JPH0587049U - Car body of undercarriage of construction machinery - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] The main frame that constitutes the car body in construction machines such as hydraulic excavators and the slewing bearing mounting cylinder provided on the main frame are integrated as much as possible to simplify manufacturing, and Improve strength. A main frame 11 is formed by welding a lower flange 12 formed of a single plate and an integrally molded upper member 13 so as to overlap the lower flange 12, and a track is provided on both left and right sides of the main frame 11. Two coupling holes for bolting to the frame communicate with the upper member 13 and the lower flange 13 and are open. The cylinder 10 at the center of the upper surface of the upper member 13 is welded or integrally formed with the upper member 13.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a car body of a lower traveling body of a construction machine such as a hydraulic excavator on which an upper swing body is mounted.

[0002]

[Prior Art]

 FIG. 3 shows an overall side view of the crawler type hydraulic excavator 1. An upper revolving structure 2 is attached to a lower traveling structure 3 including left and right crawler belt type traveling devices 5 via a revolving bearing 4 shown in FIG. In the slewing bearing 4 shown in FIG. 4, the outer race 4a is usually positioned by the knock pin 14 with respect to the structural portion of the upper slewing body 2 and then mounted by a plurality of bolts 16, and the base frame 6 (in the frame portion of the lower traveling body 3) The inner race gear 4b is attached to the cylindrical portion of the carbody 8 in FIG. 5) with bolts 15 and the like, and the upper revolving superstructure 2 is rotated by the revolving pinion 31 of the hydraulic motor 30 attached thereto meshing with the inner race gear 4b. Then, it turns with respect to the lower traveling structure 3.

FIG. 5 is a perspective view of the base frame, and FIG. 6 is a plan view of the same. As shown in FIG. 6, the left and right track frames 7 and the central car body 8 that support the left and right lower traveling devices 5 of the base frame 6 are provided with bolts 9 or the like for narrowing the vehicle width during transportation or split transportation. It is an assembly type. In the example shown in FIG. 6, the front and rear cross members 17a and 17b that connect the left and right sides have a box-shaped cross section, and the left and right vertical members 18a and 18b that connect the front and rear cross members 17a and 17b near the center also have a box-shaped cross section. Is becoming However, the longitudinal members 18a and 18b are often open cross sections such as an I-shaped cross section.

7 and 8 show cross sections of the cross members 17a and 17b in the vicinity of the joint with the track frame 7, the cross members 17a and 17b have cross sections of the upper flange 19, the outer web 20, and the inner web. 21 and a lower flange 12a, which are integrated by welding.

[0005]

[Problems to be solved by the device]

 However, as shown in FIG. 9, when the hydraulic excavator 1 excavates and takes in the earth and sand, the connecting portion between the cross member farther from the load and the track frame 7 is as shown in FIG. On the contrary to the compression side shown in FIG. 7, a load P acts in a direction in which they are separated from each other, that is, in a tension direction. Therefore, there is a problem that out-of-plane bending stress is generated in the welded joints of the lower flange 12a and the inner web 21 and the outer web 20 and the fatigue strength is reduced. The present invention has been made in view of the above-mentioned circumstances, and provides a car body of a lower traveling body of a construction machine in which the main frame forming the car body and a cylinder provided thereon are integrated as much as possible to improve strength. To do.

[0006]

[Means for Solving the Problems]

 According to the present invention, a main frame is formed by a lower flange formed of a single plate and an integrally molded upper member that is welded so as to be laminated on the lower flange, and a track frame is formed on both left and right sides of the main frame. The upper member and the lower flange communicate with each other through a coupling hole for fastening with a bolt, and a cylinder is welded to the center of the upper surface of the upper member. The cylinder and the cylinder are integrally molded.

[0007]

[Action]

 By opening the bolt holes at the joint between the car body and the track frame in the upper part of the main frame and the lower flange, the bending load on the tightening bolts is reduced and the fatigue strength is reduced due to the local bending load. Prevent.

[0008]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view of a car body showing an example of the present invention. FIG. 2 is a perspective view of a car body showing another embodiment of the present invention.

In FIG. 1, a car body 8 is composed of a cylinder 10 supporting a slewing bearing 4 (FIG. 4), a lower flange 12 of a main frame 11 and an upper member 13 of the main frame 11, each of which is welded 10a, 13a.

The lower flange 12 has a welded structure in which a single plate is serpined or partially machined. The upper member 13 is integrally formed by pressing a normal steel plate or a normal cast steel, or preferably by a high tensile steel plate or a high tensile strength cast steel. The upper member 13 is welded 13 a so as to overlap the upper portion of the lower flange 12. The upper member 13 of the main frame 11 is preferably provided with a counterbore, and a connecting hole 22 for connecting with the track frame 7 by a bolt 9 is formed therethrough together with the lower flange 12.

Further, as shown in FIG. 2, when the upper member 13 of the main frame 11 of the car body 8 is made of cast steel, the upper member 13 can be cast integrally with the cylinder 10 that supports the slewing bearing 4.

[0012]

[Effect of the device]

 Since the cross member and the vertical member do not have a box-shaped cross section due to the welded structure as in the conventional case but have a welded structure of the upper member and the lower flange, the structure is simple, and the number of manufacturing steps can be reduced. Also, by making the bolt holes, which are the connecting holes between the car body and the track frame, open in the upper member and the lower flange of the main frame, the bending load on the bolts is reduced and the local bending is performed. Fatigue strength is prevented from decreasing due to load.

Further, when the cylinder and the main member of the main frame are integrally formed instead of being welded, the connection between the cylinder and the upper member is strengthened, and the fatigue strength can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a car body showing an embodiment of claim 1 of the present invention.

FIG. 2 is a perspective view of a car body showing an embodiment of claim 2 of the present invention.

FIG. 3 is an overall side view of a crawler type hydraulic excavator.

FIG. 4 is a perspective view of a slewing bearing and a hydraulic motor.

FIG. 5 is a perspective view of a conventional base frame.

FIG. 6 is a plan view of a conventional base frame.

FIG. 7 is a vertical cross-sectional view showing a compression side in the vicinity of a joint portion of a conventional cross member with a track frame.

FIG. 8 is a vertical cross-sectional view showing a tension side in the vicinity of a joint portion of a conventional cross member with a track frame.

FIG. 9 is a side view showing excavation work by a hydraulic excavator.

[Explanation of symbols]

 1 Hydraulic excavator 2 Upper revolving structure 3 Lower traveling structure 6 Base frame 7 Track frame 8 Car body 9 Bolt 10 Cylinder 10a, 13a Welding 11 Main frame 12 Lower flange 13 Upper member 22 Coupling hole

Claims (2)

[Scope of utility model registration request] 1. A main frame is formed by a lower flange formed of a single plate and an integrally molded upper member that is welded so as to be stacked on the lower flange, and track frames are formed on both left and right sides of the main frame. A connecting hole for fastening with a bolt is communicated between the upper member and the lower flange, and a cylinder is welded to the center of the upper surface of the upper member. Car body of the body. 2. The car body of the undercarriage of a construction machine according to claim 1, wherein the upper member and the cylinder are integrally molded.