Grinding tool with a grinding element with internal drive

Abstract

Grinding tool comprising a handle (1) with a gripping surface (2), wherein a rotatably driven grinding body (3) is attached to the handle (1), the grinding body having a receiving space (4) in which a drive unit (5) for rotating the grinding body (3) is arranged, wherein the grinding body (3) is mounted on its central axis of rotation (7) on an arm (8) attached to the handle (1), characterized in that the arm (8) is designed as a pivoting arm which is resiliently movable back and forth against a spring force of a spring on the pivot bearing (8a).

Description

[0001] The present invention relates to a grinding tool according to claim 1. The present invention therefore relates to a grinding tool with a rotatably driven grinding body, which has a receiving space in which a drive unit for driving the grinding body is arranged.

[0002] In the prior art, a wide variety of different designs of grinding tools are known.

[0003] Grinding tools generally have a movable grinding element with which the surface to be processed is ground or machined. In the prior art, for example, DE 7605557 U discloses a grinding tool with a cylindrical holder for receiving a clampable, band-shaped abrasive carrier, which is held by means of a transverse and inwardly directed fold through a longitudinal slot arranged in the cylinder shell and a further longitudinal slot located in a clamping hub of the cylinder.

[0004] These types of grinding cylinders are used for grinding a wide variety of materials, such as wood, leather, plastic, and metal. Accordingly, different types of abrasive carriers with various abrasive coatings and grit sizes are used for the same cylindrical holder. Disadvantages of such abrasive carriers include the difficulty of securely holding the band-shaped abrasive and the contamination of the grinding tool and drive mechanism with grinding dust.

[0005] From DE 7241264 U a combined grinding and milling tool is known for machining surfaces, in which a grinding head is attached to a drive at the front and comprises a concentrically mounted grinding and milling body.

[0006] Another grinding tool is known from DE 8322326 U1. This document deals with a rotating grinding tool with a safety guard and a dust collection device, which consists of a stationary suction hood fixed to the tool housing and connectable to a suction source, and a rotatable nozzle carried coaxially to the rotating grinding wheel by the hood. This grinding tool features an improved design of the dust collection device, which can operate in conjunction with any grinding wheel within a certain diameter. The grinding tool has a nozzle for the dust collection device in the form of a radially projecting section that extends beyond both the circumference of the grinding wheel and the circumference of the safety guard.

[0007] Such grinding tools are complex in design and unwieldy, making them difficult to handle. Furthermore, there is a growing need for portable grinding tools to achieve reproducible grinding results. Another known problem with existing grinding tools is that grinding dust contaminates and accumulates in the motor or drive unit. Such contamination can lead to malfunctions and breakdowns. This is generally unavoidable, as existing tools are operated with an external drive motor, which is always exposed to the grinding dust. External drive motors also have the disadvantage of high noise levels and require a relatively large installation space.

[0008] It is also desirable for grinding tools to have the longest possible service life in order to improve the service life of the tools and thus reduce the costs of industrial welding tasks.

[0009] Further prior art in the present technical field is disclosed in documents US 7 022 003 B1, DE 1 806 922 U, DD 11 956 A, US 4 458 453 A, US 2012 / 0115 404 A1 and US 1 723 821 A.

[0010] It is therefore an object of the present invention to overcome the aforementioned disadvantages and to provide an improved grinding tool which is compact in design, has reduced noise generation, is easy to handle and with which reproducible grinding results can be achieved.

[0011] This problem is solved with a grinding tool according to claim 1.

[0012] The basic idea of ​​the present invention is to design the grinding body of the grinding tool with a receiving space for receiving the drive unit and thus to accommodate the drive unit in the receiving space of the grinding body.

[0013] According to the invention, a grinding tool comprising a handle with a gripping surface is proposed, wherein a rotatably driven grinding element is attached to the handle. The grinding element has a receiving chamber in which a drive unit for rotating the grinding element is arranged. As a result of the rotating drive of the grinding element, the grinding dust is transported outwards away from the grinding element and thus away from the drive unit. In this way, it can be ensured that the grinding dust generated by the rotational movement of the grinding element during grinding is transported away from the drive unit.

[0014] Furthermore, such a design allows for a compact construction, which also simplifies the handling of the grinding tool.

[0015] In a preferred embodiment of the invention, the drive unit is designed as a brushless electric motor without sliding contacts (brushless motor). By eliminating the sliding contacts of the electric motor, a particularly long service life of the grinding tool can be ensured.

[0016] In an alternative embodiment of the invention, the drive unit can also be designed as a motor driven by compressed air. This also ensures a long service life for the grinding tool. Furthermore, a better power output and thus higher power density can be achieved compared to a brushed motor with relatively high power losses due to heat generation.

