JPH0313044B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing knotted concrete piles, which are mainly used as friction piles as foundation piles for structures, etc., and a formwork for manufacturing them.

Conventionally, in the manufacture of concrete piles known as foundation piles, a rotating centrifugal system is used, in which a half-cylindrical forming form, a driving shaft and a driven shaft are arranged side by side, and rollers are arranged on each of the shafts. Using a device, the formwork is placed on the rollers of a rotary centrifugal device, and the formwork is rotated by the rotation action of the rotary centrifugal device, generating centrifugal force on the concrete material filled in the formwork. This method forms a concrete pile that is integrated with a core material such as a reinforcing bar cage that has been loaded in advance.

However, if the concrete pile to be manufactured is a so-called knotted pile that has knots at the required intervals, it is necessary to provide knot forming parts in the formwork itself at the required intervals. If a molded joint is provided that bulges outward, the shape of the mold in the axial direction becomes irregular, the structure becomes complicated, the axial weight balance is not constant, and the rotational power from the roller on the drive shaft becomes Even if the receiving wheels are arranged in a well-balanced manner at the required intervals in the axial direction of the formwork, depending on their position, the joints forming the bulging shape may occur during centrifugal forming using the rotary centrifugal device. Due to the presence of the molded parts, the balance during rotation tends to collapse, which causes problems such as material separation and weakening of the pile body. In other words, when a passive wheel is installed between the joints, when it receives rotational power,
A large amount of concrete gathers inside the joint molded part whose diameter is expanded outward, and the weight of this part becomes heavier than that of the body. Therefore, the centrifugal force due to rotational action increases at this joint part, and as a result, the rotation The balance becomes unstable and swings are likely to occur. In addition, the forming formwork of the above shape is time-consuming and costly to manufacture, and compressive stress when tensioning the Pc steel material is concentrated at the bent part of the joint forming part that bulges when manufacturing Pc piles. This has the disadvantage that buckling is likely to occur, and reinforcing this will impair balance.

In view of the above, the present invention incorporates a thin or lightweight axially deformed inner formwork for forming joints and a body inside a half-split cylindrical formwork formed from a relatively thick steel plate. By using a special formwork,
By improving the axial weight balance and considering the position of the supporting part of this formwork, the formwork can be supported in an even better balance, allowing for good rotary centrifugal molding without runout, resulting in high quality. This invention was made in an attempt to manufacture a knotted concrete pile, and the present invention aims to provide a manufacturing method thereof and a manufacturing form suitable for carrying out the method.

That is, the present invention provides an inner formwork which has a corresponding half circle on the inside of both half molds of a half-split cylindrical mold that can be opened and closed, and which constitutes a joint molding part and a body molding part. The half bodies are assembled and fixed in a formwork in which the positions of the cut surfaces correspond to the half molds and the joint molded portions are brought into contact with the inner surface of the half molds, and the formwork is fixed to the cylindrical mold. The manufacturing method is characterized by a manufacturing method in which rotary centrifugal molding is carried out by supporting at a position corresponding to the knot molding portion on the outside of the shaped mold. Furthermore, the formwork for manufacturing knotted concrete and piles used in the above is characterized in that a passive wheel receiving rotational power is arranged at a position corresponding to the joint forming part on the outside of the half-split cylindrical formwork. do.

Next, embodiments of the present invention will be described with reference to the drawings together with the apparatus used.

In the figure, 1', 1' are a pair of half molds with a semicircular cross section, which are obtained by dividing a relatively thick steel cylinder into two equal parts in the longitudinal direction. A cylindrical formwork 1 that can be opened and closed in sections is constructed. That is, engaging flanges 2, 2 are extended on the outer sides of the joint surfaces of the half molds 1', 1', respectively, and are provided so that they can be fastened at required locations with fasteners 3, such as bolts and nuts. .

Reference numeral 4 denotes a relatively thin inner formwork that constitutes a joint forming part 4a and a body forming part 4b at required intervals in the longitudinal direction. Fit the half molds 1', 1' so that the positions of the split surfaces correspond to the half molds, and the joint molded portions 4a are brought into contact with the inner surfaces of the half molds 1', 1'. Flanges 5, 5, which serve as mating surfaces provided on the outside of the joint ends of the bodies 4', 4', are welded to the inside of the joint ends of the half molds 1', 1', or by using countersunk screws 6 as shown in the figure. They are fixed by fastening or other means so that they can rotate together.

Note that the inner mold frame 4 is not limited to a plate-shaped one as in the above embodiment;
It is possible to form a thick block of lightweight synthetic resin or the like so that the entire outer periphery is inscribed in the cylindrical formwork 1. In this case, the inner formwork 4 can be formed into a cylindrical form using its thick wall. It can also be fastened to the formwork 1 with bolts 7.

