JPH0336964B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) This invention is an end metal fitting used to latch and support the latch head of a tension wire buried inside a concrete pile or column. The present invention relates to a method for forming a through hole.

(Prior Art) Conventionally, this type of end fitting has been fixed to the end face of a concrete pile 21, for example, as shown in FIG. and,
Both ends of the tension wire 22 buried inside the concrete pile 21 are hung through a plurality of through holes 24 provided in the end metal fitting 23 and the end metal fitting (not shown) fixed to the other end surface of the concrete pile 21. The tensile strength of the concrete pile 21 is reinforced by supporting the concrete pile 21 and tensioning the tension wire 23.

As shown in FIG. 12, the through hole 24 of the end face fitting 23 is connected to the hooking head 22a of the tension wire 22.
A latching hole 2 provided with a stepped portion 25a for latching the
5, a screw hole 28 for screwing a bolt 27 supported by a support plate 26 disposed at an end of a concrete pile manufacturing drum (not shown) in the manufacturing process of the concrete pile 21; A communication groove 29 communicates between the holes 25 and 28.

However, since the locking hole 25 and the screw hole 28 communicate with each other in the through hole 24, a decrease in strength was inevitable, particularly in the vicinity of the communicating groove 29. Therefore, in order to avoid deformation in the vicinity of the through hole 24 of the end fitting 23 and to maintain sufficient tension of the tension wire 22, the plate thickness of the end fitting 23 must be increased, which inevitably causes the product to deteriorate. This led to an increase in costs.

Therefore, in order to solve the above-mentioned problems, the applicant of this invention filed Japanese Patent Application No. 60-52904.
The end fitting described in the specification and drawings attached to the application in No. 2 was proposed.

As shown in FIGS. 13 and 14, the through hole 31 of the end fitting 30 described in the above specification and drawings is formed through press molding by the cooperation of a male mold 32 and a female mold 33. . That is, male mold 3
2 includes a locking hole 34, a screw hole 35, and both holes 3.
Bottomed hole 3 for forming communication grooves 36 of 4 and 35
A convex portion 32a for press-molding 1a at the same time is provided, and a recessed hole 33a corresponding to the convex portion 32a of the male mold 32 is provided in the female mold 32. Then, as shown in FIG. 13, the metal of the end fitting 30 is pressed by the cooperation of both the molds 32 and 33, and the bottomed hole 31a is formed so that its side edge protrudes thickly in the pressing direction. Form it like this. Next, both molds 32,
The bottom wall portion 37 of the protruding portion 38 that was press-molded by the method 33 was cut out, and the through hole 31 was formed therethrough.

(Problems to be Solved by the Invention) However, as shown in FIG. 13, in the process of forming the through hole 31 of the end face fitting 30, there are If the parts were press-molded at the same time in a communicating state, there were cases where a sagging deformation Q occurred in the pressing direction that did not match the mold shape at the upper end of the opening of the part corresponding to the locking hole 34 and the screw hole 35. In this way, if the sagging deformation Q occurs, not only will it be difficult to cut the internal thread in the threaded hole 35 smoothly in the subsequent process, but also if the sagging deformation Q occurs near the communication groove 36, the tension wire 22 will not be cut smoothly. Even if the latching head 22a was latched within the latching hole 34, there was a risk that it would fall off from the stepped portion 34a due to the tension of the tension wire 22.

The present invention has been made in view of the above-mentioned circumstances, and is intended to prevent sagging deformation at the upper end of the inner periphery of the locking hole and screw hole that constitute the through hole when press-molding the through hole of the end face fitting. The purpose of the present invention is to provide a method for forming a through hole in an end fitting used in a concrete pile or column, which can reduce the thickness of the end fitting and improve the strength near the hole.

Structure of the Invention (Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a method of simultaneously press-molding a pair of bottomed holes, one for a hanging hole and one for a threaded hole, in a separated state. to form a stepped portion on the inner periphery of the bottomed hole for the latching hole, and then connect both the bottomed holes and cut out the bottom wall portions of both the bottomed holes,
Next, a configuration is adopted in which a female thread is formed in the through hole of the bottomed hole for the screw hole.

(Function) Therefore, the pair of bottomed holes for the locking hole and the screw hole are press-molded in a separated state.
At this time, the metal pressed in the pressing direction is deformed in a distributed manner within both bottomed holes, so that large deformation of the metal in the pressing direction is prevented. For this reason, sagging deformation in the pressing direction at the opening upper ends of both of the bottomed holes is prevented. As a result, the female thread can be easily threaded in the threaded hole without sagging deformation, and the latching head of the tension wire is reliably prevented from falling off at the stepped portion of the latching hole without sagging deformation.

In addition, the side edges of the latching holes, screw holes, and their communication grooves are molded to protrude thickly in the pressing direction, so that
The strength near the through hole is improved.

(Example) Hereinafter, an example in which the present invention is applied to the formation of a through hole in an end metal fitting for a concrete pile is shown in Figs.
This will be explained in detail based on FIG. 9.