[0017] In a further preferred embodiment of the invention, the grinding body of the grinding tool is designed as a hollow cylindrical grinding body, inside of which the receiving space for the drive unit is arranged. By designing a cylindrical grinding body that is configured as a hollow cylindrical grinding body with a receiving space, a particularly compact design can be achieved. In a further preferred embodiment, the grinding body can also be fixed to the cylinder surface of the motor by means of a centrifugal clutch.

[0018] In a particularly preferred embodiment of the invention, the drive unit is arranged entirely within the receiving space of the grinding wheel, and the grinding wheel further comprises a cover that seals the receiving space tightly, preferably dust-tight. Such an "encapsulated" design of the grinding wheel with integrated drive unit ensures that any grinding dust generated is kept away from the drive unit particularly effectively.

[0019] According to the invention, the grinding body, in particular the previously described cylindrical grinding body, is mounted on its central axis of rotation on an arm attached to the handle. Furthermore, according to the invention, the arm is designed as a pivoting arm that can move back and forth against the spring force of a spring. This design ensures that, in the event of excessive pressure being applied to the grinding tool against a working surface, the arm will deflect in a spring-like manner and counteract the user's operating force. This spring action ensures that the grinding tool can be pressed against the working surface with a defined, preferably adjustable, spring force.

[0020] It is further preferred to design the spring force of the arm to be adjustable. In a particularly advantageous embodiment of the invention, the arm is therefore designed as a spring-loaded rocker arm with adjustable spring force. The degrees of freedom of movement of the arm are particularly preferably in a direction perpendicular to the direction of rotation of the cylindrical grinding body.

[0021] It is further advantageous to provide the grinding tool with at least one support edge and / or a bearing surface on the handle for targeted guidance of the grinding tool along a machining surface. In a simple embodiment of the invention, for example, a support edge parallel to the axis of rotation of the grinding body can be arranged on the end face of the handle, allowing the grinding tool to be moved slidably over a machining surface. If the support edge is designed as a protruding ridge, the grinding tool can therefore be held at a suitable angle around the apex of the ridge and moved along the machining surface during the grinding process.

[0022] Alternatively, the handle of the grinding tool can also be designed with a support surface that serves to guide the grinding tool along or on the machining surface in a defined manner. This ensures that the grinding tool is operated by the operator in the intended position relative to the machining surface. In a further preferred embodiment of the invention, the support surface can be designed with a plurality of ball bearings or sliding bearings to ensure the smoothest possible operation across the machining surface.

[0023] It is further advantageous if the contact surface on the handle is designed such that the grinding wheel protrudes with a section of its grinding surface segment relative to the guide plane formed by the contact edge. This provides a defined grinding plane, allowing the grinding wheel to be pressed onto the workpiece surface with a defined force from the spring arm.

[0024] It is further advantageous if the handle is designed to have integrated dust extraction. It is particularly advantageous if the handle has an opening at the end facing the grinding wheel, into which the grinding dust can be drawn, while an outlet for the extraction is provided at the other or opposite end of the handle.

[0025] Other advantageous embodiments of the invention are characterized in the dependent claims or are described in more detail below together with the description of the preferred embodiment of the invention with reference to the figures.

[0026] They show: Fig. 1 a first embodiment of a grinding tool according to the invention; Fig. 2 a second embodiment of a grinding tool according to the invention; Fig. 3 a schematic sectional view through the in Fig. 1 shown embodiment and Fig. 4 A perspective view of a grinding wheel with one arm.

[0027] With reference to Fig. 1 to Fig. 4. Identical reference symbols indicate identical features or functions. In the Fig. 1 and Fig. Figure 2 shows two exemplary embodiments of a grinding tool 20 according to the invention. The grinding tool 20 is made of Fig. 1 comprises a handle 1 with a gripping surface 2, to which an arm 8 is pivotably attached about a pivot bearing 8a. At the end 8b of the arm 8 opposite the pivot bearing 8a, a cylindrical grinding body 3 is attached to or rotatably mounted on its central axis of rotation 7. The cylindrical grinding body 3 can be driven by a drive unit 5 to rotate, preferably in any direction of rotation. The grinding body 3 is equipped with Fig. 3 A schematically indicated drive unit 5 is housed in the receiving space 4 of the grinding wheel 3. This is described in the description for Fig. 3 described in more detail later. The arm 8 is resiliently mounted on the pivot bearing 8a by means of a spring (not shown) so that it can move back and forth.

