SINGLE POWER TOOL CHANGING DEVICE OF CNC MACHINING CENTER

A single power tool changing device of a CNC machining center includes a tool magazine unit, a cam-based tool changing unit, and a power clutch unit. The tool magazine unit includes a tool magazine body, a rotatable disk, and a plurality of tool sets. The cam-based tool changing unit includes a tool change base, a cam mechanism, and a tool changing mechanism. The power clutch unit includes a first force output axle that drives the tool magazine unit to operate, a second force output axle that drives the cam-based tool changing unit to operate, and a power mechanism, which selectively transmits power to the first or second force output axle. As such, the present invention allows for performance of both operations of tool selection and tool change with a single driving power source so as to achieve an advantage of reducing installation cost.

(a) TECHNICAL FIELD OF THE INVENTION

The present invention generally relates to a CNC (Computer Numeric Control) machining center, and more particularly to a single power tool changing device of a CNC machining center that uses a single driving power source to carry out two different operations of tool selection and tool change.

(b) DESCRIPTION OF THE PRIOR ART

Referring toFIG. 1, a conventional CNC machining center10generally comprises a machining spindle head11, a tool magazine unit12, and a tool change unit13. The machining spindle head11has a lower end to which a tool100is mounted and fixed. The tool magazine unit12comprises a tool magazine body121, a rotatable disk122mounted to the tool magazine body121for rotation movement, a plurality of tool receptacles123mounted to the rotatable disk122and respectively receiving various tools100therein, and a first motor124mounted to the tool magazine body121to drive the rotatable disk122to rotate. The tool change unit13comprises a tool change base131, a cam mechanism (not shown) mounted inside the tool change base131, a tool changing arm132rotatably mounted to the tool change base131and driven by the cam mechanism, and a second motor133mounted to the tool change base131to drive the cam mechanism to operate. When a user attempts to carry out a tool selection operation, the first motor124is first actuated to drive the rotatable disk122of the tool magazine unit12to rotate so that the rotatable disk122moves the tool100that is desired by the user to a tool change position at a lower side thereof for being standby. When the user attempts to carry out a tool change operation, the second motor133is actuated to drive the cam mechanism of the tool changer unit13to operate. Based on a predetermined cam route in combination with the operation of a tool change program, the cam mechanism causes the tool changing arm132to rotate in such a way that the two ends thereof are moved to reach the tool change positions of the tool magazine unit12and the machining spindle head11to then simultaneously grip the tools100at both sides and simultaneously remove the tools100of both sides. Afterwards, the tool changing arm132is caused to rotate 180 degrees to switch the positions of the tools100of both sides. Finally, the tool changing arm132simultaneously put the tools100into the tool receptacle123and the machining spindle head11to complete the entire process of the tool change operation.

The tool magazine unit12and the tool changer unit13described above are effective in realizing operations of tool selection and tool change. However, there is a drawback existing in such an arrangement. The conventional CNC machining center10is provided with a first motor124that is provided in the tool magazine unit12to be dedicated for driving the rotatable disk122and a second motor133that is provided in the tool changer unit13to be dedicated for driving the cam mechanism. The first motor124and the second motor133are respectively mounted to the tool magazine unit12and the tool changer unit13in such a way that they are independent of each other. Thus, the entire tool change system requires two motors124,133and the two motors124,133individually need their won servo control circuit and the likes. The more the number of the motors is, the higher the installation cost will be.

SUMMARY OF THE INVENTION

Thus, an object of the present invention is to provide a single power tool changing device of a CNC machining center that allows operations of tool selection and tool change to be carried out with a single power source.

The present invention provides a single power tool changing device of a CNC machining center, which comprises a tool magazine unit, a cam-based tool changing unit, and a power clutch unit, wherein the tool magazine unit comprises a tool magazine body, a rotatable disk that is rotatably mounted to the tool magazine body, a plurality of tool sets mounted on the rotatable disk, and a first rotation member operatively coupled to the rotatable disk, whereby rotation of the first rotation member causes the rotatable disk to rotate to carry out a tool section operation; the cam-based tool changing unit comprises a tool change base disposed at one side of the tool magazine body, a cam mechanism arranged in the tool change base, a tool changing mechanism mounted on the tool change base and driven by the cam mechanism, and a second rotation member operatively coupled to the cam mechanism, the tool changing mechanism comprising a tool changing arm that is rotatably movable, whereby rotation of the second rotation member causes the cam mechanism to operate to have the tool changing arm carry out a tool change operation; and the power clutch unit comprises a fixed seat, a movable seat slidably mounted on the fixed seat, a pusher assembly operable to selectively move the movable seat, a first force output axle mounted on the fixed seat to selectively drive the first rotation member to rotate, a second force output axle mounted on the fixed seat to selectively drive the second rotation member to rotate, and a power mechanism, the power mechanism comprising a motor and a power output spindle that is mounted on the movable seat and is operatively coupled to the motor, whereby the movement of the movable seat caused by the pusher assembly allows the power output spindle to selectively engage with the first or second force output axle for transmission of power.

