JP2004025279A - Deep drawing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a deep drawing apparatus for forming a cylindrical container from a thin metallic sheet, which apparatus performs drawing of a square cylindrical container of a deep bottom by a set of dies and punches. <P>SOLUTION: A blank holder 14 for holding a blank 10 between itself and the die 11 consists of holder segments 14a and 14b having top surfaces of a sectorial shape segmented by eight equal portions around the punch 13 and a pedestal 15 for moving the holder segments 14a and 14b in a diametral direction and having a top surface which is a slope 15a. The holder segments 14a of four pieces one set of every after one piece in a circumferential direction correspond to the rectilinear sides of the container and the holder segments 14b of the remaining four pieces one set correspond to the corners of the container. When the punch 13 presses the blank 10, the holder segments 14a and 14b move cooperatively and alternatively, set by set, to a central direction, thereby feeding the peripheral edge of the blank into a through-hole 12 of the die 11. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a deep drawing apparatus for forming a cylindrical container from a thin metal plate.
[0002]
[Prior art]
In the field of can making, a kind of press forming machine called a deep drawing apparatus is used to form a bottomed cylindrical or bottomed rectangular container from a thin metal plate such as aluminum. FIG. 13 is a schematic view showing a forming procedure using a conventional general deep drawing apparatus.
[0003]
The deep drawing apparatus has a die 11, a punch 13, and a blank holder (wrinkle suppressing plate) 14 as main elements. The punch 13 descends from the state in which the metal sheet 10 to be processed (generally referred to as a blank because it is called a blank) 10 is pressed and held by the die 11 by the blank holder 14 (see FIG. 13A). Thereby, the central portion of the blank 10 is pushed into the through hole 12 of the die 11 (see FIG. 13B). The peripheral portion of the blank 10 is gradually drawn into the through hole 12 with the pressing, and slides while being sandwiched between the blank holder 14 and the die 11. Finally, as shown in FIG. 13 (C), all or most of the peripheral edge of the blank 10 is drawn into the through hole 12 of the die 11, and covers the side peripheral surface of the punch 13 to cover the side wall of the container. Form.
[0004]
[Problems to be solved by the invention]
In such a conventional deep drawing method, it is preferable to increase the pressing force on the peripheral portion of the blank 10 by the blank holder 14 in order to suppress the generation of wrinkles of the blank 10 due to tension. It becomes difficult to slide in the gap between the die 11 and the blank holder 14, and as the punch 13 descends, the plate thickness becomes thinner in a part of the blank 10, especially near the corner of the tip of the punch 13 and near the shoulder of the die 11. Too much, and tears and the like easily occur. Such an effect increases as the advance length of the punch 13 increases. Therefore, for example, when molding a deep-bottom can such as a beer can, a plurality of molds having different diameters of the through hole 12 and the punch 13 are prepared, and the molds are exchanged (or another apparatus is used). Use), the container had to be formed deeper step by step. For this reason, the cost of the apparatus (mold) is large, and the molding time is prolonged, which has been a factor that hinders improvement in manufacturing efficiency.
[0005]
Further, although the conventional deep drawing method corresponds to the molding of a cylindrical container capable of drawing the blank 10 into the through hole 12 substantially uniformly around the punch 13, the bottom shape is, for example, square. It is not suitable for forming a rectangular container. This is because the amount of movement of the blank drawn into the through-hole 12 as the punch 13 descends differs between the corner portion and the right side portion of the rectangular cylindrical container. This is because it easily occurs.
[0006]
The present invention has been made to solve such problems, and a first object of the present invention is to form a cylindrical container more efficiently than before without using many types of dies and punches. It is an object of the present invention to provide a deep drawing apparatus capable of reducing the cost and thus reducing the cost.
[0007]
A second object of the present invention is to provide a deep drawing process that can efficiently perform drawing using not only a cylindrical container but also a rectangular container using one or a small number of dies and punches. It is to provide a device.
