JP3030641B1 - Different diameter joint and manufacturing method thereof - Google Patents

Abstract

To enable two raceways of different diameters to be connected in a straight line direction. SOLUTION: A large-diameter raceway mounting portion 20 that matches a large-diameter raceway and a small-diameter raceway mounting portion 30 that matches a small-diameter raceway are continuously provided in a linear direction, and a side plate of the small-diameter raceway mounting portion 30 is provided. Notch 33
Accommodates the extension piece 34 of the large-diameter raceway attachment section 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint for connecting two raceways having different diameters in a straight line.

[0002]

2. Description of the Related Art In a building such as a building, a factory or a station building, for example, as shown in FIG. 9, a raceway 2 is horizontally suspended and supported by a plurality of suspension supports 1 from a ceiling or an upper beam. A lighting fixture (not shown) and the like are fixed to the way 2, and an electric cable (not shown) is accommodated in the raceway 2 and wired. Since the length of one raceway is limited, the ends of the plurality of raceways 2 are connected and fixed to the junction box 4 and connected in a straight line or a right angle. (This kind of thing is called raceway, metal wire ぴ, metal duct, etc. depending on the size of the size,
Hereinafter collectively referred to as raceway)

As shown in FIG. 10, the junction box 4 has sockets 6, 6,... Of the same size having a U-shaped cross section attached from a rectangular box-shaped box body 5 having an open upper surface so as to protrude in all directions. The raceways 2, 2,... Having the same dimensions are attached to the sockets 6, 6,. Reference numeral 8 denotes a lid attached to the upper surface opening of the raceway 2.

[0004]

As described above, conventionally,
A plurality of raceways 2, 2,... Having the same dimensions are connected to the junction box 4, and an electric cable in a certain raceway 2 is branched and wired to another raceway 2 in the junction box 4 as necessary. .

[0005] Therefore, depending on the wiring situation, a raceway 2 in one direction may accommodate a large number of electric cables, while a raceway 2 in another direction may accommodate a small number of electric cables.

Therefore, it is advantageous to use a small-diameter (low-height) raceway for a raceway in which the number of electric cables accommodated is small because the cost is reduced and the weight is reduced.

However, since the plurality of sockets 6, 6,... In the junction box 4 are all for raceways having the same diameter, only the raceways having the same diameter can be connected to the junction box 4. For this reason, even when the electric cable is branched and only a small number of cables are accommodated, the same large-diameter raceway has to be used as shown in FIGS. 9 and 10, thereby increasing the cost.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem and to provide a joint having a different diameter which enables two raceways having different diameters to be connected at an arbitrary position in a linear direction, and a method of manufacturing the same. I have.

[0009]

In order to achieve the above object, a different diameter joint according to the present invention comprises a large diameter raceway mounting portion for mounting a large diameter raceway and a small diameter raceway for mounting a small diameter raceway. A first raceway mounting portion connected in a straight line direction, wherein the large-diameter raceway mounting portion is covered from outside by a bottom plate, both side plates, and a bent edge at an upper end of the large-diameter raceway; Bottom plate and the first
A first side plate perpendicular to each other standing vertically from both sides of the bottom plate, and a screw hole in the first bottom plate;
The small diameter raceway mounting portion is located at a position higher than the first bottom plate covered from the outside by a bottom plate, both side plates of the small diameter raceway, and a bent edge at an upper end of the both side plates.
A bottom plate and second side plates which are perpendicular to each other from both sides of the second bottom plate, and the second bottom plate has a screw hole, and the large-diameter raceway mounting portion has a large diameter. The large-diameter raceway mounting portion is inserted from the end of the large-diameter raceway so as to be covered from the outside by the raceway, and the screw screwed into the screw hole of the first bottom plate of the large-diameter raceway mounting portion. The bottom plate of the large-diameter raceway is pressed in a direction away from the first bottom plate of the large-diameter raceway attachment portion at the tip, and the bottom surface of the large-diameter raceway attachment portion is formed on the base inner surface of the bent edge of the large-diameter raceway. By pressing the upper ends of the two side plates, the end of the large-diameter raceway is fixed to the large-diameter raceway mounting portion. The small-diameter raceway mounting portion is inserted from the end of the small-diameter raceway so as to be covered, and the bottom plate of the small-diameter raceway is screwed into a screw hole of the second bottom plate of the small-diameter raceway mounting portion. By pressing in the direction away from the second bottom plate of the small-diameter raceway mounting portion to press the upper end portions of the second both side plates of the small-diameter raceway mounting portion against the base inner surface of the bent edge portion of the small-diameter raceway mounting portion. A different-diameter joint adapted to fix an end of a small-diameter raceway to the small-diameter raceway mounting portion, wherein the large-diameter raceway mounting portion and the small-diameter raceway mounting portion are integrated by bending a metal plate. A notch is provided at an upper corner of the second-side plate of the small-diameter raceway mounting portion on the large-diameter raceway mounting portion side; The extended pieces extended from the first side plates of the large-diameter raceway mounting portion to the upper portion are such that the upper end surfaces of the extended pieces and the upper end surfaces of the second side plates are substantially at the same height. It is characterized by being housed. Therefore, the large-diameter raceway and the small-diameter raceway can be easily connected at an arbitrary position in the linear direction.

