Patent Application
20120266644
This application claims the priority of German Application No. 10 2011 002 206.6-14 filed Apr. 20, 2011.
The present invention relates to a device and to a method for manufacturing a can body which is used in particular for manufacturing an aerosol can. The can body to be manufactured has a cylindrical wall section adjoined by a neck section with a lower diameter when compared with the cylindrical wall section, where the neck section preferably has a cylindrical end section. This can body is then used as a semi-finished part for the manufacture of an aerosol can.
The manufacture of an aerosol can is subject to conflicting aims. On the one hand the aerosol cans of different manufacturers should stand out from each other, which can lead to increased material and cost expenditure, and on the other hand low material consumption and low weight are required for cost reasons and in particular for environmental reasons. In comparison with beverage cans, the required quantities of the aerosol cans are however considerably lower, so that the same economies of scale as with beverage cans cannot be achieved. Complex and expensive manufacturing devices that have proven themselves for the manufacture of beverage cans cannot therefore be readily transposed to a device for manufacture of an aerosol can.
U.S. Pat. No. 5,357,779 describes for example a so-called “body maker” used for manufacturing a can body, where a workpiece with a bottom and an adjoining cylindrical wall is made from a pre-formed cup by ironing. A narrowed section cannot be achieved with this device.
A machine and a method for controlled spin flow forming of cans is known from DE 37 83 509 T2. This publication proceeds from a conventional method in which a preformed cup is shaped by ironing, where the bottom of the cup decreases and the length of the cylindrical wall increases. Following that, the wall can be provided in a separate device with a neck section and a flange. For example, die-forming, roller spinning or pressure-forming is proposed for shaping of the neck, using a spinning roller rotating along the outer circumference, with the spinning roller interacting with an inner member provided inside the can body.
DE 37 83 509 T2 proposes a spin flow forming method that controls the metal flow during forming in order to minimize metal damage.
A method for manufacturing a can body is known from DE 69 711 587 T2, where a cup is first made from a plate-like blank by deep-drawing. Following that the cup is shaped by ironing into an ironed workpiece, and then the circumference of the ironed workpiece is calibrated in several individual steps, for which several mold sets are used. Each mold set has a mold and a counter-mold. During this calibration of the circumferential surface of the ironed workpiece, an excess thickness of the cylindrical wall is retained. Finally, a shaped area is created on the wall by so-called hydroforming or a pressure pad, and can project either inwards as a narrowed section or outwards. With this manufacturing method too, various devices are necessary for different process steps, making manufacture very expensive.
Proceeding from this known prior art, it can be regarded as objects of the present invention to provide a device and a method for manufacturing a can body, in particular for aerosol cans, that manage with simple tools and can therefore be used economically even for small quantities.
The present invention provides a device and a method in which a can body (11) with cylindrical wall (12) and a neck section (13) of lower diameter can be manufactured in one working stroke in one working direction (A). The device (10) has a drivable drawing ring (27) used for deep-drawing of a cup from a round, disk-like or plate-like blank (32) in a first phase of the working stroke. After completion of this first phase the cup (70) is drawn with the aid of an ironing mandrel (59) into an ironing channel (38) and formed into an ironed workpiece (73). Finally, a stretch-forming mandrel (58) is moved out of a guide recess (60) of the ironing mandrel (59) and forms the neck section (13) or at least a part thereof in a stretch-drawing phase of the working stroke, in conjunction with a forming depression (48) of a domer (45). With the conclusion of the stretch-drawing phase, the working stroke is completed.
The core of the invention is that the can body used for the manufacture of the can, in particular of an aerosol can, is manufactured as a semi-finished part, generally speaking in a single and preferably vertical working stroke with several mandrels. First, a cup is manufactured from a plate-like and preferably circular blank by deep-drawing with the aid of a drawing ring. After deep-drawing of the cup, the drawing ring preferably acts as a hold-down for an ironing mandrel arranged coaxially to the drawing ring, which mandrel is moved in the direction of the working stroke, engages in the cup and draws the latter through an ironing channel. During this phase of the working stroke, an ironed workpiece with a bottom and a cylindrical wall adjoining the bottom is manufactured from the cup. During ironing, the axial length of the wall increases while the wall thickness decreases. This can be performed by ironing rings inside the ironing channel in several individual steps.
