JP5595974B2 - 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, the left and right side plates, the upper plate, and the lower plate constituting the arm are usually formed using a single plate material such as a steel plate material having a uniform plate thickness (Patent Document 1).

  On the other hand, a single plate is formed by welding a plurality of flat plates with different plate thicknesses by welding, and each side plate of the arm, an upper plate, using a plate material formed by bonding a plurality of flat plates with different plate thicknesses, A method of forming a lower plate is known (Patent Document 2).

JP 2003-261156 A JP 2001-115477 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 arm according to Patent Document 1 described above, the upper plate and the lower plate are usually formed 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, in Patent Document 2 described above, although the weight of the arm can be reduced, two flat plates having different plate thicknesses are formed when forming a plate material that is a material of a side plate, an upper plate, and a lower plate constituting the arm. These two flat plates need to be butt-welded in a state in which the backing material is disposed on the back side. For this reason, in order to ensure the reliability (durability) of a welding part, the thickness of two flat plates is needed to some extent, and there exists a problem that it cannot fully reduce in weight. Moreover, there exists a problem that workability | operativity at the time of butt-welding two flat plates from which plate | board thickness differs is reduced.

  The present invention has been made in view of the above-mentioned problems of the prior art, and can reduce the overall weight while ensuring the necessary strength, and can improve the workability of welding work. The purpose is to provide an arm.

  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. This is applied to a construction machine arm provided with a bucket connecting boss joined by welding to the front ends of the side plate, the upper plate and the lower plate.

The invention of claim 1 is characterized in that the bucket connecting boss is provided with flanges located on both left and right sides of the cylindrical boss portion and extending toward the left and right side plates, and the left and right At the front end of the side plate, a groove extending upward and downward is provided by notching without a root face, and at the rear end of the left and right flanges of the bucket connecting boss , by notching without a root face A groove extending in the upward and downward directions is provided, and the groove of the left and right side plates and the groove of the left and right ribs are abutted to form a V-shaped opening having no root face and no gap. A point is formed, and the left and right side plates and the left and right flanges are melted at the position of the V-shaped groove to perform welding and complete welding.

According to a second aspect of the invention, the left and right side plates are made of a thick plate material located on the rear side and made of a thick plate material, and made of a thin plate material located on the front side of the rear thick side plate. formed by two members of the front thin plate, on the rear end of the front end and the front thin plate of the rear thick plate is on by the lack root face without switching, respectively a groove extending in the downward direction, the rear By abutting the groove of the thick side plate and the groove of the front thin side plate, a V-shaped groove having no root face and no gap is formed, and at the position of the V-shaped groove, the rear thick side plate and the In this configuration, the front thin side plate is melted to perform welding and complete welding.

  The invention according to claim 3 is characterized in that the upper plate is a rear thick upper plate made of a thick plate material located on the rear side, and a front thin plate made of a thin plate material located on the front side of the rear thick upper plate. Formed by two members with the upper plate, the front end of the rear thick upper plate and the rear end of the front thin upper plate are each provided with a groove extending left and right by notching without a root face, By matching the groove of the rear thick upper plate and the groove of the front thin upper plate, a V-shaped groove having no root face and no gap is formed, and the rear thickness is formed at the position of the V-shaped groove. The upper plate and the front thin upper plate are melted to perform welding and complete welding.

  According to a fourth aspect of the present invention, the lower plate is a rear thick lower plate that is located on the rear side and made of a thick plate material, and a front plate that is located on the front side of the rear thick lower plate and made of a thin plate material. Formed by two members with a thin lower plate, the front end of the rear thin lower plate and the rear end of the front thin lower plate are each provided with a groove extending left and right by notching without a root face, By abutting the groove of the rear thick lower plate and the groove of the front thin lower plate, a V-shaped groove having no root face and no gap is formed, and the groove is formed at the position of the V-shaped groove. The present invention has a configuration in which the rear thick lower plate and the front thin lower plate are melted to perform welding and complete welding.

  The invention of claim 5 is that the groove angle of the V-shaped groove is set to a range of 43 degrees or more and 90 degrees or less.

According to the invention of claim 1, by combining impact and groove provided on the rear end of the flange portion constituting the groove and bucket connecting bosses provided at the front end of the side plate, no root face, and a gap No V-shaped groove can be formed. Therefore, by performing butt welding at the position of the V-shaped groove, it is possible to perform complete welding in which the front end of the side plate and the flange portion of the bucket connecting boss are melted over the entire plate thickness , and the side plate and the bucket are connected. Bonding strength with the boss can be increased. Moreover, since it is not necessary to arrange a backing material on the back side of the V-shaped groove, workability when performing butt welding between the side plate and the flange portion of the bucket connecting boss can be improved.

According to the invention of claim 2, the required strength can be secured by the rear thick side plate on the rear side of the arm, and the weight can be reduced by the front thin side plate on the front side of the arm. Compared with the case where the side plate is configured using a single plate member, the weight of the entire arm can be reduced while maintaining the necessary strength. In this case, the groove provided at the front end of the rear thick side plate and the groove provided at the rear end of the front thin side plate are abutted to form a V-shaped groove having no root face and no gap. it can. Therefore, when performing butt welding at the position of the V shape groove, and the rear thick plate before the thin plate is Ru can perform complete welding that dissolved over the entire plate thickness. As a result, the bonding strength between the rear thick side plate and the front thin side plate can be increased, and the strength and durability of the entire arm can be increased.
Moreover, a backing material is formed on the back side of the V-shaped groove by forming a V-shaped groove having no root face and no gap at the abutting portion between the groove of the rear thick side plate and the groove of the front thin side plate. Can be completely welded to the butted portion of the rear thick side plate and the front thin side plate. Therefore, workability when performing butt welding between the rear thick side plate and the front thin side plate can be improved.

