Technical Field

The invention relates to a conveyor belt cleaner assembly for use on a conveyor belt apparatus, and to a conveyor belt apparatus comprising the assembly.

Background

Conveyor belts are used in a wide variety of industries to transport solid material. In some cases liquid material may also be included with the solid material, which can make transport more challenging.

Conveyor belts generally have an endless loop formation, wherein an upper surface of the conveyor belt carries solid material to be transported, which loops back as a lower surface after passing around an end roller. In general the solid material carried by the upper surface is held in place by gravity. Likewise, gravity causes the solid material to fall off the conveyor belt as it moves past an end roller. However in many industries it is not sufficient to rely on gravity to release all of the solid material from the conveyor belt, particularly where some liquid material is also present.

To address this, so-called conveyor belt cleaners are employed which act to scrape the lower surface of the conveyor belt to assist in the removal of solids that have not fallen off the conveyor belt due to gravity alone.

A common arrangement of conveyor belt scraper comprises a horizontal support bar wherein a scraper blade is mounted upon the horizontal support bar arranged to provide a scraping action on the surface of a conveyor belt.

Such conveyor belt cleaners comprises a scraping blade that maintains a small amount of pressure on the lower surface of the conveyor belt, so as to maintain good contact with the belt. Typically such scraping blades are made of a hard-wearing material such as tungsten carbide and the like. However, such scraping blades inevitably suffer from a significant rate of wear and this has the effect of reducing the amount of pressure exerted onto the surface of the conveyor belt, reducing its scraping performance. One way of ensuring that there is a constant scraping force applied to the scraper is to have a resilient connection between the scraping blade and a rigid supporting structure.

For example, US 3,841 ,470 discloses a cleaner for a conveyor belt which has a plurality of cleaner blades, each of which are mounted on a horizontal support bar by a respective resilient member. Also, US 6,227,350 discloses a cleaner for a conveyor belt which has a plurality of cleaner blades, each of which are mounted on a horizontal support bar by a shared pressurised fluid, that ensures each cleaner blade exerts the same pressure on a conveyor belt in use.

However, the effectiveness of the resilient connection also deteriorates over time and eventually some adjustment of the rigid supporting structure is required, which typically involves the manual adjustment of a nut-and-bolt fixing. Conventionally, such adjustment is carried out by physically repositioning the blade, carried out by an operator. This could be by adjusting a screw or not, or by applying a form of ratchet system. However such adjustments are time consuming and dependent upon regular checking of the blades of cleaners.

Additionally, the use of elastomeric elements can limit the applicability of any scraper to environments where corrosive materials are being handled.

Improvements in this area would therefore be desirable.

Detailed Description of the Invention

In a first aspect, the invention relates to a conveyor belt cleaner assembly, for scraping the surface of a conveyor belt, the assembly comprising a horizontal support bar having a first end and a second end, the horizontal support bar being mounted on a first end support mount and a second end support mount, the horizontal support bar being moveable with respect to the first and second end mounts, so as to be moveable towards and away from the surface of a conveyor belt to be scraped in use, wherein a scraper blade is mounted upon the horizontal support bar arranged to provide a scraping action on the surface of a conveyor belt, characterised in that the horizontal support bar is biased towards a position towards the surface of a conveyor belt to be scraped in use by pressurised fluid. Preferably the horizontal support bar is vertically moveable towards and away from the surface of the conveyor belt. It is also preferred that the biasing is applied in a vertical upwards direction to provide vertical upwards movement of the horizontal support bar.

By arranging for the horizontal support bar to be vertically moveable and biased towards the conveyor belt surface, this allows for a constant pressure on the surface of the conveyor belt. Additionally, as the scraper wears down or other mechanical changes occur, the pressurised fluid will ensure that constant upwards pressure is maintained without the need for manual adjustment of the horizontal bar position by an operator. Additionally, since resilience in the system is provided by the fluid pressure acting on the horizontal bar, the scraper blade does not need to be attached to the horizontal bar by an elastomeric material, and can be rigidly attached, which means that the entire assembly can be made from materials that are more resistant to corrosion.

It has been found that a gas spring provides a convenient way of delivering a constant upwards force onto the horizontal support bar and would not be affected by a build-up of dirt or corrosion and provides a consistent force over time. Thus, preferably the horizontal support bar is biased towards a position towards the surface of a conveyor belt to be scraped in use by at least one gas spring.

Preferably a first gas spring is provided on the first end support mount and a second gas spring is provided on the second end support mount.

