Automatic tool changing device for a machine tool

Claim 2

An automatic tool changing device for a machine tool having a machine frame and a headstock spindle comprising: a rotatable tool holding drum having a side wall in which are a plurality of spaced tool holding positions for holding a plurality of tools adapted to engage said headstock spindle, said drum being so positioned with respect to said headstock spindle as to present upon rotational movement of said drum a selected tool to said headstock spindle axially spaced from saId headstock spindle but in substantially proper alignment for engagement therewith, means for rotating said drum to being said selected tool substantially in proper alignment with said headstock spindle, a drum support mounted on said headstock, said drum support being laterally movable between a first position in which said selected tool is spaced axially from said headstock spindle and a second position in which said tool engages said headstock spindle, a plurality of locating pins affixed to said wall of said drum, each of said locating pins being associated with one of said tool positions and having a portion of a predetermined diameter, and a conical opening on said frame, said conical opening leading to a cylindrical chamber having said predetermined diameter and an axis parallel to the axis of said spindle for receiving said locating pins when said drum is moved laterally to said second position, whereby said locating pins engage said conical opening to effect a subsequent rotation of said frum to align said selected tool accurately to said headstock spindle.

Claim 3

An automatic tool changing device for a machine tool having a machine frame and a headstock spindle comprising: a rotatable tool holding drum having a side wall in which are a plurality of spaced tool holding positions for holding a plurality of tools adapted to engage said headstock spindle, said drum being so positioned with respect to said headstock spindle as to present upon rotational movement of said drum a selected tool to said headstock spindle axially spaced from saId headstock spindle but in substantially proper alignment for engagement therewith, means for rotating said drum to being said selected tool substantially in proper alignment with said headstock spindle, a drum support mounted on said headstock, said drum support being laterally movable between a first position in which said selected tool is spaced axially from said headstock spindle and a second position in which said tool engages said headstock spindle, a plurality of locating pins affixed to said wall of said drum, each of said locating pins being associated with one of said tool positions and having a portion of a predetermined diameter, and a conical opening on said frame, said conical opening leading to a cylindrical chamber having said predetermined diameter and an axis parallel to the axis of said spindle for receiving said locating pins when said drum is moved laterally to said second position, whereby said locating pins engage said conical opening to effect a subsequent rotation of said frum to align said selected tool accurately to said headstock spindle.

Claim 4

An automatic tool changing device for a machine tool having a machine frame and a headstock spindle comprising: a rotatable tool holding drum having a side wall in which are a plurality of spaced tool holding positions for holding a plurality of tools adapted to engage said headstock spindle, said drum being so positioned with respect to said headstock spindle as to present upon rotational movement of said drum a selected tool to said headstock spindle axially spaced from saId headstock spindle but in substantially proper alignment for engagement therewith, means for rotating said drum to being said selected tool substantially in proper alignment with said headstock spindle, a drum support mounted on said headstock, said drum support being laterally movable between a first position in which said selected tool is spaced axially from said headstock spindle and a second position in which said tool engages said headstock spindle, a plurality of locating pins affixed to said wall of said drum, each of said locating pins being associated with one of said tool positions and having a portion of a predetermined diameter, and a conical opening on said frame, said conical opening leading to a cylindrical chamber having said predetermined diameter and an axis parallel to the axis of said spindle for receiving said locating pins when said drum is moved laterally to said second position, whereby said locating pins engage said conical opening to effect a subsequent rotation of said frum to align said selected tool accurately to said headstock spindle.

Claim 5

A device according to claim 1 wherein said drum support is moved laterally parallel to the axis of said spindle by a hydraulic motor connected between said tool support and said headstock, said hydraulic motor comprising a hydraulic cylinder and a rotary piston operating in said cylinder and having an eccentric pin operating in a slot to impart linear movement to said support.

Claim 6

A device according to claim 2 wherein each of said tool holding positions comprises an opening in said side wall and said tools are mounted upon discs which are received by said openings and held therein by pins radially inserted into openings in said discs, said device further comprising a hydraulic motor mounted on said headstock and having a piston rod acting upon said pins when said support is in said second position to withdraw or insert said pins from said selected tool to respectively free said tool for rotation with said spindle and lock said tool to said disc.

