JP2010188383A - Rivet joining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rivet joining method for excellently joining magnesium-made or magnesium alloy-made plates to be joined by self-pierce rivets, efficiently heating the joined part of the plates to be joined, and favorably holding (pressing) a part in the vicinity of joined parts of the plates. <P>SOLUTION: In the rivet joining method, one of a pair of plates 21, 22 to be joined by self-pierce rivets 10 is a Mg-made plate 21, and the compressive strain of the Mg-made plate 21 is 85%. In the rivet joining method, the joined part 25 to be joined with the self-pierce rivets 10 out of the Mg-made plate 21 is heated at the heating temperature of 280°C to the solidus line temperature (°C). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a rivet joining method in which a front side frame is provided in a longitudinal direction of a vehicle body, and a front pillar is provided at the rear of the front side frame and outside the vehicle body.

As a method for joining the plate materials to be joined, a pair of plate materials to be joined is joined (fastened) using a rivet (hereinafter referred to as “self-piercing rivet”) having a hollow leg on the head of the rivet. How to do is known.
According to this self-piercing rivet joining method, the joining plate materials made of magnesium or magnesium alloy are superposed by heating the joining plate materials using heating means such as a gas burner, an electric heater or a high frequency induction heater. Can be joined (fastened) to each other (for example, see Patent Document 1).

That is, according to the self-piercing rivet joining method of Patent Document 1, magnesium or magnesium alloy to-be-joined plate materials are superposed, a heating means is disposed in the vicinity of the joint portion of the superposed plate materials to be joined, and the arranged heating means The joined portion of the joined plate materials that are overlapped with each other is heated.
In this state, the head portion of the rivet can be pressed to push the leg portion into the joint portion (driving), and the tip end of the leg portion can be spread outward to join (fasten) the joint portion.

JP 2006-7266 A

  However, in the joining method of Patent Document 1, it is difficult to satisfactorily join the joined plate materials when the compressive strain of the joined plate materials made of magnesium or magnesium alloy joined by self-piercing rivets is 85%.

Moreover, according to the joining method of patent document 1, a heating means is arrange | positioned in the joint part vicinity of the overlapped to-be-joined board | plate material, and the joined part of the to-be-joined board | plate material overlapped with the arrange | positioned heating means is heated.
For this reason, the heat generated by the heating means is indirectly transmitted to the joint portion by air propagation, resulting in poor thermal efficiency, and it takes time to heat the joint portion, which hinders productivity.

  Furthermore, in the joining method of Patent Document 1, since the heating means is disposed in the vicinity of the joining portion, the heating means is in the way, and a pressing jig for sandwiching (pressing) the plate material to be joined is disposed in the vicinity of the joining portion. It is difficult.

  The present invention can satisfactorily bond with a self-piercing rivet when the bonded plate material made of magnesium or magnesium alloy bonded with a self-piercing rivet has a compression strain of 85%, and efficiently joins the bonded portion of the bonded plate material. It is an object of the present invention to provide a rivet joining method capable of heating and suitably holding (pressing) the vicinity of the joining portion of the joined plate materials.

  The invention according to claim 1 is a rivet joint in which one of the plate members to be bonded is a plate member made of magnesium or a magnesium alloy, and the compression strain of the plate member is 85%. The method is characterized in that, of the pair of plate members to be joined, a joining portion to be joined by the self-piercing rivet is heated to a heating temperature of 280 to a solidus line C.

  Claim 2 is a rivet joining method in which one of the joined plate members is a magnesium or magnesium alloy plate member among the pair of joined plate members joined by the self-piercing rivet, and the joining of the pair of joined plate members Sandwiching the periphery of the portion with a die and a punch, heating the joint with a die heating means embedded in the die and a punch heating means embedded in the punch, and the self-piercing rivet at the joint And a step of joining the joining portion with the self-piercing rivet by pushing in.

  According to a third aspect of the present invention, in the state where the joint is heated to 280 to solidus C. by the die heating unit and the punch heating unit, and the joint is joined by the self-piercing rivet, The compressive strain of the plate made of magnesium or the magnesium alloy is 85%.

  In the invention which concerns on Claim 1, when joining the to-be-joined board | plate material made from magnesium or a magnesium alloy with a self-piercing rivet, the junction part was heated to 280-solidus line degreeC. The ductility of the joint can be increased by heating the joint to 280 to solidus C.

