JPH072490A - Counter weight device for construction machine - Google Patents

Abstract

PURPOSE:To prevent damage in the point end part of a screw part of a mounting bolt for connecting a counter weight to a main frame. CONSTITUTION:A counter weight 3 is fastened to the rear part of a main frame 2a of a turn unit by a mounting bolt 4 inserted in a perpendicular direction to the counter weight 3 and the main frame 2a and by a nut 8 fitted into a screw part of the mounting bolt 4. A counterbore 3a of depth, where a top end of the screw part of the mounting bolt 4 and the nut 8 are housed in the counter weight 3, is provided around a bolt hole part in a counter weight lower surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a counterweight device installed at the rear of a revolving structure of a construction machine.

[0002]

2. Description of the Related Art FIG. 4 is a side view showing a main body of a crawler crane. A revolving structure 2 is rotatably mounted on a traveling body 1 of an endless track type by means of revolving wheels. A counterweight 3 is installed at the rear of the unit 2.

Next, a conventional counterweight device for fastening the counterweight 3 to the main frame of the revolving unit 2 by inserting a mounting bolt in the vertical direction will be described with reference to FIGS. 4 to 6.

Bolt holes are provided in the main frame 2a of the revolving structure 2 and the counterweight 3 in the vertical direction.
Are inserted into the holes, the counterweight 3, and the bolt holes of the main frame 2a. A flat washer 6, a spring seat 7, and a nut 8 are fitted into the threaded portion of the mounting bolt 4 protruding from the main frame 2a. That is, by tightening the nut 8, the counterweight 3 is fastened to the main frame 2a.

[0005]

The counterweight 3 is basically composed of a mounting bolt 4 and a nut 8 for the main frame 2.
Since it is fastened to a, in order to maintain the tightening force,
It is necessary that the threaded portion of the mounting bolt 4 protrudes from the nut 8 to some extent. Further, the counterweight 3 includes a frame having a welding plate structure, a frame made of casting, and the like.
In any case, the tolerance of the height dimension of the counterweight 3 tends to be large, and it is necessary to allow the length of the mounting bolt 4 to have some margin. Therefore, depending on the manufacturing conditions of the counterweight 3, the threaded portion of the mounting bolt 4 often projects from the nut 8. Therefore, when an operation such as turning is performed in a work place where there is an obstacle that is slipping above the ground level of the lower surface of the counterweight 3, the nut 8
This causes a problem that the threaded portion of the mounting bolt 4 protruding from the contact with an obstacle may be damaged. If the screw portion is damaged, the nut 8 may be galled or the counterweight 3 may not be fastened.

Further, when fixing the counterweight 3, the operator first screws the nut 8 into the tip of the threaded portion of the mounting bolt 4, but the distance between the ground and the lower surface of the counterweight 3 is generally about the person's height. Since the work posture of the worker is poor, the protrusion of the other mounting bolt 4 is neglected in order to pay attention only to screwing in, and in the worst case, the worker's head hits the screw portion to cause injury. There is also a risk of being invited. That is, it is one of the causes for giving the worker a feeling of anxiety about work.

An object of the present invention is to provide a counterweight device which can easily eliminate the above-mentioned drawbacks.

[0008]

SUMMARY OF THE INVENTION A counterweight device of the present invention is a mounting bolt in which a counterweight installed in the rear portion of a main frame of a revolving structure is vertically inserted into the counterweight and the main frame, and a screw portion of the mounting bolt. In a counterweight device for construction machinery that is fastened to the main frame with a nut that is fitted into the main frame, provide a counterbore with a depth that allows the tip of the mounting bolt thread and the nut to fit inside the counterweight around the bolt hole on the bottom surface of the counterweight. It is characterized by being provided.

[0009]

The tip of the threaded portion of the mounting bolt is protected by the counterweight, so damage can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIGS.
Will be described. In these figures, FIGS.
The same components as those are indicated by the same reference numerals.

The lower surface position of the counterweight 3 is set lower than the tip of the threaded portion of the mounting bolt 4 protruding from the main frame 2a. A counterbore 3a is provided around the bolt hole of the counterweight 3. Figure 1
As shown in, the tip end of the threaded portion of the mounting bolt 4 and the nut 8 that fasten the counterweight 3 to the main frame 2 a are set inside the counterweight 3. The size and shape of the spot facing 3a may be arbitrary, but it is necessary to take into consideration that at least the tightening tool for the nut 8 is inserted and the sitting property is not deteriorated when the counterweight 3 alone is placed on the ground or the like. The depth of the spot facing 3a is
Counterweight 3 from the tip of the thread of the mounting bolt 4
It may be set so that the lower surface of is low.

In addition, with the head of the mounting bolt 4 facing down,
Apply a detent 5 to the lower surface of the main frame 2a, and attach the bolts 4 to the bolt holes of the main frame 2a and the counterweight 3.
Through the top of the counterweight 3, attach the plain washer 6 and the spring washer 7 and fasten them with the nut 8.
The threaded portion of the counter weight is on the upper side of the counterweight 3 so that the damage can be prevented.
Considering that the tightening work with and is performed on the counterweight 3 and the tightening must be performed with a high torque, the work space is narrow, the work is performed at a high place, and this means involving danger is not common.

[0013]

According to the present invention described above, since the tip end of the threaded portion of the mounting bolt is protected by the counterweight, damage can be prevented, and when the nut is tightened by the tightening tool, It is possible to avoid a collision between the head and the tip of the mounting bolt. In addition, by hiding the protruding portion of the mounting bolt, it is possible to eliminate the anxiety of the operator at hand and improve the design aesthetics of the construction machine.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention,

FIG. 2 is a bottom view of the counterweight shown in FIG. 1 taken along line AA,

3 is a sectional view taken along line BB of FIG.

FIG. 4 is a side view showing a main body of a conventional crawler crane,

5 is a plan view seen from the line CC of FIG. 4,

FIG. 6 is a cross-sectional side view showing a conventional counterweight device.

[Explanation of symbols]

 2 Revolving structure 2a Main frame 3 Counterweight 3a Counterbore 4 Mounting bolt 5 Anti-rotation 6 Plain washer 7 Spring washer 8 Nut

Claims (1)

[Claims] 1. A construction machine in which a counterweight installed at a rear portion of a main frame of a revolving structure is fastened to the mainframe by a mounting bolt vertically inserted into the counterweight and the main frame and a nut fitted into a thread portion of the mounting bolt. In the counterweight device, the counterweight device is provided around the bolt hole on the lower surface of the counterweight with a counterbore having a depth such that the tip of the threaded portion of the mounting bolt and the nut can be accommodated in the counterweight.