JPS62213927A - Machining method for thin wall cylindrical body made of fiber reinforced plastic - Google Patents

Abstract

PURPOSE:To shorten working time and improve machining reliability by machining the external surface of a cylindrical body with a core body formed in double structure consisting of an elastically deformable external pipe and an internal pipe fitted to the external pipe concentrically and with pressure fluid introduced between both pipes to make the core body contact tightly with internal surface of a thin cylindrical body made of fiber reinforced plastics. CONSTITUTION:In order to form a core body 10, an external pipe 14 whose outer diameter is smaller than the inner diameter of a cylindrical body 1 made of fiber reinforced plastics (FRP) is fitted to the periphery of an internal pipe 11 elastically deformable and concentrically with the internal pipe 11, and a pressure adding chamber 15 is provided between both pipes 11 and 14, and a pressure keeping means 18 is inserted into a pressure fluid introducing passage 17. And the core body 10 is inserted into the FRP cylindrical body, and pressure fluid is introduced into the pressure adding chamber to expand the external pipe 14 radially for making it contact tightly with the internal surface of the cylindrical body 1 and the pressure in the chamber is kept constant by the pressure keeping means 18. The external surface of the cylindrical body 1 can, therefore, be machined using the core body 10 as reference and the core body 10 can be readily removed by relieving the pressure in the pressure adding chamber 15. Therefore, working time can be shorten, and machining reliability can be improved.

Description

Detailed Description of the Invention [Industrial Application Field] This invention relates to a method for processing a continuous fiber-reinforced plastic cylinder (hereinafter referred to as an FRP cylinder). This invention relates to a method for improving workability during machining for the purpose of reducing.

[Conventional technology and its problems]

FRP cylindrical bodies are often manufactured by wrapping resin-impregnated continuous fibers around a mold with a circular cross section, curing the resin by heating, and then removing the mold from the mold. Since uneven thickness tends to occur, it is necessary to remove it. In particular, processing is essential for FRP cylinders for wall materials of pressure-resistant containers that require high precision, FRP high-speed rotation cylinders, and the like.

On the other hand, FR is said to be lightweight, high strength, and high elasticity.
In order to take advantage of the properties of P, it is required to minimize the amount of fiber breakage after molding. Especially in the case of thin-walled cylinders,
That demand is strong. Therefore, the FRP obtained by the above method
Generally, the inner surface of the cylindrical body remains as it was when it was removed from the mold.
In many cases, only the outer surface is machined to remove uneven thickness.

As shown in FIG. 4, the conventional method for machining the outer surface is to insert the core body 2 into the inside of the FRP cylindrical body 1 so as to generate a frictional force against the cylindrical body.
It is common to attach this to a processing machine such as a lathe or grinder to cut or grind the outer surface.

However, according to this method, a gap is likely to be formed between the FRP cylindrical body and the core body, making it difficult to increase the uneven thickness removal rate. On the other hand, if the core is forcefully pushed in to reduce the gap, the inner surface of the cylinder will be damaged.

In addition, as a countermeasure for these problems, the core body is cooled when inserted,
Although it is possible to adopt a cooling fitting method in which the temperature is returned to room temperature after insertion, this method takes time to attach and detach the core and is economically disadvantageous due to the use of cold energy. Moreover, since the FRP cylindrical body is cooled together when the core is extracted, if the cylindrical body has a relatively large coefficient of thermal expansion, it may be difficult to extract the core after processing.

The purpose of the present invention is to provide a method for processing a thin-walled FRP cylinder that is effective in solving these problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention uses a core body having a double structure consisting of an elastically deformable outer pipe and an outer pipe arranged concentrically inside the core body, In addition, a pressure chamber is provided between both pipes, and by introducing pressurized fluid into this chamber, the diameter of the outer pipe, whose outer diameter is smaller than the inner diameter of the FRP cylinder, is expanded, thereby increasing the diameter of the FRP cylinder. The inner surface of the FRP cylindrical body was machined in close contact with the inner surface, and under this condition, the inner surface of the FRP cylinder was machined using the core as a reference.

That is, the present invention makes the diameter of the core body variable to facilitate insertion into and removal from the FRP cylindrical body, and improves the adhesion of the core body to the FRP cylindrical body during machining.

