JP6689028B2 - Reinforcing bar joint method - Google Patents

Description

  The present invention relates to a structure for connecting reinforcing bars in an extension direction, and a reinforcing bar and a sleeve used in the reinforcing bar joint.

  Conventionally, as a reinforcing bar joint in which a sleeve is interposed, there is one in which a male screw is engraved on the reinforcing bar (see Patent Document 1). However, when the male screw is directly engraved on the tip of the reinforcing bar, it is expected that the effective diameter of the reinforcing bar at the tip portion becomes small, which may cause the strength of the reinforcing bar to decrease. Therefore, in order to maintain the strength of the reinforcing bar, assuming that a male screw is engraved, use a reinforcing bar with a diameter larger than the original diameter of the reinforcing bar. However, it is not economically preferable.

  Therefore, recently, there has been proposed a technique in which a diametrically expanded portion is formed at the tip of a reinforcing bar and a male screw is engraved on the diametrically expanded portion (see Patent Document 2). This technology engraves a male thread with a thread count of 6 to 9 on the expanded diameter portion, and the root diameter of the engraved male thread is 1.05 to 1.50 times the rebar diameter. It was.

JP, 2011-190589, A Utility model registration No. 3160121

  However, in the joint disclosed in the above-mentioned Patent Document 2, the thread (pitch number) of the male screw engraved on the reinforcing bar is in the range of 6 to 9, so that the sleeve is maximally screwed. Even so, the number was nine. The strength of the joint portion depends on the total area of the threads, but when the male threads are screwed together with the threads (number of pitches) of less than 9, the strength is further increased. It will be lowered. Therefore, even if the male screw is simply screwed into the sleeve, the strength of the reinforcing bar and the strength of the connecting portion cannot be secured.

  Furthermore, in the above-mentioned prior art, it is not clear whether or not the axes of the reinforcing bars to be connected are in agreement, and it is necessary to correct the deviation of the axes when screwing into the sleeve. The joint operation at the work site was more complicated than expected.

  The present invention has been made in view of the above points, and its purpose is to provide a reinforcing bar joint that allows easy joint work while maintaining the strength of the reinforcing bar and the strength of the connecting portion, and therefore To provide a reinforcing bar and a sleeve.

  Therefore, the present invention according to the reinforcing bar joint is a reinforcing bar joint that connects both reinforcing bars by interposing sleeves at both ends of the reinforcing bars to be connected, and both the reinforcing bars are at the tip with respect to the nominal cross-sectional area of the reinforcing bar. It is provided with a diameter-expanded portion sufficiently expanded to have a cross-sectional area exceeding 1.5 times, and the effective cross-sectional area is 1.5 times or more the nominal cross-sectional area of the reinforcing bar, and / or per pitch. A male screw having a screw area of 20% or more of the nominal cross-sectional area of the reinforcing bar is engraved on the enlarged diameter portion, and the sleeve is formed in a tubular shape, and the inner diameter portion thereof has the male screw. Female threads to be screwed are engraved, and the male threads engraved on the expanded diameter portions of the rebars from both ends have a length such that 10 or more pitches can be screwed therein.

  According to the above configuration, firstly, the expanded diameter portion has a cross-sectional area exceeding 1.5 times the nominal cross-sectional area of the reinforcing bar, and the male thread when the expanded diameter portion is engraved with a male screw. Since the effective cross-sectional area of the screw is 1.5 times or more, the cross-sectional area in the entire area of the portion (screw portion) that acts on the joint is larger than the diameter of the reinforcing bar, and The strength can be sufficiently retained. Secondly, since the male screw of the expanded diameter portion and the female screw of the sleeve are screwed with each other at 10 pitches or more, the load acting on the joint can be distributed to the threads of 10 pitches or more. At this time, if the screw area per pitch is 20% or more of the nominal cross-sectional area of the reinforcing bar, the total area of 10 pitches is doubled, and the load acting on the joint can be endured.

  Here, the "nominal cross-sectional area" of a reinforcing bar means the cross-sectional area that is shown for a reinforcing bar that is not a uniform round bar such as a deformed reinforcing bar. It is larger than the cross-sectional area. Further, the "effective cross-sectional area" is a cross-sectional area calculated in consideration of the ridges and valleys of the screw formed by engraving the male screw, and is calculated based on the effective diameter of the screw part. Is.