[0010] Further, even if it is formed by bending one metal plate, the extension pieces extending from the first side plates of the socket mounting portion are formed on the second side plates of the raceway mounting portion. Since it is accommodated in the notch and the extension piece is inserted and fixed together with the second side plates inside the raceway,
Even if the weight of the raceway attached to the raceway attachment portion is received, deformation of the portion connecting the socket attachment portion and the raceway attachment portion can be prevented. In addition, different diameter joints can be easily manufactured by punching and bending a metal plate.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show different diameter joints 1 of the present invention.
0 illustrates one embodiment. The different diameter joint 10 is 2
A large-diameter raceway mounting portion 20 for mounting the large-diameter raceway 2 and a small-diameter raceway 2 'are for connecting the two different-diameter raceways 2, 2' in a linear direction. Diameter raceway mounting part 3 for
0 are continuously provided in the linear direction.

The large-diameter raceway 2 includes a bottom plate 2a and two side plates 2b and 2c parallel to each other so as to form a U-shaped cross section. The large-diameter raceway 2 is inclined downward (or horizontally) inward from the upper ends of the two side plates 2b and 2c. And bent edges 2d and 2e.

Similarly, the small-diameter raceway 2 'also has two side plates 2'b parallel to the bottom plate 2'a so as to form a U-shaped cross section.
2'c, and has bent edges 2'd, 2'e bent obliquely downward (or horizontally) inward from the upper ends of both side plates 2'b, 2'c. .

The large-diameter raceway 2 and the small-diameter raceway 2 'have the same bottom plates 2a, 2'a, but the side plates 2'b, 2'c of the small-diameter raceway 2' are the same as the large-diameter raceway 2. The height is smaller than the side plates 2b and 2c.

The large-diameter raceway mounting portion 20 is provided with a bottom plate 2a and both side plates 2b and 2c of the large-diameter (high) raceway 2 and a bent edge 2 at an upper end of the both side plates 2b and 2c.
Bottom plate 20 which is covered in conformity from the outside by d, 2e
a and first side plates 20b and 20c parallel to each other, and a screw hole 21 is provided in the first bottom plate 20a.

The small-diameter raceway mounting portion 30 is formed of a bottom plate 2'a and both side plates 2'b, 2'c of a small-diameter (low-height) raceway 2 ', and both side plates 2'b, 2'c. The second bottom plate 20a, which is higher than the first bottom plate 20a, which is covered from the outside by the bent edges 2'd, 2'e at the upper end in a conforming manner;
Bottom plate 30a and second parallel side plates 30b, 3b
0c and a screw hole 3 in the second bottom plate 30a.
1 and 31 (FIG. 3). The first side plate 20
The upper ends 20 'and 20' of the second side plates 30b and 30c are located at the same height.

The large-diameter raceway mounting portion 20 and the small-diameter raceway 30 are integrally formed by bending a flat metal plate, and the small-diameter race of the first bottom plate 20a of the large-diameter raceway mounting portion 20 is formed. Way attachment part 3
A vertical connecting plate 25 is continuously provided at an end on the zero side, and a second bottom plate 30a of the small-diameter raceway mounting portion 30 is continuously provided at an upper end of the connecting plate 25, and the second bottom plate 30a is They are parallel to each other at a position higher than the first bottom plate 20a by the height of the connection plate 25.

The second of the small-diameter raceway mounting portion 30 is as follows.
Notches 33, 33 are provided in the upper corners of the side plates 30b, 30c on the large-diameter mounting portion 20 side.

