EP0335301B1 - Method and apparatus for making can bodies - Google Patents

Description

• Entnahme eines Zuschnitts aus einem Magazin,
• mittiges Erfassen des Zuschnitts an seiner Hinterkante und Transportieren des Zuschnitts in eine Formstation,
• kontinuierliches Biegen des Zuschnitts und
• Ausbilden der Nahtverbindung (siehe z.B. US-A-2 864 933),

und eine Vorrichtung mit einem Unterarm, einem äußeren Formwerkzeug, einer Einrichtung zur Führung der Kanten der Dosenzarge vor dem Nahtverbinden, zwei Transporteinrichtungen und einer Nahtverbindungseinrichtung zur Durchführung des Verfahrens (siehe z.B. DE-A- 3 330 171).The invention relates to a method for producing can bodies with a longitudinal seam from individual flat blanks,
consisting of the following steps:

• Removing a blank from a magazine,
• gripping the blank in the center at its rear edge and transporting the blank into a forming station,
• continuous bending of the blank and
• Forming the seam connection (see, for example, US Pat. No. 2,864,933),

and a device with a forearm, an outer molding tool, a device for guiding the edges of the can frame before the seam connection, two transport devices and a seam connection device for carrying out the method (see, for example, DE-A-3 330 171).

For the manufacture of i. There are two ways of generally round can bodies: the manufacture from individual blanks and the manufacture of a corresponding tube from a long strip, from which the can bodies are then separated by separation.

When producing from blanks, these are individually removed from a magazine and sent at high speed through a so-called round apparatus (see, for example, DE-A-33 30 171 or EP-A-0 215 404) in which the plane Is cut into a round preform. At the end of the bending process, the bent blank falls into a so-called catch tray, where it is braked until it comes to a temporary standstill. The rounded blank is then accelerated out of the circular apparatus in its own axial direction, ie by 90 ° to the direction of movement of the flat blank up to the circular apparatus and with i. generally significantly higher speed than the joining speed from the collecting tray into a guide rail surrounded by an outer guide device and further transported to a joining station. A suitable transport device is known from DE-A-33 30 171, which has two transport devices arranged one behind the other, each with two lateral conveyor chains with drivers.

The operating mode between the rounding of the frames and the leading out of the catch shell or the transfer area of the round machine is alternating. A high noise level is associated with this operating mode with constant braking by hard hitting and sudden driving. In addition, the performance is fundamentally limited due to the constant changing of rounding and taking the cut out of the catch tray.

The production of tubes with a welded longitudinal seam, which is then cut into individual can bodies in a separation station, is described, for example, in DE-A-29 47 445. For shaping, the band is drawn through an outer, closed shaping tool which converges in a funnel shape from a further initial opening to an exit opening with a diameter corresponding to the can diameter. Although the continuous forming of a tape offers great advantages in terms of both noise and output in and of itself, it creates problems that lead to By pulling the sheet metal necessary forces to attack the outside of the sheet metal. The tape can also be provided with scoring lines at intervals corresponding to the frame length prior to shaping and seam formation, the separation into individual frames taking place in a so-called separation station (see, for example, US Pat. No. 3,430,410).

Another device for producing curved can bodies from an endless belt is known from GB-A-1 143 161. In a punching station, the endless belt is provided at such intervals with transversely aligned scoring lines which correspond to the height of the bent can bodies. In addition, recesses are punched out in the middle of the band, into which drivers of a centrally arranged driver chain extending through the entire forming station engage. In order to pass through the drivers, the otherwise mandrel of the molding station, which is of cylindrical design, is provided with a corresponding longitudinal groove. An external tool with a coaxial, hollow-cylindrical sliding surface for the endless belt is arranged around the shaping mandrel. The outer tool initially surrounds the mandrel with a small circumferential angle with its inner or sliding surface. Seen in the direction of movement of the endless belt, the outer tool increasingly encloses the mandrel until it completely encloses it except for a recess for the connecting seam of the endless belt and a counter tool for the connecting seam.

The formation of individual blanks in an outer funnel-shaped tool is not only prevented by the fact that the blanks tilt very easily due to the resistance caused by the molding tool and thus make precise guidance impossible. In addition, pulling through the blanks, which are short in relation to the outer mold, also encounters considerable difficulties.

