Belt sander

Abstract

Belt grinding device for surface processing, comprising - a first deflection pulley (14) which is rotatably mounted in a housing (12) and can be set in rotation by means of a drive unit (16), - one or more distal second deflection rollers (20) which are rotatably mounted by means of a bearing device (18) and the bearing device (18) is connectable to the housing (12), wherein an endless abrasive belt (22) can be guided over the first and the distal second deflection roller (14, 20) and driven by means of the first deflection roller (14), and - the storage device (18) has one or more guide sections for guiding the endless sanding belt (22) between the first and the distal second deflection roller (14, 20), wherein the distal second deflection pulley (20) is adjustable along a longitudinal axis (A) of the bearing device (18) between a first end position and a second end position, the storage device (18) has a first sub-section (30) and a second sub-section (32), wherein the first sub-section (30) is connectable to the housing (12) and the second sub-section (32) is displaceable relative to the first sub-section (30) along the longitudinal axis (A) of the storage device (18) between the first and second end positions and the distal second deflection roller (20) is mounted in the second sub-section (32), the second sub-section (32) is pre-tensioned into the first end position by means of a pre-tensioning element, the second sub-section (32) is held in the second end position or an intermediate position between the first and second end positions by means of a holding mechanism (52), and The retaining mechanism (52) has a locking bolt (54) which can be inserted into a recess (50) of the first or second sub-section (30, 32), characterized in that the locking bolt (54) interacts with a return element (56) such that the locking bolt (54) is inserted into the recess (50) against the return force of the return element (56) and is pressed against the side wall of the recess (50) by the preload of the second sub-section (32), thereby generating an adhesion that prevents the locking bolt (54) from being returned to its initial position by the return element (56), and the locking bolt is returned to its initial position by the second sub-section (32) being displaced against the direction of action of the preload element, releasing the adhesion and the locking bolt (56) being returned from the recess (50) to its initial position by the return element (56).and thus the second sub-area is pushed towards the first end position by the preload force of the preload element.

Description

[0001] The present invention relates to a belt grinding device for machining surfaces, comprising a first deflection roller which is rotatably mounted in a housing and can be set in rotation by means of a drive unit, one or more distal second deflection rollers which are rotatably mounted by means of a bearing device, and the bearing device can be connected to the housing, wherein an endless grinding belt can be guided over the first and distal second deflection rollers and can be driven by means of the first deflection roller. Such a belt grinding device, which has the features of the introductory part of claim 1, is described in DE 41 43 432 C2. Another belt grinding device is known from US 6 648 737 B2. DE 44 24 022 A1 relates to a hand-held power tool with a locking device for a ring gear driven by its rotary drive.Belt grinding devices of this type, in which the distal second deflection pulley forms a free end and is at a certain distance from the housing, are also known as grinding swords and are used to machine surfaces that are difficult to access. Examples of this could be the surfaces of objects that are arranged in a niche with corners at a short distance from adjacent objects. Depending on the design of the belt grinding device, the distance of the distal second deflection pulley from the housing can vary. As the distance increases, however, the problem arises that the endless grinding belt no longer runs along the common tangent of the first and second deflection pulleys between the deflection pulleys, but deviates from this radially inwards further and further and takes on a concave course. This deviation orThe concave curvature of the endless grinding belt results in, on the one hand, planar surfaces to be machined no longer achieving the desired level of planarity after machining, and, on the other hand, such belt grinding devices cannot create planar surfaces from non-planar surfaces. In either case, a post-processing step with a different tool is necessary, which is laborious and costly.

[0002] Furthermore, changing an endless sanding belt is a complex process. With the sanding blades mentioned above, at least one pulley must usually be loosened with a tool, the endless sanding belt replaced, and then the pulley returned to its original position. Sometimes it's difficult to apply the necessary tension to the endless sanding belt.

[0003] The object of the present invention is therefore to provide a belt grinding device that counteracts the problems discussed. In particular, a belt grinding device is to be provided that is suitable for treating planar surfaces or for creating planar surfaces and also allows for easy replacement of the endless grinding belt.

[0004] This object is achieved with a belt grinding device as mentioned above, which has the features of claim 1. In this device, the bearing device has one or more guide sections for guiding the endless grinding belt between the first and second deflection rollers. The guide sections are designed such that they prevent the endless grinding belt from constricting radially inward between the two deflection rollers or at least noticeably reduce the constriction. The guide sections can themselves be designed as deflection rollers that engage the endless grinding belt on its inner side and guide the endless grinding belt. As a result, the constriction of the endless grinding belt and consequently the deviation from the ideal planar course between the two deflection rollers is reduced. With the belt grinding device according to the invention, planar surfaces can be treated without their planarity being lost during treatment.Furthermore, non-planar surfaces can be treated so that they are planar after treatment.

