JP2013199747A - Frame structure and swivel type work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a frame structure capable of preventing a weld zone at an abutting portion between a plurality of bottom plates welded to a main frame from cracking.SOLUTION: A plurality of bottom plates 5a, 5b are extended in a width direction of a main frame 1 formed in an elongated shape, butted in a length direction of the main frame 1, and welded to a lower portion of the main frame 1. The plurality of bottom plates 5a, 5b include bottom plate bodies 51a, 51b which are large enough to project from parts welded to the lower portion of the main frame 1 in the width direction of the main frame 1 and butt-welded while connecting with each other, and projection portions 52a, 52b which are formed projecting integrally from the bottom plate bodies 51a, 51b along an extension of a butt portion 5c of the bottom plate bodies 51a, 51b and butt-welded, respectively. A weld zone 53 is provided from between the two projection portions 52a, 52b positioned at one end of the butt portion 5c to two projection portions (not illustrated) positioned at the other end.

Description

  The present invention relates to a frame structure such as a hydraulic excavator and a crane, and a swing type work machine using the frame structure.

  FIG. 4 shows a main frame 1 as a frame structure located at the center of a swing frame of a hydraulic excavator. The main frame 1 includes a pair of vertical plates 2 and 2 positioned on the left and right sides, and the vertical frames thereof. The swash plate 3 welded between the working device mounting portions located in front of the plates 2 and 2 and the rear plate 4 welded between the rear ends of the pair of vertical plates 2 and 2 are formed in a box shape. Further, a plurality of bottom plates 5a and 5b are stretched between a pair of vertical plates 2 and 2 and welded to the bottom of the main frame 1 between the inner side surfaces of the pair of vertical plates 2 and 2. , 7 are welded, an engine mount 8 is welded to the rear of the main frame 1, and a swivel bearing 9 is welded to the bottom plate 5a.

  The plurality of bottom plates 5a and 5b have their butted portions 5c grooved downward and welded. In the welded portion of this butted portion 5c, the main frame 1 is connected to the weld end of the welding start point and stop point. The acting stress is concentrated, and the fatigue strength at each weld end is weakened, and fatigue failure such as cracking is likely to occur.

  As a means for preventing this type of fatigue failure, it is known to relieve stress concentration on each weld end by shaping the weld end by grinding each weld end. However, there is a problem that the shaping work by the grinder is time-consuming.

  Moreover, as a welding technique for the swivel frame, in order to prevent stress concentration at the welded portion between the vertical plate and the reinforcing plate of the main frame, a part of the reinforcing plate is cut out in an arc shape at a position close to the welded portion so as to bend easily. Thus, a structure in which a concave curved surface portion for stress distribution dispersion is formed in an arc shape is disclosed (for example, see Patent Document 1).

Japanese Utility Model Publication No. 06-087454 (see paragraph [0006] and FIG. 1-2)

  The technique of cutting out a part of the reinforcing plate in an arc shape by the concave curved surface portion of Patent Document 1 applied to the welded portion between the vertical plate and the reinforcing plate is easily welded to the main frame 1. In addition, the method cannot be applied to welding of a butt portion 5c between a plurality of bottom plates 5a and 5b that are welded to each other.

  Therefore, in order to prevent cracks from being generated from the respective weld ends to the welded portion of the butted portion 5c between the bottom plates 5a and 5b welded to the main frame 1, such a troublesome grinder process is used. There is a problem that has to be remodeled.

  The present invention has been made in view of the above points, and a frame structure capable of preventing the occurrence of cracks in a welded portion of a butt portion between a plurality of bottom plates welded to a main frame, and a swivel equipped with the frame structure An object is to provide a mold work machine.

  The invention described in claim 1 includes a main frame formed in an elongated shape, and a plurality of bottom plates that are spanned in the width direction of the main frame and are butted from the longitudinal direction of the main frame and welded to the lower portion of the main frame. A plurality of bottom plates having a size protruding in the width direction of the main frame from a portion welded to the lower portion of the main frame and being butt welded in a mutually continuous state, and these bottom plate bodies Projecting portions that are integrally formed with the same length from the bottom plate body along the extension line of the butting portion and are butt welded, respectively, from the butting portion between each bottom plate body to the butting portion between each projecting portion It is a frame structure provided with a weld formed by butt welding.

