JPS5811314B2 - Method for manufacturing thin-walled metal tubes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for simultaneously manufacturing a plurality of thin-walled metal tubes.

In general, thin-walled metal tubes made of noble metals or noble metal alloys are often used as decorative items or electronic materials.

First, as a method for manufacturing a thin-walled metal tube, the inventor wound a metal plate into a tubular shape, overlapped both ends of the metal plate to form a metal tubular body, and installed this metal tubular body in a pair of upper and lower crimping jigs. We then developed and proposed a method for manufacturing a thin metal tube by heat-pressing the overlapping portions in a non-oxidizing atmosphere and integrating them by diffusion bonding.

With this method, a good product can be obtained when manufacturing one thin-walled metal tube by combining one set of crimping jig and core rod, but in order to improve productivity, multiple thin-walled metal tubes can be manufactured at the same time. When manufacturing, there were the following problems.

For example, it is generally considered that a plurality of the above sets are placed side by side on the lower base of the press and pressed at the same time, but even if each set is made to have exactly the same dimensions, it is possible to Due to variations in the flatness or parallelism of the upper and lower presses, the pressing force applied to each set was uneven, and the resulting crimped parts of each thin-walled metal tube were not uniform. .

There is also a method of stacking each set vertically and crimping them at the same time, but in terms of the press stroke and stability during compression, the stacking is limited to several stages.
No significant improvement in workability could be expected.

In view of the above, as a result of various studies, the present invention has been developed by arranging a plurality of crimping jigs in parallel in the horizontal direction and stacking them in one or more tiers. A pressing piece that has a higher melting point than the metal tubular bodies and is soft at the crimping temperature is placed, and after reaching a predetermined temperature, a pressing force is applied to simultaneously crimp the overlapping portions of multiple metal tubular bodies. As a result, a method for manufacturing a thin metal tube that can form a uniform crimped portion has been discovered.

The method of the present invention will be explained in detail below with reference to the drawings.

As shown in Fig. 1, both ends of the thin metal plate 1 are connected at an angle θ=1
A tapered portion 2.2' is formed by tapering from 0° to 60°.

This taper processing is performed by an appropriate method such as cutting plastic processing or other processing.

Next, this metal plate 1 is formed into a tapered portion 2 as shown in FIG.
．． 2' are overlapped and wound into a tubular shape so as to form an overlapping portion 3, thereby creating a metal tubular body 4.

As shown in FIG. 3, a core frame 5 is inserted inside the metal tubular body 4 obtained in this way, and then this is connected to an upper mold jig 7 provided with a semicircular groove 6 and a lower mold jig. 8 to assemble one set 10.

Note that a plurality of grooves 11 are formed in the soil surface of the upper mold jig 7 along its longitudinal direction.

Further, an upper die jig 7 that constitutes the core frame 5 and the crimping jig 9
The lower die jig 8 is made of a refractory material such as graphite or a heat-resistant metal such as hot work tool steel.

Next, as described above, a plurality of sets 10a, 10b...
After assembling and arranging these horizontally on the lower stand 13 of the press 12 as shown in FIG. Put 15.

The suppressing piece 15 is made of a metal that has a higher melting point than the metal tubular body 4 and is soft at the compression temperature, and the combination thereof is selected as appropriate.

Next, the upper stand 14 of the press 12 is lowered, and each set 10a, 10
(b) Hold it while pressing it lightly.

The thus-combined product is placed in a hot pressing furnace 16 and heated in a non-oxidizing atmosphere.

As this non-oxidizing atmosphere, for example, an inert, neutral or reducing gas such as hydrogen, argon, nitrogen, carbon monoxide, etc. is used.

After heating in the hot crimping furnace 16 and when the crimping jig 9 reaches a predetermined temperature, the upper table 14 of the press 12 is lowered to apply a large pressing force to each set 10a, 10b, etc.
Overlapping portion 3 of metal tubular body 4 inside...
are diffusion bonded and crimped.

Next, the upper stage 14 of the press 12 is stopped, the pressing force is removed, and the press 12 is cooled. After that, the core frame 5 is removed, and a plurality of thin-walled metal tubes are manufactured at the same time.

By inserting the pressing metal pieces 15 and applying pressing force to the crimping jig 9 in this way, even if the height of each pressing piece 15 varies during pressing at the crimping temperature, the pressing pieces 15 can be made of a soft material. Because of this, the metal tubular body 4 is crushed before the metal tubular body 4, and its height becomes almost equal, and each crimping jig 9...
The forces applied to ... are averaged.

