JP2001049695A - Revolving frame of construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely fix a position between the rear end part of a vertical plate and a bottom plate for a long time. SOLUTION: A non-welded part 27 is formed between the rear end part of a verical plate 21 and a bottom plate 20. A position between the rear end part of the vertical plate 21 forming a non-welded part 27 and the bottom plate 20 is fastened by a bolt 28 and a nut 29. Hence, when an impulsive force acts from a counter weight 5 attached to the rear end side of the bottom place 20 to the bottom plate 20 during an excavating work by a hydraulic shovel, this force can be transmitted from bottom plate 20 to the rear end part of the vertical plate 21 through the bolt 28 and the nut 29. In this case, as there is no welded part easily broken by stress concentration, between the rear end part of the vertical plate 21 and the bottom plate 20, the position between the rear end part of the vertical plate 21 and the bottom plate 20 can be securely fixed by the bolt 28 and the nut 29 for a long time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a revolving frame of a construction machine suitably used for a construction machine such as a hydraulic shovel.

[0002]

2. Description of the Related Art Generally, construction machines such as hydraulic excavators are
The vehicle includes a lower traveling body, an upper revolving body rotatably mounted on the lower traveling body, and a working device provided on the front side of the upper revolving body so as to be capable of elevating. And the upper revolving structure includes a revolving frame, and on the revolving frame,
A cab that defines an operator's cab, a building cover that houses a motor and the like, a counterweight, and the like are provided.

[0003] Generally, a revolving frame of a construction machine according to the prior art of this kind is connected to a main frame extending in the forward and rearward directions and a plurality of projecting beams on both the left and right sides of the main frame. And left and right side frames. The main frame that constitutes the revolving frame includes a flat bottom plate and a pair of left and right vertical plates extending forward and rearward along the bottom plate. The front end of each vertical plate is a bracket for a working device, and a counterweight is attached to the rear end of each vertical plate.

In the above-described conventional hydraulic excavator, the turning radius of the upper swing body is determined by the rear end of the counterweight. Therefore, when the upper swing body is swung at a narrow work site, an operator in the cab needs to operate. It is necessary to confirm that the counterweight does not come into contact with an obstacle or the like, which causes a problem that the burden on the operator increases.

On the other hand, a small turning radius from the turning center of the upper revolving structure to the rear end of the counterweight is reduced so that the rear end of the counterweight does not protrude rearward from the lower traveling structure. Hydraulic excavators of this type are known. In this type of excavator of the small turning type, in order to shift the mounting position of the counterweight forward,
For example, it has been considered that the length of the left and right vertical plates is reduced, and the counterweight is directly attached to the rear end of the bottom plate constituting the main frame.

[0006]

However, when the counterweight is attached to the rear end of the bottom plate constituting the revolving frame, there are the following problems.

That is, between the bottom plate constituting the main frame and the left and right vertical plates, a portion between the front end and the rear end of the vertical plate is usually welded to the bottom plate over the entire length. Has become. Therefore, when excavating a hydraulic excavator or the like, when an impact force is applied to the bottom plate by the load of the counterweight attached to the rear end side of the bottom plate, the force is applied to the rear plate from the bottom plate via the welded portion. It will be transmitted to the end side.

In this case, since the rigidity of the vertical plate is greater than that of the bottom plate, it is difficult for the force to be transmitted from the bottom plate to the rear end of the vertical plate.
There is a problem in that stress concentrates on the welded portion between the rear end side of the vertical plate located near the counterweight and the bottom plate, so that the welded portion is easily damaged.

In order to remedy such a drawback, for example, a method of enlarging a weld bead formed on a welded portion between the rear end of the vertical plate and the bottom plate, and a method of increasing the build-up of the weld bead formed on the welded portion between the rear end of the vertical plate and the bottom plate. Adopting a structure that reinforces the weld between the rear end of the vertical plate and the bottom plate by a method of providing a reinforcing material between them, etc., further cut out the rear end of the vertical plate to reduce the rigidity of the vertical plate By lowering, it is conceivable to adopt a structure that suppresses concentration of stress on the welded portion between the rear end side of the vertical plate and the bottom plate. However, when these structures are adopted, there is a problem that the number of man-hours for manufacturing the revolving frame is increased and the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and has a pivot frame for a construction machine capable of reliably fixing a rear end of a vertical plate and a bottom plate for a long period of time. It is intended to provide.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a flat bottom plate, and a left and right front end extending along the bottom plate to form a bracket for a working device. The present invention is applied to a revolving frame of a construction machine having a pair of right vertical plates.

