Method for burying reinforcement bar into wooden member

Abstract

To provide a method for securely and firmly joining a wooden member to a member to be joined in a short time and a method for firmly reinforcing a wooden member in a short time using both of a dielectric heating method and a heat conduction heating method.SOLUTION: A method for burying a reinforcement bar into a wooden member according to the present invention includes: a hole boring step of boring a reinforcement bar burying hole into a wooden member; a reinforcement bar insertion step of inserting a reinforcement bar made of a conductor into the reinforcement bar burying hole; a terminal part formation step of forming a terminal part exposed to the outside while being communicating with the inserted reinforcement bar; an adhesive filling step of filling an epoxy adhesive into the reinforcement bar burying hole; an application step of connecting the terminal part to a power source and applying high frequency power in such a manner that the reinforcement bar is utilized as a first electrode and a second electrode facing the first electrode is arranged; and an adhesive curing step of heating the adhesive in the wooden member by the application to cure the adhesive.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for embedding reinforcing bars using an adhesive filled within a wooden member, for example, when a wooden member (such as a wooden pillar) is used as a joining member to be joined to a joined member such as a wooden beam, a concrete foundation, or a steel material via reinforcing bars, or when reinforcing the wooden member itself. [Background technology]

[0002] In the past, it was common to embed reinforcing bars in wooden members via adhesive, and to accelerate the hardening of the adhesive, the adhesive inside the wooden members was heated. Methods for heating the adhesive include covering the outside of the wooden members with a blanket or the like and heating the adhesive inside the wooden members, i.e., heat conduction heating, but this method raises the temperature slowly and makes it difficult to effectively heat the adhesive inside the wooden members.

[0003] It is also known that at manufacturing sites for wooden components such as laminated timber, when wooden laminas are assembled and glued together, dielectric heating is performed by applying high-frequency power to accelerate the hardening of resorcinol-based adhesives. However, dielectric heating has the characteristic that materials with higher dielectric loss coefficients are heated in order. In the case of adhesives with a lower dielectric loss coefficient than the wooden components, such as epoxy-based adhesives used to embed reinforcing bars, the wooden components heat up before the adhesive, causing the internal temperature to become high. It is known that this overheating can cause changes in the color of the wooden components themselves and deterioration in their strength.

[0004] The inventors therefore discovered that the problems with the thermal conduction heating method and the dielectric heating method described above can be resolved by using both of these heating methods in a hybrid manner, and developed the reinforcing bar embedding method shown in Patent Document 1 below. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7036330 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the reinforcing bar embedding method of Patent Document 1, the wooden member is placed between a pair of electrodes and high-frequency power is applied to heat the wooden member itself, and the adhesive is heated by thermal conduction from the heated wooden member, so that the epoxy adhesive inside the wooden member can be heated effectively in a short time. This allows the hardening of the epoxy adhesive to be appropriately promoted, and the reinforcing bar can be firmly embedded in the wooden member.

[0007] However, in the reinforcing bar embedding method of Patent Document 1, if the wooden component has a large cross-section, the distance between the electrodes becomes large, making it impossible to heat the wooden component effectively and therefore potentially preventing heat conduction to the adhesive.

[0008] In particular, in recent years, wooden components are often used for the columns and beams of mid- and high-rise buildings, and the cross-sections of wooden components are becoming larger. There is a strong demand for a method that can heat adhesives effectively and quickly when embedding reinforcing bars in large cross-section wooden components. [Means for solving the problem]

[0009] The reinforcing bar embedding method of the present invention has been developed to effectively solve the problems associated with the above-mentioned conventional reinforcing bar embedding methods, and provides a reinforcing bar embedding method that can appropriately heat the adhesive filled inside wooden components, even if the components have a large cross-section.

[0010] In summary, the method of embedding reinforcing bars in wooden components according to the present invention (hereinafter simply referred to as the "reinforcing bar embedding method") is a method of embedding reinforcing bars in wooden components, and is characterized by comprising the following steps.

