JP5562903B2 - Construction machine arm - Google Patents

Description

  The present invention relates to a construction machine arm that is preferably used in a working device mounted on a construction machine such as a hydraulic excavator.

  In general, a hydraulic excavator, which is a typical example of a construction machine, includes a lower traveling body that can be self-propelled and an upper revolving body that is turnable on the lower traveling body, and includes a revolving frame that constitutes the upper revolving body. On the front side, a working device that performs excavation work such as earth and sand is provided so as to move up and down.

  Here, the excavator working device is usually provided with a boom whose base end is rotatably attached to the revolving frame, an arm rotatably attached to the distal end of the boom, and a distal end of the arm. A work tool such as a bucket that is rotatably attached, and a boom cylinder, an arm cylinder, and a bucket cylinder that drive the boom, arm, and bucket are roughly configured.

  The arm constituting such a working device is usually formed as a long welded structure having a total length of several meters. That is, the arm has left and right side plates, an upper plate joined by welding to the upper ends of the left and right side plates, a lower plate joined by welding to the lower ends of the left and right side plates, The right side plate and the rear plate joined to the rear end side of the upper plate by welding are formed as a box-shaped structure having a closed cross-sectional structure with a square cross section.

  Further, a boom connecting boss connected to the front end side of the boom using a connecting pin is provided on the lower rear side of the arm, and an arm cylinder is connected to the rear end side of the arm using a connecting pin. A cylinder bracket is provided, and a bucket cylinder bracket to which a bucket cylinder is connected using a connection pin is provided on the upper rear side of the arm (Patent Document 1).

JP 2003-261156 A

  By the way, since a boom connecting boss, an arm cylinder bracket, a bucket cylinder bracket, and the like are provided on the rear side of the arm, the strength required for the arm is large on the rear side and small on the front side.

  On the other hand, in the above-described arm according to the prior art, the upper plate and the lower plate are usually formed by using a single plate material such as a steel plate material having a uniform plate thickness. For this reason, on the front side of the arm, the plate thickness of the upper plate and the lower plate tends to be too thick with respect to the required strength, and there is a problem that the weight of the entire arm becomes larger than necessary.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an arm for a construction machine that can reduce the overall weight while ensuring a necessary strength.

In order to solve the above-described problems, the present invention provides a left and right side plate, an upper plate joined to the upper end side of the left and right side plates by welding, and a lower end side of the left and right side plates joined by welding. The lower plate is formed as a box-shaped structure having a quadrangular cross section by a rear plate joined by welding to the rear end side of the left and right side plates and the rear end side of the upper plate, Boom connecting bosses located on the lower rear side of the left and right side plates and welded to the left and right side plates, the rear end of the lower plate and the front end of the rear plate are provided. side plate, the bucket connecting bosses joined by welding to the front end of the upper and lower plates are provided, joined left and right pair of bucket cylinder bracket provided by welding on the outer surface of the upper plate, the upper plate is A rear thick upper plate made of a thick plate located on the rear side, and a plate located on the front side of the rear thick upper plate The bucket cylinder bracket is configured to be joined to the outer surface of the rear thick upper plate, and the lower plate is located on the rear side. The boom is formed by joining two members, a rear thick lower plate made of a thick plate material and a front thin lower plate made of a thin plate material located on the front side of the rear thick lower plate, coupling boss is applied to a construction machine arm comprising a configuration for joining to the rear end of the rear thick lower plate.

The left and right side plates of the invention according to claim 1 are characterized in that the left and right side plates are located on the rear side and are made of a thick plate material, and are located on the front side of the rear thick side plate and are thin. It is formed by joining two members, a front thin side plate made of a plate material, and the joining portion of the rear thick side plate and the front thin side plate is joined at its upper end to the rear thick upper plate and at its lower end to the rear thickness. The configuration is to join the lower plate.

The invention according to claim 2 is that a reinforcing internal partition wall is provided between the inner surface side of the rear thick upper plate and the boom connecting boss.

According to a third aspect of the present invention, the rear plate is formed as a thick rear plate using a plate material having a thickness equal to or greater than that of the rear thick upper plate and the rear thick side plate. The right rear thick side plate is joined to the rear end of the rear thick upper plate, and the front end of the thick rear plate is joined to the boom connecting boss.

According to the invention of claim 1 , the rear side that requires high strength among the upper plate and the lower plate constituting the arm is constituted by the rear thick upper plate and the rear thick lower plate having a large plate thickness, and the rear side The front side which does not require a large strength compared to the above can be constituted by a front thin upper plate and a front thin lower plate having a small plate thickness. As a result, for example, the upper plate is configured using a single plate material having a uniform plate thickness, and the lower plate is configured using a single plate material having a uniform plate thickness. It is possible to reduce the weight of the entire arm while ensuring the necessary strength on the rear side.

Further , since the left and right side plates are composed of two members, the rear thick side plate and the front thin side plate, the left and right side plates, the upper plate and the lower plate constituting the arm are configured to be thick on the rear side. The front side can be made thin. As a result, it is possible to further reduce the weight of the entire arm while ensuring the necessary strength on the rear side of the arm.

  Moreover, the rear thickness is obtained by joining the upper end of the joined portion between the rear thick side plate and the front thin side plate to the rear thick upper plate and joining the lower end of the joined portion between the rear thick side plate and the front thin side plate to the rear thick lower plate. The strength of the joint between the side plate and the front thin side plate can be increased, and the strength of the entire arm can be increased.

