Patent Description:
In the manufacture of toothed workpieces such as gears (for example spur gears, helical gears and bevel gears; shafts with toothed portions and/or elements; and splines), it is common for a sharp corner or edge to be formed at the intersection of a tooth flank or tooth slot with an end face of the workpiece. In most cases, it is desirable to remove the corner or edge portion of a tooth via a process known as chamfering.

Chamfering a tooth edge can be carried out with a variety of tools including, but not limited to, fly cutter, milling tool including a pencil mill, hob, profile cutter, grinding wheel, peripheral cutter, ChamferCut-type tool as disclosed in <CIT>, skiving cutter, rolling deburring wheel as disclosed in <CIT>, etc. As is apparent to the skilled artisan, the particular tool is dependent upon, among other things, workpiece geometry, manufacturing process parameters, machine constraints, productivity requirements and personal preferences.

It is known from <CIT> to provide a device movable along one or more axes wherein a chamfering tool may be swiveled <NUM> degrees so that the cutting direction of the chamfering tool can be reversed at opposite ends of a tooth slot. While the direction of rotation of the drive of the tool remains the same in both swivel positions, the cutting directions of the tool are opposite to each other so that the tooth can be cut from inside to outside on the two end faces of the workpiece in both machining positions.

<CIT> teaches a chamfering device capable of linear motion along three perpendicular linear axes and well as swiveling about a pivot axis. The device includes two chamfering cutters located on the same tool spindle for chamfering a workpiece on two different sides.

<CIT> discloses a multi-axis positionable chamfering device comprising a pair of skiving tools with the tool axes being inclined toward one another and with each axis being angularly adjustable through two different angles.

For certain workpieces, however, a single type of chamfering tool may not be sufficient. Some workpieces (e.g. shafts) may have a plurality of gears located thereon with the gears having different sizes and/or tooth geometries. The edge of the root portion of certain gears may be difficult to chamfer with the same tool as is used for the edge of a tooth profile. A chamfering tool suitable for chamfering one gear may not be suitable for chamfering another gear on the same shaft.

There remains a need for a chamfering device having greater flexibility so as to enhance chamfering capabilities given the large variety of workpiece types, sizes and geometries.

<CIT> discloses a machine tool for contemporary cutting of multiple faces from free end of a workpiece.

<CIT> discloses a machine tool with inclined work holding table.

The invention provides a chamfering device for chamfering toothed workpieces in accordance with claim <NUM>. The device has a chamfering head which includes a first axis of rotation for rotation of a first chamfering tool and a second axis of rotation for rotation of a second chamfering tool wherein the first and second chamfering tools are of different types. The chamfering head is operable to rotate a first chamfering tool about the first axis of rotation thereby enabling chamfering by a first material removal method. The chamfering head is further operable to rotate a second chamfering tool about the second axis of rotation thereby enabling chamfering by a second material removal method wherein the first material removal method and the second material removal method are different from one another.

The first and second axes of rotation are not coincident with one another and in a more preferred arrangement, the first tool axis and the second tool axis are arranged perpendicularly with respect to one another.

The invention is capable of other constructions and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purposes of description and should not be regarded as limiting.

The details of the invention will now be discussed with reference to the accompanying drawings which illustrate the invention by way of example only. In the drawings, similar features or components will be referred to by like reference numbers. For a better understanding of the invention and ease of viewing, doors and/or any internal or external guarding have been omitted from the drawings.

The use of "including", "having" and "comprising" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The words "a" and "an" are understood to mean "one or more" unless a clear intent to limit to only one is specifically recited. Although references may be made below to directions such as upper, lower, upward, downward, rearward, bottom, top, front, rear, etc., in describing the drawings, these references are made relative to the drawings (as normally viewed) for convenience. These directions are not intended to be taken literally or limit the present invention in any form. In addition, terms such as "first", "second", "third", etc., are used to herein for purposes of description and are not intended to indicate or imply importance or significance.