  In the invention of the above configuration, the sleeve is made of carbon steel, and the female screw engraved on the sleeve and the male screw engraved on the expanded diameter portion are both metric screws. can do.

  By constructing the sleeve from carbon steel, the sleeve can be manufactured at low cost, the tensile strength, the compressive strength, the shear strength, etc. can be easily calculated, and the sleeve having the desired strength can be obtained. Further, since the male screw and the female screw are engraved with the metric screw, it is possible to perform processing by a general-purpose processing machine. The metric screw in this case can be configured with a peak diameter and a valley diameter as specified in JIS, and the effective diameter can also be formed in a state in accordance with the standard. Since the metric screw is determined by the outer diameter of the expanded diameter portion (thread diameter of the thread), when the cross-sectional area of the expanded diameter portion is determined as described above, the outer diameter of the expanded diameter portion is also Since it is inevitably determined, if the nominal cross-sectional area of the reinforcing bar is determined, the male screw to be engraved is also determined. Further, since the screw area per pitch is specified according to the standard, the strength of the screw portion (screwed portion) by screwing with 10 pitches or more can also be assumed.

  Further, in the invention of each of the above configurations, at least one of the sleeves may be crimped by a lock nut screwed to the male screw of the enlarged diameter portion.

  In the case of such a configuration, it is possible to prevent the sleeve from rotating and loosening the screwed state by crimping with the lock nut. "Crimping" does not mean that both members are fixed, but means that they are in contact with each other while being strongly pressed. Since both of them are screwed into the same male screw, the pushing force can be given by the screwing of the lock nut.

  In the case of the above configuration, the lock nut is further provided with a female screw that is screwed into the male screw of the enlarged diameter portion at at least 4 pitches, and the enlarged diameter portion is screwed with the sleeve and A male screw for screwing the lock nut may be continuously engraved.

  According to the above configuration, since the lock nut is screwed with the male screw of the enlarged diameter portion at 4 pitches or more, sufficient strength can be provided against the load acting on the lock nut. In particular, the lock nut, which is abutted (compressed) on the sleeve, is basically an individual member, so that it can be arranged in the expanded diameter portion of the reinforcing bar independently of the sleeve.

  The expanded diameter portion in each invention of the above-mentioned configuration is one that is bulged by compressing in the axial direction after heating the tip end of the reinforcing bar, expanded diameter by heading processing, or expanded diameter portion at the tip end of the reinforcing bar. It can be constituted by any of the pressure-bonded members.

  When forming the expanded diameter part by any of the above, the expanded diameter part can be configured by using the rebar material as it is by hot working or cold working, and the pressure welding technique that is generally used as a reinforcing bar connecting method. The diameter-expanded portion formed of a desired material can be formed at the tip of the reinforcing bar. When the expanded diameter portion is provided at the tip of the reinforcing bar by pressure welding, a male screw may be formed in advance on the expanded diameter portion, or a male screw may be engraved after the pressure welding. Further, the pressure welding can use a conventional method for connecting the reinforcing bars, such as friction welding or gas pressure welding. It should be noted that, by performing these pressure welding and male screw processing in advance in the factory, the rebar can be connected only by the easy connecting method by screwing the sleeves on site.

  Further, the male screw of the expanded diameter portion in the above configuration may be provided with a concave portion at the center of the end surface of the expanded diameter portion, and the positioning member may be arranged in the concave portion.

  In the case of the above configuration, when the tips of the reinforcing bars to be connected are arranged in a predetermined state, the end surfaces of the expanded diameter portions formed at the tips of both reinforcing bars face each other, and the positions of the recesses of these end surfaces are aligned. As a result, the shaft centers of both the reinforcing bars can be matched. Therefore, by disposing the positioning member in the concave portion, the reinforcing bar can be arranged in a state where the concave portions of both the expanded diameter portions are aligned. Here, the positioning member may be any member that can be simultaneously engaged with the concave portions arranged opposite to each other, and may be, for example, a spherical shape or a shape in which two conical shapes are combined at the bottom surface. Further, the positioning member may have a size so as to be buried in two facing concave portions, and may have a size such that a part of each of the concave portions is engaged to form a gap on both end faces of the expanded diameter portion. You may comprise. The concave portion may be a concave portion for centering formed in lathe cutting, or may be separately formed by a punch or the like. The positioning member may be fixed to the single edge side of the expanded diameter portion of one of the reinforcing bars, but an individual member separated from the end face may be used.