[0008]
[Means for Solving the Problems]
In the course of researching the deep drawing method for many years, the present inventors have conducted a lecture on Spring Working on Plasticity in 2001, “Friction Aided Deep Drawing Using Tapered Blank-holder Divided Into Four Segments (a frictional plate using a split type movable friction suppressor). Development of assisted deep drawing method)), a deep drawing machine with a new structure is proposed. In this deep drawing apparatus, the upper annular blank holder is radially equally divided into four, and two holder divided pieces opposed to each other with a punch interposed therebetween are set as one set, and the holder divided pieces are alternately arranged for each set. Move in the inner circumferential direction. Along with the movement, the blank peripheral portion sandwiched between the holder divided piece and the die is actively fed into the through hole of the die. As a result, the blank is smoothly drawn into the through-hole in accordance with the advancement of the punch as compared with the case of using a so-called integrated blank holder, so that an excessive force due to the drawing is less likely to be applied to the blank. It is possible to form some deep containers while using dies and punches.
[0009]
However, in the configuration in which the blank holder is divided into four parts, when one set of opposed holder divided pieces is moved toward the center, the peripheral edge of the blank is outside between the other set of holder divided pieces and the die. It was found to expand in the direction. Therefore, even if the movement of the holder divided pieces is alternately repeated for each set, the efficiency with which the blank peripheral portion is actively fed into the through hole is not necessarily high. As a result, the number of repetitions must be very large, and the processing time is prolonged accordingly.
[0010]
Therefore, in addition to the above-mentioned problems, in order to improve these points, the deep drawing apparatus according to the present invention has a hole-shaped or concave shape in order to form a bottomed cylindrical container from a blank as a material to be molded. A die provided with an outer die, a punch that advances into the outer die of the die, and a blank holder that holds the blank between the die,
The blank holder includes 2n (n is 3 or more) divided pieces in a top fan shape radially divided around the punch,
When the punch is advanced into the outer mold, of the 2n divided pieces, every other n divided pieces in the circumferential direction and the other n divided pieces are each set as one set, Driving means for applying a force to move in the inner circumferential direction alternately for each set is provided.
[0011]
Embodiments and effects of the present invention
In the deep drawing apparatus according to the present invention, for example, when n is 3, the number of divided pieces is six. Therefore, when equally divided around the punch, the opening angle of each divided piece is 60 °. Further, when n is 4, the number of divided pieces is eight. Therefore, when equally divided around the punch, the opening angle of each divided piece is 45 °. That is, the angular width of a portion sandwiched between two adjacent divided pieces of one set of divided pieces (that is, one divided piece of another set of divided pieces) is narrow. . When a certain set of divided pieces moves in the inner circumferential direction by the force applied by the driving means, the blank peripheral portion of the portion directly in contact with the divided pieces moves in the inner circumferential direction. On the other hand, a compressive force is applied from both sides to the blank peripheral portion located at a portion sandwiched between two adjacent divided pieces of the set of divided pieces, but the angular width is narrow as described above. The component of the compression force in the outward direction is small, and therefore, the blank peripheral portion is unlikely to move outward (bulge).
[0012]
Therefore, according to the deep drawing apparatus according to the present invention, the peripheral portion of the blank held between the die and the blank holder is efficiently fed into the outer die of the die, so that a deep-bottomed container can be formed in a shorter time. Can be molded. Further, even when such a deep-bottomed container is formed, good deep drawing can be performed using only one or a small number of dies and punches without requiring many types of dies and punches. Thereby, the manufacturing cost of the cylindrical container can be reduced.
[0013]
Further, the deep drawing apparatus according to the present invention can of course be used when forming a cylindrical container, but is particularly useful when forming a rectangular cylindrical container. . That is, the deep drawing apparatus according to one embodiment of the present invention is a deep drawing apparatus that performs deep drawing of a rectangular cylindrical container having a bottom surface shape of an n-sided shape, wherein the 2n divided pieces of the blank holder are Among them, the n pieces divided every other in the circumferential direction correspond to the corners of the rectangular cylindrical container, and the other n pieces correspond to the straight sides between the corners. can do.
