JPS6211649B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION When a metal object such as an anchor nut is embedded in a cement product that is molded in a formwork such as precast concrete, the present invention provides a method for fixing bolts for fixing the metal object, such as an anchor nut. The present invention relates to a method for removing a fixing bolt from an unhardened cement product, which allows the cement product to be removed without affecting the cement product even if the cement product is not fully hardened.

Conventionally, when embedding hardware such as an anchor nut in a cement product such as precast concrete, as shown in FIG. Anchor nut 3 with bolt 33 through
4 is embedded in the cement product 30 in a fixed state. Such anchor nut 34
In the embedding method, it is necessary to tighten the bolt 33 with considerable strength to ensure the positional accuracy of the anchor nut when pouring cement and finishing. It was necessary to wait for the product 30 to fully cure. For this reason, the production efficiency of such work was extremely low. Also, the bolt 3 is removed when the cement product 30 is not sufficiently hardened.
If the anchor nut 34 were to be removed, a large moment would be applied to the anchor nut 34, which would damage the cement product 30, which is not preferable.

Furthermore, if the production efficiency is to be increased using the conventional embedding method as described above, it is necessary to prepare a large amount of metal fittings for positioning, which is undesirable because it causes the problem of increased costs.

The present inventor has devised the present invention in order to effectively solve the above-mentioned problems, and the object of the present invention is to provide a cement material such as precast concrete in which metal objects such as anchor nuts are embedded. To provide a method for removing fixing bolts from unhardened cement products, which makes it possible to produce cement products at low cost and with extremely high production efficiency when mass producing products.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a longitudinal cross-sectional view showing a first embodiment of the engaged state of the positioning metal fitting and the embedded metal fitting in which the removal method according to the present invention can be performed.

In FIG. 1, numeral 1 is a positioning metal fitting formed in the mold 31 as described above, and 2 is a cement product that is filled into the mold 31 and hardened into a predetermined shape. Reference numeral 3 denotes an embedded metal object such as an anchor nut arranged to be embedded inside the cement product 2, and the embedded metal object 3 is formed in a cylindrical or prismatic shape and has a female thread 3a at its center shaft. It has a flange portion 3b at one end to prevent it from coming off. The embedded metal fitting 3 is screwed and fixed to the positioning metal fitting 1 by a bolt 4 inserted from the opposite side of the positioning metal fitting 1 through a hole 1a drilled in the positioning metal fitting 1. Reference numeral 5 denotes a fixing pin for regulating the rotation of the embedded metal fitting 3, and the fixing pin 5 is attached to the positioning metal fitting 1 formed so as to be at the same position at a predetermined distance from the rotation axis of the bolt 4. It is provided so as to be inserted into the hole 1b and the hole 3c of the embedded metal fitting 3 at the same time, and the embedded metal fitting 3 and the positioning metal fitting 1 are held in an engaging relationship by the fixing pin 5.

In the above, even if the cement product 2 is not completely hardened, if the embedded metal fitting 3 has hardened to the extent that its position will not change due to its own weight, then the bolt 4 can be removed using a spanner or the like. I can do it. In other words, even if the fixing bolt 4 is rotated with a spanner or the like to remove it, the fixed pin 5 keeps the embedded metal fitting 3 in an immovable relationship with respect to the positioning metal fitting 1, so the rotation moment causes the embedded metal fitting 3 to rotate. This allows the bolt 4 to be easily removed without having to do so. The fixing pin 5 is removed after the bolt 4 is removed. In this way, there is no need to wait until the cement product is completely hardened to remove the bolts 4, so the formwork 31 can be removed from the cement product 2 in a short time.

FIG. 2 shows a structure for regulating the rotation of an embedded metal object according to a second embodiment of the present invention. In this embedded metal fitting 13, cutout grooves 13b, 13b are formed in a portion of an end surface 13a that abuts the positioning metal fitting and is spaced a predetermined distance from the center line of the female thread of the embedded metal fitting 13, which is the rotation axis of the bolt 4. A protrusion 1 that fits into each of the grooves 13b, 13b is provided on the part of the positioning hardware 1 that comes into contact with this end surface 13a.
c and 1c, thereby creating an engagement relationship that restricts the rotation of the embedded metal fitting 13 when the bolt 4 rotates. The other parts are the same as the embedded metal fitting 3 described above.

In the second embodiment described above, it is also possible to produce the same effect by forming a protrusion on the side of the embedded metal piece and a groove or a recess on the side of the positioning metal piece.

As is clear from the above description, according to the present invention,
Since it is now possible to remove the bolts that fix the metal fittings embedded in the cement product in an uncured state, the fixing fittings can be easily washed with water, and the number of positioning metal fittings can be greatly reduced. Improving the production efficiency of cement products,
It has become possible to achieve cost reductions. Particularly, according to the present invention, very remarkable effects such as improvement of production efficiency can be exhibited in production methods such as the spray vibrating press method for glass fiber reinforced cement products.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view showing the engagement relationship between the positioning hardware and the embedded hardware, FIG. 2 is a diagram showing the engagement relationship according to the second embodiment, and FIG. The figure is a sectional view showing a conventional method. In the drawing, 1 is positioning hardware, 2 is a cement product, 3 and 13 are embedded hardware, 4 is a fixing bolt,
5 is a fixing pin, and 31 is a formwork.

Claims (1)

[Claims] 1. Molded in a mold 31, fixing the embedding hardware 3 to the positioning hardware 1 of the mold with bolts 4,
In a method of manufacturing a cement product such as precast concrete in which the hardware 3 is embedded during molding, the positioning hardware 1 and the embedding hardware 3 are engaged at a position a predetermined distance apart from the rotation axis of the bolt 4. A method for removing a fixing bolt from an unhardened cement product, which comprises connecting the metal fittings 3 to restrict rotation thereof, and then rotating and removing the bolts 4 in an unhardened cement state.