JP2007278437A - Blind rivet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blind rivet of the type opened radially outward by dividing a rivet body shank, at low cost and made suitable for fastening a soft member. <P>SOLUTION: A mandrel 1 has a fall preventing part 18 formed in a larger diameter than a portion 22, between a head 14 and a rupturable part 17 before assembled to a rivet body 2, and the shank 9 has a reduced diameter part 23 with an inner diameter smaller than the outer diameter of the fall preventing part by drawing from the outer surface of the shank, between a flange part 10 and a position corresponding to the rupturable part 18 after assembled. The shank 9 is formed with a plurality of longitudinal grooves 25 for cutting on the outer surface of a head 14 side portion, spaced in an outer peripheral direction after assembled. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a blind rivet, and more particularly to a blind rivet of a type in which an end portion of a rivet main body shaft portion is cut into a plurality of portions and the divided portions are expanded radially outward. Insert the rivet body into the mounting hole of the wall or the like forming the wall, expand the rivet body shaft end, and clamp it between the flange of the rivet body and attach it to the mounting member The present invention relates to a blind rivet capable of fixing a member or the like.

  A blind rivet comprising a shaft and a hollow metal rivet body comprising a flange at one end of the shaft portion and a metal mandrel that is longer than the rivet body through which the grip portion extends through the rivet body is well known. For example, there is an advantage that a plurality of panels can be connected by work only from one side. A blind rivet described in US Pat. No. 4,620,825 (Patent Document 1) includes a rivet body having a hollow shaft portion having a flange formed at one end thereof, and a head having a diameter larger than the shaft portion inner diameter of the rivet body. And a mandrel having an outer diameter that passes through the rivet body is assembled so that the head is adjacent to the other end of the shaft opposite to the flange and the grip portion extends from the flange. . The mandrel head is formed with a blade that protrudes toward the end surface and inner wall of the other end of the shaft portion and extends in the longitudinal direction of the shaft portion. When the grip portion of the mandrel is gripped with a fastening tool and pulled strongly from the flange, the mandrel head The edge of the shaft part is expanded by, for example, dividing the shaft end part into four parts while cutting the other end part of the shaft part. A plurality of attached members such as panels and attachment members are sandwiched between the four expanded shaft portions and the flanges, and are connected to each other. The state where the end portion of the rivet body shaft portion is expanded while being cut open is similar to a state in which a flower opens when viewed from the end face side, and is also called a petal-type blind rivet.

US Pat. No. 4,620,825 (Japanese Utility Model Laid-Open No. 60-159214) U.S. Pat. No. 4,897,003 (JP-A-2-21011) US Patent Application Publication No. 2005/0180837 (Japanese Patent Laid-Open No. 2005-226807) US Pat. No. 5,044,850 (JP-A-4-228910) JP 2000-213516 A

  In the blind rivet disclosed in Patent Document 1, the shape of the head and its vicinity is complicated because the mandrel is formed with a blade. In the blind rivet described in Patent Document 2, the mandrel head is formed in a cylindrical shape having a conical surface, and the blade facing is not formed on the side facing the end surface of the rivet main body shaft. Do not need. Instead of forming the blade, a longitudinal groove is formed inside the end portion of the rivet body shaft, and the end of the rivet body is formed by incising the longitudinal groove portion with a mandrel head and pushing it outward in the radial direction. Divided and expanded radially outward.

  In the blind rivet of Patent Document 3, a blade that protrudes toward the end surface and inner wall of the rivet body shaft portion and extends in the longitudinal direction of the shaft portion is formed on the mandrel head, and the mandrel is gripped by the grip portion and pulled out from the flange. Thus, the blade of the mandrel head is expanded while incising the other end portion of the shaft portion. The rivet body shaft portion has a reduced diameter portion that is smaller in diameter than the other portion by the restriction from the outer surface side at the portion adjacent to the blade of the mandrel head, so that the inner wall of the rivet body shaft portion is in close contact with the outer surface of the mandrel The blade of the mandrel head bites into the end portion of the rivet body shaft portion stably and surely, and the rivet body shaft portion end portion is reliably incised.

