JPH03170232A - Processing method for thin wall pipe - Google Patents

Abstract

PURPOSE:To improve the concentric accuracy of a pipe, by finishing a thin wall pipe in a thick wall shape at its face, press-fitting the core metal on which a hard resin is subjected to coating, fixing one end thereof by a chuck, finishing an intermediate part by wire cut electric discharging at its both ends after its electric discharging and executing the external face working of a thin wall pipe without deformation. CONSTITUTION:After processing a thin wall pipe 1 in the specific outer diameter dimension from a round bar like work, the internal face is subjected to a primary working with a lathe turning and finished smoothly with a free abrasive grain processing or electrochemical machining, etc., further. The external face is then subjected to coating by a hard resin 2, the core metal 3 worked by setting to the inner diameter of the pipe 1 is press-fitted into the pipe 1 and fixed by a screw 5. The opposite side of the fixed end is fixed to the chuck of a lathe, the screw 5 is removed after machining the center part excepting the thick wall parts of both ends of the pipe 1 in the specific dimension by a lathe turning and the core metal 3 is drawn out of the pipe 1. The pipe 1 is completed by executing the finishing of the thick wall parts of both ends of the pipe 1 with a wire cut electric discharging thereafter.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for treating the outer surface of a thin-walled pipe.

[Conventional technology]

Thin-walled pipes are usually produced by a drawing process, and the inner diameter may be finished, but the outer diameter is usually used as is. However, as a special example, an expansion cylinder with a diameter of several ribs and a length of 10, such as the expansion cylinder of a cooler for an infrared sensor that uses a low-temperature, hard-to-liquefy gas such as helium as a refrigerant,
Processing the outer surface of a thin-walled pipe of about 0.1 cm to make the wall thickness 0.1 m
There is something that must be finished below m. This expansion cylinder is equipped with a cooling section for an infrared sensor at its tip, and is cooled by expansion of refrigerant gas. A thin-walled cylinder 6 serving as an expansion cylinder is shown in FIG. The inner surface is finished extremely smooth using conventional techniques such as grinding such as honing or electrolytic machining in order to move the piston that expands and transports the refrigerant. The reason why the wall thickness is made as thin as 0.1 +++ m or less is to provide a high heat transfer resistance to the cylinder wall and suppress the intrusion of heat into the cooling section provided at one end. Both ends are thick to some extent in order to connect to the cooling part and support part, respectively, but they are still 0.2mm to 0.3n+.
It is only about 100 ft thick. In this way, it is necessary to finish the outer surface of the thin-walled pipe I whose outline is shown by the dotted line in the stepped thin-walled cylinder 6 by cutting or grinding. There is a very high possibility that the thin-walled pipe 1 will be deformed during processing as the cylinder 6. Therefore, it was necessary to either significantly reduce machining accuracy, or to use the depth of cut as the minimum source to minimize the resistance force during machining, and instead to reduce the amount of force over a long period of time. In addition, the inner surface of the thin-walled pipe is primarily processed by turning, and then finished by fixed or free abrasive processing or electrolytic processing.
After machining, one end of the thin-walled vibrator is fixed, the middle part of the thin-walled pipe excluding both ends of the outer surface is turned using the inner surface as a reference, and both ends of the outer surface are finished by wire cant electric discharge machining. Method (Special farm 1986-18
No. 2021) has been filed by the same applicant. However, this method has a limit to the accuracy of concentricity of thin-walled pipes.

[Problems to be Solved by the Invention] As a method of rubbing the thin-walled pipe so that it does not deform during processing, there is a method of inserting a core metal such as a mandrel inside the thin-walled pipe 1, or a method of rubbing the thin-walled pipe 1 so that it does not deform. 10
There is a method of melting and filling an alloy with a low melting point of 0°C, solidifying it, and then processing it. However, in the method of inserting a mandrel, the concentricity between the inner diameter and the outer shape of the thin-walled cylinder 6 is distorted due to the dimensional margin between the inner wall of the pipe for inserting and removing the mandrel, and the concentricity of the inner diameter and the outer shape of the thin-walled cylinder 6 is 10 μm which is required for the thin-walled cylinder 6. There is a risk that the following conditions may not be met. To avoid this, it is possible to consider a method in which the outer periphery of the mandrel is divided into several parts, movable in the radial direction, and brought into close contact with the inner surface of the thin-walled pipe 1, but this increases the processing cost of the mandrel. On the other hand, in the method of filling with a low melting point alloy, a separate heat source is provided, and the heating, cooling, and
Not only is reheating required for removal, but the accompanying temperature change may deform the thin-walled pipe 1 or the thin-walled cylinder 6. In addition, the pipe is filled with microparticle powder and temporarily sealed under pressure with end plugs, and both end plugs are supported on the central axis of the thin-walled pipe to process the outer surface of the thin-walled pipe. There is also a method to do this, but it requires work to fill the vibrator with fine powder and to remove the fine powder after processing the external surface. This invention solves the above-mentioned problems and provides a processing method that allows the outer surface of the thin-walled pipe to be warped without deforming it, the concentricity of the thin-walled pipe to a predetermined level, and the T-shape work to be performed easily. The purpose is to provide.

