GB2323316A

GB2323316A - Container end forming apparatus

Info

Publication number: GB2323316A
Application number: GB9805849A
Authority: GB
Inventors: Reginald Thomas Hill
Original assignee: AIDPAC INT Ltd
Current assignee: AIDPAC INT Ltd
Priority date: 1997-03-21
Filing date: 1998-03-20
Publication date: 1998-09-23
Also published as: GB9705936D0; AU6738898A; WO1998042459A1; GB9805849D0

Abstract

A seaming head of a container seaming machine comprises inner (22) and outer (24) portions of an eccentric mechanism, one or more roller tools (16) being carried by the outer portion (24). The portions are driven independently by master and slave servo motors (72,74), the eccentric mechanism enabling the two portions to be rotated in unison about a machine axis (12) but also to be rotated relative to one another about an off-set axis (26) whereby to vary the distance of the roller tool from the machine axis. A composite balancing mass (40) comprises primary (42) and secondary (46) discs which are rotatable in unison about the machine axis and also relatively rotatable to shift mass radially in order to balance radial movements of the roller tools.

Description

CONTAINER END FORMING APPARATUS End pieces for cans (hereinafter referred to as "can ends") are ordinarily secured to cylindrical can bodies by folding a rim of the end about an out-turned end flange of the cylindrical can body. The folding of the rim is effected progressively around the can, and may be effected in two or more stages using different forms of tool. Such operations are usually referred to as seaming, and the tools referred to as seaming tools.

Can seaming is most commonly effected by clamping the can body and end axially together by means of a can-lifting base table and endsupporting seaming chuck, and then rotating the clamped can body and end whilst roller-type seaming tools are brought in radially, in turn, to effect multi-stage seaming. Alternatively, the tools can be revolved about a stationary can body and end. Most usually, such roller tools are driven solely by their frictional engagement with the can. To overcome slippage between the tools and the can, attempts have in the past been made to drive the tools at synchronous speed with the can by means of a frictional drive between the seaming chuck and the tools, but such have been rarely used.

Other seaming methods used or proposed have included the use of fixed seaming rails against which the can (and end) is rolled, and the use of annular seaming tools, which encircle the can for progressive engagement of the tool about the can.

It is one of the objects of the present invention to provide improved roller-type seaming apparatus.

The invention provides, in one of its aspects, container end forming apparatus comprising: (i) supporting means adapted to retain a container body in a pre determined disposition relative to a machine axis; (ii) a roller-type forming tool presenting a forming profile at an outer periphery of the tool; (iii) positioning means bearing the tool at a distance from the machine axis and being adjustable to vary said distance; and (iv) driving means operable (a) to cause rotation of the tool-positioning means about the machine axis whereby to cause the tool to orbit a container retained by said supporting means, and (b) to adjust the positioning means during rotation whereby to move the tool into and out of operative engagement with the container in effecting a seaming operation on the container, an inner limit of movement of the tool by the driving means being variable during rotation of the positioning means.

In a preferred construction, the positioning means comprises inner and outer portions of an eccentric mechanism which enables the portions to be rotated in unison about the machine axis by the driving means and also permits the portions to be rotated relative to one another about an axis of the inner portion which is displaced radially from the machine axis, whereby to vary the distance of the seaming tool (born by the outer portion) from the machine axis. The limit of relative rotation of the portions in at least one direction (moving the tool inwards) is variable by the adjusting means during running.

The inner portion of the eccentric mechanism may comprise a circular body (e.g. a disc), the axis of which defines said off-set axis, the outer portion comprising a body (which may again be a circular disc) which has a centrally off-set aperture to accommodate the inner body, the outer body being rotatably located on the inner body.

The outer body may be coupled to a composite balancing mass which comprises a primary body in which there is an off-set circular aperture which accommodates a secondary body, the primary body being rotatably located on the secondary body. The secondary body may be keyed to the inner portion of the eccentric mechanism for rotation therewith about the machine axis, the axis of the secondary body being radially off-set from the machine axis, and the primary body of the balancing mass and the outer portion of the eccentric mechanism being coupled for rotation together.

The driving means preferably comprises a pair of servo motors arranged to drive, respectively, the inner and outer portions of the eccentric mechanism. Control of the servo motors may be by means of a two-axis motion controller.

There now follows a description, to be read with reference to the accompanying drawings, of can seaming apparatus which illustrates the invention by way of example.

In the accompanying drawings Figure 1 is an axial cross-section through a seaming head of a seaming machine; and Figure 2 is a schematic diagram illustrating operating means for control of the seaming head in use.

A seaming head (Figure 1) of a container seaming machine, which seams metal ends on to metal or non-metal containers, comprises a fixed cylindrical pillar 10 defining a vertical machine axis 12. Can-supporting means comprises a lifting table (not shown, but of a generally conventional kind) arranged beneath the pillar to lift a can body and present it to a chuck 14 secured to the bottom end of the pillar. The table is thus adapted to clamp a can body and an end axially together against an underside of the chuck 14, the can body so being retained in a predetermined disposition relative to the machine axis 12. [In an alternative embodiment according to the invention, the chuck 14 can be arranged to drop to clamp the can body and end against a stationary table beneath.] The seaming head comprises positioning means bearing a plurality of (i.e. two or more) roller-type seaming tools 16. Each tool forms an external seaming profile 18, presenting an outer peripheral surface of the tool, and is freely rotatable about a central axis of rotation 20. The tools are carried by the positioning means with their axes of rotation 20 at a variable distance radially from the machine axis 12.

The positioning means comprises inner 22 and outer 24 portions of an eccentric mechanism which enables the portions to be rotated in unison about the machine axis 12 and also permits the portions to be rotated relative to one another about an off-set axis 26 which is displaced radially from the machine axis 12, whereby to vary the distance of the seaming tools 16 from the machine axis.

