KR20140092187A - Recycling stainless steel case for water purifier and method of manufacturing the same, and water purifier filter having the case - Google Patents

Abstract

A method for manufacturing a stainless steel case for a water purifier comprises: a case-molding step for molding a case having a thread-forming part at one side via a bulging process for molding a case by pressurizing a stainless steel pipe inserted into a die; a sealing surface forming step for forming a sealing surface via an entrance curing process for widening the surface area of the upper end of an entrance by winding the entrance at one side outward; a thread forming part expanding step for expanding the thread-forming part outward; a thread-forming step for forming a thread, which protrudes outward, on the thread-forming part using dice in the shape of a roller for pressurizing and rotating inward from the outside while rotating and supporting the expanded thread-forming part at an inner side; and a bottom forming step for forming a bottom by sealing a side facing the entrance of the case. The present invention can reduce production costs greatly as a product with desired specification (inner pressure: 20kg/cm^2, destruction pressure: 38kg/cm^2) can be manufactured using a raw material (STS 304) of a foil with thickness of 0.3 to 0.6 t in manufacturing a stainless steel case by molding a case via bulging process.

Description

TECHNICAL FIELD The present invention relates to a recycling stainless steel case for a water purifier, a manufacturing method thereof, and a filter for a water purifier having the water purifier,

The present invention relates to a filter for a water purifier, more specifically, a case itself can be disassembled and assembled so that the case can be disassembled, washed and reused, thereby remarkably reducing the maintenance cost of the water purifier and reducing environmental pollution To a recycling stainless steel case for a water purifier, a manufacturing method thereof, and a filter for a water purifier having the same.

As the distrust of tap water increases due to environmental pollution, the use of water purifier is gradually spreading. A water purifier is a device for filtering natural water (hereinafter referred to as "raw water") such as tap water or weak water, and by passing raw water through various kinds of filtering means, it removes foreign substances or harmful substances contained in raw water, Is provided.

Various types of water purifiers are used, and reverse osmosis water purifiers are representative ones. The reverse osmosis type water purifier purifies raw water by using a so-called reverse osmosis filter (hereinafter referred to as "membrane filter"), and the membrane filter is formed of a plurality of pores having very small diameters to remove foreign matter and harmful substances.

1 is a sectional view of a general filter for a water purifier according to the prior art. As shown in FIG. 1, a conventional filter for a water purifier 100 includes a case 110 having an internal space of a predetermined size, a filter 110 installed inside the case 110 for filtering foreign substances or harmful substances contained in the raw water, A filter filler 120 and a cap 130 which is bonded to one side of the case 110 so as to seal the case 110 and places the filter filler 120 inside the case 110. A method of joining the stopper 130 to one side of the case 110 is to rotate the stopper 130 at a high speed in a state where the stopper 130 is attached to the case 110 so that the assembled parts are melted and fused together And a method in which a chemical substance is injected into a gap in a gapped region and fused to each other by the chemical substance.

However, since the fusing method can not separate the plug 130 from the case 110, the filter for the water purifier 100 itself must be disposed of after being used for a predetermined period of time and replaced with a new filter for the water purifier. On the other hand, the filter for a water purifier has a replacement cycle of 3 to 6 months in short or an exchange cycle of 18 to 24 months in a long period, depending on the application.

As described above, since the conventional filters for water purifiers are generally manufactured as disposable consumables, the manufacturing cost of the case is as low as about 1,500 to 2,000 won. However, since the entire case including the filter filler material should be discarded after a certain use time has elapsed, serious waste of resources is caused, and environmental pollution is caused by discarded filters.

As a technique for improving these problems, Korean Utility Model Publication No. 1998-034319 discloses a screw fastening method in which a case and a cap can be disassembled and assembled, and only the filter filler inside the case is replaced at regular intervals, There is disclosed a filter case structure for reusing a filter. In addition, Korean Patent Registration No. 10-0303180 discloses a screw fastening method in which a case and a cap can be disassembled and assembled. In addition, a filter filler is made of stainless steel, and the case, the plug and the filter filler are disassembled and cleaned at regular intervals And a filter device for a water purifier for re-assembly and re-use.

However, most of the products currently in circulation, including the above-described conventional technology, manufacture a case that can be disassembled and assembled into a plastic material. In the case of the recycling filter in which the filter material is replaced with the plastic material, there is a problem that the manufacturing cost of the case is four to five times higher than the manufacturing cost of the case used in the conventional disposable filter.