An extension piece extending from the outer end of the first side plates 20b, 20c of the large-diameter raceway mounting portion 20 on the side of the large-diameter raceway mounting portion 30 into the notches 33, 33. The upper end surfaces 34 'of the extension pieces 34, 34 and the upper end surfaces 30' of the second side plates 30b, 30c.
Are housed at the same height.

The first side plates 20b and 20c of the large-diameter raceway mounting portion 20 and the small-diameter raceway mounting portion 30
Tapered portions 22 and 32 are provided at the upper ends of the opposite end portions of the second side plates 30b and 30c so as to be easily inserted into the inside of the raceway.

The first bottom plate 20a of the large-diameter raceway attachment portion 20 has two screw holes 21 in the longitudinal direction.
21, a central hole 41 a of two recesses 41, 41 of a plastic protective base 40 having elasticity,
41a, the screws 42, 42 have their tips 42a,
42a is screwed into the screw holes 21 without projecting to the lower surface side of the bottom plate 20a.

Similarly, the second bottom plate 30a of the small-diameter raceway mounting portion 30 is provided with screw holes 31, 31 at two locations in the longitudinal direction, and is provided at two locations of an elastic plastic protection base 40. The screws 42, 42 are screwed into the screw holes 31, 31 with the tips 42a, 42a not protruding to the lower surface side of the bottom plate 30a, passing through the central holes 41a, 41a of the concave portions 41, 41.

Therefore, as shown in FIGS. 4 to 6, the large-diameter raceway 2 is inserted from the end into the large-diameter raceway 2 so that the large-diameter raceway mounting portion 20 is covered from the outside by the large-diameter raceway 2. The mounting portion 20 is inserted, and the screws 42, 42 screwed into the two screw holes 21, 21 of the first bottom plate 20a of the large-diameter raceway mounting portion 20 are rotated by a driver, and the tips 42a of the screws 42, 42 are rotated. , 42a, pressing the bottom plate 2a of the large-diameter raceway 2 in a direction away from the first bottom plate 20a of the large-diameter raceway mounting portion 20,
The first side plates 20 of the large-diameter raceway attaching portion 20 are provided on the inner surfaces of the bases of the bent edges 2d and 2e of the large-diameter raceway 2.
The ends of the large-diameter raceway 2 can be fixed to the large-diameter raceway mounting portion 20 by pressing the upper ends 20 ′, 20 ′ of the b, 20 c.

Similarly, the small-diameter raceway mounting portion 30 is inserted from the end into the small-diameter raceway 2 'so that the small-diameter raceway mounting portion 30 is covered from the outside by the small-diameter raceway 2'. Screws 42, 42 screwed into the two screw holes 31, 31 of the second bottom plate 30a of the mounting portion 30 are rotated by a screwdriver to
2 and 42, the bottom plate 2'a of the small-diameter raceway 2 'is pressed away from the second bottom plate 30a of the small-diameter raceway attachment portion 30 at the tip of the small-diameter raceway 2', and the bent edge 2'd of the small-diameter raceway 2 'is pressed. 2'e, the upper end 3 of the second side plates 30b, 30c of the small-diameter raceway mounting portion 30 on the inner surface of the base.
By pressing 0 'and 30', the end of the small-diameter raceway 2 'can be fixed to the small-diameter raceway mounting portion 30.

In mounting the small-diameter raceway 2 ', the second side plates 30 of the small-diameter raceway mounting portion 30 are attached.
b, 30c together with the extension pieces 34, 34 are located inside the side plates 2'b, 2'c of the small-diameter raceway 2 'and inside the bases of the bent edges 2'b, 2'c. Second side plate 3
0b, 30c and extension pieces 34, 3 '.
The upper ends 34 ', 34' of the 4 are pressed to fix the raceway 2 '.

For this reason, the small-diameter raceway mounting portion 30
Due to the weight of the small-diameter raceway 2 'fixed to the raceway 2 (and the electric cable housed in the raceway 2', the lighting equipment attached to the raceway 2 ', etc.), the second bottom plate 30a moves downward (FIG. 6). (In the clockwise direction), the extension pieces 34, 34 integrally connected to the first side plates 20b, 20c of the large-diameter raceway attachment portion 20 have a small diameter. Since this force is received by the inner surfaces of the bases of the bent edges 2'd and 2'e of the raceway 2 ', this deformation can be prevented.