  According to the invention of claim 3, since the required strength can be ensured by the rear thick upper plate on the rear side of the arm and the front thin side plate can reduce the weight on the front side of the arm. The weight of the entire arm can be reduced while maintaining. Further, by forming a groove provided at the front end of the rear thick upper plate and a groove provided at the rear end of the front thin upper plate, a V-shaped groove having no root face and no gap is formed. Can do. Therefore, by performing butt welding at the position of the V-shaped groove, it is possible to perform complete welding in which the rear thick upper plate and the front thin upper plate are melted over the entire plate thickness. Bonding strength with the front thin plate can be increased. Moreover, since it is not necessary to arrange a backing material on the back side of the V-shaped groove, it is possible to improve workability when performing butt welding between the rear thick upper plate and the front thin upper plate.

  According to the invention of claim 4, since the required strength can be ensured by the rear thick lower plate on the rear side of the arm and the weight can be reduced by the front thin lower plate on the front side of the arm. The weight of the entire arm can be reduced while maintaining. Further, by forming a groove provided at the front end of the rear thick lower plate and a groove provided at the rear end of the front thin lower plate, a V-shaped groove having no root face and no gap is formed. Can do. Accordingly, by performing butt welding at the position of the V-shaped groove, complete welding in which the rear thick lower plate and the front thin lower plate are melted over the entire plate thickness can be performed. Bonding strength with the front thin lower plate can be increased. Moreover, since it is not necessary to arrange a backing material on the back side of the V-shaped groove, it is possible to improve workability when performing butt welding between the rear thick lower plate and the front thin lower plate.

  According to the invention of claim 5, the groove angle of the V-shaped groove formed by the groove of one of the two members to be butt welded and the groove of the other member is set to 43 degrees or more. Thus, for example, when two members are butt-welded using means such as arc welding, the heat of the arc is sufficiently supplied to the groove of one of the members and the groove of the other member The two members can be melted over the entire plate thickness. In addition, by setting the groove angle of the V-shaped groove at the abutting portion of the two members to 90 degrees or less, the V-shaped groove can be filled with molten metal without excess or deficiency, and the two members can be smoothly connected. A weld bead can be formed.

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 sectional drawing which looked at the junction part of a back thick side plate and a front thin side plate from the arrow IX-IX direction in FIG. It is sectional drawing which shows the groove | channel of a rear thick side plate, and the groove | channel of a front thin side plate. It is sectional drawing which shows the V-shaped groove | channel formed by the groove | channel of the back thick side plate, and the groove | channel of the front thin side plate. It is sectional drawing which shows the state which carries out butt welding of a back thick side board and a front thin side board in the position of a V-shaped groove. It is sectional drawing which looked at the junction part of a front thin side plate and a bucket connection boss | hub from the arrow XIII-XIII direction in FIG. It is sectional drawing which shows the groove | channel of the groove | channel of a front thin side plate, and a bucket connection boss | hub. It is sectional drawing which shows the V-shaped groove | channel formed with the groove | channel of the front thin side plate, and the groove | channel of the collar part of a bucket connection boss | hub. It is sectional drawing which shows the state which butt-welds a front thin side plate and the collar part of a bucket connection boss | hub at the position of a V-shaped groove | channel. It is sectional drawing which shows the junction part of a back thick upper board and a front thin upper board. It is sectional drawing which shows the groove | channel of a rear thick upper board, and the groove | channel of a front thin upper board. It is sectional drawing which shows the V-shaped groove | channel formed by the groove | channel of the back thick upper board, and the groove | channel of the front thin upper board. It is sectional drawing which shows the state which carries out butt welding of a back thick upper board and a front thin upper board in the position of a V-shaped groove | channel. It is sectional drawing which shows the junction part of a back thickness lower board and a front thin lower board. It is sectional drawing which shows the groove | channel of a rear thickness lower board, and the groove | channel of a front thin lower board. It is sectional drawing which shows the V-shaped groove | channel formed by the groove | channel of the back thin lower board, and the groove | channel of the front thin lower board. It is sectional drawing which shows the state which carries out butt welding of a back thickness lower board and a front thin lower board in the position of a V-shaped groove.

  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. Secured. 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. Furthermore, a groove 12A6 described later is provided in the front thin plate joint 12A4.

  Reference numeral 12A6 denotes a groove provided at the front end of the rear thick side plate 12A. The groove 12A6 is abutted with a rear groove 12B6 of the front thin side plate 12B described later. Here, as shown in FIG. 9 to FIG. 12, the groove 12A6 is formed by inclining and cutting the end edge portion of the front thin side plate joint portion 12A4 constituting the rear thick side plate 12A toward the outer surface side. Has been. The groove 12A6 is formed as a uniform inclined surface having no root face, and is provided over the entire area of the front thin side plate joint portion 12A4.

  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. Further, a rear groove 12B6, which will be described later, is provided in the rear thick side plate joint 12B4 which is the rear end of the front thin side plate 12B, and a front opening which will be described later is provided in the bucket connecting boss joint 12B3 which is the front end of the front thin side plate 12B. A tip 12B7 is provided.

  Reference numeral 12B6 denotes a rear groove provided at the rear end of the front thin side plate 12B. The rear groove 12B6 is abutted against the groove 12A6 of the rear thick side plate 12A. Here, as shown in FIG. 9 to FIG. 12, the rear groove 12B6 is cut out by inclining the edge portion of the rear thick side plate joining portion 12B4 constituting the front thin side plate 12B toward the outer surface side. It is formed by. The groove 12B6 is formed as a uniform inclined surface having no root face, and is provided over the entire area of the rear thick side plate joint 12B4.