[0011] That is, the method includes a hole drilling step of drilling a hole for embedding a reinforcing bar in a wooden member, a reinforcing bar inserting step of inserting a reinforcing bar made of a conductor into the hole for embedding the reinforcing bar, a terminal forming step of forming a terminal part exposed to the outside while communicating with the inserted reinforcing bar, an adhesive filling step of filling the hole for embedding the reinforcing bar with an epoxy adhesive, a high-frequency power application step of connecting the terminal part to a power source to use the reinforcing bar as a first electrode and disposing a second electrode facing the first electrode to apply high-frequency power, and an adhesive hardening step of heating the adhesive in the wooden member by applying the high-frequency power to harden the adhesive. Thus, the reinforcing bar embedded in the wooden member can be used as an electrode, the wooden member can be effectively heated even if it has a large cross section, and the adhesive in the wooden member can be appropriately hardened.

[0012] Preferably, the high frequency power is applied simultaneously to a plurality of the reinforcing bars, each of which is used as a first electrode, so that dielectric heating can be performed simultaneously over a wide area.

[0013] Furthermore, by disposing the second electrode on the periphery of the wooden member, the facing state with respect to the first electrode can be adjusted, so that the portion of the wooden member sandwiched between the second electrode and the first electrode can be appropriately heated, and the adhesive around the reinforcing bar that is ultimately used as the first electrode can be effectively heated.More preferably, by disposing a plurality of the second electrodes and applying the high frequency power to each of the second electrodes simultaneously, the wooden member can be reliably heated and the adhesive therein can be heated.

[0014] Furthermore, by using the reinforcing bar other than the reinforcing bar used as the first electrode as the second electrode, the portion of the wooden member between the reinforcing bar used as the first electrode and the reinforcing bar used as the second electrode can be effectively dielectrically heated, and the adhesive in contact with that portion of the wooden member can be heated by thermal conduction to promote hardening. Effect of the Invention

[0015] According to the reinforcing bar embedding method of the present invention, reinforcing bars can be embedded reliably and firmly within a short period of time even if the wooden component has a large cross section. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a perspective view showing a hole drilling step in the reinforcing bar embedding method according to the present invention. [Diagram 2] FIG. 2 is a perspective view showing a reinforcing bar inserting step and an adhesive filling step in the reinforcing bar embedding method according to the present invention. [Diagram 3] FIG. 2 is a perspective view showing a terminal portion forming step in the reinforcing bar embedding method according to the present invention. [Figure 4] FIG. 2 is a perspective view showing an application step and an adhesive hardening step in the reinforcing bar embedding method according to the present invention. [Diagram 5] FIG. 11 is a perspective view showing another example of a terminal portion forming step. [Figure 6] FIG. 11 is a perspective view showing another example of the application step and the adhesive curing step. [Figure 7] 13 is a perspective view showing an application step and an adhesive curing step in which both of a pair of electrodes are constructed using reinforcing bars. FIG. [Figure 8] FIG. 13 is a perspective view showing an example of power supply to a plurality of reinforcing bars. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] An optimal embodiment of a reinforcing bar embedding method according to the present invention will be described with reference to Figs.

[0018] <Basic configuration> The reinforcing bar embedding method according to the present invention is a method for embedding reinforcing bars 1 via adhesive in a wooden member 10 such as a wooden building material, as shown in Figs. 1 to 8. The embedded reinforcing bars 1 function as a joining member when the wooden member 10 is used as a joining member to join members to be joined, such as wooden beams, concrete foundations, and steel materials, via reinforcing bars, and of course reinforce the wooden member itself. In addition to solid wooden members, structural laminated lumber, LVL (Laminated Veneer Lumber), and CLT (Cross Laminated Timber) can be used as the wooden member 10.

[0019] The reinforcing bar embedding method according to the present invention has the following steps as its basic configuration.

[0020] First, as shown in Figures 1 to 3, the method includes a hole drilling process for drilling a hole 12 for embedding reinforcing bar in a wooden member 10, a reinforcing bar insertion process for inserting a reinforcing bar 1 into the hole 12 for embedding reinforcing bar, a terminal portion forming process for forming a terminal portion 20 that is connected to the inserted reinforcing bar and exposed to the outside, and an adhesive filling process for filling the hole 12 for embedding reinforcing bar with adhesive 2 and covering the outer surface of the reinforcing bar 1 with the adhesive 2.

