Gear cutting – milling – or planing – Milling – With cutter holder
Patent
1993-11-30
1995-02-14
Briggs, William
Gear cutting, milling, or planing
Milling
With cutter holder
408239R, B23C 900, B23B 3100
Patent
active
053889363
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
This invention relates to a fastening device for a machine tool such as for the fastening of a milling tool to a milling tool mandrel, or a rotatable carrier for boring or milling machines or the like.
2. Description of the Prior Art
SE,B, 409 832 discloses a device for the fastening of a tool holder wherein an axial screw is tightened rigidly in a bore of the center trunnion of the mandrel. The axial screw has a saucer like head with obliquely arranged lower side and serves as fastener for a tool holder pushed onto and over the trunnion and the axial screw. The device has radially arranged locking screws with conical ends displaceable to engage the obliquely arranged lower side of the head of the axial screw.
The intention behind the known device was to facilitate the changing of tools earlier performed by manipulating a locking screw accessible from the opposite end of the tool holder forcing same into and out from the threaded bore at the mandrel trunnion.
By utilizing a central holding screw having a saucer shaped head with an inwardly inclined inner side, the loosening and fastening operations are facilitated. However, by moving the area of engagement for the locking elements or screws so far away axially from the cooperating axial abutment faces, the stability is endangered. This especially occurs when the tool holder sleeve to be slided onto the mandrel trunnion is too short, as when different makers have different dimensions. The axially acting moment of the inclined surface engaging conical ends of the locking screws will be insufficient to press the sleeve with sufficient force against the abutment face of the mandrel especially when the points of the locking screws meet the axially oriented fastening screw shank. The locating of the locking screws outside the rigid and stable mandrel trunnion might result in heavy wear because of the leverage occurring between the tool holder and mandrel upon operation of the milling tool.
SUMMARY OF THE INVENTION
It has been noted that the axial dimension of the central trunnion of milling machine mandrels and the like deviate from the standard or given dimension and, even if the deviation is relatively seen very small, it might result in the tool holder not engaging the abutment face properly. Similarly, the sleeve portion of the tool holder oftentimes does not meet the standard or given dimension being either too long or too short axially. The drawbacks mentioned above concerning the known device is the more pronounced if also the dimensions of the cooperating parts are faulty. An object of this invention is to provide a fastening device which, independently of deviations from given dimensions, ensures a stable fastening.
The invention is based on a milling machine mandrel trunnion having a threaded central bore and this trunnion is used as support for a specific sleeve according to the invention. The sleeve has a circumferential V-groove and also, at its one end face, recesses adapted to the locking wedge of the mandrel. A fastening screw having an essentially flat disc like head is adapted to be threaded into the central trunnion bore until its head engages the outer end face of the sleeve pressing the sleeve inwardly towards the opposite facing end surface of the mandrel. The tool holder or the like has a central opening closely fitting onto the sleeve and, recesses at the inner end of the holder communicating with the recesses for the locking wedge of the mandrel. The tool holder body also presents three radially arranged threaded bores directed towards the center of the central opening for locking screws, each having a conical inner end. The screws being adapted to engage the V-groove of the sleeve secured onto the mandrel trunnion.
BRIEF DESCRIPTION OF THE DRAWING
One embodiment of the device according to the invention will be described in detail in the following with references to the attached drawing, which schematically and in a partial sectional view shows a portion of a milling
REFERENCES:
patent: 4813831 (1989-03-01), Reinauer
patent: 4913607 (1990-04-01), Von Haas
patent: 4915523 (1990-04-01), Andersson
patent: 5040931 (1991-08-01), Spivey et al.
patent: 5212872 (1993-05-01), Spivey et al.
Derwent's abstract, No. 88-247936/35, SU 1 373 496, publ. week 8835 (LENGD PARGOLOVSK WK).
Briggs William
Mircona AB
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