  Reference numeral 12B7 denotes a front groove provided at the front end of the front thin side plate 12B, and the front groove 12B7 is abutted against a groove 20B1 provided in a port side 20B of the bucket connecting boss 20 described later. . Here, as shown in FIGS. 13 to 16, the front groove 12B7 is formed by inclining the edge of the bucket connecting boss joint 12B3 constituting the front thin side plate 12B toward the inner surface side. Is formed. The groove 12B7 is formed as a uniform inclined surface having no root face, and is provided over the entire region of the bucket connecting boss joint 12B3.

  On the other hand, as shown in FIGS. 6 and 9, if the thickness of the rear thick side plate 12A constituting the left side plate 12 is 12 At and the thickness of the front thin side plate 12 B is 12 Bt, the thickness of the plate 12 At and the thickness 12 Bt The relationship is set as shown in Equation 1 below.

  Further, as shown in FIG. 11, the inner surface of the rear thick side plate 12A and the front thin side plate are formed by abutting the groove 12A6 of the rear thick side plate 12A and the rear groove 12B6 of the front thin side plate 12B without a gap (gap). The same plane with no step is formed with the inner surface of 12B. On the other hand, the outer surface of the rear thick side plate 12A and the outer surface of the front thin side plate 12B form a step according to the plate thickness difference, and a V-shaped groove 12C having no root face and no gap is formed in this step portion. . In this case, when the groove angle of the V-shaped groove 12C is θ, the groove angle θ is set in the range of the following formula 2.

  Then, for example, as shown in FIG. 12, by performing butt welding using the welding torch 100 or the like at the position of the V-shaped groove 12C, the front thin side plate joint 12A4 of the rear thick side plate 12A and the rear thin side plate 12B The thick side plate joining portion 12B4 is joined in a completely welded state, and the left side plate 12 including the rear thick side plate 12A and the front thin side plate 12B is formed.

  Here, the opening width of the V-shaped groove 12 </ b> C is determined according to the outer diameter of the welding torch 100. Further, the groove angle θ of the V-shaped groove 12C is determined based on the outer diameter size of the welding torch 100, the plate thickness 12At of the rear thick side plate 12A, the plate thickness 12Bt of the front thin side plate 12B, and the required amount of weld bead. It is what is done. In this case, if the groove angle θ is too small, the rear thick side plate 12A and the front thin side plate 12B are not sufficiently melted, and if the groove angle θ is too large, the amount of beads to be used increases and welding workability is improved. In order to decrease, it is desirable to set the groove angle θ within the range of the above formula 2.

  Next, 13 indicates 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, a boom connecting boss joint 13A5 that is cut out in an arc shape is provided at the corner where the lower plate joint 13A2 and the rear plate joint 13A3 intersect, and the front thin side plate joint 13A4 has an opening described later. A tip 13A6 is provided.

  Reference numeral 13A6 denotes a groove provided at the front end of the rear thick side plate 13A, and the groove 13A6 is abutted with a rear groove 13B6 of the front thin side plate 13B described later. Here, as shown in FIGS. 9 to 12, the groove 13A6 is formed by inclining and notching the end edge portion of the front thin side plate joint portion 13A4 constituting the rear thick side plate 13A toward the outer surface side. Has been. The groove 13A6 is formed as a uniform inclined surface having no root face, and is provided over the entire area of the front thin side plate joint portion 13A4.

  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. Further, a rear groove 13B6, which will be described later, is provided in the rear thick side plate joint 13B4 that is the rear end of the front thin side plate 13B, and a front opening that will be described later is provided in the bucket connection boss joint 13B3 that is the front end of the front thin side plate 13B. A tip 13B7 is provided.

  Reference numeral 13B6 denotes a rear groove provided at the rear end of the front thin side plate 13B, and the rear groove 13B6 is abutted against the groove 13A6 of the rear thick side plate 13A. Here, as shown in FIG. 9 to FIG. 12, the rear groove 13B6 is cut out by inclining the edge portion of the rear thick side plate joint portion 13B4 constituting the front thin side plate 13B toward the outer surface side. It is formed by. The groove 13B6 is formed as a uniform inclined surface having no root face, and is provided over the entire area of the rear thick side plate joint portion 13B4.

  13B7 indicates a front groove provided at the front end of the front thin side plate 13B, and the front groove 13B7 is abutted against a groove 20C1 provided in a starboard portion 20C of the bucket connecting boss 20 described later. . Here, as shown in FIGS. 13 to 16, the front groove 13B7 is formed by inclining the end edge portion of the bucket connecting boss joint portion 13B3 constituting the front thin side plate 13B toward the inner surface side. Is formed. The groove 13B7 is formed as a uniform inclined surface having no root face, and is provided over the entire region of the bucket connecting boss joint 13B3.

  On the other hand, as shown in FIGS. 6 and 9, if the thickness of the rear thick side plate 13A constituting the right side plate 13 is 13 At and the thickness of the front thin side plate 13 B is 13 Bt, the thickness 13 At and the thickness 13 Bt are The relationship is set as shown in Equation 3 below.

