JP2609347B2 - Centrifugal forming form of precast concrete tubular member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention relates to an improvement in a mold for centrifugally forming a cylindrical member made of PC (press cast cocrete) having a rectangular outer cross section.

<< Conventional Technology >> Conventionally, a cylindrical outer form having an inner space having a rectangular cross section has been driven to rotate around its axis, and the concrete put into the inner space has been subjected to centrifugal force to remove the concrete. A centrifugal molding technique for obtaining a PC cylindrical member having a rectangular cross-sectional outer peripheral shape by hardening while tightly compressing the inner peripheral surface of a mold frame is well known (JP-A-2-8011 or the like). .

<< Problems to be solved by the invention >> However, in the conventional centrifugal molding technique described above,
The outer frame is formed in the shape of a rectangular cylinder using an iron plate. However, if centrifugal force acts on the outer frame, the center of each side expands radially outward and deforms. There was a problem that it was difficult to obtain an accurate product.

The present invention has been made in view of the above circumstances, and an object thereof is to swell at the center of each side by centrifugal force when centrifugally molding a cylindrical member made of PC having a rectangular outer peripheral side in cross section. An object of the present invention is to provide a centrifugal molding form that does not cause the occurrence of cracks.

<< Means for Solving the Problems >> In order to achieve the above object, the present invention includes a cylindrical outer mold that has an internal space with a rectangular cross section and is driven to rotate around a shaft core. In the centrifugal molding form of the cylindrical member made of precast concrete, a cylindrical body surrounding the outer form is provided outside the outer form, and concrete or mortar or the like is provided between the cylindrical body and the outer form. Was filled.

<Operation> According to the centrifugal molding form of the present invention having the above configuration, the outer peripheral side of the outer form is surrounded by a cylindrical body, and concrete or mortar or the like is provided between the cylindrical body and the outer form. Since the reinforcing material is filled, the strength and rigidity of the center portion of each side of the outer mold are significantly increased. For this reason, it is possible to prevent the site from expanding radially outward due to centrifugal force during centrifugal molding,
Thus, the molding accuracy of the centrifugally molded product can be improved as much as possible.

<< Embodiment >> Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view showing a main part of a centrifugal molding form according to the present invention, FIG. 2 is a perspective view showing its appearance, and FIG.
The figure is a sectional view taken along line III-III in FIG. Fig. 1 ~
As shown in FIG. 3, the centrifugal molding form 2 has a rectangular cylindrical outer form 4 and a cylindrical body 6 surrounding the outer peripheral side of the outer form 4. And are provided coaxially.

The outer mold frame 4 is formed in a cylindrical shape having an inner space having a rectangular cross section with two congruent iron plates 8, 8 abutting each other. Each of the iron plates 8, 8 has a joining flange 8a formed at both ends thereof outwardly extending diagonally, and the joining flange 8a is overlapped to form two irons 8,.
Are divided and fastened and joined by bolts 10.

The cylindrical body 6 is also formed of two iron plates curved in a semicircular shape.
12, 12 are formed so as to abut each other. Joining flanges 12a are also formed to extend radially outward at both side ends of the semicircular iron plates 12 and 12 for the cylindrical body. The semicircular iron plates 12 for the cylindrical body are integrally joined to the iron plates 8, 8 for the outer formwork.

Then, a space defined between the outer frame 4 and the cylindrical body 6, that is, the space between the iron plate 8 for the outer frame and the semicircular iron plate 12 for the cylindrical body, which are welded to each other integrally. The space is filled with a reinforcing material 14, such as lightweight concrete or mortar.
In this embodiment, a cavity 15 is formed in the filling layer of the reinforcing member 14 for weight reduction.

Disks 16 are integrally attached to both ends of the outer mold frame 4 and the cylindrical body 6 surrounding the outer mold frame 4 in the axial direction with their centers aligned with the axis of the outer mold frame 4. In the illustrated example, a disc 16 is fitted and fixed integrally via bolts 18 to both ends in the axial direction of the cylindrical body 6. The disk 16 also serves as an end plate at both ends in the axial direction of the outer mold frame 4, and a ready-mixed concrete input port 20 is formed in a rectangular shape at the center thereof. Are determined.

Further, inside the outer mold frame 4, triangular prism-shaped inner mold frames 22 are respectively inserted and arranged along the axial direction of the outer mold frame 4 so as to face the four corners in advance. A reinforcement 24 for embedding in a centrifugally formed product is provided between the
Are arranged at appropriate intervals along the axial direction.

As shown in FIG. 3, the centrifugal molding form 2 constructed as described above has its disc 16
It is mounted so as to straddle the drive-side drum 30 and the driven-side drum 32, and is driven to rotate about its axis. At this time, a predetermined amount of ready-mixed concrete is supplied and supplied into the internal space of the outer mold frame 4 from a concrete pump (not shown) through the input port 20.

Then, the ready-mixed concrete put into the outer mold frame 4 is filled into an annular centrifugal molding space defined between the inner mold frame 22 and the outer mold frame 4 by centrifugal force. While being pressed against the inner peripheral wall surface, the excess water contained inside is discharged into the internal space and gradually compacted.The compactness of the concrete material, which is the advantage of centrifugal molding, provides a high strength and high quality cylindrical body Is solidified.

At this time, the centrifugal force acts on the outer mold frame 4 with a considerable magnitude. The outer mold frame 4 has a cylindrical body 6 surrounding the outer peripheral side thereof, and the cylindrical body 6 and the outer mold frame 4 The strength and rigidity are enhanced by the reinforcing material 14 (concrete or mortar or the like) filled in between, and the strength and rigidity particularly at the central portion of each side of the outer formwork 4 are remarkably enhanced. Therefore, unlike the related art, there is no possibility that the relevant portion expands and deforms radially outward due to the centrifugal force.
Thus, the molding accuracy of the centrifugally molded product can be improved as much as possible.

The driving drum 30 of the rotation driving device 28 is driven to rotate by a motor 36 via a belt 34.

Further, in the illustrated embodiment, the disk 16 is fitted to the cylindrical body 6 and fastened and fixed with bolts 18. However, both ends of the outer mold frame 4 are protruded from the cylindrical body 6 so that a slightly longer product is formed. Can also be formed.

<Effects> As described in detail in the above embodiments, the PC according to the present invention
According to the centrifugally molded frame of the cylindrical member, the outer peripheral side of the outer mold frame is surrounded by a cylindrical body, and a reinforcing material such as concrete or mortar is filled between the cylindrical body and the outer mold frame. The strength and rigidity of the outer mold at the central portion of each side are remarkably enhanced. For this reason, even if the centrifugal force at the time of centrifugal molding acts on the part, the part can be prevented from expanding and deforming radially outward, and the molding accuracy of the centrifugally molded product can be reduced as much as possible. Be able to improve.

[Brief description of the drawings]

1 to 4 show an embodiment of a centrifugal molding form of a cylindrical member made of PC according to the present invention. FIG. 1 is a cross-sectional view showing a main part thereof, and FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1, and FIG. 4 is a view for explaining a state in which the centrifugal molding form is placed on a rotary driving device. 2 ... centrifugal molding form 4 ... outer form 6 ... cylindrical body 14 ... reinforcing material

Claims (1)

(57) [Claims] 1. A centrifugal molding form of a precast concrete tubular member having a tubular outer form having an inner space having a rectangular cross section and being driven to rotate about an axis. A cylindrical body surrounding the outer mold is provided outside the mold,
A press-cast concrete cylindrical member formed by centrifugal molding, wherein a reinforcing material such as concrete or mortar is filled between the cylindrical body and the outer mold.