GB2132520A

GB2132520A - Grinding machine

Info

Publication number: GB2132520A
Application number: GB08325750A
Authority: GB
Inventors: Ludwig Mullner
Original assignee: Friedr Dick GmbH and Co KG
Current assignee: Friedr Dick GmbH and Co KG
Priority date: 1982-12-09
Filing date: 1983-09-27
Publication date: 1984-07-11
Also published as: IT8323618A0; FR2537487A1; IT1194452B; DK565483D0; DE8234524U1; JPS59187444A; GB2132520B; GB8325750D0; DK565483A

Abstract

A Grinding machine comprises a grinding wheel (1) and a guide element (6,7) which can be brought into abutment with the wheel to guide a blade of a knife or other workpiece against the wheel, the guide element (6) being inclined to the axis of the wheel and comprising, at least in part, a permanent magnet (7). The magnet serves to retain the blade at a correct angle to the wheel. <IMAGE>

Description

SPECIFICATION Grinding machine The invention relates to a grinding machine with a drivable grinding wheel and with a guide element which can be brought into abutting contact with the grinding wheel and serves for grinding a blade-shaped part of a cutting tool, more especially a knife, and whose guide surface is arranged at the front end of the grinding wheel so as to be inclined towards the axis thereof.

On a known grinding machine of the aforementioned kind the guiding element is designed so as to be plate-shaped and is arranged directly above the shaft of the grinding wheel. The guiding element is fitted to a rocking lever which can be set by means of an adjusting screw (DE GM 71 45 272).

It is also known to mount the guide element itself pivotally and to render it adjustable by means of an adjusting screw (DE OS 25 43 718).

The task underlying the present application is to provide a reliable guide for the tool to be ground, more especially a knife. According to the invention, a grinding machine with a drivable grinding wheel and with a guide eiament which can be brought into abutting contact with the grinding wheel and serves for guiding a bladeshaped part of a cutting tool, more especially a knife, and whose guide surface that is directed towards the grinding wheel is arranged at the front end of the grinding wheel and so as to be inclined towards the axis thereof, wherein the guide surface is at least partly the side surface of a permanent magnet which is fastened in the guide element.The force exerted by the permanent magnet on the blade-shaped part of the tool to be ground seeks to retain this part on the guide surface, thus bringing about a reliable guidance of the tool in a predetermined position. When the blade-shaped part to be ground is in abutting contact with the guide surface, the desired cross section of the cutting edge is attained.

From DE GM 74 40 484 there is known a grinding machine in whose contact surface a permanent magnet has been embedded in such a way that its base surface is flush with the locating surface. The locating surface extends parallel to the axis of the grinding wheel. The arrangement of a permanent magnet in the afore-described locating surface has not proved to be successful in practice.

The invention is further described by means of example with reference to the drawings, of which: Figure 1 shows a front view, Figure 2 shows a top view, Figure 3 shows a section along the line Ill-Ill in Figure 2, and Figure 4 shows a partial lateral view.

A grinding wheel 1, which tapers outwardly on its face, is provided on its two sides with conical surfaces 2 and 2a respectively. It is fitted on a shaft 3, which is drivable by means of a motor not shown, so as to be secured against rotation. The shaft 3 is rotatably mounted in laterally arranged bearings 4 and 4a which are fastened to a housing 5, whose design is rectangular in a top view and U-shaped in a perpendicular section.

With the conical surface 2 there is associated a guide surface 6 which is provided on a discshaped permanent magnet 7 (Figure 3). The permanent magnet 7 is fastened in a cup-shaped reception body 8, whose edges extend to the guide surface 6. The reception body 8 is fastened with the aid of a pin 9, which is centrically fitted thereto, to a threaded spindle 10 which is adjustably mounted in a retaining body 11 fastened on the housing 5. For securing the threaded spindle 10 in position, there serves a lock nut 13 which is provided with a handle 12 and is designed as a domed nut and which is arranged on the side of the retaining body 1 1 that is directed away from the permanent magnet 7.

