JPH0364286B2 - - Google Patents

Description

Detailed Description of the Invention <Industrial Field of Application> The present invention involves putting fresh concrete into a predetermined formwork, such as a tapered seamless pipe, one-split pipe, two-split pipe type, etc., and centrifuging it. The present invention relates to a method and apparatus for demolding and heating a concrete pipe, in which after a molded product is heated and cured, the mold is expanded and relaxed by heating to facilitate extrusion or pulling out of the concrete pipe with a socket.

<Prior art> Conventional methods for heating the formwork after concrete curing and before demolding include using gas burners, steam, heated water, etc., but these methods have low initial cost, running cost, workability, etc. of the heating equipment. Furthermore, it is already known that the heating method using heated water is the best method when considering the yield of the product.

External pressure pipes as an example of concrete pipes are JIS
As stipulated in The two-way tie is 13 to 24.

For this reason, in type 2 concrete pipes, expandable concrete containing 12 to 13% of expanding material is used, and due to its expandability, in type 2 concrete pipes, the adhesion between the outer surface of the concrete pipe and the inner surface of the formwork is reduced. , are much larger than Type 1 concrete pipes, making it difficult to demold Type 2 concrete pipes.

A conventional heating method for demolding a concrete pipe is disclosed in, for example, Japanese Patent Laid-Open No. 62-294509.

This publication describes a configuration in which the pipe of the heating device that spouts hot water at 40°C is moved, and an alternative configuration in which the formwork is moved in its axial direction without moving the heating device; , a configuration in which a large number of tubes are arranged around the formwork in its axial direction, and a heating medium is sequentially jetted from the tubes, and further, in addition to the aforementioned movement of the tubes of the heating device, the formwork is A configuration in which the tube is rotated around an axis or in place of rotation of the formwork, and further,
A configuration is described in which the temperature drop at the heating point after heating is reduced by covering the periphery of the tube and the formwork.

In other words, this publication describes a configuration in which 40°C hot water (heated water) is sequentially sprayed and heated over the outer circumferential portion of the formwork, excluding the spigot and socket portions, and the formwork is demolded. .

<Problems to be Solved by the Invention> However, in the configuration of this publication, the water jet holes are close to the outer periphery of the formwork, so even though the spigot and socket parts may be heated from the sides,
Since the heating water is not heated directly above and the heating water temperature is low, even if heating ends just before the socket, the specified temperature difference (15
℃), and a predetermined temperature difference cannot be maintained until the end of the entire heating, and in particular, type 2 concrete pipes cannot be demolded smoothly.

This is because the concrete pipe and formwork have a slightly higher coefficient of thermal expansion, and the formwork has a higher thermal conductivity. This is because if the heating conditions are poor and heating is continued for more than about 120 seconds, the concrete pipe will expand significantly and the concrete pipe will be crimped again to the formwork that was once demolded.

<Purpose> The present invention starts by spraying heated water from one end of the formwork, including the spigot part, to ensure relaxation of this part, and then gradually sprays heated water to the other end, including the socket part of the formwork. The purpose is to increase the number of spraying locations and ultimately to heat the entire outer circumference from one end to the other with heated water to enable smooth demolding of not only Class 1 concrete external pressure pipes but also Class 2 concrete external pressure pipes. It is said that

<Means for Solving the Problems> As shown in FIGS. 1, 2, and 3, the means for solving the problems according to the present invention is a mold in which fresh concrete is poured into an iron mold 6, centrifugally formed, and the fresh concrete pipes 7 are heated and cured. The frame 6 is placed on the formwork support stand 9, and the outer holding part 8 of the one end (spigot side) part A of the formwork 6 is grasped by the gripping device 17 of the demolding pressure device Y, and the formwork 6 is One end of the concrete pipe 7 with a socket is pressed onto the plate 16.
Apply extrusion pressure in the axial direction of the other end through the first shower 5-1, and spray heated water of 70 to 100°C evenly for 15 to 30 seconds over the entire circumference of one end part A of the mold. First, only one end portion A is relaxed by heating,
After a delay from the start of watering from the first shower, the second shower 5-2 sprays heated water of the same temperature as above over the entire circumference of the intermediate portion C that is continuous with one end portion A of the formwork, and evenly heats this intermediate portion. Part C is relaxed and the first
The shower continues to sprinkle water, and after a delay from the start of watering from the second shower, a third shower 5-3 is applied to the entire circumference of the other end large diameter (socket side) portion B that is continuous with the middle portion C of the formwork 6. The other end B is relaxed by spraying warm heated water and heated evenly, and the first and second showers continue to spray water, and when the concrete pipe 7 starts to be removed from the formwork 6, the heated water is sprayed. Stop all spraying.

