JP2003082705A - Turning frame of construction machine and its of manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems wherein overhang beams 21 and 24 for supporting a cab from the under side are formed as beams forming a hollow structure for securing sufficient rigidity for supporting the cab having large weight from the under side, and the hollow structure causes resonance in a certain frequency by the size and a shape, and increases in vibration and noise. SOLUTION: By arranging partition wall members 36A, 36B, 37A, and 37B for defining a plurality of closed spaces S1 to S3, and S5 to S7 in the overhang beams 21 and 24 forming the hollow structure, the size of the closed spaces in the overhang beams 21 and 24 changes, and a resonance causing frequency changes to thereby avoid an overlap of a resonance frequency of the overhang beams and a frequency of the propagating vibration and noise as well as to prevent an increase in the vibration and the noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction machine capable of reducing noise, and more particularly to a swing frame for the construction machine and a method for manufacturing the same.

[0002]

2. Description of the Related Art Generally, construction machines such as hydraulic excavators are
A revolving revolving structure is provided on the traveling structure, and the revolving structure has a revolving frame. A cab that defines a driver's cab, a building cover that houses a prime mover, a counterweight, and the like are provided on the revolving frame (for example, Japanese Unexamined Patent Publication No. Hei 10 (1999) -109242)
-88617 gazette).

The conventional swing frame of this type includes a center frame mounted on a traveling body via a swing wheel, and a left and right sides of the center frame which extend in the front and rear directions. , A right side frame, and a plurality of overhanging beams provided between the center frame and the left and right side frames to join the left and right side frames to the center frame.

Of the plurality of overhanging beams, the overhanging beam for supporting the cab, which supports the cab from the lower side, is formed as a beam having a hollow structure of, for example, a substantially quadrangular shape, and a heavy cab is attached from the lower side. It is configured to ensure sufficient rigidity to support it.

[0005]

By the way, in the above-mentioned prior art, a prime mover for driving a hydraulic source such as a hydraulic pump, a cooling fan driven by the prime mover, a hydraulic motor for swinging, etc. are mounted on a swing frame. Therefore, the prime mover, the cooling fan, the turning hydraulic motor, and the like constantly generate vibration and noise after the engine is started.

Particularly in a hydraulic excavator, the frequencies of the vibration and noise fluctuate depending on the work load and work mode. For example, the turning hydraulic motor is stopped from the stopped state (the number of revolutions is zero) to the maximum. When the frequency is increased or decreased within the range of the number of revolutions, the frequency of vibration and noise fluctuates greatly.

Further, in the hollow structure such as the overhanging beam for supporting the cab, resonance occurs at a certain frequency due to its size and shape, and vibration and noise increase near that frequency. Therefore, due to the hollow structure of the overhanging beam for supporting the cab, resonance occurs inside, and the vibration and noise transmitted to the cab by the vibration and noise generated by the prime mover of the hydraulic excavator, the cooling fan, the hydraulic motor for turning, etc. Is further increased.

On the other hand, measures such as increasing the plate thickness of the overhanging beam to increase the rigidity have been studied. With this method, although the vibration can be suppressed slightly, the resonance frequency does not change, so it is sufficient. Vibration and noise reduction effect cannot be obtained.

On the contrary, a method of making the cross-sectional shape of the overhanging beam smaller can be considered, but in this case, the strength of the overhanging beam is insufficient and the riding comfort of the cab is deteriorated due to twisting due to external force. There is a risk of doing so.

The present invention has been made in view of the above-mentioned problems of the prior art. An object of the present invention is to change the resonance frequency inside the hollow structure by providing a partition member in the overhanging beam for supporting the cab. Another object of the present invention is to provide a swing frame of a construction machine capable of preventing vibration and noise of the cab and a manufacturing method thereof.

[0011]

In order to solve the above-mentioned problems, the present invention provides a center frame comprising a bottom plate and left and right vertical plates erected on the bottom plate, and left and right of the center frame. The left and right side frames located on both sides and extending in the front and rear directions, and the left and right side frames provided between the center frame and the left and right side frames and the bottom plate of the center frame and the vertical plate. It is applied to a swing frame of a construction machine having a plurality of overhanging beams joined to a plate.

A feature of the invention of claim 1 is that, among the plurality of overhanging beams, the overhanging beam for supporting the cab of the construction machine from below is provided with a plurality of closed spaces in the lengthwise direction of the overhanging beam. By providing the partition member that defines the above, it is possible to change the resonance frequency inside the projecting beam and prevent an increase in vibration and noise. By providing the partition member inside the overhanging beam, the rigidity of the overhanging beam can be increased and the riding comfort of the cab can be improved.

