JP2011255986A - Method for manufacturing crane jib - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate manufacturing of a crane jib.SOLUTION: A method for manufacturing of a crane jib is provided for forming long and hollow support parts 21 serving as a crane jib 2 by welding the long plate members 21b to an opening part of body members 21a with respect to the long body members 21a formed by having a side part opened along the longitudinal direction L. The method includes: a temporary assembling step of temporarily assembling the support parts 21 by welding the plate members 21b to the body members 21a temporarily; a bending step of arranging the two support parts 21 in parallel and binding the two support parts 21 each other while being bent in the directions opposite to the directions of distortion expected in final welding; and a final welding step of carrying out final welding simultaneously to the two support parts 21 while being bound together.

Description

  The present invention relates to a crane jib manufacturing method for manufacturing a crane jib.

  For example, in a deck crane, a turning post is provided on a fixed post so as to be turnable. The swivel post is provided with a crane jib. The crane jib is configured by connecting two long support portions to each other. The two support portions are provided so that each base end is supported by a turning post and can swing up and down. The crane jib is lifted by winding or unwinding the wire with a lifting winch provided on the turning post (see, for example, Patent Document 1).

JP-A-10-101292

  By the way, like the deck crane described in the above-mentioned Patent Document 1, a crane jib composed of two support parts needs to be lightened and stiff for the purpose of raising and lowering. The pair of support portions constituting the structure is a hollow structure to reduce weight and increase rigidity.

  The hollow long support portion is manufactured by welding and joining a plurality of members, but after welding, distortion occurs due to thermal contraction of the welded portion, and the long support portion is curved and deformed. For this reason, conventionally, a manufacturing method that suppresses the curved deformation of the support portion by constraining the support portion or welding with a reverse strain applied has been adopted, but since the curved deformation still occurs, The support part was heated with a gas burner and the strain was removed by water cooling. In this case, it is necessary to correct the distortion after forming the support portion. As a result, in manufacturing the crane jib, much labor is required, and the manufacturing cost increases.

  This invention solves the subject mentioned above, and aims at providing the crane jib manufacturing method which can manufacture a crane jib easily.

  In order to achieve the above-described object, the crane jib manufacturing method of the present invention has a long plate at the opening portion of the main body member with respect to the long main body member formed by opening the side portion along the longitudinal direction. A crane jib manufacturing method for forming a long hollow support portion that forms a crane jib by welding members, wherein the main body member and the plate member are temporarily welded to temporarily assemble the support portion; and A bending step of restraining the two support portions in a state in which the two temporarily assembled support portions are juxtaposed, and bending is applied in a direction opposite to the expected distortion due to the main welding, and the restrained state of the 2 And a main welding step of simultaneously performing main welding of two support portions.

  According to this crane jib manufacturing method, in the state where the support portion is temporarily assembled, the support portion is previously bent in the opposite direction to the expected strain due to the main welding, so that the distortion due to the heat shrinkage after the main welding is sufficient. It is possible to absorb. In addition, since the two temporarily assembled support portions are arranged side by side to bend each support portion, it is possible to equally apply bending to the two support portions forming the crane jib. In addition, when the main welding is performed simultaneously on the two support parts, opposite strain stresses due to thermal shrinkage are equally generated on the two support parts, and welding is performed for each support part. Compared to this, it becomes possible to make the shape much straighter, and the occurrence of distortion in each support portion which has been restrained can be minimized. As a result, the crane jib can be easily manufactured.

  Further, the crane jib manufacturing method of the present invention is characterized in that after the main welding step, the support portion is rotated in a restrained state, and then main welding of other welding portions of the two support portions is simultaneously performed. And

  According to this crane jib manufacturing method, by rotating the support portion in a constrained state, it is possible to arrange another welding site at a position where it is easy to perform the main welding. For this reason, the main welding operation can be easily performed. As a result, the crane jib can be easily manufactured.

  According to the present invention, a crane jib can be easily manufactured.

