JP2019136750A - Electrode structure and energization heating method - Google Patents

Abstract

To provide an electrode structure which energizes and heats a fastened member for fastening without cracking by a self-drilling type rivet, and can partially temper the fastened member.SOLUTION: A first electrode assembly 30a of an electrode structure comprises a first electrode member 31a having a first electrode base part 32a and a first electrode contact part 33a extending upward from one end of the first electrode base part, and a first insulating chip 35a having a first insulating chip contact part 36a extending upward from the other end of the first electrode base part, in which the second electrode assembly 30b is in a state in which four directions are inverted to the first electrode assembly, a second insulating chip contact part 36b and a second electrode contact part 33b extend downward, a part of a fastened member 52 is sandwiched between the first electrode contact part and the second insulating chip contact part, another part of the fastened member is sandwiched between the first insulating chip contact part and the second electrode contact part, the fastened member is allowed to pass between the first electrode contact part and the second electrode contact part and an electric current flows through the fastened member, and a joint part of the fastened member is tempered.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electrode structure of an electric heating device for heating and tempering a joint portion of a member to be fastened before fastening when fastening a plurality of members to be fastened using a self-piercing type (self-piercing) rivet. The present invention relates to an electric heating method. In particular, when fastening a member to be fastened made of a hard material such as a high-tensile steel plate or a poorly spreadable material such as a high-strength aluminum plate, the electrode is heated and tempered to reduce the hardness and improve the spreadability. Concerning structure.

  The self-piercing rivet has a large-diameter head and hollow legs that hang from the head. The self-piercing rivet has an advantage that a plurality of members to be fastened can be easily fastened only by driving in the rivets without processing holes for inserting bolts or the like for fastening in advance to the members to be fastened.

  Self-drilling rivets are suitable for fastening aluminum body panels that are unsuitable for welding. The weight of automobile bodies has been reduced, and aluminum bodies have also been adopted, and the demand for self-drilling rivets is increasing. In particular, the self-piercing rivet is driven so that the upper (punch side) fastened member penetrates, but the lower (receiving side) fastened member adjacent to the die does not penetrate and stays therein. Therefore, no rivet through-hole is formed on the surface of the receiving member to be fastened. Therefore, there is an advantage that the sealing performance of the receiving side fastened member is not impaired, and the self-piercing rivet cannot be seen from the receiving side fastened member side.

When using a conventional self-drilling rivet fastening device to fasten a fastened member such as a high-strength steel plate or high-strength aluminum plate, the tip of the leg of the self-drilling rivet is punched When the member to be fastened is driven into the member to be fastened and the member to be fastened is deformed by the concave portion of the die, the member to be fastened may not withstand plastic deformation, and cracking may occur. In particular, cracks often occur in the lower fastening member.
In addition, in a fastened member such as a super high-strength steel plate whose lower fastened portion plate is hard, the self-piercing rivet may not enter and may be buckled and fastened.

Patent Document 1 discloses a self-piercing rivet joining apparatus that joins a magnesium plate material and an aluminum plate material with self-piercing rivets. The joint part to be joined by the self-piercing rivet is heated to a heating temperature of 280 to a solidus line C. The self-piercing rivet joining apparatus includes a die that abuts on a joined portion of the magnesium plate material, a die heating means embedded in the die, a punch that abuts on the joined portion of the aluminum plate material, and a punch heating means embedded in the punch. . In one example, the die heating means and the punch heating means are electric heaters.
In Patent Document 1, the heat generated by the die heating means can be transmitted to the joint through the die, and the heat generated by the punch heating means can be transmitted to the joint through the punch. The heat generated by the die heating means and the punch heating means is efficiently transmitted to the joint.

However, in the joining apparatus of Patent Document 1, an electric heater is disposed on the punch and an electric heater is disposed on the die, which increases costs.
Moreover, since the electric heater of patent document 1 heats not only a junction part but the wide range around junction parts, such as die | dye, a punch, and a rivet, a heat | fever spreads in the whole self-piercing rivet joining apparatus, and heating of a junction part is carried out. Is inefficient, and the sliding part such as the punch of the self-piercing rivet joining apparatus is heated and worsened. Further, the rivet may be heated and the strength may be lowered, so it is clear that the rivet lacks practicality.
Patent Document 1 is a method of bonding with a self-piercing rivet in a state where the bonded portion is heated to a solidus temperature of ° C, and is not a method of tempering the bonded portion.

  Patent Document 2 discloses a method for manufacturing a vehicle body part in which spot welding is performed on an overlapped portion in which flanges of a first member and a second member are overlapped. This method passes through two processes, an electric heating process and a spot welding process. In the electric heating process, a softened portion having a spread that has been tempered by heating using an electric heating apparatus is formed around the nugget forming portion where the nugget is formed in the spot welding process. In the subsequent spot welding process, spot welding is performed by applying the welding electrode of the spot welding apparatus to the nugget formation portion. In the spot welded portion after the spot welding is performed, a nugget forming portion and a softened portion having a spread around the nugget forming portion are formed. Since the softened portion around the nugget forming portion has a certain width, no softening peak is formed, and stress concentration can be avoided.