According to the invention of claim 2 , the boom connecting boss joined to the left and right side plates, the rear end of the lower plate, and the front end of the rear plate, and the rear thick upper plate are connected to each other by the internal partition. By doing so, the strength of the rear side of the arm provided with the boom connecting boss, the bucket cylinder bracket and the like can be increased.

According to the invention of claim 3 , by joining the front end of the thick rear plate having a thickness equal to or greater than the rear thick upper plate and the left and right rear thick lower plates to the boom connecting boss, The strength can be further increased.

It is a front view which shows the hydraulic shovel as a construction machine provided with the arm which concerns on this invention. It is a front view which shows an arm alone. It is the top view which looked at the arm from the arrow III-III direction in FIG. FIG. 4 is a cross-sectional view of the arm as viewed from the direction of arrows IV-IV in FIG. 3. FIG. 5 is an enlarged cross-sectional view illustrating a rear thick upper plate, a front thin upper plate, a rear thick lower plate, a front thin lower plate, a thick rear plate, and the like in FIG. 4. FIG. 6 is a cross-sectional view of the left and right side plates, the rear thick upper plate, the rear thick lower plate, and the like when viewed from the direction of arrows VI-VI in FIG. 5. It is a perspective view which shows the inside of an arm in the state which removed the right side board. It is a disassembled perspective view which decomposes | disassembles and shows the side plate which comprises an arm, an upper board, a lower board, a rear board, a boom connection boss | hub, an arm cylinder bracket, a bucket cylinder bracket.

  Hereinafter, an embodiment of a construction machine arm according to the present invention will be described in detail with reference to the accompanying drawings, taking as an example a case where the construction machine arm is applied to an arm of a hydraulic excavator.

  In the figure, reference numeral 1 denotes a hydraulic excavator as a typical example of a construction machine. The hydraulic excavator 1 is a self-propelled crawler-type lower traveling body 2 and an upper portion mounted on the lower traveling body 2 so as to be able to turn. The revolving unit 3 and the work device 4 provided so as to be able to be lifted and lowered on the front side of the revolving frame 3A serving as a base of the upper revolving unit 3 are roughly configured.

  The working device 4 includes a boom 5 whose base end is pin-coupled to the front side of the revolving frame 3 </ b> A so as to be able to move up and down, and an arm described later that has a base end pivotally connected to the tip of the boom 5. 11, a bucket 6 that is rotatably connected to the tip of the arm 11, a bucket link 7 provided between the tip of the arm 11 and the bucket 6, and the boom 5 with respect to the swing frame 3 </ b> A. The boom cylinder 8 is configured to move up and down, the arm cylinder 9 that rotates the arm 11 with respect to the boom 5, and the bucket cylinder 10 that rotates the bucket 6 with respect to the arm 11.

  Here, the bucket link 7 includes a rear link 7A having one end connected to the distal end side of the arm 11, and a front link 7B having one end connected to the other end of the rear link 7A and the other end connected to the bucket 6. It is configured. On the other hand, the bottom side of the bucket cylinder 10 is attached to a bucket cylinder bracket 23 of the arm 11 described later, and the rod side of the bucket cylinder 10 is connected to a connecting portion between the rear link 7A and the front link 7B of the bucket link 7. Yes.

  Next, the arm according to the present embodiment will be described with reference to FIGS.

  Reference numeral 11 denotes an arm rotatably attached to the tip of the boom 5. The arm 11 is formed as a long box-shaped structure that extends in the front and rear directions as a whole, and is rotated upward and downward with respect to the boom 5 by the arm cylinder 9.

  Here, the arm 11 is formed by left and right side plates 12 and 13, which will be described later, an upper plate 14, a lower plate 15, and a thick rear plate 16, and the arm 11 has a rectangular cross section as a whole. A box-shaped structure having a closed cross-sectional structure is formed. Further, a boom connecting boss 18, an arm cylinder bracket 22, a bucket cylinder bracket 23, etc., which will be described later, are provided on the rear side (boom 5 side) of the arm 11, and a later described side is provided on the front side (bucket 6 side) of the arm 11. A bucket connecting boss 20, a rear link connecting boss 21 and the like are provided.

  Reference numeral 12 denotes a left side plate constituting the left side surface of the arm 11, and the left side plate 12 extends in the front and rear directions while facing a right side plate 13 described later in the left and right directions. Here, as shown in FIG. 4 and FIG. 8, the left side plate 12 is positioned on the rear side in the front and rear direction, and a rear thick side plate 12A to which a boom connecting boss 18 described later is fixed, and the front side in the front and rear direction. It is formed by joining two members, a bucket connecting boss 20 described later and a front thin side plate 12B to which a rear link connecting boss 21 is fixed.

  The rear thick side plate 12A is formed by using a plate material such as a thick steel plate, and includes an upper plate joining portion 12A1, a lower plate joining portion 12A2, a rear plate joining portion 12A3, and a front thin side plate joining portion 12A4. It has an enclosed hexagonal shape. In this case, the front thin side plate joint portion 12A4 extends obliquely forward from the upper plate joint portion 12A1 toward the lower plate joint portion 12A2, thereby increasing the length of the joint portion between the rear thick side plate 12A and the front thin side plate 12B. It is configured to ensure. Further, a boom connecting boss joint 12A5 that is notched in an arc shape is provided at the corner where the lower plate joint 12A2 and the rear plate joint 12A3 intersect to join the flange 18B of the boom joint boss 18. ing.