[0005] Ideally, the guide sections are located between the first and second deflection pulleys. This allows for a compact design of the belt grinding device, and also ensures that the guide sections are positioned precisely where the deviation from the planar path occurs. This allows the endless grinding belt to be guided directly without complex constructions, counteracting constriction. The additional material and manufacturing costs required for this are kept to a minimum.

[0006] In a further development, the guide sections are designed as guide plates. Guide plates are advantageous from a manufacturing perspective and can extend across almost the entire area between the two deflection pulleys, so that the endless sanding belt is guided almost completely. When machining surfaces, the guide plates apply a counterforce to the inside of the endless sanding belt, preventing it from deflecting inward. The endless sanding belt thus runs almost planar between the two deflection pulleys.

[0007] In the belt grinding device according to the invention, the distal second deflection roller is adjustable along a longitudinal axis of the bearing device between a first end position and a second end position. This design makes it very easy to change the endless grinding belt. To do so, the distal second deflection roller must be moved from the first toward the second end position, which relieves the tension on the endless grinding belt so that it can be removed from the two deflection rollers. A new endless grinding belt is then placed around the two deflection rollers, and the distal second deflection roller is returned to the first end position. The design effort is minimal, so that manufacturing costs remain manageable.

[0008] In the belt grinding device according to the invention, the bearing device has a first sub-area and a second sub-area, wherein the first sub-area is connectable to the housing and the second sub-area is displaceable relative to the first sub-area along the longitudinal axis of the bearing device between the first and second end positions, and the second deflection roller is mounted in the second sub-area. In this embodiment, the bearing of the second deflection roller does not need to be displaceable, which reduces the design effort. It is sufficient if the first sub-area is telescopically displaceable relative to the second sub-area. This telescopic displaceability is easy to implement in terms of manufacturing technology.

[0009] According to the invention, the second partial area is pre-tensioned into the first end position by means of a pre-tensioning element. The first end position is selected such that the endless sanding belt is optimally pre-tensioned. The user does not have to worry about the correct pre-tension because the pre-tensioning force applied by the pre-tensioning element is adapted to the endless sanding belt used. The distal second deflection roller or the second partial area does not necessarily have to be moved completely into the first end position. If endless sanding belts are used that are operated with a lower pre-tension, the pre-tensioning element is adjusted accordingly. In this case, the distal second deflection roller is pushed towards the first end position, but does not have to reach this position and can assume an intermediate position between the first and second end positions.

[0010] Furthermore, the pre-tensioning element further simplifies changing the endless sanding belt. The user simply needs to move the distal second deflection pulley or the second section toward the second end position against the direction of action of the pre-tensioning element, which reduces the tension on the endless sanding belt and allows it to be replaced. After attaching the new endless sanding belt, the distal second deflection pulley only needs to be relieved of tension, and is then pushed toward the first end position using the pre-tensioning element.

[0011] According to the invention, the second sub-region can be held in the second end position or an intermediate position between the first and second end positions by means of a holding mechanism. The holding mechanism further facilitates the replacement of the endless sanding belt. If the second sub-region or the distal second deflection roller is held in the second end position or in an intermediate position, the user does not need to simultaneously apply a force counter to the effective direction of the pretensioning element when changing the endless sanding belt and can easily release the endless sanding belt from the deflection rollers. The force counter to the effective direction of the pretensioning element is applied by the holding mechanism, so that the user can concentrate fully on replacing the endless sanding belt, which can be carried out more easily and quickly.Furthermore, it is easier to position the endless sanding belt correctly on the pulleys, thus reducing incorrect loading and damage to the endless sanding belt.

[0012] In addition, the holding mechanism has a locking pin that can be inserted into a recess in the first or second partial area. The locking pin can only be inserted into the recess when the second partial area has been moved from the first end position towards the second end position or completely into the second end position. When the locking pin engages in the recess, the locking pin and the recess interact to apply a holding force counter to the direction of action of the preload element and the second partial area is held in an intermediate position or the second end position. For this purpose, the locking pin can preferably be moved perpendicular to the direction of action of the preload element. This design of the holding mechanism is structurally simple to implement, so that manufacturing costs are kept low.

