JPH10142390A - Press forming jig of channel member for water channel and press forming method of the channel member using the jig - Google Patents

Abstract

PROBLEM TO BE SOLVED: To controllably bend a channel member for water channel when producing with bend forming by counting the spring back of zircalloy plate and disperse the stress at the bending part. SOLUTION: This jig is composed of a dice 2 having a recess part 5 nearly equal to the outline of a channel member (a) and an inversely tapered recess part 6 formed at its lower part, a rubberlike elastic body 3 with arc shape inserted in the recess part 5 and the inversely tapered recess part 6 and expanding at the middle of the upper surface 7 in the width direction, and a punch 1 on which the tip end lower surface 8 is formed in arc shape with a bump so as to coincide with the upper surface of the rubberlike elastic body 3 and a thin width part 10 thinning in the width direction above the tip end 9 formed similarly to the inner width of the channel member (a).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a BWR (boiling water type).
The present invention relates to a jig for producing a channel material constituting a water channel of a fuel assembly and a method for producing a channel material using the jig.

[0002]

2. Description of the Related Art A BWR fuel assembly used for high burnup, for example, has a large water channel 12 disposed at the center of a large number of fuel rods 11 as shown in FIG. It has a structure in which the upper nozzle 14 and the lower nozzle 15 are attached to the upper and lower portions, respectively, by being bundled by a plurality of spacers 13.

[0003] The water channel is shown in FIG.
As shown in (b), a square tube portion 16 made of Zircaloy and having a length of about 4 m, which forms the main body of the water channel 12, and upper and lower end plugs 17 and 17 attached to the upper and lower sides of the square tube portion 16, respectively. 18.

[0004] As shown in FIG.
It is manufactured by butting a pair of long channel members a having a U-shaped cross section so as to face each other, and welding the butted portion. The channel material is formed by cutting the Zircaloy plate for water channel into a narrow and fixed width, and then performing the two-stage press forming with a press brake or the like as shown in FIGS. b is formed in a U-shaped channel material a. In the figure, reference numeral 19 denotes a die, reference numeral 20 denotes a die positioning portion, and reference numeral 21 denotes a punch.

[0005]

However, in the above-mentioned conventional method of manufacturing a water channel, the channel material forming the rectangular tube portion is subjected to two-stage press forming, so that a primary bending step and a secondary bending step are performed. Variations occur in the abutment accuracy of positioning between the process and the process, which tends to cause variations in quality, such as dimensional changes, in the processed channel material, making it difficult to increase productivity and work efficiency during mass production. Was.

[0006] Zircaloy, which is the material of the water channel, is a difficult-to-process material such as a large springback (return after processing) after bending, and is used in a processing technique where it is difficult to achieve uniform bending accuracy. There was a problem. That is, when the bending process is performed in two steps as in the related art in manufacturing the channel material for the water channel by the bending process, strain stress concentration occurs in the bent portion (each bent portion), and the bending angle varies. In addition to the above, there has been a problem that it is difficult to secure dimensional accuracy, and that the stress is further emphasized due to a deep push in anticipation of springback.

According to the present invention, the channel material for the water channel is bent in a single step by using a jig having a novel structure, so that the channel material can be accurately distributed and stress at the time of bending can be dispersed. It is intended to manufacture efficiently in a state where it is placed.

[0008]

In other words, a press-molding jig for a channel material for a water channel according to the present invention, which meets the above-mentioned object, has a long U-shaped cross section that constitutes one half of a rectangular tube portion of a water channel. A long press-forming jig for forming a channel material from a flat plate material, wherein a zircaloy flat plate material cut to a predetermined dimension is positioned and placed, and the zircaloy flat plate material is positioned below a central portion in a width direction of the zircaloy flat plate material. A concave portion formed substantially the same width as the outer width of the channel material, and a reverse tapered concave portion formed continuously downward from a lower portion of the concave portion and having a reverse taper in the width direction and gradually expanding the skirt. A rubber-like elastic body that is inserted into these continuously formed recesses and reverse tapered recesses, and whose upper surface forms a circular arc whose central portion in the width direction swells, and whose lower surface at the tip portion is the upper surface of the rubber-like elastic material. It is formed so as to form a substantially concave arc, and the width of the distal end is formed to be substantially the same as the inner width of the channel material, and a narrow portion narrowing in the width direction is formed above the distal end. And a punch.

Further, a manufacturing method of the present invention is a method of forming the channel material for a water channel from a Zircaloy flat material using the jig of the present invention, wherein the Zircaloy flat material cut to a predetermined size is formed. The Zircaloy flat material is positioned and mounted on the die, and the bottom of the Zircaloy flat material expands in an arc shape by pressing the Zircaloy flat material into the concave portion of the die while pressing the center in the width direction against the rubber-like elastic body by the punch. While bending into a channel shape, the punch is further pushed into the reverse tapered recess of the die, and the upper surface of the rubber-like elastic body is expanded outward in the width direction between the side walls of the reverse tapered recess, thereby forming the channel-shaped portion. Press the bent part of the Zircaloy material to bend it further deeply, then pull out the punch and apply it to the springback of the Zircaloy flat material Ri bent back the folded portion, characterized in that obtaining the channel material.