  The blind rivet of Patent Document 4 has a fan-shaped projection divided into two on the outer periphery of the portion adjacent to the head of the mandrel, and engages and fixes the fan-shaped projection on the inner side of the rivet body shaft. A fixing means is formed. When the rivet body of the blind rivet is inserted into the mounting hole of the member to be fastened and the mandrel is pulled out, the shaft part of the rivet body is expanded and the member to be fastened is sandwiched between the expanded portion and the flange of the rivet body. Even if the fastening member is connected and the mandrel tip portion is broken, the remaining mandrel portion is fixed to the rivet body and the hollow portion of the rivet body fills the mandrel, so that the fastening force is improved.

  The blind rivet disclosed in Patent Document 5 has a rivet body shaft for facilitating the installation of the tool when it is inserted and caulked upward from below into the member of the ceiling portion, so that it does not fall out even if the hand is released after inserting. A suspension member is provided between the section and the mandrel head. This suspension member is formed of a soft synthetic resin and uses its elasticity, and has a diameter larger than that of the rivet main body shaft and elastically deforms and passes through the mounting hole of the fastened member. Engage with the upper surface edge of the rivet to prevent the rivet body from falling off. Also, in the rivet body, a slit is formed at a portion where the thick shaft portion of the mandrel adjacent to the head is inserted to be a temporary fixing portion, and the thick shaft mandrel portion is elastically engaged with the temporary fixing portion. It is configured not to fall out.

  In the blind rivet described in Patent Document 1, the head and the vicinity thereof must be formed in a complicated manner in order to form the blade in the mandrel, which increases the cost. In the blind rivet described in Patent Document 2, a plurality of longitudinal grooves must be formed inside the end portion of the rivet body shaft, which increases the number of processing steps and time, and the cost increases in this respect. In particular, it is possible to form the longitudinal groove formed on the inner side to a certain depth, but in order to enable expansion even with a weak pulling force, the depth of the longitudinal groove should be made deeper at the front and shallower at the far side. It is difficult to control. Therefore, when the member to be fastened is a soft member, a strong pulling force must be applied, and the soft member may be damaged or broken, which is not suitable for fastening the soft member. The head of the mandrel of the blind rivet of Patent Document 3 has a simpler shape than the case of Patent Document 1, but it must be formed in a slightly complicated shape to form a blade. Moreover, it is required that the pulling force of the mandrel when expanding the rivet body is strong, which is somewhat unsuitable for fastening the soft member. In the blind rivet described in Patent Document 4, the engaging means must be formed inside the rivet main body shaft portion, and like the blind rivet of Patent Document 2, the overall cost of the blind rivet is increased. The blind rivet of Patent Document 5 requires an elastic suspension member, which not only increases the cost, but also causes the suspension member to become an obstacle in storage. Further, the expansion of the rivet body shaft of the blind rivet is divided in a state where it is bent at the base of the slit, so that a high fastening force cannot be expected and it is not suitable for fastening a soft member.

  Accordingly, an object of the present invention is to provide a blind rivet of a type that divides a plurality of portions while cutting the end portion of the rivet body shaft portion and expands the divided portions outward in the radial direction at a low cost. An object of the present invention is to provide a blind rivet suitable for fastening a member.