FIG. 1 is a schematic side view of a deck crane having a crane jib according to an embodiment of the present invention. FIG. 2 is a schematic plan view of the deck crane shown in FIG. FIG. 3 is a schematic perspective view showing a wire of the deck crane shown in FIG. FIG. 4 is a schematic cross-sectional view (an enlarged cross-sectional view taken along the line AA in FIG. 2) showing the crane jib according to the embodiment of the present invention. FIG. 5 is a schematic view showing a manufacturing process of the crane jib according to the embodiment of the present invention. FIG. 6 is a schematic view showing a manufacturing process of a crane jib according to the embodiment of the present invention. FIG. 7 is a schematic view showing a manufacturing process of a crane jib according to the embodiment of the present invention. FIG. 8 is a schematic view showing a manufacturing process of the crane jib according to the embodiment of the present invention. FIG. 9 is a schematic view showing a manufacturing process of a crane jib according to the embodiment of the present invention. FIG. 10 is a schematic view showing another method for manufacturing the crane jib according to the embodiment of the present invention.

  Embodiments according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  1 is a schematic side view of a deck crane having a crane jib according to the present embodiment, FIG. 2 is a schematic plan view of the deck crane shown in FIG. 1, and FIG. 3 is a diagram of the deck crane shown in FIG. It is a schematic perspective view which shows a wire.

  As shown in FIGS. 1 and 2, the deck crane is provided with a crane jib (hereinafter simply referred to as a jib) 2 on a swing post 1. The swivel post 1 is provided to be rotatable around an axis S with respect to the fixed post 4 fixed to the deck 3. The swivel post 1 is swiveled around the axis S by a drive mechanism (not shown).

  Further, the swivel post 1 is provided with a lifting winch 5 and a hoisting winch 6 on the lower side thereof. Moreover, the swivel post 1 is provided with five pulleys 7a to 7e at its upper end.

  The jib 2 is formed long. The jib 2 has a base end attached to the lower side of the swivel post 1 via a horizontal shaft 2a, and is provided so as to be swingable up and down. Specifically, the jib 2 is formed in an A shape in a plan view when two support portions 21 formed in a long shape are connected in parallel and connected by a connection portion 22. The proximal end is attached to the swivel post 1 via a shaft 2a.

  The jib 2 is provided with five pulleys 7f to 7j at the upper end of the tip. Moreover, the jib 2 is provided with one pulley 7k at the middle upper part thereof.

  As shown in FIG. 3, the wire 8a wound around the hoisting winch 5 includes a pulley 7b on the turning post 1 side, a pulley 7g on the tip end side of the jib 2, a pulley 7c on the turning post 1 side, and a pulley 7k on the intermediate side of the jib 2. The tip is fixed to the swivel post 1. The wire 8a is pulled up by winding the hoisting winch 5 to pull up the pulley 7g on the tip side of the jib 2 and the pulley 7k on the intermediate side. For this reason, the jib 2 swings upward about the shaft 2a, and the tip rises. On the other hand, when the wire 8a is drawn out by the lifting winch 5, the wire 8a is loosened, and the pulley 7g on the tip side of the jib 2 and the pulley 7k on the intermediate side are suspended. For this reason, the jib 2 swings downward about the shaft 2a, and the tip is lowered. In this way, the jib 2 is lifted by winding or unwinding the wire 8a by the lifting winch 5.

  As shown in FIG. 3, the wire 8b wound around the lifting winch 6 includes a pulley 7a on the revolving post 1 side, a pulley 7f on the tip end side of the jib 2, a pulley 9a provided on a lifting member 9 including a hook and the like. 2 A pulley 7j on the tip side, a pulley 7e on the swivel post 1 side, a pulley 7i on the tip side of the jib 2, a pulley 7d on the swivel post 1 side, and a pulley 7h on the tip side of the jib 2 are bridged in this order. It is fixed to. And the wire 8b is pulled by winding up the wire 8b with the raising / lowering winch 6, and the pulley 9a is pulled up. For this reason, the elevating member 9 rises at the lower end of the jib 2 tip. On the other hand, when the wire 8b is drawn out by the lifting winch 6, the wire 8b is loosened and the pulley 9a is suspended. For this reason, the elevating member 9 is lowered at the lower end of the jib 2 tip. In this way, the elevating member 9 moves up and down by winding or unwinding the wire 8b by the elevating winch 6. That is, the load can be raised and lowered by attaching a load (not shown) to the lifting member 9.

