Gear cutting – milling – or planing – Milling – With cutter holder
Reexamination Certificate
1999-04-12
2001-02-13
Howell, Daniel W. (Department: 3722)
Gear cutting, milling, or planing
Milling
With cutter holder
C074S573110, C279S125000, C279S132000, C279S157000, C408S143000, C408S23900A
Reexamination Certificate
active
06186712
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a holder for a tool such as a tap, an end mill, a drill, an internal cutting tool, or an abrasive grindstone.
2. Prior Art
In machining by a machine tool such as a milling machine, a boring machine, a lathe or a polishing machine, the working accuracy is influenced much by the presence or absence and the magnitude of imbalance in weight, in a circumferential direction, of a rotary shaft (that is, a spindle) of a machine tool, a rotating tool or the like. Therefore, in machining of the type mentioned, it is important to reduce the imbalance of a rotary shaft and a rotating tool as far as possible in order to raise the working accuracy.
As one of tool holders which can adjust a rotary shaft and a rotating tool against imbalance, a tool holder is available wherein a holder body having a first section in the form of a bar to be attached to a machine, a second section in the form of a bar coaxially extending from one end of the first section and a flange provided at a boundary portion between the first and second sections is used and a plurality of threaded holes which are opened toward the side of the second section are formed at intervals in a circumferential direction in the flange while screw members are screwed into one or more of the threaded holes in accordance with a direction of imbalance to be eliminated (U.S. Pat. No. 5,096,345, No. 5,033,923 and No. 5,125,777).
However, with the tool holder described above, since the flange thereof to be gripped by an automatic tool exchanging machine which automatically attaches and removes a tool to and from a machine tool together with the tool holder has threaded holes formed therein, the second section of the holder body makes an obstruction to an operation for forming the threaded holes in the flange, and as a result, it is difficult to form a plurality of threaded holes at angularly equal distances and imbalance in weight occurs with the holder body itself.
As another one of tool holders, a tool holder is available wherein a balance ring for balancing is attached to the flange of the holder body (WO95/26258). With this tool holder, since a recess for receiving the balance ring is opened to the first section side at which the tool holder is attached to a rotary shaft of a machine tool, the first section of the holder body makes an obstruction to an operation for forming such a recess on the flange, and as a result, it is difficult to form such a recess accurately and precisely and imbalance in weight occurs with the holder body itself.
Further, with the second-mentioned conventional tool holder described above, since the balance ring is attached to the attaching side to the rotary shaft, before the tool holder is attached to the rotary shaft, the balance ring must be attached to the tool holder and a screw for balancing must be attached to the balance ring from the rotary shaft side of the machine tool. Accordingly, it is difficult to balance the rotary shaft, and particularly after the tool holder is attached to the rotary shaft, it is very difficult to perform balancing.
SUMMARY OF THE INVENTION
Therefore, in a tool holder, although the balance in weight of the holder body itself is very small, it is important to make it possible to perform balancing in weight of a rotary shaft, the tool and so forth readily in a condition where the holder body is attached to the machine.
A tool holder of the present invention comprises a holder body, a ring for receiving part of the bolder body, and an assembling device for removably assembling the ring to the holder body. The holder body has a first section to be attached to a machine and a second section coaxially extending from the first section. The first section and the second section respectively define one end and the other end of the holder body. The holder body further has a contacting portion with which at least a part of the ring facing the one end side is brought into contact.
The tool holder is attached at the first section thereof to a rotary shaft of a machine such as a machine tool, and a tool is attached to the second section. The ring is attached to the holder body from the other end side and is removably assembled to the holder body by means of the assembling device in a condition where at least a part of the ring comes into contact with the contacting portion of the holder body. Weight imbalance can be eliminated, for example, by disposing a ring corresponding to an imbalance amount to be eliminated on the holder body or by assembling a balancer corresponding to an imbalance amount to be eliminated to the ring.
According to the present invention, since at least part of the ring facing the one end side is brought into contact with the contacting portion of the holder body, the ring is attached stably to the holder body. Further, since the ring can be attached to and removed from the holder body from the other end side, that is, from the tool attaching side in a condition where the holder body is attached to the machine, weight imbalance elimination can be performed readily. Furthermore, since a plurality of threaded holes or recesses for balancer need not to be formed on the flange, the holder body with very small imbalance in weight can be produced readily.
The ring may have an outer peripheral face eccentric with respect to the holder body. With this construction, since the ring itself has imbalance in weight, weight imbalance of the rotary shaft, the tool and so forth can be cancelled by the imbalance in weight of the ring itself, and as a result, by using a ring corresponding to the imbalance amount to be eliminated, balancing in weight can be performed readily over a wide range.
The ring may have a plurality of holes angularly spaced from each other around an axis of the ring, and the holes may be opened at least toward the one end side or an outer periphery side of the ring. In this instance, at least one of balancers can be disposed in the hole. With this arrangement, since the balancer can be disposed at or attached to and removed from the hole from the other end side or the outer periphery side of the ring, balancing can be performed more readily and finely.
Each of the holes may be a threaded hole which extend at least in an axial direction of the holder body. Therefore, a screw can be screwed into the threaded hole and can be held in a condition where an end thereof is pressed against the contacting portion or the bottom of the threaded hole. As a result, loosening of the screw is prevented by a frictional engaging force between the end of the screw and the bottom of the threaded hole or the contacting portion.
Each of the holes may be a threaded hole which extends at least in an axial direction of the holder body and outwardly in a radial direction of the ring in such a manner as to come outwardly in radial directions of the ring toward the one end side. Therefore, even if a centrifugal force which arises from rotation of the tool holder acts upon the screw screwed in a threaded hole, since the centrifugal force acts in a direction in which the screw is moved toward the contacting portion, coming off of the screw from the hole is prevented with certainty.
Each of the holes may be a threaded hole which extends at least in an axial direction of the holder body such that the axis thereof has an angle with respect to imaginary lines which pass the axis of the holder body and the center in longitudinal direction of the hole so that a portion thereof adjacent to the one end may not come inwardly in radial direction of the ring with respect to a portion thereof adjacent to the other end. Therefore, even if a centrifugal force which arises from rotation of the tool holder acts upon a screw screwed in a threaded hole, since the centrifugal force does not act in a direction in which the screw is removed from the threaded hole, coming off of the screw from the hole is prevented with certainty. Further, since the threaded hole is opened at locations away from the second section, the second sectio
Graybeal Jackson Haley LLP
Howell Daniel W.
Manyo Tool Kabushiki Kaisha
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