<Function> In the above, start spraying heated water at 70 to 100°C from one end of the formwork including the spigot part to ensure relaxation of this part, and then step by step to the end including the socket part of the formwork. By increasing the number of locations where heated water is sprayed and ultimately heating the entire circumference from one end to the other with heated water, it is possible to demold not only Class 1 concrete external pressure pipes but also Class 2 concrete external pressure pipes in about 90 seconds. It becomes possible.

<Example> An example of the present invention will be described below based on FIGS. 1, 2, and 3. Figure 1 is a side view of a device that performs a heating method for demolding concrete pipes, Figure 2 is a cross-sectional view of the main part taken along the - line in Figure 1, and Figure 3 is a diagram showing the relationship between heated water spraying state and time. It is.

In the figure, reference numeral 1 denotes an electric heater or a burner heating machine for heating the water in the heated water tank 2 after the above-mentioned heating. The heated water is divided into three parts by a pipe, and is supplied to motor valves (solenoid valves) 3-1, 3-2, and 3-3, respectively, and is further supplied to motor valves 3-1, 3-2, and 3-3.
3-2 and 3-3 are adjustment valves 4-1 and 4, respectively.
-2, 4-3, and regulating valve 4.
-1, 4-2, and 4-3 are the first shower 5-1, the second shower 5-2, and the third shower 5-, respectively.
It is connected to 3. And each shower has a second
As shown in the diagram, it consists of seven pipes placed outside the formwork.

In addition, the flow rate adjustment is carried out in advance by adjusting valves 4-1 and 4-4.
-2, 4-3. Therefore, the heated water is configured to flow from the heated water tank 2 through the pressurizing pump 11, through the motor valve, and through the regulating valve to the shower. The first shower 5-1 sprays heated water onto the spigot side portion A of one end of the iron formwork 6, and the second shower 5-2 sprays heated water onto the intermediate portion C continuous to the spigot side portion A. The third shower 5-3 is for spraying heated water onto the socket side portion B at the other end continuous with the intermediate portion C. Set the time switch etc. so that the heated water flows sequentially from A to C to B. Of course, the heated water is sprayed simultaneously using several shower pipes from the circumferential direction of the formwork 6 as shown in Fig. 2, and the number of shower pipes used depends on the size of the concrete pipe 7 of the product (2~ 2.5m), Type 1, Type 2, etc., depending on the temperature, etc., may be adopted as appropriate within the above numerical range.

Then, there is a formwork support stand 9 on which the formwork 6 in which fresh concrete is put into a steel formwork 6, centrifugally formed, and the ready-mixed concrete pipe 7 is heated and cured is placed thereon, and a spigot side portion at one end of the formwork 6. A's outer holding part 8
and a pressing cylinder 15 that applies extrusion pressure to one end of the concrete pipe 7 with a socket in the formwork 6 in the axial direction of the other end via the pressing plate 16.
A demolding pressurizing device Y is provided.

In addition, the first shower 5-1 sprays heated water of 70 to 100°C around the entire circumference of the spigot side part A of the formwork and heats it evenly for 15 to 30 seconds to spray only the spigot side part A. First, make sure to relax.

The second shower 5-2 sprays heated water of the same temperature as the above over the entire circumference of the intermediate portion C that is continuous with the spigot side portion A of the formwork 15 to 30 seconds after the start of the first heating step. Heat this middle part C evenly.
relax. The third shower 5-3 heats the entire circumference of the large-diameter socket side portion B that is continuous with the middle portion C of the formwork 6 at the same temperature 5 to 30 seconds after the start of the second heating step. Sprinkle water and heat evenly to loosen this socket side part B.

