JP2004268762A - Crawler frame of construction machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify structure by further reducing the number of components, where the leg of a center frame is formed of cast steel. <P>SOLUTION: A crawler frame 1 comprises the center frame 2 consisting of a center frame section 9 for supporting a turning bearing and legs 10, 11 provided at both right and left sides of the center frame section 9; and track frames 3A, 3B provided at tip sides of the legs 10, 11 of the center frame 2. In the crawler frame 1, the legs 10, 11 are formed by casting, and base ends of the legs 10, 11 are integrated with vertical walls. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a crawler frame of a construction machine such as a hydraulic excavator.
[0002]
[Prior art]
In general, a construction machine such as a hydraulic excavator includes a crawler traveling device (lower traveling body) having a crawler frame as an apparatus main body, and an upper revolving body that is rotatably mounted on the crawler traveling device. A work machine, cab, engine, etc. are mounted on the body.
[0003]
The crawler frame includes a center frame that pivotally supports the upper swing body at a central portion, and a track frame that is connected to both the left and right sides of the center frame and extends forward and backward. The idler and the driving wheel are respectively supported at the ends. The center frame includes a central frame portion that supports the slewing bearing and leg portions (leg portions) that are provided on both the left and right sides of the central frame portion and connect the central frame portion and the track frame. The structure is formed in a substantially H-shaped or substantially X-shaped frame shape in plan view. In this case, in order to receive the load applied to the slewing bearing in the center, a required number of vertical wall members are joined by welding between the upper surface plate on which the slewing bearing is placed and the lower surface plate disposed below the upper surface plate. A structure is employed (see Patent Documents 1, 2, and 3).
[0004]
[Patent Document 1]
JP-A-8-72615 [Patent Document 2]
JP 11-93209 A [Patent Document 3]
Japanese Patent Laid-Open No. 2000-230252
[Problems to be solved by the invention]
However, in the conventional center frame structure, the left and right track frames are connected to each other by a leg portion made of a sheet metal-worked steel plate, so that the shape of the steel plate is complicated and the number of parts is increased. Along with this, there is a problem that the number of welding points is increased, the number of welding processes is increased, and manufacturing takes much time and cost.
[0006]
Further, since the steel plate leg portion has a flat upper surface, mud that has entered the machine during work or traveling adheres to and accumulates on the upper surface of the leg portion. There is a problem that the bearing is damaged by intrusion, or moves to the upper surface of the track frame to prevent rotation of the upper roller, and further causes uneven wear of the upper roller.
[0007]
Therefore, in order to cope with such problems, the leg portion is formed by cast steel casting, and a flange portion is provided at the base end portion of the leg portion, and this flange portion is welded to the side surface of the box-shaped central frame portion. A center frame structure formed by joining is considered. According to such a structure, the number of parts can be reduced and the number of welding processes can be reduced, so that the machining process and the machining time can be greatly reduced. At that time, the cross-sectional shape of the leg portion is made into a cylindrical shape having a convex upper surface, so that the problem of mud adhesion and accumulation can be solved.
[0008]
However, even in the center frame structure including the cast leg portion, the center frame portion has a box-shaped sheet metal structure, and a structure in which the leg portion is welded to the sheet metal vertical wall is employed. There is still room for improvement in terms of the vertical wall structure as a strength member that receives the load applied to the slewing bearing and the number of parts, and further simplification of the structure is required.
[0009]
The present invention has been made in view of such circumstances. In the construction in which the leg portion of the center frame is formed of a casting, the construction machine can further reduce the number of parts and simplify the structure. It is an object to provide a crawler frame.
[0010]
[Means for solving the problems and actions / effects]
In order to achieve the above object, a crawler frame of a construction machine according to the present invention comprises:
In a crawler frame of a construction machine including a center frame that includes a center frame portion that supports a slewing bearing and leg portions that are provided on both right and left sides of the center frame portion, and a track frame that is provided on the front end side of the leg portion of the center frame.
The leg portion is formed by casting, and a vertical wall is integrally formed at the base end portion of the leg portion.
