JPS625689B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a re-drawing and ironing forming device, and more particularly, to a re-drawing and ironing device that prevents the ear portion from being stretched thinly and causing broken pieces at the end of the re-drawing process of the draw cup. This invention relates to a drawing-iron forming device.

Drawn can bodies, which have recently become widely used for carbonated beverage cans and beer cans, are usually made by drawing and forming a cup from a metal blank such as an aluminum alloy plate or tin-plated steel plate, and then re-drawn. - Formed by redrawing and ironing in two or three stages in one stroke using an ironing device. Due to re-drawing, the diameter of the cup becomes slightly smaller (i.e., the inner diameter becomes equal to that of the drawn-iron can body) and the height becomes slightly larger, but in order to prevent wrinkles from forming on the bottom surface during this process, Normally, the inner peripheral edge of the bottom of the cup is pressed by fluid pressure between a presser pad and the surface of a redrawing die to perform redrawing.

At the end of this re-drawing process, excessive pressure is applied to the ears of the cup (usually 4 to 6 are generated along the circumference during the drawing process due to the anisotropy of the metal plate). is especially thinly stretched,
It is likely to be torn off from the cup body and become broken pieces, resulting in so-called ear cuts. It often happens that the next cup is machined with these fragments attached to the tool, but in that case the fragments are embedded in the body wall of the cup, and during the ironing process, the body wall in which the fragments were embedded is The portion becomes extremely thin, and the tension associated with the ironing process tends to cause problems such as small holes or complete rupture of the body wall in the circumferential direction.

It is an object of the present invention to solve the problems of the prior art described above.

To achieve the above object, the present invention provides a redrawing and ironing forming apparatus for forming an ironed can body from a drawing cup, which is equipped with a redrawing die and a plurality of ironing dies, and the apparatus comprises a redrawing die holding ring and a plurality of ironing dies. A die set in which a plurality of ironing die holding rings are stacked on the side surface of a fixed plate via a plurality of spacers, with the redrawing die holding ring positioned at the outermost side, and the end face of the redrawing die holding ring is an annular piston disposed in contact with and surrounding the die set for pressing the die set and tightening it against the fixing plate; a cup holder capable of pressing the bottom inner periphery of the cup placed in contact with the redrawing die; pad, and a plurality of pins of a predetermined length fixedly attached to the annular piston and extending in the axial direction of the die set, the predetermined length being fixed to the annular piston and extending in the axial direction of the die set. , the gap g between the free end surface of the pin and the flange of the cup holding pad is determined to satisfy the following formula (1), g=t-w (1) where t is The thickness of the bottom of the drawing cup before re-drawing, w is a predetermined value smaller than t, and at least at the end of the re-drawing process, the free end surface of the pin engages with the flange part of the cup holding pad, and the re-drawing process is performed. The present invention provides a re-drawing and ironing forming apparatus characterized in that the clearance between the re-drawing die and the cup holding pad is prevented from becoming smaller than the predetermined value (w).

The present invention will be described below with reference to drawings showing embodiments.

In FIGS. 1 and 2, 1 is a die set, which includes a retaining ring 3 of the re-drawing die 2, a first spacer 4, a retaining ring 6 of the first ironing die 5,
Second spacer 7, holding ring 9 of second ironing die 8, third spacer 10, third ironing die 11
It mainly consists of a retaining ring 12. 13
1 is a nozzle for the cooling lubricant 14, and 15 is a discharge hole for the cooling lubricant jetted from the nozzle 13.
As shown in FIG. 3, the die set 1 is placed on two rails 17 fixed to a housing 16, and is pressed by a leaf spring 19 fixed to a lid 18 hinged to the housing 16. It is supported by 3 points. 20 is a base plate on which the die set 1 is stacked, and the housing 1
A stripper 21 (a stripper 21 having a claw portion (not shown) is fixed to
0) is stored.

23 is a cylinder plate, and bolt 2
4 to the housing 16. An annular air cylinder 25 is formed in the cylinder plate 23 along the flange portion 3a of the redrawing die holding ring 3, and as shown in FIGS. 2 and 4, an annular piston 26 is formed in the air cylinder 25. is housed so as to be in contact with the end surface 3a' (see FIG. 5) of the flange portion 3a. Note 27
is an O-ring. Reference numeral 28 denotes a conduit which supplies pressurized air to the air cylinder 2 through a conduit (not shown).
Supply to 5. Each retaining ring 3, 6, 9, 12 and each spacer 4, 7, 10 is pressed against the base plate 20 by an annular piston operated by pressurized air in an air cylinder 25. is tightened. To remove or install the retaining ring or spacer for replacement or repair, open the lid 18 and open the air cylinder 25.
By releasing the fastening of the annular piston 26 by removing the air pressure, this can be done much more easily than in the case of conventional fastening using bolts or the like.

