JP2020007729A - Fixing nut for screw reinforcement and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing nut for a screw reinforcing bar which can be manufactured at a low manufacturing cost as a result of reducing labor such as deburring during manufacturing according to a casting method. SOLUTION: In a fixing nut for a screw reinforcing bar which is open at both ends in the screwing axis direction and has a screw hole in which a female thread is formed on an inner peripheral surface, it extends from one end to the other end in the screwing axis direction. In addition, two concave grooves that open outward at both ends are formed so as to face each other and cross the female screw. [Selection diagram] Fig. 1

Description

  The present invention relates to a fixing nut for a screw rebar used when fixing a screw rebar to concrete, and a method for manufacturing the same.

  BACKGROUND ART In a reinforced concrete structure, a fixing tool called a fixing nut, a fixing metal, or the like may be used in order to fix a deformed reinforcing bar such as a screw reinforcing bar to concrete. Generally, such a fixing device is attached to an end of a deformed reinforcing bar such as a screw reinforcing bar, and then an organic or inorganic grout (material) is injected into a clearance between the deformed reinforcing bars and fixed. Used by

  Various fixing devices for fixing deformed reinforcing bars such as screw reinforcing bars to concrete have been conventionally proposed and used. For example, in Patent Literature 1 (Japanese Patent Application Laid-Open No. 2003-213841), a tubular portion having both open ends and a female screw on the inner periphery, and threading a threaded rebar in a threaded state, and a radial portion extending from the tubular portion An annular flange portion protruding outward, fixed to the screw rebar by grout filled into the clearance between the cylindrical portion and the screw rebar, and a fixing metal for fixing the screw rebar to concrete, An injection port for injecting grout is formed in the center of the portion, and an annular groove connected to the injection port is formed in the inner periphery of the center of the cylindrical portion, and an annular groove is formed before grout injection. Fixing hardware has been proposed in which a groove is continuous with the opening at both ends through a clearance between a cylindrical portion and a screw reinforcing bar.

JP 2003-213841 A

  By the way, fixing devices used when fixing deformed reinforcing bars such as screw reinforcing bars to concrete are manufactured according to conventionally known various manufacturing methods according to the size and shape thereof, and particularly, a sand mold is used. By adopting the casting method, it is possible to enjoy advantages such as a reduction in manufacturing cost. When manufacturing a nut (an anchor nut for a screw rebar; hereinafter, also simply referred to as a nut) to be screwed to an end of a screw rebar according to a casting method using a sand mold, generally, a fixing nut for a screw rebar is used. A pair of upper and lower dies for forming an outer shape and a core for forming a screw hole (and a female screw on the inner peripheral surface thereof) are used.

  However, when the fixing nut for the screw reinforcing bar is manufactured by the casting method, the manufacturing cost may be deteriorated due to the following factors. First, a core used for forming a screw hole of a nut is a shell core (core manufactured according to a shell molding method) capable of accurately forming a female screw on the inner peripheral surface of the screw hole. Is advantageously used, but such a shell core is generally formed using a pair of forming dies (upper die and lower die), and corresponds to the mold mating surface of the forming die on the core surface. Burrs may be generated even though they are minute. Since such burrs may affect the shape accuracy of the female screw in the nut as a casting, a process such as inspection is required before casting the nut, and as a result, the manufacturing cost of the nut is reduced. May worsen. In addition, when a fixing nut for a screw rebar is cast using a core and a pair of upper and lower dies, a portion of the obtained nut surface corresponding to the mating surface between the upper and lower dies is inevitably flashed. Occurs. If any such burrs remain near both ends in the screwing axial direction of the screwing holes into which the screw rebars are screwed, removal of the burrs may be hindered from screwing the nut into the screw rebars. Must be carried out with great care and, as a result, increase manufacturing costs. Further, the fixing nut for a screw rebar requires an injection hole for injecting grout (material) into a clearance between the nut and the screw rebar, but when the nut is manufactured by casting, after the casting, It is common to perform another step for forming the injection hole, and the existence of such another step has exacerbated the manufacturing cost of the nut.

  Under such circumstances, the present invention has been completed, and the problem to be solved is that labor for removing burrs at the time of manufacturing according to the casting method is reduced, and as a result, An object of the present invention is to provide a fixing nut for a screw rebar that can be manufactured at a manufacturing cost. Another object of the present invention is to provide a method capable of advantageously producing such a fixing nut for a screw rebar.

