Shovel-type construction machine

Abstract

The present invention aims to improve the strength of the portion of the swing frame for attaching the swing motor apparatus while reducing cost. A bottom plate of a swing frame is divided into a center bottom plate segment to which the swing motor apparatus mounting portion is attached, a front bottom plate segment that is positioned to the front side of the center bottom plate segment and to which the center joint mounting portion is attached, and a rear bottom plate segment positioned to the rear side of the center bottom plate segment, wherein: the center, front, and rear bottom plate segments and are formed integrally by welding; and the plate thickness of the center bottom plate segment is thicker than the plate thickness of the front bottom plate segment and the rear bottom plate segment.

Claims

1. A construction machine comprising: an upper swing body having a swing frame; a bottom plate coupled to the swing frame and configured to support the upper swing body on a base, carrier; a swing bearing mounted to the bottom plate, wherein the upper swing body, the swing frame, and the bottom plate are freely rotatable relative to the base carrier via the swing bearing; a center joint disposed at a rotational center of the swing bearing, the center joint configured to supply and drain hydraulic oil between the base carrier and the upper swing body, and a swing motor apparatus positioned rearward of the center joint and configured to drive the swing bearing, wherein: the bottom plate is divided into a center bottom plate segment to which the swing motor apparatus mounting portion is attached, a front bottom plate segment that is positioned forward of the center bottom plate segment and to which the center joint mounting portion is attached, and a rear bottom plate segment positioned rearward of the center bottom plate segment; the front, center, and rear bottom plate segments each having a forward peripheral face and an opposite rearward peripheral face; the front, center and rear bottom plate segments are formed integrally by welding such that the rearward peripheral face of the front bottom plate segment adjoins the forward peripheral face of the center bottom plate segment, and the rearward peripheral face of the center bottom plate segment adjoins the forward peripheral face of the rear bottom plate segment; and the plate thickness of the center bottom plate segment is thicker than the plate thickness of the front bottom plate segment and the rear bottom plate segment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a side view of a hydraulic shovel.

(2) FIG. 2 is a planar view of a swing frame.

(3) FIG. 3 shows: (A), a planar view of a bottom plate; (B), a cross-sectional view of A-A; and (C), a cross-sectional view of B-B.

(4) FIG. 4 is a cross-sectional view of A-A of FIG. 2 in which the swing bearing, center joint, and swing motor mounting apparatus are attached.

(5) FIG. 5 shows: (A), a planar view of the bottom plate of the second embodiment; and (B), a cross-sectional view A-A of (A).

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(6) Embodiments of the present invention are described next, with reference to the drawings. FIG. 1 shows a hydraulic shovel 1 which is an example of a shovel-type construction machine, said hydraulic shovel 1 being characterized in that an upper swing body 4 is supported above a crawler-type bases carrier 2 via a swing bearing 3 so as to be freely rotatable, an operation apparatus 5 for carrying out various operations such as excavation and the like is attached to the front portion of the upper swing body 4, and a counterweight 6 for maintaining balance of the machine body during operation is mounted to the rear portion of the upper swing body 4.

(7) 7 is a swing frame that serves as a base of the upper swing body 4. Said swing frame 7 is configured by: a center frame 7S forming a center portion in the left-right direction; and a pair of left and right side frames 7L, 7R provided on the left and right sides of the center frame 7; wherein, said center frame 7 is further provided with a bottom plate 8 on which the swing bearing 3 is mounted, and a pair of left and right vertical frames 9L, 9R erected on said bottom plate 8. Said pair of vertical frames 9L, 9R extends in the front-back direction, and the front portions thereof form operation apparatus support portions 9La, 9Ra for supporting the base end portions of the operation apparatus 5.

