JP2008240343A - Arm of working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an arm of a working machine, which can maintain high strength on the side of its leading end, which reduces the number of man-hours for the manufacture of the arm, and which can achieve weight reduction. <P>SOLUTION: A pair of right and left side walls, and a connecting wall for connecting one-vertical-side portions of the pair of side walls together are provided in a U-shape; an arm-leading-end member with first and second connecting bosses is integrally formed between the pair of side walls by casting; an arm body, in which the pair of right and left side walls, and the connecting wall for connecting the one-vertical-side portions of the pair of side walls together are provided in the U-shape, is composed of a sheet metal; a base side of the arm-leading-end member and a leading-end side of the arm body are joined and fixed together by welding; and a blocking plate, which faces the connecting wall of the arm body and that of the arm-leading-end member, is fixed throughout the arm-leading-end member and the arm body so as to block an opening between the arm-leading-end member and the arm body. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an arm of a working machine provided on a working machine such as a construction machine such as a backhoe.

The excavation work machine such as a backhoe includes an arm supported swingably on the tip side of the boom, and a cylindrical first connection boss for connecting a bucket (work tool) to the tip side of the arm; Some of them are provided with a cylindrical second connection boss for connecting a link of a bucket cylinder (work implement cylinder) (for example, Patent Documents 1 to 3).
As shown in FIGS. 22 and 23, the arm of this type of conventional working machine has a connecting wall that connects the pair of left and right side walls 101 and the upper end side of the pair of side walls 101 from the distal end to the proximal end side. An arm body 103 having a U-shaped cross section having a (back wall) 102, and a closing plate (abdominal plate) 104 fixed by welding between the pair of side walls 101 so as to close the lower end opening of the arm body 103. In general, the first connecting boss 106 is fixed to the distal end portion of the arm body 103 by welding, and the second connecting boss 107 is inserted through the rear of the first connecting boss 106 and fixed by welding. (For example, Patent Documents 1 to 3).
JP 2003-34947 A JP 2003-34946 A JP 2001-82406 A

  Conventionally, when the first connecting boss 106 and the second connecting boss 107 are welded to the side wall 101 of the arm body 103, there is a gap between the first connecting boss 106 and the second connecting boss 107 and the side wall 101 of the arm body 103. In order to fill this gap and reduce the stress that tends to increase the stress value during excavation and other work, as shown in FIG. 22, inner welding W1 and two-layer welding W2 are performed. The reinforcing plate 108 is provided between the first connecting boss 106 and the second connecting boss 107, and the first connecting boss 106 and the second connecting boss 107 are connected by the reinforcing plate 108. The mounting work of the first connecting boss 106 and the second connecting boss 107 to the arm requires a lot of man-hours, and there is a problem that the number of constituent members increases and the weight of the tip end side of the arm main body 103 becomes heavy.

  In view of the above-described problems, the present invention can maintain the strength of the tip end side of the arm high, reduce the number of manufacturing steps of the arm, and reduce the weight.

The technical means of the present invention for solving this technical problem is an arm of a work machine in which a first connection boss and a second connection boss are provided on the tip side.
An arm tip member having a pair of left and right side walls and a connecting wall that connects one side in the vertical direction of the pair of side walls in a U-shape and having the first connecting boss and the second connecting boss between the pair of side walls. An arm main body formed of a casting and having a U-shaped connecting body that connects a pair of left and right side walls and one side of the pair of side walls in the vertical direction is formed of a sheet metal, and the base side of the arm tip member and the arm main body The arm tip member and the arm body are joined and fixed to each other by welding, and the closing plate facing the connecting wall of the arm body and the connecting wall of the arm tip member closes the opening between the arm tip member and the arm body. It is in the point fixed over.

In addition, another technical means of the present invention is that the joint portion between the base side of the arm tip member and the tip side of the arm body has a long arm joint length between the arm tip member and the arm body. Is at a point that is inclined with respect to.
According to another technical means of the present invention, the joint end surface on the base side of the arm tip member is inclined so as to go to the arm tip as it goes outward in the left-right direction or the up-down direction, When the side and the front end side of the arm main body are abutted, a groove for welding is formed between the base side of the arm front end member and the front end side of the arm main body.