  And in order to solve such a problem, the present invention has a screw hole which is opened at both ends in the screw shaft direction and has a female screw formed on an inner peripheral surface, and the other end from one end in the screw shaft direction to the other. And two recessed grooves extending outwardly at both ends thereof are formed so as to oppose each other and cross the female screw formed on the inner peripheral surface of the screw hole. The gist of the present invention is a fixing nut for a screw reinforcing bar.

  According to the present invention, there is provided a method for manufacturing a fixing nut for a screw rebar according to the aspect having the above-described configuration, wherein 1) a molding cavity which gives an outer shape of the fixing nut for a screw rebar in a state where the mold is matched is formed; A pair of upper and lower dies are prepared, with a plane including the axis center line of the screw shaft in the screw nut for the screw reinforcing bar being prepared as a mating surface, and 2) the fixing for the screw reinforcing bar in a mated state. Forming a molding cavity that provides a male screw shape corresponding to the female screw in the nut and two convex ridges corresponding to the two concave grooves, and at a portion of the molding cavity that provides the two convex ridges. After a core having the male screw shape and the two ridges on the outer peripheral surface is formed and prepared using a pair of molding dies on which a mold matching surface is located, 3) on the outer peripheral surface of the core Formed in The core is arranged in a molding cavity formed by the upper mold and the lower mold so that each of the two ridges is parallel to the mold mating surface of the upper mold and the lower mold. The gist of the present invention is also a method of manufacturing a fixing nut for screw rebars, wherein casting is performed using the upper die, the lower die, and the core arranged as described above.

  As described above, the fixing nut for a screw rebar according to the present invention starts from the place where the two concave grooves are formed facing each other so as to cross the female screw formed on the inner peripheral surface of the screw hole. Due to the presence of the two concave grooves, when a nut is manufactured by a casting method, burrs generated due to the combination of an upper die and a lower die for shaping the outer shape of the nut are screwed into the screw rebar. In this case, it is possible to reduce the influence of the internal thread, and to effectively suppress the formation (generation) of an inaccurate female screw due to minute burrs on the core surface. In addition, the two concave grooves formed on the inner peripheral surface of the screw hole are open at both ends. After the fixing nut for the screw rebar according to the present invention is screwed to the screw rebar, grout ( Since the material can be injected, a step of providing a grout (material) injection hole in the nut after casting is not required. As described above, in the fixing nut for a screw reinforcing bar according to the present invention, when manufacturing by casting, the step of removing burrs on the nut surface, which was required in the nut according to the conventional structure, is significantly simplified, Alternatively, since it becomes unnecessary, the manufacturing cost can be kept low as a result. In addition, the two grooves, which function as injection holes for grout (material) when screwed with the screw rebar, are open at both ends in the screwing axial direction, so that grout (material) can be easily injected. In addition, the degree of grout (material) injection can be easily confirmed.

  Further, according to the method for manufacturing a fixing nut for a screw rebar according to the present invention, it is possible to manufacture the fixing nut for a screw rebar at low cost.

It is a front view showing an example of the fixing nut for screw rebars according to the present invention. It is a left view which shows an example of the fixing nut for screw rebars according to this invention. It is explanatory drawing which shows the cross section in the AA plane in FIG. FIG. 2 is a partially enlarged explanatory view of a portion B in FIG. 1. It is explanatory drawing which shows an example of the upper type | mold and lower type | mold used when casting the fixing nut for screw rebars according to this invention, (a) is a front view which shows the state which matched, (b) FIG. 3 is an explanatory view showing a cross section taken along a line CC in FIG. It is explanatory drawing which shows an example of the core used when casting the fixing nut for screw rebars according to this invention, (a) is a front view, (b) is a right view. It is explanatory drawing which shows the shaping | molding die for shaping the core shown in FIG. 6, (a) is a front view which shows the state which matched, (b) is DD plane in (a). It is explanatory drawing which shows the cross section in FIG. FIG. 7 is a partial cross-sectional explanatory view showing a state where the upper die and the lower die shown in FIG. 5 and the core shown in FIG.

  Hereinafter, the present invention will be described in detail with reference to the drawings as appropriate.