  INDUSTRIAL APPLICABILITY The present invention relating to a reinforcing bar is used for the reinforcing bar joint described in any one of the above, and includes a diameter-increased portion having a cross-sectional area of more than 1.5 times the nominal cross-sectional area of the reinforcing bar and the expanded diameter part. A male screw part having an external thread of 10 pitches or more having an effective area of 1.5 times or more the nominal area of the reinforcing bar is provided on the outer peripheral portion of the diameter portion. It is a feature.

  According to the reinforcing bar having the above-mentioned configuration, the male screw is engraved on the expanded diameter portion having a cross-sectional area sufficiently larger than the nominal cross-sectional area of the reinforcing bar, so that the influence of strength reduction due to the formation of the male screw can be eliminated. You can Further, since the male screw engraved on the enlarged diameter portion has a pitch of 10 or more, it can be screwed with the sleeve at a pitch of 10 or more. Further, when the lock nut is used, the male screw has a pitch number of 10 pitches plus the range in which the lock nut can be screwed. Even with such a relatively long diameter-expanded portion and male screw portion, the effective cross-sectional area of the male screw is 1.5 times or more the nominal cross-sectional area of the reinforcing bar, so that it has sufficient strength against bending load. It will be.

  Further, the present invention relating to a reinforcing bar is a reinforcing bar used in a reinforcing bar joint having a configuration in which the positioning member is arranged, and has an expanded diameter having a cross-sectional area exceeding 1.5 times the nominal cross-sectional area of the reinforcing bar. Part, a male screw part in which an external thread of 10 pitches or more is engraved on the outer peripheral part of the expanded diameter part by cutting with a lathe, and for centering used in the lathe cutting process at the end face center of the expanded diameter part It is characterized by including the recessed part.

  According to such a configuration, when the male screw is formed by lathe cutting on the outer peripheral portion of the sufficiently expanded diameter portion, the centering concave portion that is necessarily formed is provided with the positioning member. Could be used for.

  On the other hand, the present invention relating to a sleeve is used for a reinforcing bar joint of each of the above-mentioned constitutions, and a cylindrical sleeve body having a length that allows the male screw to be screwed in from both ends by 10 pitches or more, and a sleeve body of the sleeve body. And a female screw portion engraved on the inner diameter portion.

  According to the sleeve having the above-described configuration, both ends of the two reinforcing bars to be connected can be screwed into each other from both sides by 10 pitches or more, and the ends of the two reinforcing bars can be connected sufficiently firmly. The female screw is engraved in a continuous state on the entire inner diameter portion, and since the male screw is inserted into each of 10 pitches or more, the total number of pitches of the female screw is 20 or more.

  ADVANTAGE OF THE INVENTION According to this invention which concerns on a reinforcement joint, a joint work can be easily performed, maintaining the strength of a reinforcement and the strength of a connection part. Further, according to the present invention related to the reinforcing bar, a structure that can be used for the joint is realized, and according to the present invention related to the sleeve, the structure can be interposed in the reinforcing bar.

It is explanatory drawing which shows embodiment of this invention which concerns on a reinforcement joint. It is explanatory drawing which shows the expansion part of a reinforcing bar, and the formation method of a male screw. It is explanatory drawing which shows the expansion part of a reinforcing bar, and the formation method of a male screw. It is explanatory drawing which shows the state of connection by embodiment which concerns on a reinforcement joint. It is explanatory drawing which shows the connection state of other embodiment of this invention which concerns on a reinforcement joint. It is explanatory drawing which shows the usage method of a reinforcement joint. It is explanatory drawing which shows the usage method of a reinforcement joint. It is explanatory drawing which shows the form of the reinforcing bar used for a reinforcing bar joint.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a typical embodiment of the present invention. As shown in this figure, in the reinforcing bar joint of the present embodiment, the expanded diameter portions 11 and 21 are formed at the tips of the two reinforcing bars 1 and 2 to be connected, and male threads 12 and 22 are engraved on the surface thereof. It is composed of the installed one and the sleeve 3.

  The male threads 12 and 22 engraved on the enlarged diameter portions 11 and 21 are arranged such that the effective cross-sectional areas thereof are 1.5 times or more the nominal sectional areas of the reinforcing bars 1 and 2. The cross-sectional area of is to be expanded so as to exceed 1.5 times the nominal cross-sectional area of the reinforcing bars 1 and 2 in advance. The diameter expanding process, which will be described in detail later, means bulging the tips of the reinforcing bars 1 and 2 or joining members having a large diameter by pressure welding or the like.

