JP4810122B2 - Outer mast tie beam and structural material manufacturing method for forklift - Google Patents

Description

  The present invention relates to a structural material and a method of manufacturing the same, and more specifically, a structural material that has a bent portion and is used by being joined to another structural material by welding or the like at a part of the bent portion, for example, an outer mast in a forklift. The present invention relates to a structural material suitable for a tie beam and a manufacturing method thereof.

  As shown in FIG. 6, the outer mast structure in the forklift includes a pair of left and right outer masts 31 having a U-shaped cross section, which are mounted on the front part of the vehicle body, connected by a tie beam 32. The tie beam 32 is provided with bent portions 33 at both ends, and is joined to the upper end side wall and the rear wall of the outer mast 31 by welding on the distal end side of the bent portion 33. Further, the base end portion of the chain anchor plate 34 is welded to the outer mast 31 to the side wall of the outer mast 31. In order to reinforce the chain anchor plate 34, the chain anchor plate 34 and the tie beam 32 are welded and joined by a connecting bracket 35 (see, for example, Patent Document 1).

Conventionally, the tie beam 32 of the forklift has been formed by fusing a steel plate having the same thickness as the tie beam 32. However, the method of forming the tie beam 32 by fusing from a steel plate has a problem that the yield in forming the tie beam 32 is poor.
Japanese Patent Laying-Open No. 2004-210500 (paragraph [0002] of the specification, FIG. 7)

  As a method for improving the poor yield when forming the tie beam 32 from a steel plate, the applicant of the present application considers and implements the tie beam 32 by bending flat steel. However, when the tie beam 32 is manufactured by bending a flat steel by a general bending process, as shown in FIG. 7, bulged portions 33 a are formed on the upper and lower surfaces of the bent portion 33 of the tie beam 32. Therefore, there is a problem that it is difficult to manage the gap when the bent portion 33 of the tie beam 32 and the upper end portion of the connection bracket 35 are joined by welding.

The present invention has been made in view of the above-described conventional problems. The first object of the present invention is to eliminate the need for gap management when connecting to other structural materials at the bent portion, thereby facilitating the connection. Another object of the present invention is to provide an outer mast tie beam in a forklift that can improve the yield of the material as compared with the case where the steel plate is manufactured by fusing a steel plate. Moreover, the 2nd objective is to provide the manufacturing method of the structural material which can improve the yield of material compared with the case where it manufactures by fusing of a steel plate.

To achieve the first object, a first aspect of the present invention, bent portions are provided at both ends of the cross-section rectangular metal bar Rutotomoni, the bending portion is straight portion of the metal rod A tie beam of an outer mast in a forklift formed so as to be bent on the same side with respect to the inner surface of the bent portion, and a bulging portion on the inner surface of the bent portion, and the inner surface and the outer surface of the side surfaces of the bent portion in a first side and a second side is a plane portion of the bending portion excluding, as well as have a bulging portion on the second side of the planar portion of the bent portion, the planar portion of the bent portion Of these, the first side surface is a portion that is coupled to another structural material, and the first side surface is a flat surface that does not bulge. The metal bar is preferably made of steel, but it may be made of a material other than steel depending on the required strength. The “planar portion of the bent portion” means a surface parallel to a plane perpendicular to the central axis of curvature of the bent portion.

The tie beam of the outer mast in the forklift of the present invention is used by being joined to another structural material by welding or the like in a state where the other structural material is in contact with the side where the bent portion does not have the bulging portion, that is, a flat surface. The outer mast tie beam in a forklift that has been bent by a simple bending method has bulges on both flat surfaces of the bent part, so when connecting with other structural materials by welding, etc., management of the gap at the contact point Is difficult. However, the tie beam of the outer mast in the forklift according to the present invention has a flat surface with no bulging portion on the other flat portion of the bent portion. No management is required and coupling becomes easy. Moreover, the yield of material can be improved compared with the case where it manufactures by fusing a steel plate.

Moreover , the said bending part is formed so that it may bend in the same side with respect to the linear part of the said metal bar, while being provided in the both ends of the said metal bar. In this configuration , when the bent portion is manufactured by bending, the yield of the material can be further improved as compared with the case where the bent portion is manufactured by fusing the steel plate.