  According to a second aspect of the present invention, there is provided a lower traveling body, a swing frame of an upper swing body that is turnably provided on the lower traveling body, a working device mounted on a front end of the swing frame, and a rear end of the swing frame The swivel frame is a swivel work machine comprising the frame structure according to claim 1.

  According to the first aspect of the present invention, the plurality of bottom plates, which are stretched in the width direction of the main frame formed in a long shape and are butted from the longitudinal direction of the main frame and welded to the lower portion of the main frame, From the bottom plate main body welded to the lower portion and projecting in the width direction and butt welded to each other, extending from the bottom plate main body along the extension line of the butt portion of these bottom plate main bodies, and extending over the projecting portion to be butt welded Since the welded part is formed, the welded end points of the welding start point and stop point can be arranged outside the flow of stress generated in each bottom plate body welded to the main frame along the main frame by each projection part. As a result, the stress acting on each of the welded end portions can be relieved, and a crack at the welded portion of the butt portion between the plurality of bottom plates welded to the main frame can be achieved. Generate can be prevented.

  According to the second aspect of the present invention, the swing frame of the upper swing body provided in the lower traveling body so as to be pivotable includes the frame structure according to the first aspect, and a plurality of bottom plates welded to the main frame of the swing frame. Since the occurrence of cracks at the welded portion of the butt portion can be prevented, a swing type work machine with improved durability of the swing frame can be provided.

It is a principal part perspective view which shows one Embodiment of the frame structure which concerns on this invention. It is the top view which expanded a part of structure same as the above. It is a perspective view which shows the turning type work machine provided with the structure same as the above. It is a perspective view which shows the conventional frame structure.

  Hereinafter, the present invention will be described in detail based on the embodiment shown in FIGS.

  As shown in FIG. 3, a hydraulic excavator 11 as a revolving type work machine is provided with an upper revolving unit 13 capable of revolving on a lower traveling unit 12, and a work is performed at the center front end of the revolving frame 14 of the upper revolving unit 13. The device 15 is mounted, the engine 16 is mounted on the rear side of the central portion of the swivel frame 14, the counterweight 17 is mounted on the rear end of the swivel frame 14, and the cab 18 is disposed on one side of the work device 15. A cooling device such as an oil cooler or a radiator is disposed behind the cab 18, and tanks 19 such as a fuel tank and a hydraulic oil tank are disposed on the opposite side of the cab 18 with the work device 15 interposed therebetween. A hydraulic pump to be driven is arranged.

  The working device 15 and the engine 16 are mounted on a main frame located at the center of the revolving frame 14, and the cab 18, a cooling device, and the like are one side frame (not shown) welded to one side of the main frame. The tanks 19 are mounted on the other side frame (not shown) welded to the other side of the main frame.

  FIG. 1 shows a main part of the main frame 1 located at the center of the revolving frame 14. Since the overall configuration of the main frame 1 is the same as that of the conventional structure shown in FIG. 4, the same parts as those in the conventional structure shown in FIG.

  In the frame structure 21 shown in FIG. 1, the main frame 1 is formed in an elongated shape in the horizontal direction, and a plurality of bottom plates 5 a and 5 b are spanned in the width direction of the main frame 1. The bottom plates 5a and 5b that are butted together are welded to the lower portion of the vertical plate 2 of the main frame 1, and welded portions 50a and 50b are formed on both sides along the lower portion of the vertical plate 2.

  As shown in FIGS. 1 and 2, each of the plurality of bottom plates 5a and 5b has a size protruding in the width direction of the main frame 1 from a welded portion 50a welded to the lower portion of the vertical plate 2 of the main frame 1. The bottom plate bodies 51a and 51b which are butt welded in a mutually continuous state, and the bottom plate bodies 51a and 51b are integrally projected from the bottom plate bodies 51a and 51b along the extension line of the butted portions 5c of the bottom plate bodies 51a and 51b. Protruding portions 52a and 52b are provided.

  The tips of the protrusions 52a and 52b have the same length and are projected from the bottom plate bodies 51a and 51b so as to be flush with each other and formed in a straight line parallel to the main frame 1.

  FIG. 1 shows only the protrusions 52 a and 52 b on one side of the main frame 1, but similar protrusions are provided on the opposite side of the main frame 1. In FIG. 2, a two-dot chain line A indicates the straight shape of the conventional bottom plates 5a and 5b.

