JPH09254120A - Method and apparatus for forming straight cylindrical hole of molded concrete product and concrete product - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To provide a hole forming technique capable of forming a large number of straight cylindrical through holes having a relatively small diameter by molding with a simple structure and forming a large number of parallel through holes. SOLUTION: A core 6 made by winding a spring wire material having a rectangular cross section in a coil shape is installed in a state of being bridged between two opposing mold members 3a, 3b for molding, and the core 6 is provided over the entire length when the mold is assembled. Contrary to compression of each ring in close contact, each ring is separated from each other when released from the mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for forming a straight cylindrical hole in a molded concrete product having a through hole, and more particularly to a method, a device and a method for forming a straight cylindrical through hole at the same time when molding a concrete product. It relates to concrete products manufactured by.

[0002]

2. Description of the Related Art When a through hole is formed in a molded concrete product, a cylindrical core is used to remove the core in the axial direction after molding. However, if the core is a straight cylinder, it is extremely difficult to remove it. Not only that, but in the case of a long through hole, it is not possible to remove the core, so it is usual to give a suitable draft to the circumferential side surface of the core, and recently, a large scale Instead of the underground buried joint groove, a simple type common groove dedicated to cables has been proposed, and a concrete perforated block is used for the simple type joint groove, but the through hole for cable insertion formed in this perforated block is a straight tube. It is also required that the through hole for cable insertion of the underground cable laying hand hole to be installed at the connection point and the branch point of the cable is also a straight tube shape.

In particular, the former, ie, the porous block, has a structure in which the through-holes of the porous block communicate with each other.
It is connected to a length of 0 to 200 m and embedded in the ground, and the power cable or communication cable is drawn into the communicating through hole. However, if the through holes of the individual blocks are tapered, the axial direction Zigzag unevenness will be formed on the cable, and when the cable is pulled in, the cable skin will rub directly against the unevenness on the inner surface of the through hole, which will damage the cable. A smooth through hole for cable insertion is required.

As a conventional core for forming a straight cylindrical through hole, a so-called split mold in which a plurality of core members including a member that moves in the radial direction are combined is generally used.

[0005]

The conventional split mold not only has a complicated structure, but also the mold assembling and demolding operations are extremely complicated, and the apparatus becomes large in size. Therefore, the split mold has a relatively small diameter. It is unsuitable for forming through-holes, and special measures must be taken when forming through-holes having a long and small diameter.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a hole forming technique capable of forming a relatively small diameter straight cylindrical through hole with a simple structure and forming a large number of parallel holes. Another object of the present invention is to provide a hole forming means capable of performing mold assembling and demolding operations easily and efficiently.

[0007]

In order to achieve the above object, the present invention uses a core made by winding a spring wire rod having a rectangular cross section in a coil shape, and when the mold is assembled, the rings are closely attached over the entire length. The main feature is that, while compressing, on the contrary, each ring is demolded under the separated state,
A core is provided in the inner cavity of the coiled core for stable shape retention before compression of the coiled core in the mold assembly.

When the coiled core is pressed against the mold assembly and compressed in the axial direction, the adjacent rings closely adhere to each other in a state of being firmly fixed by compression to form a smooth straight cylindrical core, and at the time of demolding. The coiled core is reduced in diameter as it expands in the axial direction, so that it is easy to remove the mold, and the coiled core is stably held in a straight tube shape by the core until the time of assembling the mold.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be described in detail with reference to the embodiments shown in the drawings.

As a concrete product to which the present invention is applied, for example, as shown in FIG. 5, a perforated block B having a substantially rectangular parallelepiped shape in which a large number of straight cylindrical through holes A for inserting cables are provided in parallel is adopted. Alternatively, as shown in FIG. 6, a bottomed container-like lower block C in the underground cable laying handhole having a large number of through holes A for inserting cables is formed on the side wall.

