JPS6328001B2 - - 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 portion is provided that bulges outward, the axial shape of the mold becomes irregular and the structure becomes complicated. At the same time, the axial weight balance is not constant, and the rotational power from the roller on the drive shaft is Even if the receiving wheels are arranged in a well-balanced manner at the required intervals in the axial direction of the formwork, when this is used in a rotary centrifugal device such as the one described above, the presence of the joint molded portions that have a bulged shape will cause problems. As a result, the balance during rotation tends to collapse, which causes problems such as material separation and weakening of the pile body. In addition, it takes a lot of time to manufacture the forming formwork of the shape described above, which increases the cost. In addition, when manufacturing PC piles, compressive stress is concentrated at the bent part of the joint forming part that bulges when the PC steel material is tensed. This has the disadvantage that buckling is likely to occur, and reinforcing this will impair balance.

In view of the above, the present invention has provided the following features:
A thin-walled or lightweight axially deformed inner formwork for forming the knots and the body is made by halving the inner formwork by matching the cut surfaces with the half-moulds, or by making the joint part molding part into a half-mold. The axial weight balance is improved by using a special type of formwork that is assembled and fixed so that it comes into contact with the inner surface, and by considering the position of the support part of this formwork, the formwork can be received in an even better balance. The present invention aims to manufacture high-quality knotted concrete piles by supporting and performing good rotary centrifugal forming without runout, and the present invention provides a manufacturing method having the above-mentioned characteristics and suitable for carrying out the method. The aim is to provide a formwork for manufacturing.

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

In the figure, 1' and 1' are a pair of half-split 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, engagement 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. The flanges 5, 5, which are fitted inside the half molds 1', 1' and serve as mating surfaces provided on the outside of each joining end of the half bodies 4', 4', are fitted inside the half molds 1', 1'. They are fixed to the inside of the joint end by welding or by fastening with countersunk screws 6 as shown in the figure 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 formwork by using the thick wall. 1 and bolt 7 can also be tightened.

In any case, as shown in FIG. 1 or 3, the inner formwork 4 consisting of the half bodies 4' and 4' has joint molded parts 4a and trunk molded parts 4b alternately over the entire length. 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 knot 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, and on the outside of the cylindrical formwork 1 there is a half-split mold 1',
1', and when both half molds 1', 1' are closed, it becomes a ring-shaped passive wheel. The mounting position of the driven wheel 10 in the axial direction is set at the center between the joint portions 4a, 4a, as shown in the figure.
Improve your balance.

That is, in the formwork of the present invention, the axial weight balance is relatively good as described above, but when the pile is centrifugally formed, the deformed part of the inner formwork, that is, the joint forming part 4a, is filled with ready-mixed concrete C, which affects the weight balance during rotation. may be slightly distorted. Considering this and vibration transmission during rotation, the driven wheel 10 is preferably 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. The knotted concrete pile is centrifugally formed by being placed on a centrifugal device so as to be supported at substantially the center between the knotted forming portions 4a, 4a. During this molding, the half molds 1', 1' and the elongated half bodies 4', 4' of the cylindrical form 1 are opened in advance, and a core material such as a reinforcing bar cage is loaded inside. At the same time, fresh concrete is filled, and then the cylindrical formwork 1 and the inner formwork 4 are closed and fastened, and at the same time, circular lids 11, 11 are fitted to both ends of the formwork, and The formwork A in this state is placed on a rotating centrifugal device as shown in FIGS. 4 and 5 so that the driven wheel 10 is supported by the driving roller and the driven roller, and the driven wheel 10 is supported by the roller. After manufacturing, the formwork A is rotated through the mold, and rotary centrifugal molding is performed by a known method, and steam curing, curing, demolding, etc. after molding are performed in the same manner as before to manufacture the knotted concrete pile P. When the half molds 1', 1' of the mold 1 are released and divided, the inner mold 4 is opened at the same time.

