JP5891716B2 - Attachment of work machine - Google Patents

Description

  The present invention relates to an attachment that can be undulated and attached to a base machine of a work machine.

  2. Description of the Related Art Conventionally, a work machine such as a demolition machine that performs a building demolition work is used with an ultralong attachment attached to a base machine.

  Such an attachment is generally a boom that can be raised and lowered to the base machine, a short inter boom that is pivotally attached to the tip of the boom, and a pivot that can be pivoted to the tip of the inter boom. With arm attached to.

  All of the boom, the inter boom, and the arm constituting the attachment have a rectangular closed cross section. For example, in the boom described in Patent Document 1, a rectangular closed cross section is constituted by a steel plate upper plate, a lower plate, and left and right side plates. The front end of the closed cross section is closed with an end closure plate. The end closing plate has an upper plate portion, a lower plate portion, and a curved portion that continuously connects the front end of the upper plate portion and the front end of the lower plate portion. The rear ends of the upper plate portion and the lower plate portion of the end closing plate are welded in a state of being in contact with the front ends of the upper plate and the lower plate on the upper surface and the lower surface of the boom, respectively. The end closing plate is bent so that the upper end portion and the lower end portion thereof are parallel to the upper plate and the lower plate, respectively, and is abutted and welded to the end portions of the upper plate and the lower plate.

JP 2006-28776 A

  However, in the case of the boom structure as described above, welded portions where the end closing plates are welded to the upper and lower plates are present on the upper and lower surfaces of the boom. A large bending stress, that is, a tensile stress or a compressive stress is generated on the upper surface and the lower surface of the boom due to the bending load in the undulation direction that the boom receives during operation of the work machine. Therefore, the welded portions present on the upper surface and the lower surface of the boom tend to have relatively low bending strength and fatigue strength compared to the welded portions at other locations, and as a result, improve the fatigue life of the boom. It has become difficult.

  The present invention has been made in order to solve the above-described problem, and is a work machine capable of suppressing a decrease in fatigue strength of a joint portion of an upper plate and a lower plate of an attachment and improving a fatigue life of the entire attachment. An attachment is provided.

Working machine attachment of the present invention, there is provided a attachment mounted freely undulating work machine base machine, the upper plate, lower plate, and the left and right sides and configured closed cross section by the side plates, the closed cross section A shielding plate for closing a part of the open portion at the end in the longitudinal direction; and a pair of side walls provided so as to protrude forward or rearward of the closed cross-section along the side plates on both sides. The upper plate and / or the lower plate has a shielding part bent in a direction to close the opening part of at least one of its end parts, and the opening part is formed by the shielding plate and the shielding part. The shield plate and the shield part are joined at a position deviating from the upper surface or the lower surface of the closed cross-section at the tip of the shield part, and the joint part between the shield plate and the shield part is the pair. Side wall Is disposed, said both side ends of the shielding plate and the shielding portion, they are respectively bonded to the mutually opposing inner surfaces of the pair of side walls, characterized in that.

  An object of the present invention is to eliminate an excessive burden on the joint when stress occurs in the attachment, and the upper and lower surfaces of the attachment that have the greatest bending stress at the joint that is the most disadvantageous in strength. By setting the position retracted to the inside, damage at the joint is avoided.

That is, in the attachment of the present invention, the closed cross section is constituted by the upper plate, the lower plate, and the left and right side plates, and the upper plate and / or the lower plate has a lengthwise direction of at least one closed cross section at the end thereof. It has a shielding part bent in a direction to close the open part of the end part. The open portion is shielded by the shielding plate and the shielding portion, and the shielding plate and the shielding portion are joined at a position away from the upper surface or the lower surface of the closed cross-sectional portion at the tip of the shielding portion. As a result, when the attachment receives a bending load from the outside, a large bending stress is generated in the portion constituting the closed cross-sectional portion continuously extending in the longitudinal direction of the upper and lower plates constituting the upper and lower surfaces of the attachment. Even if it occurs, the bending stress generated at the joint between the upper plate and the lower plate at a position retracted from the upper and lower surfaces of the attachment is relatively smaller than the bending stress generated at the upper and lower surfaces of the attachment. For this reason, it is possible to suppress a decrease in bending strength and fatigue strength of the joint portion, and it is possible to improve the fatigue life of the entire attachment.
Further, the joint portion between the shielding plate and the shielding portion is disposed between the pair of side walls, and both side ends of the shielding plate and the shielding portion are joined to the inner surfaces of the pair of sidewalls facing each other, The shielding plate and the shielding portion are fixed by a pair of side walls at the periphery of these joint portions. As a result, it is possible to reduce the risk of damage at the joint portion.

  The shielding portion of the upper plate or the lower plate is preferably bent so as to be inclined at an angle larger than 90 degrees and smaller than 180 degrees.

  According to such a configuration, the shielding portion of the upper plate or the lower plate is bent so as to have an angle larger than 90 degrees and smaller than 180 degrees, that is, an obtuse angle. It is possible to alleviate the stress concentration on the top.

  The shielding portion of the upper plate bends in a direction to close the open portion of the closed cross section, and is joined to the shielding plate at a position deviating from the upper surface of the closed cross section at the tip of the shielding portion. Is preferred.

  In many cases, the attachment is tilted forward and tilted forward during work. In this case, the highest bending stress is generated on the upper surface of the attachment. In order to retract the joint portion, the shielding portion of the upper plate bends in a direction to close the open portion of the closed cross-sectional portion, and the shielding plate (for example, at a position deviated from the upper surface of the closed cross-sectional portion at the tip of the shielding portion) , The front plate or the rear plate). Therefore, even if a large bending stress occurs in the portion constituting the closed cross-sectional portion that continuously extends in the longitudinal direction, the upper plate that is in the position retracted from the upper surface of the attachment. The bending stress generated at the joint portion is relatively smaller than the bending stress generated at the upper surface of the attachment. For this reason, it is possible to suppress a decrease in bending strength and fatigue strength of the joint portion, and it is possible to improve the fatigue life of the entire attachment.

