Patent Grant
11980994
The invention relates to a support plate for rotating flexible tools for surface machining such as grinding or polishing. The support plate is provided at the bottom side with a circumferentially extending circular contact surface for the tool and with a fixation device provided for detachably fixing the tool at the contact surface. At the top side, the support plate comprises an axially oriented drive connector for frictional connection of the support plate to a drive.
Such a support plate is disclosed, for example, in DE 20 2006 017 622 U1. As flexible tools for surface fine machining, circular grinding disks or polishing disks are employed here. The grinding disks or polishing disks wear during normal operation but the support plate does not. In this context, a tool that is no part of the support plate and that is in the form of a grinding or polishing disk is detachably arranged at the support plate; the support plate together with the tool is subsequently connected with frictional connection via the drive connector to a hand drill or a hand grinder as rotating drives for rotating the support plate.
The invention has the object to configure a support plate of the aforementioned kind so as to be safer in regard to handling.
In accordance with the invention, this is achieved by a support plate of the aforementioned kind that is provided additionally with one or a plurality of fatigue markings that are provided on or in the top side of the support plate. Further advantageous embodiments are disclosed in the dependent claims.
The support plate serves to support the flexible tools from their back side so that during grinding or polishing with these tools a sufficient pressure can be applied onto the surface to be machined. The grinding or polishing disks which are provided as flexible tools are usually consumed in this context and, after they are spent, are replaced by new grinding or polishing disks. The support plate itself in normal use has no contact with the surface to be machined and therefore is not consumed. However, it has been found in practice that signs of fatigue in the form of small material chippings or small fissures may occur over time in the rim region of the support plate. Should they project too far in the direction toward the axis of rotation of the support plate, there is an increased risk of injury in operation of the support plate for the person working with the support plate. Also, with increasing signs of fatigue of the support plate, there is the risk in regard to the surface to be machined that the grinding or polishing process is no longer performed properly. By means of one or a plurality of fatigue markings which are applied in accordance with the invention on or in the top side of the support plate, the person that is operating the support plate can recognize whether the signs of fatigue of the support plate already have propagated so far in the direction toward the axis of rotation of the support plate that the support plate must be exchanged. The risk of injury for the person operating the support plate and also the risk of improper machining of a surface with the flexible tools is thus reduced.
Advantageously, the fatigue markings are provided in and/or on the top side of the support plate in the form of recesses and/or in the form of elevations so that they can be felt by an operator by touch. In this way, the fatigue markings can be identified by a person operating the support plate even when a purely visual identification means cannot be recognized anymore due to grinding dust that has collected on the top side of the support plate. The safety regarding safe handling of the support plate can thus be further increased.
In a particularly preferred embodiment of the invention, the totality of the fatigue markings has a center of gravity which is positioned on the axis of rotation of the support plate. In case of fatigue markings in the form of elevations, the center of gravity of the material that has been additionally applied to the top side of the support plate is located on the axis of rotation of the support plate. In case of recesses that are introduced into the top side of the support plate, the totality of these recesses has a fictional center of gravity in the form of the saved material and this fictional center of gravity is lying on the axis of rotation of the support plate. The fictional center of gravity is viewed as a center of gravity in the meaning of the invention. Also, combinations of elevations and recesses are possible. Due to the aforementioned configuration, no imbalance in the support plate is present due to the fatigue markings. The support plate itself advantageously has also a center of gravity which is located on the axis of rotation of the support plate.
In a particularly preferred embodiment of the invention, the fatigue markings, when viewing the support plate from above, are located within a circular ring whose outer radius corresponds to the radius of the support plate and whose inner radius is smaller by 10%, in particular by 8%, than the outer radius. In a particularly preferred embodiment of the invention, the inner radius of the circular ring is smaller by 5% or less than the outer radius in case that the diameter of the support plate is greater than 140 mm. Advantageously, in this context, at least the minimal distance of the fatigue marking from the axis of rotation corresponds to the inner radius, i.e., at least one of the fatigue markings coincides with the inner circle of the circular ring or that point of one of the fatigue markings that has the smallest distance from the axis of rotation of the support plate is positioned on the inner circle of the circular ring. Surprisingly, it has been found that signs of fatigue of the support plate in the form of hairline cracks or material chippings that do not extend all the way to the inner circle of the circular ring with precisely these dimensions do not impair a safe operation of the support plate but fatigue markings that project past this circular ring in the direction toward the axis of rotation of the support plate do.
The support plate according to the invention is preferably free of tools for grinding or polishing that are non-detachably (fixedly) connected thereto. A normal wear or predetermined consumption of the support plate thus does not occur.
The fixation device is preferably a clamping plate or a clamping nut wherein the tool can be clamped between the fixation device and the support plate for detachable fixation. Alternatively or as a supplement, the fixation device is a sticky coating, for example, a hook-and-loop fastener covering that interacts with a correspondingly adapted back side of the flexible tool, preferably in the form of a grinding or polishing disk.
Further advantageous embodiments of the invention can be taken from the dependent claims as well as from the schematic embodiments described in the following.
In the following, elements of the invention that are acting in the same way are provided with the same reference character, should this be expedient. The features of the invention disclosed in the following, each individually or in any combination with each other, can be subject matter of the invention.
At the bottom side, the plate body 2a of the support plates 2 comprise a fixation device 10 that is provided for detachable fixation of the tool 4 at the contact surface 8. In the embodiment according to
The support plates 2 are provided at their top side 12 with an axially oriented drive connector 14 for frictional connection of the respective support plate 2 with a drive. The drive is not illustrated in the Figures and is not part of the invention. In the embodiments, a plurality of fatigue markings 16 are provided on or in the top side 12 of the support plate 2, respectively. The totality of the fatigue markings 16 has a center of gravity 18 that is located on the axis of rotation 20 of the respective support plate 2.
The fatigue markings 16 in a view from above onto the respective support plate 2, as in the perspective views according to
The specification incorporates by reference the entire disclosure of German priority document 20 2020 103 506.1 having a filing date of Jun. 18, 2020.
While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.
| Number | Date | Country | Kind |
|---|---|---|---|
| 20 2020 103 506.1 | Jun 2020 | DE | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6250295 | Chanton et al. | Jun 2001 | B1 |
| 20030040260 | Andres | Feb 2003 | A1 |
| 20050058518 | Valentini | Mar 2005 | A1 |
| 20150148937 | Wolf | May 2015 | A1 |
| 20160158920 | Valentini | Jun 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| 20 2006 017 622 | May 2008 | DE |
| Number | Date | Country | |
|---|---|---|---|
| 20210394337 A1 | Dec 2021 | US |
