Device for automatic and safe tensioning of a sanding belt with force limitation and controlled release

Abstract

Device for tensioning an abrasive belt (10), comprising a tensioning roller (2) movably mounted on a pivot arm (3) which is pre-tensioned by an elastic element (4) arranged between a frame (5) and said pivot arm (3) to exert a tensioning force on the abrasive belt (10), characterized in that the pivot arm (3) is designed to pivot under the influence of a force exerted on the abrasive belt (10), which causes a displacement of the tensioning roller (2) and an automatic reduction of the belt tension in order to limit the force exerted by the abrasive belt (10) to a value of at most 100 N.

Description

[0001] The present invention relates to a clamping device for a grinding belt intended for finishing, polishing, satin finishing or grinding machines, particularly in the field of watchmaking, polishing technology and micromechanics.

[0002] Common belt grinding machines generally incorporate rigid or highly pre-tensioned tensioning systems. These systems have significant disadvantages, including inconsistent tension, a lack of response when an object enters the belt path, considerable risks of entrapment or injury, vibrations, running irregularities, and difficult belt changes requiring significant force.

[0003] In certain precision applications, particularly in watchmaking and fine polishing, operators must have direct access to the wheels and surrounding area of ​​the grinding belt. Conventional guards can create additional risks or may be removed by users to gain access to the work areas, significantly increasing the hazards associated with their use.

[0004] The invention aims to provide a device capable of ensuring substantially constant belt tension, improving safety by limiting pinching forces, enabling automatic release in the event of intrusion, improving belt guidance, and facilitating belt replacement.

[0005] In certain embodiments: The invention relates to a device comprising a drive roller and a tension roller movably mounted on a pivot arm. The pivot arm is pre-tensioned by an elastic element arranged between a fixed frame and said arm to exert a tension force on the grinding belt. - According to the invention, the swivel arm is designed in such a way that it pivots under the influence of an external force exerted on the grinding belt, which leads to a displacement of the tension roller and an automatic reduction of the belt tension. - The device is designed to limit the force exerted by the abrasive belt to a maximum value of 100 N in order to keep the contact pressure below a biomechanical safety threshold if a finger or object gets into the path of the abrasive belt. The tension roller is attached to a T-shaped swivel part, which is mounted in an adjustable bracket attached to the swivel arm. The device further includes an adjustment system that allows the tension roller to be positioned in several detent positions, achieved by means of a symmetrical detent system in conjunction with an adjusting screw. - The swivel arm is equipped with low-friction elements, such as a sliding bearing and, in particular, sliding discs, which allow for rapid movement of the system when an object is inserted, thus aiding in the release of tension. - The tension roller has a smooth, protruding geometry and incorporates internal rotating elements inaccessible to the user to eliminate any potential snagging points. The roller's geometry also allows for self-centering of the sanding belt.

[0006] The accompanying drawings illustrate the invention: Fig. shows an isometric view of the device. Fig. Figure 2 shows a side view of the clamping system in the operating position.

[0007] With reference to these drawings, the device comprises a drive roller mounted on the machine shaft (1), a tension roller (2), a pivot arm (3), an elastic element (4) arranged between a frame (5) and the pivot arm (3), a pivoting part (6) supporting the tension roller (2), an adjustable bracket (7), and a positioning system comprising an indexing system (8) and a positioning screw (9). When an external force is applied to the abrasive belt (10), the pivot arm (3) pivots, causing the tension roller (2) to move and the belt tension to decrease, thus preventing any dangerous force.

[0008] According to one variant not shown, the elastic element can consist of any equivalent means capable of exerting a tensile force and enabling an automatic reduction of this tension under external load, regardless of their type or technology.

[0009] The device is particularly suitable for machines that require direct access to the grinding belt for contouring work, edge processing and precision polishing processes.

Claims

[1] Device for tensioning a sanding belt (10), comprising a tensioning roller (2) movably mounted on a pivot arm (3) which is pre-tensioned by an elastic element (4) arranged between a frame (5) and said pivot arm (3) to exert a tension force on the sanding belt (10), characterized by , that the pivoting arm (3) is designed to pivot under the influence of a force exerted on the abrasive belt (10), which causes a displacement of the tensioning roller (2) and an automatic reduction of the belt tension in order to limit the force exerted by the abrasive belt (10) to a value of no more than 100 N. [2] Device according to claim 1, wherein the pivot arm (3) is attached to the frame via elements with a low coefficient of friction, in particular sliding bearings. [3] Device according to claim 1, wherein the tension roller (2) is attached to a pivoting part (6). [4] Device according to claim 1, wherein the pivoting part (6) is mounted on an adjustable bracket (7) which is attached to the pivoting arm (3). [5] Device according to claim 1, comprising an adjustment system which enables the positioning of the tension roller (2) in several detent positions by means of a detent system (8) which is connected to an adjusting screw (9). [6] Device according to claim 1, wherein the tension roller (2) has a smooth geometry without protrusions and includes internal rotating elements inaccessible to the user in order to eliminate any snagging points. [7] Device according to claim 1, wherein the geometry of the tension roller (2) is designed to ensure self-centering of the abrasive belt.

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