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 molding part 4a and the inner mold frame 4 constituting the body molding 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-walled 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 formed at joint forming portions 4 where a large amount of concrete gathers during centrifugal forming and centrifugal force due to rotation becomes large.
a is assembled so as to be in contact with the outer cylindrical form 1, so that the centrifugal force of the joint molded portion 4a can be received by the outer form 1, and the inner form is relatively thin. It can have sufficient strength even if it is made of aluminum. Moreover, since the joint molding portion 4a does not bulge outward, the stability during rotary centrifugal molding, that is, the rotational balance, is better than that of a mold having a joint molding portion that bulges outward. Cylindrical formwork 1
Coupled with maintaining strength, it is difficult for runout to occur.

In addition, in the present invention, centrifugal forming is performed by supporting the entire formwork A at a substantially central position between the joint forming portions 4a, 4a, so that even if the concrete material filled inside is irregularly shaped, Regardless, the rotational balance is very good, and together with the above-mentioned good axial weight balance, very good centrifugal molding can be performed.

Therefore, according to the present invention, the effect of maintaining morphological stability by using the above-mentioned cylindrical formwork 1 and the well-balanced state of supporting the formwork are combined, and the rotational balance is very good and there is no runout. Good centrifugal forming can be performed without any formation of knots, and therefore the concrete material can be reliably filled to the ends of the joints, and there is no risk of material separation or weakening of the pile body, resulting in strong, high-quality joints. Concrete piles can be manufactured at a reasonable cost.

Furthermore, according to the manufacturing mold of the present invention, since the passive wheel 10 that receives rotational power is arranged approximately at the center position between the knot molding parts 4a, 4a, the setting of the support position during rotary centrifugal molding is easy. In addition to being easy and accurate, the vibrations generated during rotation transmission are not transmitted to the joints, making it possible to centrifugally form joint piles with strong joints without any material separation, making the above manufacturing method easy. And it can be carried out suitably. Furthermore, since the cylindrical formwork 1 is used in combination with the inner formwork 4, it is particularly suitable for manufacturing knotted concrete Pc piles. In other words, in a formwork with a cross-section of different diameters that has a joint forming part that bulges outward, there is a
When compressive force is applied to PC steel under tension, buckling may occur due to stress concentration at the bends of the formwork.
In the case of the present invention, the compressive force is borne by the steel cylindrical formwork 1 having the same diameter over the entire length, and the joint forming portion 4a of the inner formwork 4 is inscribed in the cylindrical formwork 1. As a result, the burden of compressive force on the inner formwork 4 is small and there is no risk of buckling.

In addition, the formwork A has half parts 4', 4' of the inner formwork 4,
Since the half molds 1' and 1' of the outer half cylindrical formwork 1 are assembled and fixed with corresponding split surface positions, the half molds 1' and the half body 4' are integrated. Both sides can be closed or opened at the same time, and even though it is made up of double molds inside and outside, it is easy to open and close the molds.

Furthermore, the formwork A, which is a combination of the cylindrical formwork 1 and the inner formwork 4, can be fastened together with bolts, and in such a case, it is easy to assemble and disassemble, and it is convenient for handling such as transportation. In particular, when the inner formwork 4 is formed separately into a plurality of parts, the above-mentioned operation is easier and manufacturing is easier, and if the inner formwork 4 is worn and damaged, only that part can be replaced, which is economical. It is. 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 halves of the formwork are assembled and fixed in such a way that the positions of the cut surfaces 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 manufacturing a knotted concrete pile, characterized in that the concrete pile is rotatably centrifugally formed by being supported at a substantially central position between the knot-formed portions on the outside of the cylindrical formwork. 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 joint molded parts are brought into contact with the inner surface of the half-split mold, and the joint molded parts on the outside of the cylindrical mold are fixed. A formwork for manufacturing knotted concrete piles, which has a passive wheel that receives rotational power placed approximately in the center of the frame. 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.