[0011]
According to the present invention, since the leg portion that connects the center frame portion and the track frame in the center frame is formed of a casting, the number of parts can be reduced as compared with that of sheet metal processing by a steel plate, and the welding location And the number of processing steps can be greatly reduced. Further, since the vertical wall is integrally formed at the base end portion of the leg portion, the vertical wall of the leg portion can receive a load applied to the swivel bearing, and the vertical frame in the central frame portion at the location where the leg portion is joined. Walls can be omitted. As a result, the number of parts can be further reduced, and the required strength can be ensured with a simple structure. In addition, by forming the leg portion from a casting, it is possible to easily change the thickness of the leg portion according to the load of the upper revolving body, and the upper surface shape of the leg portion can be easily made convex. Since it can form, it becomes the shape where mud falls easily, and the adhesion and accumulation can be prevented reliably.
[0012]
In the present invention, it is preferable that the leg portion is formed in a bifurcated shape and has a two-divided structure in the front and rear at the base portion. Moreover, it is preferable that the base part of the front-and-rear two-part structure of the leg part is an integrated structure by welding. By doing so, the leg portion can be casted more easily and the assembly thereof can be performed easily, and the center frame can be manufactured more easily.
[0013]
Moreover, it is preferable that the vertical wall of the said leg part is provided so that it may be located in the just under the circle stand which supports the said turning bearing. By doing so, the load of the upper swing body applied to the swing bearing can be directly received by the vertical wall of the leg portion, so that the most rational structure is provided for supporting the load of the upper swing body.
[0014]
In the present invention, it is preferable that a hole through which hydraulic piping is inserted is formed in the vertical wall of the leg portion, and an edge portion of the hole is formed thick. In this way, not only can the hydraulic piping be easily routed from the hydraulic pump provided on the upper swing body side to the hydraulic motor provided on the track frame side, but it can also contribute to weight reduction of the leg portion. . Moreover, by forming the edge of the hole thickly, the part can be strengthened, and it is possible to prevent the edge of the hole from being squared by the thick wall. Therefore, it is not necessary to attach a grommet to the piping hole.
[0015]
The welded portion between the upper and lower plates of the central frame portion and the leg portion is formed into a J-shaped groove so that the surface of the upper and lower plate and the surface of the leg portion are flush with each other. It is preferable. By doing so, the height of the leg portion can be increased and the rigidity can be increased, and the adjustment allowance can be taken with the J-shaped groove, so that it is easy to temporarily attach and align. In addition, there is an effect that stress concentration hardly occurs.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Next, specific embodiments of the crawler frame of the construction machine according to the present invention will be described with reference to the drawings.
[0017]
FIG. 1 is an overall perspective view of a crawler frame according to an embodiment of the present invention applied to a hydraulic excavator, FIG. 2 is a plan view of the crawler frame of this embodiment, and FIG. 3 is a front view thereof. FIG. 4 is a side view thereof. FIG. 5 shows a perspective view of the leg portion as viewed from below.
[0018]
The crawler frame 1 according to this embodiment includes a center frame 2 and track frames 3A and 3B that are arranged on both the left and right sides of the center frame 2 and extend in the vehicle body front-rear direction. Each of the track frames 3A and 3B includes a support frame 4 having a gate-shaped cross section disposed at the center, and an idler support 7 and a drive wheel support that are supported on the front and rear ends of the support frame 4 via plate members 5 and 6. 8, and the idler support 7 and the drive wheel support 8 are configured to support an idler and a drive wheel (both not shown), respectively.
[0019]
The center frame 2 includes a center frame portion 9 and leg portions 10 and 11 provided on the left and right sides of the center frame portion 9, and the tip portions of the leg portions 10 and 11 are respectively provided on the track frames 3A and 3B. It is comprised so that it may join to the side surface of the support frames 4 and 4. FIG.
[0020]
The central frame portion 9 is formed of a material such as a steel plate, and as shown in FIG. 6, a substantially semi-elliptical upper surface plate 12 having a hole 12a through which a swivel joint, piping and the like are inserted in the central portion, and a semi-elliptical shape A bottom plate 13 in which a front wall portion 13a is formed by vertically bending a front end portion of a shaped plate material, and a rear plate 14 formed by folding a required portion so as to cover the rear portions of the top plate 12 and the bottom plate 13. It is comprised by. The central frame portion 9 is assembled in a box shape with both side surfaces open, and then a circle base 15 for receiving and supporting a swivel bearing is placed and fixed on the upper surface of the upper surface plate 12.
