Device for angle-guided grinding of blades

Abstract

A device for angle-guided grinding of blades, comprising a blade holder (14) mounted in such a way as to ensure a fixed grinding angle or angular range, attached to a guide rod (7) which is attached to a base (for example, a column (3)) in such a way that it is movable parallel and normal to the base plate (1), but cannot be tilted, characterized in that this mounting consists of only one arm rotatably mounted normal to the working surface, wherein the guide rod (7) is linearly mounted along the longitudinal axis of the arm (18) and can be moved.

Description

[0001] When grinding blades, especially knives, a constant angle is very important, as the grinding angle significantly influences the blade's properties. When grinding by hand on bench stones, it is almost impossible to maintain a constant angle. Therefore, a number of devices have been designed that allow a constant angle to be maintained. However, these are limited in terms of the usable abrasives or cause small systematic angle errors. Such systems are described, for example, in US8303381 B2 or US6846229B1.

[0002] A significant development in this regard are systems in which a bench stone can still be used, similar to freehand sharpening, but the blade is clamped by the system in such a way that it can be guided freely over the grindstone, but the angle to the abrasive is fixed. One such system is described in AT523721 B1. These systems typically comprise a column attached to the work surface, on which the abrasive is placed parallel to its surface. An arm is attached to this column, which is mounted parallel to the work surface and can rotate about the column. At the end of the first arm, a second arm is attached, mounted in the same way. A guide rod is attached to the second arm, normal to the work surface. This guide rod can move perpendicular to the surface and can also rotate about its longitudinal axis. The connection between the rod and the arm is typically achieved via a linear ball bearing.The guide rod can therefore be moved normal to the work surface and, by rotating both arms, also parallel to the work surface, but tilting is not possible.

[0003] A blade holder is mounted on the underside of the guide rod. It consists of two elements. Firstly, an element which is firmly connected to the guide rod and sets the sharpening angle. This can usually be adjusted by the user. The blade is attached to the second element. This is typically achieved using magnets or a clamping device. The second element is rotatably mounted to the first. The axis of rotation is at the sharpening angle to the guide rod and perpendicular to the blade surface. By combining the axes of rotation through the longitudinal axis of the guide rod perpendicular to the grinding medium and the second axis of rotation, which rotates around the sharpening angle to it, even curved cutting edges can be ground at a constant angle. The two arms attached to the column ensure that the guide rod remains perpendicular to the grinding medium, but can otherwise be moved freely.

[0004] While such systems can achieve very good results and allow for the flexible use of different grinding media, the two rotating arms result in some undesirable properties.

[0005] First of all, the systems require a lot of working and storage space due to the two arms. Furthermore, some orientations of the two arms require more force to achieve the desired blade movement. This is because the torque in the arm bearings, which results from the force acting on the blade, depends on the relative orientation of the arms. This variable torque is noticeable to the user during operation and makes the grinding movement unbalanced.

[0006] To reduce this effect, the arms are typically made longer than technically necessary for standard blade lengths. Furthermore, the grinding media is positioned farther from the base than geometrically required, as a smaller angle between the arms would reduce this effect. However, both of these measures further increase the required working space.

[0007] The long arms with two pivot bearings also pose a mechanical problem: To achieve the system's rigidity required for high angular precision, both the bearings and the arms themselves must be constructed with correspondingly large dimensions. This not only increases manufacturing costs but also the mass moved within the system.

[0008] The object of the invention is therefore to design a system for the hand-guided grinding of blades which avoids the problems described in existing systems based on two rotating arms. For this purpose, a guide rod perpendicular to the grinding medium with a blade holder is used, which enables a fixed grinding angle (range) even with curved blade geometries. The bearing of the guide rod, which enables movements parallel to the work surface but must prevent tilting, is no longer solved with two rotating arms. Instead, only a single arm is used, which is mounted on the base so that it can rotate about an axis perpendicular to the work surface. A linear bearing parallel to the longitudinal axis of the arm ensures that the guide rod can move freely parallel to the work surface.

[0009] The work surface can be part of the device, but it's also conceivable for the device to be secured to a table, for example, with a clamp. Bench stones are typically used as the abrasives. However, the use of a wide variety of abrasives is generally conceivable. The device can also be used in combination with a grinding machine, such as a rotating stone or a sanding belt.

