JP4594544B2 - Swivel frame - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a swing frame of a hydraulic excavator.
[0002]
[Prior art]
As shown in FIG. 8, the swing frame of the excavator includes a center frame 51 having a pair of parallel main frames 50 and 50, and side frames 52 and 53 when attached to the left and right of the center frame 51. That is, the turning frame constitutes an upper turning body together with the cab and the fuel tank, and the upper turning body is supported by the lower traveling body via the turning mechanism so as to be turnable.
[0003]
By the way, as a revolving frame, what is lightweight is preferable. For this reason, it is conceivable to reduce the thickness of a portion that does not require much strength. Although the thickness of the turning mechanism portion corresponding portion of the turning frame, that is, the front end portion of the center frame 51 cannot be reduced, the thickness of the portion other than the turning mechanism portion corresponding portion can be reduced. Therefore, it has been proposed that the center frame 51 is composed of a front portion having a large wall thickness and a rear portion having a small wall thickness, and these are joined to form the center frame 51 (for example, the actual 3- 103355).
[0004]
[Problems to be solved by the invention]
However, the weight of the counterweight acts on the rear end portion of the center frame 51, and a large stress is generated at the joint portion between the front end portion and the rear end portion. Therefore, it is necessary to pay close attention to the joining work of this joining part, and the work has been complicated in order to ensure quality.
[0005]
The present invention has been made to solve the above-mentioned conventional drawbacks, and its purpose is to reduce the stress of the joint as described above, to facilitate the joining work, and to be stable over a long period of time. An object of the present invention is to provide a swivel frame that can maintain the reliability of a hydraulic excavator and can be reduced in weight.
[0006]
[Means and effects for solving the problems]
Accordingly, the turning frame of claim 1 is a turning frame of a hydraulic excavator having a lower traveling body and an upper swinging body supported by the lower traveling body via a pivotal support S so as to be capable of turning . a main frames 5, each of the main frames 5 includes a plate-like front portion 8 of the pivot portion S is formed in its lower position, the plate-like rear load is applied to the weight portion at the rear side 9 The plate-like front part 8 and the plate-like rear part 9 are connected via a joint part 17 extending in the vertical direction, and the pivotal part S acts via the plate-like front part 8. In the revolving frame configured to support the load of the upper revolving body supported by the front side fulcrum Y and the rear side fulcrum X below the plate-like front part 8 , the upper end 17 a of the joint 17 is connected to the rear of the pivot S. pivoting the lower end 17b which is arranged in the vicinity of the side supporting point X It is characterized in that provided on the rotation center O side of the (S).
[0007]
In the swivel frame of the first aspect, the upper end 17a of the joint portion 17 is provided closer to the swivel center O than the lower end 17b disposed in the vicinity of the rear fulcrum X of the pivot portion S. The stress on the upper end 17a side can be reduced. Therefore, the joining operation of the joining portion 17 can be facilitated, and as a result, the stable reliability as the turning frame can be maintained for a long time. As a result, the safety of the hydraulic excavator can be further improved.
[0008]
The swivel frame according to claim 2 is characterized in that the joint portion 17 has a linear shape that inclines toward the swivel center O from the lower end 17b toward the upper end 17a.
[0009]
In the revolving frame according to the second aspect, since the joint portion 17 is linear, it is easy to join and excellent in productivity, and a stable joined state can be ensured, and safety can be improved. .
[0010]
The turning frame of claim 3 is characterized in that the thickness dimension of the plate-like rear part 9 is set smaller than the thickness dimension of the plate-like front part 8.
[0011]
In the revolving frame of the third aspect, the weight of the entire revolving frame can be reduced by setting the thickness dimension of the plate-like rear part 9 to be smaller than the thickness dimension of the plate-like front part 8. Thereby, the workability and the like when assembling the hydraulic excavator can be improved, and the cost can be reduced. And since the stress in the junction part 17 reduces, even if weight reduction is achieved, a strength fall will not be caused.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall perspective view of a swivel frame. The swivel frame includes a center frame 1 and side frames 2 and 3 attached to the left and right of the center frame 1, and includes a driver's cab, fuel tank, and counterweight (not shown). Etc. constitute the upper revolving structure. Then, the upper swing body is supported by the lower traveling body through a pivotal support portion S (swing mechanism portion) (see FIG. 4) so as to be swingable.