In addition, the reference numeral 10 indicates heated water, 12 indicates a return pump, and the heated water 10 after spraying is transferred to the heated water tank 2.
It serves the purpose of returning it to The demolding pressurizing device Y is a trolley 1
4, it can be moved on the rails with wheels, and is fixed to the rails during operation. 1
3 is a scattering prevention cover, and the demolded concrete pipe 7 can be transferred by an extrusion cylinder 15 and a feed roller 20 at its front end to a product cart 19 movable on a rail on a product pedestal 18. . The product pedestal 18 is also movable in the vertical direction. The concrete pipe 7 after demolding is placed on the product cart 19 via the extrusion cylinder 15.

Next, to explain the operation, fresh concrete is poured into a steel formwork 6, centrifugally formed, and the fresh concrete pipe 7 is heated and cured.
The outer holding part 8 of the spigot side part A of the formwork 6 is gripped by the gripping device 17 of the demolding pressure device Y, and one end of the concrete pipe 7 with socket of the formwork 6 is held by the push plate 16. Extrusion pressure is applied in the axial direction of the other end using the press cylinder 15 (extrusion process).

Next, heated water of 70 to 100°C is sprayed by the first shower 5-1 around the entire circumference of the spigot side part A of the formwork, and heated evenly for 15 to 30 seconds, so that only the spigot side part A is heated. First, make sure to relax (first
heating process).

Next, 15 to 30 seconds after the start of the first heating step, heated water of the same temperature as above is sprayed by a second shower 5-2 onto the front circumference of the intermediate portion C that is continuous with the spigot side portion A of the formwork. The intermediate portion C is heated evenly to relax the intermediate portion C, and the first shower continues to spray water (second heating step).

5 to 30 seconds after the start of the second heating process, heated water of the same temperature as above is applied from the third shower 5-3 to the front circumference of the large diameter socket side part B that is continuous with the middle part C of the formwork 6. The socket side portion B is relaxed by being sprayed and heated evenly, and the first and second showers continue to spray water (third heating step).

The concrete pipe 7 is separated from the formwork 6 in about 90 seconds from the start of watering from the first shower.
A predetermined temperature difference (for example, 15°C) is created in between, and when demolding begins, all spraying of heated water is stopped (demolding process).

Note that when the concrete pipe 7 and the formwork 6 are heated, thermal expansion occurs in the radial direction and the thrust direction. Thermal expansion in the radial direction always works in the direction of relaxation, so there is no problem, but if the thermal expansion in the thrust direction is not sufficiently relaxed in the radial direction, the steel formwork 6 will conduct heat better than the concrete pipe 7. Not only that, but also the heated water is applied directly to the formwork 6, resulting in large thermal expansion. Therefore, tensile stress is generated in the concrete pipe 7 in the thrust direction.
For this reason, when heated rapidly, the temperature difference between the concrete pipe 7 and the formwork 6 increases, so naturally the expansion difference also increases. As a result, the tensile stress also increases and cracks occur in the concrete pipe 7.

In order to thermally expand the concrete pipe 7 with a temperature difference that does not cause cracks and to make demolding easier, it is necessary to gradually heat the pipe and to maintain sufficient temperature control.

For example, in FIG. 1, heated water is applied to the spigot side part A, the socket side part B, and the middle part C of the formwork 6 at the same time, or the spigot side part A,
A case will be described in which after the socket side portion B is heated with heated water, the intermediate portion C is heated. In particular, in the case of the concrete pipe 7 with a socket, if heated water is applied to the former spigot side part A, socket side part B, and middle part C at the same time, ) to one end of the spigot side part A was completely relaxed in the radial direction of the formwork 6, and after heating the latter spigot side part A and socket side part B with heated water, the middle part C was heated. In this case, since the intermediate part loosens after the spigot side part A and the socket side part B, a crack naturally occurs between part a of the socket side part B and the middle part C (this part C is in a hoop state). It becomes easier.

However, in the method of demolding and heating a concrete pipe according to the present invention, heated water of 70 to 100°C is sprayed around the entire circumference of one end portion A of the formwork by the first shower 5-1.
First, only one end part A is relaxed by heating evenly for 30 seconds, then the middle part C and the other end large diameter part B are sequentially relaxed by the second and third showers, and the first,
The second and third showers continue to spray water, and when the concrete pipe 7 starts to be removed from the formwork 6, all the spraying of heated water is stopped. Therefore, according to the present invention, no tensile stress is generated in the thrust direction in the concrete pipe 7, which is the product, so a product with no cracks and a high yield can be obtained, and the initial cost and running cost can be greatly reduced. It will be planned. This method of demolding and heating a concrete pipe is particularly suitable for the concrete pipe 7 with the socket side portion B, and makes demolding extremely easy and can shorten the time required.

