JPH027912B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a steam heating curing device for precast concrete plates used in construction work.

Conventional technology Precast concrete plates are made by placing embedded hardware, fittings, etc. in a mold frame at a factory and loading pre-assembled reinforcing bars, then pouring concrete, treating the surface of the concrete, covering it with a curing sheet, and then steaming it. It is manufactured through a process of curing and demolding.

During this process, steam curing is performed to increase the strength and quality of concrete, shorten the hydration reaction time, and improve productivity. In order to prevent cracks in the concrete caused by hydration and promote a uniform hydration reaction, the heating pattern shown in Figure 3 is required. It is necessary to increase the temperature at a certain rate and then gradually lower the temperature after a certain period of time has elapsed.

Conventionally, as shown in Fig. 4, a steam curing device has been constructed by placing a mold frame 2 for a precast concrete plate on a bed 1 made of a steel plate, and connecting a steam pipe 4 to a heating chamber 3 surrounding the mold frame 2. A device for directly heating a precast concrete plate by blowing out steam, and a mold frame 2 for a precast concrete plate are placed on a steel plate bed 1 as shown in FIG.
Steam pipe 4 having an outlet in the heating chamber 3 below it
The automatic heating system consists of thermostats 5 installed every few beds and a temperature control machine that controls the set temperature using a rotary cam to indirectly heat the precast concrete board. It is known that the solenoid valve 6 is opened and closed by a control device.

Problems to be Solved by the Invention The above-mentioned conventional curing equipment using direct heating has extremely low thermal efficiency because the high-pressure, high-temperature steam coming from the boiler is not used as it is, but is blown into the room to reduce the pressure, and the drain cannot be recovered. ,
In addition, because the floor and walls of the heating chamber are wide, the heat capacity is large, making it difficult to maintain economical heat retention performance.Also, steam leakage cannot be avoided, resulting in a large loss of heat. However, there is a problem in that the temperature of the steam differs, and the high temperature of the steam and the large amount of heat transfer, together with the large disparity in heating temperature, make it impossible to obtain concrete plates of uniform quality. As with direct heating, the device blows steam into the heating chamber to reduce the pressure before use, and because the drain cannot be recovered, the thermal efficiency is extremely low.Also, since the steam is at a high temperature, the amount of heat transfer is large, and the amount of heat transferred per hour is extremely low. 20℃
Expensive automatic control equipment must be used to maintain the rising heating pattern, and even if automatic control equipment is used, it is done by opening and closing a solenoid valve, resulting in a stepped heating pattern and wasting steam. Another problem is that the amount of steam heat transfer must be changed because the load changes depending on the season and temperature changes, which requires the use of expensive automatic control equipment. Ta.

Means for Solving the Problems The means of the present invention for solving the above-mentioned problems are as follows: 1. An adiabatic heating chamber is provided on the lower surface of the mounting frame of the precast concrete plate mold frame, and the water volume is heated at a predetermined rate at the bottom of the chamber. 2. A steam heating curing device for precast concrete plates, which is equipped with a water tank equipped with a flow rate restriction device that reduces the flow rate, and a steam heating pipe is installed in the water tank. A water tank is provided at the bottom of the tank with a flow rate restriction device that reduces the amount of water at a predetermined rate, and a steam heating pipe is installed so that it slopes toward the bottom of the tank after passing horizontally over the water surface. It consists of a steam heating curing device for precast concrete plates.

Effect The operation of this invention is as follows.

Concrete is poured into a precast concrete plate mold frame, placed on a mounting stand, and the solenoid valves for the steam heating pipes away from the water tank, the steam heating pipes in the water tank filled with water, and the solenoid valve for condensed water recovery are installed. When the tank is opened, the water in the tank boils and generates steam, which increases the amount of heat transfer and raises the temperature of the concrete at a rate of approximately 20°C per hour. During this time, the water in the tank evaporates and decreases, but since the condensed water is collected into the tank through the recovery flow rate restriction device, a suitable amount of water can be maintained. Two hours later, when the temperature reaches 60°C, the water in the water tank decreases until it reaches below the steam heating pipe because the inflow of condensed water is restricted by the flow rate restriction device. The water in the water tank is then drained, and the temperature of the concrete is maintained at 60℃ for about 2 hours using radiant heat from the steam heating pipe, and the supply of steam is stopped after the hydration reaction of the concrete is completed. Then finish the steam curing. In this case, it is necessary to adjust the amount of heating according to changes in temperature such as winter and summer, and by tilting the steam heating pipe and raising and lowering the water level, the heat transfer area can be changed and the amount of heat generated can be adjusted. By selecting the size of the restriction hole of the flow restriction device in the condensed water recovery pipe, the inflow amount of condensed water is adjusted so that the heating time is kept constant even if the amount of water changes.

Embodiment An embodiment of the present invention will be described based on the drawings.

