JPS6261719A - Composite billet for isostatic extruding of internal coating composite pipe - Google Patents

Abstract

PURPOSE:To prevent breaking of a pipe for internal coating and leaking of a pressure medium by bonding a pipe having a larger inner diameter than a mandrel inserting hole with a rear end surface of plug and by airtight working between a hollow billet of the rear end side of extruding and a pipe for coating. CONSTITUTION:A head end part of the billet is formed a solid metalic plug 3 nearly conical shaped and the coating pipe 2 is bonded to the rear end surface of said plug 3. In this case, the inner diameter of the pipe 2 is enlarged than the hole for inserting the mandrel 5 of the plug 3 and the hollow billet 1 to be a base metal is disposed around the pipe 2. the airtight work is performed between the hollow billet 1 of the rear end side of extruding and the pipe for coating 2 by welding or brazing 6', and on the rear end surface of these, bonding a stopper 4 to form the composite billet. In this way, the breaking caused by ironing the coating pipe 2 by the mandrel 5 at inserting the mandrel is prevented and the sealing at the plug part on the head end of billet is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a composite billet for hydrostatic extrusion of internally coated composite pipes.

[Prior art and problems to be solved by the invention] Conventionally, when manufacturing a metal composite pipe having a coating layer 7 on the inner surface as shown in FIG. A composite billet that is almost the same as the product is being created, but in order to prevent pressure media such as oil from flowing out from the gap between the holes in the composite billet and the mandrel at the start of extrusion, making extrusion impossible, the method shown in Figure 2 is used. As shown in the figure, the outer diameter of the tip 11 of the composite billet is made smaller than the outer diameter of the main body 12 and at the same time slightly smaller than the diameter of the mandrel 5, so that when inserting the mandrel 5, a so-called "interference fit" is achieved. I tried to make sure that they fit together in the same condition.

However, when the covering pipe 2 of the composite billet is thin or soft, when the mandrel 5 is inserted, the hard mandrel 5 may cause the m-covering pipe 2 at the reduced diameter portion at the tip of the billet to undergo local ironing. This often results in breakage or cracking. When the covering pipe 2 is broken in this way, not only does the pressure medium flow out from that part and extrusion becomes impossible, but also the covering pipe 2 has to be processed again, resulting in an extremely large economic loss.

Therefore, in order to avoid damaging the coating vibrator 2 when inserting the mandrel 5 and to achieve a sufficient seal against the pressure medium between the billet tip 11 and the mandrel 5 at the start of extrusion, we have developed a composite material. It was desired to improve the billet structure.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to overcome the drawbacks of the prior art described above and to provide a composite billet structure that allows extrusion to begin without leakage of pressure medium between the composite billet and the mandrel. .

A conventional example of manufacturing a composite pipe by the hydrostatic extrusion method is Japanese Patent Application Laid-Open No. 47-31862, which prevents pressure medium from flowing between the billet case and the hollow core, and The purpose is to prevent leakage from the exit of the die, and is not intended to prevent damage to the covering pipe when inserting the mandrel. Other conventional examples of billet hydrostatic extrusion technology include JP-A-48-55167, JP-A-49-63641, and JP-A-57-
No. 11719, etc. are known, but these all relate to extrusion processing of billets made of a single material or a composite material with a coating material provided on the outside of a core material, and inner coating using a mandrel. It is not intended for composite billets for composite pipes.

[Means and effects for solving the problems] This invention has the following features:
The tip of the billet is a substantially conical single metal plug 3, and a coating vibrator 2 is adhered to the rear end surface (i.e., the side with a larger outer diameter) of the plug 3. At this time, the inner diameter of the vibrator 2 is The hollow billet 1 is made larger than the hole for inserting the mandrel 5 in step 3, and the hollow billet 1 serving as a base material is arranged around the covering pipe 2, and welded or brazed between the hollow billet and the covering pipe on the rear end of extrusion. 6' and bonding the stopper 4 to their rear end surfaces to form a composite billet. This prevents breakage and ensures a seal at the plug portion at the tip of the billet.

[Examples] Example 1 A composite billet having the structure shown in FIG. 1 was prepared for extrusion of a Ti tube with an internal Cu coating. That is, the plug 3 at the tip of the composite billet has a truncated conical shape and is made of Cu, and has a diameter of 28 mm at its axis.
It has a hole for inserting a mandrel with a length of 7 am and a length of approximately 50 m.
The rear end has an inner diameter of 31°5, a wall thickness of 0.5m, and a length of 90mm.
A 0 awz Cu tube 2 is welded so that its axis coincides with the axis of the plug hole, and an inner diameter of 33. O size, outer diameter 1
60as+.

One hollow billet made of Ti with a length of 900m+ was installed.

And a CU plug and TIJ billet on the tip side.

The Ti billet on the rear end side and the Cu tube were bonded together by welding 6 and 6', respectively. A tool steel mandrel 5 having an outer diameter of 30.5 mm was inserted into the hole of the composite billet thus produced as shown in FIG.

However, at this time, since the hole diameter of the CU plug 3 was slightly smaller than the diameter of the mandrel 5, the mandrel 5 was forcibly press-fitted into the plug hole using the taper portion formed at the tip of the mandrel 5.

The thus prepared composite billet/mandrel set was placed on a die (not shown) with a hole diameter of 40.5 IIR, and hydrostatic extrusion was performed at an extrusion temperature of 600°C using castor oil as a pressure medium, resulting in approximately 13.0 OOka/ cm2
Outer diameter 40゜5 ttm, wall thickness 5.0M with extrusion pressure of
The Ti tube whose inner surface was coated with Cu could be extruded without any problem.