  FIG. 1 to FIG. 4 show a fixing nut (hereinafter, also simply referred to as a nut) 10 for a screw reinforcing bar according to an embodiment of the present invention. Specifically, FIG. 1 is a front view of the nut 10, FIG. 2 is a left side view, and FIG. 3 is an explanatory diagram showing a cross section that appears when cut along the AA plane in FIG. 1. FIG. 4 is an explanatory view showing a partially enlarged portion B in FIG. The back view is the same as the front view, and the right side view, the plan view, and the bottom view are the same as the left side view.

  As is clear from FIGS. 1 to 4, the fixing nut 10 for a screw rebar according to the present invention has a cylindrical shape as a whole. 1 and the left and right directions in FIG. 3 (hereinafter referred to as the screw shaft direction). The radially outer corners at both ends of the cylinder are chamfered.

  On the inner peripheral surface of the screw hole 12, a helical female screw 14 for screwing to a screw rebar (not shown) is formed. Such a female screw 14 can be easily screwed onto a target screw rebar, and corresponds to the shape of a male screw formed on the outer peripheral surface of the screw rebar so that a good screwing state can be ensured. The thread height and pitch are determined.

  And, in the fixing nut 10 for screw rebar according to the present invention, from one end in the screwing axial direction to the other end so as to cross the female screw 14 formed on the inner peripheral surface of the screwing hole 12. A large technical feature resides in that two concave grooves 16a and 16b extending toward each other and opening outward at both ends thereof are formed facing each other around a screw shaft. is there.

  That is, when the two concave grooves 16a and 16b are formed, when the fixing nut 10 for a screw rebar is manufactured according to, for example, a casting method, an upper mold and a lower mold for molding the outer shape of the nut are formed. The effect of the burr generated due to the alignment when the nut 10 is screwed onto the screw rebar can be reduced, and the female screw with inferior precision caused by the minute burr on the core surface can be reduced. Can also be effectively prevented. Further, since the two concave grooves 16a and 16b are open at both ends in the screwing axial direction, after the nut 10 is screwed into the screw rebar, the grout (material) is formed through the opening formed between the nut 10 and the screw rebar. The step of providing a grout (material) injection hole after casting is not required in the nut 10 because the injection of (1) is possible. Accordingly, when the fixing nut 10 for a screw rebar according to the present invention is manufactured by a casting method, the step of removing burrs generated on the core and the nut surface, which is required in the nut according to the conventional structure, is extremely simple. Or becomes unnecessary, and the step of forming the grout (material) injection hole becomes unnecessary, so that the manufacturing cost can be kept low. At the same time, the two concave grooves 16a and 16b which serve as a grout (material) injection hole when screwed with the screw rebar are open at both ends in the screwing axial direction, and the grout (material) In addition, the fixing nut 10 for a screw rebar according to the present invention has an advantage that the injection of the grout (material) can be easily confirmed and the degree of the injection of the grout (material) can be easily confirmed.

  Here, as shown in FIG. 4, the two concave grooves 16 a and 16 b traversing the female screw 14 are formed such that the bottom surface thereof is at a position recessed from the bottom surface of the valley constituting the female screw 14. In other words, the bottom surfaces of the two concave grooves 16a and 16b are formed so that the bottom surfaces of the two concave grooves 16a and 16b protrude radially outward of the nut 10 than the bottom surfaces of the valleys forming the female screw 14. Is preferred. By adopting such a configuration, it is possible to more advantageously receive the effects of the present invention described above. In FIG. 4 (and FIG. 1), the dotted line indicates the bottom surface of the valley constituting the female screw 14, and the amount of depression of the bottom of the concave groove (16 a, 16 b) with respect to the bottom of the valley constituting the female screw 14. (D in FIG. 4) may not be able to enjoy the effects of the present invention if it is too small, while on the other hand, if it is too large, problems such as a decrease in the strength of the nut 10 may occur. For this reason, the dent amount (d) generally depends on the size of the nut 10 and the like, but is generally about 0.5 to 3 mm. In addition, the amount of each recess in the two concave grooves 16a and 16b may be the same or different.

  Further, it is preferable that the corners on the bottom surfaces of the two concave grooves 16a and 16b have an R shape (see FIG. 4). Since the bottom has a rounded corner, when the nut 10 is used in a reinforced concrete structure, breakage due to stress concentration and the like can be advantageously prevented.