  On the other hand, the front thin side plate 12B is formed using a plate material such as a steel plate having a thickness smaller than that of the rear thick side plate 12A, and includes an upper plate joining portion 12B1, a lower plate joining portion 12B2, and a bucket connecting boss joining portion 12B3. A quadrangular shape surrounded by the rear thick side plate joint 12B4 is formed. In this case, the rear thick side plate joint 12B4 extends obliquely forward from the upper plate joint 12B1 toward the lower plate joint 12B2. Further, a rear link connection boss joint 12B5 formed of a circular hole for joining the flange portion 21B of the rear link connection boss 21 is provided on the front end side of the front thin side plate 12B.

  Then, in the state in which the front thin side plate joint 12A4 of the rear thick side plate 12A and the rear thick side plate joint 12B4 of the front thin side plate 12B are butted together, butt welding is performed between the two, so that the rear thick side plate 12A and the front thin side plate 12A are joined together. A left side plate 12 is formed by joining two members with the side plate 12B.

  In this case, as shown in FIG. 6, if the plate thickness of the rear thick side plate 12A constituting the left side plate 12 is 12 At and the plate thickness of the front thin side plate 12 B is 12 Bt, the relationship between the plate thickness 12 At and the plate thickness 12 Bt is The following equation 1 is set.

  Reference numeral 13 denotes a right side plate constituting the right side surface of the arm 11, and the right side plate 13 has the same shape as the left side plate 12. That is, the right side plate 13 is located on the rear side in the front and rear direction and a rear thick side plate 13A to which a boom connecting boss 18 described later is fixed, and the bucket connecting boss 20 described later on the front side in the front and rear direction. It is formed by joining two members with the front thin side plate 13B to which the link connecting boss 21 is fixed.

  The rear thick side plate 13A is formed by using a plate material such as a thick steel plate, and includes an upper plate joint portion 13A1, a lower plate joint portion 13A2, a rear plate joint portion 13A3, and a front thin side plate joint portion 13A4. It has an enclosed hexagonal shape. In addition, boom connecting boss joints 13A5 that are notched in an arc shape are provided at the corners where the lower plate joint 13A2 and the rear plate joint 13A3 intersect.

  On the other hand, the front thin side plate 13B is formed by using a plate material such as a steel plate whose thickness is thinner than that of the rear thick side plate 13A, and includes an upper plate joint portion 13B1, a lower plate joint portion 13B2, and a bucket connecting boss joint portion 13B3. A quadrangular shape surrounded by the rear thick side plate joint portion 13B4 is formed. Further, a rear link connecting boss joint 13B5 made of a circular hole is provided on the front end side of the front thin side plate 13B.

  Then, in a state where the front thin side plate joint portion 13A4 of the rear thick side plate 13A and the rear thick side plate joint portion 13B4 of the front thin side plate 13B are butted together, butt welding is performed between the two, thereby the rear thick side plate 13A and the front thin side plate 13A are joined. A right side plate 13 is formed by joining two members to the side plate 13B.

  In this case, if the plate thickness of the rear thick side plate 13A constituting the right side plate 13 is 13 At and the plate thickness of the front thin side plate 13 B is 13 Bt, the relationship between the plate thickness 13 At and the plate thickness 13 Bt is as follows: Is set.

  Next, reference numeral 14 denotes an upper plate constituting the upper surface of the arm 11. The upper plate 14 is joined to the upper ends of the left and right side plates 12 and 13, and extends in the front and rear directions. Here, the upper plate 14 is positioned on the rear side in the front and rear directions, and a rear thick upper plate 14A to which a bucket cylinder bracket 23 described later is fixed, and a front thin upper plate 14B positioned on the front side in the front and rear directions. These two members are joined to each other.

  The rear thick upper plate 14A is formed in a rectangular plate shape that extends in the front and rear directions using a plate material such as a thick steel plate, and the rear portion of the bucket cylinder bracket 23 is slightly inclined downward. It is bent. Further, the rear edge of the rear thick upper plate 14A becomes a rear plate bonding portion 14A1 bonded to a thick rear plate 16 described later, and the front edge of the rear thick upper plate 14A is before bonded to the front thin upper plate 14B. The thin plate joining portion 14A2 is formed.

  On the other hand, the front thin upper plate 14B is formed in a rectangular flat plate shape extending in the front and rear directions by using a plate material such as a steel plate material whose thickness is thinner than that of the rear thick upper plate 14A. Further, the rear end edge of the front thin upper plate 14B becomes a rear thick upper plate joint portion 14B1, and the front end edge of the front thin upper plate 14B becomes a bucket connection boss joint portion 14B2 joined to a bucket connection boss 20 described later. Yes.

  Then, in the state in which the front thin upper plate joining portion 14A2 of the rear thick upper plate 14A and the rear thick upper plate joining portion 14B1 of the front thin upper plate 14B are abutted, butt welding is performed between the two, thereby increasing the rear thickness. An upper plate 14 is formed by joining two members, a plate 14A and a front thin upper plate 14B.

  In this case, as shown in FIG. 5, if the plate thickness of the rear thick upper plate 14A constituting the upper plate 14 is 14 At and the plate thickness of the front thin upper plate 14 B is 14 Bt, the plate thickness 14 At and the plate thickness 14 Bt are The relationship is set as shown in Equation 3 below.

  Next, reference numeral 15 denotes a lower plate constituting the lower surface of the arm 11, and this lower plate 15 is joined to the lower ends of the left and right side plates 12 and 13 and extends in the front and rear directions. Here, the lower plate 15 is formed by joining two members, a rear thick lower plate 15A located on the rear side in the front and rear directions and a front thin lower plate 15B located on the front side in the front and rear directions. ing.