  However, the spot welding of Patent Document 2 is to form a tempered softened part in the energization heating process and to form a nugget in the center of the softened part in the spot welding process. That is, the members are spot-welded, and the joints of the members are not tempered for fastening with self-drilling rivets.

  Patent Document 3 discloses a method of energizing and heating a press-formed product formed into a predetermined shape by pressing a steel plate. A steel plate is formed into a predetermined shape by hot pressing to form a press-formed product. The press-molded product is quenched by being held in a press mold for a predetermined time. Next, a pair of three-dimensional electrodes having a three-dimensional shape along an arbitrary cross section of the press-molded product is arranged, and the press-molded product is heated by energizing between the three-dimensional electrodes. Tempering is applied to the energized portion of the press-molded product by energization heating with the three-dimensional electrode.

In Patent Document 3, by using a three-dimensional electrode, any part of a press-molded product can be energized and heated under any condition. As a result, the strength distribution of the press-molded product can be freely designed.
However, Patent Document 3 is a method in which an arbitrary portion of a press-molded product is energized and heated by a three-dimensional electrode, and is not softened and joined by a self-piercing rivet.

  Therefore, when fastening a fastened member with poor spreadability with a self-piercing rivet, only the minimum necessary part of any joint of the fastened member is baked before fastening so that the fastened member does not crack. There has been a demand for an electric heating device that returns and improves the spreadability and its electrode structure.

JP 2010-188383 A JP 2017-131916 A JP 2013-244507 A

  It is an object of the present invention to provide a fastened member such as an ultra-high-strength steel plate with a self-drilling type rivet, in which the self-drilling type rivet cannot enter, buckle, and has poor ductility. An object of the present invention is to provide an apparatus and an electrode structure for tempering by energizing and heating a joint portion of a member to be fastened in order to perform fastening so that cracks do not occur.

In order to achieve this object, according to the electrode structure of the present invention, the first electrode assembly has a first electrode contact portion extending upward from one end of the flat electrode base and upward from the other end. The first insulating chip contact portion extends. The second electrode assembly is disposed upside down and left and right above the first electrode assembly. A second insulating chip contact portion extends downward from one end of the flat electrode base, and a second electrode contact portion extends downward from the other end.
The member to be fastened is sandwiched between the first electrode contact part and the second insulating chip contact part, and between the first insulating chip contact part and the second electrode contact part, and the member to be fastened is energized and heated for tempering. .

According to a first aspect of the present invention, there is provided a first electrode member made of a conductive material, which includes a first electrode base portion and a first electrode contact portion extending upward from one end portion of the first electrode base portion. A first electrode assembly having a first insulating tip contact portion extending upward from the other end of the first electrode base and comprising a first insulating tip insulated from the first electrode base;
A second electrode member made of a conductive material having a second electrode base and a second electrode contact portion extending downward from the other end of the second electrode base; and the second electrode base A second electrode assembly having a second insulating tip contact portion extending downward from one end portion, and comprising a second insulating tip insulated from the second electrode base portion;
The second insulating chip contact portion of the second electrode assembly is located above the first electrode contact portion of the first electrode assembly,
The second electrode contact portion of the second electrode assembly is located above the first insulating chip contact portion of the first electrode assembly,
At least one of the first electrode assembly and the second electrode assembly can move in a vertical direction,
A part of a member to be fastened is sandwiched between the first electrode contact portion and the second insulating chip contact portion, and between the first insulating chip contact portion and the second electrode contact portion, the In the electrode structure, a current can be passed through the fastened member between the first electrode contact portion and the second electrode contact portion with the other part of the fastened member being sandwiched.

A part of the fastened member can be sandwiched between the first electrode contact portion and the second insulating chip contact portion, and the fastened portion is sandwiched between the first insulating chip contact portion and the second electrode contact portion. If the other part of the member can be sandwiched, no current flows between the first electrode contact portion and the second insulating chip contact portion, and the first insulating chip contact portion and the second electrode contact portion No current flows between the two.
When a current can be passed through the fastened member between the first electrode contact portion and the second electrode contact portion,
The positions of the first electrode contact portion and the second electrode contact portion are separated, and a current can be passed through the portion between the first electrode contact portion and the second electrode contact portion of the member to be fastened. be able to.
The portion of the member to be fastened that is energized and heated is tempered, the hardness is lowered, and the spreadability is improved. Therefore, when the part heated and tempered by the energized member is fastened with a self-piercing rivet, the driving load decreases, and the tip of the leg of the self-piercing rivet enters the fastening part of the fastened member. Can be easily joined.

  It is preferable that the first insulating chip and the second insulating chip are made of an insulating material.

  When the first insulating chip and the second insulating chip are made of an insulating material such as ceramic, the structure is simple and can be reliably insulated.

  It is preferable that the first electrode assembly and the second electrode assembly have the same shape and are attached upside down and horizontally.

  When the first electrode assembly and the second electrode assembly have the same shape, the number of parts is reduced, and the cost can be reduced.

