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Pipe fixing structure and pipe fixing methodRelated Patent Categories: Metal Working, Method Of Mechanical Manufacture, Assembling Or Joining, Joining By Deforming, Radially Expanding Part In Cavity, Aperture, Or Hollow Body, Radially Expanding Internal TubePipe fixing structure and pipe fixing method description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060236521, Pipe fixing structure and pipe fixing method. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] This invention relates to a pipe fixing structure and a pipe fixing method for fixing a pipe onto an object member by plastically deforming the pipe under an external force. [0003] 2. Description of the Related Art [0004] The conventional pipe fixing structure and method in which a pipe is fixed by caulking on an object member to which the pipe is to be fixed (hereinafter referred to simply as "the object member") is known. No reference of the prior art is known to the inventor. This conventional pipe fixing structure and method are described below. [0005] As shown in FIG. 14, a projection 104 is formed at a predetermined position on an outer peripheral portion 105 of a pipe 100, and an object member 103 is formed with an opening portion 106 into which the pipe 100 with the projection 104 can be inserted, a stopper portion 108 on the opening in contact with the forward end 107 of the pipe 100 and a holder 101 extended from the opening portion 106. [0006] As a method of fixing this pipe 100 on the object member 103, an O-ring 102 is placed on the opening portion 106, the forward end 107 of the pipe 100 is brought into contact with the stopper portion 108 and the O-ring 102 is held by the lower side surface of the projection 104. Under this condition, the holder 101 is pushed down by a punch member (not shown). The holder 101 bends down and pushes the upper side surface of the projection 104 thereby to fix the pipe 100 on the object member 103. [0007] A method is also available in which the pipe is fixed on an object by plastically deforming the pipe to a predetermined shape. As such a method, the conventional technique described in Japanese Unexamined Patent Publication No. 2003-336560 is known. In this method, the forward end of a pipe held in a chuck is pressed in the axial direction by a punch member having a predetermined shape of a depression. Then, the machining margin at the forward end of the pipe plastically flows so that the forward end of the pipe is deformed into a shape following the predetermined shape of the depression formed on the punch member. SUMMARY OF THE INVENTION [0008] In the conventional method of fixing by caulking, however, the holder 101 is projected outward from the object member 103 and, therefore the object member 103 is required to be cut or otherwise machined to form the holder 101, thereby posing the problem that the object member before machining is bulky. Also, the machining process to form the holder 101 projected outward requires a considerable amount and labor for the cutting work. [0009] The object of this invention, which has been achieved in view of the problem described above, is to provide a pipe fixing structure and a pipe fixing method whereby at least a predetermined fixing force can be secured with a simple structure without forming the outward projection of the object member. [0010] In order to achieve the object described above, this invention employs the following technical means. [0011] According to a first aspect of the invention, there is provided a pipe fixing structure for deforming and fixing a pipe (2) by applying a force to press the pipe (2) in axial direction against an object member (1, 8) to which the pipe (2) is to be fixed, the pipe fixing structure comprises an enlarged diameter portion (1a) formed in the object member (1, 8), which portion (1a) is larger than the outer diameter of the pipe (2) and through which the pipe (2) can be inserted in axial direction, and a first projection (6) into the shape of which a thin portion (2a) of the pipe (2) is deformed under the pressure, wherein the first projection (6) coincides with the enlarged diameter portion (1a). [0012] In this aspect of the invention, an enlarged diameter portion is formed in the object member, the pipe is formed with a thin portion, and the axial pressure is applied to the pipe thereby to buckle and fix the pipe. Therefore, the fixing process can be simplified with a simple fixing structure and the pipe can be fixed with at least a predetermined fixing force. [0013] According to a second aspect of the invention, there is provided a pipe fixing structure comprising a second projection (7, 15) projected radially outward from the pipe (2) and integrated with the object (1, 8) in the boundary between the fixed pipe (2) and the outer surface of the object member (1, 8). In this aspect of the invention, the expansion of the second projection further strengthens the fixing force between the pipe and object member. [0014] According to a third aspect of the invention, there is provided a pipe fixing structure wherein the second projection (15) is formed in a substantially uniform thickness along the shape of the outer surface of the object member (1). In this aspect of the invention, the second projection is formed along the shape of the outer surface of the object member in the boundary between the pipe and the outer surface of the object member. Therefore, the coupling portion is less visible and burrs or the like edge portions of the second projection can be reduced. [0015] According to a fourth aspect of the invention, there is provided a pipe fixing structure wherein the cross section of the enlarged diameter portion (1a) in axial direction of the pipe (2) is progressively reduced outward. In this aspect of the invention, the cross section of the enlarged diameter portion in axial direction of the pipe is progressively reduced outward. Therefore, the first projection of the pipe plastically flows in close contact with the progressively reduced shape. Thus, the gap between the object member and the pipe is reduced to increase the closeness and the fixing force. [0016] According to a fifth aspect of the invention, there is provided a pipe fixing structure wherein the object member is an ejector for the refrigeration cycle. [0017] According to a sixth aspect of the invention, there is provided a pipe fixing method comprising the steps of forming a thin portion (2a) on the inner peripheral portion of the pipe (2), forming the enlarged diameter portion (1a), at a position corresponding to the thin portion (2a), through which the pipe (2) can be axially inserted, in the object member (1, 8) to which the pipe (2) is fixed, and inserting the pipe (2) into the object member (1, 8) and pressing the pipe (2) in axial direction so that the thin portion (2a) is deformed by being projected outward into coincidence with the enlarged diameter portion (1a). [0018] In this aspect of the invention, after the comparatively simple process of forming a thin portion of the pipe and an enlarged diameter portion in the object member, the pipe is axially pressed and buckled. Thus, a pipe fixing method high in workability, buckling process quality and fixing force is realized. [0019] According to a seventh aspect of the invention, there is provided a pipe fixing method wherein the pipe (2) inserted into the object member (1, 8) is pressed in axial direction in such a manner that the outer peripheral portion of the pipe (2) is gripped by a chuck (3, 13), and the chuck (3, 13) is moved in axial direction. In this aspect of the invention, the pressure exerted on the pipe can be adjusted easily by moving the chuck mechanically in axial direction. Therefore, a fixing method is obtained in which the deformation amount of the thin portion and the closeness between the thin portion and the enlarged diameter portion can be easily adjusted. [0020] According to an eighth aspect of the invention, there is provided a pipe fixing method comprising the step of deforming the thin portion (2a) into coincidence with the enlarged diameter portion (1a), followed by applying pressure to the pipe (2) thereby to buckle the pipe (2) in the boundary between the fixed pipe (2) and the outer surface of the object member (1, 8). [0021] In this aspect of the invention, the second projection expanding outward is formed by buckling the pipe in the boundary between the fixed pipe and the outer surface of the object member, thereby further strengthening the fixing force between the pipe and the object member. [0022] According to a ninth aspect of the invention, there is provided a pipe fixing method wherein the chuck (3, 13) moved in axial direction while gripping the outer peripheral portion of the pipe (2) has, on the side thereof for gripping the pipe (2), an end surface (14) in opposed relation to the outer surface of the object member (1, 8), which end surface (14) is formed along the shape of the outer surface of the object member (1, 8). Continue reading about Pipe fixing structure and pipe fixing method... Full patent description for Pipe fixing structure and pipe fixing method Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Pipe fixing structure and pipe fixing method 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. 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