JP5511732B2 - 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.

  On the other hand, when the plate thickness of the upper plate, the lower plate, the bucket cylinder bracket and the like constituting the arm is reduced, the weight of the arm can be reduced. However, the bucket cylinder bracket is joined to the upper plate of the arm by welding, and a large load due to expansion and contraction of the bucket cylinder acts. For this reason, the bucket cylinder bracket and the upper plate formed using a thin plate material are easily deformed, and a large stress acts on the welded portion (weld bead) between the bucket cylinder bracket and the upper plate. There exists a problem that durability of the whole arm containing a bucket cylinder bracket falls.

  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. A bucket connecting boss joined by welding to the front ends of the side plate, the upper plate and the lower plate, and a pair of left and right bucket cylinder brackets joined by welding to the outer surface of the rear end side of the upper plate. Applicable to construction machinery arms.

  A feature of the invention of claim 1 is that a flat auxiliary welding member is provided on the outer surface of the rear side of the upper plate so as to surround the welded portion between the pair of left and right bucket cylinder brackets and the upper plate. And providing a fillet weld around the auxiliary welding member.

  According to a second aspect of the present invention, there is provided a reinforcing internal partition wall between the boom connecting boss and a position on the inner surface side of the upper plate and on the front side of the position of the connecting pin provided on the bucket cylinder bracket. The rear end of the auxiliary welding member is configured to extend to the rear side of the upper end position of the internal partition wall.

  According to a third aspect of the present invention, a gap generated between the bucket cylinder bracket and the auxiliary welding member on the outer surface of the upper plate is embedded by a welding bead of the bucket cylinder bracket and a welding bead of the auxiliary welding member. It is in the configuration.

  According to a fourth aspect of the present invention, the auxiliary welding member is formed in an M shape in a plan view, and a front side of the M-shaped auxiliary welding member is provided with a notch that is recessed in a concave shape toward the rear. It is to have done.

  According to the invention of claim 1, by providing the auxiliary welding member, it is possible to partially increase the plate thickness of the portion of the upper plate where the bucket cylinder brackets are joined. Thereby, it can suppress that an upper board and each bucket cylinder bracket deform | transform greatly with the load which acts on each bucket cylinder bracket, and can improve durability of the whole arm. In addition, by performing fillet welding around the auxiliary welding member surrounding the welded portion between each bucket cylinder bracket and the upper plate, the welded portion between each bucket cylinder bracket and the upper plate is connected to the auxiliary welding member and the upper plate. It can be reinforced by weld beads formed therebetween. For this reason, the stress which arises in the welding part of each bucket cylinder bracket and an upper board can be reduced. As a result, the strength of the upper plate and each bucket cylinder bracket can be increased without increasing the thickness of the upper plate and each bucket cylinder bracket, and the overall weight of the arm can be reduced while ensuring the necessary strength. Can do.

  According to the invention of claim 2, by providing the internal partition wall between the boom connecting boss and the inner surface of the upper plate, the inner partition wall can prevent the upper plate from being deformed so as to sink into the inner surface side. In this case, since the rear end of the auxiliary welding member extends to the rear side of the upper end position of the inner partition wall, the effect of increasing the plate thickness of the upper plate by the auxiliary welding member and the inner surface of the upper plate by the inner partition wall The effect of supporting from the side can be obtained at the same time, and the strength of the upper plate, each bucket cylinder bracket and the auxiliary welding member can be further increased.

  According to the invention of claim 3, the gap between the bucket cylinder bracket joined to the outer surface of the upper plate and the auxiliary welding member is divided into a weld bead formed between the bucket cylinder bracket and the upper plate, and auxiliary welding. It can be embedded by a weld bead formed between the member and the top plate. Thereby, the weld bead formed between the bucket cylinder bracket and the upper plate, the weld bead formed between the auxiliary welding member and the upper plate can be integrated. As a result, when a load is applied to the bucket cylinder bracket, stress can be prevented from concentrating on the weld bead between the bucket cylinder bracket and the upper plate, and the bonding strength of the bucket cylinder bracket to the upper plate is increased. be able to.

  According to the invention of claim 4, since the concave cutout is provided on the front side of the M-shaped auxiliary welding member, a large weld length is secured by performing fillet welding around the auxiliary welding member. can do. As a result, the joining strength of the auxiliary welding member to the upper plate can be increased, and the strength of the welded portion between the upper plate and the bucket cylinder bracket reinforced by the auxiliary welding member 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. It is a principal part enlarged view which expands and shows the upper board, bucket cylinder bracket, auxiliary | assistant welding member, etc. in FIG. It is sectional drawing which looked at the welding part of the upper board, the bucket cylinder bracket, and the auxiliary welding member from the arrow XX direction in FIG. It is sectional drawing which shows the state which arrange | positions an auxiliary welding member in the vicinity of the welding part of an upper board and a bucket cylinder bracket. It is sectional drawing which shows the state which welds between the welding bead between an upper board and a bucket cylinder bracket, and an auxiliary welding member. It is a principal part enlarged view similar to FIG. 9 which shows the modification of an auxiliary welding member.

