JPH01138075A - Manufacture of welded can barrel - Google Patents

Abstract

PURPOSE:To weld a can barrel at a relatively high speed by performing high-frequency induction heating on a lap of a can barrel preform at the temperature capable of solid phase welding. CONSTITUTION:The can barrel preform 2 is transferred intermittently at the prescribed speed in the A direction with the rear end face being pushed by a finger 4 along a mandrel 1 while holding a shape by a holding roll device 5 and a guide body 7. After the lap 2a is then adhered closely slightly by pressing rolls 11, the lap 2a is passed through the upper part of an induction heating coil 12 and while the lap 2a being induction-heated at the temperature capable of solid phase welding and the shape being maintained by a guide roll 13, the lap 2a is pressed at the prescribed pressure by a pressing roll 14 to form a welded zone.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a welded can body used for cans such as carbonated beverage cans, beer cans, juice cans, coffee cans, and the like.

(Prior art) As a method for manufacturing welded can bodies from metal blanks such as tin-plated steel sheets, recently, the overlapped portions of can body preforms formed from metal blanks are connected to a pair of opposing electrodes via copper wire electrodes. The most commonly used method is to perform electric resistance mano seam welding by applying pressure and applying electricity using an electrode roll.

The reason for using a wire electrode is that when the overlapping part comes into direct contact with an electrode roll made of metal (usually a copper alloy) without using the wire electrode, molten metal such as tin on the surface of the overlapping part will be removed during welding. This is because the metal adheres to the electrode surface of the electrode roll and forms an alloy, staining the electrode surface and requiring frequent replacement of the electrode roll, which interrupts welding work and reduces production efficiency.

By using wire electrodes, the above drawbacks can be overcome, but
Since the other side wire electrode can usually be used only once, there is a problem in that it becomes a consumable item and increases production costs. If the welding speed is further increased, slipping occurs between the wire electrode and the overlapping part, causing defects in the welded part due to slip marks, making it difficult to produce at high speeds of more than approximately 500 cans/min. was there.

In addition, if the wire electrode is a regular one and the blank is made of tinted steel, it is necessary to remove the surface treatment coating on the edge to be welded in advance, which reduces productivity. there were.

(Problems to be Solved by the Invention) An object of the present invention is to provide a method for manufacturing a welded can body that has relatively high production efficiency, relatively low production cost, and can be produced at relatively high speed. shall be.

(Means for Solving the Problems) The method for manufacturing a welded can body of the present invention includes forming a can body preform having an overlapping portion by overlapping opposing edge portions of metal blanks, and forming the can body sill form. The overlapping portions are brought into close contact while shifting in the axial direction, and the overlapping portions are heated by high frequency induction to a temperature that allows solid state welding, and the heated overlapping portions are bonded to a pair of opposing ceramic It is characterized by solid phase welding by pressing with a pressure roll made of.

It is preferable that the overlapping portions be brought into close contact with each other lightly. This is to provide a surface resistance to the bonding surface to produce a skin effect of high frequency current.

Here, the solid state weldable temperature is approximately 900 to
1300°C, more preferably about 950-1100°C.

The ceramic used to form the suppression roll is dense silicon carbide (SiC) with a hardness (HRA) of 92 or more and a bending strength of 5000 kg 7 cm or more, which has excellent wear resistance and relatively high thermal conductivity. , is preferably used because it has a large water cooling effect. Note that the overlapped portion includes the case where both end edges are slightly separated in the radial direction due to the influence of springback.

(Function) The overlapped portions of the can body silifomes are preferably lightly brought into close contact, and high-frequency induction heating is applied to the overlapped portions to a temperature at which solid phase welding is possible, so that the overlapped portions are rapidly raised to a temperature at which solid phase welding is possible. Therefore, welding can be performed at a relatively high speed.

The heated overlapping portions are pressed by a pair of opposing ceramic pressing rolls to solid state weld. Unlike metal rolls (mainly copper alloy rolls), ceramic rolls are not alloyed with low melting metals such as tin during welding. Therefore, even without intervening a wire electrode between the overlapping parts, there is no fear of contamination with tin or the like, and the wear resistance is excellent, so it can be used continuously for a long period of time. Therefore, relatively high production efficiency and relatively low production costs can be achieved. Furthermore, heating and suppression are separated,
When suppressing, current is applied in a direction perpendicular to the overlapping portion to heat the overlapping portion by electrical resistance. Therefore, even in the case of a metal blank made of a surface-treated steel sheet that has a surface-treated film with relatively high electrical resistance, such as Tin + IJ-Steel (electrolytic chromic acid treated steel sheet), this film prevents the electrical conduction of the overlapped portion. As a result, there is a risk that defective welds such as burnt parts or areas with poor welding strength will occur. Therefore, it can be satisfactorily applied to can bodies made of surface-treated steel sheets such as Tinkley steel.