  And the load attached to the raising / lowering member 9 can be moved by the turning of the turning post 1, the raising / lowering of the jib 2, and the raising / lowering of the raising / lowering member 9. The turning of the turning post 1, the raising / lowering of the jib 2, and the raising / lowering of the elevating member 9 are operated by an operator in the cockpit 1 a provided in the turning post 1.

  FIG. 4 is a schematic cross-sectional view (an enlarged cross-sectional view taken along the line AA in FIG. 2) showing the crane jib according to the present embodiment. As shown in FIG. 4, the two support portions 21 constituting the jib 2 include a long main body member 21 a having a substantially U-shaped cross section formed by opening a side portion along the longitudinal direction, and a main body member 21 a. It is comprised with the elongate board member 21b fixed to the opening part. By comprising in this way, since the support part 21 is formed in elongate hollow, the jib 2 can be reduced in weight and rigidity.

  In order to fix the plate member 21b to the main body member 21a, a groove is provided at the opening end of the main body member 21a, and the plate member 21b is welded 10 to the groove portion. However, when the plate member 21b is fixed to the side portion of the main body member 21a by the welding 10, the side portion of the main body member 21a contracts due to the cooling after the welding 10 and is distorted, and is bent in an arc shape to the side. In particular, since the support portion 21 is about 30 m long, for example, a distortion difference between the tip and the center portion is about 300 mm.

  Therefore, the crane jib manufacturing method of the present embodiment is for easily forming the support portion 21 while correcting the distortion. 5-9 is schematic which shows the manufacturing process of the crane jib which concerns on this Embodiment.

  First, as shown in FIG. 5, the main body member 21a and the plate member 21b are temporarily assembled by temporary welding 11 (temporary assembly step). Then, two temporarily assembled support portions 21 are prepared.

  Next, as shown in FIG. 6, the two temporarily assembled support portions 21 are arranged side by side so that the plate member 21 b side is opposite to the support member 21 in the opposite direction of the expected distortion due to the subsequent main welding 10. On the other hand, bending (reverse strain) is applied (bending step). In this bending process, the holding mechanism 100 and the horizontal jack 200 are used.

  The holding mechanism 100 is arranged on the work floor, and is a mode in which the holding unit 110 that holds the end portions of the support units 21 of the temporary assembly arranged side by side and the top and bottom of the support units 21 arranged side by side are reversed. And a rotating part 120 that rotates at the same time. The holding part 110 holds the support part 21 by sandwiching the end part of the support part 21. The rotating unit 120 includes a rotating base 121 that rotatably supports the holding unit 110 with a horizontal axis along the longitudinal direction L of the support unit 21, a driven gear 122 provided on the holding unit 110, and a motor 123. 123, a driving gear 123a and a driven gear 122 are connected by a chain. The rotating unit 120 rotates the holding unit 110 by driving the motor 123, thereby inverting the support units 21 held by the holding unit 110.

  Note that the holding mechanism 100 is provided on the work floor so as to be movable along the longitudinal direction L of the support portion 21 in such a manner that the end portion of the support portion 21 is inserted or extracted when holding the support portion 21. It is preferable.

  The horizontal jack 200 is disposed between the support portions 21 of the temporary assembly provided side by side, and is disposed at the center portion in the longitudinal direction L. Then, by extending the horizontal jack 200, the central portion of each support portion 21 whose end is held by the holding mechanism 100 is separated, and bending is applied to each support portion 21. Instead of the horizontal jack 200, a gap holder may be sandwiched and installed between the two support portions 21. In short, the support portions 21 are connected to each other in a state where a gap is left in the center between the two support portions 21. to bound.

  Next, as shown in FIG. 7, the main welding 10 between the main body member 21 a and the plate member 21 b is performed on the two support portions 21 along the longitudinal direction L of the support portion 21 (main welding step). In this main welding process, a multi-electrode welding apparatus 300 is used.