A feature of the structure adopted by the invention of claim 1 is that a counterweight mounting portion is provided at a rear end side of the bottom plate, and at least one of the vertical plates is connected to the bottom plate. The gap is welded over substantially the entire length as a welded portion, and a non-welded portion is formed without welding between the rear end portion of the vertical plate and the bottom plate, and between the rear end portion of the vertical plate and the bottom plate. Is that the non-welded portion is fastened using fastening means.

[0013] With this configuration, the rear end of the vertical plate and the bottom plate are fastened using the fastening means.
When an impact force acts on the bottom plate from the counterweight attached to the bottom plate, the force can be transmitted from the bottom plate to the rear end of the vertical plate via the fastening means. For this reason, it is not necessary to provide a welded portion that is easily damaged by the concentration of stress between the rear end side of the vertical plate and the bottom plate, and it is possible to securely fix the rear end side of the vertical plate and the bottom plate. .

According to a second aspect of the present invention, each of the vertical plates is provided so as to be offset to one side in the left and right directions with respect to an imaginary line before and after passing through the center of rotation. An upper flange for reinforcement is fixedly provided on the upper end side of the vertical plate disposed on the side closer to the front side from the middle part in the front and rear directions to the rear end side, and the fastening means is provided behind the upper flange. The configuration is provided between the end and the bottom plate.

[0015] With this configuration, the strength of the vertical plate, which is arranged closer to the center of rotation of each vertical plate, can be increased by the upper flange, and the upper flange can be used by utilizing the upper flange. The rear end and the bottom plate can be fastened by fastening means.

According to a third aspect of the present invention, between the upper flange and the bottom plate, the fastening means is inserted on the inner peripheral side, the upper end portion abuts the lower surface of the upper flange, and the lower end portion contacts the upper surface of the bottom plate. The configuration is such that a pipe body to be in contact is provided.

[0017] With this configuration, when the upper flange and the bottom plate are fastened by the fastening means, the upper flange and the bottom plate are integrated via the pipe body. It can be firmly fastened to the bottom plate.

According to a fourth aspect of the present invention, the fastening means includes a bolt having a head and a nut screwed to the bolt.

With this configuration, the rear end of the vertical plate and the bottom plate are connected to each other with the bolt head in contact with one of the rear end of the upper flange and the bottom plate and the nut in contact with the other. The interval can be concluded.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a swing frame of a construction machine according to the present invention will be described below with reference to FIGS. .

In FIG. 1, reference numeral 1 denotes a lower traveling body of a hydraulic shovel, and 2 denotes an upper revolving body mounted on the lower traveling body 1 so as to be pivotable.
And a cab 3 provided on the revolving frame 12 and defining a cab, a building cover 4 for accommodating a motor and the like, a counterweight 5, and the like.

The revolving frame 12 of the upper revolving unit 2
Is provided with a turning device 6 between itself and the lower traveling structure 1. The turning device 6 causes the upper turning structure 2 to turn about a turning center O. Here, the counterweight 5 is disposed at a position where its rear end face does not protrude rearward from the lower traveling structure 1, and the radius from the turning center O of the upper revolving structure 2 to the rear end face of the counterweight 5 is R. The rear end face of the counterweight 5 is formed to be curved in an arc shape so as to be accommodated in the virtual circle 7 having the radius R.

Reference numeral 8 denotes a working device disposed at the front of the upper revolving unit 2 so as to be able to move up and down. The working device 8 includes a boom 9, an arm 10, a bucket 11, and the like, and performs excavation work of earth and sand. It is.

Here, the cab 3 is formed wide so as to enhance the livability and operability of the operator who operates the hydraulic shovel, and is provided with a large space at the left front portion of the upper swing body 2. For this reason, the boom 9 and the like of the working device 8 are shifted to the right from the center of the upper revolving unit 2 by the width of the cab 3 as shown in FIG. It is arranged at a position offset to the right by a certain dimension with respect to AA.