From US-A-3 139 012 a device for the production of curved frames from a flat blank is known. In this device, the individual blanks are not inserted into a fixed funnel tool, but a circumferential, wide elastic band, on which the blanks initially lie flat, is drawn into a hollow guide tool. In order to grasp the rear edges of the blanks, the elastic band has drivers in two lateral rows which bear against the cylindrical outer surface of the shaping mandrel during the driving of the blanks. The elastic band with the carriers attached to it is an expensive wearing part.

The invention is based on the object of specifying a method and a device for producing can bodies with a longitudinal seam from individual, flat blanks, in which or with which the noise development can be reduced and / or the output can be increased.

• daß zunächst nur der mittlere Bereich des Zuschnitts um einen Formdorn in die endgültige Form der Dosenzarge gebogen und gleichzeitig ein zum Erfassen des Zuschnitts durch Transportmittel geeigneter mittiger Kraft bzw. Reibschluß ausgebildet wird, wobei der so weit fertig gebogene Bereich einen Umfangswinkel von 120...190° aufweist und die über den gebogenen Bereich hinausgehenden seitlichen Endbereiche unverformt belassen werden,
• daß der so weit gebogene Zuschnitt in einem weiteren Schritt symmetrisch an beiden Seiten erfaßt wird und die noch unverformten Seitenbereiche des Zuschnitts unter weiterem kontinuierlichen Transportieren und genauem Führen der Kanten des Zuschnitts in die endgültige Form gebogen zu werden.

This object is achieved according to the invention in the method mentioned at the outset by

• that at first only the middle area of the blank is bent around a mandrel into the final shape of the can frame and at the same time a central force or frictional engagement suitable for gripping the blank by means of transport is formed, the so far finished bent area having a circumferential angle of 120 ... Has 190 ° and the lateral end areas extending beyond the curved area are left undeformed,
• that the so far bent blank is grasped symmetrically on both sides in a further step and the still undeformed side areas of the blank are bent into the final shape with further continuous transport and precise guidance of the edges of the blank.

The continuous, predominantly simultaneous transport in one direction and bending of the frame means that there is no noise-related braking and acceleration. Since a blank can only be safely centered in the flat state by lateral guides, the invention provides for a central force or frictional connection to be established between the transport means and the blank at the beginning of the bending, by means of which the pre-centered blank is continued is ensured. The further lateral take-along of the blank is provided - based on the circumference of the frame to be formed - at a point on the blank which is already bent. As a result, there are no relative movements between the blank and the driver pawls. In addition, the finished bent part of the blank can be supported and guided laterally at the same time as it is taken along.

Advantageous developments of the invention are described in the subclaims. Claim 2 thus describes with 180 ° an advantageous circumferential angle for the finished bent central region of the blank before the lateral detection. The measure proposed in claim 3, to capture the blank at its rear edge over a width that is at least 1/10 of the width corresponds to the cut, the guidance of the cut is stabilized in the plane.

The device according to the present invention with a forearm, an outer mold, a device for guiding the edges of the can frame before seam bonding, two successive, rotating transport devices with drivers, the second transport device having two lateral transport means, and a seam connecting device for performing the Process is characterized by
that the forearm is already designed as a shaped mandrel in the region of the initial bending of the blank, the circumference of which corresponds to the clear cross section of the finished can frame and that the shaped mandrel has a central recess on its underside in the longitudinal direction,
that the first transport device is designed as a transport means which is located under the mandrel over a partial length of the same in its longitudinal center plane, that the drivers of the transport means extend into the recess of the mandrel,
that the means of transport has elastic supports extending from below to the mandrel,
that the two inner sides of a first part of the outer mold from a plane that extends over at least one cut length are gradually so far against the longitudinal center plane that they correspond to the lower part of a finished can frame, the outer mold having a central recess for the passage of the has means of transport running in the longitudinal center plane,
that the guide plane from which the outer molding tool emerges is assigned outer guide rails at a distance from the blank width,
that the transport means of the second transport device, in addition to the drivers designed as pawls, have non-elastic supports which extend to the bent part of the can body
and that the first part of the outer mold is followed by a second part of the outer guide tool which further develops the can bodies to the final shape, the outer guide tool having lateral recesses for the passage of the lateral transport means and both transport means having the same mirror image.