A second aspect of the present invention is an energization heating method for heating a fastening portion of a fastened member to be fastened by a self-piercing rivet using an energization heating device,
The energization heating device includes a first electrode assembly disposed below the fastened member, a second electrode assembly disposed above, a power source, wiring, and a switch,
The first electrode assembly includes a first electrode contact portion having a first electrode member made of a conductive material, a first insulating chip contact portion, and being insulated from the first electrode member. Consisting of an insulating chip,
The second electrode assembly includes the second electrode contact portion, and includes a second electrode member made of a conductive material, a second insulating chip contact portion, and is insulated from the second electrode member. Consisting of two insulating chips,
The first electrode contact portion and the second insulating chip contact portion are disposed to face each other,
The first insulating chip contact portion and the second electrode contact portion are disposed to face each other.
The electric heating method is
(a) The member to be fastened is arranged between the first electrode assembly and the second electrode assembly, and the position of the fastening portion is intermediate between the first electrode contact portion and the second electrode contact portion. To align
(b) sandwiching one side of the fastening portion of the fastened member between the first electrode contact portion of the first electrode assembly and the second insulating chip contact portion of the second electrode assembly;
(c) At the same time, the first insulating chip contact portion of the first electrode assembly and the second electrode contact portion of the second electrode assembly sandwich the side opposite to the one side of the fastening portion. ,
(d) energization heating comprising a step of passing a current between the first electrode contact portion and the second electrode contact portion, energizing and heating the fastening portion, and tempering the fastening portion. Is the method.

  When the upper side of the first electrode contact part is pressed by the second insulating chip contact part and the upper side of the second insulating chip contact part is pressed by the second electrode contact part, the first electrode contact part and the second electrode contact part Since the current flows through the fastened member between them, the fastening portion through which the current of the fastened member flows can be heated by energization.

According to the present invention, a self-drilling rivet is used to fasten a fastened member having poor spreadability so that cracking does not occur. Structure can be provided.
With the current heating device of the present invention, the joint portion of the fastened member can be heated and tempered, and even a hard fastened member such as an ultra-high-strength steel plate can be fastened with a self-piercing rivet. Even when a bad fastened member is fastened, it is possible to suppress cracking of the fastened portion of the fastened member.

It is an enlarged view of the part which fastens the self-piercing rivet of the self-piercing rivet fastening device. It is an expanded sectional view after fastening a member to be fastened with a self-piercing type rivet. It is sectional drawing which shows the electrode structure of the self-heating heater by embodiment of this invention. It is a top view of one electrode assembly of the electrode structure of the electric heating apparatus of FIG. FIG. 5 is a front view of the electrode assembly of FIG. 4. FIG. 5 is a right side view of the electrode assembly of FIG. 4. It is the schematic of the electrode assembly vicinity of an electric heating apparatus. It is a hardness test result after carrying out electroheating to the to-be-fastened member on various conditions. It is the schematic of the electric heating apparatus which can carry out electric heating to several fastening parts.

With reference to the drawings, a self-piercing rivet fastening method by the self-piercing rivet fastening device of the present invention will be described.
FIG. 1 is an enlarged view of a portion for fastening a self-piercing rivet 10 of a self-piercing rivet fastening device. The self-piercing rivet fastening device 1 includes a C-shaped frame (not shown), and a die 20 is fixed to the lower part of the C-shaped frame. A nose 27 movable in the vertical direction is attached to the upper part of the C-shaped frame. A chuck member that chucks the head 11 of the self-piercing rivet 10 is attached to the inside of the nose 27. A punch 28 for driving the self-piercing rivet 10 is disposed in the center hole of the chuck member.
The clamped members 51 and 52 can be clamped between the upper surface of the die 20 and the lower surface of the nose 27.

In FIG. 1, the self-piercing rivet 10 is disposed in the center hole of the nose 27, and the punch 28 is disposed on the self-piercing rivet 10.
The self-piercing rivet 10 has a large-diameter head 11 and a cylindrical leg 12 depending from the head 11. The lower end of the leg 12 is a leg tip 13 with a narrow width. The material of the self-piercing rivet 10 is selected according to the material of the member to be fastened, and steel, stainless steel or the like is used.

  The die 20 has a short cylindrical large-diameter portion 24 and a cylindrical small-diameter portion 25 therebelow. The upper end portion of the large diameter portion 24 is a flat upper surface 21, and a concave portion for deforming the leg portion 12 of the self-piercing rivet 10 is formed in the central portion of the upper surface 21. The concave portion includes a circular bottom surface 22 at the center and a curved surface 23 around the bottom surface 22.

Fastened members 51, 52 are disposed on the upper surface 21 of the die 20, and the fastened members 51, 52 are pressed by the nose 27 from above. The head 11 of the self-piercing rivet 10 is placed inside the nose 27 and chucked.
The self-piercing rivet 10 is driven into the fastened members 51 and 52 by the punch 28. The leg tip 13 of the self-piercing rivet 10 penetrates the punch-side fastened member 51 and the receiving-side fastened member 52 adjacent to the die 20 does not penetrate but stays in it. The leg portion tip 13 of the leg portion 12 of the self-piercing rivet 10 is deformed by the die 20 so as to expand its diameter radially outward. The fastened members 51 and 52 are fastened to each other by the head 11 of the self-piercing rivet 10 and the leg portion 12 whose diameter is expanded in the fastened member 52.