Furthermore, since the melting point of the suppressing piece 15 is higher than that of the metal tubular body 4, this state is maintained until the crimping is completed without melting, so that the overlapping portion 3 can be crimped uniformly.

In the above description, the pressing piece 15 is provided on the upper surface of the crimping jig 9, but it may be provided on the lower surface. The groove 11 formed on the top surface does not necessarily need to be provided.

In addition, each set 10a, 1 which combines the crimping jig 9 and the core frame 5
0b... are not limited to those arranged side by side in one row in the horizontal direction, but may be arranged in parallel and stacked in multiple stages.

In this case, the pressing piece 15 is provided on the uppermost surface or the lowermost surface.

Next, examples of the present invention will be described.

Au-Ag-CuZn with a thickness of 0.3 mm as the metal plate 1
An alloy was used, and both ends thereof were cut to form a tapered portion 2.2' with an angle θ=60°.

Next, this metal plate 1 is wound so that the tapered parts 2 and 2' overlap to create a metal tubular body 4 with an inner diameter of 30 mm and a length of 500 mm. inserted.

Next, this is a semicircular groove 6 with a radius of curvature of 15.3 mm.
The set 10 was assembled by inserting it between the upper mold jig 7 and the lower mold jig 6 which had been formed.

The upper mold jig 7 had three linear concave grooves 11 each having a depth of 2rnrIt1 and a radius of curvature of 10 mm and a length of 550 mm formed on the upper surface thereof.

Next, assemble six sets of each of the above sets 10a, 10b, etc., and place them side by side on one press 13 in the horizontal direction, and then insert a copper rod with a diameter of 5 mm and a length of 550 mm into the groove 11. Pressing piece 15 consisting of... is placed on the press 1.
It was held between the base 14 and the lower base 13 of 2.

Next, this is placed in a hot bonding furnace 16 heated to 780°C in a hydrogen gas atmosphere, held for about 2 hours, and then crimped by applying a pressing force of about 50 tons for 30 minutes, and then cooled. Then, the core frame 5 was removed and six thin-walled metal tubes were manufactured at the same time.

The thickness variation of the thus obtained thin-walled metal tube at the crimped overlapping portion 3 is 0.29 to 0.32 m.
m, and even in a tube expansion test in which a conical carving tool with an apex angle of 60° was pushed into one end of a test specimen cut to a length of 50 mm and expanded to an outer diameter of 35 mm, the fracture at the overlapping part 3 was 1. Books were also not accepted.

Furthermore, in order to confirm the effect of the present invention, when six thin-walled metal tubes were simultaneously manufactured in the same manner as above without using the suppressing piece 15, the variation in the thickness of the overlapped portion 3 was 0.27 to 0.3.
It is large at 5mm, and in the tube expansion test, it was rated 2 out of 6.
The book broke at the overlapped portion 3 where it was crimped.

As explained above, according to the method for manufacturing a thin-walled metal tube according to the present invention, by pressing the crimping jig with a suppressing piece interposed, a pressing force is uniformly applied to each crimping jig arranged in parallel, and the crimping jig is pressed. It is possible to simultaneously manufacture a plurality of high-quality products with little variation in the thickness of the overlapped portions and which are firmly joined.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention; Fig. 1 is a perspective view of a tapered metal plate, Fig. 2 is a perspective view of a metal tubular body, and Fig. 3 is a crimping jig and core frame that constitute the set. FIG. 4 is an exploded perspective view of the metal tubular body; FIG. 4 shows a state in which the set shown in FIG. FIG. 1...Metal plate, 2, 2'...Taper part, 3...Overlapping part, 4...Metal tubular body, 5...・Core frame, 6...Groove, 7...
...Upper mold jig, 8...Lower mold jig, 9...
・Crimping jig, 10, 10a, 10b...Set, 12...Press, 13...Lower stand, 14
...Upper stand, 15...Press piece, 16...
...Hot pressure bonding furnace.

Claims (1)

[Claims] 1. Wrap a metal plate so that both ends are overlapped, then insert a core rod inside the metal tubular body, and use a pair of upper and lower crimping jigs to press the overlapped part in a non-oxidizing atmosphere. In the manufacturing method of a thin-walled metal tube in which the core rod is heat-pressed and then the core rod is extracted, a plurality of the crimping jigs are arranged side by side in the horizontal direction and stacked in one or more tiers, and the top or top of the crimping jigs is A pressing metal piece that has a higher melting point than the metal tubular body and is soft at the bonding temperature is placed on one of the lower surfaces, and after reaching a predetermined temperature, a pressing force is applied to form a plurality of metal tubular bodies. A method for manufacturing a thin-walled metal tube, characterized by simultaneously crimping the overlapping parts of the bodies.