BELT CLEANER

Abstract: A cleaner for attachment to a wide belt sander, the cleaner being mounted adjacent the top roller of the belt sander. The cleaner is applied to the sanding belt only during operation of the sander.

Description: BELT CLEANER This invention relates to an abrasive belt cleaner, more particularly to the cleaning of the abrasive belt in a wide belt sanding machine. BACKGROUND OF THE INVENTION In belt sanders, it is well known that after a period of operation the surface of the abrasive belt becomes loaded or filled with particles of wood and also the resins of the wood, and in fact the belt becomes glazed and virtually ineffective in operation. One solution to this problem has been to close down the machine, remove he belt and replace the belt with a new belt, the old belt being discarded. Chemical cleaning is also known, but the most common method of cleaning the belt is to apply a block of synthetic or natural rubber, preferably crepe rubber to the surface of the belt with relative motion between the belt and the block of rubber. For small sanders, the block of rubber can be hand held, but in commercial situations and particularly for wide belt sanders it is not practical and can be a dangerous action to hold the block of rubber against the sanding belt. BRIEF DESCRIPTION OF THE PRIOR ART. One example of the use of a block of rubber is shown in U.S. Patent No.4,346,671 in which the rubber block is mounted in a frame which is periodically passed through the sanding machine. Thus the sanding operatio must be interrupted and the block of rubber passed through the machine in place of a piece of wood. However the tendency with this practice is that the operators tend to obtain the maximum time between cleaning of the belt, and thus the belt can become excessively loaded, and more than one pass of the rubber block may be necessary for effective cleaning. This is loading of the belt can be detrimental to the life of the belt, and also the cleaning is time consuming. Australian Patent Application No AU-73180/87 shows a belt cleaning device attached exteriorly to a wide belt sander which can automatically contact the cleaning block on the abrasive belt during operation of the belt sander for selected periods of time. The cleaning block is mounted in a holder and ther is provided a means for withdrawing the block from the belt, and further mean for advancing the block into contact with the belt, the further means thus overcoming the force of the withdrawing means. The movement of the cleaning block can be controlled by a timer, or by a programmable controller, but when the sanding machine is not operative the cleaning block may be in contact with the belt and provision is made to withdraw the cleaning block on starting of the machine. It is an object of this invention to provide a sanding belt cleaning unit which overcomes one or more of the disadvantages of the prior art units. It is a further object of the invention to provide a belt sanding cleaning unit which is attached interiorly of the belt sanding machine. It is a still further object of the invention to provide a belt cleaning unit in which the cleaning block is not in contact with the sanding belt when the sanding machine is not operative. It is a further object of the invention to provide a belt sander cleaning unit which while automatic in operation is of simple and economical construction. BRIEF STATEMENT OF THE INVENTION. Thus there is provided according to the invention a unit for cleaning the abrasive surface of a moving sanding belt, said unit comprising a frame for mounting on the interior of a casing of a belt sanding machine adjacent the moving belt, said frame mounting at least one air operated cylinder, said cylinder actuating a lever to which is attached a holder for the cleaning block, means for the actuation of the cylinder on the passage of material to be sanded passing through the sanding machine so that on actuation of the cylinder the cleaning block moves into contact with the surface of the moving abrasive belt. BRIEF DESCRIPTION OF THE DRAWINGS. In order to more fully describe the invention reference will now be made to the accompanying drawings in which:- FIG. 1 shows a wide belt sanding machine with the cleaning unit being shown in dotted lines. FIG. 2 is a view of the belt cleaning unit, and FIG. 3 is a view of the control system for the movement of the cleaning block. DESCRIPTION OF THE PREFERRED EMBODIMENT. Referring to FIG. 2 of the drawings, the belt cleaner comprises a pair of support brackets 1 which carry the cartridge holder 2 which is connected to a air cylinder 3 by an arm 10. The cartridge holder 2 holds the cleaning cartridge 4 which as shown is applied to the surface of the abrasive belt 6 which passes over the top roller 7 of the sanding machine. A cartridge support beam 5 is positioned so that it engages the trailing edge of the cleaning cartridge to prevent or substantially eliminate any vibration of the rubber cartridge, the cartridge support beam 5 being carried by beam support brackets 8 attached to the support brackets 1. The cartridge holder is supported on axles 11 mounted in bearings attached to the support brackets 1. The right hand bracket 1 as shown in FIG. 2 is cut away so that the relationship between the cleaning cartridge 4 and the top roller 7 can be seen. The cartridge is shaped and positioned so that the cleaning pressure is applied radially to the roller. The support beam 5 has its surface 12 also generally radially of the roller and is positioned so that its longitudinal edge 13 would contact the surface of the cartridge 4 immediately adjacent the surface of the belt 6. Thus the axle 11 of the cartridge holder is displaced laterally of the axis of revolution of the upper roller 7 so that the cartridge is then applied generally radially to the roller 7. As shown in FIG. 1 the unit is attached to a sanding machine. When the unit is attached the support brackets are bolted to the top roller bearing housings, or to the top roller supporting beam, and so the unit oscillates with the top roller to thus remove the possibility of vibration. It is common practice for the upper roller to be mounted in such a manner that the roller can oscillate. This is necessary to ensure that the belt tracks correctly on the rollers, The moveme of the belt is sensed by sensors, and when it runs off track, the sensors are connected to means which then cause the bearings on which the roller is mounted to be adjusted to tilt the roller so that the belt is caused to track bac to its correct position. Thus as the cleaning unit is mounted on the bearing housings of the top roller, the cleaning unit will thus move with the roller so ensuring that the pressure of the cleaning unit is applied evenly along the whole length of the roller. In accordance with the invention the cleaning unit is only applied to the abrasive belt when desired, preferably during a sanding operation. Thus the are provided on the sanding machine, preferably on the feeding table 15 a photo electric switch to detect the timber as it exits the sanding operation. Th is connected to a controller 18 supplied with compressed air through air supply line 19. The controller 18 then supplies compressed air through lines 20 and 21 to the air cylinder 3. Thus when the machine is stationary or when it is operating, the cleaning cartridge is held away from the abrasive belt. However when material to be sanded is presented to the machine the exit switch is activated so that the air cylinder moves to apply the cleaning cartridge to the abrasive belt. The photo electric switch has an adjustable timer built in, after the predetermined timer has elapsed the switch cuts out which will cause the cleaning cartridge to be retracted. In this way the belt is continually cleaned only when the machine is actually sanding, the belt is ke continually clean, thus greatly extending the life of the belt. As shown in FIG. 1 the cleaning unit is mounted inside the casing of the sanding machine, and the only requirement is that a small opening be made in the top cover so that the arm 10 will pass through to be connected to the ai cylinder which can be mounted on a suitable bracket ( not shown) attached t the sander although in many cases the air cylinder can be made to fit inside the sanding machine casing. While the cleaning unit is preferably operated automatically, it is to be realise that the belt cleaner can be operated manually. All that is required is that the fluid cylinder be provided with a manual air valve which can be operated as desired to clean the sanding belt or a series of mechanical levers can be use to replace the air cylinder. Thus it can be seen that there is provided according to the invention a belt cleaner for a wide belt sander. The unit can easily be modified for various makes of sanders, and the cleaning cartridge can easily be replaced by sliding out the used cartridge from the holder and inserting a new cartridge. This can easily be done via a removable panel on the sanding machine, or a closable opening in the casing of the machine. It is to be noted that while the invention is a cleaning unit which can be supplied and attached to existing belt sanders, belt sanders can be produced which have the cleaning unit fitted thereto during the production thereof. Although one form of the invention has been described in some detail, it is to be realised that the invention is not to be limited thereto, but can include variations and modifications falling within the spirit and scope of the invention.

