steel pipe 30. FIG. 2B shows a state in which the first step is completed.

  The upper die 11 of the pressing device 10 in FIG. 1 is lowered from the upper side toward the lower die 12 in the order of FIGS. 1, 2A, and 2B in the first step. .

  3A and 3B show cross sections of the upper mold 11 and the lower mold 12 that are installed in the press apparatus 10 in the second step. FIG. 3A is a diagram showing a state in the second step, showing a state at the moment when the upper die 11 contacts the steel pipe 30, and FIG. 3B shows a state in which the second step is completed. .

  The upper die 11 of the pressing device 10 in FIG. 1 is directed from the standby position similar to FIG. 1 toward the lower die 12 from the top to the bottom in the order of FIGS. 3A and 3B in the second step. It shall descend.

  For the convenience of explanation, the operation of the right side of the symmetric line in the drawing of the press apparatus 10 (the upper die 11, the lower die 12 and the right die 14 of the right half) will be described, and the left side of the symmetric line in the drawing (left The operations of the half upper die 11, lower die 12, and left die 14) are omitted as appropriate because they are the same as those on the right side.

(First step)
In the first step, as shown in FIG. 1 and FIGS. 2A and 2B, the upper die 11 and the lower die 12 that are recessed with respect to the round steel pipe 30 are formed in the press device 10. Installed.

  Then, the upper mold 10 is moved downward toward the lower mold 11, and the side molds 13 and 14 are moved downward in synchronization with the downward movement.

  4 (a), 4 (b), and 4 (c) are diagrams showing, in chronological order, how the cross section of the steel pipe 30 is deformed.

  The cross-sectional shape of the steel pipe 30 (FIG. 4A) is deformed into a generally “egg” shape (FIG. 4B), and finally a V-shape corresponding to the cross-sectional shapes of the upper die 11 and the lower die 12 The long side of the square steel pipe 30 ′ is not buckled or bulged, and the shape of the square steel pipe 30 ′ is uniform in the vertical direction. Thus, corner R portions having the same shape were formed above and below the square steel pipe 30 '(FIG. 4C).

  Next, with reference to FIGS. 5, 6, and 7, the knowledge that the corner portion R can be formed without buckling or large swelling at the apex portion (long side center) of the steel pipe 30 in this embodiment. This will be described in comparison with a comparative example.

  5 and 6 show a comparative example with respect to this embodiment.

  FIG. 5 shows a comparative example 1 in which the steel pipe 30 is deformed by using the upper mold 11 and the lower mold 12 having a flat cross section with respect to the steel pipe 30 without providing the side molds 13 and 14. FIG. 5A is a cross-sectional view of the upper die 11 and the lower die 12, FIG. 5B is a perspective view of a formed steel pipe 30 ′, and FIG. 5C is a cross-sectional view of the formed steel pipe. .

  In the case of Comparative Example 1, buckling occurred at the apex of the steel pipe 30 ', and the desired square steel pipe 30' could not be formed.

  FIG. 6 shows that the side molds 13 and 14 are provided but are fixed at a fixed position, and the angle of the V-shaped section is smaller than that of the present embodiment, that is, the upper mold 11 and the lower mold having a V-shaped section smaller than the taper angle θ. 12 shows a comparative example 2 in which the steel pipe 30 is deformed. 6A is a cross-sectional view of the upper mold 11 and the lower mold 12, FIG. 6B is a perspective view of the formed steel pipe 30 ′, and FIG. 6C is a cross-sectional view of the formed steel pipe 30 ′. It is.

  In the case of Comparative Example 2, although the buckling at the apex of the steel pipe 30 'that occurred in Comparative Example 1 has disappeared, a large bulge occurred at the apex of the steel pipe 30' instead. Further, the corner R portion could not be formed.

  In FIG. 7, side molds 13 and 14 are provided and moved in synchronism with the upper mold 11, and the cross section V-shaped angle is larger than that of the comparative example 2, that is, the taper angle θ is larger. The present Example which changed the steel pipe 30 using the type | mold 11 and the lower mold | type 12 is shown. 7A is a cross-sectional view of the upper mold 11 and the lower mold 12, FIG. 7B is a perspective view of the formed steel pipe 30 ′, and FIG. 7C is a cross-sectional view of the formed steel pipe 30 ′. It is.

  In the case of this example, the buckling at the apex of the steel pipe 30 ′ that occurred in Comparative Example 1 disappeared, and the large swelling at the apex of the steel pipe 30 ′ that occurred in Comparative Example 2 disappeared. Further, the corner R portion could be formed satisfactorily.