Further, Tybee arm of the outer mast in forklift, flat portions no bulge portion, i.e. the flat surface is bonded by welding to the outer mast such that the lower side, the flat surface, for reinforcement of the chain anchoring plate, chain It is welded to a connecting bracket that is connected between the anchor plate and the tie beam. In that case, gap management becomes unnecessary and welding becomes easy. Moreover, when it manufactures so that a bending part may be formed by a bending process, the yield of material can be improved compared with the case where it manufactures by fusing of a steel plate.

In order to achieve the second object, the invention according to claim 2 is a method of manufacturing a structural material having a bent portion in a metal bar having a square cross section. When the metal bar is bent, the metal bar is placed on the lower mold so that the center of curvature of the bent portion is on the upper side. The upper die having a curvature corresponding to the curved shape of the bent portion and provided with a restricting portion that abuts on the metal rod and regulates the movement of the metal rod to the upper die side. The bar material is pressed to bend the metal bar. When bending is performed, the metal bar is allowed to bulge to the inside of the bent portion and one flat portion of the bent portion, and the bulge to the other flat portion of the bent portion is restricted. There rows bending state, the upper mold includes a regulating surface for regulating the swelling of the first side of the bending the metal bar placed on the lower mold during the regulation A bulging permissible surface that is provided on the side facing the surface and is formed so that the distance from the regulation surface is closer to the lower mold, and is continuous with the ends of the regulation surface and the bulge permissible surface. And a bulging allowing portion that is provided at a position sandwiched between the restricting portions and allows the bulging to the inside of the bending portion during the bending process .

  In the manufacturing method of the present invention, when bending a metal bar, the metal bar is allowed to bulge to the inside of the bent portion and bulge to one flat portion side of the bent portion. It is pressed by the upper mold in the state. Therefore, unlike the conventional bending process, the bulging part is not substantially formed in the other plane part of the bending part in a state where the bending process is completed. “Substantially not formed” means that even if the presence of a bulging part is recognized by observation with a microscope or the like, there is no need for gap management when joining in contact with other structural materials. Means. Moreover, the yield of material can be improved compared with the case where the structural material which has a bending part is manufactured by fusing a steel plate.

Moreover, the metal rods are prevented from bulging of the sides since the first side face (corresponding to the flat portion of the other side) is bent in contact with state regulation surface of the upper mold, facing the regulating surface Swelling occurs on the side opposite to the side. In addition, since the metal bar is bent while being pressed by the restricting portion provided on the upper mold so that the metal bar exists on both sides of the bulging allowance part, the bending force is applied to the metal bar. While acting without being biased, the bulging inward of the bent portion is performed smoothly.

According to the first aspect of the present invention, it is not necessary to manage gaps when joining with other structural materials at the bent portion, and the joining becomes easy, and the material is made in comparison with the case where it is manufactured by fusing the steel plate. Yield can be improved. Moreover, according to the invention of Claim 2 , the yield of material can be improved compared with the case where it manufactures by fusing of a steel plate.

  Hereinafter, an embodiment in which the present invention is embodied in an outer mast tie beam in a forklift will be described with reference to FIGS. FIG. 1A is a schematic plan view of a tie beam, and FIG. 1B is a partial front view. 2A is a schematic front view showing the relationship between a metal mold for performing bending and a metal bar, FIG. 2B is a schematic cross-sectional view taken along line AA in FIG. 3A, and FIG. The model front view which shows the relationship between the metal mold | die and the metal bar in the state in which the process was performed, (b) is a schematic cross section in the BB line of (a). FIG. 4 is a schematic cross-sectional view showing the upper mold of the prior art.

  As shown in FIG. 1A, a tie beam 11 as a structural material is provided with bent portions 13 at both ends of a metal bar 12 having a square cross section. A suspension hole 14 is formed in the bent portion 13. Engagement recesses 15 for coupling with the outer mast are provided on the inner side of the ends of the bending portions 13 of the tie beam 11. A flat steel is used as the metal bar 12.

  As shown to Fig.1 (a), the bending part 13 has the bulging part 13a inside. As shown in FIG. 1 (b), the bending portion 13 also has a bulging portion 13b on one flat surface portion (portion on the upper side when coupled to the outer mast). The other plane portion is a flat portion 13c that is a flat surface that does not bulge. In FIGS. 1A and 1B, the bulging portions 13a and 13b are exaggerated for easy understanding.