  The shielding portion on the front side of the upper plate is bent in a direction to close the opening portion of the closed cross section, and is joined to the shielding plate at a position away from the upper surface of the closed cross section at the tip of the shielding portion. It is preferable.

  In this configuration, the joint between the shield part on the front side of the upper plate of the attachment and the shield plate is a joint between the boards, so it is difficult to improve the joint strength, but a large bending stress is generated in this part. In order to avoid this, the joint portion is retracted inward of the attachment. Specifically, the shielding portion on the front side of the upper plate bends in a direction to close the opening portion of the closed cross section, and is joined to the shielding plate at a position away from the upper surface of the closed cross section at the tip of the shielding portion. ing. Therefore, even if a large bending stress occurs in the portion constituting the closed cross-sectional portion that continuously extends in the longitudinal direction, the upper plate that is in the position retracted from the upper surface of the attachment. The bending stress generated at the joint portion is relatively smaller than the bending stress generated at the upper surface of the attachment. For this reason, it is possible to suppress a decrease in bending strength and fatigue strength of the joint portion, and it is possible to improve the fatigue life of the entire attachment.

  Preferably, the upper plate, the lower plate, the left and right side plates, and the shielding plate constitute a boom that is attached to the base machine so as to be raised and lowered.

  Since the boom is attached to the base machine so that it can be raised and lowered, it receives the driving force from the base machine and the weight of an arm or the like provided on the tip side of the boom. For this reason, the boom generates the largest bending stress among the attachments. Therefore, at a position where the shielding portion of the upper plate or the lower plate constituting such a boom bends in a direction to close the open portion of the closed cross section, and deviates from the upper surface or the lower surface of the closed cross section at the tip of the shield portion. It is joined to a shielding plate (for example, a front plate or a rear plate). Therefore, even if a large bending stress is generated in the portion constituting the closed cross-section portion in which the upper plate and the lower plate constituting the upper surface and the lower surface of the boom continuously extend in the longitudinal direction, the upper plate and the lower plate The joint is retracted from the upper and lower surfaces of the boom to the inside of the boom, and the bending stress generated at the inner position of the boom is relatively smaller than the bending stress generated at the upper and lower surfaces of the boom. . Therefore, it is possible to suppress a decrease in the bending strength and fatigue strength of the joint portion, and the fatigue life of the entire boom can be improved.

The boom has a plurality of boom bodies that can be detachably connected to each other along the longitudinal direction of the boom, and each boom body includes the upper plate, the lower plate, and the left and right sides. and side plates of said shielding plate, the closure cross section and the projecting forwardly, has a pair of side walls having a front of the other boom member connectable shape, each of the boom body, The shield part on the front side of the upper plate of the boom body bends in a direction to close the open part of the closed cross section, and the shield part is at a position away from the upper surface of the closed cross section at the tip of the shield part. It is preferable that both side ends of the shielding portion on the front side of the upper plate and both side ends of the shielding plate are joined to the side wall, respectively.

  According to such a configuration, when the boom is a split-type boom having a plurality of boom bodies, the shielding portion on the front side of the upper plate constituting the upper surface of the boom body in each boom body is the opening of the closed cross section. It bends in the direction which closes a part, and is joined to a shielding board in the position which remove | deviated from the upper surface of the said closed cross-section part in the front-end | tip of the said shielding part. Therefore, even if a large bending stress is generated in the portion constituting the closed cross-section portion in which the upper plate constituting the upper surface of the boom body extends continuously in the longitudinal direction, the upper plate constituting the upper surface of the boom body is in a position retracted from the upper surface of the boom body. The bending stress generated at the joint portion of the upper plate is relatively smaller than the bending stress generated at the upper surface of the boom body. Therefore, it is possible to suppress a decrease in the bending strength and fatigue strength of the joint portion, and the fatigue life of each boom body and the entire boom can be improved.

  In addition, the joint position between the upper plate and the shielding plate of each boom body is located between the pair of side walls, and both side ends of the shielding portion on the front side of the upper plate and both side ends of the shielding plate are joined to the side walls. Therefore, since the upper plate and the shielding plate are fixed by the pair of side walls at the periphery of the joining position between the upper plate and the shielding plate, it is possible to reduce the risk of damage at the joining position.

  According to the present invention, it is possible to suppress a decrease in the bending strength and fatigue strength of the joint portion between the upper plate and the lower plate of the attachment, and the fatigue life of the entire attachment can be improved.

It is a schematic side view of the state which extended and started up the attachment of the dismantling machine with a super-long attachment concerning the embodiment of the present invention. It is a schematic side view of the state which folded the attachment of the demolition machine of FIG. It is a perspective view of the insert boom of the attachment of FIG. It is a front view of the insert boom of the attachment of FIG. It is a top view of the insert boom of FIG. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. It is an enlarged view of the overhang | projection part of FIG. FIG. 3 is a cross-sectional view showing a state before connecting the insert booms in a folded state of the attachment of FIG. 2. FIG. 3 is a plan view showing a state before the insert booms are connected to each other in the folded state of the attachment of FIG. 2. It is a bottom view which shows the state before connecting insert booms in the state which the attachment of FIG. 2 was folded. It is sectional drawing which shows the state after connecting the insert booms of FIG. It is a top view which shows the state after connecting the insert booms of FIG. It is a bottom view which shows the state after connecting the insert booms of FIG. It is a front view of the main boom of the attachment of FIG. It is a longitudinal cross-sectional view of the main boom of FIG. It is a perspective view of the main boom of FIG.