Reference numeral 12 denotes a revolving frame of the upper revolving unit 2, and the revolving frame 12 is, as shown in FIGS.
A main frame 13 extending in the front and rear directions, and a left projecting beam 14 projecting leftward from the main frame 13;
15, right overhanging beams 16 and 17, which also extend rightward from the main frame 13, and left overhanging beam 1.
The left side frame 18 joined to the front ends of the front and rear sides 4 and 15 and extending in the front and rear directions.
And a right side frame 19 joined to the front end of the front frame 17 and extending in the front and rear directions.

Reference numeral 20 denotes a flat bottom plate that constitutes the main frame 13 together with vertical plates 21 and 22 described later.
Is formed of a thick steel plate. Here, the bottom plate 20
On the rear end side, four weight mounting seats 20A, 20B, 20C, and 20D are provided apart from each other in the left and right directions. On each of these weight mounting seats 20A to 20D, as indicated by a two-dot chain line. The counter weight 5 is attached to the. The weight mounting seat 20B of the bottom plate 20 is also provided.
As shown in FIG. 6, a bolt insertion hole 20E for inserting a bolt 28 to be described later is formed at a position in the vicinity of.

Reference numerals 21 and 22 denote a pair of left and right vertical plates extending forward and backward along the bottom plate 20, respectively.
2 is an imaginary line A- passing through the turning center O of the turning frame 12;
A is provided offset to the right by a certain dimension with respect to A, the left vertical plate 21 is disposed on the side near the turning center O,
The right vertical plate 22 is disposed on the side away from the turning center O. The load from the counterweight 5 acting on each of the vertical plates 21 and 22 is large in the vertical plate 21 near the turning center O and small in the vertical plate 22 far from the turning center O.

The left vertical plate 21 has a front vertical plate 21A fixed to the upper surface of the bottom plate 20 by welding over the entire length.
And a bolt 28 on the upper surface of the bottom plate 20 as described later.
The front end of the front vertical plate 21A is a bracket 21C that supports the base end of the boom 9 so as to be able to move up and down.

On the other hand, the right vertical plate 22 is constituted by a front vertical plate 22A and a rear vertical plate 22B fixed to the upper surface of the bottom plate 20 over the entire length by welding, and the front end side of the front vertical plate 22A is a boom 9. The bracket portion 22C supports the base end side of the bracket so as to be able to move up and down.

Reference numeral 23 denotes an upper flange fixed to the upper end of the vertical plate 21 by welding.
Front and rear intermediate portions, for example, front vertical plate 21A and rear vertical plate 2
Extending from the position near the joint with 1B toward the rear end,
It reinforces the vertical plate 21. Here, the rear end 21D of the vertical plate 21 is displaced forward by the dimension B from the rear end 23A of the upper flange 23 as shown in FIG. Further, a bolt insertion hole 23B is formed in the upper flange 23 at a position corresponding to the bolt insertion hole 20E of the bottom plate 20, and a top surface of the upper flange 23 is located near the bolt insertion hole 23B to be described later. An L-shaped detent member 24 for detenting the nut 29 is fixed.

Numeral 25 denotes a welded portion provided between the vertical plate 21 and the bottom plate 20. The welded portion 25 has a dimension from the front end to the rear end of the vertical plate 21, as shown in FIG. In the range of C, it is provided over substantially the entire length of the vertical plate 21. The vertical plate 21 and the bottom plate 20 are fixed to each other by welding in the range of the welded portion 25, and a weld bead 26 is formed in the welded portion 25 as shown in FIG.

Reference numeral 27 denotes a non-welded portion provided between the rear end portion of the vertical plate 21 and the bottom plate 20.
6 where no welding is performed between the base plate 1 and the bottom plate 20, that is, FIG.
Is set in the range of the dimension D from the rear end 23A of the upper flange 23 to the start end of the welded portion 25 shown in FIG. And
The rear end portion of the vertical plate 21 located at the non-welded portion 27 is fixed to the bottom plate 20 by using bolts 28 and nuts 29 constituting fastening means.
It is configured to be fastened.