Claim 7

A device according to claim 1, wherein said means for rotating include an electric motor operable for driving said drum in rotation and an electromagnet brake for braking said drum when said selected tool is substantially in proper alignment with said head stock spindle.

Claim 8

A device according to claim 4, wherein said electric motor is reversible, comprising a control circuit for said electric motor for selecting the direction of rotation of said drum which will align said selected tool by the shortest path, said control circuit including means responsive to binary coded number A + R representing respectively the actual position of said drum and the required position of said drum to form the most significant bit of the sum A + R where R is the complement of R and to select the direction of rotation in accordance with the value of said bit.

Claim 9

An automatic tool changing device for a machine tool having a machine frame and a headstock spindle comprising: a rotatable tool holding drum for holding a plurality of tools, said drum being rotatably selectively for bringing a selected tool in correspondence with said headstock spindle for engagement thereby, a reversible electric motor for driving said drum in rotation, an electromagnetic brake operable for braking said drum when said selected tool is so brought in correspondence with said headstock spindle, a plurality of micro-switches for providing a binary coded number A representing the actual positions of said drum, a plurality of sets of cams, each of said sets being mounted on said drum in association with one of said tool positions and operating a corresponding combination of said micro-switches when said tool position is presented to said headstock spindle, an input register for storing a binary coded number R representing the required position of said drum, an inverter means for forming the complement R from said R number, an adder responsive to said micro-switches and said inverter means to provide the most significant bit of the sum A+R, two bistable elements which when set cause said electric motor to rotate in its two directions respectively, and a third bistable element which when set by a signal of assent to rotation of said drum releases said electromagnetic brake and enables said most significant bit to set one of said two elements depending upon whether said bit is ''''0'''' or ''''1,'''' a comparison circuit connected to said input register and said micro-switches, said comparison circuit emitting a coincidence signal when A R, said coincidence signal resetting all three of said elements, a cam-operated switch arranged to provide an aligning signal when said drum is positioned to align said selected tool within a predetermined angular range relative to said headstock spindle, and a further circuit responsive to said aligning signal and said coincidence signal as delayed by a delay circuit to provide an enabling signal allowing movement of said drum laterally toward said spindle.

Claim 10

An automatic tool changing device for a machine tool having a machine frame and a headstock spindle comprising: a rotatable tool holding drum for holding a plurality of tools, said drum being rotatably selectively for bringing a selected tool in correspondence with said headstock spindle for engagement thereby, a reversible electric motor for driving said drum in rotation, an electromagnetic brake operable for braking said drum when said selected tool is so brought in correspondence with said headstock spindle, a plurality of micro-switches for providing a binary coded number A representing the actual positions of said drum, a plurality of sets of cams, each of said sets being mounted on said drum in association with one of said tool positions and operating a corresponding combination of said micro-switches when said tool position is presented to said headstock spindle, an input register for storing a binary coded number R representing the required position of said drum, an inverter means for forming the complement R from said R number, an adder responsive to said micro-switches and said inverter means to provide the most significant bit of the sum A+R, two bistable elements which when set cause said electric motor to rotate in its two directions respectively, and a third bistable element which when set by a signal of assent to rotation of said drum releases said electromagnetic brake and enables said most significant bit to set one of said two elements depending upon whether said bit is ''''0'''' or ''''1,'''' a comparison circuit connected to said input register and said micro-switches, said comparison circuit emitting a coincidence signal when A R, said coincidence signal resetting all three of said elements, a cam-operated switch arranged to provide an aligning signal when said drum is positioned to align said selected tool within a predetermined angular range relative to said headstock spindle, and a further circuit responsive to said aligning signal and said coincidence signal as delayed by a delay circuit to provide an enabling signal allowing movement of said drum laterally toward said spindle.

Claim 11

A device according to claim 6 wherein said comparison circuit is connected to an arresting circuit which is additionally responsive to said assent signal as delayed by a delay circuit to reset all three of said elements if said coincidence signal does not appear prior to the appearance of said delayed assent signal.