[0028] In this respect, the spring-mounted arm 8 serves as a swing arm and can move in the event of increased pressure on the grinding body 3. Fig. The spring upwards is shown in view 1.

[0029] Furthermore, the grinding tool has 20 features. Fig. 1. A support edge 11 is provided, which allows the grinding tool 20 to be guided along a machining surface 14. The support edge serves both as a defined stop with regard to the grinding depth and as a guide for the operator to guide the grinding tool.

[0030] In a further embodiment of the invention not shown, the support edge 11 can be adjustable and thus height-changeable on the handle 1, so that the machining depth can be suitably adjusted by changing the position of the support edge.

[0031] In an alternative embodiment of the invention, as described in Fig. As shown in Figure 2, the handle 1 is designed with a support surface 12 instead of a support edge 11. In this way, the grinding tool 20 can be actuated via a working surface 14, thus enabling precise guidance of the grinding tool. The grinding tool 20 otherwise has the same features as in the first embodiment. Fig. The further features described in section 1 include a spring-loaded arm 8 (swing arm) and a handle 1 with a gripping surface 2. Both embodiments of the grinding tools 20 are each equipped with a dust extraction system 15 integrated into the handle 1.

[0032] In Fig. Figure 3 is a schematic sectional view through the grinding tool 20. Fig. Figure 1 shows the handle 1 being hollow inside and providing a channel for the dust extraction 15. The inlet opening 17 serves to allow the entry of grinding dust, which flows along the direction of the arrow into Fig. 3 can be conveyed in the direction of the outlet of the extraction system 15. The previously described arm 8 is also attached to the handle 1 so that it can be moved back and forth. At the Fig. At the lower end of the arm 8, the grinding body 3 is rotatably mounted on its central axis of rotation 7. A drive unit 5 is shown in the receiving chamber 4 of the grinding body 3. In the present embodiment, the drive unit 5 is shown by way of example as a brushless electric motor without sliding contacts. The grinding body 3 comprises a bell 16 in which the stator 18 of the electric motor is arranged. The cylindrical outer wall of the grinding body 3 is provided with an abrasive grain 19. As shown in Fig. As shown in Figure 4, the cylindrical grinding body 3 has an electrical connection 21 that runs along the arm 8. Advantageously, this connection is a three-phase motor connector. ... Fig. As can also be seen in Figure 3, the grinding element 3, which is rotatably mounted on the pivot bearing 7 of the arm 8, is provided with a cover 6. The cover 6 serves to seal the receiving chamber 4 dust-tight and thus to protect the drive unit 5.

[0033] Instead of the brushless electric motor, a pneumatically or compressed air-driven motor can also be integrated into the receiving chamber 4 of the grinding wheel 3. In that respect, the one in Fig. 4 to replace the electrical connection 21 shown by a pneumatic line or compressed air line, which is suitablely connected to the compressed air-operated motor.

[0034] The invention is not limited in its implementation to the preferred embodiments specified above; rather, a number of variants are conceivable which make use of the solution shown, even in a fundamentally different design.

Claims

[1] Grinding tool comprising a handle (1) with a gripping surface (2), wherein a rotatable grinding body (3) is attached to the handle (1), the grinding body having a receiving space (4) in which a drive unit (5) for rotating the grinding body (3) is arranged, wherein the grinding body (3) is mounted on its central axis of rotation (7) on an arm (8) attached to the handle (1), characterized by , that the arm (8) is designed as a swing arm which can be moved back and forth against a spring force of a spring on the pivot bearing (8a). [2] Grinding tool according to claim 1, characterized by , that the drive unit (5) is a brushless electric motor without sliding contacts. [3] Grinding tool according to claim 1, characterized by , that the drive unit (5) is a motor that can be driven by compressed air. [4] Grinding tool according to any one of claims 1 to 3, characterized by, that the grinding body (3) is a hollow cylindrical grinding body, inside of which the receiving space (4) for the drive unit (5) is arranged. [5] Grinding tool according to claim 4, characterized by , that the receiving chamber (4) of the grinding body (3) fully accommodates the drive unit and a cover (6) is provided which seals the receiving chamber (4) in a dust-tight manner. [6] Grinding tool according to one of the preceding claims, characterized by that the handle (1) has at least one support edge (11) and / or a support surface (12) for the targeted guidance of the grinding tool (10) along a machining surface (14). [7] Grinding tool according to claim 6, characterized by , that the support surface (12) on the handle (1) is provided such that the grinding body (3) protrudes with a grinding surface segment section (13) relative to one of the guide planes formed by the support surface (12). [8] Grinding tool according to one of the preceding claims, characterized by , that the handle (1) further includes a suction port (15).

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