As shown in FIG. 1, an end face fitting 1 disposed on the end face of a concrete pile (not shown) is composed of an annular bottom plate part 2 and a substantially cylindrical side wall part 3. In the bottom plate portion 2, there are a plurality of through holes 7 arranged at equal intervals in the circumferential direction and each consisting of a locking hole 4, a screw hole 5, and a communication groove 6 that communicates between the two holes 4 and 5 (this embodiment 6) are provided. Further, the side wall portion 3 is provided with a welding groove 3a for welding connection to the side edge portion of another end fitting, and a reinforcing ring 8 is fitted and fixed therein.

Furthermore, as shown in FIG.
A thick protrusion 9 is integrally provided on the inner surface of the bottom plate portion 2 along the side edge of each of the through holes 7.

Next, a method of forming the through hole 7 of the end fitting 1 will be explained.

The through hole 7 is formed through press molding by cooperation of a male mold 10 and a female mold 11 as shown in FIGS. 3 and 4.

As shown in FIGS. 3 and 5, the male mold 10 includes a convex portion 10a for a stepped portion 4a (shown in FIG. 7) provided in the locking hole 4, and a tension wire 12 (shown in FIGS. 8 and 9). (Illustrated) A convex portion 10b for insertion is provided.
Further, a protrusion 10c for the screw hole 5 is provided in a separated state from the protrusion 10b via a protrusion 10d for the thick portion 13 (shown in FIG. 6) corresponding to the communication groove 6. . The convex portion 10d is press-molded so that the upper end of the thick portion 13 is located above the lower end of the stepped portion 4a and below the opening upper end of the locking hole 4. There is. Further, a chamfered portion 10e having a larger inclination angle than the distal end portion is provided at the base end portion of the convex portion 10a.

On the other hand, as shown in FIGS. 4 and 5, the female mold 1
1 is provided with a recessed hole 11a. The tops of both the convex portions 10b and 10c are formed to have substantially the same height, and are set to be smaller than the sum of the thickness of the bottom plate portion 2 and the depth of the recessed hole 11a.

Therefore, in order to press-mold the through hole 7 using both the molds 10 and 11, first, as shown in FIG. 5, the bottom plate part 2 of the end fitting 1 is placed on the female mold 11, As shown in FIG. 6, the male mold 10 is moved down and the bottom plate portion 2 is compressed by the cooperation of the male mold 10 and the female mold 11. As a result, the metal of the bottom plate portion 2 that is squeezed between the convex portions 10a to 10d, etc. of the male mold 10 and the concave hole 11a of the female mold 11 is
10d etc. and the side surface of the recessed hole 11a, and the protrusion 9 is moved along the side edge of the through hole 7.
is formed protrudingly with considerable thickness. Further, a slightly thick bottom wall portion 2 is formed between the tips of both convex portions 10b and 10c and the bottom surface of the recessed hole 11a.

That is, as shown in FIG.
A protrusion 9 is formed to protrude in the press direction between the bottom plate 2 and the bottom plate 2 without being penetrated. At the same time, a pair of bottomed holes 4b and 5a for the locking hole 4 and the screw hole 5 are press-molded in a separated state via the thick portion 13 by both convex portions 10b and 10c, respectively. Therefore, the metal of the bottom plate portion 2 that is pressed and moved in the pressing direction is moved in a distributed manner to both the bottomed holes 4b and 5a, so that large deformation in the pressing direction is suppressed. As a result, both the bottomed holes 4
At the upper end portions of the openings b and 5a, sagging deformation in the pressing direction is prevented. In this way, the bottomed holes 4b and 5a for the locking hole 4 and the screw hole 5, and the recess 6a for the communication groove 6 are press-molded, respectively, and the stepped portion 4a is formed in the bottomed hole 4b. Ru.

Thereafter, the protruding portion 9 is molded to protrude in the pressing direction.
The bottom wall portion 2a is cut out to fit the bottomed holes 4b, 5a to pass through the bottomed holes 4b, 5a, and the thick portion 13 is cut out to form the communication groove 6. Next, a female thread 14 is carved inside one of the bottomed holes 5a that has been penetrated.

In this way, as shown in FIG. 8, a through hole 7 is formed, which is constituted by a locking hole 4 having a stepped portion 4a, a screw hole 5, and a communication groove 6 between the holes 4 and 5. is completed. Further, other through holes 7 are formed by the same method.

As mentioned above, in this embodiment, when forming the through hole 7, the bottomed holes 4b and 5a for the locking hole 4 and the screw hole 5, which constitute the through hole 7, and the recess 6a for the communicating groove 6 are , are simultaneously press-molded by the cooperation of the male mold 10 and the female mold 11, respectively. Also, the bottom plate portion 2 of the end fitting 1 is compressed during the press molding.
is molded to protrude in the pressing direction along the side edge of the through hole 7, and the bottom wall portion 2a of the protrusion 9 is press molded to be thinner than the thickness of the bottom plate portion 2. Therefore, it is possible to easily penetrate the bottom wall portion 2a, which has a reduced thickness.

