JPS6096333A - Holding method of cylinder - Google Patents

Abstract

PURPOSE:To make construction simple and initial cost low by mounting a restraining cylinder to the outside of a cylinder or split cylinders to be internally exerted with pressure and pressurizing the space therebetween by a pressure medium thereby offsetting and relieving the internal stress exerted on the cylinder or split cylinders. CONSTITUTION:A restraining cylinder 16 is mounted to the outside of a cylinder or split cylinders 2 to be exerted internally with a pressure P1 and the space made by sealing hermetically the fitted part with an O-ring 17 is pressurized P2 by a pressure medium such as oil or the like. The internal pressure P1 acting on the cylinder 2 is offset and relieved by the external pressure P2 by which the pressure resistance of the cylindrical body 2 is made stronger or the wall thickness thereof is made thinner. The construction is thus simplified and the initial cost is reduced.

Description

Detailed Description of the Invention [Field of Application of the Invention] “The present invention relates to a method of holding a cylinder using pressure, and particularly to restraining a divided mold to which high pressure is applied inside and relaxing stress of a container. The present invention relates to a holding method suitable for.

[Background of the invention]

'Conventionally, various pipe fittings and bicycle parts have been molded using the hydraulic bulge process. This is a plastic working method in which a material tube is held in a split mold, and a portion of the material tube is expanded by applying hydraulic pressure and an axial compressive load to the material tube.

Fig. 1 shows an example of a hydraulic bulge processing device, in which 1 is a material tube, 2a and 2b are split molds, 3 is a mold clamping piston, 4a and 4b are pressure pistons, and 5 is a Hydraulic pump, 6 is high pressure liquid introduction hole, 7 is pressure intensifier, sa, sb are pressure cylinders, 9 is hydraulic pump, 10 is mold clamping cylinder, 1
1 is a hydraulic pump.

To briefly explain how to perform bulge processing using such a device, first, the material tube 1 is inserted into the upper and lower split molds 2a and 2b, and the mold clamping piston 3 of the mold clamping cylinder 10 is pressed. to restrain the split mold. Next, the pressure fluid generated by the hydraulic pump 5 is supplied to the pressurizing cylinders 8a, 8b, the pressurizing pistons 4a, 4b are advanced, and the tips of the pistons are pressed against the material tube to seal it. In this state, the high pressure liquid generated by the hydraulic pump 9 and the pressure intensifier 7 is supplied into the material pipe from the high pressure introduction hole 6, and the pressure liquid generated by the hydraulic pump 5 is supplied to the pressurizing cylinder 8a.

8b, and compresses the material tube in the axial direction to expand it into a predetermined shape.

In the hydraulic bulge processing apparatus shown in Fig. 1, the split mold is restrained by a mold clamping cylinder 10 to prevent the split mold from separating when high pressure is applied inside the material pipe. The load can be roughly estimated using equation (1).

Here, W: Restraining load of the split mold (Kyf) D = Inner diameter of the material tube (ttrm) t: Length of the material tube + m) p: Hydraulic pressure added inside the material tube (Kgf/cm 2) For example, the inner diameter 100wn5 length 400mm pipe with hydraulic pressure 10
When performing bulge processing at 00 Kg f/cm", the restraining load of the split mold is 400 tmf, and a mold clamping cylinder that can generate this load is required. Therefore, such a large capacity mold clamping cylinder is required. Conventional hydraulic bulge processing equipment has the disadvantage that equipment costs are very high.

On the other hand, cold isostatic pressing is a method for compression molding metal powder or ceramic powder. As shown in FIG. 2, the powder 13 is sealed in an elastic body 612 such as rubber, the elastic container is inserted into the high pressure container 14, and the high pressure liquid p is supplied into the high pressure container. This is a method of compression molding the PJr foot into the shape of the PJr foot.

In cold isostatic pressing equipment, if a unidirectional cylinder is used for the high-pressure container into which the high-pressure liquid is applied, it will be large. A wire-wound structure is used.

These methods apply compressive residual stress to the high-pressure vessel in advance to reduce stress in the high-pressure vessel that occurs when high-pressure liquid is added. However, the compressive residual stress imparted by the shrink-fit structure and the wire-wound structure has the drawback that it is not uniform throughout the design and that it requires a large number of man-hours to manufacture.

[Purpose of the invention]

An object of the present invention is to provide a method for holding split molds and cylindrical containers to which high pressure is applied internally, which can be realized with a simple structure and low equipment costs.

[G concubine of invention]

The main point of the present invention is to provide a method for holding a divided mold and a container to which high pressure is applied inside, including a cylinder enclosing a medium at a pressure lower than the pressure on the outer periphery of the divided mold and the cylindrical container. The low pressure restrains the splitting mold and relieves stress on the cylindrical container.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to FIGS. 3 to 6. FIG. 3 shows a hydraulic bulge processing apparatus according to an embodiment of the present invention. Figure 3 shows only the restraining part of the split mold in Figure 1.
In the figure, 16 is a split mold restraining cylinder, 17 is an 0 ring,
Pt represents the molding pressure applied inside the material tube, and p2 represents the hydraulic pressure for restraining the split mold. Moreover, FIG. 4 shows the Ahm plane of FIG. 3, and in this figure, 18 indicates a self-tightening type delta packing. In this example, 1 cumulative material view 1
The split molds 2a, 2 generated due to the molding pressure pl applied inside
The split mold is restrained by combining the separation load b and a restraining load generated by supplying hydraulic pressure p2 into the restraining circular portion 16 disposed on the outer periphery of the split mold.