The point 14, nearest to the grinding wheel 1, of the reception body 8 or of the permanent magnet 7 if the reception body 8 does not extend to the guide surface 6, is at such a distance from the grinding wheel 1 that this wheel does not strike against the point 14 during operation. The tangent plane on the grinding wheel 1 at the point of the grinding wheel 1 which is adjacent to the point 14 of the reception body 8 and the planes determined by the guide surface 6 are intersected in a generatrix of the conical surface 2 which intersects the axis of the grinding wheel 1.

Considered in the direction of this generatrix, the two planes form an angle P of 100 to 300, more especially 200 (Figure 3). Considered in the direction of the arrow A in Figure 3, which arrow indicates the direction of rotation of the grinding wheel 1, the point 14 is at an angle a of 250 to 450, more especially 350, to the horizontal (Figure 4, in which only the grinding wheel 1 is shown and the guide surface 6 is dash-dotted).

As Figures 1 and 2 show, there is also associated with the conical surface 2a a guide surface 6a of a magnet which is located in a reception body 8a. The above explanations made in connection with the guide surface 6 apply thereto correspondingly.

For grinding a knife, it is placed, with the cutting end that is adjacent to its handle, into the hollow wedge between the conical surface 2 of the grinding wheel 1 and the guide surface 6 of the permanent magnet 7, the blade coming into abutting contact with the permanent magnet 7.

The cutting edge of the knife is ground by a pulling movement away from the grinding wheel 1. If the cutting edge has a curved end, then the knife handle is moved slightly upwards at the end of the grinding operation. The metal removal during the grinding operation is determined by the force with which the blade of the knife is pressed downwards during the grinding operation. In order to ensure that a cutting phase of equal width is brought about on either side of the knife edge, the knife blade is also ground on the conical surface 2a of the grinding wheel 1 in the afore-described manner, the blade coming into abutting contact with the guide surface 6a.

The blade of the knife to be ground is reliably guided during the grinding operation along the guide surface 6 of the permanent magnet 7 and on the guide surface 6a of the permanent magnet 7a and assumes a clear position relative to the grinding wheel 1, so that the blade of a knife can be ground in a simple manner even by an unskilled person. An accurate edge geometry is observed due to the abutting contact of the blade to be ground with the guide surfaces 6 and 6a.

If after various grinding operations the point 14 is too far away from the grinding wheel 1, the guide surfaces 6 and 6a may be readjusted. A readjustment thereof is also possible when a tool provided with a blade other than a knife is ground.

Claims

1. A grinding machine with a drivable grinding wheel and with a guide element which can be brought into abutting contact with the grinding wheel and serves for guiding a blade-shaped part of a cutting tool, more especially a knife, and whose guide surface that is directed towards the grinding wheel is arranged at the front end of the grinding wheel and so as to be inclined towards the axis thereof, wherein the guide surface is at least partly the side surface of a permanent magnet which is fastened in the guide element.

2. A grinding machine as claimed in Claim 1, wherein the point of the guide surface that is nearest to the grinding wheel lies in a radial to the axis of the grinding wheel which is arranged at an angle (a) of 250 to 450, more especially 350, to the horizontal and above the shaft of the grinding wheel in a zone of this grinding wheel which moves from the bottom to the top.

3. A grinding machine as claimed in Claim 2, wherein the said angle (a) is 350.

4. A grinding machine as claimed in Claim 1 or 2, wherein the line of intersection of the planes which are determined by the guide surface and by the tangent plane on the part, nearest to the guide surface, of the conical surface of the grinding wheel lies on a generatrix which intersects the axis of the grinding wheel, and in that, considered in the direction of this generatrix, the angle (,3) which is open towards the top, between the guide surface and this tangential surface is 100 to 300.

5. A grinding machine as claimed in Claim 4, wherein the said angle (,B) is 200.

6. A grinding machine as claimed in one of the preceding Claims, wherein the permanent magnet is disc-shaped and is fastened in its cup-shaped reception body, whose edge embraces the permanent magnet on its circumference and extends to the guide surface.

7. A grinding machine as claimed in one of the preceding Claims, wherein the guide element is arranged on an end of a threaded spindle which is adjustably mounted in a retaining body arranged on a housing.

8. A grinding machine substantially as hereinbefore described with reference to the accompanying drawings.