Example 2 A composite billet having the structure shown in FIG. 1 was prepared for extrusion of a Zircaloy tube whose inner surface was coated with Cu. That is, the plug 3 at the tip of the composite billet has a truncated conical shape and is made of CLJ, and has a hole at its axis for inserting a mandrel 5 with a diameter of 24.71 m and a length of approximately 50 m, and a hole with an inner diameter of 27 m and a wall on its rear end surface. Thickness 0.5
g+, a CLJ pipe 2 with a length of 900rIIIR is welded so that its axis coincides with the axis of the plug hole, and an inner diameter of 29+111. Outer diameter 160IvR.

Zircaloy-2 alloy (1,5% 5n-0) with a length of 900 m
, 15% Fe-0, 10% cr-o, 05% N + - balance Zr). Then, the Cu plug and the Zircaloy-2 alloy billet on the front end side, and the Zircaloy-2 alloy billet and the Cu tube on the rear end side were each bonded by special brazing 6.6-. A tool-forming mandrel 5 having an outer diameter of 25.5jIII was inserted into the hole of the composite billet thus produced as shown in FIG. However, in this case, as in Example 1, the hole diameter of the Cu plug 3 is slightly smaller than the diameter of the mandrel 5, so the mandrel 5 is forcibly press-fitted into the plug hole using the tapered part formed at the tip of the mandrel 5. did.

The thus prepared composite billet/mandrel set was placed on a die (not shown) with a hole diameter of 31.5 JIll, and hydrostatic extrusion was performed at an extrusion temperature of 600°C using castor oil as a pressure medium. g/cm
Extrusion pressure of 2: outer diameter 31゜5 m, inner diameter 3.0 layer m
The Zircaloy-2 tube whose inner surface was coated with Cu could be extruded without any problem.

[Comparative Example 1] A composite billet having the structure shown in FIG. 2 was produced based on a conventional technique for extrusion of a Zircaloy tube whose inner surface was coated with Cu. That is, a hollow billet 1 made of Zircaloy-2 (same composition as above) has a hole diameter of 25.7 in the conical tip 11, a hole diameter of 29 in the layer 9, a hole diameter of 29 in the main body 12, an outer diameter of 160 aw, and a length of 900 a. Diameter 23.5#I1. A Cu tube with a wall thickness of 0.5 layer gr was inserted over the entire length of the billet 1, expanded by a rubber press, and brought into close contact with the inner surface of the hollow billet 1. Special brazing 6 is used to bond CIJ and Zircaloy-2 at the front and rear ends.
．． 6'. A tool steel mandrel 5 with an outer diameter of 25.5 m is inserted into the hole of the composite billet thus prepared as shown in Fig. 2, and then, using a die (not shown) with a hole diameter of 31.5 m, Isostatic pressure extrusion was attempted at an extrusion temperature of 600°C using the pressure medium as a pressure medium, but the pressure medium leaked from between the mandrel/composite billet and extrusion was impossible. Thereafter, when the mandrel 5 was removed and the tip of the composite billet was inspected, cracks had occurred in a portion of the Cu layer.

Therefore, when the hole diameter of the hollow billet tip 11 after cutVB was gradually enlarged, cracks were no longer generated in the Cu tube 2 at a hole diameter of 25.1 m+, but the composite billet provided sufficient restraint at the tip of the mandrel. I can't get strength,
Pressure medium leaked between the mandrel/composite billet and extrusion was impossible.

[Modification] In the above embodiment, a composite billet for hydrostatic extrusion of a composite pipe having a single coating layer 7 on the inner surface was explained, but the present invention has a single coating layer 7 on the inner surface and an outer coating layer 7 on the inner surface as shown in FIG. The present invention is also applicable to a composite billet for hydrostatic extrusion of a composite pipe having a layer 8 or a composite pipe having two coating layers 7-7 on the inner surface as shown in FIG.

[Effects of the Invention] As explained above, according to the present invention, breakage of the inner surface coating pipe when inserting the mandrel is prevented, and therefore, leakage of the pressure medium at the start of extrusion is prevented, and the extrusion success rate is significantly increased. In addition, compared to the composite billet of conventional structure, it is possible to use a thinner walled pipe or a softer material for the inner surface coating pipe.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of a composite billet according to the present invention, Fig. 2 is a sectional view showing a conventional composite billet, and Fig. 3 is a sectional view showing a composite pipe having a single coating layer on the inner surface. 4 are cross-sectional views showing a composite tube having a coating layer on the inner and outer surfaces, and FIG. 5 is a cross-sectional view showing a composite tube having two coating layers on the inner surface. 1...Hollow billet, 11...Tip part. 12... Main body part, 2... Covering pipe. 3...Plug, 4...Stopper. 5... Mandrel, 51... Taper part. 6.6'...Welding or brazing is part. 7.7'...Inner coating layer. 8...Outer surface coating layer. Agent Patent Attorney Fujio Sato 1 Figure % 221 N 3 Figure 4121 12: Salary Department Z S sR / Guardian. 5 Near γ 4 Cost, C 1 S: Masido I Sl: Taper・To 82 External Fine JI Manen 5 Ro

Claims (1)

[Claims] (1) A covering pipe having an inner diameter larger than the hole diameter of the plug is attached to the rear end surface of a substantially conical single metal plug that has a mandrel insertion hole in the shaft center and a tapered surface that fits the extrusion die. Glue on the same axis as the plug,
A hollow billet serving as a base material is arranged around this covering pipe, and an airtight treatment is performed between the hollow billet on the rear end of extrusion and the covering pipe, and a stopper is bonded to the rear end surface of the hollow billet to form an inner coating. Composite billet for isostatic extrusion of composite pipes.