Relay joint fixing jig

Abstract

A relay joint fixing jig for connecting reinforcing bars to concrete structures is provided. [Solution] The system comprises first members 8A-8C that are screwed into a formwork floor 10, a second member 2 that fits into the first member, and a sacrificial nut 4 that secures the second member to the first member, with a relay joint 6 screwed onto the outer periphery of the second member. The relay joint can be held stably and reliably against the formwork floor surface, preventing the relay joint from tilting or coming loose during the concrete product manufacturing process.

Description

[Technical Field]

[0001] The present invention relates to a relay joint fixing jig. [Background technology]

[0002] Traditionally, in the construction industry, relay joints (rebar joints) have been widely used to connect rebar to concrete structures. A relay joint is a joint in which at least the ends of the rebar are threaded and then screwed into a threaded coupler, firmly connecting two rebars in the axial direction. The use of relay joints allows rebars to be joined without welding, which is expected to improve workability and stabilize quality. Summary of the Invention [Problem to be solved by the invention]

[0003] When relay joints are embedded in concrete products in advance, it is necessary to prevent the relay joints from tilting or shifting from their designated positions when the concrete is poured. In particular, it is not easy to accurately hold the relay joints on the floor of the formwork, and if the pressure of the concrete during pouring causes the relay joints to change position, this could have a negative impact on the accuracy of the rebar connections and construction accuracy in the finished concrete product.

[0004] The present invention aims to solve at least one of the problems of the above-mentioned conventional technology, and specifically aims to provide a jig that can stably and reliably hold a relay joint against the formwork floor surface and prevent the relay joint from tilting or coming loose during the manufacturing process of concrete products. [Means for solving the problem]

[0005] The first relay joint fixing jig of the present invention is a relay joint fixing jig comprising a first member that is screwed into the formwork floor, a second member that is fitted into the first member, and a sacrificial nut that fixes the second member to the first member, and is characterized in that a relay joint is screwed onto the outer periphery of the second member. [Effects of the Invention]

[0006] According to the present invention, at least one of the problems of the prior art can be solved. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a partial cross-sectional view showing a state in which a relay joint is fixed to a form floor surface using a jig according to an embodiment of the present invention. [Figure 2] FIG. 2 is an exploded view of FIG. 1. [Figure 3] FIG. 10 is a diagram showing the state when the concrete product is demolded. [Figure 4] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present invention will be described below with reference to Figures 1 to 4. Figure 1 is a cross-sectional view showing a relay joint fixed to the floor of a formwork using a jig of the present invention, Figure 2 is a view showing the disassembled state, Figure 3 is a view showing the state when the concrete product is being demolded, and Figure 4 is a view showing the main components.

[0009] As shown in Figures 1, 2, and 4, the relay joint fixing jig (hereinafter simply referred to as the "jig") of the present invention is composed of a first member 8 that is screwed into a formwork floor 10, a second member 2 that is fitted into this first member 8, and a sacrificial nut 4 that fixes the second member 2 to the first member 8. A relay joint 6 is screwed onto the outer periphery of the second member 2, and a rebar 12 is previously screwed into this relay joint 6. The relay joint 6 has a through hole 6A formed therein with a female thread that corresponds to the male thread of the threaded rebar 12, and is configured to allow the rebar 12 to be connected in the axial direction.

[0010] The first member 8 is a rod-shaped body with a first threaded portion 8A formed on its outer periphery and a protrusion 8B provided in the middle. The protrusion 8B fits into the engagement groove 2A of the second member 2 to prevent the second member 2 from rotating. In addition, a second threaded portion 8C is formed at the bottom end of the first member 8 to be screwed into a threaded hole 10A in the formwork floor 10.

[0011] The second member 2 is formed in a cylindrical shape and has a through hole 2B therein through which the first member 8 passes. In this embodiment, no female thread is formed on the inner wall of the through hole 2B, and the hole diameter is formed to allow the first screw portion 8A to pass through without resistance. Note that a female thread can also be formed on the inner wall of the second member 2 for the purpose of later extracting the second member 2, but even in this case, it is necessary to adjust the hole diameter so that it does not thread into the first screw portion 8A.

[0012] An engagement groove 2A is provided at the lower end of the second member 2, which fits into a protrusion 8B on the first member 8, thereby positioning the members relative to each other and preventing rotation. The sacrificial nut 4 is made of a material strong enough to be broken when the concrete product is pulled up. Specifically, it is made of resin, wood, or paper, and synthetic resin is preferable. The sacrificial nut 4 is threaded into a first threaded portion 8A that protrudes above the first member 8, and serves to press and fix the second member 2 to the first member 8.

[0013] Next, we will explain how to use the jig of this invention. Generally, precast concrete structures (concrete products) are formed by pouring concrete into a bottomed, container-like formwork that opens upward and then curing and hardening it. The hardened concrete structure is heavy and fragile immediately after hardening, so it cannot be handled by hand. To prevent chipping, it is removed from the formwork by attaching a lifting device to a designated lifting point and lifting it upward.

