JP4361511B2 - Boss member and manufacturing method of boss member - Google Patents

Description

  The present invention provides a boss member that is interposed between a workpiece and a workpiece to be fastened to the workpiece and is fastened with a fastening member such as a screw or a nut, The present invention relates to a boss member in which a head outer peripheral edge portion is not warped by a recess formed at a position in contact with the head portion, and a method for manufacturing the boss member.

  When an electronic board is laminated to reduce the thickness of a product and a cover or a display unit is attached to the front surface, a relatively thin work is used for attaching these objects to be fastened. A screw is usually used to attach an object to be fastened such as a cover or a display unit to such a workpiece. However, the thickness of the workpiece is not sufficient to screw this screw directly onto the workpiece, and the fixing strength is low. It was in decline. In order to prevent this, a boss member having sufficient strength for screwing and attaching a screw is fixed to a workpiece, and the object to be fastened is attached by screwing the screw to the boss member. .

  Recently, many types of boss members have been used. For example, a head having a slightly larger diameter than a mounting hole (not shown) formed in the workpiece and a erected on the head. And a shaft portion having a diameter that can be fitted into the hole portion is integrally formed of a metal material, and the outer peripheral surface of the shaft portion is a groove portion having a square cross-section over the entire circumference at the boundary portion with the head portion. Is formed. In addition, a knurl or serration for rotation prevention is formed on the outer peripheral surface of the head, and a bottomed cylindrical shape that can be screwed into the shaft portion or a through hole shaped pilot hole that penetrates from the shaft portion to the head portion is formed There is something that has been.

An example of such a boss member similar in structure and action is shown in Japanese Patent Application Laid-Open No. 2002-181014. This is an insert nut 101 as shown in FIG. In this case, a metal insert nut 101 is press-fitted into the mounting hole of the resin case, and the mounting hole 108 has an insertion guide hole 108a on the inlet side and an insertion guide hole 108b on the outlet side. The inner diameter of the insertion guide hole 108a is larger than the inner diameter of the insertion guide hole 108b. On the other hand, the metal insert nut 101 has a large-diameter portion 102 fitted in the insertion guide hole 108a on the inlet side, a lid portion 103 fitted in the insertion guide 108b on the outlet side, and a large outer periphery. A groove portion 105 formed between the diameter portion 102 and the lid portion 103 is formed, and the groove portion 105 is filled with a resin material deformed by the press-fitting operation of the insert nut 101. In this case, the lid portion is press-fitted from the guide hole 108a side in the press-fitting operation, and the lid portion 103 protrudes from the resin case in a state where the resin material is filled in the groove portion 105. Structure.
JP 2002-181014 A

  However, when a structure having such a configuration and action is adopted in a boss member 201 as shown in FIG. 9 and the groove 205 is formed by rolling, the serration 207 formed on the outer periphery of the head 203 is formed. The outer peripheral edge of the head is warped from the end face of the head by this rolling groove processing, and when this is directly pressed into the mounting hole of the work 203 with the leg 202 first, the groove 205 is filled with the work meat. The serration portion 207 also fits into the workpiece, but the meat of the workpiece is not sufficiently filled or fitted at any location. For this reason, when the boss member is prevented from coming off and is prevented from rotating, when the screw is screwed onto the boss member, the fastening force cannot be withstood, so that rotation may occur or the workpiece may come off. Further, since the warpage occurs in this way, a gap (S) is generated between the serration portion formed on the outer peripheral edge of the head and the work, and strong fixation cannot be expected. Furthermore, since the warp has occurred on the end face of the head, even if this boss member is press-fitted into the work, the head does not become flat with respect to the work surface. Problems such as detracting from aesthetics have arisen.

  An object of the present invention is to eliminate such a problem and obtain a boss member that does not warp the head even if a recess is formed by rolling at a position in contact with the head of the shaft portion. It is to obtain a manufacturing method for providing a member.