According to a second aspect of the present invention, the overhanging beam for supporting the cab has an upper frame member having a U-shaped cross section, and a flat plate-like member joined to a lower surface side of the upper frame member. Configured as a beam with a hollow structure by the lower plate,
By providing the partition member between the upper frame member and the lower plate member, it is possible to change the resonance frequency inside the overhanging beam and prevent an increase in vibration and noise.

Further, according to a third aspect of the present invention, the partition member is formed of a plate member that divides the partition beam vertically and evenly with respect to the length direction, so that the resonance frequency inside the projection beam is increased. It can be changed to prevent vibration and noise from increasing.

Further, a feature of the invention of claim 4 is that the partition wall member is constituted by a plate member that divides the partition beam vertically and evenly into three parts in the extension beam, whereby the resonance frequency inside the extension beam is formed. Can be changed to prevent an increase in vibration and noise.

Further, a fifth aspect of the present invention is characterized in that a cab-supporting overhanging beam which constitutes a revolving frame of a construction machine is provided in an upper frame member having a U-shaped cross section, and a plurality of insides of the overhanging beam are provided. By the manufacturing method in which the partition member that defines the space is welded in advance, and then the lower member is welded, the resonance frequency inside the overhanging beam can be changed to prevent an increase in vibration and noise.

Further, a sixth aspect of the present invention is characterized in that a plurality of closed spaces for preventing vibration and noise increase by changing the resonance frequency inside the cab-supporting beam forming the swing frame of the construction machine are provided. By forming in the beam in the length direction, the resonance frequency inside the cab-supporting overhanging beam can be changed, and vibration and noise can be prevented from increasing.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the swing frame of a construction machine according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, taking as an example the case where the swing frame is applied to a hydraulic excavator.

FIG. 1 shows a hydraulic excavator, in which 1 is a traveling body and 2 is a revolving structure mounted on the traveling body 1 so as to be capable of revolving. The revolving structure 2 is a revolving frame 1 described later.
Have one. 3 is a cab which is located on the left side of the front part on the revolving frame 11 to define an operator's cab, 4 is located on the rear side of the cab 3, a building cover accommodating a prime mover, a hydraulic pump (not shown) and the like, 5 Is a counterweight located on the rear side of the building cover 4 for balancing the weight during work.

Reference numeral 6 denotes a working device provided on the front part of the revolving structure 2 so as to be able to move up and down, and its base end side is pin-connected to boom brackets 13A and 14A shown in FIG.
A boom 7 which is lifted and lowered by a pair of right boom cylinders 7A (only one is shown), and an arm 8 which is pin-coupled to the tip side of the boom 7 and is lifted and lowered by an arm cylinder 8A.
And a bucket 9 as a work tool which is pin-connected to the tip end side of the arm 8 and is rotated by a bucket cylinder 9A. The bucket 9 excavates earth and sand.

FIG. 2 shows the swivel frame 11 of the present invention. The revolving frame 11 is composed of a center frame 15 and a tail frame 16 which will be described later and which are located in the central portion and extend in the front and rear directions, and side frames 19 and 20 which will be described later and which are located on both the left and right sides thereof. There is.

The center frame 15 constitutes the central portion of the revolving frame 11, and is provided with a bottom plate 12 formed in a flat plate shape from a thick steel plate or the like, and is erected on the upper surface side of the bottom plate 12 using welding means. The bottom plate 12 is composed of left and right vertical plates 13 and 14 extending in the front and rear directions.

The front portions of the vertical plates 13 and 14 are left and right boom brackets 13 as bracket portions to which the boom 7 of the working device 6 shown in FIG.
A and 14A. The front end sides of the vertical plates 13 and 14 are left and right cylinder brackets 13B and 14B, and the base ends of the boom cylinder 7A shown in FIG. 1 are rotatably pin-connected to the cylinder brackets 13B and 14B. is there.

The tail frame 16 is the center frame 15
The bottom plate 12 of the center frame 15 and the left and right vertical plates 13, 1 provided on the rear end side of the center frame 15 by means of welding or the like.
It is integrated in 4. Then, on the rear end side of the tail frame 16, left and right weight attaching portions 17 and 18 are provided behind the vertical plates 13 and 14, and the left and right weight attaching portions 17 and 18 have an I-shaped cross section. (I flange structure). Then, the counter weight 5 shown in FIG. 1 is detachably attached to the weight attaching portions 17 and 18 from the upper side.