[0021] Next, as shown in FIG. 4, the method includes an application process in which the terminal portion 20 of the reinforcing bar 1 is connected to a power source (AC power source) 30 to use the reinforcing bar 1 as a first electrode 31 and a second electrode 32 is disposed opposite the first electrode 31 to apply high-frequency power, and an adhesive hardening process in which the adhesive 2 in the wooden member 10 is heated by the application, thereby hardening the adhesive 2.

[0022] As the reinforcing bars 1, metal rods such as deformed reinforcing bars, fully threaded bolts, and round steel bars, as well as reinforcing bars made of conductors, can be used, and they can be used appropriately depending on the required strength and the load-bearing capacity of the area of ​​use. The number of reinforcing bars to be buried can be adjusted appropriately depending on the joints and reinforcement areas.

[0023] An epoxy adhesive is used as the adhesive 2. After curing, the epoxy adhesive forms a high-strength adhesive layer, which reliably embeds the reinforcing bars 1. It is known that the dielectric loss coefficient of epoxy adhesives at high frequencies (short wave: 3 to 30 MHz, very short wave: 30 to 300 MHz) is generally lower than the dielectric loss coefficient of wooden members 10 dried for use as structural materials. Therefore, in dielectric heating, the wooden members 10 are heated preferentially over the adhesive 2, and the adhesive 2 is heated by heat conduction from the heated wooden members 10.

[0024] Preferably, a two-part curing epoxy adhesive consisting of a liquid base agent and a liquid curing agent is used as the adhesive 2, so that the timing of the start of curing can be adjusted and a high-hardness adhesive layer (reinforcement-bar embedding layer) can be formed. The viscosity of the adhesive 2 can be appropriately adjusted, taking into consideration both the ability to spread the adhesive 2 over the entire outer surface of the reinforcing bar 1 and the ability to retain the adhesive on the outer surface.

[0025] Next, each step of the reinforcing bar embedding method according to the present invention will be described in detail.

[0026] <Hole drilling process> As shown in Fig. 1, reinforcing bar embedding holes 12 for inserting the reinforcing bars 1 are drilled in advance at the component manufacturing factory or construction site in a wooden component 10 in which the reinforcing bars 1 are to be embedded. The reinforcing bar embedding holes 12 open at the joint surface 11. The number of reinforcing bars 1 is appropriately selected depending on the required strength, etc., and the number of reinforcing bar embedding holes 12 corresponding to the number of reinforcing bars 1 are drilled. Note that 13 in the figure denotes adhesive filling holes that communicate with each reinforcing bar embedding hole 12.

[0027] The hole diameter of the hole 12 for embedding the reinforcing bar is set to 1.2 to 1.5 times the diameter (maximum diameter) of the reinforcing bar 1 so that it can absorb any misalignment or inclination of the reinforcing bar 1 and also so that a sufficient amount of adhesive 2 can cover the outer surface, especially the outer peripheral surface, of the reinforcing bar 1.

[0028] <Reinforcing bar insertion process, terminal formation process> Next, as shown in FIG. 2, the reinforcing bars 1 are inserted into each of the reinforcing bar embedding holes 12 described above.

[0029] As shown in Fig. 3, the inserted reinforcing bar 1 exposes one end 1a and the other end 1b to form a terminal part 20. In other words, when inserting the reinforcing bar 1 into the hole 12 for embedding the reinforcing bar, one end 1a and the other end 1b of the reinforcing bar 1 are caused to protrude from the hole 12 for embedding the reinforcing bar, and the protruding ends are used as the terminal part 20. Note that in the present invention, it is optional to cause only one end 1a or the other end 1b of the reinforcing bar 1 to protrude and be used as the terminal part 20 depending on the implementation.

[0030] Preferably, a screw thread 21 is formed at the end of the reinforcing bar 1 used as the terminal portion 20, and a nut 22 is screwed onto the screw thread 21 as described below, thereby firmly fixing the reinforcing bar 1 and facilitating connection to an electric wire, etc., in the application process described below, making it easy to use as the terminal portion 20.

[0031] Furthermore, when the protruding end of the reinforcing bar 1 is used as the terminal portion 20 as described above, the protruding end can also be used for joining to other members.

[0032] In the present invention, in addition to using the protruding end of the reinforcing bar 1 as the terminal portion 20 as described above, as shown in Figure 5, instead of having the end of the reinforcing bar 1 protrude from the reinforcing bar embedding hole 12, the reinforcing bar 1 is made into a tubular structure, a screw groove 23 is engraved on its inner surface, and a bolt 24 is screwed into the screw groove 23, so that the head of the bolt 24 can be used as the terminal portion 20.

