JP2017081659A - Boom for work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boom for a work machine, which enables reduction in thickness of a steel plate forming a boom member, while preventing buckling of the boom member.SOLUTION: A boom member 41 is made up of a bent plate-like member and has a cross-sectional shape including protruding portions 50 each protruding inward of an outer peripheral portion. The protruding portion 50 has a pair of flat side-wall portions 51 each extending inward from the outer peripheral portion of the boom member 41, through a first bending portion 53. The flat side-wall portion 51 extends being bent inward at an angle within the range of 30 to 120 degrees relative to the outer peripheral portion of the boom member 41. This structure increases rigidity of the boom member 41 and improves strength against buckling, thus enabling reduction in thickness of the steel plate forming the boom member 41, and reduction in weight of the boom member 41.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a work machine boom applied to a work machine having a boom, such as a crane device.

  Conventionally, this kind of work machine boom is designed to reduce the weight of the boom member by reducing the thickness of the steel plate constituting the boom member. However, the boom for work machines has a problem in that, when the plate thickness is reduced, the rigidity of the boom member is reduced, so that it is likely to buckle when a large load is applied to the boom member.

  Therefore, as a structure of the boom member for suppressing buckling, the cross-sectional shape of the boom member is changed to a polygonal shape by bending the plate-like member and arranging the flat portion and the bent portion alternately, and the boom member has a rigid shape. There is known one that improves the above (for example, see Patent Document 1).

JP 2007-210715 A

  In the work machine boom, the rigidity of the boom member is improved by making the cross-sectional shape a polygonal shape. However, when the plate thickness of the steel plate constituting the boom member is further reduced, the rigidity of the boom member also decreases. Therefore, there is still a demand for improvement in strength against the buckling of the boom member.

  An object of the present invention is to provide a boom for a working machine capable of reducing the plate thickness of a steel plate constituting a boom member and suppressing buckling of the boom member.

  In order to achieve the above object, the present invention is a work machine boom including a boom member in which a plate-like member is formed in a cylindrical shape, and the boom member is bent at the outer peripheral portion by bending the plate-like member. The protrusion has a cross-sectional shape provided with a protrusion that protrudes inward or outward, and the protrusion has a pair of side wall flat portions extending inward or outward from the outer peripheral portion of the boom member via a bent portion. The flat portion is bent and extended inward or outward within an angle range of 30 to 120 degrees with respect to the outer peripheral portion of the boom member.

  Thereby, since the outer peripheral part of a boom member is reinforced by a protrusion part, the rigidity of a boom member is raised and buckling strength improves.

  According to the present invention, the rigidity of the boom member can be increased and the buckling strength can be improved. Therefore, the thickness of the steel plate constituting the boom member can be reduced, and the weight of the boom member can be reduced. It becomes possible.

It is a side view of the mobile crane which shows one Embodiment of this invention. It is a side view of a boom member. It is front sectional drawing of a boom member. It is principal part sectional drawing of a boom member. It is front sectional drawing which shows the accommodation with an adjacent boom member. It is front sectional drawing of the boom member which shows the example of another protrusion part. It is front sectional drawing of the boom member which shows the example of another protrusion part. It is front sectional drawing of the boom member which shows the example of another protrusion part.

  1 to 5 show an embodiment of the present invention.

  As shown in FIG. 1, a mobile crane 1 having a boom for a work machine according to the present invention has a lower traveling body 10 for traveling in a general road or a work area, and a horizontal direction with respect to the lower traveling body 10. And an upper revolving body 20 provided so as to be freely swivelable.

  The lower traveling body 10 includes wheels 11 provided on both sides in the width direction on the front side and the rear side of the carrier frame extending in the front-rear direction, outriggers 12 provided on both sides in the width direction on the front end portion and the rear end portion of the carrier frame, It has.

  The upper swing body 20 includes a swivel base 21 connected to the lower traveling body 10 via a swivel circle 30, a crane device 22 as a working device provided on one side in the width direction of the swivel base 21, and the width of the swivel base 21. A cab 23 that is provided on the other side in the direction and that operates the lower traveling body 10 and operates the crane device 22.

  The crane device 22 includes an extendable boom 40 that can be raised and lowered with respect to the swivel base 21.

  The telescopic boom 40 has a plurality of boom members 41 formed in a cylindrical shape, and the boom members 41 adjacent to the distal end side are housed inside the boom members 41 except for the most distal side. The telescopic boom 40 is configured such that the boom member 41 adjacent to the distal end side is movable with respect to the boom member 41 excluding the most advanced side, and is telescopic by a telescopic cylinder and a undulation cylinder driven by hydraulic oil discharged from a hydraulic pump. Perform movements and undulations.