The side frames 19 and 20 constitute the revolving frame 11 together with the center frame 15, and are formed by using, for example, a D-shaped frame having a D-shaped cross section, and the left and right sides of the revolving frame 11 as shown in FIG. It extends forward and backward on both sides.

In FIG. 2, reference numeral 21 denotes a cab supporting beam provided between the left side frame 19 and the center frame 11, and the left end of the beam 21 is joined to the side frame 19 by welding. The right end is joined to the left boom bracket 13A by welding, and the lower end is welded to the upper surface of the bottom plate 12 or the like.

The overhanging beam 21 has a U-shaped cross section as shown in FIG. The overhanging beam 21 includes front and rear side plate portions 22A and 22B and an upper plate portion 22C.
A hollow box structure having a quadrangular cross section by an upper frame member 22 joined by welding and a flat lower plate member 23 joined by welding to the lower surface sides of the side plate portions 22A and 22B of the upper frame member 22. Formed as a body.

Returning to FIG. 2, reference numeral 24 denotes a cab supporting beam provided between the left side frame 19 and the center frame 11, and the beam 24 is located behind the beam 21 as shown in FIG. The cab 3 shown in FIG. 1 is supported together with the overhanging beam 21 from below. The left end of the overhanging beam 24 is also joined to the side frame 19, and the right end thereof is joined to the left vertical plate 13 and the bottom plate 12 by welding.

The overhanging beam 24 also has a U-shaped cross section as shown in FIG. 5, and the upper frame member 25 and the upper frame member 25 in which the front and rear side plate portions 25A and 25B and the upper plate portion 25C are joined by welding. It is formed as a hollow box structure having a quadrangular cross section by a flat plate-shaped lower plate member 26 joined by welding to the lower surface sides of the side plate parts 25A and 25B of 25.

Further, the overhanging beam 24 is disposed at a position substantially corresponding to the rear end side of the cab 3 shown in FIG. 1, and circular anti-vibration mount mounting holes are provided on both left and right ends of the cab 3 as shown in FIG. 24A and 24B are provided. Vibration mounts (not shown) are provided in the mount mounting holes 24A and 24B, respectively, and the cab 3 is mounted on the overhanging beam 24 via these vibration mounts.

Reference numeral 27 denotes a rear plate provided between the rear end side of the side frame 19 and the tail frame 16. The rear plate 27 connects the weight mounting portion 17 of the tail frame 16 and the side frame 19. .

28 is a cab support frame provided between the front end of the side frame 19 and the overhanging beam 21. The cab support frame 28 is located in front of the overhanging beam 21 as shown in FIG. A horizontal beam portion 29 joined to the front end and extending in parallel with the overhanging beam 21 and a vertical beam portion joined to the bottom plate 12 and the overhanging beam 21 by welding the front end side to the horizontal beam portion 29 and the rear end side to extend parallel to the boom bracket 13A. And the unit 30.

The horizontal beam portion 29 and the vertical beam portion 30 of the cab support frame 28 are cab supports for supporting the cab 3 shown in FIG. 1 from below together with the front side of the side frame 19 and the overhanging beams 21 and 24. Are configured. Further, as shown in FIG. 2, the horizontal beam portion 29 of the cab support frame 28 is provided with circular vibration isolating mount mounting holes 29A and 29B on both left and right ends thereof. And these mount mounting holes 29A, 2
9B are provided with anti-vibration mounts (not shown), and the cab 3 is mounted on the cab support frame 28 via these anti-vibration mounts.

Reference numerals 31, 32, 33, and 34 denote right-hand side extension beams provided between the right-side side frame 20 and the center frame 15, and the extension beams 31, 32, 33, and 3 are provided.
Numeral 4 is provided separately from the front and rear, and connects the side frame 20, the center frame 15, and the tail frame 16 together with the rear plate 35.

FIG. 3 is an enlarged perspective view of a main part of the revolving frame showing the cab support frame and the vertical plates of the center frame, and FIG. 4 is a sectional view of the overhanging beam in FIG.

Here, 36 is a partition member provided in the overhanging beam 21 for supporting the cab. Partition member 36
Is made of a flat plate material as shown in FIG.
Two partition plates 3 so as to divide the inside into three substantially evenly.
It is formed by 6A and 36B.