An object of the present invention is to provide a shaft portion 2 into which a fastening member is screwed, a head portion 3 integrally formed with the shaft portion 2 and having a serration portion 7 having a larger diameter than the shaft portion 2, and a shaft portion 2 in contact with the head portion 3. A boss member provided with a groove-shaped recess 5 on the outer periphery, and a head outer peripheral edge portion having a serration portion 7 larger than a shaft portion diameter at the time of head forging in the head forging step 30 is a shaft portion side. In the next rolling step 50, a workpiece material formed by tilting in a hemi umbrella shape and having the serration portion 7 and the head outer peripheral edge portion tilting in an umbrella shape is formed on the outer periphery of the shaft portion 2 in contact with the head portion 3. The concave portion 5 is formed by rolling along the head 3, and at the same time, the outer peripheral edge of the umbrella-shaped head is pushed toward the head end surface, so that the outer peripheral edge of the umbrella-shaped head is similar to the head end surface. This is achieved by providing a boss member that is formed flat.

In order to achieve this object, in addition to the above configuration , the recess has a side wall 6 inclined at least on one side so that the bottom side is narrow and the open side is wide in the cross section along the axis. It is easy to fit in and can be firmly fixed.

In addition, the object of the present invention is to provide a shaft portion 2 into which a fastening member is screwed, a head portion 3 integrally formed with the shaft portion 2 and having a serration portion 7 having a larger diameter than this, and a shaft in contact with the head portion 3. In the boss member manufacturing method in which the groove-shaped concave portion 5 is provided on the outer periphery of the portion 2, in the head forging step 30 , the outer peripheral edge of the head that is larger than the shaft portion diameter and has the serration portion 7 is moved to the shaft portion side. is inclined to form an umbrella shape, followed by the serration portion 7 and the processing material having a tilted umbrella head portion outer peripheral edge in the next rolling step 50, the head outer circumferential edge portion of the umbrella-shaped A concave portion 5 is formed along the head on the outer periphery of the shaft portion 2 in contact with the head 3 having a head, and at the same time, the umbrella-shaped outer peripheral edge of the head is pushed toward the head end surface, thereby the umbrella-shaped head providing child a manufacturing method of the boss member outer peripheral portion has a similarly flat formed Ru configuration and the head end face Also it is achieved by.

Also in this manufacturing method, the head has an acute angle between the seating surface of the outer peripheral edge of the head and the outer peripheral surface of the shaft in the head forging step 30, and in the next rolling step 50, the head 3 When the concave portion 5 is formed by rolling in the shaft portion 2 in contact with the shaft portion , the angle formed with the outer peripheral surface of the shaft portion is as close as possible from an acute angle to a right angle, so that the purpose can be sufficiently obtained.

According to the present invention, even if the concave portion is formed along the outer periphery of the shaft portion close to the head portion by rolling, the end surface of the head portion does not warp at the outer peripheral edge portion, and the boss member is When press-fitting into the mounting hole, the end surface of the head is substantially flat with respect to the surface of the workpiece. This is because by forming the concave groove, the meat of the material moves to the outer peripheral edge portion of the head once formed into an umbrella shape in the head forging process. For this reason, when the boss member is press-fitted into the mounting hole of the workpiece, there is almost no gap between the workpiece and the head of the boss member, and a close-contact state is obtained, and the anti-rotation and retaining action is ensured. , Mechanical performance is improved. Further, since the workpiece and the boss member are brought into close contact with each other in this manner, even in an energized state, there is no short circuit in this portion, and stable electrical performance can be obtained. Furthermore, since the head of the boss member is flat, it does not swell or dent even if it is press-fitted into the workpiece, so that it does not stand out and the aesthetics of the product is improved. Moreover, since such processing can be performed without changing the number of steps simply by changing the shape of the punch in the forging step for forging the head, there is no increase in cost, and this recess is formed by cutting as in the past. Compared to the above, there are specific effects such as being suitable for mass production.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2, reference numeral 1 denotes a boss member according to the present invention, which includes a shaft portion 2 and a head portion 3 having a diameter larger than that of the shaft portion 2. The shaft portion 2 of the boss member 1 is provided with a prepared hole 4 formed in the shape of a bottomed cylindrical hole on the center line. The pilot hole 4 is formed in a bottomed cylindrical hole shape from the shaft end of the shaft portion 2 toward the head portion 3, but in addition to this, a through-hole shape penetrating from the shaft end to the head end (not shown) It may be. Since a screw (not shown) is screwed into the pilot hole 4 and combined, this diameter is substantially equal to or less than the effective diameter of the thread formed on the screw leg. It has become. In this embodiment, a pilot hole 4 is provided in the shaft portion as a fastening member and a screw is fastened. Instead of this screw, a nut (not shown) is fastened to the outer periphery of the shaft portion. May be.