[0010]

In the press-forming jig of the present invention and the forming method using this jig, the arc of the lower surface of the punch and the upper surface of the rubber-like elastic body and the pressing of the channel material into the inversely tapered recess of the die are performed. The bending is increased in anticipation of the springback. At this time, the angle of the bending can be adjusted by the pushing amount (depth) into the reverse tapered recess. Also, in this bending additional processing,
Since the rubber-like elastic body moves so as to expand outward in the width direction with respect to the pressing force of the punch, the pressing force of iron forming acts on the bent portion of the channel material, thereby distorting the strain stress of the bent portion. It is possible to increase bending while dispersing.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described.

FIG. 1 is a sectional view showing a press forming jig for a channel material for a water channel according to an embodiment of the present invention, and FIG. 2 is an overall view showing the forming jig and a press brake.
P is a press brake body in FIG. 2, N is NC control panel, K ₁ is the upper column, K ₂ is the lower column, F is shows s husband footswitch.

The press forming jig of the above embodiment is shown in FIGS.
As shown in FIG. 7, a long press forming jig for forming a long channel member a having a U-shaped cross section, which constitutes one half of a rectangular tube portion (not shown) of a water channel, from a Zircaloy flat plate member b. a tool, the punch 1 of the steel that is fixed to the upper column K _1, the die 2 made of steel that is fixed to the lower column K _2, rubber loaded in the die (or synthetic resin) elastic body 3 And is constituted by.

As shown in FIG. 1, the die 2 has a fitting recess 4 on which a Zircaloy flat plate b cut to a predetermined size is positioned and placed, and a central portion in the width direction of the Zircaloy flat plate b. A concave portion 5 having a rectangular section in a lower part formed at substantially the same width and substantially the same depth as the outer width of the channel material a;
An inverted tapered recess 6 is formed continuously from the lower part of the recess 5 downward, has a reverse taper θ in the width direction, and gradually expands the skirt. The shoulder of the recess 5 has one
A pair of steel rollers 5a are rotatably disposed.

As shown in FIG. 3, the rubber elastic body 3 has such a height as to be in contact with the Zircaloy flat plate material b placed in the fitting recess 4 and is opposite to the continuously formed recess 5. The upper surface 7 is fitted in the tapered recess 6 and is formed in an arc shape whose central portion in the width direction expands. The punch 1 has a tip lower surface 8 formed in a concave arc substantially matching the upper surface 7 of the rubber elastic body 3, and the width of the tip 9 is equal to the inner width of the channel material a. And a narrow portion 10 which is narrower in the width direction is formed above the front end portion 9. This narrow portion 10
Is formed to allow both sides of the bent channel material to escape when the channel material a is increased in bending. The molding dimension of the channel material a is mainly determined by the shape of the punch 1. On the other hand, using the above jig, a Zircaloy flat plate b
When the channel material a for water channel is formed from the above, the Zircaloy flat plate material b cut to a predetermined size as shown in FIG.

Next, as shown in FIGS. 4 and 5, the upper column of the press brake is lowered, so that the center of the Zircaloy plate b in the width direction is pressed against the rubber elastic body 3 by the punch 1 to form a die. By pushing the zircaloy flat plate b into the channel shape whose bottom swells in an arc shape by pushing it into the recess 5 of the second zigzag. Subsequently, as shown in FIG. 6, the punch 1 is further pushed into the reverse tapered recess 6 of the die 2, and the rubber elastic body upper surface 7 is expanded outward in the width direction between the side walls 6 a of the reverse tapered recess 6. As a result, the bent portion d of the channel-shaped zircaloy material c is pressed and squeezed to bend further.

Then, as shown in FIG.
And the bent portion d is bent back by the spring back of the Zircaloy plate material to obtain the channel material for the water channel. This “ironing” molding is performed by expanding the pressed rubber elastic body 3 outward in the width direction at the reverse tapered recess 6 after the bent portion d of the Zircaloy material c passes through the arrow B shown in FIG. The action of the punch 1 is gradually started, and the punching amount of the punch 1 is adjusted in anticipation of the springback amount of the Zircaloy material using the relief angle θ of the reverse taper (the bending portion increases as the pressing amount increases). Is bent deeply).