As a hole forming device for molding the straight cylindrical through hole A in the porous block B, as shown in FIGS. 1 and 2, for example, a lower mold member 1 and a double-sided mold member 2 (in the lower mold member 1) It may be integrally formed) and the front and rear end mold members 3a and 3b facing each other are mold-molded, and the cavity is filled with fresh concrete to mold the block B having a substantially rectangular parallelepiped shape. Regarding the formation of the through hole A, a circular recess 4 corresponding to the inner diameter of the through hole A is formed in the mold surface of the rear end mold member 3b, and a through hole 5 having the same diameter as the recess 4 is formed in the front end mold member 3a. A core 6 produced by winding a metal spring wire having a rectangular cross section on the common axis and having an outer diameter equal to the inner diameter of the through hole A.
A cylindrical shape in which the inner ring 6 is pressed from the outside of the front end mold member 3a and the adjacent rings are firmly fixed by compression while the core 6 is installed in a spanning state over the recess 4 and the through hole 5. To hold.

As the compression mechanism 7 for pressing the core 6 from the outside of the front end mold member 3a, for example, a pressing member 8 is brought into contact with the base end of the core 6 and a tightening screw 9 is screwed. The holding arm 10 is pivotally supported on the front end type member 3a by a pin 11 at its base, and the tip of the bifurcated arm is hooked by a tiltable eyebolt 12 so that the holding arm 10 can be tightened. With the tip of the attachment screw 9 standing upright in contact with the center of the outside of the pressing member 8, the arm tip is hooked by the tiltable eyebolt 12 and then the pressing screw 9 is screwed into each pressing member. The core 6 is compressed via 8.

In the hollow portion of the core 6, the core shape retaining core 1 is formed.
It is appropriate to provide 3 in a loosely fitted state, and it may be provided by being fixed to the pressing member 8. Further, a slightly larger cylindrical guide receiving portion 14 is formed outside the through hole 5 in the front end mold member 3a. At the same time, the pressing member 8 has a guide receiving portion 14
It is desirable to provide a skirt portion 15 that slides in the direction so that the tip of the core 6 can easily go straight into the recess 4 of the rear end die member 3 when hitting the die assembly.

The tightening / loosening operation of the tightening screw 9 may be performed by an impact wrench, or a handle may be fixed to the head of the tightening screw 9 and manually operated. As the pressing means of 6, the tightening screw 9
Not limited to this, various means such as a cam, a toggle, a cotter, and a lever type mechanism can be adopted.

Instead of the recess 4 in the rear end mold member 3,
A through hole similar to that in the front end mold member 3 may be formed, and a receiving member that receives the tip of the core 6 may be fixed to the outside of the through hole.

In actual die assembly, first, the lower die member 1
After assembling the two side mold members 2 and the front and rear end mold members 3a, 3b as shown in FIG. 1 by a mold clamping mechanism (not shown), the core 6 is applied to the pressing member 8 from the outside of the front end mold member 3a. After inserting the tip end of the core 6 into the concave portion 4 of the rear end mold member 3b while inserting the insertion arm into the through hole 5 with the insert arm inserted, and raising the holding arm 10 to hook the tip to the eyebolt 12. , Holding arm 10
The core 6 may be compressed by screwing in each of the tightening screws 9 in FIG. 2, and the core 6 may be preassembled on the front end mold member 3a and then the double-end mold members 3a and 3b may be assembled. Of.

The cavity formed by the mold assembly is filled with ready-mixed concrete and is demolded through a normal molding process such as compaction and curing. In the reverse order, as shown in FIG. 2, the holding arm 10 is removed, and then the core 6 is pulled out. In this pulling-out process, the diameter is reduced as the core 6 is extended. It is easy to pull up and pull out, and after that, the side mold member 2 and the end mold members 3a and 3b
Demold. Note that the mold release of the core 6 and the mold release of the side mold member 2 and the end mold members 3a and 3b may be performed in the reverse order.

In the embodiment shown in FIG. 3, the core 13 is fixed to the front end mold member 3a by screwing or the like, and the core 6 is fixed to the front end mold member 3a at the base thereof. The core 6 may be assembled at the same time as the mold assembly, and the core 6 may be removed at the same time as the end mold members 3a and 3b.