In order for the horizontal support bar to provide a consistent upwards force on the belt, it is preferable that the horizontal support bar is vertically slideably mounted on the first and second end supports.

As discussed, pressurised gas, e.g. provided by a gas spring, exerts a linear upwards force on the horizontal support bar. It may be desirable to be able to disengage the gas spring from the horizontal support bar, in order to remove this upwards force, for example when cleaning or replacing a blade. It is therefore preferable that the gas spring acts on a cammed surface, so that rotation of the cammed surface can cause the disengagement of the upwards force from being transferred to the horizontal support bar. The cammed surface is preferably attached to the horizontal support bar, and thus preferably the horizontal support bar is rotatably mounted on the first and second end supports.

By arranging for the horizontal support bar to be rotatably mounted, the scraper blade can be conveniently rotated away from a cleaning position to a maintenance position, providing an easily accessible space for cleaning and maintenance.

By means of a cammed surface, any rotation of the horizontal support bar may also cause the removal of the upwards biasing force from the horizontal support bar. In this way, a single rotational movement of the bar can move it from a cleaning position to a maintenance position in a single combined rotational and vertical movement.

Preferably the assembly comprises a handle means to enable an operator to move the position of the horizontal support bar. This is particularly advantageous when combined with the horizontal support bar being vertically slideably moveable and/or rotatably moveable, as discussed below. Alternatively, the movement of the horizontal bar may be motorised.

The present invention therefore provides a convenient way in which a constant upwards force can be applied to a scraping blade without the need for regular manual adjustment. It has also been found that a single blade spanning the width of a conveyor belt provides an effective contact and scraping action over the whole conveyor belt. Thus a simplified construction involving a single scraping blade is preferred.

The conveyor belt cleaner assembly may be fitted to a conveyor belt apparatus in known manner without any significant modifications of existing conveyor belt lines being necessary.

Thus, in a second aspect, the invention relates to a conveyor belt apparatus comprising a conveyor belt cleaning assembly described herein. Typically, the arrangement is such that the horizontal support bar is positioned beneath a horizontal section of the conveyor belt, so that any vertical upwards movement of the horizontal support bar brings any attached scraper into contact with the conveyor belt surface. Additionally, any upwards biasing provides a constant upwards pressure onto the conveyor belt surface, as discussed above. The invention will now be illustrated, byway of example, and with reference to the following figures, in which:

Figure 1 is perspective view of a conveyor belt apparatus in combination with a conveyor belt cleaner assembly according to the present invention.

Figure 2 is a side sectional view at a slight angle, of the conveyor belt apparatus shown in figure 1.

Figure 3 is a perspective view of a conveyor belt cleaner assembly according to the present invention, in a scraping position.

Figure 4 is a perspective view of the conveyor belt cleaner assembly shown in figure 3 in a cleaning and maintenance position.

Figure 5 is a side sectional view through a first end support mount of the conveyor belt cleaner assembly shown in figure 3.

Figure 6 is a side sectional view through an alternative end support mount.

Turning to the figures, figures 1 and 2 show a conveyor belt apparatus 10 with a conveyor belt cleaning assembly 12 fitted to it. The conveyor belt apparatus 10 comprises a conveyor belt 14 having an upper forwardly travelling surface 16 and a lower return run surface 18 and being driven by roller 20.

The conveyor belt cleaner assembly 12 comprises a horizontal support bar 22 and a first end support mount 24 and a second end support mount 26. Mounted on the horizontal support bar 22 is a scraper blade 28. The scraper blade 28 is rigidly connected to the horizontal support bar 22 via support plates 30 and 32. The entire assembly 12 is corrosion resistant and the structural components made from stainless steel or nylon.

As can be seen, conveyor belt cleaner assembly 12 is positioned beneath the conveyor belt apparatus 10, so that the scraper blade 28 is in contact with the lower return run surface 18 of the conveyor belt 14. In use, as the conveyor belt apparatus 10 operates to rotate roller 20, and solid material (not shown) is carried on top of the upper forwardly travelling surface 16. The majority of the solid material leaves the surface of the conveyor belt 14 due to gravity as the belt 14 travels around roller 20. Any solid material that remains adhered to the surface of the conveyor belt 14 on the lower return run surface 18 are then scraped off from the surface 18 by scraper blade 28.

Figures 3 to 5 show the conveyor belt cleaner assembly 12 isolated from the conveyor belt apparatus 10. The horizontal support bar 22 is mounted at its first and second ends to first end support mount 24 and second end support mount 26 respectively.