On the other hand, some products are manufactured so that the case can be disassembled and assembled using stainless steel. In the case of such a stainless steel case, one side of a cylindrical stainless steel pipe having a certain thickness is CNC lathe formed to form a thread for disassembly and assembly with a cap, and the other side is brazed or argon welded with a stainless steel plate to manufacture a case. However, in order to form a thread for the disassembly and assembly of a CNC lathe, it is necessary to use a stainless steel pipe having a thickness of about 1.2 mm (1.2t). The manufacturing cost of the stainless steel case using the thick stainless steel pipe is 10 times higher than the manufacturing cost of the case used in the conventional disposable filter, which causes a problem of mass production and low marketability.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide a water purifier which can be disassembled and assembled, And to provide a recycling stainless steel case for a water purifier that can reduce environmental pollution, a manufacturing method thereof, and a filter for a water purifier having the same.

The present invention also relates to a method for manufacturing a stainless steel case, which comprises forming a stainless steel case through a bulging process, producing a product of a desired specification even when using a raw material for a thin plate having a thin thickness, Another object of the present invention is to provide a case, a manufacturing method thereof, and a filter for a water purifier having the same.

According to another aspect of the present invention, there is provided a method of manufacturing a recycled stainless steel case for a water purifier, comprising the steps of: forming a stainless steel pipe inserted in a mold through a bulging process, A sealing surface forming step of forming a sealing surface through an inlet portion curling process in which the inlet portion of one side is rounded outward to widen the surface area of the top portion of the inlet portion; And a roller-shaped mold for pressing and rotating the expanded screw-forming portion from the inside to the inside and rotating the screw-formed portion in an outward direction. A thread forming step of forming a thread, and a side opposite to an inlet part of the case, And forming a bottom portion by closing the bottom portion forming step.

According to another aspect of the present invention, there is provided a method of manufacturing a recycled stainless steel case for a water purifier, comprising the steps of: forming a casing having a thread forming portion on one side thereof through a bulging process for forming a pressure on a stainless steel pipe inserted in a mold; A step of expanding the thread forming part in an outward direction, a step of expanding the thread forming part in an outward direction, a step of expanding the thread forming part in the thread forming part by using roller type molds rotating and supporting the expanded thread forming part from the inside, A sealing surface forming step of forming a sealing surface through an inlet portion curling process in which the inlet portion of one side is rounded outward and the surface area of the top portion of the inlet portion is widened; And a bottom portion is formed by sealing the side facing the inlet portion of the case And a bottom forming step.

According to another aspect of the present invention, there is provided a method of manufacturing a recycled stainless steel case for a water purifier, comprising the steps of: forming a case having a thread forming portion on both sides through a bulging process for forming a pressure on a stainless steel pipe inserted in a mold; Forming step and a sealing step for forming respective sealing surfaces through an inlet part and an outlet part curing step of widening the surface area of the inlet part and the outlet part respectively by rounding the inlet part and the outlet part on both sides in the outward direction, Forming a threaded portion by expanding the threaded portion to expand the threaded portion in the outward direction, and forming the threaded portion by roller-shaped dies that rotate and support the expanded threaded portion inwardly from the inside, Forming a thread-forming step for forming respective threads protruding outward in the part And it characterized in that.

According to another aspect of the present invention, there is provided a method of manufacturing a recycled stainless steel case for a water purifier, comprising the steps of: forming a case having a thread forming portion on both sides through a bulging process for forming a pressure on a stainless steel pipe inserted in a mold; A screw-forming portion expanding step of expanding the screw-forming portion in the outward direction, a screw-forming portion expanding step of screwing the expanded screw-forming portion in the inner direction, And an inlet portion and an outlet portion curling each of which rounds the inlet portion and the outlet portion on both sides in the outward direction to widen the surface area of the inlet portion and the outlet portion, respectively, Curing process to form each sealing surface. And it characterized in that.

In order to achieve the above object, the recycled stainless steel case for a water purifier according to the present invention is characterized in that it is manufactured by the manufacturing method as described above.

In order to attain the above object, the filter for purifying water of the present invention is characterized by including a recycled stainless steel case for a purifier manufactured by the above-described manufacturing method.

According to the present invention, since the case itself can be disassembled and assembled, the case can be disassembled, washed and reused, thereby remarkably reducing the maintenance cost of the water purifier and reducing environmental pollution.