  Further, the engraved male screws 12 and 22 can be based on the effective cross-sectional area as well as the screw area per pitch. That is, the screw area per pitch (the area of the portion where the screw thread is formed) is set to be 20% or more of the nominal cross-sectional area of the reinforcing bars 1 and 2. In the case of such a configuration, the total screw area corresponding to 10 pitches is twice or more the nominal cross-sectional area of the reinforcing bars 1 and 2, and the load acting on the screw threads is distributed by the screw area of the double or more. By doing so, the strength can be maintained. If the male threads 12 and 22 are metric threads according to JIS, there is regularity between the effective cross-sectional area and the thread area. Therefore, the male threads 12 and 22 are provided based on either one. However, when engraving the nonstandard male screws 12 and 22, it is preferable that both conditions are satisfied.

  The sleeve 3 is formed in a tubular shape (a cylindrical shape in the figure). In order to enable the male screws 12 and 22 engraved in the enlarged diameter portions 11 and 12 to be screwed in, the female sleeve is formed in the entire inner diameter portion. A screw 31 is engraved. The outer diameter of the cylindrical shape is 1.3 times or more the root diameter of the female screw. In this way, by setting the outer diameter to be 1.3 times or more the root diameter, the cross-sectional area can be increased, and the load acting on the reinforcing bars 1 and 2 can be endured. Further, in order to screw the male screws 12 and 22 into the sleeve 3 from both sides by 10 pitches or more, the length dimension thereof is set to be equal to or more than 10 pitches of the male screws 12 and 22. For example, when the male screw is M20 which is tilted forward, 20 mm (total 40 mm) is required as a range that can be screwed in from both sides. Furthermore, since it is more than that, for example, it can be set to 60 mm. In this case, assuming that the male screws 12 and 22 are screwed in by an amount corresponding to each 12 pitches, a range of 48 mm is used. Then, the tips of the male screws 12 and 22 do not reach the center, but in that case, the vicinity of the center of the sleeve 3 becomes a hollow state. Even if such a hollow state is formed, the strength of the sleeve 3 does not decrease due to having a sufficient thickness (cross-sectional area).

  The material for forming the sleeve 3 may be the same cast steel as the reinforcing bars 1 and 2, but carbon steel can be used. Carbon steel is an alloy in which carbon is contained in iron, but various characteristics can be obtained in a carbon content range of 0.02% to 0.2%. Since carbon steel such as S45C having a carbon content of 0.45% is versatile and has stable strength, it is possible to manufacture an inexpensive sleeve 3 by using them.

  By the way, the reinforcing bar joint of the present embodiment is configured to include the lock nuts 4 and 5. The lock nuts 4 and 5 are internally threaded with female screws 41 and 51 so as to be screwed into the male threads 12 and 22 engraved on the expanded diameter portions 11 and 12 of the reinforcing bars 1 and 2. The lock nuts 4 and 5 face the both end surfaces 30a and 30b of the sleeve 3 in a state where the male screws 12 and 22 of the reinforcing bars 1 and 2 are screwed into the sleeve 3 (a state in which they are screwed in at 10 pitches or more). It is something that is advanced. By the screwing of the lock nuts 4 and 5, the lock nuts 4 and 5 are strongly brought into contact with both end surfaces 30a and 30b of the sleeve 3 and are in a crimped state. This state is shown in FIG.

  As shown in FIG. 2, when the lock nuts 4 and 5 are screwed onto the male screws 12 and 22 and they are crimped, the sleeve 3 is firmly attached to the expanded diameter portion 11 (tips of the reinforcing bars 1 and 2). It is in the state of being connected (fixed) to. That is, it is possible to prevent the screwed state of the male screw having a pitch of 10 or more from changing due to the rotation of the sleeve 3. At the same time, the pressing force also acts on the male screws 12 and 22, so that the loosening (backlash etc.) between the screws can be eliminated and the displacement amount in the pulling direction can be reduced.

  In particular, when it is used when constructing a reinforced concrete structure, the load in the compression direction on the rebar is small, and the tensile load is important. Therefore, by using the lock nuts 4 and 5 to eliminate the looseness (backlash etc.) of the screw in the pulling direction, a strong joint strength can be obtained.