Also, during press molding, both the bottomed holes 4b and 5a for the locking hole 4 and the screw hole 5 of the through hole 7 are connected to the thick wall portion 13.
molded in a separated state through the Therefore, the first
Unlike the conventional examples shown in Figs. 3 and 14, when the locking hole 34 and the screw hole 35 are formed to communicate without providing a thick wall part, the upper end of the opening of the through hole 31 sags in the pressing direction. No deformation Q occurs.

Furthermore, since the sagging deformation Q is prevented, the threaded hole 5 with the internal thread 14 can be easily formed by thread cutting.

In order to hang a plurality of tension wires 12 in the hanging hole 4 of the through hole 7 formed in this way, after inserting the hanging head 12a of the tension wire 12 into the screw hole 5,
The end fitting 1 is rotated around its axis. Then, as shown in FIG.
The latching head 12a may be latched to the latching head 12a. The tension wire 12 suspended in this manner is tensioned by adjusting bolts supported by support plates disposed at both ends of a drum for manufacturing concrete pipes into screw holes 5.

Further, according to the end fitting 1 of this embodiment, the through hole 7 for latching and supporting the latching head 12a of the tension wire 12 is provided.
Since the inner circumferential surface of the protrusion 9 is formed with a considerable thickness, the strength near the through hole 7 is greatly increased. Therefore, even if an end fitting that is thinner than the plate thickness of a conventional end fitting without a protrusion is used, the strength near the through hole 7 can be secured to the same level as the strength near the through hole of a conventional end fitting. . As a result, even if a conventional tension is applied to the tension wire 12, deformation in the vicinity of the through hole 7 is prevented.

Reducing the thickness of the end fitting allows the use of materials and costs to be reduced, and also facilitates press molding, which further facilitates the formation of the through hole 7.

Note that the present invention is not limited to the above-mentioned embodiments; for example, as shown in FIG. 10,
When press-molding the bottom plate portion 2 of the end fitting, the two convex portions 10 correspond to the convex portions 10d of the male mold 10.
A convex portion 1 that fits between b and 10c correspondingly.
1b may be provided in the concave hole 11a of the female mold 11, etc., as appropriate without departing from the spirit of the invention.

In the above case, since the thickness of the thick portion 15 is smaller than the thick portion 13 of the embodiment described above, the thick portion 15 can be easily removed.

Effects of the Invention As detailed above, the present invention enables press molding by preventing the upper end of the opening of the through hole from sagging deformation in the process of forming the through hole of the end metal fitting, and allows the end metal fitting to be made thinner and transparent. It has the excellent effect of improving the strength near the hole and forming a through hole that facilitates female thread cutting and securing of tension wire.

[Brief explanation of the drawing]

1 to 9 show an embodiment embodying the present invention, FIG. 1 is a perspective view of the end fitting, FIG. 2 is a perspective view showing the inside of FIG. 1, and FIG. 3 is a male metal fitting. Figure 4 is a bottom view of the mold, Figure 4 is a plan view of the female mold, Figure 5 is a front view of the male and female molds, Figure 6 is a front cross-sectional view showing the pressed state, and Figure 7 is the state after pressing. FIG. 8 is a front sectional view showing a main part of the end fitting, FIG. 8 is a front sectional view of the through hole that has been formed, and FIG. 9 is a sectional view taken along the line X--X in FIG. 8. FIG. 10 is a sectional view showing another example. Furthermore, Fig. 11 to Fig. 14 show the prior art, Fig. 11 is a broken perspective view of a concrete pile, Fig. 12 is a partial sectional view of a through hole of an end fitting, and Fig. 13 is a normal cross section showing a pressed state. 14 are front sectional views showing essential parts of the end fitting. 1... End metal fitting, 2... Bottom plate part, 4... Latching hole, 4a
...Stepped portion, 5...Screw hole, 6...Communication groove, 7...Through hole,
9...Protrusion part, 10...Male mold, 10a, 10b, 1
0c, 10d...Convex portion, 11...Female mold, 11a...Concave hole, 12...Tension wire, 12a...Latching head, 13
...thick part, 14...female thread.

Claims (1)

[Claims] 1. A latching hole 4 with a stepped portion 4a for latching and supporting a latching head 12a of a tension wire 12 buried inside a concrete pile or pillar, etc., and a bolt. In the method for forming the through hole 7 of the end face fitting 1, which is constituted by the screw hole 5 for screwing the At the same time, a step part 4a is formed on the inner periphery of the bottomed hole 4b for the hooking hole 4 by press molding, and then both the bottomed holes 4b and 5a are communicated with each other, and the bottom walls of both the bottomed holes 4b and 5a are connected. A method for forming a through hole in an end metal fitting for use in concrete piles or columns, etc., comprising cutting out the portion 2a, and then forming a female thread 14 in the through hole of the bottomed hole 5a for the screw hole 5. 2 The latching hole 4 and the screw hole 5 have a thick wall portion 13 having an upper end located above the lower end of the stepped portion 4a of the latching hole 4 and below the upper end of the opening edge of the latching hole 4. A method for forming a through hole in an end fitting used in a concrete pile or column as claimed in claim 1, wherein the hole is press-molded in a spaced state through a hole.