The partition wall member 36 composed of the partition wall plates 36A and 36B is previously welded to the side plate portions 22A and 22B and the upper plate portion 22C of the upper frame member 22 of the overhanging beam 21,
After that, it is vertically welded to the lower plate member 23. As a result, the partition wall member 36 forms three closed spaces S1, S2, S3 of the same volume in the overhanging beam 21.

As described above, the reason why the three closed spaces are formed is to divide the inside of the overhanging beams 21 and 24 into three by the partition member to change the resonance frequency, and to extend the overhanging beams 21 and 24 during the operation of the hydraulic excavator. This is to prevent an increase in vibration and noise by avoiding overlapping with the frequency of vibration and noise propagated in the 24.

Reference numeral 37 denotes a partition wall member provided in the overhanging beam 24 for supporting the cab via partition plates 38 and 39, and is composed of partition wall plates 37A and 37B. Also,
The partition plates 38 and 39 are arranged in the overhanging beam 24 at positions on the inner side of the mount mounting holes 24A and 24B in the longitudinal direction.

Here, the partition member 37 is composed of partition plates 38, 39.
In parallel with the side plate portion 2 of the upper frame member 25 of the overhanging beam 24.
5A, 25B and the upper plate portion 25C are previously welded, and then vertically welded to the lower plate member 26. And
The partition member 37 forms three closed spaces S5, S6, S7 of the same volume in the overhanging beam 24 between the partition plates 38, 39. The formation of the closed spaces S5, S6, S7 is the same reason as above.

FIG. 5 is a sectional view of the inside of the overhanging beam as seen from the direction of the arrow VV in FIG.

Reference numerals 40, 41, and 42 are undercovers, and of the undercovers 40 to 42, the undercover 40 is used.
Is mounted between the cab support frame 28 and the overhanging beam 21 from below by using bolts or the like, as shown in FIG. In addition, the under cover 41 is provided with the overhang beams 21 and 2.
4 is attached from below with bolts, etc.
2 is attached between the overhanging beam 24 and the rear plate 27 from below with bolts or the like.

Next, the operation of the above-described embodiment of the swivel frame of the present invention will be described.

When traveling the hydraulic excavator at the work site, the vehicle is moved forward or backward by driving the traveling hydraulic motor (not shown) of the traveling body 1. And
When excavating earth and sand or the like, the revolving unit 2 is revolvingly driven on the traveling unit 1 to dispose the working device 6 in an arbitrary direction, and in this state, the boom 7 and the arm 8 are lowered and the bucket is lifted. The excavation work can be performed by rotating the shaft 9.

Here, in the revolving structure 2 of the hydraulic excavator, on the revolving frame 11, the hydraulic pump, the prime mover, the cooling fan,
A turning hydraulic motor and the like are mounted, and they constantly generate vibration and noise after the engine is started.
In particular, the turning hydraulic motor is driven by greatly increasing and decreasing the number of revolutions from the stopped state to the maximum number of revolutions during turning, so that the vibration and noise frequencies fluctuate greatly.

On the other hand, in a closed space such as the overhanging beams 21 and 24 of the revolving frame 11, resonance occurs at a certain frequency due to its size and shape, and vibration and noise increase near that frequency. Those around the frequency where resonance occurs, hydraulic pump, prime mover, cooling fan,
Vibrations and noises are further increased by overlapping the frequencies of vibrations and noises from noise sources such as the turning hydraulic motor.

Therefore, according to the embodiment of the present invention, the partition members 36 and 37 are provided inside the overhanging beams 21 and 24 for supporting the cab.
Is provided, and the closed spaces S1 to S3 and S5 are equally divided into three.
~ S7 is configured.

As a result, the size of the closed space inside the overhanging beams 21 and 24 changes, so that the resonance frequency fluctuates greatly, and it is possible to avoid vibration and overlapping with the sound propagated from the noise source. It is possible to prevent an increase in noise. Further, by equally dividing into three, the resonance frequencies in the respective divided closed spaces can be made the same, and the increase of the resonance frequency due to the increase of the closed spaces can be prevented.

Further, the partition members 36 and 37 can increase the strength of the overhanging beams 21 and 24 to enhance the torsional rigidity and the like, and the riding comfort of the cab 3 can also be improved.

In this embodiment, by dividing the inside of the overhanging beams 21 and 24 into three by the partition members 36 and 37, the vibration and noise sources such as the hydraulic pump, the prime mover, the cooling fan, and the hydraulic motor for turning can be reduced. Although the overlapping with the frequency of the propagating sound was avoided, it is not always necessary to divide it into three, and it is also possible to change it into a suitable division number such as two or four depending on the frequency of the propagating sound.