The present invention comprises a toothed workpiece chamfering device having a chamfering head which includes a first tool axis of rotation and a second tool axis of rotation. The chamfering head is operable to rotate a first chamfering tool about the first axis of rotation thereby enabling chamfering of a toothed workpiece by a first material removal method. The chamfering head is further operable to rotate a second chamfering tool about the second axis of rotation thereby enabling chamfering of a toothed workpiece by a second material removal method. The first chamfering tool and the second chamfering tool are different from one another and the first material removal method and the second material removal method are also different from one another.

<FIG> show the inventive chamfering head <NUM> which is part of a chamfering device such as illustrated by <FIG>. The chamfering head <NUM> includes a body portion <NUM> capable of supporting at least two tools for rotation, preferably tools that are different from one another such as different types of tools that enable different material removal methods. A first tool <NUM>, preferably a cutting tool such as a fly cutter with one or more indexable inserts <NUM>, is releasably attached to body <NUM>, via suitable tool-holding equipment (not shown), for rotation about a first tool axis B via a motor <NUM> such as a servo motor.

A second tool <NUM>, preferably a cutting tool such as a milling tool, for example a pencil mill, is releasably attached to a motor <NUM>, via suitable tool holding equipment such as a chuck <NUM>, for rotation about a second tool axis T wherein motor <NUM> is preferably an electrical motor, for example, a brushless motor. Motor <NUM> is preferably attached to body portion <NUM> via a motor clamp <NUM> and a bracket <NUM>. In operation, one or both of the chamfering tools <NUM>, <NUM> may be utilized for chamfering a particular workpiece. Tools <NUM> and <NUM> are rotatable in either direction about their respective axis of rotation.

Tool <NUM> is preferably capable of pivoting about an axis C. Therefore, it can be seen that regardless of the angular orientation of tool <NUM> about axis C, tool axis T will remain in a plane P (<FIG>). As can be viewed in <FIG>, a desired pivot angle of tool <NUM> may be set by angularly moving the motor <NUM> about axis C. To do so, screw <NUM>, which extends through an arcuate channel <NUM> in bracket <NUM> and into engagement with motor clamp <NUM>, is loosened such that the screw may move along channel <NUM> during pivoting of motor <NUM> about a pin <NUM> until the desired pivot angle is reached (see <FIG>, angle α, for example) at which time screw <NUM> is tightened so as to set the angular position of the tool <NUM>. Optionally, a spherical head locating screw may be mounted to motor clamp <NUM> so as to enable fine adjustments to be made to the final pivot angle and provide a repeatable hard stop for that manual actuation. While the pivoting of motor <NUM> may be carried out manually, the pivoting and setting of tool <NUM> may, alternatively, be motorized and/or computer controlled.

Preferably, first tool axis B and second tool axis T are not coincident with one another and, more preferably, are perpendicular to one another. Thus, preferably, plane P is perpendicular to tool axis B. Furthermore, it is preferred that the cutting circle defined by the tips <NUM> of the fly cutter <NUM> also lie in plane P as is shown in <FIG>.

Body portion <NUM> may further include cylinders <NUM>, <NUM>, such as hydraulic or pneumatic actuated cylinders, which will be further discussed below with reference to <FIG>.

Tool <NUM> is preferably movable in the direction of tool axis T from a retracted position (<FIG>) to an extended operational position as shown in <FIG>. The movement of tool <NUM> may be carried out by loosening screws <NUM> in motor clamp <NUM> and moving the motor <NUM> linearly until the intended operational position to tool <NUM> is reached and the screws <NUM> are then tightened. Linear movement of motor <NUM> and tool <NUM> may also be effected by hydraulic, pneumatic or electronic means, for example. Alternatively, the unclamping, moving and clamping of motor <NUM> and tool <NUM> may be automated and carried out via computer control. The amount of extension of tool <NUM> may be limited by a fixed stop mechanism or may be adjustable or programmable to any desired amount.