  The multi-electrode welding apparatus 300 is one of the multi-electrode welding methods for the purpose of improving the efficiency of MAG welding, and includes a plurality of (two in this embodiment) welding torches, and adjacent support portions It travels along the welding part 21 and generates an arc at the same time. The multi-electrode welding apparatus 300 is arranged so as to be movable on a rail (not shown) along the longitudinal direction L, and can perform the main welding 10 continuously along the longitudinal direction L. That is, the main welding 10 is performed in synchronization with each support portion 21 along the longitudinal direction L by moving the multi-electrode welding apparatus 300 from the position shown in FIG. 6 to the position shown in FIG. The pair of welding torches is movable in the width direction orthogonal to the longitudinal direction L, and moves along the welding portion of each support portion 21 to perform welding.

  In this main welding step, after performing main welding 10 at a predetermined welding site along the longitudinal direction L of the support portion 21, as shown in FIG. 8, each support portion 21 is rotated by the holding mechanism 100, and FIG. Similarly, the main welding 10 of the other welding part along the longitudinal direction L of each support part 21 is performed. As shown in FIG. 4, the plate member 21b is fixed to the upper edge (predetermined welding part) and the lower edge (other welding part) of the opening part of the main body member 21a. Therefore, after performing the main welding 10 at the upper edge of the main body member 21a, it is necessary to reverse each support portion 21 up and down (rotate 180 degrees). Therefore, each support portion 21 is rotated by the rotation portion 120 of the holding mechanism 100.

  And after performing the main welding 10 of all the welding parts, the horizontal jack 200 is removed. For this reason, as shown in FIG. 9, each support portion 21 is linearly formed along the longitudinal direction L by bending opposite to the bending in the bending process due to distortion caused by thermal contraction of each support portion 21. . In this case, the holding portions 100 are not held by the holding mechanism 100 and are supported by the holding mechanism 100.

  By the way, in the above-described embodiment, the two temporarily assembled support portions 21 are arranged side by side so that the plate member 21b side is opposite to the support portion 21 in the opposite direction of the expected distortion due to the subsequent main welding 10. However, the present welding 10 is performed, but not limited to this.

  FIG. 10 is a schematic view showing another method for manufacturing a crane jib according to the present embodiment. As shown in FIG. 10, in the bending process, the two temporarily assembled support portions 21 are arranged side by side so that the plate member 21 b faces each other, and the support portion 21 is opposite to the expected strain due to the subsequent main welding 10. On the other hand, bending (reverse strain) may be applied. In this case, the center portion of each support portion 21 is restrained by the restraining jig 201, and the horizontal jacks 200 are disposed at both ends, and the end portions are held by the holding mechanism 100 by extending the horizontal jacks 200. The end portions of the support portions 21 are separated from each other, and bending is applied to the support portions 21. Although not clearly shown in the drawing, a gap holder may be sandwiched between the two support portions 21 in place of the horizontal jack 200 described above. In short, a gap is formed at both end portions between the two support portions 21, and the two support portions 21 are restrained in a state where there is no gap (or a state in which the spacer 12 is interposed) so that the center portions of the two support portions 21 are brought closer. In this case, the restraint at the center part of both support parts 21 is fixed by a restraining jig 201 provided at the center part of both support parts 21, or both plate members 21b are sandwiched and fixed by a jig (not shown). do it.

  The temporary assembly process and the main welding process are the same as described above.

  In FIG. 10, between the support portions 21 of the temporary assembly arranged side by side and disposed in the center portion in the longitudinal direction L is the spacer 12 and is a scratch caused by contact between the plate members 21b. This is to prevent sticking.

  Although the main body member 21a has been illustrated and described as a substantially U-shaped cross section, this is not restrictive. The main body member 21a is a long one formed by opening a side portion, and it is only necessary to reduce the weight and rigidity of the jib 2 by fixing the plate member 21b to the opening portion. For example, the main body member 21a may have a substantially U-shaped section or a C-shaped section. Further, the plate member 21b may not be a flat plate, and the cross-sectional shape may be curved or bent.