It will be noted that the ends of horizontal support bar 22 extend beyond the first 24 and second 26 end support mounts. Attached to the ends of the horizontal support bar are cammed blocks 54, 56. It can also be seen that gas springs 64, 66 are mounted on support platforms 40. Extending from each cammed block 54, 56 is a handle 60, 62.

First end support mount 24 comprises first vertical support plate 34 and second vertical support plate 36. The first 34 and second 36 vertical support plates are connected at their upper ends by metal block 38 and connected at their lower ends by support platform 40. Attached to the interior surfaces of the first 34 and second 36 vertical support plates are a pair of nylon travel surfaces 42, each comprising a vertical slot. Positioned between the pair of nylon surfaces 42 is a nylon bush 50 that is positioned within the slots in the pair of nylon travel surfaces 42 allowing the bush 50 to travel vertically within the end support mount 24. Second end support mount 26 is a mirror image to the first end support mount 24, and therefore does not need to be separately described.

The nylon bush 50 comprises a cylindrical hole 51 in its centre, lined with a stainless steel cylinder 52. One end of horizontal support bar 22 passes snugly within the cylinder 52. Thus, by virtue of the mounting within the cylinder 52, the horizontal support bar 22 is rotatably mounted within the end support mount 24. Also, by virtue of the mounting of the nylon bush 50, the horizontal support bar 22 is also slideably mounted on the first end support 24.

In use, as shown in figure 3, gas springs 64, 66 act to apply upwards pressure onto cammed blocks 54, 56 respectively. This is translated to upwards force acting on both ends of horizontal support bar 22. By virtue of the horizontal support bar 22 being vertically slideably mounted in first 24 and second 26 end supports, the horizontal support bar is biased to an upwards position. Upwards movement is limited to the ends of the vertical slots in the nylon travel surfaces 42, however before that limit is reached, the arrangement is such that the scraper 28 contacts the conveyor belt 14 and applies pressure thereto, the reaction to which prevents further vertical upwards movement of the horizontal support bar 22

As the scraper blade wears away in use, a constant pressure is nevertheless exerted onto the conveyor belt due to the action of the gas springs 64, 66.

Ultimately, the scraper blade 28 will need replacing, or possibly the assembly may require cleaning or other maintenance issues such as removing a blockage or trapped article.

In the case of cleaning or maintenance being required, the movement of the conveyor belt will be stopped and an operator will actuate one or both of handles 60, 62, in order to place the assembly 12 into a clean and maintenance position, as shown in figure 4.

As the handles 60, 62 are actuated, by virtue of the horizontal support bar 22 being rotatably mounted, this causes rotation of the horizontal support bar, which in turn rotates the attached scraper blade 28, 30, 32. As shown in figure 4 this could involve a 90° rotation, or similar degree of movement.

As the gas springs act on cammed blocks 54, 56 the transfer of the upwards force from the gas springs is reduced until it is removed completely once the horizontal support bar has reached the position shown in figure 4. Thus, not only is the scraper blade 28, 30, 32 rotated away from the conveyor belt but also the horizontal support bar moves downwards somewhat, as permitted by the vertical slots in the nylon travel surfaces. This leaves an accessible space for an operator to replace a scraper blade and/or to perform a cleaning or maintenance operation.

Once the cleaning and maintenance has been completed, an operator can actuate handles 60, 62 to return the assembly to the position shown in figure 3 and the conveyor belt apparatus 10 can be restarted.

Figure 6 shows a side sectional view through an alternative first end support mount 80 showing the detail of a cammed block 82. Shown is a gas spring 84 having a moveable shaft 85 with a ball bearing 86 at its end. In the figure the conveyor belt scraper is shown in its scraping position. The cammed surface 88 comprises an indent 90 that matches the profile of the ball bearing 86 to maintain the conveyor belt scraper in the scraping position. The thickness of the cammed surface 88 varies gradually with respect to the centre of rotation, providing the cammed surface function, as will be described.

When it is desired to move the conveyor belt scraper into a cleaning and maintenance position, cammed block 82 is rotated in a clockwise or anticlockwise manner. This is met by an initial resistance by the ball bearing leaving the indent 90 as the shaft 85 is pressed into the gas spring 84. As the cammed block 82 is further rotated the shaft 85 gradually leaves the gas spring 84 until the ball bearing bears against the final position 92 on the cammed surface 88. At this point the shaft 85 has reached its maximum position and no longer applies an upwards force onto the horizontal bar 22. This not only leaves an accessible space for an operator to replace a scraper blade and/or to perform a cleaning or maintenance operation but also ensures that any upwards force on the horizontal bar 22 is removed to aid cleaning and to increase the space available.