[0021]
On the other hand, each leg part 10 and 11 distribute | arranged to the right and left of the said center frame part 9 is formed in the forked shape (planar view substantially V shape), and is made into a substantially X type by planar view as a whole, The load of the upper revolving body acting on the central frame portion 9 is distributed to the four leg portions so that the load is effectively supported. Since the left leg portion 10 and the right leg portion 11 are in a line-symmetrical relationship and have the same configuration, the left leg portion 10 will be described below as a representative.
[0022]
The left leg portion 10 has a bifurcated structure with a front leg portion 10A and a rear leg portion 10B at the front and rear at the base portion which is bifurcated. The leg portions 10A and 10B are integrally formed of a cast steel casting in a substantially pentagonal cross section with a convex upper surface, and the front leg portion 10A and the rear leg portion 10B are fitted to each other at the joint portion 10a on the base end side. It is integrated by welding joint.
[0023]
As shown in FIG. 5, a vertical wall 10b is integrally formed at the base end portion of the leg portion 10, and a circular hole (casting hole) communicating with the internal space of each leg portion 10A, 10B is formed in the vertical wall 10b. ) 10c and 10d are provided. Further, the base end surface of the leg portion 10, in other words, the surface of the vertical wall 10 b is formed in an arc surface having substantially the same curvature as the inner peripheral surface of the circle base 15, and when the leg portion 10 is joined to the central frame portion 9. Further, the vertical wall 10b is positioned immediately below the arc portion of the circle base 15.
[0024]
Further, a step portion 10e is formed at the base end portion of the leg portion 10 so that the base end portion side is stepped down. The step portion 10e has a curved shape that matches the shape of the side edges of the upper surface plate 12 and the lower surface plate 13 of the central frame portion 9 in a plan view. The upper surface plate 12, the lower surface plate 13 and the leg portion 10 are welded and joined to the portion 10e. The front surface portion 10f of the leg portion 10 on the proximal side from the step portion 10e is welded to the inner surface of the front wall portion 13a of the lower surface plate 13 in the central frame portion 9, and the rear surface portion 10g of the leg portion 10 is joined. Are welded to the inner side surface of the rear plate 14 in the central frame portion 9.
[0025]
On the other hand, a front flange portion 10A is provided with a joining flange portion 10h that is in contact with the inner wall surface of the support frame 4 of the track frame 3A and welded to the inner wall surface. Further, the front leg portion of the rear leg portion 10B is connected to the inner wall surface of the support frame 4 of the track frame 3A and welded to the inner wall surface, and is connected to the bonding flange portion 10i. In addition, a U-shaped joint portion 10j welded to the plate member 6 fixed to the rear end of the support frame 4 is provided.
[0026]
Next, the joining structure of the upper surface plate 12, the lower surface plate 13 and the leg portion 10 and the structure of the vertical plate 10b will be described in more detail with reference to FIG.
[0027]
As shown in the figure, a step portion 10e is formed at a joint portion between the upper surface plate 12 and the lower surface plate 13 and the leg portion 10, and a step portion 10e is formed between the upper surface of the step portion 10e and the end surface of the upper surface plate 12. A J-shaped groove 16 is formed between the lower surface and the end surface of the lower surface plate 13. Thus, by welding the J-shaped groove 16 portion, the surfaces of the upper surface plate 12 and the lower surface plate 13 and the surface of the leg portion 10 are flush with each other.
[0028]
By providing the J-shaped groove 16 in this way, the height of the leg portion 10 can be increased and its rigidity can be increased as compared with the conventional fillet welded one. In addition, since the adjustment allowance can be taken with this J-shaped groove 16, temporary attachment at the time of welding joining is facilitated, and alignment (absorption of dimensional tolerance between the leg portion 10 and the central frame portion 9) is easy. Become. In addition, there is an effect that stress concentration hardly occurs in the welded joint.