A plurality of (three in the figure) pins 29 of a predetermined length are fixed to the annular piston 26 by bolts 30 so as to extend in the axial direction of the die set 1. The function of the pin 29 will be described later.

A cup holder 31 is fixed to the cylinder plate 23 with bolts 35. As shown in FIGS. 1 and 5, the drawing cup 32 to be redrawn has a short halved cylindrical shape with the feed side A open, and its inner diameter is the same as that of the drawing cup 32.
It is determined to be approximately equal to the outer diameter of 2. Reference numeral 33 designates a nozzle for injecting the cooling lubricant 34 onto the outer surface of the side wall of the throttle cup 32. As clearly shown in FIGS. 1 and 5, the outer surface 23a of the feed side A of the drawing cup 32 of the cylinder plate 23 is connected to the outer surface 3b of the re-drawing die holding ring 3 (the outer surface 2a of the re-drawing die 2). (on the same plane). Therefore, the drawing cup 32 is smoothly fed. Note that in order to simplify the structure of the re-drawing die holding ring 3, when the outer surface 2a of the re-drawing die and the outer surface 3b of the re-drawing die holding ring are aligned with the end surface 3a' of the flange portion 3a, the drawing cup 32 When approaching the drawing die 2, it is in a floating state in the axial direction, so the drawing cup 32 may jump, shift its center, and be crushed by a presser pad 43, which will be described later. However, in the case of this embodiment, there is no such fear.

Note that the aperture cup 32 is connected to the cage 36 (Fig. 1).
After being guided down by gravity from the upper part in the direction of arrow B and reaching the positions shown in FIGS. It will be placed.

The punch 40 is fixed to the tip of a ram 41, and the ram 41 is reciprocated in the axial direction by a crank mechanism (not shown). A guide hole 42 passes through the punch 40 and the ram 41, and pressurized air is constantly blown out from the tip of the punch through the guide hole 42. The pressurized air is sent to facilitate the removal of the can body from the punch 40 in the stripper 21 after the ladder forming is completed.

Reference numeral 43 denotes a hollow cylindrical presser pad for preventing wrinkles from forming on the drawing cup 32 during redrawing, and its inner diameter is slightly larger than the outer diameter of the punch 40 and the outer diameter is the same as that of the drawing cup 32. It is determined to be slightly smaller than the inner diameter. The presser pad 43 is connected to the annular air cylinder 4 via its flange portion 43a.
It is fixedly installed on the sliding portion 44a of No. 4. The support portion 44b of the annular air cylinder 44 is a support wing 45.
The sliding part 44a is fixed to the supporting part 44b.
It is configured to be slidable along the bushing 46 of. Inside the annular air cylinder 44, there is a guide hole 47.
Pressurized air is supplied through a conduit, not shown. The support wing 45 is reciprocated in the axial direction at a predetermined timing by a cam mechanism (not shown) driven by a crank mechanism (not shown) that drives the ram 41.

The height of the pin 29 is the outer surface 2a of the redrawing die 2.
The clearance between the tip surface 43b of the presser pad 43 is a predetermined value w, preferably approximately (0.5 to 0.9)×
t (where t = thickness of the bottom of the drawing cup 32), the end surface 29a of the pin 29 engages with the flange portion 43a of the presser pad 43, so that the clearance does not become smaller than the predetermined value w. stipulated in Therefore, at the end of the re-drawing process, the ear portion 32a (see FIG. 5) of the drawing cup 32 does not become thinner than approximately (0.5×0.9)×t, thereby preventing the generation of broken pieces. Furthermore, by setting the height of the pin 29 as described above, the clearance will not become larger than the thickness t of the bottom of the aperture cup 32 due to the engagement between the pin 29 and the flange portion 43a. It is possible to make full use of the wrinkle pressing force of 43.

Using the above-described apparatus, re-drawing and ironing, particularly re-drawing, is carried out as follows.

