JP4931236B2 - Stud manufacturing method - Google Patents

Description

  The present invention relates to a stud manufacturing method applied to, for example, a steel structure in the field of architecture and civil engineering.

  Conventionally, in a steel structure in the field of construction or civil engineering, concrete is integrated with a steel column and a steel beam in terms of fire resistance and structural strength. In this case, as a means for improving the proof stress by increasing the mutual connectivity between the members, it is common to implant a stud material called a stud bolt, a headed stud, etc. on the steel surface by arc welding. Is. As a stud of this kind, a small lump made of a highly conductive material such as aluminum is formed in the center portion of the welded side end surface (stud base) formed as a flat surface orthogonal to the shaft center on one end side of the stud body, There are known devices that are attached so that a part of the surface protrudes from the surface (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3). This metal lump plays a role as a flux that causes a deoxidation reaction during arc generation with the base metal, in addition to a role as an energizing terminal at the start of welding.

Japanese Examined Patent Publication No. 52-10648 (first page, second column, third line—same column, twenty-seventh line and FIG. 6; and second page, third column, twelveth line—same column, seventeenth line and FIG. 4) Japanese Utility Model Publication No. 57-54932 (page 1, column 2, line 1, column 21, line 21, FIGS. 3-6) Japanese Patent Publication No. 7-55352 (page 3, column 6, line 20 to page 4, column 7, line 7, FIG. 4)

  By the way, in the stud of the above-described conventional example, a concave portion having an appropriate depth is formed in advance in the center portion of the end surface on the side of the molten metal into which the metal lump is press-fitted by punching (also referred to as punch). As shown in Patent Documents 1 and 3, such a recess is generally circular in cross-sectional shape in the axial direction, and its inner peripheral surface is formed as a relatively smooth surface. This is due to the fact that the outer peripheral surface of the punch is finished to be a smooth surface in order to prevent the punch from biting into the stud body at the time of stamping. Accordingly, since the press-fitted metal lump is substantially locked to the stud body only by friction with the inner peripheral surface of the recess, there is a problem that it is easy to drop off even with a slight impact. .

  Patent Document 2 discloses a technique for forming a large number of irregularities on a wall surface by forming the recess into a cross-sectional shape other than a circle such as a star, or by forming the inner peripheral surface of the recess in a horizontal stripe shape or a spiral shape. Although disclosed, each has the following problems. That is, in the former case, the contact area with the metal block is increased as compared with the circular cross section as described above, but there is no step in the axial direction, and the contact area with the circular cross section is as follows. Similarly, it is a lock only by friction. For this reason, not much improvement can be expected in terms of prevention of dropout. In the latter case, the plastic deformation at the time of press-fitting of the metal lump can be expected to have a latching effect on a large number of steps formed in the axial direction, but the forming process is quite troublesome and the manufacturing cost is low. Therefore, it has not been put into practical use.

  Under such circumstances, a method of making a hole with a drill instead of punching has recently been widely used. In this case, since the annular cutting trace accompanying the rotation of the drill blade is formed on the inner peripheral surface of the recess, a slight engagement state occurs between the press-fitted metal lump and the metal lump There is less dropout. However, this method of forming a recess by a drill has a problem that workability is poor compared to punching and a large amount of cutting waste is generated, and is not an essential solution. .

  Therefore, the present inventors have come up with the present invention as a result of intensive studies on the problems of such conventional techniques. That is, an object of the present invention is to provide a method for manufacturing a stud that can be manufactured at a low cost without dropping off a metal block.

In order to solve the above-mentioned problems, in the stud manufacturing method according to the present invention, after forming a recess in the flat welded side end surface of the stud body, a part of the metal lump that is softer than the stud body is melted. At least a part of the opening peripheral portion of the recess of the stud body is pressed into the recess in a state of projecting from the planting end surface, and the weld side end surface near the metal lump is pressed in the axial direction. The bulging part bulges inward by plastic deformation, and the bulging part that is harder than the metal lumps bulges, so that the metal lumps are plastically deformed and enter the back side of the bulging part. It is characterized by being attached.

According to the above configuration, after forming the stud body from the rod-shaped material using an appropriate forging device, and further forming a recess on the end face on the side of the weld formed as a flat surface perpendicular to the axis on one end side Then, a metal lump having an appropriate shape and softer than the stud main body is press-fitted into the recess so that a part of the lump protrudes. And the stud main body end surface near the recessed part of a blasting side end surface, ie, the metal lump, is pressed toward the other end side of an axial center direction. By this pressing force, the opening peripheral portion of the recess is plastically deformed and bulges inward, and the opening is narrowed. On the other hand, in the case of a metal lump made of a material softer than the stud body, the peripheral portion of the opening of the recess of the stud body made of a material harder than the metal lump is on the inside. Since it is plastically deformed at the same time under the influence of bulging out , i.e., pressure from the surroundings, it also wraps around the back side of the bulging portion, so that it is securely hooked to the bulging portion.