(Example) In Fig. 1, 1 is a mandrel.
A roll forming machine (not shown) disposed on the right side of the sheet is used to form an overlapping portion 2a formed by overlapping opposing edges of a rectangular metal blank (for example, made of a tin-plated steel plate, not shown). The can body preform 2 is attached to the feed rod 3 with the overlapping portion 2a at the top, and its rear end surface is pushed by the finger 4 biased by the spring 6 (see FIG. 2).
The material is intermittently transferred along the mandrel 1 in the direction of arrow A at a predetermined speed.

5 is a holding roll device, as shown in FIG. 2, free rotating rolls 5 a , 5 b , 5 c p 5 d
r 5 e + 5 f and 5 g, and has the function of holding the shape of the preform 2 against springback. Note that at the stage of passing through the holding roll device 5, both end edges 2a and 2a2 of the overlapping portion 2a are slightly separated in the radial direction.

Reference numeral 7 denotes a guide body, which, as shown in FIG. 3, is provided with a pair of opposing half-cylindrical pressers 7a and 7b.

The inner surfaces of the pressers 7a, 7b have a shape corresponding to the outer surface of the mandrel 1, and the pressers 7a, 7b have a spring 8.
The Noriform 2 is connected to the mandrel 1 through the rod 9.
The structure is such that the shape of the Noriform 2 can be maintained until just before welding.

Note that 10 is a holder fixed to a frame (not shown). Reference numeral 11 denotes a presser roll for lightly bringing the overlapped portions 2a into close contact with each other, and is configured to maintain this close contact until the overlapped portions 2a pass directly under the high-frequency induction heating coil 12, which will be described later. ing. Note that the front end side (downstream end side in the traveling direction of the f'J form 2) of each of the pressers 7a, 7b extends to a position where the front end portions 7a, 7b approach a guide roll device 13, which will be described later, as much as possible.

The guide roll device 13 is used to maintain the shape of the preform 2 during welding, and as shown in FIG.
A pair of opposing rotatable side rolls 13a and 13
b1 and a rotatable bottom roll 13c. The side roll 13a has a coaxial upper roll 13a1, an intermediate roll 13a2, and a lower roll 13a3, and the side roll 13b also has a coaxial upper roll 13b5, an intermediate roll 13b2, and a lower roll 13b3. Upper end of upper roll 1.3al, 13b, "a1'+
13 b1' extends to a position as close to the overlapping portion 2a as possible in order to facilitate the close contact of the overlapping portion 2a.

Reference numeral 14 denotes a pressure roll for welding (so-called forge welding) by pressing the overlapping portion 2a, which is induction-heated to a solid state weldable temperature by the high-frequency induction heating coil 12. It has become. The inner roll 14b has a groove 15 (
It is preferable to use ceramics to avoid induction heating (see FIG. 5).

The outer roll 14a has a relatively thin peripheral disk portion 14a.
1 and a relatively thick central portion 14a2. As shown in FIG. 4, the outer roll 14a is rotatably supported by a fixed shaft 16 at a central portion 14a2. The fixed shaft 16 is biased by a spring (not shown) so that the upper roll 14a presses the overlapping portion 2a.

The fixed shaft 16 is formed with guide holes 16a, 16b extending in the axial direction, and side holes 1.6c, 16d extending in the radial direction.
, the annular groove 17 formed in the central portion 14a2, the side hole],
6 d and the guide hole 16 b in the direction of the arrow, and is configured to cool the peripheral disk portion 14 a 1 whose temperature increases due to heat conduction from the overlapping portion 2 a during welding. The number 19 is Iku Nuru.

As shown in FIG. 4, FIG. 5, and FIG. (Made of steel pipes through which cooling water flows)
1.2a and 12a2, as well as upper Q-ibs 12b1 and 12b2, which similarly face each other with the peripheral disk portion 14a1 in between, and the lower @ pipes 12a, 1.
2a2 and upper no, Q Eve 12b,.

12b2 so that high frequency direct current flows in the same direction.