FIG. 2 is an enlarged cross-sectional view of the joint after the fastened members 51 and 52 are fastened by the self-piercing rivet 10. When the fastened members 51 and 52 are arranged on the die 20 and pressed by the nose 27 and the self-piercing rivet 10 is driven by the punch 28, the leg portion 12 is fastened by the punch 28 on the punched fastened member 51. And the receiving-side fastened member 52 is plastically deformed. The receiving-side fastened member 52 is protruded downward by the legs 12, the protruding portion of the fastened member 52 is received in the recess of the die 20, and the lower surface of the fastened member 52 hits the bottom surface 22 of the recess. . When the fastened member 52 hits the bottom surface 22, it cannot move downward, so that the leg portion 12 of the self-piercing rivet 10 expands radially outward while pushing the fastened member 52 radially outward. Transforms into The leg tip 13 remains in the receiving member 52 adjacent to the die 20 without penetrating it.
The fastened members 51 and 52 are fastened to each other by the head 11 of the self-piercing rivet 10 and the leg portion 12 whose diameter is expanded in the fastened member 52. After being fastened by the self-piercing rivet 10, the nose 27 and the punch 28 move upward.

  The fastened member 52 is pushed radially outward by the enlarged leg portion 12. When the fastened member 52 is made of a hard material such as a high-tensile steel plate, the leg portion 12 of the self-piercing rivet 10 may not enter the fastened member 52 and may be abnormally deformed. Further, when the material is made of a material with poor spreadability, cracks are likely to occur near the curved surface 23 of the die 20.

  In the embodiment of the present invention, before the fastened members 51 and 52 are fastened, the self-drilling rivet 10 of the fastened member 52 to be fastened (a hard metal plate such as a high-tensile steel plate or a metal plate with poor spreadability) is used. The part to be fastened is tempered by energization heating using the energization heating device 2. The electric heating device 2 has an electrode structure attached to a tip holder portion of a resistance spot welder. Thereafter, using the self-piercing rivet fastening device 1, the fastened members 51 and 52 are fastened by the self-piercing rivet 10. Since the part to be fastened of the fastened member 52 is tempered, the end of the leg of the self-drilling rivet can enter and fasten the fastened members 51 and 52, and the fastened members 51 and 52 are cracked. Hateful.

In the following description, the receiving-side fastened member 52 made of a hard material is described as being tempered by energization heating. However, even when the fastened member 51 on the punch side is made of a hard material, the fastened member 51 can be tempered and softened by energization heating.
With reference to FIGS. 3-6, the structure of the electrode of the electric heating apparatus for carrying out electric heating to the to-be-fastened member by embodiment of this invention and tempering is demonstrated.

  FIG. 3 is a cross-sectional view of a portion where the fastened member 52 is sandwiched between the lower first electrode assembly 30a and the upper second electrode assembly 30b. The first electrode assembly 30a and the second electrode assembly 30b sandwich the left and right sides of the fastening portion 53 that heats the fastened member 52. The central portion of the sandwiched portion on both sides is a fastening portion 53 that conducts and heats. The fastening portion 53 is a portion that is tempered by heating and fastened by a self-piercing rivet.

The lower first electrode assembly 30a includes a first electrode member 31a made of a conductive material such as a metal material. The first electrode member 31a includes a first electrode base portion 32a, a first electrode contact portion 33a, and a first electrode cylindrical portion 34a. The first electrode base 32a has a rectangular parallelepiped shape having a certain length in the depth direction of FIG.
In the description of the embodiment of the present invention, the horizontal direction in FIG. 3 is referred to as the horizontal direction, the direction perpendicular to the plane in FIG. 3 is referred to as the depth direction, and the vertical direction is referred to as the height direction. One represents the right side and the other represents the left side.

A first electrode contact portion 33a extends upward from the right end portion of the first electrode base portion 32a. The length of the first electrode contact portion 33a in the depth direction in FIG. 3 is the same as that of the first electrode base portion 32a. The upper surface of the first electrode contact portion 33a is a flat surface and can contact the fastened member 52. The height from the upper surface of the first electrode base portion 32a to the upper surface of the first electrode contact portion 33a is h.
A cylindrical first electrode cylindrical portion 34a extends downward from the lower surface of the central portion of the first electrode base portion 32a. As will be described later, the first electrode cylindrical portion 34 a can be connected to the first chip holder connecting portion 47 a of the energization heating device 2.

  The lower first electrode assembly 30a has a first insulating chip 35a made of an insulating material. The first insulating chip 35a has a first insulating chip contact portion 36a and a first insulating chip fixing portion 37a. The first insulating chip contact portion 36a covers the left end portion of the upper surface of the first electrode base portion 32a, and the upper surface of the first insulating chip contact portion 36a is a flat surface, and can contact the fastened member 52. The first insulating chip fixing portion 37a covers the left end portion of the first electrode contact portion 33a.

The first insulating chip fixing part 37a is a part for fixing the first insulating chip 35a to the first electrode base part 32a. If the first insulating chip contact portion 36a can be fixed by another method, the first insulating chip fixing portion 37a may not be provided.
The width of the upper surface of the first insulating chip contact portion 36a that is in contact with the fastened member 52 is substantially equal to the width of the first electrode contact portion 33a. The length of the first insulating chip contact portion 36a in the depth direction in FIG. 3 is substantially equal to the length of the first electrode contact portion 33a in the depth direction.
The first insulating chip 35a may be made of a metal material. In this case, the first electrode member 31b is insulated with an insulating material such as an insulating sheet.