  As described above, in the crane jib manufacturing method of the present embodiment, the long main body member 21a formed by opening the side portion along the longitudinal direction L is long in the opening portion of the main body member 21a. It is a crane jib manufacturing method which forms the long hollow support part 21 which makes the crane jib 2 by welding the plate member 21b. Then, a temporary assembly step of temporarily welding the main body member 21 a and the plate member 21 b to temporarily assemble the support portion 21, and the two temporarily assembled support portions 21 are arranged side by side to oppose the expected distortion due to the main welding 10. The bending process which restrains the two support parts 21 mutually in the state which provided the bending in the direction, and the main welding process which performs the main welding of the two support parts 21 of the restrained state simultaneously are included. The main welding process includes performing the main welding 10 between the main body member 21 a and the plate member 21 b together on the two support portions 21 along the longitudinal direction of the support portion 21.

  According to this crane jib manufacturing method, in a state where the support portion 21 is temporarily assembled, the support portion 21 is previously bent in the direction opposite to the expected strain due to the main welding 10. It is possible to absorb the distortion sufficiently. Moreover, since the bending is applied to each support portion 21 while the two temporarily assembled support portions 21 are arranged side by side, the bending can be equally applied to the two support portions 21 forming the jib 2. Is possible. In addition, by performing the main welding 10 on the two support portions 21 by simultaneous construction, opposite strain stresses due to thermal shrinkage are equally generated on the two support portions 21, and for each one support portion 21. Compared with the case of welding, it becomes possible to make it far linear, and it is possible to minimize the occurrence of distortion of each support portion 21 that has been unconstrained. As a result, the crane jib can be easily manufactured.

  Moreover, the crane jib manufacturing method of this Embodiment rotates the support part 21 in the restrained state after a main welding process, and then performs the main welding of the other welding part of the two support parts 21 simultaneously. That is, in the main welding process, after performing the main welding 10 at a predetermined welding site along the longitudinal direction L of each support portion 21, the holding disposed in the work floor in a mode of holding the support portions 21 arranged side by side. Each of the support portions 21 is rotated by the mechanism 100, and the main welding 10 of another welding site is performed along the longitudinal direction L of each support portion 21.

  According to this crane jib manufacturing method, by rotating the support portion 21 while being constrained, it is possible to place another welded portion at a position where the main welding 10 can be easily performed. For this reason, the work of the main welding 10 can be easily performed. As a result, the crane jib can be easily manufactured. In addition, another holding part can be arrange | positioned in the position where main welding 10 is easy by rotating the support part 21 with the said holding mechanism 100, hold | maintaining each support part 21 with the holding mechanism 100. FIG. For this reason, the main welding operation can be easily performed. In addition, by applying the holding mechanism 100 that is installed on the work floor and holds the support portions 21, the main welding work can be easily performed without lifting the support portions 21 by lifting them with a crane or the like. is there. As a result, the crane jib can be easily manufactured.

  In the crane jib manufacturing method according to the above-described embodiment, the deck crane is described as an example of the crane having the jib 2, but the present invention is not limited to this, and the crane jib manufacturing method is applicable to all cranes having the jib 2 configured by the support portion 21. .

  As mentioned above, the crane jib manufacturing method which concerns on this invention is suitable for manufacturing a crane jib easily.

2 Crane jib (jib)
21 support part 21a body member 21b plate member 10 welding (main welding)
DESCRIPTION OF SYMBOLS 11 Temporary welding 12 Spacer 100 Holding mechanism 110 Holding part 120 Rotating part 121 Rotating mount 122 Driven gear 123 Motor 123a Drive gear 200 Horizontal jack 201 Restraint jig 300 Multi-electrode welding apparatus L Longitudinal direction of supporting part

Claims (2)

A long hollow support part that forms a crane jib is formed by welding a long plate member to the opening part of the main body member for a long main body member that is formed by opening the side part along the longitudinal direction. A crane jib manufacturing method,
A temporary assembling step of temporarily welding the support member by temporarily welding the main body member and the plate member;
A bending step of constraining the two support portions in a state where the two support portions temporarily assembled are arranged side by side, and bending is applied in a direction opposite to the expected strain due to the main welding;
A main welding process for simultaneously performing main welding of the two supporting portions in a restrained state;
Crane jib manufacturing method characterized by including.   2. The crane jib manufacturing according to claim 1, wherein after the main welding process, the support portion is rotated in a constrained state, and then the main welding of the other welding portions of the two support portions is simultaneously performed. Method.

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