WO2006006843A1

WO2006006843A1 - Belt cleaning system for a portable belt sander

Info

Publication number: WO2006006843A1
Application number: PCT/NL2005/000459
Authority: WO
Inventors: Peter Wanninkhof
Original assignee: Robert Bosch Gmbh
Priority date: 2004-07-09
Filing date: 2005-06-28
Publication date: 2006-01-19
Also published as: EP1773543A1; NL1026620C2; RU2380213C2; RU2007104926A; CN1984751A

Abstract

The invention relates to a belt cleaning system for a portage belt sander (1) which is provided with a drivable sanding belt (4), comprising a cleaning element (6), a support surface (7) for supporting the cleaning element (6), and displacing means (9) for displacing the cleaning element (6) from an inactive to an active position, wherein the cleaning element (6) is in contact with the sanding belt (4) for cleaning, wherein the support surface (7) is formed by a wall of a holder (8), and the cleaning element (6) is received in the holder (8) in the inactive position.

Description

BELT CLEANING SYSTEM FOR A PORTABLE BELT SANDER

The present invention relates to a belt cleaning system for a portable belt sander which is provided with a drivable sanding belt, comprising a cleaning element, a support surface for supporting the cleaning element, and displacing means for displacing the cleaning element from an inactive to an active position, wherein the cleaning element is in contact with the sanding belt for cleaning. The invention further relates to an assembly of a portable belt sander and a belt cleaning system, as well as to a cleaning element for such a belt cleaning system.

During use the sanding belt of a portable belt sander becomes clogged with debris. In order to prolong the lifespan of a sanding belt the surface thereof can be cleaned using a cleaning block which is usually manufactured from a synthetic or natural rubber. By holding this rubber cleaning block against the surface of the sanding belt while the sanding belt is driven, fouling can be removed from the sanding belt and discharged.

A belt cleaning system according to the preamble of claim 1 is known from American patent publication 6,036,589. The support surface of this known belt cleaning system is arranged pivotally relative to the housing of the belt sander. The cleaning block can therefore be pivoted from an inactive to an active position, wherein the cleaning element is in contact with the sanding belt for cleaning. The cleaning block is mounted on the support surface. In this known belt cleaning system the replacing of cleaning blocks is time-consuming and relatively expensive. The operation is also unsafe since the block must be pressed by hand close to the drivable sanding belt .

The present invention has for its object to provide an improved belt cleaning system of the type described in the introduction.

According to the invention the belt cleaning system is characterized for this purpose in that the support surface is formed by a wall of a holder, wherein the cleaning element is received in the holder in the inactive position. The cleaning element is stored in the holder during use, but also in the inactive situation. For replacement of the cleaning element it can suffice simply to place a new cleaning element in the holder.

For an improved cleaning of the sanding belt, pressing means are further provided at a distance from the drivable sanding belt for pressing the cleaning element against the sanding belt in the active position. It is hereby not necessary for the hand to come close to the drivable sanding belt during cleaning thereof. In a particularly advantageous embodiment, the displacing means and the pressing means are formed by a drivable toothed pinion which engages on the cleaning element. The pinion can for instance be manually rotated, whereby the cleaning element in engagement therewith is carried in the direction of the surface of the sanding belt and is also pressed thereagainst when a further rotation force is applied to the pinion.

When the cleaning element is provided on two mutually opposite sides with engaging elements for co- action with the engaging elements of a following cleaning element, at least two cleaning elements, which are in mutual engagement, can be placed at a time in the holder. At least one cleaning element is herein active in cleaning of the sanding belt, while the other cleaning element or the other cleaning elements serves or serve as spare (s) .

The cleaning element is preferably further provided on at least a side lying against the support surface with a layer reducing sliding resistance. This facilitates displacement of the cleaning element in the holder to the active position.

For a good cleaning of the sanding belt, the cleaning element is preferably manufactured from a synthetic or a natural rubber.

In order to enclose and cover the cleaning block in fully protected manner, the holder can comprise a cover element .

In advantageous manner coupling means are provided between the cover element and the cleaning block. The cleaning block can hereby be taken out of the holder together with the cover element .