  The upper second electrode assembly 30b has the same parts and members as the lower first electrode assembly 30a and has the same shape. The first electrode assembly 30a on the lower side is attached upside down and upside down.

The first electrode contact portion 33a on the right side of the lower first electrode assembly 30a contacts the lower surface of the fastened member 52. The first insulating chip contact portion 36a of the left first insulating chip 35a contacts the lower surface of the fastened member 52.
The upper second electrode assembly 30b is attached to the lower first electrode assembly 30a opposite to the left and right. The second electrode contact portion 33b on the left side of the upper second electrode assembly 30b contacts the upper surface of the fastening member 52. The second insulating chip contact portion 36b of the right second insulating chip 35b contacts the upper surface of the fastened member 52. On the right side of the fastening portion 53, the fastened member 52 is sandwiched between the lower first electrode contact portion 33a and the upper second insulating chip contact portion 36b. On the left side of the fastening portion 53, the fastened member 52 is sandwiched between the lower first insulating chip contact portion 36a and the upper second electrode contact portion 33b.

As described above, in the energization heating device 2 according to the embodiment of the present invention, the lower first electrode assembly 30a and the upper second electrode assembly 30b are connected to the electrode contact portions 33a and 33b in contact with the fastened member 52. Indirect structure at different positions. A current flows between the lower electrode contact portion 33a of the fastened member 52 and the upper electrode contact portion 33b of the fastened member 52.
In the electric heating device 2, the second electrode contact portion 33b on the left side of the upper second electrode assembly 30b and the first electrode contact portion 33a on the right side of the lower first electrode assembly 30a are fastened. A current flows through the fastening portion 53 of the member 52. As a result, the fastening portion 53 is heated and tempered.

With reference to FIGS. 4-6, the structure of the 1st electrode assembly 30a and the 2nd electrode assembly 30b which hold down the to-be-fastened member 52 of the electric heating apparatus 2 is demonstrated in detail. The first electrode assembly 30a and the second electrode assembly 30b are the same. The second electrode assembly 30b is disposed upside down and horizontally opposite to the first electrode assembly 30a. 4-6, the 1st electrode assembly 30a is demonstrated. 4 is a top view of the first electrode assembly 30a of the embodiment of the present invention, FIG. 5 is a front view, and FIG. 6 is a right side view. The first electrode assembly 30a includes an insulating film 41, an insulating collar 42, and a bolt 43 in addition to the first electrode member 31a and the first insulating chip 35a.
However, when the insulating chip is made of an insulating material, the insulating film and the insulating collar may be omitted.

The first electrode member 31a has a rectangular parallelepiped first electrode base 32a. In the first electrode base 32a, two holes having female threads for screwing the bolts 43 are formed at the left end of FIG.
Please refer to FIG. A rectangular parallelepiped first electrode contact portion 33a extends upward from the right end portion of the first electrode base portion 32a. The height of the first electrode contact portion 33a is h. The upper surface of the first electrode contact portion 33a is a plane. The upper surface of the first electrode contact portion 33a can be brought into contact with the member to be fastened 52 so that a current can flow through the member to be fastened 52. A cylindrical first electrode cylindrical portion 34a extends downward from the central portion of the lower surface of the first electrode base portion 32a. The first electrode cylindrical portion 34 a is a portion connected to the first chip holder 46 a of the energization heating device 2.

A first insulating chip 35a is disposed on the left side of FIG. 5 of the first electrode base 32a. The first insulating chip 35a is an L-shaped member having a rectangular parallelepiped first insulating chip contact part 36a and a first insulating chip fixing part 37a extending in a direction perpendicular to the first insulating chip contact part 36a. . The first insulating chip contact portion 36a is located on the left side of the top surface of the first electrode base portion 32a in FIG. The height of the first insulating chip contact portion 36a is the same as the height of the first electrode contact portion 33a. The lateral length in which the first insulating chip contact portion 36a contacts the lower surface of the fastened member 52 is the same as the lateral length of the first electrode contact portion 33a.
The first insulating chip fixing portion 37a covers the left end portion of the first electrode base portion 32a. Two insertion holes are formed in the first insulating chip fixing portion 37a so as to allow the bolts 43 to pass therethrough.

The insulating film 41 is a thin film, and two holes for inserting the bolts 43 are formed. The insulating film 41 is disposed between the left end portion of the first electrode base portion 32a, the first insulating chip fixing portion 37a, the upper left side of the first electrode base portion 32a, and the first insulating chip contact portion 36a. .
The insulating collar 42 has a flange and a cylindrical portion extending from the flange. The flange of the insulating collar 42 abuts on the surface of the insertion hole of the first insulating tip 35a, and the cylindrical portion of the insulating collar 42 passes through the insertion hole of the first insulating chip 35a and enters the mounting hole of the first electrode base 32a. It has become.
The head of the bolt 43 contacts the flange of the insulating collar 42. The shaft portion of the bolt 43 can pass through the cylindrical portion of the insulating collar 42.

