JP5496774B2 - End plate molding method - Google Patents

Description

  The present invention relates to a bowl-shaped end plate that forms a closed hollow tank that is fixed to the both end portions of a cylindrical body portion that is open at both ends, and more specifically, is a contraction that is inserted into the body portion. An end plate having a diameter portion and a bulging portion having an outer diameter larger than the inner diameter of the barrel portion and abutting against an end surface of the barrel portion, and having the opening end portion, the reduced diameter portion and the bulge portion. The present invention relates to a method for forming a protruding portion.

  As the above-described end plate, one that constitutes a hot water storage tank for a water heater as disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-183963 is known.

  As shown in FIG. 4, the hot water storage tank 100 includes a cylindrical body portion 101 having both ends opened, and two end plates 102 and 102 respectively fixed to both opening portions of the body portion 101. Each of the end plates 102 and 102 has tapered diameter-reduced portions 102 a and 102 a inserted into the body portion 101 and an outer diameter larger than the inner diameter of the body portion 101, and comes into contact with the end surface of the body portion 101. Bulging portions 102b and 102b, the reduced diameter portions 102a and 102a are inserted into the barrel portion 101, and the bulging portions 102b and 102b are in contact with the end surfaces of the barrel portion 101, respectively. The contact portions 103 and 103 are joined by welding.

  As a method for forming the reduced diameter portion 102a and the bulging portion 102b of the end plate 102, a method by press working is conventionally known. As shown in FIG. 5, the molding method by press working includes a lower mold 110 having a concave portion 111 that matches the shape of the outer bottom surface of the bowl-shaped end plate 102, and the diameter is increased toward the opening. An upper die 115 having a tapered hole 116 having an inner diameter of the portion larger than the outer diameter of the opening of the end plate 102 before press processing is vertically opposed to each other, and the end plate 102 before the processing is disposed on the bottom side. The upper mold 115 is moved downward in this state and is moved downward, and the opening end of the end plate 102 is pushed by the inner peripheral surface thereof, which is indicated by a two-dot chain line in FIG. Thus, the reduced diameter portion 102a and the bulging portion 102b are formed by plastic deformation.

  4 and 5, the hatching of the cross section of the body 101 and the end plate 102 is omitted.

JP 2009-183963 A

  However, the above-described molding by the conventional press working has a problem that the degree of freedom at the opening end portion of the end plate 102 is high, and thus the bulging portion 102b to be molded varies in position from the outer bottom surface. This variation also occurs between a plurality of processed end plates 102, and even in a single end plate 102, the position of the bulging portion 102b from the outer bottom surface is different.

  For this reason, in the automatic welding process of a post process, the welding defect that welding of the contact part of the end surface of the trunk | drum 101 and the bulging part 102b cannot be performed frequently occurred. That is, as shown in FIG. 4, the automatic welding is performed in a standing state in which the upper and lower end plates 102 and 102 are fitted in the body 101, but as described above, the bulging portion 102 b from the outer bottom surface. If there is a variation in the position, the height position of the contact portion 103 between the end face of the body portion 101 and the bulging portion 102b changes. 103 and the welding position do not match, resulting in poor welding. Similarly, when the height position of the bulging portion 102b varies in one end plate 102, similarly, welding failure occurs at a location where the contact portion and the welding position do not match. And when such a welding defect arises, the basic function of the hot water storage tank in which high liquid-tightness is requested | required is not ensured.

  The present invention has been made in view of the above circumstances, and in the method of forming the reduced diameter portion and the bulging portion of the end plate, molding capable of forming the positional accuracy from the bottom of the bulging portion with high accuracy. The purpose is to provide a method.