  In the following embodiments, the dismantling machine 1 with an ultralong attachment is applied as an embodiment of a working machine provided with the attachment of the present invention in accordance with the description of the background art.

  The demolition machine 1 of this embodiment is comprised from the base machine 2 and the work attachment 3, as FIG. The base machine 2 includes a crawler-type lower traveling body 4 and an upper revolving body 5 that is mounted on the lower traveling body 4 so as to be rotatable about a vertical axis. The work attachment 3 is attached to the front part of the base machine 2.

  The work attachment 3 includes a boom 6 attached to the base machine 2 (upper turning body 5) so as to be able to move up and down, and a short inter boom attached to the tip of the boom 6 so as to be rotatable about a horizontal axis in the vertical direction. 7, an arm 8 whose rear end portion is attached to the front end of the inter boom 7 so as to be pivotable in the vertical direction around a horizontal axis, and a crushing device 9 such as a nibler attached to the front end portion of the arm 8. It is equipped with.

  The boom 6 includes a plurality of boom bodies, that is, a main boom 6a, a front boom 6b, and insert booms 6c1 and 6c2. The main boom 6 a constitutes a portion on the base side of the boom 6, and is attached to the upper swing body 5 so as to be raised and lowered. The front boom 6b constitutes a portion on the tip side of the boom 6, and the inter boom 7 is rotatably attached to the tip portion.

  The insert booms 6c1 and 6c2 are interposed between the main boom 6a and the front boom 6b, and the length of the boom 6 can be extended to a length suitable for the dismantling work. The insert boom 6c1 is connected to the root side end of the front boom 6b, the insert boom 6c2 is connected to the root side end of the insert boom 6c1, and the root end of the insert boom 6c2 is further connected to the root side end. The main boom 6a is connected.

  1-2, as a cylinder for operating the work attachment 3, a boom cylinder 10 for raising and lowering the boom 6 (the entire attachment 3), an inter boom cylinder 11 for operating the inter boom 7, and an arm 8 are operated. An arm cylinder 12 is provided, and a crushing device cylinder 13 for rotating the crushing device 9 about a horizontal axis is provided.

  As shown in FIG. 2, when the work attachment 3 is folded and transported, the attachment 3 is folded in a three-fold state with the front boom 6b on the upper side and the arm 8 on the lower side with the inter boom 7 as a boundary. In other words, the base machine 2 and the main boom 6a are assembled, the work boom 3a excluding the main boom 6a and the insert boom 6c2, and the insert boom 6c2 are separated and transported. After transportation, they are assembled in the same state.

  In this work attachment 3, the insert boom 6c2 is separated from the insert boom 6c1 after being folded in a three-fold state as shown in FIG. 2, and then separated from the main boom 6a. When assembling, they are connected in the reverse order.

(Configuration of insert boom 6c2)
Here, the configuration of the insert boom 6c2 will be specifically described as an example of a plurality of boom bodies constituting the boom 6. The insert booms 6c1 and 6c2 correspond to the boom bodies of the present invention, respectively. Furthermore, since the insert booms 6c1 and 6c2 have the same configuration as described below, the description of the configuration of the insert boom 6c1 is omitted in this embodiment.

  As shown in FIGS. 3 to 5, the insert boom 6 c 2 includes a main body 20, a pair of front side walls 22, a pair of rear side walls 23, a fixing pin 24, and a pin support portion 25.

<Front side wall 22>
The pair of front side walls 22 are respectively arranged so as to protrude forward of the main body 20 along side plates 21c and 21d on both sides of a closed cross section 21 of the main body 20 described later. The front side wall 22 corresponds to the side wall of the present invention.

  The front side wall 22 has a hook portion 30 and a pin attachment portion 31 as two engaging portions that can be detachably engaged with the rear end portion of the insert boom 6c1 provided on the front end side of the insert boom 6c2. .

  6-7, the hook part 30 has the notch 32 which can be engaged with the fixing pin 24 of the rear-end part of the insert boom 6c1. The hook portion 30 is disposed closer to the front end 22a in the protruding direction A of the front side wall 22 and closer to the upper plate 21a than the pin mounting portion 31 is. The opening 32 a of the notch 32 opens toward the front upper side of the front side wall 22. In the front side wall 22 of this embodiment, the periphery of the notch 32 is reinforced by partially overlapping steel plates.

  The pin attachment portion 31 has a pin hole 33 formed through the side wall 22. The pin hole 33 is disposed in the direction C from the opening 32 a in the notch 32 toward the back end 32 b with respect to the hook portion 30.

<Main body 20>
The main body 20 includes a closed cross-sectional portion 21, a protruding portion 26 on the front side of the closed cross-sectional portion 21, and a recessed portion 27 on the rear side of the closed cross-sectional portion 21. The overhang portion 26 is disposed at the front end of the closed cross section 21 and has a front plate 35. The front plate 35 corresponds to the shielding plate of the present invention.

  The closed cross-sectional portion 21 is a long casing having a rectangular cross-sectional shape, which includes an upper plate 21a, a lower plate 21b, and left and right side plates 21c and 21d. The upper plate 21a and the lower plate 21b are spaced apart from each other in the vertical direction, and both side ends of the upper plate 21a and the lower plate 21b are welded to the side plates 21c and 21d on both sides.

  A part of the opening portion of the end portion in the longitudinal direction of the closed cross-sectional portion 21 (that is, the front ends 21c1 and 21d1 of the side plates 21c and 21d) is shielded by the front plate 35, and the other portions are shielded forward of the upper plate 21a1. It is shielded by the portion 21a1. The open portion is an opening portion opened in the longitudinal direction formed by the upper plate 21a, the lower plate 21b, and the left and right side plates 21c, 21d at the front ends 21c1, 21d1.