It is to be noted that an arc-shaped protruding locking piece 34a is provided at the lower end of the extension piece 34, and a notch 33 is provided with a locking recess 33a for accommodating the locking protruding piece 34a. Even if the second side plates 30b and 30c try to move to the lower right by the force, the locking recess 3 of the notch 33
Since the locking projection 34a of the extension piece 34 is locked to the end of the large diameter raceway mounting portion 20 side 3a, deformation can be more reliably prevented.

Since the head of the screw 42 is located in the recess 41, an electric cable (not shown) is connected to the screw 4
No damage on the head. As described above, the large-diameter raceway 2 and the small-diameter raceway 2 ′ can be connected in a straight line by the different-diameter joint 10 of the present invention, so that the large-diameter raceway 2 is accommodated in the large-diameter raceway 2 connected to the junction box 4, for example. When the number of electric cables is small, the small-diameter raceway 2 'is connected to the large-diameter raceway 2 with the different-diameter joint 10 so that the size can be reduced and the cost can be reduced.

Next, a method of manufacturing the different-diameter joint 10 shown in FIGS. First, the metal flat plate 50 is punched into the shape shown in FIG. That is, rectangular first side plates 20b, 20c are continuously provided outside the rectangular first bottom plate 20a in the width direction, and the second bottom plate 30a side in the longitudinal direction of the first both plates 20b, 20c. Strip-shaped extension piece 3 from the outside end of
4 and 34 are connected to each other, and a rectangular connecting plate 2 is provided at an end of the first bottom plate 20a on the side of the extending pieces 34 and 34 in the longitudinal direction.
5 are connected to each other, and a rectangular second
Cutouts for accommodating the extension pieces 34, 34 at the outer corners of the rectangular first side plates 20b, 20c on both sides in the width direction of the second bottom plate 30a. The metal flat plate 50 is punched into a shape having the portions 33, 33 and the second side plates 30b, 30c having a smaller width in the width direction than the first side plates 30b, 30c.

In this punching process, tapered portions 22 and 32 are formed at the outer corners of the first side plates 20b and 20c and the second side plates 30b and 30c, respectively.

In this punching process, the extension piece 3
Engagement protruding pieces 34a protruding in an arc shape inside the tips of 4, 34
Notches 3 of the second side plates 30b, 30c
Locking recesses 33a, 33a for accommodating the locking protrusions 34a, 34a are provided in 3, 33. First bottom plate 20a
Then, screw holes 21 and 31 are formed in the second bottom plate 30a, respectively.

Next, the first bottom plate 20a and the first side plates 20
It is bent at right angles along the boundaries 51a and 51b of b and 20c. Also, the boundary line 5 between the first bottom plate 20a and the connecting plate 25
2a and bent at a right angle.
Is bent at right angles along the boundary line 52b with the bottom plate 30a in the direction opposite to the first bottom plate 20a.

Next, the second bottom plate 30a and the second side plates 3
0b, 30c are bent at right angles along the boundary lines 53a, 53b, so that the extending pieces 34, 34 become second side plates 30b,
The upper end surfaces 34 ', 34' of the extension pieces 34, 34 and the upper end surfaces 40 ', 40' of the second side plates 40b, 40c extend into the notches 33, 33 of the 30c so that they are substantially at the same height. The retaining pieces 34a, 34a of the pieces 34, 34 are accommodated so as to be located in the retaining recesses 33a, 33a of the notches 33, 33.

[0034]

