JPS60162602A - Method of cutting concrete containing steel material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for cutting steel-filled concrete such as reinforced concrete and plaster reinforced concrete.

(Problems in the prior art that should be solved by the invention) For the demolition of various concrete structures associated with recent urban redevelopment, and the decommissioning and decommissioning of power generation nuclear reactors that will become a reality in the near future. There is a need to develop a technology that can rationally and effectively cut steel-filled concrete.

By the way, the strength of concrete varies significantly depending on the amount of cement, mixing method, hardening method, etc., but in general, it is strong against compression,
It has the property of being weak in tension and can be treated as a so-called hard and brittle material.In contrast, steel in concrete has high toughness and its elastic energy coefficient is incomparable to concrete. It's reasonably big.

By the way, diamond cutting wheels are effective for cutting hard and brittle materials such as rocks and unreinforced concrete.
When cutting concrete (containing steel), the higher the steel ratio, the more oxidation wear occurs on the diamond abrasive grains due to the cutting heat.Generally, diamond oxidizes around 650℃ and generates cobalt gas and gas, causing a rapid decrease in hardness. ), there was a risk of problems such as eyelids and abrasive grains falling off.

For this reason, it was used to cut reinforced concrete with a small steel content ratio (because the reinforcing bars used were small in diameter), but it was not suitable for cutting steel-framed reinforced concrete containing steel frames with a larger cutting area than reinforcing bars. there were. Further, since cutting is performed only by the diamond cutting wheel while cooling water is poured into the wheel, problems such as poor cutting efficiency and large noise are inevitable.

On the other hand, circular saw blades equipped with carbide tips, cermet tips, etc. as cutting edges have excellent heat resistance compared to diamonds, and their hardness does not decrease up to about 1200℃, so they can be used in steel mills. Although it is widely used in steel mills for high-speed cutting and cutting of steel materials, it has not been used for cutting concrete containing steel materials because it is inferior to diamond in terms of wear resistance.

(Objective of the Invention) The present invention was devised to solve the above-mentioned conventional problems, and uses a circular saw blade in combination with a jet of cutting fluid to effectively cool the cutting edge and improve cutting efficiency. The purpose is to improve the

(Accomplishment of the invention) The method for cutting steel-containing concrete according to the present invention includes jetting a cutting agent (for example, a coolant) to a place extremely close to the cutting action point of a rotating circular saw blade. It is characterized by progressing multiple cuts by cutting traces.

(Example) An embodiment of the present invention will be explained below with reference to FIG.

The method of the present invention makes the most of the advantages of the circular saw blade 1, which is equipped with a carbide tip, cermet, tip, etc. as a cutting edge, which exhibits high performance in cutting heat-resistant and steel materials, to cut reinforced concrete 2. In order to cut, high-pressure water 3 is jetted through the body plate (not shown) of the circular saw blade 1 during rotary cutting from, for example, very close to the cutting action point 5 of the carbide tip cutting edge 4, and the impact force is used to cut the carbide. A concrete part of the reinforced concrete 2 that is very close to the cutting action point 5 of the chip cutting edge 4 is excavated and rocked to generate a crack 6, and the carbide chip cutting edge 4 is cooled with water accumulated in the chip space 7 of the circular saw blade l. At the same time, the jet traces of the high-pressure water 3 are cut by the carbide tip cutting edge 4, and the chips 9 and excavated chips 10 from the reinforcing bar 8 are stored in the chip space 7 of the circular saw blade 1 and removed to the outside. The cutting progresses by scraping.

Incidentally, assuming that the impact force generated by the high-pressure water jet 3 momentarily stops the movement of the cylindrical liquid and does not flow sideways, then P=reV P: impact pressure (dyne 7cm) r: pressure of the liquid Specific weight (, V/d) C: Speed of sound in liquid (cm/5ee) V: Velocity of jet (C bottom/5ee).

On the other hand, the velocity of the jet stream, Bernoulli's formula% formula%) ρ: Liquid density (Kp・ BeO2, lαA) It is.