Therefore, when the compressive strain of the joint becomes 85% in a state where the joint is joined with the self-piercing rivet, the ductility of the joint can be increased so as to cope with the compressive strain.
Thereby, it can prevent that a fracture | rupture (a crack, a crack) generate | occur | produces in a junction part, and can join a junction part favorably with a self-piercing rivet.

In the invention which concerns on Claim 2, the circumference | surroundings of the said junction part can be pinched | interposed with a die | dye and a punch among a pair of to-be-joined board | plate materials.
Therefore, the vicinity of the bonded portion of the bonded plate material can be suitably clamped (pressed).

Further, the joint can be heated by the die heating means embedded in the die and the punch heating means embedded in the punch.
Therefore, the heat generated by the die heating unit can be transmitted to the joint through the die, and the heat generated by the punch heating unit can be transmitted to the joint through the punch.
Thereby, the heat generated by the die heating means or the punch heating means can be efficiently transmitted to the joint portion, and the joint portion can be efficiently heated.

  As described above, the vicinity of the bonded portion of the bonded plate material can be suitably sandwiched (pressed), and the bonded portion can be efficiently heated so that the pair of bonded plate materials can be bonded well with the self-piercing rivet. Can do.

In the invention which concerns on Claim 3, a junction part was heated at 280-solidus line degree C with the die heating means and the punch heating means.
Thereby, even when the plate material made of magnesium or magnesium alloy has a compressive strain of 85%, the pair of plate materials to be bonded can be satisfactorily bonded by the self-piercing rivet.

It is sectional drawing which shows the self-piercing rivet and to-be-joined board | plate material used for the rivet joining method which concerns on this invention. It is sectional drawing which shows the state which joined the to-be-joined board | plate material with the rivet joining method which concerns on this invention. FIG. 3 is a three-part enlarged view of FIG. 2. It is a graph which shows the compressive strain of Mg board | plate material joined by the rivet joining method which concerns on this invention. It is a graph which shows the relationship between the compressive stress and compressive strain of Mg board | plate material. It is a graph about the relationship between the heating temperature of Mg board | plate material, and the compressive strain at the time of a fracture | rupture. It is sectional drawing which shows the self-piercing rivet joining apparatus used for the rivet joining method which concerns on this invention. (A) is a figure explaining the example which heats a junction part by the rivet joining method which concerns on this invention, (b) demonstrates the example which pushes in a self-piercing rivet into a junction part (driving) by the rivet joining method which concerns on this invention. FIG. It is a figure explaining the state which joined the Al board | plate material and the Mg board | plate material with the rivet joining method which concerns on this invention.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings.

The rivet joining method according to the embodiment will be described.
As shown in FIG. 1, the self-piercing rivet 10 is a member formed of chromium molybdenum steel (SCM435), and is provided on a head 11 formed on a substantially disk and a lower portion 11 a of the head 11. And a hollow leg 12.
The self-piercing rivet 10 is a self-drilling type rivet in which a pair of plate members 21 and 22 are joined by making holes in the pair of plate members 21 and 22 with hollow legs 12.

The leg portion 12 is formed in a cylindrical shape by the outer peripheral wall 13 and the inner peripheral wall 14, and the tip portion 15 is formed in a tapered shape in cross section by forming a portion on the inner peripheral wall 14 side of the tip portion 15 on the inclined surface 16. Has been.
The leg portion 12 is formed to have a height dimension H, an outer diameter D, and a thickness T1.

A pair of plate members 21 and 22 are joined by the self-piercing rivet 10.
Of the pair of plate members 21 and 22, one of the plate members 21 to be bonded is a magnesium alloy bonded plate member (hereinafter referred to as “Mg plate member”).
The other bonded plate material 22 is a bonded plate material made of aluminum alloy (hereinafter referred to as “Al plate material”).

As shown in the chemical composition of Table 1, the Mg plate material 21 has an Al component: 2.5 to 3.5%, a Zn component: 0.6 to 1.4%, and an Mn component: 0.2 to 1.0. %, Fe component: 0.005 or less, Si component: 0.10 or less, Cu component: 0.05 or less, Ni component: 0.005 or less, Ca component: 0.04 or less.
The Mg plate material 21 is a plate material having a plate thickness T2 (1.5 mm), a tensile strength of 230 to 280 MPa, and an elongation of 10 to 24%.