Claims: 1. A cleaning unit for cleaning the abrasive surface of a moving sanding belt in a sanding machine, said unit comprising a cartridge holder for mounting in the interior of a casing of the belt sanding machine adjacent the moving belt, at least one fluid operated cylinder connected to said cartridge holder , means to actuate the cylinder on the passage of material to be sanded passing through the sanding machine so that on actuation of the cylinder the cleaning block moves into contact with the surface of the moving abrasive belt. 2. A cleaning unit as defined in claim 1 wherein the cartridge holder is adapted to be mounted to the bearing housings of the top roller of the belt sander so that the cartridge holder oscillates therewith. 3. A cleaning unit as defined in claim 1 wherein the cartridge holder contains a removable cleaning cartridge, the cartridge holder being pivoted in bearings fixed to a support bracket to be mounted on the bearing housings of the top roller of the belt sander or to the steel beam supporting the top roller. 4. A cleaning unit as defined in any one of the preceding claims wherein the fluid operated cylinder is an air cylinder controlled by a control unit operated by micro switches or photo electric switches on the entry and/or exit ends of the belt sander so that the cleaning cartridge is only applied to the sanding belt during a sanding operation. 5. A cleaning unit as defined in any one of claims 1 to 3 wherein the fluid cylinder is manually controlled by a control valve or a series of mechanical levers. 6. A cleaning unit as defined in claim 3 wherein the cleaning cartridge is applied to the sanding belt generally radially of the top roller over which the sanding belt passes, a support beam mounted on said support brackets and extending adjacent the sanding belt and in contact with the cleaning cartridge to support the edge of the cartridge in contact with the sanding belt. 7. A wide belt sanding machine including a sanding belt passing over a top roller supported in bearings mounted on bearing supports in the casing of the machine, said sanding machine including a cleaning cartridge pivotally mounted on support brackets attached to the said bearing supports, means mounted on the sanding machine pivoting said cleaning cartridge to apply and remove the cleaning cartridge from the sanding belt, and a cartridge support beam mounted on said support brackets, said support beam being positioned adjacent said cleaning belt in contact with the cleaning cartridge. 8. A wide belt sanding machine as defined in claim 7 characterised in that the means to apply and remove the cleaning cartridge comprise a fluid cylinder, said fluid cylinder being controlled by photo electric switches or micro switches on either the entry and/or exit portions of the sanding machine whereby the cleaning cartridge is only applied during a sanding operation. 9. A cleaning unit for cleaning the sanding belt of a belt sander substantially as hereinbefore described with reference to the accompanying drawings.

Inventors: SMITH ROBERT KEITH, SMITH, ROBERT, KEITH
Applicants: SMITH ROBERT KEITH, SMITH, ROBERT, KEITH
Application year: 1992
Main classification: B08B1
IPC codes: B24B53