  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 provided on the arm 11 described later using a connecting pin 10A, and the rod side of the bucket cylinder 10 is connected to the rear link 7A and the front link of the bucket link 7. 7B is connected using a connecting pin 10B.

  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. 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. 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 the 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. In addition, a boom connection boss joint 12A5 that is cut out 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 connection 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. Also, a bucket cylinder bracket 23 described later is joined to the outer surface 14A3 of the rear thick upper plate 14A, and an upper end portion 19A of an inner partition wall 19 described later is joined to the inner surface 14A4 of the rear thick upper plate 14A.

  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.

  Next, reference numeral 19 denotes an internal partition wall provided between the inner surface 14A4 of the rear thick upper plate 14A constituting the upper plate 14 and the boom connecting boss 18, and the internal partition wall 19 includes two closed spaces in the arm 11. Is arranged to increase the rigidity of the arm 11. 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.

  As shown in FIGS. 4 and 5, the upper end portion 19A of the inner partition wall 19 is joined by welding to a portion of the inner surface 14A4 of the rear thick upper plate 14A in the vicinity of the joint portion with the front thin upper plate 14B. The lower end 19B of 19 is joined to the cylindrical boss 18A of the boom connecting boss 18 by welding. Here, the upper end portion 19A of the internal partition wall 19 is positioned in front of a pin insertion hole 23A of the bucket cylinder bracket 23 described later, that is, in position in front of the connecting pin 10A to which the bucket cylinder 10 shown in FIG. 1 is connected. Thus, it is joined to the inner surface 14A4 of the rear thick upper plate 14A.

  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 14A3 of the rear thick upper plate 14A constituting 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 10A. 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 10A is formed at the tip side thereof. It has been drilled. The pair of left and right bucket cylinder brackets 23 are joined to the outer surface 14A3 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 used in the present embodiment. The auxiliary welding member 24 is provided on the outer surface 14A3 of the rear thick upper plate 14A 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. Here, as shown in FIGS. 8 to 10, the auxiliary welding member 24 is formed as a flat plate having a substantially M shape in plan view as viewed from above. That is, the auxiliary welding member 24 as a whole is formed of a rectangular flat plate having a width dimension slightly smaller than the width dimension in the left and right directions of the rear thick upper plate 14A, and is located in the middle part in the left and right directions and is located at the front end 24A. And a pair of left and right groove portions 24D extending forward from the rear end portion 24C.

  The auxiliary welding member 24 is disposed on the outer surface 14A3 of the rear thick upper plate 14A in a state where the front portion side of each bucket cylinder bracket 23 is inserted into the pair of groove portions 24D. The outer peripheral edge) is fillet welded to the outer surface 14A3 of the rear thick upper plate 14A over the entire circumference. Accordingly, as shown in FIG. 10, the plate thickness 24t of the auxiliary welding member 24 is superimposed on the plate thickness 14At of the rear thick upper plate 14A, and the plate of the portion where the bucket cylinder bracket 23 is joined to the rear thick upper plate 14A. The thickness can be partially increased.

  Further, as shown in FIG. 5, the front end 24 </ b> A of the auxiliary welding member 24 is located at the position of the connecting pin 10 </ b> A that connects the bucket cylinder 10 shown in FIG. 1 of the bucket cylinder bracket 23, that is, the position of the pin insertion hole 23 </ b> A. The rear end 24C of the auxiliary welding member 24 is disposed further to the rear than the upper end 19A of the internal partition wall 19 joined to the inner surface 14A4 of the rear thick upper plate 14A. In this manner, the auxiliary welding member 24 is disposed so as to extend in the front and rear directions with the upper end portion 19A of the internal partition wall 19 interposed therebetween.

  On the other hand, as shown in FIGS. 11 and 12, a bracket-side weld bead 26 </ b> A that constitutes a weld bead 26 described later is formed at a joint portion between the outer surface 14 </ b> A <b> 3 of the rear thick upper plate 14 </ b> A and the bucket cylinder bracket 23. Therefore, in a state where the groove portion 24D of the auxiliary welding member 24 is inserted into the front portion side of the bucket cylinder bracket 23, a gap 25 is formed between the groove portion 24D of the auxiliary welding member 24 and the bucket cylinder bracket 23.

