Grinding control methods and apparatus

In the known process of grinding workpieces by bringing the face of a rotating grinding wheel into relative rubbing contact with the workpiece surface, and wherein the wheel face tends to deteriorate from the desired shape therefor,

• the method of truing the wheel to restore its face to the desired shape, including
• (a) bringing the face of the grinding wheel into relative rubbing contact with the operative surface of a truing element, said surface conforming to the desired shape of the wheel face, and
• said method being characterized by
• (1) sensing at least approximately the specific truing energy ratio with which material is removed from the wheel,
• (2) selecting a predetermined specific truing energy set point value, and
• (3) adjusting at least one of (a) the relative surface speed and (b) the relative infeed rate of the wheel face and truing surface to restore the sensed ratio at least approximately to said set point value whenever the sensed ratio tends to depart substantially from such set point.

The method of conditioning the face of a grinding wheel to a desired state of sharpness, said method comprising

• rotating the wheel and feeding the wheel face into relative rubbing contact with the operative surface of a truing element, said surface conforming to the desired shape for the wheel face, and
• said method being characterized by and including
• (a) controlling the relative motions of said wheel and element to maintain the specific truing energy ratio PWR/W' at least approximately in agreement with a predetermined set point value,
• where PWR is the energy expended per unit time in creating said relative rubbing contact and W' is the volume of material removed from the wheel per unit time, and
• (b) adjusting said set point value upwardly or downwardly to make the wheel face have a desired lesser or greater degree of sharpness.

In a grinding machine, apparatus for restoring or maintaining the face of a grinding wheel in a desired shape or sharpness, said apparatus comprising in combination,

• (a) means for supporting said wheel for rotation about its axis,
• (b) means for rotationally driving the wheel,
• (c) a truing element having an operative surface conforming to the desired shape for the wheel face,
• (d) means for relatively infeeding said wheel and element to bring said face and operative surface into relative rubbing contact, and
• (e) means for contolling said infeeding and the relative surface speed of said rubbing contact to make the specific truing energy ratio fall within a preselected range.

In a grinding machine, apparatus for restoring or maintaining the face of a grinding wheel in a desired shape or sharpness, said apparatus comprising in combination,

• (a) means for supporting said wheel for rotation about its axis,
• (b) means for rotationally driving the wheel,
• (c) a truing element having an operative surface conforming to the desired shape for the wheel face,
• (d) means for relatively infeeding said wheel and element to bring said face and operative surface into relative rubbing contact, and
• (e) means for controlling said infeeding and the relative surface speed of said rubbing contact to make the specific truing energy ratio (PWR.sub.t /W') at least approximately equal to a predetermined but adjustable set point value, where PWR.sub.t is the energy expended per unit time in creating said rubbing contact and W' is the volume of material removed from the wheel per unit time.

In a grinding machine having a rotationally driven grinding wheel relatively feedable to bring its face into rubbing grinding contact with a workpiece, so that the face tends to deteriorate from the desired shape therefor, apparatus for truing the wheel to restore its face shape comprising in combination,

• (a) a truing element having an operative surface conforming to the desired shape for the wheel face,
• (b) means for relatively infeeding the wheel and said element to maintain said face and said operative surface in rubbing contact,
• (c) means for sensing the parameters of said rubbing contact to signal at least approximately the specific truing energy ratio with which material is removed from the wheel,
• (d) means for signaling a predetermined but set point value of specific truing energy, and
• (e) means responsive to said means (c) and (d) for correctively adjusting at least one of (i) the relative surface speed of said rubbing contact and (ii) the rate of said infeeding to restore the specific truing energy ratio to the set point whenever it tends to depart therefrom.

