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  Method and apparatus for plating threaded portion of high pressure gas cylinderUSPTO Application #: 20070298186Title: Method and apparatus for plating threaded portion of high pressure gas cylinder Abstract: A method and apparatus for plating a threaded portion of a high pressure gas cylinder is provided. The method includes: providing a high pressure gas cylinder having a gas containing portion and a threaded portion being formed on a top of the gas containing portion; locating an anode pipe, in which a plating solution passage is formed, inside the threaded portion; forming a closed chamber containing the threaded portion and the anode pipe; forming a flux of the plating solution inside the closed chamber; and forming a voltage difference between the anode pipe and the threaded portion, and plating the threaded portion. (end of abstract) Agent: Hammer & Hanf, PC - Charlotte, NC, US Inventor: Kyung Jun Yang USPTO Applicaton #: 20070298186 - Class: 427438 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20070298186. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS-REFERENCE TO RELATED APPLICATION [0001]This application claims the benefit under 35 U.S.C. .sctn. 119(a) of Korean Patent Application Nos. 2006-0056795, filed on Jun. 21, 2006, and 2007-0037559 filed on Apr. 17, 2007 in the Korean Intellectual Property Office, the entire disclosure of both of which are incorporated herein by reference. BACKGROUND OF THE INVENTION [0002]1. Field of the Invention [0003]The present invention relates to a method and apparatus for plating a threaded portion of a high pressure gas cylinder, and more particularly, to a method and apparatus for plating a threaded portion which can maintain a unique characteristic of a corrosive gas or high-purity gas. [0004]2. Description of Related Art [0005]Various types of industrial gases are used according to purposes in business fields such as biochemistry, precision machinery industry, medical science, semiconductor industry and the like. It is very important to take appropriate treatment on the inside of cylinders to maintain a unique characteristic of a corrosive gas or a high-purity gas in the case of a predetermined process using the corrosive gas or the high-purity gas. Otherwise, the industrial gases should be contaminated by foreign substances which exist on an inside wall of a high pressure gas cylinder after being charged into the high pressure gas cylinder, and a physical or chemical characteristic of the industrial gases may be changed due to a chemical reaction occurring between the inside steel wall of a gas cylinder and the charged gas. Accordingly, appropriate treatment is required to be taken with respect to the gases to maintain the unique characteristic. [0006]To maintain the unique characteristic with respect to the industrial gases, a manufacturing method of a high pressure gas cylinder using a chemically stable material may be provided, and nickel is generally used for the chemically stable material. However, in the case of the above method, a manufacturing cost for the high pressure gas cylinder is high since a high-purity raw material is not easy to acquire. Also, in the case of the above method, a high pressure charge is comparatively difficult than a gas cylinder made of a steel, and costs for storage and transportation may be higher. [0007]Also, a method for plating a metal on an inner surface of a gas cylinder made of steel may be provided, the metal being chemically stable with respect to the industrial gases. However, as described later, it is difficult to form a flawless plating layer on a threaded portion, the threaded portion being provided with a valve, of a high pressure gas cylinder with the above-described methods. Accordingly, an expected characteristic of a charged gas may be deteriorated since the raw material of the threaded portion may chemically react to a charged gas. For a conventional method for plating, the following two methods may be taken into consideration. [0008]A first method is to form a plating layer thickly on an inside wall of the high pressure gas cylinder. In this case, the plating may be performed using a material which is chemically stable with respect to the industrial gas, and nickel is generally used for the material. A top of the high pressure gas cylinder is processed in a threaded form to couple with a valve. During the processing, the top of the high pressure gas cylinder is threaded and punctured via a mechanical process. Subsequently, a method capable of maintaining a plating layer by forming a sufficiently thick plating layer, after the machining process, may be provided. However, the thickness of the plating layer satisfying the above condition is beyond the scope that can be embodied in general electroplating. [0009]A second method is to perform a first plating with respect to an inside wall of a high pressure gas cylinder, and to perform a second plating with respect to a threaded portion after a mechanical process of the threaded portion. However, this method has problems, and the problems are disclosed in U.S. Patent Publication No. 6089399 and 7032768. Due to the following problems, a method of inserting an additional threaded portion is used in the specification of the present invention. [0010]When plating thickness is too thick, it is difficult to couple with the valve, and when plating thickness is too thin, a charged gas may be leaked via a gap between the threaded portion and the valve, and therefore, thickness for plating the threaded portion should be appropriately controlled, however, the conventional method may not control the thickness for plating the threaded portion. [0011]FIG. 6 is a cross-sectional view illustrating a shape of a plating layer being formed on a threaded portion according to a conventional method for plating. [0012]As illustrated in FIG. 6, due to a characteristics of electroplating, a plating layer 620 is thickly formed on ridges 612 of a