  As shown in FIG. 6, the upper plate 21 a includes an upper surface constituent portion 40 that continuously extends in the longitudinal direction of the insert boom 6 c 2 constituting the upper surface of the insert boom 6 c 2, and an insert boom from the front end of the upper surface constituent portion 40. 6c2 and a bent portion 39 bent inward.

  Further, when viewed from the relationship with the closed cross-section portion 21, the upper plate 21 a extends continuously in the longitudinal direction, and an intermediate portion 21 a 3 constituting the closed cross-section portion 21 and the front of the closed cross-section portion 21 in the longitudinal direction. A front shielding portion 21a1 extending forward in the longitudinal direction from the side end portion (that is, the front ends 21c1, 21d1 of the side plates 21c, 21d), and an end portion on the rear side in the longitudinal direction of the closed cross-sectional portion 21 (that is, The rear ends 21c2 and 21d2) of the side plates 21c and 21d are formed from a rear extension 21a2 extending rearward in the longitudinal direction. These intermediate part 21a3, front shielding part 21a1, and rear extension part 21a2 are continuous in the longitudinal direction.

  The bent portion 39 is formed on the front side of the front shielding portion 21a1 of the upper plate 21a. The front shielding portion 21a1 corresponds to the shielding portion of the present invention. Specifically, the front shielding portion 21a1 is a portion that extends forward from the front ends 21c1 and 21d1 of the side plates 21c and 21d so as to be continuous with the intermediate portion 21a3 that constitutes the upper surface of the closed cross section 21 of the upper plate 21a. is there.

  6-7, the bending part 39 formed in the front side of the front shielding part 21a1 is a position away from the front end 37 of the front shielding part 21a1 by a predetermined distance X (that is, the bending top part). 38), it is bent in a direction to close the open portion of the closed cross section 21. In other words, the bent portion 39 is retracted inward from the outer peripheral surface of the closed cross section 21, that is, toward the inner side of the insert boom 6 c 2 (specifically, approaches the lower plate 21 b toward the front. It is a bent part.

  As shown in FIG. 7, the front shielding portion 21 a 1 bends in a direction to close the opening portion of the closed cross-section portion 21, and at the position deviated from the upper surface of the closed cross-section portion 21 at the tip of the shielding portion 21 a 1. It is joined to. In other words, the front shielding portion 21a1 is retracted from the upper surface of the insert boom 6c2 in the bent portion 39, specifically, in front of the bent top portion 38 and between the pair of front side walls 22. At the joining position 36 at the tip of the shielding part 21a1, the upper end part 35a of the front plate 35 is joined by welding. Thereby, the joining position 36 of the upper plate 21a is retracted from the upper surface constituting portion 40 constituting the upper surface of the insert boom 6c2 to the inside of the insert boom 6c2.

  In the present embodiment, the front end 37 of the front shielding portion 21a1 of the upper plate 21a and the upper end 35a of the front plate 35 are abutted, and the backing metal 41 is applied to the abutted portion from the inside of the overhang portion 26. The front shielding portion 21a1 and the front plate 35 are butt welded.

  Further, the front shielding portion 21a1 of the upper plate 21a has an angle (so-called obtuse angle) larger than 90 degrees and smaller than 180 degrees with respect to the upper surface constituent portion 40 in which the upper plate 21a continuously extends in the longitudinal direction. It is bent so as to be inclined at an inclination angle θ1.

  The distance X from the front end 37 of the front shielding portion 21a1 to the bending top portion 38 and the inclination angle θ1 of the bending portion 39 are appropriately set based on conditions such as the dimensions of the overhang portion 26.

  The front and rear sides of the left and right side plates 21c and 21d are inclined forward as they go from the lower plate 21b to the upper plate 21a.

  The overhang portion 26 protrudes forward on the front side of the closed cross-section 21 so as to continue from the upper plate 21 a to the lower plate 21 b between the pair of front side walls 22.

  Side ends 26b (see FIG. 5) on both sides of the overhang portion 26 are joined to the pair of front side walls 22 by welding.

  The overhang portion 26 includes a front plate 35 bent so as to protrude forward, a front shielding portion 21a1 of the upper plate 21a, a cylindrical portion 25a of the pin support portion 25, and a front extension portion 21b1 of the lower plate 21b. .

  The front extension portion 21b1 of the lower plate 21b is a portion obtained by extending the front end portion of the lower plate 21b forward from the front ends of the side plates 21c and 21d. The front end portion of the front extension portion 21b1 is welded to the cylindrical portion 25a. The lower end of the front plate 35 is also welded to the cylindrical portion 25a.

  In the overhang portion 26 of the present embodiment, as shown in FIG. 7, the tip 26 a in the protruding direction A of the overhang portion 26 is a straight line connecting the center O 1 of the hook portion 30 of the front side wall 22 and the center O 2 of the pin attachment portion 31. It is located forward in the projecting direction A from L. Here, the center O 1 of the hook portion 30 is the center of curvature of the back end face of the notch 32, and the center O 2 of the pin mounting portion 31 is the center of the pin hole 33.

  The tip 26 a in the protruding direction A of the overhang portion 26 is disposed at a position closer to the notch 32 of the hook portion 30 than the pin hole 33 of the pin mounting portion 31.

  As shown in FIGS. 4 to 5, the recessed portion 27 is recessed forward of the insert boom 6c1 at the rear end of the insert boom 6c1, and the projecting portion 56 of the main boom 6a connected to the rear end of the insert boom 6c1. (See FIGS. 14 to 16) is a portion that can be accommodated.

  Side ends 27b (see FIG. 5) on both sides of the recessed portion 27 are joined to the pair of rear side walls 23 by welding.

