Automatic tool changer

Details Automatic tool changer Automatic tool changer

1993-09-28

1996-03-19

Bishop, Steven C.

Tool changing

Including machine tool or component

Rotary spindle machine tool

483 54, B23Q 3157

Patent

active

054999634

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to an automatic tool changer used for machine tools such as CNC drills. More particularly, the invention relates to an automatic tool changer which is adapted to decrease the relative velocity between the turret and the spindle of the machine tool sufficiently by moving the turret, relative to the spindle, in the vertical direction when the turret with tools swings toward the spindle for a tool change, whereby the shock generated at the tool change is eliminated. Furthermore, the relative movement between the turret and the spindle in the vertical direction also reduces the distance that the spindle head of the machine tool needs to move, which reduces the time required for the tool change and the dimensions of the machine tool.
Furthermore, the invention relates to an automatic tool changer having a speed reducer within the turret in order to increase the indexing speed of the turret, whereby the time required for changing the tools is reduced.
Furthermore, the invention relates to a speed reducer. More particularly, the invention relates to a novel speed reducer which is suitable for use in the driving unit for the turret of the automatic tool changer.


BACKGROUND ART

Machine tools with an automatic tool changer, in particular CNC drills, are widely used in the field of machine tools. Such automatic tool changers are known, for example, from Japanese Unexamined Patent Publication No. 2-15935 and from Japanese Unexamined Patent Publication No. 2-48146.
A prior art automatic tool changer, as shown in FIG. 16, comprises a turret 74 holding a plurality of tools positioned on its peripheral. When a tool-change command is executed, firstly, orientation is carried out. In orientation, the angular position of a key on a spindle, on which a tool (or tool holder) 70 is mounted, is adjusted to a given angular position. Sequentially, a spindle head 60 is raised with the angular position of the spindle maintained. As the spindle head is raised, a cam 62 is engaged with a lever 64, then the lever 64 is rotated by the cam 62. The rotation of the lever 64 is transmitted to a crank 68 through a link 66 provided on an end of the lever 64. Thus, the crank 68 rotates (in the following, the rotation of the crank and the turret is referred to as a swing movement), and a grip 72 arranged on the periphery of the turret 74 approaches the tool holder 70 mounted on the spindle. Then, the grip 72 engages with the tool holder 70 and grasps it. Thereafter, the spindle head 60 is further raised so that the tool holder 70 is removed from the spindle. When the tool holder 70 removed from the spindle, an indexing of the turret 74 is carried out by the rotation of the spindle with a spindle gear 76 being engaged with a turret gear 78. Thus, a desired tool is selected from among the tools held on the turret 74. Sequentially, the spindle head 60 is lowered and the turret gear 78 is disengaged from the spindle gear 76, during which another orientation is carried out in order to correct the discrepancy of the angular position of the spindle, since the angular position of the spindle may be different from the given angular position due to the rotation of the spindle for indexing the turret. When the spindle head 60 is lowered, the tool holder grasped by the grip 72 is mounted on the spindle and the tool change operation is completed.
The conventional automatic tool changer generates shock due to the swing movement of the turret 74 when the grip 72 grasps the tool holder mounted on the spindle or the tool holder grasped by the grip 72 is mounted on the spindle. In order to reduce the shock, in the conventional automatic tool changer, the feed velocity of the vertical movement of the spindle head is reduced when the shock is generated. Thus, the conventional automatic tool changer has a disadvantage that it takes long time for a tool change because of the reduction of the feed velocity.
Furthermore, in order to remove the tool holder from the spindle, in the conventional automatic tool changer, the spind

REFERENCES:
patent: 4870744 (1989-10-01), Araki et al.
patent: 4873756 (1989-10-01), Yamane et al.
patent: 5134767 (1992-08-01), Yasuda
Patent Abstracts Of Japan, vol. 10, No. 59 (M-459), Mar. 8, 1986 & JP-A-60 205 058.

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