Further, this invention is desired specifications even with the raw material (STS 304) of the thin plate, the thickness 0.3t ~ 0.6t as molded over the bulging step in preparing a stainless steel case (pressure: 20Kg / cm ^2, breaking Pressure: 38 Kg / cm ² ) can be manufactured, which is advantageous in that the manufacturing cost can be remarkably reduced.

In addition, according to the present invention, since the thread of the stainless steel case which is disassembled and assembled with the stopper is formed by the rolling method using the roller type mold, the height and width of the screw thread can be made large and the fastening force with the stopper is greatly improved have.

In addition, according to the present invention, since the bottom of the stainless steel case is formed by using a dish-type hard plate, the case is prevented from being deformed, and if it is subjected to excessive pressure, it is deformed before the case ruptures, There is an advantage that the problem of the case can be easily grasped.

1 is a sectional view of a general filter for a water purifier according to the prior art,
2 is an exploded cross-sectional view showing a configuration of a filter for a water purifier having a recycled stainless steel case for a water purifier according to the first embodiment of the present invention,
Fig. 3 is an engaging sectional view of the filter for purifier shown in Fig. 2,
FIG. 4 is a flowchart illustrating a manufacturing process of the recycled stainless steel case for a water purifier shown in FIG. 2,
FIG. 5 is a front view comparing the steady state and the abnormal state of the recycled stainless steel case for a water purifier shown in FIG. 2,
6 is an exploded cross-sectional view showing a configuration of a filter for a water purifier having a recycled stainless steel case for a water purifier according to a second embodiment of the present invention,
Fig. 7 is an assembled cross-sectional view of the filter for purifier shown in Fig. 6,
8 is a flowchart illustrating a manufacturing process of the recycled stainless steel case for a water purifier shown in FIG.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments of a recycled stainless steel case for a water purifier according to the present invention, a method for manufacturing the same, and a filter for a water purifier having the same will be described in detail with reference to the accompanying drawings.

≪ Embodiment 1 >

FIG. 2 is an exploded cross-sectional view showing a constitutional relationship of a filter for a water purifier having a recycled stainless steel case for a water purifier according to the first embodiment of the present invention, and FIG. 3 is an end view of the water purifier filter shown in FIG.

2 and 3, a filter 200 for a water purifier according to this embodiment includes a stainless steel case 210 having an internal space of a predetermined size, and a stainless steel case 210 installed inside the stainless steel case 210, A filter filler 220 for filtering foreign substances or harmful substances contained in the stainless steel case 210 and a stopper 220 which is coupled to one side of the stainless steel case 210 so as to seal the stainless steel case 210, And a sealing packing 240 inserted between the stainless steel case 210 and the stopper 230. Here, the stainless steel case 210 and the stopper 230 are configured to be disassembled and assembled by a screw coupling method.

The stainless steel case 210 is made of stainless steel, and a specific manufacturing method thereof will be described in detail with reference to FIG.

4 is a flowchart illustrating a manufacturing process of the recycled stainless steel case for a water purifier shown in FIG. As shown in FIG. 4, in manufacturing the stainless steel case 210 according to this embodiment, a pipe making step (S210) for manufacturing a stainless steel pipe using a stainless steel material is performed. That is, a stainless steel plate having a thickness of about 0.3 to 0.6 mm (0.3 to 0.6t) is inserted into a pipe making machine, and the pipe is formed into a pipe shape by passing through a plurality of rollers. (Step S210).

Thereafter, a stainless steel pipe manufactured through the pipe making step (S210) is inserted into a metal mold having a shape of a case to be manufactured, and a high pressure bulging process is performed to apply a high water pressure to the inserted stainless steel pipe A case forming step S220 of forming a case by expanding the case is performed. At this time, at least one side is formed to have a thread forming portion.

In general, stainless steel has good elongation and tensile strength, but low hardness. However, when the above-described high-pressure bulging process is performed, the stainless steel pipe is hardened in the process of being molded in the same shape as the shape of the mold by the high-pressure force, so that the hardness of the material becomes twice as much as the hardness of the raw material. That is, the raw material Hv of the stainless steel pipe is about 116 to 128. After the high-pressure bulging process, the Hv of the material becomes about 210 to 230. Therefore, even if a stainless steel pipe having a thickness of 0.3 to 0.6 mm (0.3 to 0.6 t) is used, the stainless steel case of this embodiment of the desired specification can be manufactured. In addition, when a high-pressure bulging process is used, the stainless steel case having the same shape as that of the metal mold, that is, the stainless steel case of the desired shape can be manufactured, so that not only the working process can be reduced, but also a thinner material can be manufactured.