  To achieve the above object, the present invention provides a hollow rivet body comprising a hollow cylindrical shaft part and a flange formed at one end of the shaft part, and a head having a diameter larger than the inner diameter of the shaft part of the rivet body. And a mandrel having an outer diameter penetrating the rivet main body and formed in a rod shape longer than the rivet main body and having a grip portion formed on the end side opposite to the head, and the mandrel and the rivet main body are a flange, Is mounted so that the head portion is adjacent to the other end of the opposite shaft portion and the grip portion extends from the flange, and the mandrel is located away from the head and within the shaft portion of the rivet body. A small-diameter breakable portion is formed in the portion to be accommodated, and when the grip portion is strongly pulled out from the flange, the head portion cuts the other end of the shaft portion and its adjacent portion in the longitudinal direction and radially outwards. Expansion The blind rivet is configured to be pulled into the shaft portion and to be broken at the breakable portion when a predetermined pulling force is exceeded, and the mandrel is separated from the head and the breakable portion before assembly to the rivet body. Between the breakable portion and the grip portion, and a rivet body shaft portion corresponding to the breakable portion of the mandrel after the mandrel is assembled. The portion between the position and the flange has a reduced diameter portion that is reduced to an inner diameter that is smaller than the outer diameter of the drop-off prevention portion by a restriction from the outer surface side of the shaft portion, and the drop-off prevention portion is provided by pulling out the mandrel. Provided is a blind rivet characterized in that a mandrel portion including a drop-off preventing portion is fixed to the rivet body even after the breakable portion is broken by being press-fitted into the reduced diameter portion of the rivet body.

  In the blind rivet described above, since the mandrel head does not require a blade, the shape of the mandrel may be simple, and the shape of the shaft portion of the rivet body is also the rivet body after the rivet body and mandrel are assembled. Since the reduced diameter portion can be formed from the outer surface of the shaft portion, the cost can be reduced and a low cost blind rivet can be provided. Further, since the mandrel portion including the drop-off preventing portion is fixed to the rivet body, the expanded portion of the rivet body shaft portion is strengthened in maintaining the expanded shape, and a high fastening force is maintained for a long time. In addition, since the mandrel part including the drop-off prevention part is fixed to the rivet body, even if vibration is applied from the fastened member to the blind rivet, the mandrel part is immobile in the rivet body, Absent.

  In the blind rivet, the mandrel head has a surface facing the other end of the rivet body shaft as a conical slope, and the conical slope is formed on a smooth surface without a cutting edge. The drop-off prevention part is formed of a cylindrical part extending from the head to the breakable part, and the drop-off prevention part has a structure in which a plurality of circumferential grooves are formed in the middle to reinforce the fixing force after press-fitting into the reduced diameter part. it can.

  In the blind rivet, after the mandrel is assembled to the rivet body shaft, a plurality of longitudinal grooves for incision are spaced apart in the outer circumferential direction on the outer surface of the other end in contact with the mandrel head and the subsequent portion. By pulling out the mandrel, the mandrel head expands radially outward while splitting the shaft part by cutting the rivet body shaft part with the longitudinal groove as an incision line, and as it is pulled into the rivet body shaft part The divided part of the shaft part is formed in an arch shape. As a result, even if the mandrel head does not have a blade, the rivet body shaft portion can be smoothly expanded even with a pulling force that is not strong, so even if the member to be fastened is a soft member, the soft member is not damaged. High fastening force can be obtained. The longitudinal groove may be formed in the rivet body shaft before the mandrel is assembled to the rivet body. Each of the longitudinal grooves is formed so as to be deepest in a portion adjacent to the head and tapered so as to become shallower as it is away from the head. In particular, four longitudinal grooves are formed at equal intervals along the outer peripheral surface, and the rivet body is formed of aluminum or an aluminum alloy.

  In the blind rivet, the flange is formed in such a thickness that the drop-off preventing portion does not protrude from the flange after the mandrel is broken at the breakable portion. This can prevent the mandrel from protruding from the flange after fastening.