  Further, the neck portion between the shaft portion 2 and the head portion 3, that is, the shaft portion 2 in contact with the head portion 3 has a smaller diameter and a width of about ½ of the thickness of the head portion 3. A recess 5 having an outer circumferential groove shape is formed along the outer periphery of the shaft portion, and the recess 5 has a side wall 6 inclined at least one or both sides so that the bottom side is narrow and the open side is wide in the cross section along the axis. Yes. The recess 5 is a groove into which the meat of the workpiece (W) is fitted when the boss member 1 is press-fitted and fixed in a mounting hole (not shown) of the workpiece (W) such as a metal plate. W) is a retaining structure.

  The head portion 3 having a diameter larger than the diameter of the shaft portion 2 is continuously and integrally provided on the neck portion, and the head portion 3 is radially spaced from the center thereof at equal intervals on the circumference. A serration portion 7 having a shape in which a plurality of chevron-shaped protrusions protrudes is formed. The serration portion 7 has a serrated chevron shape on the outer periphery, but is not limited to this shape. For example, the serration portion 7 may have a petal shape as long as the anti-rotation action is generated when the workpiece is pressure-fixed to the workpiece. There may be.

  Such a boss member is manufactured by the following steps. That is, as shown in FIG. 4, a predetermined pilot hole 4 is formed in the drilling step 20. Subsequent to this drilling step 20, a head forging step 30 is arranged, and as shown in FIG. 5, forging is applied to the outer peripheral edge of the head 3 of the primary work material 11 as shown in FIG. A serration portion 7 is formed. The receiving piece 31 in this step has a support hole 32 corresponding to the outer diameter of the shaft portion of the boss member 1, and an extrusion pin 33 is inserted into the support hole 32 so as to be slidable in the axial direction.

  A chevron-shaped head outer periphery forming hole 34 corresponding to the serration portion 7 is formed at the tip of the receiving piece 31 and is larger than the support hole 32, and corresponds to the bottom of the head outer periphery forming hole 34. The surface from the edge of the support hole 32 to the outside has a conical shape inclined so that the head outer periphery forming hole 34 becomes deeper. This is a shape for the purpose of obtaining a final shape for forming the outer peripheral edge of the head as a product in the rolling step 50 described later. The primary work material 11 of this shape is the rolling step 50. It is to be corrected. Further, the outer peripheral surface of the head outer periphery forming hole 34 forming the serration portion 7 is a surface substantially perpendicular to the conical surface. The end surface has a shape slightly larger than the head seat surface. The depth of the head outer periphery forming hole 34 is slightly shallower than the thickness of the head 3 of the boss member 1.

  On the other hand, a pressure punch 35 is disposed on the center line of the support hole 32, and the tip of the pressure punch 35 has a diameter larger than the outer diameter of the serration portion 7 on the head end surface side of the boss member 1. It has a surplus forming hole 36 that forms a surplus part 12 thinner than the serration part 7 formed by the head outer periphery forming hole 34. The depth of the hole 36 is smaller than the dimension obtained by subtracting the depth of the head outer peripheral forming hole 34 from the thickness of the head 3 of the boss member 1, for example, about ½ of this dimension. Subsequent to the surplus hole forming hole 36, the pressure punch 35 is formed with a truncated cone-shaped head end surface forming hole 37 having a slightly deep depth, that is, the depth of the remaining half of the above dimensions. As a result, the forged head 3 has a shape in which the center side swells in a slight trapezoidal or arcuate shape. The sum of the depths of the head outer periphery forming hole 34, the surplus forming hole 36, and the head end surface forming hole 37 is set to be the thickness of the head 3.