[0013] The locking pin also interacts with a return element. Once inserted into the recess, the locking pin rests against the side wall of the recess. The resulting friction or adhesion is greater than the return force of the return element. If the second section or the distal second deflection roller is moved slightly against the direction of action of the pre-tensioning element, the friction is eliminated and the locking pin returns to its original position, in which it does not engage with the recess. This removes the fixation of the second section, which is then pushed towards the first end position by the pre-tensioning force of the pre-tensioning element. Consequently, the endless sanding belt is tensioned. In this embodiment, the holding mechanism can be unlocked by applying renewed load to the second deflection roller, which further facilitates changing the endless sanding belt.

[0014] In a preferred further development, the recess is arranged in a guide element, which is connected to a stop against which the preloading element abuts. The guide element serves to transmit the movement of the second sub-area in such a way that the holding mechanism can be arranged in a structurally advantageous manner. If a spring is used as the preloading element, the guide element can also serve as a guide pin onto which the spring is placed. In this respect, the guide element serves a simplified construction. Furthermore, the guide element supports the guidance between the first and second sub-areas.

[0015] In a further development, the distal second deflection pulley has a central taper in which a bearing section of the bearing device is arranged. In this development, the bearing section is arranged centrally, so that the deflection pulley can be designed wider than the bearing device. Consequently, it is possible for the endless grinding belt to completely cover the bearing device and to be laterally flush with the bearing device or the guide sections or to protrude beyond them. This development has the advantage that hard-to-reach surfaces in corners and niches can be processed more effectively, since no components of the bearing device interfere.

[0016] In a further development of the belt grinding device according to the invention, two or more distal second deflection rollers are provided, between which one or more bearing sections of the bearing device are arranged. This also ensures that the bearing sections can be arranged medially towards the longitudinal axis, and the two distal second deflection rollers, which are outermost with respect to the axis of rotation, represent the laterally outermost components. Again, the endless grinding belt can completely cover the bearing device and be laterally flush with the bearing device or the guide sections, or protrude beyond them. This further development has the advantage that hard-to-reach surfaces in corners and niches can be processed more effectively, since there are no components of the bearing device to interfere.

[0017] The housing preferably has an extraction port to which a suction hose can be connected. This allows the sanding dust generated during surface treatment to be extracted and collected in a container, preventing it from being released into the air. This improves the user's work safety, as the hazardous sanding dust cannot enter the lungs. Furthermore, cleaning after surface treatment is reduced, as less dust settles in the area surrounding the treated surfaces.

[0018] Ideally, the belt grinder has two or more feet. The feet allow the belt grinder to be placed on a workbench, so that the relative movement between the workpiece and the belt grinder can be generated not only by the movement of the belt grinder, but also by the movement of the workpiece. This working method is particularly suitable for machining small workpieces.

[0019] In addition, one or more of the feet are formed by a support bracket for holding the belt sander. A support bracket is advantageous for the movement of the belt sander, as it allows the user to perform the work in an ergonomically favorable manner. If the feet are formed by the support bracket, the design effort is reduced.

[0020] The belt grinding device according to the invention is described in detail below with reference to the attached figures using preferred embodiments. They show: Fig. 1 a basic plan view of a first embodiment of a belt grinding device according to the invention, Fig. 2 a basic side view of the Fig. 1 illustrated embodiment, Fig. 3 a basic side view of a second embodiment of the belt grinding device according to the invention, and Fig. 4 a basic side view of a third embodiment of the belt grinding device according to the invention.

[0021] The Fig. 1 and Fig. The first embodiment of a belt grinding device 101 according to the invention shown in Figure 2 comprises a housing 12 in which a first deflection roller 14 is rotatably mounted and driven by means of a drive unit 16 (cf. Fig. 2) is rotatable. A bearing device 18 is attached to the housing 12, on which a distal second deflection roller 20 is rotatably mounted. An endless grinding belt 22, which in Fig. 2 for the sake of clarity, can be pulled onto the first and the distal second deflection roller 14, 20 and moved by activating the drive unit 16. The bearing device 18 comprises a guide section, which in the example shown is designed as a guide plate 26 and is arranged between the two deflection rollers 14, 20 within the endless grinding belt 22. The guide plate 26 is fastened to the bearing device 18 by means of webs 28 and fastening means not shown. The guide plate(s) 26 prevent the endless grinding belt 22 from constricting inwards between the two deflection rollers 14, 20 when subjected to load. Consequently, the endless grinding belt 22 runs along a plane defined by the guide plates 26, so that planar surfaces can be machined.