(8) Here, the swing bearing 3 is configured from an outer race 3a fastened to the bottom face of the bottom plate 8 of the swing frame 7 using bolts 10, an inner race 3b fastened to the base carrier 2 with bolts (not shown), and a plurality of bolts 3c threaded in-between the outer race 3a and the inner race 3b; wherein, the inner circumference of the inner race 3b is formed as an inner gear 3d for meshing with a pinion 11a of the swing motor apparatus 11 described below.

(9) 12 is a center joint disposed at the rotational center of the swing bearing 3. The lower-half side of said center joint 12 is disposed so as to penetrate downward through a center joint through-hole 8a opened on the bottom plate 8, and mounted in that state to a center joint mounting portion 8b provided on the bottom plate 8 by using a bolt 13. Further, the supplying and draining of hydraulic oil between the base carrier 2 and upper swing body 4 is performed through the center joint 12.

(10) Still further, the swing motor apparatus 11 is: a motor provided with a speed reducer for driving the swing bearing 3; disposed to the rear side of the center joint 12; and attached to the swing motor apparatus mounting portion 8c of the bottom plate 8 using bolts 14. Yet further still, the pinion 11a coupled to the output axis of said swing motor apparatus 11 passes through the swing motor apparatus through-hole 8d opened on the swing motor apparatus mounting portion 8c and meshes with the above-described internal gear 3d of the swing bearing 3, whereby the it becomes possible for the upper swing body 4 to be rotated with respect to the base carrier 2 on the basis of the forward/reverse driving of the swing motor apparatus 11. Note that, according to the present embodiment, the swing motor is provided in the form of a left and right two-unit swing motor 11 with the left and right units being disposed side-by-side.

(11) Here, the above-described bottom plate 8 is divided into three segments in the front-back direction, including the center bottom plate segment 8X on which the swing motor apparatus mounting portion 8c is provided, the front bottom plate segment 8Y that is positioned to the front side of said center bottom plate segment 8X and on which the center joint is provided, and the rear bottom plate segment 8Z positioned to the rear side of the center bottom plate segment 8X; wherein, the aforementioned bottom plate segments 8X, 8Y, and 8Z are formed integrally by welding. In this case, in order to make the thickness (D1) of the center bottom plate segment 8X a thickness that has a strength capable of withstanding the stress acting on the swing motor mounting portion 8c during rotation, the thickness D1 is set so as to be thicker than the plate thickness of the front and rear bottom plate segments 8Y, 8Z (D2, D3), such that D1>D2, D1>D3, whereby the strength of the swing motor apparatus mounting portion 8c can be secured, and the overall increase in the weight of the bottom plate controlled.

(12) Further, the bottom plate segments 8X, 8Y, 8Z are welded together so that the bottom surface thereof is a uniform surface, whereby the bottom surface of the bottom plate 8 formed by welding together the bottom plate segments 8X, 8Y, 8Z forms the mounting seat surface of the swing bearing 3 (outer race 3a); however, said mounting seat surface for the swing bearing 3 is subjected to a machining process, etc., for smoothing after welding to secure a flatness thereof. Further, the plate thicknesses (D2, D3) of the front and rear bottom plate segments 8Y, 8Z are respectively set so as to secure a required degree of strength thereof; here, in the current embodiment, the plate thickness (D2) of the front bottom plate segment 8Y is set to be slightly thicker than the plate thickness (D3) of the rear bottom plate segment 8Z, but said plate thickness can also be set so as to be the same. Still further, according to the current embodiment, the shape of the front edge portion of the center bottom plate segment 8X is formed so as to be a curved line corresponding to the shape of the front edge portion of the mounting seat surface of the swing motor apparatus mounting portion 8c, in correspondence to which the shape of the rear edge portion of the front bottom plate segment 8Y is also formed in a curved line. In addition, 15 in the drawings is a coupling plate for being coupled between the left and right vertical frames 9L, 9R for reinforcement thereof; wherein, said coupling plate 15 is erected on the center bottom plate segment 8X.