Finally, during the last phase of the working stroke and as a result of stretch-forming of the bottom or of a central bottom section of the ironed workpiece, the axial length of the latter is further increased and a neck section is formed with a diameter smaller than the diameter of the cylindrical wall. To do so, a stretch-forming mandrel is provided which moves relative to the ironing mandrel during the last phase of the working stroke and forms the neck section from the bottom of the ironed workpiece. The stretch-forming mandrel preferably operates here together with a domer which has a forming depression in an extension to the ironing channel. While so doing, the stretch-forming mandrel presses a bottom section of the ironed workpiece into the forming depression of the domer. The ironing mandrel is here preferably used as a hold-down and interacts with a contact face on the domer.
A can body with a cylindrical wall and an adjoining neck section of lower diameter can thus be manufactured by one movement of the drawing ring, of the ironing mandrel and of the stretch-forming mandrel in a preferably vertical direction and in a single working stroke. The can body is manufactured in a single setup. No workpiece is transported between different machining devices between the forming phases. The forming of the plate-like blank into the can body is achieved by one working stroke in one working direction along the longitudinal axis of the device, preferably vertically. The device necessary to do so is of very simple design and hence inexpensive to manufacture. The device can therefore be used economically even for small quantities. Complex tools for manufacturing a narrowed or drawn-in neck section are not necessary. The further processing of the can body into a complete can, in particular into an aerosol can, can then be designed simply and economically: for example, the still closed end of the neck section can be opened by laser cutting or by another cutting process, and the open opposite end closed by inserting a circular bottom. Circular bottoms of this type can be manufactured and connected to the cylindrical wall of the can body simply and inexpensively.
In an advantageous embodiment of the device, the ironing mandrel has a hollow-cylindrical design and coaxially surrounds the stretch-forming mandrel. The ironing mandrel can be mounted movable relative to the stretch-forming mandrel and can contact the outer surface of the stretch-forming mandrel. The stretch-forming mandrel is located, during ironing to manufacture the ironed workpiece, inside the central recess of the hollow-cylindrical ironing mandrel. The stretch-forming mandrel is preferably not moved out of the central recess of the ironing mandrel until the neck section has been shaped from the bottom of the ironed workpiece by stretch-forming.
The drawing ring is moved by a drawing ring drive unit which can, in its movement mode, control or regulate the position or the movement of the drawing ring. In its force mode, the drawing ring drive unit controls or regulates the force exerted by the drawing ring on the cup. In this way, the drawing ring can be used both for deep-drawing of the cup and as a hold-down during ironing.
In a preferred embodiment, a blocking device is provided on the punch which contains the stretch-forming mandrel and the ironing mandrel. The blocking device prevents in its blocking position a relative movement between the stretch-forming mandrel and the ironing mandrel during the working stroke. In particular, the blocking device is in the blocking position during ironing to manufacture the ironed workpiece from the cup. This ensures that the ironing mandrel is in contact by its end area with the bottom of the cup/workpiece, and that no undesirable deformation of the workpiece occurs.
The blocking device is preferably not switched to its release position until the stretch-forming operation for manufacture of the neck section is completed. The ironing mandrel can here preferably be in contact with a contact surface at the end of the ironing channel and perform the function of a hold-down. Thanks to the continued movement of the punch in the working direction, the stretch-forming mandrel is moved out of the central recess of the ironing mandrel and forms the bottom section/bottom of the ironed workpiece. Here it preferably presses the bottom section into a forming depression of the domer. At the end of the stretch-forming operation by the stretch-forming mandrel, the working stroke in the working direction is ended. The punch drive unit moves the punch with the ironing mandrel and the stretch-forming mandrel back against the working direction. During this return stroke movement, the can body can be stripped from the ironing mandrel.
Advantageous embodiments of the present invention are schematically depicted in the drawings in which:
The device 10 is shown in
Coaxially to the drawing ring 26, a hold-down 27, annular in accordance with the example, is mounted movable in the working direction A by a hold-down drive unit 28. Thanks to the through-hole 29 arranged coaxially to the longitudinal axis L and surrounded by the hold-down 27, the drawing ring 26 can be moved by the drawing ring drive unit 25 in the working direction A.
