JP2005248473A - Structure of embedded form holder made of concrete - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure of an embedded form holder made of concrete, capable of reducing damage of the holder itself caused by a frequently generating projection of the embedded form holder and tightening when installing a form, in a construction method for manufacturing a concrete structure by using the embedded form holder. <P>SOLUTION: This structure of the concrete embedded form holder is formed into a structure for embedding a fiber sheet formed of nonwoven fabric inside the embedded form holder, by reducing the projection of the embedded form holder generated by the fastening-in when installing the form, by setting the area of a form grounding surface to 550 mm<SP>2</SP>or more; and can prevent the damage by compressive force by the tightening and action force generated when rotating a metallic nut embedded inside the embedded form holder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a concrete embedded mold holder used for producing a concrete structure using a mold, and more particularly, to hold a mold at a predetermined interval when placing concrete. The present invention relates to the structure of a concrete embedded mold holder which is attached to both ends of a separator for fixing a mold used in the above.

  Conventionally, there are two types of mold holders used for assembling concrete molds at regular intervals: one that can be embedded and one that is removed after placement. It has been added.

  As a means to keep the distance of the formwork constant, a method of attaching long bolts called separators to the formwork at regular intervals is often used, and in order to fix this separator, it is made of plastic with embedded connection nuts It is common practice to use a formwork holder. However, when this method is used, it has been necessary to perform complicated repair work such as repairing the trace of the mold holder that remains on the finished surface after demolding the concrete mold using mortar or the like.

In recent years, the above-described repair work can be eliminated, and furthermore, there is a construction method using an embedded mold holder for the reason that industrial waste is not generated even at the time of final disposal of the removed instrument. It has been adopted.

  Typical embedding mold holders include plastics of the same color as concrete and those made of concrete or mortar as the main material. When using a formwork holder, there is a concern that water leaks from the gap between the holder left in the concrete and the intrusion of rain, and rainwater enters, which adversely affects the concrete structure.

Further, when an impact wrench or the like is used to fix the above-described embedded form holder, the embedded form holder retains the plywood formwork due to excessive compressive force or rotational force caused by tightening. When the formwork is removed after the placement, there is a case where the embedded formwork holder protrudes from the finished surface and forms a convex portion, which requires repair work. Moreover, in the formwork holder made of concrete, there are many problems that the holder itself is damaged due to excessive tightening.

  The concrete embedded mold holder according to the present invention is difficult for the holder to bite into the plywood mold even when the mold is attached, and to the compressive force and rotational force generated during tightening. Another object is to produce and provide a concrete formwork holder having a structure in which the holder itself is not easily damaged.

  As a structure of a concrete embedded formwork holder for solving these problems, the compressive force applied to the formwork grounding surface is reduced, and the embedded formwork holding caused by tightening when the formwork is assembled. As a means to reduce the protrusion of the tool and prevent damage due to the action force generated when trying to rotate the metal nut embedded in the holder, it is excellent in tensile strength and tear strength, thin and lightweight Providing a concrete formwork holder with a structure that prevents the holder itself from being damaged by embedding a non-woven sheet made of fiber as a material with high adhesion to concrete and does not adversely affect the concrete. can do.

According to the invention mold footprint according to implantable mold coercive claim 1 which is 500 mm ² or more, in fabricating the concrete structure using a lifting tool, the tightening torque by conventional impact wrench, etc. That is 1200 Kgf / If the construction is performed at cm ² or less, it is possible to obtain a uniform finished surface having no convex portion on the concrete finished surface.

  According to the second aspect of the present invention, it is possible to manufacture a concrete embedded formwork holder that is less damaged by tightening when assembled to the formwork.

Hereinafter, preferred embodiments of the present invention will be described in detail.
FIG. 1 shows a typical structure of a generally known concrete embedded mold holder, which is a separator d. And shaft foot e. Metal nut for connecting a. Is the concrete part b. Embedded in the mold ground contact surface c. All the compression force generated by tightening is applied to. Thus, a plywood formwork h. As a result, the embedded formwork holder is recessed and the formwork grounding surface c. Because of the frictional force, the buried metal nut a. The radial part of the concrete part b. In addition, the holder itself is also damaged.

Conventional embedded form holders have a mold ground contact surface c. Is very small, and the compressive force acting on the mold is locally increased. In addition, the force applied when tightening with an impact wrench is about 1200 Kgf / cm ² or less, but the force concentrates only on the formwork grounding surface c. Therefore, the force per 1 mm ² changes as the site area changes. It will be.
However, it is preferable to make the outer shape of the embedded mold holder as small as possible in consideration of work efficiency.

Accordingly, in the present invention, a compression force of 1200 kgf / cm ² is applied to a commonly used 12 mm thick plywood formwork to change its area, and the effect on the plywood is examined to hold the embedded formwork. We decided to examine the formwork contact surface c.

Area to apply a compressive force, when ^{250mm 2 · 300mm 2 · 350mm 2} · 400mm 2 · 450mm 2 · 500mm 2 · 550mm 2 · 600mm and eight of ² can 0.2mm or more concave plywood and rejected did.

Table 1 shows the above-mentioned results. In all cases, a recess of 0.2 mm or more was generated and rejected at 500 mm ² or less.

From this experimental result, if the area of the embedded mold holder that is in contact with the plywood mold is 500 mm ² or more, the mold holder can bite into the mold and reduce the protrusions that appear on the finished surface. Therefore, the diameter of the mold ground contact surface of the concrete embedded mold holder of the present invention is set to 30 mm, and the shaft foot e. Even if a cavity with a diameter of 14 mm, which is a hole through which a hole is passed, is subtracted, the effective area is 552.64 mm ² .

  Next, in order to reduce the damage caused by tightening the concrete embedded form holder, the concrete part b. Metal nut to be embedded in a. A fiber sheet made of non-woven fabric is used as an aggregate to increase strength around the f. By cutting and setting into a circular shape and embedding it, the compressive force due to tightening and the radial action force generated when the metal nut embedded in the embedded formwork holder tries to rotate are suppressed. Is possible.

As a concrete manufacturing method of the concrete embedded form holder according to the present invention, as shown in FIG. Metal nut a. Fiber sheet made of non-woven fabric in the middle part of f. , Mortar and the like poured into the mold, and after curing for a certain period of time g. It is completed by taking out more.

In the present invention, a thin and lightweight high-performance nonwoven fabric made by DuPont Co., Ltd., which is excellent in tensile strength and tear strength, is adopted, but it is made of a material that does not affect the concrete well and has the same performance. If it has, it can be used conveniently.

It is the figure showing the structure of the general concrete formwork holder, and the condition where this was assembled to the concrete formwork. It is a figure showing the structure of the concrete-made frame holder strong to the damage by clamping | tightening based on embodiment of this invention. Mold and mechanism for producing a concrete formwork holder according to the present invention.

Explanation of symbols

a. Metal nut for connecting shaft foot and separator
b. Concrete body part of concrete embedded formwork holder
c. Formwork grounding part of embedded formwork holder
d. separator
e. Pivot foot
f. Non-woven fiber sheet
g. Mold for making concrete formwork holder
h. Plywood formwork

Claims (2)

When a concrete structure is manufactured using an embedded formwork holder, it prevents the phenomenon that the holder bites into the formwork by tightening the home tie and the holder protrudes on the finished concrete surface. Structure of embedded formwork holder made of concrete that can be used as a surface When fixing a concrete embedded form holder to a formwork, damage to the holder itself, such as cracking of a concrete embedded form holder, which is caused by compressive or rotational force due to tightening, is greatly reduced. The structure of an embedded formwork holder made of concrete.

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