An insulating film 41 is sandwiched between the first electrode base 32a and the first insulating chip 35a. The head of the bolt 43 is received by the flange of the insulating collar 42. The shaft portion of the bolt 43 is inserted through the central hole of the insulating collar 42 inserted through the insertion hole of the first insulating chip fixing portion 37a, and is inserted through the mounting hole formed in the first electrode base portion 32a. The male screw of the bolt 43 is screwed into the female screw of the mounting hole of the first electrode base portion 32a. The first insulating chip 35a and the first electrode member 31a are assembled by the bolts 43 via the insulating film 41 and the insulating collar 42 to form the first electrode assembly 30a.
The first electrode contact portion 33a of the first electrode member 31a and the first insulating chip contact portion 36a of the first insulating chip 35a are substantially in the same plane, and can come into contact with the lower surface of the fastened member 52. Yes.

In one embodiment, the electrode length L shown in FIG. 4 is 24 mm, and the distance D between the first electrode contact portion 33a and the first insulating chip contact portion 36a is 24 mm. The height h of the first electrode contact portion 33a and the first insulating chip contact portion 36a is 4 mm.
The interval D is a lateral length between the first electrode contact portion 33a and the first insulating chip contact portion 36a of the first insulating chip 35a. As shown in FIG. 3, the right end of the second electrode contact portion 33b of the upper second electrode assembly 30b and the right end of the first insulating chip contact portion 36a of the lower first electrode assembly 30a Are aligned in the horizontal direction. Accordingly, the lateral distance between the right end portion of the second electrode contact portion 33b of the upper second electrode assembly 30b and the left end portion of the first electrode contact portion 33a of the lower first electrode assembly 30a. Is D.

Returning to FIG. 3, in the energization heating device 2 of the embodiment of the present invention, the two electrode assemblies 30 a, b are combined with the positions of the electrode contact portions 33 a, b and the insulating chips 35 a, b reversed left and right. On the left side of the fastening portion 53 in FIG. 3, the fastened member 52 is sandwiched between the electrode contact portion 33b of the upper second electrode assembly 30b and the first insulating chip contact portion 36a of the lower first electrode assembly 30a. . On the right side of the fastening portion 53, the fastened member 52 is sandwiched between the second insulating chip contact portion 36b of the upper second electrode assembly 30b and the first electrode contact portion 33a of the lower first electrode assembly 30a.
A current passing through the fastening portion 53 flows between the upper left second electrode contact portion 33b and the lower right first electrode contact portion 33a, and the fastening portion 53 of the fastened member 52 is electrically heated.

FIG. 7 is a schematic view of the vicinity of the electrode assemblies 30a and 30b of the energization heating device 2 according to the embodiment of the present invention. The electric heating device 2 is configured as an electric heating device 2 by attaching the electrode assemblies 30a and 30b of FIG. 3 to the tip holder portions 46a and 46b of a normal resistance spot welder via the tip holder connecting portions 47a and 47b. Yes.
The electric heating device 2 includes a lower first chip holder part 46a and an upper second chip holder part 46b. The first chip holder part 46a is fixed to the main body of the energization heating device 2, and the first chip holder connection part 47a at the tip of the first chip holder part 46a is the first electrode cylinder of the lower first electrode assembly 30a. It is fixed to the circular hole of the part 34a.

The upper second chip holder portion 46b can be moved up and down with respect to the main body of the energization heating device 2. The second tip holder connecting portion 47b of the second tip holder portion 46b is fixed to the circular hole of the second electrode cylindrical portion 34b of the second electrode assembly 30b. The second electrode assembly 30b can be moved up and down.
The second electrode assembly 30b is lowered, and the fastened member 52 can be sandwiched between the first electrode assembly 30a and the second electrode assembly 30b.

  Electric power can be supplied to the electrode members 31a, 31b from the power source 48 of the electric heating device 2 through the wiring 49. A switch Sa is provided in the wiring 49 going from the power source 48 to the lower first electrode member 31a. A switch Sb is provided in the wiring 49 going from the power supply 48 to the upper second electrode member 31b. When the switches Sa and Sb are closed, a current flows through the fastening portion 53 between the second electrode contact portion 33b of the second electrode member 31b and the first electrode contact portion 33a of the first electrode member 31a.

In the electric heating device 2 of the embodiment of the present invention, the first electrode assembly 30a is assembled to the lower first chip holder portion 46a of the electric heating device 2, and the second electrode assembly is attached to the upper second chip holder portion 46b. 30b is assembled. The second electrode assembly 30b is lowered, the fastened member 52 is sandwiched between the second electrode assembly 30b and the first electrode assembly 30a, and the current heating device is connected to the fastening portion 53 of the fastened member 52 via the electrode contact portions 33a and 33b. A current is passed from the second power source through the wiring 49, and the fastening portion 53 of the fastened member 52 is energized and heated. Thereby, the fastening part 53 of the to-be-fastened member 52 is heated, and tempering is performed.
When the energization heating is completed, the second electrode assembly 30b is moved upward and the fastened member 52 is removed. In the next step, the fastened members 51 and 52 are fastened by the self-piercing rivet 10.