  A welded portion 53 formed by butt welding is provided from the butt portion between the bottom plate bodies 51a and 51b to the butt portion between the projecting portions 52a and 52b.

  In providing this welded portion 53, because the groove processing of the reverse V-groove cross section is continuously performed on the lower side continuously over the entire length of the butted portion 5c extending from the bottom plate main bodies 51a, 51b to the protruding portions 52a, 52b. Welding is started from between the two protrusions 52a and 52b located at one end of the butted part 5c so as to fill the groove processed part, and two protrusions (not shown) located at the other end of the butted part 5c. The welding is finished in between.

  In short, one welding end portion (for example, a welding start point) of the welded portion 53 extends to between the projecting portions 52a and 52b located on one side of the main frame 1 shown in FIGS. The other welding end portion (for example, a welding stop point) is formed so as to extend between projections (not shown) located on the opposite side of the main frame 1.

  Since it is configured in this manner, a plurality of bottom plates 5a and 5b, which are stretched in the width direction of the main frame 1 formed in a long shape and are butted from the longitudinal direction of the main frame 1 and welded to the lower portion of the main frame 1, From the bottom plate main bodies 51a and 51b which are welded to the lower part of the main frame 1 and protrude in the width direction and are butt welded to each other, the bottom plate main bodies 51a and 51b are extended along the extension lines of the butted portions 5c of the bottom plate main bodies 51a and 51b. Since the welded portion 53 is formed over the projecting portions 52a and 52b that are integrally projected from 51b and are butt welded, the bottom plates welded to the main frame 1 along the main frame 1 by the projecting portions 52a and 52b. The welding end portions of the welding start point and the stopping point can be arranged outside the flow of stress generated in the main bodies 51a and 51b, whereby the welded portions at the protruding portions 52a and 52b (from each welding end portion to the butt portion 5c And two-dot chain The stress acting on the intersection of the line A and the vicinity of the intersection) can be relieved, and the occurrence of cracks in the welded portion 53 of the butted portion 5c between the plurality of bottom plates 5a and 5b welded to the main frame 1 can be prevented.

  Furthermore, since the protruding amount of the bottom plate main bodies 51a and 51b protruding outward from the welded portion 50a between the main frame 1 and the bottom plates 5a and 5b can be suppressed, the bottom plate material can be saved and the weight can be reduced.

  Further, a turning frame 14 of an upper turning body 13 provided on the lower traveling body 12 so as to turn is provided with the frame structure 21, and a butted portion 5c between bottom plates 5a and 5b welded to the main frame 1 of the turning frame 14 is provided. Since the occurrence of cracks in the welded portion 53 can be prevented, it is possible to provide the hydraulic excavator 11 with improved durability of the swing frame 14.

  Note that the frame structure 21 of the present invention is not limited to the swing frame 14 of the excavator 11, but other swing work machines such as cranes that need to weld a plurality of bottom plates to the main frame, It can also be applied to vehicle body frames.

  The present invention may be used in industries related to the manufacture and sale of frame structures.

1 Main frame
5a, 5b Bottom plate
5c Butting part
11 Hydraulic excavator as a swivel work machine
12 Undercarriage
13 Upper swing body
14 Swivel frame
15 Work equipment
17 Counterweight
21 Frame structure
51a, 51b Bottom plate body
52a, 52b Protrusion
53 Weld

Claims (2)

A main frame formed in a long shape;
A plurality of bottom plates that are spanned in the width direction of the main frame, butted from the longitudinal direction of the main frame and welded to the lower portion of the main frame;
Multiple bottom plates
A bottom plate body which has a size protruding in the width direction of the main frame from a portion welded to the lower part of the main frame and is butt welded in a continuous state;
Protruding portions that are integrally formed from the bottom plate main body along the extension line of the butting portion of these bottom plate main bodies and are butt welded and formed with equal lengths, respectively.
A frame structure comprising a welded portion formed by butt welding from a butt portion between each bottom plate body to a butt portion between each protrusion. A lower traveling body,
A revolving frame of an upper revolving structure provided to be able to revolve in the lower traveling body,
A working device mounted at the front end of the swivel frame;
A counterweight mounted at the rear end of the swivel frame,
A swivel work machine comprising the frame structure according to claim 1.

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