  Further, as shown in FIG. 11, the inner surface of the rear thick side plate 13A and the front thin side plate are formed by abutting the groove 13A6 of the rear thick side plate 13A and the rear groove 13B6 of the front thin side plate 13B without gaps. The same plane with no step is formed with the inner surface of 13B. On the other hand, the outer surface of the rear thick side plate 13A and the outer surface of the front thin side plate 13B form a step according to the plate thickness difference, and a V-shaped groove 13C having no root face and no gap is formed in this step portion. . In this case, when the groove angle of the V-shaped groove 13C is θ, the groove angle θ is set in the range of the above formula 2.

  Then, for example, as shown in FIG. 12, by performing butt welding using a welding torch 100 or the like at the position of the V-shaped groove 13C, the front thin side plate joint portion 13A4 of the rear thick side plate 13A and the rear thin side plate 13B are The thick side plate joint portion 13B4 is joined in a completely welded state, and the right side plate 13 including the rear thick side plate 13A and the front thin side plate 13B is formed.

  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. A thin plate joining portion 14A2 is formed, and a groove 14A3 described later is provided in the front thin plate joining portion 14A2.

  Reference numeral 14A3 denotes a groove provided at the front end of the rear thick upper plate 14A, and the groove 14A3 abuts a groove 14B3 of the front thin upper plate 14B described later. Here, as shown in FIGS. 17 to 20, the groove 14A3 is cut out by inclining the edge of the front thin upper plate joint 14A2 constituting the rear thick upper plate 14A toward the outer surface side. It is formed by. The groove 14A3 is formed as a uniform inclined surface having no root face, and is provided over the entire area of the front thin upper plate joint portion 14A2.

  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. Further, a groove 14B3 described later is provided in the rear thick upper plate joint 14B1 which is the rear end of the front thin upper plate 14B.

  Reference numeral 14B3 denotes a groove provided at the rear end of the front thin upper plate 14B. The groove 14B3 is abutted with the groove 14A3 of the rear thick upper plate 14A. Here, as shown in FIGS. 17 to 20, the groove 14B3 is cut out by inclining the edge of the rear thick upper plate joint 14B1 constituting the front thin upper plate 14B toward the outer surface side. It is formed by. The groove 14B3 is formed as a uniform inclined surface having no root face, and is provided over the entire area of the rear thick upper plate joint 14B1.

  On the other hand, as shown in FIGS. 5 and 17, assuming that the thickness of the rear thick upper plate 14A constituting the upper plate 14 is 14 At and the thickness of the front thin upper plate 14 B is 14 Bt, the plate thickness 14 At and the plate thickness 14 Bt Is set as shown in Equation 4 below.

  Further, as shown in FIG. 19, the groove 14A3 of the rear thick upper plate 14A and the groove 14B3 of the front thin upper plate 14B are abutted without a gap (gap), so that the inner surface of the rear thick upper plate 14A and the front thin The same plane with no step is formed with the inner surface of the upper plate 14B. On the other hand, the outer surface of the rear thick upper plate 14A and the outer surface of the front thin upper plate 14B form a step corresponding to the plate thickness difference, and a V-shaped groove 14C having no root face and no gap is formed in this step portion. Is done. In this case, when the groove angle of the V-shaped groove 14C is θ, the groove angle θ is set in the range of the above formula 2.

  Then, for example, as shown in FIG. 20, by performing butt welding using a welding torch 100 or the like at the position of the V-shaped groove 14C, the front thin upper plate joining portion 14A2 of the rear thick upper plate 14A and the front thin upper plate The rear thick upper plate joint 14B1 of 14B is joined in a completely welded state, and the upper plate 14 composed of the rear thick upper plate 14A and the front thin upper plate 14B is formed.

  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. The front thin lower plate bonding portion 15A2 is provided, and a groove 15A3 described later is provided in the front thin lower plate bonding portion 15A2.

  Reference numeral 15A3 denotes a groove provided at the front end of the rear thick lower plate 15A, and the groove 15A3 abuts a groove 15B3 of the front thin lower plate 15B described later. Here, as shown in FIGS. 21 to 24, the groove 15A3 is cut out by inclining the edge portion of the front thin lower plate joining portion 15A2 constituting the rear thick lower plate 15A toward the outer surface side. It is formed by. The groove 15A3 is formed as a uniform inclined surface having no root face, and is provided over the entire area of the front thin lower plate joint portion 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. Furthermore, a groove 15B3 described later is provided in the rear thick lower plate joint 15B1 which is the rear end of the front thin lower plate 15B.

  Reference numeral 15B3 denotes a groove provided at the rear end of the front thin lower plate 15B, and the groove 15B3 is abutted against the groove 15A3 of the rear thick lower plate 15A. Here, as shown in FIGS. 21 to 24, the groove 15B3 is cut out by inclining the edge of the rear thick lower plate joint 15B1 constituting the front thin lower plate 15B toward the outer surface side. It is formed by. The groove 15B3 is formed as a uniform inclined surface having no root face, and is provided over the entire area of the rear thickness lower plate joint 15B1.

  On the other hand, as shown in FIG. 5 and FIG. 21, 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 Is set as shown in Equation 5 below.

  Further, as shown in FIG. 23, the groove 15A3 of the rear thick lower plate 15A and the groove 15B3 of the front thin lower plate 15B are abutted with no gap, so that the inner surface of the rear thick lower plate 15A and the front thin The same plane with no step is formed with the inner surface of the lower plate 15B. On the other hand, the outer surface of the rear thin lower plate 15A and the outer surface of the front thin lower plate 15B form a step corresponding to the plate thickness difference, and a V-shaped groove 15C having no root face and no gap is formed in this step portion. Is done. In this case, when the groove angle of the V-shaped groove 15C is θ, the groove angle θ is set in the range of the above formula 2.