When a stainless steel case of a desired shape is manufactured through the case forming step S220 as described above, a sealing surface forming step of forming a sealing surface by performing an inlet portion curling process in which the inlet portion of the case is rounded outwardly (S230). Such an inlet portion curling process is performed to round the inlet portion of the case in the outward direction to widen the surface area at the upper end of the inlet portion of the case. As the surface area of the upper end of the inlet of the case becomes wider through the sealing surface forming step S230, the contact between the sealing packing 240 inserted between the case 210 and the cap 230 and the upper end of the inlet of the case The area is widened and a more efficient sealing effect can be obtained. The case forming step S220 of this embodiment is adopted in consideration of the difficulty of sealing at the case inlet of a thin thickness because the thickness of the case inlet portion must be made thin by using the thin stainless steel pipe.

On the other hand, in performing the sealing surface forming step S230, it is preferable to perform the inlet portion curling process so that a sealing surface having a garden shape is formed at the upper end of the inlet portion. To this end, in this embodiment, a curling process of the pressurized inlet portion is performed in a state where a mold capable of curling in the form of a garden is used, and the jig is used to accurately position the inlet portion in the mold.

Thereafter, a screw thread is to be formed on the lower side of the inlet portion to be disassembled and assembled with the stopper (230). However, in the case of performing a screw rolling process for forming a screw thread in this state because the thread forming region has a horizontal plane shape, the thread is not formed symmetrically with respect to the center line, There is a problem in that it is molded or formed in such a form that the thread protrudes not only outward but also inward.

Thus, in this embodiment, a thread forming portion expansion step (S240) is performed to expand the thread forming portion outwardly before the thread rolling process is performed. In this thread forming part expanding step S240, the urethane rubber is inserted into the thread forming part and the metal jig is pressed on one side in a state where the metal jig is positioned on both sides, To expand. At this time, since the thread forming portion has a stepped shape on both sides thereof, the thread forming portion is constrained and less expanded, and the central portion is expanded most.

A thread forming step S250 is then performed to form a thread in the expanded thread forming portion through a screw rolling process. Here, in the screw rolling process, since it is impossible to directly form a screw thread on the outer surface of the screw thread forming portion as the thickness of the screw thread forming portion is small, the thread rolling operation is performed by pushing the screw inward from the outer side . That is, in a state in which a first metal mold having a roller shape corresponding to a desired thread shape is positioned inside the thread forming section and a second metal mold having a roller shape having a thread corresponding to the first metal mold is positioned outside the thread forming section, 1, the second mold is operated to form a thread projecting outwardly. Therefore, a thread groove corresponding to the thread is formed on the inner side surface of the thread projecting to the outside. In addition, the initial horizontal plane where no thread is formed is deformed and has the original horizontal plane shape. The reason why the portion other than the thread is retained in the original horizontal plane shape is the experimental result according to the expansion of the thread forming portion S240 before the thread forming step S250.

Thereafter, a bottom forming step (S260) for forming a bottom portion is performed through a hard plate welding process for sealing the side opposite to the inlet portion of the case. Here, the end plate is made of stainless steel material having a convex dish shape toward the upper side, and is bonded to the inner side surface of the case by an alkaline welding method to form the bottom portion of the case. At this time, the hard plate is Alcor welded to the inner surface of the case so that the convex portion faces the upper direction of the case. In this embodiment, if the bottom of the case is formed using a dish-type rigid plate, the deformation of the case is prevented, and in the case of excessive pressure, the deformation of the case can be easily confirmed when the case is reused, To understand the problem easily (see FIG. 5). FIG. 5 is a front view comparing the steady state and the abnormal state of the recycling stainless steel case for a water purifier shown in FIG. 2;

Then, an end product finished step (S270) for completing the finished stainless steel case finished product is performed through a post-treatment process or the like.

