JPS6128817Y2 - - Google Patents

Description

[Detailed description of the invention] This invention consists of a PC strand (tensioned strand used for prestressed concrete) that is divided into several pieces in the longitudinal direction and surrounded by a wedge piece with a conical outer shape, and a truncated conical shape provided on the fixing body. This invention relates to an improvement of a fixing device that is wedged into a hole in the fixing device.

In conventional devices of this kind, as shown in Figure 1, the inner holes of the combined wedge pieces form a cylinder corresponding to the diameter of the strand, and the surface in contact with the strand is provided with a serrated ring. I'm starting to understand the strands. The tips of the teeth of the annulus form acute angles, and this part is heat-treated to have greater hardness than the PC strand. Therefore, when the wedge is strongly pressed against the surface of the strand during fixing, the tips of the teeth of the wedge dig into the surface of the PC strand, leaving a cut. As a result, the cross section of the strand is reduced in this area, making it impossible to exhibit its inherent strength, and there is also a problem in that stress concentration occurs in this flawed area, resulting in a decrease in fatigue strength. This flaw is particularly noticeable at the area where it touches the edge of the wedge.

The object of the present invention is to develop a wedge piece that compensates for the above-mentioned defects and can be manufactured at a practical cost.

The inner surface formed by bundling the wedge pieces according to the invention corresponds as precisely as possible to the shape of the outer surface of the strand. That is, a spiral groove having the same shape as the spiral formed by the outer strand of the strand is formed, and the contact surface between the wedge and the strand is made as wide as possible, thereby increasing the frictional resistance. Also, each outer strand of the strand is brought into contact with only one wedge piece. That is, each of the wedge pieces has at least one spiral groove along its entire length, and has a divided side surface to accommodate the outer strand of the strand, and the outer strand of the strand is located at the edge of the wedge piece. There is no crossing over at the ends. Furthermore, a series of recesses are provided on the bottom surface of the spiral groove of the wedge piece, so that when the wedge piece is strongly pressed onto the strand during fixing, the surface of the outer strand of the strand partially bulges into the recess of the wedge body. This prevents sliding between the wedge piece and the strand, and together with the configuration in which the outer strands of the strand do not cross the edge of the wedge piece, dangerous scars are not caused as in the case of conventional teeth, and the strand It is possible to fully demonstrate the inherent strength of the composite.

The wedge piece according to the present invention is economically advantageous because it is made of sintered metal and can be easily molded, including the formation of a recess on the inner surface, and the hardness can be adjusted to the required level. Become.

An example illustrated in the drawings will be described below.

The embodiment shown in FIGS. 2 and 3 shows the structure of a device for fixing a seven-strand strand consisting of six outer strands 2 surrounding a core wire 1 to a fixing body 3. is held by two divided wedge pieces 4 and 4' and wedged into a conical hole 5 provided in the fixing body 3.

The wedge pieces 4, 4' each have three arcuate grooves 6 for accommodating three outer strands of the strand, as shown in FIG.
, the pitch of which is formed to match the pitch of the outer strands of the strand. In this example, the outer strands were assumed to have an angular displacement of 60° over the entire length of the wedge piece. The bottom of each groove has a series of indentations 7
is provided. When the wedge piece 4 is strongly pressed against the outer strand 2 of the strand, the surface of the outer strand 2 partially bulges out into the depression 7 as shown at 8, as shown in FIG. 5, thereby forming a non-slip surface. According to experimental results, if the distance between the edges of adjacent recesses is equal to or larger than the width of the recess in the groove axis direction, no cuts will occur on the surface of the outer strand 2. The shape of the depression 7 is a circle or a horizontally elongated oval. Also, it is preferable not to provide a recess near the thinner end of the wedge piece, but rather to impregnate it with a lubricant to allow free elongation of the PC strand and to prevent breakage of the wedge piece. The wedge pieces are usually bound together at their necks by a band 9.

Although this example shows the case of a 7-strand twisted strand of strands, the present invention can also be applied to cases where the strands are twisted with 3 strands, 19 strands, etc., or when the strand itself is replaced with a strand. However, it goes without saying that the number of wedge pieces can be selected arbitrarily.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing a conventional wedge piece for fixing PC strands, Fig. 2 is a side view showing an embodiment of the present invention, Fig. 3 is a cross-sectional view of Fig. 1, and Fig. 4 is a wedge piece. FIG. 5 is an elevational view showing one piece, and a sectional view of the portion where the wedge piece contacts the strand. In the drawings, 1: Core wire, 2: Outer wire, 3: Fixing body, 4, 4': Wedge piece, 5: Conical hole, 6: Groove, 7:
It is a hollow.

Claims (1)

[Scope of utility model registration request] In a fixing device in which a PC strand is surrounded by several wedge pieces each having a conical outer shape and wedged into a truncated cone-shaped hole provided in a fixing body, the inner shape of the wedge body cannot be fixed. The length matches the outer shape of the strand, and each outer strand of the strand is 1
1. A fixing device for a PC strand, wherein the contact surface is provided with at least a series of interspersed depressions, and the wedge pieces are made of sintered metal.