  Since the lock nuts 4 and 5 are used for the above-mentioned purpose, they need not be long like the sleeve 3, and may be provided with a screwing range of about 4 pitches at most. A pitch of 4 pitches or more means a sufficient level in consideration of the collapse of the screw thread in order to maintain the crimped state, and in reality, 3.5 pitches is sufficient.

  In order to configure the joint having the above-described configuration, the reinforcing bars 1 and 2 are provided with the expanded diameter portions 11 and 12 and the male screw portions in which the male screws 12 and 22 are engraved on the outer peripheral surfaces thereof. Further, the sleeve 3 is provided with a female screw portion having a female screw 31 engraved on the inner diameter portion. In addition, below, the part in which the male screw 12 and 22 was engraved may be described as the male screw part 12 and 22, and the part in which the female screw 31 is engraved may be described as the female screw part 31.

  Here, the diameter expansion processing will be described. The diameter expansion processing includes a case where the tips of the reinforcing bars 1 and 2 are directly processed to increase the diameter and a case where large diameter members are joined. As a method of directly processing the tips of the reinforcing bars 1 and 2, for example, there is a method of pressing the tips of the reinforcing bars 1 and 2 in the axial direction to bulge a part of the reinforcing bars 1 and 2. This state is shown in FIG. Since both the reinforcing bars 1 and 2 are formed by the same processing, only one reinforcing bar 1 is shown in the figure.

  As shown in FIG. 3 (a), when the same kind of reinforcing bar material is used up to the tip, the tip 10 in the predetermined range is pressed in the axial direction so that the tip 10 swells. is there. In order to swell the reinforcing steel material, there is a method in which the heated tip is deformed by applying a strong pressing force. For example, as used in the method for manufacturing a fixed reinforcing bar developed by the inventors of the present application (see Japanese Patent Application Laid-Open No. 2008-334206), after being heated by a high frequency induction heater, it is expanded by being compressed in the axial direction. There is a way. In addition, there is a method of expanding into a predetermined diameter and a predetermined shape by cold forging, such as heading.

  FIG. 3B shows a state in which the diameter of the reinforcing bar material has been expanded as described above. As shown in this figure, the tip portion 10 of the reinforcing bar material is compressed, while the portion bulges to the periphery to form an enlarged diameter portion 11 having an enlarged outer diameter. Since the drawing is schematically drawn, the enlarged diameter portion 11 is shown as a round bar shape, but in reality, the surface may have a distorted shape.

  By cutting the surface of the expanded diameter portion 11 formed in this manner and further threading it, the expanded diameter portion 11 having the male screw 12 as shown in FIG. 3C can be provided. . Therefore, in order to provide the male screw 12 having a predetermined effective area, the enlarged diameter portion 11 before the thread cutting has a diameter larger than the screw thread diameter of the male screw 12.

  On the other hand, it is also possible to form the expanded diameter portions 11 and 21 at the tips of the reinforcing bars 1 and 2 by joining the reinforcing bars 1 and 2 made of a material different from each other by pressure welding or the like. FIG. 4 shows a state of this type of diameter expansion processing. When the enlarged diameter portion 11 is joined to the tip of the reinforcing bar 1 by pressure welding or the like, and the enlarged diameter portion 11 is first joined to form the male screw 12 on the enlarged diameter portion 11 (FIGS. 4A and 4B). (See FIG. 4) and a case where the expanded diameter portion 11 having the male screw 12 engraved therein is joined to the tip of the reinforcing bar 1 (see FIGS. 4C and 4D).

  When engraving the male screw 12 later, as shown in FIG. 4 (a), an end surface 11 b of the small diameter portion 11 a for pressure welding is formed at one end of the expanded diameter portion 11, and this end surface 11 b is attached to the reinforcing bar 1. The end face 10a of the tip 10a is brought into contact with the end face 10b for friction welding or gas pressure welding. Then, as shown in FIG. 4 (b), a part of the material becomes a burr 11 c in the pressed peripheral portion, which is in a protruding state, but since the diameter is smaller than the main body of the expanded diameter portion 11, There is no problem in engraving the male screw 12. The state in which the male screw 12 is engraved is the same as in FIG. 4 (d).

  On the other hand, when the enlarged diameter portion 11 having the male screw 12 previously engraved therein is joined by pressure contact, as shown in FIG. 4C, the enlarged diameter portion 11 having the male screw 12 engraved on its surface, A member having a small diameter portion 11a for pressure welding provided at one end thereof is provided, and the small diameter portion 11a is pressed against the reinforcing bar 1 in the same manner as described above.