  Next, a method for manufacturing the tie beam 11 configured as described above will be described. The tie beam 11 is formed by bending a flat steel. As shown in FIGS. 2 (a), 2 (b) and 3 (a), 3 (b), a lower die (die) 21 used for bending is a gold used for V-bending generally called bevel bending. A mold similar to the mold is used. The lower die 21 has a V groove 21a, and a restriction groove 22a for restricting movement of the material 20 that is a metal bar in the width direction extends in a direction perpendicular to the V groove 21a on the upper surface of the material placement portion 22. It is provided as follows. The material 20 is placed on the material placement portion 22 in a state where a part of the material 20 is engaged with the restriction groove 22a.

  As shown in FIG. 2A and FIG. 3A, the upper mold 23 is formed in a shape corresponding to the V groove 21 a of the lower mold 21 at the tip (lower end) as a front shape. As shown in FIG. 2B and FIG. 3B, the upper mold 23 has the material 20 bent during the bending process in the width direction, that is, perpendicular to the paper surface of FIG. 2A and FIG. 3A. A groove 24 for restricting movement in the direction and accommodating the upper side of the material 20 is provided. The depth of the groove 24 is formed so as to cover almost the entire side surface of the material 20 at a location corresponding to the bent portion. The groove 24 is provided on the side facing the regulating surface 24a and the regulating surface 24a that regulates the bulging of one side surface of the material 20 placed on the lower mold 21 during bending, and the distance between the regulating surface 24a. Has a bulging allowance surface 24b formed so as to be longer toward the side closer to the lower die 21. The regulating surface 24a is formed as a plane perpendicular to the horizontal plane, and the bulging allowance surface 24b is formed as a plane inclined with respect to the vertical plane.

  Restriction portions 24c and 24d that abut the upper surface of the material 20 during bending and restrict the movement of the material 20 to the upper mold side are formed so as to be continuous with the upper end portions of the restriction surface 24a and the bulging allowance surface 24b. Yes. A bulging allowing portion 24e that allows bulging to the inside of the bent portion during bending is provided at a position between the restricting portions 24c and 24d.

Next, the operation when the material 20 is bent using the lower mold 21 and the upper mold 23 configured as described above will be described. Bending is performed one side at a time.
First, the material 20 is placed on the lower mold 21. As the material 20, a flat steel cut into a predetermined length is used.

  Next, the upper die 23 is lowered, and the upper side of the portion that becomes the center of the bent portion of the material 20 is relatively moved into the groove 24 of the upper die 23 with the lowering. Then, as shown in FIGS. 2A and 2B, when the upper mold 23 continues to descend from the state where the restricting portions 24 c and 24 d are in contact with the upper surface of the material 20, the restricting portion is placed on the upper surface of the material 20. The material 20 is bent by pressing force from the upper mold 23 via 24c and 24d. When the material 20 is bent until the bending angle reaches 90 degrees, the state shown in FIGS. 3A and 3B is reached, and the lowering of the upper mold 23 is completed.

In addition, after the bending process is performed, the suspension hole 14 and the engagement recess 15 are processed.
When the material 20 is bent, a tensile stress acts outside the neutral axis of the material 20 and a compressive stress acts inside the neutral axis. A part of the material tends to swell due to the action of compressive stress. Since the material 20 is bent in a state where the first side surface 20a is in contact with the regulation surface 24a, the occurrence of the bulging portion on the first side surface 20a in contact with the regulation surface 24a is regulated. However, the second side surface 20b of the material 20 is bent in a state facing the bulging allowance surface 24b, and there is a gap between the second side surface 20b and the bulging allowance surface 24b. A bulging portion 13b is formed on the side surface 20b.

  Further, the material 20 is subjected to a force to swell at a portion corresponding to the inner side surface 20c of the bent portion. In the prior art, as shown in FIG. 4, as the upper mold 23, there is no bulging allowable portion, and a material having a convex portion 25 in a portion facing the upper surface of the material 20 is used. The bulging portion 13a is prevented from occurring on the inner side surface 20c. As a result, the bulging part resulting from the compressive stress also occurred on the regulation surface 24a side.

  However, since the upper mold 23 used in this embodiment has the bulging allowance 24e sandwiched between the restricting portions 24c and 24d, the material 20 has a portion facing the bulge allowance 24e, That is, when the bulging portion 13a is generated inside the bent portion, the occurrence of the bulging portion at a portion corresponding to the regulation surface 24a of the material 20 is avoided.

  The tie beam 11 manufactured as described above is welded between a pair of outer masts in a state where the engaging recess 15 is engaged with the outer mast in a state where the bulging portion 13b generated in the flat portion of the bending portion 13 is on the upper side. Combined with And it joins with the connection bracket for chain anchor plate reinforcement in the flat part 13c of the bending part 13 in which the bulging part 13b does not arise.

