JPS5890335A - Locking method for pc steel - Google Patents

Abstract

PURPOSE:To facilitate locking of PC steel to a tension plate by fitting a nut to the end of the PC steel having no screw, bringing a push electrode into contact with the end face, and heating by applying current, and thereby fitting the end of the PC steel into the slot inside of the nut simply. CONSTITUTION:A round bar PC steel 1 having no screw at the end is put between receiving electrodes 3 and inserted into a nut 2 held by a push electrode 5 near its end face, and brought into contact with the end face of the push electrode 5. Then, the steel material 1 is held by thrusting the movable side of the receiving electrodes against fixed side by a hydraulic cylinder 4. Current is applied between the two electrodes while pushing the end face of the steel material 1 by the push electrode 5 to the receiving electrode 3 using a hydraulic cylinder 6. By this way, an end of the steel material is heated and swells into the slot of the nut 2, and fitted to the nut 2. Under this condition, the electrode is removed and the PC steel material 1 is locked to a tension plate 7 by the nut 2.

Description

Detailed Description of the Invention This invention provides a method for introducing prestress into concrete when manufacturing prestressed concrete members.
This invention relates to a method of locking a steel material to a tension plate so that it can be maintained under tension.

When manufacturing prestressed concrete members such as concrete balls and restless concrete balls, tensed steel is buried in concrete.1. If the tension is released after the concrete has hardened and prestress is applied to the concrete by the contractile force of the steel through the adhesive force between the concrete and the steel, the end of the steel is locked to the tension plate and the steel is held until the concrete hardens. Holds tension. In order to hold the steel material in a tensioned state, the wire diameter of the steel material is relatively large, and a screw is formed on the end of the steel material, inserted into a hole provided in the tension plate, and fitted with a nut, which is then locked to the tension plate with the nut. However, if the wire diameter of the steel material is relatively small, it is easier to insert the steel material into a hole in the tension plate, form the insertion end into a rivet head-like shape with an electric upsetter, and lock it to the tension plate. . However, in order to release the tension applied to the steel material after concrete hardens, it is necessary to form the ends of the steel material, cut off the caps, and heads using a gas burner or chisel, which reduces work efficiency and work safety. However, it is an object of the present invention to provide a method for locking a PO steel material to a tension plate, which solves this problem.

In order to achieve this object, the present invention fits a nut into the end of the PO steel material that does not have a thread, brings the nut and the end surface of the PO steel material into contact with a pushing electrode, Hold the PC steel material between the electrodes, heat the end of the pom material by passing electricity between the receiving electrode and the pushing electrode, and push the pushing electrode toward the receiving electrode.
The outer circumference of the PC steel end is enlarged in the thread groove on the inner surface of the nut, and the pa
The sound comes from removing the w material from the receiving electrode and pushing electrode and locking the nut at the end of the patii material to the tension plate. The invention will now be described with reference to examples.

As shown in FIGS. 1 and 2, a PO steel material l made of a round rod with a diameter of about 100 mm and no screws at the end is inserted between the receiving electrodes 3, and is placed in contact with the end surface of the pushing electrode 5. The receiving electrode 3 was inserted into a naratoko supported by the holder, and was brought into contact with the end face of the pushing electrode S, and the movable side of the receiving electrode 3 was pressed against the fixed price by a hydraulic cylinder, so that the receiving electrode 3 clamped the PO steel material 1. At this time, the distance between the Naratoco and the receiving electrode 3 is '1m 5'' %The distance from the receiving electrode 3 to the pushing electrode S Ml / 7-'!r The height of the seagull, the height of the Naratoco / 3 Kami, the inner diameter of the Naratoco, 3 m , Natsu) J screw bottom diameter //'Inm.Next, while pushing the end face of the PO steel l toward the receiving electrode 3 with the hydraulic cylinder 6 & pushing electrode 5, electricity is applied between the pushing electrode S and the receiving electrode 3. The end of the PC steel material was heated to about SOC, and the pressing force of the pushing electrode S was further increased to enlarge the outer periphery of the end of the PC steel material into the thread groove on the inner surface of the Naratoco.

Attach a Naratoco to the end of the PC steel material and take out the PCG material from the receiving electrode 3 and pushing electrode S as shown in Fig. 3.
As shown in FIG. 9, insert the PO steel l into the tension plate 7 by inserting it into the hole provided in the tension plate 7 and lock it with the tension plate 7.
A naratoko is attached to the end of the ll#/ as described above, and the naratoko is engaged with the tension plate 7.

In the method of the present invention, the reason why the Naratoco is brought into contact with the pushing electrode S and processing is started with a gap between the Naratoco and the receiving electrode 3 is that the side of the PO steel l that is in contact with the pushing electrode S is heated by the receiving electrode 3 due to contact resistance heat. , the temperature rises earlier than the side, so if there is a gap between the Naratoco and the pushing electrode S, the POm material/ will swell like a rivet head between the Naratoco and the pushing electrode S, causing the thread groove of the Naratoco to swell. Because the expansion of the outer periphery of the PO steel material is incomplete or not performed,
Also, if a bulge occurs when removing the Naratoco, it cannot be removed, so to prevent this from occurring, the Naratoco is brought into contact with the pushing electrode S, and expansion is performed from the pushing electrode S side to the thread groove on the outer circumference of the PO steel material. This is to ensure that. Furthermore, the distance between the Naratoco and the receiving electrode 3 provides an allowance for expansion of the PC#I material 1 into the thread groove. Therefore, the Naratoco may be simply inserted into the end of the PCG material l and placed in contact with the pushing electrode S, or it may be detachably held in contact with the pushing electrode S by a holding member provided with the pushing electrode Sε. It's okay. 7. According to the method of the present invention, the nut is fitted at the same time as the thread is formed on the end of the PO steel material, so the process of fitting the nut can be omitted, and the tension applied to the PO steel material is reduced through the tension plate. When releasing the rivet, there is no need to separate the rivet head with a gas burner or chisel, unlike when a rivet head is formed on the edge of the PC#I material and the rivet head is locked to the tension plate, and the rivet can be removed. Tension release work can be done efficiently and safely.

[Brief explanation of the drawing]

Fig. 1 is a plan view of an apparatus for carrying out the method of the present invention;
The figure is a partial sectional view of Fig. 1, and Fig. 3 is a seat at the end of the 81 rc steel material. Figure 7 is a side view of the state in which the tension rule is attached.
It is a side view of a state in which a PA steel material is inserted into the hole and locked with a nut. l...PO steel material, co...nut, 3...receiving electrode, da...
Hydraulic cylinder, S... Thin electrode, 6... Hydraulic cylinder, Ri... Tension pulley), G... Holding member. Applicant Nippon Concrete Industries Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] (1) Insert a nut into the end of the po steel material that does not have a thread,
The nut and the end face of the PA steel material are connected to the pushing electrode, the PO steel material is held between the receiving electrode placed at a distance between the nut and the PO steel material, and current is applied between the receiving electrode and the pushing electrode. Heat and push the electrode toward the receiving electrode, expand the outer circumference of the po steel end into the thread groove on the inner surface of the nut, and insert the po steel with the nut attached.
P characterized in that the steel material is removed from the receiving electrode and the pushing electrode and the nut at the end of the PC steel material is locked to the tension plate.
O steel material locking method.