  The present invention relates to a hollow rivet body comprising a hollow cylindrical shaft part and a flange formed at one end of the shaft part, and a rivet body having a head having a diameter larger than the inner diameter of the shaft part of the rivet body at the end. It consists of a mandrel that has a penetrating outer diameter and is formed in a rod shape longer than the rivet body, and a grip portion formed on the end opposite to the head, and the mandrel and rivet body are the shafts on the opposite side of the flange The mandrel is mounted at a position away from the head and accommodated in the shaft portion of the rivet body. A small-diameter breakable part is formed, and when the grip part is strongly pulled out from the flange, the head part is opened in the longitudinal direction by cutting the other end of the shaft part and its adjacent part in the longitudinal direction and expanding in the radial direction. Withdrawal It is a configuration that is broken at the breakable portion exceeds a predetermined pulling force, to provide a method of manufacturing a blind rivet. In this method, before assembling the mandrel and the rivet body, the mandrel part between the head and the breakable part is formed as a drop-off prevention part having a larger diameter than the part extending from the breakable part to the grip part, After the mandrel and rivet body are assembled, the shaft part of the rivet body between the position corresponding to the breakable part of the mandrel and the flange is drawn from the outer surface side of the shaft part to remove the fall-off prevention part. A reduced diameter portion that is reduced in diameter to an inner diameter smaller than the diameter is formed. In this method, a plurality of longitudinal grooves for incision are formed on the outer surface of the rivet shaft portion at the other end in contact with the mandrel head and the subsequent portion, spaced apart in the outer circumferential direction.

  Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a mandrel 1 of a blind rivet according to an embodiment of the present invention. FIG. 2 shows a rivet body 2 of a blind rivet according to an embodiment of the present invention. FIG. 3 shows a blind rivet 3 according to an embodiment of the present invention in which a mandrel 1 and a rivet body 2 are assembled. 4 is a cross-sectional view of the blind rivet 3 of FIG. 3 taken along the line AA. FIG. 5 shows a state in which the fastened member 6 in which the closed space 5 is formed is connected to another fastened member 7 using the blind rivet 3.

  In FIG. 1, a mandrel 1 is formed of a cylindrical rod-shaped metal longer than a rivet body 2, and is made of, for example, a hard steel wire. In FIG. 2, the rivet body 2 is formed of a hollow cylindrical metal and is made of a softer material than the mandrel 1, for example, aluminum or an aluminum alloy. As shown in FIG. 3, the blind rivet 3 is assembled such that the mandrel 1 and the rivet body 2 extend from the flange of the rivet body 2 through the hollow portion of the hollow rivet body 2. Become.

  As shown in FIG. 2, the rivet body 2 includes a hollow shaft portion 9 and a large-diameter flange 10 at one end of the shaft portion 9, and is formed in a hollow shape so that the mandrel 1 is accommodated in the hollow portion. Is formed. Before the assembly shown in FIG. 3, the rivet body 2 is formed in the shape of FIG. Specifically, the shaft portion 9 is formed in a hollow cylindrical shape, and the flange 10 is formed in a hollow disk shape. The inner diameter of the hollow portion 11 of the shaft portion 9 and the flange 10 is set so that the mandrel 1 can penetrate freely including a large-diameter portion (described later). Further, the thickness 13 of the flange 10 is set to such a thickness that the mandrel portion remaining in the rivet body 2 does not protrude from the flange 10 after the mandrel 1 is pulled out and broken.

  At one end of the mandrel 1, a head portion 14 having a larger diameter than the end portion 13 of the rivet body shaft portion 9 on the side opposite to the flange is formed. As shown in FIG. 1, the length of the mandrel 1 is considerably longer than the rivet body shaft portion 9 and protrudes from the rivet body flange 10, and the protruding portion is a gripping member at the tip of a fastening tool (not shown). It is set so that it can be gripped. A grip portion 15 is formed on the mandrel 1 on the end side opposite to the head portion 14 so as to be gripped by the fastening tool. The tip of the mandrel 1 is tapered to facilitate insertion into the fastening tool.