  Then, for example, as shown in FIG. 24, butt welding is performed using a welding torch 100 or the like at the position of the V-shaped groove 15C, so that the front thin lower plate joint 15A2 of the rear thick lower plate 15A and the front thin lower plate The rear thick lower plate joining portion 15B1 of 15B is joined in a completely welded state, and the lower plate 15 including the rear thick lower plate 15A and the front thin lower plate 15B is formed.

  Next, 16 indicates a thick rear plate as a 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 has a longitudinal center. The part is bent in 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 lower thickness lower plate 15A constituting the lower plate 15 are equal to or greater than those, and are set as shown in the following formula 6.

  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, 13 and the upper plate are welded between the rear plate joining portion 14A1 of the rear thick upper plate 14A constituting the upper plate 14 and the thick rear plate 16, respectively. A thick rear plate 16 is firmly joined to the rear end side of the plate 14.

  Here, as shown in FIGS. 4 and 5, when looking at the junction 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> D of this junction is the rear of the upper plate 14. It joins in the position of the middle part of 14 A of thick upper boards, and the lower end part 12E of a joined part is joined in the position of the front part side of 15 A of back thickness lower boards of the lower board 15. On the other hand, as shown in FIG. 2, 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 13D of this joint portion is the rear thick upper plate 14A of the upper plate 14. The lower end portion 13E of the joined portion is joined at a position on the front side of the rear thick 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.

  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 plate-shaped port portions 20B and starboard portions 20C provided at both left and right ends of the cylindrical boss portion 20A. It is comprised by. Further, a groove 20B1 described later is provided at the rear end of the port side 20B, and a groove 20C1 described later is provided at the rear end of the starboard part 20C.

  Reference numeral 20B1 denotes a groove provided at the rear end of the left flange portion 20B constituting the bucket connecting boss 20, and the groove 20B1 is abutted against the front groove 12B7 provided on the front thin side plate 12B of the left side plate 12. Is. Here, as shown in FIGS. 13 to 16, the groove 20B1 is formed by inclining the rear end edge portion of the port portion 20B toward the inner surface side and cutting it out. The groove 20B1 is formed as a uniform inclined surface having no root face, and is provided over the entire rear edge of the port part 20B.

  In this case, the port portion 20B has a thickness substantially equal to the plate thickness 12Bt of the front thin side plate 12B. As shown in FIG. 15, the front groove 12B7 of the front thin side plate 12B and the port portion 20B By abutting the groove 20B1 without a gap (gap), the outer surface of the front thin side plate 12B and the outer surface of the port side 20B form the same plane with no step. On the other hand, a V-shaped groove 20D having no root face and no gap is formed on the inner surface side of the front thin side plate 12B and the port part 20B. In this case, when the groove angle of the V-shaped groove 20D is θ, the groove angle θ is set in the range of the above formula 2.

  Then, for example, as shown in FIG. 16, by performing butt welding using a welding torch 100 or the like at the position of the V-shaped groove 20D, the bucket connection boss joint 12B3 of the front thin side plate 12B and the left of the bucket connection boss 20 are left. The flange portion 20B is joined in a completely welded state.

  On the other hand, 20C1 indicates a groove provided at the rear end of the starboard portion 20C constituting the bucket connecting boss 20, and the groove 20C1 includes a front groove 13B7 provided on the front thin side plate 13B of the right side plate 13. It is to be abutted. Here, the groove 20C1 is formed by inclining and notching the rear end edge of the starboard portion 20C toward the inner surface. The groove 20C1 is formed as a uniform inclined surface having no root face, and is provided over the entire rear end edge of the starboard portion 20C.

  In this case, the starboard portion 20C has a plate thickness that is substantially equal to the plate thickness 13Bt of the front thin side plate 13B, and a gap (between the front groove 13B7 of the front thin side plate 13B and the groove 20C1 of the starboard portion 20C). By abutting without a gap), the outer surface of the front thin side plate 13B and the outer surface of the starboard portion 20C form the same plane with no step. On the other hand, a V-shaped groove 20E having no root face and no gap is formed on the inner surfaces of the front thin side plate 13B and the starboard portion 20C. In this case, when the groove angle of the V-shaped groove 20E is θ, the groove angle θ is set in the range of the above formula 2.

  Then, by performing butt welding using the welding torch 100 or the like at the position of the V-shaped groove 20E, the bucket connecting boss joint 13B3 of the front thin side plate 13B and the starboard portion 20C of the bucket connecting boss 20 are completely welded. It is joined in a state.

  Further, the cylindrical boss portion 20A of the bucket connection boss 20 includes a bucket connection boss joint portion 14B2 of the front thin upper plate 14B constituting the upper plate 14 and a bucket connection boss joint portion of the front thin lower plate 15B constituting the lower plate 15. It is joined to 15B2 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, as shown in FIGS. 10 and 11, a rear thick side plate 12A and a front thin side plate 12B constituting the left side plate 12 are prepared, and a groove 12A6 of the rear thick side plate 12A and a rear groove 12B6 of the front thin side plate 12B are prepared. And match. At this time, as shown in FIG. 12, a V-shaped groove 12C is formed between the respective grooves 12A6 and 12B6. Therefore, at the position of the V-shaped groove 12C, for example, butt welding is performed using means such as arc welding. I do. In this case, since the V-shaped groove 12C has no root face and no gap, the arc from the welding torch 100 can be supplied over the entire surface of each groove 12A6, 12B6. As a result, complete welding in which the rear thick side plate 12A and the front thin side plate 12B are melted over the entire plate thickness can be performed.

