Capping apparatus

Abstract: A capping apparatus, in particular for applying PRESON™ style caps to glass jars, comprising a chute (15) with grooved sidewalls to allow free passage of the caps irrespective of tab orientation. At the chute outlet (20), stops (35) depend from a bridge bar (30) in order to engage the leading cap (60) above its tab (62), again allowing caps to be presented in random orientation.

Description: This invention relates to a capping apparatus and a method of applying caps, particularly but not exclusively "press-on" type caps, to containers such as glass jars. Generally, such capping apparatus is to be fitted above and at an angle to a horizontal conveyor, along which containers pass during the capping process. Press-on caps, hereinafter referred to as PRESON™ caps, typically comprise a metallic disc, or panel, from which depends a polymer skirt. Around the inner circumference of the skirt are one or more ridges which snap fit over the neck of a container. An outwardly projecting tab at the base of the skirt enables the cap to be pried off the container. A sealing compound between the panel and the skirt ensures a hermetic seal is formed by the cap when it has been applied to the container. Capping apparatus, or cappers, are known for press-on, twist-off caps, in which caps pass down a chute to a cap pick-up point at which they are collected one-by-one by containers passing beneath the end of the chute. At the cap pick-up point, the leading cap is engaged by stops just ahead of its transverse diameter which prevent the cap from falling out of the chute (see WO-A-94/18108). The tab of the PRESON™ cap has always been a problem when applying the caps to jars. The asymmetric nature of the cap means that the caps must be oriented so that the tab does not foul on the apparatus or on neighbouring caps either in the capper chute or during application. If the caps are not pre-oriented, then the caps may not slide freely in the chute, so that a cap is not in position for collection by the next jar/bottle. Furthermore, pre-orientation is required to ensure that the tab does not become caught on the stops at the mouth of the chute which might prevent release and also result in bottles being missed in the capping process. Conversely, if the stops are designed to accommodate the tab when in a position where the tab is presented parallel to the chute side walls, the cap may fail to be engaged by the stops and may fall out of the chute onto the bottle conveyor, requiring halting of the capping process in order to clear the conveyor. Since capping processes are high speed operations, such a situation is clearly unacceptable. According to the present invention, there is provided a machine for applying a cap to a container, the cap having a panel and a skirt depending from the panel, the machine comprising: a chute for feeding a series of caps to a series of containers, the chute having an outlet; one or more stops for preventing the leading cap from falling out of the chute outlet; and means for biasing the leading cap downwardly towards the container; characterised in that the chute includes a tongue and wings for supporting the rear and front respectively of the leading cap; the stop or stops extend downwardly from the biasing means to a point above the position where a hem projects from the base of the cap skirt; and in that, in operation when a container impinges on the leading cap, the cap is pulled off the tongue and pivots towards the horizontal about the rear edge of the wings of the chute outlet, thereby causing the biasing means and stops to pivot away from the cap and release the cap from the chute. Preferred embodiments of the machine according to the invention are defined in claims 2-4. According to a further aspect of the present invention, there is provided a method of applying a cap to a container. The method is defined in claim 5. A preferred embodiment of the invention will now be described, by way of example only, with reference to the drawings, in which: Figure 1 is a side section of the chute outlet of a capping apparatus; Figure 2 is a section through II-II on figure 1; Figure 3 is a side view of the bridge bar, showing a cap in position; Figure 4 is a plan view of the bridge bar, showing a cap in position; Figure 5 is a front view of the bridge bar, again showing the cap in position for collection; and Figure 6 is a plan view of the chute outlet. Figure 1 shows the front portion of a capping apparatus 10 according to the invention. The capper 10 comprises a chute 15 along which caps pass to a pick-up point at the chute outlet 20. At the chute outlet, the cap is supported by a tongue 22 which extends from the base of the chute and by inwardly facing wings 54 on front and rear rail clips 50, 52 which will be described with reference to figure 6 below. The leading cap is held down on the chute by a "hold down" 25 and is prevented from falling out of the chute by stops 35 on bridge bar 30. The bridge bar is biased downwards by means of spring 38 and is pivotable about its rear end (see figure 3). A slide block 40 extends beyond the chute outlet 20 and is used to guide the cap to the correct position for alignment with the bottle neck. In figure 2, a cap 60 is shown in position on the chute. The cap 60 is of the PRESON™ type and has a metal central panel 66 and a polymer skirt 64 and tab 62. The chute 15 comprises side walls 16 and a base 18. The tab 62 of the cap extends sideways from the cap skirt 64, into a groove 17 in one of the side walls. Both side walls have grooves 17, so that the orientation of the cap is not important within the chute. It can be seen that the transverse cross-section shape of the side walls is L-shaped. The top of the side walls is thus narrower than the base so that undue lateral movement of the cap is prevented by engagement of the cap skirt 64 by the upper side walls. Bridge bar 30 is shown in different views in figures 3 to 5, with cap 60 shown in retained position in each figure. As is noted above, stops 35 on the bridge bar extend approximately perpendicularly to the base of the chute in order to retain the cap just ahead of its diameter. Although in figure 4, the tab 62 is not adjacent to either of the stops 35 so that the stops of a known capper would not require modification in this instance, it is apparent in figure 5 that the stops 35 of the present invention are above the tab position so that the tab will readily sit beneath the stops if oriented across the chute. The bridge bar 30 is pivotable about fulcrum 42 for biasing purposes as described below, with spring 38 acting on secondary bar 32. In use, caps are steam heated to soften the polymeric material of the cap skirt and are fed panel uppermost down the chute 15, with their tabs 62 randomly oriented, until engaged by the stops 35 on the bridge bar 30 at the chute outlet 20, with the rear of the cap resting on tongue 22 of the chute base. Unlike prior art cappers, the stops are provided solely above the cap. No stops are required on front and rear rail clips 50, 52 at the chute outlet but wings 54 are still provided to support the front of the leading cap as shown in figure 6. Hold down 25 guides the caps towards the chute outlet and prevents twisting of the caps out of the chute. Containers such as glass bottles or jars pass along a horizontal conveyor under the capper. The leading edge of a jar impinges on a cap held at the chute outlet 20, pulling the cap forward as the jar is moved along its horizontal conveyor. The steam softened skirt of the cap deforms as the cap is pulled forward against the action of the rigid stops. Since the tongue 22 and wings 54 are spaced from each other, this forward action of the jar will also cause the cap to be drawn off the tongue of the chute and tilt towards the horizontal, pivoting about the rear edge of wings 54. The dropping of the cap off the tongue is believed to be the biggest influence in release of the cap from the chute. As the cap drops down away from the stops and the plastic skirt deforms, the forward motion of the cap eventually overcomes the downward force of the bridge bar and the restraining interference force of the stops. The stops then move up the crown radius of the cap in a camming action as the bridge bar pivots about fulcrum 42. This camming action further assists release of the cap. Once the cap exits the chute, the bridge bar 30 acts on the rear half of the cap as the spring 38 forces the bar to pivot back to its "at rest" position to assist in ensuring that the cap sits correctly on the jar. The slide block 40 may include magnets which attract the front of the cap upwards so as to cooperate with the bridge bar in achieving this correct positioning. Once the bar is in its "at rest" position, the stops are correctly positioned to halt the following cap. It has been found that the capping process using the apparatus of the present application can achieve capping speeds of just over 600 caps/min and capping speeds of 800 caps/minute are considered possible.

