Gear cutting – milling – or planing – Milling – Including means to infeed rotary cutter toward work
Patent
1987-12-21
1989-06-06
Bishop, Steven C.
Gear cutting, milling, or planing
Milling
Including means to infeed rotary cutter toward work
279 6, 409211, 409214, B23C 702, B23C 112, B23C 328
Patent
active
048367257
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a power-driven milling unit for machine tools, which is movable in a first and a second direction perpendicular to one another, and which are the directions of movement of the longitudinal and cross rests of the machine tool.
Power-driven milling tools or milling tool heads of this kind are today commonly put into the tool holding means of general purpose machine tools, and especially into the tool turrets of numerically controlled lathes in order to be able to perform boring and milling work on a stationary or revolving workpiece, such as, say, oil feed bores or axial or radial keyways. Such lathes usually have only one saddle and one cross slide, that is, a first and a second direction of movement for the tool.
In order to mill an axial slot, for example, with such a system, in a stationary workpiece mounted in the lathe, there have been three different possibilities:
The first possibility is that the axial slot is made on the side of the workpiece, i.e., at the level of the longitudinal axis of the workpiece, by a radially extended end mill. The depth of the slot in this case is adjusted by means of the cross rest, while the length of the groove is produced by running the tool along the saddle. The width of the groove, however, is determined exclusively by the diameter of the end mill, with the resultant disadvantage that a tolerance specified for the slot width can be satisfied, after the end mill is worn, only by replacing the tool with a fresh one. There is no way of resizing the worn end mill. Accordingly, a great number of end mills must be prepared in the case of series production, and tool changing must be performed frequently, and in this case the normal edge life of the end mills, depending on the slot width tolerances, cannot be fully utilized. This involves relatively high manufacturing costs due to the great amount of time spent in tool changing and the incomplete utilization of the theoretically possible tool edge life.
The second possibility is that each of the two side flanks of the axially running slot is produced by one of two end mills which are mounted on different tool holders. Since only one flank is machined by each end mill, the desired precision of the groove width can be achieved in the event of wear by readjusting the two end mills, and is not dependent on the diameter of the individual end mills. The one end mill, therefore, is set just over and the other just under the level of the longitudinal axis of the workpiece. The disadvantage of this is that two separate, power-driven tool heads are required for the two mills, so that it requires two tool chucks instead of the one required in the first solution of the problem.
The third solution is that one end mill is used, as in the first solution, but this has a diameter that is less than the width of the slot that is to be made. The two flanks of the groove, therefore, are made by the same end mill in two different steps. The adjustment of the level of the end mill that is necessary for this purpose in the described arrangement of the workpiece requires, therefore, an adjustment of the end mill in a third direction of movement perpendicular to the directions of movement of the cross rest and saddle. This has been accomplished heretofore by having a third slide enabling the tool to run perpendicular to the saddle and cross rest. Such an additional, third rest, however, signifies a relatively extensive and costly upgrading of the lathe, since such an additional rest has to bear the entire tool holding means, i.e., in the case of an NC lathe, the entire tool turret. Normally a machine investment of this kind would probably not pay, from the economical point of view, if it were made just to avoid the disadvantages of the first solution described.
The invention is therefore addressed to the problem of making it possible, with a minimum of trouble, to achieve an adjustment of the end mill in the third direction, i.e., perpendicular to the first two directions of movement of the saddle and cross rest.
The solutio
REFERENCES:
patent: 1365536 (1921-01-01), Nielsen
patent: 1628975 (1927-05-01), Hawkins
patent: 2219717 (1940-10-01), Swahnberg
patent: 2915949 (1959-12-01), Novkov
Horsky Anton
Kuhn Siegfried
Voss Wolf-Dietrich
Bishop Steven C.
Boehringer Werkzeugmaschinen GmbH
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