Clamping device

Patent metadata

Field	Value
Publication number	US-12158169-B2
Application number	US-202218283545-A
Country	US
Kind code	B2
Filing date	Feb 7, 2022
Priority date	Mar 24, 2021
Publication date	Dec 3, 2024
Grant date	Dec 3, 2024

Abstract

A clamping device ( 100 ) includes a first movable member ( 210 ) that is movable along an extending direction of a first body interior space ( 120 ), a disc spring ( 260 ), an annular spring ( 270 ), a spring ( 280 ) and a collet ( 300 ). A driving mechanism ( 400 ) has a second movable member ( 430 ) that moves along an extending direction of a second body interior space ( 130 ) with rotation of a rotary member ( 410 ). When the rotary member is rotated in one direction, the first movable member moves toward an oil-filled closed space ( 121 ) and the clamping device is set to a clamping mode that will hold a tool holder ( 510 ). On the other hand, when the rotary member is rotated in the opposite direction, the first movable member moves towards the side opposite of the oil-filled closed space and the clamping device is set to an unclamping mode that will release the tool holder.

First claim

The invention claimed is:

1. A clamping device configured to clamp a member having a shank part in which a recess is formed, comprising:
a body, a clamping mechanism and a driving mechanism, wherein:
the body has a first body interior space, a second body interior space and a communication passage,
the clamping mechanism has a first movable member that is movable along an extending direction of the first body interior space, a first chamber having a volume that changes in response to movement of the first movable member, a first elastic member that generates an elastic force that urges the first movable member to move relative to the body in a first direction that reduces the volume of the first chamber, and a collet having a first projection that is engageable with the recess of the member to be clamped,
the collet is settable to a clamping mode in which the first projection becomes engaged with the recess in response to movement of the first movable member in the first direction, and is also settable to an unclamping mode in which the engagement between the first projection and the recess is released in response to movement of the first movable member in a second direction that increases the volume of the first chamber,
the driving mechanism has a second movable member that is movable along an extending direction of the second body interior space, and a second chamber having a volume that changes in response to movement of the second movable member,
the communication passage fluidly connects the first chamber and the second chamber,
a power transmitting medium is filled in the first chamber, the second chamber and the communication passage,
the first chamber has a first cross-sectional area that is larger than a second cross-sectional area of the second chamber, and
the clamping device is configured such that:
movement of the second movable member in a third direction that increases the volume of the second chamber causes the first movable member to move in the first direction due to the elastic force of the first elastic member, and thereby causes the collet to be set to the clamping mode,
movement of the second movable member in a fourth direction that reduces the volume of the second chamber causes the first movable member to move in the second direction against the elastic force of the first elastic member and thereby causes the collet to change to the unclamping mode.

2. The clamping device as defined in claim 1 , wherein:
the driving mechanism includes a rotary member,
the second movable member is configured to be movable along the extending direction of the second body interior space in conjunction with rotation of the rotary member, and
the clamping device is configured such that:
rotation of the rotary member in one direction causes the second movable member to move in the third direction, and
rotation of the rotary member in an opposite direction causes the second movable member to move in the fourth direction.

3. The clamping device defined in claim 1 , wherein:
the shank part of the member to be clamped has a shank part inner peripheral surface that defines a shank part interior space having an opening at one end, and the recess is formed in the shank part inner peripheral surface,
the first movable member includes a first piston that defines the volume of the first chamber, and a first shaft member provided on a side of the first piston that is opposite to the first chamber, the first shaft member extending along the extending direction of the first body interior space,
the collet comprises a plurality of collet members disposed around the circumferential direction on the radially outer side of the first shaft member,
each of the collet members has a collet member inner peripheral surface, a collet member outer peripheral surface, and the first projection that protrudes radially outward from an end part disposed on a side that is opposite to the first chamber,
each of the collet member inner peripheral surfaces has, when viewed in cross-section taken along the extending direction of the first shaft member, a first collet member inner peripheral surface portion, and a second collet member inner peripheral surface portion that is formed on a side of the first collet member inner peripheral surface portion opposite to the first chamber and extends at an inclination angle θ to an extending direction of the first collet member inner peripheral surface portion, the inclination angle θ being set such that the distance between an extension line of the first collet member inner peripheral surface portion and the second collet member inner peripheral surface portion increases from the first chamber side toward the opposite side to the first chamber, and
the clamping device is configured such that:
movement of the first piston in the first direction causes the first collet member inner peripheral surface portions of the collet members to move toward the first shaft member and thereby causes the collet to be set to the clamping mode, and
movement of the first piston in the second direction causes the second collet member inner peripheral surface portions of the collet members to move toward the first shaft member and thereby causes the collet to be changed to the unclamping mode.

4. The clamping device as defined in claim 3 , wherein:
the clamping mechanism includes a second elastic member,
the second elastic member generates an elastic force that urges the first collet member inner peripheral surface portions of the collet members to move toward the first shaft member, and
the clamping device is configured such that:

movement of the first piston in the first direction causes the first collet member inner peripheral surface portions of the collet members to move toward the first shaft member due to the elastic force of the second elastic member, and
movement of the first piston in the second direction causes the second collet member inner peripheral surface portions of the collet members to move toward the first shaft member against the elastic force of the second elastic member.

5. The clamping device as defined in claim 4 , wherein:
each of the collet members has a second projection protruding radially outward at an end part disposed on a side closest to the first chamber,
the first shaft member has an abutment part configured to be abuttable on the second projections of the collet members, and
the clamping device is configured such that:
movement of the first piston in the first direction causes the abutment part of the first movable member to separate from the second projections of the collet members and cause the first collet member inner peripheral surface portions of the collet members to move toward the first shaft member due to the elastic force of the second elastic member, and
movement of the first piston in the second direction causes the abutment part of the first movable member to abut on the second projections of the collet members and thereby apply a force that moves the second projections radially outward and move the second collet member inner peripheral surface portions of the collet members toward the first shaft member against the elastic force of the second elastic member.

6. The clamping device as defined in claim 3 , wherein:
the first shaft member has a projection protruding radially outward at the end part opposite to the first chamber, and
the clamping device is configured such that:
movement of the first piston in the first direction causes the projection of the first shaft member to abut on a portion of the second collet member inner peripheral surface portions of the collet members and thereby apply a force that moves the second collet member inner peripheral surface portions away from the first shaft member, and
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Assignees

• Nt Tool Kk
• Dmg Mori Co Ltd

Inventors

• Ishikawa Hitoshi
• Moriya Yusuke

Classifications

• F16B21/16

  with grooves or notches in the pin or shaft · CPC title

• F16B21/125

  radially resilient or with a snap-action member, e.g. elastic tooth, pawl with spring, resilient coil or wire · CPC title

• F16B4/002

  engaging or disengaging by means of fluid pressure · CPC title

• F16B2200/406

  Clamping parts being collars, bushings or wedges · CPC title

• B23B31/302

  Hydraulic equipment, e.g. pistons, valves, rotary joints · CPC title