Gear cutting – milling – or planing – Milling – Cutter spindle or spindle support
Reexamination Certificate
1999-05-27
2001-07-24
Howell, Daniel W. (Department: 3722)
Gear cutting, milling, or planing
Milling
Cutter spindle or spindle support
C409S135000, C409S137000
Reexamination Certificate
active
06264409
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tool holder clamp device for spindle of a machine tool, and particularly, to a tool holder clamp device for spindle of a screw-fastening type, as well as to a spindle apparatus including such a tool holder clamp device.
2. Description of Relevant Art
As a tool holder clamp device for a spindle for high-speed rotation, there has been proposed in Japanese Patent Application Laid-Open Publication No. 10-76413 (1998) a device in which unbalancing factors are eliminated to suppress increase of inertial force in rotation of a spindle.
This device is a screw-fastening type in which a spindle has a taper hole formed in a distal end part thereof and a tool holder has a shank portion adapted for insertion to and draw-out from the taper hole, and by which the shank portion is clamped in a screw fastening manner. The screw-fastening type tool holder clamp device comprises a clamp bolt member, which has a threaded part provided in a central through-hole or hollow of the spindle communicating with the taper hole and adapted to be screwed in a threaded hole axially formed in the shank portion of the tool holder and which fixes the tool holder by fastening the shank portion by means of the threaded part, and a drive shaft body (as a draw-bar member), which is provided in the central through-hole and axially movable to engage with the clamp bolt member for drive connection therewith to thereby drive the clamp bolt member into rotation. When the spindle rotates, the drive shaft member is separated from the clamp bolt member so that unbalancing factors of the spindle are eliminated, and the spindle has a reduced weight.
In such a screw-fastening type tool holder clamp device, as a clamp bolt member is incorporated to a spindle and not allowed to axially move, when the clamp bolt member is driven into rotation for attachment or detachment of a tool holder, it is necessary to change an axial relative position between a spindle apparatus and the tool holder in accordance with a screw lead.
Therefor, in use of an automatic tool exchange device to effect automatic exchange of tool, there is necessitated a synchronous control between the clamp bolt member to be rotated and the spindle apparatus to be axially moved in conjunction therewith.
However, the clamp bolt member to be separable from a drive shaft body, which serves as a body of rotary drive to rotate the clamp bolt member, is connected thereto by a mating between a polygonal column and a polygonal hole for example, and a quantity of rotation of the rotary drive body does not always coincide with that of the clamp bolt member, so that the rotation quantity of the rotary drive body cannot be based on for control of a rotation quantity of the clamp bolt member. It is thus difficult for a quantity of rotation of the clamp bolt member and a quantity of axial movement of the spindle apparatus to be associated with each other for synchronous control therebetween, with the result that such a conventional screw-fastening type tool holder clamp device is unable to cope with the use of an automatic tool exchange device.
SUMMARY OF THE INVENTION
The present invention has been achieved with such points in view.
It therefore is an object of the present invention to provide a screw-fastening type tool holder clamp device for spindle which can easily cope with the use of an automatic tool exchange apparatus and which is improved such that foreign matters in a mating region between a taper hole of a spindle and a shank portion of a tool holder can be removed in an effective manner and that the spindle to be rotated at high speed can be cooled effectively. It also is an object of the invention to provide a spindle apparatus including such a screw-fastening type tool holder clamp.
To achieve the object, an aspect of the invention provides a tool holder clamp device for spindle for clamping, in a screw-fastening manner, a shank portion of a tool holder to be incorporated to a spindle in a removably fittable manner relative to a taper hole formed at a distal end portion of the spindle, the tool holder clamp device for spindle comprising a clamp bolt member rotatably and axially movably provided in a central through-hole of the spindle communicating with the taper hole, the clamp bolt member having a threaded part to be screwed in a threaded hole axially formed in the shank portion of the tool holder, the clamp bolt member being adapted to fix the tool holder by fastening the shank portion by means of the threaded part, and a drive shaft body rotatably and axially movably provided in the central through-hole of the spindle, the drive shaft body being adapted by axial movement thereof to engage with the clamp bolt member for drive connection therewith to drive the clamp bolt member into rotation.
According to this aspect of the invention, the clamp bolt member is adapted to axially move by a screw lead of a screwed engagement with the tool holder, as it rotates, and the device can easily cope with the use of an automatic tool exchange apparatus without the need of synchronous control between a rotation quantity of clamp bolt member and an axial movement quantity of spindle.
According to another aspect of the invention, the tool holder clamp device for spindle further comprises a thrust roller bearing member disposed in place where the clamp bolt member faces a stepped end face in the central through-hole of the spindle.
According to this aspect of the invention, as the thrust roller bearing member intervenes between the clamp bolt member and the stepped end face in the central through-hole of the spindle, there is achieved a prevention of seizure between the spindle and the clamp bolt member having their faces opposing each other in a thrust direction.
According to another aspect of the invention, the tool holder clamp device for spindle further comprises an air supply hole formed in the drive shaft body for supplying air from a proximal end side of the drive shaft body to a distal end side thereof, and an air discharge hole formed through a core part of the clamp bolt member to receive air supplied from the air supply hole.
According to this aspect of the invention, as air is supplied from the air supply hole to the air discharge hole provided through the core part of the clamp bolt member, discharged air from the air discharge hole to the taper hole blows off foreign matters from between the taper hole and the shank portion of the tool holder, and prevents their accumulation and deposition, and automatic tool exchange can be performed in an ensured manner.
According to another aspect of the invention, the tool holder clamp device for spindle further comprises an air supply hole formed in the drive shaft body for supplying air from a proximal end side of the drive shaft body to a distal end side thereof, and the drive shaft body alternately having large diameter shaft portions slightly smaller in diameter than the central through-hole of the spindle and small diameter shaft portions smaller in diameter than the large diameter shaft portions.
According to this aspect of the invention, as the large diameter shaft portions and the small diameter shaft portions are alternately provided on the drive shaft body, the cooling air path provided between the outer circumference of the drive shaft body and the inner circumference of the central through-hole is changed in sectional area so that discharged air from the distal end part of the air supply hole into the central through-hole has turbulent streams, which flow through the gap between the outer circumference of the drive shaft body and the inner circumference of the central through-hole, and the spindle can be effectively cooled from the central through-hole.
According to another aspect of the invention, the tool holder clamp device for spindle further comprises an air supply hole formed in the drive shaft body for supplying air from a proximal end side of the drive shaft body to a distal end side thereof, and a spiral groove forme
Date Takao
Endo Katsuhito
Kai Yoshiaki
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Howell Daniel W.
Toshiba Kikai Kabushiki Kaisha
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