  The mandrel 1 is formed with a breakable portion 17 having a smaller diameter than other portions in a portion accommodated in the rivet body shaft portion 9. The breakable portion 17 is a portion that breaks when a certain pulling force is exceeded when the mandrel 1 is pulled out with a fastening tool. The pulling force before breaking is applied to the rivet body shaft portion 9 from the head 14 and becomes a force for deforming the shaft portion 9 of the rivet body 2. Therefore, the breaking resistance force of the breakable portion 17 can be determined by the force that deforms the rivet body shaft portion 9. The mandrel portion gripped by the broken fastening tool can be collected in the fastening tool collection box. The position of the breakable portion 17 is arbitrary, but if it is formed at the position shown in the embodiment, most of the mandrel 1 can be recovered, so that the recovery rate can be maintained high.

  The mandrel 1 will be further described. Before the assembly to the rivet body 2, that is, in the state shown in FIG. 1, the mandrel 1 is formed between the head portion 14 and the breakable portion 17 so as to have a larger diameter than the portion extending from the breakable portion 17 to the grip portion 15. The fall prevention part 18 is provided. Although the drop-off prevention part 18 may be formed as a cylinder extending from the head part 14 to the breakable part 17, it is preferable that two spaced circumferential grooves 19 are formed in the middle as shown in FIG. As a result, the drop-off prevention portion 18 improves the axial movement-preventing force after press-fitting into the reduced diameter portion (described later) of the rivet body shaft portion 9, and the drop-off prevention portion 18 has a force to adhere to the rivet body shaft portion. Can be big. Note that the number of the circumferential grooves 19 is not limited to the two illustrated, and may be two or more. The head portion 14 of the mandrel 1 is formed in a shape in which two truncated cones are overlapped as a whole, and a surface 21 facing the end portion 13 of the rivet body shaft portion 9 is formed as a conical slope, and the conical slope 21 is a cutting blade. Not formed on a smooth surface. The portion 22 from the breakable portion 17 to the grip portion 15 is formed in a simple round bar shape.

  The rivet body 2 will be described with reference to FIG. The rivet body shaft portion 9 is a throttle from the outer surface side of the shaft portion 9 to a portion between the position corresponding to the breakable portion 17 of the mandrel 1 and the flange 10 after the mandrel 1 is assembled to the rivet body 2. It has a reduced diameter portion 23 that is reduced in diameter to an inner diameter smaller than the outer diameter of the drop-off prevention portion 18 by processing. The diameter-reduced portion 23 is reduced to an inner diameter smaller than the outer diameter of the drop-out preventing portion 18 because the outer diameter of the drop-out preventing portion 18 of the mandrel 1 is a mandrel portion on the grip portion 15 side from the breakable portion 17, that is, a round shape. This is because the rod portion 22 is formed to have a larger diameter than the outer diameter and is drawn by the round rod portion 22. When the mandrel 1 is pulled out by the presence of the reduced diameter portion 23 and the dropout prevention portion 18 is press-fitted into the reduced diameter portion 23 of the rivet body, the dropout prevention portion 18 is included even after the breakable portion 17 is broken. The mandrel portion is fixed to the rivet body 2 by pressure bonding. The circumferential groove 19 improves the axial movement blocking force after press-fitting, and increases the force with which the drop-off prevention part 18 adheres to the rivet body shaft part.

  As shown in FIG. 3, after the mandrel 1 is assembled to the rivet body 2, the rivet body shaft portion 9 has an end portion 13 in contact with the mandrel head 14 and an outer surface from the end portion toward the flange 10. A plurality of longitudinal grooves 25 for incising so as to divide the shaft portion 9 by pulling out the mandrel 1 are formed apart from each other in the outer peripheral direction. As shown in FIG. 4, in the embodiment, four vertical grooves 25 are formed at equal intervals along the outer peripheral surface. The number of the longitudinal grooves 25 can be set to an arbitrary number of 2 or more as long as it can be cut so as to divide the shaft portion 9. The pulling force of the mandrel 1 acts on the end 13 of the shaft portion 9 from the mandrel head 14, and the shaft portion 9 is incised with the longitudinal groove 25 as an incision line to divide the shaft portion 9. The head portion 14 expands the portion of the divided shaft portion 9 radially outward, and the shaft portion is formed into an arch shape as the head portion 14 is drawn into the rivet body shaft portion 9. Accordingly, even if the mandrel head 14 does not have a blade, the rivet body shaft portion 9 can be smoothly expanded even with a pulling force that is not strong. Therefore, even if the fastened member is a soft member, the soft member is damaged. Without this, a high fastening force can be obtained. As shown in FIG. 3, each of the longitudinal grooves 25 is formed so as to be deepest in a portion adjacent to the head portion 14 and tapered so as to become shallower as it is away from the head portion 14. By forming in this way, the rivet body shaft portion 9 can be expanded smoothly even with a relatively weak pulling force. Further, since the vertical groove 25 having such a depth can be formed by an operation from the outer surface of the shaft portion 9, it can be easily performed.