The method of truing and conditioning the face of a grinding wheel, said method comprising

• (a) rotationally driving the grinding wheel and relatively feeding the operative surface of a conditioning element into rubbing contact with the wheel face,
• (b) initially conjointly establishing the relative surface speed and feed rate of said rubbing contact to make the specific truing energy ratio fall within a first predetermined range of values, and
• (c) thereafter conjointly establishing the relative surface speed and feed rate of said rubbing contact to make said ratio fall within a second predetermined range of values, said second range being higher than and non-overlapping with said first range,
• whereby the procedure (b) removes material from the wheel relatively rapidly for efficient shaping but leaves the wheel sharp and conducive to producing a rough surface finish on a workpiece, and said procedure (c) thereafter removes material from the wheel relatively slowly and dulls the wheel to make it conducive to producing a finer surface finish on a workpiece.

The method of conditioning a grinding wheel in a manner to generally determine the surface finish it will produce in the grinding of a workpiece, said method comprising

• (a) rotating the wheel and feeding the wheel face into relative rubbing contact with the operative surface of a conditioning element, said surface conforming to the desired shape for the wheel face,
• (b) rotating the wheel and feeding the wheel face into relative rubbing contact with active surface of a workpiece,
• said method being characterized by and including
• (c) during the performance of said procedure (a), controlling the the specific truing energy ratio of the wheel/element interaction to maintain it at least approximately in agreement with a desired set point value, and
• (d) adjusting said set point value, whereby the surface finish smoothness produced on the active surface of the workpiece as a consequence of procedure (b) is related monotonically to the adjusted set point value last-employed in the performance of said procedure (c).

In a grinding machine having a rotationally driven grinding wheel, a workpiece to be ground, and a truing element, said grinding machine including

• (a) means for feeding said wheel relative to the workpiece to create relative rubbing contact and grinding action at the wheel/workpiece interface,
• (b) means for feeding said wheel relative to the truing element to create relative rubbing contact and truing action at the wheel/element interface, and
• (c) a control system characterized by
• (1) means for operating said means (a) and (b) to make said grinding action and truing action occur simultaneously, and
• (2) means for controlling the truing action to maintain the specific truing energy ratio thereof within a predetermined but adjustable range of values.

The method of grinding a workpiece which lacks structural rigidity sufficient to withstand, without deleterious deflection, substantial forces imposed thereon by a grinding wheel, said method comprising

• (a) relatively feeding the workpiece and a rotationally driven grinding wheel into relative rubbing contact to create grinding action, and
• said method being characterized by
• (b) while said procedure (a) as in progress, relatively feeding the operative surface of a conditioning element into relative rubbing contact with the face of the wheel, and
• (c) conjointly establishing the relative surface speed and feed rate of said operative surface and said wheel face to maintain the specific truing energy ratio of the last-named rubbing contact within a predetermined range of values selected to create wheel wear and sharpening,
• whereby the rate of grinding action may be made greater than otherwise possible without exceeding tolerable grinding forces imposed by the wheel on the workpiece.

The method of grinding the work surface of a workpiece with a rotationally driven grinding wheel, said method comprising

• (a) relatively feeding the wheel face into relative rubbing contact with the work surface of the workpiece, and
• said method being characterized by
• (b) while said procedure (b) is being carried out, bringing the operative surface of a truing element into relative rubbing contact with the wheel face during intermittent, spaced time periods, and
• (c) during such time periods, establishing conjointly the relative surface velocity and the relative infeed rate of said operative surface and wheel face to maintain the specific truing energy ratio within a predetermined range of values.

The method of grinding the work surface of a workpiece with a rotationally driven grinding wheel, said method comprising

• (a) relatively feeding the wheel face into relative rubbing contact with the work surface of the workpiece, and
• said method being characterized by
• (b) utilizing a sensing means operatively disposed to sense the wheel face and to produce a signal when the wheel face has deteriorated a predetermined degree from the desired shape,
• (c) in response to each appearance of said signal and while said procedure (a) is being carried out, initiating and executing the following procedure (d) and (d1):
• (d) moving the operative surface of a truing element into relative rubbing contact with the wheel face;
• and
• (d1) establishing conjointly, for a finite time period, the relative surface velocity and the relative infeed rate of said operative surface and wheel face to maintain the specific truing energy ratio within a predetermined range of values.