  The Al plate material 22 is A5182-O which is generally used, and is a plate material formed to a plate thickness T3 (1.6 mm), having a tensile strength of 290 MPa and an elongation of 16%.

As shown in FIG. 2, the self-piercing rivet 10 is pushed (driven) into the Mg plate material 21 and the Al plate material 22 in a state where the Al plate material 22 is superimposed on the Mg plate material 21.
As a result, the tip 15 of the self-piercing rivet 10 is spread outward in the radial direction of the leg 12, and the Mg plate 21 and the Al plate 22 are joined by the head 11 and the tip 15 (that is, the self-piercing rivet 10). Yes.

Here, when the Mg plate material 21 and the Al plate material 22 are joined by the self-piercing rivet 10, the Mg plate material 21 has a particularly large compressive strain ε in the compression range H.
The compressive strain ε [%] is obtained by the following equation.
Compression strain ε = [ΔT2 / T2] × 100 [%]
However,
ΔT2: Compression amount of the Mg plate material 21 T2: Plate thickness before compression of the Mg plate material 21 It is considered that a fracture (crack, crack) occurs from a portion where the compression strain ε is large.

Next, the compressive strain ε of the Mg plate material 21 will be described with reference to FIGS. 3 and 4. FIG. 4 shows the compression strain of the Mg plate material 21 on the vertical axis, the cross-sectional position of the Mg plate material 21 on the horizontal axis, and shows the relationship between the compression strains ε1 to ε10 and the cross-sectional positions P1 to P10 as a graph G1.
As shown in FIGS. 3 and 4, the Mg plate 21 has a compression strain ε1 of 3% at the site P1, a compression strain ε2 of the site P2 of 0%, and a compression strain ε3 of the site P3 of 45%.
Further, in the Mg plate material 21, the compressive strain ε4 of the portion P4 is 84 to 85%, the compressive strain ε5 of the portion P5 is 60%, and the compressive strain ε6 of the portion P6 is 67%.
Further, in the Mg plate material 21, the compressive strain ε7 of the portion P7 is 73%, the compressive strain ε8 of the portion P8 is 78%, the compressive strain ε9 of the portion P9 is 71%, and the compressive strain ε10 of the portion P10 is 60%.

As shown in FIG. 4, the Mg plate material 21 has the largest compressive strain ε4 of the portion P4 of 84 to 85%.
Therefore, when the compressive strain ε of the Mg plate material 21 is 84 to 85%, it is necessary to prevent the Mg plate material 21 from being broken.

In order to prevent the Mg plate material 21 from being broken, it is preferable to ensure a large ductility of the Mg plate material 21.
Here, a method of heating the Mg plate material 21 is known as means for ensuring a large ductility of the Mg plate material 21.

Next, the relationship between the heating condition of the Mg plate material 21 and the fracture will be described with reference to FIGS.
First, the relationship between the compressive stress and the compressive strain according to the heating conditions of the Mg plate material 21 will be described based on the graphs G2 to G7 in FIG. FIG. 5 shows the compressive stress [MPa] acting on the Mg plate material 21 on the vertical axis and the compressive strain [%] of the Mg plate material 21 on the horizontal axis.

In FIG. 5, a state where the Mg plate material 21 is heated at 100 ° C. is shown by a graph G2.
As shown in the graph G2, when the Mg plate material 21 was heated at 100 ° C., the Mg plate material 21 was compressed with a compressive stress of 360 MPa, and the compression strain ε was set to 40%.

A state where the Mg plate material 21 is heated at 120 ° C. is shown by a graph G3.
As shown in the graph G3, when the Mg plate material 21 was heated at 120 ° C., the Mg plate material 21 was compressed with a compressive stress of 390 MPa and the compression strain ε was set to 46%.

A state where the Mg plate material 21 is heated at 140 ° C. is shown by a graph G4.
As shown in the graph G4, when the Mg plate material 21 was heated at 140 ° C., the Mg plate material 21 was compressed with a compressive stress of 380 MPa, and when the compression strain ε was 53%, the Mg plate material 21 was broken.