As mentioned above, <FIG> illustrate an extended and pivoted position of the tool <NUM> which is shown as a pencil milling tool. In <FIG>, for example, the pivot angle α is <NUM> degrees with respect to a reference line representative of the axis T position of <FIG>. The pivot angle may also be defined with respect to the A-axis, for example, or with respect to any other axis or reference position. The pivot angle may be fixed for a particular workpiece or may be adjusted from one workpiece to another such as for different gears on a shaft. It is also contemplated that the angular setting of tool <NUM> may be computer controlled and include the ability to change angular positions during the milling of a workpiece and coordinate angular positions with other chamfering device motions (e.g. motions along or about axes X, Y, Z, A and/or B).

<FIG> are exemplary views showing a tooth edge <NUM> formed at the intersection of a tooth flank surface <NUM> and an end face <NUM> of spur gear <NUM> located on a shaft <NUM>. A pencil mill <NUM> is moved along the tooth edge and forms a chamfer <NUM> along the tooth edge <NUM> and root portion <NUM> of the spur gear <NUM>. While a pencil mill <NUM> is shown, any suitable type and size milling tool may be utilized.

<FIG> shows a preferred embodiment of a chamfering device <NUM> of which the chamfering head <NUM> forms a part thereof. Chamfering device <NUM> further includes a base <NUM>, table <NUM> and a column <NUM>. Table <NUM> is movable in the X-direction via guide rails <NUM> and servo motor <NUM>. Column <NUM> is positioned on table <NUM> and is movable in the Y-direction via guide rails <NUM> and a servo motor <NUM> (<FIG>).

Column <NUM> includes a slide <NUM> movable in the Z-direction via guide rails <NUM> and servo motor <NUM>. A rotary or swivel plate <NUM> is positioned on table <NUM> for swiveling in direction S about an axis A by a servo motor (not shown). Body portion <NUM> is positioned on swivel plate <NUM>. Thus it can be seen that body portion <NUM> and hence, tools <NUM> and <NUM>, are capable of being positioned linearly in the X, Y and/or Z directions as well as angularly in direction S by swiveling about the A-axis.

Movement of table <NUM> in direction X, column <NUM> in direction Y, slide <NUM> in direction Z, angular motion S of swivel plate <NUM> about axis A, as well as rotation of tool <NUM> about axis B, is imparted by separate respective drive motors (<NUM>, <NUM>, <NUM> and <NUM> are shown). The above-named components are capable of independent movement with respect to one another or may move simultaneously with one another. Each of the drive motors is preferably associated with a feedback device such as a linear or rotary encoder as part of a CNC system which governs the operation of the drive motors in accordance with instructions input to a computer controller which may be a dedicated computer control (i.e. CNC) dedicated to the chamfering device <NUM> or the computer control (e.g. Siemens 840D series or Fanuc 30iB series, not shown) of an associated machine tool such as a gear hobbing machine.

Chamfering head <NUM> is movable along or about one or more of the axes X, Y, Z and/or A, and chamfering tools <NUM> and <NUM> may be swiveled (e.g. by <NUM> degrees) in direction S about the A-axis. By doing so, the two end faces of a workpiece can be accessed by the tools and the cutting direction of the chamfering tool <NUM> can be reversed at opposite ends of a tooth slot. While the direction of rotation of the drive of tool <NUM> remains the same in both swivel positions, the cutting directions of the tool are opposite to each other so that the tooth can be cut from inside to outside, or outside to inside, on the two end faces of the workpiece in both machining positions.

<FIG> illustrate another embodiment of the invention wherein body portion <NUM> further includes an assembly comprising one or more actuating cylinders <NUM>, <NUM>, such as hydraulic or pneumatic cylinders, along with respective cylinder rods <NUM>, <NUM> and a support surface <NUM>, such as a plate, on which one or more additional tools are positionable. A deburring tool <NUM>, preferably a disk-shaped deburring tool, and a non-contact type sensor <NUM> are shown and are removably attached to plate <NUM>. The cylinders <NUM>, <NUM> and rods <NUM>, <NUM> enable movement of the deburring tool <NUM> and sensor <NUM> between a retracted position (<FIG>) and an extended working position (<FIG> and <FIG>) which would be adjacent to a workpiece such as a gear.