  Subsequent to the head forging process 30, a trimming process 40 is arranged. In the trimming step 40, as shown in FIG. 6, the trimming punch 41 is moved and positioned on the center line of the support hole 32 of the receiving piece 31, and the centers of the trimming punches 41 coincide with each other. It contacts the surplus part end surface of the head 3 of the primary work material 11 obtained by the process. In this trimming process 40, the outer peripheral shape of the serration portion 7 formed in advance by the head forging process 30 and the inner shape of the trimming punch 41 are adjusted and arranged, and the push pin 33 is arranged on the front trimming punch side. And the trimming punch 41 bites into the surplus portion 12 by pushing out the primary work material 11, and as shown in FIG. 3, the secondary portion in which the serration portion 7 is formed on the entire outer peripheral surface of the head 3. A processed material 13 is obtained.

Next, a rolling process 50 is provided. In this process, the secondary processed material 13 having the serration part 7 is moved to the head 3 with a rolling die (not shown) close to the head 3 with the head 3 facing up. A recess 5 is formed on the outer periphery of the neck by rolling the part 2. As a result, an annular recess 5 is formed on the outer periphery of the shaft portion 2 and the head outer peripheral edge portion having the serration portion 7 of the head portion 2 moves the surplus material of the material due to the formation of the recess toward the head side. Since the end surface side of the head 2 is pushed, the umbrella-shaped outer peripheral edge stands slightly on the head end side. For this reason, the angle formed by the seating surface and the shaft portion of the outer peripheral edge of the head approaches as much as possible from an acute angle to a right angle, and as shown in FIG. 1, the end surface of the head 2 is substantially flush with the boss. The member 1 is obtained.

  In such a configuration, a pilot hole 4 is drilled in a drilling step 20 in a material 10 set to a predetermined length so that a head 3 larger than the shaft portion 2 can be obtained in advance, and the material 10 is removed from the head 10. Supply to the forging process 30. In the head forging step 30, as shown in FIG. 5, the material 10 is press-fitted into the support hole 32 of the receiving piece 31 by the pressure punch 35, and at the same time, the extrusion pin having the insertion tip of the material 10 in a predetermined position. Although it contacts the end of 33, the pressure punch 35 further moves, so that the material 10 fills the head outer periphery forming hole 34. On the other hand, the material 10 on the pressure punch side also fills the surplus hole forming hole 36, and this pressurizing action has a serration portion 7 on the shaft portion side, and on the head outer peripheral edge portion on the head end side. A primary portion having a thin head portion 12 and a head portion 3 in which a head portion 3 which is slightly swollen is formed on the center side of the head portion, so-called a head outer peripheral portion inclined in an umbrella shape. A processed material 11 is obtained. When the primary work material 11 is obtained, the pressure punch 35 moves backward, and then the trimming punch 41 is moved and positioned on the center line of the receiving piece 31.

  In the trimming step 40, the inner shape of the trimming punch 41 matches the shape of the forming hole of the receiving piece 31 in advance, and the trimming punch 41 moves to the receiving piece side as shown in FIG. 11 abuts on the surplus portion 12 of the eleventh, the push pin 33 moves in the direction of the trimming punch 41 and pushes out the primary work material 11 from the support hole 32 of the piece 31. As a result, as shown in FIG. 3, the blank portion 14 is removed from the outer portion 12, and the trimming punch 41 forms the same shape as the serration portion 7. In this way, the secondary processed material 13 having the serrations 7 formed on the entire outer periphery of the head 3 and the outer peripheral edge of the head being umbrella-shaped is then supplied to the rolling process 50.