In FIG. 1, numeral 10 is a mold frame for a precast concrete plate, which is placed on a mounting stand 12 having a steel plate 11 on the top. A bottom part 15 is formed on the lower surface of the mounting table 12 by covering a heat insulating material 13 with a stainless steel plate 14, and an adiabatic heating chamber 17 with a water tank 16 provided in the center thereof is provided.

In the water tank 16, two steam heating pipes 18, 18 are provided horizontally passing through the upper part of the water tank 16, then turned back and tilted toward the lower part of the water tank 16, and a solenoid valve 19 is provided on the steam inflow side and on the discharge side. The water is circulated through the steam trap 20 to the water tank of the boiler.

Steam heating pipes 21 and 22 are arranged at positions away from the water tank 16 in the adiabatic heating chamber 17, and a pipe 24 for collecting condensed water is connected to a solenoid valve 25 and a flow rate restriction device on the water receiving plate 23 of the stainless steel plate 14. It opens into the water tank 16 through an orifice plate 26, and a pipe 27 opens into a drainage groove (not shown) at the bottom of the water tank 16, and the orifice plate 26 can be replaced with one of various limiting hole diameters. It is designed to be installed on the flange. The inflow amount of condensed water through the orifice plate 26 is designed so that the water in the water tank 16 decreases by evaporation and reaches the lower surface of the steam heating pipe 18 after the temperature of the adiabatic heating chamber 17 reaches 60°C. 18 is designed so that when the electromagnetic valve 19 is opened, the water in the water tank 16 boils and generates an amount of heat that increases the temperature of the precast concrete plate by 20°C per hour.

When steam is passed through the steam heating pipe 18 in the water tank 16,
It is difficult for the steam evaporated from the water tank 16 to reach the part of the adiabatic heating chamber 17 away from the water tank 16, so the temperature decreases, but the heating temperature is now ensured by the radiant heat of the steam heating pipes 21 and 22. There is.

Effects of the Invention The first invention generates steam by disposing a steam heating pipe in the water tank, so there is no uneconomical effect of blowing steam directly from the steam heating pipe and reducing the pressure before use, and there is no drain. There is no reduction in thermal efficiency due to the inability to recover heat, and since the underside of the mounting frame for the precast concrete plate mold is made into an insulated heating chamber, heat loss due to steam leakage from a large room unlike conventional direct heating is avoided. It can be avoided. In particular, the present invention makes it possible to reduce the amount of water in the water tank at various speeds by selecting a flow rate limiting device, and to maintain the heating time of the steam heating pipe in the water tank for a predetermined time. By setting the area of the water tank appropriately, the heating temperature can be set to a temperature that maintains the heating pattern, so the equipment is economical without the need for complicated and expensive automatic control equipment as in the past. Moreover, since the heating pattern does not become step-like unlike the conventional temperature control which is performed by opening and closing a solenoid valve using an automatic control device, there is an effect that no excess steam is wasted.

In addition to the effects of the first invention, the second invention has the steam heating pipe installed at an angle in the water tank, so that the water level in the water tank can be changed according to changes in the season and temperature to generate steam. Since the amount of heat generated can be adjusted by changing the area where the heat is generated, and thereby the heating temperature can be adjusted, there is no need to provide an expensive automatic control device as in the past.

[Brief explanation of drawings]

1 and 2 show one embodiment of the present invention, in which FIG. 1 is a longitudinal sectional front view, FIG. 2 is an enlarged side sectional view taken along the line of FIG. 1, and FIG. Graphs showing heating patterns, and FIGS. 4 and 5 are longitudinal sectional front views showing conventional examples, respectively. 10... Precast concrete board mold frame, 12... Mounting stand, 15... Bottom, 16... Water tank, 17... Insulated heating chamber, 18... Steam heating pipe,
21...Steam heating tube, 22...Steam heating tube, 26
...Flow restriction device.

Claims (1)

[Scope of Claims] 1. An adiabatic heating chamber 17 is provided on the lower surface of the mounting stand 12 of the precast concrete plate mold frame 10, and a water tank 16 is provided at the bottom 15 of the chamber 17 with a flow rate restriction device 26 that reduces the amount of water at a predetermined speed. and the water tank 16
A steam heating curing device for a precast concrete plate with a steam heating pipe 18 installed inside. 2. An adiabatic heating chamber 17 is provided on the lower surface of the mounting frame 12 of the precast concrete plate mold frame 10, and a water tank 16 is provided at the bottom 15 of the chamber 17 and has a flow rate restriction device 26 that reduces the amount of water at a predetermined speed. A steam heating curing device for a precast concrete plate in which a steam heating pipe 18 is arranged so as to be inclined toward the lower part of a water tank 16 after passing horizontally through the water tank 16. 3. The steam heating curing device for a precast concrete plate according to claim 1 or 2, wherein steam heating pipes 21 and 22 are arranged in a position away from the water tank 16 in the adiabatic heating chamber 17.