[0014] Forms are often installed on flat ground to ensure stability during pouring, making it virtually impossible for workers to crawl under the form floor 10 to perform their work. For this reason, the relay joints 6 for connecting the rebars 12 must be held precisely in place by working from above the form floor 10 (the bottom of the form) before concrete is poured. In the past, the pressure of pouring concrete could cause the relay joints 6 to tilt or shift, or in the worst case, come off, potentially compromising the construction accuracy of the finished product and the accuracy of the rebar connections.

[0015] In contrast, the jig of the present invention can be stably fixed simply by screwing the first member 8 into the formwork floor 10, and the second member 2 and sacrificial nut 4 can hold the relay joint 6 in the correct position. The builder does not need to get under the floor; assembly and fixing can be completed simply by operating from above the formwork floor 10. This prevents the relay joint 6 from tilting or coming loose during concrete pouring, and ensures that the reinforcing bar 12 is held in the specified position.

[0016] 3 is a diagram showing the state when a concrete product 20 (precast concrete structure) is demolded. After the concrete product 20 is poured into a formwork and allowed to harden, the product is lifted upward (in the direction of the arrow) to remove it from the formwork, and the sacrificial nut 4 breaks. This separates the second member 2 and relay joint 6 from the first member 8, and the relay joint 6 remains embedded in the concrete product 20 together with the reinforcing bar 12.

[0017] The first member 8 remains on the form floor 10 side and can be easily removed from the form floor 10. Furthermore, when the second member 2 is removed, the broken sacrificial nut 4 is naturally ejected from the through hole 6A of the relay joint. This prevents residue from remaining inside the relay joint 6 and prevents the connectivity of the rebar 12 from being impaired.

[0018] As explained above, the jig of the present invention is composed of simple components, namely, the first member 8, the second member 2, and the sacrificial nut 4, which enable the relay joint 6 to be stably held to the form floor 10. In particular, the fact that assembly and fixing can be completed simply by operating from above, without the need for workers to crawl under the form floor 10, greatly improves the safety and efficiency of work at precast concrete structure manufacturing sites. Furthermore, by intentionally breaking the sacrificial nut 4 during demolding, the form and concrete product 20 can be easily separated, ensuring that the relay joint 6 and reinforcing bar 12 remain inside the product.

[0019] The present invention is not limited to the above-described embodiment, and various modifications are possible.

[0020] For example, although the first member 8 is made of iron, stainless steel or a high-strength resin material may also be used as long as the required strength is satisfied. Furthermore, the shapes and dimensions of the protrusion 8B, first screw portion 8A, and second screw portion 8C of the first member 8 may also be changed as desired as long as the engagement relationship with the second member 2 can be maintained.

[0021] The second member 2 is not limited to a cylindrical shape either, and may be made into a hexagonal or polygonal prism shape, which may make it easier to hold using a tool during installation. The position and shape of the engagement groove 2A may also be changed as appropriate, as long as it can reliably engage with the protrusion 8B.

[0022] The sacrificial nut 4 is not limited to being made of rigid resin, but may be made of thin metal material to ensure breakability. The fracture method of the sacrificial nut can also be configured according to the usage environment, such as shear fracture or split fracture.

[0023] Furthermore, while the above embodiment shows an example of holding the relay joint 6, the present invention can be applied to other applications besides rebar couplers. For example, it can be used to accurately hold inserts and various anchors on the formwork floor. In this case, too, the sacrificial nut 4 breaks during demolding, making it easy to separate the formwork floor 10 from the concrete product 20. [Explanation of symbols]

[0024] 2 Second member 4 Sacrificial Nuts 6 Relay Joint 8 First member 10 Formwork floor 12 Reinforced concrete 20 Concrete products

Claims

1. A first member that is screwed into the formwork floor, a second member that is fitted to the first member, and a sacrificial nut that fixes the second member to the first member; A relay joint fixing jig, characterized in that a relay joint is screwed onto the outer periphery of the second member.

2. 2. The relay joint fixing jig according to claim 1, wherein the first member has a protrusion at a midpoint thereof, and the protrusion is fitted into an engagement groove of the second member, thereby preventing rotation of the second member.

3. 3. The relay joint fixing jig according to claim 1, wherein the sacrificial nut is made of resin and is configured to break when the concrete product is demolded, thereby separating the relay joint and the second member from the first member.

4. The relay joint fixing jig according to claim 3 , wherein a threaded portion for screwing into a form floor is formed at a lower end of the first member.

5. 5. The relay joint fixing jig according to claim 4, wherein a reinforcing bar is screwed into the relay joint in advance, and the reinforcing bar is erected from the form floor.

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