The inner portion 22 of the eccentric mechanism comprises an upper part 28 which forms an inner cylindrical driving sleeve which surrounds the pillar 10. The sleeve is rotatable about the pillar, the interior of the sleeve being spaced from the pillar and there being a bearing 30 positioned between the pillar and the sleeve at its bottom end.

A lower part 32 of the inner portion 22 is in the form of a thick circular disc, the axis of the disc defining the off-set axis 26.

The outer portion 24 of the eccentric mechanism also comprises a thick circular disc 34, the outer disc 34 having an off-set circular aperture 36 through it which accommodates the inner disc 32 and a bearing 38 which locates the outer disc rotatably on the inner disc.

The outer disc 34 is coupled to a composite balancing mass 40 of the positioning means. The balancing mass comprises a primary circular disc 42 through which there is an off-set circular aperture 44 to accommodate a secondary (inner) circular disc 46 and a bearing 48 which locates the primary disc rotatably on the secondary disc. The secondary disc 46 is keyed to the upper portion 28 of the inner portion 22 of the eccentric mechanism for rotation with it, the axis of the disc being radially off-set from the machine axis 12 defined by the pillar 10. A first drive peg 50 in the primary disc is engaged in a radially extending slot 52 in the outer disc 34 of the eccentric mechanism, whereby the two discs are coupled for rotation together.

The balancing mass 40 is positioned above the inner and outer discs 32,34 of the eccentric mechanism. A second drive peg 54 projects upwardly from the primary balancing disc 42 for engagement in an outer driving sleeve 56 which is rotatably mounted by means of bearings 58,60 on the driving sleeve 28 of the inner portion 22 of the eccentric mechanism. The sleeve 56 is supported externally by a further pair of bearings 62,64 for rotation within a fixed housing 66.

A first driving gear 68 (or pulley) is keyed on to an upper end portion of the outer driving sleeve 56, whereby the outer sleeve can be driven to rotate about the machine axis 12.

A second driving gear 70 (or pulley) is keyed on to an upper end portion of the inner driving sleeve 28, whereby the inner sleeve can be driven to rotate about the machine axis 12.

With reference to Figure 2, master and slave servo motors 72,74, of driving means of the apparatus, are arranged in a conventional manner (for such drives) to drive the first and second driving gears 68,70 respectively. The motors are individually controlled through digital servo amplifiers 76,78 from a two-axis motion controller 80. A membrane keypad 82 enables control instructions to be given to the controller 80.

Upon driving the two driving gears 68,70 at the same rotational speed, the whole assembly of the positioning means becomes rotated about the machine axis 12, the seaming tools 16 so being caused to orbit a can body and end clamped against the chuck 14. However, by introducing a difference in driving speed between the two gears a relative rotation between the inner and outer elements of the positioning means can be effected.

Upon so rotating the outer portion 24 of the eccentric mechanism relative to the inner portion 22, the outer disc 34 bearing the tools 16 becomes rotated about the off-set axis 26 defined by the inner disc 32, so varying the radial distances of the tools from the machine axis 12. In this manner the positioning of the tools relative to the can body and end can be varied whilst the tools continue to orbit the machine axis during the seaming operations. Furthermore, the inner and outer limits of movement of the tools are determined by the operation of the motion controller 80, these limits being variable at all times during running, enabling adjustments to be made readily and under close control without having to stop the machine and disassemble mechanical components.

Claims

1. Container end forming apparatus comprising: (i) supporting means (10,14) adapted to retain a container body in a pre-determined disposition relative to a machine axis (12); (ii) a roller-type forming tool (16) presenting a forming profile (18) at an outer periphery of the tool; (iii) positioning means (22,24) bearing the tool at a distance from the machine axis and being adjustable to vary said distance; and (iv) driving means (68,72;70,74) operable (a) to cause rotation of the tool-positioning means about the machine axis whereby to cause the tool to orbit a container retained by said supporting means, and (b) to adjust the positioning means during rotation whereby to move the tool into and out of operative engagement with the container in effecting a seaming operation on the container, an inner limit of movement of the tool by the driving means being -variable during rotation of the positioning means.

2. Apparatus according to claim 1 in which the positioning means comprises inner (22) and outer (24) portions of an eccentric mechanism which enables the portions to be rotated in unison about the machine axis by the driving means and also permits the portions to be rotated relative to one another about an axis of the inner portion which is displaced radially from the machine axis, whereby to vary the distance of the forming tool from the machine axis.

3. Apparatus according to claim 2 in which the inner portion of the eccentric mechanism comprises a circular body (32) the axis of which defines said off-set axis (26).

4. Apparatus according to claim 3 in which the outer portion of the eccentric mechanism comprises a body (34) having a centrally off-set aperture (36) which accommodates the inner body (32), the outer body being rotatably located on the inner body.

5. Apparatus according to claim 4 in which the outer body (34) is coupled to a composite balancing mass (40) of the positioning means.

6. Apparatus according to claim 5 in which the balancing mass comprises a primary body (42) in which there is an off-set circular aperture (44) which accommodates a secondary body (46), the primary body being rotatably located on the secondary body.

7. Apparatus according to claim 6 in which the secondary body (46) is keyed to the inner portion (22) of the eccentric mechanism for rotation therewith about the machine axis (12), the axis of the secondary body being radially off-set from the machine axis.

8. Apparatus according to claim 7 in which the primary body (42) of the balancing mass and the outer body (34) of the eccentric mechanism are coupled for rotation together.

9. Apparatus according to any one of claims 1 to 8 in which the driving means comprises master and slave servo motors (72,74).

10. Container end forming apparatus substantially as hereinbefore described with reference to the accompanying drawings.