Now, assuming that the pressure of high-pressure water is P=1000 and 517 m, the speed of the jet stream will be 443 m/see. Assuming that the impact force due to the jet flow at this time is 100% efficient, p = 5 ao oK91a & , efficient 30~
Even if it is 50%, P=1000~3000Kg/ol
It will be seen that it is possible to crush the surface layer of concrete. However, P=1000-3000K
Although it is impossible to cut a steel material with a pressure of about g7'crh, the steel material can be cut by the circular saw blade 1 equipped with a cutting edge.

Next, an example of the apparatus used to carry out the present invention will be explained with reference to FIGS. 2 and 3.

The circular saw blade 1 is attached to a holder 11 by bolting a tightening flange 12, and is configured to be rotated by a drive device (not shown) via a main shaft 13 that supports the holder 11 concentrically. The body plate 1a of the circular saw blade 1, the holder 11, and the distribution ring 14 provided around the inside of the holder 11 are equipped with an injection port 15 that opens near the cutting rotation direction side of the carbide tip cutting edge 4. Water channels 16 are provided radially. In the holder 11, a high-pressure water injection distribution shaft 17, which is slidably fitted into the distribution ring 14, is rotatably supported concentrically with the main shaft 13 by four rings 18. An injection range limiting groove 19 located above the 16 rows of the 14 water passages is provided around the periphery, and a water passage 20 that opens into the groove 19 and the uniaxial end face is provided. In order to prevent water from leaking between the high-pressure water injection distribution shaft 17 and the distribution ring 14, gaskets 21 are provided on both sides of the distribution ring 140 via disc springs 22 and shear adapters 23. Further, the high-pressure water injection and distribution shaft 17 is provided with a rotation adjustment mechanism (not shown). Thus, the circular saw blade 1 is rotated via the main shaft 13 with the opening direction of the high-pressure water injection distribution shaft 17 oriented toward the cutting surface, and the high-pressure water injection and distribution shaft 17 is 3 High pressure water injection distribution shaft 1
When the high-pressure water 3 is supplied to the water conduit 20 of No. 7, the high-pressure water 3 is supplied to the water conduit 16 facing this through the injection range limiting groove 19, and is jetted from the injection port 15 toward the cut surface. .

Therefore, according to this device, the present invention can be carried out reliably.

Note that when the object to be cut is a hard and brittle material such as rock, unreinforced concrete, or mortar, a diamond cutting wheel that is effective for cutting may be used. In this case, supplying a high-pressure water jet from a piped nozzle near the cutting point is effective in reducing the cutting load on the diamond cutting wheel and cooling the cutting wheel. .

(Effects of the Invention) As described above, the present invention achieves the synergistic effect of the circular saw blade and the jet of cutting fluid (retention of the blade edge, sharing of cutting of steel and concrete, scraping of chips, etc.). Enables efficient cutting of concrete. Therefore, it can be effectively used for remodeling and demolition of concrete structures.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, FIGS. 2 and 3 are front sectional views showing an example of a device used to carry out the present invention, and a cross section taken along the line iIl in FIG. 2. It is a diagram. 1.901. ! i-blade, 1a"・J'A"J plate, 2・
・Reinforced concrete, 3. High pressure water (high pressure water jet), 4. Carbide tip cutting edge, 5. Cutting action point, 6
・°Crack) 7. Chip space, 8. Reinforcement bar, 9. Chips, 1
0...Drilling JF3°. Figure 2 “1 Figure 3

Claims (2)

[Claims] (1) A cutting agent is jet-injected very close to the cutting action point of a rotating circular saw blade, and cutting is progressed by cutting the injection trace of the cutting agent with the circular saw blade. How to cut steel-filled concrete. (2) A hard-brittle method characterized by spraying a water jet extremely close to the point of cutting action of a rotating diamond cutting wheel, and progressing the cutting by cutting the jet traces of the water jet with the diamond cutting wheel. How to cut the material.