WO1994017319A1

WO1994017319A1 - Eccentric displacer for gears

Info

Publication number: WO1994017319A1
Application number: PCT/GB1994/000179
Authority: WO
Inventors: Thomas Tulloch; Thomas Donaldson; James Carmichael
Original assignee: Khs Carmichael Limited
Priority date: 1993-01-30
Filing date: 1994-01-28
Publication date: 1994-08-04
Also published as: GB9301906D0; AU5890294A

Abstract

A means for varying the distance between gear supporting shafts (3) is provided by mounting at least one of the shafts (3) eccentrically on a rotatable plate (2) which, when rotated, causes the shaft (3) to move laterally. The invention provides for further mounting this first support plate (2) eccentrically with a second rotatable support plate (5) to increase the versatility of the lateral movement of the shaft (3).

Description

"Eccentric Displacer for Gears"

This invention relates to a means for varying the distance between gear centres of intermeshing gears.

Gears are commonly used as a means for increasing or decreasing rotational velocity. It is well known that by varying the ratio of the size or pitch circle diameter (PCD) of intermeshing gears the velocity of a driven gear and associated shaft can be controlled to an appropriate speed while maintaining the driving gear at a constant and desirable speed.

However, a problem arises when the teeth of the gears are required to intermesh and the shafts or axles of each gear, while being free to rotate, are fixed in one position. When it is sought to change the gear ratios between the fixed shafts it has generally been necessary to change both gears such that one is increased in size while the other is decreased, thereby enabling the correct interaction of the gear teeth and keeping the distance between the shafts or gear centres constant . Changing the gear on only one shaft has not been possible as the teeth of the gears do not interact appropriately and failing or slipping may occur. To overcome this undesirable situation, in the past it has been common to enable one of the shafts to be slidable or otherwise movable in a controlled manner. However, moving a shaft or axle is also associated or inherent with problems on the basis that it generally requires the movement of bearing houses and other apparatus attached to or integral with the shaft .

One such method of moving a shaft is to locate it on a slidable tray or sled, wherein the sled is free to move to respective locations which correspond to appropriate positions depending upon the size of the gear on the shaft. In such embodiments the sled or tray is generally brought to rest and held in a respective location by lugs or dowels. In use, it is found that these lugs or dowels become worn and may reduce in size or bend causing the sled or tray to come to rest in a slightly inaccurate position. Where the sled is located on a linear slide only a slight disposition of the sled and the corresponding shaft can cause significant fouling of the intermeshing teeth of the gears. Such fouling or interference in turn causes excessive wear of the gears leading to higher maintenance costs and increased down time of the associated machinery.

In other embodiments known in the past, disassembly of components, including the shaft has been required which is a cumbersome and time consuming task.

According to the invention there is provided an apparatus for varying the distance between gear supporting shafts comprising means for mounting at least one of said shafts eccentrically on a first rotatable support plate, wherein rotation of said first plate causes lateral movement of said shaft .

Preferably, said first support plate is also mounted eccentrically on to a second rotatable support plate such that rotation of said second support plate causes lateral movement of said first support plate and said shaft.

Preferably, said apparatus also comprises means for locking said first plate and said second plate each in respective first and second positions, wherein said respective first and second positions are each set apart by 180 degrees and wherein when said first and second plates are in any one of said positions, said shaft is orthogonal to a line collinear with a particular diameter of the fixed gear.

Preferably, said apparatus is included in a roll-fed labelling machine.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is a plan view of an eccentric mounting system, and

Fig.2 is a sectional view of a cutter bearing housing assembly used in a roll fed labeller which incorporates the invention.

Referring to the Figures, a gear 35 is located on a shaft 3. The shaft 3 itself is mounted on a first support plate 2 in such a way that it is located off centre of the support plate 2. Accordingly, rotation of the support plate 2 about its centre 4 causes the shaft 3 to move in a lateral direction. In particular, rotation of the first support plate 2 causes the shaft 3 to travel around a locus which circumnavigates the centre 4.

The first support plate 2 is also eccentrically mounted on a further or second support plate 5. Consequently rotation of the second support plate 5 causes the centre 4 of the first support plate 2, together with the shaft 3 to move in a lateral direction.

Rotation of both the first support plate 2 and the second support plate 5 is limited by lugs or dowels 26. In the embodiment shown in the Figures the circumference of the first support plate 2 and the second support plate 4 is slightly distorted such that one half of each plate 2, 4 is of slightly greater radius than the opposite half of each said plate, thereby causing, upon rotation, the half of each plate having the larger circumference to foul or interfere with the lugs 26.

A particular application of the invention may be found for use in roll fed labelling apparatus. Fig. 2 shows a cutter bearing housing assembly which is used in such an application. The assembly would provide a mount upon which a cutting drum is located.

Depending upon the length of each respective label in a continuous web the size of the cutter drum is required to be varied. In practice, there are three or four desirable drum sizes which correspond to label sizes which, in turn, are dependent upon bottle and can diameters commonly used as containers or utensils for carrying beverages or the like.

Many roll-fed labellers provide a gear, such as that referenced 35, which corresponds in diameter to equal or approximately equal the same size as the cutter drum diameter. Thus, it is normal for the gear 35 to be replaced with an alternative gear of a different size at such time as the cutter drum is varied. In order to affect this it was previously necessary to slide the cutter drum assembly in a lateral direction to a position which corresponded to the new gear size, a process which was enabled by providing the cutter drum assembly on a sled and sliding it on rails until it was physically stopped by lugs or dowels. Small wearing of these lugs led to a significant difference in the linear distance of the displacement of the shaft and gear 35 causing excessive wear on the gears.

However the eccentric displacing apparatus shown in the figures and described herein is inherent with the advantage of displacing the shaft 3 and gear centre 36 by means of rotational movement. In turn, this leads to the advantage that at the critical point, that is where the respective intermeshing gears are required to be finally located, a relatively large angle of further rotation corresponds with only a minimal displacement in a linear direction of the shaft 3 and gear centre 36. Thus, wearing of the lugs or dowels 26 or the edge of the larger circumferenced half of the first or second plate has minimal, if any, real effect on the location of the gear centres and resultant wear on the gears themselves.

It has also been found that use of the displacement apparatus is far more efficient than methods previously used or known.

Claims

CLAIMS; -

1 Apparatus for varying the distance between gear supporting shafts comprising means for mounting at least one of said shafts eccentrically on a first rotatable support plate, wherein rotation of said first plate causes lateral movement of said shaft .

2 Apparatus as claimed in Claim 1, wherein said first support plate is also mounted eccentrically on to a second support plate such that rotation of said second support plate causes lateral movement of said first support plate and said shaft.

3 Apparatus as claimed in Claim 2, wherein said apparatus also comprises means for locking said first plate and said second plate each in respective first and second positions, wherein said respective first and second positions are each set apart by 180 degrees and wherein when said first and second plates are in any one of said positions, said shaft is orthogonal to a line collinear with a particular diameter of the fixed gear.

4 Apparatus as claimed in any one of the preceding Claims included in a roll-fed labelling machine.