According to a further embodiment, indicator means are provided which indicate the degree of wear of the cleaning block.

It is also possible to provide blocking means for blocking the insertion of the cleaning block into the holder when it exhibits a determined degree of wear. The blocking means can be combined with the above mentioned coupling means.

The invention further relates to an assembly of a portable belt sander, which is provided with a housing and a drivable sanding belt, and a belt cleaning system as specified above. The belt cleaning system can be connected releasably to the housing as a separate element or form part of the belt sander. In the latter case the holder of the belt cleaning system is mounted in or on the housing or the holder is formed by the housing. The belt sander preferably further comprises two rollers mounted in the housing which are adapted to guide the sanding belt, wherein the support surface lies at an angle relative to the plane of the sanding belt situated between the two rollers. In advantageous manner a larger area of the cleaning element is brought into contact with the sanding belt for cleaning purposes. It is recommended that the pressing means exert a pressing force on the cleaning element which is in opposite direction to the direction in which the sanding belt runs. Owing to the play of forces on the cleaning element, it will always tend to become detached from the sanding belt when the sanding belt is being driven. The cleaning element will hereby not be in contact unintentionally with the sanding belt and be able to wear away.

Finally, the invention also relates to a cleaning element for a belt cleaning element as specified above. The invention will be further elucidated on the basis of the annexed drawings. In the drawings:

Figure 1 shows a perspective view of an assembly consisting of a belt cleaning system and a belt sander according to the invention in a first embodiment, and

Figure 2 shows a cross-sectional detail view of the assembly of figure 1,

Figures 3 and 4 show two different embodiments of a cleaning element for use in the belt cleaning system according to the invention,

Figure 5 is a perspective view of a further embodiment of the assembly and the belt cleaning element according to the invention, Figure 6 shows a front view of yet another embodiment of the assembly and the belt cleaning element according to the invention,

Figures 7-10 show cross-sections of different embodiments of the assembly according to the invention, wherein the holder comprises a cover element,

Figure 8 shows an outline of the cover element of Figure 7 as according to arrow VIII in Figure 7,

Figure 11 shows a further embodiment of an assembly wherein the holder comprises a cover element, and

Figure 12 is a front view as according to arrow XII in Figure 11.

Figures 1 and 2 show a belt cleaning system 1 which forms part of a housing 2 thereof. It is possible instead for the belt cleaning system to be mounted on a belt sander as a separate element or to be connected non-releasably thereto. Holder 8 is however formed by housing 2 in the different embodiments of the figures. The figures further show a roller 3 mounted in housing 2 of the belt sander and a sanding belt 4 guided thereover. The active part of sanding belt 4 is supported by a support structure 5.

Belt cleaning system 1 comprises a cleaning block 6, a support surface 7 for supporting the cleaning block, and displacing means for displacing cleaning block 6 from an inactive to an active position, wherein cleaning block 6 is in contact with the sanding belt 4 for cleaning. Support surface 7 is formed by a wall of holder 8, wherein cleaning block 6 is received in the inactive position in holder 8.

Reference numeral 9 designates a type of manually driven gear rack mechanism which can press cleaning block 6 in the direction of and against the driven sanding belt 4. Gear rack mechanism 9 consists of a pinion 11 which engages on cleaning block 6, and a control knob 12 which lies in line with the pinion and with which pinion 11 can be rotated.

Cleaning blocks 6 shown in figures 3 and 4 are provided on two mutually opposite sides with engaging elements for co-action with the engaging elements of a subsequent cleaning block 6. The figures show two different embodiments of the engaging elements.

Cleaning block 6 is further provided on at least its side lying against support surface 7 with a layer 13 reducing sliding resistance (see figure 2) . End side surfaces 10 of cleaning blocks 6 can likewise be provided with a layer reducing sliding resistance when they are in contact with walls of holder 8. Cleaning block 6 is provided on one or more sides with a layer reducing sliding resistance, such as a smooth protective sheet of paper, so as to minimize the sliding resistance with the inner side of the holder during displacement . Figure 5 shows a further embodiment wherein cleaning block 6 is provided with an end stop 14 which cannot pass through the space between pinion 11 and support surface 7. A recess is provided in holder 8 on the side of pinion 11. End stop 14 protrudes through the recess so that at a given moment it comes into contact with pinion 11 and can descend no further into holder 8.