  As described above, in the case of joining by pressure welding, there is no need to engrave the male screw 12 at the tip of the long reinforcing bar 1 if the enlarged diameter portion 11 having the male screw 12 is pressed at the tip of the reinforcing bar 1. Therefore, the processing is easy, but care must be taken so that the center of the expanded diameter portion 11 (male screw 12) coincides with the axial center of the reinforcing bar 1. On the other hand, when the male screw 12 is engraved after joining the expanded diameter portion 11 first, the male screw 12 can be engraved while rotating around the axis of the rebar 1, so that the axis line of the rebar 1 And the deviation from the central axis of the male screw 12 can be prevented. Since both have advantages and disadvantages, either method may be selected.

  By the way, as described above, the male threads 12 and 22 engraved on the expanded diameter portions 11 and 12 are metric threads according to the JIS standard, and the total pitch is 10 or more. In order to engrave the number of screw pitches of 10 or more, the lengths of the diameter-enlarged portions 11 and 12 are previously formed to a length that allows engraving of the number of pitches. For example, in the case of the metric screw of M20, the length of one pitch is 2 mm, so that the pitch is 20 mm and the length of the expanded diameter portions 11 and 21 is 20 mm or more in order to engrave the male screw of 10 pitch or more. And

  When engraving male threads of 10 pitches or more, lock nuts 4 and 5 to be described later cannot be screwed together. Therefore, the lengths of the expanded diameter portions 11 and 12 are set to 50 mm, and male threads are engraved in 50 pitches. can do. As described above, the cross-sectional area of the expanded diameter portions 11 and 12 and the effective cross-sectional area of the engraved male screws 12 and 22 are 1.5 times or more the nominal cross-sectional area of the reinforcing bars 1 and 2, so Even if 11 and 21 are long, they are not inferior in strength. However, if the material is used economically, the lengths of the expanded diameter portions 11 and 12 may be set to be short.

  Next, another embodiment of the joint will be described. FIG. 5 illustrates these embodiments, and the reinforcing bars 1 and 2 are shown in cross section in order to facilitate understanding of the relationship between the reinforcing bars 1 and 2 and the sleeve 3. In addition, FIG. 5A shows the representative embodiment.

  As shown in these figures, the lock nuts 4 and 5 are not essential members. As shown in FIG. 5A, in a typical embodiment, when the male screws 12 and 22 are screwed into the sleeve 3 in a relatively short range of 10 pitches or more (11 pitches are assumed in the figure), The tips have a gap C1 inside the sleeve 3. At this time, since the male screws 12 and 22 are present outside both ends of the sleeve 3, it is possible to obtain a range in which the lock nuts 4 and 5 can be screwed into the portions.

  In contrast to this, as shown in FIG. 5B, when the male screws 12 and 22 are deeply screwed in (15 pitches are assumed in the figure), even if the sleeve 3 having the same length L1 is used, The gap C2 between the tips is narrower than in the case described above, and on the other hand, there is no region on both ends of the sleeve 3 into which the lock nut is screwed. In the case where the sleeve 3 and the sleeve 3 are screwed together as described above, the tightening force by the lock nut is not applied, but a large number of male screws 12 and 22 are screwed in from both sides of the sleeve 3. It is possible to secure the integrity of both the reinforcing bars 1 and 2 and the sleeve 3. In particular, as shown in the drawing, the rebars 1 and 2 are brought close to each other so that the gap C1 is small, so that a tensile force is applied to the rebars 1 and 2, and thereby the fastening force can be increased. is there.

  Further, in FIG. 5C, since the male screws 12 and 22 are screwed in a long range of 10 pitches or more (15 pitches in the figure) from the beginning, the length L2 of the sleeve 3 is longer than the above. It is a scale. In this case, since it is assumed that the lock nut is not screwed, most of the male screws 12 and 22 are screwed into the sleeve 3. The gap C1 at this time is set to be approximately the same as in the case of the typical embodiment (FIG. 5A). Even in such a screwed state, the male screws 12 and 22 are screwed into the sleeve 3 from both sides in a wide range without using a lock nut, and the integrity of the reinforcing bars 1 and 2 and the sleeve 3 is improved. Will be secured. As described above, the tightening with the lock nut is not necessarily required, but the labor for screwing the male screws 12, 22 of the reinforcing bars 1, 22 into the sleeve 3 and the labor for screwing the lock nuts 4, 5 are required. Considering in comparison, it is preferable to use the lock nuts 4 and 5.