The present invention for achieving the above object is a bowl-shaped end plate which is fixed to the both ends of a cylindrical body having both ends opened and constitutes a closed hollow tank,
The end plate having a reduced diameter portion inserted into the body portion and an bulging portion having an outer diameter larger than the inner diameter of the body portion and abutting against an end surface of the body portion at an opening end portion thereof. In the method of forming the reduced diameter portion and the bulging portion,
One end has a cylindrical shape, and the opening is placed in a mold in which the inner diameter of the opening is larger than that of the base, and the end face is in contact with the inner bottom surface of the mold. After the mold is inserted and held and the mold and the end plate are integrally rotated around the axis, the outer peripheral surface of the first pressing roller that can rotate about the axis is the opening end of the end plate. A first step of pressing against the inner peripheral surface, pressing the opening end of the end plate against the inner peripheral surface of the mold, and expanding the opening end into a tapered outer shape;
After the outer bottom surface of the end plate is pressed against the reference plane, the end plate is rotated about its axis, and the outer peripheral portion has a protrusion protruding outward in the circumferential direction, and the outer diameter is A die roller whose diameter is reduced in a taper shape from the ridge portion toward the end surface is arranged in the end plate after the diameter expansion so that the taper portion is located on the opening side of the end plate, and the end end of the end plate The position of the second pressing roller, which can be brought into contact with the inner peripheral surface of the unit and is separated from the reference surface by a predetermined distance, and then rotated about the shaft center is set to the opening of the end plate. The end plate is pressed against the outer peripheral surface of the end portion, the end portion of the end plate is pressed against the outer peripheral surface of the mold roller, and the second step of reducing the diameter of the open end portion into a tapered shape is sequentially performed. Related to the method.

  According to this invention, first, the first step is performed. That is, after the end plate is inserted into the mold and held in the mold, the end plate is rotated together with the mold. And in the state rotated in this way, the outer peripheral surface of a 1st press roller is pressed on the inner peripheral surface of the opening end part of an end plate, and the open end part of an end plate is pressed on the inner peripheral surface of a type | mold. Thus, the diameter of the opening end of the end plate is increased and the outer end is formed into a tapered shape.

  Next, in the second step, molding is performed to reduce the diameter of the enlarged diameter portion of the end plate after diameter expansion. That is, first, after pressing the outer bottom surface of the enlarged end plate against a predetermined reference surface, the end plate is rotated about its axis, and the mold roller is provided with a tapered portion on the opening side of the end plate. And positioned at a position that can contact the inner peripheral surface of the opening end portion of the end plate and is separated from the reference plane by a preset distance.

  Next, the outer peripheral surface of the second pressing roller that can rotate about the axis is pressed against the outer peripheral surface of the opening end of the end plate, and the opening end of the enlarged end plate is pressed against the outer peripheral surface of the mold roller. As a result, at the opening end of the end plate, a shape corresponding to the outer peripheral surface of the mold roller, that is, a bulging portion protruding outward along the circumferential direction, and a taper shape from the bulging portion toward the end surface. A reduced diameter portion having a reduced diameter is formed.

  As described above, according to the present invention, the bulge portion and the reduced diameter portion of the end plate are formed by the mold in the first step and the mold roller in the second step, so that the shape accuracy is extremely high. . Further, since the mold roller in the second step is positioned at a predetermined position with respect to the outer bottom surface of the end plate, the position of the bulging portion with respect to the outer bottom surface is made uniform among a plurality of end plates to be processed. At the same time, even in one end plate, the position of each part of the bulging part from the outer bottom surface can be made constant.

  Therefore, in the subsequent automatic welding process performed in the standing state in which the upper and lower end plates are fitted in the body part, the height position at which the body end face and the bulging part contact can be made constant, and the contact The part and the welding position can be matched. For this reason, even if it is automatic welding, the said contact part can be welded reliably and a highly liquid-tight tank can be manufactured.

  As described above, according to the present invention, the position of the bulging portion with respect to the outer bottom surface can be made uniform among a plurality of processed end plates, and even in a single end plate, The position on the basis of the outer bottom surface of each part of the bulging part can be made constant. Therefore, in the subsequent automatic welding process, the abutting portion between the barrel end face and the bulging portion can be reliably welded, and a highly liquid-tight tank can be manufactured.