  The rear thickness lower plate 15A is formed in a rectangular flat plate shape extending in the front and rear directions by using a plate material such as a steel plate material having a large plate thickness. Further, the rear end edge of the rear thick lower plate 15A becomes a boom connection boss joint 15A1 joined to a boom connection boss 18 described later, and the front end edge of the rear thick lower plate 15A is joined to the front thin lower plate 15B. It is a front thin lower plate joint 15A2.

  On the other hand, the front thin lower plate 15B is formed in a rectangular flat plate shape extending in the front and rear directions using a plate material such as a steel plate having a thickness smaller than that of the rear thickness lower plate 15A. Further, the rear end edge of the front thin lower plate 15B is a rear thickness lower plate joint portion 15B1, and the front end edge of the front thin lower plate 15B is a bucket connection boss joint portion 15B2 joined to a bucket connection boss 20 described later. Yes.

  Then, in the state in which the front thin lower plate joint 15A2 of the rear thin lower plate 15A and the rear thickness lower plate joint 15B1 of the front thin lower plate 15B are butted together, butt welding is performed between the two, A lower plate 15 is formed by joining two members of the plate 15A and the front thin lower plate 15B.

  In this case, as shown in FIG. 5, when the plate thickness of the rear thick lower plate 15A constituting the lower plate 15 is 15 At and the plate thickness of the front thin lower plate 15 B is 15 Bt, the plate thickness 15 At and the plate thickness 15 Bt are The relationship is set as shown in Equation 4 below.

  Next, reference numeral 16 denotes a thick rear plate constituting the rear surface of the arm 11, and the thick rear plate 16 is formed in a rectangular plate shape using a plate material such as a steel plate material, and the central portion in the length direction is a square shape. (See FIG. 5). The thickness 16t of the thick rear plate 16 is the thickness 12At of the rear thick side plate 12A constituting the left side plate 12, the plate thickness 13At of the rear thick side plate 13A constituting the right side plate 13, and the rear thickness constituting the upper plate 14. The thickness 14At of the plate 14A and the thickness 15At of the rear thickness lower plate 15A constituting the lower plate 15 are equal to or greater than those, and are set as shown in the following equation (5).

  Here, the thick rear plate 16 is joined to the rear end sides of the left and right side plates 12 and 13 and the upper plate 14 by welding, and closes the rear end portion of the hollow arm 11. In this case, the thick rear plate 16 constitutes the rear plate joining portion 12A3 of the rear thick side plate 12A constituting the left side plate 12, the rear plate joining portion 13A3 of the rear thick side plate 13A constituting the right side plate 13, and the upper plate 14. The rear thick upper plate 14A is joined to the rear plate joint portion 14A1 by welding. Further, the front end edge of the thick rear plate 16 serves as a boom connection boss joint 16A joined to a boom connection boss 18 described later, and an arm cylinder bracket 22 described later is fixed to the outer surface of the thick rear plate 16. It has become.

  Then, fillet welding is performed between the upper plate joining portion 12A1 and the upper plate 14 of the rear thick side plate 12A constituting the left side plate 12, and between the upper plate joining portion 12B1 and the upper plate 14 of the front thin side plate 12B. By performing fillet welding between the upper plate joining portion 13A1 and the upper plate 14 of the rear thick side plate 13A constituting the right side plate 13, and between the upper plate joining portion 13B1 and the upper plate 14 of the front thin side plate 13B. The upper plate 14 is firmly joined to the upper ends of the left and right side plates 12 and 13.

  In addition, fillet welding is performed between the lower plate joining portion 12A2 and the lower plate 15 of the rear thick side plate 12A constituting the left side plate 12, and between the lower plate joining portion 12B2 and the lower plate 15 of the front thin side plate 12B. By performing fillet welding between the lower plate joining portion 13A2 and the lower plate 15 of the rear thick side plate 13A constituting the right side plate 13 and between the lower plate joining portion 13B2 and the lower plate 15 of the front thin side plate 13B. The lower plate 15 is firmly joined to the lower ends of the left and right side plates 12 and 13.

  Further, between the rear plate joining portion 12A3 and the thick rear plate 16 of the rear thick side plate 12A constituting the left side plate 12, and between the rear plate joining portion 13A3 and the thick rear plate 16 of the rear thick side plate 13A constituting the right side plate 13. The left and right side plates 12 and 13 and the upper plate 14 are formed by performing fillet welding between the rear plate joint portion 14A1 of the rear thick upper plate 14A and the thick rear plate 16 constituting the upper plate 14, respectively. The thick rear plate 16 is firmly joined to the rear end side.

  Here, as shown in FIGS. 4 and 5, when looking at the joint between the rear thick side plate 12 </ b> A and the front thin side plate 12 </ b> B constituting the left side plate 12, the upper end portion 12 </ b> C of the joint portion is the rear of the upper plate 14. It joins in the position of the middle part of thick upper board 14A, and lower end part 12D of a joined part is joined in the position of the front part side of rear thickness lower board 15A of lower board 15. On the other hand, as shown in FIG. 2, regarding the joint between the rear thick side plate 13 </ b> A and the front thin side plate 13 </ b> B constituting the right side plate 13, the upper end portion 13 </ b> C of this joint is the rear thick upper plate 14 </ b> A of the upper plate 14. The lower end portion 13D of the joined portion is joined at a position on the front side of the lower thickness lower plate 15A of the lower plate 15.