[0014]
According to this configuration, all the right side portions and all the corner portions are alternately and almost simultaneously sent to the outer die in the inner circumferential direction, so that deformation and distortion in the circumferential direction are less likely to occur, and breakage occurs. A deep container can be formed without doing so. Therefore, a deep rectangular tube container can be efficiently formed by combining one type of die and punch.
[0015]
In the deep drawing apparatus of the present invention, the efficiency of feeding the peripheral portion of the blank into the outer mold is improved as the value of n is increased, but on the other hand, the configuration of the blank holder and the driving means is complicated and practical. Disappears. Therefore, n may be set to 4 in one embodiment.
[0016]
【Example】
Hereinafter, a deep drawing apparatus according to an embodiment of the present invention will be described with reference to the drawings. The deep drawing apparatus of this embodiment draws a bottomed rectangular cylindrical container having a substantially square bottom surface.
[0017]
FIG. 1 is a top view of a blank holder of the deep drawing apparatus of the present embodiment. FIG. 2 is a longitudinal sectional view of the deep drawing apparatus taken along line AA 'in FIG. 3A and 3B are explanatory views of the molding operation in the present apparatus, wherein FIG. 3A is a vertical end view taken along the line AA ′ in FIG. 1, and FIG. 3B is a vertical end view taken along the line BB ′. FIGS. 4A and 4B are views showing a state in which the blank peripheral portion is deformed due to the pushing of the blank holder. FIG. 4A shows a pushing state in the right side direction, and FIG. 4B shows a pushing state in the corner direction. In FIGS. 1 to 4, the same or corresponding components as those in FIG. 13 are denoted by the same reference numerals, and description thereof will be omitted unless otherwise required.
[0018]
In the deep drawing apparatus of this embodiment, the blank holder 14 for holding the blank 10 is divided into approximately eight equal parts around the punch 13, and the holder divided pieces 14 a 1 to 14 a 4 and 14 b 1 each having a fan-shaped upper surface shape. 14b4, and a pedestal 15, which is a flat conical inclined surface 15a whose upper surface is annular and whose upper surface is inclined downward from the inner peripheral side toward the outer peripheral side. Guide pieces (not shown) extending radially in the radial direction protrude from the inclined surface 15a of the pedestal 15. The guide pieces are provided in grooves provided on the bottom surfaces of the holder divided pieces 14a1 to 14a4 and 14b1 to 14b4. When the pieces are fitted, the holder divided pieces 14a1 to 14a4, 14b1 to 14b4 are each slidable in the radial direction along the inclined surface 15a.
[0019]
The eight holder divided pieces 14a1 to 14a4 and 14b1 to 14b4 are one set of every other one around the punch 13 and one set of holder divided pieces (hereinafter referred to as 14a1 to 14a4). , 14a) form the right side of the rectangular cylindrical container, and another set of holder divided pieces 14b1 to 14b4 (hereinafter, simply referred to as 14b) has a proper corner. It forms a corner portion of a rectangular cylindrical container having a radius.
[0020]
The two sets of holder split pieces 14a and 14b are configured to be pressed from the outer peripheral side by a drive mechanism (not shown) so as to move in association with the center direction for each set. When one set of holder split pieces 14a or 14b is pressed so as to move in the center direction, the press on the other set of holder split pieces 14b or 14a is released and can be freely moved in the radial direction. It is. Therefore, as shown by, for example, an arrow M1 in FIG. 1, when one set of holder divided pieces 14a moves (forwards) toward the center, another set of holder divided pieces 14b sandwiched between the holder divided pieces 14a. Is pushed to move in the outer peripheral direction (retreat) as shown by the arrow M2 in FIG.