  Next, using FIG. 8 and FIG. 9, in this embodiment, the shape of the square steel pipe 30 ′ is equal in the vertical direction, and the knowledge that the corner R portion can be formed in the same shape above and below the steel pipe 30 ′ is compared. This will be explained in comparison with an example.

  8A, 8B, and 8C show a comparative example with respect to the present embodiment. In the comparative example, unlike the present example, the side mold 14 (side mold 13) was fixed in place without being moved.

  8A, 8B and 8C show a contact point P1 where the upper mold 11 comes into contact with the steel pipe 30, a contact point P2 where the lower mold 12 comes into contact with the steel pipe 30, and the side mold 14 (side mold 13). The movement of the contact point P3 that contacts the steel pipe 30 is shown in time series.

  Contact points P1, P2, and P3 are points where a frictional force is generated between the steel pipe 30 and the mold.

  As shown in FIGS. 8A, 8 </ b> B, and 8 </ b> C, as the deformation of the steel pipe 30 progresses, the vertical contact points P <b> 1 and P <b> 2 change from the center side of the upper die 11 and the lower die 12 to the side die 14. Although it moves to the (side mold 13) side, the side contact point P3 is fixed at a fixed position.

  For this reason, as the deformation of the steel pipe 30 progresses, the space between the upper contact point P1 and the side contact point P3 narrows, and the deformation progresses between these points P1, P3, but the lower contact point P2 and the side contact point P3. The deformation between the contact point P1 and the contact point P3 does not proceed (the deformation does not shift downward).

  For this reason, the shape of the square steel pipe 30 'is not uniform in the vertical direction, and the upper and lower corner R portions of the square steel pipe 30' are different (the lower corner R portion has a very large radius), or The corner R portion is not formed below the steel pipe 30 '.

  When the side molds 13 and 14 are lowered at the same speed as the upper mold 13, conversely, the deformation proceeds on the lower side of the steel pipe 30 but does not proceed on the upper side, and similarly the shape of the square steel pipe 30 '. Becomes uneven at the top and bottom, and the upper and lower corners R of the square steel pipe 30 'have different shapes (the R of the upper corner R becomes a very large radius), or the corner R at the upper side of the square steel pipe 30'. Will not be formed.

  FIGS. 9A, 9B, and 9C are diagrams showing the movement of the contact points P1, P2, and P3 in the present embodiment, and are diagrams corresponding to FIGS. 8A, 8B, and 8C. It is.

  As shown in FIGS. 9A, 9B, and 9C, as the deformation of the steel pipe 30 progresses, the vertical contact points P1, P2 change from the center side of the upper die 11 and the lower die 12 to the side die 14 ( While moving to the side mold 13) side, the side contact point P3 moves downward.

  The side contact point P3 moves downward as the upper die 11 moves downward, and the contact point P3 is always an intermediate point between the upper die 11 and the lower die 12, that is, the center point in the vertical direction of the steel pipe 30. Move to be maintained.

  For this reason, as the deformation of the steel pipe 30 progresses, the space between the upper contact point P1 and the side contact point P3 and the space between the lower contact point P2 and the side contact point P are almost evenly narrowed. Between the point P3 and between the contact point P2 and the contact point P3, the upper and lower corners R are formed substantially evenly.

  For this reason, the shape of the square steel pipe 30 'is uniform in the vertical direction, and the upper and lower corner R portions of the square steel pipe 30' have the same shape.

(Second step)
FIG. 10A shows each size of the cross section of the square steel pipe 30 ′ obtained in the first step. LA is the length of the long side, and LB is the length of the short side. LC is the width of the vertex. The bulge (unevenness) LD at the apex is defined by LD = LC-LB.

  The bulge (unevenness amount) LD at the apex immediately after the first step is often outside the design tolerance range.

  In the second step, as shown in FIGS. 3A and 3B, the apex portion of the V-shaped section of the square steel pipe 30 'formed in the first step is reshaped and formed into a flat long side. The upper mold 11 and the lower mold 12 are installed on the press device 10. For example, an upper die 11 and a lower die 12 having a cross-sectional shape in which a portion facing the corner R portion of the square steel pipe 30 'is recessed and a portion facing the apex portion of the square steel pipe 30' is a flat surface is used. The Further, it is not always necessary to integrally mold the upper mold 11 and the lower mold 12, and as shown in FIG. 11 (a), the upper mold 11, the lower mold 12, and the steel pipe 30 'having a flat cross section with respect to the steel pipe 30'. Between the upper die 11 and the lower die 12, a plate material 18 having a lateral width smaller than that of the corner R portion of the square steel pipe 30 'may be interposed.