  Reference numeral 17 denotes left and right backing materials provided between the rear thick side plates 12A and 13A and the thick rear plate 16 respectively of the left and right side plates 12 and 13. The backing material 17 is formed, for example, by bending an elongated square member into a substantially square shape, and is fixed to the inner surfaces of the rear plate joint portions 12A3 and 13A3 of the rear thick side plates 12A and 13A by spot welding or the like.

  When the rear plate joint 12A3 of the rear thick side plate 12A constituting the left side plate 12 is welded to the thick rear plate 16, the rear plate joint 12A3 is completely welded using the backing material 17, and the right side When the rear plate joint 13A3 of the rear thick side plate 13A constituting the plate 13 is welded to the thick rear plate 16, the rear plate joint 12A3 is completely welded using the backing material 17.

  Reference numeral 18 denotes a boom connecting boss provided on the lower rear side of the left and right side plates 12 and 13, and the boom connecting boss 18 is rotatable between the boom 5 and the arm 11 shown in FIG. A connecting pin (not shown) that is connected to is inserted. Here, the boom connecting boss 18 includes left and right hollow cylindrical boss portions 18A extending in the left and right directions and arc-shaped flat plates provided on both left and right ends of the cylindrical boss portion 18A. It is comprised by the flange part 18B.

  Then, the cylindrical boss portion 18A of the boom connection boss 18 is joined to the boom connection boss joint portion 15A1 of the rear thick lower plate 15A constituting the lower plate 15 and the boom connection boss joint portion 16A of the thick rear plate 16 by welding. ing. Further, the left and right flange portions 18B of the boom connecting boss 18 are joined to the boom connecting boss joint 12A5 of the rear thick side plate 12A constituting the left side plate 12 and the boom connecting boss joint of the rear thick side plate 13A constituting the right side plate 13, respectively. It is joined to the part 13A5 by welding.

  Reference numeral 19 denotes an internal partition provided between the inner surface of the upper plate 14 and the boom connection boss 18, and the internal partition 19 is disposed so as to form two closed spaces in the arm 11, and the rigidity of the arm 11 is determined. It is what raises. The internal partition wall 19 is a rectangular flat plate having a width dimension in the left and right directions substantially equal to the distance between the left and right side plates 12 and 13.

  Here, as shown in FIGS. 4 and 5, the upper end portion 19 </ b> A of the internal partition wall 19 is welded to the vicinity of the joint portion with the front thin upper plate 14 </ b> B of the rear thick upper plate 14 </ b> A constituting the upper plate 14. The lower end portion 19B of the inner partition wall 19 is joined to the cylindrical boss portion 18A of the boom connecting boss 18 by welding. On the other hand, the left and right side end portions of the inner partition wall 19 are joined to the rear thick side plate 12A and the front thin side plate 12B constituting the left side plate 12 by welding, and the rear thick side plate 13A constituting the right side plate 13 is joined. It is joined to the front thin side plate 13B by welding.

  Reference numeral 20 denotes a bucket connecting boss provided at the front end portions of the left and right side plates 12, 13, the upper plate 14 and the lower plate 15. The bucket connecting boss 20 is located between the bucket 6 and the arm 11 shown in FIG. A connecting pin (not shown) for rotatably connecting the two is inserted. The bucket connecting boss 20 includes a hollow cylindrical boss portion 20A extending in the left and right directions, and flat left and right flange portions 20B provided on both left and right ends of the cylindrical boss portion 20A. It is configured.

  Here, the cylindrical boss portion 20 </ b> A of the bucket connection boss 20 includes a bucket connection boss joint portion 14 </ b> B <b> 2 of the front thin upper plate 14 </ b> B constituting the upper plate 14 and a bucket connection boss joint of the front thin lower plate 15 </ b> B constituting the lower plate 15. It is joined to the part 15B2 by welding. The left and right flanges 20B of the bucket connection boss 20 are joined to the bucket connection boss joint 12B3 of the front thin side plate 12B constituting the left side plate 12 and the bucket connection boss joint of the front thin side plate 13B constituting the right side plate 13. It is joined to the part 13B3 by welding.

  Reference numeral 21 denotes a rear link connecting boss provided on the front end side of the left and right side plates 12 and 13 adjacent to the bucket connecting boss 20, and the rear link connecting boss 21 is a rear link of the bucket link 7 shown in FIG. A connecting pin (not shown) that rotatably connects between 7A and the arm 11 is inserted. Here, the rear link connecting boss 21 includes a hollow cylindrical boss portion 21A extending in the left and right directions, and disc-shaped left and right flanges provided on both left and right ends of the cylindrical boss portion 21A. It is comprised by the part 21B. The left and right flange portions 21B of the rear link connecting boss 21 are the rear link connecting boss joint 12B5 of the front thin side plate 12B constituting the left side plate 12 and the rear link of the front thin side plate 13B constituting the right side plate 13. It is joined to the connecting boss joint 13B5 by welding.

  Reference numeral 22 denotes a pair of left and right arm cylinder brackets provided on the outer surface of the thick rear plate 16. Each of the arm cylinder brackets 22 is such that the rod tip of the arm cylinder 9 shown in FIG. 1 is rotatably connected via a connecting pin (not shown). Here, each arm cylinder bracket 22 is formed as a plate having a substantially triangular shape using a plate material such as a steel plate material, and a pin insertion hole 22A for inserting the above-described connecting pin is formed at the tip side thereof. It is installed. The pair of left and right arm cylinder brackets 22 are joined to the outer surface of the thick rear plate 16 by welding in a state where a certain distance is maintained in the left and right directions.