[0021]
As described above, since the holder divided pieces 14a and 14b slide on the inclined pedestal 15, the upper surface of the holder divided piece 14a or 14b that has moved forward rises, and conversely, the holder divided piece 14b or 14a that has receded in the outer peripheral direction. The upper surface sinks. Therefore, in the case of the movement shown in FIG. 1, as shown in FIG. 3A, the upper surface of the holder divided piece 14a (14a2, 14a4 in FIG. It contacts the lower surface and pushes the blank 10 toward the center while giving a strong frictional force. On the other hand, as shown in FIG. 3B, the upper surface of the holder divided piece 14b (14b1, 14b3 in FIG. 3B) which retreats in the outer peripheral direction is separated from the lower surface of the blank 10, and the frictional force against the blank 10 is reduced. It is released.
[0022]
For example, a lubricant having high lubricity is attached to the lower surface of the die 11 so that friction between the die 11 and the blank 10 is reduced as much as possible. Accordingly, the peripheral portion of the blank 10 slides on the lower surface of the die 11 and is fed into the through hole 12 according to the holder divided piece 14a or 14b moving in the center direction.
[0023]
In the deep drawing apparatus of the present embodiment, when the punch 13 advances (in the present embodiment, the ascending operation), the moving operation of the holder divided pieces 14a and 14b as described above is alternately performed, so that the blank 10 is removed from the blank 10. The square cylindrical container is deep drawn. Specifically, when the punch 13 advances and pushes up the blank 10 as shown by an arrow P2 in FIG. 3, four holders located at the right side portion 10a as shown in FIG. The operation of moving the split piece 14a forward (the four holder split pieces 14b located at the corner portion 10b retract) and the four holder split pieces 14b positioned at the corner portion 10b as shown in FIG. The operation of moving forward (the four holder divided pieces 14a located at the right side portion 10a retreat) is alternately repeated. These forward movements positively assist the punch 13 in drawing the blank 10 into the through hole 12.
[0024]
As shown in FIG. 4 (A), the surface of the blank 10 which receives the pushing force (arrow M3 in the figure) by the holder divided piece 14a in the peripheral portion of the blank 10 is almost equal to the holder divided piece 14a due to frictional force toward the center. Displace. On the other hand, in the portion that does not receive the pushing force, a circumferential compressive force by the advancing holder segment 14a and a tensile force by the punch 13 act. When the compressive forces from both sides are combined, a radially outward component is generated. If the tensile force by the punch 13 is larger than this component, the peripheral portion of the blank 10 moves toward the center. In this embodiment, since the opening angles of the holder divided pieces 14a and 14b are relatively small, the radially outward component is small. Therefore, the peripheral portion of the blank 10 in this portion also moves toward the center without fail. At this time, since a wrinkle suppressing force by the holder divided piece 14b does not act on this portion, a slight wrinkle occurs. However, since the wrinkles are sequentially crushed in the process of repeating the pressing, the wrinkles are gradually flattened and eventually almost completely eliminated. In this way, the blank 10 can be squeezed into the through hole 12 of the die 11 while gradually reducing the outer peripheral edge of the blank 10.
[0025]
FIG. 5 is a diagram showing parameters and processing conditions of the deep drawing apparatus of the present embodiment manufactured by the present inventors. FIG. 6 is a diagram showing the results of actually measuring the relationship between the number of times of pressing at each radial position of the peripheral edge of the blank 10 and the amount of displacement toward the center when the rectangular cylindrical container is formed by the present apparatus. When the number of times of pressing is odd, pressing is performed by the holder divided piece 14a in the direction of the right side (on the line AA 'in FIG. 1), and when the number of pressings is even, the direction of corner (on the line BB' in FIG. 1). ) Is pressed by the holder divided piece 14b. The boundary direction is a direction of a straight line where the holder divided piece 14a in the right side direction and the adjacent holder divided piece 14b in the corner direction are in contact with each other.