In the present invention, a step of pressing the vicinity of the concave portion of the blast side end surface in the axial direction is added in a state where a part of the metal block protrudes from the concave portion provided on the flat blast side end surface of the stud body. As a result, the opening peripheral portion of the recess becomes a bulging portion that plastically deforms and bulges inward, and a metal lump made of a soft material located inside thereof is pushed by the bulging pressure of the bulging portion, Since it is plastically deformed and enters the back side of the bulging portion to realize the latching state, the metal lump is not dropped off, and the manufacturing cost of the stud can be reduced.

  In the stud manufacturing method according to the present invention, for example, a stud main body is formed using an appropriate forging device generally used such as a multi-stage former, and until the concave portion is formed on the flat blast side end surface, Substantially no difference from the conventional method. In addition, in this invention, it uses by the meaning including what carried out the chamfering process to the peripheral part of the stud main body generally performed with the conventional stud with the flat shaped fusion side end surface. In the present invention, in the state in which the metal block is press-fitted into the recess, the vicinity of the recess on the end surface on the side of the weld, that is, the vicinity of the metal block is pressed in the axial direction. By this pressing operation, the peripheral edge portion of the opening of the recess is plastically deformed and bulges inward, while the metal lump is also plastically deformed due to the effect of the formation of the bulge and the back side of the bulge It has a technical feature in that it enters into a state of engagement. The metal lump applied to the present invention is a softer metal than the stud body. Furthermore, it is a metal having a lower melting point and a stronger reducing power than the metal constituting the stud body and the base material. For example, for iron, which is a representative material of the stud body and the base material, aluminum, zinc, etc. What is necessary is just to select suitably according to the metal used as object. The shape is not particularly limited, but a spherical shape, a pointed columnar shape, or the like is preferable. The type of stud is not limited to a headed stud, and there is no particular limitation in the shape of the main body, such as a seismic reinforcement stud made of deformed reinforcing bars. As for the method of forming the bulging portion in the recess on the end surface of the stud body on the side of the blasting, for example, a cylindrical or annular protrusion is pressed in the axial direction with an appropriate punch formed on the tip surface, and plastic deformation is performed. Thus, the entire periphery of the peripheral edge portion of the opening may be bulged, or the bulged portion may be formed by partially plastically deforming with a punch having a cross-shaped or single-letter-shaped projection.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a partial cross-sectional front view showing an embodiment of a stud obtained by the manufacturing method of the present invention. The illustrated stud 1 is made of a metal such as an aluminum sphere at the center of an end surface 12 (welded side end surface) that is flat and serves as a stud base on the side opposite to the head 11 of the stud body 10. The lump 13 is fixed in a state where a part thereof is buried. FIG. 2 is an enlarged view of the end portion of the stud body 10 in FIG. 1 on the side of implantation, and a cross section in which the description of the metal lump 13 is omitted in order to clearly show the shape of the recess 14 that holds the metal lump 13. It represents as. Here, a part of the metal lump 13 is inserted into a substantially hemispherical recess 14 provided on the end surface 12 of the stud body 10, and the inner surface near the entrance of the recess 14, that is, the entire circumference of the peripheral edge portion of the opening. It extends over the back side of the bulging portion 14a which is formed over and swells inward so as to narrow the opening portion, and fills the inside of the concave portion 14 with almost no gap. Thus, in the stud 1 obtained by the present invention, the metal lump 13 is securely locked by engaging with the bulging portion 14a of the stud body 10 on the back side, and falls off the stud body 10. It will disappear.

  Next, a method for manufacturing the stud 1 using a multistage former will be described with reference to FIGS. The multi-stage former is generally composed of a plurality of dies attached to a fixed base (not shown) and a plurality of punches attached to a reciprocating ram (not shown). In FIG. 3, a rod-shaped material 2 such as an iron wire having a predetermined outer diameter cut to a predetermined length is first inserted into the die 20 leaving a predetermined length portion serving as a head, and is supported by a support pin 21 on the rear end side. Supported. In this state, the punch 22 moves from the tip side, the tapered inner space 22a is fitted on the protruding end of the rod-shaped material 2, and the head is preformed by pressing with the punch pin 23. .

  Next, as shown in FIG. 4, the head is further formed by the die 24 and the punch 25 in the unit of the next process. Here, while the rear end side is in contact with the concave portion forming pin 26 inserted through the die 24, the head is further formed by the punch pin 27, and an intermediate concave portion is formed on the rear end surface of the rod-shaped material 2. . Note that the shape of the pressing portion 26a in the concave portion forming pin 26 is a hemispherical shape with the tip side somewhat flattened, and as shown in an enlarged view in FIG. It is formed in a corresponding shape.