  Reference numeral 23 denotes a pair of left and right bucket cylinder brackets provided on the outer surface on the rear end side of the upper plate 14. Each bucket cylinder bracket 23 is connected to the bottom side of the bucket cylinder 10 shown in FIG. 1 so as to be rotatable via a connecting pin (not shown). Here, each bucket cylinder bracket 23 is formed as a plate having a substantially triangular shape using a plate material such as a steel plate material, and a pin insertion hole 23A for inserting the above-described connecting pin is formed at the tip side thereof. It is installed. The pair of left and right bucket cylinder brackets 23 are joined to the outer surface of the rear thick upper plate 14A constituting the upper plate 14 by welding in a state where a constant interval is maintained in the left and right directions.

  Next, reference numeral 24 denotes an auxiliary welding member provided on the outer surface of the rear end side of the upper plate 14, and the auxiliary welding member 24 is formed of a flat plate having a substantially M shape in plan view as shown in FIG. Yes. The auxiliary welding member 24 is joined to the outer surface of the rear thick upper plate 14A by welding so as to surround a welded portion between the rear thick upper plate 14A of the upper plate 14 and each bucket cylinder bracket 23.

  And when joining between the auxiliary welding member 24 and the rear thick upper plate 14A by welding, a weld portion (weld bead portion) formed between each bucket cylinder bracket 23 and the rear thick upper plate 14A, By burying a gap formed between the auxiliary welding member 24 and the rear thick upper plate 14A with a weld bead, the joining strength of each bucket cylinder bracket 23 to the upper plate 14 can be increased. .

  The arm 11 according to the present embodiment has the above-described configuration, and an example of a procedure for manufacturing the arm 11 will be described with reference to FIG.

  First, butt welding is performed between the front thin side plate joint 12A4 of the rear thick side plate 12A constituting the left side plate 12 and the rear thick side plate joint 12B4 of the front thin side plate 12B. Thereby, the left side plate 12 in which the two members of the rear thick side plate 12A and the front thin side plate 12B are joined can be formed. Further, butt welding is performed between the front thin side plate joint portion 13A4 of the rear thick side plate 13A constituting the right side plate 13 and the rear thick side plate joint portion 13B4 of the front thin side plate 13B. Thereby, the right side plate 13 in which the two members of the rear thick side plate 13A and the front thin side plate 13B are joined can be formed. In this case, the backing material 17 is provided on the inner surface of the rear plate joint portion 12A3 of the rear thick side plate 12A constituting the left side plate 12 and the inner surface of the rear plate joint portion 13A3 of the rear thick side plate 13A constituting the right side plate 13, respectively. It is fixed in advance by spot welding or the like.

  Next, the boom connecting boss joint 12A5 provided on the rear thick side plate 12A of the left side plate 12 and the boom connecting boss joint 13A5 provided on the rear thick side plate 13A of the right side plate 13 are moved to the left of the boom connecting boss 18, The right flange portion 18B is joined by welding. Further, the rear link connecting boss joint 12B5 provided on the front thin side plate 12B of the left side plate 12 and the rear link connecting boss joint 13B5 provided on the front thin side plate 13B of the right side plate 13 are connected to the rear link connecting boss 21. The left and right flange portions 21B are joined by welding. Further, the bucket connection boss joint 12B3 provided on the front thin side plate 12B of the left side plate 12 and the bucket connection boss joint 13B3 provided on the front thin side plate 13B of the right side plate 13 are compared with the left and right sides of the bucket connection boss 20. The flange portions 20B are joined by welding.

  On the other hand, in the state where the front thin upper plate joint 14A2 of the rear thick upper plate 14A constituting the upper plate 14 and the rear thick upper plate joint 14B1 of the front thin upper plate 14B are butted, butt welding is performed between them. . Thereby, the upper plate 14 in which the two members of the rear thick upper plate 14A and the front thin upper plate 14B are joined can be formed.

  Next, butt welding is performed between the front thin lower plate joint 15A2 of the rear thin lower plate 15A constituting the lower plate 15 and the rear thin lower plate joint 15B1 of the front thin lower plate 15B. Apply. Thereby, the lower plate 15 in which the two members of the rear thick lower plate 15A and the front thin lower plate 15B are joined can be formed.

  Next, the upper plate 14 is disposed on the upper end side of the left side plate 12 and the right side plate 13, and the upper plate joining portion 12A1 of the rear thick side plate 12A and the upper plate joining portion 12B1 of the front thin side plate 12B constituting the left side plate 12; Then, fillet welding is performed between the upper plate 14 and the entire length. Further, fillet welding is performed over the entire length between the upper plate joining portion 13A1 of the rear thick side plate 13A and the upper plate joining portion 13B1 of the front thin side plate 13B and the upper plate 14 constituting the right side plate 13. Further, the bucket connecting boss joint 14B2 of the front thin upper plate 14B constituting the upper plate 14 is joined to the cylindrical boss 20A of the bucket connecting boss 20 by welding. Thereby, the upper plate 14 can be joined to the upper end sides of the left and right side plates 12 and 13.

  On the other hand, an internal partition wall 19 is prepared, and the upper end portion 19A of the internal partition wall 19 is welded to the vicinity of the joint portion of the rear thick upper plate 14A constituting the upper plate 14 with the front thin upper plate 14B. The lower end portion 19B of the partition wall 19 is welded to the cylindrical boss portion 18A of the boom connection boss 18. Further, the left and right side end portions 19C of the inner partition wall 19 are welded to the inner surfaces of the rear thick side plate 12A and the front thin side plate 12B constituting the left side plate 12, and the rear thick side plate 13A constituting the right side plate 13 and It welds to the inner surface with the front thin side plate 13B.