A state where the Mg plate material 21 is heated at 160 ° C. is shown by a graph G5.
As shown by graph G5, when the Mg plate 21 was heated at 160 ° C., the Mg plate 21 was compressed with a compressive stress of 380 MPa, and the compression strain ε was set to 58%.

A state where the Mg plate material 21 is heated at 180 ° C. is shown by a graph G6.
As shown by graph G6, when the Mg plate material 21 was heated at 180 ° C., the Mg plate material 21 was compressed at a compressive stress of 370 MPa, and the compression strain ε was 62%.

A state where the Mg plate material 21 is heated at 200 ° C. is shown by a graph G7.
As shown by graph G7, when the Mg plate material 21 was heated at 200 ° C., the Mg plate material 21 was compressed with a compressive stress of 340 MPa, and the compression strain ε was 65%.

  Next, the relationship between the compressive strain ε and the heating temperature when a fracture occurs in the Mg plate material 21 will be described based on the graph G8 in FIG. FIG. 6 shows the compressive strain [%] at the time of fracture of the Mg plate 21 on the vertical axis and the heating temperature [° C.] of the Mg plate 21 on the horizontal axis.

As shown in FIG. 6, the compression strain ε: 40% when fracture occurs in the Mg plate 21 heated at 100 ° C. is plotted as d1 (marked in the graph).
The compressive strain ε: 46% when fracture occurs in the Mg plate 21 heated at 120 ° C. is plotted as d2.
The compressive strain ε: 53% when fracture occurs in the Mg plate material 21 heated at 140 ° C. is plotted as d3.

The compressive strain ε: 58% when fracture occurs in the Mg plate 21 heated at 160 ° C. is plotted as d4.
The compressive strain ε: 62% when fracture occurs in the Mg plate 21 heated at 180 ° C. is plotted as d5.
The compressive strain ε: 65% when fracture occurs in the Mg plate 21 heated at 200 ° C. is plotted as d6.

As shown in FIG. 6, since the plots d1 to d6 are located in the vicinity of the linear graph G8 (from the graph G8), the relationship between the compressive strain and the heating temperature when the Mg plate material 21 breaks is It turned out that it is in the direct proportional relationship shown by the graph G8.
Based on this graph G8, it was found that when the compressive strain ε of the Mg plate material 21 is 84 to 85%, heating exceeding 280 ° C. is necessary to prevent the Mg plate material 21 from breaking.

On the other hand, when the heating temperature of the Mg plate material 21 exceeds the temperature at which melting starts (solidus temperature), the heated Mg plate material 21 cannot maintain a solid state.
If the heated Mg plate material 21 is not maintained in a solid state, mechanical joining by the self-piercing rivet 10 becomes difficult.
Therefore, the heating temperature of the Mg plate material 21 is set to be equal to or lower than the temperature at which the Mg plate material 21 starts melting (solidus temperature).

  In this way, the Mg plate material 21, specifically, the joining portion 25 (Al joining portion 27 and Mg joining portion 26) shown in FIG. 9 is heated to 280 to solidus C ° by the die heating means 32 and the punch heating means 35. By heating, it is possible to prevent the breakage from occurring at the site P4 (see FIG. 3) of the Mg joint portion 26, and the Mg plate material 21 (joint portion 25) can be favorably joined with the self-piercing rivet 10.

Next, the self-piercing rivet joining apparatus 30 for heating the Mg plate material 21 to 280 to solidus C will be described with reference to FIG.
As shown in FIG. 7, the self-piercing rivet bonding apparatus 30 includes a die 31 that can abut on a bonding portion (hereinafter referred to as “Mg bonding portion”) 26 of the Mg plate material 21, and a die heating unit embedded in the die 31. 32, a punch 34 that can be brought into contact with a joint portion (hereinafter referred to as “Al joint portion”) 27 of the Al plate material 22, a punch heating means 35 embedded in the punch 34, and the self-piercing rivet 10 with the Mg joint portion 26. And a rivet pressing means (not shown) for pressing into the Al joint 27 (not shown).

The Mg joint portion 26 is, for example, a portion formed in a circular shape in plan view.
In addition, the Al joint portion 27 is, for example, a portion formed in a circular shape in plan view.