Since the resistance spot welder is generally used in an automobile body production line such as a sheet metal welding process, the electrode assembly 30a, b can be attached to the resistance spot welder to provide the current heating device 2.
The heat treatment of the present invention can be performed by using an energization heating device 2 in which a resistance spot welding machine is modified in the vicinity of the self-piercing rivet fastening device 1 for fastening by a self-piercing rivet.

  The current and energization time required for tempering the fastening portion 53 of the fastened member 52 vary depending on the material and shape of the fastened member 52. If the fastening portion 53 is heated too much, it may be quenched and become brittle. Depending on the conditions of the fastened member 52, it is necessary to obtain the optimum current and energization time.

The dimensions of the electrode will be described. In one example, when joining with a self-piercing rivet 10 having a leg outer diameter of 3.4 mm, the electrode length L = 16 mm and the electrode spacing D = 12 mm are preferable. Alternatively, when joining with a self-drilling rivet 10 having a leg outer diameter of 5.3 m, both the electrode length L and the distance D are about 20 mm to 24 mm.
The current passed through the fastening portion 53 of the fastened steel plate 52 is 2 kA to 10 kA, and the time is about 0.5 to 7 seconds. These current and energization time conditions vary depending on conditions such as the material and shape of the fastened member 52 to be tempered.
After the energized heating device 2 is used to energize and heat the fastened member 52, it is cooled by natural air cooling. Thereafter, the self-piercing rivet fastening device 1 is used to fasten the fastening portion 53 that has been energized and heated of the fastened member 52 with the self-piercing rivet 10.

FIG. 8 shows the results of testing how the hardness of the fastened member 52 changes when energized while changing the dimensions, current, and energization time of the electrode structure.
In FIG. 8, a hot stamped steel plate having a hardness of Hv545 having a thickness of 1.2 mm is used as the member 52 to be fastened. The lengths L in the depth direction of the electrode members 31a and 31b were 24 mm and 20 mm. The distance D between the electrode contact portions 33a, b and the insulating chip contact portions 36a, b of the electrode assemblies 30a, b was 24 mm and 20 mm. (The length L and the distance D were the same length.) The currents passed between the electrode contact portions 33a and 33b were 3.5 kA and 4.5 kA. It was tested how the hardness of the fastened member 52 changes when testing with different energization times.

In FIG. 8, the point indicated by A is an electrode assembly having a hot stamped steel plate of hardness Hv545 having a thickness of 1.2 mm and a fastening member 52 of electrode length L = 24 mm and electrode spacing D = 24 mm. 30 was used. A current of 3.5 kA was applied for 0.7 seconds, and then natural air cooling was performed. As a result, the fastened member 52 was tempered to a hardness of about Hv290. When the fastened member 52 was fastened by the self-penetrating rivet 10, it was fastened normally.
If the member 52 to be fastened of the hot stamped steel plate is annealed to a hardness of about Hv290, it is considered that the member 52 to be fastened can be fastened by the self-piercing rivet.

When the self-piercing rivets 10 are fastened at a plurality of positions of the fastened members 51 and 52, the current heating is completed in a short time if the current can be heated to the positions of the plurality of fastening portions 53 in one step. FIG. 9 is a schematic view of an apparatus for energizing and heating a plurality of fastening portions 53.
Electrode assemblies 30a and 30b are arranged above and below the position of the fastening portion 53 of the fastened member 52. In FIG. 9, energization heating is performed at the four fastening portions 53 of the fastened member 52. The first electrode assemblies 30a are disposed at four locations below the fastened member 52. The second electrode assemblies 30b are arranged at four corresponding positions on the upper side of the fastened member 52.

A power supply 48 is provided. The power supply 48 is connected to the electrode assemblies 30a, b by wiring 49.
Switches Sa1 to Sa4 are provided in the wiring 49 below the lower first electrode assembly 30a. Switches Sb1 to Sb4 are provided on the wiring 49 on the upper second electrode assembly 30b.

The fastened members 52 are arranged between the upper four electrode assemblies 30a and b. First, the switches Sa1 and Sb1 are closed, and the leftmost fastening portion 53 is energized and heated. Next, the switches Sa1 and Sb1 are opened, the switches Sa2 and Sb2 are closed, and the second fastening portion 53 is energized and heated. Next, the switches Sa2 and Sb2 are opened, the switches Sa3 and Sb3 are closed, and the third fastening portion 53 is energized and heated.
In this way, the four fastening portions 53 are energized and heated in order.
If a plurality of locations as shown in FIG. 9 are energized and heated sequentially to the fastening portion 53, the plurality of fastening portions 53 can be energized and tempered sequentially with the fastened member 52 fixed. It is possible and efficient.

According to the embodiment of the present invention, the fastening portion 53 of the member to be fastened 52 can be partially heated by the current supplied between the electrode contact portions 33.
The fastened member 52 is heated to an appropriate temperature and tempered, the hardness is lowered, and the spreadability is increased. In the fastened member 52 that has been tempered, the load required to drive the self-piercing rivet is reduced. The self-piercing rivet is easy to pierce the fastened member 52 and easily advances through the fastened member 52.
Therefore, the self-piercing rivet cannot enter the fastened member 52, the tip of the leg can enter without buckling deformation, and the fastened member 51 and the fastened member 52 can be fastened, and the fastened member 52 is not easily broken. The self-piercing rivet 10 facilitates fastening.