  Moreover, since the groove angle θ of the V-shaped groove 12C is set in the range of 43 degrees or more and 90 degrees or less, the heat of the arc can be sufficiently supplied to each of the grooves 12A6 and 12B6, and The V-shaped groove 12C can be filled with molten metal without excess and deficiency, and as shown in FIG. 9, a smoothly continuous weld bead 12F can be formed between the rear thick side plate 12A and the front thin side plate 12B. it can. As a result, the left side plate 12 in which the rear thick side plate 12A and the front thin side plate 12B are firmly joined can be formed without arranging a backing material or the like on the back side of the V-shaped groove 12C.

  On the other hand, similarly, the groove 13A6 of the rear thick side plate 13A constituting the right side plate 13 and the rear groove 13B6 of the front thin side plate 13B are abutted to form a V-shaped groove 13C, and this V-shaped groove is formed. Butt welding is performed at 13C using means such as arc welding. As a result, the rear thick side plate 13A and the front thin side plate 13B can be completely welded over the entire thickness of the plate, and the weld bead is smoothly continuous between the rear thick side plate 13A and the front thin side plate 13B. 13F can be formed. As a result, the right side plate 13 in which the rear thick side plate 13A and the front thin side plate 13B are firmly joined can be formed without arranging a backing material or the like on the back side of the V-shaped groove 13C.

  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.

  Next, as shown in FIGS. 14 and 15, the front groove 12 </ b> B <b> 7 of the front thin side plate 12 </ b> B constituting the left side plate 12 and the groove 20 </ b> B <b> 1 of the left flange 20 </ b> B constituting the bucket connecting boss 20 are brought into contact with each other. As a result, a V-shaped groove 20D is formed between the grooves 12B7 and 20B1, and as shown in FIG. 16, butt welding is performed at the position of the V-shaped groove 20D using means such as arc welding. . In this case, the V-shaped groove 20D has no root face, no gap, and the groove angle θ is set in a range of 43 degrees to 90 degrees.

  For this reason, an arc from the welding torch 100 is supplied over the entire surface of each of the grooves 12B7 and 20B1, and complete welding is performed in which the front thin side plate 12B and the port portion 20B are melted over the entire plate thickness. it can. As a result, as shown in FIG. 13, a smoothly continuous weld bead 20F can be formed between the front thin side plate 12B and the port part 20B, and a backing material or the like is provided on the back side of the V-shaped groove 20D. Without arranging, the front thin side plate 12B and the port side 20B can be firmly joined.

  On the other hand, similarly, the front groove 13B7 of the front thin side plate 13B constituting the right side plate 13 and the groove 20C1 of the starboard portion 20C constituting the bucket connecting boss 20 are abutted to form a V-shaped groove 20E. Then, butt welding is performed at the position of the V-shaped groove 20E using means such as arc welding. As a result, the front thin side plate 13B and the starboard portion 20C can be completely welded over the entire thickness of the plate, and the weld bead is smoothly continuous between the front thin side plate 13B and the starboard portion 20C. Since 20G can be formed, the front thin side plate 13B and the starboard portion 20C can be firmly joined without arranging a backing material or the like on the back side of the V-shaped groove 20E.

  Next, as shown in FIGS. 18 and 19, the groove 14A3 of the rear thick upper plate 14A constituting the upper plate 14 and the groove 14B3 of the front thin upper plate 14B are abutted to form a V-shaped groove 14C. Then, as shown in FIG. 20, butt welding is performed at the position of the V-shaped groove 14C using means such as arc welding. In this case, since the V-shaped groove 14C has no root face, no gap, and the groove angle θ is set in a range of 43 degrees or more and 90 degrees or less, an arc from the welding torch 100 is applied to each groove. 14A3 and 14B3 can be supplied over the entire surface. As a result, the rear thick upper plate 14A and the front thin upper plate 14B can be completely welded over the entire thickness of the plate, and as shown in FIG. 17, the rear thick upper plate 14A and the front thin upper plate By forming a weld bead 14D smoothly continuous with 14B, the rear thick upper plate 14A and the front thin upper plate 14B are strong without placing a backing material or the like on the back side of the V-shaped groove 14C. The upper plate 14 joined to the substrate can be formed.

  Also, as shown in FIGS. 22 and 23, a groove 15A3 of the rear thick lower plate 15A constituting the lower plate 15 and a groove 15B3 of the front thin lower plate 15B are abutted to form a V-shaped groove 15C. 24, butt welding is performed at the position of the V-shaped groove 15C using means such as arc welding. In this case, the V-shaped groove 15C has no root face, no gap, and the groove angle θ is set in a range of 43 degrees or more and 90 degrees or less. Therefore, an arc from the welding torch 100 is applied to each groove. It can be supplied over the entire surface of 15A3 and 15B3. As a result, the rear thick lower plate 15A and the front thin lower plate 15B can be completely welded with each other over the entire plate thickness, and as shown in FIG. 12, the rear thick lower plate 15A and the front thin lower plate By forming a smoothly continuous weld bead 15D with 15B, the rear thick lower plate 15A and the front thin lower plate 15B are strong without placing a backing material or the like on the back side of the V-shaped groove 15C. The lower plate 15 joined to the substrate 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.

  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 groove 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 groove 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.

  Here, according to the present embodiment, the left side plate 12 constituting the arm 11 is formed by two members of the rear thick side plate 12A and the front thin side plate 12B, and the right side plate 13 is formed by the rear thick side plate 13A and the front thin side plate 13B. And two members. Accordingly, the necessary strength is ensured by the left and right rear thick side plates 12A and 13A on the rear side of the arm 11, and the weight is reduced by the left and right front thin side plates 12B and 13B on the front side of the arm 11. Therefore, the weight of the entire arm 11 can be reduced while maintaining the required strength as compared with the case where the side plate is formed using a single plate material having a uniform plate thickness, for example.