  Subsequently, as shown in FIG. 6, the head of the rod-shaped material 2 is finally formed by the die 28 and the punch 29 in the next process unit.

FIG. 7 shows an outline of the press-fitting work of the metal lump 13. In this case, an aluminum sphere is used as the metal lump 13. Here, the head body 11 side of the stud main body 10 is inserted into the punch case 33 and supported by the punch pins 34. In this state, the through hole 35a of the driving die 35 is placed in alignment with the concave portion 14 of the stud body 10 so that the axis of each other is aligned, and the aluminum sphere 13 is press-fitted into the concave portion 14 with the driving pin 36. The aluminum balls 13 are supplied one by one into the through hole 35a from a storage portion 37 provided at the tip side portion of the driving die 35. By this press-fitting operation, the aluminum sphere 13 enters the inside of the recess 14. After that, the stud main body 10 into which the aluminum sphere 13 is press-fitted is pushed forward by the punch pin 34 after the punch case 33 is retracted, and the driving pin 36 is also returned to the original position by the spring 38 for the next work. Prepare. The stud body 10 inserted into the recess 14 in a state in which the aluminum sphere 13 protrudes is pressed around the entrance of the recess 14 in the axial direction by an appropriate bulging portion forming pin. The vicinity is plastically deformed and bulges inward over the entire circumference, forming an annular bulge 14a (see FIG. 2). In particular, in the manufacturing method according to the present invention, when the bulging portion is formed, that is, when the opening peripheral portion of the recess 14 bulges inward so that the inlet is narrowed, the stud body 10 The metal lump made of a soft material is pushed inward along with its bulging, so that it is easily plastically deformed and enters the back side of the bulging portion. The engagement state of the concavo-convex relationship is realized.

  FIG. 8 shows another embodiment of the method for forming the bulging portion provided on the stud body side, and shows a cross section in which the metal lump is omitted as in the above embodiment. Here, in a state in which a metal lump (not shown) is press-fitted into the recess 42 of the stud main body 41, the periphery of the recess 42 near the inlet is annularly pressed by an appropriately shaped bulge forming pin. As a result, the end surface of the stud body 41 is recessed to form an annular groove 42a, and a bulging portion 42b is generated over the entire periphery of the opening peripheral portion with the plastic deformation. Even in this case, the metal lump is also plastically deformed due to the influence when the bulging portion 42b is formed, and as a result, enters the back side of the bulging portion, and is brought into an engaged state.

  Furthermore, in the embodiment of the bulging portion shown in FIG. 9, each axial center side part is plastically deformed and bulges inward due to the influence of the four recesses 62 a formed on the end surface of the stud body 61. A bulging portion 62b is formed. In this case, the metal lump (not shown) is also plastically deformed as the bulging portion 62b is formed in the same manner as in the above-described embodiments, and enters the back side of the bulging portion 62b. Become.

  In each of the embodiments described above, the concave portion of the stud main body has been described as having a circular cross section in the axial direction. However, it is possible to make this a polygonal shape, or to make the metal block other than a sphere. Of course, various modifications within the technical idea of the present invention are possible.

It is a fragmentary sectional front view which shows one Example of the stud manufactured by this invention. It is a principal part expanded sectional view of the said stud. It is explanatory drawing which shows the manufacturing process of a stud main body. It is explanatory drawing which shows the next process of FIG. FIG. 5 is an enlarged cross-sectional view of a main part of an intermediate stud body formed in the process of FIG. 4. It is explanatory drawing which shows the next process of FIG. It is explanatory drawing which shows the press injection operation | work of a metal lump. It is a principal part expanded sectional view which shows the other example of a bulging part. It is a principal part expanded sectional view which shows the other example of a bulging part.

DESCRIPTION OF SYMBOLS 1 ... Stud, 2 ... Rod-shaped material 10, 41, 61 ... Stud main body, 11 ... Head, 12 ... End surface on the side of a molten metal, 13 ... Metal lump, 14, 42, 62 ... Recessed part, 14a, 42b, 62b ... bulge part, 20, 24, 28 ... dice, 22, 25, 29 ... punch, 26 ... recess forming pin, 33 ... punch case, 35 ... die for driving

Claims (1)

After forming a recess in the flat welded end surface of the stud body, a metal lump that is softer than the stud body is press-fitted into the recess so that a part protrudes from the welded end surface. By pressing the end face on the side of the weld near the ingot-like material in the axial direction, at least a part of the peripheral edge of the opening of the recess of the stud body is plastically deformed to form a bulging portion that bulges inward, and is made of metal. A method of manufacturing a stud, characterized in that the metal lump is plastically deformed by entering the back side of the swollen portion when the swollen portion that is harder than the lump is swollen , and is engaged.

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