Reference numeral 28 denotes a bolt as a fastening means for fastening a non-welded portion 27 between the rear end portion of the vertical plate 21 and the bottom plate 20 together with the nut 29. The bolt 28 is a bolt insertion hole from the lower surface side of the bottom plate 20. 20E, pipe body 30, upper flange 2
3 is inserted into the bolt insertion hole 23B. Then, the bolt 28 is screwed onto a nut 29 which is stopped by the rotation stopping member 24 on the upper surface side of the upper flange 23, and its head 28
In the state where A contacts the lower surface of the bottom plate 20 and the nut 29 contacts the upper surface of the upper flange 23, the rear end portion of the vertical plate 21 and the bottom plate 20 are fastened.

Reference numeral 30 denotes a rear end of the upper flange 23 and the bottom plate 20.
And a pipe body having a bolt 28 inserted through the inner peripheral side thereof. The pipe body 30 is not fixed to either the upper flange 23 or the bottom plate 20, and the upper flange When the bottom plate 23 and the bottom plate 20 are fastened, the upper end side contacts the lower surface of the upper flange 23, and the lower end side is the bottom plate 2.
0 is in contact with the upper surface. Thereby, the vertical plate 21
The upper flange 23 and the bottom plate 20 can be integrated via the bolt 28 and the pipe body 30, so that the rear plate of the vertical plate 21 and the bottom plate 20 can be securely fastened. ing.

Reference numerals 31 and 31 denote two brackets which are fixed to the upper surface of the upper flange 23 of the vertical plate 21 so as to be separated from each other in the front and rear directions, and 32 and 32 are separated from the upper surface on the rear end side of the bottom plate 20 by the front and rear directions. A motor and the like (not shown) are mounted on each of the two brackets 31 and 32.

Reference numeral 33 denotes the bottom plate 20 and the side frame 1
8, the cab support frame 33 is provided with a total of four support brackets 34, two of which are fixed to each of the projecting beams 14, 15.
The cab 3 is supported together with.

The turning frame 12 according to the present embodiment has the above-described configuration, and the basic operation of the hydraulic excavator provided with the turning frame 12 is not particularly different from that of the prior art.

However, in the revolving frame 12 according to the present embodiment, a non-welded portion 27 where welding is not performed is provided between the rear end portion of the vertical plate 21 and the bottom plate 20, and the vertical plate serving as the non-welded portion 27 is provided. Bolts 28 between the rear end portion 21 and the bottom plate 20;
It is configured to be fastened using a nut 29. For this reason, when excavating a hydraulic excavator or the like, the counterweight 5 attached to the rear end of the
When an impact force acts on the vertical plate 21, the force can be transmitted from the bottom plate 20 to the rear end portion of the vertical plate 21 via the bolt 28 or the like.

In this case, the rear end portion of the vertical plate 21 and the bottom plate 20
Since there is no welded portion between the bottom plate 20 and the rear end portion of the vertical plate 21 which is easily broken by stress concentration, it is necessary to securely fix the bottom plate 20 with the bolt 28 or the like for a long period of time. Can be. For this reason, for example, a method of increasing the build-up of a weld bead that becomes a weld between the rear end side of the vertical plate and the bottom plate, a method of providing a reinforcing material between the rear end side of the vertical plate and the bottom plate, and the like, There is no need to reinforce the welded portion between the rear end side of the vertical plate and the bottom plate, and the number of manufacturing steps and manufacturing costs of the turning frame 12 can be reduced.

Further, an upper flange 23 is fixedly provided on the upper end side of the vertical plate 21 near the turning center O of the turning frame 12, and a bolt 28 and a bolt 28 are provided between the rear end of the upper flange 23 and the bottom plate 20. Since the fastening is performed using the nut 29, the strength of the vertical plate 21 to which a large load is applied from the counterweight 5 can be increased by the upper flange 23, and the vertical plate 21 and the bottom plate are 20
Can be fastened with a bolt 28 or the like.

Further, the rear end of the upper flange 23 and the bottom plate 2
0, the upper flange 23 and the bottom plate 20 are integrated via the pipe 30 when the upper flange 23 and the bottom plate 20 are fastened with the bolts 28 and the nuts 29. As a result, the rear end of the vertical plate 21 and the bottom plate 20 can be more securely fastened.