In any case, as for the inner formwork 4 consisting of the half bodies 4', 4', the joint molded part 4a and the trunk molded part 4b are alternately formed over the entire length as shown in FIG. 1 or 3. There are cases in which it is formed continuously, and cases in which it is formed separately into a plurality of bodies for each body part molded part 4b at the outer circumferential surface part 14a of each joint part molded part 4a.

In addition, when the inner formwork 4 is formed as a thin plate having approximately the same wall thickness as a whole, circumferential ribs 8 are provided on the outer periphery of the body molded portion 4b at required locations in the longitudinal direction, and shafts are provided at required intervals in the circumferential direction. It is desirable to provide the ribs 9 in the direction so as to be inscribed in the cylindrical formwork 1, so that the inner formwork 4 can be reinforced and thinned.

As described above, the formwork used in the present invention uses a thick-walled steel cylindrical body with a uniform cross section as the outer formwork, and uses a thin or lightweight inner formwork with an irregular shape in the axial direction. This aims to improve the directional weight balance, and in order to improve the balance when the formwork rotates, passive wheels that transmit rotation to the formwork are installed as follows.

In the figure, reference numeral 10 denotes a passive wheel that receives rotational power;
It has a half-shaped shape corresponding to 1', and becomes a ring-shaped passive ring when both half molds 1', 1' are closed. The axial position of the driven wheel 10 is set at a position corresponding to the joint molded portion 4a as shown in the figure to improve balance.

That is, although the formwork of the present invention has a relatively good axial weight balance as described above, during centrifugal forming of piles, the irregularly shaped inner formwork portions, that is, the joint forming portions 4a, are filled with a large amount of fresh concrete c. The centrifugal force in this part may be greater than in other parts, and the weight balance during rotation may be disrupted. for that,
The driven wheel 10 is arranged as described above.

As described above, the present invention uses a formwork A in which the inner formwork 4 constituting the joint forming part 4a and the body forming part 4b is incorporated inside the cylindrical formwork 1, and this formwork A is rotated. A knotted concrete pile is centrifugally formed by placing it on a centrifugal device so as to support it at a position corresponding to the knot forming portion 4a. During this forming, the cylindrical formwork 1 and the inner formwork 4 incorporated therein are divided into two parts, a core material such as a reinforcing bar cage is loaded inside the cylindrical formwork 1, and ready-mixed concrete is filled, and then the cylindrical formwork is formed. The half molds 1', 1' of the frame 1 and the half bodies 4', 4' of the inner mold 4 incorporated therein are closed and fastened, and at the same time, circular lids 11, 1 are attached to both ends of the mold.
Insert 1. And formwork A in this state,
As shown in FIGS. 4 and 5, the driven wheel 10 is placed on a rotating centrifugal device so as to be supported by a driving roller and a driven roller, and rotated by the roller to formwork A via the driven wheel 10. The knotted concrete pile P is manufactured by applying the above-mentioned properties, performing rotary centrifugal molding using a known method, and further performing steam curing, hardening, demolding, etc. after molding in the same manner as in the past. After manufacturing, by releasing the fastening of the halves 1', 1' of the formwork 1 and dividing it, the inner formwork 4 is simultaneously opened and the concrete piles can be taken out without difficulty.

The present invention forms or manufactures a knotted concrete pile as described above, and the formwork A used for this is a simple half-cylindrical formwork 1 with the same diameter over the entire length, and a corresponding one. Since it has a half-circle shape and is made of a combination of the joint molded part 4a and the inner mold frame 4 that constitutes the body molded part 4b, the strength is improved during centrifugal molding, transportation, and tensioning of the PC steel material. The outer cylindrical form 1 may be made of thick steel to make it strong, and the inner form 4 may be made thin to the extent that it does not interfere with molding, or may be made of synthetic resin, which is lighter than metal. This is possible, and this makes it possible to form a mold with a substantially constant axial weight balance even though the inner mold 4 has an irregular cross section.

In particular, the inner formwork 4 is built in such a way that the joint molded parts 4a, where a large amount of concrete gathers and the centrifugal force due to rotation becomes large, come into contact with the outer cylindrical form 1. The centrifugal force of 1 can be received by the outer formwork 1, and even if the inner formwork is relatively thin, it can have sufficient strength. Moreover, since the joint molding portion 4a does not bulge outward, the stability during rotary centrifugal molding, that is, the rotational balance, is affected by the mold having the joint molding portion bulging outward or between the joint molding portions. This is better compared to the case where the cylindrical formwork 1 is supported and supported at approximately the center position, and together with maintaining the strength of the cylindrical formwork 1, center runout and the like are less likely to occur.