A driver pawl of a means of transport can engage in the central recess arranged on the underside of the shaping mandrel, as a result of which the blank is reliably carried along by the shaping tool. When the blank is bent around the mandrel, the central area of the blank is pressed somewhat downwards into the elastic supports of the transport means. This creates a frictional engagement that achieves good lateral stability when guiding the blank through the molding tool. In order to guide the blank into the molding tool in a precisely aligned state, a plane is provided on which the blanks are centered by means of outer guide rails. Since the friction increases during further transport by the molding tool, it is further provided to equip the device with two lateral circumferential transport means which have catches and non-elastic supports with which the already bent area of the blank is laterally guided and supported.

The one central recess of the mandrel on its underside can be assigned further symmetrically arranged recesses, in which parts of the driver pawl can also engage.

The drivers of the transport means arranged in the central longitudinal plane preferably have a width of at least 1/10 of the blank width.

According to claim 6, the lateral transport means are preferably arranged in a plane extending through the axis of the can frame which has been bent so far.

Claim 7 describes an advantageous embodiment of the mandrel. The mandrel consists of individual axially parallel guide rods, the outer lines of which correspond to the clear cross-section of the finished can frame, the central recess of the mandrel in particular being formed by the space between two guide rods which have the same height as the lower layer, and the guide rods being fastened to inner supporting elements indirectly connected to a frame are. Any further lower recesses can then be formed by the space between correspondingly adjacent guide rods.

The upper guide rods of the mandrel can - seen in the direction of transport - start later than the lower guide rods.

In order to be able to adapt the mandrel of the can frame to be produced precisely, it is proposed according to claim 9 to design the lower and upper guide rods to be adjustable in height relative to one another.

According to claim 10, the outer molding tool advantageously also consists, at least in its first part, of guide rods which extend over at least a cut length are arranged in one plane and then gradually upwards so far against the longitudinal center plane that the imaginary curve line enclosed by their inner lines corresponds to the lower part of the finished can frame, the guide rods being fastened to supporting elements connected to the frame.

The second part of the outer mold, which further develops the can bodies to the final shape, can consist of guide rods and / or rollers. In order to adapt to specific circumstances, the guide rods and the rollers of the outer mold are each assigned to a right and left upper and a lower roller guide tool, which can each be individually adjusted. For better grasping of the can bodies, the rollers of the outer molding tool preferably have a concave contour which is matched to the outer contour of the curved frame.

In order to arrange the broadest possible elastic supports, it is provided that the transport means arranged under the mandrel in its longitudinal center plane is designed as a double roller chain.

The height of the transport device can be adjusted by means of lifting elements in order to adjust the transport device arranged under the forming mandrel in its longitudinal center plane to different can diameters and to adjust the distance between the chain supports and the forming mandrel. In a preferred embodiment, the lateral transport means are designed as single roller chains and are radial in height by means of lifting means and by sliding elements adjustable. In order to align the height of the cut edges exactly, a lower and upper skid is arranged at the outlet end of the grooved rail.

Fig. 1

die Transport- und Führungseinrichtung in einer Seitenansicht,

Fig. 2

die Transport- und Führungseinrichtung in der Draufsicht und die

Fig. 3 bis 7

die Transport- und Führungseinrichtung jeweils in einem Schnitt gemäß den Linien III-III bis VII-VII in Fig. 1.

An embodiment of the object of the invention is shown in the drawing and is explained in more detail below. Show it:

Fig. 1

the transport and guide device in a side view,

Fig. 2

the transport and guide device in plan view and the

3 to 7

the transport and guide device in each case in a section along the lines III-III to VII-VII in Fig. 1st

The device for transporting and guiding can blanks Z and for forming them into can bodies extends over a forming section F and over a guiding section in front and behind. The molding section has a first and second transport device 1 and 2, a shaping mandrel 6, rod-shaped and roll-shaped outer shaping and guiding tools 24, 25, 31 to 33 and 42 to 44 and a grooved rail 38. The first transport device 1 takes over the advance of the can blanks (hereinafter also only briefly: blanks) Z from a magazine stacker known per se (not shown here) and transfers it to the second approximately in the middle of the molding section F. Transport device 2.