  The fixing nut 10 for a screw rebar according to the present invention is made of various metal materials, similarly to a conventional fixing tool used when fixing a deformed reinforcing bar such as a screw rebar to concrete.

  By the way, the above-described fixing nut 10 for a screw rebar can be manufactured by, for example, a casting method according to the following procedure.

  First, as the outer die, a molding cavity that gives the outer shape of the screw nut 10 for a screw rebar in the mated state is formed, and a plane including the axial center line of the screw shaft of the nut 10 is defined as a mating surface. A pair of upper mold and lower mold are prepared.

  FIG. 5 shows such an upper mold and a lower mold. FIG. 5A is a front view of the upper mold 20 and the lower mold 22 in a state where the molds are matched, and FIG. (b) is an explanatory view showing a cross section taken along the line CC in (a). As is clear from FIGS. 5A and 5B, the upper die 20 and the lower die 22 are provided with a forming part 24 for giving the outer shape of the fixing nut 10 for the screw rebar when the molds are matched, and It is configured such that a cavity 28 formed by gripping portions 26a and 26b for gripping the child is formed therein. The upper mold 20 gives the outer shape of the upper half of the nut 10 (the upper half in the vertical direction of the paper in FIGS. 1 to 3), and the lower mold 22 gives the lower half of the nut 10 (see FIG. 1). 1 to 3), the molding surface of the upper mold 20 and the lower mold 22 is formed so that the outer shape of the lower half in the vertical direction of the paper surface in FIG. It coincides with a plane including the axial center line of the screw shaft at 10.

  As the material (mold material) constituting the upper mold 22 and the lower mold 24, any of various conventionally known mold materials can be used. Sand (casting sand) is advantageously used. Although not shown in FIGS. 5A and 5B, the upper die 22 is formed with a gate and a runner for pouring the molten metal.

  On the other hand, a core for forming the female screw 14 and the two concave grooves 16a and 16b in the fixing nut 10 for screw rebar is prepared. FIG. 6 is an explanatory view showing such a core. FIG. 6A is a front view of the core 30, and FIG. 6B is a right side view of the core 30.

  As can be understood from FIG. 6, the core 30 is held in the cavity 28 of the upper mold 20 and the lower mold 22 at both ends in the direction corresponding to the screwing axis direction of the screw nut 10 for the screw reinforcement. The outer peripheral surface of a portion between the support portions 32a and 32b is provided with a male screw portion 34 corresponding to the female screw 14 in the screw hole 12 of the nut 10 and a screw. Two ridges 36a, 36b corresponding to the two concave grooves 16a, 16b in the hole 12 are formed. The dotted lines in FIGS. 6 (a) and 6 (b) indicate the portions corresponding to the mold-matching surfaces (mold-matching lines) of the mold when the core 30 is molded using the mold described below. .

  FIG. 7 shows a molding die used when molding the core 30. FIG. 7A is a front view showing a state in which a core forming die 42 composed of a pair of an upper die 38 and a lower die 40 is matched, and FIG. It is explanatory drawing which shows the cross section in the -D plane.

  As can be understood from FIG. 7, the core forming die 42 provides 1) the support portions 32 a and 32 b of the core 30 in a state where the upper die 38 and the lower die 40 are matched. Forming cavities formed by the parts 44a and 44b, 2) the part 46 of the core 30 that provides the male screw portion 34, and 3) the parts 48a and 48b of the core 30 that provide the two ridges 36a and 36b. It is configured to be. The upper mold 38 provides an upper half of the core 30 (the upper half in the vertical direction of the paper in FIGS. 6A and 6B), while the lower mold 40 provides an upper half of the core 30. Each is configured so that a lower half (a lower half in the vertical direction of the paper in FIGS. 6A and 6B) is provided. Therefore, the mating surface of the upper mold 38 and the lower mold 40 coincides with a plane including the axis center line of the core 30 (in other words, the axis center line of the screw shaft of the nut 10 as the casting). Becomes

  When the core is formed using the above-described core forming die 42 (the upper die 38 and the lower die 40), in order to accurately form the male screw portion 34, the core may be formed according to a shell mold forming method. preferable.