Lower pipe 12a, 12a2 and upper pipe 12
b, 12b2 are surrounded by a ferrite core 20 to increase induction heating efficiency, and are connected to a high frequency power source (not shown) via a bus bar 21. Lower part/yai f
Since current flows in the same direction through 12a and 12a2, a magnetic flux 22 is formed around them, and the pressure roll 14
Immediately before and during pressing by
An induced current flows through the portion, and the portion of the overlapping portion 2a is heated to a temperature that allows solid state welding.

A welded can body is manufactured using the above apparatus as follows. A can body preform 2 (thickness is, for example, 02 mm, inner diameter is, for example, 52 mm) is shaped along the mandrel 1 by the holding roll device 5 and the guide body 7 in the direction of arrow A with its rear end surface being pushed by the fingers 4. While being held at a predetermined speed (
800 cans/min) intermittently. Then, after the overlapping part 2a (overlapping width is, for example, 0.3 to 0.5 mm) is lightly brought into close contact with the presser roll 11, the overlapping part 2
a passes below the induction heating coil 12 (with an output of, for example, 4 kW), and the overlapping portion 2a is induction heated to a solid phase weldable temperature, preferably about 950 to 1100°C.
While the shape is maintained by the guide roll 13, a predetermined pressing force (for example, 100 kg) is applied by the pressure roll 14.
The welded portion 23 is formed by W pressing and welding, preferably by manosh welding. Note that during induction heating, it is preferable to spray an inert gas such as nitrogen gas onto the overlapping portion 2a to prevent oxidation. It is preferable that the thickness of the welded portion 23 is approximately 1.2 to 15 times the thickness of the blank plate. 24 (FIG. 1) is a welded can body having the welded portion 23 formed in this manner.

The high-frequency induction heating coil may be disposed as shown by the reference numeral 26 in FIG. 7, just across the outer roll 14a and at the rear thereof so as to approach the overlapping portion 2a. In this case, for example, as shown in No. 8M, the lower part/guive 26a, 26a2, 26a where the current flows in the same direction.
3 are arranged in an inverted triangular cross section so that the lowermost coil 26a1 is located directly above the overlapped portion 2a, thereby increasing the induction heating efficiency for the overlapped portion 2a. Furthermore, 26b.

26b2 and 26b3 are upper pipes, 27 is a ferrite, and 28 is a bus bar. 30 is still ferrite 2
This is a cooling tube in which cooling water flows through the inside of the cooling tube 7 to cool it through the copper plate 29.

In this case, during the pressing by the pressing rolls 14a and 14b,
Although the overlapping portion 2a is not heated, the induction heating efficiency is high, so the transfer speed of the preform 2 is increased (for example, 80
m/min), so even when suppressed, the overlapping part 2
a can be maintained at a temperature that allows solid state welding.

(Effects of the Invention) The method for manufacturing a welded can body of the present invention has the following effects: production efficiency is relatively high, production cost is relatively low, and production can be performed at relatively high speed.

Furthermore, it has the advantage that it can be satisfactorily applied to can body preforms made of surface-treated steel sheets with relatively high electrical resistance, such as tin-free steel.

[Brief explanation of the drawing]

FIG. 1 is an explanatory front view of an example of an apparatus for carrying out the present invention, and FIGS. 2, 3, and 4 are lines ■-II, flT-III, and ■- in FIG. 1, respectively. FIG. 5 is a partially cutaway front view of the main part of the device in FIG. 1 near the suppression roll; FIG. 6 is a vertical cross-sectional view taken along line IV; FIG.
FIG. 7 is a side view of the high-frequency induction heating coil seen from the l-line side, FIG. 7 is a front view of the main part of the vicinity of the suppression roll of another example of the device for carrying out the present invention, and FIG. 8 is FIG. FIG. 2. Can fitting preform, 2a. Overlapping part, 2a,
, 2a2 - Edge portion, 12.26... High frequency induction heating coil, 14... Press roll, 14a... External roll, ], 4 b... Inner roll, 23... Welding part,
24...Welded can body Fig. 6 Fig. 8

Claims (1)

[Claims] (1) Opposing edge parts of metal blanks are overlapped to form a can body preform having an overlapping part, and while the can body preform is moved in the axial direction, the overlapping part is brought into close contact with each other, The overlapping portion is subjected to high-frequency induction heating to a temperature that allows solid state welding, and the heated overlapping portion is pressed by a pair of opposing ceramic press rolls to perform solid phase welding. A method for manufacturing a welded can body.