As described above, according to the joint of the present invention, the large-diameter raceway mounting portion for mounting the large-diameter raceway and the small-diameter raceway mounting portion for mounting the small-diameter raceway are straight. A first bottom plate, wherein the large-diameter raceway mounting portion is externally covered by a bottom plate, both side plates of the large-diameter raceway, and a bent edge at an upper end of the both side plates; and the first bottom plate. The first bottom plate is provided with screw holes in the first bottom plate, and the small-diameter raceway mounting portion is provided with a bottom plate, both side plates of the small-diameter raceway, A second bottom plate located at a higher position than the first bottom plate which is covered from the outside by a bent edge at an upper end of both side plates, and second mutually parallel second sides vertically erected from both sides of the second bottom plate; A plate, and the A screw hole in a bottom plate of the large-diameter raceway, and the large-diameter raceway mounting portion is inserted from an end of the large-diameter raceway so that the large-diameter raceway mounting portion is covered from outside by the large-diameter raceway; The large-diameter raceway is pressed by pushing the bottom plate of the large-diameter raceway away from the first bottom plate of the large-diameter raceway mounting portion with the tip of a screw screwed into the screw hole of the first bottom plate of the way mounting portion. By pressing the upper ends of the first side plates of the large-diameter raceway mounting portion against the inner surface of the base of the bent edge portion, the end of the large-diameter raceway is fixed to the large-diameter raceway mounting portion. The small-diameter raceway mounting portion is inserted from the end of the small-diameter raceway so that the small-diameter raceway mounting portion is covered from the outside by the small-diameter raceway. The small-diameter raceway is bent by pressing the bottom plate of the small-diameter raceway in a direction away from the second bottom plate of the small-diameter raceway mounting portion with a tip end of a screw screwed into a screw hole of the second bottom plate of the way mounting portion. A different diameter splicer adapted to fix the end of the small diameter raceway to the small diameter raceway mounting part by pressing the upper end of the second side plate of the small diameter raceway mounting part against the inner surface of the base of the edge. Wherein the large-diameter raceway mounting portion and the small-diameter raceway mounting portion are integrally formed by bending a metal plate, and the large-diameter raceway mounting portion is mounted on second side plates of the small-diameter raceway mounting portion. A notch is provided at an upper corner portion of the portion, and an extension piece extending from the first both side plates of the large-diameter raceway attachment portion is provided at the notch at an upper end surface of the extension piece. Said It is characterized in that the upper end surfaces of the second side plates are housed so as to have substantially the same height. Therefore, the large-diameter raceway and the small-diameter raceway can be easily connected at an arbitrary position in the linear direction.

[0035] Even if the metal plate is formed by bending one metal plate, the extension pieces extending from the first side plates of the socket mounting portion are formed on the second side plates of the raceway mounting portion. Since it is accommodated in the notch and the extension piece is inserted and fixed together with the second side plates inside the raceway,
Even if the weight of the raceway attached to the raceway attachment portion is received, deformation of the portion connecting the socket attachment portion and the raceway attachment portion can be prevented. In addition, different diameter joints can be easily manufactured by punching and bending a metal plate.

[Brief description of the drawings]

FIG. 1 is a perspective view of an embodiment of the present invention.

FIG. 2 is a plan view of the embodiment.

FIG. 3 is a sectional view taken along line AA in FIG. 2;

FIG. 4 is a perspective view of a use state of the embodiment.

FIG. 5 is a plan view of the use state of the embodiment.

FIG. 6 is a sectional view taken along line BB in FIG. 5;

7 is a sectional view taken along the line CC in FIG. 6;

FIG. 8 is a view showing a punched shape of the metal plate of the embodiment.

FIG. 9 is an explanatory diagram showing a connection between a raceway and a junction box.

FIG. 10 is a sectional view showing a connection between a raceway and a junction box.

[Explanation of symbols]

 2 Raceway 2 'Raceway 4 Junction Box 10 Different Diameter Joint 20 Large Diameter Raceway Attachment 30 Small Diameter Raceway Attachment 33 Notch 34 Extension Piece 40 Protective Base 42 Screw

Claims (4)