  In this case, the groove 12A6 provided in the rear thick side plate 12A constituting the left side plate 12 and the rear groove 12B6 provided in the front thin side plate 12B are brought into contact with each other, whereby the rear thick side plate 12A and the front thin side plate 12B are brought together. It is possible to form a V-shaped groove 12C having no root face at the butt portion and no gap. Also, the rear thick side plate 13A and the front thin side plate 13B are abutted by abutting the groove 13A6 provided on the rear thick side plate 13A constituting the right side plate 13 with the rear side groove 13B6 provided on the front thin side plate 13B. It is possible to form a V-shaped groove 13C having no root face in the portion and no gap.

  Accordingly, when the butt welding of the rear thick side plate 12A and the front thin side plate 12B of the left side plate 12 is performed at the position of the V-shaped groove 12C, the rear thick side plate 12A and the front thin side plate 12B cover the entire plate thickness. Can be completely welded. Accordingly, since the root face is not provided, the thickness of the rear thick side plate 12A and the front thin side plate 12B can be reduced, while ensuring the welding strength of the joint portion between the rear thick side plate 12A and the front thin side plate 12B, The left side plate 12 can be reduced in weight.

  Similarly, when performing butt welding of the rear thick side plate 13A and the front thin side plate 13B of the right side plate 13 at the position of the V-shaped groove 13C, the rear thick side plate 13A and the front thin side plate 13B cover the entire plate thickness. Can be completely welded. Therefore, since the root face is not provided, the thickness of the rear thick side plate 13A and the front thin side plate 13B can be reduced, while ensuring the welding strength of the joint portion between the rear thick side plate 13A and the front thin side plate 13B, The right side plate 13 can be reduced in weight.

  Further, the front groove 12B7 of the front thin side plate 12B constituting the left side plate 12 and the groove 20B1 of the port side 20B constituting the bucket connecting boss 20 are abutted, so that there is no root face between the two, and A V-shaped groove 20D having no gap can be formed. Further, the front side groove 13B7 of the front thin side plate 13B constituting the right side plate 13 and the groove 20C1 of the starboard portion 20C constituting the bucket connecting boss 20 are brought into contact with each other, and there is no root face between the two. A V-shaped groove 20E having no gap can be formed.

  Thereby, complete welding in which the front thin side plate 12B and the port side portion 20B have melted over the entire plate thickness at the position of the V-shaped groove 20D can be performed. Similarly, complete welding in which the front thin side plate 13B and the starboard portion 20C are melted over the entire plate thickness at the position of the V-shaped groove 20E can be performed.

  On the other hand, the groove 14A3 provided on the rear thick upper plate 14A constituting the upper plate 14 and the groove 14B3 provided on the front thin upper plate 14B are brought into contact with each other, whereby the rear thick upper plate 14A and the front thin upper plate 14B Thus, a V-shaped groove 14C having no root face and no gap can be formed. Further, the groove 15A3 provided in the rear thick lower plate 15A constituting the lower plate 15 and the groove 15B3 provided in the front thin lower plate 15B are brought into contact with each other, whereby the rear thick lower plate 15A and the front thin lower plate 15B Thus, a V-shaped groove 15C having no root face and no gap can be formed.

  As a result, when the butt welding of the rear thick upper plate 14A and the front thin upper plate 14B is performed at the position of the V-shaped groove 14C, the rear thick upper plate 14A and the front thin upper plate 14B cover the entire plate thickness. Can be completely welded. Accordingly, since the root face is not provided, the thickness of the rear thick upper plate 14A and the front thin upper plate 14B can be reduced, and the welding strength of the joint portion between the rear thick upper plate 14A and the front thin upper plate 14B can be reduced. While securing, the weight of the upper plate 14 can be reduced.

  Similarly, when butt welding of the rear thick lower plate 15A and the front thin lower plate 15B is performed at the position of the V-shaped groove 15C, the rear thick lower plate 15A and the front thin lower plate 15B extend over the entire plate thickness. Can be completely welded. Accordingly, since the root face is not provided, the thickness of the rear thick lower plate 15A and the front thin lower plate 15B can be reduced, and the welding strength of the joint portion between the rear thick lower plate 15A and the front thin lower plate 15B can be reduced. The weight of the lower plate 15 can be reduced while ensuring.

  As a result, the joining strength between the rear thick side plate 12A and the front thin side plate 12B constituting the left side plate 12, the joining strength between the rear thick side plate 13A and the front thin side plate 13B constituting the right side plate 13, and the front thin side plate 12B and the bucket connection. The joint strength portion of the boss 20 with the port side 20B, the joint strength of the front thin side plate 13B and the starboard portion 20C of the bucket connecting boss 20, the rear thick upper plate 14A and the front thin upper plate 14B constituting the upper plate 14 The joining strength between the rear thick lower plate 15A and the front thin lower plate 15B constituting the lower plate 15 can be increased, the weight of the entire arm 11 can be reduced, and the strength and durability can be increased.

  Moreover, since it is not necessary to arrange a backing material on the back side of the V-shaped groove 12C formed between the rear thick side plate 12A and the front thin side plate 12B constituting the left side plate 12, the rear thick side plate 12A and the front plate The workability when butt welding the thin side plate 12B can be improved. Similarly, the butt welding between the rear thick side plate 12A and the front thin side plate 12B constituting the right side plate 13, the butt welding between the front thin side plate 12B of the left side plate 12 and the port side 20B of the bucket connecting boss 20, and the right side plate. 13 butt welding of the front thin side plate 13B and the starboard portion 20C of the bucket connecting boss 20, butt welding of the rear thick upper plate 14A constituting the upper plate 14 and the front thin upper plate 14B, and rear constituting the lower plate 15 The workability of the butt welding between the thick lower plate 15A and the front thin lower plate 15B can be improved.