In the above-described embodiment, the vertical plate 21
The upper flange 23 is fixedly provided on the upper end of the upper flange 23 so as to extend from the intermediate portion in the front and rear directions toward the rear end.
The case where the bottom plate 20 is fastened between the rear end side of the vertical plate 21 and the bottom plate 20 using bolts 28 and the like inserted in the bolt insertion holes 23B provided in the base plate 3 and the bolt insertion holes 20E provided in the bottom plate 20 is exemplified. ing.

However, the present invention is not limited to this. For example, as shown in a modification shown in FIG.
Are abolished and bolt insertion holes 41 are
A is fixedly provided with a short mounting plate 41 in which A is drilled, and the vertical plate 21 is formed by using bolts 28 and nuts 29 inserted into the bolt insertion holes 41A of the mounting plate 41 and the bolt insertion holes 20E of the bottom plate 20. It is good also as composition which fastens between the rear end side and bottom plate 20.

In the above embodiment, the bolt 2
8, the bolt insertion hole 20E of the bottom plate 20, the pipe body 30,
An example has been described in which the bolt is inserted into the bolt insertion hole 23B of the upper flange 23 and the nut is screwed to the nut 29 on the upper surface side of the upper flange 23. However, the present invention is not limited to this.
For example, a screw hole may be formed instead of the bolt insertion hole 23B of the upper flange 23, and the bolt 28 may be screwed into the screw hole. In this case, the nut 29 and the detent member 24 can be eliminated.

In the above-described embodiment, the pipe 30 is not fixed to either the upper flange 23 or the bottom plate 20. However, the present invention is not limited to this. May be fixed by welding or the like.

In the above embodiment, the bottom plate 20
Left and right vertical plates 21 and 22 extending forward and backward along
Of these, the portion between the rear end portion of the left vertical plate 21 and the bottom plate 20 is a non-welded portion 27, and the vertical plate 21
Bolt 28 and nut 29 between the rear end portion of the
An example is shown in which the fastening is performed by using the following.

However, the present invention is not limited to this. For example, a non-welded portion 51 is also provided between the rear end portion of the right vertical plate 22 and the bottom plate 20 as in another modification shown in FIG. A mounting plate 52 is provided at a rear end portion of the vertical plate 22 that has become the non-welded portion 51,
A configuration may be adopted in which the mounting plate 52 and the bottom plate 20 are fastened using bolts 53 and nuts 54.

In the above-described embodiment, the left vertical plate 21 is constituted by the front vertical plate 21A and the rear vertical plate 21B.
Although the case where the right vertical plate 22 is constituted by the front vertical plate 22A and the rear vertical plate 22B has been described as an example, the present invention is not limited to this, and the vertical plates 21 and 22 are each formed by one vertical plate. You may comprise.

Further, in the above-described embodiment, the rear end face of the counterweight 5 is configured to fit within the imaginary circle 7 having the radius R from the turning center O when the upper turning body 2 turns.
The so-called small backward turning hydraulic excavator was taken as an example,
The present invention is not limited to this, and can be applied to a hydraulic excavator having a normal upper swing body.

Further, in the above-described embodiment, a hydraulic shovel has been described as an example of a construction machine. However, the present invention is not limited to this, and other construction machines such as a wheel-type hydraulic shovel and a hydraulic crane may be used. It can be widely applied to machines.

[0051]

As described above in detail, according to the first aspect of the present invention, at least one of the pair of left and right vertical plates extending in the front and rear directions along the bottom plate, and the bottom plate. Between the rear end portion of the vertical plate and the bottom plate, there is no non-welded portion where no welding is performed, and after the vertical plate that has become the non-welded portion, Since the end part and the bottom plate are configured to be fastened using fastening means,
Even if an impact force acts on the bottom plate from the counterweight attached to the bottom plate, this force can be transmitted from the bottom plate to the rear end of the vertical plate via bolts, and the rear end of the vertical plate and the bottom plate Can be reliably fixed for a long time. Therefore, a welded portion between the rear end of the vertical plate and the bottom plate, which is easily damaged by stress concentration when an impact force acts on the bottom plate, becomes unnecessary, and it becomes unnecessary to reinforce the welded portion. The number of manufacturing steps and manufacturing cost of the revolving frame can be reduced.