(57) [Claims] 1. A large-diameter raceway mounting portion for mounting a large-diameter raceway and a small-diameter raceway mounting portion for mounting a small-diameter raceway are linearly connected. Are a bottom plate of the large-diameter raceway, both side plates, a first bottom plate which is covered from the outside by a bent edge at an upper end of the both side plates, and a first parallel bottom plate which is vertically erected from both sides of the first bottom plate. The first bottom plate has a screw hole, and the small-diameter raceway mounting portion is covered from outside by a bent plate at the bottom plate, both side plates, and upper ends of the small-diameter raceway. The second bottom plate located higher than the first bottom plate
A bottom plate and second side plates parallel to each other, which are vertically erected from both sides of the second bottom plate, and a screw hole is provided in the second bottom plate. The large-diameter raceway mounting portion is inserted from the end of the large-diameter raceway so as to be covered from the outside by the raceway, and the screw screwed into the screw hole of the first bottom plate of the large-diameter raceway mounting portion. The bottom plate of the large-diameter raceway is pressed in a direction away from the first bottom plate of the large-diameter raceway attachment portion at the tip, and the bottom surface of the large-diameter raceway attachment portion is formed on the base inner surface of the bent edge of the large-diameter raceway. 1, by pressing the upper ends of both side plates, the end of the large-diameter raceway is fixed to the large-diameter raceway mounting portion. The small-diameter raceway mounting portion is inserted from the end of the small-diameter raceway so as to be covered, and a bottom plate of the small-diameter raceway is screwed into a screw hole of the second bottom plate of the small-diameter raceway mounting portion. Is pressed in a direction away from the second bottom plate of the small-diameter raceway mounting portion to press the upper end portions of the second side plates of the small-diameter raceway mounting portion against the base inner surface of the bent edge portion of the small-diameter raceway mounting portion. A different diameter joint which is adapted to fix an end of a small-diameter raceway to the small-diameter raceway mounting portion, wherein the large-diameter raceway mounting portion and the small-diameter raceway mounting portion are formed by bending a metal plate. A notch is formed at an upper corner of the second side plate of the small-diameter raceway mounting portion on the large-diameter raceway mounting portion side. The extended pieces extended from the first side plates of the large-diameter raceway attaching portion to the large-diameter raceway mounting portion are such that the upper end surfaces of the extended pieces and the second side plates are substantially at the same height. A joint having a different diameter, which is accommodated in a housing. 2. A locking projection protruding downward is provided at a lower portion of a tip of the extension piece, and a locking recess in which the locking projection is housed in the notch of the second side plate. The joint having a different diameter according to claim 1 provided. 3. A large-diameter raceway mounting portion for mounting a large-diameter raceway and a small-diameter raceway mounting portion for mounting a small-diameter raceway are linearly connected to each other. Are a bottom plate of the large-diameter raceway, both side plates, a first bottom plate which is covered from the outside by a bent edge at an upper end of the both side plates, and a first parallel bottom plate which is vertically erected from both sides of the first bottom plate. The first bottom plate has a screw hole, and the small-diameter raceway mounting portion is covered from outside by a bent plate at the bottom plate, both side plates, and upper ends of the small-diameter raceway. The second bottom plate located higher than the first bottom plate
A bottom plate and second side plates parallel to each other, which are vertically erected from both sides of the second bottom plate, and a screw hole is provided in the second bottom plate. The large-diameter raceway mounting portion is inserted from the end of the large-diameter raceway so as to be covered from the outside by the raceway, and the screw screwed into the screw hole of the first bottom plate of the large-diameter raceway mounting portion. The bottom plate of the large-diameter raceway is pressed in a direction away from the first bottom plate of the large-diameter raceway attachment portion at the tip, and the bottom surface of the large-diameter raceway attachment portion is formed on the base inner surface of the bent edge of the large-diameter raceway. 1, by pressing the upper ends of both side plates, the end of the large-diameter raceway is fixed to the large-diameter raceway mounting portion. The small-diameter raceway mounting portion is inserted from the end of the small-diameter raceway so as to be covered, and the bottom plate of the small-diameter raceway is screwed into a screw hole of the second bottom plate of the small-diameter raceway mounting portion. Is pressed in a direction away from the second bottom plate of the small-diameter raceway mounting portion to press the upper end portions of the second side plates of the small-diameter raceway mounting portion against the base inner surface of the bent edge portion of the small-diameter raceway mounting portion. A method of manufacturing a joint of different diameters, wherein an end of a small-diameter raceway is fixed to the small-diameter raceway mounting portion, wherein the rectangular first bottom plate has a rectangular outer shape in a width direction. A first side plate is continuously provided, and the strip-shaped extending piece is continuously provided at an outer end of the first side plate on the second bottom plate side in a longitudinal direction, and the first bottom plate is provided with End of the extension side in the longitudinal direction A connecting plate having a rectangular shape is continuously provided, the second bottom plate having a rectangular shape is provided continuously at an end of the connecting plate, and the first first plate having a rectangular shape is provided outside a width direction of the second bottom plate. A step of punching a metal flat plate into a shape in which the second side plates having notches for accommodating the extension pieces are provided at outer corners on both side plate sides, and the connection with the first bottom plate. Bend along the board boundaries,
The first bottom plate and the second bottom plate are bent at the same angle in a direction opposite to the bending along a boundary line between the connection plate and the second bottom plate so that the first bottom plate and the second bottom plate are parallel to each other. 1 is bent at a right angle along a boundary line between both side plates, and is bent at a right angle along a boundary line between the second bottom plate and the second both side plates, so that the extending piece is the second side plate. A step of accommodating the extended piece and the upper end surfaces of the second side plates so that the upper end surfaces of the notched portions are substantially at the same height. 4. A locking projection projecting downward at a lower end of the extension piece, and a locking recess in which the locking projection is housed in the cutout portion of the second side plate. The method for manufacturing a different diameter joint according to claim 3, wherein the joint is provided.