[0013]
As shown in FIG. 2, the center frame 1 has main frames 5, 5 parallel to each other, and the main frames 5, 5 are connected by a connecting body 7. The main frames 5 and 5 each have a plate-like front portion 8 and a plate-like rear portion 9, and upper plates 10 and 10 are attached to a part of the plate-like front portion 8 or the plate-like rear portion 9. The plate-like front portion 8 is made of a substantially triangular metal plate in a side view, and the plate-like rear portion 9 is a substantially elongated rectangular metal plate in a side view in which the upper end (upper side) is sequentially inclined downward toward the rear. Consists of.
[0014]
That is, as shown in FIG. 3, the plate-like front portion 8 is formed of a horizontal bottom 8a, a front inclined side 8b, and a rear inclined side 8c, and the rear inclined side 8c is intermediate between the upper inclined portion 11 and the middle. It consists of an inclined portion 12 and a lower inclined portion 13. For this reason, the lower inclined portion 13 is an inclined side that inclines sequentially forward from the lower end upward. The plate-like rear portion 9 includes a bottom side 9a, an inclined side 9b that is inclined at substantially the same angle as the lower inclined portion 13, an upper side 9c that is sequentially inclined downward toward the rear, and a rear side 9d that extends in the vertical direction. Become. In this case, the inclination angle θ between the lower inclined portion 13 and the inclined side 9b is set to about 45 ° to 70 °, for example.
[0015]
Further, as shown in FIG. 5, the thickness dimension T2 of the plate-like rear part 9 is set smaller than the thickness dimension T1 of the plate-like front part 8. For example, the thickness dimension T1 is set to about 25 to 30 mm, and the thickness dimension T2 is set to about 20 to 24 mm. In this case, the plate-like front portion 8 and the plate-like rear portion 9 are joined by so-called groove welding. That is, the inclined side 9b of the plate-like rear portion 9 is formed from the first inclined portion 14, the second inclined portion 15, and the flat abutting portion 16 provided between the first and second inclined portions 14, 15. Thus, the butting portion 16 of the plate-like rear portion 9 is butted against the lower inclined portion 13 of the plate-like front portion 8 and is welded. Therefore, if the plate-like front portion 8 and the plate-like rear portion 9 are joined, a linear joining portion 17 extending in the vertical direction as shown in FIGS. 1 to 3 is formed. In the illustrated example, the plate-like front portion 8 and the plate-like rear portion 9 are arranged on the same outer surface, and no step is formed on the outer surface of the main frame 5 to be formed. Although it is arranged on the surface so that no step is generated on the inner surface of the main frame 5, the abutting portion 16 of the plate-like rear portion 9 is made to correspond to the center of the lower inclined portion 13 of the plate-like front portion 8. Thus, a step may be formed on the inner and outer surfaces. By the way, the inclination angles α and β of the first inclined portions 14 and 15 are set to about 35 °, for example, but of course not limited thereto.
[0016]
By the way, as shown in FIG. 4, the pivot frame S is disposed below the revolving frame configured as described above, that is, below the plate-like front portions 8 and 8 of the main frames 5 and 5. That is, the disc-shaped turning circle mounting plate 32 of the pivotal support S is attached to the lower surfaces of the plate-like front portions 8 and 8. For this reason, as shown in FIG. 3, the joint portion 17 extending vertically is arranged such that its upper end 17a is disposed closer to the turning center O than the lower end 17b, and turns sequentially from the lower end 17b toward the upper end 17a. It is a straight line inclined toward the center O side.
[0017]
In addition, counterweight frames 26 and 26 to which counterweights (weight portions) (not shown) are attached are projected from the rear ends of the main frames 5 and 5. Therefore, X and Y shown in FIG. 3 serve as fulcrums for loads such as a boom, an arm, and a bucket provided at the front of the upper swing body and a load such as a counterweight. In this case, the rear side fulcrum X is generated in the vicinity of the lower end 17 b of the joint portion 17, and the front side fulcrum Y is generated at the tip of the plate-like front portion 8.
[0018]
If the joint 17 is formed on a vertical line as shown by the phantom line in FIG. 3, a large stress is applied to the upper end 17a side of the vertical joint 17 as shown in FIG. Will occur. This stress distribution chart is obtained by setting a certain model, adding a load with X and Y as fulcrums, and examining the stress. Therefore, in the joint portion 17 as shown by the phantom line in FIG. 3, a large force acts on the upper end portion of the joint portion 17, and the joint portion 17 may be cracked or damaged. It is necessary to pay close attention to the joining operation of the joining portion 17. In FIG. 7, the darker the color, the greater the stress.
