Grinding machine

Grinding machine (1), comprising:

• a grinding tool (2, 3, 10) having at least one grinding surface (11, 11a, 11b);
• at least one electrode (60, 60a, 60b), which is positioned in the vicinity of at least a portion of the grinding surface (11, 11a, 11b), such that a dressing area (75, 75a, 75b) is obtained in which a relatively small gap is present between the electrode (60, 60a, 60b) and the grinding surface (11, 11a, 11b);
• feed means (70) for feeding electrolyte to the dressing area (75, 75a, 75b);
• and
• a generator (20) for generating an electric current between the grinding surface (11, 11a, 11b) and the electrode (60, 60a, 60b), via the electrolyte;
• wherein the electrode (60, 60a, 60b) is provided with holes (62), and wherein one side of at least a portion of the holes (62) ends up in the dressing area (75, 75a, 75b).

Process for dressing at least two grinding surfaces (11a, 11b) of one grinding tool (2) simultaneously, comprising the following steps:

• assigning at least a portion of an electrode (60a, 60b) to at least a portion of each grinding surface (11a, 11b);
• positioning the electrodes (60a, 60b) in the vicinity of the respective grinding surfaces (11a, 11b), such that dressing areas (75a, 75b) are obtained in which a relatively small gap is present between the electrodes (60a, 60b) and the respective grinding surfaces (11a, 11b);
• feeding electrolyte to the dressing areas (75a, 75b);
• and
• bringing about an electric current between the grinding surfaces (11a, 11b) and the electrodes (60a, 60b), via the electrolyte.

Method for controlling the z-position of a slide (30) for supporting and positioning a workpiece (40), wherein the slide (30) is supported on a supporting surface (35) of a fixed base (36) through bearing means (31) and actuators (32) having an adjustable length, comprising the following steps:

• a) determining a relation between a distance (D) between the supporting surface (35) and a flat virtual reference plane (51) on the one hand and possible combinations of x-positions and y-positions of the bearing means (31) on the supporting surface (35) on the other hand;
• b) determining an actual x-position and y-position of the bearing means (31) on the supporting surface (35);
• c) finding the actual distance (D) between the supporting surface (35) and the virtual reference plane (51) on the basis of the actual x-position and y-position of the bearing means (31) on the supporting surface (35) and the relation as determined during step a);
• and
• d) determining the required length (L) of the actuators (32) on the basis of a known required distance (C) between the slide (30) and the virtual reference plane (51), a known length (B) of the bearing means (31), and the actual distance (D) between the supporting surface (35) and the virtual reference plane (51) as found during step c).

Method for controlling the z-position of a slide (30) for supporting and positioning a workpiece (40), wherein the slide (30) is supported on a supporting surface (35) of a fixed base (36) through bearing means (31) and actuators (32) having an adjustable length, comprising the following steps:

• a) determining a relation between a distance (D) between the supporting surface (35) and a flat virtual reference plane (51) on the one hand and possible combinations of x-positions and y-positions of the bearing means (31) on the supporting surface (35) on the other hand;
• b) determining a relation between a distance (R) between the supporting surface (35) and an actual reference plane (52) on the one hand and possible combinations of x-positions and y-positions of the bearing means (31) on the supporting surface (35) on the other hand;
• c) determining an actual x-position and y-position of the bearing means (31) on the supporting surface (35);
• d) determining an actual distance (S) between the slide (30) and the actual reference plane (52);
• e) finding the actual distance (D) between the supporting surface (35) and the virtual reference plane (51) on the basis of the actual x-position and y-position of the bearing means (31) on the supporting surface (35) and the relation as determined during step a);
• f) finding the actual distance (R) between the supporting surface (35) and the actual reference plane (52) on the basis of the actual x-position and y-position of the bearing means (31) on the supporting surface (35) and the relation as determined during step b);
• g) determining the required distance (S) between the slide (30) and the actual reference plane (52) on the basis of a known required distance (C) between the slide (30) and the virtual reference plane (51), the actual distance (D) between the supporting surface (35) and the virtual reference plane (51) as found during step e) and the actual distance (R) between the supporting surface (35) and the actual reference plane (52) as found during step f);
• h) comparing the required distance (S) between the slide (30) and the actual reference plane (52) as determined during step g) to the actual distance (S) between the slide (30) and the actual reference plane (52) as determined during step d);
• and
• i) adjusting the z-position of the slide (30) such that the actual distance (S) between the slide (30) and the actual reference plane (52) as determined during step d) equals the required distance (S) between the slide (30) and the actual reference plane (52) as determined during step g).

Method for controlling the z-position of a slide (30) for supporting and positioning a workpiece (40) which is subjected to a cutting treatment being performed by a cutting tool, comprising the following steps:

• a) determining a position setpoint for the position of the slide (30) on the basis of a required depth of cut;
• b) determining the value of a cutting force (F) acting on the slide (30);
• c) comparing the value of the cutting force (F) to a value of a force limit;
• d) adjusting the z-position of the slide (30) in such a way that the actual z-position of the slide (30) is further away from the cutting tool than the position setpoint, in case the value of the cutting force (F) is larger than the value of the force limit.