  Next, the lower plate 15 is disposed on the lower end side of the left side plate 12 and the right side plate 13, and the lower plate joining portion 12A2 of the rear thick side plate 12A and the lower plate joining portion 12B2 of the front thin side plate 12B constituting the left side plate 12 Then, fillet welding is performed between the lower plate 15 and the entire length. Further, fillet welding is performed over the entire length between the lower plate joining portion 13A2 of the rear thick side plate 13A and the lower plate joining portion 13B2 of the front thin side plate 13B and the lower plate 15 constituting the right side plate 13. Further, the boom connecting boss joint 15A1 of the rear thick lower plate 15A constituting the lower plate 15 is joined to the cylindrical boss portion 18A of the boom connecting boss 18 by welding, and the front thin lower plate 15B constituting the lower plate 15 is joined. Bucket connection boss joint 15B2 is joined to cylindrical boss 20A of bucket connection boss 20 by welding. Thereby, the lower plate 15 can be joined to the lower end sides of the left and right side plates 12 and 13.

  Thus, after joining the upper board 14 to the upper end side of the left and right side boards 12 and 13, and joining the lower board 15 to the lower end side, the thick rear board 16 is prepared. In the state where the backing material 17 fixed to the rear thick side plate 12A of the left side plate 12 and the thick rear plate 16 are brought into contact with each other, the rear plate joining portion 12A3 of the rear thick side plate 12A and the thick rear plate 16 are interposed. Apply fillet welding. Further, in a state where the backing material 17 fixed to the rear thick side plate 13A of the right side plate 13 and the thick rear plate 16 are brought into contact with each other, the rear plate joining portion 13A3 of the rear thick side plate 13A and the thick rear plate 16 are interposed. Apply fillet welding. On the other hand, fillet welding is performed between the rear plate joint 14A1 of the rear thick upper plate 14A and the thick rear plate 16 constituting the upper plate 14, and the boom connection boss joint 16A of the thick rear plate 16 is connected to the boom. The cylindrical boss portion 18A of the boss 18 is welded.

  Next, a pair of left and right bucket cylinder brackets 23 are joined to the outer surface of the rear thick upper plate 14A constituting the upper plate 14 by welding. Further, an M-shaped auxiliary welding member 24 is arranged on the outer surface of the rear thick upper plate 14A so as to surround the welded portion between the rear thick upper plate 14A and each bucket cylinder bracket 23, and the auxiliary welding member 24 is made to have a rear thickness. By welding to the upper plate 14A, the joining strength of each bucket cylinder bracket 23 to the rear thick upper plate 14A is increased. Further, a pair of left and right arm cylinder brackets 22 are joined to the outer surface of the thick rear plate 16 by welding.

  In this way, the left and right side plates 12, 13, the upper plate 14, the lower plate 15, the thick rear plate 16, and the like are welded together to form the arm 11 having a closed cross-sectional structure with a quadrangular cross section. Can do.

  In this case, according to the present embodiment, the upper plate 14 constituting the arm 11 is joined to the rear thick upper plate 14A having a large plate thickness 14At and the front thin upper plate 14B having a small plate thickness 14Bt by welding. The bucket cylinder bracket 23 to which the bucket cylinder 10 is connected is joined to the outer surface of the rear thick upper plate 14A.

  Thus, the rear side that requires a large strength of the upper plate 14 that constitutes the arm 11 is configured by the rear thickness upper plate 14A, and the front side that does not require a large strength compared to the rear side, It can be constituted by the front thin upper plate 14B. Accordingly, the required strength can be ensured by the rear thick upper plate 14A on the rear side of the arm 11, and the weight can be reduced by the front thin upper plate 14B on the front side of the arm 11. As a result, the weight of the entire arm 11 can be reduced while maintaining the necessary strength, as compared with the case where the upper plate is formed using a single plate material having a uniform plate thickness, for example.

  In addition, according to the present embodiment, the lower plate 15 constituting the arm 11 also joins the rear thin lower plate 15A having a large plate thickness 15At and the front thin lower plate 15B having a small plate thickness 15Bt by welding. It is formed by. Further, the left side plate 12 constituting the arm 11 is formed by welding a rear thick side plate 12A having a large plate thickness 12At and a front thin side plate 12B having a small plate thickness 12Bt by welding, and the right side plate 13 is also large. The rear thick side plate 13A having a plate thickness 13At and the front thin side plate 13B having a small plate thickness 13Bt are joined by welding.

  Thereby, on the rear side of the arm 11 provided with the boom connecting boss 18, the arm cylinder bracket 22, the bucket cylinder bracket 23, etc., the necessary strength is secured by the rear thick lower plate 15A and the left and right rear thick side plates 12A and 13A. On the front side of the arm 11, the weight can be reduced by the front thin lower plate 15B and the left and right front thin side plates 12B and 13B. Therefore, for example, as compared with the case where the lower plate is formed using a single plate material having a uniform plate thickness, the arm 11 as a whole can be further reduced in weight while maintaining the necessary strength.

  Moreover, when looking at the joint between the rear thick side plate 12A and the front thin side plate 12B constituting the left side plate 12, the upper end portion 12C of this joint is joined to the rear thick upper plate 14A of the upper plate 14, The lower end 12D is configured to be joined to the rear thick lower plate 15A of the lower plate 14 (see FIG. 4). On the other hand, regarding the joint portion between the rear thick side plate 13A and the front thin side plate 13B constituting the right side plate 13, the upper end portion 13C of the joint portion is joined to the rear thick upper plate 14A of the upper plate 14, and The lower end portion 13D is configured to be joined to the lower thickness lower plate 15A of the lower plate 14 (see FIG. 2).