  As shown in FIGS. 2 and 3, each boom member 41 is formed in a cylindrical shape having a pentagonal cross section by bending a steel plate by press working or the like. Each boom member 41 includes a top plate portion 41a constituting an upper portion, a pair of side plate portions 41b extending downward from both sides in the width direction of the top plate portion 41a, and a pair of side plate portions 41b as portions corresponding to the sides of the pentagon. And a pair of lower plate portions 41c extending obliquely downward from the lower end toward the center in the width direction.

  Protruding portions 50 that are formed by pressing or the like and project inward with respect to both sides in the width direction of the lower plate portion 41c are provided at the center portions in the width direction of the pair of lower plate portions 41c.

  The protruding portion 50 has a pair of side wall flat portions 51 extending from the lower plate portion 41 c to the inside of the boom member 41, and a connection flat portion 52 that connects the tips of the pair of side wall flat portions 51 to each other. Between the lower plate part 41c and each side wall flat part 51, the 1st bending part 53 is located. Moreover, the 2nd bending part 54 is located between each side wall flat part and a connection flat part.

  As shown in FIG. 4, the width dimension W <b> 1 of the connection flat part 52 is formed substantially the same as the width dimension W <b> 2 of the lower plate part 41 c on both sides of the protruding part 50.

  Each of the side wall flat portions 51 is bent and extends inward of the boom member 41 at a first angle θ1 with respect to the lower plate portion 41c. Further, the connection flat part 52 extends and bends at an angle of the second angle θ <b> 2 with respect to the side wall flat part 51. The first angle θ1 and the second angle θ2 are each at least 7 degrees or more, and preferably in the range of 30 degrees to 120 degrees.

  Further, the projecting dimension H with respect to the lower plate portion 41 c of the projecting portion 50 is at least twice the radius of curvature on the outer peripheral side of the first bent portion 53.

  In the telescopic boom 40 configured as described above, when a suspended load is suspended from the distal end of the boom member 41 on the most advanced side, a load acts on each boom member 41 in a direction in which the distal end side is displaced downward. At this time, a bending stress acts on each boom member 41.

  Each boom member 41 to which bending stress is applied is in a state in which tensile stress is applied on the upper side and is in a state in which compressive stress is applied on the lower side.

  In each boom member 41 of the present embodiment, the pair of lower plate portions 41c are portions where buckling is likely to occur due to the load of the suspended load. However, since the pair of lower plate portions 41c are reinforced by the protruding portions 50 and have increased rigidity, buckling due to the action of compressive stress is suppressed.

  Moreover, since the protrusion part 50 protrudes inside the boom member 41 and is engaged with the protrusion part 50 of the boom member 41 adjacent to the front end side as shown in FIG. 5, it is adjacent to the front end side. This is used as a guide when the matching boom member 41 moves.

  Thus, according to the boom for work machines of the present embodiment, the boom member 41 has a cross-sectional shape in which the protruding portion 50 that protrudes inward with respect to the outer peripheral portion is provided by bending the plate-like member. The protruding portion 50 has a pair of side wall flat portions 51 that extend inward from the outer peripheral portion of the boom member 41 via the first bent portion 53, and the side wall flat portion 51 is in relation to the outer peripheral portion of the boom member 41. It bends inward and extends within an angle range of 30 to 120 degrees.

  Accordingly, the rigidity of the boom member 41 can be increased and the buckling strength can be improved. Therefore, the thickness of the steel plate constituting the boom member 41 can be reduced, and the boom member 41 can be reduced in weight. It becomes possible.

  Further, the protrusion 50 has a connection flat part 52 that connects the tips of the pair of side wall flat parts 51 to each other.

  Accordingly, it is not necessary to bend the steel plate at a large angle that is difficult to bend, and the protruding portion 50 can be formed, so that the manufacturing cost can be reduced.

  Further, the protruding portion 50 is provided at the center of a pentagonal side provided on the outer peripheral portion of the boom member 41, and the width dimension W1 of the connecting flat portion 52 is the width dimension W2 on each side of the protruding portion 50 on the side. Is almost the same.

  Thereby, it becomes possible to raise rigidity over the whole lower board part 41c, and it becomes possible to suppress the buckling of the boom member 41 effectively.

  Further, the projecting dimension of the projecting part 50 with respect to the outer peripheral part of the boom member 41 is at least twice the radius of curvature of the first bent part 53.

  Thereby, it becomes possible to raise rigidity without deviation over the whole lower board part 41c, and it becomes possible to suppress buckling of the boom member 41 more effectively.

