JPS6119512A - Method of cutting reinforced concrete structure - Google Patents

Abstract

PURPOSE:To enable reinforced concrete to be cut with high efficiency by supplying working liquid between a rotary grinding wheel to which working voltage is applied and a reinforced concrete structure and moving the grinding wheel into contact with the concrete for discharge and electrolysis. CONSTITUTION:An electrode of a power supply unit A is connected to a conductive ring 2 of a disk grinding wheel 1 and reinforcing steel C of a concrete structure M, and working liquid is supplied from an injection nozzle B while the grinding wheel 1 is rotated and moved into contact with the structure M to apply working voltage between the grinding wheel 1 and the structure M. Thus, intermittent discharge phenomenon, electrolysis through the working liquid and mechanical grinding between the grinding wheel 1 and the structure M simultaneously proceed to cut the structure M. Further, the grinding wheel 1 is formed on the circular end surface alternatively with non-conductive polishing strip 5 and conductive strips 4. Thus, the concrete structure in which reinforcing steel is embedded can be cut high efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to composite structures (hereinafter referred to as "concrete structures") made of reinforced Cochley I- reinforced concrete such as reinforced concrete, concrete, and concrete for paved roads, bridge piers, and buildings. This relates to a cutting method.

One of the typical cutting methods for cutting concrete structures is a method using a disc-shaped blade made of sintered diamond chips.

The cutting principle is to repeatedly bring hard particles into contact with the concrete structure and mechanically grind the surface of the concrete structure.

However, such a cutting method has the following problems.

<A> Currently, the processing speed when cutting grooves on paved roads is low at about 50 to 100 cm/min, and the time required for processing is long.

〉Single mechanical degree by repeated contact of abrasive grains
Since it relies only on standard grinding means, there is a limit to its processing capacity.

(c) Cutting concrete alone is a difficult task, but when cutting reinforcing bars, PC steel wires, etc. buried inside a concrete structure at the same time, processing efficiency is significantly reduced.

As a result, the cost of cutting a unit length increases as the expensive blade wears out more.

Furthermore, when cutting reinforcing bars, the blade must be replaced each time, which is time-consuming.

The present invention has been developed in view of the above points, and is capable of cutting efficiently and economically even concrete structures in which reinforcing bars, steel frames, PC steel wires, etc. (hereinafter referred to as "reinforcing bars") are buried. The purpose of this invention is to provide a method for cutting reinforced concrete structures.

Next, an embodiment of the present invention will be described. First, a disk used for cutting according to the present invention will be described.

[Ico disk main body The case where a disk grindstone as shown in FIG. 1 is used will be explained.

This disc grindstone 1 is a disc made by baking and hardening known non-conductive abrasive grains using a suitable binder.

Examples of abrasive grains that can be used include green carborundum, white alundum, pink alundum, silica, diamond, and CBN.

Since the above materials are non-conductive, the disc has no electrical conductivity.

[Opening 1] An energizing ring 2 is provided at the center of the energizing band and abrasive band disc grindstone 1, and a energizing ring 2 is embedded with a radial conductive path 3 from the energizing ring 2.

The conductive path 3 may be a conductive material such as silver or nickel hardened into a rod, wire, or band shape, carbon fiber, conductive plastic, hardened conductive ink or paste, or metal or other material. All conductive paths 3 are electrically connected to the current-carrying ring 2 using a known material.

Further, at the end of each conductive path 3, a conductive band 4 is formed by embedding a conductive material in a direction that crosses the circumferential surface of the disk (hereinafter referred to as "peripheral end surface").

Note that the conductive band 4 may or may not cross the circumferential end surface of the disk.

As a result, non-conductive abrasive grains are exposed as they are on the peripheral surface of the disc grindstone 1 other than the conductive band 4, forming a polishing band 5.

That is, on the peripheral end surface of the disc grinding wheel 1, there is a conductive band 4,
They fly apart while being separated by a non-conductive abrasive band 5,
Or they are formed alternately.

[C] Applied power source The power source applied between the disc grinding wheel 1 and the concrete structure as the workpiece is such that the output waveform is such that, for example, a discharge phenomenon can occur between the grinding wheel 1 and the concrete structure M. As shown in FIGS. 2 to 5, an alternating current, smooth, rectangular or pulsed wave, a distorted wave (alternating current including high frequency), or a combination of two or more of these can be used.

These are appropriately selected and used depending on the exposed interval of the conductive band 4 of the disc grindstone 1, the type of concrete structure M, finishing accuracy, etc.

Next, the cutting method will be explained.

[Connection of the 1 electrode] Connect one of the electrodes pulled out from the power supply unit HA to the disc grindstone 1.
Connect to conductive ring 2, and the remaining electrodes are concrete! Connect to reinforcing bar C buried inside structure M.

[Opening] Electrical discharge machining Next, rotate the disc grinding wheel 1, and while supplying a predetermined machining fluid from the machining fluid injection nozzle B, turn the disc grinding wheel 1 into 7 concrete 1.
・Move closer to structure M.