  The pair of upper mold 20 and lower mold 22 prepared as described above and the core 30 are subjected to mold matching as shown in FIG. FIG. 8 is a cross-sectional view of the upper mold 20, the lower mold 22, and the core 30 in the matched state when cut along a plane corresponding to the CC plane in FIG. It is an explanatory view showing a part and a ridge). At the time of such mold matching, more specifically, the cores 30 are so formed that the two ridges 36a and 36b formed on the core 30 are parallel to the mold matching surfaces of the upper mold 20 and the lower mold 22. The portions (the portions indicated by dotted lines in FIG. 8) corresponding to the mold-matching surfaces (mold-matching lines) of the core forming dies on the two protrusions 36a and 36b of 30 are the molds of the upper mold 20 and the lower mold 22. It is performed so as to coincide with the mating surface.

  Then, according to a conventionally known casting method, a molten metal is poured into a mold that has been molded as described above, solidified, and then separated from the mold, thereby forming the screw rebar shown in FIGS. 1 to 3. The fixing nut 10 is manufactured.

  The fixing nut 10 for a screw rebar obtained in this manner has two concave grooves 16a and 16b formed to face each other so as to cross the female screw 14 formed on the inner peripheral surface of the screw hole 12. In addition, due to the presence of the two concave grooves 16a and 16b, burrs resulting from the matching of the upper mold 20 and the lower mold 22 are formed in the two concave grooves 16a and 16b (more specifically, two burrs). At the two ends of the grooves 16a and 16b in the screwing direction), so that the burrs have a small adverse effect on the shape of the female screw 14 and, consequently, a small influence on the screwing of the female screw. . In addition, by disposing the core 30 with respect to the upper die 20 and the lower die 22 in accordance with a predetermined positional relationship and performing casting, formation of an inaccurate female screw due to minute burrs on the surface of the core 30 is also possible. , Can be effectively suppressed. Furthermore, the two concave grooves 16a and 16b formed on the inner peripheral surface of the screw hole 12 are open at both ends, and after the nut 10 is screwed into the screw rebar, the grout (material) is passed through the opening. The step of providing an injection hole for grout (material) in the nut after casting is not required since the injection of grout is possible. As described above, in the case of the fixing nut 10 for a screw rebar according to the present invention, when manufacturing by casting, the step of removing burrs on the nut surface, which is required in the nut according to the conventional structure, is significantly simplified. Or, since it becomes unnecessary, as a result, the production cost can be kept low. In addition, the two grooves, which function as injection holes for grout (material) when screwed with the screw rebar, are open at both ends in the screwing axial direction, so that grout (material) can be easily injected. In addition, the degree of grout (material) injection can be easily confirmed.

  As described above, one of the typical embodiments of the present invention has been described in detail. However, the present invention is not limited to the above-described specific embodiments, and those skilled in the art may use the same without departing from the spirit of the present invention. It is to be understood that various changes, modifications, improvements, and the like can be made based on the knowledge of

DESCRIPTION OF SYMBOLS 10 Fixing nut for screw reinforcement 12 Threaded hole 14 Female screw 16a, 16b Concave groove 20 Upper die 22 Lower die 30 Core 34 Male thread portion 36a, 36b Convex streak

Claims (2)

Opening at both ends in the screwing axial direction, having a screwing hole formed with an internal thread on the inner peripheral surface,
Two concave grooves extending from one end to the other end in the screwing axial direction and opening outward at both ends are formed on the inner peripheral surface of the screwing hole so as to face each other. An anchor nut for a screw reinforcing bar, which is formed so as to cross an internal thread. A method for manufacturing a fixing nut for a screw rebar according to claim 1,
A pair of upper dies, in which a molding cavity that gives an outer shape of the screw nut for a reinforcing screw in the mated state is formed, and a plane including an axis of a screw shaft of the fixing nut for the screw reinforcing is used as a mating surface. And the lower mold is prepared,
In the matched state, a forming cavity is formed that provides a male screw shape corresponding to the female screw and two convex ridges corresponding to the two concave grooves in the fixing nut for the screw rebar, and A core having the male screw shape and the two convex ridges on the outer peripheral surface is molded and prepared using a pair of molding dies in which a mold matching surface is located at a site where the two convex ridges are provided in the cavity. After
The core is formed by the upper mold and the lower mold so that each of the two ridges formed on the outer peripheral surface of the core is parallel to the mold mating surface of the upper mold and the lower mold. A method for manufacturing a fixing nut for a screw rebar, characterized in that casting is performed using an upper mold, a lower mold and a core arranged in a molding cavity to be formed.

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