  In the illustrated example, the longitudinal groove 25 is formed after the mandrel 1 is assembled to the rivet body 2, but the longitudinal groove is formed before the mandrel 1 is assembled to the rivet body 2. It can also be formed on the shaft portion 9. Also in that case, each longitudinal groove is formed in a taper so that it is deepest in a portion adjacent to the head 14 and becomes shallower as it is away from the head 14.

  As described above, in the manufacture of the blind rivet 1 according to the present invention, before the assembly of the mandrel 1 and the rivet main body 2, the mandrel portion between the head 14 and the breakable portion 17 is separated from the breakable portion 17. Is formed as a drop-off prevention portion 18 having a diameter larger than that of the portion 22 extending to the grip portion 15. After the mandrel 1 and the rivet body 2 are assembled as shown in FIG. 3, the rivet body shaft portion 9 is attached to the shaft portion between the position corresponding to the breakable portion 17 of the mandrel 1 and the flange 10. Drawing is performed from the outer surface side of the portion 9 to form a reduced diameter portion 23 that is reduced in diameter to an inner diameter smaller than the outer diameter of the drop-off preventing portion 18. In addition, after the mandrel 1 and the rivet body 2 are assembled, the rivet body shaft portion 9 has a plurality of longitudinal portions for incision on the outer surface of the end portion 13 that contacts the mandrel head 14 and the shaft portion that follows the end portion 13. The grooves 25 are formed apart from each other in the outer peripheral direction. Each of the longitudinal grooves 25 is formed so as to be deepest in a portion adjacent to the head 14 and tapered so as to become shallower as it is away from the head 14. By these, it is possible to provide a blind rivet of a type that divides the rivet body shaft portion into a plurality of parts while cutting the end portion of the rivet main body at an extremely low cost, and expands the divided portions outward in the radial direction. Also provide blind rivets suitable for.

  With reference to FIG. 5, an operation of connecting the fastened member 6 that forms the closed space 5 to another fastened member 7 using the blind rivet 3 will be described. Here, the fastened member 6 is a soft member such as plastic. The grip 15 of the blind rivet 3 (FIG. 3) is held by a fastening tool (not shown), the head 14 and the shaft 9 are inserted into the mounting holes of the mounting member 7 and the fastened member 6, and the flange 10 is positioned so as to be in contact with the mounting member 7. In this state, the mandrel 1 is pulled out from the flange 10 with a force that is strong enough to break at the breakable portion 17. As the mandrel 1 is pulled out, even if the outer diameter of the drop-off prevention part 18 is larger, the mandrel including the drop-off prevention part 18 is press-fitted into the smaller inner diameter part of the reduced diameter part 23 of the rivet body 2. The portion is fixed to the rivet body 2 after being crimped and broken at the breakable portion 17. The circumferential groove 19 improves the axial movement blocking force after press-fitting, and the force with which the drop-off prevention part 18 adheres to the rivet body shaft part is further increased.