  Next, a method of using the joint having the above structure will be briefly described. Here, only typical ones of the embodiments will be described. FIG. 6 shows the procedure. As shown in this figure, first, lock nuts 4 and 5 are previously inserted into both the reinforcing bars 1 and 2 to be connected (see FIG. 6A). The lock nuts 4 and 5 can be inserted by screwing (reverse) the male screw portions 12 and 22. Next, the male screw portion 12 of one rebar 1 is screwed into the female screw portion 31 from one side of the sleeve 3 (see FIG. 6 (b)). The screwing at this time is to rotate the reinforcing bar 1 or the sleeve 3 10 times or more so that the pitch is 10 pitches or more. In order not to change the screwed state at this time, one lock nut 4 is screwed and brought into contact with one end surface of the sleeve 3 (see FIG. 6C).

  Then, the male screw portion 22 of the other reinforcing bar 2 is screwed into the female screw portion 31 from the opposite side of the sleeve 3 (see FIG. 6D). At this time, the sleeve 3 is not rotated but the other reinforcing bar 2 is rotated in order to keep the screwed state between the male screw portion 12 and the sleeve 3 screwed together in advance. At this time, the number of rotations is set to 10 times or more, and the screwing of 10 pitches or more is executed. After that, the other lock nut 5 is screwed and brought into contact with the other end surface of the sleeve 3 (see FIG. 6E). After the screwing of the other lock nut 5 is completed, both lock nuts 4 and 5 are sufficiently tightened to be in a crimped state.

  FIG. 7 shows another usage method. As shown in this figure, the sleeve 3 is previously inserted into the one rebar 1 together with the one lock nut 4 (see FIG. 7A). In this state, the tip surface of the reinforcing bar 1 is brought into contact with the tip surface of the other reinforcing bar 2 (see FIG. 7 (b)), and then the sleeve 3 is rotated to rotate the male screw portions 12, 22 of the reinforcing bars 1, 2. The female screw portion 31 is screwed so as to straddle (see FIG. 7C). In this case, after the screwing with the male screw portion 22 of the other reinforcing bar 2 is started, the number of rotations of the sleeve 3 becomes 10 or more so that the male screw portions 12 and 22 can be screwed with 10 pitches or more. Make adjustments.

  Even in the above-described method of use, since the lock nuts 4 and 5 are inserted into both the reinforcing bars 1 and 2 in advance, the lock nuts 4 and 5 are finally screwed sufficiently to be crimped to both end surfaces of the sleeve 3. This is done (see FIG. 7D).

  Here, in order to smoothly perform the above-described usage, there may be the following modified examples. That is, as shown in FIG. 8, recesses 13 and 23 are formed in the center of the tip surfaces of the reinforcing bars 1 and 2, and a positioning member 6 that can be engaged with both recesses 13 and 23 is installed. As the recesses 13 and 23, those for centering used when engraving the male screws 12 and 22 on the expanded diameter portions 11 and 21 can be used. This is because when the male screws 12 and 22 are engraved by cutting with a lathe or the like, the recesses 13 and 23 for centering are formed.

  Further, although the positioning member 6 is illustrated as being formed in an elliptic spherical shape such as a rugby ball, it may be formed in a spherical shape or a shape in which two conical shapes are joined at the bottom surface portion. Further, the positioning member 6 may have a size such that the positioning member 6 is divided into the two concave portions 13 and 23 and is depressed, but may be a size in which both ends are partially engaged and the central portion is not buried. This is determined by how the distance between the end faces of the reinforcing bars 1 and 2 to be connected is set.

  As described above, according to the present embodiment, the reinforcing bars 1 and 2 in which the male screws 12 and 22 are engraved in the expanded diameter portions 11 and 12 having sufficient strength are provided via the sleeve 3 having sufficient thickness. Can be connected together. Further, as is clear from the explanation of the method of use, the connecting work is easy. In the case of the configuration in which the positioning members 6 are arranged by forming the recesses 13 and 14 on the tip end surface of the reinforcing bar, the reinforcing bars 1 and 2 are arranged so that the axes thereof are aligned with each other, and the connection by the sleeve 3 is facilitated. can do.