The remainder of cleaning block 6 will have to be removed by hand from holder 8. Although this embodiment does not operate with successive, smoothly connecting cleaning blocks 6, as shown in figures 1-4, it does have the advantage that cleaning block 6 cannot shoot out from between holder 8 and sanding belt 4. It is of course also possible to provide the end stop 14 and the recess on the side of respectively cleaning block 6 and holder 8 remote from pinion 11. In that case the recess does not continue as far as the bottom of holder 8, and end stop 14 will eventually come into contact with the wall part of holder 8, which forms the end of the recess.

Figure 6 shows an embodiment wherein, using the belt sander, sanding can take place as close as possible to an obstacle 15, cleaning block 6 is supported laterally in stable manner by housing 2 which partly forms holder 8, and wherein sanding belt 4 can be cleaned over the full width by cleaning block 6. Pinion 11 can be placed parallel to the sanding plane or at an angle β, which is substantially equal to the angle α which the cleaning block makes with the side of the belt sander. Angles Ot and β can vary between 0 and 90^° . Figures 7-11 show different embodiments wherein the holder comprises a cover element 16, 23, 27, 34 for closing the holder. In the first three embodiments coupling means 17, 18, 24, 25, 28, 29 are provided between cover element 16, 23, 27 and cleaning block 19, 22, 26. The coupling- means are provided integrally on the cover element and/or cleaning block.

Owing to these coupling means the cleaning block 19, 22, 26 can be removed from the holder in simple manner by taking off and removing the cover element 16, 23, 27.

In figure 7 the coupling means consist of arms 17 connected to cover element 16 and provided with protrusions 18 (see also figure 8) . Arms 17 and protrusions 18 co-act with recesses 21 which are arranged in cleaning block 19 and which are each provided with an end stop 20. Protrusions 18 and end stops 20 together form blocking means for blocking the insertion of the cleaning block into the holder when the block displays a determined degree of wear. When protrusions 18 of cover element 16 engage with end stops 20 of block 19, the block can be removed from the holder by simply removing cover element 16. Due to the coupling between protrusions 18 and end stops 20 the cleaning block 19 is also carried out of the holder.

In figure 9 cleaning block 22 is provided with a resilient part 24 which is connected to cover element 23 by means of a ball joint construction 25. The resilient part 24 makes it possible for block 22 to be carried in the direction of sanding belt 4.

In figure 10, as in figure 9, the coupling means are formed by a resilient part 28. Here however, the resilient part 28 is formed integrally with cover element 27. Cover element 27 is connected to cleaning block 26 by_, means of a dovetail joint 29.

Figure 11 shows an embodiment wherein a cover element 34 is also provided (see also figure 12) . No coupling means are however provided between this cover element 34 and cleaning block 6. Cleaning block 6 can be removed from the holder by inserting a finger in channel 33 of the holder. A partition wall 35 is situated between channel 33 and the channel in which block 6 is arranged. Partition wall 35 is formed integrally on cover element 34 and supports block 6 in the holder. This embodiment is further provided with a control knob 30 which is rotatable about shaft 31. Shaft 31 is in contact with pinion 32. Shaft 31 has a diameter which is smaller than the diameter of pinion 32. This construction provides a great pressing force and convenience of use due to the large diameter of the control knob on the one hand and the ratio between the diameters of shaft 31 and pinion 32 on the other. Cleaning block 6 is inserted through a rectangular opening on the outside of housing 2 of the belt sander until it runs up against the pinion 11 which protrudes slightly into holder 8. The support surface 7 supporting cleaning block 6 lies at an angle relative to the surface of sanding belt 4 located between the two rollers (wherein the one roller is not shown in the figures) . By rotating the pinion 11 the cleaning block 6 is displaced to sanding belt 4, while a pressing force opposed to the direction of running of sanding belt 4 is exerted on cleaning block 6 by applying a rotation force to pinion 11 using control knob 12. Pinion 11 herein presses itself into the elastic plastic or rubber cleaning block 6 and, when rotating, is able to displace cleaning block 6 in up and downward direction, and to allow it to slip when the resistance becomes too great. As stated, cleaning block 6 can be moved onto sanding belt 4 using control knob 12. Fouling between the grains of the sanding belt can be removed by pressing cleaning block 6 further onto the then running sanding belt 4. The fouling is removed and discharged. During each belt cleaning the cleaning block 6 wears and melts until it has reached a minimum length. At this length the pinion 11 no longer drives cleaning block 6. The abraded and fouled material slips under support surface 7 and is discharged on the front side of the belt sander. It is important that the front wall of holder 8 reaches just above sanding belt 4 in order to benefit from cleaning block 6 as long as possible and to prevent too large a piece of cleaning block 6 from slipping away between this wall and sanding belt 4.