(13) As described above, according to the configuration of the current embodiment: disposed on a bottom plate 8 for configuring a swing frame 7 of an upper swing body 4 are a swing bearing 3, a center joint 12 which is disposed at the rotational center of said swing bearing 3 and performs supplying and draining of hydraulic oil between the base carrier 2 and the upper swing body 4, and a swing motor apparatus 11 which is disposed to the rear side of said center joint and drives the swing bearing; said bottom plate 8 is divided into a center bottom plate segment 8X on which the swing motor apparatus mounting portion 8c is provided, a front bottom plate segment 8Y that is positioned on the front side of said center bottom plate segment 8X and on which the center joint mounting portion 8b is provided, and a rear bottom plate segment 8Z positioned to the rear side of the center bottom plate segment 8X; and the center, front, and rear bottom plate segments 8X, 8Y, 8Z are formed integrally by welding; wherein, the plate thickness of the center bottom plate segment 8X is thicker than the plate thickness of the front bottom plate segment 8Y and the rear bottom plate segment 8Z.

(14) According to the current embodiment of the present invention: by making the plate thickness of the center bottom plate segment 8X, on which the swing motor apparatus mounting portion 8c is provided, so as to be thick, even if the swing motor apparatus is not provided with a reinforcement plate, the strength of the swing motor apparatus mounting portion 8c, which is a portion on which a large amount of stress is concentrated during rotating, can be improved; and by making the plate thickness of the front and rear bottom plate segments 8Y, 8Z positioned to the front and rear of the center bottom plate segment 8X, respectively, thinner than that of the center bottom plate segment 8X, it becomes possible to control the overall increase in weight of the bottom plate 8. Here, in making the plate thickness of the swing motor apparatus mounting portion 8c thick: the bottom plate 8 is divided into a center, front side, and rear side as the three center, front, and rear segments 8X, 8Y, 8Z; the bottom plate segments 8X, 8Y, and 8Z are welded together as an integral unit to form the bottom plate 8; and the plate thickness of the center bottom plate segment 8X, on which the swing motor apparatus mounting portion 8c is provided, is made thicker than the plate thickness of the front bottom plate segment 8Y that is positioned to the front side of the center bottom plate segment 8X and on which the center joint mounting portion 8b is provided, and the plate thickness of the rear bottom plate segment 8Z positioned to the rear side of the center bottom plate segment 8X. Thus, there is no time and effort consumed by processing, and the yield rate of the materials is not caused to deteriorate as in the case where the plate thickness of the swing motor apparatus mounting portion is made thick by subjecting the steel plate member serving as the material for forming the bottom plate to a milling process or the like in order to remove material and thereby make a thin portion and a thick portion thereon, whereby it becomes possible to make the plate thickness of the swing motor apparatus mounting portion 8c thick, and to contribute to keeping the cost down.

(15) Note that the present invention is not limited to the above-described embodiment. According to the above-described embodiment, the shape of the front edge portion of the center bottom plate segment 8X is formed as a curved line corresponding to the front edge portion of the mounting seat surface of the swing motor apparatus mounting portion 8c; however, as per the second embodiment of the bottom plate shown in FIG. 5, the front edge portion of the center bottom plate segment 8X can also be formed in the shape of a straight line. Further, according to the above-described embodiment, dual left-and-right swing motor apparatuses are provided; however, it goes without saying that the present invention can be implemented as an embodiment in which only a single swing motor apparatus is provided.

INDUSTRIAL APPLICABILITY

(16) The present invention is applicable to shovel-type construction machines, such as hydraulic shovels and the like, wherein the bottom plate for configuring the swing frame is provided with a swing motor mounting portion.

REFERENCE SYMBOLS

(17) 1. Hydraulic shovel 2. Base carrier 3. Swing bearing 4. Upper swing body 7. Swing frame 8. Bottom plate 8X. Center bottom plate segment 8Y. Front bottom plate segment 8Z. Rear bottom plate segment 8b. Center joint mounting portion 8c. Swing motor apparatus mounting portion 11. Swing motor apparatus 12. Center joint