  The embodiments are illustrative of the invention and are not intended to be limiting. Therefore, various modifications are possible within the scope of the present invention. For example, although each of the male screws 12 and 22 and the female screw 31 is exemplified by a metric screw, the details thereof may be not only a coarse screw but also a fine screw. Alternatively, a trapezoidal screw may be used. Further, it is not limited to the screw according to the domestic standard, and a unified screw or an inch screw such as a Whitworth screw may be used. The thread pitch or thread surface area may be in accordance with the criteria of the present invention.

  Furthermore, these various screw structures may be multi-start screws such as double-start screws and triple-start screws. By using the multi-thread screw, when the male screws 12 and 22 of the reinforcing bars 1 and 2 and the female screw 31 of the sleeve 3 are screwed together, the screwing within a predetermined range can be completed by a small number of rotations. That is, in the case of a double-thread screw, the lead length is twice the pitch length, and in the case of the triple-thread screw, the lead length is three times the pitch length. The screwing can be completed by rotating 1/2 or 1/3 with respect to the single thread screw. This saves the labor of connecting the reinforcing bars at the construction site and contributes to enabling the reinforcing work in a short time.

  Below, the result of the tensile test of the reinforcing bar joint actually created is shown. As a typical example, several types of reinforcing bars will be shown. The following table shows each dimension such as the nominal cross-sectional area of the reinforcing bar, the effective cross-sectional area of the male screw and the sleeve used. In each case, a 10-pitch male screw was screwed in and tested.

  As a result of the tensile test of the reinforcing bar joints shown above, the results were that the strength was above the allowable range in all cases. As a reference example, the cross-sectional area of the expanded diameter portion is 1.4 times the nominal cross-sectional area of the reinforcing bar, and 10 pitches or more are screwed together, and the cross-sectional area is the same as that of the example, but the screwing pitch is As a result of conducting the tensile test also when the number was 9.5 or less, all were within the allowable range.

  Therefore, by screwing the male screw having the above-mentioned effective area into the sleeve by 10.5 pitch, it was possible to obtain the result that the connection state is sufficient while considering the safety factor.

1, 2 Reinforcing bar 3 Sleeve 4, 5 Lock nut 6 Positioning member 10 Reinforcing bar tip portion 10a Reinforcing bar tip 10b Reinforcing bar tip end surface 11, 12 Expanded portion 11a Small diameter portion 11b Small diameter portion end surface 11c Burr 12,22 Male screw ( (Male screw part)
13, 23 Recesses 30a, 30b Sleeve end face 31 Female screw (female screw portion)
L1, L2 Sleeve length C1, C2 Gap between rebar tips

Claims (4)

A joint method rebar which the sleeve is interposed at both ends of the reinforcing bars to be coupled to connect the two reinforcing bars,
Both of the rebars have a diameter-expanded portion at the tip of which the diameter is sufficiently expanded so that the cross-sectional area exceeds 1.5 times the nominal cross-sectional area of the rebar, and the effective cross-sectional area has a nominal area of the rebar. A male screw having a cross-sectional area of 1.5 times or more and a surface area per pitch of a portion where a thread is formed is 20% or more of the nominal cross-sectional area of the reinforcing bar is engraved in the expanded diameter portion. Is configured as
The sleeve is formed in a tubular shape, and a female screw that is screwed into the male screw is engraved on an inner diameter portion of the sleeve. is configured as being have a length that can be screwed or pitch,
A method for joining reinforcing bars, characterized in that male threads of the expanded diameter portion of the reinforcing bars are screwed into the female threads of the sleeve by 10 to 11 pitches . The method for joining reinforcing bars according to claim 1, wherein at least one of the sleeves is crimped with a lock nut that is screwed into a male screw of the expanded diameter portion. The lock nut is provided with a female screw that is screwed onto the male screw of the enlarged diameter portion at at least 4 pitches, and the enlarged diameter portion is used for screwing with the sleeve and screwing the lock nut. 3. The method for joining reinforcing bars according to claim 2, wherein male threads are continuously engraved, and at least 4 pitches are screwed into the male threads of the expanded diameter portion by the lock nut. The male screw of the enlarged diameter portion is provided with a concave portion in the center of the end surface of the enlarged diameter portion in advance, and the spherical or elliptical spherical positioning member formed to have a size corresponding to the distance between the end surfaces faces each other. 4. The reinforcing bar joint method according to claim 1, wherein the end faces of the reinforcing bars to be connected face each other so as to be engaged with the recess.

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