It is explanatory drawing for demonstrating the content of the 1st process which concerns on one Embodiment of this invention, and is the top view which showed the principal part of the spinning machine for implementing the said 1st process. It is explanatory drawing for demonstrating the content of the 2nd process which concerns on this embodiment, and is the top view which showed the principal part of the spinning processing machine for implementing the said 2nd process. FIG. 3 is a front view of the spinning machine shown in FIG. 2. It is a front sectional view for explaining an endplate concerning the present invention. It is explanatory drawing for demonstrating the shaping | molding method of the conventional end plate.

  Hereinafter, a method for forming an end plate according to a preferred embodiment of the present invention will be described. The forming method according to the present embodiment includes a first step of expanding the diameter of the opening end of the bowl-shaped end plate K, and a second step of forming a bulging portion and a reduced diameter portion at the expanded opening end. It consists of. 1 shows a main part of the spinning machine for performing the first step, and FIG. 2 shows a main part of the spinning machine for performing the second step. Details of each step will be described below.

1. First Step As shown in FIG. 1, a spinning machine 1 for carrying out a first step includes a cylindrical mold 3 that is mounted coaxially to a main shaft 2 and a tailstock (not shown). ) And a pressing mechanism 15 mounted on a feed base (not shown).

  The mold 3 is open on the side opposite to the side on which the main shaft 2 is mounted. The inner diameter of the cylindrical inner peripheral surface 4 is slightly larger than the outer diameter of the end plate K, and the end plate K can be inserted smoothly. It is a size. Further, the inner end surface (inner bottom surface) is formed with a concave curved contact surface 5 that coincides with the outer bottom surface Ka with which the outer bottom surface Ka of the end plate K abuts. Further, a stealing hole is formed at the center of the inner end surface. 6 is formed. Further, the inner peripheral surface 4 of the opening end portion is formed with a diameter increasing portion 7 that increases in diameter toward the outer end surface in a tapered shape.

  The clamping mechanism 10 includes a flange 11 and a shaft portion 13 connected thereto, and the shaft portion 13 is supported by the tailstock (not shown) so as to be rotatable about the shaft center. The clamping mechanism 10 moves forward and backward with respect to the main shaft 2 by the operation of a tail shaft (not shown) fixed to the main shaft 2 and advanced and retracted relative to the main shaft 2. The front end surface 12 of the flange 11 is formed in a convex curved surface shape that matches the inner bottom surface Kb of the end plate K.

  The pressing mechanism 15 is capable of rotating the pressing roller 16 around its central axis via a abacus-shaped pressing roller (first pressing roller) 16, a support shaft 18 and a bearing fitted on the support shaft 18. And a fork-shaped holder 17 that is supported by the fork. The holder 17 is fixed to the feed base (not shown) so that the axis of the pressing roller 16 is located in a horizontal plane including the axis of the main shaft 2. The feed base (not shown) is driven in two orthogonal axes in a direction along the axis of the main shaft 2 and a direction (radial direction) perpendicular thereto. As shown in the figure, the pressing mechanism 15 is disposed so as to intersect the axis of the main shaft 2, and the protruding outer peripheral surface of the pressing roller 16 contacts the inner peripheral surface of the opening end of the end plate K. It is like that.

  Thus, in this first step, first, with the clamping mechanism 10 and the pressing mechanism 15 moved backward, the end plate K is positioned on the opening side of the mold 3 and the outer bottom surface Ka is It is inserted into the mold 3 so as to contact the contact surface 5 of the mold 3.