The efficacy of the present invention is that the power clutch unit is provided with a power mechanism and the power mechanism is capable of selectively driving the tool magazine unit or the cam-based tool changing unit to operate so that the present invention allows operations of tool selection and tool change to be carried out with a single driving power source thereby achieving an advantage of reducing installation cost.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring toFIG. 2, a single power tool changing device of a CNC machining center according to a first embodiment of the present invention generally comprises a tool magazine unit20, a cam-based tool changing unit,30and a power clutch unit40. Next, in the following, the constituent components of each of the above-described units of the present invention, as well as the spatial arrangements thereof, will be described.

Referring toFIGS. 3-8, the tool magazine unit20comprises a tool magazine body21, a rotatable disk22rotatably mounted to the tool magazine body21, a first rotation member23operatively coupled to the rotatable disk22, a plurality of tool sets24mounted and lined up on the rotatable disk22, and a tool guiding mechanism25disposed alt a lower portion of the tool magazine body21to push and drive the tool sets24down to a tool change position. In the instant embodiment, the tool magazine body21comprises a circular mounting211raised from a central portion thereof. The tool magazine body21comprises an open recess formed in an upper portion thereof to define a notch212. The rotatable disk22comprises a circular mounting hole221formed in a center thereof. Arranged in the form of a circumferential array on an inner circumferential surface of the circular mounting hole221is a plurality of cylindrical bearings222, whereby the bearings222are in rolling engagement with the circular mounting211of the tool magazine body21. Although the rotatable disk22carries a large load of gravity of the plurality of tool sets24, the combination described above in respect of the bearings222allows for stable and smooth rotation of the rotatable disk22with respect to the tool magazine body21. The rotatable disk22comprises, in a recessed form, an annual groove223. In the instant embodiment, the first rotation member23generally comprises a first chain231received in the annual groove223and a ring lid232set on the annular seat223to confine the first chain231. The first chain231is a circular chain with flexibility and opposite sides of a pivot joint of each link of the chain is coupled to the rotatable disk22in a pin-and-hole fashion so that the first chain231is fixed to and movable in unison with the rotatable disk22. The manufacture of the chain is simple and the cost is low and requires no high precision of dimensions so that assembling and replacement for maintenance are easy. Compared to the conventional transmission structure where engagement is made between rigid toothed wheels, the chain-based transmission according to the present invention has an effect of lowering down the cost. Each of the tool sets24comprises a tool receptacle241and a tool (not shown) received and retained in the tool receptacle241. The plurality of tool set24is mounted on the rotatable disk22, whereby when a user has made a selection of a desired one of the tools, the rotatable disk22moves desired tool set24to a lower position, where the tool guiding mechanism25is then operated to push and move the tool set24to a tool change position at a lower side to get standby.

The cam-based tool changing unit30comprises a tool change base31set at one side of the tool magazine body21, a cam mechanism32arranged in the tool change base31, a second rotation member33disposed outside the tool change base31and operatively coupled to the cam mechanism32, and a tool changing mechanism34mounted to the tool change base31and driven by the cam mechanism32. The tool change base31has a hollow interior space in which the cam mechanism32and the tool changing mechanism34are mounted. The cam mechanism32and the tool changing mechanism34are of known structures of which the arrangement and operation will not be described. The tool changing mechanism34comprises a rotatable tool changing arm341. The tool changing arm341, under being driven by the cam mechanism32, has two opposite ends that grip tools for tool changing. In the instant embodiment, the cam mechanism32comprises a drive sprocket321arranged externally of the tool change base31. The second rotation member33comprises a second chain331set around the drive sprocket321, whereby with the second chain331driving the drive sprocket321, the cam mechanism32is set in operation and drives the tool changing mechanism34to carry out a tool change operation.