threaded portion, in which a high current flows, and the plating layer 620 is thinly formed on pits 614 of the threaded portion, in which a low current flows, or an air pocket may be formed on the pits 614 of the threaded portion. Air pockets may cause a defect on the pits 614 of the threaded portion, such as a pit or a pin hole. Due to the defect on a threaded portion 610, a chemical reaction between a raw material of the high pressure gas cylinder and a charged gas may occur, consequently a quality of the charged gas may be deteriorated. [0013]Also, the conventional method has a problem in that micro-sized foreign substances being generated during a manufacturing process are exposed toward a surface from the pits 614 of the threaded portion to react to the charged gas. The micro-sized foreign substances being generated during the manufacturing process of the high pressure gas cylinder are isolated on the pits 614 of the threaded portion, and are exposed toward the surface of the threaded portion 610 during a plating process, consequently the exposed micro-sized foreign substances react to the charged gas to cause the above described problems. BRIEF SUMMARY [0014]An aspect of the present invention provides a method and an apparatus for plating a threaded portion of a high pressure gas cylinder which can maintain a unique characteristic of a gas, with respect to a corrosive gas or a high-purity gas, by forming a flawless plating layer on the threaded portion. [0015]Another aspect of the present invention also provides a method and an apparatus for plating a threaded portion of a high pressure gas cylinder that enables to maintain a unique characteristic of a charged gas since foreign substances being generated during a manufacturing process of the high pressure gas cylinder are not isolated on pits of the threaded portion. [0016]Another aspect of the present invention also provides a method and an apparatus for plating a threaded portion of a high pressure gas cylinder that enables to appropriately control thickness distribution of a plating layer being formed on ridges and pits of the threaded portion. [0017]According to an aspect of the present invention, there is provided a method for plating a threaded portion of a high pressure gas cylinder including: providing a high pressure gas cylinder having a gas containing portion and a threaded portion being formed on a top of the gas containing portion; locating an anode pipe, in which a plating solution passage is formed, inside the threaded portion; forming a closed chamber containing the threaded portion and the anode pipe; forming a flux of the plating solution inside the closed chamber; and forming a voltage difference between the anode pipe and the threaded portion, and plating the threaded portion. [0018]The present invention may circulate a plating solution to forcefully flow in the chamber, and the threaded portion of the high pressure gas cylinder may be plated by the circulating plating solution. Accordingly, a defect on a plating layer may be prevented by preventing occurrence of an air pocket, and may prevent foreign substances from existing on the pits of the threading portion. [0019]In the present invention, circulation of the plating solution may be performed using an anode pipe and the closed chamber, the anode pipe being formed the plating solution passage. As an example, the plating solution is provided via an inside passage of the hollow anode pipe, and the provided plating solution may be flowed into the closed chamber through the plating solution passage, the plating solution passage being formed on a side of the anode pipe. The flowed plating solution is discharged to the outside through an inlet/outlet for the plating solution so that flux of the plating solution is formed around the anode pipe. As another example, the plating solution is flowed into the closed chamber via the inlet/outlet for the plating solution, and the flowed plating solution is discharged to an outside through an opened hole of the anode pipe. Also, the anode pipe may be located inside the threaded portion and the plating solution passage may be formed in correspondence to a bottom of the threaded portion so that the plating solution smoothly flows around the threaded portion. During the circulation of the plating solution, the plating layer may be formed on the threaded portion of the high pressure gas cylinder. In this instance, a material, which is chemically stable with respect to the industrial gas, may be used to perform plating, and nickel is generally used for the plating. [0020]In the present invention, in the forming of the closed chamber, a bottom sealing portion isolates a bottom of the threaded portion from the gas containing portion, and a top sealing portion, which is formed in correspondence to the bottom sealing portion, isolates a top of the threaded portion from an outside to form the closed chamber. [0021]Also, a diameter of the anode pipe is controlled so as to control thickness of the plating layer, the plating layer being formed on ridges and pits of the threaded portion. The plating layer may be thickly formed on the ridges of the threaded portion since a high current flows through the ridges of the threaded portion, and the plating layer may be thinly formed on the pits of the threaded portion since a low current flows through the pits of the threaded portion, accordingly a portion of the plating layer may be incompletely formed. However, in the present invention, the above problem may be solved by suitably controlling the diameter of the anode pipe for plating types, the anode pipe performing as an anode. Continue reading... Full patent description for Method and apparatus for plating threaded portion of high pressure gas cylinder Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Method and apparatus for plating threaded portion of high pressure gas cylinder patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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