Another technical means of the present invention is that the inner surface of the distal end side of the arm body is located on the base side of the arm distal end member and on the inner side in the left-right direction or the vertical direction with respect to the joint end surface on the base side of the arm distal end member. The fitting projection piece is integrally provided so as to extend along the line, and the fitting projection piece includes a pair of side wall projections corresponding to the pair of side walls and a connection wall projection corresponding to the connection wall. And is fitted into the base side of the arm body.
According to another technical means of the present invention, the arm tip member is integrally formed of cast steel that is a casting, and a joint portion between the base side of the arm tip member and the tip side of the arm body acts on the arm tip member. It is in the point inclined forward and downward toward the arm tip so that the load to be received is received by the arm body.

  According to the present invention, the arm tip member having the first connecting boss and the second connecting boss is integrally formed of a casting, and the base side of the arm tip member and the tip side of the arm main body are joined and fixed by welding, and are closed. Since the plate is welded across the arm tip member and the arm body so as to close the opening between the arm tip member and the arm body, the first connection boss and the second connection boss are connected to the arm body as in the prior art. It is no longer necessary to weld directly to the side wall of the steel plate, inner welding or two-layer welding as in the prior art, or by providing a reinforcing plate between the first connecting boss and the second connecting boss, There is no need to connect the connecting boss and the second connecting boss, and the work of attaching the first boss and the second boss to the arm body can be omitted. In addition, since the arm tip member is formed of a casting, the arm tip can be formed into a complicated shape with high accuracy. Therefore, the shape of the joint portion of the arm tip member to the arm main body on the base end side is changed to the arm. A complicated shape suitable for welding to the distal end side of the main body can be obtained, and therefore, the arm tip member can be easily and reliably joined and fixed to the arm main body by welding. In addition, since the first connection boss and the second connection boss are formed integrally with the arm tip member, stress is concentrated on the connection portion between the first connection boss and the second connection boss and the arm tip member, and the strength is weak. This can also be prevented, and the strength can be kept high.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes a backhoe exemplified as an (excavation) working machine. The backhoe 1 mainly includes an upper swing body 2 and a lower traveling device 3, and a swivel base 6 is arranged in a vertical direction. A small size in which the rear surface side of the swivel base 6 is formed in an arc shape (substantially arcuate) in plan view so that the rear surface side of the swivel base 6 does not protrude beyond the lateral width of the traveling device 3 even when turning around the pivot axis This is called a rear small turning backhoe.
Note that the traveling direction of the backhoe 1 (the left-right direction in FIG. 1) is referred to as the front-rear direction, and the lateral direction orthogonal to the front-rear direction (the paper penetration direction in FIG.

Moreover, the machine body of the work machine 1 is comprised by the turntable 6, the traveling apparatus 3, etc. FIG.
The traveling device 3 rotatably supports an idler 8, a drive wheel 9, a track roller 10 and a carrier roller 11 on both left and right sides of the track frame 7, and has an endless belt-like elasticity in the form of a rubber crawler (or iron crawler). A crawler type traveling device is employed in which the crawler 4 is wound and the driving wheel 9 is driven by a hydraulic motor or the like.
The swivel body 2 includes a swivel base 6 that is supported on the travel device 3 so as to be swivel around a swivel axis in the vertical direction, a working device (excavation device) 12 provided at the front of the swivel base 6, and the swivel base 6. A driver's seat 13 provided above and various devices mounted on the swivel 6 such as an engine, a fuel tank, a hydraulic pump, a hydraulic oil tank, a radiator, and a battery are configured.

The swivel base 6 is provided with a counterweight 15 (protector) at the rear part that balances the weight of the working device 12 and the like provided at the front part of the swivel base 6 and constitutes the rear part of the swivel base 6.
A pair of upper and lower support brackets 16 is provided at the front portion of the swivel base 6 so as to protrude forward, and a support bracket 17 is supported by the support bracket 16 so as to be swingable left and right around the vertical axis.
A boom 18 supported by the support bracket 17 so as to be swingable around a support shaft in the left-right direction; an arm 19 supported swingably around a support shaft 24 in the left-right direction; The working device 12 is mainly composed of a bucket 20 attached to the tip end side of the arm 19 so that a squeeze / dump operation is possible. The boom 18, the arm 19 and the bucket 20 are each a boom cylinder 21 made of a hydraulic cylinder. The arm cylinder 22 and the bucket cylinder 23 are operable.