  Then, the upper mold 10 is moved downward toward the lower mold 11, and the side molds 13 and 14 are moved downward in synchronization with the downward movement.

  As a result, the apex portion of the V-shaped cross section of the square steel pipe 30 ′ is re-sliced and formed into a flat long side.

  FIG. 10B shows each size of the cross section of the square steel pipe 30 ″ obtained in the second step. The swelling (unevenness) LD at the apex of the square steel pipe 30 ″ after the third step is shown in FIG. Within the design tolerance range.

  In addition, the corner R portion of the square steel pipe 30 ′ is formed in a substantially desired shape (desired radius R) by the first step, but the corner R portion of the square steel pipe 30 ″ is surely formed by the second step. Fits within tolerances.

  As described above, the square steel pipe 30 ″ having a rectangular cross section is formed through the first step and the second step. In the second step, as in the first step, the upper die 11 is formed. The side molds 13 and 14 are moved downward in synchronization with the lowering movement of the steel plate, and the contact point P3 is always maintained at the intermediate point between the upper mold 11 and the lower mold 12, that is, the center point in the vertical direction of the steel pipe 30 '. As a result, the shape of the square steel pipe 30 ″ was uniform in the vertical direction, and the corner R portion could be formed in the same shape above and below the steel pipe 30 ″.

  Next, with reference to FIGS. 11A and 11B, a comparative example of the knowledge that the apex portion of the V-shaped section of the square steel pipe 30 ′ can be reshaped and formed into a flat long side in this embodiment. This will be explained in comparison with

  FIG. 11B shows a configuration of a comparative example in which the plate material 18 is removed from the configuration of the present embodiment shown in FIG.

  In the case of the comparative example shown in FIG. 11 (b), the upper mold 11 and the lower mold 12 are restricked over the entire long side of the square steel pipe 30 ', so that the apex of the square steel pipe 30' is swollen by spring back ( The amount of unevenness (LD) does not decrease, and the bulge (the amount of unevenness) LD of the apex portion of the square steel pipe 30 ″ after the second step often does not fall within the design tolerance range.

  On the other hand, in the case of the present embodiment shown in FIG. 11 (a), the apex of the square steel pipe 30 'is reshaped by the plate material 18, and the upper die 11 and the lower die 12 are the corner R portions of the square steel pipe 30'. , The bulge (uneven amount) LD at the apex of the square steel pipe 30 'is reduced, and the bulge (uneven amount) LD at the apex of the square steel pipe 30 "after the second step is ensured. It is within the design tolerance range.

  However, in order to surely eliminate the swelling of the apex, it is necessary to lower the upper mold 11 to a stroke position larger than the stroke position corresponding to the short side dimension LB in consideration of the spring back. .

  For example, it is assumed that a square steel pipe 30 ″ having the following product specifications is formed from the round steel pipe 30 having the following specifications by using the hydraulic press device 10 that generates a pressing press force of 500 tons. .

・ Before processing (round steel pipe 30)
Diameter: φ165.2
Plate thickness: 5.5t
After processing (square steel pipe 30 ″)
Size: 200 (LA) x 70 (LB)
Plate thickness: 5.5t
FIGS. 12A and 12B are views for explaining the stroke position of the upper mold 11 for manufacturing a product having the above specifications.

  That is, in the case of the above specifications, the upper die 11 is lowered from the stroke position (FIG. 12 (a)) corresponding to the short side dimension LB (70mm) to a stroke position further increased by 2mm (FIG. 12). (B)) A square steel pipe 30 ″ having a bulge (amount of irregularities) LD at the apex within the tolerance range could be formed.

  When a product having the above specifications is manufactured, as shown in FIG. 12C, the taper angle θ of the upper mold 11 and the lower mold 12 used in the first step is set to 80 ° to 83 °. If set, the corner portion of the long side of the square steel pipe 30 'was not buckled and did not bulge, and the corner R portion could be formed well.

(Second embodiment)
In the first embodiment described above, as shown in FIGS. 3 (a), 3 (b) and 11 (a), as the upper mold 11 and the lower mold 12 used in the second step, the corners of the steel pipe 30 'are used. Although what has the cross-sectional shape in which the site | part which opposes R part is dented is used, as shown in FIG.11 (b) as the upper mold | type 11 and the lower mold | type 12 which are used at a 2nd process. Moreover, you may use the upper mold | type 11 and the lower mold | type 12 which have a flat cross section with respect to the steel pipe 30 '.

