Abrading – Abrading process – With critical temperature modification or control of work or...
Reexamination Certificate
2000-06-19
2002-09-24
Rose, Robert A. (Department: 3723)
Abrading
Abrading process
With critical temperature modification or control of work or...
C451S450000, C451S488000
Reexamination Certificate
active
06454636
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for supplying coolant in the grinding machine, while a grinding machine grinds, for grinding a workpiece by rotating a grinding wheel, and more particularly to the method and the apparatus for supplying the coolant while the grinding machine performs a creep feed grinding.
2. Description of the Related Art
In the grinding machine, a main spindle is rotated for grinding a workpiece with a grinding wheel under the condition that the grinding wheel is mounted on the main spindle movable relative to the workpiece. A coolant supply apparatus for supplying coolant (cutting fluid, grinding fluid, and the like) is provided in the grinding machine.
The coolant supply apparatus injects the coolant for cooling a grinding point at which the grinding wheel grinds the workpiece, and the coolant cools down the vicinity of the grinding point to thereby prevent a heat generation while the grinding machine grinds.
It is ideal that the coolant is injected in a tangential direction at the grinding point. However, unlike another tool in other machine tools, a diameter of the grinding wheel for grinding the workpiece is gradually decreased by wearing and dressing of the grinding wheel as the working for grinding the workpiece is advanced.
Accordingly, when a nozzle is mounted on a cover of a grinding wheel and the coolant for cooling the grinding point is injected in a direction of a tangential line of the grinding wheel as in a surface grinding machine, the coolant does not come to impinge against the grinding wheel as the diameter of the grinding wheel is gradually decreased.
Accordingly, there is a conventional technical approach that a nozzle is provided in advance at a predetermined position in a direction slightly slanted relative to the tangential line and the coolant is injected by the nozzle to cool only the vicinity of the grinding point.
Also, in order to prevent the loading chips on the grinding wheel, it is preferable that the coolant for cleaning is injected on a periphery of the grinding wheel. Therefore, there is also a technical approach that the coolant is injected onto a periphery at an intermediate portion between the grinding point and the cleaning position of the grinding wheel so that a cooling operation of the grinding point and a cleaning operation of the grinding wheel may be simultaneously performed by a single nozzle.
By the way, in order to stably grind, it is one of the important factors to always sufficiently supply the coolant at least to the grinding point without failure while the grinding wheel grinds.
While the grinding machine performs the creep feed grinding, a cutting amount of the grinding wheel to the workpiece is increased and the grinding wheel is moved at a low speed to grind a profile of the workpiece, and the like. In particular, in the case in which the creep feed grinding is carried out, in comparison with a traverse grinding or the like it is important to sufficiently supply the coolant without failure while the grinding machine grinds.
However, in case of the above-described prior art for cooling down only the vicinity of the grinding point, since it is impossible to prevent the loading chips on the grinding wheel, there is a fear that it comes to be difficult to perform the creep feed grinding. Namely, a grinding burn occurs on a surface, to be ground, of the workpiece and a grinding force is increased, disadvantageously.
Also in case of the above-described prior art for simultaneously performing the cooling operation of the grinding point and the cleaning operation of the grinding wheel with the single nozzle, there is a tendency that the cooling of the grinding point with the coolant gets to be insufficient. It is preferable that the coolant for cleaning is injected in a direction (i.e., normal line direction) perpendicular to the periphery (grinding circumferential surface) of the grinding wheel.
However, in case of the above-described prior art, there is a fear that an injecting direction of the coolant for cleaning is remarkably shifted from the normal line relative to the periphery of the grinding wheel and as a result a cleaning effect of the coolant gets to be degraded. Namely, also in this prior art, it is impossible to prevent the grinding burn and the increasing of the grinding force.
In another piece of the prior art, a nozzle is provided on a tip end of an arm of a robot fixed to a machine body and the arm is moved in a desired direction to supply the coolant. However, in this case, a movable range of the arm is restricted. For this reason, depending upon the relationship a shape of the workpiece to the grinding point positioned between the grinding wheel and the workpiece, the arm cannot reach the vicinity of the grinding point thereby to be unable to inject the coolant without failure.
Thus, if the sufficient amount of coolant were not supplied to the periphery of the grinding wheel and the grinding point, the grinding comes to be instable and the damage of the grinding wheel occurs and it becomes to be difficult to favorably grind the workpiece.
SUMMARY OF THE INVENTION
In order to overcome the above-noted defects, an object of the present invention is to provide a method and an apparatus for supplying coolant in a grinding machine in which, even if a diameter of a grinding wheel of the grinding machine is changed, the coolant is always injected along a tangential line of the grinding wheel to a grinding point at which the grinding wheel grinds a workpiece and is always injected, substantially in a direction perpendicular to a periphery of the grinding wheel, to the periphery away from the grinding point to thereby make it possible to continuously and stably grind.
Another object of the present invention is to provide a method and an apparatus for supplying coolant in a grinding machine in which, even if the diameter of the grinding wheel of the grinding machine is changed, the coolant is injected to the grinding point along the tangential line on both sides of the grinding wheel to thereby make it possible to continuously and stably grind.
In order to attain these and other objects, according to the present invention, there is provided a method for supplying coolant in a grinding machine, while the grinding machine grinds, which grinds a workpiece by rotating a grinding wheel mounted on a main spindle and by relatively moving the workpiece and the grinding wheel along at least three mutually transverse axes including a direction parallel with an axis of the main spindle, the method comprising the following steps of: mounting on a moving member at least one first nozzle, for cooling a grinding point at which the grinding wheel grinds the workpiece, and at least one second nozzle for cleaning a periphery of the grinding wheel; and moving the moving member in a direction substantially identical with a first normal line, relative to the grinding wheel, which is positioned at a first predetermined angle away from a reference straight line passing through the grinding point and being perpendicular to the axis of the main spindle, whereby the first nozzle injects the coolant with an injecting outlet port directed in a direction substantially identical with a tangential line, of the grinding wheel, passing through the grinding point, and the second nozzle injects the coolant with an injecting outlet port directed in a direction substantially identical with a normal line relative to the grinding wheel.
It is preferable that the moving member is movable in correspondence with a changing diameter of the grinding wheel, and while the diameter of the grinding wheel is changing, the injecting outlet port of the first nozzle is always directed in the direction substantially identical with the tangential line, of the grinding wheel, passing through the grinding point, and the injecting outlet port of the second nozzle is always directed in the direction substantially identical with the normal line relative to the grinding wheel.
Prefer
Armstrong Westerman & Hattori, LLP
Hitachi Seiki Co., Ltd.
Rose Robert A.
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