In the press-forming jig and the forming method according to the embodiment of the present invention, each of the arcs of the lower surface 8 of the punch and the upper surface 7 of the rubber elastic body and the pressing of the die 2 into the inversely tapered concave portion 6 allow the channel to be formed. The bending is increased in anticipation of the springback of the material. At this time, the angle of the bending can be adjusted by the amount of pushing of the punch 1 into the inverted tapered recessed portion 6. Since the rubber elastic body moves so as to expand outward in the width direction with respect to the pressing force of the punch in the reverse tapered concave portion, a force of uniform ironing acts on the bent portion d of the channel material, whereby the folding is performed. It is possible to disperse the strain stress of the curved part d. By performing the simultaneous two-point bending process from the conventional single-shot bending process, it is possible to reduce the number of processing steps and reduce the need for manual intervention in the processing, thereby improving safety.

[0019]

As described above, the press-forming jig and the forming method for a channel material for a water channel according to the present invention are characterized in that a Zircaloy flat plate is positioned and placed, and a center portion of the Zircaloy flat plate in the width direction. A concave portion formed to be approximately the same width as the outer width of the channel material, and an inverted taper formed continuously from the lower portion of the concave portion and having a reverse taper in the width direction and gradually expanding the skirt. A die having a tapered recess, a rubber-like elastic body which is inserted into the continuously formed recess and the reverse taper recess, and whose upper surface forms a circular arc whose central portion expands in the width direction; It is formed so as to form a concave arc substantially matching the upper surface of the body, and the width of the tip is formed to be substantially the same as the inner width of the channel material, and becomes narrower in the width direction above the tip. By using a punch having a part formed thereon, by pushing each arc of the punch lower surface and the rubber-like elastic body upper surface and the die into the inverse tapered recess, the bending is increased in anticipation of the springback of the channel material, The bending increase angle can be adjusted by the amount of pushing of the punch into the inverted tapered recess, and at the time of this bending increase processing, the rubber-like elastic body moves outward in the width direction with respect to the pressing force of the punch. Since it moves so as to expand, the force of the uniform ironing is applied to the bent portion of the channel material, thereby dispersing the strain stress in the bent portion, and producing a high-quality channel material accurately and once. Has a remarkable effect that it can be efficiently manufactured by bending.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a water channel press-forming jig according to an embodiment of the present invention.

FIG. 2 is an overall view showing the molding jig and a press brake.

FIG. 3 is a first process drawing of the molding jig.

FIG. 4 is a second process drawing of the same.

FIG. 5 is a third process diagram of the same.

FIG. 6 is a fourth process drawing of the same.

FIG. 7 is a fifth process diagram of the same.

FIG. 8 is a sectional view of a BWR fuel assembly.

FIG. 9A is a front view of a water channel. FIG. 2B is a cross-sectional view taken along line AA of FIG.

FIG. 10 is a perspective view showing a state of producing a water channel.

FIG. 11 is a first process drawing by a conventional press forming jig.

FIG. 12 is a second process drawing of the same.

FIG. 13 is a third process diagram of the same.

FIG. 14 is a fourth process diagram of the same.

FIG. 15 is a fifth process diagram of the same.

FIG. 16 is a sixth process drawing of the same.

[Explanation of symbols]

 Reference Signs List 1 punch 2 die 3 rubber elastic body 4 fitting concave portion 5 concave portion 5a roller 6 reverse taper concave portion 6a reverse taper side wall 7 elastic body upper surface 8 punch distal end lower surface 9 punch distal end portion 10 narrow width portion a channel material b zircaloy flat plate Material d Bend

Claims (2)

[Claims] 1. A long press-forming jig for forming a long channel material having a U-shaped cross section, which constitutes a half of a rectangular tube portion of a water channel, from a flat plate material, wherein the zircaloy is cut into a predetermined dimension. A flat plate is positioned and mounted thereon, and a recess formed below the center in the width direction of the Zircaloy flat and substantially the same width as the outer width of the channel material, and continuous downward from a lower portion of the recess. A die having a reverse taper recess which is formed in the width direction and has an inverse taper in the width direction, and gradually expands, and is inserted into these continuously formed recesses and the reverse taper recess, and the upper surface is centered in the width direction. A rubber-like elastic body having an arc bulging out, and a lower surface of the tip portion being formed in a concave arc substantially matching the upper surface of the rubber-like elastic material, and the width of the tip portion being the inner width of the channel material. Formed almost the same as And a punch formed with a narrow portion narrowed in the width direction above the front end portion. 2. A method for forming a channel material for a water channel from a Zircaloy flat material using the jig according to claim 1, wherein a Zircaloy flat material cut to a predetermined size is positioned and placed on the die. By pressing the central part in the width direction of the Zircaloy flat material into the concave portion of the die while pressing the Zircaloy flat material against the rubber-like elastic body by the punch, the Zircaloy flat material is bent into a channel shape whose bottom bulges in an arc shape, Further, the punch is pressed into the reverse tapered recess of the die, and the upper surface of the rubber-like elastic body is expanded outward in the width direction between the side walls of the reverse tapered recess, thereby pressing the bent portion of the channel-shaped zircaloy material. Bend further deeply, then pull out the punch and bend back the bent part by Zircaloy flat plate spring back A method for forming a channel material for a water channel, wherein the channel material is obtained by the above method.