[0029]
Further, the holes (casting holes) 10c and 10d provided in the vertical wall 10b of the leg portion 10 are strengthened by forming the peripheral edge portion to be thick (with a frame), and the thick portion is rounded. Is formed. Then, one of the holes 10c (or 10d) is inserted with a hydraulic pipe 17 such as a hydraulic hose from a hydraulic pump on the upper swing body side to a hydraulic motor on the track frame 3A side. By adopting such a configuration, it is possible to easily handle the hydraulic piping and reduce the weight of the leg portion 10. In addition, since the thick part of the edge of the holes 10c and 10d is rounded, it does not damage the hydraulic piping 17 even if it hits the part, and adopts the conventional vertical wall made of sheet metal There is no need to attach a grommet to the peripheral edge of the hole as in the case of doing so. Further, such holes 10c and 10d do not need to be provided by laser processing or the like like a vertical wall made of sheet metal, and can be formed by die cutting, so that the manufacture is also easy.
[0030]
Moreover, according to this embodiment, since the vertical wall of the center frame part 9 in the part which joins the leg parts 10 and 11 can be abbreviate | omitted, a number of parts can be decreased. In addition, since the vertical wall 10b provided in the leg portions 10 and 11 is provided so as to be located immediately below the arc portion of the circle base 15, the vertical wall 10b directly applies the load of the upper swing body applied to the swing bearing. Therefore, there is an effect that it is advantageous in terms of strength.
[0031]
The leg portions 10 and 11 of the present embodiment have a substantially pentagonal cross section with a convex upper surface and are formed of a cast steel casting, so that mud invades the upper surfaces of the leg portions 10 and 11 during operation. Even so, the mud falls easily without adhering or accumulating on the upper surface. Therefore, it does not enter the slewing bearing part and damage the bearing, or it moves to the upper surface of the track frame and does not hinder the rotation of the upper wheel.
[0032]
In the present embodiment, the leg has been described as having a substantially pentagonal cross-sectional shape, but the cross-sectional shape may be a substantially triangular shape or a substantially quadrangular shape with an arcuate upper surface. Alternatively, it may be hexagonal.
[Brief description of the drawings]
FIG. 1 is an overall perspective view of a crawler frame according to an embodiment of the present invention.
FIG. 2 is a plan view of the crawler frame of the present embodiment.
FIG. 3 is a front view of the crawler frame of the present embodiment.
FIG. 4 is a side view of the crawler frame of the present embodiment.
FIG. 5 is a perspective view of a leg portion as viewed from below.
FIG. 6 is an exploded perspective view of a central frame portion.
FIG. 7 is a diagram showing a cross-sectional shape in the vicinity of a vertical wall of a leg portion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Crawler frame 2 Center frame 3A, 3B Track frame 9 Center frame part 10, 11 Leg part 10a Joint part 10b Vertical wall 10c, 10d Hole 10e Step part 12 Upper surface board 13 Lower surface board 14 Rear surface board 15 Circle stand 16 J-shaped groove 17 Hydraulic piping

Claims (6)

In a crawler frame of a construction machine including a center frame that includes a center frame portion that supports a slewing bearing and leg portions that are provided on both right and left sides of the center frame portion, and a track frame that is provided on the front end side of the leg portion of the center frame.
A crawler frame for a construction machine, wherein the leg portion is formed of a casting, and a vertical wall is integrally formed at a base end portion of the leg portion. 2. The crawler frame for a construction machine according to claim 1, wherein the leg portion is formed in a bifurcated shape and has a front and rear divided structure at a root portion thereof. The crawler frame for a construction machine according to claim 2, wherein a base part of the front and rear two-part structure of the leg part is formed into an integral structure by welding. The crawler frame for a construction machine according to any one of claims 1 to 3, wherein a vertical wall of the leg portion is provided so as to be positioned substantially directly below a circle base that supports the swivel bearing. The crawler frame for a construction machine according to any one of claims 1 to 4, wherein a hole through which hydraulic piping is inserted is formed in a vertical wall of the leg portion, and an edge portion of the hole is formed thick. The welded portion between the upper surface plate and lower surface plate of the central frame portion and the leg portion is made into a J-shaped groove so that the surface of the upper surface plate and lower surface plate and the surface of the leg portion are flush with each other. A crawler frame for a construction machine according to any one of claims 1 to 5.

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