The hold-down 27 is used for clamping of a plate-like blank 32 against a support surface 34 on a table 33 immovably arranged on a frame. The support surface 34 is aligned substantially at right angles to the longitudinal axis L and in the design example runs in a horizontal plane. The longitudinal axis L and the working direction A extend preferably in the vertical direction.
The support surface 34 forms a ring and encloses the opening of a cylindrical deep-drawing channel 37 in the table 33 arranged coaxially to the longitudinal axis L. At the end opposite the support surface 34, the deep-drawing channel 37 is continued by a cylindrical ironing channel 38, where the diameter of the ironing channel 38 is smaller than the diameter of the deep-drawing channel 37. As a result, a step 39 with a ring-shaped retaining surface 40 is formed at the transition point between deep-drawing channel 37 and ironing channel 38. The retaining surface 40 extends in a plane parallel to the support surface 34 and substantially horizontally in accordance with the example.
The ironing channel 38 is closed at its end opposite the step 39 by a domer 45. The domer 45 is pretensioned against the table 33 by an elastic pretensioning means 46, which can for example be formed by a spring array. The domer 45 is thus mounted movable against the force of the pretensioning means 46. In an extension of the ironing channel 38, the domer 45 has on its working side 47 associated with the ironing channel 38 a forming depression 48. The forming depression 48 has at the transition point to the working side 47 the same diameter as the ironing channel 38 and has a first depression area 49 in which the diameter of the forming depression 48 continuously decreases. The wall limiting the forming depression 48 in the first depression area 49 is concave in accordance with the example. Adjoining the first depression area 49, a second depression area 50 is provided coaxially to the longitudinal axis L, representing a cylindrical cavity and ending at a bottom 75.
The deep-drawing channel 37, the ironing channel 38 and the forming depression 48 are arranged along the common longitudinal axis L.
The device 10 has furthermore a punch 56 movable in the working direction A by a punch drive unit 55. The punch 56 contains a carrier part 57 to which a cylindrical stretch-forming mandrel 58 is arranged along the longitudinal axis L. An ironing mandrel 59 is arranged coaxially to the stretch-forming mandrel 58. The ironing mandrel 59 has a hollow-cylindrical form and contacts in the area of its preferably cylindrical guide recess 60 the outer surface of the stretch-forming mandrel 58. The shape of the end area 59a of the ironing mandrel 59 is matched to the shape of the first depression area 49 of the forming depression 48 and, in accordance with the example, is designed rimless and in particular convex. The ironing mandrel 59 is movably mounted along the stretch-forming mandrel 58 and hence along the longitudinal axis L relative to the stretch-forming mandrel 58. It is braced via a force setting means 61 on the carrier part 57 of the punch 56. A spring array 62 with one or more helical springs is used as the force setting means 61 in the design example. The carrier part 57 furthermore has a blocking device 63 which is used to prevent any movement of the ironing mandrel 59 against the working direction A during the working stroke of the punch 56.
In the preferred design example, the blocking device 63 has for that purpose at least one and preferably more slides 64 which can be moved between the carrier part 57 and the ironing mandrel 59 offset to the springs of the spring array 62 or moved out of this intermediate space. The slides 64 are for that purpose arranged radially movable relative to the longitudinal axis L on the carrier part 57, as illustrated schematically by the arrow P in
In an alternative design, the blocking device 63 can have, instead of the movable slides 64, blocking parts swivelable about the longitudinal axis L and swiveled between a blocking position and a release position by a predetermined swivel angle about the longitudinal axis L. In the blocking position, the blocking parts contact the associated end face of the ironing mandrel 59 and prevent its movement against the working direction A and against the spring force of the spring array 62. In the release position, recesses are provided in the ironing mandrel 59 in the extension of the blocking parts, in which recesses the blocking parts can engage such that movement of the ironing mandrel 59 against the working direction A is possible. The blocking parts can be designed matching the slides 64, for example bar-like.