The die 31 is a member that can move in a direction orthogonal to the Mg plate material 21 (that is, in the direction of arrows AB).
The die 31 is formed so that the upper end portion 37 can come into contact with the Mg joint portion 26, a receiving recess 38 for receiving the Mg plate material 21 is formed at the center of the upper end portion 37, and a die storage space 39 for accommodating the die heating means 32. Is formed.
That is, the die 31 is formed so that the upper end portion 37 can come into contact with the outer periphery 26 a outer vicinity 26 b of the Mg joint portion 26 by forming the receiving recess 38 in the center of the upper end portion 37.

The die storage space 39 is formed at a position as close as possible to the Mg plate material 21.
By bringing the die storage space 39 close to the Mg plate material 21, the die heating means 32 is stored in a state of being close to the Mg plate material 21.
By bringing the die heating means 32 closer to the Mg plate material 21, the Mg bonding portion 26 and the Al bonding portion 27 (mainly the Mg bonding portion 26) can be efficiently heated by the die heating means 32.
As an example, the die heating means 32 uses an electric heater.

The punch 34 is a member that can move in a direction orthogonal to the Al plate material 22 (that is, in the direction of the arrow CD).
The punch 34 is formed so that the lower end 42 can come into contact with the outer periphery 27a of the Al joint 27 and the vicinity 27b of the outer periphery 27a, and a rivet storage space 43 for storing the self-piercing rivet 10 is formed at the center. A punch storage space 44 is formed.

The punch storage space 44 is formed at a position as close as possible to the Al plate material 22.
By bringing the punch storage space 44 close to the Al plate material 22, the punch heating means 35 is stored in a state of being close to the Al plate material 22.
By bringing the punch heating means 35 closer to the Al plate material 22, the Al bonding portion 27 and the Mg bonding portion 26 (mainly the Al bonding portion 27) can be efficiently heated by the punch heating means 35.
As the punch heating means 35, an electric heater is used as an example.

The self-piercing rivet 10 and the rivet pressing means are stored in the rivet storage space 43 of the punch 34.
The rivet pressing means is means for pressing (striking) the self-piercing rivet 10 into the Al joint 27 and the Mg joint 26 as indicated by an arrow by applying a pressing load F to the self-piercing rivet 10.
Hereinafter, “Mg joint portion 26 and Al joint portion 27” are collectively referred to as “joint portion 25”.

Next, a rivet joining method for joining the Al plate material 22 and the Mg plate material 21 with the self-piercing rivet 10 will be described with reference to FIGS.
As shown in FIG. 8A, an Al joint 27 is superimposed on the Mg joint 26, and an outer periphery 27a outer vicinity 27b of the Al joint 27 and an outer periphery 26a outer vicinity 26b of the Mg joint 26 are connected to a die 31 and a punch 34. And pinch with.
Therefore, the outer periphery 25a outer vicinity 25b (that is, the periphery of the joint portion 25) of the joint portion 25 can be suitably sandwiched (pressed).

In this state, the Mg bonding portion 26 and the Al bonding portion 27 (mainly the Mg bonding portion 26) are heated by the die heating means 32 embedded in the die 31.
Similarly, the punch heating means 35 embedded in the punch 34 heats the Al joint 27 and the Mg joint 26 (mainly the Al joint 27).
That is, the die heating unit 32 and the punch heating unit 35 heat the joint 25 to 280 to solidus C.

In this way, by heating the bonding portion 25 by the die heating means 32, the heat generated by the die heating means 32 can be transmitted to the bonding portion 25 via the die 31 without being indirectly transmitted by air propagation.
Further, by heating the joint 25 by the punch heating means 35, the heat generated by the punch heating means 35 can be transmitted to the joint 25 via the punch 34 without being indirectly transmitted by air propagation.
Thereby, the heat generated by the die heating means 32 and the punch heating means 35 can be efficiently transmitted to the joint portion 25, and the joint portion 25 can be efficiently heated.

  After heating the joint portion 25 to 280 to solidus C, a pressing load F is applied to the self-piercing rivet 10 by the rivet pressing means.

  As shown in FIG. 8 (b), by applying a pressing load F to the self-piercing rivet 10 by the rivet pressing means, the tip of the self-piercing rivet 10 (specifically, the tip of the leg 12) 15 It is pushed into (injected into) the joint 25 (Al joint 27 and Mg joint 26) as shown by an arrow E.