This embodiment has the following effects.
(1) The tie beam 11 is provided with a bent portion 13 at an end portion of a metal bar 12 having a quadrangular cross section, and bulging portions 13 a and 13 b are provided on the inner side of the bent portion 13 and one flat portion of the bent portion 13. The other flat portion is a flat portion 13c that does not bulge. Accordingly, the connecting portion for reinforcing the chain anchor plate is in contact with the flat portion 13c on the surface of the bent portion 13 where the bulging portion 13b is not present, and is used by being combined with another structural material by welding or the like. This eliminates the need for gap management when joining and facilitates joining. Moreover, the yield of the material 20 can be improved compared with the case where it manufactures by fusing a steel plate.

  (2) When the tie beam 11 is manufactured, the material 20 that is a metal bar is placed on the lower mold 21 so that the center of curvature of the bent portion is on the upper side when the bending process is performed. Then, the material 20 is pressed by the upper die 23 having a curvature corresponding to the curved shape of the bending portion and provided with restriction portions 24c and 24d that abut against the material 20 and restrict the movement of the material 20 to the upper die side. The material 20 is then bent. When the bending process is performed, the bending process is performed in a state in which the material 20 is allowed to bulge to the inside of the bending part and to one plane part of the bending part. Therefore, unlike the conventional bending process, the bulging part is not substantially formed in the flat part 13c which is the other flat part of the bending part 13 in a state where the bending process is completed.

  (3) The upper die 23 is provided on the side facing the regulating surface 24a and the regulating surface 24a that regulates the bulging of the first side surface 20a of the material 20 placed on the lower die 21 during bending. The bulging allowance surface 24b is formed so that the distance from the regulation surface 24a is longer toward the side closer to the lower mold 21. The restriction portions 24c and 24d formed so as to be continuous with the end portions of the restriction surface 24a and the bulging allowance surface 24b, and the inside of the bending portion 13 at the time of bending work are provided at positions sandwiched between the restriction portions 24c and 24d. And a bulging permissible portion 24e that allows the bulging to occur. Accordingly, since the material 20 is bent in a state where the first side surface 20a is in contact with the upper regulating surface 24a, the bulging of the first side surface 20a is prevented, and the material 20 is opposite to the side surface facing the regulating surface 24a. Swelling occurs on the side surface, that is, the second side surface 20b. Further, since the metal rod 12 is bent while being pressed by the restricting portions 24c and 24d provided on the upper mold so as to exist on both sides of the bulging allowance portion 24e, the metal rod 12 The bending force acts on the material 12 without being biased, and the bending portion 13 is smoothly bulged inward.

The embodiment is not limited to the above, and may be configured as follows, for example.
The upper mold 23 is a material that comes into contact with the material 20 and a regulating surface 24a that regulates the bulging of the first side surface 20a of the material 20 having a quadrangular section placed on the lower mold 21 during bending. It is only necessary to include a restricting portion that restricts the movement of the upper 20 toward the upper mold 23 and a bulging permissible portion 24e that allows bulging to the inside of the bent portion during bending. Therefore, the shape of the groove 24 provided in the upper mold 23 is not limited to the shape of the above embodiment. For example, instead of the restricting portions 24c and 24d made of a horizontal plane, as shown in FIG. It is good also as a substantially trapezoid shape whose width becomes narrower.

  The restriction part that abuts on the material 20 and restricts the movement of the material 20 toward the upper mold 23 may exist only on one side of the restriction surface 24a side and the bulging allowance surface 24b side. For example, as shown in FIG. 5B, the cross-sectional shape of the bulging allowance 24e is such that the surface continuous to the restricting surface 24a extends vertically on the same plane as the restricting surface 24a and continues to the bulging allowable surface 24b. The surface may be formed in a trapezoidal shape having an inclined surface having a larger angle with the vertical surface than the bulging allowable surface 24b. Further, as shown in FIG. 5C, the cross-sectional shape of the bulging allowance portion 24e is such that the surface continuing to the restricting surface 24a extends vertically on the same plane as the restricting surface 24a, and the horizontal surface on the bulging allowance surface 24b side. You may form in the rectangular shape which has a vertical surface which continues to the control part 24d which consists of. In these cases, the restricting portion 24d exists only on the bulging allowance surface 24b side.