In manufacturing the stainless steel case 210 according to this embodiment, it is most preferable to manufacture the stainless steel case 210 according to the above-described manufacturing procedure. That is, after the sealing surface formation step S230 is performed through the inlet portion curling process so that the dimensional change does not occur in the threads, the thread forming portion expansion step S240 and the thread forming step S250 for thread formation are performed will be. However, it is also possible to perform the sealing surface forming step S230 through the inlet portion curling process after the thread forming portion expanding step S240 and the thread forming forming process S250 for thread forming are performed. However, in the case of performing the bottom forming step S260 before the sealing surface forming step S230, since the one side is closed, the inlet part is accurately positioned in the mold for curling process at the inlet curling step When the bottom forming step S260 is performed before the thread forming portion expanding step S240, the metal jig necessary for thread formation is inserted into the case of the stepped shape because one side is closed. It is impossible. Therefore, the sealing surface forming step S230 of this embodiment should be performed after the inlet portion curling process and the screw rolling process are completed.

This embodiment stainless steel case 210 is even with the raw material (STS 304) of the sheet as produced by the process, the thickness of 0.3t ~ 0.6t with the desired specifications (pressure: 20Kg / cm ^2, Breaking pressure: 38 kg / cm < ² >), it is possible to remarkably reduce the manufacturing cost. That is, by using the above-described manufacturing method, the inner pressure and the breaking pressure of the stainless steel case are greatly improved. In addition, since the thread to be disassembled and assembled with the stopper 230 is formed by a rolling method using a roller-shaped metal mold, the height and width of the thread can be increased, and the fastening force with the stopper is greatly improved.

The filter filler 220 is installed inside the case 210 to filter foreign substances or harmful substances contained in the raw water, and is similar to a general filter filler.

The cap 230 is screwed into a thread formed on one side of the case 210 to seal the inside of the case 210 so as to position the filter filling material 220 inside the case 210, Gt; 220 < / RTI > The cap 230 is configured to have an inlet through which raw water flows into the case 210 and an outlet through which the filtered purified water is discharged. The plug 230 may be manufactured by injection molding using a plastic material or may be made of a metal material.

The filter 200 for a water purifier of this embodiment is used for a predetermined period of time to disassemble the plug 230 from the stainless steel case 210 to remove the filter filler 220 from the case, And then a new filter filler may be inserted into the stainless steel case 210 and then screwed into the plug 230. In this case,

≪ Embodiment 2 >

The filter for purifier according to this embodiment has the same configuration as that of the filter for purifier of the first embodiment except that the raw water flowing into one inlet port is filtered and then discharged through the outlet port on the opposite side to the inlet port And is manufactured. Therefore, in this embodiment, description of the same or similar components and manufacturing processes as those of the first embodiment will be omitted.

FIG. 6 is an exploded cross-sectional view showing a configuration of a filter for a water purifier having a recycled stainless steel case for a water purifier according to a second embodiment of the present invention, and FIG. 7 is an end view of the water purifier filter shown in FIG.

6 and 7, the water purifier filter 300 according to the present embodiment includes a stainless steel case 310 having an internal space of a predetermined size, and a stainless steel case 310 installed inside the stainless steel case 310, A filter filler 320 for filtering foreign substances or harmful substances and a filter filler 320 disposed inside the stainless steel case 310 so as to be screwed to both sides of the stainless steel case 310 so as to seal the stainless steel case 310, A pair of plugs 330 having an inlet or an outlet communicating with the case 310 and a pair of sealing packings 340 inserted between the stainless steel case 310 and the pair of plugs 330, . Here, the stainless steel case 310 and the pair of plugs 330 are constructed so as to be disassembled and assembled by a screw coupling method.

The stainless steel case 310 is made of stainless steel, and a specific manufacturing method thereof will be described in detail with reference to FIG.

8 is a flowchart illustrating a manufacturing process of the recycled stainless steel case for a water purifier shown in FIG. As shown in FIG. 8, in manufacturing the stainless steel case 310 according to this embodiment, the same pipe making step (S310) as the pipe making step (S210) of the first embodiment is performed.

Then, a case forming step S320 similar to the case forming step S220 of the first embodiment is performed. At this time, the case forming step S320 is performed so as to have a thread forming portion on both sides of the case. Thereafter, an inlet portion curling process is performed to round both sides of the case, that is, the inlet portion and the outlet portion, in an outward direction to perform a sealing surface forming step S330 for forming a sealing surface. The sealing surface forming step S330 may be performed in the same manner as the sealing surface forming step S230 of the first embodiment.