  That is, as described in the first embodiment, when the upper die 11 and the lower die 12 shown in FIG. 11 (b) are used, the bulge (unevenness) LD at the apex of the square steel pipe 30 'is reduced by the springback. However, the bulge (unevenness) LD at the apex of the square steel pipe 30 ″ after the second process often does not fall within the design tolerance range, but the corner of the product specification has a large allowable width of the bulge at the apex. In the case of manufacturing a steel pipe, it is possible to use the upper mold 11 and the lower mold 12 shown in FIG. 11B in the second step.

(Third embodiment)
In the first embodiment described above, in the second step, as in the first step, the upper die 11 is moved toward the lower die 12 side, and in synchronization with this movement, the side dies 13, 14 are moved. However, in the second step, it is possible to remove the intermediate cam block 22 and fix the side molds 13 and 14 to the side of the upper mold 11 and the lower mold 12 without moving them synchronously. Good.

  That is, the corner R portion of the square steel pipe 30 ′ is formed in a substantially desired shape (desired radius R) by the first step. Therefore, in the second step, the side mold 13, 14 has little influence on the uniform formation of the upper and lower corners R of the square steel pipe 30 ″ and the formation of the uniform vertical shape of the square steel pipe 30 ″. For this reason, when the corner R portion of the square steel pipe 30 'already matches the product specifications only by the first step, the side molds 13 and 14 are not moved synchronously in the second step. The molds 13 and 14 may be fixed to the sides of the upper mold 11 and the lower mold 12.

(Fourth embodiment)
In the first embodiment described above, the side molds 13 and 14 are moved downward at 1/2 of the speed at which the upper mold 11 is moved downward (or approximately 1/2 speed). The moving speed of the upper mold 11 is not limited to this moving speed, and at least the descending mobility of the side molds 13 and 14 does not become zero, but does not become the same speed as the upper mold 11. It only has to be slower.

  That is, depending on the product specifications, the shape of the square steel pipe 30 ″ may be unevenly formed on the top and bottom, or the corner R portion may be formed in different shapes on the top and bottom of the steel pipe 30 ″. When manufacturing a square steel pipe 30 ″ having such product specifications, the lowering movement speed of the side molds 13 and 14 is set to 1/2 (or approximately 1/2) the lowering movement speed of the upper mold 11. It is also possible to set to a speed region shifted from (except for the zero speed and constant speed with the upper mold 11).

(5th Example)
In the first embodiment described above, the case where the square steel pipe 30 ″ is formed through the first process and the second process has been described. However, depending on the specifications of the product, the square steel pipe 30 after the first process is used. In addition, the bulge LD at the apex of the square steel pipe 30 'may be within an allowable range only by the first step due to other technical solutions due to future technological advances.

  In such a case, the second step may be omitted and only the first step may be performed.

  Further, in the above-described embodiment, the description has been made on the assumption that the press device 10 that performs the press work by lowering the upper die 11, but naturally the present invention is a press that performs the press work by raising the lower die 12. The present invention can also be applied to the device 10.

  In the present embodiment, the concept that the “side mold” is a lateral mold relative to the “upper mold” and the “lower mold” is clarified, and the correspondence between the claims and the terms in the embodiments is clarified. In order to take, the terms “upper mold” and “lower mold” were used, but “upper mold” and “lower mold” in the present invention are not necessarily limited to “up and down” in the vertical gravity direction, Of course, the present invention also applies to a configuration in which “upper mold” and “lower mold” are arranged in an arbitrary direction (for example, horizontal horizontal direction) and “side mold” is arranged on the side (vertical gravity direction). It is possible, and the terms “upper mold” and “lower mold” in the claims are also interpreted in such a meaning.

  In the above-described embodiment, the case where the steel pipe 30 is formed has been described. However, the material of the pipe that is a target in the present invention may be formed from a round tube to a square tube (plastic deformation) by pressing. Any material can be used as long as it can be used without being limited to steel.

FIG. 1 is a cross-sectional view illustrating a configuration of a press apparatus according to an embodiment. FIGS. 2A and 2B are diagrams illustrating the first step. 3A and 3B are diagrams for explaining the first step. 4 (a), 4 (b), and 4 (c) are views showing how the steel pipe is deformed in the first step. FIGS. 5A, 5 </ b> B, and 5 </ b> C are diagrams illustrating a comparative example that is compared with the embodiment. FIGS. 6A, 6 </ b> B, and 6 </ b> C are diagrams illustrating a comparative example that is compared with the embodiment. FIGS. 7A, 7B, and 7C are diagrams for explaining the embodiment corresponding to FIGS. FIGS. 8A, 8B, and 8C are diagrams for explaining a comparative example to be compared with the embodiment. FIGS. 9A, 9B, and 9C are diagrams for explaining the embodiment corresponding to FIG. FIGS. 10A and 10B are views for explaining the size of the cross section of the steel pipe. FIGS. 11A and 11B are diagrams showing the configuration of the upper mold and the lower mold used in the second step. FIGS. 12A, 12B, and 12C are diagrams for explaining the upper mold, the lower taper angle, and the upper mold stroke used in the embodiment. FIG. 13 is an explanatory diagram of the prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Press apparatus 11 Upper type | mold 12 Lower type | mold 13, 14 Side type | mold 30 Round steel pipe, 30 'square steel pipe 30 "square steel pipe