[0010] This modified kinematics has many advantages. First, only one arm is required, making the device much more compact. The length of the single arm can be selected based on the expected blade shapes. Additional length to avoid stiff positions is unnecessary. Due to the shorter arm length and the elimination of the pivot bearing, it is much easier to achieve the rigidity required for high angular accuracy. This allows the arm to be designed much lighter, further increasing user-friendliness. Fiber composite materials, for example, can be used for this purpose.

[0011] However, to make such a system based on an arm and a linear bearing simple and convenient to use, a linear guide is required that is extremely smooth and quiet, yet free of play. A number of possible solutions are conceivable for this, including linear ball bearings and bearing bushes. Adjustable roller guides, however, offer particularly advantageous properties. They run extremely quietly and can be adjusted to be free of play, yet still smooth. Furthermore, the requirements for the bearing guideway in terms of hardness and surface quality are significantly lower than for other bearing types. This allows the use of fiber composite materials for the guideways.

[0012] To further save weight, it makes sense to use the guide rails as the load-bearing element of the arm. While it would be possible to implement the arm as a structural element on which the guide rails are mounted, this would automatically result in additional moving dimensions.

[0013] This results in two possible arrangements for the linear bearing. Firstly, the rails (or rail) can be permanently connected to the linear ball bearing of the guide rod. The rollers or bearing bushings are mounted on the base so they can rotate. They therefore move with every movement of the linear bearing. This configuration generates high bearing forces and significantly increases the required installation space. However, it has the advantage that the arm is not in the user's field of vision. The second option is to attach the guide rod to the rollers or bearing bushings. The rails are mounted on the base so they can rotate. Accordingly, they do not need to move with linear movements, which reduces the moved dimensions. Furthermore, the bearing forces are significantly lower and only about half the installation space is required. In general, the second configuration is preferable for the device.

[0014] A possible implementation for such a device is in the Fig. 1-3 shown. Fig. 1: Overview of the device Fig. 2: Detailed view of the roller guide Fig. 3: Detailed view of the angle adjustment and blade holder

[0015] The device is based on a column (3) attached to a base plate (1) on which the abrasive (2) is placed. The holder (4) for the linear rails (6) is rotatably mounted at the upper end of the column via axial bearings. The linear rails (6) are designed as rods with a round cross-section. The rotation axis (5) of the arm, which is formed by the linear rails, the holder (4), and the end cap (12), thus runs perpendicular to the work surface through the column (3).

[0016] The bearing block (11) can be moved along the longitudinal axis of the arm (18). This bearing block serves as a holder for the 8 bearing rollers (20) and associated shafts (26) and a linear ball bearing (21), which only allows the guide rod (7) to move along its own longitudinal axis (16) and rotates around it. The distance between the bearing rollers can be adjusted using the four adjusting screws (22) so that the bearing is free of play and yet runs smoothly and wear can be compensated for. To make this possible, the bearing block consists of two individual parts (23 & 25). The adjusting screws also serve as shafts for the guide rollers (24), which ensure that there is no contact between the bearing block (11) and the guide rails (6).

[0017] The angle adjustment (13) is mounted at the bottom of the guide rod (7). This consists of a fixed element (28) and a rotating element (27). By turning a knurled screw (30), the grinding angle can be adjusted by rotation around a pin (31). The mechanism is pre-tensioned by tension springs (29) to prevent angular deviations. The magnetic blade holder (14) is mounted to rotate about an axis that is at the grinding angle to the guide rod (7). A compression spring (9) serves to relieve the weight during the grinding process; its force is transmitted to the guide rod (7) via an adjustable adjusting ring (8). QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 8303381 B2

[0001] US 6846229B1

[0001] AT 523721 B1

[0002]

Claims

[1] A device for angle-guided grinding of blades, consisting of a blade holder (14), mounted in such a way that it ensures a fixed grinding angle or angular range, fastened to a guide rod (7) which is fastened to a base (for example a column (3)) in such a way that it is movable parallel and normal to the base plate (1), but cannot be tilted characterized by that this bearing consists of only one arm which is mounted in a rotational manner normal to the work surface, whereby the guide rod (7) is mounted linearly along the longitudinal axis of the arm (18) and can be moved. [2] A device according to claim 1, characterized by that the linear guide of the guide rod (7) in the longitudinal axis of the arm (18) is designed as a roller guide. [3] A device according to claim 1, characterized by that the arm is formed by the guide rail or rails (6) of the linear bearing along the longitudinal axis of the arm. [4] A device according to claims 1 & 2, characterized by that the roller guide can be adjusted using adjusting screws (22). [5] A device according to claim 1, characterized by that the arm is made of a fiber composite material.

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