  Next, the clamping mechanism 10 is advanced, and the inner bottom surface Ka of the end plate K is pressed by the front end surface 12 of the flange 11, thereby holding the end plate K by the mold 3 and the flange 11. Then, the main shaft 2 is rotated with the end plate K sandwiched in this manner, and the mold 3 and the end plate K are rotated together with the main shaft 2. At that time, the clamping mechanism 10 pressing the end plate K also rotates.

  Next, the pressing mechanism 15 is advanced, and the pressing roller 16 is moved so that the protruding outer peripheral surface is located inside the boundary portion between the inner peripheral surface 4 and the enlarged diameter portion 7 of the mold 3, In FIG. 1, as indicated by the dashed line arrow, the pressing roller 16 is moved in the radial direction so that the protruding outer peripheral surface presses the inner peripheral surface of the opening end portion of the end plate K, and thereafter, by the pressing roller 16. The pressing roller 16 is moved in an oblique direction in which the movement toward the radially outer side and the backward movement are combined so that the pressing is maintained.

  As a result, the opening end of the end plate K is pressed against the diameter-enlarged portion 7 of the mold 3, and the diameter is increased in an outwardly expanding tapered shape following the diameter-enlarged portion 7. At this time, since the pressing roller 16 is rotatably supported, when it comes into contact with the inner peripheral surface of the end plate K, the pressing roller 16 itself rotates, thereby avoiding the sliding contact between the pressing roller 16 and the end plate K. Excessive load due to sliding friction is avoided.

  Next, after the pressing roller 16 presses the inner peripheral surface of the opening end portion of the end plate 3 to increase the diameter of the end portion and then moves away from the end plate K, the pressing mechanism 15 and the clamping mechanism 10 are retracted. Then, the rotation of the main shaft 2 is stopped and the rotation of the mold 3 and the end plate K is stopped. Then, after the rotation is stopped, the molded end plate K is removed from the mold 3.

  In the first step, as described above, the opening end portion of the end plate K is formed into a shape whose diameter is increased to an outwardly expanding taper shape.

2. 2nd process As shown in FIG.2 and FIG.3, the spinning processing machine 20 for implementing a 2nd process has the cylindrical holding member 25 with which the main axis | shaft 22 is mounted | worn with this, and the main axis | shaft 22. With the clamping mechanism 30 attached to a tailstock (not shown) moving back and forth along the axial direction, the pressing mechanism 45 attached to a first feed base (not shown), and the axis of the main shaft 22 as a boundary. A first support mechanism 35 disposed in the same area as the pressing mechanism 45, and a cutting mechanism 50 mounted on a second feed base (not shown) provided in an area opposite to the pressing mechanism 45. The second support mechanism 40 provided in the same region as the cutting mechanism 50 and the restraining mechanism 55 are provided.

  The holding member 25 is open on the side opposite to the side on which the main shaft 22 is mounted. The inner diameter of the cylindrical inner peripheral surface 26 is slightly larger than the outer diameter of the end plate K, and the end plate K is inserted smoothly. The size is possible. Further, a concavely curved contact surface 27 corresponding to the outer bottom surface Ka with which the outer bottom surface Ka of the end plate K abuts is formed on the inner end surface (inner bottom surface), and a stealing hole is formed at the center of the inner end surface. 28 is formed.

  The clamping mechanism 30 includes a flange 31 and a shaft portion 33 coupled thereto, and the shaft portion 33 is fixed to a tailstock shaft (not shown) supported by the tailstock (not shown). Then, the clamping mechanism 30 moves forward and backward with respect to the main shaft 2 by the forward and backward movement of the tailstock shaft (not shown). The flange 31 is rotatably mounted on the shaft portion 33 via a bearing 34, and the front end surface 32 thereof is formed in a convex curved surface shape that matches the inner bottom surface Kb of the end plate K. Thus, the clamping mechanism 50 moves forward with the advancement of a tailstock shaft (not shown), and the inner end face Kb of the end plate K inserted into the holding member 25 is moved to the front end face 32 of the flange 31. And the end plate K is clamped.