Regarding the molding of the lower block C in the handhole of FIG. 6, there is no difference in properties from the device for forming the through hole A in the porous block B, that is, FIG.
As described above, the lower mold member 1, the inner mold member 3a, and the outer mold member 3b are assembled into a mold, and the cavity is filled with ready-mixed concrete to mold the container-shaped lower block A. 3b is the same as that in the embodiment of FIGS. 1 and 2, except that the relationship of 3b is different between before and after or inside and outside, and therefore, the same reference numerals are given to the same portions and the description thereof will be omitted.

In the above-described embodiments, the core 6 is a kind of coil spring, and may be a compression spring type that is slightly coiled in addition to the close coil type tension spring type. In the case of the tension spring type, In contrast, the core 6 is demolded while being stretched, whereas in the case of the compression spring type, the core 6 is stretched and demolded while being expanded by the restoring force of the core 6 itself.

The above-mentioned embodiment is a case where the present invention is applied to the formation of the perforated block for laying an underground cable and the cable insertion hole in the hand hole, but the present invention is applied to the molding of the hole in other concrete products. It goes without saying that the shape of the molding hole is not limited to the cylindrical shape, and can be applied to the molding of various cylindrical holes such as a triangle, a square, a rectangle, other polygons, and an oval. Is.

[0022]

As described above, according to the present invention, the following effects can be obtained.

A core 6 made by winding a spring wire having a rectangular cross section into a coil shape is used. When the mold is assembled, the rings are compressed so that the rings closely contact each other, while the rings are separated from each other. Since the mold 6 is demolded, the core 6 can be easily demolded by utilizing the phenomenon that the outer diameter when expanded is slightly smaller than the outer diameter when compressed. Since the forming material of the core 6 has a rectangular cross section, the outer shape of the core 6 forms a smooth cylindrical surface to form the through hole A on the smooth inner surface, and is convenient for demolding.

Further, by providing the core 13 inside the core 6, the core 6 can be maintained in a stable straight tube shape before and during the mold assembly, and therefore, the core 6 and the mold can be assembled during the mold assembly. The fitting with the member 3b is easily performed.

Since the molding can be carried out with a remarkably simple structure employing the coil spring type core 6, for example, when molding a relatively small hole having a diameter of 10 cm or less to a length of several tens of cm or more. In addition to being applicable, it is convenient when molding a plurality of small-diameter holes in a juxtaposed state in a juxtaposed manner, and is therefore optimum for forming holes in a perforated block for laying underground cables and hand holes.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional side view of a mold for assembling a perforated block molding frame to which a straight cylindrical hole forming device of the present invention is applied.

FIG. 2 is a vertical sectional side view of a main part of a demolding process of the apparatus of FIG.

FIG. 3 is a vertical cross-sectional side view showing a molding frame of another embodiment to which the straight cylindrical hole forming device of the present invention is applied before mold assembly.

FIG. 4 is a vertical cross-sectional side view of a mold for assembling a handhole molding frame to which the straight cylindrical hole forming device of the present invention is applied.

FIG. 5 is a perspective view showing a perforated block for laying an underground cable molded according to the present invention.

FIG. 6 is a perspective view showing an underground cable laying handhole molded according to the present invention.

[Explanation of symbols]

 3a type member 3b type member 6 core 7 compression mechanism 12 core A through hole

Claims (4)

[Claims] 1. A method for forming a through-hole (A) in the shape of a straight tube at the same time as molding of a concrete product, using a core (6) produced by winding a spring wire rod having a rectangular cross section in a coil shape, A method for forming a straight cylindrical hole, characterized in that, when assembled, each ring is compressed so as to be in intimate contact over its entire length, and on the contrary, each ring is demolded under a separated state. 2. A device for forming a through-hole (A) in the shape of a straight tube at the same time as molding a concrete product, wherein a core (6) manufactured by winding a spring wire rod having a rectangular cross section in a coil shape is used as a mold member (3a). ) And (3b), and is provided with a compression mechanism (7) for pressing the core (6) so that the rings are in close contact with each other over the entire length when the mold is assembled. Forming equipment. 3. A core (1) is provided inside a coiled core (6).
The straight cylindrical hole forming device according to claim 2, wherein 2) is provided in a loosely fitted state. 4. A concrete product molded by the straight cylindrical hole forming device according to claim 2 or 3.