According to the second aspect of the present invention, each vertical plate is provided so as to be offset to one side in the left and right directions with respect to an imaginary line before and after passing through the center of rotation. An upper flange is fixedly provided on the upper end side of the vertical plate disposed closer to the center of rotation from an intermediate portion in the front and rear directions toward the rear end side, and fastening means is provided at the rear end of the upper flange. The upper flange is used to increase the strength of the vertical plate located on the side closer to the center of rotation of each vertical plate. The rear end of the plate and the bottom plate can be fastened by fastening means.

According to the third aspect of the present invention, between the upper flange and the bottom plate, a fastening means is inserted on the inner peripheral side, the upper end abuts against the lower surface of the upper flange, and the lower end abuts on the upper surface of the bottom plate. Since the abutting pipe body is provided, when the upper flange and the bottom plate are fastened with bolts, the upper flange and the bottom plate can be integrated via the pipe body. Thereby, the rear end portion of the vertical plate which has become a non-welded portion can be firmly fastened to the bottom plate, and the force acting on the bottom plate from the counterweight can be securely applied to the vertical plate via bolts and pipes. Can be conveyed to the rear end side.

Further, according to the invention of claim 4, since the fastening means is constituted by a bolt with a head and a nut screwed to the bolt, the fastening means is provided at one of the rear end of the upper flange and the bottom plate. With the head of the bolt abutting and the nut abutting the other, the rear end of the vertical plate and the bottom plate can be securely fastened.

[Brief description of the drawings]

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

FIG. 2 is a plan view of FIG. 1 showing an upper swing body and the like of a hydraulic shovel.

FIG. 3 is a plan view showing a turning frame according to the embodiment.

FIG. 4 shows a bottom plate, a vertical plate, a non-welded portion, etc. of the turning frame in FIG.
It is sectional drawing seen from the arrow IV-IV direction in the middle.

FIG. 5 is a plan view showing a bottom plate and each vertical plate constituting the turning frame.

FIG. 6 is an enlarged sectional view of a main part, showing a main part such as a bottom plate, a vertical plate, a non-welded portion, and a bolt in FIG. 4;

FIG. 7 is an enlarged sectional view of a main part at a position similar to FIG. 6 showing a modification of the revolving frame.

FIG. 8 is an enlarged plan view showing a bottom plate and a rear end side of each vertical plate according to another modification of the revolving frame.

[Explanation of symbols]

5 Counterweight 12 Revolving frame 20 Bottom plate 20A, 20B, 20C, 20D Weight mounting seat (Counterweight mounting part) 21, 22 Vertical plate 21C, 22C Bracket part 23 Upper flange 25 Welded part 27, 51 Non-welded part 28, 53 Bolt (Fastening means) 29,54 Nut (fastening means) 30 Pipe body

Claims (4)

[Claims] 1. A revolving frame for a construction machine comprising a flat bottom plate and a pair of left and right vertical plates extending forward and rearward along the bottom plate and having a front end side as a bracket for a working device. A counterweight mounting portion is provided on the rear end side of the bottom plate,
At least one of the vertical plates and the bottom plate are welded as a weld over substantially the entire length thereof, and no welding is performed between the rear end portion of the vertical plate and the bottom plate. A turning frame for a construction machine, wherein a non-welded portion between a rear end portion of the vertical plate and the bottom plate is fastened using a fastening means. 2. Each of the vertical plates is provided so as to be offset to one side in the left and right directions with respect to an imaginary line before and after passing through the center of rotation, and is disposed on a side of each vertical plate near the center of rotation. An upper flange for reinforcement is fixedly provided on the upper end side of the vertical plate from the intermediate portion in the front and rear directions to the rear end side, and the fastening means is provided between the rear end of the upper flange, the bottom plate, The revolving frame of a construction machine according to claim 1, wherein the revolving frame is provided between the revolving frames. 3. A pipe body is provided between the upper flange and the bottom plate, the fastening means being inserted into the inner peripheral side, the upper end portion abutting on the lower surface of the upper flange, and the lower end portion abutting on the upper surface of the bottom plate. The revolving frame of a construction machine according to claim 2, wherein the revolving frame is provided. 4. The revolving frame of a construction machine according to claim 1, wherein said fastening means comprises a bolt with a head and a nut screwed to said bolt.