A similar cleaning block can be placed on top of the abraded cleaning block. This must be pressed inward such that pinion 11 engages thereon. It is possible to continue repeating the replenishing process . The engaging elements herein ensure a stable continuity of cleaning blocks 6 and a smooth or continuous replacement of a worn cleaning block 6 by a new one. In the transition situation pinion 11 engages on both the already worn block and the replacement block. The new block is also able to press the worn block onto the belt, so that the cleaning action is maintained.

Claims

1. Belt cleaning system for a portable belt sander which is provided with a drivable sanding belt, comprising a cleaning element, a support surface for supporting the cleaning element, and displacing means for displacing the cleaning element from an inactive to an active position, wherein the cleaning element is in contact with the sanding belt for cleaning, characterized in that the support surface is formed by a wall of a holder, wherein the cleaning element is received in the holder in the inactive position.

2. Belt cleaning system as claimed in claim 1, further comprising pressing means arranged at a distance from the drivable sanding belt for pressing the cleaning element against the sanding belt in the active position.

3. Belt cleaning system as claimed in claim 1 or 2, wherein the displacing means and the pressing means are formed by a drivable toothed pinion which engages on the cleaning element.

4. Belt cleaning system as claimed in any of the claims 1-3, wherein the cleaning element is provided on two mutually opposite sides with engaging elements for co-action with the engaging elements of a further cleaning element .

5. Belt cleaning system as claimed in any of the claims 1-4, wherein the cleaning element is provided on at least its side lying against the support surface with a layer reducing sliding resistance.

6. Belt cleaning system as claimed in any of the claims 1-5, wherein the cleaning element is manufactured from a synthetic or natural rubber.

7. Belt cleaning system as claimed in any of the claims 1-6, wherein the holder comprises a cover element.

8. Belt cleaning system as claimed in claim 7, wherein coupling means are provided between the cover element and the cleaning block.

9. Belt cleaning system as claimed in any of the claims 1-8, further comprising indicator means which indicate the degree of wear of the cleaning block.

10. Belt cleaning system as claimed in any of the claims 1-9, further comprising blocking means for blocking the insertion of the cleaning block into the holder when it exhibits a determined degree of wear.

11. Assembly of a portable belt sander, which is provided with a housing and a drivable sanding belt, and a belt cleaning system as claimed in any of the claims 1-10.

12. Assembly as claimed in claim 11, wherein the belt cleaning system is connected releasably to the housing.

13. Assembly as claimed in claim 11, wherein the holder of the belt cleaning system is mounted in or on the housing or is formed by the housing.

14. Assembly as claimed in any of the claims 11-13, wherein the belt sander comprises two rollers mounted in the housing which are adapted to guide the sanding belt, wherein the support surface lies at an angle relative to a plane of the sanding belt situated between the two rollers.

15. Assembly as claimed in any of the claims 11-14, wherein the pressing means exert a pressing force on the cleaning element which is in opposite direction to the direction in which the sanding belt runs.

16. Cleaning element for a belt cleaning element as claimed in any of the claims 1-10.