[0022] The bearing device 18 comprises a first sub-area 30 and a second sub-area 32. The first sub-area 30 is fixedly connected to the housing 12, while the second sub-area 32 is adjustable relative to the first sub-area 30 along a longitudinal axis A of the bearing device 18. For this purpose, the second sub-area 32 has guide arms 34 with elongated holes 36, in which guide pins 38 extend, which are fixedly connected to the first sub-area 30. The greater extent of the elongated holes 36 runs in the direction of a longitudinal axis A of the bearing device 18, so that the first sub-area 30 with the guide arms 34 can be displaced within the elongated holes 36 relative to the first sub-area 30 along the longitudinal axis A between a first and a second end position, which are predetermined by the elongated holes 36. An axis 40 extends between the guide arms 34, on which the distal second deflection roller 20 is mounted, as can be seen particularly well from Fig. 2 is evident. From Fig. 2 it can also be seen that the guide arms 34 widen towards the free end of the bearing device 18 in order to provide sufficient distance for receiving the distal second deflection roller 20 between the two guide arms 34.

[0023] Furthermore, a pre-tensioning element designed as a tension spring 46 is provided, which pre-tensions the second partial area 32 relative to the first partial area 30 into a first end position. In particular, Fig. 2 shows that a stop 44 is arranged between the two guide arms 34, against which the tension spring 46 abuts with its first end. The other end of the tension spring 46 abuts against the first section 30. Furthermore, Fig. 2 that the tension spring 46 is mounted on a guide element 48, which extends through the first partial region 30 and is displaceable therein along the longitudinal axis A. The guide element 48 is connected at one end to the stop 44 and has a recess 50 in the region of the opposite end, which cooperates with a holding mechanism 52. The holding mechanism 52 comprises a locking pin 54, which is displaceable in a direction perpendicular to the longitudinal axis A. The locking pin 54 cooperates with a return element 56, which forces the locking pin 54 into the starting position.

[0024] To change the endless sanding belt 22, the distal second deflection roller 20 is loaded, for example, by being pressed against an object (not shown), such as a wall. This load causes the second partial area 32 to move toward the housing 12 against the pretensioning force of the tension spring 46. The guide element 48 also follows this movement, so that the recess 50 can be brought into a position in which the locking pin 54 can engage in the recess 50. This position is shown in the Fig. 1 and Fig. 2. In order to insert the locking pin 54 into the recess 50, the user must press the locking pin 54 to overcome the restoring force of the return element 56. Once the locking pin 54 is inserted into the recess 50, the distal second deflection roller 20 can be relieved. The tension spring 46 now wants to push the second partial area 32 back towards the first end position, but this is prevented by the locking pin 54. The locking pin 54 is pressed against the side wall of the recess 50, creating an adhesion that prevents the locking pin 54 from being returned to its original position by the return element 56. Since the distance between the first and second deflection rollers 20 is reduced in this position, the endless grinding belt 22 can be removed from the deflection rollers 14, 20 and replaced with a new endless grinding belt 22.Once the replacement is complete, the distal second deflection roller 20 must be briefly loaded again to release the adhesion between the locking pin 54 and the side wall of the recess 50. As a result, the locking pin 54 is moved out of the recess 50 into its initial position by the return element 56. When the distal second deflection roller 20 is relieved of load again, the tension spring 46 moves the second partial area 32 back toward the first end position, thereby tensioning the endless grinding belt 22 and allowing it to be used to machine a surface.

[0025] In the area of ​​the end faces, the deflection rollers 14, 20 can have elevations (not shown) which serve to guide the endless grinding belt 22 laterally.

[0026] Furthermore, the housing 12 is provided with an extraction nozzle 58 to which a suction hose (not shown) can be connected. This makes it possible to generate a vacuum in the area of ​​the first deflection roller 14, so that grinding dust falling from the endless grinding belt 22 can be extracted and fed into a collection container (also not shown). For this purpose, the housing 12 has an opening 59 in the area of ​​the first deflection roller 14 to allow the passage of the grinding dust. The housing 12 is Fig. 2, the selected illustration is open downwards in the area of ​​the first deflection roller 14 to ensure access to the first deflection roller 14 for changing the endless sanding belt 22. The negative pressure in the area of ​​the first deflection roller 14 creates an air flow toward the collection container, which carries the sanding dust along.

[0027] Furthermore, the belt grinding device 101 comprises a Fig. 1, for the sake of clarity, a holding bracket 60 is provided, with which the belt sander 101 can be grasped by the user. In the example shown, the holding bracket 60 simultaneously forms one or more feet 62 on which the belt sander 101 can be placed. A third, not shown, foot 62 can be attached to the housing 12, enabling three-point support of the belt sander 10.