A front end of the traveling device 3 is provided with a dozer device 5 (tilt angle dozer device).
Between the support bracket 30 provided on the base end side of the arm 19 and the support bracket 31 provided in the middle in the longitudinal direction of the boom 18, the arm cylinder 22 made of a hydraulic cylinder is interposed, and this arm cylinder The arm 19 is swung back and forth by the withdrawal and withdrawal of the 22 piston rod.
The bucket 20 is pivotally supported by a first connecting boss 35 provided at the tip of the arm 19 via a mounting bracket 33 so as to be rotatable around a support shaft 36 in the left-right direction. In addition, one end of the first link 37 is pivotally supported on the bucket 20 via a mounting bracket 33 so as to be rotatable around a support shaft 38 in the left-right direction, and the proximal end of the first connecting boss 35 on the distal end side of the arm 19 is supported. One end side of the second link 40 is pivotally supported around the support shaft 41 in the left-right direction by the second connecting boss 39 provided near the other end side of the first link 37 and the second link 40. The comrades are pivotally attached to each other so as to be rotatable around a support shaft 42 in the left-right direction, and the bucket cylinder 23 formed of a hydraulic cylinder is interposed between the pivotally attached portion and the support bracket 30. The bucket 20 swings back and forth (squeeze / dump operation) by the withdrawal and withdrawal of the piston rod of the bucket cylinder 23.

As shown in FIGS. 2 to 7, the arm 19 includes an arm main body 44, an arm tip member 45 configured separately from the arm main body 44, and a closing plate (abdominal plate) 46. The base side of the arm tip member 45 and the tip side of the arm main body 44 are joined and fixed by welding.
The arm body 44 is configured by sheet metal (processing), and has a pair of left and right side walls 49 and a connecting wall (back wall) 50 that connects one side (upper end) side of the pair of side walls 49 in a vertical direction, The lower end side of the arm body 44 is opened.
The arm tip member 45 is integrally formed of cast steel, which is a type of casting, and has a pair of left and right side walls 53 and a connecting wall (back wall) 54 that connects one side (upper end) of the side wall 53 in the vertical direction. The first connecting boss 35 and the second connecting boss 39 are integrally provided between the pair of side walls 53, and the lower end side of the arm tip member 45 is opened.

  The first connection boss 35 and the second connection boss 39 are formed in a cylindrical shape, and both left and right end portions protrude outward from the pair of side walls 53. The first connection boss 35 is provided at the distal end of the arm distal end member 45, and the second connection boss 39 is provided at a midway portion in the front-rear direction closer to the proximal end than the first connection boss 35. Both end portions are integrally connected to the tip ends of the pair of side walls 53, and the upper portion of the first connecting boss 35 is integrally connected to the tip end portion of the connecting wall 54. Both end portions in the left-right direction of the second connecting boss 39 are integrally connected to the center portion of the pair of side walls 53, and the upper portion of the second connecting boss 39 is integrated with the center portion in the front-rear direction of the connecting wall 54 via the connecting portion 55. It is formed by connecting.

The closing plate 46 is disposed so as to face the connecting wall 50 of the arm main body 44 and the connecting wall 54 of the arm front end member 45, and the arm front end member 45 so as to close the lower end opening of the arm front end member 45 and the arm main body 44. Are fixed (welded) to the arm tip member 45 and the lower end of the arm body 44.
The joint between the base side of the arm tip member 45 and the tip side of the arm main body 44 is inclined forward and downward toward the tip of the arm 19 and is inclined with respect to the arm width direction, whereby the arm tip member 45 and the arm The joint length with the main body 44 is increased, and the arm main body 44 can receive a load acting on the arm tip member 45.

The joint end surface 45a on the base side of the arm tip member 45 is inclined so as to go to the tip of the arm 19 as it goes outward in the left-right direction or the up-down direction, and the base side of the arm tip member 45 and the tip side of the arm body 44 , A groove A for welding is formed between the base side of the arm tip member 45 and the tip side of the arm main body 44.
A fitting projecting along the inner surface of the distal end side of the arm body 44 on the proximal side of the arm distal end member 45 and on the inner side in the horizontal direction or the vertical direction with respect to the joining end surface 45a on the proximal side of the arm distal end member 45 The protrusions 57 are provided integrally, and the fitting protrusions 57 have a pair of side wall protrusions 59 corresponding to the pair of side walls 53 and a connection wall protrusion 60 corresponding to the connection wall 54 in a U-shape. The arm body 44 is fitted on the base side.