The first transport device 1 essentially consists of a double roller chain 3 running in the central longitudinal plane M of the molds with driver pawls 4 and elastic chain supports 5 arranged between the driver pawls. To adjust this transport device 1 to different can diameters D and to adjust the distance between the chain supports 5 and the (Dependent on the can diameter) mandrel 6, the transport device 1 is adjustable in height by means of lifting elements 7.

The second transport device 2 consists of mirror-image same feed chain drives 8 and 9, which are arranged laterally opposite one another from the forming mandrel 6 in one plane. On the single roller chains 10 of the feed chain drives 8, 9, drivers 11 and non-elastic supports 12 are fastened, which serve to feed or to support and guide the blanks Z which are already fully formed in the lower or middle region. The chains 10 and their drivers 11 are adjustable to compensate for division errors and other manufacturing tolerances on mutual alignment. The feed chain drives 8, 9 can be adjusted radially or horizontally for adaptation to the respective can diameter D by means of lifting elements 13 and by means of sliding elements 49.

The shaping mandrel 6 consists of a multiplicity of round bars 14, 15 which are attached to the lower and upper support elements 16, 17 in a circular manner, ie forming an (imaginary) radius. The round bars 14, 15 have different lengths. The lowest round bars 15 are the longest and are already present at the beginning of the molding section F. As the blanks Z are progressively formed, the other round bars 14 and 15 - seen in the feed direction - are added. The uppermost round rods 15 are the shortest and begin shortly before the second transport device 2. The lower half of the forming mandrel 6, consisting of the round rods 15 fastened to the supporting elements 17, is opposite the upper half, consisting of the rods 14 fastened to the supporting elements 16 The height of the mandrel 6 can be changed to a small extent and can thus be set precisely to a predeterminable can diameter D.

The support elements 16, 17 are fastened in a forearm profile 18 with an integrated cable and hose channel 19. The forearm profile 18 is screwed onto the frame 21 via an intermediate piece 20.

3 shows a section at the beginning of the molding section F. The blank Z lies on bars 24, 25 of a right or left guide cage fastened to support elements 22, 23 and on the elastic chain supports 5 of the first transport device 1. The rods 24, 25 are still arranged horizontally. The support elements 22, 23 are connected via right and left supports 22 ', 23' and fastened to the frame 21 via these.

The centering and alignment of the blank Z is carried out by lateral guides 26, 27, which can be set in the distance and in their direction sensitively. For the advance, the blank Z is gripped by a pawl 4. To stabilize the feed, the pawl 4 (as 3 and 4) formed with three projections so that the blank Z is detected over a certain width. The projections of the pawl 4 partially engage between the

Bars 15 of the mandrel 6. At the beginning of the molding section F, only the two lower bars 15 of the mandrel 6 come into contact with the blank Z.

Fig. 4 shows a section approximately in the middle of the guide baskets 22/24 and 23/25. While the side parts of the blank Z still extend undeformed, the blank Z is already bent in its central region and becomes firm between the two lower bars 15 of the shaping mandrel 6 and the elastic chain supports provided with a well-adhering surface due to the resulting deformation 5 pinched. The two as yet undeformed side parts of the blank Z connect tangentially to the central circular region of the blank Z with the radius R = D / 2.

The two lateral guide baskets 22/24 and 23/25 essentially end with the first transport device 1. At its end (cf. FIG. 5), the blank Z is finished bent in its central region over a circumference of approximately 180 °. The blank now lies against the complete lower half of the mandrel 6 consisting of the rods 15. The two undeformed side parts of the blank Z, which still correspond to a circumferential length of about 90 ° or (π / 4) D, are tangentially connected to the central circular area of the blank with the radius D / 2. At this point, the feed of the blank Z from the second transport device 2 with the two Feed chain drives 8, 9 are taken over, their rigid supports 12 taking over the lateral guidance of the blank Z in a horizontal orientation instead of one of the guide rods.