In addition, in the present invention, the entire formwork A is
Since the centrifugal force due to rotation during centrifugal forming is supported at a position corresponding to the outer periphery of the joint forming part 4a where sagging is most likely to occur, centrifugal forming is performed, so the influence of centrifugal force is small and the concrete material filled inside is supported. Despite the irregular shape, the rotational balance is extremely good, and this is combined with the above-mentioned good axial weight balance and the reinforcing effect of bringing the joint molded portion 4a into contact with the outer cylindrical formwork 1. Extremely good centrifugal molding can be performed.

Therefore, according to the present invention, good centrifugal forming can be performed with a very well-balanced rotation and no runout, so the concrete material can be reliably filled to the ends of the joints, preventing material separation. There is no risk of antibodies becoming strain-weak, and strong, high-quality knotted concrete piles can be reliably produced.

Further, according to the manufacturing formwork of the present invention, the support position can be easily and accurately set during rotary centrifugal molding.
It is particularly suitable for manufacturing knotted concrete Pc piles because it is suitable for carrying out the above manufacturing method, and also utilizes the cylindrical formwork 1 and combines this with the inner formwork 4. It is. In other words, in a formwork with a different diameter cross section that has outwardly bulging joint forming parts, if compressive force is applied to the both ends of the formwork when tensioning the Pc steel material, there is a risk of buckling due to stress concentration at the bent part of the formwork. In the case of the present invention, the steel cylindrical formwork 1 having the same diameter over the entire length bears the compressive force,
Furthermore, since the joint molded portions 4a of the inner formwork 4 are inscribed in the cylindrical formwork 1, the burden of compressive force on the inner formwork 4 is small and there is no risk of buckling.

In addition, the formwork A is fixed by assembling and fixing the halves 4', 4' of the inner formwork 4 with the positions of the halves corresponding to each of the halves 1', 1' of the halved cylindrical formwork 1. Because of this, half-split type 1'
The half bodies 4' and 4' can be treated as one body, and by closing and opening the half molds 1' and 1', the half bodies 4' and 4' of the inner formwork 4 are also closed or opened at the same time. Even though the formwork is double-layered, the formwork can be opened and closed easily.

Furthermore, the formwork A is obtained by assembling and fixing the halves 4', 4' of the inner formwork 4 into the halves 1', 1' of the cylindrical formwork 1.
When not in use, the two halves can be fastened together with bolts, and in such a case, it is easy to assemble and disassemble, making it convenient for handling such as transportation.In particular, the inner formwork 4 can be separated into multiple pieces. In this case, the above-mentioned operation is easier and manufacturing is easier, and if the inner formwork 4 is worn and damaged, it is possible to replace only that part alone, which is economical. Further, it is convenient because several types of inner formwork 4 having different diameters can be incorporated and fixed into one cylindrical formwork 1 according to the knotted concrete pile to be manufactured.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a plan view of one half of the formwork, Fig. 2 is a sectional view taken along the line shown in Fig. 1, and Fig. 3 is another embodiment. FIGS. 4 and 5 are a partially cutaway plan view and a cross-sectional view showing the state during rotary centrifugal molding. 1...Half-split cylindrical formwork, 1', 1'...Half-split mold, 4...
Inner formwork, 4a...knot molded part, 4b...body molded part, 4', 4'...half body, 10...passive wheel.

Claims (1)

[Scope of Claims] 1. A half-split cylindrical formwork that can be opened and closed has a corresponding half-circular shape on the inside of both halves, and an inner part that constitutes the knot molding part and the body molding part. Using a formwork in which the half bodies of the formwork are assembled and fixed so that the cut surface positions correspond to the half molds and the joint molded parts are brought into contact with the inner surfaces of the half molds, A method for producing a knotted concrete pile, characterized in that it is supported at a position corresponding to the knot forming portion on the outside of the cylindrical form and subjected to rotational centrifugal forming. 2 A half body of an inner formwork that has a corresponding half circle on the inside of both halves of a half-split cylindrical form that can be opened and closed, and that constitutes a joint molding part and a body molding part. are assembled and fixed in such a way that the positions of the split surfaces correspond to the half-mold molds, and the knot molding parts are brought into contact with the inner surface of the half-mold, and the joint molding parts on the outside of the cylindrical mold are fixed. A formwork for manufacturing knotted concrete piles, which is made up of passive wheels that receive rotational power at certain positions. 3. A formwork for manufacturing a knotted concrete pile according to claim 2, wherein the knot-formed portion and the body-formed portion of the inner formwork are alternately and continuously formed over the entire length.