[0051]

As described above in detail, according to the swivel frame of the present invention, a plurality of closed spaces are defined in the lengthwise direction of the cab supporting beam for supporting the cab of the construction machine from below. Since a partition member is provided, a plurality of closed spaces can be defined in the overhanging beam for supporting the cab. For example, the resonance frequency in the overhanging beam can be compared with the frequency of vibration and noise generated when the construction machine turns. It is possible to avoid overlapping with the vicinity and to prevent vibration and noise from increasing.

That is, even when the hydraulic pump, the prime mover, the cooling fan, the hydraulic motor for turning, etc., mounted on the swing frame become sources of vibration and noise, these vibrations, noise frequencies and resonance frequencies near the inside of the overhang beam are close to each other. It is possible to avoid the overlapping of the cabs and to prevent the vibration and noise of the cab from increasing. The partition wall member can increase the rigidity of the overhanging beam and improve the riding comfort of the cab.

Further, according to the manufacturing method of the present invention, the partition member can be provided in the overhanging beam by welding in order to define a plurality of closed spaces in the overhanging beam, and the manufacturing thereof is simple. .

[Brief description of drawings]

FIG. 1 is a front view showing a hydraulic excavator provided with an embodiment of a swing frame of the present invention.

FIG. 2 is an enlarged perspective view showing a swivel frame in FIG.

FIG. 3 is a perspective view of a main part of a swivel frame showing an enlarged beam and the like in FIG.

FIG. 4 is a partially cutaway plan view showing an overhanging beam and the like in FIG.

5 is a cross-sectional view of an overhanging beam and the like as viewed in the direction of arrow VV in FIG.

FIG. 6 is an enlarged perspective view showing a partition wall member in FIG.

[Explanation of symbols]

1 running body 2 revolving structure 3 cabs 6 Working device 11 swivel frame 12 Bottom plate 13,14 Vertical plate 15 center frame 19,20 Side frame 21,24 Overhang beam for cab support 22,25 Upper frame material 23,26 Lower plate 28 cab support frame 31, 32, 33, 34 Overhang beam 36,37 Partition member 36A-36C, 37A-37C Partition plate (plate material)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Seiichiro Takeshita             Hitachi Construction Machinery Co., Ltd.             Ceremony Company Tsuchiura Factory F-term (reference) 3D003 AA06 BB14 CA01

Claims (6)

[Claims] 1. A bottom plate and a left erected on the bottom plate,
Between the center frame composed of the right vertical plate, the left and right side frames located on the left and right sides of the center frame and extending in the front and rear directions, and between the center frame and the left and right side frames. In a revolving frame of a construction machine, which is provided with the left and right side frames, and a plurality of overhanging beams that join the bottom plate of the center frame and a vertical plate, a cab of the construction machine is a lower side of the plurality of overhanging beams. The overhanging beam for supporting the cab from
A swing frame for a construction machine, wherein a partition wall member that defines a plurality of closed spaces in a length direction is provided in the overhanging beam. 2. The overhanging beam for supporting the cab has a hollow structure with an upper frame member having a U-shaped cross section and a flat plate-shaped lower plate member joined to the lower surface side of the upper frame member. 2. The swing frame for a construction machine according to claim 1, wherein the swing member is configured as a beam, and the partition wall member is provided between the upper frame member and the lower plate member. 3. The swivel frame for a construction machine according to claim 1, wherein the partition wall member is constituted by a plate member that is vertically and evenly divided in the overhanging beam in the extension beam. 4. The swivel frame for a construction machine according to claim 1, wherein the partition wall member is constituted by a plate member that is vertically and evenly divided into three parts in the overhanging beam and is divided into three parts. 5. An extension beam for supporting a cab, which constitutes a swing frame of a construction machine, is provided in an upper frame member having a U-shaped cross section, and a partition wall member defining a plurality of spaces in the extension beam in advance. A method for manufacturing a swing frame of a construction machine, comprising welding and then welding a lower member. 6. A plurality of closed spaces are formed in the overhanging beam in the lengthwise direction thereof to change the resonance frequency inside the overhanging beam for supporting the cab which constitutes the revolving frame of the construction machine to prevent vibration and noise from increasing. A method for manufacturing a swing frame for a construction machine, which is characterized by the above.