  ○ The angle formed by the straight portions existing on both sides of the bent portion 13 is not limited to 90 degrees. Further, even when the angle formed by the straight portions existing on both sides of the bent portion 13 is 90 degrees, the angle of the V groove 21a of the lower mold 21 may not be 90 degrees.

  The angle of the V-shaped groove 21a of the lower mold 21 is not limited to a shape that is in surface contact with a part of the linear portion that is continuous on both sides of the bent portion of the material 20 with the bending of the material 20 being completed. In other words, the V groove 21a may be configured to serve only as a space allowing the material 20 to be bent. Therefore, a groove having a shape other than the V groove 21a may be provided.

  ○ In place of the regulation groove 22a in the material placement part 22 of the lower mold 21, a regulation convex part is provided at the same interval as the width of the material 20, or the movement in the width direction is regulated by contacting only one side of the material 20. You may provide a control part. Further, the material placement portion 22 may be a flat surface without providing a restriction portion that restricts the movement of the material 20 in the width direction.

  The structural material is not limited to the tie beam 11 of the forklift, but may be a structural material that has a bent portion and is used by being joined to another structural material by welding or the like at a part of the bent portion. The connection with other structural members is not limited to welding, and may be a connection using bolts.

  In the case of a structural material other than the tie beam 11 of the forklift, the bent portions 13 provided at both ends of the metal bar 12 are formed so as to be bent to the same side with respect to the straight part of the metal bar 12. Not limited to this, a structure formed so as to be bent to the opposite side with respect to the straight portion may be used. Further, the shape is not limited to the shape in which the bent portions 13 are provided at both ends of the metal rod 12, and the structure in which the bent portions are provided on one end side of the metal rod 12 may be used.

The following technical idea (invention) can be understood from the embodiment.
(1) before Symbol metal rod is made of a flat steel.

(A) is a schematic plan view of a tie beam, (b) is a partial enlarged front view of (a). (A) is a schematic front view which shows the relationship between the metal mold | die and metal bar which perform a bending process, (b) is a schematic cross section in the AA of (a). (A) is a schematic front view which shows the relationship between the metal mold | die and the metal bar in the state in which the bending process was performed, (b) is a schematic cross section in the BB line of (a). The schematic cross section which shows the upper mold | type of a prior art. (A)-(c) is a schematic cross section which shows the upper mold | type of another embodiment. The schematic perspective view which looked at the tie beam structure of the prior art from the back side. The partial schematic front view of the tie beam which shows the bulging state in a bending part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Tie beam, 12 ... Metal rod, 13 ... Bending part, 13a, 13b ... Protruding part, 13c ... Flat part as a flat surface, 20a ... 1st side surface, 21 ... Lower mold | type, 23 ... Upper mold | type, 24a ... regulating surface, 24b ... bulging permissible surface, 24c, 24d ... regulating portion, 24e ... bulging permissible portion.

Claims (2)

Bent portions provided at both ends of the cross-section rectangular metal bar Rutotomoni, the bends ties of outer masts the forklift that is formed to be bent on the same side of the linear portion of the metal rod Because
A bulging portion on the inner surface of the bent portion ;
The first side surface and the second side surface, which are the flat surface portions of the bent portion excluding the inner side surface and the outer surface, of the side surfaces of the bent portion, bulge to the second side surface among the flat surface portions of the bent portion. as well as have a part, of the outer masts in the forklift of the first aspect the first side is a moiety attached to other structural member is a flat surface that does not bulge out of the plane portion of the bent portion Thai beam . A method of manufacturing a structural material having a bent portion in a metal bar having a square cross-section, wherein the metal bar is bent so that the center of curvature of the bent portion is on the upper side when the metal bar is bent. With the bar material placed on the lower mold, the metal bar has a curvature corresponding to the curved shape of the bent portion and moves to the upper mold side in contact with the metal bar. The metal bar is pressed by an upper mold having a regulating part to be regulated to bend the metal bar, and when bending, to the inside of the bent part and one flat part of the bent part wherein while permitting swelling of the metal bar, have rows bending in a state of restricting the bulge to the other planar portion of the bent portion of,
The upper mold is provided on a regulation surface that regulates bulging on the first side surface of the metal bar placed on the lower mold during the bending process, and on a side facing the regulation surface. The bulging allowance surface formed such that the distance from the restricting surface is closer to the side closer to the lower mold, and the restricting portion formed so as to be continuous with the end portions of the restricting surface and the bulging allowance surface. And a swellable portion that is provided at a position sandwiched between the restricting portions and allows bulging to the inside of the bent portion during the bending process.

Images