Recently, as one of the latest precision machining techniques, the grinding technique using super-abrasive grains is highly noticed, and the diamond grindstone having diamond abrasive grains bound by resin or metal binding material is preferably used as an ideal grindstone for grinding rigid and brittle materials such as ceramics.
In the grinding machine using such super-abrasive grains as the grinding wheel, the grinding wheel was conventionally trued in the following manner.
For example, in the case of a vertical double disk surface grinding machine using metal bond diamond grinding wheel, its truing method is as shown in FIG. 14(a), in which a dressing stone b for truing is inserted between rotating grinding wheels a, a, and the bond (binding material) B of the grindstone surface in the grinding wheels a, a is shaved off by the abrasive grains released from the dressing stone b, and the grinding wheel is trued while dressing the abrasive grains A of the grindstone.
That is, the grinding wheel of super-abrasive grains of the surface grinding machine was trued by shaving off the bond B by using the released abrasive grains from the dressing stone b as the tool, which is known as the lapping technique.
The conventional truing method by such lapping method had the following problems, and its improvement has been demanded.
That is, in truing of grinding wheel by lapping technique, since the grinding wheel is trued by the lapping action of released abrasive grains, sharpness of abrasive grains deteriorates. It also took a long time when truing the grinding wheel by the lapping technique.
In particular, in truing the grinding wheel of double disk surface grinding machine, as shown in FIG. 14(b), if the balance of pressure applied to the dressing stone b is broken by the grinding wheels a, a in the truing process, the arm c supporting the dressing stone b is deflected, and accurate truing of grinding wheels a, a is difficult, and truing of high precision is not expected.
The invention is devised in the light of such problems in the prior art, and it is hence an object thereof to present a truing technique capable of truing the grinding wheel in a short time and at a high precision, in a grinding machine comprising a conductive grinding wheel, and a grinding machine operating on such grinding technique.