  The strong pulling force described above also causes the mandrel head 14 to be pressed against the end of the rivet body shaft 9 and the shaft 9 is incised in the closed space 5 along the longitudinal groove 25 to move radially outward. And the portion 26 is expanded radially outward. The divided expanded portion 26 is strongly engaged with the inner wall of the fastened member 6 while being deformed into an arch shape in the closed space 5. The arch-shaped deformation is promoted by each of the longitudinal grooves 25 being tapered so as to become deepest at a portion adjacent to the head portion 14 and become shallower as it moves away from the head portion 14. Since the flange 10 is in contact with the fastened member 7, the fastened member 6 and the fastened member 7 are connected to each other. The blind rivet 3 is convenient because it can be fastened even in a closed space as described above. Further, even if the fastened member forming the closed space is a soft member, the split and expanded portion of the shaft portion 9 is deformed into an arch shape and engages with the inner wall of the fastened member. The deformation at the time of fastening to the member can be prevented.

  As shown in FIG. 5, since the mandrel portion including the drop-off preventing portion 18 is fixed to the rivet body 2, the expanded portion 26 of the rivet body shaft portion 9 is strengthened to maintain its expanded shape, and has a high fastening force. Will be maintained for a long time. In addition, since the portion of the mandrel 1 including the drop-off preventing portion 18 is fixed to the rivet body 2, even if vibration is transmitted from the fastened member 6 or the fastened member 7 to the blind rivet 3, the mandrel portion remains in the rivet body. 2 is stationary and no abnormal noise is generated.

It is a front view of the mandrel of the blind rivet which concerns on one Embodiment of this invention. It is a half section front view of the rivet main part of the blind rivet concerning one embodiment of the present invention. It is a front view which shows the rivet main body of the blind rivet which concerns on one Embodiment of this invention with a half cross section. FIG. 4 is a sectional view taken along line AA in FIG. 3. It is the half cross-section front view which fastened the blind rivet of FIG. 3 so that two to-be-fastened members might be connected.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mandrel 2 Rivet main body 3 Blind rivet 5 Closed space 6, 7 Fastening member 9 Shaft part 10 flange 11 Hollow part 13 Flange end (other end)
14 Mandrel head 15 Grip portion 17 Breakable portion 18 Fall-off prevention portion 19 Circumferential groove 22 Round bar portion 23 Reduced diameter portion 25 Vertical groove 26 Divided expanded portion

Claims (10)