6 shows, in a section which is further away in the feed direction, along the line VI-VI in FIG. 1, a lower rod guide tool with guide rods 31 fastened to support elements 28 and two lateral upper rod guide tools with guide rods 32 or fastened to support elements 29, 30. 33 of a second part of the outer mold. The guide rods 31 of the lower rod guide tool run parallel to the mandrel 6 and are set radially so that the blank Z bears against the rods 15 of the lower part of the mandrel 6. The guide rods 31 - seen in the circumferential direction - are arranged offset to the rods 15 of the mandrel 6. The rods 32, 33 of the upper lateral rod guide tools are converged in such a way that the end regions of the blank Z are bent with the rods 14 during further advance into the upper region of the mandrel 6. The edges 34, 35 of the side parts of the blank Z dip into oppositely arranged grooves 36, 37 of a groove rail 38 which is arranged between the forearm profile 18 and the intermediate piece 20. The distance between the two grooves 36, 37 decreases continuously in the feed direction until the blank Z is completely bent around the shaping mandrel 6 and has assumed a closed circular cross section with the diameter D. The completely curved blank Z is outside of roller guide tools 39, 40, 41, the rigid supports 12 of the chains 10 of the feed chain drives 8, 9 and the guide grooves 36, 37 of the groove rail 38 fully enclosed (cf. the section shown in FIG. 7 just before the welding point S).

The rollers 42 ... 44 of the roller guide tools 39 ... 41 are designed as so-called diabolo rollers and are precisely adapted to the circular cross section of the curved blank Z, which is also referred to as the frame. The rollers 42 ... 44 are individually adjustable in the radial direction, so that the edges 34, 35 of the rounded blank Z abut against one another with pressure 45. At the end of the grooved rail 38, a height-adjustable skid 46 or 47 is arranged below and above the grooved plane in order to align the cutting edges 34, 35 exactly in height.

Viewed downstream of the delivery flow, the welding point S is located immediately behind the skids 46, 47, the welding being able to be carried out, for example, by a focused laser beam 48.

Claims (19)

1. A process for the manufacture of can bodies with side seam from individual flat cut blanks (Z), comprising the following steps:

   - removal of a cut blank (Z) from a magazine,

   - gripping of the cut blank (Z) at the centre of its rear edge and transportation of the cut blank (Z) to a shaping station,

   - continuous bending of the cut blank (Z) and

   - forming of the seam,

   characterized in that

   - initially only the central area of the cut blank (Z) is bent around an inner shaping mandrel (6) into the final shape of the can body and at the same time a central non-positive or frictional connection is formed which is suitable for the gripping of the cut blank (Z) by transporting devices (3), the area finish-bent to this extent having an inscribed angle of 120...190° and the side end areas extending beyond the bent area remaining unshaped,

   - in a further step the cut blank (Z) bent to this extent is gripped symmetrically at both sides and the still unshaped side areas of the cut blank (Z) are bent into the final shape with further continual transportation and precise guidance of the cut blank's (Z) edges.
2. A process according to claim 1, characterized in that the inscribed angle of the finish-bent central area is 180°.
3. A process according to claim 1 or 2, characterized in that the cut blank (Z) is gripped at its rear edge over a width corresponding to at least 1/10 of the width of the cut blank (Z).
4. A device with a lower arm member (18), an outer shaping tool (24,25), a facility for guiding the edges of the can body prior to seam joining, two rotating transporting devices arranged in series (1,2) with pawls (4,11), the second transporting device (2) featuring two lateral transporting means (8,9), and a seam-joining facility for carrying out the process according to claims 1 to 3,
   characterized in that

   - already in the area of the initial bending of the cut blank (Z), the lower arm member (18) is configured as an inner shaping mandrel (6), the circumference of which corresponds to the inside cross-section of the finished can body, and that the inner shaping mandrel (6) exhibits a central recess on its underside in longitudinal direction,

   - the first transporting device (1) is configured as a transporting means (3) located under the inner shaping mandrel (6) over a partial length of the same in its longitudinal centre plane (M),

   - the pawls (4) of the transporting means (3) extend into the recess of the inner shaping mandrel (6),