  In this rolling process 50, the head 3 having the serration portion 7 is supplied between the rolling dies (not shown) in a state where the shaft portion 2 is suspended, and the secondary work material 13 includes the head seating surface. Since the concave portion 5 is formed on the side shaft portion 2 by rolling, the outer peripheral edge of the head that is umbrella-shaped is pushed and the seat surface of the outer peripheral edge of the head is generated, so the entire head end surface and the seat surface are The boss member 1 as shown in FIGS. 1 and 2 is completed substantially perpendicular to the shaft portion 2. When this boss member 1 is press-fitted into the mounting hole of the workpiece (W) with the shaft portion 2 first, the head 3 is press-fitted into the workpiece, and the workpiece is inserted into the serration portion 7 and the recess 5 as shown in FIG. The meat of the boss member 1 is sufficiently fitted, and the boss member 1 has the function of preventing rotation and retaining with respect to the workpiece (W).

It is principal part sectional drawing of a boss | hub member. It is a right view of FIG. It is principal part sectional drawing which shows the state in which a serration part is formed. It is a flowchart which shows the manufacturing process of a boss member. It is principal part sectional drawing of a head forging process. It is principal part sectional drawing of a trimming process. It is principal part sectional drawing which shows the fitting state of this invention and a workpiece | work. It is principal part sectional drawing which shows the prior art example of this invention. It is principal part sectional drawing which shows another prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boss member 2 Shaft part 3 Head part 4 Pilot hole 5 Recessed part 6 Side wall 7 Serration part 10 Material 11 Primary processing material 12 Remaining material part 13 Secondary processing material 14 Dregs 20 Drilling process 30 Head forging process 31 Receiving piece 32 Support hole 33 Extrusion pin 34 Head outer periphery forming hole 35 Pressure punch 36 Additional thickness forming hole 37 Head end surface forming hole 40 Trimming process 41 Trimming punch 50 Rolling process W Workpiece

Claims (4)

A shaft portion (2) to which the fastening member is screwed, a head portion (3) integrally formed with the shaft portion and having a serration portion (7) having a larger diameter than this, and a groove on the outer periphery of the shaft portion in contact with the head portion A boss member provided with a recessed portion (5) having a shape, and an outer peripheral edge of the head having a serration portion larger than the diameter of the shaft at the time of head forging in the head forging step is umbrella-shaped toward the shaft In the next rolling step, a work material having the serration part and the head outer peripheral edge part inclined in an umbrella shape is formed in the outer periphery of the shaft part in contact with the head, and a recess is formed along the head. rolling the umbrella-like head outer periphery simultaneously formed by pressing the head end side, it has a similar flat-formed structure and the umbrella-shaped head outer periphery the head end face boss member, characterized in that there. 2. The boss member according to claim 1, wherein the recess has a side wall (6) inclined at least on one side so that the bottom side is narrow and the open side is wide in a cross section along the axis. 3. A shaft portion (2) to which the fastening member is screwed, a head portion (3) integrally formed with the shaft portion and having a serration portion (7) having a larger diameter than this, and a groove on the outer periphery of the shaft portion in contact with the head portion In the method of manufacturing a boss member provided with a concave portion (5) having a shape, in the head forging step (30), the outer peripheral edge of the head having a diameter larger than the shaft portion and having the serration portion is inclined toward the shaft portion. In the next rolling step (50), the processed material having an umbrella shape and subsequently having the serration portion and the head outer peripheral edge portion inclined in an umbrella shape has the umbrella-shaped outer peripheral edge portion. A concave portion is formed along the head on the outer periphery of the shaft portion that is in contact with the head, and at the same time, the umbrella-shaped outer periphery of the head is pushed toward the head end surface side so that the umbrella-shaped outer periphery of the head is The manufacturing method of the boss | hub member characterized by setting it as the structure formed flat similarly to a head end surface. In the head forging process, the angle formed by the seating surface of the outer peripheral edge of the head and the outer peripheral surface of the shaft is an acute angle, and in the next rolling process, the shaft that is in contact with the head can be rolled. 4. The method for manufacturing a boss member according to claim 3, wherein when the recess is formed, an angle formed with the outer peripheral surface of the shaft portion approaches from an acute angle to a right angle as much as possible.

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