The separation load W1 per unit length of the split mold can be roughly estimated using equation (2).

On the other hand, the restraint load W2 can be roughly estimated using equation (3).

Here, Do: Outer diameter (mm) of the split mold. Therefore, the hydraulic pressure p2 required to restrain the split mold is expressed by equation (4).

As can be seen from equation (4), if the ratio between the inner diameter of the material pipe and the outer diameter Do of the split mold is appropriately selected, the hydraulic pressure p2 can be made low. For example, when bulging a material pipe with an inner diameter of 100 mm using a hydraulic pressure of 1000 Ky f 7 cm, if the outer diameter of the split mold is 300 m, the hydraulic pressure p2 will be 330 Kg.
It can be restrained with a stable of about f/lyn'', and the thickness of the restraining cylinder only needs to be about 25 cylinders.

The sealing of the hydraulic pressure p2 applied within the restraint cylinder is performed by O-rings 17 disposed at both ends of the cylinder, and the sealing in the open can type is performed by a self-containing type delta packing 18.

FIG. 5 is a modification of the embodiment shown in FIGS. 3 and 4, and shows an example in which pressure pxf is applied by rubber pressure to restrain the split mold. In the figure, reference numeral 19 indicates an elastic pressure medium such as rubber.

In the process of applying hydraulic pressure p1 and axial compression load to the material tube 1 using the pressure pistons 4a and 4b, the material tube contracts in the axial direction.Using this, the pressure medium 19 is compressed in the axial direction by the pressure piston. Then, the split mold is restrained by the side pressure of the pressure medium generated at that time. In addition, in Fig. 5 (7), the pressure medium is compressed by a pressurizing piston, but
Other pressure means may also be used.

FIG. 6 shows an embodiment in which the present invention is applied to a hydrostatic press forming apparatus. In the figure, 20 is a holding cylinder, 21 is O
Showing links.

To explain the method of compression molding powder using such a hydrostatic molding device, first, a fluid at a pressure p2 is supplied into the holding cylinder 20 using a quasi-pressure pump (not shown).

At this time, compressive stresses σt, σ1° are generated in the high-pressure vessel 14 as shown by the equation (51+t6).

Cylindrical Stress Radial Stress Thereafter, a molding pressure p1 is applied in the high-pressure container 14 to compress and mold the powder 13 enclosed in the elastic container 12. At this time, the high-pressure vessel has (force, stress σ11 as shown in equation (8)
．． σ1t occurs.

(8) Cylindrical stress Radial stress Therefore, the cylindrical stress σt1 radial stress σ of the high-pressure vessel is (9L (equation 11), (5), <6
) can be reduced by the amount of compressive stress shown in the equation.

In formula (9), 001, by appropriately selecting the ratio of pt and 5I)s, the tensile stress of the high-pressure container can be alleviated, and the wall thickness of the holding cylinder can be made thinner.

As described above, according to the embodiment of the present invention, by disposing a cylinder for enclosing a low-pressure pressure medium around the outer periphery of the divided mold in the hydraulic bulge processing device (9), the division is performed. The mold can be restrained, and conventional EC
+! The large-capacity mold clamping cylinder used in the previous model can be omitted. 1. In cold isostatic pressing equipment,
Since compressive stress can be applied to the pressurized container and tensile stress generated during molding can be alleviated, the structure can be simplified compared to conventional devices, and the number of manufacturing steps can be reduced. Furthermore, since the entire stress distribution of the high-pressure vessel can be accurately grasped, the construction of the ridge becomes easy.

[The infancy of invention]

According to the present invention, it is possible to maintain a divided mold and a cylindrical container in which high pressure is applied with a simple structure and at low equipment cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional hydraulic bulging device, FIG. 2 is a sectional view of a conventional cold isostatic pressing device, and FIG. 3 is a sectional view of a hydraulic bulging device according to an embodiment of the present invention. Figure, 4th
The figure is a sectional view taken along the line A-A of the apparatus shown in FIG. 3, FIG. 5 is a sectional view of a modification of the embodiment shown in FIG. 3, and FIG. FIG. 2 is a sectional view of an isostatic pressing apparatus. 2a, 2b...Split mold, 16...Restriction cylinder, 19.
...Elastic pressure medium, 20...Retaining circular surface. Agent Patent Attorney Akio Takamichi (11) Nagisa 111a 0 vJ Z Mouth Figure 3 Figure 4 Figure 5 Figure B

Claims (1)

[Claims] 1. In a method of holding a cylinder to which pressure is applied inside, a restraining cylinder is attached to the outside of the cylinder, and pressure is applied to the gap between the restraining cylinder and the cylinder using a pressure medium. A method for holding a cylinder, characterized in that compressive stress is applied to the cylinder. 2. Holding the cylinder according to claim 1, wherein the cylinder is divided into two or more parts, and the divided cylinder is restrained in the radial direction by the pressure generated by the pressure medium. Method.