   - the transporting means (3) features elastic chain supports (5) extending from the bottom up to the inner shaping mandrel (6),

   - the two inner sides of a first part of the outer shaping tool (24,25) are gradually guided upwards from a plane extending over at least one cut blank length so far towards the longitudinal centre plane (M) that they correspond to the lower part of a finished can body, the outer shaping tool (24,25) featuring a central recess for the passage of the transporting means (3) travelling in the longitudinal centre plane

   - outer guide rails (26,27) with a spacing corresponding to the width of the cut blank are assigned to the guidance plane from which the outer shaping tool (24,25) emerges,

   - in addition to the dogs configured as pawls (11), the transporting means (8,9) of the second transporting device (2) feature non-elastic supports (12) extending to the finish-bent part of the can body,

   - the first part of the outer shaping tool (24,25) is followed by a second part of the outer guide tool (31...33; 42...44) which further forms the can bodies up to their final shape, the outer guide tool (31-33; 42-44) featuring lateral recesses for the passage of the lateral transporting means (8,9), the two transporting means (8,9) being of identical configuration mirror-image-wise.
5. A device according to claim 4, characterized in that the pawls (4) of the transporting means (3) arranged in the longitudinal centre plane (M) exhibit a width of at least 1/10 of the cut blank width (Z).
6. A device according to claim 4 or 5, characterized in that the lateral transporting means (8,9) are arranged in a plane running through the axis of the can body finish-bent to this extent.
7. A device according to any of claims 4 to 6, characterized in that the inner shaping mandrel (6) consists of individual axially parallel guide rods (14,15) whose outer generatrices correspond to the inside cross-section of the finished can body and that the central recess of the inner shaping mandrel (6) is formed by the space between two lower guide rods (15) disposed at the same level and that the guide rods (14,15) are fixed to inner supporting elements (16,17) connected indirectly to a frame (21).
8. A device according to claim 7, characterized in that the upper guide rods (14) of the inner shaping mandrel (6) - viewed in the direction of transportation - commence later than the lower guide rods (15).
9. A device according to claim 7 or 8, characterized in that the upper and lower supporting elements (16,17) which support the guide rods (14,15) are height-adjustable relative to each other.
10. A device according to any of claims 4 to 9, characterized in that the first part of the outer shaping tool is formed from guide rods (24,25) which are arranged in one plane over at least one cut blank length and thereafter are gradually guided upwards so far towards the longitudinal centre plane (M) that the imaginary curve formed by their inner generatrices corresponds to the lower part of the finished can body, the guide rods (24,25) being fixed to support elements (22,23) connected to the frame (21).
11. A device according to any of claims 4 to 10, characterized in that the second part of the outer shaping tool, which further forms the can bodies up to their final shape, consists of guide rods (31 ... 33) and/or rollers (42...44).
12. A device according to claim 11, characterized in that the guide rods (31...33) of the outer shaping tool are assigned to a right-hand and a left-hand upper and a lower supporting element (28...30) which are each individually adjustable.
13. A device according to claim 11, characterized in that the rollers (42...44) of the outer shaping tool are assigned to a right-hand and a left-hand upper and a lower roller guide tool (39...41) which are each individually adjustable.
14. A device according to claim 11, characterized in that the rollers (42...44) of the outer shaping tool exhibit a concave contour adapted to the outer contour of the bent can body.
15. A device according to any of claims 4 to 14, characterized in that the transporting means arranged under the inner shaping mandrel (6) and in its longitudinal centre plane (M) is configured as a double roller chain (3).
16. A device according to any of claims 4 to 15, characterized in that the transporting means (3) arranged under the inner shaping mandrel (6) and in its longitudinal centre plane (M) is height-adjustable using lifting elements (7).
17. A device according to any of claims 4 to 16, characterized in that the lateral transporting means (8,9) are configured as single roller chains (10).
18. A device according to any of claims 4 to 17, characterized in that the lateral transporting means (8,9) are height-adjustable using lifting elements (13) and radially adjustable using slide elements (49).
19. A device according to any of claims 4 to 18, characterized in that a lower and an upper slide skid (46,47) are arranged at the exit-side end of the grooved rail.

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