A support boss 62 is provided at the lower end on the proximal end side of the arm body 44. The support boss 62 is formed in a cylindrical shape, and is fixed to the lower ends on the base end side of the pair of side walls 49 of the arm body 44 by welding. As described above, the arm 19 is supported on the distal end side of the boom 18 through the support boss 62 so as to be swingable around the support shaft 24 in the left-right direction.
A reinforcing plate 63 is provided at the lower part of the base end side of the arm body 44. The reinforcing plate 63 is bent in a U-shape, and is fixed between the pair of side walls 49 of the arm body 44 by welding or the like, and the front end of the reinforcing plate 63 is fixed to the support boss 62 by welding or the like. In addition, a pair of left and right reinforcing side plates 64 is provided at the lower portion of the base end side of the arm body 44. The reinforcing side plates 64 are arranged so as to overlap with the outer surfaces of the pair of side walls 49 and are fixed to the pair of side walls 49 by welding or the like.

An upper connecting plate 66 is provided on the upper part of the base end side of the arm main body 44. The upper connecting plate 66 is disposed so as to close the upper opening between the connecting wall 50 on the rear side of the arm body 44 and the pair of side walls 49, and the connecting wall 50, the pair of side plates 49, and the support boss of the arm body 44. It is fixed to 62 etc. by welding or the like. The mounting bracket 30 protrudes from the base side of the arm body 44 through the upper connecting plate 66. The mounting bracket 30 has a pair of left and right side plates 68, and the pair of side plates 68 are connected to each other by a plurality of connecting members 69.
A work tool cylinder pivot part 71 is provided at the front end of the mounting bracket 30, and an arm cylinder pivot part 72 is provided at the rear end. The arm cylinder 22 is connected between the arm cylinder pivot 71 and the mounting bracket 31 provided in the middle in the longitudinal direction of the boom 12, and the arm 19 can swing back and forth or up and down by the expansion and contraction of the arm cylinder 22. Yes.

A rear end portion of the bucket cylinder 23 is pivotally supported by a work tool cylinder pivot portion 71 of the mounting bracket 30 so as to be swingable about a left and right pivot.
According to the above embodiment, the arm tip member 45 having the first connection boss 35 and the second connection boss 39 is integrally formed by casting, and the base side of the arm tip member 45 and the tip side of the arm main body 44 are formed. Since the joining plate is fixed by welding, and the closing plate 46 is fixed across the arm tip member 45 and the arm main body 44 so as to close the opening between the arm tip member 45 and the arm main body 44, There is no need to weld the first connecting boss and the second connecting boss directly to the side wall of the arm body, and inner welding or two-layer welding is performed as in the prior art, or between the first connecting boss and the second connecting boss. There is no need to provide a reinforcing plate to connect the first connecting boss and the second connecting boss with the reinforcing plate, and the work of attaching the first connecting boss and the second connecting boss to the arm body is omitted. be able to. In addition, since the arm distal end member 45 is formed of a casting, the arm distal end portion can be formed in a complicated shape with high accuracy. Therefore, the shape of the joint portion of the arm distal end member 45 to the arm main body 44 on the proximal end side Can be formed into a complicated shape suitable for welding to the distal end side of the arm main body 44. Therefore, the arm tip member 45 can be easily and securely joined and fixed to the arm main body 44 by welding. In addition, since the first connecting boss 35 and the second connecting boss 39 are formed integrally with the arm tip member 45, stress is applied to the connecting portion between the first connecting boss 35 and the second connecting boss 39 and the arm tip member 45. Concentration and weakening of the strength can be prevented, and the strength of the arm 19 on the tip side can be kept high.