Then, a thread forming part expanding step (S340) similar to the thread forming part expanding step (S240) of the first embodiment is performed. At this time, the thread forming portion expanding step (S340) is performed in the thread forming portion formed on both sides of the case. Thereafter, a thread forming step S350 similar to the thread forming step S250 of the first embodiment is performed. At this time, the thread forming step S350 is performed in each of the expanded thread forming portions on both sides of the case. Then, an end product finished step (S360) is performed to complete the finished stainless steel case finished product through a post-treatment process or the like.

While the present invention has been described in connection with the accompanying drawings, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. Examples or modifications will also fall within the scope of the claims of this invention.

200: Filter for water purifier 210: Stainless steel case
220: filter filler material 230: plug
240: Sealing packing

Claims (9)

A case forming step of forming a case having a thread forming portion on one side through a bulging process for forming a pressure on the stainless steel pipe inserted in the mold,
A sealing surface forming step of forming a sealing surface through an inlet portion curing process in which the inlet portion of one side is rounded outward to widen the surface area of the top portion of the inlet portion;
A thread forming portion expanding step of expanding the thread forming portion outwardly,
A thread forming step of forming a thread projecting outward in the thread forming portion by using roller type dies for rotating and supporting the expanded thread forming portion from the inside and pressing and rotating from the outside to the inside direction,
And forming a bottom portion by sealing the side facing the inlet portion of the case. A case forming step of forming a case having a thread forming portion on one side through a bulging process for forming a pressure on the stainless steel pipe inserted in the mold,
A thread forming portion expanding step of expanding the thread forming portion outwardly,
A thread forming step of forming a thread projecting outwardly in the thread forming portion by using roller type dies for rotating and supporting the expanded thread forming portion from the inside to the outside and pressing and rotating from the outside to the inside,
A sealing surface forming step of forming a sealing surface through an inlet portion curing process in which the inlet portion of one side is rounded outward to widen the surface area of the top portion of the inlet portion;
And forming a bottom portion by sealing the side facing the inlet portion of the case. The method according to claim 1 or 2,
Wherein the bottom forming step comprises welding a dish-shaped stainless steel plate, which is convex upward, to form a bottom part of the stainless steel case. A recycled stainless steel case for a water purifier, which is manufactured by the manufacturing method according to claim 1 or claim 2. A filter filler disposed inside the case to filter foreign substances and harmful substances contained in the raw water; and a filter filler which is screwed to one side of the case so as to seal the case, A filter for a water purifier, comprising: a plug having an inlet port and an outlet port for placing the filter filler material in communication with the case; and a sealing packing inserted between the case and the plug,
Wherein the case is a recycled stainless steel case for a water purifier manufactured by the manufacturing method according to claim 1 or claim 2. A case forming step of forming a case having a thread forming portion on both sides through a bulging process in which a stainless steel pipe inserted in a mold is molded under pressure,
A sealing surface forming step of forming respective sealing surfaces through an inlet portion and an outlet portion curing process for widening the surface area of the inlet portion and the outlet portion by rounding the inlet portion and the outlet portion on both sides in the outward direction,
A thread forming portion expanding step of expanding the thread forming portion in the outward direction,
And a thread forming step of forming each thread protruding outward in the thread forming portion by using roller type dies that rotate and support the expanded thread forming portion from the inside to the outside and rotate inward from the outside, A method of manufacturing a recyclable stainless steel case for a water purifier. A case forming step of forming a case having a thread forming portion on both sides through a bulging process in which a stainless steel pipe inserted in a mold is molded under pressure,
A thread forming portion expanding step of expanding the thread forming portion in the outward direction,
A thread forming step of rotating the expanded thread forming part from inside to form a thread and projecting outward in the thread forming part using roller type dies which are pressed and rotated from the outside to the inside direction;
And a sealing surface forming step of forming respective sealing surfaces through an inlet portion and an outlet portion curing process for widening the surface areas of the inlet portion and the outlet portion by rounding the inlet portion and the outlet portion on both sides in the outward direction Wherein the stainless steel case is made of stainless steel. A recycled stainless steel case for a water purifier, which is manufactured by the manufacturing method according to claim 6 or 7. A filter filler disposed inside the case to filter foreign substances and harmful substances contained in the raw water; and a filter filler which is screwed to both sides of the case so as to seal the case, A pair of plugs having an inlet or an outlet for placing the filter filler in communication with the case and a pair of sealing packings respectively inserted between the case and the pair of plugs, ,
Wherein the case is a recycled stainless steel case for a water purifier manufactured by the manufacturing method according to claim 6 or claim 7.

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