Claims: A machine (10) for applying a cap (60) to a container, the cap having a panel (66) and a skirt (64) depending from the panel, the machine comprising: a chute (15) for feeding a series of caps to a series of containers, the chute having an outlet (20); one or more stops (35) for preventing the leading cap from falling out of the chute outlet (20); and means for biasing (30) the leading cap downwardly towards the container; characterised in that the chute includes a tongue (22) and wings (54) for supporting the rear and front respectively of the leading cap; the stop or stops (35) extend downwardly from the biasing means to a point above the position where a hem projects from the base of the cap skirt; and in that, in operation when a container impinges on the leading cap, the cap is pulled off the tongue and pivots towards the horizontal about the rear edge of the wings of the chute outlet, thereby causing the biasing means and stops to pivot away from the cap and release the cap from the chute. A machine according to claim 1, in which the cap includes an outwardly projecting tab (62) at the base of the skirt, and in which the stop or stops extend downwardly to a point above the position where the tab projects from the cap skirt. A machine according to claim 1 or claim 2, in which the chute includes grooves (17) at the base of each side wall (16). A machine according to any one of claims 1 to 3, in which the biasing means comprises a bridge bar (30) and two stops (35) are positioned either side of the centre of the bar, the distance between the stops being slightly less than the widest dimension of the cap skirt, above the hem or tab. A method of applying a cap (60) to a container, the cap having a panel (66), a skirt (64) depending from the panel and an outwardly projecting tab (62) at the base of the skirt, the method comprising the steps of: passing a cap along a chute (15) to a chute outlet (20); retaining the cap at the chute outlet by engaging, with downwardly extending stops (35), the skirt of the cap above the tab, supporting the rear of the cap on a tongue (22) and the front of the cap on wings (54), prior to pick-up of the cap by the container; releasing the cap from the chute outlet (20) by pulling the cap off the tongue (22) and pivoting the cap towards the horizontal about the rear edge of the wings (54) when the container engages the front edge of the cap. A method according to claim 5, in which the releasing step further comprises: drawing the cap beneath the stops; and biasing the trailing edge of the cap towards the container.

Inventors: DARLEY JOHN, GIBBS ROY THOMAS, VAN DEN AKKER RICHARD HENRY, DARLEY, JOHN, GIBBS, ROY THOMAS, VAN DEN AKKER, RICHARD HENRY
Applicants: CARNAUDMETALBOX SA, METAL BOX PLC
Application year: 1996
Main classification: B67B3
IPC codes: B67B3