[0028] In Fig. 3 shows a second exemplary embodiment of the belt grinding device 102 according to the invention, which differs from the first exemplary embodiment 10 in the design of the guide arms 34. While in the first exemplary embodiment 101, two guide arms 34 are provided which widen outwards and partially encompass the distal second deflection roller 20, the second exemplary embodiment 102 has a U-shaped guide arm 34 which is connected to an extension arm 64 on which a bearing section 66 for the distal second deflection roller 20 is arranged. The bearing section 66 encompasses a central taper 68 or indentation of the distal second deflection roller 20, so that no components of the bearing device 18 are arranged outwards along the rotational axis T of the distal second deflection roller 20.In the second embodiment 102, in contrast to the first embodiment 101, the endless grinding belt 22 can be wider than the bearing device 18, wherein the endless grinding belt is also guided in this case at its lateral edges by the two deflection rollers 14, 20.

[0029] The Fig.The third exemplary embodiment of the belt grinding device 103 shown in Figure 4 also differs from the first exemplary embodiment in the design of the guide arms 34: The third exemplary embodiment 103 also has the U-shaped guide arm 34, which is connected to the boom 64, on which the bearing section 66 is arranged, which is traversed by a shaft 70 on which two distal second deflection rollers 20 are mounted. In the third exemplary embodiment 103, the endless grinding belt 22, in contrast to the first exemplary embodiment 101, can be wider than the bearing device 18, wherein the endless grinding belt is also guided at its lateral edges by the two deflection rollers 14, 20 in this exemplary embodiment. Of course, it is also possible to mount three or more distal second deflection rollers 20 on the shaft 70.

Claims

[1] Belt grinding device for machining surfaces, comprising - a first deflection roller (14) which is rotatably mounted in a housing (12) and can be set in rotation by means of a drive unit (16), - one or more distal second deflection rollers (20) which are rotatably mounted by means of a bearing device (18) and the bearing device (18) is connectable to the housing (12), wherein an endless grinding belt (22) can be guided over the first and the distal second deflection roller (14, 20) and can be driven by means of the first deflection roller (14), and - the bearing device (18) has one or more guide sections for guiding the endless grinding belt (22) between the first and the distal second deflection roller (14, 20), wherein the distal second deflection roller (20) is adjustable along a longitudinal axis (A) of the bearing device (18) between a first end position and a second end position, the bearing device (18) has a first partial region (30) and a second partial region (32), wherein the first partial region (30) is connectable to the housing (12) and the second partial region (32) is displaceable relative to the first partial region (30) along the longitudinal axis (A) of the bearing device (18) between the first and second end positions and the distal second deflection roller (20) is mounted in the second partial region (32), the second partial area (32) is prestressed into the first end position by means of a prestressing element, the second partial region (32) can be held in the second end position or an intermediate position between the first and the second end position by means of a holding mechanism (52), and the holding mechanism (52) has a locking pin (54) which can be inserted into a recess (50) of the first or second partial area (30, 32), characterized byin that the locking bolt (54) cooperates with a return element (56) in such a way that the locking bolt (54) is introduced into the recess (50) against the restoring force of the return element (56) and is pressed against the side wall of the recess (50) by the prestressing of the second partial area (32), whereby an adhesion is created which prevents the locking bolt (54) from being returned to the starting position by the return element (56), and the locking bolt is brought back to its starting position by the second partial area (32) being displaced against the direction of action of the prestressing element, the adhesion is removed and the locking bolt (56) is returned from the recess (50) into the starting position by the return element (56), and thus the second partial area is pushed in the direction of the first end position by the prestressing force of the prestressing element. [2] Belt grinding device according to claim 1, characterized bythat the guide sections are arranged between the first and the second deflection roller (14, 20). [3] Belt grinding device according to claim 2, characterized by that the guide sections are designed as guide plates (26). [4] Belt grinding device according to one of the preceding claims, characterized by that the recess (50) is arranged in a guide element (48) which is connected to a stop (44) against which the prestressing element strikes. [5] Belt grinding device according to one of the preceding claims, characterized by that the distal second deflection roller (20) has a central taper (68) in which a bearing section (66) of the bearing device (18) is arranged. [6] Belt grinding device according to one of claims 1 to 4, characterized bythat two or more distal second deflection rollers (20) are provided, between which one or more bearing sections (66) of the bearing device (18) are arranged. [7] Belt grinding device according to one of the preceding claims, characterized by that the housing (12) has a suction nozzle (58) to which a suction hose can be connected. [8] Belt grinding device according to one of the preceding claims, characterized by that the belt grinding device (10) has two or more feet (62). [9] Belt grinding device according to claim 8, characterized by that one or more of the feet (62) are formed by a holding bracket (62) for holding the belt grinding device (10).

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