  Further, since the joint portion between the base side of the arm tip member 45 and the tip side of the arm body 44 is inclined with respect to the arm width direction, the joint length between the arm tip member 45 and the arm body 44 becomes long. The arm tip member 45 can be bonded and fixed to the arm body 44 more securely and firmly. Further, since the joint end surface 45a on the base side of the arm tip member 45 is inclined so as to go to the arm tip as it goes outward in the left-right direction or the up-down direction, the base side of the arm tip member 45 and the arm main body 44 By abutting the distal end side, a groove A for welding is reliably formed between the base side of the arm distal end member 45 and the distal end side of the arm main body 44, and using this groove A, The arm tip member 45 can be easily and reliably welded to the arm body 44.

  Also, a fitting projecting along the distal inner surface of the arm body 44 on the proximal side of the arm distal end member 45 and on the inner side in the horizontal direction or the vertical direction from the joint end surface 45a on the proximal side of the arm distal end member 45. A mating protrusion 57 is integrally provided, and the fitting protrusion 57 includes a pair of side wall protrusions 59 corresponding to the pair of side walls 53 and a connection wall protrusion 60 corresponding to the connection wall 54 in a U-shape. And is fitted on the base side of the arm main body 44, so that when the base side of the arm tip member 45 is welded to the front end side of the arm main body 44, the fitting protrusion 57 is placed on the front end side of the arm main body 44. By fitting inside, the arm tip member 45 can be positioned and fixed with respect to the arm main body 44, so that the arm tip member 45 can be accurately positioned with respect to the arm main body 44 and welded easily and reliably. To do Kill. Also, the fitting protrusion 57 can be welded to the distal end side of the arm main body 44, whereby the arm distal end member 45 can be more firmly fixed to the arm main body 44.

Further, the joint between the base side of the arm tip member 45 and the tip side of the arm body 44 is inclined forward and downward toward the arm tip so that the arm body 44 receives a load acting on the arm tip member 45. Therefore, the load applied to the arm tip member 45 can be effectively received by the arm main body 44 during excavation work or the like. From this point, the arm tip member 45 is more firmly fixed to the arm main body 44. Can be.
14 to 21 show other embodiments. As shown in FIG. 14, a thumb-like (arm-like) member called a thumb 75 is attached to the distal end side of the arm 19. The thumb 75 is for clamping an object to be clamped with the bucket 20, and the base end side of the thumb 75 is rotatable around the support shaft 36 in the left-right direction to the first connecting boss 35 at the tip end side of the arm 19. It is pivotally supported by and swingably supported.

A thumb bracket 77 is fixed to the arm 19 on the side of the closing plate (abdominal plate) 46, and one end of a thumb cylinder 78 is supported by the thumb bracket 77.
The thumb bracket 77 has a pair of left and right mounting walls 81 and a support wall 82 that connects end portions on the bottom side of the pair of mounting walls 81, and the support wall 82 of the thumb bracket 77 overlaps with the closing plate 46 of the arm 19. And fixed by welding.
A base portion of a cylinder body 78a of the thumb cylinder 78 is disposed between the pair of mounting walls 81 of the thumb bracket 77, and a base portion (one end portion of the thumb cylinder 78) of the cylinder body 78a is disposed between the pair of mounting walls 81 in the left-right direction. It is pivotally supported around a pivot 83 so as to be rotatable. The tip end side of the piston rod 78b of the pair of thumb cylinders 78 is pivotally attached to the middle part of the thumb 75 in the longitudinal direction so as to be rotatable around a support shaft in the left-right direction. Therefore, the thumb 75 is configured to swing around the support shaft 36 by extending and retracting the thumb cylinder 78 (withdrawing and retracting the piston rod 78b of the thumb cylinder 78).

As shown in FIGS. 15 to 20, the thumb bracket 77 is integrally formed of cast steel which is a kind of casting, and a pair of mounting walls 81 and a support wall 82 are integrally formed. A pair of mounting walls 81 are provided with mounting holes 85 through which the support shaft 83 is inserted facing left and right, and a holding cylinder 86 for inserting and holding a retaining pin that is inserted through the support shaft 83 into one mounting wall 81. Are integrally provided, and the holding cylinder 86 is provided with an insertion hole 87 for insertion of a retaining pin.
A recess 88 is provided on the attachment surface 82 a of the support wall 82 to the closing plate 46. As shown in FIG. 17, the recesses 88 are paired on the left and right on the mounting surface 82 a of the support wall 82, and are recessed so as to leave the outer peripheral portion a <b> 1 of the mounting surface 82 a and the central portion a <b> 2 in the left-right direction.