For a better overview, the drive units 25, 28, 55 in
In
As soon as the drawing ring 26 contacts the blank 32, it begins to draw the latter into the deep-drawing channel 37. The hold-down drive unit 28 here regulates the clamping force or the hold-down force of the hold-down 27, so that the blank is drawn from between the hold-down 27 and the support surface 34 and then completely into the deep-drawing channel 37, as illustrated in
Following deep-drawing, a further phase of the working stroke begins in the working direction A. The punch 56 is moved further in the working direction A by the punch drive unit 55. The blocking device 63 is in its blocking position and prevents any movement of the ironing mandrel 59 relative to the stretch-forming mandrel 58. Due to the continued movement of the two mandrels 58, 59 in the working direction A, the ironing mandrel 59 comes into contact with the bottom 71 and draws the cup 70 into the ironing channel 38.
The cup 70 is formed during the joint movement of the ironing mandrel 59 with the stretch-forming mandrel 58 through the ironing channel 38, where the surface area of the bottom 71 decreases while the axial length of the wall section 72 increases and its wall thickness decreases until it finally corresponds to the required dimensions of the wall 12 of the can body 11. At the end of ironing, the cup 70 is shaped into an ironed workpiece 73 as illustrated in
Forming of the cup 70 into an ironed workpiece 73 is followed by a final phase of the working stroke in the working direction A. First, the punch 56 with its two mandrels 58, 59 is moved in the working direction A until the ironed workpiece 73 is in contact with the wall of the first area 49 of the forming depression 48. In this position, the blocking device 63 is switched to its release position. Switching of the blocking device 63 to the release position allows the ironing mandrel 59 to be moved against the working direction A and relative to the stretch-forming mandrel 58. The punch drive unit 55 moves the punch 56 further in the working direction A. Since the domer 45 presses via the pretensioning means 46 against the ironing mandrel 59, the latter is moved against the spring force of the spring array 62 and relative to the stretch-forming mandrel 58. The force setting means 61 formed by the spring array 62 here determines the clamping or holding-down force with which the ironing mandrel 59 presses the ironed workpiece 73 against the wall of the first depression area 49 in the forming depression 48 of the domer 45. At the same time, the stretch-forming mandrel 58 presses a central bottom section 74 of the ironed workpiece 73 into the second depression area 50 of the forming depression 48. The axial length of the ironed workpiece 73 increases here. During this last phase of the working stroke in the working direction A, stretch-forming of the ironed workpiece 73 takes place, with the stretch-forming mandrel 58 and the domer 45 interacting.
After the return stroke of the three forming mandrels 26, 58 and 59 and of the hold-down 27, the next round disk-like or plate-like blank 32 can be inserted and formed as described above in the next working stroke.
The present invention thus relates to a device and a method in which a can body 11 with cylindrical wall 12 and a neck section 13 of lower diameter can be manufactured in one working stroke and in one working direction A. The device 10 has a drivable drawing ring 27 used for deep-drawing of a cup 70 from a plate-like blank 32 in a first phase of the working stroke. After completion of this first phase, the cup 70 is drawn with the aid of an ironing mandrel 59 into an ironing channel 38 and formed into an ironed workpiece 73. Finally, a stretch-forming mandrel 58 is moved out of a guide recess 60 of the ironing mandrel 59 and forms the neck section 13 or at least a part thereof in a stretch-drawing phase of the working stroke, in conjunction with a forming depression 48 of a domer 45. With the conclusion of the stretch-drawing phase, the working stroke is completed.
10 Device
11 Can body
12 Wall
13 Neck section
13
a First area of the neck section
13
b Second area of the neck section
14 Flange
15 Closed free end
16 Wall area
17 Open end
18 Rim
25 Drawing ring drive unit
26 Drawing ring
27 Hold-down
28 Hold-down drive unit
29 Through-hole
32 Blank
33 Table
34 Support surface
37 Deep-drawing channel
38 Ironing channel
39 Step
40 Retaining surface
45 Domer
46 Pretensioning means
47 Working side
48 Forming depression
49 First depression area
50 Second depression area
55 Punch drive unit
56 Punch
57 Carrier part
58 Stretch-forming mandrel
59 Ironing mandrel
59
a End area of the ironing mandrel
60 Guide recess
61 Force setting means
62 Spring array
63 Blocking device
64 Slide
70 Cup
71 Bottom
72 Wall section
73 Ironed workpiece
74 Central bottom section
75 Bottom
A Working direction
L Longitudinal axis
P Arrow
| Number | Date | Country | Kind |
|---|---|---|---|
| 102011002206.6-14 | Apr 2011 | DE | national |