  In this state, a fillet weld is applied to the peripheral edge portion of the groove portion 24D provided in the auxiliary welding member 24 using, for example, a welding torch 100, thereby forming between the bucket cylinder bracket 23 and the rear thick upper plate 14A. A weld bead 26 is formed by integrating the bracket-side weld bead 26A and the auxiliary weld member-side weld bead 26B formed between the groove 24D of the auxiliary weld member 24 and the rear thick upper plate 14A. The bead 26 can embed a gap 25 formed between the groove portion 24 </ b> D of the auxiliary welding member 24 and the bucket cylinder bracket 23.

  Thereby, as shown in FIG. 10, each groove part 24D of the auxiliary welding member 24 and each bucket cylinder bracket 23 can be joined by the weld beads 26 that are smoothly continuous, and joined to the rear thick upper plate 14A. Each bucket cylinder bracket 23 thus made can be reinforced by the auxiliary welding member 24. Further, a concave notch 24B is provided at the front end 24A of the auxiliary welding member 24, and fillet welding is performed around the notch 24B, thereby reducing the welding length of the auxiliary welding member 24 to the rear thick upper plate 14A. The configuration can be secured large.

  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.

  A pair of left and right arm cylinder brackets 22 are joined to the outer surface of the thick rear plate 16 by welding. Further, a pair of left and right bucket cylinder brackets 23 are joined to the outer surface 14A3 of the rear thick upper plate 14A constituting the upper plate 14 by welding.

  Next, the auxiliary welding member 24 is placed on the outer surface 14A3 of the rear thick upper plate 14A so as to surround the bracket side weld bead 26A formed between the front side of each bucket cylinder bracket 23 and the rear thick upper plate 14A. Provide. That is, the auxiliary welding member 24 is disposed on the outer surface 14A3 of the rear thick upper plate 14A in a state where the front side of the bucket cylinder bracket 23 is inserted into each groove 24D of the auxiliary welding member 24. The outer peripheral edge is fillet welded to the outer surface 14A3 of the rear thick upper plate 14A over the entire circumference. Thus, as shown in FIG. 10, the plate thickness 14t of the auxiliary welding member 24 can be superimposed on the plate thickness 14At of the rear thick upper plate 14A, and the bucket cylinder bracket 23 of the rear thick upper plate 14A is joined. The plate thickness of the part can be partially increased.

  In this case, as shown in FIGS. 11 and 12, the bracket-side weld bead 26 </ b> A is formed at the joint between the outer surface 14 </ b> A <b> 3 of the rear thick upper plate 14 </ b> A and the bucket cylinder bracket 23. In a state where 24D is inserted into the front side of the bucket cylinder bracket 23, a gap 25 is formed between the groove 24D of the auxiliary welding member 24 and the bucket cylinder bracket 23.

  In this state, a fillet weld is applied to the peripheral edge portion of the groove portion 24D provided in the auxiliary welding member 24 using, for example, a welding torch 100, thereby forming between the bucket cylinder bracket 23 and the rear thick upper plate 14A. The welded bead 26 formed by integrating the bracket-side weld bead 26A and the auxiliary weld member-side weld bead 26B formed between the groove 24D of the auxiliary weld member 24 and the rear thick upper plate 14A is formed. be able to. Therefore, this weld bead 26 can embed a gap 25 formed between the groove 24D of the auxiliary welding member 24 and the bucket cylinder bracket 23. As shown in FIG. 24D and each bucket cylinder bracket 23 can be joined by a weld bead 26 that is smoothly continuous.

  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 bracket side formed on the outer surface 14A3 of the rear thick upper plate 14A constituting the upper plate 14 between the front side of the bucket cylinder bracket 23 and the rear thick upper plate 14A. An auxiliary welding member 24 is provided so as to surround the weld bead 26A (welding portion), and fillet welding is performed over the entire circumference between the outer peripheral edge portion of the auxiliary welding member 24 and the rear thick upper plate 14A. .

  Thus, as shown in FIG. 10, the plate thickness 14t of the auxiliary welding member 24 can be superimposed on the plate thickness 14At of the rear thick upper plate 14A, and the bucket cylinder bracket 23 of the rear thick upper plate 14A is joined. The plate thickness of the part can be partially increased. For this reason, it is possible to suppress the rear thick upper plate 14A and each bucket cylinder bracket 23 from being greatly deformed by a load acting on each bucket cylinder bracket 23, and to improve the durability of the entire arm 11.

  In addition, in the state where the groove portion 24D of the auxiliary welding member 24 is inserted into the front portion side of the bucket cylinder bracket 23, by performing fillet welding on the peripheral edge portion of the groove portion 24D provided in the auxiliary welding member 24, the bucket cylinder bracket 23 And the bracket-side weld bead 26A formed between the rear thick upper plate 14A and the auxiliary weld member-side weld bead 26B formed between the groove 24D of the auxiliary weld member 24 and the rear thick upper plate 14A. And integrated weld bead 26 can be formed. As a result, as shown in FIG. 10, the groove portions 24 </ b> D of the auxiliary welding member 24 and the bucket cylinder brackets 23 can be joined by the smoothly continuous weld beads 26.