Deburring tool <NUM> may function to remove burrs on the tooth edges of a workpiece resulting from a previous cutting process, such as hobbing, or as may result from a deburring process such as by tool <NUM> for example. Non-contact sensor <NUM> is utilized to determine the correct rotational position of a toothed workpiece whereby a rotary tool, such as tool <NUM>, may engage the workpiece in a meshing manner so as to not collide with and damage the teeth of the workpiece. Such a process is known to the artisan as "centering", "indexing" or "stock-dividing". Alternatively, a contact-type sensor (e.g. touch or tactile probe) may be utilized instead of non-contact sensor <NUM>.

While two cylinders and rods are shown, the invention is not limited thereto. A single cylinder and rod may be utilized for advancing and retracting a support surface such as a plate with one or more tools positioned thereon. Alternatively, other means of linear actuation may also be utilized. Furthermore, only one of a deburring tool and non-contact sensor may be included on plate <NUM>. Other tools (e.g. camera, RFID chip reader, bar code reader, optical scanner, etc.) may be included on plate <NUM>.

Chamfering device <NUM> may be included within another machine such as a gear hobbing machine or may be attached to another machine such as a gear hobbing machine. Chamfering device <NUM> may also be a stand-alone device. Workpieces may be transferred to and from chamfering device <NUM> via known transfer mechanism such as a robot, gantry loader, ring loader, carousel loader, etc. as will be understood by the skilled artisan.

<FIG> illustrates an example of a chamfering device <NUM> positioned adjacent to a gear hobbing machine <NUM> via a support table <NUM> attached to the hobbing machine. After hobbing, a workpiece is transferred to spindle <NUM> by a transfer mechanism <NUM> as mentioned above. A workpiece is held in spindle <NUM> by suitable workholding equipment (not shown) for rotation about axis W. Chamfering device <NUM> is moved in the X-direction so as to engage a workpiece with one or both of tools <NUM>, <NUM> (<FIG>) and/or one or more tools located on plate <NUM> (<FIG>) such as deburring tool deburring tool <NUM> and sensor <NUM>.

Although the invention has been discussed relative to gear hobbing machines, which generally produce spur and helical gears, the invention is not limited thereto. The inventive chamfering device may be utilized in conjunction with, and for gears produced by, bevel and hypoid gear cutting machines, gear gashing machines, gear shaping machines, power skiving machines, etc..

While tool <NUM> has been discussed as being pivotable and linear adjustable, the invention is not limited thereto. Tool <NUM> may be mounted in a fixed position relative to the body portion <NUM> or only one of pivoting and linear adjustability may be provided.

Claim 1:
A chamfering device for chamfering toothed workpieces, said chamfering device comprising:
a chamfering head (<NUM>) comprising a first tool axis of rotation (B),
said chamfering head being operable to rotate a first chamfering tool (<NUM>) about said first axis of rotation (B) thereby enabling chamfering by a first material removal method, the first chamfering tool being capable of being angularly positioned by swiveling about a swivel axis (A), such that, in both swivel positions for accessing the two end faces of the workpiece with the same direction of rotation of a drive for the first tool (<NUM>), the cutting directions are opposite to each other at opposite ends of a tooth slot of the workpiece,
wherein said chamfering head (<NUM>) comprises a second tool axis of rotation (T) not coincident with the first axis of rotation (B) and is further operable to rotate a second chamfering tool (<NUM>) about said second axis of rotation (T) thereby enabling chamfering by a second material removal method,
characterised in that said second chamfering tool (<NUM>) is swivelled together with the first chamfering tool (<NUM>) when swivelling about the swivel axis (A),
and in that said first chamfering tool (<NUM>) and said second chamfering tool (<NUM>) are different from one another and wherein said first material removal method and said second material removal method are different from one another.