The conductive band 4 on the peripheral end surface of the disc grindstone 1 repeatedly contacts and separates from the concrete structure M.

Since the concrete structure M is non-conductive, it is generally unthinkable to cause it to be energized, but the present invention breaks the conventional processing common sense and allows the non-conductive concrete structure M to be energized. allowed the condition to occur.

In other words, as a result of repeated intermittent contact at high speed between each conductive band 4 on the circumferential surface of the disc grinding wheel 1 and the concrete structure M, it is thought that an energized state occurs between the two 1 and M due to dielectric action. .

Therefore, an electric discharge phenomenon occurs instantaneously between the disc grindstone 1 and the concrete structure M, and sparks fly.

This spark immediately becomes a thin column of sparks, that is, a flow of electrons with a very high current density, and melts a point on the surface of the concrete structure M.

[C] Electrolytic processing Also, when electricity is applied between the disc grinding wheel 1 and the concrete structure M via a working fluid that also has the characteristics of an electrolytic solution,
Electrolysis progresses and the surface of the concrete structure M is dissolved.

[Nico Machine Grinding Process Immediately after the occurrence of the electric discharge or electrolysis, the grinding progresses by removing the melted portion and oxide film by passing the grinding zone 5 of the disc grindstone 1.

[E] Cutting of reinforcing bars Above, we have discussed cutting of concrete structure M.
The conductive reinforcing bars C can also be easily cut because the three actions of electric discharge, electrolysis, and mechanical grinding described above are repeated alternately.

[F] Other Embodiments In the above embodiments, a case was explained in which a non-conductive concrete structure M was cut using a disc grindstone 1 having alternating conductive bands 4 and abrasive bands 5 on its circumferential surface. ,Besides that,
It is also possible to cut using a known fully energized disc grindstone 1-.

In the case of this embodiment, in order to generate an energized state between the concrete structure M, the power source includes an alternating current, a pulse wave, a composite wave of both, or a composite wave of a direct current and one or more of the above-mentioned champions. Use one that provides an intermittent output waveform.

As a result, as the voltage and current direction change alternately, energized and non-energized states occur intermittently between the disc grinding wheel 1- and the concrete structure M, allowing discharge and electrolysis to occur. .

Furthermore, in addition to these two processes, mechanical grinding is performed by the contact of the abrasive grains constituting the disc grindstone 1, and the cutting progresses with extremely high efficiency.

Since the present invention is as explained above, the following effects can be expected.

Kui〉It is thought that the current-carrying state occurs due to the dielectric effect, but
This makes it possible to process even non-conductive concrete structures by energizing them.

That is, since the three actions of dissolution by electric discharge and electrolysis and mechanical grinding are repeated at high speed, these three actions act synergistically, allowing processing to be performed with a higher efficiency than could be expected with conventional grinding techniques.

<Exposure> With conventional methods, it is extremely difficult to cut composite materials made of different materials, and it is necessary to change the blade depending on the material to be cut.

However, according to the present invention, even with the above-mentioned compound monthly rate, cutting can be performed with high efficiency without replacing the grindstone.

<C> Conventionally, mechanical grinding was simply relied upon, but in the present invention, as mentioned above, electric discharge and electrolytic machining are also performed, and these act synergistically on the workpiece, resulting in a mechanical grinding effect. The abrasive grains are weak, so commercially available and inexpensive abrasive grains can be used as the raw material for the whetstone.

・G2>Also, in the case of grinding by mechanical contact, the grinding wheel wears out depending on the hardness of the workpiece, but in the case of the present invention, the disc grinding wheel mainly contacts the material in a molten state. Therefore, the extent to which the abrasive grains are peeled off by mechanical grinding is extremely small.

Therefore, the wear rate of the grindstone is lower than that of the conventional type.

[Brief explanation of drawings]

Figure 1: Explanatory diagram of the cutting state of concrete structures Part 2~
Figure 5: Illustration of applied power source Figure 6: Illustration of other examples

Claims (3)

[Claims] (1) One of the electrodes is connected to a conductive reinforcing bar buried in a reinforced concrete structure, the other electrode is connected to a conductive grinding wheel, and the grinding wheel is rotated so as to come into contact with the concrete structure, and the grinding wheel is A method for cutting a reinforced concrete structure, characterized in that a machining fluid is supplied between the grinding wheel and the concrete structure, and at the same time a machining voltage that generates electrical discharge and electrolysis is applied between the grindstone and the concrete structure. (2) It is characterized by using a non-conductive disc-shaped grindstone with conductive parts scattered on the peripheral end surface thereof.
A method for cutting a reinforced concrete structure according to claim (1). (3) A method for cutting a reinforced concrete structure according to claim (1), characterized in that the cutting process is carried out using a grindstone that conducts electricity throughout the entire surface and applying an alternating current machining voltage.