  According to the embodiment of the present invention, the position of the fastening portion 53 to be heated of the fastened member 52 is determined by a jig, a robot, etc., and heated by energization, and the position of the fastening portion 53 is stored. When the heated fastening member 52 is fastened with a self-piercing rivet, the fastening members 51 and 52 to be fastened are overlapped, and the stored position of the fastening portion 53 is aligned with the position of the self-piercing rivet 10, and the fastening portion The self-piercing rivet 10 is driven into 53 and the fastened members 51 and 52 are fastened.

  The position of the fastening portion 53 in the fastened member 52 is determined, energized and heated, and then tempered.Then, in the step of fastening the fastened members 51 and 52 with the self-piercing rivet 10, the position of the fastening portion 53 heat-treated Can be adjusted to the position where the self-drilling rivet 10 is fastened. Therefore, alignment and position change can be easily performed.

  According to the embodiment of the present invention, only the minimum part necessary for fastening with the self-piercing rivet has to be tempered, so that the strength reduction of the entire vehicle body is small.

  Further, if the die-side fastened member 52 made of a high tension material is energized and heated, the punch-side fastened member 51 made of a resin material can also be fastened by the self-piercing rivet 10 with the fastened member 52. It is possible to reduce the weight of the car body.

1 Self-piercing rivet fastening device
2 Electric heating device
10 Self-drilling rivets
11 head
12 legs
13 Leg tip
20 dies
21 Top view
22 Bottom
23 Curved surface
24 Large diameter part
25 Small diameter part
27 Nose
28 Punch
30a, b first and second electrode assemblies
31a, b first and second electrode members
32a, b First and second electrode base
33a, b First and second electrode contact parts
34a, b 1st and 2nd electrode cylindrical part
35a, b first and second insulation chips
36a, b First and second insulating chip contact portions
37a, b First and second insulating chip fixing portions
41 Insulation film
42 Insulation collar
43 bolts
46a, b First and second tip holder
47a, b First and second tip holder connection
48 Power supply
49 Wiring
51 Fastened member (punch side)
52 Fastened member (receiving side)
53 Fastening part
Sa, b switch

Claims (4)

A first electrode member made of a conductive material having a first electrode base and a first electrode contact portion extending upward from one end of the first electrode base; the other of the first electrode base A first electrode assembly having a first insulating tip contact portion extending upward from an end portion, and comprising a first insulating tip insulated from the first electrode base;
A second electrode member made of a conductive material having a second electrode base and a second electrode contact portion extending downward from the other end of the second electrode base; and the second electrode base A second electrode assembly having a second insulating tip contact portion extending downward from one end portion, and comprising a second insulating tip insulated from the second electrode base portion;
The second insulating chip contact portion of the second electrode assembly is located above the first electrode contact portion of the first electrode assembly,
The second electrode contact portion of the second electrode assembly is located above the first insulating chip contact portion of the first electrode assembly,
At least one of the first electrode assembly and the second electrode assembly can move in a vertical direction,
A part of a member to be fastened is sandwiched between the first electrode contact portion and the second insulating chip contact portion, and between the first insulating chip contact portion and the second electrode contact portion, the An electrode structure in which a current can be passed through the fastened member between the first electrode contact portion and the second electrode contact portion with another part of the fastened member interposed therebetween. The electrode structure according to claim 1,
An electrode structure in which the first insulating chip and the second insulating chip are made of an insulating material. The electrode structure according to claim 1 or 2,
An electrode structure in which the first electrode assembly and the second electrode assembly have the same shape and are attached upside down and horizontally. An electric heating method for heating a fastening portion of a fastened member to be fastened by a self-piercing rivet using an electric heating device,
The energization heating device includes a first electrode assembly disposed below the fastened member, a second electrode assembly disposed above, a power source, wiring, and a switch,
The first electrode assembly includes a first electrode contact portion having a first electrode member made of a conductive material, a first insulating chip contact portion, and being insulated from the first electrode member. Consisting of an insulating chip,
The second electrode assembly includes the second electrode contact portion, and includes a second electrode member made of a conductive material, a second insulating chip contact portion, and is insulated from the second electrode member. Consisting of two insulating chips,
The first electrode contact portion and the second insulating chip contact portion are disposed to face each other,
The first insulating chip contact portion and the second electrode contact portion are disposed to face each other.
The electric heating method is
(a) The member to be fastened is arranged between the first electrode assembly and the second electrode assembly, and the position of the fastening portion is intermediate between the first electrode contact portion and the second electrode contact portion. To align
(b) sandwiching one side of the fastening portion of the fastened member between the first electrode contact portion of the first electrode assembly and the second insulating chip contact portion of the second electrode assembly;
(c) sandwiching the opposite side of the fastening portion between the first insulating chip contact portion of the first electrode assembly and the second electrode contact portion of the second electrode assembly;
(d) energization heating comprising a step of passing a current between the first electrode contact portion and the second electrode contact portion, energizing and heating the fastening portion, and tempering the fastening portion. Method.

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