JPH0562043B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <<Industrial Application Field>> The present invention relates to a track mixer, and particularly to one having a function of cooling concrete within a mixer drum.

<<Prior Art>> Concrete manufactured during hot weather has a high mixing temperature, which increases the unit amount of water required to obtain the same consistency, and increases the unit amount of cement required to achieve the same water-cement ratio. In addition, the drop in slump during transportation becomes greater, and the unit amount of water and cement must be further increased. This is not only uneconomical, but also increases the temperature rise due to the heat generated by the cement, increases drying shrinkage, and increases the possibility of defects such as cracks occurring. Furthermore, it hardens quickly, reducing the time allowed for joints and making construction difficult.

Furthermore, in mass concrete, concrete is a poor conductor of heat, and as it hardens and heats up, the internal temperature rises, increasing the temperature difference between the inside and outside surfaces, and surface cracks are likely to occur.
Also, if the concrete is restrained from the outside,
The shrinkage caused by the temperature drop after curing is also constrained, creating large tensile stresses. For these reasons, it is necessary to take measures to keep the mixing temperature to a certain degree low for hot concrete and mass concrete.

Conventionally, in order to keep the mixing temperature of concrete low, methods such as cooling cement, aggregate, water, and other materials, and using crushed ice in the mixing water were used.

<<Problems to be Solved by the Invention>> Methods for cooling materials such as cement, aggregate, and water have low cooling effects despite the large scale of cooling equipment, and quality control is also difficult. The method of using broken ice also requires large-scale ice-making equipment, and it is difficult to appropriately control the temperature and moisture content of the concrete. Conventionally, the above-described cooling method requires large-scale equipment, so it has been implemented in concrete plants. Therefore,
When transporting concrete using a truck mixer to a concrete placement site that is far from the plant, the temperature of the concrete will rise at the placement site even if it is cooled at the plant stage.

This invention was made in view of the above-mentioned background, and its purpose is to use a very simple liquefied gas as a cooling source to cool concrete while it is being transported to the pouring site using a truck mixer or upon arrival at the site. To provide a track mixer equipped with a cooling function capable of effectively cooling concrete in a drum in a short time.

<Means for Solving the Problems> In the present invention, a drum located on the axis of rotation of the drum of a track mixer (in the case of a drum type) or on the axis of rotation of the mixing blade in the drum (in the case of a high-low type) A nozzle device was provided inside the center of the bottom, liquefied gas was supplied from the outside to this nozzle device, and the liquefied gas was injected onto the concrete in the drum.

<<Effect>> When liquefied gas such as liquid nitrogen evaporates, an extremely large cooling effect can be obtained. This cooling effect allows the concrete being mixed by the track mixer to be rapidly cooled down to the desired low temperature. When the liquefied gas evaporates, it completely escapes from the concrete and has no effect on the quality of the concrete.

<<Example>> The appearance of the track mixer according to the present invention is shown in the third example.
As shown in the figure.

In the figure, 10 is the chassis of the truck, 1
2 is a drum mounted on the chassis 10. The center line P of the drum 12 is tilted at an appropriate angle with the rear facing up, and the drum 12 is driven to rotate around this center line P.
That is, the shaft support 14 is located at the center of the bottom 12a of the drum 12, and this portion is rotatably attached to the chassis 10. Further, the rear end side of the drum 12 is open, and a hopper 16 and a chute are provided correspondingly thereto. In addition, 18 is a gear fixed to the bottom 12a of the drum 12 concentrically with the center line P, 20 is a roller chain that extends over the gear 18, and 22 is a gear with a speed reducer that rotationally drives the drum 12 via the roller chain 20. This is a hydraulic motor.

A nozzle device 24 shown in FIGS. 1 and 2 is attached through the above-mentioned shaft support 14 portion. As shown in FIG. 1, in the shaft support 14, a hollow shaft 14a is fixedly installed concentrically with the center line P of the drum bottom 12a.
a is rotatably supported on the truck chassis 10 side via a bearing 14b.