Moreover, since the concrete pipe 7 is heated by applying extrusion pressure with an extrusion cylinder, the product always generates compression pressure due to the extrusion pressure in the thrust direction.
Even if a small amount of tensile stress is generated in the product due to thermal expansion during heating, the compressive force and tensile force cancel each other out. Therefore, the internal stress of the product approaches the compression side or becomes compressive stress, so that cracks are almost eliminated.

From the above, the concrete pipe 7 product with a good yield can be obtained, and the initial cost and running cost can be greatly reduced.

Next, experimental examples of types 1 and 2 of JIS external pressure pipes will be described.

[1 type of external pressure pipe] Heating water temperature: 80°C Spraying time of heated water to the spigot side part A of the formwork 6: 15 seconds Temperature change in the spigot side part A of the formwork 6 30°C at the start of heating water → 15 seconds later 45℃→90 seconds later (at the end of heated water spraying) 65℃ Temperature change at one end 7a of the concrete pipe 7 30℃ at the start of heated water→90 seconds later (at the end of heated water spraying) 45℃ [Two types of external pressure pipes] ] Heating water temperature: 88℃ Spraying time of heated water to spigot side part A of formwork 6: 30 seconds Temperature change in spigot side part A of formwork 6 15℃ at the start of heating water → 15 seconds later 55℃ → 90 seconds later (At the end of heated water spraying) 64°C Temperature change at the starting end 7a of the concrete pipe 7 15°C at the start of heated water → 45°C after 90 seconds (at the end of heated water spraying) <Effects of the invention> As is clear from the above explanation , the present invention provides a method of applying 70 mm to the entire circumference of one end of the iron formwork by means of a first shower.
Spray heated water at ~100℃ and heat evenly for 15 to 30 seconds to ensure that only one end is relaxed first, then use the second and third showers to loosen the middle part and the large diameter part of the other end in sequence. In addition, the first, second, and third showers continue to spray water, and when the concrete pipe starts to be removed from the formwork, all spraying of heated water is stopped.

Therefore, according to the present invention, approximately
Heating for more than 120 seconds will cause the concrete pipe to expand significantly, and the concrete pipe will not be crimped again to the formwork that was once demolded, and it will take about 90 seconds to create a predetermined temperature difference between the two and demold. It has an excellent effect of enabling smooth demolding of not only type 1 concrete external pressure pipes but also type 2 concrete external pressure pipes.

[Brief explanation of drawings]

Fig. 1 is a side view of an apparatus that implements the concrete pipe demolding heating method of the present invention, and Fig.
FIG. 3 is a cross-sectional view of the main part taken along the - line in the figure, and is also a diagram showing the relationship between the heated water dispersion state and time. 5-1: first showerer, 5-2: second showerer, 5-3: third showerer, 6: formwork, 7: concrete pipe, 8: outer holding part, 9: formwork support stand,
16: Push plate, 17: Gripping device, A: Spigot side part, B: Socket side part, C: Intermediate part, Y:
Demolding pressure device.

Claims (1)

[Claims] 1 Place fresh concrete into a steel formwork, centrifugally form it, heat and cure the fresh concrete pipe, and place the formwork on a formwork support stand, and pressurize the outer holding part of one end of the formwork to release the form. Grasp it with the device's gripping device,
Extrusion pressure is applied to one end of the concrete pipe in the formwork in the axial direction of the other end through a push plate, and heated water of 70 to 100°C is sprayed by a first shower over the entire circumference of one end of the formwork. First, only one end part is relaxed by heating evenly for 15 to 30 seconds, and after the first shower starts watering, the entire circumference of the middle part continuous to one end part of the formwork is heated with a second shower at the same temperature as above. Spray heated water to evenly heat and relax this middle part, and continue to water the first shower,
After the start of shower watering, heated water of the same temperature as above is sprayed from a third shower over the entire circumference of the large diameter part of the other end that is continuous with the middle part of the formwork to uniformly heat it and loosen this other end part. A method for demolding and heating a concrete pipe, characterized in that the first and second showers continue to sprinkle water, and when the concrete pipe starts to be demolded from the formwork, all spraying of heated water is stopped.