Referring toFIGS. 9-11, the power clutch unit40is mounted outside the tool magazine body21and comprises a fixed seat41, a movable seat42slidably mounted on the fixed seat41, a pusher assembly43for pushing and driving the movable seat42, a first force output axle44rotatably mounted to the fixed seat41, a second force output axle45rotatably mounted to the fixed seat41, a first brake member46mounted to an end of the movable seat42and extending into an interior of the fixed seat41, a second brake member47mounted to an opposite end of the movable seat42and extending into the fixed seat41, and a power mechanism48mounted on the movable seat42. The fixed seat41is arranged at an upper portion of the tool magazine body21and the fixed seat41comprises two slide rails411arranged thereon. The movable seat42is mounted, in a slidable manner, on the two slide rails411. The pusher assembly43may comprise a pneumatic or hydraulic power device or an electromagnetic valve assembly. In the instant embodiment, the pusher assembly43comprises a cylinder431fixed to the movable seat42and an extendible central rod432received in the cylinder431. An end of the central rod432is coupled to the fixed seat41, whereby when the central rod432extends/retracts, the movable seat42is caused, in entirety, to do linear movement along the slide rails411. Also referring toFIGS. 4,6, and7, the first force output axle44comprises a first transmission gear441arranged in the interior of the fixed seat41and a first chain wheel442arranged outside the fixed seat41. The first chain wheel442is forward extended to penetrate through the notch212of the tool magazine body21to engage an external perimeter of the first chain231, so that the first force output axle44may drive the tool magazine unit20to rotate. The second force output axle45comprises a second transmission gear451arranged in the interior of the fixed seat41and a second chain wheel452arranged outside the fixed seat41. The second chain wheel452is set to couple with the second chain331and the drive sprocket321to achieve transmission, whereby the second force output axle45may drive the cam-based tool changing unit30to rotate. The first brake member46and the second brake member47are coupled to the movable seat42and are movable in unison with the movable seat42and the power mechanism48. The first brake member46comprises a first locking toothed wheel461that is engageable, in a separable manner, with the first transmission gear441. The second brake member47comprises a second locking toothed wheel471that is engageable, in a separable manner, with the second transmission gear45I. In the instant embodiment, the transmission gears441(451) and the locking toothed wheels461(471) are combinations of worm and worm gears. It is also possible to use other type of combinations for mating engagement, of which further details will be given hereafter. The power mechanism48comprises a motor481fixed to the movable seat42, a power output spindle482rotatably mounted to the movable seat42and operatively coupled to the motor481, and a drive gear483mounted to an end of the power output spindle482. In the instant embodiment, the motor481comprises a servo motor and the power output spindle482is located between the first force output axle44and the second force output axle45, whereby movement of the movable seat42allows the drive gear483to selectively mate the first transmission gear441or the second transmission gear451for transmission.

The forgoing provides a description of the structure and shape of the single power tool changing device of the CNC machining center according to the present invention. Next, the use and operation of the present invention and performance achieved thereby will be described.

Referring toFIGS. 6,10, and11, when a user wishes to put the tool magazine unit20into operation, the pusher assembly43of the power clutch unit40is caused to move the movable seat42to a first position, where the drive gear483of the power mechanism48and the first transmission gear441of the first force output axle44engage each other for power transmission. The first force output axle44then uses the first chain wheel442to drive the first rotation member23, and the first rotation member23in turn drives the rotatable disk22of the tool magazine unit20to rotate, whereby the tool set24that the user wishes to select is moved to the tool change position at the lower end of the rotatable disk22to complete the tool selection operation. Under this condition, the first locking toothed wheel461and the first transmission gear441that are arranged in the interior of the power clutch unit40are set in a separate condition, while the second locking toothed wheel471is in engagement with the second transmission gear451so that the second force output axle45is set in a locked condition.

Referring toFIGS. 3,7,12, and13, when the uses attempts to put the cam-based tool changing unit30into operation, the pusher assembly43of the power clutch unit40is caused to move the movable seat42to a second position, where the drive gear483of the power mechanism48and the second transmission gear451of the second force output axle45are in engagement with each other. The second force output axle45then uses the second chain wheel452to drive the second rotation member33, and the second rotation member33drives the drive sprocket321of the cam-based tool changing unit30so as to set the cam mechanism32and the tool changing mechanism34in operation, whereby the tool changing arm341is caused to grip the tool set24set at the tool change position and to have the tools that are located on the machining spindle head (not shown) and the tool magazine unit20exchange with each other to thereby complete the tool change operation. Under this condition, the second locking toothed wheel471and the second transmission gear451that are arranged in the interior of the power clutch unit40are set in a separate condition, while the first locking toothed wheel461is in engagement with the first transmission gear441so that the first force output axle44is set in a locked condition. The purposes of setting the first force output axle44under a locked condition is that when the rotatable disk22carries a tool set24, once losing driving power, the rotatable disk22may instantaneously drops due to the weight of the tool set24. For such a reason, the present invention is designed to have the first force output axle44locked in order to avoid the potential risk of sudden drop of the rotatable disk22.