[0026]
From FIG. 6, it can be seen that in both the right side direction and the corner direction, the displacement is almost equal to the movement amount (1 mm) of the holder divided piece 14 a or 14 b at the radial position at all times of receiving the pushing force. On the other hand, when the number of times of the pressing force is not received, a distribution occurs in the displacement amount, which indicates that the elongation has occurred in the radial direction. Further, the amount of displacement near the shoulder of the die 11 is about 1 mm in the direction of the right side, but is about half that in the direction of the corner. Furthermore, it can be seen that in the boundary direction, the displacement is almost equal to the central component (cos 22.5 ° = 0.92) of the movement amount of the holder divided pieces 14a, 14b regardless of the pushing direction.
[0027]
FIG. 7 is a top view of the blank 10 when pushing is repeated many times, and FIG. 8 is a perspective view of a rectangular cylindrical container formed from the blank 10. In order to make it easier to check the deformation state of the blank 10, a radial scribing line with a 22.5 ° interval in the circumferential direction and a concentric scribing line with a 2mm interval in the radial direction are inserted into the blank 10. FIG. 9 shows the state of the scribe line on the container side wall after molding.
[0028]
From the situation of the displacement amount as described above, when the alternate pushing of the right side direction and the corner direction is repeated, the displacement amount in the boundary direction becomes larger than other portions, and as a result, the peripheral portion of the blank 10 Are formed with eight ears 10c.
[0029]
On the other hand, it can be seen from FIG. 9 that the amount of inflow into the through hole 12 in the boundary direction between the holder divided pieces 14a and 14b is larger than in the other portions. Since the scribe line in the boundary direction is substantially parallel to the scribe lines in the right side direction and the corner direction, the circumferential movement of the blank 10 across the boundary direction hardly occurs. It can be seen that the deformation of the blank 10 is appropriately regulated by the pressing by the divided pieces 14a and 14b.
[0030]
According to the experiments by the inventors, it is possible to easily form a bottomed rectangular cylindrical container having a height (depth) equivalent to twice the length of the opposite side as shown in FIG. 8 using the deep drawing apparatus according to the present embodiment. Was able to be obtained.
[0031]
Although the above embodiment is a deep drawing apparatus for forming a rectangular cylindrical container, it is useful to make the number of divisions of the blank holder 14 about 8 or more even when forming a cylindrical container. This will be described next.
[0032]
FIG. 10A is a top view showing an eight-part blank holder 14 for forming a cylindrical container, and FIG. 10B is a top view showing a four-part blank holder 14. FIG. 11 shows the relationship between the number of presses at each radial position of the peripheral portion of the blank and the amount of displacement in the center direction when forming a cylindrical container with a deep drawing apparatus using an eight-piece blank holder. FIG. 12 is a view showing a result, and FIG. 12 is a view showing a similar actual measurement result at the time of forming a cylindrical container in a deep drawing apparatus using a four-piece blank holder.
[0033]
From FIGS. 11 and 12, in both the AA ′ direction and the BB ′ direction, the displacement is almost equal to the moving amount (1 mm) of the holder divided piece 14a or 14b at the radial position at all times of receiving the pushing force. You can see that it is doing. On the other hand, there is a great difference between the eight-piece blank holder and the four-piece blank holder in the displacement amount at the time of not receiving the pushing force.
[0034]
That is, in the four-divided blank holder, in both the AA 'direction and the BB' direction, the displacement amount is negative on the outer peripheral side of 24 mm when the number of times of receiving the pushing force is not received. This means that it has been displaced outward (ie, expanded) before receiving the pushing force of that time. The reason is that, in a four-piece blank holder, since the opening angle of one holder piece is large, a radially outward component of the combined force of the compressive forces received from both sides becomes large. Therefore, for example, even if the pressing force is displaced in the center direction by 1 mm at the time of receiving the pushing force, it is displaced outward by 0 to 0.4 mm at the number of times the next pushing force is not received. By the alternate pushing operation, the pushing effect can be obtained only about 0.6 mm at the worst. On the other hand, in the eight-piece blank holder, it can be seen that the displacement amount remains positive even when the number of times the push-in force is not applied, and the blank holder surely advances toward the center. That is, this difference appears as a difference in efficiency during molding.