  As a result, each bucket cylinder bracket 23 joined to the rear thick upper plate 14A can be reinforced by the auxiliary welding member 24, and without increasing the plate thickness of each bucket cylinder bracket 23, the rear thick upper plate 14A can be Since the joining strength of each bucket cylinder bracket 23 can be increased, the weight of the entire arm 11 can be reduced while ensuring the necessary strength.

  Further, since the auxiliary welding member 24 is provided with a notch portion 24B having a concave shape from the front end portion 24A toward the rear, by applying fillet welding around the notch portion 24B, the rear thick upper plate 14A A large welding length of the auxiliary welding member 24 can be secured, and the strength of the welded portion between the rear thick upper plate 14A and the bucket cylinder bracket 23 reinforced by the auxiliary welding member 24 can be increased.

  Further, since the internal partition wall 19 is provided between the boom connecting boss 18 and the inner surface 14A4 of the rear thick upper plate 14A, the inner partition wall 19 prevents the rear thick upper plate 14A from being deformed so as to sink into the inner surface 14A4 side. be able to. In this case, since the rear end portion 24C of the auxiliary welding member 24 extends to the rear side of the position of the upper end portion 19A of the internal partition wall 19, by joining the auxiliary welding member 24, the rear thick upper plate 14A The effect of increasing the plate thickness and the effect of supporting the rear thick upper plate 14A from the inner surface 14A4 side by the internal partition wall 19 can be obtained at the same time, and the strength of the rear thick upper plate 14A, each bucket cylinder bracket 23, and the auxiliary welding member 24 can be obtained. Can be further enhanced.

  In the above-described embodiment, the case where one M-shaped auxiliary welding member 24 having the notch portion 24B and the left and right groove portions 24D is used is illustrated. However, the present invention is not limited to this. For example, as in the modification shown in FIG. 13, two auxiliary welding members 27 are provided, one for each of the left and right bucket cylinder brackets 23. Also good. The auxiliary welding member 27 is formed of a rectangular flat plate extending in the front and rear directions, and the outer peripheral edge of the auxiliary welding member 27 is entirely inserted in a state where the bucket cylinder bracket 23 is inserted into one groove portion 27A extending in the front and rear directions. Fillet welded to the outer surface 14A3 of the rear thick upper plate 14A over the circumference.

  Moreover, in embodiment mentioned above, after joining the boom connection boss | hub 18, the bucket connection boss | hub 20, and the rear link connection boss | hub 21 to the left and right side plates 12 and 13 as an example of the procedure of assembling the arm 11, 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.

  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)
10 Bucket cylinder 10A Connecting pin 11 Arm 12 Left side plate 13 Right side plate 14 Upper plate 14A Rear thick upper plate 14A3 Outer surface 15 Lower plate 16 Thick rear plate (Rear plate)
18 Boom Connection Boss 19 Internal Bulkhead 19A Upper End 20 Bucket Connection Boss 23 Bucket Cylinder Bracket 24, 27 Auxiliary Welding Member 24A Front End 24B Notch 24C Rear End 25 Clearance 26 Weld Bead 26A Bracket Side Weld Bead 26B Auxiliary Weld Member Side Weld bead

Claims (4)

Left and right side plates, upper plates joined to the upper ends of the left and right side plates by welding, lower plates 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,
In the construction machine arm comprising a pair of left and right bucket cylinder brackets joined to the outer surface of the rear end side of the upper plate by welding,
On the outer surface of the rear side of the upper plate, a flat auxiliary welding member is provided so as to surround the welded portion between the left and right pair of bucket cylinder brackets and the upper plate,
A construction machine arm characterized in that fillet welding is performed around the auxiliary welding member. A reinforcing internal partition is provided between the boom connecting boss and a position on the inner surface side of the upper plate and on the front side of the position of the connecting pin provided on the bucket cylinder bracket,
The construction machine arm according to claim 1, wherein a rear end of the auxiliary welding member extends to a rear side from an upper end position of the internal partition wall.   The gap formed between the bucket cylinder bracket and the auxiliary welding member on the outer surface of the upper plate is configured to be buried by the welding bead of the bucket cylinder bracket and the welding bead of the auxiliary welding member. The construction machine arm according to 2. The auxiliary welding member is formed in an M shape in plan view,
4. The construction machine arm according to claim 1, wherein the M-shaped auxiliary welding member is provided with a notch that is recessed in a rearward shape on the front side.

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