[0033] <Adhesive filling process> As described above, after inserting the reinforcing bars 1 into each reinforcing bar embedding hole 12, the prepared adhesive 2 is injected through the adhesive filling hole 13, and as shown in the enlarged view in Fig. 4, the adhesive 2 is spread evenly between the outer peripheral surface 1c of the reinforcing bar 1 and the inner peripheral surface 12a of the reinforcing bar embedding hole 12, and the outer surface of the reinforcing bar 1 is filled so as to be covered with the adhesive 2. By covering the outer surface of the reinforcing bar 1 with the adhesive 2 in this way, the reinforcing bar 1 is securely embedded.

[0034] In the present invention, it is not excluded to preheat the adhesive 2 before filling it by using a known heat conduction heating method such as a hot water bath.

[0035] <Application process, adhesive curing process> As described above, after the adhesive 2 is filled around the reinforcing bar 1 in the wooden member 10, the terminal portion 20 of the reinforcing bar 1 used as an electrode is connected to an AC power source 30 via an electric wire or the like, and the reinforcing bar 1 is used as a first electrode 31, as shown in Fig. 4. In addition, a second electrode 32, which is also connected to the AC power source 30, is disposed opposite the first electrode 31.

[0036] In this manner, by supplying power from AC power supply 30 with first electrode 31 and second electrode 32 facing each other, high-frequency power is applied to the portion sandwiched between first electrode 31 and second electrode 32, which heats the portion, and the heat is then conducted to heat adhesive 2 and promote the hardening of adhesive 2.

[0037] In the present invention, the number of reinforcing bars 1 used as the first electrode 31 may be one or more, and can be appropriately selected depending on the buried position of the reinforcing bars 1, etc. However, if high frequency power is applied to multiple reinforcing bars 1 simultaneously and each of the reinforcing bars 1 is used as a first electrode 31, it is possible to simultaneously perform dielectric heating over a wide area. When high frequency power is applied to multiple reinforcing bars 1 simultaneously, for example, as shown in Figure 8, if this is done via a metal plate 25 such as a thin copper plate, it becomes easy to adjust the height and change the shape, despite the simple structure, and power can be reliably supplied to multiple reinforcing bars 1.

[0038] 4 and 6, the second electrode 32 can be disposed on the periphery of the wooden member 10. Therefore, the facing state of the second electrode 32 with respect to the first electrode 31 can be freely adjusted, so that the portion of the wooden member sandwiched between the second electrode 32 and the first electrode 31 can be appropriately heated, and ultimately, the adhesive around the reinforcing bar 1 used as the first electrode 31 can be effectively heated.

[0039] Although not specifically shown, a plurality of second electrodes 32 can be arranged to face the first electrode 31. For example, the second electrodes 32 can be arranged at both the positions of the second electrodes 32 shown in Fig. 4 and the positions of the second electrodes 32 shown in Fig. 6, so that a plurality of second electrodes 32 can be arranged to face the first electrode 31. In this way, by arranging a plurality of second electrodes 32 and simultaneously applying high-frequency power to each of the second electrodes 32, the wooden member 1 can be reliably heated, and the adhesive 2 therein can be heated.

[0040] In the present invention, a reinforcing bar 1 other than the reinforcing bar 1 used as the first electrode 31 can be used as the second electrode 32. By configuring in this way, the part of the wooden member between the reinforcing bar 1 used as the first electrode 31 and the reinforcing bar 1 used as the second electrode 32 can be effectively dielectrically heated, and the adhesive 2 in contact with the part of the wooden member can be heated by thermal conduction to promote hardening.

[0041] The first electrode 31 and the second electrode 32 can be used as both power supply electrodes and earth electrodes. Therefore, by configuring the first electrode 31 and the second electrode 32 so that the polarity can be switched, and by switching between the power supply electrodes and the earth electrodes and applying voltage multiple times, the adhesive 2 can be heated evenly. In addition, the adhesive 2 can be heated evenly by changing the positions and opposing states of the first electrode 31 and the second electrode 32 and applying voltage multiple times.