  As a result, the strength of the joint between the rear thick side plate 12A and the front thin side plate 12B of the left side plate 12 can be increased, and the strength of the joint between the rear thick side plate 13A and the front thin side plate 13B of the right side plate 13 can be increased. The strength of the entire arm 11 can be increased.

  In addition, according to the present embodiment, the rear thick side plates 12A and 13A of the left and right side plates 12 and 13, the boom connecting boss joint 15A1 which is the rear end of the rear thick lower plate 15A of the lower plate 15, and the thickness An internal partition wall 19 is provided between the boom connection boss 18 to which the boom connection boss joint 16A serving as the front end of the rear plate 16 is joined and the rear thick upper plate 14A constituting the upper plate 14. As a result, two closed spaces can be formed in the arm 11 by the internal partition wall 19, and the rigidity of the entire arm 11 can be increased.

  Further, according to the present embodiment, the thick rear plate 16 is replaced with the rear thick side plates 12A and 13A of the left and right side plates 12 and 13, the rear thick upper plate 14A of the upper plate 14, and the rear thick lower plate of the lower plate 15. The boom connecting boss joint 16A, which is a front end of the thick rear plate 16, is joined to the boom connecting boss 18 by welding. Thereby, the intensity | strength of the rear-end part of the arm 11 in which the arm cylinder bracket 22 is provided can be raised further.

  In the above-described embodiment, as an example of the procedure for assembling the arm 11, the boom connecting boss 18, the bucket connecting boss 20, and the rear link connecting boss 21 are joined to the left and right side plates 12 and 13, and then each side plate 12 is joined. , 13 and the upper plate 14, the inner partition wall 19 is bonded between the upper plate 14 and the boom connecting boss 18, and then the lower plate 15 and the thick rear plate 16 are bonded to the side plates 12 and 13. Illustrated. However, the procedure for assembling the arm 11 according to the present invention is not limited to this embodiment, and the procedure for assembling the arm 11 can be changed as appropriate.

  Moreover, in embodiment mentioned above, by fixing backing material 17 to back thickness side plate 12A, 13A which comprises the left and right side plates 12 and 13, each back thickness side plate is utilized using this backing material 17. A configuration in which 12A and 13A are completely welded to the thick rear plate 16 is illustrated. However, the present invention is not limited to this, and fillet welding may be performed between the rear thick side plates 12A and 13A and the thick rear plate 16 without using the backing material 17.

  Further, in the above-described embodiment, the crawler type hydraulic excavator 1 is described as an example of the construction machine. However, the present invention is not limited to this, and other construction machines such as an arm used for a wheel type hydraulic excavator, for example. It can be widely applied to the arm for use.

1 Excavator (construction machine)
11 Arm 12 Left side plate 12A, 13A Rear thick side plate 12B, 13B Front thin side plate 13 Right side plate 14 Upper plate 14A Rear thick upper plate 14B Front thin upper plate 15 Lower plate 15A Rear thick lower plate 15B Front thin lower plate 16 Thick rear plate 18 Boom connection boss 19 Internal partition 20 Bucket connection boss 23 Bucket cylinder bracket

Claims (3)

Left and right side plates, an upper plate joined to the upper ends of the left and right side plates by welding, a lower plate joined by welding to the lower ends of the left and right side plates, and the left and right side plates Formed as a box-shaped structure having a quadrangular cross section by a rear plate joined by welding to the rear end side of the side plate and the rear end side of the upper plate,
Located at the rear lower side of the left and right side plates, provided with a boom connecting boss joined by welding to the left and right side plates, the rear end of the lower plate and the front end of the rear plate,
Provided with a bucket connecting boss joined by welding to the front ends of the left and right side plates, the upper plate and the lower plate,
Left joined by welding to the outer surface of the upper plate, a pair of right bucket cylinder bracket provided,
The upper plate is composed of two members, a rear thick upper plate made of a thick plate material located on the rear side and a front thin upper plate made of a thin plate material located on the front side of the rear thick upper plate. Formed by joining,
The bucket cylinder bracket is configured to be joined to an outer surface of the rear thick upper plate,
The lower plate is composed of two members: a rear thick lower plate made of a thick plate material located on the rear side, and a front thin lower plate made of a thin plate material located on the front side of the rear thick lower plate. Formed by joining,
The boom connecting boss, a construction machine arm comprising a configuration for joining to the rear end of the rear thick lower plate,
The left and right side plates are two members, a rear thick side plate made of a thick plate material located on the rear side, and a front thin side plate made of a thin plate material located on the front side of the rear thick side plate. Formed by joining,
The construction machine arm according to claim 1, wherein the joining portion between the rear thick side plate and the front thin side plate is configured such that an upper end thereof is joined to the rear thick upper plate and a lower end thereof is joined to the rear thick lower plate . The construction machine arm according to claim 1 , wherein a reinforcing internal partition is provided between an inner surface side of the rear thick upper plate and the boom connecting boss. The rear plate is formed as a thick rear plate using a plate material having a thickness equal to or greater than that of the rear thick upper plate and the rear thick side plate,
The thick rear plate is joined to the rear end of the left and right rear thick side plates and the rear end of the rear thick upper plate, and the front end of the thick rear plate is joined to the boom connecting boss. Item 3. The construction machine arm according to Item 1 or 2 .

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