  The recessed portion 27 is recessed forward from the rear end portion at the rear end portion of the closed cross section 21. The recessed portion 27 includes a rear plate 37 bent so as to protrude forward, a rear extension portion 21a2 of the upper plate 21a, a rear extension portion 21b2 of the lower plate 21b, an upper cylinder 28, and a lower cylinder 29. . The rear extension portion 21a2 of the upper plate 21a is a portion in which the rear end portion of the upper plate 21a extends rearward from the rear ends of the side plates 21c and 21d, and the rear extension portion 21b2 of the lower plate 21b is the rear extension portion of the lower plate 21ba. It is the part which extended the edge part back rather than the rear end of the side plates 21c and 21d. The upper cylinder 28 extends in the width direction of the insert boom 6c2 (the direction perpendicular to the plane of FIG. 4 and FIG. 6), and is welded to the rear extension portion 21a2 of the upper plate 21a and the rear plate 37, respectively. The lower cylinder 29 extends in the width direction of the insert boom 6c2 (the direction perpendicular to the plane of FIG. 4 and FIG. 6) and is welded to the rear extension 21b2 and the rear plate 37 of the lower plate 21b.

  In the main body 20 of the present embodiment, the range having the left and right side plates 21c and 21d constitutes a closed cross-sectional portion 21 having a rectangular cross-sectional shape, and the portion protruding forward from the side plates 21c and 21d constitutes an overhang portion 26. Furthermore, the part which protruded back rather than the side plates 21c and 21d comprises the recessed part 27. FIG.

<Back side wall 23>
4-6, a pair of back side wall 23 is each provided so that it may protrude in the back of the main body 20 along the side plate 21c21d of the both sides of the closed cross-section part 21. As shown in FIG.

  The rear side wall 23 is connected to the hook portion 30 and the pin attachment portion 31 (see FIGS. 14 to 16) of the main boom 6a connected to the rear end side of the insert boom 6c2.

  A pin hole 23 a is formed at a position above the rear end of the rear side wall 23. Both end portions of the fixing pin 24 can be fitted into the pin holes 23a of the pair of rear side walls 23, respectively.

  Further, a rear projecting portion 23b projecting rearward is formed below the rear end of the rear side wall 23. A pin hole 23c is formed near the tip of the rearward projecting portion 23b. The pin hole 23c has substantially the same diameter as the pin hole 33 (see FIGS. 14 to 16) of the pin mounting portion 31 of the front side wall 22 of the main boom 6a connected to the rear end side of the insert boom 6c2.

  When connecting the insert boom 6c2 and the main boom 6a, the pin hole 23c on the rear side wall 23 on the insert boom 6c2 side and the pin hole 33 on the front side wall 22 on the main boom 6a side are overlapped, and these pin holes 23c and 33 are overlapped. The pin 50 (see FIGS. 11 to 13) is inserted so as to pass through the pin hole 23c and the pin holes 23c and 33 are engaged. As the pins 50, for example, two short pins are used for each of the pair of rear side walls 23 on the insert boom 6c2 side so that an operator can easily insert and remove the pins.

<Fixing pin 24>
As shown in FIGS. 4 to 6, the fixing pin 24 extends in the width direction W (see FIG. 5) of the upper plate 21 a, and both ends thereof are fitted in the pin holes 23 a at the rear end of the rear side wall 23. doing. The fixing pin 24 is engaged with the notch 32 of the hook portion 30 of the front side wall 22 of the main boom 6a connected to the rear end side of the insert boom 6c2.

  The fixing pin 24 is not only a relatively long pin fixed at both ends by a pair of pin holes 23a as in the present embodiment, but also a pair of short fixing pins directed inward from the pair of pin holes 23a. It may be provided so as to protrude.

<Pin support part 25>
4-6, the pin support part 25 is inserted in the pin hole 33c of a pair of back side wall 23 of the insert boom 6c1 and the pin hole 33 of a pair of front side wall 22 of the insert boom 6c2, and its front end side. A short pin 50 (see FIGS. 11 to 13) is supported from the outside. The pin support portion 25 has a cylindrical portion 25a and a pair of connecting plates 25b.

  The cylindrical portion 25 a is provided through the pair of front side walls 22. The cylindrical portion 25a is welded to the front plate 35 and the front extension portion 21b1 of the lower plate 21b between the pair of front side walls 22, respectively. Furthermore, the cylindrical portion 25a and the front side wall 22 are welded around the portion of the front side wall 22 through which the cylindrical portion 25a passes.

  The pair of connecting plates 25b is made of an elongated plate-like member. The rear side ends of the connecting plate 25b are welded to both ends of the cylindrical portion 25a so that a gap 34 is formed between the connecting plate 25b and the front side wall 22. In the gap 34, a rear protruding portion 23b (see FIGS. 8 to 9) of the rear side wall 23 of the insert boom 6c1 connected to the distal end side of the insert boom 6c2 can be inserted.

  A pin hole 25b1 is formed at the front end of the connecting plate 25b. The pin hole 25b1 has substantially the same diameter as the pin hole 33 on the front side wall 22 facing the connecting plate 25b, and is aligned on the same axis as the pin hole 33.

(Configuration of main boom 6a)
The main boom 6a shown in FIGS. 14 to 16 includes a pair of front side walls 22, a pin support portion 25, a main body 51 having an overhanging portion 56, an upper swing body connecting cylinder 52, and a cylinder connecting cylinder 53. Yes.

  As described above, the main boom 6a is common to the insert boom 6c2 in that it includes the front portion of the insert boom 6c2, that is, the pair of the front side wall 22 and the pin support portion 25. Is omitted.

  The main body 51 of the main boom 6 a has a closed cross section 54 and an overhanging portion 56 on the front side of the closed cross section 54. The overhang portion 56 is disposed at the front end of the closed cross section 54 and has a front plate 55. The front plate 55 corresponds to the shielding plate of the present invention.