  The pressing mechanism 45 has a frustoconical shape, a pressing roller (second pressing roller) 46 having a protruding portion 46a protruding outward in the circumferential direction at a large diameter side end thereof, and a support shaft. 48 and a fork-shaped holder 47 that rotatably supports the pressing roller 46 on the axis thereof via a bearing externally fitted thereto. The holder 47 is located in a horizontal plane in which the axis of the pressing roller 46 includes the axis of the main shaft 22, and the protrusion 46 a that is parallel to the axis of the main shaft 22 and protrudes from the holder 47 is the axis of the main shaft 22. It is fixed to a first feed base (not shown) so as to be located on the side.

  The first feed base (not shown) is driven by an appropriate driving means in a biaxial direction perpendicular to the direction along the axis of the main shaft 22 in the horizontal plane and the direction (radial direction) perpendicular thereto. The pressing mechanism 45 moves with the first feed base (not shown), and the protrusion 46a of the end plate K inserted into the holding member 25 is movable in the horizontal plane. It can contact | abut to the opening end part outer peripheral surface.

  The first support mechanism 35 includes a protruding portion 36a that protrudes outward in the circumferential direction on the outer peripheral portion, and a reduced diameter portion whose outer diameter decreases in a taper shape from the protruding portion 36a toward one end surface. A mold roller 36 having 36b, and a fork-shaped holder 37 that rotatably supports the mold roller 36 about its axis through a support shaft 38 and a bearing fitted on the support shaft 38 are provided. The holder 37 has an end surface opposite to the reduced diameter portion 36b of the mold roller 36 facing the holding member 25, and the axis of the mold roller 36 is located in a horizontal plane including the axis of the main shaft 22, It is fixed to the outer peripheral surface of the shaft portion 33 so that it is parallel to the axis of the main shaft 22 and the mold roller 36 is positioned on the pressing mechanism 35 side.

  The cutting mechanism 50 has a truncated cone shape, and the cutter 51 is pivoted through a cutter 51 having a large-diameter edge as a cutting edge 51a, a support shaft 53, and a bearing fitted to the cutter 51. And a fork-shaped holder 52 that is rotatably supported. The holder 52 is positioned so that the axis of the cutter 51 is located in a horizontal plane including the axis of the main shaft 22, is parallel to the axis of the main shaft 22, and the cutter 51 is positioned on the axis side of the main shaft 22. It is fixed to a second feed base (not shown).

  Similarly, this second feed base (not shown) is also driven by an appropriate driving means in a biaxial direction orthogonal to the direction along the axis of the main shaft 22 in the horizontal plane and the direction (radial direction) perpendicular thereto. The cutting mechanism 50 moves together with the second feed base (not shown), and the cutting edge 51a of the cutter 51 is inserted into the holding member 25. The end plate K can be brought into contact with the outer peripheral surface of the opening end.

  The second support mechanism 40 includes a protruding portion 41a that protrudes outward along the circumferential direction on the outer peripheral portion, and a reduced diameter portion 41b that has an outer diameter that is tapered from the protruding portion 41a toward one end surface. And a fork-shaped holder 42 that rotatably supports the support roller 41 around the shaft center through a support shaft 43 and a bearing fitted on the support shaft 43. The holder 37 has an end surface opposite to the reduced diameter portion 41b of the support roller 41 facing the holding member 25, and the axis of the support roller 41 is located in a horizontal plane including the axis of the main shaft 22, The support roller 41 is fixed to the outer peripheral surface of the shaft portion 33 so as to be parallel to the axis of the main shaft 22 and to be positioned on the cutting mechanism 50 side.

  The shape of the outer peripheral surface of the support roller 41 is the same as the outer peripheral surface shape of the mold roller 36 except that the reduced diameter portion 41b is narrower than the reduced diameter portion 36b of the mold roller 36. Have. The support roller 41 and the mold roller 36 are arranged symmetrically about the axis of the main shaft 22.