〔Example〕

FIG. 1 shows an example of the core used in this invention. 10 in the figure indicates the entire core body. Reference numeral 11 denotes an inner pipe with a circular cross section, and a rotary shaft 1 is provided at both ends of the inner pipe.
An end plate 13 with 2 is fastened thereto.

On the outer periphery of the inner vibrator 11, there is provided an outer vibrator 14 which is elastically deformable and whose outer diameter is smaller than the inner diameter of the FRP cylindrical body.
are installed concentrically. Also, two pipes 11
．． 14, there is a pressure adding chamber 15 which is hermetically sealed at both ends.
is provided. Reference numeral 16 denotes a pressurized fluid introduction port, and a pressure holding means (this may be stop pulp or the like) 18 is inserted into a fluid introduction path 17 connected thereto.

It is desirable that the radial dimension S of the pressure adding chamber 15 be as small as possible, less than 10 fl, more preferably about 0.5 to 1.0 fl. This is because the change in the outer diameter of the outer vibrator 14 due to thermal expansion becomes large, causing the problem that an unreasonable diameter expanding force is applied to the FRP cylindrical body after the outer pipe is brought into close contact with the FRP cylinder.

In addition, when manufacturing the core, in order to increase the roundness of the outer pipe 14 during diameter expansion, a pressure similar to the pressure applied during machining of the FRP cylindrical body is applied in the additional chamber 15.
It is preferable to process the outer surface of the outer pipe 14 in advance. For the same reason, it is also good to keep the variation in the wall pressure of the outer pipe within ±20%. If this variation is large, the decrease in cylindricity of the core due to fluctuations in fluid pressure becomes large.

As shown in FIG. 2, the method of the present invention using the above-mentioned core includes a step of inserting the core 10 into the FRP cylindrical body 1, introducing pressurized fluid into the pressure applying chamber 15, and introducing the pressurized fluid into the outer pipe. 14,
As shown in FIG. 3, there is a step of expanding the diameter until it comes into close contact with the inner surface of the cylindrical body 1, a subsequent step of retaining the pressure in the pressurized chamber by the holding means 18, and a step of attaching the core body to a processing machine and The process is completed by sequentially completing the steps of machining the outer surface of the cylindrical body 1 based on the body and removing uneven thickness, and reducing the diameter of the outer vibrator 14 to its original size by releasing the pressure in the pressurized chamber and removing the core body. do. Note that the amount of diameter expansion of the outer pipe 14 in the diameter expansion process may be extremely small. For example, the core body can be inserted into the FRP cylindrical body without any problem if there is a gap of about 0.1 mm between the two. In this case, if the diameter of the outer pipe 14 is expanded by about 0.15w, the pipe will come into close contact with the inner surface of the cylindrical body.

〔effect〕

According to the method of the present invention described above, the effect of shortening the working time and the effect of improving the reliability of processing can be obtained.

That is, when inserting into the FRP cylinder, the outer diameter of the core is smaller than the inner diameter of the cylinder, so the core can be easily inserted without damaging the cylinder.

In addition, the outer pipe whose diameter changes with changes in fluid pressure is
Since it can be brought into close contact with the RP cylindrical body without any gaps, it is also possible to increase the uneven thickness removal rate during machining.

Furthermore, if the pressure in the pressure application chamber is released, a gap is created between the core and the cylinder regardless of the coefficient of thermal expansion of the FRP cylinder, so that the core can be easily removed.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a core body adopted in the method of the present invention, FIGS. 2 and 3 are diagrams showing a part of the working process according to the method of the present invention, and FIG. 4 is a conventional FIG. 3 is a diagram showing a processing method. 1... FRP cylindrical body, 10... Core body,
11...Inner vibe, 14...Outer vibe, 15...Pressure addition chamber, 18...Pressure holding means.

Claims (1)

[Claims] A core body in which a pressure applying chamber is formed between an elastically deformable outer pipe and an inner pipe arranged concentrically inside the outer pipe is a thin-walled fiber-reinforced plastic cylinder whose inner diameter is slightly larger than the outer diameter of the outer pipe. After inserting it into the body, pressurized fluid is introduced into the pressure application chamber to expand the diameter of the outer pipe until it comes into close contact with the inner surface of the thin-walled cylindrical body, and then the pressure inside the pressure application chamber in this state of close contact is A method for processing a thin cylindrical body made of fiber reinforced plastics, which comprises holding the thin cylindrical body by a pressure holding means and machining the outer surface of the thin cylindrical body with reference to the core body under this condition.