  The closed cross section 54 has an upper plate 54a, a lower plate 54b, and a pair of side plates 54c and 54d. The side plates 54c and 54d are sandwiched from above and below between the upper plate 54a and the lower plate 54b. The upper and lower ends of the side plates 54c and 54d are welded to the upper plate 54a and the lower plate 54b. The lower plate 54b is inclined upward as it goes to the rear side. The rear side ends of the upper plate 54 a and the lower plate 54 b are connected to the upper swing body connecting cylinder 52.

  A part of the opening portion of the end portion in the longitudinal direction of the closed cross-sectional portion 54 (that is, the front ends 54c1 and 54d1 of the side plates 54c and 54d) is shielded by the front plate 55, and the other portion is shielded forward of the upper plate 54a1. It is shielded by the portion 54a1. The open portion is an opening portion opened in the longitudinal direction formed by the upper plate 54a, the lower plate 54b, and the left and right side plates 54c, 54d at the front ends 54c1, 54d1.

  As shown in FIG. 15, the upper plate 54 a includes an upper surface constituent portion 62 that continuously extends in the longitudinal direction of the main boom 6 a constituting the upper surface of the main boom 6 a, and a main boom from the front end of the upper surface constituent portion 62. 6a, and a bent portion 61 bent inward.

  The bent portion 61 is formed on the front side of the front shielding portion 54a1 of the upper plate 54a. Specifically, the front shielding portion 54a1 is a portion that extends forward from the front ends 54c1 and 54d1 of the side plates 54c and 54d so as to be continuous with the intermediate portion 54a2 that constitutes the upper surface of the closed cross section 54 of the upper plate 54a. is there. The front shielding portion 54a1 corresponds to the shielding portion of the present invention.

  As shown in FIGS. 14 to 15, the bent portion 61 formed on the front side of the front shielding portion 54a1 is located rearward from the front end 57 of the front shielding portion 54a1 by a predetermined distance Y (that is, the bending top portion). 58), it is bent in a direction to close the open portion of the closed cross section 54. In other words, the bent portion 61 is a portion bent toward the inside of the main boom 6a (specifically, toward the lower plate 54b as it goes forward).

  As shown in FIGS. 15 to 16, the front shielding portion 54 a 1 bends in a direction to close the open portion of the closed cross-sectional portion 54, and the front shield portion 54 a 1 moves forward from the top surface of the closed cross-sectional portion 54 at the tip of the shield portion 54 a 1. It is joined to the plate 55. In other words, the front shielding portion 54a1 is retracted from the upper surface of the main boom 6a in the bent portion 61, specifically, in front of the bent top portion 58 and between the pair of front side walls 22. In the position 59, it joins with the upper end part 60 of the front board 55 by welding. Thereby, the joining position 59 of the upper plate 54a is retracted inward of the main boom 6a from the upper surface component 62 constituting the upper surface of the main boom 6a.

  Further, the front shielding portion 54a1 of the upper plate 54a has a bent portion 61 that is larger than 90 degrees and larger than 180 degrees with respect to the upper surface constituting portion 62 in which the upper plate 54a extends from the rear end to the bent top portion 58. It is bent so as to incline at an inclination angle θ2 of a small angle (so-called obtuse angle).

  Similar to the distance X and the inclination angle θ1 in the insert boom 6c2 described above, the distance Y from the front end 57 of the front shielding part 54a1 to the bending top part 58 and the inclination angle θ2 of the bending part 61 are It is set as appropriate based on conditions such as dimensions.

  Similar to the overhang portion 26 of the insert boom 6c2, the overhang portion 56 includes a front plate 55 bent so as to protrude forward, a front shielding portion 54a1 of the upper plate 54a, and a cylindrical portion 25a of the pin support portion 25. And a front shielding portion 54b1 of the lower plate 54ab.

  The upper swing body connecting cylinder 52 is rotatably supported by a horizontal shaft attached to the upper swing body 5 of the base machine 2 shown in FIGS. Thereby, the main boom 6a is attached to the upper revolving body 5 so that it can be raised and lowered.

  The cylinder coupling cylinder 53 is coupled to a rod tip portion of the boom cylinder 10 shown in FIGS.

(Configuration of front boom 6b)
The inter boom 7 is connected around the rotation axis around the horizontal axis on the front end side of the front boom 6b shown in FIGS. Moreover, the front-end | tip part of the insert boom 6c1 is connected to the rear end side of the front boom 6b.

  The rear portion of the front boom 6b has the same configuration as the rear portion of the insert boom 6c2, that is, a pair of the rear side wall 23, the recessed portion 27, and the fixing pin 24.

  In addition, also in the arm 8 and the inter boom 7 of this embodiment, similarly to the insert boom 6c2 and the main boom 6a, a long closed cross section having a rectangular cross section having an upper plate, a lower plate, and left and right side plates. Has a part.

(Explanation of the method of connecting the insert booms 6c1 and 6c2)
Next, a method for connecting the insert booms 6c1 and 6c2 will be described with reference to FIGS.

  Before connecting the insert booms 6c1 and 6c2, as shown in FIGS. 8 to 10, the rear end portion of the insert boom 6c1 faces the front end portion of the insert boom 6c2. Specifically, as shown in FIG. 2, a set of work attachments 3a excluding the main boom 6a and the insert boom 6c2 in the work attachment 3 is installed on the ground in a state of being folded in three, and the main boom 6a The insert boom 6c2 connected in advance to the tip end of the insert boom 6c2 is moved to align the tip end portion of the insert boom 6c2 with the rear end portion of the insert boom 6c1.

  Next, as shown in FIGS. 11 to 13, by driving the base machine 2, the insert boom 6 c 2 is advanced and connected to the rear end portion of the insert boom 6 c 1.