  Further, the protruding portion 50 is provided on the lower plate portion 41c on the outer peripheral portion of the boom member 41 where a compressive stress acts when a load is applied to the distal end portion of the boom member 41.

  As a result, it is possible to increase the rigidity of the portion where buckling is likely to occur when a load is applied to the boom member 41, and to effectively suppress the buckling of the boom member 41.

  In the above-described embodiment, the mobile crane is shown as the work machine having the boom. However, the present invention can be applied to a work machine such as an aerial work vehicle as long as the work machine has a boom.

  Moreover, in the said embodiment, when the load acted on the boom member 41, what applied this invention to the telescopic boom 40 of the crane apparatus 22 to which a compressive stress acts on the lower side of the boom member 41 was shown, but this It is not limited to. For example, when the present invention is applied to a boom of a digging pillar car, when a load is applied to the boom member, a compressive stress acts on the upper side of the boom member. What is necessary is just to form a part.

  Moreover, in the said embodiment, although what applied this invention to the telescopic boom 40 which has the several boom member 41 was shown, it is not restricted to this, Even if it is a boom which consists of one boom member, this The invention can be applied.

  Moreover, although the said embodiment showed what provided the protrusion part 50 which protrudes inside the boom member 41 from a pair of lower board part 41c of the boom member 41, it is not restricted to this. For example, as shown in FIG. 6, the same effect as that of the above embodiment can be obtained by providing a projecting portion 60 that projects from the pair of lower plate portions 41 c of the boom member 41 to the outside of the boom member 41. It becomes.

  Moreover, although the said embodiment showed what provided the protrusion part 50 in each of a pair of lower board part 41c of the boom member 41, it is not restricted to this. For example, as shown in FIG. 7, it is possible to simultaneously increase the rigidity of the pair of lower plate portions 41c by providing the protruding portion 70 at a position straddling the apex portion between the pair of lower plate portions 41c of the boom member 41. Thus, the same effect as in the above embodiment can be obtained.

  In the above-described embodiment, the protruding portion 50 is formed from the pair of side wall flat portions 51 and the connection flat portion connecting the tips of the pair of side wall flat portions 51. However, the present invention is not limited to this. is not. For example, as shown in FIG. 8, the protruding portion 80 may be formed of a pair of side wall flat portions 81 and a bent portion 82 that connects the tips of the pair of side wall flat portions 81 to each other. In this case, if the angle θ3 of the side wall flat part 81 with respect to the lower plate part 41c and the angle θ4 of the other side wall flat part 81 with respect to one side wall flat part 81 are within the range of 30 to 120 degrees, respectively, It is possible to obtain the same effect as the embodiment.

  DESCRIPTION OF SYMBOLS 40 ... Telescopic boom, 41 ... Boom member, 41c ... Lower board part, 50 ... Protrusion part, 51 ... Side wall flat part, 52 ... Connection flat part, 53 ... 1st bending part, 54 ... 2nd bending part, 60 ... Projection , 70 ... projecting part, 80 ... projecting part, 81 ... side wall flat part, 82 ... bent part.

Claims (7)

A boom for a working machine provided with a boom member in which a plate-like member is formed in a cylindrical shape,
The boom member has a cross-sectional shape provided with a protruding portion that protrudes inward or outward with respect to the outer peripheral portion by bending the plate-like member,
The protrusion has a pair of side wall flat portions extending inward or outward from the outer peripheral portion of the boom member via the bent portion,
The boom for a working machine, wherein the side wall flat portion is bent and extended inward or outward within an angle range of 30 degrees to 120 degrees with respect to an outer peripheral portion of the boom member. The boom for a working machine according to claim 1, wherein the protrusion has a bent portion that connects the tips of the pair of side wall flat portions to each other. The boom for a work machine according to claim 1, wherein the projecting portion has a connection flat portion that connects the tips of the pair of side wall flat portions to each other. The boom member has a polygonal cross section by bending the plate-like member,
The protrusion is provided at the center of the side of the polygon,
The boom for a work machine according to claim 3, wherein the width dimension of the connection flat portion is substantially the same as the width dimension of each side of the protruding portion on the side of the polygon. The boom member has a polygonal cross section by bending the plate-like member,
The boom for a working machine according to any one of claims 1 to 3, wherein the protruding portion is provided at a position straddling a vertex of the polygon. The boom for a working machine according to any one of claims 1 to 5, wherein a protruding dimension of the protruding portion with respect to the outer peripheral portion of the boom member is twice or more a radius of curvature of the bent portion. The protrusion is provided in a portion of the outer periphery of the boom member where a compressive stress acts when a load is applied to the tip of the boom member. The boom for work machines described.

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