[Means to solve the problem]

The above purpose is to firstly process the inner surface of a thin-walled pipe by turning, and then finish it by fixed or free abrasive processing or electrolytic processing, and then coat the outer surface with a hard resin to match the inner diameter of the thin-walled pipe. Insert a cored metal whose outer diameter has been machined to fit into the thin-walled pipe, fix one end of the thin-walled pipe with a screw, fix the other end with a chuck of a lathe, and turn the middle part of the outer surface of the thin-walled pipe. This is achieved by processing and then applying a wire cut discharge force to both ends of the outer surface of the thin-walled vibrator. 5

[For use]

In this invention, when turning the middle part of a thin-walled pipe excluding both ends, a core metal whose outer surface is coated with hard resin is inserted into the thin-walled pipe, so the thin-walled pipe can be machined without the risk of deformation. can. In addition, since both ends are machined with a wire cutter, there is no resistance during machining, and the thin-walled pipe can be shaped without deforming it.

【Example】

Embodiments of the present invention will be described below based on the drawings. 1st
The figure is a cross-sectional view showing processing of a thin-walled vibrator according to Example 6 of the present invention, and FIG. 2 is a cross-sectional view of a thin-walled cylinder. In FIG. 1, after a thin-walled vibrator l is machined to a predetermined outer diameter from a nine-rod workpiece, the inner surface is primarily processed by turning and then smoothed by fixed or loose abrasive processing, or electrolytic processing. Thereafter, a core metal 3 whose outer surface is coated with hard resin 2 and whose outer diameter has been processed to match the inner diameter of the thin-walled pipe 1 is press-fitted into the thin-walled pipe 1, and the washer 4
Fix it with screws 5 through. 6 The purpose of coating the core metal 3 with the hard resin 2 is to avoid damaging the inner surface of the thin-walled pipe I when press-fitting the core metal 3 into the thin-walled pipe 1, and to increase the outer diameter of the thin-walled pipe 1. This is to prevent the thin-walled pipe 1 from deforming. The end opposite to the end fixed with the screw 5 is fixed to a chunk of a lathe (not shown), and the central part of the thin-walled pipe 1, excluding the thick-walled parts at both ends, is machined to a predetermined size by turning. After processing the central part, remove the screw 5 and pull out the core bar 3 from the thin-walled vibrator 1. After that, the thick parts at both ends of the thin-walled pipe 1 are finished by wire-cut electrical discharge machining.
complete. Wire-cut electric discharge machining is a method in which an extremely thin metal wire of approximately 0.02 to 0.35 nm+m is used as a tool electrode, and electric discharge machining is performed while moving the electrode or workpiece to the desired shape, and the resistance during machining is reduced. There is no deformation due to processing.

【Effect of the invention】

According to this invention, a thin-walled pipe is finished with a smooth inner surface in a thick-walled state, a cored metal coated with a hard resin is press-fitted into the inner surface of the pipe, one end of the cored metal is fixed with a chuck, and the middle part is subjected to electrical discharge machining. Therefore, there is no deformation during processing, and the concentricity of the thin-walled pipe can be finished with an accuracy of 10 μrn or less. After that, both ends are finished by wire-cut electric discharge machining, so there is no deformation of the thin-walled pipe due to machining. Moreover, the work can be done in a short time without the need for special tools.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing processing of a thin-walled pipe according to an embodiment of the present invention, and FIG. 2 is a sectional view of a thin-walled cylinder. 1: Thin wall pipe, 2: Resin, 3: Core metal, 4: Washer, 5:
screw. Shin 1 Figure 2 Figure

Claims (1)

[Claims] 1) The inner surface of a thin-walled pipe is primarily processed by turning, and then finished by fixed or loose abrasive processing or electrolytic processing, and then the outer surface is coated with a hard resin.
A core metal whose outer diameter has been machined to match the inner diameter of the thin-walled pipe is inserted into the thin-walled pipe, one end of the thin-walled pipe is fixed with a screw, and the other end is fixed with a chuck of a lathe to produce the thin-walled pipe. 1. A method for processing a thin-walled pipe, which comprises turning an intermediate portion of the outer surface of the thin-walled pipe, and then performing wire-cut electric discharge machining on both ends of the outer surface of the thin-walled pipe.