  As shown in FIG. 3, the restraining mechanism 55 includes an arm 56 fixed to the shaft portion 33 so as to hang downward from the shaft portion 33, and a surface on the main shaft 22 side at the lower end portion of the arm 56. It consists of a pin 57 fixed so as to protrude from this and a restraining member 58 fixed on the base 29. As shown in FIG. 3, the pin 57 is formed on the restraining member 58 at a position where the clamping mechanism 50 advances toward the main shaft 22 and the front end surface 32 of the flange 31 contacts the inner end surface Kb of the end plate K. The shaft portion 33 is prevented from rotating about its axis by this engagement relationship.

  Thus, in the second step spinning machine 20 having the above-described configuration, the second step is performed as follows.

  That is, first, the end plate K that has completed the first step is positioned on the opening side of the holding member 25 and the outer bottom surface Ka abuts against the contact surface 27 of the holding member 25 in the same manner as in the first step. In such a manner, it is inserted into the holding member 25. At that time, the clamping mechanism 30, the first support mechanism 35 and the second support mechanism 40 supported by the holding mechanism 30, and the pressing mechanism 45 and the cutting mechanism 50 are all located in the retracted position.

  Next, the clamping mechanism 30 is advanced, and the end plate K is clamped with the holding member 25 by pressing the inner bottom surface Kb of the end plate K with the front end face 32 of the flange 31. At this time, the protrusion 36a of the mold roller 36 and the protrusion 41a of the support roller 41 are in contact with the inner peripheral surface of the enlarged diameter portion of the end plate K, respectively, and a pin 57 provided on the arm 56 of the restraining mechanism 55 is provided. The shaft member 33 is restrained from rotating by being inserted into the through hole 58a of the restraining member 58.

  Next, the main shaft 22 is rotated with the end plate K sandwiched in this manner, and the holding member 25 and the end plate K are rotated together with the main shaft 22. At this time, since the flange 31 pressing the end plate K is rotatably supported by the shaft portion 33, the flange 31 rotates together with the end plate K while the shaft portion 33 is stationary. The mold roller 36 and the support roller 41 are also rotated by the rotation of the end plate K, respectively.

  Next, the pressing mechanism 45 is moved forward so that the protruding portion 46a of the pressing roller 46 moves to a position facing the protruding portion 36a of the mold roller 36, and then the protruding portion 46a is an enlarged portion of the end plate K. The outer peripheral surface is moved in the radial direction so as to press, and then, while maintaining the pressing by the pressing roller 46, the pressing mechanism 45 is combined with the movement toward the inner side in the radial direction and the backward movement in the oblique direction. Move.

  As a result, the opening end of the end plate K is pressed against the protruding portion 36a and the reduced diameter portion 36b of the mold roller 36, and is shaped into a shape following the protruding portion 36a and the reduced diameter portion 36b. A corresponding bulging portion and a reduced diameter portion corresponding to the reduced diameter portion 36b are formed. At that time, since the pressing roller 46 is rotatably supported, the pressing roller 46 itself rotates when it comes into contact with the outer peripheral surface of the end plate K, thereby avoiding the sliding contact between the pressing roller 46 and the end plate K. Excessive load due to sliding friction does not act.

  Subsequently, after the pressing roller 46 presses and forms the outer peripheral surface of the enlarged diameter portion of the end plate 3 in this way, when the pressing roller 46 moves away from the end plate K, the pressing mechanism 45 is retracted to return to the original position. Let At the same time, the cutting mechanism 50 is advanced so that the cutter 51 is positioned outside the end plate K, and the cutting edge 51a is positioned so as to face the end surface 41c of the reduced diameter portion 41b of the support roller 41. Position it.