In summary, the present invention provides the single power tool changing device of the CNC machining center generally for overcoming the drawbacks of the conventional tool changing devices. The technical solution of the present invention includes a first rotation member23is provided on the tool magazine unit20for driving the rotatable disk22to carry out a tool selection operation and a second rotation member33is provided on the cam-based tool changing unit30for driving the tool changing mechanism34to carry out a tool change operation and to provide a fixed seat41, a movable seat42, a first force output axle44, a second force output axle45, and a power mechanism48on the power clutch unit40in such a way that the first force output axle44is operable to drive the first rotation member23and the second force output axle45is operable to drive the second rotation member33, so that through controlling a movement of the movable seat42, the power mechanism48is allowed to selectively engage the first force output axle44or the second force output axle45for power transmission. The present invention uses a single set of power mechanism48to serve as power source for the operations of both the tool magazine unit20and the cam-based tool changing unit30. In this way, installation of additional motor481can be avoided so as to greatly reduce the installation cost of the tool change system.

Besides the embodiment described above, the present invention provides additional modifications for various embodiments. Referring toFIGS. 14-18, the present invention provides a second preferred embodiment, which similarly comprises a tool magazine unit50, a cam-based tool changing unit60, and a power clutch unit70. The tool magazine unit50comprises a tool magazine body51, a rotatable disk52, and a first rotation member53. The cam-based tool changing unit60comprises a tool change base61, a cam mechanism62, a second rotation member63, and a tool changing mechanism64. A difference from the first embodiment is that the power clutch unit70is mounted at a central portion of the tool magazine unit50and comprises a fixed seat71, a movable seat72, a pusher assembly73, a first force output axle74, a second force output axle75, and a power mechanism76. The first force output axle74comprises a first chain wheel741mounted thereto, and the first chain wheel741is in engagement with an internal perimeter of the first rotation member53for driving the rotatable disk52to rotate to carry out the tool selection operation. The second force output axle75comprises a second chain wheel751mounted thereto and the second chain wheel751is engageable with the second rotation member63for transmission of power and drives the drive sprocket621of the cam mechanism62to rotate, so as to drive the tool changing mechanism64to carry out the tool change operation. This arrangement similarly achieves the effect of forwarding and changing tools with a single power source. Further, the power mechanism76comprises a motor761, a power output spindle762rotatably mounted to the movable seat72, and a universal joint763coupled between the motor761and the power output spindle762. The motor761is fixedly mounted outside the fixed seat71and the universal joint763is movable with the movable seat72to allow for power transmission to the power output spindle762at any inclination angle. As such, the movable seat72does not carry the weight of the motor761and, even being set in a standstill position, the motor761is allowed to supply, in a normal way, power to the power output spindle762mounted on the movable seat72.

Further, the present invention provides a number of example embodiments of the brake member of the power clutch unit. Referring toFIG. 19, the present invention provides a third preferred embodiment, in which the power clutch unit40I comprises a first force output axle44I, a second force output axle45I, and a linearly movable brake member46I. The brake member46I comprises a spur gear461I mounted thereto. The spur gear461I is selectively engageable with the first force output axle44I or the second force output axle45I to set up a locked condition therewith.

Referring toFIG. 20, the present invention provides a fourth preferred embodiment, in which the power clutch unit40II comprises a first force output axle44II, a second force output axle45II, and a linearly movable brake member46II. The brake member46II comprises two friction surfaces461II. The two friction surfaces461II are respectively engageable with the first force output axle44II and the second force output axle45II to set up a locked condition therewith.

Referring toFIG. 21, the present invention provides a fifth preferred embodiment, in which the power clutch unit40III comprises a first force output axle44III, a second force output axle45III, and a linearly movable brake member46III. The brake member46III has two ends to which two bevel gears461III. The two bevel gears461III are respectively engageable with the first force output axle44III and the second force output axle45III to set up a locked condition therewith.