The nozzle device 24 is attached so as to penetrate the hollow shaft 14a and protrude inside the drum bottom 12a. The nozzle device 24 includes a pipe section 26 fitted into the hollow shaft 14a, a nozzle unit 28 attached to the tip of the pipe section 26, and a rotary pipe joint 3 attached to the outer end of the pipe section 26.
Consists of 0. A flexible hose 32 is connected to the rotary ring joint 30. This hose 3
2 is connected to a storage tank for liquefied gas (for example, liquid nitrogen), which is not shown. The liquefied gas storage tank may be mounted on the truck chassis 10, or
It may also be installed at the concrete pouring site.

Details of the nozzle unit 28 are shown in FIG. The unit 28 is pipe-shaped with a closed end and communicates with the pipe portion 26. This unit 28 has a large number of nozzle holes 28 that penetrate inside and outside.
a is formed. A check valve 28b is attached to the outside of the nozzle hole 28a. This check valve 28
b allows injection of liquefied gas from the inside to the outside of the nozzle hole 28a, and conversely prevents mortar etc. from entering the nozzle unit 28 from inside the drum 12. Further, a heat transfer heater 28c is attached to the inner side of the nozzle hole 28a, and when the heater 28c is energized, the nozzle hole 28a is heated. Heat transfer heater 28c has lead wire 28d
connected to the outside.

In the above configuration, while the truck mixer is transporting concrete to the concrete placement site or after the concrete has arrived, the hose 3 is
Supply liquefied gas to 2. Then, the liquefied gas flows from the nozzle hole 28a of the nozzle device 24 to the drum 1.
It squirts inside 2. The nozzle unit 28 is attached to the drum 1
Since the drum 12 is located on the center line P of the drum 12, the liquefied gas ejected from here evenly spreads inside the drum 12. The concrete in the drum 12 is rapidly cooled by the latent heat and sensible heat of this liquefied gas.
The rotation of step 2 cools the entire concrete evenly. The vaporized gas dissipates into the atmosphere from the portion of the hopper 16 on the open side of the drum 12.

At the same time as the liquefied gas is injected, the electric heater 28c is energized to heat the nozzle hole 28a. This is to prevent the area around the nozzle hole 28a from freezing due to rapid cooling caused by the liquefied gas.

In the above embodiment, a truck mixer is used in which the drum 12 rotates to mix concrete, but the present invention is not limited to this.
The present invention can also be applied to a track mixer in which the drum is fixed and the kneading blades inside the drum rotate. In this case, if the nozzle device 24 is located on the rotational axis of the mixing blade and provided at the center of the bottom of the drum, the nozzle device 24 and the mixing blade will not interfere with each other, and the liquefied gas spouted will be directed into the drum. It can be spread evenly.

<<Effects of the Invention>> As explained in detail above, according to the track mixer equipped with a cooling function according to the present invention, it is not necessary to equip a concrete plant with large-scale cooling equipment as in the past, and the track mixer can handle concrete. The concrete can be cooled quickly during transportation or after arrival, and can be successfully applied to hot concrete and mass concrete. Moreover, the equipment and work required for this purpose are extremely simple.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the vicinity of a nozzle device of a track mixer according to an embodiment of the present invention, and FIG. 2 is a partially enlarged sectional view of the nozzle unit in FIG. 1.
FIG. 3 is a perspective view showing an example of the appearance of a track mixer according to the present invention. 10... Truck chassis, 12... Drum,
14... Axial support, 24... Nozzle device, 26...
Pipe section, 28... Nozzle unit, 28a...
Nozzle hole, 28b...Check valve, 28c...Electric heater, 28d...Lead wire, 30...Rotary ring joint, 32...Hose.

Claims (1)

[Claims] 1. In a truck mixer in which a mixer drum is mounted on a truck chassis, a nozzle device is provided inside the center of the bottom of the drum located on the rotational axis of the drum or on the rotational axis of a mixing blade in the drum, A track mixer equipped with a cooling function configured to supply liquefied gas to the nozzle device from the outside and inject the liquefied gas onto the concrete in the drum to cool the concrete.