  The other points are the same as those in the above embodiment, and the arm tip member 45 having the first connecting boss 35 and the second connecting boss 39 is made of cast steel as shown by the chain line in FIG. The arm tip is formed integrally, and the base side of the arm tip member 45 and the tip side of the arm body 44 are joined and fixed by welding, and the closing plate 46 closes the opening of the arm tip member 45 and the arm body 44. The member 45 and the arm main body 44 are fixed to each other, and the arm tip member 45 can be easily and reliably joined and fixed to the arm main body 44 by welding as in the case of the above-described embodiment.

As shown in FIG. 21, the thumb 75 includes a pair of left and right side wall bodies 91, and the pair of left and right side wall bodies 91 are connected to each other by a cylindrical connecting member 92 and a connecting rod 93. A cylindrical mounting boss 94 is provided at the front end, and is supported by the tip of the arm 19 via the mounting boss 94 so as to be swingable around the support shaft 36. As described above, the front end side of the piston rod 78b is pivotally attached to the middle portion of the thumb 75 between the connecting member 92 and the connecting rod 93 so as to be rotatable about a left and right support shaft.
According to the embodiment, by expanding and contracting the bucket cylinder 23, the bucket 20 can be swung around the support shaft 36 in the left-right direction to perform a scooping operation and a dumping operation. Further, by extending and retracting the thumb cylinder 78, the thumb 75 can swing around the support shaft 36, and the object to be clamped can be held between the bucket 20 and the thumb 75.

The thumb bracket 77 is integrally formed of cast steel, which is a casting, and a pair of mounting walls 81 and a support wall 82 are integrally formed. A recess 88 is provided on the mounting surface 82a of the support wall 82 to the closing plate 46. Therefore, the area where the support wall 82 is overlapped and fixed to the closing plate 42 is reduced to reduce the processing surface of the thumb bracket 77, and the thumb bracket 77 is lightened and the thumb bracket is used during excavation work. 77 and the stress concentration on the welded portion of the arm 19 can be reduced.
In the above-described embodiment, a backhoe that is a dedicated machine for excavation work machines is exemplified as the work machine. However, the work machine to which the present invention is applied is attached to the rear portion of the tractor 2 in a work vehicle called TLB. The present invention is employed in a working machine having an arm 19.

  In the embodiment, the arm body 44 has a pair of left and right side walls 49 and a connecting wall (back wall) 50 that connects the upper end sides of the pair of side walls 49 in a U-shape. The lower end side is opened, and the arm tip member 45 has a pair of left and right side walls 53 and a connecting wall (back wall) 54 that connects the upper end sides of the side walls 53 in a U-shape. The closing plate 46 is fixed to the arm tip member 45 and the lower ends of the arm body 44 across the arm tip member 45 and the arm body 44 so as to close the lower end openings of the arm tip member 45 and the arm body 44. However, instead of this, the arm body 44 is formed in a U-shape having a pair of left and right side walls 49 and a connecting wall (bottom wall) 50 that connects the lower ends of the pair of side walls 49. The upper end side of the arm body 44 is opened The arm tip member 45 is formed in a U shape having a pair of left and right side walls 53 and a connecting wall (bottom wall) 54 connecting the lower end sides of the side walls 53, and the upper end side of the arm tip member 45 is opened. The closing plate 46 is fixed to the upper ends of the arm tip member 45 and the arm body 44 across the arm tip member 45 and the arm body 44 so as to close the upper end openings of the arm tip member 45 and the arm body 44. (Welding) may be performed.

Further, in the above-described embodiment, the joint portion between the base side of the arm tip member 45 and the tip side of the arm body 44 is inclined forward and downward toward the tip of the arm 19 and is inclined with respect to the arm width direction. However, instead of this, the joint portion between the base side of the arm tip member 45 and the tip side of the arm main body 44 is tilted forward and tilted toward the tip of the arm 19 to be tilted with respect to the arm width direction. The joint length between the arm tip member 45 and the arm main body 44 may be increased.
In the above-described embodiment, the arm tip member 45 is integrally formed of cast steel, which is a type of casting, but instead, the arm tip member 45 is integrally formed of cast iron other than cast steel or other castings. May be.