The drawing cup 32, which has first been lowered by gravity through the cage 36 shown in FIG. 1, is placed on the drawing die 2 again by the shuttle 37. At this point, the tips of the punch 40 and presser pad 43 are positioned to the right of the cup holder 31 so as not to interfere with the feeding of the drawing cup 32, as shown in FIG. Next, the support wing 45 advances to the left in the figure, and the tip end surface 43b of the presser pad 43 comes into contact with the inner surface of the throttle cup 32, and the annular air cylinder 44
The inner surface is pressed by air pressure (state shown in FIG. 2). At this point, the pin 29 and flange part 4
3a, there is a gap g of (tw), that is, a gap of approximately (0.1 to 0.5)×t. Next, the punch 42 moves to the left in the figure to perform re-drawing, and when the thickness of the re-drawn cup near the ear 32a reaches a predetermined value w, or when the re-drawn cup (not shown) After passing through the re-drawing die 2, the end surface 29a of the pin 29 and the flange portion 43
a is engaged. Therefore, the ear part 3 of the aperture cup 32
2a is never stretched thinner than the predetermined value w. After that, ironing process is performed.

The advantages of fixing the pin 29 directly on the annular piston 26 are as follows. Due to die wear or damage, the die retaining rings 3, 6, 9, 1
2 and spacers 4, 7, and 10 are often replaced. However, since the dimensional accuracy of the thickness of each retaining ring and spacer is approximately 0 to +0.02 mm, the thickness of the entire die set 1 is approximately +0.02 x 7 mm (7 mm) at maximum.
is the total number of retaining rings and spacers) = +0.14mm
This causes variations in The pin 29 is the annular piston 2
6, this variation does not affect the clearance between the outer surface 2a of the redrawing die and the tip surface 43b of the presser pad when the pin 29 and flange 43a are engaged. However, when the pin 29 is fixed to the housing 16, the cylinder plate 23, or the cup holder 31, the above-mentioned variations directly affect the above-mentioned clearance. However, the thickness t of the bottom of the drawing cup 32 is typically about 0.3 to 0.4 mm. Therefore, when the thickness t = 0.3 mm, the above clearance is set to 0.3 mm x 0.5 = 0.15 for a specific die set 1.
If it is set to mm, when the die set is replaced, there is a possibility that the above-mentioned clearance becomes 0.15 mm - 0.14 mm = 0.01 mm due to the above-mentioned variation. If the clearance is small like this, a problem arises in that the ear portion 32a of the aperture cup 32 extends thinly, resulting in broken pieces (so-called ear breakage).

In the device of the present invention, the die set is fastened by the annular piston, so the die holding ring and spacer can be easily replaced, and the clearance between the redrawing die and the presser pad is smaller than a predetermined value. Since the pin for preventing this is fixed to the annular piston, even if the thickness of the die set as a whole changes due to the above exchange, there is no risk of the edge of the draw cup being cut.

[Brief explanation of the drawing]

FIG. 1 is a side view of the inlet side of the re-drawing and ironing die part of an embodiment of the apparatus of the present invention, FIG. 2 is a longitudinal cross-sectional view taken along the line - in FIG. 1, and FIG. 3 is a - in FIG.
4 is a longitudinal sectional view taken along the - line in FIG. 2, and FIG. 5 is a longitudinal sectional view taken along the - line in FIG. 1. 1... Dice set, 2... Re-drawing die, 3
... Re-drawing die holding ring, 20 ... Base plate (fixed plate), 26 ... Annular piston, 29 ... Pin, 29a ... End face, 32 ... Drawing cup, 43 ... Presser pad, 43a ... Flange part .

Claims (1)

[Claims] 1. A redrawing and ironing forming apparatus for forming a can body ironed from a drawing cup, which is equipped with a redrawing die and a plurality of ironing dies, the apparatus comprising:
A die set consisting of a re-drawing die holding ring and a plurality of ironing die holding rings stacked on the side surface of a fixed plate with the re-drawing die holding ring positioned at the outermost side via a plurality of spacers, the re-drawing die holding ring. an annular piston disposed around the end surface of the die holding ring for pressing the die set and tightening it against the fixing plate; a bottom inner peripheral edge of the cup placed in contact with the redrawing die; and a plurality of pins of a predetermined length that are fixed to the annular piston and extend in the axial direction of the die set, and the predetermined length is such that the cup presser pad is able to press the inside surface of the bottom of the cup. The gap g between the free end surface of the pin and the flange of the cup holding pad is determined so as to satisfy the following formula (1), g=tw......( 1) Here, t is the thickness of the bottom of the drawing cup before re-drawing, w is a predetermined value smaller than t, and at least at the end of the re-drawing process, the free end surface of the pin engages with the flange of the cup holding pad. hand,
A re-drawing and ironing forming apparatus characterized in that a clearance between the re-drawing die and the cup holding pad is prevented from becoming smaller than the predetermined value (w) during the re-drawing process.