  Next, the cutting mechanism 50 is moved inward in the radial direction, and the opening tip of the end plate K is cut by the cutter 51. Thereafter, the cutting mechanism 50 is retracted backward to return to the original position, and then the clamping mechanism 30 is retracted to return to the original position, and the rotation of the main shaft 22 is stopped, and the holding member 25 and the end plate K are moved. Stop rotation. After the rotation is stopped, the molded end plate K is removed from the holding member 25.

  In the second step, the bulging portion and the reduced diameter portion are formed at the opening end portion of the end plate K as described above.

  As described in detail above, according to the molding method of this example, the bulging portion and the reduced diameter portion of the end plate K are molded into a shape that follows the shape of the mold 3 in the first step and the mold roller 36 in the second step. Therefore, the shape accuracy is extremely high. Further, since the mold roller 36 in the second step is positioned at a predetermined position with respect to the outer bottom surface Ka of the end plate K, the position of the bulging portion with respect to the outer bottom surface Ka is set between a plurality of processed end plates K. At the same time, even in one end plate K, the position of each part of the bulging portion from the outer bottom surface Ka can be made constant.

  Therefore, in a subsequent automatic welding process performed in a standing state in which the upper and lower end plates K are fitted in the body part, the height position where the body end face and the bulging part abut can be made constant. The contact portion and the welding position can be matched. For this reason, even if it is automatic welding, the said contact part can be welded reliably and a highly liquid-tight tank can be manufactured.

  In FIG. 1 to FIG. 3, the hatching of the cross section of the end plate K is omitted.

  As mentioned above, although one Embodiment of this invention was described, the specific aspect which this invention can take is not limited to this at all.

DESCRIPTION OF SYMBOLS 1 Spinning machine 2 Main shaft 3 type | mold 5 Contact surface 7 Expanded part 10 Nipping mechanism 11 Flange 15 Press mechanism 16 Press roller 20 Spinning machine 22 Main shaft 25 Holding member 27 Contact surface 30 Holding mechanism 31 Flange 35 First support mechanism 36 type Roller 36a Projection portion 36b Reduced diameter portion 40 Second support mechanism 41 Support roller 41a Projection portion 41b Reduced diameter portion 45 Press mechanism 46 Press roller 50 Cutting mechanism 51 Cutter 55 Stop mechanism

Claims (1)

It is a bowl-shaped end plate that is fixed to the both ends of the cylindrical body having both ends opened and constitutes a closed hollow tank,
The end plate having a reduced diameter portion inserted into the body portion and an bulging portion having an outer diameter larger than the inner diameter of the body portion and abutting against an end surface of the body portion at an opening end portion thereof. In the method of forming the reduced diameter portion and the bulging portion,
One end has a cylindrical shape, and the opening is placed in a mold in which the inner diameter of the opening is larger than that of the base, and the end face is in contact with the inner bottom surface of the mold. After the mold is inserted and held and the mold and the end plate are integrally rotated around the axis, the outer peripheral surface of the first pressing roller that can rotate about the axis is the opening end of the end plate. A first step of pressing against the inner peripheral surface, pressing the opening end of the end plate against the inner peripheral surface of the mold, and expanding the opening end into a tapered outer shape;
After the outer bottom surface of the end plate is pressed against the reference plane, the end plate is rotated about its axis, and the outer peripheral portion has a protrusion protruding outward in the circumferential direction, and the outer diameter is A die roller whose diameter is reduced in a taper shape from the ridge portion toward the end surface is arranged in the end plate after the diameter expansion so that the taper portion is located on the opening side of the end plate, and the end end of the end plate The position of the second pressing roller, which can be brought into contact with the inner peripheral surface of the unit and is separated from the reference surface by a predetermined distance, and then rotated about the shaft center is set to the opening of the end plate. The second step of pressing against the outer peripheral surface of the end portion, pressing the open end portion of the end plate against the outer peripheral surface of the mold roller, and reducing the diameter of the open end portion into a tapered shape is performed sequentially. End plate forming method.

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