A hollow rivet body composed of a hollow cylindrical shaft portion and a flange formed at one end of the shaft portion, and a head portion having a diameter larger than the inner diameter of the shaft portion of the rivet body at the end portion and penetrating through the rivet body The mandrel is formed in a rod shape having an outer diameter that is longer than the rivet body and a grip portion is formed on the end side opposite to the head part. The mandrel and the rivet body are opposite to the flange. The head is disposed adjacent to the other end of the shaft portion on the side, and the grip portion extends from the flange, and the mandrel is positioned away from the head and A breakable portion having a small diameter is formed in a portion accommodated in the shaft portion of the rivet body, and when the grip portion is strongly pulled out from the flange, the mandrel has the head portion and the other end of the shaft portion. Drawn into the shaft portion while spreading radially outward by incising the adjacent portions in the longitudinal direction, is configured to be broken at the breakable portion exceeds a predetermined pulling force, the blind rivet,
Before the assembly to the rivet body, the mandrel has a drop-off prevention part formed between the head part and the breakable part and having a larger diameter than the part from the breakable part to the grip part. Have
After the mandrel is assembled, the rivet main body shaft portion is formed at the portion between the flange corresponding to the breakable portion of the mandrel and the flange by the restriction from the outer surface side of the shaft portion. Having a reduced diameter portion reduced to an inner diameter smaller than the outer diameter of
By pulling out the mandrel, the drop-off prevention part is press-fitted into the reduced diameter part of the rivet body, and the mandrel part including the drop-off prevention part is fixed to the rivet body even after the breakable part is broken.
A blind rivet characterized by that.   2. The blind rivet according to claim 1, wherein the mandrel head has a conical inclined surface formed toward the other end of the rivet body shaft, and the conical inclined surface is formed on a smooth surface without a cutting edge. A blind rivet characterized by   3. The blind rivet according to claim 1, wherein the drop-off prevention portion is formed by a cylindrical portion extending from the head portion to the breakable portion, and the drop-off prevention portion has a plurality of circumferential grooves formed in the middle. A blind rivet characterized by having a structure that reinforces the fixing force after press-fitting into the reduced diameter portion. In the blind rivet according to any one of claims 1 to 3,
After the mandrel is assembled to the rivet body shaft portion, a plurality of longitudinal grooves for the incision are spaced apart in the outer circumferential direction on the outer surface of the other end and the subsequent portion in contact with the mandrel head. By pulling out the mandrel, the mandrel head expands radially outward while dividing the shaft portion by cutting the rivet body shaft portion with the longitudinal groove as an incision line, and the rivet body As the shaft portion is drawn, the divided portion of the shaft portion is formed into an arch shape.
A blind rivet characterized by that. In the blind rivet according to any one of claims 1 to 3,
Before assembling the mandrel, a plurality of longitudinal grooves for the incision are spaced apart in the outer peripheral direction on the outer surface of the other end that contacts the mandrel head and the subsequent portion of the rivet main body shaft. When the mandrel is pulled out, the mandrel head is expanded radially outward while the rivet body shaft portion is cut with the longitudinal groove as an incision line to divide the shaft portion, and the rivet body shaft As the part is pulled into the part, the divided part of the shaft part is formed into an arch shape,
A blind rivet characterized by that.   6. The blind rivet according to claim 4, wherein each of the longitudinal grooves is formed so as to be deepest in a portion adjacent to the head and tapered so as to become shallower with distance from the head. Blind rivet to do.   The blind rivet according to any one of claims 4 to 6, wherein the vertical grooves are formed at equal intervals along the outer peripheral surface, and the rivet body is formed of aluminum or an aluminum alloy. , Featuring blind rivets.   The blind rivet according to any one of claims 1 to 7, wherein the flange is formed to a thickness that prevents the drop-off preventing portion from protruding from the flange after the mandrel is broken at the breakable portion. , Featuring blind rivets. A hollow rivet body composed of a hollow cylindrical shaft portion and a flange formed at one end of the shaft portion, and a head portion having a diameter larger than the inner diameter of the shaft portion of the rivet body at the end portion and penetrating through the rivet body The mandrel is formed in a rod shape having an outer diameter that is longer than the rivet body and a grip portion is formed on the end side opposite to the head part. The mandrel and the rivet body are opposite to the flange. The head is disposed adjacent to the other end of the shaft portion on the side, and the grip portion extends from the flange, and the mandrel is positioned away from the head and A breakable portion having a small diameter is formed in a portion accommodated in the shaft portion of the rivet body, and when the grip portion is strongly pulled out from the flange, the mandrel has the head portion and the other end of the shaft portion. In a blind rivet manufacturing method, the adjacent portion is cut in the longitudinal direction and is drawn into the shaft portion while expanding outward in the radial direction, and is broken at the breakable portion when a predetermined pulling force is exceeded. There,
Before assembling the mandrel and the rivet body, the mandrel part between the head and the breakable part is used as a drop-off prevention part having a larger diameter than the part extending from the breakable part to the grip part. Forming,
After the mandrel and the rivet body are assembled, the rivet body shaft portion between the flange and the position corresponding to the breakable portion of the mandrel is drawn from the outer surface side of the shaft portion. Forming a reduced diameter portion that is reduced in diameter to an inner diameter smaller than the outer diameter of the drop-off prevention portion,
A method for producing blind rivets, comprising: The method of claim 9, wherein
Forming a plurality of longitudinal grooves for the incision in the outer circumferential direction on the outer surface of the rivet main body shaft portion at the other end contacting the mandrel head and the subsequent portion;
A method characterized by comprising.

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