  Specifically, first, the notch 32 of the hook portion 30 which is on the distal end side in the protruding direction of the front side wall 22 of the insert boom 6c2 and closer to the upper plate 21a than the pin hole 33 of the pin mounting portion 31 is provided. The insert boom 6c1 is engaged with the fixing pin 24 at the rear end portion.

  At this time, as shown in FIGS. 12 to 13, the rear protruding portion 23 b of the rear side wall 23 on the insert boom 6 c 1 side is inserted into the gap 34 between the connecting plate 25 b on the insert boom 6 c 2 side and the front side wall 22. Thereby, the pin hole 23c of the rear side wall 23 on the insert boom 6c1 side communicates with the pin hole 33 on the front side wall 22 on the insert boom 6c2 side and the pin hole 25b1 of the connecting plate 25b in a coaxial manner.

  At the same time, as shown in FIG. 11, the overhanging portion 26 protruding forward of the closed cross-section 21 on the insert boom 6c2 side enters the inside of the recessed portion 27 recessed forward from the rear end portion of the insert boom 6c1. .

  Thereafter, the operator passes a pair of short pins 50 through all of the pin holes 25b1, 23c and 33 from both sides of the insert boom 6c2, and the front side wall 22 on the insert boom 6c2 side and the rear side wall 23 on the insert boom 6c1 side. And engage. Thus, the insert booms 6c1 and 6c2 are engaged with the fixing pin 24 and the notch 32 on the upper side of the front side wall 22, and on the lower side, the front side wall 22 and the rear side wall 23 formed by the pin 50 are engaged. As a result of the coupling, the connection of the insert booms 6c1 and 6c2 is completed.

  Further, similarly to the connection between the insert booms 6c1 and 6c2, the connection between the other boom bodies, for example, the connection between the front boom 6b and the insert boom 6c1, and the connection between the insert boom 6c2 and the main boom 6a. As for the connection, the connection work can be performed in the above procedure.

  On the other hand, when releasing the connection between the boom bodies, it is possible to release the connection between the boom bodies by a procedure reverse to the connection method described above.

(Features of this embodiment)
(1)
In the work attachment 3 of the present embodiment, the boom 6 is a split type boom having a plurality of boom bodies (a main boom 6a, a front boom 6b, and insert booms 6c1, 6c2). Like the insert boom 6c2 (the insert boom 6c1 having the same shape) and the main boom 6a of the above embodiment, the end in the longitudinal direction of the closed cross-sections 21 and 54 of the upper plates 21a and 54a constituting the upper surface of each boom body The front shielding parts 21a1 and 54a1 extending forward in the longitudinal direction from the part bend in a direction to close the open parts of the closed sectional parts 21 and 54, and the upper surfaces of the closed sectional parts 21 and 54 at the tips of the shielding parts 21a1 and 54a1 It is joined to the front plates 35 and 55 at a position deviating from the above. Therefore, even if a large bending stress occurs in the intermediate portions 21a3 and 54a2 constituting the upper surface of the boom body and the upper surface constituting portions 40 and 62 including the intermediate portions 21a3 and 54a2, the upper plates 21a and 54a located at the positions retracted from the upper surface of the boom body. The bending stress generated at the joining positions 36 and 59 is relatively smaller than the bending stress generated at the upper surface of the boom body. Therefore, it is possible to suppress a decrease in bending strength and fatigue strength of the portions at the joining positions 36 and 59, and it is possible to improve the fatigue life of each boom body and the entire boom 6.

  In particular, since the boom 6 receives the driving force from the base machine 2 and the weight of the arm 8 and the crushing device 9 provided at the front end side of the boom 6, when the attachment 3 is working in the standing state, the boom 6 On the upper surface and the like, a bending stress larger than that on the arm 8 or the like is generated. It is possible to improve the fatigue life of the boom 6 by suppressing a decrease in the bending strength and fatigue strength of the portion at the joint position 36 or the like that is weak in the boom 6.

  Moreover, since the joining position 36 and the like of the upper plate 21a and the front plate 35 is welding of the plates, it is difficult to improve the joining strength. However, as described above, the joining position 36 is from the upper surface of the boom 6. Since it is retracted inward, it is possible to suppress a decrease in bending strength and fatigue strength even in a welded portion between the plates.

(2)
Moreover, the joint positions 36 and 59 between the upper plates 21a and 54a of the boom bodies and the front plates 35 and 55 are located between the pair of side walls 22, and the bent portions 39 and 61 and both sides of the front plates 35 and 55 are located. Since the ends are joined to the side walls 22, the upper plates 21 a and 54 a and the front plates 35 and 55 are paired at the peripheral portions of the joining positions 36 and 59 between the upper plates 21 a and 54 a and the front plates 35 and 55. Since it is fixed by the side wall 22, it is possible to reduce the risk of breakage at the joining positions 36 and 59.

(3)
In the work attachment 3 of the present embodiment, the bent portions 39 and 61 of the insert boom 6c2 and the main boom 6a are upper surface components extending in the longitudinal direction in the upper plates 21a and 54a having the bent portions 39 and 61, respectively. 40 and 62 are bent so as to be inclined at an angle larger than 90 degrees and smaller than 180 degrees, so that the stress concentration on the bending top portions 38 and 58 in the bent portions 39 and 61 is reduced. It can be mitigated.

(Modification)
(A)
In the above-described embodiment, the split boom 6 having the plurality of boom bodies that can be connected to each other, that is, the main boom 6a, the front boom 6b, and the insert booms 6c1 and 6c2 has been described as an example. The present invention is not limited to this, and the present invention can be applied even to an integrated boom that is not divided into a plurality of boom bodies. In this case as well, the joining position of the upper plate and the front plate can be withdrawn from the upper surface of the boom, and the fatigue life of the boom can be improved.

