JPH0634437Y2 - Concrete filling counterweight - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention relates to a counterweight used in a construction machine such as a power shovel, and more particularly to a counterweight in which a box made of sheet metal is filled with heavy concrete. Is.

(Prior Art) As shown in FIG. 5, a counterweight used for a construction machine such as a power shovel as shown in FIG. 4 is a box formed in advance by sheet metal welding in order to manufacture at low cost. It is manufactured by a process in which cement, ore, iron scrap, and the like are mixed in a, heavy concrete b having a higher specific gravity is poured, and then completely sealed.

Then, in order to particularly improve mass productivity, green concrete is successively poured into previously mass-produced boxes, and the charging port is closed before the concrete dries and hardens to complete the counterweight w.

c shows a cover.

(Problems to be solved by the invention) In the concrete curing process, as shown in FIG. 6, the concrete expands in a wet state and conversely contracts as it dries and hardens.

It is said that the expansion when wet is usually 100 to 200 × 10 ^−6, and if it is kept closed during this time, the internal pressure rises extremely.

This internal pressure is about 0.5 Kg / cm ² , and about 10 is applied to the upper plate that is usually the cover.
Ton's power will be added.

Therefore, a large concentrated stress is applied to the welded portion that constitutes the box, and as shown in FIG.

As a means for preventing the swelling of the filling material inside the counterweight, Japanese Patent Application No. 61-40524 (Japanese Utility Model Application No. 62-154057), which was published in the application before this application, was published after this application.
No.)

This device is designed to prevent the counterweight from swelling and to attach covers, but since the ventilation holes are always in communication with the outside air, there is air circulation instead of complete sealing, and rust inside occurs. It is inevitable that it will be deformed or deformed.

The purpose of this invention is to solve the above problems.

(Means and Actions for Solving Problems) The present invention has been made in view of the above points, and is a position facing the upper air chamber formed in the upper part of the box when pouring fresh concrete into the box. In, in the upper box side wall, a small hole for internal pressure removal is drilled, by eliminating the increase in internal pressure when the fresh concrete is wet, it is possible to close the concrete input port with a cover without waiting for the dry hardening of the concrete, When the product was completed, the small holes were closed with blind plugs, which completely eliminated the occurrence of cracks in the box.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the outline of the main part thereof, in which 1 is a counterweight.

2 is a box, and the concrete intake 3 of this box
Fresh concrete (green concrete) 4 is poured into the box 2.

Reference numeral 5 denotes a small hole for removing the internal pressure provided on the side wall of the box 2 near the upper part of the box, and is provided at a position facing the air chamber 7 at the upper part of the box 2.

6 is a cover.

Since the small holes 5 for removing the internal pressure are provided in this way and the internal pressure does not rise when the ready-mixed concrete 4 is wet, it usually takes 1 week to dry and harden the ready-mixed concrete 4. Without waiting for, ready-mixed concrete 4 as before
Even if the concrete input port 3 is closed by the cover 6 immediately after pouring, the problem that the internal pressure rises is eliminated.

Therefore, the box is free from cracks, and reliable counterweight can be mass-produced.

When the product is completed, the small hole 5 is closed with a blind plug 8, and internal rust due to infiltration of rainwater can be prevented when mounting the counterweight on the vehicle body where concrete is completely dried and hardened.
It also helps prevent bulging of concrete.

(Effect of the Invention) This invention is as described in detail above, that is, since the small hole for removing the internal pressure is pre-drilled in the side wall of the box, the internal pressure does not rise when the ready-mixed concrete is wet, so that the concrete is dried and hardened. Since there is no problem even if the concrete input port is closed by the cover without waiting, there is no chance of crevices in the box, and reliable mass production of counterweight can be performed.

As described above, according to this invention, the counterweight can be prevented from bulging at a low cost, and when the counterweight is completed, the small holes are closed with blind plugs, so internal rust due to infiltration of rainwater and expansion of the concrete after the fact. Swelling due to can be prevented.

[Brief description of drawings]

FIG. 1 is a perspective view of a counterweight according to an embodiment of the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, FIG. 3 is an enlarged view of a portion P of FIG. 2, and FIG. ) And (b) are a top view and a side view of a power shovel to which the counterweight according to the present invention is attached, FIG. 5 is a counterweight of a conventional example, and FIG. 6 is a graph for explaining the relationship between wet-drying and expansion / contraction of concrete. Is. 1 ... Counterweight 2 ... Box 3 ... Concrete inlet 4 ... Green concrete 5 ... Small hole for removing internal pressure 6 ... Cover 7 ... Air chamber 8 ... Blind stopper

Claims (1)

[Scope of utility model registration request] 1. A small hole 5 for removing internal pressure is formed in a side wall of the box at a position facing an upper air chamber 7 formed in an upper part of the box 2 when pouring fresh concrete 4 into the box 2. To cover the concrete inlet 3 with a cover without waiting for the concrete to dry and harden.
A concrete-filled counterweight characterized in that the small hole 5 is closed with a blind plug 8 when the product is completed.