Claims (11)

A method of manufacturing a square tube, in which a round tube is set between an upper die and a lower die of a press device, and the round tube is formed into a square tube,
The upper mold and the lower mold having a V-shaped cross section recessed with respect to the pipe are installed in the press device,
While moving one of the upper mold and the lower mold toward the other mold side, the side mold is moved to the other mold so that the contact point where the side mold contacts the pipe moves in synchronization with this movement. Move it at a speed slower than the mold speed,
A method of manufacturing a square tube using a press device, wherein the cross section of the tube is formed into a shape having a corner R portion. A method of manufacturing a square tube, in which a round tube is set between an upper die and a lower die of a press device, and the round tube is formed into a square tube,
In the first step,
The upper mold and the lower mold having a V-shaped cross section recessed with respect to the pipe are installed in the press device,
While moving one of the upper mold and the lower mold toward the other mold side, the side mold is moved to the other mold so that the contact point where the side mold contacts the pipe moves in synchronization with this movement. Move it at a speed slower than the mold speed,
The cross section of the tube is shaped into a shape having a V-shaped long side corresponding to the cross-sectional shape of the upper die and the lower die, and having a corner R portion,
In the second step,
Lisk-like the top of the V-shaped section of the tube, and install the upper and lower molds to form a flat long side in the press device,
Move one of the upper and lower molds toward the other mold,
A method of manufacturing a square tube using a press device, characterized in that a cross section of the tube is formed into a rectangular shape. In the second step, the upper mold and the lower mold installed in the press machine are
The method for manufacturing a square tube using a press device according to claim 2, wherein the tube has a recessed cross-sectional shape facing a corner R portion of the tube. In the second step, one of the upper mold and the lower mold is moved toward the other mold side, and in synchronization with this movement, the contact point where the side mold contacts the pipe moves. The method of manufacturing a square tube using a press device according to claim 2, wherein the side mold is moved at a speed slower than the speed of the one mold. Synchronize the side mold with one of the upper and lower molds facing the other mold so that the contact point where the side mold contacts the pipe is maintained at the midpoint between the upper and lower molds. The manufacturing method of the square tube using the press apparatus of Claims 1-4 characterized by the above-mentioned. 6. A method of manufacturing a square tube using a press apparatus according to claim 1, wherein the side mold is moved at a speed that is ½ of the moving speed of either the upper mold or the lower mold. . A pressing device that performs a pressing process for setting a round tube between an upper die and a lower die and forming the round tube into a square tube,
An upper die and a lower die having a concave V-shaped cross section with respect to the tube;
Side molds arranged on the sides of these upper mold and lower mold,
In synchronization with the movement of one of the upper mold and the lower mold toward the other mold side, the side mold is moved faster than the speed of the one mold so that the contact point where the side mold contacts the pipe moves. And a synchronizing mechanism for moving at a slow speed. A press device for forming a round tube into a square tube through a first step and a second step subsequent thereto,
In the first step,
An upper die and a lower die having a concave V-shaped cross section are installed in the press device with respect to the pipe,
The cross section of the tube has a V-shaped long side corresponding to the cross-sectional shapes of the upper mold and the lower mold, and is molded into a shape having a corner R portion,
In the second step,
An upper die and a lower die for forming a flat long side by re-slicing the apex of the V-shaped section of the tube formed by the first step are installed in the press device,
The press device according to claim 7, wherein a cross section of the tube is formed in a rectangular shape. In the second step, the upper mold and the lower mold installed in the press machine are
The press device according to claim 8, wherein the press device has a cross-sectional shape in which a portion facing the corner R portion of the tube is recessed. The synchronization mechanism is
Synchronize the side mold with one of the upper and lower molds facing the other mold so that the contact point where the side mold contacts the pipe is maintained at the midpoint between the upper and lower molds. The method of manufacturing a square tube using the press device according to claim 7, wherein the mechanism is a mechanism for moving the tube. The synchronization mechanism is
The press device according to any one of claims 7 to 10, wherein the pressing device is a mechanism that moves the side die at a speed that is ½ of the moving speed of either the upper die or the lower die.

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