(B)
In the above embodiment, the bent portions 39, 61 are formed at the front end portions of the upper plates 21a, 54a of the main boom 6a and the insert boom 6c2, and the front plates 35, 55 are formed at the tips of the bent portions 39, 61. Although an example in which welding is performed is shown, the present invention is not limited to this, and a bent portion is formed at the rear end portion of the upper plate of the boom body, and the joining position of the upper plate is determined. It may be bent in a direction to close the open portion of the closed cross-section so as to be retracted from the upper surface of the rear plate, and joined to the rear plate 37 or the like at a position away from the upper surface of the closed cross-sectional portion at the rear end. In that case, the rear plate corresponds to the shielding plate of the present invention. Even in that case, it is possible to suppress a decrease in the bending strength and fatigue strength of the portion at the joint position, and it is possible to improve the fatigue life of each boom body and the entire boom.

(C)
In the above embodiment, the bent portions 39 and 61 are formed on the upper plates 21a and 54a of the main boom 6a and the insert boom 6c2. However, the present invention is not limited to this, and these boom bodies are not limited thereto. The lower plate may be bent in a direction to close the open portion of the closed cross section so that a bent portion is formed on either of the front and rear end portions of the lower plate and the joining position of the lower plate is retracted from the lower surface of the boom body. In this case as well, it is possible to suppress a decrease in the bending strength and fatigue strength of the portion at the joining position, and it is possible to improve the fatigue life of each boom body and the entire boom.

(D)
In the above embodiment, the bent portions 39 and 61 are formed on the upper plates 21a and 54a of the main boom 6a and the insert boom 6c2 constituting the boom 6, but the present invention is not limited to this. None of the front and rear end portions of the member having a closed cross-section other than the boom 6 constituting the work attachment 3, for example, the upper plate and the lower plate constituting the respective closed cross-sections of the arm 8 and the inter boom 7. Forming a shield part bent in a direction to close the open part of the end in the longitudinal direction of the closed cross section, and joining the shield plate at the tip of the shield part, so that the joining position of the upper plate or the lower plate is You may make it evacuate from upper surfaces or lower surfaces, such as an arm. Also in this case, it is possible to suppress a decrease in the bending strength and fatigue strength of the portion at the joint position, and it is possible to improve the fatigue life of the arm or the like.

(E)
In the above embodiment, the dismantling machine has been described as an example of the working machine having the attachment of the present invention. However, the present invention is not limited to this, and the riff mag machine having a magnet attached to the tip of the attachment. The present invention can be widely applied to other work machines.

DESCRIPTION OF SYMBOLS 1 Dismantling machine 2 Base machine 3 Work attachment 4 Lower traveling body 5 Upper turning body 6 Boom 6a Main boom 6b Front boom 6c1, 6c2 Insert boom 7 Inter boom 8 Arm 9 Working device 21, 54 Closed section 21a, 54a Upper plate 21a1 , 54a1 Front shielding part (shielding part)
21a3, 54a2 Intermediate portion 21b, 54b Lower plate 21c, 21d, 54c, 54d Side plate 22 Front side wall (side wall)
23 Rear side walls 26, 56 Overhang portions 35, 55 Front plate (shield plate)
36, 59 Joining position 37, 57 Front end 38, 58 Bending top 39, 61 Bending part

Claims (6)

An attachment that can be undulated and attached to the base machine of a work machine,
A closed cross section composed of an upper plate, a lower plate, and left and right side plates ;
A shielding plate for closing a part of the open portion at the end in the longitudinal direction of the closed cross section ;
A pair of side walls provided so as to protrude forward or rearward of the closed cross-section along the side plates on both sides ,
The upper plate and / or the lower plate has a shielding portion bent in a direction to close the open portion of at least one of its end portions,
The open part is shielded by the shielding plate and the shielding part,
The shielding plate and the shielding part are joined at a position deviating from the upper surface or the lower surface of the closed cross section at the tip of the shielding part ,
The joint portion between the shielding plate and the shielding portion is disposed between the pair of side walls,
Both side ends of the shielding plate and the shielding part are joined to the mutually facing inner surfaces of the pair of side walls, respectively.
Attachment of work machine characterized by that. The shielding part of the upper plate or the lower plate is bent so as to be inclined at an angle larger than 90 degrees and smaller than 180 degrees.
The work machine attachment according to claim 1. The shielding portion of the upper plate bends in a direction to close the open portion of the closed cross section, and is joined to the shielding plate at a position deviating from the upper surface of the closed cross section at the tip of the shielding portion.
The work machine attachment according to claim 1 or 2.   The shielding portion on the front side of the upper plate is bent in a direction to close the opening portion of the closed cross section, and is joined to the shielding plate at a position away from the upper surface of the closed cross section at the tip of the shielding portion. The work machine attachment according to claim 3. The upper plate, the lower plate, the side plates on both the left and right sides, and the shielding plate constitute a boom that is attached to the base machine so as to be raised and lowered.
The work machine attachment according to claim 1 or 2. The boom has a plurality of boom bodies that can be detachably connected to each other along the longitudinal direction of the boom,
Each of the boom body, and the upper plate, said lower plate, said right and left side plates, and the shielding plate, and protrudes forward of the closed cross section, possible shapes connected to the front of the other boom member It has a pair of side walls having,
For each of the boom bodies, the shield part on the front side of the upper plate of the boom body bends in a direction to close the open part of the closed cross section, and the upper surface of the closed cross section at the tip of the shield part Bonded to the shielding plate at a position deviated from,
Both side ends of the shielding portion on the front side of the upper plate and both side ends of the shielding plate are joined to the side walls, respectively.
The work machine attachment according to claim 5.

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