[0035]
Therefore, in the case where the eight-piece blank holder is used, the number of times of repeated press-in required for molding a cylindrical container having the same height is smaller than that in the case where the four-piece blank holder is used, and the time is shorter, that is, The cylindrical container can be drawn at low cost.
[0036]
It should be noted that each of the above embodiments is merely an example of the present invention, and it is apparent that modifications and additions can be made as appropriate within the spirit of the present invention.
[Brief description of the drawings]
FIG. 1 is a top view of a blank holder in a deep drawing apparatus according to one embodiment of the present invention.
FIG. 2 is a vertical sectional view of the deep drawing apparatus of the present embodiment taken along line AA 'in FIG.
3A and 3B are explanatory views of a forming operation in the deep drawing apparatus of the present embodiment, wherein FIG. 3A is a vertical end view taken along line AA ′ in FIG. 1, and FIG. Vertical end view.
4A and 4B are diagrams showing a state of deformation of a peripheral portion of a blank due to pushing of a blank holder, wherein FIG. 4A shows a state of pushing in a right side direction, and FIG. 4B shows a state of pushing in a corner direction.
FIG. 5 is a diagram showing parameters and processing conditions of the deep drawing apparatus of the present embodiment.
FIG. 6 is a diagram showing the results of a measurement of the relationship between the number of times of pressing at each radial position of the blank peripheral edge and the amount of displacement toward the center when forming a rectangular cylindrical container by the deep drawing apparatus of the present embodiment.
FIG. 7 is a top view of the blank when the indentation is repeated many times using the deep drawing apparatus of the present embodiment.
FIG. 8 is a perspective view of a rectangular cylindrical container formed from a blank using the deep drawing apparatus of the present embodiment.
FIG. 9 is a view showing a state of a scribe line on a container side wall after molding.
FIG. 10A is a top view showing an eight-piece blank holder for forming a cylindrical container, and FIG. 10B is a top view showing a four-piece blank holder.
FIG. 11 shows the results of a measurement of the relationship between the number of presses at each radial position of the peripheral edge of the blank and the amount of displacement toward the center when forming a cylindrical container with a deep drawing apparatus using an eight-piece blank holder. FIG.
FIG. 12 is a diagram showing the same actual measurement result when forming a cylindrical container in a deep drawing apparatus using a four-piece blank holder.
FIG. 13 is a schematic diagram showing a forming procedure using a conventional general deep drawing apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Blank 10a ... Right side part 10b ... Corner part 11 ... Dice 12 ... Through hole 13 ... Punch 14 ... Blank holder 14a, 14a1-14a4, 14b, 14b1-14b4 ... Holder split piece 15 ... Base 15a ... Inclined surface

Claims (3)

A die provided with a hole-shaped or concave-shaped outer die for forming a bottomed cylindrical container from a blank which is a material to be formed, a punch extending into an outer die of the die, and the die And a blank holder sandwiched between
The blank holder includes 2n (n is 3 or more) divided pieces in a top fan shape radially divided around the punch,
When the punch is advanced into the outer mold, of the 2n divided pieces, every other n divided pieces in the circumferential direction and the other n divided pieces are each one set, A deep drawing apparatus comprising: a driving unit that applies a force to move in the inner circumferential direction alternately for each set. What is claimed is: 1. A deep drawing apparatus for performing deep drawing of a rectangular cylindrical container having an n-sided bottom surface, wherein every other n pieces in the circumferential direction among the 2n pieces of the blank holder. 2. The deep drawing apparatus according to claim 1, wherein は corresponds to a corner portion of the rectangular cylindrical container, and the other n divided pieces correspond to a right side portion between the corner portions. 3. The said n is four, The deep drawing apparatus of Claim 1 or 2 characterized by the above-mentioned.

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