[0019]
However, if the upper end 17a of the joint portion 17 is provided closer to the turning center O than the lower end 17b disposed in the vicinity of the rear fulcrum X of the pivotal support S as in this embodiment, the upper end 17a side is By shifting to the fulcrum Y side with respect to the fulcrum X, the stress on the upper end 17a side of the joint portion 17 is reduced as shown in FIG. For this reason, the possibility that the above-described cracks, breakage, and the like occur in the joint portion 17 is reduced. Therefore, the joining operation of the joint portion 17 can be facilitated, and as a result, the hydraulic excavator using the swivel frame can maintain stable reliability over a long period of time. Note that the stress distribution diagram shown in FIG. 6 is a model in which a model in which the upper end 17a of the joint portion 17 is provided closer to the turning center O than the lower end 17b is applied and a load with X and Y as fulcrums is applied. Was investigated. In FIG. 6, the darker the color, the greater the stress.
[0020]
Further, in this embodiment, the main frame 5 is formed by dividing the plate-like front portion 8 into the plate-like rear portion 9, whereby the thickness dimensions T <b> 1 and T <b> 2 of the plate-like front portion 8 and the plate-like rear portion 9. And the thickness dimension T2 of the plate-like rear portion 9 can be set thin as described above. As a result, the weight of the entire turning frame can be set small, the weight can be reduced, the workability at the time of assembling the hydraulic excavator and the like can be improved, and the cost can be reduced. Furthermore, since the joint part 17 is linear, it is easy to join and excellent in productivity, and a stable joined state can be ensured, and safety can be improved.
[0021]
The specific embodiment of the swivel frame of the present invention has been described above. However, the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. is there. For example, the inclination angle θ of the joint portion 17 can be changed within a range in which the stress on the upper end 17a side of the joint portion 17 is reduced as shown in FIG. Moreover, a curved line shape, a staircase shape, etc. may be sufficient, without forming the junction part 17 in linear form. Further, when the plate-like front part 8 and the plate-like rear part 9 are joined, in the above embodiment, the K-shaped groove welding is adopted, but the I-type, V-type, X-type, L-type, J-type, double-sided Various groove welding such as J-shape, U-shape, and H-shape can be used.
[0022]
By the way, when assembling the swivel frame, the center frame 1 and the side frames 2 and 3 are formed separately and then connected to each other. Therefore, if the center frame 1 is assembled in the state shown in FIG. Side frames 2 and 3 whose side ends are so-called free ends are formed. For this reason, when the center frame 1 and the side frames 2 and 3 are assembled, there is a possibility that the side frame 2 is distorted. If the distortion is generated, it is necessary to correct the distortion. Work. Therefore, in the above embodiment, the main frame 5 is divided into the plate-like front portion 8 and the plate-like rear portion 9, so that the plate-like rear portion 9 and the like are assembled on the side frames 2 and 3 side to It is good also as a thing which does not generate | occur | produce distortion easily by making it into a closed structure without a free end.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a revolving frame of the present invention.
FIG. 2 is a perspective view of a center frame of the revolving frame.
FIG. 3 is a sectional view of a center frame of the revolving frame.
FIG. 4 is a plan view of a center frame of the revolving frame.
FIG. 5 is an enlarged cross-sectional view of a main part of a center frame of the revolving frame.
FIG. 6 is a stress distribution diagram of the swivel frame.
FIG. 7 is a stress distribution diagram for comparison.
FIG. 8 is an exploded perspective view of a conventional revolving frame.
[Explanation of symbols]
5 Main frame 8 Plate-like front part 9 Plate-like rear part 17 Joint part 17a Upper end 17b Lower end O Turning center S Pivot

Claims (3)

A swing frame of a hydraulic excavator having a lower traveling body and an upper swinging body supported by the lower traveling body via a pivot (S) so as to be pivotable, and a pair of parallel main frames (5) (5 ) comprises a respective main frame (5) (5), with the pivot portion to its lower position (the plate front (8 S) is formed), a plate acting load weight portion at the rear side The plate-like front portion (8) and the plate-like rear portion (9) are connected via a joint portion (17) extending in the vertical direction, and the pivot portion (S ), The load of the upper revolving body acting via the plate-like front part (8) is supported by the front fulcrum (Y) and the rear fulcrum (X) below the plate-like front part (8). in the configuration the rotating frame, the joint portion of the upper end (17a) of (17), the rear side fulcrum of the pivot portion (S) Revolving frame, characterized in that provided on the turning center (O) side of the pivot portion (S) than the lower end (17b) which is arranged in the vicinity of X). The swivel frame according to claim 1, wherein the joint portion (17) has a straight line shape that inclines toward the swivel center (O) from the lower end (17b) toward the upper end (17a). The turning frame according to claim 1 or 2, wherein a thickness dimension of the plate-like rear part (9) is set smaller than a thickness dimension of the plate-like front part (8).

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