[0042] The applied high-frequency power is adjusted appropriately depending on the heating range. When the heating range is small, for example, a small output (0.1 to 5 kW) can be used. The high-frequency oscillator can be a known electron tube type or semiconductor type device. In particular, the use of a small semiconductor type oscillator is very convenient for use at construction sites or at high altitudes. In the present invention, the high frequency refers to electromagnetic waves with known frequencies (short wave: 3 to 30 MHz, ultrashort wave: 30 to 300 MHz) and wavelengths (short wave: 100 to 10 m, ultrashort wave: 10 to 1 m) that are conventionally used in dielectric heating.

[0043] The high frequency power and its application time are adjusted, and application is performed while monitoring the internal temperature of the wooden member 10 using a known sensing means such as a temperature sensor so that the temperature does not exceed 100° C. and is kept high. This is to prevent deterioration of the wooden member 10 during the process of heating the wooden member 10 by dielectric heating and then heating the adhesive 2 by thermal conduction.

[0044] As described above, the adhesive 2 is heated by keeping the internal temperature of the wooden member 10 at a temperature not exceeding 100°C. Preferably, the adhesive 2 is heated to a temperature of 50 to 90°C in order to promote hardening of the adhesive 2. Note that in the present invention, in the application step and adhesive hardening step, it is only necessary to heat the adhesive 2 present inside the wooden member 10 and promote hardening, and pressure bonding as in laminar bonding is not required.

[0045] As described above, according to the reinforcing bar embedding method of the present invention, by using a hybrid of dielectric heating and thermal conduction heating, the wooden member 10 can be reliably and firmly joined to the joined member in a short period of time, and the wooden member 10 can be reliably and strongly reinforced in a short period of time.

[0046] Furthermore, even if the wooden component 10 has a large cross section, the adhesive 2 inside the wooden component 10 can be heated. Therefore, the reinforcing bars 1 can be embedded securely and firmly within the wooden component 10 in a short time, which contributes to reinforcing the wooden component 10 itself and joining it to other components.

[0047] In the above embodiment, both ends of the wooden member 10 are used as the joint surface 11, but the present invention naturally includes a case where only one end of the wooden member 10 is used as the joint surface 11. In addition, in the above embodiment, a case where the reinforcing bars 1 are embedded along the longitudinal direction of the wooden member 10 is described, but the present invention does not exclude a case where the reinforcing bars 1 are embedded along the lateral direction of the wooden member 10 (the direction perpendicular to the longitudinal direction).

[0048] In the reinforcing bar embedding method according to the present invention, the adhesive filling step and the terminal portion forming step may be performed in any order, or may be performed simultaneously. [Explanation of symbols]

[0049] 1...reinforcing bar, 1a...one end, 1b...other end, 1c...outer surface, 2...adhesive, 10...wooden member (joined member), 11...joining surface, 12...hole for burying reinforcing bar, 12a...inner surface, 13...hole for filling with adhesive, 20...terminal portion, 21...thread, 22...nut, 23...thread groove, 24...bolt, 25...metal plate, 30...AC power source, 31...first electrode, 32...second electrode.

Claims

1. a terminal forming step of forming a terminal portion that communicates with the inserted reinforcing bar and is exposed to the outside; an adhesive filling step of filling the hole for embedding reinforcing bar with an epoxy-based adhesive; an application step of connecting the terminal portion to a power source, using the reinforcing bar as a first electrode and disposing a second electrode opposite the first electrode, and applying high-frequency power; and an adhesive hardening step of heating the adhesive in the wooden member by applying the power, thereby hardening the adhesive.

2. 2. The method for embedding reinforcing bars in wooden members according to claim 1, wherein the high frequency power is applied to a plurality of reinforcing bars simultaneously, and each of the reinforcing bars is used as a first electrode.

3. 2. The method for embedding reinforcing bars in a wooden member according to claim 1, wherein the second electrode is disposed on a periphery of the wooden member.

4. 4. The method for embedding reinforcing bars in wooden members according to claim 3, wherein a plurality of said second electrodes are provided, and said high frequency power is applied to each of said second electrodes simultaneously.

5. 2. The method for embedding reinforcing bars in wooden members according to claim 1, wherein a reinforcing bar other than the reinforcing bar used as the first electrode is used as the second electrode.

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