JP2002146831A - Lower frame for construction equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the local deformation of a side frame in a lower frame for construction equipment to improve the durability of the lower frame by smoothly transmitting the load received from a center frame during an excavating work to the whole side frame. SOLUTION: This lower frame 9 for construction equipment comprises the center frame 2 having a cylinder 3 for mounting a rotating bearing in the center and four leg parts 4, 4, 4 and 4 having webs 5 radially protruded from the cylinder 3; and side frames 10 and 10 arranged on both sides of the center frame 2 to place the center frame 2 and having bulkheads 11 for enhancing the torsional rigidity in the inner part. The webs 5 provided on the center frame 2 are arranged so as to be flushed with the bulkheads 11 of at least one position within the side frames 10 and 10 to support the load applied to the web 5 by these bulkheads 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lower frame of a construction machine, and more particularly to a lower frame of a construction machine for improving durability of a lower frame of a construction machine such as a hydraulic shovel.

[0002]

2. Description of the Related Art A conventional lower frame of a construction machine of this type will be described with reference to FIGS. 2 and 3, reference numeral 1 denotes a lower frame of a construction machine. The lower frame 1 is provided with a center frame 2 at a center portion, and the center frame 2 has a slewing bearing (not shown) at the center portion. A cylinder 3 for mounting is provided, and four legs 4, 4, 4, 4 are provided radially from the cylinder 3. And the legs 4,
4, 4, 4 project from the cylinder 3 and the legs 4,
, 4 and 4, and upper plates 4a, 4a, 4 provided above and below the webs 5, 5,.
a, 4a and lower plates 4b, 4b, 4b, 4b. The lower ends of the webs 5, 5,... Are obliquely notched to form locking portions 5a, 5a,.

Further, side frames 6 and 6 are provided at both ends of the center frame 2 for mounting the center frame 2, and the webs 5 and 5 are provided inside the side frames 6 and 6. A plurality of partition walls 7, 7 for increasing the torsional rigidity of the side frames 6, 6 are perpendicular to the longitudinal direction of the side frames 6, 6 near the contact positions of the locking portions 5a. It is provided in.

[0004] When the center frame 2 is mounted on the side frames 6, the locking portions 5 of the webs 5 provided on the center frame 2 are provided.
a, 5a are brought into contact with the upper plates 8, 8 of the side frames 6, 6, and the center frame 2 is mounted on the side frames 6, 6. Then, the load applied to the center frame 2 is transferred from the locking portions 5a, 5a.
8 and is supported by the side frames 6, 6 reinforced by the partition walls 7, 7,.

However, during the excavation operation, the side frames 6 are connected to the webs 5 of the center frame 2.
May receive a heavy load locally,
High stress is generated in the vicinity of the end 8a of the upper plate 8 of the side frame 6 where the end of the locking portion 5a of the web 5 contacts, and the end 8a may be locally deformed S as shown in FIG. there were. The deformation S occurs because the transmission of the force from the web 5 to the partition 7 is not performed smoothly because the web 5 and the partition 7 are not in the same plane.

Therefore, in the lower frame of the construction machine, the load received from the center frame during the excavation work is smoothly transmitted to the entire side frame, thereby preventing local deformation of the side frame and improving the durability of the lower frame. Therefore, a technical problem to be solved arises in order to improve the problem, and an object of the present invention is to solve this problem.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been proposed to achieve the above-mentioned object, and a cylinder for mounting a slewing bearing is disposed at a center portion, and a web is radially formed from the cylinder. A center frame provided with four legs projecting therefrom, and disposed at both ends of the center frame for mounting the center frame;
In a lower frame of a construction machine comprising a side frame provided with a partition for increasing torsional rigidity therein, the web provided on the center frame and at least one partition in the side frame are the same. An object of the present invention is to provide a lower frame of a construction machine arranged so as to be in a plane and configured to support a load applied to the web by the partition.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIG. For convenience of description, the same components as those of the conventional example are denoted by the same reference numerals, and description thereof will be omitted.

In the drawing, reference numeral 9 denotes a lower frame of a construction machine. The lower frame 9 comprises a center frame 2 at a central portion and side frames 10 and 10 arranged at both ends of the center frame 2. Frame 10,
, Provided at least one of the bulkheads 1 that are locally susceptible to load during excavation work.
Are arranged in the same plane as the webs 5, 5,... Provided on the center frame 2.

When the side frame 10 receives a load from the web 5 of the center frame 2 during the excavation operation, the side frame 10 is susceptible to the load.
Is arranged in the same plane as the web 5, the partition 11 can smoothly transfer the load to the entire side frame 10, and therefore, the side frame 10 The upper plate 8 of the side frame 10 that is entirely elastically deformed by the applied load and abuts the locking portion 5a of the web 5 as in the related art.
The end 8a is not locally deformed.

Also, the structure of the present invention is based on the finite element method (F
EM), the upper plate 8 during excavation work
The stress generated near the end 8a was reduced by about 75% as compared with the structure of the prior art.

The present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

[0013]

As described in detail in the above embodiment, the present invention relates to a lower frame of a construction machine comprising a center frame and side frames disposed at both ends of the center frame. Since the web provided on the frame and at least one partition in the side frame are arranged so as to be in the same plane, and the load applied to the web is configured to be supported by the partition, the web is received from the web. The load can be smoothly transmitted to the entire side frame by the partition wall, and local deformation of the upper plate end of the side frame can be prevented, so that the durability of the lower frame can be improved. It is an invention which has a remarkable effect.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is a plan view of a lower frame of a construction machine.

FIG. 2 is a perspective view of a lower frame of a construction machine, showing a conventional example.

FIG. 3 shows a conventional example, and is a plan view of a lower frame of a construction machine.

FIG. 4 shows a conventional example, and is a partial front view of a side frame.

[Explanation of symbols]

 2 Center frame 3 Cylinder 4 Leg 5 Web 9 Lower frame 10 Side frame 11 Partition wall

Claims (1)

[Claims] A center frame provided with four legs by projecting a web radially from the cylinder, the center frame being provided with a cylinder for mounting a slewing bearing at the center; A lower frame of a construction machine, which is provided at both ends of the center frame for mounting and a side frame provided with a partition wall for increasing torsional rigidity inside the lower frame. Wherein the web and at least one partition in the side frame are arranged so as to be in the same plane, and a load applied to the web is supported by the partition. flame.