As shown in FIG. 9, the self-piercing rivet 10 is pushed into the joint portion 25 (the Al joint portion 27 and the Mg joint portion 26) by the rivet pressing means, so that the Mg joint portion 26 swells into the receiving recess 38.
In this state, the front end portion 15 of the self-piercing rivet 10 is spread outward in the radial direction of the leg portion 12.
Thereby, the joint portion 25 (the Al joint portion 27 and the Mg joint portion 26) is joined by the head portion 11 and the tip portion 15 of the self-piercing rivet 10 (that is, the self-piercing rivet 10).

  Thus, in a state where the joint portion 25 (Al joint portion 27 and Mg joint portion 26) is joined by the self-piercing rivet 10, as shown in FIG. 3, the Mg joint portion 26 has a compressive strain ε4: Compressed to 84-85%.

Here, the joint portion 25 (the Al joint portion 27 and the Mg joint portion 26) is heated to 280 to solidus C ° by the die heating means 32 and the punch heating means 35.
Thereby, in the site | part P4 of the Mg junction part 26, it can prevent that a fracture | rupture generate | occur | produces in the Mg board | plate material 21, and can join the junction part 25 with the self-piercing rivet 10 favorably.

  In addition, the outer periphery 25a outer vicinity 25b of the joining portion 25 can be suitably sandwiched by the die 31 and the punch 34, and the joining portion 25 is efficiently heated by the die heating means 32 or the punch heating means 35. The joint portion 25 can be further satisfactorily joined by the self-piercing rivet 10.

The rivet joining method according to the present invention is not limited to the above-described embodiments, and can be changed or improved as appropriate.
For example, in the above embodiment, the magnesium alloy plate material (Mg plate material) 21 is exemplified as one of the bonded plate materials. However, the present invention is not limited to this, and a magnesium plate material can also be used.

  Furthermore, the self-piercing rivet 10, the Mg plate material 21, the Al plate material 22, the joint portion 25, the outer periphery 25a of the joint portion, the outer peripheral vicinity 25b of the joint portion, the Mg joint portion 26, the Al joint portion 27, the self shown in the above embodiment. The shapes and configurations of the pierce rivet joining device 30, the die 31, the die heating unit 32, the punch 34, the punch heating unit 35, and the like are not limited to those illustrated, and can be appropriately changed.

  The present invention is suitable for application to an automobile in which a front side frame is provided in the longitudinal direction of the vehicle body and a front pillar is provided on the rear side outside the vehicle body of the front side frame.

  DESCRIPTION OF SYMBOLS 10 ... Self-piercing rivet, 21 ... Mg board | plate material (one to-be-joined board material among a pair of to-be-joined board materials), 22 ... Al board | plate material (the other to-be-joined board material among a pair of to-be-joined board materials), 25 ... Joining part, 25a ... outer periphery of the joint part, 25b ... near the outer periphery of the joint part, 26 ... Mg joint part, 27 ... Al joint part, 30 ... self-piercing rivet joining device, 31 ... die, 32 ... die heating means, 34 ... punch, 35 ... punch heating means.

Claims (3)

In a rivet joining method in which one of the joined plate materials is made of magnesium or a magnesium alloy, and the compressive strain of the plate material is 85% among the pair of joined plate materials joined by the self-piercing rivet.
A rivet joining method characterized by heating a joining part to be joined with the self-piercing rivet to a heating temperature of 280 to solidus line ° C among the pair of joined plates. In the rivet joining method in which one of the joined plates is made of magnesium or a magnesium alloy, among the pair of joined plates joined by the self-piercing rivet,
A step of sandwiching the periphery of the joint portion of the pair of joined plate materials with a die and a punch; and
Heating the joint with a die heating means embedded in the die and a punch heating means embedded in the punch; and
Joining the joint with the self-piercing rivet by pushing the self-piercing rivet into the joint; and
A rivet joining method characterized by comprising: The junction is heated to 280 to solidus C with the die heating means and the punch heating means,
3. The rivet joint according to claim 2, wherein a compression strain of the plate material made of magnesium or the magnesium alloy is 85% in the joint portion in a state where the joint portion is joined by the self-piercing rivet. Method.

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