  INDUSTRIAL APPLICABILITY The present invention can be used for excavation work machines such as a work vehicle called TLB and a backhoe that are provided with a backhoe attached to the rear part of a tractor.

It is a side view of the working machine which shows one embodiment of this invention. It is a top view of the arm. It is a side view of the arm. It is a bottom view of the arm. It is a top view of the arm front-end | tip part. It is a side view of the arm front-end | tip part. It is a partially cutaway bottom sectional view of the arm tip. It is a top view of the arm tip member. It is a left view of the arm tip member. It is a partially cutaway bottom sectional view of the arm tip member. It is a left side sectional view of the arm tip member. It is a rear view of the arm tip member. It is the sectional view on the AA line of FIG. It is a side view of the bucket, the thumb, and the arm tip portion showing another embodiment. It is a top view of the same thumb bracket. It is a right view of the same thumb bracket. It is a bottom view of the same thumb bracket. It is a left view of the same thumb bracket. It is a rear view of the same thumb bracket. It is a back sectional view of the thumb bracket. It is a top view of the same thumb. It is a top view of the arm front-end | tip part which shows a prior art example. It is a side view of the arm front-end | tip part.

Explanation of symbols

1 Backhoe (work machine)
DESCRIPTION OF SYMBOLS 19 Arm 35 1st connection boss 39 2nd connection boss 44 Arm main body 45 Arm tip member 45a Joining end surface 49 Side wall 50 Connection wall 53 Side wall 54 Connection wall 57 Fitting protrusion 59 Side wall protrusion part 60 Connection wall protrusion part

Claims (5)

In the arm of the working machine provided with the first connection boss (35) and the second connection boss (39) on the distal end side,
A pair of left and right side walls (53) and a connecting wall (54) for connecting one side in the vertical direction of the pair of side walls (53) are U-shaped, and the first connecting boss is interposed between the pair of side walls (53). An arm tip member (45) having (35) and a second connecting boss (39) is integrally formed of a casting, and connects the pair of left and right side walls (49) and the pair of side walls (49) in one vertical direction. The arm main body (44) having a U-shaped connection wall (50) is made of sheet metal, and the base side of the arm front end member (45) and the front end side of the arm main body (44) are joined and fixed by welding, The closing plate (46) facing the connecting wall (50) of the arm body (44) and the connecting wall (54) of the arm tip member (45) is an opening between the arm tip member (45) and the arm body (44). Arm tip member (45) and arm book Arm of the working machine, characterized in that it is secured over the (44).   The arm width direction is such that the joint length between the base side of the arm tip member (45) and the tip side of the arm main body (44) is increased in the joint length between the arm tip member (45) and the arm main body (44). The working machine arm according to claim 1, wherein the working machine arm is inclined with respect to the working machine.   The joint end surface (45a) on the base side of the arm tip member (45) is inclined so as to go to the arm tip as it goes outward in the left-right direction or the up-down direction, and the base side of the arm tip member (45) and the arm A groove (A) for welding is formed between the base side of the arm tip member (45) and the tip side of the arm main body (44) when the front end side of the main body (44) is abutted. It is comprised, The arm of the working machine of Claim 1 or 2 characterized by the above-mentioned.   An inner surface on the distal end side of the arm main body (44) on the base side of the arm distal end member (45) and on the inner side in the horizontal direction or the vertical direction with respect to the joining end surface (45a) on the base side of the arm distal end member (45). A fitting protrusion (57) protruding so as to extend along the line is integrally provided, and the fitting protrusion (57) has a pair of side wall protrusions (59) corresponding to the pair of side walls (53) and a connecting wall ( 54) The connecting wall protrusion (60) corresponding to (54) has a U-shape and is fitted into the base side of the arm body (44). Arm of work machine as described in the section.   The arm tip member (45) is integrally formed of cast steel, which is a casting, and the joint between the base side of the arm tip member (45) and the tip side of the arm body (44) acts on the arm tip member (45). The arm of the working machine according to any one of claims 1 to 4, wherein the arm is tilted forward and downward toward the tip of the arm so as to receive a load to be received by the arm body (44).

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