  Further, in the present embodiment, the V-shaped groove 12C formed at the abutting portion 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 and the front thin side constituting the right side plate 13 are provided. V-shaped groove 13C formed at the abutting portion with the side plate 13B, V-shaped groove 14C formed at the abutting portion between the rear thick upper plate 14A and the front thin upper plate 14B constituting the upper plate 14, and the lower plate 15 The groove angle θ of the V-shaped groove 15C formed at the abutting portion between the rear thick lower plate 15A and the front thin lower plate 15B is set to a value of 43 degrees or more and 90 degrees or less.

  Thus, by supplying sufficient arc heat to the groove 12A6 of the rear thick side plate 12A and the groove 12B6 of the front thin side plate 12B, the rear thick side plate 12A and the front thin side plate 12B are joined together. It can be melted over the entire thickness, the inside of the groove 12C between the groove 12A6 and the front thin side plate 12B6 can be filled with molten metal without excess and deficiency, and between the rear thick side plate 12A and the front thin side plate 12B It is possible to form a weld bead 12F that is smoothly continuous.

  Similarly, a weld bead 13F that smoothly continues between the rear thick side plate 13A and the front thin side plate 13B constituting the right side plate 13 can be formed, and the rear thick upper plate 14A constituting the upper plate 14 and A smoothly continuous weld bead 14D can be formed between the front thin upper plate 14B and a smoothly continuous weld bead between the rear thick lower plate 15A and the front thin lower plate 15B constituting the lower plate 15. 15D can be formed.

  As a result, the joining strength between the rear thick side plate 12A constituting the left side plate 12 and the front thin lower plate 12B, the joining strength between the rear thick side plate 13A constituting the right side plate 13 and the front thin lower plate 13B, and the upper plate 14 are constituted. The joining strength between the rear thick upper plate 14A and the front thin upper plate 14B and the joining strength between the rear thick lower plate 15A and the front thin lower plate 15B constituting the lower plate 15 can be further increased, and the reliability of the arm 11 is improved. Can be increased.

  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 12C, 13C, 14C, 15C, 20D, 20E V-shaped groove 13 Right side plate 14 Upper plate 14A Rear thick upper plate 12A6, 13A6, 14A3, 14B3 , 15A3, 15B3, 20B1, 20C1 Groove 12B6, 13B6 Rear groove (groove)
12B7, 13B7 Front groove (groove)
14B Front thin upper plate 15 Lower plate 15A Rear thickness lower plate 15B Front thin lower plate 16 Thick rear plate 18 Boom connection boss 19 Internal partition 20 Bucket connection boss 20A Cylindrical boss portion 20B Port side 20C

Claims (5)

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,
Provided on the lower rear side of the left and right side plates is a boom connection 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,
In the construction machine arm 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,
The bucket connecting boss is provided with a flange portion that is located on both left and right sides of the cylindrical boss portion and extends toward the left and right side plates,
The front ends of the left and right side plates are each provided with a groove extending upward and downward by notching without a root face,
At the rear ends of the left and right flanges of the bucket connecting bosses, a groove extending upward and downward is provided by notching without a root face,
By matching the groove of the left and right side plates and the groove of the left and right buttock, a V-shaped groove having no root face and no gap is formed,
A construction machine arm characterized in that welding is performed by completely welding the left and right side plates and the left and right flanges at the position of the V-shaped groove. 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
The front end of the rear thick side plate and the rear end of the front thin side plate are each provided with a groove extending upward and downward by notching without a root face,
By matching the groove of the rear thick side plate and the groove of the front thin side plate, a V-shaped groove having no root face and no gap is formed,
The construction machine arm according to claim 1, wherein the rear thick side plate and the front thin side plate are melted at the position of the V-shaped groove to perform welding and complete welding . 2 of the previous SL upper plate has a thickness top plate after a plate is thick plate material located in the rear, before the thin top plate thickness is positioned on the front side of the rear thick upper plate consists of a thin plate material Formed by members,
The front end of the rear thick upper plate and the rear end of the front thin upper plate are each provided with a groove extending in the left and right directions by notching without a root face,
By matching the groove of the rear thick upper plate and the groove of the front thin upper plate, a V-shaped groove having no root face and no gap is formed,
Construction machinery arm according to claim 1 or 2 comprising a structure completely welded subjected to welding by Komu to dissolve and the front thin upper and the rear thick upper at the position of the V-groove. 2 of the front Symbol lower plate, a thickness lower plate after about the position and the plate thickness is thick plate on the rear side, and a thin lower plate before plate thickness is positioned on the front side of the rear thick lower plate consists of a thin plate material Formed by members,
The front end of the rear thick lower plate and the rear end of the front thin lower plate are each provided with a groove extending leftward and rightward by notching without a root face,
By matching the groove of the rear thin lower plate and the groove of the front thin lower plate, a V-shaped groove without a root face and without a gap is formed,
Construction machinery arm according to claim 1, 2 or 3 comprising a structure completely welded subjected to welding by Komu to dissolve and the front thin lower plate and the rear thick lower plate at a position of the V-groove .   The construction machine arm according to claim 1, 2, 3, or 4, wherein a groove angle of the V-shaped groove is set in a range of 43 degrees to 90 degrees.

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